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

Ahmad Fatoum
2021-03-23T16:38:10Z

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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