168 lines
6.1 KiB
Python
168 lines
6.1 KiB
Python
# Copyright 2021 The Matrix.org Foundation C.I.C.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from typing import TYPE_CHECKING, Collection, Optional
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from synapse.api.constants import EventTypes, JoinRules, Membership
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from synapse.api.errors import AuthError
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from synapse.api.room_versions import RoomVersion
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from synapse.events import EventBase
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from synapse.types import StateMap
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if TYPE_CHECKING:
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from synapse.server import HomeServer
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class EventAuthHandler:
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"""
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This class contains methods for authenticating events added to room graphs.
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"""
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def __init__(self, hs: "HomeServer"):
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self._store = hs.get_datastore()
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async def check_restricted_join_rules(
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self,
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state_ids: StateMap[str],
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room_version: RoomVersion,
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user_id: str,
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prev_member_event: Optional[EventBase],
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) -> None:
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"""
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Check whether a user can join a room without an invite due to restricted join rules.
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When joining a room with restricted joined rules (as defined in MSC3083),
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the membership of spaces must be checked during a room join.
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Args:
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state_ids: The state of the room as it currently is.
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room_version: The room version of the room being joined.
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user_id: The user joining the room.
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prev_member_event: The current membership event for this user.
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Raises:
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AuthError if the user cannot join the room.
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"""
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# If the member is invited or currently joined, then nothing to do.
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if prev_member_event and (
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prev_member_event.membership in (Membership.JOIN, Membership.INVITE)
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):
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return
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# This is not a room with a restricted join rule, so we don't need to do the
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# restricted room specific checks.
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#
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# Note: We'll be applying the standard join rule checks later, which will
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# catch the cases of e.g. trying to join private rooms without an invite.
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if not await self.has_restricted_join_rules(state_ids, room_version):
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return
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# Get the spaces which allow access to this room and check if the user is
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# in any of them.
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allowed_spaces = await self.get_spaces_that_allow_join(state_ids)
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if not await self.is_user_in_rooms(allowed_spaces, user_id):
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raise AuthError(
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403,
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"You do not belong to any of the required spaces to join this room.",
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)
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async def has_restricted_join_rules(
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self, state_ids: StateMap[str], room_version: RoomVersion
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) -> bool:
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"""
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Return if the room has the proper join rules set for access via spaces.
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Args:
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state_ids: The state of the room as it currently is.
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room_version: The room version of the room to query.
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Returns:
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True if the proper room version and join rules are set for restricted access.
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"""
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# This only applies to room versions which support the new join rule.
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if not room_version.msc3083_join_rules:
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return False
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# If there's no join rule, then it defaults to invite (so this doesn't apply).
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join_rules_event_id = state_ids.get((EventTypes.JoinRules, ""), None)
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if not join_rules_event_id:
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return False
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# If the join rule is not restricted, this doesn't apply.
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join_rules_event = await self._store.get_event(join_rules_event_id)
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return join_rules_event.content.get("join_rule") == JoinRules.MSC3083_RESTRICTED
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async def get_spaces_that_allow_join(
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self, state_ids: StateMap[str]
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) -> Collection[str]:
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"""
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Generate a list of spaces which allow access to a room.
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Args:
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state_ids: The state of the room as it currently is.
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Returns:
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A collection of spaces which provide membership to the room.
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"""
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# If there's no join rule, then it defaults to invite (so this doesn't apply).
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join_rules_event_id = state_ids.get((EventTypes.JoinRules, ""), None)
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if not join_rules_event_id:
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return ()
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# If the join rule is not restricted, this doesn't apply.
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join_rules_event = await self._store.get_event(join_rules_event_id)
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# If allowed is of the wrong form, then only allow invited users.
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allowed_spaces = join_rules_event.content.get("allow", [])
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if not isinstance(allowed_spaces, list):
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return ()
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# Pull out the other room IDs, invalid data gets filtered.
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result = []
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for space in allowed_spaces:
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if not isinstance(space, dict):
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continue
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space_id = space.get("space")
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if not isinstance(space_id, str):
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continue
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result.append(space_id)
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return result
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async def is_user_in_rooms(self, room_ids: Collection[str], user_id: str) -> bool:
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"""
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Check whether a user is a member of any of the provided rooms.
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Args:
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room_ids: The rooms to check for membership.
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user_id: The user to check.
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Returns:
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True if the user is in any of the rooms, false otherwise.
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"""
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if not room_ids:
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return False
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# Get the list of joined rooms and see if there's an overlap.
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joined_rooms = await self._store.get_rooms_for_user(user_id)
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# Check each room and see if the user is in it.
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for room_id in room_ids:
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if room_id in joined_rooms:
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return True
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# The user was not in any of the rooms.
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return False
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