Re: [PATCH 1/7] multiboot2: Add load type header and support for the PE binary type

From: Jan Beulich <jbeulich@suse.com>
To: Ross Lagerwall <ross.lagerwall@citrix.com>
Cc: xen-devel@lists.xenproject.org,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Daniel Kiper <daniel.kiper@oracle.com>,
	grub-devel@gnu.org
Subject: Re: [PATCH 1/7] multiboot2: Add load type header and support for the PE binary type
Date: Thu, 14 Mar 2024 14:37:37 +0100	[thread overview]
Message-ID: <d2be3727-3a94-408f-a751-e91792c9d15c@suse.com> (raw)
In-Reply-To: <CAG7k0Ep6fDfjKXj-iwuGh=pF_BS-1EaT9kRm1xJTZ=bmt=3+rA@mail.gmail.com>

On 14.03.2024 10:30, Ross Lagerwall wrote:
> On Thu, Mar 14, 2024 at 7:24 AM Jan Beulich <jbeulich@suse.com> wrote:
>>
>> On 13.03.2024 16:07, Ross Lagerwall wrote:
>>> In addition to the existing address and ELF load types, specify a new
>>> optional PE binary load type. This new type is a useful addition since
>>> PE binaries can be signed and verified (i.e. used with Secure Boot).
>>
>> And the consideration to have ELF signable (by whatever extension to
>> the ELF spec) went nowhere?
>>
> 
> I'm not sure if you're referring to some ongoing work to create signable
> ELFs that I'm not aware of.

Something must have been invented already to make Linux modules signable.

> I didn't choose that route because:
> 
> * Signed PE binaries are the current standard for Secure Boot.
> 
> * Having signed ELF binaries would mean that code to handle them needs
> to be added to Shim which contravenes its goals of being small and
> simple to verify.

Both true, but neither goes entirely without saying, I suppose.

> * I could be wrong on this but to my knowledge, the ELF format is not
> being actively updated nor is the standard owned/maintained by a
> specific group which makes updating it difficult.

And PE/COFF isn't under control of a public entity / group afaik, which
may be viewed as no better, if not worse.

> * Tools would need to be updated/developed to add support for signing
> ELF binaries and inspecting the signatures.

As above, yes indeed.

Jan