1 files changed, 29 insertions, 0 deletions
diff --git a/browser/extensions/webcompat/shims/microsoftLogin.js b/browser/extensions/webcompat/shims/microsoftLogin.js
new file mode 100644
index 0000000000..ebbfb2fbff
--- /dev/null
+++ b/browser/extensions/webcompat/shims/microsoftLogin.js
@@ -0,0 +1,29 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const SANDBOX_ATTR = "allow-storage-access-by-user-activation";
+
+console.warn(
+  "Firefox calls the Storage Access API on behalf of the site. See https://bugzilla.mozilla.org/show_bug.cgi?id=1638383 for details."
+);
+
+// Watches for MS auth iframes and adds missing sandbox attribute. The attribute
+// is required so the third-party iframe can gain access to its first party
+// storage via the Storage Access API.
+function init() {
+  const observer = new MutationObserver(() => {
+    document.body
+      .querySelectorAll("iframe[id^='msalRenewFrame'][sandbox]")
+      .forEach(frame => {
+        frame.sandbox.add(SANDBOX_ATTR);
+      });
+  });
+
+  observer.observe(document.body, {
+    attributes: true,
+    subtree: false,
+    childList: true,
+  });
+}
+window.addEventListener("DOMContentLoaded", init);