887 lines
		
	
	
		
			32 KiB
		
	
	
	
		
			Python
		
	
	
			
		
		
	
	
			887 lines
		
	
	
		
			32 KiB
		
	
	
	
		
			Python
		
	
	
| # Copyright 2014 - 2016 OpenMarket Ltd
 | |
| # 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.
 | |
| 
 | |
| import logging
 | |
| from typing import Any, Dict, List, Optional, Set, Tuple, Union
 | |
| 
 | |
| from canonicaljson import encode_canonical_json
 | |
| from signedjson.key import decode_verify_key_bytes
 | |
| from signedjson.sign import SignatureVerifyException, verify_signed_json
 | |
| from unpaddedbase64 import decode_base64
 | |
| 
 | |
| from synapse.api.constants import (
 | |
|     MAX_PDU_SIZE,
 | |
|     EventContentFields,
 | |
|     EventTypes,
 | |
|     JoinRules,
 | |
|     Membership,
 | |
| )
 | |
| from synapse.api.errors import AuthError, EventSizeError, SynapseError
 | |
| from synapse.api.room_versions import (
 | |
|     KNOWN_ROOM_VERSIONS,
 | |
|     EventFormatVersions,
 | |
|     RoomVersion,
 | |
| )
 | |
| from synapse.events import EventBase
 | |
| from synapse.events.builder import EventBuilder
 | |
| from synapse.types import StateMap, UserID, get_domain_from_id
 | |
| 
 | |
| logger = logging.getLogger(__name__)
 | |
| 
 | |
| 
 | |
| def validate_event_for_room_version(
 | |
|     room_version_obj: RoomVersion, event: EventBase
 | |
| ) -> None:
 | |
|     """Ensure that the event complies with the limits, and has the right signatures
 | |
| 
 | |
|     NB: does not *validate* the signatures - it assumes that any signatures present
 | |
|     have already been checked.
 | |
| 
 | |
|     NB: it does not check that the event satisfies the auth rules (that is done in
 | |
|     check_auth_rules_for_event) - these tests are independent of the rest of the state
 | |
|     in the room.
 | |
| 
 | |
|     NB: This is used to check events that have been received over federation. As such,
 | |
|     it can only enforce the checks specified in the relevant room version, to avoid
 | |
|     a split-brain situation where some servers accept such events, and others reject
 | |
|     them.
 | |
| 
 | |
|     TODO: consider moving this into EventValidator
 | |
| 
 | |
|     Args:
 | |
|         room_version_obj: the version of the room which contains this event
 | |
|         event: the event to be checked
 | |
| 
 | |
|     Raises:
 | |
|         SynapseError if there is a problem with the event
 | |
|     """
 | |
|     _check_size_limits(event)
 | |
| 
 | |
|     if not hasattr(event, "room_id"):
 | |
|         raise AuthError(500, "Event has no room_id: %s" % event)
 | |
| 
 | |
|     # check that the event has the correct signatures
 | |
|     sender_domain = get_domain_from_id(event.sender)
 | |
| 
 | |
|     is_invite_via_3pid = (
 | |
|         event.type == EventTypes.Member
 | |
|         and event.membership == Membership.INVITE
 | |
|         and "third_party_invite" in event.content
 | |
|     )
 | |
| 
 | |
|     # Check the sender's domain has signed the event
 | |
|     if not event.signatures.get(sender_domain):
 | |
|         # We allow invites via 3pid to have a sender from a different
 | |
|         # HS, as the sender must match the sender of the original
 | |
|         # 3pid invite. This is checked further down with the
 | |
|         # other dedicated membership checks.
 | |
|         if not is_invite_via_3pid:
 | |
|             raise AuthError(403, "Event not signed by sender's server")
 | |
| 
 | |
|     if event.format_version in (EventFormatVersions.V1,):
 | |
|         # Only older room versions have event IDs to check.
 | |
|         event_id_domain = get_domain_from_id(event.event_id)
 | |
| 
 | |
|         # Check the origin domain has signed the event
 | |
|         if not event.signatures.get(event_id_domain):
 | |
|             raise AuthError(403, "Event not signed by sending server")
 | |
| 
 | |
|     is_invite_via_allow_rule = (
 | |
|         room_version_obj.msc3083_join_rules
 | |
|         and event.type == EventTypes.Member
 | |
|         and event.membership == Membership.JOIN
 | |
|         and EventContentFields.AUTHORISING_USER in event.content
 | |
|     )
 | |
|     if is_invite_via_allow_rule:
 | |
|         authoriser_domain = get_domain_from_id(
 | |
|             event.content[EventContentFields.AUTHORISING_USER]
 | |
|         )
 | |
|         if not event.signatures.get(authoriser_domain):
 | |
|             raise AuthError(403, "Event not signed by authorising server")
 | |
| 
 | |
| 
 | |
| def check_auth_rules_for_event(
 | |
|     room_version_obj: RoomVersion, event: EventBase, auth_events: StateMap[EventBase]
 | |
| ) -> None:
 | |
|     """Check that an event complies with the auth rules
 | |
| 
 | |
|     Checks whether an event passes the auth rules with a given set of state events
 | |
| 
 | |
|     Assumes that we have already checked that the event is the right shape (it has
 | |
|     enough signatures, has a room ID, etc). In other words:
 | |
| 
 | |
|      - it's fine for use in state resolution, when we have already decided whether to
 | |
|        accept the event or not, and are now trying to decide whether it should make it
 | |
|        into the room state
 | |
| 
 | |
|      - when we're doing the initial event auth, it is only suitable in combination with
 | |
|        a bunch of other tests.
 | |
| 
 | |
|     Args:
 | |
|         room_version_obj: the version of the room
 | |
|         event: the event being checked.
 | |
|         auth_events: the room state to check the events against.
 | |
| 
 | |
|     Raises:
 | |
|         AuthError if the checks fail
 | |
|     """
 | |
|     assert isinstance(auth_events, dict)
 | |
| 
 | |
|     # We need to ensure that the auth events are actually for the same room, to
 | |
|     # stop people from using powers they've been granted in other rooms for
 | |
|     # example.
 | |
|     #
 | |
|     # Arguably we don't need to do this when we're just doing state res, as presumably
 | |
|     # the state res algorithm isn't silly enough to give us events from different rooms.
 | |
|     # Still, it's easier to do it anyway.
 | |
|     room_id = event.room_id
 | |
|     for auth_event in auth_events.values():
 | |
|         if auth_event.room_id != room_id:
 | |
|             raise AuthError(
 | |
|                 403,
 | |
|                 "During auth for event %s in room %s, found event %s in the state "
 | |
|                 "which is in room %s"
 | |
|                 % (event.event_id, room_id, auth_event.event_id, auth_event.room_id),
 | |
|             )
 | |
|         if auth_event.rejected_reason:
 | |
|             raise AuthError(
 | |
|                 403,
 | |
|                 "During auth for event %s: found rejected event %s in the state"
 | |
|                 % (event.event_id, auth_event.event_id),
 | |
|             )
 | |
| 
 | |
|     # Implementation of https://matrix.org/docs/spec/rooms/v1#authorization-rules
 | |
|     #
 | |
|     # 1. If type is m.room.create:
 | |
|     if event.type == EventTypes.Create:
 | |
|         # 1b. If the domain of the room_id does not match the domain of the sender,
 | |
|         # reject.
 | |
|         sender_domain = get_domain_from_id(event.sender)
 | |
|         room_id_domain = get_domain_from_id(event.room_id)
 | |
|         if room_id_domain != sender_domain:
 | |
|             raise AuthError(
 | |
|                 403, "Creation event's room_id domain does not match sender's"
 | |
|             )
 | |
| 
 | |
|         # 1c. If content.room_version is present and is not a recognised version, reject
 | |
|         room_version_prop = event.content.get("room_version", "1")
 | |
|         if room_version_prop not in KNOWN_ROOM_VERSIONS:
 | |
|             raise AuthError(
 | |
|                 403,
 | |
|                 "room appears to have unsupported version %s" % (room_version_prop,),
 | |
|             )
 | |
| 
 | |
|         logger.debug("Allowing! %s", event)
 | |
|         return
 | |
| 
 | |
|     # 3. If event does not have a m.room.create in its auth_events, reject.
 | |
|     creation_event = auth_events.get((EventTypes.Create, ""), None)
 | |
|     if not creation_event:
 | |
|         raise AuthError(403, "No create event in auth events")
 | |
| 
 | |
|     # additional check for m.federate
 | |
|     creating_domain = get_domain_from_id(event.room_id)
 | |
|     originating_domain = get_domain_from_id(event.sender)
 | |
|     if creating_domain != originating_domain:
 | |
|         if not _can_federate(event, auth_events):
 | |
|             raise AuthError(403, "This room has been marked as unfederatable.")
 | |
| 
 | |
|     # 4. If type is m.room.aliases
 | |
|     if event.type == EventTypes.Aliases and room_version_obj.special_case_aliases_auth:
 | |
|         # 4a. If event has no state_key, reject
 | |
|         if not event.is_state():
 | |
|             raise AuthError(403, "Alias event must be a state event")
 | |
|         if not event.state_key:
 | |
|             raise AuthError(403, "Alias event must have non-empty state_key")
 | |
| 
 | |
|         # 4b. If sender's domain doesn't matches [sic] state_key, reject
 | |
|         sender_domain = get_domain_from_id(event.sender)
 | |
|         if event.state_key != sender_domain:
 | |
|             raise AuthError(
 | |
|                 403, "Alias event's state_key does not match sender's domain"
 | |
|             )
 | |
| 
 | |
|         # 4c. Otherwise, allow.
 | |
|         logger.debug("Allowing! %s", event)
 | |
|         return
 | |
| 
 | |
|     if logger.isEnabledFor(logging.DEBUG):
 | |
|         logger.debug("Auth events: %s", [a.event_id for a in auth_events.values()])
 | |
| 
 | |
|     # 5. If type is m.room.membership
 | |
|     if event.type == EventTypes.Member:
 | |
|         _is_membership_change_allowed(room_version_obj, event, auth_events)
 | |
|         logger.debug("Allowing! %s", event)
 | |
|         return
 | |
| 
 | |
|     _check_event_sender_in_room(event, auth_events)
 | |
| 
 | |
|     # Special case to allow m.room.third_party_invite events wherever
 | |
|     # a user is allowed to issue invites.  Fixes
 | |
|     # https://github.com/vector-im/vector-web/issues/1208 hopefully
 | |
|     if event.type == EventTypes.ThirdPartyInvite:
 | |
|         user_level = get_user_power_level(event.user_id, auth_events)
 | |
|         invite_level = get_named_level(auth_events, "invite", 0)
 | |
| 
 | |
|         if user_level < invite_level:
 | |
|             raise AuthError(403, "You don't have permission to invite users")
 | |
|         else:
 | |
|             logger.debug("Allowing! %s", event)
 | |
|             return
 | |
| 
 | |
|     _can_send_event(event, auth_events)
 | |
| 
 | |
|     if event.type == EventTypes.PowerLevels:
 | |
|         _check_power_levels(room_version_obj, event, auth_events)
 | |
| 
 | |
|     if event.type == EventTypes.Redaction:
 | |
|         check_redaction(room_version_obj, event, auth_events)
 | |
| 
 | |
|     if (
 | |
|         event.type == EventTypes.MSC2716_INSERTION
 | |
|         or event.type == EventTypes.MSC2716_BATCH
 | |
|         or event.type == EventTypes.MSC2716_MARKER
 | |
|     ):
 | |
|         check_historical(room_version_obj, event, auth_events)
 | |
| 
 | |
|     logger.debug("Allowing! %s", event)
 | |
| 
 | |
| 
 | |
| def _check_size_limits(event: EventBase) -> None:
 | |
|     if len(event.user_id) > 255:
 | |
|         raise EventSizeError("'user_id' too large")
 | |
|     if len(event.room_id) > 255:
 | |
|         raise EventSizeError("'room_id' too large")
 | |
|     if event.is_state() and len(event.state_key) > 255:
 | |
|         raise EventSizeError("'state_key' too large")
 | |
|     if len(event.type) > 255:
 | |
|         raise EventSizeError("'type' too large")
 | |
|     if len(event.event_id) > 255:
 | |
|         raise EventSizeError("'event_id' too large")
 | |
|     if len(encode_canonical_json(event.get_pdu_json())) > MAX_PDU_SIZE:
 | |
|         raise EventSizeError("event too large")
 | |
| 
 | |
| 
 | |
| def _can_federate(event: EventBase, auth_events: StateMap[EventBase]) -> bool:
 | |
|     creation_event = auth_events.get((EventTypes.Create, ""))
 | |
|     # There should always be a creation event, but if not don't federate.
 | |
|     if not creation_event:
 | |
|         return False
 | |
| 
 | |
|     return creation_event.content.get(EventContentFields.FEDERATE, True) is True
 | |
| 
 | |
| 
 | |
| def _is_membership_change_allowed(
 | |
|     room_version: RoomVersion, event: EventBase, auth_events: StateMap[EventBase]
 | |
| ) -> None:
 | |
|     """
 | |
|     Confirms that the event which changes membership is an allowed change.
 | |
| 
 | |
|     Args:
 | |
|         room_version: The version of the room.
 | |
|         event: The event to check.
 | |
|         auth_events: The current auth events of the room.
 | |
| 
 | |
|     Raises:
 | |
|         AuthError if the event is not allowed.
 | |
|     """
 | |
|     membership = event.content["membership"]
 | |
| 
 | |
|     # Check if this is the room creator joining:
 | |
|     if len(event.prev_event_ids()) == 1 and Membership.JOIN == membership:
 | |
|         # Get room creation event:
 | |
|         key = (EventTypes.Create, "")
 | |
|         create = auth_events.get(key)
 | |
|         if create and event.prev_event_ids()[0] == create.event_id:
 | |
|             if create.content["creator"] == event.state_key:
 | |
|                 return
 | |
| 
 | |
|     target_user_id = event.state_key
 | |
| 
 | |
|     creating_domain = get_domain_from_id(event.room_id)
 | |
|     target_domain = get_domain_from_id(target_user_id)
 | |
|     if creating_domain != target_domain:
 | |
|         if not _can_federate(event, auth_events):
 | |
|             raise AuthError(403, "This room has been marked as unfederatable.")
 | |
| 
 | |
|     # get info about the caller
 | |
|     key = (EventTypes.Member, event.user_id)
 | |
|     caller = auth_events.get(key)
 | |
| 
 | |
|     caller_in_room = caller and caller.membership == Membership.JOIN
 | |
|     caller_invited = caller and caller.membership == Membership.INVITE
 | |
|     caller_knocked = (
 | |
|         caller
 | |
|         and room_version.msc2403_knocking
 | |
|         and caller.membership == Membership.KNOCK
 | |
|     )
 | |
| 
 | |
|     # get info about the target
 | |
|     key = (EventTypes.Member, target_user_id)
 | |
|     target = auth_events.get(key)
 | |
| 
 | |
|     target_in_room = target and target.membership == Membership.JOIN
 | |
|     target_banned = target and target.membership == Membership.BAN
 | |
| 
 | |
|     key = (EventTypes.JoinRules, "")
 | |
|     join_rule_event = auth_events.get(key)
 | |
|     if join_rule_event:
 | |
|         join_rule = join_rule_event.content.get("join_rule", JoinRules.INVITE)
 | |
|     else:
 | |
|         join_rule = JoinRules.INVITE
 | |
| 
 | |
|     user_level = get_user_power_level(event.user_id, auth_events)
 | |
|     target_level = get_user_power_level(target_user_id, auth_events)
 | |
| 
 | |
|     invite_level = get_named_level(auth_events, "invite", 0)
 | |
|     ban_level = get_named_level(auth_events, "ban", 50)
 | |
| 
 | |
|     logger.debug(
 | |
|         "_is_membership_change_allowed: %s",
 | |
|         {
 | |
|             "caller_in_room": caller_in_room,
 | |
|             "caller_invited": caller_invited,
 | |
|             "caller_knocked": caller_knocked,
 | |
|             "target_banned": target_banned,
 | |
|             "target_in_room": target_in_room,
 | |
|             "membership": membership,
 | |
|             "join_rule": join_rule,
 | |
|             "target_user_id": target_user_id,
 | |
|             "event.user_id": event.user_id,
 | |
|         },
 | |
|     )
 | |
| 
 | |
|     if Membership.INVITE == membership and "third_party_invite" in event.content:
 | |
|         if not _verify_third_party_invite(event, auth_events):
 | |
|             raise AuthError(403, "You are not invited to this room.")
 | |
|         if target_banned:
 | |
|             raise AuthError(403, "%s is banned from the room" % (target_user_id,))
 | |
|         return
 | |
| 
 | |
|     # Require the user to be in the room for membership changes other than join/knock.
 | |
|     if Membership.JOIN != membership and (
 | |
|         RoomVersion.msc2403_knocking and Membership.KNOCK != membership
 | |
|     ):
 | |
|         # If the user has been invited or has knocked, they are allowed to change their
 | |
|         # membership event to leave
 | |
|         if (
 | |
|             (caller_invited or caller_knocked)
 | |
|             and Membership.LEAVE == membership
 | |
|             and target_user_id == event.user_id
 | |
|         ):
 | |
|             return
 | |
| 
 | |
|         if not caller_in_room:  # caller isn't joined
 | |
|             raise AuthError(403, "%s not in room %s." % (event.user_id, event.room_id))
 | |
| 
 | |
|     if Membership.INVITE == membership:
 | |
|         # TODO (erikj): We should probably handle this more intelligently
 | |
|         # PRIVATE join rules.
 | |
| 
 | |
|         # Invites are valid iff caller is in the room and target isn't.
 | |
|         if target_banned:
 | |
|             raise AuthError(403, "%s is banned from the room" % (target_user_id,))
 | |
|         elif target_in_room:  # the target is already in the room.
 | |
|             raise AuthError(403, "%s is already in the room." % target_user_id)
 | |
|         else:
 | |
|             if user_level < invite_level:
 | |
|                 raise AuthError(403, "You don't have permission to invite users")
 | |
|     elif Membership.JOIN == membership:
 | |
|         # Joins are valid iff caller == target and:
 | |
|         # * They are not banned.
 | |
|         # * They are accepting a previously sent invitation.
 | |
|         # * They are already joined (it's a NOOP).
 | |
|         # * The room is public.
 | |
|         # * The room is restricted and the user meets the allows rules.
 | |
|         if event.user_id != target_user_id:
 | |
|             raise AuthError(403, "Cannot force another user to join.")
 | |
|         elif target_banned:
 | |
|             raise AuthError(403, "You are banned from this room")
 | |
|         elif join_rule == JoinRules.PUBLIC:
 | |
|             pass
 | |
|         elif room_version.msc3083_join_rules and join_rule == JoinRules.RESTRICTED:
 | |
|             # This is the same as public, but the event must contain a reference
 | |
|             # to the server who authorised the join. If the event does not contain
 | |
|             # the proper content it is rejected.
 | |
|             #
 | |
|             # Note that if the caller is in the room or invited, then they do
 | |
|             # not need to meet the allow rules.
 | |
|             if not caller_in_room and not caller_invited:
 | |
|                 authorising_user = event.content.get(
 | |
|                     EventContentFields.AUTHORISING_USER
 | |
|                 )
 | |
| 
 | |
|                 if authorising_user is None:
 | |
|                     raise AuthError(403, "Join event is missing authorising user.")
 | |
| 
 | |
|                 # The authorising user must be in the room.
 | |
|                 key = (EventTypes.Member, authorising_user)
 | |
|                 member_event = auth_events.get(key)
 | |
|                 _check_joined_room(member_event, authorising_user, event.room_id)
 | |
| 
 | |
|                 authorising_user_level = get_user_power_level(
 | |
|                     authorising_user, auth_events
 | |
|                 )
 | |
|                 if authorising_user_level < invite_level:
 | |
|                     raise AuthError(403, "Join event authorised by invalid server.")
 | |
| 
 | |
|         elif join_rule == JoinRules.INVITE or (
 | |
|             room_version.msc2403_knocking and join_rule == JoinRules.KNOCK
 | |
|         ):
 | |
|             if not caller_in_room and not caller_invited:
 | |
|                 raise AuthError(403, "You are not invited to this room.")
 | |
|         else:
 | |
|             # TODO (erikj): may_join list
 | |
|             # TODO (erikj): private rooms
 | |
|             raise AuthError(403, "You are not allowed to join this room")
 | |
|     elif Membership.LEAVE == membership:
 | |
|         # TODO (erikj): Implement kicks.
 | |
|         if target_banned and user_level < ban_level:
 | |
|             raise AuthError(403, "You cannot unban user %s." % (target_user_id,))
 | |
|         elif target_user_id != event.user_id:
 | |
|             kick_level = get_named_level(auth_events, "kick", 50)
 | |
| 
 | |
|             if user_level < kick_level or user_level <= target_level:
 | |
|                 raise AuthError(403, "You cannot kick user %s." % target_user_id)
 | |
|     elif Membership.BAN == membership:
 | |
|         if user_level < ban_level or user_level <= target_level:
 | |
|             raise AuthError(403, "You don't have permission to ban")
 | |
|     elif room_version.msc2403_knocking and Membership.KNOCK == membership:
 | |
|         if join_rule != JoinRules.KNOCK:
 | |
|             raise AuthError(403, "You don't have permission to knock")
 | |
|         elif target_user_id != event.user_id:
 | |
|             raise AuthError(403, "You cannot knock for other users")
 | |
|         elif target_in_room:
 | |
|             raise AuthError(403, "You cannot knock on a room you are already in")
 | |
|         elif caller_invited:
 | |
|             raise AuthError(403, "You are already invited to this room")
 | |
|         elif target_banned:
 | |
|             raise AuthError(403, "You are banned from this room")
 | |
|     else:
 | |
|         raise AuthError(500, "Unknown membership %s" % membership)
 | |
| 
 | |
| 
 | |
| def _check_event_sender_in_room(
 | |
|     event: EventBase, auth_events: StateMap[EventBase]
 | |
| ) -> None:
 | |
|     key = (EventTypes.Member, event.user_id)
 | |
|     member_event = auth_events.get(key)
 | |
| 
 | |
|     _check_joined_room(member_event, event.user_id, event.room_id)
 | |
| 
 | |
| 
 | |
| def _check_joined_room(member: Optional[EventBase], user_id: str, room_id: str) -> None:
 | |
|     if not member or member.membership != Membership.JOIN:
 | |
|         raise AuthError(
 | |
|             403, "User %s not in room %s (%s)" % (user_id, room_id, repr(member))
 | |
|         )
 | |
| 
 | |
| 
 | |
| def get_send_level(
 | |
|     etype: str, state_key: Optional[str], power_levels_event: Optional[EventBase]
 | |
| ) -> int:
 | |
|     """Get the power level required to send an event of a given type
 | |
| 
 | |
|     The federation spec [1] refers to this as "Required Power Level".
 | |
| 
 | |
|     https://matrix.org/docs/spec/server_server/unstable.html#definitions
 | |
| 
 | |
|     Args:
 | |
|         etype: type of event
 | |
|         state_key: state_key of state event, or None if it is not
 | |
|             a state event.
 | |
|         power_levels_event: power levels event
 | |
|             in force at this point in the room
 | |
|     Returns:
 | |
|         power level required to send this event.
 | |
|     """
 | |
| 
 | |
|     if power_levels_event:
 | |
|         power_levels_content = power_levels_event.content
 | |
|     else:
 | |
|         power_levels_content = {}
 | |
| 
 | |
|     # see if we have a custom level for this event type
 | |
|     send_level = power_levels_content.get("events", {}).get(etype)
 | |
| 
 | |
|     # otherwise, fall back to the state_default/events_default.
 | |
|     if send_level is None:
 | |
|         if state_key is not None:
 | |
|             send_level = power_levels_content.get("state_default", 50)
 | |
|         else:
 | |
|             send_level = power_levels_content.get("events_default", 0)
 | |
| 
 | |
|     return int(send_level)
 | |
| 
 | |
| 
 | |
| def _can_send_event(event: EventBase, auth_events: StateMap[EventBase]) -> bool:
 | |
|     power_levels_event = get_power_level_event(auth_events)
 | |
| 
 | |
|     send_level = get_send_level(event.type, event.get("state_key"), power_levels_event)
 | |
|     user_level = get_user_power_level(event.user_id, auth_events)
 | |
| 
 | |
|     if user_level < send_level:
 | |
|         raise AuthError(
 | |
|             403,
 | |
|             "You don't have permission to post that to the room. "
 | |
|             + "user_level (%d) < send_level (%d)" % (user_level, send_level),
 | |
|         )
 | |
| 
 | |
|     # Check state_key
 | |
|     if hasattr(event, "state_key"):
 | |
|         if event.state_key.startswith("@"):
 | |
|             if event.state_key != event.user_id:
 | |
|                 raise AuthError(403, "You are not allowed to set others state")
 | |
| 
 | |
|     return True
 | |
| 
 | |
| 
 | |
| def check_redaction(
 | |
|     room_version_obj: RoomVersion,
 | |
|     event: EventBase,
 | |
|     auth_events: StateMap[EventBase],
 | |
| ) -> bool:
 | |
|     """Check whether the event sender is allowed to redact the target event.
 | |
| 
 | |
|     Returns:
 | |
|         True if the the sender is allowed to redact the target event if the
 | |
|         target event was created by them.
 | |
|         False if the sender is allowed to redact the target event with no
 | |
|         further checks.
 | |
| 
 | |
|     Raises:
 | |
|         AuthError if the event sender is definitely not allowed to redact
 | |
|         the target event.
 | |
|     """
 | |
|     user_level = get_user_power_level(event.user_id, auth_events)
 | |
| 
 | |
|     redact_level = get_named_level(auth_events, "redact", 50)
 | |
| 
 | |
|     if user_level >= redact_level:
 | |
|         return False
 | |
| 
 | |
|     if room_version_obj.event_format == EventFormatVersions.V1:
 | |
|         redacter_domain = get_domain_from_id(event.event_id)
 | |
|         if not isinstance(event.redacts, str):
 | |
|             return False
 | |
|         redactee_domain = get_domain_from_id(event.redacts)
 | |
|         if redacter_domain == redactee_domain:
 | |
|             return True
 | |
|     else:
 | |
|         event.internal_metadata.recheck_redaction = True
 | |
|         return True
 | |
| 
 | |
|     raise AuthError(403, "You don't have permission to redact events")
 | |
| 
 | |
| 
 | |
| def check_historical(
 | |
|     room_version_obj: RoomVersion,
 | |
|     event: EventBase,
 | |
|     auth_events: StateMap[EventBase],
 | |
| ) -> None:
 | |
|     """Check whether the event sender is allowed to send historical related
 | |
|     events like "insertion", "batch", and "marker".
 | |
| 
 | |
|     Returns:
 | |
|         None
 | |
| 
 | |
|     Raises:
 | |
|         AuthError if the event sender is not allowed to send historical related events
 | |
|         ("insertion", "batch", and "marker").
 | |
|     """
 | |
|     # Ignore the auth checks in room versions that do not support historical
 | |
|     # events
 | |
|     if not room_version_obj.msc2716_historical:
 | |
|         return
 | |
| 
 | |
|     user_level = get_user_power_level(event.user_id, auth_events)
 | |
| 
 | |
|     historical_level = get_named_level(auth_events, "historical", 100)
 | |
| 
 | |
|     if user_level < historical_level:
 | |
|         raise AuthError(
 | |
|             403,
 | |
|             'You don\'t have permission to send send historical related events ("insertion", "batch", and "marker")',
 | |
|         )
 | |
| 
 | |
| 
 | |
| def _check_power_levels(
 | |
|     room_version_obj: RoomVersion,
 | |
|     event: EventBase,
 | |
|     auth_events: StateMap[EventBase],
 | |
| ) -> None:
 | |
|     user_list = event.content.get("users", {})
 | |
|     # Validate users
 | |
|     for k, v in user_list.items():
 | |
|         try:
 | |
|             UserID.from_string(k)
 | |
|         except Exception:
 | |
|             raise SynapseError(400, "Not a valid user_id: %s" % (k,))
 | |
| 
 | |
|         try:
 | |
|             int(v)
 | |
|         except Exception:
 | |
|             raise SynapseError(400, "Not a valid power level: %s" % (v,))
 | |
| 
 | |
|     key = (event.type, event.state_key)
 | |
|     current_state = auth_events.get(key)
 | |
| 
 | |
|     if not current_state:
 | |
|         return
 | |
| 
 | |
|     user_level = get_user_power_level(event.user_id, auth_events)
 | |
| 
 | |
|     # Check other levels:
 | |
|     levels_to_check: List[Tuple[str, Optional[str]]] = [
 | |
|         ("users_default", None),
 | |
|         ("events_default", None),
 | |
|         ("state_default", None),
 | |
|         ("ban", None),
 | |
|         ("redact", None),
 | |
|         ("kick", None),
 | |
|         ("invite", None),
 | |
|     ]
 | |
| 
 | |
|     old_list = current_state.content.get("users", {})
 | |
|     for user in set(list(old_list) + list(user_list)):
 | |
|         levels_to_check.append((user, "users"))
 | |
| 
 | |
|     old_list = current_state.content.get("events", {})
 | |
|     new_list = event.content.get("events", {})
 | |
|     for ev_id in set(list(old_list) + list(new_list)):
 | |
|         levels_to_check.append((ev_id, "events"))
 | |
| 
 | |
|     # MSC2209 specifies these checks should also be done for the "notifications"
 | |
|     # key.
 | |
|     if room_version_obj.limit_notifications_power_levels:
 | |
|         old_list = current_state.content.get("notifications", {})
 | |
|         new_list = event.content.get("notifications", {})
 | |
|         for ev_id in set(list(old_list) + list(new_list)):
 | |
|             levels_to_check.append((ev_id, "notifications"))
 | |
| 
 | |
|     old_state = current_state.content
 | |
|     new_state = event.content
 | |
| 
 | |
|     for level_to_check, dir in levels_to_check:
 | |
|         old_loc = old_state
 | |
|         new_loc = new_state
 | |
|         if dir:
 | |
|             old_loc = old_loc.get(dir, {})
 | |
|             new_loc = new_loc.get(dir, {})
 | |
| 
 | |
|         if level_to_check in old_loc:
 | |
|             old_level: Optional[int] = int(old_loc[level_to_check])
 | |
|         else:
 | |
|             old_level = None
 | |
| 
 | |
|         if level_to_check in new_loc:
 | |
|             new_level: Optional[int] = int(new_loc[level_to_check])
 | |
|         else:
 | |
|             new_level = None
 | |
| 
 | |
|         if new_level is not None and old_level is not None:
 | |
|             if new_level == old_level:
 | |
|                 continue
 | |
| 
 | |
|         if dir == "users" and level_to_check != event.user_id:
 | |
|             if old_level == user_level:
 | |
|                 raise AuthError(
 | |
|                     403,
 | |
|                     "You don't have permission to remove ops level equal "
 | |
|                     "to your own",
 | |
|                 )
 | |
| 
 | |
|         # Check if the old and new levels are greater than the user level
 | |
|         # (if defined)
 | |
|         old_level_too_big = old_level is not None and old_level > user_level
 | |
|         new_level_too_big = new_level is not None and new_level > user_level
 | |
|         if old_level_too_big or new_level_too_big:
 | |
|             raise AuthError(
 | |
|                 403, "You don't have permission to add ops level greater than your own"
 | |
|             )
 | |
| 
 | |
| 
 | |
| def get_power_level_event(auth_events: StateMap[EventBase]) -> Optional[EventBase]:
 | |
|     return auth_events.get((EventTypes.PowerLevels, ""))
 | |
| 
 | |
| 
 | |
| def get_user_power_level(user_id: str, auth_events: StateMap[EventBase]) -> int:
 | |
|     """Get a user's power level
 | |
| 
 | |
|     Args:
 | |
|         user_id: user's id to look up in power_levels
 | |
|         auth_events:
 | |
|             state in force at this point in the room (or rather, a subset of
 | |
|             it including at least the create event and power levels event.
 | |
| 
 | |
|     Returns:
 | |
|         the user's power level in this room.
 | |
|     """
 | |
|     power_level_event = get_power_level_event(auth_events)
 | |
|     if power_level_event:
 | |
|         level = power_level_event.content.get("users", {}).get(user_id)
 | |
|         if level is None:
 | |
|             level = power_level_event.content.get("users_default", 0)
 | |
| 
 | |
|         if level is None:
 | |
|             return 0
 | |
|         else:
 | |
|             return int(level)
 | |
|     else:
 | |
|         # if there is no power levels event, the creator gets 100 and everyone
 | |
|         # else gets 0.
 | |
| 
 | |
|         # some things which call this don't pass the create event: hack around
 | |
|         # that.
 | |
|         key = (EventTypes.Create, "")
 | |
|         create_event = auth_events.get(key)
 | |
|         if create_event is not None and create_event.content["creator"] == user_id:
 | |
|             return 100
 | |
|         else:
 | |
|             return 0
 | |
| 
 | |
| 
 | |
| def get_named_level(auth_events: StateMap[EventBase], name: str, default: int) -> int:
 | |
|     power_level_event = get_power_level_event(auth_events)
 | |
| 
 | |
|     if not power_level_event:
 | |
|         return default
 | |
| 
 | |
|     level = power_level_event.content.get(name, None)
 | |
|     if level is not None:
 | |
|         return int(level)
 | |
|     else:
 | |
|         return default
 | |
| 
 | |
| 
 | |
| def _verify_third_party_invite(event: EventBase, auth_events: StateMap[EventBase]):
 | |
|     """
 | |
|     Validates that the invite event is authorized by a previous third-party invite.
 | |
| 
 | |
|     Checks that the public key, and keyserver, match those in the third party invite,
 | |
|     and that the invite event has a signature issued using that public key.
 | |
| 
 | |
|     Args:
 | |
|         event: The m.room.member join event being validated.
 | |
|         auth_events: All relevant previous context events which may be used
 | |
|             for authorization decisions.
 | |
| 
 | |
|     Return:
 | |
|         True if the event fulfills the expectations of a previous third party
 | |
|         invite event.
 | |
|     """
 | |
|     if "third_party_invite" not in event.content:
 | |
|         return False
 | |
|     if "signed" not in event.content["third_party_invite"]:
 | |
|         return False
 | |
|     signed = event.content["third_party_invite"]["signed"]
 | |
|     for key in {"mxid", "token"}:
 | |
|         if key not in signed:
 | |
|             return False
 | |
| 
 | |
|     token = signed["token"]
 | |
| 
 | |
|     invite_event = auth_events.get((EventTypes.ThirdPartyInvite, token))
 | |
|     if not invite_event:
 | |
|         return False
 | |
| 
 | |
|     if invite_event.sender != event.sender:
 | |
|         return False
 | |
| 
 | |
|     if event.user_id != invite_event.user_id:
 | |
|         return False
 | |
| 
 | |
|     if signed["mxid"] != event.state_key:
 | |
|         return False
 | |
|     if signed["token"] != token:
 | |
|         return False
 | |
| 
 | |
|     for public_key_object in get_public_keys(invite_event):
 | |
|         public_key = public_key_object["public_key"]
 | |
|         try:
 | |
|             for server, signature_block in signed["signatures"].items():
 | |
|                 for key_name in signature_block.keys():
 | |
|                     if not key_name.startswith("ed25519:"):
 | |
|                         continue
 | |
|                     verify_key = decode_verify_key_bytes(
 | |
|                         key_name, decode_base64(public_key)
 | |
|                     )
 | |
|                     verify_signed_json(signed, server, verify_key)
 | |
| 
 | |
|                     # We got the public key from the invite, so we know that the
 | |
|                     # correct server signed the signed bundle.
 | |
|                     # The caller is responsible for checking that the signing
 | |
|                     # server has not revoked that public key.
 | |
|                     return True
 | |
|         except (KeyError, SignatureVerifyException):
 | |
|             continue
 | |
|     return False
 | |
| 
 | |
| 
 | |
| def get_public_keys(invite_event: EventBase) -> List[Dict[str, Any]]:
 | |
|     public_keys = []
 | |
|     if "public_key" in invite_event.content:
 | |
|         o = {"public_key": invite_event.content["public_key"]}
 | |
|         if "key_validity_url" in invite_event.content:
 | |
|             o["key_validity_url"] = invite_event.content["key_validity_url"]
 | |
|         public_keys.append(o)
 | |
|     public_keys.extend(invite_event.content.get("public_keys", []))
 | |
|     return public_keys
 | |
| 
 | |
| 
 | |
| def auth_types_for_event(
 | |
|     room_version: RoomVersion, event: Union[EventBase, EventBuilder]
 | |
| ) -> Set[Tuple[str, str]]:
 | |
|     """Given an event, return a list of (EventType, StateKey) that may be
 | |
|     needed to auth the event. The returned list may be a superset of what
 | |
|     would actually be required depending on the full state of the room.
 | |
| 
 | |
|     Used to limit the number of events to fetch from the database to
 | |
|     actually auth the event.
 | |
|     """
 | |
|     if event.type == EventTypes.Create:
 | |
|         return set()
 | |
| 
 | |
|     auth_types = {
 | |
|         (EventTypes.PowerLevels, ""),
 | |
|         (EventTypes.Member, event.sender),
 | |
|         (EventTypes.Create, ""),
 | |
|     }
 | |
| 
 | |
|     if event.type == EventTypes.Member:
 | |
|         membership = event.content["membership"]
 | |
|         if membership in [Membership.JOIN, Membership.INVITE, Membership.KNOCK]:
 | |
|             auth_types.add((EventTypes.JoinRules, ""))
 | |
| 
 | |
|         auth_types.add((EventTypes.Member, event.state_key))
 | |
| 
 | |
|         if membership == Membership.INVITE:
 | |
|             if "third_party_invite" in event.content:
 | |
|                 key = (
 | |
|                     EventTypes.ThirdPartyInvite,
 | |
|                     event.content["third_party_invite"]["signed"]["token"],
 | |
|                 )
 | |
|                 auth_types.add(key)
 | |
| 
 | |
|         if room_version.msc3083_join_rules and membership == Membership.JOIN:
 | |
|             if EventContentFields.AUTHORISING_USER in event.content:
 | |
|                 key = (
 | |
|                     EventTypes.Member,
 | |
|                     event.content[EventContentFields.AUTHORISING_USER],
 | |
|                 )
 | |
|                 auth_types.add(key)
 | |
| 
 | |
|     return auth_types
 |