diff mbox series

[v1,1/3] crypto: caam - add in-kernel interface for blob generator

Message ID 420d2319e533ac97965fb826a70bdb023af2a844.1615914058.git-series.a.fatoum@pengutronix.de
State Superseded
Headers show
Series [v1,1/3] crypto: caam - add in-kernel interface for blob generator | expand

Commit Message

Ahmad Fatoum March 16, 2021, 5:01 p.m. UTC 
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.

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
To: "Horia Geantă" <horia.geanta@nxp.com>
To: Aymen Sghaier <aymen.sghaier@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: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Udit Agarwal <udit.agarwal@nxp.com>
Cc: Jan Luebbe <j.luebbe@penutronix.de>
Cc: David Gstir <david@sigma-star.at>
Cc: Franck LENORMAND <franck.lenormand@nxp.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    |   4 +-
 drivers/crypto/caam/Makefile   |   1 +-
 drivers/crypto/caam/blob_gen.c | 230 ++++++++++++++++++++++++++++++++++-
 include/soc/fsl/caam-blob.h    |  54 ++++++++-
 4 files changed, 289 insertions(+)
 create mode 100644 drivers/crypto/caam/blob_gen.c
 create mode 100644 include/soc/fsl/caam-blob.h

Comments

Horia Geanta March 21, 2021, 8:46 p.m. UTC | #1 
On 3/16/2021 7:01 PM, Ahmad Fatoum wrote:
> +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)

> +		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(desc, dma_in, length - CAAM_BLOB_OVERHEAD, 0);

> +	append_seq_out_ptr(desc, dma_out, length, 0);

In case length is known to be < 2^16, it's recommended to use instead
append_seq_in_ptr_intlen, append_seq_out_ptr_intlen.

> +	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);

> +

[...]
> diff --git a/include/soc/fsl/caam-blob.h b/include/soc/fsl/caam-blob.h

> new file mode 100644

> index 000000000000..7eea0f543832

> --- /dev/null

> +++ b/include/soc/fsl/caam-blob.h

> @@ -0,0 +1,54 @@

> +/* 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

The define isn't used here or on patch 3/3.

> +#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_init - 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

> + * @input:  buffer which CAAM will DMA from

> + * @output: buffer which CAAM will DMA to

Is it guaranteed that input, output can be DMA-mapped?

Horia
Ahmad Fatoum March 23, 2021, 4:41 p.m. UTC | #2 
Hello Horia,

On 21.03.21 21:46, Horia Geantă wrote:
> On 3/16/2021 7:01 PM, Ahmad Fatoum wrote:

>> +	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 - CAAM_BLOB_OVERHEAD, 0);

>> +	append_seq_out_ptr(desc, dma_out, length, 0);

> In case length is known to be < 2^16, it's recommended to use instead

> append_seq_in_ptr_intlen, append_seq_out_ptr_intlen.


Didn't know about this one. Will look into using it for v2.

>> +#define CAAM_BLOB_KEYMOD_LENGTH		16

> The define isn't used here or on patch 3/3.


Will drop and adjust the function docs to note the maximum modifier length.


>> +#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_init - 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

>> + * @input:  buffer which CAAM will DMA from

>> + * @output: buffer which CAAM will DMA to

> Is it guaranteed that input, output can be DMA-mapped?


It's expected callers ensure that this is the case. Trusted key buffers
are allocated with kmalloc and can be DMA-mapped.

Thanks for the review,
Ahmad

-- 
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diff mbox series

Patch

diff --git a/drivers/crypto/caam/Kconfig b/drivers/crypto/caam/Kconfig
index 84ea7cba5ee5..8f7df1299f3d 100644
--- a/drivers/crypto/caam/Kconfig
+++ b/drivers/crypto/caam/Kconfig
@@ -151,6 +151,10 @@  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
+	default y if TRUSTED_KEYS
+
 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..21e83ad0f226 100644
--- a/drivers/crypto/caam/Makefile
+++ b/drivers/crypto/caam/Makefile
@@ -13,6 +13,7 @@  obj-$(CONFIG_CRYPTO_DEV_FSL_CAAM) += caam.o
 obj-$(CONFIG_CRYPTO_DEV_FSL_CAAM_JR) += caam_jr.o
 obj-$(CONFIG_CRYPTO_DEV_FSL_CAAM_CRYPTO_API_DESC) += caamalg_desc.o
 obj-$(CONFIG_CRYPTO_DEV_FSL_CAAM_AHASH_API_DESC) += caamhash_desc.o
+obj-$(CONFIG_CRYPTO_DEV_FSL_CAAM_BLOB_GEN) += blob_gen.o
 
 caam-y := ctrl.o
 caam_jr-y := jr.o key_gen.o
diff --git a/drivers/crypto/caam/blob_gen.c b/drivers/crypto/caam/blob_gen.c
new file mode 100644
index 000000000000..6a17941c9504
--- /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@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"
+
+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)
+		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(desc, dma_in, length - CAAM_BLOB_OVERHEAD, 0);
+	append_seq_out_ptr(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)
+		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..7eea0f543832
--- /dev/null
+++ b/include/soc/fsl/caam-blob.h
@@ -0,0 +1,54 @@ 
+/* 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_init - 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
+ * @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
+ * @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