diff --git a/changelog.d/5440.feature b/changelog.d/5440.feature new file mode 100644 index 0000000000..63d9b58734 --- /dev/null +++ b/changelog.d/5440.feature @@ -0,0 +1 @@ +Allow server admins to define implementations of extra rules for allowing or denying incoming events. diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml index 4d7e6f3eb5..bd80d97a93 100644 --- a/docs/sample_config.yaml +++ b/docs/sample_config.yaml @@ -1351,3 +1351,16 @@ password_config: # alias: "*" # room_id: "*" # action: allow + + +# Server admins can define a Python module that implements extra rules for +# allowing or denying incoming events. In order to work, this module needs to +# override the methods defined in synapse/events/third_party_rules.py. +# +# This feature is designed to be used in closed federations only, where each +# participating server enforces the same rules. +# +#third_party_event_rules: +# module: "my_custom_project.SuperRulesSet" +# config: +# example_option: 'things' diff --git a/synapse/config/homeserver.py b/synapse/config/homeserver.py index 5c4fc8ff21..acadef4fd3 100644 --- a/synapse/config/homeserver.py +++ b/synapse/config/homeserver.py @@ -38,6 +38,7 @@ from .server import ServerConfig from .server_notices_config import ServerNoticesConfig from .spam_checker import SpamCheckerConfig from .stats import StatsConfig +from .third_party_event_rules import ThirdPartyRulesConfig from .tls import TlsConfig from .user_directory import UserDirectoryConfig from .voip import VoipConfig @@ -73,5 +74,6 @@ class HomeServerConfig( StatsConfig, ServerNoticesConfig, RoomDirectoryConfig, + ThirdPartyRulesConfig, ): pass diff --git a/synapse/config/third_party_event_rules.py b/synapse/config/third_party_event_rules.py new file mode 100644 index 0000000000..a89dd5f98a --- /dev/null +++ b/synapse/config/third_party_event_rules.py @@ -0,0 +1,42 @@ +# -*- 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.util.module_loader import load_module + +from ._base import Config + + +class ThirdPartyRulesConfig(Config): + def read_config(self, config): + self.third_party_event_rules = None + + provider = config.get("third_party_event_rules", None) + if provider is not None: + self.third_party_event_rules = load_module(provider) + + def default_config(self, **kwargs): + return """\ + # Server admins can define a Python module that implements extra rules for + # allowing or denying incoming events. In order to work, this module needs to + # override the methods defined in synapse/events/third_party_rules.py. + # + # This feature is designed to be used in closed federations only, where each + # participating server enforces the same rules. + # + #third_party_event_rules: + # module: "my_custom_project.SuperRulesSet" + # config: + # example_option: 'things' + """ diff --git a/synapse/events/third_party_rules.py b/synapse/events/third_party_rules.py new file mode 100644 index 0000000000..9f98d51523 --- /dev/null +++ b/synapse/events/third_party_rules.py @@ -0,0 +1,62 @@ +# -*- 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 twisted.internet import defer + + +class ThirdPartyEventRules(object): + """Allows server admins to provide a Python module implementing an extra set of rules + to apply when processing events. + + This is designed to help admins of closed federations with enforcing custom + behaviours. + """ + + def __init__(self, hs): + self.third_party_rules = None + + self.store = hs.get_datastore() + + module = None + config = None + if hs.config.third_party_event_rules: + module, config = hs.config.third_party_event_rules + + if module is not None: + self.third_party_rules = module(config=config) + + @defer.inlineCallbacks + def check_event_allowed(self, event, context): + """Check if a provided event should be allowed in the given context. + + Args: + event (synapse.events.EventBase): The event to be checked. + context (synapse.events.snapshot.EventContext): The context of the event. + + Returns: + defer.Deferred(bool), True if the event should be allowed, False if not. + """ + if self.third_party_rules is None: + defer.returnValue(True) + + prev_state_ids = yield context.get_prev_state_ids(self.store) + + # Retrieve the state events from the database. + state_events = {} + for key, event_id in prev_state_ids.items(): + state_events[key] = yield self.store.get_event(event_id, allow_none=True) + + ret = yield self.third_party_rules.check_event_allowed(event, state_events) + defer.returnValue(ret) diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py index ac5ca79143..983ac9f915 100644 --- a/synapse/handlers/federation.py +++ b/synapse/handlers/federation.py @@ -1,6 +1,7 @@ # -*- coding: utf-8 -*- # Copyright 2014-2016 OpenMarket Ltd -# Copyright 2018 New Vector Ltd +# Copyright 2017-2018 New Vector Ltd +# 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. @@ -33,6 +34,7 @@ from synapse.api.constants import EventTypes, Membership, RejectedReason from synapse.api.errors import ( AuthError, CodeMessageException, + Codes, FederationDeniedError, FederationError, RequestSendFailed, @@ -127,6 +129,8 @@ class FederationHandler(BaseHandler): self.room_queues = {} self._room_pdu_linearizer = Linearizer("fed_room_pdu") + self.third_party_event_rules = hs.get_third_party_event_rules() + @defer.inlineCallbacks def on_receive_pdu( self, origin, pdu, sent_to_us_directly=False, @@ -1258,6 +1262,15 @@ class FederationHandler(BaseHandler): logger.warn("Failed to create join %r because %s", event, e) raise e + event_allowed = yield self.third_party_event_rules.check_event_allowed( + event, context, + ) + if not event_allowed: + logger.info("Creation of join %s forbidden by third-party rules", event) + raise SynapseError( + 403, "This event is not allowed in this context", Codes.FORBIDDEN, + ) + # The remote hasn't signed it yet, obviously. We'll do the full checks # when we get the event back in `on_send_join_request` yield self.auth.check_from_context( @@ -1300,6 +1313,15 @@ class FederationHandler(BaseHandler): origin, event ) + event_allowed = yield self.third_party_event_rules.check_event_allowed( + event, context, + ) + if not event_allowed: + logger.info("Sending of join %s forbidden by third-party rules", event) + raise SynapseError( + 403, "This event is not allowed in this context", Codes.FORBIDDEN, + ) + logger.debug( "on_send_join_request: After _handle_new_event: %s, sigs: %s", event.event_id, @@ -1458,6 +1480,15 @@ class FederationHandler(BaseHandler): builder=builder, ) + event_allowed = yield self.third_party_event_rules.check_event_allowed( + event, context, + ) + if not event_allowed: + logger.warning("Creation of leave %s forbidden by third-party rules", event) + raise SynapseError( + 403, "This event is not allowed in this context", Codes.FORBIDDEN, + ) + try: # The remote hasn't signed it yet, obviously. We'll do the full checks # when we get the event back in `on_send_leave_request` @@ -1484,10 +1515,19 @@ class FederationHandler(BaseHandler): event.internal_metadata.outlier = False - yield self._handle_new_event( + context = yield self._handle_new_event( origin, event ) + event_allowed = yield self.third_party_event_rules.check_event_allowed( + event, context, + ) + if not event_allowed: + logger.info("Sending of leave %s forbidden by third-party rules", event) + raise SynapseError( + 403, "This event is not allowed in this context", Codes.FORBIDDEN, + ) + logger.debug( "on_send_leave_request: After _handle_new_event: %s, sigs: %s", event.event_id, @@ -2550,6 +2590,18 @@ class FederationHandler(BaseHandler): builder=builder ) + event_allowed = yield self.third_party_event_rules.check_event_allowed( + event, context, + ) + if not event_allowed: + logger.info( + "Creation of threepid invite %s forbidden by third-party rules", + event, + ) + raise SynapseError( + 403, "This event is not allowed in this context", Codes.FORBIDDEN, + ) + event, context = yield self.add_display_name_to_third_party_invite( room_version, event_dict, event, context ) @@ -2598,6 +2650,18 @@ class FederationHandler(BaseHandler): builder=builder, ) + event_allowed = yield self.third_party_event_rules.check_event_allowed( + event, context, + ) + if not event_allowed: + logger.warning( + "Exchange of threepid invite %s forbidden by third-party rules", + event, + ) + raise SynapseError( + 403, "This event is not allowed in this context", Codes.FORBIDDEN, + ) + event, context = yield self.add_display_name_to_third_party_invite( room_version, event_dict, event, context ) diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py index 0b02469ceb..11650dc80c 100644 --- a/synapse/handlers/message.py +++ b/synapse/handlers/message.py @@ -1,6 +1,7 @@ # -*- coding: utf-8 -*- -# Copyright 2014 - 2016 OpenMarket Ltd -# Copyright 2017 - 2018 New Vector Ltd +# Copyright 2014-2016 OpenMarket Ltd +# Copyright 2017-2018 New Vector Ltd +# 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. @@ -248,6 +249,7 @@ class EventCreationHandler(object): self.action_generator = hs.get_action_generator() self.spam_checker = hs.get_spam_checker() + self.third_party_event_rules = hs.get_third_party_event_rules() self._block_events_without_consent_error = ( self.config.block_events_without_consent_error @@ -658,6 +660,14 @@ class EventCreationHandler(object): else: room_version = yield self.store.get_room_version(event.room_id) + event_allowed = yield self.third_party_event_rules.check_event_allowed( + event, context, + ) + if not event_allowed: + raise SynapseError( + 403, "This event is not allowed in this context", Codes.FORBIDDEN, + ) + try: yield self.auth.check_from_context(room_version, event, context) except AuthError as err: diff --git a/synapse/server.py b/synapse/server.py index 9229a68a8d..a54e023cc9 100644 --- a/synapse/server.py +++ b/synapse/server.py @@ -1,5 +1,7 @@ # -*- coding: utf-8 -*- # Copyright 2014-2016 OpenMarket Ltd +# Copyright 2017-2018 New Vector Ltd +# 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. @@ -35,6 +37,7 @@ from synapse.crypto import context_factory from synapse.crypto.keyring import Keyring from synapse.events.builder import EventBuilderFactory from synapse.events.spamcheck import SpamChecker +from synapse.events.third_party_rules import ThirdPartyEventRules from synapse.events.utils import EventClientSerializer from synapse.federation.federation_client import FederationClient from synapse.federation.federation_server import ( @@ -178,6 +181,7 @@ class HomeServer(object): 'groups_attestation_renewer', 'secrets', 'spam_checker', + 'third_party_event_rules', 'room_member_handler', 'federation_registry', 'server_notices_manager', @@ -483,6 +487,9 @@ class HomeServer(object): def build_spam_checker(self): return SpamChecker(self) + def build_third_party_event_rules(self): + return ThirdPartyEventRules(self) + def build_room_member_handler(self): if self.config.worker_app: return RoomMemberWorkerHandler(self) diff --git a/tests/rest/client/third_party_rules.py b/tests/rest/client/third_party_rules.py new file mode 100644 index 0000000000..7167fc56b6 --- /dev/null +++ b/tests/rest/client/third_party_rules.py @@ -0,0 +1,79 @@ +# -*- 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.rest import admin +from synapse.rest.client.v1 import login, room + +from tests import unittest + + +class ThirdPartyRulesTestModule(object): + def __init__(self, config): + pass + + def check_event_allowed(self, event, context): + if event.type == "foo.bar.forbidden": + return False + else: + return True + + @staticmethod + def parse_config(config): + return config + + +class ThirdPartyRulesTestCase(unittest.HomeserverTestCase): + servlets = [ + admin.register_servlets, + login.register_servlets, + room.register_servlets, + ] + + def make_homeserver(self, reactor, clock): + config = self.default_config() + config["third_party_event_rules"] = { + "module": "tests.rest.client.third_party_rules.ThirdPartyRulesTestModule", + "config": {}, + } + + self.hs = self.setup_test_homeserver(config=config) + return self.hs + + def test_third_party_rules(self): + """Tests that a forbidden event is forbidden from being sent, but an allowed one + can be sent. + """ + user_id = self.register_user("kermit", "monkey") + tok = self.login("kermit", "monkey") + + room_id = self.helper.create_room_as(user_id, tok=tok) + + request, channel = self.make_request( + "PUT", + "/_matrix/client/r0/rooms/%s/send/foo.bar.allowed/1" % room_id, + {}, + access_token=tok, + ) + self.render(request) + self.assertEquals(channel.result["code"], b"200", channel.result) + + request, channel = self.make_request( + "PUT", + "/_matrix/client/r0/rooms/%s/send/foo.bar.forbidden/1" % room_id, + {}, + access_token=tok, + ) + self.render(request) + self.assertEquals(channel.result["code"], b"403", channel.result)