linux-kernel - Re: crypto: user - crypto_alg

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Date:	Tue, 25 Nov 2014 10:24:08 +0100
From:	Steffen Klassert <steffen.klassert@...unet.com>
To:	Herbert Xu <herbert@...dor.apana.org.au>
CC:	Stephan Mueller <smueller@...onox.de>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: crypto: user - crypto_alg_match removal

On Tue, Nov 25, 2014 at 05:06:01PM +0800, Herbert Xu wrote:
> On Tue, Nov 25, 2014 at 09:42:25AM +0100, Steffen Klassert wrote:
> >
> > Well, I think there is a small but important difference. If a user
> > requests a driver name that would match an algorithm name (i.e. cbc(aes)
> > instead of cbc(aes-asm)) crypto_alg_lookup() returns the algorithm with
> > the highest priority instead of telling that we don't have a driver with
> > the name cbc(aes).
> 
> Does this matter though? The current user interface is only used to
> query specific driver names which should never be equal to an
> algorithm name.  So doing so already invokes undefined behaviour.
> 

Using an algorithm name as a driver name is a misconfiguration.
We currently, catch these kind of misconfigurations beacuse
we match only driver names with crypto_alg_match().

crypto_alg_lookup() would return the algorithm with the highest
priority in this case and this would indeed lead to undefined
behaviour.
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