Add JWT documentation and improve sample config

docs/dev/jwt.md

@@ -0,0 +1,70 @@
+# JWT Login Type
+
+Synapse comes with a non-standard login type to support
+[JSON Web Tokens](https://en.wikipedia.org/wiki/JSON_Web_Token). In general the
+documentation for
+[the login endpoint](https://matrix.org/docs/spec/client_server/r0.6.1#login)
+is still valid (and the mechanism works similarly to the
+[token based login](https://matrix.org/docs/spec/client_server/r0.6.1#token-based)).
+
+To log in using a JSON Web Token, clients should submit a `/login` request as
+follows:
+
+```json
+{
+  "type": "org.matrix.login.jwt",
+  "token": "<jwt>"
+}
+```
+
+Note that the login type of `m.login.jwt` is supported, but is deprecated. This
+will be removed in a future version of Synapse.
+
+The `jwt` should encode the local part of the user ID as the standard `sub`
+claim. In the case that the token is not valid, the homeserver must respond with
+`401 Unauthorized` and an error code of `M_UNAUTHORIZED`.
+
+(Note that this differs from the token based logins which return a
+`403 Forbidden` and an error code of `M_FORBIDDEN` if an error occurs.)
+
+As with other login types, there are additional fields (e.g. `device_id` and
+`initial_device_display_name`) which can be included in the above request.
+
+## How to test JWT as a developer
+
+Although JSON Web Tokens are typically generated from an external server, the
+examples below use [PyJWT](https://pyjwt.readthedocs.io/en/latest/) directly.
+
+1.  Configure Synapse with JWT logins:
+
+    ```yaml
+    jwt_config:
+        enabled: true
+        secret: "my-secret-token"
+        algorithm: "HS256"
+    ```
+2.  Generate a JSON web token:
+
+    ```bash
+    $ pyjwt --key=my-secret-token --alg=HS256 encode sub=test-user
+    eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ0ZXN0LXVzZXIifQ.Ag71GT8v01UO3w80aqRPTeuVPBIBZkYhNTJJ-_-zQIc
+    ```
+3.  Query for the login types and ensure `org.matrix.login.jwt` is there:
+
+    ```bash
+    curl http://localhost:8080/_matrix/client/r0/login
+    ```
+4.  Login used the generated JSON web token from above:
+
+    ```bash
+    $ curl http://localhost:8082/_matrix/client/r0/login -X POST \
+        --data '{"type":"org.matrix.login.jwt","token":"eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ0ZXN0LXVzZXIifQ.Ag71GT8v01UO3w80aqRPTeuVPBIBZkYhNTJJ-_-zQIc"}'
+    {
+        "access_token": "<access token>",
+        "device_id": "ACBDEFGHI",
+        "home_server": "localhost:8080",
+        "user_id": "@test-user:localhost:8480"
+    }
+    ```
+
+You should now be able to use the returned access token to query the client API.

docs/sample_config.yaml

@@ -1804,12 +1804,19 @@ sso:
     #template_dir: "res/templates"
 
 
-# The JWT needs to contain a globally unique "sub" (subject) claim.
+# Configure the non-standard JSON Web Token login type.
+#
+# Each JSON Web Token needs to contain a "sub" (subject) claim, which is
+# used as the localpart of the mxid.
 #
 #jwt_config:
-#   enabled: true
-#   secret: "a secret"
-#   algorithm: "HS256"
+    # Uncomment the following to enable JWT logins.
+    #enabled: true
+    # This is either the private secret or the public key used to decode
+    # the contents of the JWT.
+    #secret: "a secret"
+    # The algorithm used to sign the JWT.
+    #algorithm: "HS256"
 
 
 password_config:

synapse/config/jwt_config.py

@@ -45,10 +45,17 @@ def read_config(self, config, **kwargs):
 
     def generate_config_section(self, **kwargs):
         return """\
-        # The JWT needs to contain a globally unique "sub" (subject) claim.
+        # Configure the non-standard JSON Web Token login type.
+        #
+        # Each JSON Web Token needs to contain a "sub" (subject) claim, which is
+        # used as the localpart of the mxid.
         #
         #jwt_config:
-        #   enabled: true
-        #   secret: "a secret"
-        #   algorithm: "HS256"
+            # Uncomment the following to enable JWT logins.
+            #enabled: true
+            # This is either the private secret or the public key used to decode
+            # the contents of the JWT.
+            #secret: "a secret"
+            # The algorithm used to sign the JWT.
+            #algorithm: "HS256"
         """

synapse/rest/client/v1/login.py

@@ -14,6 +14,7 @@
 # limitations under the License.
 
 import logging
+from typing import Awaitable, Callable, Dict, Optional
 
 from synapse.api.errors import Codes, LoginError, SynapseError
 from synapse.api.ratelimiting import Ratelimiter
@@ -26,7 +27,7 @@
 from synapse.http.site import SynapseRequest
 from synapse.rest.client.v2_alpha._base import client_patterns
 from synapse.rest.well_known import WellKnownBuilder
-from synapse.types import UserID
+from synapse.types import JsonDict, UserID
 from synapse.util.msisdn import phone_number_to_msisdn
 
 logger = logging.getLogger(__name__)
@@ -113,7 +114,7 @@ def __init__(self, hs):
             burst_count=self.hs.config.rc_login_failed_attempts.burst_count,
         )
 
-    def on_GET(self, request):
+    def on_GET(self, request: SynapseRequest):
         flows = []
         if self.jwt_enabled:
             flows.append({"type": LoginRestServlet.JWT_TYPE})
@@ -141,10 +142,10 @@ def on_GET(self, request):
 
         return 200, {"flows": flows}
 
-    def on_OPTIONS(self, request):
+    def on_OPTIONS(self, request: SynapseRequest):
         return 200, {}
 
-    async def on_POST(self, request):
+    async def on_POST(self, request: SynapseRequest):
         self._address_ratelimiter.ratelimit(request.getClientIP())
 
         login_submission = parse_json_object_from_request(request)
@@ -153,9 +154,9 @@ async def on_POST(self, request):
                 login_submission["type"] == LoginRestServlet.JWT_TYPE
                 or login_submission["type"] == LoginRestServlet.JWT_TYPE_DEPRECATED
             ):
-                result = await self.do_jwt_login(login_submission)
+                result = await self._do_jwt_login(login_submission)
             elif login_submission["type"] == LoginRestServlet.TOKEN_TYPE:
-                result = await self.do_token_login(login_submission)
+                result = await self._do_token_login(login_submission)
             else:
                 result = await self._do_other_login(login_submission)
         except KeyError:
@@ -166,7 +167,7 @@ async def on_POST(self, request):
             result["well_known"] = well_known_data
         return 200, result
 
-    async def _do_other_login(self, login_submission):
+    async def _do_other_login(self, login_submission: JsonDict):
         """Handle non-token/saml/jwt logins
 
         Args:
@@ -288,25 +289,30 @@ async def _do_other_login(self, login_submission):
         return result
 
     async def _complete_login(
-        self, user_id, login_submission, callback=None, create_non_existent_users=False
+        self,
+        user_id: str,
+        login_submission: JsonDict,
+        callback: Optional[
+            Callable[[Dict[str, str]], Awaitable[Dict[str, str]]]
+        ] = None,
+        create_non_existent_users: bool = False,
     ):
         """Called when we've successfully authed the user and now need to
         actually login them in (e.g. create devices). This gets called on
-        all succesful logins.
+        all successful logins.
 
-        Applies the ratelimiting for succesful login attempts against an
+        Applies the ratelimiting for successful login attempts against an
         account.
 
         Args:
-            user_id (str): ID of the user to register.
-            login_submission (dict): Dictionary of login information.
-            callback (func|None): Callback function to run after registration.
-            create_non_existent_users (bool): Whether to create the user if
-                they don't exist. Defaults to False.
+            user_id: ID of the user to register.
+            login_submission: Dictionary of login information.
+            callback: Callback function to run after registration.
+            create_non_existent_users: Whether to create the user if they don't
+                exist. Defaults to False.
 
         Returns:
-            result (Dict[str,str]): Dictionary of account information after
-                successful registration.
+            result: Dictionary of account information after successful registration.
         """
 
         # Before we actually log them in we check if they've already logged in
@@ -340,7 +346,7 @@ async def _complete_login(
 
         return result
 
-    async def do_token_login(self, login_submission):
+    async def _do_token_login(self, login_submission: JsonDict):
         token = login_submission["token"]
         auth_handler = self.auth_handler
         user_id = await auth_handler.validate_short_term_login_token_and_get_user_id(
@@ -350,7 +356,7 @@ async def do_token_login(self, login_submission):
         result = await self._complete_login(user_id, login_submission)
         return result
 
-    async def do_jwt_login(self, login_submission):
+    async def _do_jwt_login(self, login_submission: JsonDict):
         token = login_submission.get("token", None)
         if token is None:
             raise LoginError(