Re: [PATCH v7 4/6] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys

[Jarkko Sakkinen <jarkko@kernel.org>]

On Fri, 2022-04-15 at 22:56 +0200, Ahmad Fatoum wrote:
> The Cryptographic Acceleration and Assurance Module (CAAM) is an IP core
> built into many newer i.MX and QorIQ SoCs by NXP.
> 
> The CAAM does crypto acceleration, hardware number generation and
> has a blob mechanism for encapsulation/decapsulation of sensitive material.
> 
> This blob mechanism depends on a device specific random 256-bit One Time
> Programmable Master Key that is fused in each SoC at manufacturing
> time. This key is unreadable and can only be used by the CAAM for AES
> encryption/decryption of user data.
> 
> This makes it a suitable backend (source) for kernel trusted keys.
> 
> Previous commits generalized trusted keys to support multiple backends
> and added an API to access the CAAM blob mechanism. Based on these,
> provide the necessary glue to use the CAAM for trusted keys.
> 
> Reviewed-by: David Gstir <david@sigma-star.at>
> Reviewed-by: Pankaj Gupta <pankaj.gupta@nxp.com>
> Tested-by: Tim Harvey <tharvey@gateworks.com>
> Tested-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
> Tested-by: Pankaj Gupta <pankaj.gupta@nxp.com>
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
> v6 -> v7:
>   - Split off MAINTAINERS and documentation chanes into separate patches
>     (Jarkko)
>   - Use new struct caam_blob_info API (Pankaj)
> v5 -> v6:
>   - Rename caam_trusted_key_ops to trusted_key_caam_ops for symmetry
>     with other trust sources (Pankaj)
>   - Collected Pankaj's Reviewed-by
> v4 -> v5:
>   - Collected Reviewed-by's and Tested-by's
>   - Changed modifier to SECURE_KEY for compatibility with linux-imx
>     (Matthias)
> v3 -> v4:
>   - Collected Acked-by's, Reviewed-by's and Tested-by
> v2 -> v3:
>  - add MAINTAINERS entry
> v1 -> v2:
>  - Extend trusted keys documentation for CAAM
> 
> To: David Howells <dhowells@redhat.com>
> To: Jarkko Sakkinen <jarkko@kernel.org>
> To: James Bottomley <jejb@linux.ibm.com>
> To: Mimi Zohar <zohar@linux.ibm.com>
> To: Jonathan Corbet <corbet@lwn.net>
> Cc: James Morris <jmorris@namei.org>
> Cc: "Serge E. Hallyn" <serge@hallyn.com>
> Cc: "Horia Geantă" <horia.geanta@nxp.com>
> Cc: Pankaj Gupta <pankaj.gupta@nxp.com>
> Cc: Herbert Xu <herbert@gondor.apana.org.au>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Biggers <ebiggers@kernel.org>
> Cc: Jan Luebbe <j.luebbe@pengutronix.de>
> Cc: David Gstir <david@sigma-star.at>
> Cc: Richard Weinberger <richard@nod.at>
> Cc: Franck LENORMAND <franck.lenormand@nxp.com>
> Cc: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
> Cc: Sumit Garg <sumit.garg@linaro.org>
> Cc: keyrings@vger.kernel.org
> Cc: linux-crypto@vger.kernel.org
> Cc: linux-doc@vger.kernel.org
> Cc: linux-integrity@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-security-module@vger.kernel.org
> ---
>  .../admin-guide/kernel-parameters.txt         |  1 +
>  include/keys/trusted_caam.h                   | 11 +++
>  security/keys/trusted-keys/Kconfig            | 11 ++-
>  security/keys/trusted-keys/Makefile           |  2 +
>  security/keys/trusted-keys/trusted_caam.c     | 82 +++++++++++++++++++
>  security/keys/trusted-keys/trusted_core.c     |  6 +-
>  6 files changed, 111 insertions(+), 2 deletions(-)
>  create mode 100644 include/keys/trusted_caam.h
>  create mode 100644 security/keys/trusted-keys/trusted_caam.c
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 4deed1908a75..9afb7046ce97 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -5958,6 +5958,7 @@
>                         sources:
>                         - "tpm"
>                         - "tee"
> +                       - "caam"
>                         If not specified then it defaults to iterating through
>                         the trust source list starting with TPM and assigns the
>                         first trust source as a backend which is initialized
> diff --git a/include/keys/trusted_caam.h b/include/keys/trusted_caam.h
> new file mode 100644
> index 000000000000..73fe2f32f65e
> --- /dev/null
> +++ b/include/keys/trusted_caam.h
> @@ -0,0 +1,11 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2021 Pengutronix, Ahmad Fatoum <kernel@pengutronix.de>
> + */
> +
> +#ifndef __CAAM_TRUSTED_KEY_H
> +#define __CAAM_TRUSTED_KEY_H
> +
> +extern struct trusted_key_ops trusted_key_caam_ops;
> +
> +#endif
> diff --git a/security/keys/trusted-keys/Kconfig b/security/keys/trusted-keys/Kconfig
> index fc4abd581abb..dbfdd8536468 100644
> --- a/security/keys/trusted-keys/Kconfig
> +++ b/security/keys/trusted-keys/Kconfig
> @@ -24,6 +24,15 @@ config TRUSTED_KEYS_TEE
>           Enable use of the Trusted Execution Environment (TEE) as trusted
>           key backend.
>  
> -if !TRUSTED_KEYS_TPM && !TRUSTED_KEYS_TEE
> +config TRUSTED_KEYS_CAAM
> +       bool "CAAM-based trusted keys"
> +       depends on CRYPTO_DEV_FSL_CAAM_JR >= TRUSTED_KEYS
> +       select CRYPTO_DEV_FSL_CAAM_BLOB_GEN
> +       default y
> +       help
> +         Enable use of NXP's Cryptographic Accelerator and Assurance Module
> +         (CAAM) as trusted key backend.
> +
> +if !TRUSTED_KEYS_TPM && !TRUSTED_KEYS_TEE && !TRUSTED_KEYS_CAAM
>  comment "No trust source selected!"
>  endif
> diff --git a/security/keys/trusted-keys/Makefile b/security/keys/trusted-keys/Makefile
> index 2e2371eae4d5..735aa0bc08ef 100644
> --- a/security/keys/trusted-keys/Makefile
> +++ b/security/keys/trusted-keys/Makefile
> @@ -12,3 +12,5 @@ trusted-$(CONFIG_TRUSTED_KEYS_TPM) += trusted_tpm2.o
>  trusted-$(CONFIG_TRUSTED_KEYS_TPM) += tpm2key.asn1.o
>  
>  trusted-$(CONFIG_TRUSTED_KEYS_TEE) += trusted_tee.o
> +
> +trusted-$(CONFIG_TRUSTED_KEYS_CAAM) += trusted_caam.o
> diff --git a/security/keys/trusted-keys/trusted_caam.c b/security/keys/trusted-keys/trusted_caam.c
> new file mode 100644
> index 000000000000..46cb2484ec36
> --- /dev/null
> +++ b/security/keys/trusted-keys/trusted_caam.c
> @@ -0,0 +1,82 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2021 Pengutronix, Ahmad Fatoum <kernel@pengutronix.de>
> + */
> +
> +#include <keys/trusted_caam.h>
> +#include <keys/trusted-type.h>
> +#include <linux/build_bug.h>
> +#include <linux/key-type.h>
> +#include <soc/fsl/caam-blob.h>
> +
> +static struct caam_blob_priv *blobifier;
> +
> +#define KEYMOD "SECURE_KEY"
> +
> +static_assert(MAX_KEY_SIZE + CAAM_BLOB_OVERHEAD <= CAAM_BLOB_MAX_LEN);
> +static_assert(MAX_BLOB_SIZE <= CAAM_BLOB_MAX_LEN);
> +
> +static int trusted_caam_seal(struct trusted_key_payload *p, char *datablob)
> +{
> +       int ret;
> +       struct caam_blob_info info = {
> +               .input  = p->key,  .input_len   = p->key_len,
> +               .output = p->blob, .output_len  = MAX_BLOB_SIZE,
> +               .key_mod = KEYMOD, .key_mod_len = sizeof(KEYMOD) - 1,
> +       };
> +
> +       ret = caam_encap_blob(blobifier, &info);
> +       if (ret)
> +               return ret;
> +
> +       p->blob_len = info.output_len;
> +       return 0;
> +}
> +
> +static int trusted_caam_unseal(struct trusted_key_payload *p, char *datablob)
> +{
> +       int ret;
> +       struct caam_blob_info info = {
> +               .input   = p->blob,  .input_len  = p->blob_len,
> +               .output  = p->key,   .output_len = MAX_KEY_SIZE,
> +               .key_mod = KEYMOD,  .key_mod_len = sizeof(KEYMOD) - 1,
> +       };
> +
> +       ret = caam_decap_blob(blobifier, &info);
> +       if (ret)
> +               return ret;
> +
> +       p->key_len = info.output_len;
> +       return 0;
> +}
> +
> +static int trusted_caam_init(void)
> +{
> +       int ret;
> +
> +       blobifier = caam_blob_gen_init();
> +       if (IS_ERR(blobifier)) {
> +               pr_err("Job Ring Device allocation for transform failed\n");
> +               return PTR_ERR(blobifier);
> +       }
> +
> +       ret = register_key_type(&key_type_trusted);
> +       if (ret)
> +               caam_blob_gen_exit(blobifier);
> +
> +       return ret;
> +}
> +
> +static void trusted_caam_exit(void)
> +{
> +       unregister_key_type(&key_type_trusted);
> +       caam_blob_gen_exit(blobifier);
> +}
> +
> +struct trusted_key_ops trusted_key_caam_ops = {
> +       .migratable = 0, /* non-migratable */
> +       .init = trusted_caam_init,
> +       .seal = trusted_caam_seal,
> +       .unseal = trusted_caam_unseal,
> +       .exit = trusted_caam_exit,
> +};
> diff --git a/security/keys/trusted-keys/trusted_core.c b/security/keys/trusted-keys/trusted_core.c
> index 9235fb7d0ec9..c6fc50d67214 100644
> --- a/security/keys/trusted-keys/trusted_core.c
> +++ b/security/keys/trusted-keys/trusted_core.c
> @@ -9,6 +9,7 @@
>  #include <keys/user-type.h>
>  #include <keys/trusted-type.h>
>  #include <keys/trusted_tee.h>
> +#include <keys/trusted_caam.h>
>  #include <keys/trusted_tpm.h>
>  #include <linux/capability.h>
>  #include <linux/err.h>
> @@ -29,7 +30,7 @@ MODULE_PARM_DESC(rng, "Select trusted key RNG");
>  
>  static char *trusted_key_source;
>  module_param_named(source, trusted_key_source, charp, 0);
> -MODULE_PARM_DESC(source, "Select trusted keys source (tpm or tee)");
> +MODULE_PARM_DESC(source, "Select trusted keys source (tpm, tee or caam)");
>  
>  static const struct trusted_key_source trusted_key_sources[] = {
>  #if defined(CONFIG_TRUSTED_KEYS_TPM)
> @@ -38,6 +39,9 @@ static const struct trusted_key_source trusted_key_sources[] = {
>  #if defined(CONFIG_TRUSTED_KEYS_TEE)
>         { "tee", &trusted_key_tee_ops },
>  #endif
> +#if defined(CONFIG_TRUSTED_KEYS_CAAM)
> +       { "caam", &trusted_key_caam_ops },
> +#endif
>  };
>  
>  DEFINE_STATIC_CALL_NULL(trusted_key_init, *trusted_key_sources[0].ops->init);


Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

BR, Jarkko