Merge pull request #6787 from matrix-org/rav/msc2260

Implement updated auth rules from MSC2260

changelog.d/6787.feature

@@ -0,0 +1 @@
+Implement updated authorization rules for aliases events, from [MSC2260](https://github.com/matrix-org/matrix-doc/pull/2260).

synapse/api/room_versions.py

@@ -57,6 +57,9 @@ class RoomVersion(object):
  state_res = attr.ib() # int; one of the StateResolutionVersions
  enforce_key_validity = attr.ib() # bool
 
+ # bool: before MSC2260, anyone was allowed to send an aliases event
+ special_case_aliases_auth = attr.ib(type=bool, default=False)
+
 
 class RoomVersions(object):
  V1 = RoomVersion(
@@ -65,34 +68,46 @@ class RoomVersions(object):
  EventFormatVersions.V1,
  StateResolutionVersions.V1,
  enforce_key_validity=False,
+ special_case_aliases_auth=True,
  )
  V2 = RoomVersion(
  "2",
  RoomDisposition.STABLE,
  EventFormatVersions.V1,
  StateResolutionVersions.V2,
  enforce_key_validity=False,
+ special_case_aliases_auth=True,
  )
  V3 = RoomVersion(
  "3",
  RoomDisposition.STABLE,
  EventFormatVersions.V2,
  StateResolutionVersions.V2,
  enforce_key_validity=False,
+ special_case_aliases_auth=True,
  )
  V4 = RoomVersion(
  "4",
  RoomDisposition.STABLE,
  EventFormatVersions.V3,
  StateResolutionVersions.V2,
  enforce_key_validity=False,
+ special_case_aliases_auth=True,
  )
  V5 = RoomVersion(
  "5",
  RoomDisposition.STABLE,
  EventFormatVersions.V3,
  StateResolutionVersions.V2,
  enforce_key_validity=True,
+ special_case_aliases_auth=True,
+ )
+ MSC2260_DEV = RoomVersion(
+ "org.matrix.msc2260",
+ RoomDisposition.UNSTABLE,
+ EventFormatVersions.V3,
+ StateResolutionVersions.V2,
+ enforce_key_validity=True,
  )
 
 
@@ -104,5 +119,6 @@ class RoomVersions(object):
  RoomVersions.V3,
  RoomVersions.V4,
  RoomVersions.V5,
+ RoomVersions.MSC2260_DEV,
  )
 } # type: Dict[str, RoomVersion]

synapse/event_auth.py

@@ -100,48 +100,62 @@ def check(
  if not event.signatures.get(event_id_domain):
  raise AuthError(403, "Event not signed by sending server")
 
+ # Implementation of https://matrix.org/docs/spec/rooms/v1#authorization-rules
+ #
+ # 1. If type is m.room.create:
  if event.type == EventTypes.Create:
+ # 1b. If the domain of the room_id does not match the domain of the sender,
+ # reject.
  sender_domain = get_domain_from_id(event.sender)
  room_id_domain = get_domain_from_id(event.room_id)
  if room_id_domain != sender_domain:
  raise AuthError(
  403, "Creation event's room_id domain does not match sender's"
  )
 
+ # 1c. If content.room_version is present and is not a recognised version, reject
  room_version_prop = event.content.get("room_version", "1")
  if room_version_prop not in KNOWN_ROOM_VERSIONS:
  raise AuthError(
  403,
  "room appears to have unsupported version %s" % (room_version_prop,),
  )
- # FIXME
+
  logger.debug("Allowing! %s", event)
  return
 
+ # 3. If event does not have a m.room.create in its auth_events, reject.
  creation_event = auth_events.get((EventTypes.Create, ""), None)
-
  if not creation_event:
  raise AuthError(403, "No create event in auth events")
 
+ # additional check for m.federate
  creating_domain = get_domain_from_id(event.room_id)
  originating_domain = get_domain_from_id(event.sender)
  if creating_domain != originating_domain:
  if not _can_federate(event, auth_events):
  raise AuthError(403, "This room has been marked as unfederatable.")
 
- # FIXME: Temp hack
+ # 4. If type is m.room.aliases
  if event.type == EventTypes.Aliases:
+ # 4a. If event has no state_key, reject
  if not event.is_state():
  raise AuthError(403, "Alias event must be a state event")
  if not event.state_key:
  raise AuthError(403, "Alias event must have non-empty state_key")
+
+ # 4b. If sender's domain doesn't matches [sic] state_key, reject
  sender_domain = get_domain_from_id(event.sender)
  if event.state_key != sender_domain:
  raise AuthError(
  403, "Alias event's state_key does not match sender's domain"
  )
- logger.debug("Allowing! %s", event)
- return
+
+ # 4c. Otherwise, allow.
+ # This is removed by https://github.com/matrix-org/matrix-doc/pull/2260
+ if room_version_obj.special_case_aliases_auth:
+ logger.debug("Allowing! %s", event)
+ return
 
  if logger.isEnabledFor(logging.DEBUG):
  logger.debug("Auth events: %s", [a.event_id for a in auth_events.values()])