[PATCH bpf-next] selftests/bpf: run mptcp in a dedicated netns

[Hangbin Liu <liuhangbin@gmail.com>]

The current mptcp test is run in init netns. If the user or default
system config disabled mptcp, the test will fail. Let's run the mptcp
test in a dedicated netns to avoid none kernel default mptcp setting.

Suggested-by: Martin KaFai Lau <martin.lau@linux.dev>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
 .../testing/selftests/bpf/prog_tests/mptcp.c  | 24 +++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/mptcp.c b/tools/testing/selftests/bpf/prog_tests/mptcp.c
index 59f08d6d1d53..8a4ed9510ec7 100644
--- a/tools/testing/selftests/bpf/prog_tests/mptcp.c
+++ b/tools/testing/selftests/bpf/prog_tests/mptcp.c
@@ -7,6 +7,16 @@
 #include "network_helpers.h"
 #include "mptcp_sock.skel.h"
 
+#define SYS(fmt, ...)						\
+	({							\
+		char cmd[1024];					\
+		snprintf(cmd, sizeof(cmd), fmt, ##__VA_ARGS__);	\
+		if (!ASSERT_OK(system(cmd), cmd))		\
+			goto cmd_fail;				\
+	})
+
+#define NS_TEST "mptcp_ns"
+
 #ifndef TCP_CA_NAME_MAX
 #define TCP_CA_NAME_MAX	16
 #endif
@@ -138,12 +148,20 @@ static int run_test(int cgroup_fd, int server_fd, bool is_mptcp)
 
 static void test_base(void)
 {
+	struct nstoken *nstoken = NULL;
 	int server_fd, cgroup_fd;
 
 	cgroup_fd = test__join_cgroup("/mptcp");
 	if (!ASSERT_GE(cgroup_fd, 0, "test__join_cgroup"))
 		return;
 
+	SYS("ip netns add %s", NS_TEST);
+	SYS("ip -net %s link set dev lo up", NS_TEST);
+
+	nstoken = open_netns(NS_TEST);
+	if (!ASSERT_OK_PTR(nstoken, "open_netns"))
+		goto cmd_fail;
+
 	/* without MPTCP */
 	server_fd = start_server(AF_INET, SOCK_STREAM, NULL, 0, 0);
 	if (!ASSERT_GE(server_fd, 0, "start_server"))
@@ -163,6 +181,12 @@ static void test_base(void)
 
 	close(server_fd);
 
+cmd_fail:
+	if (nstoken)
+		close_netns(nstoken);
+
+	system("ip netns del " NS_TEST " >& /dev/null");
+
 close_cgroup_fd:
 	close(cgroup_fd);
 }
-- 
2.38.1