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/*
* Copyright (c) 2019-2022 Yubico AB. All rights reserved.
* Use of this source code is governed by a BSD-style
* license that can be found in the LICENSE file.
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <openssl/sha.h>
#include <err.h>
#include <fcntl.h>
#include <limits.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "mutator_aux.h"
extern int fuzz_save_corpus;
static bool debug;
static unsigned int flags = MUTATE_ALL;
static unsigned long long test_fail;
static unsigned long long test_total;
static unsigned long long mutate_fail;
static unsigned long long mutate_total;
int LLVMFuzzerInitialize(int *, char ***);
int LLVMFuzzerTestOneInput(const uint8_t *, size_t);
size_t LLVMFuzzerCustomMutator(uint8_t *, size_t, size_t, unsigned int);
static int
save_seed(const char *opt)
{
const char *path;
int fd = -1, status = 1;
void *buf = NULL;
const size_t buflen = MAXCORPUS;
size_t n;
struct param *p = NULL;
if ((path = strchr(opt, '=')) == NULL || strlen(++path) == 0) {
warnx("usage: --fido-save-seed=<path>");
goto fail;
}
if ((fd = open(path, O_CREAT|O_TRUNC|O_WRONLY, 0644)) == -1) {
warn("open %s", path);
goto fail;
}
if ((buf = malloc(buflen)) == NULL) {
warn("malloc");
goto fail;
}
n = pack_dummy(buf, buflen);
if ((p = unpack(buf, n)) == NULL) {
warnx("unpack");
goto fail;
}
if (write(fd, buf, n) != (ssize_t)n) {
warn("write %s", path);
goto fail;
}
status = 0;
fail:
if (fd != -1)
close(fd);
free(buf);
free(p);
return status;
}
static int
save_corpus(const struct param *p)
{
uint8_t blob[MAXCORPUS], dgst[SHA256_DIGEST_LENGTH];
size_t blob_len;
char path[PATH_MAX];
int r, fd;
if ((blob_len = pack(blob, sizeof(blob), p)) == 0 ||
blob_len > sizeof(blob)) {
warnx("pack");
return -1;
}
if (SHA256(blob, blob_len, dgst) != dgst) {
warnx("sha256");
return -1;
}
if ((r = snprintf(path, sizeof(path), "saved_corpus_%02x%02x%02x%02x"
"%02x%02x%02x%02x", dgst[0], dgst[1], dgst[2], dgst[3], dgst[4],
dgst[5], dgst[6], dgst[7])) < 0 || (size_t)r >= sizeof(path)) {
warnx("snprintf");
return -1;
}
if ((fd = open(path, O_CREAT|O_TRUNC|O_WRONLY, 0644)) == -1) {
warn("open %s", path);
return -1;
}
if (write(fd, blob, blob_len) != (ssize_t)blob_len) {
warn("write");
r = -1;
} else {
warnx("wrote %s", path);
r = 0;
}
close(fd);
return r;
}
static void
parse_mutate_flags(const char *opt, unsigned int *mutate_flags)
{
const char *f;
if ((f = strchr(opt, '=')) == NULL || strlen(++f) == 0)
errx(1, "usage: --fido-mutate=<flag>");
if (strcmp(f, "seed") == 0)
*mutate_flags |= MUTATE_SEED;
else if (strcmp(f, "param") == 0)
*mutate_flags |= MUTATE_PARAM;
else if (strcmp(f, "wiredata") == 0)
*mutate_flags |= MUTATE_WIREDATA;
else
errx(1, "--fido-mutate: unknown flag '%s'", f);
}
int
LLVMFuzzerInitialize(int *argc, char ***argv)
{
unsigned int mutate_flags = 0;
for (int i = 0; i < *argc; i++)
if (strcmp((*argv)[i], "--fido-debug") == 0) {
debug = 1;
} else if (strncmp((*argv)[i], "--fido-save-seed=", 17) == 0) {
exit(save_seed((*argv)[i]));
} else if (strncmp((*argv)[i], "--fido-mutate=", 14) == 0) {
parse_mutate_flags((*argv)[i], &mutate_flags);
}
if (mutate_flags)
flags = mutate_flags;
return 0;
}
int
LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
{
struct param *p;
if (size > MAXCORPUS)
return 0;
if (++test_total % 100000 == 0 && debug) {
double r = (double)test_fail/(double)test_total * 100.0;
fprintf(stderr, "%s: %llu/%llu (%.2f%%)\n", __func__,
test_fail, test_total, r);
}
if ((p = unpack(data, size)) == NULL)
test_fail++;
else {
fuzz_save_corpus = 0;
test(p);
if (fuzz_save_corpus && save_corpus(p) < 0)
fprintf(stderr, "%s: failed to save corpus\n",
__func__);
free(p);
}
return 0;
}
size_t
LLVMFuzzerCustomMutator(uint8_t *data, size_t size, size_t maxsize,
unsigned int seed) NO_MSAN
{
struct param *p;
uint8_t blob[MAXCORPUS];
size_t blob_len;
memset(&p, 0, sizeof(p));
#ifdef WITH_MSAN
__msan_unpoison(data, maxsize);
#endif
if (++mutate_total % 100000 == 0 && debug) {
double r = (double)mutate_fail/(double)mutate_total * 100.0;
fprintf(stderr, "%s: %llu/%llu (%.2f%%)\n", __func__,
mutate_fail, mutate_total, r);
}
if ((p = unpack(data, size)) == NULL) {
mutate_fail++;
return pack_dummy(data, maxsize);
}
mutate(p, seed, flags);
if ((blob_len = pack(blob, sizeof(blob), p)) == 0 ||
blob_len > sizeof(blob) || blob_len > maxsize) {
mutate_fail++;
free(p);
return 0;
}
free(p);
memcpy(data, blob, blob_len);
return blob_len;
}
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