101 lines
2.5 KiB
C
101 lines
2.5 KiB
C
/*
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* QEMU guest-visible random functions
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*
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* Copyright 2019 Linaro, Ltd.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*/
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#include "qemu/osdep.h"
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#include "qemu/cutils.h"
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#include "qapi/error.h"
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#include "qemu/guest-random.h"
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#include "crypto/random.h"
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#include "sysemu/replay.h"
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static __thread GRand *thread_rand;
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static bool deterministic;
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static int glib_random_bytes(void *buf, size_t len)
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{
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GRand *rand = thread_rand;
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size_t i;
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uint32_t x;
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if (unlikely(rand == NULL)) {
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/* Thread not initialized for a cpu, or main w/o -seed. */
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thread_rand = rand = g_rand_new();
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}
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for (i = 0; i + 4 <= len; i += 4) {
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x = g_rand_int(rand);
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__builtin_memcpy(buf + i, &x, 4);
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}
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if (i < len) {
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x = g_rand_int(rand);
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__builtin_memcpy(buf + i, &x, len - i);
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}
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return 0;
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}
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int qemu_guest_getrandom(void *buf, size_t len, Error **errp)
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{
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int ret;
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if (replay_mode == REPLAY_MODE_PLAY) {
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return replay_read_random(buf, len);
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}
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if (unlikely(deterministic)) {
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/* Deterministic implementation using Glib's Mersenne Twister. */
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ret = glib_random_bytes(buf, len);
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} else {
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/* Non-deterministic implementation using crypto routines. */
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ret = qcrypto_random_bytes(buf, len, errp);
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}
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if (replay_mode == REPLAY_MODE_RECORD) {
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replay_save_random(ret, buf, len);
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}
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return ret;
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}
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void qemu_guest_getrandom_nofail(void *buf, size_t len)
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{
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(void)qemu_guest_getrandom(buf, len, &error_fatal);
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}
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uint64_t qemu_guest_random_seed_thread_part1(void)
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{
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if (deterministic) {
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uint64_t ret;
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glib_random_bytes(&ret, sizeof(ret));
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return ret;
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}
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return 0;
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}
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void qemu_guest_random_seed_thread_part2(uint64_t seed)
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{
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g_assert(thread_rand == NULL);
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if (deterministic) {
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thread_rand =
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g_rand_new_with_seed_array((const guint32 *)&seed,
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sizeof(seed) / sizeof(guint32));
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}
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}
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int qemu_guest_random_seed_main(const char *optarg, Error **errp)
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{
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unsigned long long seed;
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if (parse_uint_full(optarg, &seed, 0)) {
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error_setg(errp, "Invalid seed number: %s", optarg);
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return -1;
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} else {
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deterministic = true;
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qemu_guest_random_seed_thread_part2(seed);
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return 0;
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}
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}
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