add gc admission plugin that prevents user who doesn't have delete permission of…

cmd/kube-apiserver/app/server.go

@@ -384,7 +384,9 @@ func BuildAdmission(s *options.ServerRunOptions, plugins *admission.Plugins, cli
 			glog.Fatalf("Error reading from cloud configuration file %s: %#v", s.CloudProvider.CloudConfigFile, err)
 		}
 	}
-	pluginInitializer := kubeapiserveradmission.NewPluginInitializer(client, sharedInformers, apiAuthorizer, cloudConfig)
+	// TODO: use a dynamic restmapper. See https://github.com/kubernetes/kubernetes/pull/42615.
+	restMapper := api.Registry.RESTMapper()
+	pluginInitializer := kubeapiserveradmission.NewPluginInitializer(client, sharedInformers, apiAuthorizer, cloudConfig, restMapper)
 	admissionConfigProvider, err := admission.ReadAdmissionConfiguration(admissionControlPluginNames, s.GenericServerRunOptions.AdmissionControlConfigFile)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read plugin config: %v", err)

federation/cmd/federation-apiserver/app/server.go

@@ -194,7 +194,7 @@ func NonBlockingRun(s *options.ServerRunOptions, stopCh <-chan struct{}) error {
 			glog.Fatalf("Error reading from cloud configuration file %s: %#v", s.CloudProvider.CloudConfigFile, err)
 		}
 	}
-	pluginInitializer := kubeapiserveradmission.NewPluginInitializer(client, sharedInformers, apiAuthorizer, cloudConfig)
+	pluginInitializer := kubeapiserveradmission.NewPluginInitializer(client, sharedInformers, apiAuthorizer, cloudConfig, nil)
 	admissionConfigProvider, err := admission.ReadAdmissionConfiguration(admissionControlPluginNames, s.GenericServerRunOptions.AdmissionControlConfigFile)
 	if err != nil {
 		return fmt.Errorf("failed to read plugin config: %v", err)

pkg/kubeapiserver/admission/BUILD

@@ -29,6 +29,7 @@ go_library(
     deps = [
         "//pkg/client/clientset_generated/internalclientset:go_default_library",
         "//pkg/client/informers/informers_generated/internalversion:go_default_library",
+        "//vendor:k8s.io/apimachinery/pkg/api/meta",
         "//vendor:k8s.io/apiserver/pkg/admission",
         "//vendor:k8s.io/apiserver/pkg/authorization/authorizer",
     ],

pkg/kubeapiserver/admission/init_test.go

@@ -51,7 +51,7 @@ var _ WantsAuthorizer = &WantAuthorizerAdmission{}
 // TestWantsAuthorizer ensures that the authorizer is injected when the WantsAuthorizer
 // interface is implemented.
 func TestWantsAuthorizer(t *testing.T) {
-	initializer := NewPluginInitializer(nil, nil, &TestAuthorizer{}, nil)
+	initializer := NewPluginInitializer(nil, nil, &TestAuthorizer{}, nil, nil)
 	wantAuthorizerAdmission := &WantAuthorizerAdmission{}
 	initializer.Initialize(wantAuthorizerAdmission)
 	if wantAuthorizerAdmission.auth == nil {
@@ -73,7 +73,7 @@ func (self *WantsCloudConfigAdmissionPlugin) Validate() error
 
 func TestCloudConfigAdmissionPlugin(t *testing.T) {
 	cloudConfig := []byte("cloud-configuration")
-	initializer := NewPluginInitializer(nil, nil, &TestAuthorizer{}, cloudConfig)
+	initializer := NewPluginInitializer(nil, nil, &TestAuthorizer{}, cloudConfig, nil)
 	wantsCloudConfigAdmission := &WantsCloudConfigAdmissionPlugin{}
 	initializer.Initialize(wantsCloudConfigAdmission)
 

pkg/kubeapiserver/admission/initializer.go

@@ -17,6 +17,7 @@ limitations under the License.
 package admission
 
 import (
+	"k8s.io/apimachinery/pkg/api/meta"
 	"k8s.io/apiserver/pkg/admission"
 	"k8s.io/apiserver/pkg/authorization/authorizer"
 	"k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset"
@@ -48,22 +49,29 @@ type WantsCloudConfig interface {
 	SetCloudConfig([]byte)
 }
 
+// WantsRESTMapper defines a function which sets RESTMapper for admission plugins that need it.
+type WantsRESTMapper interface {
+	SetRESTMapper(meta.RESTMapper)
+}
+
 type pluginInitializer struct {
 	internalClient internalclientset.Interface
 	informers      informers.SharedInformerFactory
 	authorizer     authorizer.Authorizer
 	cloudConfig    []byte
+	restMapper     meta.RESTMapper
 }
 
 var _ admission.PluginInitializer = pluginInitializer{}
 
 // NewPluginInitializer constructs new instance of PluginInitializer
-func NewPluginInitializer(internalClient internalclientset.Interface, sharedInformers informers.SharedInformerFactory, authz authorizer.Authorizer, cloudConfig []byte) admission.PluginInitializer {
+func NewPluginInitializer(internalClient internalclientset.Interface, sharedInformers informers.SharedInformerFactory, authz authorizer.Authorizer, cloudConfig []byte, restMapper meta.RESTMapper) admission.PluginInitializer {
 	return pluginInitializer{
 		internalClient: internalClient,
 		informers:      sharedInformers,
 		authorizer:     authz,
 		cloudConfig:    cloudConfig,
+		restMapper:     restMapper,
 	}
 }
 
@@ -85,4 +93,8 @@ func (i pluginInitializer) Initialize(plugin admission.Interface) {
 	if wants, ok := plugin.(WantsCloudConfig); ok {
 		wants.SetCloudConfig(i.cloudConfig)
 	}
+
+	if wants, ok := plugin.(WantsRESTMapper); ok {
+		wants.SetRESTMapper(i.restMapper)
+	}
 }

plugin/pkg/admission/gc/BUILD

@@ -16,7 +16,10 @@ go_library(
         "//pkg/kubeapiserver/admission:go_default_library",
         "//vendor:k8s.io/apimachinery/pkg/api/equality",
         "//vendor:k8s.io/apimachinery/pkg/api/meta",
+        "//vendor:k8s.io/apimachinery/pkg/apis/meta/v1",
         "//vendor:k8s.io/apimachinery/pkg/runtime",
+        "//vendor:k8s.io/apimachinery/pkg/runtime/schema",
+        "//vendor:k8s.io/apimachinery/pkg/types",
         "//vendor:k8s.io/apiserver/pkg/admission",
         "//vendor:k8s.io/apiserver/pkg/authorization/authorizer",
     ],
@@ -29,6 +32,7 @@ go_test(
     tags = ["automanaged"],
     deps = [
         "//pkg/api:go_default_library",
+        "//pkg/kubeapiserver/admission:go_default_library",
         "//vendor:k8s.io/apimachinery/pkg/apis/meta/v1",
         "//vendor:k8s.io/apimachinery/pkg/runtime",
         "//vendor:k8s.io/apimachinery/pkg/runtime/schema",

plugin/pkg/admission/gc/gc_admission.go

@@ -22,7 +22,10 @@ import (
 
 	apiequality "k8s.io/apimachinery/pkg/api/equality"
 	"k8s.io/apimachinery/pkg/api/meta"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apiserver/pkg/admission"
 	"k8s.io/apiserver/pkg/authorization/authorizer"
 	kubeapiserveradmission "k8s.io/kubernetes/pkg/kubeapiserver/admission"
@@ -41,6 +44,8 @@ type gcPermissionsEnforcement struct {
 	*admission.Handler
 
 	authorizer authorizer.Authorizer
+
+	restMapper meta.RESTMapper
 }
 
 func (a *gcPermissionsEnforcement) Admit(attributes admission.Attributes) (err error) {
@@ -62,11 +67,32 @@ func (a *gcPermissionsEnforcement) Admit(attributes admission.Attributes) (err e
 		Path:            "",
 	}
 	allowed, reason, err := a.authorizer.Authorize(deleteAttributes)
-	if allowed {
-		return nil
+	if !allowed {
+		return admission.NewForbidden(attributes, fmt.Errorf("cannot set an ownerRef on a resource you can't delete: %v, %v", reason, err))
+	}
+
+	// Further check if the user is setting ownerReference.blockOwnerDeletion to
+	// true. If so, only allows the change if the user has delete permission of
+	// the _OWNER_
+	newBlockingRefs := newBlockingOwnerDeletionRefs(attributes.GetObject(), attributes.GetOldObject())
+	for _, ref := range newBlockingRefs {
+		records, err := a.ownerRefToDeleteAttributeRecords(ref, attributes)
+		if err != nil {
+			return admission.NewForbidden(attributes, fmt.Errorf("cannot set blockOwnerDeletion in this case because cannot find RESTMapping for APIVersion %s Kind %s: %v, %v", ref.APIVersion, ref.Kind, reason, err))
+		}
+		// Multiple records are returned if ref.Kind could map to multiple
+		// resources. User needs to have delete permission on all the
+		// matched Resources.
+		for _, record := range records {
+			allowed, reason, err := a.authorizer.Authorize(record)
+			if !allowed {
+				return admission.NewForbidden(attributes, fmt.Errorf("cannot set blockOwnerDeletion if an ownerReference refers to a resource you can't delete: %v, %v", reason, err))
+			}
+		}
 	}
 
-	return admission.NewForbidden(attributes, fmt.Errorf("cannot set an ownerRef on a resource you can't delete: %v, %v", reason, err))
+	return nil
+
 }
 
 func isChangingOwnerReference(newObj, oldObj runtime.Object) bool {
@@ -100,13 +126,109 @@ func isChangingOwnerReference(newObj, oldObj runtime.Object) bool {
 	return false
 }
 
+// Translates ref to a DeleteAttribute deleting the object referred by the ref.
+// OwnerReference only records the object kind, which might map to multiple
+// resources, so multiple DeleteAttribute might be returned.
+func (a *gcPermissionsEnforcement) ownerRefToDeleteAttributeRecords(ref metav1.OwnerReference, attributes admission.Attributes) ([]authorizer.AttributesRecord, error) {
+	var ret []authorizer.AttributesRecord
+	groupVersion, err := schema.ParseGroupVersion(ref.APIVersion)
+	if err != nil {
+		return ret, err
+	}
+	mappings, err := a.restMapper.RESTMappings(schema.GroupKind{Group: groupVersion.Group, Kind: ref.Kind}, groupVersion.Version)
+	if err != nil {
+		return ret, err
+	}
+	for _, mapping := range mappings {
+		ret = append(ret, authorizer.AttributesRecord{
+			User: attributes.GetUserInfo(),
+			Verb: "delete",
+			// ownerReference can only refer to an object in the same namespace, so attributes.GetNamespace() equals to the owner's namespace
+			Namespace:       attributes.GetNamespace(),
+			APIGroup:        groupVersion.Group,
+			APIVersion:      groupVersion.Version,
+			Resource:        mapping.Resource,
+			Name:            ref.Name,
+			ResourceRequest: true,
+			Path:            "",
+		})
+	}
+	return ret, nil
+}
+
+// only keeps the blocking refs
+func blockingOwnerRefs(refs []metav1.OwnerReference) []metav1.OwnerReference {
+	var ret []metav1.OwnerReference
+	for _, ref := range refs {
+		if ref.BlockOwnerDeletion != nil && *ref.BlockOwnerDeletion == true {
+			ret = append(ret, ref)
+		}
+	}
+	return ret
+}
+
+func indexByUID(refs []metav1.OwnerReference) map[types.UID]metav1.OwnerReference {
+	ret := make(map[types.UID]metav1.OwnerReference)
+	for _, ref := range refs {
+		ret[ref.UID] = ref
+	}
+	return ret
+}
+
+// Returns new blocking ownerReferences, and references whose blockOwnerDeletion
+// field is changed from nil or false to true.
+func newBlockingOwnerDeletionRefs(newObj, oldObj runtime.Object) []metav1.OwnerReference {
+	newMeta, err := meta.Accessor(newObj)
+	if err != nil {
+		// if we don't have objectmeta, we don't have the object reference
+		return nil
+	}
+	newRefs := newMeta.GetOwnerReferences()
+	blockingNewRefs := blockingOwnerRefs(newRefs)
+	if len(blockingNewRefs) == 0 {
+		return nil
+	}
+
+	if oldObj == nil {
+		return blockingNewRefs
+	}
+	oldMeta, err := meta.Accessor(oldObj)
+	if err != nil {
+		// if we don't have objectmeta, treat it as if all the ownerReference are newly created
+		return blockingNewRefs
+	}
+
+	var ret []metav1.OwnerReference
+	indexedOldRefs := indexByUID(oldMeta.GetOwnerReferences())
+	for _, ref := range blockingNewRefs {
+		oldRef, ok := indexedOldRefs[ref.UID]
+		if !ok {
+			// if ref is newly added, and it's blocking, then returns it.
+			ret = append(ret, ref)
+			continue
+		}
+		wasNotBlocking := oldRef.BlockOwnerDeletion == nil || *oldRef.BlockOwnerDeletion == false
+		if wasNotBlocking {
+			ret = append(ret, ref)
+		}
+	}
+	return ret
+}
+
 func (a *gcPermissionsEnforcement) SetAuthorizer(authorizer authorizer.Authorizer) {
 	a.authorizer = authorizer
 }
 
+func (a *gcPermissionsEnforcement) SetRESTMapper(restMapper meta.RESTMapper) {
+	a.restMapper = restMapper
+}
+
 func (a *gcPermissionsEnforcement) Validate() error {
 	if a.authorizer == nil {
 		return fmt.Errorf("missing authorizer")
 	}
+	if a.restMapper == nil {
+		return fmt.Errorf("missing restMapper")
+	}
 	return nil
 }

plugin/pkg/admission/limitranger/admission_test.go

@@ -595,7 +595,7 @@ func newHandlerForTest(c clientset.Interface) (admission.Interface, informers.Sh
 	if err != nil {
 		return nil, f, err
 	}
-	pluginInitializer := kubeadmission.NewPluginInitializer(c, f, nil, nil)
+	pluginInitializer := kubeadmission.NewPluginInitializer(c, f, nil, nil, nil)
 	pluginInitializer.Initialize(handler)
 	err = admission.Validate(handler)
 	return handler, f, err

plugin/pkg/admission/namespace/autoprovision/admission_test.go

@@ -38,7 +38,7 @@ import (
 func newHandlerForTest(c clientset.Interface) (admission.Interface, informers.SharedInformerFactory, error) {
 	f := informers.NewSharedInformerFactory(c, 5*time.Minute)
 	handler := NewProvision()
-	pluginInitializer := kubeadmission.NewPluginInitializer(c, f, nil, nil)
+	pluginInitializer := kubeadmission.NewPluginInitializer(c, f, nil, nil, nil)
 	pluginInitializer.Initialize(handler)
 	err := admission.Validate(handler)
 	return handler, f, err

plugin/pkg/admission/namespace/exists/admission_test.go

@@ -37,7 +37,7 @@ import (
 func newHandlerForTest(c clientset.Interface) (admission.Interface, informers.SharedInformerFactory, error) {
 	f := informers.NewSharedInformerFactory(c, 5*time.Minute)
 	handler := NewExists()
-	pluginInitializer := kubeadmission.NewPluginInitializer(c, f, nil, nil)
+	pluginInitializer := kubeadmission.NewPluginInitializer(c, f, nil, nil, nil)
 	pluginInitializer.Initialize(handler)
 	err := admission.Validate(handler)
 	return handler, f, err

plugin/pkg/admission/namespace/lifecycle/admission_test.go

@@ -48,7 +48,7 @@ func newHandlerForTestWithClock(c clientset.Interface, cacheClock clock.Clock) (
 	if err != nil {
 		return nil, f, err
 	}
-	pluginInitializer := kubeadmission.NewPluginInitializer(c, f, nil, nil)
+	pluginInitializer := kubeadmission.NewPluginInitializer(c, f, nil, nil, nil)
 	pluginInitializer.Initialize(handler)
 	err = admission.Validate(handler)
 	return handler, f, err

plugin/pkg/admission/podnodeselector/admission_test.go

@@ -183,7 +183,7 @@ func TestHandles(t *testing.T) {
 func newHandlerForTest(c clientset.Interface) (*podNodeSelector, informers.SharedInformerFactory, error) {
 	f := informers.NewSharedInformerFactory(c, 5*time.Minute)
 	handler := NewPodNodeSelector(nil)
-	pluginInitializer := kubeadmission.NewPluginInitializer(c, f, nil, nil)
+	pluginInitializer := kubeadmission.NewPluginInitializer(c, f, nil, nil, nil)
 	pluginInitializer.Initialize(handler)
 	err := admission.Validate(handler)
 	return handler, f, err

plugin/pkg/admission/podtolerationrestriction/admission_test.go

@@ -193,7 +193,7 @@ func newHandlerForTest(c clientset.Interface) (*podTolerationsPlugin, informers.
 		return nil, nil, err
 	}
 	handler := NewPodTolerationsPlugin(pluginConfig)
-	pluginInitializer := kubeadmission.NewPluginInitializer(c, f, nil, nil)
+	pluginInitializer := kubeadmission.NewPluginInitializer(c, f, nil, nil, nil)
 	pluginInitializer.Initialize(handler)
 	err = admission.Validate(handler)
 	return handler, f, err