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Date: Fri, 23 Feb 2024 10:30:04 -0800
From: Eric Biggers <ebiggers@kernel.org>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Ard Biesheuvel <ardb@kernel.org>,
	Ross Philipson <ross.philipson@oracle.com>,
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Subject: Re: [PATCH v8 06/15] x86: Add early SHA support for Secure Launch
 early measurements
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In-Reply-To: <e641e2f1-16cf-4717-8a1f-8afac2644efe@citrix.com>

On Fri, Feb 23, 2024 at 06:20:27PM +0000, Andrew Cooper wrote:
> On 23/02/2024 5:54 pm, Eric Biggers wrote:
> > On Fri, Feb 23, 2024 at 04:42:11PM +0000, Andrew Cooper wrote:
> >> Yes, and I agree.? We're not looking to try and force this in with
> >> underhand tactics.
> >>
> >> But a blind "nack to any SHA-1" is similarly damaging in the opposite
> >> direction.
> >>
> > Well, reviewers have said they'd prefer that SHA-1 not be included and given
> > some thoughtful reasons for that.  But also they've given suggestions on how to
> > make the SHA-1 support more palatable, such as splitting it into a separate
> > patch and giving it a proper justification.
> >
> > All suggestions have been ignored.
> 
> The public record demonstrates otherwise.
> 
> But are you saying that you'd be happy if the commit message read
> something more like:
> 
> ---8<---
> For better or worse, Secure Launch needs SHA-1 and SHA-256.
> 
> The choice of hashes used lie with the platform firmware, not with
> software, and is often outside of the users control.
> 
> Even if we'd prefer to use SHA-256-only, if firmware elected to start us
> with the SHA-1 and SHA-256 backs active, we still need SHA-1 to parse
> the TPM event log thus far, and deliberately cap the SHA-1 PCRs in order
> to safely use SHA-256 for everything else.
> ---

Please take some time to read through the comments that reviewers have left on
previous versions of the patchset.

- Eric