selftests: bpf: test BPF_PROG_QUERY for progs attached to sockmap

Add test for querying progs attached to sockmap. we use an existing
libbpf query interface to query prog cnt before and after progs
attaching to sockmap and check whether the queried prog id is right.

Signed-off-by: Di Zhu <zhudi2@huawei.com>
Acked-by: Yonghong Song <yhs@fb.com>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/r/20220119014005.1209-2-zhudi2@huawei.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Author: Di Zhu

tools/testing/selftests/bpf/prog_tests/sockmap_basic.c

@@ -8,6 +8,7 @@
 #include "test_sockmap_update.skel.h"
 #include "test_sockmap_invalid_update.skel.h"
 #include "test_sockmap_skb_verdict_attach.skel.h"
+#include "test_sockmap_progs_query.skel.h"
 #include "bpf_iter_sockmap.skel.h"
 
 #define TCP_REPAIR		19	/* TCP sock is under repair right now */
@@ -315,6 +316,63 @@ static void test_sockmap_skb_verdict_attach(enum bpf_attach_type first,
 	test_sockmap_skb_verdict_attach__destroy(skel);
 }
 
+static __u32 query_prog_id(int prog_fd)
+{
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
+	int err;
+
+	err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (!ASSERT_OK(err, "bpf_obj_get_info_by_fd") ||
+	    !ASSERT_EQ(info_len, sizeof(info), "bpf_obj_get_info_by_fd"))
+		return 0;
+
+	return info.id;
+}
+
+static void test_sockmap_progs_query(enum bpf_attach_type attach_type)
+{
+	struct test_sockmap_progs_query *skel;
+	int err, map_fd, verdict_fd;
+	__u32 attach_flags = 0;
+	__u32 prog_ids[3] = {};
+	__u32 prog_cnt = 3;
+
+	skel = test_sockmap_progs_query__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "test_sockmap_progs_query__open_and_load"))
+		return;
+
+	map_fd = bpf_map__fd(skel->maps.sock_map);
+
+	if (attach_type == BPF_SK_MSG_VERDICT)
+		verdict_fd = bpf_program__fd(skel->progs.prog_skmsg_verdict);
+	else
+		verdict_fd = bpf_program__fd(skel->progs.prog_skb_verdict);
+
+	err = bpf_prog_query(map_fd, attach_type, 0 /* query flags */,
+			     &attach_flags, prog_ids, &prog_cnt);
+	ASSERT_OK(err, "bpf_prog_query failed");
+	ASSERT_EQ(attach_flags,  0, "wrong attach_flags on query");
+	ASSERT_EQ(prog_cnt, 0, "wrong program count on query");
+
+	err = bpf_prog_attach(verdict_fd, map_fd, attach_type, 0);
+	if (!ASSERT_OK(err, "bpf_prog_attach failed"))
+		goto out;
+
+	prog_cnt = 1;
+	err = bpf_prog_query(map_fd, attach_type, 0 /* query flags */,
+			     &attach_flags, prog_ids, &prog_cnt);
+	ASSERT_OK(err, "bpf_prog_query failed");
+	ASSERT_EQ(attach_flags, 0, "wrong attach_flags on query");
+	ASSERT_EQ(prog_cnt, 1, "wrong program count on query");
+	ASSERT_EQ(prog_ids[0], query_prog_id(verdict_fd),
+		  "wrong prog_ids on query");
+
+	bpf_prog_detach2(verdict_fd, map_fd, attach_type);
+out:
+	test_sockmap_progs_query__destroy(skel);
+}
+
 void test_sockmap_basic(void)
 {
 	if (test__start_subtest("sockmap create_update_free"))
@@ -341,4 +399,12 @@ void test_sockmap_basic(void)
 		test_sockmap_skb_verdict_attach(BPF_SK_SKB_STREAM_VERDICT,
 						BPF_SK_SKB_VERDICT);
 	}
+	if (test__start_subtest("sockmap msg_verdict progs query"))
+		test_sockmap_progs_query(BPF_SK_MSG_VERDICT);
+	if (test__start_subtest("sockmap stream_parser progs query"))
+		test_sockmap_progs_query(BPF_SK_SKB_STREAM_PARSER);
+	if (test__start_subtest("sockmap stream_verdict progs query"))
+		test_sockmap_progs_query(BPF_SK_SKB_STREAM_VERDICT);
+	if (test__start_subtest("sockmap skb_verdict progs query"))
+		test_sockmap_progs_query(BPF_SK_SKB_VERDICT);
 }

tools/testing/selftests/bpf/progs/test_sockmap_progs_query.c

@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+
+struct {
+	__uint(type, BPF_MAP_TYPE_SOCKMAP);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, __u64);
+} sock_map SEC(".maps");
+
+SEC("sk_skb")
+int prog_skb_verdict(struct __sk_buff *skb)
+{
+	return SK_PASS;
+}
+
+SEC("sk_msg")
+int prog_skmsg_verdict(struct sk_msg_md *msg)
+{
+	return SK_PASS;
+}
+
+char _license[] SEC("license") = "GPL";