linux-kernel - Re: [PATCH v3] crypto: prefix module autoloading with "crypto-"

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Date:	Fri, 21 Nov 2014 09:31:15 +0100
From:	Mathias Krause <minipli@...glemail.com>
To:	Kees Cook <keescook@...omium.org>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	"linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>
Subject: Re: [PATCH v3] crypto: prefix module autoloading with "crypto-"

On 21 November 2014 02:05, Kees Cook <keescook@...omium.org> wrote:
> This prefixes all crypto module loading with "crypto-" so we never run
> the risk of exposing module auto-loading to userspace via a crypto API,
> as demonstrated by Mathias Krause:
>
> https://lkml.org/lkml/2013/3/4/70
>
> Signed-off-by: Kees Cook <keescook@...omium.org>
> ---
> [...]

Looks good so far, but unfortunately does not solve the problem
completely (af_alg_mod from the link above):

bbox:~# cat /sbin/modlog
#!/bin/sh
exec 1>/tmp/modlog.$$
echo "CMD: $0 $*"
echo "ENV: "
env
exec /sbin/modprobe "$@"
bbox:~# echo /sbin/modlog > /proc/sys/kernel/modprobe
bbox:~# lsmod | grep fat
bbox:~# af_alg_mod 'vfat(blowfish)'
bbox:~# grep CMD /tmp/modlog.*
/tmp/modlog.257:CMD: /sbin/modlog -q -- net-pf-38
/tmp/modlog.261:CMD: /sbin/modlog -q -- algif-hash
/tmp/modlog.265:CMD: /sbin/modlog -q -- crypto-vfat(blowfish)
/tmp/modlog.268:CMD: /sbin/modlog -q -- crypto-vfat(blowfish)-all
/tmp/modlog.272:CMD: /sbin/modlog -q -- vfat
bbox:~# lsmod | grep fat
vfat                   17135  0
fat                    61984  1 vfat
bbox:~#

The last modlog call does not contain the "crypto-" prefix, therefore
happily loads the vfat module.
I guess crypto templates are handled special?

Regards,
Mathias
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