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|
/*
* Copyright 1995-2016 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 <stdio.h>
#include <string.h>
#include "e_os.h"
#if !(defined(OPENSSL_SYS_WIN32) || defined(OPENSSL_SYS_VXWORKS) || defined(OPENSSL_SYS_DSPBIOS))
# include <sys/time.h>
#endif
#if defined(OPENSSL_SYS_VXWORKS)
# include <time.h>
#endif
#include <openssl/opensslconf.h>
#include <openssl/crypto.h>
#include <openssl/rand.h>
#include <openssl/async.h>
#include "rand_lcl.h"
#include <openssl/err.h>
#include <internal/thread_once.h>
#ifdef OPENSSL_FIPS
# include <openssl/fips.h>
#endif
#if defined(BN_DEBUG) || defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION)
# define PREDICT
#endif
/* #define PREDICT 1 */
#define STATE_SIZE 1023
static size_t state_num = 0, state_index = 0;
static unsigned char state[STATE_SIZE + MD_DIGEST_LENGTH];
static unsigned char md[MD_DIGEST_LENGTH];
static long md_count[2] = { 0, 0 };
static double entropy = 0;
static int initialized = 0;
static CRYPTO_RWLOCK *rand_lock = NULL;
static CRYPTO_RWLOCK *rand_tmp_lock = NULL;
static CRYPTO_ONCE rand_lock_init = CRYPTO_ONCE_STATIC_INIT;
/* May be set only when a thread holds rand_lock (to prevent double locking) */
static unsigned int crypto_lock_rand = 0;
/* access to locking_threadid is synchronized by rand_tmp_lock */
/* valid iff crypto_lock_rand is set */
static CRYPTO_THREAD_ID locking_threadid;
#ifdef PREDICT
int rand_predictable = 0;
#endif
static int rand_hw_seed(EVP_MD_CTX *ctx);
static void rand_cleanup(void);
static int rand_seed(const void *buf, int num);
static int rand_add(const void *buf, int num, double add_entropy);
static int rand_bytes(unsigned char *buf, int num, int pseudo);
static int rand_nopseudo_bytes(unsigned char *buf, int num);
#if OPENSSL_API_COMPAT < 0x10100000L
static int rand_pseudo_bytes(unsigned char *buf, int num);
#endif
static int rand_status(void);
static RAND_METHOD rand_meth = {
rand_seed,
rand_nopseudo_bytes,
rand_cleanup,
rand_add,
#if OPENSSL_API_COMPAT < 0x10100000L
rand_pseudo_bytes,
#else
NULL,
#endif
rand_status
};
DEFINE_RUN_ONCE_STATIC(do_rand_lock_init)
{
OPENSSL_init_crypto(0, NULL);
rand_lock = CRYPTO_THREAD_lock_new();
rand_tmp_lock = CRYPTO_THREAD_lock_new();
return rand_lock != NULL && rand_tmp_lock != NULL;
}
RAND_METHOD *RAND_OpenSSL(void)
{
return (&rand_meth);
}
static void rand_cleanup(void)
{
OPENSSL_cleanse(state, sizeof(state));
state_num = 0;
state_index = 0;
OPENSSL_cleanse(md, MD_DIGEST_LENGTH);
md_count[0] = 0;
md_count[1] = 0;
entropy = 0;
initialized = 0;
CRYPTO_THREAD_lock_free(rand_lock);
CRYPTO_THREAD_lock_free(rand_tmp_lock);
}
static int rand_add(const void *buf, int num, double add)
{
int i, j, k, st_idx;
long md_c[2];
unsigned char local_md[MD_DIGEST_LENGTH];
EVP_MD_CTX *m;
int do_not_lock;
int rv = 0;
if (!num)
return 1;
#ifdef PREDICT
if (rand_predictable)
return 1;
#endif
/*
* (Based on the rand(3) manpage)
*
* The input is chopped up into units of 20 bytes (or less for
* the last block). Each of these blocks is run through the hash
* function as follows: The data passed to the hash function
* is the current 'md', the same number of bytes from the 'state'
* (the location determined by in incremented looping index) as
* the current 'block', the new key data 'block', and 'count'
* (which is incremented after each use).
* The result of this is kept in 'md' and also xored into the
* 'state' at the same locations that were used as input into the
* hash function.
*/
m = EVP_MD_CTX_new();
if (m == NULL)
goto err;
if (!RUN_ONCE(&rand_lock_init, do_rand_lock_init))
goto err;
/* check if we already have the lock */
if (crypto_lock_rand) {
CRYPTO_THREAD_ID cur = CRYPTO_THREAD_get_current_id();
CRYPTO_THREAD_read_lock(rand_tmp_lock);
do_not_lock = CRYPTO_THREAD_compare_id(locking_threadid, cur);
CRYPTO_THREAD_unlock(rand_tmp_lock);
} else
do_not_lock = 0;
if (!do_not_lock)
CRYPTO_THREAD_write_lock(rand_lock);
st_idx = state_index;
/*
* use our own copies of the counters so that even if a concurrent thread
* seeds with exactly the same data and uses the same subarray there's
* _some_ difference
*/
md_c[0] = md_count[0];
md_c[1] = md_count[1];
memcpy(local_md, md, sizeof md);
/* state_index <= state_num <= STATE_SIZE */
state_index += num;
if (state_index >= STATE_SIZE) {
state_index %= STATE_SIZE;
state_num = STATE_SIZE;
} else if (state_num < STATE_SIZE) {
if (state_index > state_num)
state_num = state_index;
}
/* state_index <= state_num <= STATE_SIZE */
/*
* state[st_idx], ..., state[(st_idx + num - 1) % STATE_SIZE] are what we
* will use now, but other threads may use them as well
*/
md_count[1] += (num / MD_DIGEST_LENGTH) + (num % MD_DIGEST_LENGTH > 0);
if (!do_not_lock)
CRYPTO_THREAD_unlock(rand_lock);
for (i = 0; i < num; i += MD_DIGEST_LENGTH) {
j = (num - i);
j = (j > MD_DIGEST_LENGTH) ? MD_DIGEST_LENGTH : j;
if (!MD_Init(m))
goto err;
if (!MD_Update(m, local_md, MD_DIGEST_LENGTH))
goto err;
k = (st_idx + j) - STATE_SIZE;
if (k > 0) {
if (!MD_Update(m, &(state[st_idx]), j - k))
goto err;
if (!MD_Update(m, &(state[0]), k))
goto err;
} else if (!MD_Update(m, &(state[st_idx]), j))
goto err;
/* DO NOT REMOVE THE FOLLOWING CALL TO MD_Update()! */
if (!MD_Update(m, buf, j))
goto err;
/*
* We know that line may cause programs such as purify and valgrind
|