# -*- 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 from canonicaljson import encode_canonical_json, json from signedjson.sign import SignatureVerifyException, verify_signed_json from twisted.internet import defer from synapse.api.errors import CodeMessageException, Codes, SynapseError from synapse.logging.context import make_deferred_yieldable, run_in_background from synapse.types import ( UserID, get_domain_from_id, get_verify_key_from_cross_signing_key, ) from synapse.util import unwrapFirstError 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() # 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. hs.get_federation_registry().register_query_handler( "client_keys", self.on_federation_query_client_keys ) @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 # 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 @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: user_devices = yield self.device_handler.device_list_updater.user_device_resync( user_id ) user_devices = user_devices["devices"] for device in user_devices: results[user_id] = {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 for user_id, key in remote_result["master_keys"].items(): if user_id in destination_query: cross_signing_keys["master_keys"][user_id] = key 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 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|self_signing|user_signing) -> user_id -> key """ master_keys = {} self_signing_keys = {} user_signing_keys = {} for user_id in query: # XXX: consider changing the store functions to allow querying # multiple users simultaneously. key = yield self.store.get_e2e_cross_signing_key( user_id, "master", from_user_id ) if key: master_keys[user_id] = key key = yield self.store.get_e2e_cross_signing_key( user_id, "self_signing", from_user_id ) if key: self_signing_keys[user_id] = key # users can see other users' master and self-signing keys, but can # only see their own user-signing keys if from_user_id == user_id: key = yield self.store.get_e2e_cross_signing_key( user_id, "user_signing", from_user_id ) if key: user_signing_keys[user_id] = key return { "master_keys": master_keys, "self_signing_keys": self_signing_keys, "user_signing_keys": user_signing_keys, } @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 """ 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) 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, un-jsonify the results, and add the # "unsigned" section for user_id, device_keys in results.items(): for device_id, device_info in device_keys.items(): r = dict(device_info["keys"]) r["unsigned"] = {} display_name = device_info["device_display_name"] if display_name is not None: r["unsigned"]["device_display_name"] = display_name result_dict[user_id][device_id] = r 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) return {"device_keys": res} @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 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) } @defer.inlineCallbacks def claim_client_keys(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 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) ) ), ) return {"one_time_keys": json_result, "failures": failures} @defer.inlineCallbacks 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, ) # 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]) one_time_keys = keys.get("one_time_keys", None) if one_time_keys: yield self._upload_one_time_keys_for_user( user_id, device_id, time_now, one_time_keys ) # 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) 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")) ) 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 {} 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 _exception_to_failure(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