Re: [PATCH v4 4/5] crypto: caam - add in-kernel interface for blob generator

From: Ahmad Fatoum <a.fatoum@pengutronix.de>
To: Jarkko Sakkinen <jarkko@kernel.org>
Cc: "Horia Geantă" <horia.geanta@nxp.com>,
	"Aymen Sghaier" <aymen.sghaier@nxp.com>,
	"Herbert Xu" <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>,
	kernel@pengutronix.de, "David Gstir" <david@sigma-star.at>,
	"Tim Harvey" <tharvey@gateworks.com>,
	"James Bottomley" <jejb@linux.ibm.com>,
	"Mimi Zohar" <zohar@linux.ibm.com>,
	"David Howells" <dhowells@redhat.com>,
	"James Morris" <jmorris@namei.org>,
	"Eric Biggers" <ebiggers@kernel.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	"Udit Agarwal" <udit.agarwal@nxp.com>,
	"Jan Luebbe" <j.luebbe@pengutronix.de>,
	"Richard Weinberger" <richard@nod.at>,
	"Franck LENORMAND" <franck.lenormand@nxp.com>,
	"Sumit Garg" <sumit.garg@linaro.org>,
	linux-integrity@vger.kernel.org, keyrings@vger.kernel.org,
	linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-security-module@vger.kernel.org
Subject: Re: [PATCH v4 4/5] crypto: caam - add in-kernel interface for blob generator
Date: Mon, 13 Dec 2021 11:34:39 +0100	[thread overview]
Message-ID: <3e33a215-12d2-da30-d1e1-2fde753a7a0a@pengutronix.de> (raw)
In-Reply-To: <YawFYFV8xGIPZvUJ@iki.fi>

Hello Jarkko,

On 05.12.21 01:18, Jarkko Sakkinen wrote:
> On Mon, Oct 11, 2021 at 12:02:37PM +0200, Ahmad Fatoum wrote:
>> The CAAM can be used to protect user-defined data across system reboot:
>>
>>   - When the system is fused and boots into secure state, the master
>>     key is a unique never-disclosed device-specific key
>>   - random key is encrypted by key derived from master key
>>   - data is encrypted using the random key
>>   - encrypted data and its encrypted random key are stored alongside
>>   - This blob can now be safely stored in non-volatile memory
>>
>> On next power-on:
>>   - blob is loaded into CAAM
>>   - CAAM writes decrypted data either into memory or key register
>>
>> Add functions to realize encrypting and decrypting into memory alongside
>> the CAAM driver.
>>
>> They will be used in a later commit as a source for the trusted key
>> seal/unseal mechanism.
>>
>> Reviewed-by: David Gstir <david@sigma-star.at>
>> Tested-By: Tim Harvey <tharvey@gateworks.com>
>> Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
>> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> 
> What is CAAM? This is missing.

That's Crypto Accelerator on NXP SoCs. There is a description in the cover
letter and in the follow-up patch wiring this into the new trusted key
source. I didn't elaborate on this here as this patch touches
drivers/crypto/caam and I assumed familiarity.

For v5, I can add some extra info:

"The NXP Cryptographic Acceleration and Assurance Module (CAAM)
 can be used to protect user-defined data across system reboot..."

Sounds good? Does the last patch in the series look ok to you?

Cheers,
Ahmad

> 
> /Jarkko
> 

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