From 4c7879907eddd5b3ec09489bc980aab4f44e38dd Mon Sep 17 00:00:00 2001 From: Stephan Mueller Date: Mon, 25 May 2015 15:09:36 +0200 Subject: 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 CC: Theodore Ts'o CC: Sandy Harris Signed-off-by: Stephan Mueller Signed-off-by: Herbert Xu --- crypto/drbg.c | 24 ++++++++++++++++++++++++ include/crypto/drbg.h | 2 ++ 2 files changed, 26 insertions(+) diff --git a/crypto/drbg.c b/crypto/drbg.c index 36dfece45e88..aca86847ea49 100644 --- a/crypto/drbg.c +++ b/crypto/drbg.c @@ -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 @@ 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 b0526981aa85..46994b25dc85 100644 --- a/include/crypto/drbg.h +++ b/include/crypto/drbg.h @@ -51,6 +51,7 @@ #include #include #include +#include /* * 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; -- cgit v1.2.3