a37278169d
If no crypto library is included in the build, QEMU uses qcrypto_random_bytes() to generate random data. That function tried to open /dev/urandom or /dev/random and if opening both files failed it errored out. Those files obviously do not exist on windows, so there the code uses CryptGenRandom(). Furthermore there was some refactoring and a new function qcrypto_random_init() was introduced. If a proper crypto library (gnutls or libgcrypt) is included in the build, this function does nothing. If neither is included it initializes the (platform specific) handles that are used by qcrypto_random_bytes(). Either: * a handle to /dev/urandom | /dev/random on unix like systems * a handle to a cryptographic service provider on windows Signed-off-by: Geert Martin Ijewski <gm.ijewski@web.de> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
94 lines
2.5 KiB
C
94 lines
2.5 KiB
C
/*
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* QEMU Crypto random number provider
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*
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* Copyright (c) 2015-2016 Red Hat, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include "qemu/osdep.h"
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#include "crypto/random.h"
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#ifdef _WIN32
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#include <Wincrypt.h>
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static HCRYPTPROV hCryptProv;
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#else
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static int fd; /* a file handle to either /dev/urandom or /dev/random */
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#endif
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int qcrypto_random_init(Error **errp)
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{
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#ifndef _WIN32
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/* TBD perhaps also add support for BSD getentropy / Linux
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* getrandom syscalls directly */
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fd = open("/dev/urandom", O_RDONLY);
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if (fd == -1 && errno == ENOENT) {
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fd = open("/dev/random", O_RDONLY);
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}
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if (fd < 0) {
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error_setg(errp, "No /dev/urandom or /dev/random found");
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return -1;
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}
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#else
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if (!CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_FULL,
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CRYPT_SILENT | CRYPT_VERIFYCONTEXT)) {
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error_setg_win32(errp, GetLastError(),
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"Unable to create cryptographic provider");
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return -1;
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}
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#endif
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return 0;
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}
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int qcrypto_random_bytes(uint8_t *buf G_GNUC_UNUSED,
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size_t buflen G_GNUC_UNUSED,
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Error **errp)
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{
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#ifndef _WIN32
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int ret = -1;
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int got;
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while (buflen > 0) {
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got = read(fd, buf, buflen);
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if (got < 0) {
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error_setg_errno(errp, errno,
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"Unable to read random bytes");
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goto cleanup;
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} else if (!got) {
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error_setg(errp,
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"Unexpected EOF reading random bytes");
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goto cleanup;
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}
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buflen -= got;
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buf += got;
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}
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ret = 0;
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cleanup:
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return ret;
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#else
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if (!CryptGenRandom(hCryptProv, buflen, buf)) {
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error_setg_win32(errp, GetLastError(),
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"Unable to read random bytes");
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return -1;
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}
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return 0;
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#endif
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}
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