diff --git a/changelog.d/59.feature b/changelog.d/59.feature
new file mode 100644
index 0000000000..aa07f762d1
--- /dev/null
+++ b/changelog.d/59.feature
@@ -0,0 +1 @@
+Freeze a room when the last administrator in the room leaves.
\ No newline at end of file
diff --git a/synapse/third_party_rules/access_rules.py b/synapse/third_party_rules/access_rules.py
index a8b21048ec..2519e05ae0 100644
--- a/synapse/third_party_rules/access_rules.py
+++ b/synapse/third_party_rules/access_rules.py
@@ -13,6 +13,7 @@
# See the License for the specific language governing permissions and
# limitations under the License.
import email.utils
+import logging
from typing import Dict, List, Optional, Tuple
from twisted.internet import defer
@@ -22,7 +23,9 @@ from synapse.api.errors import SynapseError
from synapse.config._base import ConfigError
from synapse.events import EventBase
from synapse.module_api import ModuleApi
-from synapse.types import Requester, StateMap, get_domain_from_id
+from synapse.types import Requester, StateMap, UserID, get_domain_from_id
+
+logger = logging.getLogger(__name__)
ACCESS_RULES_TYPE = "im.vector.room.access_rules"
@@ -323,7 +326,7 @@ class RoomAccessRules(object):
)
if event.type == EventTypes.Member or event.type == EventTypes.ThirdPartyInvite:
- return self._on_membership_or_invite(event, rule, state_events)
+ return await self._on_membership_or_invite(event, rule, state_events)
if event.type == EventTypes.JoinRules:
return self._on_join_rule_change(event, rule)
@@ -420,7 +423,7 @@ class RoomAccessRules(object):
prev_rule == AccessRules.RESTRICTED and new_rule == AccessRules.UNRESTRICTED
)
- def _on_membership_or_invite(
+ async def _on_membership_or_invite(
self, event: EventBase, rule: str, state_events: StateMap[EventBase],
) -> bool:
"""Applies the correct rule for incoming m.room.member and
@@ -446,8 +449,154 @@ class RoomAccessRules(object):
# might want to change that in the future.
ret = self._on_membership_or_invite_restricted(event)
+ if event.type == "m.room.member":
+ # If this is an admin leaving, and they are the last admin in the room,
+ # raise the power levels of the room so that the room is 'frozen'.
+ #
+ # We have to freeze the room by puppeting an admin user, which we can
+ # only do for local users
+ if (
+ self._is_local_user(event.sender)
+ and event.membership == Membership.LEAVE
+ ):
+ await self._freeze_room_if_last_admin_is_leaving(event, state_events)
+
return ret
+ async def _freeze_room_if_last_admin_is_leaving(
+ self, event: EventBase, state_events: StateMap[EventBase]
+ ):
+ power_level_state_event = state_events.get(
+ (EventTypes.PowerLevels, "")
+ ) # type: EventBase
+ if not power_level_state_event:
+ return
+ power_level_content = power_level_state_event.content
+
+ # Do some validation checks on the power level state event
+ if (
+ not isinstance(power_level_content, dict)
+ or "users" not in power_level_content
+ or not isinstance(power_level_content["users"], dict)
+ ):
+ # We can't use this power level event to determine whether the room should be
+ # frozen. Bail out.
+ return
+
+ user_id = event.get("sender")
+ if not user_id:
+ return
+
+ # Get every admin user defined in the room's state
+ admin_users = {
+ user
+ for user, power_level in power_level_content["users"].items()
+ if power_level >= 100
+ }
+
+ if user_id not in admin_users:
+ # This user is not an admin, ignore them
+ return
+
+ if any(
+ event_type == EventTypes.Member
+ and event.membership in [Membership.JOIN, Membership.INVITE]
+ and state_key in admin_users
+ and state_key != user_id
+ for (event_type, state_key), event in state_events.items()
+ ):
+ # There's another admin user in, or invited to, the room
+ return
+
+ # Freeze the room by raising the required power level to send events to 100
+ logger.info("Freezing room '%s'", event.room_id)
+
+ # Modify the existing power levels to raise all required types to 100
+ #
+ # This changes a power level state event's content from something like:
+ # {
+ # "redact": 50,
+ # "state_default": 50,
+ # "ban": 50,
+ # "notifications": {
+ # "room": 50
+ # },
+ # "events": {
+ # "m.room.avatar": 50,
+ # "m.room.encryption": 50,
+ # "m.room.canonical_alias": 50,
+ # "m.room.name": 50,
+ # "im.vector.modular.widgets": 50,
+ # "m.room.topic": 50,
+ # "m.room.tombstone": 50,
+ # "m.room.history_visibility": 100,
+ # "m.room.power_levels": 100
+ # },
+ # "users_default": 0,
+ # "events_default": 0,
+ # "users": {
+ # "@admin:example.com": 100,
+ # },
+ # "kick": 50,
+ # "invite": 0
+ # }
+ #
+ # to
+ #
+ # {
+ # "redact": 100,
+ # "state_default": 100,
+ # "ban": 100,
+ # "notifications": {
+ # "room": 50
+ # },
+ # "events": {}
+ # "users_default": 0,
+ # "events_default": 100,
+ # "users": {
+ # "@admin:example.com": 100,
+ # },
+ # "kick": 100,
+ # "invite": 100
+ # }
+ new_content = {}
+ for key, value in power_level_content.items():
+ # Do not change "users_default", as that key specifies the default power
+ # level of new users
+ if isinstance(value, int) and key != "users_default":
+ value = 100
+ new_content[key] = value
+
+ # Set some values in case they are missing from the original
+ # power levels event content
+ new_content.update(
+ {
+ # Clear out any special-cased event keys
+ "events": {},
+ # Ensure state_default and events_default keys exist and are 100.
+ # Otherwise a lower PL user could potentially send state events that
+ # aren't explicitly mentioned elsewhere in the power level dict
+ "state_default": 100,
+ "events_default": 100,
+ # Membership events default to 50 if they aren't present. Set them
+ # to 100 here, as they would be set to 100 if they were present anyways
+ "ban": 100,
+ "kick": 100,
+ "invite": 100,
+ "redact": 100,
+ }
+ )
+
+ await self.module_api.create_and_send_event_into_room(
+ {
+ "room_id": event.room_id,
+ "sender": user_id,
+ "type": EventTypes.PowerLevels,
+ "content": new_content,
+ "state_key": "",
+ }
+ )
+
def _on_membership_or_invite_restricted(self, event: EventBase) -> bool:
"""Implements the checks and behaviour specified for the "restricted" rule.
@@ -753,6 +902,25 @@ class RoomAccessRules(object):
return token == threepid_invite_token
+ def _is_local_user(self, user_id: str) -> bool:
+ """Checks whether a given user ID belongs to this homeserver, or a remote
+
+ Args:
+ user_id: A user ID to check.
+
+ Returns:
+ True if the user belongs to this homeserver, False otherwise.
+ """
+ user = UserID.from_string(user_id)
+
+ # Extract the localpart and ask the module API for a user ID from the localpart
+ # The module API will append the local homeserver's server_name
+ local_user_id = self.module_api.get_qualified_user_id(user.localpart)
+
+ # If the user ID we get based on the localpart is the same as the original user ID,
+ # then they were a local user
+ return user_id == local_user_id
+
def _user_is_invited_to_room(
self, user_id: str, state_events: StateMap[EventBase]
) -> bool:
diff --git a/tests/rest/client/test_room_access_rules.py b/tests/rest/client/test_room_access_rules.py
index 6582cd288d..de7856fba9 100644
--- a/tests/rest/client/test_room_access_rules.py
+++ b/tests/rest/client/test_room_access_rules.py
@@ -15,6 +15,7 @@
import json
import random
import string
+from typing import Optional
from mock import Mock
@@ -28,7 +29,7 @@ from synapse.third_party_rules.access_rules import (
AccessRules,
RoomAccessRules,
)
-from synapse.types import create_requester
+from synapse.types import JsonDict, create_requester
from tests import unittest
@@ -840,6 +841,134 @@ class RoomAccessTestCase(unittest.HomeserverTestCase):
)
self.assertTrue(can_join)
+ def test_freezing_a_room(self):
+ """Tests that the power levels in a room change to prevent new events from
+ non-admin users when the last admin of a room leaves.
+ """
+
+ def freeze_room_with_id_and_power_levels(
+ room_id: str, custom_power_levels_content: Optional[JsonDict] = None,
+ ):
+ # Invite a user to the room, they join with PL 0
+ self.helper.invite(
+ room=room_id, src=self.user_id, targ=self.invitee_id, tok=self.tok,
+ )
+
+ # Invitee joins the room
+ self.helper.join(
+ room=room_id, user=self.invitee_id, tok=self.invitee_tok,
+ )
+
+ if not custom_power_levels_content:
+ # Retrieve the room's current power levels event content
+ power_levels = self.helper.get_state(
+ room_id=room_id, event_type="m.room.power_levels", tok=self.tok,
+ )
+ else:
+ power_levels = custom_power_levels_content
+
+ # Override the room's power levels with the given power levels content
+ self.helper.send_state(
+ room_id=room_id,
+ event_type="m.room.power_levels",
+ body=custom_power_levels_content,
+ tok=self.tok,
+ )
+
+ # Ensure that the invitee leaving the room does not change the power levels
+ self.helper.leave(
+ room=room_id, user=self.invitee_id, tok=self.invitee_tok,
+ )
+
+ # Retrieve the new power levels of the room
+ new_power_levels = self.helper.get_state(
+ room_id=room_id, event_type="m.room.power_levels", tok=self.tok,
+ )
+
+ # Ensure they have not changed
+ self.assertDictEqual(power_levels, new_power_levels)
+
+ # Invite the user back again
+ self.helper.invite(
+ room=room_id, src=self.user_id, targ=self.invitee_id, tok=self.tok,
+ )
+
+ # Invitee joins the room
+ self.helper.join(
+ room=room_id, user=self.invitee_id, tok=self.invitee_tok,
+ )
+
+ # Now the admin leaves the room
+ self.helper.leave(
+ room=room_id, user=self.user_id, tok=self.tok,
+ )
+
+ # Check the power levels again
+ new_power_levels = self.helper.get_state(
+ room_id=room_id, event_type="m.room.power_levels", tok=self.invitee_tok,
+ )
+
+ # Ensure that the new power levels prevent anyone but admins from sending
+ # certain events
+ self.assertEquals(new_power_levels["state_default"], 100)
+ self.assertEquals(new_power_levels["events_default"], 100)
+ self.assertEquals(new_power_levels["kick"], 100)
+ self.assertEquals(new_power_levels["invite"], 100)
+ self.assertEquals(new_power_levels["ban"], 100)
+ self.assertEquals(new_power_levels["redact"], 100)
+ self.assertDictEqual(new_power_levels["events"], {})
+ self.assertDictEqual(new_power_levels["users"], {self.user_id: 100})
+
+ # Ensure new users entering the room aren't going to immediately become admins
+ self.assertEquals(new_power_levels["users_default"], 0)
+
+ # Test that freezing a room with the default power level state event content works
+ room1 = self.create_room()
+ freeze_room_with_id_and_power_levels(room1)
+
+ # Test that freezing a room with a power level state event that is missing
+ # `state_default` and `event_default` keys behaves as expected
+ room2 = self.create_room()
+ freeze_room_with_id_and_power_levels(
+ room2,
+ {
+ "ban": 50,
+ "events": {
+ "m.room.avatar": 50,
+ "m.room.canonical_alias": 50,
+ "m.room.history_visibility": 100,
+ "m.room.name": 50,
+ "m.room.power_levels": 100,
+ },
+ "invite": 0,
+ "kick": 50,
+ "redact": 50,
+ "users": {self.user_id: 100},
+ "users_default": 0,
+ # Explicitly remove `state_default` and `event_default` keys
+ },
+ )
+
+ # Test that freezing a room with a power level state event that is *additionally*
+ # missing `ban`, `invite`, `kick` and `redact` keys behaves as expected
+ room3 = self.create_room()
+ freeze_room_with_id_and_power_levels(
+ room3,
+ {
+ "events": {
+ "m.room.avatar": 50,
+ "m.room.canonical_alias": 50,
+ "m.room.history_visibility": 100,
+ "m.room.name": 50,
+ "m.room.power_levels": 100,
+ },
+ "users": {self.user_id: 100},
+ "users_default": 0,
+ # Explicitly remove `state_default` and `event_default` keys
+ # Explicitly remove `ban`, `invite`, `kick` and `redact` keys
+ },
+ )
+
def create_room(
self,
direct=False,
|
