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systemd/src/core/umount.c
Joel Holdsworth 04a9393122 core/mount: Don't unmount initramfs mounts 
A mount within /run/initramfs is indicative that the mount was
created by initramfs init and will be unmounted by initramfs
shutdown.

It is unlikely that such a mount point would even be unmountable
by the the main system, for example in the case of the root file-
system being loop-mounted from a file in a /run/initramfs mount.
2016-03-04 15:16:34 +00:00

615 lines
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/***
This file is part of systemd.
Copyright 2010 ProFUSION embedded systems
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <errno.h>
#include <fcntl.h>
#include <linux/dm-ioctl.h>
#include <linux/loop.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/swap.h>
#include "libudev.h"
#include "alloc-util.h"
#include "escape.h"
#include "fd-util.h"
#include "fstab-util.h"
#include "list.h"
#include "mount-setup.h"
#include "path-util.h"
#include "string-util.h"
#include "udev-util.h"
#include "umount.h"
#include "util.h"
#include "virt.h"
typedef struct MountPoint {
char *path;
char *options;
dev_t devnum;
LIST_FIELDS(struct MountPoint, mount_point);
} MountPoint;
static void mount_point_free(MountPoint **head, MountPoint *m) {
assert(head);
assert(m);
LIST_REMOVE(mount_point, *head, m);
free(m->path);
free(m);
}
static void mount_points_list_free(MountPoint **head) {
assert(head);
while (*head)
mount_point_free(head, *head);
}
static int mount_points_list_get(MountPoint **head) {
_cleanup_fclose_ FILE *proc_self_mountinfo = NULL;
unsigned int i;
int r;
assert(head);
proc_self_mountinfo = fopen("/proc/self/mountinfo", "re");
if (!proc_self_mountinfo)
return -errno;
for (i = 1;; i++) {
_cleanup_free_ char *path = NULL, *options = NULL;
char *p = NULL;
MountPoint *m;
int k;
k = fscanf(proc_self_mountinfo,
"%*s " /* (1) mount id */
"%*s " /* (2) parent id */
"%*s " /* (3) major:minor */
"%*s " /* (4) root */
"%ms " /* (5) mount point */
"%*s" /* (6) mount flags */
"%*[^-]" /* (7) optional fields */
"- " /* (8) separator */
"%*s " /* (9) file system type */
"%*s" /* (10) mount source */
"%ms" /* (11) mount options */
"%*[^\n]", /* some rubbish at the end */
&path, &options);
if (k != 2) {
if (k == EOF)
break;
log_warning("Failed to parse /proc/self/mountinfo:%u.", i);
continue;
}
r = cunescape(path, UNESCAPE_RELAX, &p);
if (r < 0)
return r;
/* 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")) {
free(p);
continue;
}
m = new0(MountPoint, 1);
if (!m) {
free(p);
return -ENOMEM;
}
m->path = p;
m->options = options;
options = NULL;
LIST_PREPEND(mount_point, *head, m);
}
return 0;
}
static int swap_list_get(MountPoint **head) {
_cleanup_fclose_ FILE *proc_swaps = NULL;
unsigned int i;
int r;
assert(head);
proc_swaps = fopen("/proc/swaps", "re");
if (!proc_swaps)
return (errno == ENOENT) ? 0 : -errno;
(void) fscanf(proc_swaps, "%*s %*s %*s %*s %*s\n");
for (i = 2;; i++) {
MountPoint *swap;
char *dev = NULL, *d;
int k;
k = fscanf(proc_swaps,
"%ms " /* device/file */
"%*s " /* type of swap */
"%*s " /* swap size */
"%*s " /* used */
"%*s\n", /* priority */
&dev);
if (k != 1) {
if (k == EOF)
break;
log_warning("Failed to parse /proc/swaps:%u.", i);
free(dev);
continue;
}
if (endswith(dev, " (deleted)")) {
free(dev);
continue;
}
r = cunescape(dev, UNESCAPE_RELAX, &d);
free(dev);
if (r < 0)
return r;
swap = new0(MountPoint, 1);
if (!swap) {
free(d);
return -ENOMEM;
}
swap->path = d;
LIST_PREPEND(mount_point, *head, swap);
}
return 0;
}
static int loopback_list_get(MountPoint **head) {
_cleanup_udev_enumerate_unref_ struct udev_enumerate *e = NULL;
struct udev_list_entry *item = NULL, *first = NULL;
_cleanup_udev_unref_ struct udev *udev = NULL;
int r;
assert(head);
udev = udev_new();
if (!udev)
return -ENOMEM;
e = udev_enumerate_new(udev);
if (!e)
return -ENOMEM;
r = udev_enumerate_add_match_subsystem(e, "block");
if (r < 0)
return r;
r = udev_enumerate_add_match_sysname(e, "loop*");
if (r < 0)
return r;
r = udev_enumerate_add_match_sysattr(e, "loop/backing_file", NULL);
if (r < 0)
return r;
r = udev_enumerate_scan_devices(e);
if (r < 0)
return r;
first = udev_enumerate_get_list_entry(e);
udev_list_entry_foreach(item, first) {
MountPoint *lb;
_cleanup_udev_device_unref_ struct udev_device *d;
char *loop;
const char *dn;
d = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item));
if (!d)
return -ENOMEM;
dn = udev_device_get_devnode(d);
if (!dn)
continue;
loop = strdup(dn);
if (!loop)
return -ENOMEM;
lb = new0(MountPoint, 1);
if (!lb) {
free(loop);
return -ENOMEM;
}
lb->path = loop;
LIST_PREPEND(mount_point, *head, lb);
}
return 0;
}
static int dm_list_get(MountPoint **head) {
_cleanup_udev_enumerate_unref_ struct udev_enumerate *e = NULL;
struct udev_list_entry *item = NULL, *first = NULL;
_cleanup_udev_unref_ struct udev *udev = NULL;
int r;
assert(head);
udev = udev_new();
if (!udev)
return -ENOMEM;
e = udev_enumerate_new(udev);
if (!e)
return -ENOMEM;
r = udev_enumerate_add_match_subsystem(e, "block");
if (r < 0)
return r;
r = udev_enumerate_add_match_sysname(e, "dm-*");
if (r < 0)
return r;
r = udev_enumerate_scan_devices(e);
if (r < 0)
return r;
first = udev_enumerate_get_list_entry(e);
udev_list_entry_foreach(item, first) {
MountPoint *m;
_cleanup_udev_device_unref_ struct udev_device *d;
dev_t devnum;
char *node;
const char *dn;
d = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item));
if (!d)
return -ENOMEM;
devnum = udev_device_get_devnum(d);
dn = udev_device_get_devnode(d);
if (major(devnum) == 0 || !dn)
continue;
node = strdup(dn);
if (!node)
return -ENOMEM;
m = new(MountPoint, 1);
if (!m) {
free(node);
return -ENOMEM;
}
m->path = node;
m->devnum = devnum;
LIST_PREPEND(mount_point, *head, m);
}
return 0;
}
static int delete_loopback(const char *device) {
_cleanup_close_ int fd = -1;
int r;
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) {
_cleanup_close_ int fd = -1;
int r;
struct dm_ioctl dm = {
.version = {DM_VERSION_MAJOR,
DM_VERSION_MINOR,
DM_VERSION_PATCHLEVEL},
.data_size = sizeof(dm),
.dev = devnum,
};
assert(major(devnum) != 0);
fd = open("/dev/mapper/control", O_RDWR|O_CLOEXEC);
if (fd < 0)
return -errno;
r = ioctl(fd, DM_DEV_REMOVE, &dm);
return r >= 0 ? 0 : -errno;
}
static int mount_points_list_umount(MountPoint **head, bool *changed, bool log_error) {
MountPoint *m, *n;
int n_failed = 0;
assert(head);
LIST_FOREACH_SAFE(mount_point, m, n, *head) {
/* 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 mound. */
if (detect_container() <= 0) {
_cleanup_free_ char *options = NULL;
/* MS_REMOUNT requires that the data parameter
* should be the same from the original mount
* except for the desired changes. Since we want
* to remount read-only, we should filter out
* rw (and ro too, because it confuses the kernel) */
(void) fstab_filter_options(m->options, "rw\0ro\0", NULL, NULL, &options);
/* 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 the fs we
* can otherwise not see dirty. */
log_info("Remounting '%s' read-only with options '%s'.", m->path, options);
(void) mount(NULL, m->path, NULL, MS_REMOUNT|MS_RDONLY, options);
}
/* Skip / and /usr since we cannot unmount that
* anyway, since we are running from it. They have
* already been remounted ro. */
if (path_equal(m->path, "/")
#ifndef HAVE_SPLIT_USR
|| path_equal(m->path, "/usr")
#endif
|| path_startswith(m->path, "/run/initramfs")
)
continue;
/* Trying to umount. We don't force here since we rely
* on busy NFS and FUSE file systems to return EBUSY
* until we closed everything on top of them. */
log_info("Unmounting %s.", m->path);
if (umount2(m->path, 0) == 0) {
if (changed)
*changed = true;
mount_point_free(head, m);
} else if (log_error) {
log_warning_errno(errno, "Could not unmount %s: %m", m->path);
n_failed++;
}
}
return n_failed;
}
static int swap_points_list_off(MountPoint **head, bool *changed) {
MountPoint *m, *n;
int n_failed = 0;
assert(head);
LIST_FOREACH_SAFE(mount_point, m, n, *head) {
log_info("Deactivating swap %s.", m->path);
if (swapoff(m->path) == 0) {
if (changed)
*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) {
MountPoint *m, *n;
int n_failed = 0, k;
struct stat root_st;
assert(head);
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)
*changed = true;
mount_point_free(head, m);
} else {
log_warning_errno(errno, "Could not detach loopback %s: %m", m->path);
n_failed++;
}
}
return n_failed;
}
static int dm_points_list_detach(MountPoint **head, bool *changed) {
MountPoint *m, *n;
int n_failed = 0, k;
struct stat root_st;
assert(head);
k = lstat("/", &root_st);
LIST_FOREACH_SAFE(mount_point, m, n, *head) {
int r;
if (k >= 0 &&
major(root_st.st_dev) != 0 &&
root_st.st_dev == 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) {
if (changed)
*changed = true;
mount_point_free(head, m);
} else {
log_warning_errno(errno, "Could not detach DM %s: %m", m->path);
n_failed++;
}
}
return n_failed;
}
int umount_all(bool *changed) {
int r;
bool umount_changed;
LIST_HEAD(MountPoint, mp_list_head);
LIST_HEAD_INIT(mp_list_head);
r = mount_points_list_get(&mp_list_head);
if (r < 0)
goto end;
/* retry umount, until nothing can be umounted anymore */
do {
umount_changed = false;
mount_points_list_umount(&mp_list_head, &umount_changed, false);
if (umount_changed)
*changed = true;
} while (umount_changed);
/* umount one more time with logging enabled */
r = mount_points_list_umount(&mp_list_head, &umount_changed, true);
if (r <= 0)
goto end;
end:
mount_points_list_free(&mp_list_head);
return r;
}
int swapoff_all(bool *changed) {
int r;
LIST_HEAD(MountPoint, swap_list_head);
LIST_HEAD_INIT(swap_list_head);
r = swap_list_get(&swap_list_head);
if (r < 0)
goto end;
r = swap_points_list_off(&swap_list_head, changed);
end:
mount_points_list_free(&swap_list_head);
return r;
}
int loopback_detach_all(bool *changed) {
int r;
LIST_HEAD(MountPoint, loopback_list_head);
LIST_HEAD_INIT(loopback_list_head);
r = loopback_list_get(&loopback_list_head);
if (r < 0)
goto end;
r = loopback_points_list_detach(&loopback_list_head, changed);
end:
mount_points_list_free(&loopback_list_head);
return r;
}
int dm_detach_all(bool *changed) {
int r;
LIST_HEAD(MountPoint, dm_list_head);
LIST_HEAD_INIT(dm_list_head);
r = dm_list_get(&dm_list_head);
if (r < 0)
goto end;
r = dm_points_list_detach(&dm_list_head, changed);
end:
mount_points_list_free(&dm_list_head);
return r;
}
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