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> 27 static HCRYPTPROV hCryptProv; 28 #else 29 static int fd; /* a file handle to either /dev/urandom or /dev/random */ 30 #endif 31 32 int 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 58 int 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