From c18b7b7819f17f5d14be1ba2760653f3d93b81b1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Florian=20M=C3=BCllner?= <fmuellner@gnome.org>
Date: Mon, 1 Feb 2021 18:26:00 +0100
Subject: [PATCH] extensionDownloader: Refuse to override system extensions

The website allows to "update" system extensions by installing the
upstream version into the user's home directory.

Prevent that by refusing to download and install extensions that are
already installed system-wide.
---
 js/ui/extensionDownloader.js | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/js/ui/extensionDownloader.js b/js/ui/extensionDownloader.js
index 6a3b2b488..471ddab14 100644
--- a/js/ui/extensionDownloader.js
+++ b/js/ui/extensionDownloader.js
@@ -17,6 +17,14 @@ var REPOSITORY_URL_UPDATE   = 'https://extensions.gnome.org/update-info/';
 let _httpSession;
 
 function installExtension(uuid, invocation) {
+    const oldExt = Main.extensionManager.lookup(uuid);
+    if (oldExt && oldExt.type === ExtensionUtils.ExtensionType.SYSTEM) {
+        log('extensionDownloader: Trying to replace system extension %s'.format(uuid));
+        invocation.return_dbus_error('org.gnome.Shell.InstallError',
+            'System extensions cannot be replaced');
+        return;
+    }
+
     let params = { uuid,
                    shell_version: Config.PACKAGE_VERSION };
 
-- 
2.31.1