2022-04-29 09:37:07

by Meenakshi Aggarwal

[permalink] [raw]
Subject: [PATCH v4 1/1] crypto: caam/rng: Add support for PRNG

From: Meenakshi Aggarwal <[email protected]>

Add support for random number generation using PRNG
mode of CAAM and expose the interface through crypto API.

According to the RM, the HW implementation of the DRBG follows
NIST SP 800-90A specification for DRBG_Hash SHA-256 function

Signed-off-by: Meenakshi Aggarwal <[email protected]>
---
drivers/crypto/caam/Kconfig | 8 ++
drivers/crypto/caam/Makefile | 1 +
drivers/crypto/caam/caamprng.c | 234 +++++++++++++++++++++++++++++++++
drivers/crypto/caam/intern.h | 15 +++
drivers/crypto/caam/jr.c | 3 +-
5 files changed, 260 insertions(+), 1 deletion(-)
create mode 100644 drivers/crypto/caam/caamprng.c

diff --git a/drivers/crypto/caam/Kconfig b/drivers/crypto/caam/Kconfig
index 84ea7cba5ee5..0aa52b612a01 100644
--- a/drivers/crypto/caam/Kconfig
+++ b/drivers/crypto/caam/Kconfig
@@ -151,6 +151,14 @@ 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_PRNG_API
+ bool "Register Pseudo random number generation implementation with Crypto API"
+ default y
+ select CRYPTO_RNG
+ help
+ Selecting this will register the SEC hardware prng to
+ the Crypto API.
+
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..4f9837a8a1ad 100644
--- a/drivers/crypto/caam/Makefile
+++ b/drivers/crypto/caam/Makefile
@@ -20,6 +20,7 @@ caam_jr-$(CONFIG_CRYPTO_DEV_FSL_CAAM_CRYPTO_API) += caamalg.o
caam_jr-$(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-$(CONFIG_CRYPTO_DEV_FSL_CAAM_PRNG_API) += caamprng.o
caam_jr-$(CONFIG_CRYPTO_DEV_FSL_CAAM_PKC_API) += caampkc.o pkc_desc.o

caam-$(CONFIG_CRYPTO_DEV_FSL_CAAM_CRYPTO_API_QI) += qi.o
diff --git a/drivers/crypto/caam/caamprng.c b/drivers/crypto/caam/caamprng.c
new file mode 100644
index 000000000000..728fd8e591d0
--- /dev/null
+++ b/drivers/crypto/caam/caamprng.c
@@ -0,0 +1,234 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Driver to expose SEC4 PRNG via crypto RNG API
+ *
+ * Copyright 2022 NXP
+ *
+ */
+
+#include <linux/completion.h>
+#include <crypto/internal/rng.h>
+#include "compat.h"
+#include "regs.h"
+#include "intern.h"
+#include "desc_constr.h"
+#include "jr.h"
+#include "error.h"
+
+/*
+ * Length of used descriptors, see caam_init_desc()
+ */
+#define CAAM_PRNG_DESC_LEN (CAAM_CMD_SZ + \
+ CAAM_CMD_SZ + \
+ CAAM_CMD_SZ + CAAM_PTR_SZ_MAX)
+
+/* prng per-device context */
+struct caam_prng_ctx {
+ int err;
+ struct completion done;
+};
+
+struct caam_prng_alg {
+ struct rng_alg rng;
+ bool registered;
+};
+
+static void caam_prng_done(struct device *jrdev, u32 *desc, u32 err,
+ void *context)
+{
+ struct caam_prng_ctx *jctx = context;
+
+ jctx->err = err ? caam_jr_strstatus(jrdev, err) : 0;
+
+ complete(&jctx->done);
+}
+
+static u32 *caam_init_reseed_desc(u32 *desc)
+{
+ init_job_desc(desc, 0); /* + 1 cmd_sz */
+ /* Generate random bytes: + 1 cmd_sz */
+ append_operation(desc, OP_TYPE_CLASS1_ALG | OP_ALG_ALGSEL_RNG |
+ OP_ALG_AS_FINALIZE);
+
+ print_hex_dump_debug("prng reseed [email protected]: ", DUMP_PREFIX_ADDRESS,
+ 16, 4, desc, desc_bytes(desc), 1);
+
+ return desc;
+}
+
+static u32 *caam_init_prng_desc(u32 *desc, dma_addr_t dst_dma, u32 len)
+{
+ init_job_desc(desc, 0); /* + 1 cmd_sz */
+ /* Generate random bytes: + 1 cmd_sz */
+ append_operation(desc, OP_ALG_ALGSEL_RNG | OP_TYPE_CLASS1_ALG);
+ /* Store bytes: + 1 cmd_sz + caam_ptr_sz */
+ append_fifo_store(desc, dst_dma,
+ len, FIFOST_TYPE_RNGSTORE);
+
+ print_hex_dump_debug("prng job [email protected]: ", DUMP_PREFIX_ADDRESS,
+ 16, 4, desc, desc_bytes(desc), 1);
+
+ return desc;
+}
+
+static int caam_prng_generate(struct crypto_rng *tfm,
+ const u8 *src, unsigned int slen,
+ u8 *dst, unsigned int dlen)
+{
+ struct caam_prng_ctx ctx;
+ struct device *jrdev;
+ dma_addr_t dst_dma;
+ u32 *desc;
+ u8 *buf;
+ int ret;
+
+ buf = kzalloc(dlen, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ jrdev = caam_jr_alloc();
+ ret = PTR_ERR_OR_ZERO(jrdev);
+ if (ret) {
+ pr_err("Job Ring Device allocation failed\n");
+ kfree(buf);
+ return ret;
+ }
+
+ desc = kzalloc(CAAM_PRNG_DESC_LEN, GFP_KERNEL | GFP_DMA);
+ if (!desc) {
+ ret = -ENOMEM;
+ goto out1;
+ }
+
+ dst_dma = dma_map_single(jrdev, buf, dlen, DMA_FROM_DEVICE);
+ if (dma_mapping_error(jrdev, dst_dma)) {
+ dev_err(jrdev, "Failed to map destination buffer memory\n");
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ init_completion(&ctx.done);
+ ret = caam_jr_enqueue(jrdev,
+ caam_init_prng_desc(desc, dst_dma, dlen),
+ caam_prng_done, &ctx);
+
+ if (ret == -EINPROGRESS) {
+ wait_for_completion(&ctx.done);
+ ret = ctx.err;
+ }
+
+ dma_unmap_single(jrdev, dst_dma, dlen, DMA_FROM_DEVICE);
+
+ memcpy(dst, buf, dlen);
+out:
+ kfree(desc);
+out1:
+ caam_jr_free(jrdev);
+ kfree(buf);
+ return ret;
+}
+
+static void caam_prng_exit(struct crypto_tfm *tfm) {}
+
+static int caam_prng_init(struct crypto_tfm *tfm)
+{
+ return 0;
+}
+
+static int caam_prng_seed(struct crypto_rng *tfm,
+ const u8 *seed, unsigned int slen)
+{
+ struct caam_prng_ctx ctx;
+ struct device *jrdev;
+ u32 *desc;
+ int ret;
+
+ if (slen) {
+ pr_err("Seed length should be zero\n");
+ return -EINVAL;
+ }
+
+ jrdev = caam_jr_alloc();
+ ret = PTR_ERR_OR_ZERO(jrdev);
+ if (ret) {
+ pr_err("Job Ring Device allocation failed\n");
+ return ret;
+ }
+
+ desc = kzalloc(CAAM_PRNG_DESC_LEN, GFP_KERNEL | GFP_DMA);
+ if (!desc) {
+ caam_jr_free(jrdev);
+ return -ENOMEM;
+ }
+
+ init_completion(&ctx.done);
+ ret = caam_jr_enqueue(jrdev,
+ caam_init_reseed_desc(desc),
+ caam_prng_done, &ctx);
+
+ if (ret == -EINPROGRESS) {
+ wait_for_completion(&ctx.done);
+ ret = ctx.err;
+ }
+
+ kfree(desc);
+ caam_jr_free(jrdev);
+ return ret;
+}
+
+static struct caam_prng_alg caam_prng_alg = {
+ .rng = {
+ .generate = caam_prng_generate,
+ .seed = caam_prng_seed,
+ .seedsize = 0,
+ .base = {
+ .cra_name = "stdrng",
+ .cra_driver_name = "prng-caam",
+ .cra_priority = 500,
+ .cra_ctxsize = sizeof(struct caam_prng_ctx),
+ .cra_module = THIS_MODULE,
+ .cra_init = caam_prng_init,
+ .cra_exit = caam_prng_exit,
+ },
+ }
+};
+
+void caam_prng_unregister(void *data)
+{
+ if (caam_prng_alg.registered)
+ crypto_unregister_rng(&caam_prng_alg.rng);
+}
+
+int caam_prng_register(struct device *ctrldev)
+{
+ struct caam_drv_private *priv = dev_get_drvdata(ctrldev);
+ u32 rng_inst;
+ int ret = 0;
+
+ /* Check for available RNG blocks before registration */
+ if (priv->era < 10)
+ rng_inst = (rd_reg32(&priv->jr[0]->perfmon.cha_num_ls) &
+ CHA_ID_LS_RNG_MASK) >> CHA_ID_LS_RNG_SHIFT;
+ else
+ rng_inst = rd_reg32(&priv->jr[0]->vreg.rng) & CHA_VER_NUM_MASK;
+
+ if (!rng_inst) {
+ dev_dbg(ctrldev, "RNG block is not available... skipping registering algorithm\n");
+ return ret;
+ }
+
+ ret = crypto_register_rng(&caam_prng_alg.rng);
+ if (ret) {
+ dev_err(ctrldev,
+ "couldn't register rng crypto alg: %d\n",
+ ret);
+ return ret;
+ }
+
+ caam_prng_alg.registered = true;
+
+ dev_info(ctrldev,
+ "rng crypto API alg registered %s\n", caam_prng_alg.rng.base.cra_driver_name);
+
+ return 0;
+}
diff --git a/drivers/crypto/caam/intern.h b/drivers/crypto/caam/intern.h
index 7d45b21bd55a..c2f51365df1b 100644
--- a/drivers/crypto/caam/intern.h
+++ b/drivers/crypto/caam/intern.h
@@ -185,6 +185,21 @@ static inline void caam_rng_exit(struct device *dev) {}

#endif /* CONFIG_CRYPTO_DEV_FSL_CAAM_RNG_API */

+#ifdef CONFIG_CRYPTO_DEV_FSL_CAAM_PRNG_API
+
+int caam_prng_register(struct device *dev);
+void caam_prng_unregister(void *data);
+
+#else
+
+static inline int caam_prng_register(struct device *dev)
+{
+ return 0;
+}
+
+static inline void caam_prng_unregister(void *data) {}
+#endif /* CONFIG_CRYPTO_DEV_FSL_CAAM_PRNG_API */
+
#ifdef CONFIG_CAAM_QI

int caam_qi_algapi_init(struct device *dev);
diff --git a/drivers/crypto/caam/jr.c b/drivers/crypto/caam/jr.c
index 7f2b1101f567..724fdec18bf9 100644
--- a/drivers/crypto/caam/jr.c
+++ b/drivers/crypto/caam/jr.c
@@ -39,6 +39,7 @@ static void register_algs(struct caam_drv_private_jr *jrpriv,
caam_algapi_hash_init(dev);
caam_pkc_init(dev);
jrpriv->hwrng = !caam_rng_init(dev);
+ caam_prng_register(dev);
caam_qi_algapi_init(dev);

algs_unlock:
@@ -53,7 +54,7 @@ static void unregister_algs(void)
goto algs_unlock;

caam_qi_algapi_exit();
-
+ caam_prng_unregister(NULL);
caam_pkc_exit();
caam_algapi_hash_exit();
caam_algapi_exit();
--
2.25.1


2022-04-30 16:26:33

by Horia Geantă

[permalink] [raw]
Subject: Re: [PATCH v4 1/1] crypto: caam/rng: Add support for PRNG

On 4/29/2022 11:45 AM, Meenakshi Aggarwal wrote:
> From: Meenakshi Aggarwal <[email protected]>
>
> Add support for random number generation using PRNG
> mode of CAAM and expose the interface through crypto API.
>
> According to the RM, the HW implementation of the DRBG follows
> NIST SP 800-90A specification for DRBG_Hash SHA-256 function
>
> Signed-off-by: Meenakshi Aggarwal <[email protected]>

There are a few nitpicks below, if you can address them great,
either way here's my
Reviewed-by: Horia Geantă <[email protected]>

> + * Length of used descriptors, see caam_init_desc()
caam_init_desc() does not exist in this file.

> + */
> +#define CAAM_PRNG_DESC_LEN (CAAM_CMD_SZ + \
> + CAAM_CMD_SZ + \
> + CAAM_CMD_SZ + CAAM_PTR_SZ_MAX)
The reseed descriptor length is now smaller.
Memmory allocated by kmalloc() will probably be the same,
but code would be more readable.
If you want to use the same length for both descriptors,
I suggest renaming the define to CAAM_PRNG_MAX_DESC_LEN.

> +static u32 *caam_init_reseed_desc(u32 *desc)
> +{
> + init_job_desc(desc, 0); /* + 1 cmd_sz */
> + /* Generate random bytes: + 1 cmd_sz */
This is a "reseed" operation, not "generate".

> + append_operation(desc, OP_TYPE_CLASS1_ALG | OP_ALG_ALGSEL_RNG |
> + OP_ALG_AS_FINALIZE);
> +
[...]
> +static int caam_prng_generate(struct crypto_rng *tfm,
> + const u8 *src, unsigned int slen,
> + u8 *dst, unsigned int dlen)
> +{
[...]
> + ret = caam_jr_enqueue(jrdev,
> + caam_init_prng_desc(desc, dst_dma, dlen),
> + caam_prng_done, &ctx);
> +
> + if (ret == -EINPROGRESS) {
> + wait_for_completion(&ctx.done);
> + ret = ctx.err;
> + }
> +
> + dma_unmap_single(jrdev, dst_dma, dlen, DMA_FROM_DEVICE);
> +
> + memcpy(dst, buf, dlen);
memcpy() should be performed only when the HW executed the operation
successfully.

Thanks,
Horia