From: Marek Vasut Subject: Re: [PATCH 2/3] ARM: mxs: crypto: Add Freescale MXS DCP driver Date: Mon, 7 Oct 2013 17:48:26 +0200 Message-ID: <201310071748.27150.marex@denx.de> References: <1380194306-5243-1-git-send-email-marex@denx.de> <201309280535.33672.marex@denx.de> <632804650.191291.1381139440065.open-xchange@email.1und1.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Herbert Xu , Tobias Rauter , linux-crypto@vger.kernel.org, Shawn Guo , Fabio Estevam , "David S. Miller" , "linux-arm-kernel@lists.infradead.org" To: "Christoph G. Baumann" Return-path: In-Reply-To: <632804650.191291.1381139440065.open-xchange@email.1und1.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org List-Id: linux-crypto.vger.kernel.org Hello Christoph, > Hello Marek, > > > Marek Vasut 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. Thanks for clearing this up. Best regards, Marek Vasut