syz/targets: add SyzExecutorCmd flag

This commit adds a new attribute to syzkaller targets that tells
syzkaller how to invoke the syz-executor command.

Some systems, like Fuchsia, are now building syz-executor as part of the
build, and there is no need to copy it over, or to run it from `/tmp`.
In fact, that might stop working at some time in the future in Fuchsia.

All places that used to copy syz-executor into the target machine will
now check for the SyzExecutorCmd flag, and won't copy it if the flag is
set.

2 files changed, 31 insertions, 15 deletions

diff --git a/pkg/instance/instance.go b/pkg/instance/instance.go
index 775366667..5adc9dc63 100644
--- a/pkg/instance/instance.go
+++ b/pkg/instance/instance.go
@@ -300,16 +300,23 @@ func (inst *inst) testInstance() error {
 	if err != nil {
 		return fmt.Errorf("failed to setup port forwarding: %v", err)
 	}
+
 	fuzzerBin, err := inst.vm.Copy(inst.cfg.SyzFuzzerBin)
 	if err != nil {
 		return &TestError{Title: fmt.Sprintf("failed to copy test binary to VM: %v", err)}
 	}
-	executorBin, err := inst.vm.Copy(inst.cfg.SyzExecutorBin)
-	if err != nil {
-		return &TestError{Title: fmt.Sprintf("failed to copy test binary to VM: %v", err)}
+
+	// If SyzExecutorCmd is provided, it means that syz-executor is already in
+	// the image, so no need to copy it.
+	executorCmd := targets.Get(inst.cfg.TargetOS, inst.cfg.TargetArch).SyzExecutorCmd
+	if executorCmd == "" {
+		executorCmd, err = inst.vm.Copy(inst.cfg.SyzExecutorBin)
+		if err != nil {
+			return &TestError{Title: fmt.Sprintf("failed to copy test binary to VM: %v", err)}
+		}
 	}
 
-	cmd := OldFuzzerCmd(fuzzerBin, executorBin, "test", inst.cfg.TargetOS, inst.cfg.TargetArch, fwdAddr,
+	cmd := OldFuzzerCmd(fuzzerBin, executorCmd, "test", inst.cfg.TargetOS, inst.cfg.TargetArch, fwdAddr,
 		inst.cfg.Sandbox, 0, inst.cfg.Cover, true)
 	outc, errc, err := inst.vm.Run(10*time.Minute, nil, cmd)
 	if err != nil {
@@ -340,9 +347,14 @@ func (inst *inst) testRepro() error {
 	if err != nil {
 		return &TestError{Title: fmt.Sprintf("failed to copy test binary to VM: %v", err)}
 	}
-	executorBin, err := inst.vm.Copy(cfg.SyzExecutorBin)
-	if err != nil {
-		return &TestError{Title: fmt.Sprintf("failed to copy test binary to VM: %v", err)}
+	// If SyzExecutorCmd is provided, it means that syz-executor is already in
+	// the image, so no need to copy it.
+	executorCmd := targets.Get(cfg.TargetOS, cfg.TargetArch).SyzExecutorCmd
+	if executorCmd == "" {
+		executorCmd, err = inst.vm.Copy(inst.cfg.SyzExecutorBin)
+		if err != nil {
+			return &TestError{Title: fmt.Sprintf("failed to copy test binary to VM: %v", err)}
+		}
 	}
 	progFile := filepath.Join(cfg.Workdir, "repro.prog")
 	if err := osutil.WriteFile(progFile, inst.reproSyz); err != nil {
@@ -366,7 +378,7 @@ func (inst *inst) testRepro() error {
 	if !opts.Fault {
 		opts.FaultCall = -1
 	}
-	cmdSyz := ExecprogCmd(execprogBin, executorBin, cfg.TargetOS, cfg.TargetArch, opts.Sandbox,
+	cmdSyz := ExecprogCmd(execprogBin, executorCmd, cfg.TargetOS, cfg.TargetArch, opts.Sandbox,
 		true, true, true, cfg.Procs, opts.FaultCall, opts.FaultNth, vmProgFile)
 	if err := inst.testProgram(cmdSyz, 7*time.Minute); err != nil {
 		return err
diff --git a/pkg/repro/repro.go b/pkg/repro/repro.go
index c9ba11af0..2faefe306 100644
--- a/pkg/repro/repro.go
+++ b/pkg/repro/repro.go
@@ -18,6 +18,7 @@ import (
 	"github.com/google/syzkaller/pkg/osutil"
 	"github.com/google/syzkaller/pkg/report"
 	"github.com/google/syzkaller/prog"
+	"github.com/google/syzkaller/sys/targets"
 	"github.com/google/syzkaller/vm"
 )
 
@@ -138,18 +139,21 @@ func Run(crashLog []byte, cfg *mgrconfig.Config, reporter report.Reporter, vmPoo
 						time.Sleep(10 * time.Second)
 						continue
 					}
-					executorBin, err := vmInst.Copy(cfg.SyzExecutorBin)
-					if err != nil {
-						ctx.reproLog(0, "failed to copy to VM: %v", err)
-						vmInst.Close()
-						time.Sleep(10 * time.Second)
-						continue
+					executorCmd := targets.Get(cfg.TargetOS, cfg.TargetArch).SyzExecutorCmd
+					if executorCmd == "" {
+						executorCmd, err = vmInst.Copy(cfg.SyzExecutorBin)
+						if err != nil {
+							ctx.reproLog(0, "failed to copy to VM: %v", err)
+							vmInst.Close()
+							time.Sleep(10 * time.Second)
+							continue
+						}
 					}
 					inst = &instance{
 						Instance:    vmInst,
 						index:       vmIndex,
 						execprogBin: execprogBin,
-						executorBin: executorBin,
+						executorBin: executorCmd,
 					}
 					break
 				}