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@xxxxxxxxxxxxxx>
CC: Theodore Ts'o <tytso@xxxxxxx>
CC: Sandy Harris <sandyinchina@xxxxxxxxx>
Signed-off-by: Stephan Mueller <smueller@xxxxxxxxxx>
---
crypto/drbg.c | 28 ++++++++++++++++++++++++++++
include/crypto/drbg.h | 2 ++
2 files changed, 30 insertions(+)
diff --git a/crypto/drbg.c b/crypto/drbg.c
index 36dfece..4e54973 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -1056,6 +1056,27 @@ 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);
+ int ret;
+
+ do {
+ ret = get_blocking_random_bytes(drbg->seed_buf,
+ drbg->seed_buf_len);
+ } while (ret == -ERESTARTSYS);
+
+ 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 +1146,10 @@ 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 +1256,8 @@ 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 +1514,7 @@ unlock:
*/
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);
diff --git a/include/crypto/drbg.h b/include/crypto/drbg.h
index b052698..46994b2 100644
--- a/include/crypto/drbg.h
+++ b/include/crypto/drbg.h
@@ -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;
--
2.1.0
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