Re: [PATCH v7 3/6] crypto: caam - add in-kernel interface for blob generator

[Jarkko Sakkinen <jarkko@kernel.org>]

On Fri, 2022-04-15 at 22:56 +0200, Ahmad Fatoum wrote:
> 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>
> ---
> v6 -> v7:
>   - Added more verbose comment on how CAAM_BLOB_DESC_BYTES_MAX adds up.
>   - remove error message on kzalloc failure (checkpatch)
>   - Replaced buffer arguments with structure containing them (Pankaj)
> 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
>     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 | 164 +++++++++++++++++++++++++++++++++
>  include/soc/fsl/caam-blob.h    | 102 ++++++++++++++++++++
>  4 files changed, 270 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..f166937fcfeb
> --- /dev/null
> +++ b/drivers/crypto/caam/blob_gen.c
> @@ -0,0 +1,164 @@
> +// 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"
> +
> +#define CAAM_BLOB_DESC_BYTES_MAX                                       \
> +       /* Command to initialize & stating length of descriptor */      \
> +       (CAAM_CMD_SZ +                                                  \
> +       /* Command to append the key-modifier + key-modifier data */    \
> +        CAAM_CMD_SZ + CAAM_BLOB_KEYMOD_LENGTH +                        \
> +       /* Command to include input key + pointer to the input key */   \
> +        CAAM_CMD_SZ + CAAM_PTR_SZ_MAX +                                \
> +       /* Command to include output key + pointer to the output key */ \
> +        CAAM_CMD_SZ + CAAM_PTR_SZ_MAX +                                \
> +       /* Command describing the Operation to perform */               \
> +        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,
> +                     struct caam_blob_info *info, bool encap)

Documentation missing (it's exported).

> +{
> +       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 output_len;
> +       u32 *desc;
> +       int ret;
> +
> +       if (info->key_mod_len > CAAM_BLOB_KEYMOD_LENGTH)
> +               return -EINVAL;
> +
> +       if (encap) {
> +               op |= OP_TYPE_ENCAP_PROTOCOL;
> +               output_len = info->input_len + CAAM_BLOB_OVERHEAD;
> +       } else {
> +               op |= OP_TYPE_DECAP_PROTOCOL;
> +               output_len = info->input_len - CAAM_BLOB_OVERHEAD;
> +       }
> +
> +       desc = kzalloc(CAAM_BLOB_DESC_BYTES_MAX, GFP_KERNEL | GFP_DMA);
> +       if (!desc)
> +               return -ENOMEM;
> +
> +       dma_in = dma_map_single(jrdev, info->input, info->input_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, info->output, output_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, info->key_mod, info->key_mod_len,
> +                         info->key_mod_len, CLASS_2 | KEY_DEST_CLASS_REG);
> +       append_seq_in_ptr_intlen(desc, dma_in, info->input_len, 0);
> +       append_seq_out_ptr_intlen(desc, dma_out, output_len, 0);
> +       append_operation(desc, op);
> +
> +       print_hex_dump_debug("data@"__stringify(__LINE__)": ",
> +                            DUMP_PREFIX_ADDRESS, 16, 1, info->input,
> +                            info->input_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, info->output,
> +                                    output_len, false);
> +       }
> +
> +       if (ret == 0)
> +               info->output_len = output_len;
> +
> +       dma_unmap_single(jrdev, dma_out, output_len, DMA_FROM_DEVICE);
> +out_unmap_in:
> +       dma_unmap_single(jrdev, dma_in, info->input_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..0be0ab2da5c7
> --- /dev/null
> +++ b/include/soc/fsl/caam-blob.h
> @@ -0,0 +1,102 @@
> +/* 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>
> +#include <linux/errno.h>
> +
> +#define CAAM_BLOB_KEYMOD_LENGTH                16
> +#define CAAM_BLOB_OVERHEAD             (32 + 16)
> +#define CAAM_BLOB_MAX_LEN              4096
> +
> +struct caam_blob_priv;
> +
> +/** struct caam_blob_info - information for CAAM blobbing
> + *

You can remove this extra line, applies to some functions in the patch
too.

> + * @input:       pointer to input buffer (must be DMAable)
> + * @input_len:   length of @input buffer in bytes.
> + * @output:      pointer to output buffer (must be DMAable)
> + * @output_len:  length of @output buffer in bytes.
> + * @key_mod:     key modifier
> + * @key_mod_len: length of @key_mod in bytes.
> + *              May not exceed CAAM_BLOB_KEYMOD_LENGTH
> + */
> +struct caam_blob_info {
> +       void *input;
> +       size_t input_len;
> +
> +       void *output;
> +       size_t output_len;
> +
> +       const void *key_mod;
> +       size_t key_mod_len;
> +};
> +
> +/** 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
> + * @info:   pointer to blobbing info describing key, blob and
> + *          key modifier buffers.
> + * @encap:  true for encapsulation, false for decapsulation
> + *
> + * returns 0 and sets info->output_len on success and returns
> + * a negative error code otherwise.
> + */
> +int caam_process_blob(struct caam_blob_priv *priv,
> +                     struct caam_blob_info *info, bool blob);
> +
> +/** caam_encap_blob - encapsulate blob
> + *
> + * @priv:   instance returned by caam_blob_gen_init
> + * @info:   pointer to blobbing info describing input key,
> + *          output blob and key modifier buffers.
> + *
> + * returns 0 and sets info->output_len on success and returns
> + * a negative error code otherwise.
> + */
> +static inline int caam_encap_blob(struct caam_blob_priv *priv,
> +                                 struct caam_blob_info *info)
> +{
> +       if (info->output_len < info->input_len + CAAM_BLOB_OVERHEAD)
> +               return -EINVAL;
> +
> +       return caam_process_blob(priv, info, true);
> +}
> +
> +/** caam_decap_blob - decapsulate blob
> + *
> + * @priv:   instance returned by caam_blob_gen_init
> + * @info:   pointer to blobbing info describing output key,
> + *          input blob and key modifier buffers.
> + *
> + * returns 0 and sets info->output_len on success and returns
> + * a negative error code otherwise.
> + */
> +static inline int caam_decap_blob(struct caam_blob_priv *priv,
> +                                 struct caam_blob_info *info)
> +{
> +       if (info->input_len < CAAM_BLOB_OVERHEAD ||
> +           info->output_len < info->input_len - CAAM_BLOB_OVERHEAD)
> +               return -EINVAL;
> +
> +       return caam_process_blob(priv, info, false);
> +}
> +
> +#endif

BR, Jarkko