Do not propagate profile changes of shadow-banned users into rooms

changelog.d/8157.feature

@@ -0,0 +1 @@
+Add support for shadow-banning users (ignoring any message send requests).

synapse/handlers/profile.py

@@ -14,6 +14,7 @@
 # limitations under the License.
 
 import logging
+import random
 
 from synapse.api.errors import (
     AuthError,
@@ -213,8 +214,14 @@ async def get_avatar_url(self, target_user):
     async def set_avatar_url(
         self, target_user, requester, new_avatar_url, by_admin=False
     ):
-        """target_user is the user whose avatar_url is to be changed;
-        auth_user is the user attempting to make this change."""
+        """Set a new avatar URL for a user.
+
+        Args:
+            target_user (UserID): the user whose avatar URL is to be changed.
+            requester (Requester): The user attempting to make this change.
+            new_avatar_url (str): The avatar URL to give this user.
+            by_admin (bool): Whether this change was made by an administrator.
+        """
         if not self.hs.is_mine(target_user):
             raise SynapseError(400, "User is not hosted on this homeserver")
 
@@ -278,6 +285,12 @@ async def _update_join_states(self, requester, target_user):
 
         await self.ratelimit(requester)
 
+        # Do not actually update the room state for shadow-banned users.
+        if requester.shadow_banned:
+            # We randomly sleep a bit just to annoy the requester.
+            await self.clock.sleep(random.randint(1, 10))
+            return
+
         room_ids = await self.store.get_rooms_for_user(target_user.to_string())
 
         for room_id in room_ids:

synapse/handlers/room_member.py

@@ -380,7 +380,7 @@ async def _update_membership(
             # later on.
             content = dict(content)
 
-        if not self.allow_per_room_profiles:
+        if not self.allow_per_room_profiles or requester.shadow_banned:
             # Strip profile data, knowing that new profile data will be added to the
             # event's content in event_creation_handler.create_event() using the target's
             # global profile.

tests/rest/client/test_shadow_banned.py

@@ -0,0 +1,272 @@
+#  Copyright 2020 The Matrix.org Foundation C.I.C.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+
+from mock import Mock, patch
+
+import synapse.rest.admin
+from synapse.api.constants import EventTypes
+from synapse.rest.client.v1 import directory, login, profile, room
+from synapse.rest.client.v2_alpha import room_upgrade_rest_servlet
+
+from tests import unittest
+
+
+class _ShadowBannedBase(unittest.HomeserverTestCase):
+    def prepare(self, reactor, clock, homeserver):
+        # Create two users, one of which is shadow-banned.
+        self.banned_user_id = self.register_user("banned", "test")
+        self.banned_access_token = self.login("banned", "test")
+
+        self.store = self.hs.get_datastore()
+
+        self.get_success(
+            self.store.db_pool.simple_update(
+                table="users",
+                keyvalues={"name": self.banned_user_id},
+                updatevalues={"shadow_banned": True},
+                desc="shadow_ban",
+            )
+        )
+
+        self.other_user_id = self.register_user("otheruser", "pass")
+        self.other_access_token = self.login("otheruser", "pass")
+
+
+# To avoid the tests timing out don't add a delay to "annoy the requester".
+@patch("random.randint", new=lambda a, b: 0)
+class RoomTestCase(_ShadowBannedBase):
+    servlets = [
+        synapse.rest.admin.register_servlets_for_client_rest_resource,
+        directory.register_servlets,
+        login.register_servlets,
+        room.register_servlets,
+        room_upgrade_rest_servlet.register_servlets,
+    ]
+
+    def test_invite(self):
+        """Invites from shadow-banned users don't actually get sent."""
+
+        # The create works fine.
+        room_id = self.helper.create_room_as(
+            self.banned_user_id, tok=self.banned_access_token
+        )
+
+        # Inviting the user completes successfully.
+        self.helper.invite(
+            room=room_id,
+            src=self.banned_user_id,
+            tok=self.banned_access_token,
+            targ=self.other_user_id,
+        )
+
+        # But the user wasn't actually invited.
+        invited_rooms = self.get_success(
+            self.store.get_invited_rooms_for_local_user(self.other_user_id)
+        )
+        self.assertEqual(invited_rooms, [])
+
+    def test_invite_3pid(self):
+        """Ensure that a 3PID invite does not attempt to contact the identity server."""
+        identity_handler = self.hs.get_handlers().identity_handler
+        identity_handler.lookup_3pid = Mock(
+            side_effect=AssertionError("This should not get called")
+        )
+
+        # The create works fine.
+        room_id = self.helper.create_room_as(
+            self.banned_user_id, tok=self.banned_access_token
+        )
+
+        # Inviting the user completes successfully.
+        request, channel = self.make_request(
+            "POST",
+            "/rooms/%s/invite" % (room_id,),
+            {"id_server": "test", "medium": "email", "address": "test@test.test"},
+            access_token=self.banned_access_token,
+        )
+        self.render(request)
+        self.assertEquals(200, channel.code, channel.result)
+
+        # This should have raised an error earlier, but double check this wasn't called.
+        identity_handler.lookup_3pid.assert_not_called()
+
+    def test_create_room(self):
+        """Invitations during a room creation should be discarded, but the room still gets created."""
+        # The room creation is successful.
+        request, channel = self.make_request(
+            "POST",
+            "/_matrix/client/r0/createRoom",
+            {"visibility": "public", "invite": [self.other_user_id]},
+            access_token=self.banned_access_token,
+        )
+        self.render(request)
+        self.assertEquals(200, channel.code, channel.result)
+        room_id = channel.json_body["room_id"]
+
+        # But the user wasn't actually invited.
+        invited_rooms = self.get_success(
+            self.store.get_invited_rooms_for_local_user(self.other_user_id)
+        )
+        self.assertEqual(invited_rooms, [])
+
+        # Since a real room was created, the other user should be able to join it.
+        self.helper.join(room_id, self.other_user_id, tok=self.other_access_token)
+
+        # Both users should be in the room.
+        users = self.get_success(self.store.get_users_in_room(room_id))
+        self.assertCountEqual(users, ["@banned:test", "@otheruser:test"])
+
+    def test_message(self):
+        """Messages from shadow-banned users don't actually get sent."""
+
+        room_id = self.helper.create_room_as(
+            self.other_user_id, tok=self.other_access_token
+        )
+
+        # The user should be in the room.
+        self.helper.join(room_id, self.banned_user_id, tok=self.banned_access_token)
+
+        # Sending a message should complete successfully.
+        result = self.helper.send_event(
+            room_id=room_id,
+            type=EventTypes.Message,
+            content={"msgtype": "m.text", "body": "with right label"},
+            tok=self.banned_access_token,
+        )
+        self.assertIn("event_id", result)
+        event_id = result["event_id"]
+
+        latest_events = self.get_success(
+            self.store.get_latest_event_ids_in_room(room_id)
+        )
+        self.assertNotIn(event_id, latest_events)
+
+    def test_upgrade(self):
+        """A room upgrade should fail, but look like it succeeded."""
+
+        # The create works fine.
+        room_id = self.helper.create_room_as(
+            self.banned_user_id, tok=self.banned_access_token
+        )
+
+        request, channel = self.make_request(
+            "POST",
+            "/_matrix/client/r0/rooms/%s/upgrade" % (room_id,),
+            {"new_version": "6"},
+            access_token=self.banned_access_token,
+        )
+        self.render(request)
+        self.assertEquals(200, channel.code, channel.result)
+        # A new room_id should be returned.
+        self.assertIn("replacement_room", channel.json_body)
+
+        new_room_id = channel.json_body["replacement_room"]
+
+        # It doesn't really matter what API we use here, we just want to assert
+        # that the room doesn't exist.
+        summary = self.get_success(self.store.get_room_summary(new_room_id))
+        # The summary should be empty since the room doesn't exist.
+        self.assertEqual(summary, {})
+
+
+# To avoid the tests timing out don't add a delay to "annoy the requester".
+@patch("random.randint", new=lambda a, b: 0)
+class ProfileTestCase(_ShadowBannedBase):
+    servlets = [
+        synapse.rest.admin.register_servlets_for_client_rest_resource,
+        login.register_servlets,
+        profile.register_servlets,
+        room.register_servlets,
+    ]
+
+    def test_displayname(self):
+        """Profile changes should succeed, but don't end up in a room."""
+        original_display_name = "banned"
+        new_display_name = "new name"
+
+        # Join a room.
+        room_id = self.helper.create_room_as(
+            self.banned_user_id, tok=self.banned_access_token
+        )
+
+        # The update should succeed.
+        request, channel = self.make_request(
+            "PUT",
+            "/_matrix/client/r0/profile/%s/displayname" % (self.banned_user_id,),
+            {"displayname": new_display_name},
+            access_token=self.banned_access_token,
+        )
+        self.render(request)
+        self.assertEquals(200, channel.code, channel.result)
+        self.assertEqual(channel.json_body, {})
+
+        # The user's display name should be updated.
+        request, channel = self.make_request(
+            "GET", "/profile/%s/displayname" % (self.banned_user_id,)
+        )
+        self.render(request)
+        self.assertEqual(channel.code, 200, channel.result)
+        self.assertEqual(channel.json_body["displayname"], new_display_name)
+
+        # But the display name in the room should not be.
+        message_handler = self.hs.get_message_handler()
+        event = self.get_success(
+            message_handler.get_room_data(
+                self.banned_user_id,
+                room_id,
+                "m.room.member",
+                self.banned_user_id,
+                False,
+            )
+        )
+        self.assertEqual(
+            event.content, {"membership": "join", "displayname": original_display_name}
+        )
+
+    def test_room_displayname(self):
+        """Changes to state events for a room should be processed, but not end up in the room."""
+        original_display_name = "banned"
+        new_display_name = "new name"
+
+        # Join a room.
+        room_id = self.helper.create_room_as(
+            self.banned_user_id, tok=self.banned_access_token
+        )
+
+        # The update should succeed.
+        request, channel = self.make_request(
+            "PUT",
+            "/_matrix/client/r0/rooms/%s/state/m.room.member/%s"
+            % (room_id, self.banned_user_id),
+            {"membership": "join", "displayname": new_display_name},
+            access_token=self.banned_access_token,
+        )
+        self.render(request)
+        self.assertEquals(200, channel.code, channel.result)
+        self.assertIn("event_id", channel.json_body)
+
+        # The display name in the room should not be changed.
+        message_handler = self.hs.get_message_handler()
+        event = self.get_success(
+            message_handler.get_room_data(
+                self.banned_user_id,
+                room_id,
+                "m.room.member",
+                self.banned_user_id,
+                False,
+            )
+        )
+        self.assertEqual(
+            event.content, {"membership": "join", "displayname": original_display_name}
+        )