linux-kernel - Re: [PATCH] builddeb: Support signing kernels with a Machine Owner Key

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Message-ID: <CAMj1kXEJ+RThJ83H2VNAmOKkVdhTAUCUF61u9JTv6ccc9uVTDw@mail.gmail.com>
Date:   Thu, 14 Oct 2021 11:46:48 +0200
From:   Ard Biesheuvel <ardb@...nel.org>
To:     "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc:     Masahiro Yamada <masahiroy@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        efi@...ts.einval.com, debian-kernel@...ts.debian.org,
        linux-efi <linux-efi@...r.kernel.org>
Subject: Re: [PATCH] builddeb: Support signing kernels with a Machine Owner Key

On Wed, 13 Oct 2021 at 22:07, Matthew Wilcox (Oracle)
<willy@...radead.org> wrote:
>
> If the config file specifies a signing key, use it to sign
> the kernel so that machines with SecureBoot enabled can boot.
> See https://wiki.debian.org/SecureBoot
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>

For the change itself

Acked-by: Ard Biesheuvel <ardb@...nel.org>

although I'd suggest to fix the subject not to refer to Machine Owner
Keys, as I don't see anything shim related here (i.e., if you sign
using a key that is listed in db, it should also work)


> ---
>  scripts/package/builddeb | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/scripts/package/builddeb b/scripts/package/builddeb
> index 91a502bb97e8..4fa6ff2b5cac 100755
> --- a/scripts/package/builddeb
> +++ b/scripts/package/builddeb
> @@ -147,7 +147,15 @@ else
>         cp System.map "$tmpdir/boot/System.map-$version"
>         cp $KCONFIG_CONFIG "$tmpdir/boot/config-$version"
>  fi
> -cp "$($MAKE -s -f $srctree/Makefile image_name)" "$tmpdir/$installed_image_path"
> +
> +vmlinux=$($MAKE -s -f $srctree/Makefile image_name)
> +if is_enabled CONFIG_MODULE_SIG; then
> +       cert=$srctree/$(grep ^CONFIG_MODULE_SIG_KEY= include/config/auto.conf | cut -d\" -f2)
> +       key=${cert%pem}priv
> +       sbsign --key $key --cert $cert "$vmlinux" --output "$tmpdir/$installed_image_path"
> +else
> +       cp "$vmlinux" "$tmpdir/$installed_image_path"
> +fi
>
>  if is_enabled CONFIG_OF_EARLY_FLATTREE; then
>         # Only some architectures with OF support have this target
> --
> 2.32.0
>