forked-synapse/synapse/rest/key/v2/remote_key_resource.py
Richard van der Hoff 573fee759c
Back out ill-advised notary server hackery (#6657)
This was ill-advised. We can't modify verify_keys here, because the response
object has already been signed by the requested key.

Furthermore, it's somewhat unnecessary because existing versions of Synapse
(which get upset that the notary key isn't present in verify_keys) will fall
back to a direct fetch via `/key/v2/server`.

Also: more tests for fetching keys via perspectives: it would be nice if we actually tested when our fetcher can't talk to our notary impl.
2020-01-08 13:24:10 +00:00

231 lines
8.6 KiB
Python

# Copyright 2015, 2016 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
from canonicaljson import encode_canonical_json, json
from signedjson.sign import sign_json
from twisted.internet import defer
from synapse.api.errors import Codes, SynapseError
from synapse.crypto.keyring import ServerKeyFetcher
from synapse.http.server import (
DirectServeResource,
respond_with_json_bytes,
wrap_json_request_handler,
)
from synapse.http.servlet import parse_integer, parse_json_object_from_request
logger = logging.getLogger(__name__)
class RemoteKey(DirectServeResource):
"""HTTP resource for retreiving the TLS certificate and NACL signature
verification keys for a collection of servers. Checks that the reported
X.509 TLS certificate matches the one used in the HTTPS connection. Checks
that the NACL signature for the remote server is valid. Returns a dict of
JSON signed by both the remote server and by this server.
Supports individual GET APIs and a bulk query POST API.
Requsts:
GET /_matrix/key/v2/query/remote.server.example.com HTTP/1.1
GET /_matrix/key/v2/query/remote.server.example.com/a.key.id HTTP/1.1
POST /_matrix/v2/query HTTP/1.1
Content-Type: application/json
{
"server_keys": {
"remote.server.example.com": {
"a.key.id": {
"minimum_valid_until_ts": 1234567890123
}
}
}
}
Response:
HTTP/1.1 200 OK
Content-Type: application/json
{
"server_keys": [
{
"server_name": "remote.server.example.com"
"valid_until_ts": # posix timestamp
"verify_keys": {
"a.key.id": { # The identifier for a key.
key: "" # base64 encoded verification key.
}
}
"old_verify_keys": {
"an.old.key.id": { # The identifier for an old key.
key: "", # base64 encoded key
"expired_ts": 0, # when the key stop being used.
}
}
"tls_fingerprints": [
{ "sha256": # fingerprint }
]
"signatures": {
"remote.server.example.com": {...}
"this.server.example.com": {...}
}
}
]
}
"""
isLeaf = True
def __init__(self, hs):
self.fetcher = ServerKeyFetcher(hs)
self.store = hs.get_datastore()
self.clock = hs.get_clock()
self.federation_domain_whitelist = hs.config.federation_domain_whitelist
self.config = hs.config
@wrap_json_request_handler
async def _async_render_GET(self, request):
if len(request.postpath) == 1:
(server,) = request.postpath
query = {server.decode("ascii"): {}}
elif len(request.postpath) == 2:
server, key_id = request.postpath
minimum_valid_until_ts = parse_integer(request, "minimum_valid_until_ts")
arguments = {}
if minimum_valid_until_ts is not None:
arguments["minimum_valid_until_ts"] = minimum_valid_until_ts
query = {server.decode("ascii"): {key_id.decode("ascii"): arguments}}
else:
raise SynapseError(404, "Not found %r" % request.postpath, Codes.NOT_FOUND)
await self.query_keys(request, query, query_remote_on_cache_miss=True)
@wrap_json_request_handler
async def _async_render_POST(self, request):
content = parse_json_object_from_request(request)
query = content["server_keys"]
await self.query_keys(request, query, query_remote_on_cache_miss=True)
@defer.inlineCallbacks
def query_keys(self, request, query, query_remote_on_cache_miss=False):
logger.info("Handling query for keys %r", query)
store_queries = []
for server_name, key_ids in query.items():
if (
self.federation_domain_whitelist is not None
and server_name not in self.federation_domain_whitelist
):
logger.debug("Federation denied with %s", server_name)
continue
if not key_ids:
key_ids = (None,)
for key_id in key_ids:
store_queries.append((server_name, key_id, None))
cached = yield self.store.get_server_keys_json(store_queries)
json_results = set()
time_now_ms = self.clock.time_msec()
cache_misses = dict()
for (server_name, key_id, from_server), results in cached.items():
results = [(result["ts_added_ms"], result) for result in results]
if not results and key_id is not None:
cache_misses.setdefault(server_name, set()).add(key_id)
continue
if key_id is not None:
ts_added_ms, most_recent_result = max(results)
ts_valid_until_ms = most_recent_result["ts_valid_until_ms"]
req_key = query.get(server_name, {}).get(key_id, {})
req_valid_until = req_key.get("minimum_valid_until_ts")
miss = False
if req_valid_until is not None:
if ts_valid_until_ms < req_valid_until:
logger.debug(
"Cached response for %r/%r is older than requested"
": valid_until (%r) < minimum_valid_until (%r)",
server_name,
key_id,
ts_valid_until_ms,
req_valid_until,
)
miss = True
else:
logger.debug(
"Cached response for %r/%r is newer than requested"
": valid_until (%r) >= minimum_valid_until (%r)",
server_name,
key_id,
ts_valid_until_ms,
req_valid_until,
)
elif (ts_added_ms + ts_valid_until_ms) / 2 < time_now_ms:
logger.debug(
"Cached response for %r/%r is too old"
": (added (%r) + valid_until (%r)) / 2 < now (%r)",
server_name,
key_id,
ts_added_ms,
ts_valid_until_ms,
time_now_ms,
)
# We more than half way through the lifetime of the
# response. We should fetch a fresh copy.
miss = True
else:
logger.debug(
"Cached response for %r/%r is still valid"
": (added (%r) + valid_until (%r)) / 2 < now (%r)",
server_name,
key_id,
ts_added_ms,
ts_valid_until_ms,
time_now_ms,
)
if miss:
cache_misses.setdefault(server_name, set()).add(key_id)
json_results.add(bytes(most_recent_result["key_json"]))
else:
for ts_added, result in results:
json_results.add(bytes(result["key_json"]))
if cache_misses and query_remote_on_cache_miss:
yield self.fetcher.get_keys(cache_misses)
yield self.query_keys(request, query, query_remote_on_cache_miss=False)
else:
signed_keys = []
for key_json in json_results:
key_json = json.loads(key_json)
for signing_key in self.config.key_server_signing_keys:
key_json = sign_json(key_json, self.config.server_name, signing_key)
signed_keys.append(key_json)
results = {"server_keys": signed_keys}
respond_with_json_bytes(request, 200, encode_canonical_json(results))