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openssl/crypto/rand/drbg_lib.c

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/*
* Copyright 2011-2022 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <string.h>
#include <openssl/crypto.h>
#include <openssl/err.h>
#include <openssl/rand.h>
#include "rand_local.h"
#include "internal/thread_once.h"
#include "crypto/rand.h"
#include "crypto/cryptlib.h"
/*
* Support framework for NIST SP 800-90A DRBG
*
* See manual page RAND_DRBG(7) for a general overview.
*
* The OpenSSL model is to have new and free functions, and that new
* does all initialization. That is not the NIST model, which has
* instantiation and un-instantiate, and re-use within a new/free
* lifecycle. (No doubt this comes from the desire to support hardware
* DRBG, where allocation of resources on something like an HSM is
* a much bigger deal than just re-setting an allocated resource.)
*/
/*
* The three shared DRBG instances
*
* There are three shared DRBG instances: <master>, <public>, and <private>.
*/
/*
* The <master> DRBG
*
* Not used directly by the application, only for reseeding the two other
* DRBGs. It reseeds itself by pulling either randomness from os entropy
* sources or by consuming randomness which was added by RAND_add().
*
* The <master> DRBG is a global instance which is accessed concurrently by
* all threads. The necessary locking is managed automatically by its child
* DRBG instances during reseeding.
*/
static RAND_DRBG *master_drbg;
/*
* The <public> DRBG
*
* Used by default for generating random bytes using RAND_bytes().
*
* The <public> DRBG is thread-local, i.e., there is one instance per thread.
*/
static CRYPTO_THREAD_LOCAL public_drbg;
/*
* The <private> DRBG
*
* Used by default for generating private keys using RAND_priv_bytes()
*
* The <private> DRBG is thread-local, i.e., there is one instance per thread.
*/
static CRYPTO_THREAD_LOCAL private_drbg;
/* NIST SP 800-90A DRBG recommends the use of a personalization string. */
static const char ossl_pers_string[] = "OpenSSL NIST SP 800-90A DRBG";
static CRYPTO_ONCE rand_drbg_init = CRYPTO_ONCE_STATIC_INIT;
static int rand_drbg_type = RAND_DRBG_TYPE;
static unsigned int rand_drbg_flags = RAND_DRBG_FLAGS;
static unsigned int master_reseed_interval = MASTER_RESEED_INTERVAL;
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,
int type,
unsigned int flags,
RAND_DRBG *parent);
/*
* Set/initialize |drbg| to be of type |type|, with optional |flags|.
*
* If |type| and |flags| are zero, use the defaults
*
* Returns 1 on success, 0 on failure.
*/
int RAND_DRBG_set(RAND_DRBG *drbg, int type, unsigned int flags)
{
int ret = 1;
if (type == 0 && flags == 0) {
type = rand_drbg_type;
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:
case NID_aes_256_ctr:
ret = drbg_ctr_init(drbg);
break;
}
if (ret == 0) {
drbg->state = DRBG_ERROR;
RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_ERROR_INITIALISING_DRBG);
}
return ret;
}
/*
* Set/initialize default |type| and |flag| for new drbg instances.
*
* Returns 1 on success, 0 on failure.
*/
int RAND_DRBG_set_defaults(int type, unsigned int flags)
{
int ret = 1;
switch (type) {
default:
RANDerr(RAND_F_RAND_DRBG_SET_DEFAULTS, RAND_R_UNSUPPORTED_DRBG_TYPE);
return 0;
case NID_aes_128_ctr:
case NID_aes_192_ctr:
case NID_aes_256_ctr:
break;
}
if ((flags & ~rand_drbg_used_flags) != 0) {
RANDerr(RAND_F_RAND_DRBG_SET_DEFAULTS, RAND_R_UNSUPPORTED_DRBG_FLAGS);
return 0;
}
rand_drbg_type = type;
rand_drbg_flags = flags;
return ret;
}
/*
* Allocate memory and initialize a new DRBG. The DRBG is allocated on
* the secure heap if |secure| is nonzero and the secure heap is enabled.
* The |parent|, if not NULL, will be used as random source for reseeding.
*
* Returns a pointer to the new DRBG instance on success, NULL on failure.
*/
static RAND_DRBG *rand_drbg_new(int secure,
int type,
unsigned int flags,
RAND_DRBG *parent)
{
RAND_DRBG *drbg = secure ? OPENSSL_secure_zalloc(sizeof(*drbg))
: OPENSSL_zalloc(sizeof(*drbg));
if (drbg == NULL) {
RANDerr(RAND_F_RAND_DRBG_NEW, ERR_R_MALLOC_FAILURE);
return NULL;
}
drbg->secure = secure && CRYPTO_secure_allocated(drbg);
drbg->fork_id = openssl_get_fork_id();
drbg->parent = parent;
if (parent == NULL) {
drbg->get_entropy = rand_drbg_get_entropy;
drbg->cleanup_entropy = rand_drbg_cleanup_entropy;
#ifndef RAND_DRBG_GET_RANDOM_NONCE
drbg->get_nonce = rand_drbg_get_nonce;
drbg->cleanup_nonce = rand_drbg_cleanup_nonce;
#endif
drbg->reseed_interval = master_reseed_interval;
drbg->reseed_time_interval = master_reseed_time_interval;
} else {
drbg->get_entropy = rand_drbg_get_entropy;
drbg->cleanup_entropy = rand_drbg_cleanup_entropy;
/*
* Do not provide nonce callbacks, the child DRBGs will
* obtain their nonce using random bits from the parent.
*/
drbg->reseed_interval = slave_reseed_interval;
drbg->reseed_time_interval = slave_reseed_time_interval;
}
if (RAND_DRBG_set(drbg, type, flags) == 0)
goto err;
if (parent != NULL) {
rand_drbg_lock(parent);
if (drbg->strength > parent->strength) {
/*
* We currently don't support the algorithm from NIST SP 800-90C
* 10.1.2 to use a weaker DRBG as source
*/
rand_drbg_unlock(parent);
RANDerr(RAND_F_RAND_DRBG_NEW, RAND_R_PARENT_STRENGTH_TOO_WEAK);
goto err;
}
rand_drbg_unlock(parent);
}
return drbg;
err:
RAND_DRBG_free(drbg);
return NULL;
}
RAND_DRBG *RAND_DRBG_new(int type, unsigned int flags, RAND_DRBG *parent)
{
return rand_drbg_new(0, type, flags, parent);
}
RAND_DRBG *RAND_DRBG_secure_new(int type, unsigned int flags, RAND_DRBG *parent)
{
return rand_drbg_new(1, type, flags, parent);
}
/*
* Uninstantiate |drbg| and free all memory.
*/
void RAND_DRBG_free(RAND_DRBG *drbg)
{
if (drbg == NULL)
return;
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);
if (drbg->secure)
OPENSSL_secure_clear_free(drbg, sizeof(*drbg));
else
OPENSSL_clear_free(drbg, sizeof(*drbg));
}
/*
* Instantiate |drbg|, after it has been initialized. Use |pers| and
* |perslen| as prediction-resistance input.
*
* Requires that drbg->lock is already locked for write, if non-null.
*
* Returns 1 on success, 0 on failure.
*/
int RAND_DRBG_instantiate(RAND_DRBG *drbg,
const unsigned char *pers, size_t perslen)
{
unsigned char *nonce = NULL, *entropy = NULL;
size_t noncelen = 0, entropylen = 0;
size_t min_entropy = drbg->strength;
size_t min_entropylen = drbg->min_entropylen;
size_t max_entropylen = drbg->max_entropylen;
if (perslen > drbg->max_perslen) {
RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
RAND_R_PERSONALISATION_STRING_TOO_LONG);
goto end;
}
if (drbg->meth == NULL) {
RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
RAND_R_NO_DRBG_IMPLEMENTATION_SELECTED);
goto end;
}
if (drbg->state != DRBG_UNINITIALISED) {
RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
drbg->state == DRBG_ERROR ? RAND_R_IN_ERROR_STATE
: RAND_R_ALREADY_INSTANTIATED);
goto end;
}
drbg->state = DRBG_ERROR;
/*
* NIST SP800-90Ar1 section 9.1 says you can combine getting the entropy
* and nonce in 1 call by increasing the entropy with 50% and increasing
* the minimum length to accommodate the length of the nonce.
* We do this in case a nonce is require and get_nonce is NULL.
*/
if (drbg->min_noncelen > 0 && drbg->get_nonce == NULL) {
min_entropy += drbg->strength / 2;
min_entropylen += drbg->min_noncelen;
max_entropylen += drbg->max_noncelen;
}
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) {
RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_ENTROPY);
goto end;
}
if (drbg->min_noncelen > 0 && drbg->get_nonce != NULL) {
noncelen = drbg->get_nonce(drbg, &nonce, drbg->strength / 2,
drbg->min_noncelen, drbg->max_noncelen);
if (noncelen < drbg->min_noncelen || noncelen > drbg->max_noncelen) {
RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_NONCE);
goto end;
}
}
if (!drbg->meth->instantiate(drbg, entropy, entropylen,
nonce, noncelen, pers, perslen)) {
RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_INSTANTIATING_DRBG);
goto end;
}
drbg->state = DRBG_READY;
drbg->generate_counter = 1;
drbg->reseed_time = time(NULL);
if (drbg->enable_reseed_propagation && drbg->parent == NULL)
tsan_counter(&drbg->reseed_counter);
end:
if (entropy != NULL && drbg->cleanup_entropy != NULL)
drbg->cleanup_entropy(drbg, entropy, entropylen);
if (nonce != NULL && drbg->cleanup_nonce != NULL)
drbg->cleanup_nonce(drbg, nonce, noncelen);
if (drbg->state == DRBG_READY)
return 1;
return 0;
}
/*
* Uninstantiate |drbg|. Must be instantiated before it can be used.
*
* Requires that drbg->lock is already locked for write, if non-null.
*
* Returns 1 on success, 0 on failure.
*/
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;
}
/* Clear the entire drbg->ctr struct, then reset some important
* members of the drbg->ctr struct (e.g. keysize, df_ks) to their
* initial values.
*/
drbg->meth->uninstantiate(drbg);
return RAND_DRBG_set(drbg, drbg->type, drbg->flags);
}
/*
* Reseed |drbg|, mixing in the specified data
*
* Requires that drbg->lock is already locked for write, if non-null.
*
* Returns 1 on success, 0 on failure.
*/
int RAND_DRBG_reseed(RAND_DRBG *drbg,
const unsigned char *adin, size_t adinlen,
int prediction_resistance)
{
unsigned char *entropy = NULL;
size_t entropylen = 0;
if (drbg->state == DRBG_ERROR) {
RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_IN_ERROR_STATE);
return 0;
}
if (drbg->state == DRBG_UNINITIALISED) {
RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_NOT_INSTANTIATED);
return 0;
}
if (adin == NULL) {
adinlen = 0;
} else if (adinlen > drbg->max_adinlen) {
RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
return 0;
}
drbg->state = DRBG_ERROR;
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) {
RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ERROR_RETRIEVING_ENTROPY);
goto end;
}
if (!drbg->meth->reseed(drbg, entropy, entropylen, adin, adinlen))
goto end;
drbg->state = DRBG_READY;
drbg->generate_counter = 1;
drbg->reseed_time = time(NULL);
if (drbg->enable_reseed_propagation && drbg->parent == NULL)
tsan_counter(&drbg->reseed_counter);
end:
if (entropy != NULL && drbg->cleanup_entropy != NULL)
drbg->cleanup_entropy(drbg, entropy, entropylen);
if (drbg->state == DRBG_READY)
return 1;
return 0;
}
/*
* Restart |drbg|, using the specified entropy or additional input
*
* Tries its best to get the drbg instantiated by all means,
* regardless of its current state.
*
* Optionally, a |buffer| of |len| random bytes can be passed,
* which is assumed to contain at least |entropy| bits of entropy.
*
* If |entropy| > 0, the buffer content is used as entropy input.
*
* If |entropy| == 0, the buffer content is used as additional input
*
* Returns 1 on success, 0 on failure.
*
* This function is used internally only.
*/
int rand_drbg_restart(RAND_DRBG *drbg,
const unsigned char *buffer, size_t len, size_t entropy)
{
int reseeded = 0;
const unsigned char *adin = NULL;
size_t adinlen = 0;
if (drbg->seed_pool != NULL) {
RANDerr(RAND_F_RAND_DRBG_RESTART, ERR_R_INTERNAL_ERROR);
drbg->state = DRBG_ERROR;
rand_pool_free(drbg->seed_pool);
drbg->seed_pool = NULL;
return 0;
}
if (buffer != NULL) {
if (entropy > 0) {
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->seed_pool = rand_pool_attach(buffer, len, entropy);
if (drbg->seed_pool == NULL)
return 0;
} 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;
adinlen = len;
}
}
/* repair error state */
if (drbg->state == DRBG_ERROR)
RAND_DRBG_uninstantiate(drbg);
/* repair uninitialized state */
if (drbg->state == DRBG_UNINITIALISED) {
/* reinstantiate drbg */
RAND_DRBG_instantiate(drbg,
(const unsigned char *) ossl_pers_string,
sizeof(ossl_pers_string) - 1);
/* already reseeded. prevent second reseeding below */
reseeded = (drbg->state == DRBG_READY);
}
/* refresh current state if entropy or additional input has been provided */
if (drbg->state == DRBG_READY) {
if (adin != NULL) {
/*
* mix in additional input without reseeding
*
* Similar to RAND_DRBG_reseed(), but the provided additional
* data |adin| is mixed into the current state without pulling
* entropy from the trusted entropy source using get_entropy().
* This is not a reseeding in the strict sense of NIST SP 800-90A.
*/
drbg->meth->reseed(drbg, adin, adinlen, NULL, 0);
} else if (reseeded == 0) {
/* do a full reseeding if it has not been done yet above */
if (!RAND_DRBG_reseed(drbg, NULL, 0, 0)) {
RANDerr(RAND_F_RAND_DRBG_RESTART, RAND_R_RESEED_ERROR);
}
}
}
rand_pool_free(drbg->seed_pool);
drbg->seed_pool = NULL;
return drbg->state == DRBG_READY;
}
/*
* Generate |outlen| bytes into the buffer at |out|. Reseed if we need
* to or if |prediction_resistance| is set. Additional input can be
* sent in |adin| and |adinlen|.
*
* Requires that drbg->lock is already locked for write, if non-null.
*
* Returns 1 on success, 0 on failure.
*
*/
int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen,
int prediction_resistance,
const unsigned char *adin, size_t adinlen)
{
int fork_id;
int reseed_required = 0;
if (drbg->state != DRBG_READY) {
/* try to recover from previous errors */
rand_drbg_restart(drbg, NULL, 0, 0);
if (drbg->state == DRBG_ERROR) {
RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_IN_ERROR_STATE);
return 0;
}
if (drbg->state == DRBG_UNINITIALISED) {
RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_NOT_INSTANTIATED);
return 0;
}
}
if (outlen > drbg->max_request) {
RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_REQUEST_TOO_LARGE_FOR_DRBG);
return 0;
}
if (adinlen > drbg->max_adinlen) {
RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
return 0;
}
fork_id = openssl_get_fork_id();
if (drbg->fork_id != fork_id) {
drbg->fork_id = fork_id;
reseed_required = 1;
}
if (drbg->reseed_interval > 0) {
if (drbg->generate_counter >= drbg->reseed_interval)
reseed_required = 1;
}
if (drbg->reseed_time_interval > 0) {
time_t now = time(NULL);
if (now < drbg->reseed_time
|| now - drbg->reseed_time >= drbg->reseed_time_interval)
reseed_required = 1;
}
if (drbg->enable_reseed_propagation && drbg->parent != NULL) {
if (drbg->reseed_counter != tsan_load(&drbg->parent->reseed_counter))
reseed_required = 1;
}
if (reseed_required || prediction_resistance) {
if (!RAND_DRBG_reseed(drbg, adin, adinlen, prediction_resistance)) {
RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_RESEED_ERROR);
return 0;
}
adin = NULL;
adinlen = 0;
}
if (!drbg->meth->generate(drbg, out, outlen, adin, adinlen)) {
drbg->state = DRBG_ERROR;
RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_GENERATE_ERROR);
return 0;
}
drbg->generate_counter++;
return 1;
}
/*
* Generates |outlen| random bytes and stores them in |out|. It will
* using the given |drbg| to generate the bytes.
*
* Requires that drbg->lock is already locked for write, if non-null.
*
* Returns 1 on success 0 on failure.
*/
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 = 0;
if (drbg->adin_pool == NULL) {
if (drbg->type == 0)
goto err;
drbg->adin_pool = rand_pool_new(0, 0, 0, drbg->max_adinlen);
if (drbg->adin_pool == NULL)
goto err;
}
additional_len = rand_drbg_get_additional_data(drbg->adin_pool,
&additional);
for ( ; outlen > 0; outlen -= chunk, out += chunk) {
chunk = outlen;
if (chunk > drbg->max_request)
chunk = drbg->max_request;
ret = RAND_DRBG_generate(drbg, out, chunk, 0, additional, additional_len);
if (!ret)
goto err;
}
ret = 1;
err:
if (additional != NULL)
rand_drbg_cleanup_additional_data(drbg->adin_pool, additional);
return ret;
}
/*
* Set the RAND_DRBG callbacks for obtaining entropy and nonce.
*
* Setting the callbacks is allowed only if the drbg has not been
* initialized yet. Otherwise, the operation will fail.
*
* Returns 1 on success, 0 on failure.
*/
int RAND_DRBG_set_callbacks(RAND_DRBG *drbg,
RAND_DRBG_get_entropy_fn get_entropy,
RAND_DRBG_cleanup_entropy_fn cleanup_entropy,
RAND_DRBG_get_nonce_fn get_nonce,
RAND_DRBG_cleanup_nonce_fn cleanup_nonce)
{
if (drbg->state != DRBG_UNINITIALISED)
return 0;
drbg->get_entropy = get_entropy;
drbg->cleanup_entropy = cleanup_entropy;
drbg->get_nonce = get_nonce;
drbg->cleanup_nonce = cleanup_nonce;
return 1;
}
/*
* Set the reseed interval.
*
* The drbg will reseed automatically whenever the number of generate
* requests exceeds the given reseed interval. If the reseed interval
* is 0, then this feature is disabled.
*
* Returns 1 on success, 0 on failure.
*/
int RAND_DRBG_set_reseed_interval(RAND_DRBG *drbg, unsigned int interval)
{
if (interval > MAX_RESEED_INTERVAL)
return 0;
drbg->reseed_interval = interval;
return 1;
}
/*
* Set the reseed time interval.
*
* The drbg will reseed automatically whenever the time elapsed since
* the last reseeding exceeds the given reseed time interval. For safety,
* a reseeding will also occur if the clock has been reset to a smaller
* value.
*
* Returns 1 on success, 0 on failure.
*/
int RAND_DRBG_set_reseed_time_interval(RAND_DRBG *drbg, time_t interval)
{
if (interval > MAX_RESEED_TIME_INTERVAL)
return 0;
drbg->reseed_time_interval = interval;
return 1;
}
/*
* Set the default values for reseed (time) intervals of new DRBG instances
*
* The default values can be set independently for master DRBG instances
* (without a parent) and slave DRBG instances (with parent).
*
* Returns 1 on success, 0 on failure.
*/
int RAND_DRBG_set_reseed_defaults(
unsigned int _master_reseed_interval,
unsigned int _slave_reseed_interval,
time_t _master_reseed_time_interval,
time_t _slave_reseed_time_interval
)
{
if (_master_reseed_interval > MAX_RESEED_INTERVAL
|| _slave_reseed_interval > MAX_RESEED_INTERVAL)
return 0;
if (_master_reseed_time_interval > MAX_RESEED_TIME_INTERVAL
|| _slave_reseed_time_interval > MAX_RESEED_TIME_INTERVAL)
return 0;
master_reseed_interval = _master_reseed_interval;
slave_reseed_interval = _slave_reseed_interval;
master_reseed_time_interval = _master_reseed_time_interval;
slave_reseed_time_interval = _slave_reseed_time_interval;
return 1;
}
/*
* Locks the given drbg. Locking a drbg which does not have locking
* enabled is considered a successful no-op.
*
* Returns 1 on success, 0 on failure.
*/
int rand_drbg_lock(RAND_DRBG *drbg)
{
if (drbg->lock != NULL)
return CRYPTO_THREAD_write_lock(drbg->lock);
return 1;
}
/*
* Unlocks the given drbg. Unlocking a drbg which does not have locking
* enabled is considered a successful no-op.
*
* Returns 1 on success, 0 on failure.
*/
int rand_drbg_unlock(RAND_DRBG *drbg)
{
if (drbg->lock != NULL)
return CRYPTO_THREAD_unlock(drbg->lock);
return 1;
}
/*
* Enables locking for the given drbg
*
* Locking can only be enabled if the random generator
* is in the uninitialized state.
*
* Returns 1 on success, 0 on failure.
*/
int rand_drbg_enable_locking(RAND_DRBG *drbg)
{
if (drbg->state != DRBG_UNINITIALISED) {
RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
RAND_R_DRBG_ALREADY_INITIALIZED);
return 0;
}
if (drbg->lock == NULL) {
if (drbg->parent != NULL && drbg->parent->lock == NULL) {
RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
RAND_R_PARENT_LOCKING_NOT_ENABLED);
return 0;
}
drbg->lock = CRYPTO_THREAD_lock_new();
if (drbg->lock == NULL) {
RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
RAND_R_FAILED_TO_CREATE_LOCK);
return 0;
}
}
return 1;
}
/*
* Get and set the EXDATA
*/
int RAND_DRBG_set_ex_data(RAND_DRBG *drbg, int idx, void *arg)
{
return CRYPTO_set_ex_data(&drbg->ex_data, idx, arg);
}
void *RAND_DRBG_get_ex_data(const RAND_DRBG *drbg, int idx)
{
return CRYPTO_get_ex_data(&drbg->ex_data, idx);
}
/*
* The following functions provide a RAND_METHOD that works on the
* global DRBG. They lock.
*/
/*
* Allocates a new global DRBG on the secure heap (if enabled) and
* initializes it with default settings.
*
* Returns a pointer to the new DRBG instance on success, NULL on failure.
*/
static RAND_DRBG *drbg_setup(RAND_DRBG *parent)
{
RAND_DRBG *drbg;
drbg = RAND_DRBG_secure_new(rand_drbg_type, rand_drbg_flags, parent);
if (drbg == NULL)
return NULL;
/* Only the master DRBG needs to have a lock */
if (parent == NULL && rand_drbg_enable_locking(drbg) == 0)
goto err;
/* enable reseed propagation */
drbg->enable_reseed_propagation = 1;
drbg->reseed_counter = 1;
/*
* Ignore instantiation error to support just-in-time instantiation.
*
* The state of the drbg will be checked in RAND_DRBG_generate() and
* an automatic recovery is attempted.
*/
(void)RAND_DRBG_instantiate(drbg,
(const unsigned char *) ossl_pers_string,
sizeof(ossl_pers_string) - 1);
return drbg;
err:
RAND_DRBG_free(drbg);
return NULL;
}
/*
* Initialize the global DRBGs on first use.
* Returns 1 on success, 0 on failure.
*/
DEFINE_RUN_ONCE_STATIC(do_rand_drbg_init)
{
/*
* ensure that libcrypto is initialized, otherwise the
* DRBG locks are not cleaned up properly
*/
if (!OPENSSL_init_crypto(0, NULL))
return 0;
if (!CRYPTO_THREAD_init_local(&private_drbg, NULL))
return 0;
if (!CRYPTO_THREAD_init_local(&public_drbg, NULL))
goto err1;
master_drbg = drbg_setup(NULL);
if (master_drbg == NULL)
goto err2;
return 1;
err2:
CRYPTO_THREAD_cleanup_local(&public_drbg);
err1:
CRYPTO_THREAD_cleanup_local(&private_drbg);
return 0;
}
/* Clean up the global DRBGs before exit */
void rand_drbg_cleanup_int(void)
{
if (master_drbg != NULL) {
RAND_DRBG_free(master_drbg);
master_drbg = NULL;
CRYPTO_THREAD_cleanup_local(&private_drbg);
CRYPTO_THREAD_cleanup_local(&public_drbg);
}
}
void drbg_delete_thread_state(void)
{
RAND_DRBG *drbg;
drbg = CRYPTO_THREAD_get_local(&public_drbg);
CRYPTO_THREAD_set_local(&public_drbg, NULL);
RAND_DRBG_free(drbg);
drbg = CRYPTO_THREAD_get_local(&private_drbg);
CRYPTO_THREAD_set_local(&private_drbg, NULL);
RAND_DRBG_free(drbg);
}
/* Implements the default OpenSSL RAND_bytes() method */
static int drbg_bytes(unsigned char *out, int count)
{
int ret;
RAND_DRBG *drbg = RAND_DRBG_get0_public();
if (drbg == NULL)
return 0;
ret = RAND_DRBG_bytes(drbg, out, 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;
if (num < 0 || randomness < 0.0)
return 0;
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 available 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. Note that randomness is measured in bytes,
* not bits, so this value corresponds to eight times the
* security strength.
*/
randomness = (double)seedlen;
}
ret = rand_drbg_restart(drbg, buf, buflen, (size_t)(8 * randomness));
rand_drbg_unlock(drbg);
return ret;
}
/* Implements the default OpenSSL RAND_seed() method */
static int drbg_seed(const void *buf, int num)
{
return drbg_add(buf, num, num);
}
/* Implements the default OpenSSL RAND_status() method */
static int drbg_status(void)
{
int ret;
RAND_DRBG *drbg = RAND_DRBG_get0_master();
if (drbg == NULL)
return 0;
rand_drbg_lock(drbg);
ret = drbg->state == DRBG_READY ? 1 : 0;
rand_drbg_unlock(drbg);
return ret;
}
/*
* Get the master DRBG.
* Returns pointer to the DRBG on success, NULL on failure.
*
*/
RAND_DRBG *RAND_DRBG_get0_master(void)
{
if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
return NULL;
return master_drbg;
}
/*
* Get the public DRBG.
* Returns pointer to the DRBG on success, NULL on failure.
*/
RAND_DRBG *RAND_DRBG_get0_public(void)
{
RAND_DRBG *drbg;
if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
return NULL;
drbg = CRYPTO_THREAD_get_local(&public_drbg);
if (drbg == NULL) {
if (!ossl_init_thread_start(OPENSSL_INIT_THREAD_RAND))
return NULL;
drbg = drbg_setup(master_drbg);
CRYPTO_THREAD_set_local(&public_drbg, drbg);
}
return drbg;
}
/*
* Get the private DRBG.
* Returns pointer to the DRBG on success, NULL on failure.
*/
RAND_DRBG *RAND_DRBG_get0_private(void)
{
RAND_DRBG *drbg;
if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
return NULL;
drbg = CRYPTO_THREAD_get_local(&private_drbg);
if (drbg == NULL) {
if (!ossl_init_thread_start(OPENSSL_INIT_THREAD_RAND))
return NULL;
drbg = drbg_setup(master_drbg);
CRYPTO_THREAD_set_local(&private_drbg, drbg);
}
return drbg;
}
RAND_METHOD rand_meth = {
drbg_seed,
drbg_bytes,
NULL,
drbg_add,
drbg_bytes,
drbg_status
};
RAND_METHOD *RAND_OpenSSL(void)
{
return &rand_meth;
}
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