extension-release: search for other files if expected name not found

In some cases image names are unpredictable - some orchestrators/deployment
tools like to mangle names to suit their internal formats. In these cases,
the requirement that the extension-release file matches exactly the image
name where it's contained cannot work.

Allow falling back to loading the first regular file which name starts with
'extension-release' located in /usr/lib/extension-release.d/ and tagged with
a user.extension-release.strict extended attribute with a true value, if the
one with the expected name cannot be found.

diff --git a/src/basic/os-util.c b/src/basic/os-util.c
index 51c685bc6a87e2c85a6de76bb730471fac5507ab..1d69ecc58622c0616c3dceb083ae3adbce6e3a87 100644 (file)
--- a/src/basic/os-util.c
+++ b/src/basic/os-util.c
@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
 #include "alloc-util.h"
+#include "dirent-util.h"
 #include "env-file.h"
 #include "env-util.h"
 #include "fd-util.h"
@@ -8,10 +9,13 @@
 #include "fs-util.h"
 #include "macro.h"
 #include "os-util.h"
+#include "parse-util.h"
 #include "path-util.h"
+#include "stat-util.h"
 #include "string-util.h"
 #include "strv.h"
 #include "utf8.h"
+#include "xattr-util.h"
 
 bool image_name_is_valid(const char *s) {
         if (!filename_is_valid(s))
@@ -41,8 +45,8 @@ int path_is_extension_tree(const char *path, const char *extension) {
         if (laccess(path, F_OK) < 0)
                 return -errno;
 
-        /* We use /usr/lib/extension-release.d/extension-release.NAME as flag file if something is a system extension,
-         * and {/etc|/usr/lib}/os-release as flag file if something is an OS (in case extension == NULL) */
+        /* We use /usr/lib/extension-release.d/extension-release[.NAME] as flag for something being a system extension,
+         * and {/etc|/usr/lib}/os-release as a flag for something being an OS (when not an extension). */
         r = open_extension_release(path, extension, NULL, NULL);
         if (r == -ENOENT) /* We got nothing */
                 return 0;
@@ -67,6 +71,91 @@ int open_extension_release(const char *root, const char *extension, char **ret_p
                 r = chase_symlinks(extension_full_path, root, CHASE_PREFIX_ROOT,
                                    ret_path ? &q : NULL,
                                    ret_fd ? &fd : NULL);
+                /* Cannot find the expected extension-release file? The image filename might have been
+                 * mangled on deployment, so fallback to checking for any file in the extension-release.d
+                 * directory, and return the first one with a user.extension-release xattr instead.
+                 * The user.extension-release.strict xattr is checked to ensure the author of the image
+                 * considers it OK if names do not match. */
+                if (r == -ENOENT) {
+                        _cleanup_free_ char *extension_release_dir_path = NULL;
+                        _cleanup_closedir_ DIR *extension_release_dir = NULL;
+
+                        r = chase_symlinks_and_opendir("/usr/lib/extension-release.d/", root, CHASE_PREFIX_ROOT,
+                                                       &extension_release_dir_path, &extension_release_dir);
+                        if (r < 0)
+                                return r;
+
+                        r = -ENOENT;
+                        struct dirent *de;
+                        FOREACH_DIRENT(de, extension_release_dir, return -errno) {
+                                int k;
+
+                                if (!IN_SET(de->d_type, DT_REG, DT_UNKNOWN))
+                                        continue;
+
+                                const char *image_name = startswith(de->d_name, "extension-release.");
+                                if (!image_name)
+                                        continue;
+
+                                if (!image_name_is_valid(image_name))
+                                        continue;
+
+                                /* We already chased the directory, and checked that
+                                 * this is a real file, so we shouldn't fail to open it. */
+                                _cleanup_close_ int extension_release_fd = openat(dirfd(extension_release_dir),
+                                                                                  de->d_name,
+                                                                                  O_PATH|O_CLOEXEC|O_NOFOLLOW);
+                                if (extension_release_fd < 0)
+                                        return log_debug_errno(errno,
+                                                               "Failed to open extension-release file %s/%s: %m",
+                                                               extension_release_dir_path,
+                                                               de->d_name);
+
+                                /* Really ensure it is a regular file after we open it. */
+                                if (fd_verify_regular(extension_release_fd) < 0)
+                                        continue;
+
+                                /* No xattr or cannot parse it? Then skip this. */
+                                _cleanup_free_ char *extension_release_xattr = NULL;
+                                k = fgetxattrat_fake_malloc(extension_release_fd, NULL, "user.extension-release.strict", AT_EMPTY_PATH, &extension_release_xattr);
+                                if (k < 0 && !ERRNO_IS_NOT_SUPPORTED(k) && k != -ENODATA)
+                                        log_debug_errno(k,
+                                                        "Failed to read 'user.extension-release.strict' extended attribute from extension-release file %s/%s: %m",
+                                                        extension_release_dir_path,
+                                                        de->d_name);
+                                if (k < 0)
+                                        continue;
+
+                                /* Explicitly set to request strict matching? Skip it. */
+                                k = parse_boolean(extension_release_xattr);
+                                if (k < 0)
+                                        log_debug_errno(k,
+                                                        "Failed to parse 'user.extension-release.strict' extended attribute value from extension-release file %s/%s: %m",
+                                                        extension_release_dir_path,
+                                                        de->d_name);
+                                if (k < 0 || k > 0)
+                                        continue;
+
+                                /* We already found what we were looking for, but there's another candidate?
+                                 * We treat this as an error, as we want to enforce that there are no ambiguities
+                                 * in case we are in the fallback path.*/
+                                if (r == 0) {
+                                        r = -ENOTUNIQ;
+                                        break;
+                                }
+
+                                r = 0; /* Found it! */
+
+                                if (ret_fd)
+                                        fd = TAKE_FD(extension_release_fd);
+
+                                if (ret_path) {
+                                        q = path_join(extension_release_dir_path, de->d_name);
+                                        if (!q)
+                                                return -ENOMEM;
+                                }
+                        }
+                }
         } else {
                 const char *p;
 

diff --git a/src/shared/dissect-image.c b/src/shared/dissect-image.c
index 27b9ac9569e7674e094b2cbcffc8fc85e15219b3..32b21eb71b0bbf9a65e3c7eecac3d05bf43cf28c 100644 (file)
--- a/src/shared/dissect-image.c
+++ b/src/shared/dissect-image.c
@@ -2538,13 +2538,13 @@ int dissected_image_acquire_metadata(DissectedImage *m) {
                 _META_MAX,
         };
 
-        static const char *paths[_META_MAX] = {
+        static const char *const paths[_META_MAX] = {
                 [META_HOSTNAME]          = "/etc/hostname\0",
                 [META_MACHINE_ID]        = "/etc/machine-id\0",
                 [META_MACHINE_INFO]      = "/etc/machine-info\0",
-                [META_OS_RELEASE]        = "/etc/os-release\0"
-                                           "/usr/lib/os-release\0",
-                [META_EXTENSION_RELEASE] = NULL,
+                [META_OS_RELEASE]        = ("/etc/os-release\0"
+                                           "/usr/lib/os-release\0"),
+                [META_EXTENSION_RELEASE] = "extension-release\0", /* Used only for logging. */
         };
 
         _cleanup_strv_free_ char **machine_info = NULL, **os_release = NULL, **extension_release = NULL;
@@ -2561,17 +2561,6 @@ int dissected_image_acquire_metadata(DissectedImage *m) {
 
         assert(m);
 
-        /* As per the os-release spec, if the image is an extension it will have a file
-         * named after the image name in extension-release.d/ */
-        if (m->image_name) {
-                char *ext;
-
-                ext = strjoina("/usr/lib/extension-release.d/extension-release.", m->image_name, "0");
-                ext[strlen(ext) - 1] = '\0'; /* Extra \0 for NULSTR_FOREACH using placeholder from above */
-                paths[META_EXTENSION_RELEASE] = ext;
-        } else
-                log_debug("No image name available, will skip extension-release metadata");
-
         for (; n_meta_initialized < _META_MAX; n_meta_initialized ++) {
                 if (!paths[n_meta_initialized]) {
                         fds[2*n_meta_initialized] = fds[2*n_meta_initialized+1] = -1;
@@ -2625,11 +2614,25 @@ int dissected_image_acquire_metadata(DissectedImage *m) {
 
                         fds[2*k] = safe_close(fds[2*k]);
 
-                        NULSTR_FOREACH(p, paths[k]) {
-                                fd = chase_symlinks_and_open(p, t, CHASE_PREFIX_ROOT, O_RDONLY|O_CLOEXEC|O_NOCTTY, NULL);
-                                if (fd >= 0)
-                                        break;
-                        }
+                        if (k == META_EXTENSION_RELEASE) {
+                                /* As per the os-release spec, if the image is an extension it will have a file
+                                 * named after the image name in extension-release.d/ - we use the image name
+                                 * and try to resolve it with the extension-release helpers, as sometimes
+                                 * the image names are mangled on deployment and do not match anymore.
+                                 * Unlike other paths this is not fixed, and the image name
+                                 * can be mangled on deployment, so by calling into the helper
+                                 * we allow a fallback that matches on the first extension-release
+                                 * file found in the directory, if one named after the image cannot
+                                 * be found first. */
+                                r = open_extension_release(t, m->image_name, NULL, &fd);
+                                if (r < 0)
+                                        fd = r; /* Propagate the error. */
+                        } else
+                                NULSTR_FOREACH(p, paths[k]) {
+                                        fd = chase_symlinks_and_open(p, t, CHASE_PREFIX_ROOT, O_RDONLY|O_CLOEXEC|O_NOCTTY, NULL);
+                                        if (fd >= 0)
+                                                break;
+                                }
                         if (fd < 0) {
                                 log_debug_errno(fd, "Failed to read %s file of image, ignoring: %m", paths[k]);
                                 fds[2*k+1] = safe_close(fds[2*k+1]);

diff --git a/test/test-functions b/test/test-functions
index abe421c505c0c5f322f92353418fc520949b7885..27508957debc14d66914b37ef8b3a5eb5ea717e0 100644 (file)
--- a/test/test-functions
+++ b/test/test-functions
@@ -626,8 +626,9 @@ EOF
 
         export initdir="$TESTDIR/app1"
         mkdir -p "$initdir/usr/lib/extension-release.d" "$initdir/usr/lib/systemd/system" "$initdir/opt"
-        grep "^ID=" "$os_release" >"$initdir/usr/lib/extension-release.d/extension-release.app1"
-        echo "${version_id}" >>"$initdir/usr/lib/extension-release.d/extension-release.app1"
+        grep "^ID=" "$os_release" >"$initdir/usr/lib/extension-release.d/extension-release.app2"
+        echo "${version_id}" >>"$initdir/usr/lib/extension-release.d/extension-release.app2"
+        setfattr -n user.extension-release.strict -v false "$initdir/usr/lib/extension-release.d/extension-release.app2"
         cat >"$initdir/usr/lib/systemd/system/app1.service" <<EOF
 [Service]
 Type=oneshot
@@ -638,7 +639,7 @@ EOF
 #!/bin/bash
 set -e
 test -e /usr/lib/os-release
-cat /usr/lib/extension-release.d/extension-release.app1
+cat /usr/lib/extension-release.d/extension-release.app2
 EOF
         chmod +x "$initdir/opt/script1.sh"
         echo MARKER=1 >"$initdir/usr/lib/systemd/system/other_file"

diff --git a/test/units/testsuite-29.sh b/test/units/testsuite-29.sh
index 3408e6d71acb86167fae93e97caf84667035a920..77bb6db15a70944cc50639ecdbc032af3c4c1f04 100755 (executable)
--- a/test/units/testsuite-29.sh
+++ b/test/units/testsuite-29.sh
@@ -5,6 +5,11 @@ set -eux
 set -o pipefail
 
 export SYSTEMD_LOG_LEVEL=debug
+mkdir -p /run/systemd/system/systemd-portabled.service.d/
+cat <<EOF >/run/systemd/system/systemd-portabled.service.d/override.conf
+[Service]
+Environment=SYSTEMD_LOG_LEVEL=debug
+EOF
 
 portablectl attach --now --runtime /usr/share/minimal_0.raw app0
 
@@ -63,24 +68,31 @@ portablectl detach --now --enable --runtime /tmp/minimal_1 app0
 
 portablectl list | grep -q -F "No images."
 
-root="/usr/share/minimal_0.raw"
-app1="/usr/share/app1.raw"
+portablectl attach --now --runtime --extension /usr/share/app0.raw /usr/share/minimal_0.raw app0
 
-portablectl attach --now --runtime --extension ${app1} ${root} app1
+systemctl is-active app0.service
+
+portablectl reattach --now --runtime --extension /usr/share/app0.raw /usr/share/minimal_1.raw app0
+
+systemctl is-active app0.service
+
+portablectl detach --now --runtime --extension /usr/share/app0.raw /usr/share/minimal_1.raw app0
+
+portablectl attach --now --runtime --extension /usr/share/app1.raw /usr/share/minimal_0.raw app1
 
 systemctl is-active app1.service
 
-portablectl reattach --now --runtime --extension ${app1} ${root} app1
+portablectl reattach --now --runtime --extension /usr/share/app1.raw /usr/share/minimal_1.raw app1
 
 systemctl is-active app1.service
 
-portablectl detach --now --runtime --extension ${app1} ${root} app1
+portablectl detach --now --runtime --extension /usr/share/app1.raw /usr/share/minimal_1.raw app1
 
 # portablectl also works with directory paths rather than images
 
 mkdir /tmp/rootdir /tmp/app1 /tmp/overlay
-mount ${app1} /tmp/app1
-mount ${root} /tmp/rootdir
+mount /usr/share/app1.raw /tmp/app1
+mount /usr/share/minimal_0.raw /tmp/rootdir
 mount -t overlay overlay -o lowerdir=/tmp/app1:/tmp/rootdir /tmp/overlay
 
 portablectl attach --copy=symlink --now --runtime /tmp/overlay app1

diff --git a/test/units/testsuite-50.sh b/test/units/testsuite-50.sh
index 081a8bcb953d2458bd3fd363fad320261c3de5f9..9125918ea9db75cc3c133fc44618887711c040c7 100755 (executable)
--- a/test/units/testsuite-50.sh
+++ b/test/units/testsuite-50.sh
@@ -235,7 +235,7 @@ systemd-run -P --property ExtensionImages=/usr/share/app0.raw --property RootIma
 systemd-run -P --property ExtensionImages=/usr/share/app0.raw --property RootImage="${image}.raw" cat /usr/lib/systemd/system/some_file | grep -q -F "MARKER=1"
 systemd-run -P --property ExtensionImages="/usr/share/app0.raw /usr/share/app1.raw" --property RootImage="${image}.raw" cat /opt/script0.sh | grep -q -F "extension-release.app0"
 systemd-run -P --property ExtensionImages="/usr/share/app0.raw /usr/share/app1.raw" --property RootImage="${image}.raw" cat /usr/lib/systemd/system/some_file | grep -q -F "MARKER=1"
-systemd-run -P --property ExtensionImages="/usr/share/app0.raw /usr/share/app1.raw" --property RootImage="${image}.raw" cat /opt/script1.sh | grep -q -F "extension-release.app1"
+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"
 cat >/run/systemd/system/testservice-50e.service <<EOF
 [Service]