diff options
| author | Andrii Nakryiko <andrii@kernel.org> | 2024-01-29 16:06:46 -0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2024-01-30 09:41:50 -0800 |
| commit | 8f2b44cd9d69ec36c9ce9623993978babb575ee8 (patch) | |
| tree | 45c7502fc70ead45db93a3891838d7f2c364d6ac /kernel | |
| parent | e2b3c4ff5d183da6d1863c2321413406a2752e7a (diff) | |
bpf: add arg:nullable tag to be combined with trusted pointers
Add ability to mark arg:trusted arguments with optional arg:nullable
tag to mark it as PTR_TO_BTF_ID_OR_NULL variant, which will allow
callers to pass NULL, and subsequently will force global subprog's code
to do NULL check. This allows to have "optional" PTR_TO_BTF_ID values
passed into global subprogs.
For now arg:nullable cannot be combined with anything else.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240130000648.2144827-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/btf.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index ed7a05815984..c8c6e6cf18e7 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -7056,6 +7056,7 @@ enum btf_arg_tag { ARG_TAG_CTX = 0x1, ARG_TAG_NONNULL = 0x2, ARG_TAG_TRUSTED = 0x4, + ARG_TAG_NULLABLE = 0x8, }; /* Process BTF of a function to produce high-level expectation of function @@ -7161,6 +7162,8 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) tags |= ARG_TAG_TRUSTED; } else if (strcmp(tag, "nonnull") == 0) { tags |= ARG_TAG_NONNULL; + } else if (strcmp(tag, "nullable") == 0) { + tags |= ARG_TAG_NULLABLE; } else { bpf_log(log, "arg#%d has unsupported set of tags\n", i); return -EOPNOTSUPP; @@ -7210,12 +7213,19 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) return kern_type_id; sub->args[i].arg_type = ARG_PTR_TO_BTF_ID | PTR_TRUSTED; + if (tags & ARG_TAG_NULLABLE) + sub->args[i].arg_type |= PTR_MAYBE_NULL; sub->args[i].btf_id = kern_type_id; continue; } if (is_global) { /* generic user data pointer */ u32 mem_size; + if (tags & ARG_TAG_NULLABLE) { + bpf_log(log, "arg#%d has invalid combination of tags\n", i); + return -EINVAL; + } + t = btf_type_skip_modifiers(btf, t->type, NULL); ref_t = btf_resolve_size(btf, t, &mem_size); if (IS_ERR(ref_t)) { |