diff options
| -rw-r--r-- | changelog.d/8708.misc | 1 | ||||
| -rw-r--r-- | mypy.ini | 1 | ||||
| -rw-r--r-- | synapse/events/validator.py | 27 | ||||
| -rw-r--r-- | synapse/handlers/message.py | 3 | ||||
| -rw-r--r-- | tests/handlers/test_message.py | 57 |
5 files changed, 80 insertions, 9 deletions
diff --git a/changelog.d/8708.misc b/changelog.d/8708.misc new file mode 100644 index 0000000000..be679fb0f8 --- /dev/null +++ b/changelog.d/8708.misc @@ -0,0 +1 @@ +Block attempts by clients to send server ACLs, or redactions of server ACLs, that would result in the local server being blocked from the room. diff --git a/mypy.ini b/mypy.ini index 1ece2ba082..fc9f8d8050 100644 --- a/mypy.ini +++ b/mypy.ini @@ -13,6 +13,7 @@ files = synapse/config, synapse/event_auth.py, synapse/events/builder.py, + synapse/events/validator.py, synapse/events/spamcheck.py, synapse/federation, synapse/handlers/_base.py, diff --git a/synapse/events/validator.py b/synapse/events/validator.py index 5f9af8529b..f8f3b1a31e 100644 --- a/synapse/events/validator.py +++ b/synapse/events/validator.py @@ -13,20 +13,26 @@ # See the License for the specific language governing permissions and # limitations under the License. +from typing import Union + from synapse.api.constants import MAX_ALIAS_LENGTH, EventTypes, Membership from synapse.api.errors import Codes, SynapseError from synapse.api.room_versions import EventFormatVersions +from synapse.config.homeserver import HomeServerConfig +from synapse.events import EventBase +from synapse.events.builder import EventBuilder from synapse.events.utils import validate_canonicaljson +from synapse.federation.federation_server import server_matches_acl_event from synapse.types import EventID, RoomID, UserID class EventValidator: - def validate_new(self, event, config): + def validate_new(self, event: EventBase, config: HomeServerConfig): """Validates the event has roughly the right format Args: - event (FrozenEvent): The event to validate. - config (Config): The homeserver's configuration. + event: The event to validate. + config: The homeserver's configuration. """ self.validate_builder(event) @@ -76,12 +82,18 @@ class EventValidator: if event.type == EventTypes.Retention: self._validate_retention(event) - def _validate_retention(self, event): + if event.type == EventTypes.ServerACL: + if not server_matches_acl_event(config.server_name, event): + raise SynapseError( + 400, "Can't create an ACL event that denies the local server" + ) + + def _validate_retention(self, event: EventBase): """Checks that an event that defines the retention policy for a room respects the format enforced by the spec. Args: - event (FrozenEvent): The event to validate. + event: The event to validate. """ if not event.is_state(): raise SynapseError(code=400, msg="must be a state event") @@ -116,13 +128,10 @@ class EventValidator: errcode=Codes.BAD_JSON, ) - def validate_builder(self, event): + def validate_builder(self, event: Union[EventBase, EventBuilder]): """Validates that the builder/event has roughly the right format. Only checks values that we expect a proto event to have, rather than all the fields an event would have - - Args: - event (EventBuilder|FrozenEvent) """ strings = ["room_id", "sender", "type"] diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py index ca5602c13e..c6791fb912 100644 --- a/synapse/handlers/message.py +++ b/synapse/handlers/message.py @@ -1138,6 +1138,9 @@ class EventCreationHandler: if original_event.room_id != event.room_id: raise SynapseError(400, "Cannot redact event from a different room") + if original_event.type == EventTypes.ServerACL: + raise AuthError(403, "Redacting server ACL events is not permitted") + prev_state_ids = await context.get_prev_state_ids() auth_events_ids = self.auth.compute_auth_events( event, prev_state_ids, for_verification=True diff --git a/tests/handlers/test_message.py b/tests/handlers/test_message.py index 2e0fea04af..8b57081cbe 100644 --- a/tests/handlers/test_message.py +++ b/tests/handlers/test_message.py @@ -154,3 +154,60 @@ class EventCreationTestCase(unittest.HomeserverTestCase): # Check that we've deduplicated the events. self.assertEqual(len(events), 2) self.assertEqual(events[0].event_id, events[1].event_id) + + +class ServerAclValidationTestCase(unittest.HomeserverTestCase): + servlets = [ + admin.register_servlets, + login.register_servlets, + room.register_servlets, + ] + + def prepare(self, reactor, clock, hs): + self.user_id = self.register_user("tester", "foobar") + self.access_token = self.login("tester", "foobar") + self.room_id = self.helper.create_room_as(self.user_id, tok=self.access_token) + + def test_allow_server_acl(self): + """Test that sending an ACL that blocks everyone but ourselves works. + """ + + self.helper.send_state( + self.room_id, + EventTypes.ServerACL, + body={"allow": [self.hs.hostname]}, + tok=self.access_token, + expect_code=200, + ) + + def test_deny_server_acl_block_outselves(self): + """Test that sending an ACL that blocks ourselves does not work. + """ + self.helper.send_state( + self.room_id, + EventTypes.ServerACL, + body={}, + tok=self.access_token, + expect_code=400, + ) + + def test_deny_redact_server_acl(self): + """Test that attempting to redact an ACL is blocked. + """ + + body = self.helper.send_state( + self.room_id, + EventTypes.ServerACL, + body={"allow": [self.hs.hostname]}, + tok=self.access_token, + expect_code=200, + ) + event_id = body["event_id"] + + # Redaction of event should fail. + path = "/_matrix/client/r0/rooms/%s/redact/%s" % (self.room_id, event_id) + request, channel = self.make_request( + "POST", path, content={}, access_token=self.access_token + ) + self.render(request) + self.assertEqual(int(channel.result["code"]), 403) |