From a5c26750b50563f2edda8b5d37c70b1d49e5f34c Mon Sep 17 00:00:00 2001
From: Sean Quah <8349537+squahtx@users.noreply.github.com>
Date: Mon, 16 May 2022 14:06:04 +0100
Subject: [PATCH] Fix room upgrades creating an empty room when auth fails
(#12696)
Signed-off-by: Sean Quah <seanq@element.io>
---
changelog.d/12696.bugfix | 1 +
synapse/handlers/room.py | 137 +++++++++++-------
.../test_sharded_event_persister.py | 14 +-
3 files changed, 90 insertions(+), 62 deletions(-)
create mode 100644 changelog.d/12696.bugfix
diff --git a/changelog.d/12696.bugfix b/changelog.d/12696.bugfix
new file mode 100644
index 0000000000..e410184a22
--- /dev/null
+++ b/changelog.d/12696.bugfix
@@ -0,0 +1 @@
+Fix a long-standing bug where an empty room would be created when a user with an insufficient power level tried to upgrade a room.
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index e71c78adad..23baa50d03 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -33,6 +33,7 @@ from typing import (
import attr
from typing_extensions import TypedDict
+import synapse.events.snapshot
from synapse.api.constants import (
EventContentFields,
EventTypes,
@@ -77,7 +78,6 @@ from synapse.types import (
create_requester,
)
from synapse.util import stringutils
-from synapse.util.async_helpers import Linearizer
from synapse.util.caches.response_cache import ResponseCache
from synapse.util.stringutils import parse_and_validate_server_name
from synapse.visibility import filter_events_for_client
@@ -155,9 +155,6 @@ class RoomCreationHandler:
self._replication = hs.get_replication_data_handler()
- # linearizer to stop two upgrades happening at once
- self._upgrade_linearizer = Linearizer("room_upgrade_linearizer")
-
# If a user tries to update the same room multiple times in quick
# succession, only process the first attempt and return its result to
# subsequent requests
@@ -200,50 +197,17 @@ class RoomCreationHandler:
400, "An upgrade for this room is currently in progress"
)
- # Upgrade the room
- #
- # If this user has sent multiple upgrade requests for the same room
- # and one of them is not complete yet, cache the response and
- # return it to all subsequent requests
- ret = await self._upgrade_response_cache.wrap(
- (old_room_id, user_id),
- self._upgrade_room,
- requester,
- old_room_id,
- new_version, # args for _upgrade_room
- )
-
- return ret
-
- async def _upgrade_room(
- self, requester: Requester, old_room_id: str, new_version: RoomVersion
- ) -> str:
- """
- Args:
- requester: the user requesting the upgrade
- old_room_id: the id of the room to be replaced
- new_versions: the version to upgrade the room to
-
- Raises:
- ShadowBanError if the requester is shadow-banned.
- """
- user_id = requester.user.to_string()
- assert self.hs.is_mine_id(user_id), "User must be our own: %s" % (user_id,)
-
- # start by allocating a new room id
- r = await self.store.get_room(old_room_id)
- if r is None:
+ # Check whether the room exists and 404 if it doesn't.
+ # We could go straight for the auth check, but that will raise a 403 instead.
+ old_room = await self.store.get_room(old_room_id)
+ if old_room is None:
raise NotFoundError("Unknown room id %s" % (old_room_id,))
- new_room_id = await self._generate_room_id(
- creator_id=user_id,
- is_public=r["is_public"],
- room_version=new_version,
- )
- logger.info("Creating new room %s to replace %s", new_room_id, old_room_id)
+ new_room_id = self._generate_room_id()
- # we create and auth the tombstone event before properly creating the new
- # room, to check our user has perms in the old room.
+ # Check whether the user has the power level to carry out the upgrade.
+ # `check_auth_rules_from_context` will check that they are in the room and have
+ # the required power level to send the tombstone event.
(
tombstone_event,
tombstone_context,
@@ -266,6 +230,63 @@ class RoomCreationHandler:
old_room_version, tombstone_event, tombstone_context
)
+ # Upgrade the room
+ #
+ # If this user has sent multiple upgrade requests for the same room
+ # and one of them is not complete yet, cache the response and
+ # return it to all subsequent requests
+ ret = await self._upgrade_response_cache.wrap(
+ (old_room_id, user_id),
+ self._upgrade_room,
+ requester,
+ old_room_id,
+ old_room, # args for _upgrade_room
+ new_room_id,
+ new_version,
+ tombstone_event,
+ tombstone_context,
+ )
+
+ return ret
+
+ async def _upgrade_room(
+ self,
+ requester: Requester,
+ old_room_id: str,
+ old_room: Dict[str, Any],
+ new_room_id: str,
+ new_version: RoomVersion,
+ tombstone_event: EventBase,
+ tombstone_context: synapse.events.snapshot.EventContext,
+ ) -> str:
+ """
+ Args:
+ requester: the user requesting the upgrade
+ old_room_id: the id of the room to be replaced
+ old_room: a dict containing room information for the room to be replaced,
+ as returned by `RoomWorkerStore.get_room`.
+ new_room_id: the id of the replacement room
+ new_version: the version to upgrade the room to
+ tombstone_event: the tombstone event to send to the old room
+ tombstone_context: the context for the tombstone event
+
+ Raises:
+ ShadowBanError if the requester is shadow-banned.
+ """
+ user_id = requester.user.to_string()
+ assert self.hs.is_mine_id(user_id), "User must be our own: %s" % (user_id,)
+
+ logger.info("Creating new room %s to replace %s", new_room_id, old_room_id)
+
+ # create the new room. may raise a `StoreError` in the exceedingly unlikely
+ # event of a room ID collision.
+ await self.store.store_room(
+ room_id=new_room_id,
+ room_creator_user_id=user_id,
+ is_public=old_room["is_public"],
+ room_version=new_version,
+ )
+
await self.clone_existing_room(
requester,
old_room_id=old_room_id,
@@ -782,7 +803,7 @@ class RoomCreationHandler:
visibility = config.get("visibility", "private")
is_public = visibility == "public"
- room_id = await self._generate_room_id(
+ room_id = await self._generate_and_create_room_id(
creator_id=user_id,
is_public=is_public,
room_version=room_version,
@@ -1104,7 +1125,26 @@ class RoomCreationHandler:
return last_sent_stream_id
- async def _generate_room_id(
+ def _generate_room_id(self) -> str:
+ """Generates a random room ID.
+
+ Room IDs look like "!opaque_id:domain" and are case-sensitive as per the spec
+ at https://spec.matrix.org/v1.2/appendices/#room-ids-and-event-ids.
+
+ Does not check for collisions with existing rooms or prevent future calls from
+ returning the same room ID. To ensure the uniqueness of a new room ID, use
+ `_generate_and_create_room_id` instead.
+
+ Synapse's room IDs are 18 [a-zA-Z] characters long, which comes out to around
+ 102 bits.
+
+ Returns:
+ A random room ID of the form "!opaque_id:domain".
+ """
+ random_string = stringutils.random_string(18)
+ return RoomID(random_string, self.hs.hostname).to_string()
+
+ async def _generate_and_create_room_id(
self,
creator_id: str,
is_public: bool,
@@ -1115,8 +1155,7 @@ class RoomCreationHandler:
attempts = 0
while attempts < 5:
try:
- random_string = stringutils.random_string(18)
- gen_room_id = RoomID(random_string, self.hs.hostname).to_string()
+ gen_room_id = self._generate_room_id()
await self.store.store_room(
room_id=gen_room_id,
room_creator_user_id=creator_id,
diff --git a/tests/replication/test_sharded_event_persister.py b/tests/replication/test_sharded_event_persister.py
index 5f142e84c3..a7ca68069e 100644
--- a/tests/replication/test_sharded_event_persister.py
+++ b/tests/replication/test_sharded_event_persister.py
@@ -14,7 +14,6 @@
import logging
from unittest.mock import patch
-from synapse.api.room_versions import RoomVersion
from synapse.rest import admin
from synapse.rest.client import login, room, sync
from synapse.storage.util.id_generators import MultiWriterIdGenerator
@@ -64,21 +63,10 @@ class EventPersisterShardTestCase(BaseMultiWorkerStreamTestCase):
# We control the room ID generation by patching out the
# `_generate_room_id` method
- async def generate_room(
- creator_id: str, is_public: bool, room_version: RoomVersion
- ):
- await self.store.store_room(
- room_id=room_id,
- room_creator_user_id=creator_id,
- is_public=is_public,
- room_version=room_version,
- )
- return room_id
-
with patch(
"synapse.handlers.room.RoomCreationHandler._generate_room_id"
) as mock:
- mock.side_effect = generate_room
+ mock.side_effect = lambda: room_id
self.helper.create_room_as(user_id, tok=tok)
def test_basic(self):