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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
Date: Tue, 19 Mar 2013 18:50:03 +0000	[thread overview]
Message-ID: <20130319185003.GA13301@srcf.ucam.org> (raw)
In-Reply-To: <1363718456.2377.71.camel@dabdike.int.hansenpartnership.com>

On Tue, Mar 19, 2013 at 06:40:56PM +0000, James Bottomley wrote:
> On Tue, 2013-03-19 at 18:28 +0000, Matthew Garrett wrote:
> > 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.
> 
> It requires the *public* key to survive power down, certainly.  The
> private key can be thrown away once the hibernate image is signed.  I
> think the scheme can be constructed so the private key is never in NV
> storage ... that also makes it more secure against tampering.

Well, that somewhat complicates implementation - we'd be encrypting the 
entire contents of memory except for the key that we're using to encrypt 
memory. Keeping the public key away from userspace avoids having to care 
about that.

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

WARNING: multiple messages have this Message-ID (diff)
From: Matthew Garrett <mjg59-1xO5oi07KQx4cg9Nei1l7Q@public.gmane.org>
To: James Bottomley
	<James.Bottomley-d9PhHud1JfjCXq6kfMZ53/egYHeGw8Jk@public.gmane.org>
Cc: linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-kernel
	<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [PATCH] x86/efi: pull NV+BS variables out before we exit boot services
Date: Tue, 19 Mar 2013 18:50:03 +0000	[thread overview]
Message-ID: <20130319185003.GA13301@srcf.ucam.org> (raw)
In-Reply-To: <1363718456.2377.71.camel-sFMDBYUN5F8GjUHQrlYNx2Wm91YjaHnnhRte9Li2A+AAvxtiuMwx3w@public.gmane.org>

On Tue, Mar 19, 2013 at 06:40:56PM +0000, James Bottomley wrote:
> On Tue, 2013-03-19 at 18:28 +0000, Matthew Garrett wrote:
> > 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.
> 
> It requires the *public* key to survive power down, certainly.  The
> private key can be thrown away once the hibernate image is signed.  I
> think the scheme can be constructed so the private key is never in NV
> storage ... that also makes it more secure against tampering.

Well, that somewhat complicates implementation - we'd be encrypting the 
entire contents of memory except for the key that we're using to encrypt 
memory. Keeping the public key away from userspace avoids having to care 
about that.

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

  reply	other threads:[~2013-03-19 18:50 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-18  8:40 [PATCH] x86/efi: pull NV+BS variables out before we exit boot services James Bottomley
2013-03-18  8:40 ` James Bottomley
2013-03-19  1:48 ` Matthew Garrett
2013-03-19  1:48   ` Matthew Garrett
2013-03-19  8:14   ` James Bottomley
2013-03-19  8:14     ` James Bottomley
2013-03-19 16:35     ` Matthew Garrett
2013-03-19 16:35       ` Matthew Garrett
2013-03-19 17:17       ` James Bottomley
2013-03-19 17:25         ` Matthew Garrett
2013-03-19 17:25           ` Matthew Garrett
2013-03-19 18:23           ` James Bottomley
2013-03-19 18:23             ` James Bottomley
2013-03-19 18:28             ` Matthew Garrett
2013-03-19 18:28               ` Matthew Garrett
2013-03-19 18:40               ` James Bottomley
2013-03-19 18:40                 ` James Bottomley
2013-03-19 18:50                 ` Matthew Garrett [this message]
2013-03-19 18:50                   ` Matthew Garrett
2013-03-19 23:00                   ` James Bottomley
2013-03-19 23:00                     ` James Bottomley
2013-03-19 23:17                     ` Matthew Garrett
2013-03-19 23:17                       ` Matthew Garrett
2013-03-20  8:00                       ` James Bottomley
2013-03-20  8:00                         ` James Bottomley
2013-03-20 11:47                         ` Matthew Garrett
2013-03-20 11:47                           ` Matthew Garrett
2013-03-20 11:26 ` Matt Fleming
2013-03-20 11:26   ` Matt Fleming

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