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authorLorenz Bauer <lmb@cloudflare.com>2020-09-21 15:12:20 +0300
committerAlexei Starovoitov <ast@kernel.org>2020-09-22 01:00:40 +0300
commit9436ef6e862b9ca22e5b12f87b106e07d5af4cae (patch)
treed492819683666eba4815ed5d705e7a9cf281c3fa /include
parent27774b7073b5d520c80f1fcb8e9993fc139f21bd (diff)
downloadlinux-9436ef6e862b9ca22e5b12f87b106e07d5af4cae.tar.xz
bpf: Allow specifying a BTF ID per argument in function protos
Function prototypes using ARG_PTR_TO_BTF_ID currently use two ways to signal which BTF IDs are acceptable. First, bpf_func_proto.btf_id is an array of IDs, one for each argument. This array is only accessed up to the highest numbered argument that uses ARG_PTR_TO_BTF_ID and may therefore be less than five arguments long. It usually points at a BTF_ID_LIST. Second, check_btf_id is a function pointer that is called by the verifier if present. It gets the actual BTF ID of the register, and the argument number we're currently checking. It turns out that the only user check_arg_btf_id ignores the argument, and is simply used to check whether the BTF ID has a struct sock_common at it's start. Replace both of these mechanisms with an explicit BTF ID for each argument in a function proto. Thanks to btf_struct_ids_match this is very flexible: check_arg_btf_id can be replaced by requiring struct sock_common. Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20200921121227.255763-5-lmb@cloudflare.com
Diffstat (limited to 'include')
-rw-r--r--include/linux/bpf.h18
1 files changed, 10 insertions, 8 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 0478b20d335b..87b0d5dcc1ff 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -326,12 +326,16 @@ struct bpf_func_proto {
};
enum bpf_arg_type arg_type[5];
};
- int *btf_id; /* BTF ids of arguments */
- bool (*check_btf_id)(u32 btf_id, u32 arg); /* if the argument btf_id is
- * valid. Often used if more
- * than one btf id is permitted
- * for this argument.
- */
+ union {
+ struct {
+ u32 *arg1_btf_id;
+ u32 *arg2_btf_id;
+ u32 *arg3_btf_id;
+ u32 *arg4_btf_id;
+ u32 *arg5_btf_id;
+ };
+ u32 *arg_btf_id[5];
+ };
int *ret_btf_id; /* return value btf_id */
bool (*allowed)(const struct bpf_prog *prog);
};
@@ -1385,8 +1389,6 @@ int btf_struct_access(struct bpf_verifier_log *log,
u32 *next_btf_id);
bool btf_struct_ids_match(struct bpf_verifier_log *log,
int off, u32 id, u32 need_type_id);
-int btf_resolve_helper_id(struct bpf_verifier_log *log,
- const struct bpf_func_proto *fn, int);
int btf_distill_func_proto(struct bpf_verifier_log *log,
struct btf *btf,