- /* One day, when bind mounting /proc/self/fd/n works across
- * namespace boundaries we should rework this logic to make
- * use of it... */
-
- dest = argv[3] ?: argv[2];
- if (!path_is_absolute(dest)) {
- log_error("Destination path not absolute.");
- return -EINVAL;
- }
-
- p = strappenda("/run/systemd/nspawn/propagate/", argv[1], "/");
- if (access(p, F_OK) < 0) {
- log_error("Container does not allow propagation of mount points.");
- return -ENOTSUP;
- }
-
- r = machine_get_leader(bus, argv[1], &leader);
- if (r < 0)
- return r;
-
- /* Our goal is to install a new bind mount into the container,
- possibly read-only. This is irritatingly complex
- unfortunately, currently.
-
- First, we start by creating a private playground in /tmp,
- that we can mount MS_SLAVE. (Which is necessary, since
- MS_MOUNT cannot be applied to mounts with MS_SHARED parent
- mounts.) */
-
- if (!mkdtemp(mount_slave))
- return log_error_errno(errno, "Failed to create playground: %m");
-
- mount_slave_created = true;
-
- if (mount(mount_slave, mount_slave, NULL, MS_BIND, NULL) < 0) {
- r = log_error_errno(errno, "Failed to make bind mount: %m");
- goto finish;
- }
-
- mount_slave_mounted = true;
-
- if (mount(NULL, mount_slave, NULL, MS_SLAVE, NULL) < 0) {
- r = log_error_errno(errno, "Failed to remount slave: %m");
- goto finish;
- }
-
- /* Second, we mount the source directory to a directory inside
- of our MS_SLAVE playground. */
- mount_tmp = strappenda(mount_slave, "/mount");
- if (mkdir(mount_tmp, 0700) < 0) {
- r = log_error_errno(errno, "Failed to create temporary mount: %m");
- goto finish;
- }
-
- mount_tmp_created = true;
-
- if (mount(argv[2], mount_tmp, NULL, MS_BIND, NULL) < 0) {
- r = log_error_errno(errno, "Failed to overmount: %m");
- goto finish;
- }
-
- mount_tmp_mounted = true;
-
- /* Third, we remount the new bind mount read-only if requested. */
- if (arg_read_only)
- if (mount(NULL, mount_tmp, NULL, MS_BIND|MS_REMOUNT|MS_RDONLY, NULL) < 0) {
- r = log_error_errno(errno, "Failed to mark read-only: %m");
- goto finish;
- }
-
- /* Fourth, we move the new bind mount into the propagation
- * directory. This way it will appear there read-only
- * right-away. */
-
- mount_outside = strappenda("/run/systemd/nspawn/propagate/", argv[1], "/XXXXXX");
- if (!mkdtemp(mount_outside)) {
- r = log_error_errno(errno, "Cannot create propagation directory: %m");
- goto finish;
- }
-
- mount_outside_created = true;
-
- if (mount(mount_tmp, mount_outside, NULL, MS_MOVE, NULL) < 0) {
- r = log_error_errno(errno, "Failed to move: %m");
- goto finish;
- }
-
- mount_outside_mounted = true;
- mount_tmp_mounted = false;
-
- (void) rmdir(mount_tmp);
- mount_tmp_created = false;
-
- (void) umount(mount_slave);
- mount_slave_mounted = false;
-
- (void) rmdir(mount_slave);
- mount_slave_created = false;
-
- child = fork();
- if (child < 0) {
- r = log_error_errno(errno, "Failed to fork(): %m");
- goto finish;
- }
-
- if (child == 0) {
- const char *mount_inside;
- int mntfd;
- const char *q;
-
- q = procfs_file_alloca(leader, "ns/mnt");
- mntfd = open(q, O_RDONLY|O_NOCTTY|O_CLOEXEC);
- if (mntfd < 0) {
- log_error_errno(errno, "Failed to open mount namespace of leader: %m");
- _exit(EXIT_FAILURE);
- }
-
- if (setns(mntfd, CLONE_NEWNS) < 0) {
- log_error_errno(errno, "Failed to join namespace of leader: %m");
- _exit(EXIT_FAILURE);
- }
-
- if (arg_mkdir)
- mkdir_p(dest, 0755);
-
- /* Fifth, move the mount to the right place inside */
- mount_inside = strappenda("/run/systemd/nspawn/incoming/", basename(mount_outside));
- if (mount(mount_inside, dest, NULL, MS_MOVE, NULL) < 0) {
- log_error_errno(errno, "Failed to mount: %m");
- _exit(EXIT_FAILURE);
- }
-
- _exit(EXIT_SUCCESS);
- }