1 files changed, 38 insertions, 10 deletions

diff --git a/libpod/networking_linux.go b/libpod/networking_linux.go
index f9caf26d1..2450bd6b1 100644
--- a/libpod/networking_linux.go
+++ b/libpod/networking_linux.go
@@ -134,15 +134,29 @@ type slirp4netnsCmd struct {
 	Args    slirp4netnsCmdArg `json:"arguments"`
 }
 
+func checkSlirpFlags(path string) (bool, bool, error) {
+	cmd := exec.Command(path, "--help")
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return false, false, err
+	}
+	return strings.Contains(string(out), "--disable-host-loopback"), strings.Contains(string(out), "--mtu"), nil
+}
+
 // Configure the network namespace for a rootless container
 func (r *Runtime) setupRootlessNetNS(ctr *Container) (err error) {
 	defer ctr.rootlessSlirpSyncR.Close()
 	defer ctr.rootlessSlirpSyncW.Close()
 
-	path, err := exec.LookPath("slirp4netns")
-	if err != nil {
-		logrus.Errorf("could not find slirp4netns, the network namespace won't be configured: %v", err)
-		return nil
+	path := r.config.NetworkCmdPath
+
+	if path == "" {
+		var err error
+		path, err = exec.LookPath("slirp4netns")
+		if err != nil {
+			logrus.Errorf("could not find slirp4netns, the network namespace won't be configured: %v", err)
+			return nil
+		}
 	}
 
 	syncR, syncW, err := os.Pipe()
@@ -154,13 +168,24 @@ func (r *Runtime) setupRootlessNetNS(ctr *Container) (err error) {
 
 	havePortMapping := len(ctr.Config().PortMappings) > 0
 	apiSocket := filepath.Join(r.ociRuntime.tmpDir, fmt.Sprintf("%s.net", ctr.config.ID))
-	var cmd *exec.Cmd
+
+	cmdArgs := []string{}
 	if havePortMapping {
-		// if we need ports to be mapped from the host, create a API socket to use for communicating with slirp4netns.
-		cmd = exec.Command(path, "-c", "-e", "3", "-r", "4", "--api-socket", apiSocket, fmt.Sprintf("%d", ctr.state.PID), "tap0")
-	} else {
-		cmd = exec.Command(path, "-c", "-e", "3", "-r", "4", fmt.Sprintf("%d", ctr.state.PID), "tap0")
+		cmdArgs = append(cmdArgs, "--api-socket", apiSocket, fmt.Sprintf("%d", ctr.state.PID))
+	}
+	dhp, mtu, err := checkSlirpFlags(path)
+	if err != nil {
+		return errors.Wrapf(err, "error checking slirp4netns binary %s", path)
+	}
+	if dhp {
+		cmdArgs = append(cmdArgs, "--disable-host-loopback")
 	}
+	if mtu {
+		cmdArgs = append(cmdArgs, "--mtu", "65520")
+	}
+	cmdArgs = append(cmdArgs, "-c", "-e", "3", "-r", "4", fmt.Sprintf("%d", ctr.state.PID), "tap0")
+
+	cmd := exec.Command(path, cmdArgs...)
 
 	cmd.SysProcAttr = &syscall.SysProcAttr{
 		Setpgid: true,
@@ -190,9 +215,12 @@ func (r *Runtime) setupRootlessNetNS(ctr *Container) (err error) {
 				if pid != cmd.Process.Pid {
 					continue
 				}
-				if status.Exited() || status.Signaled() {
+				if status.Exited() {
 					return errors.New("slirp4netns failed")
 				}
+				if status.Signaled() {
+					return errors.New("slirp4netns killed by signal")
+				}
 				continue
 			}
 			return errors.Wrapf(err, "failed to read from slirp4netns sync pipe")