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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 vm
import (
"bytes"
"errors"
"fmt"
"io"
"os"
"regexp"
"syscall"
"time"
"github.com/google/syzkaller/report"
)
// Instance represents a Linux VM or a remote physical machine.
type Instance interface {
// Copy copies a hostSrc file into vm and returns file name in vm.
Copy(hostSrc string) (string, error)
// Forward setups forwarding from within VM to host port port
// and returns address to use in VM.
Forward(port int) (string, error)
// Run runs cmd inside of the VM (think of ssh cmd).
// outc receives combined cmd and kernel console output.
// errc receives either command Wait return error or vm.TimeoutErr.
// Command is terminated after timeout. Send on the stop chan can be used to terminate it earlier.
Run(timeout time.Duration, stop <-chan bool, command string) (outc <-chan []byte, errc <-chan error, err error)
// Close stops and destroys the VM.
Close()
}
type Config struct {
Name string
Index int
Workdir string
Bin string
BinArgs string
Initrd string
Kernel string
Cmdline string
Image string
Sshkey string
Executor string
Device string
MachineType string
Cpu int
Mem int
Debug bool
}
type ctorFunc func(cfg *Config) (Instance, error)
var ctors = make(map[string]ctorFunc)
func Register(typ string, ctor ctorFunc) {
ctors[typ] = ctor
}
// Close to interrupt all pending operations.
var Shutdown = make(chan struct{})
// Create creates and boots a new VM instance.
func Create(typ string, cfg *Config) (Instance, error) {
ctor := ctors[typ]
if ctor == nil {
return nil, fmt.Errorf("unknown instance type '%v'", typ)
}
return ctor(cfg)
}
func LongPipe() (io.ReadCloser, io.WriteCloser, error) {
r, w, err := os.Pipe()
if err != nil {
return nil, nil, fmt.Errorf("failed to create pipe: %v", err)
}
for sz := 128 << 10; sz <= 2<<20; sz *= 2 {
syscall.Syscall(syscall.SYS_FCNTL, w.Fd(), syscall.F_SETPIPE_SZ, uintptr(sz))
}
return r, w, err
}
var TimeoutErr = errors.New("timeout")
func MonitorExecution(outc <-chan []byte, errc <-chan error, local, needOutput bool, ignores []*regexp.Regexp) (desc string, text, output []byte, crashed, timedout bool) {
waitForOutput := func() {
dur := time.Second
if needOutput {
dur = 10 * time.Second
}
timer := time.NewTimer(dur).C
for {
select {
case out, ok := <-outc:
if !ok {
return
}
output = append(output, out...)
case <-timer:
return
}
}
}
matchPos := 0
const (
beforeContext = 256 << 10
afterContext = 128 << 10
)
extractError := func(defaultError string) (string, []byte, []byte, bool, bool) {
// Give it some time to finish writing the error message.
waitForOutput()
if bytes.Contains(output, []byte("SYZ-FUZZER: PREEMPTED")) {
return "preempted", nil, nil, false, true
}
if !report.ContainsCrash(output[matchPos:], ignores) {
return defaultError, nil, output, defaultError != "", false
}
desc, text, start, end := report.Parse(output[matchPos:], ignores)
start = start + matchPos - beforeContext
if start < 0 {
start = 0
}
end = end + matchPos + afterContext
if end > len(output) {
end = len(output)
}
return desc, text, output[start:end], true, false
}
lastExecuteTime := time.Now()
ticker := time.NewTimer(3 * time.Minute)
tickerFired := false
for {
if !tickerFired && !ticker.Stop() {
<-ticker.C
}
tickerFired = false
ticker.Reset(3 * time.Minute)
select {
case err := <-errc:
switch err {
case nil:
// The program has exited without errors,
// but wait for kernel output in case there is some delayed oops.
return extractError("")
case TimeoutErr:
return err.Error(), nil, nil, false, true
default:
// Note: connection lost can race with a kernel oops message.
// In such case we want to return the kernel oops.
return extractError("lost connection to test machine")
}
case out := <-outc:
output = append(output, out...)
if bytes.Index(output[matchPos:], []byte("executing program")) != -1 { // syz-fuzzer output
lastExecuteTime = time.Now()
}
if bytes.Index(output[matchPos:], []byte("executed programs:")) != -1 { // syz-execprog output
lastExecuteTime = time.Now()
}
if report.ContainsCrash(output[matchPos:], ignores) {
return extractError("unknown error")
}
if len(output) > 2*beforeContext {
copy(output, output[len(output)-beforeContext:])
output = output[:beforeContext]
}
matchPos = len(output) - 128
if matchPos < 0 {
matchPos = 0
}
// In some cases kernel constantly prints something to console,
// but fuzzer is not actually executing programs.
if !local && time.Since(lastExecuteTime) > 3*time.Minute {
return "test machine is not executing programs", nil, output, true, false
}
case <-ticker.C:
tickerFired = true
if !local {
return "no output from test machine", nil, output, true, false
}
case <-Shutdown:
return "", nil, nil, false, false
}
}
}
// Sleep for d.
// If shutdown is in progress, return false prematurely.
func SleepInterruptible(d time.Duration) bool {
select {
case <-time.After(d):
return true
case <-Shutdown:
return false
}
}
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