diff options
Diffstat (limited to 'kernel/bpf/verifier.c')
| -rw-r--r-- | kernel/bpf/verifier.c | 9434 |
1 files changed, 7327 insertions, 2107 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 1cc945daa9c8..225666307bba 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4,6 +4,7 @@ * Copyright (c) 2018 Covalent IO, Inc. http://covalent.io */ #include <uapi/linux/btf.h> +#include <linux/bpf-cgroup.h> #include <linux/kernel.h> #include <linux/types.h> #include <linux/slab.h> @@ -19,6 +20,10 @@ #include <linux/sort.h> #include <linux/perf_event.h> #include <linux/ctype.h> +#include <linux/error-injection.h> +#include <linux/bpf_lsm.h> +#include <linux/btf_ids.h> +#include <linux/poison.h> #include "disasm.h" @@ -26,9 +31,11 @@ static const struct bpf_verifier_ops * const bpf_verifier_ops[] = { #define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \ [_id] = & _name ## _verifier_ops, #define BPF_MAP_TYPE(_id, _ops) +#define BPF_LINK_TYPE(_id, _name) #include <linux/bpf_types.h> #undef BPF_PROG_TYPE #undef BPF_MAP_TYPE +#undef BPF_LINK_TYPE }; /* bpf_check() is a static code analyzer that walks eBPF program @@ -42,7 +49,7 @@ static const struct bpf_verifier_ops * const bpf_verifier_ops[] = { * - unreachable insns exist (shouldn't be a forest. program = one function) * - out of bounds or malformed jumps * The second pass is all possible path descent from the 1st insn. - * Since it's analyzing all pathes through the program, the length of the + * Since it's analyzing all paths through the program, the length of the * analysis is limited to 64k insn, which may be hit even if total number of * insn is less then 4K, but there are too many branches that change stack/regs. * Number of 'branches to be analyzed' is limited to 1k @@ -127,7 +134,7 @@ static const struct bpf_verifier_ops * const bpf_verifier_ops[] = { * If it's ok, then verifier allows this BPF_CALL insn and looks at * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function - * returns ether pointer to map value or NULL. + * returns either pointer to map value or NULL. * * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off' * insn, the register holding that pointer in the true branch changes state to @@ -166,6 +173,8 @@ struct bpf_verifier_stack_elem { int insn_idx; int prev_insn_idx; struct bpf_verifier_stack_elem *next; + /* length of verifier log at the time this state was pushed on stack */ + u32 log_pos; }; #define BPF_COMPLEXITY_LIMIT_JMP_SEQ 8192 @@ -179,6 +188,9 @@ struct bpf_verifier_stack_elem { POISON_POINTER_DELTA)) #define BPF_MAP_PTR(X) ((struct bpf_map *)((X) & ~BPF_MAP_PTR_UNPRIV)) +static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx); +static int release_reference(struct bpf_verifier_env *env, int ref_obj_id); + static bool bpf_map_ptr_poisoned(const struct bpf_insn_aux_data *aux) { return BPF_MAP_PTR(aux->map_ptr_state) == BPF_MAP_PTR_POISON; @@ -221,17 +233,37 @@ static void bpf_map_key_store(struct bpf_insn_aux_data *aux, u64 state) (poisoned ? BPF_MAP_KEY_POISON : 0ULL); } +static bool bpf_pseudo_call(const struct bpf_insn *insn) +{ + return insn->code == (BPF_JMP | BPF_CALL) && + insn->src_reg == BPF_PSEUDO_CALL; +} + +static bool bpf_pseudo_kfunc_call(const struct bpf_insn *insn) +{ + return insn->code == (BPF_JMP | BPF_CALL) && + insn->src_reg == BPF_PSEUDO_KFUNC_CALL; +} + struct bpf_call_arg_meta { struct bpf_map *map_ptr; bool raw_mode; bool pkt_access; + u8 release_regno; int regno; int access_size; - s64 msize_smax_value; - u64 msize_umax_value; + int mem_size; + u64 msize_max_value; int ref_obj_id; + int map_uid; int func_id; + struct btf *btf; u32 btf_id; + struct btf *ret_btf; + u32 ret_btf_id; + u32 subprogno; + struct bpf_map_value_off_desc *kptr_off_desc; + u8 uninit_dynptr_regno; }; struct btf *btf_vmlinux; @@ -269,19 +301,33 @@ void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt, WARN_ONCE(n >= BPF_VERIFIER_TMP_LOG_SIZE - 1, "verifier log line truncated - local buffer too short\n"); - n = min(log->len_total - log->len_used - 1, n); - log->kbuf[n] = '\0'; - if (log->level == BPF_LOG_KERNEL) { - pr_err("BPF:%s\n", log->kbuf); + bool newline = n > 0 && log->kbuf[n - 1] == '\n'; + + pr_err("BPF: %s%s", log->kbuf, newline ? "" : "\n"); return; } + + n = min(log->len_total - log->len_used - 1, n); + log->kbuf[n] = '\0'; if (!copy_to_user(log->ubuf + log->len_used, log->kbuf, n + 1)) log->len_used += n; else log->ubuf = NULL; } +static void bpf_vlog_reset(struct bpf_verifier_log *log, u32 new_pos) +{ + char zero = 0; + + if (!bpf_verifier_log_needed(log)) + return; + + log->len_used = new_pos; + if (put_user(zero, log->ubuf + new_pos)) + log->ubuf = NULL; +} + /* log_level controls verbosity level of eBPF verifier. * bpf_verifier_log_write() is used to dump the verification trace to the log, * so the user can figure out what's wrong with the program @@ -325,6 +371,7 @@ __printf(2, 3) void bpf_log(struct bpf_verifier_log *log, bpf_verifier_vlog(log, fmt, args); va_end(args); } +EXPORT_SYMBOL_GPL(bpf_log); static const char *ltrim(const char *s) { @@ -362,8 +409,27 @@ __printf(3, 4) static void verbose_linfo(struct bpf_verifier_env *env, env->prev_linfo = linfo; } +static void verbose_invalid_scalar(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, + struct tnum *range, const char *ctx, + const char *reg_name) +{ + char tn_buf[48]; + + verbose(env, "At %s the register %s ", ctx, reg_name); + if (!tnum_is_unknown(reg->var_off)) { + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose(env, "has value %s", tn_buf); + } else { + verbose(env, "has unknown scalar value"); + } + tnum_strn(tn_buf, sizeof(tn_buf), *range); + verbose(env, " should have been in %s\n", tn_buf); +} + static bool type_is_pkt_pointer(enum bpf_reg_type type) { + type = base_type(type); return type == PTR_TO_PACKET || type == PTR_TO_PACKET_META; } @@ -376,12 +442,13 @@ static bool type_is_sk_pointer(enum bpf_reg_type type) type == PTR_TO_XDP_SOCK; } -static bool reg_type_may_be_null(enum bpf_reg_type type) +static bool reg_type_not_null(enum bpf_reg_type type) { - return type == PTR_TO_MAP_VALUE_OR_NULL || - type == PTR_TO_SOCKET_OR_NULL || - type == PTR_TO_SOCK_COMMON_OR_NULL || - type == PTR_TO_TCP_SOCK_OR_NULL; + return type == PTR_TO_SOCKET || + type == PTR_TO_TCP_SOCK || + type == PTR_TO_MAP_VALUE || + type == PTR_TO_MAP_KEY || + type == PTR_TO_SOCK_COMMON; } static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg) @@ -392,68 +459,142 @@ static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg) static bool reg_type_may_be_refcounted_or_null(enum bpf_reg_type type) { - return type == PTR_TO_SOCKET || - type == PTR_TO_SOCKET_OR_NULL || - type == PTR_TO_TCP_SOCK || - type == PTR_TO_TCP_SOCK_OR_NULL; + type = base_type(type); + return type == PTR_TO_SOCKET || type == PTR_TO_TCP_SOCK || + type == PTR_TO_MEM || type == PTR_TO_BTF_ID; } -static bool arg_type_may_be_refcounted(enum bpf_arg_type type) +static bool type_is_rdonly_mem(u32 type) { - return type == ARG_PTR_TO_SOCK_COMMON; + return type & MEM_RDONLY; } -/* Determine whether the function releases some resources allocated by another - * function call. The first reference type argument will be assumed to be - * released by release_reference(). - */ -static bool is_release_function(enum bpf_func_id func_id) +static bool type_may_be_null(u32 type) { - return func_id == BPF_FUNC_sk_release; + return type & PTR_MAYBE_NULL; } -static bool is_acquire_function(enum bpf_func_id func_id) +static bool is_acquire_function(enum bpf_func_id func_id, + const struct bpf_map *map) { - return func_id == BPF_FUNC_sk_lookup_tcp || - func_id == BPF_FUNC_sk_lookup_udp || - func_id == BPF_FUNC_skc_lookup_tcp; + enum bpf_map_type map_type = map ? map->map_type : BPF_MAP_TYPE_UNSPEC; + + if (func_id == BPF_FUNC_sk_lookup_tcp || + func_id == BPF_FUNC_sk_lookup_udp || + func_id == BPF_FUNC_skc_lookup_tcp || + func_id == BPF_FUNC_ringbuf_reserve || + func_id == BPF_FUNC_kptr_xchg) + return true; + + if (func_id == BPF_FUNC_map_lookup_elem && + (map_type == BPF_MAP_TYPE_SOCKMAP || + map_type == BPF_MAP_TYPE_SOCKHASH)) + return true; + + return false; } static bool is_ptr_cast_function(enum bpf_func_id func_id) { return func_id == BPF_FUNC_tcp_sock || - func_id == BPF_FUNC_sk_fullsock; -} - -/* string representation of 'enum bpf_reg_type' */ -static const char * const reg_type_str[] = { - [NOT_INIT] = "?", - [SCALAR_VALUE] = "inv", - [PTR_TO_CTX] = "ctx", - [CONST_PTR_TO_MAP] = "map_ptr", - [PTR_TO_MAP_VALUE] = "map_value", - [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null", - [PTR_TO_STACK] = "fp", - [PTR_TO_PACKET] = "pkt", - [PTR_TO_PACKET_META] = "pkt_meta", - [PTR_TO_PACKET_END] = "pkt_end", - [PTR_TO_FLOW_KEYS] = "flow_keys", - [PTR_TO_SOCKET] = "sock", - [PTR_TO_SOCKET_OR_NULL] = "sock_or_null", - [PTR_TO_SOCK_COMMON] = "sock_common", - [PTR_TO_SOCK_COMMON_OR_NULL] = "sock_common_or_null", - [PTR_TO_TCP_SOCK] = "tcp_sock", - [PTR_TO_TCP_SOCK_OR_NULL] = "tcp_sock_or_null", - [PTR_TO_TP_BUFFER] = "tp_buffer", - [PTR_TO_XDP_SOCK] = "xdp_sock", - [PTR_TO_BTF_ID] = "ptr_", -}; + func_id == BPF_FUNC_sk_fullsock || + func_id == BPF_FUNC_skc_to_tcp_sock || + func_id == BPF_FUNC_skc_to_tcp6_sock || + func_id == BPF_FUNC_skc_to_udp6_sock || + func_id == BPF_FUNC_skc_to_mptcp_sock || + func_id == BPF_FUNC_skc_to_tcp_timewait_sock || + func_id == BPF_FUNC_skc_to_tcp_request_sock; +} + +static bool is_dynptr_ref_function(enum bpf_func_id func_id) +{ + return func_id == BPF_FUNC_dynptr_data; +} + +static bool helper_multiple_ref_obj_use(enum bpf_func_id func_id, + const struct bpf_map *map) +{ + int ref_obj_uses = 0; + + if (is_ptr_cast_function(func_id)) + ref_obj_uses++; + if (is_acquire_function(func_id, map)) + ref_obj_uses++; + if (is_dynptr_ref_function(func_id)) + ref_obj_uses++; + + return ref_obj_uses > 1; +} + +static bool is_cmpxchg_insn(const struct bpf_insn *insn) +{ + return BPF_CLASS(insn->code) == BPF_STX && + BPF_MODE(insn->code) == BPF_ATOMIC && + insn->imm == BPF_CMPXCHG; +} + +/* string representation of 'enum bpf_reg_type' + * + * Note that reg_type_str() can not appear more than once in a single verbose() + * statement. + */ +static const char *reg_type_str(struct bpf_verifier_env *env, + enum bpf_reg_type type) +{ + char postfix[16] = {0}, prefix[32] = {0}; + static const char * const str[] = { + [NOT_INIT] = "?", + [SCALAR_VALUE] = "scalar", + [PTR_TO_CTX] = "ctx", + [CONST_PTR_TO_MAP] = "map_ptr", + [PTR_TO_MAP_VALUE] = "map_value", + [PTR_TO_STACK] = "fp", + [PTR_TO_PACKET] = "pkt", + [PTR_TO_PACKET_META] = "pkt_meta", + [PTR_TO_PACKET_END] = "pkt_end", + [PTR_TO_FLOW_KEYS] = "flow_keys", + [PTR_TO_SOCKET] = "sock", + [PTR_TO_SOCK_COMMON] = "sock_common", + [PTR_TO_TCP_SOCK] = "tcp_sock", + [PTR_TO_TP_BUFFER] = "tp_buffer", + [PTR_TO_XDP_SOCK] = "xdp_sock", + [PTR_TO_BTF_ID] = "ptr_", + [PTR_TO_MEM] = "mem", + [PTR_TO_BUF] = "buf", + [PTR_TO_FUNC] = "func", + [PTR_TO_MAP_KEY] = "map_key", + [PTR_TO_DYNPTR] = "dynptr_ptr", + }; + + if (type & PTR_MAYBE_NULL) { + if (base_type(type) == PTR_TO_BTF_ID) + strncpy(postfix, "or_null_", 16); + else + strncpy(postfix, "_or_null", 16); + } + + if (type & MEM_RDONLY) + strncpy(prefix, "rdonly_", 32); + if (type & MEM_ALLOC) + strncpy(prefix, "alloc_", 32); + if (type & MEM_USER) + strncpy(prefix, "user_", 32); + if (type & MEM_PERCPU) + strncpy(prefix, "percpu_", 32); + if (type & PTR_UNTRUSTED) + strncpy(prefix, "untrusted_", 32); + + snprintf(env->type_str_buf, TYPE_STR_BUF_LEN, "%s%s%s", + prefix, str[base_type(type)], postfix); + return env->type_str_buf; +} static char slot_type_char[] = { [STACK_INVALID] = '?', [STACK_SPILL] = 'r', [STACK_MISC] = 'm', [STACK_ZERO] = '0', + [STACK_DYNPTR] = 'd', }; static void print_liveness(struct bpf_verifier_env *env, @@ -469,6 +610,25 @@ static void print_liveness(struct bpf_verifier_env *env, verbose(env, "D"); } +static int get_spi(s32 off) +{ + return (-off - 1) / BPF_REG_SIZE; +} + +static bool is_spi_bounds_valid(struct bpf_func_state *state, int spi, int nr_slots) +{ + int allocated_slots = state->allocated_stack / BPF_REG_SIZE; + + /* We need to check that slots between [spi - nr_slots + 1, spi] are + * within [0, allocated_stack). + * + * Please note that the spi grows downwards. For example, a dynptr + * takes the size of two stack slots; the first slot will be at + * spi and the second slot will be at spi - 1. + */ + return spi - nr_slots + 1 >= 0 && spi < allocated_slots; +} + static struct bpf_func_state *func(struct bpf_verifier_env *env, const struct bpf_reg_state *reg) { @@ -477,14 +637,205 @@ static struct bpf_func_state *func(struct bpf_verifier_env *env, return cur->frame[reg->frameno]; } -const char *kernel_type_name(u32 id) +static const char *kernel_type_name(const struct btf* btf, u32 id) +{ + return btf_name_by_offset(btf, btf_type_by_id(btf, id)->name_off); +} + +static void mark_reg_scratched(struct bpf_verifier_env *env, u32 regno) +{ + env->scratched_regs |= 1U << regno; +} + +static void mark_stack_slot_scratched(struct bpf_verifier_env *env, u32 spi) +{ + env->scratched_stack_slots |= 1ULL << spi; +} + +static bool reg_scratched(const struct bpf_verifier_env *env, u32 regno) +{ + return (env->scratched_regs >> regno) & 1; +} + +static bool stack_slot_scratched(const struct bpf_verifier_env *env, u64 regno) +{ + return (env->scratched_stack_slots >> regno) & 1; +} + +static bool verifier_state_scratched(const struct bpf_verifier_env *env) +{ + return env->scratched_regs || env->scratched_stack_slots; +} + +static void mark_verifier_state_clean(struct bpf_verifier_env *env) +{ + env->scratched_regs = 0U; + env->scratched_stack_slots = 0ULL; +} + +/* Used for printing the entire verifier state. */ +static void mark_verifier_state_scratched(struct bpf_verifier_env *env) +{ + env->scratched_regs = ~0U; + env->scratched_stack_slots = ~0ULL; +} + +static enum bpf_dynptr_type arg_to_dynptr_type(enum bpf_arg_type arg_type) +{ + switch (arg_type & DYNPTR_TYPE_FLAG_MASK) { + case DYNPTR_TYPE_LOCAL: + return BPF_DYNPTR_TYPE_LOCAL; + case DYNPTR_TYPE_RINGBUF: + return BPF_DYNPTR_TYPE_RINGBUF; + default: + return BPF_DYNPTR_TYPE_INVALID; + } +} + +static bool dynptr_type_refcounted(enum bpf_dynptr_type type) +{ + return type == BPF_DYNPTR_TYPE_RINGBUF; +} + +static int mark_stack_slots_dynptr(struct bpf_verifier_env *env, struct bpf_reg_state *reg, + enum bpf_arg_type arg_type, int insn_idx) +{ + struct bpf_func_state *state = func(env, reg); + enum bpf_dynptr_type type; + int spi, i, id; + + spi = get_spi(reg->off); + + if (!is_spi_bounds_valid(state, spi, BPF_DYNPTR_NR_SLOTS)) + return -EINVAL; + + for (i = 0; i < BPF_REG_SIZE; i++) { + state->stack[spi].slot_type[i] = STACK_DYNPTR; + state->stack[spi - 1].slot_type[i] = STACK_DYNPTR; + } + + type = arg_to_dynptr_type(arg_type); + if (type == BPF_DYNPTR_TYPE_INVALID) + return -EINVAL; + + state->stack[spi].spilled_ptr.dynptr.first_slot = true; + state->stack[spi].spilled_ptr.dynptr.type = type; + state->stack[spi - 1].spilled_ptr.dynptr.type = type; + + if (dynptr_type_refcounted(type)) { + /* The id is used to track proper releasing */ + id = acquire_reference_state(env, insn_idx); + if (id < 0) + return id; + + state->stack[spi].spilled_ptr.id = id; + state->stack[spi - 1].spilled_ptr.id = id; + } + + return 0; +} + +static int unmark_stack_slots_dynptr(struct bpf_verifier_env *env, struct bpf_reg_state *reg) { - return btf_name_by_offset(btf_vmlinux, - btf_type_by_id(btf_vmlinux, id)->name_off); + struct bpf_func_state *state = func(env, reg); + int spi, i; + + spi = get_spi(reg->off); + + if (!is_spi_bounds_valid(state, spi, BPF_DYNPTR_NR_SLOTS)) + return -EINVAL; + + for (i = 0; i < BPF_REG_SIZE; i++) { + state->stack[spi].slot_type[i] = STACK_INVALID; + state->stack[spi - 1].slot_type[i] = STACK_INVALID; + } + + /* Invalidate any slices associated with this dynptr */ + if (dynptr_type_refcounted(state->stack[spi].spilled_ptr.dynptr.type)) { + release_reference(env, state->stack[spi].spilled_ptr.id); + state->stack[spi].spilled_ptr.id = 0; + state->stack[spi - 1].spilled_ptr.id = 0; + } + + state->stack[spi].spilled_ptr.dynptr.first_slot = false; + state->stack[spi].spilled_ptr.dynptr.type = 0; + state->stack[spi - 1].spilled_ptr.dynptr.type = 0; + + return 0; +} + +static bool is_dynptr_reg_valid_uninit(struct bpf_verifier_env *env, struct bpf_reg_state *reg) +{ + struct bpf_func_state *state = func(env, reg); + int spi = get_spi(reg->off); + int i; + + if (!is_spi_bounds_valid(state, spi, BPF_DYNPTR_NR_SLOTS)) + return true; + + for (i = 0; i < BPF_REG_SIZE; i++) { + if (state->stack[spi].slot_type[i] == STACK_DYNPTR || + state->stack[spi - 1].slot_type[i] == STACK_DYNPTR) + return false; + } + + return true; +} + +bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, + struct bpf_reg_state *reg) +{ + struct bpf_func_state *state = func(env, reg); + int spi = get_spi(reg->off); + int i; + + if (!is_spi_bounds_valid(state, spi, BPF_DYNPTR_NR_SLOTS) || + !state->stack[spi].spilled_ptr.dynptr.first_slot) + return false; + + for (i = 0; i < BPF_REG_SIZE; i++) { + if (state->stack[spi].slot_type[i] != STACK_DYNPTR || + state->stack[spi - 1].slot_type[i] != STACK_DYNPTR) + return false; + } + + return true; +} + +bool is_dynptr_type_expected(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, + enum bpf_arg_type arg_type) +{ + struct bpf_func_state *state = func(env, reg); + enum bpf_dynptr_type dynptr_type; + int spi = get_spi(reg->off); + + /* ARG_PTR_TO_DYNPTR takes any type of dynptr */ + if (arg_type == ARG_PTR_TO_DYNPTR) + return true; + + dynptr_type = arg_to_dynptr_type(arg_type); + + return state->stack[spi].spilled_ptr.dynptr.type == dynptr_type; +} + +/* The reg state of a pointer or a bounded scalar was saved when + * it was spilled to the stack. + */ +static bool is_spilled_reg(const struct bpf_stack_state *stack) +{ + return stack->slot_type[BPF_REG_SIZE - 1] == STACK_SPILL; +} + +static void scrub_spilled_slot(u8 *stype) +{ + if (*stype != STACK_INVALID) + *stype = STACK_MISC; } static void print_verifier_state(struct bpf_verifier_env *env, - const struct bpf_func_state *state) + const struct bpf_func_state *state, + bool print_all) { const struct bpf_reg_state *reg; enum bpf_reg_type t; @@ -497,59 +848,83 @@ static void print_verifier_state(struct bpf_verifier_env *env, t = reg->type; if (t == NOT_INIT) continue; + if (!print_all && !reg_scratched(env, i)) + continue; verbose(env, " R%d", i); print_liveness(env, reg->live); - verbose(env, "=%s", reg_type_str[t]); + verbose(env, "="); if (t == SCALAR_VALUE && reg->precise) verbose(env, "P"); if ((t == SCALAR_VALUE || t == PTR_TO_STACK) && tnum_is_const(reg->var_off)) { /* reg->off should be 0 for SCALAR_VALUE */ + verbose(env, "%s", t == SCALAR_VALUE ? "" : reg_type_str(env, t)); verbose(env, "%lld", reg->var_off.value + reg->off); } else { - if (t == PTR_TO_BTF_ID) - verbose(env, "%s", kernel_type_name(reg->btf_id)); - verbose(env, "(id=%d", reg->id); - if (reg_type_may_be_refcounted_or_null(t)) - verbose(env, ",ref_obj_id=%d", reg->ref_obj_id); + const char *sep = ""; + + verbose(env, "%s", reg_type_str(env, t)); + if (base_type(t) == PTR_TO_BTF_ID) + verbose(env, "%s", kernel_type_name(reg->btf, reg->btf_id)); + verbose(env, "("); +/* + * _a stands for append, was shortened to avoid multiline statements below. + * This macro is used to output a comma separated list of attributes. + */ +#define verbose_a(fmt, ...) ({ verbose(env, "%s" fmt, sep, __VA_ARGS__); sep = ","; }) + + if (reg->id) + verbose_a("id=%d", reg->id); + if (reg_type_may_be_refcounted_or_null(t) && reg->ref_obj_id) + verbose_a("ref_obj_id=%d", reg->ref_obj_id); if (t != SCALAR_VALUE) - verbose(env, ",off=%d", reg->off); + verbose_a("off=%d", reg->off); if (type_is_pkt_pointer(t)) - verbose(env, ",r=%d", reg->range); - else if (t == CONST_PTR_TO_MAP || - t == PTR_TO_MAP_VALUE || - t == PTR_TO_MAP_VALUE_OR_NULL) - verbose(env, ",ks=%d,vs=%d", - reg->map_ptr->key_size, - reg->map_ptr->value_size); + verbose_a("r=%d", reg->range); + else if (base_type(t) == CONST_PTR_TO_MAP || + base_type(t) == PTR_TO_MAP_KEY || + base_type(t) == PTR_TO_MAP_VALUE) + verbose_a("ks=%d,vs=%d", + reg->map_ptr->key_size, + reg->map_ptr->value_size); if (tnum_is_const(reg->var_off)) { /* Typically an immediate SCALAR_VALUE, but * could be a pointer whose offset is too big * for reg->off */ - verbose(env, ",imm=%llx", reg->var_off.value); + verbose_a("imm=%llx", reg->var_off.value); } else { if (reg->smin_value != reg->umin_value && reg->smin_value != S64_MIN) - verbose(env, ",smin_value=%lld", - (long long)reg->smin_value); + verbose_a("smin=%lld", (long long)reg->smin_value); if (reg->smax_value != reg->umax_value && reg->smax_value != S64_MAX) - verbose(env, ",smax_value=%lld", - (long long)reg->smax_value); + verbose_a("smax=%lld", (long long)reg->smax_value); if (reg->umin_value != 0) - verbose(env, ",umin_value=%llu", - (unsigned long long)reg->umin_value); + verbose_a("umin=%llu", (unsigned long long)reg->umin_value); if (reg->umax_value != U64_MAX) - verbose(env, ",umax_value=%llu", - (unsigned long long)reg->umax_value); + verbose_a("umax=%llu", (unsigned long long)reg->umax_value); if (!tnum_is_unknown(reg->var_off)) { char tn_buf[48]; tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); - verbose(env, ",var_off=%s", tn_buf); + verbose_a("var_off=%s", tn_buf); } + if (reg->s32_min_value != reg->smin_value && + reg->s32_min_value != S32_MIN) + verbose_a("s32_min=%d", (int)(reg->s32_min_value)); + if (reg->s32_max_value != reg->smax_value && + reg->s32_max_value != S32_MAX) + verbose_a("s32_max=%d", (int)(reg->s32_max_value)); + if (reg->u32_min_value != reg->umin_value && + reg->u32_min_value != U32_MIN) + verbose_a("u32_min=%d", (int)(reg->u32_min_value)); + if (reg->u32_max_value != reg->umax_value && + reg->u32_max_value != U32_MAX) + verbose_a("u32_max=%d", (int)(reg->u32_max_value)); } +#undef verbose_a + verbose(env, ")"); } } @@ -567,12 +942,14 @@ static void print_verifier_state(struct bpf_verifier_env *env, types_buf[BPF_REG_SIZE] = 0; if (!valid) continue; + if (!print_all && !stack_slot_scratched(env, i)) + continue; verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); print_liveness(env, state->stack[i].spilled_ptr.live); - if (state->stack[i].slot_type[0] == STACK_SPILL) { + if (is_spilled_reg(&state->stack[i])) { reg = &state->stack[i].spilled_ptr; t = reg->type; - verbose(env, "=%s", reg_type_str[t]); + verbose(env, "=%s", t == SCALAR_VALUE ? "" : reg_type_str(env, t)); if (t == SCALAR_VALUE && reg->precise) verbose(env, "P"); if (t == SCALAR_VALUE && tnum_is_const(reg->var_off)) @@ -587,84 +964,136 @@ static void print_verifier_state(struct bpf_verifier_env *env, if (state->refs[i].id) verbose(env, ",%d", state->refs[i].id); } + if (state->in_callback_fn) + verbose(env, " cb"); + if (state->in_async_callback_fn) + verbose(env, " async_cb"); verbose(env, "\n"); + mark_verifier_state_clean(env); +} + +static inline u32 vlog_alignment(u32 pos) +{ + return round_up(max(pos + BPF_LOG_MIN_ALIGNMENT / 2, BPF_LOG_ALIGNMENT), + BPF_LOG_MIN_ALIGNMENT) - pos - 1; } -#define COPY_STATE_FN(NAME, COUNT, FIELD, SIZE) \ -static int copy_##NAME##_state(struct bpf_func_state *dst, \ - const struct bpf_func_state *src) \ -{ \ - if (!src->FIELD) \ - return 0; \ - if (WARN_ON_ONCE(dst->COUNT < src->COUNT)) { \ - /* internal bug, make state invalid to reject the program */ \ - memset(dst, 0, sizeof(*dst)); \ - return -EFAULT; \ - } \ - memcpy(dst->FIELD, src->FIELD, \ - sizeof(*src->FIELD) * (src->COUNT / SIZE)); \ - return 0; \ -} -/* copy_reference_state() */ -COPY_STATE_FN(reference, acquired_refs, refs, 1) -/* copy_stack_state() */ -COPY_STATE_FN(stack, allocated_stack, stack, BPF_REG_SIZE) -#undef COPY_STATE_FN - -#define REALLOC_STATE_FN(NAME, COUNT, FIELD, SIZE) \ -static int realloc_##NAME##_state(struct bpf_func_state *state, int size, \ - bool copy_old) \ -{ \ - u32 old_size = state->COUNT; \ - struct bpf_##NAME##_state *new_##FIELD; \ - int slot = size / SIZE; \ - \ - if (size <= old_size || !size) { \ - if (copy_old) \ - return 0; \ - state->COUNT = slot * SIZE; \ - if (!size && old_size) { \ - kfree(state->FIELD); \ - state->FIELD = NULL; \ - } \ - return 0; \ - } \ - new_##FIELD = kmalloc_array(slot, sizeof(struct bpf_##NAME##_state), \ - GFP_KERNEL); \ - if (!new_##FIELD) \ - return -ENOMEM; \ - if (copy_old) { \ - if (state->FIELD) \ - memcpy(new_##FIELD, state->FIELD, \ - sizeof(*new_##FIELD) * (old_size / SIZE)); \ - memset(new_##FIELD + old_size / SIZE, 0, \ - sizeof(*new_##FIELD) * (size - old_size) / SIZE); \ - } \ - state->COUNT = slot * SIZE; \ - kfree(state->FIELD); \ - state->FIELD = new_##FIELD; \ - return 0; \ -} -/* realloc_reference_state() */ -REALLOC_STATE_FN(reference, acquired_refs, refs, 1) -/* realloc_stack_state() */ -REALLOC_STATE_FN(stack, allocated_stack, stack, BPF_REG_SIZE) -#undef REALLOC_STATE_FN - -/* do_check() starts with zero-sized stack in struct bpf_verifier_state to - * make it consume minimal amount of memory. check_stack_write() access from - * the program calls into realloc_func_state() to grow the stack size. - * Note there is a non-zero 'parent' pointer inside bpf_verifier_state - * which realloc_stack_state() copies over. It points to previous - * bpf_verifier_state which is never reallocated. +static void print_insn_state(struct bpf_verifier_env *env, + const struct bpf_func_state *state) +{ + if (env->prev_log_len && env->prev_log_len == env->log.len_used) { + /* remove new line character */ + bpf_vlog_reset(&env->log, env->prev_log_len - 1); + verbose(env, "%*c;", vlog_alignment(env->prev_insn_print_len), ' '); + } else { + verbose(env, "%d:", env->insn_idx); + } + print_verifier_state(env, state, false); +} + +/* copy array src of length n * size bytes to dst. dst is reallocated if it's too + * small to hold src. This is different from krealloc since we don't want to preserve + * the contents of dst. + * + * Leaves dst untouched if src is NULL or length is zero. Returns NULL if memory could + * not be allocated. */ -static int realloc_func_state(struct bpf_func_state *state, int stack_size, - int refs_size, bool copy_old) +static void *copy_array(void *dst, const void *src, size_t n, size_t size, gfp_t flags) { - int err = realloc_reference_state(state, refs_size, copy_old); - if (err) - return err; - return realloc_stack_state(state, stack_size, copy_old); + size_t bytes; + + if (ZERO_OR_NULL_PTR(src)) + goto out; + + if (unlikely(check_mul_overflow(n, size, &bytes))) + return NULL; + + if (ksize(dst) < bytes) { + kfree(dst); + dst = kmalloc_track_caller(bytes, flags); + if (!dst) + return NULL; + } + + memcpy(dst, src, bytes); +out: + return dst ? dst : ZERO_SIZE_PTR; +} + +/* resize an array from old_n items to new_n items. the array is reallocated if it's too + * small to hold new_n items. new items are zeroed out if the array grows. + * + * Contrary to krealloc_array, does not free arr if new_n is zero. + */ +static void *realloc_array(void *arr, size_t old_n, size_t new_n, size_t size) +{ + void *new_arr; + + if (!new_n || old_n == new_n) + goto out; + + new_arr = krealloc_array(arr, new_n, size, GFP_KERNEL); + if (!new_arr) { + kfree(arr); + return NULL; + } + arr = new_arr; + + if (new_n > old_n) + memset(arr + old_n * size, 0, (new_n - old_n) * size); + +out: + return arr ? arr : ZERO_SIZE_PTR; +} + +static int copy_reference_state(struct bpf_func_state *dst, const struct bpf_func_state *src) +{ + dst->refs = copy_array(dst->refs, src->refs, src->acquired_refs, + sizeof(struct bpf_reference_state), GFP_KERNEL); + if (!dst->refs) + return -ENOMEM; + + dst->acquired_refs = src->acquired_refs; + return 0; +} + +static int copy_stack_state(struct bpf_func_state *dst, const struct bpf_func_state *src) +{ + size_t n = src->allocated_stack / BPF_REG_SIZE; + + dst->stack = copy_array(dst->stack, src->stack, n, sizeof(struct bpf_stack_state), + GFP_KERNEL); + if (!dst->stack) + return -ENOMEM; + + dst->allocated_stack = src->allocated_stack; + return 0; +} + +static int resize_reference_state(struct bpf_func_state *state, size_t n) +{ + state->refs = realloc_array(state->refs, state->acquired_refs, n, + sizeof(struct bpf_reference_state)); + if (!state->refs) + return -ENOMEM; + + state->acquired_refs = n; + return 0; +} + +static int grow_stack_state(struct bpf_func_state *state, int size) +{ + size_t old_n = state->allocated_stack / BPF_REG_SIZE, n = size / BPF_REG_SIZE; + + if (old_n >= n) + return 0; + + state->stack = realloc_array(state->stack, old_n, n, sizeof(struct bpf_stack_state)); + if (!state->stack) + return -ENOMEM; + + state->allocated_stack = size; + return 0; } /* Acquire a pointer id from the env and update the state->refs to include @@ -678,12 +1107,13 @@ static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx) int new_ofs = state->acquired_refs; int id, err; - err = realloc_reference_state(state, state->acquired_refs + 1, true); + err = resize_reference_state(state, state->acquired_refs + 1); if (err) return err; id = ++env->id_gen; state->refs[new_ofs].id = id; state->refs[new_ofs].insn_idx = insn_idx; + state->refs[new_ofs].callback_ref = state->in_callback_fn ? state->frameno : 0; return id; } @@ -696,6 +1126,9 @@ static int release_reference_state(struct bpf_func_state *state, int ptr_id) last_idx = state->acquired_refs - 1; for (i = 0; i < state->acquired_refs; i++) { if (state->refs[i].id == ptr_id) { + /* Cannot release caller references in callbacks */ + if (state->in_callback_fn && state->refs[i].callback_ref != state->frameno) + return -EINVAL; if (last_idx && i != last_idx) memcpy(&state->refs[i], &state->refs[last_idx], sizeof(*state->refs)); @@ -707,18 +1140,6 @@ static int release_reference_state(struct bpf_func_state *state, int ptr_id) return -EINVAL; } -static int transfer_reference_state(struct bpf_func_state *dst, - struct bpf_func_state *src) -{ - int err = realloc_reference_state(dst, src->acquired_refs, false); - if (err) - return err; - err = copy_reference_state(dst, src); - if (err) - return err; - return 0; -} - static void free_func_state(struct bpf_func_state *state) { if (!state) @@ -757,10 +1178,6 @@ static int copy_func_state(struct bpf_func_state *dst, { int err; - err = realloc_func_state(dst, src->allocated_stack, src->acquired_refs, - false); - if (err) - return err; memcpy(dst, src, offsetof(struct bpf_func_state, acquired_refs)); err = copy_reference_state(dst, src); if (err) @@ -772,16 +1189,13 @@ static int copy_verifier_state(struct bpf_verifier_state *dst_state, const struct bpf_verifier_state *src) { struct bpf_func_state *dst; - u32 jmp_sz = sizeof(struct bpf_idx_pair) * src->jmp_history_cnt; int i, err; - if (dst_state->jmp_history_cnt < src->jmp_history_cnt) { - kfree(dst_state->jmp_history); - dst_state->jmp_history = kmalloc(jmp_sz, GFP_USER); - if (!dst_state->jmp_history) - return -ENOMEM; - } - memcpy(dst_state->jmp_history, src->jmp_history, jmp_sz); + dst_state->jmp_history = copy_array(dst_state->jmp_history, src->jmp_history, + src->jmp_history_cnt, sizeof(struct bpf_idx_pair), + GFP_USER); + if (!dst_state->jmp_history) + return -ENOMEM; dst_state->jmp_history_cnt = src->jmp_history_cnt; /* if dst has more stack frames then src frame, free them */ @@ -829,7 +1243,7 @@ static void update_branch_counts(struct bpf_verifier_env *env, struct bpf_verifi } static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx, - int *insn_idx) + int *insn_idx, bool pop_log) { struct bpf_verifier_state *cur = env->cur_state; struct bpf_verifier_stack_elem *elem, *head = env->head; @@ -843,6 +1257,8 @@ static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx, if (err) return err; } + if (pop_log) + bpf_vlog_reset(&env->log, head->log_pos); if (insn_idx) *insn_idx = head->insn_idx; if (prev_insn_idx) @@ -870,6 +1286,7 @@ static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env, elem->insn_idx = insn_idx; elem->prev_insn_idx = prev_insn_idx; elem->next = env->head; + elem->log_pos = env->log.len_used; env->head = elem; env->stack_size++; err = copy_verifier_state(&elem->st, cur); @@ -898,7 +1315,7 @@ err: free_verifier_state(env->cur_state, true); env->cur_state = NULL; /* pop all elements and return */ - while (!pop_stack(env, NULL, NULL)); + while (!pop_stack(env, NULL, NULL, false)); return NULL; } @@ -910,6 +1327,21 @@ static const int caller_saved[CALLER_SAVED_REGS] = { static void __mark_reg_not_init(const struct bpf_verifier_env *env, struct bpf_reg_state *reg); +/* This helper doesn't clear reg->id */ +static void ___mark_reg_known(struct bpf_reg_state *reg, u64 imm) +{ + reg->var_off = tnum_const(imm); + reg->smin_value = (s64)imm; + reg->smax_value = (s64)imm; + reg->umin_value = imm; + reg->umax_value = imm; + + reg->s32_min_value = (s32)imm; + reg->s32_max_value = (s32)imm; + reg->u32_min_value = (u32)imm; + reg->u32_max_value = (u32)imm; +} + /* Mark the unknown part of a register (variable offset or scalar value) as * known to have the value @imm. */ @@ -918,11 +1350,16 @@ static void __mark_reg_known(struct bpf_reg_state *reg, u64 imm) /* Clear id, off, and union(map_ptr, range) */ memset(((u8 *)reg) + sizeof(reg->type), 0, offsetof(struct bpf_reg_state, var_off) - sizeof(reg->type)); - reg->var_off = tnum_const(imm); - reg->smin_value = (s64)imm; - reg->smax_value = (s64)imm; - reg->umin_value = imm; - reg->umax_value = imm; + ___mark_reg_known(reg, imm); +} + +static void __mark_reg32_known(struct bpf_reg_state *reg, u64 imm) +{ + reg->var_off = tnum_const_subreg(reg->var_off, imm); + reg->s32_min_value = (s32)imm; + reg->s32_max_value = (s32)imm; + reg->u32_min_value = (u32)imm; + reg->u32_max_value = (u32)imm; } /* Mark the 'variable offset' part of a register as zero. This should be @@ -952,6 +1389,33 @@ static void mark_reg_known_zero(struct bpf_verifier_env *env, __mark_reg_known_zero(regs + regno); } +static void mark_ptr_not_null_reg(struct bpf_reg_state *reg) +{ + if (base_type(reg->type) == PTR_TO_MAP_VALUE) { + const struct bpf_map *map = reg->map_ptr; + + if (map->inner_map_meta) { + reg->type = CONST_PTR_TO_MAP; + reg->map_ptr = map->inner_map_meta; + /* transfer reg's id which is unique for every map_lookup_elem + * as UID of the inner map. + */ + if (map_value_has_timer(map->inner_map_meta)) + reg->map_uid = reg->id; + } else if (map->map_type == BPF_MAP_TYPE_XSKMAP) { + reg->type = PTR_TO_XDP_SOCK; + } else if (map->map_type == BPF_MAP_TYPE_SOCKMAP || + map->map_type == BPF_MAP_TYPE_SOCKHASH) { + reg->type = PTR_TO_SOCKET; + } else { + reg->type = PTR_TO_MAP_VALUE; + } + return; + } + + reg->type &= ~PTR_MAYBE_NULL; +} + static bool reg_is_pkt_pointer(const struct bpf_reg_state *reg) { return type_is_pkt_pointer(reg->type); @@ -977,8 +1441,52 @@ static bool reg_is_init_pkt_pointer(const struct bpf_reg_state *reg, tnum_equals_const(reg->var_off, 0); } -/* Attempts to improve min/max values based on var_off information */ -static void __update_reg_bounds(struct bpf_reg_state *reg) +/* Reset the min/max bounds of a register */ +static void __mark_reg_unbounded(struct bpf_reg_state *reg) +{ + reg->smin_value = S64_MIN; + reg->smax_value = S64_MAX; + reg->umin_value = 0; + reg->umax_value = U64_MAX; + + reg->s32_min_value = S32_MIN; + reg->s32_max_value = S32_MAX; + reg->u32_min_value = 0; + reg->u32_max_value = U32_MAX; +} + +static void __mark_reg64_unbounded(struct bpf_reg_state *reg) +{ + reg->smin_value = S64_MIN; + reg->smax_value = S64_MAX; + reg->umin_value = 0; + reg->umax_value = U64_MAX; +} + +static void __mark_reg32_unbounded(struct bpf_reg_state *reg) +{ + reg->s32_min_value = S32_MIN; + reg->s32_max_value = S32_MAX; + reg->u32_min_value = 0; + reg->u32_max_value = U32_MAX; +} + +static void __update_reg32_bounds(struct bpf_reg_state *reg) +{ + struct tnum var32_off = tnum_subreg(reg->var_off); + + /* min signed is max(sign bit) | min(other bits) */ + reg->s32_min_value = max_t(s32, reg->s32_min_value, + var32_off.value | (var32_off.mask & S32_MIN)); + /* max signed is min(sign bit) | max(other bits) */ + reg->s32_max_value = min_t(s32, reg->s32_max_value, + var32_off.value | (var32_off.mask & S32_MAX)); + reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)var32_off.value); + reg->u32_max_value = min(reg->u32_max_value, + (u32)(var32_off.value | var32_off.mask)); +} + +static void __update_reg64_bounds(struct bpf_reg_state *reg) { /* min signed is max(sign bit) | min(other bits) */ reg->smin_value = max_t(s64, reg->smin_value, @@ -991,8 +1499,48 @@ static void __update_reg_bounds(struct bpf_reg_state *reg) reg->var_off.value | reg->var_off.mask); } +static void __update_reg_bounds(struct bpf_reg_state *reg) +{ + __update_reg32_bounds(reg); + __update_reg64_bounds(reg); +} + /* Uses signed min/max values to inform unsigned, and vice-versa */ -static void __reg_deduce_bounds(struct bpf_reg_state *reg) +static void __reg32_deduce_bounds(struct bpf_reg_state *reg) +{ + /* Learn sign from signed bounds. + * If we cannot cross the sign boundary, then signed and unsigned bounds + * are the same, so combine. This works even in the negative case, e.g. + * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff. + */ + if (reg->s32_min_value >= 0 || reg->s32_max_value < 0) { + reg->s32_min_value = reg->u32_min_value = + max_t(u32, reg->s32_min_value, reg->u32_min_value); + reg->s32_max_value = reg->u32_max_value = + min_t(u32, reg->s32_max_value, reg->u32_max_value); + return; + } + /* Learn sign from unsigned bounds. Signed bounds cross the sign + * boundary, so we must be careful. + */ + if ((s32)reg->u32_max_value >= 0) { + /* Positive. We can't learn anything from the smin, but smax + * is positive, hence safe. + */ + reg->s32_min_value = reg->u32_min_value; + reg->s32_max_value = reg->u32_max_value = + min_t(u32, reg->s32_max_value, reg->u32_max_value); + } else if ((s32)reg->u32_min_value < 0) { + /* Negative. We can't learn anything from the smax, but smin + * is negative, hence safe. + */ + reg->s32_min_value = reg->u32_min_value = + max_t(u32, reg->s32_min_value, reg->u32_min_value); + reg->s32_max_value = reg->u32_max_value; + } +} + +static void __reg64_deduce_bounds(struct bpf_reg_state *reg) { /* Learn sign from signed bounds. * If we cannot cross the sign boundary, then signed and unsigned bounds @@ -1026,32 +1574,107 @@ static void __reg_deduce_bounds(struct bpf_reg_state *reg) } } +static void __reg_deduce_bounds(struct bpf_reg_state *reg) +{ + __reg32_deduce_bounds(reg); + __reg64_deduce_bounds(reg); +} + /* Attempts to improve var_off based on unsigned min/max information */ static void __reg_bound_offset(struct bpf_reg_state *reg) { - reg->var_off = tnum_intersect(reg->var_off, - tnum_range(reg->umin_value, - reg->umax_value)); + struct tnum var64_off = tnum_intersect(reg->var_off, + tnum_range(reg->umin_value, + reg->umax_value)); + struct tnum var32_off = tnum_intersect(tnum_subreg(reg->var_off), + tnum_range(reg->u32_min_value, + reg->u32_max_value)); + + reg->var_off = tnum_or(tnum_clear_subreg(var64_off), var32_off); } -static void __reg_bound_offset32(struct bpf_reg_state *reg) +static void reg_bounds_sync(struct bpf_reg_state *reg) { - u64 mask = 0xffffFFFF; - struct tnum range = tnum_range(reg->umin_value & mask, - reg->umax_value & mask); - struct tnum lo32 = tnum_cast(reg->var_off, 4); - struct tnum hi32 = tnum_lshift(tnum_rshift(reg->var_off, 32), 32); + /* We might have learned new bounds from the var_off. */ + __update_reg_bounds(reg); + /* We might have learned something about the sign bit. */ + __reg_deduce_bounds(reg); + /* We might have learned some bits from the bounds. */ + __reg_bound_offset(reg); + /* Intersecting with the old var_off might have improved our bounds + * slightly, e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc), + * then new var_off is (0; 0x7f...fc) which improves our umax. + */ + __update_reg_bounds(reg); +} - reg->var_off = tnum_or(hi32, tnum_intersect(lo32, range)); +static bool __reg32_bound_s64(s32 a) +{ + return a >= 0 && a <= S32_MAX; } -/* Reset the min/max bounds of a register */ -static void __mark_reg_unbounded(struct bpf_reg_state *reg) +static void __reg_assign_32_into_64(struct bpf_reg_state *reg) { - reg->smin_value = S64_MIN; - reg->smax_value = S64_MAX; - reg->umin_value = 0; - reg->umax_value = U64_MAX; + reg->umin_value = reg->u32_min_value; + reg->umax_value = reg->u32_max_value; + + /* Attempt to pull 32-bit signed bounds into 64-bit bounds but must + * be positive otherwise set to worse case bounds and refine later + * from tnum. + */ + if (__reg32_bound_s64(reg->s32_min_value) && + __reg32_bound_s64(reg->s32_max_value)) { + reg->smin_value = reg->s32_min_value; + reg->smax_value = reg->s32_max_value; + } else { + reg->smin_value = 0; + reg->smax_value = U32_MAX; + } +} + +static void __reg_combine_32_into_64(struct bpf_reg_state *reg) +{ + /* special case when 64-bit register has upper 32-bit register + * zeroed. Typically happens after zext or <<32, >>32 sequence + * allowing us to use 32-bit bounds directly, + */ + if (tnum_equals_const(tnum_clear_subreg(reg->var_off), 0)) { + __reg_assign_32_into_64(reg); + } else { + /* Otherwise the best we can do is push lower 32bit known and + * unknown bits into register (var_off set from jmp logic) + * then learn as much as possible from the 64-bit tnum + * known and unknown bits. The previous smin/smax bounds are + * invalid here because of jmp32 compare so mark them unknown + * so they do not impact tnum bounds calculation. + */ + __mark_reg64_unbounded(reg); + } + reg_bounds_sync(reg); +} + +static bool __reg64_bound_s32(s64 a) +{ + return a >= S32_MIN && a <= S32_MAX; +} + +static bool __reg64_bound_u32(u64 a) +{ + return a >= U32_MIN && a <= U32_MAX; +} + +static void __reg_combine_64_into_32(struct bpf_reg_state *reg) +{ + __mark_reg32_unbounded(reg); + if (__reg64_bound_s32(reg->smin_value) && __reg64_bound_s32(reg->smax_value)) { + reg->s32_min_value = (s32)reg->smin_value; + reg->s32_max_value = (s32)reg->smax_value; + } + if (__reg64_bound_u32(reg->umin_value) && __reg64_bound_u32(reg->umax_value)) { + reg->u32_min_value = (u32)reg->umin_value; + reg->u32_max_value = (u32)reg->umax_value; + } + reg_bounds_sync(reg); } /* Mark a register as having a completely unknown (scalar) value. */ @@ -1066,8 +1689,7 @@ static void __mark_reg_unknown(const struct bpf_verifier_env *env, reg->type = SCALAR_VALUE; reg->var_off = tnum_unknown; reg->frameno = 0; - reg->precise = env->subprog_cnt > 1 || !env->allow_ptr_leaks ? - true : false; + reg->precise = env->subprog_cnt > 1 || !env->bpf_capable; __mark_reg_unbounded(reg); } @@ -1104,6 +1726,22 @@ static void mark_reg_not_init(struct bpf_verifier_env *env, __mark_reg_not_init(env, regs + regno); } +static void mark_btf_ld_reg(struct bpf_verifier_env *env, + struct bpf_reg_state *regs, u32 regno, + enum bpf_reg_type reg_type, + struct btf *btf, u32 btf_id, + enum bpf_type_flag flag) +{ + if (reg_type == SCALAR_VALUE) { + mark_reg_unknown(env, regs, regno); + return; + } + mark_reg_known_zero(env, regs, regno); + regs[regno].type = PTR_TO_BTF_ID | flag; + regs[regno].btf = btf; + regs[regno].btf_id = btf_id; +} + #define DEF_NOT_SUBREG (0) static void init_reg_state(struct bpf_verifier_env *env, struct bpf_func_state *state) @@ -1132,9 +1770,59 @@ static void init_func_state(struct bpf_verifier_env *env, state->callsite = callsite; state->frameno = frameno; state->subprogno = subprogno; + state->callback_ret_range = tnum_range(0, 0); init_reg_state(env, state); + mark_verifier_state_scratched(env); } +/* Similar to push_stack(), but for async callbacks */ +static struct bpf_verifier_state *push_async_cb(struct bpf_verifier_env *env, + int insn_idx, int prev_insn_idx, + int subprog) +{ + struct bpf_verifier_stack_elem *elem; + struct bpf_func_state *frame; + + elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL); + if (!elem) + goto err; + + elem->insn_idx = insn_idx; + elem->prev_insn_idx = prev_insn_idx; + elem->next = env->head; + elem->log_pos = env->log.len_used; + env->head = elem; + env->stack_size++; + if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) { + verbose(env, + "The sequence of %d jumps is too complex for async cb.\n", + env->stack_size); + goto err; + } + /* Unlike push_stack() do not copy_verifier_state(). + * The caller state doesn't matter. + * This is async callback. It starts in a fresh stack. + * Initialize it similar to do_check_common(). + */ + elem->st.branches = 1; + frame = kzalloc(sizeof(*frame), GFP_KERNEL); + if (!frame) + goto err; + init_func_state(env, frame, + BPF_MAIN_FUNC /* callsite */, + 0 /* frameno within this callchain */, + subprog /* subprog number within this prog */); + elem->st.frame[0] = frame; + return &elem->st; +err: + free_verifier_state(env->cur_state, true); + env->cur_state = NULL; + /* pop all elements and return */ + while (!pop_stack(env, NULL, NULL, false)); + return NULL; +} + + enum reg_arg_type { SRC_OP, /* register is used as source operand */ DST_OP, /* register is used as destination operand */ @@ -1170,40 +1858,348 @@ static int add_subprog(struct bpf_verifier_env *env, int off) } ret = find_subprog(env, off); if (ret >= 0) - return 0; + return ret; if (env->subprog_cnt >= BPF_MAX_SUBPROGS) { verbose(env, "too many subprograms\n"); return -E2BIG; } + /* determine subprog starts. The end is one before the next starts */ env->subprog_info[env->subprog_cnt++].start = off; sort(env->subprog_info, env->subprog_cnt, sizeof(env->subprog_info[0]), cmp_subprogs, NULL); + return env->subprog_cnt - 1; +} + +#define MAX_KFUNC_DESCS 256 +#define MAX_KFUNC_BTFS 256 + +struct bpf_kfunc_desc { + struct btf_func_model func_model; + u32 func_id; + s32 imm; + u16 offset; +}; + +struct bpf_kfunc_btf { + struct btf *btf; + struct module *module; + u16 offset; +}; + +struct bpf_kfunc_desc_tab { + struct bpf_kfunc_desc descs[MAX_KFUNC_DESCS]; + u32 nr_descs; +}; + +struct bpf_kfunc_btf_tab { + struct bpf_kfunc_btf descs[MAX_KFUNC_BTFS]; + u32 nr_descs; +}; + +static int kfunc_desc_cmp_by_id_off(const void *a, const void *b) +{ + const struct bpf_kfunc_desc *d0 = a; + const struct bpf_kfunc_desc *d1 = b; + + /* func_id is not greater than BTF_MAX_TYPE */ + return d0->func_id - d1->func_id ?: d0->offset - d1->offset; +} + +static int kfunc_btf_cmp_by_off(const void *a, const void *b) +{ + const struct bpf_kfunc_btf *d0 = a; + const struct bpf_kfunc_btf *d1 = b; + + return d0->offset - d1->offset; +} + +static const struct bpf_kfunc_desc * +find_kfunc_desc(const struct bpf_prog *prog, u32 func_id, u16 offset) +{ + struct bpf_kfunc_desc desc = { + .func_id = func_id, + .offset = offset, + }; + struct bpf_kfunc_desc_tab *tab; + + tab = prog->aux->kfunc_tab; + return bsearch(&desc, tab->descs, tab->nr_descs, + sizeof(tab->descs[0]), kfunc_desc_cmp_by_id_off); +} + +static struct btf *__find_kfunc_desc_btf(struct bpf_verifier_env *env, + s16 offset) +{ + struct bpf_kfunc_btf kf_btf = { .offset = offset }; + struct bpf_kfunc_btf_tab *tab; + struct bpf_kfunc_btf *b; + struct module *mod; + struct btf *btf; + int btf_fd; + + tab = env->prog->aux->kfunc_btf_tab; + b = bsearch(&kf_btf, tab->descs, tab->nr_descs, + sizeof(tab->descs[0]), kfunc_btf_cmp_by_off); + if (!b) { + if (tab->nr_descs == MAX_KFUNC_BTFS) { + verbose(env, "too many different module BTFs\n"); + return ERR_PTR(-E2BIG); + } + + if (bpfptr_is_null(env->fd_array)) { + verbose(env, "kfunc offset > 0 without fd_array is invalid\n"); + return ERR_PTR(-EPROTO); + } + + if (copy_from_bpfptr_offset(&btf_fd, env->fd_array, + offset * sizeof(btf_fd), + sizeof(btf_fd))) + return ERR_PTR(-EFAULT); + + btf = btf_get_by_fd(btf_fd); + if (IS_ERR(btf)) { + verbose(env, "invalid module BTF fd specified\n"); + return btf; + } + + if (!btf_is_module(btf)) { + verbose(env, "BTF fd for kfunc is not a module BTF\n"); + btf_put(btf); + return ERR_PTR(-EINVAL); + } + + mod = btf_try_get_module(btf); + if (!mod) { + btf_put(btf); + return ERR_PTR(-ENXIO); + } + + b = &tab->descs[tab->nr_descs++]; + b->btf = btf; + b->module = mod; + b->offset = offset; + + sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]), + kfunc_btf_cmp_by_off, NULL); + } + return b->btf; +} + +void bpf_free_kfunc_btf_tab(struct bpf_kfunc_btf_tab *tab) +{ + if (!tab) + return; + + while (tab->nr_descs--) { + module_put(tab->descs[tab->nr_descs].module); + btf_put(tab->descs[tab->nr_descs].btf); + } + kfree(tab); +} + +static struct btf *find_kfunc_desc_btf(struct bpf_verifier_env *env, s16 offset) +{ + if (offset) { + if (offset < 0) { + /* In the future, this can be allowed to increase limit + * of fd index into fd_array, interpreted as u16. + */ + verbose(env, "negative offset disallowed for kernel module function call\n"); + return ERR_PTR(-EINVAL); + } + + return __find_kfunc_desc_btf(env, offset); + } + return btf_vmlinux ?: ERR_PTR(-ENOENT); +} + +static int add_kfunc_call(struct bpf_verifier_env *env, u32 func_id, s16 offset) +{ + const struct btf_type *func, *func_proto; + struct bpf_kfunc_btf_tab *btf_tab; + struct bpf_kfunc_desc_tab *tab; + struct bpf_prog_aux *prog_aux; + struct bpf_kfunc_desc *desc; + const char *func_name; + struct btf *desc_btf; + unsigned long call_imm; + unsigned long addr; + int err; + + prog_aux = env->prog->aux; + tab = prog_aux->kfunc_tab; + btf_tab = prog_aux->kfunc_btf_tab; + if (!tab) { + if (!btf_vmlinux) { + verbose(env, "calling kernel function is not supported without CONFIG_DEBUG_INFO_BTF\n"); + return -ENOTSUPP; + } + + if (!env->prog->jit_requested) { + verbose(env, "JIT is required for calling kernel function\n"); + return -ENOTSUPP; + } + + if (!bpf_jit_supports_kfunc_call()) { + verbose(env, "JIT does not support calling kernel function\n"); + return -ENOTSUPP; + } + + if (!env->prog->gpl_compatible) { + verbose(env, "cannot call kernel function from non-GPL compatible program\n"); + return -EINVAL; + } + + tab = kzalloc(sizeof(*tab), GFP_KERNEL); + if (!tab) + return -ENOMEM; + prog_aux->kfunc_tab = tab; + } + + /* func_id == 0 is always invalid, but instead of returning an error, be + * conservative and wait until the code elimination pass before returning + * error, so that invalid calls that get pruned out can be in BPF programs + * loaded from userspace. It is also required that offset be untouched + * for such calls. + */ + if (!func_id && !offset) + return 0; + + if (!btf_tab && offset) { + btf_tab = kzalloc(sizeof(*btf_tab), GFP_KERNEL); + if (!btf_tab) + return -ENOMEM; + prog_aux->kfunc_btf_tab = btf_tab; + } + + desc_btf = find_kfunc_desc_btf(env, offset); + if (IS_ERR(desc_btf)) { + verbose(env, "failed to find BTF for kernel function\n"); + return PTR_ERR(desc_btf); + } + + if (find_kfunc_desc(env->prog, func_id, offset)) + return 0; + + if (tab->nr_descs == MAX_KFUNC_DESCS) { + verbose(env, "too many different kernel function calls\n"); + return -E2BIG; + } + + func = btf_type_by_id(desc_btf, func_id); + if (!func || !btf_type_is_func(func)) { + verbose(env, "kernel btf_id %u is not a function\n", + func_id); + return -EINVAL; + } + func_proto = btf_type_by_id(desc_btf, func->type); + if (!func_proto || !btf_type_is_func_proto(func_proto)) { + verbose(env, "kernel function btf_id %u does not have a valid func_proto\n", + func_id); + return -EINVAL; + } + + func_name = btf_name_by_offset(desc_btf, func->name_off); + addr = kallsyms_lookup_name(func_name); + if (!addr) { + verbose(env, "cannot find address for kernel function %s\n", + func_name); + return -EINVAL; + } + + call_imm = BPF_CALL_IMM(addr); + /* Check whether or not the relative offset overflows desc->imm */ + if ((unsigned long)(s32)call_imm != call_imm) { + verbose(env, "address of kernel function %s is out of range\n", + func_name); + return -EINVAL; + } + + desc = &tab->descs[tab->nr_descs++]; + desc->func_id = func_id; + desc->imm = call_imm; + desc->offset = offset; + err = btf_distill_func_proto(&env->log, desc_btf, + func_proto, func_name, + &desc->func_model); + if (!err) + sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]), + kfunc_desc_cmp_by_id_off, NULL); + return err; +} + +static int kfunc_desc_cmp_by_imm(const void *a, const void *b) +{ + const struct bpf_kfunc_desc *d0 = a; + const struct bpf_kfunc_desc *d1 = b; + + if (d0->imm > d1->imm) + return 1; + else if (d0->imm < d1->imm) + return -1; return 0; } -static int check_subprogs(struct bpf_verifier_env *env) +static void sort_kfunc_descs_by_imm(struct bpf_prog *prog) +{ + struct bpf_kfunc_desc_tab *tab; + + tab = prog->aux->kfunc_tab; + if (!tab) + return; + + sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]), + kfunc_desc_cmp_by_imm, NULL); +} + +bool bpf_prog_has_kfunc_call(const struct bpf_prog *prog) +{ + return !!prog->aux->kfunc_tab; +} + +const struct btf_func_model * +bpf_jit_find_kfunc_model(const struct bpf_prog *prog, + const struct bpf_insn *insn) +{ + const struct bpf_kfunc_desc desc = { + .imm = insn->imm, + }; + const struct bpf_kfunc_desc *res; + struct bpf_kfunc_desc_tab *tab; + + tab = prog->aux->kfunc_tab; + res = bsearch(&desc, tab->descs, tab->nr_descs, + sizeof(tab->descs[0]), kfunc_desc_cmp_by_imm); + + return res ? &res->func_model : NULL; +} + +static int add_subprog_and_kfunc(struct bpf_verifier_env *env) { - int i, ret, subprog_start, subprog_end, off, cur_subprog = 0; struct bpf_subprog_info *subprog = env->subprog_info; struct bpf_insn *insn = env->prog->insnsi; - int insn_cnt = env->prog->len; + int i, ret, insn_cnt = env->prog->len; /* Add entry function. */ ret = add_subprog(env, 0); - if (ret < 0) + if (ret) return ret; - /* determine subprog starts. The end is one before the next starts */ - for (i = 0; i < insn_cnt; i++) { - if (insn[i].code != (BPF_JMP | BPF_CALL)) - continue; - if (insn[i].src_reg != BPF_PSEUDO_CALL) + for (i = 0; i < insn_cnt; i++, insn++) { + if (!bpf_pseudo_func(insn) && !bpf_pseudo_call(insn) && + !bpf_pseudo_kfunc_call(insn)) continue; - if (!env->allow_ptr_leaks) { - verbose(env, "function calls to other bpf functions are allowed for root only\n"); + + if (!env->bpf_capable) { + verbose(env, "loading/calling other bpf or kernel functions are allowed for CAP_BPF and CAP_SYS_ADMIN\n"); return -EPERM; } - ret = add_subprog(env, i + insn[i].imm + 1); + + if (bpf_pseudo_func(insn) || bpf_pseudo_call(insn)) + ret = add_subprog(env, i + insn->imm + 1); + else + ret = add_kfunc_call(env, insn->imm, insn->off); + if (ret < 0) return ret; } @@ -1217,12 +2213,29 @@ static int check_subprogs(struct bpf_verifier_env *env) for (i = 0; i < env->subprog_cnt; i++) verbose(env, "func#%d @%d\n", i, subprog[i].start); + return 0; +} + +static int check_subprogs(struct bpf_verifier_env *env) +{ + int i, subprog_start, subprog_end, off, cur_subprog = 0; + struct bpf_subprog_info *subprog = env->subprog_info; + struct bpf_insn *insn = env->prog->insnsi; + int insn_cnt = env->prog->len; + /* now check that all jumps are within the same subprog */ subprog_start = subprog[cur_subprog].start; subprog_end = subprog[cur_subprog + 1].start; for (i = 0; i < insn_cnt; i++) { u8 code = insn[i].code; + if (code == (BPF_JMP | BPF_CALL) && + insn[i].imm == BPF_FUNC_tail_call && + insn[i].src_reg != BPF_PSEUDO_CALL) + subprog[cur_subprog].has_tail_call = true; + if (BPF_CLASS(code) == BPF_LD && + (BPF_MODE(code) == BPF_ABS || BPF_MODE(code) == BPF_IND)) + subprog[cur_subprog].has_ld_abs = true; if (BPF_CLASS(code) != BPF_JMP && BPF_CLASS(code) != BPF_JMP32) goto next; if (BPF_OP(code) == BPF_EXIT || BPF_OP(code) == BPF_CALL) @@ -1268,7 +2281,7 @@ static int mark_reg_read(struct bpf_verifier_env *env, break; if (parent->live & REG_LIVE_DONE) { verbose(env, "verifier BUG type %s var_off %lld off %d\n", - reg_type_str[parent->type], + reg_type_str(env, parent->type), parent->var_off.value, parent->off); return -EFAULT; } @@ -1355,7 +2368,11 @@ static bool is_reg64(struct bpf_verifier_env *env, struct bpf_insn *insn, } if (class == BPF_STX) { - if (reg->type != SCALAR_VALUE) + /* BPF_STX (including atomic variants) has multiple source + * operands, one of which is a ptr. Check whether the caller is + * asking about it. + */ + if (t == SRC_OP && reg->type != SCALAR_VALUE) return true; return BPF_SIZE(code) == BPF_DW; } @@ -1387,22 +2404,38 @@ static bool is_reg64(struct bpf_verifier_env *env, struct bpf_insn *insn, return true; } -/* Return TRUE if INSN doesn't have explicit value define. */ -static bool insn_no_def(struct bpf_insn *insn) +/* Return the regno defined by the insn, or -1. */ +static int insn_def_regno(const struct bpf_insn *insn) { - u8 class = BPF_CLASS(insn->code); - - return (class == BPF_JMP || class == BPF_JMP32 || - class == BPF_STX || class == BPF_ST); + switch (BPF_CLASS(insn->code)) { + case BPF_JMP: + case BPF_JMP32: + case BPF_ST: + return -1; + case BPF_STX: + if (BPF_MODE(insn->code) == BPF_ATOMIC && + (insn->imm & BPF_FETCH)) { + if (insn->imm == BPF_CMPXCHG) + return BPF_REG_0; + else + return insn->src_reg; + } else { + return -1; + } + default: + return insn->dst_reg; + } } /* Return TRUE if INSN has defined any 32-bit value explicitly. */ static bool insn_has_def32(struct bpf_verifier_env *env, struct bpf_insn *insn) { - if (insn_no_def(insn)) + int dst_reg = insn_def_regno(insn); + + if (dst_reg == -1) return false; - return !is_reg64(env, insn, insn->dst_reg, NULL, DST_OP); + return !is_reg64(env, insn, dst_reg, NULL, DST_OP); } static void mark_insn_zext(struct bpf_verifier_env *env, @@ -1432,6 +2465,8 @@ static int check_reg_arg(struct bpf_verifier_env *env, u32 regno, return -EINVAL; } + mark_reg_scratched(env, regno); + reg = ®s[regno]; rw64 = is_reg64(env, insn, regno, reg, t); if (t == SRC_OP) { @@ -1498,6 +2533,22 @@ static int get_prev_insn_idx(struct bpf_verifier_state *st, int i, return i; } +static const char *disasm_kfunc_name(void *data, const struct bpf_insn *insn) +{ + const struct btf_type *func; + struct btf *desc_btf; + + if (insn->src_reg != BPF_PSEUDO_KFUNC_CALL) + return NULL; + + desc_btf = find_kfunc_desc_btf(data, insn->off); + if (IS_ERR(desc_btf)) + return "<error>"; + + func = btf_type_by_id(desc_btf, insn->imm); + return btf_name_by_offset(desc_btf, func->name_off); +} + /* For given verifier state backtrack_insn() is called from the last insn to * the first insn. Its purpose is to compute a bitmask of registers and * stack slots that needs precision in the parent verifier state. @@ -1506,6 +2557,7 @@ static int backtrack_insn(struct bpf_verifier_env *env, int idx, u32 *reg_mask, u64 *stack_mask) { const struct bpf_insn_cbs cbs = { + .cb_call = disasm_kfunc_name, .cb_print = verbose, .private_data = env, }; @@ -1519,7 +2571,7 @@ static int backtrack_insn(struct bpf_verifier_env *env, int idx, if (insn->code == 0) return 0; - if (env->log.level & BPF_LOG_LEVEL) { + if (env->log.level & BPF_LOG_LEVEL2) { verbose(env, "regs=%x stack=%llx before ", *reg_mask, *stack_mask); verbose(env, "%d: ", idx); print_bpf_insn(&cbs, insn, env->allow_ptr_leaks); @@ -1569,8 +2621,6 @@ static int backtrack_insn(struct bpf_verifier_env *env, int idx, */ if (insn->src_reg != BPF_REG_FP) return 0; - if (BPF_SIZE(insn->code) != BPF_DW) - return 0; /* dreg = *(u64 *)[fp - off] was a fill from the stack. * that [fp - off] slot contains scalar that needs to be @@ -1593,8 +2643,6 @@ static int backtrack_insn(struct bpf_verifier_env *env, int idx, /* scalars can only be spilled into stack */ if (insn->dst_reg != BPF_REG_FP) return 0; - if (BPF_SIZE(insn->code) != BPF_DW) - return 0; spi = (-insn->off - 1) / BPF_REG_SIZE; if (spi >= 64) { verbose(env, "BUG spi %d\n", spi); @@ -1710,7 +2758,7 @@ static void mark_all_scalars_precise(struct bpf_verifier_env *env, reg->precise = true; } for (j = 0; j < func->allocated_stack / BPF_REG_SIZE; j++) { - if (func->stack[j].slot_type[0] != STACK_SPILL) + if (!is_spilled_reg(&func->stack[j])) continue; reg = &func->stack[j].spilled_ptr; if (reg->type != SCALAR_VALUE) @@ -1734,8 +2782,7 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno, bool new_marks = false; int i, err; - if (!env->allow_ptr_leaks) - /* backtracking is root only for now */ + if (!env->bpf_capable) return 0; func = st->frame[st->curframe]; @@ -1753,7 +2800,7 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno, } while (spi >= 0) { - if (func->stack[spi].slot_type[0] != STACK_SPILL) { + if (!is_spilled_reg(&func->stack[spi])) { stack_mask = 0; break; } @@ -1778,7 +2825,7 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno, DECLARE_BITMAP(mask, 64); u32 history = st->jmp_history_cnt; - if (env->log.level & BPF_LOG_LEVEL) + if (env->log.level & BPF_LOG_LEVEL2) verbose(env, "last_idx %d first_idx %d\n", last_idx, first_idx); for (i = last_idx;;) { if (skip_first) { @@ -1852,7 +2899,7 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno, return 0; } - if (func->stack[i].slot_type[0] != STACK_SPILL) { + if (!is_spilled_reg(&func->stack[i])) { stack_mask &= ~(1ull << i); continue; } @@ -1865,11 +2912,11 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno, new_marks = true; reg->precise = true; } - if (env->log.level & BPF_LOG_LEVEL) { - print_verifier_state(env, func); - verbose(env, "parent %s regs=%x stack=%llx marks\n", + if (env->log.level & BPF_LOG_LEVEL2) { + verbose(env, "parent %s regs=%x stack=%llx marks:", new_marks ? "didn't have" : "already had", reg_mask, stack_mask); + print_verifier_state(env, func, true); } if (!reg_mask && !stack_mask) @@ -1883,7 +2930,7 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno, return 0; } -static int mark_chain_precision(struct bpf_verifier_env *env, int regno) +int mark_chain_precision(struct bpf_verifier_env *env, int regno) { return __mark_chain_precision(env, regno, -1); } @@ -1895,9 +2942,8 @@ static int mark_chain_precision_stack(struct bpf_verifier_env *env, int spi) static bool is_spillable_regtype(enum bpf_reg_type type) { - switch (type) { + switch (base_type(type)) { case PTR_TO_MAP_VALUE: - case PTR_TO_MAP_VALUE_OR_NULL: case PTR_TO_STACK: case PTR_TO_CTX: case PTR_TO_PACKET: @@ -1906,13 +2952,14 @@ static bool is_spillable_regtype(enum bpf_reg_type type) case PTR_TO_FLOW_KEYS: case CONST_PTR_TO_MAP: case PTR_TO_SOCKET: - case PTR_TO_SOCKET_OR_NULL: case PTR_TO_SOCK_COMMON: - case PTR_TO_SOCK_COMMON_OR_NULL: case PTR_TO_TCP_SOCK: - case PTR_TO_TCP_SOCK_OR_NULL: case PTR_TO_XDP_SOCK: case PTR_TO_BTF_ID: + case PTR_TO_BUF: + case PTR_TO_MEM: + case PTR_TO_FUNC: + case PTR_TO_MAP_KEY: return true; default: return false; @@ -1930,32 +2977,62 @@ static bool register_is_const(struct bpf_reg_state *reg) return reg->type == SCALAR_VALUE && tnum_is_const(reg->var_off); } +static bool __is_scalar_unbounded(struct bpf_reg_state *reg) +{ + return tnum_is_unknown(reg->var_off) && + reg->smin_value == S64_MIN && reg->smax_value == S64_MAX && + reg->umin_value == 0 && reg->umax_value == U64_MAX && + reg->s32_min_value == S32_MIN && reg->s32_max_value == S32_MAX && + reg->u32_min_value == 0 && reg->u32_max_value == U32_MAX; +} + +static bool register_is_bounded(struct bpf_reg_state *reg) +{ + return reg->type == SCALAR_VALUE && !__is_scalar_unbounded(reg); +} + +static bool __is_pointer_value(bool allow_ptr_leaks, + const struct bpf_reg_state *reg) +{ + if (allow_ptr_leaks) + return false; + + return reg->type != SCALAR_VALUE; +} + static void save_register_state(struct bpf_func_state *state, - int spi, struct bpf_reg_state *reg) + int spi, struct bpf_reg_state *reg, + int size) { int i; state->stack[spi].spilled_ptr = *reg; - state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN; + if (size == BPF_REG_SIZE) + state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN; + + for (i = BPF_REG_SIZE; i > BPF_REG_SIZE - size; i--) + state->stack[spi].slot_type[i - 1] = STACK_SPILL; - for (i = 0; i < BPF_REG_SIZE; i++) - state->stack[spi].slot_type[i] = STACK_SPILL; + /* size < 8 bytes spill */ + for (; i; i--) + scrub_spilled_slot(&state->stack[spi].slot_type[i - 1]); } -/* check_stack_read/write functions track spill/fill of registers, +/* check_stack_{read,write}_fixed_off functions track spill/fill of registers, * stack boundary and alignment are checked in check_mem_access() */ -static int check_stack_write(struct bpf_verifier_env *env, - struct bpf_func_state *state, /* func where register points to */ - int off, int size, int value_regno, int insn_idx) +static int check_stack_write_fixed_off(struct bpf_verifier_env *env, + /* stack frame we're writing to */ + struct bpf_func_state *state, + int off, int size, int value_regno, + int insn_idx) { struct bpf_func_state *cur; /* state of the current function */ int i, slot = -off - 1, spi = slot / BPF_REG_SIZE, err; u32 dst_reg = env->prog->insnsi[insn_idx].dst_reg; struct bpf_reg_state *reg = NULL; - err = realloc_func_state(state, round_up(slot + 1, BPF_REG_SIZE), - state->acquired_refs, true); + err = grow_stack_state(state, round_up(slot + 1, BPF_REG_SIZE)); if (err) return err; /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0, @@ -1971,13 +3048,27 @@ static int check_stack_write(struct bpf_verifier_env *env, cur = env->cur_state->frame[env->cur_state->curframe]; if (value_regno >= 0) reg = &cur->regs[value_regno]; + if (!env->bypass_spec_v4) { + bool sanitize = reg && is_spillable_regtype(reg->type); - if (reg && size == BPF_REG_SIZE && register_is_const(reg) && - !register_is_null(reg) && env->allow_ptr_leaks) { + for (i = 0; i < size; i++) { + if (state->stack[spi].slot_type[i] == STACK_INVALID) { + sanitize = true; + break; + } + } + + if (sanitize) + env->insn_aux_data[insn_idx].sanitize_stack_spill = true; + } + + mark_stack_slot_scratched(env, spi); + if (reg && !(off % BPF_REG_SIZE) && register_is_bounded(reg) && + !register_is_null(reg) && env->bpf_capable) { if (dst_reg != BPF_REG_FP) { /* The backtracking logic can only recognize explicit * stack slot address like [fp - 8]. Other spill of - * scalar via different register has to be conervative. + * scalar via different register has to be conservative. * Backtrack from here and mark all registers as precise * that contributed into 'reg' being a constant. */ @@ -1985,7 +3076,7 @@ static int check_stack_write(struct bpf_verifier_env *env, if (err) return err; } - save_register_state(state, spi, reg); + save_register_state(state, spi, reg, size); } else if (reg && is_spillable_regtype(reg->type)) { /* register containing pointer is being spilled into stack */ if (size != BPF_REG_SIZE) { @@ -1993,57 +3084,20 @@ static int check_stack_write(struct bpf_verifier_env *env, verbose(env, "invalid size of register spill\n"); return -EACCES; } - if (state != cur && reg->type == PTR_TO_STACK) { verbose(env, "cannot spill pointers to stack into stack frame of the caller\n"); return -EINVAL; } - - if (!env->allow_ptr_leaks) { - bool sanitize = false; - - if (state->stack[spi].slot_type[0] == STACK_SPILL && - register_is_const(&state->stack[spi].spilled_ptr)) - sanitize = true; - for (i = 0; i < BPF_REG_SIZE; i++) - if (state->stack[spi].slot_type[i] == STACK_MISC) { - sanitize = true; - break; - } - if (sanitize) { - int *poff = &env->insn_aux_data[insn_idx].sanitize_stack_off; - int soff = (-spi - 1) * BPF_REG_SIZE; - - /* detected reuse of integer stack slot with a pointer - * which means either llvm is reusing stack slot or - * an attacker is trying to exploit CVE-2018-3639 - * (speculative store bypass) - * Have to sanitize that slot with preemptive - * store of zero. - */ - if (*poff && *poff != soff) { - /* disallow programs where single insn stores - * into two different stack slots, since verifier - * cannot sanitize them - */ - verbose(env, - "insn %d cannot access two stack slots fp%d and fp%d", - insn_idx, *poff, soff); - return -EINVAL; - } - *poff = soff; - } - } - save_register_state(state, spi, reg); + save_register_state(state, spi, reg, size); } else { u8 type = STACK_MISC; /* regular write of data into stack destroys any spilled ptr */ state->stack[spi].spilled_ptr.type = NOT_INIT; /* Mark slots as STACK_MISC if they belonged to spilled ptr. */ - if (state->stack[spi].slot_type[0] == STACK_SPILL) + if (is_spilled_reg(&state->stack[spi])) for (i = 0; i < BPF_REG_SIZE; i++) - state->stack[spi].slot_type[i] = STACK_MISC; + scrub_spilled_slot(&state->stack[spi].slot_type[i]); /* only mark the slot as written if all 8 bytes were written * otherwise read propagation may incorrectly stop too soon @@ -2073,120 +3127,407 @@ static int check_stack_write(struct bpf_verifier_env *env, return 0; } -static int check_stack_read(struct bpf_verifier_env *env, - struct bpf_func_state *reg_state /* func where register points to */, - int off, int size, int value_regno) +/* Write the stack: 'stack[ptr_regno + off] = value_regno'. 'ptr_regno' is + * known to contain a variable offset. + * This function checks whether the write is permitted and conservatively + * tracks the effects of the write, considering that each stack slot in the + * dynamic range is potentially written to. + * + * 'off' includes 'regno->off'. + * 'value_regno' can be -1, meaning that an unknown value is being written to + * the stack. + * + * Spilled pointers in range are not marked as written because we don't know + * what's going to be actually written. This means that read propagation for + * future reads cannot be terminated by this write. + * + * For privileged programs, uninitialized stack slots are considered + * initialized by this write (even though we don't know exactly what offsets + * are going to be written to). The idea is that we don't want the verifier to + * reject future reads that access slots written to through variable offsets. + */ +static int check_stack_write_var_off(struct bpf_verifier_env *env, + /* func where register points to */ + struct bpf_func_state *state, + int ptr_regno, int off, int size, + int value_regno, int insn_idx) +{ + struct bpf_func_state *cur; /* state of the current function */ + int min_off, max_off; + int i, err; + struct bpf_reg_state *ptr_reg = NULL, *value_reg = NULL; + bool writing_zero = false; + /* set if the fact that we're writing a zero is used to let any + * stack slots remain STACK_ZERO + */ + bool zero_used = false; + + cur = env->cur_state->frame[env->cur_state->curframe]; + ptr_reg = &cur->regs[ptr_regno]; + min_off = ptr_reg->smin_value + off; + max_off = ptr_reg->smax_value + off + size; + if (value_regno >= 0) + value_reg = &cur->regs[value_regno]; + if (value_reg && register_is_null(value_reg)) + writing_zero = true; + + err = grow_stack_state(state, round_up(-min_off, BPF_REG_SIZE)); + if (err) + return err; + + + /* Variable offset writes destroy any spilled pointers in range. */ + for (i = min_off; i < max_off; i++) { + u8 new_type, *stype; + int slot, spi; + + slot = -i - 1; + spi = slot / BPF_REG_SIZE; + stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE]; + mark_stack_slot_scratched(env, spi); + + if (!env->allow_ptr_leaks + && *stype != NOT_INIT + && *stype != SCALAR_VALUE) { + /* Reject the write if there's are spilled pointers in + * range. If we didn't reject here, the ptr status + * would be erased below (even though not all slots are + * actually overwritten), possibly opening the door to + * leaks. + */ + verbose(env, "spilled ptr in range of var-offset stack write; insn %d, ptr off: %d", + insn_idx, i); + return -EINVAL; + } + + /* Erase all spilled pointers. */ + state->stack[spi].spilled_ptr.type = NOT_INIT; + + /* Update the slot type. */ + new_type = STACK_MISC; + if (writing_zero && *stype == STACK_ZERO) { + new_type = STACK_ZERO; + zero_used = true; + } + /* If the slot is STACK_INVALID, we check whether it's OK to + * pretend that it will be initialized by this write. The slot + * might not actually be written to, and so if we mark it as + * initialized future reads might leak uninitialized memory. + * For privileged programs, we will accept such reads to slots + * that may or may not be written because, if we're reject + * them, the error would be too confusing. + */ + if (*stype == STACK_INVALID && !env->allow_uninit_stack) { + verbose(env, "uninit stack in range of var-offset write prohibited for !root; insn %d, off: %d", + insn_idx, i); + return -EINVAL; + } + *stype = new_type; + } + if (zero_used) { + /* backtracking doesn't work for STACK_ZERO yet. */ + err = mark_chain_precision(env, value_regno); + if (err) + return err; + } + return 0; +} + +/* When register 'dst_regno' is assigned some values from stack[min_off, + * max_off), we set the register's type according to the types of the + * respective stack slots. If all the stack values are known to be zeros, then + * so is the destination reg. Otherwise, the register is considered to be + * SCALAR. This function does not deal with register filling; the caller must + * ensure that all spilled registers in the stack range have been marked as + * read. + */ +static void mark_reg_stack_read(struct bpf_verifier_env *env, + /* func where src register points to */ + struct bpf_func_state *ptr_state, + int min_off, int max_off, int dst_regno) { struct bpf_verifier_state *vstate = env->cur_state; struct bpf_func_state *state = vstate->frame[vstate->curframe]; - int i, slot = -off - 1, spi = slot / BPF_REG_SIZE; - struct bpf_reg_state *reg; + int i, slot, spi; u8 *stype; + int zeros = 0; - if (reg_state->allocated_stack <= slot) { - verbose(env, "invalid read from stack off %d+0 size %d\n", - off, size); - return -EACCES; + for (i = min_off; i < max_off; i++) { + slot = -i - 1; + spi = slot / BPF_REG_SIZE; + stype = ptr_state->stack[spi].slot_type; + if (stype[slot % BPF_REG_SIZE] != STACK_ZERO) + break; + zeros++; } + if (zeros == max_off - min_off) { + /* any access_size read into register is zero extended, + * so the whole register == const_zero + */ + __mark_reg_const_zero(&state->regs[dst_regno]); + /* backtracking doesn't support STACK_ZERO yet, + * so mark it precise here, so that later + * backtracking can stop here. + * Backtracking may not need this if this register + * doesn't participate in pointer adjustment. + * Forward propagation of precise flag is not + * necessary either. This mark is only to stop + * backtracking. Any register that contributed + * to const 0 was marked precise before spill. + */ + state->regs[dst_regno].precise = true; + } else { + /* have read misc data from the stack */ + mark_reg_unknown(env, state->regs, dst_regno); + } + state->regs[dst_regno].live |= REG_LIVE_WRITTEN; +} + +/* Read the stack at 'off' and put the results into the register indicated by + * 'dst_regno'. It handles reg filling if the addressed stack slot is a + * spilled reg. + * + * 'dst_regno' can be -1, meaning that the read value is not going to a + * register. + * + * The access is assumed to be within the current stack bounds. + */ +static int check_stack_read_fixed_off(struct bpf_verifier_env *env, + /* func where src register points to */ + struct bpf_func_state *reg_state, + int off, int size, int dst_regno) +{ + struct bpf_verifier_state *vstate = env->cur_state; + struct bpf_func_state *state = vstate->frame[vstate->curframe]; + int i, slot = -off - 1, spi = slot / BPF_REG_SIZE; + struct bpf_reg_state *reg; + u8 *stype, type; + stype = reg_state->stack[spi].slot_type; reg = ®_state->stack[spi].spilled_ptr; - if (stype[0] == STACK_SPILL) { - if (size != BPF_REG_SIZE) { + if (is_spilled_reg(®_state->stack[spi])) { + u8 spill_size = 1; + + for (i = BPF_REG_SIZE - 1; i > 0 && stype[i - 1] == STACK_SPILL; i--) + spill_size++; + + if (size != BPF_REG_SIZE || spill_size != BPF_REG_SIZE) { if (reg->type != SCALAR_VALUE) { verbose_linfo(env, env->insn_idx, "; "); verbose(env, "invalid size of register fill\n"); return -EACCES; } - if (value_regno >= 0) { - mark_reg_unknown(env, state->regs, value_regno); - state->regs[value_regno].live |= REG_LIVE_WRITTEN; - } + mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64); - return 0; - } - for (i = 1; i < BPF_REG_SIZE; i++) { - if (stype[(slot - i) % BPF_REG_SIZE] != STACK_SPILL) { - verbose(env, "corrupted spill memory\n"); - return -EACCES; + if (dst_regno < 0) + return 0; + + if (!(off % BPF_REG_SIZE) && size == spill_size) { + /* The earlier check_reg_arg() has decided the + * subreg_def for this insn. Save it first. + */ + s32 subreg_def = state->regs[dst_regno].subreg_def; + + state->regs[dst_regno] = *reg; + state->regs[dst_regno].subreg_def = subreg_def; + } else { + for (i = 0; i < size; i++) { + type = stype[(slot - i) % BPF_REG_SIZE]; + if (type == STACK_SPILL) + continue; + if (type == STACK_MISC) + continue; + verbose(env, "invalid read from stack off %d+%d size %d\n", + off, i, size); + return -EACCES; + } + mark_reg_unknown(env, state->regs, dst_regno); } + state->regs[dst_regno].live |= REG_LIVE_WRITTEN; + return 0; } - if (value_regno >= 0) { + if (dst_regno >= 0) { /* restore register state from stack */ - state->regs[value_regno] = *reg; + state->regs[dst_regno] = *reg; /* mark reg as written since spilled pointer state likely * has its liveness marks cleared by is_state_visited() * which resets stack/reg liveness for state transitions */ - state->regs[value_regno].live |= REG_LIVE_WRITTEN; + state->regs[dst_regno].live |= REG_LIVE_WRITTEN; + } else if (__is_pointer_value(env->allow_ptr_leaks, reg)) { + /* If dst_regno==-1, the caller is asking us whether + * it is acceptable to use this value as a SCALAR_VALUE + * (e.g. for XADD). + * We must not allow unprivileged callers to do that + * with spilled pointers. + */ + verbose(env, "leaking pointer from stack off %d\n", + off); + return -EACCES; } mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64); } else { - int zeros = 0; - for (i = 0; i < size; i++) { - if (stype[(slot - i) % BPF_REG_SIZE] == STACK_MISC) + type = stype[(slot - i) % BPF_REG_SIZE]; + if (type == STACK_MISC) continue; - if (stype[(slot - i) % BPF_REG_SIZE] == STACK_ZERO) { - zeros++; + if (type == STACK_ZERO) continue; - } verbose(env, "invalid read from stack off %d+%d size %d\n", off, i, size); return -EACCES; } mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64); - if (value_regno >= 0) { - if (zeros == size) { - /* any size read into register is zero extended, - * so the whole register == const_zero - */ - __mark_reg_const_zero(&state->regs[value_regno]); - /* backtracking doesn't support STACK_ZERO yet, - * so mark it precise here, so that later - * backtracking can stop here. - * Backtracking may not need this if this register - * doesn't participate in pointer adjustment. - * Forward propagation of precise flag is not - * necessary either. This mark is only to stop - * backtracking. Any register that contributed - * to const 0 was marked precise before spill. - */ - state->regs[value_regno].precise = true; - } else { - /* have read misc data from the stack */ - mark_reg_unknown(env, state->regs, value_regno); - } - state->regs[value_regno].live |= REG_LIVE_WRITTEN; - } + if (dst_regno >= 0) + mark_reg_stack_read(env, reg_state, off, off + size, dst_regno); } return 0; } -static int check_stack_access(struct bpf_verifier_env *env, - const struct bpf_reg_state *reg, - int off, int size) +enum bpf_access_src { + ACCESS_DIRECT = 1, /* the access is performed by an instruction */ + ACCESS_HELPER = 2, /* the access is performed by a helper */ +}; + +static int check_stack_range_initialized(struct bpf_verifier_env *env, + int regno, int off, int access_size, + bool zero_size_allowed, + enum bpf_access_src type, + struct bpf_call_arg_meta *meta); + +static struct bpf_reg_state *reg_state(struct bpf_verifier_env *env, int regno) { - /* Stack accesses must be at a fixed offset, so that we - * can determine what type of data were returned. See - * check_stack_read(). + return cur_regs(env) + regno; +} + +/* Read the stack at 'ptr_regno + off' and put the result into the register + * 'dst_regno'. + * 'off' includes the pointer register's fixed offset(i.e. 'ptr_regno.off'), + * but not its variable offset. + * 'size' is assumed to be <= reg size and the access is assumed to be aligned. + * + * As opposed to check_stack_read_fixed_off, this function doesn't deal with + * filling registers (i.e. reads of spilled register cannot be detected when + * the offset is not fixed). We conservatively mark 'dst_regno' as containing + * SCALAR_VALUE. That's why we assert that the 'ptr_regno' has a variable + * offset; for a fixed offset check_stack_read_fixed_off should be used + * instead. + */ +static int check_stack_read_var_off(struct bpf_verifier_env *env, + int ptr_regno, int off, int size, int dst_regno) +{ + /* The state of the source register. */ + struct bpf_reg_state *reg = reg_state(env, ptr_regno); + struct bpf_func_state *ptr_state = func(env, reg); + int err; + int min_off, max_off; + + /* Note that we pass a NULL meta, so raw access will not be permitted. */ - if (!tnum_is_const(reg->var_off)) { + err = check_stack_range_initialized(env, ptr_regno, off, size, + false, ACCESS_DIRECT, NULL); + if (err) + return err; + + min_off = reg->smin_value + off; + max_off = reg->smax_value + off; + mark_reg_stack_read(env, ptr_state, min_off, max_off + size, dst_regno); + return 0; +} + +/* check_stack_read dispatches to check_stack_read_fixed_off or + * check_stack_read_var_off. + * + * The caller must ensure that the offset falls within the allocated stack + * bounds. + * + * 'dst_regno' is a register which will receive the value from the stack. It + * can be -1, meaning that the read value is not going to a register. + */ +static int check_stack_read(struct bpf_verifier_env *env, + int ptr_regno, int off, int size, + int dst_regno) +{ + struct bpf_reg_state *reg = reg_state(env, ptr_regno); + struct bpf_func_state *state = func(env, reg); + int err; + /* Some accesses are only permitted with a static offset. */ + bool var_off = !tnum_is_const(reg->var_off); + + /* The offset is required to be static when reads don't go to a + * register, in order to not leak pointers (see + * check_stack_read_fixed_off). + */ + if (dst_regno < 0 && var_off) { char tn_buf[48]; tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); - verbose(env, "variable stack access var_off=%s off=%d size=%d\n", + verbose(env, "variable offset stack pointer cannot be passed into helper function; var_off=%s off=%d size=%d\n", tn_buf, off, size); return -EACCES; } + /* Variable offset is prohibited for unprivileged mode for simplicity + * since it requires corresponding support in Spectre masking for stack + * ALU. See also retrieve_ptr_limit(). + */ + if (!env->bypass_spec_v1 && var_off) { + char tn_buf[48]; - if (off >= 0 || off < -MAX_BPF_STACK) { - verbose(env, "invalid stack off=%d size=%d\n", off, size); + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose(env, "R%d variable offset stack access prohibited for !root, var_off=%s\n", + ptr_regno, tn_buf); return -EACCES; } - return 0; + if (!var_off) { + off += reg->var_off.value; + err = check_stack_read_fixed_off(env, state, off, size, + dst_regno); + } else { + /* Variable offset stack reads need more conservative handling + * than fixed offset ones. Note that dst_regno >= 0 on this + * branch. + */ + err = check_stack_read_var_off(env, ptr_regno, off, size, + dst_regno); + } + return err; +} + + +/* check_stack_write dispatches to check_stack_write_fixed_off or + * check_stack_write_var_off. + * + * 'ptr_regno' is the register used as a pointer into the stack. + * 'off' includes 'ptr_regno->off', but not its variable offset (if any). + * 'value_regno' is the register whose value we're writing to the stack. It can + * be -1, meaning that we're not writing from a register. + * + * The caller must ensure that the offset falls within the maximum stack size. + */ +static int check_stack_write(struct bpf_verifier_env *env, + int ptr_regno, int off, int size, + int value_regno, int insn_idx) +{ + struct bpf_reg_state *reg = reg_state(env, ptr_regno); + struct bpf_func_state *state = func(env, reg); + int err; + + if (tnum_is_const(reg->var_off)) { + off += reg->var_off.value; + err = check_stack_write_fixed_off(env, state, off, size, + value_regno, insn_idx); + } else { + /* Variable offset stack reads need more conservative handling + * than fixed offset ones. + */ + err = check_stack_write_var_off(env, state, + ptr_regno, off, size, + value_regno, insn_idx); + } + return err; } static int check_map_access_type(struct bpf_verifier_env *env, u32 regno, @@ -2211,39 +3552,57 @@ static int check_map_access_type(struct bpf_verifier_env *env, u32 regno, return 0; } -/* check read/write into map element returned by bpf_map_lookup_elem() */ -static int __check_map_access(struct bpf_verifier_env *env, u32 regno, int off, - int size, bool zero_size_allowed) +/* check read/write into memory region (e.g., map value, ringbuf sample, etc) */ +static int __check_mem_access(struct bpf_verifier_env *env, int regno, + int off, int size, u32 mem_size, + bool zero_size_allowed) { - struct bpf_reg_state *regs = cur_regs(env); - struct bpf_map *map = regs[regno].map_ptr; + bool size_ok = size > 0 || (size == 0 && zero_size_allowed); + struct bpf_reg_state *reg; + + if (off >= 0 && size_ok && (u64)off + size <= mem_size) + return 0; - if (off < 0 || size < 0 || (size == 0 && !zero_size_allowed) || - off + size > map->value_size) { + reg = &cur_regs(env)[regno]; + switch (reg->type) { + case PTR_TO_MAP_KEY: + verbose(env, "invalid access to map key, key_size=%d off=%d size=%d\n", + mem_size, off, size); + break; + case PTR_TO_MAP_VALUE: verbose(env, "invalid access to map value, value_size=%d off=%d size=%d\n", - map->value_size, off, size); - return -EACCES; + mem_size, off, size); + break; + case PTR_TO_PACKET: + case PTR_TO_PACKET_META: + case PTR_TO_PACKET_END: + verbose(env, "invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n", + off, size, regno, reg->id, off, mem_size); + break; + case PTR_TO_MEM: + default: + verbose(env, "invalid access to memory, mem_size=%u off=%d size=%d\n", + mem_size, off, size); } - return 0; + + return -EACCES; } -/* check read/write into a map element with possible variable offset */ -static int check_map_access(struct bpf_verifier_env *env, u32 regno, - int off, int size, bool zero_size_allowed) +/* check read/write into a memory region with possible variable offset */ +static int check_mem_region_access(struct bpf_verifier_env *env, u32 regno, + int off, int size, u32 mem_size, + bool zero_size_allowed) { struct bpf_verifier_state *vstate = env->cur_state; struct bpf_func_state *state = vstate->frame[vstate->curframe]; struct bpf_reg_state *reg = &state->regs[regno]; int err; - /* We may have adjusted the register to this map value, so we + /* We may have adjusted the register pointing to memory region, so we * need to try adding each of min_value and max_value to off * to make sure our theoretical access will be safe. - */ - if (env->log.level & BPF_LOG_LEVEL) - print_verifier_state(env, state); - - /* The minimum value is only important with signed + * + * The minimum value is only important with signed * comparisons where we can't assume the floor of a * value is 0. If we are using signed variables for our * index'es we need to make sure that whatever we use @@ -2257,10 +3616,10 @@ static int check_map_access(struct bpf_verifier_env *env, u32 regno, regno); return -EACCES; } - err = __check_map_access(env, regno, reg->smin_value + off, size, - zero_size_allowed); + err = __check_mem_access(env, regno, reg->smin_value + off, size, + mem_size, zero_size_allowed); if (err) { - verbose(env, "R%d min value is outside of the array range\n", + verbose(env, "R%d min value is outside of the allowed memory range\n", regno); return err; } @@ -2270,18 +3629,204 @@ static int check_map_access(struct bpf_verifier_env *env, u32 regno, * If reg->umax_value + off could overflow, treat that as unbounded too. */ if (reg->umax_value >= BPF_MAX_VAR_OFF) { - verbose(env, "R%d unbounded memory access, make sure to bounds check any array access into a map\n", + verbose(env, "R%d unbounded memory access, make sure to bounds check any such access\n", regno); return -EACCES; } - err = __check_map_access(env, regno, reg->umax_value + off, size, - zero_size_allowed); - if (err) - verbose(env, "R%d max value is outside of the array range\n", + err = __check_mem_access(env, regno, reg->umax_value + off, size, + mem_size, zero_size_allowed); + if (err) { + verbose(env, "R%d max value is outside of the allowed memory range\n", regno); + return err; + } + + return 0; +} + +static int __check_ptr_off_reg(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, int regno, + bool fixed_off_ok) +{ + /* Access to this pointer-typed register or passing it to a helper + * is only allowed in its original, unmodified form. + */ + + if (reg->off < 0) { + verbose(env, "negative offset %s ptr R%d off=%d disallowed\n", + reg_type_str(env, reg->type), regno, reg->off); + return -EACCES; + } + + if (!fixed_off_ok && reg->off) { + verbose(env, "dereference of modified %s ptr R%d off=%d disallowed\n", + reg_type_str(env, reg->type), regno, reg->off); + return -EACCES; + } + + if (!tnum_is_const(reg->var_off) || reg->var_off.value) { + char tn_buf[48]; + + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose(env, "variable %s access var_off=%s disallowed\n", + reg_type_str(env, reg->type), tn_buf); + return -EACCES; + } + + return 0; +} + +int check_ptr_off_reg(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, int regno) +{ + return __check_ptr_off_reg(env, reg, regno, false); +} + +static int map_kptr_match_type(struct bpf_verifier_env *env, + struct bpf_map_value_off_desc *off_desc, + struct bpf_reg_state *reg, u32 regno) +{ + const char *targ_name = kernel_type_name(off_desc->kptr.btf, off_desc->kptr.btf_id); + int perm_flags = PTR_MAYBE_NULL; + const char *reg_name = ""; - if (map_value_has_spin_lock(reg->map_ptr)) { - u32 lock = reg->map_ptr->spin_lock_off; + /* Only unreferenced case accepts untrusted pointers */ + if (off_desc->type == BPF_KPTR_UNREF) + perm_flags |= PTR_UNTRUSTED; + + if (base_type(reg->type) != PTR_TO_BTF_ID || (type_flag(reg->type) & ~perm_flags)) + goto bad_type; + + if (!btf_is_kernel(reg->btf)) { + verbose(env, "R%d must point to kernel BTF\n", regno); + return -EINVAL; + } + /* We need to verify reg->type and reg->btf, before accessing reg->btf */ + reg_name = kernel_type_name(reg->btf, reg->btf_id); + + /* For ref_ptr case, release function check should ensure we get one + * referenced PTR_TO_BTF_ID, and that its fixed offset is 0. For the + * normal store of unreferenced kptr, we must ensure var_off is zero. + * Since ref_ptr cannot be accessed directly by BPF insns, checks for + * reg->off and reg->ref_obj_id are not needed here. + */ + if (__check_ptr_off_reg(env, reg, regno, true)) + return -EACCES; + + /* A full type match is needed, as BTF can be vmlinux or module BTF, and + * we also need to take into account the reg->off. + * + * We want to support cases like: + * + * struct foo { + * struct bar br; + * struct baz bz; + * }; + * + * struct foo *v; + * v = func(); // PTR_TO_BTF_ID + * val->foo = v; // reg->off is zero, btf and btf_id match type + * val->bar = &v->br; // reg->off is still zero, but we need to retry with + * // first member type of struct after comparison fails + * val->baz = &v->bz; // reg->off is non-zero, so struct needs to be walked + * // to match type + * + * In the kptr_ref case, check_func_arg_reg_off already ensures reg->off + * is zero. We must also ensure that btf_struct_ids_match does not walk + * the struct to match type against first member of struct, i.e. reject + * second case from above. Hence, when type is BPF_KPTR_REF, we set + * strict mode to true for type match. + */ + if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, reg->off, + off_desc->kptr.btf, off_desc->kptr.btf_id, + off_desc->type == BPF_KPTR_REF)) + goto bad_type; + return 0; +bad_type: + verbose(env, "invalid kptr access, R%d type=%s%s ", regno, + reg_type_str(env, reg->type), reg_name); + verbose(env, "expected=%s%s", reg_type_str(env, PTR_TO_BTF_ID), targ_name); + if (off_desc->type == BPF_KPTR_UNREF) + verbose(env, " or %s%s\n", reg_type_str(env, PTR_TO_BTF_ID | PTR_UNTRUSTED), + targ_name); + else + verbose(env, "\n"); + return -EINVAL; +} + +static int check_map_kptr_access(struct bpf_verifier_env *env, u32 regno, + int value_regno, int insn_idx, + struct bpf_map_value_off_desc *off_desc) +{ + struct bpf_insn *insn = &env->prog->insnsi[insn_idx]; + int class = BPF_CLASS(insn->code); + struct bpf_reg_state *val_reg; + + /* Things we already checked for in check_map_access and caller: + * - Reject cases where variable offset may touch kptr + * - size of access (must be BPF_DW) + * - tnum_is_const(reg->var_off) + * - off_desc->offset == off + reg->var_off.value + */ + /* Only BPF_[LDX,STX,ST] | BPF_MEM | BPF_DW is supported */ + if (BPF_MODE(insn->code) != BPF_MEM) { + verbose(env, "kptr in map can only be accessed using BPF_MEM instruction mode\n"); + return -EACCES; + } + + /* We only allow loading referenced kptr, since it will be marked as + * untrusted, similar to unreferenced kptr. + */ + if (class != BPF_LDX && off_desc->type == BPF_KPTR_REF) { + verbose(env, "store to referenced kptr disallowed\n"); + return -EACCES; + } + + if (class == BPF_LDX) { + val_reg = reg_state(env, value_regno); + /* We can simply mark the value_regno receiving the pointer + * value from map as PTR_TO_BTF_ID, with the correct type. + */ + mark_btf_ld_reg(env, cur_regs(env), value_regno, PTR_TO_BTF_ID, off_desc->kptr.btf, + off_desc->kptr.btf_id, PTR_MAYBE_NULL | PTR_UNTRUSTED); + /* For mark_ptr_or_null_reg */ + val_reg->id = ++env->id_gen; + } else if (class == BPF_STX) { + val_reg = reg_state(env, value_regno); + if (!register_is_null(val_reg) && + map_kptr_match_type(env, off_desc, val_reg, value_regno)) + return -EACCES; + } else if (class == BPF_ST) { + if (insn->imm) { + verbose(env, "BPF_ST imm must be 0 when storing to kptr at off=%u\n", + off_desc->offset); + return -EACCES; + } + } else { + verbose(env, "kptr in map can only be accessed using BPF_LDX/BPF_STX/BPF_ST\n"); + return -EACCES; + } + return 0; +} + +/* check read/write into a map element with possible variable offset */ +static int check_map_access(struct bpf_verifier_env *env, u32 regno, + int off, int size, bool zero_size_allowed, + enum bpf_access_src src) +{ + struct bpf_verifier_state *vstate = env->cur_state; + struct bpf_func_state *state = vstate->frame[vstate->curframe]; + struct bpf_reg_state *reg = &state->regs[regno]; + struct bpf_map *map = reg->map_ptr; + int err; + + err = check_mem_region_access(env, regno, off, size, map->value_size, + zero_size_allowed); + if (err) + return err; + + if (map_value_has_spin_lock(map)) { + u32 lock = map->spin_lock_off; /* if any part of struct bpf_spin_lock can be touched by * load/store reject this program. @@ -2294,6 +3839,45 @@ static int check_map_access(struct bpf_verifier_env *env, u32 regno, return -EACCES; } } + if (map_value_has_timer(map)) { + u32 t = map->timer_off; + + if (reg->smin_value + off < t + sizeof(struct bpf_timer) && + t < reg->umax_value + off + size) { + verbose(env, "bpf_timer cannot be accessed directly by load/store\n"); + return -EACCES; + } + } + if (map_value_has_kptrs(map)) { + struct bpf_map_value_off *tab = map->kptr_off_tab; + int i; + + for (i = 0; i < tab->nr_off; i++) { + u32 p = tab->off[i].offset; + + if (reg->smin_value + off < p + sizeof(u64) && + p < reg->umax_value + off + size) { + if (src != ACCESS_DIRECT) { + verbose(env, "kptr cannot be accessed indirectly by helper\n"); + return -EACCES; + } + if (!tnum_is_const(reg->var_off)) { + verbose(env, "kptr access cannot have variable offset\n"); + return -EACCES; + } + if (p != off + reg->var_off.value) { + verbose(env, "kptr access misaligned expected=%u off=%llu\n", + p, off + reg->var_off.value); + return -EACCES; + } + if (size != bpf_size_to_bytes(BPF_DW)) { + verbose(env, "kptr access size must be BPF_DW\n"); + return -EACCES; + } + break; + } + } + } return err; } @@ -2303,7 +3887,9 @@ static bool may_access_direct_pkt_data(struct bpf_verifier_env *env, const struct bpf_call_arg_meta *meta, enum bpf_access_type t) { - switch (env->prog->type) { + enum bpf_prog_type prog_type = resolve_prog_type(env->prog); + + switch (prog_type) { /* Program types only with direct read access go here! */ case BPF_PROG_TYPE_LWT_IN: case BPF_PROG_TYPE_LWT_OUT: @@ -2313,7 +3899,7 @@ static bool may_access_direct_pkt_data(struct bpf_verifier_env *env, case BPF_PROG_TYPE_CGROUP_SKB: if (t == BPF_WRITE) return false; - /* fallthrough */ + fallthrough; /* Program types with direct read + write access go here! */ case BPF_PROG_TYPE_SCHED_CLS: @@ -2339,21 +3925,6 @@ static bool may_access_direct_pkt_data(struct bpf_verifier_env *env, } } -static int __check_packet_access(struct bpf_verifier_env *env, u32 regno, - int off, int size, bool zero_size_allowed) -{ - struct bpf_reg_state *regs = cur_regs(env); - struct bpf_reg_state *reg = ®s[regno]; - - if (off < 0 || size < 0 || (size == 0 && !zero_size_allowed) || - (u64)off + size > reg->range) { - verbose(env, "invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n", - off, size, regno, reg->id, reg->off, reg->range); - return -EACCES; - } - return 0; -} - static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off, int size, bool zero_size_allowed) { @@ -2374,16 +3945,19 @@ static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off, regno); return -EACCES; } - err = __check_packet_access(env, regno, off, size, zero_size_allowed); + + err = reg->range < 0 ? -EINVAL : + __check_mem_access(env, regno, off, size, reg->range, + zero_size_allowed); if (err) { verbose(env, "R%d offset is outside of the packet\n", regno); return err; } - /* __check_packet_access has made sure "off + size - 1" is within u16. + /* __check_mem_access has made sure "off + size - 1" is within u16. * reg->umax_value can't be bigger than MAX_PACKET_OFF which is 0xffff, * otherwise find_good_pkt_pointers would have refused to set range info - * that __check_packet_access would have rejected this pkt access. + * that __check_mem_access would have rejected this pkt access. * Therefore, "off + reg->umax_value + size - 1" won't overflow u32. */ env->prog->aux->max_pkt_offset = @@ -2396,7 +3970,7 @@ static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off, /* check access to 'struct bpf_context' fields. Supports fixed offsets only */ static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size, enum bpf_access_type t, enum bpf_reg_type *reg_type, - u32 *btf_id) + struct btf **btf, u32 *btf_id) { struct bpf_insn_access_aux info = { .reg_type = *reg_type, @@ -2414,10 +3988,12 @@ static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, */ *reg_type = info.reg_type; - if (*reg_type == PTR_TO_BTF_ID) + if (base_type(*reg_type) == PTR_TO_BTF_ID) { + *btf = info.btf; *btf_id = info.btf_id; - else + } else { env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size; + } /* remember the offset of last byte accessed in ctx */ if (env->prog->aux->max_ctx_offset < off + size) env->prog->aux->max_ctx_offset = off + size; @@ -2480,25 +4056,11 @@ static int check_sock_access(struct bpf_verifier_env *env, int insn_idx, } verbose(env, "R%d invalid %s access off=%d size=%d\n", - regno, reg_type_str[reg->type], off, size); + regno, reg_type_str(env, reg->type), off, size); return -EACCES; } -static bool __is_pointer_value(bool allow_ptr_leaks, - const struct bpf_reg_state *reg) -{ - if (allow_ptr_leaks) - return false; - - return reg->type != SCALAR_VALUE; -} - -static struct bpf_reg_state *reg_state(struct bpf_verifier_env *env, int regno) -{ - return cur_regs(env) + regno; -} - static bool is_pointer_value(struct bpf_verifier_env *env, int regno) { return __is_pointer_value(env->allow_ptr_leaks, reg_state(env, regno)); @@ -2609,6 +4171,9 @@ static int check_ptr_alignment(struct bpf_verifier_env *env, case PTR_TO_FLOW_KEYS: pointer_desc = "flow keys "; break; + case PTR_TO_MAP_KEY: + pointer_desc = "key "; + break; case PTR_TO_MAP_VALUE: pointer_desc = "value "; break; @@ -2617,8 +4182,8 @@ static int check_ptr_alignment(struct bpf_verifier_env *env, break; case PTR_TO_STACK: pointer_desc = "stack "; - /* The stack spill tracking logic in check_stack_write() - * and check_stack_read() relies on stack accesses being + /* The stack spill tracking logic in check_stack_write_fixed_off() + * and check_stack_read_fixed_off() relies on stack accesses being * aligned. */ strict = true; @@ -2667,10 +4232,37 @@ static int check_max_stack_depth(struct bpf_verifier_env *env) int depth = 0, frame = 0, idx = 0, i = 0, subprog_end; struct bpf_subprog_info *subprog = env->subprog_info; struct bpf_insn *insn = env->prog->insnsi; + bool tail_call_reachable = false; int ret_insn[MAX_CALL_FRAMES]; int ret_prog[MAX_CALL_FRAMES]; + int j; process_func: + /* protect against potential stack overflow that might happen when + * bpf2bpf calls get combined with tailcalls. Limit the caller's stack + * depth for such case down to 256 so that the worst case scenario + * would result in 8k stack size (32 which is tailcall limit * 256 = + * 8k). + * + * To get the idea what might happen, see an example: + * func1 -> sub rsp, 128 + * subfunc1 -> sub rsp, 256 + * tailcall1 -> add rsp, 256 + * func2 -> sub rsp, 192 (total stack size = 128 + 192 = 320) + * subfunc2 -> sub rsp, 64 + * subfunc22 -> sub rsp, 128 + * tailcall2 -> add rsp, 128 + * func3 -> sub rsp, 32 (total stack size 128 + 192 + 64 + 32 = 416) + * + * tailcall will unwind the current stack frame but it will not get rid + * of caller's stack as shown on the example above. + */ + if (idx && subprog[idx].has_tail_call && depth >= 256) { + verbose(env, + "tail_calls are not allowed when call stack of previous frames is %d bytes. Too large\n", + depth); + return -EACCES; + } /* round up to 32-bytes, since this is granularity * of interpreter stack size */ @@ -2683,22 +4275,35 @@ process_func: continue_func: subprog_end = subprog[idx + 1].start; for (; i < subprog_end; i++) { - if (insn[i].code != (BPF_JMP | BPF_CALL)) - continue; - if (insn[i].src_reg != BPF_PSEUDO_CALL) + int next_insn; + + if (!bpf_pseudo_call(insn + i) && !bpf_pseudo_func(insn + i)) continue; /* remember insn and function to return to */ ret_insn[frame] = i + 1; ret_prog[frame] = idx; /* find the callee */ - i = i + insn[i].imm + 1; - idx = find_subprog(env, i); + next_insn = i + insn[i].imm + 1; + idx = find_subprog(env, next_insn); if (idx < 0) { WARN_ONCE(1, "verifier bug. No program starts at insn %d\n", - i); + next_insn); return -EFAULT; } + if (subprog[idx].is_async_cb) { + if (subprog[idx].has_tail_call) { + verbose(env, "verifier bug. subprog has tail_call and async cb\n"); + return -EFAULT; + } + /* async callbacks don't increase bpf prog stack size */ + continue; + } + i = next_insn; + + if (subprog[idx].has_tail_call) + tail_call_reachable = true; + frame++; if (frame >= MAX_CALL_FRAMES) { verbose(env, "the call stack of %d frames is too deep !\n", @@ -2707,6 +4312,17 @@ continue_func: } goto process_func; } + /* if tail call got detected across bpf2bpf calls then mark each of the + * currently present subprog frames as tail call reachable subprogs; + * this info will be utilized by JIT so that we will be preserving the + * tail call counter throughout bpf2bpf calls combined with tailcalls + */ + if (tail_call_reachable) + for (j = 0; j < frame; j++) + subprog[ret_prog[j]].tail_call_reachable = true; + if (subprog[0].tail_call_reachable) + env->prog->aux->tail_call_reachable = true; + /* end of for() loop means the last insn of the 'subprog' * was reached. Doesn't matter whether it was JA or EXIT */ @@ -2735,24 +4351,24 @@ static int get_callee_stack_depth(struct bpf_verifier_env *env, } #endif -int check_ctx_reg(struct bpf_verifier_env *env, - const struct bpf_reg_state *reg, int regno) +static int __check_buffer_access(struct bpf_verifier_env *env, + const char *buf_info, + const struct bpf_reg_state *reg, + int regno, int off, int size) { - /* Access to ctx or passing it to a helper is only allowed in - * its original, unmodified form. - */ - - if (reg->off) { - verbose(env, "dereference of modified ctx ptr R%d off=%d disallowed\n", - regno, reg->off); + if (off < 0) { + verbose(env, + "R%d invalid %s buffer access: off=%d, size=%d\n", + regno, buf_info, off, size); return -EACCES; } - if (!tnum_is_const(reg->var_off) || reg->var_off.value) { char tn_buf[48]; tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); - verbose(env, "variable ctx access var_off=%s disallowed\n", tn_buf); + verbose(env, + "R%d invalid variable buffer offset: off=%d, var_off=%s\n", + regno, off, tn_buf); return -EACCES; } @@ -2763,27 +4379,43 @@ static int check_tp_buffer_access(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, int regno, int off, int size) { - if (off < 0) { - verbose(env, - "R%d invalid tracepoint buffer access: off=%d, size=%d", - regno, off, size); - return -EACCES; - } - if (!tnum_is_const(reg->var_off) || reg->var_off.value) { - char tn_buf[48]; + int err; + + err = __check_buffer_access(env, "tracepoint", reg, regno, off, size); + if (err) + return err; - tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); - verbose(env, - "R%d invalid variable buffer offset: off=%d, var_off=%s", - regno, off, tn_buf); - return -EACCES; - } if (off + size > env->prog->aux->max_tp_access) env->prog->aux->max_tp_access = off + size; return 0; } +static int check_buffer_access(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, + int regno, int off, int size, + bool zero_size_allowed, + u32 *max_access) +{ + const char *buf_info = type_is_rdonly_mem(reg->type) ? "rdonly" : "rdwr"; + int err; + + err = __check_buffer_access(env, buf_info, reg, regno, off, size); + if (err) + return err; + + if (off + size > *max_access) + *max_access = off + size; + + return 0; +} + +/* BPF architecture zero extends alu32 ops into 64-bit registesr */ +static void zext_32_to_64(struct bpf_reg_state *reg) +{ + reg->var_off = tnum_subreg(reg->var_off); + __reg_assign_32_into_64(reg); +} /* truncate register to smaller size (in bytes) * must be called with size < BPF_REG_SIZE @@ -2806,11 +4438,34 @@ static void coerce_reg_to_size(struct bpf_reg_state *reg, int size) } reg->smin_value = reg->umin_value; reg->smax_value = reg->umax_value; + + /* If size is smaller than 32bit register the 32bit register + * values are also truncated so we push 64-bit bounds into + * 32-bit bounds. Above were truncated < 32-bits already. + */ + if (size >= 4) + return; + __reg_combine_64_into_32(reg); } static bool bpf_map_is_rdonly(const struct bpf_map *map) { - return (map->map_flags & BPF_F_RDONLY_PROG) && map->frozen; + /* A map is considered read-only if the following condition are true: + * + * 1) BPF program side cannot change any of the map content. The + * BPF_F_RDONLY_PROG flag is throughout the lifetime of a map + * and was set at map creation time. + * 2) The map value(s) have been initialized from user space by a + * loader and then "frozen", such that no new map update/delete + * operations from syscall side are possible for the rest of + * the map's lifetime from that point onwards. + * 3) Any parallel/pending map update/delete operations from syscall + * side have been completed. Only after that point, it's safe to + * assume that map value(s) are immutable. + */ + return (map->map_flags & BPF_F_RDONLY_PROG) && + READ_ONCE(map->frozen) && + !bpf_map_write_active(map); } static int bpf_map_direct_read(struct bpf_map *map, int off, int size, u64 *val) @@ -2850,8 +4505,9 @@ static int check_ptr_to_btf_access(struct bpf_verifier_env *env, int value_regno) { struct bpf_reg_state *reg = regs + regno; - const struct btf_type *t = btf_type_by_id(btf_vmlinux, reg->btf_id); - const char *tname = btf_name_by_offset(btf_vmlinux, t->name_off); + const struct btf_type *t = btf_type_by_id(reg->btf, reg->btf_id); + const char *tname = btf_name_by_offset(reg->btf, t->name_off); + enum bpf_type_flag flag = 0; u32 btf_id; int ret; @@ -2871,35 +4527,190 @@ static int check_ptr_to_btf_access(struct bpf_verifier_env *env, return -EACCES; } + if (reg->type & MEM_USER) { + verbose(env, + "R%d is ptr_%s access user memory: off=%d\n", + regno, tname, off); + return -EACCES; + } + + if (reg->type & MEM_PERCPU) { + verbose(env, + "R%d is ptr_%s access percpu memory: off=%d\n", + regno, tname, off); + return -EACCES; + } + if (env->ops->btf_struct_access) { - ret = env->ops->btf_struct_access(&env->log, t, off, size, - atype, &btf_id); + ret = env->ops->btf_struct_access(&env->log, reg->btf, t, + off, size, atype, &btf_id, &flag); } else { if (atype != BPF_READ) { verbose(env, "only read is supported\n"); return -EACCES; } - ret = btf_struct_access(&env->log, t, off, size, atype, - &btf_id); + ret = btf_struct_access(&env->log, reg->btf, t, off, size, + atype, &btf_id, &flag); } if (ret < 0) return ret; - if (atype == BPF_READ) { - if (ret == SCALAR_VALUE) { - mark_reg_unknown(env, regs, value_regno); - return 0; - } - mark_reg_known_zero(env, regs, value_regno); - regs[value_regno].type = PTR_TO_BTF_ID; - regs[value_regno].btf_id = btf_id; + /* If this is an untrusted pointer, all pointers formed by walking it + * also inherit the untrusted flag. + */ + if (type_flag(reg->type) & PTR_UNTRUSTED) + flag |= PTR_UNTRUSTED; + + if (atype == BPF_READ && value_regno >= 0) + mark_btf_ld_reg(env, regs, value_regno, ret, reg->btf, btf_id, flag); + + return 0; +} + +static int check_ptr_to_map_access(struct bpf_verifier_env *env, + struct bpf_reg_state *regs, + int regno, int off, int size, + enum bpf_access_type atype, + int value_regno) +{ + struct bpf_reg_state *reg = regs + regno; + struct bpf_map *map = reg->map_ptr; + enum bpf_type_flag flag = 0; + const struct btf_type *t; + const char *tname; + u32 btf_id; + int ret; + + if (!btf_vmlinux) { + verbose(env, "map_ptr access not supported without CONFIG_DEBUG_INFO_BTF\n"); + return -ENOTSUPP; + } + + if (!map->ops->map_btf_id || !*map->ops->map_btf_id) { + verbose(env, "map_ptr access not supported for map type %d\n", + map->map_type); + return -ENOTSUPP; } + t = btf_type_by_id(btf_vmlinux, *map->ops->map_btf_id); + tname = btf_name_by_offset(btf_vmlinux, t->name_off); + + if (!env->allow_ptr_to_map_access) { + verbose(env, + "%s access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n", + tname); + return -EPERM; + } + + if (off < 0) { + verbose(env, "R%d is %s invalid negative access: off=%d\n", + regno, tname, off); + return -EACCES; + } + + if (atype != BPF_READ) { + verbose(env, "only read from %s is supported\n", tname); + return -EACCES; + } + + ret = btf_struct_access(&env->log, btf_vmlinux, t, off, size, atype, &btf_id, &flag); + if (ret < 0) + return ret; + + if (value_regno >= 0) + mark_btf_ld_reg(env, regs, value_regno, ret, btf_vmlinux, btf_id, flag); + + return 0; +} + +/* Check that the stack access at the given offset is within bounds. The + * maximum valid offset is -1. + * + * The minimum valid offset is -MAX_BPF_STACK for writes, and + * -state->allocated_stack for reads. + */ +static int check_stack_slot_within_bounds(int off, + struct bpf_func_state *state, + enum bpf_access_type t) +{ + int min_valid_off; + + if (t == BPF_WRITE) + min_valid_off = -MAX_BPF_STACK; + else + min_valid_off = -state->allocated_stack; + + if (off < min_valid_off || off > -1) + return -EACCES; return 0; } +/* Check that the stack access at 'regno + off' falls within the maximum stack + * bounds. + * + * 'off' includes `regno->offset`, but not its dynamic part (if any). + */ +static int check_stack_access_within_bounds( + struct bpf_verifier_env *env, + int regno, int off, int access_size, + enum bpf_access_src src, enum bpf_access_type type) +{ + struct bpf_reg_state *regs = cur_regs(env); + struct bpf_reg_state *reg = regs + regno; + struct bpf_func_state *state = func(env, reg); + int min_off, max_off; + int err; + char *err_extra; + + if (src == ACCESS_HELPER) + /* We don't know if helpers are reading or writing (or both). */ + err_extra = " indirect access to"; + else if (type == BPF_READ) + err_extra = " read from"; + else + err_extra = " write to"; + + if (tnum_is_const(reg->var_off)) { + min_off = reg->var_off.value + off; + if (access_size > 0) + max_off = min_off + access_size - 1; + else + max_off = min_off; + } else { + if (reg->smax_value >= BPF_MAX_VAR_OFF || + reg->smin_value <= -BPF_MAX_VAR_OFF) { + verbose(env, "invalid unbounded variable-offset%s stack R%d\n", + err_extra, regno); + return -EACCES; + } + min_off = reg->smin_value + off; + if (access_size > 0) + max_off = reg->smax_value + off + access_size - 1; + else + max_off = min_off; + } + + err = check_stack_slot_within_bounds(min_off, state, type); + if (!err) + err = check_stack_slot_within_bounds(max_off, state, type); + + if (err) { + if (tnum_is_const(reg->var_off)) { + verbose(env, "invalid%s stack R%d off=%d size=%d\n", + err_extra, regno, off, access_size); + } else { + char tn_buf[48]; + + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose(env, "invalid variable-offset%s stack R%d var_off=%s size=%d\n", + err_extra, regno, tn_buf, access_size); + } + } + return err; +} + /* check whether memory at (regno + off) is accessible for t = (read | write) * if t==write, value_regno is a register which value is stored into memory * if t==read, value_regno is a register which will receive the value from memory @@ -2927,7 +4738,21 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn /* for access checks, reg->off is just part of off */ off += reg->off; - if (reg->type == PTR_TO_MAP_VALUE) { + if (reg->type == PTR_TO_MAP_KEY) { + if (t == BPF_WRITE) { + verbose(env, "write to change key R%d not allowed\n", regno); + return -EACCES; + } + + err = check_mem_region_access(env, regno, off, size, + reg->map_ptr->key_size, false); + if (err) + return err; + if (value_regno >= 0) + mark_reg_unknown(env, regs, value_regno); + } else if (reg->type == PTR_TO_MAP_VALUE) { + struct bpf_map_value_off_desc *kptr_off_desc = NULL; + if (t == BPF_WRITE && value_regno >= 0 && is_pointer_value(env, value_regno)) { verbose(env, "R%d leaks addr into map\n", value_regno); @@ -2936,8 +4761,16 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn err = check_map_access_type(env, regno, off, size, t); if (err) return err; - err = check_map_access(env, regno, off, size, false); - if (!err && t == BPF_READ && value_regno >= 0) { + err = check_map_access(env, regno, off, size, false, ACCESS_DIRECT); + if (err) + return err; + if (tnum_is_const(reg->var_off)) + kptr_off_desc = bpf_map_kptr_off_contains(reg->map_ptr, + off + reg->var_off.value); + if (kptr_off_desc) { + err = check_map_kptr_access(env, regno, value_regno, insn_idx, + kptr_off_desc); + } else if (t == BPF_READ && value_regno >= 0) { struct bpf_map *map = reg->map_ptr; /* if map is read-only, track its contents as scalars */ @@ -2958,8 +4791,34 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn mark_reg_unknown(env, regs, value_regno); } } + } else if (base_type(reg->type) == PTR_TO_MEM) { + bool rdonly_mem = type_is_rdonly_mem(reg->type); + + if (type_may_be_null(reg->type)) { + verbose(env, "R%d invalid mem access '%s'\n", regno, + reg_type_str(env, reg->type)); + return -EACCES; + } + + if (t == BPF_WRITE && rdonly_mem) { + verbose(env, "R%d cannot write into %s\n", + regno, reg_type_str(env, reg->type)); + return -EACCES; + } + + if (t == BPF_WRITE && value_regno >= 0 && + is_pointer_value(env, value_regno)) { + verbose(env, "R%d leaks addr into mem\n", value_regno); + return -EACCES; + } + + err = check_mem_region_access(env, regno, off, size, + reg->mem_size, false); + if (!err && value_regno >= 0 && (t == BPF_READ || rdonly_mem)) + mark_reg_unknown(env, regs, value_regno); } else if (reg->type == PTR_TO_CTX) { enum bpf_reg_type reg_type = SCALAR_VALUE; + struct btf *btf = NULL; u32 btf_id = 0; if (t == BPF_WRITE && value_regno >= 0 && @@ -2968,11 +4827,12 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn return -EACCES; } - err = check_ctx_reg(env, reg, regno); + err = check_ptr_off_reg(env, reg, regno); if (err < 0) return err; - err = check_ctx_access(env, insn_idx, off, size, t, ®_type, &btf_id); + err = check_ctx_access(env, insn_idx, off, size, t, ®_type, &btf, + &btf_id); if (err) verbose_linfo(env, insn_idx, "; "); if (!err && t == BPF_READ && value_regno >= 0) { @@ -2985,7 +4845,7 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn } else { mark_reg_known_zero(env, regs, value_regno); - if (reg_type_may_be_null(reg_type)) + if (type_may_be_null(reg_type)) regs[value_regno].id = ++env->id_gen; /* A load of ctx field could have different * actual load size with the one encoded in the @@ -2993,15 +4853,17 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn * a sub-register. */ regs[value_regno].subreg_def = DEF_NOT_SUBREG; - if (reg_type == PTR_TO_BTF_ID) + if (base_type(reg_type) == PTR_TO_BTF_ID) { + regs[value_regno].btf = btf; regs[value_regno].btf_id = btf_id; + } } regs[value_regno].type = reg_type; } } else if (reg->type == PTR_TO_STACK) { - off += reg->var_off.value; - err = check_stack_access(env, reg, off, size); + /* Basic bounds checks. */ + err = check_stack_access_within_bounds(env, regno, off, size, ACCESS_DIRECT, t); if (err) return err; @@ -3010,12 +4872,12 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn if (err) return err; - if (t == BPF_WRITE) - err = check_stack_write(env, state, off, size, - value_regno, insn_idx); - else - err = check_stack_read(env, state, off, size, + if (t == BPF_READ) + err = check_stack_read(env, regno, off, size, value_regno); + else + err = check_stack_write(env, regno, off, size, + value_regno, insn_idx); } else if (reg_is_pkt_pointer(reg)) { if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) { verbose(env, "cannot write into packet\n"); @@ -3044,7 +4906,7 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn } else if (type_is_sk_pointer(reg->type)) { if (t == BPF_WRITE) { verbose(env, "R%d cannot write into %s\n", - regno, reg_type_str[reg->type]); + regno, reg_type_str(env, reg->type)); return -EACCES; } err = check_sock_access(env, insn_idx, regno, off, size, t); @@ -3054,12 +4916,36 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn err = check_tp_buffer_access(env, reg, regno, off, size); if (!err && t == BPF_READ && value_regno >= 0) mark_reg_unknown(env, regs, value_regno); - } else if (reg->type == PTR_TO_BTF_ID) { + } else if (base_type(reg->type) == PTR_TO_BTF_ID && + !type_may_be_null(reg->type)) { err = check_ptr_to_btf_access(env, regs, regno, off, size, t, value_regno); + } else if (reg->type == CONST_PTR_TO_MAP) { + err = check_ptr_to_map_access(env, regs, regno, off, size, t, + value_regno); + } else if (base_type(reg->type) == PTR_TO_BUF) { + bool rdonly_mem = type_is_rdonly_mem(reg->type); + u32 *max_access; + + if (rdonly_mem) { + if (t == BPF_WRITE) { + verbose(env, "R%d cannot write into %s\n", + regno, reg_type_str(env, reg->type)); + return -EACCES; + } + max_access = &env->prog->aux->max_rdonly_access; + } else { + max_access = &env->prog->aux->max_rdwr_access; + } + + err = check_buffer_access(env, reg, regno, off, size, false, + max_access); + + if (!err && value_regno >= 0 && (rdonly_mem || t == BPF_READ)) + mark_reg_unknown(env, regs, value_regno); } else { verbose(env, "R%d invalid mem access '%s'\n", regno, - reg_type_str[reg->type]); + reg_type_str(env, reg->type)); return -EACCES; } @@ -3071,13 +4957,30 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn return err; } -static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn) +static int check_atomic(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn) { + int load_reg; int err; - if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) || - insn->imm != 0) { - verbose(env, "BPF_XADD uses reserved fields\n"); + switch (insn->imm) { + case BPF_ADD: + case BPF_ADD | BPF_FETCH: + case BPF_AND: + case BPF_AND | BPF_FETCH: + case BPF_OR: + case BPF_OR | BPF_FETCH: + case BPF_XOR: + case BPF_XOR | BPF_FETCH: + case BPF_XCHG: + case BPF_CMPXCHG: + break; + default: + verbose(env, "BPF_ATOMIC uses invalid atomic opcode %02x\n", insn->imm); + return -EINVAL; + } + + if (BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) { + verbose(env, "invalid atomic operand size\n"); return -EINVAL; } @@ -3091,6 +4994,20 @@ static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_ins if (err) return err; + if (insn->imm == BPF_CMPXCHG) { + /* Check comparison of R0 with memory location */ + const u32 aux_reg = BPF_REG_0; + + err = check_reg_arg(env, aux_reg, SRC_OP); + if (err) + return err; + + if (is_pointer_value(env, aux_reg)) { + verbose(env, "R%d leaks addr into mem\n", aux_reg); + return -EACCES; + } + } + if (is_pointer_value(env, insn->src_reg)) { verbose(env, "R%d leaks addr into mem\n", insn->src_reg); return -EACCES; @@ -3100,90 +5017,109 @@ static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_ins is_pkt_reg(env, insn->dst_reg) || is_flow_key_reg(env, insn->dst_reg) || is_sk_reg(env, insn->dst_reg)) { - verbose(env, "BPF_XADD stores into R%d %s is not allowed\n", + verbose(env, "BPF_ATOMIC stores into R%d %s is not allowed\n", insn->dst_reg, - reg_type_str[reg_state(env, insn->dst_reg)->type]); + reg_type_str(env, reg_state(env, insn->dst_reg)->type)); return -EACCES; } - /* check whether atomic_add can read the memory */ + if (insn->imm & BPF_FETCH) { + if (insn->imm == BPF_CMPXCHG) + load_reg = BPF_REG_0; + else + load_reg = insn->src_reg; + + /* check and record load of old value */ + err = check_reg_arg(env, load_reg, DST_OP); + if (err) + return err; + } else { + /* This instruction accesses a memory location but doesn't + * actually load it into a register. + */ + load_reg = -1; + } + + /* Check whether we can read the memory, with second call for fetch + * case to simulate the register fill. + */ err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, BPF_SIZE(insn->code), BPF_READ, -1, true); + if (!err && load_reg >= 0) + err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, + BPF_SIZE(insn->code), BPF_READ, load_reg, + true); if (err) return err; - /* check whether atomic_add can write into the same memory */ - return check_mem_access(env, insn_idx, insn->dst_reg, insn->off, - BPF_SIZE(insn->code), BPF_WRITE, -1, true); -} - -static int __check_stack_boundary(struct bpf_verifier_env *env, u32 regno, - int off, int access_size, - bool zero_size_allowed) -{ - struct bpf_reg_state *reg = reg_state(env, regno); - - if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 || - access_size < 0 || (access_size == 0 && !zero_size_allowed)) { - if (tnum_is_const(reg->var_off)) { - verbose(env, "invalid stack type R%d off=%d access_size=%d\n", - regno, off, access_size); - } else { - char tn_buf[48]; + /* Check whether we can write into the same memory. */ + err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, + BPF_SIZE(insn->code), BPF_WRITE, -1, true); + if (err) + return err; - tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); - verbose(env, "invalid stack type R%d var_off=%s access_size=%d\n", - regno, tn_buf, access_size); - } - return -EACCES; - } return 0; } -/* when register 'regno' is passed into function that will read 'access_size' - * bytes from that pointer, make sure that it's within stack boundary - * and all elements of stack are initialized. - * Unlike most pointer bounds-checking functions, this one doesn't take an - * 'off' argument, so it has to add in reg->off itself. +/* When register 'regno' is used to read the stack (either directly or through + * a helper function) make sure that it's within stack boundary and, depending + * on the access type, that all elements of the stack are initialized. + * + * 'off' includes 'regno->off', but not its dynamic part (if any). + * + * All registers that have been spilled on the stack in the slots within the + * read offsets are marked as read. */ -static int check_stack_boundary(struct bpf_verifier_env *env, int regno, - int access_size, bool zero_size_allowed, - struct bpf_call_arg_meta *meta) +static int check_stack_range_initialized( + struct bpf_verifier_env *env, int regno, int off, + int access_size, bool zero_size_allowed, + enum bpf_access_src type, struct bpf_call_arg_meta *meta) { struct bpf_reg_state *reg = reg_state(env, regno); struct bpf_func_state *state = func(env, reg); int err, min_off, max_off, i, j, slot, spi; + char *err_extra = type == ACCESS_HELPER ? " indirect" : ""; + enum bpf_access_type bounds_check_type; + /* Some accesses can write anything into the stack, others are + * read-only. + */ + bool clobber = false; - if (reg->type != PTR_TO_STACK) { - /* Allow zero-byte read from NULL, regardless of pointer type */ - if (zero_size_allowed && access_size == 0 && - register_is_null(reg)) - return 0; - - verbose(env, "R%d type=%s expected=%s\n", regno, - reg_type_str[reg->type], - reg_type_str[PTR_TO_STACK]); + if (access_size == 0 && !zero_size_allowed) { + verbose(env, "invalid zero-sized read\n"); return -EACCES; } + if (type == ACCESS_HELPER) { + /* The bounds checks for writes are more permissive than for + * reads. However, if raw_mode is not set, we'll do extra + * checks below. + */ + bounds_check_type = BPF_WRITE; + clobber = true; + } else { + bounds_check_type = BPF_READ; + } + err = check_stack_access_within_bounds(env, regno, off, access_size, + type, bounds_check_type); + if (err) + return err; + + if (tnum_is_const(reg->var_off)) { - min_off = max_off = reg->var_off.value + reg->off; - err = __check_stack_boundary(env, regno, min_off, access_size, - zero_size_allowed); - if (err) - return err; + min_off = max_off = reg->var_off.value + off; } else { /* Variable offset is prohibited for unprivileged mode for * simplicity since it requires corresponding support in * Spectre masking for stack ALU. * See also retrieve_ptr_limit(). */ - if (!env->allow_ptr_leaks) { + if (!env->bypass_spec_v1) { char tn_buf[48]; tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); - verbose(env, "R%d indirect variable offset stack access prohibited for !root, var_off=%s\n", - regno, tn_buf); + verbose(env, "R%d%s variable offset stack access prohibited for !root, var_off=%s\n", + regno, err_extra, tn_buf); return -EACCES; } /* Only initialized buffer on stack is allowed to be accessed @@ -3195,28 +5131,8 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno, if (meta && meta->raw_mode) meta = NULL; - if (reg->smax_value >= BPF_MAX_VAR_OFF || - reg->smax_value <= -BPF_MAX_VAR_OFF) { - verbose(env, "R%d unbounded indirect variable offset stack access\n", - regno); - return -EACCES; - } - min_off = reg->smin_value + reg->off; - max_off = reg->smax_value + reg->off; - err = __check_stack_boundary(env, regno, min_off, access_size, - zero_size_allowed); - if (err) { - verbose(env, "R%d min value is outside of stack bound\n", - regno); - return err; - } - err = __check_stack_boundary(env, regno, max_off, access_size, - zero_size_allowed); - if (err) { - verbose(env, "R%d max value is outside of stack bound\n", - regno); - return err; - } + min_off = reg->smin_value + off; + max_off = reg->smax_value + off; } if (meta && meta->raw_mode) { @@ -3236,28 +5152,38 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno, if (*stype == STACK_MISC) goto mark; if (*stype == STACK_ZERO) { - /* helper can write anything into the stack */ - *stype = STACK_MISC; + if (clobber) { + /* helper can write anything into the stack */ + *stype = STACK_MISC; + } goto mark; } - if (state->stack[spi].slot_type[0] == STACK_SPILL && - state->stack[spi].spilled_ptr.type == SCALAR_VALUE) { - __mark_reg_unknown(env, &state->stack[spi].spilled_ptr); - for (j = 0; j < BPF_REG_SIZE; j++) - state->stack[spi].slot_type[j] = STACK_MISC; + + if (is_spilled_reg(&state->stack[spi]) && + base_type(state->stack[spi].spilled_ptr.type) == PTR_TO_BTF_ID) + goto mark; + + if (is_spilled_reg(&state->stack[spi]) && + (state->stack[spi].spilled_ptr.type == SCALAR_VALUE || + env->allow_ptr_leaks)) { + if (clobber) { + __mark_reg_unknown(env, &state->stack[spi].spilled_ptr); + for (j = 0; j < BPF_REG_SIZE; j++) + scrub_spilled_slot(&state->stack[spi].slot_type[j]); + } goto mark; } err: if (tnum_is_const(reg->var_off)) { - verbose(env, "invalid indirect read from stack off %d+%d size %d\n", - min_off, i - min_off, access_size); + verbose(env, "invalid%s read from stack R%d off %d+%d size %d\n", + err_extra, regno, min_off, i - min_off, access_size); } else { char tn_buf[48]; tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); - verbose(env, "invalid indirect read from stack var_off %s+%d size %d\n", - tn_buf, i - min_off, access_size); + verbose(env, "invalid%s read from stack R%d var_off %s+%d size %d\n", + err_extra, regno, tn_buf, i - min_off, access_size); } return -EACCES; mark: @@ -3276,23 +5202,204 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno, struct bpf_call_arg_meta *meta) { struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; + u32 *max_access; - switch (reg->type) { + switch (base_type(reg->type)) { case PTR_TO_PACKET: case PTR_TO_PACKET_META: return check_packet_access(env, regno, reg->off, access_size, zero_size_allowed); + case PTR_TO_MAP_KEY: + if (meta && meta->raw_mode) { + verbose(env, "R%d cannot write into %s\n", regno, + reg_type_str(env, reg->type)); + return -EACCES; + } + return check_mem_region_access(env, regno, reg->off, access_size, + reg->map_ptr->key_size, false); case PTR_TO_MAP_VALUE: if (check_map_access_type(env, regno, reg->off, access_size, meta && meta->raw_mode ? BPF_WRITE : BPF_READ)) return -EACCES; return check_map_access(env, regno, reg->off, access_size, - zero_size_allowed); - default: /* scalar_value|ptr_to_stack or invalid ptr */ - return check_stack_boundary(env, regno, access_size, - zero_size_allowed, meta); + zero_size_allowed, ACCESS_HELPER); + case PTR_TO_MEM: + if (type_is_rdonly_mem(reg->type)) { + if (meta && meta->raw_mode) { + verbose(env, "R%d cannot write into %s\n", regno, + reg_type_str(env, reg->type)); + return -EACCES; + } + } + return check_mem_region_access(env, regno, reg->off, + access_size, reg->mem_size, + zero_size_allowed); + case PTR_TO_BUF: + if (type_is_rdonly_mem(reg->type)) { + if (meta && meta->raw_mode) { + verbose(env, "R%d cannot write into %s\n", regno, + reg_type_str(env, reg->type)); + return -EACCES; + } + + max_access = &env->prog->aux->max_rdonly_access; + } else { + max_access = &env->prog->aux->max_rdwr_access; + } + return check_buffer_access(env, reg, regno, reg->off, + access_size, zero_size_allowed, + max_access); + case PTR_TO_STACK: + return check_stack_range_initialized( + env, + regno, reg->off, access_size, + zero_size_allowed, ACCESS_HELPER, meta); + case PTR_TO_CTX: + /* in case the function doesn't know how to access the context, + * (because we are in a program of type SYSCALL for example), we + * can not statically check its size. + * Dynamically check it now. + */ + if (!env->ops->convert_ctx_access) { + enum bpf_access_type atype = meta && meta->raw_mode ? BPF_WRITE : BPF_READ; + int offset = access_size - 1; + + /* Allow zero-byte read from PTR_TO_CTX */ + if (access_size == 0) + return zero_size_allowed ? 0 : -EACCES; + + return check_mem_access(env, env->insn_idx, regno, offset, BPF_B, + atype, -1, false); + } + + fallthrough; + default: /* scalar_value or invalid ptr */ + /* Allow zero-byte read from NULL, regardless of pointer type */ + if (zero_size_allowed && access_size == 0 && + register_is_null(reg)) + return 0; + + verbose(env, "R%d type=%s ", regno, + reg_type_str(env, reg->type)); + verbose(env, "expected=%s\n", reg_type_str(env, PTR_TO_STACK)); + return -EACCES; + } +} + +static int check_mem_size_reg(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, u32 regno, + bool zero_size_allowed, + struct bpf_call_arg_meta *meta) +{ + int err; + + /* This is used to refine r0 return value bounds for helpers + * that enforce this value as an upper bound on return values. + * See do_refine_retval_range() for helpers that can refine + * the return value. C type of helper is u32 so we pull register + * bound from umax_value however, if negative verifier errors + * out. Only upper bounds can be learned because retval is an + * int type and negative retvals are allowed. + */ + meta->msize_max_value = reg->umax_value; + + /* The register is SCALAR_VALUE; the access check + * happens using its boundaries. + */ + if (!tnum_is_const(reg->var_off)) + /* For unprivileged variable accesses, disable raw + * mode so that the program is required to + * initialize all the memory that the helper could + * just partially fill up. + */ + meta = NULL; + + if (reg->smin_value < 0) { + verbose(env, "R%d min value is negative, either use unsigned or 'var &= const'\n", + regno); + return -EACCES; + } + + if (reg->umin_value == 0) { + err = check_helper_mem_access(env, regno - 1, 0, + zero_size_allowed, + meta); + if (err) + return err; + } + + if (reg->umax_value >= BPF_MAX_VAR_SIZ) { + verbose(env, "R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n", + regno); + return -EACCES; + } + err = check_helper_mem_access(env, regno - 1, + reg->umax_value, + zero_size_allowed, meta); + if (!err) + err = mark_chain_precision(env, regno); + return err; +} + +int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg, + u32 regno, u32 mem_size) +{ + bool may_be_null = type_may_be_null(reg->type); + struct bpf_reg_state saved_reg; + struct bpf_call_arg_meta meta; + int err; + + if (register_is_null(reg)) + return 0; + + memset(&meta, 0, sizeof(meta)); + /* Assuming that the register contains a value check if the memory + * access is safe. Temporarily save and restore the register's state as + * the conversion shouldn't be visible to a caller. + */ + if (may_be_null) { + saved_reg = *reg; + mark_ptr_not_null_reg(reg); + } + + err = check_helper_mem_access(env, regno, mem_size, true, &meta); + /* Check access for BPF_WRITE */ + meta.raw_mode = true; + err = err ?: check_helper_mem_access(env, regno, mem_size, true, &meta); + + if (may_be_null) + *reg = saved_reg; + + return err; +} + +int check_kfunc_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg, + u32 regno) +{ + struct bpf_reg_state *mem_reg = &cur_regs(env)[regno - 1]; + bool may_be_null = type_may_be_null(mem_reg->type); + struct bpf_reg_state saved_reg; + struct bpf_call_arg_meta meta; + int err; + + WARN_ON_ONCE(regno < BPF_REG_2 || regno > BPF_REG_5); + + memset(&meta, 0, sizeof(meta)); + + if (may_be_null) { + saved_reg = *mem_reg; + mark_ptr_not_null_reg(mem_reg); } + + err = check_mem_size_reg(env, reg, regno, true, &meta); + /* Check access for BPF_WRITE */ + meta.raw_mode = true; + err = err ?: check_mem_size_reg(env, reg, regno, true, &meta); + + if (may_be_null) + *mem_reg = saved_reg; + return err; } /* Implementation details: @@ -3323,10 +5430,6 @@ static int process_spin_lock(struct bpf_verifier_env *env, int regno, struct bpf_map *map = reg->map_ptr; u64 val = reg->var_off.value; - if (reg->type != PTR_TO_MAP_VALUE) { - verbose(env, "R%d is not a pointer to map_value\n", regno); - return -EINVAL; - } if (!is_const) { verbose(env, "R%d doesn't have constant offset. bpf_spin_lock has to be at the constant offset\n", @@ -3380,11 +5483,99 @@ static int process_spin_lock(struct bpf_verifier_env *env, int regno, return 0; } -static bool arg_type_is_mem_ptr(enum bpf_arg_type type) +static int process_timer_func(struct bpf_verifier_env *env, int regno, + struct bpf_call_arg_meta *meta) +{ + struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; + bool is_const = tnum_is_const(reg->var_off); + struct bpf_map *map = reg->map_ptr; + u64 val = reg->var_off.value; + + if (!is_const) { + verbose(env, + "R%d doesn't have constant offset. bpf_timer has to be at the constant offset\n", + regno); + return -EINVAL; + } + if (!map->btf) { + verbose(env, "map '%s' has to have BTF in order to use bpf_timer\n", + map->name); + return -EINVAL; + } + if (!map_value_has_timer(map)) { + if (map->timer_off == -E2BIG) + verbose(env, + "map '%s' has more than one 'struct bpf_timer'\n", + map->name); + else if (map->timer_off == -ENOENT) + verbose(env, + "map '%s' doesn't have 'struct bpf_timer'\n", + map->name); + else + verbose(env, + "map '%s' is not a struct type or bpf_timer is mangled\n", + map->name); + return -EINVAL; + } + if (map->timer_off != val + reg->off) { + verbose(env, "off %lld doesn't point to 'struct bpf_timer' that is at %d\n", + val + reg->off, map->timer_off); + return -EINVAL; + } + if (meta->map_ptr) { + verbose(env, "verifier bug. Two map pointers in a timer helper\n"); + return -EFAULT; + } + meta->map_uid = reg->map_uid; + meta->map_ptr = map; + return 0; +} + +static int process_kptr_func(struct bpf_verifier_env *env, int regno, + struct bpf_call_arg_meta *meta) { - return type == ARG_PTR_TO_MEM || - type == ARG_PTR_TO_MEM_OR_NULL || - type == ARG_PTR_TO_UNINIT_MEM; + struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; + struct bpf_map_value_off_desc *off_desc; + struct bpf_map *map_ptr = reg->map_ptr; + u32 kptr_off; + int ret; + + if (!tnum_is_const(reg->var_off)) { + verbose(env, + "R%d doesn't have constant offset. kptr has to be at the constant offset\n", + regno); + return -EINVAL; + } + if (!map_ptr->btf) { + verbose(env, "map '%s' has to have BTF in order to use bpf_kptr_xchg\n", + map_ptr->name); + return -EINVAL; + } + if (!map_value_has_kptrs(map_ptr)) { + ret = PTR_ERR_OR_ZERO(map_ptr->kptr_off_tab); + if (ret == -E2BIG) + verbose(env, "map '%s' has more than %d kptr\n", map_ptr->name, + BPF_MAP_VALUE_OFF_MAX); + else if (ret == -EEXIST) + verbose(env, "map '%s' has repeating kptr BTF tags\n", map_ptr->name); + else + verbose(env, "map '%s' has no valid kptr\n", map_ptr->name); + return -EINVAL; + } + + meta->map_ptr = map_ptr; + kptr_off = reg->off + reg->var_off.value; + off_desc = bpf_map_kptr_off_contains(map_ptr, kptr_off); + if (!off_desc) { + verbose(env, "off=%d doesn't point to kptr\n", kptr_off); + return -EACCES; + } + if (off_desc->type != BPF_KPTR_REF) { + verbose(env, "off=%d kptr isn't referenced kptr\n", kptr_off); + return -EACCES; + } + meta->kptr_off_desc = off_desc; + return 0; } static bool arg_type_is_mem_size(enum bpf_arg_type type) @@ -3393,10 +5584,14 @@ static bool arg_type_is_mem_size(enum bpf_arg_type type) type == ARG_CONST_SIZE_OR_ZERO; } -static bool arg_type_is_int_ptr(enum bpf_arg_type type) +static bool arg_type_is_release(enum bpf_arg_type type) +{ + return type & OBJ_RELEASE; +} + +static bool arg_type_is_dynptr(enum bpf_arg_type type) { - return type == ARG_PTR_TO_INT || - type == ARG_PTR_TO_LONG; + return base_type(type) == ARG_PTR_TO_DYNPTR; } static int int_ptr_type_to_size(enum bpf_arg_type type) @@ -3409,12 +5604,305 @@ static int int_ptr_type_to_size(enum bpf_arg_type type) return -EINVAL; } -static int check_func_arg(struct bpf_verifier_env *env, u32 regno, +static int resolve_map_arg_type(struct bpf_verifier_env *env, + const struct bpf_call_arg_meta *meta, + enum bpf_arg_type *arg_type) +{ + if (!meta->map_ptr) { + /* kernel subsystem misconfigured verifier */ + verbose(env, "invalid map_ptr to access map->type\n"); + return -EACCES; + } + + switch (meta->map_ptr->map_type) { + case BPF_MAP_TYPE_SOCKMAP: + case BPF_MAP_TYPE_SOCKHASH: + if (*arg_type == ARG_PTR_TO_MAP_VALUE) { + *arg_type = ARG_PTR_TO_BTF_ID_SOCK_COMMON; + } else { + verbose(env, "invalid arg_type for sockmap/sockhash\n"); + return -EINVAL; + } + break; + case BPF_MAP_TYPE_BLOOM_FILTER: + if (meta->func_id == BPF_FUNC_map_peek_elem) + *arg_type = ARG_PTR_TO_MAP_VALUE; + break; + default: + break; + } + return 0; +} + +struct bpf_reg_types { + const enum bpf_reg_type types[10]; + u32 *btf_id; +}; + +static const struct bpf_reg_types map_key_value_types = { + .types = { + PTR_TO_STACK, + PTR_TO_PACKET, + PTR_TO_PACKET_META, + PTR_TO_MAP_KEY, + PTR_TO_MAP_VALUE, + }, +}; + +static const struct bpf_reg_types sock_types = { + .types = { + PTR_TO_SOCK_COMMON, + PTR_TO_SOCKET, + PTR_TO_TCP_SOCK, + PTR_TO_XDP_SOCK, + }, +}; + +#ifdef CONFIG_NET +static const struct bpf_reg_types btf_id_sock_common_types = { + .types = { + PTR_TO_SOCK_COMMON, + PTR_TO_SOCKET, + PTR_TO_TCP_SOCK, + PTR_TO_XDP_SOCK, + PTR_TO_BTF_ID, + }, + .btf_id = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON], +}; +#endif + +static const struct bpf_reg_types mem_types = { + .types = { + PTR_TO_STACK, + PTR_TO_PACKET, + PTR_TO_PACKET_META, + PTR_TO_MAP_KEY, + PTR_TO_MAP_VALUE, + PTR_TO_MEM, + PTR_TO_MEM | MEM_ALLOC, + PTR_TO_BUF, + }, +}; + +static const struct bpf_reg_types int_ptr_types = { + .types = { + PTR_TO_STACK, + PTR_TO_PACKET, + PTR_TO_PACKET_META, + PTR_TO_MAP_KEY, + PTR_TO_MAP_VALUE, + }, +}; + +static const struct bpf_reg_types fullsock_types = { .types = { PTR_TO_SOCKET } }; +static const struct bpf_reg_types scalar_types = { .types = { SCALAR_VALUE } }; +static const struct bpf_reg_types context_types = { .types = { PTR_TO_CTX } }; +static const struct bpf_reg_types alloc_mem_types = { .types = { PTR_TO_MEM | MEM_ALLOC } }; +static const struct bpf_reg_types const_map_ptr_types = { .types = { CONST_PTR_TO_MAP } }; +static const struct bpf_reg_types btf_ptr_types = { .types = { PTR_TO_BTF_ID } }; +static const struct bpf_reg_types spin_lock_types = { .types = { PTR_TO_MAP_VALUE } }; +static const struct bpf_reg_types percpu_btf_ptr_types = { .types = { PTR_TO_BTF_ID | MEM_PERCPU } }; +static const struct bpf_reg_types func_ptr_types = { .types = { PTR_TO_FUNC } }; +static const struct bpf_reg_types stack_ptr_types = { .types = { PTR_TO_STACK } }; +static const struct bpf_reg_types const_str_ptr_types = { .types = { PTR_TO_MAP_VALUE } }; +static const struct bpf_reg_types timer_types = { .types = { PTR_TO_MAP_VALUE } }; +static const struct bpf_reg_types kptr_types = { .types = { PTR_TO_MAP_VALUE } }; +static const struct bpf_reg_types dynptr_types = { + .types = { + PTR_TO_STACK, + PTR_TO_DYNPTR | DYNPTR_TYPE_LOCAL, + } +}; + +static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = { + [ARG_PTR_TO_MAP_KEY] = &map_key_value_types, + [ARG_PTR_TO_MAP_VALUE] = &map_key_value_types, + [ARG_CONST_SIZE] = &scalar_types, + [ARG_CONST_SIZE_OR_ZERO] = &scalar_types, + [ARG_CONST_ALLOC_SIZE_OR_ZERO] = &scalar_types, + [ARG_CONST_MAP_PTR] = &const_map_ptr_types, + [ARG_PTR_TO_CTX] = &context_types, + [ARG_PTR_TO_SOCK_COMMON] = &sock_types, +#ifdef CONFIG_NET + [ARG_PTR_TO_BTF_ID_SOCK_COMMON] = &btf_id_sock_common_types, +#endif + [ARG_PTR_TO_SOCKET] = &fullsock_types, + [ARG_PTR_TO_BTF_ID] = &btf_ptr_types, + [ARG_PTR_TO_SPIN_LOCK] = &spin_lock_types, + [ARG_PTR_TO_MEM] = &mem_types, + [ARG_PTR_TO_ALLOC_MEM] = &alloc_mem_types, + [ARG_PTR_TO_INT] = &int_ptr_types, + [ARG_PTR_TO_LONG] = &int_ptr_types, + [ARG_PTR_TO_PERCPU_BTF_ID] = &percpu_btf_ptr_types, + [ARG_PTR_TO_FUNC] = &func_ptr_types, + [ARG_PTR_TO_STACK] = &stack_ptr_types, + [ARG_PTR_TO_CONST_STR] = &const_str_ptr_types, + [ARG_PTR_TO_TIMER] = &timer_types, + [ARG_PTR_TO_KPTR] = &kptr_types, + [ARG_PTR_TO_DYNPTR] = &dynptr_types, +}; + +static int check_reg_type(struct bpf_verifier_env *env, u32 regno, enum bpf_arg_type arg_type, + const u32 *arg_btf_id, struct bpf_call_arg_meta *meta) { struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; - enum bpf_reg_type expected_type, type = reg->type; + enum bpf_reg_type expected, type = reg->type; + const struct bpf_reg_types *compatible; + int i, j; + + compatible = compatible_reg_types[base_type(arg_type)]; + if (!compatible) { + verbose(env, "verifier internal error: unsupported arg type %d\n", arg_type); + return -EFAULT; + } + + /* ARG_PTR_TO_MEM + RDONLY is compatible with PTR_TO_MEM and PTR_TO_MEM + RDONLY, + * but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM and NOT with PTR_TO_MEM + RDONLY + * + * Same for MAYBE_NULL: + * + * ARG_PTR_TO_MEM + MAYBE_NULL is compatible with PTR_TO_MEM and PTR_TO_MEM + MAYBE_NULL, + * but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM but NOT with PTR_TO_MEM + MAYBE_NULL + * + * Therefore we fold these flags depending on the arg_type before comparison. + */ + if (arg_type & MEM_RDONLY) + type &= ~MEM_RDONLY; + if (arg_type & PTR_MAYBE_NULL) + type &= ~PTR_MAYBE_NULL; + + for (i = 0; i < ARRAY_SIZE(compatible->types); i++) { + expected = compatible->types[i]; + if (expected == NOT_INIT) + break; + + if (type == expected) + goto found; + } + + verbose(env, "R%d type=%s expected=", regno, reg_type_str(env, reg->type)); + for (j = 0; j + 1 < i; j++) + verbose(env, "%s, ", reg_type_str(env, compatible->types[j])); + verbose(env, "%s\n", reg_type_str(env, compatible->types[j])); + return -EACCES; + +found: + if (reg->type == PTR_TO_BTF_ID) { + /* For bpf_sk_release, it needs to match against first member + * 'struct sock_common', hence make an exception for it. This + * allows bpf_sk_release to work for multiple socket types. + */ + bool strict_type_match = arg_type_is_release(arg_type) && + meta->func_id != BPF_FUNC_sk_release; + + if (!arg_btf_id) { + if (!compatible->btf_id) { + verbose(env, "verifier internal error: missing arg compatible BTF ID\n"); + return -EFAULT; + } + arg_btf_id = compatible->btf_id; + } + + if (meta->func_id == BPF_FUNC_kptr_xchg) { + if (map_kptr_match_type(env, meta->kptr_off_desc, reg, regno)) + return -EACCES; + } else { + if (arg_btf_id == BPF_PTR_POISON) { + verbose(env, "verifier internal error:"); + verbose(env, "R%d has non-overwritten BPF_PTR_POISON type\n", + regno); + return -EACCES; + } + + if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, reg->off, + btf_vmlinux, *arg_btf_id, + strict_type_match)) { + verbose(env, "R%d is of type %s but %s is expected\n", + regno, kernel_type_name(reg->btf, reg->btf_id), + kernel_type_name(btf_vmlinux, *arg_btf_id)); + return -EACCES; + } + } + } + + return 0; +} + +int check_func_arg_reg_off(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, int regno, + enum bpf_arg_type arg_type) +{ + enum bpf_reg_type type = reg->type; + bool fixed_off_ok = false; + + switch ((u32)type) { + /* Pointer types where reg offset is explicitly allowed: */ + case PTR_TO_STACK: + if (arg_type_is_dynptr(arg_type) && reg->off % BPF_REG_SIZE) { + verbose(env, "cannot pass in dynptr at an offset\n"); + return -EINVAL; + } + fallthrough; + case PTR_TO_PACKET: + case PTR_TO_PACKET_META: + case PTR_TO_MAP_KEY: + case PTR_TO_MAP_VALUE: + case PTR_TO_MEM: + case PTR_TO_MEM | MEM_RDONLY: + case PTR_TO_MEM | MEM_ALLOC: + case PTR_TO_BUF: + case PTR_TO_BUF | MEM_RDONLY: + case SCALAR_VALUE: + /* Some of the argument types nevertheless require a + * zero register offset. + */ + if (base_type(arg_type) != ARG_PTR_TO_ALLOC_MEM) + return 0; + break; + /* All the rest must be rejected, except PTR_TO_BTF_ID which allows + * fixed offset. + */ + case PTR_TO_BTF_ID: + /* When referenced PTR_TO_BTF_ID is passed to release function, + * it's fixed offset must be 0. In the other cases, fixed offset + * can be non-zero. + */ + if (arg_type_is_release(arg_type) && reg->off) { + verbose(env, "R%d must have zero offset when passed to release func\n", + regno); + return -EINVAL; + } + /* For arg is release pointer, fixed_off_ok must be false, but + * we already checked and rejected reg->off != 0 above, so set + * to true to allow fixed offset for all other cases. + */ + fixed_off_ok = true; + break; + default: + break; + } + return __check_ptr_off_reg(env, reg, regno, fixed_off_ok); +} + +static u32 stack_slot_get_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg) +{ + struct bpf_func_state *state = func(env, reg); + int spi = get_spi(reg->off); + + return state->stack[spi].spilled_ptr.id; +} + +static int check_func_arg(struct bpf_verifier_env *env, u32 arg, + struct bpf_call_arg_meta *meta, + const struct bpf_func_proto *fn) +{ + u32 regno = BPF_REG_1 + arg; + struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; + enum bpf_arg_type arg_type = fn->arg_type[arg]; + enum bpf_reg_type type = reg->type; + u32 *arg_btf_id = NULL; int err = 0; if (arg_type == ARG_DONTCARE) @@ -3439,108 +5927,91 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 regno, return -EACCES; } - if (arg_type == ARG_PTR_TO_MAP_KEY || - arg_type == ARG_PTR_TO_MAP_VALUE || - arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE || - arg_type == ARG_PTR_TO_MAP_VALUE_OR_NULL) { - expected_type = PTR_TO_STACK; - if (register_is_null(reg) && - arg_type == ARG_PTR_TO_MAP_VALUE_OR_NULL) - /* final test in check_stack_boundary() */; - else if (!type_is_pkt_pointer(type) && - type != PTR_TO_MAP_VALUE && - type != expected_type) - goto err_type; - } else if (arg_type == ARG_CONST_SIZE || - arg_type == ARG_CONST_SIZE_OR_ZERO) { - expected_type = SCALAR_VALUE; - if (type != expected_type) - goto err_type; - } else if (arg_type == ARG_CONST_MAP_PTR) { - expected_type = CONST_PTR_TO_MAP; - if (type != expected_type) - goto err_type; - } else if (arg_type == ARG_PTR_TO_CTX) { - expected_type = PTR_TO_CTX; - if (type != expected_type) - goto err_type; - err = check_ctx_reg(env, reg, regno); - if (err < 0) + if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE) { + err = resolve_map_arg_type(env, meta, &arg_type); + if (err) return err; - } else if (arg_type == ARG_PTR_TO_SOCK_COMMON) { - expected_type = PTR_TO_SOCK_COMMON; - /* Any sk pointer can be ARG_PTR_TO_SOCK_COMMON */ - if (!type_is_sk_pointer(type)) - goto err_type; - if (reg->ref_obj_id) { - if (meta->ref_obj_id) { - verbose(env, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n", - regno, reg->ref_obj_id, - meta->ref_obj_id); - return -EFAULT; - } - meta->ref_obj_id = reg->ref_obj_id; - } - } else if (arg_type == ARG_PTR_TO_SOCKET) { - expected_type = PTR_TO_SOCKET; - if (type != expected_type) - goto err_type; - } else if (arg_type == ARG_PTR_TO_BTF_ID) { - expected_type = PTR_TO_BTF_ID; - if (type != expected_type) - goto err_type; - if (reg->btf_id != meta->btf_id) { - verbose(env, "Helper has type %s got %s in R%d\n", - kernel_type_name(meta->btf_id), - kernel_type_name(reg->btf_id), regno); + } - return -EACCES; - } - if (!tnum_is_const(reg->var_off) || reg->var_off.value || reg->off) { - verbose(env, "R%d is a pointer to in-kernel struct with non-zero offset\n", + if (register_is_null(reg) && type_may_be_null(arg_type)) + /* A NULL register has a SCALAR_VALUE type, so skip + * type checking. + */ + goto skip_type_check; + + /* arg_btf_id and arg_size are in a union. */ + if (base_type(arg_type) == ARG_PTR_TO_BTF_ID) + arg_btf_id = fn->arg_btf_id[arg]; + + err = check_reg_type(env, regno, arg_type, arg_btf_id, meta); + if (err) + return err; + + err = check_func_arg_reg_off(env, reg, regno, arg_type); + if (err) + return err; + +skip_type_check: + if (arg_type_is_release(arg_type)) { + if (arg_type_is_dynptr(arg_type)) { + struct bpf_func_state *state = func(env, reg); + int spi = get_spi(reg->off); + + if (!is_spi_bounds_valid(state, spi, BPF_DYNPTR_NR_SLOTS) || + !state->stack[spi].spilled_ptr.id) { + verbose(env, "arg %d is an unacquired reference\n", regno); + return -EINVAL; + } + } else if (!reg->ref_obj_id && !register_is_null(reg)) { + verbose(env, "R%d must be referenced when passed to release function\n", regno); - return -EACCES; + return -EINVAL; } - } else if (arg_type == ARG_PTR_TO_SPIN_LOCK) { - if (meta->func_id == BPF_FUNC_spin_lock) { - if (process_spin_lock(env, regno, true)) - return -EACCES; - } else if (meta->func_id == BPF_FUNC_spin_unlock) { - if (process_spin_lock(env, regno, false)) - return -EACCES; - } else { - verbose(env, "verifier internal error\n"); + if (meta->release_regno) { + verbose(env, "verifier internal error: more than one release argument\n"); return -EFAULT; } - } else if (arg_type_is_mem_ptr(arg_type)) { - expected_type = PTR_TO_STACK; - /* One exception here. In case function allows for NULL to be - * passed in as argument, it's a SCALAR_VALUE type. Final test - * happens during stack boundary checking. - */ - if (register_is_null(reg) && - arg_type == ARG_PTR_TO_MEM_OR_NULL) - /* final test in check_stack_boundary() */; - else if (!type_is_pkt_pointer(type) && - type != PTR_TO_MAP_VALUE && - type != expected_type) - goto err_type; - meta->raw_mode = arg_type == ARG_PTR_TO_UNINIT_MEM; - } else if (arg_type_is_int_ptr(arg_type)) { - expected_type = PTR_TO_STACK; - if (!type_is_pkt_pointer(type) && - type != PTR_TO_MAP_VALUE && - type != expected_type) - goto err_type; - } else { - verbose(env, "unsupported arg_type %d\n", arg_type); - return -EFAULT; + meta->release_regno = regno; + } + + if (reg->ref_obj_id) { + if (meta->ref_obj_id) { + verbose(env, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n", + regno, reg->ref_obj_id, + meta->ref_obj_id); + return -EFAULT; + } + meta->ref_obj_id = reg->ref_obj_id; } - if (arg_type == ARG_CONST_MAP_PTR) { + switch (base_type(arg_type)) { + case ARG_CONST_MAP_PTR: /* bpf_map_xxx(map_ptr) call: remember that map_ptr */ + if (meta->map_ptr) { + /* Use map_uid (which is unique id of inner map) to reject: + * inner_map1 = bpf_map_lookup_elem(outer_map, key1) + * inner_map2 = bpf_map_lookup_elem(outer_map, key2) + * if (inner_map1 && inner_map2) { + * timer = bpf_map_lookup_elem(inner_map1); + * if (timer) + * // mismatch would have been allowed + * bpf_timer_init(timer, inner_map2); + * } + * + * Comparing map_ptr is enough to distinguish normal and outer maps. + */ + if (meta->map_ptr != reg->map_ptr || + meta->map_uid != reg->map_uid) { + verbose(env, + "timer pointer in R1 map_uid=%d doesn't match map pointer in R2 map_uid=%d\n", + meta->map_uid, reg->map_uid); + return -EINVAL; + } + } meta->map_ptr = reg->map_ptr; - } else if (arg_type == ARG_PTR_TO_MAP_KEY) { + meta->map_uid = reg->map_uid; + break; + case ARG_PTR_TO_MAP_KEY: /* bpf_map_xxx(..., map_ptr, ..., key) call: * check that [key, key + map->key_size) are within * stack limits and initialized @@ -3557,10 +6028,11 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 regno, err = check_helper_mem_access(env, regno, meta->map_ptr->key_size, false, NULL); - } else if (arg_type == ARG_PTR_TO_MAP_VALUE || - (arg_type == ARG_PTR_TO_MAP_VALUE_OR_NULL && - !register_is_null(reg)) || - arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE) { + break; + case ARG_PTR_TO_MAP_VALUE: + if (type_may_be_null(arg_type) && register_is_null(reg)) + return 0; + /* bpf_map_xxx(..., map_ptr, ..., value) call: * check [value, value + map->value_size) validity */ @@ -3569,68 +6041,212 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 regno, verbose(env, "invalid map_ptr to access map->value\n"); return -EACCES; } - meta->raw_mode = (arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE); + meta->raw_mode = arg_type & MEM_UNINIT; err = check_helper_mem_access(env, regno, meta->map_ptr->value_size, false, meta); - } else if (arg_type_is_mem_size(arg_type)) { - bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO); - - /* remember the mem_size which may be used later - * to refine return values. + break; + case ARG_PTR_TO_PERCPU_BTF_ID: + if (!reg->btf_id) { + verbose(env, "Helper has invalid btf_id in R%d\n", regno); + return -EACCES; + } + meta->ret_btf = reg->btf; + meta->ret_btf_id = reg->btf_id; + break; + case ARG_PTR_TO_SPIN_LOCK: + if (meta->func_id == BPF_FUNC_spin_lock) { + if (process_spin_lock(env, regno, true)) + return -EACCES; + } else if (meta->func_id == BPF_FUNC_spin_unlock) { + if (process_spin_lock(env, regno, false)) + return -EACCES; + } else { + verbose(env, "verifier internal error\n"); + return -EFAULT; + } + break; + case ARG_PTR_TO_TIMER: + if (process_timer_func(env, regno, meta)) + return -EACCES; + break; + case ARG_PTR_TO_FUNC: + meta->subprogno = reg->subprogno; + break; + case ARG_PTR_TO_MEM: + /* The access to this pointer is only checked when we hit the + * next is_mem_size argument below. */ - meta->msize_smax_value = reg->smax_value; - meta->msize_umax_value = reg->umax_value; - - /* The register is SCALAR_VALUE; the access check - * happens using its boundaries. + meta->raw_mode = arg_type & MEM_UNINIT; + if (arg_type & MEM_FIXED_SIZE) { + err = check_helper_mem_access(env, regno, + fn->arg_size[arg], false, + meta); + } + break; + case ARG_CONST_SIZE: + err = check_mem_size_reg(env, reg, regno, false, meta); + break; + case ARG_CONST_SIZE_OR_ZERO: + err = check_mem_size_reg(env, reg, regno, true, meta); + break; + case ARG_PTR_TO_DYNPTR: + /* We only need to check for initialized / uninitialized helper + * dynptr args if the dynptr is not PTR_TO_DYNPTR, as the + * assumption is that if it is, that a helper function + * initialized the dynptr on behalf of the BPF program. */ - if (!tnum_is_const(reg->var_off)) - /* For unprivileged variable accesses, disable raw - * mode so that the program is required to - * initialize all the memory that the helper could - * just partially fill up. + if (base_type(reg->type) == PTR_TO_DYNPTR) + break; + if (arg_type & MEM_UNINIT) { + if (!is_dynptr_reg_valid_uninit(env, reg)) { + verbose(env, "Dynptr has to be an uninitialized dynptr\n"); + return -EINVAL; + } + + /* We only support one dynptr being uninitialized at the moment, + * which is sufficient for the helper functions we have right now. */ - meta = NULL; + if (meta->uninit_dynptr_regno) { + verbose(env, "verifier internal error: multiple uninitialized dynptr args\n"); + return -EFAULT; + } - if (reg->smin_value < 0) { - verbose(env, "R%d min value is negative, either use unsigned or 'var &= const'\n", - regno); - return -EACCES; - } + meta->uninit_dynptr_regno = regno; + } else if (!is_dynptr_reg_valid_init(env, reg)) { + verbose(env, + "Expected an initialized dynptr as arg #%d\n", + arg + 1); + return -EINVAL; + } else if (!is_dynptr_type_expected(env, reg, arg_type)) { + const char *err_extra = ""; - if (reg->umin_value == 0) { - err = check_helper_mem_access(env, regno - 1, 0, - zero_size_allowed, - meta); - if (err) - return err; + switch (arg_type & DYNPTR_TYPE_FLAG_MASK) { + case DYNPTR_TYPE_LOCAL: + err_extra = "local"; + break; + case DYNPTR_TYPE_RINGBUF: + err_extra = "ringbuf"; + break; + default: + err_extra = "<unknown>"; + break; + } + verbose(env, + "Expected a dynptr of type %s as arg #%d\n", + err_extra, arg + 1); + return -EINVAL; } - - if (reg->umax_value >= BPF_MAX_VAR_SIZ) { - verbose(env, "R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n", + break; + case ARG_CONST_ALLOC_SIZE_OR_ZERO: + if (!tnum_is_const(reg->var_off)) { + verbose(env, "R%d is not a known constant'\n", regno); return -EACCES; } - err = check_helper_mem_access(env, regno - 1, - reg->umax_value, - zero_size_allowed, meta); - if (!err) - err = mark_chain_precision(env, regno); - } else if (arg_type_is_int_ptr(arg_type)) { + meta->mem_size = reg->var_off.value; + err = mark_chain_precision(env, regno); + if (err) + return err; + break; + case ARG_PTR_TO_INT: + case ARG_PTR_TO_LONG: + { int size = int_ptr_type_to_size(arg_type); err = check_helper_mem_access(env, regno, size, false, meta); if (err) return err; err = check_ptr_alignment(env, reg, 0, size, true); + break; + } + case ARG_PTR_TO_CONST_STR: + { + struct bpf_map *map = reg->map_ptr; + int map_off; + u64 map_addr; + char *str_ptr; + + if (!bpf_map_is_rdonly(map)) { + verbose(env, "R%d does not point to a readonly map'\n", regno); + return -EACCES; + } + + if (!tnum_is_const(reg->var_off)) { + verbose(env, "R%d is not a constant address'\n", regno); + return -EACCES; + } + + if (!map->ops->map_direct_value_addr) { + verbose(env, "no direct value access support for this map type\n"); + return -EACCES; + } + + err = check_map_access(env, regno, reg->off, + map->value_size - reg->off, false, + ACCESS_HELPER); + if (err) + return err; + + map_off = reg->off + reg->var_off.value; + err = map->ops->map_direct_value_addr(map, &map_addr, map_off); + if (err) { + verbose(env, "direct value access on string failed\n"); + return err; + } + + str_ptr = (char *)(long)(map_addr); + if (!strnchr(str_ptr + map_off, map->value_size - map_off, 0)) { + verbose(env, "string is not zero-terminated\n"); + return -EINVAL; + } + break; + } + case ARG_PTR_TO_KPTR: + if (process_kptr_func(env, regno, meta)) + return -EACCES; + break; } return err; -err_type: - verbose(env, "R%d type=%s expected=%s\n", regno, - reg_type_str[type], reg_type_str[expected_type]); - return -EACCES; +} + +static bool may_update_sockmap(struct bpf_verifier_env *env, int func_id) +{ + enum bpf_attach_type eatype = env->prog->expected_attach_type; + enum bpf_prog_type type = resolve_prog_type(env->prog); + + if (func_id != BPF_FUNC_map_update_elem) + return false; + + /* It's not possible to get access to a locked struct sock in these + * contexts, so updating is safe. + */ + switch (type) { + case BPF_PROG_TYPE_TRACING: + if (eatype == BPF_TRACE_ITER) + return true; + break; + case BPF_PROG_TYPE_SOCKET_FILTER: + case BPF_PROG_TYPE_SCHED_CLS: + case BPF_PROG_TYPE_SCHED_ACT: + case BPF_PROG_TYPE_XDP: + case BPF_PROG_TYPE_SK_REUSEPORT: + case BPF_PROG_TYPE_FLOW_DISSECTOR: + case BPF_PROG_TYPE_SK_LOOKUP: + return true; + default: + break; + } + + verbose(env, "cannot update sockmap in this context\n"); + return false; +} + +static bool allow_tail_call_in_subprogs(struct bpf_verifier_env *env) +{ + return env->prog->jit_requested && + bpf_jit_supports_subprog_tailcalls(); } static int check_map_func_compatibility(struct bpf_verifier_env *env, @@ -3649,7 +6265,21 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env, if (func_id != BPF_FUNC_perf_event_read && func_id != BPF_FUNC_perf_event_output && func_id != BPF_FUNC_skb_output && - func_id != BPF_FUNC_perf_event_read_value) + func_id != BPF_FUNC_perf_event_read_value && + func_id != BPF_FUNC_xdp_output) + goto error; + break; + case BPF_MAP_TYPE_RINGBUF: + if (func_id != BPF_FUNC_ringbuf_output && + func_id != BPF_FUNC_ringbuf_reserve && + func_id != BPF_FUNC_ringbuf_query && + func_id != BPF_FUNC_ringbuf_reserve_dynptr && + func_id != BPF_FUNC_ringbuf_submit_dynptr && + func_id != BPF_FUNC_ringbuf_discard_dynptr) + goto error; + break; + case BPF_MAP_TYPE_USER_RINGBUF: + if (func_id != BPF_FUNC_user_ringbuf_drain) goto error; break; case BPF_MAP_TYPE_STACK_TRACE: @@ -3693,14 +6323,20 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env, if (func_id != BPF_FUNC_sk_redirect_map && func_id != BPF_FUNC_sock_map_update && func_id != BPF_FUNC_map_delete_elem && - func_id != BPF_FUNC_msg_redirect_map) + func_id != BPF_FUNC_msg_redirect_map && + func_id != BPF_FUNC_sk_select_reuseport && + func_id != BPF_FUNC_map_lookup_elem && + !may_update_sockmap(env, func_id)) goto error; break; case BPF_MAP_TYPE_SOCKHASH: if (func_id != BPF_FUNC_sk_redirect_hash && func_id != BPF_FUNC_sock_hash_update && func_id != BPF_FUNC_map_delete_elem && - func_id != BPF_FUNC_msg_redirect_hash) + func_id != BPF_FUNC_msg_redirect_hash && + func_id != BPF_FUNC_sk_select_reuseport && + func_id != BPF_FUNC_map_lookup_elem && + !may_update_sockmap(env, func_id)) goto error; break; case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY: @@ -3719,6 +6355,21 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env, func_id != BPF_FUNC_sk_storage_delete) goto error; break; + case BPF_MAP_TYPE_INODE_STORAGE: + if (func_id != BPF_FUNC_inode_storage_get && + func_id != BPF_FUNC_inode_storage_delete) + goto error; + break; + case BPF_MAP_TYPE_TASK_STORAGE: + if (func_id != BPF_FUNC_task_storage_get && + func_id != BPF_FUNC_task_storage_delete) + goto error; + break; + case BPF_MAP_TYPE_BLOOM_FILTER: + if (func_id != BPF_FUNC_map_peek_elem && + func_id != BPF_FUNC_map_push_elem) + goto error; + break; default: break; } @@ -3728,8 +6379,8 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env, case BPF_FUNC_tail_call: if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY) goto error; - if (env->subprog_cnt > 1) { - verbose(env, "tail_calls are not allowed in programs with bpf-to-bpf calls\n"); + if (env->subprog_cnt > 1 && !allow_tail_call_in_subprogs(env)) { + verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n"); return -EINVAL; } break; @@ -3737,9 +6388,23 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env, case BPF_FUNC_perf_event_output: case BPF_FUNC_perf_event_read_value: case BPF_FUNC_skb_output: + case BPF_FUNC_xdp_output: if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) goto error; break; + case BPF_FUNC_ringbuf_output: + case BPF_FUNC_ringbuf_reserve: + case BPF_FUNC_ringbuf_query: + case BPF_FUNC_ringbuf_reserve_dynptr: + case BPF_FUNC_ringbuf_submit_dynptr: + case BPF_FUNC_ringbuf_discard_dynptr: + if (map->map_type != BPF_MAP_TYPE_RINGBUF) + goto error; + break; + case BPF_FUNC_user_ringbuf_drain: + if (map->map_type != BPF_MAP_TYPE_USER_RINGBUF) + goto error; + break; case BPF_FUNC_get_stackid: if (map->map_type != BPF_MAP_TYPE_STACK_TRACE) goto error; @@ -3774,21 +6439,44 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env, goto error; break; case BPF_FUNC_sk_select_reuseport: - if (map->map_type != BPF_MAP_TYPE_REUSEPORT_SOCKARRAY) + if (map->map_type != BPF_MAP_TYPE_REUSEPORT_SOCKARRAY && + map->map_type != BPF_MAP_TYPE_SOCKMAP && + map->map_type != BPF_MAP_TYPE_SOCKHASH) goto error; break; - case BPF_FUNC_map_peek_elem: case BPF_FUNC_map_pop_elem: - case BPF_FUNC_map_push_elem: if (map->map_type != BPF_MAP_TYPE_QUEUE && map->map_type != BPF_MAP_TYPE_STACK) goto error; break; + case BPF_FUNC_map_peek_elem: + case BPF_FUNC_map_push_elem: + if (map->map_type != BPF_MAP_TYPE_QUEUE && + map->map_type != BPF_MAP_TYPE_STACK && + map->map_type != BPF_MAP_TYPE_BLOOM_FILTER) + goto error; + break; + case BPF_FUNC_map_lookup_percpu_elem: + if (map->map_type != BPF_MAP_TYPE_PERCPU_ARRAY && + map->map_type != BPF_MAP_TYPE_PERCPU_HASH && + map->map_type != BPF_MAP_TYPE_LRU_PERCPU_HASH) + goto error; + break; case BPF_FUNC_sk_storage_get: case BPF_FUNC_sk_storage_delete: if (map->map_type != BPF_MAP_TYPE_SK_STORAGE) goto error; break; + case BPF_FUNC_inode_storage_get: + case BPF_FUNC_inode_storage_delete: + if (map->map_type != BPF_MAP_TYPE_INODE_STORAGE) + goto error; + break; + case BPF_FUNC_task_storage_get: + case BPF_FUNC_task_storage_delete: + if (map->map_type != BPF_MAP_TYPE_TASK_STORAGE) + goto error; + break; default: break; } @@ -3822,13 +6510,19 @@ static bool check_raw_mode_ok(const struct bpf_func_proto *fn) return count <= 1; } -static bool check_args_pair_invalid(enum bpf_arg_type arg_curr, - enum bpf_arg_type arg_next) +static bool check_args_pair_invalid(const struct bpf_func_proto *fn, int arg) { - return (arg_type_is_mem_ptr(arg_curr) && - !arg_type_is_mem_size(arg_next)) || - (!arg_type_is_mem_ptr(arg_curr) && - arg_type_is_mem_size(arg_next)); + bool is_fixed = fn->arg_type[arg] & MEM_FIXED_SIZE; + bool has_size = fn->arg_size[arg] != 0; + bool is_next_size = false; + + if (arg + 1 < ARRAY_SIZE(fn->arg_type)) + is_next_size = arg_type_is_mem_size(fn->arg_type[arg + 1]); + + if (base_type(fn->arg_type[arg]) != ARG_PTR_TO_MEM) + return is_next_size; + + return has_size == is_next_size || is_next_size == is_fixed; } static bool check_arg_pair_ok(const struct bpf_func_proto *fn) @@ -3839,97 +6533,79 @@ static bool check_arg_pair_ok(const struct bpf_func_proto *fn) * helper function specification. */ if (arg_type_is_mem_size(fn->arg1_type) || - arg_type_is_mem_ptr(fn->arg5_type) || - check_args_pair_invalid(fn->arg1_type, fn->arg2_type) || - check_args_pair_invalid(fn->arg2_type, fn->arg3_type) || - check_args_pair_invalid(fn->arg3_type, fn->arg4_type) || - check_args_pair_invalid(fn->arg4_type, fn->arg5_type)) + check_args_pair_invalid(fn, 0) || + check_args_pair_invalid(fn, 1) || + check_args_pair_invalid(fn, 2) || + check_args_pair_invalid(fn, 3) || + check_args_pair_invalid(fn, 4)) return false; return true; } -static bool check_refcount_ok(const struct bpf_func_proto *fn, int func_id) +static bool check_btf_id_ok(const struct bpf_func_proto *fn) { - int count = 0; + int i; - if (arg_type_may_be_refcounted(fn->arg1_type)) - count++; - if (arg_type_may_be_refcounted(fn->arg2_type)) - count++; - if (arg_type_may_be_refcounted(fn->arg3_type)) - count++; - if (arg_type_may_be_refcounted(fn->arg4_type)) - count++; - if (arg_type_may_be_refcounted(fn->arg5_type)) - count++; + for (i = 0; i < ARRAY_SIZE(fn->arg_type); i++) { + if (base_type(fn->arg_type[i]) == ARG_PTR_TO_BTF_ID && !fn->arg_btf_id[i]) + return false; - /* A reference acquiring function cannot acquire - * another refcounted ptr. - */ - if (is_acquire_function(func_id) && count) - return false; + if (base_type(fn->arg_type[i]) != ARG_PTR_TO_BTF_ID && fn->arg_btf_id[i] && + /* arg_btf_id and arg_size are in a union. */ + (base_type(fn->arg_type[i]) != ARG_PTR_TO_MEM || + !(fn->arg_type[i] & MEM_FIXED_SIZE))) + return false; + } - /* We only support one arg being unreferenced at the moment, - * which is sufficient for the helper functions we have right now. - */ - return count <= 1; + return true; } static int check_func_proto(const struct bpf_func_proto *fn, int func_id) { return check_raw_mode_ok(fn) && check_arg_pair_ok(fn) && - check_refcount_ok(fn, func_id) ? 0 : -EINVAL; + check_btf_id_ok(fn) ? 0 : -EINVAL; } /* Packet data might have moved, any old PTR_TO_PACKET[_META,_END] * are now invalid, so turn them into unknown SCALAR_VALUE. */ -static void __clear_all_pkt_pointers(struct bpf_verifier_env *env, - struct bpf_func_state *state) +static void clear_all_pkt_pointers(struct bpf_verifier_env *env) { - struct bpf_reg_state *regs = state->regs, *reg; - int i; - - for (i = 0; i < MAX_BPF_REG; i++) - if (reg_is_pkt_pointer_any(®s[i])) - mark_reg_unknown(env, regs, i); + struct bpf_func_state *state; + struct bpf_reg_state *reg; - bpf_for_each_spilled_reg(i, state, reg) { - if (!reg) - continue; + bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({ if (reg_is_pkt_pointer_any(reg)) __mark_reg_unknown(env, reg); - } + })); } -static void clear_all_pkt_pointers(struct bpf_verifier_env *env) -{ - struct bpf_verifier_state *vstate = env->cur_state; - int i; - - for (i = 0; i <= vstate->curframe; i++) - __clear_all_pkt_pointers(env, vstate->frame[i]); -} +enum { + AT_PKT_END = -1, + BEYOND_PKT_END = -2, +}; -static void release_reg_references(struct bpf_verifier_env *env, - struct bpf_func_state *state, - int ref_obj_id) +static void mark_pkt_end(struct bpf_verifier_state *vstate, int regn, bool range_open) { - struct bpf_reg_state *regs = state->regs, *reg; - int i; + struct bpf_func_state *state = vstate->frame[vstate->curframe]; + struct bpf_reg_state *reg = &state->regs[regn]; - for (i = 0; i < MAX_BPF_REG; i++) - if (regs[i].ref_obj_id == ref_obj_id) - mark_reg_unknown(env, regs, i); + if (reg->type != PTR_TO_PACKET) + /* PTR_TO_PACKET_META is not supported yet */ + return; - bpf_for_each_spilled_reg(i, state, reg) { - if (!reg) - continue; - if (reg->ref_obj_id == ref_obj_id) - __mark_reg_unknown(env, reg); - } + /* The 'reg' is pkt > pkt_end or pkt >= pkt_end. + * How far beyond pkt_end it goes is unknown. + * if (!range_open) it's the case of pkt >= pkt_end + * if (range_open) it's the case of pkt > pkt_end + * hence this pointer is at least 1 byte bigger than pkt_end + */ + if (range_open) + reg->range = BEYOND_PKT_END; + else + reg->range = AT_PKT_END; } /* The pointer with the specified id has released its reference to kernel @@ -3938,16 +6614,22 @@ static void release_reg_references(struct bpf_verifier_env *env, static int release_reference(struct bpf_verifier_env *env, int ref_obj_id) { - struct bpf_verifier_state *vstate = env->cur_state; + struct bpf_func_state *state; + struct bpf_reg_state *reg; int err; - int i; err = release_reference_state(cur_func(env), ref_obj_id); if (err) return err; - for (i = 0; i <= vstate->curframe; i++) - release_reg_references(env, vstate->frame[i], ref_obj_id); + bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({ + if (reg->ref_obj_id == ref_obj_id) { + if (!env->allow_ptr_leaks) + __mark_reg_not_init(env, reg); + else + __mark_reg_unknown(env, reg); + } + })); return 0; } @@ -3964,13 +6646,19 @@ static void clear_caller_saved_regs(struct bpf_verifier_env *env, } } -static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, - int *insn_idx) +typedef int (*set_callee_state_fn)(struct bpf_verifier_env *env, + struct bpf_func_state *caller, + struct bpf_func_state *callee, + int insn_idx); + +static int __check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, + int *insn_idx, int subprog, + set_callee_state_fn set_callee_state_cb) { struct bpf_verifier_state *state = env->cur_state; struct bpf_func_info_aux *func_info_aux; struct bpf_func_state *caller, *callee; - int i, err, subprog, target_insn; + int err; bool is_global = false; if (state->curframe + 1 >= MAX_CALL_FRAMES) { @@ -3979,14 +6667,6 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, return -E2BIG; } - target_insn = *insn_idx + insn->imm; - subprog = find_subprog(env, target_insn + 1); - if (subprog < 0) { - verbose(env, "verifier bug. No program starts at insn %d\n", - target_insn + 1); - return -EFAULT; - } - caller = state->frame[state->curframe]; if (state->frame[state->curframe + 1]) { verbose(env, "verifier bug. Frame %d already allocated\n", @@ -3997,7 +6677,7 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, func_info_aux = env->prog->aux->func_info_aux; if (func_info_aux) is_global = func_info_aux[subprog].linkage == BTF_FUNC_GLOBAL; - err = btf_check_func_arg_match(env, subprog, caller->regs); + err = btf_check_subprog_call(env, subprog, caller->regs); if (err == -EFAULT) return err; if (is_global) { @@ -4012,14 +6692,41 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, subprog); clear_caller_saved_regs(env, caller->regs); - /* All global functions return SCALAR_VALUE */ + /* All global functions return a 64-bit SCALAR_VALUE */ mark_reg_unknown(env, caller->regs, BPF_REG_0); + caller->regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG; /* continue with next insn after call */ return 0; } } + if (insn->code == (BPF_JMP | BPF_CALL) && + insn->src_reg == 0 && + insn->imm == BPF_FUNC_timer_set_callback) { + struct bpf_verifier_state *async_cb; + + /* there is no real recursion here. timer callbacks are async */ + env->subprog_info[subprog].is_async_cb = true; + async_cb = push_async_cb(env, env->subprog_info[subprog].start, + *insn_idx, subprog); + if (!async_cb) + return -EFAULT; + callee = async_cb->frame[0]; + callee->async_entry_cnt = caller->async_entry_cnt + 1; + + /* Convert bpf_timer_set_callback() args into timer callback args */ + err = set_callee_state_cb(env, caller, callee, *insn_idx); + if (err) + return err; + + clear_caller_saved_regs(env, caller->regs); + mark_reg_unknown(env, caller->regs, BPF_REG_0); + caller->regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG; + /* continue with next insn after call */ + return 0; + } + callee = kzalloc(sizeof(*callee), GFP_KERNEL); if (!callee) return -ENOMEM; @@ -4036,15 +6743,13 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, subprog /* subprog number within this prog */); /* Transfer references to the callee */ - err = transfer_reference_state(callee, caller); + err = copy_reference_state(callee, caller); if (err) return err; - /* copy r1 - r5 args that callee can access. The copy includes parent - * pointers, which connects us up to the liveness chain - */ - for (i = BPF_REG_1; i <= BPF_REG_5; i++) - callee->regs[i] = caller->regs[i]; + err = set_callee_state_cb(env, caller, callee, *insn_idx); + if (err) + return err; clear_caller_saved_regs(env, caller->regs); @@ -4052,14 +6757,205 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, state->curframe++; /* and go analyze first insn of the callee */ - *insn_idx = target_insn; + *insn_idx = env->subprog_info[subprog].start - 1; if (env->log.level & BPF_LOG_LEVEL) { verbose(env, "caller:\n"); - print_verifier_state(env, caller); + print_verifier_state(env, caller, true); verbose(env, "callee:\n"); - print_verifier_state(env, callee); + print_verifier_state(env, callee, true); + } + return 0; +} + +int map_set_for_each_callback_args(struct bpf_verifier_env *env, + struct bpf_func_state *caller, + struct bpf_func_state *callee) +{ + /* bpf_for_each_map_elem(struct bpf_map *map, void *callback_fn, + * void *callback_ctx, u64 flags); + * callback_fn(struct bpf_map *map, void *key, void *value, + * void *callback_ctx); + */ + callee->regs[BPF_REG_1] = caller->regs[BPF_REG_1]; + + callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY; + __mark_reg_known_zero(&callee->regs[BPF_REG_2]); + callee->regs[BPF_REG_2].map_ptr = caller->regs[BPF_REG_1].map_ptr; + + callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE; + __mark_reg_known_zero(&callee->regs[BPF_REG_3]); + callee->regs[BPF_REG_3].map_ptr = caller->regs[BPF_REG_1].map_ptr; + + /* pointer to stack or null */ + callee->regs[BPF_REG_4] = caller->regs[BPF_REG_3]; + + /* unused */ + __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); + return 0; +} + +static int set_callee_state(struct bpf_verifier_env *env, + struct bpf_func_state *caller, + struct bpf_func_state *callee, int insn_idx) +{ + int i; + + /* copy r1 - r5 args that callee can access. The copy includes parent + * pointers, which connects us up to the liveness chain + */ + for (i = BPF_REG_1; i <= BPF_REG_5; i++) + callee->regs[i] = caller->regs[i]; + return 0; +} + +static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, + int *insn_idx) +{ + int subprog, target_insn; + + target_insn = *insn_idx + insn->imm + 1; + subprog = find_subprog(env, target_insn); + if (subprog < 0) { + verbose(env, "verifier bug. No program starts at insn %d\n", + target_insn); + return -EFAULT; + } + + return __check_func_call(env, insn, insn_idx, subprog, set_callee_state); +} + +static int set_map_elem_callback_state(struct bpf_verifier_env *env, + struct bpf_func_state *caller, + struct bpf_func_state *callee, + int insn_idx) +{ + struct bpf_insn_aux_data *insn_aux = &env->insn_aux_data[insn_idx]; + struct bpf_map *map; + int err; + + if (bpf_map_ptr_poisoned(insn_aux)) { + verbose(env, "tail_call abusing map_ptr\n"); + return -EINVAL; + } + + map = BPF_MAP_PTR(insn_aux->map_ptr_state); + if (!map->ops->map_set_for_each_callback_args || + !map->ops->map_for_each_callback) { + verbose(env, "callback function not allowed for map\n"); + return -ENOTSUPP; } + + err = map->ops->map_set_for_each_callback_args(env, caller, callee); + if (err) + return err; + + callee->in_callback_fn = true; + callee->callback_ret_range = tnum_range(0, 1); + return 0; +} + +static int set_loop_callback_state(struct bpf_verifier_env *env, + struct bpf_func_state *caller, + struct bpf_func_state *callee, + int insn_idx) +{ + /* bpf_loop(u32 nr_loops, void *callback_fn, void *callback_ctx, + * u64 flags); + * callback_fn(u32 index, void *callback_ctx); + */ + callee->regs[BPF_REG_1].type = SCALAR_VALUE; + callee->regs[BPF_REG_2] = caller->regs[BPF_REG_3]; + + /* unused */ + __mark_reg_not_init(env, &callee->regs[BPF_REG_3]); + __mark_reg_not_init(env, &callee->regs[BPF_REG_4]); + __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); + + callee->in_callback_fn = true; + callee->callback_ret_range = tnum_range(0, 1); + return 0; +} + +static int set_timer_callback_state(struct bpf_verifier_env *env, + struct bpf_func_state *caller, + struct bpf_func_state *callee, + int insn_idx) +{ + struct bpf_map *map_ptr = caller->regs[BPF_REG_1].map_ptr; + + /* bpf_timer_set_callback(struct bpf_timer *timer, void *callback_fn); + * callback_fn(struct bpf_map *map, void *key, void *value); + */ + callee->regs[BPF_REG_1].type = CONST_PTR_TO_MAP; + __mark_reg_known_zero(&callee->regs[BPF_REG_1]); + callee->regs[BPF_REG_1].map_ptr = map_ptr; + + callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY; + __mark_reg_known_zero(&callee->regs[BPF_REG_2]); + callee->regs[BPF_REG_2].map_ptr = map_ptr; + + callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE; + __mark_reg_known_zero(&callee->regs[BPF_REG_3]); + callee->regs[BPF_REG_3].map_ptr = map_ptr; + + /* unused */ + __mark_reg_not_init(env, &callee->regs[BPF_REG_4]); + __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); + callee->in_async_callback_fn = true; + callee->callback_ret_range = tnum_range(0, 1); + return 0; +} + +static int set_find_vma_callback_state(struct bpf_verifier_env *env, + struct bpf_func_state *caller, + struct bpf_func_state *callee, + int insn_idx) +{ + /* bpf_find_vma(struct task_struct *task, u64 addr, + * void *callback_fn, void *callback_ctx, u64 flags) + * (callback_fn)(struct task_struct *task, + * struct vm_area_struct *vma, void *callback_ctx); + */ + callee->regs[BPF_REG_1] = caller->regs[BPF_REG_1]; + + callee->regs[BPF_REG_2].type = PTR_TO_BTF_ID; + __mark_reg_known_zero(&callee->regs[BPF_REG_2]); + callee->regs[BPF_REG_2].btf = btf_vmlinux; + callee->regs[BPF_REG_2].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_VMA], + + /* pointer to stack or null */ + callee->regs[BPF_REG_3] = caller->regs[BPF_REG_4]; + + /* unused */ + __mark_reg_not_init(env, &callee->regs[BPF_REG_4]); + __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); + callee->in_callback_fn = true; + callee->callback_ret_range = tnum_range(0, 1); + return 0; +} + +static int set_user_ringbuf_callback_state(struct bpf_verifier_env *env, + struct bpf_func_state *caller, + struct bpf_func_state *callee, + int insn_idx) +{ + /* bpf_user_ringbuf_drain(struct bpf_map *map, void *callback_fn, void + * callback_ctx, u64 flags); + * callback_fn(struct bpf_dynptr_t* dynptr, void *callback_ctx); + */ + __mark_reg_not_init(env, &callee->regs[BPF_REG_0]); + callee->regs[BPF_REG_1].type = PTR_TO_DYNPTR | DYNPTR_TYPE_LOCAL; + __mark_reg_known_zero(&callee->regs[BPF_REG_1]); + callee->regs[BPF_REG_2] = caller->regs[BPF_REG_3]; + + /* unused */ + __mark_reg_not_init(env, &callee->regs[BPF_REG_3]); + __mark_reg_not_init(env, &callee->regs[BPF_REG_4]); + __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); + + callee->in_callback_fn = true; + callee->callback_ret_range = tnum_range(0, 1); return 0; } @@ -4085,20 +6981,41 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) state->curframe--; caller = state->frame[state->curframe]; - /* return to the caller whatever r0 had in the callee */ - caller->regs[BPF_REG_0] = *r0; + if (callee->in_callback_fn) { + /* enforce R0 return value range [0, 1]. */ + struct tnum range = callee->callback_ret_range; - /* Transfer references to the caller */ - err = transfer_reference_state(caller, callee); - if (err) - return err; + if (r0->type != SCALAR_VALUE) { + verbose(env, "R0 not a scalar value\n"); + return -EACCES; + } + if (!tnum_in(range, r0->var_off)) { + verbose_invalid_scalar(env, r0, &range, "callback return", "R0"); + return -EINVAL; + } + } else { + /* return to the caller whatever r0 had in the callee */ + caller->regs[BPF_REG_0] = *r0; + } + + /* callback_fn frame should have released its own additions to parent's + * reference state at this point, or check_reference_leak would + * complain, hence it must be the same as the caller. There is no need + * to copy it back. + */ + if (!callee->in_callback_fn) { + /* Transfer references to the caller */ + err = copy_reference_state(caller, callee); + if (err) + return err; + } *insn_idx = callee->callsite + 1; if (env->log.level & BPF_LOG_LEVEL) { verbose(env, "returning from callee:\n"); - print_verifier_state(env, callee); + print_verifier_state(env, callee, true); verbose(env, "to caller at %d:\n", *insn_idx); - print_verifier_state(env, caller); + print_verifier_state(env, caller, true); } /* clear everything in the callee */ free_func_state(callee); @@ -4114,13 +7031,17 @@ static void do_refine_retval_range(struct bpf_reg_state *regs, int ret_type, if (ret_type != RET_INTEGER || (func_id != BPF_FUNC_get_stack && - func_id != BPF_FUNC_probe_read_str)) + func_id != BPF_FUNC_get_task_stack && + func_id != BPF_FUNC_probe_read_str && + func_id != BPF_FUNC_probe_read_kernel_str && + func_id != BPF_FUNC_probe_read_user_str)) return; - ret_reg->smax_value = meta->msize_smax_value; - ret_reg->umax_value = meta->msize_umax_value; - __reg_deduce_bounds(ret_reg); - __reg_bound_offset(ret_reg); + ret_reg->smax_value = meta->msize_max_value; + ret_reg->s32_max_value = meta->msize_max_value; + ret_reg->smin_value = -MAX_ERRNO; + ret_reg->s32_min_value = -MAX_ERRNO; + reg_bounds_sync(ret_reg); } static int @@ -4136,7 +7057,10 @@ record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta, func_id != BPF_FUNC_map_delete_elem && func_id != BPF_FUNC_map_push_elem && func_id != BPF_FUNC_map_pop_elem && - func_id != BPF_FUNC_map_peek_elem) + func_id != BPF_FUNC_map_peek_elem && + func_id != BPF_FUNC_for_each_map_elem && + func_id != BPF_FUNC_redirect_map && + func_id != BPF_FUNC_map_lookup_percpu_elem) return 0; if (map == NULL) { @@ -4159,10 +7083,10 @@ record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta, if (!BPF_MAP_PTR(aux->map_ptr_state)) bpf_map_ptr_store(aux, meta->map_ptr, - meta->map_ptr->unpriv_array); + !meta->map_ptr->bypass_spec_v1); else if (BPF_MAP_PTR(aux->map_ptr_state) != meta->map_ptr) bpf_map_ptr_store(aux, BPF_MAP_PTR_POISON, - meta->map_ptr->unpriv_array); + !meta->map_ptr->bypass_spec_v1); return 0; } @@ -4173,8 +7097,7 @@ record_func_key(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta, struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx]; struct bpf_reg_state *regs = cur_regs(env), *reg; struct bpf_map *map = meta->map_ptr; - struct tnum range; - u64 val; + u64 val, max; int err; if (func_id != BPF_FUNC_tail_call) @@ -4184,10 +7107,11 @@ record_func_key(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta, return -EINVAL; } - range = tnum_range(0, map->max_entries - 1); reg = ®s[BPF_REG_3]; + val = reg->var_off.value; + max = map->max_entries; - if (!register_is_const(reg) || !tnum_in(range, reg->var_off)) { + if (!(register_is_const(reg) && val < max)) { bpf_map_key_store(aux, BPF_MAP_KEY_POISON); return 0; } @@ -4195,8 +7119,6 @@ record_func_key(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta, err = mark_chain_precision(env, BPF_REG_3); if (err) return err; - - val = reg->var_off.value; if (bpf_map_key_unseen(aux)) bpf_map_key_store(aux, val); else if (!bpf_map_key_poisoned(aux) && @@ -4208,24 +7130,130 @@ record_func_key(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta, static int check_reference_leak(struct bpf_verifier_env *env) { struct bpf_func_state *state = cur_func(env); + bool refs_lingering = false; int i; + if (state->frameno && !state->in_callback_fn) + return 0; + for (i = 0; i < state->acquired_refs; i++) { + if (state->in_callback_fn && state->refs[i].callback_ref != state->frameno) + continue; verbose(env, "Unreleased reference id=%d alloc_insn=%d\n", state->refs[i].id, state->refs[i].insn_idx); + refs_lingering = true; } - return state->acquired_refs ? -EINVAL : 0; + return refs_lingering ? -EINVAL : 0; } -static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn_idx) +static int check_bpf_snprintf_call(struct bpf_verifier_env *env, + struct bpf_reg_state *regs) { + struct bpf_reg_state *fmt_reg = ®s[BPF_REG_3]; + struct bpf_reg_state *data_len_reg = ®s[BPF_REG_5]; + struct bpf_map *fmt_map = fmt_reg->map_ptr; + int err, fmt_map_off, num_args; + u64 fmt_addr; + char *fmt; + + /* data must be an array of u64 */ + if (data_len_reg->var_off.value % 8) + return -EINVAL; + num_args = data_len_reg->var_off.value / 8; + + /* fmt being ARG_PTR_TO_CONST_STR guarantees that var_off is const + * and map_direct_value_addr is set. + */ + fmt_map_off = fmt_reg->off + fmt_reg->var_off.value; + err = fmt_map->ops->map_direct_value_addr(fmt_map, &fmt_addr, + fmt_map_off); + if (err) { + verbose(env, "verifier bug\n"); + return -EFAULT; + } + fmt = (char *)(long)fmt_addr + fmt_map_off; + + /* We are also guaranteed that fmt+fmt_map_off is NULL terminated, we + * can focus on validating the format specifiers. + */ + err = bpf_bprintf_prepare(fmt, UINT_MAX, NULL, NULL, num_args); + if (err < 0) + verbose(env, "Invalid format string\n"); + + return err; +} + +static int check_get_func_ip(struct bpf_verifier_env *env) +{ + enum bpf_prog_type type = resolve_prog_type(env->prog); + int func_id = BPF_FUNC_get_func_ip; + + if (type == BPF_PROG_TYPE_TRACING) { + if (!bpf_prog_has_trampoline(env->prog)) { + verbose(env, "func %s#%d supported only for fentry/fexit/fmod_ret programs\n", + func_id_name(func_id), func_id); + return -ENOTSUPP; + } + return 0; + } else if (type == BPF_PROG_TYPE_KPROBE) { + return 0; + } + + verbose(env, "func %s#%d not supported for program type %d\n", + func_id_name(func_id), func_id, type); + return -ENOTSUPP; +} + +static struct bpf_insn_aux_data *cur_aux(struct bpf_verifier_env *env) +{ + return &env->insn_aux_data[env->insn_idx]; +} + +static bool loop_flag_is_zero(struct bpf_verifier_env *env) +{ + struct bpf_reg_state *regs = cur_regs(env); + struct bpf_reg_state *reg = ®s[BPF_REG_4]; + bool reg_is_null = register_is_null(reg); + + if (reg_is_null) + mark_chain_precision(env, BPF_REG_4); + + return reg_is_null; +} + +static void update_loop_inline_state(struct bpf_verifier_env *env, u32 subprogno) +{ + struct bpf_loop_inline_state *state = &cur_aux(env)->loop_inline_state; + + if (!state->initialized) { + state->initialized = 1; + state->fit_for_inline = loop_flag_is_zero(env); + state->callback_subprogno = subprogno; + return; + } + + if (!state->fit_for_inline) + return; + + state->fit_for_inline = (loop_flag_is_zero(env) && + state->callback_subprogno == subprogno); +} + +static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn, + int *insn_idx_p) +{ + enum bpf_prog_type prog_type = resolve_prog_type(env->prog); const struct bpf_func_proto *fn = NULL; + enum bpf_return_type ret_type; + enum bpf_type_flag ret_flag; struct bpf_reg_state *regs; struct bpf_call_arg_meta meta; + int insn_idx = *insn_idx_p; bool changes_data; - int i, err; + int i, err, func_id; /* find function prototype */ + func_id = insn->imm; if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) { verbose(env, "invalid func %s#%d\n", func_id_name(func_id), func_id); @@ -4246,6 +7274,11 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn return -EINVAL; } + if (fn->allowed && !fn->allowed(env->prog)) { + verbose(env, "helper call is not allowed in probe\n"); + return -EINVAL; + } + /* With LD_ABS/IND some JITs save/restore skb from r1. */ changes_data = bpf_helper_changes_pkt_data(fn->func); if (changes_data && fn->arg1_type != ARG_PTR_TO_CTX) { @@ -4266,11 +7299,8 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn meta.func_id = func_id; /* check args */ - for (i = 0; i < 5; i++) { - err = btf_resolve_helper_id(&env->log, fn, i); - if (err > 0) - meta.btf_id = err; - err = check_func_arg(env, BPF_REG_1 + i, fn->arg_type[i], &meta); + for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) { + err = check_func_arg(env, i, &meta, fn); if (err) return err; } @@ -4293,14 +7323,35 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn return err; } - if (func_id == BPF_FUNC_tail_call) { - err = check_reference_leak(env); - if (err) { - verbose(env, "tail_call would lead to reference leak\n"); - return err; + regs = cur_regs(env); + + if (meta.uninit_dynptr_regno) { + /* we write BPF_DW bits (8 bytes) at a time */ + for (i = 0; i < BPF_DYNPTR_SIZE; i += 8) { + err = check_mem_access(env, insn_idx, meta.uninit_dynptr_regno, + i, BPF_DW, BPF_WRITE, -1, false); + if (err) + return err; } - } else if (is_release_function(func_id)) { - err = release_reference(env, meta.ref_obj_id); + + err = mark_stack_slots_dynptr(env, ®s[meta.uninit_dynptr_regno], + fn->arg_type[meta.uninit_dynptr_regno - BPF_REG_1], + insn_idx); + if (err) + return err; + } + + if (meta.release_regno) { + err = -EINVAL; + if (arg_type_is_dynptr(fn->arg_type[meta.release_regno - BPF_REG_1])) + err = unmark_stack_slots_dynptr(env, ®s[meta.release_regno]); + else if (meta.ref_obj_id) + err = release_reference(env, meta.ref_obj_id); + /* meta.ref_obj_id can only be 0 if register that is meant to be + * released is NULL, which must be > R0. + */ + else if (register_is_null(®s[meta.release_regno])) + err = 0; if (err) { verbose(env, "func %s#%d reference has not been acquired before\n", func_id_name(func_id), func_id); @@ -4308,17 +7359,94 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn } } - regs = cur_regs(env); + switch (func_id) { + case BPF_FUNC_tail_call: + err = check_reference_leak(env); + if (err) { + verbose(env, "tail_call would lead to reference leak\n"); + return err; + } + break; + case BPF_FUNC_get_local_storage: + /* check that flags argument in get_local_storage(map, flags) is 0, + * this is required because get_local_storage() can't return an error. + */ + if (!register_is_null(®s[BPF_REG_2])) { + verbose(env, "get_local_storage() doesn't support non-zero flags\n"); + return -EINVAL; + } + break; + case BPF_FUNC_for_each_map_elem: + err = __check_func_call(env, insn, insn_idx_p, meta.subprogno, + set_map_elem_callback_state); + break; + case BPF_FUNC_timer_set_callback: + err = __check_func_call(env, insn, insn_idx_p, meta.subprogno, + set_timer_callback_state); + break; + case BPF_FUNC_find_vma: + err = __check_func_call(env, insn, insn_idx_p, meta.subprogno, + set_find_vma_callback_state); + break; + case BPF_FUNC_snprintf: + err = check_bpf_snprintf_call(env, regs); + break; + case BPF_FUNC_loop: + update_loop_inline_state(env, meta.subprogno); + err = __check_func_call(env, insn, insn_idx_p, meta.subprogno, + set_loop_callback_state); + break; + case BPF_FUNC_dynptr_from_mem: + if (regs[BPF_REG_1].type != PTR_TO_MAP_VALUE) { + verbose(env, "Unsupported reg type %s for bpf_dynptr_from_mem data\n", + reg_type_str(env, regs[BPF_REG_1].type)); + return -EACCES; + } + break; + case BPF_FUNC_set_retval: + if (prog_type == BPF_PROG_TYPE_LSM && + env->prog->expected_attach_type == BPF_LSM_CGROUP) { + if (!env->prog->aux->attach_func_proto->type) { + /* Make sure programs that attach to void + * hooks don't try to modify return value. + */ + verbose(env, "BPF_LSM_CGROUP that attach to void LSM hooks can't modify return value!\n"); + return -EINVAL; + } + } + break; + case BPF_FUNC_dynptr_data: + for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) { + if (arg_type_is_dynptr(fn->arg_type[i])) { + struct bpf_reg_state *reg = ®s[BPF_REG_1 + i]; + + if (meta.ref_obj_id) { + verbose(env, "verifier internal error: meta.ref_obj_id already set\n"); + return -EFAULT; + } - /* check that flags argument in get_local_storage(map, flags) is 0, - * this is required because get_local_storage() can't return an error. - */ - if (func_id == BPF_FUNC_get_local_storage && - !register_is_null(®s[BPF_REG_2])) { - verbose(env, "get_local_storage() doesn't support non-zero flags\n"); - return -EINVAL; + if (base_type(reg->type) != PTR_TO_DYNPTR) + /* Find the id of the dynptr we're + * tracking the reference of + */ + meta.ref_obj_id = stack_slot_get_id(env, reg); + break; + } + } + if (i == MAX_BPF_FUNC_REG_ARGS) { + verbose(env, "verifier internal error: no dynptr in bpf_dynptr_data()\n"); + return -EFAULT; + } + break; + case BPF_FUNC_user_ringbuf_drain: + err = __check_func_call(env, insn, insn_idx_p, meta.subprogno, + set_user_ringbuf_callback_state); + break; } + if (err) + return err; + /* reset caller saved regs */ for (i = 0; i < CALLER_SAVED_REGS; i++) { mark_reg_not_init(env, regs, caller_saved[i]); @@ -4329,13 +7457,18 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG; /* update return register (already marked as written above) */ - if (fn->ret_type == RET_INTEGER) { + ret_type = fn->ret_type; + ret_flag = type_flag(ret_type); + + switch (base_type(ret_type)) { + case RET_INTEGER: /* sets type to SCALAR_VALUE */ mark_reg_unknown(env, regs, BPF_REG_0); - } else if (fn->ret_type == RET_VOID) { + break; + case RET_VOID: regs[BPF_REG_0].type = NOT_INIT; - } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL || - fn->ret_type == RET_PTR_TO_MAP_VALUE) { + break; + case RET_PTR_TO_MAP_VALUE: /* There is no offset yet applied, variable or fixed */ mark_reg_known_zero(env, regs, BPF_REG_0); /* remember map_ptr, so that check_map_access() @@ -4348,36 +7481,114 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn return -EINVAL; } regs[BPF_REG_0].map_ptr = meta.map_ptr; - if (fn->ret_type == RET_PTR_TO_MAP_VALUE) { - regs[BPF_REG_0].type = PTR_TO_MAP_VALUE; - if (map_value_has_spin_lock(meta.map_ptr)) - regs[BPF_REG_0].id = ++env->id_gen; - } else { - regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL; + regs[BPF_REG_0].map_uid = meta.map_uid; + regs[BPF_REG_0].type = PTR_TO_MAP_VALUE | ret_flag; + if (!type_may_be_null(ret_type) && + map_value_has_spin_lock(meta.map_ptr)) { regs[BPF_REG_0].id = ++env->id_gen; } - } else if (fn->ret_type == RET_PTR_TO_SOCKET_OR_NULL) { + break; + case RET_PTR_TO_SOCKET: mark_reg_known_zero(env, regs, BPF_REG_0); - regs[BPF_REG_0].type = PTR_TO_SOCKET_OR_NULL; - regs[BPF_REG_0].id = ++env->id_gen; - } else if (fn->ret_type == RET_PTR_TO_SOCK_COMMON_OR_NULL) { + regs[BPF_REG_0].type = PTR_TO_SOCKET | ret_flag; + break; + case RET_PTR_TO_SOCK_COMMON: mark_reg_known_zero(env, regs, BPF_REG_0); - regs[BPF_REG_0].type = PTR_TO_SOCK_COMMON_OR_NULL; - regs[BPF_REG_0].id = ++env->id_gen; - } else if (fn->ret_type == RET_PTR_TO_TCP_SOCK_OR_NULL) { + regs[BPF_REG_0].type = PTR_TO_SOCK_COMMON | ret_flag; + break; + case RET_PTR_TO_TCP_SOCK: mark_reg_known_zero(env, regs, BPF_REG_0); - regs[BPF_REG_0].type = PTR_TO_TCP_SOCK_OR_NULL; - regs[BPF_REG_0].id = ++env->id_gen; - } else { - verbose(env, "unknown return type %d of func %s#%d\n", - fn->ret_type, func_id_name(func_id), func_id); + regs[BPF_REG_0].type = PTR_TO_TCP_SOCK | ret_flag; + break; + case RET_PTR_TO_ALLOC_MEM: + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag; + regs[BPF_REG_0].mem_size = meta.mem_size; + break; + case RET_PTR_TO_MEM_OR_BTF_ID: + { + const struct btf_type *t; + + mark_reg_known_zero(env, regs, BPF_REG_0); + t = btf_type_skip_modifiers(meta.ret_btf, meta.ret_btf_id, NULL); + if (!btf_type_is_struct(t)) { + u32 tsize; + const struct btf_type *ret; + const char *tname; + + /* resolve the type size of ksym. */ + ret = btf_resolve_size(meta.ret_btf, t, &tsize); + if (IS_ERR(ret)) { + tname = btf_name_by_offset(meta.ret_btf, t->name_off); + verbose(env, "unable to resolve the size of type '%s': %ld\n", + tname, PTR_ERR(ret)); + return -EINVAL; + } + regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag; + regs[BPF_REG_0].mem_size = tsize; + } else { + /* MEM_RDONLY may be carried from ret_flag, but it + * doesn't apply on PTR_TO_BTF_ID. Fold it, otherwise + * it will confuse the check of PTR_TO_BTF_ID in + * check_mem_access(). + */ + ret_flag &= ~MEM_RDONLY; + + regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag; + regs[BPF_REG_0].btf = meta.ret_btf; + regs[BPF_REG_0].btf_id = meta.ret_btf_id; + } + break; + } + case RET_PTR_TO_BTF_ID: + { + struct btf *ret_btf; + int ret_btf_id; + + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag; + if (func_id == BPF_FUNC_kptr_xchg) { + ret_btf = meta.kptr_off_desc->kptr.btf; + ret_btf_id = meta.kptr_off_desc->kptr.btf_id; + } else { + if (fn->ret_btf_id == BPF_PTR_POISON) { + verbose(env, "verifier internal error:"); + verbose(env, "func %s has non-overwritten BPF_PTR_POISON return type\n", + func_id_name(func_id)); + return -EINVAL; + } + ret_btf = btf_vmlinux; + ret_btf_id = *fn->ret_btf_id; + } + if (ret_btf_id == 0) { + verbose(env, "invalid return type %u of func %s#%d\n", + base_type(ret_type), func_id_name(func_id), + func_id); + return -EINVAL; + } + regs[BPF_REG_0].btf = ret_btf; + regs[BPF_REG_0].btf_id = ret_btf_id; + break; + } + default: + verbose(env, "unknown return type %u of func %s#%d\n", + base_type(ret_type), func_id_name(func_id), func_id); return -EINVAL; } - if (is_ptr_cast_function(func_id)) { + if (type_may_be_null(regs[BPF_REG_0].type)) + regs[BPF_REG_0].id = ++env->id_gen; + + if (helper_multiple_ref_obj_use(func_id, meta.map_ptr)) { + verbose(env, "verifier internal error: func %s#%d sets ref_obj_id more than once\n", + func_id_name(func_id), func_id); + return -EFAULT; + } + + if (is_ptr_cast_function(func_id) || is_dynptr_ref_function(func_id)) { /* For release_reference() */ regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id; - } else if (is_acquire_function(func_id)) { + } else if (is_acquire_function(func_id, meta.map_ptr)) { int id = acquire_reference_state(env, insn_idx); if (id < 0) @@ -4394,7 +7605,9 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn if (err) return err; - if (func_id == BPF_FUNC_get_stack && !env->prog->has_callchain_buf) { + if ((func_id == BPF_FUNC_get_stack || + func_id == BPF_FUNC_get_task_stack) && + !env->prog->has_callchain_buf) { const char *err_str; #ifdef CONFIG_PERF_EVENTS @@ -4412,11 +7625,179 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn env->prog->has_callchain_buf = true; } + if (func_id == BPF_FUNC_get_stackid || func_id == BPF_FUNC_get_stack) + env->prog->call_get_stack = true; + + if (func_id == BPF_FUNC_get_func_ip) { + if (check_get_func_ip(env)) + return -ENOTSUPP; + env->prog->call_get_func_ip = true; + } + if (changes_data) clear_all_pkt_pointers(env); return 0; } +/* mark_btf_func_reg_size() is used when the reg size is determined by + * the BTF func_proto's return value size and argument. + */ +static void mark_btf_func_reg_size(struct bpf_verifier_env *env, u32 regno, + size_t reg_size) +{ + struct bpf_reg_state *reg = &cur_regs(env)[regno]; + + if (regno == BPF_REG_0) { + /* Function return value */ + reg->live |= REG_LIVE_WRITTEN; + reg->subreg_def = reg_size == sizeof(u64) ? + DEF_NOT_SUBREG : env->insn_idx + 1; + } else { + /* Function argument */ + if (reg_size == sizeof(u64)) { + mark_insn_zext(env, reg); + mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64); + } else { + mark_reg_read(env, reg, reg->parent, REG_LIVE_READ32); + } + } +} + +static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, + int *insn_idx_p) +{ + const struct btf_type *t, *func, *func_proto, *ptr_type; + struct bpf_reg_state *regs = cur_regs(env); + struct bpf_kfunc_arg_meta meta = { 0 }; + const char *func_name, *ptr_type_name; + u32 i, nargs, func_id, ptr_type_id; + int err, insn_idx = *insn_idx_p; + const struct btf_param *args; + struct btf *desc_btf; + u32 *kfunc_flags; + bool acq; + + /* skip for now, but return error when we find this in fixup_kfunc_call */ + if (!insn->imm) + return 0; + + desc_btf = find_kfunc_desc_btf(env, insn->off); + if (IS_ERR(desc_btf)) + return PTR_ERR(desc_btf); + + func_id = insn->imm; + func = btf_type_by_id(desc_btf, func_id); + func_name = btf_name_by_offset(desc_btf, func->name_off); + func_proto = btf_type_by_id(desc_btf, func->type); + + kfunc_flags = btf_kfunc_id_set_contains(desc_btf, resolve_prog_type(env->prog), func_id); + if (!kfunc_flags) { + verbose(env, "calling kernel function %s is not allowed\n", + func_name); + return -EACCES; + } + if (*kfunc_flags & KF_DESTRUCTIVE && !capable(CAP_SYS_BOOT)) { + verbose(env, "destructive kfunc calls require CAP_SYS_BOOT capabilities\n"); + return -EACCES; + } + + acq = *kfunc_flags & KF_ACQUIRE; + + meta.flags = *kfunc_flags; + + /* Check the arguments */ + err = btf_check_kfunc_arg_match(env, desc_btf, func_id, regs, &meta); + if (err < 0) + return err; + /* In case of release function, we get register number of refcounted + * PTR_TO_BTF_ID back from btf_check_kfunc_arg_match, do the release now + */ + if (err) { + err = release_reference(env, regs[err].ref_obj_id); + if (err) { + verbose(env, "kfunc %s#%d reference has not been acquired before\n", + func_name, func_id); + return err; + } + } + + for (i = 0; i < CALLER_SAVED_REGS; i++) + mark_reg_not_init(env, regs, caller_saved[i]); + + /* Check return type */ + t = btf_type_skip_modifiers(desc_btf, func_proto->type, NULL); + + if (acq && !btf_type_is_struct_ptr(desc_btf, t)) { + verbose(env, "acquire kernel function does not return PTR_TO_BTF_ID\n"); + return -EINVAL; + } + + if (btf_type_is_scalar(t)) { + mark_reg_unknown(env, regs, BPF_REG_0); + mark_btf_func_reg_size(env, BPF_REG_0, t->size); + } else if (btf_type_is_ptr(t)) { + ptr_type = btf_type_skip_modifiers(desc_btf, t->type, + &ptr_type_id); + if (!btf_type_is_struct(ptr_type)) { + if (!meta.r0_size) { + ptr_type_name = btf_name_by_offset(desc_btf, + ptr_type->name_off); + verbose(env, + "kernel function %s returns pointer type %s %s is not supported\n", + func_name, + btf_type_str(ptr_type), + ptr_type_name); + return -EINVAL; + } + + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].type = PTR_TO_MEM; + regs[BPF_REG_0].mem_size = meta.r0_size; + + if (meta.r0_rdonly) + regs[BPF_REG_0].type |= MEM_RDONLY; + + /* Ensures we don't access the memory after a release_reference() */ + if (meta.ref_obj_id) + regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id; + } else { + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].btf = desc_btf; + regs[BPF_REG_0].type = PTR_TO_BTF_ID; + regs[BPF_REG_0].btf_id = ptr_type_id; + } + if (*kfunc_flags & KF_RET_NULL) { + regs[BPF_REG_0].type |= PTR_MAYBE_NULL; + /* For mark_ptr_or_null_reg, see 93c230e3f5bd6 */ + regs[BPF_REG_0].id = ++env->id_gen; + } + mark_btf_func_reg_size(env, BPF_REG_0, sizeof(void *)); + if (acq) { + int id = acquire_reference_state(env, insn_idx); + + if (id < 0) + return id; + regs[BPF_REG_0].id = id; + regs[BPF_REG_0].ref_obj_id = id; + } + } /* else { add_kfunc_call() ensures it is btf_type_is_void(t) } */ + + nargs = btf_type_vlen(func_proto); + args = (const struct btf_param *)(func_proto + 1); + for (i = 0; i < nargs; i++) { + u32 regno = i + 1; + + t = btf_type_skip_modifiers(desc_btf, args[i].type, NULL); + if (btf_type_is_ptr(t)) + mark_btf_func_reg_size(env, regno, sizeof(void *)); + else + /* scalar. ensured by btf_check_kfunc_arg_match() */ + mark_btf_func_reg_size(env, regno, t->size); + } + + return 0; +} + static bool signed_add_overflows(s64 a, s64 b) { /* Do the add in u64, where overflow is well-defined */ @@ -4427,6 +7808,16 @@ static bool signed_add_overflows(s64 a, s64 b) return res < a; } +static bool signed_add32_overflows(s32 a, s32 b) +{ + /* Do the add in u32, where overflow is well-defined */ + s32 res = (s32)((u32)a + (u32)b); + + if (b < 0) + return res > a; + return res < a; +} + static bool signed_sub_overflows(s64 a, s64 b) { /* Do the sub in u64, where overflow is well-defined */ @@ -4437,6 +7828,16 @@ static bool signed_sub_overflows(s64 a, s64 b) return res > a; } +static bool signed_sub32_overflows(s32 a, s32 b) +{ + /* Do the sub in u32, where overflow is well-defined */ + s32 res = (s32)((u32)a - (u32)b); + + if (b < 0) + return res < a; + return res > a; +} + static bool check_reg_sane_offset(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, enum bpf_reg_type type) @@ -4447,71 +7848,74 @@ static bool check_reg_sane_offset(struct bpf_verifier_env *env, if (known && (val >= BPF_MAX_VAR_OFF || val <= -BPF_MAX_VAR_OFF)) { verbose(env, "math between %s pointer and %lld is not allowed\n", - reg_type_str[type], val); + reg_type_str(env, type), val); return false; } if (reg->off >= BPF_MAX_VAR_OFF || reg->off <= -BPF_MAX_VAR_OFF) { verbose(env, "%s pointer offset %d is not allowed\n", - reg_type_str[type], reg->off); + reg_type_str(env, type), reg->off); return false; } if (smin == S64_MIN) { verbose(env, "math between %s pointer and register with unbounded min value is not allowed\n", - reg_type_str[type]); + reg_type_str(env, type)); return false; } if (smin >= BPF_MAX_VAR_OFF || smin <= -BPF_MAX_VAR_OFF) { verbose(env, "value %lld makes %s pointer be out of bounds\n", - smin, reg_type_str[type]); + smin, reg_type_str(env, type)); return false; } return true; } -static struct bpf_insn_aux_data *cur_aux(struct bpf_verifier_env *env) -{ - return &env->insn_aux_data[env->insn_idx]; -} +enum { + REASON_BOUNDS = -1, + REASON_TYPE = -2, + REASON_PATHS = -3, + REASON_LIMIT = -4, + REASON_STACK = -5, +}; static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg, - u32 *ptr_limit, u8 opcode, bool off_is_neg) + u32 *alu_limit, bool mask_to_left) { - bool mask_to_left = (opcode == BPF_ADD && off_is_neg) || - (opcode == BPF_SUB && !off_is_neg); - u32 off; + u32 max = 0, ptr_limit = 0; switch (ptr_reg->type) { case PTR_TO_STACK: - /* Indirect variable offset stack access is prohibited in - * unprivileged mode so it's not handled here. + /* Offset 0 is out-of-bounds, but acceptable start for the + * left direction, see BPF_REG_FP. Also, unknown scalar + * offset where we would need to deal with min/max bounds is + * currently prohibited for unprivileged. */ - off = ptr_reg->off + ptr_reg->var_off.value; - if (mask_to_left) - *ptr_limit = MAX_BPF_STACK + off; - else - *ptr_limit = -off; - return 0; + max = MAX_BPF_STACK + mask_to_left; + ptr_limit = -(ptr_reg->var_off.value + ptr_reg->off); + break; case PTR_TO_MAP_VALUE: - if (mask_to_left) { - *ptr_limit = ptr_reg->umax_value + ptr_reg->off; - } else { - off = ptr_reg->smin_value + ptr_reg->off; - *ptr_limit = ptr_reg->map_ptr->value_size - off; - } - return 0; + max = ptr_reg->map_ptr->value_size; + ptr_limit = (mask_to_left ? + ptr_reg->smin_value : + ptr_reg->umax_value) + ptr_reg->off; + break; default: - return -EINVAL; + return REASON_TYPE; } + + if (ptr_limit >= max) + return REASON_LIMIT; + *alu_limit = ptr_limit; + return 0; } static bool can_skip_alu_sanitation(const struct bpf_verifier_env *env, const struct bpf_insn *insn) { - return env->allow_ptr_leaks || BPF_SRC(insn->code) == BPF_K; + return env->bypass_spec_v1 || BPF_SRC(insn->code) == BPF_K; } static int update_alu_sanitation_state(struct bpf_insn_aux_data *aux, @@ -4523,9 +7927,9 @@ static int update_alu_sanitation_state(struct bpf_insn_aux_data *aux, if (aux->alu_state && (aux->alu_state != alu_state || aux->alu_limit != alu_limit)) - return -EACCES; + return REASON_PATHS; - /* Corresponding fixup done in fixup_bpf_calls(). */ + /* Corresponding fixup done in do_misc_fixups(). */ aux->alu_state = alu_state; aux->alu_limit = alu_limit; return 0; @@ -4542,19 +7946,55 @@ static int sanitize_val_alu(struct bpf_verifier_env *env, return update_alu_sanitation_state(aux, BPF_ALU_NON_POINTER, 0); } +static bool sanitize_needed(u8 opcode) +{ + return opcode == BPF_ADD || opcode == BPF_SUB; +} + +struct bpf_sanitize_info { + struct bpf_insn_aux_data aux; + bool mask_to_left; +}; + +static struct bpf_verifier_state * +sanitize_speculative_path(struct bpf_verifier_env *env, + const struct bpf_insn *insn, + u32 next_idx, u32 curr_idx) +{ + struct bpf_verifier_state *branch; + struct bpf_reg_state *regs; + + branch = push_stack(env, next_idx, curr_idx, true); + if (branch && insn) { + regs = branch->frame[branch->curframe]->regs; + if (BPF_SRC(insn->code) == BPF_K) { + mark_reg_unknown(env, regs, insn->dst_reg); + } else if (BPF_SRC(insn->code) == BPF_X) { + mark_reg_unknown(env, regs, insn->dst_reg); + mark_reg_unknown(env, regs, insn->src_reg); + } + } + return branch; +} + static int sanitize_ptr_alu(struct bpf_verifier_env *env, struct bpf_insn *insn, const struct bpf_reg_state *ptr_reg, + const struct bpf_reg_state *off_reg, struct bpf_reg_state *dst_reg, - bool off_is_neg) + struct bpf_sanitize_info *info, + const bool commit_window) { + struct bpf_insn_aux_data *aux = commit_window ? cur_aux(env) : &info->aux; struct bpf_verifier_state *vstate = env->cur_state; - struct bpf_insn_aux_data *aux = cur_aux(env); + bool off_is_imm = tnum_is_const(off_reg->var_off); + bool off_is_neg = off_reg->smin_value < 0; bool ptr_is_dst_reg = ptr_reg == dst_reg; u8 opcode = BPF_OP(insn->code); u32 alu_state, alu_limit; struct bpf_reg_state tmp; bool ret; + int err; if (can_skip_alu_sanitation(env, insn)) return 0; @@ -4566,15 +8006,53 @@ static int sanitize_ptr_alu(struct bpf_verifier_env *env, if (vstate->speculative) goto do_sim; - alu_state = off_is_neg ? BPF_ALU_NEG_VALUE : 0; - alu_state |= ptr_is_dst_reg ? - BPF_ALU_SANITIZE_SRC : BPF_ALU_SANITIZE_DST; + if (!commit_window) { + if (!tnum_is_const(off_reg->var_off) && + (off_reg->smin_value < 0) != (off_reg->smax_value < 0)) + return REASON_BOUNDS; - if (retrieve_ptr_limit(ptr_reg, &alu_limit, opcode, off_is_neg)) - return 0; - if (update_alu_sanitation_state(aux, alu_state, alu_limit)) - return -EACCES; + info->mask_to_left = (opcode == BPF_ADD && off_is_neg) || + (opcode == BPF_SUB && !off_is_neg); + } + + err = retrieve_ptr_limit(ptr_reg, &alu_limit, info->mask_to_left); + if (err < 0) + return err; + + if (commit_window) { + /* In commit phase we narrow the masking window based on + * the observed pointer move after the simulated operation. + */ + alu_state = info->aux.alu_state; + alu_limit = abs(info->aux.alu_limit - alu_limit); + } else { + alu_state = off_is_neg ? BPF_ALU_NEG_VALUE : 0; + alu_state |= off_is_imm ? BPF_ALU_IMMEDIATE : 0; + alu_state |= ptr_is_dst_reg ? + BPF_ALU_SANITIZE_SRC : BPF_ALU_SANITIZE_DST; + + /* Limit pruning on unknown scalars to enable deep search for + * potential masking differences from other program paths. + */ + if (!off_is_imm) + env->explore_alu_limits = true; + } + + err = update_alu_sanitation_state(aux, alu_state, alu_limit); + if (err < 0) + return err; do_sim: + /* If we're in commit phase, we're done here given we already + * pushed the truncated dst_reg into the speculative verification + * stack. + * + * Also, when register is a known constant, we rewrite register-based + * operation to immediate-based, and thus do not need masking (and as + * a consequence, do not need to simulate the zero-truncation either). + */ + if (commit_window || off_is_imm) + return 0; + /* Simulate and find potential out-of-bounds access under * speculative execution from truncation as a result of * masking when off was not within expected range. If off @@ -4588,10 +8066,129 @@ do_sim: tmp = *dst_reg; *dst_reg = *ptr_reg; } - ret = push_stack(env, env->insn_idx + 1, env->insn_idx, true); + ret = sanitize_speculative_path(env, NULL, env->insn_idx + 1, + env->insn_idx); if (!ptr_is_dst_reg && ret) *dst_reg = tmp; - return !ret ? -EFAULT : 0; + return !ret ? REASON_STACK : 0; +} + +static void sanitize_mark_insn_seen(struct bpf_verifier_env *env) +{ + struct bpf_verifier_state *vstate = env->cur_state; + + /* If we simulate paths under speculation, we don't update the + * insn as 'seen' such that when we verify unreachable paths in + * the non-speculative domain, sanitize_dead_code() can still + * rewrite/sanitize them. + */ + if (!vstate->speculative) + env->insn_aux_data[env->insn_idx].seen = env->pass_cnt; +} + +static int sanitize_err(struct bpf_verifier_env *env, + const struct bpf_insn *insn, int reason, + const struct bpf_reg_state *off_reg, + const struct bpf_reg_state *dst_reg) +{ + static const char *err = "pointer arithmetic with it prohibited for !root"; + const char *op = BPF_OP(insn->code) == BPF_ADD ? "add" : "sub"; + u32 dst = insn->dst_reg, src = insn->src_reg; + + switch (reason) { + case REASON_BOUNDS: + verbose(env, "R%d has unknown scalar with mixed signed bounds, %s\n", + off_reg == dst_reg ? dst : src, err); + break; + case REASON_TYPE: + verbose(env, "R%d has pointer with unsupported alu operation, %s\n", + off_reg == dst_reg ? src : dst, err); + break; + case REASON_PATHS: + verbose(env, "R%d tried to %s from different maps, paths or scalars, %s\n", + dst, op, err); + break; + case REASON_LIMIT: + verbose(env, "R%d tried to %s beyond pointer bounds, %s\n", + dst, op, err); + break; + case REASON_STACK: + verbose(env, "R%d could not be pushed for speculative verification, %s\n", + dst, err); + break; + default: + verbose(env, "verifier internal error: unknown reason (%d)\n", + reason); + break; + } + + return -EACCES; +} + +/* check that stack access falls within stack limits and that 'reg' doesn't + * have a variable offset. + * + * Variable offset is prohibited for unprivileged mode for simplicity since it + * requires corresponding support in Spectre masking for stack ALU. See also + * retrieve_ptr_limit(). + * + * + * 'off' includes 'reg->off'. + */ +static int check_stack_access_for_ptr_arithmetic( + struct bpf_verifier_env *env, + int regno, + const struct bpf_reg_state *reg, + int off) +{ + if (!tnum_is_const(reg->var_off)) { + char tn_buf[48]; + + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose(env, "R%d variable stack access prohibited for !root, var_off=%s off=%d\n", + regno, tn_buf, off); + return -EACCES; + } + + if (off >= 0 || off < -MAX_BPF_STACK) { + verbose(env, "R%d stack pointer arithmetic goes out of range, " + "prohibited for !root; off=%d\n", regno, off); + return -EACCES; + } + + return 0; +} + +static int sanitize_check_bounds(struct bpf_verifier_env *env, + const struct bpf_insn *insn, + const struct bpf_reg_state *dst_reg) +{ + u32 dst = insn->dst_reg; + + /* For unprivileged we require that resulting offset must be in bounds + * in order to be able to sanitize access later on. + */ + if (env->bypass_spec_v1) + return 0; + + switch (dst_reg->type) { + case PTR_TO_STACK: + if (check_stack_access_for_ptr_arithmetic(env, dst, dst_reg, + dst_reg->off + dst_reg->var_off.value)) + return -EACCES; + break; + case PTR_TO_MAP_VALUE: + if (check_map_access(env, dst, dst_reg->off, 1, false, ACCESS_HELPER)) { + verbose(env, "R%d pointer arithmetic of map value goes out of range, " + "prohibited for !root\n", dst); + return -EACCES; + } + break; + default: + break; + } + + return 0; } /* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off. @@ -4612,8 +8209,9 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, smin_ptr = ptr_reg->smin_value, smax_ptr = ptr_reg->smax_value; u64 umin_val = off_reg->umin_value, umax_val = off_reg->umax_value, umin_ptr = ptr_reg->umin_value, umax_ptr = ptr_reg->umax_value; - u32 dst = insn->dst_reg, src = insn->src_reg; + struct bpf_sanitize_info info = {}; u8 opcode = BPF_OP(insn->code); + u32 dst = insn->dst_reg; int ret; dst_reg = ®s[dst]; @@ -4629,36 +8227,37 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, if (BPF_CLASS(insn->code) != BPF_ALU64) { /* 32-bit ALU ops on pointers produce (meaningless) scalars */ + if (opcode == BPF_SUB && env->allow_ptr_leaks) { + __mark_reg_unknown(env, dst_reg); + return 0; + } + verbose(env, "R%d 32-bit pointer arithmetic prohibited\n", dst); return -EACCES; } - switch (ptr_reg->type) { - case PTR_TO_MAP_VALUE_OR_NULL: + if (ptr_reg->type & PTR_MAYBE_NULL) { verbose(env, "R%d pointer arithmetic on %s prohibited, null-check it first\n", - dst, reg_type_str[ptr_reg->type]); + dst, reg_type_str(env, ptr_reg->type)); return -EACCES; + } + + switch (base_type(ptr_reg->type)) { case CONST_PTR_TO_MAP: + /* smin_val represents the known value */ + if (known && smin_val == 0 && opcode == BPF_ADD) + break; + fallthrough; case PTR_TO_PACKET_END: case PTR_TO_SOCKET: - case PTR_TO_SOCKET_OR_NULL: case PTR_TO_SOCK_COMMON: - case PTR_TO_SOCK_COMMON_OR_NULL: case PTR_TO_TCP_SOCK: - case PTR_TO_TCP_SOCK_OR_NULL: case PTR_TO_XDP_SOCK: verbose(env, "R%d pointer arithmetic on %s prohibited\n", - dst, reg_type_str[ptr_reg->type]); + dst, reg_type_str(env, ptr_reg->type)); return -EACCES; - case PTR_TO_MAP_VALUE: - if (!env->allow_ptr_leaks && !known && (smin_val < 0) != (smax_val < 0)) { - verbose(env, "R%d has unknown scalar with mixed signed bounds, pointer arithmetic with it prohibited for !root\n", - off_reg == dst_reg ? dst : src); - return -EACCES; - } - /* fall-through */ default: break; } @@ -4673,13 +8272,18 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, !check_reg_sane_offset(env, ptr_reg, ptr_reg->type)) return -EINVAL; + /* pointer types do not carry 32-bit bounds at the moment. */ + __mark_reg32_unbounded(dst_reg); + + if (sanitize_needed(opcode)) { + ret = sanitize_ptr_alu(env, insn, ptr_reg, off_reg, dst_reg, + &info, false); + if (ret < 0) + return sanitize_err(env, insn, ret, off_reg, dst_reg); + } + switch (opcode) { case BPF_ADD: - ret = sanitize_ptr_alu(env, insn, ptr_reg, dst_reg, smin_val < 0); - if (ret < 0) { - verbose(env, "R%d tried to add from different maps or paths\n", dst); - return ret; - } /* We can take a fixed offset as long as it doesn't overflow * the s32 'off' field */ @@ -4726,15 +8330,10 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, if (reg_is_pkt_pointer(ptr_reg)) { dst_reg->id = ++env->id_gen; /* something was added to pkt_ptr, set range to zero */ - dst_reg->raw = 0; + memset(&dst_reg->raw, 0, sizeof(dst_reg->raw)); } break; case BPF_SUB: - ret = sanitize_ptr_alu(env, insn, ptr_reg, dst_reg, smin_val < 0); - if (ret < 0) { - verbose(env, "R%d tried to sub from different maps or paths\n", dst); - return ret; - } if (dst_reg == off_reg) { /* scalar -= pointer. Creates an unknown scalar */ verbose(env, "R%d tried to subtract pointer from scalar\n", @@ -4791,7 +8390,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, dst_reg->id = ++env->id_gen; /* something was added to pkt_ptr, set range to zero */ if (smin_val < 0) - dst_reg->raw = 0; + memset(&dst_reg->raw, 0, sizeof(dst_reg->raw)); } break; case BPF_AND: @@ -4810,30 +8409,584 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, if (!check_reg_sane_offset(env, dst_reg, ptr_reg->type)) return -EINVAL; + reg_bounds_sync(dst_reg); + if (sanitize_check_bounds(env, insn, dst_reg) < 0) + return -EACCES; + if (sanitize_needed(opcode)) { + ret = sanitize_ptr_alu(env, insn, dst_reg, off_reg, dst_reg, + &info, true); + if (ret < 0) + return sanitize_err(env, insn, ret, off_reg, dst_reg); + } + + return 0; +} + +static void scalar32_min_max_add(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + s32 smin_val = src_reg->s32_min_value; + s32 smax_val = src_reg->s32_max_value; + u32 umin_val = src_reg->u32_min_value; + u32 umax_val = src_reg->u32_max_value; + + if (signed_add32_overflows(dst_reg->s32_min_value, smin_val) || + signed_add32_overflows(dst_reg->s32_max_value, smax_val)) { + dst_reg->s32_min_value = S32_MIN; + dst_reg->s32_max_value = S32_MAX; + } else { + dst_reg->s32_min_value += smin_val; + dst_reg->s32_max_value += smax_val; + } + if (dst_reg->u32_min_value + umin_val < umin_val || + dst_reg->u32_max_value + umax_val < umax_val) { + dst_reg->u32_min_value = 0; + dst_reg->u32_max_value = U32_MAX; + } else { + dst_reg->u32_min_value += umin_val; + dst_reg->u32_max_value += umax_val; + } +} + +static void scalar_min_max_add(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + s64 smin_val = src_reg->smin_value; + s64 smax_val = src_reg->smax_value; + u64 umin_val = src_reg->umin_value; + u64 umax_val = src_reg->umax_value; + + if (signed_add_overflows(dst_reg->smin_value, smin_val) || + signed_add_overflows(dst_reg->smax_value, smax_val)) { + dst_reg->smin_value = S64_MIN; + dst_reg->smax_value = S64_MAX; + } else { + dst_reg->smin_value += smin_val; + dst_reg->smax_value += smax_val; + } + if (dst_reg->umin_value + umin_val < umin_val || + dst_reg->umax_value + umax_val < umax_val) { + dst_reg->umin_value = 0; + dst_reg->umax_value = U64_MAX; + } else { + dst_reg->umin_value += umin_val; + dst_reg->umax_value += umax_val; + } +} + +static void scalar32_min_max_sub(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + s32 smin_val = src_reg->s32_min_value; + s32 smax_val = src_reg->s32_max_value; + u32 umin_val = src_reg->u32_min_value; + u32 umax_val = src_reg->u32_max_value; + + if (signed_sub32_overflows(dst_reg->s32_min_value, smax_val) || + signed_sub32_overflows(dst_reg->s32_max_value, smin_val)) { + /* Overflow possible, we know nothing */ + dst_reg->s32_min_value = S32_MIN; + dst_reg->s32_max_value = S32_MAX; + } else { + dst_reg->s32_min_value -= smax_val; + dst_reg->s32_max_value -= smin_val; + } + if (dst_reg->u32_min_value < umax_val) { + /* Overflow possible, we know nothing */ + dst_reg->u32_min_value = 0; + dst_reg->u32_max_value = U32_MAX; + } else { + /* Cannot overflow (as long as bounds are consistent) */ + dst_reg->u32_min_value -= umax_val; + dst_reg->u32_max_value -= umin_val; + } +} + +static void scalar_min_max_sub(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + s64 smin_val = src_reg->smin_value; + s64 smax_val = src_reg->smax_value; + u64 umin_val = src_reg->umin_value; + u64 umax_val = src_reg->umax_value; + + if (signed_sub_overflows(dst_reg->smin_value, smax_val) || + signed_sub_overflows(dst_reg->smax_value, smin_val)) { + /* Overflow possible, we know nothing */ + dst_reg->smin_value = S64_MIN; + dst_reg->smax_value = S64_MAX; + } else { + dst_reg->smin_value -= smax_val; + dst_reg->smax_value -= smin_val; + } + if (dst_reg->umin_value < umax_val) { + /* Overflow possible, we know nothing */ + dst_reg->umin_value = 0; + dst_reg->umax_value = U64_MAX; + } else { + /* Cannot overflow (as long as bounds are consistent) */ + dst_reg->umin_value -= umax_val; + dst_reg->umax_value -= umin_val; + } +} + +static void scalar32_min_max_mul(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + s32 smin_val = src_reg->s32_min_value; + u32 umin_val = src_reg->u32_min_value; + u32 umax_val = src_reg->u32_max_value; + if (smin_val < 0 || dst_reg->s32_min_value < 0) { + /* Ain't nobody got time to multiply that sign */ + __mark_reg32_unbounded(dst_reg); + return; + } + /* Both values are positive, so we can work with unsigned and + * copy the result to signed (unless it exceeds S32_MAX). + */ + if (umax_val > U16_MAX || dst_reg->u32_max_value > U16_MAX) { + /* Potential overflow, we know nothing */ + __mark_reg32_unbounded(dst_reg); + return; + } + dst_reg->u32_min_value *= umin_val; + dst_reg->u32_max_value *= umax_val; + if (dst_reg->u32_max_value > S32_MAX) { + /* Overflow possible, we know nothing */ + dst_reg->s32_min_value = S32_MIN; + dst_reg->s32_max_value = S32_MAX; + } else { + dst_reg->s32_min_value = dst_reg->u32_min_value; + dst_reg->s32_max_value = dst_reg->u32_max_value; + } +} + +static void scalar_min_max_mul(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + s64 smin_val = src_reg->smin_value; + u64 umin_val = src_reg->umin_value; + u64 umax_val = src_reg->umax_value; + + if (smin_val < 0 || dst_reg->smin_value < 0) { + /* Ain't nobody got time to multiply that sign */ + __mark_reg64_unbounded(dst_reg); + return; + } + /* Both values are positive, so we can work with unsigned and + * copy the result to signed (unless it exceeds S64_MAX). + */ + if (umax_val > U32_MAX || dst_reg->umax_value > U32_MAX) { + /* Potential overflow, we know nothing */ + __mark_reg64_unbounded(dst_reg); + return; + } + dst_reg->umin_value *= umin_val; + dst_reg->umax_value *= umax_val; + if (dst_reg->umax_value > S64_MAX) { + /* Overflow possible, we know nothing */ + dst_reg->smin_value = S64_MIN; + dst_reg->smax_value = S64_MAX; + } else { + dst_reg->smin_value = dst_reg->umin_value; + dst_reg->smax_value = dst_reg->umax_value; + } +} + +static void scalar32_min_max_and(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + bool src_known = tnum_subreg_is_const(src_reg->var_off); + bool dst_known = tnum_subreg_is_const(dst_reg->var_off); + struct tnum var32_off = tnum_subreg(dst_reg->var_off); + s32 smin_val = src_reg->s32_min_value; + u32 umax_val = src_reg->u32_max_value; + + if (src_known && dst_known) { + __mark_reg32_known(dst_reg, var32_off.value); + return; + } + + /* We get our minimum from the var_off, since that's inherently + * bitwise. Our maximum is the minimum of the operands' maxima. + */ + dst_reg->u32_min_value = var32_off.value; + dst_reg->u32_max_value = min(dst_reg->u32_max_value, umax_val); + if (dst_reg->s32_min_value < 0 || smin_val < 0) { + /* Lose signed bounds when ANDing negative numbers, + * ain't nobody got time for that. + */ + dst_reg->s32_min_value = S32_MIN; + dst_reg->s32_max_value = S32_MAX; + } else { + /* ANDing two positives gives a positive, so safe to + * cast result into s64. + */ + dst_reg->s32_min_value = dst_reg->u32_min_value; + dst_reg->s32_max_value = dst_reg->u32_max_value; + } +} + +static void scalar_min_max_and(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + bool src_known = tnum_is_const(src_reg->var_off); + bool dst_known = tnum_is_const(dst_reg->var_off); + s64 smin_val = src_reg->smin_value; + u64 umax_val = src_reg->umax_value; + + if (src_known && dst_known) { + __mark_reg_known(dst_reg, dst_reg->var_off.value); + return; + } + + /* We get our minimum from the var_off, since that's inherently + * bitwise. Our maximum is the minimum of the operands' maxima. + */ + dst_reg->umin_value = dst_reg->var_off.value; + dst_reg->umax_value = min(dst_reg->umax_value, umax_val); + if (dst_reg->smin_value < 0 || smin_val < 0) { + /* Lose signed bounds when ANDing negative numbers, + * ain't nobody got time for that. + */ + dst_reg->smin_value = S64_MIN; + dst_reg->smax_value = S64_MAX; + } else { + /* ANDing two positives gives a positive, so safe to + * cast result into s64. + */ + dst_reg->smin_value = dst_reg->umin_value; + dst_reg->smax_value = dst_reg->umax_value; + } + /* We may learn something more from the var_off */ __update_reg_bounds(dst_reg); - __reg_deduce_bounds(dst_reg); - __reg_bound_offset(dst_reg); +} - /* For unprivileged we require that resulting offset must be in bounds - * in order to be able to sanitize access later on. +static void scalar32_min_max_or(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + bool src_known = tnum_subreg_is_const(src_reg->var_off); + bool dst_known = tnum_subreg_is_const(dst_reg->var_off); + struct tnum var32_off = tnum_subreg(dst_reg->var_off); + s32 smin_val = src_reg->s32_min_value; + u32 umin_val = src_reg->u32_min_value; + + if (src_known && dst_known) { + __mark_reg32_known(dst_reg, var32_off.value); + return; + } + + /* We get our maximum from the var_off, and our minimum is the + * maximum of the operands' minima */ - if (!env->allow_ptr_leaks) { - if (dst_reg->type == PTR_TO_MAP_VALUE && - check_map_access(env, dst, dst_reg->off, 1, false)) { - verbose(env, "R%d pointer arithmetic of map value goes out of range, " - "prohibited for !root\n", dst); - return -EACCES; - } else if (dst_reg->type == PTR_TO_STACK && - check_stack_access(env, dst_reg, dst_reg->off + - dst_reg->var_off.value, 1)) { - verbose(env, "R%d stack pointer arithmetic goes out of range, " - "prohibited for !root\n", dst); - return -EACCES; - } + dst_reg->u32_min_value = max(dst_reg->u32_min_value, umin_val); + dst_reg->u32_max_value = var32_off.value | var32_off.mask; + if (dst_reg->s32_min_value < 0 || smin_val < 0) { + /* Lose signed bounds when ORing negative numbers, + * ain't nobody got time for that. + */ + dst_reg->s32_min_value = S32_MIN; + dst_reg->s32_max_value = S32_MAX; + } else { + /* ORing two positives gives a positive, so safe to + * cast result into s64. + */ + dst_reg->s32_min_value = dst_reg->u32_min_value; + dst_reg->s32_max_value = dst_reg->u32_max_value; } +} - return 0; +static void scalar_min_max_or(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + bool src_known = tnum_is_const(src_reg->var_off); + bool dst_known = tnum_is_const(dst_reg->var_off); + s64 smin_val = src_reg->smin_value; + u64 umin_val = src_reg->umin_value; + + if (src_known && dst_known) { + __mark_reg_known(dst_reg, dst_reg->var_off.value); + return; + } + + /* We get our maximum from the var_off, and our minimum is the + * maximum of the operands' minima + */ + dst_reg->umin_value = max(dst_reg->umin_value, umin_val); + dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask; + if (dst_reg->smin_value < 0 || smin_val < 0) { + /* Lose signed bounds when ORing negative numbers, + * ain't nobody got time for that. + */ + dst_reg->smin_value = S64_MIN; + dst_reg->smax_value = S64_MAX; + } else { + /* ORing two positives gives a positive, so safe to + * cast result into s64. + */ + dst_reg->smin_value = dst_reg->umin_value; + dst_reg->smax_value = dst_reg->umax_value; + } + /* We may learn something more from the var_off */ + __update_reg_bounds(dst_reg); +} + +static void scalar32_min_max_xor(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + bool src_known = tnum_subreg_is_const(src_reg->var_off); + bool dst_known = tnum_subreg_is_const(dst_reg->var_off); + struct tnum var32_off = tnum_subreg(dst_reg->var_off); + s32 smin_val = src_reg->s32_min_value; + + if (src_known && dst_known) { + __mark_reg32_known(dst_reg, var32_off.value); + return; + } + + /* We get both minimum and maximum from the var32_off. */ + dst_reg->u32_min_value = var32_off.value; + dst_reg->u32_max_value = var32_off.value | var32_off.mask; + + if (dst_reg->s32_min_value >= 0 && smin_val >= 0) { + /* XORing two positive sign numbers gives a positive, + * so safe to cast u32 result into s32. + */ + dst_reg->s32_min_value = dst_reg->u32_min_value; + dst_reg->s32_max_value = dst_reg->u32_max_value; + } else { + dst_reg->s32_min_value = S32_MIN; + dst_reg->s32_max_value = S32_MAX; + } +} + +static void scalar_min_max_xor(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + bool src_known = tnum_is_const(src_reg->var_off); + bool dst_known = tnum_is_const(dst_reg->var_off); + s64 smin_val = src_reg->smin_value; + + if (src_known && dst_known) { + /* dst_reg->var_off.value has been updated earlier */ + __mark_reg_known(dst_reg, dst_reg->var_off.value); + return; + } + + /* We get both minimum and maximum from the var_off. */ + dst_reg->umin_value = dst_reg->var_off.value; + dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask; + + if (dst_reg->smin_value >= 0 && smin_val >= 0) { + /* XORing two positive sign numbers gives a positive, + * so safe to cast u64 result into s64. + */ + dst_reg->smin_value = dst_reg->umin_value; + dst_reg->smax_value = dst_reg->umax_value; + } else { + dst_reg->smin_value = S64_MIN; + dst_reg->smax_value = S64_MAX; + } + + __update_reg_bounds(dst_reg); +} + +static void __scalar32_min_max_lsh(struct bpf_reg_state *dst_reg, + u64 umin_val, u64 umax_val) +{ + /* We lose all sign bit information (except what we can pick + * up from var_off) + */ + dst_reg->s32_min_value = S32_MIN; + dst_reg->s32_max_value = S32_MAX; + /* If we might shift our top bit out, then we know nothing */ + if (umax_val > 31 || dst_reg->u32_max_value > 1ULL << (31 - umax_val)) { + dst_reg->u32_min_value = 0; + dst_reg->u32_max_value = U32_MAX; + } else { + dst_reg->u32_min_value <<= umin_val; + dst_reg->u32_max_value <<= umax_val; + } +} + +static void scalar32_min_max_lsh(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + u32 umax_val = src_reg->u32_max_value; + u32 umin_val = src_reg->u32_min_value; + /* u32 alu operation will zext upper bits */ + struct tnum subreg = tnum_subreg(dst_reg->var_off); + + __scalar32_min_max_lsh(dst_reg, umin_val, umax_val); + dst_reg->var_off = tnum_subreg(tnum_lshift(subreg, umin_val)); + /* Not required but being careful mark reg64 bounds as unknown so + * that we are forced to pick them up from tnum and zext later and + * if some path skips this step we are still safe. + */ + __mark_reg64_unbounded(dst_reg); + __update_reg32_bounds(dst_reg); +} + +static void __scalar64_min_max_lsh(struct bpf_reg_state *dst_reg, + u64 umin_val, u64 umax_val) +{ + /* Special case <<32 because it is a common compiler pattern to sign + * extend subreg by doing <<32 s>>32. In this case if 32bit bounds are + * positive we know this shift will also be positive so we can track + * bounds correctly. Otherwise we lose all sign bit information except + * what we can pick up from var_off. Perhaps we can generalize this + * later to shifts of any length. + */ + if (umin_val == 32 && umax_val == 32 && dst_reg->s32_max_value >= 0) + dst_reg->smax_value = (s64)dst_reg->s32_max_value << 32; + else + dst_reg->smax_value = S64_MAX; + + if (umin_val == 32 && umax_val == 32 && dst_reg->s32_min_value >= 0) + dst_reg->smin_value = (s64)dst_reg->s32_min_value << 32; + else + dst_reg->smin_value = S64_MIN; + + /* If we might shift our top bit out, then we know nothing */ + if (dst_reg->umax_value > 1ULL << (63 - umax_val)) { + dst_reg->umin_value = 0; + dst_reg->umax_value = U64_MAX; + } else { + dst_reg->umin_value <<= umin_val; + dst_reg->umax_value <<= umax_val; + } +} + +static void scalar_min_max_lsh(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + u64 umax_val = src_reg->umax_value; + u64 umin_val = src_reg->umin_value; + + /* scalar64 calc uses 32bit unshifted bounds so must be called first */ + __scalar64_min_max_lsh(dst_reg, umin_val, umax_val); + __scalar32_min_max_lsh(dst_reg, umin_val, umax_val); + + dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val); + /* We may learn something more from the var_off */ + __update_reg_bounds(dst_reg); +} + +static void scalar32_min_max_rsh(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + struct tnum subreg = tnum_subreg(dst_reg->var_off); + u32 umax_val = src_reg->u32_max_value; + u32 umin_val = src_reg->u32_min_value; + + /* BPF_RSH is an unsigned shift. If the value in dst_reg might + * be negative, then either: + * 1) src_reg might be zero, so the sign bit of the result is + * unknown, so we lose our signed bounds + * 2) it's known negative, thus the unsigned bounds capture the + * signed bounds + * 3) the signed bounds cross zero, so they tell us nothing + * about the result + * If the value in dst_reg is known nonnegative, then again the + * unsigned bounds capture the signed bounds. + * Thus, in all cases it suffices to blow away our signed bounds + * and rely on inferring new ones from the unsigned bounds and + * var_off of the result. + */ + dst_reg->s32_min_value = S32_MIN; + dst_reg->s32_max_value = S32_MAX; + + dst_reg->var_off = tnum_rshift(subreg, umin_val); + dst_reg->u32_min_value >>= umax_val; + dst_reg->u32_max_value >>= umin_val; + + __mark_reg64_unbounded(dst_reg); + __update_reg32_bounds(dst_reg); +} + +static void scalar_min_max_rsh(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + u64 umax_val = src_reg->umax_value; + u64 umin_val = src_reg->umin_value; + + /* BPF_RSH is an unsigned shift. If the value in dst_reg might + * be negative, then either: + * 1) src_reg might be zero, so the sign bit of the result is + * unknown, so we lose our signed bounds + * 2) it's known negative, thus the unsigned bounds capture the + * signed bounds + * 3) the signed bounds cross zero, so they tell us nothing + * about the result + * If the value in dst_reg is known nonnegative, then again the + * unsigned bounds capture the signed bounds. + * Thus, in all cases it suffices to blow away our signed bounds + * and rely on inferring new ones from the unsigned bounds and + * var_off of the result. + */ + dst_reg->smin_value = S64_MIN; + dst_reg->smax_value = S64_MAX; + dst_reg->var_off = tnum_rshift(dst_reg->var_off, umin_val); + dst_reg->umin_value >>= umax_val; + dst_reg->umax_value >>= umin_val; + + /* Its not easy to operate on alu32 bounds here because it depends + * on bits being shifted in. Take easy way out and mark unbounded + * so we can recalculate later from tnum. + */ + __mark_reg32_unbounded(dst_reg); + __update_reg_bounds(dst_reg); +} + +static void scalar32_min_max_arsh(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + u64 umin_val = src_reg->u32_min_value; + + /* Upon reaching here, src_known is true and + * umax_val is equal to umin_val. + */ + dst_reg->s32_min_value = (u32)(((s32)dst_reg->s32_min_value) >> umin_val); + dst_reg->s32_max_value = (u32)(((s32)dst_reg->s32_max_value) >> umin_val); + + dst_reg->var_off = tnum_arshift(tnum_subreg(dst_reg->var_off), umin_val, 32); + + /* blow away the dst_reg umin_value/umax_value and rely on + * dst_reg var_off to refine the result. + */ + dst_reg->u32_min_value = 0; + dst_reg->u32_max_value = U32_MAX; + + __mark_reg64_unbounded(dst_reg); + __update_reg32_bounds(dst_reg); +} + +static void scalar_min_max_arsh(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + u64 umin_val = src_reg->umin_value; + + /* Upon reaching here, src_known is true and umax_val is equal + * to umin_val. + */ + dst_reg->smin_value >>= umin_val; + dst_reg->smax_value >>= umin_val; + + dst_reg->var_off = tnum_arshift(dst_reg->var_off, umin_val, 64); + + /* blow away the dst_reg umin_value/umax_value and rely on + * dst_reg var_off to refine the result. + */ + dst_reg->umin_value = 0; + dst_reg->umax_value = U64_MAX; + + /* Its not easy to operate on alu32 bounds here because it depends + * on bits being shifted in from upper 32-bits. Take easy way out + * and mark unbounded so we can recalculate later from tnum. + */ + __mark_reg32_unbounded(dst_reg); + __update_reg_bounds(dst_reg); } /* WARNING: This function does calculations on 64-bit values, but the actual @@ -4847,36 +9000,47 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, { struct bpf_reg_state *regs = cur_regs(env); u8 opcode = BPF_OP(insn->code); - bool src_known, dst_known; + bool src_known; s64 smin_val, smax_val; u64 umin_val, umax_val; + s32 s32_min_val, s32_max_val; + u32 u32_min_val, u32_max_val; u64 insn_bitness = (BPF_CLASS(insn->code) == BPF_ALU64) ? 64 : 32; - u32 dst = insn->dst_reg; + bool alu32 = (BPF_CLASS(insn->code) != BPF_ALU64); int ret; - if (insn_bitness == 32) { - /* Relevant for 32-bit RSH: Information can propagate towards - * LSB, so it isn't sufficient to only truncate the output to - * 32 bits. - */ - coerce_reg_to_size(dst_reg, 4); - coerce_reg_to_size(&src_reg, 4); - } - smin_val = src_reg.smin_value; smax_val = src_reg.smax_value; umin_val = src_reg.umin_value; umax_val = src_reg.umax_value; - src_known = tnum_is_const(src_reg.var_off); - dst_known = tnum_is_const(dst_reg->var_off); - if ((src_known && (smin_val != smax_val || umin_val != umax_val)) || - smin_val > smax_val || umin_val > umax_val) { - /* Taint dst register if offset had invalid bounds derived from - * e.g. dead branches. - */ - __mark_reg_unknown(env, dst_reg); - return 0; + s32_min_val = src_reg.s32_min_value; + s32_max_val = src_reg.s32_max_value; + u32_min_val = src_reg.u32_min_value; + u32_max_val = src_reg.u32_max_value; + + if (alu32) { + src_known = tnum_subreg_is_const(src_reg.var_off); + if ((src_known && + (s32_min_val != s32_max_val || u32_min_val != u32_max_val)) || + s32_min_val > s32_max_val || u32_min_val > u32_max_val) { + /* Taint dst register if offset had invalid bounds + * derived from e.g. dead branches. + */ + __mark_reg_unknown(env, dst_reg); + return 0; + } + } else { + src_known = tnum_is_const(src_reg.var_off); + if ((src_known && + (smin_val != smax_val || umin_val != umax_val)) || + smin_val > smax_val || umin_val > umax_val) { + /* Taint dst register if offset had invalid bounds + * derived from e.g. dead branches. + */ + __mark_reg_unknown(env, dst_reg); + return 0; + } } if (!src_known && @@ -4885,142 +9049,56 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, return 0; } + if (sanitize_needed(opcode)) { + ret = sanitize_val_alu(env, insn); + if (ret < 0) + return sanitize_err(env, insn, ret, NULL, NULL); + } + + /* Calculate sign/unsigned bounds and tnum for alu32 and alu64 bit ops. + * There are two classes of instructions: The first class we track both + * alu32 and alu64 sign/unsigned bounds independently this provides the + * greatest amount of precision when alu operations are mixed with jmp32 + * operations. These operations are BPF_ADD, BPF_SUB, BPF_MUL, BPF_ADD, + * and BPF_OR. This is possible because these ops have fairly easy to + * understand and calculate behavior in both 32-bit and 64-bit alu ops. + * See alu32 verifier tests for examples. The second class of + * operations, BPF_LSH, BPF_RSH, and BPF_ARSH, however are not so easy + * with regards to tracking sign/unsigned bounds because the bits may + * cross subreg boundaries in the alu64 case. When this happens we mark + * the reg unbounded in the subreg bound space and use the resulting + * tnum to calculate an approximation of the sign/unsigned bounds. + */ switch (opcode) { case BPF_ADD: - ret = sanitize_val_alu(env, insn); - if (ret < 0) { - verbose(env, "R%d tried to add from different pointers or scalars\n", dst); - return ret; - } - if (signed_add_overflows(dst_reg->smin_value, smin_val) || - signed_add_overflows(dst_reg->smax_value, smax_val)) { - dst_reg->smin_value = S64_MIN; - dst_reg->smax_value = S64_MAX; - } else { - dst_reg->smin_value += smin_val; - dst_reg->smax_value += smax_val; - } - if (dst_reg->umin_value + umin_val < umin_val || - dst_reg->umax_value + umax_val < umax_val) { - dst_reg->umin_value = 0; - dst_reg->umax_value = U64_MAX; - } else { - dst_reg->umin_value += umin_val; - dst_reg->umax_value += umax_val; - } + scalar32_min_max_add(dst_reg, &src_reg); + scalar_min_max_add(dst_reg, &src_reg); dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off); break; case BPF_SUB: - ret = sanitize_val_alu(env, insn); - if (ret < 0) { - verbose(env, "R%d tried to sub from different pointers or scalars\n", dst); - return ret; - } - if (signed_sub_overflows(dst_reg->smin_value, smax_val) || - signed_sub_overflows(dst_reg->smax_value, smin_val)) { - /* Overflow possible, we know nothing */ - dst_reg->smin_value = S64_MIN; - dst_reg->smax_value = S64_MAX; - } else { - dst_reg->smin_value -= smax_val; - dst_reg->smax_value -= smin_val; - } - if (dst_reg->umin_value < umax_val) { - /* Overflow possible, we know nothing */ - dst_reg->umin_value = 0; - dst_reg->umax_value = U64_MAX; - } else { - /* Cannot overflow (as long as bounds are consistent) */ - dst_reg->umin_value -= umax_val; - dst_reg->umax_value -= umin_val; - } + scalar32_min_max_sub(dst_reg, &src_reg); + scalar_min_max_sub(dst_reg, &src_reg); dst_reg->var_off = tnum_sub(dst_reg->var_off, src_reg.var_off); break; case BPF_MUL: dst_reg->var_off = tnum_mul(dst_reg->var_off, src_reg.var_off); - if (smin_val < 0 || dst_reg->smin_value < 0) { - /* Ain't nobody got time to multiply that sign */ - __mark_reg_unbounded(dst_reg); - __update_reg_bounds(dst_reg); - break; - } - /* Both values are positive, so we can work with unsigned and - * copy the result to signed (unless it exceeds S64_MAX). - */ - if (umax_val > U32_MAX || dst_reg->umax_value > U32_MAX) { - /* Potential overflow, we know nothing */ - __mark_reg_unbounded(dst_reg); - /* (except what we can learn from the var_off) */ - __update_reg_bounds(dst_reg); - break; - } - dst_reg->umin_value *= umin_val; - dst_reg->umax_value *= umax_val; - if (dst_reg->umax_value > S64_MAX) { - /* Overflow possible, we know nothing */ - dst_reg->smin_value = S64_MIN; - dst_reg->smax_value = S64_MAX; - } else { - dst_reg->smin_value = dst_reg->umin_value; - dst_reg->smax_value = dst_reg->umax_value; - } + scalar32_min_max_mul(dst_reg, &src_reg); + scalar_min_max_mul(dst_reg, &src_reg); break; case BPF_AND: - if (src_known && dst_known) { - __mark_reg_known(dst_reg, dst_reg->var_off.value & - src_reg.var_off.value); - break; - } - /* We get our minimum from the var_off, since that's inherently - * bitwise. Our maximum is the minimum of the operands' maxima. - */ dst_reg->var_off = tnum_and(dst_reg->var_off, src_reg.var_off); - dst_reg->umin_value = dst_reg->var_off.value; - dst_reg->umax_value = min(dst_reg->umax_value, umax_val); - if (dst_reg->smin_value < 0 || smin_val < 0) { - /* Lose signed bounds when ANDing negative numbers, - * ain't nobody got time for that. - */ - dst_reg->smin_value = S64_MIN; - dst_reg->smax_value = S64_MAX; - } else { - /* ANDing two positives gives a positive, so safe to - * cast result into s64. - */ - dst_reg->smin_value = dst_reg->umin_value; - dst_reg->smax_value = dst_reg->umax_value; - } - /* We may learn something more from the var_off */ - __update_reg_bounds(dst_reg); + scalar32_min_max_and(dst_reg, &src_reg); + scalar_min_max_and(dst_reg, &src_reg); break; case BPF_OR: - if (src_known && dst_known) { - __mark_reg_known(dst_reg, dst_reg->var_off.value | - src_reg.var_off.value); - break; - } - /* We get our maximum from the var_off, and our minimum is the - * maximum of the operands' minima - */ dst_reg->var_off = tnum_or(dst_reg->var_off, src_reg.var_off); - dst_reg->umin_value = max(dst_reg->umin_value, umin_val); - dst_reg->umax_value = dst_reg->var_off.value | - dst_reg->var_off.mask; - if (dst_reg->smin_value < 0 || smin_val < 0) { - /* Lose signed bounds when ORing negative numbers, - * ain't nobody got time for that. - */ - dst_reg->smin_value = S64_MIN; - dst_reg->smax_value = S64_MAX; - } else { - /* ORing two positives gives a positive, so safe to - * cast result into s64. - */ - dst_reg->smin_value = dst_reg->umin_value; - dst_reg->smax_value = dst_reg->umax_value; - } - /* We may learn something more from the var_off */ - __update_reg_bounds(dst_reg); + scalar32_min_max_or(dst_reg, &src_reg); + scalar_min_max_or(dst_reg, &src_reg); + break; + case BPF_XOR: + dst_reg->var_off = tnum_xor(dst_reg->var_off, src_reg.var_off); + scalar32_min_max_xor(dst_reg, &src_reg); + scalar_min_max_xor(dst_reg, &src_reg); break; case BPF_LSH: if (umax_val >= insn_bitness) { @@ -5030,22 +9108,10 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, mark_reg_unknown(env, regs, insn->dst_reg); break; } - /* We lose all sign bit information (except what we can pick - * up from var_off) - */ - dst_reg->smin_value = S64_MIN; - dst_reg->smax_value = S64_MAX; - /* If we might shift our top bit out, then we know nothing */ - if (dst_reg->umax_value > 1ULL << (63 - umax_val)) { - dst_reg->umin_value = 0; - dst_reg->umax_value = U64_MAX; - } else { - dst_reg->umin_value <<= umin_val; - dst_reg->umax_value <<= umax_val; - } - dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val); - /* We may learn something more from the var_off */ - __update_reg_bounds(dst_reg); + if (alu32) + scalar32_min_max_lsh(dst_reg, &src_reg); + else + scalar_min_max_lsh(dst_reg, &src_reg); break; case BPF_RSH: if (umax_val >= insn_bitness) { @@ -5055,27 +9121,10 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, mark_reg_unknown(env, regs, insn->dst_reg); break; } - /* BPF_RSH is an unsigned shift. If the value in dst_reg might - * be negative, then either: - * 1) src_reg might be zero, so the sign bit of the result is - * unknown, so we lose our signed bounds - * 2) it's known negative, thus the unsigned bounds capture the - * signed bounds - * 3) the signed bounds cross zero, so they tell us nothing - * about the result - * If the value in dst_reg is known nonnegative, then again the - * unsigned bounts capture the signed bounds. - * Thus, in all cases it suffices to blow away our signed bounds - * and rely on inferring new ones from the unsigned bounds and - * var_off of the result. - */ - dst_reg->smin_value = S64_MIN; - dst_reg->smax_value = S64_MAX; - dst_reg->var_off = tnum_rshift(dst_reg->var_off, umin_val); - dst_reg->umin_value >>= umax_val; - dst_reg->umax_value >>= umin_val; - /* We may learn something more from the var_off */ - __update_reg_bounds(dst_reg); + if (alu32) + scalar32_min_max_rsh(dst_reg, &src_reg); + else + scalar_min_max_rsh(dst_reg, &src_reg); break; case BPF_ARSH: if (umax_val >= insn_bitness) { @@ -5085,40 +9134,20 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, mark_reg_unknown(env, regs, insn->dst_reg); break; } - - /* Upon reaching here, src_known is true and - * umax_val is equal to umin_val. - */ - if (insn_bitness == 32) { - dst_reg->smin_value = (u32)(((s32)dst_reg->smin_value) >> umin_val); - dst_reg->smax_value = (u32)(((s32)dst_reg->smax_value) >> umin_val); - } else { - dst_reg->smin_value >>= umin_val; - dst_reg->smax_value >>= umin_val; - } - - dst_reg->var_off = tnum_arshift(dst_reg->var_off, umin_val, - insn_bitness); - - /* blow away the dst_reg umin_value/umax_value and rely on - * dst_reg var_off to refine the result. - */ - dst_reg->umin_value = 0; - dst_reg->umax_value = U64_MAX; - __update_reg_bounds(dst_reg); + if (alu32) + scalar32_min_max_arsh(dst_reg, &src_reg); + else + scalar_min_max_arsh(dst_reg, &src_reg); break; default: mark_reg_unknown(env, regs, insn->dst_reg); break; } - if (BPF_CLASS(insn->code) != BPF_ALU64) { - /* 32-bit ALU ops are (32,32)->32 */ - coerce_reg_to_size(dst_reg, 4); - } - - __reg_deduce_bounds(dst_reg); - __reg_bound_offset(dst_reg); + /* ALU32 ops are zero extended into 64bit register */ + if (alu32) + zext_32_to_64(dst_reg); + reg_bounds_sync(dst_reg); return 0; } @@ -5139,6 +9168,11 @@ static int adjust_reg_min_max_vals(struct bpf_verifier_env *env, src_reg = NULL; if (dst_reg->type != SCALAR_VALUE) ptr_reg = dst_reg; + else + /* Make sure ID is cleared otherwise dst_reg min/max could be + * incorrectly propagated into other registers by find_equal_scalars() + */ + dst_reg->id = 0; if (BPF_SRC(insn->code) == BPF_X) { src_reg = ®s[insn->src_reg]; if (src_reg->type != SCALAR_VALUE) { @@ -5188,12 +9222,12 @@ static int adjust_reg_min_max_vals(struct bpf_verifier_env *env, /* Got here implies adding two SCALAR_VALUEs */ if (WARN_ON_ONCE(ptr_reg)) { - print_verifier_state(env, state); + print_verifier_state(env, state, true); verbose(env, "verifier internal error: unexpected ptr_reg\n"); return -EINVAL; } if (WARN_ON(!src_reg)) { - print_verifier_state(env, state); + print_verifier_state(env, state, true); verbose(env, "verifier internal error: no src_reg\n"); return -EINVAL; } @@ -5209,7 +9243,7 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) if (opcode == BPF_END || opcode == BPF_NEG) { if (opcode == BPF_NEG) { - if (BPF_SRC(insn->code) != 0 || + if (BPF_SRC(insn->code) != BPF_K || insn->src_reg != BPF_REG_0 || insn->off != 0 || insn->imm != 0) { verbose(env, "BPF_NEG uses reserved fields\n"); @@ -5272,6 +9306,12 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) /* case: R1 = R2 * copy register state to dest reg */ + if (src_reg->type == SCALAR_VALUE && !src_reg->id) + /* Assign src and dst registers the same ID + * that will be used by find_equal_scalars() + * to propagate min/max range. + */ + src_reg->id = ++env->id_gen; *dst_reg = *src_reg; dst_reg->live |= REG_LIVE_WRITTEN; dst_reg->subreg_def = DEF_NOT_SUBREG; @@ -5284,13 +9324,19 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) return -EACCES; } else if (src_reg->type == SCALAR_VALUE) { *dst_reg = *src_reg; + /* Make sure ID is cleared otherwise + * dst_reg min/max could be incorrectly + * propagated into src_reg by find_equal_scalars() + */ + dst_reg->id = 0; dst_reg->live |= REG_LIVE_WRITTEN; dst_reg->subreg_def = env->insn_idx + 1; } else { mark_reg_unknown(env, regs, insn->dst_reg); } - coerce_reg_to_size(dst_reg, 4); + zext_32_to_64(dst_reg); + reg_bounds_sync(dst_reg); } } else { /* case: R = imm @@ -5362,35 +9408,14 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) return 0; } -static void __find_good_pkt_pointers(struct bpf_func_state *state, - struct bpf_reg_state *dst_reg, - enum bpf_reg_type type, u16 new_range) -{ - struct bpf_reg_state *reg; - int i; - - for (i = 0; i < MAX_BPF_REG; i++) { - reg = &state->regs[i]; - if (reg->type == type && reg->id == dst_reg->id) - /* keep the maximum range already checked */ - reg->range = max(reg->range, new_range); - } - - bpf_for_each_spilled_reg(i, state, reg) { - if (!reg) - continue; - if (reg->type == type && reg->id == dst_reg->id) - reg->range = max(reg->range, new_range); - } -} - static void find_good_pkt_pointers(struct bpf_verifier_state *vstate, struct bpf_reg_state *dst_reg, enum bpf_reg_type type, bool range_right_open) { - u16 new_range; - int i; + struct bpf_func_state *state; + struct bpf_reg_state *reg; + int new_range; if (dst_reg->off < 0 || (dst_reg->off == 0 && range_right_open)) @@ -5406,7 +9431,7 @@ static void find_good_pkt_pointers(struct bpf_verifier_state *vstate, new_range = dst_reg->off; if (range_right_open) - new_range--; + new_range++; /* Examples for register markings: * @@ -5455,60 +9480,90 @@ static void find_good_pkt_pointers(struct bpf_verifier_state *vstate, * the range won't allow anything. * dst_reg->off is known < MAX_PACKET_OFF, therefore it fits in a u16. */ - for (i = 0; i <= vstate->curframe; i++) - __find_good_pkt_pointers(vstate->frame[i], dst_reg, type, - new_range); + bpf_for_each_reg_in_vstate(vstate, state, reg, ({ + if (reg->type == type && reg->id == dst_reg->id) + /* keep the maximum range already checked */ + reg->range = max(reg->range, new_range); + })); } -/* compute branch direction of the expression "if (reg opcode val) goto target;" - * and return: - * 1 - branch will be taken and "goto target" will be executed - * 0 - branch will not be taken and fall-through to next insn - * -1 - unknown. Example: "if (reg < 5)" is unknown when register value range [0,10] - */ -static int is_branch_taken(struct bpf_reg_state *reg, u64 val, u8 opcode, - bool is_jmp32) +static int is_branch32_taken(struct bpf_reg_state *reg, u32 val, u8 opcode) { - struct bpf_reg_state reg_lo; - s64 sval; + struct tnum subreg = tnum_subreg(reg->var_off); + s32 sval = (s32)val; - if (__is_pointer_value(false, reg)) - return -1; + switch (opcode) { + case BPF_JEQ: + if (tnum_is_const(subreg)) + return !!tnum_equals_const(subreg, val); + break; + case BPF_JNE: + if (tnum_is_const(subreg)) + return !tnum_equals_const(subreg, val); + break; + case BPF_JSET: + if ((~subreg.mask & subreg.value) & val) + return 1; + if (!((subreg.mask | subreg.value) & val)) + return 0; + break; + case BPF_JGT: + if (reg->u32_min_value > val) + return 1; + else if (reg->u32_max_value <= val) + return 0; + break; + case BPF_JSGT: + if (reg->s32_min_value > sval) + return 1; + else if (reg->s32_max_value <= sval) + return 0; + break; + case BPF_JLT: + if (reg->u32_max_value < val) + return 1; + else if (reg->u32_min_value >= val) + return 0; + break; + case BPF_JSLT: + if (reg->s32_max_value < sval) + return 1; + else if (reg->s32_min_value >= sval) + return 0; + break; + case BPF_JGE: + if (reg->u32_min_value >= val) + return 1; + else if (reg->u32_max_value < val) + return 0; + break; + case BPF_JSGE: + if (reg->s32_min_value >= sval) + return 1; + else if (reg->s32_max_value < sval) + return 0; + break; + case BPF_JLE: + if (reg->u32_max_value <= val) + return 1; + else if (reg->u32_min_value > val) + return 0; + break; + case BPF_JSLE: + if (reg->s32_max_value <= sval) + return 1; + else if (reg->s32_min_value > sval) + return 0; + break; + } - if (is_jmp32) { - reg_lo = *reg; - reg = ®_lo; - /* For JMP32, only low 32 bits are compared, coerce_reg_to_size - * could truncate high bits and update umin/umax according to - * information of low bits. - */ - coerce_reg_to_size(reg, 4); - /* smin/smax need special handling. For example, after coerce, - * if smin_value is 0x00000000ffffffffLL, the value is -1 when - * used as operand to JMP32. It is a negative number from s32's - * point of view, while it is a positive number when seen as - * s64. The smin/smax are kept as s64, therefore, when used with - * JMP32, they need to be transformed into s32, then sign - * extended back to s64. - * - * Also, smin/smax were copied from umin/umax. If umin/umax has - * different sign bit, then min/max relationship doesn't - * maintain after casting into s32, for this case, set smin/smax - * to safest range. - */ - if ((reg->umax_value ^ reg->umin_value) & - (1ULL << 31)) { - reg->smin_value = S32_MIN; - reg->smax_value = S32_MAX; - } - reg->smin_value = (s64)(s32)reg->smin_value; - reg->smax_value = (s64)(s32)reg->smax_value; + return -1; +} - val = (u32)val; - sval = (s64)(s32)val; - } else { - sval = (s64)val; - } + +static int is_branch64_taken(struct bpf_reg_state *reg, u64 val, u8 opcode) +{ + s64 sval = (s64)val; switch (opcode) { case BPF_JEQ: @@ -5534,7 +9589,7 @@ static int is_branch_taken(struct bpf_reg_state *reg, u64 val, u8 opcode, case BPF_JSGT: if (reg->smin_value > sval) return 1; - else if (reg->smax_value < sval) + else if (reg->smax_value <= sval) return 0; break; case BPF_JLT: @@ -5578,27 +9633,100 @@ static int is_branch_taken(struct bpf_reg_state *reg, u64 val, u8 opcode, return -1; } -/* Generate min value of the high 32-bit from TNUM info. */ -static u64 gen_hi_min(struct tnum var) +/* compute branch direction of the expression "if (reg opcode val) goto target;" + * and return: + * 1 - branch will be taken and "goto target" will be executed + * 0 - branch will not be taken and fall-through to next insn + * -1 - unknown. Example: "if (reg < 5)" is unknown when register value + * range [0,10] + */ +static int is_branch_taken(struct bpf_reg_state *reg, u64 val, u8 opcode, + bool is_jmp32) { - return var.value & ~0xffffffffULL; + if (__is_pointer_value(false, reg)) { + if (!reg_type_not_null(reg->type)) + return -1; + + /* If pointer is valid tests against zero will fail so we can + * use this to direct branch taken. + */ + if (val != 0) + return -1; + + switch (opcode) { + case BPF_JEQ: + return 0; + case BPF_JNE: + return 1; + default: + return -1; + } + } + + if (is_jmp32) + return is_branch32_taken(reg, val, opcode); + return is_branch64_taken(reg, val, opcode); } -/* Generate max value of the high 32-bit from TNUM info. */ -static u64 gen_hi_max(struct tnum var) +static int flip_opcode(u32 opcode) { - return (var.value | var.mask) & ~0xffffffffULL; + /* How can we transform "a <op> b" into "b <op> a"? */ + static const u8 opcode_flip[16] = { + /* these stay the same */ + [BPF_JEQ >> 4] = BPF_JEQ, + [BPF_JNE >> 4] = BPF_JNE, + [BPF_JSET >> 4] = BPF_JSET, + /* these swap "lesser" and "greater" (L and G in the opcodes) */ + [BPF_JGE >> 4] = BPF_JLE, + [BPF_JGT >> 4] = BPF_JLT, + [BPF_JLE >> 4] = BPF_JGE, + [BPF_JLT >> 4] = BPF_JGT, + [BPF_JSGE >> 4] = BPF_JSLE, + [BPF_JSGT >> 4] = BPF_JSLT, + [BPF_JSLE >> 4] = BPF_JSGE, + [BPF_JSLT >> 4] = BPF_JSGT + }; + return opcode_flip[opcode >> 4]; } -/* Return true if VAL is compared with a s64 sign extended from s32, and they - * are with the same signedness. - */ -static bool cmp_val_with_extended_s64(s64 sval, struct bpf_reg_state *reg) +static int is_pkt_ptr_branch_taken(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg, + u8 opcode) { - return ((s32)sval >= 0 && - reg->smin_value >= 0 && reg->smax_value <= S32_MAX) || - ((s32)sval < 0 && - reg->smax_value <= 0 && reg->smin_value >= S32_MIN); + struct bpf_reg_state *pkt; + + if (src_reg->type == PTR_TO_PACKET_END) { + pkt = dst_reg; + } else if (dst_reg->type == PTR_TO_PACKET_END) { + pkt = src_reg; + opcode = flip_opcode(opcode); + } else { + return -1; + } + + if (pkt->range >= 0) + return -1; + + switch (opcode) { + case BPF_JLE: + /* pkt <= pkt_end */ + fallthrough; + case BPF_JGT: + /* pkt > pkt_end */ + if (pkt->range == BEYOND_PKT_END) + /* pkt has at last one extra byte beyond pkt_end */ + return opcode == BPF_JGT; + break; + case BPF_JLT: + /* pkt < pkt_end */ + fallthrough; + case BPF_JGE: + /* pkt >= pkt_end */ + if (pkt->range == BEYOND_PKT_END || pkt->range == AT_PKT_END) + return opcode == BPF_JGE; + break; + } + return -1; } /* Adjusts the register min/max values in the case that the dst_reg is the @@ -5607,10 +9735,16 @@ static bool cmp_val_with_extended_s64(s64 sval, struct bpf_reg_state *reg) * In JEQ/JNE cases we also adjust the var_off values. */ static void reg_set_min_max(struct bpf_reg_state *true_reg, - struct bpf_reg_state *false_reg, u64 val, + struct bpf_reg_state *false_reg, + u64 val, u32 val32, u8 opcode, bool is_jmp32) { - s64 sval; + struct tnum false_32off = tnum_subreg(false_reg->var_off); + struct tnum false_64off = false_reg->var_off; + struct tnum true_32off = tnum_subreg(true_reg->var_off); + struct tnum true_64off = true_reg->var_off; + s64 sval = (s64)val; + s32 sval32 = (s32)val32; /* If the dst_reg is a pointer, we can't learn anything about its * variable offset from the compare (unless src_reg were a pointer into @@ -5621,225 +9755,156 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg, if (__is_pointer_value(false, false_reg)) return; - val = is_jmp32 ? (u32)val : val; - sval = is_jmp32 ? (s64)(s32)val : (s64)val; - switch (opcode) { + /* JEQ/JNE comparison doesn't change the register equivalence. + * + * r1 = r2; + * if (r1 == 42) goto label; + * ... + * label: // here both r1 and r2 are known to be 42. + * + * Hence when marking register as known preserve it's ID. + */ case BPF_JEQ: + if (is_jmp32) { + __mark_reg32_known(true_reg, val32); + true_32off = tnum_subreg(true_reg->var_off); + } else { + ___mark_reg_known(true_reg, val); + true_64off = true_reg->var_off; + } + break; case BPF_JNE: - { - struct bpf_reg_state *reg = - opcode == BPF_JEQ ? true_reg : false_reg; - - /* For BPF_JEQ, if this is false we know nothing Jon Snow, but - * if it is true we know the value for sure. Likewise for - * BPF_JNE. - */ if (is_jmp32) { - u64 old_v = reg->var_off.value; - u64 hi_mask = ~0xffffffffULL; - - reg->var_off.value = (old_v & hi_mask) | val; - reg->var_off.mask &= hi_mask; + __mark_reg32_known(false_reg, val32); + false_32off = tnum_subreg(false_reg->var_off); } else { - __mark_reg_known(reg, val); + ___mark_reg_known(false_reg, val); + false_64off = false_reg->var_off; } break; - } case BPF_JSET: - false_reg->var_off = tnum_and(false_reg->var_off, - tnum_const(~val)); - if (is_power_of_2(val)) - true_reg->var_off = tnum_or(true_reg->var_off, - tnum_const(val)); + if (is_jmp32) { + false_32off = tnum_and(false_32off, tnum_const(~val32)); + if (is_power_of_2(val32)) + true_32off = tnum_or(true_32off, + tnum_const(val32)); + } else { + false_64off = tnum_and(false_64off, tnum_const(~val)); + if (is_power_of_2(val)) + true_64off = tnum_or(true_64off, + tnum_const(val)); + } break; case BPF_JGE: case BPF_JGT: { - u64 false_umax = opcode == BPF_JGT ? val : val - 1; - u64 true_umin = opcode == BPF_JGT ? val + 1 : val; - if (is_jmp32) { - false_umax += gen_hi_max(false_reg->var_off); - true_umin += gen_hi_min(true_reg->var_off); + u32 false_umax = opcode == BPF_JGT ? val32 : val32 - 1; + u32 true_umin = opcode == BPF_JGT ? val32 + 1 : val32; + + false_reg->u32_max_value = min(false_reg->u32_max_value, + false_umax); + true_reg->u32_min_value = max(true_reg->u32_min_value, + true_umin); + } else { + u64 false_umax = opcode == BPF_JGT ? val : val - 1; + u64 true_umin = opcode == BPF_JGT ? val + 1 : val; + + false_reg->umax_value = min(false_reg->umax_value, false_umax); + true_reg->umin_value = max(true_reg->umin_value, true_umin); } - false_reg->umax_value = min(false_reg->umax_value, false_umax); - true_reg->umin_value = max(true_reg->umin_value, true_umin); break; } case BPF_JSGE: case BPF_JSGT: { - s64 false_smax = opcode == BPF_JSGT ? sval : sval - 1; - s64 true_smin = opcode == BPF_JSGT ? sval + 1 : sval; + if (is_jmp32) { + s32 false_smax = opcode == BPF_JSGT ? sval32 : sval32 - 1; + s32 true_smin = opcode == BPF_JSGT ? sval32 + 1 : sval32; - /* If the full s64 was not sign-extended from s32 then don't - * deduct further info. - */ - if (is_jmp32 && !cmp_val_with_extended_s64(sval, false_reg)) - break; - false_reg->smax_value = min(false_reg->smax_value, false_smax); - true_reg->smin_value = max(true_reg->smin_value, true_smin); + false_reg->s32_max_value = min(false_reg->s32_max_value, false_smax); + true_reg->s32_min_value = max(true_reg->s32_min_value, true_smin); + } else { + s64 false_smax = opcode == BPF_JSGT ? sval : sval - 1; + s64 true_smin = opcode == BPF_JSGT ? sval + 1 : sval; + + false_reg->smax_value = min(false_reg->smax_value, false_smax); + true_reg->smin_value = max(true_reg->smin_value, true_smin); + } break; } case BPF_JLE: case BPF_JLT: { - u64 false_umin = opcode == BPF_JLT ? val : val + 1; - u64 true_umax = opcode == BPF_JLT ? val - 1 : val; - if (is_jmp32) { - false_umin += gen_hi_min(false_reg->var_off); - true_umax += gen_hi_max(true_reg->var_off); + u32 false_umin = opcode == BPF_JLT ? val32 : val32 + 1; + u32 true_umax = opcode == BPF_JLT ? val32 - 1 : val32; + + false_reg->u32_min_value = max(false_reg->u32_min_value, + false_umin); + true_reg->u32_max_value = min(true_reg->u32_max_value, + true_umax); + } else { + u64 false_umin = opcode == BPF_JLT ? val : val + 1; + u64 true_umax = opcode == BPF_JLT ? val - 1 : val; + + false_reg->umin_value = max(false_reg->umin_value, false_umin); + true_reg->umax_value = min(true_reg->umax_value, true_umax); } - false_reg->umin_value = max(false_reg->umin_value, false_umin); - true_reg->umax_value = min(true_reg->umax_value, true_umax); break; } case BPF_JSLE: case BPF_JSLT: { - s64 false_smin = opcode == BPF_JSLT ? sval : sval + 1; - s64 true_smax = opcode == BPF_JSLT ? sval - 1 : sval; + if (is_jmp32) { + s32 false_smin = opcode == BPF_JSLT ? sval32 : sval32 + 1; + s32 true_smax = opcode == BPF_JSLT ? sval32 - 1 : sval32; - if (is_jmp32 && !cmp_val_with_extended_s64(sval, false_reg)) - break; - false_reg->smin_value = max(false_reg->smin_value, false_smin); - true_reg->smax_value = min(true_reg->smax_value, true_smax); + false_reg->s32_min_value = max(false_reg->s32_min_value, false_smin); + true_reg->s32_max_value = min(true_reg->s32_max_value, true_smax); + } else { + s64 false_smin = opcode == BPF_JSLT ? sval : sval + 1; + s64 true_smax = opcode == BPF_JSLT ? sval - 1 : sval; + + false_reg->smin_value = max(false_reg->smin_value, false_smin); + true_reg->smax_value = min(true_reg->smax_value, true_smax); + } break; } default: - break; + return; } - __reg_deduce_bounds(false_reg); - __reg_deduce_bounds(true_reg); - /* We might have learned some bits from the bounds. */ - __reg_bound_offset(false_reg); - __reg_bound_offset(true_reg); if (is_jmp32) { - __reg_bound_offset32(false_reg); - __reg_bound_offset32(true_reg); + false_reg->var_off = tnum_or(tnum_clear_subreg(false_64off), + tnum_subreg(false_32off)); + true_reg->var_off = tnum_or(tnum_clear_subreg(true_64off), + tnum_subreg(true_32off)); + __reg_combine_32_into_64(false_reg); + __reg_combine_32_into_64(true_reg); + } else { + false_reg->var_off = false_64off; + true_reg->var_off = true_64off; + __reg_combine_64_into_32(false_reg); + __reg_combine_64_into_32(true_reg); } - /* Intersecting with the old var_off might have improved our bounds - * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc), - * then new var_off is (0; 0x7f...fc) which improves our umax. - */ - __update_reg_bounds(false_reg); - __update_reg_bounds(true_reg); } /* Same as above, but for the case that dst_reg holds a constant and src_reg is * the variable reg. */ static void reg_set_min_max_inv(struct bpf_reg_state *true_reg, - struct bpf_reg_state *false_reg, u64 val, + struct bpf_reg_state *false_reg, + u64 val, u32 val32, u8 opcode, bool is_jmp32) { - s64 sval; - - if (__is_pointer_value(false, false_reg)) - return; - - val = is_jmp32 ? (u32)val : val; - sval = is_jmp32 ? (s64)(s32)val : (s64)val; - - switch (opcode) { - case BPF_JEQ: - case BPF_JNE: - { - struct bpf_reg_state *reg = - opcode == BPF_JEQ ? true_reg : false_reg; - - if (is_jmp32) { - u64 old_v = reg->var_off.value; - u64 hi_mask = ~0xffffffffULL; - - reg->var_off.value = (old_v & hi_mask) | val; - reg->var_off.mask &= hi_mask; - } else { - __mark_reg_known(reg, val); - } - break; - } - case BPF_JSET: - false_reg->var_off = tnum_and(false_reg->var_off, - tnum_const(~val)); - if (is_power_of_2(val)) - true_reg->var_off = tnum_or(true_reg->var_off, - tnum_const(val)); - break; - case BPF_JGE: - case BPF_JGT: - { - u64 false_umin = opcode == BPF_JGT ? val : val + 1; - u64 true_umax = opcode == BPF_JGT ? val - 1 : val; - - if (is_jmp32) { - false_umin += gen_hi_min(false_reg->var_off); - true_umax += gen_hi_max(true_reg->var_off); - } - false_reg->umin_value = max(false_reg->umin_value, false_umin); - true_reg->umax_value = min(true_reg->umax_value, true_umax); - break; - } - case BPF_JSGE: - case BPF_JSGT: - { - s64 false_smin = opcode == BPF_JSGT ? sval : sval + 1; - s64 true_smax = opcode == BPF_JSGT ? sval - 1 : sval; - - if (is_jmp32 && !cmp_val_with_extended_s64(sval, false_reg)) - break; - false_reg->smin_value = max(false_reg->smin_value, false_smin); - true_reg->smax_value = min(true_reg->smax_value, true_smax); - break; - } - case BPF_JLE: - case BPF_JLT: - { - u64 false_umax = opcode == BPF_JLT ? val : val - 1; - u64 true_umin = opcode == BPF_JLT ? val + 1 : val; - - if (is_jmp32) { - false_umax += gen_hi_max(false_reg->var_off); - true_umin += gen_hi_min(true_reg->var_off); - } - false_reg->umax_value = min(false_reg->umax_value, false_umax); - true_reg->umin_value = max(true_reg->umin_value, true_umin); - break; - } - case BPF_JSLE: - case BPF_JSLT: - { - s64 false_smax = opcode == BPF_JSLT ? sval : sval - 1; - s64 true_smin = opcode == BPF_JSLT ? sval + 1 : sval; - - if (is_jmp32 && !cmp_val_with_extended_s64(sval, false_reg)) - break; - false_reg->smax_value = min(false_reg->smax_value, false_smax); - true_reg->smin_value = max(true_reg->smin_value, true_smin); - break; - } - default: - break; - } - - __reg_deduce_bounds(false_reg); - __reg_deduce_bounds(true_reg); - /* We might have learned some bits from the bounds. */ - __reg_bound_offset(false_reg); - __reg_bound_offset(true_reg); - if (is_jmp32) { - __reg_bound_offset32(false_reg); - __reg_bound_offset32(true_reg); - } - /* Intersecting with the old var_off might have improved our bounds - * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc), - * then new var_off is (0; 0x7f...fc) which improves our umax. + opcode = flip_opcode(opcode); + /* This uses zero as "not present in table"; luckily the zero opcode, + * BPF_JA, can't get here. */ - __update_reg_bounds(false_reg); - __update_reg_bounds(true_reg); + if (opcode) + reg_set_min_max(true_reg, false_reg, val, val32, opcode, is_jmp32); } /* Regs are known to be equal, so intersect their min/max/var_off */ @@ -5856,21 +9921,8 @@ static void __reg_combine_min_max(struct bpf_reg_state *src_reg, dst_reg->smax_value); src_reg->var_off = dst_reg->var_off = tnum_intersect(src_reg->var_off, dst_reg->var_off); - /* We might have learned new bounds from the var_off. */ - __update_reg_bounds(src_reg); - __update_reg_bounds(dst_reg); - /* We might have learned something about the sign bit. */ - __reg_deduce_bounds(src_reg); - __reg_deduce_bounds(dst_reg); - /* We might have learned some bits from the bounds. */ - __reg_bound_offset(src_reg); - __reg_bound_offset(dst_reg); - /* Intersecting with the old var_off might have improved our bounds - * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc), - * then new var_off is (0; 0x7f...fc) which improves our umax. - */ - __update_reg_bounds(src_reg); - __update_reg_bounds(dst_reg); + reg_bounds_sync(src_reg); + reg_bounds_sync(dst_reg); } static void reg_combine_min_max(struct bpf_reg_state *true_src, @@ -5893,46 +9945,35 @@ static void mark_ptr_or_null_reg(struct bpf_func_state *state, struct bpf_reg_state *reg, u32 id, bool is_null) { - if (reg_type_may_be_null(reg->type) && reg->id == id) { - /* Old offset (both fixed and variable parts) should - * have been known-zero, because we don't allow pointer - * arithmetic on pointers that might be NULL. - */ + if (type_may_be_null(reg->type) && reg->id == id && + !WARN_ON_ONCE(!reg->id)) { if (WARN_ON_ONCE(reg->smin_value || reg->smax_value || !tnum_equals_const(reg->var_off, 0) || reg->off)) { - __mark_reg_known_zero(reg); - reg->off = 0; + /* Old offset (both fixed and variable parts) should + * have been known-zero, because we don't allow pointer + * arithmetic on pointers that might be NULL. If we + * see this happening, don't convert the register. + */ + return; } if (is_null) { reg->type = SCALAR_VALUE; - } else if (reg->type == PTR_TO_MAP_VALUE_OR_NULL) { - if (reg->map_ptr->inner_map_meta) { - reg->type = CONST_PTR_TO_MAP; - reg->map_ptr = reg->map_ptr->inner_map_meta; - } else if (reg->map_ptr->map_type == - BPF_MAP_TYPE_XSKMAP) { - reg->type = PTR_TO_XDP_SOCK; - } else { - reg->type = PTR_TO_MAP_VALUE; - } - } else if (reg->type == PTR_TO_SOCKET_OR_NULL) { - reg->type = PTR_TO_SOCKET; - } else if (reg->type == PTR_TO_SOCK_COMMON_OR_NULL) { - reg->type = PTR_TO_SOCK_COMMON; - } else if (reg->type == PTR_TO_TCP_SOCK_OR_NULL) { - reg->type = PTR_TO_TCP_SOCK; - } - if (is_null) { /* We don't need id and ref_obj_id from this point * onwards anymore, thus we should better reset it, * so that state pruning has chances to take effect. */ reg->id = 0; reg->ref_obj_id = 0; - } else if (!reg_may_point_to_spin_lock(reg)) { + + return; + } + + mark_ptr_not_null_reg(reg); + + if (!reg_may_point_to_spin_lock(reg)) { /* For not-NULL ptr, reg->ref_obj_id will be reset - * in release_reg_references(). + * in release_reference(). * * reg->id is still used by spin_lock ptr. Other * than spin_lock ptr type, reg->id can be reset. @@ -5942,22 +9983,6 @@ static void mark_ptr_or_null_reg(struct bpf_func_state *state, } } -static void __mark_ptr_or_null_regs(struct bpf_func_state *state, u32 id, - bool is_null) -{ - struct bpf_reg_state *reg; - int i; - - for (i = 0; i < MAX_BPF_REG; i++) - mark_ptr_or_null_reg(state, &state->regs[i], id, is_null); - - bpf_for_each_spilled_reg(i, state, reg) { - if (!reg) - continue; - mark_ptr_or_null_reg(state, reg, id, is_null); - } -} - /* The logic is similar to find_good_pkt_pointers(), both could eventually * be folded together at some point. */ @@ -5965,10 +9990,9 @@ static void mark_ptr_or_null_regs(struct bpf_verifier_state *vstate, u32 regno, bool is_null) { struct bpf_func_state *state = vstate->frame[vstate->curframe]; - struct bpf_reg_state *regs = state->regs; + struct bpf_reg_state *regs = state->regs, *reg; u32 ref_obj_id = regs[regno].ref_obj_id; u32 id = regs[regno].id; - int i; if (ref_obj_id && ref_obj_id == id && is_null) /* regs[regno] is in the " == NULL" branch. @@ -5977,8 +10001,9 @@ static void mark_ptr_or_null_regs(struct bpf_verifier_state *vstate, u32 regno, */ WARN_ON_ONCE(release_reference_state(state, id)); - for (i = 0; i <= vstate->curframe; i++) - __mark_ptr_or_null_regs(vstate->frame[i], id, is_null); + bpf_for_each_reg_in_vstate(vstate, state, reg, ({ + mark_ptr_or_null_reg(state, reg, id, is_null); + })); } static bool try_match_pkt_pointers(const struct bpf_insn *insn, @@ -6003,6 +10028,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn, /* pkt_data' > pkt_end, pkt_meta' > pkt_data */ find_good_pkt_pointers(this_branch, dst_reg, dst_reg->type, false); + mark_pkt_end(other_branch, insn->dst_reg, true); } else if ((dst_reg->type == PTR_TO_PACKET_END && src_reg->type == PTR_TO_PACKET) || (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && @@ -6010,6 +10036,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn, /* pkt_end > pkt_data', pkt_data > pkt_meta' */ find_good_pkt_pointers(other_branch, src_reg, src_reg->type, true); + mark_pkt_end(this_branch, insn->src_reg, false); } else { return false; } @@ -6022,6 +10049,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn, /* pkt_data' < pkt_end, pkt_meta' < pkt_data */ find_good_pkt_pointers(other_branch, dst_reg, dst_reg->type, true); + mark_pkt_end(this_branch, insn->dst_reg, false); } else if ((dst_reg->type == PTR_TO_PACKET_END && src_reg->type == PTR_TO_PACKET) || (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && @@ -6029,6 +10057,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn, /* pkt_end < pkt_data', pkt_data > pkt_meta' */ find_good_pkt_pointers(this_branch, src_reg, src_reg->type, false); + mark_pkt_end(other_branch, insn->src_reg, true); } else { return false; } @@ -6041,6 +10070,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn, /* pkt_data' >= pkt_end, pkt_meta' >= pkt_data */ find_good_pkt_pointers(this_branch, dst_reg, dst_reg->type, true); + mark_pkt_end(other_branch, insn->dst_reg, false); } else if ((dst_reg->type == PTR_TO_PACKET_END && src_reg->type == PTR_TO_PACKET) || (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && @@ -6048,6 +10078,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn, /* pkt_end >= pkt_data', pkt_data >= pkt_meta' */ find_good_pkt_pointers(other_branch, src_reg, src_reg->type, false); + mark_pkt_end(this_branch, insn->src_reg, true); } else { return false; } @@ -6060,6 +10091,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn, /* pkt_data' <= pkt_end, pkt_meta' <= pkt_data */ find_good_pkt_pointers(other_branch, dst_reg, dst_reg->type, false); + mark_pkt_end(this_branch, insn->dst_reg, true); } else if ((dst_reg->type == PTR_TO_PACKET_END && src_reg->type == PTR_TO_PACKET) || (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && @@ -6067,6 +10099,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn, /* pkt_end <= pkt_data', pkt_data <= pkt_meta' */ find_good_pkt_pointers(this_branch, src_reg, src_reg->type, true); + mark_pkt_end(other_branch, insn->src_reg, false); } else { return false; } @@ -6078,6 +10111,18 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn, return true; } +static void find_equal_scalars(struct bpf_verifier_state *vstate, + struct bpf_reg_state *known_reg) +{ + struct bpf_func_state *state; + struct bpf_reg_state *reg; + + bpf_for_each_reg_in_vstate(vstate, state, reg, ({ + if (reg->type == SCALAR_VALUE && reg->id == known_reg->id) + *reg = *known_reg; + })); +} + static int check_cond_jmp_op(struct bpf_verifier_env *env, struct bpf_insn *insn, int *insn_idx) { @@ -6128,28 +10173,60 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env, dst_reg = ®s[insn->dst_reg]; is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32; - if (BPF_SRC(insn->code) == BPF_K) - pred = is_branch_taken(dst_reg, insn->imm, - opcode, is_jmp32); - else if (src_reg->type == SCALAR_VALUE && - tnum_is_const(src_reg->var_off)) - pred = is_branch_taken(dst_reg, src_reg->var_off.value, - opcode, is_jmp32); + if (BPF_SRC(insn->code) == BPF_K) { + pred = is_branch_taken(dst_reg, insn->imm, opcode, is_jmp32); + } else if (src_reg->type == SCALAR_VALUE && + is_jmp32 && tnum_is_const(tnum_subreg(src_reg->var_off))) { + pred = is_branch_taken(dst_reg, + tnum_subreg(src_reg->var_off).value, + opcode, + is_jmp32); + } else if (src_reg->type == SCALAR_VALUE && + !is_jmp32 && tnum_is_const(src_reg->var_off)) { + pred = is_branch_taken(dst_reg, + src_reg->var_off.value, + opcode, + is_jmp32); + } else if (reg_is_pkt_pointer_any(dst_reg) && + reg_is_pkt_pointer_any(src_reg) && + !is_jmp32) { + pred = is_pkt_ptr_branch_taken(dst_reg, src_reg, opcode); + } + if (pred >= 0) { - err = mark_chain_precision(env, insn->dst_reg); - if (BPF_SRC(insn->code) == BPF_X && !err) + /* If we get here with a dst_reg pointer type it is because + * above is_branch_taken() special cased the 0 comparison. + */ + if (!__is_pointer_value(false, dst_reg)) + err = mark_chain_precision(env, insn->dst_reg); + if (BPF_SRC(insn->code) == BPF_X && !err && + !__is_pointer_value(false, src_reg)) err = mark_chain_precision(env, insn->src_reg); if (err) return err; } + if (pred == 1) { - /* only follow the goto, ignore fall-through */ + /* Only follow the goto, ignore fall-through. If needed, push + * the fall-through branch for simulation under speculative + * execution. + */ + if (!env->bypass_spec_v1 && + !sanitize_speculative_path(env, insn, *insn_idx + 1, + *insn_idx)) + return -EFAULT; *insn_idx += insn->off; return 0; } else if (pred == 0) { - /* only follow fall-through branch, since - * that's where the program will go + /* Only follow the fall-through branch, since that's where the + * program will go. If needed, push the goto branch for + * simulation under speculative execution. */ + if (!env->bypass_spec_v1 && + !sanitize_speculative_path(env, insn, + *insn_idx + insn->off + 1, + *insn_idx)) + return -EFAULT; return 0; } @@ -6168,32 +10245,24 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env, */ if (BPF_SRC(insn->code) == BPF_X) { struct bpf_reg_state *src_reg = ®s[insn->src_reg]; - struct bpf_reg_state lo_reg0 = *dst_reg; - struct bpf_reg_state lo_reg1 = *src_reg; - struct bpf_reg_state *src_lo, *dst_lo; - - dst_lo = &lo_reg0; - src_lo = &lo_reg1; - coerce_reg_to_size(dst_lo, 4); - coerce_reg_to_size(src_lo, 4); if (dst_reg->type == SCALAR_VALUE && src_reg->type == SCALAR_VALUE) { if (tnum_is_const(src_reg->var_off) || - (is_jmp32 && tnum_is_const(src_lo->var_off))) + (is_jmp32 && + tnum_is_const(tnum_subreg(src_reg->var_off)))) reg_set_min_max(&other_branch_regs[insn->dst_reg], dst_reg, - is_jmp32 - ? src_lo->var_off.value - : src_reg->var_off.value, + src_reg->var_off.value, + tnum_subreg(src_reg->var_off).value, opcode, is_jmp32); else if (tnum_is_const(dst_reg->var_off) || - (is_jmp32 && tnum_is_const(dst_lo->var_off))) + (is_jmp32 && + tnum_is_const(tnum_subreg(dst_reg->var_off)))) reg_set_min_max_inv(&other_branch_regs[insn->src_reg], src_reg, - is_jmp32 - ? dst_lo->var_off.value - : dst_reg->var_off.value, + dst_reg->var_off.value, + tnum_subreg(dst_reg->var_off).value, opcode, is_jmp32); else if (!is_jmp32 && (opcode == BPF_JEQ || opcode == BPF_JNE)) @@ -6201,10 +10270,23 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env, reg_combine_min_max(&other_branch_regs[insn->src_reg], &other_branch_regs[insn->dst_reg], src_reg, dst_reg, opcode); + if (src_reg->id && + !WARN_ON_ONCE(src_reg->id != other_branch_regs[insn->src_reg].id)) { + find_equal_scalars(this_branch, src_reg); + find_equal_scalars(other_branch, &other_branch_regs[insn->src_reg]); + } + } } else if (dst_reg->type == SCALAR_VALUE) { reg_set_min_max(&other_branch_regs[insn->dst_reg], - dst_reg, insn->imm, opcode, is_jmp32); + dst_reg, insn->imm, (u32)insn->imm, + opcode, is_jmp32); + } + + if (dst_reg->type == SCALAR_VALUE && dst_reg->id && + !WARN_ON_ONCE(dst_reg->id != other_branch_regs[insn->dst_reg].id)) { + find_equal_scalars(this_branch, dst_reg); + find_equal_scalars(other_branch, &other_branch_regs[insn->dst_reg]); } /* detect if R == 0 where R is returned from bpf_map_lookup_elem(). @@ -6213,7 +10295,7 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env, */ if (!is_jmp32 && BPF_SRC(insn->code) == BPF_K && insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) && - reg_type_may_be_null(dst_reg->type)) { + type_may_be_null(dst_reg->type)) { /* Mark all identical registers in each branch as either * safe or unknown depending R == 0 or R != 0 conditional. */ @@ -6229,7 +10311,7 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env, return -EACCES; } if (env->log.level & BPF_LOG_LEVEL) - print_verifier_state(env, this_branch->frame[this_branch->curframe]); + print_insn_state(env, this_branch->frame[this_branch->curframe]); return 0; } @@ -6238,6 +10320,7 @@ static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn) { struct bpf_insn_aux_data *aux = cur_aux(env); struct bpf_reg_state *regs = cur_regs(env); + struct bpf_reg_state *dst_reg; struct bpf_map *map; int err; @@ -6254,25 +10337,69 @@ static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn) if (err) return err; + dst_reg = ®s[insn->dst_reg]; if (insn->src_reg == 0) { u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm; - regs[insn->dst_reg].type = SCALAR_VALUE; + dst_reg->type = SCALAR_VALUE; __mark_reg_known(®s[insn->dst_reg], imm); return 0; } - map = env->used_maps[aux->map_index]; + /* All special src_reg cases are listed below. From this point onwards + * we either succeed and assign a corresponding dst_reg->type after + * zeroing the offset, or fail and reject the program. + */ mark_reg_known_zero(env, regs, insn->dst_reg); - regs[insn->dst_reg].map_ptr = map; - if (insn->src_reg == BPF_PSEUDO_MAP_VALUE) { - regs[insn->dst_reg].type = PTR_TO_MAP_VALUE; - regs[insn->dst_reg].off = aux->map_off; + if (insn->src_reg == BPF_PSEUDO_BTF_ID) { + dst_reg->type = aux->btf_var.reg_type; + switch (base_type(dst_reg->type)) { + case PTR_TO_MEM: + dst_reg->mem_size = aux->btf_var.mem_size; + break; + case PTR_TO_BTF_ID: + dst_reg->btf = aux->btf_var.btf; + dst_reg->btf_id = aux->btf_var.btf_id; + break; + default: + verbose(env, "bpf verifier is misconfigured\n"); + return -EFAULT; + } + return 0; + } + + if (insn->src_reg == BPF_PSEUDO_FUNC) { + struct bpf_prog_aux *aux = env->prog->aux; + u32 subprogno = find_subprog(env, + env->insn_idx + insn->imm + 1); + + if (!aux->func_info) { + verbose(env, "missing btf func_info\n"); + return -EINVAL; + } + if (aux->func_info_aux[subprogno].linkage != BTF_FUNC_STATIC) { + verbose(env, "callback function not static\n"); + return -EINVAL; + } + + dst_reg->type = PTR_TO_FUNC; + dst_reg->subprogno = subprogno; + return 0; + } + + map = env->used_maps[aux->map_index]; + dst_reg->map_ptr = map; + + if (insn->src_reg == BPF_PSEUDO_MAP_VALUE || + insn->src_reg == BPF_PSEUDO_MAP_IDX_VALUE) { + dst_reg->type = PTR_TO_MAP_VALUE; + dst_reg->off = aux->map_off; if (map_value_has_spin_lock(map)) - regs[insn->dst_reg].id = ++env->id_gen; - } else if (insn->src_reg == BPF_PSEUDO_MAP_FD) { - regs[insn->dst_reg].type = CONST_PTR_TO_MAP; + dst_reg->id = ++env->id_gen; + } else if (insn->src_reg == BPF_PSEUDO_MAP_FD || + insn->src_reg == BPF_PSEUDO_MAP_IDX) { + dst_reg->type = CONST_PTR_TO_MAP; } else { verbose(env, "bpf verifier is misconfigured\n"); return -EINVAL; @@ -6315,7 +10442,7 @@ static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn) u8 mode = BPF_MODE(insn->code); int i, err; - if (!may_access_skb(env->prog->type)) { + if (!may_access_skb(resolve_prog_type(env->prog))) { verbose(env, "BPF_LD_[ABS|IND] instructions not allowed for this program type\n"); return -EINVAL; } @@ -6325,18 +10452,6 @@ static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn) return -EINVAL; } - if (env->subprog_cnt > 1) { - /* when program has LD_ABS insn JITs and interpreter assume - * that r1 == ctx == skb which is not the case for callees - * that can have arbitrary arguments. It's problematic - * for main prog as well since JITs would need to analyze - * all functions in order to make proper register save/restore - * decisions in the main prog. Hence disallow LD_ABS with calls - */ - verbose(env, "BPF_LD_[ABS|IND] instructions cannot be mixed with bpf-to-bpf calls\n"); - return -EINVAL; - } - if (insn->dst_reg != BPF_REG_0 || insn->off != 0 || BPF_SIZE(insn->code) == BPF_DW || (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) { @@ -6377,7 +10492,7 @@ static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn) return err; } - err = check_ctx_reg(env, ®s[ctx_reg], ctx_reg); + err = check_ptr_off_reg(env, ®s[ctx_reg], ctx_reg); if (err < 0) return err; @@ -6403,14 +10518,29 @@ static int check_return_code(struct bpf_verifier_env *env) const struct bpf_prog *prog = env->prog; struct bpf_reg_state *reg; struct tnum range = tnum_range(0, 1); + enum bpf_prog_type prog_type = resolve_prog_type(env->prog); int err; + struct bpf_func_state *frame = env->cur_state->frame[0]; + const bool is_subprog = frame->subprogno; + + /* LSM and struct_ops func-ptr's return type could be "void" */ + if (!is_subprog) { + switch (prog_type) { + case BPF_PROG_TYPE_LSM: + if (prog->expected_attach_type == BPF_LSM_CGROUP) + /* See below, can be 0 or 0-1 depending on hook. */ + break; + fallthrough; + case BPF_PROG_TYPE_STRUCT_OPS: + if (!prog->aux->attach_func_proto->type) + return 0; + break; + default: + break; + } + } - /* The struct_ops func-ptr's return type could be "void" */ - if (env->prog->type == BPF_PROG_TYPE_STRUCT_OPS && - !prog->aux->attach_func_proto->type) - return 0; - - /* eBPF calling convetion is such that R0 is used + /* eBPF calling convention is such that R0 is used * to return the value from eBPF program. * Make sure that it's readable at this time * of bpf_exit, which means that program wrote @@ -6425,11 +10555,44 @@ static int check_return_code(struct bpf_verifier_env *env) return -EACCES; } - switch (env->prog->type) { + reg = cur_regs(env) + BPF_REG_0; + + if (frame->in_async_callback_fn) { + /* enforce return zero from async callbacks like timer */ + if (reg->type != SCALAR_VALUE) { + verbose(env, "In async callback the register R0 is not a known value (%s)\n", + reg_type_str(env, reg->type)); + return -EINVAL; + } + + if (!tnum_in(tnum_const(0), reg->var_off)) { + verbose_invalid_scalar(env, reg, &range, "async callback", "R0"); + return -EINVAL; + } + return 0; + } + + if (is_subprog) { + if (reg->type != SCALAR_VALUE) { + verbose(env, "At subprogram exit the register R0 is not a scalar value (%s)\n", + reg_type_str(env, reg->type)); + return -EINVAL; + } + return 0; + } + + switch (prog_type) { case BPF_PROG_TYPE_CGROUP_SOCK_ADDR: if (env->prog->expected_attach_type == BPF_CGROUP_UDP4_RECVMSG || - env->prog->expected_attach_type == BPF_CGROUP_UDP6_RECVMSG) + env->prog->expected_attach_type == BPF_CGROUP_UDP6_RECVMSG || + env->prog->expected_attach_type == BPF_CGROUP_INET4_GETPEERNAME || + env->prog->expected_attach_type == BPF_CGROUP_INET6_GETPEERNAME || + env->prog->expected_attach_type == BPF_CGROUP_INET4_GETSOCKNAME || + env->prog->expected_attach_type == BPF_CGROUP_INET6_GETSOCKNAME) range = tnum_range(1, 1); + if (env->prog->expected_attach_type == BPF_CGROUP_INET4_BIND || + env->prog->expected_attach_type == BPF_CGROUP_INET6_BIND) + range = tnum_range(0, 3); break; case BPF_PROG_TYPE_CGROUP_SKB: if (env->prog->expected_attach_type == BPF_CGROUP_INET_EGRESS) { @@ -6448,29 +10611,60 @@ static int check_return_code(struct bpf_verifier_env *env) return 0; range = tnum_const(0); break; + case BPF_PROG_TYPE_TRACING: + switch (env->prog->expected_attach_type) { + case BPF_TRACE_FENTRY: + case BPF_TRACE_FEXIT: + range = tnum_const(0); + break; + case BPF_TRACE_RAW_TP: + case BPF_MODIFY_RETURN: + return 0; + case BPF_TRACE_ITER: + break; + default: + return -ENOTSUPP; + } + break; + case BPF_PROG_TYPE_SK_LOOKUP: + range = tnum_range(SK_DROP, SK_PASS); + break; + + case BPF_PROG_TYPE_LSM: + if (env->prog->expected_attach_type != BPF_LSM_CGROUP) { + /* Regular BPF_PROG_TYPE_LSM programs can return + * any value. + */ + return 0; + } + if (!env->prog->aux->attach_func_proto->type) { + /* Make sure programs that attach to void + * hooks don't try to modify return value. + */ + range = tnum_range(1, 1); + } + break; + + case BPF_PROG_TYPE_EXT: + /* freplace program can return anything as its return value + * depends on the to-be-replaced kernel func or bpf program. + */ default: return 0; } - reg = cur_regs(env) + BPF_REG_0; if (reg->type != SCALAR_VALUE) { verbose(env, "At program exit the register R0 is not a known value (%s)\n", - reg_type_str[reg->type]); + reg_type_str(env, reg->type)); return -EINVAL; } if (!tnum_in(range, reg->var_off)) { - char tn_buf[48]; - - verbose(env, "At program exit the register R0 "); - if (!tnum_is_unknown(reg->var_off)) { - tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); - verbose(env, "has value %s", tn_buf); - } else { - verbose(env, "has unknown scalar value"); - } - tnum_strn(tn_buf, sizeof(tn_buf), range); - verbose(env, " should have been in %s\n", tn_buf); + verbose_invalid_scalar(env, reg, &range, "program exit", "R0"); + if (prog->expected_attach_type == BPF_LSM_CGROUP && + prog_type == BPF_PROG_TYPE_LSM && + !prog->aux->attach_func_proto->type) + verbose(env, "Note, BPF_LSM_CGROUP that attach to void LSM hooks can't modify return value!\n"); return -EINVAL; } @@ -6540,6 +10734,11 @@ static void init_explored_state(struct bpf_verifier_env *env, int idx) env->insn_aux_data[idx].prune_point = true; } +enum { + DONE_EXPLORING = 0, + KEEP_EXPLORING = 1, +}; + /* t, w, e - match pseudo-code above: * t - index of current instruction * w - next instruction @@ -6552,10 +10751,10 @@ static int push_insn(int t, int w, int e, struct bpf_verifier_env *env, int *insn_state = env->cfg.insn_state; if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH)) - return 0; + return DONE_EXPLORING; if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH)) - return 0; + return DONE_EXPLORING; if (w < 0 || w >= env->prog->len) { verbose_linfo(env, t, "%d: ", t); @@ -6574,10 +10773,10 @@ static int push_insn(int t, int w, int e, struct bpf_verifier_env *env, if (env->cfg.cur_stack >= env->prog->len) return -E2BIG; insn_stack[env->cfg.cur_stack++] = w; - return 1; + return KEEP_EXPLORING; } else if ((insn_state[w] & 0xF0) == DISCOVERED) { - if (loop_ok && env->allow_ptr_leaks) - return 0; + if (loop_ok && env->bpf_capable) + return DONE_EXPLORING; verbose_linfo(env, t, "%d: ", t); verbose_linfo(env, w, "%d: ", w); verbose(env, "back-edge from insn %d to %d\n", t, w); @@ -6589,7 +10788,99 @@ static int push_insn(int t, int w, int e, struct bpf_verifier_env *env, verbose(env, "insn state internal bug\n"); return -EFAULT; } - return 0; + return DONE_EXPLORING; +} + +static int visit_func_call_insn(int t, int insn_cnt, + struct bpf_insn *insns, + struct bpf_verifier_env *env, + bool visit_callee) +{ + int ret; + + ret = push_insn(t, t + 1, FALLTHROUGH, env, false); + if (ret) + return ret; + + if (t + 1 < insn_cnt) + init_explored_state(env, t + 1); + if (visit_callee) { + init_explored_state(env, t); + ret = push_insn(t, t + insns[t].imm + 1, BRANCH, env, + /* It's ok to allow recursion from CFG point of + * view. __check_func_call() will do the actual + * check. + */ + bpf_pseudo_func(insns + t)); + } + return ret; +} + +/* Visits the instruction at index t and returns one of the following: + * < 0 - an error occurred + * DONE_EXPLORING - the instruction was fully explored + * KEEP_EXPLORING - there is still work to be done before it is fully explored + */ +static int visit_insn(int t, int insn_cnt, struct bpf_verifier_env *env) +{ + struct bpf_insn *insns = env->prog->insnsi; + int ret; + + if (bpf_pseudo_func(insns + t)) + return visit_func_call_insn(t, insn_cnt, insns, env, true); + + /* All non-branch instructions have a single fall-through edge. */ + if (BPF_CLASS(insns[t].code) != BPF_JMP && + BPF_CLASS(insns[t].code) != BPF_JMP32) + return push_insn(t, t + 1, FALLTHROUGH, env, false); + + switch (BPF_OP(insns[t].code)) { + case BPF_EXIT: + return DONE_EXPLORING; + + case BPF_CALL: + if (insns[t].imm == BPF_FUNC_timer_set_callback) + /* Mark this call insn to trigger is_state_visited() check + * before call itself is processed by __check_func_call(). + * Otherwise new async state will be pushed for further + * exploration. + */ + init_explored_state(env, t); + return visit_func_call_insn(t, insn_cnt, insns, env, + insns[t].src_reg == BPF_PSEUDO_CALL); + + case BPF_JA: + if (BPF_SRC(insns[t].code) != BPF_K) + return -EINVAL; + + /* unconditional jump with single edge */ + ret = push_insn(t, t + insns[t].off + 1, FALLTHROUGH, env, + true); + if (ret) + return ret; + + /* unconditional jmp is not a good pruning point, + * but it's marked, since backtracking needs + * to record jmp history in is_state_visited(). + */ + init_explored_state(env, t + insns[t].off + 1); + /* tell verifier to check for equivalent states + * after every call and jump + */ + if (t + 1 < insn_cnt) + init_explored_state(env, t + 1); + + return ret; + + default: + /* conditional jump with two edges */ + init_explored_state(env, t); + ret = push_insn(t, t + 1, FALLTHROUGH, env, true); + if (ret) + return ret; + + return push_insn(t, t + insns[t].off + 1, BRANCH, env, true); + } } /* non-recursive depth-first-search to detect loops in BPF program @@ -6597,11 +10888,10 @@ static int push_insn(int t, int w, int e, struct bpf_verifier_env *env, */ static int check_cfg(struct bpf_verifier_env *env) { - struct bpf_insn *insns = env->prog->insnsi; int insn_cnt = env->prog->len; int *insn_stack, *insn_state; int ret = 0; - int i, t; + int i; insn_state = env->cfg.insn_state = kvcalloc(insn_cnt, sizeof(int), GFP_KERNEL); if (!insn_state) @@ -6617,92 +10907,32 @@ static int check_cfg(struct bpf_verifier_env *env) insn_stack[0] = 0; /* 0 is the first instruction */ env->cfg.cur_stack = 1; -peek_stack: - if (env->cfg.cur_stack == 0) - goto check_state; - t = insn_stack[env->cfg.cur_stack - 1]; - - if (BPF_CLASS(insns[t].code) == BPF_JMP || - BPF_CLASS(insns[t].code) == BPF_JMP32) { - u8 opcode = BPF_OP(insns[t].code); - - if (opcode == BPF_EXIT) { - goto mark_explored; - } else if (opcode == BPF_CALL) { - ret = push_insn(t, t + 1, FALLTHROUGH, env, false); - if (ret == 1) - goto peek_stack; - else if (ret < 0) - goto err_free; - if (t + 1 < insn_cnt) - init_explored_state(env, t + 1); - if (insns[t].src_reg == BPF_PSEUDO_CALL) { - init_explored_state(env, t); - ret = push_insn(t, t + insns[t].imm + 1, BRANCH, - env, false); - if (ret == 1) - goto peek_stack; - else if (ret < 0) - goto err_free; - } - } else if (opcode == BPF_JA) { - if (BPF_SRC(insns[t].code) != BPF_K) { - ret = -EINVAL; - goto err_free; - } - /* unconditional jump with single edge */ - ret = push_insn(t, t + insns[t].off + 1, - FALLTHROUGH, env, true); - if (ret == 1) - goto peek_stack; - else if (ret < 0) - goto err_free; - /* unconditional jmp is not a good pruning point, - * but it's marked, since backtracking needs - * to record jmp history in is_state_visited(). - */ - init_explored_state(env, t + insns[t].off + 1); - /* tell verifier to check for equivalent states - * after every call and jump - */ - if (t + 1 < insn_cnt) - init_explored_state(env, t + 1); - } else { - /* conditional jump with two edges */ - init_explored_state(env, t); - ret = push_insn(t, t + 1, FALLTHROUGH, env, true); - if (ret == 1) - goto peek_stack; - else if (ret < 0) - goto err_free; + while (env->cfg.cur_stack > 0) { + int t = insn_stack[env->cfg.cur_stack - 1]; - ret = push_insn(t, t + insns[t].off + 1, BRANCH, env, true); - if (ret == 1) - goto peek_stack; - else if (ret < 0) - goto err_free; - } - } else { - /* all other non-branch instructions with single - * fall-through edge - */ - ret = push_insn(t, t + 1, FALLTHROUGH, env, false); - if (ret == 1) - goto peek_stack; - else if (ret < 0) + ret = visit_insn(t, insn_cnt, env); + switch (ret) { + case DONE_EXPLORING: + insn_state[t] = EXPLORED; + env->cfg.cur_stack--; + break; + case KEEP_EXPLORING: + break; + default: + if (ret > 0) { + verbose(env, "visit_insn internal bug\n"); + ret = -EFAULT; + } goto err_free; + } } -mark_explored: - insn_state[t] = EXPLORED; - if (env->cfg.cur_stack-- <= 0) { + if (env->cfg.cur_stack < 0) { verbose(env, "pop stack internal bug\n"); ret = -EFAULT; goto err_free; } - goto peek_stack; -check_state: for (i = 0; i < insn_cnt; i++) { if (insn_state[i] != EXPLORED) { verbose(env, "unreachable insn %d\n", i); @@ -6719,28 +10949,49 @@ err_free: return ret; } +static int check_abnormal_return(struct bpf_verifier_env *env) +{ + int i; + + for (i = 1; i < env->subprog_cnt; i++) { + if (env->subprog_info[i].has_ld_abs) { + verbose(env, "LD_ABS is not allowed in subprogs without BTF\n"); + return -EINVAL; + } + if (env->subprog_info[i].has_tail_call) { + verbose(env, "tail_call is not allowed in subprogs without BTF\n"); + return -EINVAL; + } + } + return 0; +} + /* The minimum supported BTF func info size */ #define MIN_BPF_FUNCINFO_SIZE 8 #define MAX_FUNCINFO_REC_SIZE 252 static int check_btf_func(struct bpf_verifier_env *env, const union bpf_attr *attr, - union bpf_attr __user *uattr) + bpfptr_t uattr) { + const struct btf_type *type, *func_proto, *ret_type; u32 i, nfuncs, urec_size, min_size; u32 krec_size = sizeof(struct bpf_func_info); struct bpf_func_info *krecord; struct bpf_func_info_aux *info_aux = NULL; - const struct btf_type *type; struct bpf_prog *prog; const struct btf *btf; - void __user *urecord; + bpfptr_t urecord; u32 prev_offset = 0; - int ret = 0; + bool scalar_return; + int ret = -ENOMEM; nfuncs = attr->func_info_cnt; - if (!nfuncs) + if (!nfuncs) { + if (check_abnormal_return(env)) + return -EINVAL; return 0; + } if (nfuncs != env->subprog_cnt) { verbose(env, "number of funcs in func_info doesn't match number of subprogs\n"); @@ -6758,7 +11009,7 @@ static int check_btf_func(struct bpf_verifier_env *env, prog = env->prog; btf = prog->aux->btf; - urecord = u64_to_user_ptr(attr->func_info); + urecord = make_bpfptr(attr->func_info, uattr.is_kernel); min_size = min_t(u32, krec_size, urec_size); krecord = kvcalloc(nfuncs, krec_size, GFP_KERNEL | __GFP_NOWARN); @@ -6776,37 +11027,37 @@ static int check_btf_func(struct bpf_verifier_env *env, /* set the size kernel expects so loader can zero * out the rest of the record. */ - if (put_user(min_size, &uattr->func_info_rec_size)) + if (copy_to_bpfptr_offset(uattr, + offsetof(union bpf_attr, func_info_rec_size), + &min_size, sizeof(min_size))) ret = -EFAULT; } goto err_free; } - if (copy_from_user(&krecord[i], urecord, min_size)) { + if (copy_from_bpfptr(&krecord[i], urecord, min_size)) { ret = -EFAULT; goto err_free; } /* check insn_off */ + ret = -EINVAL; if (i == 0) { if (krecord[i].insn_off) { verbose(env, "nonzero insn_off %u for the first func info record", krecord[i].insn_off); - ret = -EINVAL; goto err_free; } } else if (krecord[i].insn_off <= prev_offset) { verbose(env, "same or smaller insn offset (%u) than previous func info record (%u)", krecord[i].insn_off, prev_offset); - ret = -EINVAL; goto err_free; } if (env->subprog_info[i].start != krecord[i].insn_off) { verbose(env, "func_info BTF section doesn't match subprog layout in BPF program\n"); - ret = -EINVAL; goto err_free; } @@ -6815,12 +11066,28 @@ static int check_btf_func(struct bpf_verifier_env *env, if (!type || !btf_type_is_func(type)) { verbose(env, "invalid type id %d in func info", krecord[i].type_id); - ret = -EINVAL; goto err_free; } info_aux[i].linkage = BTF_INFO_VLEN(type->info); + + func_proto = btf_type_by_id(btf, type->type); + if (unlikely(!func_proto || !btf_type_is_func_proto(func_proto))) + /* btf_func_check() already verified it during BTF load */ + goto err_free; + ret_type = btf_type_skip_modifiers(btf, func_proto->type, NULL); + scalar_return = + btf_type_is_small_int(ret_type) || btf_is_any_enum(ret_type); + if (i && !scalar_return && env->subprog_info[i].has_ld_abs) { + verbose(env, "LD_ABS is only allowed in functions that return 'int'.\n"); + goto err_free; + } + if (i && !scalar_return && env->subprog_info[i].has_tail_call) { + verbose(env, "tail_call is only allowed in functions that return 'int'.\n"); + goto err_free; + } + prev_offset = krecord[i].insn_off; - urecord += urec_size; + bpfptr_add(&urecord, urec_size); } prog->aux->func_info = krecord; @@ -6846,25 +11113,26 @@ static void adjust_btf_func(struct bpf_verifier_env *env) aux->func_info[i].insn_off = env->subprog_info[i].start; } -#define MIN_BPF_LINEINFO_SIZE (offsetof(struct bpf_line_info, line_col) + \ - sizeof(((struct bpf_line_info *)(0))->line_col)) +#define MIN_BPF_LINEINFO_SIZE offsetofend(struct bpf_line_info, line_col) #define MAX_LINEINFO_REC_SIZE MAX_FUNCINFO_REC_SIZE static int check_btf_line(struct bpf_verifier_env *env, const union bpf_attr *attr, - union bpf_attr __user *uattr) + bpfptr_t uattr) { u32 i, s, nr_linfo, ncopy, expected_size, rec_size, prev_offset = 0; struct bpf_subprog_info *sub; struct bpf_line_info *linfo; struct bpf_prog *prog; const struct btf *btf; - void __user *ulinfo; + bpfptr_t ulinfo; int err; nr_linfo = attr->line_info_cnt; if (!nr_linfo) return 0; + if (nr_linfo > INT_MAX / sizeof(struct bpf_line_info)) + return -EINVAL; rec_size = attr->line_info_rec_size; if (rec_size < MIN_BPF_LINEINFO_SIZE || @@ -6885,7 +11153,7 @@ static int check_btf_line(struct bpf_verifier_env *env, s = 0; sub = env->subprog_info; - ulinfo = u64_to_user_ptr(attr->line_info); + ulinfo = make_bpfptr(attr->line_info, uattr.is_kernel); expected_size = sizeof(struct bpf_line_info); ncopy = min_t(u32, expected_size, rec_size); for (i = 0; i < nr_linfo; i++) { @@ -6893,14 +11161,15 @@ static int check_btf_line(struct bpf_verifier_env *env, if (err) { if (err == -E2BIG) { verbose(env, "nonzero tailing record in line_info"); - if (put_user(expected_size, - &uattr->line_info_rec_size)) + if (copy_to_bpfptr_offset(uattr, + offsetof(union bpf_attr, line_info_rec_size), + &expected_size, sizeof(expected_size))) err = -EFAULT; } goto err_free; } - if (copy_from_user(&linfo[i], ulinfo, ncopy)) { + if (copy_from_bpfptr(&linfo[i], ulinfo, ncopy)) { err = -EFAULT; goto err_free; } @@ -6952,7 +11221,7 @@ static int check_btf_line(struct bpf_verifier_env *env, } prev_offset = linfo[i].insn_off; - ulinfo += rec_size; + bpfptr_add(&ulinfo, rec_size); } if (s != env->subprog_cnt) { @@ -6972,19 +11241,98 @@ err_free: return err; } +#define MIN_CORE_RELO_SIZE sizeof(struct bpf_core_relo) +#define MAX_CORE_RELO_SIZE MAX_FUNCINFO_REC_SIZE + +static int check_core_relo(struct bpf_verifier_env *env, + const union bpf_attr *attr, + bpfptr_t uattr) +{ + u32 i, nr_core_relo, ncopy, expected_size, rec_size; + struct bpf_core_relo core_relo = {}; + struct bpf_prog *prog = env->prog; + const struct btf *btf = prog->aux->btf; + struct bpf_core_ctx ctx = { + .log = &env->log, + .btf = btf, + }; + bpfptr_t u_core_relo; + int err; + + nr_core_relo = attr->core_relo_cnt; + if (!nr_core_relo) + return 0; + if (nr_core_relo > INT_MAX / sizeof(struct bpf_core_relo)) + return -EINVAL; + + rec_size = attr->core_relo_rec_size; + if (rec_size < MIN_CORE_RELO_SIZE || + rec_size > MAX_CORE_RELO_SIZE || + rec_size % sizeof(u32)) + return -EINVAL; + + u_core_relo = make_bpfptr(attr->core_relos, uattr.is_kernel); + expected_size = sizeof(struct bpf_core_relo); + ncopy = min_t(u32, expected_size, rec_size); + + /* Unlike func_info and line_info, copy and apply each CO-RE + * relocation record one at a time. + */ + for (i = 0; i < nr_core_relo; i++) { + /* future proofing when sizeof(bpf_core_relo) changes */ + err = bpf_check_uarg_tail_zero(u_core_relo, expected_size, rec_size); + if (err) { + if (err == -E2BIG) { + verbose(env, "nonzero tailing record in core_relo"); + if (copy_to_bpfptr_offset(uattr, + offsetof(union bpf_attr, core_relo_rec_size), + &expected_size, sizeof(expected_size))) + err = -EFAULT; + } + break; + } + + if (copy_from_bpfptr(&core_relo, u_core_relo, ncopy)) { + err = -EFAULT; + break; + } + + if (core_relo.insn_off % 8 || core_relo.insn_off / 8 >= prog->len) { + verbose(env, "Invalid core_relo[%u].insn_off:%u prog->len:%u\n", + i, core_relo.insn_off, prog->len); + err = -EINVAL; + break; + } + + err = bpf_core_apply(&ctx, &core_relo, i, + &prog->insnsi[core_relo.insn_off / 8]); + if (err) + break; + bpfptr_add(&u_core_relo, rec_size); + } + return err; +} + static int check_btf_info(struct bpf_verifier_env *env, const union bpf_attr *attr, - union bpf_attr __user *uattr) + bpfptr_t uattr) { struct btf *btf; int err; - if (!attr->func_info_cnt && !attr->line_info_cnt) + if (!attr->func_info_cnt && !attr->line_info_cnt) { + if (check_abnormal_return(env)) + return -EINVAL; return 0; + } btf = btf_get_by_fd(attr->prog_btf_fd); if (IS_ERR(btf)) return PTR_ERR(btf); + if (btf_is_kernel(btf)) { + btf_put(btf); + return -EACCES; + } env->prog->aux->btf = btf; err = check_btf_func(env, attr, uattr); @@ -6995,6 +11343,10 @@ static int check_btf_info(struct bpf_verifier_env *env, if (err) return err; + err = check_core_relo(env, attr, uattr); + if (err) + return err; + return 0; } @@ -7005,16 +11357,13 @@ static bool range_within(struct bpf_reg_state *old, return old->umin_value <= cur->umin_value && old->umax_value >= cur->umax_value && old->smin_value <= cur->smin_value && - old->smax_value >= cur->smax_value; + old->smax_value >= cur->smax_value && + old->u32_min_value <= cur->u32_min_value && + old->u32_max_value >= cur->u32_max_value && + old->s32_min_value <= cur->s32_min_value && + old->s32_max_value >= cur->s32_max_value; } -/* Maximum number of register states that can exist at once */ -#define ID_MAP_SIZE (MAX_BPF_REG + MAX_BPF_STACK / BPF_REG_SIZE) -struct idpair { - u32 old; - u32 cur; -}; - /* If in the old state two registers had the same id, then they need to have * the same id in the new state as well. But that id could be different from * the old state, so we need to track the mapping from old to new ids. @@ -7025,11 +11374,11 @@ struct idpair { * So we look through our idmap to see if this old id has been seen before. If * so, we require the new id to match; otherwise, we add the id pair to the map. */ -static bool check_ids(u32 old_id, u32 cur_id, struct idpair *idmap) +static bool check_ids(u32 old_id, u32 cur_id, struct bpf_id_pair *idmap) { unsigned int i; - for (i = 0; i < ID_MAP_SIZE; i++) { + for (i = 0; i < BPF_ID_MAP_SIZE; i++) { if (!idmap[i].old) { /* Reached an empty slot; haven't seen this id before */ idmap[i].old = old_id; @@ -7106,7 +11455,7 @@ static void clean_verifier_state(struct bpf_verifier_env *env, * Since the verifier pushes the branch states as it sees them while exploring * the program the condition of walking the branch instruction for the second * time means that all states below this branch were already explored and - * their final liveness markes are already propagated. + * their final liveness marks are already propagated. * Hence when the verifier completes the search of state list in is_state_visited() * we can call this clean_live_states() function to mark all liveness states * as REG_LIVE_DONE to indicate that 'parent' pointers of 'struct bpf_reg_state' @@ -7141,8 +11490,8 @@ next: } /* Returns true if (rold safe implies rcur safe) */ -static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur, - struct idpair *idmap) +static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold, + struct bpf_reg_state *rcur, struct bpf_id_pair *idmap) { bool equal; @@ -7166,8 +11515,10 @@ static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur, return true; if (rcur->type == NOT_INIT) return false; - switch (rold->type) { + switch (base_type(rold->type)) { case SCALAR_VALUE: + if (env->explore_alu_limits) + return false; if (rcur->type == SCALAR_VALUE) { if (!rold->precise && !rcur->precise) return true; @@ -7184,7 +11535,24 @@ static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur, */ return false; } + case PTR_TO_MAP_KEY: case PTR_TO_MAP_VALUE: + /* a PTR_TO_MAP_VALUE could be safe to use as a + * PTR_TO_MAP_VALUE_OR_NULL into the same map. + * However, if the old PTR_TO_MAP_VALUE_OR_NULL then got NULL- + * checked, doing so could have affected others with the same + * id, and we can't check for that because we lost the id when + * we converted to a PTR_TO_MAP_VALUE. + */ + if (type_may_be_null(rold->type)) { + if (!type_may_be_null(rcur->type)) + return false; + if (memcmp(rold, rcur, offsetof(struct bpf_reg_state, id))) + return false; + /* Check our ids match any regs they're supposed to */ + return check_ids(rold->id, rcur->id, idmap); + } + /* If the new min/max/var_off satisfy the old ones and * everything else matches, we are OK. * 'id' is not compared, since it's only used for maps with @@ -7196,20 +11564,6 @@ static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur, return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 && range_within(rold, rcur) && tnum_in(rold->var_off, rcur->var_off); - case PTR_TO_MAP_VALUE_OR_NULL: - /* a PTR_TO_MAP_VALUE could be safe to use as a - * PTR_TO_MAP_VALUE_OR_NULL into the same map. - * However, if the old PTR_TO_MAP_VALUE_OR_NULL then got NULL- - * checked, doing so could have affected others with the same - * id, and we can't check for that because we lost the id when - * we converted to a PTR_TO_MAP_VALUE. - */ - if (rcur->type != PTR_TO_MAP_VALUE_OR_NULL) - return false; - if (memcmp(rold, rcur, offsetof(struct bpf_reg_state, id))) - return false; - /* Check our ids match any regs they're supposed to */ - return check_ids(rold->id, rcur->id, idmap); case PTR_TO_PACKET_META: case PTR_TO_PACKET: if (rcur->type != rold->type) @@ -7238,11 +11592,8 @@ static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur, case PTR_TO_PACKET_END: case PTR_TO_FLOW_KEYS: case PTR_TO_SOCKET: - case PTR_TO_SOCKET_OR_NULL: case PTR_TO_SOCK_COMMON: - case PTR_TO_SOCK_COMMON_OR_NULL: case PTR_TO_TCP_SOCK: - case PTR_TO_TCP_SOCK_OR_NULL: case PTR_TO_XDP_SOCK: /* Only valid matches are exact, which memcmp() above * would have accepted @@ -7257,9 +11608,8 @@ static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur, return false; } -static bool stacksafe(struct bpf_func_state *old, - struct bpf_func_state *cur, - struct idpair *idmap) +static bool stacksafe(struct bpf_verifier_env *env, struct bpf_func_state *old, + struct bpf_func_state *cur, struct bpf_id_pair *idmap) { int i, spi; @@ -7295,18 +11645,17 @@ static bool stacksafe(struct bpf_func_state *old, if (old->stack[spi].slot_type[i % BPF_REG_SIZE] != cur->stack[spi].slot_type[i % BPF_REG_SIZE]) /* Ex: old explored (safe) state has STACK_SPILL in - * this stack slot, but current has has STACK_MISC -> + * this stack slot, but current has STACK_MISC -> * this verifier states are not equivalent, * return false to continue verification of this path */ return false; - if (i % BPF_REG_SIZE) + if (i % BPF_REG_SIZE != BPF_REG_SIZE - 1) continue; - if (old->stack[spi].slot_type[0] != STACK_SPILL) + if (!is_spilled_reg(&old->stack[spi])) continue; - if (!regsafe(&old->stack[spi].spilled_ptr, - &cur->stack[spi].spilled_ptr, - idmap)) + if (!regsafe(env, &old->stack[spi].spilled_ptr, + &cur->stack[spi].spilled_ptr, idmap)) /* when explored and current stack slot are both storing * spilled registers, check that stored pointers types * are the same as well. @@ -7356,32 +11705,24 @@ static bool refsafe(struct bpf_func_state *old, struct bpf_func_state *cur) * whereas register type in current state is meaningful, it means that * the current state will reach 'bpf_exit' instruction safely */ -static bool func_states_equal(struct bpf_func_state *old, +static bool func_states_equal(struct bpf_verifier_env *env, struct bpf_func_state *old, struct bpf_func_state *cur) { - struct idpair *idmap; - bool ret = false; int i; - idmap = kcalloc(ID_MAP_SIZE, sizeof(struct idpair), GFP_KERNEL); - /* If we failed to allocate the idmap, just say it's not safe */ - if (!idmap) - return false; - - for (i = 0; i < MAX_BPF_REG; i++) { - if (!regsafe(&old->regs[i], &cur->regs[i], idmap)) - goto out_free; - } + memset(env->idmap_scratch, 0, sizeof(env->idmap_scratch)); + for (i = 0; i < MAX_BPF_REG; i++) + if (!regsafe(env, &old->regs[i], &cur->regs[i], + env->idmap_scratch)) + return false; - if (!stacksafe(old, cur, idmap)) - goto out_free; + if (!stacksafe(env, old, cur, env->idmap_scratch)) + return false; if (!refsafe(old, cur)) - goto out_free; - ret = true; -out_free: - kfree(idmap); - return ret; + return false; + + return true; } static bool states_equal(struct bpf_verifier_env *env, @@ -7408,7 +11749,7 @@ static bool states_equal(struct bpf_verifier_env *env, for (i = 0; i <= old->curframe; i++) { if (old->frame[i]->callsite != cur->frame[i]->callsite) return false; - if (!func_states_equal(old->frame[i], cur->frame[i])) + if (!func_states_equal(env, old->frame[i], cur->frame[i])) return false; } return true; @@ -7518,7 +11859,7 @@ static int propagate_precision(struct bpf_verifier_env *env, } for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) { - if (state->stack[i].slot_type[0] != STACK_SPILL) + if (!is_spilled_reg(&state->stack[i])) continue; state_reg = &state->stack[i].spilled_ptr; if (state_reg->type != SCALAR_VALUE || @@ -7589,9 +11930,25 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx) states_cnt++; if (sl->state.insn_idx != insn_idx) goto next; + if (sl->state.branches) { - if (states_maybe_looping(&sl->state, cur) && - states_equal(env, &sl->state, cur)) { + struct bpf_func_state *frame = sl->state.frame[sl->state.curframe]; + + if (frame->in_async_callback_fn && + frame->async_entry_cnt != cur->frame[cur->curframe]->async_entry_cnt) { + /* Different async_entry_cnt means that the verifier is + * processing another entry into async callback. + * Seeing the same state is not an indication of infinite + * loop or infinite recursion. + * But finding the same state doesn't mean that it's safe + * to stop processing the current state. The previous state + * hasn't yet reached bpf_exit, since state.branches > 0. + * Checking in_async_callback_fn alone is not enough either. + * Since the verifier still needs to catch infinite loops + * inside async callbacks. + */ + } else if (states_maybe_looping(&sl->state, cur) && + states_equal(env, &sl->state, cur)) { verbose_linfo(env, insn_idx, "; "); verbose(env, "infinite loop detected at insn %d\n", insn_idx); return -EINVAL; @@ -7685,7 +12042,7 @@ next: if (env->max_states_per_insn < states_cnt) env->max_states_per_insn = states_cnt; - if (!env->allow_ptr_leaks && states_cnt > BPF_COMPLEXITY_LIMIT_STATES) + if (!env->bpf_capable && states_cnt > BPF_COMPLEXITY_LIMIT_STATES) return push_jmp_history(env, cur); if (!add_new_state) @@ -7762,14 +12119,11 @@ next: /* Return true if it's OK to have the same insn return a different type. */ static bool reg_type_mismatch_ok(enum bpf_reg_type type) { - switch (type) { + switch (base_type(type)) { case PTR_TO_CTX: case PTR_TO_SOCKET: - case PTR_TO_SOCKET_OR_NULL: case PTR_TO_SOCK_COMMON: - case PTR_TO_SOCK_COMMON_OR_NULL: case PTR_TO_TCP_SOCK: - case PTR_TO_TCP_SOCK_OR_NULL: case PTR_TO_XDP_SOCK: case PTR_TO_BTF_ID: return false; @@ -7798,6 +12152,7 @@ static bool reg_type_mismatch(enum bpf_reg_type src, enum bpf_reg_type prev) static int do_check(struct bpf_verifier_env *env) { + bool pop_log = !(env->log.level & BPF_LOG_LEVEL2); struct bpf_verifier_state *state = env->cur_state; struct bpf_insn *insns = env->prog->insnsi; struct bpf_reg_state *regs; @@ -7850,28 +12205,31 @@ static int do_check(struct bpf_verifier_env *env) if (need_resched()) cond_resched(); - if (env->log.level & BPF_LOG_LEVEL2 || - (env->log.level & BPF_LOG_LEVEL && do_print_state)) { - if (env->log.level & BPF_LOG_LEVEL2) - verbose(env, "%d:", env->insn_idx); - else - verbose(env, "\nfrom %d to %d%s:", - env->prev_insn_idx, env->insn_idx, - env->cur_state->speculative ? - " (speculative execution)" : ""); - print_verifier_state(env, state->frame[state->curframe]); + if (env->log.level & BPF_LOG_LEVEL2 && do_print_state) { + verbose(env, "\nfrom %d to %d%s:", + env->prev_insn_idx, env->insn_idx, + env->cur_state->speculative ? + " (speculative execution)" : ""); + print_verifier_state(env, state->frame[state->curframe], true); do_print_state = false; } if (env->log.level & BPF_LOG_LEVEL) { const struct bpf_insn_cbs cbs = { + .cb_call = disasm_kfunc_name, .cb_print = verbose, .private_data = env, }; + if (verifier_state_scratched(env)) + print_insn_state(env, state->frame[state->curframe]); + verbose_linfo(env, env->insn_idx, "; "); + env->prev_log_len = env->log.len_used; verbose(env, "%d: ", env->insn_idx); print_bpf_insn(&cbs, insn, env->allow_ptr_leaks); + env->prev_insn_print_len = env->log.len_used - env->prev_log_len; + env->prev_log_len = env->log.len_used; } if (bpf_prog_is_dev_bound(env->prog->aux)) { @@ -7882,7 +12240,7 @@ static int do_check(struct bpf_verifier_env *env) } regs = cur_regs(env); - env->insn_aux_data[env->insn_idx].seen = env->pass_cnt; + sanitize_mark_insn_seen(env); prev_insn_idx = env->insn_idx; if (class == BPF_ALU || class == BPF_ALU64) { @@ -7939,14 +12297,19 @@ static int do_check(struct bpf_verifier_env *env) } else if (class == BPF_STX) { enum bpf_reg_type *prev_dst_type, dst_reg_type; - if (BPF_MODE(insn->code) == BPF_XADD) { - err = check_xadd(env, env->insn_idx, insn); + if (BPF_MODE(insn->code) == BPF_ATOMIC) { + err = check_atomic(env, env->insn_idx, insn); if (err) return err; env->insn_idx++; continue; } + if (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0) { + verbose(env, "BPF_STX uses reserved fields\n"); + return -EINVAL; + } + /* check src1 operand */ err = check_reg_arg(env, insn->src_reg, SRC_OP); if (err) @@ -7988,7 +12351,7 @@ static int do_check(struct bpf_verifier_env *env) if (is_ctx_reg(env, insn->dst_reg)) { verbose(env, "BPF_ST stores into R%d %s is not allowed\n", insn->dst_reg, - reg_type_str[reg_state(env, insn->dst_reg)->type]); + reg_type_str(env, reg_state(env, insn->dst_reg)->type)); return -EACCES; } @@ -8005,9 +12368,11 @@ static int do_check(struct bpf_verifier_env *env) env->jmps_processed++; if (opcode == BPF_CALL) { if (BPF_SRC(insn->code) != BPF_K || - insn->off != 0 || + (insn->src_reg != BPF_PSEUDO_KFUNC_CALL + && insn->off != 0) || (insn->src_reg != BPF_REG_0 && - insn->src_reg != BPF_PSEUDO_CALL) || + insn->src_reg != BPF_PSEUDO_CALL && + insn->src_reg != BPF_PSEUDO_KFUNC_CALL) || insn->dst_reg != BPF_REG_0 || class == BPF_JMP32) { verbose(env, "BPF_CALL uses reserved fields\n"); @@ -8022,11 +12387,12 @@ static int do_check(struct bpf_verifier_env *env) } if (insn->src_reg == BPF_PSEUDO_CALL) err = check_func_call(env, insn, &env->insn_idx); + else if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) + err = check_kfunc_call(env, insn, &env->insn_idx); else - err = check_helper_call(env, insn->imm, env->insn_idx); + err = check_helper_call(env, insn, &env->insn_idx); if (err) return err; - } else if (opcode == BPF_JA) { if (BPF_SRC(insn->code) != BPF_K || insn->imm != 0 || @@ -8055,6 +12421,16 @@ static int do_check(struct bpf_verifier_env *env) return -EINVAL; } + /* We must do check_reference_leak here before + * prepare_func_exit to handle the case when + * state->curframe > 0, it may be a callback + * function, for which reference_state must + * match caller reference state when it exits. + */ + err = check_reference_leak(env); + if (err) + return err; + if (state->curframe) { /* exit from nested function */ err = prepare_func_exit(env, &env->insn_idx); @@ -8064,17 +12440,14 @@ static int do_check(struct bpf_verifier_env *env) continue; } - err = check_reference_leak(env); - if (err) - return err; - err = check_return_code(env); if (err) return err; process_bpf_exit: + mark_verifier_state_scratched(env); update_branch_counts(env, env->cur_state); err = pop_stack(env, &prev_insn_idx, - &env->insn_idx); + &env->insn_idx, pop_log); if (err < 0) { if (err != -ENOENT) return err; @@ -8102,7 +12475,7 @@ process_bpf_exit: return err; env->insn_idx++; - env->insn_aux_data[env->insn_idx].seen = env->pass_cnt; + sanitize_mark_insn_seen(env); } else { verbose(env, "invalid BPF_LD mode\n"); return -EINVAL; @@ -8118,12 +12491,165 @@ process_bpf_exit: return 0; } -static int check_map_prealloc(struct bpf_map *map) +static int find_btf_percpu_datasec(struct btf *btf) +{ + const struct btf_type *t; + const char *tname; + int i, n; + + /* + * Both vmlinux and module each have their own ".data..percpu" + * DATASECs in BTF. So for module's case, we need to skip vmlinux BTF + * types to look at only module's own BTF types. + */ + n = btf_nr_types(btf); + if (btf_is_module(btf)) + i = btf_nr_types(btf_vmlinux); + else + i = 1; + + for(; i < n; i++) { + t = btf_type_by_id(btf, i); + if (BTF_INFO_KIND(t->info) != BTF_KIND_DATASEC) + continue; + + tname = btf_name_by_offset(btf, t->name_off); + if (!strcmp(tname, ".data..percpu")) + return i; + } + + return -ENOENT; +} + +/* replace pseudo btf_id with kernel symbol address */ +static int check_pseudo_btf_id(struct bpf_verifier_env *env, + struct bpf_insn *insn, + struct bpf_insn_aux_data *aux) { - return (map->map_type != BPF_MAP_TYPE_HASH && - map->map_type != BPF_MAP_TYPE_PERCPU_HASH && - map->map_type != BPF_MAP_TYPE_HASH_OF_MAPS) || - !(map->map_flags & BPF_F_NO_PREALLOC); + const struct btf_var_secinfo *vsi; + const struct btf_type *datasec; + struct btf_mod_pair *btf_mod; + const struct btf_type *t; + const char *sym_name; + bool percpu = false; + u32 type, id = insn->imm; + struct btf *btf; + s32 datasec_id; + u64 addr; + int i, btf_fd, err; + + btf_fd = insn[1].imm; + if (btf_fd) { + btf = btf_get_by_fd(btf_fd); + if (IS_ERR(btf)) { + verbose(env, "invalid module BTF object FD specified.\n"); + return -EINVAL; + } + } else { + if (!btf_vmlinux) { + verbose(env, "kernel is missing BTF, make sure CONFIG_DEBUG_INFO_BTF=y is specified in Kconfig.\n"); + return -EINVAL; + } + btf = btf_vmlinux; + btf_get(btf); + } + + t = btf_type_by_id(btf, id); + if (!t) { + verbose(env, "ldimm64 insn specifies invalid btf_id %d.\n", id); + err = -ENOENT; + goto err_put; + } + + if (!btf_type_is_var(t)) { + verbose(env, "pseudo btf_id %d in ldimm64 isn't KIND_VAR.\n", id); + err = -EINVAL; + goto err_put; + } + + sym_name = btf_name_by_offset(btf, t->name_off); + addr = kallsyms_lookup_name(sym_name); + if (!addr) { + verbose(env, "ldimm64 failed to find the address for kernel symbol '%s'.\n", + sym_name); + err = -ENOENT; + goto err_put; + } + + datasec_id = find_btf_percpu_datasec(btf); + if (datasec_id > 0) { + datasec = btf_type_by_id(btf, datasec_id); + for_each_vsi(i, datasec, vsi) { + if (vsi->type == id) { + percpu = true; + break; + } + } + } + + insn[0].imm = (u32)addr; + insn[1].imm = addr >> 32; + + type = t->type; + t = btf_type_skip_modifiers(btf, type, NULL); + if (percpu) { + aux->btf_var.reg_type = PTR_TO_BTF_ID | MEM_PERCPU; + aux->btf_var.btf = btf; + aux->btf_var.btf_id = type; + } else if (!btf_type_is_struct(t)) { + const struct btf_type *ret; + const char *tname; + u32 tsize; + + /* resolve the type size of ksym. */ + ret = btf_resolve_size(btf, t, &tsize); + if (IS_ERR(ret)) { + tname = btf_name_by_offset(btf, t->name_off); + verbose(env, "ldimm64 unable to resolve the size of type '%s': %ld\n", + tname, PTR_ERR(ret)); + err = -EINVAL; + goto err_put; + } + aux->btf_var.reg_type = PTR_TO_MEM | MEM_RDONLY; + aux->btf_var.mem_size = tsize; + } else { + aux->btf_var.reg_type = PTR_TO_BTF_ID; + aux->btf_var.btf = btf; + aux->btf_var.btf_id = type; + } + + /* check whether we recorded this BTF (and maybe module) already */ + for (i = 0; i < env->used_btf_cnt; i++) { + if (env->used_btfs[i].btf == btf) { + btf_put(btf); + return 0; + } + } + + if (env->used_btf_cnt >= MAX_USED_BTFS) { + err = -E2BIG; + goto err_put; + } + + btf_mod = &env->used_btfs[env->used_btf_cnt]; + btf_mod->btf = btf; + btf_mod->module = NULL; + + /* if we reference variables from kernel module, bump its refcount */ + if (btf_is_module(btf)) { + btf_mod->module = btf_try_get_module(btf); + if (!btf_mod->module) { + err = -ENXIO; + goto err_put; + } + } + + env->used_btf_cnt++; + + return 0; +err_put: + btf_put(btf); + return err; } static bool is_tracing_prog_type(enum bpf_prog_type type) @@ -8133,6 +12659,7 @@ static bool is_tracing_prog_type(enum bpf_prog_type type) case BPF_PROG_TYPE_TRACEPOINT: case BPF_PROG_TYPE_PERF_EVENT: case BPF_PROG_TYPE_RAW_TRACEPOINT: + case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE: return true; default: return false; @@ -8144,28 +12671,30 @@ static int check_map_prog_compatibility(struct bpf_verifier_env *env, struct bpf_prog *prog) { - /* Make sure that BPF_PROG_TYPE_PERF_EVENT programs only use - * preallocated hash maps, since doing memory allocation - * in overflow_handler can crash depending on where nmi got - * triggered. - */ - if (prog->type == BPF_PROG_TYPE_PERF_EVENT) { - if (!check_map_prealloc(map)) { - verbose(env, "perf_event programs can only use preallocated hash map\n"); + enum bpf_prog_type prog_type = resolve_prog_type(prog); + + if (map_value_has_spin_lock(map)) { + if (prog_type == BPF_PROG_TYPE_SOCKET_FILTER) { + verbose(env, "socket filter progs cannot use bpf_spin_lock yet\n"); return -EINVAL; } - if (map->inner_map_meta && - !check_map_prealloc(map->inner_map_meta)) { - verbose(env, "perf_event programs can only use preallocated inner hash map\n"); + + if (is_tracing_prog_type(prog_type)) { + verbose(env, "tracing progs cannot use bpf_spin_lock yet\n"); + return -EINVAL; + } + + if (prog->aux->sleepable) { + verbose(env, "sleepable progs cannot use bpf_spin_lock yet\n"); return -EINVAL; } } - if ((is_tracing_prog_type(prog->type) || - prog->type == BPF_PROG_TYPE_SOCKET_FILTER) && - map_value_has_spin_lock(map)) { - verbose(env, "tracing progs cannot use bpf_spin_lock yet\n"); - return -EINVAL; + if (map_value_has_timer(map)) { + if (is_tracing_prog_type(prog_type)) { + verbose(env, "tracing progs cannot use bpf_timer yet\n"); + return -EINVAL; + } } if ((bpf_prog_is_dev_bound(prog->aux) || bpf_map_is_dev_bound(map)) && @@ -8179,6 +12708,28 @@ static int check_map_prog_compatibility(struct bpf_verifier_env *env, return -EINVAL; } + if (prog->aux->sleepable) + switch (map->map_type) { + case BPF_MAP_TYPE_HASH: + case BPF_MAP_TYPE_LRU_HASH: + case BPF_MAP_TYPE_ARRAY: + case BPF_MAP_TYPE_PERCPU_HASH: + case BPF_MAP_TYPE_PERCPU_ARRAY: + case BPF_MAP_TYPE_LRU_PERCPU_HASH: + case BPF_MAP_TYPE_ARRAY_OF_MAPS: + case BPF_MAP_TYPE_HASH_OF_MAPS: + case BPF_MAP_TYPE_RINGBUF: + case BPF_MAP_TYPE_USER_RINGBUF: + case BPF_MAP_TYPE_INODE_STORAGE: + case BPF_MAP_TYPE_SK_STORAGE: + case BPF_MAP_TYPE_TASK_STORAGE: + break; + default: + verbose(env, + "Sleepable programs can only use array, hash, and ringbuf maps\n"); + return -EINVAL; + } + return 0; } @@ -8188,10 +12739,14 @@ static bool bpf_map_is_cgroup_storage(struct bpf_map *map) map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE); } -/* look for pseudo eBPF instructions that access map FDs and - * replace them with actual map pointers +/* find and rewrite pseudo imm in ld_imm64 instructions: + * + * 1. if it accesses map FD, replace it with actual map pointer. + * 2. if it accesses btf_id of a VAR, replace it with pointer to the var. + * + * NOTE: btf_vmlinux is required for converting pseudo btf_id. */ -static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env) +static int resolve_pseudo_ldimm64(struct bpf_verifier_env *env) { struct bpf_insn *insn = env->prog->insnsi; int insn_cnt = env->prog->len; @@ -8208,18 +12763,12 @@ static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env) return -EINVAL; } - if (BPF_CLASS(insn->code) == BPF_STX && - ((BPF_MODE(insn->code) != BPF_MEM && - BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) { - verbose(env, "BPF_STX uses reserved fields\n"); - return -EINVAL; - } - if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) { struct bpf_insn_aux_data *aux; struct bpf_map *map; struct fd f; u64 addr; + u32 fd; if (i == insn_cnt - 1 || insn[1].code != 0 || insn[1].dst_reg != 0 || insn[1].src_reg != 0 || @@ -8232,19 +12781,55 @@ static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env) /* valid generic load 64-bit imm */ goto next_insn; + if (insn[0].src_reg == BPF_PSEUDO_BTF_ID) { + aux = &env->insn_aux_data[i]; + err = check_pseudo_btf_id(env, insn, aux); + if (err) + return err; + goto next_insn; + } + + if (insn[0].src_reg == BPF_PSEUDO_FUNC) { + aux = &env->insn_aux_data[i]; + aux->ptr_type = PTR_TO_FUNC; + goto next_insn; + } + /* In final convert_pseudo_ld_imm64() step, this is * converted into regular 64-bit imm load insn. */ - if ((insn[0].src_reg != BPF_PSEUDO_MAP_FD && - insn[0].src_reg != BPF_PSEUDO_MAP_VALUE) || - (insn[0].src_reg == BPF_PSEUDO_MAP_FD && - insn[1].imm != 0)) { - verbose(env, - "unrecognized bpf_ld_imm64 insn\n"); + switch (insn[0].src_reg) { + case BPF_PSEUDO_MAP_VALUE: + case BPF_PSEUDO_MAP_IDX_VALUE: + break; + case BPF_PSEUDO_MAP_FD: + case BPF_PSEUDO_MAP_IDX: + if (insn[1].imm == 0) + break; + fallthrough; + default: + verbose(env, "unrecognized bpf_ld_imm64 insn\n"); return -EINVAL; } - f = fdget(insn[0].imm); + switch (insn[0].src_reg) { + case BPF_PSEUDO_MAP_IDX_VALUE: + case BPF_PSEUDO_MAP_IDX: + if (bpfptr_is_null(env->fd_array)) { + verbose(env, "fd_idx without fd_array is invalid\n"); + return -EPROTO; + } + if (copy_from_bpfptr_offset(&fd, env->fd_array, + insn[0].imm * sizeof(fd), + sizeof(fd))) + return -EFAULT; + break; + default: + fd = insn[0].imm; + break; + } + + f = fdget(fd); map = __bpf_map_get(f); if (IS_ERR(map)) { verbose(env, "fd %d is not pointing to valid bpf_map\n", @@ -8259,7 +12844,8 @@ static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env) } aux = &env->insn_aux_data[i]; - if (insn->src_reg == BPF_PSEUDO_MAP_FD) { + if (insn[0].src_reg == BPF_PSEUDO_MAP_FD || + insn[0].src_reg == BPF_PSEUDO_MAP_IDX) { addr = (unsigned long)map; } else { u32 off = insn[1].imm; @@ -8350,6 +12936,13 @@ static void release_maps(struct bpf_verifier_env *env) env->used_map_cnt); } +/* drop refcnt of maps used by the rejected program */ +static void release_btfs(struct bpf_verifier_env *env) +{ + __bpf_free_used_btfs(env->prog->aux, env->used_btfs, + env->used_btf_cnt); +} + /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */ static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env) { @@ -8357,20 +12950,26 @@ static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env) int insn_cnt = env->prog->len; int i; - for (i = 0; i < insn_cnt; i++, insn++) - if (insn->code == (BPF_LD | BPF_IMM | BPF_DW)) - insn->src_reg = 0; + for (i = 0; i < insn_cnt; i++, insn++) { + if (insn->code != (BPF_LD | BPF_IMM | BPF_DW)) + continue; + if (insn->src_reg == BPF_PSEUDO_FUNC) + continue; + insn->src_reg = 0; + } } /* single env->prog->insni[off] instruction was replaced with the range * insni[off, off + cnt). Adjust corresponding insn_aux_data by copying * [0, off) and [off, end) to new locations, so the patched range stays zero */ -static int adjust_insn_aux_data(struct bpf_verifier_env *env, - struct bpf_prog *new_prog, u32 off, u32 cnt) +static void adjust_insn_aux_data(struct bpf_verifier_env *env, + struct bpf_insn_aux_data *new_data, + struct bpf_prog *new_prog, u32 off, u32 cnt) { - struct bpf_insn_aux_data *new_data, *old_data = env->insn_aux_data; + struct bpf_insn_aux_data *old_data = env->insn_aux_data; struct bpf_insn *insn = new_prog->insnsi; + u32 old_seen = old_data[off].seen; u32 prog_len; int i; @@ -8381,22 +12980,19 @@ static int adjust_insn_aux_data(struct bpf_verifier_env *env, old_data[off].zext_dst = insn_has_def32(env, insn + off + cnt - 1); if (cnt == 1) - return 0; + return; prog_len = new_prog->len; - new_data = vzalloc(array_size(prog_len, - sizeof(struct bpf_insn_aux_data))); - if (!new_data) - return -ENOMEM; + memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off); memcpy(new_data + off + cnt - 1, old_data + off, sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1)); for (i = off; i < off + cnt - 1; i++) { - new_data[i].seen = env->pass_cnt; + /* Expand insni[off]'s seen count to the patched range. */ + new_data[i].seen = old_seen; new_data[i].zext_dst = insn_has_def32(env, insn + i); } env->insn_aux_data = new_data; vfree(old_data); - return 0; } static void adjust_subprog_starts(struct bpf_verifier_env *env, u32 off, u32 len) @@ -8413,10 +13009,32 @@ static void adjust_subprog_starts(struct bpf_verifier_env *env, u32 off, u32 len } } +static void adjust_poke_descs(struct bpf_prog *prog, u32 off, u32 len) +{ + struct bpf_jit_poke_descriptor *tab = prog->aux->poke_tab; + int i, sz = prog->aux->size_poke_tab; + struct bpf_jit_poke_descriptor *desc; + + for (i = 0; i < sz; i++) { + desc = &tab[i]; + if (desc->insn_idx <= off) + continue; + desc->insn_idx += len - 1; + } +} + static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off, const struct bpf_insn *patch, u32 len) { struct bpf_prog *new_prog; + struct bpf_insn_aux_data *new_data = NULL; + + if (len > 1) { + new_data = vzalloc(array_size(env->prog->len + len - 1, + sizeof(struct bpf_insn_aux_data))); + if (!new_data) + return NULL; + } new_prog = bpf_patch_insn_single(env->prog, off, patch, len); if (IS_ERR(new_prog)) { @@ -8424,11 +13042,12 @@ static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 of verbose(env, "insn %d cannot be patched due to 16-bit range\n", env->insn_aux_data[off].orig_idx); + vfree(new_data); return NULL; } - if (adjust_insn_aux_data(env, new_prog, off, len)) - return NULL; + adjust_insn_aux_data(env, new_data, new_prog, off, len); adjust_subprog_starts(env, off, len); + adjust_poke_descs(new_prog, off, len); return new_prog; } @@ -8602,6 +13221,7 @@ static void sanitize_dead_code(struct bpf_verifier_env *env) if (aux_data[i].seen) continue; memcpy(insn + i, &trap, sizeof(trap)); + aux_data[i].zext_dst = false; } } @@ -8708,8 +13328,10 @@ static int opt_subreg_zext_lo32_rnd_hi32(struct bpf_verifier_env *env, for (i = 0; i < len; i++) { int adj_idx = i + delta; struct bpf_insn insn; + int load_reg; insn = insns[adj_idx]; + load_reg = insn_def_regno(&insn); if (!aux[adj_idx].zext_dst) { u8 code, class; u32 imm_rnd; @@ -8719,14 +13341,14 @@ static int opt_subreg_zext_lo32_rnd_hi32(struct bpf_verifier_env *env, code = insn.code; class = BPF_CLASS(code); - if (insn_no_def(&insn)) + if (load_reg == -1) continue; /* NOTE: arg "reg" (the fourth one) is only used for - * BPF_STX which has been ruled out in above - * check, it is safe to pass NULL here. + * BPF_STX + SRC_OP, so it is safe to pass NULL + * here. */ - if (is_reg64(env, &insn, insn.dst_reg, NULL, DST_OP)) { + if (is_reg64(env, &insn, load_reg, NULL, DST_OP)) { if (class == BPF_LD && BPF_MODE(code) == BPF_IMM) i++; @@ -8738,21 +13360,36 @@ static int opt_subreg_zext_lo32_rnd_hi32(struct bpf_verifier_env *env, aux[adj_idx].ptr_type == PTR_TO_CTX) continue; - imm_rnd = get_random_int(); + imm_rnd = get_random_u32(); rnd_hi32_patch[0] = insn; rnd_hi32_patch[1].imm = imm_rnd; - rnd_hi32_patch[3].dst_reg = insn.dst_reg; + rnd_hi32_patch[3].dst_reg = load_reg; patch = rnd_hi32_patch; patch_len = 4; goto apply_patch_buffer; } - if (!bpf_jit_needs_zext()) + /* Add in an zero-extend instruction if a) the JIT has requested + * it or b) it's a CMPXCHG. + * + * The latter is because: BPF_CMPXCHG always loads a value into + * R0, therefore always zero-extends. However some archs' + * equivalent instruction only does this load when the + * comparison is successful. This detail of CMPXCHG is + * orthogonal to the general zero-extension behaviour of the + * CPU, so it's treated independently of bpf_jit_needs_zext. + */ + if (!bpf_jit_needs_zext() && !is_cmpxchg_insn(&insn)) continue; + if (WARN_ON(load_reg == -1)) { + verbose(env, "verifier bug. zext_dst is set, but no reg is defined\n"); + return -EFAULT; + } + zext_patch[0] = insn; - zext_patch[1].dst_reg = insn.dst_reg; - zext_patch[1].src_reg = insn.dst_reg; + zext_patch[1].dst_reg = load_reg; + zext_patch[1].src_reg = load_reg; patch = zext_patch; patch_len = 2; apply_patch_buffer: @@ -8811,35 +13448,33 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) for (i = 0; i < insn_cnt; i++, insn++) { bpf_convert_ctx_access_t convert_ctx_access; + bool ctx_access; if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) || insn->code == (BPF_LDX | BPF_MEM | BPF_H) || insn->code == (BPF_LDX | BPF_MEM | BPF_W) || - insn->code == (BPF_LDX | BPF_MEM | BPF_DW)) + insn->code == (BPF_LDX | BPF_MEM | BPF_DW)) { type = BPF_READ; - else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) || - insn->code == (BPF_STX | BPF_MEM | BPF_H) || - insn->code == (BPF_STX | BPF_MEM | BPF_W) || - insn->code == (BPF_STX | BPF_MEM | BPF_DW)) + ctx_access = true; + } else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) || + insn->code == (BPF_STX | BPF_MEM | BPF_H) || + insn->code == (BPF_STX | BPF_MEM | BPF_W) || + insn->code == (BPF_STX | BPF_MEM | BPF_DW) || + insn->code == (BPF_ST | BPF_MEM | BPF_B) || + insn->code == (BPF_ST | BPF_MEM | BPF_H) || + insn->code == (BPF_ST | BPF_MEM | BPF_W) || + insn->code == (BPF_ST | BPF_MEM | BPF_DW)) { type = BPF_WRITE; - else + ctx_access = BPF_CLASS(insn->code) == BPF_STX; + } else { continue; + } if (type == BPF_WRITE && - env->insn_aux_data[i + delta].sanitize_stack_off) { + env->insn_aux_data[i + delta].sanitize_stack_spill) { struct bpf_insn patch[] = { - /* Sanitize suspicious stack slot with zero. - * There are no memory dependencies for this store, - * since it's only using frame pointer and immediate - * constant of zero - */ - BPF_ST_MEM(BPF_DW, BPF_REG_FP, - env->insn_aux_data[i + delta].sanitize_stack_off, - 0), - /* the original STX instruction will immediately - * overwrite the same stack slot with appropriate value - */ *insn, + BPF_ST_NOSPEC(), }; cnt = ARRAY_SIZE(patch); @@ -8853,7 +13488,10 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) continue; } - switch (env->insn_aux_data[i + delta].ptr_type) { + if (!ctx_access) + continue; + + switch ((int)env->insn_aux_data[i + delta].ptr_type) { case PTR_TO_CTX: if (!ops->convert_ctx_access) continue; @@ -8870,13 +13508,11 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) convert_ctx_access = bpf_xdp_sock_convert_ctx_access; break; case PTR_TO_BTF_ID: + case PTR_TO_BTF_ID | PTR_UNTRUSTED: if (type == BPF_READ) { insn->code = BPF_LDX | BPF_PROBE_MEM | BPF_SIZE((insn)->code); env->prog->aux->num_exentries++; - } else if (env->prog->type != BPF_PROG_TYPE_STRUCT_OPS) { - verbose(env, "Writes through BTF pointers are not allowed\n"); - return -EINVAL; } continue; default: @@ -8924,6 +13560,10 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) if (is_narrower_load && size < target_size) { u8 shift = bpf_ctx_narrow_access_offset( off, size, size_default) * 8; + if (shift && cnt + 1 >= ARRAY_SIZE(insn_buf)) { + verbose(env, "bpf verifier narrow ctx load misconfigured\n"); + return -EINVAL; + } if (ctx_field_size <= 4) { if (shift) insn_buf[cnt++] = BPF_ALU32_IMM(BPF_RSH, @@ -8959,17 +13599,18 @@ static int jit_subprogs(struct bpf_verifier_env *env) { struct bpf_prog *prog = env->prog, **func, *tmp; int i, j, subprog_start, subprog_end = 0, len, subprog; + struct bpf_map *map_ptr; struct bpf_insn *insn; void *old_bpf_func; - int err; + int err, num_exentries; if (env->subprog_cnt <= 1) return 0; for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) { - if (insn->code != (BPF_JMP | BPF_CALL) || - insn->src_reg != BPF_PSEUDO_CALL) + if (!bpf_pseudo_func(insn) && !bpf_pseudo_call(insn)) continue; + /* Upon error here we cannot fall back to interpreter but * need a hard reject of the program. Thus -EFAULT is * propagated in any case. @@ -8990,6 +13631,12 @@ static int jit_subprogs(struct bpf_verifier_env *env) env->insn_aux_data[i].call_imm = insn->imm; /* point imm to __bpf_call_base+1 from JITs point of view */ insn->imm = 1; + if (bpf_pseudo_func(insn)) + /* jit (e.g. x86_64) may emit fewer instructions + * if it learns a u32 imm is the same as a u64 imm. + * Force a non zero here. + */ + insn[1].imm = 1; } err = bpf_prog_alloc_jited_linfo(prog); @@ -9006,10 +13653,10 @@ static int jit_subprogs(struct bpf_verifier_env *env) subprog_end = env->subprog_info[i + 1].start; len = subprog_end - subprog_start; - /* BPF_PROG_RUN doesn't call subprogs directly, + /* bpf_prog_run() doesn't call subprogs directly, * hence main prog stats include the runtime of subprogs. * subprogs don't have IDs and not reachable via prog_get_next_id - * func[i]->aux->stats will never be accessed and stays NULL + * func[i]->stats will never be accessed and stays NULL */ func[i] = bpf_prog_alloc_no_stats(bpf_prog_size(len), GFP_USER); if (!func[i]) @@ -9022,20 +13669,41 @@ static int jit_subprogs(struct bpf_verifier_env *env) goto out_free; func[i]->is_func = 1; func[i]->aux->func_idx = i; - /* the btf and func_info will be freed only at prog->aux */ + /* Below members will be freed only at prog->aux */ func[i]->aux->btf = prog->aux->btf; func[i]->aux->func_info = prog->aux->func_info; + func[i]->aux->func_info_cnt = prog->aux->func_info_cnt; + func[i]->aux->poke_tab = prog->aux->poke_tab; + func[i]->aux->size_poke_tab = prog->aux->size_poke_tab; + + for (j = 0; j < prog->aux->size_poke_tab; j++) { + struct bpf_jit_poke_descriptor *poke; + + poke = &prog->aux->poke_tab[j]; + if (poke->insn_idx < subprog_end && + poke->insn_idx >= subprog_start) + poke->aux = func[i]->aux; + } - /* Use bpf_prog_F_tag to indicate functions in stack traces. - * Long term would need debug info to populate names - */ func[i]->aux->name[0] = 'F'; func[i]->aux->stack_depth = env->subprog_info[i].stack_depth; func[i]->jit_requested = 1; + func[i]->blinding_requested = prog->blinding_requested; + func[i]->aux->kfunc_tab = prog->aux->kfunc_tab; + func[i]->aux->kfunc_btf_tab = prog->aux->kfunc_btf_tab; func[i]->aux->linfo = prog->aux->linfo; func[i]->aux->nr_linfo = prog->aux->nr_linfo; func[i]->aux->jited_linfo = prog->aux->jited_linfo; func[i]->aux->linfo_idx = env->subprog_info[i].linfo_idx; + num_exentries = 0; + insn = func[i]->insnsi; + for (j = 0; j < func[i]->len; j++, insn++) { + if (BPF_CLASS(insn->code) == BPF_LDX && + BPF_MODE(insn->code) == BPF_PROBE_MEM) + num_exentries++; + } + func[i]->aux->num_exentries = num_exentries; + func[i]->aux->tail_call_reachable = env->subprog_info[i].tail_call_reachable; func[i] = bpf_int_jit_compile(func[i]); if (!func[i]->jited) { err = -ENOTSUPP; @@ -9043,6 +13711,7 @@ static int jit_subprogs(struct bpf_verifier_env *env) } cond_resched(); } + /* at this point all bpf functions were successfully JITed * now populate all bpf_calls with correct addresses and * run last pass of JIT @@ -9050,12 +13719,16 @@ static int jit_subprogs(struct bpf_verifier_env *env) for (i = 0; i < env->subprog_cnt; i++) { insn = func[i]->insnsi; for (j = 0; j < func[i]->len; j++, insn++) { - if (insn->code != (BPF_JMP | BPF_CALL) || - insn->src_reg != BPF_PSEUDO_CALL) + if (bpf_pseudo_func(insn)) { + subprog = insn->off; + insn[0].imm = (u32)(long)func[subprog]->bpf_func; + insn[1].imm = ((u64)(long)func[subprog]->bpf_func) >> 32; + continue; + } + if (!bpf_pseudo_call(insn)) continue; subprog = insn->off; - insn->imm = BPF_CAST_CALL(func[subprog]->bpf_func) - - __bpf_call_base; + insn->imm = BPF_CALL_IMM(func[subprog]->bpf_func); } /* we use the aux data to keep a list of the start addresses @@ -9096,8 +13769,13 @@ static int jit_subprogs(struct bpf_verifier_env *env) * later look the same as if they were interpreted only. */ for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) { - if (insn->code != (BPF_JMP | BPF_CALL) || - insn->src_reg != BPF_PSEUDO_CALL) + if (bpf_pseudo_func(insn)) { + insn[0].imm = env->insn_aux_data[i].call_imm; + insn[1].imm = insn->off; + insn->off = 0; + continue; + } + if (!bpf_pseudo_call(insn)) continue; insn->off = env->insn_aux_data[i].call_imm; subprog = find_subprog(env, i + insn->off + 1); @@ -9106,26 +13784,42 @@ static int jit_subprogs(struct bpf_verifier_env *env) prog->jited = 1; prog->bpf_func = func[0]->bpf_func; + prog->jited_len = func[0]->jited_len; prog->aux->func = func; prog->aux->func_cnt = env->subprog_cnt; - bpf_prog_free_unused_jited_linfo(prog); + bpf_prog_jit_attempt_done(prog); return 0; out_free: - for (i = 0; i < env->subprog_cnt; i++) - if (func[i]) - bpf_jit_free(func[i]); + /* We failed JIT'ing, so at this point we need to unregister poke + * descriptors from subprogs, so that kernel is not attempting to + * patch it anymore as we're freeing the subprog JIT memory. + */ + for (i = 0; i < prog->aux->size_poke_tab; i++) { + map_ptr = prog->aux->poke_tab[i].tail_call.map; + map_ptr->ops->map_poke_untrack(map_ptr, prog->aux); + } + /* At this point we're guaranteed that poke descriptors are not + * live anymore. We can just unlink its descriptor table as it's + * released with the main prog. + */ + for (i = 0; i < env->subprog_cnt; i++) { + if (!func[i]) + continue; + func[i]->aux->poke_tab = NULL; + bpf_jit_free(func[i]); + } kfree(func); out_undo_insn: /* cleanup main prog to be interpreted */ prog->jit_requested = 0; + prog->blinding_requested = 0; for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) { - if (insn->code != (BPF_JMP | BPF_CALL) || - insn->src_reg != BPF_PSEUDO_CALL) + if (!bpf_pseudo_call(insn)) continue; insn->off = 0; insn->imm = env->insn_aux_data[i].call_imm; } - bpf_prog_free_jited_linfo(prog); + bpf_prog_jit_attempt_done(prog); return err; } @@ -9134,6 +13828,7 @@ static int fixup_call_args(struct bpf_verifier_env *env) #ifndef CONFIG_BPF_JIT_ALWAYS_ON struct bpf_prog *prog = env->prog; struct bpf_insn *insn = prog->insnsi; + bool has_kfunc_call = bpf_prog_has_kfunc_call(prog); int i, depth; #endif int err = 0; @@ -9147,9 +13842,27 @@ static int fixup_call_args(struct bpf_verifier_env *env) return err; } #ifndef CONFIG_BPF_JIT_ALWAYS_ON + if (has_kfunc_call) { + verbose(env, "calling kernel functions are not allowed in non-JITed programs\n"); + return -EINVAL; + } + if (env->subprog_cnt > 1 && env->prog->aux->tail_call_reachable) { + /* When JIT fails the progs with bpf2bpf calls and tail_calls + * have to be rejected, since interpreter doesn't support them yet. + */ + verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n"); + return -EINVAL; + } for (i = 0; i < prog->len; i++, insn++) { - if (insn->code != (BPF_JMP | BPF_CALL) || - insn->src_reg != BPF_PSEUDO_CALL) + if (bpf_pseudo_func(insn)) { + /* When JIT fails the progs with callback calls + * have to be rejected, since interpreter doesn't support them yet. + */ + verbose(env, "callbacks are not allowed in non-JITed programs\n"); + return -EINVAL; + } + + if (!bpf_pseudo_call(insn)) continue; depth = get_callee_stack_depth(env, insn, i); if (depth < 0) @@ -9161,15 +13874,39 @@ static int fixup_call_args(struct bpf_verifier_env *env) return err; } -/* fixup insn->imm field of bpf_call instructions - * and inline eligible helpers as explicit sequence of BPF instructions - * - * this function is called after eBPF program passed verification +static int fixup_kfunc_call(struct bpf_verifier_env *env, + struct bpf_insn *insn) +{ + const struct bpf_kfunc_desc *desc; + + if (!insn->imm) { + verbose(env, "invalid kernel function call not eliminated in verifier pass\n"); + return -EINVAL; + } + + /* insn->imm has the btf func_id. Replace it with + * an address (relative to __bpf_base_call). + */ + desc = find_kfunc_desc(env->prog, insn->imm, insn->off); + if (!desc) { + verbose(env, "verifier internal error: kernel function descriptor not found for func_id %u\n", + insn->imm); + return -EFAULT; + } + + insn->imm = desc->imm; + + return 0; +} + +/* Do various post-verification rewrites in a single program pass. + * These rewrites simplify JIT and interpreter implementations. */ -static int fixup_bpf_calls(struct bpf_verifier_env *env) +static int do_misc_fixups(struct bpf_verifier_env *env) { struct bpf_prog *prog = env->prog; - bool expect_blinding = bpf_jit_blinding_enabled(prog); + enum bpf_attach_type eatype = prog->expected_attach_type; + enum bpf_prog_type prog_type = resolve_prog_type(prog); struct bpf_insn *insn = prog->insnsi; const struct bpf_func_proto *fn; const int insn_cnt = prog->len; @@ -9181,35 +13918,36 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) int i, ret, cnt, delta = 0; for (i = 0; i < insn_cnt; i++, insn++) { + /* Make divide-by-zero exceptions impossible. */ if (insn->code == (BPF_ALU64 | BPF_MOD | BPF_X) || insn->code == (BPF_ALU64 | BPF_DIV | BPF_X) || insn->code == (BPF_ALU | BPF_MOD | BPF_X) || insn->code == (BPF_ALU | BPF_DIV | BPF_X)) { bool is64 = BPF_CLASS(insn->code) == BPF_ALU64; - struct bpf_insn mask_and_div[] = { - BPF_MOV32_REG(insn->src_reg, insn->src_reg), - /* Rx div 0 -> 0 */ - BPF_JMP_IMM(BPF_JNE, insn->src_reg, 0, 2), + bool isdiv = BPF_OP(insn->code) == BPF_DIV; + struct bpf_insn *patchlet; + struct bpf_insn chk_and_div[] = { + /* [R,W]x div 0 -> 0 */ + BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) | + BPF_JNE | BPF_K, insn->src_reg, + 0, 2, 0), BPF_ALU32_REG(BPF_XOR, insn->dst_reg, insn->dst_reg), BPF_JMP_IMM(BPF_JA, 0, 0, 1), *insn, }; - struct bpf_insn mask_and_mod[] = { - BPF_MOV32_REG(insn->src_reg, insn->src_reg), - /* Rx mod 0 -> Rx */ - BPF_JMP_IMM(BPF_JEQ, insn->src_reg, 0, 1), + struct bpf_insn chk_and_mod[] = { + /* [R,W]x mod 0 -> [R,W]x */ + BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) | + BPF_JEQ | BPF_K, insn->src_reg, + 0, 1 + (is64 ? 0 : 1), 0), *insn, + BPF_JMP_IMM(BPF_JA, 0, 0, 1), + BPF_MOV32_REG(insn->dst_reg, insn->dst_reg), }; - struct bpf_insn *patchlet; - if (insn->code == (BPF_ALU64 | BPF_DIV | BPF_X) || - insn->code == (BPF_ALU | BPF_DIV | BPF_X)) { - patchlet = mask_and_div + (is64 ? 1 : 0); - cnt = ARRAY_SIZE(mask_and_div) - (is64 ? 1 : 0); - } else { - patchlet = mask_and_mod + (is64 ? 1 : 0); - cnt = ARRAY_SIZE(mask_and_mod) - (is64 ? 1 : 0); - } + patchlet = isdiv ? chk_and_div : chk_and_mod; + cnt = isdiv ? ARRAY_SIZE(chk_and_div) : + ARRAY_SIZE(chk_and_mod) - (is64 ? 2 : 0); new_prog = bpf_patch_insn_data(env, i + delta, patchlet, cnt); if (!new_prog) @@ -9221,6 +13959,7 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) continue; } + /* Implement LD_ABS and LD_IND with a rewrite, if supported by the program type. */ if (BPF_CLASS(insn->code) == BPF_LD && (BPF_MODE(insn->code) == BPF_ABS || BPF_MODE(insn->code) == BPF_IND)) { @@ -9240,13 +13979,13 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) continue; } + /* Rewrite pointer arithmetic to mitigate speculation attacks. */ if (insn->code == (BPF_ALU64 | BPF_ADD | BPF_X) || insn->code == (BPF_ALU64 | BPF_SUB | BPF_X)) { const u8 code_add = BPF_ALU64 | BPF_ADD | BPF_X; const u8 code_sub = BPF_ALU64 | BPF_SUB | BPF_X; - struct bpf_insn insn_buf[16]; struct bpf_insn *patch = &insn_buf[0]; - bool issrc, isneg; + bool issrc, isneg, isimm; u32 off_reg; aux = &env->insn_aux_data[i + delta]; @@ -9257,28 +13996,29 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) isneg = aux->alu_state & BPF_ALU_NEG_VALUE; issrc = (aux->alu_state & BPF_ALU_SANITIZE) == BPF_ALU_SANITIZE_SRC; + isimm = aux->alu_state & BPF_ALU_IMMEDIATE; off_reg = issrc ? insn->src_reg : insn->dst_reg; - if (isneg) - *patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1); - *patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit - 1); - *patch++ = BPF_ALU64_REG(BPF_SUB, BPF_REG_AX, off_reg); - *patch++ = BPF_ALU64_REG(BPF_OR, BPF_REG_AX, off_reg); - *patch++ = BPF_ALU64_IMM(BPF_NEG, BPF_REG_AX, 0); - *patch++ = BPF_ALU64_IMM(BPF_ARSH, BPF_REG_AX, 63); - if (issrc) { - *patch++ = BPF_ALU64_REG(BPF_AND, BPF_REG_AX, - off_reg); - insn->src_reg = BPF_REG_AX; + if (isimm) { + *patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit); } else { - *patch++ = BPF_ALU64_REG(BPF_AND, off_reg, - BPF_REG_AX); + if (isneg) + *patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1); + *patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit); + *patch++ = BPF_ALU64_REG(BPF_SUB, BPF_REG_AX, off_reg); + *patch++ = BPF_ALU64_REG(BPF_OR, BPF_REG_AX, off_reg); + *patch++ = BPF_ALU64_IMM(BPF_NEG, BPF_REG_AX, 0); + *patch++ = BPF_ALU64_IMM(BPF_ARSH, BPF_REG_AX, 63); + *patch++ = BPF_ALU64_REG(BPF_AND, BPF_REG_AX, off_reg); } + if (!issrc) + *patch++ = BPF_MOV64_REG(insn->dst_reg, insn->src_reg); + insn->src_reg = BPF_REG_AX; if (isneg) insn->code = insn->code == code_add ? code_sub : code_add; *patch++ = *insn; - if (issrc && isneg) + if (issrc && isneg && !isimm) *patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1); cnt = patch - insn_buf; @@ -9296,6 +14036,12 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) continue; if (insn->src_reg == BPF_PSEUDO_CALL) continue; + if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) { + ret = fixup_kfunc_call(env, insn); + if (ret) + return ret; + continue; + } if (insn->imm == BPF_FUNC_get_route_realm) prog->dst_needed = 1; @@ -9310,11 +14056,12 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) * the program array. */ prog->cb_access = 1; - env->prog->aux->stack_depth = MAX_BPF_STACK; - env->prog->aux->max_pkt_offset = MAX_PACKET_OFF; + if (!allow_tail_call_in_subprogs(env)) + prog->aux->stack_depth = MAX_BPF_STACK; + prog->aux->max_pkt_offset = MAX_PACKET_OFF; /* mark bpf_tail_call as different opcode to avoid - * conditional branch in the interpeter for every normal + * conditional branch in the interpreter for every normal * call and to prevent accidental JITing by JIT compiler * that doesn't support bpf_tail_call yet */ @@ -9322,7 +14069,7 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) insn->code = BPF_JMP | BPF_TAIL_CALL; aux = &env->insn_aux_data[i + delta]; - if (env->allow_ptr_leaks && !expect_blinding && + if (env->bpf_capable && !prog->blinding_requested && prog->jit_requested && !bpf_map_key_poisoned(aux) && !bpf_map_ptr_poisoned(aux) && @@ -9331,6 +14078,7 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) .reason = BPF_POKE_REASON_TAIL_CALL, .tail_call.map = BPF_MAP_PTR(aux->map_ptr_state), .tail_call.key = bpf_map_key_immediate(aux), + .insn_idx = i + delta, }; ret = bpf_jit_add_poke_descriptor(prog, &desc); @@ -9376,6 +14124,59 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) continue; } + if (insn->imm == BPF_FUNC_timer_set_callback) { + /* The verifier will process callback_fn as many times as necessary + * with different maps and the register states prepared by + * set_timer_callback_state will be accurate. + * + * The following use case is valid: + * map1 is shared by prog1, prog2, prog3. + * prog1 calls bpf_timer_init for some map1 elements + * prog2 calls bpf_timer_set_callback for some map1 elements. + * Those that were not bpf_timer_init-ed will return -EINVAL. + * prog3 calls bpf_timer_start for some map1 elements. + * Those that were not both bpf_timer_init-ed and + * bpf_timer_set_callback-ed will return -EINVAL. + */ + struct bpf_insn ld_addrs[2] = { + BPF_LD_IMM64(BPF_REG_3, (long)prog->aux), + }; + + insn_buf[0] = ld_addrs[0]; + insn_buf[1] = ld_addrs[1]; + insn_buf[2] = *insn; + cnt = 3; + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + goto patch_call_imm; + } + + if (insn->imm == BPF_FUNC_task_storage_get || + insn->imm == BPF_FUNC_sk_storage_get || + insn->imm == BPF_FUNC_inode_storage_get) { + if (env->prog->aux->sleepable) + insn_buf[0] = BPF_MOV64_IMM(BPF_REG_5, (__force __s32)GFP_KERNEL); + else + insn_buf[0] = BPF_MOV64_IMM(BPF_REG_5, (__force __s32)GFP_ATOMIC); + insn_buf[1] = *insn; + cnt = 2; + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + goto patch_call_imm; + } + /* BPF_EMIT_CALL() assumptions in some of the map_gen_lookup * and other inlining handlers are currently limited to 64 bit * only. @@ -9386,7 +14187,10 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) insn->imm == BPF_FUNC_map_delete_elem || insn->imm == BPF_FUNC_map_push_elem || insn->imm == BPF_FUNC_map_pop_elem || - insn->imm == BPF_FUNC_map_peek_elem)) { + insn->imm == BPF_FUNC_map_peek_elem || + insn->imm == BPF_FUNC_redirect_map || + insn->imm == BPF_FUNC_for_each_map_elem || + insn->imm == BPF_FUNC_map_lookup_percpu_elem)) { aux = &env->insn_aux_data[i + delta]; if (bpf_map_ptr_poisoned(aux)) goto patch_call_imm; @@ -9396,7 +14200,9 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) if (insn->imm == BPF_FUNC_map_lookup_elem && ops->map_gen_lookup) { cnt = ops->map_gen_lookup(map_ptr, insn_buf); - if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) { + if (cnt == -EOPNOTSUPP) + goto patch_map_ops_generic; + if (cnt <= 0 || cnt >= ARRAY_SIZE(insn_buf)) { verbose(env, "bpf verifier is misconfigured\n"); return -EINVAL; } @@ -9426,37 +14232,51 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) (int (*)(struct bpf_map *map, void *value))NULL)); BUILD_BUG_ON(!__same_type(ops->map_peek_elem, (int (*)(struct bpf_map *map, void *value))NULL)); + BUILD_BUG_ON(!__same_type(ops->map_redirect, + (int (*)(struct bpf_map *map, u32 ifindex, u64 flags))NULL)); + BUILD_BUG_ON(!__same_type(ops->map_for_each_callback, + (int (*)(struct bpf_map *map, + bpf_callback_t callback_fn, + void *callback_ctx, + u64 flags))NULL)); + BUILD_BUG_ON(!__same_type(ops->map_lookup_percpu_elem, + (void *(*)(struct bpf_map *map, void *key, u32 cpu))NULL)); +patch_map_ops_generic: switch (insn->imm) { case BPF_FUNC_map_lookup_elem: - insn->imm = BPF_CAST_CALL(ops->map_lookup_elem) - - __bpf_call_base; + insn->imm = BPF_CALL_IMM(ops->map_lookup_elem); continue; case BPF_FUNC_map_update_elem: - insn->imm = BPF_CAST_CALL(ops->map_update_elem) - - __bpf_call_base; + insn->imm = BPF_CALL_IMM(ops->map_update_elem); continue; case BPF_FUNC_map_delete_elem: - insn->imm = BPF_CAST_CALL(ops->map_delete_elem) - - __bpf_call_base; + insn->imm = BPF_CALL_IMM(ops->map_delete_elem); continue; case BPF_FUNC_map_push_elem: - insn->imm = BPF_CAST_CALL(ops->map_push_elem) - - __bpf_call_base; + insn->imm = BPF_CALL_IMM(ops->map_push_elem); continue; case BPF_FUNC_map_pop_elem: - insn->imm = BPF_CAST_CALL(ops->map_pop_elem) - - __bpf_call_base; + insn->imm = BPF_CALL_IMM(ops->map_pop_elem); continue; case BPF_FUNC_map_peek_elem: - insn->imm = BPF_CAST_CALL(ops->map_peek_elem) - - __bpf_call_base; + insn->imm = BPF_CALL_IMM(ops->map_peek_elem); + continue; + case BPF_FUNC_redirect_map: + insn->imm = BPF_CALL_IMM(ops->map_redirect); + continue; + case BPF_FUNC_for_each_map_elem: + insn->imm = BPF_CALL_IMM(ops->map_for_each_callback); + continue; + case BPF_FUNC_map_lookup_percpu_elem: + insn->imm = BPF_CALL_IMM(ops->map_lookup_percpu_elem); continue; } goto patch_call_imm; } + /* Implement bpf_jiffies64 inline. */ if (prog->jit_requested && BITS_PER_LONG == 64 && insn->imm == BPF_FUNC_jiffies64) { struct bpf_insn ld_jiffies_addr[2] = { @@ -9481,6 +14301,89 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) continue; } + /* Implement bpf_get_func_arg inline. */ + if (prog_type == BPF_PROG_TYPE_TRACING && + insn->imm == BPF_FUNC_get_func_arg) { + /* Load nr_args from ctx - 8 */ + insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8); + insn_buf[1] = BPF_JMP32_REG(BPF_JGE, BPF_REG_2, BPF_REG_0, 6); + insn_buf[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_2, 3); + insn_buf[3] = BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_1); + insn_buf[4] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_2, 0); + insn_buf[5] = BPF_STX_MEM(BPF_DW, BPF_REG_3, BPF_REG_0, 0); + insn_buf[6] = BPF_MOV64_IMM(BPF_REG_0, 0); + insn_buf[7] = BPF_JMP_A(1); + insn_buf[8] = BPF_MOV64_IMM(BPF_REG_0, -EINVAL); + cnt = 9; + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + + /* Implement bpf_get_func_ret inline. */ + if (prog_type == BPF_PROG_TYPE_TRACING && + insn->imm == BPF_FUNC_get_func_ret) { + if (eatype == BPF_TRACE_FEXIT || + eatype == BPF_MODIFY_RETURN) { + /* Load nr_args from ctx - 8 */ + insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8); + insn_buf[1] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_0, 3); + insn_buf[2] = BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_1); + insn_buf[3] = BPF_LDX_MEM(BPF_DW, BPF_REG_3, BPF_REG_0, 0); + insn_buf[4] = BPF_STX_MEM(BPF_DW, BPF_REG_2, BPF_REG_3, 0); + insn_buf[5] = BPF_MOV64_IMM(BPF_REG_0, 0); + cnt = 6; + } else { + insn_buf[0] = BPF_MOV64_IMM(BPF_REG_0, -EOPNOTSUPP); + cnt = 1; + } + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + + /* Implement get_func_arg_cnt inline. */ + if (prog_type == BPF_PROG_TYPE_TRACING && + insn->imm == BPF_FUNC_get_func_arg_cnt) { + /* Load nr_args from ctx - 8 */ + insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8); + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1); + if (!new_prog) + return -ENOMEM; + + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + + /* Implement bpf_get_func_ip inline. */ + if (prog_type == BPF_PROG_TYPE_TRACING && + insn->imm == BPF_FUNC_get_func_ip) { + /* Load IP address from ctx - 16 */ + insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -16); + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1); + if (!new_prog) + return -ENOMEM; + + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + patch_call_imm: fn = env->ops->get_func_proto(insn->imm, env->prog); /* all functions that have prototype and verifier allowed @@ -9512,6 +14415,144 @@ patch_call_imm: } } + sort_kfunc_descs_by_imm(env->prog); + + return 0; +} + +static struct bpf_prog *inline_bpf_loop(struct bpf_verifier_env *env, + int position, + s32 stack_base, + u32 callback_subprogno, + u32 *cnt) +{ + s32 r6_offset = stack_base + 0 * BPF_REG_SIZE; + s32 r7_offset = stack_base + 1 * BPF_REG_SIZE; + s32 r8_offset = stack_base + 2 * BPF_REG_SIZE; + int reg_loop_max = BPF_REG_6; + int reg_loop_cnt = BPF_REG_7; + int reg_loop_ctx = BPF_REG_8; + + struct bpf_prog *new_prog; + u32 callback_start; + u32 call_insn_offset; + s32 callback_offset; + + /* This represents an inlined version of bpf_iter.c:bpf_loop, + * be careful to modify this code in sync. + */ + struct bpf_insn insn_buf[] = { + /* Return error and jump to the end of the patch if + * expected number of iterations is too big. + */ + BPF_JMP_IMM(BPF_JLE, BPF_REG_1, BPF_MAX_LOOPS, 2), + BPF_MOV32_IMM(BPF_REG_0, -E2BIG), + BPF_JMP_IMM(BPF_JA, 0, 0, 16), + /* spill R6, R7, R8 to use these as loop vars */ + BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_6, r6_offset), + BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_7, r7_offset), + BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_8, r8_offset), + /* initialize loop vars */ + BPF_MOV64_REG(reg_loop_max, BPF_REG_1), + BPF_MOV32_IMM(reg_loop_cnt, 0), + BPF_MOV64_REG(reg_loop_ctx, BPF_REG_3), + /* loop header, + * if reg_loop_cnt >= reg_loop_max skip the loop body + */ + BPF_JMP_REG(BPF_JGE, reg_loop_cnt, reg_loop_max, 5), + /* callback call, + * correct callback offset would be set after patching + */ + BPF_MOV64_REG(BPF_REG_1, reg_loop_cnt), + BPF_MOV64_REG(BPF_REG_2, reg_loop_ctx), + BPF_CALL_REL(0), + /* increment loop counter */ + BPF_ALU64_IMM(BPF_ADD, reg_loop_cnt, 1), + /* jump to loop header if callback returned 0 */ + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, -6), + /* return value of bpf_loop, + * set R0 to the number of iterations + */ + BPF_MOV64_REG(BPF_REG_0, reg_loop_cnt), + /* restore original values of R6, R7, R8 */ + BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_10, r6_offset), + BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_10, r7_offset), + BPF_LDX_MEM(BPF_DW, BPF_REG_8, BPF_REG_10, r8_offset), + }; + + *cnt = ARRAY_SIZE(insn_buf); + new_prog = bpf_patch_insn_data(env, position, insn_buf, *cnt); + if (!new_prog) + return new_prog; + + /* callback start is known only after patching */ + callback_start = env->subprog_info[callback_subprogno].start; + /* Note: insn_buf[12] is an offset of BPF_CALL_REL instruction */ + call_insn_offset = position + 12; + callback_offset = callback_start - call_insn_offset - 1; + new_prog->insnsi[call_insn_offset].imm = callback_offset; + + return new_prog; +} + +static bool is_bpf_loop_call(struct bpf_insn *insn) +{ + return insn->code == (BPF_JMP | BPF_CALL) && + insn->src_reg == 0 && + insn->imm == BPF_FUNC_loop; +} + +/* For all sub-programs in the program (including main) check + * insn_aux_data to see if there are bpf_loop calls that require + * inlining. If such calls are found the calls are replaced with a + * sequence of instructions produced by `inline_bpf_loop` function and + * subprog stack_depth is increased by the size of 3 registers. + * This stack space is used to spill values of the R6, R7, R8. These + * registers are used to store the loop bound, counter and context + * variables. + */ +static int optimize_bpf_loop(struct bpf_verifier_env *env) +{ + struct bpf_subprog_info *subprogs = env->subprog_info; + int i, cur_subprog = 0, cnt, delta = 0; + struct bpf_insn *insn = env->prog->insnsi; + int insn_cnt = env->prog->len; + u16 stack_depth = subprogs[cur_subprog].stack_depth; + u16 stack_depth_roundup = round_up(stack_depth, 8) - stack_depth; + u16 stack_depth_extra = 0; + + for (i = 0; i < insn_cnt; i++, insn++) { + struct bpf_loop_inline_state *inline_state = + &env->insn_aux_data[i + delta].loop_inline_state; + + if (is_bpf_loop_call(insn) && inline_state->fit_for_inline) { + struct bpf_prog *new_prog; + + stack_depth_extra = BPF_REG_SIZE * 3 + stack_depth_roundup; + new_prog = inline_bpf_loop(env, + i + delta, + -(stack_depth + stack_depth_extra), + inline_state->callback_subprogno, + &cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = new_prog; + insn = new_prog->insnsi + i + delta; + } + + if (subprogs[cur_subprog + 1].start == i + delta + 1) { + subprogs[cur_subprog].stack_depth += stack_depth_extra; + cur_subprog++; + stack_depth = subprogs[cur_subprog].stack_depth; + stack_depth_roundup = round_up(stack_depth, 8) - stack_depth; + stack_depth_extra = 0; + } + } + + env->prog->aux->stack_depth = env->subprog_info[0].stack_depth; + return 0; } @@ -9545,36 +14586,9 @@ static void free_states(struct bpf_verifier_env *env) } } -/* The verifier is using insn_aux_data[] to store temporary data during - * verification and to store information for passes that run after the - * verification like dead code sanitization. do_check_common() for subprogram N - * may analyze many other subprograms. sanitize_insn_aux_data() clears all - * temporary data after do_check_common() finds that subprogram N cannot be - * verified independently. pass_cnt counts the number of times - * do_check_common() was run and insn->aux->seen tells the pass number - * insn_aux_data was touched. These variables are compared to clear temporary - * data from failed pass. For testing and experiments do_check_common() can be - * run multiple times even when prior attempt to verify is unsuccessful. - */ -static void sanitize_insn_aux_data(struct bpf_verifier_env *env) -{ - struct bpf_insn *insn = env->prog->insnsi; - struct bpf_insn_aux_data *aux; - int i, class; - - for (i = 0; i < env->prog->len; i++) { - class = BPF_CLASS(insn[i].code); - if (class != BPF_LDX && class != BPF_STX) - continue; - aux = &env->insn_aux_data[i]; - if (aux->seen != env->pass_cnt) - continue; - memset(aux, 0, offsetof(typeof(*aux), orig_idx)); - } -} - static int do_check_common(struct bpf_verifier_env *env, int subprog) { + bool pop_log = !(env->log.level & BPF_LOG_LEVEL2); struct bpf_verifier_state *state; struct bpf_reg_state *regs; int ret, i; @@ -9609,12 +14623,19 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog) mark_reg_known_zero(env, regs, i); else if (regs[i].type == SCALAR_VALUE) mark_reg_unknown(env, regs, i); + else if (base_type(regs[i].type) == PTR_TO_MEM) { + const u32 mem_size = regs[i].mem_size; + + mark_reg_known_zero(env, regs, i); + regs[i].mem_size = mem_size; + regs[i].id = ++env->id_gen; + } } } else { /* 1st arg to a function */ regs[BPF_REG_1].type = PTR_TO_CTX; mark_reg_known_zero(env, regs, BPF_REG_1); - ret = btf_check_func_arg_match(env, subprog, regs); + ret = btf_check_subprog_arg_match(env, subprog, regs); if (ret == -EFAULT) /* unlikely verifier bug. abort. * ret == 0 and ret < 0 are sadly acceptable for @@ -9637,11 +14658,10 @@ out: free_verifier_state(env->cur_state, true); env->cur_state = NULL; } - while (!pop_stack(env, NULL, NULL)); + while (!pop_stack(env, NULL, NULL, false)); + if (!ret && pop_log) + bpf_vlog_reset(&env->log, 0); free_states(env); - if (ret) - /* clean aux data in case subprog was rejected */ - sanitize_insn_aux_data(env); return ret; } @@ -9732,6 +14752,11 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env) u32 btf_id, member_idx; const char *mname; + if (!prog->gpl_compatible) { + verbose(env, "struct ops programs must have a GPL compatible license\n"); + return -EINVAL; + } + btf_id = prog->aux->attach_btf_id; st_ops = bpf_struct_ops_find(btf_id); if (!st_ops) { @@ -9774,47 +14799,67 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env) return 0; } +#define SECURITY_PREFIX "security_" -static int check_attach_btf_id(struct bpf_verifier_env *env) +static int check_attach_modify_return(unsigned long addr, const char *func_name) +{ + if (within_error_injection_list(addr) || + !strncmp(SECURITY_PREFIX, func_name, sizeof(SECURITY_PREFIX) - 1)) + return 0; + + return -EINVAL; +} + +/* list of non-sleepable functions that are otherwise on + * ALLOW_ERROR_INJECTION list + */ +BTF_SET_START(btf_non_sleepable_error_inject) +/* Three functions below can be called from sleepable and non-sleepable context. + * Assume non-sleepable from bpf safety point of view. + */ +BTF_ID(func, __filemap_add_folio) +BTF_ID(func, should_fail_alloc_page) +BTF_ID(func, should_failslab) +BTF_SET_END(btf_non_sleepable_error_inject) + +static int check_non_sleepable_error_inject(u32 btf_id) +{ + return btf_id_set_contains(&btf_non_sleepable_error_inject, btf_id); +} + +int bpf_check_attach_target(struct bpf_verifier_log *log, + const struct bpf_prog *prog, + const struct bpf_prog *tgt_prog, + u32 btf_id, + struct bpf_attach_target_info *tgt_info) { - struct bpf_prog *prog = env->prog; bool prog_extension = prog->type == BPF_PROG_TYPE_EXT; - struct bpf_prog *tgt_prog = prog->aux->linked_prog; - u32 btf_id = prog->aux->attach_btf_id; const char prefix[] = "btf_trace_"; int ret = 0, subprog = -1, i; - struct bpf_trampoline *tr; const struct btf_type *t; bool conservative = true; const char *tname; struct btf *btf; - long addr; - u64 key; - - if (prog->type == BPF_PROG_TYPE_STRUCT_OPS) - return check_struct_ops_btf_id(env); - - if (prog->type != BPF_PROG_TYPE_TRACING && !prog_extension) - return 0; + long addr = 0; if (!btf_id) { - verbose(env, "Tracing programs must provide btf_id\n"); + bpf_log(log, "Tracing programs must provide btf_id\n"); return -EINVAL; } - btf = bpf_prog_get_target_btf(prog); + btf = tgt_prog ? tgt_prog->aux->btf : prog->aux->attach_btf; if (!btf) { - verbose(env, + bpf_log(log, "FENTRY/FEXIT program can only be attached to another program annotated with BTF\n"); return -EINVAL; } t = btf_type_by_id(btf, btf_id); if (!t) { - verbose(env, "attach_btf_id %u is invalid\n", btf_id); + bpf_log(log, "attach_btf_id %u is invalid\n", btf_id); return -EINVAL; } tname = btf_name_by_offset(btf, t->name_off); if (!tname) { - verbose(env, "attach_btf_id %u doesn't have a name\n", btf_id); + bpf_log(log, "attach_btf_id %u doesn't have a name\n", btf_id); return -EINVAL; } if (tgt_prog) { @@ -9826,25 +14871,24 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) break; } if (subprog == -1) { - verbose(env, "Subprog %s doesn't exist\n", tname); + bpf_log(log, "Subprog %s doesn't exist\n", tname); return -EINVAL; } conservative = aux->func_info_aux[subprog].unreliable; if (prog_extension) { if (conservative) { - verbose(env, + bpf_log(log, "Cannot replace static functions\n"); return -EINVAL; } if (!prog->jit_requested) { - verbose(env, + bpf_log(log, "Extension programs should be JITed\n"); return -EINVAL; } - env->ops = bpf_verifier_ops[tgt_prog->type]; } if (!tgt_prog->jited) { - verbose(env, "Can attach to only JITed progs\n"); + bpf_log(log, "Can attach to only JITed progs\n"); return -EINVAL; } if (tgt_prog->type == prog->type) { @@ -9852,7 +14896,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) * Cannot attach program extension to another extension. * It's ok to attach fentry/fexit to extension program. */ - verbose(env, "Cannot recursively attach\n"); + bpf_log(log, "Cannot recursively attach\n"); return -EINVAL; } if (tgt_prog->type == BPF_PROG_TYPE_TRACING && @@ -9874,32 +14918,30 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) * reasonable stack size. Hence extending fentry is not * allowed. */ - verbose(env, "Cannot extend fentry/fexit\n"); + bpf_log(log, "Cannot extend fentry/fexit\n"); return -EINVAL; } - key = ((u64)aux->id) << 32 | btf_id; } else { if (prog_extension) { - verbose(env, "Cannot replace kernel functions\n"); + bpf_log(log, "Cannot replace kernel functions\n"); return -EINVAL; } - key = btf_id; } switch (prog->expected_attach_type) { case BPF_TRACE_RAW_TP: if (tgt_prog) { - verbose(env, + bpf_log(log, "Only FENTRY/FEXIT progs are attachable to another BPF prog\n"); return -EINVAL; } if (!btf_type_is_typedef(t)) { - verbose(env, "attach_btf_id %u is not a typedef\n", + bpf_log(log, "attach_btf_id %u is not a typedef\n", btf_id); return -EINVAL; } if (strncmp(prefix, tname, sizeof(prefix) - 1)) { - verbose(env, "attach_btf_id %u points to wrong type name %s\n", + bpf_log(log, "attach_btf_id %u points to wrong type name %s\n", btf_id, tname); return -EINVAL; } @@ -9913,49 +14955,53 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) /* should never happen in valid vmlinux build */ return -EINVAL; - /* remember two read only pointers that are valid for - * the life time of the kernel - */ - prog->aux->attach_func_name = tname; - prog->aux->attach_func_proto = t; - prog->aux->attach_btf_trace = true; - return 0; + break; + case BPF_TRACE_ITER: + if (!btf_type_is_func(t)) { + bpf_log(log, "attach_btf_id %u is not a function\n", + btf_id); + return -EINVAL; + } + t = btf_type_by_id(btf, t->type); + if (!btf_type_is_func_proto(t)) + return -EINVAL; + ret = btf_distill_func_proto(log, btf, t, tname, &tgt_info->fmodel); + if (ret) + return ret; + break; default: if (!prog_extension) return -EINVAL; - /* fallthrough */ + fallthrough; + case BPF_MODIFY_RETURN: + case BPF_LSM_MAC: + case BPF_LSM_CGROUP: case BPF_TRACE_FENTRY: case BPF_TRACE_FEXIT: if (!btf_type_is_func(t)) { - verbose(env, "attach_btf_id %u is not a function\n", + bpf_log(log, "attach_btf_id %u is not a function\n", btf_id); return -EINVAL; } if (prog_extension && - btf_check_type_match(env, prog, btf, t)) + btf_check_type_match(log, prog, btf, t)) return -EINVAL; t = btf_type_by_id(btf, t->type); if (!btf_type_is_func_proto(t)) return -EINVAL; - tr = bpf_trampoline_lookup(key); - if (!tr) - return -ENOMEM; - prog->aux->attach_func_name = tname; - /* t is either vmlinux type or another program's type */ - prog->aux->attach_func_proto = t; - mutex_lock(&tr->mutex); - if (tr->func.addr) { - prog->aux->trampoline = tr; - goto out; - } - if (tgt_prog && conservative) { - prog->aux->attach_func_proto = NULL; + + if ((prog->aux->saved_dst_prog_type || prog->aux->saved_dst_attach_type) && + (!tgt_prog || prog->aux->saved_dst_prog_type != tgt_prog->type || + prog->aux->saved_dst_attach_type != tgt_prog->expected_attach_type)) + return -EINVAL; + + if (tgt_prog && conservative) t = NULL; - } - ret = btf_distill_func_proto(&env->log, btf, t, - tname, &tr->func.model); + + ret = btf_distill_func_proto(log, btf, t, tname, &tgt_info->fmodel); if (ret < 0) - goto out; + return ret; + if (tgt_prog) { if (subprog == 0) addr = (long) tgt_prog->bpf_func; @@ -9964,25 +15010,162 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) } else { addr = kallsyms_lookup_name(tname); if (!addr) { - verbose(env, + bpf_log(log, "The address of function %s cannot be found\n", tname); - ret = -ENOENT; - goto out; + return -ENOENT; } } - tr->func.addr = (void *)addr; - prog->aux->trampoline = tr; -out: - mutex_unlock(&tr->mutex); - if (ret) - bpf_trampoline_put(tr); + + if (prog->aux->sleepable) { + ret = -EINVAL; + switch (prog->type) { + case BPF_PROG_TYPE_TRACING: + /* fentry/fexit/fmod_ret progs can be sleepable only if they are + * attached to ALLOW_ERROR_INJECTION and are not in denylist. + */ + if (!check_non_sleepable_error_inject(btf_id) && + within_error_injection_list(addr)) + ret = 0; + break; + case BPF_PROG_TYPE_LSM: + /* LSM progs check that they are attached to bpf_lsm_*() funcs. + * Only some of them are sleepable. + */ + if (bpf_lsm_is_sleepable_hook(btf_id)) + ret = 0; + break; + default: + break; + } + if (ret) { + bpf_log(log, "%s is not sleepable\n", tname); + return ret; + } + } else if (prog->expected_attach_type == BPF_MODIFY_RETURN) { + if (tgt_prog) { + bpf_log(log, "can't modify return codes of BPF programs\n"); + return -EINVAL; + } + ret = check_attach_modify_return(addr, tname); + if (ret) { + bpf_log(log, "%s() is not modifiable\n", tname); + return ret; + } + } + + break; + } + tgt_info->tgt_addr = addr; + tgt_info->tgt_name = tname; + tgt_info->tgt_type = t; + return 0; +} + +BTF_SET_START(btf_id_deny) +BTF_ID_UNUSED +#ifdef CONFIG_SMP +BTF_ID(func, migrate_disable) +BTF_ID(func, migrate_enable) +#endif +#if !defined CONFIG_PREEMPT_RCU && !defined CONFIG_TINY_RCU +BTF_ID(func, rcu_read_unlock_strict) +#endif +BTF_SET_END(btf_id_deny) + +static int check_attach_btf_id(struct bpf_verifier_env *env) +{ + struct bpf_prog *prog = env->prog; + struct bpf_prog *tgt_prog = prog->aux->dst_prog; + struct bpf_attach_target_info tgt_info = {}; + u32 btf_id = prog->aux->attach_btf_id; + struct bpf_trampoline *tr; + int ret; + u64 key; + + if (prog->type == BPF_PROG_TYPE_SYSCALL) { + if (prog->aux->sleepable) + /* attach_btf_id checked to be zero already */ + return 0; + verbose(env, "Syscall programs can only be sleepable\n"); + return -EINVAL; + } + + if (prog->aux->sleepable && prog->type != BPF_PROG_TYPE_TRACING && + prog->type != BPF_PROG_TYPE_LSM && prog->type != BPF_PROG_TYPE_KPROBE) { + verbose(env, "Only fentry/fexit/fmod_ret, lsm, and kprobe/uprobe programs can be sleepable\n"); + return -EINVAL; + } + + if (prog->type == BPF_PROG_TYPE_STRUCT_OPS) + return check_struct_ops_btf_id(env); + + if (prog->type != BPF_PROG_TYPE_TRACING && + prog->type != BPF_PROG_TYPE_LSM && + prog->type != BPF_PROG_TYPE_EXT) + return 0; + + ret = bpf_check_attach_target(&env->log, prog, tgt_prog, btf_id, &tgt_info); + if (ret) return ret; + + if (tgt_prog && prog->type == BPF_PROG_TYPE_EXT) { + /* to make freplace equivalent to their targets, they need to + * inherit env->ops and expected_attach_type for the rest of the + * verification + */ + env->ops = bpf_verifier_ops[tgt_prog->type]; + prog->expected_attach_type = tgt_prog->expected_attach_type; + } + + /* store info about the attachment target that will be used later */ + prog->aux->attach_func_proto = tgt_info.tgt_type; + prog->aux->attach_func_name = tgt_info.tgt_name; + + if (tgt_prog) { + prog->aux->saved_dst_prog_type = tgt_prog->type; + prog->aux->saved_dst_attach_type = tgt_prog->expected_attach_type; + } + + if (prog->expected_attach_type == BPF_TRACE_RAW_TP) { + prog->aux->attach_btf_trace = true; + return 0; + } else if (prog->expected_attach_type == BPF_TRACE_ITER) { + if (!bpf_iter_prog_supported(prog)) + return -EINVAL; + return 0; + } + + if (prog->type == BPF_PROG_TYPE_LSM) { + ret = bpf_lsm_verify_prog(&env->log, prog); + if (ret < 0) + return ret; + } else if (prog->type == BPF_PROG_TYPE_TRACING && + btf_id_set_contains(&btf_id_deny, btf_id)) { + return -EINVAL; + } + + key = bpf_trampoline_compute_key(tgt_prog, prog->aux->attach_btf, btf_id); + tr = bpf_trampoline_get(key, &tgt_info); + if (!tr) + return -ENOMEM; + + prog->aux->dst_trampoline = tr; + return 0; +} + +struct btf *bpf_get_btf_vmlinux(void) +{ + if (!btf_vmlinux && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) { + mutex_lock(&bpf_verifier_lock); + if (!btf_vmlinux) + btf_vmlinux = btf_parse_vmlinux(); + mutex_unlock(&bpf_verifier_lock); } + return btf_vmlinux; } -int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, - union bpf_attr __user *uattr) +int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr) { u64 start_time = ktime_get_ns(); struct bpf_verifier_env *env; @@ -10012,14 +15195,10 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, env->insn_aux_data[i].orig_idx = i; env->prog = *prog; env->ops = bpf_verifier_ops[env->prog->type]; - is_priv = capable(CAP_SYS_ADMIN); + env->fd_array = make_bpfptr(attr->fd_array, uattr.is_kernel); + is_priv = bpf_capable(); - if (!btf_vmlinux && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) { - mutex_lock(&bpf_verifier_lock); - if (!btf_vmlinux) - btf_vmlinux = btf_parse_vmlinux(); - mutex_unlock(&bpf_verifier_lock); - } + bpf_get_btf_vmlinux(); /* grab the mutex to protect few globals used by verifier */ if (!is_priv) @@ -10033,13 +15212,15 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, log->ubuf = (char __user *) (unsigned long) attr->log_buf; log->len_total = attr->log_size; - ret = -EINVAL; /* log attributes have to be sane */ - if (log->len_total < 128 || log->len_total > UINT_MAX >> 2 || - !log->level || !log->ubuf || log->level & ~BPF_LOG_MASK) + if (!bpf_verifier_log_attr_valid(log)) { + ret = -EINVAL; goto err_unlock; + } } + mark_verifier_state_clean(env); + if (IS_ERR(btf_vmlinux)) { /* Either gcc or pahole or kernel are broken. */ verbose(env, "in-kernel BTF is malformed\n"); @@ -10053,21 +15234,16 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, if (attr->prog_flags & BPF_F_ANY_ALIGNMENT) env->strict_alignment = false; - env->allow_ptr_leaks = is_priv; + env->allow_ptr_leaks = bpf_allow_ptr_leaks(); + env->allow_uninit_stack = bpf_allow_uninit_stack(); + env->allow_ptr_to_map_access = bpf_allow_ptr_to_map_access(); + env->bypass_spec_v1 = bpf_bypass_spec_v1(); + env->bypass_spec_v4 = bpf_bypass_spec_v4(); + env->bpf_capable = bpf_capable(); if (is_priv) env->test_state_freq = attr->prog_flags & BPF_F_TEST_STATE_FREQ; - ret = replace_map_fd_with_map_ptr(env); - if (ret < 0) - goto skip_full_check; - - if (bpf_prog_is_dev_bound(env->prog->aux)) { - ret = bpf_prog_offload_verifier_prep(env->prog); - if (ret) - goto skip_full_check; - } - env->explored_states = kvcalloc(state_htab_size(env), sizeof(struct bpf_verifier_state_list *), GFP_USER); @@ -10075,6 +15251,10 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, if (!env->explored_states) goto skip_full_check; + ret = add_subprog_and_kfunc(env); + if (ret < 0) + goto skip_full_check; + ret = check_subprogs(env); if (ret < 0) goto skip_full_check; @@ -10087,6 +15267,16 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, if (ret) goto skip_full_check; + ret = resolve_pseudo_ldimm64(env); + if (ret < 0) + goto skip_full_check; + + if (bpf_prog_is_dev_bound(env->prog->aux)) { + ret = bpf_prog_offload_verifier_prep(env->prog); + if (ret) + goto skip_full_check; + } + ret = check_cfg(env); if (ret < 0) goto skip_full_check; @@ -10104,6 +15294,9 @@ skip_full_check: ret = check_max_stack_depth(env); /* instruction rewrites happen after this point */ + if (ret == 0) + ret = optimize_bpf_loop(env); + if (is_priv) { if (ret == 0) opt_hard_wire_dead_code_branches(env); @@ -10121,7 +15314,7 @@ skip_full_check: ret = convert_ctx_accesses(env); if (ret == 0) - ret = fixup_bpf_calls(env); + ret = do_misc_fixups(env); /* do 32-bit optimization after insn patching has done so those patched * insns could be handled correctly. @@ -10137,6 +15330,7 @@ skip_full_check: env->verification_time = ktime_get_ns() - start_time; print_verification_stats(env); + env->prog->aux->verified_insns = env->insn_processed; if (log->level && bpf_verifier_log_full(log)) ret = -ENOSPC; @@ -10145,7 +15339,10 @@ skip_full_check: goto err_release_maps; } - if (ret == 0 && env->used_map_cnt) { + if (ret) + goto err_release_maps; + + if (env->used_map_cnt) { /* if program passed verifier, update used_maps in bpf_prog_info */ env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt, sizeof(env->used_maps[0]), @@ -10159,15 +15356,29 @@ skip_full_check: memcpy(env->prog->aux->used_maps, env->used_maps, sizeof(env->used_maps[0]) * env->used_map_cnt); env->prog->aux->used_map_cnt = env->used_map_cnt; + } + if (env->used_btf_cnt) { + /* if program passed verifier, update used_btfs in bpf_prog_aux */ + env->prog->aux->used_btfs = kmalloc_array(env->used_btf_cnt, + sizeof(env->used_btfs[0]), + GFP_KERNEL); + if (!env->prog->aux->used_btfs) { + ret = -ENOMEM; + goto err_release_maps; + } + memcpy(env->prog->aux->used_btfs, env->used_btfs, + sizeof(env->used_btfs[0]) * env->used_btf_cnt); + env->prog->aux->used_btf_cnt = env->used_btf_cnt; + } + if (env->used_map_cnt || env->used_btf_cnt) { /* program is valid. Convert pseudo bpf_ld_imm64 into generic * bpf_ld_imm64 instructions */ convert_pseudo_ld_imm64(env); } - if (ret == 0) - adjust_btf_func(env); + adjust_btf_func(env); err_release_maps: if (!env->prog->aux->used_maps) @@ -10175,6 +15386,15 @@ err_release_maps: * them now. Otherwise free_used_maps() will release them. */ release_maps(env); + if (!env->prog->aux->used_btfs) + release_btfs(env); + + /* extension progs temporarily inherit the attach_type of their targets + for verification purposes, so set it back to zero before returning + */ + if (env->prog->type == BPF_PROG_TYPE_EXT) + env->prog->expected_attach_type = 0; + *prog = env->prog; err_unlock: if (!is_priv) |