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Require sig from origin server on perspectives responses
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parent
ec24108cc2
commit
753b1270da
2 changed files with 91 additions and 23 deletions
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@ -394,8 +394,7 @@ class BaseV2KeyFetcher(object):
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POST /_matrix/key/v2/query.
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Checks that each signature in the response that claims to come from the origin
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server is valid. (Does not check that there actually is such a signature, for
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some reason.)
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server is valid, and that there is at least one such signature.
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Stores the json in server_keys_json so that it can be used for future responses
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to /_matrix/key/v2/query.
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@ -430,16 +429,25 @@ class BaseV2KeyFetcher(object):
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verify_key=verify_key, valid_until_ts=ts_valid_until_ms
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)
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# TODO: improve this signature checking
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server_name = response_json["server_name"]
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verified = False
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for key_id in response_json["signatures"].get(server_name, {}):
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if key_id not in verify_keys:
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# each of the keys used for the signature must be present in the response
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# json.
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key = verify_keys.get(key_id)
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if not key:
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raise KeyLookupError(
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"Key response must include verification keys for all signatures"
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"Key response is signed by key id %s:%s but that key is not "
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"present in the response" % (server_name, key_id)
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)
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verify_signed_json(
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response_json, server_name, verify_keys[key_id].verify_key
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verify_signed_json(response_json, server_name, key.verify_key)
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verified = True
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if not verified:
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raise KeyLookupError(
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"Key response for %s is not signed by the origin server"
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% (server_name,)
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)
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for key_id, key_data in response_json["old_verify_keys"].items():
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@ -677,12 +685,6 @@ class ServerKeyFetcher(BaseV2KeyFetcher):
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except HttpResponseException as e:
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raise_from(KeyLookupError("Remote server returned an error"), e)
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if (
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u"signatures" not in response
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or server_name not in response[u"signatures"]
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):
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raise KeyLookupError("Key response not signed by remote server")
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if response["server_name"] != server_name:
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raise KeyLookupError(
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"Expected a response for server %r not %r"
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@ -55,12 +55,12 @@ class MockPerspectiveServer(object):
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key_id: {"key": signedjson.key.encode_verify_key_base64(verify_key)}
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},
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}
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return self.get_signed_response(res)
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def get_signed_response(self, res):
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signedjson.sign.sign_json(res, self.server_name, self.key)
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self.sign_response(res)
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return res
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def sign_response(self, res):
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signedjson.sign.sign_json(res, self.server_name, self.key)
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class KeyringTestCase(unittest.HomeserverTestCase):
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def make_homeserver(self, reactor, clock):
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@ -238,7 +238,7 @@ class ServerKeyFetcherTestCase(unittest.HomeserverTestCase):
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testkey = signedjson.key.generate_signing_key("ver1")
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testverifykey = signedjson.key.get_verify_key(testkey)
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testverifykey_id = "ed25519:ver1"
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VALID_UNTIL_TS = 1000
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VALID_UNTIL_TS = 200 * 1000
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# valid response
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response = {
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@ -326,9 +326,10 @@ class PerspectivesKeyFetcherTestCase(unittest.HomeserverTestCase):
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},
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}
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persp_resp = {
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"server_keys": [self.mock_perspective_server.get_signed_response(response)]
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}
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# the response must be signed by both the origin server and the perspectives
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# server.
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signedjson.sign.sign_json(response, SERVER_NAME, testkey)
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self.mock_perspective_server.sign_response(response)
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def post_json(destination, path, data, **kwargs):
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self.assertEqual(destination, self.mock_perspective_server.server_name)
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@ -337,7 +338,7 @@ class PerspectivesKeyFetcherTestCase(unittest.HomeserverTestCase):
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# check that the request is for the expected key
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q = data["server_keys"]
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self.assertEqual(list(q[SERVER_NAME].keys()), ["key1"])
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return persp_resp
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return {"server_keys": [response]}
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self.http_client.post_json.side_effect = post_json
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@ -365,9 +366,74 @@ class PerspectivesKeyFetcherTestCase(unittest.HomeserverTestCase):
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self.assertEqual(
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bytes(res["key_json"]),
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canonicaljson.encode_canonical_json(persp_resp["server_keys"][0]),
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canonicaljson.encode_canonical_json(response),
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)
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def test_invalid_perspectives_responses(self):
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"""Check that invalid responses from the perspectives server are rejected"""
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# arbitrarily advance the clock a bit
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self.reactor.advance(100)
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SERVER_NAME = "server2"
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testkey = signedjson.key.generate_signing_key("ver1")
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testverifykey = signedjson.key.get_verify_key(testkey)
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testverifykey_id = "ed25519:ver1"
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VALID_UNTIL_TS = 200 * 1000
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def build_response():
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# valid response
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response = {
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"server_name": SERVER_NAME,
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"old_verify_keys": {},
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"valid_until_ts": VALID_UNTIL_TS,
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"verify_keys": {
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testverifykey_id: {
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"key": signedjson.key.encode_verify_key_base64(testverifykey)
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}
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},
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}
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# the response must be signed by both the origin server and the perspectives
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# server.
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signedjson.sign.sign_json(response, SERVER_NAME, testkey)
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self.mock_perspective_server.sign_response(response)
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return response
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def get_key_from_perspectives(response):
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fetcher = PerspectivesKeyFetcher(self.hs)
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server_name_and_key_ids = [(SERVER_NAME, ("key1",))]
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def post_json(destination, path, data, **kwargs):
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self.assertEqual(destination, self.mock_perspective_server.server_name)
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self.assertEqual(path, "/_matrix/key/v2/query")
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return {"server_keys": [response]}
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self.http_client.post_json.side_effect = post_json
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return self.get_success(
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fetcher.get_keys(server_name_and_key_ids)
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)
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# start with a valid response so we can check we are testing the right thing
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response = build_response()
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keys = get_key_from_perspectives(response)
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k = keys[SERVER_NAME][testverifykey_id]
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self.assertEqual(k.verify_key, testverifykey)
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# remove the perspectives server's signature
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response = build_response()
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del response["signatures"][self.mock_perspective_server.server_name]
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self.http_client.post_json.return_value = {"server_keys": [response]}
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keys = get_key_from_perspectives(response)
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self.assertEqual(keys, {}, "Expected empty dict with missing persp server sig")
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# remove the origin server's signature
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response = build_response()
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del response["signatures"][SERVER_NAME]
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self.http_client.post_json.return_value = {"server_keys": [response]}
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keys = get_key_from_perspectives(response)
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self.assertEqual(keys, {}, "Expected empty dict with missing origin server sig")
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@defer.inlineCallbacks
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def run_in_context(f, *args, **kwargs):
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