| /* |
| american fuzzy lop++ - GCC wrapper for GCC plugin |
| ------------------------------------------------ |
| |
| Written by Austin Seipp <aseipp@pobox.com> and |
| Laszlo Szekeres <lszekeres@google.com> and |
| Michal Zalewski |
| |
| GCC integration design is based on the LLVM design, which comes |
| from Laszlo Szekeres. |
| |
| Copyright 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, similar in most |
| respects to ../afl-gcc, but with compiler instrumentation through a |
| plugin. It tries to figure out compilation mode, adds a bunch of |
| flags, and then calls the real compiler. |
| |
| */ |
| |
| #define AFL_MAIN |
| |
| #include "config.h" |
| #include "types.h" |
| #include "debug.h" |
| #include "common.h" |
| #include "alloc-inl.h" |
| |
| #include <stdio.h> |
| #include <unistd.h> |
| #include <stdlib.h> |
| #include <string.h> |
| |
| static u8 * obj_path; /* Path to runtime libraries */ |
| static u8 **cc_params; /* Parameters passed to the real CC */ |
| static u32 cc_par_cnt = 1; /* Param count, including argv0 */ |
| u8 use_stdin = 0; /* dummy */ |
| u8 be_quiet; |
| |
| /* Try to find the runtime libraries. If that fails, abort. */ |
| |
| static void find_obj(u8 *argv0) { |
| |
| u8 *afl_path = getenv("AFL_PATH"); |
| u8 *slash, *tmp; |
| |
| if (afl_path) { |
| |
| tmp = alloc_printf("%s/afl-gcc-rt.o", afl_path); |
| |
| if (!access(tmp, R_OK)) { |
| |
| obj_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-gcc-rt.o", dir); |
| |
| if (!access(tmp, R_OK)) { |
| |
| obj_path = dir; |
| ck_free(tmp); |
| return; |
| |
| } |
| |
| ck_free(tmp); |
| ck_free(dir); |
| |
| } |
| |
| if (!access(AFL_PATH "/afl-gcc-rt.o", R_OK)) { |
| |
| obj_path = AFL_PATH; |
| return; |
| |
| } |
| |
| FATAL( |
| "Unable to find 'afl-gcc-rt.o' or 'afl-gcc-pass.so'. 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, x_set = 0, maybe_linking = 1; |
| u8 *name; |
| |
| cc_params = ck_alloc((argc + 128) * sizeof(u8 *)); |
| |
| name = strrchr(argv[0], '/'); |
| if (!name) |
| name = argv[0]; |
| else |
| ++name; |
| |
| if (!strcmp(name, "afl-g++-fast")) { |
| |
| u8 *alt_cxx = getenv("AFL_CXX"); |
| cc_params[0] = alt_cxx ? alt_cxx : (u8 *)AFL_GCC_CXX; |
| |
| } else { |
| |
| u8 *alt_cc = getenv("AFL_CC"); |
| cc_params[0] = alt_cc ? alt_cc : (u8 *)AFL_GCC_CC; |
| |
| } |
| |
| char *fplugin_arg = alloc_printf("-fplugin=%s/afl-gcc-pass.so", obj_path); |
| cc_params[cc_par_cnt++] = fplugin_arg; |
| |
| /* Detect stray -v calls from ./configure scripts. */ |
| |
| if (argc == 1 && !strcmp(argv[1], "-v")) maybe_linking = 0; |
| |
| while (--argc) { |
| |
| u8 *cur = *(++argv); |
| |
| #if defined(__x86_64__) |
| if (!strcmp(cur, "-m32")) FATAL("-m32 is not supported"); |
| #endif |
| |
| if (!strcmp(cur, "-x")) x_set = 1; |
| |
| if (!strcmp(cur, "-c") || !strcmp(cur, "-S") || !strcmp(cur, "-E") || |
| !strcmp(cur, "-v")) |
| maybe_linking = 0; |
| |
| if (!strcmp(cur, "-fsanitize=address") || !strcmp(cur, "-fsanitize=memory")) |
| asan_set = 1; |
| |
| if (strstr(cur, "FORTIFY_SOURCE")) fortify_set = 1; |
| |
| if (!strcmp(cur, "-shared")) maybe_linking = 0; |
| |
| cc_params[cc_par_cnt++] = cur; |
| |
| } |
| |
| 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) { |
| |
| 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_USE_UBSAN")) { |
| |
| cc_params[cc_par_cnt++] = "-fsanitize=undefined"; |
| cc_params[cc_par_cnt++] = "-fsanitize-undefined-trap-on-error"; |
| cc_params[cc_par_cnt++] = "-fno-sanitize-recover=all"; |
| |
| } |
| |
| if (!getenv("AFL_DONT_OPTIMIZE")) { |
| |
| cc_params[cc_par_cnt++] = "-g"; |
| cc_params[cc_par_cnt++] = "-O3"; |
| cc_params[cc_par_cnt++] = "-funroll-loops"; |
| |
| } |
| |
| 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-bcmp"; |
| cc_params[cc_par_cnt++] = "-fno-builtin-strstr"; |
| cc_params[cc_par_cnt++] = "-fno-builtin-strcasestr"; |
| |
| } |
| |
| #ifdef USEMMAP |
| cc_params[cc_par_cnt++] = "-lrt"; |
| #endif |
| |
| cc_params[cc_par_cnt++] = "-D__AFL_HAVE_MANUAL_CONTROL=1"; |
| cc_params[cc_par_cnt++] = "-D__AFL_COMPILER=1"; |
| cc_params[cc_par_cnt++] = "-DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION=1"; |
| |
| /* When the user tries to use persistent or deferred forkserver modes by |
| appending a single line to the program, we want to reliably inject a |
| signature into the binary (to be picked up by afl-fuzz) and we want |
| to call a function from the runtime .o file. This is unnecessarily |
| painful for three reasons: |
| |
| 1) We need to convince the compiler not to optimize out the signature. |
| This is done with __attribute__((used)). |
| |
| 2) We need to convince the linker, when called with -Wl,--gc-sections, |
| not to do the same. This is done by forcing an assignment to a |
| 'volatile' pointer. |
| |
| 3) We need to declare __afl_persistent_loop() in the global namespace, |
| but doing this within a method in a class is hard - :: and extern "C" |
| are forbidden and __attribute__((alias(...))) doesn't work. Hence the |
| __asm__ aliasing trick. |
| |
| */ |
| |
| cc_params[cc_par_cnt++] = |
| "-D__AFL_LOOP(_A)=" |
| "({ static volatile char *_B __attribute__((used)); " |
| " _B = (char*)\"" PERSIST_SIG |
| "\"; " |
| #ifdef __APPLE__ |
| "int _L(unsigned int) __asm__(\"___afl_persistent_loop\"); " |
| #else |
| "int _L(unsigned int) __asm__(\"__afl_persistent_loop\"); " |
| #endif /* ^__APPLE__ */ |
| "_L(_A); })"; |
| |
| cc_params[cc_par_cnt++] = |
| "-D__AFL_INIT()=" |
| "do { static volatile char *_A __attribute__((used)); " |
| " _A = (char*)\"" DEFER_SIG |
| "\"; " |
| #ifdef __APPLE__ |
| "void _I(void) __asm__(\"___afl_manual_init\"); " |
| #else |
| "void _I(void) __asm__(\"__afl_manual_init\"); " |
| #endif /* ^__APPLE__ */ |
| "_I(); } while (0)"; |
| |
| if (maybe_linking) { |
| |
| if (x_set) { |
| |
| cc_params[cc_par_cnt++] = "-x"; |
| cc_params[cc_par_cnt++] = "none"; |
| |
| } |
| |
| cc_params[cc_par_cnt++] = alloc_printf("%s/afl-gcc-rt.o", obj_path); |
| |
| } |
| |
| cc_params[cc_par_cnt] = NULL; |
| |
| } |
| |
| /* Main entry point */ |
| |
| int main(int argc, char **argv, char **envp) { |
| |
| if (argc < 2 || strcmp(argv[1], "-h") == 0) { |
| |
| printf( |
| cCYA |
| "afl-gcc-fast" VERSION cRST |
| " initially by <aseipp@pobox.com>, maintainer: hexcoder-\n" |
| "\n" |
| "afl-gcc-fast [options]\n" |
| "\n" |
| "This is a helper application for afl-fuzz. It serves as a drop-in " |
| "replacement\n" |
| "for gcc, letting you recompile third-party code with the required " |
| "runtime\n" |
| "instrumentation. A common use pattern would be one of the " |
| "following:\n\n" |
| |
| " CC=%s/afl-gcc-fast ./configure\n" |
| " CXX=%s/afl-g++-fast ./configure\n\n" |
| |
| "In contrast to the traditional afl-gcc tool, this version is " |
| "implemented as\n" |
| "a GCC plugin and tends to offer improved performance with slow " |
| "programs\n" |
| "(similarly to the LLVM plugin used by afl-clang-fast).\n\n" |
| |
| "Environment variables used:\n" |
| "AFL_CC: path to the C compiler to use\n" |
| "AFL_CXX: path to the C++ compiler to use\n" |
| "AFL_PATH: path to instrumenting pass and runtime (afl-gcc-rt.*o)\n" |
| "AFL_DONT_OPTIMIZE: disable optimization instead of -O3\n" |
| "AFL_NO_BUILTIN: compile for use with libtokencap.so\n" |
| "AFL_INST_RATIO: percentage of branches to instrument\n" |
| "AFL_QUIET: suppress verbose output\n" |
| "AFL_DEBUG: enable developer debugging output\n" |
| "AFL_HARDEN: adds code hardening to catch memory bugs\n" |
| "AFL_USE_ASAN: activate address sanitizer\n" |
| "AFL_USE_MSAN: activate memory sanitizer\n" |
| "AFL_USE_UBSAN: activate undefined behaviour sanitizer\n" |
| "AFL_GCC_WHITELIST: enable whitelisting (selective instrumentation)\n" |
| |
| "\nafl-gcc-fast was built for gcc %s with the gcc binary path of " |
| "\"%s\".\n\n", |
| BIN_PATH, BIN_PATH, GCC_VERSION, GCC_BINDIR); |
| |
| exit(1); |
| |
| } else if ((isatty(2) && !getenv("AFL_QUIET")) || |
| |
| getenv("AFL_DEBUG") != NULL) { |
| |
| SAYF(cCYA "afl-gcc-fast" VERSION cRST |
| " initially by <aseipp@pobox.com>, maintainer: hexcoder-\n"); |
| |
| if (getenv("AFL_GCC_WHITELIST") == NULL) { |
| |
| SAYF(cYEL "Warning:" cRST |
| " using afl-gcc-fast without using AFL_GCC_WHITELIST currently " |
| "produces worse results than afl-gcc. Even better, use " |
| "llvm_mode for now.\n"); |
| |
| } |
| |
| } else |
| |
| be_quiet = 1; |
| |
| check_environment_vars(envp); |
| |
| find_obj(argv[0]); |
| |
| edit_params(argc, argv); |
| /*if (isatty(2) && !getenv("AFL_QUIET")) { |
| |
| printf("Calling \"%s\" with:\n", cc_params[0]); |
| for(int i=1; i<cc_par_cnt; i++) printf("%s\n", cc_params[i]); |
| |
| } |
| |
| */ |
| execvp(cc_params[0], (char **)cc_params); |
| |
| FATAL("Oops, failed to execute '%s' - check your PATH", cc_params[0]); |
| |
| return 0; |
| |
| } |
| |
