summaryrefslogtreecommitdiff
path: root/kernel/bpf/verifier.c
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/bpf/verifier.c')
-rw-r--r--kernel/bpf/verifier.c152
1 files changed, 136 insertions, 16 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index e6b522496250..c22ebd36fa4b 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1620,11 +1620,10 @@ static int do_check(struct verifier_env *env)
return err;
} else if (class == BPF_LDX) {
- if (BPF_MODE(insn->code) != BPF_MEM ||
- insn->imm != 0) {
- verbose("BPF_LDX uses reserved fields\n");
- return -EINVAL;
- }
+ enum bpf_reg_type src_reg_type;
+
+ /* check for reserved fields is already done */
+
/* check src operand */
err = check_reg_arg(regs, insn->src_reg, SRC_OP);
if (err)
@@ -1643,6 +1642,29 @@ static int do_check(struct verifier_env *env)
if (err)
return err;
+ src_reg_type = regs[insn->src_reg].type;
+
+ if (insn->imm == 0 && BPF_SIZE(insn->code) == BPF_W) {
+ /* saw a valid insn
+ * dst_reg = *(u32 *)(src_reg + off)
+ * use reserved 'imm' field to mark this insn
+ */
+ insn->imm = src_reg_type;
+
+ } else if (src_reg_type != insn->imm &&
+ (src_reg_type == PTR_TO_CTX ||
+ insn->imm == PTR_TO_CTX)) {
+ /* ABuser program is trying to use the same insn
+ * dst_reg = *(u32*) (src_reg + off)
+ * with different pointer types:
+ * src_reg == ctx in one branch and
+ * src_reg == stack|map in some other branch.
+ * Reject it.
+ */
+ verbose("same insn cannot be used with different pointers\n");
+ return -EINVAL;
+ }
+
} else if (class == BPF_STX) {
if (BPF_MODE(insn->code) == BPF_XADD) {
err = check_xadd(env, insn);
@@ -1790,6 +1812,13 @@ static int replace_map_fd_with_map_ptr(struct verifier_env *env)
int i, j;
for (i = 0; i < insn_cnt; i++, insn++) {
+ if (BPF_CLASS(insn->code) == BPF_LDX &&
+ (BPF_MODE(insn->code) != BPF_MEM ||
+ insn->imm != 0)) {
+ verbose("BPF_LDX uses reserved fields\n");
+ return -EINVAL;
+ }
+
if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
struct bpf_map *map;
struct fd f;
@@ -1881,6 +1910,92 @@ static void convert_pseudo_ld_imm64(struct verifier_env *env)
insn->src_reg = 0;
}
+static void adjust_branches(struct bpf_prog *prog, int pos, int delta)
+{
+ struct bpf_insn *insn = prog->insnsi;
+ int insn_cnt = prog->len;
+ int i;
+
+ for (i = 0; i < insn_cnt; i++, insn++) {
+ if (BPF_CLASS(insn->code) != BPF_JMP ||
+ BPF_OP(insn->code) == BPF_CALL ||
+ BPF_OP(insn->code) == BPF_EXIT)
+ continue;
+
+ /* adjust offset of jmps if necessary */
+ if (i < pos && i + insn->off + 1 > pos)
+ insn->off += delta;
+ else if (i > pos && i + insn->off + 1 < pos)
+ insn->off -= delta;
+ }
+}
+
+/* convert load instructions that access fields of 'struct __sk_buff'
+ * into sequence of instructions that access fields of 'struct sk_buff'
+ */
+static int convert_ctx_accesses(struct verifier_env *env)
+{
+ struct bpf_insn *insn = env->prog->insnsi;
+ int insn_cnt = env->prog->len;
+ struct bpf_insn insn_buf[16];
+ struct bpf_prog *new_prog;
+ u32 cnt;
+ int i;
+
+ if (!env->prog->aux->ops->convert_ctx_access)
+ return 0;
+
+ for (i = 0; i < insn_cnt; i++, insn++) {
+ if (insn->code != (BPF_LDX | BPF_MEM | BPF_W))
+ continue;
+
+ if (insn->imm != PTR_TO_CTX) {
+ /* clear internal mark */
+ insn->imm = 0;
+ continue;
+ }
+
+ cnt = env->prog->aux->ops->
+ convert_ctx_access(insn->dst_reg, insn->src_reg,
+ insn->off, insn_buf);
+ if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
+ verbose("bpf verifier is misconfigured\n");
+ return -EINVAL;
+ }
+
+ if (cnt == 1) {
+ memcpy(insn, insn_buf, sizeof(*insn));
+ continue;
+ }
+
+ /* several new insns need to be inserted. Make room for them */
+ insn_cnt += cnt - 1;
+ new_prog = bpf_prog_realloc(env->prog,
+ bpf_prog_size(insn_cnt),
+ GFP_USER);
+ if (!new_prog)
+ return -ENOMEM;
+
+ new_prog->len = insn_cnt;
+
+ memmove(new_prog->insnsi + i + cnt, new_prog->insns + i + 1,
+ sizeof(*insn) * (insn_cnt - i - cnt));
+
+ /* copy substitute insns in place of load instruction */
+ memcpy(new_prog->insnsi + i, insn_buf, sizeof(*insn) * cnt);
+
+ /* adjust branches in the whole program */
+ adjust_branches(new_prog, i, cnt - 1);
+
+ /* keep walking new program and skip insns we just inserted */
+ env->prog = new_prog;
+ insn = new_prog->insnsi + i + cnt - 1;
+ i += cnt - 1;
+ }
+
+ return 0;
+}
+
static void free_states(struct verifier_env *env)
{
struct verifier_state_list *sl, *sln;
@@ -1903,13 +2018,13 @@ static void free_states(struct verifier_env *env)
kfree(env->explored_states);
}
-int bpf_check(struct bpf_prog *prog, union bpf_attr *attr)
+int bpf_check(struct bpf_prog **prog, union bpf_attr *attr)
{
char __user *log_ubuf = NULL;
struct verifier_env *env;
int ret = -EINVAL;
- if (prog->len <= 0 || prog->len > BPF_MAXINSNS)
+ if ((*prog)->len <= 0 || (*prog)->len > BPF_MAXINSNS)
return -E2BIG;
/* 'struct verifier_env' can be global, but since it's not small,
@@ -1919,7 +2034,7 @@ int bpf_check(struct bpf_prog *prog, union bpf_attr *attr)
if (!env)
return -ENOMEM;
- env->prog = prog;
+ env->prog = *prog;
/* grab the mutex to protect few globals used by verifier */
mutex_lock(&bpf_verifier_lock);
@@ -1951,7 +2066,7 @@ int bpf_check(struct bpf_prog *prog, union bpf_attr *attr)
if (ret < 0)
goto skip_full_check;
- env->explored_states = kcalloc(prog->len,
+ env->explored_states = kcalloc(env->prog->len,
sizeof(struct verifier_state_list *),
GFP_USER);
ret = -ENOMEM;
@@ -1968,6 +2083,10 @@ skip_full_check:
while (pop_stack(env, NULL) >= 0);
free_states(env);
+ if (ret == 0)
+ /* program is valid, convert *(u32*)(ctx + off) accesses */
+ ret = convert_ctx_accesses(env);
+
if (log_level && log_len >= log_size - 1) {
BUG_ON(log_len >= log_size);
/* verifier log exceeded user supplied buffer */
@@ -1983,18 +2102,18 @@ skip_full_check:
if (ret == 0 && env->used_map_cnt) {
/* if program passed verifier, update used_maps in bpf_prog_info */
- prog->aux->used_maps = kmalloc_array(env->used_map_cnt,
- sizeof(env->used_maps[0]),
- GFP_KERNEL);
+ env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt,
+ sizeof(env->used_maps[0]),
+ GFP_KERNEL);
- if (!prog->aux->used_maps) {
+ if (!env->prog->aux->used_maps) {
ret = -ENOMEM;
goto free_log_buf;
}
- memcpy(prog->aux->used_maps, env->used_maps,
+ memcpy(env->prog->aux->used_maps, env->used_maps,
sizeof(env->used_maps[0]) * env->used_map_cnt);
- prog->aux->used_map_cnt = env->used_map_cnt;
+ env->prog->aux->used_map_cnt = env->used_map_cnt;
/* program is valid. Convert pseudo bpf_ld_imm64 into generic
* bpf_ld_imm64 instructions
@@ -2006,11 +2125,12 @@ free_log_buf:
if (log_level)
vfree(log_buf);
free_env:
- if (!prog->aux->used_maps)
+ if (!env->prog->aux->used_maps)
/* if we didn't copy map pointers into bpf_prog_info, release
* them now. Otherwise free_bpf_prog_info() will release them.
*/
release_maps(env);
+ *prog = env->prog;
kfree(env);
mutex_unlock(&bpf_verifier_lock);
return ret;
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-03 12:39:46 +0000