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verifier.go
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verifier.go
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// Copyright 2021 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 (
"errors"
"fmt"
"io"
"math/rand"
"os"
"os/signal"
"path/filepath"
"strings"
"sync"
"time"
"github.com/google/syzkaller/pkg/instance"
"github.com/google/syzkaller/pkg/log"
"github.com/google/syzkaller/pkg/osutil"
"github.com/google/syzkaller/pkg/rpctype"
"github.com/google/syzkaller/prog"
"github.com/google/syzkaller/vm"
)
// Verifier TODO.
type Verifier struct {
pools map[int]*poolInfo
vmStop chan bool
// Location of a working directory for all VMs for the syz-verifier process.
// Outputs here include:
// - <workdir>/crashes/<OS-Arch>/*: crash output files grouped by OS/Arch
// - <workdir>/corpus.db: corpus with interesting programs
// - <workdir>/<OS-Arch>/instance-x: per VM instance temporary files
// grouped by OS/Arch
workdir string
crashdir string
resultsdir string
target *prog.Target
runnerBin string
executorBin string
progGeneratorInit sync.WaitGroup
choiceTable *prog.ChoiceTable
progIdx int
addr string
srv *RPCServer
calls map[*prog.Syscall]bool
reasons map[*prog.Syscall]string
reportReasons bool
stats *Stats
statsWrite io.Writer
newEnv bool
reruns int
// We use single queue for every kernel environment.
tasksMutex sync.Mutex
onTaskAdded *sync.Cond
kernelEnvTasks [][]*ExecTaskQueue
taskFactory *ExecTaskFactory
}
func (vrf *Verifier) Init() {
vrf.progGeneratorInit.Add(1)
vrf.onTaskAdded = sync.NewCond(&vrf.tasksMutex)
vrf.kernelEnvTasks = make([][]*ExecTaskQueue, len(vrf.pools))
for i := range vrf.kernelEnvTasks {
vrf.kernelEnvTasks[i] = make([]*ExecTaskQueue, EnvironmentsCount)
for j := range vrf.kernelEnvTasks[i] {
vrf.kernelEnvTasks[i][j] = MakeExecTaskQueue()
}
}
srv, err := startRPCServer(vrf)
if err != nil {
log.Fatalf("failed to initialise RPC server: %v", err)
}
vrf.srv = srv
vrf.taskFactory = MakeExecTaskFactory()
}
func (vrf *Verifier) StartProgramsAnalysis() {
go func() {
vrf.progGeneratorInit.Wait()
type AnalysisResult struct {
Diff []*ExecResult
Prog *prog.Prog
}
results := make(chan *AnalysisResult)
go func() {
for result := range results {
if result.Diff != nil {
vrf.SaveDiffResults(result.Diff, result.Prog)
}
}
}()
for i := 0; i < 100; i++ {
go func() {
for {
prog := vrf.generate()
results <- &AnalysisResult{
vrf.TestProgram(prog),
prog,
}
}
}()
}
}()
}
func (vrf *Verifier) GetRunnerTask(kernel int, existing EnvDescr) *rpctype.ExecTask {
vrf.tasksMutex.Lock()
defer vrf.tasksMutex.Unlock()
for {
for env := existing; env >= AnyEnvironment; env-- {
if task, ok := vrf.kernelEnvTasks[kernel][env].PopTask(); ok {
return task.ToRPC()
}
}
vrf.onTaskAdded.Wait()
}
}
func (vrf *Verifier) PutExecResult(result *ExecResult) {
c := vrf.taskFactory.GetExecResultChan(result.ExecTaskID)
c <- result
}
// TestProgram return the results slice if some exec diff was found.
func (vrf *Verifier) TestProgram(prog *prog.Prog) (result []*ExecResult) {
steps := []EnvDescr{
NewEnvironment,
NewEnvironment,
}
defer vrf.stats.TotalProgs.Inc()
for i, env := range steps {
stepRes, err := vrf.Run(prog, env)
if err != nil {
vrf.stats.ExecErrorProgs.Inc()
return
}
vrf.AddCallsExecutionStat(stepRes, prog)
if stepRes[0].IsEqual(stepRes[1]) {
if i != 0 {
vrf.stats.FlakyProgs.Inc()
}
return
}
if i == len(steps)-1 {
vrf.stats.MismatchingProgs.Inc()
return stepRes
}
}
return
}
// Run sends the program for verification to execution queues and return
// result once it's ready.
// In case of time-out, return (nil, error).
func (vrf *Verifier) Run(prog *prog.Prog, env EnvDescr) (result []*ExecResult, err error) {
totalKernels := len(vrf.kernelEnvTasks)
result = make([]*ExecResult, totalKernels)
wg := sync.WaitGroup{}
wg.Add(totalKernels)
for i := 0; i < totalKernels; i++ {
i := i
q := vrf.kernelEnvTasks[i][env]
go func() {
defer wg.Done()
task := vrf.taskFactory.MakeExecTask(prog)
defer vrf.taskFactory.DeleteExecTask(task)
vrf.tasksMutex.Lock()
q.PushTask(task)
vrf.onTaskAdded.Signal()
vrf.tasksMutex.Unlock()
result[i] = <-task.ExecResultChan
}()
}
wg.Wait()
for _, item := range result {
if item == nil {
err = errors.New("something went wrong and we exit w/o results")
return nil, err
}
if item.Error != nil {
err = item.Error
return nil, err
}
}
return result, nil
}
// SetPrintStatAtSIGINT asks Stats object to report verification
// statistics when an os.Interrupt occurs and Exit().
func (vrf *Verifier) SetPrintStatAtSIGINT() error {
if vrf.stats == nil {
return errors.New("verifier.stats is nil")
}
osSignalChannel := make(chan os.Signal, 1)
signal.Notify(osSignalChannel, os.Interrupt)
go func() {
<-osSignalChannel
defer os.Exit(0)
totalExecutionTime := time.Since(vrf.stats.StartTime.Get()).Minutes()
if !vrf.stats.MismatchesFound() {
fmt.Fprint(vrf.statsWrite, "No mismatches occurred until syz-verifier was stopped.")
} else {
fmt.Fprintf(vrf.statsWrite, "%s", vrf.stats.GetTextDescription(totalExecutionTime))
}
}()
return nil
}
func (vrf *Verifier) startInstances() {
for poolID, pi := range vrf.pools {
totalInstances := pi.pool.Count()
for vmID := 0; vmID < totalInstances; vmID++ {
go func(pi *poolInfo, poolID, vmID int) {
for {
vrf.createAndManageInstance(pi, poolID, vmID)
}
}(pi, poolID, vmID)
}
}
}
func (vrf *Verifier) createAndManageInstance(pi *poolInfo, poolID, vmID int) {
inst, err := pi.pool.Create(vmID)
if err != nil {
log.Fatalf("failed to create instance: %v", err)
}
defer inst.Close()
defer vrf.srv.cleanup(poolID, vmID)
fwdAddr, err := inst.Forward(vrf.srv.port)
if err != nil {
log.Fatalf("failed to set up port forwarding: %v", err)
}
runnerBin, err := inst.Copy(vrf.runnerBin)
if err != nil {
log.Fatalf(" failed to copy runner binary: %v", err)
}
_, err = inst.Copy(vrf.executorBin)
if err != nil {
log.Fatalf("failed to copy executor binary: %v", err)
}
cmd := instance.RunnerCmd(runnerBin, fwdAddr, vrf.target.OS, vrf.target.Arch, poolID, 0, false, vrf.newEnv)
_, _, err = inst.Run(pi.cfg.Timeouts.VMRunningTime, pi.Reporter, cmd, vm.ExitTimeout, vm.StopChan(vrf.vmStop))
if err != nil {
log.Fatalf("failed to start runner: %v", err)
}
log.Logf(0, "reboot the VM in pool %d", poolID)
}
// finalizeCallSet removes the system calls that are not supported from the set
// of enabled system calls and reports the reason to the io.Writer (either
// because the call is not supported by one of the kernels or because the call
// is missing some transitive dependencies). The resulting set of system calls
// will be used to build the prog.ChoiceTable.
func (vrf *Verifier) finalizeCallSet(w io.Writer) {
for c := range vrf.reasons {
delete(vrf.calls, c)
}
// Find and report to the user all the system calls that need to be
// disabled due to missing dependencies.
_, disabled := vrf.target.TransitivelyEnabledCalls(vrf.calls)
for c, reason := range disabled {
vrf.reasons[c] = reason
delete(vrf.calls, c)
}
if len(vrf.calls) == 0 {
log.Logf(0, "All enabled system calls are missing dependencies or not"+
" supported by some kernels, exiting syz-verifier.")
}
if !vrf.reportReasons {
return
}
fmt.Fprintln(w, "The following calls have been disabled:")
for c, reason := range vrf.reasons {
fmt.Fprintf(w, "\t%v: %v\n", c.Name, reason)
}
}
// AddCallsExecutionStat ignore all the calls after the first mismatch.
func (vrf *Verifier) AddCallsExecutionStat(results []*ExecResult, program *prog.Prog) {
rr := CompareResults(results, program)
for _, cr := range rr.Reports {
vrf.stats.Calls.IncCallOccurrenceCount(cr.Call)
}
for _, cr := range rr.Reports {
if !cr.Mismatch {
continue
}
vrf.stats.IncCallMismatches(cr.Call)
for _, state := range cr.States {
if state0 := cr.States[0]; state0 != state {
vrf.stats.Calls.AddState(cr.Call, state)
vrf.stats.Calls.AddState(cr.Call, state0)
}
}
break
}
}
// SaveDiffResults extract diff and save result on the persistent storage.
func (vrf *Verifier) SaveDiffResults(results []*ExecResult, program *prog.Prog) bool {
rr := CompareResults(results, program)
oldest := 0
var oldestTime time.Time
for i := 0; i < maxResultReports; i++ {
info, err := os.Stat(filepath.Join(vrf.resultsdir, fmt.Sprintf("result-%d", i)))
if err != nil {
// There are only i-1 report files so the i-th one
// can be created.
oldest = i
break
}
// Otherwise, search for the oldest report file to
// overwrite as newer result reports are more useful.
if oldestTime.IsZero() || info.ModTime().Before(oldestTime) {
oldest = i
oldestTime = info.ModTime()
}
}
err := osutil.WriteFile(filepath.Join(vrf.resultsdir,
fmt.Sprintf("result-%d", oldest)), createReport(rr, len(vrf.pools)))
if err != nil {
log.Logf(0, "failed to write result-%d file, err %v", oldest, err)
}
log.Logf(0, "result-%d written successfully", oldest)
return true
}
// generate returns a newly generated program or error.
func (vrf *Verifier) generate() *prog.Prog {
vrf.progGeneratorInit.Wait()
rnd := rand.New(rand.NewSource(time.Now().UnixNano() + 1e12))
return vrf.target.Generate(rnd, prog.RecommendedCalls, vrf.choiceTable)
}
func createReport(rr *ResultReport, pools int) []byte {
calls := strings.Split(rr.Prog, "\n")
calls = calls[:len(calls)-1]
data := "ERRNO mismatches found for program:\n\n"
for idx, cr := range rr.Reports {
tick := "[=]"
if cr.Mismatch {
tick = "[!]"
}
data += fmt.Sprintf("%s %s\n", tick, calls[idx])
// Ensure results are ordered by pool index.
for i := 0; i < pools; i++ {
state := cr.States[i]
data += fmt.Sprintf("\t↳ Pool: %d, %s\n", i, state)
}
data += "\n"
}
return []byte(data)
}