diff options
Diffstat (limited to 'synapse/handlers/e2e_keys.py')
| -rw-r--r-- | synapse/handlers/e2e_keys.py | 882 |
1 files changed, 858 insertions, 24 deletions
diff --git a/synapse/handlers/e2e_keys.py b/synapse/handlers/e2e_keys.py index 056fb97acb..774a252619 100644 --- a/synapse/handlers/e2e_keys.py +++ b/synapse/handlers/e2e_keys.py @@ -1,6 +1,7 @@ # -*- coding: utf-8 -*- # Copyright 2016 OpenMarket Ltd -# Copyright 2018 New Vector 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. @@ -18,15 +19,26 @@ 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, SynapseError +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.types import UserID, get_domain_from_id +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__) @@ -40,16 +52,35 @@ class E2eKeysHandler(object): 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. - hs.get_federation_registry().register_query_handler( + federation_registry.register_query_handler( "client_keys", self.on_federation_query_client_keys ) @trace @defer.inlineCallbacks - def query_devices(self, query_body, timeout): + def query_devices(self, query_body, timeout, from_user_id): """ Handle a device key query from a client { @@ -67,6 +98,11 @@ class E2eKeysHandler(object): } } } + + 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", {}) @@ -105,9 +141,10 @@ class E2eKeysHandler(object): else: query_list.append((user_id, None)) - user_ids_not_in_cache, remote_results = ( - yield self.store.get_user_devices_from_cache(query_list) - ) + ( + 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): @@ -125,6 +162,11 @@ class E2eKeysHandler(object): 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 @@ -132,8 +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] @@ -160,12 +202,19 @@ class E2eKeysHandler(object): # 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 - ) + 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: - results[user_id] = {device["device_id"]: device["keys"]} + user_results[device["device_id"]] = device["keys"] user_ids_updated.append(user_id) except Exception as e: failures[destination] = _exception_to_failure(e) @@ -188,6 +237,16 @@ class E2eKeysHandler(object): 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 @@ -204,7 +263,58 @@ class E2eKeysHandler(object): ).addErrback(unwrapFirstError) ) - return {"device_keys": results, "failures": failures} + 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 @@ -248,16 +358,10 @@ class E2eKeysHandler(object): results = yield self.store.get_e2e_device_keys(local_query) - # Build the result structure, un-jsonify the results, and add the - # "unsigned" section + # Build the result structure 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 + result_dict[user_id][device_id] = device_info log_kv(results) return result_dict @@ -268,7 +372,16 @@ class E2eKeysHandler(object): """ device_keys_query = query_body.get("device_keys", {}) res = yield self.query_local_devices(device_keys_query) - return {"device_keys": res} + 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 @@ -447,8 +560,633 @@ class E2eKeysHandler(object): 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: 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: 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: + dict, str, VerifyKey: the raw key data, the key ID, and the + signedjson verify key + + 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: + raise NotFoundError("No %s key found for %s" % (key_type, user_id)) + + 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 + 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)} @@ -476,3 +1214,99 @@ def _one_time_keys_match(old_key_json, 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 + device_list_updater = device_handler.device_list_updater + + 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: + new_device_ids = yield device_list_updater.process_cross_signing_key_update( + user_id, master_key, self_signing_key, + ) + device_ids = device_ids + new_device_ids + + yield device_handler.notify_device_update(user_id, device_ids) |