From:   Kalyani Akula <kalyania@xilinx.com>
To:     Stephan Mueller <smueller@chronox.de>
CC:     "herbert@gondor.apana.org.au" <herbert@gondor.apana.org.au>,
        "davem@davemloft.net" <davem@davemloft.net>,
        "linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [RFC PATCH 4/5] crypto: Adds user space interface for
 ALG_SET_KEY_TYPE
Thread-Topic: [RFC PATCH 4/5] crypto: Adds user space interface for
 ALG_SET_KEY_TYPE
Thread-Index: AQHUrjLRC0KQY4vUUEiutylzuXEA7qWzVM+AgJUjQyA=
Date:   Mon, 22 Apr 2019 09:17:55 +0000
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Hi Stephan,

Sorry for the delayed response.

Please find my response/doubts inline.

> -----Original Message-----
> From: Stephan Mueller <smueller@chronox.de>
> Sent: Thursday, January 17, 2019 5:04 PM
> To: Kalyani Akula <kalyania@xilinx.com>
> Cc: herbert@gondor.apana.org.au; davem@davemloft.net; linux-
> crypto@vger.kernel.org; linux-kernel@vger.kernel.org; Kalyani Akula
> <kalyania@xilinx.com>; Sarat Chand Savitala <saratcha@xilinx.com>
> Subject: Re: [RFC PATCH 4/5] crypto: Adds user space interface for
> ALG_SET_KEY_TYPE
>=20
> Am Donnerstag, 17. Januar 2019, 08:02:20 CET schrieb Kalyani Akula:
>=20
> Hi Kalyani,
>=20
> > ALG_SET_KEY_TYPE requires caller to pass the key_type to be used for
> > AES encryption/decryption.
> >
> > Sometimes the cipher key will be stored in the device's hardware. So,
> > there is a need to specify the information about the key to use for
> > AES operations.
> >
> > In Xilinx ZynqMP SoC, below key types are available
> >
> > 1. Device key, which is flashed in the HW.
> >
> > 2. PUF KEK, which can be regenerated using the
> >    helper data programmed in the HW.
> >
> > 3. User supplied key.
> >
> > So to choose the AES key to be used, this patch adds key-type attribute=
.
>=20
> You expose your particular driver interface to user space. So, user space
> would need the details of you driver to know what to set. If another driv=
er
> has such key type support, user space would need to know about that, too.=
 I
> do not think this is a wise idea.
>=20
> If we are going to have such a keytype selection, there must be a common
> user space interface for all drivers. I.e. define common key types the dr=
ivers
> then can map to their particular key type interface.
[kalyani] Agree, now we have 3 basic key types and we can define them as be=
low
eFuse key
PUF KEK
User supplied key
But for our upcoming platform there are multiple flavors of above keys,=20
those may not be common for other drivers.=20
I will check on this further and update.
>=20
> Besides, seem to be more a key handling issue. Wouldn't it make sense to
> rather have such issue solved with key rings than in the kernel crypto AP=
I?
[kalyani] Can you please elaborate on this further ?
>=20
> Ciao
> Stephan
>=20