Re: [RFC PATCH] x86: Config options to assign versions in the PE-COFF header

From: Gary Lin <glin@suse.com>
To: hpa@zytor.com
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	linux-efi@vger.kernel.org,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Michal Marek <mmarek@suse.com>,
	Matt Fleming <matt@codeblueprint.co.uk>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Joey Lee <jlee@suse.com>, Vojtech Pavlik <vojtech@suse.cz>
Subject: Re: [RFC PATCH] x86: Config options to assign versions in the PE-COFF header
Date: Fri, 14 Apr 2017 11:51:19 +0800	[thread overview]
Message-ID: <20170414035119.v2kjxcsuauj3bdj2@GaryWorkstation> (raw)
In-Reply-To: <8E544119-66B8-4482-BBE9-68B6C7A3AAE9@zytor.com>

On Thu, Apr 13, 2017 at 03:21:20PM -0700, hpa@zytor.com wrote:
> On April 11, 2017 3:20:41 AM PDT, Gary Lin <glin@suse.com> wrote:
> >This commit adds the new config options to allow the user to modify the
> >following fields in the PE-COFF header.
> >
> >UINT16 MajorOperatingSystemVersion
> >UINT16 MinorOperatingSystemVersion
> >UINT16 MajorImageVersion
> >UINT16 MinorImageVersion
> >
> >Those fields are mainly for the executables or libraries in Windows NT
> >or higher to specify the minimum supported Windows version and the
> >version of the image itself.
> >
> >Given the fact that those fields are ignored in UEFI, we can safely
> >reuse
> >those fields for other purposes, e.g. Security Version(*).
> >
> >(*) https://github.com/lcp/shim/wiki/Security-Version
> >
> >Cc: Thomas Gleixner <tglx@linutronix.de>
> >Cc: Ingo Molnar <mingo@redhat.com>
> >Cc: "H. Peter Anvin" <hpa@zytor.com>
> >Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
> >Cc: Michal Marek <mmarek@suse.com>
> >Cc: Matt Fleming <matt@codeblueprint.co.uk>
> >Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> >Cc: Joey Lee <jlee@suse.com>
> >Cc: Vojtech Pavlik <vojtech@suse.cz>
> >Signed-off-by: Gary Lin <glin@suse.com>
> >Tested-by: Joey Lee <jlee@suse.com>
> >---
[snip]
> 
> Reusing PECOFF fields seems doubleplusunsafe: we don't own those fields, the UEFI forum does.  It would make a lot more sense to add these fields to the bzImage header directly or indirectly (via a pointer), the latter would be more economical since the bzImage header size is bounded.
> 
> We could even define it as a pointer to a "security information header" with its own size field, so it can be grown in the future as needed.
Reusing PE-COFF simplifies the implementation since shim can parse the
header directly. I can raise the issue to the UEFI forum to clarify the
usage of those fields.

Meanwhile, I'll also look into the bzImage header in case the PE-COFF
header is really a NO-GO.

Thanks,

Gary Lin