diff options
Diffstat (limited to 'synapse/handlers/e2e_keys.py')
| -rw-r--r-- | synapse/handlers/e2e_keys.py | 198 |
1 files changed, 193 insertions, 5 deletions
diff --git a/synapse/handlers/e2e_keys.py b/synapse/handlers/e2e_keys.py index 0a84d0e2b0..be675197f1 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. @@ -19,13 +20,18 @@ 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, SynapseError +from synapse.api.errors import CodeMessageException, Codes, 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.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 @@ -49,7 +55,7 @@ class E2eKeysHandler(object): @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 +73,11 @@ 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", {}) @@ -125,6 +136,11 @@ 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 @@ -188,6 +204,14 @@ class E2eKeysHandler(object): 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 @@ -204,7 +228,61 @@ 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|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, + } @trace @defer.inlineCallbacks @@ -441,6 +519,116 @@ 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 {} + + +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): |