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-rw-r--r--synapse/api/errors.py27
-rw-r--r--synapse/config/registration.py19
-rw-r--r--synapse/config/server.py22
-rw-r--r--synapse/federation/federation_client.py5
-rw-r--r--synapse/federation/transaction_queue.py4
-rw-r--r--synapse/federation/transport/client.py3
-rw-r--r--synapse/federation/transport/server.py9
-rw-r--r--synapse/handlers/device.py4
-rw-r--r--synapse/handlers/e2e_keys.py8
-rw-r--r--synapse/handlers/federation.py4
-rw-r--r--synapse/handlers/register.py8
-rw-r--r--synapse/http/matrixfederationclient.py28
-rw-r--r--synapse/rest/client/v1/register.py34
-rw-r--r--synapse/rest/client/v1/room.py17
-rw-r--r--synapse/rest/client/v2_alpha/account.py21
-rw-r--r--synapse/rest/client/v2_alpha/register.py69
-rw-r--r--synapse/rest/key/v2/remote_key_resource.py8
-rw-r--r--synapse/rest/media/v1/media_repository.py19
-rw-r--r--synapse/util/retryutils.py12
-rw-r--r--synapse/util/threepids.py48
-rw-r--r--tests/replication/slave/storage/_base.py8
-rw-r--r--tests/rest/client/v2_alpha/test_register.py1
-rw-r--r--tests/utils.py1
23 files changed, 341 insertions, 38 deletions
diff --git a/synapse/api/errors.py b/synapse/api/errors.py
index 79b35b3e7c..aa15f73f36 100644
--- a/synapse/api/errors.py
+++ b/synapse/api/errors.py
@@ -46,6 +46,7 @@ class Codes(object):
     THREEPID_AUTH_FAILED = "M_THREEPID_AUTH_FAILED"
     THREEPID_IN_USE = "M_THREEPID_IN_USE"
     THREEPID_NOT_FOUND = "M_THREEPID_NOT_FOUND"
+    THREEPID_DENIED = "M_THREEPID_DENIED"
     INVALID_USERNAME = "M_INVALID_USERNAME"
     SERVER_NOT_TRUSTED = "M_SERVER_NOT_TRUSTED"
 
@@ -140,6 +141,32 @@ 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/registration.py b/synapse/config/registration.py
index ef917fc9f2..336959094b 100644
--- a/synapse/config/registration.py
+++ b/synapse/config/registration.py
@@ -31,6 +31,8 @@ class RegistrationConfig(Config):
                 strtobool(str(config["disable_registration"]))
             )
 
+        self.registrations_require_3pid = config.get("registrations_require_3pid", [])
+        self.allowed_local_3pids = config.get("allowed_local_3pids", [])
         self.registration_shared_secret = config.get("registration_shared_secret")
 
         self.bcrypt_rounds = config.get("bcrypt_rounds", 12)
@@ -52,6 +54,23 @@ class RegistrationConfig(Config):
         # Enable registration for new users.
         enable_registration: False
 
+        # The user must provide all of the below types of 3PID when registering.
+        #
+        # registrations_require_3pid:
+        #     - email
+        #     - msisdn
+
+        # Mandate that users are only allowed to associate certain formats of
+        # 3PIDs with accounts on this server.
+        #
+        # allowed_local_3pids:
+        #     - medium: email
+        #       pattern: ".*@matrix\\.org"
+        #     - medium: email
+        #       pattern: ".*@vector\\.im"
+        #     - medium: msisdn
+        #       pattern: "\\+44"
+
         # If set, allows registration by anyone who also has the shared
         # secret, even if registration is otherwise disabled.
         registration_shared_secret: "%(registration_shared_secret)s"
diff --git a/synapse/config/server.py b/synapse/config/server.py
index 436dd8a6fe..8f0b6d1f28 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -55,6 +55,17 @@ class ServerConfig(Config):
             "block_non_admin_invites", False,
         )
 
+        # FIXME: federation_domain_whitelist needs sytests
+        self.federation_domain_whitelist = None
+        federation_domain_whitelist = config.get(
+            "federation_domain_whitelist", None
+        )
+        # turn the whitelist into a hash for speed of lookup
+        if federation_domain_whitelist is not None:
+            self.federation_domain_whitelist = {}
+            for domain in federation_domain_whitelist:
+                self.federation_domain_whitelist[domain] = True
+
         if self.public_baseurl is not None:
             if self.public_baseurl[-1] != '/':
                 self.public_baseurl += '/'
@@ -210,6 +221,17 @@ 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.  If not specified, the
+        # default is to whitelist everything.
+        #
+        # 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 b1fe03f702..813907f7f2 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.info(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 9d39f46583..a141ec9953 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.info(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 1f3ce238f6..5488e82985 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 2b02b021ec..06c16ba4fa 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 is not None 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 2152efc692..0e83453851 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.info(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 5af8abf66b..9aa95f89e6 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 ac70730885..677532c87b 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.info(e)
+                    continue
                 except Exception as e:
                     logger.exception(
                         "Failed to backfill from %s because %s",
diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
index 5b808beac1..9021d4d57f 100644
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -25,6 +25,7 @@ from synapse.http.client import CaptchaServerHttpClient
 from synapse import types
 from synapse.types import UserID
 from synapse.util.async import run_on_reactor
+from synapse.util.threepids import check_3pid_allowed
 from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
@@ -293,7 +294,7 @@ class RegistrationHandler(BaseHandler):
         """
 
         for c in threepidCreds:
-            logger.info("validating theeepidcred sid %s on id server %s",
+            logger.info("validating threepidcred sid %s on id server %s",
                         c['sid'], c['idServer'])
             try:
                 identity_handler = self.hs.get_handlers().identity_handler
@@ -307,6 +308,11 @@ class RegistrationHandler(BaseHandler):
             logger.info("got threepid with medium '%s' and address '%s'",
                         threepid['medium'], threepid['address'])
 
+            if not check_3pid_allowed(self.hs, threepid['medium'], threepid['address']):
+                raise RegistrationError(
+                    403, "Third party identifier is not allowed"
+                )
+
     @defer.inlineCallbacks
     def bind_emails(self, user_id, threepidCreds):
         """Links emails with a user ID and informs an identity server.
diff --git a/synapse/http/matrixfederationclient.py b/synapse/http/matrixfederationclient.py
index 833496b72d..9145405cb0 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/client/v1/register.py b/synapse/rest/client/v1/register.py
index 32ed1d3ab2..5c5fa8f7ab 100644
--- a/synapse/rest/client/v1/register.py
+++ b/synapse/rest/client/v1/register.py
@@ -70,10 +70,15 @@ class RegisterRestServlet(ClientV1RestServlet):
         self.handlers = hs.get_handlers()
 
     def on_GET(self, request):
+
+        require_email = 'email' in self.hs.config.registrations_require_3pid
+        require_msisdn = 'msisdn' in self.hs.config.registrations_require_3pid
+
+        flows = []
         if self.hs.config.enable_registration_captcha:
-            return (
-                200,
-                {"flows": [
+            # only support the email-only flow if we don't require MSISDN 3PIDs
+            if not require_msisdn:
+                flows.extend([
                     {
                         "type": LoginType.RECAPTCHA,
                         "stages": [
@@ -82,27 +87,34 @@ class RegisterRestServlet(ClientV1RestServlet):
                             LoginType.PASSWORD
                         ]
                     },
+                ])
+            # only support 3PIDless registration if no 3PIDs are required
+            if not require_email and not require_msisdn:
+                flows.extend([
                     {
                         "type": LoginType.RECAPTCHA,
                         "stages": [LoginType.RECAPTCHA, LoginType.PASSWORD]
                     }
-                ]}
-            )
+                ])
         else:
-            return (
-                200,
-                {"flows": [
+            # only support the email-only flow if we don't require MSISDN 3PIDs
+            if require_email or not require_msisdn:
+                flows.extend([
                     {
                         "type": LoginType.EMAIL_IDENTITY,
                         "stages": [
                             LoginType.EMAIL_IDENTITY, LoginType.PASSWORD
                         ]
-                    },
+                    }
+                ])
+            # only support 3PIDless registration if no 3PIDs are required
+            if not require_email and not require_msisdn:
+                flows.extend([
                     {
                         "type": LoginType.PASSWORD
                     }
-                ]}
-            )
+                ])
+        return (200, {"flows": flows})
 
     @defer.inlineCallbacks
     def on_POST(self, request):
diff --git a/synapse/rest/client/v1/room.py b/synapse/rest/client/v1/room.py
index 682a0af9fc..867ec8602c 100644
--- a/synapse/rest/client/v1/room.py
+++ b/synapse/rest/client/v1/room.py
@@ -195,15 +195,20 @@ class RoomSendEventRestServlet(ClientV1RestServlet):
         requester = yield self.auth.get_user_by_req(request, allow_guest=True)
         content = parse_json_object_from_request(request)
 
+        event_dict = {
+            "type": event_type,
+            "content": content,
+            "room_id": room_id,
+            "sender": requester.user.to_string(),
+        }
+
+        if 'ts' in request.args and requester.app_service:
+            event_dict['origin_server_ts'] = parse_integer(request, "ts", 0)
+
         msg_handler = self.handlers.message_handler
         event = yield msg_handler.create_and_send_nonmember_event(
             requester,
-            {
-                "type": event_type,
-                "content": content,
-                "room_id": room_id,
-                "sender": requester.user.to_string(),
-            },
+            event_dict,
             txn_id=txn_id,
         )
 
diff --git a/synapse/rest/client/v2_alpha/account.py b/synapse/rest/client/v2_alpha/account.py
index 385a3ad2ec..30523995af 100644
--- a/synapse/rest/client/v2_alpha/account.py
+++ b/synapse/rest/client/v2_alpha/account.py
@@ -26,6 +26,7 @@ from synapse.http.servlet import (
 )
 from synapse.util.async import run_on_reactor
 from synapse.util.msisdn import phone_number_to_msisdn
+from synapse.util.threepids import check_3pid_allowed
 from ._base import client_v2_patterns, interactive_auth_handler
 
 logger = logging.getLogger(__name__)
@@ -47,6 +48,11 @@ class EmailPasswordRequestTokenRestServlet(RestServlet):
             'id_server', 'client_secret', 'email', 'send_attempt'
         ])
 
+        if not check_3pid_allowed(self.hs, "email", body['email']):
+            raise SynapseError(
+                403, "Third party identifier is not allowed", Codes.THREEPID_DENIED,
+            )
+
         existingUid = yield self.hs.get_datastore().get_user_id_by_threepid(
             'email', body['email']
         )
@@ -78,6 +84,11 @@ class MsisdnPasswordRequestTokenRestServlet(RestServlet):
 
         msisdn = phone_number_to_msisdn(body['country'], body['phone_number'])
 
+        if not check_3pid_allowed(self.hs, "msisdn", msisdn):
+            raise SynapseError(
+                403, "Third party identifier is not allowed", Codes.THREEPID_DENIED,
+            )
+
         existingUid = yield self.datastore.get_user_id_by_threepid(
             'msisdn', msisdn
         )
@@ -217,6 +228,11 @@ class EmailThreepidRequestTokenRestServlet(RestServlet):
         if absent:
             raise SynapseError(400, "Missing params: %r" % absent, Codes.MISSING_PARAM)
 
+        if not check_3pid_allowed(self.hs, "email", body['email']):
+            raise SynapseError(
+                403, "Third party identifier is not allowed", Codes.THREEPID_DENIED,
+            )
+
         existingUid = yield self.datastore.get_user_id_by_threepid(
             'email', body['email']
         )
@@ -255,6 +271,11 @@ class MsisdnThreepidRequestTokenRestServlet(RestServlet):
 
         msisdn = phone_number_to_msisdn(body['country'], body['phone_number'])
 
+        if not check_3pid_allowed(self.hs, "msisdn", msisdn):
+            raise SynapseError(
+                403, "Third party identifier is not allowed", Codes.THREEPID_DENIED,
+            )
+
         existingUid = yield self.datastore.get_user_id_by_threepid(
             'msisdn', msisdn
         )
diff --git a/synapse/rest/client/v2_alpha/register.py b/synapse/rest/client/v2_alpha/register.py
index e9d88a8895..3abfe35479 100644
--- a/synapse/rest/client/v2_alpha/register.py
+++ b/synapse/rest/client/v2_alpha/register.py
@@ -26,6 +26,7 @@ from synapse.http.servlet import (
     RestServlet, parse_json_object_from_request, assert_params_in_request, parse_string
 )
 from synapse.util.msisdn import phone_number_to_msisdn
+from synapse.util.threepids import check_3pid_allowed
 
 from ._base import client_v2_patterns, interactive_auth_handler
 
@@ -70,6 +71,11 @@ class EmailRegisterRequestTokenRestServlet(RestServlet):
             'id_server', 'client_secret', 'email', 'send_attempt'
         ])
 
+        if not check_3pid_allowed(self.hs, "email", body['email']):
+            raise SynapseError(
+                403, "Third party identifier is not allowed", Codes.THREEPID_DENIED,
+            )
+
         existingUid = yield self.hs.get_datastore().get_user_id_by_threepid(
             'email', body['email']
         )
@@ -105,6 +111,11 @@ class MsisdnRegisterRequestTokenRestServlet(RestServlet):
 
         msisdn = phone_number_to_msisdn(body['country'], body['phone_number'])
 
+        if not check_3pid_allowed(self.hs, "msisdn", msisdn):
+            raise SynapseError(
+                403, "Third party identifier is not allowed", Codes.THREEPID_DENIED,
+            )
+
         existingUid = yield self.hs.get_datastore().get_user_id_by_threepid(
             'msisdn', msisdn
         )
@@ -305,31 +316,67 @@ class RegisterRestServlet(RestServlet):
         if 'x_show_msisdn' in body and body['x_show_msisdn']:
             show_msisdn = True
 
+        # FIXME: need a better error than "no auth flow found" for scenarios
+        # where we required 3PID for registration but the user didn't give one
+        require_email = 'email' in self.hs.config.registrations_require_3pid
+        require_msisdn = 'msisdn' in self.hs.config.registrations_require_3pid
+
+        flows = []
         if self.hs.config.enable_registration_captcha:
-            flows = [
-                [LoginType.RECAPTCHA],
-                [LoginType.EMAIL_IDENTITY, LoginType.RECAPTCHA],
-            ]
+            # only support 3PIDless registration if no 3PIDs are required
+            if not require_email and not require_msisdn:
+                flows.extend([[LoginType.RECAPTCHA]])
+            # only support the email-only flow if we don't require MSISDN 3PIDs
+            if not require_msisdn:
+                flows.extend([[LoginType.EMAIL_IDENTITY, LoginType.RECAPTCHA]])
+
             if show_msisdn:
+                # only support the MSISDN-only flow if we don't require email 3PIDs
+                if not require_email:
+                    flows.extend([[LoginType.MSISDN, LoginType.RECAPTCHA]])
+                # always let users provide both MSISDN & email
                 flows.extend([
-                    [LoginType.MSISDN, LoginType.RECAPTCHA],
                     [LoginType.MSISDN, LoginType.EMAIL_IDENTITY, LoginType.RECAPTCHA],
                 ])
         else:
-            flows = [
-                [LoginType.DUMMY],
-                [LoginType.EMAIL_IDENTITY],
-            ]
+            # only support 3PIDless registration if no 3PIDs are required
+            if not require_email and not require_msisdn:
+                flows.extend([[LoginType.DUMMY]])
+            # only support the email-only flow if we don't require MSISDN 3PIDs
+            if not require_msisdn:
+                flows.extend([[LoginType.EMAIL_IDENTITY]])
+
             if show_msisdn:
+                # only support the MSISDN-only flow if we don't require email 3PIDs
+                if not require_email or require_msisdn:
+                    flows.extend([[LoginType.MSISDN]])
+                # always let users provide both MSISDN & email
                 flows.extend([
-                    [LoginType.MSISDN],
-                    [LoginType.MSISDN, LoginType.EMAIL_IDENTITY],
+                    [LoginType.MSISDN, LoginType.EMAIL_IDENTITY]
                 ])
 
         auth_result, params, session_id = yield self.auth_handler.check_auth(
             flows, body, self.hs.get_ip_from_request(request)
         )
 
+        # Check that we're not trying to register a denied 3pid.
+        #
+        # the user-facing checks will probably already have happened in
+        # /register/email/requestToken when we requested a 3pid, but that's not
+        # guaranteed.
+
+        if auth_result:
+            for login_type in [LoginType.EMAIL_IDENTITY, LoginType.MSISDN]:
+                if login_type in auth_result:
+                    medium = auth_result[login_type].threepid['medium']
+                    address = auth_result[login_type].threepid['address']
+
+                    if not check_3pid_allowed(self.hs, medium, address):
+                        raise SynapseError(
+                            403, "Third party identifier is not allowed",
+                            Codes.THREEPID_DENIED,
+                        )
+
         if registered_user_id is not None:
             logger.info(
                 "Already registered user ID %r for this session",
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)
diff --git a/synapse/util/retryutils.py b/synapse/util/retryutils.py
index 1adedbb361..47b0bb5eb3 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/synapse/util/threepids.py b/synapse/util/threepids.py
new file mode 100644
index 0000000000..75efa0117b
--- /dev/null
+++ b/synapse/util/threepids.py
@@ -0,0 +1,48 @@
+# -*- 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
+import re
+
+logger = logging.getLogger(__name__)
+
+
+def check_3pid_allowed(hs, medium, address):
+    """Checks whether a given format of 3PID is allowed to be used on this HS
+
+    Args:
+        hs (synapse.server.HomeServer): server
+        medium (str): 3pid medium - e.g. email, msisdn
+        address (str): address within that medium (e.g. "wotan@matrix.org")
+            msisdns need to first have been canonicalised
+    Returns:
+        bool: whether the 3PID medium/address is allowed to be added to this HS
+    """
+
+    if hs.config.allowed_local_3pids:
+        for constraint in hs.config.allowed_local_3pids:
+            logger.debug(
+                "Checking 3PID %s (%s) against %s (%s)",
+                address, medium, constraint['pattern'], constraint['medium'],
+            )
+            if (
+                medium == constraint['medium'] and
+                re.match(constraint['pattern'], address)
+            ):
+                return True
+    else:
+        return True
+
+    return False
diff --git a/tests/replication/slave/storage/_base.py b/tests/replication/slave/storage/_base.py
index 81063f19a1..74f104e3b8 100644
--- a/tests/replication/slave/storage/_base.py
+++ b/tests/replication/slave/storage/_base.py
@@ -15,6 +15,8 @@
 from twisted.internet import defer, reactor
 from tests import unittest
 
+import tempfile
+
 from mock import Mock, NonCallableMock
 from tests.utils import setup_test_homeserver
 from synapse.replication.tcp.resource import ReplicationStreamProtocolFactory
@@ -41,7 +43,9 @@ class BaseSlavedStoreTestCase(unittest.TestCase):
         self.event_id = 0
 
         server_factory = ReplicationStreamProtocolFactory(self.hs)
-        listener = reactor.listenUNIX("\0xxx", server_factory)
+        # XXX: mktemp is unsafe and should never be used. but we're just a test.
+        path = tempfile.mktemp(prefix="base_slaved_store_test_case_socket")
+        listener = reactor.listenUNIX(path, server_factory)
         self.addCleanup(listener.stopListening)
         self.streamer = server_factory.streamer
 
@@ -49,7 +53,7 @@ class BaseSlavedStoreTestCase(unittest.TestCase):
         client_factory = ReplicationClientFactory(
             self.hs, "client_name", self.replication_handler
         )
-        client_connector = reactor.connectUNIX("\0xxx", client_factory)
+        client_connector = reactor.connectUNIX(path, client_factory)
         self.addCleanup(client_factory.stopTrying)
         self.addCleanup(client_connector.disconnect)
 
diff --git a/tests/rest/client/v2_alpha/test_register.py b/tests/rest/client/v2_alpha/test_register.py
index 096f771bea..8aba456510 100644
--- a/tests/rest/client/v2_alpha/test_register.py
+++ b/tests/rest/client/v2_alpha/test_register.py
@@ -49,6 +49,7 @@ class RegisterRestServletTestCase(unittest.TestCase):
         self.hs.get_auth_handler = Mock(return_value=self.auth_handler)
         self.hs.get_device_handler = Mock(return_value=self.device_handler)
         self.hs.config.enable_registration = True
+        self.hs.config.registrations_require_3pid = []
         self.hs.config.auto_join_rooms = []
 
         # init the thing we're testing
diff --git a/tests/utils.py b/tests/utils.py
index 44e5f75093..3116047892 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 = None
 
         # disable user directory updates, because they get done in the
         # background, which upsets the test runner.