Merge pull request kubernetes#91737 from liggitt/psp-detect

Detect PSP enablement more accurately

Author: k8s-ci-robot

plugin/pkg/admission/security/podsecuritypolicy/admission.go

@@ -127,7 +127,7 @@ func (p *Plugin) Admit(ctx context.Context, a admission.Attributes, o admission.
 	// compute the context. Mutation is allowed. ValidatedPSPAnnotation is not taken into account.
 	allowedPod, pspName, validationErrs, err := p.computeSecurityContext(ctx, a, pod, true, "")
 	if err != nil {
-		return admission.NewForbidden(a, err)
+		return admission.NewForbidden(a, fmt.Errorf("PodSecurityPolicy: %w", err))
 	}
 	if allowedPod != nil {
 		*pod = *allowedPod
@@ -145,8 +145,8 @@ func (p *Plugin) Admit(ctx context.Context, a admission.Attributes, o admission.
 	}
 
 	// we didn't validate against any provider, reject the pod and give the errors for each attempt
-	klog.V(4).Infof("unable to validate pod %s (generate: %s) in namespace %s against any pod security policy: %v", pod.Name, pod.GenerateName, a.GetNamespace(), validationErrs)
-	return admission.NewForbidden(a, fmt.Errorf("unable to validate against any pod security policy: %v", validationErrs))
+	klog.V(4).Infof("unable to admit pod %s (generate: %s) in namespace %s against any pod security policy: %v", pod.Name, pod.GenerateName, a.GetNamespace(), validationErrs)
+	return admission.NewForbidden(a, fmt.Errorf("PodSecurityPolicy: unable to admit pod: %v", validationErrs))
 }
 
 // Validate verifies attributes against the PodSecurityPolicy
@@ -162,7 +162,7 @@ func (p *Plugin) Validate(ctx context.Context, a admission.Attributes, o admissi
 	// compute the context. Mutation is not allowed. ValidatedPSPAnnotation is used as a hint to gain same speed-up.
 	allowedPod, pspName, validationErrs, err := p.computeSecurityContext(ctx, a, pod, false, pod.ObjectMeta.Annotations[psputil.ValidatedPSPAnnotation])
 	if err != nil {
-		return admission.NewForbidden(a, err)
+		return admission.NewForbidden(a, fmt.Errorf("PodSecurityPolicy: %w", err))
 	}
 	if apiequality.Semantic.DeepEqual(pod, allowedPod) {
 		key := auditKeyPrefix + "/" + "validate-policy"
@@ -174,7 +174,7 @@ func (p *Plugin) Validate(ctx context.Context, a admission.Attributes, o admissi
 
 	// we didn't validate against any provider, reject the pod and give the errors for each attempt
 	klog.V(4).Infof("unable to validate pod %s (generate: %s) in namespace %s against any pod security policy: %v", pod.Name, pod.GenerateName, a.GetNamespace(), validationErrs)
-	return admission.NewForbidden(a, fmt.Errorf("unable to validate against any pod security policy: %v", validationErrs))
+	return admission.NewForbidden(a, fmt.Errorf("PodSecurityPolicy: unable to validate pod: %v", validationErrs))
 }
 
 func shouldIgnore(a admission.Attributes) (bool, error) {

test/e2e/framework/psp.go

@@ -19,6 +19,7 @@ package framework
 import (
 	"context"
 	"fmt"
+	"strings"
 	"sync"
 
 	v1 "k8s.io/api/core/v1"
@@ -29,6 +30,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apiserver/pkg/authentication/serviceaccount"
 	clientset "k8s.io/client-go/kubernetes"
+	imageutils "k8s.io/kubernetes/test/utils/image"
 
 	"github.com/onsi/ginkgo"
 
@@ -92,14 +94,34 @@ func IsPodSecurityPolicyEnabled(kubeClient clientset.Interface) bool {
 		psps, err := kubeClient.PolicyV1beta1().PodSecurityPolicies().List(context.TODO(), metav1.ListOptions{})
 		if err != nil {
 			Logf("Error listing PodSecurityPolicies; assuming PodSecurityPolicy is disabled: %v", err)
-			isPSPEnabled = false
-		} else if psps == nil || len(psps.Items) == 0 {
+			return
+		}
+		if psps == nil || len(psps.Items) == 0 {
 			Logf("No PodSecurityPolicies found; assuming PodSecurityPolicy is disabled.")
-			isPSPEnabled = false
-		} else {
-			Logf("Found PodSecurityPolicies; assuming PodSecurityPolicy is enabled.")
-			isPSPEnabled = true
+			return
+		}
+		Logf("Found PodSecurityPolicies; testing pod creation to see if PodSecurityPolicy is enabled")
+		testPod := &v1.Pod{
+			ObjectMeta: metav1.ObjectMeta{GenerateName: "psp-test-pod-"},
+			Spec:       v1.PodSpec{Containers: []v1.Container{{Name: "test", Image: imageutils.GetPauseImageName()}}},
+		}
+		dryRunPod, err := kubeClient.CoreV1().Pods("kube-system").Create(context.TODO(), testPod, metav1.CreateOptions{DryRun: []string{metav1.DryRunAll}})
+		if err != nil {
+			if strings.Contains(err.Error(), "PodSecurityPolicy") {
+				Logf("PodSecurityPolicy error creating dryrun pod; assuming PodSecurityPolicy is enabled: %v", err)
+				isPSPEnabled = true
+			} else {
+				Logf("Error creating dryrun pod; assuming PodSecurityPolicy is disabled: %v", err)
+			}
+			return
+		}
+		pspAnnotation, pspAnnotationExists := dryRunPod.Annotations["kubernetes.io/psp"]
+		if !pspAnnotationExists {
+			Logf("No PSP annotation exists on dry run pod; assuming PodSecurityPolicy is disabled")
+			return
 		}
+		Logf("PSP annotation exists on dry run pod: %q; assuming PodSecurityPolicy is enabled", pspAnnotation)
+		isPSPEnabled = true
 	})
 	return isPSPEnabled
 }