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From:   Matthew Garrett <mjg59@google.com>
Date:   Tue, 03 Apr 2018 16:29:48 +0000
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Subject: Re: [GIT PULL] Kernel lockdown for secure boot
To:     luto@kernel.org
Cc:     David Howells <dhowells@redhat.com>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>, jmorris@namei.org,
        Alan Cox <gnomes@lxorguk.ukuu.org.uk>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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        jforbes@redhat.com, linux-man@vger.kernel.org, jlee@suse.com,
        LSM List <linux-security-module@vger.kernel.org>,
        linux-api@vger.kernel.org, Kees Cook <keescook@chromium.org>,
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On Tue, Apr 3, 2018 at 8:11 AM Andy Lutomirski <luto@kernel.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?