bpf: Add mptcp [gs]etsockopt per subflow

Closes: multipath-tcp#76
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>

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

@@ -329,6 +329,69 @@ static void test_mptcpify(void)
 	close(cgroup_fd);
 }
 
+static int getsetsockopt(void)
+{
+	int server_fd, client_fd, err = 0;
+
+	server_fd = start_mptcp_server(AF_INET, NULL, 0, 0);
+	if (!ASSERT_GE(server_fd, 0, "start_mptcp_server")) {
+		err = -EIO;
+		goto out;
+	}
+
+	client_fd = connect_to_fd(server_fd, 0);
+	if (!ASSERT_GE(client_fd, 0, "connect to fd")) {
+		err = -EIO;
+		goto close_server;
+	}
+
+	send_byte(client_fd);
+
+	close(client_fd);
+close_server:
+	close(server_fd);
+out:
+	return err;
+}
+
+static void run_test_sockopt(int cgroup_fd)
+{
+	struct mptcp_sock *skel;
+
+	skel = mptcp_sock__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel_load"))
+		goto cleanup;
+
+	skel->bss->page_size = getpagesize();
+
+	skel->links._setsockopt =
+		bpf_program__attach_cgroup(skel->progs._setsockopt, cgroup_fd);
+	if (!ASSERT_OK_PTR(skel->links._setsockopt, "setsockopt_link"))
+		goto cleanup;
+
+	skel->links._getsockopt =
+		bpf_program__attach_cgroup(skel->progs._getsockopt, cgroup_fd);
+	if (!ASSERT_OK_PTR(skel->links._getsockopt, "getsockopt_link"))
+		goto cleanup;
+
+	ASSERT_OK(getsetsockopt(), "getsetsockopt");
+
+cleanup:
+	mptcp_sock__destroy(skel);
+}
+
+void test_sockopt_mptcp(void)
+{
+	int cgroup_fd;
+
+	cgroup_fd = test__join_cgroup("/sockopt_mptcp");
+	if (!ASSERT_GE(cgroup_fd, 0, "join_cgroup /sockopt_mptcp"))
+		return;
+
+	run_test_sockopt(cgroup_fd);
+	close(cgroup_fd);
+}
+
 static const unsigned int total_bytes = 10 * 1024 * 1024;
 static int stop, duration;
 
@@ -693,6 +756,8 @@ void test_mptcp(void)
 		test_base();
 	if (test__start_subtest("mptcpify"))
 		test_mptcpify();
+	if (test__start_subtest("sockopt"))
+		test_sockopt_mptcp();
 	if (test__start_subtest("default"))
 		test_default();
 	if (test__start_subtest("first"))

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

@@ -9,6 +9,8 @@
 char _license[] SEC("license") = "GPL";
 __u32 token = 0;
 
+int page_size = 0; /* userspace should set it */
+
 struct mptcp_storage {
 	__u32 invoked;
 	__u32 is_mptcp;
@@ -86,3 +88,15 @@ int BPF_PROG(trace_mptcp_pm_new_connection, struct mptcp_sock *msk,
 
 	return 0;
 }
+
+SEC("cgroup/getsockopt")
+int _getsockopt(struct bpf_sockopt *ctx)
+{
+	return 1;
+}
+
+SEC("cgroup/setsockopt")
+int _setsockopt(struct bpf_sockopt *ctx)
+{
+	return 1;
+}