Commit ea53756d authored by Andrey Smirnov's avatar Andrey Smirnov Committed by Herbert Xu
Browse files

crypto: caam - limit single JD RNG output to maximum of 16 bytes 

In order to follow recommendation in SP800-90C (section "9.4 The
Oversampling-NRBG Construction") limit the output of "generate" JD
submitted to CAAM. See
https://lore.kernel.org/linux-crypto/VI1PR0402MB3485EF10976A4A69F90E5B0F98580@VI1PR0402MB3485.eurprd04.prod.outlook.com/


for more details.

This change should make CAAM's hwrng driver good enough to have 1024
quality rating.

Signed-off-by: default avatarAndrey Smirnov <andrew.smirnov@gmail.com>
Reviewed-by: default avatarHoria Geantă <horia.geanta@nxp.com>
Cc: Chris Healy <cphealy@gmail.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Horia Geantă <horia.geanta@nxp.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Iuliana Prodan <iuliana.prodan@nxp.com>
Cc: linux-crypto@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-imx@nxp.com
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 358ba762

drivers/crypto/caam/caamrng.c

+11 −10
Original line number Diff line number Diff line
@@ -22,9 +22,7 @@ 
#include "jr.h"

#include "error.h"



#define CAAM_RNG_MAX_FIFO_STORE_SIZE	U16_MAX



#define CAAM_RNG_FIFO_LEN		SZ_32K /* Must be a multiple of 2 */

#define CAAM_RNG_MAX_FIFO_STORE_SIZE	16



/*

 * Length of used descriptors, see caam_init_desc()
@@ -65,14 +63,15 @@ static void caam_rng_done(struct device *jrdev, u32 *desc, u32 err, 
	complete(jctx->done);

}



static u32 *caam_init_desc(u32 *desc, dma_addr_t dst_dma, int len)

static u32 *caam_init_desc(u32 *desc, dma_addr_t dst_dma)

{

	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 |

			 OP_ALG_PR_ON);

	/* Store bytes: + 1 cmd_sz + caam_ptr_sz  */

	append_fifo_store(desc, dst_dma, len, FIFOST_TYPE_RNGSTORE);

	append_fifo_store(desc, dst_dma,

			  CAAM_RNG_MAX_FIFO_STORE_SIZE, FIFOST_TYPE_RNGSTORE);



	print_hex_dump_debug("rng job desc@: ", DUMP_PREFIX_ADDRESS,

			     16, 4, desc, desc_bytes(desc), 1);
@@ -92,7 +91,7 @@ static int caam_rng_read_one(struct device *jrdev, 
		.err  = &ret,

	};



	len = min_t(int, len, CAAM_RNG_MAX_FIFO_STORE_SIZE);

	len = CAAM_RNG_MAX_FIFO_STORE_SIZE;



	dst_dma = dma_map_single(jrdev, dst, len, DMA_FROM_DEVICE);

	if (dma_mapping_error(jrdev, dst_dma)) {
@@ -102,7 +101,7 @@ static int caam_rng_read_one(struct device *jrdev, 


	init_completion(done);

	err = caam_jr_enqueue(jrdev,

			      caam_init_desc(desc, dst_dma, len),

			      caam_init_desc(desc, dst_dma),

			      caam_rng_done, &jctx);

	if (err == -EINPROGRESS) {

		wait_for_completion(done);
@@ -122,7 +121,7 @@ static void caam_rng_fill_async(struct caam_rng_ctx *ctx) 


	sg_init_table(sg, ARRAY_SIZE(sg));

	nents = kfifo_dma_in_prepare(&ctx->fifo, sg, ARRAY_SIZE(sg),

				     CAAM_RNG_FIFO_LEN);

				     CAAM_RNG_MAX_FIFO_STORE_SIZE);

	if (!nents)

		return;
@@ -156,7 +155,7 @@ static int caam_read(struct hwrng *rng, void *dst, size_t max, bool wait) 
	}



	out = kfifo_out(&ctx->fifo, dst, max);

	if (kfifo_len(&ctx->fifo) <= CAAM_RNG_FIFO_LEN / 2)

	if (kfifo_is_empty(&ctx->fifo))

		schedule_work(&ctx->worker);



	return out;
@@ -186,7 +185,8 @@ static int caam_init(struct hwrng *rng) 
	if (!ctx->desc_async)

		return -ENOMEM;



	if (kfifo_alloc(&ctx->fifo, CAAM_RNG_FIFO_LEN, GFP_DMA | GFP_KERNEL))

	if (kfifo_alloc(&ctx->fifo, CAAM_RNG_MAX_FIFO_STORE_SIZE,

			GFP_DMA | GFP_KERNEL))

		return -ENOMEM;



	INIT_WORK(&ctx->worker, caam_rng_worker);
@@ -246,6 +246,7 @@ int caam_rng_init(struct device *ctrldev) 
	ctx->rng.cleanup = caam_cleanup;

	ctx->rng.read    = caam_read;

	ctx->rng.priv    = (unsigned long)ctx;

	ctx->rng.quality = 1024;



	dev_info(ctrldev, "registering rng-caam\n");

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