rkt: Fix incomplete selinux context string when the option is partial.

Add Getfilecon() into the selinux interface.

pkg/kubelet/kubelet.go

@@ -1209,7 +1209,7 @@ func (kl *Kubelet) relabelVolumes(pod *api.Pod, volumes kubecontainer.VolumeMap)
 		return err
 	}
 
-	chconRunner := selinux.NewChconRunner()
+	selinuxRunner := selinux.NewSelinuxContextRunner()
 	// Apply the pod's Level to the rootDirContext
 	rootDirSELinuxOptions, err := securitycontext.ParseSELinuxOptions(rootDirContext)
 	if err != nil {
@@ -1226,7 +1226,7 @@ func (kl *Kubelet) relabelVolumes(pod *api.Pod, volumes kubecontainer.VolumeMap)
 				if err != nil {
 					return err
 				}
-				return chconRunner.SetContext(path, volumeContext)
+				return selinuxRunner.SetContext(path, volumeContext)
 			})
 			if err != nil {
 				return err

pkg/kubelet/rkt/rkt.go

@@ -58,6 +58,7 @@ import (
 	"k8s.io/kubernetes/pkg/util/errors"
 	utilexec "k8s.io/kubernetes/pkg/util/exec"
 	"k8s.io/kubernetes/pkg/util/flowcontrol"
+	"k8s.io/kubernetes/pkg/util/selinux"
 	utilstrings "k8s.io/kubernetes/pkg/util/strings"
 	utilwait "k8s.io/kubernetes/pkg/util/wait"
 )
@@ -1002,6 +1003,34 @@ func (r *Runtime) preparePodArgs(manifest *appcschema.PodManifest, manifestFileN
 	return cmds
 }
 
+func (r *Runtime) getSelinuxContext(opt *api.SELinuxOptions) (string, error) {
+	selinuxRunner := selinux.NewSelinuxContextRunner()
+	str, err := selinuxRunner.Getfilecon(r.config.Dir)
+	if err != nil {
+		return "", err
+	}
+
+	ctx := strings.SplitN(str, ":", 4)
+	if len(ctx) != 4 {
+		return "", fmt.Errorf("malformated selinux context")
+	}
+
+	if opt.User != "" {
+		ctx[0] = opt.User
+	}
+	if opt.Role != "" {
+		ctx[1] = opt.Role
+	}
+	if opt.Type != "" {
+		ctx[2] = opt.Type
+	}
+	if opt.Level != "" {
+		ctx[3] = opt.Level
+	}
+
+	return strings.Join(ctx, ":"), nil
+}
+
 // preparePod will:
 //
 // 1. Invoke 'rkt prepare' to prepare the pod, and get the rkt pod uuid.
@@ -1073,7 +1102,11 @@ func (r *Runtime) preparePod(pod *api.Pod, podIP string, pullSecrets []api.Secre
 
 	if pod.Spec.SecurityContext != nil && pod.Spec.SecurityContext.SELinuxOptions != nil {
 		opt := pod.Spec.SecurityContext.SELinuxOptions
-		selinuxContext := fmt.Sprintf("%s:%s:%s:%s", opt.User, opt.Role, opt.Type, opt.Level)
+		selinuxContext, err := r.getSelinuxContext(opt)
+		if err != nil {
+			glog.Errorf("rkt: Failed to construct selinux context with selinux option %q: %v", opt, err)
+			return "", nil, err
+		}
 		units = append(units, newUnitOption("Service", "SELinuxContext", selinuxContext))
 	}
 

pkg/kubelet/rkt/rkt_test.go

@@ -1172,27 +1172,6 @@ func TestGenerateRunCommand(t *testing.T) {
 			nil,
 			fmt.Sprintf("/bin/rkt/rkt --insecure-options=image,ondisk --local-config=/var/rkt/local/data --dir=/var/data run-prepared --net=host --hostname=%s rkt-uuid-foo", hostName),
 		},
-		// Case #5, returns --net=host --no-overlay
-		{
-			&api.Pod{
-				ObjectMeta: api.ObjectMeta{
-					Name: "pod-name-foo",
-				},
-				Spec: api.PodSpec{
-					SecurityContext: &api.PodSecurityContext{
-						HostNetwork:    true,
-						SELinuxOptions: &api.SELinuxOptions{},
-					},
-				},
-			},
-			"rkt-uuid-foo",
-			"",
-			[]string{""},
-			[]string{""},
-			"pod-hostname-foo",
-			nil,
-			fmt.Sprintf("/bin/rkt/rkt --insecure-options=image,ondisk --local-config=/var/rkt/local/data --dir=/var/data run-prepared --no-overlay=true --net=host --hostname=%s rkt-uuid-foo", hostName),
-		},
 	}
 
 	rkt := &Runtime{

pkg/util/selinux/selinux.go

@@ -16,12 +16,14 @@ limitations under the License.
 
 package selinux
 
-// chconRunner knows how to chcon a directory.
-type ChconRunner interface {
+// SelinuxContextRunner knows how to chcon of a directory and
+// how to get the selinux context of a file.
+type SelinuxContextRunner interface {
 	SetContext(dir, context string) error
+	Getfilecon(path string) (string, error)
 }
 
-// newChconRunner returns a new chconRunner.
-func NewChconRunner() ChconRunner {
-	return &realChconRunner{}
+// NewSelinuxContextRunner returns a new chconRunner.
+func NewSelinuxContextRunner() SelinuxContextRunner {
+	return &realSelinuxContextRunner{}
 }

pkg/util/selinux/selinux_linux.go

@@ -19,12 +19,14 @@ limitations under the License.
 package selinux
 
 import (
+	"fmt"
+
 	"github.com/opencontainers/runc/libcontainer/selinux"
 )
 
-type realChconRunner struct{}
+type realSelinuxContextRunner struct{}
 
-func (_ *realChconRunner) SetContext(dir, context string) error {
+func (_ *realSelinuxContextRunner) SetContext(dir, context string) error {
 	// If SELinux is not enabled, return an empty string
 	if !selinux.SelinuxEnabled() {
 		return nil
@@ -32,3 +34,10 @@ func (_ *realChconRunner) SetContext(dir, context string) error {
 
 	return selinux.Setfilecon(dir, context)
 }
+
+func (_ *realSelinuxContextRunner) Getfilecon(path string) (string, error) {
+	if !selinux.SelinuxEnabled() {
+		return "", fmt.Errorf("SELinux is not enabled")
+	}
+	return selinux.Getfilecon(path)
+}

pkg/util/selinux/selinux_unsupported.go

@@ -18,9 +18,14 @@ limitations under the License.
 
 package selinux
 
-type realChconRunner struct{}
+type realSelinuxContextRunner struct{}
 
-func (_ *realChconRunner) SetContext(dir, context string) error {
+func (_ *realSelinuxContextRunner) SetContext(dir, context string) error {
 	// NOP
 	return nil
 }
+
+func (_ *realSelinuxContextRunner) Getfilecon(path string) (string, error) {
+	// NOP
+	return "", nil
+}