Use original filename for extension name check

The loading of an extension image from a symlink "NAME.raw" to
"NAME-VERSION.raw" failed because the release file name check worked
with the backing file of the loop device which already resolves the
symlink and thus the found name "NAME-VERSION" mismatched "NAME".
Pass the original filename and use it instead of the backing file
when available. This fixes the loading of "NAME.raw" extensions which
are a symlink to "NAME-VERSION.raw" as, e.g., may be the case when
systemd-sysupdate manages multiple versions.

Fixes https://github.com/systemd/systemd/issues/24293

src/core/namespace.c

@@ -2065,6 +2065,7 @@ int setup_namespace(
 
                 r = dissect_loop_device(
                                 loop_device,
+                                root_image,
                                 &verity,
                                 root_image_options,
                                 dissect_image_flags,

src/gpt-auto-generator/gpt-auto-generator.c

@@ -710,6 +710,7 @@ static int enumerate_partitions(dev_t devnum) {
 
         r = dissect_image(
                         fd,
+                        NULL,
                         NULL, NULL,
                         /* diskseq= */ 0,
                         UINT64_MAX,

src/portable/portable.c

@@ -367,6 +367,7 @@ static int portable_extract_by_path(
 
                 r = dissect_loop_device(
                                 d,
+                                path,
                                 NULL, NULL,
                                 DISSECT_IMAGE_READ_ONLY |
                                 DISSECT_IMAGE_GENERIC_ROOT |

src/shared/discover-image.c

@@ -1198,6 +1198,7 @@ int image_read_metadata(Image *i) {
 
                 r = dissect_loop_device(
                                 d,
+                                i->path,
                                 NULL, NULL,
                                 DISSECT_IMAGE_GENERIC_ROOT |
                                 DISSECT_IMAGE_REQUIRE_ROOT |

src/shared/dissect-image.c

@@ -193,6 +193,7 @@ static int make_partition_devname(
 
 int dissect_image(
                 int fd,
+                const char *original_path,
                 const VeritySettings *verity,
                 const MountOptions *mount_options,
                 uint64_t diskseq,
@@ -307,15 +308,29 @@ int dissect_image(
         r = sd_device_get_sysname(d, &sysname);
         if (r < 0)
                 return log_debug_errno(r, "Failed to get device sysname: %m");
-        if (startswith(sysname, "loop")) {
-                _cleanup_free_ char *name_stripped = NULL;
+        if (original_path) {
+                _cleanup_free_ char *extracted_filename = NULL, *name_stripped = NULL;
+                r = path_extract_filename(original_path, &extracted_filename);
+                if (r < 0)
+                        return r;
+                r = raw_strip_suffixes(extracted_filename, &name_stripped);
+                if (r < 0)
+                        return r;
+
+                free_and_replace(m->image_name, name_stripped);
+        } else if (startswith(sysname, "loop")) {
+                _cleanup_free_ char *extracted_filename = NULL, *name_stripped = NULL;
                 const char *full_path;
 
+                /* Note that the backing_file reference resolves symlinks, while for sysext images we want the original path */
                 r = sd_device_get_sysattr_value(d, "loop/backing_file", &full_path);
                 if (r < 0)
                         log_debug_errno(r, "Failed to lookup image name via loop device backing file sysattr, ignoring: %m");
                 else {
-                        r = raw_strip_suffixes(basename(full_path), &name_stripped);
+                        r = path_extract_filename(full_path, &extracted_filename);
+                        if (r < 0)
+                                return r;
+                        r = raw_strip_suffixes(extracted_filename, &name_stripped);
                         if (r < 0)
                                 return r;
                 }
@@ -2812,7 +2827,7 @@ int dissect_loop_device_and_warn(
         if (!name)
                 name = ASSERT_PTR(loop->node);
 
-        r = dissect_loop_device(loop, verity, mount_options, flags, ret);
+        r = dissect_loop_device(loop, name, verity, mount_options, flags, ret);
         switch (r) {
 
         case -EOPNOTSUPP:
@@ -3078,6 +3093,7 @@ int verity_dissect_and_mount(
 
         r = dissect_loop_device(
                         loop_device,
+                        src,
                         &verity,
                         options,
                         dissect_image_flags,
@@ -3086,6 +3102,7 @@ int verity_dissect_and_mount(
         if (!verity.data_path && r == -ENOPKG)
                  r = dissect_loop_device(
                                 loop_device,
+                                src,
                                 &verity,
                                 options,
                                 dissect_image_flags | DISSECT_IMAGE_NO_PARTITION_TABLE,

src/shared/dissect-image.h

@@ -253,10 +253,10 @@ DEFINE_TRIVIAL_CLEANUP_FUNC(MountOptions*, mount_options_free_all);
 const char* mount_options_from_designator(const MountOptions *options, PartitionDesignator designator);
 
 int probe_filesystem(const char *node, char **ret_fstype);
-int dissect_image(int fd, const VeritySettings *verity, const MountOptions *mount_options, uint64_t diskseq, uint64_t uevent_seqnum_not_before, usec_t timestamp_not_before, DissectImageFlags flags, DissectedImage **ret);
-static inline int dissect_loop_device(const LoopDevice *loop, const VeritySettings *verity, const MountOptions *mount_options, DissectImageFlags flags, DissectedImage **ret) {
+int dissect_image(int fd, const char *original_path, const VeritySettings *verity, const MountOptions *mount_options, uint64_t diskseq, uint64_t uevent_seqnum_not_before, usec_t timestamp_not_before, DissectImageFlags flags, DissectedImage **ret);
+static inline int dissect_loop_device(const LoopDevice *loop, const char *original_path, const VeritySettings *verity, const MountOptions *mount_options, DissectImageFlags flags, DissectedImage **ret) {
         assert(loop);
-        return dissect_image(loop->fd, verity, mount_options, loop->diskseq, loop->uevent_seqnum_not_before, loop->timestamp_not_before, flags, ret);
+        return dissect_image(loop->fd, original_path, verity, mount_options, loop->diskseq, loop->uevent_seqnum_not_before, loop->timestamp_not_before, flags, ret);
 }
 int dissect_loop_device_and_warn(const char *name, const LoopDevice *loop, const VeritySettings *verity, const MountOptions *mount_options, DissectImageFlags flags, DissectedImage **ret);
 

src/test/test-loop-block.c

@@ -39,6 +39,7 @@ static void* thread_func(void *ptr) {
                 _cleanup_(loop_device_unrefp) LoopDevice *loop = NULL;
                 _cleanup_(umount_and_rmdir_and_freep) char *mounted = NULL;
                 _cleanup_(dissected_image_unrefp) DissectedImage *dissected = NULL;
+                _cleanup_free_ char *path = NULL;
 
                 if (now(CLOCK_MONOTONIC) >= end) {
                         log_notice("Time's up, exiting thread's loop");
@@ -56,7 +57,12 @@ static void* thread_func(void *ptr) {
 
                 log_notice("Acquired loop device %s, will mount on %s", loop->node, mounted);
 
-                r = dissect_loop_device(loop, NULL, NULL, DISSECT_IMAGE_READ_ONLY, &dissected);
+                r = fd_get_path(fd, &path);
+                if (r < 0)
+                        log_error_errno(r, "Failed to get path from fd: %m");
+                assert_se(r >= 0);
+
+                r = dissect_loop_device(loop, path, NULL, NULL, DISSECT_IMAGE_READ_ONLY, &dissected);
                 if (r < 0)
                         log_error_errno(r, "Failed dissect loopback device %s: %m", loop->node);
                 assert_se(r >= 0);
@@ -220,7 +226,7 @@ static int run(int argc, char *argv[]) {
         pthread_t threads[arg_n_threads];
         sd_id128_t id;
 
-        assert_se(dissect_loop_device(loop, NULL, NULL, 0, &dissected) >= 0);
+        assert_se(dissect_loop_device(loop, p, NULL, NULL, 0, &dissected) >= 0);
 
         assert_se(dissected->partitions[PARTITION_ESP].found);
         assert_se(dissected->partitions[PARTITION_ESP].node);
@@ -244,7 +250,7 @@ static int run(int argc, char *argv[]) {
         assert_se(make_filesystem(dissected->partitions[PARTITION_HOME].node, "ext4", "home", id, true) >= 0);
 
         dissected = dissected_image_unref(dissected);
-        assert_se(dissect_loop_device(loop, NULL, NULL, 0, &dissected) >= 0);
+        assert_se(dissect_loop_device(loop, p, NULL, NULL, 0, &dissected) >= 0);
 
         assert_se(mkdtemp_malloc(NULL, &mounted) >= 0);
 

test/units/testsuite-50.sh

@@ -318,6 +318,11 @@ systemd-run -P --property ExtensionImages="/usr/share/app0.raw /usr/share/app1.r
 systemd-run -P --property ExtensionImages="/usr/share/app0.raw /usr/share/app1.raw" --property RootImage="${image}.raw" cat /opt/script1.sh | grep -q -F "extension-release.app2"
 systemd-run -P --property ExtensionImages="/usr/share/app0.raw /usr/share/app1.raw" --property RootImage="${image}.raw" cat /usr/lib/systemd/system/other_file | grep -q -F "MARKER=1"
 systemd-run -P --property ExtensionImages=/usr/share/app-nodistro.raw --property RootImage="${image}.raw" cat /usr/lib/systemd/system/some_file | grep -q -F "MARKER=1"
+# Check that using a symlink to NAME-VERSION.raw works as long as the symlink has the correct name NAME.raw
+mkdir -p /usr/share/symlink-test/
+cp /usr/share/app-nodistro.raw /usr/share/symlink-test/app-nodistro-v1.raw
+ln -fs /usr/share/symlink-test/app-nodistro-v1.raw /usr/share/symlink-test/app-nodistro.raw
+systemd-run -P --property ExtensionImages=/usr/share/symlink-test/app-nodistro.raw --property RootImage="${image}.raw" cat /usr/lib/systemd/system/some_file | grep -q -F "MARKER=1"
 cat >/run/systemd/system/testservice-50e.service <<EOF
 [Service]
 MountAPIVFS=yes