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/* hwfeatures.c - Detect hardware features.
* Copyright (C) 2007, 2011 Free Software Foundation, Inc.
* Copyright (C) 2012 g10 Code GmbH
*
* This file is part of Libgcrypt.
*
* Libgcrypt is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* Libgcrypt is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>
#ifdef HAVE_SYSLOG
# include <syslog.h>
#endif /*HAVE_SYSLOG*/
#include "g10lib.h"
#include "hwf-common.h"
/* The name of a file used to globally disable selected features. */
#define HWF_DENY_FILE "/etc/gcrypt/hwf.deny"
/* A table to map hardware features to a string. */
static struct
{
unsigned int flag;
const char *desc;
} hwflist[] =
{
{ HWF_PADLOCK_RNG, "padlock-rng" },
{ HWF_PADLOCK_AES, "padlock-aes" },
{ HWF_PADLOCK_SHA, "padlock-sha" },
{ HWF_PADLOCK_MMUL, "padlock-mmul"},
{ HWF_INTEL_CPU, "intel-cpu" },
{ HWF_INTEL_FAST_SHLD, "intel-fast-shld" },
{ HWF_INTEL_BMI2, "intel-bmi2" },
{ HWF_INTEL_SSSE3, "intel-ssse3" },
{ HWF_INTEL_SSE4_1, "intel-sse4.1" },
{ HWF_INTEL_PCLMUL, "intel-pclmul" },
{ HWF_INTEL_AESNI, "intel-aesni" },
{ HWF_INTEL_RDRAND, "intel-rdrand" },
{ HWF_INTEL_AVX, "intel-avx" },
{ HWF_INTEL_AVX2, "intel-avx2" },
{ HWF_ARM_NEON, "arm-neon" },
{ HWF_ARM_AES, "arm-aes" },
{ HWF_ARM_SHA1, "arm-sha1" },
{ HWF_ARM_SHA2, "arm-sha2" },
{ HWF_ARM_PMULL, "arm-pmull" }
};
/* A bit vector with the hardware features which shall not be used.
This variable must be set prior to any initialization. */
static unsigned int disabled_hw_features;
/* A bit vector describing the hardware features currently
available. */
static unsigned int hw_features;
/* Convenience macros. */
#define my_isascii(c) (!((c) & 0x80))
/* Disable a feature by name. This function must be called *before*
_gcry_detect_hw_features is called. */
gpg_err_code_t
_gcry_disable_hw_feature (const char *name)
{
int i;
if (!strcmp(name, "all"))
{
disabled_hw_features = ~0;
return 0;
}
for (i=0; i < DIM (hwflist); i++)
if (!strcmp (hwflist[i].desc, name))
{
disabled_hw_features |= hwflist[i].flag;
return 0;
}
return GPG_ERR_INV_NAME;
}
/* Return a bit vector describing the available hardware features.
The HWF_ constants are used to test for them. */
unsigned int
_gcry_get_hw_features (void)
{
return hw_features;
}
/* Enumerate all features. The caller is expected to start with an
IDX of 0 and then increment IDX until NULL is returned. */
const char *
_gcry_enum_hw_features (int idx, unsigned int *r_feature)
{
if (idx < 0 || idx >= DIM (hwflist))
return NULL;
if (r_feature)
*r_feature = hwflist[idx].flag;
return hwflist[idx].desc;
}
/* Read a file with features which shall not be used. The file is a
simple text file where empty lines and lines with the first non
white-space character being '#' are ignored. */
static void
parse_hwf_deny_file (void)
{
const char *fname = HWF_DENY_FILE;
FILE *fp;
char buffer[256];
char *p, *pend;
int i, lnr = 0;
fp = fopen (fname, "r");
if (!fp)
return;
for (;;)
{
if (!fgets (buffer, sizeof buffer, fp))
{
if (!feof (fp))
{
#ifdef HAVE_SYSLOG
syslog (LOG_USER|LOG_WARNING,
"Libgcrypt warning: error reading '%s', line %d",
fname, lnr);
#endif /*HAVE_SYSLOG*/
}
fclose (fp);
return;
}
lnr++;
for (p=buffer; my_isascii (*p) && isspace (*p); p++)
;
pend = strchr (p, '\n');
if (pend)
*pend = 0;
pend = p + (*p? (strlen (p)-1):0);
for ( ;pend > p; pend--)
if (my_isascii (*pend) && isspace (*pend))
*pend = 0;
if (!*p || *p == '#')
continue;
if (_gcry_disable_hw_feature (p) == GPG_ERR_INV_NAME)
{
#ifdef HAVE_SYSLOG
syslog (LOG_USER|LOG_WARNING,
"Libgcrypt warning: unknown feature in '%s', line %d",
fname, lnr);
#endif /*HAVE_SYSLOG*/
}
}
}
/* Detect the available hardware features. This function is called
once right at startup and we assume that no other threads are
running. */
void
_gcry_detect_hw_features (void)
{
hw_features = 0;
if (fips_mode ())
return; /* Hardware support is not to be evaluated. */
parse_hwf_deny_file ();
#if defined (HAVE_CPU_ARCH_X86)
{
hw_features = _gcry_hwf_detect_x86 ();
}
#endif /* HAVE_CPU_ARCH_X86 */
#if defined (HAVE_CPU_ARCH_ARM)
{
hw_features = _gcry_hwf_detect_arm ();
}
#endif /* HAVE_CPU_ARCH_ARM */
hw_features &= ~disabled_hw_features;
}

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Sun, Jan 25, 9:43 PM (1 d, 13 h)
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