You can dual-license if you own the full copyright ownership but if you include GPLed stuff (and don't have the full copyright ownership) you'll have to GPL the

You can dual-license if you own the full copyright ownership but if you include GPLed stuff (and don't have the full copyright ownership) you'll have to GPL the result. As for "at least as permissive" - it requires no further restrictions, but it adds a bunch of restrictions itself. And there's no other license that doesn't add restrictions - MIT adds restrictions to reproduce the MIT license, which is an extra restriction. The restrictions are attempted excused by the FSF under the "attribution" clause of the GPL, but it is not clear to me that is valid and it has not tested by any court.