linux-kernel - Re: [PATCH 5/5] efi: Make efivarfs entries immutable by default

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Date:	Mon, 15 Feb 2016 10:50:04 +0000
From:	Matt Fleming <matt@...eblueprint.co.uk>
To:	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H . Peter Anvin" <hpa@...or.com>
Cc:	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Peter Jones <pjones@...hat.com>, linux-kernel@...r.kernel.org,
	linux-efi@...r.kernel.org, "Lee, Chun-Yi" <jlee@...e.com>,
	Matthew Garrett <mjg59@...eos.com>,
	Laszlo Ersek <lersek@...hat.com>
Subject: Re: [PATCH 5/5] efi: Make efivarfs entries immutable by default

On Fri, 12 Feb, at 11:27:12AM, Matt Fleming wrote:
> From: Peter Jones <pjones@...hat.com>
> 
> "rm -rf" is bricking some peoples' laptops because of variables being
> used to store non-reinitializable firmware driver data that's required
> to POST the hardware.
> 
> These are 100% bugs, and they need to be fixed, but in the mean time it
> shouldn't be easy to *accidentally* brick machines.
> 
> We have to have delete working, and picking which variables do and don't
> work for deletion is quite intractable, so instead make everything
> immutable by default (except for a whitelist), and make tools that
> aren't quite so broad-spectrum unset the immutable flag.
> 
> Signed-off-by: Peter Jones <pjones@...hat.com>
> Tested-by: "Lee, Chun-Yi" <jlee@...e.com>
> Acked-by: Matthew Garrett <mjg59@...eos.com>
> Signed-off-by: Matt Fleming <matt@...eblueprint.co.uk>
> ---
>  Documentation/filesystems/efivarfs.txt         |  7 +++
>  drivers/firmware/efi/vars.c                    | 87 +++++++++++++++++++-------
>  fs/efivarfs/file.c                             | 70 +++++++++++++++++++++
>  fs/efivarfs/inode.c                            | 30 +++++----
>  fs/efivarfs/internal.h                         |  3 +-
>  fs/efivarfs/super.c                            |  9 ++-
>  include/linux/efi.h                            |  2 +
>  tools/testing/selftests/efivarfs/efivarfs.sh   | 19 +++++-
>  tools/testing/selftests/efivarfs/open-unlink.c | 72 ++++++++++++++++++++-
>  9 files changed, 258 insertions(+), 41 deletions(-)

Folks, please hold off on merging this patch as Laszlo has raised a
good point about including the efi-pstore variables in the whitelist.