Add option to disable per-room profiles

synapse/config/server.py

 # -*- coding: utf-8 -*-
 # Copyright 2014-2016 OpenMarket Ltd
 # Copyright 2017-2018 New Vector Ltd
+# Copyright 2019 The Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -173,6 +174,10 @@ class ServerConfig(Config):
             "require_membership_for_aliases", True,
         )
 
+        # Whether to allow per-room membership profiles through the send of membership
+        # events with profile information that differ from the target's global profile.
+        self.allow_per_room_profiles = config.get("allow_per_room_profiles", True)
+
         self.listeners = []
         for listener in config.get("listeners", []):
             if not isinstance(listener.get("port", None), int):
@@ -566,6 +571,12 @@ class ServerConfig(Config):
         # Defaults to 'true'.
         #
         #require_membership_for_aliases: false
+
+        # Whether to allow per-room membership profiles through the send of membership
+        # events with profile information that differ from the target's global profile.
+        # Defaults to 'true'.
+        #
+        #allow_per_room_profiles: false
         """ % locals()
 
     def read_arguments(self, args):

synapse/handlers/room_member.py

 # -*- coding: utf-8 -*-
 # Copyright 2016 OpenMarket Ltd
 # Copyright 2018 New Vector Ltd
+# Copyright 2019 The Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -73,6 +74,7 @@ class RoomMemberHandler(object):
         self.spam_checker = hs.get_spam_checker()
         self._server_notices_mxid = self.config.server_notices_mxid
         self._enable_lookup = hs.config.enable_3pid_lookup
+        self.allow_per_room_profiles = self.config.allow_per_room_profiles
 
         # This is only used to get at ratelimit function, and
         # maybe_kick_guest_users. It's fine there are multiple of these as
@@ -357,6 +359,13 @@ class RoomMemberHandler(object):
             # later on.
             content = dict(content)
 
+        if not self.allow_per_room_profiles:
+            # Strip profile data, knowing that new profile data will be added to the
+            # event's content in event_creation_handler.create_event() using the target's
+            # global profile.
+            content.pop("displayname", None)
+            content.pop("avatar_url", None)
+
         effective_membership_state = action
         if action in ["kick", "unban"]:
             effective_membership_state = "leave"