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Diffstat (limited to 'kernel/bpf/verifier.c')
-rw-r--r--kernel/bpf/verifier.c98
1 files changed, 72 insertions, 26 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 6a936159c6e0..8740c5fa02fc 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -19,6 +19,7 @@
#include <net/netlink.h>
#include <linux/file.h>
#include <linux/vmalloc.h>
+#include <linux/stringify.h>
/* bpf_check() is a static code analyzer that walks eBPF program
* instruction by instruction and updates register/stack state.
@@ -190,6 +191,22 @@ static const char * const reg_type_str[] = {
[PTR_TO_PACKET_END] = "pkt_end",
};
+#define __BPF_FUNC_STR_FN(x) [BPF_FUNC_ ## x] = __stringify(bpf_ ## x)
+static const char * const func_id_str[] = {
+ __BPF_FUNC_MAPPER(__BPF_FUNC_STR_FN)
+};
+#undef __BPF_FUNC_STR_FN
+
+static const char *func_id_name(int id)
+{
+ BUILD_BUG_ON(ARRAY_SIZE(func_id_str) != __BPF_FUNC_MAX_ID);
+
+ if (id >= 0 && id < __BPF_FUNC_MAX_ID && func_id_str[id])
+ return func_id_str[id];
+ else
+ return "unknown";
+}
+
static void print_verifier_state(struct bpf_verifier_state *state)
{
struct bpf_reg_state *reg;
@@ -212,9 +229,10 @@ static void print_verifier_state(struct bpf_verifier_state *state)
else if (t == CONST_PTR_TO_MAP || t == PTR_TO_MAP_VALUE ||
t == PTR_TO_MAP_VALUE_OR_NULL ||
t == PTR_TO_MAP_VALUE_ADJ)
- verbose("(ks=%d,vs=%d)",
+ verbose("(ks=%d,vs=%d,id=%u)",
reg->map_ptr->key_size,
- reg->map_ptr->value_size);
+ reg->map_ptr->value_size,
+ reg->id);
if (reg->min_value != BPF_REGISTER_MIN_RANGE)
verbose(",min_value=%lld",
(long long)reg->min_value);
@@ -353,7 +371,8 @@ static void print_bpf_insn(struct bpf_insn *insn)
u8 opcode = BPF_OP(insn->code);
if (opcode == BPF_CALL) {
- verbose("(%02x) call %d\n", insn->code, insn->imm);
+ verbose("(%02x) call %s#%d\n", insn->code,
+ func_id_name(insn->imm), insn->imm);
} else if (insn->code == (BPF_JMP | BPF_JA)) {
verbose("(%02x) goto pc%+d\n",
insn->code, insn->off);
@@ -447,6 +466,7 @@ static void mark_reg_unknown_value(struct bpf_reg_state *regs, u32 regno)
{
BUG_ON(regno >= MAX_BPF_REG);
regs[regno].type = UNKNOWN_VALUE;
+ regs[regno].id = 0;
regs[regno].imm = 0;
}
@@ -1112,8 +1132,8 @@ static int check_map_func_compatibility(struct bpf_map *map, int func_id)
return 0;
error:
- verbose("cannot pass map_type %d into func %d\n",
- map->map_type, func_id);
+ verbose("cannot pass map_type %d into func %s#%d\n",
+ map->map_type, func_id_name(func_id), func_id);
return -EINVAL;
}
@@ -1170,7 +1190,7 @@ static int check_call(struct bpf_verifier_env *env, int func_id)
/* find function prototype */
if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) {
- verbose("invalid func %d\n", func_id);
+ verbose("invalid func %s#%d\n", func_id_name(func_id), func_id);
return -EINVAL;
}
@@ -1178,7 +1198,7 @@ static int check_call(struct bpf_verifier_env *env, int func_id)
fn = env->prog->aux->ops->get_func_proto(func_id);
if (!fn) {
- verbose("unknown func %d\n", func_id);
+ verbose("unknown func %s#%d\n", func_id_name(func_id), func_id);
return -EINVAL;
}
@@ -1198,7 +1218,8 @@ static int check_call(struct bpf_verifier_env *env, int func_id)
*/
err = check_raw_mode(fn);
if (err) {
- verbose("kernel subsystem misconfigured func %d\n", func_id);
+ verbose("kernel subsystem misconfigured func %s#%d\n",
+ func_id_name(func_id), func_id);
return err;
}
@@ -1252,9 +1273,10 @@ static int check_call(struct bpf_verifier_env *env, int func_id)
return -EINVAL;
}
regs[BPF_REG_0].map_ptr = meta.map_ptr;
+ regs[BPF_REG_0].id = ++env->id_gen;
} else {
- verbose("unknown return type %d of func %d\n",
- fn->ret_type, func_id);
+ verbose("unknown return type %d of func %s#%d\n",
+ fn->ret_type, func_id_name(func_id), func_id);
return -EINVAL;
}
@@ -1479,7 +1501,6 @@ static void adjust_reg_min_max_vals(struct bpf_verifier_env *env,
struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg;
s64 min_val = BPF_REGISTER_MIN_RANGE;
u64 max_val = BPF_REGISTER_MAX_RANGE;
- bool min_set = false, max_set = false;
u8 opcode = BPF_OP(insn->code);
dst_reg = &regs[insn->dst_reg];
@@ -1502,7 +1523,6 @@ static void adjust_reg_min_max_vals(struct bpf_verifier_env *env,
} else if (insn->imm < BPF_REGISTER_MAX_RANGE &&
(s64)insn->imm > BPF_REGISTER_MIN_RANGE) {
min_val = max_val = insn->imm;
- min_set = max_set = true;
}
/* We don't know anything about what was done to this register, mark it
@@ -1668,8 +1688,7 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
insn->src_reg);
return -EACCES;
}
- regs[insn->dst_reg].type = UNKNOWN_VALUE;
- regs[insn->dst_reg].map_ptr = NULL;
+ mark_reg_unknown_value(regs, insn->dst_reg);
}
} else {
/* case: R = imm
@@ -1931,6 +1950,38 @@ static void reg_set_min_max_inv(struct bpf_reg_state *true_reg,
check_reg_overflow(true_reg);
}
+static void mark_map_reg(struct bpf_reg_state *regs, u32 regno, u32 id,
+ enum bpf_reg_type type)
+{
+ struct bpf_reg_state *reg = &regs[regno];
+
+ if (reg->type == PTR_TO_MAP_VALUE_OR_NULL && reg->id == id) {
+ reg->type = type;
+ if (type == UNKNOWN_VALUE)
+ mark_reg_unknown_value(regs, regno);
+ }
+}
+
+/* The logic is similar to find_good_pkt_pointers(), both could eventually
+ * be folded together at some point.
+ */
+static void mark_map_regs(struct bpf_verifier_state *state, u32 regno,
+ enum bpf_reg_type type)
+{
+ struct bpf_reg_state *regs = state->regs;
+ int i;
+
+ for (i = 0; i < MAX_BPF_REG; i++)
+ mark_map_reg(regs, i, regs[regno].id, type);
+
+ for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
+ if (state->stack_slot_type[i] != STACK_SPILL)
+ continue;
+ mark_map_reg(state->spilled_regs, i / BPF_REG_SIZE,
+ regs[regno].id, type);
+ }
+}
+
static int check_cond_jmp_op(struct bpf_verifier_env *env,
struct bpf_insn *insn, int *insn_idx)
{
@@ -2018,18 +2069,13 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env,
if (BPF_SRC(insn->code) == BPF_K &&
insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) &&
dst_reg->type == PTR_TO_MAP_VALUE_OR_NULL) {
- if (opcode == BPF_JEQ) {
- /* next fallthrough insn can access memory via
- * this register
- */
- regs[insn->dst_reg].type = PTR_TO_MAP_VALUE;
- /* branch targer cannot access it, since reg == 0 */
- mark_reg_unknown_value(other_branch->regs,
- insn->dst_reg);
- } else {
- other_branch->regs[insn->dst_reg].type = PTR_TO_MAP_VALUE;
- mark_reg_unknown_value(regs, insn->dst_reg);
- }
+ /* Mark all identical map registers in each branch as either
+ * safe or unknown depending R == 0 or R != 0 conditional.
+ */
+ mark_map_regs(this_branch, insn->dst_reg,
+ opcode == BPF_JEQ ? PTR_TO_MAP_VALUE : UNKNOWN_VALUE);
+ mark_map_regs(other_branch, insn->dst_reg,
+ opcode == BPF_JEQ ? UNKNOWN_VALUE : PTR_TO_MAP_VALUE);
} else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT &&
dst_reg->type == PTR_TO_PACKET &&
regs[insn->src_reg].type == PTR_TO_PACKET_END) {
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.