SYN-75 Verify signatures on server to server transactions

4 files changed, 154 insertions, 172 deletions

diff --git a/synapse/crypto/keyclient.py b/synapse/crypto/keyclient.py
index c11df5c529..c26f16a038 100644
--- a/synapse/crypto/keyclient.py
+++ b/synapse/crypto/keyclient.py
@@ -15,9 +15,10 @@
 
 
 from twisted.web.http import HTTPClient
+from twisted.internet.protocol import Factory
 from twisted.internet import defer, reactor
-from twisted.internet.protocol import ClientFactory
-from twisted.names.srvconnect import SRVConnector
+from twisted.internet.endpoints import connectProtocol
+from synapse.http.endpoint import matrix_endpoint
 import json
 import logging
 
@@ -30,15 +31,19 @@ def fetch_server_key(server_name, ssl_context_factory):
     """Fetch the keys for a remote server."""
 
     factory = SynapseKeyClientFactory()
+    endpoint = matrix_endpoint(
+        reactor, server_name, ssl_context_factory, timeout=30
+    )
 
-    SRVConnector(
-        reactor, "matrix", server_name, factory,
-        protocol="tcp", connectFuncName="connectSSL", defaultPort=443,
-        connectFuncKwArgs=dict(contextFactory=ssl_context_factory)).connect()
-
-    server_key, server_certificate = yield factory.remote_key
-
-    defer.returnValue((server_key, server_certificate))
+    for i in range(5):
+        try:
+            protocol = yield endpoint.connect(factory)
+            server_response, server_certificate = yield protocol.remote_key
+            defer.returnValue((server_response, server_certificate))
+            return
+        except Exception as e:
+            logger.exception(e)
+    raise IOError("Cannot get key for " % server_name)
 
 
 class SynapseKeyClientError(Exception):
@@ -51,69 +56,47 @@ class SynapseKeyClientProtocol(HTTPClient):
     the server and extracts the X.509 certificate for the remote peer from the
     SSL connection."""
 
+    timeout = 30
+
+    def __init__(self):
+        self.remote_key = defer.Deferred()
+
     def connectionMade(self):
         logger.debug("Connected to %s", self.transport.getHost())
-        self.sendCommand(b"GET", b"/key")
+        self.sendCommand(b"GET", b"/_matrix/key/v1/")
         self.endHeaders()
         self.timer = reactor.callLater(
-            self.factory.timeout_seconds,
+            self.timeout,
             self.on_timeout
         )
 
     def handleStatus(self, version, status, message):
         if status != b"200":
-            logger.info("Non-200 response from %s: %s %s",
-                        self.transport.getHost(), status, message)
+            #logger.info("Non-200 response from %s: %s %s",
+            #            self.transport.getHost(), status, message)
             self.transport.abortConnection()
 
     def handleResponse(self, response_body_bytes):
         try:
             json_response = json.loads(response_body_bytes)
         except ValueError:
-            logger.info("Invalid JSON response from %s",
-                        self.transport.getHost())
+            #logger.info("Invalid JSON response from %s",
+            #            self.transport.getHost())
             self.transport.abortConnection()
             return
 
         certificate = self.transport.getPeerCertificate()
-        self.factory.on_remote_key((json_response, certificate))
+        self.remote_key.callback((json_response, certificate))
         self.transport.abortConnection()
         self.timer.cancel()
 
     def on_timeout(self):
         logger.debug("Timeout waiting for response from %s",
                      self.transport.getHost())
+        self.on_remote_key.errback(IOError("Timeout waiting for response"))
         self.transport.abortConnection()
 
 
-class SynapseKeyClientFactory(ClientFactory):
+class SynapseKeyClientFactory(Factory):
     protocol = SynapseKeyClientProtocol
-    max_retries = 5
-    timeout_seconds = 30
-
-    def __init__(self):
-        self.succeeded = False
-        self.retries = 0
-        self.remote_key = defer.Deferred()
 
-    def on_remote_key(self, key):
-        self.succeeded = True
-        self.remote_key.callback(key)
-
-    def retry_connection(self, connector):
-        self.retries += 1
-        if self.retries < self.max_retries:
-            connector.connector = None
-            connector.connect()
-        else:
-            self.remote_key.errback(
-                SynapseKeyClientError("Max retries exceeded"))
-
-    def clientConnectionFailed(self, connector, reason):
-        logger.info("Connection failed %s", reason)
-        self.retry_connection(connector)
-
-    def clientConnectionLost(self, connector, reason):
-        logger.info("Connection lost %s", reason)
-        if not self.succeeded:
-            self.retry_connection(connector)
diff --git a/synapse/crypto/keyring.py b/synapse/crypto/keyring.py
new file mode 100644
index 0000000000..ce19c69bd5
--- /dev/null
+++ b/synapse/crypto/keyring.py
@@ -0,0 +1,125 @@
+# -*- coding: utf-8 -*-
+# Copyright 2014 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.
+
+from synapse.crypto.keyclient import fetch_server_key
+from twisted.internet import defer
+from syutil.crypto.jsonsign import verify_signed_json, signature_ids
+from syutil.crypto.signing_key import (
+    is_signing_algorithm_supported, decode_verify_key_bytes
+)
+from syutil.base64util import decode_base64, encode_base64
+
+from OpenSSL import crypto
+
+import logging
+
+
+logger = logging.getLogger(__name__)
+
+
+class Keyring(object):
+    def __init__(self, hs):
+        self.store = hs.get_datastore()
+        self.clock = hs.get_clock()
+        self.hs = hs
+
+    @defer.inlineCallbacks
+    def verify_json_for_server(self, server_name, json_object):
+        key_ids = signature_ids(json_object, server_name)
+        verify_key = yield self.get_server_verify_key(server_name, key_ids)
+        verify_signed_json(json_object, server_name, verify_key)
+
+    @defer.inlineCallbacks
+    def get_server_verify_key(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.
+        """
+
+        # Check the datastore to see if we have one cached.
+        cached = yield self.store.get_server_verify_keys(server_name, key_ids)
+
+        if cached:
+            defer.returnValue(cached[0])
+            return
+
+        # Try to fetch the key from the remote server.
+        # TODO(markjh): Ratelimit requests to a given server.
+
+        (response, tls_certificate) = yield fetch_server_key(
+            server_name, self.hs.tls_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")
+
+        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_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]
+                )
+
+        # Cache the result in the datastore.
+
+        time_now_ms = self.clock.time_msec()
+
+        self.store.store_server_certificate(
+            server_name,
+            server_name,
+            time_now_ms,
+            tls_certificate,
+        )
+
+        for key_id, key in verify_keys.items():
+            self.store.store_server_verify_key(
+                server_name, server_name, time_now_ms, key
+            )
+
+        for key_id in key_ids:
+            if key_id in verify_keys:
+                defer.returnValue(verify_keys[key_id])
+                return
+
+        raise ValueError("No verification key found for given key ids")
diff --git a/synapse/crypto/keyserver.py b/synapse/crypto/keyserver.py
deleted file mode 100644
index a23484dbae..0000000000
--- a/synapse/crypto/keyserver.py
+++ /dev/null
@@ -1,111 +0,0 @@
-# -*- coding: utf-8 -*-
-# Copyright 2014 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.
-
-
-from twisted.internet import reactor, ssl
-from twisted.web import server
-from twisted.web.resource import Resource
-from twisted.python.log import PythonLoggingObserver
-
-from synapse.crypto.resource.key import LocalKey
-from synapse.crypto.config import load_config
-
-from syutil.base64util import decode_base64
-
-from OpenSSL import crypto, SSL
-
-import logging
-import nacl.signing
-import sys
-
-
-class KeyServerSSLContextFactory(ssl.ContextFactory):
-    """Factory for PyOpenSSL SSL contexts that are used to handle incoming
-    connections and to make connections to remote servers."""
-
-    def __init__(self, key_server):
-        self._context = SSL.Context(SSL.SSLv23_METHOD)
-        self.configure_context(self._context, key_server)
-
-    @staticmethod
-    def configure_context(context, key_server):
-        context.set_options(SSL.OP_NO_SSLv2 | SSL.OP_NO_SSLv3)
-        context.use_certificate(key_server.tls_certificate)
-        context.use_privatekey(key_server.tls_private_key)
-        context.load_tmp_dh(key_server.tls_dh_params_path)
-        context.set_cipher_list("!ADH:HIGH+kEDH:!AECDH:HIGH+kEECDH")
-
-    def getContext(self):
-        return self._context
-
-
-class KeyServer(object):
-    """An HTTPS server serving LocalKey and RemoteKey resources."""
-
-    def __init__(self, server_name, tls_certificate_path, tls_private_key_path,
-                 tls_dh_params_path, signing_key_path, bind_host, bind_port):
-        self.server_name = server_name
-        self.tls_certificate = self.read_tls_certificate(tls_certificate_path)
-        self.tls_private_key = self.read_tls_private_key(tls_private_key_path)
-        self.tls_dh_params_path = tls_dh_params_path
-        self.signing_key = self.read_signing_key(signing_key_path)
-        self.bind_host = bind_host
-        self.bind_port = int(bind_port)
-        self.ssl_context_factory = KeyServerSSLContextFactory(self)
-
-    @staticmethod
-    def read_tls_certificate(cert_path):
-        with open(cert_path) as cert_file:
-            cert_pem = cert_file.read()
-            return crypto.load_certificate(crypto.FILETYPE_PEM, cert_pem)
-
-    @staticmethod
-    def read_tls_private_key(private_key_path):
-        with open(private_key_path) as private_key_file:
-            private_key_pem = private_key_file.read()
-            return crypto.load_privatekey(crypto.FILETYPE_PEM, private_key_pem)
-
-    @staticmethod
-    def read_signing_key(signing_key_path):
-        with open(signing_key_path) as signing_key_file:
-            signing_key_b64 = signing_key_file.read()
-            signing_key_bytes = decode_base64(signing_key_b64)
-            return nacl.signing.SigningKey(signing_key_bytes)
-
-    def run(self):
-        root = Resource()
-        root.putChild("key", LocalKey(self))
-        site = server.Site(root)
-        reactor.listenSSL(
-            self.bind_port,
-            site,
-            self.ssl_context_factory,
-            interface=self.bind_host
-        )
-
-        logging.basicConfig(level=logging.DEBUG)
-        observer = PythonLoggingObserver()
-        observer.start()
-
-        reactor.run()
-
-
-def main():
-    key_server = KeyServer(**load_config(__doc__, sys.argv[1:]))
-    key_server.run()
-
-
-if __name__ == "__main__":
-    main()
diff --git a/synapse/crypto/resource/__init__.py b/synapse/crypto/resource/__init__.py
deleted file mode 100644
index 9bff9ec169..0000000000
--- a/synapse/crypto/resource/__init__.py
+++ /dev/null
@@ -1,15 +0,0 @@
-# -*- coding: utf-8 -*-
-# Copyright 2014 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.
-