# -*- coding: utf-8 -*- # Copyright 2016 OpenMarket Ltd # Copyright 2018-2019 New Vector Ltd # Copyright 2019 The Matrix.org Foundation C.I.C. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. import logging from six import iteritems import attr from canonicaljson import encode_canonical_json, json from signedjson.key import decode_verify_key_bytes from signedjson.sign import SignatureVerifyException, verify_signed_json from unpaddedbase64 import decode_base64 from twisted.internet import defer from synapse.api.errors import ( CodeMessageException, Codes, NotFoundError, SynapseError, ) from synapse.logging.context import make_deferred_yieldable, run_in_background from synapse.logging.opentracing import log_kv, set_tag, tag_args, trace from synapse.replication.http.devices import ReplicationUserDevicesResyncRestServlet from synapse.types import ( UserID, get_domain_from_id, get_verify_key_from_cross_signing_key, ) from synapse.util import unwrapFirstError from synapse.util.async_helpers import Linearizer from synapse.util.caches.expiringcache import ExpiringCache from synapse.util.retryutils import NotRetryingDestination logger = logging.getLogger(__name__) class E2eKeysHandler(object): def __init__(self, hs): self.store = hs.get_datastore() self.federation = hs.get_federation_client() self.device_handler = hs.get_device_handler() self.is_mine = hs.is_mine self.clock = hs.get_clock() 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, ) # 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. federation_registry.register_query_handler( "client_keys", self.on_federation_query_client_keys ) @trace @defer.inlineCallbacks def query_devices(self, query_body, timeout, from_user_id): """ Handle a device key query from a client { "device_keys": { "": [""] } } -> { "device_keys": { "": { "": { ... } } } } Args: from_user_id (str): the user making the query. This is used when adding cross-signing signatures to limit what signatures users can see. """ device_keys_query = query_body.get("device_keys", {}) # separate users by domain. # make a map from domain to user_id to device_ids local_query = {} remote_queries = {} for user_id, device_ids in device_keys_query.items(): # we use UserID.from_string to catch invalid user ids if self.is_mine(UserID.from_string(user_id)): local_query[user_id] = device_ids else: remote_queries[user_id] = device_ids set_tag("local_key_query", local_query) set_tag("remote_key_query", remote_queries) # First get local devices. failures = {} results = {} if local_query: local_result = yield self.query_local_devices(local_query) for user_id, keys in local_result.items(): if user_id in local_query: results[user_id] = keys # Now attempt to get any remote devices from our local cache. remote_queries_not_in_cache = {} if remote_queries: query_list = [] for user_id, device_ids in iteritems(remote_queries): if device_ids: query_list.extend((user_id, device_id) for device_id in device_ids) else: query_list.append((user_id, None)) ( user_ids_not_in_cache, remote_results, ) = yield self.store.get_user_devices_from_cache(query_list) for user_id, devices in iteritems(remote_results): user_devices = results.setdefault(user_id, {}) for device_id, device in iteritems(devices): keys = device.get("keys", None) device_display_name = device.get("device_display_name", None) if keys: result = dict(keys) unsigned = result.setdefault("unsigned", {}) if device_display_name: unsigned["device_display_name"] = device_display_name user_devices[device_id] = result for user_id in user_ids_not_in_cache: domain = get_domain_from_id(user_id) r = remote_queries_not_in_cache.setdefault(domain, {}) r[user_id] = remote_queries[user_id] # Get cached cross-signing keys cross_signing_keys = yield self.get_cross_signing_keys_from_cache( device_keys_query, from_user_id ) # Now fetch any devices that we don't have in our cache @trace @defer.inlineCallbacks def do_remote_query(destination): """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. """ destination_query = remote_queries_not_in_cache[destination] # We first consider whether we wish to update the device list cache with # the users device list. We want to track a user's devices when the # authenticated user shares a room with the queried user and the query # has not specified a particular device. # If we update the cache for the queried user we remove them from further # queries. We use the more efficient batched query_client_keys for all # remaining users user_ids_updated = [] for (user_id, device_list) in destination_query.items(): if user_id in user_ids_updated: continue if device_list: continue room_ids = yield self.store.get_rooms_for_user(user_id) if not room_ids: continue # We've decided we're sharing a room with this user and should # probably be tracking their device lists. However, we haven't # done an initial sync on the device list so we do it now. try: if self._is_master: user_devices = yield self.device_handler.device_list_updater.user_device_resync( user_id ) else: user_devices = yield self._user_device_resync_client( user_id=user_id ) user_devices = user_devices["devices"] user_results = results.setdefault(user_id, {}) for device in user_devices: user_results[device["device_id"]] = device["keys"] user_ids_updated.append(user_id) except Exception as e: failures[destination] = _exception_to_failure(e) if len(destination_query) == len(user_ids_updated): # We've updated all the users in the query and we do not need to # make any further remote calls. return # Remove all the users from the query which we have updated for user_id in user_ids_updated: destination_query.pop(user_id) try: remote_result = yield self.federation.query_client_keys( destination, {"device_keys": destination_query}, timeout=timeout ) for user_id, keys in remote_result["device_keys"].items(): if user_id in destination_query: results[user_id] = keys if "master_keys" in remote_result: for user_id, key in remote_result["master_keys"].items(): if user_id in destination_query: cross_signing_keys["master_keys"][user_id] = key if "self_signing_keys" in remote_result: for user_id, key in remote_result["self_signing_keys"].items(): if user_id in destination_query: cross_signing_keys["self_signing_keys"][user_id] = key except Exception as e: failure = _exception_to_failure(e) failures[destination] = failure set_tag("error", True) set_tag("reason", failure) yield make_deferred_yieldable( defer.gatherResults( [ run_in_background(do_remote_query, destination) for destination in remote_queries_not_in_cache ], consumeErrors=True, ).addErrback(unwrapFirstError) ) ret = {"device_keys": results, "failures": failures} ret.update(cross_signing_keys) return ret @defer.inlineCallbacks def get_cross_signing_keys_from_cache(self, query, from_user_id): """Get cross-signing keys for users from the database Args: query (Iterable[string]) an iterable of user IDs. A dict whose keys are user IDs satisfies this, so the query format used for query_devices can be used here. from_user_id (str): the user making the query. This is used when adding cross-signing signatures to limit what signatures users can see. Returns: defer.Deferred[dict[str, dict[str, dict]]]: map from (master_keys|self_signing_keys|user_signing_keys) -> user_id -> key """ master_keys = {} self_signing_keys = {} user_signing_keys = {} user_ids = list(query) keys = yield self.store.get_e2e_cross_signing_keys_bulk(user_ids, from_user_id) for user_id, user_info in keys.items(): if user_info is None: continue if "master" in user_info: master_keys[user_id] = user_info["master"] if "self_signing" in user_info: self_signing_keys[user_id] = user_info["self_signing"] if ( from_user_id in keys and keys[from_user_id] is not None and "user_signing" in keys[from_user_id] ): # users can see other users' master and self-signing keys, but can # only see their own user-signing keys user_signing_keys[from_user_id] = keys[from_user_id]["user_signing"] return { "master_keys": master_keys, "self_signing_keys": self_signing_keys, "user_signing_keys": user_signing_keys, } @trace @defer.inlineCallbacks def query_local_devices(self, query): """Get E2E device keys for local users Args: query (dict[string, list[string]|None): map from user_id to a list of devices to query (None for all devices) Returns: defer.Deferred: (resolves to dict[string, dict[string, dict]]): map from user_id -> device_id -> device details """ set_tag("local_query", query) local_query = [] result_dict = {} for user_id, device_ids in query.items(): # we use UserID.from_string to catch invalid user ids if not self.is_mine(UserID.from_string(user_id)): logger.warning("Request for keys for non-local user %s", user_id) log_kv( { "message": "Requested a local key for a user which" " was not local to the homeserver", "user_id": user_id, } ) set_tag("error", True) raise SynapseError(400, "Not a user here") if not device_ids: local_query.append((user_id, None)) else: for device_id in device_ids: local_query.append((user_id, device_id)) # make sure that each queried user appears in the result dict result_dict[user_id] = {} results = yield self.store.get_e2e_device_keys(local_query) # Build the result structure for user_id, device_keys in results.items(): for device_id, device_info in device_keys.items(): result_dict[user_id][device_id] = device_info log_kv(results) return result_dict @defer.inlineCallbacks def on_federation_query_client_keys(self, query_body): """ Handle a device key query from a federated server """ device_keys_query = query_body.get("device_keys", {}) res = yield self.query_local_devices(device_keys_query) ret = {"device_keys": res} # add in the cross-signing keys cross_signing_keys = yield self.get_cross_signing_keys_from_cache( device_keys_query, None ) ret.update(cross_signing_keys) return ret @trace @defer.inlineCallbacks def claim_one_time_keys(self, query, timeout): local_query = [] remote_queries = {} for user_id, device_keys in query.get("one_time_keys", {}).items(): # we use UserID.from_string to catch invalid user ids if self.is_mine(UserID.from_string(user_id)): for device_id, algorithm in device_keys.items(): local_query.append((user_id, device_id, algorithm)) else: domain = get_domain_from_id(user_id) remote_queries.setdefault(domain, {})[user_id] = device_keys set_tag("local_key_query", local_query) set_tag("remote_key_query", remote_queries) results = yield self.store.claim_e2e_one_time_keys(local_query) json_result = {} failures = {} for user_id, device_keys in results.items(): for device_id, keys in device_keys.items(): for key_id, json_bytes in keys.items(): json_result.setdefault(user_id, {})[device_id] = { key_id: json.loads(json_bytes) } @trace @defer.inlineCallbacks def claim_client_keys(destination): set_tag("destination", destination) device_keys = remote_queries[destination] try: remote_result = yield self.federation.claim_client_keys( destination, {"one_time_keys": device_keys}, timeout=timeout ) for user_id, keys in remote_result["one_time_keys"].items(): if user_id in device_keys: json_result[user_id] = keys except Exception as e: failure = _exception_to_failure(e) failures[destination] = failure set_tag("error", True) set_tag("reason", failure) yield make_deferred_yieldable( defer.gatherResults( [ run_in_background(claim_client_keys, destination) for destination in remote_queries ], consumeErrors=True, ) ) logger.info( "Claimed one-time-keys: %s", ",".join( ( "%s for %s:%s" % (key_id, user_id, device_id) for user_id, user_keys in iteritems(json_result) for device_id, device_keys in iteritems(user_keys) for key_id, _ in iteritems(device_keys) ) ), ) log_kv({"one_time_keys": json_result, "failures": failures}) return {"one_time_keys": json_result, "failures": failures} @defer.inlineCallbacks @tag_args def upload_keys_for_user(self, user_id, device_id, keys): time_now = self.clock.time_msec() # TODO: Validate the JSON to make sure it has the right keys. device_keys = keys.get("device_keys", None) if device_keys: logger.info( "Updating device_keys for device %r for user %s at %d", device_id, user_id, time_now, ) log_kv( { "message": "Updating device_keys for user.", "user_id": user_id, "device_id": device_id, } ) # TODO: Sign the JSON with the server key changed = yield self.store.set_e2e_device_keys( user_id, device_id, time_now, device_keys ) if changed: # Only notify about device updates *if* the keys actually changed yield self.device_handler.notify_device_update(user_id, [device_id]) else: log_kv({"message": "Not updating device_keys for user", "user_id": user_id}) one_time_keys = keys.get("one_time_keys", None) if one_time_keys: log_kv( { "message": "Updating one_time_keys for device.", "user_id": user_id, "device_id": device_id, } ) yield self._upload_one_time_keys_for_user( user_id, device_id, time_now, one_time_keys ) else: log_kv( {"message": "Did not update one_time_keys", "reason": "no keys given"} ) # the device should have been registered already, but it may have been # deleted due to a race with a DELETE request. Or we may be using an # old access_token without an associated device_id. Either way, we # need to double-check the device is registered to avoid ending up with # keys without a corresponding device. yield self.device_handler.check_device_registered(user_id, device_id) result = yield self.store.count_e2e_one_time_keys(user_id, device_id) set_tag("one_time_key_counts", result) return {"one_time_key_counts": result} @defer.inlineCallbacks def _upload_one_time_keys_for_user( self, user_id, device_id, time_now, one_time_keys ): logger.info( "Adding one_time_keys %r for device %r for user %r at %d", one_time_keys.keys(), device_id, user_id, time_now, ) # make a list of (alg, id, key) tuples key_list = [] for key_id, key_obj in one_time_keys.items(): algorithm, key_id = key_id.split(":") key_list.append((algorithm, key_id, key_obj)) # First we check if we have already persisted any of the keys. existing_key_map = yield self.store.get_e2e_one_time_keys( user_id, device_id, [k_id for _, k_id, _ in key_list] ) new_keys = [] # Keys that we need to insert. (alg, id, json) tuples. for algorithm, key_id, key in key_list: ex_json = existing_key_map.get((algorithm, key_id), None) if ex_json: if not _one_time_keys_match(ex_json, key): raise SynapseError( 400, ( "One time key %s:%s already exists. " "Old key: %s; new key: %r" ) % (algorithm, key_id, ex_json, key), ) else: new_keys.append( (algorithm, key_id, encode_canonical_json(key).decode("ascii")) ) log_kv({"message": "Inserting new one_time_keys.", "keys": new_keys}) yield self.store.add_e2e_one_time_keys(user_id, device_id, time_now, new_keys) @defer.inlineCallbacks def upload_signing_keys_for_user(self, user_id, keys): """Upload signing keys for cross-signing Args: user_id (string): the user uploading the keys keys (dict[string, dict]): the signing keys """ # if a master key is uploaded, then check it. Otherwise, load the # stored master key, to check signatures on other keys if "master_key" in keys: master_key = keys["master_key"] _check_cross_signing_key(master_key, user_id, "master") else: master_key = yield self.store.get_e2e_cross_signing_key(user_id, "master") # if there is no master key, then we can't do anything, because all the # other cross-signing keys need to be signed by the master key if not master_key: raise SynapseError(400, "No master key available", Codes.MISSING_PARAM) try: master_key_id, master_verify_key = get_verify_key_from_cross_signing_key( master_key ) except ValueError: if "master_key" in keys: # the invalid key came from the request raise SynapseError(400, "Invalid master key", Codes.INVALID_PARAM) else: # the invalid key came from the database logger.error("Invalid master key found for user %s", user_id) raise SynapseError(500, "Invalid master key") # for the other cross-signing keys, make sure that they have valid # signatures from the master key if "self_signing_key" in keys: self_signing_key = keys["self_signing_key"] _check_cross_signing_key( self_signing_key, user_id, "self_signing", master_verify_key ) if "user_signing_key" in keys: user_signing_key = keys["user_signing_key"] _check_cross_signing_key( user_signing_key, user_id, "user_signing", master_verify_key ) # if everything checks out, then store the keys and send notifications deviceids = [] if "master_key" in keys: yield self.store.set_e2e_cross_signing_key(user_id, "master", master_key) deviceids.append(master_verify_key.version) if "self_signing_key" in keys: yield self.store.set_e2e_cross_signing_key( user_id, "self_signing", self_signing_key ) try: deviceids.append( get_verify_key_from_cross_signing_key(self_signing_key)[1].version ) except ValueError: raise SynapseError(400, "Invalid self-signing key", Codes.INVALID_PARAM) if "user_signing_key" in keys: yield self.store.set_e2e_cross_signing_key( user_id, "user_signing", user_signing_key ) # the signature stream matches the semantics that we want for # user-signing key updates: only the user themselves is notified of # their own user-signing key updates yield self.device_handler.notify_user_signature_update(user_id, [user_id]) # master key and self-signing key updates match the semantics of device # list updates: all users who share an encrypted room are notified if len(deviceids): yield self.device_handler.notify_device_update(user_id, deviceids) return {} @defer.inlineCallbacks def upload_signatures_for_device_keys(self, user_id, signatures): """Upload device signatures for cross-signing Args: user_id (string): the user uploading the signatures signatures (dict[string, dict[string, dict]]): map of users to devices to signed keys. This is the submission from the user; an exception will be raised if it is malformed. Returns: dict: response to be sent back to the client. The response will have a "failures" key, which will be a dict mapping users to devices to errors for the signatures that failed. Raises: SynapseError: if the signatures dict is not valid. """ failures = {} # signatures to be stored. Each item will be a SignatureListItem signature_list = [] # split between checking signatures for own user and signatures for # other users, since we verify them with different keys self_signatures = signatures.get(user_id, {}) other_signatures = {k: v for k, v in signatures.items() if k != user_id} self_signature_list, self_failures = yield self._process_self_signatures( user_id, self_signatures ) signature_list.extend(self_signature_list) failures.update(self_failures) other_signature_list, other_failures = yield self._process_other_signatures( user_id, other_signatures ) signature_list.extend(other_signature_list) failures.update(other_failures) # store the signature, and send the appropriate notifications for sync logger.debug("upload signature failures: %r", failures) yield self.store.store_e2e_cross_signing_signatures(user_id, signature_list) self_device_ids = [item.target_device_id for item in self_signature_list] if self_device_ids: yield self.device_handler.notify_device_update(user_id, self_device_ids) signed_users = [item.target_user_id for item in other_signature_list] if signed_users: yield self.device_handler.notify_user_signature_update( user_id, signed_users ) return {"failures": failures} @defer.inlineCallbacks def _process_self_signatures(self, user_id, signatures): """Process uploaded signatures of the user's own keys. Signatures of the user's own keys from this API come in two forms: - signatures of the user's devices by the user's self-signing key, - signatures of the user's master key by the user's devices. Args: user_id (string): the user uploading the keys signatures (dict[string, dict]): map of devices to signed keys Returns: (list[SignatureListItem], dict[string, dict[string, dict]]): a list of signatures to store, and a map of users to devices to failure reasons Raises: SynapseError: if the input is malformed """ signature_list = [] failures = {} if not signatures: return signature_list, failures if not isinstance(signatures, dict): raise SynapseError(400, "Invalid parameter", Codes.INVALID_PARAM) try: # get our self-signing key to verify the signatures ( _, self_signing_key_id, self_signing_verify_key, ) = yield self._get_e2e_cross_signing_verify_key(user_id, "self_signing") # get our master key, since we may have received a signature of it. # We need to fetch it here so that we know what its key ID is, so # that we can check if a signature that was sent is a signature of # the master key or of a device ( master_key, _, master_verify_key, ) = yield self._get_e2e_cross_signing_verify_key(user_id, "master") # fetch our stored devices. This is used to 1. verify # signatures on the master key, and 2. to compare with what # was sent if the device was signed devices = yield self.store.get_e2e_device_keys([(user_id, None)]) if user_id not in devices: raise NotFoundError("No device keys found") devices = devices[user_id] except SynapseError as e: failure = _exception_to_failure(e) failures[user_id] = {device: failure for device in signatures.keys()} return signature_list, failures for device_id, device in signatures.items(): # make sure submitted data is in the right form if not isinstance(device, dict): raise SynapseError(400, "Invalid parameter", Codes.INVALID_PARAM) try: if "signatures" not in device or user_id not in device["signatures"]: # no signature was sent raise SynapseError( 400, "Invalid signature", Codes.INVALID_SIGNATURE ) if device_id == master_verify_key.version: # The signature is of the master key. This needs to be # handled differently from signatures of normal devices. master_key_signature_list = self._check_master_key_signature( user_id, device_id, device, master_key, devices ) signature_list.extend(master_key_signature_list) continue # at this point, we have a device that should be signed # by the self-signing key if self_signing_key_id not in device["signatures"][user_id]: # no signature was sent raise SynapseError( 400, "Invalid signature", Codes.INVALID_SIGNATURE ) try: stored_device = devices[device_id] except KeyError: raise NotFoundError("Unknown device") if self_signing_key_id in stored_device.get("signatures", {}).get( user_id, {} ): # we already have a signature on this device, so we # can skip it, since it should be exactly the same continue _check_device_signature( user_id, self_signing_verify_key, device, stored_device ) signature = device["signatures"][user_id][self_signing_key_id] signature_list.append( SignatureListItem( self_signing_key_id, user_id, device_id, signature ) ) except SynapseError as e: failures.setdefault(user_id, {})[device_id] = _exception_to_failure(e) return signature_list, failures def _check_master_key_signature( self, user_id, master_key_id, signed_master_key, stored_master_key, devices ): """Check signatures of a user's master key made by their devices. Args: user_id (string): the user whose master key is being checked master_key_id (string): the ID of the user's master key signed_master_key (dict): the user's signed master key that was uploaded stored_master_key (dict): our previously-stored copy of the user's master key devices (iterable(dict)): the user's devices Returns: list[SignatureListItem]: a list of signatures to store Raises: SynapseError: if a signature is invalid """ # for each device that signed the master key, check the signature. master_key_signature_list = [] sigs = signed_master_key["signatures"] for signing_key_id, signature in sigs[user_id].items(): _, signing_device_id = signing_key_id.split(":", 1) if ( signing_device_id not in devices or signing_key_id not in devices[signing_device_id]["keys"] ): # signed by an unknown device, or the # device does not have the key raise SynapseError(400, "Invalid signature", Codes.INVALID_SIGNATURE) # get the key and check the signature pubkey = devices[signing_device_id]["keys"][signing_key_id] verify_key = decode_verify_key_bytes(signing_key_id, decode_base64(pubkey)) _check_device_signature( user_id, verify_key, signed_master_key, stored_master_key ) master_key_signature_list.append( SignatureListItem(signing_key_id, user_id, master_key_id, signature) ) return master_key_signature_list @defer.inlineCallbacks def _process_other_signatures(self, user_id, signatures): """Process uploaded signatures of other users' keys. These will be the target user's master keys, signed by the uploading user's user-signing key. Args: user_id (string): the user uploading the keys signatures (dict[string, dict]): map of users to devices to signed keys Returns: (list[SignatureListItem], dict[string, dict[string, dict]]): a list of signatures to store, and a map of users to devices to failure reasons Raises: SynapseError: if the input is malformed """ signature_list = [] failures = {} if not signatures: return signature_list, failures try: # get our user-signing key to verify the signatures ( user_signing_key, user_signing_key_id, user_signing_verify_key, ) = yield self._get_e2e_cross_signing_verify_key(user_id, "user_signing") except SynapseError as e: failure = _exception_to_failure(e) for user, devicemap in signatures.items(): failures[user] = {device_id: failure for device_id in devicemap.keys()} return signature_list, failures for target_user, devicemap in signatures.items(): # make sure submitted data is in the right form if not isinstance(devicemap, dict): raise SynapseError(400, "Invalid parameter", Codes.INVALID_PARAM) for device in devicemap.values(): if not isinstance(device, dict): raise SynapseError(400, "Invalid parameter", Codes.INVALID_PARAM) device_id = None try: # get the target user's master key, to make sure it matches # what was sent ( master_key, master_key_id, _, ) = yield self._get_e2e_cross_signing_verify_key( target_user, "master", user_id ) # make sure that the target user's master key is the one that # was signed (and no others) device_id = master_key_id.split(":", 1)[1] if device_id not in devicemap: logger.debug( "upload signature: could not find signature for device %s", device_id, ) # set device to None so that the failure gets # marked on all the signatures device_id = None raise NotFoundError("Unknown device") key = devicemap[device_id] other_devices = [k for k in devicemap.keys() if k != device_id] if other_devices: # other devices were signed -- mark those as failures logger.debug("upload signature: too many devices specified") failure = _exception_to_failure(NotFoundError("Unknown device")) failures[target_user] = { device: failure for device in other_devices } if user_signing_key_id in master_key.get("signatures", {}).get( user_id, {} ): # we already have the signature, so we can skip it continue _check_device_signature( user_id, user_signing_verify_key, key, master_key ) signature = key["signatures"][user_id][user_signing_key_id] signature_list.append( SignatureListItem( user_signing_key_id, target_user, device_id, signature ) ) except SynapseError as e: failure = _exception_to_failure(e) if device_id is None: failures[target_user] = { device_id: failure for device_id in devicemap.keys() } else: failures.setdefault(target_user, {})[device_id] = failure return signature_list, failures @defer.inlineCallbacks def _get_e2e_cross_signing_verify_key( self, user_id, desired_key_type, from_user_id=None ): """Fetch the cross-signing public key from storage and interpret it. If we cannot find the public key locally, we query the keys from the homeserver they belong to, then update our local copy. Args: user_id (str): the user whose key should be fetched desired_key_type (str): the type of key to fetch from_user_id (str): the user that we are fetching the keys for. This affects what signatures are fetched. Returns: dict, str, VerifyKey: the raw key data, the key ID, and the signedjson verify key Raises: NotFoundError: if the key is not found """ user = UserID.from_string(user_id) key = yield self.store.get_e2e_cross_signing_key( user_id, desired_key_type, from_user_id ) # If we still can't find the key, and we're looking for keys of another user, # then attempt to fetch the missing key from the remote user's server. if ( key is None and not self.is_mine(user) # We don't get "user_signing" keys from remote servers, so disallow that here and desired_key_type != "user_signing" ): try: remote_result = yield self.federation.query_user_devices( user.domain, user_id ) # Process each of the retrieved cross-signing keys for key_type in ["master", "self_signing"]: key_content = remote_result.get(key_type + "_key") if not key_content: continue # If this is the desired key type, return it if key_type == desired_key_type: key = key_content # At the same time, store this key in the db for # subsequent queries yield self.store.set_e2e_cross_signing_key( user_id, key_type, key_content ) except Exception as e: logger.warning( "Unable to query %s for cross-signing keys of user %s: %s", user.domain, user_id, e, ) 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 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 checking, and ensures that it is signed, if a signature is required. Args: key (dict): the key data to verify user_id (str): the user whose key is being checked key_type (str): the type of key that the key should be signing_key (VerifyKey): (optional) the signing key that the key should be signed with. If omitted, signatures will not be checked. """ if ( key.get("user_id") != user_id or key_type not in key.get("usage", []) or len(key.get("keys", {})) != 1 ): raise SynapseError(400, ("Invalid %s key" % (key_type,)), Codes.INVALID_PARAM) if signing_key: try: verify_signed_json(key, user_id, signing_key) except SignatureVerifyException: raise SynapseError( 400, ("Invalid signature on %s key" % key_type), Codes.INVALID_SIGNATURE ) def _check_device_signature(user_id, verify_key, signed_device, stored_device): """Check that a signature on a device or cross-signing key is correct and matches the copy of the device/key that we have stored. Throws an exception if an error is detected. Args: user_id (str): the user ID whose signature is being checked verify_key (VerifyKey): the key to verify the device with signed_device (dict): the uploaded signed device data stored_device (dict): our previously stored copy of the device Raises: SynapseError: if the signature was invalid or the sent device is not the same as the stored device """ # make sure that the device submitted matches what we have stored stripped_signed_device = { k: v for k, v in signed_device.items() if k not in ["signatures", "unsigned"] } stripped_stored_device = { k: v for k, v in stored_device.items() if k not in ["signatures", "unsigned"] } if stripped_signed_device != stripped_stored_device: logger.debug( "upload signatures: key does not match %s vs %s", signed_device, stored_device, ) raise SynapseError(400, "Key does not match") try: verify_signed_json(signed_device, user_id, verify_key) except SignatureVerifyException: logger.debug("invalid signature on key") raise SynapseError(400, "Invalid signature", Codes.INVALID_SIGNATURE) def _exception_to_failure(e): if isinstance(e, SynapseError): return {"status": e.code, "errcode": e.errcode, "message": str(e)} if isinstance(e, CodeMessageException): return {"status": e.code, "message": str(e)} if isinstance(e, NotRetryingDestination): return {"status": 503, "message": "Not ready for retry"} # include ConnectionRefused and other errors # # Note that some Exceptions (notably twisted's ResponseFailed etc) don't # give a string for e.message, which json then fails to serialize. return {"status": 503, "message": str(e)} def _one_time_keys_match(old_key_json, new_key): old_key = json.loads(old_key_json) # if either is a string rather than an object, they must match exactly if not isinstance(old_key, dict) or not isinstance(new_key, dict): return old_key == new_key # otherwise, we strip off the 'signatures' if any, because it's legitimate # for different upload attempts to have different signatures. old_key.pop("signatures", None) new_key_copy = dict(new_key) new_key_copy.pop("signatures", None) return old_key == new_key_copy @attr.s class SignatureListItem: """An item in the signature list as used by upload_signatures_for_device_keys. """ signing_key_id = attr.ib() target_user_id = attr.ib() target_device_id = attr.ib() signature = attr.ib() class SigningKeyEduUpdater(object): """Handles incoming signing key updates from federation and updates the DB""" def __init__(self, hs, e2e_keys_handler): self.store = hs.get_datastore() self.federation = hs.get_federation_client() self.clock = hs.get_clock() self.e2e_keys_handler = e2e_keys_handler self._remote_edu_linearizer = Linearizer(name="remote_signing_key") # user_id -> list of updates waiting to be handled. self._pending_updates = {} # Recently seen stream ids. We don't bother keeping these in the DB, # but they're useful to have them about to reduce the number of spurious # resyncs. self._seen_updates = ExpiringCache( cache_name="signing_key_update_edu", clock=self.clock, max_len=10000, expiry_ms=30 * 60 * 1000, iterable=True, ) @defer.inlineCallbacks def incoming_signing_key_update(self, origin, edu_content): """Called on incoming signing key update from federation. Responsible for parsing the EDU and adding to pending updates list. Args: origin (string): the server that sent the EDU edu_content (dict): the contents of the EDU """ user_id = edu_content.pop("user_id") master_key = edu_content.pop("master_key", None) self_signing_key = edu_content.pop("self_signing_key", None) if get_domain_from_id(user_id) != origin: logger.warning("Got signing key update edu for %r from %r", user_id, origin) return room_ids = yield self.store.get_rooms_for_user(user_id) if not room_ids: # We don't share any rooms with this user. Ignore update, as we # probably won't get any further updates. return self._pending_updates.setdefault(user_id, []).append( (master_key, self_signing_key) ) yield self._handle_signing_key_updates(user_id) @defer.inlineCallbacks def _handle_signing_key_updates(self, user_id): """Actually handle pending updates. Args: user_id (string): the user whose updates we are processing """ device_handler = self.e2e_keys_handler.device_handler with (yield self._remote_edu_linearizer.queue(user_id)): pending_updates = self._pending_updates.pop(user_id, []) if not pending_updates: # This can happen since we batch updates return device_ids = [] logger.info("pending updates: %r", pending_updates) for master_key, self_signing_key in pending_updates: if master_key: yield self.store.set_e2e_cross_signing_key( user_id, "master", master_key ) _, verify_key = get_verify_key_from_cross_signing_key(master_key) # 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 device_ids.append(verify_key.version) if self_signing_key: yield self.store.set_e2e_cross_signing_key( user_id, "self_signing", self_signing_key ) _, verify_key = get_verify_key_from_cross_signing_key( self_signing_key ) device_ids.append(verify_key.version) yield device_handler.notify_device_update(user_id, device_ids)