[PATCH v10 4/7] crypto: caam - add in-kernel interface for blob generator

Ahmad Fatoum
2022-05-13T14:58:32Z

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>
Tested-by: Pankaj Gupta <pankaj.gupta@nxp.com>
Tested-by: Michael Walle <michael@walle.cc> # on ls1028a (non-E and E)
Tested-by: John Ernberg <john.ernberg@actia.se> # iMX8QXP
Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
v9 -> v10:
- added Michael's and John's Tested-by
v8 -> v9:
- Improve kernel-doc with ``literal`` formatting and &struct/func()
references
- Have caam_blob_gen_init return -ENODEV in absence of job ring
or blobbing support with appropriate info messages
v7 -> v8:
- remove unneeded new line in kernel doc (Jarkko)
- Make comments parse as kernel-doc and fix associated warnings
- add Pankaj's Tested-by
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: Michael Walle <michael@walle.cc>
Cc: John Ernberg <john.ernberg@actia.se>
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 | 182 +++++++++++++++++++++++++++++++++
include/soc/fsl/caam-blob.h | 103 +++++++++++++++++++
4 files changed, 289 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..6345c7269eb0
--- /dev/null
+++ b/drivers/crypto/caam/blob_gen.c
@@ -0,0 +1,182 @@
+// 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>
+ */
+
+#define pr_fmt(fmt) "caam blob_gen: " fmt
+
+#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)
+{
+ 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 caam_drv_private *ctrlpriv;
+ struct device *jrdev;
+
+ /*
+ * caam_blob_gen_init() may expectedly fail with -ENODEV, e.g. when
+ * CAAM driver didn't probe or when SoC lacks BLOB support. An
+ * error would be harsh in this case, so we stick to info level.
+ */
+
+ jrdev = caam_jr_alloc();
+ if (IS_ERR(jrdev)) {
+ pr_info("job ring requested, but none currently available\n");
+ return ERR_PTR(-ENODEV);
+ }
+
+ ctrlpriv = dev_get_drvdata(jrdev->parent);
+ if (!ctrlpriv->blob_present) {
+ dev_info(jrdev, "no hardware blob generation support\n");
+ caam_jr_free(jrdev);
+ return ERR_PTR(-ENODEV);
+ }
+
+ 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..937cac52f36d
--- /dev/null
+++ b/include/soc/fsl/caam-blob.h
@@ -0,0 +1,103 @@
+/* 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
+ * @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
+ * Return: pointer to new &struct caam_blob_priv instance on success
+ * and ``ERR_PTR(-ENODEV)`` if CAAM has no hardware blobbing support
+ * or no job ring could be allocated.
+ */
+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
+ *
+ * Return: %0 and sets ``info->output_len`` on success and a negative
+ * error code otherwise.
+ */
+int caam_process_blob(struct caam_blob_priv *priv,
+ struct caam_blob_info *info, bool encap);
+
+/**
+ * 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.
+ *
+ * Return: %0 and sets ``info->output_len`` on success and
+ * 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.
+ *
+ * Return: %0 and sets ``info->output_len`` on success and
+ * 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
--
2.30.2