Add an openidish mechanism for proving to third parties that you own a given user_id

synapse/federation/federation_server.py

@@ -387,6 +387,11 @@ class FederationServer(FederationBase):
             "events": [ev.get_pdu_json(time_now) for ev in missing_events],
         })
 
+    @log_function
+    def on_openid_userinfo(self, token):
+        ts_now_ms = self._clock.time_msec()
+        return self.store.get_user_id_for_open_id_token(token, ts_now_ms)
+
     @log_function
     def _get_persisted_pdu(self, origin, event_id, do_auth=True):
         """ Get a PDU from the database with given origin and id.

synapse/federation/transport/server.py

@@ -18,7 +18,7 @@ from twisted.internet import defer
 from synapse.api.urls import FEDERATION_PREFIX as PREFIX
 from synapse.api.errors import Codes, SynapseError
 from synapse.http.server import JsonResource
-from synapse.http.servlet import parse_json_object_from_request
+from synapse.http.servlet import parse_json_object_from_request, parse_string
 from synapse.util.ratelimitutils import FederationRateLimiter
 
 import functools
@@ -448,6 +448,50 @@ class On3pidBindServlet(BaseFederationServlet):
         return code
 
 
+class OpenIdUserInfo(BaseFederationServlet):
+    """
+    Exchange a bearer token for information about a user.
+
+    The response format should be compatible with:
+        http://openid.net/specs/openid-connect-core-1_0.html#UserInfoResponse
+
+    GET /openid/userinfo?access_token=ABDEFGH HTTP/1.1
+
+    HTTP/1.1 200 OK
+    Content-Type: application/json
+
+    {
+        "sub": "@userpart:example.org",
+    }
+    """
+
+    PATH = "/openid/userinfo"
+
+    @defer.inlineCallbacks
+    def on_GET(self, request):
+        token = parse_string(request, "access_token")
+        if token is None:
+            defer.returnValue((401, {
+                "errcode": "M_MISSING_TOKEN", "error": "Access Token required"
+            }))
+            return
+
+        user_id = yield self.handler.on_openid_userinfo(token)
+
+        if user_id is None:
+            defer.returnValue((401, {
+                "errcode": "M_UNKNOWN_TOKEN",
+                "error": "Access Token unknown or expired"
+            }))
+
+        defer.returnValue((200, {"sub": user_id}))
+
+    # Avoid doing remote HS authorization checks which are done by default by
+    # BaseFederationServlet.
+    def _wrap(self, code):
+        return code
+
+
 SERVLET_CLASSES = (
     FederationSendServlet,
     FederationPullServlet,
@@ -468,6 +512,7 @@ SERVLET_CLASSES = (
     FederationClientKeysClaimServlet,
     FederationThirdPartyInviteExchangeServlet,
     On3pidBindServlet,
+    OpenIdUserInfo,
 )
 
 

synapse/rest/__init__.py

@@ -45,6 +45,7 @@ from synapse.rest.client.v2_alpha import (
     tags,
     account_data,
     report_event,
+    openid,
 )
 
 from synapse.http.server import JsonResource
@@ -88,3 +89,4 @@ class ClientRestResource(JsonResource):
         tags.register_servlets(hs, client_resource)
         account_data.register_servlets(hs, client_resource)
         report_event.register_servlets(hs, client_resource)
+        openid.register_servlets(hs, client_resource)

synapse/rest/client/v2_alpha/openid.py

@@ -0,0 +1,96 @@
+# -*- coding: utf-8 -*-
+# 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.
+
+
+from ._base import client_v2_patterns
+
+from synapse.http.servlet import RestServlet, parse_json_object_from_request
+from synapse.api.errors import AuthError
+from synapse.util.stringutils import random_string
+
+from twisted.internet import defer
+
+import logging
+
+logger = logging.getLogger(__name__)
+
+
+class IdTokenServlet(RestServlet):
+    """
+    Get a bearer token that may be passed to a third party to confirm ownership
+    of a matrix user id.
+
+    The format of the response could be made compatible with the format given
+    in http://openid.net/specs/openid-connect-core-1_0.html#TokenResponse
+
+    But instead of returning a signed "id_token" the response contains the
+    name of the issuing matrix homeserver. This means that for now the third
+    party will need to check the validity of the "id_token" against the
+    federation /openid/userinfo endpoint of the homeserver.
+
+    Request:
+
+    POST /user/{user_id}/openid/token?access_token=... HTTP/1.1
+
+    {}
+
+    Response:
+
+    HTTP/1.1 200 OK
+    {
+        "access_token": "ABDEFGH",
+        "token_type": "Bearer",
+        "matrix_server_name": "example.com",
+        "expires_in": 3600,
+    }
+    """
+    PATTERNS = client_v2_patterns(
+        "/user/(?P<user_id>[^/]*)/openid/token"
+    )
+
+    EXPIRES_MS = 3600 * 1000
+
+    def __init__(self, hs):
+        super(IdTokenServlet, self).__init__()
+        self.auth = hs.get_auth()
+        self.store = hs.get_datastore()
+        self.clock = hs.get_clock()
+        self.server_name = hs.config.server_name
+
+    @defer.inlineCallbacks
+    def on_POST(self, request, user_id):
+        requester = yield self.auth.get_user_by_req(request)
+        if user_id != requester.user.to_string():
+            raise AuthError(403, "Cannot request tokens for other users.")
+
+        # Parse the request body to make sure it's JSON, but ignore the contents
+        # for now.
+        parse_json_object_from_request(request)
+
+        token = random_string(24)
+        ts_valid_until_ms = self.clock.time_msec() + self.EXPIRES_MS
+
+        yield self.store.insert_open_id_token(token, ts_valid_until_ms, user_id)
+
+        defer.returnValue((200, {
+            "access_token": token,
+            "token_type": "Bearer",
+            "matrix_server_name": self.server_name,
+            "expires_in": self.EXPIRES_MS / 1000,
+        }))
+
+
+def register_servlets(hs, http_server):
+    IdTokenServlet(hs).register(http_server)

synapse/storage/__init__.py

@@ -44,6 +44,7 @@ from .receipts import ReceiptsStore
 from .search import SearchStore
 from .tags import TagsStore
 from .account_data import AccountDataStore
+from .openid import OpenIdStore
 
 from .util.id_generators import IdGenerator, StreamIdGenerator, ChainedIdGenerator
 
@@ -81,7 +82,8 @@ class DataStore(RoomMemberStore, RoomStore,
                 SearchStore,
                 TagsStore,
                 AccountDataStore,
-                EventPushActionsStore
+                EventPushActionsStore,
+                OpenIdStore,
                 ):
 
     def __init__(self, db_conn, hs):

synapse/storage/openid.py

@@ -0,0 +1,32 @@
+from ._base import SQLBaseStore
+
+
+class OpenIdStore(SQLBaseStore):
+    def insert_open_id_token(self, token, ts_valid_until_ms, user_id):
+        return self._simple_insert(
+            table="open_id_tokens",
+            values={
+                "token": token,
+                "ts_valid_until_ms": ts_valid_until_ms,
+                "user_id": user_id,
+            },
+            desc="insert_open_id_token"
+        )
+
+    def get_user_id_for_open_id_token(self, token, ts_now_ms):
+        def get_user_id_for_token_txn(txn):
+            sql = (
+                "SELECT user_id FROM open_id_tokens"
+                " WHERE token = ? AND ? <= ts_valid_until_ms"
+            )
+
+            txn.execute(sql, (token, ts_now_ms))
+
+            rows = txn.fetchall()
+            if not rows:
+                return None
+            else:
+                return rows[0][0]
+        return self.runInteraction(
+            "get_user_id_for_token", get_user_id_for_token_txn
+        )

synapse/storage/schema/delta/32/openid.sql

@@ -0,0 +1,9 @@
+
+CREATE TABLE open_id_tokens (
+    token TEXT NOT NULL PRIMARY KEY,
+    ts_valid_until_ms bigint NOT NULL,
+    user_id TEXT NOT NULL,
+    UNIQUE (token)
+);
+
+CREATE index open_id_tokens_ts_valid_until_ms ON open_id_tokens(ts_valid_until_ms);