afl-dyninst.cpp

#include <cstdlib>
#include <iostream>
#include <vector>
#include <string>
#include <stdlib.h>
#include <sstream>
#include <climits>
using namespace std;

// Command line parsing
#include <getopt.h>

// DyninstAPI includes
#include "BPatch.h"
#include "BPatch_binaryEdit.h"
#include "BPatch_flowGraph.h"
#include "BPatch_function.h"
#include "BPatch_point.h"

using namespace Dyninst;

//cmd line options
char *originalBinary;
char *instrumentedBinary;
bool verbose = false;
Dyninst::Address entryPoint;
set<string> instrumentLibraries;
set<string> runtimeLibraries;
int bbSkip = 0;
bool skipMainModule = false;

const char *instLibrary = "./libAflDyninst.so";

static const char *OPT_STR = "i:o:l:e:vs:dr:";
static const char *USAGE = " -i <binary> -o <binary> -l <library> -e <address> -s <number>\n \
            -i: Input binary \n \
            -o: Output binary\n \
            -d: Don't instrument the binary, only supplied libraries\n \
            -l: Linked library to instrument (repeat for more than one)\n \
            -r: Runtime library to instrument (path to, repeat for more than one)\n \
            -e: Entry point address to patch (required for stripped binaries)\n \
            -s: Number of basic blocks to skip\n \
            -v: Verbose output\n";

bool parseOptions(int argc, char **argv)
{

    int c;
    while ((c = getopt (argc, argv, OPT_STR)) != -1) {
        switch ((char) c) {
        case 'e':
            entryPoint = strtoul(optarg, NULL, 16);;
            break;
        case 'i':
            originalBinary = optarg;
            instrumentLibraries.insert(optarg);
            break;
        case 'o':
            instrumentedBinary = optarg;
            break;
        case 'l':
            instrumentLibraries.insert(optarg);
            break;
        case 'r':
            runtimeLibraries.insert(optarg);
            break;
        case 's':
            bbSkip = atoi(optarg);
            break;
        case 'd':
            skipMainModule = true;
            break;
        case 'v':
            verbose = true;
            break;
        default:
            cerr << "Usage: " << argv[0] << USAGE;
            return false;
        }
    }

    if(originalBinary == NULL) {
        cerr << "Input binary is required!"<< endl;
        cerr << "Usage: " << argv[0] << USAGE;
        return false;
    }

    if(instrumentedBinary == NULL) {
        cerr << "Output binary is required!" << endl;
        cerr << "Usage: " << argv[0] << USAGE;
        return false;
    }

    if(skipMainModule && instrumentLibraries.empty()) {
        cerr << "If using option -d , option -l is required." << endl;
        cerr << "Usage: " << argv[0] << USAGE;
        return false;
    }

    return true;
}

BPatch_function *findFuncByName (BPatch_image * appImage, char *funcName)
{
    BPatch_Vector < BPatch_function * >funcs;

    if (NULL == appImage->findFunction (funcName, funcs) || !funcs.size ()
        || NULL == funcs[0]) {
        cerr << "Failed to find " << funcName << " function." << endl;
        return NULL;
    }

    return funcs[0];
}

// insert callback to initialization function in the instrumentation library
// either at _init or at manualy specified entry point.
bool insertCallToInit(BPatch_binaryEdit * appBin, BPatch_function * instIncFunc,BPatch_module * module, BPatch_function *funcInit)
{

    /* Find the instrumentation points */
    vector<BPatch_point *> points;
    vector < BPatch_point * >*funcEntry = funcInit->findPoint (BPatch_entry);

    // rar main @ 0x4034c0
    // readpng main @ 0x400e0b

    if (NULL == funcEntry) {
        cerr << "Failed to find entry for function. " <<  endl;
        return false;
    }

    cout << "Inserting init callback." << endl;
    BPatch_Vector < BPatch_snippet * >instArgs; // init has no args
    BPatch_funcCallExpr instIncExpr (*instIncFunc, instArgs);

    /* Insert the snippet at function entry */
    BPatchSnippetHandle *handle =
        appBin->insertSnippet (instIncExpr, *funcEntry, BPatch_callBefore,
                               BPatch_lastSnippet);
    if (!handle) {
        cerr << "Failed to insert init callback." << endl;
        return false;
    }
    return true;
}

// inserts a callback for each basic block assigning it an instrumentation
// time 16bit random ID just as afl
bool insertBBCallback(BPatch_binaryEdit * appBin, BPatch_function * curFunc,
                      char *funcName, BPatch_function * instBBIncFunc,int *bbIndex)
{

    BPatch_flowGraph *appCFG = curFunc->getCFG ();
    unsigned short randID;

    if (!appCFG) {
        cerr << "Failed to find CFG for function " << funcName << endl;
        return false;
    }

    BPatch_Set < BPatch_basicBlock * >allBlocks;
    if (!appCFG->getAllBasicBlocks (allBlocks)) {
        cerr << "Failed to find basic blocks for function " << funcName << endl;
        return false;
    } else if (allBlocks.size () == 0) {
        cerr << "No basic blocks for function " << funcName << endl;
        return false;
    }

    BPatch_Set < BPatch_basicBlock * >::iterator iter;
    for (iter = allBlocks.begin (); iter != allBlocks.end (); iter++) {
        if(*bbIndex < bbSkip) { // skip over first bbSkip bbs
            (*bbIndex)++;
            continue;

        }
        unsigned long address = (*iter)->getStartAddress ();
        randID = rand() % USHRT_MAX;
        if(verbose) {
            cout << "Instrumenting Basic Block 0x" << hex << address << " of " <<
                 funcName << " with random id " << randID << endl;
        }

        BPatch_Vector < BPatch_snippet * >instArgs;
        BPatch_constExpr bbId (randID);
        instArgs.push_back (&bbId);
        BPatch_point *bbEntry = (*iter)->findEntryPoint ();
        if (NULL == bbEntry) {
            // warn the user, but continue
            cerr << "Failed to find entry for basic block at 0x" << hex << address
                 << endl;
            (*bbIndex)++;
            continue;
        }
        BPatch_funcCallExpr instIncExpr (*instBBIncFunc, instArgs);
        BPatchSnippetHandle *handle =
            appBin->insertSnippet (instIncExpr, *bbEntry, BPatch_callBefore,
                                   BPatch_lastSnippet);
        if (!handle) {
            // warn the user, but continue to next bb
            cerr << "Failed to insert instrumention in basic block at 0x" << hex <<
                 address << endl;
            (*bbIndex)++;
            continue;
        }

        (*bbIndex)++;
    }

    return true;

}

int main (int argc, char **argv)
{

    if(!parseOptions(argc,argv)) {
        return EXIT_FAILURE;
    }

    BPatch bpatch;

    BPatch_binaryEdit *appBin = bpatch.openBinary (originalBinary, !instrumentLibraries.empty());
    if (appBin == NULL) {
        cerr << "Failed to open binary" << endl;
        return EXIT_FAILURE;
    }

    if (!appBin->loadLibrary (instLibrary)) {
        cerr << "Failed to open instrumentation library." << endl;
        cerr << "It needs to be located in the current working directory." << endl;
        return EXIT_FAILURE;
    }

    BPatch_image *appImage = appBin->getImage ();

    /* Find code coverage functions in the instrumentation library */
    BPatch_function *initAflForkServer =
        findFuncByName (appImage, (char *) "initAflForkServer");
    BPatch_function *bbCallback =
        findFuncByName (appImage, (char *) "bbCallback");
    if (!initAflForkServer || !bbCallback ) {
        cerr << "Instrumentation library lacks callbacks!" << endl;
        return EXIT_FAILURE;
    }

    //get and iterate over all modules, instrumenting only the default and manualy specified ones
    vector < BPatch_module * >*modules = appImage->getModules ();
    vector < BPatch_module * >::iterator moduleIter;
    BPatch_module *defaultModule = NULL;
    string defaultModuleName;
    for (moduleIter = modules->begin (); moduleIter != modules->end (); ++moduleIter) {
    //find default module name
        char moduleName[1024];
        (*moduleIter)->getName (moduleName, 1024);    
        if (string (moduleName).find ("DEFAULT_MODULE") != string::npos) {
            defaultModuleName = "DEFAULT_MODULE";
        }
    }
    if(defaultModuleName.empty()) 
        defaultModuleName = string(originalBinary).substr(string(originalBinary).find_last_of("\\/")+1);
    int bbIndex = 0;
    for (moduleIter = modules->begin (); moduleIter != modules->end (); ++moduleIter) {
        char moduleName[1024];
        (*moduleIter)->getName (moduleName, 1024);

        if ((*moduleIter)->isSharedLib ()) {
            if (instrumentLibraries.find (moduleName) == instrumentLibraries.end ()) {
                cout << "Skipping library: " << moduleName << endl;
                continue;
            }
        }

        if (string (moduleName).find (defaultModuleName) != string::npos) {
            defaultModule = (*moduleIter);
            if(skipMainModule) continue;
        }
        cout << "Instrumenting module: " << moduleName << endl;
        vector < BPatch_function * >*allFunctions =
            (*moduleIter)->getProcedures ();
        vector < BPatch_function * >::iterator funcIter;

        // iterate over all functions in the module
        for (funcIter = allFunctions->begin (); funcIter != allFunctions->end ();
             ++funcIter) {
            BPatch_function *curFunc = *funcIter;
            char funcName[1024];
            curFunc->getName (funcName, 1024);
            if(string (funcName) == string("_start")) continue; // here's a bug on hlt
            insertBBCallback (appBin, curFunc, funcName, bbCallback, &bbIndex);
        }

    }

    //if entrypoint set ,find function  , else find _init
    BPatch_function *funcToPatch = NULL;
    if(!entryPoint) {
        BPatch_Vector<BPatch_function*> funcs;
        defaultModule->findFunction("_init", funcs);
        if(!funcs.size()) {
            cerr << "Couldn't locate _init, specify entry point manualy. "<< endl;
            return EXIT_FAILURE;
        }
        // there should really be only one
        funcToPatch = funcs[0];
    } else {
        funcToPatch = defaultModule->findFunctionByEntry(entryPoint);
    }
    if(!funcToPatch) {
        cerr << "Couldn't locate function at given entry point. "<< endl;
        return EXIT_FAILURE;
    }
    if(!insertCallToInit (appBin,  initAflForkServer,defaultModule,funcToPatch)){
        cerr << "Could not insert init callback at given entry point." << endl;
        return EXIT_FAILURE;
    }

    cout << "Saving the instrumented binary to " << instrumentedBinary << "..." << endl;
    // Output the instrumented binary
    if (!appBin->writeFile (instrumentedBinary)) {
        cerr << "Failed to write output file: " << instrumentedBinary << endl;
        return EXIT_FAILURE;
    }

    if(!runtimeLibraries.empty()) {
        cout << "Instrumenting runtime libraries." << endl;
        set<string>::iterator rtLibIter ;
        for(rtLibIter = runtimeLibraries.begin(); rtLibIter != runtimeLibraries.end(); rtLibIter++) {
            BPatch_binaryEdit *libBin = bpatch.openBinary ((*rtLibIter).c_str(), false);
            if (libBin == NULL) {
                cerr << "Failed to open binary "<< *rtLibIter << endl;
                return EXIT_FAILURE;
            }
            libBin->loadLibrary (instLibrary);
            BPatch_image *libImg = libBin->getImage ();
            vector < BPatch_module * >*modules = libImg->getModules ();
            moduleIter = modules->begin ();
            ++moduleIter;
            for ( ; moduleIter != modules->end (); ++moduleIter) {
                char moduleName[1024];
                (*moduleIter)->getName (moduleName, 1024);
                cout << "Instrumenting module: " << moduleName << endl;
                vector < BPatch_function * >*allFunctions =
                    (*moduleIter)->getProcedures ();
                vector < BPatch_function * >::iterator funcIter;
                // iterate over all functions in the module
                for (funcIter = allFunctions->begin (); funcIter != allFunctions->end ();
                     ++funcIter) {
                    BPatch_function *curFunc = *funcIter;
                    char funcName[1024];
                    curFunc->getName (funcName, 1024);
                    if(string (funcName) == string("_start")) continue;
                    insertBBCallback (libBin, curFunc, funcName, bbCallback, &bbIndex);
                }
            }
            if (!libBin->writeFile ((*rtLibIter + ".ins").c_str())) {
                cerr << "Failed to write output file: " <<(*rtLibIter + ".ins").c_str() << endl;
                return EXIT_FAILURE;
            } else {
                cout << "Saved the instrumented library to " << (*rtLibIter + ".ins").c_str() << "." << endl;
            }
        }
    }

    cout << "All done! Happy fuzzing!" << endl;
    return EXIT_SUCCESS;

}