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Commit 4c787990 authored by Stephan Mueller's avatar Stephan Mueller Committed by Herbert Xu
Browse files

crypto: drbg - add async seeding operation 



The async seeding operation is triggered during initalization right
after the first non-blocking seeding is completed. As required by the
asynchronous operation of random.c, a callback function is provided that
is triggered by random.c once entropy is available. That callback
function performs the actual seeding of the DRBG.

CC: Andreas Steffen <andreas.steffen@strongswan.org>
CC: Theodore Ts'o <tytso@mit.edu>
CC: Sandy Harris <sandyinchina@gmail.com>
Signed-off-by: default avatarStephan Mueller <smueller@chronox.de>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 3d6a5f75

crypto/drbg.c

+24 −0
Original line number Diff line number Diff line
@@ -1056,6 +1056,23 @@ static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed, 
	return ret;

}



static void drbg_async_seed(struct work_struct *work)

{

	struct drbg_string data;

	LIST_HEAD(seedlist);

	struct drbg_state *drbg = container_of(work, struct drbg_state,

					       seed_work);



	get_blocking_random_bytes(drbg->seed_buf, drbg->seed_buf_len);



	drbg_string_fill(&data, drbg->seed_buf, drbg->seed_buf_len);

	list_add_tail(&data.list, &seedlist);

	mutex_lock(&drbg->drbg_mutex);

	__drbg_seed(drbg, &seedlist, true);

	memzero_explicit(drbg->seed_buf, drbg->seed_buf_len);

	mutex_unlock(&drbg->drbg_mutex);

}



/*

 * Seeding or reseeding of the DRBG

 *
@@ -1125,6 +1142,10 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers, 
	if (!reseed)

		drbg->seed_buf_len = drbg->seed_buf_len / 3 * 2;



	/* Invoke asynchronous seeding unless DRBG is in test mode. */

	if (!list_empty(&drbg->test_data.list) && !reseed)

		schedule_work(&drbg->seed_work);



out:

	return ret;

}
@@ -1231,6 +1252,8 @@ static inline int drbg_alloc_state(struct drbg_state *drbg) 
	if (!drbg->seed_buf)

		goto err;



	INIT_WORK(&drbg->seed_work, drbg_async_seed);



	return 0;



err:
@@ -1487,6 +1510,7 @@ static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers, 
 */

static int drbg_uninstantiate(struct drbg_state *drbg)

{

	cancel_work_sync(&drbg->seed_work);

	if (drbg->d_ops)

		drbg->d_ops->crypto_fini(drbg);

	drbg_dealloc_state(drbg);

include/crypto/drbg.h

+2 −0
Original line number Diff line number Diff line
@@ -51,6 +51,7 @@ 
#include <linux/fips.h>

#include <linux/mutex.h>

#include <linux/list.h>

#include <linux/workqueue.h>



/*

 * Concatenation Helper and string operation helper
@@ -119,6 +120,7 @@ struct drbg_state { 
	bool fips_primed;	/* Continuous test primed? */

	unsigned char *prev;	/* FIPS 140-2 continuous test value */

#endif

	struct work_struct seed_work;	/* asynchronous seeding support */

	u8 *seed_buf;			/* buffer holding the seed */

	size_t seed_buf_len;

	const struct drbg_state_ops *d_ops;