diff options
Diffstat (limited to 'synapse/crypto')
| -rw-r--r-- | synapse/crypto/keyring.py | 133 |
1 files changed, 92 insertions, 41 deletions
diff --git a/synapse/crypto/keyring.py b/synapse/crypto/keyring.py index d6ad7f1772..c63f106cf3 100644 --- a/synapse/crypto/keyring.py +++ b/synapse/crypto/keyring.py @@ -17,6 +17,7 @@ import logging from collections import namedtuple +import six from six import raise_from from six.moves import urllib @@ -346,6 +347,7 @@ class KeyFetcher(object): Args: server_name_and_key_ids (iterable[Tuple[str, iterable[str]]]): list of (server_name, iterable[key_id]) tuples to fetch keys for + Note that the iterables may be iterated more than once. Returns: Deferred[dict[str, dict[str, synapse.storage.keys.FetchKeyResult|None]]]: @@ -391,8 +393,7 @@ class BaseV2KeyFetcher(object): POST /_matrix/key/v2/query. Checks that each signature in the response that claims to come from the origin - server is valid. (Does not check that there actually is such a signature, for - some reason.) + server is valid, and that there is at least one such signature. Stores the json in server_keys_json so that it can be used for future responses to /_matrix/key/v2/query. @@ -427,16 +428,25 @@ class BaseV2KeyFetcher(object): verify_key=verify_key, valid_until_ts=ts_valid_until_ms ) - # TODO: improve this signature checking server_name = response_json["server_name"] + verified = False for key_id in response_json["signatures"].get(server_name, {}): - if key_id not in verify_keys: + # each of the keys used for the signature must be present in the response + # json. + key = verify_keys.get(key_id) + if not key: raise KeyLookupError( - "Key response must include verification keys for all signatures" + "Key response is signed by key id %s:%s but that key is not " + "present in the response" % (server_name, key_id) ) - verify_signed_json( - response_json, server_name, verify_keys[key_id].verify_key + verify_signed_json(response_json, server_name, key.verify_key) + verified = True + + if not verified: + raise KeyLookupError( + "Key response for %s is not signed by the origin server" + % (server_name,) ) for key_id, key_data in response_json["old_verify_keys"].items(): @@ -546,7 +556,16 @@ class PerspectivesKeyFetcher(BaseV2KeyFetcher): Returns: Deferred[dict[str, dict[str, synapse.storage.keys.FetchKeyResult]]]: map from server_name -> key_id -> FetchKeyResult + + Raises: + KeyLookupError if there was an error processing the entire response from + the server """ + logger.info( + "Requesting keys %s from notary server %s", + server_names_and_key_ids, + perspective_name, + ) # TODO(mark): Set the minimum_valid_until_ts to that needed by # the events being validated or the current time if validating # an incoming request. @@ -575,40 +594,31 @@ class PerspectivesKeyFetcher(BaseV2KeyFetcher): time_now_ms = self.clock.time_msec() for response in query_response["server_keys"]: - if ( - u"signatures" not in response - or perspective_name not in response[u"signatures"] - ): + # do this first, so that we can give useful errors thereafter + server_name = response.get("server_name") + if not isinstance(server_name, six.string_types): raise KeyLookupError( - "Key response not signed by perspective server" - " %r" % (perspective_name,) + "Malformed response from key notary server %s: invalid server_name" + % (perspective_name,) ) - verified = False - for key_id in response[u"signatures"][perspective_name]: - if key_id in perspective_keys: - verify_signed_json( - response, perspective_name, perspective_keys[key_id] - ) - verified = True - - if not verified: - logging.info( - "Response from perspective server %r not signed with a" - " known key, signed with: %r, known keys: %r", + try: + processed_response = yield self._process_perspectives_response( perspective_name, - list(response[u"signatures"][perspective_name]), - list(perspective_keys), + perspective_keys, + response, + time_added_ms=time_now_ms, ) - raise KeyLookupError( - "Response not signed with a known key for perspective" - " server %r" % (perspective_name,) + except KeyLookupError as e: + logger.warning( + "Error processing response from key notary server %s for origin " + "server %s: %s", + perspective_name, + server_name, + e, ) - - processed_response = yield self.process_v2_response( - perspective_name, response, time_added_ms=time_now_ms - ) - server_name = response["server_name"] + # we continue to process the rest of the response + continue added_keys.extend( (server_name, key_id, key) for key_id, key in processed_response.items() @@ -621,6 +631,53 @@ class PerspectivesKeyFetcher(BaseV2KeyFetcher): defer.returnValue(keys) + def _process_perspectives_response( + self, perspective_name, perspective_keys, response, time_added_ms + ): + """Parse a 'Server Keys' structure from the result of a /key/query request + + Checks that the entry is correctly signed by the perspectives server, and then + passes over to process_v2_response + + Args: + perspective_name (str): the name of the notary server that produced this + result + + perspective_keys (dict[str, VerifyKey]): map of key_id->key for the + notary server + + response (dict): the json-decoded Server Keys response object + + time_added_ms (int): the timestamp to record in server_keys_json + + Returns: + Deferred[dict[str, FetchKeyResult]]: map from key_id to result object + """ + if ( + u"signatures" not in response + or perspective_name not in response[u"signatures"] + ): + raise KeyLookupError("Response not signed by the notary server") + + verified = False + for key_id in response[u"signatures"][perspective_name]: + if key_id in perspective_keys: + verify_signed_json(response, perspective_name, perspective_keys[key_id]) + verified = True + + if not verified: + raise KeyLookupError( + "Response not signed with a known key: signed with: %r, known keys: %r" + % ( + list(response[u"signatures"][perspective_name].keys()), + list(perspective_keys.keys()), + ) + ) + + return self.process_v2_response( + perspective_name, response, time_added_ms=time_added_ms + ) + class ServerKeyFetcher(BaseV2KeyFetcher): """KeyFetcher impl which fetches keys from the origin servers""" @@ -674,12 +731,6 @@ class ServerKeyFetcher(BaseV2KeyFetcher): except HttpResponseException as e: raise_from(KeyLookupError("Remote server returned an error"), e) - if ( - u"signatures" not in response - or server_name not in response[u"signatures"] - ): - raise KeyLookupError("Key response not signed by remote server") - if response["server_name"] != server_name: raise KeyLookupError( "Expected a response for server %r not %r" |