RE: [EXT] [PATCH v6 3/4] crypto: caam - add in-kernel interface for blob generator

[Pankaj Gupta <pankaj.gupta@nxp.com>]

Hi Ahmad,

Please find the comments in-line.

Regards
Pankaj

> -----Original Message-----
> From: Ahmad Fatoum <a.fatoum@pengutronix.de>
> Sent: Wednesday, March 16, 2022 10:14 PM
> To: Horia Geanta <horia.geanta@nxp.com>; Pankaj Gupta
> <pankaj.gupta@nxp.com>; Herbert Xu <herbert@gondor.apana.org.au>;
> David S. Miller <davem@davemloft.net>
> Cc: kernel@pengutronix.de; David Gstir <david@sigma-star.at>;
> tharvey@gateworks.com; Matthias Schiffer <matthias.schiffer@ew.tq-
> group.com>; Ahmad Fatoum <a.fatoum@pengutronix.de>; James Bottomley
> <jejb@linux.ibm.com>; Jarkko Sakkinen <jarkko@kernel.org>; Mimi Zohar
> <zohar@linux.ibm.com>; David Howells <dhowells@redhat.com>; James
> Morris <jmorris@namei.org>; Eric Biggers <ebiggers@kernel.org>; Serge E.
> Hallyn <serge@hallyn.com>; Jan Luebbe <j.luebbe@pengutronix.de>;
> Richard Weinberger <richard@nod.at>; Franck Lenormand
> <franck.lenormand@nxp.com>; Sumit Garg <sumit.garg@linaro.org>; linux-
> integrity@vger.kernel.org; keyrings@vger.kernel.org; linux-
> crypto@vger.kernel.org; linux-kernel@vger.kernel.org; linux-security-
> module@vger.kernel.org
> Subject: [EXT] [PATCH v6 3/4] crypto: caam - add in-kernel interface for blob
> generator
> 
> Caution: EXT Email
> 
> The NXP Cryptographic Acceleration and Assurance Module (CAAM) can be
> used to protect user-defined data across system reboot:
> 
>   - When the system is fused and boots into secure state, the master
>     key is a unique never-disclosed device-specific key
>   - random key is encrypted by key derived from master key
>   - data is encrypted using the random key
>   - encrypted data and its encrypted random key are stored alongside
>   - This blob can now be safely stored in non-volatile memory
> 
> On next power-on:
>   - blob is loaded into CAAM
>   - CAAM writes decrypted data either into memory or key register
> 
> Add functions to realize encrypting and decrypting into memory alongside
> the CAAM driver.
> 
> They will be used in a later commit as a source for the trusted key seal/unseal
> mechanism.
> 
> 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>
> Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
> v5 -> v6:
>   - Dropped caam_blob_alloc_desc() in favor of kzalloc() with fixed size.
>     This simplifies code and wastes at most 12 bytes which are freed
>     at the end of the function anyway.
>   - Factored out common code between caam_encap_blob and
> caam_decap_blob

Suggest to continue to use two separate descriptor-creation-function for 'encap' and 'decap'.
This will help these API(s) to be maintained easily going forward. 

>     as both functions were largely identical
>   - use append_seq_(in|out)_ptr_intlen for both encap/decap as a result
>   - use reverse christmas tree order for caam_process_blob variable
>     definitions.
> v4 -> v5:
>   - Collected Reviewed-by's and Tested-by's
>   - Note in CAAM patch what CAAM is (Jarkko)
> v3 -> v4:
>   - Collected Acked-by's, Reviewed-by's and Tested-by
>   - Fixed typo spotted by David
> v2 -> v3:
>  - No change
> v1 -> v2:
>  - Enforce maximum keymod size (Horia)
>  - Use append_seq_(in|out)_ptr_intlen instead of append_seq_(in|out)_ptr
>    (Horia)
>  - Make blobifier handle private to CAAM glue code file (Horia)
> 
> To: "Horia Geantă" <horia.geanta@nxp.com>
> To: Pankaj Gupta <pankaj.gupta@nxp.com>
> To: Herbert Xu <herbert@gondor.apana.org.au>
> To: "David S. Miller" <davem@davemloft.net>
> Cc: James Bottomley <jejb@linux.ibm.com>
> Cc: Jarkko Sakkinen <jarkko@kernel.org>
> Cc: Mimi Zohar <zohar@linux.ibm.com>
> Cc: David Howells <dhowells@redhat.com>
> Cc: James Morris <jmorris@namei.org>
> Cc: Eric Biggers <ebiggers@kernel.org>
> Cc: "Serge E. Hallyn" <serge@hallyn.com>
> 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: linux-integrity@vger.kernel.org
> Cc: keyrings@vger.kernel.org
> Cc: linux-crypto@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-security-module@vger.kernel.org
> ---
>  drivers/crypto/caam/Kconfig    |   3 +
>  drivers/crypto/caam/Makefile   |   1 +
>  drivers/crypto/caam/blob_gen.c | 160
> +++++++++++++++++++++++++++++++++
>  include/soc/fsl/caam-blob.h    |  79 ++++++++++++++++
>  4 files changed, 243 insertions(+)
>  create mode 100644 drivers/crypto/caam/blob_gen.c  create mode 100644
> include/soc/fsl/caam-blob.h
> 
> diff --git a/drivers/crypto/caam/Kconfig b/drivers/crypto/caam/Kconfig
> index 84ea7cba5ee5..ea9f8b1ae981 100644
> --- a/drivers/crypto/caam/Kconfig
> +++ b/drivers/crypto/caam/Kconfig
> @@ -151,6 +151,9 @@ config CRYPTO_DEV_FSL_CAAM_RNG_API
>           Selecting this will register the SEC4 hardware rng to
>           the hw_random API for supplying the kernel entropy pool.
> 
> +config CRYPTO_DEV_FSL_CAAM_BLOB_GEN
> +       bool
> +
>  endif # CRYPTO_DEV_FSL_CAAM_JR
> 
>  endif # CRYPTO_DEV_FSL_CAAM
> diff --git a/drivers/crypto/caam/Makefile b/drivers/crypto/caam/Makefile
> index 3570286eb9ce..25f7ae5a4642 100644
> --- a/drivers/crypto/caam/Makefile
> +++ b/drivers/crypto/caam/Makefile
> @@ -21,6 +21,7 @@ caam_jr-
> $(CONFIG_CRYPTO_DEV_FSL_CAAM_CRYPTO_API_QI) += caamalg_qi.o
>  caam_jr-$(CONFIG_CRYPTO_DEV_FSL_CAAM_AHASH_API) += caamhash.o
>  caam_jr-$(CONFIG_CRYPTO_DEV_FSL_CAAM_RNG_API) += caamrng.o
>  caam_jr-$(CONFIG_CRYPTO_DEV_FSL_CAAM_PKC_API) += caampkc.o
> pkc_desc.o
> +caam_jr-$(CONFIG_CRYPTO_DEV_FSL_CAAM_BLOB_GEN) += blob_gen.o
> 
>  caam-$(CONFIG_CRYPTO_DEV_FSL_CAAM_CRYPTO_API_QI) += qi.o  ifneq
> ($(CONFIG_CRYPTO_DEV_FSL_CAAM_CRYPTO_API_QI),)
> diff --git a/drivers/crypto/caam/blob_gen.c
> b/drivers/crypto/caam/blob_gen.c new file mode 100644 index
> 000000000000..2564e63c8fe0
> --- /dev/null
> +++ b/drivers/crypto/caam/blob_gen.c
> @@ -0,0 +1,160 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2015 Pengutronix, Steffen Trumtrar
> +<kernel@pengutronix.de>
> + * Copyright (C) 2021 Pengutronix, Ahmad Fatoum <kernel@pengutronix.de>
> +*/
> +
> +#include <linux/device.h>
> +#include <soc/fsl/caam-blob.h>
> +
> +#include "compat.h"
> +#include "desc_constr.h"
> +#include "desc.h"
> +#include "error.h"
> +#include "intern.h"
> +#include "jr.h"
> +#include "regs.h"
> +
> +/* header + (key mod immediate) + 2x seq_intlen pointers + op */
> +#define CAAM_BLOB_DESC_BYTES_MAX \
> +       (CAAM_CMD_SZ + \
> +        CAAM_CMD_SZ + CAAM_BLOB_KEYMOD_LENGTH + \
> +        2 * (CAAM_CMD_SZ + CAAM_PTR_SZ_MAX) + \
> +        CAAM_CMD_SZ)
> +
> +struct caam_blob_priv {
> +       struct device jrdev;
> +};
> +
> +struct caam_blob_job_result {
> +       int err;
> +       struct completion completion;
> +};
> +
> +static void caam_blob_job_done(struct device *dev, u32 *desc, u32 err,
> +void *context) {
> +       struct caam_blob_job_result *res = context;
> +       int ecode = 0;
> +
> +       dev_dbg(dev, "%s %d: err 0x%x\n", __func__, __LINE__, err);
> +
> +       if (err)
> +               ecode = caam_jr_strstatus(dev, err);
> +
> +       res->err = ecode;
> +
> +       /*
> +        * Upon completion, desc points to a buffer containing a CAAM job
> +        * descriptor which encapsulates data into an externally-storable
> +        * blob.
> +        */
> +       complete(&res->completion);
> +}
> +
> +int caam_process_blob(struct caam_blob_priv *priv, bool encap,
> +                     const char *keymod, void *input, void *output,
> +                     size_t length)
> +{
> +       size_t in_len = length, out_len = length;
> +       struct caam_blob_job_result testres;
> +       struct device *jrdev = &priv->jrdev;
> +       dma_addr_t dma_in, dma_out;
> +       int op = OP_PCLID_BLOB;
> +       size_t keymod_len;
> +       u32 *desc;
> +       int ret;
> +
> +       keymod_len = strlen(keymod);
> +
> +       if (length <= CAAM_BLOB_OVERHEAD || keymod_len >
> CAAM_BLOB_KEYMOD_LENGTH)
> +               return -EINVAL;
> +
> +       if (encap) {
> +               op |= OP_TYPE_ENCAP_PROTOCOL;
> +               in_len -= CAAM_BLOB_OVERHEAD;
> +       } else {
> +               op |= OP_TYPE_DECAP_PROTOCOL;
> +               out_len -= CAAM_BLOB_OVERHEAD;
> +       }
> +
> +       desc = kzalloc(CAAM_BLOB_DESC_BYTES_MAX, GFP_KERNEL |
> GFP_DMA);
> +       if (!desc) {
> +               dev_err(jrdev, "unable to allocate desc\n");
> +               return -ENOMEM;
> +       }
> +
> +       dma_in = dma_map_single(jrdev, input, in_len, DMA_TO_DEVICE);
> +       if (dma_mapping_error(jrdev, dma_in)) {
> +               dev_err(jrdev, "unable to map input DMA buffer\n");
> +               ret = -ENOMEM;
> +               goto out_free;
> +       }
> +
> +       dma_out = dma_map_single(jrdev, output, out_len,
> DMA_FROM_DEVICE);
> +       if (dma_mapping_error(jrdev, dma_out)) {
> +               dev_err(jrdev, "unable to map output DMA buffer\n");
> +               ret = -ENOMEM;
> +               goto out_unmap_in;
> +       }
> +
> +       /*
> +        * A data blob is encrypted using a blob key (BK); a random number.
> +        * The BK is used as an AES-CCM key. The initial block (B0) and the
> +        * initial counter (Ctr0) are generated automatically and stored in
> +        * Class 1 Context DWords 0+1+2+3. The random BK is stored in the
> +        * Class 1 Key Register. Operation Mode is set to AES-CCM.
> +        */
> +
> +       init_job_desc(desc, 0);
> +       append_key_as_imm(desc, keymod, keymod_len, keymod_len,
> +                         CLASS_2 | KEY_DEST_CLASS_REG);
> +       append_seq_in_ptr_intlen(desc, dma_in, in_len, 0);
> +       append_seq_out_ptr_intlen(desc, dma_out, out_len, 0);
> +       append_operation(desc, op);
> +
> +       print_hex_dump_debug("data@"__stringify(__LINE__)": ",
> +                            DUMP_PREFIX_ADDRESS, 16, 1, input,
> +                            in_len, false);
> +       print_hex_dump_debug("jobdesc@"__stringify(__LINE__)": ",
> +                            DUMP_PREFIX_ADDRESS, 16, 1, desc,
> +                            desc_bytes(desc), false);
> +
> +       testres.err = 0;
> +       init_completion(&testres.completion);
> +
> +       ret = caam_jr_enqueue(jrdev, desc, caam_blob_job_done, &testres);
> +       if (ret == -EINPROGRESS) {
> +               wait_for_completion(&testres.completion);
> +               ret = testres.err;
> +               print_hex_dump_debug("output@"__stringify(__LINE__)": ",
> +                                    DUMP_PREFIX_ADDRESS, 16, 1, output,
> +                                    out_len, false);
> +       }
> +
> +       dma_unmap_single(jrdev, dma_out, out_len, DMA_FROM_DEVICE);
> +out_unmap_in:
> +       dma_unmap_single(jrdev, dma_in, in_len, DMA_TO_DEVICE);
> +out_free:
> +       kfree(desc);
> +
> +       return ret;
> +}
> +EXPORT_SYMBOL(caam_process_blob);
> +
> +struct caam_blob_priv *caam_blob_gen_init(void) {
> +       struct device *jrdev;
> +
> +       jrdev = caam_jr_alloc();
> +       if (IS_ERR(jrdev))
> +               return ERR_CAST(jrdev);
> +
> +       return container_of(jrdev, struct caam_blob_priv, jrdev); }
> +EXPORT_SYMBOL(caam_blob_gen_init);
> +
> +void caam_blob_gen_exit(struct caam_blob_priv *priv) {
> +       caam_jr_free(&priv->jrdev);
> +}
> +EXPORT_SYMBOL(caam_blob_gen_exit);
> diff --git a/include/soc/fsl/caam-blob.h b/include/soc/fsl/caam-blob.h new
> file mode 100644 index 000000000000..2c4a05dc59cd
> --- /dev/null
> +++ b/include/soc/fsl/caam-blob.h
> @@ -0,0 +1,79 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2020 Pengutronix, Ahmad Fatoum <kernel@pengutronix.de>
> +*/
> +
> +#ifndef __CAAM_BLOB_GEN
> +#define __CAAM_BLOB_GEN
> +
> +#include <linux/types.h>
> +
> +#define CAAM_BLOB_KEYMOD_LENGTH                16
> +#define CAAM_BLOB_OVERHEAD             (32 + 16)
> +#define CAAM_BLOB_MAX_LEN              4096
> +
> +struct caam_blob_priv;
> +
> +/** caam_blob_gen_init - initialize blob generation
> + *
> + * returns either pointer to new caam_blob_priv instance
> + * or error pointer
> + */
> +struct caam_blob_priv *caam_blob_gen_init(void);
> +
> +/** caam_blob_gen_exit - free blob generation resources
> + *
> + * @priv: instance returned by caam_blob_gen_init  */ void
> +caam_blob_gen_exit(struct caam_blob_priv *priv);
> +
> +/** caam_process_blob - encapsulate or decapsulate blob
> + *
> + * @priv:   instance returned by caam_blob_gen_init
> + * @encap:  true for encapsulation, false for decapsulation
> + * @keymod: string to use as key modifier for blob capsulation
> + *         can't be longer than CAAM_BLOB_KEYMOD_LENGTH
> + * @input:  buffer which CAAM will DMA from
> + * @output: buffer which CAAM will DMA to
> + * @length: buffer length including blob overhead
> + *          CAAM_BLOB_OVERHEAD < length <= CAAM_BLOB_MAX_LEN
> + */
> +int caam_process_blob(struct caam_blob_priv *priv, bool encap,
> +                     const char *keymod, void *input, void *output,
> +                     size_t length);
> +
> +/** caam_encap_blob - encapsulate blob
> + *
> + * @priv:   instance returned by caam_blob_gen_init
> + * @keymod: string to use as key modifier for blob encapsulation
> + *         can't be longer than CAAM_BLOB_KEYMOD_LENGTH
> + * @input:  buffer which CAAM will DMA from
> + * @output: buffer which CAAM will DMA to
> + * @length: buffer length including blob overhead
> + *          CAAM_BLOB_OVERHEAD < length <= CAAM_BLOB_MAX_LEN
> + */
> +static inline int caam_encap_blob(struct caam_blob_priv *priv,
> +                                 const char *keymod,
> +                                 void *input, void *output, size_t
> +length) {
> +       return caam_process_blob(priv, true, keymod, input, output,
> +length); }
> +

In continuation to the previous comment, there is another suggestion:

Either: 
struct keyblob_info {
        void *key;
        size_t key_len;

        void *blob;
        size_t blob_len;

        size_t key_mod_len;
        const void *key_mod;
};

Or:

struct keyblob_info {        
        void *input;
        void *input_len;

        void *output;
        void *out_len;

        size_t key_mod_len;
        const void *key_mod;
};


int caam_blob_encap(struct caam_blob_priv *priv, struct keyblob_info *info);

int caam_blob_decap(struct caam_blob_priv *priv, struct keyblob_info *info);

> +/** caam_decap_blob - decapsulate blob
> + *
> + * @priv:   instance returned by caam_blob_gen_init
> + * @keymod: string to use as key modifier for blob decapsulation
> + *         can't be longer than CAAM_BLOB_KEYMOD_LENGTH
> + * @input:  buffer which CAAM will DMA from
> + * @output: buffer which CAAM will DMA to
> + * @length: buffer length including blob overhead
> + *          CAAM_BLOB_OVERHEAD < length <= CAAM_BLOB_MAX_LEN
> + */
> +static inline int caam_decap_blob(struct caam_blob_priv *priv,
> +                                 const char *keymod,
> +                                 void *input, void *output, size_t
> +length) {
> +       return caam_process_blob(priv, false, keymod, input, output,
> +length); }
> +
> +#endif
> --
> 2.30.2