diff options
Diffstat (limited to 'fuzz/libfuzzer.c')
| -rw-r--r-- | fuzz/libfuzzer.c | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/fuzz/libfuzzer.c b/fuzz/libfuzzer.c new file mode 100644 index 0000000..073ebe6 --- /dev/null +++ b/fuzz/libfuzzer.c @@ -0,0 +1,230 @@ +/* + * 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 <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; +} |