From 7765bf398996002ee461904915de9d8bc2ea951a Mon Sep 17 00:00:00 2001 From: Patrick Cloke Date: Thu, 6 Feb 2020 13:25:24 -0500 Subject: [PATCH] Limit the number of events that can be requested when backfilling events (#6864) Limit the maximum number of events requested when backfilling events. --- changelog.d/6864.misc | 1 + synapse/handlers/federation.py | 4 ++++ 2 files changed, 5 insertions(+) create mode 100644 changelog.d/6864.misc diff --git a/changelog.d/6864.misc b/changelog.d/6864.misc new file mode 100644 index 0000000000..d24eb68460 --- /dev/null +++ b/changelog.d/6864.misc @@ -0,0 +1 @@ +Limit the number of events that can be requested by the backfill federation API to 100. diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py index 10e8b6ea4c..eb20ef4aec 100644 --- a/synapse/handlers/federation.py +++ b/synapse/handlers/federation.py @@ -1788,6 +1788,9 @@ class FederationHandler(BaseHandler): if not in_room: raise AuthError(403, "Host not in room.") + # Synapse asks for 100 events per backfill request. Do not allow more. + limit = min(limit, 100) + events = yield self.store.get_backfill_events(room_id, pdu_list, limit) events = yield filter_events_for_server(self.storage, origin, events) @@ -2168,6 +2171,7 @@ class FederationHandler(BaseHandler): if not in_room: raise AuthError(403, "Host not in room.") + # Only allow up to 20 events to be retrieved per request. limit = min(limit, 20) missing_events = await self.store.get_missing_events(