Revert to red label while restoring on missing labels

If we allow users to create custom labels and they backup such qubes,
restore operation will fail on new systems without those custom labels.
Fix this by reverting to red label and allow users to restore their
backup.

fixes: QubesOS/qubes-issues#9781

Author: alimirjamali

.gitlab-ci.yml

@@ -20,7 +20,7 @@ checks:tests:
   - ci/codecov-wrapper
   before_script:
   - sudo dnf install -y openssl python3-rpm sequoia-sqv python3-xlib libnotify
-    xorg-x11-server-Xvfb
+    xorg-x11-server-Xvfb scrypt
   - pip3 install --quiet -r ci/requirements.txt
   - git config --global --add safe.directory "$PWD"
   script:

qubesadmin/backup/restore.py

@@ -2020,6 +2020,12 @@ def _restore_vms_metadata(self, restore_info):
                 # can't create vm, but need backup info
                 new_vm = self.backup_app.domains[vm_name]
             else:
+                # do not fail if VM had a custom label. revert to red label
+                if not vm.label in self.app.labels:
+                    self.log.warning(
+                        'Reverting to red label while restoring %s ' \
+                        'since %s label does not exist', vm.name, vm.label)
+                    vm.label = "red"
                 try:
                     # first only create VMs, later setting may require other VMs
                     # be already created

qubesadmin/tests/backup/backupcompatibility.py

@@ -695,7 +695,7 @@
         },
         'test-net': {
             'klass': 'AppVM',
-            'label': 'red',
+            'label': 'scarlet',
             'properties': {
                 'maxmem': '300',
                 'memory': '300',
@@ -749,8 +749,11 @@ def assertCorrectlyConverted(self, backup_app, expected_data):
                 expected_data['domains'][vm]['template'], vm)
             self.assertEqual(backup_app.domains[vm].klass,
                 expected_data['domains'][vm]['klass'], vm)
-            self.assertEqual(backup_app.domains[vm].label,
-                expected_data['domains'][vm]['label'], vm)
+            if expected_data['domains'][vm]['label'] == 'scarlet':
+                self.assertEqual(backup_app.domains[vm].label, 'red', vm)
+            else:
+                self.assertEqual(backup_app.domains[vm].label,
+                    expected_data['domains'][vm]['label'], vm)
             self.assertEqual(backup_app.domains[vm].backup_path,
                 expected_data['domains'][vm]['backup_path'], vm)
             self.assertEqual(backup_app.domains[vm].included_in_backup,
@@ -1511,6 +1514,9 @@ def test_210_r2(self):
             b'fedora-25 class=TemplateVM state=Halted\n'
             b'testvm class=AppVM state=Running\n'
         )
+        self.app.expected_calls[('dom0', 'admin.label.List', None, None)] = (
+            b'0\0red\norange\nyellow\ngreen\ngray\nblue\npurple\nblack\n'
+        )
         self.app.expected_calls[
             ('dom0', 'admin.property.Get', 'default_template', None)] = \
             b'0\0default=no type=vm fedora-25'
@@ -1579,6 +1585,9 @@ def test_220_r2_encrypted(self):
             b'fedora-25 class=TemplateVM state=Halted\n'
             b'testvm class=AppVM state=Running\n'
         )
+        self.app.expected_calls[('dom0', 'admin.label.List', None, None)] = (
+            b'0\0red\norange\nyellow\ngreen\ngray\nblue\npurple\nblack\n'
+        )
         self.app.expected_calls[
             ('dom0', 'admin.property.Get', 'default_template', None)] = \
             b'0\0default=no type=vm fedora-25'
@@ -1647,6 +1656,9 @@ def test_230_r2_uncompressed(self):
             b'fedora-25 class=TemplateVM state=Halted\n'
             b'testvm class=AppVM state=Running\n'
         )
+        self.app.expected_calls[('dom0', 'admin.label.List', None, None)] = (
+            b'0\0red\norange\nyellow\ngreen\ngray\nblue\npurple\nblack\n'
+        )
         self.app.expected_calls[
             ('dom0', 'admin.property.Get', 'default_template', None)] = \
             b'0\0default=no type=vm fedora-25'