linux-kernel - Re: [PATCH 3/3] x86/ima: retry detecting secure boot mode

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Date:   Thu, 07 Mar 2019 17:48:17 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Matthew Garrett <mjg59@...gle.com>,
        Justin Forbes <jforbes@...hat.com>
Cc:     linux-integrity <linux-integrity@...r.kernel.org>,
        LSM List <linux-security-module@...r.kernel.org>,
        linux-efi <linux-efi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        David Howells <dhowells@...hat.com>,
        Seth Forshee <seth.forshee@...onical.com>,
        kexec@...ts.infradead.org, Nayna Jain <nayna@...ux.ibm.com>
Subject: Re: [PATCH 3/3] x86/ima: retry detecting secure boot mode

On Thu, 2019-03-07 at 14:44 -0800, Matthew Garrett wrote:
> On Thu, Mar 7, 2019 at 2:38 PM Justin Forbes <jforbes@...hat.com> wrote:
> > On Thu, Mar 7, 2019 at 4:29 PM Matthew Garrett <mjg59@...gle.com> wrote:
> >>
> >> On Mon, Nov 19, 2018 at 11:57 AM Mimi Zohar <zohar@...ux.ibm.com> wrote:
> >> >
> >> > The secure boot mode may not be detected on boot for some reason (eg.
> >> > buggy firmware).  This patch attempts one more time to detect the
> >> > secure boot mode.
> >>
> >> Do we have cases where this has actually been seen? I'm not sure what
> >> the circumstances are that would result in this behaviour.
> >
> >
> > We have never seen it in practice, though we only ever do anything with it with x86, so it is possible that some other platforms maybe?
> 
> I'm not sure that it buys us anything to check this in both the boot
> stub and the running kernel. If a platform *is* giving us different
> results, anything else relying on the information from the boot stub
> is also going to be broken, so we should do this centrally rather than
> in the IMA code.

I added this last attempt because I'm seeing this on my laptop, with
some older, buggy firmware.

Mimi