Add support for default standalone boot modes

When a standalone is cloned from a template, the usual default boot
mode of the standalone is the same as the boot mode the template
originally used. In some instances this is undesirable; Kicksecure for
instance puts its templates into a "sysmaint" boot mode that impairs
standalone functionality.

To fix this, add a new qvm-feature, "boot-mode.standalone-default",
which states which boot mode a standalone should be switched to when
its root volume is cloned from any other VM. (Note that cloning a
standalone from another standalone will switch it to the boot mode
specified by "boot-mode.standalone-default", cloning a template isn't
the only way to trigger this.)

Allows fixing QubesOS/qubes-issues#10514, but
does not fix this bug by itself.

Author: ArrayBolt3

qubes/ext/core_features.py

@@ -194,6 +194,16 @@ async def qubes_features_request(self, vm, event, untrusted_features):
             ) and hasattr(vm, "appvm_default_bootmode"):
                 bootmode_value = untrusted_feature_value
                 vm.features["boot-mode.appvm-default"] = bootmode_value
+        if "boot-mode.standalone-default" in untrusted_features:
+            untrusted_feature_value = untrusted_features[
+                "boot-mode.standalone-default"
+            ]
+            if (
+                f"boot-mode.kernelopts.{untrusted_feature_value}" in vm.features
+                or untrusted_feature_value == "default"
+            ) and hasattr(vm, "standalone_default_bootmode"):
+                bootmode_value = untrusted_feature_value
+                vm.features["boot-mode.standalone-default"] = bootmode_value
 
         # allow VMs to switch on anon-timezone, but do not permit dropping it
         if "anon-timezone" in untrusted_features:

qubes/storage/__init__.py

@@ -929,9 +929,13 @@ async def import_volume(self, dst_volume: Volume, src_volume: Volume):
                 f"data"
             )
 
-        return await qubes.utils.coro_maybe(
+        import_rslt = await qubes.utils.coro_maybe(
             dst_volume.import_volume(src_volume)
         )
+        await self.vm.fire_event_async(
+            "domain-import-volume", name=dst_volume.name, source=src_volume
+        )
+        return import_rslt
 
 
 class VolumesCollection:

qubes/tests/ext.py

@@ -1677,6 +1677,75 @@ def test_057_bootmode_default_user_default_bootmode(self):
             ],
         )
 
+    def test_058_bootmode_standalone_default_good(self):
+        del self.vm.template
+        self.loop.run_until_complete(
+            self.ext.qubes_features_request(
+                self.vm,
+                "features-request",
+                untrusted_features={
+                    "boot-mode.kernelopts.orig-mode": "test1",
+                    "boot-mode.kernelopts.new-mode": "test2",
+                    "boot-mode.standalone-default": "new-mode",
+                }
+            )
+        )
+        self.assertListEqual(
+            self.vm.mock_calls,
+            [
+                ("features.items", (), {}),
+                (
+                    "features.__setitem__",
+                    ("boot-mode.kernelopts.orig-mode", "test1"),
+                    {},
+                ),
+                (
+                    "features.__setitem__",
+                    ("boot-mode.kernelopts.new-mode", "test2"),
+                    {},
+                ),
+                (
+                    "features.__setitem__",
+                    ("boot-mode.standalone-default", "new-mode"),
+                    {},
+                ),
+                ("features.get", ("qrexec", False), {}),
+                ("features.get", ("qrexec", False), {}),
+            ]
+        )
+
+    def test_059_bootmode_standalone_default_bad(self):
+        del self.vm.template
+        self.loop.run_until_complete(
+            self.ext.qubes_features_request(
+                self.vm,
+                "features-request",
+                untrusted_features={
+                    "boot-mode.kernelopts.orig-mode": "test1",
+                    "boot-mode.kernelopts.new-mode": "test2",
+                    "boot-mode.standalone-default": "missing-mode",
+                }
+            )
+        )
+        self.assertListEqual(
+            self.vm.mock_calls,
+            [
+                ("features.items", (), {}),
+                (
+                    "features.__setitem__",
+                    ("boot-mode.kernelopts.orig-mode", "test1"),
+                    {},
+                ),
+                (
+                    "features.__setitem__",
+                    ("boot-mode.kernelopts.new-mode", "test2"),
+                    {},
+                ),
+                ("features.get", ("qrexec", False), {}),
+                ("features.get", ("qrexec", False), {}),
+            ]
+        )
+
     def test_060_anon_timezone_set(self):
         del self.vm.template
         self.loop.run_until_complete(

qubes/tests/integ/storage.py

@@ -31,6 +31,7 @@
 import qubes.tests.storage_zfs
 import qubes.utils
 import qubes.vm.appvm
+import qubes.vm.standalonevm
 
 
 class StorageTestMixin(object):
@@ -46,6 +47,20 @@ def setUp(self):
             qubes.vm.appvm.AppVM, name=self.make_vm_name("vm2"), label="red"
         )
         self.loop.run_until_complete(self.vm2.create_on_disk())
+        self.standalone_vm1 = self.app.add_new_vm(
+            qubes.vm.standalonevm.StandaloneVM,
+            name=self.make_vm_name("standalone-vm1"),
+            label="red",
+        )
+        self.standalone_vm1.clone_properties(self.app.domains[self.template])
+        self.standalone_vm1.features.update(
+            self.app.domains[self.template].features
+        )
+        self.loop.run_until_complete(
+            self.standalone_vm1.clone_disk_files(
+                self.app.domains[self.template]
+            )
+        )
         self.pool = None
         self.init_pool()
         self.app.save()
@@ -485,6 +500,25 @@ async def _test_006_no_revisions(self):
         )
         self.assertEqual(stdout, b"test123")
 
+    def test_007_standalone_clone_boot_mode_transition(self):
+        return self.loop.run_until_complete(
+            self._test_007_standalone_clone_boot_mode_transition()
+        )
+
+    async def _test_007_standalone_clone_boot_mode_transition(self):
+        standalone_vm1.features["boot-mode.kernelopts.orig-mode"] = "test1"
+        standalone_vm1.features["boot-mode.kernelopts.new-mode"] = "test2"
+        standalone_vm1.features["boot-mode.active"] = "orig-mode"
+        standalone_vm1.features["boot-mode.standalone-default"] = "new-mode"
+        template_rootvol = self.template.storage.get_volume("root")
+        standalone_vm1_rootvol = self.standalone_vm1.storage.get_volume("root")
+        await qubes.utils.coro_maybe(
+            standalone_vm1_rootvol.import_volume(template_rootvol)
+        )
+        self.assertEqual(
+            standalone_vm1.features["boot-mode.active"], "new-mode"
+        )
+
 
 class StorageFile(StorageTestMixin, qubes.tests.SystemTestCase):
     def init_pool(self):

qubes/vm/qubesvm.py

@@ -668,6 +668,15 @@ class QubesVM(qubes.vm.mix.net.NetVMMixin, qubes.vm.LocalVM):
             :param event: Event name (``'domain-tag-delete:' tag``)
             :param tag: tag name
 
+        .. event:: domain-import-volume (subject, event, name, source)
+
+            A volume has been imported.
+
+            :param subject: Event emitter (the qube object)
+            :param event: Event name (``'domain-import-volume'``)
+            :param name: Destination volume name
+            :param source: Source volume
+
         .. event:: features-request (subject, event, *, untrusted_features)
 
             The domain is performing a features request.

qubes/vm/standalonevm.py

@@ -62,3 +62,15 @@ def __init__(self, *args, **kwargs):
             },
         }
         super().__init__(*args, **kwargs)
+
+    @qubes.events.handler("domain-import-volume")
+    def on_domain_import_volume(self, event, name, source):
+        # pylint: disable=unused-argument
+        if name != "root":
+            return
+        if "boot-mode.standalone-default" in self.features:
+            bootmode_value = self.features["boot-mode.standalone-default"]
+            if bootmode_value == "default":
+                self.features["boot-mode.active"] = "default"
+            if f"boot-mode.kernelopts.{bootmode_value}" in self.features:
+                self.features["boot-mode.active"] = bootmode_value