Add federation_domain_whitelist option (#2820)

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

2 files changed, 25 insertions, 2 deletions

diff --git a/synapse/rest/key/v2/remote_key_resource.py b/synapse/rest/key/v2/remote_key_resource.py
index cc2842aa72..17e6079cba 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 is not None 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 4f56bcf577..485db8577a 100644
--- a/synapse/rest/media/v1/media_repository.py
+++ b/synapse/rest/media/v1/media_repository.py
@@ -32,8 +32,9 @@ 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
@@ -75,6 +76,8 @@ 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 = []
@@ -216,6 +219,12 @@ class MediaRepository(object):
             Deferred: Resolves once a response has successfully been written
                 to request
         """
+        if (
+            self.federation_domain_whitelist is not None 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
@@ -250,6 +259,12 @@ class MediaRepository(object):
         Returns:
             Deferred[dict]: The media_info of the file
         """
+        if (
+            self.federation_domain_whitelist is not None 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)