--- a/extensions/cookie/nsPermissionManager.cpp
+++ b/extensions/cookie/nsPermissionManager.cpp
@@ -2240,16 +2240,46 @@ NS_IMETHODIMP nsPermissionManager::GetEn
                          permEntry.mExpireType,
                          permEntry.mExpireTime));
     }
   }
 
   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;
 
   if (!nsCRT::strcmp(aTopic, "profile-before-change")) {
     // The profile is about to change,
     // or is going away because the application is shutting down.
     mIsShuttingDown = true;

--- a/netwerk/base/nsIPermissionManager.idl
+++ b/netwerk/base/nsIPermissionManager.idl
@@ -89,16 +89,25 @@ interface nsIPermissionManager : nsISupp
    */
   void add(in nsIURI uri,
            in string type,
            in uint32_t permission,
            [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
    * principal.
    * Passing a system principal will be a no-op because they will always be
    * granted permissions.
    */
   void addFromPrincipal(in nsIPrincipal principal, in string typed,
                         in uint32_t permission,