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

Richard Weinberger richard.weinberger at gmail.com
Tue Mar 16 23:10:54 UTC 2021


On Tue, Mar 16, 2021 at 6:24 PM Ahmad Fatoum <a.fatoum at pengutronix.de> wrote:
> 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 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. 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.
>  - 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.MX6DL.

Do have this series also in a git repo to pull from?
I'd like to give it a test on various systems.

> Looking forward to your feedback.

Thanks for working on this! David and I will have a closer look these days.


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