selftests/namespaces: ninth inactive namespace resurrection test

Test that socket-kept netns appears in listns() output.
Verify that a network namespace kept alive by a socket FD appears in
listns() output even after the creating process exits, and that it
disappears when the socket is closed.

Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-63-2e6f823ebdc0@kernel.org
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 47c1524a864825abc71f1ec80ddd7719c03a89b0..98f6a0e1b9dd16d22a570fbc769e10ac4da9d5b7 100644 (file)
--- a/tools/testing/selftests/namespaces/siocgskns_test.c
+++ b/tools/testing/selftests/namespaces/siocgskns_test.c
@@ -576,4 +576,207 @@ TEST(siocgskns_ipv6)
        close(current_netns_fd);
 }
 
+/*
+ * Test that socket-kept netns appears in listns() output.
+ * Verify that a network namespace kept alive by a socket FD appears in
+ * listns() output even after the creating process exits, and that it
+ * disappears when the socket is closed.
+ */
+TEST(siocgskns_listns_visibility)
+{
+       int sock_fd, netns_fd, owner_fd;
+       int ipc_sockets[2];
+       pid_t pid;
+       int status;
+       __u64 netns_id, owner_id;
+       struct ns_id_req req = {
+               .size = sizeof(req),
+               .spare = 0,
+               .ns_id = 0,
+               .ns_type = CLONE_NEWNET,
+               .spare2 = 0,
+               .user_ns_id = 0,
+       };
+       __u64 ns_ids[256];
+       int ret, i;
+       bool found_netns = false;
+
+       EXPECT_EQ(socketpair(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets), 0);
+
+       pid = fork();
+       ASSERT_GE(pid, 0);
+
+       if (pid == 0) {
+               /* Child: create new netns and socket */
+               close(ipc_sockets[0]);
+
+               if (unshare(CLONE_NEWNET) < 0) {
+                       close(ipc_sockets[1]);
+                       exit(1);
+               }
+
+               sock_fd = socket(AF_INET, SOCK_DGRAM, 0);
+               if (sock_fd < 0) {
+                       close(ipc_sockets[1]);
+                       exit(1);
+               }
+
+               /* Send socket FD to parent via SCM_RIGHTS */
+               struct msghdr msg = {0};
+               struct iovec iov = {0};
+               char buf[1] = {'X'};
+               char cmsg_buf[CMSG_SPACE(sizeof(int))];
+
+               iov.iov_base = buf;
+               iov.iov_len = 1;
+               msg.msg_iov = &iov;
+               msg.msg_iovlen = 1;
+               msg.msg_control = cmsg_buf;
+               msg.msg_controllen = sizeof(cmsg_buf);
+
+               struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
+               cmsg->cmsg_level = SOL_SOCKET;
+               cmsg->cmsg_type = SCM_RIGHTS;
+               cmsg->cmsg_len = CMSG_LEN(sizeof(int));
+               memcpy(CMSG_DATA(cmsg), &sock_fd, sizeof(int));
+
+               if (sendmsg(ipc_sockets[1], &msg, 0) < 0) {
+                       close(sock_fd);
+                       close(ipc_sockets[1]);
+                       exit(1);
+               }
+
+               close(sock_fd);
+               close(ipc_sockets[1]);
+               exit(0);
+       }
+
+       /* Parent: receive socket FD */
+       close(ipc_sockets[1]);
+
+       struct msghdr msg = {0};
+       struct iovec iov = {0};
+       char buf[1];
+       char cmsg_buf[CMSG_SPACE(sizeof(int))];
+
+       iov.iov_base = buf;
+       iov.iov_len = 1;
+       msg.msg_iov = &iov;
+       msg.msg_iovlen = 1;
+       msg.msg_control = cmsg_buf;
+       msg.msg_controllen = sizeof(cmsg_buf);
+
+       ssize_t n = recvmsg(ipc_sockets[0], &msg, 0);
+       close(ipc_sockets[0]);
+       ASSERT_EQ(n, 1);
+
+       struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
+       ASSERT_NE(cmsg, NULL);
+       memcpy(&sock_fd, CMSG_DATA(cmsg), sizeof(int));
+
+       /* Wait for child to exit */
+       waitpid(pid, &status, 0);
+       ASSERT_TRUE(WIFEXITED(status));
+       ASSERT_EQ(WEXITSTATUS(status), 0);
+
+       /* Get network namespace from socket */
+       netns_fd = ioctl(sock_fd, SIOCGSKNS);
+       if (netns_fd < 0) {
+               close(sock_fd);
+               if (errno == ENOTTY || errno == EINVAL)
+                       SKIP(return, "SIOCGSKNS not supported");
+               ASSERT_GE(netns_fd, 0);
+       }
+
+       /* Get namespace ID */
+       ret = ioctl(netns_fd, NS_GET_ID, &netns_id);
+       if (ret < 0) {
+               close(sock_fd);
+               close(netns_fd);
+               if (errno == ENOTTY || errno == EINVAL)
+                       SKIP(return, "NS_GET_ID not supported");
+               ASSERT_EQ(ret, 0);
+       }
+
+       /* Get owner user namespace */
+       owner_fd = ioctl(netns_fd, NS_GET_USERNS);
+       if (owner_fd < 0) {
+               close(sock_fd);
+               close(netns_fd);
+               if (errno == ENOTTY || errno == EINVAL)
+                       SKIP(return, "NS_GET_USERNS not supported");
+               ASSERT_GE(owner_fd, 0);
+       }
+
+       /* Get owner namespace ID */
+       ret = ioctl(owner_fd, NS_GET_ID, &owner_id);
+       if (ret < 0) {
+               close(owner_fd);
+               close(sock_fd);
+               close(netns_fd);
+               ASSERT_EQ(ret, 0);
+       }
+       close(owner_fd);
+
+       /* Namespace should appear in listns() output */
+       ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0);
+       if (ret < 0) {
+               close(sock_fd);
+               close(netns_fd);
+               if (errno == ENOSYS)
+                       SKIP(return, "listns() not supported");
+               TH_LOG("listns failed: %s", strerror(errno));
+               ASSERT_GE(ret, 0);
+       }
+
+       /* Search for our network namespace in the list */
+       for (i = 0; i < ret; i++) {
+               if (ns_ids[i] == netns_id) {
+                       found_netns = true;
+                       break;
+               }
+       }
+
+       ASSERT_TRUE(found_netns);
+       TH_LOG("Found netns %llu in listns() output (kept alive by socket)", netns_id);
+
+       /* Now verify with owner filtering */
+       req.user_ns_id = owner_id;
+       found_netns = false;
+
+       ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0);
+       ASSERT_GE(ret, 0);
+
+       for (i = 0; i < ret; i++) {
+               if (ns_ids[i] == netns_id) {
+                       found_netns = true;
+                       break;
+               }
+       }
+
+       ASSERT_TRUE(found_netns);
+       TH_LOG("Found netns %llu owned by userns %llu", netns_id, owner_id);
+
+       /* Close socket - namespace should become inactive and disappear from listns() */
+       close(sock_fd);
+       close(netns_fd);
+
+       /* Verify it's no longer in listns() output */
+       req.user_ns_id = 0;
+       found_netns = false;
+
+       ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0);
+       ASSERT_GE(ret, 0);
+
+       for (i = 0; i < ret; i++) {
+               if (ns_ids[i] == netns_id) {
+                       found_netns = true;
+                       break;
+               }
+       }
+
+       ASSERT_FALSE(found_netns);
+       TH_LOG("Netns %llu correctly disappeared from listns() after socket closed", netns_id);
+}
+
 TEST_HARNESS_MAIN