/* american fuzzy lop++ - LLVM-mode wrapper for clang ------------------------------------------------ Written by Laszlo Szekeres and Michal Zalewski LLVM integration design comes from Laszlo Szekeres. Copyright 2015, 2016 Google Inc. All rights reserved. Copyright 2019-2020 AFLplusplus Project. 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 clang, similar in most respects to ../afl-gcc. 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 "alloc-inl.h" #include #include #include #include #include #include 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 */ static u8 llvm_fullpath[PATH_MAX]; static u8 cmplog_mode; /* 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) { #ifdef __ANDROID__ tmp = alloc_printf("%s/afl-llvm-rt.so", afl_path); #else tmp = alloc_printf("%s/afl-llvm-rt.o", afl_path); #endif 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 = '/'; #ifdef __ANDROID__ tmp = alloc_printf("%s/afl-llvm-rt.so", afl_path); #else tmp = alloc_printf("%s/afl-llvm-rt.o", dir); #endif if (!access(tmp, R_OK)) { obj_path = dir; ck_free(tmp); return; } ck_free(tmp); ck_free(dir); } #ifdef __ANDROID__ if (!access(AFL_PATH "/afl-llvm-rt.so", R_OK)) { #else if (!access(AFL_PATH "/afl-llvm-rt.o", R_OK)) { #endif obj_path = AFL_PATH; return; } FATAL( "Unable to find 'afl-llvm-rt.o' or 'afl-llvm-pass.so.cc'. 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, bit_mode = 0; u8 has_llvm_config = 0; u8* name; cc_params = ck_alloc((argc + 128) * sizeof(u8*)); name = strrchr(argv[0], '/'); if (!name) name = argv[0]; else ++name; has_llvm_config = (strlen(LLVM_BINDIR) > 0); if (!strcmp(name, "afl-clang-fast++")) { u8* alt_cxx = getenv("AFL_CXX"); if (has_llvm_config) snprintf(llvm_fullpath, sizeof(llvm_fullpath), "%s/clang++", LLVM_BINDIR); else sprintf(llvm_fullpath, "clang++"); cc_params[0] = alt_cxx ? alt_cxx : (u8*)llvm_fullpath; } else { u8* alt_cc = getenv("AFL_CC"); if (has_llvm_config) snprintf(llvm_fullpath, sizeof(llvm_fullpath), "%s/clang", LLVM_BINDIR); else sprintf(llvm_fullpath, "clang"); cc_params[0] = alt_cc ? alt_cc : (u8*)llvm_fullpath; } /* There are three ways to compile with afl-clang-fast. In the traditional mode, we use afl-llvm-pass.so, then there is libLLVMInsTrim.so which is much faster but has less coverage. Finally there is the experimental 'trace-pc-guard' mode, we use native LLVM instrumentation callbacks instead. For trace-pc-guard see: http://clang.llvm.org/docs/SanitizerCoverage.html#tracing-pcs-with-guards */ // laf if (getenv("LAF_SPLIT_SWITCHES") || getenv("AFL_LLVM_LAF_SPLIT_SWITCHES")) { cc_params[cc_par_cnt++] = "-Xclang"; cc_params[cc_par_cnt++] = "-load"; cc_params[cc_par_cnt++] = "-Xclang"; cc_params[cc_par_cnt++] = alloc_printf("%s/split-switches-pass.so", obj_path); } if (getenv("LAF_TRANSFORM_COMPARES") || getenv("AFL_LLVM_LAF_TRANSFORM_COMPARES")) { cc_params[cc_par_cnt++] = "-Xclang"; cc_params[cc_par_cnt++] = "-load"; cc_params[cc_par_cnt++] = "-Xclang"; cc_params[cc_par_cnt++] = alloc_printf("%s/compare-transform-pass.so", obj_path); } if (getenv("LAF_SPLIT_COMPARES") || getenv("AFL_LLVM_LAF_SPLIT_COMPARES")) { cc_params[cc_par_cnt++] = "-Xclang"; cc_params[cc_par_cnt++] = "-load"; cc_params[cc_par_cnt++] = "-Xclang"; cc_params[cc_par_cnt++] = alloc_printf("%s/split-compares-pass.so", obj_path); } // /laf if (cmplog_mode) { cc_params[cc_par_cnt++] = "-fsanitize-coverage=trace-pc-guard,trace-cmp"; } else { #ifdef USE_TRACE_PC cc_params[cc_par_cnt++] = "-fsanitize-coverage=trace-pc-guard"; // edge coverage by default // cc_params[cc_par_cnt++] = "-mllvm"; // cc_params[cc_par_cnt++] = // "-fsanitize-coverage=trace-cmp,trace-div,trace-gep"; // cc_params[cc_par_cnt++] = "-sanitizer-coverage-block-threshold=0"; #else if (getenv("USE_TRACE_PC") || getenv("AFL_USE_TRACE_PC") || getenv("AFL_LLVM_USE_TRACE_PC") || getenv("AFL_TRACE_PC")) { cc_params[cc_par_cnt++] = "-fsanitize-coverage=trace-pc-guard"; // edge coverage by default } else { cc_params[cc_par_cnt++] = "-Xclang"; cc_params[cc_par_cnt++] = "-load"; cc_params[cc_par_cnt++] = "-Xclang"; if (getenv("AFL_LLVM_INSTRIM") != NULL || getenv("INSTRIM_LIB") != NULL) cc_params[cc_par_cnt++] = alloc_printf("%s/libLLVMInsTrim.so", obj_path); else cc_params[cc_par_cnt++] = alloc_printf("%s/afl-llvm-pass.so", obj_path); } #endif /* ^USE_TRACE_PC */ } cc_params[cc_par_cnt++] = "-Qunused-arguments"; /* Detect stray -v calls from ./configure scripts. */ if (argc == 1 && !strcmp(argv[1], "-v")) maybe_linking = 0; while (--argc) { u8* cur = *(++argv); if (!strcmp(cur, "-m32")) bit_mode = 32; if (!strcmp(cur, "armv7a-linux-androideabi")) bit_mode = 32; if (!strcmp(cur, "-m64")) bit_mode = 64; if (!strcmp(cur, "-x")) x_set = 1; if (!strcmp(cur, "-c") || !strcmp(cur, "-S") || !strcmp(cur, "-E")) 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; if (!strcmp(cur, "-Wl,-z,defs") || !strcmp(cur, "-Wl,--no-undefined")) continue; 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"; } } #ifdef USE_TRACE_PC if (getenv("USE_TRACE_PC") || getenv("AFL_USE_TRACE_PC") || getenv("AFL_LLVM_USE_TRACE_PC") || getenv("AFL_TRACE_PC")) if (getenv("AFL_INST_RATIO")) FATAL("AFL_INST_RATIO not available at compile time with 'trace-pc'."); #endif /* USE_TRACE_PC */ 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__ "__attribute__((visibility(\"default\"))) " "int _L(unsigned int) __asm__(\"___afl_persistent_loop\"); " #else "__attribute__((visibility(\"default\"))) " "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__ "__attribute__((visibility(\"default\"))) " "void _I(void) __asm__(\"___afl_manual_init\"); " #else "__attribute__((visibility(\"default\"))) " "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"; } #ifndef __ANDROID__ switch (bit_mode) { case 0: if (cmplog_mode) cc_params[cc_par_cnt++] = alloc_printf("%s/afl-llvm-cmplog-rt.o", obj_path); else cc_params[cc_par_cnt++] = alloc_printf("%s/afl-llvm-rt.o", obj_path); break; case 32: if (cmplog_mode) cc_params[cc_par_cnt++] = alloc_printf("%s/afl-llvm-cmplog-rt-32.o", obj_path); else cc_params[cc_par_cnt++] = alloc_printf("%s/afl-llvm-rt-32.o", obj_path); if (access(cc_params[cc_par_cnt - 1], R_OK)) FATAL("-m32 is not supported by your compiler"); break; case 64: if (cmplog_mode) cc_params[cc_par_cnt++] = alloc_printf("%s/afl-llvm-cmplog-rt-64.o", obj_path); else cc_params[cc_par_cnt++] = alloc_printf("%s/afl-llvm-rt-64.o", obj_path); if (access(cc_params[cc_par_cnt - 1], R_OK)) FATAL("-m64 is not supported by your compiler"); break; } #endif } cc_params[cc_par_cnt] = NULL; } /* Main entry point */ int main(int argc, char** argv) { if (argc < 2 || strcmp(argv[1], "-h") == 0) { #ifdef USE_TRACE_PC printf( cCYA "afl-clang-fast" VERSION cRST " [tpcg] by \n" #else printf( cCYA "afl-clang-fast" VERSION cRST " by \n" #endif /* ^USE_TRACE_PC */ "\n" "afl-clang-fast[++] [options]\n" "\n" "This is a helper application for afl-fuzz. It serves as a drop-in " "replacement\n" "for clang, 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-clang-fast ./configure\n" " CXX=%s/afl-clang-fast++ ./configure\n\n" "In contrast to the traditional afl-clang tool, this version is " "implemented as\n" "an LLVM pass and tends to offer improved performance with slow " "programs.\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" "afl-clang-fast was built for llvm %s with the llvm binary path of " "\"%s\".\n\n", BIN_PATH, BIN_PATH, LLVM_VERSION, LLVM_BINDIR); exit(1); } else if (isatty(2) && !getenv("AFL_QUIET")) { #ifdef USE_TRACE_PC SAYF(cCYA "afl-clang-fast" VERSION cRST " [tpcg] by \n"); #warning \ "You do not need to specifically compile with USE_TRACE_PC anymore, setting the environment variable AFL_LLVM_USE_TRACE_PC is enough." #else SAYF(cCYA "afl-clang-fast" VERSION cRST " by \n"); #endif /* ^USE_TRACE_PC */ } cmplog_mode = getenv("AFL_CMPLOG") || getenv("AFL_LLVM_CMPLOG"); if (cmplog_mode) printf("CmpLog mode by \n"); #ifndef __ANDROID__ find_obj(argv[0]); #endif edit_params(argc, argv); /* int i = 0; printf("EXEC:"); while (cc_params[i] != NULL) printf(" %s", cc_params[i++]); printf("\n"); */ execvp(cc_params[0], (char**)cc_params); FATAL("Oops, failed to execute '%s' - check your PATH", cc_params[0]); return 0; }