diff options
Diffstat (limited to 'synapse/handlers/federation.py')
| -rw-r--r-- | synapse/handlers/federation.py | 109 |
1 files changed, 83 insertions, 26 deletions
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py index 080aca3d71..ae7e0d6da2 100644 --- a/synapse/handlers/federation.py +++ b/synapse/handlers/federation.py @@ -15,8 +15,14 @@ # limitations under the License. """Contains handlers for federation events.""" + +import httplib +import itertools +import logging + from signedjson.key import decode_verify_key_bytes from signedjson.sign import verify_signed_json +from twisted.internet import defer from unpaddedbase64 import decode_base64 from ._base import BaseHandler @@ -43,10 +49,6 @@ from synapse.util.retryutils import NotRetryingDestination from synapse.util.distributor import user_joined_room -from twisted.internet import defer - -import itertools -import logging logger = logging.getLogger(__name__) @@ -115,6 +117,19 @@ class FederationHandler(BaseHandler): logger.debug("Already seen pdu %s", pdu.event_id) return + # do some initial sanity-checking of the event. In particular, make + # sure it doesn't have hundreds of prev_events or auth_events, which + # could cause a huge state resolution or cascade of event fetches. + try: + self._sanity_check_event(pdu) + except SynapseError as err: + raise FederationError( + "ERROR", + err.code, + err.msg, + affected=pdu.event_id, + ) + # If we are currently in the process of joining this room, then we # queue up events for later processing. if pdu.room_id in self.room_queues: @@ -149,10 +164,6 @@ class FederationHandler(BaseHandler): auth_chain = [] - have_seen = yield self.store.have_events( - [ev for ev, _ in pdu.prev_events] - ) - fetch_state = False # Get missing pdus if necessary. @@ -168,7 +179,7 @@ class FederationHandler(BaseHandler): ) prevs = {e_id for e_id, _ in pdu.prev_events} - seen = set(have_seen.keys()) + seen = yield self.store.have_seen_events(prevs) if min_depth and pdu.depth < min_depth: # This is so that we don't notify the user about this @@ -196,8 +207,7 @@ class FederationHandler(BaseHandler): # Update the set of things we've seen after trying to # fetch the missing stuff - have_seen = yield self.store.have_events(prevs) - seen = set(have_seen.iterkeys()) + seen = yield self.store.have_seen_events(prevs) if not prevs - seen: logger.info( @@ -248,8 +258,7 @@ class FederationHandler(BaseHandler): min_depth (int): Minimum depth of events to return. """ # We recalculate seen, since it may have changed. - have_seen = yield self.store.have_events(prevs) - seen = set(have_seen.keys()) + seen = yield self.store.have_seen_events(prevs) if not prevs - seen: return @@ -361,9 +370,7 @@ class FederationHandler(BaseHandler): if auth_chain: event_ids |= {e.event_id for e in auth_chain} - seen_ids = set( - (yield self.store.have_events(event_ids)).keys() - ) + seen_ids = yield self.store.have_seen_events(event_ids) if state and auth_chain is not None: # If we have any state or auth_chain given to us by the replication @@ -527,9 +534,16 @@ class FederationHandler(BaseHandler): def backfill(self, dest, room_id, limit, extremities): """ Trigger a backfill request to `dest` for the given `room_id` - This will attempt to get more events from the remote. This may return - be successfull and still return no events if the other side has no new - events to offer. + This will attempt to get more events from the remote. If the other side + has no new events to offer, this will return an empty list. + + As the events are received, we check their signatures, and also do some + sanity-checking on them. If any of the backfilled events are invalid, + this method throws a SynapseError. + + TODO: make this more useful to distinguish failures of the remote + server from invalid events (there is probably no point in trying to + re-fetch invalid events from every other HS in the room.) """ if dest == self.server_name: raise SynapseError(400, "Can't backfill from self.") @@ -541,6 +555,16 @@ class FederationHandler(BaseHandler): extremities=extremities, ) + # ideally we'd sanity check the events here for excess prev_events etc, + # but it's hard to reject events at this point without completely + # breaking backfill in the same way that it is currently broken by + # events whose signature we cannot verify (#3121). + # + # So for now we accept the events anyway. #3124 tracks this. + # + # for ev in events: + # self._sanity_check_event(ev) + # Don't bother processing events we already have. seen_events = yield self.store.have_events_in_timeline( set(e.event_id for e in events) @@ -633,7 +657,7 @@ class FederationHandler(BaseHandler): failed_to_fetch = missing_auth - set(auth_events) - seen_events = yield self.store.have_events( + seen_events = yield self.store.have_seen_events( set(auth_events.keys()) | set(state_events.keys()) ) @@ -843,6 +867,38 @@ class FederationHandler(BaseHandler): defer.returnValue(False) + def _sanity_check_event(self, ev): + """ + Do some early sanity checks of a received event + + In particular, checks it doesn't have an excessive number of + prev_events or auth_events, which could cause a huge state resolution + or cascade of event fetches. + + Args: + ev (synapse.events.EventBase): event to be checked + + Returns: None + + Raises: + SynapseError if the event does not pass muster + """ + if len(ev.prev_events) > 20: + logger.warn("Rejecting event %s which has %i prev_events", + ev.event_id, len(ev.prev_events)) + raise SynapseError( + httplib.BAD_REQUEST, + "Too many prev_events", + ) + + if len(ev.auth_events) > 10: + logger.warn("Rejecting event %s which has %i auth_events", + ev.event_id, len(ev.auth_events)) + raise SynapseError( + httplib.BAD_REQUEST, + "Too many auth_events", + ) + @defer.inlineCallbacks def send_invite(self, target_host, event): """ Sends the invite to the remote server for signing. @@ -1736,7 +1792,8 @@ class FederationHandler(BaseHandler): event_key = None if event_auth_events - current_state: - have_events = yield self.store.have_events( + # TODO: can we use store.have_seen_events here instead? + have_events = yield self.store.get_seen_events_with_rejections( event_auth_events - current_state ) else: @@ -1759,12 +1816,12 @@ class FederationHandler(BaseHandler): origin, event.room_id, event.event_id ) - seen_remotes = yield self.store.have_events( + seen_remotes = yield self.store.have_seen_events( [e.event_id for e in remote_auth_chain] ) for e in remote_auth_chain: - if e.event_id in seen_remotes.keys(): + if e.event_id in seen_remotes: continue if e.event_id == event.event_id: @@ -1791,7 +1848,7 @@ class FederationHandler(BaseHandler): except AuthError: pass - have_events = yield self.store.have_events( + have_events = yield self.store.get_seen_events_with_rejections( [e_id for e_id, _ in event.auth_events] ) seen_events = set(have_events.keys()) @@ -1876,13 +1933,13 @@ class FederationHandler(BaseHandler): local_auth_chain, ) - seen_remotes = yield self.store.have_events( + seen_remotes = yield self.store.have_seen_events( [e.event_id for e in result["auth_chain"]] ) # 3. Process any remote auth chain events we haven't seen. for ev in result["auth_chain"]: - if ev.event_id in seen_remotes.keys(): + if ev.event_id in seen_remotes: continue if ev.event_id == event.event_id: |