Files
synapse/tests/federation/test_federation_devices.py
T
Paul Chobert 84ac9ffe37 Drop federation device list updates from non-compliant user IDs (#20115)
This partially fixes the bug
https://github.com/element-hq/synapse/issues/20116

Device list update EDUs from non-compliant (grandfathered historical)
user IDs are currently accepted over federation, stored, and surfaced to
clients in `/sync`'s `device_lists.changed` array.

> For current room versions, servers must still accept events using such
user IDs over federation; however they SHOULD NOT forward such user IDs
to clients when referenced outside the context of an event. For example,
device list updates from non-compliant user IDs would be dropped by the
receiving server.
>
> -- [Matrix
spec](https://spec.matrix.org/v1.14/appendices/#historical-user-ids),
clarified in Matrix v1.14 by
[matrix-spec#1506](https://github.com/matrix-org/matrix-spec/issues/1506)


### Problem Example

A remote server sends an `m.device_list_update` EDU for
`@héllo:remote.example` (non-ASCII localpart, outside the compliant
U+0021–U+007E range). Synapse:
- accepts and processes the update (resyncing the user's device list if
needed)
- stores it in the remote device list cache
- forwards `@héllo:remote.example` to local clients via
`device_lists.changed` in `/sync` (**the leak** — a non-compliant user
ID referenced outside event context)

---

### Pull Request Checklist

<!-- Please read
https://element-hq.github.io/synapse/latest/development/contributing_guide.html
before submitting your pull request -->

* [x] Pull request is based on the develop branch
* [x] Pull request includes a [changelog
file](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#changelog).
The entry should:
- Be a short description of your change which makes sense to users.
"Fixed a bug that prevented receiving messages from other servers."
instead of "Moved X method from `EventStore` to `EventWorkerStore`.".
  - Use markdown where necessary, mostly for `code blocks`.
  - End with either a period (.) or an exclamation mark (!).
  - Start with a capital letter.
- Feel free to credit yourself, by adding a sentence "Contributed by
@github_username." or "Contributed by [Your Name]." to the end of the
entry.
* [x] [Code
style](https://element-hq.github.io/synapse/latest/code_style.html) is
correct (run the
[linters](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#run-the-linters))
2026-09-16 11:08:36 +02:00

217 lines
8.6 KiB
Python

#
# This file is licensed under the Affero General Public License (AGPL) version 3.
#
# Copyright (C) 2024 New Vector, Ltd
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# See the GNU Affero General Public License for more details:
# <https://www.gnu.org/licenses/agpl-3.0.html>.
#
# Originally licensed under the Apache License, Version 2.0:
# <http://www.apache.org/licenses/LICENSE-2.0>.
#
# [This file includes modifications made by New Vector Limited]
#
#
import logging
from unittest.mock import AsyncMock, Mock
from twisted.internet.testing import MemoryReactor
from synapse.handlers.device import DeviceListUpdater
from synapse.server import HomeServer
from synapse.types import JsonDict
from synapse.util.clock import Clock
from synapse.util.retryutils import NotRetryingDestination
from tests import unittest
logger = logging.getLogger(__name__)
class DeviceListResyncTestCase(unittest.HomeserverTestCase):
def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
self.store = self.hs.get_datastores().main
def test_retry_device_list_resync(self) -> None:
"""Tests that device lists are marked as stale if they couldn't be synced, and
that stale device lists are retried periodically.
"""
remote_user_id = "@john:test_remote"
remote_origin = "test_remote"
# Track the number of attempts to resync the user's device list.
self.resync_attempts = 0
# When this function is called, increment the number of resync attempts (only if
# we're querying devices for the right user ID), then raise a
# NotRetryingDestination error to fail the resync gracefully.
def query_user_devices(
destination: str, user_id: str, timeout: int = 30000
) -> JsonDict:
if user_id == remote_user_id:
self.resync_attempts += 1
raise NotRetryingDestination(0, 0, destination)
# Register the mock on the federation client.
federation_client = self.hs.get_federation_client()
federation_client.query_user_devices = Mock(side_effect=query_user_devices) # type: ignore[method-assign]
# Register a mock on the store so that the incoming update doesn't fail because
# we don't share a room with the user.
self.store.get_rooms_for_user = AsyncMock(return_value=["!someroom:test"])
# Manually inject a fake device list update. We need this update to include at
# least one prev_id so that the user's device list will need to be retried.
device_list_updater = self.hs.get_device_handler().device_list_updater
assert isinstance(device_list_updater, DeviceListUpdater)
self.get_success(
device_list_updater.incoming_device_list_update(
origin=remote_origin,
edu_content={
"deleted": False,
"device_display_name": "Mobile",
"device_id": "QBUAZIFURK",
"prev_id": [5],
"stream_id": 6,
"user_id": remote_user_id,
},
)
)
# Check that there was one resync attempt.
self.assertEqual(self.resync_attempts, 1)
# Check that the resync attempt failed and caused the user's device list to be
# marked as stale.
need_resync = self.get_success(
self.store.get_user_ids_requiring_device_list_resync()
)
self.assertIn(remote_user_id, need_resync)
# Check that waiting for 30 seconds caused Synapse to retry resyncing the device
# list.
self.reactor.advance(30)
self.assertEqual(self.resync_attempts, 2)
def test_non_compliant_user_id_update_dropped(self) -> None:
"""Tests that device list updates from non-compliant (grandfathered
historical) user IDs are dropped, per
https://spec.matrix.org/v1.14/appendices/#historical-user-ids
"""
remote_user_id = "@héllo:test_remote"
remote_origin = "test_remote"
# Track the number of attempts to resync the user's device list.
self.resync_attempts = 0
# When this function is called, increment the number of resync attempts (only if
# we're querying devices for the right user ID), then raise a
# NotRetryingDestination error to fail the resync gracefully.
def query_user_devices(
destination: str, user_id: str, timeout: int = 30000
) -> JsonDict:
if user_id == remote_user_id:
self.resync_attempts += 1
raise NotRetryingDestination(0, 0, destination)
# Register the mock on the federation client.
federation_client = self.hs.get_federation_client()
federation_client.query_user_devices = Mock(side_effect=query_user_devices) # type: ignore[method-assign]
# Share room with user.
self.store.get_rooms_for_user = AsyncMock(return_value=["!someroom:test"])
# Manually inject a fake device list update from the non-compliant user ID.
device_list_updater = self.hs.get_device_handler().device_list_updater
assert isinstance(device_list_updater, DeviceListUpdater)
self.get_success(
device_list_updater.incoming_device_list_update(
origin=remote_origin,
edu_content={
"deleted": False,
"device_display_name": "Mobile",
"device_id": "QBUAZIFURK",
"prev_id": [5],
"stream_id": 6,
"user_id": remote_user_id,
},
)
)
# The update should have been dropped without triggering a resync.
self.assertEqual(self.resync_attempts, 0)
# The user should not have been marked as needing a device list resync.
need_resync = self.get_success(
self.store.get_user_ids_requiring_device_list_resync()
)
self.assertNotIn(remote_user_id, need_resync)
def test_cross_signing_keys_retry(self) -> None:
"""Tests that resyncing a device list correctly processes cross-signing keys from
the remote server.
"""
remote_user_id = "@john:test_remote"
remote_master_key = "85T7JXPFBAySB/jwby4S3lBPTqY3+Zg53nYuGmu1ggY"
remote_self_signing_key = "QeIiFEjluPBtI7WQdG365QKZcFs9kqmHir6RBD0//nQ"
# Register mock device list retrieval on the federation client.
federation_client = self.hs.get_federation_client()
federation_client.query_user_devices = AsyncMock( # type: ignore[method-assign]
return_value={
"user_id": remote_user_id,
"stream_id": 1,
"devices": [],
"master_key": {
"user_id": remote_user_id,
"usage": ["master"],
"keys": {"ed25519:" + remote_master_key: remote_master_key},
},
"self_signing_key": {
"user_id": remote_user_id,
"usage": ["self_signing"],
"keys": {
"ed25519:" + remote_self_signing_key: remote_self_signing_key
},
},
}
)
# Resync the device list.
device_handler = self.hs.get_device_handler()
self.get_success(
device_handler.device_list_updater.multi_user_device_resync(
[remote_user_id]
),
)
# Retrieve the cross-signing keys for this user.
keys = self.get_success(
self.store.get_e2e_cross_signing_keys_bulk(user_ids=[remote_user_id]),
)
self.assertIn(remote_user_id, keys)
key = keys[remote_user_id]
assert key is not None
# Check that the master key is the one returned by the mock.
master_key = key["master"]
self.assertEqual(len(master_key["keys"]), 1)
self.assertTrue("ed25519:" + remote_master_key in master_key["keys"].keys())
self.assertTrue(remote_master_key in master_key["keys"].values())
# Check that the self-signing key is the one returned by the mock.
self_signing_key = key["self_signing"]
self.assertEqual(len(self_signing_key["keys"]), 1)
self.assertTrue(
"ed25519:" + remote_self_signing_key in self_signing_key["keys"].keys(),
)
self.assertTrue(remote_self_signing_key in self_signing_key["keys"].values())