crypto: caam/rng - Add support for PRNG

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 <meenakshi.aggarwal@nxp.com>
Reviewed-by: Horia Geant <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

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

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

drivers/crypto/caam/caamprng.c

+// 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_MAX_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 desc@: ", 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 desc@: ", 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_MAX_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);
+
+	if (!ret)
+		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_MAX_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;
+}

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);

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();