wpa_supplicant/dbus/dbus-wpa_supplicant.conf

<!DOCTYPE busconfig PUBLIC
 "-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN"
 "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
<busconfig>
        <policy user="root">
                <allow own="fi.w1.wpa_supplicant1"/>

                <allow send_destination="fi.w1.wpa_supplicant1"/>
                <allow send_interface="fi.w1.wpa_supplicant1"/>
                <allow receive_sender="fi.w1.wpa_supplicant1" receive_type="signal"/>
        </policy>
        <policy context="default">
                <deny own="fi.w1.wpa_supplicant1"/>
                <deny send_destination="fi.w1.wpa_supplicant1"/>
                <deny receive_sender="fi.w1.wpa_supplicant1" receive_type="signal"/>
        </policy>
</busconfig>