db1ed1abcf
Prefer it to direct use of /dev/urandom. Reviewed-by: Laurent Vivier <lvivier@redhat.com> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
115 lines
3.2 KiB
C
115 lines
3.2 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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#include "qapi/error.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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# ifdef CONFIG_GETRANDOM
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# include <sys/random.h>
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# endif
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/* This is -1 for getrandom(), or a file handle for /dev/{u,}random. */
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static int fd;
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#endif
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int qcrypto_random_init(Error **errp)
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{
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#ifdef _WIN32
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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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#else
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# ifdef CONFIG_GETRANDOM
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if (getrandom(NULL, 0, 0) == 0) {
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/* Use getrandom() */
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fd = -1;
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return 0;
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}
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/* Fall through to /dev/urandom case. */
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# endif
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fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC);
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if (fd == -1 && errno == ENOENT) {
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fd = open("/dev/random", O_RDONLY | O_CLOEXEC);
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}
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if (fd < 0) {
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error_setg_errno(errp, errno, "No /dev/urandom or /dev/random");
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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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#ifdef _WIN32
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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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#else
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# ifdef CONFIG_GETRANDOM
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if (likely(fd < 0)) {
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while (1) {
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ssize_t got = getrandom(buf, buflen, 0);
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if (likely(got == buflen)) {
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return 0;
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}
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if (got >= 0) {
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buflen -= got;
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buf += got;
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} else if (errno != EINTR) {
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error_setg_errno(errp, errno, "getrandom");
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return -1;
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}
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}
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}
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/* Fall through to /dev/urandom case. */
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# endif
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while (1) {
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ssize_t got = read(fd, buf, buflen);
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if (likely(got == buflen)) {
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return 0;
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}
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if (got > 0) {
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buflen -= got;
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buf += got;
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} else if (got == 0) {
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error_setg(errp, "Unexpected EOF reading random bytes");
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return -1;
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} else if (errno != EINTR) {
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error_setg_errno(errp, errno, "Unable to read random bytes");
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return -1;
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}
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}
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#endif
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return 0;
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}
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