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bpf: prepare btf_prepare_func_args() for multiple tags per argument

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Add btf_arg_tag flags enum to be able to record multiple tags per
argument. Also streamline pointer argument processing some more.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240105000909.2818934-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Andrii Nakryiko 2024-01-04 16:09:04 -08:00 committed by Alexei Starovoitov
parent 18810ad392
commit 54c11ec493
2 changed files with 37 additions and 17 deletions
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53
kernel/bpf/btf.c
View file

@ -6946,6 +6946,11 @@ static bool btf_is_dynptr_ptr(const struct btf *btf, const struct btf_type *t)
return false;
}
enum btf_arg_tag {
ARG_TAG_CTX = 0x1,
ARG_TAG_NONNULL = 0x2,
};
/* Process BTF of a function to produce high-level expectation of function
* arguments (like ARG_PTR_TO_CTX, or ARG_PTR_TO_MEM, etc). This information
* is cached in subprog info for reuse.
@ -7027,10 +7032,8 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
* Only PTR_TO_CTX and SCALAR are supported atm.
*/
for (i = 0; i < nargs; i++) {
bool is_nonnull = false;
const char *tag;
t = btf_type_by_id(btf, args[i].type);
u32 tags = 0;
tag = btf_find_decl_tag_value(btf, fn_t, i, "arg:");
if (IS_ERR(tag) && PTR_ERR(tag) == -ENOENT) {
@ -7048,43 +7051,61 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
bpf_log(log, "arg#%d type tag is not supported in static functions\n", i);
return -EOPNOTSUPP;
}
if (strcmp(tag, "ctx") == 0) {
sub->args[i].arg_type = ARG_PTR_TO_CTX;
continue;
tags |= ARG_TAG_CTX;
} else if (strcmp(tag, "nonnull") == 0) {
tags |= ARG_TAG_NONNULL;
} else {
bpf_log(log, "arg#%d has unsupported set of tags\n", i);
return -EOPNOTSUPP;
}
if (strcmp(tag, "nonnull") == 0)
is_nonnull = true;
}
t = btf_type_by_id(btf, args[i].type);
while (btf_type_is_modifier(t))
t = btf_type_by_id(btf, t->type);
if (btf_type_is_ptr(t) && btf_get_prog_ctx_type(log, btf, t, prog_type, i)) {
if (!btf_type_is_ptr(t))
goto skip_pointer;
if ((tags & ARG_TAG_CTX) || btf_get_prog_ctx_type(log, btf, t, prog_type, i)) {
if (tags & ~ARG_TAG_CTX) {
bpf_log(log, "arg#%d has invalid combination of tags\n", i);
return -EINVAL;
}
sub->args[i].arg_type = ARG_PTR_TO_CTX;
continue;
}
if (btf_type_is_ptr(t) && btf_is_dynptr_ptr(btf, t)) {
if (btf_is_dynptr_ptr(btf, t)) {
if (tags) {
bpf_log(log, "arg#%d has invalid combination of tags\n", i);
return -EINVAL;
}
sub->args[i].arg_type = ARG_PTR_TO_DYNPTR | MEM_RDONLY;
continue;
}
if (is_global && btf_type_is_ptr(t)) {
if (is_global) { /* generic user data pointer */
u32 mem_size;
t = btf_type_skip_modifiers(btf, t->type, NULL);
ref_t = btf_resolve_size(btf, t, &mem_size);
if (IS_ERR(ref_t)) {
bpf_log(log,
"arg#%d reference type('%s %s') size cannot be determined: %ld\n",
i, btf_type_str(t), btf_name_by_offset(btf, t->name_off),
bpf_log(log, "arg#%d reference type('%s %s') size cannot be determined: %ld\n",
i, btf_type_str(t), btf_name_by_offset(btf, t->name_off),
PTR_ERR(ref_t));
return -EINVAL;
}
sub->args[i].arg_type = is_nonnull ? ARG_PTR_TO_MEM : ARG_PTR_TO_MEM_OR_NULL;
sub->args[i].arg_type = ARG_PTR_TO_MEM | PTR_MAYBE_NULL;
if (tags & ARG_TAG_NONNULL)
sub->args[i].arg_type &= ~PTR_MAYBE_NULL;
sub->args[i].mem_size = mem_size;
continue;
}
if (is_nonnull) {
bpf_log(log, "arg#%d marked as non-null, but is not a pointer type\n", i);
skip_pointer:
if (tags) {
bpf_log(log, "arg#%d has pointer tag, but is not a pointer type\n", i);
return -EINVAL;
}
if (btf_type_is_int(t) || btf_is_any_enum(t)) {

1
kernel/bpf/verifier.c
View file

@ -20058,7 +20058,6 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog)
state->first_insn_idx = env->subprog_info[subprog].start;
state->last_insn_idx = -1;
regs = state->frame[state->curframe]->regs;
if (subprog || env->prog->type == BPF_PROG_TYPE_EXT) {
const char *sub_name = subprog_name(env, subprog);