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/*
american fuzzy lop++ - LLVM CmpLog instrumentation
--------------------------------------------------
Written by Andrea Fioraldi <andreafioraldi@gmail.com>
Copyright 2015, 2016 Google Inc. All rights reserved.
Copyright 2019-2024 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:
https://www.apache.org/licenses/LICENSE-2.0
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <iostream>
#include <list>
#include <string>
#include <fstream>
#include <sys/time.h>
#include "llvm/Config/llvm-config.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/Passes/PassPlugin.h"
#include "llvm/Passes/PassBuilder.h"
#include "llvm/IR/PassManager.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#if LLVM_VERSION_MAJOR < 17
#include "llvm/Transforms/IPO/PassManagerBuilder.h"
#endif
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Pass.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Verifier.h"
#include "llvm/IR/DebugInfo.h"
#include <set>
#include "afl-llvm-common.h"
using namespace llvm;
namespace {
class CmplogSwitches : public PassInfoMixin<CmplogSwitches> {
public:
CmplogSwitches() {
initInstrumentList();
}
PreservedAnalyses run(Module &M, ModuleAnalysisManager &MAM);
private:
bool hookInstrs(Module &M);
};
} // namespace
extern "C" ::llvm::PassPluginLibraryInfo LLVM_ATTRIBUTE_WEAK
llvmGetPassPluginInfo() {
return {LLVM_PLUGIN_API_VERSION, "cmplogswitches", "v0.1",
/* lambda to insert our pass into the pass pipeline. */
[](PassBuilder &PB) {
#if LLVM_VERSION_MAJOR <= 13
using OptimizationLevel = typename PassBuilder::OptimizationLevel;
#endif
PB.registerOptimizerLastEPCallback([](ModulePassManager &MPM,
OptimizationLevel OL
#if LLVM_VERSION_MAJOR >= 20
,
ThinOrFullLTOPhase Phase
#endif
) {
MPM.addPass(CmplogSwitches());
});
}};
}
template <class Iterator>
Iterator Unique(Iterator first, Iterator last) {
while (first != last) {
Iterator next(first);
last = std::remove(++next, last, *first);
first = next;
}
return last;
}
bool CmplogSwitches::hookInstrs(Module &M) {
std::vector<SwitchInst *> switches;
LLVMContext &C = M.getContext();
Type *VoidTy = Type::getVoidTy(C);
IntegerType *Int8Ty = IntegerType::getInt8Ty(C);
IntegerType *Int16Ty = IntegerType::getInt16Ty(C);
IntegerType *Int32Ty = IntegerType::getInt32Ty(C);
IntegerType *Int64Ty = IntegerType::getInt64Ty(C);
FunctionCallee c1 = M.getOrInsertFunction("__cmplog_ins_hook1", VoidTy,
Int8Ty, Int8Ty, Int8Ty);
FunctionCallee cmplogHookIns1 = c1;
FunctionCallee c2 = M.getOrInsertFunction("__cmplog_ins_hook2", VoidTy,
Int16Ty, Int16Ty, Int8Ty);
FunctionCallee cmplogHookIns2 = c2;
FunctionCallee c4 = M.getOrInsertFunction("__cmplog_ins_hook4", VoidTy,
Int32Ty, Int32Ty, Int8Ty);
FunctionCallee cmplogHookIns4 = c4;
FunctionCallee c8 = M.getOrInsertFunction("__cmplog_ins_hook8", VoidTy,
Int64Ty, Int64Ty, Int8Ty);
FunctionCallee cmplogHookIns8 = c8;
GlobalVariable *AFLCmplogPtr = M.getNamedGlobal("__afl_cmp_map");
if (!AFLCmplogPtr) {
AFLCmplogPtr = new GlobalVariable(M, PointerType::get(Int8Ty, 0), false,
GlobalValue::ExternalWeakLinkage, 0,
"__afl_cmp_map");
}
Constant *Null = Constant::getNullValue(PointerType::get(Int8Ty, 0));
/* iterate over all functions, bbs and instruction and add suitable calls */
for (auto &F : M) {
if (!isInInstrumentList(&F, MNAME)) continue;
for (auto &BB : F) {
SwitchInst *switchInst = nullptr;
if ((switchInst = dyn_cast<SwitchInst>(BB.getTerminator()))) {
if (switchInst->getNumCases() > 1) { switches.push_back(switchInst); }
}
}
}
// unique the collected switches
switches.erase(Unique(switches.begin(), switches.end()), switches.end());
// Instrument switch values for cmplog
if (switches.size()) {
if (!be_quiet)
errs() << "Hooking " << switches.size() << " switch instructions\n";
for (auto &SI : switches) {
Value *Val = SI->getCondition();
unsigned int max_size = Val->getType()->getIntegerBitWidth(), cast_size;
unsigned char do_cast = 0;
if (!SI->getNumCases() || max_size < 16) {
// if (!be_quiet) errs() << "skip trivial switch..\n";
continue;
}
if (max_size % 8) {
max_size = (((max_size / 8) + 1) * 8);
do_cast = 1;
}
IRBuilder<> IRB2(SI->getParent());
IRB2.SetInsertPoint(SI);
LoadInst *CmpPtr =
IRB2.CreateLoad(PointerType::get(Int8Ty, 0), AFLCmplogPtr);
CmpPtr->setMetadata(M.getMDKindID("nosanitize"), MDNode::get(C, None));
auto is_not_null = IRB2.CreateICmpNE(CmpPtr, Null);
auto ThenTerm = SplitBlockAndInsertIfThen(is_not_null, SI, false);
IRBuilder<> IRB(ThenTerm);
if (max_size > 128) {
if (!be_quiet) {
fprintf(stderr,
"Cannot handle this switch bit size: %u (truncating)\n",
max_size);
}
max_size = 128;
do_cast = 1;
}
// do we need to cast?
switch (max_size) {
case 8:
case 16:
case 32:
case 64:
case 128:
cast_size = max_size;
break;
default:
cast_size = 128;
do_cast = 1;
}
Value *CompareTo = Val;
if (do_cast) {
CompareTo =
IRB.CreateIntCast(CompareTo, IntegerType::get(C, cast_size), false);
}
for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end(); i != e;
++i) {
ConstantInt *cint = i->getCaseValue();
if (cint) {
std::vector<Value *> args;
args.push_back(CompareTo);
Value *new_param = cint;
if (do_cast) {
new_param =
IRB.CreateIntCast(cint, IntegerType::get(C, cast_size), false);
}
if (new_param) {
args.push_back(new_param);
ConstantInt *attribute = ConstantInt::get(Int8Ty, 1);
args.push_back(attribute);
if (cast_size != max_size) {
ConstantInt *bitsize =
ConstantInt::get(Int8Ty, (max_size / 8) - 1);
args.push_back(bitsize);
}
switch (cast_size) {
case 8:
IRB.CreateCall(cmplogHookIns1, args);
break;
case 16:
IRB.CreateCall(cmplogHookIns2, args);
break;
case 32:
IRB.CreateCall(cmplogHookIns4, args);
break;
case 64:
IRB.CreateCall(cmplogHookIns8, args);
break;
case 128:
#ifdef WORD_SIZE_64
if (max_size == 128) {
IRB.CreateCall(cmplogHookIns16, args);
} else {
IRB.CreateCall(cmplogHookInsN, args);
}
#endif
break;
default:
break;
}
}
}
}
}
}
if (switches.size())
return true;
else
return false;
}
PreservedAnalyses CmplogSwitches::run(Module &M, ModuleAnalysisManager &MAM) {
if (getenv("AFL_QUIET") == NULL)
printf("Running cmplog-switches-pass by andreafioraldi@gmail.com\n");
else
be_quiet = 1;
bool ret = hookInstrs(M);
verifyModule(M);
if (ret == false)
return PreservedAnalyses::all();
else
return PreservedAnalyses();
}
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