352 lines
13 KiB
Python
352 lines
13 KiB
Python
# Copyright 2023 The Matrix.org Foundation.
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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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import logging
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from typing import TYPE_CHECKING, Optional, Tuple
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from netaddr import IPAddress
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from twisted.web.server import Request
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from synapse import event_auth
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from synapse.api.constants import EventTypes, HistoryVisibility, Membership
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from synapse.api.errors import (
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AuthError,
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Codes,
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MissingClientTokenError,
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UnstableSpecAuthError,
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)
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from synapse.appservice import ApplicationService
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from synapse.logging.opentracing import trace
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from synapse.types import Requester, create_requester
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from synapse.util.cancellation import cancellable
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if TYPE_CHECKING:
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from synapse.server import HomeServer
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logger = logging.getLogger(__name__)
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class BaseAuth:
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"""Common base class for all auth implementations."""
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def __init__(self, hs: "HomeServer"):
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self.hs = hs
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self.store = hs.get_datastores().main
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self._storage_controllers = hs.get_storage_controllers()
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async def check_user_in_room(
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self,
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room_id: str,
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requester: Requester,
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allow_departed_users: bool = False,
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) -> Tuple[str, Optional[str]]:
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"""Check if the user is in the room, or was at some point.
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Args:
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room_id: The room to check.
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requester: The user making the request, according to the access token.
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current_state: Optional map of the current state of the room.
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If provided then that map is used to check whether they are a
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member of the room. Otherwise the current membership is
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loaded from the database.
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allow_departed_users: if True, accept users that were previously
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members but have now departed.
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Raises:
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AuthError if the user is/was not in the room.
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Returns:
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The current membership of the user in the room and the
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membership event ID of the user.
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"""
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user_id = requester.user.to_string()
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(
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membership,
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member_event_id,
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) = await self.store.get_local_current_membership_for_user_in_room(
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user_id=user_id,
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room_id=room_id,
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)
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if membership:
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if membership == Membership.JOIN:
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return membership, member_event_id
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# XXX this looks totally bogus. Why do we not allow users who have been banned,
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# or those who were members previously and have been re-invited?
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if allow_departed_users and membership == Membership.LEAVE:
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forgot = await self.store.did_forget(user_id, room_id)
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if not forgot:
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return membership, member_event_id
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raise UnstableSpecAuthError(
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403,
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"User %s not in room %s" % (user_id, room_id),
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errcode=Codes.NOT_JOINED,
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)
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@trace
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async def check_user_in_room_or_world_readable(
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self, room_id: str, requester: Requester, allow_departed_users: bool = False
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) -> Tuple[str, Optional[str]]:
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"""Checks that the user is or was in the room or the room is world
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readable. If it isn't then an exception is raised.
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Args:
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room_id: room to check
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user_id: user to check
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allow_departed_users: if True, accept users that were previously
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members but have now departed
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Returns:
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Resolves to the current membership of the user in the room and the
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membership event ID of the user. If the user is not in the room and
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never has been, then `(Membership.JOIN, None)` is returned.
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"""
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try:
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# check_user_in_room will return the most recent membership
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# event for the user if:
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# * The user is a non-guest user, and was ever in the room
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# * The user is a guest user, and has joined the room
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# else it will throw.
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return await self.check_user_in_room(
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room_id, requester, allow_departed_users=allow_departed_users
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)
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except AuthError:
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visibility = await self._storage_controllers.state.get_current_state_event(
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room_id, EventTypes.RoomHistoryVisibility, ""
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)
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if (
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visibility
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and visibility.content.get("history_visibility")
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== HistoryVisibility.WORLD_READABLE
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):
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return Membership.JOIN, None
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raise AuthError(
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403,
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"User %r not in room %s, and room previews are disabled"
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% (requester.user, room_id),
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)
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async def validate_appservice_can_control_user_id(
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self, app_service: ApplicationService, user_id: str
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) -> None:
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"""Validates that the app service is allowed to control
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the given user.
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Args:
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app_service: The app service that controls the user
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user_id: The author MXID that the app service is controlling
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Raises:
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AuthError: If the application service is not allowed to control the user
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(user namespace regex does not match, wrong homeserver, etc)
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or if the user has not been registered yet.
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"""
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# It's ok if the app service is trying to use the sender from their registration
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if app_service.sender == user_id:
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pass
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# Check to make sure the app service is allowed to control the user
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elif not app_service.is_interested_in_user(user_id):
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raise AuthError(
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403,
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"Application service cannot masquerade as this user (%s)." % user_id,
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)
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# Check to make sure the user is already registered on the homeserver
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elif not (await self.store.get_user_by_id(user_id)):
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raise AuthError(
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403, "Application service has not registered this user (%s)" % user_id
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)
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async def is_server_admin(self, requester: Requester) -> bool:
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"""Check if the given user is a local server admin.
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Args:
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requester: user to check
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Returns:
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True if the user is an admin
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"""
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raise NotImplementedError()
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async def check_can_change_room_list(
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self, room_id: str, requester: Requester
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) -> bool:
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"""Determine whether the user is allowed to edit the room's entry in the
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published room list.
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Args:
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room_id
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user
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"""
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is_admin = await self.is_server_admin(requester)
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if is_admin:
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return True
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await self.check_user_in_room(room_id, requester)
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# We currently require the user is a "moderator" in the room. We do this
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# by checking if they would (theoretically) be able to change the
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# m.room.canonical_alias events
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power_level_event = (
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await self._storage_controllers.state.get_current_state_event(
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room_id, EventTypes.PowerLevels, ""
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)
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)
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auth_events = {}
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if power_level_event:
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auth_events[(EventTypes.PowerLevels, "")] = power_level_event
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send_level = event_auth.get_send_level(
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EventTypes.CanonicalAlias, "", power_level_event
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)
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user_level = event_auth.get_user_power_level(
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requester.user.to_string(), auth_events
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)
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return user_level >= send_level
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@staticmethod
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def has_access_token(request: Request) -> bool:
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"""Checks if the request has an access_token.
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Returns:
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False if no access_token was given, True otherwise.
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"""
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# This will always be set by the time Twisted calls us.
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assert request.args is not None
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query_params = request.args.get(b"access_token")
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auth_headers = request.requestHeaders.getRawHeaders(b"Authorization")
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return bool(query_params) or bool(auth_headers)
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@staticmethod
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def get_access_token_from_request(request: Request) -> str:
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"""Extracts the access_token from the request.
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Args:
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request: The http request.
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Returns:
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The access_token
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Raises:
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MissingClientTokenError: If there isn't a single access_token in the
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request
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"""
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# This will always be set by the time Twisted calls us.
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assert request.args is not None
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auth_headers = request.requestHeaders.getRawHeaders(b"Authorization")
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query_params = request.args.get(b"access_token")
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if auth_headers:
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# Try the get the access_token from a "Authorization: Bearer"
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# header
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if query_params is not None:
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raise MissingClientTokenError(
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"Mixing Authorization headers and access_token query parameters."
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)
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if len(auth_headers) > 1:
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raise MissingClientTokenError("Too many Authorization headers.")
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parts = auth_headers[0].split(b" ")
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if parts[0] == b"Bearer" and len(parts) == 2:
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return parts[1].decode("ascii")
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else:
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raise MissingClientTokenError("Invalid Authorization header.")
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else:
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# Try to get the access_token from the query params.
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if not query_params:
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raise MissingClientTokenError()
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return query_params[0].decode("ascii")
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@cancellable
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async def get_appservice_user(
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self, request: Request, access_token: str
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) -> Optional[Requester]:
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"""
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Given a request, reads the request parameters to determine:
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- whether it's an application service that's making this request
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- what user the application service should be treated as controlling
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(the user_id URI parameter allows an application service to masquerade
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any applicable user in its namespace)
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- what device the application service should be treated as controlling
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(the device_id[^1] URI parameter allows an application service to masquerade
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as any device that exists for the relevant user)
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[^1] Unstable and provided by MSC3202.
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Must use `org.matrix.msc3202.device_id` in place of `device_id` for now.
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Returns:
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the application service `Requester` of that request
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Postconditions:
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- The `app_service` field in the returned `Requester` is set
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- The `user_id` field in the returned `Requester` is either the application
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service sender or the controlled user set by the `user_id` URI parameter
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- The returned application service is permitted to control the returned user ID.
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- The returned device ID, if present, has been checked to be a valid device ID
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for the returned user ID.
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"""
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DEVICE_ID_ARG_NAME = b"org.matrix.msc3202.device_id"
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app_service = self.store.get_app_service_by_token(access_token)
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if app_service is None:
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return None
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if app_service.ip_range_whitelist:
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ip_address = IPAddress(request.getClientAddress().host)
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if ip_address not in app_service.ip_range_whitelist:
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return None
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# This will always be set by the time Twisted calls us.
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assert request.args is not None
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if b"user_id" in request.args:
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effective_user_id = request.args[b"user_id"][0].decode("utf8")
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await self.validate_appservice_can_control_user_id(
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app_service, effective_user_id
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)
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else:
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effective_user_id = app_service.sender
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effective_device_id: Optional[str] = None
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if (
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self.hs.config.experimental.msc3202_device_masquerading_enabled
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and DEVICE_ID_ARG_NAME in request.args
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):
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effective_device_id = request.args[DEVICE_ID_ARG_NAME][0].decode("utf8")
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# We only just set this so it can't be None!
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assert effective_device_id is not None
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device_opt = await self.store.get_device(
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effective_user_id, effective_device_id
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)
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if device_opt is None:
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# For now, use 400 M_EXCLUSIVE if the device doesn't exist.
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# This is an open thread of discussion on MSC3202 as of 2021-12-09.
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raise AuthError(
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400,
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f"Application service trying to use a device that doesn't exist ('{effective_device_id}' for {effective_user_id})",
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Codes.EXCLUSIVE,
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)
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return create_requester(
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effective_user_id, app_service=app_service, device_id=effective_device_id
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)
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