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bpf: adjust insn_aux_data when patching insns

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convert_ctx_accesses() replaces single bpf instruction with a set of
instructions. Adjust corresponding insn_aux_data while patching.
It's needed to make sure subsequent 'for(all insn)' loops
have matching insn and insn_aux_data.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov 2017-03-15 18:26:41 -07:00 committed by David S. Miller
parent 79741b3bde
commit 8041902dae
1 changed files with 39 additions and 5 deletions
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44
kernel/bpf/verifier.c
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@ -3162,6 +3162,41 @@ static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env)
insn->src_reg = 0; insn->src_reg = 0;
} }
/* single env->prog->insni[off] instruction was replaced with the range
* insni[off, off + cnt). Adjust corresponding insn_aux_data by copying
* [0, off) and [off, end) to new locations, so the patched range stays zero
*/
static int adjust_insn_aux_data(struct bpf_verifier_env *env, u32 prog_len,
u32 off, u32 cnt)
{
struct bpf_insn_aux_data *new_data, *old_data = env->insn_aux_data;
if (cnt == 1)
return 0;
new_data = vzalloc(sizeof(struct bpf_insn_aux_data) * prog_len);
if (!new_data)
return -ENOMEM;
memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off);
memcpy(new_data + off + cnt - 1, old_data + off,
sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1));
env->insn_aux_data = new_data;
vfree(old_data);
return 0;
}
static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off,
const struct bpf_insn *patch, u32 len)
{
struct bpf_prog *new_prog;
new_prog = bpf_patch_insn_single(env->prog, off, patch, len);
if (!new_prog)
return NULL;
if (adjust_insn_aux_data(env, new_prog->len, off, len))
return NULL;
return new_prog;
}
/* convert load instructions that access fields of 'struct __sk_buff' /* convert load instructions that access fields of 'struct __sk_buff'
* into sequence of instructions that access fields of 'struct sk_buff' * into sequence of instructions that access fields of 'struct sk_buff'
*/ */
@ -3181,10 +3216,10 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
verbose("bpf verifier is misconfigured\n"); verbose("bpf verifier is misconfigured\n");
return -EINVAL; return -EINVAL;
} else if (cnt) { } else if (cnt) {
new_prog = bpf_patch_insn_single(env->prog, 0, new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt);
insn_buf, cnt);
if (!new_prog) if (!new_prog)
return -ENOMEM; return -ENOMEM;
env->prog = new_prog; env->prog = new_prog;
delta += cnt - 1; delta += cnt - 1;
} }
@ -3209,7 +3244,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
else else
continue; continue;
if (env->insn_aux_data[i].ptr_type != PTR_TO_CTX) if (env->insn_aux_data[i + delta].ptr_type != PTR_TO_CTX)
continue; continue;
cnt = ops->convert_ctx_access(type, insn, insn_buf, env->prog); cnt = ops->convert_ctx_access(type, insn, insn_buf, env->prog);
@ -3218,8 +3253,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
return -EINVAL; return -EINVAL;
} }
new_prog = bpf_patch_insn_single(env->prog, i + delta, insn_buf, new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
cnt);
if (!new_prog) if (!new_prog)
return -ENOMEM; return -ENOMEM;