mirror of https://github.com/watcha-fr/synapse
Erik Johnston
8 years ago
parent
7e6c2937c3
commit
8b2fa38256
@ -0,0 +1,641 @@ |
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# -*- 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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|
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import logging |
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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 verify_signed_json, SignatureVerifyException |
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from unpaddedbase64 import decode_base64 |
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|
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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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|
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def check(event, auth_events, do_sig_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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_check_size_limits(event) |
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|
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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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|
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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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|
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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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|
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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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|
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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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|
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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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|
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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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|
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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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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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|
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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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|
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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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|
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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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|
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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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|
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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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|
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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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|
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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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|
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|
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def _get_power_level_event(auth_events): |
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key = (EventTypes.PowerLevels, "", ) |
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return auth_events.get(key) |
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|
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|
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def get_user_power_level(user_id, auth_events): |
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power_level_event = _get_power_level_event(auth_events) |
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|
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if power_level_event: |
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level = power_level_event.content.get("users", {}).get(user_id) |
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if not level: |
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level = power_level_event.content.get("users_default", 0) |
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|
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if level is None: |
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return 0 |
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else: |
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return int(level) |
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else: |
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key = (EventTypes.Create, "", ) |
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create_event = auth_events.get(key) |
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if (create_event is not None and |
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create_event.content["creator"] == user_id): |
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return 100 |
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else: |
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return 0 |
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|
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|
||||
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 |
||||
Loading…
Reference in new issue