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-rw-r--r--src/core/umount.c699
1 files changed, 699 insertions, 0 deletions
diff --git a/src/core/umount.c b/src/core/umount.c
new file mode 100644
index 0000000..7af0195
--- /dev/null
+++ b/src/core/umount.c
@@ -0,0 +1,699 @@
+/* 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 "mountpoint-util.h"
+#include "path-util.h"
+#include "process-util.h"
+#include "signal-util.h"
+#include "string-util.h"
+#include "strv.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_SET(p, "/dev", "/sys", "/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);
+}
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