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