Merge pull request #16604 from poettering/tmpfiles-image

add --image= switch to tmpfiles, sysusers, journalctl

TODO

@@ -120,9 +120,9 @@ Features:
   this, it's useful to have one that can dump contents of them, too.
 
 * All tools that support --root= should also learn --image= so that they can
-  operate on disk images directly. Specifically: bootctl, tmpfiles, sysusers,
-  systemctl, repart, journalctl, coredumpctl. (Already done: systemd-nspawn,
-  systemd-firstboot)
+  operate on disk images directly. Specifically: bootctl, systemctl,
+  coredumpctl. (Already done: systemd-nspawn, systemd-firstboot,
+  systemd-repart, systemd-tmpfiles, systemd-sysusers, journalctl)
 
 * seccomp: by default mask x32 ABI system wide on x86-64. it's on its way out
 
@@ -337,9 +337,6 @@ Features:
   right) become genuine first class citizens, and we gain automatic, sane JSON
   output for them.
 
-* systemd-firstboot: teach it dissector magic, so that you can point it to some
-  disk image and it will just set everything in it all behind the scenes.
-
 * We should probably replace /var/log/README, /etc/rc.d/README with symlinks
   that are linked to these places instead of copied. After all they are
   constant vendor data.

man/journalctl.xml

@@ -756,16 +756,29 @@
       <varlistentry>
         <term><option>--root=<replaceable>ROOT</replaceable></option></term>
 
-        <listitem><para>Takes a directory path as an argument. If
-        specified, journalctl will operate on journal directories and catalog file hierarchy
-        underneath the specified directory instead of the root
-        directory (e.g. <option>--update-catalog</option> will create
-        <filename><replaceable>ROOT</replaceable>/var/lib/systemd/catalog/database</filename>,
-        and journal files under <filename><replaceable>ROOT</replaceable>/run/journal/</filename>
-        or <filename><replaceable>ROOT</replaceable>/var/log/journal/</filename> will be displayed).
+        <listitem><para>Takes a directory path as an argument. If specified, <command>journalctl</command>
+        will operate on journal directories and catalog file hierarchy underneath the specified directory
+        instead of the root directory (e.g. <option>--update-catalog</option> will create
+        <filename><replaceable>ROOT</replaceable>/var/lib/systemd/catalog/database</filename>, and journal
+        files under <filename><replaceable>ROOT</replaceable>/run/journal/</filename> or
+        <filename><replaceable>ROOT</replaceable>/var/log/journal/</filename> will be displayed).
         </para></listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term><option>--image=<replaceable>IMAGE</replaceable></option></term>
+
+        <listitem><para>Takes a path to a disk image file or block device node. If specified,
+        <command>journalctl</command> will operate on the file system in the indicated disk image. This is
+        similar to <option>--root=</option> but operates on file systems stored in disk images or block
+        devices, thus providing an easy way to extract log data from disk images. The disk image should
+        either contain just a file system or a set of file systems within a GPT partition table, following
+        the <ulink url="https://systemd.io/DISCOVERABLE_PARTITIONS">Discoverable Partitions
+        Specification</ulink>. For further information on supported disk images, see
+        <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
+        switch of the same name.</para></listitem>
+      </varlistentry>
+
       <varlistentry>
         <term><option>--namespace=<replaceable>NAMESPACE</replaceable></option></term>
 

man/systemd-sysusers.xml

@@ -68,6 +68,19 @@
         paths. </para></listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term><option>--image=<replaceable>image</replaceable></option></term>
+
+        <listitem><para>Takes a path to a disk image file or block device node. If specified all operations
+        are applied to file system in the indicated disk image. This is similar to <option>--root=</option>
+        but operates on file systems stored in disk images or block devices. The disk image should either
+        contain just a file system or a set of file systems within a GPT partition table, following the
+        <ulink url="https://systemd.io/DISCOVERABLE_PARTITIONS">Discoverable Partitions
+        Specification</ulink>. For further information on supported disk images, see
+        <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
+        switch of the same name.</para></listitem>
+      </varlistentry>
+
       <varlistentry>
         <term><option>--replace=<replaceable>PATH</replaceable></option></term>
         <listitem><para>When this option is given, one ore more positional arguments

man/systemd-tmpfiles.xml

@@ -149,6 +149,7 @@
         the specified prefix. This option can be specified multiple
         times.</para></listitem>
       </varlistentry>
+
       <varlistentry>
         <term><option>--exclude-prefix=<replaceable>path</replaceable></option></term>
         <listitem><para>Ignore rules with paths that start with the
@@ -156,6 +157,16 @@
         times.</para></listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term><option>-E</option></term>
+        <listitem><para>A shortcut for <literal>--exclude-prefix=/dev --exclude-prefix=/proc
+        --exclude-prefix=/run --exclude-prefix=/sys</literal>, i.e. exclude the hierarchies typically backed
+        by virtual or memory file systems. This is useful in combination with <option>--root=</option>, if
+        the specified directory tree contains an OS tree without these virtual/memory file systems mounted
+        in, as it is typically not desirable to create any files and directories below these subdirectories
+        if they are supposed to be overmounted during runtime.</para></listitem>
+      </varlistentry>
+
       <varlistentry>
         <term><option>--root=<replaceable>root</replaceable></option></term>
         <listitem><para>Takes a directory path as an argument. All paths will be prefixed with the given alternate
@@ -164,7 +175,26 @@
         <para>When this option is used, the libc Name Service Switch (NSS) is bypassed for resolving users
         and groups. Instead the files <filename>/etc/passwd</filename> and <filename>/etc/group</filename>
         inside the alternate root are read directly. This means that users/groups not listed in these files
-        will not be resolved, i.e. LDAP NIS and other complex databases are not considered.</para></listitem>
+        will not be resolved, i.e. LDAP NIS and other complex databases are not considered.</para>
+
+        <para>Consider combining this with <option>-E</option> to ensure the invocation does not create files
+        or directories below mount points in the OS image operated on that are typically overmounted during
+        runtime.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><option>--image=<replaceable>image</replaceable></option></term>
+
+        <listitem><para>Takes a path to a disk image file or block device node. If specified all operations
+        are applied to file system in the indicated disk image. This is similar to <option>--root=</option>
+        but operates on file systems stored in disk images or block devices. The disk image should either
+        contain just a file system or a set of file systems within a GPT partition table, following the
+        <ulink url="https://systemd.io/DISCOVERABLE_PARTITIONS">Discoverable Partitions
+        Specification</ulink>. For further information on supported disk images, see
+        <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
+        switch of the same name.</para>
+
+        <para>Implies <option>-E</option>.</para></listitem>
       </varlistentry>
 
       <varlistentry>

src/firstboot/firstboot.c

@@ -19,7 +19,6 @@
 #include "kbd-util.h"
 #include "libcrypt-util.h"
 #include "locale-util.h"
-#include "loop-util.h"
 #include "main-func.h"
 #include "memory-util.h"
 #include "mkdir.h"
@@ -907,75 +906,6 @@ static int process_kernel_cmdline(void) {
         return 0;
 }
 
-static int setup_image(char **ret_mount_dir, LoopDevice **ret_loop_device, DecryptedImage **ret_decrypted_image) {
-        DissectImageFlags f = DISSECT_IMAGE_REQUIRE_ROOT|DISSECT_IMAGE_VALIDATE_OS|DISSECT_IMAGE_RELAX_VAR_CHECK|DISSECT_IMAGE_FSCK;
-        _cleanup_(loop_device_unrefp) LoopDevice *d = NULL;
-        _cleanup_(decrypted_image_unrefp) DecryptedImage *decrypted_image = NULL;
-        _cleanup_(dissected_image_unrefp) DissectedImage *dissected_image = NULL;
-        _cleanup_(rmdir_and_freep) char *mount_dir = NULL;
-        _cleanup_free_ char *temp = NULL;
-        int r;
-
-        if (!arg_image) {
-                *ret_mount_dir = NULL;
-                *ret_decrypted_image = NULL;
-                *ret_loop_device = NULL;
-                return 0;
-        }
-
-        assert(!arg_root);
-
-        r = tempfn_random_child(NULL, "firstboot", &temp);
-        if (r < 0)
-                return log_error_errno(r, "Failed to generate temporary mount directory: %m");
-
-        r = loop_device_make_by_path(arg_image, O_RDWR, LO_FLAGS_PARTSCAN, &d);
-        if (r < 0)
-                return log_error_errno(r, "Failed to set up loopback device: %m");
-
-        r = dissect_image_and_warn(d->fd, arg_image, NULL, 0, NULL, NULL, f, &dissected_image);
-        if (r < 0)
-                return r;
-
-        r = dissected_image_decrypt_interactively(dissected_image, NULL, NULL, 0, NULL, NULL, NULL, 0, f, &decrypted_image);
-        if (r < 0)
-                return r;
-
-        r = detach_mount_namespace();
-        if (r < 0)
-                return log_error_errno(r, "Failed to detach mount namespace: %m");
-
-        mount_dir = strdup(temp);
-        if (!mount_dir)
-                return log_oom();
-
-        r = mkdir_p(mount_dir, 0700);
-        if (r < 0) {
-                mount_dir = mfree(mount_dir);
-                return log_error_errno(r, "Failed to create mount point: %m");
-        }
-
-        r = dissected_image_mount(dissected_image, mount_dir, UID_INVALID, f);
-        if (r < 0)
-                return log_error_errno(r, "Failed to mount image: %m");
-
-        if (decrypted_image) {
-                r = decrypted_image_relinquish(decrypted_image);
-                if (r < 0)
-                        return log_error_errno(r, "Failed to relinquish DM devices: %m");
-        }
-
-        loop_device_relinquish(d);
-
-        arg_root = TAKE_PTR(temp);
-
-        *ret_mount_dir = TAKE_PTR(mount_dir);
-        *ret_decrypted_image = TAKE_PTR(decrypted_image);
-        *ret_loop_device = TAKE_PTR(d);
-
-        return 1;
-}
-
 static int help(void) {
         _cleanup_free_ char *link = NULL;
         int r;
@@ -1353,9 +1283,22 @@ static int run(int argc, char *argv[]) {
                         return 0; /* disabled */
         }
 
-        r = setup_image(&unlink_dir, &loop_device, &decrypted_image);
-        if (r < 0)
-                return r;
+        if (arg_image) {
+                assert(!arg_root);
+
+                r = mount_image_privately_interactively(
+                                arg_image,
+                                DISSECT_IMAGE_REQUIRE_ROOT|DISSECT_IMAGE_VALIDATE_OS|DISSECT_IMAGE_RELAX_VAR_CHECK|DISSECT_IMAGE_FSCK,
+                                &unlink_dir,
+                                &loop_device,
+                                &decrypted_image);
+                if (r < 0)
+                        return r;
+
+                arg_root = strdup(unlink_dir);
+                if (!arg_root)
+                        return log_oom();
+        }
 
         r = process_locale();
         if (r < 0)

src/journal/journalctl.c

@@ -31,6 +31,7 @@
 #include "chattr-util.h"
 #include "def.h"
 #include "device-private.h"
+#include "dissect-image.h"
 #include "fd-util.h"
 #include "fileio.h"
 #include "format-util.h"
@@ -51,6 +52,7 @@
 #include "logs-show.h"
 #include "memory-util.h"
 #include "mkdir.h"
+#include "mount-util.h"
 #include "mountpoint-util.h"
 #include "nulstr-util.h"
 #include "pager.h"
@@ -121,6 +123,7 @@ static bool arg_reverse = false;
 static int arg_journal_type = 0;
 static int arg_namespace_flags = 0;
 static char *arg_root = NULL;
+static char *arg_image = NULL;
 static const char *arg_machine = NULL;
 static const char *arg_namespace = NULL;
 static uint64_t arg_vacuum_size = 0;
@@ -375,6 +378,7 @@ static int help(void) {
                "  -D --directory=PATH        Show journal files from directory\n"
                "     --file=PATH             Show journal file\n"
                "     --root=ROOT             Operate on files below a root directory\n"
+               "     --image=IMAGE           Operate on files in filesystem image\n"
                "     --namespace=NAMESPACE   Show journal data from specified namespace\n"
                "     --interval=TIME         Time interval for changing the FSS sealing key\n"
                "     --verify-key=KEY        Specify FSS verification key\n"
@@ -422,6 +426,7 @@ static int parse_argv(int argc, char *argv[]) {
                 ARG_USER,
                 ARG_SYSTEM,
                 ARG_ROOT,
+                ARG_IMAGE,
                 ARG_HEADER,
                 ARG_FACILITY,
                 ARG_SETUP_KEYS,
@@ -478,6 +483,7 @@ static int parse_argv(int argc, char *argv[]) {
                 { "directory",            required_argument, NULL, 'D'                      },
                 { "file",                 required_argument, NULL, ARG_FILE                 },
                 { "root",                 required_argument, NULL, ARG_ROOT                 },
+                { "image",                required_argument, NULL, ARG_IMAGE                },
                 { "header",               no_argument,       NULL, ARG_HEADER               },
                 { "identifier",           required_argument, NULL, 't'                      },
                 { "priority",             required_argument, NULL, 'p'                      },
@@ -713,7 +719,13 @@ static int parse_argv(int argc, char *argv[]) {
                         break;
 
                 case ARG_ROOT:
-                        r = parse_path_argument_and_warn(optarg, true, &arg_root);
+                        r = parse_path_argument_and_warn(optarg, /* suppress_root= */ true, &arg_root);
+                        if (r < 0)
+                                return r;
+                        break;
+
+                case ARG_IMAGE:
+                        r = parse_path_argument_and_warn(optarg, /* suppress_root= */ false, &arg_image);
                         if (r < 0)
                                 return r;
                         break;
@@ -1043,8 +1055,8 @@ static int parse_argv(int argc, char *argv[]) {
         if (arg_follow && !arg_no_tail && !arg_since && arg_lines == ARG_LINES_DEFAULT)
                 arg_lines = 10;
 
-        if (!!arg_directory + !!arg_file + !!arg_machine + !!arg_root > 1) {
-                log_error("Please specify at most one of -D/--directory=, --file=, -M/--machine=, --root.");
+        if (!!arg_directory + !!arg_file + !!arg_machine + !!arg_root + !!arg_image > 1) {
+                log_error("Please specify at most one of -D/--directory=, --file=, -M/--machine=, --root=, --image=.");
                 return -EINVAL;
         }
 
@@ -2084,6 +2096,9 @@ static int wait_for_change(sd_journal *j, int poll_fd) {
 }
 
 int main(int argc, char *argv[]) {
+        _cleanup_(loop_device_unrefp) LoopDevice *loop_device = NULL;
+        _cleanup_(decrypted_image_unrefp) DecryptedImage *decrypted_image = NULL;
+        _cleanup_(umount_and_rmdir_and_freep) char *unlink_dir = NULL;
         bool previous_boot_id_valid = false, first_line = true, ellipsized = false, need_seek = false;
         bool use_cursor = false, after_cursor = false;
         _cleanup_(sd_journal_closep) sd_journal *j = NULL;
@@ -2101,6 +2116,24 @@ int main(int argc, char *argv[]) {
         if (r <= 0)
                 goto finish;
 
+        if (arg_image) {
+                assert(!arg_root);
+
+                r = mount_image_privately_interactively(
+                                arg_image,
+                                DISSECT_IMAGE_REQUIRE_ROOT|DISSECT_IMAGE_VALIDATE_OS|DISSECT_IMAGE_RELAX_VAR_CHECK|
+                                (arg_action == ACTION_UPDATE_CATALOG ? DISSECT_IMAGE_FSCK : DISSECT_IMAGE_READ_ONLY),
+                                &unlink_dir,
+                                &loop_device,
+                                &decrypted_image);
+                if (r < 0)
+                        return r;
+
+                arg_root = strdup(unlink_dir);
+                if (!arg_root)
+                        return log_oom();
+        }
+
         signal(SIGWINCH, columns_lines_cache_reset);
         sigbus_install();
 

src/shared/dissect-image.c

@@ -33,8 +33,10 @@
 #include "hexdecoct.h"
 #include "hostname-util.h"
 #include "id128-util.h"
+#include "mkdir.h"
 #include "mount-util.h"
 #include "mountpoint-util.h"
+#include "namespace-util.h"
 #include "nulstr-util.h"
 #include "os-util.h"
 #include "path-util.h"
@@ -1940,9 +1942,84 @@ const char* mount_options_from_part(const MountOptions *options, unsigned int pa
         LIST_FOREACH(mount_options, m, (MountOptions *)options)
                 if (partition_number == m->partition_number && !isempty(m->options))
                         return m->options;
+
         return NULL;
 }
 
+int mount_image_privately_interactively(
+                const char *image,
+                DissectImageFlags flags,
+                char **ret_directory,
+                LoopDevice **ret_loop_device,
+                DecryptedImage **ret_decrypted_image) {
+
+        _cleanup_(loop_device_unrefp) LoopDevice *d = NULL;
+        _cleanup_(decrypted_image_unrefp) DecryptedImage *decrypted_image = NULL;
+        _cleanup_(dissected_image_unrefp) DissectedImage *dissected_image = NULL;
+        _cleanup_(rmdir_and_freep) char *created_dir = NULL;
+        _cleanup_free_ char *temp = NULL;
+        int r;
+
+        /* Mounts an OS image at a temporary place, inside a newly created mount namespace of our own. This
+         * is used by tools such as systemd-tmpfiles or systemd-firstboot to operate on some disk image
+         * easily. */
+
+        assert(image);
+        assert(ret_directory);
+        assert(ret_loop_device);
+        assert(ret_decrypted_image);
+
+        r = tempfn_random_child(NULL, program_invocation_short_name, &temp);
+        if (r < 0)
+                return log_error_errno(r, "Failed to generate temporary mount directory: %m");
+
+        r = loop_device_make_by_path(
+                        image,
+                        FLAGS_SET(flags, DISSECT_IMAGE_READ_ONLY) ? O_RDONLY : O_RDWR,
+                        FLAGS_SET(flags, DISSECT_IMAGE_NO_PARTITION_TABLE) ? 0 : LO_FLAGS_PARTSCAN,
+                        &d);
+        if (r < 0)
+                return log_error_errno(r, "Failed to set up loopback device: %m");
+
+        r = dissect_image_and_warn(d->fd, image, NULL, 0, NULL, NULL, flags, &dissected_image);
+        if (r < 0)
+                return r;
+
+        r = dissected_image_decrypt_interactively(dissected_image, NULL, NULL, 0, NULL, NULL, NULL, 0, flags, &decrypted_image);
+        if (r < 0)
+                return r;
+
+        r = detach_mount_namespace();
+        if (r < 0)
+                return log_error_errno(r, "Failed to detach mount namespace: %m");
+
+        r = mkdir_p(temp, 0700);
+        if (r < 0)
+                return log_error_errno(r, "Failed to create mount point: %m");
+
+        created_dir = TAKE_PTR(temp);
+
+        r = dissected_image_mount(dissected_image, created_dir, UID_INVALID, flags);
+        if (r == -EUCLEAN)
+                return log_error_errno(r, "File system check on image failed: %m");
+        if (r < 0)
+                return log_error_errno(r, "Failed to mount image: %m");
+
+        if (decrypted_image) {
+                r = decrypted_image_relinquish(decrypted_image);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to relinquish DM devices: %m");
+        }
+
+        loop_device_relinquish(d);
+
+        *ret_directory = TAKE_PTR(created_dir);
+        *ret_loop_device = TAKE_PTR(d);
+        *ret_decrypted_image = TAKE_PTR(decrypted_image);
+
+        return 0;
+}
+
 static const char *const partition_designator_table[] = {
         [PARTITION_ROOT] = "root",
         [PARTITION_ROOT_SECONDARY] = "root-secondary",

src/shared/dissect-image.h

@@ -6,6 +6,7 @@
 #include "sd-id128.h"
 
 #include "list.h"
+#include "loop-util.h"
 #include "macro.h"
 
 typedef struct DissectedImage DissectedImage;
@@ -117,3 +118,5 @@ int partition_designator_from_string(const char *name) _pure_;
 int verity_metadata_load(const char *image, const char *root_hash_path, void **ret_roothash, size_t *ret_roothash_size, char **ret_verity_data, char **ret_roothashsig);
 bool dissected_image_can_do_verity(const DissectedImage *image, unsigned partition_designator);
 bool dissected_image_has_verity(const DissectedImage *image, unsigned partition_designator);
+
+int mount_image_privately_interactively(const char *path, DissectImageFlags flags, char **ret_directory, LoopDevice **ret_loop_device, DecryptedImage **ret_decrypted_image);

src/shared/logs-show.c

@@ -168,8 +168,12 @@ typedef struct ParseFieldVec {
         size_t *target_len;
 } ParseFieldVec;
 
-#define PARSE_FIELD_VEC_ENTRY(_field, _target, _target_len) \
-        { .field = _field, .field_len = strlen(_field), .target = _target, .target_len = _target_len }
+#define PARSE_FIELD_VEC_ENTRY(_field, _target, _target_len) {           \
+                .field = _field,                                        \
+                .field_len = strlen(_field),                            \
+                .target = _target,                                      \
+                .target_len = _target_len                               \
+        }
 
 static int parse_fieldv(const void *data, size_t length, const ParseFieldVec *fields, unsigned n_fields) {
         unsigned i;
@@ -1122,19 +1126,17 @@ static int output_cat_field(
                 FILE *f,
                 sd_journal *j,
                 OutputFlags flags,
+                int prio,
                 const char *field,
                 const size_t highlight[2]) {
 
-        const char *highlight_on, *highlight_off;
+        const char *color_on = "", *color_off = "", *highlight_on = "";
         const void *data;
         size_t l, fl;
         int r;
 
-        if (FLAGS_SET(flags, OUTPUT_COLOR)) {
-                highlight_on = ANSI_HIGHLIGHT_RED;
-                highlight_off = ANSI_NORMAL;
-        } else
-                highlight_on = highlight_off = "";
+        if (FLAGS_SET(flags, OUTPUT_COLOR))
+                get_log_colors(prio, &color_on, &color_off, &highlight_on);
 
         r = sd_journal_get_data(j, field, &data, &l);
         if (r == -EBADMSG) {
@@ -1153,15 +1155,23 @@ static int output_cat_field(
         data = (const uint8_t*) data + fl + 1;
         l -= fl + 1;
 
-        if (highlight && FLAGS_SET(flags, OUTPUT_COLOR)) {
-                assert(highlight[0] <= highlight[1]);
-                assert(highlight[1] <= l);
+        if (FLAGS_SET(flags, OUTPUT_COLOR)) {
+                if (highlight) {
+                        assert(highlight[0] <= highlight[1]);
+                        assert(highlight[1] <= l);
 
-                fwrite((const char*) data, 1, highlight[0], f);
-                fwrite(highlight_on, 1, strlen(highlight_on), f);
-                fwrite((const char*) data + highlight[0], 1, highlight[1] - highlight[0], f);
-                fwrite(highlight_off, 1, strlen(highlight_off), f);
-                fwrite((const char*) data + highlight[1], 1, l - highlight[1], f);
+                        fputs(color_on, f);
+                        fwrite((const char*) data, 1, highlight[0], f);
+                        fputs(highlight_on, f);
+                        fwrite((const char*) data + highlight[0], 1, highlight[1] - highlight[0], f);
+                        fputs(color_on, f);
+                        fwrite((const char*) data + highlight[1], 1, l - highlight[1], f);
+                        fputs(color_off, f);
+                } else {
+                        fputs(color_on, f);
+                        fwrite((const char*) data, 1, l, f);
+                        fputs(color_off, f);
+                }
         } else
                 fwrite((const char*) data, 1, l, f);
 
@@ -1178,20 +1188,44 @@ static int output_cat(
                 const Set *output_fields,
                 const size_t highlight[2]) {
 
+        int r, prio = LOG_INFO;
         const char *field;
         Iterator iterator;
-        int r;
 
         assert(j);
         assert(f);
 
         (void) sd_journal_set_data_threshold(j, 0);
 
+        if (FLAGS_SET(flags, OUTPUT_COLOR)) {
+                const void *data;
+                size_t l;
+
+                /* Determine priority of this entry, so that we can color it nicely */
+
+                r = sd_journal_get_data(j, "PRIORITY", &data, &l);
+                if (r == -EBADMSG) {
+                        log_debug_errno(r, "Skipping message we can't read: %m");
+                        return 0;
+                }
+                if (r < 0) {
+                        if (r != -ENOENT)
+                                return log_error_errno(r, "Failed to get data: %m");
+
+                        /* An entry without PRIORITY */
+                } else if (l == 10 && memcmp(data, "PRIORITY=", 9) == 0) {
+                        char c = ((char*) data)[9];
+
+                        if (c >= '0' && c <= '7')
+                                prio = c - '0';
+                }
+        }
+
         if (set_isempty(output_fields))
-                return output_cat_field(f, j, flags, "MESSAGE", highlight);
+                return output_cat_field(f, j, flags, prio, "MESSAGE", highlight);
 
         SET_FOREACH(field, output_fields, iterator) {
-                r = output_cat_field(f, j, flags, field, streq(field, "MESSAGE") ? highlight : NULL);
+                r = output_cat_field(f, j, flags, prio, field, streq(field, "MESSAGE") ? highlight : NULL);
                 if (r < 0)
                         return r;
         }

src/sysusers/sysusers.c

@@ -7,17 +7,19 @@
 #include "conf-files.h"
 #include "copy.h"
 #include "def.h"
+#include "dissect-image.h"
 #include "fd-util.h"
 #include "fileio.h"
 #include "format-util.h"
 #include "fs-util.h"
 #include "hashmap.h"
 #include "main-func.h"
+#include "mount-util.h"
 #include "pager.h"
 #include "path-util.h"
 #include "pretty-print.h"
-#include "set.h"
 #include "selinux-util.h"
+#include "set.h"
 #include "smack-util.h"
 #include "specifier.h"
 #include "string-util.h"
@@ -63,6 +65,7 @@ typedef struct Item {
 } Item;
 
 static char *arg_root = NULL;
+static char *arg_image = NULL;
 static bool arg_cat_config = false;
 static const char *arg_replace = NULL;
 static bool arg_inline = false;
@@ -93,6 +96,7 @@ STATIC_DESTRUCTOR_REGISTER(database_by_groupname, hashmap_freep);
 STATIC_DESTRUCTOR_REGISTER(database_groups, set_free_freep);
 STATIC_DESTRUCTOR_REGISTER(uid_range, freep);
 STATIC_DESTRUCTOR_REGISTER(arg_root, freep);
+STATIC_DESTRUCTOR_REGISTER(arg_image, freep);
 
 static int errno_is_not_exists(int code) {
         /* See getpwnam(3) and getgrnam(3): those codes and others can be returned if the user or group are
@@ -1739,6 +1743,7 @@ static int help(void) {
                "     --version              Show package version\n"
                "     --cat-config           Show configuration files\n"
                "     --root=PATH            Operate on an alternate filesystem root\n"
+               "     --image=PATH           Operate on disk image as filesystem root\n"
                "     --replace=PATH         Treat arguments as replacement for PATH\n"
                "     --inline               Treat arguments as configuration lines\n"
                "     --no-pager             Do not pipe output into a pager\n"
@@ -1756,6 +1761,7 @@ static int parse_argv(int argc, char *argv[]) {
                 ARG_VERSION = 0x100,
                 ARG_CAT_CONFIG,
                 ARG_ROOT,
+                ARG_IMAGE,
                 ARG_REPLACE,
                 ARG_INLINE,
                 ARG_NO_PAGER,
@@ -1766,6 +1772,7 @@ static int parse_argv(int argc, char *argv[]) {
                 { "version",    no_argument,       NULL, ARG_VERSION    },
                 { "cat-config", no_argument,       NULL, ARG_CAT_CONFIG },
                 { "root",       required_argument, NULL, ARG_ROOT       },
+                { "image",      required_argument, NULL, ARG_IMAGE          },
                 { "replace",    required_argument, NULL, ARG_REPLACE    },
                 { "inline",     no_argument,       NULL, ARG_INLINE     },
                 { "no-pager",   no_argument,       NULL, ARG_NO_PAGER   },
@@ -1797,6 +1804,12 @@ static int parse_argv(int argc, char *argv[]) {
                                 return r;
                         break;
 
+                case ARG_IMAGE:
+                        r = parse_path_argument_and_warn(optarg, /* suppress_root= */ false, &arg_image);
+                        if (r < 0)
+                                return r;
+                        break;
+
                 case ARG_REPLACE:
                         if (!path_is_absolute(optarg) ||
                             !endswith(optarg, ".conf"))
@@ -1829,6 +1842,9 @@ static int parse_argv(int argc, char *argv[]) {
                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
                                        "When --replace= is given, some configuration items must be specified");
 
+        if (arg_image && arg_root)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Please specify either --root= or --image=, the combination of both is not supported.");
+
         return 1;
 }
 
@@ -1880,6 +1896,9 @@ static int read_config_files(char **args) {
 }
 
 static int run(int argc, char *argv[]) {
+        _cleanup_(loop_device_unrefp) LoopDevice *loop_device = NULL;
+        _cleanup_(decrypted_image_unrefp) DecryptedImage *decrypted_image = NULL;
+        _cleanup_(umount_and_rmdir_and_freep) char *unlink_dir = NULL;
         _cleanup_close_ int lock = -1;
         Iterator iterator;
         Item *i;
@@ -1900,6 +1919,23 @@ static int run(int argc, char *argv[]) {
         if (r < 0)
                 return r;
 
+        if (arg_image) {
+                assert(!arg_root);
+
+                r = mount_image_privately_interactively(
+                                arg_image,
+                                DISSECT_IMAGE_REQUIRE_ROOT|DISSECT_IMAGE_VALIDATE_OS|DISSECT_IMAGE_RELAX_VAR_CHECK|DISSECT_IMAGE_FSCK,
+                                &unlink_dir,
+                                &loop_device,
+                                &decrypted_image);
+                if (r < 0)
+                        return r;
+
+                arg_root = strdup(unlink_dir);
+                if (!arg_root)
+                        return log_oom();
+        }
+
         /* If command line arguments are specified along with --replace, read all
          * configuration files and insert the positional arguments at the specified
          * place. Otherwise, if command line arguments are specified, execute just

src/tmpfiles/tmpfiles.c

@@ -26,6 +26,7 @@
 #include "copy.h"
 #include "def.h"
 #include "dirent-util.h"
+#include "dissect-image.h"
 #include "escape.h"
 #include "fd-util.h"
 #include "fileio.h"
@@ -38,6 +39,7 @@
 #include "macro.h"
 #include "main-func.h"
 #include "mkdir.h"
+#include "mount-util.h"
 #include "mountpoint-util.h"
 #include "offline-passwd.h"
 #include "pager.h"
@@ -164,6 +166,7 @@ static PagerFlags arg_pager_flags = 0;
 static char **arg_include_prefixes = NULL;
 static char **arg_exclude_prefixes = NULL;
 static char *arg_root = NULL;
+static char *arg_image = NULL;
 static char *arg_replace = NULL;
 
 #define MAX_DEPTH 256
@@ -177,6 +180,7 @@ STATIC_DESTRUCTOR_REGISTER(unix_sockets, set_free_freep);
 STATIC_DESTRUCTOR_REGISTER(arg_include_prefixes, freep);
 STATIC_DESTRUCTOR_REGISTER(arg_exclude_prefixes, freep);
 STATIC_DESTRUCTOR_REGISTER(arg_root, freep);
+STATIC_DESTRUCTOR_REGISTER(arg_image, freep);
 
 static int specifier_machine_id_safe(char specifier, const void *data, const void *userdata, char **ret);
 static int specifier_directory(char specifier, const void *data, const void *userdata, char **ret);
@@ -2884,6 +2888,27 @@ static int cat_config(char **config_dirs, char **args) {
         return cat_files(NULL, files, 0);
 }
 
+static int exclude_default_prefixes(void) {
+        int r;
+
+        /* Provide an easy way to exclude virtual/memory file systems from what we do here. Useful in
+         * combination with --root= where we probably don't want to apply stuff to these dirs as they are
+         * likely over-mounted if the root directory is actually used, and it wouldbe less than ideal to have
+         * all kinds of files created/adjusted underneath these mount points. */
+
+        r = strv_extend_strv(
+                        &arg_exclude_prefixes,
+                        STRV_MAKE("/dev",
+                                  "/proc",
+                                  "/run",
+                                  "/sys"),
+                                 true);
+        if (r < 0)
+                return log_oom();
+
+        return 0;
+}
+
 static int help(void) {
         _cleanup_free_ char *link = NULL;
         int r;
@@ -2904,7 +2929,9 @@ static int help(void) {
                "     --boot                 Execute actions only safe at boot\n"
                "     --prefix=PATH          Only apply rules with the specified prefix\n"
                "     --exclude-prefix=PATH  Ignore rules with the specified prefix\n"
+               "  -E                        Ignore rules prefixed with /dev, /proc, /run, /sys\n"
                "     --root=PATH            Operate on an alternate filesystem root\n"
+               "     --image=PATH           Operate on disk image as filesystem root\n"
                "     --replace=PATH         Treat arguments as replacement for PATH\n"
                "     --no-pager             Do not pipe output into a pager\n"
                "\nSee the %s for details.\n"
@@ -2928,6 +2955,7 @@ static int parse_argv(int argc, char *argv[]) {
                 ARG_PREFIX,
                 ARG_EXCLUDE_PREFIX,
                 ARG_ROOT,
+                ARG_IMAGE,
                 ARG_REPLACE,
                 ARG_NO_PAGER,
         };
@@ -2944,6 +2972,7 @@ static int parse_argv(int argc, char *argv[]) {
                 { "prefix",         required_argument,   NULL, ARG_PREFIX         },
                 { "exclude-prefix", required_argument,   NULL, ARG_EXCLUDE_PREFIX },
                 { "root",           required_argument,   NULL, ARG_ROOT           },
+                { "image",          required_argument,   NULL, ARG_IMAGE          },
                 { "replace",        required_argument,   NULL, ARG_REPLACE        },
                 { "no-pager",       no_argument,         NULL, ARG_NO_PAGER       },
                 {}
@@ -2954,7 +2983,7 @@ static int parse_argv(int argc, char *argv[]) {
         assert(argc >= 0);
         assert(argv);
 
-        while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0)
+        while ((c = getopt_long(argc, argv, "hE", options, NULL)) >= 0)
 
                 switch (c) {
 
@@ -3004,6 +3033,21 @@ static int parse_argv(int argc, char *argv[]) {
                                 return r;
                         break;
 
+                case ARG_IMAGE:
+                        r = parse_path_argument_and_warn(optarg, /* suppress_root= */ false, &arg_image);
+                        if (r < 0)
+                                return r;
+
+                        /* Imply -E here since it makes little sense to create files persistently in the /run mointpoint of a disk image */
+                        _fallthrough_;
+
+                case 'E':
+                        r = exclude_default_prefixes();
+                        if (r < 0)
+                                return r;
+
+                        break;
+
                 case ARG_REPLACE:
                         if (!path_is_absolute(optarg) ||
                             !endswith(optarg, ".conf"))
@@ -3036,6 +3080,13 @@ static int parse_argv(int argc, char *argv[]) {
                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
                                        "When --replace= is given, some configuration items must be specified");
 
+        if (arg_root && arg_user)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "Combination of --user and --root= is not supported.");
+
+        if (arg_image && arg_root)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Please specify either --root= or --image=, the combination of both is not supported.");
+
         return 1;
 }
 
@@ -3211,6 +3262,9 @@ DEFINE_PRIVATE_HASH_OPS_WITH_VALUE_DESTRUCTOR(item_array_hash_ops, char, string_
                                               ItemArray, item_array_free);
 
 static int run(int argc, char *argv[]) {
+        _cleanup_(loop_device_unrefp) LoopDevice *loop_device = NULL;
+        _cleanup_(decrypted_image_unrefp) DecryptedImage *decrypted_image = NULL;
+        _cleanup_(umount_and_rmdir_and_freep) char *unlink_dir = NULL;
         _cleanup_strv_free_ char **config_dirs = NULL;
         bool invalid_config = false;
         Iterator iterator;
@@ -3243,10 +3297,20 @@ static int run(int argc, char *argv[]) {
 
         if (DEBUG_LOGGING) {
                 _cleanup_free_ char *t = NULL;
+                char **i;
 
-                t = strv_join(config_dirs, "\n\t");
-                if (t)
-                        log_debug("Looking for configuration files in (higher priority first):\n\t%s", t);
+                STRV_FOREACH(i, config_dirs) {
+                        _cleanup_free_ char *j = NULL;
+
+                        j = path_join(arg_root, *i);
+                        if (!j)
+                                return log_oom();
+
+                        if (!strextend(&t, "\n\t", j, NULL))
+                                return log_oom();
+                }
+
+                log_debug("Looking for configuration files in (higher priority first):%s", t);
         }
 
         if (arg_cat_config) {
@@ -3261,6 +3325,23 @@ static int run(int argc, char *argv[]) {
         if (r < 0)
                 return r;
 
+        if (arg_image) {
+                assert(!arg_root);
+
+                r = mount_image_privately_interactively(
+                                arg_image,
+                                DISSECT_IMAGE_REQUIRE_ROOT|DISSECT_IMAGE_VALIDATE_OS|DISSECT_IMAGE_RELAX_VAR_CHECK|DISSECT_IMAGE_FSCK,
+                                &unlink_dir,
+                                &loop_device,
+                                &decrypted_image);
+                if (r < 0)
+                        return r;
+
+                arg_root = strdup(unlink_dir);
+                if (!arg_root)
+                        return log_oom();
+        }
+
         items = ordered_hashmap_new(&item_array_hash_ops);
         globs = ordered_hashmap_new(&item_array_hash_ops);
         if (!items || !globs)

units/systemd-user-sessions.service.in

@@ -10,7 +10,7 @@
 [Unit]
 Description=Permit User Sessions
 Documentation=man:systemd-user-sessions.service(8)
-After=remote-fs.target nss-user-lookup.target network.target
+After=remote-fs.target nss-user-lookup.target network.target home.mount
 
 [Service]
 Type=oneshot