linux-kernel - Re: [PATCH 0/6] Intel Secure Guard Extensions

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Date:	Tue, 26 Apr 2016 21:41:17 +0200
From:	Pavel Machek <pavel@....cz>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
	Greg KH <gregkh@...uxfoundation.org>,
	Andy Lutomirski <luto@...nel.org>,
	Borislav Petkov <bp@...e.de>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	"open list:STAGING SUBSYSTEM" <devel@...verdev.osuosl.org>,
	Ingo Molnar <mingo@...nel.org>,
	Kristen Carlson Accardi <kristen@...ux.intel.com>,
	"open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
	open list <linux-kernel@...r.kernel.org>,
	Mathias Krause <minipli@...glemail.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Wan Zongshun <Vincent.Wan@....com>
Subject: Re: [PATCH 0/6] Intel Secure Guard Extensions

On Tue 2016-04-26 12:05:48, Andy Lutomirski wrote:
> On Tue, Apr 26, 2016 at 12:00 PM, Pavel Machek <pavel@....cz> wrote:
> > On Mon 2016-04-25 20:34:07, Jarkko Sakkinen wrote:
> >> Intel(R) SGX is a set of CPU instructions that can be used by
> >> applications to set aside private regions of code and data.  The code
> >> outside the enclave is disallowed to access the memory inside the
> >> enclave by the CPU access control.
> >>
> >> The firmware uses PRMRR registers to reserve an area of physical memory
> >> called Enclave Page Cache (EPC). There is a hardware unit in the
> >> processor called Memory Encryption Engine. The MEE encrypts and decrypts
> >> the EPC pages as they enter and leave the processor package.
> >
> > What are non-evil use cases for this?
> 
> Storing your ssh private key encrypted such that even someone who
> completely compromises your system can't get the actual private key

Well, if someone gets root on my system, he can get my ssh private
key.... right?

So, you can use this to prevent "cold boot" attacks? (You know,
stealing machine, liquid nitrogen, moving DIMMs to different machine
to read them?) Ok. That's non-evil.

Is there reason not to enable this for whole RAM if the hw can do it? 

> out.  Using this in conjunction with an RPMB device to make it Rather
> Difficult (tm) for third parties to decrypt your disk even if you
> password has low entropy.  There are plenty more.

I'm not sure what RPMB is, but I don't think you can make it too hard
to decrypt my disk if my password has low entropy. ... And I don't see
how encrypting RAM helps there.

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