blob: 92eed0ee78296d4e0e612511f5b060c3eaef47bc [file] [log] [blame]
Daniel P. Berrangef3c83552016-07-21 10:37:14 +01001/*
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
Geert Martin Ijewskia3727812017-04-26 00:15:01 +020025#ifdef _WIN32
Gerd Hoffmann612fc052017-05-16 07:24:39 +020026#include <wincrypt.h>
Geert Martin Ijewskia3727812017-04-26 00:15:01 +020027static HCRYPTPROV hCryptProv;
28#else
29static int fd; /* a file handle to either /dev/urandom or /dev/random */
30#endif
Daniel P. Berrangef3c83552016-07-21 10:37:14 +010031
Geert Martin Ijewskia3727812017-04-26 00:15:01 +020032int qcrypto_random_init(Error **errp)
33{
34#ifndef _WIN32
Daniel P. Berrangef3c83552016-07-21 10:37:14 +010035 /* 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 }
Geert Martin Ijewskia3727812017-04-26 00:15:01 +020046#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;
Daniel P. Berrangef3c83552016-07-21 10:37:14 +010065
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:
Daniel P. Berrangef3c83552016-07-21 10:37:14 +010083 return ret;
Geert Martin Ijewskia3727812017-04-26 00:15:01 +020084#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
Daniel P. Berrangef3c83552016-07-21 10:37:14 +010093}