Do not allow a deactivated user to login via SSO.

changelog.d/7240.bugfix

@@ -0,0 +1 @@
+Do not allow a deactivated user to login via SSO.

synapse/handlers/auth.py

@@ -161,6 +161,10 @@ def __init__(self, hs):
         self._sso_auth_confirm_template = load_jinja2_templates(
             hs.config.sso_redirect_confirm_template_dir, ["sso_auth_confirm.html"],
         )[0]
+        self._sso_account_deactivated_template = load_jinja2_templates(
+            hs.config.sso_redirect_confirm_template_dir,
+            ["sso_account_deactivated.html"],
+        )[0]
 
         self._server_name = hs.config.server_name
 
@@ -644,9 +648,6 @@ def check_user_exists(self, user_id: str):
         Returns:
             defer.Deferred: (unicode) canonical_user_id, or None if zero or
             multiple matches
-
-        Raises:
-            UserDeactivatedError if a user is found but is deactivated.
         """
         res = yield self._find_user_id_and_pwd_hash(user_id)
         if res is not None:
@@ -1099,7 +1100,7 @@ def complete_sso_ui_auth(
         request.write(html_bytes)
         finish_request(request)
 
-    def complete_sso_login(
+    async def complete_sso_login(
         self,
         registered_user_id: str,
         request: SynapseRequest,
@@ -1113,6 +1114,31 @@ def complete_sso_login(
             client_redirect_url: The URL to which to redirect the user at the end of the
                 process.
         """
+        # If the password hash is None, the account has likely been deactivated
+        deactivated = await self.store.get_user_deactivated_status(registered_user_id)
+        if deactivated:
+            html = self._sso_account_deactivated_template.render().encode("utf-8")
+
+            request.setResponseCode(403)
+            request.setHeader(b"Content-Type", b"text/html; charset=utf-8")
+            request.setHeader(b"Content-Length", b"%d" % (len(html),))
+            request.write(html)
+            finish_request(request)
+            return
+
+        self._complete_sso_login(registered_user_id, request, client_redirect_url)
+
+    def _complete_sso_login(
+        self,
+        registered_user_id: str,
+        request: SynapseRequest,
+        client_redirect_url: str,
+    ):
+        """
+        The synchronous portion of complete_sso_login.
+
+        This exists purely for backwards compatibility of synapse.module_api.ModuleApi.
+        """
         # Create a login token
         login_token = self.macaroon_gen.generate_short_term_login_token(
             registered_user_id

synapse/handlers/cas_handler.py

@@ -216,6 +216,6 @@ async def handle_ticket(
                     localpart=localpart, default_display_name=user_display_name
                 )
 
-            self._auth_handler.complete_sso_login(
+            await self._auth_handler.complete_sso_login(
                 registered_user_id, request, client_redirect_url
             )

synapse/handlers/saml_handler.py

@@ -154,7 +154,7 @@ async def handle_saml_response(self, request):
             )
 
         else:
-            self._auth_handler.complete_sso_login(user_id, request, relay_state)
+            await self._auth_handler.complete_sso_login(user_id, request, relay_state)
 
     async def _map_saml_response_to_user(
         self, resp_bytes: str, client_redirect_url: str

synapse/module_api/__init__.py

@@ -220,13 +220,33 @@ def complete_sso_login(
         want their access token sent to `client_redirect_url`, or redirect them to that
         URL with a token directly if the URL matches with one of the whitelisted clients.
 
+        This is deprecated in favor of complete_sso_login_async.
+
+        Args:
+            registered_user_id: The MXID that has been registered as a previous step of
+                of this SSO login.
+            request: The request to respond to.
+            client_redirect_url: The URL to which to offer to redirect the user (or to
+                redirect them directly if whitelisted).
+        """
+        self._auth_handler._complete_sso_login(
+            registered_user_id, request, client_redirect_url,
+        )
+
+    async def complete_sso_login_async(
+        self, registered_user_id: str, request: SynapseRequest, client_redirect_url: str
+    ):
+        """Complete a SSO login by redirecting the user to a page to confirm whether they
+        want their access token sent to `client_redirect_url`, or redirect them to that
+        URL with a token directly if the URL matches with one of the whitelisted clients.
+
         Args:
             registered_user_id: The MXID that has been registered as a previous step of
                 of this SSO login.
             request: The request to respond to.
             client_redirect_url: The URL to which to offer to redirect the user (or to
                 redirect them directly if whitelisted).
         """
-        self._auth_handler.complete_sso_login(
+        await self._auth_handler.complete_sso_login(
             registered_user_id, request, client_redirect_url,
         )

synapse/res/templates/sso_account_deactivated.html

@@ -0,0 +1,10 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <title>SSO account deactivated</title>
+</head>
+    <body>
+        <p>This account has been deactivated.</p>
+    </body>
+</html>