1077 lines
38 KiB
Python
1077 lines
38 KiB
Python
# Copyright 2014 - 2016 OpenMarket Ltd
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# Copyright 2020 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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import logging
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import typing
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from typing import (
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Any,
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Collection,
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Dict,
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Iterable,
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List,
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Mapping,
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Optional,
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Set,
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Tuple,
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Union,
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)
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from canonicaljson import encode_canonical_json
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from signedjson.key import decode_verify_key_bytes
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from signedjson.sign import SignatureVerifyException, verify_signed_json
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from typing_extensions import Protocol
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from unpaddedbase64 import decode_base64
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from synapse.api.constants import (
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MAX_PDU_SIZE,
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EventContentFields,
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EventTypes,
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JoinRules,
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Membership,
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)
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from synapse.api.errors import (
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AuthError,
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Codes,
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EventSizeError,
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SynapseError,
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UnstableSpecAuthError,
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)
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from synapse.api.room_versions import (
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KNOWN_ROOM_VERSIONS,
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EventFormatVersions,
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RoomVersion,
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)
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from synapse.storage.databases.main.events_worker import EventRedactBehaviour
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from synapse.types import MutableStateMap, StateMap, UserID, get_domain_from_id
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if typing.TYPE_CHECKING:
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# conditional imports to avoid import cycle
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from synapse.events import EventBase
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from synapse.events.builder import EventBuilder
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logger = logging.getLogger(__name__)
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class _EventSourceStore(Protocol):
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async def get_events(
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self,
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event_ids: Collection[str],
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redact_behaviour: EventRedactBehaviour,
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get_prev_content: bool = False,
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allow_rejected: bool = False,
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) -> Dict[str, "EventBase"]:
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...
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def validate_event_for_room_version(event: "EventBase") -> None:
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"""Ensure that the event complies with the limits, and has the right signatures
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NB: does not *validate* the signatures - it assumes that any signatures present
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have already been checked.
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NB: it does not check that the event satisfies the auth rules (that is done in
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check_auth_rules_for_event) - these tests are independent of the rest of the state
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in the room.
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NB: This is used to check events that have been received over federation. As such,
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it can only enforce the checks specified in the relevant room version, to avoid
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a split-brain situation where some servers accept such events, and others reject
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them. See also EventValidator, which contains extra checks which are applied only to
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locally-generated events.
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Args:
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event: the event to be checked
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Raises:
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SynapseError if there is a problem with the event
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"""
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_check_size_limits(event)
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if not hasattr(event, "room_id"):
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raise AuthError(500, "Event has no room_id: %s" % event)
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# check that the event has the correct signatures
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sender_domain = get_domain_from_id(event.sender)
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is_invite_via_3pid = (
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event.type == EventTypes.Member
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and event.membership == Membership.INVITE
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and "third_party_invite" in event.content
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)
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# Check the sender's domain has signed the event
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if not event.signatures.get(sender_domain):
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# We allow invites via 3pid to have a sender from a different
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# HS, as the sender must match the sender of the original
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# 3pid invite. This is checked further down with the
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# other dedicated membership checks.
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if not is_invite_via_3pid:
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raise AuthError(403, "Event not signed by sender's server")
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if event.format_version in (EventFormatVersions.ROOM_V1_V2,):
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# Only older room versions have event IDs to check.
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event_id_domain = get_domain_from_id(event.event_id)
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# Check the origin domain has signed the event
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if not event.signatures.get(event_id_domain):
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raise AuthError(403, "Event not signed by sending server")
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is_invite_via_allow_rule = (
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event.room_version.msc3083_join_rules
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and event.type == EventTypes.Member
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and event.membership == Membership.JOIN
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and EventContentFields.AUTHORISING_USER in event.content
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)
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if is_invite_via_allow_rule:
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authoriser_domain = get_domain_from_id(
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event.content[EventContentFields.AUTHORISING_USER]
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)
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if not event.signatures.get(authoriser_domain):
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raise AuthError(403, "Event not signed by authorising server")
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async def check_state_independent_auth_rules(
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store: _EventSourceStore,
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event: "EventBase",
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batched_auth_events: Optional[Mapping[str, "EventBase"]] = None,
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) -> None:
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"""Check that an event complies with auth rules that are independent of room state
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Runs through the first few auth rules, which are independent of room state. (Which
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means that we only need to them once for each received event)
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Args:
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store: the datastore; used to fetch the auth events for validation
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event: the event being checked.
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batched_auth_events: if the event being authed is part of a batch, any events
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from the same batch that may be necessary to auth the current event
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Raises:
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AuthError if the checks fail
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"""
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# Implementation of https://spec.matrix.org/v1.2/rooms/v9/#authorization-rules
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# 1. If type is m.room.create:
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if event.type == EventTypes.Create:
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_check_create(event)
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# 1.5 Otherwise, allow
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return
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# 2. Reject if event has auth_events that: ...
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auth_events = await store.get_events(
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event.auth_event_ids(),
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redact_behaviour=EventRedactBehaviour.as_is,
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allow_rejected=True,
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)
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if batched_auth_events:
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auth_events.update(batched_auth_events)
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room_id = event.room_id
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auth_dict: MutableStateMap[str] = {}
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expected_auth_types = auth_types_for_event(event.room_version, event)
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for auth_event_id in event.auth_event_ids():
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auth_event = auth_events.get(auth_event_id)
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# we should have all the auth events by now, so if we do not, that suggests
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# a synapse programming error
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if auth_event is None:
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raise RuntimeError(
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f"Event {event.event_id} has unknown auth event {auth_event_id}"
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)
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# We need to ensure that the auth events are actually for the same room, to
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# stop people from using powers they've been granted in other rooms for
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# example.
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if auth_event.room_id != room_id:
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raise AuthError(
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403,
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"During auth for event %s in room %s, found event %s in the state "
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"which is in room %s"
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% (event.event_id, room_id, auth_event_id, auth_event.room_id),
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)
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k = (auth_event.type, auth_event.state_key)
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# 2.1 ... have duplicate entries for a given type and state_key pair
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if k in auth_dict:
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raise AuthError(
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403,
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f"Event {event.event_id} has duplicate auth_events for {k}: {auth_dict[k]} and {auth_event_id}",
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)
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# 2.2 ... have entries whose type and state_key don’t match those specified by
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# the auth events selection algorithm described in the server
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# specification.
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if k not in expected_auth_types:
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raise AuthError(
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403,
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f"Event {event.event_id} has unexpected auth_event for {k}: {auth_event_id}",
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)
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# We also need to check that the auth event itself is not rejected.
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if auth_event.rejected_reason:
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raise AuthError(
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403,
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"During auth for event %s: found rejected event %s in the state"
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% (event.event_id, auth_event.event_id),
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)
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auth_dict[k] = auth_event_id
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# 3. If event does not have a m.room.create in its auth_events, reject.
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creation_event = auth_dict.get((EventTypes.Create, ""), None)
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if not creation_event:
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raise AuthError(403, "No create event in auth events")
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def check_state_dependent_auth_rules(
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event: "EventBase",
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auth_events: Iterable["EventBase"],
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) -> None:
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"""Check that an event complies with auth rules that depend on room state
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Runs through the parts of the auth rules that check an event against bits of room
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state.
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Note:
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- it's fine for use in state resolution, when we have already decided whether to
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accept the event or not, and are now trying to decide whether it should make it
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into the room state
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- when we're doing the initial event auth, it is only suitable in combination with
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a bunch of other tests (including, but not limited to, check_state_independent_auth_rules).
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Args:
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event: the event being checked.
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auth_events: the room state to check the events against.
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Raises:
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AuthError if the checks fail
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"""
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# there are no state-dependent auth rules for create events.
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if event.type == EventTypes.Create:
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logger.debug("Allowing! %s", event)
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return
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auth_dict = {(e.type, e.state_key): e for e in auth_events}
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# additional check for m.federate
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creating_domain = get_domain_from_id(event.room_id)
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originating_domain = get_domain_from_id(event.sender)
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if creating_domain != originating_domain:
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if not _can_federate(event, auth_dict):
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raise AuthError(403, "This room has been marked as unfederatable.")
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# 4. If type is m.room.aliases
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if (
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event.type == EventTypes.Aliases
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and event.room_version.special_case_aliases_auth
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):
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# 4a. If event has no state_key, reject
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if not event.is_state():
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raise AuthError(403, "Alias event must be a state event")
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if not event.state_key:
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raise AuthError(403, "Alias event must have non-empty state_key")
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# 4b. If sender's domain doesn't matches [sic] state_key, reject
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sender_domain = get_domain_from_id(event.sender)
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if event.state_key != sender_domain:
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raise AuthError(
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403, "Alias event's state_key does not match sender's domain"
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)
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# 4c. Otherwise, allow.
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logger.debug("Allowing! %s", event)
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return
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# 5. If type is m.room.membership
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if event.type == EventTypes.Member:
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_is_membership_change_allowed(event.room_version, event, auth_dict)
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logger.debug("Allowing! %s", event)
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return
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_check_event_sender_in_room(event, auth_dict)
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# Special case to allow m.room.third_party_invite events wherever
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# a user is allowed to issue invites. Fixes
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# https://github.com/vector-im/vector-web/issues/1208 hopefully
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if event.type == EventTypes.ThirdPartyInvite:
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user_level = get_user_power_level(event.user_id, auth_dict)
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invite_level = get_named_level(auth_dict, "invite", 0)
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if user_level < invite_level:
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raise UnstableSpecAuthError(
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403,
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"You don't have permission to invite users",
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errcode=Codes.INSUFFICIENT_POWER,
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)
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else:
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logger.debug("Allowing! %s", event)
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return
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_can_send_event(event, auth_dict)
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if event.type == EventTypes.PowerLevels:
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_check_power_levels(event.room_version, event, auth_dict)
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if event.type == EventTypes.Redaction:
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check_redaction(event.room_version, event, auth_dict)
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if (
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event.type == EventTypes.MSC2716_INSERTION
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or event.type == EventTypes.MSC2716_BATCH
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or event.type == EventTypes.MSC2716_MARKER
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):
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check_historical(event.room_version, event, auth_dict)
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logger.debug("Allowing! %s", event)
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def _check_size_limits(event: "EventBase") -> None:
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if len(event.user_id.encode("utf-8")) > 255:
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raise EventSizeError("'user_id' too large")
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if len(event.room_id.encode("utf-8")) > 255:
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raise EventSizeError("'room_id' too large")
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if event.is_state() and len(event.state_key.encode("utf-8")) > 255:
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raise EventSizeError("'state_key' too large")
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if len(event.type.encode("utf-8")) > 255:
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raise EventSizeError("'type' too large")
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if len(event.event_id.encode("utf-8")) > 255:
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raise EventSizeError("'event_id' too large")
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if len(encode_canonical_json(event.get_pdu_json())) > MAX_PDU_SIZE:
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raise EventSizeError("event too large")
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def _check_create(event: "EventBase") -> None:
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"""Implementation of the auth rules for m.room.create events
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Args:
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event: The `m.room.create` event to be checked
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Raises:
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AuthError if the event does not pass the auth rules
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"""
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assert event.type == EventTypes.Create
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# 1.1 If it has any previous events, reject.
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if event.prev_event_ids():
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raise AuthError(403, "Create event has prev events")
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# 1.2 If the domain of the room_id does not match the domain of the sender,
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# reject.
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sender_domain = get_domain_from_id(event.sender)
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room_id_domain = get_domain_from_id(event.room_id)
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if room_id_domain != sender_domain:
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raise AuthError(403, "Creation event's room_id domain does not match sender's")
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# 1.3 If content.room_version is present and is not a recognised version, reject
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room_version_prop = event.content.get("room_version", "1")
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if room_version_prop not in KNOWN_ROOM_VERSIONS:
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raise AuthError(
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403,
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"room appears to have unsupported version %s" % (room_version_prop,),
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)
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# 1.4 If content has no creator field, reject.
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if EventContentFields.ROOM_CREATOR not in event.content:
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raise AuthError(403, "Create event lacks a 'creator' property")
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def _can_federate(event: "EventBase", auth_events: StateMap["EventBase"]) -> bool:
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creation_event = auth_events.get((EventTypes.Create, ""))
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# There should always be a creation event, but if not don't federate.
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if not creation_event:
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return False
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return creation_event.content.get(EventContentFields.FEDERATE, True) is True
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def _is_membership_change_allowed(
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room_version: RoomVersion, event: "EventBase", auth_events: StateMap["EventBase"]
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) -> None:
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"""
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Confirms that the event which changes membership is an allowed change.
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||
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Args:
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room_version: The version of the room.
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event: The event to check.
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auth_events: The current auth events of the room.
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Raises:
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AuthError if the event is not allowed.
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"""
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membership = event.content["membership"]
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# Check if this is the room creator joining:
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if len(event.prev_event_ids()) == 1 and Membership.JOIN == membership:
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# Get room creation event:
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key = (EventTypes.Create, "")
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create = auth_events.get(key)
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if create and event.prev_event_ids()[0] == create.event_id:
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if create.content["creator"] == event.state_key:
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return
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target_user_id = event.state_key
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creating_domain = get_domain_from_id(event.room_id)
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target_domain = get_domain_from_id(target_user_id)
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if creating_domain != target_domain:
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if not _can_federate(event, auth_events):
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||
raise AuthError(403, "This room has been marked as unfederatable.")
|
||
|
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# get info about the caller
|
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key = (EventTypes.Member, event.user_id)
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caller = auth_events.get(key)
|
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caller_in_room = caller and caller.membership == Membership.JOIN
|
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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)
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||
target = auth_events.get(key)
|
||
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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:
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||
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.
|
||
# Note that the room version check for knocking is done implicitly by `caller_knocked`
|
||
# and the ability to set a membership of `knock` in the first place.
|
||
if Membership.JOIN != membership 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 UnstableSpecAuthError(
|
||
403,
|
||
"%s not in room %s." % (event.user_id, event.room_id),
|
||
errcode=Codes.NOT_JOINED,
|
||
)
|
||
|
||
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 UnstableSpecAuthError(
|
||
403,
|
||
"%s is already in the room." % target_user_id,
|
||
errcode=Codes.ALREADY_JOINED,
|
||
)
|
||
else:
|
||
if user_level < invite_level:
|
||
raise UnstableSpecAuthError(
|
||
403,
|
||
"You don't have permission to invite users",
|
||
errcode=Codes.INSUFFICIENT_POWER,
|
||
)
|
||
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
|
||
) or (
|
||
room_version.msc3787_knock_restricted_join_rule
|
||
and join_rule == JoinRules.KNOCK_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)
|
||
or (
|
||
room_version.msc3787_knock_restricted_join_rule
|
||
and join_rule == JoinRules.KNOCK_RESTRICTED
|
||
)
|
||
):
|
||
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 UnstableSpecAuthError(
|
||
403,
|
||
"You cannot unban user %s." % (target_user_id,),
|
||
errcode=Codes.INSUFFICIENT_POWER,
|
||
)
|
||
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 UnstableSpecAuthError(
|
||
403,
|
||
"You cannot kick user %s." % target_user_id,
|
||
errcode=Codes.INSUFFICIENT_POWER,
|
||
)
|
||
elif Membership.BAN == membership:
|
||
if user_level < ban_level or user_level <= target_level:
|
||
raise UnstableSpecAuthError(
|
||
403,
|
||
"You don't have permission to ban",
|
||
errcode=Codes.INSUFFICIENT_POWER,
|
||
)
|
||
elif room_version.msc2403_knocking and Membership.KNOCK == membership:
|
||
if join_rule != JoinRules.KNOCK and (
|
||
not room_version.msc3787_knock_restricted_join_rule
|
||
or join_rule != JoinRules.KNOCK_RESTRICTED
|
||
):
|
||
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 UnstableSpecAuthError(
|
||
403,
|
||
"You cannot knock on a room you are already in",
|
||
errcode=Codes.ALREADY_JOINED,
|
||
)
|
||
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 UnstableSpecAuthError(
|
||
403,
|
||
"You don't have permission to post that to the room. "
|
||
+ "user_level (%d) < send_level (%d)" % (user_level, send_level),
|
||
errcode=Codes.INSUFFICIENT_POWER,
|
||
)
|
||
|
||
# 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.ROOM_V1_V2:
|
||
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 UnstableSpecAuthError(
|
||
403,
|
||
'You don\'t have permission to send send historical related events ("insertion", "batch", and "marker")',
|
||
errcode=Codes.INSUFFICIENT_POWER,
|
||
)
|
||
|
||
|
||
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,))
|
||
|
||
# Reject events with stringy power levels if required by room version
|
||
if (
|
||
event.type == EventTypes.PowerLevels
|
||
and room_version_obj.msc3667_int_only_power_levels
|
||
):
|
||
for k, v in event.content.items():
|
||
if k in {
|
||
"users_default",
|
||
"events_default",
|
||
"state_default",
|
||
"ban",
|
||
"redact",
|
||
"kick",
|
||
"invite",
|
||
}:
|
||
if not isinstance(v, int):
|
||
raise SynapseError(400, f"{v!r} must be an integer.")
|
||
if k in {"events", "notifications", "users"}:
|
||
if not isinstance(v, dict) or not all(
|
||
isinstance(v, int) for v in v.values()
|
||
):
|
||
raise SynapseError(
|
||
400,
|
||
f"{v!r} must be a dict wherein all the values are integers.",
|
||
)
|
||
|
||
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"]
|
||
) -> bool:
|
||
"""
|
||
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
|