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// Copyright 2022 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 cuttlefish allows to use Cuttlefish Android emulators hosted on Google Compute Engine
// (GCE) virtual machines as VMs. It is assumed that syz-manager also runs on GCE as VMs are
// created in the current project/zone.
//
// See https://cloud.google.com/compute/docs for details.
// In particular, how to build GCE-compatible images:
// https://cloud.google.com/compute/docs/tutorials/building-images
package cuttlefish
import (
"fmt"
"os/exec"
"path/filepath"
"time"
"github.com/google/syzkaller/pkg/osutil"
"github.com/google/syzkaller/pkg/report"
"github.com/google/syzkaller/vm/gce"
"github.com/google/syzkaller/vm/vmimpl"
)
const (
deviceRoot = "/data/fuzz"
consoleReadCmd = "tail -f cuttlefish/instances/cvd-1/kernel.log"
)
func init() {
vmimpl.Register("cuttlefish", vmimpl.Type{
Ctor: ctor,
Overcommit: true,
})
}
type Pool struct {
env *vmimpl.Env
gcePool *gce.Pool
}
type instance struct {
name string
sshKey string
sshUser string
debug bool
gceInst vmimpl.Instance
}
func ctor(env *vmimpl.Env) (vmimpl.Pool, error) {
gcePool, err := gce.Ctor(env, consoleReadCmd)
if err != nil {
return nil, fmt.Errorf("failed to create underlying GCE pool: %w", err)
}
pool := &Pool{
env: env,
gcePool: gcePool,
}
return pool, nil
}
func (pool *Pool) Count() int {
return pool.gcePool.Count()
}
func (pool *Pool) Create(workdir string, index int) (vmimpl.Instance, error) {
gceInst, err := pool.gcePool.Create(workdir, index)
if err != nil {
return nil, fmt.Errorf("failed to create underlying gce instance: %w", err)
}
inst := &instance{
name: fmt.Sprintf("%v-%v", pool.env.Name, index),
sshKey: pool.env.SSHKey,
sshUser: pool.env.SSHUser,
debug: pool.env.Debug,
gceInst: gceInst,
}
// Start a Cuttlefish device on the GCE instance.
if err := inst.runOnHost(10*time.Minute,
fmt.Sprintf("./bin/launch_cvd -daemon -kernel_path=./bzImage -initramfs_path=./initramfs.img"+
" --noenable_sandbox -report_anonymous_usage_stats=n --memory_mb=8192")); err != nil {
return nil, fmt.Errorf("failed to start cuttlefish: %w", err)
}
if err := inst.runOnHost(10*time.Minute, "adb wait-for-device"); err != nil {
return nil, fmt.Errorf("failed while waiting for device: %w", err)
}
if err := inst.runOnHost(5*time.Minute, "adb root"); err != nil {
return nil, fmt.Errorf("failed to get root access to device: %w", err)
}
if err := inst.runOnHost(5*time.Minute, fmt.Sprintf("adb shell '"+
"setprop persist.dbg.keep_debugfs_mounted 1;"+
"mount -t debugfs debugfs /sys/kernel/debug;"+
"chmod 0755 /sys/kernel/debug;"+
"mkdir %s;"+
"'", deviceRoot)); err != nil {
return nil, fmt.Errorf("failed to mount debugfs to /sys/kernel/debug: %w", err)
}
return inst, nil
}
func (inst *instance) sshArgs(command string) []string {
sshArgs := append(vmimpl.SSHArgs(inst.debug, inst.sshKey, 22, false), inst.sshUser+"@"+inst.name)
if inst.sshUser != "root" {
return append(sshArgs, "sudo", "bash", "-c", "'"+command+"'")
}
return append(sshArgs, command)
}
func (inst *instance) runOnHost(timeout time.Duration, command string) error {
_, err := osutil.RunCmd(timeout, "/root", "ssh", inst.sshArgs(command)...)
return err
}
func (inst *instance) Copy(hostSrc string) (string, error) {
gceDst, err := inst.gceInst.Copy(hostSrc)
if err != nil {
return "", fmt.Errorf("error copying to worker instance: %w", err)
}
deviceDst := filepath.Join(deviceRoot, filepath.Base(hostSrc))
pushCmd := fmt.Sprintf("adb push %s %s", gceDst, deviceDst)
if err := inst.runOnHost(5*time.Minute, pushCmd); err != nil {
return "", fmt.Errorf("error pushing to device: %w", err)
}
return deviceDst, nil
}
func (inst *instance) Forward(port int) (string, error) {
hostForward, err := inst.gceInst.Forward(port)
if err != nil {
return "", fmt.Errorf("failed to get IP/port from GCE instance: %w", err)
}
// Run socat in the background. This hangs when run from runOnHost().
cmdStr := fmt.Sprintf("nohup socat TCP-LISTEN:%d,fork TCP:%s", port, hostForward)
cmdArgs := append([]string{"-f"}, inst.sshArgs(cmdStr)...)
cmd := exec.Command("ssh", cmdArgs...)
cmd.Dir = "/root"
if err := cmd.Run(); err != nil {
return "", fmt.Errorf("unable to forward port on host: %w", err)
}
for i := 0; i < 100; i++ {
devicePort := vmimpl.RandomPort()
cmd := fmt.Sprintf("adb reverse tcp:%d tcp:%d", devicePort, port)
err = inst.runOnHost(10*time.Second, cmd)
if err == nil {
return fmt.Sprintf("127.0.0.1:%d", devicePort), nil
}
}
return "", fmt.Errorf("unable to forward port on device: %w", err)
}
func (inst *instance) Close() error {
return inst.gceInst.Close()
}
func (inst *instance) Run(timeout time.Duration, stop <-chan bool, command string) (
<-chan []byte, <-chan error, error) {
return inst.gceInst.Run(timeout, stop, fmt.Sprintf("adb shell 'cd %s; %s'", deviceRoot, command))
}
func (inst *instance) Diagnose(rep *report.Report) ([]byte, bool) {
return nil, false
}
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