linux-kernel - Re: EFI and multiboot2 devlopment work for Xen

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Message-Id: <5266422B02000078000FC98E@nat28.tlf.novell.com>
Date:	Tue, 22 Oct 2013 08:15:23 +0100
From:	"Jan Beulich" <JBeulich@...e.com>
To:	"Daniel Kiper" <daniel.kiper@...cle.com>
Cc:	<ian.campbell@...rix.com>, <ross.philipson@...rix.com>,
	<stefano.stabellini@...citrix.com>, <grub-devel@....org>,
	<david.woodhouse@...el.com>, <richard.l.maliszewski@...el.com>,
	"xen-devel" <xen-devel@...ts.xenproject.org>,
	<boris.ostrovsky@...cle.com>, <konrad.wilk@...cle.com>,
	<pjones@...hat.com>, <linux-kernel@...r.kernel.org>, <keir@....org>
Subject: Re: EFI and multiboot2 devlopment work for Xen

>>> On 21.10.13 at 20:39, Daniel Kiper <daniel.kiper@...cle.com> wrote:
> On Mon, Oct 21, 2013 at 02:36:38PM +0100, Jan Beulich wrote:
>> >>> On 21.10.13 at 14:57, Daniel Kiper <daniel.kiper@...cle.com> wrote:
>> > Separate multiboot2efi module should be established. It should verify system
>> > kernel and all loaded modules using shim on EFI platforms with enabled
>> > secure boot
>>
>> Each involved component verifies only the next image. I.e. the
>> shim verifies the Xen image, and Xen verifies the Dom0 kernel
>> binary. The Dom0 kernel (assuming it to be Linux) will then be
>> responsible for dealing with its initrd. (One open question is how
> 
> Currently Linux Kernel is only verified. Sorry, my fault.
> As I know Matthew Garrett would like to verify Linux Kernel
> modules too. However, I do not know details now. I think that
> we should take into account his work.

Sure, Linux modules are to be verified. But that's a Linux thing
we can be entirely unconcerned about. In the context of GrUB,
"module" can only have the meaning of GrUB modules.

>> Xen ought to deal with an eventual XSM module; I take it that
> 
> Could you tell me more about that? What issues do you expect here?

We obviously need to have a way to verify the integrity of an
XSM module. Otherwise - as with any unverified component -
its presence would break the integrity of the supposedly secure
system.

Jan

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