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 int 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