Merge pull request #14390 from poettering/gpt-var-tmp

introduce GPT partition types for /var and /var/tmp and support them for auto-discovery

src/shared/dissect-image.c

@@ -598,6 +598,43 @@ int dissect_image(
                                         if (!generic_node)
                                                 return -ENOMEM;
                                 }
+
+                        } else if (sd_id128_equal(type_id, GPT_TMP)) {
+
+                                if (pflags & GPT_FLAG_NO_AUTO)
+                                        continue;
+
+                                designator = PARTITION_TMP;
+                                rw = !(pflags & GPT_FLAG_READ_ONLY);
+
+                        } else if (sd_id128_equal(type_id, GPT_VAR)) {
+
+                                if (pflags & GPT_FLAG_NO_AUTO)
+                                        continue;
+
+                                if (!FLAGS_SET(flags, DISSECT_IMAGE_RELAX_VAR_CHECK)) {
+                                        sd_id128_t var_uuid;
+
+                                        /* For /var we insist that the uuid of the partition matches the
+                                         * HMAC-SHA256 of the /var GPT partition type uuid, keyed by machine
+                                         * ID. Why? Unlike the other partitions /var is inherently
+                                         * installation specific, hence we need to be careful not to mount it
+                                         * in the wrong installation. By hashing the partition UUID from
+                                         * /etc/machine-id we can securely bind the partition to the
+                                         * installation. */
+
+                                        r = sd_id128_get_machine_app_specific(GPT_VAR, &var_uuid);
+                                        if (r < 0)
+                                                return r;
+
+                                        if (!sd_id128_equal(var_uuid, id)) {
+                                                log_debug("Found a /var/ partition, but its UUID didn't match our expectations, ignoring.");
+                                                continue;
+                                        }
+                                }
+
+                                designator = PARTITION_VAR;
+                                rw = !(pflags & GPT_FLAG_READ_ONLY);
                         }
 
                         if (designator != _PARTITION_DESIGNATOR_INVALID) {
@@ -910,6 +947,14 @@ int dissected_image_mount(DissectedImage *m, const char *where, uid_t uid_shift,
         if (r < 0)
                 return r;
 
+        r = mount_partition(m->partitions + PARTITION_VAR, where, "/var", uid_shift, flags);
+        if (r < 0)
+                return r;
+
+        r = mount_partition(m->partitions + PARTITION_TMP, where, "/var/tmp", uid_shift, flags);
+        if (r < 0)
+                return r;
+
         boot_mounted = mount_partition(m->partitions + PARTITION_XBOOTLDR, where, "/boot", uid_shift, flags);
         if (boot_mounted < 0)
                 return boot_mounted;
@@ -1333,7 +1378,8 @@ int dissected_image_acquire_metadata(DissectedImage *m) {
                 [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_OS_RELEASE]   = "/etc/os-release\0"
+                                      "/usr/lib/os-release\0",
         };
 
         _cleanup_strv_free_ char **machine_info = NULL, **os_release = NULL;
@@ -1528,6 +1574,8 @@ static const char *const partition_designator_table[] = {
         [PARTITION_SWAP] = "swap",
         [PARTITION_ROOT_VERITY] = "root-verity",
         [PARTITION_ROOT_SECONDARY_VERITY] = "root-secondary-verity",
+        [PARTITION_TMP] = "tmp",
+        [PARTITION_VAR] = "var",
 };
 
 DEFINE_STRING_TABLE_LOOKUP(partition_designator, int);

src/shared/dissect-image.h

@@ -33,6 +33,8 @@ enum  {
         PARTITION_SWAP,
         PARTITION_ROOT_VERITY, /* verity data for the PARTITION_ROOT partition */
         PARTITION_ROOT_SECONDARY_VERITY, /* verity data for the PARTITION_ROOT_SECONDARY partition */
+        PARTITION_TMP,
+        PARTITION_VAR,
         _PARTITION_DESIGNATOR_MAX,
         _PARTITION_DESIGNATOR_INVALID = -1
 };
@@ -59,6 +61,7 @@ typedef enum DissectImageFlags {
         DISSECT_IMAGE_MOUNT_NON_ROOT_ONLY = 1 << 7,  /* Mount only non-root partitions */
         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 */
 } DissectImageFlags;
 
 struct DissectedImage {

src/shared/gpt.h

@@ -19,6 +19,8 @@
 #define GPT_SWAP        SD_ID128_MAKE(06,57,fd,6d,a4,ab,43,c4,84,e5,09,33,c8,4b,4f,4f)
 #define GPT_HOME        SD_ID128_MAKE(93,3a,c7,e1,2e,b4,4f,13,b8,44,0e,14,e2,ae,f9,15)
 #define GPT_SRV         SD_ID128_MAKE(3b,8f,84,25,20,e0,4f,3b,90,7f,1a,25,a7,6f,98,e8)
+#define GPT_VAR         SD_ID128_MAKE(4d,21,b0,16,b5,34,45,c2,a9,fb,5c,16,e0,91,fd,2d)
+#define GPT_TMP         SD_ID128_MAKE(7e,c6,f5,57,3b,c5,4a,ca,b2,93,16,ef,5d,f6,39,d1)
 
 /* Verity partitions for the root partitions above (we only define them for the root partitions, because only they are
  * are commonly read-only and hence suitable for verity). */

src/shared/machine-image.c

@@ -1171,7 +1171,7 @@ int image_read_metadata(Image *i) {
                 if (r < 0)
                         return r;
 
-                r = dissect_image(d->fd, NULL, 0, DISSECT_IMAGE_REQUIRE_ROOT, &m);
+                r = dissect_image(d->fd, NULL, 0, DISSECT_IMAGE_REQUIRE_ROOT|DISSECT_IMAGE_RELAX_VAR_CHECK, &m);
                 if (r < 0)
                         return r;