Merge pull request #118356 from ritazh/ec-admission

Add ephemeralcontainer to imagepolicy securityaccount admission plugin

plugin/pkg/admission/imagepolicy/admission.go

@@ -46,6 +46,7 @@ import (
 
 // PluginName indicates name of admission plugin.
 const PluginName = "ImagePolicyWebhook"
+const ephemeralcontainers = "ephemeralcontainers"
 
 // AuditKeyPrefix is used as the prefix for all audit keys handled by this
 // pluggin. Some well known suffixes are listed below.
@@ -132,8 +133,9 @@ func (a *Plugin) webhookError(pod *api.Pod, attributes admission.Attributes, err
 
 // Validate makes an admission decision based on the request attributes
 func (a *Plugin) Validate(ctx context.Context, attributes admission.Attributes, o admission.ObjectInterfaces) (err error) {
-	// Ignore all calls to subresources or resources other than pods.
+	// Ignore all calls to subresources other than ephemeralcontainers or calls to resources other than pods.
-	if attributes.GetSubresource() != "" || attributes.GetResource().GroupResource() != api.Resource("pods") {
+	subresource := attributes.GetSubresource()
+	if (subresource != "" && subresource != ephemeralcontainers) || attributes.GetResource().GroupResource() != api.Resource("pods") {
 		return nil
 	}
 
@@ -144,6 +146,7 @@ func (a *Plugin) Validate(ctx context.Context, attributes admission.Attributes,
 
 	// Build list of ImageReviewContainerSpec
 	var imageReviewContainerSpecs []v1alpha1.ImageReviewContainerSpec
+	if subresource == "" {
 		containers := make([]api.Container, 0, len(pod.Spec.Containers)+len(pod.Spec.InitContainers))
 		containers = append(containers, pod.Spec.Containers...)
 		containers = append(containers, pod.Spec.InitContainers...)
@@ -152,6 +155,13 @@ func (a *Plugin) Validate(ctx context.Context, attributes admission.Attributes,
 				Image: c.Image,
 			})
 		}
+	} else if subresource == ephemeralcontainers {
+		for _, c := range pod.Spec.EphemeralContainers {
+			imageReviewContainerSpecs = append(imageReviewContainerSpecs, v1alpha1.ImageReviewContainerSpec{
+				Image: c.Image,
+			})
+		}
+	}
 	imageReview := v1alpha1.ImageReview{
 		Spec: v1alpha1.ImageReviewSpec{
 			Containers:  imageReviewContainerSpecs,

plugin/pkg/admission/imagepolicy/admission_test.go

@@ -39,7 +39,6 @@ import (
 	api "k8s.io/kubernetes/pkg/apis/core"
 
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"text/template"
@@ -94,7 +93,7 @@ func TestNewFromConfig(t *testing.T) {
 		{data.Key, clientKey},
 	}
 	for _, file := range files {
-		if err := ioutil.WriteFile(file.name, file.data, 0400); err != nil {
+		if err := os.WriteFile(file.name, file.data, 0400); err != nil {
 			t.Fatal(err)
 		}
 	}
@@ -198,10 +197,11 @@ current-context: default
 		// Use a closure so defer statements trigger between loop iterations.
 		t.Run(tt.msg, func(t *testing.T) {
 			err := func() error {
-				tempfile, err := ioutil.TempFile("", "")
+				tempfile, err := os.CreateTemp("", "")
 				if err != nil {
 					return err
 				}
+				p := tempfile.Name()
 				defer utiltesting.CloseAndRemove(t, tempfile)
 
 				tmpl, err := template.New("test").Parse(tt.kubeConfigTmpl)
@@ -212,11 +212,12 @@ current-context: default
 					return fmt.Errorf("failed to execute test template: %v", err)
 				}
 
-				tempconfigfile, err := ioutil.TempFile("", "")
+				tempconfigfile, err := os.CreateTemp("", "")
 				if err != nil {
 					return err
 				}
-				defer os.Remove(tempconfigfile.Name())
+				pc := tempconfigfile.Name()
+				defer utiltesting.CloseAndRemove(t, tempconfigfile)
 
 				configTmpl, err := template.New("testconfig").Parse(defaultConfigTmplJSON)
 				if err != nil {
@@ -229,7 +230,7 @@ current-context: default
 					RetryBackoff int
 					DefaultAllow bool
 				}{
-					KubeConfig:   tempfile.Name(),
+					KubeConfig:   p,
 					AllowTTL:     500,
 					DenyTTL:      500,
 					RetryBackoff: 500,
@@ -240,7 +241,7 @@ current-context: default
 				}
 
 				// Create a new admission controller
-				configFile, err := os.Open(tempconfigfile.Name())
+				configFile, err := os.Open(pc)
 				if err != nil {
 					return fmt.Errorf("failed to read test config: %v", err)
 				}
@@ -358,13 +359,13 @@ func (m *mockService) HTTPStatusCode() int { return m.statusCode }
 
 // newImagePolicyWebhook creates a temporary kubeconfig file from the provided arguments and attempts to load
 // a new newImagePolicyWebhook from it.
-func newImagePolicyWebhook(t *testing.T, callbackURL string, clientCert, clientKey, ca []byte, cacheTime time.Duration, defaultAllow bool) (*Plugin, error) {
+func newImagePolicyWebhook(callbackURL string, clientCert, clientKey, ca []byte, cacheTime time.Duration, defaultAllow bool) (*Plugin, error) {
-	tempfile, err := ioutil.TempFile("", "")
+	tempfile, err := os.CreateTemp("", "")
 	if err != nil {
 		return nil, err
 	}
 	p := tempfile.Name()
-	defer utiltesting.CloseAndRemove(t, tempfile)
+	defer os.Remove(p)
 	config := v1.Config{
 		Clusters: []v1.NamedCluster{
 			{
@@ -381,12 +382,12 @@ func newImagePolicyWebhook(t *testing.T, callbackURL string, clientCert, clientK
 		return nil, err
 	}
 
-	tempconfigfile, err := ioutil.TempFile("", "")
+	tempconfigfile, err := os.CreateTemp("", "")
 	if err != nil {
 		return nil, err
 	}
 	pc := tempconfigfile.Name()
-	defer utiltesting.CloseAndRemove(t, tempconfigfile)
+	defer os.Remove(pc)
 
 	configTmpl, err := template.New("testconfig").Parse(defaultConfigTmplYAML)
 	if err != nil {
@@ -478,7 +479,7 @@ func TestTLSConfig(t *testing.T) {
 			}
 			defer server.Close()
 
-			wh, err := newImagePolicyWebhook(t, server.URL, tt.clientCert, tt.clientKey, tt.clientCA, -1, false)
+			wh, err := newImagePolicyWebhook(server.URL, tt.clientCert, tt.clientKey, tt.clientCA, -1, false)
 			if err != nil {
 				t.Errorf("%s: failed to create client: %v", tt.test, err)
 				return
@@ -559,7 +560,7 @@ func TestWebhookCache(t *testing.T) {
 	defer s.Close()
 
 	// Create an admission controller that caches successful responses.
-	wh, err := newImagePolicyWebhook(t, s.URL, clientCert, clientKey, caCert, 200, false)
+	wh, err := newImagePolicyWebhook(s.URL, clientCert, clientKey, caCert, 200, false)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -595,17 +596,23 @@ func TestContainerCombinations(t *testing.T) {
 		test                 string
 		pod                  *api.Pod
 		wantAllowed, wantErr bool
+		subresource          string
+		operation            admission.Operation
 	}{
 		{
 			test:        "Single container allowed",
 			pod:         goodPod("good"),
 			wantAllowed: true,
+			subresource: "",
+			operation:   admission.Create,
 		},
 		{
 			test:        "Single container denied",
 			pod:         goodPod("bad"),
 			wantAllowed: false,
 			wantErr:     true,
+			subresource: "",
+			operation:   admission.Create,
 		},
 		{
 			test: "One good container, one bad",
@@ -627,6 +634,8 @@ func TestContainerCombinations(t *testing.T) {
 			},
 			wantAllowed: false,
 			wantErr:     true,
+			subresource: "",
+			operation:   admission.Create,
 		},
 		{
 			test: "Multiple good containers",
@@ -648,6 +657,8 @@ func TestContainerCombinations(t *testing.T) {
 			},
 			wantAllowed: true,
 			wantErr:     false,
+			subresource: "",
+			operation:   admission.Create,
 		},
 		{
 			test: "Multiple bad containers",
@@ -669,6 +680,8 @@ func TestContainerCombinations(t *testing.T) {
 			},
 			wantAllowed: false,
 			wantErr:     true,
+			subresource: "",
+			operation:   admission.Create,
 		},
 		{
 			test: "Good container, bad init container",
@@ -692,6 +705,8 @@ func TestContainerCombinations(t *testing.T) {
 			},
 			wantAllowed: false,
 			wantErr:     true,
+			subresource: "",
+			operation:   admission.Create,
 		},
 		{
 			test: "Bad container, good init container",
@@ -715,6 +730,8 @@ func TestContainerCombinations(t *testing.T) {
 			},
 			wantAllowed: false,
 			wantErr:     true,
+			subresource: "",
+			operation:   admission.Create,
 		},
 		{
 			test: "Good container, good init container",
@@ -738,6 +755,123 @@ func TestContainerCombinations(t *testing.T) {
 			},
 			wantAllowed: true,
 			wantErr:     false,
+			subresource: "",
+			operation:   admission.Create,
+		},
+		{
+			test: "Good container, good init container, bad ephemeral container when updating ephemeralcontainers subresource",
+			pod: &api.Pod{
+				Spec: api.PodSpec{
+					ServiceAccountName: "default",
+					SecurityContext:    &api.PodSecurityContext{},
+					Containers: []api.Container{
+						{
+							Image:           "good",
+							SecurityContext: &api.SecurityContext{},
+						},
+					},
+					InitContainers: []api.Container{
+						{
+							Image:           "good",
+							SecurityContext: &api.SecurityContext{},
+						},
+					},
+					EphemeralContainers: []api.EphemeralContainer{
+						{
+							EphemeralContainerCommon: api.EphemeralContainerCommon{
+								Image:           "bad",
+								SecurityContext: &api.SecurityContext{},
+							},
+						},
+					},
+				},
+			},
+			wantAllowed: false,
+			wantErr:     true,
+			subresource: "ephemeralcontainers",
+			operation:   admission.Update,
+		},
+		{
+			test: "Good container, good init container, bad ephemeral container when updating subresource=='' which sets initContainer and container only",
+			pod: &api.Pod{
+				Spec: api.PodSpec{
+					ServiceAccountName: "default",
+					SecurityContext:    &api.PodSecurityContext{},
+					Containers: []api.Container{
+						{
+							Image:           "good",
+							SecurityContext: &api.SecurityContext{},
+						},
+					},
+					InitContainers: []api.Container{
+						{
+							Image:           "good",
+							SecurityContext: &api.SecurityContext{},
+						},
+					},
+					EphemeralContainers: []api.EphemeralContainer{
+						{
+							EphemeralContainerCommon: api.EphemeralContainerCommon{
+								Image:           "bad",
+								SecurityContext: &api.SecurityContext{},
+							},
+						},
+					},
+				},
+			},
+			wantAllowed: true,
+			wantErr:     false,
+			subresource: "",
+			operation:   admission.Update,
+		},
+
+		{
+			test: "Bad container, good ephemeral container when updating subresource=='ephemeralcontainers' which sets ephemeralcontainers only",
+			pod: &api.Pod{
+				Spec: api.PodSpec{
+					ServiceAccountName: "default",
+					SecurityContext:    &api.PodSecurityContext{},
+					Containers: []api.Container{
+						{
+							Image:           "bad",
+							SecurityContext: &api.SecurityContext{},
+						},
+					},
+					EphemeralContainers: []api.EphemeralContainer{
+						{
+							EphemeralContainerCommon: api.EphemeralContainerCommon{
+								Image:           "good",
+								SecurityContext: &api.SecurityContext{},
+							},
+						},
+					},
+				},
+			},
+			wantAllowed: true,
+			wantErr:     false,
+			subresource: "ephemeralcontainers",
+			operation:   admission.Update,
+		},
+		{
+			test: "Good ephemeral container",
+			pod: &api.Pod{
+				Spec: api.PodSpec{
+					ServiceAccountName: "default",
+					SecurityContext:    &api.PodSecurityContext{},
+					EphemeralContainers: []api.EphemeralContainer{
+						{
+							EphemeralContainerCommon: api.EphemeralContainerCommon{
+								Image:           "good",
+								SecurityContext: &api.SecurityContext{},
+							},
+						},
+					},
+				},
+			},
+			wantAllowed: true,
+			wantErr:     false,
+			subresource: "ephemeralcontainers",
+			operation:   admission.Update,
 		},
 	}
 	for _, tt := range tests {
@@ -753,13 +887,13 @@ func TestContainerCombinations(t *testing.T) {
 			}
 			defer server.Close()
 
-			wh, err := newImagePolicyWebhook(t, server.URL, clientCert, clientKey, caCert, 0, false)
+			wh, err := newImagePolicyWebhook(server.URL, clientCert, clientKey, caCert, 0, false)
 			if err != nil {
 				t.Errorf("%s: failed to create client: %v", tt.test, err)
 				return
 			}
 
-			attr := admission.NewAttributesRecord(tt.pod, nil, api.Kind("Pod").WithVersion("version"), "namespace", "", api.Resource("pods").WithVersion("version"), "", admission.Create, &metav1.CreateOptions{}, false, &user.DefaultInfo{})
+			attr := admission.NewAttributesRecord(tt.pod, nil, api.Kind("Pod").WithVersion("version"), "namespace", "", api.Resource("pods").WithVersion("version"), tt.subresource, tt.operation, &metav1.CreateOptions{}, false, &user.DefaultInfo{})
 
 			err = wh.Validate(context.TODO(), attr, nil)
 			if tt.wantAllowed {
@@ -847,7 +981,7 @@ func TestDefaultAllow(t *testing.T) {
 			}
 			defer server.Close()
 
-			wh, err := newImagePolicyWebhook(t, server.URL, clientCert, clientKey, caCert, 0, tt.defaultAllow)
+			wh, err := newImagePolicyWebhook(server.URL, clientCert, clientKey, caCert, 0, tt.defaultAllow)
 			if err != nil {
 				t.Errorf("%s: failed to create client: %v", tt.test, err)
 				return
@@ -954,7 +1088,7 @@ func TestAnnotationFiltering(t *testing.T) {
 			}
 			defer server.Close()
 
-			wh, err := newImagePolicyWebhook(t, server.URL, clientCert, clientKey, caCert, 0, true)
+			wh, err := newImagePolicyWebhook(server.URL, clientCert, clientKey, caCert, 0, true)
 			if err != nil {
 				t.Errorf("%s: failed to create client: %v", tt.test, err)
 				return
@@ -1047,7 +1181,7 @@ func TestReturnedAnnotationAdd(t *testing.T) {
 			}
 			defer server.Close()
 
-			wh, err := newImagePolicyWebhook(t, server.URL, clientCert, clientKey, caCert, 0, true)
+			wh, err := newImagePolicyWebhook(server.URL, clientCert, clientKey, caCert, 0, true)
 			if err != nil {
 				t.Errorf("%s: failed to create client: %v", tt.test, err)
 				return

plugin/pkg/admission/serviceaccount/admission.go

@@ -99,7 +99,7 @@ var _ = genericadmissioninitializer.WantsExternalKubeInformerFactory(&Plugin{})
 // 5. If MountServiceAccountToken is true, it adds a VolumeMount with the pod's ServiceAccount's api token secret to containers
 func NewServiceAccount() *Plugin {
 	return &Plugin{
-		Handler: admission.NewHandler(admission.Create),
+		Handler: admission.NewHandler(admission.Create, admission.Update),
 		// TODO: enable this once we've swept secret usage to account for adding secret references to service accounts
 		LimitSecretReferences: false,
 		// Auto mount service account API token secrets
@@ -139,7 +139,10 @@ func (s *Plugin) Admit(ctx context.Context, a admission.Attributes, o admission.
 	if shouldIgnore(a) {
 		return nil
 	}
-
+	if a.GetOperation() != admission.Create {
+		// we only mutate pods during create requests
+		return nil
+	}
 	pod := a.GetObject().(*api.Pod)
 
 	// Don't modify the spec of mirror pods.
@@ -156,7 +159,7 @@ func (s *Plugin) Admit(ctx context.Context, a admission.Attributes, o admission.
 
 	serviceAccount, err := s.getServiceAccount(a.GetNamespace(), pod.Spec.ServiceAccountName)
 	if err != nil {
-		return admission.NewForbidden(a, fmt.Errorf("error looking up service account %s/%s: %v", a.GetNamespace(), pod.Spec.ServiceAccountName, err))
+		return admission.NewForbidden(a, fmt.Errorf("error looking up service account %s/%s: %w", a.GetNamespace(), pod.Spec.ServiceAccountName, err))
 	}
 	if s.MountServiceAccountToken && shouldAutomount(serviceAccount, pod) {
 		s.mountServiceAccountToken(serviceAccount, pod)
@@ -179,6 +182,15 @@ func (s *Plugin) Validate(ctx context.Context, a admission.Attributes, o admissi
 
 	pod := a.GetObject().(*api.Pod)
 
+	if a.GetOperation() == admission.Update && a.GetSubresource() == "ephemeralcontainers" {
+		return s.limitEphemeralContainerSecretReferences(pod, a)
+	}
+
+	if a.GetOperation() != admission.Create {
+		// we only validate pod specs during create requests
+		return nil
+	}
+
 	// Mirror pods have restrictions on what they can reference
 	if _, isMirrorPod := pod.Annotations[api.MirrorPodAnnotationKey]; isMirrorPod {
 		if len(pod.Spec.ServiceAccountName) != 0 {
@@ -204,6 +216,10 @@ func (s *Plugin) Validate(ctx context.Context, a admission.Attributes, o admissi
 		return nil
 	}
 
+	// Require container pods to have service accounts
+	if len(pod.Spec.ServiceAccountName) == 0 {
+		return admission.NewForbidden(a, fmt.Errorf("no service account specified for pod %s/%s", a.GetNamespace(), pod.Name))
+	}
 	// Ensure the referenced service account exists
 	serviceAccount, err := s.getServiceAccount(a.GetNamespace(), pod.Spec.ServiceAccountName)
 	if err != nil {
@@ -220,10 +236,7 @@ func (s *Plugin) Validate(ctx context.Context, a admission.Attributes, o admissi
 }
 
 func shouldIgnore(a admission.Attributes) bool {
-	if a.GetResource().GroupResource() != api.Resource("pods") {
+	if a.GetResource().GroupResource() != api.Resource("pods") || (a.GetSubresource() != "" && a.GetSubresource() != "ephemeralcontainers") {
-		return true
-	}
-	if a.GetSubresource() != "" {
 		return true
 	}
 	obj := a.GetObject()
@@ -349,6 +362,36 @@ func (s *Plugin) limitSecretReferences(serviceAccount *corev1.ServiceAccount, po
 	return nil
 }
 
+func (s *Plugin) limitEphemeralContainerSecretReferences(pod *api.Pod, a admission.Attributes) error {
+	// Require ephemeral container pods to have service accounts
+	if len(pod.Spec.ServiceAccountName) == 0 {
+		return admission.NewForbidden(a, fmt.Errorf("no service account specified for pod %s/%s", a.GetNamespace(), pod.Name))
+	}
+	// Ensure the referenced service account exists
+	serviceAccount, err := s.getServiceAccount(a.GetNamespace(), pod.Spec.ServiceAccountName)
+	if err != nil {
+		return admission.NewForbidden(a, fmt.Errorf("error looking up service account %s/%s: %w", a.GetNamespace(), pod.Spec.ServiceAccountName, err))
+	}
+	if !s.enforceMountableSecrets(serviceAccount) {
+		return nil
+	}
+	// Ensure all secrets the ephemeral containers reference are allowed by the service account
+	mountableSecrets := sets.NewString()
+	for _, s := range serviceAccount.Secrets {
+		mountableSecrets.Insert(s.Name)
+	}
+	for _, container := range pod.Spec.EphemeralContainers {
+		for _, env := range container.Env {
+			if env.ValueFrom != nil && env.ValueFrom.SecretKeyRef != nil {
+				if !mountableSecrets.Has(env.ValueFrom.SecretKeyRef.Name) {
+					return fmt.Errorf("ephemeral container %s with envVar %s referencing secret.secretName=\"%s\" is not allowed because service account %s does not reference that secret", container.Name, env.Name, env.ValueFrom.SecretKeyRef.Name, serviceAccount.Name)
+				}
+			}
+		}
+	}
+	return nil
+}
+
 func (s *Plugin) mountServiceAccountToken(serviceAccount *corev1.ServiceAccount, pod *api.Pod) {
 	// Find the volume and volume name for the ServiceAccountTokenSecret if it already exists
 	tokenVolumeName := ""

plugin/pkg/admission/serviceaccount/admission_test.go

@@ -543,6 +543,34 @@ func TestAllowsReferencedSecret(t *testing.T) {
 	if err := admissiontesting.WithReinvocationTesting(t, admit).Admit(context.TODO(), attrs, nil); err != nil {
 		t.Errorf("Unexpected error: %v", err)
 	}
+
+	pod2 = &api.Pod{
+		Spec: api.PodSpec{
+			ServiceAccountName: DefaultServiceAccountName,
+			EphemeralContainers: []api.EphemeralContainer{
+				{
+					EphemeralContainerCommon: api.EphemeralContainerCommon{
+						Name: "container-2",
+						Env: []api.EnvVar{
+							{
+								Name: "env-1",
+								ValueFrom: &api.EnvVarSource{
+									SecretKeyRef: &api.SecretKeySelector{
+										LocalObjectReference: api.LocalObjectReference{Name: "foo"},
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+	// validate enforces restrictions on secret mounts when operation==create and subresource=='' or operation==update and subresource==ephemeralcontainers"
+	attrs = admission.NewAttributesRecord(pod2, nil, api.Kind("Pod").WithVersion("version"), ns, "myname", api.Resource("pods").WithVersion("version"), "ephemeralcontainers", admission.Update, &metav1.UpdateOptions{}, false, nil)
+	if err := admit.Validate(context.TODO(), attrs, nil); err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
 }
 
 func TestRejectsUnreferencedSecretVolumes(t *testing.T) {
@@ -620,6 +648,66 @@ func TestRejectsUnreferencedSecretVolumes(t *testing.T) {
 	if err := admissiontesting.WithReinvocationTesting(t, admit).Admit(context.TODO(), attrs, nil); err == nil || !strings.Contains(err.Error(), "with envVar") {
 		t.Errorf("Unexpected error: %v", err)
 	}
+
+	pod2 = &api.Pod{
+		Spec: api.PodSpec{
+			ServiceAccountName: DefaultServiceAccountName,
+			InitContainers: []api.Container{
+				{
+					Name: "container-1",
+					Env: []api.EnvVar{
+						{
+							Name: "env-1",
+							ValueFrom: &api.EnvVarSource{
+								SecretKeyRef: &api.SecretKeySelector{
+									LocalObjectReference: api.LocalObjectReference{Name: "foo"},
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+	attrs = admission.NewAttributesRecord(pod2, nil, api.Kind("Pod").WithVersion("version"), ns, "myname", api.Resource("pods").WithVersion("version"), "", admission.Update, &metav1.UpdateOptions{}, false, nil)
+	if err := admissiontesting.WithReinvocationTesting(t, admit).Admit(context.TODO(), attrs, nil); err != nil {
+		t.Errorf("admit only enforces restrictions on secret mounts when operation==create. Unexpected error: %v", err)
+	}
+	attrs = admission.NewAttributesRecord(pod2, nil, api.Kind("Pod").WithVersion("version"), ns, "myname", api.Resource("pods").WithVersion("version"), "", admission.Create, &metav1.CreateOptions{}, false, nil)
+	if err := admit.Validate(context.TODO(), attrs, nil); err == nil || !strings.Contains(err.Error(), "with envVar") {
+		t.Errorf("validate only enforces restrictions on secret mounts when operation==create and subresource==''. Unexpected error: %v", err)
+	}
+
+	pod2 = &api.Pod{
+		Spec: api.PodSpec{
+			ServiceAccountName: DefaultServiceAccountName,
+			EphemeralContainers: []api.EphemeralContainer{
+				{
+					EphemeralContainerCommon: api.EphemeralContainerCommon{
+						Name: "container-2",
+						Env: []api.EnvVar{
+							{
+								Name: "env-1",
+								ValueFrom: &api.EnvVarSource{
+									SecretKeyRef: &api.SecretKeySelector{
+										LocalObjectReference: api.LocalObjectReference{Name: "foo"},
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+	attrs = admission.NewAttributesRecord(pod2, nil, api.Kind("Pod").WithVersion("version"), ns, "myname", api.Resource("pods").WithVersion("version"), "", admission.Update, &metav1.UpdateOptions{}, false, nil)
+	if err := admissiontesting.WithReinvocationTesting(t, admit).Admit(context.TODO(), attrs, nil); err != nil {
+		t.Errorf("admit only enforces restrictions on secret mounts when operation==create and subresource==''. Unexpected error: %v", err)
+	}
+	attrs = admission.NewAttributesRecord(pod2, nil, api.Kind("Pod").WithVersion("version"), ns, "myname", api.Resource("pods").WithVersion("version"), "ephemeralcontainers", admission.Update, &metav1.UpdateOptions{}, false, nil)
+	if err := admit.Validate(context.TODO(), attrs, nil); err == nil || !strings.Contains(err.Error(), "with envVar") {
+		t.Errorf("validate enforces restrictions on secret mounts when operation==update and subresource==ephemeralcontainers. Unexpected error: %v", err)
+	}
 }
 
 func TestAllowUnreferencedSecretVolumesForPermissiveSAs(t *testing.T) {