/
kvm.go
301 lines (272 loc) · 6.77 KB
/
kvm.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 kvm provides VMs based on lkvm (kvmtool) virtualization.
// It is not well tested.
package kvm
import (
"fmt"
"os"
"os/exec"
"path/filepath"
"runtime"
"strconv"
"sync"
"time"
"github.com/google/syzkaller/pkg/config"
"github.com/google/syzkaller/pkg/osutil"
"github.com/google/syzkaller/vm/vmimpl"
)
const (
hostAddr = "192.168.33.1"
)
func init() {
vmimpl.Register("kvm", ctor)
}
type Config struct {
Count int // number of VMs to use
Lkvm string // lkvm binary name
Kernel string // e.g. arch/x86/boot/bzImage
Cmdline string // kernel command line
CPU int // number of VM CPUs
Mem int // amount of VM memory in MBs
}
type Pool struct {
env *vmimpl.Env
cfg *Config
}
type instance struct {
cfg *Config
sandbox string
sandboxPath string
lkvm *exec.Cmd
readerC chan error
waiterC chan error
debug bool
mu sync.Mutex
outputB []byte
outputC chan []byte
}
func ctor(env *vmimpl.Env) (vmimpl.Pool, error) {
cfg := &Config{
Count: 1,
Lkvm: "lkvm",
}
if err := config.LoadData(env.Config, cfg); err != nil {
return nil, fmt.Errorf("failed to parse kvm vm config: %v", err)
}
if cfg.Count < 1 || cfg.Count > 1000 {
return nil, fmt.Errorf("invalid config param count: %v, want [1, 1000]", cfg.Count)
}
if env.Debug {
cfg.Count = 1
}
if env.Image != "" {
return nil, fmt.Errorf("lkvm does not support custom images")
}
if _, err := exec.LookPath(cfg.Lkvm); err != nil {
return nil, err
}
if !osutil.IsExist(cfg.Kernel) {
return nil, fmt.Errorf("kernel file '%v' does not exist", cfg.Kernel)
}
if cfg.CPU < 1 || cfg.CPU > 1024 {
return nil, fmt.Errorf("invalid config param cpu: %v, want [1-1024]", cfg.CPU)
}
if cfg.Mem < 128 || cfg.Mem > 1048576 {
return nil, fmt.Errorf("invalid config param mem: %v, want [128-1048576]", cfg.Mem)
}
cfg.Kernel = osutil.Abs(cfg.Kernel)
pool := &Pool{
cfg: cfg,
env: env,
}
return pool, nil
}
func (pool *Pool) Count() int {
return pool.cfg.Count
}
func (pool *Pool) Create(workdir string, index int) (vmimpl.Instance, error) {
sandbox := fmt.Sprintf("syz-%v", index)
inst := &instance{
cfg: pool.cfg,
sandbox: sandbox,
sandboxPath: filepath.Join(os.Getenv("HOME"), ".lkvm", sandbox),
debug: pool.env.Debug,
}
closeInst := inst
defer func() {
if closeInst != nil {
closeInst.Close()
}
}()
os.RemoveAll(inst.sandboxPath)
os.Remove(inst.sandboxPath + ".sock")
out, err := osutil.Command(inst.cfg.Lkvm, "setup", sandbox).CombinedOutput()
if err != nil {
return nil, fmt.Errorf("failed to lkvm setup: %v\n%s", err, out)
}
scriptPath := filepath.Join(workdir, "script.sh")
if err := osutil.WriteExecFile(scriptPath, []byte(script)); err != nil {
return nil, fmt.Errorf("failed to create temp file: %v", err)
}
rpipe, wpipe, err := osutil.LongPipe()
if err != nil {
return nil, fmt.Errorf("failed to create pipe: %v", err)
}
inst.lkvm = osutil.Command("taskset", "-c", strconv.Itoa(index%runtime.NumCPU()),
inst.cfg.Lkvm, "sandbox",
"--disk", inst.sandbox,
"--kernel", inst.cfg.Kernel,
"--params", "slub_debug=UZ "+inst.cfg.Cmdline,
"--mem", strconv.Itoa(inst.cfg.Mem),
"--cpus", strconv.Itoa(inst.cfg.CPU),
"--network", "mode=user",
"--sandbox", scriptPath,
)
inst.lkvm.Stdout = wpipe
inst.lkvm.Stderr = wpipe
if err := inst.lkvm.Start(); err != nil {
rpipe.Close()
wpipe.Close()
return nil, fmt.Errorf("failed to start lkvm: %v", err)
}
// Start output reading goroutine.
inst.readerC = make(chan error)
go func() {
var buf [64 << 10]byte
for {
n, err := rpipe.Read(buf[:])
if n != 0 {
if inst.debug {
os.Stdout.Write(buf[:n])
os.Stdout.Write([]byte{'\n'})
}
inst.mu.Lock()
inst.outputB = append(inst.outputB, buf[:n]...)
if inst.outputC != nil {
select {
case inst.outputC <- inst.outputB:
inst.outputB = nil
default:
}
}
inst.mu.Unlock()
time.Sleep(time.Millisecond)
}
if err != nil {
rpipe.Close()
inst.readerC <- err
return
}
}
}()
// Wait for the lkvm asynchronously.
inst.waiterC = make(chan error, 1)
go func() {
err := inst.lkvm.Wait()
wpipe.Close()
inst.waiterC <- err
}()
// Wait for the script to start serving.
_, errc, err := inst.Run(10*time.Minute, nil, "mount -t debugfs none /sys/kernel/debug/")
if err == nil {
err = <-errc
}
if err != nil {
return nil, fmt.Errorf("failed to run script: %v", err)
}
closeInst = nil
return inst, nil
}
func (inst *instance) Close() {
if inst.lkvm != nil {
inst.lkvm.Process.Kill()
err := <-inst.waiterC
inst.waiterC <- err // repost it for waiting goroutines
<-inst.readerC
}
os.RemoveAll(inst.sandboxPath)
os.Remove(inst.sandboxPath + ".sock")
}
func (inst *instance) Forward(port int) (string, error) {
return fmt.Sprintf("%v:%v", hostAddr, port), nil
}
func (inst *instance) Copy(hostSrc string) (string, error) {
vmDst := filepath.Join("/", filepath.Base(hostSrc))
dst := filepath.Join(inst.sandboxPath, vmDst)
if err := osutil.CopyFile(hostSrc, dst); err != nil {
return "", err
}
if err := os.Chmod(dst, 0777); err != nil {
return "", err
}
return vmDst, nil
}
func (inst *instance) Run(timeout time.Duration, stop <-chan bool, command string) (
<-chan []byte, <-chan error, error) {
outputC := make(chan []byte, 10)
errorC := make(chan error, 1)
inst.mu.Lock()
inst.outputB = nil
inst.outputC = outputC
inst.mu.Unlock()
cmdFile := filepath.Join(inst.sandboxPath, "/syz-cmd")
tmpFile := cmdFile + "-tmp"
if err := osutil.WriteExecFile(tmpFile, []byte(command)); err != nil {
return nil, nil, err
}
if err := os.Rename(tmpFile, cmdFile); err != nil {
return nil, nil, err
}
signal := func(err error) {
inst.mu.Lock()
if inst.outputC == outputC {
inst.outputB = nil
inst.outputC = nil
}
inst.mu.Unlock()
errorC <- err
}
go func() {
timeoutTicker := time.NewTicker(timeout)
secondTicker := time.NewTicker(time.Second)
var resultErr error
loop:
for {
select {
case <-timeoutTicker.C:
resultErr = vmimpl.ErrTimeout
break loop
case <-stop:
resultErr = vmimpl.ErrTimeout
break loop
case <-secondTicker.C:
if !osutil.IsExist(cmdFile) {
resultErr = nil
break loop
}
case err := <-inst.waiterC:
inst.waiterC <- err // repost it for Close
resultErr = fmt.Errorf("lkvm exited")
break loop
}
}
signal(resultErr)
timeoutTicker.Stop()
secondTicker.Stop()
}()
return outputC, errorC, nil
}
func (inst *instance) Diagnose() bool {
return false
}
const script = `#! /bin/bash
while true; do
if [ -e "/syz-cmd" ]; then
/syz-cmd
rm -f /syz-cmd
else
sleep 1
fi
done
`