diff options
Diffstat (limited to 'synapse/handlers/e2e_keys.py')
| -rw-r--r-- | synapse/handlers/e2e_keys.py | 166 |
1 files changed, 150 insertions, 16 deletions
diff --git a/synapse/handlers/e2e_keys.py b/synapse/handlers/e2e_keys.py index 95a9d71f41..8f1bc0323c 100644 --- a/synapse/handlers/e2e_keys.py +++ b/synapse/handlers/e2e_keys.py @@ -54,19 +54,23 @@ class E2eKeysHandler(object): self._edu_updater = SigningKeyEduUpdater(hs, self) + federation_registry = hs.get_federation_registry() + self._is_master = hs.config.worker_app is None if not self._is_master: self._user_device_resync_client = ReplicationUserDevicesResyncRestServlet.make_client( hs ) + else: + # Only register this edu handler on master as it requires writing + # device updates to the db + # + # FIXME: switch to m.signing_key_update when MSC1756 is merged into the spec + federation_registry.register_edu_handler( + "org.matrix.signing_key_update", + self._edu_updater.incoming_signing_key_update, + ) - federation_registry = hs.get_federation_registry() - - # FIXME: switch to m.signing_key_update when MSC1756 is merged into the spec - federation_registry.register_edu_handler( - "org.matrix.signing_key_update", - self._edu_updater.incoming_signing_key_update, - ) # doesn't really work as part of the generic query API, because the # query request requires an object POST, but we abuse the # "query handler" interface. @@ -170,8 +174,8 @@ class E2eKeysHandler(object): """This is called when we are querying the device list of a user on a remote homeserver and their device list is not in the device list cache. If we share a room with this user and we're not querying for - specific user we will update the cache - with their device list.""" + specific user we will update the cache with their device list. + """ destination_query = remote_queries_not_in_cache[destination] @@ -957,13 +961,19 @@ class E2eKeysHandler(object): return signature_list, failures @defer.inlineCallbacks - def _get_e2e_cross_signing_verify_key(self, user_id, key_type, from_user_id=None): - """Fetch the cross-signing public key from storage and interpret it. + def _get_e2e_cross_signing_verify_key( + self, user_id: str, key_type: str, from_user_id: str = None + ): + """Fetch locally or remotely query for a cross-signing public key. + + First, attempt to fetch the cross-signing public key from storage. + If that fails, query the keys from the homeserver they belong to + and update our local copy. Args: - user_id (str): the user whose key should be fetched - key_type (str): the type of key to fetch - from_user_id (str): the user that we are fetching the keys for. + user_id: the user whose key should be fetched + key_type: the type of key to fetch + from_user_id: the user that we are fetching the keys for. This affects what signatures are fetched. Returns: @@ -972,16 +982,140 @@ class E2eKeysHandler(object): Raises: NotFoundError: if the key is not found + SynapseError: if `user_id` is invalid """ + user = UserID.from_string(user_id) key = yield self.store.get_e2e_cross_signing_key( user_id, key_type, from_user_id ) + + if key: + # We found a copy of this key in our database. Decode and return it + key_id, verify_key = get_verify_key_from_cross_signing_key(key) + return key, key_id, verify_key + + # If we couldn't find the key locally, and we're looking for keys of + # another user then attempt to fetch the missing key from the remote + # user's server. + # + # We may run into this in possible edge cases where a user tries to + # cross-sign a remote user, but does not share any rooms with them yet. + # Thus, we would not have their key list yet. We instead fetch the key, + # store it and notify clients of new, associated device IDs. + if self.is_mine(user) or key_type not in ["master", "self_signing"]: + # Note that master and self_signing keys are the only cross-signing keys we + # can request over federation + raise NotFoundError("No %s key found for %s" % (key_type, user_id)) + + ( + key, + key_id, + verify_key, + ) = yield self._retrieve_cross_signing_keys_for_remote_user(user, key_type) + if key is None: - logger.debug("no %s key found for %s", key_type, user_id) raise NotFoundError("No %s key found for %s" % (key_type, user_id)) - key_id, verify_key = get_verify_key_from_cross_signing_key(key) + return key, key_id, verify_key + @defer.inlineCallbacks + def _retrieve_cross_signing_keys_for_remote_user( + self, user: UserID, desired_key_type: str, + ): + """Queries cross-signing keys for a remote user and saves them to the database + + Only the key specified by `key_type` will be returned, while all retrieved keys + will be saved regardless + + Args: + user: The user to query remote keys for + desired_key_type: The type of key to receive. One of "master", "self_signing" + + Returns: + Deferred[Tuple[Optional[Dict], Optional[str], Optional[VerifyKey]]]: A tuple + of the retrieved key content, the key's ID and the matching VerifyKey. + If the key cannot be retrieved, all values in the tuple will instead be None. + """ + try: + remote_result = yield self.federation.query_user_devices( + user.domain, user.to_string() + ) + except Exception as e: + logger.warning( + "Unable to query %s for cross-signing keys of user %s: %s %s", + user.domain, + user.to_string(), + type(e), + e, + ) + return None, None, None + + # Process each of the retrieved cross-signing keys + desired_key = None + desired_key_id = None + desired_verify_key = None + retrieved_device_ids = [] + for key_type in ["master", "self_signing"]: + key_content = remote_result.get(key_type + "_key") + if not key_content: + continue + + # Ensure these keys belong to the correct user + if "user_id" not in key_content: + logger.warning( + "Invalid %s key retrieved, missing user_id field: %s", + key_type, + key_content, + ) + continue + if user.to_string() != key_content["user_id"]: + logger.warning( + "Found %s key of user %s when querying for keys of user %s", + key_type, + key_content["user_id"], + user.to_string(), + ) + continue + + # Validate the key contents + try: + # verify_key is a VerifyKey from signedjson, which uses + # .version to denote the portion of the key ID after the + # algorithm and colon, which is the device ID + key_id, verify_key = get_verify_key_from_cross_signing_key(key_content) + except ValueError as e: + logger.warning( + "Invalid %s key retrieved: %s - %s %s", + key_type, + key_content, + type(e), + e, + ) + continue + + # Note down the device ID attached to this key + retrieved_device_ids.append(verify_key.version) + + # If this is the desired key type, save it and its ID/VerifyKey + if key_type == desired_key_type: + desired_key = key_content + desired_verify_key = verify_key + desired_key_id = key_id + + # At the same time, store this key in the db for subsequent queries + yield self.store.set_e2e_cross_signing_key( + user.to_string(), key_type, key_content + ) + + # Notify clients that new devices for this user have been discovered + if retrieved_device_ids: + # XXX is this necessary? + yield self.device_handler.notify_device_update( + user.to_string(), retrieved_device_ids + ) + + return desired_key, desired_key_id, desired_verify_key + def _check_cross_signing_key(key, user_id, key_type, signing_key=None): """Check a cross-signing key uploaded by a user. Performs some basic sanity |