fuzz.c

/*
 *
 * honggfuzz - fuzzing routines
 * -----------------------------------------
 *
 * Authors: Robert Swiecki <swiecki@google.com>
 *          Felix Gröbert <groebert@google.com>
 *
 * Copyright 2010-2018 by 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
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * permissions and limitations under the License.
 *
 */

#include "fuzz.h"

#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <libgen.h>
#include <pthread.h>
#include <signal.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>

#include "arch.h"
#include "honggfuzz.h"
#include "input.h"
#include "libhfcommon/common.h"
#include "libhfcommon/files.h"
#include "libhfcommon/log.h"
#include "libhfcommon/util.h"
#include "mangle.h"
#include "report.h"
#include "sanitizers.h"
#include "socketfuzzer.h"
#include "subproc.h"

static time_t termTimeStamp = 0;

bool fuzz_isTerminating(void) {
    if (ATOMIC_GET(termTimeStamp) != 0) {
        return true;
    }
    return false;
}

void fuzz_setTerminating(void) {
    if (ATOMIC_GET(termTimeStamp) != 0) {
        return;
    }
    ATOMIC_SET(termTimeStamp, time(NULL));
}

bool fuzz_shouldTerminate() {
    if (ATOMIC_GET(termTimeStamp) == 0) {
        return false;
    }
    if ((time(NULL) - ATOMIC_GET(termTimeStamp)) > 5) {
        return true;
    }
    return false;
}

static fuzzState_t fuzz_getState(honggfuzz_t* hfuzz) {
    return ATOMIC_GET(hfuzz->feedback.state);
}

static bool fuzz_writeCovFile(const char* dir, const uint8_t* data, size_t len) {
    char fname[PATH_MAX];

    uint64_t crc64f = util_CRC64(data, len);
    uint64_t crc64r = util_CRC64Rev(data, len);
    snprintf(fname, sizeof(fname), "%s/%016" PRIx64 "%016" PRIx64 ".%08" PRIx32 ".honggfuzz.cov",
        dir, crc64f, crc64r, (uint32_t)len);

    if (files_exists(fname)) {
        LOG_D("File '%s' already exists in the output corpus directory '%s'", fname, dir);
        return true;
    }

    LOG_D("Adding file '%s' to the corpus directory '%s'", fname, dir);

    if (!files_writeBufToFile(fname, data, len, O_WRONLY | O_CREAT | O_EXCL | O_CLOEXEC)) {
        LOG_W("Couldn't write buffer to file '%s'", fname);
        return false;
    }

    return true;
}

static void fuzz_addFileToFileQ(honggfuzz_t* hfuzz, const uint8_t* data, size_t len) {
    ATOMIC_SET(hfuzz->timing.lastCovUpdate, time(NULL));

    struct dynfile_t* dynfile = (struct dynfile_t*)util_Malloc(sizeof(struct dynfile_t));
    dynfile->size = len;
    dynfile->data = (uint8_t*)util_Malloc(len);
    memcpy(dynfile->data, data, len);

    MX_SCOPED_RWLOCK_WRITE(&hfuzz->io.dynfileq_mutex);
    TAILQ_INSERT_TAIL(&hfuzz->io.dynfileq, dynfile, pointers);
    hfuzz->io.dynfileqCnt++;

    if (hfuzz->socketFuzzer.enabled) {
        /* Don't add coverage data to files in socketFuzzer mode */
        return;
    }

    if (!fuzz_writeCovFile(hfuzz->io.covDirAll, data, len)) {
        LOG_E("Couldn't save the coverage data to '%s'", hfuzz->io.covDirAll);
    }

    /* No need to add files to the new coverage dir, if this is just the dry-run phase */
    if (fuzz_getState(hfuzz) == _HF_STATE_DYNAMIC_DRY_RUN || hfuzz->io.covDirNew == NULL) {
        return;
    }

    if (!fuzz_writeCovFile(hfuzz->io.covDirNew, data, len)) {
        LOG_E("Couldn't save the new coverage data to '%s'", hfuzz->io.covDirNew);
    }
}

static void fuzz_setDynamicMainState(run_t* run) {
    /* All threads need to indicate willingness to switch to the DYNAMIC_MAIN state. Count them! */
    static uint32_t cnt = 0;
    ATOMIC_PRE_INC(cnt);

    static pthread_mutex_t state_mutex = PTHREAD_MUTEX_INITIALIZER;
    MX_SCOPED_LOCK(&state_mutex);

    if (fuzz_getState(run->global) == _HF_STATE_DYNAMIC_MAIN) {
        return;
    }

    for (;;) {
        /* Check if all threads have already reported in for changing state */
        if (ATOMIC_GET(cnt) == run->global->threads.threadsMax) {
            break;
        }
        if (fuzz_isTerminating()) {
            return;
        }
        usleep(1000 * 10); /* Check every 10ms */
    }

    LOG_I("Entering phase 2/2: Dynamic Main");
    snprintf(run->origFileName, sizeof(run->origFileName), "[DYNAMIC]");
    ATOMIC_SET(run->global->feedback.state, _HF_STATE_DYNAMIC_MAIN);

    /*
     * If the initial fuzzing yielded no useful coverage, just add a single 1-byte file to the
     * dynamic corpus, so the dynamic phase doesn't fail because of lack of useful inputs
     */
    if (run->global->io.dynfileqCnt == 0) {
        const char* single_byte = run->global->cfg.only_printable ? " " : "\0";
        fuzz_addFileToFileQ(run->global, (const uint8_t*)single_byte, 1U);
    }
}

static void fuzz_perfFeedback(run_t* run) {
    if (run->global->feedback.skipFeedbackOnTimeout && run->tmOutSignaled) {
        return;
    }

    LOG_D("New file size: %zu, Perf feedback new/cur (instr,branch): %" PRIu64 "/%" PRIu64
          "/%" PRIu64 "/%" PRIu64 ", BBcnt new/total: %" PRIu64 "/%" PRIu64,
        run->dynamicFileSz, run->linux.hwCnts.cpuInstrCnt, run->global->linux.hwCnts.cpuInstrCnt,
        run->linux.hwCnts.cpuBranchCnt, run->global->linux.hwCnts.cpuBranchCnt,
        run->linux.hwCnts.newBBCnt, run->global->linux.hwCnts.bbCnt);

    MX_SCOPED_LOCK(&run->global->feedback.feedback_mutex);

    uint64_t softCntPc = 0;
    uint64_t softCntEdge = 0;
    uint64_t softCntCmp = 0;
    if (run->global->feedback.bbFd != -1) {
        softCntPc = ATOMIC_GET(run->global->feedback.feedbackMap->pidFeedbackPc[run->fuzzNo]);
        ATOMIC_CLEAR(run->global->feedback.feedbackMap->pidFeedbackPc[run->fuzzNo]);
        softCntEdge = ATOMIC_GET(run->global->feedback.feedbackMap->pidFeedbackEdge[run->fuzzNo]);
        ATOMIC_CLEAR(run->global->feedback.feedbackMap->pidFeedbackEdge[run->fuzzNo]);
        softCntCmp = ATOMIC_GET(run->global->feedback.feedbackMap->pidFeedbackCmp[run->fuzzNo]);
        ATOMIC_CLEAR(run->global->feedback.feedbackMap->pidFeedbackCmp[run->fuzzNo]);
    }

    int64_t diff0 = run->global->linux.hwCnts.cpuInstrCnt - run->linux.hwCnts.cpuInstrCnt;
    int64_t diff1 = run->global->linux.hwCnts.cpuBranchCnt - run->linux.hwCnts.cpuBranchCnt;

    /* Any increase in coverage (edge, pc, cmp, hw) counters forces adding input to the corpus */
    if (run->linux.hwCnts.newBBCnt > 0 || softCntPc > 0 || softCntEdge > 0 || softCntCmp > 0 ||
        diff0 < 0 || diff1 < 0) {
        if (diff0 < 0) {
            run->global->linux.hwCnts.cpuInstrCnt = run->linux.hwCnts.cpuInstrCnt;
        }
        if (diff1 < 0) {
            run->global->linux.hwCnts.cpuBranchCnt = run->linux.hwCnts.cpuBranchCnt;
        }
        run->global->linux.hwCnts.bbCnt += run->linux.hwCnts.newBBCnt;
        run->global->linux.hwCnts.softCntPc += softCntPc;
        run->global->linux.hwCnts.softCntEdge += softCntEdge;
        run->global->linux.hwCnts.softCntCmp += softCntCmp;

        LOG_I("Size:%zu (i,b,hw,edge,ip,cmp): %" PRIu64 "/%" PRIu64 "/%" PRIu64 "/%" PRIu64
              "/%" PRIu64 "/%" PRIu64 ", Tot:%" PRIu64 "/%" PRIu64 "/%" PRIu64 "/%" PRIu64
              "/%" PRIu64 "/%" PRIu64,
            run->dynamicFileSz, run->linux.hwCnts.cpuInstrCnt, run->linux.hwCnts.cpuBranchCnt,
            run->linux.hwCnts.newBBCnt, softCntEdge, softCntPc, softCntCmp,
            run->global->linux.hwCnts.cpuInstrCnt, run->global->linux.hwCnts.cpuBranchCnt,
            run->global->linux.hwCnts.bbCnt, run->global->linux.hwCnts.softCntEdge,
            run->global->linux.hwCnts.softCntPc, run->global->linux.hwCnts.softCntCmp);

        fuzz_addFileToFileQ(run->global, run->dynamicFile, run->dynamicFileSz);

        if (run->global->socketFuzzer.enabled) {
            LOG_D("SocketFuzzer: fuzz: new BB (perf)");
            fuzz_notifySocketFuzzerNewCov(run->global);
        }
    }
}

/* Return value indicates whether report file should be updated with the current verified crash */
static bool fuzz_runVerifier(run_t* run) {
    if (!run->crashFileName[0] || !run->backtrace) {
        return false;
    }

    uint64_t backtrace = run->backtrace;

    char origCrashPath[PATH_MAX];
    snprintf(origCrashPath, sizeof(origCrashPath), "%s", run->crashFileName);
    /* Workspace is inherited, just append a extra suffix */
    char verFile[PATH_MAX];
    snprintf(verFile, sizeof(verFile), "%s.verified", origCrashPath);

    if (files_exists(verFile)) {
        LOG_D("Crash file to verify '%s' is already verified as '%s'", origCrashPath, verFile);
        return false;
    }

    for (int i = 0; i < _HF_VERIFIER_ITER; i++) {
        LOG_I("Launching verifier for HASH: %" PRIx64 " (iteration: %d out of %d)", run->backtrace,
            i + 1, _HF_VERIFIER_ITER);
        run->timeStartedMillis = 0;
        run->backtrace = 0;
        run->access = 0;
        run->exception = 0;
        run->mainWorker = false;

        if (!subproc_Run(run)) {
            LOG_F("subproc_Run()");
        }

        /* If stack hash doesn't match skip name tag and exit */
        if (run->backtrace != backtrace) {
            LOG_E("Verifier stack mismatch: (original) %" PRIx64 " != (new) %" PRIx64, backtrace,
                run->backtrace);
            run->backtrace = backtrace;
            return true;
        }

        LOG_I("Verifier for HASH: %" PRIx64 " (iteration: %d, left: %d). MATCH!", run->backtrace,
            i + 1, _HF_VERIFIER_ITER - i - 1);
    }

    /* Copy file with new suffix & remove original copy */
    int fd = TEMP_FAILURE_RETRY(open(verFile, O_CREAT | O_EXCL | O_WRONLY, 0600));
    if (fd == -1 && errno == EEXIST) {
        LOG_I("It seems that '%s' already exists, skipping", verFile);
        return false;
    }
    if (fd == -1) {
        PLOG_E("Couldn't create '%s'", verFile);
        return true;
    }
    defer {
        close(fd);
    };
    if (!files_writeToFd(fd, run->dynamicFile, run->dynamicFileSz)) {
        LOG_E("Couldn't save verified file as '%s'", verFile);
        unlink(verFile);
        return true;
    }

    LOG_I("Verified crash for HASH: %" PRIx64 " and saved it as '%s'", backtrace, verFile);
    ATOMIC_PRE_INC(run->global->cnts.verifiedCrashesCnt);

    return true;
}

static bool fuzz_fetchInput(run_t* run) {
    if (fuzz_getState(run->global) == _HF_STATE_DYNAMIC_DRY_RUN) {
        run->mutationsPerRun = 0U;
        if (input_prepareStaticFile(run, /* rewind= */ false)) {
            return true;
        }
        fuzz_setDynamicMainState(run);
        run->mutationsPerRun = run->global->mutate.mutationsPerRun;
    }

    if (fuzz_getState(run->global) == _HF_STATE_DYNAMIC_MAIN) {
        if (run->global->exe.externalCommand) {
            if (!input_prepareExternalFile(run)) {
                LOG_E("input_prepareFileExternally() failed");
                return false;
            }
        } else if (!input_prepareDynamicInput(run)) {
            LOG_E("input_prepareFileDynamically() failed");
            return false;
        }
    }

    if (fuzz_getState(run->global) == _HF_STATE_STATIC) {
        if (run->global->exe.externalCommand) {
            if (!input_prepareExternalFile(run)) {
                LOG_E("input_prepareFileExternally() failed");
                return false;
            }
        } else if (!input_prepareStaticFile(run, true /* rewind */)) {
            LOG_E("input_prepareFile() failed");
            return false;
        }
    }

    if (run->global->exe.postExternalCommand && !input_postProcessFile(run)) {
        LOG_E("input_postProcessFile() failed");
        return false;
    }

    return true;
}

static void fuzz_fuzzLoop(run_t* run) {
    run->timeStartedMillis = 0;
    run->crashFileName[0] = '\0';
    run->pc = 0;
    run->backtrace = 0;
    run->access = 0;
    run->exception = 0;
    run->report[0] = '\0';
    run->mainWorker = true;
    run->mutationsPerRun = run->global->mutate.mutationsPerRun;
    run->dynamicFileSz = 0;
    run->dynamicFileCopyFd = -1;
    run->tmOutSignaled = false;

    run->linux.hwCnts.cpuInstrCnt = 0;
    run->linux.hwCnts.cpuBranchCnt = 0;
    run->linux.hwCnts.bbCnt = 0;
    run->linux.hwCnts.newBBCnt = 0;

    if (!fuzz_fetchInput(run)) {
        LOG_F("Cound't prepare input for fuzzing");
    }
    if (!subproc_Run(run)) {
        LOG_F("Couldn't run fuzzed command");
    }

    if (run->global->feedback.dynFileMethod != _HF_DYNFILE_NONE) {
        fuzz_perfFeedback(run);
    }
    if (run->global->cfg.useVerifier && !fuzz_runVerifier(run)) {
        return;
    }
    report_Report(run);
}

static void fuzz_fuzzLoopSocket(run_t* run) {
    run->pid = 0;
    run->timeStartedMillis = 0;
    run->crashFileName[0] = '\0';
    run->pc = 0;
    run->backtrace = 0;
    run->access = 0;
    run->exception = 0;
    run->report[0] = '\0';
    run->mainWorker = true;
    run->mutationsPerRun = run->global->mutate.mutationsPerRun;
    run->dynamicFileSz = 0;
    run->dynamicFileCopyFd = -1;
    run->tmOutSignaled = false;

    run->linux.hwCnts.cpuInstrCnt = 0;
    run->linux.hwCnts.cpuBranchCnt = 0;
    run->linux.hwCnts.bbCnt = 0;
    run->linux.hwCnts.newBBCnt = 0;

    LOG_I("------------------------------------------------------");

    /* First iteration: Start target
       Other iterations: re-start target, if necessary
       subproc_Run() will decide by itself if a restart is necessary, via
       subproc_New()
    */
    LOG_D("------[ 1: subproc_run");
    if (!subproc_Run(run)) {
        LOG_W("Couldn't run server");
    }

    /* Tell the external fuzzer to send data to target
       The fuzzer will notify us when finished; block until then.
    */
    LOG_D("------[ 2: fetch input");
    if (!fuzz_waitForExternalInput(run)) {
        /* Fuzzer could not connect to target, and told us to
           restart it. Do it on the next iteration. */
        LOG_D("------[ 2.1: Target down, will restart it");
        return;
    }

    LOG_D("------[ 3: feedback");
    if (run->global->feedback.dynFileMethod != _HF_DYNFILE_NONE) {
        fuzz_perfFeedback(run);
    }
    if (run->global->cfg.useVerifier && !fuzz_runVerifier(run)) {
        return;
    }

    report_Report(run);
}

static void* fuzz_threadNew(void* arg) {
    honggfuzz_t* hfuzz = (honggfuzz_t*)arg;
    unsigned int fuzzNo = ATOMIC_POST_INC(hfuzz->threads.threadsActiveCnt);
    LOG_I("Launched new fuzzing thread, no. #%" PRId32, fuzzNo);

    run_t run = {
        .global = hfuzz,
        .pid = 0,
        .dynfileqCurrent = NULL,
        .dynamicFile = NULL,
        .dynamicFileFd = -1,
        .fuzzNo = fuzzNo,
        .persistentSock = -1,
        .tmOutSignaled = false,
        .origFileName = "[DYNAMIC]",
    };

    /* Do not try to handle input files with socketfuzzer */
    if (!hfuzz->socketFuzzer.enabled) {
        if (!(run.dynamicFile = files_mapSharedMem(hfuzz->mutate.maxFileSz, &run.dynamicFileFd,
                  "hfuzz-input", run.global->io.workDir))) {
            LOG_F("Couldn't create an input file of size: %zu", hfuzz->mutate.maxFileSz);
        }
    }
    defer {
        if (run.dynamicFileFd != -1) {
            close(run.dynamicFileFd);
        }
    };

    if (!arch_archThreadInit(&run)) {
        LOG_F("Could not initialize the thread");
    }

    for (;;) {
        /* Check if dry run mode with verifier enabled */
        if (run.global->mutate.mutationsPerRun == 0U && run.global->cfg.useVerifier &&
            !hfuzz->socketFuzzer.enabled) {
            if (ATOMIC_POST_INC(run.global->cnts.mutationsCnt) >= run.global->io.fileCnt) {
                break;
            }
        }
        /* Check for max iterations limit if set */
        else if ((ATOMIC_POST_INC(run.global->cnts.mutationsCnt) >=
                     run.global->mutate.mutationsMax) &&
                 run.global->mutate.mutationsMax) {
            break;
        }

        input_setSize(&run, run.global->mutate.maxFileSz);
        if (hfuzz->socketFuzzer.enabled) {
            fuzz_fuzzLoopSocket(&run);
        } else {
            fuzz_fuzzLoop(&run);
        }

        if (fuzz_isTerminating()) {
            break;
        }

        if (run.global->cfg.exitUponCrash && ATOMIC_GET(run.global->cnts.crashesCnt) > 0) {
            LOG_I("Seen a crash. Terminating all fuzzing threads");
            fuzz_setTerminating();
            break;
        }
    }

    if (run.pid) {
        kill(run.pid, SIGKILL);
    }

    LOG_I("Terminating thread no. #%" PRId32 ", left: %zu", fuzzNo,
        hfuzz->threads.threadsMax - ATOMIC_GET(run.global->threads.threadsFinished));
    ATOMIC_POST_INC(run.global->threads.threadsFinished);
    return NULL;
}

void fuzz_threadsStart(honggfuzz_t* hfuzz) {
    if (!arch_archInit(hfuzz)) {
        LOG_F("Couldn't prepare arch for fuzzing");
    }
    if (!sanitizers_Init(hfuzz)) {
        LOG_F("Couldn't prepare sanitizer options");
    }

    if (hfuzz->socketFuzzer.enabled) {
        /* Don't do dry run with socketFuzzer */
        LOG_I("Entering phase - Feedback Driven Mode (SocketFuzzer)");
        hfuzz->feedback.state = _HF_STATE_DYNAMIC_MAIN;
    } else if (hfuzz->feedback.dynFileMethod != _HF_DYNFILE_NONE) {
        LOG_I("Entering phase 1/2: Dry Run");
        hfuzz->feedback.state = _HF_STATE_DYNAMIC_DRY_RUN;
    } else {
        LOG_I("Entering phase: Static");
        hfuzz->feedback.state = _HF_STATE_STATIC;
    }

    for (size_t i = 0; i < hfuzz->threads.threadsMax; i++) {
        if (!subproc_runThread(hfuzz, &hfuzz->threads.threads[i], fuzz_threadNew)) {
            PLOG_F("Couldn't run a thread #%zu", i);
        }
    }
}