diff options
| -rw-r--r-- | crypto/drbg.c | 81 | ||||
| -rw-r--r-- | include/crypto/drbg.h | 2 |
2 files changed, 56 insertions, 27 deletions
diff --git a/crypto/drbg.c b/crypto/drbg.c index 23d444ed3176..36dfece45e88 100644 --- a/crypto/drbg.c +++ b/crypto/drbg.c @@ -1041,6 +1041,21 @@ static struct drbg_state_ops drbg_hash_ops = { * Functions common for DRBG implementations ******************************************************************/ +static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed, + int reseed) +{ + int ret = drbg->d_ops->update(drbg, seed, reseed); + + if (ret) + return ret; + + drbg->seeded = true; + /* 10.1.1.2 / 10.1.1.3 step 5 */ + drbg->reseed_ctr = 1; + + return ret; +} + /* * Seeding or reseeding of the DRBG * @@ -1056,8 +1071,6 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers, bool reseed) { int ret = 0; - unsigned char *entropy = NULL; - size_t entropylen = 0; struct drbg_string data1; LIST_HEAD(seedlist); @@ -1073,26 +1086,10 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers, drbg->test_data.len); pr_devel("DRBG: using test entropy\n"); } else { - /* - * Gather entropy equal to the security strength of the DRBG. - * With a derivation function, a nonce is required in addition - * to the entropy. A nonce must be at least 1/2 of the security - * strength of the DRBG in size. Thus, entropy * nonce is 3/2 - * of the strength. The consideration of a nonce is only - * applicable during initial seeding. - */ - entropylen = drbg_sec_strength(drbg->core->flags); - if (!entropylen) - return -EFAULT; - if (!reseed) - entropylen = ((entropylen + 1) / 2) * 3; pr_devel("DRBG: (re)seeding with %zu bytes of entropy\n", - entropylen); - entropy = kzalloc(entropylen, GFP_KERNEL); - if (!entropy) - return -ENOMEM; - get_random_bytes(entropy, entropylen); - drbg_string_fill(&data1, entropy, entropylen); + drbg->seed_buf_len); + get_random_bytes(drbg->seed_buf, drbg->seed_buf_len); + drbg_string_fill(&data1, drbg->seed_buf, drbg->seed_buf_len); } list_add_tail(&data1.list, &seedlist); @@ -1111,16 +1108,24 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers, memset(drbg->C, 0, drbg_statelen(drbg)); } - ret = drbg->d_ops->update(drbg, &seedlist, reseed); + ret = __drbg_seed(drbg, &seedlist, reseed); + + /* + * Clear the initial entropy buffer as the async call may not overwrite + * that buffer for quite some time. + */ + memzero_explicit(drbg->seed_buf, drbg->seed_buf_len); if (ret) goto out; - - drbg->seeded = true; - /* 10.1.1.2 / 10.1.1.3 step 5 */ - drbg->reseed_ctr = 1; + /* + * For all subsequent seeding calls, we only need the seed buffer + * equal to the security strength of the DRBG. We undo the calculation + * in drbg_alloc_state. + */ + if (!reseed) + drbg->seed_buf_len = drbg->seed_buf_len / 3 * 2; out: - kzfree(entropy); return ret; } @@ -1143,6 +1148,8 @@ static inline void drbg_dealloc_state(struct drbg_state *drbg) drbg->prev = NULL; drbg->fips_primed = false; #endif + kzfree(drbg->seed_buf); + drbg->seed_buf = NULL; } /* @@ -1204,6 +1211,26 @@ static inline int drbg_alloc_state(struct drbg_state *drbg) if (!drbg->scratchpad) goto err; } + + /* + * Gather entropy equal to the security strength of the DRBG. + * With a derivation function, a nonce is required in addition + * to the entropy. A nonce must be at least 1/2 of the security + * strength of the DRBG in size. Thus, entropy * nonce is 3/2 + * of the strength. The consideration of a nonce is only + * applicable during initial seeding. + */ + drbg->seed_buf_len = drbg_sec_strength(drbg->core->flags); + if (!drbg->seed_buf_len) { + ret = -EFAULT; + goto err; + } + /* ensure we have sufficient buffer space for initial seed */ + drbg->seed_buf_len = ((drbg->seed_buf_len + 1) / 2) * 3; + drbg->seed_buf = kzalloc(drbg->seed_buf_len, GFP_KERNEL); + if (!drbg->seed_buf) + goto err; + return 0; err: diff --git a/include/crypto/drbg.h b/include/crypto/drbg.h index 480d7a0f4dac..b0526981aa85 100644 --- a/include/crypto/drbg.h +++ b/include/crypto/drbg.h @@ -119,6 +119,8 @@ struct drbg_state { bool fips_primed; /* Continuous test primed? */ unsigned char *prev; /* FIPS 140-2 continuous test value */ #endif + u8 *seed_buf; /* buffer holding the seed */ + size_t seed_buf_len; const struct drbg_state_ops *d_ops; const struct drbg_core *core; struct drbg_string test_data; |
