685 lines
24 KiB
Python
685 lines
24 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2014, 2015 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from synapse.crypto.keyclient import fetch_server_key
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from synapse.api.errors import SynapseError, Codes
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from synapse.util.retryutils import get_retry_limiter
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from synapse.util import unwrapFirstError
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from synapse.util.async import ObservableDeferred
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from twisted.internet import defer
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from signedjson.sign import (
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verify_signed_json, signature_ids, sign_json, encode_canonical_json
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)
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from signedjson.key import (
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is_signing_algorithm_supported, decode_verify_key_bytes
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)
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from unpaddedbase64 import decode_base64, encode_base64
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from OpenSSL import crypto
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from collections import namedtuple
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import urllib
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import hashlib
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import logging
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logger = logging.getLogger(__name__)
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KeyGroup = namedtuple("KeyGroup", ("server_name", "group_id", "key_ids"))
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class Keyring(object):
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def __init__(self, hs):
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self.store = hs.get_datastore()
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self.clock = hs.get_clock()
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self.client = hs.get_http_client()
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self.config = hs.get_config()
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self.perspective_servers = self.config.perspectives
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self.hs = hs
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self.key_downloads = {}
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def verify_json_for_server(self, server_name, json_object):
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return self.verify_json_objects_for_server(
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[(server_name, json_object)]
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)[0]
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def verify_json_objects_for_server(self, server_and_json):
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"""Bulk verfies signatures of json objects, bulk fetching keys as
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necessary.
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Args:
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server_and_json (list): List of pairs of (server_name, json_object)
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Returns:
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list of deferreds indicating success or failure to verify each
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json object's signature for the given server_name.
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"""
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group_id_to_json = {}
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group_id_to_group = {}
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group_ids = []
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next_group_id = 0
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deferreds = {}
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for server_name, json_object in server_and_json:
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logger.debug("Verifying for %s", server_name)
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group_id = next_group_id
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next_group_id += 1
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group_ids.append(group_id)
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key_ids = signature_ids(json_object, server_name)
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if not key_ids:
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deferreds[group_id] = defer.fail(SynapseError(
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400,
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"Not signed with a supported algorithm",
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Codes.UNAUTHORIZED,
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))
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else:
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deferreds[group_id] = defer.Deferred()
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group = KeyGroup(server_name, group_id, key_ids)
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group_id_to_group[group_id] = group
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group_id_to_json[group_id] = json_object
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@defer.inlineCallbacks
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def handle_key_deferred(group, deferred):
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server_name = group.server_name
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try:
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_, _, key_id, verify_key = yield deferred
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except IOError as e:
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logger.warn(
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"Got IOError when downloading keys for %s: %s %s",
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server_name, type(e).__name__, str(e.message),
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)
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raise SynapseError(
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502,
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"Error downloading keys for %s" % (server_name,),
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Codes.UNAUTHORIZED,
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)
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except Exception as e:
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logger.exception(
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"Got Exception when downloading keys for %s: %s %s",
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server_name, type(e).__name__, str(e.message),
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)
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raise SynapseError(
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401,
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"No key for %s with id %s" % (server_name, key_ids),
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Codes.UNAUTHORIZED,
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)
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json_object = group_id_to_json[group.group_id]
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try:
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verify_signed_json(json_object, server_name, verify_key)
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except:
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raise SynapseError(
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401,
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"Invalid signature for server %s with key %s:%s" % (
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server_name, verify_key.alg, verify_key.version
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),
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Codes.UNAUTHORIZED,
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)
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server_to_deferred = {
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server_name: defer.Deferred()
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for server_name, _ in server_and_json
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}
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# We want to wait for any previous lookups to complete before
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# proceeding.
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wait_on_deferred = self.wait_for_previous_lookups(
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[server_name for server_name, _ in server_and_json],
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server_to_deferred,
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)
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# Actually start fetching keys.
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wait_on_deferred.addBoth(
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lambda _: self.get_server_verify_keys(group_id_to_group, deferreds)
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)
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# When we've finished fetching all the keys for a given server_name,
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# resolve the deferred passed to `wait_for_previous_lookups` so that
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# any lookups waiting will proceed.
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server_to_gids = {}
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def remove_deferreds(res, server_name, group_id):
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server_to_gids[server_name].discard(group_id)
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if not server_to_gids[server_name]:
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d = server_to_deferred.pop(server_name, None)
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if d:
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d.callback(None)
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return res
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for g_id, deferred in deferreds.items():
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server_name = group_id_to_group[g_id].server_name
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server_to_gids.setdefault(server_name, set()).add(g_id)
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deferred.addBoth(remove_deferreds, server_name, g_id)
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# Pass those keys to handle_key_deferred so that the json object
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# signatures can be verified
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return [
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handle_key_deferred(
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group_id_to_group[g_id],
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deferreds[g_id],
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)
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for g_id in group_ids
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]
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@defer.inlineCallbacks
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def wait_for_previous_lookups(self, server_names, server_to_deferred):
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"""Waits for any previous key lookups for the given servers to finish.
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Args:
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server_names (list): list of server_names we want to lookup
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server_to_deferred (dict): server_name to deferred which gets
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resolved once we've finished looking up keys for that server
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"""
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while True:
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wait_on = [
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self.key_downloads[server_name]
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for server_name in server_names
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if server_name in self.key_downloads
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]
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if wait_on:
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yield defer.DeferredList(wait_on)
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else:
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break
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for server_name, deferred in server_to_deferred.items():
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d = ObservableDeferred(deferred)
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self.key_downloads[server_name] = d
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def rm(r, server_name):
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self.key_downloads.pop(server_name, None)
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return r
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d.addBoth(rm, server_name)
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def get_server_verify_keys(self, group_id_to_group, group_id_to_deferred):
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"""Takes a dict of KeyGroups and tries to find at least one key for
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each group.
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"""
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# These are functions that produce keys given a list of key ids
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key_fetch_fns = (
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self.get_keys_from_store, # First try the local store
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self.get_keys_from_perspectives, # Then try via perspectives
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self.get_keys_from_server, # Then try directly
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)
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@defer.inlineCallbacks
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def do_iterations():
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merged_results = {}
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missing_keys = {}
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for group in group_id_to_group.values():
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missing_keys.setdefault(group.server_name, set()).update(
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group.key_ids
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)
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for fn in key_fetch_fns:
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results = yield fn(missing_keys.items())
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merged_results.update(results)
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# We now need to figure out which groups we have keys for
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# and which we don't
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missing_groups = {}
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for group in group_id_to_group.values():
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for key_id in group.key_ids:
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if key_id in merged_results[group.server_name]:
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group_id_to_deferred[group.group_id].callback((
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group.group_id,
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group.server_name,
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key_id,
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merged_results[group.server_name][key_id],
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))
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break
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else:
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missing_groups.setdefault(
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group.server_name, []
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).append(group)
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if not missing_groups:
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break
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missing_keys = {
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server_name: set(
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key_id for group in groups for key_id in group.key_ids
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)
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for server_name, groups in missing_groups.items()
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}
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for group in missing_groups.values():
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group_id_to_deferred[group.group_id].errback(SynapseError(
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401,
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"No key for %s with id %s" % (
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group.server_name, group.key_ids,
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),
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Codes.UNAUTHORIZED,
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))
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def on_err(err):
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for deferred in group_id_to_deferred.values():
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if not deferred.called:
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deferred.errback(err)
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do_iterations().addErrback(on_err)
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return group_id_to_deferred
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@defer.inlineCallbacks
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def get_keys_from_store(self, server_name_and_key_ids):
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res = yield defer.gatherResults(
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[
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self.store.get_server_verify_keys(
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server_name, key_ids
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).addCallback(lambda ks, server: (server, ks), server_name)
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for server_name, key_ids in server_name_and_key_ids
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],
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consumeErrors=True,
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).addErrback(unwrapFirstError)
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defer.returnValue(dict(res))
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@defer.inlineCallbacks
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def get_keys_from_perspectives(self, server_name_and_key_ids):
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@defer.inlineCallbacks
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def get_key(perspective_name, perspective_keys):
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try:
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result = yield self.get_server_verify_key_v2_indirect(
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server_name_and_key_ids, perspective_name, perspective_keys
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)
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defer.returnValue(result)
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except Exception as e:
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logger.exception(
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"Unable to get key from %r: %s %s",
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perspective_name,
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type(e).__name__, str(e.message),
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)
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defer.returnValue({})
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results = yield defer.gatherResults(
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[
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get_key(p_name, p_keys)
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for p_name, p_keys in self.perspective_servers.items()
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],
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consumeErrors=True,
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).addErrback(unwrapFirstError)
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union_of_keys = {}
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for result in results:
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for server_name, keys in result.items():
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union_of_keys.setdefault(server_name, {}).update(keys)
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defer.returnValue(union_of_keys)
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@defer.inlineCallbacks
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def get_keys_from_server(self, server_name_and_key_ids):
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@defer.inlineCallbacks
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def get_key(server_name, key_ids):
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limiter = yield get_retry_limiter(
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server_name,
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self.clock,
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self.store,
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)
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with limiter:
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keys = None
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try:
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keys = yield self.get_server_verify_key_v2_direct(
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server_name, key_ids
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)
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except Exception as e:
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logger.info(
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"Unable to getting key %r for %r directly: %s %s",
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key_ids, server_name,
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type(e).__name__, str(e.message),
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)
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if not keys:
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keys = yield self.get_server_verify_key_v1_direct(
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server_name, key_ids
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)
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keys = {server_name: keys}
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defer.returnValue(keys)
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results = yield defer.gatherResults(
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[
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get_key(server_name, key_ids)
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for server_name, key_ids in server_name_and_key_ids
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],
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consumeErrors=True,
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).addErrback(unwrapFirstError)
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merged = {}
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for result in results:
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merged.update(result)
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defer.returnValue({
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server_name: keys
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for server_name, keys in merged.items()
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if keys
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})
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@defer.inlineCallbacks
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def get_server_verify_key_v2_indirect(self, server_names_and_key_ids,
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perspective_name,
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perspective_keys):
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# TODO(mark): Set the minimum_valid_until_ts to that needed by
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# the events being validated or the current time if validating
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# an incoming request.
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query_response = yield self.client.post_json(
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destination=perspective_name,
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path=b"/_matrix/key/v2/query",
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data={
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u"server_keys": {
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server_name: {
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key_id: {
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u"minimum_valid_until_ts": 0
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} for key_id in key_ids
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}
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for server_name, key_ids in server_names_and_key_ids
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}
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},
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long_retries=True,
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)
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keys = {}
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responses = query_response["server_keys"]
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for response in responses:
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if (u"signatures" not in response
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or perspective_name not in response[u"signatures"]):
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raise ValueError(
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"Key response not signed by perspective server"
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" %r" % (perspective_name,)
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)
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verified = False
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for key_id in response[u"signatures"][perspective_name]:
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if key_id in perspective_keys:
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verify_signed_json(
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response,
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perspective_name,
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perspective_keys[key_id]
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)
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verified = True
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if not verified:
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logging.info(
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"Response from perspective server %r not signed with a"
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" known key, signed with: %r, known keys: %r",
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perspective_name,
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list(response[u"signatures"][perspective_name]),
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list(perspective_keys)
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)
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raise ValueError(
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"Response not signed with a known key for perspective"
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" server %r" % (perspective_name,)
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)
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processed_response = yield self.process_v2_response(
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perspective_name, response
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)
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for server_name, response_keys in processed_response.items():
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keys.setdefault(server_name, {}).update(response_keys)
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yield defer.gatherResults(
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[
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self.store_keys(
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server_name=server_name,
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from_server=perspective_name,
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verify_keys=response_keys,
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)
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for server_name, response_keys in keys.items()
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],
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consumeErrors=True
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).addErrback(unwrapFirstError)
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defer.returnValue(keys)
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@defer.inlineCallbacks
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def get_server_verify_key_v2_direct(self, server_name, key_ids):
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keys = {}
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for requested_key_id in key_ids:
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if requested_key_id in keys:
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continue
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(response, tls_certificate) = yield fetch_server_key(
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server_name, self.hs.tls_server_context_factory,
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path=(b"/_matrix/key/v2/server/%s" % (
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urllib.quote(requested_key_id),
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)).encode("ascii"),
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)
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if (u"signatures" not in response
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or server_name not in response[u"signatures"]):
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raise ValueError("Key response not signed by remote server")
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if "tls_fingerprints" not in response:
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raise ValueError("Key response missing TLS fingerprints")
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certificate_bytes = crypto.dump_certificate(
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crypto.FILETYPE_ASN1, tls_certificate
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)
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sha256_fingerprint = hashlib.sha256(certificate_bytes).digest()
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sha256_fingerprint_b64 = encode_base64(sha256_fingerprint)
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response_sha256_fingerprints = set()
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for fingerprint in response[u"tls_fingerprints"]:
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if u"sha256" in fingerprint:
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response_sha256_fingerprints.add(fingerprint[u"sha256"])
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if sha256_fingerprint_b64 not in response_sha256_fingerprints:
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raise ValueError("TLS certificate not allowed by fingerprints")
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response_keys = yield self.process_v2_response(
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from_server=server_name,
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requested_ids=[requested_key_id],
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response_json=response,
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)
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keys.update(response_keys)
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yield defer.gatherResults(
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[
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self.store_keys(
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server_name=key_server_name,
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from_server=server_name,
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verify_keys=verify_keys,
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)
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for key_server_name, verify_keys in keys.items()
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],
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consumeErrors=True
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).addErrback(unwrapFirstError)
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defer.returnValue(keys)
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@defer.inlineCallbacks
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def process_v2_response(self, from_server, response_json,
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requested_ids=[]):
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time_now_ms = self.clock.time_msec()
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response_keys = {}
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verify_keys = {}
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for key_id, key_data in response_json["verify_keys"].items():
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if is_signing_algorithm_supported(key_id):
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key_base64 = key_data["key"]
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key_bytes = decode_base64(key_base64)
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verify_key = decode_verify_key_bytes(key_id, key_bytes)
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verify_key.time_added = time_now_ms
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verify_keys[key_id] = verify_key
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old_verify_keys = {}
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for key_id, key_data in response_json["old_verify_keys"].items():
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if is_signing_algorithm_supported(key_id):
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key_base64 = key_data["key"]
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|
key_bytes = decode_base64(key_base64)
|
|
verify_key = decode_verify_key_bytes(key_id, key_bytes)
|
|
verify_key.expired = key_data["expired_ts"]
|
|
verify_key.time_added = time_now_ms
|
|
old_verify_keys[key_id] = verify_key
|
|
|
|
results = {}
|
|
server_name = response_json["server_name"]
|
|
for key_id in response_json["signatures"].get(server_name, {}):
|
|
if key_id not in response_json["verify_keys"]:
|
|
raise ValueError(
|
|
"Key response must include verification keys for all"
|
|
" signatures"
|
|
)
|
|
if key_id in verify_keys:
|
|
verify_signed_json(
|
|
response_json,
|
|
server_name,
|
|
verify_keys[key_id]
|
|
)
|
|
|
|
signed_key_json = sign_json(
|
|
response_json,
|
|
self.config.server_name,
|
|
self.config.signing_key[0],
|
|
)
|
|
|
|
signed_key_json_bytes = encode_canonical_json(signed_key_json)
|
|
ts_valid_until_ms = signed_key_json[u"valid_until_ts"]
|
|
|
|
updated_key_ids = set(requested_ids)
|
|
updated_key_ids.update(verify_keys)
|
|
updated_key_ids.update(old_verify_keys)
|
|
|
|
response_keys.update(verify_keys)
|
|
response_keys.update(old_verify_keys)
|
|
|
|
yield defer.gatherResults(
|
|
[
|
|
self.store.store_server_keys_json(
|
|
server_name=server_name,
|
|
key_id=key_id,
|
|
from_server=server_name,
|
|
ts_now_ms=time_now_ms,
|
|
ts_expires_ms=ts_valid_until_ms,
|
|
key_json_bytes=signed_key_json_bytes,
|
|
)
|
|
for key_id in updated_key_ids
|
|
],
|
|
consumeErrors=True,
|
|
).addErrback(unwrapFirstError)
|
|
|
|
results[server_name] = response_keys
|
|
|
|
defer.returnValue(results)
|
|
|
|
@defer.inlineCallbacks
|
|
def get_server_verify_key_v1_direct(self, server_name, key_ids):
|
|
"""Finds a verification key for the server with one of the key ids.
|
|
Args:
|
|
server_name (str): The name of the server to fetch a key for.
|
|
keys_ids (list of str): The key_ids to check for.
|
|
"""
|
|
|
|
# Try to fetch the key from the remote server.
|
|
|
|
(response, tls_certificate) = yield fetch_server_key(
|
|
server_name, self.hs.tls_server_context_factory
|
|
)
|
|
|
|
# Check the response.
|
|
|
|
x509_certificate_bytes = crypto.dump_certificate(
|
|
crypto.FILETYPE_ASN1, tls_certificate
|
|
)
|
|
|
|
if ("signatures" not in response
|
|
or server_name not in response["signatures"]):
|
|
raise ValueError("Key response not signed by remote server")
|
|
|
|
if "tls_certificate" not in response:
|
|
raise ValueError("Key response missing TLS certificate")
|
|
|
|
tls_certificate_b64 = response["tls_certificate"]
|
|
|
|
if encode_base64(x509_certificate_bytes) != tls_certificate_b64:
|
|
raise ValueError("TLS certificate doesn't match")
|
|
|
|
# Cache the result in the datastore.
|
|
|
|
time_now_ms = self.clock.time_msec()
|
|
|
|
verify_keys = {}
|
|
for key_id, key_base64 in response["verify_keys"].items():
|
|
if is_signing_algorithm_supported(key_id):
|
|
key_bytes = decode_base64(key_base64)
|
|
verify_key = decode_verify_key_bytes(key_id, key_bytes)
|
|
verify_key.time_added = time_now_ms
|
|
verify_keys[key_id] = verify_key
|
|
|
|
for key_id in response["signatures"][server_name]:
|
|
if key_id not in response["verify_keys"]:
|
|
raise ValueError(
|
|
"Key response must include verification keys for all"
|
|
" signatures"
|
|
)
|
|
if key_id in verify_keys:
|
|
verify_signed_json(
|
|
response,
|
|
server_name,
|
|
verify_keys[key_id]
|
|
)
|
|
|
|
yield self.store.store_server_certificate(
|
|
server_name,
|
|
server_name,
|
|
time_now_ms,
|
|
tls_certificate,
|
|
)
|
|
|
|
yield self.store_keys(
|
|
server_name=server_name,
|
|
from_server=server_name,
|
|
verify_keys=verify_keys,
|
|
)
|
|
|
|
defer.returnValue(verify_keys)
|
|
|
|
@defer.inlineCallbacks
|
|
def store_keys(self, server_name, from_server, verify_keys):
|
|
"""Store a collection of verify keys for a given server
|
|
Args:
|
|
server_name(str): The name of the server the keys are for.
|
|
from_server(str): The server the keys were downloaded from.
|
|
verify_keys(dict): A mapping of key_id to VerifyKey.
|
|
Returns:
|
|
A deferred that completes when the keys are stored.
|
|
"""
|
|
# TODO(markjh): Store whether the keys have expired.
|
|
yield defer.gatherResults(
|
|
[
|
|
self.store.store_server_verify_key(
|
|
server_name, server_name, key.time_added, key
|
|
)
|
|
for key_id, key in verify_keys.items()
|
|
],
|
|
consumeErrors=True,
|
|
).addErrback(unwrapFirstError)
|