On Tue, Nov 20, 2018 at 09:25:43AM -0800, James Bottomley wrote: > On Tue, 2018-11-20 at 14:41 +0200, Jarkko Sakkinen wrote: > > On Tue, Nov 20, 2018 at 01:10:49PM +0200, Jarkko Sakkinen wrote: > > > This is basically rewrite of TPM genie paper with extras. Maybe > > > just shorten it to include the proposed architecture and point to > > > the TPM Genie paper (which is not in the references at all ATM). > > > > > > The way I see it the data validation is way more important than > > > protecting against physical interposer to be frank. > > > > > > The attack scenario would require to open the damn device. For > > > laptop that would leave physical marks (i.e. evil maid). In a data > > > center with armed guards I would wish you good luck accomplishing > > > it. It is not anything like sticking a USB stick and run. > > > > > > We can take a fix into Linux with a clean implementation but it > > > needs to be an opt-in feature because not all users will want to > > > use it. > > > > Someone (might have been either Mimi or David Howells but cannot > > recall) correctly pointed out at LSS 2018 that you could just as > > easily spy and corrupt RAM if you have a time window to perform this > > type of attack. > > Not using the simple plug in on the TPM bus, you can't. The point is > basically the difference in the technology: the interposer is a simple, > easy to construct, plugin; a RAM spy is a huge JTAG thing that would be > hard even to fit into a modern thin laptop, let alone extremely > difficult to build. Why you wouldn't use DMA to spy the RAM? /Jarkko
