selftests/bpf: Add mptcpify selftest

This patch extends the MPTCP test base, add a selftest test_mptcpify()
for the mptcpify case.

Open and load the mptcpify test prog to mptcpify the TCP sockets
dynamically, then use start_server() and connect_to_fd() to create a
TCP socket, but actually what's created is an MPTCP socket, which can
be verified through the stored local BSS variable.

Signed-off-by: Geliang Tang <[email protected]>

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

@@ -6,13 +6,17 @@
 #include "cgroup_helpers.h"
 #include "network_helpers.h"
 #include "mptcp_sock.skel.h"
+#include "mptcpify.skel.h"
 #include "mptcp_bpf_first.skel.h"
 #include "mptcp_bpf_bkup.skel.h"
 #include "mptcp_bpf_rr.skel.h"
 #include "mptcp_bpf_red.skel.h"
 
 char NS_TEST[32];
 
+#ifndef IPPROTO_MPTCP
+#define IPPROTO_MPTCP 262
+#endif
 #ifndef TCP_CA_NAME_MAX
 #define TCP_CA_NAME_MAX	16
 #endif
@@ -200,6 +204,87 @@ static void test_base(void)
 	close(cgroup_fd);
 }
 
+static void send_byte(int fd)
+{
+	char b = 0x55;
+
+	ASSERT_EQ(write(fd, &b, sizeof(b)), 1, "send single byte");
+}
+
+static int verify_mptcpify(int protocol)
+{
+	char cmd[128];
+	int err = 0;
+
+	if (!ASSERT_EQ(protocol, IPPROTO_MPTCP, "unexpected protocol"))
+		err++;
+
+	snprintf(cmd, sizeof(cmd),
+		 "ip netns exec %s ss -tOni | grep -q tcp-ulp-mptcp",
+		 NS_TEST);
+	ASSERT_OK(system(cmd), "No tcp-ulp-mptcp found!");
+
+	return err;
+}
+
+static int run_mptcpify(int cgroup_fd)
+{
+	int server_fd, client_fd, err = 0;
+	struct mptcpify *mptcpify_skel;
+
+	mptcpify_skel = mptcpify__open_and_load();
+	if (!ASSERT_OK_PTR(mptcpify_skel, "skel_open_load"))
+		return -EIO;
+
+	mptcpify_skel->links.sock =
+		bpf_program__attach_cgroup(mptcpify_skel->progs.sock, cgroup_fd);
+	if (!ASSERT_OK_PTR(mptcpify_skel->links.sock, "cg_attach_sock"))
+		goto out;
+
+	/* without MPTCP */
+	server_fd = start_server(AF_INET, SOCK_STREAM, NULL, 0, 0);
+	if (!ASSERT_GE(server_fd, 0, "start_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);
+	err += verify_mptcpify(mptcpify_skel->bss->protocol);
+
+	close(client_fd);
+close_server:
+	close(server_fd);
+out:
+	mptcpify__destroy(mptcpify_skel);
+	return err;
+}
+
+static void test_mptcpify(void)
+{
+	struct nstoken *nstoken = NULL;
+	int cgroup_fd;
+
+	cgroup_fd = test__join_cgroup("/mptcpify");
+	if (!ASSERT_GE(cgroup_fd, 0, "test__join_cgroup"))
+		return;
+
+	nstoken = create_netns();
+	if (!ASSERT_OK_PTR(nstoken, "create_netns"))
+		goto fail;
+
+	ASSERT_OK(run_mptcpify(cgroup_fd), "run_mptcpify");
+
+fail:
+	cleanup_netns(nstoken);
+	close(cgroup_fd);
+}
+
 static const unsigned int total_bytes = 10 * 1024 * 1024;
 static int stop, duration;
 
@@ -459,6 +544,8 @@ void test_mptcp(void)
 {
 	if (test__start_subtest("base"))
 		test_base();
+	if (test__start_subtest("mptcpify"))
+		test_mptcpify();
 	if (test__start_subtest("first"))
 		test_first();
 	if (test__start_subtest("bkup"))