Merge pull request #25302 from poettering/dissect-with

dissect: add new --with command for excuting commands with a DDI mounted

man/systemd-dissect.xml

@@ -34,6 +34,9 @@
     <cmdsynopsis>
       <command>systemd-dissect <arg choice="opt" rep="repeat">OPTIONS</arg> <option>--list</option> <arg choice="plain"><replaceable>IMAGE</replaceable></arg></command>
     </cmdsynopsis>
+    <cmdsynopsis>
+      <command>systemd-dissect <arg choice="opt" rep="repeat">OPTIONS</arg> <option>--with</option> <arg choice="plain"><replaceable>IMAGE</replaceable></arg> <arg choice="opt" rep="repeat"><replaceable>COMMAND</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>
@@ -160,6 +163,19 @@
         standard output.</para></listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term><option>--with</option></term>
+
+        <listitem><para>Runs the specified command with the specified OS image mounted. This will mount the
+        image to a temporary directory, switch the current working directory to it, and invoke the specified
+        command line as child process. Once the process ends it will unmount the image again, and remove the
+        temporary directory. If no command is specified a shell is invoked. The image is mounted writable,
+        use <option>--read-only</option> to switch to read-only operation. The invoked process will have the
+        <varname>$SYSTEMD_DISSECT_ROOT</varname> environment variable set, containing the absolute path name
+        of the temporary mount point, i.e. the same directory that is set as the current working
+        directory.</para></listitem>
+      </varlistentry>
+
       <varlistentry>
         <term><option>--copy-from</option></term>
         <term><option>-x</option></term>
@@ -294,14 +310,24 @@
       <xi:include href="standard-options.xml" xpointer="no-legend" />
       <xi:include href="standard-options.xml" xpointer="json" />
     </variablelist>
-
   </refsect1>
 
   <refsect1>
     <title>Exit status</title>
 
-    <para>On success, 0 is returned, a non-zero failure code
-    otherwise.</para>
+    <para>On success, 0 is returned, a non-zero failure code otherwise. If the <option>--with</option>
+    command is used the exit status of the invoked command is propagated.</para>
+  </refsect1>
+
+
+  <refsect1>
+    <title>Examples</title>
+
+    <example>
+      <title>Generate a tarball from an OS disk image</title>
+
+      <programlisting>$ systemd-dissect --with foo.raw tar cz . > foo.tar.gz</programlisting>
+    </example>
   </refsect1>
 
   <refsect1>

src/dissect/dissect.c

@@ -36,6 +36,7 @@
 #include "parse-util.h"
 #include "path-util.h"
 #include "pretty-print.h"
+#include "process-util.h"
 #include "recurse-dir.h"
 #include "stat-util.h"
 #include "string-util.h"
@@ -49,6 +50,7 @@ static enum {
         ACTION_MOUNT,
         ACTION_UMOUNT,
         ACTION_LIST,
+        ACTION_WITH,
         ACTION_COPY_FROM,
         ACTION_COPY_TO,
 } arg_action = ACTION_DISSECT;
@@ -68,8 +70,10 @@ 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 char **arg_argv = NULL;
 
 STATIC_DESTRUCTOR_REGISTER(arg_verity_settings, verity_settings_done);
+STATIC_DESTRUCTOR_REGISTER(arg_argv, strv_freep);
 
 static int help(void) {
         _cleanup_free_ char *link = NULL;
@@ -83,6 +87,7 @@ static int help(void) {
                "%1$s [OPTIONS...] --mount IMAGE PATH\n"
                "%1$s [OPTIONS...] --umount PATH\n"
                "%1$s [OPTIONS...] --list IMAGE\n"
+               "%1$s [OPTIONS...] --with IMAGE [COMMAND…]\n"
                "%1$s [OPTIONS...] --copy-from IMAGE PATH [TARGET]\n"
                "%1$s [OPTIONS...] --copy-to IMAGE [SOURCE] PATH\n\n"
                "%5$sDissect a Discoverable Disk Image (DDI).%6$s\n\n"
@@ -113,6 +118,7 @@ static int help(void) {
                "  -U                      Shortcut for --umount --rmdir\n"
                "  -l --list               List all the files and directories of the specified\n"
                "                          OS image\n"
+               "     --with               Mount, run command, unmount\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",
@@ -126,12 +132,56 @@ static int help(void) {
         return 0;
 }
 
+static int patch_argv(int *argc, char ***argv, char ***buf) {
+        _cleanup_free_ char **l = NULL;
+        char **e;
+
+        assert(argc);
+        assert(*argc >= 0);
+        assert(argv);
+        assert(*argv);
+        assert(buf);
+
+        /* Ugly hack: if --with is included in command line, also insert "--" immediately after it, to make
+         * getopt_long() stop processing switches */
+
+        for (e = *argv + 1; e < *argv + *argc; e++) {
+                assert(*e);
+
+                if (streq(*e, "--with"))
+                        break;
+        }
+
+        if (e >= *argv + *argc || streq_ptr(e[1], "--")) {
+                /* No --with used? Or already followed by "--"? Then don't do anything */
+                *buf = NULL;
+                return 0;
+        }
+
+        /* Insert the extra "--" right after the --with */
+        l = new(char*, *argc + 2);
+        if (!l)
+                return log_oom();
+
+        size_t idx = e - *argv + 1;
+        memcpy(l, *argv, sizeof(char*) * idx);                          /* copy everything up to and including the --with */
+        l[idx] = (char*) "--";                                          /* insert "--" */
+        memcpy(l + idx + 1, e + 1, sizeof(char*) * (*argc - idx + 1));  /* copy the rest, including trailing NULL entry */
+
+        (*argc)++;
+        (*argv) = l;
+
+        *buf = TAKE_PTR(l);
+        return 1;
+}
+
 static int parse_argv(int argc, char *argv[]) {
 
         enum {
                 ARG_VERSION = 0x100,
                 ARG_NO_PAGER,
                 ARG_NO_LEGEND,
+                ARG_WITH,
                 ARG_DISCARD,
                 ARG_FSCK,
                 ARG_GROWFS,
@@ -150,6 +200,7 @@ static int parse_argv(int argc, char *argv[]) {
                 { "no-legend",     no_argument,       NULL, ARG_NO_LEGEND     },
                 { "mount",         no_argument,       NULL, 'm'               },
                 { "umount",        no_argument,       NULL, 'u'               },
+                { "with",          no_argument,       NULL, ARG_WITH          },
                 { "read-only",     no_argument,       NULL, 'r'               },
                 { "discard",       required_argument, NULL, ARG_DISCARD       },
                 { "fsck",          required_argument, NULL, ARG_FSCK          },
@@ -166,11 +217,16 @@ static int parse_argv(int argc, char *argv[]) {
                 {}
         };
 
+        _cleanup_free_ char **buf = NULL; /* we use free(), not strv_free() here, as we don't copy the strings here */
         int c, r;
 
         assert(argc >= 0);
         assert(argv);
 
+        r = patch_argv(&argc, &argv, &buf);
+        if (r < 0)
+                return r;
+
         while ((c = getopt_long(argc, argv, "hmurMUlxa", options, NULL)) >= 0) {
 
                 switch (c) {
@@ -222,6 +278,10 @@ static int parse_argv(int argc, char *argv[]) {
                         arg_flags |= DISSECT_IMAGE_READ_ONLY;
                         break;
 
+                case ARG_WITH:
+                        arg_action = ACTION_WITH;
+                        break;
+
                 case 'x':
                         arg_action = ACTION_COPY_FROM;
                         arg_flags |= DISSECT_IMAGE_READ_ONLY;
@@ -332,7 +392,6 @@ static int parse_argv(int argc, char *argv[]) {
                 default:
                         assert_not_reached();
                 }
-
         }
 
         switch (arg_action) {
@@ -403,6 +462,20 @@ static int parse_argv(int argc, char *argv[]) {
                 arg_flags |= DISSECT_IMAGE_REQUIRE_ROOT;
                 break;
 
+        case ACTION_WITH:
+                if (optind >= argc)
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                               "Expected an image file path and an optional command line.");
+
+                arg_image = argv[optind];
+                if (argc > optind + 1) {
+                        arg_argv = strv_copy(argv + optind + 1);
+                        if (!arg_argv)
+                                return log_oom();
+                }
+
+                break;
+
         default:
                 assert_not_reached();
         }
@@ -518,6 +591,8 @@ static int action_dissect(DissectedImage *m, LoopDevice *d) {
                                "Mach. Info:");
                 strv_pair_print(m->os_release,
                                "OS Release:");
+                strv_pair_print(m->initrd_release,
+                                "initrd R.:");
                 strv_pair_print(m->extension_release,
                                " Ext. Rel.:");
 
@@ -525,6 +600,7 @@ static int action_dissect(DissectedImage *m, LoopDevice *d) {
                     !sd_id128_is_null(m->machine_id) ||
                     !strv_isempty(m->machine_info) ||
                     !strv_isempty(m->os_release) ||
+                    !strv_isempty(m->initrd_release) ||
                     !strv_isempty(m->extension_release))
                         putc('\n', stdout);
 
@@ -535,6 +611,8 @@ static int action_dissect(DissectedImage *m, LoopDevice *d) {
 
                 printf("            %s portable service\n",
                        COLOR_MARK_BOOL(strv_env_pairs_get(m->os_release, "PORTABLE_PREFIXES")));
+                printf("            %s initrd\n",
+                       COLOR_MARK_BOOL(!strv_isempty(m->initrd_release)));
 
                 r = get_sysext_scopes(m, &sysext_scopes);
                 if (r < 0)
@@ -549,7 +627,7 @@ static int action_dissect(DissectedImage *m, LoopDevice *d) {
 
                 putc('\n', stdout);
         } else {
-                _cleanup_(json_variant_unrefp) JsonVariant *mi = NULL, *osr = NULL, *exr = NULL;
+                _cleanup_(json_variant_unrefp) JsonVariant *mi = NULL, *osr = NULL, *irdr = NULL, *exr = NULL;
                 _cleanup_strv_free_ char **sysext_scopes = NULL;
 
                 if (!strv_isempty(m->machine_info)) {
@@ -564,6 +642,12 @@ static int action_dissect(DissectedImage *m, LoopDevice *d) {
                                 return log_oom();
                 }
 
+                if (!strv_isempty(m->initrd_release)) {
+                        r = strv_pair_to_json(m->initrd_release, &irdr);
+                        if (r < 0)
+                                return log_oom();
+                }
+
                 if (!strv_isempty(m->extension_release)) {
                         r = strv_pair_to_json(m->extension_release, &exr);
                         if (r < 0)
@@ -581,9 +665,11 @@ static int action_dissect(DissectedImage *m, LoopDevice *d) {
                                                JSON_BUILD_PAIR_CONDITION(!sd_id128_is_null(m->machine_id), "machineId", JSON_BUILD_ID128(m->machine_id)),
                                                JSON_BUILD_PAIR_CONDITION(mi, "machineInfo", JSON_BUILD_VARIANT(mi)),
                                                JSON_BUILD_PAIR_CONDITION(osr, "osRelease", JSON_BUILD_VARIANT(osr)),
+                                               JSON_BUILD_PAIR_CONDITION(osr, "initrdRelease", JSON_BUILD_VARIANT(irdr)),
                                                JSON_BUILD_PAIR_CONDITION(exr, "extensionRelease", JSON_BUILD_VARIANT(exr)),
                                                JSON_BUILD_PAIR("useBootableUefi", JSON_BUILD_BOOLEAN(m->partitions[PARTITION_ESP].found)),
                                                JSON_BUILD_PAIR_CONDITION(m->has_init_system >= 0, "useBootableContainer", JSON_BUILD_BOOLEAN(m->has_init_system)),
+                                               JSON_BUILD_PAIR("useInitrd", JSON_BUILD_BOOLEAN(!strv_isempty(m->initrd_release))),
                                                JSON_BUILD_PAIR("usePortableService", JSON_BUILD_BOOLEAN(strv_env_pairs_get(m->os_release, "PORTABLE_MATCHES"))),
                                                JSON_BUILD_PAIR("useSystemExtension", JSON_BUILD_BOOLEAN(strv_contains(sysext_scopes, "system"))),
                                                JSON_BUILD_PAIR("useInitRDExtension", JSON_BUILD_BOOLEAN(strv_contains(sysext_scopes, "initrd"))),
@@ -958,6 +1044,97 @@ static int action_umount(const char *path) {
         return 0;
 }
 
+static int action_with(DissectedImage *m, LoopDevice *d) {
+        _cleanup_(umount_and_rmdir_and_freep) char *mounted_dir = NULL;
+        _cleanup_(rmdir_and_freep) char *created_dir = NULL;
+        _cleanup_free_ char *temp = NULL;
+        int r, rcode;
+
+        r = dissected_image_decrypt_interactively(
+                        m, NULL,
+                        &arg_verity_settings,
+                        arg_flags);
+        if (r < 0)
+                return r;
+
+        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 = 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_and_warn(m, created_dir, UID_INVALID, UID_INVALID, arg_flags);
+        if (r < 0)
+                return r;
+
+        mounted_dir = TAKE_PTR(created_dir);
+
+        r = dissected_image_relinquish(m);
+        if (r < 0)
+                return log_error_errno(r, "Failed to relinquish DM and loopback block devices: %m");
+
+        r = loop_device_flock(d, LOCK_UN);
+        if (r < 0)
+                return log_error_errno(r, "Failed to unlock loopback block device: %m");
+
+        rcode = safe_fork("(with)", FORK_CLOSE_ALL_FDS|FORK_LOG|FORK_WAIT, NULL);
+        if (rcode == 0) {
+                /* Child */
+
+                if (chdir(mounted_dir) < 0) {
+                        log_error_errno(errno, "Failed to change to '%s' directory: %m", mounted_dir);
+                        _exit(EXIT_FAILURE);
+                }
+
+                if (setenv("SYSTEMD_DISSECT_ROOT", mounted_dir, /* overwrite= */ true) < 0) {
+                        log_error_errno(errno, "Failed to set $SYSTEMD_DISSECT_ROOT: %m");
+                        _exit(EXIT_FAILURE);
+                }
+
+                if (strv_isempty(arg_argv)) {
+                        const char *sh;
+
+                        sh = secure_getenv("SHELL");
+                        if (sh) {
+                                execvp(sh, STRV_MAKE(sh));
+                                log_warning_errno(errno, "Failed to execute $SHELL, falling back to /bin/sh: %m");
+                        }
+
+                        execl("/bin/sh", "sh", NULL);
+                        log_error_errno(errno, "Failed to invoke /bin/sh: %m");
+                } else {
+                        execvp(arg_argv[0], arg_argv);
+                        log_error_errno(errno, "Failed to execute '%s': %m", arg_argv[0]);
+                }
+
+                _exit(EXIT_FAILURE);
+        }
+
+        /* Let's manually detach everything, to make things synchronous */
+        r = loop_device_flock(d, LOCK_SH);
+        if (r < 0)
+                log_warning_errno(r, "Failed to lock loopback block device, ignoring: %m");
+
+        r = umount_recursive(mounted_dir, 0);
+        if (r < 0)
+                log_warning_errno(r, "Failed to unmount '%s', ignoring: %m", mounted_dir);
+        else
+                loop_device_unrelinquish(d); /* Let's try to destroy the loopback device */
+
+        created_dir = TAKE_PTR(mounted_dir);
+
+        if (rmdir(created_dir) < 0)
+                log_warning_errno(r, "Failed to remove directory '%s', ignoring: %m", created_dir);
+
+        temp = TAKE_PTR(created_dir);
+
+        return rcode;
+}
+
 static int run(int argc, char *argv[]) {
         _cleanup_(dissected_image_unrefp) DissectedImage *m = NULL;
         _cleanup_(loop_device_unrefp) LoopDevice *d = NULL;
@@ -1026,6 +1203,10 @@ static int run(int argc, char *argv[]) {
                 r = action_list_or_copy(m, d);
                 break;
 
+        case ACTION_WITH:
+                r = action_with(m, d);
+                break;
+
         default:
                 assert_not_reached();
         }

src/shared/dissect-image.c

@@ -1296,6 +1296,7 @@ DissectedImage* dissected_image_unref(DissectedImage *m) {
         free(m->hostname);
         strv_free(m->machine_info);
         strv_free(m->os_release);
+        strv_free(m->initrd_release);
         strv_free(m->extension_release);
 
         return mfree(m);
@@ -2771,6 +2772,7 @@ int dissected_image_acquire_metadata(DissectedImage *m, DissectImageFlags extra_
                 META_MACHINE_ID,
                 META_MACHINE_INFO,
                 META_OS_RELEASE,
+                META_INITRD_RELEASE,
                 META_EXTENSION_RELEASE,
                 META_HAS_INIT_SYSTEM,
                 _META_MAX,
@@ -2782,11 +2784,13 @@ int dissected_image_acquire_metadata(DissectedImage *m, DissectImageFlags extra_
                 [META_MACHINE_INFO]      = "/etc/machine-info\0",
                 [META_OS_RELEASE]        = ("/etc/os-release\0"
                                             "/usr/lib/os-release\0"),
+                [META_INITRD_RELEASE]    = ("/etc/initrd-release\0"
+                                            "/usr/lib/initrd-release\0"),
                 [META_EXTENSION_RELEASE] = "extension-release\0",    /* Used only for logging. */
                 [META_HAS_INIT_SYSTEM]   = "has-init-system\0",      /* ditto */
         };
 
-        _cleanup_strv_free_ char **machine_info = NULL, **os_release = NULL, **extension_release = NULL;
+        _cleanup_strv_free_ char **machine_info = NULL, **os_release = NULL, **initrd_release = NULL, **extension_release = NULL;
         _cleanup_close_pair_ int error_pipe[2] = { -1, -1 };
         _cleanup_(rmdir_and_freep) char *t = NULL;
         _cleanup_(sigkill_waitp) pid_t child = 0;
@@ -2982,6 +2986,13 @@ int dissected_image_acquire_metadata(DissectedImage *m, DissectImageFlags extra_
 
                         break;
 
+                case META_INITRD_RELEASE:
+                        r = load_env_file_pairs(f, "initrd-release", &initrd_release);
+                        if (r < 0)
+                                log_debug_errno(r, "Failed to read initrd release file of image: %m");
+
+                        break;
+
                 case META_EXTENSION_RELEASE:
                         r = load_env_file_pairs(f, "extension-release", &extension_release);
                         if (r < 0)
@@ -3024,6 +3035,7 @@ int dissected_image_acquire_metadata(DissectedImage *m, DissectImageFlags extra_
         m->machine_id = machine_id;
         strv_free_and_replace(m->machine_info, machine_info);
         strv_free_and_replace(m->os_release, os_release);
+        strv_free_and_replace(m->initrd_release, initrd_release);
         strv_free_and_replace(m->extension_release, extension_release);
         m->has_init_system = has_init_system;
 

src/shared/dissect-image.h

@@ -233,6 +233,7 @@ struct DissectedImage {
         sd_id128_t machine_id;
         char **machine_info;
         char **os_release;
+        char **initrd_release;
         char **extension_release;
         int has_init_system;
 };

test/TEST-50-DISSECT/test.sh

@@ -12,7 +12,6 @@ TEST_INSTALL_VERITY_MINIMAL=1
 # shellcheck source=test/test-functions
 . "${TEST_BASE_DIR:?}/test-functions"
 
-
 command -v mksquashfs >/dev/null 2>&1 || exit 0
 command -v veritysetup >/dev/null 2>&1 || exit 0
 command -v sfdisk >/dev/null 2>&1 || exit 0
@@ -27,6 +26,7 @@ test_append_files() {
         install_dmevent
         generate_module_dependencies
         inst_binary wc
+        inst_binary sha256sum
         if command -v openssl >/dev/null 2>&1; then
             inst_binary openssl
         fi

test/units/testsuite-50.sh

@@ -41,6 +41,14 @@ systemd-dissect --json=short "${image}.raw" | grep -q -F '{"rw":"ro","designator
 systemd-dissect "${image}.raw" | grep -q -F "MARKER=1"
 systemd-dissect "${image}.raw" | grep -q -F -f <(sed 's/"//g' "$os_release")
 
+systemd-dissect --list "${image}.raw" | grep -q '^etc/os-release$'
+
+read -r SHA256SUM1 _ < <(systemd-dissect --copy-from "${image}.raw" etc/os-release | sha256sum)
+test "$SHA256SUM1" != ""
+read -r SHA256SUM2 _ < <(systemd-dissect --read-only --with "${image}.raw" sha256sum etc/os-release)
+test "$SHA256SUM2" != ""
+test "$SHA256SUM1" = "$SHA256SUM2"
+
 mv "${image}.verity" "${image}.fooverity"
 mv "${image}.roothash" "${image}.foohash"
 systemd-dissect --json=short "${image}.raw" --root-hash="${roothash}" --verity-data="${image}.fooverity" | grep -q -F '{"rw":"ro","designator":"root","partition_uuid":null,"partition_label":null,"fstype":"squashfs","architecture":null,"verity":"external"'