diff options
Diffstat (limited to 'synapse/event_auth.py')
| -rw-r--r-- | synapse/event_auth.py | 153 |
1 files changed, 92 insertions, 61 deletions
diff --git a/synapse/event_auth.py b/synapse/event_auth.py index 5d7c6fa858..eef354de6e 100644 --- a/synapse/event_auth.py +++ b/synapse/event_auth.py @@ -41,42 +41,112 @@ from synapse.types import StateMap, UserID, get_domain_from_id logger = logging.getLogger(__name__) -def check( - room_version_obj: RoomVersion, - event: EventBase, - auth_events: StateMap[EventBase], - do_sig_check: bool = True, - do_size_check: bool = True, +def validate_event_for_room_version( + room_version_obj: RoomVersion, event: EventBase ) -> None: - """Checks if this event is correctly authed. + """Ensure that the event complies with the limits, and has the right signatures + + NB: does not *validate* the signatures - it assumes that any signatures present + have already been checked. + + NB: it does not check that the event satisfies the auth rules (that is done in + check_auth_rules_for_event) - these tests are independent of the rest of the state + in the room. + + NB: This is used to check events that have been received over federation. As such, + it can only enforce the checks specified in the relevant room version, to avoid + a split-brain situation where some servers accept such events, and others reject + them. + + TODO: consider moving this into EventValidator Args: - room_version_obj: the version of the room - event: the event being checked. - auth_events: the existing room state. - do_sig_check: True if it should be verified that the sending server - signed the event. - do_size_check: True if the size of the event fields should be verified. + room_version_obj: the version of the room which contains this event + event: the event to be checked Raises: - AuthError if the checks fail - - Returns: - if the auth checks pass. + SynapseError if there is a problem with the event """ - assert isinstance(auth_events, dict) - - if do_size_check: - _check_size_limits(event) + _check_size_limits(event) if not hasattr(event, "room_id"): raise AuthError(500, "Event has no room_id: %s" % event) - room_id = event.room_id + # check that the event has the correct signatures + sender_domain = get_domain_from_id(event.sender) + + is_invite_via_3pid = ( + event.type == EventTypes.Member + and event.membership == Membership.INVITE + and "third_party_invite" in event.content + ) + + # Check the sender's domain has signed the event + if not event.signatures.get(sender_domain): + # We allow invites via 3pid to have a sender from a different + # HS, as the sender must match the sender of the original + # 3pid invite. This is checked further down with the + # other dedicated membership checks. + if not is_invite_via_3pid: + raise AuthError(403, "Event not signed by sender's server") + + if event.format_version in (EventFormatVersions.V1,): + # Only older room versions have event IDs to check. + event_id_domain = get_domain_from_id(event.event_id) + + # Check the origin domain has signed the event + if not event.signatures.get(event_id_domain): + raise AuthError(403, "Event not signed by sending server") + + is_invite_via_allow_rule = ( + room_version_obj.msc3083_join_rules + and event.type == EventTypes.Member + and event.membership == Membership.JOIN + and "join_authorised_via_users_server" in event.content + ) + if is_invite_via_allow_rule: + authoriser_domain = get_domain_from_id( + event.content["join_authorised_via_users_server"] + ) + if not event.signatures.get(authoriser_domain): + raise AuthError(403, "Event not signed by authorising server") + + +def check_auth_rules_for_event( + room_version_obj: RoomVersion, event: EventBase, auth_events: StateMap[EventBase] +) -> None: + """Check that an event complies with the auth rules + + Checks whether an event passes the auth rules with a given set of state events + + Assumes that we have already checked that the event is the right shape (it has + enough signatures, has a room ID, etc). In other words: + + - it's fine for use in state resolution, when we have already decided whether to + accept the event or not, and are now trying to decide whether it should make it + into the room state + + - when we're doing the initial event auth, it is only suitable in combination with + a bunch of other tests. + + Args: + room_version_obj: the version of the room + event: the event being checked. + auth_events: the room state to check the events against. + + Raises: + AuthError if the checks fail + """ + assert isinstance(auth_events, dict) # We need to ensure that the auth events are actually for the same room, to # stop people from using powers they've been granted in other rooms for # example. + # + # Arguably we don't need to do this when we're just doing state res, as presumably + # the state res algorithm isn't silly enough to give us events from different rooms. + # Still, it's easier to do it anyway. + room_id = event.room_id for auth_event in auth_events.values(): if auth_event.room_id != room_id: raise AuthError( @@ -86,45 +156,6 @@ def check( % (event.event_id, room_id, auth_event.event_id, auth_event.room_id), ) - if do_sig_check: - sender_domain = get_domain_from_id(event.sender) - - is_invite_via_3pid = ( - event.type == EventTypes.Member - and event.membership == Membership.INVITE - and "third_party_invite" in event.content - ) - - # Check the sender's domain has signed the event - if not event.signatures.get(sender_domain): - # We allow invites via 3pid to have a sender from a different - # HS, as the sender must match the sender of the original - # 3pid invite. This is checked further down with the - # other dedicated membership checks. - if not is_invite_via_3pid: - raise AuthError(403, "Event not signed by sender's server") - - if event.format_version in (EventFormatVersions.V1,): - # Only older room versions have event IDs to check. - event_id_domain = get_domain_from_id(event.event_id) - - # Check the origin domain has signed the event - if not event.signatures.get(event_id_domain): - raise AuthError(403, "Event not signed by sending server") - - is_invite_via_allow_rule = ( - room_version_obj.msc3083_join_rules - and event.type == EventTypes.Member - and event.membership == Membership.JOIN - and "join_authorised_via_users_server" in event.content - ) - if is_invite_via_allow_rule: - authoriser_domain = get_domain_from_id( - event.content["join_authorised_via_users_server"] - ) - if not event.signatures.get(authoriser_domain): - raise AuthError(403, "Event not signed by authorising server") - # Implementation of https://matrix.org/docs/spec/rooms/v1#authorization-rules # # 1. If type is m.room.create: |