Messages in this thread | | | Date | Tue, 29 Sep 2009 19:13:18 +0200 | From | Pavel Machek <> | Subject | Re: [GIT PULL] x86/txt for v2.6.32 |
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On Tue 2009-09-29 14:34:09, Shane Wang wrote: > Pavel Machek wrote: >> On Mon 2009-09-28 14:11:25, H. Peter Anvin wrote: >>> On 09/28/2009 02:07 PM, Rafael J. Wysocki wrote: >>>>> Well, I worry that S3 support for TXT makes TXT completely useless. A >>>>> little liquid nitrogen, remove RAM, place it in another machine, >>>>> modify it in any way you want, more liquid nitrogen, place it back. >>>>> >>>>> Oops, protection provided by TXT is lost. >>>> Ah, I see your point now. >>>> >>> Shane Wang sent me a patch for S3 support, but it missed the merge window: >>> >>> http://marc.info/?i=4A9CE0B2.5060608@intel.com >>> >>> *As far as I understand* -- and I haven't looked into it in detail yet, >>> having just come back from Plumber's -- this provides integrity >>> protection, not content extraction protection.
Well, documentation seems to suggest it provides content protection, too. If not, should that be clearly documented in Doc*/intel_txt? [Also, I'd expect threat model aka "what does it protect against there"].
>> How does it provide integrity protection? I'm free to modify RAM >> content in the other machine....
> > Before S3 sleep, tboot patch will MAC the memory, and after S3 resume, > the memory integrity will be verified according to the MAC value. So, you > can't modify RAM, or else you will fail on S3 resume. > > The current patch hpa mentioned is for userspace memory integrity. For > kernel memory integrity, the code is already in with the previous txt > patch.
Ok, and what prevents me from commenting out the MAC checking code?
Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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