Added possibilty to disable local password authentication (#5092)

Signed-off-by: Daniel Hoffend <dh@dotlan.net>

changelog.d/5092.feature

+Added possibilty to disable local password authentication. Contributed by Daniel Hoffend.

docs/sample_config.yaml

@@ -1046,6 +1046,12 @@ password_config:
    #
    #enabled: false
 
+   # Uncomment to disable authentication against the local password
+   # database. This is ignored if `enabled` is false, and is only useful
+   # if you have other password_providers.
+   #
+   #localdb_enabled: false
+
    # Uncomment and change to a secret random string for extra security.
    # DO NOT CHANGE THIS AFTER INITIAL SETUP!
    #

synapse/config/password.py

@@ -26,6 +26,7 @@ class PasswordConfig(Config):
             password_config = {}
 
         self.password_enabled = password_config.get("enabled", True)
+        self.password_localdb_enabled = password_config.get("localdb_enabled", True)
         self.password_pepper = password_config.get("pepper", "")
 
     def generate_config_section(self, config_dir_path, server_name, **kwargs):
@@ -35,6 +36,12 @@ class PasswordConfig(Config):
            #
            #enabled: false
 
+           # Uncomment to disable authentication against the local password
+           # database. This is ignored if `enabled` is false, and is only useful
+           # if you have other password_providers.
+           #
+           #localdb_enabled: false
+
            # Uncomment and change to a secret random string for extra security.
            # DO NOT CHANGE THIS AFTER INITIAL SETUP!
            #

synapse/handlers/auth.py

@@ -743,7 +743,7 @@ class AuthHandler(BaseHandler):
                     result = (result, None)
                 defer.returnValue(result)
 
-        if login_type == LoginType.PASSWORD:
+        if login_type == LoginType.PASSWORD and self.hs.config.password_localdb_enabled:
             known_login_type = True
 
             canonical_user_id = yield self._check_local_password(

synapse/handlers/set_password.py

@@ -33,6 +33,9 @@ class SetPasswordHandler(BaseHandler):
 
     @defer.inlineCallbacks
     def set_password(self, user_id, newpassword, requester=None):
+        if not self.hs.config.password_localdb_enabled:
+            raise SynapseError(403, "Password change disabled", errcode=Codes.FORBIDDEN)
+
         password_hash = yield self._auth_handler.hash(newpassword)
 
         except_device_id = requester.device_id if requester else None