LXR qemu/crypto/random-platform.c

   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 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
  30static int fd; /* a file handle to either /dev/urandom or /dev/random */
  31#endif
  32
  33int qcrypto_random_init(Error **errp)
  34{
  35#ifndef _WIN32
  36    /* TBD perhaps also add support for BSD getentropy / Linux
  37     * getrandom syscalls directly */
  38    fd = open("/dev/urandom", O_RDONLY);
  39    if (fd == -1 && errno == ENOENT) {
  40        fd = open("/dev/random", O_RDONLY);
  41    }
  42
  43    if (fd < 0) {
  44        error_setg(errp, "No /dev/urandom or /dev/random found");
  45        return -1;
  46    }
  47#else
  48    if (!CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_FULL,
  49                             CRYPT_SILENT | CRYPT_VERIFYCONTEXT)) {
  50        error_setg_win32(errp, GetLastError(),
  51                         "Unable to create cryptographic provider");
  52        return -1;
  53    }
  54#endif
  55
  56    return 0;
  57}
  58
  59int qcrypto_random_bytes(uint8_t *buf G_GNUC_UNUSED,
  60                         size_t buflen G_GNUC_UNUSED,
  61                         Error **errp)
  62{
  63#ifndef _WIN32
  64    int ret = -1;
  65    int got;
  66
  67    while (buflen > 0) {
  68        got = read(fd, buf, buflen);
  69        if (got < 0) {
  70            error_setg_errno(errp, errno,
  71                             "Unable to read random bytes");
  72            goto cleanup;
  73        } else if (!got) {
  74            error_setg(errp,
  75                       "Unexpected EOF reading random bytes");
  76            goto cleanup;
  77        }
  78        buflen -= got;
  79        buf += got;
  80    }
  81
  82    ret = 0;
  83 cleanup:
  84    return ret;
  85#else
  86    if (!CryptGenRandom(hCryptProv, buflen, buf)) {
  87        error_setg_win32(errp, GetLastError(),
  88                         "Unable to read random bytes");
  89        return -1;
  90    }
  91
  92    return 0;
  93#endif
  94}
  95