[PATCH v9 0/7] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys
Ahmad Fatoum
a.fatoum at pengutronix.de
Wed May 11 10:47:02 UTC 2022
Hello Michael,
On 06.05.22 12:52, Michael Walle wrote:
> Am 2022-05-06 08:25, schrieb Ahmad Fatoum:
>> Series applies on top of v5.18-rc5. Would be great if this could make it
>> into v5.19.
>>
>> v8 was here:
>> https://lore.kernel.org/linux-integrity/09e2552c-7392-e1da-926b-53c7db0b118d@pengutronix.de
>>
>> Changelog is beneath each individual patch. Compared to v8, only code
>> change is checking whether CAAM can support blobbing at init-time as
>> apparently some Layerscape SoCs are available in a non-E(ncryption)
>> variant that doesn't do AES. Previously, adding trusted keys on such
>> SoCs would return an error with a cryptic error message.
>>
>>
>> The Cryptographic Acceleration and Assurance Module (CAAM) is an IP core
>> built into many newer i.MX and QorIQ SoCs by NXP.
>>
>> Its blob mechanism can AES encrypt/decrypt user data using a unique
>> never-disclosed device-specific key.
>>
>> There has been multiple discussions on how to represent this within the kernel:
>>
>> The Cryptographic Acceleration and Assurance Module (CAAM) is an IP core
>> built into many newer i.MX and QorIQ SoCs by NXP.
>>
>> Its blob mechanism can AES encrypt/decrypt user data using a unique
>> never-disclosed device-specific key. There has been multiple
>> discussions on how to represent this within the kernel:
>>
>> - [RFC] crypto: caam - add red blobifier
>> Steffen implemented[1] a PoC sysfs driver to start a discussion on how to
>> best integrate the blob mechanism.
>> Mimi suggested that it could be used to implement trusted keys.
>> Trusted keys back then were a TPM-only feature.
>>
>> - security/keys/secure_key: Adds the secure key support based on CAAM.
>> Udit Agarwal added[2] a new "secure" key type with the CAAM as backend.
>> The key material stays within the kernel only.
>> Mimi and James agreed that this needs a generic interface, not specific
>> to CAAM. Mimi suggested trusted keys. Jan noted that this could serve as
>> basis for TEE-backed keys.
>>
>> - [RFC] drivers: crypto: caam: key: Add caam_tk key type
>> Franck added[3] a new "caam_tk" key type based on Udit's work. This time
>> it uses CAAM "black blobs" instead of "red blobs", so key material stays
>> within the CAAM and isn't exposed to kernel in plaintext.
>> 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.
>>
>> - 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.
>>
>> The CAAM bits are based on Steffen's initial patch from 2015. His work had been
>> used in the field for some years now, so I preferred not to deviate
>> too much from it.
>>
>> This series has been tested with dmcrypt[5] on an i.MX6Q/DL and an i.MX8M[6].
>>
>> Looking forward to your feedback.
>
> For the whole series:
>
> Tested-by: Michael Walle <michael at walle.cc> # on ls1028a (non-E and E)
Thanks! Did you test checkpatch.pl and make htmldocs/pdfdocs too
or should I add the Tested-by just for the first 5 patches?
Cheers,
Ahmad
>
> -michael
>
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