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 --- .../testing/selftests/namespaces/siocgskns_test.c | 203 +++++++++++++++++++++ 1 file changed, 203 insertions(+) diff --git a/tools/testing/selftests/namespaces/siocgskns_test.c b/tools/testing/selftests/namespaces/siocgskns_test.c index 7b3133f3898c..0ea5241f2b6f 100644 --- a/tools/testing/selftests/namespaces/siocgskns_test.c +++ b/tools/testing/selftests/namespaces/siocgskns_test.c @@ -781,4 +781,207 @@ 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)); + if (WEXITSTATUS(status) != 0) { + free(handle); + SKIP(close(sock_fd); return, "Child failed to create namespace"); + } + + /* 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); + if (reopened_fd >= 0) { + /* This might succeed if there's still a reference somewhere */ + TH_LOG("Warning: reopened netns after socket closed (fd=%d)", reopened_fd); + close(reopened_fd); + } else { + 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