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

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Date:   Tue, 03 Apr 2018 23:09:27 +0000
From:   Matthew Garrett <mjg59@...gle.com>
To:     luto@...nel.org
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        David Howells <dhowells@...hat.com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>, jmorris@...ei.org,
        Alan Cox <gnomes@...rguk.ukuu.org.uk>,
        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 3:53 PM Andy Lutomirski <luto@...nel.org> wrote:
> On Tue, Apr 3, 2018 at 3:51 PM, Matthew Garrett <mjg59@...gle.com> wrote:
> > Lockdown is clearly useful without Secure Boot (and I intend to deploy
it
> > that way for various things), but I still don't understand why you feel
> > that the common case of booting a kernel from a boot chain that's widely
> > trusted derives no benefit from it being harder to subvert that kernel
into
> > subverting that boot chain. For cases where you're self-signing and feel
> > happy about that, you just set CONFIG_LOCK_DOWN_IN_EFI_SECURE_BOOT to n
and
> > everyone's happy?

> I would like to see distros that want Secure Boot to annoy users by
> enabling Lockdown be honest about the fact that it's an annoyance and
> adds very little value by having to carry a patch that was rejected by
> the upstream kernel.

I disagree with the assertion that it adds very little value, but if you
want to reject a technically useful patch for political reasons then I'm
well beyond the point of caring.