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

Ahmad Fatoum
2021-10-11T10:03:49Z

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.

Reviewed-by: David Gstir <david@sigma-star.at>
Tested-By: Tim Harvey <tharvey@gateworks.com>
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: Eric Biggers <ebiggers@kernel.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Udit Agarwal <udit.agarwal@nxp.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: 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 | 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@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 || 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@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_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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