diff options
Diffstat (limited to 'kernel/bpf/btf.c')
| -rw-r--r-- | kernel/bpf/btf.c | 2147 |
1 files changed, 1893 insertions, 254 deletions
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 9bdb03767db5..35c07afac924 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -1,4 +1,4 @@ -/* SPDX-License-Identifier: GPL-2.0 */ +// SPDX-License-Identifier: GPL-2.0 /* Copyright (c) 2018 Facebook */ #include <uapi/linux/btf.h> @@ -25,6 +25,7 @@ #include <linux/kobject.h> #include <linux/sysfs.h> #include <net/sock.h> +#include "../tools/lib/bpf/relo_core.h" /* BTF (BPF Type Format) is the meta data format which describes * the data types of BPF program/map. Hence, it basically focus @@ -197,6 +198,29 @@ DEFINE_IDR(btf_idr); DEFINE_SPINLOCK(btf_idr_lock); +enum btf_kfunc_hook { + BTF_KFUNC_HOOK_XDP, + BTF_KFUNC_HOOK_TC, + BTF_KFUNC_HOOK_STRUCT_OPS, + BTF_KFUNC_HOOK_TRACING, + BTF_KFUNC_HOOK_SYSCALL, + BTF_KFUNC_HOOK_MAX, +}; + +enum { + BTF_KFUNC_SET_MAX_CNT = 256, + BTF_DTOR_KFUNC_MAX_CNT = 256, +}; + +struct btf_kfunc_set_tab { + struct btf_id_set8 *sets[BTF_KFUNC_HOOK_MAX]; +}; + +struct btf_id_dtor_kfunc_tab { + u32 cnt; + struct btf_id_dtor_kfunc dtors[]; +}; + struct btf { void *data; struct btf_type **types; @@ -211,6 +235,8 @@ struct btf { refcount_t refcnt; u32 id; struct rcu_head rcu; + struct btf_kfunc_set_tab *kfunc_set_tab; + struct btf_id_dtor_kfunc_tab *dtor_kfunc_tab; /* split BTF support */ struct btf *base_btf; @@ -282,6 +308,8 @@ static const char * const btf_kind_str[NR_BTF_KINDS] = { [BTF_KIND_DATASEC] = "DATASEC", [BTF_KIND_FLOAT] = "FLOAT", [BTF_KIND_DECL_TAG] = "DECL_TAG", + [BTF_KIND_TYPE_TAG] = "TYPE_TAG", + [BTF_KIND_ENUM64] = "ENUM64", }; const char *btf_type_str(const struct btf_type *t) @@ -401,6 +429,9 @@ static struct btf_type btf_void; static int btf_resolve(struct btf_verifier_env *env, const struct btf_type *t, u32 type_id); +static int btf_func_check(struct btf_verifier_env *env, + const struct btf_type *t); + static bool btf_type_is_modifier(const struct btf_type *t) { /* Some of them is not strictly a C modifier @@ -418,6 +449,7 @@ static bool btf_type_is_modifier(const struct btf_type *t) case BTF_KIND_VOLATILE: case BTF_KIND_CONST: case BTF_KIND_RESTRICT: + case BTF_KIND_TYPE_TAG: return true; } @@ -503,6 +535,50 @@ s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind) return -ENOENT; } +static s32 bpf_find_btf_id(const char *name, u32 kind, struct btf **btf_p) +{ + struct btf *btf; + s32 ret; + int id; + + btf = bpf_get_btf_vmlinux(); + if (IS_ERR(btf)) + return PTR_ERR(btf); + if (!btf) + return -EINVAL; + + ret = btf_find_by_name_kind(btf, name, kind); + /* ret is never zero, since btf_find_by_name_kind returns + * positive btf_id or negative error. + */ + if (ret > 0) { + btf_get(btf); + *btf_p = btf; + return ret; + } + + /* If name is not found in vmlinux's BTF then search in module's BTFs */ + spin_lock_bh(&btf_idr_lock); + idr_for_each_entry(&btf_idr, btf, id) { + if (!btf_is_module(btf)) + continue; + /* linear search could be slow hence unlock/lock + * the IDR to avoiding holding it for too long + */ + btf_get(btf); + spin_unlock_bh(&btf_idr_lock); + ret = btf_find_by_name_kind(btf, name, kind); + if (ret > 0) { + *btf_p = btf; + return ret; + } + spin_lock_bh(&btf_idr_lock); + btf_put(btf); + } + spin_unlock_bh(&btf_idr_lock); + return ret; +} + const struct btf_type *btf_type_skip_modifiers(const struct btf *btf, u32 id, u32 *res_id) { @@ -576,6 +652,7 @@ static bool btf_type_needs_resolve(const struct btf_type *t) btf_type_is_struct(t) || btf_type_is_array(t) || btf_type_is_var(t) || + btf_type_is_func(t) || btf_type_is_decl_tag(t) || btf_type_is_datasec(t); } @@ -590,6 +667,7 @@ static bool btf_type_has_size(const struct btf_type *t) case BTF_KIND_ENUM: case BTF_KIND_DATASEC: case BTF_KIND_FLOAT: + case BTF_KIND_ENUM64: return true; } @@ -635,6 +713,11 @@ static const struct btf_decl_tag *btf_type_decl_tag(const struct btf_type *t) return (const struct btf_decl_tag *)(t + 1); } +static const struct btf_enum64 *btf_type_enum64(const struct btf_type *t) +{ + return (const struct btf_enum64 *)(t + 1); +} + static const struct btf_kind_operations *btf_type_ops(const struct btf_type *t) { return kind_ops[BTF_INFO_KIND(t->info)]; @@ -735,6 +818,7 @@ const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id) return NULL; return btf->types[type_id]; } +EXPORT_SYMBOL_GPL(btf_type_by_id); /* * Regular int is not a bit field and it must be either @@ -834,7 +918,7 @@ static const char *btf_show_name(struct btf_show *show) const char *ptr_suffix = &ptr_suffixes[strlen(ptr_suffixes)]; const char *name = NULL, *prefix = "", *parens = ""; const struct btf_member *m = show->state.member; - const struct btf_type *t = show->state.type; + const struct btf_type *t; const struct btf_array *array; u32 id = show->state.type_id; const char *member = NULL; @@ -943,6 +1027,7 @@ static const char *btf_show_name(struct btf_show *show) parens = "{"; break; case BTF_KIND_ENUM: + case BTF_KIND_ENUM64: prefix = "enum"; break; default: @@ -1032,7 +1117,8 @@ __printf(2, 3) static void btf_show(struct btf_show *show, const char *fmt, ...) */ #define btf_show_type_value(show, fmt, value) \ do { \ - if ((value) != 0 || (show->flags & BTF_SHOW_ZERO) || \ + if ((value) != (__typeof__(value))0 || \ + (show->flags & BTF_SHOW_ZERO) || \ show->state.depth == 0) { \ btf_show(show, "%s%s" fmt "%s%s", \ btf_show_indent(show), \ @@ -1311,7 +1397,6 @@ __printf(4, 5) static void __btf_verifier_log_type(struct btf_verifier_env *env, const char *fmt, ...) { struct bpf_verifier_log *log = &env->log; - u8 kind = BTF_INFO_KIND(t->info); struct btf *btf = env->btf; va_list args; @@ -1327,7 +1412,7 @@ __printf(4, 5) static void __btf_verifier_log_type(struct btf_verifier_env *env, __btf_verifier_log(log, "[%u] %s %s%s", env->log_type_id, - btf_kind_str[kind], + btf_type_str(t), __btf_name_by_offset(btf, t->name_off), log_details ? " " : ""); @@ -1528,8 +1613,39 @@ static void btf_free_id(struct btf *btf) spin_unlock_irqrestore(&btf_idr_lock, flags); } +static void btf_free_kfunc_set_tab(struct btf *btf) +{ + struct btf_kfunc_set_tab *tab = btf->kfunc_set_tab; + int hook; + + if (!tab) + return; + /* For module BTF, we directly assign the sets being registered, so + * there is nothing to free except kfunc_set_tab. + */ + if (btf_is_module(btf)) + goto free_tab; + for (hook = 0; hook < ARRAY_SIZE(tab->sets); hook++) + kfree(tab->sets[hook]); +free_tab: + kfree(tab); + btf->kfunc_set_tab = NULL; +} + +static void btf_free_dtor_kfunc_tab(struct btf *btf) +{ + struct btf_id_dtor_kfunc_tab *tab = btf->dtor_kfunc_tab; + + if (!tab) + return; + kfree(tab); + btf->dtor_kfunc_tab = NULL; +} + static void btf_free(struct btf *btf) { + btf_free_dtor_kfunc_tab(btf); + btf_free_kfunc_set_tab(btf); kvfree(btf->types); kvfree(btf->resolved_sizes); kvfree(btf->resolved_ids); @@ -1725,6 +1841,7 @@ __btf_resolve_size(const struct btf *btf, const struct btf_type *type, case BTF_KIND_UNION: case BTF_KIND_ENUM: case BTF_KIND_FLOAT: + case BTF_KIND_ENUM64: size = type->size; goto resolved; @@ -1737,6 +1854,7 @@ __btf_resolve_size(const struct btf *btf, const struct btf_type *type, case BTF_KIND_VOLATILE: case BTF_KIND_CONST: case BTF_KIND_RESTRICT: + case BTF_KIND_TYPE_TAG: id = type->type; type = btf_type_by_id(btf, type->type); break; @@ -2345,6 +2463,8 @@ static int btf_ref_type_check_meta(struct btf_verifier_env *env, const struct btf_type *t, u32 meta_left) { + const char *value; + if (btf_type_vlen(t)) { btf_verifier_log_type(env, t, "vlen != 0"); return -EINVAL; @@ -2360,7 +2480,7 @@ static int btf_ref_type_check_meta(struct btf_verifier_env *env, return -EINVAL; } - /* typedef type must have a valid name, and other ref types, + /* typedef/type_tag type must have a valid name, and other ref types, * volatile, const, restrict, should have a null name. */ if (BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF) { @@ -2369,6 +2489,12 @@ static int btf_ref_type_check_meta(struct btf_verifier_env *env, btf_verifier_log_type(env, t, "Invalid name"); return -EINVAL; } + } else if (BTF_INFO_KIND(t->info) == BTF_KIND_TYPE_TAG) { + value = btf_name_by_offset(env->btf, t->name_off); + if (!value || !value[0]) { + btf_verifier_log_type(env, t, "Invalid name"); + return -EINVAL; + } } else { if (t->name_off) { btf_verifier_log_type(env, t, "Invalid name"); @@ -2493,7 +2619,7 @@ static int btf_ptr_resolve(struct btf_verifier_env *env, * * We now need to continue from the last-resolved-ptr to * ensure the last-resolved-ptr will not referring back to - * the currenct ptr (t). + * the current ptr (t). */ if (btf_type_is_modifier(next_type)) { const struct btf_type *resolved_type; @@ -2958,7 +3084,7 @@ static s32 btf_struct_check_meta(struct btf_verifier_env *env, return -EINVAL; } - offset = btf_member_bit_offset(t, member); + offset = __btf_member_bit_offset(t, member); if (is_union && offset) { btf_verifier_log_member(env, t, member, "Invalid member bits_offset"); @@ -3002,7 +3128,7 @@ static int btf_struct_resolve(struct btf_verifier_env *env, if (v->next_member) { const struct btf_type *last_member_type; const struct btf_member *last_member; - u16 last_member_type_id; + u32 last_member_type_id; last_member = btf_type_member(v->t) + v->next_member - 1; last_member_type_id = last_member->type; @@ -3065,71 +3191,202 @@ static void btf_struct_log(struct btf_verifier_env *env, btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t)); } +enum btf_field_type { + BTF_FIELD_SPIN_LOCK, + BTF_FIELD_TIMER, + BTF_FIELD_KPTR, +}; + +enum { + BTF_FIELD_IGNORE = 0, + BTF_FIELD_FOUND = 1, +}; + +struct btf_field_info { + u32 type_id; + u32 off; + enum bpf_kptr_type type; +}; + +static int btf_find_struct(const struct btf *btf, const struct btf_type *t, + u32 off, int sz, struct btf_field_info *info) +{ + if (!__btf_type_is_struct(t)) + return BTF_FIELD_IGNORE; + if (t->size != sz) + return BTF_FIELD_IGNORE; + info->off = off; + return BTF_FIELD_FOUND; +} + +static int btf_find_kptr(const struct btf *btf, const struct btf_type *t, + u32 off, int sz, struct btf_field_info *info) +{ + enum bpf_kptr_type type; + u32 res_id; + + /* For PTR, sz is always == 8 */ + if (!btf_type_is_ptr(t)) + return BTF_FIELD_IGNORE; + t = btf_type_by_id(btf, t->type); + + if (!btf_type_is_type_tag(t)) + return BTF_FIELD_IGNORE; + /* Reject extra tags */ + if (btf_type_is_type_tag(btf_type_by_id(btf, t->type))) + return -EINVAL; + if (!strcmp("kptr", __btf_name_by_offset(btf, t->name_off))) + type = BPF_KPTR_UNREF; + else if (!strcmp("kptr_ref", __btf_name_by_offset(btf, t->name_off))) + type = BPF_KPTR_REF; + else + return -EINVAL; + + /* Get the base type */ + t = btf_type_skip_modifiers(btf, t->type, &res_id); + /* Only pointer to struct is allowed */ + if (!__btf_type_is_struct(t)) + return -EINVAL; + + info->type_id = res_id; + info->off = off; + info->type = type; + return BTF_FIELD_FOUND; +} + static int btf_find_struct_field(const struct btf *btf, const struct btf_type *t, - const char *name, int sz, int align) + const char *name, int sz, int align, + enum btf_field_type field_type, + struct btf_field_info *info, int info_cnt) { const struct btf_member *member; - u32 i, off = -ENOENT; + struct btf_field_info tmp; + int ret, idx = 0; + u32 i, off; for_each_member(i, t, member) { const struct btf_type *member_type = btf_type_by_id(btf, member->type); - if (!__btf_type_is_struct(member_type)) - continue; - if (member_type->size != sz) - continue; - if (strcmp(__btf_name_by_offset(btf, member_type->name_off), name)) + + if (name && strcmp(__btf_name_by_offset(btf, member_type->name_off), name)) continue; - if (off != -ENOENT) - /* only one such field is allowed */ - return -E2BIG; - off = btf_member_bit_offset(t, member); + + off = __btf_member_bit_offset(t, member); if (off % 8) /* valid C code cannot generate such BTF */ return -EINVAL; off /= 8; if (off % align) return -EINVAL; + + switch (field_type) { + case BTF_FIELD_SPIN_LOCK: + case BTF_FIELD_TIMER: + ret = btf_find_struct(btf, member_type, off, sz, + idx < info_cnt ? &info[idx] : &tmp); + if (ret < 0) + return ret; + break; + case BTF_FIELD_KPTR: + ret = btf_find_kptr(btf, member_type, off, sz, + idx < info_cnt ? &info[idx] : &tmp); + if (ret < 0) + return ret; + break; + default: + return -EFAULT; + } + + if (ret == BTF_FIELD_IGNORE) + continue; + if (idx >= info_cnt) + return -E2BIG; + ++idx; } - return off; + return idx; } static int btf_find_datasec_var(const struct btf *btf, const struct btf_type *t, - const char *name, int sz, int align) + const char *name, int sz, int align, + enum btf_field_type field_type, + struct btf_field_info *info, int info_cnt) { const struct btf_var_secinfo *vsi; - u32 i, off = -ENOENT; + struct btf_field_info tmp; + int ret, idx = 0; + u32 i, off; for_each_vsi(i, t, vsi) { const struct btf_type *var = btf_type_by_id(btf, vsi->type); const struct btf_type *var_type = btf_type_by_id(btf, var->type); - if (!__btf_type_is_struct(var_type)) - continue; - if (var_type->size != sz) + off = vsi->offset; + + if (name && strcmp(__btf_name_by_offset(btf, var_type->name_off), name)) continue; if (vsi->size != sz) continue; - if (strcmp(__btf_name_by_offset(btf, var_type->name_off), name)) - continue; - if (off != -ENOENT) - /* only one such field is allowed */ - return -E2BIG; - off = vsi->offset; if (off % align) return -EINVAL; + + switch (field_type) { + case BTF_FIELD_SPIN_LOCK: + case BTF_FIELD_TIMER: + ret = btf_find_struct(btf, var_type, off, sz, + idx < info_cnt ? &info[idx] : &tmp); + if (ret < 0) + return ret; + break; + case BTF_FIELD_KPTR: + ret = btf_find_kptr(btf, var_type, off, sz, + idx < info_cnt ? &info[idx] : &tmp); + if (ret < 0) + return ret; + break; + default: + return -EFAULT; + } + + if (ret == BTF_FIELD_IGNORE) + continue; + if (idx >= info_cnt) + return -E2BIG; + ++idx; } - return off; + return idx; } static int btf_find_field(const struct btf *btf, const struct btf_type *t, - const char *name, int sz, int align) + enum btf_field_type field_type, + struct btf_field_info *info, int info_cnt) { + const char *name; + int sz, align; + + switch (field_type) { + case BTF_FIELD_SPIN_LOCK: + name = "bpf_spin_lock"; + sz = sizeof(struct bpf_spin_lock); + align = __alignof__(struct bpf_spin_lock); + break; + case BTF_FIELD_TIMER: + name = "bpf_timer"; + sz = sizeof(struct bpf_timer); + align = __alignof__(struct bpf_timer); + break; + case BTF_FIELD_KPTR: + name = NULL; + sz = sizeof(u64); + align = 8; + break; + default: + return -EFAULT; + } if (__btf_type_is_struct(t)) - return btf_find_struct_field(btf, t, name, sz, align); + return btf_find_struct_field(btf, t, name, sz, align, field_type, info, info_cnt); else if (btf_type_is_datasec(t)) - return btf_find_datasec_var(btf, t, name, sz, align); + return btf_find_datasec_var(btf, t, name, sz, align, field_type, info, info_cnt); return -EINVAL; } @@ -3139,16 +3396,130 @@ static int btf_find_field(const struct btf *btf, const struct btf_type *t, */ int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t) { - return btf_find_field(btf, t, "bpf_spin_lock", - sizeof(struct bpf_spin_lock), - __alignof__(struct bpf_spin_lock)); + struct btf_field_info info; + int ret; + + ret = btf_find_field(btf, t, BTF_FIELD_SPIN_LOCK, &info, 1); + if (ret < 0) + return ret; + if (!ret) + return -ENOENT; + return info.off; } int btf_find_timer(const struct btf *btf, const struct btf_type *t) { - return btf_find_field(btf, t, "bpf_timer", - sizeof(struct bpf_timer), - __alignof__(struct bpf_timer)); + struct btf_field_info info; + int ret; + + ret = btf_find_field(btf, t, BTF_FIELD_TIMER, &info, 1); + if (ret < 0) + return ret; + if (!ret) + return -ENOENT; + return info.off; +} + +struct bpf_map_value_off *btf_parse_kptrs(const struct btf *btf, + const struct btf_type *t) +{ + struct btf_field_info info_arr[BPF_MAP_VALUE_OFF_MAX]; + struct bpf_map_value_off *tab; + struct btf *kernel_btf = NULL; + struct module *mod = NULL; + int ret, i, nr_off; + + ret = btf_find_field(btf, t, BTF_FIELD_KPTR, info_arr, ARRAY_SIZE(info_arr)); + if (ret < 0) + return ERR_PTR(ret); + if (!ret) + return NULL; + + nr_off = ret; + tab = kzalloc(offsetof(struct bpf_map_value_off, off[nr_off]), GFP_KERNEL | __GFP_NOWARN); + if (!tab) + return ERR_PTR(-ENOMEM); + + for (i = 0; i < nr_off; i++) { + const struct btf_type *t; + s32 id; + + /* Find type in map BTF, and use it to look up the matching type + * in vmlinux or module BTFs, by name and kind. + */ + t = btf_type_by_id(btf, info_arr[i].type_id); + id = bpf_find_btf_id(__btf_name_by_offset(btf, t->name_off), BTF_INFO_KIND(t->info), + &kernel_btf); + if (id < 0) { + ret = id; + goto end; + } + + /* Find and stash the function pointer for the destruction function that + * needs to be eventually invoked from the map free path. + */ + if (info_arr[i].type == BPF_KPTR_REF) { + const struct btf_type *dtor_func; + const char *dtor_func_name; + unsigned long addr; + s32 dtor_btf_id; + + /* This call also serves as a whitelist of allowed objects that + * can be used as a referenced pointer and be stored in a map at + * the same time. + */ + dtor_btf_id = btf_find_dtor_kfunc(kernel_btf, id); + if (dtor_btf_id < 0) { + ret = dtor_btf_id; + goto end_btf; + } + + dtor_func = btf_type_by_id(kernel_btf, dtor_btf_id); + if (!dtor_func) { + ret = -ENOENT; + goto end_btf; + } + + if (btf_is_module(kernel_btf)) { + mod = btf_try_get_module(kernel_btf); + if (!mod) { + ret = -ENXIO; + goto end_btf; + } + } + + /* We already verified dtor_func to be btf_type_is_func + * in register_btf_id_dtor_kfuncs. + */ + dtor_func_name = __btf_name_by_offset(kernel_btf, dtor_func->name_off); + addr = kallsyms_lookup_name(dtor_func_name); + if (!addr) { + ret = -EINVAL; + goto end_mod; + } + tab->off[i].kptr.dtor = (void *)addr; + } + + tab->off[i].offset = info_arr[i].off; + tab->off[i].type = info_arr[i].type; + tab->off[i].kptr.btf_id = id; + tab->off[i].kptr.btf = kernel_btf; + tab->off[i].kptr.module = mod; + } + tab->nr_off = nr_off; + return tab; +end_mod: + module_put(mod); +end_btf: + btf_put(kernel_btf); +end: + while (i--) { + btf_put(tab->off[i].kptr.btf); + if (tab->off[i].kptr.module) + module_put(tab->off[i].kptr.module); + } + kfree(tab); + return ERR_PTR(ret); } static void __btf_struct_show(const struct btf *btf, const struct btf_type *t, @@ -3173,8 +3544,8 @@ static void __btf_struct_show(const struct btf *btf, const struct btf_type *t, btf_show_start_member(show, member); - member_offset = btf_member_bit_offset(t, member); - bitfield_size = btf_member_bitfield_size(t, member); + member_offset = __btf_member_bit_offset(t, member); + bitfield_size = __btf_member_bitfield_size(t, member); bytes_offset = BITS_ROUNDDOWN_BYTES(member_offset); bits8_offset = BITS_PER_BYTE_MASKED(member_offset); if (bitfield_size) { @@ -3307,6 +3678,7 @@ static s32 btf_enum_check_meta(struct btf_verifier_env *env, { const struct btf_enum *enums = btf_type_enum(t); struct btf *btf = env->btf; + const char *fmt_str; u16 i, nr_enums; u32 meta_needed; @@ -3320,11 +3692,6 @@ static s32 btf_enum_check_meta(struct btf_verifier_env *env, return -EINVAL; } - if (btf_type_kflag(t)) { - btf_verifier_log_type(env, t, "Invalid btf_info kind_flag"); - return -EINVAL; - } - if (t->size > 8 || !is_power_of_2(t->size)) { btf_verifier_log_type(env, t, "Unexpected size"); return -EINVAL; @@ -3355,7 +3722,8 @@ static s32 btf_enum_check_meta(struct btf_verifier_env *env, if (env->log.level == BPF_LOG_KERNEL) continue; - btf_verifier_log(env, "\t%s val=%d\n", + fmt_str = btf_type_kflag(t) ? "\t%s val=%d\n" : "\t%s val=%u\n"; + btf_verifier_log(env, fmt_str, __btf_name_by_offset(btf, enums[i].name_off), enums[i].val); } @@ -3396,7 +3764,10 @@ static void btf_enum_show(const struct btf *btf, const struct btf_type *t, return; } - btf_show_type_value(show, "%d", v); + if (btf_type_kflag(t)) + btf_show_type_value(show, "%d", v); + else + btf_show_type_value(show, "%u", v); btf_show_end_type(show); } @@ -3409,6 +3780,109 @@ static struct btf_kind_operations enum_ops = { .show = btf_enum_show, }; +static s32 btf_enum64_check_meta(struct btf_verifier_env *env, + const struct btf_type *t, + u32 meta_left) +{ + const struct btf_enum64 *enums = btf_type_enum64(t); + struct btf *btf = env->btf; + const char *fmt_str; + u16 i, nr_enums; + u32 meta_needed; + + nr_enums = btf_type_vlen(t); + meta_needed = nr_enums * sizeof(*enums); + + if (meta_left < meta_needed) { + btf_verifier_log_basic(env, t, + "meta_left:%u meta_needed:%u", + meta_left, meta_needed); + return -EINVAL; + } + + if (t->size > 8 || !is_power_of_2(t->size)) { + btf_verifier_log_type(env, t, "Unexpected size"); + return -EINVAL; + } + + /* enum type either no name or a valid one */ + if (t->name_off && + !btf_name_valid_identifier(env->btf, t->name_off)) { + btf_verifier_log_type(env, t, "Invalid name"); + return -EINVAL; + } + + btf_verifier_log_type(env, t, NULL); + + for (i = 0; i < nr_enums; i++) { + if (!btf_name_offset_valid(btf, enums[i].name_off)) { + btf_verifier_log(env, "\tInvalid name_offset:%u", + enums[i].name_off); + return -EINVAL; + } + + /* enum member must have a valid name */ + if (!enums[i].name_off || + !btf_name_valid_identifier(btf, enums[i].name_off)) { + btf_verifier_log_type(env, t, "Invalid name"); + return -EINVAL; + } + + if (env->log.level == BPF_LOG_KERNEL) + continue; + + fmt_str = btf_type_kflag(t) ? "\t%s val=%lld\n" : "\t%s val=%llu\n"; + btf_verifier_log(env, fmt_str, + __btf_name_by_offset(btf, enums[i].name_off), + btf_enum64_value(enums + i)); + } + + return meta_needed; +} + +static void btf_enum64_show(const struct btf *btf, const struct btf_type *t, + u32 type_id, void *data, u8 bits_offset, + struct btf_show *show) +{ + const struct btf_enum64 *enums = btf_type_enum64(t); + u32 i, nr_enums = btf_type_vlen(t); + void *safe_data; + s64 v; + + safe_data = btf_show_start_type(show, t, type_id, data); + if (!safe_data) + return; + + v = *(u64 *)safe_data; + + for (i = 0; i < nr_enums; i++) { + if (v != btf_enum64_value(enums + i)) + continue; + + btf_show_type_value(show, "%s", + __btf_name_by_offset(btf, + enums[i].name_off)); + + btf_show_end_type(show); + return; + } + + if (btf_type_kflag(t)) + btf_show_type_value(show, "%lld", v); + else + btf_show_type_value(show, "%llu", v); + btf_show_end_type(show); +} + +static struct btf_kind_operations enum64_ops = { + .check_meta = btf_enum64_check_meta, + .resolve = btf_df_resolve, + .check_member = btf_enum_check_member, + .check_kflag_member = btf_enum_check_kflag_member, + .log_details = btf_enum_log, + .show = btf_enum64_show, +}; + static s32 btf_func_proto_check_meta(struct btf_verifier_env *env, const struct btf_type *t, u32 meta_left) @@ -3521,9 +3995,24 @@ static s32 btf_func_check_meta(struct btf_verifier_env *env, return 0; } +static int btf_func_resolve(struct btf_verifier_env *env, + const struct resolve_vertex *v) +{ + const struct btf_type *t = v->t; + u32 next_type_id = t->type; + int err; + + err = btf_func_check(env, t); + if (err) + return err; + + env_stack_pop_resolved(env, next_type_id, 0); + return 0; +} + static struct btf_kind_operations func_ops = { .check_meta = btf_func_check_meta, - .resolve = btf_df_resolve, + .resolve = btf_func_resolve, .check_member = btf_df_check_member, .check_kflag_member = btf_df_check_kflag_member, .log_details = btf_ref_type_log, @@ -3947,6 +4436,11 @@ static int btf_func_proto_check(struct btf_verifier_env *env, return -EINVAL; } + if (btf_type_is_resolve_source_only(ret_type)) { + btf_verifier_log_type(env, t, "Invalid return type"); + return -EINVAL; + } + if (btf_type_needs_resolve(ret_type) && !env_type_is_resolved(env, ret_type_id)) { err = btf_resolve(env, ret_type, ret_type_id); @@ -4059,6 +4553,8 @@ static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS] = { [BTF_KIND_DATASEC] = &datasec_ops, [BTF_KIND_FLOAT] = &float_ops, [BTF_KIND_DECL_TAG] = &decl_tag_ops, + [BTF_KIND_TYPE_TAG] = &modifier_ops, + [BTF_KIND_ENUM64] = &enum64_ops, }; static s32 btf_check_meta(struct btf_verifier_env *env, @@ -4143,7 +4639,7 @@ static bool btf_resolve_valid(struct btf_verifier_env *env, return !btf_resolved_type_id(btf, type_id) && !btf_resolved_type_size(btf, type_id); - if (btf_type_is_decl_tag(t)) + if (btf_type_is_decl_tag(t) || btf_type_is_func(t)) return btf_resolved_type_id(btf, type_id) && !btf_resolved_type_size(btf, type_id); @@ -4233,12 +4729,6 @@ static int btf_check_all_types(struct btf_verifier_env *env) if (err) return err; } - - if (btf_type_is_func(t)) { - err = btf_func_check(env, t); - if (err) - return err; - } } return 0; @@ -4369,13 +4859,11 @@ static int btf_parse_hdr(struct btf_verifier_env *env) u32 hdr_len, hdr_copy, btf_data_size; const struct btf_header *hdr; struct btf *btf; - int err; btf = env->btf; btf_data_size = btf->data_size; - if (btf_data_size < - offsetof(struct btf_header, hdr_len) + sizeof(hdr->hdr_len)) { + if (btf_data_size < offsetofend(struct btf_header, hdr_len)) { btf_verifier_log(env, "hdr_len not found"); return -EINVAL; } @@ -4427,10 +4915,53 @@ static int btf_parse_hdr(struct btf_verifier_env *env) return -EINVAL; } - err = btf_check_sec_info(env, btf_data_size); - if (err) - return err; + return btf_check_sec_info(env, btf_data_size); +} + +static int btf_check_type_tags(struct btf_verifier_env *env, + struct btf *btf, int start_id) +{ + int i, n, good_id = start_id - 1; + bool in_tags; + + n = btf_nr_types(btf); + for (i = start_id; i < n; i++) { + const struct btf_type *t; + int chain_limit = 32; + u32 cur_id = i; + t = btf_type_by_id(btf, i); + if (!t) + return -EINVAL; + if (!btf_type_is_modifier(t)) + continue; + + cond_resched(); + + in_tags = btf_type_is_type_tag(t); + while (btf_type_is_modifier(t)) { + if (!chain_limit--) { + btf_verifier_log(env, "Max chain length or cycle detected"); + return -ELOOP; + } + if (btf_type_is_type_tag(t)) { + if (!in_tags) { + btf_verifier_log(env, "Type tags don't precede modifiers"); + return -EINVAL; + } + } else if (in_tags) { + in_tags = false; + } + if (cur_id <= good_id) + break; + /* Move to next type */ + cur_id = t->type; + t = btf_type_by_id(btf, cur_id); + if (!t) + return -EINVAL; + } + good_id = i; + } return 0; } @@ -4460,8 +4991,7 @@ static struct btf *btf_parse(bpfptr_t btf_data, u32 btf_data_size, log->len_total = log_size; /* log attributes have to be sane */ - if (log->len_total < 128 || log->len_total > UINT_MAX >> 8 || - !log->level || !log->ubuf) { + if (!bpf_verifier_log_attr_valid(log)) { err = -EINVAL; goto errout; } @@ -4502,6 +5032,10 @@ static struct btf *btf_parse(bpfptr_t btf_data, u32 btf_data_size, if (err) goto errout; + err = btf_check_type_tags(env, btf, 1); + if (err) + goto errout; + if (log->level && bpf_verifier_log_full(log)) { err = -ENOSPC; goto errout; @@ -4610,41 +5144,6 @@ btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf, return ctx_type; } -static const struct bpf_map_ops * const btf_vmlinux_map_ops[] = { -#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) -#define BPF_LINK_TYPE(_id, _name) -#define BPF_MAP_TYPE(_id, _ops) \ - [_id] = &_ops, -#include <linux/bpf_types.h> -#undef BPF_PROG_TYPE -#undef BPF_LINK_TYPE -#undef BPF_MAP_TYPE -}; - -static int btf_vmlinux_map_ids_init(const struct btf *btf, - struct bpf_verifier_log *log) -{ - const struct bpf_map_ops *ops; - int i, btf_id; - - for (i = 0; i < ARRAY_SIZE(btf_vmlinux_map_ops); ++i) { - ops = btf_vmlinux_map_ops[i]; - if (!ops || (!ops->map_btf_name && !ops->map_btf_id)) - continue; - if (!ops->map_btf_name || !ops->map_btf_id) { - bpf_log(log, "map type %d is misconfigured\n", i); - return -EINVAL; - } - btf_id = btf_find_by_name_kind(btf, ops->map_btf_name, - BTF_KIND_STRUCT); - if (btf_id < 0) - return btf_id; - *ops->map_btf_id = btf_id; - } - - return 0; -} - static int btf_translate_to_vmlinux(struct bpf_verifier_log *log, struct btf *btf, const struct btf_type *t, @@ -4703,14 +5202,13 @@ struct btf *btf_parse_vmlinux(void) if (err) goto errout; + err = btf_check_type_tags(env, btf, 1); + if (err) + goto errout; + /* btf_parse_vmlinux() runs under bpf_verifier_lock */ bpf_ctx_convert.t = btf_type_by_id(btf, bpf_ctx_convert_btf_id[0]); - /* find bpf map structs for map_ptr access checking */ - err = btf_vmlinux_map_ids_init(btf, log); - if (err < 0) - goto errout; - bpf_struct_ops_init(btf, log); refcount_set(&btf->refcnt, 1); @@ -4788,6 +5286,10 @@ static struct btf *btf_parse_module(const char *module_name, const void *data, u if (err) goto errout; + err = btf_check_type_tags(env, btf, btf_nr_types(base_btf)); + if (err) + goto errout; + btf_verifier_env_free(env); refcount_set(&btf->refcnt, 1); return btf; @@ -4814,7 +5316,7 @@ struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog) return prog->aux->attach_btf; } -static bool is_string_ptr(struct btf *btf, const struct btf_type *t) +static bool is_int_ptr(struct btf *btf, const struct btf_type *t) { /* t comes in already as a pointer */ t = btf_type_by_id(btf, t->type); @@ -4823,8 +5325,35 @@ static bool is_string_ptr(struct btf *btf, const struct btf_type *t) if (BTF_INFO_KIND(t->info) == BTF_KIND_CONST) t = btf_type_by_id(btf, t->type); - /* char, signed char, unsigned char */ - return btf_type_is_int(t) && t->size == 1; + return btf_type_is_int(t); +} + +static u32 get_ctx_arg_idx(struct btf *btf, const struct btf_type *func_proto, + int off) +{ + const struct btf_param *args; + const struct btf_type *t; + u32 offset = 0, nr_args; + int i; + + if (!func_proto) + return off / 8; + + nr_args = btf_type_vlen(func_proto); + args = (const struct btf_param *)(func_proto + 1); + for (i = 0; i < nr_args; i++) { + t = btf_type_skip_modifiers(btf, args[i].type, NULL); + offset += btf_type_is_ptr(t) ? 8 : roundup(t->size, 8); + if (off < offset) + return i; + } + + t = btf_type_skip_modifiers(btf, func_proto->type, NULL); + offset += btf_type_is_ptr(t) ? 8 : roundup(t->size, 8); + if (off < offset) + return nr_args; + + return nr_args + 1; } bool btf_ctx_access(int off, int size, enum bpf_access_type type, @@ -4837,6 +5366,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, const char *tname = prog->aux->attach_func_name; struct bpf_verifier_log *log = info->log; const struct btf_param *args; + const char *tag_value; u32 nr_args, arg; int i, ret; @@ -4845,7 +5375,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, tname, off); return false; } - arg = off / 8; + arg = get_ctx_arg_idx(btf, t, off); args = (const struct btf_param *)(t + 1); /* if (t == NULL) Fall back to default BPF prog with * MAX_BPF_FUNC_REG_ARGS u64 arguments. @@ -4865,6 +5395,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, if (arg == nr_args) { switch (prog->expected_attach_type) { + case BPF_LSM_CGROUP: case BPF_LSM_MAC: case BPF_TRACE_FEXIT: /* When LSM programs are attached to void LSM hooks @@ -4895,7 +5426,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, if (!btf_type_is_small_int(t)) { bpf_log(log, "ret type %s not allowed for fmod_ret\n", - btf_kind_str[BTF_INFO_KIND(t->info)]); + btf_type_str(t)); return false; } break; @@ -4914,7 +5445,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, /* skip modifiers */ while (btf_type_is_modifier(t)) t = btf_type_by_id(btf, t->type); - if (btf_type_is_small_int(t) || btf_type_is_enum(t)) + if (btf_type_is_small_int(t) || btf_is_any_enum(t) || __btf_type_is_struct(t)) /* accessing a scalar */ return true; if (!btf_type_is_ptr(t)) { @@ -4922,17 +5453,19 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, "func '%s' arg%d '%s' has type %s. Only pointer access is allowed\n", tname, arg, __btf_name_by_offset(btf, t->name_off), - btf_kind_str[BTF_INFO_KIND(t->info)]); + btf_type_str(t)); return false; } /* check for PTR_TO_RDONLY_BUF_OR_NULL or PTR_TO_RDWR_BUF_OR_NULL */ for (i = 0; i < prog->aux->ctx_arg_info_size; i++) { const struct bpf_ctx_arg_aux *ctx_arg_info = &prog->aux->ctx_arg_info[i]; + u32 type, flag; - if (ctx_arg_info->offset == off && - (ctx_arg_info->reg_type == PTR_TO_RDONLY_BUF_OR_NULL || - ctx_arg_info->reg_type == PTR_TO_RDWR_BUF_OR_NULL)) { + type = base_type(ctx_arg_info->reg_type); + flag = type_flag(ctx_arg_info->reg_type); + if (ctx_arg_info->offset == off && type == PTR_TO_BUF && + (flag & PTR_MAYBE_NULL)) { info->reg_type = ctx_arg_info->reg_type; return true; } @@ -4945,7 +5478,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, */ return true; - if (is_string_ptr(btf, t)) + if (is_int_ptr(btf, t)) return true; /* this is a pointer to another type */ @@ -4987,6 +5520,15 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, info->btf = btf; info->btf_id = t->type; t = btf_type_by_id(btf, t->type); + + if (btf_type_is_type_tag(t)) { + tag_value = __btf_name_by_offset(btf, t->name_off); + if (strcmp(tag_value, "user") == 0) + info->reg_type |= MEM_USER; + if (strcmp(tag_value, "percpu") == 0) + info->reg_type |= MEM_PERCPU; + } + /* skip modifiers */ while (btf_type_is_modifier(t)) { info->btf_id = t->type; @@ -4995,11 +5537,11 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, if (!btf_type_is_struct(t)) { bpf_log(log, "func '%s' arg%d type %s is not a struct\n", - tname, arg, btf_kind_str[BTF_INFO_KIND(t->info)]); + tname, arg, btf_type_str(t)); return false; } bpf_log(log, "func '%s' arg%d has btf_id %d type %s '%s'\n", - tname, arg, info->btf_id, btf_kind_str[BTF_INFO_KIND(t->info)], + tname, arg, info->btf_id, btf_type_str(t), __btf_name_by_offset(btf, t->name_off)); return true; } @@ -5013,12 +5555,12 @@ enum bpf_struct_walk_result { static int btf_struct_walk(struct bpf_verifier_log *log, const struct btf *btf, const struct btf_type *t, int off, int size, - u32 *next_btf_id) + u32 *next_btf_id, enum bpf_type_flag *flag) { u32 i, moff, mtrue_end, msize = 0, total_nelems = 0; const struct btf_type *mtype, *elem_type = NULL; const struct btf_member *member; - const char *tname, *mname; + const char *tname, *mname, *tag_value; u32 vlen, elem_id, mid; again: @@ -5048,7 +5590,7 @@ again: if (array_elem->nelems != 0) goto error; - moff = btf_member_bit_offset(t, member) / 8; + moff = __btf_member_bit_offset(t, member) / 8; if (off < moff) goto error; @@ -5071,14 +5613,14 @@ error: for_each_member(i, t, member) { /* offset of the field in bytes */ - moff = btf_member_bit_offset(t, member) / 8; + moff = __btf_member_bit_offset(t, member) / 8; if (off + size <= moff) /* won't find anything, field is already too far */ break; - if (btf_member_bitfield_size(t, member)) { - u32 end_bit = btf_member_bit_offset(t, member) + - btf_member_bitfield_size(t, member); + if (__btf_member_bitfield_size(t, member)) { + u32 end_bit = __btf_member_bit_offset(t, member) + + __btf_member_bitfield_size(t, member); /* off <= moff instead of off == moff because clang * does not generate a BTF member for anonymous @@ -5202,7 +5744,8 @@ error: } if (btf_type_is_ptr(mtype)) { - const struct btf_type *stype; + const struct btf_type *stype, *t; + enum bpf_type_flag tmp_flag = 0; u32 id; if (msize != size || off != moff) { @@ -5211,9 +5754,23 @@ error: mname, moff, tname, off, size); return -EACCES; } + + /* check type tag */ + t = btf_type_by_id(btf, mtype->type); + if (btf_type_is_type_tag(t)) { + tag_value = __btf_name_by_offset(btf, t->name_off); + /* check __user tag */ + if (strcmp(tag_value, "user") == 0) + tmp_flag = MEM_USER; + /* check __percpu tag */ + if (strcmp(tag_value, "percpu") == 0) + tmp_flag = MEM_PERCPU; + } + stype = btf_type_skip_modifiers(btf, mtype->type, &id); if (btf_type_is_struct(stype)) { *next_btf_id = id; + *flag = tmp_flag; return WALK_PTR; } } @@ -5240,13 +5797,14 @@ error: int btf_struct_access(struct bpf_verifier_log *log, const struct btf *btf, const struct btf_type *t, int off, int size, enum bpf_access_type atype __maybe_unused, - u32 *next_btf_id) + u32 *next_btf_id, enum bpf_type_flag *flag) { + enum bpf_type_flag tmp_flag = 0; int err; u32 id; do { - err = btf_struct_walk(log, btf, t, off, size, &id); + err = btf_struct_walk(log, btf, t, off, size, &id, &tmp_flag); switch (err) { case WALK_PTR: @@ -5254,6 +5812,7 @@ int btf_struct_access(struct bpf_verifier_log *log, const struct btf *btf, * we're done. */ *next_btf_id = id; + *flag = tmp_flag; return PTR_TO_BTF_ID; case WALK_SCALAR: return SCALAR_VALUE; @@ -5295,20 +5854,27 @@ static bool btf_types_are_same(const struct btf *btf1, u32 id1, bool btf_struct_ids_match(struct bpf_verifier_log *log, const struct btf *btf, u32 id, int off, - const struct btf *need_btf, u32 need_type_id) + const struct btf *need_btf, u32 need_type_id, + bool strict) { const struct btf_type *type; + enum bpf_type_flag flag; int err; /* Are we already done? */ if (off == 0 && btf_types_are_same(btf, id, need_btf, need_type_id)) return true; - + /* In case of strict type match, we do not walk struct, the top level + * type match must succeed. When strict is true, off should have already + * been 0. + */ + if (strict) + return false; again: type = btf_type_by_id(btf, id); if (!type) return false; - err = btf_struct_walk(log, btf, type, off, 1, &id); + err = btf_struct_walk(log, btf, type, off, 1, &id, &flag); if (err != WALK_STRUCT) return false; @@ -5326,26 +5892,25 @@ again: } static int __get_type_size(struct btf *btf, u32 btf_id, - const struct btf_type **bad_type) + const struct btf_type **ret_type) { const struct btf_type *t; + *ret_type = btf_type_by_id(btf, 0); if (!btf_id) /* void */ return 0; t = btf_type_by_id(btf, btf_id); while (t && btf_type_is_modifier(t)) t = btf_type_by_id(btf, t->type); - if (!t) { - *bad_type = btf_type_by_id(btf, 0); + if (!t) return -EINVAL; - } + *ret_type = t; if (btf_type_is_ptr(t)) /* kernel size of pointer. Not BPF's size of pointer*/ return sizeof(void *); - if (btf_type_is_int(t) || btf_type_is_enum(t)) + if (btf_type_is_int(t) || btf_is_any_enum(t) || __btf_type_is_struct(t)) return t->size; - *bad_type = t; return -EINVAL; } @@ -5364,25 +5929,27 @@ int btf_distill_func_proto(struct bpf_verifier_log *log, /* BTF function prototype doesn't match the verifier types. * Fall back to MAX_BPF_FUNC_REG_ARGS u64 args. */ - for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) + for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) { m->arg_size[i] = 8; + m->arg_flags[i] = 0; + } m->ret_size = 8; m->nr_args = MAX_BPF_FUNC_REG_ARGS; return 0; } args = (const struct btf_param *)(func + 1); nargs = btf_type_vlen(func); - if (nargs >= MAX_BPF_FUNC_ARGS) { + if (nargs > MAX_BPF_FUNC_ARGS) { bpf_log(log, "The function %s has %d arguments. Too many.\n", tname, nargs); return -EINVAL; } ret = __get_type_size(btf, func->type, &t); - if (ret < 0) { + if (ret < 0 || __btf_type_is_struct(t)) { bpf_log(log, "The function %s return type %s is unsupported.\n", - tname, btf_kind_str[BTF_INFO_KIND(t->info)]); + tname, btf_type_str(t)); return -EINVAL; } m->ret_size = ret; @@ -5395,10 +5962,12 @@ int btf_distill_func_proto(struct bpf_verifier_log *log, return -EINVAL; } ret = __get_type_size(btf, args[i].type, &t); - if (ret < 0) { + + /* No support of struct argument size greater than 16 bytes */ + if (ret < 0 || ret > 16) { bpf_log(log, "The function %s arg%d type %s is unsupported.\n", - tname, i, btf_kind_str[BTF_INFO_KIND(t->info)]); + tname, i, btf_type_str(t)); return -EINVAL; } if (ret == 0) { @@ -5408,6 +5977,7 @@ int btf_distill_func_proto(struct bpf_verifier_log *log, return -EINVAL; } m->arg_size[i] = ret; + m->arg_flags[i] = __btf_type_is_struct(t) ? BTF_FMODEL_STRUCT_ARG : 0; } m->nr_args = nargs; return 0; @@ -5491,7 +6061,7 @@ static int btf_check_func_type_match(struct bpf_verifier_log *log, * to context only. And only global functions can be replaced. * Hence type check only those types. */ - if (btf_type_is_int(t1) || btf_type_is_enum(t1)) + if (btf_type_is_int(t1) || btf_is_any_enum(t1)) continue; if (!btf_type_is_ptr(t1)) { bpf_log(log, @@ -5563,16 +6133,114 @@ static u32 *reg2btf_ids[__BPF_REG_TYPE_MAX] = { #endif }; +/* Returns true if struct is composed of scalars, 4 levels of nesting allowed */ +static bool __btf_type_is_scalar_struct(struct bpf_verifier_log *log, + const struct btf *btf, + const struct btf_type *t, int rec) +{ + const struct btf_type *member_type; + const struct btf_member *member; + u32 i; + + if (!btf_type_is_struct(t)) + return false; + + for_each_member(i, t, member) { + const struct btf_array *array; + + member_type = btf_type_skip_modifiers(btf, member->type, NULL); + if (btf_type_is_struct(member_type)) { + if (rec >= 3) { + bpf_log(log, "max struct nesting depth exceeded\n"); + return false; + } + if (!__btf_type_is_scalar_struct(log, btf, member_type, rec + 1)) + return false; + continue; + } + if (btf_type_is_array(member_type)) { + array = btf_type_array(member_type); + if (!array->nelems) + return false; + member_type = btf_type_skip_modifiers(btf, array->type, NULL); + if (!btf_type_is_scalar(member_type)) + return false; + continue; + } + if (!btf_type_is_scalar(member_type)) + return false; + } + return true; +} + +static bool is_kfunc_arg_mem_size(const struct btf *btf, + const struct btf_param *arg, + const struct bpf_reg_state *reg) +{ + int len, sfx_len = sizeof("__sz") - 1; + const struct btf_type *t; + const char *param_name; + + t = btf_type_skip_modifiers(btf, arg->type, NULL); + if (!btf_type_is_scalar(t) || reg->type != SCALAR_VALUE) + return false; + + /* In the future, this can be ported to use BTF tagging */ + param_name = btf_name_by_offset(btf, arg->name_off); + if (str_is_empty(param_name)) + return false; + len = strlen(param_name); + if (len < sfx_len) + return false; + param_name += len - sfx_len; + if (strncmp(param_name, "__sz", sfx_len)) + return false; + + return true; +} + +static bool btf_is_kfunc_arg_mem_size(const struct btf *btf, + const struct btf_param *arg, + const struct bpf_reg_state *reg, + const char *name) +{ + int len, target_len = strlen(name); + const struct btf_type *t; + const char *param_name; + + t = btf_type_skip_modifiers(btf, arg->type, NULL); + if (!btf_type_is_scalar(t) || reg->type != SCALAR_VALUE) + return false; + + param_name = btf_name_by_offset(btf, arg->name_off); + if (str_is_empty(param_name)) + return false; + len = strlen(param_name); + if (len != target_len) + return false; + if (strcmp(param_name, name)) + return false; + + return true; +} + static int btf_check_func_arg_match(struct bpf_verifier_env *env, const struct btf *btf, u32 func_id, struct bpf_reg_state *regs, - bool ptr_to_mem_ok) + bool ptr_to_mem_ok, + struct bpf_kfunc_arg_meta *kfunc_meta, + bool processing_call) { + enum bpf_prog_type prog_type = resolve_prog_type(env->prog); + bool rel = false, kptr_get = false, trusted_args = false; + bool sleepable = false; struct bpf_verifier_log *log = &env->log; + u32 i, nargs, ref_id, ref_obj_id = 0; + bool is_kfunc = btf_is_kernel(btf); const char *func_name, *ref_tname; const struct btf_type *t, *ref_t; const struct btf_param *args; - u32 i, nargs, ref_id; + int ref_regno = 0, ret; t = btf_type_by_id(btf, func_id); if (!t || !btf_type_is_func(t)) { @@ -5598,15 +6266,57 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, return -EINVAL; } + if (is_kfunc && kfunc_meta) { + /* Only kfunc can be release func */ + rel = kfunc_meta->flags & KF_RELEASE; + kptr_get = kfunc_meta->flags & KF_KPTR_GET; + trusted_args = kfunc_meta->flags & KF_TRUSTED_ARGS; + sleepable = kfunc_meta->flags & KF_SLEEPABLE; + } + /* check that BTF function arguments match actual types that the * verifier sees. */ for (i = 0; i < nargs; i++) { + enum bpf_arg_type arg_type = ARG_DONTCARE; u32 regno = i + 1; struct bpf_reg_state *reg = ®s[regno]; + bool obj_ptr = false; t = btf_type_skip_modifiers(btf, args[i].type, NULL); if (btf_type_is_scalar(t)) { + if (is_kfunc && kfunc_meta) { + bool is_buf_size = false; + + /* check for any const scalar parameter of name "rdonly_buf_size" + * or "rdwr_buf_size" + */ + if (btf_is_kfunc_arg_mem_size(btf, &args[i], reg, + "rdonly_buf_size")) { + kfunc_meta->r0_rdonly = true; + is_buf_size = true; + } else if (btf_is_kfunc_arg_mem_size(btf, &args[i], reg, + "rdwr_buf_size")) + is_buf_size = true; + + if (is_buf_size) { + if (kfunc_meta->r0_size) { + bpf_log(log, "2 or more rdonly/rdwr_buf_size parameters for kfunc"); + return -EINVAL; + } + + if (!tnum_is_const(reg->var_off)) { + bpf_log(log, "R%d is not a const\n", regno); + return -EINVAL; + } + + kfunc_meta->r0_size = reg->var_off.value; + ret = mark_chain_precision(env, regno); + if (ret) + return ret; + } + } + if (reg->type == SCALAR_VALUE) continue; bpf_log(log, "R%d is not a scalar\n", regno); @@ -5619,9 +6329,99 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, return -EINVAL; } + /* These register types have special constraints wrt ref_obj_id + * and offset checks. The rest of trusted args don't. + */ + obj_ptr = reg->type == PTR_TO_CTX || reg->type == PTR_TO_BTF_ID || + reg2btf_ids[base_type(reg->type)]; + + /* Check if argument must be a referenced pointer, args + i has + * been verified to be a pointer (after skipping modifiers). + * PTR_TO_CTX is ok without having non-zero ref_obj_id. + */ + if (is_kfunc && trusted_args && (obj_ptr && reg->type != PTR_TO_CTX) && !reg->ref_obj_id) { + bpf_log(log, "R%d must be referenced\n", regno); + return -EINVAL; + } + ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id); ref_tname = btf_name_by_offset(btf, ref_t->name_off); - if (btf_is_kernel(btf)) { + + /* Trusted args have the same offset checks as release arguments */ + if ((trusted_args && obj_ptr) || (rel && reg->ref_obj_id)) + arg_type |= OBJ_RELEASE; + ret = check_func_arg_reg_off(env, reg, regno, arg_type); + if (ret < 0) + return ret; + + if (is_kfunc && reg->ref_obj_id) { + /* Ensure only one argument is referenced PTR_TO_BTF_ID */ + if (ref_obj_id) { + bpf_log(log, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n", + regno, reg->ref_obj_id, ref_obj_id); + return -EFAULT; + } + ref_regno = regno; + ref_obj_id = reg->ref_obj_id; + } + + /* kptr_get is only true for kfunc */ + if (i == 0 && kptr_get) { + struct bpf_map_value_off_desc *off_desc; + + if (reg->type != PTR_TO_MAP_VALUE) { + bpf_log(log, "arg#0 expected pointer to map value\n"); + return -EINVAL; + } + + /* check_func_arg_reg_off allows var_off for + * PTR_TO_MAP_VALUE, but we need fixed offset to find + * off_desc. + */ + if (!tnum_is_const(reg->var_off)) { + bpf_log(log, "arg#0 must have constant offset\n"); + return -EINVAL; + } + + off_desc = bpf_map_kptr_off_contains(reg->map_ptr, reg->off + reg->var_off.value); + if (!off_desc || off_desc->type != BPF_KPTR_REF) { + bpf_log(log, "arg#0 no referenced kptr at map value offset=%llu\n", + reg->off + reg->var_off.value); + return -EINVAL; + } + + if (!btf_type_is_ptr(ref_t)) { + bpf_log(log, "arg#0 BTF type must be a double pointer\n"); + return -EINVAL; + } + + ref_t = btf_type_skip_modifiers(btf, ref_t->type, &ref_id); + ref_tname = btf_name_by_offset(btf, ref_t->name_off); + + if (!btf_type_is_struct(ref_t)) { + bpf_log(log, "kernel function %s args#%d pointer type %s %s is not supported\n", + func_name, i, btf_type_str(ref_t), ref_tname); + return -EINVAL; + } + if (!btf_struct_ids_match(log, btf, ref_id, 0, off_desc->kptr.btf, + off_desc->kptr.btf_id, true)) { + bpf_log(log, "kernel function %s args#%d expected pointer to %s %s\n", + func_name, i, btf_type_str(ref_t), ref_tname); + return -EINVAL; + } + /* rest of the arguments can be anything, like normal kfunc */ + } else if (btf_get_prog_ctx_type(log, btf, t, prog_type, i)) { + /* If function expects ctx type in BTF check that caller + * is passing PTR_TO_CTX. + */ + if (reg->type != PTR_TO_CTX) { + bpf_log(log, + "arg#%d expected pointer to ctx, but got %s\n", + i, btf_type_str(t)); + return -EINVAL; + } + } else if (is_kfunc && (reg->type == PTR_TO_BTF_ID || + (reg2btf_ids[base_type(reg->type)] && !type_flag(reg->type)))) { const struct btf_type *reg_ref_t; const struct btf *reg_btf; const char *reg_ref_tname; @@ -5637,14 +6437,9 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, if (reg->type == PTR_TO_BTF_ID) { reg_btf = reg->btf; reg_ref_id = reg->btf_id; - } else if (reg2btf_ids[reg->type]) { - reg_btf = btf_vmlinux; - reg_ref_id = *reg2btf_ids[reg->type]; } else { - bpf_log(log, "kernel function %s args#%d expected pointer to %s %s but R%d is not a pointer to btf_id\n", - func_name, i, - btf_type_str(ref_t), ref_tname, regno); - return -EINVAL; + reg_btf = btf_vmlinux; + reg_ref_id = *reg2btf_ids[base_type(reg->type)]; } reg_ref_t = btf_type_skip_modifiers(reg_btf, reg_ref_id, @@ -5652,7 +6447,8 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, reg_ref_tname = btf_name_by_offset(reg_btf, reg_ref_t->name_off); if (!btf_struct_ids_match(log, reg_btf, reg_ref_id, - reg->off, btf, ref_id)) { + reg->off, btf, ref_id, + trusted_args || (rel && reg->ref_obj_id))) { bpf_log(log, "kernel function %s args#%d expected pointer to %s %s but R%d has a pointer to %s %s\n", func_name, i, btf_type_str(ref_t), ref_tname, @@ -5660,23 +6456,73 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, reg_ref_tname); return -EINVAL; } - } else if (btf_get_prog_ctx_type(log, btf, t, - env->prog->type, i)) { - /* If function expects ctx type in BTF check that caller - * is passing PTR_TO_CTX. - */ - if (reg->type != PTR_TO_CTX) { - bpf_log(log, - "arg#%d expected pointer to ctx, but got %s\n", - i, btf_type_str(t)); - return -EINVAL; - } - if (check_ctx_reg(env, reg, regno)) - return -EINVAL; - } else if (ptr_to_mem_ok) { + } else if (ptr_to_mem_ok && processing_call) { const struct btf_type *resolve_ret; u32 type_size; + if (is_kfunc) { + bool arg_mem_size = i + 1 < nargs && is_kfunc_arg_mem_size(btf, &args[i + 1], ®s[regno + 1]); + bool arg_dynptr = btf_type_is_struct(ref_t) && + !strcmp(ref_tname, + stringify_struct(bpf_dynptr_kern)); + + /* Permit pointer to mem, but only when argument + * type is pointer to scalar, or struct composed + * (recursively) of scalars. + * When arg_mem_size is true, the pointer can be + * void *. + * Also permit initialized local dynamic pointers. + */ + if (!btf_type_is_scalar(ref_t) && + !__btf_type_is_scalar_struct(log, btf, ref_t, 0) && + !arg_dynptr && + (arg_mem_size ? !btf_type_is_void(ref_t) : 1)) { + bpf_log(log, + "arg#%d pointer type %s %s must point to %sscalar, or struct with scalar\n", + i, btf_type_str(ref_t), ref_tname, arg_mem_size ? "void, " : ""); + return -EINVAL; + } + + if (arg_dynptr) { + if (reg->type != PTR_TO_STACK) { + bpf_log(log, "arg#%d pointer type %s %s not to stack\n", + i, btf_type_str(ref_t), + ref_tname); + return -EINVAL; + } + + if (!is_dynptr_reg_valid_init(env, reg)) { + bpf_log(log, + "arg#%d pointer type %s %s must be valid and initialized\n", + i, btf_type_str(ref_t), + ref_tname); + return -EINVAL; + } + + if (!is_dynptr_type_expected(env, reg, + ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_LOCAL)) { + bpf_log(log, + "arg#%d pointer type %s %s points to unsupported dynamic pointer type\n", + i, btf_type_str(ref_t), + ref_tname); + return -EINVAL; + } + + continue; + } + + /* Check for mem, len pair */ + if (arg_mem_size) { + if (check_kfunc_mem_size_reg(env, ®s[regno + 1], regno + 1)) { + bpf_log(log, "arg#%d arg#%d memory, len pair leads to invalid memory access\n", + i, i + 1); + return -EINVAL; + } + i++; + continue; + } + } + resolve_ret = btf_resolve_size(btf, ref_t, &type_size); if (IS_ERR(resolve_ret)) { bpf_log(log, @@ -5689,14 +6535,39 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, if (check_mem_reg(env, reg, regno, type_size)) return -EINVAL; } else { + bpf_log(log, "reg type unsupported for arg#%d %sfunction %s#%d\n", i, + is_kfunc ? "kernel " : "", func_name, func_id); return -EINVAL; } } - return 0; + /* Either both are set, or neither */ + WARN_ON_ONCE((ref_obj_id && !ref_regno) || (!ref_obj_id && ref_regno)); + /* We already made sure ref_obj_id is set only for one argument. We do + * allow (!rel && ref_obj_id), so that passing such referenced + * PTR_TO_BTF_ID to other kfuncs works. Note that rel is only true when + * is_kfunc is true. + */ + if (rel && !ref_obj_id) { + bpf_log(log, "release kernel function %s expects refcounted PTR_TO_BTF_ID\n", + func_name); + return -EINVAL; + } + + if (sleepable && !env->prog->aux->sleepable) { + bpf_log(log, "kernel function %s is sleepable but the program is not\n", + func_name); + return -EINVAL; + } + + if (kfunc_meta && ref_obj_id) + kfunc_meta->ref_obj_id = ref_obj_id; + + /* returns argument register number > 0 in case of reference release kfunc */ + return rel ? ref_regno : 0; } -/* Compare BTF of a function with given bpf_reg_state. +/* Compare BTF of a function declaration with given bpf_reg_state. * Returns: * EFAULT - there is a verifier bug. Abort verification. * EINVAL - there is a type mismatch or BTF is not available. @@ -5723,7 +6594,50 @@ int btf_check_subprog_arg_match(struct bpf_verifier_env *env, int subprog, return -EINVAL; is_global = prog->aux->func_info_aux[subprog].linkage == BTF_FUNC_GLOBAL; - err = btf_check_func_arg_match(env, btf, btf_id, regs, is_global); + err = btf_check_func_arg_match(env, btf, btf_id, regs, is_global, NULL, false); + + /* Compiler optimizations can remove arguments from static functions + * or mismatched type can be passed into a global function. + * In such cases mark the function as unreliable from BTF point of view. + */ + if (err) + prog->aux->func_info_aux[subprog].unreliable = true; + return err; +} + +/* Compare BTF of a function call with given bpf_reg_state. + * Returns: + * EFAULT - there is a verifier bug. Abort verification. + * EINVAL - there is a type mismatch or BTF is not available. + * 0 - BTF matches with what bpf_reg_state expects. + * Only PTR_TO_CTX and SCALAR_VALUE states are recognized. + * + * NOTE: the code is duplicated from btf_check_subprog_arg_match() + * because btf_check_func_arg_match() is still doing both. Once that + * function is split in 2, we can call from here btf_check_subprog_arg_match() + * first, and then treat the calling part in a new code path. + */ +int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog, + struct bpf_reg_state *regs) +{ + struct bpf_prog *prog = env->prog; + struct btf *btf = prog->aux->btf; + bool is_global; + u32 btf_id; + int err; + + if (!prog->aux->func_info) + return -EINVAL; + + btf_id = prog->aux->func_info[subprog].type_id; + if (!btf_id) + return -EFAULT; + + if (prog->aux->func_info_aux[subprog].unreliable) + return -EINVAL; + + is_global = prog->aux->func_info_aux[subprog].linkage == BTF_FUNC_GLOBAL; + err = btf_check_func_arg_match(env, btf, btf_id, regs, is_global, NULL, true); /* Compiler optimizations can remove arguments from static functions * or mismatched type can be passed into a global function. @@ -5736,9 +6650,10 @@ int btf_check_subprog_arg_match(struct bpf_verifier_env *env, int subprog, int btf_check_kfunc_arg_match(struct bpf_verifier_env *env, const struct btf *btf, u32 func_id, - struct bpf_reg_state *regs) + struct bpf_reg_state *regs, + struct bpf_kfunc_arg_meta *meta) { - return btf_check_func_arg_match(env, btf, func_id, regs, false); + return btf_check_func_arg_match(env, btf, func_id, regs, true, meta, true); } /* Convert BTF of a function into bpf_reg_state if possible @@ -5810,7 +6725,7 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog, t = btf_type_by_id(btf, t->type); while (btf_type_is_modifier(t)) t = btf_type_by_id(btf, t->type); - if (!btf_type_is_int(t) && !btf_type_is_enum(t)) { + if (!btf_type_is_int(t) && !btf_is_any_enum(t)) { bpf_log(log, "Global function %s() doesn't return scalar. Only those are supported.\n", tname); @@ -5825,7 +6740,7 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog, t = btf_type_by_id(btf, args[i].type); while (btf_type_is_modifier(t)) t = btf_type_by_id(btf, t->type); - if (btf_type_is_int(t) || btf_type_is_enum(t)) { + if (btf_type_is_int(t) || btf_is_any_enum(t)) { reg->type = SCALAR_VALUE; continue; } @@ -5846,13 +6761,13 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog, return -EINVAL; } - reg->type = PTR_TO_MEM_OR_NULL; + reg->type = PTR_TO_MEM | PTR_MAYBE_NULL; reg->id = ++env->id_gen; continue; } bpf_log(log, "Arg#%d type %s in %s() is not supported yet.\n", - i, btf_kind_str[BTF_INFO_KIND(t->info)], tname); + i, btf_type_str(t), tname); return -EINVAL; } return 0; @@ -5915,7 +6830,7 @@ static void btf_snprintf_show(struct btf_show *show, const char *fmt, if (len < 0) { ssnprintf->len_left = 0; ssnprintf->len = len; - } else if (len > ssnprintf->len_left) { + } else if (len >= ssnprintf->len_left) { /* no space, drive on to get length we would have written */ ssnprintf->len_left = 0; ssnprintf->len += len; @@ -5939,7 +6854,7 @@ int btf_type_snprintf_show(const struct btf *btf, u32 type_id, void *obj, btf_type_show(btf, type_id, obj, (struct btf_show *)&ssnprintf); - /* If we encontered an error, return it. */ + /* If we encountered an error, return it. */ if (ssnprintf.show.state.status) return ssnprintf.show.state.status; @@ -6135,12 +7050,22 @@ bool btf_id_set_contains(const struct btf_id_set *set, u32 id) return bsearch(&id, set->ids, set->cnt, sizeof(u32), btf_id_cmp_func) != NULL; } +static void *btf_id_set8_contains(const struct btf_id_set8 *set, u32 id) +{ + return bsearch(&id, set->pairs, set->cnt, sizeof(set->pairs[0]), btf_id_cmp_func); +} + +enum { + BTF_MODULE_F_LIVE = (1 << 0), +}; + #ifdef CONFIG_DEBUG_INFO_BTF_MODULES struct btf_module { struct list_head list; struct module *module; struct btf *btf; struct bin_attribute *sysfs_attr; + int flags; }; static LIST_HEAD(btf_modules); @@ -6157,6 +7082,8 @@ btf_module_read(struct file *file, struct kobject *kobj, return len; } +static void purge_cand_cache(struct btf *btf); + static int btf_module_notify(struct notifier_block *nb, unsigned long op, void *module) { @@ -6166,7 +7093,8 @@ static int btf_module_notify(struct notifier_block *nb, unsigned long op, int err = 0; if (mod->btf_data_size == 0 || - (op != MODULE_STATE_COMING && op != MODULE_STATE_GOING)) + (op != MODULE_STATE_COMING && op != MODULE_STATE_LIVE && + op != MODULE_STATE_GOING)) goto out; switch (op) { @@ -6181,7 +7109,8 @@ static int btf_module_notify(struct notifier_block *nb, unsigned long op, pr_warn("failed to validate module [%s] BTF: %ld\n", mod->name, PTR_ERR(btf)); kfree(btf_mod); - err = PTR_ERR(btf); + if (!IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH)) + err = PTR_ERR(btf); goto out; } err = btf_alloc_id(btf); @@ -6191,6 +7120,7 @@ static int btf_module_notify(struct notifier_block *nb, unsigned long op, goto out; } + purge_cand_cache(NULL); mutex_lock(&btf_module_mutex); btf_mod->module = module; btf_mod->btf = btf; @@ -6224,6 +7154,17 @@ static int btf_module_notify(struct notifier_block *nb, unsigned long op, } break; + case MODULE_STATE_LIVE: + mutex_lock(&btf_module_mutex); + list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) { + if (btf_mod->module != module) + continue; + + btf_mod->flags |= BTF_MODULE_F_LIVE; + break; + } + mutex_unlock(&btf_module_mutex); + break; case MODULE_STATE_GOING: mutex_lock(&btf_module_mutex); list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) { @@ -6233,6 +7174,7 @@ static int btf_module_notify(struct notifier_block *nb, unsigned long op, list_del(&btf_mod->list); if (btf_mod->sysfs_attr) sysfs_remove_bin_file(btf_kobj, btf_mod->sysfs_attr); + purge_cand_cache(btf_mod->btf); btf_put(btf_mod->btf); kfree(btf_mod->sysfs_attr); kfree(btf_mod); @@ -6269,7 +7211,12 @@ struct module *btf_try_get_module(const struct btf *btf) if (btf_mod->btf != btf) continue; - if (try_module_get(btf_mod->module)) + /* We must only consider module whose __init routine has + * finished, hence we must check for BTF_MODULE_F_LIVE flag, + * which is set from the notifier callback for + * MODULE_STATE_LIVE. + */ + if ((btf_mod->flags & BTF_MODULE_F_LIVE) && try_module_get(btf_mod->module)) res = btf_mod->module; break; @@ -6280,9 +7227,43 @@ struct module *btf_try_get_module(const struct btf *btf) return res; } +/* Returns struct btf corresponding to the struct module. + * This function can return NULL or ERR_PTR. + */ +static struct btf *btf_get_module_btf(const struct module *module) +{ +#ifdef CONFIG_DEBUG_INFO_BTF_MODULES + struct btf_module *btf_mod, *tmp; +#endif + struct btf *btf = NULL; + + if (!module) { + btf = bpf_get_btf_vmlinux(); + if (!IS_ERR_OR_NULL(btf)) + btf_get(btf); + return btf; + } + +#ifdef CONFIG_DEBUG_INFO_BTF_MODULES + mutex_lock(&btf_module_mutex); + list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) { + if (btf_mod->module != module) + continue; + + btf_get(btf_mod->btf); + btf = btf_mod->btf; + break; + } + mutex_unlock(&btf_module_mutex); +#endif + + return btf; +} + BPF_CALL_4(bpf_btf_find_by_name_kind, char *, name, int, name_sz, u32, kind, int, flags) { - struct btf *btf; + struct btf *btf = NULL; + int btf_obj_fd = 0; long ret; if (flags) @@ -6291,44 +7272,17 @@ BPF_CALL_4(bpf_btf_find_by_name_kind, char *, name, int, name_sz, u32, kind, int if (name_sz <= 1 || name[name_sz - 1]) return -EINVAL; - btf = bpf_get_btf_vmlinux(); - if (IS_ERR(btf)) - return PTR_ERR(btf); - - ret = btf_find_by_name_kind(btf, name, kind); - /* ret is never zero, since btf_find_by_name_kind returns - * positive btf_id or negative error. - */ - if (ret < 0) { - struct btf *mod_btf; - int id; - - /* If name is not found in vmlinux's BTF then search in module's BTFs */ - spin_lock_bh(&btf_idr_lock); - idr_for_each_entry(&btf_idr, mod_btf, id) { - if (!btf_is_module(mod_btf)) - continue; - /* linear search could be slow hence unlock/lock - * the IDR to avoiding holding it for too long - */ - btf_get(mod_btf); - spin_unlock_bh(&btf_idr_lock); - ret = btf_find_by_name_kind(mod_btf, name, kind); - if (ret > 0) { - int btf_obj_fd; - - btf_obj_fd = __btf_new_fd(mod_btf); - if (btf_obj_fd < 0) { - btf_put(mod_btf); - return btf_obj_fd; - } - return ret | (((u64)btf_obj_fd) << 32); - } - spin_lock_bh(&btf_idr_lock); - btf_put(mod_btf); + ret = bpf_find_btf_id(name, kind, &btf); + if (ret > 0 && btf_is_module(btf)) { + btf_obj_fd = __btf_new_fd(btf); + if (btf_obj_fd < 0) { + btf_put(btf); + return btf_obj_fd; } - spin_unlock_bh(&btf_idr_lock); + return ret | (((u64)btf_obj_fd) << 32); } + if (ret > 0) + btf_put(btf); return ret; } @@ -6336,58 +7290,743 @@ const struct bpf_func_proto bpf_btf_find_by_name_kind_proto = { .func = bpf_btf_find_by_name_kind, .gpl_only = false, .ret_type = RET_INTEGER, - .arg1_type = ARG_PTR_TO_MEM, + .arg1_type = ARG_PTR_TO_MEM | MEM_RDONLY, .arg2_type = ARG_CONST_SIZE, .arg3_type = ARG_ANYTHING, .arg4_type = ARG_ANYTHING, }; -BTF_ID_LIST_GLOBAL_SINGLE(btf_task_struct_ids, struct, task_struct) +BTF_ID_LIST_GLOBAL(btf_tracing_ids, MAX_BTF_TRACING_TYPE) +#define BTF_TRACING_TYPE(name, type) BTF_ID(struct, type) +BTF_TRACING_TYPE_xxx +#undef BTF_TRACING_TYPE -/* BTF ID set registration API for modules */ +/* Kernel Function (kfunc) BTF ID set registration API */ -#ifdef CONFIG_DEBUG_INFO_BTF_MODULES +static int btf_populate_kfunc_set(struct btf *btf, enum btf_kfunc_hook hook, + struct btf_id_set8 *add_set) +{ + bool vmlinux_set = !btf_is_module(btf); + struct btf_kfunc_set_tab *tab; + struct btf_id_set8 *set; + u32 set_cnt; + int ret; + + if (hook >= BTF_KFUNC_HOOK_MAX) { + ret = -EINVAL; + goto end; + } + + if (!add_set->cnt) + return 0; + + tab = btf->kfunc_set_tab; + if (!tab) { + tab = kzalloc(sizeof(*tab), GFP_KERNEL | __GFP_NOWARN); + if (!tab) + return -ENOMEM; + btf->kfunc_set_tab = tab; + } + + set = tab->sets[hook]; + /* Warn when register_btf_kfunc_id_set is called twice for the same hook + * for module sets. + */ + if (WARN_ON_ONCE(set && !vmlinux_set)) { + ret = -EINVAL; + goto end; + } -void register_kfunc_btf_id_set(struct kfunc_btf_id_list *l, - struct kfunc_btf_id_set *s) + /* We don't need to allocate, concatenate, and sort module sets, because + * only one is allowed per hook. Hence, we can directly assign the + * pointer and return. + */ + if (!vmlinux_set) { + tab->sets[hook] = add_set; + return 0; + } + + /* In case of vmlinux sets, there may be more than one set being + * registered per hook. To create a unified set, we allocate a new set + * and concatenate all individual sets being registered. While each set + * is individually sorted, they may become unsorted when concatenated, + * hence re-sorting the final set again is required to make binary + * searching the set using btf_id_set8_contains function work. + */ + set_cnt = set ? set->cnt : 0; + + if (set_cnt > U32_MAX - add_set->cnt) { + ret = -EOVERFLOW; + goto end; + } + + if (set_cnt + add_set->cnt > BTF_KFUNC_SET_MAX_CNT) { + ret = -E2BIG; + goto end; + } + + /* Grow set */ + set = krealloc(tab->sets[hook], + offsetof(struct btf_id_set8, pairs[set_cnt + add_set->cnt]), + GFP_KERNEL | __GFP_NOWARN); + if (!set) { + ret = -ENOMEM; + goto end; + } + + /* For newly allocated set, initialize set->cnt to 0 */ + if (!tab->sets[hook]) + set->cnt = 0; + tab->sets[hook] = set; + + /* Concatenate the two sets */ + memcpy(set->pairs + set->cnt, add_set->pairs, add_set->cnt * sizeof(set->pairs[0])); + set->cnt += add_set->cnt; + + sort(set->pairs, set->cnt, sizeof(set->pairs[0]), btf_id_cmp_func, NULL); + + return 0; +end: + btf_free_kfunc_set_tab(btf); + return ret; +} + +static u32 *__btf_kfunc_id_set_contains(const struct btf *btf, + enum btf_kfunc_hook hook, + u32 kfunc_btf_id) { - mutex_lock(&l->mutex); - list_add(&s->list, &l->list); - mutex_unlock(&l->mutex); + struct btf_id_set8 *set; + u32 *id; + + if (hook >= BTF_KFUNC_HOOK_MAX) + return NULL; + if (!btf->kfunc_set_tab) + return NULL; + set = btf->kfunc_set_tab->sets[hook]; + if (!set) + return NULL; + id = btf_id_set8_contains(set, kfunc_btf_id); + if (!id) + return NULL; + /* The flags for BTF ID are located next to it */ + return id + 1; +} + +static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type) +{ + switch (prog_type) { + case BPF_PROG_TYPE_XDP: + return BTF_KFUNC_HOOK_XDP; + case BPF_PROG_TYPE_SCHED_CLS: + return BTF_KFUNC_HOOK_TC; + case BPF_PROG_TYPE_STRUCT_OPS: + return BTF_KFUNC_HOOK_STRUCT_OPS; + case BPF_PROG_TYPE_TRACING: + case BPF_PROG_TYPE_LSM: + return BTF_KFUNC_HOOK_TRACING; + case BPF_PROG_TYPE_SYSCALL: + return BTF_KFUNC_HOOK_SYSCALL; + default: + return BTF_KFUNC_HOOK_MAX; + } } -EXPORT_SYMBOL_GPL(register_kfunc_btf_id_set); -void unregister_kfunc_btf_id_set(struct kfunc_btf_id_list *l, - struct kfunc_btf_id_set *s) +/* Caution: + * Reference to the module (obtained using btf_try_get_module) corresponding to + * the struct btf *MUST* be held when calling this function from verifier + * context. This is usually true as we stash references in prog's kfunc_btf_tab; + * keeping the reference for the duration of the call provides the necessary + * protection for looking up a well-formed btf->kfunc_set_tab. + */ +u32 *btf_kfunc_id_set_contains(const struct btf *btf, + enum bpf_prog_type prog_type, + u32 kfunc_btf_id) { - mutex_lock(&l->mutex); - list_del_init(&s->list); - mutex_unlock(&l->mutex); + enum btf_kfunc_hook hook; + + hook = bpf_prog_type_to_kfunc_hook(prog_type); + return __btf_kfunc_id_set_contains(btf, hook, kfunc_btf_id); } -EXPORT_SYMBOL_GPL(unregister_kfunc_btf_id_set); -bool bpf_check_mod_kfunc_call(struct kfunc_btf_id_list *klist, u32 kfunc_id, - struct module *owner) +/* This function must be invoked only from initcalls/module init functions */ +int register_btf_kfunc_id_set(enum bpf_prog_type prog_type, + const struct btf_kfunc_id_set *kset) { - struct kfunc_btf_id_set *s; + enum btf_kfunc_hook hook; + struct btf *btf; + int ret; - mutex_lock(&klist->mutex); - list_for_each_entry(s, &klist->list, list) { - if (s->owner == owner && btf_id_set_contains(s->set, kfunc_id)) { - mutex_unlock(&klist->mutex); - return true; + btf = btf_get_module_btf(kset->owner); + if (!btf) { + if (!kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) { + pr_err("missing vmlinux BTF, cannot register kfuncs\n"); + return -ENOENT; + } + if (kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) { + pr_err("missing module BTF, cannot register kfuncs\n"); + return -ENOENT; } + return 0; } - mutex_unlock(&klist->mutex); - return false; + if (IS_ERR(btf)) + return PTR_ERR(btf); + + hook = bpf_prog_type_to_kfunc_hook(prog_type); + ret = btf_populate_kfunc_set(btf, hook, kset->set); + btf_put(btf); + return ret; +} +EXPORT_SYMBOL_GPL(register_btf_kfunc_id_set); + +s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id) +{ + struct btf_id_dtor_kfunc_tab *tab = btf->dtor_kfunc_tab; + struct btf_id_dtor_kfunc *dtor; + + if (!tab) + return -ENOENT; + /* Even though the size of tab->dtors[0] is > sizeof(u32), we only need + * to compare the first u32 with btf_id, so we can reuse btf_id_cmp_func. + */ + BUILD_BUG_ON(offsetof(struct btf_id_dtor_kfunc, btf_id) != 0); + dtor = bsearch(&btf_id, tab->dtors, tab->cnt, sizeof(tab->dtors[0]), btf_id_cmp_func); + if (!dtor) + return -ENOENT; + return dtor->kfunc_btf_id; +} + +static int btf_check_dtor_kfuncs(struct btf *btf, const struct btf_id_dtor_kfunc *dtors, u32 cnt) +{ + const struct btf_type *dtor_func, *dtor_func_proto, *t; + const struct btf_param *args; + s32 dtor_btf_id; + u32 nr_args, i; + + for (i = 0; i < cnt; i++) { + dtor_btf_id = dtors[i].kfunc_btf_id; + + dtor_func = btf_type_by_id(btf, dtor_btf_id); + if (!dtor_func || !btf_type_is_func(dtor_func)) + return -EINVAL; + + dtor_func_proto = btf_type_by_id(btf, dtor_func->type); + if (!dtor_func_proto || !btf_type_is_func_proto(dtor_func_proto)) + return -EINVAL; + + /* Make sure the prototype of the destructor kfunc is 'void func(type *)' */ + t = btf_type_by_id(btf, dtor_func_proto->type); + if (!t || !btf_type_is_void(t)) + return -EINVAL; + + nr_args = btf_type_vlen(dtor_func_proto); + if (nr_args != 1) + return -EINVAL; + args = btf_params(dtor_func_proto); + t = btf_type_by_id(btf, args[0].type); + /* Allow any pointer type, as width on targets Linux supports + * will be same for all pointer types (i.e. sizeof(void *)) + */ + if (!t || !btf_type_is_ptr(t)) + return -EINVAL; + } + return 0; +} + +/* This function must be invoked only from initcalls/module init functions */ +int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_cnt, + struct module *owner) +{ + struct btf_id_dtor_kfunc_tab *tab; + struct btf *btf; + u32 tab_cnt; + int ret; + + btf = btf_get_module_btf(owner); + if (!btf) { + if (!owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) { + pr_err("missing vmlinux BTF, cannot register dtor kfuncs\n"); + return -ENOENT; + } + if (owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) { + pr_err("missing module BTF, cannot register dtor kfuncs\n"); + return -ENOENT; + } + return 0; + } + if (IS_ERR(btf)) + return PTR_ERR(btf); + + if (add_cnt >= BTF_DTOR_KFUNC_MAX_CNT) { + pr_err("cannot register more than %d kfunc destructors\n", BTF_DTOR_KFUNC_MAX_CNT); + ret = -E2BIG; + goto end; + } + + /* Ensure that the prototype of dtor kfuncs being registered is sane */ + ret = btf_check_dtor_kfuncs(btf, dtors, add_cnt); + if (ret < 0) + goto end; + + tab = btf->dtor_kfunc_tab; + /* Only one call allowed for modules */ + if (WARN_ON_ONCE(tab && btf_is_module(btf))) { + ret = -EINVAL; + goto end; + } + + tab_cnt = tab ? tab->cnt : 0; + if (tab_cnt > U32_MAX - add_cnt) { + ret = -EOVERFLOW; + goto end; + } + if (tab_cnt + add_cnt >= BTF_DTOR_KFUNC_MAX_CNT) { + pr_err("cannot register more than %d kfunc destructors\n", BTF_DTOR_KFUNC_MAX_CNT); + ret = -E2BIG; + goto end; + } + + tab = krealloc(btf->dtor_kfunc_tab, + offsetof(struct btf_id_dtor_kfunc_tab, dtors[tab_cnt + add_cnt]), + GFP_KERNEL | __GFP_NOWARN); + if (!tab) { + ret = -ENOMEM; + goto end; + } + + if (!btf->dtor_kfunc_tab) + tab->cnt = 0; + btf->dtor_kfunc_tab = tab; + + memcpy(tab->dtors + tab->cnt, dtors, add_cnt * sizeof(tab->dtors[0])); + tab->cnt += add_cnt; + + sort(tab->dtors, tab->cnt, sizeof(tab->dtors[0]), btf_id_cmp_func, NULL); + + return 0; +end: + btf_free_dtor_kfunc_tab(btf); + btf_put(btf); + return ret; +} +EXPORT_SYMBOL_GPL(register_btf_id_dtor_kfuncs); + +#define MAX_TYPES_ARE_COMPAT_DEPTH 2 + +/* Check local and target types for compatibility. This check is used for + * type-based CO-RE relocations and follow slightly different rules than + * field-based relocations. This function assumes that root types were already + * checked for name match. Beyond that initial root-level name check, names + * are completely ignored. Compatibility rules are as follows: + * - any two STRUCTs/UNIONs/FWDs/ENUMs/INTs/ENUM64s are considered compatible, but + * kind should match for local and target types (i.e., STRUCT is not + * compatible with UNION); + * - for ENUMs/ENUM64s, the size is ignored; + * - for INT, size and signedness are ignored; + * - for ARRAY, dimensionality is ignored, element types are checked for + * compatibility recursively; + * - CONST/VOLATILE/RESTRICT modifiers are ignored; + * - TYPEDEFs/PTRs are compatible if types they pointing to are compatible; + * - FUNC_PROTOs are compatible if they have compatible signature: same + * number of input args and compatible return and argument types. + * These rules are not set in stone and probably will be adjusted as we get + * more experience with using BPF CO-RE relocations. + */ +int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id, + const struct btf *targ_btf, __u32 targ_id) +{ + return __bpf_core_types_are_compat(local_btf, local_id, targ_btf, targ_id, + MAX_TYPES_ARE_COMPAT_DEPTH); +} + +#define MAX_TYPES_MATCH_DEPTH 2 + +int bpf_core_types_match(const struct btf *local_btf, u32 local_id, + const struct btf *targ_btf, u32 targ_id) +{ + return __bpf_core_types_match(local_btf, local_id, targ_btf, targ_id, false, + MAX_TYPES_MATCH_DEPTH); } -#define DEFINE_KFUNC_BTF_ID_LIST(name) \ - struct kfunc_btf_id_list name = { LIST_HEAD_INIT(name.list), \ - __MUTEX_INITIALIZER(name.mutex) }; \ - EXPORT_SYMBOL_GPL(name) +static bool bpf_core_is_flavor_sep(const char *s) +{ + /* check X___Y name pattern, where X and Y are not underscores */ + return s[0] != '_' && /* X */ + s[1] == '_' && s[2] == '_' && s[3] == '_' && /* ___ */ + s[4] != '_'; /* Y */ +} + +size_t bpf_core_essential_name_len(const char *name) +{ + size_t n = strlen(name); + int i; -DEFINE_KFUNC_BTF_ID_LIST(bpf_tcp_ca_kfunc_list); -DEFINE_KFUNC_BTF_ID_LIST(prog_test_kfunc_list); + for (i = n - 5; i >= 0; i--) { + if (bpf_core_is_flavor_sep(name + i)) + return i + 1; + } + return n; +} + +struct bpf_cand_cache { + const char *name; + u32 name_len; + u16 kind; + u16 cnt; + struct { + const struct btf *btf; + u32 id; + } cands[]; +}; + +static void bpf_free_cands(struct bpf_cand_cache *cands) +{ + if (!cands->cnt) + /* empty candidate array was allocated on stack */ + return; + kfree(cands); +} + +static void bpf_free_cands_from_cache(struct bpf_cand_cache *cands) +{ + kfree(cands->name); + kfree(cands); +} + +#define VMLINUX_CAND_CACHE_SIZE 31 +static struct bpf_cand_cache *vmlinux_cand_cache[VMLINUX_CAND_CACHE_SIZE]; + +#define MODULE_CAND_CACHE_SIZE 31 +static struct bpf_cand_cache *module_cand_cache[MODULE_CAND_CACHE_SIZE]; + +static DEFINE_MUTEX(cand_cache_mutex); + +static void __print_cand_cache(struct bpf_verifier_log *log, + struct bpf_cand_cache **cache, + int cache_size) +{ + struct bpf_cand_cache *cc; + int i, j; + + for (i = 0; i < cache_size; i++) { + cc = cache[i]; + if (!cc) + continue; + bpf_log(log, "[%d]%s(", i, cc->name); + for (j = 0; j < cc->cnt; j++) { + bpf_log(log, "%d", cc->cands[j].id); + if (j < cc->cnt - 1) + bpf_log(log, " "); + } + bpf_log(log, "), "); + } +} + +static void print_cand_cache(struct bpf_verifier_log *log) +{ + mutex_lock(&cand_cache_mutex); + bpf_log(log, "vmlinux_cand_cache:"); + __print_cand_cache(log, vmlinux_cand_cache, VMLINUX_CAND_CACHE_SIZE); + bpf_log(log, "\nmodule_cand_cache:"); + __print_cand_cache(log, module_cand_cache, MODULE_CAND_CACHE_SIZE); + bpf_log(log, "\n"); + mutex_unlock(&cand_cache_mutex); +} + +static u32 hash_cands(struct bpf_cand_cache *cands) +{ + return jhash(cands->name, cands->name_len, 0); +} + +static struct bpf_cand_cache *check_cand_cache(struct bpf_cand_cache *cands, + struct bpf_cand_cache **cache, + int cache_size) +{ + struct bpf_cand_cache *cc = cache[hash_cands(cands) % cache_size]; + if (cc && cc->name_len == cands->name_len && + !strncmp(cc->name, cands->name, cands->name_len)) + return cc; + return NULL; +} + +static size_t sizeof_cands(int cnt) +{ + return offsetof(struct bpf_cand_cache, cands[cnt]); +} + +static struct bpf_cand_cache *populate_cand_cache(struct bpf_cand_cache *cands, + struct bpf_cand_cache **cache, + int cache_size) +{ + struct bpf_cand_cache **cc = &cache[hash_cands(cands) % cache_size], *new_cands; + + if (*cc) { + bpf_free_cands_from_cache(*cc); + *cc = NULL; + } + new_cands = kmemdup(cands, sizeof_cands(cands->cnt), GFP_KERNEL); + if (!new_cands) { + bpf_free_cands(cands); + return ERR_PTR(-ENOMEM); + } + /* strdup the name, since it will stay in cache. + * the cands->name points to strings in prog's BTF and the prog can be unloaded. + */ + new_cands->name = kmemdup_nul(cands->name, cands->name_len, GFP_KERNEL); + bpf_free_cands(cands); + if (!new_cands->name) { + kfree(new_cands); + return ERR_PTR(-ENOMEM); + } + *cc = new_cands; + return new_cands; +} + +#ifdef CONFIG_DEBUG_INFO_BTF_MODULES +static void __purge_cand_cache(struct btf *btf, struct bpf_cand_cache **cache, + int cache_size) +{ + struct bpf_cand_cache *cc; + int i, j; + + for (i = 0; i < cache_size; i++) { + cc = cache[i]; + if (!cc) + continue; + if (!btf) { + /* when new module is loaded purge all of module_cand_cache, + * since new module might have candidates with the name + * that matches cached cands. + */ + bpf_free_cands_from_cache(cc); + cache[i] = NULL; + continue; + } + /* when module is unloaded purge cache entries + * that match module's btf + */ + for (j = 0; j < cc->cnt; j++) + if (cc->cands[j].btf == btf) { + bpf_free_cands_from_cache(cc); + cache[i] = NULL; + break; + } + } + +} + +static void purge_cand_cache(struct btf *btf) +{ + mutex_lock(&cand_cache_mutex); + __purge_cand_cache(btf, module_cand_cache, MODULE_CAND_CACHE_SIZE); + mutex_unlock(&cand_cache_mutex); +} #endif + +static struct bpf_cand_cache * +bpf_core_add_cands(struct bpf_cand_cache *cands, const struct btf *targ_btf, + int targ_start_id) +{ + struct bpf_cand_cache *new_cands; + const struct btf_type *t; + const char *targ_name; + size_t targ_essent_len; + int n, i; + + n = btf_nr_types(targ_btf); + for (i = targ_start_id; i < n; i++) { + t = btf_type_by_id(targ_btf, i); + if (btf_kind(t) != cands->kind) + continue; + + targ_name = btf_name_by_offset(targ_btf, t->name_off); + if (!targ_name) + continue; + + /* the resched point is before strncmp to make sure that search + * for non-existing name will have a chance to schedule(). + */ + cond_resched(); + + if (strncmp(cands->name, targ_name, cands->name_len) != 0) + continue; + + targ_essent_len = bpf_core_essential_name_len(targ_name); + if (targ_essent_len != cands->name_len) + continue; + + /* most of the time there is only one candidate for a given kind+name pair */ + new_cands = kmalloc(sizeof_cands(cands->cnt + 1), GFP_KERNEL); + if (!new_cands) { + bpf_free_cands(cands); + return ERR_PTR(-ENOMEM); + } + + memcpy(new_cands, cands, sizeof_cands(cands->cnt)); + bpf_free_cands(cands); + cands = new_cands; + cands->cands[cands->cnt].btf = targ_btf; + cands->cands[cands->cnt].id = i; + cands->cnt++; + } + return cands; +} + +static struct bpf_cand_cache * +bpf_core_find_cands(struct bpf_core_ctx *ctx, u32 local_type_id) +{ + struct bpf_cand_cache *cands, *cc, local_cand = {}; + const struct btf *local_btf = ctx->btf; + const struct btf_type *local_type; + const struct btf *main_btf; + size_t local_essent_len; + struct btf *mod_btf; + const char *name; + int id; + + main_btf = bpf_get_btf_vmlinux(); + if (IS_ERR(main_btf)) + return ERR_CAST(main_btf); + if (!main_btf) + return ERR_PTR(-EINVAL); + + local_type = btf_type_by_id(local_btf, local_type_id); + if (!local_type) + return ERR_PTR(-EINVAL); + + name = btf_name_by_offset(local_btf, local_type->name_off); + if (str_is_empty(name)) + return ERR_PTR(-EINVAL); + local_essent_len = bpf_core_essential_name_len(name); + + cands = &local_cand; + cands->name = name; + cands->kind = btf_kind(local_type); + cands->name_len = local_essent_len; + + cc = check_cand_cache(cands, vmlinux_cand_cache, VMLINUX_CAND_CACHE_SIZE); + /* cands is a pointer to stack here */ + if (cc) { + if (cc->cnt) + return cc; + goto check_modules; + } + + /* Attempt to find target candidates in vmlinux BTF first */ + cands = bpf_core_add_cands(cands, main_btf, 1); + if (IS_ERR(cands)) + return ERR_CAST(cands); + + /* cands is a pointer to kmalloced memory here if cands->cnt > 0 */ + + /* populate cache even when cands->cnt == 0 */ + cc = populate_cand_cache(cands, vmlinux_cand_cache, VMLINUX_CAND_CACHE_SIZE); + if (IS_ERR(cc)) + return ERR_CAST(cc); + + /* if vmlinux BTF has any candidate, don't go for module BTFs */ + if (cc->cnt) + return cc; + +check_modules: + /* cands is a pointer to stack here and cands->cnt == 0 */ + cc = check_cand_cache(cands, module_cand_cache, MODULE_CAND_CACHE_SIZE); + if (cc) + /* if cache has it return it even if cc->cnt == 0 */ + return cc; + + /* If candidate is not found in vmlinux's BTF then search in module's BTFs */ + spin_lock_bh(&btf_idr_lock); + idr_for_each_entry(&btf_idr, mod_btf, id) { + if (!btf_is_module(mod_btf)) + continue; + /* linear search could be slow hence unlock/lock + * the IDR to avoiding holding it for too long + */ + btf_get(mod_btf); + spin_unlock_bh(&btf_idr_lock); + cands = bpf_core_add_cands(cands, mod_btf, btf_nr_types(main_btf)); + if (IS_ERR(cands)) { + btf_put(mod_btf); + return ERR_CAST(cands); + } + spin_lock_bh(&btf_idr_lock); + btf_put(mod_btf); + } + spin_unlock_bh(&btf_idr_lock); + /* cands is a pointer to kmalloced memory here if cands->cnt > 0 + * or pointer to stack if cands->cnd == 0. + * Copy it into the cache even when cands->cnt == 0 and + * return the result. + */ + return populate_cand_cache(cands, module_cand_cache, MODULE_CAND_CACHE_SIZE); +} + +int bpf_core_apply(struct bpf_core_ctx *ctx, const struct bpf_core_relo *relo, + int relo_idx, void *insn) +{ + bool need_cands = relo->kind != BPF_CORE_TYPE_ID_LOCAL; + struct bpf_core_cand_list cands = {}; + struct bpf_core_relo_res targ_res; + struct bpf_core_spec *specs; + int err; + + /* ~4k of temp memory necessary to convert LLVM spec like "0:1:0:5" + * into arrays of btf_ids of struct fields and array indices. + */ + specs = kcalloc(3, sizeof(*specs), GFP_KERNEL); + if (!specs) + return -ENOMEM; + + if (need_cands) { + struct bpf_cand_cache *cc; + int i; + + mutex_lock(&cand_cache_mutex); + cc = bpf_core_find_cands(ctx, relo->type_id); + if (IS_ERR(cc)) { + bpf_log(ctx->log, "target candidate search failed for %d\n", + relo->type_id); + err = PTR_ERR(cc); + goto out; + } + if (cc->cnt) { + cands.cands = kcalloc(cc->cnt, sizeof(*cands.cands), GFP_KERNEL); + if (!cands.cands) { + err = -ENOMEM; + goto out; + } + } + for (i = 0; i < cc->cnt; i++) { + bpf_log(ctx->log, + "CO-RE relocating %s %s: found target candidate [%d]\n", + btf_kind_str[cc->kind], cc->name, cc->cands[i].id); + cands.cands[i].btf = cc->cands[i].btf; + cands.cands[i].id = cc->cands[i].id; + } + cands.len = cc->cnt; + /* cand_cache_mutex needs to span the cache lookup and + * copy of btf pointer into bpf_core_cand_list, + * since module can be unloaded while bpf_core_calc_relo_insn + * is working with module's btf. + */ + } + + err = bpf_core_calc_relo_insn((void *)ctx->log, relo, relo_idx, ctx->btf, &cands, specs, + &targ_res); + if (err) + goto out; + + err = bpf_core_patch_insn((void *)ctx->log, insn, relo->insn_off / 8, relo, relo_idx, + &targ_res); + +out: + kfree(specs); + if (need_cands) { + kfree(cands.cands); + mutex_unlock(&cand_cache_mutex); + if (ctx->log->level & BPF_LOG_LEVEL2) + print_cand_cache(ctx->log); + } + return err; +} |