6969a3f49a
The DRBG callbacks 'get_entropy()' and 'cleanup_entropy()' are designed in such a way that the randomness buffer does not have to be allocated by the calling function. It receives the address of a dynamically allocated buffer from get_entropy() and returns this address to cleanup_entropy(), where it is freed. If these two calls are properly paired, the address can be stored in a stack local variable of the calling function, so there is no need for having a 'randomness' member (and a 'filled' member) in 'RAND_DRBG'. Reviewed-by: Paul Dale <paul.dale@oracle.com> Reviewed-by: Rich Salz <rsalz@openssl.org> (Merged from https://github.com/openssl/openssl/pull/4266)
423 lines
12 KiB
C
423 lines
12 KiB
C
/*
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* Copyright 2011-2017 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#include <string.h>
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#include <openssl/crypto.h>
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#include <openssl/err.h>
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#include <openssl/rand.h>
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#include "rand_lcl.h"
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/*
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* Support framework for NIST SP 800-90A DRBG, AES-CTR mode.
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* The RAND_DRBG is OpenSSL's pointer to an instance of the DRBG.
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*
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* The OpenSSL model is to have new and free functions, and that new
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* does all initialization. That is not the NIST model, which has
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* instantiation and un-instantiate, and re-use within a new/free
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* lifecycle. (No doubt this comes from the desire to support hardware
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* DRBG, where allocation of resources on something like an HSM is
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* a much bigger deal than just re-setting an allocated resource.)
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*/
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/*
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* Set/initialize |drbg| to be of type |nid|, with optional |flags|.
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* Return -2 if the type is not supported, 1 on success and -1 on
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* failure.
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*/
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int RAND_DRBG_set(RAND_DRBG *drbg, int nid, unsigned int flags)
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{
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int ret = 1;
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drbg->state = DRBG_UNINITIALISED;
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drbg->flags = flags;
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drbg->nid = nid;
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switch (nid) {
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default:
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RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_UNSUPPORTED_DRBG_TYPE);
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return -2;
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case 0:
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/* Uninitialized; that's okay. */
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return 1;
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case NID_aes_128_ctr:
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case NID_aes_192_ctr:
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case NID_aes_256_ctr:
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ret = ctr_init(drbg);
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break;
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}
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if (ret < 0)
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RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_ERROR_INITIALISING_DRBG);
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return ret;
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}
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/*
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* Allocate memory and initialize a new DRBG. The |parent|, if not
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* NULL, will be used to auto-seed this RAND_DRBG as needed.
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*/
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RAND_DRBG *RAND_DRBG_new(int type, unsigned int flags, RAND_DRBG *parent)
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{
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RAND_DRBG *drbg = OPENSSL_zalloc(sizeof(*drbg));
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if (drbg == NULL) {
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RANDerr(RAND_F_RAND_DRBG_NEW, ERR_R_MALLOC_FAILURE);
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goto err;
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}
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drbg->size = RANDOMNESS_NEEDED;
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drbg->fork_count = rand_fork_count;
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drbg->parent = parent;
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if (RAND_DRBG_set(drbg, type, flags) < 0)
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goto err;
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if (parent != NULL) {
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if (parent->state == DRBG_UNINITIALISED
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&& RAND_DRBG_instantiate(parent, NULL, 0) == 0)
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goto err;
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if (!RAND_DRBG_set_callbacks(drbg, drbg_entropy_from_parent,
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drbg_release_entropy,
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NULL, NULL)
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/*
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* Add in our address. Note we are adding the pointer
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* itself, not its contents!
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*/
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|| !RAND_DRBG_instantiate(drbg,
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(unsigned char*)&drbg, sizeof(drbg)))
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goto err;
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}
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return drbg;
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err:
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OPENSSL_free(drbg);
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return NULL;
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}
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RAND_DRBG *RAND_DRBG_get0_global(void)
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{
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return &rand_drbg;
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}
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/*
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* Uninstantiate |drbg| and free all memory.
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*/
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void RAND_DRBG_free(RAND_DRBG *drbg)
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{
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/* The global DRBG is free'd by rand_cleanup_int() */
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if (drbg == NULL || drbg == &rand_drbg)
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return;
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ctr_uninstantiate(drbg);
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CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DRBG, drbg, &drbg->ex_data);
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OPENSSL_clear_free(drbg, sizeof(*drbg));
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}
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/*
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* Instantiate |drbg|, after it has been initialized. Use |pers| and
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* |perslen| as prediction-resistance input.
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*/
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int RAND_DRBG_instantiate(RAND_DRBG *drbg,
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const unsigned char *pers, size_t perslen)
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{
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unsigned char *nonce = NULL, *entropy = NULL;
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size_t noncelen = 0, entropylen = 0;
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if (perslen > drbg->max_perslen) {
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RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
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RAND_R_PERSONALISATION_STRING_TOO_LONG);
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goto end;
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}
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if (drbg->state != DRBG_UNINITIALISED) {
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RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
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drbg->state == DRBG_ERROR ? RAND_R_IN_ERROR_STATE
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: RAND_R_ALREADY_INSTANTIATED);
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goto end;
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}
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drbg->state = DRBG_ERROR;
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if (drbg->get_entropy != NULL)
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entropylen = drbg->get_entropy(drbg, &entropy, drbg->strength,
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drbg->min_entropylen, drbg->max_entropylen);
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if (entropylen < drbg->min_entropylen || entropylen > drbg->max_entropylen) {
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RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_ENTROPY);
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goto end;
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}
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if (drbg->max_noncelen > 0 && drbg->get_nonce != NULL) {
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noncelen = drbg->get_nonce(drbg, &nonce, drbg->strength / 2,
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drbg->min_noncelen, drbg->max_noncelen);
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if (noncelen < drbg->min_noncelen || noncelen > drbg->max_noncelen) {
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RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_NONCE);
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goto end;
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}
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}
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if (!ctr_instantiate(drbg, entropy, entropylen,
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nonce, noncelen, pers, perslen)) {
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RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_INSTANTIATING_DRBG);
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goto end;
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}
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drbg->state = DRBG_READY;
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drbg->reseed_counter = 1;
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end:
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if (entropy != NULL && drbg->cleanup_entropy != NULL)
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drbg->cleanup_entropy(drbg, entropy, entropylen);
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if (nonce != NULL && drbg->cleanup_nonce!= NULL )
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drbg->cleanup_nonce(drbg, nonce, noncelen);
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if (drbg->state == DRBG_READY)
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return 1;
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return 0;
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}
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/*
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* Uninstantiate |drbg|. Must be instantiated before it can be used.
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*/
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int RAND_DRBG_uninstantiate(RAND_DRBG *drbg)
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{
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int ret = ctr_uninstantiate(drbg);
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OPENSSL_cleanse(&drbg->ctr, sizeof(drbg->ctr));
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drbg->state = DRBG_UNINITIALISED;
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return ret;
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}
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/*
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* Mix in the specified data to reseed |drbg|.
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*/
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int RAND_DRBG_reseed(RAND_DRBG *drbg,
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const unsigned char *adin, size_t adinlen)
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{
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unsigned char *entropy = NULL;
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size_t entropylen = 0;
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if (drbg->state == DRBG_ERROR) {
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RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_IN_ERROR_STATE);
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return 0;
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}
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if (drbg->state == DRBG_UNINITIALISED) {
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RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_NOT_INSTANTIATED);
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return 0;
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}
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if (adin == NULL)
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adinlen = 0;
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else if (adinlen > drbg->max_adinlen) {
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RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
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return 0;
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}
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drbg->state = DRBG_ERROR;
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if (drbg->get_entropy != NULL)
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entropylen = drbg->get_entropy(drbg, &entropy, drbg->strength,
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drbg->min_entropylen, drbg->max_entropylen);
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if (entropylen < drbg->min_entropylen || entropylen > drbg->max_entropylen) {
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RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ERROR_RETRIEVING_ENTROPY);
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goto end;
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}
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if (!ctr_reseed(drbg, entropy, entropylen, adin, adinlen))
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goto end;
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drbg->state = DRBG_READY;
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drbg->reseed_counter = 1;
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end:
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if (entropy != NULL && drbg->cleanup_entropy != NULL)
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drbg->cleanup_entropy(drbg, entropy, entropylen);
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if (drbg->state == DRBG_READY)
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return 1;
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return 0;
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}
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/*
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* Generate |outlen| bytes into the buffer at |out|. Reseed if we need
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* to or if |prediction_resistance| is set. Additional input can be
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* sent in |adin| and |adinlen|.
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*/
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int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen,
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int prediction_resistance,
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const unsigned char *adin, size_t adinlen)
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{
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if (drbg->state == DRBG_ERROR) {
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RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_IN_ERROR_STATE);
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return 0;
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}
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if (drbg->state == DRBG_UNINITIALISED) {
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RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_NOT_INSTANTIATED);
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return 0;
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}
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if (outlen > drbg->max_request) {
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RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_REQUEST_TOO_LARGE_FOR_DRBG);
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return 0;
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}
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if (adinlen > drbg->max_adinlen) {
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RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
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return 0;
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}
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if (drbg->fork_count != rand_fork_count) {
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drbg->fork_count = rand_fork_count;
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drbg->state = DRBG_RESEED;
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}
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if (drbg->reseed_counter >= drbg->reseed_interval)
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drbg->state = DRBG_RESEED;
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if (drbg->state == DRBG_RESEED || prediction_resistance) {
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if (!RAND_DRBG_reseed(drbg, adin, adinlen)) {
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RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_RESEED_ERROR);
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return 0;
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}
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adin = NULL;
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adinlen = 0;
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}
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if (!ctr_generate(drbg, out, outlen, adin, adinlen)) {
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drbg->state = DRBG_ERROR;
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RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_GENERATE_ERROR);
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return 0;
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}
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if (drbg->reseed_counter >= drbg->reseed_interval)
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drbg->state = DRBG_RESEED;
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else
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drbg->reseed_counter++;
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return 1;
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}
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/*
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* Set the callbacks for entropy and nonce. We currently don't use
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* the nonce; that's mainly for the KATs
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*/
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int RAND_DRBG_set_callbacks(RAND_DRBG *drbg,
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RAND_DRBG_get_entropy_fn cb_get_entropy,
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RAND_DRBG_cleanup_entropy_fn cb_cleanup_entropy,
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RAND_DRBG_get_nonce_fn cb_get_nonce,
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RAND_DRBG_cleanup_nonce_fn cb_cleanup_nonce)
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{
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if (drbg->state != DRBG_UNINITIALISED)
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return 0;
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drbg->get_entropy = cb_get_entropy;
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drbg->cleanup_entropy = cb_cleanup_entropy;
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drbg->get_nonce = cb_get_nonce;
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drbg->cleanup_nonce = cb_cleanup_nonce;
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return 1;
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}
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/*
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* Set the reseed interval.
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*/
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int RAND_DRBG_set_reseed_interval(RAND_DRBG *drbg, int interval)
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{
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if (interval < 0 || interval > MAX_RESEED)
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return 0;
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drbg->reseed_interval = interval;
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return 1;
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}
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/*
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* Get and set the EXDATA
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*/
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int RAND_DRBG_set_ex_data(RAND_DRBG *drbg, int idx, void *arg)
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{
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return CRYPTO_set_ex_data(&drbg->ex_data, idx, arg);
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}
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void *RAND_DRBG_get_ex_data(const RAND_DRBG *drbg, int idx)
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{
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return CRYPTO_get_ex_data(&drbg->ex_data, idx);
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}
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/*
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* The following functions provide a RAND_METHOD that works on the
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* global DRBG. They lock.
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*/
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static int drbg_bytes(unsigned char *out, int count)
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{
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int ret = 0;
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size_t chunk;
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CRYPTO_THREAD_write_lock(rand_drbg.lock);
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if (rand_drbg.state == DRBG_UNINITIALISED
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&& RAND_DRBG_instantiate(&rand_drbg, NULL, 0) == 0)
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goto err;
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for ( ; count > 0; count -= chunk, out += chunk) {
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chunk = count;
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if (chunk > rand_drbg.max_request)
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chunk = rand_drbg.max_request;
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ret = RAND_DRBG_generate(&rand_drbg, out, chunk, 0, NULL, 0);
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if (!ret)
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goto err;
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}
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ret = 1;
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err:
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CRYPTO_THREAD_unlock(rand_drbg.lock);
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return ret;
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}
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static int drbg_add(const void *buf, int num, double randomness)
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{
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unsigned char *in = (unsigned char *)buf;
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unsigned char *out, *end;
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CRYPTO_THREAD_write_lock(rand_bytes.lock);
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out = &rand_bytes.buff[rand_bytes.curr];
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end = &rand_bytes.buff[rand_bytes.size];
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/* Copy whatever fits into the end of the buffer. */
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for ( ; --num >= 0 && out < end; rand_bytes.curr++)
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*out++ = *in++;
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/* XOR any the leftover. */
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while (num > 0) {
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for (out = rand_bytes.buff; --num >= 0 && out < end; )
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*out++ ^= *in++;
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}
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CRYPTO_THREAD_unlock(rand_bytes.lock);
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return 1;
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}
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static int drbg_seed(const void *buf, int num)
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{
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return drbg_add(buf, num, num);
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}
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static int drbg_status(void)
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{
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int ret;
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CRYPTO_THREAD_write_lock(rand_drbg.lock);
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if (rand_drbg.state == DRBG_UNINITIALISED)
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RAND_DRBG_instantiate(&rand_drbg, NULL, 0);
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ret = rand_drbg.state == DRBG_READY ? 1 : 0;
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CRYPTO_THREAD_unlock(rand_drbg.lock);
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return ret;
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}
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RAND_DRBG rand_drbg; /* The default global DRBG. */
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RAND_DRBG priv_drbg; /* The global private-key DRBG. */
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RAND_METHOD rand_meth = {
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drbg_seed,
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drbg_bytes,
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NULL,
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drbg_add,
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drbg_bytes,
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drbg_status
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};
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RAND_METHOD *RAND_OpenSSL(void)
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{
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return &rand_meth;
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}
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