/*
* OptiMin, an optimal fuzzing corpus minimizer.
*
* Author: Adrian Herrera
*/
#include <cstdint>
#include <vector>
#include <llvm/ADT/DenseSet.h>
#include <llvm/ADT/DenseMap.h>
#include <llvm/ADT/SmallVector.h>
#include <llvm/ADT/StringExtras.h>
#include <llvm/ADT/StringMap.h>
#include <llvm/Support/Chrono.h>
#include <llvm/Support/CommandLine.h>
#include <llvm/Support/FileSystem.h>
#include <llvm/Support/MemoryBuffer.h>
#include <llvm/Support/Path.h>
#include <llvm/Support/Program.h>
#include <llvm/Support/WithColor.h>
#include "EvalMaxSAT.h"
#include "ProgressBar.h"
using namespace llvm;
namespace {
// -------------------------------------------------------------------------- //
// Classes
// -------------------------------------------------------------------------- //
/// Ensure seed weights default to 1
class Weight {
public:
Weight() : Weight(1){};
Weight(uint32_t V) : Value(V){};
operator unsigned() const {
return Value;
}
private:
const unsigned Value;
};
// -------------------------------------------------------------------------- //
// Typedefs
// -------------------------------------------------------------------------- //
/// AFL tuple (edge) ID
using AFLTupleID = uint32_t;
/// Pair of tuple ID and hit count
using AFLTuple = std::pair<AFLTupleID, /* Frequency */ unsigned>;
/// Coverage for a given seed file
using AFLCoverageVector = std::vector<AFLTuple>;
/// Maps seed file paths to a weight
using WeightsMap = StringMap<Weight>;
/// A seed identifier in the MaxSAT solver
using SeedID = int;
/// Associates seed identifiers to seed files
using MaxSATSeeds =
SmallVector<std::pair<SeedID, /* Seed file */ std::string>, 0>;
/// Set of literal identifiers
using MaxSATSeedSet = DenseSet<SeedID>;
/// Maps tuple IDs to the literal identifiers that "cover" that tuple
using MaxSATCoverageMap = DenseMap<AFLTupleID, MaxSATSeedSet>;
// -------------------------------------------------------------------------- //
// Global variables
// -------------------------------------------------------------------------- //
// This is based on the human class count in `count_class_human[256]` in
// `afl-showmap.c`
static constexpr uint32_t MAX_EDGE_FREQ = 8;
static sys::TimePoint<> StartTime, EndTime;
static std::chrono::seconds Duration;
static std::string AFLShowmapPath;
static bool TargetArgsHasAtAt = false;
static const auto ErrMsg = [] {
return WithColor(errs(), HighlightColor::Error) << "[-] ";
};
static const auto WarnMsg = [] {
return WithColor(errs(), HighlightColor::Warning) << "[-] ";
};
static const auto SuccMsg = [] {
return WithColor(outs(), HighlightColor::String) << "[+] ";
};
static const auto StatMsg = [] {
return WithColor(outs(), HighlightColor::Remark) << "[*] ";
};
static cl::opt<std::string> CorpusDir("i", cl::desc("Input directory"),
cl::value_desc("dir"), cl::Required);
static cl::opt<std::string> OutputDir("o", cl::desc("Output directory"),
cl::value_desc("dir"), cl::Required);
static cl::opt<bool> EdgesOnly("f", cl::desc("Include edge hit counts"),
cl::init(true));
static cl::opt<bool> ShowProgBar("p", cl::desc("Display progress bar"));
static cl::opt<std::string> WeightsFile("w", cl::desc("Weights file"),
cl::value_desc("csv"));
static cl::opt<std::string> TargetProg(cl::Positional,
cl::desc("<target program>"),
cl::Required);
static cl::list<std::string> TargetArgs(cl::ConsumeAfter,
cl::desc("[target args...]"));
static cl::opt<std::string> MemLimit(
"m", cl::desc("Memory limit for child process (default=none)"),
cl::value_desc("megs"), cl::init("none"));
static cl::opt<std::string> Timeout(
"t", cl::desc("Run time limit for child process (default=none)"),
cl::value_desc("msec"), cl::init("none"));
static cl::opt<bool> CrashMode(
"C", cl::desc("Keep crashing inputs, reject everything else"));
static cl::opt<bool> QemuMode("Q", cl::desc("Use binary-only instrumentation"));
} // anonymous namespace
// -------------------------------------------------------------------------- //
// Helper functions
// -------------------------------------------------------------------------- //
static void GetWeights(const MemoryBuffer &MB, WeightsMap &Weights) {
SmallVector<StringRef, 0> Lines;
MB.getBuffer().trim().split(Lines, '\n');
unsigned Weight = 0;
for (const auto &Line : Lines) {
const auto &[Seed, WeightStr] = Line.split(',');
if (to_integer(WeightStr, Weight, 10)) {
Weights.try_emplace(Seed, Weight);
} else {
WarnMsg() << "Failed to read weight for `" << Seed << "`. Skipping...\n";
}
}
}
[[nodiscard]] static std::error_code getAFLCoverage(const StringRef Seed,
AFLCoverageVector &Cov) {
Optional<StringRef> Redirects[] = {None, None, None};
std::error_code EC;
// Create temporary output file
SmallString<64> OutputPath;
if (EC = sys::fs::createTemporaryFile("showmap", "txt", OutputPath))
return EC;
// Prepare afl-showmap arguments
SmallVector<StringRef, 12> AFLShowmapArgs{
AFLShowmapPath, "-m", MemLimit, "-t", Timeout, "-q", "-o", OutputPath};
if (TargetArgsHasAtAt)
AFLShowmapArgs.append({"-A", Seed});
else
Redirects[/* stdin */ 0] = Seed;
if (QemuMode) AFLShowmapArgs.push_back("-Q");
if (CrashMode) AFLShowmapArgs.push_back("-C");
AFLShowmapArgs.append({"--", TargetProg});
AFLShowmapArgs.append(TargetArgs.begin(), TargetArgs.end());
// Run afl-showmap
const int RC = sys::ExecuteAndWait(AFLShowmapPath, AFLShowmapArgs,
/*env=*/None, Redirects);
if (RC) return std::make_error_code(std::errc::executable_format_error);
// Parse afl-showmap output
const auto CovOrErr = MemoryBuffer::getFile(OutputPath);
if (EC = CovOrErr.getError()) {
sys::fs::remove(OutputPath);
return EC;
}
SmallVector<StringRef, 0> Lines;
CovOrErr.get()->getBuffer().trim().split(Lines, '\n');
AFLTupleID Edge = 0;
unsigned Freq = 0;
for (const auto &Line : Lines) {
const auto &[EdgeStr, FreqStr] = Line.split(':');
to_integer(EdgeStr, Edge, 10);
to_integer(FreqStr, Freq, 10);
Cov.push_back({Edge, Freq});
}
return sys::fs::remove(OutputPath);
}
static inline void StartTimer(bool ShowProgBar) {
StartTime = std::chrono::system_clock::now();
}
static inline void EndTimer(bool ShowProgBar) {
EndTime = std::chrono::system_clock::now();
Duration =
std::chrono::duration_cast<std::chrono::seconds>(EndTime - StartTime);
if (ShowProgBar)
outs() << '\n';
else
outs() << Duration.count() << "s\n";
}
// -------------------------------------------------------------------------- //
// Main function
// -------------------------------------------------------------------------- //
int main(int argc, char *argv[]) {
WeightsMap Weights;
ProgressBar ProgBar;
std::error_code EC;
// ------------------------------------------------------------------------ //
// Parse command-line options
//
// Also check the target arguments, as this determines how we run afl-showmap.
// ------------------------------------------------------------------------ //
cl::ParseCommandLineOptions(argc, argv, "Optimal corpus minimizer");
if (!sys::fs::is_directory(OutputDir)) {
ErrMsg() << "Invalid output directory `" << OutputDir << "`\n";
return 1;
}
for (const auto &Arg : TargetArgs)
if (Arg == "@@") TargetArgsHasAtAt = true;
// ------------------------------------------------------------------------ //
// Find afl-showmap
// ------------------------------------------------------------------------ //
const auto AFLShowmapOrErr = sys::findProgramByName("afl-showmap");
if (AFLShowmapOrErr.getError()) {
ErrMsg() << "Failed to find afl-showmap. Check your PATH\n";
return 1;
}
AFLShowmapPath = *AFLShowmapOrErr;
// ------------------------------------------------------------------------ //
// Parse weights
//
// Weights are stored in CSV file mapping a seed file name to an integer
// greater than zero.
// ------------------------------------------------------------------------ //
if (WeightsFile != "") {
StatMsg() << "Reading weights from `" << WeightsFile << "`... ";
StartTimer(/*ShowProgBar=*/false);
const auto WeightsOrErr = MemoryBuffer::getFile(WeightsFile);
if (EC = WeightsOrErr.getError()) {
ErrMsg() << "Failed to read weights from `" << WeightsFile
<< "`: " << EC.message() << '\n';
return 1;
}
GetWeights(*WeightsOrErr.get(), Weights);
EndTimer(/*ShowProgBar=*/false);
}
// ------------------------------------------------------------------------ //
// Traverse corpus directory
//
// Find the seed files inside this directory.
// ------------------------------------------------------------------------ //
StatMsg() << "Locating seeds in `" << CorpusDir << "`... ";
StartTimer(/*ShowProgBar=*/false);
std::vector<std::string> SeedFiles;
sys::fs::file_status Status;
for (sys::fs::directory_iterator Dir(CorpusDir, EC), DirEnd;
Dir != DirEnd && !EC; Dir.increment(EC)) {
if (EC) {
ErrMsg() << "Failed to traverse corpus directory `" << CorpusDir
<< "`: " << EC.message() << '\n';
return 1;
}
const auto &Path = Dir->path();
if (EC = sys::fs::status(Path, Status)) {
WarnMsg() << "Failed to access seed file `" << Path
<< "`: " << EC.message() << ". Skipping...\n";
continue;
}
switch (Status.type()) {
case sys::fs::file_type::regular_file:
case sys::fs::file_type::symlink_file:
case sys::fs::file_type::type_unknown:
SeedFiles.push_back(Path);
default:
/* Ignore */
break;
}
}
EndTimer(/*ShowProgBar=*/false);
// ------------------------------------------------------------------------ //
// Generate seed coverage
//
// Iterate over the corpus directory, which should contain seed files. Execute
// these seeds in the target program to generate coverage information, and
// then store this coverage information in the appropriate data structures.
// ------------------------------------------------------------------------ //
size_t SeedCount = 0;
const size_t NumSeeds = SeedFiles.size();
if (!ShowProgBar)
StatMsg() << "Generating coverage for " << NumSeeds << " seeds... ";
StartTimer(ShowProgBar);
EvalMaxSAT Solver(/*nbMinimizeThread=*/0);
MaxSATSeeds SeedVars;
MaxSATCoverageMap SeedCoverage;
AFLCoverageVector Cov;
for (const auto &SeedFile : SeedFiles) {
// Execute seed
Cov.clear();
if (EC = getAFLCoverage(SeedFile, Cov)) {
ErrMsg() << "Failed to get coverage for seed " << SeedFile << ": "
<< EC.message() << '\n';
return 1;
}
// Create a variable to represent the seed
const SeedID Var = Solver.newVar();
SeedVars.push_back({Var, SeedFile});
// Record the set of seeds that cover a particular edge
for (const auto &[Edge, Freq] : Cov) {
if (EdgesOnly) {
// Ignore edge frequency
SeedCoverage[Edge].insert(Var);
} else {
// Executing edge `E` `N` times means that it was executed `N - 1` times
for (unsigned I = 0; I < Freq; ++I)
SeedCoverage[MAX_EDGE_FREQ * Edge + I].insert(Var);
}
}
if ((++SeedCount % 10 == 0) && ShowProgBar)
ProgBar.update(SeedCount * 100 / NumSeeds, "Generating seed coverage");
}
EndTimer(ShowProgBar);
// ------------------------------------------------------------------------ //
// Set the hard and soft constraints in the solver
// ------------------------------------------------------------------------ //
if (!ShowProgBar) StatMsg() << "Generating constraints... ";
StartTimer(ShowProgBar);
SeedCount = 0;
// Ensure that at least one seed is selected that covers a particular edge
// (hard constraint)
std::vector<SeedID> Clauses;
for (const auto &[_, Seeds] : SeedCoverage) {
if (Seeds.empty()) continue;
Clauses.clear();
for (const auto &Seed : Seeds)
Clauses.push_back(Seed);
Solver.addClause(Clauses);
if ((++SeedCount % 10 == 0) && ShowProgBar)
ProgBar.update(SeedCount * 100 / SeedCoverage.size(),
"Generating clauses");
}
// Select the minimum number of seeds that cover a particular set of edges
// (soft constraint)
for (const auto &[Var, Seed] : SeedVars)
Solver.addWeightedClause({-Var}, Weights[sys::path::filename(Seed)]);
EndTimer(ShowProgBar);
// ------------------------------------------------------------------------ //
// Generate a solution
// ------------------------------------------------------------------------ //
StatMsg() << "Solving... ";
StartTimer(/*ShowProgBar=*/false);
const bool Solved = Solver.solve();
EndTimer(/*ShowProgBar=*/false);
// ------------------------------------------------------------------------ //
// Save the solution
//
// This will copy the selected seeds to the given output directory.
// ------------------------------------------------------------------------ //
SmallVector<StringRef, 64> Solution;
SmallString<32> OutputSeed;
if (Solved) {
for (const auto &[Var, Seed] : SeedVars)
if (Solver.getValue(Var) > 0) Solution.push_back(Seed);
} else {
ErrMsg() << "Failed to find an optimal solution for `" << CorpusDir
<< "`\n";
return 1;
}
SuccMsg() << "Minimized corpus size: " << Solution.size() << " seeds\n";
if (!ShowProgBar) StatMsg() << "Copying to `" << OutputDir << "`... ";
StartTimer(ShowProgBar);
SeedCount = 0;
for (const auto &Seed : Solution) {
OutputSeed = OutputDir;
sys::path::append(OutputSeed, sys::path::filename(Seed));
if (EC = sys::fs::copy_file(Seed, OutputSeed)) {
WarnMsg() << "Failed to copy `" << Seed << "` to `" << OutputDir
<< "`: " << EC.message() << '\n';
}
if ((++SeedCount % 10 == 0) && ShowProgBar)
ProgBar.update(SeedCount * 100 / Solution.size(), "Copying seeds");
}
EndTimer(ShowProgBar);
SuccMsg() << "Done!\n";
return 0;
}
