1 /* SPDX-License-Identifier: LGPL-2.1+ */
3 Copyright © 2010 ProFUSION embedded systems
8 #include <linux/dm-ioctl.h>
9 #include <linux/loop.h>
11 #include <sys/mount.h>
14 #include <sys/types.h>
17 #include "sd-device.h"
19 #include "alloc-util.h"
20 #include "blockdev-util.h"
22 #include "device-util.h"
25 #include "fstab-util.h"
26 #include "libmount-util.h"
27 #include "mount-setup.h"
28 #include "mount-util.h"
29 #include "mountpoint-util.h"
30 #include "path-util.h"
31 #include "process-util.h"
32 #include "signal-util.h"
33 #include "string-util.h"
39 static void mount_point_free(MountPoint
**head
, MountPoint
*m
) {
43 LIST_REMOVE(mount_point
, *head
, m
);
46 free(m
->remount_options
);
50 void mount_points_list_free(MountPoint
**head
) {
54 mount_point_free(head
, *head
);
57 int mount_points_list_get(const char *mountinfo
, MountPoint
**head
) {
58 _cleanup_(mnt_free_tablep
) struct libmnt_table
*table
= NULL
;
59 _cleanup_(mnt_free_iterp
) struct libmnt_iter
*iter
= NULL
;
64 r
= libmount_parse(mountinfo
, NULL
, &table
, &iter
);
66 return log_error_errno(r
, "Failed to parse %s: %m", mountinfo
);
70 const char *path
, *fstype
;
71 _cleanup_free_
char *options
= NULL
;
72 unsigned long remount_flags
= 0u;
73 _cleanup_free_
char *remount_options
= NULL
;
75 _cleanup_free_ MountPoint
*m
= NULL
;
77 r
= mnt_table_next_fs(table
, iter
, &fs
);
81 return log_error_errno(r
, "Failed to get next entry from %s: %m", mountinfo
);
83 path
= mnt_fs_get_target(fs
);
87 fstype
= mnt_fs_get_fstype(fs
);
89 /* Combine the generic VFS options with the FS-specific
90 * options. Duplicates are not a problem here, because the only
91 * options that should come up twice are typically ro/rw, which
92 * are turned into MS_RDONLY or the inversion of it.
94 * Even if there are duplicates later in mount_option_mangle()
95 * they shouldn't hurt anyways as they override each other.
97 if (!strextend_with_separator(&options
, ",",
98 mnt_fs_get_vfs_options(fs
),
101 if (!strextend_with_separator(&options
, ",",
102 mnt_fs_get_fs_options(fs
),
106 /* Ignore mount points we can't unmount because they
107 * are API or because we are keeping them open (like
108 * /dev/console). Also, ignore all mounts below API
109 * file systems, since they are likely virtual too,
110 * and hence not worth spending time on. Also, in
111 * unprivileged containers we might lack the rights to
112 * unmount these things, hence don't bother. */
113 if (mount_point_is_api(path
) ||
114 mount_point_ignore(path
) ||
115 PATH_STARTSWITH_SET(path
, "/dev", "/sys", "/proc"))
118 /* If we are in a container, don't attempt to
119 * read-only mount anything as that brings no real
120 * benefits, but might confuse the host, as we remount
121 * the superblock here, not the bind mount.
123 * If the filesystem is a network fs, also skip the
124 * remount. It brings no value (we cannot leave
125 * a "dirty fs") and could hang if the network is down.
126 * Note that umount2() is more careful and will not
127 * hang because of the network being down. */
128 try_remount_ro
= detect_container() <= 0 &&
129 !fstype_is_network(fstype
) &&
130 !fstype_is_api_vfs(fstype
) &&
131 !fstype_is_ro(fstype
) &&
132 !fstab_test_yes_no_option(options
, "ro\0rw\0");
134 if (try_remount_ro
) {
135 /* mount(2) states that mount flags and options need to be exactly the same
136 * as they were when the filesystem was mounted, except for the desired
137 * changes. So we reconstruct both here and adjust them for the later
138 * remount call too. */
140 r
= mnt_fs_get_propagation(fs
, &remount_flags
);
142 log_warning_errno(r
, "mnt_fs_get_propagation() failed for %s, ignoring: %m", path
);
146 r
= mount_option_mangle(options
, remount_flags
, &remount_flags
, &remount_options
);
148 log_warning_errno(r
, "mount_option_mangle failed for %s, ignoring: %m", path
);
152 /* MS_BIND is special. If it is provided it will only make the mount-point
153 * read-only. If left out, the super block itself is remounted, which we want. */
154 remount_flags
= (remount_flags
|MS_REMOUNT
|MS_RDONLY
) & ~MS_BIND
;
157 m
= new0(MountPoint
, 1);
161 m
->path
= strdup(path
);
165 m
->remount_options
= TAKE_PTR(remount_options
);
166 m
->remount_flags
= remount_flags
;
167 m
->try_remount_ro
= try_remount_ro
;
169 LIST_PREPEND(mount_point
, *head
, TAKE_PTR(m
));
175 int swap_list_get(const char *swaps
, MountPoint
**head
) {
176 _cleanup_(mnt_free_tablep
) struct libmnt_table
*t
= NULL
;
177 _cleanup_(mnt_free_iterp
) struct libmnt_iter
*i
= NULL
;
183 i
= mnt_new_iter(MNT_ITER_FORWARD
);
187 r
= mnt_table_parse_swaps(t
, swaps
);
189 return log_error_errno(r
, "Failed to parse %s: %m", swaps
);
192 struct libmnt_fs
*fs
;
193 _cleanup_free_ MountPoint
*swap
= NULL
;
196 r
= mnt_table_next_fs(t
, i
, &fs
);
200 return log_error_errno(r
, "Failed to get next entry from %s: %m", swaps
);
202 source
= mnt_fs_get_source(fs
);
206 swap
= new0(MountPoint
, 1);
210 swap
->path
= strdup(source
);
214 LIST_PREPEND(mount_point
, *head
, TAKE_PTR(swap
));
220 static int loopback_list_get(MountPoint
**head
) {
221 _cleanup_(sd_device_enumerator_unrefp
) sd_device_enumerator
*e
= NULL
;
227 r
= sd_device_enumerator_new(&e
);
231 r
= sd_device_enumerator_allow_uninitialized(e
);
235 r
= sd_device_enumerator_add_match_subsystem(e
, "block", true);
239 r
= sd_device_enumerator_add_match_sysname(e
, "loop*");
243 r
= sd_device_enumerator_add_match_sysattr(e
, "loop/backing_file", NULL
, true);
247 FOREACH_DEVICE(e
, d
) {
248 _cleanup_free_
char *p
= NULL
;
252 if (sd_device_get_devname(d
, &dn
) < 0)
259 lb
= new(MountPoint
, 1);
267 LIST_PREPEND(mount_point
, *head
, lb
);
273 static int dm_list_get(MountPoint
**head
) {
274 _cleanup_(sd_device_enumerator_unrefp
) sd_device_enumerator
*e
= NULL
;
280 r
= sd_device_enumerator_new(&e
);
284 r
= sd_device_enumerator_allow_uninitialized(e
);
288 r
= sd_device_enumerator_add_match_subsystem(e
, "block", true);
292 r
= sd_device_enumerator_add_match_sysname(e
, "dm-*");
296 FOREACH_DEVICE(e
, d
) {
297 _cleanup_free_
char *p
= NULL
;
302 if (sd_device_get_devnum(d
, &devnum
) < 0 ||
303 sd_device_get_devname(d
, &dn
) < 0)
310 m
= new(MountPoint
, 1);
319 LIST_PREPEND(mount_point
, *head
, m
);
325 static int delete_loopback(const char *device
) {
326 _cleanup_close_
int fd
= -1;
331 fd
= open(device
, O_RDONLY
|O_CLOEXEC
);
333 return errno
== ENOENT
? 0 : -errno
;
335 r
= ioctl(fd
, LOOP_CLR_FD
, 0);
339 /* ENXIO: not bound, so no error */
346 static int delete_dm(dev_t devnum
) {
348 struct dm_ioctl dm
= {
352 DM_VERSION_PATCHLEVEL
354 .data_size
= sizeof(dm
),
358 _cleanup_close_
int fd
= -1;
360 assert(major(devnum
) != 0);
362 fd
= open("/dev/mapper/control", O_RDWR
|O_CLOEXEC
);
366 if (ioctl(fd
, DM_DEV_REMOVE
, &dm
) < 0)
372 static bool nonunmountable_path(const char *path
) {
373 return path_equal(path
, "/")
375 || path_equal(path
, "/usr")
377 || path_startswith(path
, "/run/initramfs");
380 static int remount_with_timeout(MountPoint
*m
, int umount_log_level
) {
384 BLOCK_SIGNALS(SIGCHLD
);
388 /* Due to the possibility of a remount operation hanging, we
389 * fork a child process and set a timeout. If the timeout
390 * lapses, the assumption is that that particular remount
392 r
= safe_fork("(sd-remount)", FORK_RESET_SIGNALS
|FORK_CLOSE_ALL_FDS
|FORK_LOG
|FORK_REOPEN_LOG
, &pid
);
396 log_info("Remounting '%s' read-only in with options '%s'.", m
->path
, m
->remount_options
);
398 /* Start the mount operation here in the child */
399 r
= mount(NULL
, m
->path
, NULL
, m
->remount_flags
, m
->remount_options
);
401 log_full_errno(umount_log_level
, errno
, "Failed to remount '%s' read-only: %m", m
->path
);
403 _exit(r
< 0 ? EXIT_FAILURE
: EXIT_SUCCESS
);
406 r
= wait_for_terminate_with_timeout(pid
, DEFAULT_TIMEOUT_USEC
);
407 if (r
== -ETIMEDOUT
) {
408 log_error_errno(r
, "Remounting '%s' timed out, issuing SIGKILL to PID " PID_FMT
".", m
->path
, pid
);
409 (void) kill(pid
, SIGKILL
);
410 } else if (r
== -EPROTO
)
411 log_debug_errno(r
, "Remounting '%s' failed abnormally, child process " PID_FMT
" aborted or exited non-zero.", m
->path
, pid
);
413 log_error_errno(r
, "Remounting '%s' failed unexpectedly, couldn't wait for child process " PID_FMT
": %m", m
->path
, pid
);
418 static int umount_with_timeout(MountPoint
*m
, int umount_log_level
) {
422 BLOCK_SIGNALS(SIGCHLD
);
426 /* Due to the possibility of a umount operation hanging, we
427 * fork a child process and set a timeout. If the timeout
428 * lapses, the assumption is that that particular umount
430 r
= safe_fork("(sd-umount)", FORK_RESET_SIGNALS
|FORK_CLOSE_ALL_FDS
|FORK_LOG
|FORK_REOPEN_LOG
, &pid
);
434 log_info("Unmounting '%s'.", m
->path
);
436 /* Start the mount operation here in the child Using MNT_FORCE
437 * causes some filesystems (e.g. FUSE and NFS and other network
438 * filesystems) to abort any pending requests and return -EIO
439 * rather than blocking indefinitely. If the filesysten is
440 * "busy", this may allow processes to die, thus making the
441 * filesystem less busy so the unmount might succeed (rather
442 * then return EBUSY).*/
443 r
= umount2(m
->path
, MNT_FORCE
);
445 log_full_errno(umount_log_level
, errno
, "Failed to unmount %s: %m", m
->path
);
447 _exit(r
< 0 ? EXIT_FAILURE
: EXIT_SUCCESS
);
450 r
= wait_for_terminate_with_timeout(pid
, DEFAULT_TIMEOUT_USEC
);
451 if (r
== -ETIMEDOUT
) {
452 log_error_errno(r
, "Unmounting '%s' timed out, issuing SIGKILL to PID " PID_FMT
".", m
->path
, pid
);
453 (void) kill(pid
, SIGKILL
);
454 } else if (r
== -EPROTO
)
455 log_debug_errno(r
, "Unmounting '%s' failed abnormally, child process " PID_FMT
" aborted or exited non-zero.", m
->path
, pid
);
457 log_error_errno(r
, "Unmounting '%s' failed unexpectedly, couldn't wait for child process " PID_FMT
": %m", m
->path
, pid
);
462 /* This includes remounting readonly, which changes the kernel mount options.
463 * Therefore the list passed to this function is invalidated, and should not be reused. */
464 static int mount_points_list_umount(MountPoint
**head
, bool *changed
, int umount_log_level
) {
471 LIST_FOREACH(mount_point
, m
, *head
) {
472 if (m
->try_remount_ro
) {
473 /* We always try to remount directories
474 * read-only first, before we go on and umount
477 * Mount points can be stacked. If a mount
478 * point is stacked below / or /usr, we
479 * cannot umount or remount it directly,
480 * since there is no way to refer to the
481 * underlying mount. There's nothing we can do
482 * about it for the general case, but we can
483 * do something about it if it is aliased
484 * somewhere else via a bind mount. If we
485 * explicitly remount the super block of that
486 * alias read-only we hence should be
487 * relatively safe regarding keeping a dirty fs
488 * we cannot otherwise see.
490 * Since the remount can hang in the instance of
491 * remote filesystems, we remount asynchronously
492 * and skip the subsequent umount if it fails. */
493 if (remount_with_timeout(m
, umount_log_level
) < 0) {
494 /* Remount failed, but try unmounting anyway,
495 * unless this is a mount point we want to skip. */
496 if (nonunmountable_path(m
->path
)) {
503 /* Skip / and /usr since we cannot unmount that
504 * anyway, since we are running from it. They have
505 * already been remounted ro. */
506 if (nonunmountable_path(m
->path
))
509 /* Trying to umount */
510 if (umount_with_timeout(m
, umount_log_level
) < 0)
519 static int swap_points_list_off(MountPoint
**head
, bool *changed
) {
526 LIST_FOREACH_SAFE(mount_point
, m
, n
, *head
) {
527 log_info("Deactivating swap %s.", m
->path
);
528 if (swapoff(m
->path
) == 0) {
530 mount_point_free(head
, m
);
532 log_warning_errno(errno
, "Could not deactivate swap %s: %m", m
->path
);
540 static int loopback_points_list_detach(MountPoint
**head
, bool *changed
, int umount_log_level
) {
548 k
= lstat("/", &root_st
);
550 LIST_FOREACH_SAFE(mount_point
, m
, n
, *head
) {
552 struct stat loopback_st
;
555 major(root_st
.st_dev
) != 0 &&
556 lstat(m
->path
, &loopback_st
) >= 0 &&
557 root_st
.st_dev
== loopback_st
.st_rdev
) {
562 log_info("Detaching loopback %s.", m
->path
);
563 r
= delete_loopback(m
->path
);
568 mount_point_free(head
, m
);
570 log_full_errno(umount_log_level
, errno
, "Could not detach loopback %s: %m", m
->path
);
578 static int dm_points_list_detach(MountPoint
**head
, bool *changed
, int umount_log_level
) {
586 r
= get_block_device("/", &rootdev
);
590 LIST_FOREACH_SAFE(mount_point
, m
, n
, *head
) {
592 if (major(rootdev
) != 0 && rootdev
== m
->devnum
) {
597 log_info("Detaching DM %u:%u.", major(m
->devnum
), minor(m
->devnum
));
598 r
= delete_dm(m
->devnum
);
601 mount_point_free(head
, m
);
603 log_full_errno(umount_log_level
, errno
, "Could not detach DM %s: %m", m
->path
);
611 static int umount_all_once(bool *changed
, int umount_log_level
) {
613 _cleanup_(mount_points_list_free
) LIST_HEAD(MountPoint
, mp_list_head
);
617 LIST_HEAD_INIT(mp_list_head
);
618 r
= mount_points_list_get(NULL
, &mp_list_head
);
622 return mount_points_list_umount(&mp_list_head
, changed
, umount_log_level
);
625 int umount_all(bool *changed
, int umount_log_level
) {
631 /* Retry umount, until nothing can be umounted anymore. Mounts are
632 * processed in order, newest first. The retries are needed when
633 * an old mount has been moved, to a path inside a newer mount. */
635 umount_changed
= false;
637 r
= umount_all_once(&umount_changed
, umount_log_level
);
640 } while (umount_changed
);
645 int swapoff_all(bool *changed
) {
646 _cleanup_(mount_points_list_free
) LIST_HEAD(MountPoint
, swap_list_head
);
651 LIST_HEAD_INIT(swap_list_head
);
653 r
= swap_list_get(NULL
, &swap_list_head
);
657 return swap_points_list_off(&swap_list_head
, changed
);
660 int loopback_detach_all(bool *changed
, int umount_log_level
) {
661 _cleanup_(mount_points_list_free
) LIST_HEAD(MountPoint
, loopback_list_head
);
666 LIST_HEAD_INIT(loopback_list_head
);
668 r
= loopback_list_get(&loopback_list_head
);
672 return loopback_points_list_detach(&loopback_list_head
, changed
, umount_log_level
);
675 int dm_detach_all(bool *changed
, int umount_log_level
) {
676 _cleanup_(mount_points_list_free
) LIST_HEAD(MountPoint
, dm_list_head
);
681 LIST_HEAD_INIT(dm_list_head
);
683 r
= dm_list_get(&dm_list_head
);
687 return dm_points_list_detach(&dm_list_head
, changed
, umount_log_level
);