e9979ca64e
Avoids leaking the /dev/urandom fd into any child processes. Reviewed-by: Laurent Vivier <lvivier@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
88 lines
2.5 KiB
C
88 lines
2.5 KiB
C
/*
|
|
* 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 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
|
|
static int fd; /* a file handle to either /dev/urandom or /dev/random */
|
|
#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
|
|
/* TBD perhaps also add support for BSD getentropy / Linux
|
|
* getrandom syscalls directly */
|
|
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(errp, "No /dev/urandom or /dev/random found");
|
|
return -1;
|
|
}
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
int qcrypto_random_bytes(uint8_t *buf G_GNUC_UNUSED,
|
|
size_t buflen G_GNUC_UNUSED,
|
|
Error **errp)
|
|
{
|
|
#ifdef _WIN32
|
|
if (!CryptGenRandom(hCryptProv, buflen, buf)) {
|
|
error_setg_win32(errp, GetLastError(),
|
|
"Unable to read random bytes");
|
|
return -1;
|
|
}
|
|
#else
|
|
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;
|
|
}
|