From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Howells <dhowells@redhat.com>
Subject: Re: [PATCH 5/7] efi: Get the secure boot status [ver #3]
Date: Fri, 25 Nov 2016 12:35:03 +0000
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To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: James Bottomley <James.Bottomley@hansenpartnership.com>, "linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, dhowells@redhat.com, linux-security-module <linux-security-module@vger.kernel.org>, Lukas Wunner <lukas@wunner.de>, keyrings@vger.kernel.org, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>
List-Id: linux-efi@vger.kernel.org

Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:

> Yes. In pre-2.6, DeployedMode is not a reserved name, and so it may be
> possible for someone to slip in a DeployedMode=0 on a secure boot
> enabled system to trick the kernel into thinking lockdown should be
> disabled.

How does one get the version number?  Unfortunately, searching the document
for 'version' doesn't help as every page has that in the footer:-/

> > +               if (val == 1)
> > +                       return 0;
> 
> I think the logic is the wrong way around here. Secure Boot is enabled
> if SecureBoot=1 and SetupMode=0, unless DeployedMode=0. So you should
> return 0 here if val == 0, but only when running on 2.6 or later.

Good point.

David