+int bus_machine_method_bind_mount(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
+ _cleanup_close_pair_ int errno_pipe_fd[2] = { -1, -1 };
+ char mount_slave[] = "/tmp/propagate.XXXXXX", *mount_tmp, *mount_outside, *p;
+ bool mount_slave_created = false, mount_slave_mounted = false,
+ mount_tmp_created = false, mount_tmp_mounted = false,
+ mount_outside_created = false, mount_outside_mounted = false;
+ const char *dest, *src;
+ Machine *m = userdata;
+ int read_only, make_directory;
+ pid_t child;
+ siginfo_t si;
+ int r;
+
+ if (m->class != MACHINE_CONTAINER)
+ return sd_bus_error_setf(error, SD_BUS_ERROR_NOT_SUPPORTED, "Bind mounting is only supported on container machines.");
+
+ r = sd_bus_message_read(message, "ssbb", &src, &dest, &read_only, &make_directory);
+ if (r < 0)
+ return r;
+
+ if (!path_is_absolute(src) || !path_is_safe(src))
+ return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Source path must be absolute and not contain ../.");
+
+ if (isempty(dest))
+ dest = src;
+ else if (!path_is_absolute(dest) || !path_is_safe(dest))
+ return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Source path must be absolute and not contain ../.");
+
+ /* One day, when bind mounting /proc/self/fd/n works across
+ * namespace boundaries we should rework this logic to make
+ * use of it... */
+
+ p = strjoina("/run/systemd/nspawn/propagate/", m->name, "/");
+ if (laccess(p, F_OK) < 0)
+ return sd_bus_error_setf(error, SD_BUS_ERROR_NOT_SUPPORTED, "Container does not allow propagation of mount points.");
+
+ /* 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 sd_bus_error_set_errnof(error, errno, "Failed to create playground %s: %m", mount_slave);
+
+ mount_slave_created = true;
+
+ if (mount(mount_slave, mount_slave, NULL, MS_BIND, NULL) < 0) {
+ r = sd_bus_error_set_errnof(error, errno, "Failed to make bind mount %s: %m", mount_slave);
+ goto finish;
+ }
+
+ mount_slave_mounted = true;
+
+ if (mount(NULL, mount_slave, NULL, MS_SLAVE, NULL) < 0) {
+ r = sd_bus_error_set_errnof(error, errno, "Failed to remount slave %s: %m", mount_slave);
+ goto finish;
+ }
+
+ /* Second, we mount the source directory to a directory inside
+ of our MS_SLAVE playground. */
+ mount_tmp = strjoina(mount_slave, "/mount");
+ if (mkdir(mount_tmp, 0700) < 0) {
+ r = sd_bus_error_set_errnof(error, errno, "Failed to create temporary mount point %s: %m", mount_tmp);
+ goto finish;
+ }
+
+ mount_tmp_created = true;
+
+ if (mount(src, mount_tmp, NULL, MS_BIND, NULL) < 0) {
+ r = sd_bus_error_set_errnof(error, errno, "Failed to overmount %s: %m", mount_tmp);
+ goto finish;
+ }
+
+ mount_tmp_mounted = true;
+
+ /* Third, we remount the new bind mount read-only if requested. */
+ if (read_only)
+ if (mount(NULL, mount_tmp, NULL, MS_BIND|MS_REMOUNT|MS_RDONLY, NULL) < 0) {
+ r = sd_bus_error_set_errnof(error, errno, "Failed to remount read-only %s: %m", mount_tmp);
+ 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 = strjoina("/run/systemd/nspawn/propagate/", m->name, "/XXXXXX");
+ if (!mkdtemp(mount_outside)) {
+ r = sd_bus_error_set_errnof(error, errno, "Cannot create propagation directory %s: %m", mount_outside);
+ goto finish;
+ }
+
+ mount_outside_created = true;
+
+ if (mount(mount_tmp, mount_outside, NULL, MS_MOVE, NULL) < 0) {
+ r = sd_bus_error_set_errnof(error, errno, "Failed to move %s to %s: %m", mount_tmp, mount_outside);
+ 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;
+
+ if (pipe2(errno_pipe_fd, O_CLOEXEC|O_NONBLOCK) < 0) {
+ r = sd_bus_error_set_errnof(error, errno, "Failed to create pipe: %m");
+ goto finish;
+ }
+
+ child = fork();
+ if (child < 0) {
+ r = sd_bus_error_set_errnof(error, errno, "Failed to fork(): %m");
+ goto finish;
+ }
+
+ if (child == 0) {
+ const char *mount_inside;
+ int mntfd;
+ const char *q;
+
+ errno_pipe_fd[0] = safe_close(errno_pipe_fd[0]);
+
+ q = procfs_file_alloca(m->leader, "ns/mnt");
+ mntfd = open(q, O_RDONLY|O_NOCTTY|O_CLOEXEC);
+ if (mntfd < 0) {
+ r = log_error_errno(errno, "Failed to open mount namespace of leader: %m");
+ goto child_fail;
+ }
+
+ if (setns(mntfd, CLONE_NEWNS) < 0) {
+ r = log_error_errno(errno, "Failed to join namespace of leader: %m");
+ goto child_fail;
+ }
+
+ if (make_directory)
+ (void) mkdir_p(dest, 0755);
+
+ /* Fifth, move the mount to the right place inside */
+ mount_inside = strjoina("/run/systemd/nspawn/incoming/", basename(mount_outside));
+ if (mount(mount_inside, dest, NULL, MS_MOVE, NULL) < 0) {
+ r = log_error_errno(errno, "Failed to mount: %m");
+ goto child_fail;
+ }
+
+ _exit(EXIT_SUCCESS);
+
+ child_fail:
+ (void) write(errno_pipe_fd[1], &r, sizeof(r));
+ errno_pipe_fd[1] = safe_close(errno_pipe_fd[1]);
+
+ _exit(EXIT_FAILURE);
+ }
+
+ errno_pipe_fd[1] = safe_close(errno_pipe_fd[1]);
+
+ r = wait_for_terminate(child, &si);
+ if (r < 0) {
+ r = sd_bus_error_set_errnof(error, errno, "Failed to wait for client: %m");
+ goto finish;
+ }
+ if (si.si_code != CLD_EXITED) {
+ r = sd_bus_error_setf(error, SD_BUS_ERROR_FAILED, "Client died abnormally.");
+ goto finish;
+ }
+ if (si.si_status != EXIT_SUCCESS) {
+
+ if (read(errno_pipe_fd[0], &r, sizeof(r)) == sizeof(r))
+ r = sd_bus_error_set_errnof(error, r, "Failed to mount in container: %m");
+ else
+ r = sd_bus_error_setf(error, SD_BUS_ERROR_FAILED, "Client failed.");
+ goto finish;
+ }
+
+ r = sd_bus_reply_method_return(message, NULL);
+
+finish:
+ if (mount_outside_mounted)
+ umount(mount_outside);
+ if (mount_outside_created)
+ rmdir(mount_outside);
+
+ if (mount_tmp_mounted)
+ umount(mount_tmp);
+ if (mount_tmp_created)
+ rmdir(mount_tmp);
+
+ if (mount_slave_mounted)
+ umount(mount_slave);
+ if (mount_slave_created)
+ rmdir(mount_slave);
+
+ return r;
+}
+
~ianmdlvl / elogind.git / commitdiff