Re: [PATCH v1 0/3] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys

From: Ahmad Fatoum <a.fatoum@pengutronix.de>
To: "Horia Geantă" <horia.geanta@nxp.com>,
	"Jarkko Sakkinen" <jarkko@kernel.org>,
	"Mimi Zohar" <zohar@linux.ibm.com>,
	"Aymen Sghaier" <aymen.sghaier@nxp.com>,
	"Herbert Xu" <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>,
	"James Bottomley" <jejb@linux.ibm.com>
Cc: "kernel@pengutronix.de" <kernel@pengutronix.de>,
	David Howells <dhowells@redhat.com>,
	James Morris <jmorris@namei.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	Steffen Trumtrar <s.trumtrar@pengutronix.de>,
	Udit Agarwal <udit.agarwal@nxp.com>,
	Jan Luebbe <j.luebbe@pengutronix.de>,
	David Gstir <david@sigma-star.at>,
	Franck Lenormand <franck.lenormand@nxp.com>,
	Sumit Garg <sumit.garg@linaro.org>,
	"linux-integrity@vger.kernel.org"
	<linux-integrity@vger.kernel.org>,
	"keyrings@vger.kernel.org" <keyrings@vger.kernel.org>,
	"linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-security-module@vger.kernel.org" 
	<linux-security-module@vger.kernel.org>
Subject: Re: [PATCH v1 0/3] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys
Date: Tue, 23 Mar 2021 17:37:17 +0100	[thread overview]
Message-ID: <a07e5544-1e62-a8da-485e-6fcafd16bab9@pengutronix.de> (raw)
In-Reply-To: <f0f43b30-3dfb-c2a0-7f69-6e5488f871cd@nxp.com>

Hello Horia,

On 21.03.21 21:01, Horia Geantă wrote:
>>  - [RFC] drivers: crypto: caam: key: Add caam_tk key type
>>    Franck added[3] a new "caam_tk" key type based on Udit's work. The key
>>    material stays within the kernel only, but can optionally be user-set
>>    instead of coming from RNG. James voiced the opinion that there should
>>    be just one user-facing generic wrap/unwrap key type with multiple
>>    possible handlers. David suggested trusted keys.
>>
> The whole point was to use caam "black blobs", with the main advantage of
> keys being kept encrypted in memory after "unsealing" the blobs.
> (Keys in blobs are encrypted with a persistent BKEK - blob KEK, derived from
> fuse-based OTPMK. OTOH black keys are keys encrypted with an ephemeral, random
> KEK that is stored in an internal caam register. When a black blob is unsealed,
> the key is practically rekeyed, the random key replacing the BKEK; key is never
> exposed in plaintext, rekeying happens in caam).
> 
> Current implementation uses "red blobs", which means keys are left unprotected
> in memory after blobs are unsealed.

Oh. I will reread the series when sending the v2 cover letter. Thanks for spotting.

(Sorry for the noise, missed this question first time)

>>  - Introduce TEE based Trusted Keys support
>>    Sumit reworked[4] trusted keys to support multiple possible backends with
>>    one chosen at boot time and added a new TEE backend along with TPM.
>>    This now sits in Jarkko's master branch to be sent out for v5.13
>>
>> This patch series builds on top of Sumit's rework to have the CAAM as yet another
>> trusted key backend.
>>
> Shouldn't the description under TRUSTED_KEYS (in security/keys/Kconfig)
> be updated to reflect the availability of multiple backends?
> 
> Thanks,
> Horia
> 

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