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/*
* Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
* Copyright (c) 2019, Oracle and/or its affiliates. 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
*/
/*
* Implementation of the FIPS 140-2 section 4.9.2 Conditional Tests.
*/
#include <string.h>
#include <openssl/evp.h>
#include <openssl/core_dispatch.h>
#include <openssl/params.h>
#include <openssl/self_test.h>
#include "prov/providercommon.h"
#include "prov/provider_ctx.h"
#include "internal/cryptlib.h"
#include "crypto/rand_pool.h"
#include "drbg_local.h"
#include "prov/seeding.h"
typedef struct crng_test_global_st {
unsigned char crngt_prev[EVP_MAX_MD_SIZE];
EVP_MD *md;
int preloaded;
CRYPTO_RWLOCK *lock;
} CRNG_TEST_GLOBAL;
static int crngt_get_entropy(PROV_CTX *provctx, const EVP_MD *digest,
unsigned char *buf, unsigned char *md,
unsigned int *md_size)
{
int r;
size_t n;
unsigned char *p;
n = ossl_prov_get_entropy(provctx, &p, 0, CRNGT_BUFSIZ, CRNGT_BUFSIZ);
if (n == CRNGT_BUFSIZ) {
r = EVP_Digest(p, CRNGT_BUFSIZ, md, md_size, digest, NULL);
if (r != 0)
memcpy(buf, p, CRNGT_BUFSIZ);
ossl_prov_cleanup_entropy(provctx, p, n);
return r != 0;
}
if (n != 0)
ossl_prov_cleanup_entropy(provctx, p, n);
return 0;
}
static void rand_crng_ossl_ctx_free(void *vcrngt_glob)
{
CRNG_TEST_GLOBAL *crngt_glob = vcrngt_glob;
CRYPTO_THREAD_lock_free(crngt_glob->lock);
EVP_MD_free(crngt_glob->md);
OPENSSL_free(crngt_glob);
}
static void *rand_crng_ossl_ctx_new(OSSL_LIB_CTX *ctx)
{
CRNG_TEST_GLOBAL *crngt_glob = OPENSSL_zalloc(sizeof(*crngt_glob));
if (crngt_glob == NULL)
return NULL;
if ((crngt_glob->md = EVP_MD_fetch(ctx, "SHA256", "")) == NULL) {
OPENSSL_free(crngt_glob);
return NULL;
}
if ((crngt_glob->lock = CRYPTO_THREAD_lock_new()) == NULL) {
EVP_MD_free(crngt_glob->md);
OPENSSL_free(crngt_glob);
return NULL;
}
return crngt_glob;
}
static const OSSL_LIB_CTX_METHOD rand_crng_ossl_ctx_method = {
OSSL_LIB_CTX_METHOD_DEFAULT_PRIORITY,
rand_crng_ossl_ctx_new,
rand_crng_ossl_ctx_free,
};
static int prov_crngt_compare_previous(const unsigned char *prev,
const unsigned char *cur,
size_t sz)
{
const int res = memcmp(prev, cur, sz) != 0;
if (!res)
ossl_set_error_state(OSSL_SELF_TEST_TYPE_CRNG);
return res;
}
size_t ossl_crngt_get_entropy(PROV_DRBG *drbg,
unsigned char **pout,
int entropy, size_t min_len, size_t max_len,
int prediction_resistance)
{
unsigned char md[EVP_MAX_MD_SIZE];
unsigned char buf[CRNGT_BUFSIZ];
unsigned char *ent, *entp, *entbuf;
unsigned int sz;
size_t bytes_needed;
size_t r = 0, s, t;
int crng_test_pass = 1;
OSSL_LIB_CTX *libctx = ossl_prov_ctx_get0_libctx(drbg->provctx);
CRNG_TEST_GLOBAL *crngt_glob
= ossl_lib_ctx_get_data(libctx, OSSL_LIB_CTX_RAND_CRNGT_INDEX,
&rand_crng_ossl_ctx_method);
OSSL_CALLBACK *stcb = NULL;
void *stcbarg = NULL;
OSSL_SELF_TEST *st = NULL;
if (crngt_glob == NULL)
return 0;
if (!CRYPTO_THREAD_write_lock(crngt_glob->lock))
return 0;
if (!crngt_glob->preloaded) {
if (!crngt_get_entropy(drbg->provctx, crngt_glob->md, buf,
crngt_glob->crngt_prev, NULL)) {
OPENSSL_cleanse(buf, sizeof(buf));
goto unlock_return;
}
crngt_glob->preloaded = 1;
}
/*
* Calculate how many bytes of seed material we require, rounded up
* to the nearest byte. If the entropy is of less than full quality,
* the amount required should be scaled up appropriately here.
*/
bytes_needed = (entropy + 7) / 8;
if (bytes_needed < min_len)
bytes_needed = min_len;
if (bytes_needed > max_len)
goto unlock_return;
entp = ent = OPENSSL_secure_malloc(bytes_needed);
if (ent == NULL)
goto unlock_return;
OSSL_SELF_TEST_get_callback(libctx, &stcb, &stcbarg);
if (stcb != NULL) {
st = OSSL_SELF_TEST_new(stcb, stcbarg);
if (st == NULL)
goto err;
OSSL_SELF_TEST_onbegin(st, OSSL_SELF_TEST_TYPE_CRNG,
OSSL_SELF_TEST_DESC_RNG);
}
for (t = bytes_needed; t > 0;) {
/* Care needs to be taken to avoid overrunning the buffer */
s = t >= CRNGT_BUFSIZ ? CRNGT_BUFSIZ : t;
entbuf = t >= CRNGT_BUFSIZ ? entp : buf;
if (!crngt_get_entropy(drbg->provctx, crngt_glob->md, entbuf, md, &sz))
goto err;
if (t < CRNGT_BUFSIZ)
memcpy(entp, buf, t);
/* Force a failure here if the callback returns 1 */
if (OSSL_SELF_TEST_oncorrupt_byte(st, md))
memcpy(md, crngt_glob->crngt_prev, sz);
if (!prov_crngt_compare_previous(crngt_glob->crngt_prev, md, sz)) {
crng_test_pass = 0;
goto err;
}
/* Update for next block */
memcpy(crngt_glob->crngt_prev, md, sz);
entp += s;
t -= s;
}
r = bytes_needed;
*pout = ent;
ent = NULL;
err:
OSSL_SELF_TEST_onend(st, crng_test_pass);
OSSL_SELF_TEST_free(st);
OPENSSL_secure_clear_free(ent, bytes_needed);
unlock_return:
CRYPTO_THREAD_unlock(crngt_glob->lock);
return r;
}
void ossl_crngt_cleanup_entropy(ossl_unused PROV_DRBG *drbg,
unsigned char *out, size_t outlen)
{
OPENSSL_secure_clear_free(out, outlen);
}
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