diff options
Diffstat (limited to 'crypto/rand/drbg_lib.c')
| -rw-r--r-- | crypto/rand/drbg_lib.c | 225 |
1 files changed, 157 insertions, 68 deletions
diff --git a/crypto/rand/drbg_lib.c b/crypto/rand/drbg_lib.c index 729b49c943727..a13282181d6d1 100644 --- a/crypto/rand/drbg_lib.c +++ b/crypto/rand/drbg_lib.c @@ -82,6 +82,10 @@ static unsigned int slave_reseed_interval = SLAVE_RESEED_INTERVAL; static time_t master_reseed_time_interval = MASTER_RESEED_TIME_INTERVAL; static time_t slave_reseed_time_interval = SLAVE_RESEED_TIME_INTERVAL; +/* A logical OR of all used DRBG flag bits (currently there is only one) */ +static const unsigned int rand_drbg_used_flags = + RAND_DRBG_FLAG_CTR_NO_DF; + static RAND_DRBG *drbg_setup(RAND_DRBG *parent); static RAND_DRBG *rand_drbg_new(int secure, @@ -105,16 +109,27 @@ int RAND_DRBG_set(RAND_DRBG *drbg, int type, unsigned int flags) flags = rand_drbg_flags; } + /* If set is called multiple times - clear the old one */ + if (drbg->type != 0 && (type != drbg->type || flags != drbg->flags)) { + drbg->meth->uninstantiate(drbg); + rand_pool_free(drbg->adin_pool); + drbg->adin_pool = NULL; + } + drbg->state = DRBG_UNINITIALISED; drbg->flags = flags; drbg->type = type; switch (type) { default: + drbg->type = 0; + drbg->flags = 0; + drbg->meth = NULL; RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_UNSUPPORTED_DRBG_TYPE); return 0; case 0: /* Uninitialized; that's okay. */ + drbg->meth = NULL; return 1; case NID_aes_128_ctr: case NID_aes_192_ctr: @@ -123,8 +138,10 @@ int RAND_DRBG_set(RAND_DRBG *drbg, int type, unsigned int flags) break; } - if (ret == 0) + if (ret == 0) { + drbg->state = DRBG_ERROR; RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_ERROR_INITIALISING_DRBG); + } return ret; } @@ -147,7 +164,7 @@ int RAND_DRBG_set_defaults(int type, unsigned int flags) break; } - if ((flags & ~RAND_DRBG_USED_FLAGS) != 0) { + if ((flags & ~rand_drbg_used_flags) != 0) { RANDerr(RAND_F_RAND_DRBG_SET_DEFAULTS, RAND_R_UNSUPPORTED_DRBG_FLAGS); return 0; } @@ -224,11 +241,8 @@ static RAND_DRBG *rand_drbg_new(int secure, return drbg; -err: - if (drbg->secure) - OPENSSL_secure_free(drbg); - else - OPENSSL_free(drbg); + err: + RAND_DRBG_free(drbg); return NULL; } @@ -253,6 +267,7 @@ void RAND_DRBG_free(RAND_DRBG *drbg) if (drbg->meth != NULL) drbg->meth->uninstantiate(drbg); + rand_pool_free(drbg->adin_pool); CRYPTO_THREAD_lock_free(drbg->lock); CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DRBG, drbg, &drbg->ex_data); @@ -312,11 +327,18 @@ int RAND_DRBG_instantiate(RAND_DRBG *drbg, max_entropylen += drbg->max_noncelen; } + drbg->reseed_next_counter = tsan_load(&drbg->reseed_prop_counter); + if (drbg->reseed_next_counter) { + drbg->reseed_next_counter++; + if(!drbg->reseed_next_counter) + drbg->reseed_next_counter = 1; + } + if (drbg->get_entropy != NULL) entropylen = drbg->get_entropy(drbg, &entropy, min_entropy, min_entropylen, max_entropylen, 0); if (entropylen < min_entropylen - || entropylen > max_entropylen) { + || entropylen > max_entropylen) { RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_ENTROPY); goto end; } @@ -337,29 +359,15 @@ int RAND_DRBG_instantiate(RAND_DRBG *drbg, } drbg->state = DRBG_READY; - drbg->generate_counter = 0; + drbg->reseed_gen_counter = 1; drbg->reseed_time = time(NULL); - if (drbg->reseed_counter > 0) { - if (drbg->parent == NULL) - drbg->reseed_counter++; - else - drbg->reseed_counter = drbg->parent->reseed_counter; - } + tsan_store(&drbg->reseed_prop_counter, drbg->reseed_next_counter); -end: + end: if (entropy != NULL && drbg->cleanup_entropy != NULL) drbg->cleanup_entropy(drbg, entropy, entropylen); - if (nonce != NULL && drbg->cleanup_nonce!= NULL ) + if (nonce != NULL && drbg->cleanup_nonce != NULL) drbg->cleanup_nonce(drbg, nonce, noncelen); - if (drbg->pool != NULL) { - if (drbg->state == DRBG_READY) { - RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, - RAND_R_ERROR_ENTROPY_POOL_WAS_IGNORED); - drbg->state = DRBG_ERROR; - } - rand_pool_free(drbg->pool); - drbg->pool = NULL; - } if (drbg->state == DRBG_READY) return 1; return 0; @@ -375,6 +383,7 @@ end: int RAND_DRBG_uninstantiate(RAND_DRBG *drbg) { if (drbg->meth == NULL) { + drbg->state = DRBG_ERROR; RANDerr(RAND_F_RAND_DRBG_UNINSTANTIATE, RAND_R_NO_DRBG_IMPLEMENTATION_SELECTED); return 0; @@ -419,13 +428,21 @@ int RAND_DRBG_reseed(RAND_DRBG *drbg, } drbg->state = DRBG_ERROR; + + drbg->reseed_next_counter = tsan_load(&drbg->reseed_prop_counter); + if (drbg->reseed_next_counter) { + drbg->reseed_next_counter++; + if(!drbg->reseed_next_counter) + drbg->reseed_next_counter = 1; + } + if (drbg->get_entropy != NULL) entropylen = drbg->get_entropy(drbg, &entropy, drbg->strength, drbg->min_entropylen, drbg->max_entropylen, prediction_resistance); if (entropylen < drbg->min_entropylen - || entropylen > drbg->max_entropylen) { + || entropylen > drbg->max_entropylen) { RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ERROR_RETRIEVING_ENTROPY); goto end; } @@ -434,16 +451,11 @@ int RAND_DRBG_reseed(RAND_DRBG *drbg, goto end; drbg->state = DRBG_READY; - drbg->generate_counter = 0; + drbg->reseed_gen_counter = 1; drbg->reseed_time = time(NULL); - if (drbg->reseed_counter > 0) { - if (drbg->parent == NULL) - drbg->reseed_counter++; - else - drbg->reseed_counter = drbg->parent->reseed_counter; - } + tsan_store(&drbg->reseed_prop_counter, drbg->reseed_next_counter); -end: + end: if (entropy != NULL && drbg->cleanup_entropy != NULL) drbg->cleanup_entropy(drbg, entropy, entropylen); if (drbg->state == DRBG_READY) @@ -475,10 +487,12 @@ int rand_drbg_restart(RAND_DRBG *drbg, const unsigned char *adin = NULL; size_t adinlen = 0; - if (drbg->pool != NULL) { + if (drbg->seed_pool != NULL) { RANDerr(RAND_F_RAND_DRBG_RESTART, ERR_R_INTERNAL_ERROR); - rand_pool_free(drbg->pool); - drbg->pool = NULL; + drbg->state = DRBG_ERROR; + rand_pool_free(drbg->seed_pool); + drbg->seed_pool = NULL; + return 0; } if (buffer != NULL) { @@ -486,24 +500,25 @@ int rand_drbg_restart(RAND_DRBG *drbg, if (drbg->max_entropylen < len) { RANDerr(RAND_F_RAND_DRBG_RESTART, RAND_R_ENTROPY_INPUT_TOO_LONG); + drbg->state = DRBG_ERROR; return 0; } if (entropy > 8 * len) { RANDerr(RAND_F_RAND_DRBG_RESTART, RAND_R_ENTROPY_OUT_OF_RANGE); + drbg->state = DRBG_ERROR; return 0; } /* will be picked up by the rand_drbg_get_entropy() callback */ - drbg->pool = rand_pool_new(entropy, len, len); - if (drbg->pool == NULL) + drbg->seed_pool = rand_pool_attach(buffer, len, entropy); + if (drbg->seed_pool == NULL) return 0; - - rand_pool_add(drbg->pool, buffer, len, entropy); } else { if (drbg->max_adinlen < len) { RANDerr(RAND_F_RAND_DRBG_RESTART, RAND_R_ADDITIONAL_INPUT_TOO_LONG); + drbg->state = DRBG_ERROR; return 0; } adin = buffer; @@ -543,14 +558,8 @@ int rand_drbg_restart(RAND_DRBG *drbg, } } - /* check whether a given entropy pool was cleared properly during reseed */ - if (drbg->pool != NULL) { - drbg->state = DRBG_ERROR; - RANDerr(RAND_F_RAND_DRBG_RESTART, ERR_R_INTERNAL_ERROR); - rand_pool_free(drbg->pool); - drbg->pool = NULL; - return 0; - } + rand_pool_free(drbg->seed_pool); + drbg->seed_pool = NULL; return drbg->state == DRBG_READY; } @@ -600,7 +609,7 @@ int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen, } if (drbg->reseed_interval > 0) { - if (drbg->generate_counter >= drbg->reseed_interval) + if (drbg->reseed_gen_counter >= drbg->reseed_interval) reseed_required = 1; } if (drbg->reseed_time_interval > 0) { @@ -609,8 +618,11 @@ int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen, || now - drbg->reseed_time >= drbg->reseed_time_interval) reseed_required = 1; } - if (drbg->reseed_counter > 0 && drbg->parent != NULL) { - if (drbg->reseed_counter != drbg->parent->reseed_counter) + if (drbg->parent != NULL) { + unsigned int reseed_counter = tsan_load(&drbg->reseed_prop_counter); + if (reseed_counter > 0 + && tsan_load(&drbg->parent->reseed_prop_counter) + != reseed_counter) reseed_required = 1; } @@ -629,7 +641,7 @@ int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen, return 0; } - drbg->generate_counter++; + drbg->reseed_gen_counter++; return 1; } @@ -647,9 +659,18 @@ int RAND_DRBG_bytes(RAND_DRBG *drbg, unsigned char *out, size_t outlen) unsigned char *additional = NULL; size_t additional_len; size_t chunk; - size_t ret; + size_t ret = 0; + + if (drbg->adin_pool == NULL) { + if (drbg->type == 0) + goto err; + drbg->adin_pool = rand_pool_new(0, 0, drbg->max_adinlen); + if (drbg->adin_pool == NULL) + goto err; + } - additional_len = rand_drbg_get_additional_data(&additional, drbg->max_adinlen); + additional_len = rand_drbg_get_additional_data(drbg->adin_pool, + &additional); for ( ; outlen > 0; outlen -= chunk, out += chunk) { chunk = outlen; @@ -661,9 +682,9 @@ int RAND_DRBG_bytes(RAND_DRBG *drbg, unsigned char *out, size_t outlen) } ret = 1; -err: - if (additional_len != 0) - OPENSSL_secure_clear_free(additional, additional_len); + err: + if (additional != NULL) + rand_drbg_cleanup_additional_data(drbg->adin_pool, additional); return ret; } @@ -682,7 +703,8 @@ int RAND_DRBG_set_callbacks(RAND_DRBG *drbg, RAND_DRBG_get_nonce_fn get_nonce, RAND_DRBG_cleanup_nonce_fn cleanup_nonce) { - if (drbg->state != DRBG_UNINITIALISED) + if (drbg->state != DRBG_UNINITIALISED + || drbg->parent != NULL) return 0; drbg->get_entropy = get_entropy; drbg->cleanup_entropy = cleanup_entropy; @@ -859,7 +881,7 @@ static RAND_DRBG *drbg_setup(RAND_DRBG *parent) goto err; /* enable seed propagation */ - drbg->reseed_counter = 1; + tsan_store(&drbg->reseed_prop_counter, 1); /* * Ignore instantiation error to support just-in-time instantiation. @@ -948,11 +970,49 @@ static int drbg_bytes(unsigned char *out, int count) return ret; } +/* + * Calculates the minimum length of a full entropy buffer + * which is necessary to seed (i.e. instantiate) the DRBG + * successfully. + */ +size_t rand_drbg_seedlen(RAND_DRBG *drbg) +{ + /* + * If no os entropy source is available then RAND_seed(buffer, bufsize) + * is expected to succeed if and only if the buffer length satisfies + * the following requirements, which follow from the calculations + * in RAND_DRBG_instantiate(). + */ + size_t min_entropy = drbg->strength; + size_t min_entropylen = drbg->min_entropylen; + + /* + * Extra entropy for the random nonce in the absence of a + * get_nonce callback, see comment in RAND_DRBG_instantiate(). + */ + if (drbg->min_noncelen > 0 && drbg->get_nonce == NULL) { + min_entropy += drbg->strength / 2; + min_entropylen += drbg->min_noncelen; + } + + /* + * Convert entropy requirement from bits to bytes + * (dividing by 8 without rounding upwards, because + * all entropy requirements are divisible by 8). + */ + min_entropy >>= 3; + + /* Return a value that satisfies both requirements */ + return min_entropy > min_entropylen ? min_entropy : min_entropylen; +} + /* Implements the default OpenSSL RAND_add() method */ static int drbg_add(const void *buf, int num, double randomness) { int ret = 0; RAND_DRBG *drbg = RAND_DRBG_get0_master(); + size_t buflen; + size_t seedlen; if (drbg == NULL) return 0; @@ -960,20 +1020,49 @@ static int drbg_add(const void *buf, int num, double randomness) if (num < 0 || randomness < 0.0) return 0; - if (randomness > (double)drbg->max_entropylen) { + rand_drbg_lock(drbg); + seedlen = rand_drbg_seedlen(drbg); + + buflen = (size_t)num; + + if (buflen < seedlen || randomness < (double) seedlen) { +#if defined(OPENSSL_RAND_SEED_NONE) + /* + * If no os entropy source is available, a reseeding will fail + * inevitably. So we use a trick to mix the buffer contents into + * the DRBG state without forcing a reseeding: we generate a + * dummy random byte, using the buffer content as additional data. + * Note: This won't work with RAND_DRBG_FLAG_CTR_NO_DF. + */ + unsigned char dummy[1]; + + ret = RAND_DRBG_generate(drbg, dummy, sizeof(dummy), 0, buf, buflen); + rand_drbg_unlock(drbg); + return ret; +#else + /* + * If an os entropy source is avaible then we declare the buffer content + * as additional data by setting randomness to zero and trigger a regular + * reseeding. + */ + randomness = 0.0; +#endif + } + + + if (randomness > (double)seedlen) { /* * The purpose of this check is to bound |randomness| by a * relatively small value in order to prevent an integer * overflow when multiplying by 8 in the rand_drbg_restart() - * call below. + * call below. Note that randomness is measured in bytes, + * not bits, so this value corresponds to eight times the + * security strength. */ - return 0; + randomness = (double)seedlen; } - rand_drbg_lock(drbg); - ret = rand_drbg_restart(drbg, buf, - (size_t)(unsigned int)num, - (size_t)(8*randomness)); + ret = rand_drbg_restart(drbg, buf, buflen, (size_t)(8 * randomness)); rand_drbg_unlock(drbg); return ret; |