linux-kernel - Re: [GIT PULL] Load keys from signed PE binaries

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Date:	Fri, 1 Mar 2013 00:52:51 +0100 (CET)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Matthew Garrett <mjg59@...f.ucam.org>
Cc:	David Howells <dhowells@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	jwboyer@...hat.com, pjones@...hat.com, vgoyal@...hat.com,
	keescook@...omium.org, keyrings@...ux-nfs.org,
	linux-kernel@...r.kernel.org, Greg KH <gregkh@...uxfoundation.org>,
	Florian Weimer <fw@...eb.enyo.de>,
	Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [GIT PULL] Load keys from signed PE binaries

On Thu, 28 Feb 2013, Matthew Garrett wrote:

> > > Sure, if you've been infected before the revocation, you'll still be 
> > > infected. There's not really any good way around that.
> > 
> > Which is a very substantial difference to normal X509 chain of trust, 
> > isn't it?
> 
> If you've loaded an x.509 certificate into the kernel and it's later 
> revoked, any module signed with the key is going to be loadable until 
> it's revoked. I don't see an especially large difference here?

i_own_your_ring0.ko can be modprobed long after blacklisting of "hello 
world" binary hash has happened on the very particular machine in its dbx 
(as there is no link, in a x509-chain-of-trust-sense, between the hash of 
the PE binary and the i_own_your_ring0.ko signature key).

modprobe of a module signed by a key that has been blacklisted on the very 
particular machine in its dbx is not going to work (as there is a very 
direct x509 chain of trust link).

No?

Thanks,

-- 
Jiri Kosina
SUSE Labs
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