/* SPDX-License-Identifier: LGPL-2.1+ */ /*** Copyright © 2010 ProFUSION embedded systems ***/ #include <errno.h> #include <fcntl.h> #include <linux/loop.h> #include <string.h> #include <sys/mount.h> #include <sys/swap.h> /* This needs to be after sys/mount.h :( */ #include <libmount.h> #include "sd-device.h" #include "alloc-util.h" #include "blockdev-util.h" #include "def.h" #include "device-util.h" #include "escape.h" #include "fd-util.h" #include "fstab-util.h" #include "linux-3.13/dm-ioctl.h" #include "mount-setup.h" #include "mount-util.h" #include "path-util.h" #include "process-util.h" #include "signal-util.h" #include "string-util.h" #include "umount.h" #include "util.h" #include "virt.h" DEFINE_TRIVIAL_CLEANUP_FUNC(struct libmnt_table*, mnt_free_table); DEFINE_TRIVIAL_CLEANUP_FUNC(struct libmnt_iter*, mnt_free_iter); static void mount_point_free(MountPoint **head, MountPoint *m) { assert(head); assert(m); LIST_REMOVE(mount_point, *head, m); free(m->path); free(m->remount_options); free(m); } void mount_points_list_free(MountPoint **head) { assert(head); while (*head) mount_point_free(head, *head); } int mount_points_list_get(const char *mountinfo, MountPoint **head) { _cleanup_(mnt_free_tablep) struct libmnt_table *t = NULL; _cleanup_(mnt_free_iterp) struct libmnt_iter *i = NULL; int r; assert(head); t = mnt_new_table(); i = mnt_new_iter(MNT_ITER_FORWARD); if (!t || !i) return log_oom(); r = mnt_table_parse_mtab(t, mountinfo); if (r < 0) return log_error_errno(r, "Failed to parse %s: %m", mountinfo); for (;;) { struct libmnt_fs *fs; const char *path, *fstype; _cleanup_free_ char *options = NULL; _cleanup_free_ char *p = NULL; unsigned long remount_flags = 0u; _cleanup_free_ char *remount_options = NULL; bool try_remount_ro; MountPoint *m; r = mnt_table_next_fs(t, i, &fs); if (r == 1) break; if (r < 0) return log_error_errno(r, "Failed to get next entry from %s: %m", mountinfo); path = mnt_fs_get_target(fs); if (!path) continue; if (cunescape(path, UNESCAPE_RELAX, &p) < 0) return log_oom(); fstype = mnt_fs_get_fstype(fs); /* Combine the generic VFS options with the FS-specific * options. Duplicates are not a problem here, because the only * options that should come up twice are typically ro/rw, which * are turned into MS_RDONLY or the invertion of it. * * Even if there are duplicates later in mount_option_mangle() * it shouldn't hurt anyways as they override each other. */ if (!strextend_with_separator(&options, ",", mnt_fs_get_vfs_options(fs), NULL)) return log_oom(); if (!strextend_with_separator(&options, ",", mnt_fs_get_fs_options(fs), NULL)) return log_oom(); /* Ignore mount points we can't unmount because they * are API or because we are keeping them open (like * /dev/console). Also, ignore all mounts below API * file systems, since they are likely virtual too, * and hence not worth spending time on. Also, in * unprivileged containers we might lack the rights to * unmount these things, hence don't bother. */ if (mount_point_is_api(p) || mount_point_ignore(p) || path_startswith(p, "/dev") || path_startswith(p, "/sys") || path_startswith(p, "/proc")) continue; /* If we are in a container, don't attempt to * read-only mount anything as that brings no real * benefits, but might confuse the host, as we remount * the superblock here, not the bind mount. * * If the filesystem is a network fs, also skip the * remount. It brings no value (we cannot leave * a "dirty fs") and could hang if the network is down. * Note that umount2() is more careful and will not * hang because of the network being down. */ try_remount_ro = detect_container() <= 0 && !fstype_is_network(fstype) && !fstype_is_api_vfs(fstype) && !fstype_is_ro(fstype) && !fstab_test_yes_no_option(options, "ro\0rw\0"); if (try_remount_ro) { /* mount(2) states that mount flags and options need to be exactly the same * as they were when the filesystem was mounted, except for the desired * changes. So we reconstruct both here and adjust them for the later * remount call too. */ r = mnt_fs_get_propagation(fs, &remount_flags); if (r < 0) { log_warning_errno(r, "mnt_fs_get_propagation() failed for %s, ignoring: %m", path); continue; } r = mount_option_mangle(options, remount_flags, &remount_flags, &remount_options); if (r < 0) { log_warning_errno(r, "mount_option_mangle failed for %s, ignoring: %m", path); continue; } /* MS_BIND is special. If it is provided it will only make the mount-point * read-only. If left out, the super block itself is remounted, which we want. */ remount_flags = (remount_flags|MS_REMOUNT|MS_RDONLY) & ~MS_BIND; } m = new0(MountPoint, 1); if (!m) return log_oom(); free_and_replace(m->path, p); free_and_replace(m->remount_options, remount_options); m->remount_flags = remount_flags; m->try_remount_ro = try_remount_ro; LIST_PREPEND(mount_point, *head, m); } return 0; } int swap_list_get(const char *swaps, MountPoint **head) { _cleanup_(mnt_free_tablep) struct libmnt_table *t = NULL; _cleanup_(mnt_free_iterp) struct libmnt_iter *i = NULL; int r; assert(head); t = mnt_new_table(); i = mnt_new_iter(MNT_ITER_FORWARD); if (!t || !i) return log_oom(); r = mnt_table_parse_swaps(t, swaps); if (r < 0) return log_error_errno(r, "Failed to parse %s: %m", swaps); for (;;) { struct libmnt_fs *fs; MountPoint *swap; const char *source; _cleanup_free_ char *d = NULL; r = mnt_table_next_fs(t, i, &fs); if (r == 1) break; if (r < 0) return log_error_errno(r, "Failed to get next entry from %s: %m", swaps); source = mnt_fs_get_source(fs); if (!source) continue; r = cunescape(source, UNESCAPE_RELAX, &d); if (r < 0) return r; swap = new0(MountPoint, 1); if (!swap) return -ENOMEM; free_and_replace(swap->path, d); LIST_PREPEND(mount_point, *head, swap); } return 0; } static int loopback_list_get(MountPoint **head) { _cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL; sd_device *d; int r; assert(head); r = sd_device_enumerator_new(&e); if (r < 0) return r; r = sd_device_enumerator_allow_uninitialized(e); if (r < 0) return r; r = sd_device_enumerator_add_match_subsystem(e, "block", true); if (r < 0) return r; r = sd_device_enumerator_add_match_sysname(e, "loop*"); if (r < 0) return r; r = sd_device_enumerator_add_match_sysattr(e, "loop/backing_file", NULL, true); if (r < 0) return r; FOREACH_DEVICE(e, d) { _cleanup_free_ char *p = NULL; const char *dn; MountPoint *lb; if (sd_device_get_devname(d, &dn) < 0) continue; p = strdup(dn); if (!p) return -ENOMEM; lb = new(MountPoint, 1); if (!lb) return -ENOMEM; *lb = (MountPoint) { .path = TAKE_PTR(p), }; LIST_PREPEND(mount_point, *head, lb); } return 0; } static int dm_list_get(MountPoint **head) { _cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL; sd_device *d; int r; assert(head); r = sd_device_enumerator_new(&e); if (r < 0) return r; r = sd_device_enumerator_allow_uninitialized(e); if (r < 0) return r; r = sd_device_enumerator_add_match_subsystem(e, "block", true); if (r < 0) return r; r = sd_device_enumerator_add_match_sysname(e, "dm-*"); if (r < 0) return r; FOREACH_DEVICE(e, d) { _cleanup_free_ char *p = NULL; const char *dn; MountPoint *m; dev_t devnum; if (sd_device_get_devnum(d, &devnum) < 0 || sd_device_get_devname(d, &dn) < 0) continue; p = strdup(dn); if (!p) return -ENOMEM; m = new(MountPoint, 1); if (!m) return -ENOMEM; *m = (MountPoint) { .path = TAKE_PTR(p), .devnum = devnum, }; LIST_PREPEND(mount_point, *head, m); } return 0; } static int delete_loopback(const char *device) { _cleanup_close_ int fd = -1; int r; assert(device); fd = open(device, O_RDONLY|O_CLOEXEC); if (fd < 0) return errno == ENOENT ? 0 : -errno; r = ioctl(fd, LOOP_CLR_FD, 0); if (r >= 0) return 1; /* ENXIO: not bound, so no error */ if (errno == ENXIO) return 0; return -errno; } static int delete_dm(dev_t devnum) { struct dm_ioctl dm = { .version = { DM_VERSION_MAJOR, DM_VERSION_MINOR, DM_VERSION_PATCHLEVEL }, .data_size = sizeof(dm), .dev = devnum, }; _cleanup_close_ int fd = -1; assert(major(devnum) != 0); fd = open("/dev/mapper/control", O_RDWR|O_CLOEXEC); if (fd < 0) return -errno; if (ioctl(fd, DM_DEV_REMOVE, &dm) < 0) return -errno; return 0; } static bool nonunmountable_path(const char *path) { return path_equal(path, "/") #if ! HAVE_SPLIT_USR || path_equal(path, "/usr") #endif || path_startswith(path, "/run/initramfs"); } static int remount_with_timeout(MountPoint *m, int umount_log_level) { pid_t pid; int r; BLOCK_SIGNALS(SIGCHLD); assert(m); /* Due to the possiblity of a remount operation hanging, we * fork a child process and set a timeout. If the timeout * lapses, the assumption is that that particular remount * failed. */ r = safe_fork("(sd-remount)", FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_LOG|FORK_REOPEN_LOG, &pid); if (r < 0) return r; if (r == 0) { log_info("Remounting '%s' read-only in with options '%s'.", m->path, m->remount_options); /* Start the mount operation here in the child */ r = mount(NULL, m->path, NULL, m->remount_flags, m->remount_options); if (r < 0) log_full_errno(umount_log_level, errno, "Failed to remount '%s' read-only: %m", m->path); _exit(r < 0 ? EXIT_FAILURE : EXIT_SUCCESS); } r = wait_for_terminate_with_timeout(pid, DEFAULT_TIMEOUT_USEC); if (r == -ETIMEDOUT) { log_error_errno(r, "Remounting '%s' timed out, issuing SIGKILL to PID " PID_FMT ".", m->path, pid); (void) kill(pid, SIGKILL); } else if (r == -EPROTO) log_debug_errno(r, "Remounting '%s' failed abnormally, child process " PID_FMT " aborted or exited non-zero.", m->path, pid); else if (r < 0) log_error_errno(r, "Remounting '%s' failed unexpectedly, couldn't wait for child process " PID_FMT ": %m", m->path, pid); return r; } static int umount_with_timeout(MountPoint *m, int umount_log_level) { pid_t pid; int r; BLOCK_SIGNALS(SIGCHLD); assert(m); /* Due to the possiblity of a umount operation hanging, we * fork a child process and set a timeout. If the timeout * lapses, the assumption is that that particular umount * failed. */ r = safe_fork("(sd-umount)", FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_LOG|FORK_REOPEN_LOG, &pid); if (r < 0) return r; if (r == 0) { log_info("Unmounting '%s'.", m->path); /* Start the mount operation here in the child Using MNT_FORCE * causes some filesystems (e.g. FUSE and NFS and other network * filesystems) to abort any pending requests and return -EIO * rather than blocking indefinitely. If the filesysten is * "busy", this may allow processes to die, thus making the * filesystem less busy so the unmount might succeed (rather * then return EBUSY).*/ r = umount2(m->path, MNT_FORCE); if (r < 0) log_full_errno(umount_log_level, errno, "Failed to unmount %s: %m", m->path); _exit(r < 0 ? EXIT_FAILURE : EXIT_SUCCESS); } r = wait_for_terminate_with_timeout(pid, DEFAULT_TIMEOUT_USEC); if (r == -ETIMEDOUT) { log_error_errno(r, "Unmounting '%s' timed out, issuing SIGKILL to PID " PID_FMT ".", m->path, pid); (void) kill(pid, SIGKILL); } else if (r == -EPROTO) log_debug_errno(r, "Unmounting '%s' failed abnormally, child process " PID_FMT " aborted or exited non-zero.", m->path, pid); else if (r < 0) log_error_errno(r, "Unmounting '%s' failed unexpectedly, couldn't wait for child process " PID_FMT ": %m", m->path, pid); return r; } /* This includes remounting readonly, which changes the kernel mount options. * Therefore the list passed to this function is invalidated, and should not be reused. */ static int mount_points_list_umount(MountPoint **head, bool *changed, int umount_log_level) { MountPoint *m; int n_failed = 0; assert(head); assert(changed); LIST_FOREACH(mount_point, m, *head) { if (m->try_remount_ro) { /* We always try to remount directories * read-only first, before we go on and umount * them. * * Mount points can be stacked. If a mount * point is stacked below / or /usr, we * cannot umount or remount it directly, * since there is no way to refer to the * underlying mount. There's nothing we can do * about it for the general case, but we can * do something about it if it is aliased * somehwere else via a bind mount. If we * explicitly remount the super block of that * alias read-only we hence should be * relatively safe regarding keeping a dirty fs * we cannot otherwise see. * * Since the remount can hang in the instance of * remote filesystems, we remount asynchronously * and skip the subsequent umount if it fails. */ if (remount_with_timeout(m, umount_log_level) < 0) { /* Remount failed, but try unmounting anyway, * unless this is a mount point we want to skip. */ if (nonunmountable_path(m->path)) { n_failed++; continue; } } } /* Skip / and /usr since we cannot unmount that * anyway, since we are running from it. They have * already been remounted ro. */ if (nonunmountable_path(m->path)) continue; /* Trying to umount */ if (umount_with_timeout(m, umount_log_level) < 0) n_failed++; else *changed = true; } return n_failed; } static int swap_points_list_off(MountPoint **head, bool *changed) { MountPoint *m, *n; int n_failed = 0; assert(head); assert(changed); LIST_FOREACH_SAFE(mount_point, m, n, *head) { log_info("Deactivating swap %s.", m->path); if (swapoff(m->path) == 0) { *changed = true; mount_point_free(head, m); } else { log_warning_errno(errno, "Could not deactivate swap %s: %m", m->path); n_failed++; } } return n_failed; } static int loopback_points_list_detach(MountPoint **head, bool *changed, int umount_log_level) { MountPoint *m, *n; int n_failed = 0, k; struct stat root_st; assert(head); assert(changed); k = lstat("/", &root_st); LIST_FOREACH_SAFE(mount_point, m, n, *head) { int r; struct stat loopback_st; if (k >= 0 && major(root_st.st_dev) != 0 && lstat(m->path, &loopback_st) >= 0 && root_st.st_dev == loopback_st.st_rdev) { n_failed++; continue; } log_info("Detaching loopback %s.", m->path); r = delete_loopback(m->path); if (r >= 0) { if (r > 0) *changed = true; mount_point_free(head, m); } else { log_full_errno(umount_log_level, errno, "Could not detach loopback %s: %m", m->path); n_failed++; } } return n_failed; } static int dm_points_list_detach(MountPoint **head, bool *changed, int umount_log_level) { MountPoint *m, *n; int n_failed = 0, r; dev_t rootdev; assert(head); assert(changed); r = get_block_device("/", &rootdev); if (r <= 0) rootdev = 0; LIST_FOREACH_SAFE(mount_point, m, n, *head) { if (major(rootdev) != 0 && rootdev == m->devnum) { n_failed ++; continue; } log_info("Detaching DM %u:%u.", major(m->devnum), minor(m->devnum)); r = delete_dm(m->devnum); if (r >= 0) { *changed = true; mount_point_free(head, m); } else { log_full_errno(umount_log_level, errno, "Could not detach DM %s: %m", m->path); n_failed++; } } return n_failed; } static int umount_all_once(bool *changed, int umount_log_level) { int r; _cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, mp_list_head); assert(changed); LIST_HEAD_INIT(mp_list_head); r = mount_points_list_get(NULL, &mp_list_head); if (r < 0) return r; return mount_points_list_umount(&mp_list_head, changed, umount_log_level); } int umount_all(bool *changed, int umount_log_level) { bool umount_changed; int r; assert(changed); /* Retry umount, until nothing can be umounted anymore. Mounts are * processed in order, newest first. The retries are needed when * an old mount has been moved, to a path inside a newer mount. */ do { umount_changed = false; r = umount_all_once(&umount_changed, umount_log_level); if (umount_changed) *changed = true; } while (umount_changed); return r; } int swapoff_all(bool *changed) { _cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, swap_list_head); int r; assert(changed); LIST_HEAD_INIT(swap_list_head); r = swap_list_get(NULL, &swap_list_head); if (r < 0) return r; return swap_points_list_off(&swap_list_head, changed); } int loopback_detach_all(bool *changed, int umount_log_level) { _cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, loopback_list_head); int r; assert(changed); LIST_HEAD_INIT(loopback_list_head); r = loopback_list_get(&loopback_list_head); if (r < 0) return r; return loopback_points_list_detach(&loopback_list_head, changed, umount_log_level); } int dm_detach_all(bool *changed, int umount_log_level) { _cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, dm_list_head); int r; assert(changed); LIST_HEAD_INIT(dm_list_head); r = dm_list_get(&dm_list_head); if (r < 0) return r; return dm_points_list_detach(&dm_list_head, changed, umount_log_level); }