Merge pull request #14712 from wlhlm/root-storage-daemons-docs-fix

Tiny fix for example code in docs

TODO

@@ -38,8 +38,6 @@ Features:
 * by default, in systemd --user service bump the OOMAdjust to 100, as privs
   allow so that systemd survives
 
-* when dissecting images, warn about unrecognized partition flags
-
 * honour specifiers in unit files that resolve to some very basic
   /etc/os-release data, such as ID, VERSION_ID, BUILD_ID, VARIANT_ID.
 
@@ -172,10 +170,6 @@ Features:
   right) become genuine first class citizens, and we gain automatic, sane JSON
   output for them.
 
-* dissector: invoke fsck on the file systems we encounter, after all ext4 is
-  still pretty popular (and we mount the ESP too with it after all, which is
-  fat)
-
 * 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.
 

docs/ROOT_STORAGE_DAEMONS.md

@@ -87,11 +87,11 @@ systemd 38:
 Processes (run by the root user) whose first character of the zeroth command
 line argument is `@` are excluded from the killing spree, much the same way as
 kernel threads are excluded too. Thus, a daemon which wants to take advantage
-of this logic needs to place the following at the top of its main() function:
+of this logic needs to place the following at the top of its `main()` function:
 
 ```c
 ...
-[0][0] = '@';
+argv[0][0] = '@';
 ...
 ```
 

src/core/execute.c

@@ -2603,7 +2603,7 @@ static int apply_mount_namespace(
                             needs_sandboxing ? context->protect_home : PROTECT_HOME_NO,
                             needs_sandboxing ? context->protect_system : PROTECT_SYSTEM_NO,
                             context->mount_flags,
-                            DISSECT_IMAGE_DISCARD_ON_LOOP|DISSECT_IMAGE_RELAX_VAR_CHECK,
+                            DISSECT_IMAGE_DISCARD_ON_LOOP|DISSECT_IMAGE_RELAX_VAR_CHECK|DISSECT_IMAGE_FSCK,
                             error_path);
 
         /* If we couldn't set up the namespace this is probably due to a missing capability. setup_namespace() reports

src/dissect/dissect.c

@@ -11,6 +11,7 @@
 #include "log.h"
 #include "loop-util.h"
 #include "main-func.h"
+#include "parse-util.h"
 #include "string-util.h"
 #include "strv.h"
 #include "user-util.h"
@@ -22,7 +23,7 @@ static enum {
 } arg_action = ACTION_DISSECT;
 static const char *arg_image = NULL;
 static const char *arg_path = NULL;
-static DissectImageFlags arg_flags = DISSECT_IMAGE_REQUIRE_ROOT|DISSECT_IMAGE_DISCARD_ON_LOOP|DISSECT_IMAGE_RELAX_VAR_CHECK;
+static DissectImageFlags arg_flags = DISSECT_IMAGE_REQUIRE_ROOT|DISSECT_IMAGE_DISCARD_ON_LOOP|DISSECT_IMAGE_RELAX_VAR_CHECK|DISSECT_IMAGE_FSCK;
 static void *arg_root_hash = NULL;
 static size_t arg_root_hash_size = 0;
 
@@ -36,6 +37,7 @@ static void help(void) {
                "     --version         Show package version\n"
                "  -m --mount           Mount the image to the specified directory\n"
                "  -r --read-only       Mount read-only\n"
+               "     --fsck=BOOL       Run fsck before mounting\n"
                "     --discard=MODE    Choose 'discard' mode (disabled, loop, all, crypto)\n"
                "     --root-hash=HASH  Specify root hash for verity\n",
                program_invocation_short_name,
@@ -48,6 +50,7 @@ static int parse_argv(int argc, char *argv[]) {
                 ARG_VERSION = 0x100,
                 ARG_DISCARD,
                 ARG_ROOT_HASH,
+                ARG_FSCK,
         };
 
         static const struct option options[] = {
@@ -57,6 +60,7 @@ static int parse_argv(int argc, char *argv[]) {
                 { "read-only", no_argument,       NULL, 'r'           },
                 { "discard",   required_argument, NULL, ARG_DISCARD   },
                 { "root-hash", required_argument, NULL, ARG_ROOT_HASH },
+                { "fsck",      required_argument, NULL, ARG_FSCK      },
                 {}
         };
 
@@ -123,6 +127,14 @@ static int parse_argv(int argc, char *argv[]) {
                         break;
                 }
 
+                case ARG_FSCK:
+                        r = parse_boolean(optarg);
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to parse --fsck= parameter: %s", optarg);
+
+                        SET_FLAG(arg_flags, DISSECT_IMAGE_FSCK, r);
+                        break;
+
                 case '?':
                         return -EINVAL;
 
@@ -261,6 +273,8 @@ static int run(int argc, char *argv[]) {
                         return r;
 
                 r = dissected_image_mount(m, arg_path, UID_INVALID, arg_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");
 

src/nspawn/nspawn.c

@@ -3309,10 +3309,12 @@ static int outer_child(
 
                 r = dissected_image_mount(dissected_image, directory, arg_uid_shift,
                                           DISSECT_IMAGE_MOUNT_ROOT_ONLY|DISSECT_IMAGE_DISCARD_ON_LOOP|
-                                          (arg_read_only ? DISSECT_IMAGE_READ_ONLY : 0)|
+                                          (arg_read_only ? DISSECT_IMAGE_READ_ONLY : DISSECT_IMAGE_FSCK)|
                                           (arg_start_mode == START_BOOT ? DISSECT_IMAGE_VALIDATE_OS : 0));
+                if (r == -EUCLEAN)
+                        return log_error_errno(r, "File system check for image failed: %m");
                 if (r < 0)
-                        return r;
+                        return log_error_errno(r, "Failed to mount image root file system: %m");
         }
 
         r = determine_uid_shift(directory);
@@ -3396,9 +3398,11 @@ static int outer_child(
         if (dissected_image) {
                 /* Now we know the uid shift, let's now mount everything else that might be in the image. */
                 r = dissected_image_mount(dissected_image, directory, arg_uid_shift,
-                                          DISSECT_IMAGE_MOUNT_NON_ROOT_ONLY|DISSECT_IMAGE_DISCARD_ON_LOOP|(arg_read_only ? DISSECT_IMAGE_READ_ONLY : 0));
+                                          DISSECT_IMAGE_MOUNT_NON_ROOT_ONLY|DISSECT_IMAGE_DISCARD_ON_LOOP|(arg_read_only ? DISSECT_IMAGE_READ_ONLY : DISSECT_IMAGE_FSCK));
+                if (r == -EUCLEAN)
+                        return log_error_errno(r, "File system check for image failed: %m");
                 if (r < 0)
-                        return r;
+                        return log_error_errno(r, "Failed to mount image file system: %m");
         }
 
         if (arg_unified_cgroup_hierarchy == CGROUP_UNIFIED_UNKNOWN) {

src/shared/dissect-image.c

@@ -28,6 +28,7 @@
 #include "fd-util.h"
 #include "fileio.h"
 #include "fs-util.h"
+#include "fsck-util.h"
 #include "gpt.h"
 #include "hexdecoct.h"
 #include "hostname-util.h"
@@ -278,6 +279,29 @@ static int loop_wait_for_partitions_to_appear(
                                N_DEVICE_NODE_LIST_ATTEMPTS);
 }
 
+static void check_partition_flags(
+                const char *node,
+                unsigned long long pflags,
+                unsigned long long supported) {
+
+        assert(node);
+
+        /* Mask away all flags supported by this partition's type and the three flags the UEFI spec defines generically */
+        pflags &= ~(supported | GPT_FLAG_REQUIRED_PARTITION | GPT_FLAG_NO_BLOCK_IO_PROTOCOL | GPT_FLAG_LEGACY_BIOS_BOOTABLE);
+
+        if (pflags == 0)
+                return;
+
+        /* If there are other bits set, then log about it, to make things discoverable */
+        for (unsigned i = 0; i < sizeof(pflags) * 8; i++) {
+                unsigned long long bit = 1ULL << i;
+                if (!FLAGS_SET(pflags, bit))
+                        continue;
+
+                log_debug("Unexpected partition flag %llu set on %s!", bit, node);
+        }
+}
+
 #endif
 
 int dissect_image(
@@ -484,6 +508,8 @@ int dissect_image(
 
                         if (sd_id128_equal(type_id, GPT_HOME)) {
 
+                                check_partition_flags(node, pflags, GPT_FLAG_NO_AUTO|GPT_FLAG_READ_ONLY);
+
                                 if (pflags & GPT_FLAG_NO_AUTO)
                                         continue;
 
@@ -491,6 +517,8 @@ int dissect_image(
                                 rw = !(pflags & GPT_FLAG_READ_ONLY);
                         } else if (sd_id128_equal(type_id, GPT_SRV)) {
 
+                                check_partition_flags(node, pflags, GPT_FLAG_NO_AUTO|GPT_FLAG_READ_ONLY);
+
                                 if (pflags & GPT_FLAG_NO_AUTO)
                                         continue;
 
@@ -510,6 +538,8 @@ int dissect_image(
 
                         } else if (sd_id128_equal(type_id, GPT_XBOOTLDR)) {
 
+                                check_partition_flags(node, pflags, GPT_FLAG_NO_AUTO|GPT_FLAG_READ_ONLY);
+
                                 if (pflags & GPT_FLAG_NO_AUTO)
                                         continue;
 
@@ -519,6 +549,8 @@ int dissect_image(
 #ifdef GPT_ROOT_NATIVE
                         else if (sd_id128_equal(type_id, GPT_ROOT_NATIVE)) {
 
+                                check_partition_flags(node, pflags, GPT_FLAG_NO_AUTO|GPT_FLAG_READ_ONLY);
+
                                 if (pflags & GPT_FLAG_NO_AUTO)
                                         continue;
 
@@ -531,6 +563,8 @@ int dissect_image(
                                 rw = !(pflags & GPT_FLAG_READ_ONLY);
                         } else if (sd_id128_equal(type_id, GPT_ROOT_NATIVE_VERITY)) {
 
+                                check_partition_flags(node, pflags, GPT_FLAG_NO_AUTO|GPT_FLAG_READ_ONLY);
+
                                 if (pflags & GPT_FLAG_NO_AUTO)
                                         continue;
 
@@ -549,6 +583,8 @@ int dissect_image(
 #ifdef GPT_ROOT_SECONDARY
                         else if (sd_id128_equal(type_id, GPT_ROOT_SECONDARY)) {
 
+                                check_partition_flags(node, pflags, GPT_FLAG_NO_AUTO|GPT_FLAG_READ_ONLY);
+
                                 if (pflags & GPT_FLAG_NO_AUTO)
                                         continue;
 
@@ -561,6 +597,8 @@ int dissect_image(
                                 rw = !(pflags & GPT_FLAG_READ_ONLY);
                         } else if (sd_id128_equal(type_id, GPT_ROOT_SECONDARY_VERITY)) {
 
+                                check_partition_flags(node, pflags, GPT_FLAG_NO_AUTO|GPT_FLAG_READ_ONLY);
+
                                 if (pflags & GPT_FLAG_NO_AUTO)
                                         continue;
 
@@ -578,6 +616,8 @@ int dissect_image(
 #endif
                         else if (sd_id128_equal(type_id, GPT_SWAP)) {
 
+                                check_partition_flags(node, pflags, GPT_FLAG_NO_AUTO);
+
                                 if (pflags & GPT_FLAG_NO_AUTO)
                                         continue;
 
@@ -585,6 +625,8 @@ int dissect_image(
                                 fstype = "swap";
                         } else if (sd_id128_equal(type_id, GPT_LINUX_GENERIC)) {
 
+                                check_partition_flags(node, pflags, GPT_FLAG_NO_AUTO|GPT_FLAG_READ_ONLY);
+
                                 if (pflags & GPT_FLAG_NO_AUTO)
                                         continue;
 
@@ -601,6 +643,8 @@ int dissect_image(
 
                         } else if (sd_id128_equal(type_id, GPT_TMP)) {
 
+                                check_partition_flags(node, pflags, GPT_FLAG_NO_AUTO|GPT_FLAG_READ_ONLY);
+
                                 if (pflags & GPT_FLAG_NO_AUTO)
                                         continue;
 
@@ -609,6 +653,8 @@ int dissect_image(
 
                         } else if (sd_id128_equal(type_id, GPT_VAR)) {
 
+                                check_partition_flags(node, pflags, GPT_FLAG_NO_AUTO|GPT_FLAG_READ_ONLY);
+
                                 if (pflags & GPT_FLAG_NO_AUTO)
                                         continue;
 
@@ -851,6 +897,49 @@ static int is_loop_device(const char *path) {
         return true;
 }
 
+static int run_fsck(const char *node, const char *fstype) {
+        int r, exit_status;
+        pid_t pid;
+
+        assert(node);
+        assert(fstype);
+
+        r = fsck_exists(fstype);
+        if (r < 0) {
+                log_debug_errno(r, "Couldn't determine whether fsck for %s exists, proceeding anyway.", fstype);
+                return 0;
+        }
+        if (r == 0) {
+                log_debug("Not checking partition %s, as fsck for %s does not exist.", node, fstype);
+                return 0;
+        }
+
+        r = safe_fork("(fsck)", FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_RLIMIT_NOFILE_SAFE|FORK_DEATHSIG|FORK_NULL_STDIO, &pid);
+        if (r < 0)
+                return log_debug_errno(r, "Failed to fork off fsck: %m");
+        if (r == 0) {
+                /* Child */
+                execl("/sbin/fsck", "/sbin/fsck", "-aT", node, NULL);
+                log_debug_errno(errno, "Failed to execl() fsck: %m");
+                _exit(FSCK_OPERATIONAL_ERROR);
+        }
+
+        exit_status = wait_for_terminate_and_check("fsck", pid, 0);
+        if (exit_status < 0)
+                return log_debug_errno(exit_status, "Failed to fork off /sbin/fsck: %m");
+
+        if ((exit_status & ~FSCK_ERROR_CORRECTED) != FSCK_SUCCESS) {
+                log_debug("fsck failed with exit status %i.", exit_status);
+
+                if ((exit_status & (FSCK_SYSTEM_SHOULD_REBOOT|FSCK_ERRORS_LEFT_UNCORRECTED)) != 0)
+                        return log_debug_errno(SYNTHETIC_ERRNO(EUCLEAN), "File system is corrupted, refusing.");
+
+                log_debug("Ignoring fsck error.");
+        }
+
+        return 0;
+}
+
 static int mount_partition(
                 DissectedPartition *m,
                 const char *where,
@@ -878,6 +967,12 @@ static int mount_partition(
 
         rw = m->rw && !(flags & DISSECT_IMAGE_READ_ONLY);
 
+        if (FLAGS_SET(flags, DISSECT_IMAGE_FSCK) && rw) {
+                r = run_fsck(node, fstype);
+                if (r < 0)
+                        return r;
+        }
+
         if (directory) {
                 r = chase_symlinks(directory, where, CHASE_PREFIX_ROOT, &chased, NULL);
                 if (r < 0)

src/shared/dissect-image.h

@@ -62,6 +62,7 @@ typedef enum DissectImageFlags {
         DISSECT_IMAGE_VALIDATE_OS         = 1 << 8,  /* Refuse mounting images that aren't identifiable as OS images */
         DISSECT_IMAGE_NO_UDEV             = 1 << 9,  /* Don't wait for udev initializing things */
         DISSECT_IMAGE_RELAX_VAR_CHECK     = 1 << 10, /* Don't insist that the UUID of /var is hashed from /etc/machine-id */
+        DISSECT_IMAGE_FSCK                = 1 << 11, /* File system check the partition before mounting (no effect when combined with DISSECT_IMAGE_READ_ONLY) */
 } DissectImageFlags;
 
 struct DissectedImage {

src/shared/gpt.h

@@ -58,7 +58,9 @@
 #  define GPT_ROOT_NATIVE_VERITY GPT_ROOT_ARM_VERITY
 #endif
 
+#define GPT_FLAG_REQUIRED_PARTITION (1ULL << 0)
 #define GPT_FLAG_NO_BLOCK_IO_PROTOCOL (1ULL << 1)
+#define GPT_FLAG_LEGACY_BIOS_BOOTABLE (1ULL << 2)
 
 /* Flags we recognize on the root, swap, home and srv partitions when
  * doing auto-discovery. These happen to be identical to what