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dissect: Add systemd-dissect --umount

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This command takes a mountpoint, unmounts it and makes sure the
underlying partition devices and block device are removed before
exiting.

To mirror the --mount operation, we also add a --rmdir option which
does the opposite of --mkdir, and a -U option which is a shortcut
for --umount --rmdir.
This commit is contained in:
Daan De Meyer 2022-07-28 01:55:11 +02:00
parent 35d40302af
commit ac1f1adfc6
3 changed files with 152 additions and 11 deletions
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38
man/systemd-dissect.xml
View file

@ -28,6 +28,9 @@
<cmdsynopsis>
<command>systemd-dissect <arg choice="opt" rep="repeat">OPTIONS</arg> <option>--mount</option> <arg choice="plain"><replaceable>IMAGE</replaceable></arg> <arg choice="plain"><replaceable>PATH</replaceable></arg></command>
</cmdsynopsis>
<cmdsynopsis>
<command>systemd-dissect <arg choice="opt" rep="repeat">OPTIONS</arg> <option>--umount</option> <arg choice="plain"><replaceable>PATH</replaceable></arg></command>
</cmdsynopsis>
<cmdsynopsis>
<command>systemd-dissect <arg choice="opt" rep="repeat">OPTIONS</arg> <option>--copy-from</option> <arg choice="plain"><replaceable>IMAGE</replaceable></arg> <arg choice="plain"><replaceable>PATH</replaceable></arg> <arg choice="opt"><replaceable>TARGET</replaceable></arg></command>
</cmdsynopsis>
@ -40,7 +43,7 @@
<title>Description</title>
<para><command>systemd-dissect</command> is a tool for introspecting and interacting with file system OS
disk images. It supports four different operations:</para>
disk images. It supports five different operations:</para>
<orderedlist>
<listitem><para>Show general OS image information, including the image's
@ -51,6 +54,10 @@
mount the included partitions according to their designation onto a directory and possibly
sub-directories.</para></listitem>
<listitem><para>Unmount an OS image from a local directory. In this mode it will recursively unmount
the mounted partitions and remove the underlying loop device, including all the partition sub-devices.
</para></listitem>
<listitem><para>Copy files and directories in and out of an OS image.</para></listitem>
</orderedlist>
@ -103,10 +110,7 @@
multiple nested mounts are established. This command expects two arguments: a path to an image file
and a path to a directory where to mount the image.</para>
<para>To unmount an OS image mounted like this use <citerefentry
project='man-pages'><refentrytitle>umount</refentrytitle><manvolnum>8</manvolnum></citerefentry>'s
<option>-R</option> switch (for recursive operation), so that the OS image and all nested partition
mounts are unmounted.</para>
<para>To unmount an OS image mounted like this use the <option>--umount</option> operation.</para>
<para>When the OS image contains LUKS encrypted or Verity integrity protected file systems
appropriate volumes are automatically set up and marked for automatic disassembly when the image is
@ -128,6 +132,23 @@
<listitem><para>This is a shortcut for <option>--mount --mkdir</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--umount</option></term>
<term><option>-u</option></term>
<listitem><para>Unmount an OS image from the specified directory. This command expects one argument:
a directory where an OS image was mounted.</para>
<para>All mounted partitions will be recursively unmounted, and the underlying loop device will be
removed, along with all it's partition sub-devices.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>-U</option></term>
<listitem><para>This is a shortcut for <option>--umount --rmdir</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--copy-from</option></term>
<term><option>-x</option></term>
@ -224,6 +245,13 @@
unmounted again.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--rmdir</option></term>
<listitem><para>If combined with <option>--umount</option> the specified directory where the OS image
is mounted is removed after unmounting the OS image.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--discard=</option></term>

115
src/dissect/dissect.c
View file

@ -8,7 +8,10 @@
#include <sys/ioctl.h>
#include <sys/mount.h>
#include "sd-device.h"
#include "architecture.h"
#include "blockdev-util.h"
#include "chase-symlinks.h"
#include "copy.h"
#include "dissect-image.h"
@ -24,6 +27,7 @@
#include "main-func.h"
#include "mkdir.h"
#include "mount-util.h"
#include "mountpoint-util.h"
#include "namespace-util.h"
#include "parse-argument.h"
#include "parse-util.h"
@ -40,6 +44,7 @@
static enum {
ACTION_DISSECT,
ACTION_MOUNT,
ACTION_UMOUNT,
ACTION_COPY_FROM,
ACTION_COPY_TO,
} arg_action = ACTION_DISSECT;
@ -58,6 +63,7 @@ static VeritySettings arg_verity_settings = VERITY_SETTINGS_DEFAULT;
static JsonFormatFlags arg_json_format_flags = JSON_FORMAT_OFF;
static PagerFlags arg_pager_flags = 0;
static bool arg_legend = true;
static bool arg_rmdir = false;
STATIC_DESTRUCTOR_REGISTER(arg_verity_settings, verity_settings_done);
@ -81,6 +87,7 @@ static int help(void) {
" --fsck=BOOL Run fsck before mounting\n"
" --growfs=BOOL Grow file system to partition size, if marked\n"
" --mkdir Make mount directory before mounting, if missing\n"
" --rmdir Remove mount directory after unmounting\n"
" --discard=MODE Choose 'discard' mode (disabled, loop, all, crypto)\n"
" --root-hash=HASH Specify root hash for verity\n"
" --root-hash-sig=SIG Specify pkcs7 signature of root hash for verity\n"
@ -96,6 +103,8 @@ static int help(void) {
" --version Show package version\n"
" -m --mount Mount the image to the specified directory\n"
" -M Shortcut for --mount --mkdir\n"
" -u --umount Unmount the image from the specified directory\n"
" -U Shortcut for --umount --rmdir\n"
" -x --copy-from Copy files from image to host\n"
" -a --copy-to Copy files from host to image\n"
"\nSee the %2$s for details.\n",
@ -122,6 +131,7 @@ static int parse_argv(int argc, char *argv[]) {
ARG_ROOT_HASH_SIG,
ARG_VERITY_DATA,
ARG_MKDIR,
ARG_RMDIR,
ARG_JSON,
};
@ -131,6 +141,7 @@ static int parse_argv(int argc, char *argv[]) {
{ "no-pager", no_argument, NULL, ARG_NO_PAGER },
{ "no-legend", no_argument, NULL, ARG_NO_LEGEND },
{ "mount", no_argument, NULL, 'm' },
{ "umount", no_argument, NULL, 'u' },
{ "read-only", no_argument, NULL, 'r' },
{ "discard", required_argument, NULL, ARG_DISCARD },
{ "fsck", required_argument, NULL, ARG_FSCK },
@ -139,6 +150,7 @@ static int parse_argv(int argc, char *argv[]) {
{ "root-hash-sig", required_argument, NULL, ARG_ROOT_HASH_SIG },
{ "verity-data", required_argument, NULL, ARG_VERITY_DATA },
{ "mkdir", no_argument, NULL, ARG_MKDIR },
{ "rmdir", no_argument, NULL, ARG_RMDIR },
{ "copy-from", no_argument, NULL, 'x' },
{ "copy-to", no_argument, NULL, 'a' },
{ "json", required_argument, NULL, ARG_JSON },
@ -150,7 +162,7 @@ static int parse_argv(int argc, char *argv[]) {
assert(argc >= 0);
assert(argv);
while ((c = getopt_long(argc, argv, "hmrMxa", options, NULL)) >= 0) {
while ((c = getopt_long(argc, argv, "hmurMUxa", options, NULL)) >= 0) {
switch (c) {
@ -182,6 +194,20 @@ static int parse_argv(int argc, char *argv[]) {
arg_flags |= DISSECT_IMAGE_MKDIR;
break;
case 'u':
arg_action = ACTION_UMOUNT;
break;
case ARG_RMDIR:
arg_rmdir = true;
break;
case 'U':
/* Shortcut combination of the above two */
arg_action = ACTION_UMOUNT;
arg_rmdir = true;
break;
case 'x':
arg_action = ACTION_COPY_FROM;
arg_flags |= DISSECT_IMAGE_READ_ONLY;
@ -316,6 +342,14 @@ static int parse_argv(int argc, char *argv[]) {
arg_flags |= DISSECT_IMAGE_REQUIRE_ROOT;
break;
case ACTION_UMOUNT:
if (optind + 1 != argc)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"Expected a mount point path as only argument.");
arg_path = argv[optind];
break;
case ACTION_COPY_FROM:
if (argc < optind + 2 || argc > optind + 3)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
@ -823,6 +857,82 @@ static int action_copy(DissectedImage *m, LoopDevice *d) {
return 0;
}
static int action_umount(const char *path) {
_cleanup_close_ int fd = -1;
_cleanup_free_ char *canonical = NULL;
dev_t devno;
const char *devname;
_cleanup_(loop_device_unrefp) LoopDevice *d = NULL;
_cleanup_(sd_device_unrefp) sd_device *device = NULL;
int r, k;
fd = chase_symlinks_and_open(path, NULL, 0, O_DIRECTORY, &canonical);
if (fd == -ENOTDIR)
return log_error_errno(SYNTHETIC_ERRNO(ENOTDIR), "'%s' is not a directory", path);
if (fd < 0)
return log_error_errno(fd, "Failed to resolve path '%s': %m", path);
r = fd_is_mount_point(fd, NULL, 0);
if (r == 0)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "'%s' is not a mount point", canonical);
if (r < 0)
return log_error_errno(r, "Failed to determine whether '%s' is a mount point: %m", canonical);
r = fd_get_whole_disk(fd, /*backing=*/ true, &devno);
if (r < 0)
return log_error_errno(r, "Failed to find backing block device for '%s': %m", canonical);
r = sd_device_new_from_devnum(&device, 'b', devno);
if (r < 0)
return log_error_errno(r, "Failed to create sd-device object for block device %u:%u: %m",
major(devno), minor(devno));
r = sd_device_get_devname(device, &devname);
if (r < 0)
return log_error_errno(r, "Failed to get devname of block device %u:%u: %m",
major(devno), minor(devno));
r = loop_device_open(devname, 0, &d);
if (r < 0)
return log_error_errno(r, "Failed to open loop device '%s': %m", devname);
r = loop_device_flock(d, LOCK_EX);
if (r < 0)
return log_error_errno(r, "Failed to lock loop device '%s': %m", devname);
/* We've locked the loop device, now we're ready to unmount. To allow the unmount to succeed, we have
* to close the O_PATH fd we opened earlier. */
fd = safe_close(fd);
r = umount_recursive(canonical, 0);
if (r < 0)
return log_error_errno(r, "Failed to unmount '%s': %m", canonical);
/* We managed to lock and unmount successfully? That means we can try to remove the loop device.*/
loop_device_unrelinquish(d);
if (arg_rmdir) {
k = RET_NERRNO(rmdir(canonical));
if (k < 0)
log_error_errno(k, "Failed to remove mount directory '%s': %m", canonical);
} else
k = 0;
/* Before loop_device_unrefp() kicks in, let's explicitly remove all the partition subdevices of the
* loop device. We do this to ensure that all traces of the loop device are gone by the time this
* command exits. */
r = block_device_remove_all_partitions(d->fd);
if (r == -EBUSY) {
log_error_errno(r, "One or more partitions of '%s' are busy, ignoring", devname);
r = 0;
}
if (r < 0)
log_error_errno(r, "Failed to remove one or more partitions of '%s': %m", devname);
return k < 0 ? k : r;
}
static int run(int argc, char *argv[]) {
_cleanup_(dissected_image_unrefp) DissectedImage *m = NULL;
_cleanup_(loop_device_unrefp) LoopDevice *d = NULL;
@ -835,6 +945,9 @@ static int run(int argc, char *argv[]) {
if (r <= 0)
return r;
if (arg_action == ACTION_UMOUNT)
return action_umount(arg_path);
r = verity_settings_load(
&arg_verity_settings,
arg_image, NULL, NULL);

10
test/units/testsuite-50.sh
View file

@ -58,8 +58,8 @@ if [ "${verity_count}" -lt 1 ]; then
echo "Verity device ${image}.raw not found in /dev/mapper/"
exit 1
fi
umount "${image_dir}/mount"
umount "${image_dir}/mount2"
systemd-dissect --umount "${image_dir}/mount"
systemd-dissect --umount "${image_dir}/mount2"
systemd-run -P -p RootImage="${image}.raw" cat /usr/lib/os-release | grep -q -F "MARKER=1"
mv "${image}.verity" "${image}.fooverity"
@ -207,7 +207,7 @@ systemd-dissect --root-hash "${roothash}" --mount "${image}.gpt" "${image_dir}/m
grep -q -F -f "$os_release" "${image_dir}/mount/usr/lib/os-release"
grep -q -F -f "$os_release" "${image_dir}/mount/etc/os-release"
grep -q -F "MARKER=1" "${image_dir}/mount/usr/lib/os-release"
umount "${image_dir}/mount"
systemd-dissect --umount "${image_dir}/mount"
# add explicit -p MountAPIVFS=yes once to test the parser
systemd-run -P -p RootImage="${image}.gpt" -p RootHash="${roothash}" -p MountAPIVFS=yes cat /usr/lib/os-release | grep -q -F "MARKER=1"
@ -350,8 +350,8 @@ RemainAfterExit=yes
EOF
systemctl start testservice-50f.service
systemctl is-active testservice-50f.service
umount "${image_dir}/app0"
umount "${image_dir}/app1"
systemd-dissect --umount "${image_dir}/app0"
systemd-dissect --umount "${image_dir}/app1"
echo OK >/testok