Reconstruct SELinux mount option

When reconstructing volumes from disk after kubelet restart, reconstruct
also context=XYZ mount option and add it to the ActualStateOfWorld.

pkg/kubelet/volumemanager/reconciler/reconstruct.go

@@ -160,7 +160,6 @@ func (rc *reconciler) updateStates(volumesNeedUpdate map[v1.UniqueVolumeName]*gl
 				klog.ErrorS(err, "Could not find device mount path for volume", "volumeName", gvl.volumeName)
 				continue
 			}
-			// TODO(jsafrane): add reconstructed SELinux context
 			err = rc.actualStateOfWorld.MarkDeviceAsMounted(gvl.volumeName, gvl.devicePath, deviceMountPath, "")
 			if err != nil {
 				klog.ErrorS(err, "Could not mark device is mounted to actual state of world", "volume", gvl.volumeName)

pkg/kubelet/volumemanager/reconciler/reconstruct_common.go

@@ -56,6 +56,7 @@ type reconstructedVolume struct {
 	mounter             volumepkg.Mounter
 	deviceMounter       volumepkg.DeviceMounter
 	blockVolumeMapper   volumepkg.BlockVolumeMapper
+	seLinuxMountContext string
 }
 
 // globalVolumeInfo stores reconstructed volume information
@@ -211,6 +212,9 @@ func (rc *reconciler) reconstructVolume(volume podVolume) (*reconstructedVolume,
 		return nil, err
 	}
 	volumeSpec := reconstructed.Spec
+	if volumeSpec == nil {
+		return nil, fmt.Errorf("failed to reconstruct volume for plugin %q (spec.Name: %q) pod %q (UID: %q): got nil", volume.pluginName, volume.volumeSpecName, volume.podName, pod.UID)
+	}
 
 	// We have to find the plugins by volume spec (NOT by plugin name) here
 	// in order to correctly reconstruct ephemeral volume types.
@@ -312,9 +316,10 @@ func (rc *reconciler) reconstructVolume(volume podVolume) (*reconstructedVolume,
 		volumeGidValue:      "",
 		// devicePath is updated during updateStates() by checking node status's VolumesAttached data.
 		// TODO: get device path directly from the volume mount path.
-		devicePath:        "",
+		devicePath:          "",
-		mounter:           volumeMounter,
+		mounter:             volumeMounter,
-		blockVolumeMapper: volumeMapper,
+		blockVolumeMapper:   volumeMapper,
+		seLinuxMountContext: reconstructed.SELinuxMountContext,
 	}
 	return reconstructedVolume, nil
 }

pkg/kubelet/volumemanager/reconciler/reconstruct_new.go

@@ -112,6 +112,7 @@ func (rc *reconciler) updateStatesNew(reconstructedVolumes map[v1.UniqueVolumeNa
 			klog.ErrorS(err, "Could not add volume information to actual state of world", "volumeName", gvl.volumeName)
 			continue
 		}
+		var seLinuxMountContext string
 		for _, volume := range gvl.podVolumes {
 			markVolumeOpts := operationexecutor.MarkVolumeOpts{
 				PodName:             volume.podName,
@@ -123,6 +124,7 @@ func (rc *reconciler) updateStatesNew(reconstructedVolumes map[v1.UniqueVolumeNa
 				VolumeGidVolume:     volume.volumeGidValue,
 				VolumeSpec:          volume.volumeSpec,
 				VolumeMountState:    operationexecutor.VolumeMountUncertain,
+				SELinuxMountContext: volume.seLinuxMountContext,
 			}
 
 			_, err = rc.actualStateOfWorld.CheckAndMarkVolumeAsUncertainViaReconstruction(markVolumeOpts)
@@ -130,7 +132,8 @@ func (rc *reconciler) updateStatesNew(reconstructedVolumes map[v1.UniqueVolumeNa
 				klog.ErrorS(err, "Could not add pod to volume information to actual state of world", "pod", klog.KObj(volume.pod))
 				continue
 			}
-			klog.V(2).InfoS("Volume is marked as uncertain and added into the actual state", "pod", klog.KObj(volume.pod), "podName", volume.podName, "volumeName", volume.volumeName)
+			seLinuxMountContext = volume.seLinuxMountContext
+			klog.V(2).InfoS("Volume is marked as uncertain and added into the actual state", "pod", klog.KObj(volume.pod), "podName", volume.podName, "volumeName", volume.volumeName, "seLinuxMountContext", volume.seLinuxMountContext)
 		}
 		// If the volume has device to mount, we mark its device as uncertain.
 		if gvl.deviceMounter != nil || gvl.blockVolumeMapper != nil {
@@ -139,7 +142,7 @@ func (rc *reconciler) updateStatesNew(reconstructedVolumes map[v1.UniqueVolumeNa
 				klog.ErrorS(err, "Could not find device mount path for volume", "volumeName", gvl.volumeName)
 				continue
 			}
-			err = rc.actualStateOfWorld.MarkDeviceAsUncertain(gvl.volumeName, gvl.devicePath, deviceMountPath, "")
+			err = rc.actualStateOfWorld.MarkDeviceAsUncertain(gvl.volumeName, gvl.devicePath, deviceMountPath, seLinuxMountContext)
 			if err != nil {
 				klog.ErrorS(err, "Could not mark device is uncertain to actual state of world", "volumeName", gvl.volumeName, "deviceMountPath", deviceMountPath)
 				continue

pkg/volume/csi/csi_mounter_test.go

@@ -60,7 +60,7 @@ var (
 	testAccount = "test-service-account"
 )
 
-func prepareVolumeInfoFile(mountPath string, plug *csiPlugin, specVolumeName, volumeID, driverName, lifecycleMode string) error {
+func prepareVolumeInfoFile(mountPath string, plug *csiPlugin, specVolumeName, volumeID, driverName, lifecycleMode, seLinuxMountContext string) error {
 	nodeName := string(plug.host.GetNodeName())
 	volData := map[string]string{
 		volDataKey.specVolID:           specVolumeName,
@@ -69,6 +69,7 @@ func prepareVolumeInfoFile(mountPath string, plug *csiPlugin, specVolumeName, vo
 		volDataKey.nodeName:            nodeName,
 		volDataKey.attachmentID:        getAttachmentName(volumeID, driverName, nodeName),
 		volDataKey.volumeLifecycleMode: lifecycleMode,
+		volDataKey.seLinuxMountContext: seLinuxMountContext,
 	}
 	if err := os.MkdirAll(mountPath, 0755); err != nil {
 		return fmt.Errorf("failed to create dir for volume info file: %s", err)

pkg/volume/csi/csi_plugin.go

@@ -455,22 +455,23 @@ func (p *csiPlugin) ConstructVolumeSpec(volumeName, mountPath string) (volume.Re
 	if err != nil {
 		return volume.ReconstructedVolume{}, errors.New(log("plugin.ConstructVolumeSpec failed loading volume data using [%s]: %v", mountPath, err))
 	}
-
 	klog.V(4).Info(log("plugin.ConstructVolumeSpec extracted [%#v]", volData))
 
-	var spec *volume.Spec
+	var ret volume.ReconstructedVolume
+	if utilfeature.DefaultFeatureGate.Enabled(features.SELinuxMountReadWriteOncePod) {
+		ret.SELinuxMountContext = volData[volDataKey.seLinuxMountContext]
+	}
+
 	// If mode is VolumeLifecycleEphemeral, use constructVolSourceSpec
 	// to construct volume source spec. If mode is VolumeLifecyclePersistent,
 	// use constructPVSourceSpec to construct volume construct pv source spec.
 	if storage.VolumeLifecycleMode(volData[volDataKey.volumeLifecycleMode]) == storage.VolumeLifecycleEphemeral {
-		spec = p.constructVolSourceSpec(volData[volDataKey.specVolID], volData[volDataKey.driverName])
+		ret.Spec = p.constructVolSourceSpec(volData[volDataKey.specVolID], volData[volDataKey.driverName])
-		return volume.ReconstructedVolume{Spec: spec}, nil
+		return ret, nil
 	}
 
-	spec = p.constructPVSourceSpec(volData[volDataKey.specVolID], volData[volDataKey.driverName], volData[volDataKey.volHandle])
+	ret.Spec = p.constructPVSourceSpec(volData[volDataKey.specVolID], volData[volDataKey.driverName], volData[volDataKey.volHandle])
-	return volume.ReconstructedVolume{
+	return ret, nil
-		Spec: spec,
-	}, nil
 }
 
 // constructVolSourceSpec constructs volume.Spec with CSIVolumeSource

pkg/volume/csi/csi_plugin_test.go

@@ -29,9 +29,12 @@ import (
 	meta "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/wait"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	"k8s.io/client-go/informers"
 	fakeclient "k8s.io/client-go/kubernetes/fake"
 	utiltesting "k8s.io/client-go/util/testing"
+	featuregatetesting "k8s.io/component-base/featuregate/testing"
+	"k8s.io/kubernetes/pkg/features"
 	"k8s.io/kubernetes/pkg/volume"
 	volumetest "k8s.io/kubernetes/pkg/volume/testing"
 )
@@ -316,16 +319,20 @@ func TestPluginConstructVolumeSpec(t *testing.T) {
 	defer os.RemoveAll(tmpDir)
 
 	testCases := []struct {
-		name       string
+		name                      string
-		originSpec *volume.Spec
+		seLinuxMountEnabled       bool
-		specVolID  string
+		originSpec                *volume.Spec
-		volHandle  string
+		originSELinuxMountContext string
-		podUID     types.UID
+		specVolID                 string
+		volHandle                 string
+		expectedSELinuxContext    string
+		podUID                    types.UID
 	}{
 		{
-			name:       "construct spec1 from original persistent spec",
+			name:      "construct spec1 from original persistent spec",
-			specVolID:  "test.vol.id",
+			specVolID: "test.vol.id",
-			volHandle:  "testvol-handle1",
+			volHandle: "testvol-handle1",
+
 			originSpec: volume.NewSpecFromPersistentVolume(makeTestPV("test.vol.id", 20, testDriver, "testvol-handle1"), true),
 			podUID:     types.UID(fmt.Sprintf("%08X", rand.Uint64())),
 		},
@@ -336,12 +343,35 @@ func TestPluginConstructVolumeSpec(t *testing.T) {
 			originSpec: volume.NewSpecFromPersistentVolume(makeTestPV("spec2", 20, testDriver, "handle2"), true),
 			podUID:     types.UID(fmt.Sprintf("%08X", rand.Uint64())),
 		},
+		{
+			name:                      "construct SELinux context from original persistent spec when the feature is enabled",
+			seLinuxMountEnabled:       true,
+			specVolID:                 "spec3",
+			volHandle:                 "handle3",
+			originSELinuxMountContext: "system_u:object_r:container_file_t:s0:c314,c894",
+			originSpec:                volume.NewSpecFromPersistentVolume(makeTestPV("spec3", 20, testDriver, "handle3"), true),
+			expectedSELinuxContext:    "system_u:object_r:container_file_t:s0:c314,c894",
+			podUID:                    types.UID(fmt.Sprintf("%08X", rand.Uint64())),
+		},
+		{
+			name:                      "construct empty SELinux from original persistent spec when the feature is disabled",
+			seLinuxMountEnabled:       false,
+			specVolID:                 "spec4",
+			volHandle:                 "handle4",
+			originSELinuxMountContext: "system_u:object_r:container_file_t:s0:c314,c894",
+			originSpec:                volume.NewSpecFromPersistentVolume(makeTestPV("spec4", 20, testDriver, "handle4"), true),
+			expectedSELinuxContext:    "", // The context is cleared when the feature gate is off
+			podUID:                    types.UID(fmt.Sprintf("%08X", rand.Uint64())),
+		},
 	}
 
 	registerFakePlugin(testDriver, "endpoint", []string{"1.0.0"}, t)
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
+			defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.ReadWriteOncePod, tc.seLinuxMountEnabled)()
+			defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.SELinuxMountReadWriteOncePod, tc.seLinuxMountEnabled)()
+
 			mounter, err := plug.NewMounter(
 				tc.originSpec,
 				&api.Pod{ObjectMeta: meta.ObjectMeta{UID: tc.podUID, Namespace: testns}},
@@ -356,7 +386,7 @@ func TestPluginConstructVolumeSpec(t *testing.T) {
 			csiMounter := mounter.(*csiMountMgr)
 
 			mountPath := filepath.Dir(csiMounter.GetPath())
-			err = prepareVolumeInfoFile(mountPath, plug, tc.originSpec.Name(), csiMounter.volumeID, testDriver, string(csiMounter.volumeLifecycleMode))
+			err = prepareVolumeInfoFile(mountPath, plug, tc.originSpec.Name(), csiMounter.volumeID, testDriver, string(csiMounter.volumeLifecycleMode), tc.originSELinuxMountContext)
 			if err != nil {
 				t.Fatalf("failed to save fake volume info file: %s", err)
 			}
@@ -395,6 +425,10 @@ func TestPluginConstructVolumeSpec(t *testing.T) {
 			if rec.Spec.Name() != tc.specVolID {
 				t.Errorf("Unexpected spec name constructed %s", rec.Spec.Name())
 			}
+
+			if rec.SELinuxMountContext != tc.expectedSELinuxContext {
+				t.Errorf("Expected SELinux context %q, got %q", tc.expectedSELinuxContext, rec.SELinuxMountContext)
+			}
 		})
 	}
 }
@@ -490,7 +524,7 @@ func TestPluginConstructVolumeSpecWithInline(t *testing.T) {
 			csiMounter := mounter.(*csiMountMgr)
 
 			mountPath := filepath.Dir(csiMounter.GetPath())
-			err = prepareVolumeInfoFile(mountPath, plug, tc.originSpec.Name(), csiMounter.volumeID, testDriver, string(csiMounter.volumeLifecycleMode))
+			err = prepareVolumeInfoFile(mountPath, plug, tc.originSpec.Name(), csiMounter.volumeID, testDriver, string(csiMounter.volumeLifecycleMode), "")
 			if err != nil {
 				t.Fatalf("failed to save fake volume info file: %s", err)
 			}

pkg/volume/fc/fc.go

@@ -283,10 +283,25 @@ func (plugin *fcPlugin) ConstructVolumeSpec(volumeName, mountPath string) (volum
 			FC: &v1.FCVolumeSource{WWIDs: wwids, Lun: &lun, TargetWWNs: wwns},
 		},
 	}
+
+	var mountContext string
+	if utilfeature.DefaultFeatureGate.Enabled(features.SELinuxMountReadWriteOncePod) {
+		kvh, ok := plugin.host.(volume.KubeletVolumeHost)
+		if !ok {
+			return volume.ReconstructedVolume{}, fmt.Errorf("plugin volume host does not implement KubeletVolumeHost interface")
+		}
+		hu := kvh.GetHostUtil()
+		mountContext, err = hu.GetSELinuxMountContext(mountPath)
+		if err != nil {
+			return volume.ReconstructedVolume{}, err
+		}
+	}
+
 	klog.V(5).Infof("ConstructVolumeSpec: TargetWWNs: %v, Lun: %v, WWIDs: %v",
 		fcVolume.VolumeSource.FC.TargetWWNs, *fcVolume.VolumeSource.FC.Lun, fcVolume.VolumeSource.FC.WWIDs)
 	return volume.ReconstructedVolume{
-		Spec: volume.NewSpecFromVolume(fcVolume),
+		Spec:                volume.NewSpecFromVolume(fcVolume),
+		SELinuxMountContext: mountContext,
 	}, nil
 }
 

pkg/volume/iscsi/iscsi.go

@@ -279,8 +279,23 @@ func (plugin *iscsiPlugin) ConstructVolumeSpec(volumeName, mountPath string) (vo
 			},
 		},
 	}
+
+	var mountContext string
+	if utilfeature.DefaultFeatureGate.Enabled(features.SELinuxMountReadWriteOncePod) {
+		kvh, ok := plugin.host.(volume.KubeletVolumeHost)
+		if !ok {
+			return volume.ReconstructedVolume{}, fmt.Errorf("plugin volume host does not implement KubeletVolumeHost interface")
+		}
+		hu := kvh.GetHostUtil()
+		mountContext, err = hu.GetSELinuxMountContext(mountPath)
+		if err != nil {
+			return volume.ReconstructedVolume{}, err
+		}
+	}
+
 	return volume.ReconstructedVolume{
-		Spec: volume.NewSpecFromVolume(iscsiVolume),
+		Spec:                volume.NewSpecFromVolume(iscsiVolume),
+		SELinuxMountContext: mountContext,
 	}, nil
 }
 

pkg/volume/plugins.go

@@ -573,7 +573,11 @@ type VolumeConfig struct {
 // ReconstructedVolume contains information about a volume reconstructed by
 // ConstructVolumeSpec().
 type ReconstructedVolume struct {
+	// Spec is the volume spec of a mounted volume
 	Spec *Spec
+	// SELinuxMountContext is value of -o context=XYZ mount option.
+	// If empty, no such mount option is used.
+	SELinuxMountContext string
 }
 
 // NewSpecFromVolume creates an Spec from an v1.Volume

pkg/volume/rbd/rbd.go

@@ -430,8 +430,18 @@ func (plugin *rbdPlugin) ConstructVolumeSpec(volumeName, mountPath string) (volu
 			},
 		},
 	}
+
+	var mountContext string
+	if utilfeature.DefaultFeatureGate.Enabled(features.SELinuxMountReadWriteOncePod) {
+		mountContext, err = hu.GetSELinuxMountContext(mountPath)
+		if err != nil {
+			return volume.ReconstructedVolume{}, err
+		}
+	}
+
 	return volume.ReconstructedVolume{
-		Spec: volume.NewSpecFromVolume(rbdVolume),
+		Spec:                volume.NewSpecFromVolume(rbdVolume),
+		SELinuxMountContext: mountContext,
 	}, nil
 }
 

pkg/volume/util/hostutil/fake_hostutil.go

@@ -116,3 +116,9 @@ func (hu *FakeHostUtil) GetSELinuxSupport(pathname string) (bool, error) {
 func (hu *FakeHostUtil) GetMode(pathname string) (os.FileMode, error) {
 	return 0, errors.New("not implemented")
 }
+
+// GetSELinuxMountContext returns value of -o context=XYZ mount option on
+// given mount point.
+func (hu *FakeHostUtil) GetSELinuxMountContext(pathname string) (string, error) {
+	return "", errors.New("not implemented")
+}

pkg/volume/util/hostutil/hostutil.go

@@ -68,6 +68,9 @@ type HostUtils interface {
 	GetSELinuxSupport(pathname string) (bool, error)
 	// GetMode returns permissions of the path.
 	GetMode(pathname string) (os.FileMode, error)
+	// GetSELinuxMountContext returns value of -o context=XYZ mount option on
+	// given mount point.
+	GetSELinuxMountContext(pathname string) (string, error)
 }
 
 // Compile-time check to ensure all HostUtil implementations satisfy

pkg/volume/util/hostutil/hostutil_linux.go

@@ -299,3 +299,35 @@ func GetModeLinux(pathname string) (os.FileMode, error) {
 	}
 	return info.Mode(), nil
 }
+
+// GetSELinuxMountContext returns value of -o context=XYZ mount option on
+// given mount point.
+func (hu *HostUtil) GetSELinuxMountContext(pathname string) (string, error) {
+	return getSELinuxMountContext(pathname, procMountInfoPath, selinux.GetEnabled)
+}
+
+// getSELinux is common implementation of GetSELinuxSupport on Linux.
+// Using an extra function for unit tests.
+func getSELinuxMountContext(path string, mountInfoFilename string, selinuxEnabled seLinuxEnabledFunc) (string, error) {
+	// Skip /proc/mounts parsing if SELinux is disabled.
+	if !selinuxEnabled() {
+		return "", nil
+	}
+
+	info, err := findMountInfo(path, mountInfoFilename)
+	if err != nil {
+		return "", err
+	}
+
+	for _, opt := range info.SuperOptions {
+		if !strings.HasPrefix(opt, "context=") {
+			continue
+		}
+		// Remove context=
+		context := strings.TrimPrefix(opt, "context=")
+		// Remove double quotes
+		context = strings.Trim(context, "\"")
+		return context, nil
+	}
+	return "", nil
+}

pkg/volume/util/hostutil/hostutil_linux_test.go

@@ -331,3 +331,60 @@ func writeFile(content string) (string, string, error) {
 	}
 	return tempDir, filename, nil
 }
+
+func TestGetSELinuxMountContext(t *testing.T) {
+	info :=
+		`840 60 8:0 / /var/lib/kubelet/pods/d4f3b306-ad4c-4f7a-8983-b5b228039a8c/volumes/kubernetes.io~iscsi/mypv rw,relatime shared:421 - ext4 /dev/sda rw,context="system_u:object_r:container_file_t:s0:c314,c894"
+224 62 253:0 /var/lib/docker/devicemapper/test/shared /var/lib/docker/devicemapper/test/shared rw,relatime master:1 shared:44 - ext4 /dev/mapper/ssd-root rw,seclabel,data=ordered
+82 62 0:43 / /var/lib/foo rw,relatime shared:32 - tmpfs tmpfs rw
+83 63 0:44 / /var/lib/bar rw,relatime - tmpfs tmpfs rw
+`
+	tempDir, filename, err := writeFile(info)
+	if err != nil {
+		t.Fatalf("cannot create temporary file: %v", err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	tests := []struct {
+		name            string
+		mountPoint      string
+		seLinuxEnabled  bool
+		expectedContext string
+	}{
+		{
+			"no context",
+			"/var/lib/foo",
+			true,
+			"",
+		},
+		{
+			"with context with SELinux",
+			"/var/lib/kubelet/pods/d4f3b306-ad4c-4f7a-8983-b5b228039a8c/volumes/kubernetes.io~iscsi/mypv",
+			true,
+			"system_u:object_r:container_file_t:s0:c314,c894",
+		},
+		{
+			"with context with no SELinux",
+			"/var/lib/kubelet/pods/d4f3b306-ad4c-4f7a-8983-b5b228039a8c/volumes/kubernetes.io~iscsi/mypv",
+			false,
+			"",
+		},
+		{
+			"no context with seclabel",
+			"/var/lib/docker/devicemapper/test/shared",
+			true,
+			"",
+		},
+	}
+
+	for _, test := range tests {
+		out, err := getSELinuxMountContext(test.mountPoint, filename, func() bool { return test.seLinuxEnabled })
+		if err != nil {
+			t.Errorf("Test %s failed with error: %s", test.name, err)
+		}
+		if test.expectedContext != out {
+			t.Errorf("Test %s failed: expected %v, got %v", test.name, test.expectedContext, out)
+		}
+	}
+
+}

pkg/volume/util/hostutil/hostutil_unsupported.go

@@ -101,3 +101,9 @@ func (hu *HostUtil) GetMode(pathname string) (os.FileMode, error) {
 func getDeviceNameFromMount(mounter mount.Interface, mountPath, pluginMountDir string) (string, error) {
 	return "", errUnsupported
 }
+
+// GetSELinuxMountContext returns value of -o context=XYZ mount option on
+// given mount point.
+func (hu *HostUtil) GetSELinuxMountContext(pathname string) (string, error) {
+	return "", errUnsupported
+}

pkg/volume/util/hostutil/hostutil_windows.go

@@ -123,3 +123,9 @@ func (hu *HostUtil) GetMode(pathname string) (os.FileMode, error) {
 	}
 	return info.Mode(), nil
 }
+
+// GetSELinuxMountContext returns value of -o context=XYZ mount option on
+// given mount point.
+func (hu *HostUtil) GetSELinuxMountContext(pathname string) (string, error) {
+	return "", nil
+}