selftests/bpf: Add a test case for udp sockmap

Add a test case to ensure redirection between two UDP 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/20210331023237.41094-16-xiyou.wangcong@gmail.com

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

@@ -1603,6 +1603,141 @@ static void test_reuseport(struct test_sockmap_listen *skel,
 	}
 }
 
+static void udp_redir_to_connected(int family, int sotype, int sock_mapfd,
+				   int verd_mapfd, enum redir_mode mode)
+{
+	const char *log_prefix = redir_mode_str(mode);
+	struct sockaddr_storage addr;
+	int c0, c1, p0, p1;
+	unsigned int pass;
+	socklen_t len;
+	int err, n;
+	u64 value;
+	u32 key;
+	char b;
+
+	zero_verdict_count(verd_mapfd);
+
+	p0 = socket_loopback(family, sotype | SOCK_NONBLOCK);
+	if (p0 < 0)
+		return;
+	len = sizeof(addr);
+	err = xgetsockname(p0, sockaddr(&addr), &len);
+	if (err)
+		goto close_peer0;
+
+	c0 = xsocket(family, sotype | SOCK_NONBLOCK, 0);
+	if (c0 < 0)
+		goto close_peer0;
+	err = xconnect(c0, sockaddr(&addr), len);
+	if (err)
+		goto close_cli0;
+	err = xgetsockname(c0, sockaddr(&addr), &len);
+	if (err)
+		goto close_cli0;
+	err = xconnect(p0, sockaddr(&addr), len);
+	if (err)
+		goto close_cli0;
+
+	p1 = socket_loopback(family, sotype | SOCK_NONBLOCK);
+	if (p1 < 0)
+		goto close_cli0;
+	err = xgetsockname(p1, sockaddr(&addr), &len);
+	if (err)
+		goto close_cli0;
+
+	c1 = xsocket(family, sotype | SOCK_NONBLOCK, 0);
+	if (c1 < 0)
+		goto close_peer1;
+	err = xconnect(c1, sockaddr(&addr), len);
+	if (err)
+		goto close_cli1;
+	err = xgetsockname(c1, sockaddr(&addr), &len);
+	if (err)
+		goto close_cli1;
+	err = xconnect(p1, sockaddr(&addr), len);
+	if (err)
+		goto close_cli1;
+
+	key = 0;
+	value = p0;
+	err = xbpf_map_update_elem(sock_mapfd, &key, &value, BPF_NOEXIST);
+	if (err)
+		goto close_cli1;
+
+	key = 1;
+	value = p1;
+	err = xbpf_map_update_elem(sock_mapfd, &key, &value, BPF_NOEXIST);
+	if (err)
+		goto close_cli1;
+
+	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_cli1;
+
+	key = SK_PASS;
+	err = xbpf_map_lookup_elem(verd_mapfd, &key, &pass);
+	if (err)
+		goto close_cli1;
+	if (pass != 1)
+		FAIL("%s: want pass count 1, have %d", log_prefix, pass);
+
+	n = read(mode == REDIR_INGRESS ? p0 : c0, &b, 1);
+	if (n < 0)
+		FAIL_ERRNO("%s: read", log_prefix);
+	if (n == 0)
+		FAIL("%s: incomplete read", log_prefix);
+
+close_cli1:
+	xclose(c1);
+close_peer1:
+	xclose(p1);
+close_cli0:
+	xclose(c0);
+close_peer0:
+	xclose(p0);
+}
+
+static void udp_skb_redir_to_connected(struct test_sockmap_listen *skel,
+				       struct bpf_map *inner_map, int family)
+{
+	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;
+	udp_redir_to_connected(family, SOCK_DGRAM, sock_map, verdict_map,
+			       REDIR_EGRESS);
+	skel->bss->test_ingress = true;
+	udp_redir_to_connected(family, SOCK_DGRAM, sock_map, verdict_map,
+			       REDIR_INGRESS);
+
+	xbpf_prog_detach2(verdict, sock_map, BPF_SK_SKB_VERDICT);
+}
+
+static void test_udp_redir(struct test_sockmap_listen *skel, struct bpf_map *map,
+			   int family)
+{
+	const char *family_name, *map_name;
+	char s[MAX_TEST_NAME];
+
+	family_name = family_str(family);
+	map_name = map_type_str(map);
+	snprintf(s, sizeof(s), "%s %s %s", map_name, family_name, __func__);
+	if (!test__start_subtest(s))
+		return;
+	udp_skb_redir_to_connected(skel, map, family);
+}
+
 static void run_tests(struct test_sockmap_listen *skel, struct bpf_map *map,
 		      int family)
 {
@@ -1611,6 +1746,7 @@ static void run_tests(struct test_sockmap_listen *skel, struct bpf_map *map,
 	test_redir(skel, map, family, SOCK_STREAM);
 	test_reuseport(skel, map, family, SOCK_STREAM);
 	test_reuseport(skel, map, family, SOCK_DGRAM);
+	test_udp_redir(skel, map, family);
 }
 
 void test_sockmap_listen(void)

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

@@ -29,6 +29,7 @@ struct {
 } verdict_map SEC(".maps");
 
 static volatile bool test_sockmap; /* toggled by user-space */
+static volatile bool test_ingress; /* toggled by user-space */
 
 SEC("sk_skb/stream_parser")
 int prog_stream_parser(struct __sk_buff *skb)
@@ -55,6 +56,27 @@ int prog_stream_verdict(struct __sk_buff *skb)
 	return verdict;
 }
 
+SEC("sk_skb/skb_verdict")
+int prog_skb_verdict(struct __sk_buff *skb)
+{
+	unsigned int *count;
+	__u32 zero = 0;
+	int verdict;
+
+	if (test_sockmap)
+		verdict = bpf_sk_redirect_map(skb, &sock_map, zero,
+					      test_ingress ? BPF_F_INGRESS : 0);
+	else
+		verdict = bpf_sk_redirect_hash(skb, &sock_hash, &zero,
+					       test_ingress ? BPF_F_INGRESS : 0);
+
+	count = bpf_map_lookup_elem(&verdict_map, &verdict);
+	if (count)
+		(*count)++;
+
+	return verdict;
+}
+
 SEC("sk_msg")
 int prog_msg_verdict(struct sk_msg_md *msg)
 {