Reject unsafe delete attachment calls

Due to how the Linux SCSI kernel driver works there are some storage
systems, such as iSCSI with shared targets, where a normal user can
access other projects' volume data connected to the same compute host
using the attachments REST API.

This affects both single and multi-pathed connections.

To prevent users from doing this, unintentionally or maliciously,
cinder-api will now reject some delete attachment requests that are
deemed unsafe.

Cinder will process the delete attachment request normally in the
following cases:

- The request comes from an OpenStack service that is sending the
  service token that has one of the roles in `service_token_roles`.
- Attachment doesn't have an instance_uuid value
- The instance for the attachment doesn't exist in Nova
- According to Nova the volume is not connected to the instance
- Nova is not using this attachment record

There are 3 operations in the actions REST API endpoint that can be used
for an attack:

- `os-terminate_connection`: Terminate volume attachment
- `os-detach`: Detach a volume
- `os-force_detach`: Force detach a volume

In this endpoint we just won't allow most requests not coming from a
service. The rules we apply are the same as for attachment delete
explained earlier, but in this case we may not have the attachment id
and be more restrictive.  This should not be a problem for normal
operations because:

- Cinder backup doesn't use the REST API but RPC calls via RabbitMQ
- Glance doesn't use this interface

Checking whether it's a service or not is done at the cinder-api level
by checking that the service user that made the call has at least one of
the roles in the `service_token_roles` configuration. These roles are
retrieved from keystone by the keystone middleware using the value of
the "X-Service-Token" header.

If Cinder is configured with `service_token_roles_required = true` and
an attacker provides non-service valid credentials the service will
return a 401 error, otherwise it'll return 409 as if a normal user had
made the call without the service token.

Closes-Bug: #2004555
Change-Id: I612905a1bf4a1706cce913c0d8a6df7a240d599a
(cherry picked from commit 6df1839bdf)
Conflicts:
	cinder/exception.py

api-ref/source/v3/attachments.inc

@@ -41,6 +41,20 @@ Delete attachment
 
 Deletes an attachment.
 
+For security reasons (see bug `#2004555
+<https://bugs.launchpad.net/nova/+bug/2004555>`_) the Block Storage API rejects
+REST API calls manually made from users with a 409 status code if there is a
+Nova instance currently using the attachment, which happens when all the
+following conditions are met:
+
+- Attachment has an instance uuid
+- VM exists in Nova
+- Instance has the volume attached
+- Attached volume in instance is using the attachment
+
+Calls coming from other OpenStack services (like the Compute Service) are
+always accepted.
+
 Available starting in the 3.27 microversion.
 
 Response codes
@@ -54,6 +68,7 @@ Response codes
 
    - 400
    - 404
+   - 409
 
 
 Request

api-ref/source/v3/volumes-v3-volumes-actions.inc

@@ -337,6 +337,21 @@ Preconditions
 
 - Volume status must be ``in-use``.
 
+For security reasons (see bug `#2004555
+<https://bugs.launchpad.net/nova/+bug/2004555>`_), regardless of the policy
+defaults,  the Block Storage API rejects REST API calls manually made from
+users with a 409 status code if completing the request could pose a risk, which
+happens if all of these happen:
+
+- The request comes from a user
+- There's an instance uuid in provided attachment or in the volume's attachment
+- VM exists in Nova
+- Instance has the volume attached
+- Attached volume in instance is using the attachment
+
+Calls coming from other OpenStack services (like the Compute Service) are
+always accepted.
+
 Response codes
 --------------
 
@@ -344,6 +359,9 @@ Response codes
 
    - 202
 
+.. rest_status_code:: error ../status.yaml
+
+   - 409
 
 Request
 -------
@@ -415,6 +433,21 @@ perform this operation. Cloud providers can change these permissions
 through the ``volume_extension:volume_admin_actions:force_detach`` rule in
 the policy configuration file.
 
+For security reasons (see bug `#2004555
+<https://bugs.launchpad.net/nova/+bug/2004555>`_), regardless of the policy
+defaults,  the Block Storage API rejects REST API calls manually made from
+users with a 409 status code if completing the request could pose a risk, which
+happens if all of these happen:
+
+- The request comes from a user
+- There's an instance uuid in provided attachment or in the volume's attachment
+- VM exists in Nova
+- Instance has the volume attached
+- Attached volume in instance is using the attachment
+
+Calls coming from other OpenStack services (like the Compute Service) are
+always accepted.
+
 Response codes
 --------------
 
@@ -422,6 +455,9 @@ Response codes
 
    - 202
 
+.. rest_status_code:: error ../status.yaml
+
+   - 409
 
 Request
 -------
@@ -883,6 +919,22 @@ Preconditions
 
 - Volume status must be ``in-use``.
 
+For security reasons (see bug `#2004555
+<https://bugs.launchpad.net/nova/+bug/2004555>`_), regardless of the policy
+defaults,  the Block Storage API rejects REST API calls manually made from
+users with a 409 status code if completing the request could pose a risk, which
+happens if all of these happen:
+
+- The request comes from a user
+- There's an instance uuid in the volume's attachment
+- VM exists in Nova
+- Instance has the volume attached
+- Attached volume in instance is using the attachment
+
+Calls coming from other OpenStack services (like the Compute Service) are
+always accepted.
+
+
 Response codes
 --------------
 
@@ -890,6 +942,9 @@ Response codes
 
    - 202
 
+.. rest_status_code:: error ../status.yaml
+
+   - 409
 
 Request
 -------

cinder/compute/nova.py

@@ -133,6 +133,7 @@ def novaclient(context, privileged_user=False, timeout=None, api_version=None):
 
 class API(base.Base):
     """API for interacting with novaclient."""
+    NotFound = nova_exceptions.NotFound
 
     def __init__(self):
         self.message_api = message_api.API()
@@ -237,3 +238,9 @@ class API(base.Base):
                 resource_uuid=volume_id,
                 detail=message_field.Detail.REIMAGE_VOLUME_FAILED)
         return result
+
+    @staticmethod
+    def get_server_volume(context, server_id, volume_id):
+        # Use microversion that includes attachment_id
+        nova = novaclient(context, api_version='2.89')
+        return nova.volumes.get_server_volume(server_id, volume_id)

cinder/exception.py

@@ -1092,3 +1092,10 @@ class DriverInitiatorDataExists(Duplicate):
         "Driver initiator data for initiator '%(initiator)s' and backend "
         "'%(namespace)s' with key '%(key)s' already exists."
     )
+
+
+class ConflictNovaUsingAttachment(CinderException):
+    message = _("Detach volume from instance %(instance_id)s using the "
+                "Compute API")
+    code = 409
+    safe = True

cinder/tests/unit/api/contrib/test_admin_actions.py

@@ -1037,6 +1037,8 @@ class AdminActionsAttachDetachTest(BaseAdminTest):
         super(AdminActionsAttachDetachTest, self).setUp()
         # start service to handle rpc messages for attach requests
         self.svc = self.start_service('volume', host='test')
+        self.mock_deletion_allowed = self.mock_object(
+            volume_api.API, 'attachment_deletion_allowed', return_value=None)
 
     def tearDown(self):
         self.svc.stop()
@@ -1092,6 +1094,16 @@ class AdminActionsAttachDetachTest(BaseAdminTest):
         admin_metadata = volume.admin_metadata
         self.assertEqual(1, len(admin_metadata))
         self.assertEqual('False', admin_metadata['readonly'])
+        # One call is for the terminate_connection and the other is for the
+        # detach
+        self.assertEqual(2, self.mock_deletion_allowed.call_count)
+        self.mock_deletion_allowed.assert_has_calls(
+            [mock.call(self.ctx, None, mock.ANY),
+             mock.call(self.ctx, attachment['id'], mock.ANY)])
+        for i in (0, 1):
+            self.assertIsInstance(
+                self.mock_deletion_allowed.call_args_list[i][0][2],
+                objects.Volume)
 
     def test_force_detach_host_attached_volume(self):
         # current status is available
@@ -1143,6 +1155,16 @@ class AdminActionsAttachDetachTest(BaseAdminTest):
         admin_metadata = volume['admin_metadata']
         self.assertEqual(1, len(admin_metadata))
         self.assertEqual('False', admin_metadata['readonly'])
+        # One call is for the terminate_connection and the other is for the
+        # detach
+        self.assertEqual(2, self.mock_deletion_allowed.call_count)
+        self.mock_deletion_allowed.assert_has_calls(
+            [mock.call(self.ctx, None, mock.ANY),
+             mock.call(self.ctx, attachment['id'], mock.ANY)])
+        for i in (0, 1):
+            self.assertIsInstance(
+                self.mock_deletion_allowed.call_args_list[i][0][2],
+                objects.Volume)
 
     def test_volume_force_detach_raises_remote_error(self):
         # current status is available
@@ -1186,6 +1208,10 @@ class AdminActionsAttachDetachTest(BaseAdminTest):
             resp = req.get_response(app())
             self.assertEqual(HTTPStatus.BAD_REQUEST, resp.status_int)
 
+        self.mock_deletion_allowed.assert_called_once_with(
+            self.ctx, None, volume)
+        self.mock_deletion_allowed.reset_mock()
+
         # test for VolumeBackendAPIException
         volume_remote_error = (
             messaging.RemoteError(exc_type='VolumeBackendAPIException'))
@@ -1205,6 +1231,8 @@ class AdminActionsAttachDetachTest(BaseAdminTest):
             self.assertRaises(messaging.RemoteError,
                               req.get_response,
                               app())
+        self.mock_deletion_allowed.assert_called_once_with(
+            self.ctx, None, volume)
 
     def test_volume_force_detach_raises_db_error(self):
         # In case of DB error 500 error code is returned to user
@@ -1250,6 +1278,8 @@ class AdminActionsAttachDetachTest(BaseAdminTest):
             self.assertRaises(messaging.RemoteError,
                               req.get_response,
                               app())
+        self.mock_deletion_allowed.assert_called_once_with(
+            self.ctx, None, volume)
 
     def test_volume_force_detach_missing_connector(self):
         # current status is available
@@ -1290,6 +1320,8 @@ class AdminActionsAttachDetachTest(BaseAdminTest):
             # make request
             resp = req.get_response(app())
             self.assertEqual(HTTPStatus.ACCEPTED, resp.status_int)
+        self.mock_deletion_allowed.assert_called_once_with(
+            self.ctx, None, volume)
 
     def test_attach_in_used_volume_by_instance(self):
         """Test that attaching to an in-use volume fails."""

cinder/tests/unit/api/v3/test_attachments.py

@@ -159,6 +159,8 @@ class AttachmentsAPITestCase(test.TestCase):
     @ddt.data('reserved', 'attached')
     @mock.patch.object(volume_rpcapi.VolumeAPI, 'attachment_delete')
     def test_delete_attachment(self, status, mock_delete):
+        self.patch('cinder.volume.api.API.attachment_deletion_allowed',
+                   return_value=None)
         volume1 = self._create_volume(display_name='fake_volume_1',
                                       project_id=fake.PROJECT_ID)
         attachment = self._create_attachment(

cinder/tests/unit/attachments/test_attachments_api.py

@@ -12,12 +12,14 @@
 
 from unittest import mock
 
+from cinder.compute import nova
 from cinder import context
 from cinder import db
 from cinder import exception
 from cinder import objects
 from cinder.tests.unit.api.v2 import fakes as v2_fakes
 from cinder.tests.unit import fake_constants as fake
+from cinder.tests.unit import fake_volume
 from cinder.tests.unit import test
 from cinder.tests.unit import utils as tests_utils
 from cinder.volume import api as volume_api
@@ -78,10 +80,13 @@ class AttachmentManagerTestCase(test.TestCase):
                                                             attachment.id)
         self.assertEqual(connection_info, new_attachment.connection_info)
 
+    @mock.patch.object(volume_api.API, 'attachment_deletion_allowed')
     @mock.patch('cinder.volume.rpcapi.VolumeAPI.attachment_delete')
     def test_attachment_delete_reserved(self,
-                                        mock_rpc_attachment_delete):
+                                        mock_rpc_attachment_delete,
+                                        mock_allowed):
         """Test attachment_delete with reserved."""
+        mock_allowed.return_value = None
         volume_params = {'status': 'available'}
 
         vref = tests_utils.create_volume(self.context, **volume_params)
@@ -94,18 +99,22 @@ class AttachmentManagerTestCase(test.TestCase):
         self.assertEqual(vref.id, aref.volume_id)
         self.volume_api.attachment_delete(self.context,
                                           aobj)
+        mock_allowed.assert_called_once_with(self.context, aobj)
 
         # Since it's just reserved and never finalized, we should never make an
         # rpc call
         mock_rpc_attachment_delete.assert_not_called()
 
+    @mock.patch.object(volume_api.API, 'attachment_deletion_allowed')
     @mock.patch('cinder.volume.rpcapi.VolumeAPI.attachment_delete')
     @mock.patch('cinder.volume.rpcapi.VolumeAPI.attachment_update')
     def test_attachment_create_update_and_delete(
             self,
             mock_rpc_attachment_update,
-            mock_rpc_attachment_delete):
+            mock_rpc_attachment_delete,
+            mock_allowed):
         """Test attachment_delete."""
+        mock_allowed.return_value = None
         volume_params = {'status': 'available'}
         connection_info = {'fake_key': 'fake_value',
                            'fake_key2': ['fake_value1', 'fake_value2']}
@@ -142,6 +151,7 @@ class AttachmentManagerTestCase(test.TestCase):
         self.volume_api.attachment_delete(self.context,
                                           aref)
 
+        mock_allowed.assert_called_once_with(self.context, aref)
         mock_rpc_attachment_delete.assert_called_once_with(self.context,
                                                            aref.id,
                                                            mock.ANY)
@@ -173,10 +183,13 @@ class AttachmentManagerTestCase(test.TestCase):
                                         vref.id)
         self.assertEqual(2, len(vref.volume_attachment))
 
+    @mock.patch.object(volume_api.API, 'attachment_deletion_allowed')
     @mock.patch('cinder.volume.rpcapi.VolumeAPI.attachment_update')
     def test_attachment_create_reserve_delete(
             self,
-            mock_rpc_attachment_update):
+            mock_rpc_attachment_update,
+            mock_allowed):
+        mock_allowed.return_value = None
         volume_params = {'status': 'available'}
         connector = {
             "initiator": "iqn.1993-08.org.debian:01:cad181614cec",
@@ -211,12 +224,15 @@ class AttachmentManagerTestCase(test.TestCase):
         # attachments reserve
         self.volume_api.attachment_delete(self.context,
                                           aref)
+        mock_allowed.assert_called_once_with(self.context, aref)
         vref = objects.Volume.get_by_id(self.context,
                                         vref.id)
         self.assertEqual('reserved', vref.status)
 
-    def test_reserve_reserve_delete(self):
+    @mock.patch.object(volume_api.API, 'attachment_deletion_allowed')
+    def test_reserve_reserve_delete(self, mock_allowed):
         """Test that we keep reserved status across multiple reserves."""
+        mock_allowed.return_value = None
         volume_params = {'status': 'available'}
 
         vref = tests_utils.create_volume(self.context, **volume_params)
@@ -235,6 +251,7 @@ class AttachmentManagerTestCase(test.TestCase):
         self.assertEqual('reserved', vref.status)
         self.volume_api.attachment_delete(self.context,
                                           aref)
+        mock_allowed.assert_called_once_with(self.context, aref)
         vref = objects.Volume.get_by_id(self.context,
                                         vref.id)
         self.assertEqual('reserved', vref.status)
@@ -344,3 +361,169 @@ class AttachmentManagerTestCase(test.TestCase):
                           self.context,
                           vref,
                           fake.UUID1)
+
+    def _get_attachment(self, with_instance_id=True):
+        volume = fake_volume.fake_volume_obj(self.context, id=fake.VOLUME_ID)
+        volume.volume_attachment = objects.VolumeAttachmentList()
+        attachment = fake_volume.volume_attachment_ovo(
+            self.context,
+            volume_id=fake.VOLUME_ID,
+            instance_uuid=fake.INSTANCE_ID if with_instance_id else None,
+            connection_info='{"a": 1}')
+        attachment.volume = volume
+        return attachment
+
+    @mock.patch('cinder.compute.nova.API.get_server_volume')
+    def test_attachment_deletion_allowed_service_call(self, mock_get_server):
+        """Service calls are never redirected."""
+        self.context.service_roles = ['reader', 'service']
+        attachment = self._get_attachment()
+        self.volume_api.attachment_deletion_allowed(self.context, attachment)
+        mock_get_server.assert_not_called()
+
+    @mock.patch('cinder.compute.nova.API.get_server_volume')
+    def test_attachment_deletion_allowed_service_call_different_service_name(
+            self, mock_get_server):
+        """Service calls are never redirected and role can be different.
+
+        In this test we support 2 different service roles, the standard service
+        and a custom one called captain_awesome, and passing the custom one
+        works as expected.
+        """
+        self.override_config('service_token_roles',
+                             ['service', 'captain_awesome'],
+                             group='keystone_authtoken')
+
+        self.context.service_roles = ['reader', 'captain_awesome']
+        attachment = self._get_attachment()
+        self.volume_api.attachment_deletion_allowed(self.context, attachment)
+        mock_get_server.assert_not_called()
+
+    @mock.patch('cinder.compute.nova.API.get_server_volume')
+    def test_attachment_deletion_allowed_no_instance(self, mock_get_server):
+        """Attachments with no instance id are never redirected."""
+        attachment = self._get_attachment(with_instance_id=False)
+        self.volume_api.attachment_deletion_allowed(self.context, attachment)
+        mock_get_server.assert_not_called()
+
+    @mock.patch('cinder.compute.nova.API.get_server_volume')
+    def test_attachment_deletion_allowed_no_conn_info(self, mock_get_server):
+        """Attachments with no connection information are never redirected."""
+        attachment = self._get_attachment(with_instance_id=False)
+        attachment.connection_info = None
+        self.volume_api.attachment_deletion_allowed(self.context, attachment)
+
+        mock_get_server.assert_not_called()
+
+    def test_attachment_deletion_allowed_no_attachment(self):
+        """For users don't allow operation with no attachment reference."""
+        self.assertRaises(exception.ConflictNovaUsingAttachment,
+                          self.volume_api.attachment_deletion_allowed,
+                          self.context, None)
+
+    @mock.patch('cinder.objects.VolumeAttachment.get_by_id',
+                side_effect=exception.VolumeAttachmentNotFound())
+    def test_attachment_deletion_allowed_attachment_id_not_found(self,
+                                                                 mock_get):
+        """For users don't allow if attachment cannot be found."""
+        attachment = self._get_attachment(with_instance_id=False)
+        attachment.connection_info = None
+        self.assertRaises(exception.ConflictNovaUsingAttachment,
+                          self.volume_api.attachment_deletion_allowed,
+                          self.context, fake.ATTACHMENT_ID)
+        mock_get.assert_called_once_with(self.context, fake.ATTACHMENT_ID)
+
+    def test_attachment_deletion_allowed_volume_no_attachments(self):
+        """For users allow if volume has no attachments."""
+        volume = tests_utils.create_volume(self.context)
+        self.volume_api.attachment_deletion_allowed(self.context, None, volume)
+
+    def test_attachment_deletion_allowed_multiple_attachment(self):
+        """For users don't allow if volume has multiple attachments."""
+        attachment = self._get_attachment()
+        volume = attachment.volume
+        volume.volume_attachment = objects.VolumeAttachmentList(
+            objects=[attachment, attachment])
+        self.assertRaises(exception.ConflictNovaUsingAttachment,
+                          self.volume_api.attachment_deletion_allowed,
+                          self.context, None, volume)
+
+    @mock.patch('cinder.compute.nova.API.get_server_volume')
+    def test_attachment_deletion_allowed_vm_not_found(self, mock_get_server):
+        """Don't reject if instance doesn't exist"""
+        mock_get_server.side_effect = nova.API.NotFound(404)
+        attachment = self._get_attachment()
+        self.volume_api.attachment_deletion_allowed(self.context, attachment)
+
+        mock_get_server.assert_called_once_with(self.context, fake.INSTANCE_ID,
+                                                fake.VOLUME_ID)
+
+    @mock.patch('cinder.compute.nova.API.get_server_volume')
+    def test_attachment_deletion_allowed_attachment_from_volume(
+            self, mock_get_server):
+        """Don't reject if instance doesn't exist"""
+        mock_get_server.side_effect = nova.API.NotFound(404)
+        attachment = self._get_attachment()
+        volume = attachment.volume
+        volume.volume_attachment = objects.VolumeAttachmentList(
+            objects=[attachment])
+        self.volume_api.attachment_deletion_allowed(self.context, None, volume)
+
+        mock_get_server.assert_called_once_with(self.context, fake.INSTANCE_ID,
+                                                volume.id)
+
+    @mock.patch('cinder.objects.VolumeAttachment.get_by_id')
+    def test_attachment_deletion_allowed_mismatched_volume_and_attach_id(
+            self, mock_get_attatchment):
+        """Reject if volume and attachment don't match."""
+        attachment = self._get_attachment()
+        volume = attachment.volume
+        volume.volume_attachment = objects.VolumeAttachmentList(
+            objects=[attachment])
+        attachment2 = self._get_attachment()
+        attachment2.volume_id = attachment.volume.id = fake.VOLUME2_ID
+        self.assertRaises(exception.InvalidInput,
+                          self.volume_api.attachment_deletion_allowed,
+                          self.context, attachment2.id, volume)
+        mock_get_attatchment.assert_called_once_with(self.context,
+                                                     attachment2.id)
+
+    @mock.patch('cinder.objects.VolumeAttachment.get_by_id')
+    @mock.patch('cinder.compute.nova.API.get_server_volume')
+    def test_attachment_deletion_allowed_not_found_attachment_id(
+            self, mock_get_server, mock_get_attachment):
+        """Don't reject if instance doesn't exist"""
+        mock_get_server.side_effect = nova.API.NotFound(404)
+        mock_get_attachment.return_value = self._get_attachment()
+
+        self.volume_api.attachment_deletion_allowed(self.context,
+                                                    fake.ATTACHMENT_ID)
+
+        mock_get_attachment.assert_called_once_with(self.context,
+                                                    fake.ATTACHMENT_ID)
+
+        mock_get_server.assert_called_once_with(self.context, fake.INSTANCE_ID,
+                                                fake.VOLUME_ID)
+
+    @mock.patch('cinder.compute.nova.API.get_server_volume')
+    def test_attachment_deletion_allowed_mismatch_id(self, mock_get_server):
+        """Don't reject if attachment id on nova doesn't match"""
+        mock_get_server.return_value.attachment_id = fake.ATTACHMENT2_ID
+        attachment = self._get_attachment()
+        self.volume_api.attachment_deletion_allowed(self.context, attachment)
+
+        mock_get_server.assert_called_once_with(self.context, fake.INSTANCE_ID,
+                                                fake.VOLUME_ID)
+
+    @mock.patch('cinder.compute.nova.API.get_server_volume')
+    def test_attachment_deletion_allowed_user_call_fails(self,
+                                                         mock_get_server):
+        """Fail user calls"""
+        attachment = self._get_attachment()
+        mock_get_server.return_value.attachment_id = attachment.id
+        self.assertRaises(exception.ConflictNovaUsingAttachment,
+                          self.volume_api.attachment_deletion_allowed,
+                          self.context, attachment)
+
+        mock_get_server.assert_called_once_with(self.context, fake.INSTANCE_ID,
+                                                fake.VOLUME_ID)

cinder/tests/unit/policies/test_attachments.py

@@ -62,6 +62,9 @@ class AttachmentsPolicyTest(base.BasePolicyTest):
 
         self.api_path = '/v3/%s/attachments' % (self.project_id)
         self.api_version = mv.NEW_ATTACH
+        self.mock_is_service = self.patch(
+            'cinder.volume.api.API.is_service_request',
+            return_value=True)
 
     def _initialize_connection(self, volume, connector):
         return {'data': connector}

cinder/tests/unit/policies/test_volume_actions.py

@@ -89,6 +89,9 @@ class VolumeActionsPolicyTest(base.BasePolicyTest):
             self._initialize_connection)
         self.api_path = '/v3/%s/volumes' % (self.project_id)
         self.api_version = mv.BASE_VERSION
+        self.mock_is_service = self.patch(
+            'cinder.volume.api.API.is_service_request',
+            return_value=True)
 
     def _initialize_connection(self, volume, connector):
         return {'data': connector}
@@ -946,6 +949,7 @@ class VolumeProtectionTests(test_base.CinderPolicyTests):
         self.assertEqual(HTTPStatus.ACCEPTED, response.status_int)
 
         body = {"os-detach": {}}
+        # Detach for user call succeeds because the volume has no attachments
         response = self._get_request_response(admin_context, path, 'POST',
                                               body=body)
         self.assertEqual(HTTPStatus.ACCEPTED, response.status_int)
@@ -966,6 +970,7 @@ class VolumeProtectionTests(test_base.CinderPolicyTests):
                                               body=body)
         self.assertEqual(HTTPStatus.ACCEPTED, response.status_int)
 
+        # Succeeds for a user call because there are no attachments
         body = {"os-detach": {}}
         response = self._get_request_response(user_context, path, 'POST',
                                               body=body)
@@ -1062,6 +1067,7 @@ class VolumeProtectionTests(test_base.CinderPolicyTests):
                        'terminate_connection')
     def test_admin_can_initialize_terminate_conn(self, mock_t, mock_i):
         admin_context = self.admin_context
+        admin_context.service_roles = ['service']
 
         volume = self._create_fake_volume(admin_context)
         path = '/v3/%(project_id)s/volumes/%(volume_id)s/action' % {
@@ -1084,6 +1090,7 @@ class VolumeProtectionTests(test_base.CinderPolicyTests):
                        'terminate_connection')
     def test_owner_can_initialize_terminate_conn(self, mock_t, mock_i):
         user_context = self.user_context
+        user_context.service_roles = ['service']
 
         volume = self._create_fake_volume(user_context)
         path = '/v3/%(project_id)s/volumes/%(volume_id)s/action' % {

cinder/tests/unit/volume/test_connection.py

@@ -1334,7 +1334,8 @@ class VolumeAttachDetachTestCase(base.BaseVolumeTestCase):
                           self.context,
                           volume, None, None, None, None)
 
-    def test_volume_detach_in_maintenance(self):
+    @mock.patch('cinder.volume.api.API.attachment_deletion_allowed')
+    def test_volume_detach_in_maintenance(self, mock_attachment_deletion):
         """Test detach the volume in maintenance."""
         test_meta1 = {'fake_key1': 'fake_value1', 'fake_key2': 'fake_value2'}
         volume = tests_utils.create_volume(self.context, metadata=test_meta1,
@@ -1345,3 +1346,5 @@ class VolumeAttachDetachTestCase(base.BaseVolumeTestCase):
                           volume_api.detach,
                           self.context,
                           volume, None)
+        mock_attachment_deletion.assert_called_once_with(self.context,
+                                                         None, volume)

cinder/volume/api.py

@@ -34,6 +34,7 @@ import webob
 
 from cinder.api import common
 from cinder.common import constants
+from cinder import compute
 from cinder import context
 from cinder import coordination
 from cinder import db
@@ -862,11 +863,14 @@ class API(base.Base):
                attachment_id: str) -> None:
         context.authorize(vol_action_policy.DETACH_POLICY,
                           target_obj=volume)
+        self.attachment_deletion_allowed(context, attachment_id, volume)
+
         if volume['status'] == 'maintenance':
             LOG.info('Unable to detach volume, '
                      'because it is in maintenance.', resource=volume)
             msg = _("The volume cannot be detached in maintenance mode.")
             raise exception.InvalidVolume(reason=msg)
+
         detach_results = self.volume_rpcapi.detach_volume(context, volume,
                                                           attachment_id)
         LOG.info("Detach volume completed successfully.",
@@ -893,6 +897,19 @@ class API(base.Base):
                  resource=volume)
         return init_results
 
+    @staticmethod
+    def is_service_request(ctxt: 'context.RequestContext') -> bool:
+        """Check if a request is coming from a service
+
+        A request is coming from a service if it has a service token and the
+        service user has one of the roles configured in the
+        `service_token_roles` configuration option in the
+        `[keystone_authtoken]` section (defaults to `service`).
+        """
+        roles = ctxt.service_roles
+        service_roles = set(CONF.keystone_authtoken.service_token_roles)
+        return bool(roles and service_roles.intersection(roles))
+
     def terminate_connection(self,
                              context: context.RequestContext,
                              volume: objects.Volume,
@@ -900,6 +917,8 @@ class API(base.Base):
                              force: bool = False) -> None:
         context.authorize(vol_action_policy.TERMINATE_POLICY,
                           target_obj=volume)
+        self.attachment_deletion_allowed(context, None, volume)
+
         self.volume_rpcapi.terminate_connection(context,
                                                 volume,
                                                 connector,
@@ -2521,11 +2540,90 @@ class API(base.Base):
         attachment_ref.save()
         return attachment_ref
 
+    def attachment_deletion_allowed(self,
+                                    ctxt: context.RequestContext,
+                                    attachment_or_attachment_id,
+                                    volume=None):
+        """Check if deleting an attachment is allowed (Bug #2004555)
+
+        Allowed is based on the REST API policy, the status of the attachment,
+        where it is used, and who is making the request.
+
+        Deleting an attachment on the Cinder side while leaving the volume
+        connected to the nova host results in leftover devices that can lead to
+        data leaks/corruption.
+
+        OS-Brick may have code to detect it, but in some cases it is detected
+        after it has already been exposed, so it's better to prevent users from
+        being able to intentionally triggering the issue.
+        """
+        # It's ok to delete an attachment if the request comes from a service
+        if self.is_service_request(ctxt):
+            return
+
+        if not attachment_or_attachment_id and volume:
+            if not volume.volume_attachment:
+                return
+            if len(volume.volume_attachment) == 1:
+                attachment_or_attachment_id = volume.volume_attachment[0]
+
+        if isinstance(attachment_or_attachment_id, str):
+            try:
+                attachment = objects.VolumeAttachment.get_by_id(
+                    ctxt, attachment_or_attachment_id)
+            except exception.VolumeAttachmentNotFound:
+                attachment = None
+        else:
+            attachment = attachment_or_attachment_id
+
+        if attachment:
+            if volume:
+                if volume.id != attachment.volume_id:
+                    raise exception.InvalidInput(
+                        reason='Mismatched volume and attachment')
+
+            server_id = attachment.instance_uuid
+            # It's ok to delete if it's not connected to a vm.
+            if not server_id or not attachment.connection_info:
+                return
+
+            volume = volume or attachment.volume
+            nova = compute.API()
+            LOG.info('Attachment connected to vm %s, checking data on nova',
+                     server_id)
+            # If nova is down the client raises 503 and we report that
+            try:
+                nova_volume = nova.get_server_volume(ctxt, server_id,
+                                                     volume.id)
+            except nova.NotFound:
+                LOG.warning('Instance or volume not found on Nova, deleting '
+                            'attachment locally, which may leave leftover '
+                            'devices on Nova compute')
+                return
+
+            if nova_volume.attachment_id != attachment.id:
+                LOG.warning('Mismatch! Nova has different attachment id (%s) '
+                            'for the volume, deleting attachment locally. '
+                            'May leave leftover devices in a compute node',
+                            nova_volume.attachment_id)
+                return
+        else:
+            server_id = ''
+
+        LOG.error('Detected user call to delete in-use attachment. Call must '
+                  'come from the nova service and nova must be configured to '
+                  'send the service token. Bug #2004555')
+        raise exception.ConflictNovaUsingAttachment(instance_id=server_id)
+
     def attachment_delete(self,
                           ctxt: context.RequestContext,
                           attachment) -> objects.VolumeAttachmentList:
+        # Check if policy allows user to delete attachment
         ctxt.authorize(attachment_policy.DELETE_POLICY,
                        target_obj=attachment)
+
+        self.attachment_deletion_allowed(ctxt, attachment)
+
         volume = attachment.volume
 
         if attachment.attach_status == fields.VolumeAttachStatus.RESERVED:

doc/source/configuration/block-storage/service-token.rst

@@ -1,6 +1,6 @@
-=========================================================
+====================
-Using service tokens to prevent long-running job failures
+Using service tokens
-=========================================================
+====================
 
 When a user initiates a request whose processing involves multiple services
 (for example, a boot-from-volume request to the Compute Service will require
@@ -8,20 +8,32 @@ processing by the Block Storage Service, and may require processing by the
 Image Service), the user's token is handed from service to service.  This
 ensures that the requestor is tracked correctly for audit purposes and also
 guarantees that the requestor has the appropriate permissions to do what needs
-to be done by the other services.  If the chain of operations takes a long
+to be done by the other services.
-time, however, the user's token may expire before the action is completed,
-leading to the failure of the user's original request.
 
-One way to deal with this is to set a long token life in Keystone, and this may
+There are several instances where we want to differentiate between a request
-be what you are currently doing.  But this can be problematic for installations
+coming from the user to one coming from another OpenStack service on behalf of
-whose security policies prefer short user token lives.  Beginning with the
+the user:
-Queens release, an alternative solution is available.  You have the ability to
+
-configure some services (particularly Nova and Cinder) to send a "service
+- **For security reasons** There are some operations in the Block Storage
-token" along with the user's token.  When properly configured, the Identity
+  service, required for normal operations, that could be exploited by a
-Service will validate an expired user token *when it is accompanied by a valid
+  malicious user to gain access to resources belonging to other users.  By
-service token*.  Thus if the user's token expires somewhere during a long
+  differentiating when the request comes directly from a user and when from
-running chain of operations among various OpenStack services, the operations
+  another OpenStack service the Cinder service can protect the deployment.
-can continue.
+
+- To prevent long-running job failures: If the chain of operations takes a long
+  time, the user's token may expire before the action is completed, leading to
+  the failure of the user's original request.
+
+  One way to deal with this is to set a long token life in Keystone, and this
+  may be what you are currently doing.  But this can be problematic for
+  installations whose security policies prefer short user token lives.
+  Beginning with the Queens release, an alternative solution is available.  You
+  have the ability to configure some services (particularly Nova and Cinder) to
+  send a "service token" along with the user's token.  When properly
+  configured, the Identity Service will validate an expired user token *when it
+  is accompanied by a valid service token*.  Thus if the user's token expires
+  somewhere during a long running chain of operations among various OpenStack
+  services, the operations can continue.
 
 .. note::
    There's nothing special about a service token.  It's a regular token

doc/source/configuration/index.rst

@@ -6,6 +6,7 @@ Cinder Service Configuration
    :maxdepth: 1
 
    block-storage/block-storage-overview.rst
+   block-storage/service-token.rst
    block-storage/volume-drivers.rst
    block-storage/backup-drivers.rst
    block-storage/schedulers.rst
@@ -15,10 +16,16 @@ Cinder Service Configuration
    block-storage/policy-config-HOWTO.rst
    block-storage/fc-zoning.rst
    block-storage/volume-encryption.rst
-   block-storage/service-token.rst
    block-storage/config-options.rst
    block-storage/samples/index.rst
 
+.. warning::
+
+   For security reasons **Service Tokens must to be configured** in OpenStack
+   for Cinder to operate securely.  Pay close attention to the :doc:`specific
+   section describing it: <block-storage/service-token>`. See
+   https://bugs.launchpad.net/nova/+bug/2004555 for details.
+
 .. note::
 
    The examples of common configurations for shared

doc/source/install/index.rst

@@ -35,6 +35,13 @@ Adding Cinder to your OpenStack Environment
 
 The following links describe how to install the Cinder Block Storage Service:
 
+.. warning::
+
+   For security reasons **Service Tokens must to be configured** in OpenStack
+   for Cinder to operate securely.  Pay close attention to the :doc:`specific
+   section describing it: <../configuration/block-storage/service-token>`. See
+   https://bugs.launchpad.net/nova/+bug/2004555 for details.
+
 .. toctree::
 
    get-started-block-storage

releasenotes/notes/redirect-detach-nova-4b7b7902d7d182e0.yaml

@@ -0,0 +1,43 @@
+---
+critical:
+  - |
+    Detaching volumes will fail if Nova is not `configured to send service
+    tokens <https://docs.openstack.org/cinder/latest/configuration/block-storage/service-token.html>`_,
+    please read the upgrade section for more information. (`Bug #2004555
+    <https://bugs.launchpad.net/cinder/+bug/2004555>`_).
+upgrade:
+  - |
+    Nova must be `configured to send service tokens
+    <https://docs.openstack.org/cinder/latest/configuration/block-storage/service-token.html>`_
+    **and** cinder must be configured to recognize at least one of the roles
+    that the nova service user has been assigned in keystone. By default,
+    cinder will recognize the ``service`` role, so if the nova service user
+    is assigned a differently named role in your cloud, you must adjust your
+    cinder configuration file (``service_token_roles`` configuration option
+    in the ``keystone_authtoken`` section). If nova and cinder are not
+    configured correctly in this regard, detaching volumes will no longer
+    work (`Bug #2004555 <https://bugs.launchpad.net/cinder/+bug/2004555>`_).
+security:
+  - |
+    As part of the fix for `Bug #2004555
+    <https://bugs.launchpad.net/cinder/+bug/2004555>`_, cinder now rejects
+    user attachment delete requests for attachments that are being used by nova
+    instances to ensure that no leftover devices are produced on the compute
+    nodes which could be used to access another project's volumes.  Terminate
+    connection, detach, and force detach volume actions (calls that are not
+    usually made by users directly) are, in most cases, not allowed for users.
+fixes:
+  - |
+    `Bug #2004555 <https://bugs.launchpad.net/cinder/+bug/2004555>`_: Fixed
+    issue where a user manually deleting an attachment, calling terminate
+    connection, detach, or force detach, for a volume that is still used by a
+    nova instance resulted in leftover devices on the compute node. These
+    operations will now fail when it is believed to be a problem.
+issues:
+  - |
+    For security reasons (`Bug #2004555
+    <https://bugs.launchpad.net/cinder/+bug/2004555>`_) manually deleting an
+    attachment, manually doing the ``os-terminate_connection``, ``os-detach``
+    or ``os-force_detach`` actions will no longer be allowed in most cases
+    unless the request is coming from another OpenStack service on behalf of a
+    user.