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
  25#ifdef _WIN32
  26#include <wincrypt.h>
  27static HCRYPTPROV hCryptProv;
  28#else
  29static int fd; /* a file handle to either /dev/urandom or /dev/random */
  30#endif
  31
  32int qcrypto_random_init(Error **errp)
  33{
  34#ifndef _WIN32
  35    /* TBD perhaps also add support for BSD getentropy / Linux
  36     * getrandom syscalls directly */
  37    fd = open("/dev/urandom", O_RDONLY);
  38    if (fd == -1 && errno == ENOENT) {
  39        fd = open("/dev/random", O_RDONLY);
  40    }
  41
  42    if (fd < 0) {
  43        error_setg(errp, "No /dev/urandom or /dev/random found");
  44        return -1;
  45    }
  46#else
  47    if (!CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_FULL,
  48                             CRYPT_SILENT | CRYPT_VERIFYCONTEXT)) {
  49        error_setg_win32(errp, GetLastError(),
  50                         "Unable to create cryptographic provider");
  51        return -1;
  52    }
  53#endif
  54
  55    return 0;
  56}
  57
  58int qcrypto_random_bytes(uint8_t *buf G_GNUC_UNUSED,
  59                         size_t buflen G_GNUC_UNUSED,
  60                         Error **errp)
  61{
  62#ifndef _WIN32
  63    int ret = -1;
  64    int got;
  65
  66    while (buflen > 0) {
  67        got = read(fd, buf, buflen);
  68        if (got < 0) {
  69            error_setg_errno(errp, errno,
  70                             "Unable to read random bytes");
  71            goto cleanup;
  72        } else if (!got) {
  73            error_setg(errp,
  74                       "Unexpected EOF reading random bytes");
  75            goto cleanup;
  76        }
  77        buflen -= got;
  78        buf += got;
  79    }
  80
  81    ret = 0;
  82 cleanup:
  83    return ret;
  84#else
  85    if (!CryptGenRandom(hCryptProv, buflen, buf)) {
  86        error_setg_win32(errp, GetLastError(),
  87                         "Unable to read random bytes");
  88        return -1;
  89    }
  90
  91    return 0;
  92#endif
  93}
  94