vm/cuttlefish, vm/gce: add custom commands for reading console

For Cuttlefish we want to read the console from the emulated device
instead of the "host" GCE instance. This allows us to pass a custom
command through to gce.Pool (and then to gce.instance) which is used
instead.

We also need to update runOnHost() to use osutil directly instead of
delegating to gceInst.Run(), since it's called during VM creation. When
setting up the VM the kernel logs don't exist yet.

2 files changed, 67 insertions, 52 deletions

diff --git a/vm/cuttlefish/cuttlefish.go b/vm/cuttlefish/cuttlefish.go
index ccea7c7e7..f6f61ee16 100644
--- a/vm/cuttlefish/cuttlefish.go
+++ b/vm/cuttlefish/cuttlefish.go
@@ -15,13 +15,15 @@ import (
 	"path/filepath"
 	"time"
 
-	"github.com/google/syzkaller/pkg/log"
+	"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"
+	deviceRoot     = "/data/fuzz"
+	consoleReadCmd = "tail -f cuttlefish/instances/cvd-1/kernel.log"
 )
 
 func init() {
@@ -30,16 +32,19 @@ func init() {
 
 type Pool struct {
 	env     *vmimpl.Env
-	gcePool vmimpl.Pool
+	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 := vmimpl.Types["gce"].Ctor(env)
+	gcePool, err := gce.Ctor(env, consoleReadCmd)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create underlying GCE pool: %s", err)
 	}
@@ -63,6 +68,9 @@ func (pool *Pool) Create(workdir string, index int) (vmimpl.Instance, error) {
 	}
 
 	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,
 	}
@@ -94,24 +102,18 @@ func (pool *Pool) Create(workdir string, index int) (vmimpl.Instance, error) {
 	return inst, nil
 }
 
-func (inst *instance) runOnHost(timeout time.Duration, cmd string) error {
-	outc, errc, err := inst.gceInst.Run(timeout, nil, cmd)
-	if err != nil {
-		return fmt.Errorf("failed to run command: %s", err)
+func (inst *instance) sshArgs(command string) []string {
+	sshArgs := append(vmimpl.SSHArgs(inst.debug, inst.sshKey, 22), inst.sshUser+"@"+inst.name)
+	if inst.sshUser != "root" {
+		return append(sshArgs, "sudo", "bash", "-c", "'"+command+"'")
 	}
+	return append(sshArgs, command)
+}
 
-	for {
-		select {
-		case <-vmimpl.Shutdown:
-			return nil
-		case err := <-errc:
-			return err
-		case out, ok := <-outc:
-			if ok && inst.debug {
-				log.Logf(1, "%s", out)
-			}
-		}
-	}
+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) {
diff --git a/vm/gce/gce.go b/vm/gce/gce.go
index ef213d12e..ba05af51b 100644
--- a/vm/gce/gce.go
+++ b/vm/gce/gce.go
@@ -49,26 +49,32 @@ type Config struct {
 }
 
 type Pool struct {
-	env *vmimpl.Env
-	cfg *Config
-	GCE *gce.Context
+	env            *vmimpl.Env
+	cfg            *Config
+	GCE            *gce.Context
+	consoleReadCmd string // optional: command to read non-standard kernel console
 }
 
 type instance struct {
-	env      *vmimpl.Env
-	cfg      *Config
-	GCE      *gce.Context
-	debug    bool
-	name     string
-	ip       string
-	gceKey   string // per-instance private ssh key associated with the instance
-	sshKey   string // ssh key
-	sshUser  string
-	closed   chan bool
-	consolew io.WriteCloser
+	env            *vmimpl.Env
+	cfg            *Config
+	GCE            *gce.Context
+	debug          bool
+	name           string
+	ip             string
+	gceKey         string // per-instance private ssh key associated with the instance
+	sshKey         string // ssh key
+	sshUser        string
+	closed         chan bool
+	consolew       io.WriteCloser
+	consoleReadCmd string // optional: command to read non-standard kernel console
 }
 
 func ctor(env *vmimpl.Env) (vmimpl.Pool, error) {
+	return Ctor(env, "")
+}
+
+func Ctor(env *vmimpl.Env, consoleReadCmd string) (*Pool, error) {
 	if env.Name == "" {
 		return nil, fmt.Errorf("config param name is empty (required for GCE)")
 	}
@@ -123,9 +129,10 @@ func ctor(env *vmimpl.Env) (vmimpl.Pool, error) {
 		}
 	}
 	pool := &Pool{
-		cfg: cfg,
-		env: env,
-		GCE: GCE,
+		cfg:            cfg,
+		env:            env,
+		GCE:            GCE,
+		consoleReadCmd: consoleReadCmd,
 	}
 	return pool, nil
 }
@@ -182,16 +189,17 @@ func (pool *Pool) Create(workdir string, index int) (vmimpl.Instance, error) {
 	}
 	ok = true
 	inst := &instance{
-		env:     pool.env,
-		cfg:     pool.cfg,
-		debug:   pool.env.Debug,
-		GCE:     pool.GCE,
-		name:    name,
-		ip:      ip,
-		gceKey:  gceKey,
-		sshKey:  sshKey,
-		sshUser: sshUser,
-		closed:  make(chan bool),
+		env:            pool.env,
+		cfg:            pool.cfg,
+		debug:          pool.env.Debug,
+		GCE:            pool.GCE,
+		name:           name,
+		ip:             ip,
+		gceKey:         gceKey,
+		sshKey:         sshKey,
+		sshUser:        sshUser,
+		closed:         make(chan bool),
+		consoleReadCmd: pool.consoleReadCmd,
 	}
 	return inst, nil
 }
@@ -224,11 +232,16 @@ func (inst *instance) Run(timeout time.Duration, stop <-chan bool, command strin
 		return nil, nil, err
 	}
 
-	conAddr := fmt.Sprintf("%v.%v.%v.syzkaller.port=1@ssh-serialport.googleapis.com",
-		inst.GCE.ProjectID, inst.GCE.ZoneID, inst.name)
-	conArgs := append(vmimpl.SSHArgs(inst.debug, inst.gceKey, 9600), conAddr)
-	// TODO: remove this later (see also a comment in getSerialPortOutput).
-	conArgs = append(conArgs, "-o", "HostKeyAlgorithms=+ssh-rsa")
+	var conArgs []string
+	if inst.consoleReadCmd == "" {
+		conAddr := fmt.Sprintf("%v.%v.%v.syzkaller.port=1@ssh-serialport.googleapis.com",
+			inst.GCE.ProjectID, inst.GCE.ZoneID, inst.name)
+		conArgs = append(vmimpl.SSHArgs(inst.debug, inst.gceKey, 9600), conAddr)
+		// TODO: remove this later (see also a comment in getSerialPortOutput).
+		conArgs = append(conArgs, "-o", "HostKeyAlgorithms=+ssh-rsa")
+	} else {
+		conArgs = inst.sshArgs(inst.consoleReadCmd)
+	}
 	con := osutil.Command("ssh", conArgs...)
 	con.Env = []string{}
 	con.Stdout = conWpipe