Re: [PATCH 2/3] ARM: mxs: crypto: Add Freescale MXS DCP driver

From: Herbert Xu <herbert@gondor.apana.org.au>
To: Marek Vasut <marex@denx.de>
Cc: "Christoph G. Baumann" <cb@sgoc.de>,
	linux-crypto@vger.kernel.org, Shawn Guo <shawn.guo@linaro.org>,
	Fabio Estevam <festevam@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	Tobias Rauter <tobiasrauter@gmail.com>
Subject: Re: [PATCH 2/3] ARM: mxs: crypto: Add Freescale MXS DCP driver
Date: Tue, 8 Oct 2013 15:36:31 +1100	[thread overview]
Message-ID: <20131008043631.GA18365@gondor.apana.org.au> (raw)
In-Reply-To: <201310071748.27150.marex@denx.de>

On Mon, Oct 07, 2013 at 05:48:26PM +0200, Marek Vasut wrote:
> Hello Christoph,
> 
> > Hello Marek,
> > 
> > > Marek Vasut <marex@denx.de> hat am 28. September 2013 um 05:35 geschrieben:
> > > [...]
> > >
> > > > > 3) What are those ugly new IOCTLs in the dcp.c driver?
> > > > 
> > > > When I firstly posted the driver in the mailinglist, there where one
> > > > person who actually used this interface (it was introduced in
> > > > Freescale's SDK) to use the OTP keys for crypto. As far as I have
> > > > seen, the crypto API does not support such keys (i.e. there seems to
> > > > be no way to tell a driver to use some kind of special keys - which
> > > > are not delivered by the user - via the API).
> > > > Therefore I added this miscdevice and adopted Freescale's interface.
> > > 
> > > The keys are programmed into the OTP registers, correct? There is OCOTP d
> > >river 
> > >for the MX23/MX28 OTP hardware. This is what should have been used then. 
> > > NOTE: This IOCTL interface seems like quite an abusive way to allow userl
> > >and to 
> > >access the crypto API in kernel. I understand this is used by some Freesc
> > >ale tool, but won't it be better to fix the Freescale tool instead ?
> > 
> > the IOCTL interface is used to AES encrypt a bootstream with the AES key in
> > OCOTP.
> > The idea is that only the DCP can read/access the key once it has been
> > programmed
> > into the OCOTP. If the crypto API has means to tell the DCP to use the key
> > from OCOTP, the tool from Freescale is a minor problem.
> 
> Ah right. I suspect the crypto API services shall not be exported into userland 
> at all, yes ? So there has to be some kind of workaround here for this freescale 
> tool, which is rather unfortunate.

These ioctls have to go.  I should have never let them through in
the first place.  Can someone cook up a patch to kill them please?

Thanks,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt