From 4b090cb27363b84abeb8bfedfe22ebc4e6e3f7a1 Mon Sep 17 00:00:00 2001 From: Matthew Hodgson Date: Mon, 22 Jan 2018 12:13:41 +0100 Subject: [PATCH] add federation_domain_whitelist gives a way to restrict which domains your HS is allowed to federate with. useful mainly for gracefully preventing a private but internet-connected HS from trying to federate to the wider public Matrix network --- synapse/api/errors.py | 26 ++++++++++++++++++++ synapse/config/server.py | 19 +++++++++++++++ synapse/federation/federation_client.py | 5 +++- synapse/federation/transaction_queue.py | 4 +++- synapse/federation/transport/client.py | 3 +++ synapse/federation/transport/server.py | 9 ++++++- synapse/handlers/device.py | 4 ++++ synapse/handlers/e2e_keys.py | 8 ++++++- synapse/handlers/federation.py | 4 ++++ synapse/http/matrixfederationclient.py | 28 +++++++++++++++++++++- synapse/rest/key/v2/remote_key_resource.py | 8 +++++++ synapse/rest/media/v1/media_repository.py | 22 +++++++++++++++-- synapse/util/retryutils.py | 12 ++++++++++ tests/utils.py | 1 + 14 files changed, 146 insertions(+), 7 deletions(-) diff --git a/synapse/api/errors.py b/synapse/api/errors.py index 79b35b3e7..071abb899 100644 --- a/synapse/api/errors.py +++ b/synapse/api/errors.py @@ -140,6 +140,32 @@ class RegistrationError(SynapseError): pass +class FederationDeniedError(SynapseError): + """An error raised when the server tries to federate with a server which + is not on its federation whitelist. + + Attributes: + destination (str): The destination which has been denied + """ + + def __init__(self, destination): + """Raised by federation client or server to indicate that we are + are deliberately not attempting to contact a given server because it is + not on our federation whitelist. + + Args: + destination (str): the domain in question + """ + + self.destination = destination + + super(FederationDeniedError, self).__init__( + code=403, + msg="Federation denied with %s." % (self.destination,), + errcode=Codes.FORBIDDEN, + ) + + class InteractiveAuthIncompleteError(Exception): """An error raised when UI auth is not yet complete diff --git a/synapse/config/server.py b/synapse/config/server.py index 436dd8a6f..b413a91c7 100644 --- a/synapse/config/server.py +++ b/synapse/config/server.py @@ -55,6 +55,15 @@ class ServerConfig(Config): "block_non_admin_invites", False, ) + federation_domain_whitelist = config.get( + "federation_domain_whitelist", [] + ) + # turn the whitelist into a hash for speed of lookup + self.federation_domain_whitelist = {} + for domain in federation_domain_whitelist: + self.federation_domain_whitelist[domain] = True + # FIXME: federation_domain_whitelist needs sytests + if self.public_baseurl is not None: if self.public_baseurl[-1] != '/': self.public_baseurl += '/' @@ -210,6 +219,16 @@ class ServerConfig(Config): # (except those sent by local server admins). The default is False. # block_non_admin_invites: True + # Restrict federation to the following whitelist of domains. + # N.B. we recommend also firewalling your federation listener to limit + # inbound federation traffic as early as possible, rather than relying + # purely on this application-layer restriction. + # + # federation_domain_whitelist: + # - lon.example.com + # - nyc.example.com + # - syd.example.com + # List of ports that Synapse should listen on, their purpose and their # configuration. listeners: diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py index b1fe03f70..22e1ba6ef 100644 --- a/synapse/federation/federation_client.py +++ b/synapse/federation/federation_client.py @@ -23,7 +23,7 @@ from twisted.internet import defer from synapse.api.constants import Membership from synapse.api.errors import ( - CodeMessageException, HttpResponseException, SynapseError, + CodeMessageException, HttpResponseException, SynapseError, FederationDeniedError ) from synapse.events import builder from synapse.federation.federation_base import ( @@ -266,6 +266,9 @@ class FederationClient(FederationBase): except NotRetryingDestination as e: logger.info(e.message) continue + except FederationDeniedError as e: + logger.debug(e.message) + continue except Exception as e: pdu_attempts[destination] = now diff --git a/synapse/federation/transaction_queue.py b/synapse/federation/transaction_queue.py index 9d39f4658..343e5f75a 100644 --- a/synapse/federation/transaction_queue.py +++ b/synapse/federation/transaction_queue.py @@ -19,7 +19,7 @@ from twisted.internet import defer from .persistence import TransactionActions from .units import Transaction, Edu -from synapse.api.errors import HttpResponseException +from synapse.api.errors import HttpResponseException, FederationDeniedError from synapse.util import logcontext, PreserveLoggingContext from synapse.util.async import run_on_reactor from synapse.util.retryutils import NotRetryingDestination, get_retry_limiter @@ -490,6 +490,8 @@ class TransactionQueue(object): (e.retry_last_ts + e.retry_interval) / 1000.0 ), ) + except FederationDeniedError as e: + logger.debug(e) except Exception as e: logger.warn( "TX [%s] Failed to send transaction: %s", diff --git a/synapse/federation/transport/client.py b/synapse/federation/transport/client.py index 1f3ce238f..5488e8298 100644 --- a/synapse/federation/transport/client.py +++ b/synapse/federation/transport/client.py @@ -212,6 +212,9 @@ class TransportLayerClient(object): Fails with ``NotRetryingDestination`` if we are not yet ready to retry this server. + + Fails with ``FederationDeniedError`` if the remote destination + is not in our federation whitelist """ valid_memberships = {Membership.JOIN, Membership.LEAVE} if membership not in valid_memberships: diff --git a/synapse/federation/transport/server.py b/synapse/federation/transport/server.py index 2b02b021e..38b445604 100644 --- a/synapse/federation/transport/server.py +++ b/synapse/federation/transport/server.py @@ -16,7 +16,7 @@ from twisted.internet import defer from synapse.api.urls import FEDERATION_PREFIX as PREFIX -from synapse.api.errors import Codes, SynapseError +from synapse.api.errors import Codes, SynapseError, FederationDeniedError from synapse.http.server import JsonResource from synapse.http.servlet import ( parse_json_object_from_request, parse_integer_from_args, parse_string_from_args, @@ -81,6 +81,7 @@ class Authenticator(object): self.keyring = hs.get_keyring() self.server_name = hs.hostname self.store = hs.get_datastore() + self.federation_domain_whitelist = hs.config.federation_domain_whitelist # A method just so we can pass 'self' as the authenticator to the Servlets @defer.inlineCallbacks @@ -92,6 +93,12 @@ class Authenticator(object): "signatures": {}, } + if ( + self.federation_domain_whitelist and + self.server_name not in self.federation_domain_whitelist + ): + raise FederationDeniedError(self.server_name) + if content is not None: json_request["content"] = content diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py index 2152efc69..7e150b19b 100644 --- a/synapse/handlers/device.py +++ b/synapse/handlers/device.py @@ -14,6 +14,7 @@ # limitations under the License. from synapse.api import errors from synapse.api.constants import EventTypes +from synapse.api.errors import FederationDeniedError from synapse.util import stringutils from synapse.util.async import Linearizer from synapse.util.caches.expiringcache import ExpiringCache @@ -513,6 +514,9 @@ class DeviceListEduUpdater(object): # This makes it more likely that the device lists will # eventually become consistent. return + except FederationDeniedError as e: + logger.debug(e) + return except Exception: # TODO: Remember that we are now out of sync and try again # later diff --git a/synapse/handlers/e2e_keys.py b/synapse/handlers/e2e_keys.py index 5af8abf66..9aa95f89e 100644 --- a/synapse/handlers/e2e_keys.py +++ b/synapse/handlers/e2e_keys.py @@ -19,7 +19,9 @@ import logging from canonicaljson import encode_canonical_json from twisted.internet import defer -from synapse.api.errors import SynapseError, CodeMessageException +from synapse.api.errors import ( + SynapseError, CodeMessageException, FederationDeniedError, +) from synapse.types import get_domain_from_id, UserID from synapse.util.logcontext import preserve_fn, make_deferred_yieldable from synapse.util.retryutils import NotRetryingDestination @@ -140,6 +142,10 @@ class E2eKeysHandler(object): failures[destination] = { "status": 503, "message": "Not ready for retry", } + except FederationDeniedError as e: + failures[destination] = { + "status": 403, "message": "Federation Denied", + } except Exception as e: # include ConnectionRefused and other errors failures[destination] = { diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py index ac7073088..c6344f322 100644 --- a/synapse/handlers/federation.py +++ b/synapse/handlers/federation.py @@ -22,6 +22,7 @@ from ._base import BaseHandler from synapse.api.errors import ( AuthError, FederationError, StoreError, CodeMessageException, SynapseError, + FederationDeniedError, ) from synapse.api.constants import EventTypes, Membership, RejectedReason from synapse.events.validator import EventValidator @@ -782,6 +783,9 @@ class FederationHandler(BaseHandler): except NotRetryingDestination as e: logger.info(e.message) continue + except FederationDeniedError as e: + logger.debug(e) + continue except Exception as e: logger.exception( "Failed to backfill from %s because %s", diff --git a/synapse/http/matrixfederationclient.py b/synapse/http/matrixfederationclient.py index 833496b72..9145405cb 100644 --- a/synapse/http/matrixfederationclient.py +++ b/synapse/http/matrixfederationclient.py @@ -27,7 +27,7 @@ import synapse.metrics from canonicaljson import encode_canonical_json from synapse.api.errors import ( - SynapseError, Codes, HttpResponseException, + SynapseError, Codes, HttpResponseException, FederationDeniedError, ) from signedjson.sign import sign_json @@ -123,11 +123,22 @@ class MatrixFederationHttpClient(object): Fails with ``HTTPRequestException``: if we get an HTTP response code >= 300. + Fails with ``NotRetryingDestination`` if we are not yet ready to retry this server. + + Fails with ``FederationDeniedError`` if this destination + is not on our federation whitelist + (May also fail with plenty of other Exceptions for things like DNS failures, connection failures, SSL failures.) """ + if ( + self.hs.config.federation_domain_whitelist and + destination not in self.hs.config.federation_domain_whitelist + ): + raise FederationDeniedError(destination) + limiter = yield synapse.util.retryutils.get_retry_limiter( destination, self.clock, @@ -308,6 +319,9 @@ class MatrixFederationHttpClient(object): Fails with ``NotRetryingDestination`` if we are not yet ready to retry this server. + + Fails with ``FederationDeniedError`` if this destination + is not on our federation whitelist """ if not json_data_callback: @@ -368,6 +382,9 @@ class MatrixFederationHttpClient(object): Fails with ``NotRetryingDestination`` if we are not yet ready to retry this server. + + Fails with ``FederationDeniedError`` if this destination + is not on our federation whitelist """ def body_callback(method, url_bytes, headers_dict): @@ -422,6 +439,9 @@ class MatrixFederationHttpClient(object): Fails with ``NotRetryingDestination`` if we are not yet ready to retry this server. + + Fails with ``FederationDeniedError`` if this destination + is not on our federation whitelist """ logger.debug("get_json args: %s", args) @@ -475,6 +495,9 @@ class MatrixFederationHttpClient(object): Fails with ``NotRetryingDestination`` if we are not yet ready to retry this server. + + Fails with ``FederationDeniedError`` if this destination + is not on our federation whitelist """ response = yield self._request( @@ -518,6 +541,9 @@ class MatrixFederationHttpClient(object): Fails with ``NotRetryingDestination`` if we are not yet ready to retry this server. + + Fails with ``FederationDeniedError`` if this destination + is not on our federation whitelist """ encoded_args = {} diff --git a/synapse/rest/key/v2/remote_key_resource.py b/synapse/rest/key/v2/remote_key_resource.py index cc2842aa7..94110bf59 100644 --- a/synapse/rest/key/v2/remote_key_resource.py +++ b/synapse/rest/key/v2/remote_key_resource.py @@ -93,6 +93,7 @@ class RemoteKey(Resource): self.store = hs.get_datastore() self.version_string = hs.version_string self.clock = hs.get_clock() + self.federation_domain_whitelist = hs.config.federation_domain_whitelist def render_GET(self, request): self.async_render_GET(request) @@ -137,6 +138,13 @@ class RemoteKey(Resource): logger.info("Handling query for keys %r", query) store_queries = [] for server_name, key_ids in query.items(): + if ( + self.federation_domain_whitelist and + server_name not in self.federation_domain_whitelist + ): + logger.debug("Federation denied with %s", server_name) + continue + if not key_ids: key_ids = (None,) for key_id in key_ids: diff --git a/synapse/rest/media/v1/media_repository.py b/synapse/rest/media/v1/media_repository.py index b2c76440b..7cd7a8ec1 100644 --- a/synapse/rest/media/v1/media_repository.py +++ b/synapse/rest/media/v1/media_repository.py @@ -34,8 +34,9 @@ from .media_storage import MediaStorage from synapse.http.matrixfederationclient import MatrixFederationHttpClient from synapse.util.stringutils import random_string -from synapse.api.errors import SynapseError, HttpResponseException, \ - NotFoundError +from synapse.api.errors import ( + SynapseError, HttpResponseException, NotFoundError, FederationDeniedError, +) from synapse.util.async import Linearizer from synapse.util.stringutils import is_ascii @@ -77,6 +78,8 @@ class MediaRepository(object): self.recently_accessed_remotes = set() self.recently_accessed_locals = set() + self.federation_domain_whitelist = hs.config.federation_domain_whitelist + # List of StorageProviders where we should search for media and # potentially upload to. storage_providers = [] @@ -222,6 +225,12 @@ class MediaRepository(object): Deferred: Resolves once a response has successfully been written to request """ + if ( + self.federation_domain_whitelist and + server_name not in self.federation_domain_whitelist + ): + raise FederationDeniedError(server_name) + self.mark_recently_accessed(server_name, media_id) # We linearize here to ensure that we don't try and download remote @@ -256,6 +265,12 @@ class MediaRepository(object): Returns: Deferred[dict]: The media_info of the file """ + if ( + self.federation_domain_whitelist and + server_name not in self.federation_domain_whitelist + ): + raise FederationDeniedError(server_name) + # We linearize here to ensure that we don't try and download remote # media multiple times concurrently key = (server_name, media_id) @@ -371,6 +386,9 @@ class MediaRepository(object): except NotRetryingDestination: logger.warn("Not retrying destination %r", server_name) raise SynapseError(502, "Failed to fetch remote media") + except FederationDeniedError as e: + logger.debug(e) + raise SynapseError(403, e.message) except Exception: logger.exception("Failed to fetch remote media %s/%s", server_name, media_id) diff --git a/synapse/util/retryutils.py b/synapse/util/retryutils.py index 1adedbb36..47b0bb5eb 100644 --- a/synapse/util/retryutils.py +++ b/synapse/util/retryutils.py @@ -26,6 +26,18 @@ logger = logging.getLogger(__name__) class NotRetryingDestination(Exception): def __init__(self, retry_last_ts, retry_interval, destination): + """Raised by the limiter (and federation client) to indicate that we are + are deliberately not attempting to contact a given server. + + Args: + retry_last_ts (int): the unix ts in milliseconds of our last attempt + to contact the server. 0 indicates that the last attempt was + successful or that we've never actually attempted to connect. + retry_interval (int): the time in milliseconds to wait until the next + attempt. + destination (str): the domain in question + """ + msg = "Not retrying server %s." % (destination,) super(NotRetryingDestination, self).__init__(msg) diff --git a/tests/utils.py b/tests/utils.py index 44e5f7509..5b043c91f 100644 --- a/tests/utils.py +++ b/tests/utils.py @@ -57,6 +57,7 @@ def setup_test_homeserver(name="test", datastore=None, config=None, **kargs): config.worker_app = None config.email_enable_notifs = False config.block_non_admin_invites = False + config.federation_domain_whitelist = {} # disable user directory updates, because they get done in the # background, which upsets the test runner.