/usr/include/solid/control/ifaces/ is in kde-workspace-dev 4:4.8.5-0ubuntu0.4.
This file is owned by root:root, with mode 0o755.
..
/usr/include/solid/control/ifaces/modemcdmainterface.h
/usr/include/solid/control/ifaces/modemgsmcardinterface.h
/usr/include/solid/control/ifaces/modemgsmcontactsinterface.h
/usr/include/solid/control/ifaces/modemgsmhsointerface.h
/usr/include/solid/control/ifaces/modemgsmnetworkinterface.h
/usr/include/solid/control/ifaces/modemgsmsmsinterface.h
/usr/include/solid/control/ifaces/modemgsmussdinterface.h
/usr/include/solid/control/ifaces/modeminterface.h
/usr/include/solid/control/ifaces/modemlocationinterface.h
/usr/include/solid/control/ifaces/modemmanager.h
/usr/include/solid/control/ifaces/networkbtinterface.h
/usr/include/solid/control/ifaces/networkcdmainterface.h
/usr/include/solid/control/ifaces/networkgsminterface.h
/usr/include/solid/control/ifaces/networkinterface.h
/usr/include/solid/control/ifaces/networkmanager.h
/usr/include/solid/control/ifaces/networkserialinterface.h
/usr/include/solid/control/ifaces/wirednetworkinterface.h
/usr/include/solid/control/ifaces/wirelessaccesspoint.h
/usr/include/solid/control/ifaces/wirelessnetworkinterface.h