Include CSIDriver SupportsFsGroup

pkg/apis/storage/types.go

@@ -277,6 +277,14 @@ type CSIDriverSpec struct {
 	// +optional
 	AttachRequired *bool
 
+	// Defines if the underlying volume supports changing ownership and
+	// permission of the volume before being mounted.
+	// Refer to the specific FSGroupPolicy values for additional details.
+	// This field is alpha-level, and is only honored by servers
+	// that enable the CSIVolumeFSGroupPolicy feature gate.
+	// +optional
+	FSGroupPolicy *FSGroupPolicy
+
 	// If set to true, podInfoOnMount indicates this CSI volume driver
 	// requires additional pod information (like podName, podUID, etc.) during
 	// mount operations.
@@ -331,6 +339,37 @@ type CSIDriverSpec struct {
 	StorageCapacity *bool
 }
 
+// FSGroupPolicy specifies if a CSI Driver supports modifying
+// volume ownership and permissions of the volume to be mounted.
+// More modes may be added in the future.
+type FSGroupPolicy string
+
+const (
+	// ReadWriteOnceWithFSTypeFSGroupPolicy indicates that each volume will be examined
+	// to determine if the volume ownership and permissions
+	// should be modified. If a fstype is defined and the volume's access mode
+	// contains ReadWriteOnce, then the defined fsGroup will be applied.
+	// This mode should be defined if it's expected that the
+	// fsGroup may need to be modified depending on the pod's SecurityPolicy.
+	// This is the default behavior if no other FSGroupPolicy is defined.
+	ReadWriteOnceWithFSTypeFSGroupPolicy FSGroupPolicy = "ReadWriteOnceWithFSType"
+
+	// FileFSGroupPolicy indicates that CSI driver supports volume ownership
+	// and permission change via fsGroup, and Kubernetes may use fsGroup
+	// to change permissions and ownership of the volume to match user requested fsGroup in
+	// the pod's SecurityPolicy regardless of fstype or access mode.
+	// This mode should be defined if the fsGroup is expected to always change on mount
+	FileFSGroupPolicy FSGroupPolicy = "File"
+
+	// NoneFSGroupPolicy indicates that volumes will be mounted without performing
+	// any ownership or permission modifications, as the CSIDriver does not support
+	// these operations.
+	// This mode should be selected if the CSIDriver does not support fsGroup modifications,
+	// for example when Kubernetes cannot change ownership and permissions on a volume due
+	// to root-squash settings on a NFS volume.
+	NoneFSGroupPolicy FSGroupPolicy = "None"
+)
+
 // VolumeLifecycleMode specifies how a CSI volume is used in Kubernetes.
 // More modes may be added in the future.
 type VolumeLifecycleMode string

pkg/apis/storage/v1/defaults.go

@@ -53,6 +53,10 @@ func SetDefaults_CSIDriver(obj *storagev1.CSIDriver) {
 		obj.Spec.StorageCapacity = new(bool)
 		*(obj.Spec.StorageCapacity) = false
 	}
+	if obj.Spec.FSGroupPolicy == nil && utilfeature.DefaultFeatureGate.Enabled(features.CSIVolumeFSGroupPolicy) {
+		obj.Spec.FSGroupPolicy = new(storagev1.FSGroupPolicy)
+		*obj.Spec.FSGroupPolicy = storagev1.ReadWriteOnceWithFSTypeFSGroupPolicy
+	}
 	if len(obj.Spec.VolumeLifecycleModes) == 0 && utilfeature.DefaultFeatureGate.Enabled(features.CSIInlineVolume) {
 		obj.Spec.VolumeLifecycleModes = append(obj.Spec.VolumeLifecycleModes, storagev1.VolumeLifecyclePersistent)
 	}

pkg/apis/storage/v1beta1/defaults.go

@@ -17,7 +17,7 @@ limitations under the License.
 package v1beta1
 
 import (
-	"k8s.io/api/core/v1"
+	v1 "k8s.io/api/core/v1"
 	storagev1beta1 "k8s.io/api/storage/v1beta1"
 	"k8s.io/apimachinery/pkg/runtime"
 	utilfeature "k8s.io/apiserver/pkg/util/feature"
@@ -53,6 +53,10 @@ func SetDefaults_CSIDriver(obj *storagev1beta1.CSIDriver) {
 		obj.Spec.StorageCapacity = new(bool)
 		*(obj.Spec.StorageCapacity) = false
 	}
+	if obj.Spec.FSGroupPolicy == nil && utilfeature.DefaultFeatureGate.Enabled(features.CSIVolumeFSGroupPolicy) {
+		obj.Spec.FSGroupPolicy = new(storagev1beta1.FSGroupPolicy)
+		*obj.Spec.FSGroupPolicy = storagev1beta1.ReadWriteOnceWithFSTypeFSGroupPolicy
+	}
 	if len(obj.Spec.VolumeLifecycleModes) == 0 && utilfeature.DefaultFeatureGate.Enabled(features.CSIInlineVolume) {
 		obj.Spec.VolumeLifecycleModes = append(obj.Spec.VolumeLifecycleModes, storagev1beta1.VolumeLifecyclePersistent)
 	}

pkg/apis/storage/validation/validation.go

@@ -421,6 +421,7 @@ func validateCSIDriverSpec(
 	allErrs = append(allErrs, validateAttachRequired(spec.AttachRequired, fldPath.Child("attachedRequired"))...)
 	allErrs = append(allErrs, validatePodInfoOnMount(spec.PodInfoOnMount, fldPath.Child("podInfoOnMount"))...)
 	allErrs = append(allErrs, validateStorageCapacity(spec.StorageCapacity, fldPath.Child("storageCapacity"))...)
+	allErrs = append(allErrs, validateFSGroupPolicy(spec.FSGroupPolicy, fldPath.Child("fsGroupPolicy"))...)
 	allErrs = append(allErrs, validateVolumeLifecycleModes(spec.VolumeLifecycleModes, fldPath.Child("volumeLifecycleModes"))...)
 	return allErrs
 }
@@ -451,6 +452,21 @@ func validateStorageCapacity(storageCapacity *bool, fldPath *field.Path) field.E
 	if storageCapacity == nil && utilfeature.DefaultFeatureGate.Enabled(features.CSIStorageCapacity) {
 		allErrs = append(allErrs, field.Required(fldPath, ""))
 	}
+}
+
+var supportedFSGroupPolicy = sets.NewString(string(storage.ReadWriteOnceWithFSTypeFSGroupPolicy), string(storage.FileFSGroupPolicy), string(storage.NoneFSGroupPolicy))
+
+// validateFSGroupPolicy tests if FSGroupPolicy contains an appropriate value.
+func validateFSGroupPolicy(fsGroupPolicy *storage.FSGroupPolicy, fldPath *field.Path) field.ErrorList {
+	allErrs := field.ErrorList{}
+	if fsGroupPolicy == nil {
+		// This is not a required field, so if nothing is provided simply return
+		return allErrs
+	}
+
+	if !supportedFSGroupPolicy.Has(string(*fsGroupPolicy)) {
+		allErrs = append(allErrs, field.NotSupported(fldPath, fsGroupPolicy, supportedFSGroupPolicy.List()))
+	}
 
 	return allErrs
 }

pkg/apis/storage/validation/validation_test.go

@@ -1665,6 +1665,9 @@ func TestCSIDriverValidation(t *testing.T) {
 	attachNotRequired := false
 	podInfoOnMount := true
 	notPodInfoOnMount := false
+	supportedFSGroupPolicy := storage.FileFSGroupPolicy
+	invalidFSGroupPolicy := storage.ReadWriteOnceWithFSTypeFSGroupPolicy
+	invalidFSGroupPolicy = "invalid-mode"
 	successCases := []storage.CSIDriver{
 		{
 			ObjectMeta: metav1.ObjectMeta{Name: driverName},
@@ -1769,6 +1772,14 @@ func TestCSIDriverValidation(t *testing.T) {
 				},
 			},
 		},
+		{
+			ObjectMeta: metav1.ObjectMeta{Name: driverName},
+			Spec: storage.CSIDriverSpec{
+				AttachRequired: &attachNotRequired,
+				PodInfoOnMount: &notPodInfoOnMount,
+				FSGroupPolicy:  &supportedFSGroupPolicy,
+			},
+		},
 	}
 
 	for _, csiDriver := range successCases {
@@ -1818,6 +1829,15 @@ func TestCSIDriverValidation(t *testing.T) {
 				},
 			},
 		},
+		{
+			// invalid fsGroupPolicy
+			ObjectMeta: metav1.ObjectMeta{Name: driverName},
+			Spec: storage.CSIDriverSpec{
+				AttachRequired: &attachNotRequired,
+				PodInfoOnMount: &notPodInfoOnMount,
+				FSGroupPolicy:  &invalidFSGroupPolicy,
+			},
+		},
 	}
 
 	for _, csiDriver := range errorCases {