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/*
* QEMU Crypto random number provider
*
* Copyright (c) 2015-2016 Red Hat, Inc.
*
* This library 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.
*
* This library 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 library; if not, see <http://www.gnu.org/licenses/>.
*
*/
#include "qemu/osdep.h"
#include "crypto/random.h"
#include "qapi/error.h"
#ifdef _WIN32
#include <wincrypt.h>
static HCRYPTPROV hCryptProv;
#else
# ifdef CONFIG_GETRANDOM
# include <sys/random.h>
# endif
/* This is -1 for getrandom(), or a file handle for /dev/{u,}random. */
static int fd;
#endif
int qcrypto_random_init(Error **errp)
{
#ifdef _WIN32
if (!CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_FULL,
CRYPT_SILENT | CRYPT_VERIFYCONTEXT)) {
error_setg_win32(errp, GetLastError(),
"Unable to create cryptographic provider");
return -1;
}
#else
# ifdef CONFIG_GETRANDOM
if (getrandom(NULL, 0, 0) == 0) {
/* Use getrandom() */
fd = -1;
return 0;
}
/* Fall through to /dev/urandom case. */
# endif
fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC);
if (fd == -1 && errno == ENOENT) {
fd = open("/dev/random", O_RDONLY | O_CLOEXEC);
}
if (fd < 0) {
error_setg_errno(errp, errno, "No /dev/urandom or /dev/random");
return -1;
}
#endif
return 0;
}
int qcrypto_random_bytes(void *buf,
size_t buflen,
Error **errp)
{
#ifdef _WIN32
if (!CryptGenRandom(hCryptProv, buflen, buf)) {
error_setg_win32(errp, GetLastError(),
"Unable to read random bytes");
return -1;
}
#else
# ifdef CONFIG_GETRANDOM
if (likely(fd < 0)) {
while (1) {
ssize_t got = getrandom(buf, buflen, 0);
if (likely(got == buflen)) {
return 0;
}
if (got >= 0) {
buflen -= got;
buf += got;
} else if (errno != EINTR) {
error_setg_errno(errp, errno, "getrandom");
return -1;
}
}
}
/* Fall through to /dev/urandom case. */
# endif
while (1) {
ssize_t got = read(fd, buf, buflen);
if (likely(got == buflen)) {
return 0;
}
if (got > 0) {
buflen -= got;
buf += got;
} else if (got == 0) {
error_setg(errp, "Unexpected EOF reading random bytes");
return -1;
} else if (errno != EINTR) {
error_setg_errno(errp, errno, "Unable to read random bytes");
return -1;
}
}
#endif
return 0;
}
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