diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index ac15f9e5dd..3655b9e5e2 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -14,6 +14,9 @@
# limitations under the License.
"""Contains handlers for federation events."""
+from signedjson.key import decode_verify_key_bytes
+from signedjson.sign import verify_signed_json
+from unpaddedbase64 import decode_base64
from ._base import BaseHandler
@@ -1620,19 +1623,15 @@ class FederationHandler(BaseHandler):
@defer.inlineCallbacks
@log_function
- def exchange_third_party_invite(self, invite):
- sender = invite["sender"]
- room_id = invite["room_id"]
-
- if "signed" not in invite or "token" not in invite["signed"]:
- logger.info(
- "Discarding received notification of third party invite "
- "without signed: %s" % (invite,)
- )
- return
-
+ def exchange_third_party_invite(
+ self,
+ sender_user_id,
+ target_user_id,
+ room_id,
+ signed,
+ ):
third_party_invite = {
- "signed": invite["signed"],
+ "signed": signed,
}
event_dict = {
@@ -1642,8 +1641,8 @@ class FederationHandler(BaseHandler):
"third_party_invite": third_party_invite,
},
"room_id": room_id,
- "sender": sender,
- "state_key": invite["mxid"],
+ "sender": sender_user_id,
+ "state_key": target_user_id,
}
if (yield self.auth.check_host_in_room(room_id, self.hs.hostname)):
@@ -1656,11 +1655,11 @@ class FederationHandler(BaseHandler):
)
self.auth.check(event, context.current_state)
- yield self._validate_keyserver(event, auth_events=context.current_state)
+ yield self._check_signature(event, auth_events=context.current_state)
member_handler = self.hs.get_handlers().room_member_handler
yield member_handler.send_membership_event(event, context, from_client=False)
else:
- destinations = set([x.split(":", 1)[-1] for x in (sender, room_id)])
+ destinations = set(x.split(":", 1)[-1] for x in (sender_user_id, room_id))
yield self.replication_layer.forward_third_party_invite(
destinations,
room_id,
@@ -1681,7 +1680,7 @@ class FederationHandler(BaseHandler):
)
self.auth.check(event, auth_events=context.current_state)
- yield self._validate_keyserver(event, auth_events=context.current_state)
+ yield self._check_signature(event, auth_events=context.current_state)
returned_invite = yield self.send_invite(origin, event)
# TODO: Make sure the signatures actually are correct.
@@ -1711,17 +1710,69 @@ class FederationHandler(BaseHandler):
defer.returnValue((event, context))
@defer.inlineCallbacks
- def _validate_keyserver(self, event, auth_events):
- token = event.content["third_party_invite"]["signed"]["token"]
+ def _check_signature(self, event, auth_events):
+ """
+ Checks that the signature in the event is consistent with its invite.
+ :param event (Event): The m.room.member event to check
+ :param auth_events (dict<(event type, state_key), event>)
+
+ :raises
+ AuthError if signature didn't match any keys, or key has been
+ revoked,
+ SynapseError if a transient error meant a key couldn't be checked
+ for revocation.
+ """
+ signed = event.content["third_party_invite"]["signed"]
+ token = signed["token"]
invite_event = auth_events.get(
(EventTypes.ThirdPartyInvite, token,)
)
+ if not invite_event:
+ raise AuthError(403, "Could not find invite")
+
+ last_exception = None
+ for public_key_object in self.hs.get_auth().get_public_keys(invite_event):
+ try:
+ for server, signature_block in signed["signatures"].items():
+ for key_name, encoded_signature in signature_block.items():
+ if not key_name.startswith("ed25519:"):
+ continue
+
+ public_key = public_key_object["public_key"]
+ verify_key = decode_verify_key_bytes(
+ key_name,
+ decode_base64(public_key)
+ )
+ verify_signed_json(signed, server, verify_key)
+ if "key_validity_url" in public_key_object:
+ yield self._check_key_revocation(
+ public_key,
+ public_key_object["key_validity_url"]
+ )
+ return
+ except Exception as e:
+ last_exception = e
+ raise last_exception
+
+ @defer.inlineCallbacks
+ def _check_key_revocation(self, public_key, url):
+ """
+ Checks whether public_key has been revoked.
+
+ :param public_key (str): base-64 encoded public key.
+ :param url (str): Key revocation URL.
+
+ :raises
+ AuthError if they key has been revoked.
+ SynapseError if a transient error meant a key couldn't be checked
+ for revocation.
+ """
try:
response = yield self.hs.get_simple_http_client().get_json(
- invite_event.content["key_validity_url"],
- {"public_key": invite_event.content["public_key"]}
+ url,
+ {"public_key": public_key}
)
except Exception:
raise SynapseError(
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