gentoo-overlay/net-misc/networkmanager/files/01-org.freedesktop.NetworkManager.settings.modify.system.rules

// Let users in plugdev group modify NetworkManager
polkit.addRule(function(action, subject) {
    if (action.id == "org.freedesktop.NetworkManager.settings.modify.system" &&
        subject.isInGroup("plugdev") && subject.active) {
        return "yes";
    }
});