linux-kernel - Re: [PATCH 0/4] KEYS: validate key trust with owner and builtin keys only

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Date:	Tue, 10 Jun 2014 08:52:30 -0400
From:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
To:	Josh Boyer <jwboyer@...hat.com>
Cc:	Dmitry Kasatkin <d.kasatkin@...sung.com>, dhowells@...hat.com,
	keyrings@...ux-nfs.org, linux-security-module@...r.kernel.org,
	linux-kernel@...r.kernel.org, dmitry.kasatkin@...il.com,
	mjg59@...f.ucam.org
Subject: Re: [PATCH 0/4] KEYS: validate key trust with owner and builtin
 keys only

On Tue, 2014-06-10 at 08:20 -0400, Josh Boyer wrote: 
> On Tue, Jun 10, 2014 at 11:48:14AM +0300, Dmitry Kasatkin wrote:

> > Also I want to discuss here Fedora UEFI patches as they are the reason for
> > the these original patchset.
> > 
> > http://pkgs.fedoraproject.org/cgit/kernel.git/tree/modsign-uefi.patch
> > 
> > They provide functionality to specify MokIgnoreDb variable to limit loading of
> > UEFI keys only from MOK List, while ignoring DB. This is certainly a good
> > functionality. But once MODULE_SIG_UEFI is enabled, it looks there is no way
> > to prevent loading keys from UEFI at all. And this might not be a good default
> > functionality. Someone might want not allow loading of keys from UEFI unless
> > kernel parameter is specified to allow it without recompiling the kernel
> > and disabling MODULE_SIG_UEFI.
> > 
> > Josh, why such design decision was made?
> 
> IIRC, it's because kernel parameters can be added programmatically from a
> remote user if they gain root access.  Having a kernel parameter to
> disable a key piece of secure boot isn't all that great.  We disable
> other kernel parameters like acpi_rspd as well.

In this case, there shouldn't be a problem as the kernel parameters
would further limit the keys usage.

Mimi

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