Re: [PATCH v4 4/5] crypto: caam - add in-kernel interface for blob generator

From: Ahmad Fatoum
Date: Mon Nov 01 2021 - 04:00:57 EST

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Hello Horia, Aymen,

On 11.10.21 12:02, Ahmad Fatoum wrote:
> The 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.

Did you have time to look at this again?

I have incorporated the changes request in v1 and the
code has since been reviewed and tested by others.

Thanks,
Ahmad

> Reviewed-by: David Gstir <david@xxxxxxxxxxxxx>
> Tested-By: Tim Harvey <tharvey@xxxxxxxxxxxxx>
> Signed-off-by: Steffen Trumtrar <s.trumtrar@xxxxxxxxxxxxxx>
> Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
> ---
> To: "Horia Geantă" <horia.geanta@xxxxxxx>
> To: Aymen Sghaier <aymen.sghaier@xxxxxxx>
> To: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> To: "David S. Miller" <davem@xxxxxxxxxxxxx>
> Cc: James Bottomley <jejb@xxxxxxxxxxxxx>
> Cc: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
> Cc: Mimi Zohar <zohar@xxxxxxxxxxxxx>
> Cc: David Howells <dhowells@xxxxxxxxxx>
> Cc: James Morris <jmorris@xxxxxxxxx>
> Cc: Eric Biggers <ebiggers@xxxxxxxxxx>
> Cc: "Serge E. Hallyn" <serge@xxxxxxxxxx>
> Cc: Udit Agarwal <udit.agarwal@xxxxxxx>
> Cc: Jan Luebbe <j.luebbe@xxxxxxxxxxxxxx>
> Cc: David Gstir <david@xxxxxxxxxxxxx>
> Cc: Richard Weinberger <richard@xxxxxx>
> Cc: Franck LENORMAND <franck.lenormand@xxxxxxx>
> Cc: Sumit Garg <sumit.garg@xxxxxxxxxx>
> Cc: linux-integrity@xxxxxxxxxxxxxxx
> Cc: keyrings@xxxxxxxxxxxxxxx
> Cc: linux-crypto@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: linux-security-module@xxxxxxxxxxxxxxx
> ---
> drivers/crypto/caam/Kconfig | 3 +-
> drivers/crypto/caam/Makefile | 1 +-
> drivers/crypto/caam/blob_gen.c | 230 ++++++++++++++++++++++++++++++++++-
> include/soc/fsl/caam-blob.h | 56 ++++++++-
> 4 files changed, 290 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..513d3f90e438
> --- /dev/null
> +++ b/drivers/crypto/caam/blob_gen.c
> @@ -0,0 +1,230 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2015 Pengutronix, Steffen Trumtrar <kernel@xxxxxxxxxxxxxx>
> + * Copyright (C) 2021 Pengutronix, Ahmad Fatoum <kernel@xxxxxxxxxxxxxx>
> + */
> +
> +#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"
> +
> +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);
> +}
> +
> +static u32 *caam_blob_alloc_desc(size_t keymod_len)
> +{
> + size_t len;
> +
> + /* header + (key mod immediate) + 2x pointers + op */
> + len = 4 + (4 + ALIGN(keymod_len, 4)) + 2*(4 + 4 + CAAM_PTR_SZ_MAX) + 4;
> +
> + if (len > CAAM_DESC_BYTES_MAX)
> + return NULL;
> +
> + return kzalloc(len, GFP_KERNEL | GFP_DMA);
> +}
> +
> +int caam_encap_blob(struct caam_blob_priv *priv, const char *keymod,
> + void *input, void *output, size_t length)
> +{
> + u32 *desc;
> + struct device *jrdev = &priv->jrdev;
> + dma_addr_t dma_in, dma_out;
> + struct caam_blob_job_result testres;
> + size_t keymod_len = strlen(keymod);
> + int ret;
> +
> + if (length <= CAAM_BLOB_OVERHEAD || keymod_len > CAAM_BLOB_KEYMOD_LENGTH)
> + return -EINVAL;
> +
> + desc = caam_blob_alloc_desc(keymod_len);
> + if (!desc) {
> + dev_err(jrdev, "unable to allocate desc\n");
> + return -ENOMEM;
> + }
> +
> + dma_in = dma_map_single(jrdev, input, length - CAAM_BLOB_OVERHEAD, 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, length, 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, length - CAAM_BLOB_OVERHEAD, 0);
> + append_seq_out_ptr_intlen(desc, dma_out, length, 0);
> + append_operation(desc, OP_TYPE_ENCAP_PROTOCOL | OP_PCLID_BLOB);
> +
> + print_hex_dump_debug("data@"__stringify(__LINE__)": ",
> + DUMP_PREFIX_ADDRESS, 16, 1, input,
> + length - CAAM_BLOB_OVERHEAD, 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,
> + length, false);
> + }
> +
> + dma_unmap_single(jrdev, dma_out, length, DMA_FROM_DEVICE);
> +out_unmap_in:
> + dma_unmap_single(jrdev, dma_in, length - CAAM_BLOB_OVERHEAD, DMA_TO_DEVICE);
> +out_free:
> + kfree(desc);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL(caam_encap_blob);
> +
> +int caam_decap_blob(struct caam_blob_priv *priv, const char *keymod,
> + void *input, void *output, size_t length)
> +{
> + u32 *desc;
> + struct device *jrdev = &priv->jrdev;
> + dma_addr_t dma_in, dma_out;
> + struct caam_blob_job_result testres;
> + size_t keymod_len = strlen(keymod);
> + int ret;
> +
> + if (length <= CAAM_BLOB_OVERHEAD || keymod_len > CAAM_BLOB_KEYMOD_LENGTH)
> + return -EINVAL;
> +
> + desc = caam_blob_alloc_desc(keymod_len);
> + if (!desc) {
> + dev_err(jrdev, "unable to allocate desc\n");
> + return -ENOMEM;
> + }
> +
> + dma_in = dma_map_single(jrdev, input, length, 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, length - CAAM_BLOB_OVERHEAD, 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(desc, dma_in, length, 0);
> + append_seq_out_ptr(desc, dma_out, length - CAAM_BLOB_OVERHEAD, 0);
> + append_operation(desc, OP_TYPE_DECAP_PROTOCOL | OP_PCLID_BLOB);
> +
> + print_hex_dump_debug("data@"__stringify(__LINE__)": ",
> + DUMP_PREFIX_ADDRESS, 16, 1, input,
> + length, 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,
> + length - CAAM_BLOB_OVERHEAD, false);
> + }
> +
> + dma_unmap_single(jrdev, dma_out, length - CAAM_BLOB_OVERHEAD, DMA_FROM_DEVICE);
> +out_unmap_in:
> + dma_unmap_single(jrdev, dma_in, length, DMA_TO_DEVICE);
> +out_free:
> + kfree(desc);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL(caam_decap_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..83fd990ebdce
> --- /dev/null
> +++ b/include/soc/fsl/caam-blob.h
> @@ -0,0 +1,56 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2020 Pengutronix, Ahmad Fatoum <kernel@xxxxxxxxxxxxxx>
> + */
> +
> +#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_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
> + */
> +int caam_encap_blob(struct caam_blob_priv *priv, const char *keymod,
> + void *input, void *output, size_t length);
> +
> +/** 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
> + */
> +int caam_decap_blob(struct caam_blob_priv *priv, const char *keymod,
> + void *input, void *output, size_t length);
> +
> +#endif
>

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