Re: [PATCH 0/5 v2][RFC] Encryption and authentication for hibernate snapshot image

Pavel Machek
2019-01-08T23:42:51Z

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Hi!

> >> Please explain your security goals.
> >
> > My security goals:
> >
> > - Encrypt and authicate hibernate snapshot image in kernel space. Userspace
> > can only touch an encrypted and signed snapshot image.
>
> Signed?
>
> I’m not entirely convinced that the keyring mechanism is what you
> want. ISTM that there are two goals here:
>
> a) Encryption: it should be as hard as can reasonably be arranged to
> extract secrets from a hibernation image.
>
> b) Authentication part 1: it should not be possible for someone in
> possession of a turned-off machine to tamper with the hibernation
> image such that the image, when booted, will leak its secrets. This
> should protect against attackers who don’t know the encryption key.
>
> c) Authentication part 2: it should be to verify, to the extent
> practical, that the image came from the same machine and was really
> created using hibernation. Or maybe by the same user.

So... this looks like "security goals" I was asking in the first
place. Thanks!

Could we get something like that (with your real goals?) in the next
version of the patch?

> As far as I can tell, there is only one reason that any of this needs
> to be in the kernel: if it’s all in user code, then we lose “lockdown”
> protection against compromised user code on a secure boot system. Is
> that, in fact, true?

And this is what I'd really like answer to. Because... I'd really like
this to be in userspace if it does not provide additional security
guarantees.

Thanks,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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