blob: 8a5e80eeaa15a8e77334bbf920d6c8bf22a96141 [file] [log] [blame] [raw]
/* SPDX-License-Identifier: LGPL-2.1+ */
/***
Copyright © 2010 ProFUSION embedded systems
***/
#include <errno.h>
#include <fcntl.h>
#include <linux/dm-ioctl.h>
#include <linux/loop.h>
#include <sys/mount.h>
#include <sys/swap.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.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 "libmount-util.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"
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 *table = NULL;
_cleanup_(mnt_free_iterp) struct libmnt_iter *iter = NULL;
int r;
assert(head);
r = libmount_parse(mountinfo, NULL, &table, &iter);
if (r < 0)
return log_error_errno(r, "Failed to parse %s: %m", mountinfo ?: "/proc/self/mountinfo");
for (;;) {
struct libmnt_fs *fs;
const char *path, *fstype;
_cleanup_free_ char *options = NULL;
unsigned long remount_flags = 0u;
_cleanup_free_ char *remount_options = NULL;
bool try_remount_ro;
_cleanup_free_ MountPoint *m = NULL;
r = mnt_table_next_fs(table, iter, &fs);
if (r == 1)
break;
if (r < 0)
return log_error_errno(r, "Failed to get next entry from %s: %m", mountinfo ?: "/proc/self/mountinfo");
path = mnt_fs_get_target(fs);
if (!path)
continue;
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 inversion of it.
*
* Even if there are duplicates later in mount_option_mangle()
* they 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(path) ||
mount_point_ignore(path) ||
PATH_STARTSWITH_SET(path, "/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();
m->path = strdup(path);
if (!m->path)
return log_oom();
m->remount_options = TAKE_PTR(remount_options);
m->remount_flags = remount_flags;
m->try_remount_ro = try_remount_ro;
LIST_PREPEND(mount_point, *head, TAKE_PTR(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 == -ENOENT) /* no /proc/swaps is fine */
return 0;
if (r < 0)
return log_error_errno(r, "Failed to parse %s: %m", swaps ?: "/proc/swaps");
for (;;) {
struct libmnt_fs *fs;
_cleanup_free_ MountPoint *swap = NULL;
const char *source;
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 ?: "/proc/swaps");
source = mnt_fs_get_source(fs);
if (!source)
continue;
swap = new0(MountPoint, 1);
if (!swap)
return log_oom();
swap->path = strdup(source);
if (!swap->path)
return log_oom();
LIST_PREPEND(mount_point, *head, TAKE_PTR(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;
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;
lb = new(MountPoint, 1);
if (!lb)
return -ENOMEM;
*lb = (MountPoint) {
.path = TAKE_PTR(p),
.devnum = devnum,
};
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;
struct loop_info64 info;
assert(device);
fd = open(device, O_RDONLY|O_CLOEXEC);
if (fd < 0)
return errno == ENOENT ? 0 : -errno;
if (ioctl(fd, LOOP_CLR_FD, 0) < 0) {
if (errno == ENXIO) /* Nothing bound, didn't do anything */
return 0;
if (errno != EBUSY)
return log_debug_errno(errno, "Failed to clear loopback device %s: %m", device);
if (ioctl(fd, LOOP_GET_STATUS64, &info) < 0) {
if (errno == ENXIO) /* What? Suddenly detached after all? That's fine by us then. */
return 1;
log_debug_errno(errno, "Failed to invoke LOOP_GET_STATUS64 on loopback device %s, ignoring: %m", device);
return -EBUSY; /* propagate original error */
}
if (FLAGS_SET(info.lo_flags, LO_FLAGS_AUTOCLEAR)) /* someone else already set LO_FLAGS_AUTOCLEAR for us? fine by us */
return -EBUSY; /* propagate original error */
info.lo_flags |= LO_FLAGS_AUTOCLEAR;
if (ioctl(fd, LOOP_SET_STATUS64, &info) < 0) {
if (errno == ENXIO) /* Suddenly detached after all? Fine by us */
return 1;
log_debug_errno(errno, "Failed to set LO_FLAGS_AUTOCLEAR flag for loop device %s, ignoring: %m", device);
} else
log_debug("Successfully set LO_FLAGS_AUTOCLEAR flag for loop device %s.", device);
return -EBUSY;
}
if (ioctl(fd, LOOP_GET_STATUS64, &info) < 0) {
/* If the LOOP_CLR_FD above succeeded we'll see ENXIO here. */
if (errno == ENXIO)
log_debug("Successfully detached loopback device %s.", device);
else
log_debug_errno(errno, "Failed to invoke LOOP_GET_STATUS64 on loopback device %s, ignoring: %m", device); /* the LOOP_CLR_FD at least worked, let's hope for the best */
return 1;
}
/* Linux makes LOOP_CLR_FD succeed whenever LO_FLAGS_AUTOCLEAR is set without actually doing
* anything. Very confusing. Let's hence not claim we did anything in this case. */
if (FLAGS_SET(info.lo_flags, LO_FLAGS_AUTOCLEAR))
log_debug("Successfully called LOOP_CLR_FD on a loopback device %s with autoclear set, which is a NOP.", device);
else
log_debug("Weird, LOOP_CLR_FD succeeded but the device is still attached on %s.", device);
return -EBUSY; /* Nothing changed, the device is still attached, hence it apparently is still busy */
}
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 possibility 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 possibility 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 somewhere 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) {
log_warning_errno(errno, "Could not deactivate swap %s: %m", m->path);
n_failed++;
continue;
}
*changed = true;
mount_point_free(head, m);
}
return n_failed;
}
static int loopback_points_list_detach(MountPoint **head, bool *changed, int umount_log_level) {
MountPoint *m, *n;
int n_failed = 0, r;
dev_t rootdev = 0;
assert(head);
assert(changed);
(void) get_block_device("/", &rootdev);
LIST_FOREACH_SAFE(mount_point, m, n, *head) {
if (major(rootdev) != 0 && rootdev == m->devnum) {
n_failed++;
continue;
}
log_info("Detaching loopback %s.", m->path);
r = delete_loopback(m->path);
if (r < 0) {
log_full_errno(umount_log_level, r, "Could not detach loopback %s: %m", m->path);
n_failed++;
continue;
}
if (r > 0)
*changed = true;
mount_point_free(head, m);
}
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 = 0;
assert(head);
assert(changed);
(void) get_block_device("/", &rootdev);
LIST_FOREACH_SAFE(mount_point, m, n, *head) {
if (major(rootdev) != 0 && rootdev == m->devnum) {
n_failed ++;
continue;
}
log_info("Detaching DM %s (%u:%u).", m->path, major(m->devnum), minor(m->devnum));
r = delete_dm(m->devnum);
if (r < 0) {
log_full_errno(umount_log_level, r, "Could not detach DM %s: %m", m->path);
n_failed++;
continue;
}
*changed = true;
mount_point_free(head, m);
}
return n_failed;
}
static int umount_all_once(bool *changed, int umount_log_level) {
_cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, mp_list_head);
int r;
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);
}