bpf: Add struct_ops context information to struct bpf_prog_aux

This patch adds struct_ops context information to struct bpf_prog_aux.

This context information will be used in the kfunc filter.

Currently the added context information includes struct_ops member
offset and a pointer to struct bpf_struct_ops.

Signed-off-by: Juntong Deng <juntong.deng@outlook.com>
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20250319215358.2287371-2-ameryhung@gmail.com

Author: juntongdeng

include/linux/bpf.h

@@ -1521,6 +1521,7 @@ struct bpf_prog_aux {
 	u32 real_func_cnt; /* includes hidden progs, only used for JIT and freeing progs */
 	u32 func_idx; /* 0 for non-func prog, the index in func array for func prog */
 	u32 attach_btf_id; /* in-kernel BTF type id to attach to */
+	u32 attach_st_ops_member_off;
 	u32 ctx_arg_info_size;
 	u32 max_rdonly_access;
 	u32 max_rdwr_access;
@@ -1566,6 +1567,7 @@ struct bpf_prog_aux {
 #endif
 	struct bpf_ksym ksym;
 	const struct bpf_prog_ops *ops;
+	const struct bpf_struct_ops *st_ops;
 	struct bpf_map **used_maps;
 	struct mutex used_maps_mutex; /* mutex for used_maps and used_map_cnt */
 	struct btf_mod_pair *used_btfs;

kernel/bpf/verifier.c

@@ -22736,7 +22736,7 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env)
 	const struct btf_member *member;
 	struct bpf_prog *prog = env->prog;
 	bool has_refcounted_arg = false;
-	u32 btf_id, member_idx;
+	u32 btf_id, member_idx, member_off;
 	struct btf *btf;
 	const char *mname;
 	int i, err;
@@ -22787,7 +22787,8 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env)
 		return -EINVAL;
 	}
 
-	err = bpf_struct_ops_supported(st_ops, __btf_member_bit_offset(t, member) / 8);
+	member_off = __btf_member_bit_offset(t, member) / 8;
+	err = bpf_struct_ops_supported(st_ops, member_off);
 	if (err) {
 		verbose(env, "attach to unsupported member %s of struct %s\n",
 			mname, st_ops->name);
@@ -22826,6 +22827,9 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env)
 		}
 	}
 
+	prog->aux->st_ops = st_ops;
+	prog->aux->attach_st_ops_member_off = member_off;
+
 	prog->aux->attach_func_proto = func_proto;
 	prog->aux->attach_func_name = mname;
 	env->ops = st_ops->verifier_ops;