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

[Ahmad Fatoum]

Hello again,

On 01.11.21 09:00, Ahmad Fatoum wrote:
> 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?

Ping.

> 
> 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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