diff --git a/synapse/federation/federation_base.py b/synapse/federation/federation_base.py
index c11798093d..5be8e66fb8 100644
--- a/synapse/federation/federation_base.py
+++ b/synapse/federation/federation_base.py
@@ -13,17 +13,20 @@
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
+from collections import namedtuple
import six
from twisted.internet import defer
+from twisted.internet.defer import DeferredList
-from synapse.api.constants import MAX_DEPTH
+from synapse.api.constants import MAX_DEPTH, EventTypes, Membership
from synapse.api.errors import Codes, SynapseError
from synapse.crypto.event_signing import check_event_content_hash
from synapse.events import FrozenEvent
from synapse.events.utils import prune_event
from synapse.http.servlet import assert_params_in_dict
+from synapse.types import get_domain_from_id
from synapse.util import logcontext, unwrapFirstError
logger = logging.getLogger(__name__)
@@ -133,34 +136,25 @@ class FederationBase(object):
* throws a SynapseError if the signature check failed.
The deferreds run their callbacks in the sentinel logcontext.
"""
-
- redacted_pdus = [
- prune_event(pdu)
- for pdu in pdus
- ]
-
- deferreds = self.keyring.verify_json_objects_for_server([
- (p.origin, p.get_pdu_json())
- for p in redacted_pdus
- ])
+ deferreds = _check_sigs_on_pdus(self.keyring, pdus)
ctx = logcontext.LoggingContext.current_context()
- def callback(_, pdu, redacted):
+ def callback(_, pdu):
with logcontext.PreserveLoggingContext(ctx):
if not check_event_content_hash(pdu):
logger.warn(
"Event content has been tampered, redacting %s: %s",
pdu.event_id, pdu.get_pdu_json()
)
- return redacted
+ return prune_event(pdu)
if self.spam_checker.check_event_for_spam(pdu):
logger.warn(
"Event contains spam, redacting %s: %s",
pdu.event_id, pdu.get_pdu_json()
)
- return redacted
+ return prune_event(pdu)
return pdu
@@ -173,16 +167,116 @@ class FederationBase(object):
)
return failure
- for deferred, pdu, redacted in zip(deferreds, pdus, redacted_pdus):
+ for deferred, pdu in zip(deferreds, pdus):
deferred.addCallbacks(
callback, errback,
- callbackArgs=[pdu, redacted],
+ callbackArgs=[pdu],
errbackArgs=[pdu],
)
return deferreds
+class PduToCheckSig(namedtuple("PduToCheckSig", [
+ "pdu", "redacted_pdu_json", "event_id_domain", "sender_domain", "deferreds",
+])):
+ pass
+
+
+def _check_sigs_on_pdus(keyring, pdus):
+ """Check that the given events are correctly signed
+
+ Args:
+ keyring (synapse.crypto.Keyring): keyring object to do the checks
+ pdus (Collection[EventBase]): the events to be checked
+
+ Returns:
+ List[Deferred]: a Deferred for each event in pdus, which will either succeed if
+ the signatures are valid, or fail (with a SynapseError) if not.
+ """
+
+ # (currently this is written assuming the v1 room structure; we'll probably want a
+ # separate function for checking v2 rooms)
+
+ # we want to check that the event is signed by:
+ #
+ # (a) the server which created the event_id
+ #
+ # (b) the sender's server.
+ #
+ # - except in the case of invites created from a 3pid invite, which are exempt
+ # from this check, because the sender has to match that of the original 3pid
+ # invite, but the event may come from a different HS, for reasons that I don't
+ # entirely grok (why do the senders have to match? and if they do, why doesn't the
+ # joining server ask the inviting server to do the switcheroo with
+ # exchange_third_party_invite?).
+ #
+ # That's pretty awful, since redacting such an invite will render it invalid
+ # (because it will then look like a regular invite without a valid signature),
+ # and signatures are *supposed* to be valid whether or not an event has been
+ # redacted. But this isn't the worst of the ways that 3pid invites are broken.
+ #
+ # let's start by getting the domain for each pdu, and flattening the event back
+ # to JSON.
+ pdus_to_check = [
+ PduToCheckSig(
+ pdu=p,
+ redacted_pdu_json=prune_event(p).get_pdu_json(),
+ event_id_domain=get_domain_from_id(p.event_id),
+ sender_domain=get_domain_from_id(p.sender),
+ deferreds=[],
+ )
+ for p in pdus
+ ]
+
+ # first make sure that the event is signed by the event_id's domain
+ deferreds = keyring.verify_json_objects_for_server([
+ (p.event_id_domain, p.redacted_pdu_json)
+ for p in pdus_to_check
+ ])
+
+ for p, d in zip(pdus_to_check, deferreds):
+ p.deferreds.append(d)
+
+ # now let's look for events where the sender's domain is different to the
+ # event id's domain (normally only the case for joins/leaves), and add additional
+ # checks.
+ pdus_to_check_sender = [
+ p for p in pdus_to_check
+ if p.sender_domain != p.event_id_domain and not _is_invite_via_3pid(p.pdu)
+ ]
+
+ more_deferreds = keyring.verify_json_objects_for_server([
+ (p.sender_domain, p.redacted_pdu_json)
+ for p in pdus_to_check_sender
+ ])
+
+ for p, d in zip(pdus_to_check_sender, more_deferreds):
+ p.deferreds.append(d)
+
+ # replace lists of deferreds with single Deferreds
+ return [_flatten_deferred_list(p.deferreds) for p in pdus_to_check]
+
+
+def _flatten_deferred_list(deferreds):
+ """Given a list of one or more deferreds, either return the single deferred, or
+ combine into a DeferredList.
+ """
+ if len(deferreds) > 1:
+ return DeferredList(deferreds, fireOnOneErrback=True, consumeErrors=True)
+ else:
+ assert len(deferreds) == 1
+ return deferreds[0]
+
+
+def _is_invite_via_3pid(event):
+ return (
+ event.type == EventTypes.Member
+ and event.membership == Membership.INVITE
+ and "third_party_invite" in event.content
+ )
+
+
def event_from_pdu_json(pdu_json, outlier=False):
"""Construct a FrozenEvent from an event json received over federation
|
