drbg_lib.c
/*
* Copyright 2011-2020 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (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.)
*/
typedef struct drbg_global_st {
/*
* 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.
*/
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.
*/
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.
*/
CRYPTO_THREAD_LOCAL private_drbg;
} DRBG_GLOBAL;
typedef struct drbg_nonce_global_st {
CRYPTO_RWLOCK *rand_nonce_lock;
int rand_nonce_count;
} DRBG_NONCE_GLOBAL;
/* NIST SP 800-90A DRBG recommends the use of a personalization string. */
static const char ossl_pers_string[] = DRBG_DEFAULT_PERS_STRING;
#define RAND_DRBG_TYPE_FLAGS ( \
RAND_DRBG_FLAG_MASTER | RAND_DRBG_FLAG_PUBLIC | RAND_DRBG_FLAG_PRIVATE )
#define RAND_DRBG_TYPE_MASTER 0
#define RAND_DRBG_TYPE_PUBLIC 1
#define RAND_DRBG_TYPE_PRIVATE 2
/* Defaults */
static int rand_drbg_type[3] = {
RAND_DRBG_TYPE, /* Master */
RAND_DRBG_TYPE, /* Public */
RAND_DRBG_TYPE /* Private */
};
static unsigned int rand_drbg_flags[3] = {
RAND_DRBG_FLAGS | RAND_DRBG_FLAG_MASTER, /* Master */
RAND_DRBG_FLAGS | RAND_DRBG_FLAG_PUBLIC, /* Public */
RAND_DRBG_FLAGS | RAND_DRBG_FLAG_PRIVATE /* Private */
};
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 | RAND_DRBG_FLAG_HMAC | RAND_DRBG_TYPE_FLAGS;
static RAND_DRBG *drbg_setup(OPENSSL_CTX *ctx, RAND_DRBG *parent, int drbg_type);
static RAND_DRBG *rand_drbg_new(OPENSSL_CTX *ctx,
int secure,
int type,
unsigned int flags,
RAND_DRBG *parent);
static int rand_drbg_set(RAND_DRBG *drbg, int type, unsigned int flags);
static int rand_drbg_init_method(RAND_DRBG *drbg);
static int is_ctr(int type)
{
switch (type) {
case NID_aes_128_ctr:
case NID_aes_192_ctr:
case NID_aes_256_ctr:
return 1;
default:
return 0;
}
}
static int is_digest(int type)
{
switch (type) {
case NID_sha1:
case NID_sha224:
case NID_sha256:
case NID_sha384:
case NID_sha512:
case NID_sha512_224:
case NID_sha512_256:
case NID_sha3_224:
case NID_sha3_256:
case NID_sha3_384:
case NID_sha3_512:
return 1;
default:
return 0;
}
}
/*
* Initialize the OPENSSL_CTX global DRBGs on first use.
* Returns the allocated global data on success or NULL on failure.
*/
static void *drbg_ossl_ctx_new(OPENSSL_CTX *libctx)
{
DRBG_GLOBAL *dgbl = OPENSSL_zalloc(sizeof(*dgbl));
if (dgbl == NULL)
return NULL;
#ifndef FIPS_MODULE
/*
* We need to ensure that base libcrypto thread handling has been
* initialised.
*/
OPENSSL_init_crypto(0, NULL);
#endif
if (!CRYPTO_THREAD_init_local(&dgbl->private_drbg, NULL))
goto err1;
if (!CRYPTO_THREAD_init_local(&dgbl->public_drbg, NULL))
goto err2;
dgbl->master_drbg = drbg_setup(libctx, NULL, RAND_DRBG_TYPE_MASTER);
if (dgbl->master_drbg == NULL)
goto err3;
return dgbl;
err3:
CRYPTO_THREAD_cleanup_local(&dgbl->public_drbg);
err2:
CRYPTO_THREAD_cleanup_local(&dgbl->private_drbg);
err1:
OPENSSL_free(dgbl);
return NULL;
}
static void drbg_ossl_ctx_free(void *vdgbl)
{
DRBG_GLOBAL *dgbl = vdgbl;
if (dgbl == NULL)
return;
RAND_DRBG_free(dgbl->master_drbg);
CRYPTO_THREAD_cleanup_local(&dgbl->private_drbg);
CRYPTO_THREAD_cleanup_local(&dgbl->public_drbg);
OPENSSL_free(dgbl);
}
static const OPENSSL_CTX_METHOD drbg_ossl_ctx_method = {
drbg_ossl_ctx_new,
drbg_ossl_ctx_free,
};
/*
* drbg_ossl_ctx_new() calls drgb_setup() which calls rand_drbg_get_nonce()
* which needs to get the rand_nonce_lock out of the OPENSSL_CTX...but since
* drbg_ossl_ctx_new() hasn't finished running yet we need the rand_nonce_lock
* to be in a different global data object. Otherwise we will go into an
* infinite recursion loop.
*/
static void *drbg_nonce_ossl_ctx_new(OPENSSL_CTX *libctx)
{
DRBG_NONCE_GLOBAL *dngbl = OPENSSL_zalloc(sizeof(*dngbl));
if (dngbl == NULL)
return NULL;
dngbl->rand_nonce_lock = CRYPTO_THREAD_lock_new();
if (dngbl->rand_nonce_lock == NULL) {
OPENSSL_free(dngbl);
return NULL;
}
return dngbl;
}
static void drbg_nonce_ossl_ctx_free(void *vdngbl)
{
DRBG_NONCE_GLOBAL *dngbl = vdngbl;
if (dngbl == NULL)
return;
CRYPTO_THREAD_lock_free(dngbl->rand_nonce_lock);
OPENSSL_free(dngbl);
}
static const OPENSSL_CTX_METHOD drbg_nonce_ossl_ctx_method = {
drbg_nonce_ossl_ctx_new,
drbg_nonce_ossl_ctx_free,
};
static DRBG_GLOBAL *drbg_get_global(OPENSSL_CTX *libctx)
{
return openssl_ctx_get_data(libctx, OPENSSL_CTX_DRBG_INDEX,
&drbg_ossl_ctx_method);
}
/* Implements the get_nonce() callback (see RAND_DRBG_set_callbacks()) */
size_t rand_drbg_get_nonce(RAND_DRBG *drbg,
unsigned char **pout,
int entropy, size_t min_len, size_t max_len)
{
size_t ret = 0;
RAND_POOL *pool;
DRBG_NONCE_GLOBAL *dngbl
= openssl_ctx_get_data(drbg->libctx, OPENSSL_CTX_DRBG_NONCE_INDEX,
&drbg_nonce_ossl_ctx_method);
struct {
void *instance;
int count;
} data;
if (dngbl == NULL)
return 0;
memset(&data, 0, sizeof(data));
pool = rand_pool_new(0, 0, min_len, max_len);
if (pool == NULL)
return 0;
if (rand_pool_add_nonce_data(pool) == 0)
goto err;
data.instance = drbg;
CRYPTO_atomic_add(&dngbl->rand_nonce_count, 1, &data.count,
dngbl->rand_nonce_lock);
if (rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0) == 0)
goto err;
ret = rand_pool_length(pool);
*pout = rand_pool_detach(pool);
err:
rand_pool_free(pool);
return ret;
}
/*
* Implements the cleanup_nonce() callback (see RAND_DRBG_set_callbacks())
*
*/
void rand_drbg_cleanup_nonce(RAND_DRBG *drbg,
unsigned char *out, size_t outlen)
{
OPENSSL_clear_free(out, outlen);
}
/*
* Set the |drbg|'s callback data pointer for the entropy and nonce callbacks
*
* The ownership of the context data remains with the caller,
* i.e., it is the caller's responsibility to keep it available as long
* as it is need by the callbacks and free it after use.
*
* Setting the callback data 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_callback_data(RAND_DRBG *drbg, void *data)
{
if (drbg->state != DRBG_UNINITIALISED
|| drbg->parent != NULL)
return 0;
drbg->callback_data = data;
return 1;
}
/* Retrieve the callback data pointer */
void *RAND_DRBG_get_callback_data(RAND_DRBG *drbg)
{
return drbg->callback_data;
}
/*
* 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)
{
return rand_drbg_set(drbg, type, flags) && rand_drbg_init_method(drbg);
}
static int rand_drbg_set(RAND_DRBG *drbg, int type, unsigned int flags)
{
if (type == 0 && flags == 0) {
type = rand_drbg_type[RAND_DRBG_TYPE_MASTER];
flags = rand_drbg_flags[RAND_DRBG_TYPE_MASTER];
}
/* If set is called multiple times - clear the old one */
if (drbg->type != 0 && (type != drbg->type || flags != drbg->flags)) {
if (drbg->meth != NULL)
drbg->meth->uninstantiate(drbg);
rand_pool_free(drbg->adin_pool);
drbg->adin_pool = NULL;
}
drbg->state = DRBG_UNINITIALISED;
drbg->flags = flags;
drbg->type = type;
drbg->meth = NULL;
if (type == 0 || is_ctr(type) || is_digest(type))
return 1;
drbg->type = 0;
drbg->flags = 0;
RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_UNSUPPORTED_DRBG_TYPE);
return 0;
}
static int rand_drbg_init_method(RAND_DRBG *drbg)
{
int ret;
if (drbg->meth != NULL)
return 1;
if (is_ctr(drbg->type)) {
ret = drbg_ctr_init(drbg);
} else if (is_digest(drbg->type)) {
if (drbg->flags & RAND_DRBG_FLAG_HMAC)
ret = drbg_hmac_init(drbg);
else
ret = drbg_hash_init(drbg);
} else {
/* other cases should already be excluded */
RANDerr(RAND_F_RAND_DRBG_INIT_METHOD, ERR_R_INTERNAL_ERROR);
drbg->type = 0;
drbg->flags = 0;
return 0;
}
if (ret == 0) {
drbg->state = DRBG_ERROR;
RANDerr(RAND_F_RAND_DRBG_INIT_METHOD, 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 all;
if (!(is_digest(type) || is_ctr(type))) {
RANDerr(RAND_F_RAND_DRBG_SET_DEFAULTS, RAND_R_UNSUPPORTED_DRBG_TYPE);
return 0;
}
if ((flags & ~rand_drbg_used_flags) != 0) {
RANDerr(RAND_F_RAND_DRBG_SET_DEFAULTS, RAND_R_UNSUPPORTED_DRBG_FLAGS);
return 0;
}
all = ((flags & RAND_DRBG_TYPE_FLAGS) == 0);
if (all || (flags & RAND_DRBG_FLAG_MASTER) != 0) {
rand_drbg_type[RAND_DRBG_TYPE_MASTER] = type;
rand_drbg_flags[RAND_DRBG_TYPE_MASTER] = flags | RAND_DRBG_FLAG_MASTER;
}
if (all || (flags & RAND_DRBG_FLAG_PUBLIC) != 0) {
rand_drbg_type[RAND_DRBG_TYPE_PUBLIC] = type;
rand_drbg_flags[RAND_DRBG_TYPE_PUBLIC] = flags | RAND_DRBG_FLAG_PUBLIC;
}
if (all || (flags & RAND_DRBG_FLAG_PRIVATE) != 0) {
rand_drbg_type[RAND_DRBG_TYPE_PRIVATE] = type;
rand_drbg_flags[RAND_DRBG_TYPE_PRIVATE] = flags | RAND_DRBG_FLAG_PRIVATE;
}
return 1;
}
/*
* 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(OPENSSL_CTX *ctx,
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->libctx = ctx;
drbg->secure = secure && CRYPTO_secure_allocated(drbg);
drbg->fork_id = openssl_get_fork_id();
drbg->parent = parent;
if (parent == NULL) {
#ifdef FIPS_MODULE
drbg->get_entropy = rand_crngt_get_entropy;
drbg->cleanup_entropy = rand_crngt_cleanup_entropy;
#else
drbg->get_entropy = rand_drbg_get_entropy;
drbg->cleanup_entropy = rand_drbg_cleanup_entropy;
#endif
#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_ex(OPENSSL_CTX *ctx, int type, unsigned int flags,
RAND_DRBG *parent)
{
return rand_drbg_new(ctx, 0, type, flags, parent);
}
RAND_DRBG *RAND_DRBG_new(int type, unsigned int flags, RAND_DRBG *parent)
{
return RAND_DRBG_new_ex(NULL, type, flags, parent);
}
RAND_DRBG *RAND_DRBG_secure_new_ex(OPENSSL_CTX *ctx, int type,
unsigned int flags, RAND_DRBG *parent)
{
return rand_drbg_new(ctx, 1, type, flags, parent);
}
RAND_DRBG *RAND_DRBG_secure_new(int type, unsigned int flags, RAND_DRBG *parent)
{
return RAND_DRBG_secure_new_ex(NULL, 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);
#ifndef FIPS_MODULE
CRYPTO_free_ex_data(CRYPTO_EX_INDEX_RAND_DRBG, drbg, &drbg->ex_data);
#endif
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, min_entropylen, max_entropylen;
if (drbg->meth == NULL && !rand_drbg_init_method(drbg)) {
RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
RAND_R_NO_DRBG_IMPLEMENTATION_SELECTED);
goto end;
}
min_entropy = drbg->strength;
min_entropylen = drbg->min_entropylen;
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->state != DRBG_UNINITIALISED) {
if (drbg->state == DRBG_ERROR)
RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_IN_ERROR_STATE);
else
RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, 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;
}
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) {
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->reseed_gen_counter = 1;
drbg->reseed_time = time(NULL);
tsan_store(&drbg->reseed_prop_counter, drbg->reseed_next_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)
{
int index = -1, type, flags;
if (drbg->meth != NULL) {
drbg->meth->uninstantiate(drbg);
drbg->meth = NULL;
}
/* The reset uses the default values for type and flags */
if (drbg->flags & RAND_DRBG_FLAG_MASTER)
index = RAND_DRBG_TYPE_MASTER;
else if (drbg->flags & RAND_DRBG_FLAG_PRIVATE)
index = RAND_DRBG_TYPE_PRIVATE;
else if (drbg->flags & RAND_DRBG_FLAG_PUBLIC)
index = RAND_DRBG_TYPE_PUBLIC;
if (index != -1) {
flags = rand_drbg_flags[index];
type = rand_drbg_type[index];
} else {
flags = drbg->flags;
type = drbg->type;
}
return rand_drbg_set(drbg, type, 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;
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) {
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->reseed_gen_counter = 1;
drbg->reseed_time = time(NULL);
tsan_store(&drbg->reseed_prop_counter, drbg->reseed_next_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 */
RAND_DRBG_reseed(drbg, NULL, 0, 0);
}
}
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->reseed_gen_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->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;
}
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->reseed_gen_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
|| drbg->parent != NULL)
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;
}
#ifndef FIPS_MODULE
/*
* 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);
}
#endif
/*
* 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(OPENSSL_CTX *ctx, RAND_DRBG *parent, int drbg_type)
{
RAND_DRBG *drbg;
drbg = RAND_DRBG_secure_new_ex(ctx, rand_drbg_type[drbg_type],
rand_drbg_flags[drbg_type], 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 seed propagation */
tsan_store(&drbg->reseed_prop_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;
}
static void drbg_delete_thread_state(void *arg)
{
OPENSSL_CTX *ctx = arg;
DRBG_GLOBAL *dgbl = drbg_get_global(ctx);
RAND_DRBG *drbg;
if (dgbl == NULL)
return;
drbg = CRYPTO_THREAD_get_local(&dgbl->public_drbg);
CRYPTO_THREAD_set_local(&dgbl->public_drbg, NULL);
RAND_DRBG_free(drbg);
drbg = CRYPTO_THREAD_get_local(&dgbl->private_drbg);
CRYPTO_THREAD_set_local(&dgbl->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;
#ifdef FIPS_MODULE
/*
* NIST SP-800-90A mandates that entropy *shall not* be provided
* by the consuming application. By setting the randomness to zero,
* we ensure that the buffer contents will be added to the internal
* state of the DRBG only as additional data.
*
* (NIST SP-800-90Ar1, Sections 9.1 and 9.2)
*/
randomness = 0.0;
#endif
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 *OPENSSL_CTX_get0_master_drbg(OPENSSL_CTX *ctx)
{
DRBG_GLOBAL *dgbl = drbg_get_global(ctx);
if (dgbl == NULL)
return NULL;
return dgbl->master_drbg;
}
RAND_DRBG *RAND_DRBG_get0_master(void)
{
return OPENSSL_CTX_get0_master_drbg(NULL);
}
/*
* Get the public DRBG.
* Returns pointer to the DRBG on success, NULL on failure.
*/
RAND_DRBG *OPENSSL_CTX_get0_public_drbg(OPENSSL_CTX *ctx)
{
DRBG_GLOBAL *dgbl = drbg_get_global(ctx);
RAND_DRBG *drbg;
if (dgbl == NULL)
return NULL;
drbg = CRYPTO_THREAD_get_local(&dgbl->public_drbg);
if (drbg == NULL) {
ctx = openssl_ctx_get_concrete(ctx);
/*
* If the private_drbg is also NULL then this is the first time we've
* used this thread.
*/
if (CRYPTO_THREAD_get_local(&dgbl->private_drbg) == NULL
&& !ossl_init_thread_start(NULL, ctx, drbg_delete_thread_state))
return NULL;
drbg = drbg_setup(ctx, dgbl->master_drbg, RAND_DRBG_TYPE_PUBLIC);
CRYPTO_THREAD_set_local(&dgbl->public_drbg, drbg);
}
return drbg;
}
RAND_DRBG *RAND_DRBG_get0_public(void)
{
return OPENSSL_CTX_get0_public_drbg(NULL);
}
/*
* Get the private DRBG.
* Returns pointer to the DRBG on success, NULL on failure.
*/
RAND_DRBG *OPENSSL_CTX_get0_private_drbg(OPENSSL_CTX *ctx)
{
DRBG_GLOBAL *dgbl = drbg_get_global(ctx);
RAND_DRBG *drbg;
if (dgbl == NULL)
return NULL;
drbg = CRYPTO_THREAD_get_local(&dgbl->private_drbg);
if (drbg == NULL) {
ctx = openssl_ctx_get_concrete(ctx);
/*
* If the public_drbg is also NULL then this is the first time we've
* used this thread.
*/
if (CRYPTO_THREAD_get_local(&dgbl->public_drbg) == NULL
&& !ossl_init_thread_start(NULL, ctx, drbg_delete_thread_state))
return NULL;
drbg = drbg_setup(ctx, dgbl->master_drbg, RAND_DRBG_TYPE_PRIVATE);
CRYPTO_THREAD_set_local(&dgbl->private_drbg, drbg);
}
return drbg;
}
RAND_DRBG *RAND_DRBG_get0_private(void)
{
return OPENSSL_CTX_get0_private_drbg(NULL);
}
RAND_METHOD rand_meth = {
drbg_seed,
drbg_bytes,
NULL,
drbg_add,
drbg_bytes,
drbg_status
};
RAND_METHOD *RAND_OpenSSL(void)
{
#ifndef FIPS_MODULE
return &rand_meth;
#else
return NULL;
#endif
}
