diff --git a/extensions/cookie/nsPermissionManager.cpp b/extensions/cookie/nsPermissionManager.cpp
index 1979fe696afe..6cd0ab079803 100644
--- a/extensions/cookie/nsPermissionManager.cpp
+++ b/extensions/cookie/nsPermissionManager.cpp
@@ -2245,6 +2245,36 @@ NS_IMETHODIMP nsPermissionManager::GetEnumerator(nsISimpleEnumerator **aEnum)
   return NS_NewArrayEnumerator(aEnum, array);
 }
 
+NS_IMETHODIMP nsPermissionManager::GetAllForURI(nsIURI* aURI, nsISimpleEnumerator **aEnum)
+{
+  nsCOMArray<nsIPermission> array;
+
+  nsCOMPtr<nsIPrincipal> principal;
+  nsresult rv = GetPrincipal(aURI, getter_AddRefs(principal));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  RefPtr<PermissionKey> key = new PermissionKey(principal);
+  PermissionHashKey* entry = mPermissionTable.GetEntry(key);
+
+  if (entry) {
+    for (const auto& permEntry : entry->GetPermissions()) {
+      // Only return custom permissions
+      if (permEntry.mPermission == nsIPermissionManager::UNKNOWN_ACTION) {
+        continue;
+      }
+
+      array.AppendObject(
+        new nsPermission(principal,
+                         mTypeArray.ElementAt(permEntry.mType),
+                         permEntry.mPermission,
+                         permEntry.mExpireType,
+                         permEntry.mExpireTime));
+    }
+  }
+
+  return NS_NewArrayEnumerator(aEnum, array);
+}
+
 NS_IMETHODIMP nsPermissionManager::Observe(nsISupports *aSubject, const char *aTopic, const char16_t *someData)
 {
   ENSURE_NOT_CHILD_PROCESS;
diff --git a/netwerk/base/nsIPermissionManager.idl b/netwerk/base/nsIPermissionManager.idl
index 5e4c630bbd79..58a4810b7f11 100644
--- a/netwerk/base/nsIPermissionManager.idl
+++ b/netwerk/base/nsIPermissionManager.idl
@@ -93,6 +93,15 @@ interface nsIPermissionManager : nsISupports
            [optional] in uint32_t expireType,
            [optional] in int64_t expireTime);
 
+  /**
+   * Get all custom permissions for a given URI. This will return
+   * an enumerator of all permissions which are not set to default
+   * and which belong to the matching prinicpal of the given URI.
+   *
+   * @param uri  the URI to get all permissions for
+   */
+  nsISimpleEnumerator getAllForURI(in nsIURI uri);
+
   /**
    * Add permission information for a given principal.
    * It is internally calling the other add() method using the nsIURI from the