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Diffstat (limited to 'gcc_plugin/afl-gcc-fast.c')
| -rw-r--r-- | gcc_plugin/afl-gcc-fast.c | 348 |
1 files changed, 348 insertions, 0 deletions
diff --git a/gcc_plugin/afl-gcc-fast.c b/gcc_plugin/afl-gcc-fast.c new file mode 100644 index 00000000..057b44cc --- /dev/null +++ b/gcc_plugin/afl-gcc-fast.c @@ -0,0 +1,348 @@ +/* + 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 "../include/debug.h" +#include "../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 */ + +/* 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*)"g++"; + + } else { + + u8* alt_cc = getenv("AFL_CC"); + cc_params[0] = alt_cc ? alt_cc : (u8*)"gcc"; + + } + + 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_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) { + + 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" + + "You can specify custom next-stage toolchain via AFL_CC and AFL_CXX. " + "Setting\n" + "AFL_HARDEN enables hardening optimizations in the compiled code.\n\n", + BIN_PATH, BIN_PATH); + + exit(1); + + } else if (isatty(2) && !getenv("AFL_QUIET")) { + + SAYF(cCYA "afl-gcc-fast" VERSION cRST + " initially by <aseipp@pobox.com>, maintainer: hexcoder-\n"); + + } + + 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; + +} + |