diff options
| -rw-r--r-- | Makefile | 7 | ||||
| -rw-r--r-- | afl-fuzz.c | 62 | ||||
| -rw-r--r-- | docs/ChangeLog | 4 | ||||
| -rw-r--r-- | docs/PATCHES | 1 | ||||
| -rw-r--r-- | docs/README | 3 | ||||
| -rw-r--r-- | gcc_plugin/Makefile | 75 | ||||
| -rw-r--r-- | gcc_plugin/README.gcc | 157 | ||||
| -rw-r--r-- | gcc_plugin/afl-gcc-fast.c | 283 | ||||
| -rw-r--r-- | gcc_plugin/afl-gcc-pass.so.cc | 372 | ||||
| -rw-r--r-- | gcc_plugin/afl-gcc-rt.o.c | 224 |
10 files changed, 1137 insertions, 51 deletions
diff --git a/Makefile b/Makefile index 6b580381..69bd7535 100644 --- a/Makefile +++ b/Makefile @@ -181,7 +181,7 @@ all_done: test_build .NOTPARALLEL: clean clean: - rm -f $(PROGS) afl-as as afl-g++ afl-clang afl-clang++ *.o *~ a.out core core.[1-9][0-9]* *.stackdump test .test .test1 .test2 test-instr .test-instr0 .test-instr1 qemu_mode/qemu-3.1.0.tar.xz afl-qemu-trace + rm -f $(PROGS) afl-as as afl-g++ afl-clang afl-clang++ *.o *~ a.out core core.[1-9][0-9]* *.stackdump test .test .test1 .test2 test-instr .test-instr0 .test-instr1 qemu_mode/qemu-3.1.0.tar.xz afl-qemu-trace afl-gcc-fast afl-gcc-pass.so afl-gcc-rt.o afl-g++-fast rm -rf out_dir qemu_mode/qemu-3.1.0 $(MAKE) -C llvm_mode clean $(MAKE) -C libdislocator clean @@ -193,6 +193,7 @@ install: all install -m 755 $(PROGS) $(SH_PROGS) $${DESTDIR}$(BIN_PATH) rm -f $${DESTDIR}$(BIN_PATH)/afl-as if [ -f afl-qemu-trace ]; then install -m 755 afl-qemu-trace $${DESTDIR}$(BIN_PATH); fi + if [ -f afl-gcc-fast ]; then set e; install -m 755 afl-gcc-fast $${DESTDIR}$(BIN_PATH); ln -sf afl-gcc-fast $${DESTDIR}$(BIN_PATH)/afl-g++-fast; install -m 755 afl-gcc-pass.so afl-gcc-rt.o $${DESTDIR}$(HELPER_PATH); fi ifndef AFL_TRACE_PC if [ -f afl-clang-fast -a -f libLLVMInsTrim.so -a -f afl-llvm-rt.o ]; then set -e; install -m 755 afl-clang-fast $${DESTDIR}$(BIN_PATH); ln -sf afl-clang-fast $${DESTDIR}$(BIN_PATH)/afl-clang-fast++; install -m 755 libLLVMInsTrim.so afl-llvm-pass.so afl-llvm-rt.o $${DESTDIR}$(HELPER_PATH); fi else @@ -204,7 +205,9 @@ endif if [ -f split-compares-pass.so ]; then set -e; install -m 755 split-compares-pass.so $${DESTDIR}$(HELPER_PATH); fi if [ -f split-switches-pass.so ]; then set -e; install -m 755 split-switches-pass.so $${DESTDIR}$(HELPER_PATH); fi - set -e; for i in afl-g++ afl-clang afl-clang++; do ln -sf afl-gcc $${DESTDIR}$(BIN_PATH)/$$i; done + set -e; ln -sf afl-gcc $${DESTDIR}$(BIN_PATH)/afl-g++ + set -e; if [ -f afl-clang-fast ] ; then ln -sf afl-clang-fast $${DESTDIR}$(BIN_PATH)/afl-clang ; ln -sf afl-clang-fast $${DESTDIR}$(BIN_PATH)/afl-clang++ ; else ln -sf afl-gcc $${DESTDIR}$(BIN_PATH)/afl-clang ; ln -sf afl-gcc $${DESTDIR}$(BIN_PATH)/afl-clang++; fi + install -m 755 afl-as $${DESTDIR}$(HELPER_PATH) ln -sf afl-as $${DESTDIR}$(HELPER_PATH)/as install -m 644 docs/README docs/ChangeLog docs/*.txt $${DESTDIR}$(DOC_PATH) diff --git a/afl-fuzz.c b/afl-fuzz.c index 3a8e5750..81dff98c 100644 --- a/afl-fuzz.c +++ b/afl-fuzz.c @@ -5234,6 +5234,7 @@ static u32 calculate_score(struct queue_entry* q) { // MOpt mode if (limit_time_sig != 0 && max_depth - q->depth < 3) perf_score *= 2; + else if (perf_score < 1) perf_score = 1; // Add a lower bound to AFLFast's energy assignment strategies /* Make sure that we don't go over limit. */ @@ -10224,8 +10225,7 @@ static u8 core_fuzzing(char** argv) { stage_max = (doing_det ? HAVOC_CYCLES_INIT : HAVOC_CYCLES) * perf_score / havoc_div / 100; - } - else { + } else { static u8 tmp[32]; @@ -10243,20 +10243,13 @@ static u8 core_fuzzing(char** argv) { //for (; swarm_now < swarm_num; swarm_now++) { - - - if (key_puppet == 1) - { - if (unlikely(orig_hit_cnt_puppet == 0)) - { + if (key_puppet == 1) { + if (unlikely(orig_hit_cnt_puppet == 0)) { orig_hit_cnt_puppet = queued_paths + unique_crashes; last_limit_time_start = get_cur_time(); - SPLICE_CYCLES_puppet = (UR(SPLICE_CYCLES_puppet_up - SPLICE_CYCLES_puppet_low + 1) + SPLICE_CYCLES_puppet_low); } } - - { havoc_stage_puppet: @@ -10266,14 +10259,11 @@ static u8 core_fuzzing(char** argv) { splice_cycle variable is set, generate different descriptions and such. */ if (!splice_cycle) { - stage_name = "MOpt core avoc"; stage_short = "MOpt core havoc"; stage_max = (doing_det ? HAVOC_CYCLES_INIT : HAVOC_CYCLES) * perf_score / havoc_div / 100; - - } - else { + } else { static u8 tmp[32]; perf_score = orig_perf; sprintf(tmp, "MOpt core splice %u", splice_cycle); @@ -10282,31 +10272,20 @@ static u8 core_fuzzing(char** argv) { stage_max = SPLICE_HAVOC * perf_score / havoc_div / 100; } - - if (stage_max < HAVOC_MIN) stage_max = HAVOC_MIN; - temp_len = len; - orig_hit_cnt = queued_paths + unique_crashes; - havoc_queued = queued_paths; - - for (stage_cur = 0; stage_cur < stage_max; stage_cur++) { u32 use_stacking = 1 << (1 + UR(HAVOC_STACK_POW2)); - stage_cur_val = use_stacking; - - for (i = 0; i < operator_num; i++) - { + for (i = 0; i < operator_num; i++) { core_operator_cycles_puppet_v3[i] = core_operator_cycles_puppet_v2[i]; } - for (i = 0; i < use_stacking; i++) { switch (select_algorithm()) { @@ -10366,8 +10345,7 @@ static u8 core_fuzzing(char** argv) { if (UR(2)) { u32 pos = UR(temp_len - 1); *(u16*)(out_buf + pos) -= 1 + UR(ARITH_MAX); - } - else { + } else { u32 pos = UR(temp_len - 1); u16 num = 1 + UR(ARITH_MAX); *(u16*)(out_buf + pos) = @@ -10377,8 +10355,7 @@ static u8 core_fuzzing(char** argv) { if (UR(2)) { u32 pos = UR(temp_len - 1); *(u16*)(out_buf + pos) += 1 + UR(ARITH_MAX); - } - else { + } else { u32 pos = UR(temp_len - 1); u16 num = 1 + UR(ARITH_MAX); *(u16*)(out_buf + pos) = @@ -10394,8 +10371,7 @@ static u8 core_fuzzing(char** argv) { if (UR(2)) { u32 pos = UR(temp_len - 3); *(u32*)(out_buf + pos) -= 1 + UR(ARITH_MAX); - } - else { + } else { u32 pos = UR(temp_len - 3); u32 num = 1 + UR(ARITH_MAX); *(u32*)(out_buf + pos) = @@ -10405,8 +10381,7 @@ static u8 core_fuzzing(char** argv) { if (UR(2)) { u32 pos = UR(temp_len - 3); *(u32*)(out_buf + pos) += 1 + UR(ARITH_MAX); - } - else { + } else { u32 pos = UR(temp_len - 3); u32 num = 1 + UR(ARITH_MAX); *(u32*)(out_buf + pos) = @@ -10429,8 +10404,7 @@ static u8 core_fuzzing(char** argv) { if (UR(2)) { *(u16*)(out_buf + UR(temp_len - 1)) = interesting_16[UR(sizeof(interesting_16) >> 1)]; - } - else { + } else { *(u16*)(out_buf + UR(temp_len - 1)) = SWAP16( interesting_16[UR(sizeof(interesting_16) >> 1)]); } @@ -10446,8 +10420,7 @@ static u8 core_fuzzing(char** argv) { if (UR(2)) { *(u32*)(out_buf + UR(temp_len - 3)) = interesting_32[UR(sizeof(interesting_32) >> 2)]; - } - else { + } else { *(u32*)(out_buf + UR(temp_len - 3)) = SWAP32( interesting_32[UR(sizeof(interesting_32) >> 2)]); } @@ -10466,7 +10439,6 @@ static u8 core_fuzzing(char** argv) { break; - case 13: { /* Delete bytes. We're making this a bit more likely @@ -10507,8 +10479,7 @@ static u8 core_fuzzing(char** argv) { clone_len = choose_block_len(temp_len); clone_from = UR(temp_len - clone_len + 1); - } - else { + } else { clone_len = choose_block_len(HAVOC_BLK_XL); clone_from = 0; @@ -10575,17 +10546,10 @@ static u8 core_fuzzing(char** argv) { } - tmp_core_time += 1; - - - u64 temp_total_found = queued_paths + unique_crashes; - - - if (common_fuzz_stuff(argv, out_buf, temp_len)) goto abandon_entry_puppet; diff --git a/docs/ChangeLog b/docs/ChangeLog index 116029ea..8c1aa994 100644 --- a/docs/ChangeLog +++ b/docs/ChangeLog @@ -17,6 +17,10 @@ sending a mail to <afl-users+subscribe@googlegroups.com>. Version ++2.52d (tbd): ----------------------------- + - if llvm_mode was compiled, afl-clang/afl-clang++ will point to these + instead of afl-gcc + - added gcc_plugin which is like llvm_mode but for gcc. This version + supports gcc version 5 to 8. See gcc_plugin/README (https://github.com/T12z/afl) - added instrim, a much faster llvm_mode instrumentation at the cost of path discovery. See llvm_mode/README.instrim (https://github.com/csienslab/instrim) - added MOpt (github.com/puppet-meteor/MOpt-AFL) mode, see docs/README.MOpt diff --git a/docs/PATCHES b/docs/PATCHES index f6ca9284..78050208 100644 --- a/docs/PATCHES +++ b/docs/PATCHES @@ -17,6 +17,7 @@ afl-qemu-optimize-entrypoint.diff by mh(at)mh-sec(dot)de afl-qemu-speed.diff by abiondo on github afl-qemu-optimize-map.diff by mh(at)mh-sec(dot)de ++ gcc_plugin (https://github.com/T12z/afl) + instrim (https://github.com/csienslab/instrim) was integrated + MOpt (github.com/puppet-meteor/MOpt-AFL) was imported + AFLfast additions (github.com/mboehme/aflfast) were incorporated. diff --git a/docs/README b/docs/README index 3a6c2921..a8ec715b 100644 --- a/docs/README +++ b/docs/README @@ -25,6 +25,9 @@ american fuzzy lop plus plus Also newly integrated is instrim, a very effective CFG llvm_mode instrumentation implementation from https://github.com/csienslab/instrim + Similar to llvm_mode a gcc_plugin that supports versions 5 to 8 is + now available (from https://github.com/T12z/afl) + A more thorough list is available in the PATCHES file. So all in all this is the best-of AFL that is currently out there :-) diff --git a/gcc_plugin/Makefile b/gcc_plugin/Makefile new file mode 100644 index 00000000..721ce0ad --- /dev/null +++ b/gcc_plugin/Makefile @@ -0,0 +1,75 @@ +# +# american fuzzy lop - GCC plugin instrumentation +# ----------------------------------------------- +# +# Written by Austin Seipp <aseipp@pobox.com> and +# Laszlo Szekeres <lszekeres@google.com> and +# Michal Zalewski <lcamtuf@google.com> +# +# 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 +# + +PREFIX ?= /usr/local +HELPER_PATH = $(PREFIX)/lib/afl +BIN_PATH = $(PREFIX)/bin + +CFLAGS ?= -O3 -g -funroll-loops +CFLAGS += -Wall -D_FORTIFY_SOURCE=2 -Wno-pointer-sign \ + -DAFL_PATH=\"$(HELPER_PATH)\" -DBIN_PATH=\"$(BIN_PATH)\" \ + +CXXFLAGS ?= -O3 -g -funroll-loops +CXXEFLAGS := $(CXXFLAGS) -Wall -D_FORTIFY_SOURCE=2 + +CC ?= gcc +CXX ?= g++ + +PLUGIN_FLAGS = -fPIC -fno-rtti -I"$(shell $(CC) -print-file-name=plugin)/include" + +PROGS = ../afl-gcc-fast ../afl-gcc-pass.so ../afl-gcc-rt.o + +all: test_deps $(PROGS) test_build all_done + +test_deps: + @echo "[*] Checking for working '$(CC)'..." + @which $(CC) >/dev/null 2>&1 || ( echo "[-] Oops, can't find '$(CC)'. Make sure that it's in your \$$PATH (or set \$$CC and \$$CXX)."; exit 1 ) + @echo "[*] Checking for '../afl-showmap'..." + @test -f ../afl-showmap || ( echo "[-] Oops, can't find '../afl-showmap'. Be sure to compile AFL first."; exit 1 ) + @echo "[+] All set and ready to build." + +../afl-gcc-fast: afl-gcc-fast.c | test_deps + $(CC) $(CFLAGS) $< -o $@ $(LDFLAGS) + ln -sf afl-gcc-fast ../afl-g++-fast + +../afl-gcc-pass.so: afl-gcc-pass.so.cc | test_deps + $(CXX) $(CXXEFLAGS) $(PLUGIN_FLAGS) -shared $< -o $@ + +../afl-gcc-rt.o: afl-gcc-rt.o.c | test_deps + $(CC) $(CFLAGS) -fPIC -c $< -o $@ + +test_build: $(PROGS) + @echo "[*] Testing the CC wrapper and instrumentation output..." +# unset AFL_USE_ASAN AFL_USE_MSAN; AFL_QUIET=1 AFL_INST_RATIO=100 AFL_PATH=. AFL_CC=$(CC) ../afl-gcc-fast $(CFLAGS) ../test-instr.c -o test-instr $(LDFLAGS) + unset AFL_USE_ASAN AFL_USE_MSAN; AFL_INST_RATIO=100 AFL_PATH=. AFL_CC=$(CC) ../afl-gcc-fast $(CFLAGS) ../test-instr.c -o test-instr $(LDFLAGS) + echo 0 | ../afl-showmap -m none -q -o .test-instr0 ./test-instr + echo 1 | ../afl-showmap -m none -q -o .test-instr1 ./test-instr + @rm -f test-instr + @cmp -s .test-instr0 .test-instr1; DR="$$?"; rm -f .test-instr0 .test-instr1; if [ "$$DR" = "0" ]; then echo; echo "Oops, the instrumentation does not seem to be behaving correctly!"; echo; echo "Please ping <lcamtuf@google.com> to troubleshoot the issue."; echo; exit 1; fi + @echo "[+] All right, the instrumentation seems to be working!" + +all_done: test_build + @echo "[+] All done! You can now use '../afl-gcc-fast' to compile programs." + +.NOTPARALLEL: clean + +clean: + rm -f *.o *.so *~ a.out core core.[1-9][0-9]* test-instr .test-instr0 .test-instr1 + rm -f $(PROGS) ../afl-g++-fast diff --git a/gcc_plugin/README.gcc b/gcc_plugin/README.gcc new file mode 100644 index 00000000..b3e9c853 --- /dev/null +++ b/gcc_plugin/README.gcc @@ -0,0 +1,157 @@ +=========================================== +Fast GCC-based instrumentation for afl-fuzz +=========================================== + + (See ../docs/README for the general instruction manual.) + (See ../llvm_mode/README.llvm for the LLVM-based instrumentation.) + +1) Introduction +--------------- + +The code in this directory allows you to instrument programs for AFL using +true compiler-level instrumentation, instead of the more crude +assembly-level rewriting approach taken by afl-gcc and afl-clang. This has +several interesting properties: + + - The compiler can make many optimizations that are hard to pull off when + manually inserting assembly. As a result, some slow, CPU-bound programs will + run up to around 2x faster. + + The gains are less pronounced for fast binaries, where the speed is limited + chiefly by the cost of creating new processes. In such cases, the gain will + probably stay within 10%. + + - The instrumentation is CPU-independent. At least in principle, you should + be able to rely on it to fuzz programs on non-x86 architectures (after + building afl-fuzz with AFL_NOX86=1). + + - Because the feature relies on the internals of GCC, it is gcc-specific + and will *not* work with LLVM (see ../llvm_plugin for an alternative). + +Once this implementation is shown to be sufficiently robust and portable, it +will probably replace afl-gcc. For now, it can be built separately and +co-exists with the original code. + +The idea and much of the implementation comes from Laszlo Szekeres. + +2) How to use +------------- + +In order to leverage this mechanism, you need to have GCC and the plugin headers +installed on your system. That should be all you need. On Debian machines, these +headers can be acquired by installing the `gcc-<VERSION>-plugin-dev` packages. + +To build the instrumentation itself, type 'make'. This will generate binaries +called afl-gcc-fast and afl-g++-fast in the parent directory. Once this +is done, you can instrument third-party code in a way similar to the standard +operating mode of AFL, e.g.: + + CC=/path/to/afl/afl-gcc-fast ./configure [...options...] + make + +Be sure to also include CXX set to afl-g++-fast for C++ code. + +The tool honors roughly the same environmental variables as afl-gcc (see +../docs/env_variables.txt). This includes AFL_INST_RATIO, AFL_USE_ASAN, +AFL_HARDEN, and AFL_DONT_OPTIMIZE. + +Note: if you want the GCC plugin to be installed on your system for all +users, you need to build it before issuing 'make install' in the parent +directory. + +3) Gotchas, feedback, bugs +-------------------------- + +This is an early-stage mechanism, so field reports are welcome. You can send bug +reports to <aseipp@pobox.com>. + +4) Bonus feature #1: deferred instrumentation +--------------------------------------------- + +AFL tries to optimize performance by executing the targeted binary just once, +stopping it just before main(), and then cloning this "master" process to get +a steady supply of targets to fuzz. + +Although this approach eliminates much of the OS-, linker- and libc-level +costs of executing the program, it does not always help with binaries that +perform other time-consuming initialization steps - say, parsing a large config +file before getting to the fuzzed data. + +In such cases, it's beneficial to initialize the forkserver a bit later, once +most of the initialization work is already done, but before the binary attempts +to read the fuzzed input and parse it; in some cases, this can offer a 10x+ +performance gain. You can implement delayed initialization in LLVM mode in a +fairly simple way. + +First, locate a suitable location in the code where the delayed cloning can +take place. This needs to be done with *extreme* care to avoid breaking the +binary. In particular, the program will probably malfunction if you select +a location after: + + - The creation of any vital threads or child processes - since the forkserver + can't clone them easily. + + - The initialization of timers via setitimer() or equivalent calls. + + - The creation of temporary files, network sockets, offset-sensitive file + descriptors, and similar shared-state resources - but only provided that + their state meaningfully influences the behavior of the program later on. + + - Any access to the fuzzed input, including reading the metadata about its + size. + +With the location selected, add this code in the appropriate spot: + +#ifdef __AFL_HAVE_MANUAL_CONTROL + __AFL_INIT(); +#endif + +You don't need the #ifdef guards, but they will make the program still work as +usual when compiled with a tool other than afl-gcc-fast/afl-clang-fast. + +Finally, recompile the program with afl-gcc-fast (afl-gcc or afl-clang will +*not* generate a deferred-initialization binary) - and you should be all set! + +5) Bonus feature #2: persistent mode +------------------------------------ + +Some libraries provide APIs that are stateless, or whose state can be reset in +between processing different input files. When such a reset is performed, a +single long-lived process can be reused to try out multiple test cases, +eliminating the need for repeated fork() calls and the associated OS overhead. + +The basic structure of the program that does this would be: + + while (__AFL_LOOP(1000)) { + + /* Read input data. */ + /* Call library code to be fuzzed. */ + /* Reset state. */ + + } + + /* Exit normally */ + +The numerical value specified within the loop controls the maximum number +of iterations before AFL will restart the process from scratch. This minimizes +the impact of memory leaks and similar glitches; 1000 is a good starting point. + +A more detailed template is shown in ../experimental/persistent_demo/. +Similarly to the previous mode, the feature works only with afl-gcc-fast or +afl-clang-fast; #ifdef guards can be used to suppress it when using other +compilers. + +Note that as with the previous mode, the feature is easy to misuse; if you +do not reset the critical state fully, you may end up with false positives or +waste a whole lot of CPU power doing nothing useful at all. Be particularly +wary of memory leaks and the state of file descriptors. + +When running in this mode, the execution paths will inherently vary a bit +depending on whether the input loop is being entered for the first time or +executed again. To avoid spurious warnings, the feature implies +AFL_NO_VAR_CHECK and hides the "variable path" warnings in the UI. + +PS. Because there are task switches still involved, the mode isn't as fast as +"pure" in-process fuzzing offered, say, by LLVM's LibFuzzer; but it is a lot +faster than the normal fork() model, and compared to in-process fuzzing, +should be a lot more robust. diff --git a/gcc_plugin/afl-gcc-fast.c b/gcc_plugin/afl-gcc-fast.c new file mode 100644 index 00000000..018b3f5f --- /dev/null +++ b/gcc_plugin/afl-gcc-fast.c @@ -0,0 +1,283 @@ +/* + american fuzzy lop - GCC wrapper for GCC plugin + ------------------------------------------------ + + Written by Austin Seipp <aseipp@pobox.com> and + Laszlo Szekeres <lszekeres@google.com> and + Michal Zalewski <lcamtuf@google.com> + + 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 "../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 + 64) * 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; + + 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; + + 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")) { + + cc_params[cc_par_cnt++] = "-fsanitize=address"; + + if (getenv("AFL_USE_MSAN")) + FATAL("ASAN and MSAN are mutually exclusive"); + + } else if (getenv("AFL_USE_MSAN")) { + + cc_params[cc_par_cnt++] = "-fsanitize=memory"; + + if (getenv("AFL_USE_ASAN")) + FATAL("ASAN and MSAN are mutually exclusive"); + + } + + } + + if (!getenv("AFL_DONT_OPTIMIZE")) { + + cc_params[cc_par_cnt++] = "-g"; + cc_params[cc_par_cnt++] = "-O3"; + cc_params[cc_par_cnt++] = "-funroll-loops"; + + } + + cc_params[cc_par_cnt++] = "-D__AFL_HAVE_MANUAL_CONTROL=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 (isatty(2) && !getenv("AFL_QUIET")) { + + SAYF(cCYA "afl-gcc-fast" cRST " initial version 1.94 by <aseipp@pobox.com>, updated to " cBRI VERSION cRST " by <thorsten.schulz@uni-rostock.de>\n"); + + } + + if (argc < 2) { + + SAYF("\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); + + } + + + 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; + +} diff --git a/gcc_plugin/afl-gcc-pass.so.cc b/gcc_plugin/afl-gcc-pass.so.cc new file mode 100644 index 00000000..8d1888ef --- /dev/null +++ b/gcc_plugin/afl-gcc-pass.so.cc @@ -0,0 +1,372 @@ +// +// There are two TODOs in this file: +// - dont instrument blocks that are uninterested +// - implement whitelist feature +// + +/* + american fuzzy lop - GCC instrumentation pass + --------------------------------------------- + + Written by Austin Seipp <aseipp@pobox.com> with bits from + Emese Revfy <re.emese@gmail.com> + + Updated by Thorsten Schulz <thorsten.schulz@uni-rostock.de> + + GCC integration design is based on the LLVM design, which comes + from Laszlo Szekeres. Some of the boilerplate code below for + afl_pass to adapt to different GCC versions was taken from Emese + Revfy's Size Overflow plugin for GCC, licensed under the GPLv2/v3. + + (NOTE: this plugin code is under GPLv3, in order to comply with the + GCC runtime library exception, which states that you may distribute + "Target Code" from the compiler under a license of your choice, as + long as the "Compilation Process" is "Eligible", and contains no + GPL-incompatible software in GCC "during the process of + transforming high level code to target code". In this case, the + plugin will be used to generate "Target Code" during the + "Compilation Process", and thus it must be GPLv3 to be "eligible".) + + Copyright (C) 2015 Austin Seipp + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. + + */ + +//#define BUILD_INLINE_INST + +#include "../config.h" +#include "../debug.h" + +/* clear helper AFL types pulls in, which intervene with gcc-plugin geaders from GCC-8 */ +#ifdef likely +#undef likely +#endif +#ifdef unlikely +#undef unlikely +#endif + + +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> + +#include <gcc-plugin.h> +#include <plugin-version.h> +#include <diagnostic.h> +#include <tree.h> +#include <tree-ssa.h> +#include <tree-pass.h> +#include <tree-ssa-alias.h> +#include <basic-block.h> +#include <gimple-expr.h> +#include <gimple.h> +#include <gimple-iterator.h> +#include <version.h> +#include <toplev.h> +#include <intl.h> +#include <context.h> +#include <stringpool.h> +#include <cgraph.h> +#include <cfgloop.h> + +/* -------------------------------------------------------------------------- */ +/* -- AFL instrumentation pass ---------------------------------------------- */ + +static int be_quiet = 0; +static unsigned int inst_ratio = 100; +static bool inst_ext = true; /* I reckon inline is broken / unfunctional */ + + +static unsigned int ext_call_instrument(function *fun) { + /* Instrument all the things! */ + basic_block bb; + unsigned finst_blocks = 0; + unsigned fcnt_blocks = 0; + + FOR_ALL_BB_FN(bb, fun) { + gimple_seq fcall; + gimple_seq seq = NULL; + gimple_stmt_iterator bentry; + + if (!fcnt_blocks++) continue; /* skip block 0 */ + + // TODO: if the predecessor does not have to destinations + // then skip this block :TODO + + /* Bail on this block if we trip the specified ratio */ + if (R(100) >= inst_ratio) continue; + + /* Make up cur_loc */ + + unsigned int rand_loc = R(MAP_SIZE); + tree cur_loc = build_int_cst(uint64_type_node, rand_loc); + + /* Update bitmap via external call */ + /* to quote: + * /+ Trace a basic block with some ID +/ + * void __afl_trace(u16 x); + */ + + tree fntype = build_function_type_list( + void_type_node, /* return */ + uint16_type_node, /* args */ + NULL_TREE); /* done */ + tree fndecl = build_fn_decl("__afl_trace", fntype); + TREE_STATIC(fndecl) = 1; /* Defined elsewhere */ + TREE_PUBLIC(fndecl) = 1; /* Public */ + DECL_EXTERNAL(fndecl) = 1; /* External linkage */ + DECL_ARTIFICIAL(fndecl) = 1; /* Injected by compiler */ + + fcall = gimple_build_call(fndecl, 1, cur_loc); /* generate the function _call_ to above built reference, with *1* parameter -> the random const for the location */ + gimple_seq_add_stmt(&seq, fcall); /* and insert into a sequence */ + + /* Done - grab the entry to the block and insert sequence */ + bentry = gsi_start_bb(bb); + gsi_insert_seq_before(&bentry, seq, GSI_SAME_STMT); + + finst_blocks++; + } + fcnt_blocks--; /* discard the first in the count */ + + /* Say something nice. */ + if (!be_quiet) { + if (!finst_blocks) + WARNF(G_("No instrumentation targets found in " cBRI "%s" cRST ), + function_name(fun)); + else if (finst_blocks < fcnt_blocks) + OKF(G_("Instrumented %2u /%2u locations in " cBRI "%s" cRST ), + finst_blocks, fcnt_blocks, + function_name(fun)); + else + OKF(G_("Instrumented %2u locations in " cBRI "%s" cRST ), + finst_blocks, + function_name(fun)); + } + + return 0; +} + +static unsigned int inline_instrument(function *fun) { +#ifdef BUILD_INLINE_INST /* ifdef inline away, so I don't have to refactor it */ + /* Instrument all the things! */ + basic_block bb; + unsigned finst_blocks = 0; + unsigned fcnt_blocks = 0; + + /* Set up global type declarations */ + tree map_type = build_pointer_type(unsigned_char_type_node); + tree map_ptr_g = build_decl(UNKNOWN_LOCATION, VAR_DECL, get_identifier_with_length("__afl_area_ptr",14), map_type); + TREE_USED(map_ptr_g) = 1; + TREE_STATIC(map_ptr_g) = 1; /* Defined elsewhere */ + DECL_EXTERNAL(map_ptr_g) = 1; /* External linkage */ + DECL_PRESERVE_P(map_ptr_g) = 1; + DECL_ARTIFICIAL(map_ptr_g) = 1; + rest_of_decl_compilation(map_ptr_g, 1, 0); + + tree prev_loc_g = build_decl(UNKNOWN_LOCATION, VAR_DECL, get_identifier_with_length("__afl_prev_loc",14), uint16_type_node); + TREE_USED(prev_loc_g) = 1; + TREE_STATIC(prev_loc_g) = 1; /* Defined elsewhere */ + DECL_EXTERNAL(prev_loc_g) = 1; /* External linkage */ + DECL_PRESERVE_P(prev_loc_g) = 1; + DECL_ARTIFICIAL(prev_loc_g) = 1; + rest_of_decl_compilation(prev_loc_g, 1, 0); + + FOR_ALL_BB_FN(bb, fun) { + gimple *g; + gimple_seq seq = NULL; + gimple_stmt_iterator bentry; + + if (!fcnt_blocks++) continue; /* skip block 0 */ + + /* Bail on this block if we trip the specified ratio */ + if (R(100) >= inst_ratio) continue; + + /* Make up cur_loc */ + + unsigned int rand_loc = R(MAP_SIZE); + tree cur_loc = build_int_cst(uint64_type_node, rand_loc); + + /* Load prev_loc, xor with cur_loc */ + + tree area_off = create_tmp_var(uint64_type_node, "area_off"); + g = gimple_build_assign(area_off, BIT_XOR_EXPR, prev_loc_g, cur_loc); + gimple_seq_add_stmt(&seq, g); // area_off = prev_loc ^ cur_loc + + /* Update bitmap */ + +// tree zero = build_int_cst(unsigned_char_type_node, 0); + tree one = build_int_cst(unsigned_char_type_node, 1); + + tree tmp1 = create_tmp_var(map_type, "tmp1"); + g = gimple_build_assign(tmp1, PLUS_EXPR, map_ptr_g, area_off); + gimple_seq_add_stmt(&seq, g); // tmp1 = __afl_area_ptr + area_off + SAYF(G_("%d,"), fcnt_blocks); + + tree tmp2 = create_tmp_var(unsigned_char_type_node, "tmp2"); + //tree tmp1_ptr = build_simple_mem_ref_loc(UNKNOWN_LOCATION, tmp1); + g = gimple_build_assign(tmp2, INDIRECT_REF, tmp1); + gimple_seq_add_stmt(&seq, g); // tmp2 = *tmp1 + + tree tmp3 = create_tmp_var(unsigned_char_type_node, "tmp3"); + g = gimple_build_assign(tmp3, PLUS_EXPR, tmp2, one); + gimple_seq_add_stmt(&seq, g); // tmp3 = tmp2 + 1 + +// tree tmp4 = create_tmp_var(map_type, "tmp4"); +// g = gimple_build_assign(tmp4, PLUS_EXPR, map_ptr_g, area_off); +// gimple_seq_add_stmt(&seq, g); // tmp4 = __afl_area_ptr + area_off + +// tree deref2 = build2(MEM_REF, map_type, tmp4, zero); + tree deref2 = build4(ARRAY_REF, map_type, map_ptr_g, area_off, NULL, NULL); + g = gimple_build_assign(deref2, MODIFY_EXPR, tmp3); + gimple_seq_add_stmt(&seq, g); // *tmp4 = tmp3 + SAYF(G_("+%d,"), fcnt_blocks); + + /* Set prev_loc to cur_loc >> 1 */ + + tree shifted_loc = build_int_cst(TREE_TYPE(prev_loc_g), rand_loc >> 1); + g = gimple_build_assign(prev_loc_g, MODIFY_EXPR, shifted_loc); + gimple_seq_add_stmt(&seq, g); // __afl_pred_loc = cur_loc >> 1 + + /* Done - grab the entry to the block and insert sequence */ + + bentry = gsi_start_bb(bb); + gsi_insert_seq_before(&bentry, seq, GSI_SAME_STMT); + + inst_blocks++; + finst_blocks++; + } + + /* Say something nice. */ + if (!be_quiet) { + if (!finst_blocks) + WARNF(G_("No instrumentation targets found in " cBRI "%s" cRST ), + function_name(fun)); + else if (finst_blocks < fcnt_blocks) + OKF(G_("Instrumented %2u /%2u locations in " cBRI "%s" cRST ), + finst_blocks, fcnt_blocks, + function_name(fun)); + else + OKF(G_("Instrumented %2u locations in " cBRI "%s" cRST ), + finst_blocks, + function_name(fun)); + } + +#endif + return 0; +} + +/* -------------------------------------------------------------------------- */ +/* -- Boilerplate and initialization ---------------------------------------- */ + +static const struct pass_data afl_pass_data = { + + .type = GIMPLE_PASS, + .name = "afl-inst", + .optinfo_flags = OPTGROUP_NONE, + + .tv_id = TV_NONE, + .properties_required = 0, + .properties_provided = 0, + .properties_destroyed = 0, + .todo_flags_start = 0, + // NOTE(aseipp): it's very, very important to include + // at least 'TODO_update_ssa' here so that GCC will + // properly update the resulting SSA form, e.g., to + // include new PHI nodes for newly added symbols or + // names. Do not remove this. Do not taunt Happy Fun + // Ball. + .todo_flags_finish = TODO_update_ssa | TODO_verify_il | TODO_cleanup_cfg, +}; + +namespace { + +class afl_pass : public gimple_opt_pass { +private: + bool do_ext_call; + +public: + afl_pass(bool ext_call, gcc::context *g) : gimple_opt_pass(afl_pass_data, g), do_ext_call(ext_call) {} + + virtual unsigned int execute(function *fun) { + // TODO: implement whitelist feature here :TODO + return do_ext_call ? ext_call_instrument(fun) : inline_instrument(fun); + } +}; /* class afl_pass */ + +} /* anon namespace */ + +static struct opt_pass *make_afl_pass(bool ext_call, gcc::context *ctxt) { + return new afl_pass(ext_call, ctxt); +} + +/* -------------------------------------------------------------------------- */ +/* -- Initialization -------------------------------------------------------- */ + +int plugin_is_GPL_compatible = 1; + +static struct plugin_info afl_plugin_info = { + .version = "20181200", + .help = "AFL gcc plugin\n", +}; + +int plugin_init(struct plugin_name_args *plugin_info, + struct plugin_gcc_version *version) { + + struct register_pass_info afl_pass_info; + struct timeval tv; + struct timezone tz; + u32 rand_seed; + + /* Setup random() so we get Actually Random(TM) outputs from R() */ + gettimeofday(&tv, &tz); + rand_seed = tv.tv_sec ^ tv.tv_usec ^ getpid(); + srandom(rand_seed); + + /* Pass information */ + afl_pass_info.pass = make_afl_pass(inst_ext, g); + afl_pass_info.reference_pass_name = "ssa"; + afl_pass_info.ref_pass_instance_number = 1; + afl_pass_info.pos_op = PASS_POS_INSERT_AFTER; + + if (!plugin_default_version_check(version, &gcc_version)) { + FATAL(G_("Incompatible gcc/plugin versions!")); + } + + /* Show a banner */ + if (isatty(2) && !getenv("AFL_QUIET")) { + SAYF(G_(cCYA "afl-gcc-pass" cRST " initial version 1.94 by <aseipp@pobox.com>, updated to " cBRI VERSION cRST " by <thorsten.schulz@uni-rostock.de>\n")); + } else + be_quiet = 1; + + /* Decide instrumentation ratio */ + char* inst_ratio_str = getenv("AFL_INST_RATIO"); + + if (inst_ratio_str) { + if (sscanf(inst_ratio_str, "%u", &inst_ratio) != 1 || !inst_ratio || inst_ratio > 100) + FATAL(G_("Bad value of AFL_INST_RATIO (must be between 1 and 100)")); + else { + if (!be_quiet) + ACTF(G_("%s instrumentation at ratio of %u%% in %s mode."), + inst_ext ? G_("Call-based") : G_("Inline"), + inst_ratio, + getenv("AFL_HARDEN") ? G_("hardened") : G_("non-hardened")); + } + } + + /* Go go gadget */ + register_callback(plugin_info->base_name, PLUGIN_INFO, NULL, &afl_plugin_info); + register_callback(plugin_info->base_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &afl_pass_info); + return 0; +} diff --git a/gcc_plugin/afl-gcc-rt.o.c b/gcc_plugin/afl-gcc-rt.o.c new file mode 100644 index 00000000..4e238fa8 --- /dev/null +++ b/gcc_plugin/afl-gcc-rt.o.c @@ -0,0 +1,224 @@ +/* + american fuzzy lop - GCC plugin instrumentation bootstrap + --------------------------------------------------------- + + Written by Austin Seipp <aseipp@pobox.com> and + Laszlo Szekeres <lszekeres@google.com> and + Michal Zalewski <lcamtuf@google.com> + + 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 code is the rewrite of afl-as.h's main_payload. + +*/ + +#include "../config.h" +#include "../types.h" + +#include <stdlib.h> +#include <signal.h> +#include <unistd.h> +#include <assert.h> + +#include <sys/mman.h> +#include <sys/shm.h> +#include <sys/wait.h> +#include <sys/types.h> + + +/* Globals needed by the injected instrumentation. The __afl_area_initial region + is used for instrumentation output before __afl_map_shm() has a chance to run. + It will end up as .comm, so it shouldn't be too wasteful. */ + +u8 __afl_area_initial[MAP_SIZE]; +u8* __afl_area_ptr = __afl_area_initial; +u16 __afl_prev_loc; + + +/* Running in persistent mode? */ + +static u8 is_persistent; + +/* Trace a basic block with some ID */ +void __afl_trace(u16 x) { + u16 l = __afl_prev_loc; + u16 n = l ^ x; + *(__afl_area_ptr+n) += 1; + __afl_prev_loc = (x >> 1); + return; +} + +/* SHM setup. */ + +static void __afl_map_shm(void) { + + u8 *id_str = getenv(SHM_ENV_VAR); + + /* If we're running under AFL, attach to the appropriate region, replacing the + early-stage __afl_area_initial region that is needed to allow some really + hacky .init code to work correctly in projects such as OpenSSL. */ + + if (id_str) { + + u32 shm_id = atoi(id_str); + + __afl_area_ptr = shmat(shm_id, NULL, 0); + + /* Whooooops. */ + + if (__afl_area_ptr == (void *)-1) exit(1); + + /* Write something into the bitmap so that even with low AFL_INST_RATIO, + our parent doesn't give up on us. */ + + __afl_area_ptr[0] = 1; + + } + +} + + +/* Fork server logic. */ + +static void __afl_start_forkserver(void) { + + static u8 tmp[4]; + s32 child_pid; + + u8 child_stopped = 0; + + /* Phone home and tell the parent that we're OK. If parent isn't there, + assume we're not running in forkserver mode and just execute program. */ + + if (write(FORKSRV_FD + 1, tmp, 4) != 4) return; + + while (1) { + + u32 was_killed; + int status; + + /* Wait for parent by reading from the pipe. Abort if read fails. */ + + if (read(FORKSRV_FD, &was_killed, 4) != 4) exit(1); + + /* If we stopped the child in persistent mode, but there was a race + condition and afl-fuzz already issued SIGKILL, write off the old + process. */ + + if (child_stopped && was_killed) { + child_stopped = 0; + if (waitpid(child_pid, &status, 0) < 0) exit(1); + } + + if (!child_stopped) { + + /* Once woken up, create a clone of our process. */ + + child_pid = fork(); + if (child_pid < 0) exit(1); + + /* In child process: close fds, resume execution. */ + + if (!child_pid) { + + close(FORKSRV_FD); + close(FORKSRV_FD + 1); + return; + + } + + } else { + + /* Special handling for persistent mode: if the child is alive but + currently stopped, simply restart it with SIGCONT. */ + + kill(child_pid, SIGCONT); + child_stopped = 0; + + } + + /* In parent process: write PID to pipe, then wait for child. */ + + if (write(FORKSRV_FD + 1, &child_pid, 4) != 4) exit(1); + + if (waitpid(child_pid, &status, is_persistent ? WUNTRACED : 0) < 0) + exit(1); + + /* In persistent mode, the child stops itself with SIGSTOP to indicate + a successful run. In this case, we want to wake it up without forking + again. */ + + if (WIFSTOPPED(status)) child_stopped = 1; + + /* Relay wait status to pipe, then loop back. */ + + if (write(FORKSRV_FD + 1, &status, 4) != 4) exit(1); + + } + +} + + +/* A simplified persistent mode handler, used as explained in README.llvm. */ + +int __afl_persistent_loop(unsigned int max_cnt) { + + static u8 first_pass = 1; + static u32 cycle_cnt; + + if (first_pass) { + + cycle_cnt = max_cnt; + first_pass = 0; + return 1; + + } + + if (is_persistent && --cycle_cnt) { + + raise(SIGSTOP); + return 1; + + } else return 0; + +} + + +/* This one can be called from user code when deferred forkserver mode + is enabled. */ + +void __afl_manual_init(void) { + + static u8 init_done; + + if (!init_done) { + + __afl_map_shm(); + __afl_start_forkserver(); + init_done = 1; + + } + +} + + +/* Proper initialization routine. */ + +__attribute__((constructor(101))) void __afl_auto_init(void) { + + is_persistent = !!getenv(PERSIST_ENV_VAR); + + if (getenv(DEFER_ENV_VAR)) return; + + __afl_manual_init(); + +} |