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authorAndrii Nakryiko <andrii@kernel.org>2024-01-30 01:06:46 +0100
committerAlexei Starovoitov <ast@kernel.org>2024-01-30 18:41:50 +0100
commit8f2b44cd9d69ec36c9ce9623993978babb575ee8 (patch)
tree45c7502fc70ead45db93a3891838d7f2c364d6ac /kernel/bpf
parentbpf: add __arg_trusted global func arg tag (diff)
downloadlinux-8f2b44cd9d69ec36c9ce9623993978babb575ee8.tar.xz
linux-8f2b44cd9d69ec36c9ce9623993978babb575ee8.zip
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/bpf')
-rw-r--r--kernel/bpf/btf.c10
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)) {