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fuzzer.go
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fuzzer.go
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// Copyright 2015 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
package main
import (
"flag"
"fmt"
"net/http"
_ "net/http/pprof"
"os"
"runtime"
"runtime/debug"
"strconv"
"strings"
"sync"
"sync/atomic"
"syscall"
"time"
"github.com/google/syzkaller/pkg/hash"
"github.com/google/syzkaller/pkg/host"
"github.com/google/syzkaller/pkg/ipc"
. "github.com/google/syzkaller/pkg/log"
"github.com/google/syzkaller/pkg/osutil"
. "github.com/google/syzkaller/pkg/rpctype"
"github.com/google/syzkaller/pkg/signal"
"github.com/google/syzkaller/prog"
"github.com/google/syzkaller/sys"
)
type Fuzzer struct {
name string
outputType OutputType
config *ipc.Config
execOpts *ipc.ExecOpts
procs []*Proc
gate *ipc.Gate
workQueue *WorkQueue
needPoll chan struct{}
choiceTable *prog.ChoiceTable
stats [StatCount]uint64
manager *RPCClient
target *prog.Target
faultInjectionEnabled bool
comparisonTracingEnabled bool
coverageEnabled bool
leakCheckEnabled bool
leakCheckReady uint32
corpusMu sync.RWMutex
corpus []*prog.Prog
corpusHashes map[hash.Sig]struct{}
signalMu sync.RWMutex
corpusSignal signal.Signal // signal of inputs in corpus
maxSignal signal.Signal // max signal ever observed including flakes
newSignal signal.Signal // diff of maxSignal since last sync with master
logMu sync.Mutex
}
type Stat int
const (
StatGenerate Stat = iota
StatFuzz
StatCandidate
StatTriage
StatMinimize
StatSmash
StatHint
StatSeed
StatCount
)
var statNames = [StatCount]string{
StatGenerate: "exec gen",
StatFuzz: "exec fuzz",
StatCandidate: "exec candidate",
StatTriage: "exec triage",
StatMinimize: "exec minimize",
StatSmash: "exec smash",
StatHint: "exec hints",
StatSeed: "exec seeds",
}
type OutputType int
const (
OutputNone OutputType = iota
OutputStdout
OutputDmesg
OutputFile
)
func main() {
debug.SetGCPercent(50)
var (
flagName = flag.String("name", "test", "unique name for manager")
flagArch = flag.String("arch", runtime.GOARCH, "target arch")
flagManager = flag.String("manager", "", "manager rpc address")
flagProcs = flag.Int("procs", 1, "number of parallel test processes")
flagLeak = flag.Bool("leak", false, "detect memory leaks")
flagOutput = flag.String("output", "stdout", "write programs to none/stdout/dmesg/file")
flagPprof = flag.String("pprof", "", "address to serve pprof profiles")
flagTest = flag.Bool("test", false, "enable image testing mode") // used by syz-ci
)
flag.Parse()
var outputType OutputType
switch *flagOutput {
case "none":
outputType = OutputNone
case "stdout":
outputType = OutputStdout
case "dmesg":
outputType = OutputDmesg
case "file":
outputType = OutputFile
default:
fmt.Fprintf(os.Stderr, "-output flag must be one of none/stdout/dmesg/file\n")
os.Exit(1)
}
Logf(0, "fuzzer started")
target, err := prog.GetTarget(runtime.GOOS, *flagArch)
if err != nil {
Fatalf("%v", err)
}
config, execOpts, err := ipc.DefaultConfig()
if err != nil {
panic(err)
}
sandbox := "none"
if config.Flags&ipc.FlagSandboxSetuid != 0 {
sandbox = "setuid"
} else if config.Flags&ipc.FlagSandboxNamespace != 0 {
sandbox = "namespace"
}
shutdown := make(chan struct{})
osutil.HandleInterrupts(shutdown)
go func() {
// Handles graceful preemption on GCE.
<-shutdown
Logf(0, "SYZ-FUZZER: PREEMPTED")
os.Exit(1)
}()
if *flagTest {
testImage(*flagManager, target, sandbox)
return
}
if *flagPprof != "" {
go func() {
err := http.ListenAndServe(*flagPprof, nil)
Fatalf("failed to serve pprof profiles: %v", err)
}()
} else {
runtime.MemProfileRate = 0
}
Logf(0, "dialing manager at %v", *flagManager)
a := &ConnectArgs{*flagName}
r := &ConnectRes{}
if err := RPCCall(*flagManager, "Manager.Connect", a, r); err != nil {
panic(err)
}
calls := buildCallList(target, r.EnabledCalls, sandbox)
ct := target.BuildChoiceTable(r.Prios, calls)
// This requires "fault-inject: support systematic fault injection" kernel commit.
faultInjectionEnabled := false
if fd, err := syscall.Open("/proc/self/fail-nth", syscall.O_RDWR, 0); err == nil {
syscall.Close(fd)
faultInjectionEnabled = true
}
if calls[target.SyscallMap["syz_emit_ethernet"]] ||
calls[target.SyscallMap["syz_extract_tcp_res"]] {
config.Flags |= ipc.FlagEnableTun
}
if faultInjectionEnabled {
config.Flags |= ipc.FlagEnableFault
}
coverageEnabled := config.Flags&ipc.FlagSignal != 0
kcov, comparisonTracingEnabled := checkCompsSupported()
Logf(0, "kcov=%v, comps=%v", kcov, comparisonTracingEnabled)
if r.NeedCheck {
out, err := osutil.RunCmd(time.Minute, "", config.Executor, "version")
if err != nil {
panic(err)
}
vers := strings.Split(strings.TrimSpace(string(out)), " ")
if len(vers) != 4 {
panic(fmt.Sprintf("bad executor version: %q", string(out)))
}
a := &CheckArgs{
Name: *flagName,
UserNamespaces: osutil.IsExist("/proc/self/ns/user"),
FuzzerGitRev: sys.GitRevision,
FuzzerSyzRev: target.Revision,
ExecutorGitRev: vers[3],
ExecutorSyzRev: vers[2],
ExecutorArch: vers[1],
}
a.Kcov = kcov
if fd, err := syscall.Open("/sys/kernel/debug/kmemleak", syscall.O_RDWR, 0); err == nil {
syscall.Close(fd)
a.Leak = true
}
a.Fault = faultInjectionEnabled
a.CompsSupported = comparisonTracingEnabled
for c := range calls {
a.Calls = append(a.Calls, c.Name)
}
if err := RPCCall(*flagManager, "Manager.Check", a, nil); err != nil {
panic(err)
}
}
// Manager.Connect reply can ve very large and that memory will be permanently cached in the connection.
// So we do the call on a transient connection, free all memory and reconnect.
// The rest of rpc requests have bounded size.
debug.FreeOSMemory()
manager, err := NewRPCClient(*flagManager)
if err != nil {
panic(err)
}
kmemleakInit(*flagLeak)
needPoll := make(chan struct{}, 1)
needPoll <- struct{}{}
fuzzer := &Fuzzer{
name: *flagName,
outputType: outputType,
config: config,
execOpts: execOpts,
workQueue: newWorkQueue(*flagProcs, needPoll),
needPoll: needPoll,
choiceTable: ct,
manager: manager,
target: target,
faultInjectionEnabled: faultInjectionEnabled,
comparisonTracingEnabled: comparisonTracingEnabled,
coverageEnabled: coverageEnabled,
leakCheckEnabled: *flagLeak,
corpusHashes: make(map[hash.Sig]struct{}),
}
fuzzer.gate = ipc.NewGate(2**flagProcs, fuzzer.leakCheckCallback)
for _, inp := range r.Inputs {
fuzzer.addInputFromAnotherFuzzer(inp)
}
fuzzer.addMaxSignal(r.MaxSignal.Deserialize())
for _, candidate := range r.Candidates {
p, err := fuzzer.target.Deserialize(candidate.Prog)
if err != nil {
panic(err)
}
if coverageEnabled {
flags := ProgCandidate
if candidate.Minimized {
flags |= ProgMinimized
}
if candidate.Smashed {
flags |= ProgSmashed
}
fuzzer.workQueue.enqueue(&WorkCandidate{
p: p,
flags: flags,
})
} else {
fuzzer.addInputToCorpus(p, nil, hash.Hash(candidate.Prog))
}
}
for pid := 0; pid < *flagProcs; pid++ {
proc, err := newProc(fuzzer, pid)
if err != nil {
Fatalf("failed to create proc: %v", err)
}
fuzzer.procs = append(fuzzer.procs, proc)
go proc.loop()
}
fuzzer.pollLoop()
}
func (fuzzer *Fuzzer) pollLoop() {
var execTotal uint64
var lastPoll time.Time
var lastPrint time.Time
ticker := time.NewTicker(3 * time.Second).C
for {
poll := false
select {
case <-ticker:
case <-fuzzer.needPoll:
poll = true
}
if fuzzer.outputType != OutputStdout && time.Since(lastPrint) > 10*time.Second {
// Keep-alive for manager.
Logf(0, "alive, executed %v", execTotal)
lastPrint = time.Now()
}
if poll || time.Since(lastPoll) > 10*time.Second {
needCandidates := fuzzer.workQueue.wantCandidates()
if poll && !needCandidates {
continue
}
a := &PollArgs{
Name: fuzzer.name,
NeedCandidates: needCandidates,
Stats: make(map[string]uint64),
}
a.MaxSignal = fuzzer.grabNewSignal().Serialize()
for _, proc := range fuzzer.procs {
a.Stats["exec total"] += atomic.SwapUint64(&proc.env.StatExecs, 0)
a.Stats["executor restarts"] += atomic.SwapUint64(&proc.env.StatRestarts, 0)
}
for stat := Stat(0); stat < StatCount; stat++ {
v := atomic.SwapUint64(&fuzzer.stats[stat], 0)
a.Stats[statNames[stat]] = v
execTotal += v
}
r := &PollRes{}
if err := fuzzer.manager.Call("Manager.Poll", a, r); err != nil {
panic(err)
}
maxSignal := r.MaxSignal.Deserialize()
Logf(1, "poll: candidates=%v inputs=%v signal=%v",
len(r.Candidates), len(r.NewInputs), maxSignal.Len())
fuzzer.addMaxSignal(maxSignal)
for _, inp := range r.NewInputs {
fuzzer.addInputFromAnotherFuzzer(inp)
}
for _, candidate := range r.Candidates {
p, err := fuzzer.target.Deserialize(candidate.Prog)
if err != nil {
panic(err)
}
if fuzzer.coverageEnabled {
flags := ProgCandidate
if candidate.Minimized {
flags |= ProgMinimized
}
if candidate.Smashed {
flags |= ProgSmashed
}
fuzzer.workQueue.enqueue(&WorkCandidate{
p: p,
flags: flags,
})
} else {
fuzzer.addInputToCorpus(p, nil, hash.Hash(candidate.Prog))
}
}
if len(r.Candidates) == 0 && fuzzer.leakCheckEnabled &&
atomic.LoadUint32(&fuzzer.leakCheckReady) == 0 {
kmemleakScan(false) // ignore boot leaks
atomic.StoreUint32(&fuzzer.leakCheckReady, 1)
}
if len(r.NewInputs) == 0 && len(r.Candidates) == 0 {
lastPoll = time.Now()
}
}
}
}
func buildCallList(target *prog.Target, enabledCalls, sandbox string) map[*prog.Syscall]bool {
calls := make(map[*prog.Syscall]bool)
if enabledCalls != "" {
for _, id := range strings.Split(enabledCalls, ",") {
n, err := strconv.ParseUint(id, 10, 64)
if err != nil || n >= uint64(len(target.Syscalls)) {
panic(fmt.Sprintf("invalid syscall in -calls flag: %v", id))
}
calls[target.Syscalls[n]] = true
}
} else {
for _, c := range target.Syscalls {
calls[c] = true
}
}
if _, disabled, err := host.DetectSupportedSyscalls(target, sandbox); err != nil {
Logf(0, "failed to detect host supported syscalls: %v", err)
} else {
for c := range calls {
if reason, ok := disabled[c]; ok {
Logf(1, "unsupported syscall: %v: %v", c.Name, reason)
delete(calls, c)
}
}
}
calls, disabled := target.TransitivelyEnabledCalls(calls)
for c, reason := range disabled {
Logf(1, "transitively unsupported: %v: %v", c.Name, reason)
}
return calls
}
func (fuzzer *Fuzzer) sendInputToManager(inp RPCInput) {
a := &NewInputArgs{
Name: fuzzer.name,
RPCInput: inp,
}
if err := fuzzer.manager.Call("Manager.NewInput", a, nil); err != nil {
panic(err)
}
}
func (fuzzer *Fuzzer) addInputFromAnotherFuzzer(inp RPCInput) {
if !fuzzer.coverageEnabled {
panic("should not be called when coverage is disabled")
}
p, err := fuzzer.target.Deserialize(inp.Prog)
if err != nil {
panic(err)
}
sig := hash.Hash(inp.Prog)
sign := inp.Signal.Deserialize()
fuzzer.addInputToCorpus(p, sign, sig)
}
func (fuzzer *Fuzzer) addInputToCorpus(p *prog.Prog, sign signal.Signal, sig hash.Sig) {
fuzzer.corpusMu.Lock()
if _, ok := fuzzer.corpusHashes[sig]; !ok {
fuzzer.corpus = append(fuzzer.corpus, p)
fuzzer.corpusHashes[sig] = struct{}{}
}
fuzzer.corpusMu.Unlock()
if !sign.Empty() {
fuzzer.signalMu.Lock()
fuzzer.corpusSignal.Merge(sign)
fuzzer.maxSignal.Merge(sign)
fuzzer.signalMu.Unlock()
}
}
func (fuzzer *Fuzzer) corpusSnapshot() []*prog.Prog {
fuzzer.corpusMu.RLock()
defer fuzzer.corpusMu.RUnlock()
return fuzzer.corpus
}
func (fuzzer *Fuzzer) addMaxSignal(sign signal.Signal) {
if sign.Len() == 0 {
return
}
fuzzer.signalMu.Lock()
defer fuzzer.signalMu.Unlock()
fuzzer.maxSignal.Merge(sign)
}
func (fuzzer *Fuzzer) grabNewSignal() signal.Signal {
fuzzer.signalMu.Lock()
defer fuzzer.signalMu.Unlock()
sign := fuzzer.newSignal
if sign.Empty() {
return nil
}
fuzzer.newSignal = nil
return sign
}
func (fuzzer *Fuzzer) corpusSignalDiff(sign signal.Signal) signal.Signal {
fuzzer.signalMu.RLock()
defer fuzzer.signalMu.RUnlock()
return fuzzer.corpusSignal.Diff(sign)
}
func (fuzzer *Fuzzer) checkNewSignal(p *prog.Prog, info []ipc.CallInfo) (calls []int) {
fuzzer.signalMu.RLock()
defer fuzzer.signalMu.RUnlock()
for i, inf := range info {
diff := fuzzer.maxSignal.DiffRaw(inf.Signal, signalPrio(p.Target, p.Calls[i], &inf))
if diff.Empty() {
continue
}
calls = append(calls, i)
fuzzer.signalMu.RUnlock()
fuzzer.signalMu.Lock()
fuzzer.maxSignal.Merge(diff)
fuzzer.newSignal.Merge(diff)
fuzzer.signalMu.Unlock()
fuzzer.signalMu.RLock()
}
return
}
func signalPrio(target *prog.Target, c *prog.Call, ci *ipc.CallInfo) (prio uint8) {
if ci.Errno == 0 {
prio |= 1 << 1
}
if !target.CallContainsAny(c) {
prio |= 1 << 0
}
return
}
func (fuzzer *Fuzzer) leakCheckCallback() {
if atomic.LoadUint32(&fuzzer.leakCheckReady) != 0 {
// Scan for leaks once in a while (it is damn slow).
kmemleakScan(true)
}
}