linux-kernel - Re: [RFD] linux-firmware key arrangement for firmware signing

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Date:	Wed, 20 May 2015 16:35:51 -0400
From:	Kyle McMartin <jkkm@...m.org>
To:	Seth Forshee <seth.forshee@...onical.com>
Cc:	"Luis R. Rodriguez" <mcgrof@...e.com>,
	linux-security-module@...r.kernel.org, james.l.morris@...cle.com,
	serge@...lyn.com, linux-kernel@...r.kernel.org,
	linux-wireless@...r.kernel.org,
	David Howells <dhowells@...hat.com>,
	David Woodhouse <david.woodhouse@...el.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Joey Lee <jlee@...e.de>, Rusty Russell <rusty@...tcorp.com.au>,
	zohar@...ux.vnet.ibm.com, mricon@...nel.org
Subject: Re: [RFD] linux-firmware key arrangement for firmware signing

On Wed, May 20, 2015 at 09:04:26AM -0500, Seth Forshee wrote:
> I raised the question of key revocation when we discussed this on irc,
> but it wasn't answered to my satisfaction. If a key signed by the
> kernel-embedded key is compromised, how can that key be revoked so that
> it is no longer trusted?
> 
> Someone mentioned UEFI blacklists, which I don't know much about, but
> not all systems have UEFI. The only reliable option that comes to mind
> for me is an in-kernel blacklist of keys which should no longer be
> trusted.
> 

I think the solution here is two-fold... first, we'll probably try some
to use a HSM for signing, so there's extremely low risk of compromise.
Secondly, if we annotate the key such that it can only be used for
firmware, a compromise of my key won't allow you to kexec or load kernel
modules.

regards, --Kyle
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