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- /*
- american fuzzy lop - wrapper for GCC and clang
- ----------------------------------------------
- Written and maintained by Michal Zalewski <lcamtuf@google.com>
- Copyright 2013, 2014, 2015 Google Inc. All rights reserved.
- Licensed under the Apache License, Version 2.0 (the "License");
- you may not use this file except in compliance with the License.
- You may obtain a copy of the License at:
- http://www.apache.org/licenses/LICENSE-2.0
- This program is a drop-in replacement for GCC or clang. The most common way
- of using it is to pass the path to afl-gcc or afl-clang via CC when invoking
- ./configure.
- (Of course, use CXX and point it to afl-g++ / afl-clang++ for C++ code.)
- The wrapper needs to know the path to afl-as (renamed to 'as'). The default
- is /usr/local/lib/afl/. A convenient way to specify alternative directories
- would be to set AFL_PATH.
- If AFL_HARDEN is set, the wrapper will compile the target app with various
- hardening options that may help detect memory management issues more
- reliably. You can also specify AFL_USE_ASAN to enable ASAN.
- If you want to call a non-default compiler as a next step of the chain,
- specify its location via AFL_CC or AFL_CXX.
- */
- #define AFL_MAIN
- #include "config.h"
- #include "types.h"
- #include "debug.h"
- #include "alloc-inl.h"
- #include <stdio.h>
- #include <unistd.h>
- #include <stdlib.h>
- #include <string.h>
- static u8* as_path; /* Path to the AFL 'as' wrapper */
- static u8** cc_params; /* Parameters passed to the real CC */
- static u32 cc_par_cnt = 1; /* Param count, including argv0 */
- static u8 be_quiet, /* Quiet mode */
- clang_mode; /* Invoked as afl-clang*? */
- /* Try to find our "fake" GNU assembler in AFL_PATH or at the location derived
- from argv[0]. If that fails, abort. */
- static void find_as(u8* argv0) {
- u8 *afl_path = getenv("AFL_PATH");
- u8 *slash, *tmp;
- if (afl_path) {
- tmp = alloc_printf("%s/as", afl_path);
- if (!access(tmp, X_OK)) {
- as_path = afl_path;
- ck_free(tmp);
- return;
- }
- ck_free(tmp);
- }
- slash = strrchr(argv0, '/');
- if (slash) {
- u8 *dir;
- *slash = 0;
- dir = ck_strdup(argv0);
- *slash = '/';
- tmp = alloc_printf("%s/afl-as", dir);
- if (!access(tmp, X_OK)) {
- as_path = dir;
- ck_free(tmp);
- return;
- }
- ck_free(tmp);
- ck_free(dir);
- }
- if (!access(AFL_PATH "/as", X_OK)) {
- as_path = AFL_PATH;
- return;
- }
- FATAL("Unable to find AFL wrapper binary for 'as'. Please set AFL_PATH");
-
- }
- /* Copy argv to cc_params, making the necessary edits. */
- static void edit_params(u32 argc, char** argv) {
- u8 fortify_set = 0, asan_set = 0;
- u8 *name;
- #if defined(__FreeBSD__) && defined(__x86_64__)
- u8 m32_set = 0;
- #endif
- cc_params = ck_alloc((argc + 128) * sizeof(u8*));
- name = strrchr(argv[0], '/');
- if (!name) name = argv[0]; else name++;
- if (!strncmp(name, "afl-clang", 9)) {
- clang_mode = 1;
- setenv(CLANG_ENV_VAR, "1", 1);
- if (!strcmp(name, "afl-clang++")) {
- u8* alt_cxx = getenv("AFL_CXX");
- cc_params[0] = alt_cxx ? alt_cxx : (u8*)"clang++";
- } else {
- u8* alt_cc = getenv("AFL_CC");
- cc_params[0] = alt_cc ? alt_cc : (u8*)"clang";
- }
- } else {
- /* With GCJ and Eclipse installed, you can actually compile Java! The
- instrumentation will work (amazingly). Alas, unhandled exceptions do
- not call abort(), so afl-fuzz would need to be modified to equate
- non-zero exit codes with crash conditions when working with Java
- binaries. Meh. */
- #ifdef __APPLE__
- if (!strcmp(name, "afl-g++")) cc_params[0] = getenv("AFL_CXX");
- else if (!strcmp(name, "afl-gcj")) cc_params[0] = getenv("AFL_GCJ");
- else cc_params[0] = getenv("AFL_CC");
- if (!cc_params[0]) {
- SAYF("\n" cLRD "[-] " cRST
- "On Apple systems, 'gcc' is usually just a wrapper for clang. Please use the\n"
- " 'afl-clang' utility instead of 'afl-gcc'. If you really have GCC installed,\n"
- " set AFL_CC or AFL_CXX to specify the correct path to that compiler.\n");
- FATAL("AFL_CC or AFL_CXX required on MacOS X");
- }
- #else
- if (!strcmp(name, "afl-g++")) {
- u8* alt_cxx = getenv("AFL_CXX");
- cc_params[0] = alt_cxx ? alt_cxx : (u8*)"g++";
- } else if (!strcmp(name, "afl-gcj")) {
- u8* alt_cc = getenv("AFL_GCJ");
- cc_params[0] = alt_cc ? alt_cc : (u8*)"gcj";
- } else {
- u8* alt_cc = getenv("AFL_CC");
- cc_params[0] = alt_cc ? alt_cc : (u8*)"gcc";
- }
- #endif /* __APPLE__ */
- }
- while (--argc) {
- u8* cur = *(++argv);
- if (!strncmp(cur, "-B", 2)) {
- if (!be_quiet) WARNF("-B is already set, overriding");
- if (!cur[2] && argc > 1) { argc--; argv++; }
- continue;
- }
- if (!strcmp(cur, "-integrated-as")) continue;
- if (!strcmp(cur, "-pipe")) continue;
- #if defined(__FreeBSD__) && defined(__x86_64__)
- if (!strcmp(cur, "-m32")) m32_set = 1;
- #endif
- if (!strcmp(cur, "-fsanitize=address") ||
- !strcmp(cur, "-fsanitize=memory")) asan_set = 1;
- if (strstr(cur, "FORTIFY_SOURCE")) fortify_set = 1;
- cc_params[cc_par_cnt++] = cur;
- }
- cc_params[cc_par_cnt++] = "-B";
- cc_params[cc_par_cnt++] = as_path;
- if (clang_mode)
- cc_params[cc_par_cnt++] = "-no-integrated-as";
- if (getenv("AFL_HARDEN")) {
- cc_params[cc_par_cnt++] = "-fstack-protector-all";
- if (!fortify_set)
- cc_params[cc_par_cnt++] = "-D_FORTIFY_SOURCE=2";
- }
- if (asan_set) {
- /* Pass this on to afl-as to adjust map density. */
- setenv("AFL_USE_ASAN", "1", 1);
- } else if (getenv("AFL_USE_ASAN")) {
- if (getenv("AFL_USE_MSAN"))
- FATAL("ASAN and MSAN are mutually exclusive");
- if (getenv("AFL_HARDEN"))
- FATAL("ASAN and AFL_HARDEN are mutually exclusive");
- cc_params[cc_par_cnt++] = "-U_FORTIFY_SOURCE";
- cc_params[cc_par_cnt++] = "-fsanitize=address";
- } else if (getenv("AFL_USE_MSAN")) {
- if (getenv("AFL_USE_ASAN"))
- FATAL("ASAN and MSAN are mutually exclusive");
- if (getenv("AFL_HARDEN"))
- FATAL("MSAN and AFL_HARDEN are mutually exclusive");
- cc_params[cc_par_cnt++] = "-U_FORTIFY_SOURCE";
- cc_params[cc_par_cnt++] = "-fsanitize=memory";
- }
- if (!getenv("AFL_DONT_OPTIMIZE")) {
- #if defined(__FreeBSD__) && defined(__x86_64__)
- /* On 64-bit FreeBSD systems, clang -g -m32 is broken, but -m32 itself
- works OK. This has nothing to do with us, but let's avoid triggering
- that bug. */
- if (!clang_mode || !m32_set)
- cc_params[cc_par_cnt++] = "-g";
- #else
- cc_params[cc_par_cnt++] = "-g";
- #endif
- cc_params[cc_par_cnt++] = "-O3";
- cc_params[cc_par_cnt++] = "-funroll-loops";
- /* Two indicators that you're building for fuzzing; one of them is
- AFL-specific, the other is shared with libfuzzer. */
- cc_params[cc_par_cnt++] = "-D__AFL_COMPILER=1";
- cc_params[cc_par_cnt++] = "-DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION=1";
- }
- if (getenv("AFL_NO_BUILTIN")) {
- cc_params[cc_par_cnt++] = "-fno-builtin-strcmp";
- cc_params[cc_par_cnt++] = "-fno-builtin-strncmp";
- cc_params[cc_par_cnt++] = "-fno-builtin-strcasecmp";
- cc_params[cc_par_cnt++] = "-fno-builtin-strncasecmp";
- cc_params[cc_par_cnt++] = "-fno-builtin-memcmp";
- cc_params[cc_par_cnt++] = "-fno-builtin-strstr";
- cc_params[cc_par_cnt++] = "-fno-builtin-strcasestr";
- }
- cc_params[cc_par_cnt] = NULL;
- }
- /* Main entry point */
- int main(int argc, char** argv) {
- if (isatty(2) && !getenv("AFL_QUIET")) {
- SAYF(cCYA "afl-cc " cBRI VERSION cRST " by <lcamtuf@google.com>\n");
- } else be_quiet = 1;
- if (argc < 2) {
- SAYF("\n"
- "This is a helper application for afl-fuzz. It serves as a drop-in replacement\n"
- "for gcc or clang, letting you recompile third-party code with the required\n"
- "runtime instrumentation. A common use pattern would be one of the following:\n\n"
- " CC=%s/afl-gcc ./configure\n"
- " CXX=%s/afl-g++ ./configure\n\n"
- "You can specify custom next-stage toolchain via AFL_CC, AFL_CXX, and AFL_AS.\n"
- "Setting AFL_HARDEN enables hardening optimizations in the compiled code.\n\n",
- BIN_PATH, BIN_PATH);
- exit(1);
- }
- find_as(argv[0]);
- edit_params(argc, argv);
- execvp(cc_params[0], (char**)cc_params);
- FATAL("Oops, failed to execute '%s' - check your PATH", cc_params[0]);
- return 0;
- }
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