Messages in this thread |  | | | From | Roland Dreier <> | | Subject | Re: [GIT PULL] x86/txt for v2.6.32 | | Date | Sat, 03 Oct 2009 13:44:22 -0700 |
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> > > So I modify the RAM content so that BIOS does not think measured > > > environment existed before suspend?
> And it is ridiculously easy to pull off, too: > http://www.engadget.com/2008/02/21/cold-boot-disk-encryption-attack-is-shockingly-effective/ > > Shows the attack being used to read sensitive keys, but you can use it also > to *modify* system running state (it will be more difficult, as you need to > remove and replace the RAM while on S3 instead of S5, but it should be > doable by someone who knows what he is doing).
I believe the whole point of this TXT / S3 handling is that the resume from S3 will then be able to detect that the contents of RAM have been modified while the system was asleep.
TXT simply produces a reasonably trustworthy measurement of system state. If you modify RAM while the system is asleep, then you will not be able to produce a measurement showing an unmodified system state.
- R.
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