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/*
* Non-physical true random number generator based on timing jitter.
*
* Copyright Stephan Mueller <smueller@chronox.de>, 2013
*
* License
* =======
*
* 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, and the entire permission notice in its entirety,
* including the disclaimer of warranties.
* 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. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* ALTERNATIVELY, this product may be distributed under the terms of
* the GNU General Public License, in which case the provisions of the GPL are
* required INSTEAD OF the above restrictions. (This clause is
* necessary due to a potential bad interaction between the GPL and
* the restrictions contained in a BSD-style copyright.)
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
* WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR 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 NOT ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*/
#ifndef GCRYPT_JITTERENTROPY_BASE_USER_H
#define GCRYPT_JITTERENTROPY_BASE_USER_H
/*
* This is Libgcrypt specific platform dependent code. We use a
* separate file because jitterentropy.h expects such a file.
*/
#ifndef USE_JENT
# error This file expects to be included from rndjent.c (via jitterentropy.h)
#endif
#ifndef HAVE_STDINT_H
# error This module needs stdint.h - try ./configure --disable-jent-support
#endif
/* When using the libgcrypt secure memory mechanism, all precautions
* are taken to protect our state. If the user disables secmem during
* runtime, it is his decision and we thus try not to overrule his
* decision for less memory protection. */
#define JENT_CPU_JITTERENTROPY_SECURE_MEMORY 1
#define jent_zalloc(n) _gcry_calloc_secure (1, (n))
static void
jent_get_nstime(u64 *out)
{
#if USE_JENT == JENT_USES_RDTSC
u32 t_eax, t_edx;
asm volatile (".byte 0x0f,0x31\n\t"
: "=a" (t_eax), "=d" (t_edx)
);
*out = (((u64)t_edx << 32) | t_eax);
#elif USE_JENT == JENT_USES_GETTIME
struct timespec tv;
u64 tmp;
/* On Linux we could use CLOCK_MONOTONIC(_RAW), but with
* CLOCK_REALTIME we get some nice extra entropy once in a while
* from the NTP actions that we want to use as well... though, we do
* not rely on that extra little entropy. */
if (!clock_gettime (CLOCK_REALTIME, &tv))
{
tmp = tv.tv_sec;
tmp = tmp << 32;
tmp = tmp | tv.tv_nsec;
}
else
tmp = 0;
*out = tmp;
#elif USE_JENT == JENT_USES_READ_REAL_TIME
/* clock_gettime() on AIX returns a timer value that increments in
* steps of 1000. */
u64 tmp = 0;
timebasestruct_t aixtime;
read_real_time (&aixtime, TIMEBASE_SZ);
tmp = aixtime.tb_high;
tmp = tmp << 32;
tmp = tmp | aixtime.tb_low;
*out = tmp;
#else
# error No clock available in jent_get_nstime
#endif
}
static GPGRT_INLINE void
jent_zfree (void *ptr, unsigned int len)
{
if (ptr)
{
wipememory (ptr, len);
_gcry_free (ptr);
}
}
static GPGRT_INLINE int
jent_fips_enabled(void)
{
return fips_mode();
}
#endif /* GCRYPT_JITTERENTROPY_BASE_USER_H */