From d924827da1db5d210eb06db2247a1403ed4c8b9a Mon Sep 17 00:00:00 2001 From: Patrick Cloke Date: Fri, 23 Apr 2021 07:05:51 -0400 Subject: Check for space membership during a remote join of a restricted room (#9814) When receiving a /send_join request for a room with join rules set to 'restricted', check if the user is a member of the spaces defined in the 'allow' key of the join rules. This only applies to an experimental room version, as defined in MSC3083. --- synapse/handlers/event_auth.py | 86 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 86 insertions(+) create mode 100644 synapse/handlers/event_auth.py (limited to 'synapse/handlers/event_auth.py') diff --git a/synapse/handlers/event_auth.py b/synapse/handlers/event_auth.py new file mode 100644 index 0000000000..eff639f407 --- /dev/null +++ b/synapse/handlers/event_auth.py @@ -0,0 +1,86 @@ +# Copyright 2021 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 typing import TYPE_CHECKING + +from synapse.api.constants import EventTypes, JoinRules +from synapse.api.room_versions import RoomVersion +from synapse.types import StateMap + +if TYPE_CHECKING: + from synapse.server import HomeServer + + +class EventAuthHandler: + """ + This class contains methods for authenticating events added to room graphs. + """ + + def __init__(self, hs: "HomeServer"): + self._store = hs.get_datastore() + + async def can_join_without_invite( + self, state_ids: StateMap[str], room_version: RoomVersion, user_id: str + ) -> bool: + """ + Check whether a user can join a room without an invite. + + When joining a room with restricted joined rules (as defined in MSC3083), + the membership of spaces must be checked during join. + + Args: + state_ids: The state of the room as it currently is. + room_version: The room version of the room being joined. + user_id: The user joining the room. + + Returns: + True if the user can join the room, false otherwise. + """ + # This only applies to room versions which support the new join rule. + if not room_version.msc3083_join_rules: + return True + + # If there's no join rule, then it defaults to invite (so this doesn't apply). + join_rules_event_id = state_ids.get((EventTypes.JoinRules, ""), None) + if not join_rules_event_id: + return True + + # If the join rule is not restricted, this doesn't apply. + join_rules_event = await self._store.get_event(join_rules_event_id) + if join_rules_event.content.get("join_rule") != JoinRules.MSC3083_RESTRICTED: + return True + + # If allowed is of the wrong form, then only allow invited users. + allowed_spaces = join_rules_event.content.get("allow", []) + if not isinstance(allowed_spaces, list): + return False + + # Get the list of joined rooms and see if there's an overlap. + joined_rooms = await self._store.get_rooms_for_user(user_id) + + # Pull out the other room IDs, invalid data gets filtered. + for space in allowed_spaces: + if not isinstance(space, dict): + continue + + space_id = space.get("space") + if not isinstance(space_id, str): + continue + + # The user was joined to one of the spaces specified, they can join + # this room! + if space_id in joined_rooms: + return True + + # The user was not in any of the required spaces. + return False -- cgit 1.4.1