cachepc-qemu

Fork of AMDESE/qemu with changes for cachepc side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-qemu
Log | Files | Refs | Submodules | LICENSE | sfeed.txt

random-platform.c (3210B)

      1/*
      2 * QEMU Crypto random number provider
      3 *
      4 * Copyright (c) 2015-2016 Red Hat, Inc.
      5 *
      6 * This library is free software; you can redistribute it and/or
      7 * modify it under the terms of the GNU Lesser General Public
      8 * License as published by the Free Software Foundation; either
      9 * version 2.1 of the License, or (at your option) any later version.
     10 *
     11 * This library is distributed in the hope that it will be useful,
     12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
     13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     14 * Lesser General Public License for more details.
     15 *
     16 * You should have received a copy of the GNU Lesser General Public
     17 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
     18 *
     19 */
     20
     21#include "qemu/osdep.h"
     22
     23#include "crypto/random.h"
     24#include "qapi/error.h"
     25
     26#ifdef _WIN32
     27#include <wincrypt.h>
     28static HCRYPTPROV hCryptProv;
     29#else
     30# ifdef CONFIG_GETRANDOM
     31#  include <sys/random.h>
     32# endif
     33/* This is -1 for getrandom(), or a file handle for /dev/{u,}random.  */
     34static int fd;
     35#endif
     36
     37int qcrypto_random_init(Error **errp)
     38{
     39#ifdef _WIN32
     40    if (!CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_FULL,
     41                             CRYPT_SILENT | CRYPT_VERIFYCONTEXT)) {
     42        error_setg_win32(errp, GetLastError(),
     43                         "Unable to create cryptographic provider");
     44        return -1;
     45    }
     46#else
     47# ifdef CONFIG_GETRANDOM
     48    if (getrandom(NULL, 0, 0) == 0) {
     49        /* Use getrandom() */
     50        fd = -1;
     51        return 0;
     52    }
     53    /* Fall through to /dev/urandom case.  */
     54# endif
     55    fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC);
     56    if (fd == -1 && errno == ENOENT) {
     57        fd = open("/dev/random", O_RDONLY | O_CLOEXEC);
     58    }
     59    if (fd < 0) {
     60        error_setg_errno(errp, errno, "No /dev/urandom or /dev/random");
     61        return -1;
     62    }
     63#endif
     64    return 0;
     65}
     66
     67int qcrypto_random_bytes(void *buf,
     68                         size_t buflen,
     69                         Error **errp)
     70{
     71#ifdef _WIN32
     72    if (!CryptGenRandom(hCryptProv, buflen, buf)) {
     73        error_setg_win32(errp, GetLastError(),
     74                         "Unable to read random bytes");
     75        return -1;
     76    }
     77#else
     78# ifdef CONFIG_GETRANDOM
     79    if (likely(fd < 0)) {
     80        while (1) {
     81            ssize_t got = getrandom(buf, buflen, 0);
     82            if (likely(got == buflen)) {
     83                return 0;
     84            }
     85            if (got >= 0) {
     86                buflen -= got;
     87                buf += got;
     88            } else if (errno != EINTR) {
     89                error_setg_errno(errp, errno, "getrandom");
     90                return -1;
     91            }
     92        }
     93    }
     94    /* Fall through to /dev/urandom case.  */
     95# endif
     96    while (1) {
     97        ssize_t got = read(fd, buf, buflen);
     98        if (likely(got == buflen)) {
     99            return 0;
    100        }
    101        if (got > 0) {
    102            buflen -= got;
    103            buf += got;
    104        } else if (got == 0) {
    105            error_setg(errp, "Unexpected EOF reading random bytes");
    106            return -1;
    107        } else if (errno != EINTR) {
    108            error_setg_errno(errp, errno, "Unable to read random bytes");
    109            return -1;
    110        }
    111    }
    112#endif
    113    return 0;
    114}