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
  25int qcrypto_random_bytes(uint8_t *buf G_GNUC_UNUSED,
  26                         size_t buflen G_GNUC_UNUSED,
  27                         Error **errp)
  28{
  29    int fd;
  30    int ret = -1;
  31    int got;
  32
  33    /* TBD perhaps also add support for BSD getentropy / Linux
  34     * getrandom syscalls directly */
  35    fd = open("/dev/urandom", O_RDONLY);
  36    if (fd == -1 && errno == ENOENT) {
  37        fd = open("/dev/random", O_RDONLY);
  38    }
  39
  40    if (fd < 0) {
  41        error_setg(errp, "No /dev/urandom or /dev/random found");
  42        return -1;
  43    }
  44
  45    while (buflen > 0) {
  46        got = read(fd, buf, buflen);
  47        if (got < 0) {
  48            error_setg_errno(errp, errno,
  49                             "Unable to read random bytes");
  50            goto cleanup;
  51        } else if (!got) {
  52            error_setg(errp,
  53                       "Unexpected EOF reading random bytes");
  54            goto cleanup;
  55        }
  56        buflen -= got;
  57        buf += got;
  58    }
  59
  60    ret = 0;
  61 cleanup:
  62    close(fd);
  63    return ret;
  64}
  65