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