From mboxrd@z Thu Jan  1 00:00:00 1970
From: ebiederm@xmission.com (Eric W. Biederman)
Subject: Re: [GIT PULL] Kernel lockdown for secure boot
Date: Wed, 04 Apr 2018 10:43:57 -0500
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In-Reply-To: <20736.1522829117@warthog.procyon.org.uk> (David Howells's
        message of "Wed, 04 Apr 2018 09:05:17 +0100")
Sender: linux-kernel-owner@vger.kernel.org
To: David Howells <dhowells@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>, Jann Horn <jannh@google.com>, Linus Torvalds <torvalds@linux-foundation.org>, Matthew Garrett <mjg59@google.com>, Ard Biesheuvel <ard.biesheuvel@linaro.org>, James Morris <jmorris@namei.org>, Alan Cox <gnomes@lxorguk.ukuu.org.uk>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Justin Forbes <jforbes@redhat.com>, linux-man <linux-man@vger.kernel.org>, joeyli <jlee@suse.com>, LSM List <linux-security-module@vger.kernel.org>, Linux API <linux-api@vger.kernel.org>, Kees Cook <keescook@chromium.org>, linux-efi <linux-efi@vger.kernel.org>
List-Id: linux-api@vger.kernel.org

David Howells <dhowells@redhat.com> writes:

> Andy Lutomirski <luto@kernel.org> wrote:
>
>> As far as I can tell, what's really going on here is that there's a
>> significant contingent here that wants to prevent Linux from
>> chainloading something that isn't Linux.
>
> You have completely the wrong end of the stick.  No one has said that or even
> implied that.  You are alleging dishonesty on our part.
>
> What we *have* said is that *if* we want to pass the secure boot state across
> kexec, then we have to make sure that:
>
>  (1) no one tampers with the intermediate kernel between boot and kexec
>      otherwise the secure boot state is effectively invalidated, and
>
>  (2) the image that gets kexec'ed is trusted.
>
> Remember: you cannot know (2) if you don't have (1).
>
> And if someone tampers with the aim of breaking, say, Windows, then someone,
> e.g.  Microsoft, might blacklist the shim.

*Wow*   You just denied this isn't about not booting Windows and a few
lines later said that is your concern.

I was thinking I would have to dig up old archives where I had been told
this before, but you just nicely repeated all of the old arguments so I
don't see the point.

Eric