Validation for events/rooms in fed requests

When we get a federation request which refers to an event id, make sure that
said event is in the room the caller claims it is in.

(patch supplied by @turt2live)

1 files changed, 34 insertions, 1 deletions

diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py

index 20fb46fc89..12eeb7c4cd 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -1349,6 +1349,9 @@ class FederationHandler(BaseHandler):
     def get_state_for_pdu(self, room_id, event_id):
         """Returns the state at the event. i.e. not including said event.
         """
+
+        yield self._verify_events_in_room([event_id], room_id)
+
         state_groups = yield self.store.get_state_groups(
             room_id, [event_id]
         )
@@ -1391,6 +1394,9 @@ class FederationHandler(BaseHandler):
     def get_state_ids_for_pdu(self, room_id, event_id):
         """Returns the state at the event. i.e. not including said event.
         """
+
+        yield self._verify_events_in_room([event_id], room_id)
+
         state_groups = yield self.store.get_state_groups_ids(
             room_id, [event_id]
         )
@@ -1420,6 +1426,8 @@ class FederationHandler(BaseHandler):
         if not in_room:
             raise AuthError(403, "Host not in room.")
 
+        yield self._verify_events_in_room(pdu_list, room_id)
+
         events = yield self.store.get_backfill_events(
             room_id,
             pdu_list,
@@ -1706,8 +1714,17 @@ class FederationHandler(BaseHandler):
         defer.returnValue(context)
 
     @defer.inlineCallbacks
-    def on_query_auth(self, origin, event_id, remote_auth_chain, rejects,
+    def on_query_auth(self, origin, event_id, room_id, remote_auth_chain, rejects,
                       missing):
+        in_room = yield self.auth.check_host_in_room(
+            room_id,
+            origin
+        )
+        if not in_room:
+            raise AuthError(403, "Host not in room.")
+
+        yield self._verify_events_in_room([event_id], room_id)
+
         # Just go through and process each event in `remote_auth_chain`. We
         # don't want to fall into the trap of `missing` being wrong.
         for e in remote_auth_chain:
@@ -2368,3 +2385,19 @@ class FederationHandler(BaseHandler):
             )
         if "valid" not in response or not response["valid"]:
             raise AuthError(403, "Third party certificate was invalid")
+
+    @defer.inlineCallbacks
+    def _verify_events_in_room(self, pdu_ids, room_id):
+        """Checks whether the given PDU IDs are in the given room or not.
+
+        Args:
+            pdu_ids (list): list of PDU IDs
+            room_id (str): the room ID that the PDUs should be in
+
+        Raises:
+            AuthError: if one or more of the PDUs does not belong to the
+                given room.
+        """
+        room_ids = yield self.store.get_room_ids_for_events(pdu_ids)
+        if len(room_ids) != 1 or room_ids[0] != room_id:
+            raise AuthError(403, "Events must belong to the given room")