Re: Wiretapping Linux?

From: Jan Engelhardt
Date: Wed May 17 2006 - 14:46:36 EST

>> > A pci device can read system RAM and other memory-mapped PCI devices
>> > (such as display framebuffers) using DMA. In addition, a pci (but not
>> > pci-express) device can snoop on pci bus traffic to other devices.
>> > Typically, however, hard drive controllers will be integrated into the
>> > chipset so the data is not on the bus.
>> Thanks for providing this information. This makes the binary firmware
>> required for peripherals even more interesting for security conscious
>> people.
> Note that some machines have IOMMUs so it may be possible to prevent a device
> from reading main memory, perhaps at a performance cost.
> My AMD machine disables the IOMMU on startup.
> If you don't trust your hardware there are only two solutions: keep it off the
> net or keep it off.

It gets even more complex with remote management solutions, ranging from
simple PCI boards that can reset the machine to fully-integrated [like
Sun's RSC] processors that can poke anything.

Jan Engelhardt
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