linux-kernel - Re: [GIT PULL] Kernel lockdown for secure boot

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Date:   Tue, 03 Apr 2018 16:29:48 +0000
From:   Matthew Garrett <mjg59@...gle.com>
To:     luto@...nel.org
Cc:     David Howells <dhowells@...hat.com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>, jmorris@...ei.org,
        Alan Cox <gnomes@...rguk.ukuu.org.uk>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        jforbes@...hat.com, linux-man@...r.kernel.org, jlee@...e.com,
        LSM List <linux-security-module@...r.kernel.org>,
        linux-api@...r.kernel.org, Kees Cook <keescook@...omium.org>,
        linux-efi <linux-efi@...r.kernel.org>
Subject: Re: [GIT PULL] Kernel lockdown for secure boot

On Tue, Apr 3, 2018 at 8:11 AM Andy Lutomirski <luto@...nel.org> wrote:
> Can you explain that much more clearly?  I'm asking why booting via
> UEFI Secure Boot should enable lockdown, and I don't see what this has
> to do with kexec.  And "someone blacklist[ing] your key in the
> bootloader" sounds like a political issue, not a technical issue.

A kernel that allows users arbitrary access to ring 0 is just an
overfeatured bootloader. Why would you want secure boot in that case?