[coreboot] dealing with a malicious OS

Jonathan M. McCune jonmccune at cmu.edu
Fri Apr 18 18:07:00 CEST 2008


I'm interested in trying to capture keyboard events by causing them to
generate SMIs, and then writing my own handler for the SMIs.  This is
for a research project on trusted path mechanisms, so it may seem a
little strange.  Please bear with me. :-)

I'm hoping somebody on this mailing list can offer some advice.

The approach I am considering uses USB support for legacy operating
systems, where USB-related interrupts can be diverted to SMI.
Typically, they are handled by the BIOS.  I would modify coreboot to
implement the necessary handler.  There is a well-defined protocol for
handing off control from the BIOS to a USB-aware OS driver, and I would
write my code such that it will perform this handoff only under certain

However, I am concerned about a malicious OS simply trampling on the USB
controller (via its memory-mapped and/or PCI space interfaces).

More information about the coreboot mailing list