Re: [RFC][PATCH 0a/3] TXT: Intel(R) Trusted Execution Technologysupport for Linux - Overview

[Pavel Machek <pavel@suse.cz>]

> > > > You exit/reenter the trusted mode accross sleep... so any
> guarantees
> > > > "trusted" mode does are void, right?
> > >
> > > You exit from kernel to tboot on any shutdown, which handles the
> proper
> > > teardown of the measured env (meaning you also come back on via
> tboot).
> > > So things like saving tpm state, scrubbing secrets from memory, etc.
> > 
> > Aha, so instead sleep mode is useless because I'll have to remount all
> > the crypto filesystems and restart all the apps...
> 
> Sleep mode works the same as it does today (caveat S4 issue which we
> will fix), it just goes through the tboot code before putting the
> platform HW into the appropriate state.  What this process is adding is
> that on resume, tboot will get control from BIOS instead of the kernel.
> Then tboot will re-launch the TXT environment before going back to the
> kernel at the kernel's expected S3 resume vector.  The re-establishing
> of the protected environment won't disrupt the subsequent kernel resume
> process.

No, I don't get it. So presumably useful thing to do is to seal my
crypto partition so that only known-good kernel can access it?

But then, the crypto keys will be in ram during suspend/resume
(because I have the filesystem mounted) => I loose any guarantees?

								Pavel
-- 
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