[PATCH 03/13] bpf: move {prev_,}insn_idx into verifier env
Tyler Hicks
tyhicks at canonical.com
Mon Feb 11 05:25:00 UTC 2019
From: Daniel Borkmann <daniel at iogearbox.net>
Move prev_insn_idx and insn_idx from the do_check() function into
the verifier environment, so they can be read inside the various
helper functions for handling the instructions. It's easier to put
this into the environment rather than changing all call-sites only
to pass it along. insn_idx is useful in particular since this later
on allows to hold state in env->insn_aux_data[env->insn_idx].
Signed-off-by: Daniel Borkmann <daniel at iogearbox.net>
Acked-by: Alexei Starovoitov <ast at kernel.org>
Signed-off-by: Alexei Starovoitov <ast at kernel.org>
CVE-2019-7308
(backported from commit c08435ec7f2bc8f4109401f696fd55159b4b40cb)
[tyhicks: Backport around missing verbose logging message]
[tyhicks: Backport around minor whitespace difference]
[tyhicks: Backport around lack of bpf function call support]
Signed-off-by: Tyler Hicks <tyhicks at canonical.com>
---
include/linux/bpf_verifier.h | 2 ++
kernel/bpf/verifier.c | 67 ++++++++++++++++++++++----------------------
2 files changed, 36 insertions(+), 33 deletions(-)
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index f4a0af1e06fa..70952abb24cb 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -146,6 +146,8 @@ struct bpf_ext_analyzer_ops {
* one verifier_env per bpf_check() call
*/
struct bpf_verifier_env {
+ u32 insn_idx;
+ u32 prev_insn_idx;
struct bpf_prog *prog; /* eBPF program being verified */
const struct bpf_verifier_ops *ops;
struct bpf_verifier_stack_elem *head; /* stack of verifier states to be processed */
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 70497384cf91..52570eaa204f 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3927,7 +3927,6 @@ static int do_check(struct bpf_verifier_env *env)
struct bpf_insn *insns = env->prog->insnsi;
struct bpf_reg_state *regs;
int insn_cnt = env->prog->len;
- int insn_idx, prev_insn_idx = 0;
int insn_processed = 0;
bool do_print_state = false;
@@ -3937,19 +3936,19 @@ static int do_check(struct bpf_verifier_env *env)
env->cur_state = state;
init_reg_state(env, state->regs);
state->parent = NULL;
- insn_idx = 0;
+
for (;;) {
struct bpf_insn *insn;
u8 class;
int err;
- if (insn_idx >= insn_cnt) {
+ if (env->insn_idx >= insn_cnt) {
verbose(env, "invalid insn idx %d insn_cnt %d\n",
- insn_idx, insn_cnt);
+ env->insn_idx, insn_cnt);
return -EFAULT;
}
- insn = &insns[insn_idx];
+ insn = &insns[env->insn_idx];
class = BPF_CLASS(insn->code);
if (++insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) {
@@ -3959,7 +3958,7 @@ static int do_check(struct bpf_verifier_env *env)
return -E2BIG;
}
- err = is_state_visited(env, insn_idx);
+ err = is_state_visited(env, env->insn_idx);
if (err < 0)
return err;
if (err == 1) {
@@ -3967,9 +3966,9 @@ static int do_check(struct bpf_verifier_env *env)
if (env->log.level) {
if (do_print_state)
verbose(env, "\nfrom %d to %d: safe\n",
- prev_insn_idx, insn_idx);
+ env->prev_insn_idx, env->insn_idx);
else
- verbose(env, "%d: safe\n", insn_idx);
+ verbose(env, "%d: safe\n", env->insn_idx);
}
goto process_bpf_exit;
}
@@ -3979,26 +3978,27 @@ static int do_check(struct bpf_verifier_env *env)
if (env->log.level > 1 || (env->log.level && do_print_state)) {
if (env->log.level > 1)
- verbose(env, "%d:", insn_idx);
+ verbose(env, "%d:", env->insn_idx);
else
verbose(env, "\nfrom %d to %d:",
- prev_insn_idx, insn_idx);
+ env->prev_insn_idx, env->insn_idx);
print_verifier_state(env, state);
do_print_state = false;
}
if (env->log.level) {
- verbose(env, "%d: ", insn_idx);
+ verbose(env, "%d: ", env->insn_idx);
print_bpf_insn(verbose, env, insn,
env->allow_ptr_leaks);
}
- err = ext_analyzer_insn_hook(env, insn_idx, prev_insn_idx);
+ err = ext_analyzer_insn_hook(env, env->insn_idx, env->prev_insn_idx);
if (err)
return err;
regs = cur_regs(env);
- env->insn_aux_data[insn_idx].seen = true;
+ env->insn_aux_data[env->insn_idx].seen = true;
+
if (class == BPF_ALU || class == BPF_ALU64) {
err = check_alu_op(env, insn);
if (err)
@@ -4023,13 +4023,13 @@ static int do_check(struct bpf_verifier_env *env)
/* check that memory (src_reg + off) is readable,
* the state of dst_reg will be updated by this func
*/
- err = check_mem_access(env, insn_idx, insn->src_reg, insn->off,
- BPF_SIZE(insn->code), BPF_READ,
- insn->dst_reg, false);
+ err = check_mem_access(env, env->insn_idx, insn->src_reg,
+ insn->off, BPF_SIZE(insn->code),
+ BPF_READ, insn->dst_reg, false);
if (err)
return err;
- prev_src_type = &env->insn_aux_data[insn_idx].ptr_type;
+ prev_src_type = &env->insn_aux_data[env->insn_idx].ptr_type;
if (*prev_src_type == NOT_INIT) {
/* saw a valid insn
@@ -4056,10 +4056,10 @@ static int do_check(struct bpf_verifier_env *env)
enum bpf_reg_type *prev_dst_type, dst_reg_type;
if (BPF_MODE(insn->code) == BPF_XADD) {
- err = check_xadd(env, insn_idx, insn);
+ err = check_xadd(env, env->insn_idx, insn);
if (err)
return err;
- insn_idx++;
+ env->insn_idx++;
continue;
}
@@ -4075,13 +4075,13 @@ static int do_check(struct bpf_verifier_env *env)
dst_reg_type = regs[insn->dst_reg].type;
/* check that memory (dst_reg + off) is writeable */
- err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
- BPF_SIZE(insn->code), BPF_WRITE,
- insn->src_reg, false);
+ err = check_mem_access(env, env->insn_idx, insn->dst_reg,
+ insn->off, BPF_SIZE(insn->code),
+ BPF_WRITE, insn->src_reg, false);
if (err)
return err;
- prev_dst_type = &env->insn_aux_data[insn_idx].ptr_type;
+ prev_dst_type = &env->insn_aux_data[env->insn_idx].ptr_type;
if (*prev_dst_type == NOT_INIT) {
*prev_dst_type = dst_reg_type;
@@ -4110,9 +4110,9 @@ static int do_check(struct bpf_verifier_env *env)
}
/* check that memory (dst_reg + off) is writeable */
- err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
- BPF_SIZE(insn->code), BPF_WRITE,
- -1, false);
+ err = check_mem_access(env, env->insn_idx, insn->dst_reg,
+ insn->off, BPF_SIZE(insn->code),
+ BPF_WRITE, -1, false);
if (err)
return err;
@@ -4128,7 +4128,7 @@ static int do_check(struct bpf_verifier_env *env)
return -EINVAL;
}
- err = check_call(env, insn->imm, insn_idx);
+ err = check_call(env, insn->imm, env->insn_idx);
if (err)
return err;
@@ -4141,7 +4141,7 @@ static int do_check(struct bpf_verifier_env *env)
return -EINVAL;
}
- insn_idx += insn->off + 1;
+ env->insn_idx += insn->off + 1;
continue;
} else if (opcode == BPF_EXIT) {
@@ -4172,7 +4172,8 @@ static int do_check(struct bpf_verifier_env *env)
if (err)
return err;
process_bpf_exit:
- err = pop_stack(env, &prev_insn_idx, &insn_idx);
+ err = pop_stack(env, &env->prev_insn_idx,
+ &env->insn_idx);
if (err < 0) {
if (err != -ENOENT)
return err;
@@ -4182,7 +4183,7 @@ static int do_check(struct bpf_verifier_env *env)
continue;
}
} else {
- err = check_cond_jmp_op(env, insn, &insn_idx);
+ err = check_cond_jmp_op(env, insn, &env->insn_idx);
if (err)
return err;
}
@@ -4199,8 +4200,8 @@ static int do_check(struct bpf_verifier_env *env)
if (err)
return err;
- insn_idx++;
- env->insn_aux_data[insn_idx].seen = true;
+ env->insn_idx++;
+ env->insn_aux_data[env->insn_idx].seen = true;
} else {
verbose(env, "invalid BPF_LD mode\n");
return -EINVAL;
@@ -4210,7 +4211,7 @@ static int do_check(struct bpf_verifier_env *env)
return -EINVAL;
}
- insn_idx++;
+ env->insn_idx++;
}
verbose(env, "processed %d insns, stack depth %d\n", insn_processed,
--
2.7.4
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