From d1bf5f7c9d669fcf60aadc2c6527447adef2c43c Mon Sep 17 00:00:00 2001 From: Patrick Cloke Date: Thu, 30 Sep 2021 11:13:59 -0400 Subject: Strip "join_authorised_via_users_server" from join events which do not need it. (#10933) This fixes a "Event not signed by authorising server" error when transition room member from join -> join, e.g. when updating a display name or avatar URL for restricted rooms. --- changelog.d/10933.bugfix | 1 + synapse/api/constants.py | 3 +++ synapse/event_auth.py | 12 +++++++----- synapse/events/utils.py | 2 +- synapse/federation/federation_base.py | 6 +++--- synapse/federation/federation_client.py | 6 +++--- synapse/federation/federation_server.py | 6 +++--- synapse/handlers/federation.py | 9 +++++++-- synapse/handlers/room_member.py | 10 +++++++++- tests/events/test_utils.py | 7 ++++--- tests/test_event_auth.py | 9 +++++---- 11 files changed, 46 insertions(+), 25 deletions(-) create mode 100644 changelog.d/10933.bugfix diff --git a/changelog.d/10933.bugfix b/changelog.d/10933.bugfix new file mode 100644 index 0000000000..e0694fea22 --- /dev/null +++ b/changelog.d/10933.bugfix @@ -0,0 +1 @@ +Fix a bug introduced in Synapse v1.40.0 where changing a user's display name or avatar in a restricted room would cause an authentication error. diff --git a/synapse/api/constants.py b/synapse/api/constants.py index 39fd9954d5..a31f037748 100644 --- a/synapse/api/constants.py +++ b/synapse/api/constants.py @@ -217,6 +217,9 @@ class EventContentFields: # For "marker" events MSC2716_MARKER_INSERTION = "org.matrix.msc2716.marker.insertion" + # The authorising user for joining a restricted room. + AUTHORISING_USER = "join_authorised_via_users_server" + class RoomTypes: """Understood values of the room_type field of m.room.create events.""" diff --git a/synapse/event_auth.py b/synapse/event_auth.py index eef354de6e..7a1adc2750 100644 --- a/synapse/event_auth.py +++ b/synapse/event_auth.py @@ -102,11 +102,11 @@ def validate_event_for_room_version( room_version_obj.msc3083_join_rules and event.type == EventTypes.Member and event.membership == Membership.JOIN - and "join_authorised_via_users_server" in event.content + and EventContentFields.AUTHORISING_USER in event.content ) if is_invite_via_allow_rule: authoriser_domain = get_domain_from_id( - event.content["join_authorised_via_users_server"] + event.content[EventContentFields.AUTHORISING_USER] ) if not event.signatures.get(authoriser_domain): raise AuthError(403, "Event not signed by authorising server") @@ -413,7 +413,9 @@ def _is_membership_change_allowed( # Note that if the caller is in the room or invited, then they do # not need to meet the allow rules. if not caller_in_room and not caller_invited: - authorising_user = event.content.get("join_authorised_via_users_server") + authorising_user = event.content.get( + EventContentFields.AUTHORISING_USER + ) if authorising_user is None: raise AuthError(403, "Join event is missing authorising user.") @@ -868,10 +870,10 @@ def auth_types_for_event( auth_types.add(key) if room_version.msc3083_join_rules and membership == Membership.JOIN: - if "join_authorised_via_users_server" in event.content: + if EventContentFields.AUTHORISING_USER in event.content: key = ( EventTypes.Member, - event.content["join_authorised_via_users_server"], + event.content[EventContentFields.AUTHORISING_USER], ) auth_types.add(key) diff --git a/synapse/events/utils.py b/synapse/events/utils.py index a13fb0148f..520edbbf61 100644 --- a/synapse/events/utils.py +++ b/synapse/events/utils.py @@ -105,7 +105,7 @@ def prune_event_dict(room_version: RoomVersion, event_dict: dict) -> dict: if event_type == EventTypes.Member: add_fields("membership") if room_version.msc3375_redaction_rules: - add_fields("join_authorised_via_users_server") + add_fields(EventContentFields.AUTHORISING_USER) elif event_type == EventTypes.Create: # MSC2176 rules state that create events cannot be redacted. if room_version.msc2176_redaction_rules: diff --git a/synapse/federation/federation_base.py b/synapse/federation/federation_base.py index 024e440ff4..0cd424e12a 100644 --- a/synapse/federation/federation_base.py +++ b/synapse/federation/federation_base.py @@ -15,7 +15,7 @@ import logging from collections import namedtuple -from synapse.api.constants import MAX_DEPTH, EventTypes, Membership +from synapse.api.constants import MAX_DEPTH, EventContentFields, EventTypes, Membership from synapse.api.errors import Codes, SynapseError from synapse.api.room_versions import EventFormatVersions, RoomVersion from synapse.crypto.event_signing import check_event_content_hash @@ -184,10 +184,10 @@ async def _check_sigs_on_pdu( room_version.msc3083_join_rules and pdu.type == EventTypes.Member and pdu.membership == Membership.JOIN - and "join_authorised_via_users_server" in pdu.content + and EventContentFields.AUTHORISING_USER in pdu.content ): authorising_server = get_domain_from_id( - pdu.content["join_authorised_via_users_server"] + pdu.content[EventContentFields.AUTHORISING_USER] ) try: await keyring.verify_event_for_server( diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py index 584836c04a..2ab4dec88f 100644 --- a/synapse/federation/federation_client.py +++ b/synapse/federation/federation_client.py @@ -37,7 +37,7 @@ from typing import ( import attr from prometheus_client import Counter -from synapse.api.constants import EventTypes, Membership +from synapse.api.constants import EventContentFields, EventTypes, Membership from synapse.api.errors import ( CodeMessageException, Codes, @@ -875,9 +875,9 @@ class FederationClient(FederationBase): # If the join is being authorised via allow rules, we need to send # the /send_join back to the same server that was originally used # with /make_join. - if "join_authorised_via_users_server" in pdu.content: + if EventContentFields.AUTHORISING_USER in pdu.content: destinations = [ - get_domain_from_id(pdu.content["join_authorised_via_users_server"]) + get_domain_from_id(pdu.content[EventContentFields.AUTHORISING_USER]) ] return await self._try_destination_list( diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py index 83f11d6b88..d8c0b86f23 100644 --- a/synapse/federation/federation_server.py +++ b/synapse/federation/federation_server.py @@ -34,7 +34,7 @@ from twisted.internet import defer from twisted.internet.abstract import isIPAddress from twisted.python import failure -from synapse.api.constants import EduTypes, EventTypes, Membership +from synapse.api.constants import EduTypes, EventContentFields, EventTypes, Membership from synapse.api.errors import ( AuthError, Codes, @@ -765,11 +765,11 @@ class FederationServer(FederationBase): if ( room_version.msc3083_join_rules and event.membership == Membership.JOIN - and "join_authorised_via_users_server" in event.content + and EventContentFields.AUTHORISING_USER in event.content ): # We can only authorise our own users. authorising_server = get_domain_from_id( - event.content["join_authorised_via_users_server"] + event.content[EventContentFields.AUTHORISING_USER] ) if authorising_server != self.server_name: raise SynapseError( diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py index 0a10a5c28a..043ca4a224 100644 --- a/synapse/handlers/federation.py +++ b/synapse/handlers/federation.py @@ -27,7 +27,12 @@ from unpaddedbase64 import decode_base64 from twisted.internet import defer from synapse import event_auth -from synapse.api.constants import EventTypes, Membership, RejectedReason +from synapse.api.constants import ( + EventContentFields, + EventTypes, + Membership, + RejectedReason, +) from synapse.api.errors import ( AuthError, CodeMessageException, @@ -716,7 +721,7 @@ class FederationHandler(BaseHandler): if include_auth_user_id: event_content[ - "join_authorised_via_users_server" + EventContentFields.AUTHORISING_USER ] = await self._event_auth_handler.get_user_which_could_invite( room_id, state_ids, diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py index 02103f6c9a..29b3e41cc9 100644 --- a/synapse/handlers/room_member.py +++ b/synapse/handlers/room_member.py @@ -573,6 +573,14 @@ class RoomMemberHandler(metaclass=abc.ABCMeta): errcode=Codes.BAD_JSON, ) + # The event content should *not* include the authorising user as + # it won't be properly signed. Strip it out since it might come + # back from a client updating a display name / avatar. + # + # This only applies to restricted rooms, but there should be no reason + # for a client to include it. Unconditionally remove it. + content.pop(EventContentFields.AUTHORISING_USER, None) + effective_membership_state = action if action in ["kick", "unban"]: effective_membership_state = "leave" @@ -939,7 +947,7 @@ class RoomMemberHandler(metaclass=abc.ABCMeta): # be included in the event content in order to efficiently validate # the event. content[ - "join_authorised_via_users_server" + EventContentFields.AUTHORISING_USER ] = await self.event_auth_handler.get_user_which_could_invite( room_id, current_state_ids, diff --git a/tests/events/test_utils.py b/tests/events/test_utils.py index 5446fda5e7..1dea09e480 100644 --- a/tests/events/test_utils.py +++ b/tests/events/test_utils.py @@ -12,6 +12,7 @@ # See the License for the specific language governing permissions and # limitations under the License. +from synapse.api.constants import EventContentFields from synapse.api.room_versions import RoomVersions from synapse.events import make_event_from_dict from synapse.events.utils import ( @@ -352,7 +353,7 @@ class PruneEventTestCase(unittest.TestCase): "event_id": "$test:domain", "content": { "membership": "join", - "join_authorised_via_users_server": "@user:domain", + EventContentFields.AUTHORISING_USER: "@user:domain", "other_key": "stripped", }, }, @@ -372,7 +373,7 @@ class PruneEventTestCase(unittest.TestCase): "type": "m.room.member", "content": { "membership": "join", - "join_authorised_via_users_server": "@user:domain", + EventContentFields.AUTHORISING_USER: "@user:domain", "other_key": "stripped", }, }, @@ -380,7 +381,7 @@ class PruneEventTestCase(unittest.TestCase): "type": "m.room.member", "content": { "membership": "join", - "join_authorised_via_users_server": "@user:domain", + EventContentFields.AUTHORISING_USER: "@user:domain", }, "signatures": {}, "unsigned": {}, diff --git a/tests/test_event_auth.py b/tests/test_event_auth.py index e7a7d00883..cf407c51cf 100644 --- a/tests/test_event_auth.py +++ b/tests/test_event_auth.py @@ -16,6 +16,7 @@ import unittest from typing import Optional from synapse import event_auth +from synapse.api.constants import EventContentFields from synapse.api.errors import AuthError from synapse.api.room_versions import RoomVersions from synapse.events import EventBase, make_event_from_dict @@ -353,7 +354,7 @@ class EventAuthTestCase(unittest.TestCase): authorised_join_event = _join_event( pleb, additional_content={ - "join_authorised_via_users_server": "@creator:example.com" + EventContentFields.AUTHORISING_USER: "@creator:example.com" }, ) event_auth.check_auth_rules_for_event( @@ -376,7 +377,7 @@ class EventAuthTestCase(unittest.TestCase): _join_event( pleb, additional_content={ - "join_authorised_via_users_server": "@inviter:foo.test" + EventContentFields.AUTHORISING_USER: "@inviter:foo.test" }, ), pl_auth_events, @@ -401,7 +402,7 @@ class EventAuthTestCase(unittest.TestCase): _join_event( pleb, additional_content={ - "join_authorised_via_users_server": "@other:example.com" + EventContentFields.AUTHORISING_USER: "@other:example.com" }, ), auth_events, @@ -417,7 +418,7 @@ class EventAuthTestCase(unittest.TestCase): "join", sender=creator, additional_content={ - "join_authorised_via_users_server": "@inviter:foo.test" + EventContentFields.AUTHORISING_USER: "@inviter:foo.test" }, ), auth_events, -- cgit 1.4.1