Support 3PID login in password providers (#4931)

Adds a new method, check_3pid_auth, which gives password providers
the chance to allow authentication with third-party identifiers such
as email or msisdn.

changelog.d/4931.feature

@@ -0,0 +1 @@
+Add ability for password providers to login/register a user via 3PID (email, phone).

docs/password_auth_providers.rst

@@ -75,6 +75,20 @@ Password auth provider classes may optionally provide the following methods.
     result from the ``/login`` call (including ``access_token``, ``device_id``,
     etc.)
 
+``someprovider.check_3pid_auth``\(*medium*, *address*, *password*)
+
+    This method, if implemented, is called when a user attempts to register or
+    log in with a third party identifier, such as email. It is passed the
+    medium (ex. "email"), an address (ex. "[email protected]") and the user's
+    password.
+
+    The method should return a Twisted ``Deferred`` object, which resolves to
+    a ``str`` containing the user's (canonical) User ID if authentication was
+    successful, and ``None`` if not.
+
+    As with ``check_auth``, the ``Deferred`` may alternatively resolve to a
+    ``(user_id, callback)`` tuple.
+
 ``someprovider.check_password``\(*user_id*, *password*)
 
     This method provides a simpler interface than ``get_supported_login_types``

synapse/api/auth.py

@@ -621,13 +621,13 @@ def check_redaction(self, room_version, event, auth_events):
 
         Returns:
             True if the the sender is allowed to redact the target event if the
-            target event was created by them.
+                target event was created by them.
             False if the sender is allowed to redact the target event with no
-            further checks.
+                further checks.
 
         Raises:
             AuthError if the event sender is definitely not allowed to redact
-            the target event.
+                the target event.
         """
         return event_auth.check_redaction(room_version, event, auth_events)
 
@@ -743,9 +743,9 @@ def check_in_room_or_world_readable(self, room_id, user_id):
 
         Returns:
             Deferred[tuple[str, str|None]]: Resolves to the current membership of
-            the user in the room and the membership event ID of the user. If
-            the user is not in the room and never has been, then
-            `(Membership.JOIN, None)` is returned.
+                the user in the room and the membership event ID of the user. If
+                the user is not in the room and never has been, then
+                `(Membership.JOIN, None)` is returned.
         """
 
         try:
@@ -777,13 +777,13 @@ def check_auth_blocking(self, user_id=None, threepid=None):
 
         Args:
             user_id(str|None): If present, checks for presence against existing
-            MAU cohort
+                MAU cohort
 
             threepid(dict|None): If present, checks for presence against configured
-            reserved threepid. Used in cases where the user is trying register
-            with a MAU blocked server, normally they would be rejected but their
-            threepid is on the reserved list. user_id and
-            threepid should never be set at the same time.
+                reserved threepid. Used in cases where the user is trying register
+                with a MAU blocked server, normally they would be rejected but their
+                threepid is on the reserved list. user_id and
+                threepid should never be set at the same time.
         """
 
         # Never fail an auth check for the server notices users or support user

synapse/handlers/auth.py

@@ -745,6 +745,42 @@ def validate_login(self, username, login_submission):
             errcode=Codes.FORBIDDEN
         )
 
+    @defer.inlineCallbacks
+    def check_password_provider_3pid(self, medium, address, password):
+        """Check if a password provider is able to validate a thirdparty login
+
+        Args:
+            medium (str): The medium of the 3pid (ex. email).
+            address (str): The address of the 3pid (ex. [email protected]).
+            password (str): The password of the user.
+
+        Returns:
+            Deferred[(str|None, func|None)]: A tuple of `(user_id,
+            callback)`. If authentication is successful, `user_id` is a `str`
+            containing the authenticated, canonical user ID. `callback` is
+            then either a function to be later run after the server has
+            completed login/registration, or `None`. If authentication was
+            unsuccessful, `user_id` and `callback` are both `None`.
+        """
+        for provider in self.password_providers:
+            if hasattr(provider, "check_3pid_auth"):
+                # This function is able to return a deferred that either
+                # resolves None, meaning authentication failure, or upon
+                # success, to a str (which is the user_id) or a tuple of
+                # (user_id, callback_func), where callback_func should be run
+                # after we've finished everything else
+                result = yield provider.check_3pid_auth(
+                    medium, address, password,
+                )
+                if result:
+                    # Check if the return value is a str or a tuple
+                    if isinstance(result, str):
+                        # If it's a str, set callback function to None
+                        result = (result, None)
+                    defer.returnValue(result)
+
+        defer.returnValue((None, None))
+
     @defer.inlineCallbacks
     def _check_local_password(self, user_id, password):
         """Authenticate a user against the local password database.
@@ -756,7 +792,8 @@ def _check_local_password(self, user_id, password):
             user_id (unicode): complete @user:id
             password (unicode): the provided password
         Returns:
-            (unicode) the canonical_user_id, or None if unknown user / bad password
+            Deferred[unicode] the canonical_user_id, or Deferred[None] if
+                unknown user/bad password
 
         Raises:
             LimitExceededError if the ratelimiter's login requests count for this

synapse/handlers/profile.py

@@ -147,8 +147,14 @@ def get_displayname(self, target_user):
 
     @defer.inlineCallbacks
     def set_displayname(self, target_user, requester, new_displayname, by_admin=False):
-        """target_user is the user whose displayname is to be changed;
-        auth_user is the user attempting to make this change."""
+        """Set the displayname of a user
+
+        Args:
+            target_user (UserID): the user whose displayname is to be changed.
+            requester (Requester): The user attempting to make this change.
+            new_displayname (str): The displayname to give this user.
+            by_admin (bool): Whether this change was made by an administrator.
+        """
         if not self.hs.is_mine(target_user):
             raise SynapseError(400, "User is not hosted on this Home Server")
 

synapse/handlers/register.py

@@ -171,7 +171,7 @@ def register(
               api.constants.UserTypes, or None for a normal user.
             default_display_name (unicode|None): if set, the new user's displayname
               will be set to this. Defaults to 'localpart'.
-            address (str|None): the IP address used to perform the regitration.
+            address (str|None): the IP address used to perform the registration.
         Returns:
             A tuple of (user_id, access_token).
         Raises:
@@ -623,7 +623,7 @@ def register_with_store(self, user_id, token=None, password_hash=None,
             admin (boolean): is an admin user?
             user_type (str|None): type of user. One of the values from
                 api.constants.UserTypes, or None for a normal user.
-            address (str|None): the IP address used to perform the regitration.
+            address (str|None): the IP address used to perform the registration.
 
         Returns:
             Deferred
@@ -721,9 +721,9 @@ def post_registration_actions(self, user_id, auth_result, access_token,
             access_token (str|None): The access token of the newly logged in
                 device, or None if `inhibit_login` enabled.
             bind_email (bool): Whether to bind the email with the identity
-                server
+                server.
             bind_msisdn (bool): Whether to bind the msisdn with the identity
-                server
+                server.
         """
         if self.hs.config.worker_app:
             yield self._post_registration_client(
@@ -765,7 +765,7 @@ def _on_user_consented(self, user_id, consent_version):
         """A user consented to the terms on registration
 
         Args:
-            user_id (str): The user ID that consented
+            user_id (str): The user ID that consented.
             consent_version (str): version of the policy the user has
                 consented to.
         """

synapse/module_api/__init__.py

@@ -73,14 +73,26 @@ def check_user_exists(self, user_id):
         """
         return self._auth_handler.check_user_exists(user_id)
 
-    def register(self, localpart):
-        """Registers a new user with given localpart
+    @defer.inlineCallbacks
+    def register(self, localpart, displayname=None):
+        """Registers a new user with given localpart and optional
+           displayname.
+
+        Args:
+            localpart (str): The localpart of the new user.
+            displayname (str|None): The displayname of the new user. If None,
+                the user's displayname will default to `localpart`.
 
         Returns:
             Deferred: a 2-tuple of (user_id, access_token)
         """
+        # Register the user
         reg = self.hs.get_registration_handler()
-        return reg.register(localpart=localpart)
+        user_id, access_token = yield reg.register(
+            localpart=localpart, default_display_name=displayname,
+        )
+
+        defer.returnValue((user_id, access_token))
 
     @defer.inlineCallbacks
     def invalidate_access_token(self, access_token):

synapse/rest/client/v1/login.py

@@ -201,6 +201,24 @@ def _do_other_login(self, login_submission):
                 # We store all email addreses as lowercase in the DB.
                 # (See add_threepid in synapse/handlers/auth.py)
                 address = address.lower()
+
+            # Check for login providers that support 3pid login types
+            canonical_user_id, callback_3pid = (
+                yield self.auth_handler.check_password_provider_3pid(
+                    medium,
+                    address,
+                    login_submission["password"],
+                )
+            )
+            if canonical_user_id:
+                # Authentication through password provider and 3pid succeeded
+                result = yield self._register_device_with_callback(
+                    canonical_user_id, login_submission, callback_3pid,
+                )
+                defer.returnValue(result)
+
+            # No password providers were able to handle this 3pid
+            # Check local store
             user_id = yield self.hs.get_datastore().get_user_id_by_threepid(
                 medium, address,
             )
@@ -223,20 +241,43 @@ def _do_other_login(self, login_submission):
         if "user" not in identifier:
             raise SynapseError(400, "User identifier is missing 'user' key")
 
-        auth_handler = self.auth_handler
-        canonical_user_id, callback = yield auth_handler.validate_login(
+        canonical_user_id, callback = yield self.auth_handler.validate_login(
             identifier["user"],
             login_submission,
         )
 
+        result = yield self._register_device_with_callback(
+            canonical_user_id, login_submission, callback,
+        )
+        defer.returnValue(result)
+
+    @defer.inlineCallbacks
+    def _register_device_with_callback(
+        self,
+        user_id,
+        login_submission,
+        callback=None,
+    ):
+        """ Registers a device with a given user_id. Optionally run a callback
+        function after registration has completed.
+
+        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.
+
+        Returns:
+            result (Dict[str,str]): Dictionary of account information after
+                successful registration.
+        """
         device_id = login_submission.get("device_id")
         initial_display_name = login_submission.get("initial_device_display_name")
         device_id, access_token = yield self.registration_handler.register_device(
-            canonical_user_id, device_id, initial_display_name,
+            user_id, device_id, initial_display_name,
         )
 
         result = {
-            "user_id": canonical_user_id,
+            "user_id": user_id,
             "access_token": access_token,
             "home_server": self.hs.hostname,
             "device_id": device_id,