Remove duplicated BTF parsing logic when it comes to subprog call check.
Instead, use (potentially cached) results of btf_prepare_func_args() to
abstract away expectations of each subprog argument in generic terms
(e.g., "this is pointer to context", or "this is a pointer to memory of
size X"), and then use those simple high-level argument type
expectations to validate actual register states to check if they match
expectations.
Acked-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
kernel/bpf/verifier.c | 110 +++++-------------
.../selftests/bpf/progs/test_global_func5.c | 2 +-
2 files changed, 31 insertions(+), 81 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index b5237ddb00bf..612e76a1034d 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -9256,101 +9256,54 @@ static int setup_func_entry(struct bpf_verifier_env *env, int subprog, int calls
return err;
}
-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)
+static int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog,
+ const struct btf *btf,
+ struct bpf_reg_state *regs)
{
- enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
+ struct bpf_subprog_info *sub = subprog_info(env, subprog);
struct bpf_verifier_log *log = &env->log;
- const char *func_name, *ref_tname;
- const struct btf_type *t, *ref_t;
- const struct btf_param *args;
- u32 i, nargs, ref_id;
+ u32 i;
int ret;
- t = btf_type_by_id(btf, func_id);
- if (!t || !btf_type_is_func(t)) {
- /* These checks were already done by the verifier while loading
- * struct bpf_func_info or in add_kfunc_call().
- */
- bpf_log(log, "BTF of func_id %u doesn't point to KIND_FUNC\n",
- func_id);
- return -EFAULT;
- }
- func_name = btf_name_by_offset(btf, t->name_off);
-
- t = btf_type_by_id(btf, t->type);
- if (!t || !btf_type_is_func_proto(t)) {
- bpf_log(log, "Invalid BTF of func %s\n", func_name);
- return -EFAULT;
- }
- args = (const struct btf_param *)(t + 1);
- nargs = btf_type_vlen(t);
- if (nargs > MAX_BPF_FUNC_REG_ARGS) {
- bpf_log(log, "Function %s has %d > %d args\n", func_name, nargs,
- MAX_BPF_FUNC_REG_ARGS);
- return -EINVAL;
- }
+ ret = btf_prepare_func_args(env, subprog);
+ if (ret)
+ return ret;
/* 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;
+ for (i = 0; i < sub->arg_cnt; i++) {
u32 regno = i + 1;
struct bpf_reg_state *reg = ®s[regno];
+ struct bpf_subprog_arg_info *arg = &sub->args[i];
- t = btf_type_skip_modifiers(btf, args[i].type, NULL);
- if (btf_type_is_scalar(t)) {
- if (reg->type == SCALAR_VALUE)
- continue;
- bpf_log(log, "R%d is not a scalar\n", regno);
- return -EINVAL;
- }
-
- if (!btf_type_is_ptr(t)) {
- bpf_log(log, "Unrecognized arg#%d type %s\n",
- i, btf_type_str(t));
- return -EINVAL;
- }
-
- ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id);
- ref_tname = btf_name_by_offset(btf, ref_t->name_off);
-
- ret = check_func_arg_reg_off(env, reg, regno, arg_type);
- if (ret < 0)
- return ret;
-
- if (btf_get_prog_ctx_type(log, btf, t, prog_type, i)) {
+ if (arg->arg_type == ARG_ANYTHING) {
+ if (reg->type != SCALAR_VALUE) {
+ bpf_log(log, "R%d is not a scalar\n", regno);
+ return -EINVAL;
+ }
+ } else if (arg->arg_type == ARG_PTR_TO_CTX) {
+ ret = check_func_arg_reg_off(env, reg, regno, ARG_DONTCARE);
+ if (ret < 0)
+ return ret;
/* 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 (ptr_to_mem_ok) {
- const struct btf_type *resolve_ret;
- u32 type_size;
-
- resolve_ret = btf_resolve_size(btf, ref_t, &type_size);
- if (IS_ERR(resolve_ret)) {
- bpf_log(log,
- "arg#%d reference type('%s %s') size cannot be determined: %ld\n",
- i, btf_type_str(ref_t), ref_tname,
- PTR_ERR(resolve_ret));
+ bpf_log(log, "arg#%d expects pointer to ctx\n", i);
return -EINVAL;
}
+ } else if (base_type(arg->arg_type) == ARG_PTR_TO_MEM) {
+ ret = check_func_arg_reg_off(env, reg, regno, ARG_DONTCARE);
+ if (ret < 0)
+ return ret;
- if (check_mem_reg(env, reg, regno, type_size))
+ if (check_mem_reg(env, reg, regno, arg->mem_size))
return -EINVAL;
} else {
- bpf_log(log, "reg type unsupported for arg#%d function %s#%d\n", i,
- func_name, func_id);
- return -EINVAL;
+ bpf_log(log, "verifier bug: unrecognized arg#%d type %d\n",
+ i, arg->arg_type);
+ return -EFAULT;
}
}
@@ -9365,11 +9318,10 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env,
* Only PTR_TO_CTX and SCALAR_VALUE states are recognized.
*/
static int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog,
- struct bpf_reg_state *regs)
+ 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;
@@ -9383,9 +9335,7 @@ static int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog,
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);
-
+ err = btf_check_func_arg_match(env, subprog, btf, regs);
/* 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.
diff --git a/tools/testing/selftests/bpf/progs/test_global_func5.c b/tools/testing/selftests/bpf/progs/test_global_func5.c
index cc55aedaf82d..257c0569ff98 100644
--- a/tools/testing/selftests/bpf/progs/test_global_func5.c
+++ b/tools/testing/selftests/bpf/progs/test_global_func5.c
@@ -26,7 +26,7 @@ int f3(int val, struct __sk_buff *skb)
}
SEC("tc")
-__failure __msg("expected pointer to ctx, but got PTR")
+__failure __msg("expects pointer to ctx")
int global_func5(struct __sk_buff *skb)
{
return f1(skb) + f2(2, skb) + f3(3, skb);
--
2.34.1
