From 33f469ba19586bbafa0cf2c7d7c35463bdab87eb Mon Sep 17 00:00:00 2001 From: Richard van der Hoff Date: Tue, 1 May 2018 16:19:39 +0100 Subject: Apply some limits to depth to counter abuse * When creating a new event, cap its depth to 2^63 - 1 * When receiving events, reject any without a sensible depth As per https://docs.google.com/document/d/1I3fi2S-XnpO45qrpCsowZv8P8dHcNZ4fsBsbOW7KABI --- synapse/api/constants.py | 3 +++ 1 file changed, 3 insertions(+) (limited to 'synapse/api/constants.py') diff --git a/synapse/api/constants.py b/synapse/api/constants.py index 489efb7f86..5baba43966 100644 --- a/synapse/api/constants.py +++ b/synapse/api/constants.py @@ -16,6 +16,9 @@ """Contains constants from the specification.""" +# the "depth" field on events is limited to 2**63 - 1 +MAX_DEPTH = 2**63 - 1 + class Membership(object): -- cgit 1.4.1 From 3cf3e08a97f4617763ce10da4f127c0e21d7ff1d Mon Sep 17 00:00:00 2001 From: Richard van der Hoff Date: Wed, 4 Jul 2018 15:31:00 +0100 Subject: Implementation of server_acls ... as described at https://docs.google.com/document/d/1EttUVzjc2DWe2ciw4XPtNpUpIl9lWXGEsy2ewDS7rtw. --- synapse/api/constants.py | 2 + synapse/federation/federation_server.py | 150 ++++++++++++++++++++++++++++- synapse/federation/transport/server.py | 8 +- tests/federation/__init__.py | 0 tests/federation/test_federation_server.py | 57 +++++++++++ 5 files changed, 213 insertions(+), 4 deletions(-) create mode 100644 tests/federation/__init__.py create mode 100644 tests/federation/test_federation_server.py (limited to 'synapse/api/constants.py') diff --git a/synapse/api/constants.py b/synapse/api/constants.py index 5baba43966..4df930c8d1 100644 --- a/synapse/api/constants.py +++ b/synapse/api/constants.py @@ -76,6 +76,8 @@ class EventTypes(object): Topic = "m.room.topic" Name = "m.room.name" + ServerACL = "m.room.server_acl" + class RejectedReason(object): AUTH_ERROR = "auth_error" diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py index fe51ba6806..591d0026bf 100644 --- a/synapse/federation/federation_server.py +++ b/synapse/federation/federation_server.py @@ -14,10 +14,14 @@ # See the License for the specific language governing permissions and # limitations under the License. import logging +import re from canonicaljson import json +import six from twisted.internet import defer +from twisted.internet.abstract import isIPAddress +from synapse.api.constants import EventTypes from synapse.api.errors import AuthError, FederationError, SynapseError, NotFoundError from synapse.crypto.event_signing import compute_event_signature from synapse.federation.federation_base import ( @@ -27,6 +31,7 @@ from synapse.federation.federation_base import ( from synapse.federation.persistence import TransactionActions from synapse.federation.units import Edu, Transaction +from synapse.http.endpoint import parse_server_name from synapse.types import get_domain_from_id from synapse.util import async from synapse.util.caches.response_cache import ResponseCache @@ -74,6 +79,9 @@ class FederationServer(FederationBase): @log_function def on_backfill_request(self, origin, room_id, versions, limit): with (yield self._server_linearizer.queue((origin, room_id))): + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, room_id) + pdus = yield self.handler.on_backfill_request( origin, room_id, versions, limit ) @@ -134,6 +142,8 @@ class FederationServer(FederationBase): received_pdus_counter.inc(len(transaction.pdus)) + origin_host, _ = parse_server_name(transaction.origin) + pdus_by_room = {} for p in transaction.pdus: @@ -154,9 +164,21 @@ class FederationServer(FederationBase): # we can process different rooms in parallel (which is useful if they # require callouts to other servers to fetch missing events), but # impose a limit to avoid going too crazy with ram/cpu. + @defer.inlineCallbacks def process_pdus_for_room(room_id): logger.debug("Processing PDUs for %s", room_id) + try: + yield self.check_server_matches_acl(origin_host, room_id) + except AuthError as e: + logger.warn( + "Ignoring PDUs for room %s from banned server", room_id, + ) + for pdu in pdus_by_room[room_id]: + event_id = pdu.event_id + pdu_results[event_id] = e.error_dict() + return + for pdu in pdus_by_room[room_id]: event_id = pdu.event_id try: @@ -211,6 +233,9 @@ class FederationServer(FederationBase): if not event_id: raise NotImplementedError("Specify an event") + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, room_id) + in_room = yield self.auth.check_host_in_room(room_id, origin) if not in_room: raise AuthError(403, "Host not in room.") @@ -234,6 +259,9 @@ class FederationServer(FederationBase): if not event_id: raise NotImplementedError("Specify an event") + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, room_id) + in_room = yield self.auth.check_host_in_room(room_id, origin) if not in_room: raise AuthError(403, "Host not in room.") @@ -298,7 +326,9 @@ class FederationServer(FederationBase): defer.returnValue((200, resp)) @defer.inlineCallbacks - def on_make_join_request(self, room_id, user_id): + def on_make_join_request(self, origin, room_id, user_id): + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, room_id) pdu = yield self.handler.on_make_join_request(room_id, user_id) time_now = self._clock.time_msec() defer.returnValue({"event": pdu.get_pdu_json(time_now)}) @@ -306,6 +336,8 @@ class FederationServer(FederationBase): @defer.inlineCallbacks def on_invite_request(self, origin, content): pdu = event_from_pdu_json(content) + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, pdu.room_id) ret_pdu = yield self.handler.on_invite_request(origin, pdu) time_now = self._clock.time_msec() defer.returnValue((200, {"event": ret_pdu.get_pdu_json(time_now)})) @@ -314,6 +346,10 @@ class FederationServer(FederationBase): def on_send_join_request(self, origin, content): logger.debug("on_send_join_request: content: %s", content) pdu = event_from_pdu_json(content) + + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, pdu.room_id) + logger.debug("on_send_join_request: pdu sigs: %s", pdu.signatures) res_pdus = yield self.handler.on_send_join_request(origin, pdu) time_now = self._clock.time_msec() @@ -325,7 +361,9 @@ class FederationServer(FederationBase): })) @defer.inlineCallbacks - def on_make_leave_request(self, room_id, user_id): + def on_make_leave_request(self, origin, room_id, user_id): + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, room_id) pdu = yield self.handler.on_make_leave_request(room_id, user_id) time_now = self._clock.time_msec() defer.returnValue({"event": pdu.get_pdu_json(time_now)}) @@ -334,6 +372,10 @@ class FederationServer(FederationBase): def on_send_leave_request(self, origin, content): logger.debug("on_send_leave_request: content: %s", content) pdu = event_from_pdu_json(content) + + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, pdu.room_id) + logger.debug("on_send_leave_request: pdu sigs: %s", pdu.signatures) yield self.handler.on_send_leave_request(origin, pdu) defer.returnValue((200, {})) @@ -341,6 +383,9 @@ class FederationServer(FederationBase): @defer.inlineCallbacks def on_event_auth(self, origin, room_id, event_id): with (yield self._server_linearizer.queue((origin, room_id))): + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, room_id) + time_now = self._clock.time_msec() auth_pdus = yield self.handler.on_event_auth(event_id) res = { @@ -369,6 +414,9 @@ class FederationServer(FederationBase): Deferred: Results in `dict` with the same format as `content` """ with (yield self._server_linearizer.queue((origin, room_id))): + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, room_id) + auth_chain = [ event_from_pdu_json(e) for e in content["auth_chain"] @@ -442,6 +490,9 @@ class FederationServer(FederationBase): def on_get_missing_events(self, origin, room_id, earliest_events, latest_events, limit, min_depth): with (yield self._server_linearizer.queue((origin, room_id))): + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, room_id) + logger.info( "on_get_missing_events: earliest_events: %r, latest_events: %r," " limit: %d, min_depth: %d", @@ -579,6 +630,101 @@ class FederationServer(FederationBase): ) defer.returnValue(ret) + @defer.inlineCallbacks + def check_server_matches_acl(self, server_name, room_id): + """Check if the given server is allowed by the server ACLs in the room + + Args: + server_name (str): name of server, *without any port part* + room_id (str): ID of the room to check + + Raises: + AuthError if the server does not match the ACL + """ + state_ids = yield self.store.get_current_state_ids(room_id) + acl_event_id = state_ids.get((EventTypes.ServerACL, "")) + + if not acl_event_id: + return + + acl_event = yield self.store.get_event(acl_event_id) + if server_matches_acl_event(server_name, acl_event): + return + + raise AuthError(code=403, msg="Server is banned from room") + + +def server_matches_acl_event(server_name, acl_event): + """Check if the given server is allowed by the ACL event + + Args: + server_name (str): name of server, without any port part + acl_event (EventBase): m.room.server_acl event + + Returns: + bool: True if this server is allowed by the ACLs + """ + logger.debug("Checking %s against acl %s", server_name, acl_event.content) + + # first of all, check if literal IPs are blocked, and if so, whether the + # server name is a literal IP + allow_ip_literals = acl_event.content.get("allow_ip_literals", True) + if not isinstance(allow_ip_literals, bool): + logger.warn("Ignorning non-bool allow_ip_literals flag") + allow_ip_literals = True + if not allow_ip_literals: + # check for ipv6 literals. These start with '['. + if server_name[0] == '[': + return False + + # check for ipv4 literals. We can just lift the routine from twisted. + if isIPAddress(server_name): + return False + + # next, check the deny list + deny = acl_event.content.get("deny", []) + if not isinstance(deny, (list, tuple)): + logger.warn("Ignorning non-list deny ACL %s", deny) + deny = [] + for e in deny: + if _acl_entry_matches(server_name, e): + # logger.info("%s matched deny rule %s", server_name, e) + return False + + # then the allow list. + allow = acl_event.content.get("allow", []) + if not isinstance(allow, (list, tuple)): + logger.warn("Ignorning non-list allow ACL %s", allow) + allow = [] + for e in allow: + if _acl_entry_matches(server_name, e): + # logger.info("%s matched allow rule %s", server_name, e) + return True + + # everything else should be rejected. + # logger.info("%s fell through", server_name) + return False + + +def _acl_entry_matches(server_name, acl_entry): + if not isinstance(acl_entry, six.string_types): + logger.warn("Ignoring non-str ACL entry '%s' (is %s)", acl_entry, type(acl_entry)) + return False + regex = _glob_to_regex(acl_entry) + return regex.match(server_name) + + +def _glob_to_regex(glob): + res = '' + for c in glob: + if c == '*': + res = res + '.*' + elif c == '?': + res = res + '.' + else: + res = res + re.escape(c) + return re.compile(res + "\\Z", re.IGNORECASE) + class FederationHandlerRegistry(object): """Allows classes to register themselves as handlers for a given EDU or diff --git a/synapse/federation/transport/server.py b/synapse/federation/transport/server.py index e1fdcc89dc..c6d98d35cb 100644 --- a/synapse/federation/transport/server.py +++ b/synapse/federation/transport/server.py @@ -385,7 +385,9 @@ class FederationMakeJoinServlet(BaseFederationServlet): @defer.inlineCallbacks def on_GET(self, origin, content, query, context, user_id): - content = yield self.handler.on_make_join_request(context, user_id) + content = yield self.handler.on_make_join_request( + origin, context, user_id, + ) defer.returnValue((200, content)) @@ -394,7 +396,9 @@ class FederationMakeLeaveServlet(BaseFederationServlet): @defer.inlineCallbacks def on_GET(self, origin, content, query, context, user_id): - content = yield self.handler.on_make_leave_request(context, user_id) + content = yield self.handler.on_make_leave_request( + origin, context, user_id, + ) defer.returnValue((200, content)) diff --git a/tests/federation/__init__.py b/tests/federation/__init__.py new file mode 100644 index 0000000000..e69de29bb2 diff --git a/tests/federation/test_federation_server.py b/tests/federation/test_federation_server.py new file mode 100644 index 0000000000..4e8dc8fea0 --- /dev/null +++ b/tests/federation/test_federation_server.py @@ -0,0 +1,57 @@ +# -*- coding: utf-8 -*- +# Copyright 2018 New Vector Ltd +# +# 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. +import logging + +from synapse.events import FrozenEvent +from synapse.federation.federation_server import server_matches_acl_event +from tests import unittest + + +@unittest.DEBUG +class ServerACLsTestCase(unittest.TestCase): + def test_blacklisted_server(self): + e = _create_acl_event({ + "allow": ["*"], + "deny": ["evil.com"], + }) + logging.info("ACL event: %s", e.content) + + self.assertFalse(server_matches_acl_event("evil.com", e)) + self.assertFalse(server_matches_acl_event("EVIL.COM", e)) + + self.assertTrue(server_matches_acl_event("evil.com.au", e)) + self.assertTrue(server_matches_acl_event("honestly.not.evil.com", e)) + + def test_block_ip_literals(self): + e = _create_acl_event({ + "allow_ip_literals": False, + "allow": ["*"], + }) + logging.info("ACL event: %s", e.content) + + self.assertFalse(server_matches_acl_event("1.2.3.4", e)) + self.assertTrue(server_matches_acl_event("1a.2.3.4", e)) + self.assertFalse(server_matches_acl_event("[1:2::]", e)) + self.assertTrue(server_matches_acl_event("1:2:3:4", e)) + + +def _create_acl_event(content): + return FrozenEvent({ + "room_id": "!a:b", + "event_id": "$a:b", + "type": "m.room.server_acls", + "sender": "@a:b", + "content": content + }) -- cgit 1.4.1