selftests/bpf: Add a test case for unix sockmap

Add a test case to ensure redirection between two AF_UNIX
datagram sockets work.

Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210704190252.11866-11-xiyou.wangcong@gmail.com

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

@@ -1435,6 +1435,8 @@ static const char *family_str(sa_family_t family)
 		return "IPv4";
 	case AF_INET6:
 		return "IPv6";
+	case AF_UNIX:
+		return "Unix";
 	default:
 		return "unknown";
 	}
@@ -1557,6 +1559,99 @@ static void test_redir(struct test_sockmap_listen *skel, struct bpf_map *map,
 	}
 }
 
+static void unix_redir_to_connected(int sotype, int sock_mapfd,
+			       int verd_mapfd, enum redir_mode mode)
+{
+	const char *log_prefix = redir_mode_str(mode);
+	int c0, c1, p0, p1;
+	unsigned int pass;
+	int retries = 100;
+	int err, n;
+	int sfd[2];
+	u32 key;
+	char b;
+
+	zero_verdict_count(verd_mapfd);
+
+	if (socketpair(AF_UNIX, sotype | SOCK_NONBLOCK, 0, sfd))
+		return;
+	c0 = sfd[0], p0 = sfd[1];
+
+	if (socketpair(AF_UNIX, sotype | SOCK_NONBLOCK, 0, sfd))
+		goto close0;
+	c1 = sfd[0], p1 = sfd[1];
+
+	err = add_to_sockmap(sock_mapfd, p0, p1);
+	if (err)
+		goto close;
+
+	n = write(c1, "a", 1);
+	if (n < 0)
+		FAIL_ERRNO("%s: write", log_prefix);
+	if (n == 0)
+		FAIL("%s: incomplete write", log_prefix);
+	if (n < 1)
+		goto close;
+
+	key = SK_PASS;
+	err = xbpf_map_lookup_elem(verd_mapfd, &key, &pass);
+	if (err)
+		goto close;
+	if (pass != 1)
+		FAIL("%s: want pass count 1, have %d", log_prefix, pass);
+
+again:
+	n = read(mode == REDIR_INGRESS ? p0 : c0, &b, 1);
+	if (n < 0) {
+		if (errno == EAGAIN && retries--)
+			goto again;
+		FAIL_ERRNO("%s: read", log_prefix);
+	}
+	if (n == 0)
+		FAIL("%s: incomplete read", log_prefix);
+
+close:
+	xclose(c1);
+	xclose(p1);
+close0:
+	xclose(c0);
+	xclose(p0);
+}
+
+static void unix_skb_redir_to_connected(struct test_sockmap_listen *skel,
+					struct bpf_map *inner_map, int sotype)
+{
+	int verdict = bpf_program__fd(skel->progs.prog_skb_verdict);
+	int verdict_map = bpf_map__fd(skel->maps.verdict_map);
+	int sock_map = bpf_map__fd(inner_map);
+	int err;
+
+	err = xbpf_prog_attach(verdict, sock_map, BPF_SK_SKB_VERDICT, 0);
+	if (err)
+		return;
+
+	skel->bss->test_ingress = false;
+	unix_redir_to_connected(sotype, sock_map, verdict_map, REDIR_EGRESS);
+	skel->bss->test_ingress = true;
+	unix_redir_to_connected(sotype, sock_map, verdict_map, REDIR_INGRESS);
+
+	xbpf_prog_detach2(verdict, sock_map, BPF_SK_SKB_VERDICT);
+}
+
+static void test_unix_redir(struct test_sockmap_listen *skel, struct bpf_map *map,
+			    int sotype)
+{
+	const char *family_name, *map_name;
+	char s[MAX_TEST_NAME];
+
+	family_name = family_str(AF_UNIX);
+	map_name = map_type_str(map);
+	snprintf(s, sizeof(s), "%s %s %s", map_name, family_name, __func__);
+	if (!test__start_subtest(s))
+		return;
+	unix_skb_redir_to_connected(skel, map, sotype);
+}
+
 static void test_reuseport(struct test_sockmap_listen *skel,
 			   struct bpf_map *map, int family, int sotype)
 {
@@ -1754,10 +1849,12 @@ void test_sockmap_listen(void)
 	skel->bss->test_sockmap = true;
 	run_tests(skel, skel->maps.sock_map, AF_INET);
 	run_tests(skel, skel->maps.sock_map, AF_INET6);
+	test_unix_redir(skel, skel->maps.sock_map, SOCK_DGRAM);
 
 	skel->bss->test_sockmap = false;
 	run_tests(skel, skel->maps.sock_hash, AF_INET);
 	run_tests(skel, skel->maps.sock_hash, AF_INET6);
+	test_unix_redir(skel, skel->maps.sock_hash, SOCK_DGRAM);
 
 	test_sockmap_listen__destroy(skel);
 }