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Date: Tue, 19 Mar 2013 18:28:10 +0000
From: Matthew Garrett <mjg59@srcf.ucam.org>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: linux-efi@vger.kernel.org, linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86/efi: pull NV+BS variables out before we exit boot
 services
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On Tue, Mar 19, 2013 at 06:23:31PM +0000, James Bottomley wrote:

> The scheme we discussed, unless something radically changed, was to
> convey a temporary key pair via a mechanism to later verify the
> hybernate kernel on a resume.  That only requires reboot safe knowledge
> of the public key.  The private key can be conveyed in BS only (not NV),
> and should be consumed (as in deleted) by the OS when it receives it, so
> it wouldn't be exposed by this patch.

It requires the key to survive the system being entirely powered down, 
which means it needs to be BS+NV. It shouldn't be possible for userspace 
to access this key.

-- 
Matthew Garrett | mjg59@srcf.ucam.org

From mboxrd@z Thu Jan  1 00:00:00 1970
From: Matthew Garrett <mjg59-1xO5oi07KQx4cg9Nei1l7Q@public.gmane.org>
Subject: Re: [PATCH] x86/efi: pull NV+BS variables out before we exit boot
 services
Date: Tue, 19 Mar 2013 18:28:10 +0000
Message-ID: <20130319182810.GA13003@srcf.ucam.org>
References: <1363596014.2412.8.camel@dabdike.int.hansenpartnership.com>
 <20130319014850.GA28934@srcf.ucam.org>
 <1363680885.2377.11.camel@dabdike.int.hansenpartnership.com>
 <20130319163531.GA10879@srcf.ucam.org>
 <1363713447.2377.60.camel@dabdike.int.hansenpartnership.com>
 <20130319172506.GA11969@srcf.ucam.org>
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On Tue, Mar 19, 2013 at 06:23:31PM +0000, James Bottomley wrote:

> The scheme we discussed, unless something radically changed, was to
> convey a temporary key pair via a mechanism to later verify the
> hybernate kernel on a resume.  That only requires reboot safe knowledge
> of the public key.  The private key can be conveyed in BS only (not NV),
> and should be consumed (as in deleted) by the OS when it receives it, so
> it wouldn't be exposed by this patch.

It requires the key to survive the system being entirely powered down, 
which means it needs to be BS+NV. It shouldn't be possible for userspace 
to access this key.

-- 
Matthew Garrett | mjg59-1xO5oi07KQx4cg9Nei1l7Q@public.gmane.org