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openssl/crypto/rand/md_rand.c
Matt Caswell 625146d9fb Fix async deadlock problem 
The rand code can aquire locks and then attempt crypto operations. This
can end up in a deadlock if we are using an async engine, because control
returns back to the user code whilst still holding the lock. We need to
force synchronous operation for these sections of code.

Reviewed-by: Rich Salz <rsalz@openssl.org>
2015-11-20 23:37:17 +00:00

752 lines
24 KiB
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/* crypto/rand/md_rand.c */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young (eay@cryptsoft.com).
* The implementation was written so as to conform with Netscapes SSL.
*
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to. The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson (tjh@cryptsoft.com).
*
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* "This product includes cryptographic software written by
* Eric Young (eay@cryptsoft.com)"
* The word 'cryptographic' can be left out if the rouines from the library
* being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from
* the apps directory (application code) you must include an acknowledgement:
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
*
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed. i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.]
*/
/* ====================================================================
* Copyright (c) 1998-2001 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* openssl-core@openssl.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com).
*
*/
#ifdef MD_RAND_DEBUG
# ifndef NDEBUG
# define NDEBUG
# endif
#endif
#include <assert.h>
#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/crypto.h>
#include <openssl/rand.h>
#include <openssl/async.h>
#include "rand_lcl.h"
#include <openssl/err.h>
#ifdef OPENSSL_FIPS
# include <openssl/fips.h>
#endif
#ifdef BN_DEBUG
# define PREDICT
#endif
/* #define PREDICT 1 */
#define STATE_SIZE 1023
static int 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 unsigned int crypto_lock_rand = 0; /* may be set only when a thread
* holds CRYPTO_LOCK_RAND (to
* prevent double locking) */
/* access to lockin_thread is synchronized by CRYPTO_LOCK_RAND2 */
/* valid iff crypto_lock_rand is set */
static CRYPTO_THREADID locking_threadid;
#ifdef PREDICT
int rand_predictable = 0;
#endif
static void 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);
#ifndef OPENSSL_NO_DEPRECATED
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,
#ifndef OPENSSL_NO_DEPRECATED
rand_pseudo_bytes,
#else
NULL,
#endif
rand_status
};
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;
}
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;
/*
* (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.
*/
EVP_MD_CTX_init(&m);
/* check if we already have the lock */
if (crypto_lock_rand) {
CRYPTO_THREADID cur;
CRYPTO_THREADID_current(&cur);
CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
do_not_lock = !CRYPTO_THREADID_cmp(&locking_threadid, &cur);
CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
} else
do_not_lock = 0;
if (!do_not_lock)
CRYPTO_w_lock(CRYPTO_LOCK_RAND);
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_w_unlock(CRYPTO_LOCK_RAND);
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
* to complain about use of uninitialized data. The problem is not,
* it's with the caller. Removing that line will make sure you get
* really bad randomness and thereby other problems such as very
* insecure keys.
*/
if (!MD_Update(&m, (unsigned char *)&(md_c[0]), sizeof(md_c)))
goto err;
if (!MD_Final(&m, local_md))
goto err;
md_c[1]++;
buf = (const char *)buf + j;
for (k = 0; k < j; k++) {
/*
* Parallel threads may interfere with this, but always each byte
* of the new state is the XOR of some previous value of its and
* local_md (itermediate values may be lost). Alway using locking
* could hurt performance more than necessary given that
* conflicts occur only when the total seeding is longer than the
* random state.
*/
state[st_idx++] ^= local_md[k];
if (st_idx >= STATE_SIZE)
st_idx = 0;
}
}
if (!do_not_lock)
CRYPTO_w_lock(CRYPTO_LOCK_RAND);
/*
* Don't just copy back local_md into md -- this could mean that other
* thread's seeding remains without effect (except for the incremented
* counter). By XORing it we keep at least as much entropy as fits into
* md.
*/
for (k = 0; k < (int)sizeof(md); k++) {
md[k] ^= local_md[k];
}
if (entropy < ENTROPY_NEEDED) /* stop counting when we have enough */
entropy += add;
if (!do_not_lock)
CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
#if !defined(OPENSSL_THREADS) && !defined(OPENSSL_SYS_WIN32)
assert(md_c[1] == md_count[1]);
#endif
rv = 1;
err:
EVP_MD_CTX_cleanup(&m);
return rv;
}
static int rand_seed(const void *buf, int num)
{
return rand_add(buf, num, (double)num);
}
static int rand_bytes(unsigned char *buf, int num, int pseudo)
{
static volatile int stirred_pool = 0;
int i, j, k, st_num, st_idx;
int num_ceil;
int ok;
long md_c[2];
unsigned char local_md[MD_DIGEST_LENGTH];
EVP_MD_CTX m;
#ifndef GETPID_IS_MEANINGLESS
pid_t curr_pid = getpid();
#endif
time_t curr_time = time(NULL);
int do_stir_pool = 0;
/* time value for various platforms */
#ifdef OPENSSL_SYS_WIN32
FILETIME tv;
# ifdef _WIN32_WCE
SYSTEMTIME t;
GetSystemTime(&t);
SystemTimeToFileTime(&t, &tv);
# else
GetSystemTimeAsFileTime(&tv);
# endif
#elif defined(OPENSSL_SYS_VXWORKS)
struct timespec tv;
clock_gettime(CLOCK_REALTIME, &ts);
#elif defined(OPENSSL_SYS_DSPBIOS)
unsigned long long tv, OPENSSL_rdtsc();
tv = OPENSSL_rdtsc();
#else
struct timeval tv;
gettimeofday(&tv, NULL);
#endif
#ifdef PREDICT
if (rand_predictable) {
static unsigned char val = 0;
for (i = 0; i < num; i++)
buf[i] = val++;
return (1);
}
#endif
if (num <= 0)
return 1;
EVP_MD_CTX_init(&m);
/* round upwards to multiple of MD_DIGEST_LENGTH/2 */
num_ceil =
(1 + (num - 1) / (MD_DIGEST_LENGTH / 2)) * (MD_DIGEST_LENGTH / 2);
/*
* (Based on the rand(3) manpage:)
*
* For each group of 10 bytes (or less), we do the following:
*
* Input into the hash function the local 'md' (which is initialized from
* the global 'md' before any bytes are generated), the bytes that are to
* be overwritten by the random bytes, and bytes from the 'state'
* (incrementing looping index). From this digest output (which is kept
* in 'md'), the top (up to) 10 bytes are returned to the caller and the
* bottom 10 bytes are xored into the 'state'.
*
* Finally, after we have finished 'num' random bytes for the
* caller, 'count' (which is incremented) and the local and global 'md'
* are fed into the hash function and the results are kept in the
* global 'md'.
*/
CRYPTO_w_lock(CRYPTO_LOCK_RAND);
/*
* We could end up in an async engine while holding this lock so ensure
* we don't pause and cause a deadlock
*/
ASYNC_block_pause();
/* prevent rand_bytes() from trying to obtain the lock again */
CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
CRYPTO_THREADID_current(&locking_threadid);
CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
crypto_lock_rand = 1;
if (!initialized) {
RAND_poll();
initialized = 1;
}
if (!stirred_pool)
do_stir_pool = 1;
ok = (entropy >= ENTROPY_NEEDED);
if (!ok) {
/*
* If the PRNG state is not yet unpredictable, then seeing the PRNG
* output may help attackers to determine the new state; thus we have
* to decrease the entropy estimate. Once we've had enough initial
* seeding we don't bother to adjust the entropy count, though,
* because we're not ambitious to provide *information-theoretic*
* randomness. NOTE: This approach fails if the program forks before
* we have enough entropy. Entropy should be collected in a separate
* input pool and be transferred to the output pool only when the
* entropy limit has been reached.
*/
entropy -= num;
if (entropy < 0)
entropy = 0;
}
if (do_stir_pool) {
/*
* In the output function only half of 'md' remains secret, so we
* better make sure that the required entropy gets 'evenly
* distributed' through 'state', our randomness pool. The input
* function (rand_add) chains all of 'md', which makes it more
* suitable for this purpose.
*/
int n = STATE_SIZE; /* so that the complete pool gets accessed */
while (n > 0) {
#if MD_DIGEST_LENGTH > 20
# error "Please adjust DUMMY_SEED."
#endif
#define DUMMY_SEED "...................." /* at least MD_DIGEST_LENGTH */
/*
* Note that the seed does not matter, it's just that
* rand_add expects to have something to hash.
*/
rand_add(DUMMY_SEED, MD_DIGEST_LENGTH, 0.0);
n -= MD_DIGEST_LENGTH;
}
if (ok)
stirred_pool = 1;
}
st_idx = state_index;
st_num = state_num;
md_c[0] = md_count[0];
md_c[1] = md_count[1];
memcpy(local_md, md, sizeof md);
state_index += num_ceil;
if (state_index > state_num)
state_index %= state_num;
/*
* state[st_idx], ..., state[(st_idx + num_ceil - 1) % st_num] are now
* ours (but other threads may use them too)
*/
md_count[0] += 1;
/* before unlocking, we must clear 'crypto_lock_rand' */
crypto_lock_rand = 0;
ASYNC_unblock_pause();
CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
while (num > 0) {
/* num_ceil -= MD_DIGEST_LENGTH/2 */
j = (num >= MD_DIGEST_LENGTH / 2) ? MD_DIGEST_LENGTH / 2 : num;
num -= j;
if (!MD_Init(&m))
goto err;
#ifndef GETPID_IS_MEANINGLESS
if (curr_pid) { /* just in the first iteration to save time */
if (!MD_Update(&m, (unsigned char *)&curr_pid, sizeof curr_pid))
goto err;
curr_pid = 0;
}
#endif
if (curr_time) { /* just in the first iteration to save time */
if (!MD_Update(&m, (unsigned char *)&curr_time, sizeof curr_time))
goto err;
if (!MD_Update(&m, (unsigned char *)&tv, sizeof tv))
goto err;
curr_time = 0;
rand_hw_seed(&m);
}
if (!MD_Update(&m, local_md, MD_DIGEST_LENGTH))
goto err;
if (!MD_Update(&m, (unsigned char *)&(md_c[0]), sizeof(md_c)))
goto err;
#ifndef PURIFY /* purify complains */
/*
* The following line uses the supplied buffer as a small source of
* entropy: since this buffer is often uninitialised it may cause
* programs such as purify or valgrind to complain. So for those
* builds it is not used: the removal of such a small source of
* entropy has negligible impact on security.
*/
if (!MD_Update(&m, buf, j))
goto err;
#endif
k = (st_idx + MD_DIGEST_LENGTH / 2) - st_num;
if (k > 0) {
if (!MD_Update(&m, &(state[st_idx]), MD_DIGEST_LENGTH / 2 - k))
goto err;
if (!MD_Update(&m, &(state[0]), k))
goto err;
} else if (!MD_Update(&m, &(state[st_idx]), MD_DIGEST_LENGTH / 2))
goto err;
if (!MD_Final(&m, local_md))
goto err;
for (i = 0; i < MD_DIGEST_LENGTH / 2; i++) {
/* may compete with other threads */
state[st_idx++] ^= local_md[i];
if (st_idx >= st_num)
st_idx = 0;
if (i < j)
*(buf++) = local_md[i + MD_DIGEST_LENGTH / 2];
}
}
if (!MD_Init(&m)
|| !MD_Update(&m, (unsigned char *)&(md_c[0]), sizeof(md_c))
|| !MD_Update(&m, local_md, MD_DIGEST_LENGTH))
goto err;
CRYPTO_w_lock(CRYPTO_LOCK_RAND);
/*
* Prevent deadlocks if we end up in an async engine
*/
ASYNC_block_pause();
if (!MD_Update(&m, md, MD_DIGEST_LENGTH) || !MD_Final(&m, md)) {
CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
goto err;
}
ASYNC_unblock_pause();
CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
EVP_MD_CTX_cleanup(&m);
if (ok)
return (1);
else if (pseudo)
return 0;
else {
RANDerr(RAND_F_RAND_BYTES, RAND_R_PRNG_NOT_SEEDED);
ERR_add_error_data(1, "You need to read the OpenSSL FAQ, "
"http://www.openssl.org/support/faq.html");
return (0);
}
err:
EVP_MD_CTX_cleanup(&m);
RANDerr(RAND_F_RAND_BYTES, ERR_R_EVP_LIB);
return 0;
}
static int rand_nopseudo_bytes(unsigned char *buf, int num)
{
return rand_bytes(buf, num, 0);
}
#ifndef OPENSSL_NO_DEPRECATED
/*
* pseudo-random bytes that are guaranteed to be unique but not unpredictable
*/
static int rand_pseudo_bytes(unsigned char *buf, int num)
{
return rand_bytes(buf, num, 1);
}
#endif
static int rand_status(void)
{
CRYPTO_THREADID cur;
int ret;
int do_not_lock;
CRYPTO_THREADID_current(&cur);
/*
* check if we already have the lock (could happen if a RAND_poll()
* implementation calls RAND_status())
*/
if (crypto_lock_rand) {
CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
do_not_lock = !CRYPTO_THREADID_cmp(&locking_threadid, &cur);
CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
} else
do_not_lock = 0;
if (!do_not_lock) {
CRYPTO_w_lock(CRYPTO_LOCK_RAND);
/*
* Prevent deadlocks in case we end up in an async engine
*/
ASYNC_block_pause();
/*
* prevent rand_bytes() from trying to obtain the lock again
*/
CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
CRYPTO_THREADID_cpy(&locking_threadid, &cur);
CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
crypto_lock_rand = 1;
}
if (!initialized) {
RAND_poll();
initialized = 1;
}
ret = entropy >= ENTROPY_NEEDED;
if (!do_not_lock) {
/* before unlocking, we must clear 'crypto_lock_rand' */
crypto_lock_rand = 0;
ASYNC_unblock_pause();
CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
}
return ret;
}
/*
* rand_hw_seed: get seed data from any available hardware RNG. only
* currently supports rdrand.
*/
/* Adapted from eng_rdrand.c */
#if (defined(__i386) || defined(__i386__) || defined(_M_IX86) || \
defined(__x86_64) || defined(__x86_64__) || \
defined(_M_AMD64) || defined (_M_X64)) && defined(OPENSSL_CPUID_OBJ)
# define RDRAND_CALLS 4
size_t OPENSSL_ia32_rdrand(void);
extern unsigned int OPENSSL_ia32cap_P[];
static void rand_hw_seed(EVP_MD_CTX *ctx)
{
int i;
if (!(OPENSSL_ia32cap_P[1] & (1 << (62 - 32))))
return;
for (i = 0; i < RDRAND_CALLS; i++) {
size_t rnd;
rnd = OPENSSL_ia32_rdrand();
if (rnd == 0)
return;
MD_Update(ctx, (unsigned char *)&rnd, sizeof(size_t));
}
}
/* XOR an existing buffer with random data */
void rand_hw_xor(unsigned char *buf, size_t num)
{
size_t rnd;
if (!(OPENSSL_ia32cap_P[1] & (1 << (62 - 32))))
return;
while (num >= sizeof(size_t)) {
rnd = OPENSSL_ia32_rdrand();
if (rnd == 0)
return;
*((size_t *)buf) ^= rnd;
buf += sizeof(size_t);
num -= sizeof(size_t);
}
if (num) {
rnd = OPENSSL_ia32_rdrand();
if (rnd == 0)
return;
while (num) {
*buf ^= rnd & 0xff;
rnd >>= 8;
buf++;
num--;
}
}
}
#else
static void rand_hw_seed(EVP_MD_CTX *ctx)
{
return;
}
void rand_hw_xor(unsigned char *buf, size_t num)
{
return;
}
#endif
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