linux-kernel - Re: [PATCH] KEYS: Sort out big

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Message-ID: <20160730170720.GA10208@kroah.com>
Date:	Sat, 30 Jul 2016 10:07:20 -0700
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Kirill Marinushkin <k.marinushkin@...il.com>
Cc:	dhowells@...hat.com, zer0mem@...oo.com, serge@...lyn.com,
	james.l.morris@...cle.com, keyrings@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] KEYS: Sort out big_key initialisation

On Sat, Jul 30, 2016 at 06:21:41PM +0200, Kirill Marinushkin wrote:
> big_key has two separate initialisation functions, one that registers the
> key type and one that registers the crypto.  If the key type fails to
> register, there's no problem if the crypto registers successfully because
> there's no way to reach the crypto except through the key type.
> 
> However, if the key type registers successfully but the crypto does not,
> big_key_rng and big_key_blkcipher may end up set to NULL - but the code
> neither checks for this nor unregisters the big key key type.
> 
> Furthermore, since the key type is registered before the crypto, it is
> theoretically possible for the kernel to try adding a big_key before the
> crypto is set up, leading to the same effect.
> 
> Fix this by merging big_key_crypto_init() and big_key_init() and calling
> the resulting function late.  If they're going to be encrypted, we
> shouldn't be creating big_keys before we have the facilities to do the
> encryption available.  The key type registration is also moved after the
> crypto initialisation.
> 
> The fix also includes message printing on failure.
> 
> If the big_key type isn't correctly set up, simply doing:
> 
>     dd if=/dev/zero bs=4096 count=1 | keyctl padd big_key a @s
> 
> ought to cause an oops.
> 
> Signed-off-by: David Howells <dhowells@...hat.com>
> Signed-off-by: Kirill Marinushkin <k.marinushkin@...il.com>
> ---
>  security/keys/Kconfig   |  2 +-
>  security/keys/big_key.c | 62 +++++++++++++++++++++++++++----------------------
>  2 files changed, 35 insertions(+), 29 deletions(-)


<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read Documentation/stable_kernel_rules.txt
for how to do this properly.

</formletter>