[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).
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