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: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/drbg.c b/crypto/drbg.c
index 36dfece..aca8684 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -1056,6 +1056,23 @@
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 @@
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 @@
if (!drbg->seed_buf)
goto err;
+ INIT_WORK(&drbg->seed_work, drbg_async_seed);
+
return 0;
err:
@@ -1487,6 +1510,7 @@
*/
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);