From 5705ecaec6b7a85c152691c79a4fa3526792a3eb Mon Sep 17 00:00:00 2001 From: Brendan Abolivier Date: Wed, 2 Oct 2019 11:16:38 +0100 Subject: [PATCH 1/9] Don't 500 code when trying to exchange a revoked 3PID invite While this is not documented in the spec (but should be), Riot (and other clients) revoke 3PID invites by sending a m.room.third_party_invite event with an empty ({}) content to the room's state. When the invited 3PID gets associated with a MXID, the identity server (which doesn't know about revocations) sends down to the MXID's homeserver all of the undelivered invites it has for this 3PID. The homeserver then tries to talk to the inviting homeserver in order to exchange these invite for m.room.member events. When one of the invite is revoked, the inviting homeserver responds with a 500 error because it tries to extract a 'display_name' property from the content, which is empty. This might cause the invited server to consider that the server is down and not try to exchange other, valid invites (or at least delay it). This fix handles the case of revoked invites by avoiding trying to fetch a 'display_name' from the original invite's content, and letting the m.room.member event fail the auth rules (because, since the original invite's content is empty, it doesn't have public keys), which results in sending a 403 with the correct error message to the invited server. --- synapse/handlers/federation.py | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py index f72b81d41..a3d7739ea 100644 --- a/synapse/handlers/federation.py +++ b/synapse/handlers/federation.py @@ -2599,8 +2599,19 @@ class FederationHandler(BaseHandler): original_invite_id, allow_none=True ) if original_invite: - display_name = original_invite.content["display_name"] - event_dict["content"]["third_party_invite"]["display_name"] = display_name + # If the m.room.third_party_invite event's content is empty, it means the + # invite has been revoked. + if original_invite.content: + display_name = original_invite.content["display_name"] + event_dict["content"]["third_party_invite"]["display_name"] = display_name + else: + # Don't discard or raise an error here because that's not the right place + # to do auth checks. The auth check will fail on this invite because we + # won't be able to fetch public keys from the m.room.third_party_invite + # event's content (because it's empty). + logger.info( + "Found invite event for third_party_invite but it has been revoked" + ) else: logger.info( "Could not find invite event for third_party_invite: %r", event_dict From 972c9f65d7ddf94ce024b57397d651d184cb2d26 Mon Sep 17 00:00:00 2001 From: Brendan Abolivier Date: Wed, 2 Oct 2019 12:17:46 +0100 Subject: [PATCH 2/9] Lint --- synapse/handlers/federation.py | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py index a3d7739ea..75d79bb8e 100644 --- a/synapse/handlers/federation.py +++ b/synapse/handlers/federation.py @@ -2603,7 +2603,9 @@ class FederationHandler(BaseHandler): # invite has been revoked. if original_invite.content: display_name = original_invite.content["display_name"] - event_dict["content"]["third_party_invite"]["display_name"] = display_name + event_dict["content"]["third_party_invite"][ + "display_name" + ] = display_name else: # Don't discard or raise an error here because that's not the right place # to do auth checks. The auth check will fail on this invite because we From 24efea338d8643ee15f03b30c080a53320926ee8 Mon Sep 17 00:00:00 2001 From: Brendan Abolivier Date: Wed, 2 Oct 2019 12:20:03 +0100 Subject: [PATCH 3/9] Changelog --- changelog.d/6147.bugfix | 1 + 1 file changed, 1 insertion(+) create mode 100644 changelog.d/6147.bugfix diff --git a/changelog.d/6147.bugfix b/changelog.d/6147.bugfix new file mode 100644 index 000000000..b0f936d28 --- /dev/null +++ b/changelog.d/6147.bugfix @@ -0,0 +1 @@ +Don't 500 when trying to exchange a revoked 3PID invite. From 6527fa18c1e6f9bcb22318916b5e9534c91c84c1 Mon Sep 17 00:00:00 2001 From: Brendan Abolivier Date: Wed, 2 Oct 2019 14:44:58 +0100 Subject: [PATCH 4/9] Add test case --- synapse/handlers/federation.py | 2 +- tests/handlers/test_federation.py | 83 +++++++++++++++++++++++++++++++ 2 files changed, 84 insertions(+), 1 deletion(-) create mode 100644 tests/handlers/test_federation.py diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py index 75d79bb8e..91f3a6929 100644 --- a/synapse/handlers/federation.py +++ b/synapse/handlers/federation.py @@ -2570,7 +2570,7 @@ class FederationHandler(BaseHandler): ) try: - self.auth.check_from_context(room_version, event, context) + yield self.auth.check_from_context(room_version, event, context) except AuthError as e: logger.warn("Denying third party invite %r because %s", event, e) raise e diff --git a/tests/handlers/test_federation.py b/tests/handlers/test_federation.py new file mode 100644 index 000000000..20416a014 --- /dev/null +++ b/tests/handlers/test_federation.py @@ -0,0 +1,83 @@ +# -*- coding: utf-8 -*- +# 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. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. +from synapse.api.constants import EventTypes +from synapse.api.errors import AuthError, Codes +from synapse.rest import admin +from synapse.rest.client.v1 import login, room + +from tests import unittest + + +class FederationTestCase(unittest.HomeserverTestCase): + servlets = [ + admin.register_servlets, + login.register_servlets, + room.register_servlets, + ] + + def make_homeserver(self, reactor, clock): + hs = self.setup_test_homeserver(http_client=None) + self.handler = hs.get_handlers().federation_handler + self.store = hs.get_datastore() + return hs + + def test_exchange_revoked_invite(self): + user_id = self.register_user("kermit", "test") + tok = self.login("kermit", "test") + + room_id = self.helper.create_room_as( + room_creator=user_id, tok=tok + ) + + # Send a 3PID invite event with an empty body so it's considered as a revoked one. + invite_token = "sometoken" + self.helper.send_state( + room_id=room_id, + event_type=EventTypes.ThirdPartyInvite, + state_key=invite_token, + body={}, + tok=tok, + ) + + d = self.handler.on_exchange_third_party_invite_request( + room_id=room_id, + event_dict={ + "type": EventTypes.Member, + "room_id": room_id, + "sender": user_id, + "state_key": "@someone:example.org", + "content": { + "membership": "invite", + "third_party_invite": { + "display_name": "alice", + "signed": { + "mxid": "@alice:localhost", + "token": invite_token, + "signatures": { + "magic.forest": { + "ed25519:3": "fQpGIW1Snz+pwLZu6sTy2aHy/DYWWTspTJRPyNp0PKkymfIsNffysMl6ObMMFdIJhk6g6pwlIqZ54rxo8SLmAg" + } + } + } + } + } + } + ) + + failure = self.get_failure(d, AuthError).value + + self.assertEqual(failure.code, 403, failure) + self.assertEqual(failure.errcode, Codes.FORBIDDEN, failure) + self.assertEqual(failure.msg, "You are not invited to this room.") From ebcb6a30d7b1bdb859a1fd22d567b163a1488763 Mon Sep 17 00:00:00 2001 From: Brendan Abolivier Date: Thu, 3 Oct 2019 11:29:07 +0100 Subject: [PATCH 5/9] Lint --- tests/handlers/test_federation.py | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/tests/handlers/test_federation.py b/tests/handlers/test_federation.py index 20416a014..a18dfc0e9 100644 --- a/tests/handlers/test_federation.py +++ b/tests/handlers/test_federation.py @@ -69,11 +69,11 @@ class FederationTestCase(unittest.HomeserverTestCase): "magic.forest": { "ed25519:3": "fQpGIW1Snz+pwLZu6sTy2aHy/DYWWTspTJRPyNp0PKkymfIsNffysMl6ObMMFdIJhk6g6pwlIqZ54rxo8SLmAg" } - } - } - } - } - } + }, + }, + }, + }, + }, ) failure = self.get_failure(d, AuthError).value From 8a5e8e829b98687ea274fae47db3aa801b6f97d3 Mon Sep 17 00:00:00 2001 From: Brendan Abolivier Date: Thu, 3 Oct 2019 11:30:43 +0100 Subject: [PATCH 6/9] Lint (again) --- tests/handlers/test_federation.py | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/tests/handlers/test_federation.py b/tests/handlers/test_federation.py index a18dfc0e9..d56220f40 100644 --- a/tests/handlers/test_federation.py +++ b/tests/handlers/test_federation.py @@ -37,9 +37,7 @@ class FederationTestCase(unittest.HomeserverTestCase): user_id = self.register_user("kermit", "test") tok = self.login("kermit", "test") - room_id = self.helper.create_room_as( - room_creator=user_id, tok=tok - ) + room_id = self.helper.create_room_as(room_creator=user_id, tok=tok) # Send a 3PID invite event with an empty body so it's considered as a revoked one. invite_token = "sometoken" From 81d51ce48b449ee55bdcc17b76050283d848d405 Mon Sep 17 00:00:00 2001 From: Brendan Abolivier Date: Fri, 4 Oct 2019 11:16:19 +0100 Subject: [PATCH 7/9] Incorporate review --- synapse/handlers/federation.py | 22 ++++++++-------------- 1 file changed, 8 insertions(+), 14 deletions(-) diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py index 91f3a6929..58a165488 100644 --- a/synapse/handlers/federation.py +++ b/synapse/handlers/federation.py @@ -2600,20 +2600,14 @@ class FederationHandler(BaseHandler): ) if original_invite: # If the m.room.third_party_invite event's content is empty, it means the - # invite has been revoked. - if original_invite.content: - display_name = original_invite.content["display_name"] - event_dict["content"]["third_party_invite"][ - "display_name" - ] = display_name - else: - # Don't discard or raise an error here because that's not the right place - # to do auth checks. The auth check will fail on this invite because we - # won't be able to fetch public keys from the m.room.third_party_invite - # event's content (because it's empty). - logger.info( - "Found invite event for third_party_invite but it has been revoked" - ) + # invite has been revoked. In this case, we don't have to raise an error here + # because the auth check will fail on the invite (because it's not able to + # fetch public keys from the m.room.third_party_invite event's content, which + # is empty. + display_name = original_invite.content.get("display_name") + event_dict["content"]["third_party_invite"][ + "display_name" + ] = display_name else: logger.info( "Could not find invite event for third_party_invite: %r", event_dict From 4676732ca061ede3089b9c9b97a6d6b523b8c8e0 Mon Sep 17 00:00:00 2001 From: Brendan Abolivier Date: Fri, 4 Oct 2019 11:18:28 +0100 Subject: [PATCH 8/9] Lint --- synapse/handlers/federation.py | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py index 58a165488..b2b3a7e22 100644 --- a/synapse/handlers/federation.py +++ b/synapse/handlers/federation.py @@ -2605,9 +2605,7 @@ class FederationHandler(BaseHandler): # fetch public keys from the m.room.third_party_invite event's content, which # is empty. display_name = original_invite.content.get("display_name") - event_dict["content"]["third_party_invite"][ - "display_name" - ] = display_name + event_dict["content"]["third_party_invite"]["display_name"] = display_name else: logger.info( "Could not find invite event for third_party_invite: %r", event_dict From 21d51ab59852d6a4d504a6ccd79ad82070c03a12 Mon Sep 17 00:00:00 2001 From: Brendan Abolivier Date: Fri, 4 Oct 2019 11:21:24 +0100 Subject: [PATCH 9/9] Typo --- synapse/handlers/federation.py | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py index b2b3a7e22..50fc0fde2 100644 --- a/synapse/handlers/federation.py +++ b/synapse/handlers/federation.py @@ -2603,7 +2603,7 @@ class FederationHandler(BaseHandler): # invite has been revoked. In this case, we don't have to raise an error here # because the auth check will fail on the invite (because it's not able to # fetch public keys from the m.room.third_party_invite event's content, which - # is empty. + # is empty). display_name = original_invite.content.get("display_name") event_dict["content"]["third_party_invite"]["display_name"] = display_name else: