selftests/bpf: Monitor traffic for tc_redirect.

Enable traffic monitoring for the test case tc_redirect.
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240815053254.470944-5-thinker.li@gmail.comSigned-off-by: Martin KaFai Lau <martin.lau@kernel.org>

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

@@ -68,6 +68,7 @@
 		__FILE__, __LINE__, strerror(errno), ##__VA_ARGS__)
 
 static const char * const namespaces[] = {NS_SRC, NS_FWD, NS_DST, NULL};
+static struct netns_obj *netns_objs[3];
 
 static int write_file(const char *path, const char *newval)
 {
@@ -87,27 +88,41 @@ static int write_file(const char *path, const char *newval)
 
 static int netns_setup_namespaces(const char *verb)
 {
+	struct netns_obj **ns_obj = netns_objs;
 	const char * const *ns = namespaces;
-	char cmd[128];
 
 	while (*ns) {
-		snprintf(cmd, sizeof(cmd), "ip netns %s %s", verb, *ns);
-		if (!ASSERT_OK(system(cmd), cmd))
-			return -1;
+		if (strcmp(verb, "add") == 0) {
+			*ns_obj = netns_new(*ns, false);
+			if (!ASSERT_OK_PTR(*ns_obj, "netns_new"))
+				return -1;
+		} else {
+			if (!ASSERT_OK_PTR(*ns_obj, "netns_obj is NULL"))
+				return -1;
+			netns_free(*ns_obj);
+			*ns_obj = NULL;
+		}
 		ns++;
+		ns_obj++;
 	}
 	return 0;
 }
 
 static void netns_setup_namespaces_nofail(const char *verb)
 {
+	struct netns_obj **ns_obj = netns_objs;
 	const char * const *ns = namespaces;
-	char cmd[128];
 
 	while (*ns) {
-		snprintf(cmd, sizeof(cmd), "ip netns %s %s > /dev/null 2>&1", verb, *ns);
-		system(cmd);
+		if (strcmp(verb, "add") == 0) {
+			*ns_obj = netns_new(*ns, false);
+		} else {
+			if (*ns_obj)
+				netns_free(*ns_obj);
+			*ns_obj = NULL;
+		}
 		ns++;
+		ns_obj++;
 	}
 }