470 lines
16 KiB
Python
470 lines
16 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 twisted.internet import defer
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from syutil.crypto.jsonsign import (
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verify_signed_json, signature_ids, sign_json, encode_canonical_json
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)
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from syutil.crypto.signing_key import (
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is_signing_algorithm_supported, decode_verify_key_bytes
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)
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from syutil.base64util import decode_base64, encode_base64
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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.async import ObservableDeferred
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from OpenSSL import crypto
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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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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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@defer.inlineCallbacks
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def verify_json_for_server(self, server_name, json_object):
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logger.debug("Verifying for %s", server_name)
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key_ids = signature_ids(json_object, server_name)
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if not key_ids:
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raise 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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try:
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verify_key = yield self.get_server_verify_key(server_name, key_ids)
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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.warn(
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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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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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@defer.inlineCallbacks
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def get_server_verify_key(self, server_name, key_ids):
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"""Finds a verification key for the server with one of the key ids.
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Trys to fetch the key from a trusted perspective server first.
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Args:
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server_name(str): The name of the server to fetch a key for.
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keys_ids (list of str): The key_ids to check for.
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"""
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cached = yield self.store.get_server_verify_keys(server_name, key_ids)
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if cached:
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defer.returnValue(cached[0])
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return
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download = self.key_downloads.get(server_name)
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if download is None:
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download = self._get_server_verify_key_impl(server_name, key_ids)
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download = ObservableDeferred(
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download,
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consumeErrors=True
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)
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self.key_downloads[server_name] = download
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@download.addBoth
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def callback(ret):
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del self.key_downloads[server_name]
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return ret
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r = yield download.observe()
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defer.returnValue(r)
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@defer.inlineCallbacks
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def _get_server_verify_key_impl(self, server_name, key_ids):
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keys = None
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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, 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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logging.info(
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"Unable to getting key %r for %r from %r: %s %s",
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key_ids, server_name, perspective_name,
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type(e).__name__, str(e.message),
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)
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perspective_results = yield defer.gatherResults([
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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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for results in perspective_results:
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if results is not None:
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keys = results
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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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if not keys:
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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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logging.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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for key_id in key_ids:
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if key_id in keys:
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defer.returnValue(keys[key_id])
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return
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raise ValueError("No verification key found for given key ids")
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@defer.inlineCallbacks
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def get_server_verify_key_v2_indirect(self, server_name, key_ids,
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perspective_name,
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perspective_keys):
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limiter = yield get_retry_limiter(
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perspective_name, self.clock, self.store
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)
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with limiter:
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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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}
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},
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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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response_keys = yield self.process_v2_response(
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server_name, perspective_name, response
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)
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keys.update(response_keys)
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yield 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=keys,
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)
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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_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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server_name=server_name,
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from_server=server_name,
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requested_id=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 self.store_keys(
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server_name=server_name,
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from_server=server_name,
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verify_keys=keys,
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)
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defer.returnValue(keys)
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@defer.inlineCallbacks
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def process_v2_response(self, server_name, from_server, response_json,
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requested_id=None):
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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)
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verify_key = decode_verify_key_bytes(key_id, key_bytes)
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verify_key.expired = key_data["expired_ts"]
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verify_key.time_added = time_now_ms
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old_verify_keys[key_id] = verify_key
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for key_id in response_json["signatures"].get(server_name, {}):
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if key_id not in response_json["verify_keys"]:
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raise ValueError(
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"Key response must include verification keys for all"
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" signatures"
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)
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if key_id in verify_keys:
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verify_signed_json(
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response_json,
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server_name,
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verify_keys[key_id]
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)
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signed_key_json = sign_json(
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response_json,
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self.config.server_name,
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self.config.signing_key[0],
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)
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signed_key_json_bytes = encode_canonical_json(signed_key_json)
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ts_valid_until_ms = signed_key_json[u"valid_until_ts"]
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updated_key_ids = set()
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if requested_id is not None:
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updated_key_ids.add(requested_id)
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updated_key_ids.update(verify_keys)
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updated_key_ids.update(old_verify_keys)
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response_keys.update(verify_keys)
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response_keys.update(old_verify_keys)
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for key_id in updated_key_ids:
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yield self.store.store_server_keys_json(
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server_name=server_name,
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key_id=key_id,
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from_server=server_name,
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ts_now_ms=time_now_ms,
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ts_expires_ms=ts_valid_until_ms,
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key_json_bytes=signed_key_json_bytes,
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)
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defer.returnValue(response_keys)
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raise ValueError("No verification key found for given key ids")
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@defer.inlineCallbacks
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def get_server_verify_key_v1_direct(self, server_name, key_ids):
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"""Finds a verification key for the server with one of the key ids.
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Args:
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server_name (str): The name of the server to fetch a key for.
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keys_ids (list of str): The key_ids to check for.
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"""
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# Try to fetch the key from the remote server.
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(response, tls_certificate) = yield fetch_server_key(
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server_name, self.hs.tls_context_factory
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)
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# Check the response.
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x509_certificate_bytes = crypto.dump_certificate(
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crypto.FILETYPE_ASN1, tls_certificate
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)
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if ("signatures" not in response
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or server_name not in response["signatures"]):
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raise ValueError("Key response not signed by remote server")
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if "tls_certificate" not in response:
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raise ValueError("Key response missing TLS certificate")
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tls_certificate_b64 = response["tls_certificate"]
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if encode_base64(x509_certificate_bytes) != tls_certificate_b64:
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raise ValueError("TLS certificate doesn't match")
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# Cache the result in the datastore.
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time_now_ms = self.clock.time_msec()
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verify_keys = {}
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for key_id, key_base64 in response["verify_keys"].items():
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if is_signing_algorithm_supported(key_id):
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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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for key_id in response["signatures"][server_name]:
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if key_id not in response["verify_keys"]:
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raise ValueError(
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"Key response must include verification keys for all"
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" signatures"
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)
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if key_id in verify_keys:
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verify_signed_json(
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response,
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server_name,
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verify_keys[key_id]
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)
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yield self.store.store_server_certificate(
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server_name,
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server_name,
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time_now_ms,
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tls_certificate,
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)
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yield self.store_keys(
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server_name=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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defer.returnValue(verify_keys)
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@defer.inlineCallbacks
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def store_keys(self, server_name, from_server, verify_keys):
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"""Store a collection of verify keys for a given server
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Args:
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server_name(str): The name of the server the keys are for.
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from_server(str): The server the keys were downloaded from.
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verify_keys(dict): A mapping of key_id to VerifyKey.
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Returns:
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A deferred that completes when the keys are stored.
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"""
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for key_id, key in verify_keys.items():
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# TODO(markjh): Store whether the keys have expired.
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yield self.store.store_server_verify_key(
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server_name, server_name, key.time_added, key
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)
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