Subject: [PATCH bpf-next v7 07/11] libbpf: implement bpf_prog_query_opts

From: Stanislav Fomichev <[email-masked]>
Date: Wed, 18 May 2022 15:55:27 -0700

Implement bpf_prog_query_opts as a more expendable version of
bpf_prog_query. Expose new prog_attach_flags and attach_btf_func_id as
well:

* prog_attach_flags is a per-program attach_type; relevant only for
  lsm cgroup program which might have different attach_flags
  per attach_btf_id
* attach_btf_func_id is a new field expose for prog_query which
  specifies real btf function id for lsm cgroup attachments

Signed-off-by: Stanislav Fomichev <[email-masked]>
---
 tools/include/uapi/linux/bpf.h |  5 ++++
 tools/lib/bpf/bpf.c            | 42 +++++++++++++++++++++++++++-------
 tools/lib/bpf/bpf.h            | 15 ++++++++++++
 tools/lib/bpf/libbpf.map       |  1 +
 4 files changed, 55 insertions(+), 8 deletions(-)

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index b9d2d6de63a7..432fc5f49567 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1432,6 +1432,7 @@ union bpf_attr {
 		__u32		attach_flags;
 		__aligned_u64	prog_ids;
 		__u32		prog_cnt;
+		__aligned_u64	prog_attach_flags; /* output: per-program attach_flags */
 	} query;
 
 	struct { /* anonymous struct used by BPF_RAW_TRACEPOINT_OPEN command */
@@ -5911,6 +5912,10 @@ struct bpf_prog_info {
 	__u64 run_cnt;
 	__u64 recursion_misses;
 	__u32 verified_insns;
+	/* BTF ID of the function to attach to within BTF object identified
+	 * by btf_id.
+	 */
+	__u32 attach_btf_func_id;
 } __attribute__((aligned(8)));
 
 struct bpf_map_info {
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 4677644d80f4..f0c2c2ea5a93 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -968,28 +968,54 @@ int bpf_iter_create(int link_fd)
 	return libbpf_err_errno(fd);
 }
 
-int bpf_prog_query(int target_fd, enum bpf_attach_type type, __u32 query_flags,
-		   __u32 *attach_flags, __u32 *prog_ids, __u32 *prog_cnt)
+int bpf_prog_query_opts(int target_fd,
+			enum bpf_attach_type type,
+			struct bpf_prog_query_opts *opts)
 {
 	union bpf_attr attr;
 	int ret;
 
 	memset(&attr, 0, sizeof(attr));
+
+	if (!OPTS_VALID(opts, bpf_prog_query_opts))
+		return libbpf_err(-EINVAL);
+
 	attr.query.target_fd	= target_fd;
 	attr.query.attach_type	= type;
-	attr.query.query_flags	= query_flags;
-	attr.query.prog_cnt	= *prog_cnt;
-	attr.query.prog_ids	= ptr_to_u64(prog_ids);
+	attr.query.query_flags	= OPTS_GET(opts, query_flags, 0);
+	attr.query.prog_cnt	= OPTS_GET(opts, prog_cnt, 0);
+	attr.query.prog_ids	= ptr_to_u64(OPTS_GET(opts, prog_ids, NULL));
+	attr.query.prog_attach_flags = ptr_to_u64(OPTS_GET(opts, prog_attach_flags, NULL));
 
 	ret = sys_bpf(BPF_PROG_QUERY, &attr, sizeof(attr));
 
-	if (attach_flags)
-		*attach_flags = attr.query.attach_flags;
-	*prog_cnt = attr.query.prog_cnt;
+	if (OPTS_HAS(opts, prog_cnt))
+		opts->prog_cnt = attr.query.prog_cnt;
+	if (OPTS_HAS(opts, attach_flags))
+		opts->attach_flags = attr.query.attach_flags;
 
 	return libbpf_err_errno(ret);
 }
 
+int bpf_prog_query(int target_fd, enum bpf_attach_type type, __u32 query_flags,
+		   __u32 *attach_flags, __u32 *prog_ids, __u32 *prog_cnt)
+{
+	LIBBPF_OPTS(bpf_prog_query_opts, p);
+	int ret;
+
+	p.query_flags = query_flags;
+	p.prog_ids = prog_ids;
+	p.prog_cnt = *prog_cnt;
+
+	ret = bpf_prog_query_opts(target_fd, type, &p);
+
+	if (attach_flags)
+		*attach_flags = p.attach_flags;
+	*prog_cnt = p.prog_cnt;
+
+	return ret;
+}
+
 int bpf_prog_test_run(int prog_fd, int repeat, void *data, __u32 size,
 		      void *data_out, __u32 *size_out, __u32 *retval,
 		      __u32 *duration)
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 2e0d3731e4c0..11ffbed99637 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -484,9 +484,24 @@ LIBBPF_API int bpf_map_get_fd_by_id(__u32 id);
 LIBBPF_API int bpf_btf_get_fd_by_id(__u32 id);
 LIBBPF_API int bpf_link_get_fd_by_id(__u32 id);
 LIBBPF_API int bpf_obj_get_info_by_fd(int bpf_fd, void *info, __u32 *info_len);
+
+struct bpf_prog_query_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+	__u32 query_flags;
+	__u32 attach_flags; /* output argument */
+	__u32 *prog_ids;
+	__u32 prog_cnt; /* input+output argument */
+	__u32 *prog_attach_flags;
+};
+#define bpf_prog_query_opts__last_field prog_attach_flags
+
+LIBBPF_API int bpf_prog_query_opts(int target_fd,
+				   enum bpf_attach_type type,
+				   struct bpf_prog_query_opts *opts);
 LIBBPF_API int bpf_prog_query(int target_fd, enum bpf_attach_type type,
 			      __u32 query_flags, __u32 *attach_flags,
 			      __u32 *prog_ids, __u32 *prog_cnt);
+
 LIBBPF_API int bpf_raw_tracepoint_open(const char *name, int prog_fd);
 LIBBPF_API int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf,
 				 __u32 *buf_len, __u32 *prog_id, __u32 *fd_type,
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 6b36f46ab5d8..24f7a5147bf2 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -452,6 +452,7 @@ LIBBPF_0.8.0 {
 		bpf_map_delete_elem_flags;
 		bpf_object__destroy_subskeleton;
 		bpf_object__open_subskeleton;
+		bpf_prog_query_opts;
 		bpf_program__attach_kprobe_multi_opts;
 		bpf_program__attach_trace_opts;
 		bpf_program__attach_usdt;
-- 
2.36.1.124.g0e6072fb45-goog