mirror of
https://mau.dev/maunium/synapse.git
synced 2024-12-15 10:33:49 +01:00
678 lines
22 KiB
Python
678 lines
22 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2014 - 2016 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import logging
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from 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 verify_signed_json, SignatureVerifyException
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from unpaddedbase64 import decode_base64
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from synapse.api.constants import EventTypes, Membership, JoinRules
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from synapse.api.errors import AuthError, SynapseError, EventSizeError
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from synapse.types import UserID, get_domain_from_id
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logger = logging.getLogger(__name__)
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def check(event, auth_events, do_sig_check=True, do_size_check=True):
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""" Checks if this event is correctly authed.
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Args:
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event: the event being checked.
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auth_events (dict: event-key -> event): the existing room state.
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Returns:
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True if the auth checks pass.
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"""
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if do_size_check:
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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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if do_sig_check:
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sender_domain = get_domain_from_id(event.sender)
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event_id_domain = get_domain_from_id(event.event_id)
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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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# Check the event_id's 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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if auth_events is None:
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# Oh, we don't know what the state of the room was, so we
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# are trusting that this is allowed (at least for now)
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logger.warn("Trusting event: %s", event.event_id)
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return True
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if event.type == EventTypes.Create:
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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(
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403,
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"Creation event's room_id domain does not match sender's"
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)
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# FIXME
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return True
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creation_event = auth_events.get((EventTypes.Create, ""), None)
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if not creation_event:
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raise SynapseError(
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403,
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"Room %r does not exist" % (event.room_id,)
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)
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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_events):
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raise AuthError(
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403,
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"This room has been marked as unfederatable."
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)
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# FIXME: Temp hack
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if event.type == EventTypes.Aliases:
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if not event.is_state():
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raise AuthError(
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403,
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"Alias event must be a state event",
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)
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if not event.state_key:
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raise AuthError(
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403,
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"Alias event must have non-empty state_key"
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)
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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,
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"Alias event's state_key does not match sender's domain"
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)
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return True
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if logger.isEnabledFor(logging.DEBUG):
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logger.debug(
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"Auth events: %s",
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[a.event_id for a in auth_events.values()]
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)
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if event.type == EventTypes.Member:
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allowed = _is_membership_change_allowed(
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event, auth_events
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)
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if allowed:
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logger.debug("Allowing! %s", event)
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else:
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logger.debug("Denying! %s", event)
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return allowed
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_check_event_sender_in_room(event, auth_events)
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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_events)
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invite_level = _get_named_level(auth_events, "invite", 0)
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if user_level < invite_level:
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raise AuthError(
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403, (
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"You cannot issue a third party invite for %s." %
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(event.content.display_name,)
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)
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)
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else:
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return True
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_can_send_event(event, auth_events)
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if event.type == EventTypes.PowerLevels:
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_check_power_levels(event, auth_events)
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if event.type == EventTypes.Redaction:
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check_redaction(event, auth_events)
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logger.debug("Allowing! %s", event)
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def _check_size_limits(event):
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def too_big(field):
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raise EventSizeError("%s too large" % (field,))
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if len(event.user_id) > 255:
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too_big("user_id")
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if len(event.room_id) > 255:
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too_big("room_id")
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if event.is_state() and len(event.state_key) > 255:
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too_big("state_key")
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if len(event.type) > 255:
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too_big("type")
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if len(event.event_id) > 255:
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too_big("event_id")
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if len(encode_canonical_json(event.get_pdu_json())) > 65536:
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too_big("event")
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def _can_federate(event, auth_events):
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creation_event = auth_events.get((EventTypes.Create, ""))
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return creation_event.content.get("m.federate", True) is True
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def _is_membership_change_allowed(event, auth_events):
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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_events) == 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_events[0][0] == create.event_id:
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if create.content["creator"] == event.state_key:
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return True
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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(
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403,
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"This room has been marked as unfederatable."
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)
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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
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# get info about the target
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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
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target_banned = target and target.membership == Membership.BAN
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key = (EventTypes.JoinRules, "", )
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join_rule_event = auth_events.get(key)
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if join_rule_event:
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join_rule = join_rule_event.content.get(
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"join_rule", JoinRules.INVITE
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)
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else:
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join_rule = JoinRules.INVITE
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user_level = get_user_power_level(event.user_id, auth_events)
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target_level = get_user_power_level(
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target_user_id, auth_events
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)
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# FIXME (erikj): What should we do here as the default?
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ban_level = _get_named_level(auth_events, "ban", 50)
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logger.debug(
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"_is_membership_change_allowed: %s",
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{
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"caller_in_room": caller_in_room,
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"caller_invited": caller_invited,
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"target_banned": target_banned,
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"target_in_room": target_in_room,
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"membership": membership,
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"join_rule": join_rule,
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"target_user_id": target_user_id,
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"event.user_id": event.user_id,
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}
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)
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if Membership.INVITE == membership and "third_party_invite" in event.content:
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if not _verify_third_party_invite(event, auth_events):
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raise AuthError(403, "You are not invited to this room.")
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if target_banned:
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raise AuthError(
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403, "%s is banned from the room" % (target_user_id,)
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)
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return True
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if Membership.JOIN != membership:
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if (caller_invited
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and Membership.LEAVE == membership
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and target_user_id == event.user_id):
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return True
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if not caller_in_room: # caller isn't joined
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raise AuthError(
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403,
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"%s not in room %s." % (event.user_id, event.room_id,)
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)
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if Membership.INVITE == membership:
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# TODO (erikj): We should probably handle this more intelligently
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# PRIVATE join rules.
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# Invites are valid iff caller is in the room and target isn't.
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if target_banned:
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raise AuthError(
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403, "%s is banned from the room" % (target_user_id,)
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)
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elif target_in_room: # the target is already in the room.
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raise AuthError(403, "%s is already in the room." %
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target_user_id)
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else:
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invite_level = _get_named_level(auth_events, "invite", 0)
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if user_level < invite_level:
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raise AuthError(
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403, "You cannot invite user %s." % target_user_id
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)
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elif Membership.JOIN == membership:
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# Joins are valid iff caller == target and they were:
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# invited: They are accepting the invitation
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# joined: It's a NOOP
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if event.user_id != target_user_id:
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raise AuthError(403, "Cannot force another user to join.")
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elif target_banned:
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raise AuthError(403, "You are banned from this room")
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elif join_rule == JoinRules.PUBLIC:
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pass
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elif join_rule == JoinRules.INVITE:
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if not caller_in_room and not caller_invited:
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raise AuthError(403, "You are not invited to this room.")
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else:
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# TODO (erikj): may_join list
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# TODO (erikj): private rooms
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raise AuthError(403, "You are not allowed to join this room")
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elif Membership.LEAVE == membership:
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# TODO (erikj): Implement kicks.
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if target_banned and user_level < ban_level:
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raise AuthError(
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403, "You cannot unban user &s." % (target_user_id,)
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)
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elif target_user_id != event.user_id:
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kick_level = _get_named_level(auth_events, "kick", 50)
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if user_level < kick_level or user_level <= target_level:
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raise AuthError(
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403, "You cannot kick user %s." % target_user_id
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)
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elif Membership.BAN == membership:
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if user_level < ban_level or user_level <= target_level:
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raise AuthError(403, "You don't have permission to ban")
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else:
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raise AuthError(500, "Unknown membership %s" % membership)
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return True
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def _check_event_sender_in_room(event, auth_events):
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key = (EventTypes.Member, event.user_id, )
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member_event = auth_events.get(key)
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return _check_joined_room(
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member_event,
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event.user_id,
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event.room_id
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)
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def _check_joined_room(member, user_id, room_id):
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if not member or member.membership != Membership.JOIN:
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raise AuthError(403, "User %s not in room %s (%s)" % (
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user_id, room_id, repr(member)
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))
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def get_send_level(etype, state_key, auth_events):
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key = (EventTypes.PowerLevels, "", )
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send_level_event = auth_events.get(key)
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send_level = None
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if send_level_event:
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send_level = send_level_event.content.get("events", {}).get(
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etype
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)
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if send_level is None:
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if state_key is not None:
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send_level = send_level_event.content.get(
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"state_default", 50
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)
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else:
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send_level = send_level_event.content.get(
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"events_default", 0
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)
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if send_level:
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send_level = int(send_level)
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else:
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send_level = 0
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return send_level
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def _can_send_event(event, auth_events):
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send_level = get_send_level(
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event.type, event.get("state_key", None), auth_events
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)
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user_level = get_user_power_level(event.user_id, auth_events)
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if user_level < send_level:
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raise AuthError(
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403,
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"You don't have permission to post that to the room. " +
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"user_level (%d) < send_level (%d)" % (user_level, send_level)
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)
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# Check state_key
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if hasattr(event, "state_key"):
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if event.state_key.startswith("@"):
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if event.state_key != event.user_id:
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raise AuthError(
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403,
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"You are not allowed to set others state"
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)
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return True
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def check_redaction(event, auth_events):
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"""Check whether the event sender is allowed to redact the target event.
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Returns:
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True if the the sender is allowed to redact the target event if the
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target event was created by them.
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False if the sender is allowed to redact the target event with no
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further checks.
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Raises:
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AuthError if the event sender is definitely not allowed to redact
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the target event.
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"""
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user_level = get_user_power_level(event.user_id, auth_events)
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redact_level = _get_named_level(auth_events, "redact", 50)
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if user_level >= redact_level:
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return False
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redacter_domain = get_domain_from_id(event.event_id)
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redactee_domain = get_domain_from_id(event.redacts)
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if redacter_domain == redactee_domain:
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return True
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raise AuthError(
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403,
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"You don't have permission to redact events"
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)
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def _check_power_levels(event, auth_events):
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user_list = event.content.get("users", {})
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# Validate users
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for k, v in user_list.items():
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try:
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UserID.from_string(k)
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except:
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raise SynapseError(400, "Not a valid user_id: %s" % (k,))
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try:
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int(v)
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except:
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raise SynapseError(400, "Not a valid power level: %s" % (v,))
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key = (event.type, event.state_key, )
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current_state = auth_events.get(key)
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if not current_state:
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return
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user_level = get_user_power_level(event.user_id, auth_events)
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# Check other levels:
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levels_to_check = [
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("users_default", None),
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("events_default", None),
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("state_default", None),
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("ban", None),
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("redact", None),
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("kick", None),
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("invite", None),
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]
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old_list = current_state.content.get("users")
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for user in set(old_list.keys() + user_list.keys()):
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levels_to_check.append(
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(user, "users")
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)
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old_list = current_state.content.get("events")
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new_list = event.content.get("events")
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for ev_id in set(old_list.keys() + new_list.keys()):
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levels_to_check.append(
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(ev_id, "events")
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)
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old_state = current_state.content
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new_state = event.content
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for level_to_check, dir in levels_to_check:
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old_loc = old_state
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new_loc = new_state
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if dir:
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old_loc = old_loc.get(dir, {})
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new_loc = new_loc.get(dir, {})
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if level_to_check in old_loc:
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old_level = int(old_loc[level_to_check])
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else:
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old_level = None
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if level_to_check in new_loc:
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new_level = int(new_loc[level_to_check])
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else:
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new_level = None
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if new_level is not None and old_level is not None:
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if new_level == old_level:
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continue
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if dir == "users" and level_to_check != event.user_id:
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if old_level == user_level:
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raise AuthError(
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403,
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"You don't have permission to remove ops level equal "
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"to your own"
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)
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if old_level > user_level or new_level > user_level:
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raise AuthError(
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403,
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"You don't have permission to add ops level greater "
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"than your own"
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)
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def _get_power_level_event(auth_events):
|
|
key = (EventTypes.PowerLevels, "", )
|
|
return auth_events.get(key)
|
|
|
|
|
|
def get_user_power_level(user_id, auth_events):
|
|
power_level_event = _get_power_level_event(auth_events)
|
|
|
|
if power_level_event:
|
|
level = power_level_event.content.get("users", {}).get(user_id)
|
|
if not level:
|
|
level = power_level_event.content.get("users_default", 0)
|
|
|
|
if level is None:
|
|
return 0
|
|
else:
|
|
return int(level)
|
|
else:
|
|
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, name, default):
|
|
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, auth_events):
|
|
"""
|
|
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, encoded_signature in signature_block.items():
|
|
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):
|
|
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(event):
|
|
"""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 []
|
|
|
|
auth_types = []
|
|
|
|
auth_types.append((EventTypes.PowerLevels, "", ))
|
|
auth_types.append((EventTypes.Member, event.user_id, ))
|
|
auth_types.append((EventTypes.Create, "", ))
|
|
|
|
if event.type == EventTypes.Member:
|
|
membership = event.content["membership"]
|
|
if membership in [Membership.JOIN, Membership.INVITE]:
|
|
auth_types.append((EventTypes.JoinRules, "", ))
|
|
|
|
auth_types.append((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.append(key)
|
|
|
|
return auth_types
|