linux-kernel - Re: Firmware signing -- Re: [PATCH 00/27] security, efi: Add kernel lockdown

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Date:   Wed, 15 Nov 2017 06:49:57 -0500
From:   Mimi Zohar <zohar@...ux.vnet.ibm.com>
To:     "Luis R. Rodriguez" <mcgrof@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Johannes Berg <johannes@...solutions.net>
Cc:     Matthew Garrett <mjg59@...gle.com>,
        David Howells <dhowells@...hat.com>,
        Alan Cox <gnomes@...rguk.ukuu.org.uk>,
        "AKASHI, Takahiro" <takahiro.akashi@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jan Blunck <jblunck@...radead.org>,
        Julia Lawall <julia.lawall@...6.fr>,
        Marcus Meissner <meissner@...e.de>, Gary Lin <GLin@...e.com>,
        LSM List <linux-security-module@...r.kernel.org>,
        linux-efi <linux-efi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Firmware signing -- Re: [PATCH 00/27] security, efi: Add kernel
 lockdown

On Tue, 2017-11-14 at 21:50 +0100, Luis R. Rodriguez wrote:

> Johannes made cfg80211 recently just use request_firmware() now via commit on
> linux-next 90a53e4432 ("cfg80211: implement regdb signature checking") [0] as
> he got tired of waiting firmware signing, but note he implemented a signature
> checking on its own so he open codes verify_pkcs7_signature() after the
> request_firmware() call. If we are happy to live with this, then so be it.
> 
> [0] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=90a53e4432b12288316efaa5f308adafb8d304b0

Johannes was tired of waiting?  Commit 5a9196d "ima: add support for
measuring and appraising firmware" has been in the kernel since linux-
3.17.

The original firmware hook for verifying firmware signatures were
replaced with the common LSM pre and post kernel_read_file() hooks
in linux-4.6.y.

Even if you wanted to support firmware signature verification without
IMA-appraisal, it should be using the LSM hooks.

Mimi