Controlled hardware access under Pentium based Linux & FreeBSD

Abstract

Pentium class processors have a very flexible hardware security system but common operating systems fail to take full advantage of this flexibility. This paper examines how hardware access is controlled under Microsoft Windows, Linux and FreeBSD and concludes that user space access to hardware IO ports is inadequate, either non-existent or implemented in such a way as to be insecure. A simple, novel method is then proposed that allows user level programs to access hardware in a tightly controlled manner under Linux and FreeBSD. This has particular application to computer based control systems and the development of device drivers from within user space. It also facilitates secure and tightly controlled access to hardware IO in the educational environment.