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f3c8355c7a
If neither gcrypt or gnutls are available to provide a cryptographic random number generator, fallback to consuming bytes directly from /dev/[u]random. Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
65 lines
1.8 KiB
C
65 lines
1.8 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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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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int fd;
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int ret = -1;
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int got;
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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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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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close(fd);
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return ret;
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}
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