Test that socket-kept netns can be reopened via file handle.
Verify that a network namespace kept alive by a socket FD can be
reopened using file handles even after the creating process exits.
Signed-off-by: Christian Brauner <brauner@kernel.org>
---
.../testing/selftests/namespaces/siocgskns_test.c | 195 +++++++++++++++++++++
1 file changed, 195 insertions(+)
diff --git a/tools/testing/selftests/namespaces/siocgskns_test.c b/tools/testing/selftests/namespaces/siocgskns_test.c
index 98f6a0e1b9dd..a909232dba36 100644
--- a/tools/testing/selftests/namespaces/siocgskns_test.c
+++ b/tools/testing/selftests/namespaces/siocgskns_test.c
@@ -779,4 +779,199 @@ TEST(siocgskns_listns_visibility)
TH_LOG("Netns %llu correctly disappeared from listns() after socket closed", netns_id);
}
+/*
+ * Test that socket-kept netns can be reopened via file handle.
+ * Verify that a network namespace kept alive by a socket FD can be
+ * reopened using file handles even after the creating process exits.
+ */
+TEST(siocgskns_file_handle)
+{
+ int sock_fd, netns_fd, reopened_fd;
+ int ipc_sockets[2];
+ pid_t pid;
+ int status;
+ struct stat st1, st2;
+ ino_t netns_ino;
+ __u64 netns_id;
+ struct file_handle *handle;
+ struct nsfs_file_handle *nsfs_fh;
+ int ret;
+
+ /* Allocate file_handle structure for nsfs */
+ handle = malloc(sizeof(struct file_handle) + sizeof(struct nsfs_file_handle));
+ ASSERT_NE(handle, NULL);
+ handle->handle_bytes = sizeof(struct nsfs_file_handle);
+ handle->handle_type = FILEID_NSFS;
+
+ 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) {
+ free(handle);
+ close(sock_fd);
+ if (errno == ENOTTY || errno == EINVAL)
+ SKIP(return, "SIOCGSKNS not supported");
+ ASSERT_GE(netns_fd, 0);
+ }
+
+ ASSERT_EQ(fstat(netns_fd, &st1), 0);
+ netns_ino = st1.st_ino;
+
+ /* Get namespace ID */
+ ret = ioctl(netns_fd, NS_GET_ID, &netns_id);
+ if (ret < 0) {
+ free(handle);
+ close(sock_fd);
+ close(netns_fd);
+ if (errno == ENOTTY || errno == EINVAL)
+ SKIP(return, "NS_GET_ID not supported");
+ ASSERT_EQ(ret, 0);
+ }
+
+ /* Construct file handle from namespace ID */
+ nsfs_fh = (struct nsfs_file_handle *)handle->f_handle;
+ nsfs_fh->ns_id = netns_id;
+ nsfs_fh->ns_type = 0; /* Type field not needed for reopening */
+ nsfs_fh->ns_inum = 0; /* Inum field not needed for reopening */
+
+ TH_LOG("Constructed file handle for netns %lu (id=%llu)", netns_ino, netns_id);
+
+ /* Reopen namespace using file handle (while socket still keeps it alive) */
+ reopened_fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);
+ if (reopened_fd < 0) {
+ free(handle);
+ close(sock_fd);
+ if (errno == EOPNOTSUPP || errno == ENOSYS || errno == EBADF)
+ SKIP(return, "open_by_handle_at with FD_NSFS_ROOT not supported");
+ TH_LOG("open_by_handle_at failed: %s", strerror(errno));
+ ASSERT_GE(reopened_fd, 0);
+ }
+
+ /* Verify it's the same namespace */
+ ASSERT_EQ(fstat(reopened_fd, &st2), 0);
+ ASSERT_EQ(st1.st_ino, st2.st_ino);
+ ASSERT_EQ(st1.st_dev, st2.st_dev);
+
+ TH_LOG("Successfully reopened netns %lu via file handle", netns_ino);
+
+ close(reopened_fd);
+
+ /* Close the netns FD */
+ close(netns_fd);
+
+ /* Try to reopen via file handle - should fail since namespace is now inactive */
+ reopened_fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);
+ ASSERT_LT(reopened_fd, 0);
+ TH_LOG("Correctly failed to reopen inactive netns: %s", strerror(errno));
+
+ /* Get network namespace from socket */
+ netns_fd = ioctl(sock_fd, SIOCGSKNS);
+ if (netns_fd < 0) {
+ free(handle);
+ close(sock_fd);
+ if (errno == ENOTTY || errno == EINVAL)
+ SKIP(return, "SIOCGSKNS not supported");
+ ASSERT_GE(netns_fd, 0);
+ }
+
+ /* Reopen namespace using file handle (while socket still keeps it alive) */
+ reopened_fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);
+ if (reopened_fd < 0) {
+ free(handle);
+ close(sock_fd);
+ if (errno == EOPNOTSUPP || errno == ENOSYS || errno == EBADF)
+ SKIP(return, "open_by_handle_at with FD_NSFS_ROOT not supported");
+ TH_LOG("open_by_handle_at failed: %s", strerror(errno));
+ ASSERT_GE(reopened_fd, 0);
+ }
+
+ /* Verify it's the same namespace */
+ ASSERT_EQ(fstat(reopened_fd, &st2), 0);
+ ASSERT_EQ(st1.st_ino, st2.st_ino);
+ ASSERT_EQ(st1.st_dev, st2.st_dev);
+
+ TH_LOG("Successfully reopened netns %lu via file handle", netns_ino);
+
+ /* Close socket - namespace should become inactive */
+ close(sock_fd);
+ free(handle);
+}
+
TEST_HARNESS_MAIN
--
2.47.3