linux-kernel - Re: [PATCH 0/3] integrity: Load certs from EFI MOK config table

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Date:   Wed, 26 Aug 2020 07:55:10 -0400
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Lenny Szubowicz <lszubowi@...hat.com>,
        linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
        platform-driver-x86@...r.kernel.org,
        linux-security-module@...r.kernel.org, ardb@...nel.org,
        jmorris@...ei.org, serge@...lyn.com, keescook@...omium.org,
        bp@...en8.de, pjones@...hat.com, dhowells@...hat.com,
        prarit@...hat.com
Subject: Re: [PATCH 0/3] integrity: Load certs from EFI MOK config table

Hi Lenny,

On Tue, 2020-08-25 at 23:44 -0400, Lenny Szubowicz wrote:
> Because of system-specific EFI firmware limitations,
> EFI volatile variables may not be capable of holding the
> required contents of the Machine Owner Key (MOK) certificate
> store. Therefore, an EFI boot loader may pass the MOK certs
> via a EFI configuration table created specifically for this
> purpose to avoid this firmware limitation.
> 
> An EFI configuration table is a simpler and more robust mechanism
> compared to EFI variables and is well suited for one-way passage
> of static information from a pre-OS environment to the kernel.
> 
> This patch set does not remove the support for loading certs
> from the EFI MOK variables into the platform key ring.
> However, if both the EFI MOK config table and corresponding
> EFI MOK variables are present, the MOK table is used as the
> source of MOK certs.
> 
> The contents of the individual named MOK config table entries are
> made available to user space via read-only sysfs binary files under:
> 
> 	/sys/firmware/efi/mok-variables/

Please include a security section in this cover letter with a
comparison of the MoK variables and the EFI configuration table
security (eg. same mechanism?).  Has mokutil been updated?  If so,
please provide a link.

Mimi