selftests/namespaces: sixth inactive namespace resurrection test

Test multiple sockets keep the same network namespace active. Create
multiple sockets, verify closing some doesn't affect others.

Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-60-2e6f823ebdc0@kernel.org
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/tools/testing/selftests/namespaces/siocgskns_test.c b/tools/testing/selftests/namespaces/siocgskns_test.c
index bbfef3c51ac1f870739f62a8549bfc8e93e5df90..231830daf5dc7420564afb31fde4bea9f2cca7d6 100644 (file)
--- a/tools/testing/selftests/namespaces/siocgskns_test.c
+++ b/tools/testing/selftests/namespaces/siocgskns_test.c
@@ -333,4 +333,72 @@ TEST(siocgskns_non_socket)
        close(pipefd[1]);
 }
 
+/*
+ * Test multiple sockets keep the same network namespace active.
+ * Create multiple sockets, verify closing some doesn't affect others.
+ */
+TEST(siocgskns_multiple_sockets)
+{
+       int socks[5];
+       int netns_fds[5];
+       int i;
+       struct stat st;
+       ino_t netns_ino;
+
+       /* Create new network namespace */
+       ASSERT_EQ(unshare(CLONE_NEWNET), 0);
+
+       /* Create multiple sockets */
+       for (i = 0; i < 5; i++) {
+               socks[i] = socket(AF_INET, SOCK_STREAM, 0);
+               ASSERT_GE(socks[i], 0);
+       }
+
+       /* Get netns from all sockets */
+       for (i = 0; i < 5; i++) {
+               netns_fds[i] = ioctl(socks[i], SIOCGSKNS);
+               if (netns_fds[i] < 0) {
+                       int j;
+                       for (j = 0; j <= i; j++) {
+                               close(socks[j]);
+                               if (j < i && netns_fds[j] >= 0)
+                                       close(netns_fds[j]);
+                       }
+                       if (errno == ENOTTY || errno == EINVAL)
+                               SKIP(return, "SIOCGSKNS not supported");
+                       ASSERT_GE(netns_fds[i], 0);
+               }
+       }
+
+       /* Verify all point to same netns */
+       ASSERT_EQ(fstat(netns_fds[0], &st), 0);
+       netns_ino = st.st_ino;
+
+       for (i = 1; i < 5; i++) {
+               ASSERT_EQ(fstat(netns_fds[i], &st), 0);
+               ASSERT_EQ(st.st_ino, netns_ino);
+       }
+
+       /* Close some sockets */
+       for (i = 0; i < 3; i++) {
+               close(socks[i]);
+       }
+
+       /* Remaining netns FDs should still be valid */
+       for (i = 3; i < 5; i++) {
+               char path[64];
+               snprintf(path, sizeof(path), "/proc/self/fd/%d", netns_fds[i]);
+               int test_fd = open(path, O_RDONLY);
+               ASSERT_GE(test_fd, 0);
+               close(test_fd);
+       }
+
+       /* Cleanup */
+       for (i = 0; i < 5; i++) {
+               if (i >= 3)
+                       close(socks[i]);
+               close(netns_fds[i]);
+       }
+}
+
 TEST_HARNESS_MAIN