update dependencies (#6267)

Signed-off-by: hongming <coder.scala@gmail.com>

vendor/k8s.io/apiserver/pkg/admission/plugin/policy/validating/accessor.go

@@ -0,0 +1,82 @@
+/*
+Copyright 2024 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package validating
+
+import (
+	"k8s.io/api/admissionregistration/v1"
+	"k8s.io/apimachinery/pkg/types"
+	"k8s.io/apiserver/pkg/admission/plugin/policy/generic"
+)
+
+func NewValidatingAdmissionPolicyAccessor(obj *v1.ValidatingAdmissionPolicy) generic.PolicyAccessor {
+	return &validatingAdmissionPolicyAccessor{
+		ValidatingAdmissionPolicy: obj,
+	}
+}
+
+func NewValidatingAdmissionPolicyBindingAccessor(obj *v1.ValidatingAdmissionPolicyBinding) generic.BindingAccessor {
+	return &validatingAdmissionPolicyBindingAccessor{
+		ValidatingAdmissionPolicyBinding: obj,
+	}
+}
+
+type validatingAdmissionPolicyAccessor struct {
+	*v1.ValidatingAdmissionPolicy
+}
+
+func (v *validatingAdmissionPolicyAccessor) GetNamespace() string {
+	return v.Namespace
+}
+
+func (v *validatingAdmissionPolicyAccessor) GetName() string {
+	return v.Name
+}
+
+func (v *validatingAdmissionPolicyAccessor) GetParamKind() *v1.ParamKind {
+	return v.Spec.ParamKind
+}
+
+func (v *validatingAdmissionPolicyAccessor) GetMatchConstraints() *v1.MatchResources {
+	return v.Spec.MatchConstraints
+}
+
+type validatingAdmissionPolicyBindingAccessor struct {
+	*v1.ValidatingAdmissionPolicyBinding
+}
+
+func (v *validatingAdmissionPolicyBindingAccessor) GetNamespace() string {
+	return v.Namespace
+}
+
+func (v *validatingAdmissionPolicyBindingAccessor) GetName() string {
+	return v.Name
+}
+
+func (v *validatingAdmissionPolicyBindingAccessor) GetPolicyName() types.NamespacedName {
+	return types.NamespacedName{
+		Namespace: "",
+		Name:      v.Spec.PolicyName,
+	}
+}
+
+func (v *validatingAdmissionPolicyBindingAccessor) GetMatchResources() *v1.MatchResources {
+	return v.Spec.MatchResources
+}
+
+func (v *validatingAdmissionPolicyBindingAccessor) GetParamRef() *v1.ParamRef {
+	return v.Spec.ParamRef
+}

vendor/k8s.io/apiserver/pkg/admission/plugin/policy/validating/caching_authorizer.go

@@ -0,0 +1,152 @@
+/*
+Copyright 2023 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package validating
+
+import (
+	"context"
+	"encoding/json"
+	"sort"
+	"strings"
+
+	"k8s.io/apimachinery/pkg/fields"
+	"k8s.io/apimachinery/pkg/labels"
+	"k8s.io/apiserver/pkg/authentication/user"
+	"k8s.io/apiserver/pkg/authorization/authorizer"
+)
+
+type authzResult struct {
+	authorized authorizer.Decision
+	reason     string
+	err        error
+}
+
+type cachingAuthorizer struct {
+	authorizer authorizer.Authorizer
+	decisions  map[string]authzResult
+}
+
+func newCachingAuthorizer(in authorizer.Authorizer) authorizer.Authorizer {
+	return &cachingAuthorizer{
+		authorizer: in,
+		decisions:  make(map[string]authzResult),
+	}
+}
+
+// The attribute accessors known to cache key construction. If this fails to compile, the cache
+// implementation may need to be updated.
+var _ authorizer.Attributes = (interface {
+	GetUser() user.Info
+	GetVerb() string
+	IsReadOnly() bool
+	GetNamespace() string
+	GetResource() string
+	GetSubresource() string
+	GetName() string
+	GetAPIGroup() string
+	GetAPIVersion() string
+	IsResourceRequest() bool
+	GetPath() string
+	GetFieldSelector() (fields.Requirements, error)
+	GetLabelSelector() (labels.Requirements, error)
+})(nil)
+
+// The user info accessors known to cache key construction. If this fails to compile, the cache
+// implementation may need to be updated.
+var _ user.Info = (interface {
+	GetName() string
+	GetUID() string
+	GetGroups() []string
+	GetExtra() map[string][]string
+})(nil)
+
+// Authorize returns an authorization decision by delegating to another Authorizer. If an equivalent
+// check has already been performed, a cached result is returned. Not safe for concurrent use.
+func (ca *cachingAuthorizer) Authorize(ctx context.Context, a authorizer.Attributes) (authorizer.Decision, string, error) {
+	type SerializableAttributes struct {
+		authorizer.AttributesRecord
+		LabelSelector string
+	}
+
+	serializableAttributes := SerializableAttributes{
+		AttributesRecord: authorizer.AttributesRecord{
+			Verb:            a.GetVerb(),
+			Namespace:       a.GetNamespace(),
+			APIGroup:        a.GetAPIGroup(),
+			APIVersion:      a.GetAPIVersion(),
+			Resource:        a.GetResource(),
+			Subresource:     a.GetSubresource(),
+			Name:            a.GetName(),
+			ResourceRequest: a.IsResourceRequest(),
+			Path:            a.GetPath(),
+		},
+	}
+	// in the error case, we won't honor this field selector, so the cache doesn't need it.
+	if fieldSelector, err := a.GetFieldSelector(); len(fieldSelector) > 0 {
+		serializableAttributes.FieldSelectorRequirements, serializableAttributes.FieldSelectorParsingErr = fieldSelector, err
+	}
+	if labelSelector, _ := a.GetLabelSelector(); len(labelSelector) > 0 {
+		// the labels requirements have private elements so those don't help us serialize to a unique key
+		serializableAttributes.LabelSelector = labelSelector.String()
+	}
+
+	if u := a.GetUser(); u != nil {
+		di := &user.DefaultInfo{
+			Name: u.GetName(),
+			UID:  u.GetUID(),
+		}
+
+		// Differently-ordered groups or extras could cause otherwise-equivalent checks to
+		// have distinct cache keys.
+		if groups := u.GetGroups(); len(groups) > 0 {
+			di.Groups = make([]string, len(groups))
+			copy(di.Groups, groups)
+			sort.Strings(di.Groups)
+		}
+
+		if extra := u.GetExtra(); len(extra) > 0 {
+			di.Extra = make(map[string][]string, len(extra))
+			for k, vs := range extra {
+				vdupe := make([]string, len(vs))
+				copy(vdupe, vs)
+				sort.Strings(vdupe)
+				di.Extra[k] = vdupe
+			}
+		}
+
+		serializableAttributes.User = di
+	}
+
+	var b strings.Builder
+	if err := json.NewEncoder(&b).Encode(serializableAttributes); err != nil {
+		return authorizer.DecisionNoOpinion, "", err
+	}
+	key := b.String()
+
+	if cached, ok := ca.decisions[key]; ok {
+		return cached.authorized, cached.reason, cached.err
+	}
+
+	authorized, reason, err := ca.authorizer.Authorize(ctx, a)
+
+	ca.decisions[key] = authzResult{
+		authorized: authorized,
+		reason:     reason,
+		err:        err,
+	}
+
+	return authorized, reason, err
+}

vendor/k8s.io/apiserver/pkg/admission/plugin/policy/validating/dispatcher.go

@@ -0,0 +1,415 @@
+/*
+Copyright 2022 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package validating
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"strings"
+
+	admissionregistrationv1 "k8s.io/api/admissionregistration/v1"
+	v1 "k8s.io/api/core/v1"
+	k8serrors "k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	utiljson "k8s.io/apimachinery/pkg/util/json"
+	"k8s.io/apiserver/pkg/admission"
+	"k8s.io/apiserver/pkg/admission/plugin/policy/generic"
+	celmetrics "k8s.io/apiserver/pkg/admission/plugin/policy/validating/metrics"
+	celconfig "k8s.io/apiserver/pkg/apis/cel"
+	"k8s.io/apiserver/pkg/authorization/authorizer"
+	"k8s.io/apiserver/pkg/warning"
+	"k8s.io/klog/v2"
+)
+
+type dispatcher struct {
+	matcher generic.PolicyMatcher
+	authz   authorizer.Authorizer
+}
+
+var _ generic.Dispatcher[PolicyHook] = &dispatcher{}
+
+func NewDispatcher(
+	authorizer authorizer.Authorizer,
+	matcher generic.PolicyMatcher,
+) generic.Dispatcher[PolicyHook] {
+	return &dispatcher{
+		matcher: matcher,
+		authz:   authorizer,
+	}
+}
+
+// contains the cel PolicyDecisions along with the ValidatingAdmissionPolicy and ValidatingAdmissionPolicyBinding
+// that determined the decision
+type policyDecisionWithMetadata struct {
+	PolicyDecision
+	Definition *admissionregistrationv1.ValidatingAdmissionPolicy
+	Binding    *admissionregistrationv1.ValidatingAdmissionPolicyBinding
+}
+
+// Dispatch implements generic.Dispatcher.
+func (c *dispatcher) Dispatch(ctx context.Context, a admission.Attributes, o admission.ObjectInterfaces, hooks []PolicyHook) error {
+
+	var deniedDecisions []policyDecisionWithMetadata
+
+	addConfigError := func(err error, definition *admissionregistrationv1.ValidatingAdmissionPolicy, binding *admissionregistrationv1.ValidatingAdmissionPolicyBinding) {
+		// we always default the FailurePolicy if it is unset and validate it in API level
+		var policy admissionregistrationv1.FailurePolicyType
+		if definition.Spec.FailurePolicy == nil {
+			policy = admissionregistrationv1.Fail
+		} else {
+			policy = *definition.Spec.FailurePolicy
+		}
+
+		// apply FailurePolicy specified in ValidatingAdmissionPolicy, the default would be Fail
+		switch policy {
+		case admissionregistrationv1.Ignore:
+			// TODO: add metrics for ignored error here
+			return
+		case admissionregistrationv1.Fail:
+			var message string
+			if binding == nil {
+				message = fmt.Errorf("failed to configure policy: %w", err).Error()
+			} else {
+				message = fmt.Errorf("failed to configure binding: %w", err).Error()
+			}
+			deniedDecisions = append(deniedDecisions, policyDecisionWithMetadata{
+				PolicyDecision: PolicyDecision{
+					Action:  ActionDeny,
+					Message: message,
+				},
+				Definition: definition,
+				Binding:    binding,
+			})
+		default:
+			deniedDecisions = append(deniedDecisions, policyDecisionWithMetadata{
+				PolicyDecision: PolicyDecision{
+					Action:  ActionDeny,
+					Message: fmt.Errorf("unrecognized failure policy: '%v'", policy).Error(),
+				},
+				Definition: definition,
+				Binding:    binding,
+			})
+		}
+	}
+
+	authz := newCachingAuthorizer(c.authz)
+
+	for _, hook := range hooks {
+		// versionedAttributes will be set to non-nil inside of the loop, but
+		// is scoped outside of the param loop so we only convert once. We defer
+		// conversion so that it is only performed when we know a policy matches,
+		// saving the cost of converting non-matching requests.
+		var versionedAttr *admission.VersionedAttributes
+
+		definition := hook.Policy
+		matches, matchResource, matchKind, err := c.matcher.DefinitionMatches(a, o, NewValidatingAdmissionPolicyAccessor(definition))
+		if err != nil {
+			// Configuration error.
+			addConfigError(err, definition, nil)
+			continue
+		}
+		if !matches {
+			// Policy definition does not match request
+			continue
+		} else if hook.ConfigurationError != nil {
+			// Configuration error.
+			addConfigError(hook.ConfigurationError, definition, nil)
+			continue
+		}
+
+		auditAnnotationCollector := newAuditAnnotationCollector()
+		for _, binding := range hook.Bindings {
+			// If the key is inside dependentBindings, there is guaranteed to
+			// be a bindingInfo for it
+			matches, err := c.matcher.BindingMatches(a, o, NewValidatingAdmissionPolicyBindingAccessor(binding))
+			if err != nil {
+				// Configuration error.
+				addConfigError(err, definition, binding)
+				continue
+			}
+			if !matches {
+				continue
+			}
+
+			params, err := generic.CollectParams(
+				hook.Policy.Spec.ParamKind,
+				hook.ParamInformer,
+				hook.ParamScope,
+				binding.Spec.ParamRef,
+				a.GetNamespace(),
+			)
+
+			if err != nil {
+				addConfigError(err, definition, binding)
+				continue
+			} else if versionedAttr == nil && len(params) > 0 {
+				// As optimization versionedAttr creation is deferred until
+				// first use. Since > 0 params, we will validate
+				va, err := admission.NewVersionedAttributes(a, matchKind, o)
+				if err != nil {
+					wrappedErr := fmt.Errorf("failed to convert object version: %w", err)
+					addConfigError(wrappedErr, definition, binding)
+					continue
+				}
+				versionedAttr = va
+			}
+
+			var validationResults []ValidateResult
+			var namespace *v1.Namespace
+			namespaceName := a.GetNamespace()
+
+			// Special case, the namespace object has the namespace of itself (maybe a bug).
+			// unset it if the incoming object is a namespace
+			if gvk := a.GetKind(); gvk.Kind == "Namespace" && gvk.Version == "v1" && gvk.Group == "" {
+				namespaceName = ""
+			}
+
+			// if it is cluster scoped, namespaceName will be empty
+			// Otherwise, get the Namespace resource.
+			if namespaceName != "" {
+				namespace, err = c.matcher.GetNamespace(namespaceName)
+				if err != nil {
+					return err
+				}
+			}
+
+			for _, param := range params {
+				var p runtime.Object = param
+				if p != nil && p.GetObjectKind().GroupVersionKind().Empty() {
+					// Make sure param has TypeMeta populated
+					// This is a simple hack to make sure typeMeta is
+					// available to CEL without making copies of objects, etc.
+					p = &wrappedParam{
+						TypeMeta: metav1.TypeMeta{
+							APIVersion: definition.Spec.ParamKind.APIVersion,
+							Kind:       definition.Spec.ParamKind.Kind,
+						},
+						nested: param,
+					}
+				}
+
+				validationResults = append(validationResults,
+					hook.Evaluator.Validate(
+						ctx,
+						matchResource,
+						versionedAttr,
+						p,
+						namespace,
+						celconfig.RuntimeCELCostBudget,
+						authz,
+					),
+				)
+			}
+
+			for _, validationResult := range validationResults {
+				for i, decision := range validationResult.Decisions {
+					switch decision.Action {
+					case ActionAdmit:
+						if decision.Evaluation == EvalError {
+							celmetrics.Metrics.ObserveAdmission(ctx, decision.Elapsed, definition.Name, binding.Name, ErrorType(&decision))
+						}
+					case ActionDeny:
+						for _, action := range binding.Spec.ValidationActions {
+							switch action {
+							case admissionregistrationv1.Deny:
+								deniedDecisions = append(deniedDecisions, policyDecisionWithMetadata{
+									Definition:     definition,
+									Binding:        binding,
+									PolicyDecision: decision,
+								})
+								celmetrics.Metrics.ObserveRejection(ctx, decision.Elapsed, definition.Name, binding.Name, ErrorType(&decision))
+							case admissionregistrationv1.Audit:
+								publishValidationFailureAnnotation(binding, i, decision, versionedAttr)
+								celmetrics.Metrics.ObserveAudit(ctx, decision.Elapsed, definition.Name, binding.Name, ErrorType(&decision))
+							case admissionregistrationv1.Warn:
+								warning.AddWarning(ctx, "", fmt.Sprintf("Validation failed for ValidatingAdmissionPolicy '%s' with binding '%s': %s", definition.Name, binding.Name, decision.Message))
+								celmetrics.Metrics.ObserveWarn(ctx, decision.Elapsed, definition.Name, binding.Name, ErrorType(&decision))
+							}
+						}
+					default:
+						return fmt.Errorf("unrecognized evaluation decision '%s' for ValidatingAdmissionPolicyBinding '%s' with ValidatingAdmissionPolicy '%s'",
+							decision.Action, binding.Name, definition.Name)
+					}
+				}
+
+				for _, auditAnnotation := range validationResult.AuditAnnotations {
+					switch auditAnnotation.Action {
+					case AuditAnnotationActionPublish:
+						value := auditAnnotation.Value
+						if len(auditAnnotation.Value) > maxAuditAnnotationValueLength {
+							value = value[:maxAuditAnnotationValueLength]
+						}
+						auditAnnotationCollector.add(auditAnnotation.Key, value)
+					case AuditAnnotationActionError:
+						// When failurePolicy=fail, audit annotation errors result in deny
+						d := policyDecisionWithMetadata{
+							Definition: definition,
+							Binding:    binding,
+							PolicyDecision: PolicyDecision{
+								Action:     ActionDeny,
+								Evaluation: EvalError,
+								Message:    auditAnnotation.Error,
+								Elapsed:    auditAnnotation.Elapsed,
+							},
+						}
+						deniedDecisions = append(deniedDecisions, d)
+						celmetrics.Metrics.ObserveRejection(ctx, auditAnnotation.Elapsed, definition.Name, binding.Name, ErrorType(&d.PolicyDecision))
+					case AuditAnnotationActionExclude: // skip it
+					default:
+						return fmt.Errorf("unsupported AuditAnnotation Action: %s", auditAnnotation.Action)
+					}
+				}
+			}
+		}
+		auditAnnotationCollector.publish(definition.Name, a)
+	}
+
+	if len(deniedDecisions) > 0 {
+		// TODO: refactor admission.NewForbidden so the name extraction is reusable but the code/reason is customizable
+		var message string
+		deniedDecision := deniedDecisions[0]
+		if deniedDecision.Binding != nil {
+			message = fmt.Sprintf("ValidatingAdmissionPolicy '%s' with binding '%s' denied request: %s", deniedDecision.Definition.Name, deniedDecision.Binding.Name, deniedDecision.Message)
+		} else {
+			message = fmt.Sprintf("ValidatingAdmissionPolicy '%s' denied request: %s", deniedDecision.Definition.Name, deniedDecision.Message)
+		}
+		err := admission.NewForbidden(a, errors.New(message)).(*k8serrors.StatusError)
+		reason := deniedDecision.Reason
+		if len(reason) == 0 {
+			reason = metav1.StatusReasonInvalid
+		}
+		err.ErrStatus.Reason = reason
+		err.ErrStatus.Code = reasonToCode(reason)
+		err.ErrStatus.Details.Causes = append(err.ErrStatus.Details.Causes, metav1.StatusCause{Message: message})
+		return err
+	}
+	return nil
+}
+
+func publishValidationFailureAnnotation(binding *admissionregistrationv1.ValidatingAdmissionPolicyBinding, expressionIndex int, decision PolicyDecision, attributes admission.Attributes) {
+	key := "validation.policy.admission.k8s.io/validation_failure"
+	// Marshal to a list of failures since, in the future, we may need to support multiple failures
+	valueJSON, err := utiljson.Marshal([]ValidationFailureValue{{
+		ExpressionIndex:   expressionIndex,
+		Message:           decision.Message,
+		ValidationActions: binding.Spec.ValidationActions,
+		Binding:           binding.Name,
+		Policy:            binding.Spec.PolicyName,
+	}})
+	if err != nil {
+		klog.Warningf("Failed to set admission audit annotation %s for ValidatingAdmissionPolicy %s and ValidatingAdmissionPolicyBinding %s: %v", key, binding.Spec.PolicyName, binding.Name, err)
+	}
+	value := string(valueJSON)
+	if err := attributes.AddAnnotation(key, value); err != nil {
+		klog.Warningf("Failed to set admission audit annotation %s to %s for ValidatingAdmissionPolicy %s and ValidatingAdmissionPolicyBinding %s: %v", key, value, binding.Spec.PolicyName, binding.Name, err)
+	}
+}
+
+const maxAuditAnnotationValueLength = 10 * 1024
+
+// validationFailureValue defines the JSON format of a "validation.policy.admission.k8s.io/validation_failure" audit
+// annotation value.
+type ValidationFailureValue struct {
+	Message           string                                     `json:"message"`
+	Policy            string                                     `json:"policy"`
+	Binding           string                                     `json:"binding"`
+	ExpressionIndex   int                                        `json:"expressionIndex"`
+	ValidationActions []admissionregistrationv1.ValidationAction `json:"validationActions"`
+}
+
+type auditAnnotationCollector struct {
+	annotations map[string][]string
+}
+
+func newAuditAnnotationCollector() auditAnnotationCollector {
+	return auditAnnotationCollector{annotations: map[string][]string{}}
+}
+
+func (a auditAnnotationCollector) add(key, value string) {
+	// If multiple bindings produces the exact same key and value for an audit annotation,
+	// ignore the duplicates.
+	for _, v := range a.annotations[key] {
+		if v == value {
+			return
+		}
+	}
+	a.annotations[key] = append(a.annotations[key], value)
+}
+
+func (a auditAnnotationCollector) publish(policyName string, attributes admission.Attributes) {
+	for key, bindingAnnotations := range a.annotations {
+		var value string
+		if len(bindingAnnotations) == 1 {
+			value = bindingAnnotations[0]
+		} else {
+			// Multiple distinct values can exist when binding params are used in the valueExpression of an auditAnnotation.
+			// When this happens, the values are concatenated into a comma-separated list.
+			value = strings.Join(bindingAnnotations, ", ")
+		}
+		if err := attributes.AddAnnotation(policyName+"/"+key, value); err != nil {
+			klog.Warningf("Failed to set admission audit annotation %s to %s for ValidatingAdmissionPolicy %s: %v", key, value, policyName, err)
+		}
+	}
+}
+
+// A workaround to fact that native types do not have TypeMeta populated, which
+// is needed for CEL expressions to be able to access the value.
+type wrappedParam struct {
+	metav1.TypeMeta
+	nested runtime.Object
+}
+
+func (w *wrappedParam) MarshalJSON() ([]byte, error) {
+	return nil, errors.New("MarshalJSON unimplemented for wrappedParam")
+}
+
+func (w *wrappedParam) UnmarshalJSON(data []byte) error {
+	return errors.New("UnmarshalJSON unimplemented for wrappedParam")
+}
+
+func (w *wrappedParam) ToUnstructured() interface{} {
+	res, err := runtime.DefaultUnstructuredConverter.ToUnstructured(w.nested)
+
+	if err != nil {
+		return nil
+	}
+
+	metaRes, err := runtime.DefaultUnstructuredConverter.ToUnstructured(&w.TypeMeta)
+	if err != nil {
+		return nil
+	}
+
+	for k, v := range metaRes {
+		res[k] = v
+	}
+
+	return res
+}
+
+func (w *wrappedParam) DeepCopyObject() runtime.Object {
+	return &wrappedParam{
+		TypeMeta: w.TypeMeta,
+		nested:   w.nested.DeepCopyObject(),
+	}
+}
+
+func (w *wrappedParam) GetObjectKind() schema.ObjectKind {
+	return w
+}

vendor/k8s.io/apiserver/pkg/admission/plugin/policy/validating/errors.go

@@ -0,0 +1,38 @@
+/*
+Copyright 2024 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package validating
+
+import (
+	"strings"
+
+	celmetrics "k8s.io/apiserver/pkg/admission/plugin/policy/validating/metrics"
+)
+
+// ErrorType decodes the error to determine the error type
+// that the metrics understand.
+func ErrorType(decision *PolicyDecision) celmetrics.ValidationErrorType {
+	if decision.Evaluation == EvalAdmit {
+		return celmetrics.ValidationNoError
+	}
+	if strings.HasPrefix(decision.Message, "compilation") {
+		return celmetrics.ValidationCompileError
+	}
+	if strings.HasPrefix(decision.Message, "validation failed due to running out of cost budget") {
+		return celmetrics.ValidatingOutOfBudget
+	}
+	return celmetrics.ValidatingInvalidError
+}

vendor/k8s.io/apiserver/pkg/admission/plugin/policy/validating/initializer.go

@@ -0,0 +1,31 @@
+/*
+Copyright 2022 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package validating
+
+import (
+	"context"
+
+	"k8s.io/apiserver/pkg/admission"
+)
+
+type CELPolicyEvaluator interface {
+	admission.InitializationValidator
+
+	Validate(ctx context.Context, a admission.Attributes, o admission.ObjectInterfaces) error
+	HasSynced() bool
+	Run(stopCh <-chan struct{})
+}

vendor/k8s.io/apiserver/pkg/admission/plugin/policy/validating/interface.go

@@ -0,0 +1,95 @@
+/*
+Copyright 2022 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package validating
+
+import (
+	"context"
+
+	celgo "github.com/google/cel-go/cel"
+
+	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apiserver/pkg/admission"
+	"k8s.io/apiserver/pkg/admission/plugin/cel"
+	"k8s.io/apiserver/pkg/authorization/authorizer"
+)
+
+var _ cel.ExpressionAccessor = &ValidationCondition{}
+
+// ValidationCondition contains the inputs needed to compile, evaluate and validate a cel expression
+type ValidationCondition struct {
+	Expression string
+	Message    string
+	Reason     *metav1.StatusReason
+}
+
+func (v *ValidationCondition) GetExpression() string {
+	return v.Expression
+}
+
+func (v *ValidationCondition) ReturnTypes() []*celgo.Type {
+	return []*celgo.Type{celgo.BoolType}
+}
+
+// AuditAnnotationCondition contains the inputs needed to compile, evaluate and publish a cel audit annotation
+type AuditAnnotationCondition struct {
+	Key             string
+	ValueExpression string
+}
+
+func (v *AuditAnnotationCondition) GetExpression() string {
+	return v.ValueExpression
+}
+
+func (v *AuditAnnotationCondition) ReturnTypes() []*celgo.Type {
+	return []*celgo.Type{celgo.StringType, celgo.NullType}
+}
+
+// Variable is a named expression for composition.
+type Variable struct {
+	Name       string
+	Expression string
+}
+
+func (v *Variable) GetExpression() string {
+	return v.Expression
+}
+
+func (v *Variable) ReturnTypes() []*celgo.Type {
+	return []*celgo.Type{celgo.AnyType, celgo.DynType}
+}
+
+func (v *Variable) GetName() string {
+	return v.Name
+}
+
+// ValidateResult defines the result of a Validator.Validate operation.
+type ValidateResult struct {
+	// Decisions specifies the outcome of the validation as well as the details about the decision.
+	Decisions []PolicyDecision
+	// AuditAnnotations specifies the audit annotations that should be recorded for the validation.
+	AuditAnnotations []PolicyAuditAnnotation
+}
+
+// Validator is contains logic for converting ValidationEvaluation to PolicyDecisions
+type Validator interface {
+	// Validate is used to take cel evaluations and convert into decisions
+	// runtimeCELCostBudget was added for testing purpose only. Callers should always use const RuntimeCELCostBudget from k8s.io/apiserver/pkg/apis/cel/config.go as input.
+	Validate(ctx context.Context, matchedResource schema.GroupVersionResource, versionedAttr *admission.VersionedAttributes, versionedParams runtime.Object, namespace *corev1.Namespace, runtimeCELCostBudget int64, authz authorizer.Authorizer) ValidateResult
+}

vendor/k8s.io/apiserver/pkg/admission/plugin/policy/validating/message.go

@@ -0,0 +1,36 @@
+/*
+Copyright 2023 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package validating
+
+import (
+	celgo "github.com/google/cel-go/cel"
+	"k8s.io/apiserver/pkg/admission/plugin/cel"
+)
+
+var _ cel.ExpressionAccessor = (*MessageExpressionCondition)(nil)
+
+type MessageExpressionCondition struct {
+	MessageExpression string
+}
+
+func (m *MessageExpressionCondition) GetExpression() string {
+	return m.MessageExpression
+}
+
+func (m *MessageExpressionCondition) ReturnTypes() []*celgo.Type {
+	return []*celgo.Type{celgo.StringType}
+}

vendor/k8s.io/apiserver/pkg/admission/plugin/policy/validating/metrics/errors.go

@@ -0,0 +1,38 @@
+/*
+Copyright 2024 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package cel
+
+import (
+	"errors"
+
+	apiservercel "k8s.io/apiserver/pkg/cel"
+)
+
+// ErrorType decodes the error to determine the error type
+// that the metrics understand.
+func ErrorType(err error) ValidationErrorType {
+	if err == nil {
+		return ValidationNoError
+	}
+	if errors.Is(err, apiservercel.ErrCompilation) {
+		return ValidationCompileError
+	}
+	if errors.Is(err, apiservercel.ErrOutOfBudget) {
+		return ValidatingOutOfBudget
+	}
+	return ValidatingInvalidError
+}

vendor/k8s.io/apiserver/pkg/admission/plugin/policy/validating/metrics/metrics.go

@@ -0,0 +1,122 @@
+/*
+Copyright 2022 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package cel
+
+import (
+	"context"
+	"time"
+
+	"k8s.io/component-base/metrics"
+	"k8s.io/component-base/metrics/legacyregistry"
+)
+
+const (
+	metricsNamespace = "apiserver"
+	metricsSubsystem = "validating_admission_policy"
+)
+
+// ValidationErrorType defines different error types that happen to a validation expression
+type ValidationErrorType string
+
+const (
+	// ValidationCompileError indicates that the expression fails to compile.
+	ValidationCompileError ValidationErrorType = "compile_error"
+	// ValidatingInvalidError indicates that the expression fails due to internal
+	// errors that are out of the control of the user.
+	ValidatingInvalidError ValidationErrorType = "invalid_error"
+	// ValidatingOutOfBudget indicates that the expression fails due to running
+	// out of cost budget, or the budget cannot be obtained.
+	ValidatingOutOfBudget ValidationErrorType = "out_of_budget"
+	// ValidationNoError indicates that the expression returns without an error.
+	ValidationNoError ValidationErrorType = "no_error"
+)
+
+var (
+	// Metrics provides access to validation admission metrics.
+	Metrics = newValidationAdmissionMetrics()
+)
+
+// ValidatingAdmissionPolicyMetrics aggregates Prometheus metrics related to validation admission control.
+type ValidatingAdmissionPolicyMetrics struct {
+	policyCheck   *metrics.CounterVec
+	policyLatency *metrics.HistogramVec
+}
+
+func newValidationAdmissionMetrics() *ValidatingAdmissionPolicyMetrics {
+	check := metrics.NewCounterVec(
+		&metrics.CounterOpts{
+			Namespace:      metricsNamespace,
+			Subsystem:      metricsSubsystem,
+			Name:           "check_total",
+			Help:           "Validation admission policy check total, labeled by policy and further identified by binding and enforcement action taken.",
+			StabilityLevel: metrics.BETA,
+		},
+		[]string{"policy", "policy_binding", "error_type", "enforcement_action"},
+	)
+	latency := metrics.NewHistogramVec(&metrics.HistogramOpts{
+		Namespace: metricsNamespace,
+		Subsystem: metricsSubsystem,
+		Name:      "check_duration_seconds",
+		Help:      "Validation admission latency for individual validation expressions in seconds, labeled by policy and further including binding and enforcement action taken.",
+		// the bucket distribution here is based oo the benchmark suite at
+		// github.com/DangerOnTheRanger/cel-benchmark performed on 16-core Intel Xeon
+		// the lowest bucket was based around the 180ns/op figure for BenchmarkAccess,
+		// plus some additional leeway to account for the apiserver doing other things
+		// the largest bucket was chosen based on the fact that benchmarks indicate the
+		// same Xeon running a CEL expression close to the estimated cost limit takes
+		// around 760ms, so that bucket should only ever have the slowest CEL expressions
+		// in it
+		Buckets:        []float64{0.0000005, 0.001, 0.01, 0.1, 1.0},
+		StabilityLevel: metrics.BETA,
+	},
+		[]string{"policy", "policy_binding", "error_type", "enforcement_action"},
+	)
+
+	legacyregistry.MustRegister(check)
+	legacyregistry.MustRegister(latency)
+	return &ValidatingAdmissionPolicyMetrics{policyCheck: check, policyLatency: latency}
+}
+
+// Reset resets all validation admission-related Prometheus metrics.
+func (m *ValidatingAdmissionPolicyMetrics) Reset() {
+	m.policyCheck.Reset()
+	m.policyLatency.Reset()
+}
+
+// ObserveAdmission observes a policy validation, with an optional error to indicate the error that may occur but ignored.
+func (m *ValidatingAdmissionPolicyMetrics) ObserveAdmission(ctx context.Context, elapsed time.Duration, policy, binding string, errorType ValidationErrorType) {
+	m.policyCheck.WithContext(ctx).WithLabelValues(policy, binding, string(errorType), "allow").Inc()
+	m.policyLatency.WithContext(ctx).WithLabelValues(policy, binding, string(errorType), "allow").Observe(elapsed.Seconds())
+}
+
+// ObserveRejection observes a policy validation error that was at least one of the reasons for a deny.
+func (m *ValidatingAdmissionPolicyMetrics) ObserveRejection(ctx context.Context, elapsed time.Duration, policy, binding string, errorType ValidationErrorType) {
+	m.policyCheck.WithContext(ctx).WithLabelValues(policy, binding, string(errorType), "deny").Inc()
+	m.policyLatency.WithContext(ctx).WithLabelValues(policy, binding, string(errorType), "deny").Observe(elapsed.Seconds())
+}
+
+// ObserveAudit observes a policy validation audit annotation was published for a validation failure.
+func (m *ValidatingAdmissionPolicyMetrics) ObserveAudit(ctx context.Context, elapsed time.Duration, policy, binding string, errorType ValidationErrorType) {
+	m.policyCheck.WithContext(ctx).WithLabelValues(policy, binding, string(errorType), "audit").Inc()
+	m.policyLatency.WithContext(ctx).WithLabelValues(policy, binding, string(errorType), "audit").Observe(elapsed.Seconds())
+}
+
+// ObserveWarn observes a policy validation warning was published for a validation failure.
+func (m *ValidatingAdmissionPolicyMetrics) ObserveWarn(ctx context.Context, elapsed time.Duration, policy, binding string, errorType ValidationErrorType) {
+	m.policyCheck.WithContext(ctx).WithLabelValues(policy, binding, string(errorType), "warn").Inc()
+	m.policyLatency.WithContext(ctx).WithLabelValues(policy, binding, string(errorType), "warn").Observe(elapsed.Seconds())
+}

vendor/k8s.io/apiserver/pkg/admission/plugin/policy/validating/plugin.go

@@ -0,0 +1,215 @@
+/*
+Copyright 2024 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package validating
+
+import (
+	"context"
+	"io"
+	"sync"
+
+	v1 "k8s.io/api/admissionregistration/v1"
+	"k8s.io/apimachinery/pkg/api/meta"
+	"k8s.io/apiserver/pkg/admission"
+	"k8s.io/apiserver/pkg/admission/initializer"
+	"k8s.io/apiserver/pkg/admission/plugin/cel"
+	"k8s.io/apiserver/pkg/admission/plugin/policy/generic"
+	"k8s.io/apiserver/pkg/admission/plugin/policy/matching"
+	"k8s.io/apiserver/pkg/admission/plugin/webhook/matchconditions"
+	"k8s.io/apiserver/pkg/authorization/authorizer"
+	"k8s.io/apiserver/pkg/cel/environment"
+	"k8s.io/apiserver/pkg/features"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
+	"k8s.io/client-go/dynamic"
+	"k8s.io/client-go/informers"
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/component-base/featuregate"
+)
+
+const (
+	// PluginName indicates the name of admission plug-in
+	PluginName = "ValidatingAdmissionPolicy"
+)
+
+var (
+	lazyCompositionEnvTemplateWithStrictCostInit sync.Once
+	lazyCompositionEnvTemplateWithStrictCost     *cel.CompositionEnv
+
+	lazyCompositionEnvTemplateWithoutStrictCostInit sync.Once
+	lazyCompositionEnvTemplateWithoutStrictCost     *cel.CompositionEnv
+)
+
+func getCompositionEnvTemplateWithStrictCost() *cel.CompositionEnv {
+	lazyCompositionEnvTemplateWithStrictCostInit.Do(func() {
+		env, err := cel.NewCompositionEnv(cel.VariablesTypeName, environment.MustBaseEnvSet(environment.DefaultCompatibilityVersion(), true))
+		if err != nil {
+			panic(err)
+		}
+		lazyCompositionEnvTemplateWithStrictCost = env
+	})
+	return lazyCompositionEnvTemplateWithStrictCost
+}
+
+func getCompositionEnvTemplateWithoutStrictCost() *cel.CompositionEnv {
+	lazyCompositionEnvTemplateWithoutStrictCostInit.Do(func() {
+		env, err := cel.NewCompositionEnv(cel.VariablesTypeName, environment.MustBaseEnvSet(environment.DefaultCompatibilityVersion(), false))
+		if err != nil {
+			panic(err)
+		}
+		lazyCompositionEnvTemplateWithoutStrictCost = env
+	})
+	return lazyCompositionEnvTemplateWithoutStrictCost
+}
+
+// Register registers a plugin
+func Register(plugins *admission.Plugins) {
+	plugins.Register(PluginName, func(configFile io.Reader) (admission.Interface, error) {
+		return NewPlugin(configFile), nil
+	})
+}
+
+// Plugin is an implementation of admission.Interface.
+type Policy = v1.ValidatingAdmissionPolicy
+type PolicyBinding = v1.ValidatingAdmissionPolicyBinding
+type PolicyEvaluator = Validator
+type PolicyHook = generic.PolicyHook[*Policy, *PolicyBinding, PolicyEvaluator]
+
+type Plugin struct {
+	*generic.Plugin[PolicyHook]
+}
+
+var _ admission.Interface = &Plugin{}
+var _ admission.ValidationInterface = &Plugin{}
+var _ initializer.WantsFeatures = &Plugin{}
+var _ initializer.WantsExcludedAdmissionResources = &Plugin{}
+
+func NewPlugin(_ io.Reader) *Plugin {
+	handler := admission.NewHandler(admission.Connect, admission.Create, admission.Delete, admission.Update)
+
+	return &Plugin{
+		Plugin: generic.NewPlugin(
+			handler,
+			func(f informers.SharedInformerFactory, client kubernetes.Interface, dynamicClient dynamic.Interface, restMapper meta.RESTMapper) generic.Source[PolicyHook] {
+				return generic.NewPolicySource(
+					f.Admissionregistration().V1().ValidatingAdmissionPolicies().Informer(),
+					f.Admissionregistration().V1().ValidatingAdmissionPolicyBindings().Informer(),
+					NewValidatingAdmissionPolicyAccessor,
+					NewValidatingAdmissionPolicyBindingAccessor,
+					compilePolicy,
+					f,
+					dynamicClient,
+					restMapper,
+				)
+			},
+			func(a authorizer.Authorizer, m *matching.Matcher) generic.Dispatcher[PolicyHook] {
+				return NewDispatcher(a, generic.NewPolicyMatcher(m))
+			},
+		),
+	}
+}
+
+// Validate makes an admission decision based on the request attributes.
+func (a *Plugin) Validate(ctx context.Context, attr admission.Attributes, o admission.ObjectInterfaces) error {
+	return a.Plugin.Dispatch(ctx, attr, o)
+}
+
+func (a *Plugin) InspectFeatureGates(featureGates featuregate.FeatureGate) {
+	a.Plugin.SetEnabled(featureGates.Enabled(features.ValidatingAdmissionPolicy))
+}
+
+func compilePolicy(policy *Policy) Validator {
+	hasParam := false
+	if policy.Spec.ParamKind != nil {
+		hasParam = true
+	}
+	strictCost := utilfeature.DefaultFeatureGate.Enabled(features.StrictCostEnforcementForVAP)
+	optionalVars := cel.OptionalVariableDeclarations{HasParams: hasParam, HasAuthorizer: true, StrictCost: strictCost}
+	expressionOptionalVars := cel.OptionalVariableDeclarations{HasParams: hasParam, HasAuthorizer: false, StrictCost: strictCost}
+	failurePolicy := policy.Spec.FailurePolicy
+	var matcher matchconditions.Matcher = nil
+	matchConditions := policy.Spec.MatchConditions
+	var compositionEnvTemplate *cel.CompositionEnv
+	if strictCost {
+		compositionEnvTemplate = getCompositionEnvTemplateWithStrictCost()
+	} else {
+		compositionEnvTemplate = getCompositionEnvTemplateWithoutStrictCost()
+	}
+	filterCompiler := cel.NewCompositedCompilerFromTemplate(compositionEnvTemplate)
+	filterCompiler.CompileAndStoreVariables(convertv1beta1Variables(policy.Spec.Variables), optionalVars, environment.StoredExpressions)
+
+	if len(matchConditions) > 0 {
+		matchExpressionAccessors := make([]cel.ExpressionAccessor, len(matchConditions))
+		for i := range matchConditions {
+			matchExpressionAccessors[i] = (*matchconditions.MatchCondition)(&matchConditions[i])
+		}
+		matcher = matchconditions.NewMatcher(filterCompiler.Compile(matchExpressionAccessors, optionalVars, environment.StoredExpressions), failurePolicy, "policy", "validate", policy.Name)
+	}
+	res := NewValidator(
+		filterCompiler.Compile(convertv1Validations(policy.Spec.Validations), optionalVars, environment.StoredExpressions),
+		matcher,
+		filterCompiler.Compile(convertv1AuditAnnotations(policy.Spec.AuditAnnotations), optionalVars, environment.StoredExpressions),
+		filterCompiler.Compile(convertv1MessageExpressions(policy.Spec.Validations), expressionOptionalVars, environment.StoredExpressions),
+		failurePolicy,
+	)
+
+	return res
+}
+
+func convertv1Validations(inputValidations []v1.Validation) []cel.ExpressionAccessor {
+	celExpressionAccessor := make([]cel.ExpressionAccessor, len(inputValidations))
+	for i, validation := range inputValidations {
+		validation := ValidationCondition{
+			Expression: validation.Expression,
+			Message:    validation.Message,
+			Reason:     validation.Reason,
+		}
+		celExpressionAccessor[i] = &validation
+	}
+	return celExpressionAccessor
+}
+
+func convertv1MessageExpressions(inputValidations []v1.Validation) []cel.ExpressionAccessor {
+	celExpressionAccessor := make([]cel.ExpressionAccessor, len(inputValidations))
+	for i, validation := range inputValidations {
+		if validation.MessageExpression != "" {
+			condition := MessageExpressionCondition{
+				MessageExpression: validation.MessageExpression,
+			}
+			celExpressionAccessor[i] = &condition
+		}
+	}
+	return celExpressionAccessor
+}
+
+func convertv1AuditAnnotations(inputValidations []v1.AuditAnnotation) []cel.ExpressionAccessor {
+	celExpressionAccessor := make([]cel.ExpressionAccessor, len(inputValidations))
+	for i, validation := range inputValidations {
+		validation := AuditAnnotationCondition{
+			Key:             validation.Key,
+			ValueExpression: validation.ValueExpression,
+		}
+		celExpressionAccessor[i] = &validation
+	}
+	return celExpressionAccessor
+}
+
+func convertv1beta1Variables(variables []v1.Variable) []cel.NamedExpressionAccessor {
+	namedExpressions := make([]cel.NamedExpressionAccessor, len(variables))
+	for i, variable := range variables {
+		namedExpressions[i] = &Variable{Name: variable.Name, Expression: variable.Expression}
+	}
+	return namedExpressions
+}

vendor/k8s.io/apiserver/pkg/admission/plugin/policy/validating/policy_decision.go

@@ -0,0 +1,87 @@
+/*
+Copyright 2022 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package validating
+
+import (
+	"net/http"
+	"time"
+
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+type PolicyDecisionAction string
+
+const (
+	ActionAdmit PolicyDecisionAction = "admit"
+	ActionDeny  PolicyDecisionAction = "deny"
+)
+
+type PolicyDecisionEvaluation string
+
+const (
+	EvalAdmit PolicyDecisionEvaluation = "admit"
+	EvalError PolicyDecisionEvaluation = "error"
+	EvalDeny  PolicyDecisionEvaluation = "deny"
+)
+
+// PolicyDecision contains the action determined from a cel evaluation along with metadata such as message, reason and duration
+type PolicyDecision struct {
+	Action     PolicyDecisionAction
+	Evaluation PolicyDecisionEvaluation
+	Message    string
+	Reason     metav1.StatusReason
+	Elapsed    time.Duration
+}
+
+type PolicyAuditAnnotationAction string
+
+const (
+	// AuditAnnotationActionPublish indicates that the audit annotation should be
+	// published with the audit event.
+	AuditAnnotationActionPublish PolicyAuditAnnotationAction = "publish"
+	// AuditAnnotationActionError indicates that the valueExpression resulted
+	// in an error.
+	AuditAnnotationActionError PolicyAuditAnnotationAction = "error"
+	// AuditAnnotationActionExclude indicates that the audit annotation should be excluded
+	// because the valueExpression evaluated to null, or because FailurePolicy is Ignore
+	// and the expression failed with a parse error, type check error, or runtime error.
+	AuditAnnotationActionExclude PolicyAuditAnnotationAction = "exclude"
+)
+
+type PolicyAuditAnnotation struct {
+	Key     string
+	Value   string
+	Elapsed time.Duration
+	Action  PolicyAuditAnnotationAction
+	Error   string
+}
+
+func reasonToCode(r metav1.StatusReason) int32 {
+	switch r {
+	case metav1.StatusReasonForbidden:
+		return http.StatusForbidden
+	case metav1.StatusReasonUnauthorized:
+		return http.StatusUnauthorized
+	case metav1.StatusReasonRequestEntityTooLarge:
+		return http.StatusRequestEntityTooLarge
+	case metav1.StatusReasonInvalid:
+		return http.StatusUnprocessableEntity
+	default:
+		// It should not reach here since we only allow above reason to be set from API level
+		return http.StatusUnprocessableEntity
+	}
+}

vendor/k8s.io/apiserver/pkg/admission/plugin/policy/validating/typechecking.go

@@ -0,0 +1,489 @@
+/*
+Copyright 2023 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package validating
+
+import (
+	"errors"
+	"fmt"
+	"sort"
+	"strings"
+	"time"
+
+	"github.com/google/cel-go/cel"
+
+	"k8s.io/api/admissionregistration/v1"
+	"k8s.io/apimachinery/pkg/api/meta"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
+	"k8s.io/apimachinery/pkg/util/sets"
+	"k8s.io/apimachinery/pkg/util/validation/field"
+	"k8s.io/apimachinery/pkg/util/version"
+	plugincel "k8s.io/apiserver/pkg/admission/plugin/cel"
+	apiservercel "k8s.io/apiserver/pkg/cel"
+	"k8s.io/apiserver/pkg/cel/common"
+	"k8s.io/apiserver/pkg/cel/environment"
+	"k8s.io/apiserver/pkg/cel/library"
+	"k8s.io/apiserver/pkg/cel/openapi"
+	"k8s.io/apiserver/pkg/cel/openapi/resolver"
+	"k8s.io/apiserver/pkg/features"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
+	"k8s.io/klog/v2"
+)
+
+const maxTypesToCheck = 10
+
+type TypeChecker struct {
+	SchemaResolver resolver.SchemaResolver
+	RestMapper     meta.RESTMapper
+}
+
+// TypeCheckingContext holds information about the policy being type-checked.
+// The struct is opaque to the caller.
+type TypeCheckingContext struct {
+	gvks          []schema.GroupVersionKind
+	declTypes     []*apiservercel.DeclType
+	paramGVK      schema.GroupVersionKind
+	paramDeclType *apiservercel.DeclType
+
+	variables []v1.Variable
+}
+
+type typeOverwrite struct {
+	object *apiservercel.DeclType
+	params *apiservercel.DeclType
+}
+
+// TypeCheckingResult holds the issues found during type checking, any returned
+// error, and the gvk that the type checking is performed against.
+type TypeCheckingResult struct {
+	// GVK is the associated GVK
+	GVK schema.GroupVersionKind
+	// Issues contain machine-readable information about the typechecking result.
+	Issues error
+	// Err is the possible error that was encounter during type checking.
+	Err error
+}
+
+// TypeCheckingResults is a collection of TypeCheckingResult
+type TypeCheckingResults []*TypeCheckingResult
+
+func (rs TypeCheckingResults) String() string {
+	var messages []string
+	for _, r := range rs {
+		message := r.String()
+		if message != "" {
+			messages = append(messages, message)
+		}
+	}
+	return strings.Join(messages, "\n")
+}
+
+// String converts the result to human-readable form as a string.
+func (r *TypeCheckingResult) String() string {
+	if r.Issues == nil && r.Err == nil {
+		return ""
+	}
+	if r.Err != nil {
+		return fmt.Sprintf("%v: type checking error: %v\n", r.GVK, r.Err)
+	}
+	return fmt.Sprintf("%v: %s\n", r.GVK, r.Issues)
+}
+
+// Check preforms the type check against the given policy, and format the result
+// as []ExpressionWarning that is ready to be set in policy.Status
+// The result is nil if type checking returns no warning.
+// The policy object is NOT mutated. The caller should update Status accordingly
+func (c *TypeChecker) Check(policy *v1.ValidatingAdmissionPolicy) []v1.ExpressionWarning {
+	ctx := c.CreateContext(policy)
+
+	// warnings to return, note that the capacity is optimistically set to zero
+	var warnings []v1.ExpressionWarning // intentionally not setting capacity
+
+	// check main validation expressions and their message expressions, located in spec.validations[*]
+	fieldRef := field.NewPath("spec", "validations")
+	for i, v := range policy.Spec.Validations {
+		results := c.CheckExpression(ctx, v.Expression)
+		if len(results) != 0 {
+			warnings = append(warnings, v1.ExpressionWarning{
+				FieldRef: fieldRef.Index(i).Child("expression").String(),
+				Warning:  results.String(),
+			})
+		}
+		// Note that MessageExpression is optional
+		if v.MessageExpression == "" {
+			continue
+		}
+		results = c.CheckExpression(ctx, v.MessageExpression)
+		if len(results) != 0 {
+			warnings = append(warnings, v1.ExpressionWarning{
+				FieldRef: fieldRef.Index(i).Child("messageExpression").String(),
+				Warning:  results.String(),
+			})
+		}
+	}
+
+	return warnings
+}
+
+// CreateContext resolves all types and their schemas from a policy definition and creates the context.
+func (c *TypeChecker) CreateContext(policy *v1.ValidatingAdmissionPolicy) *TypeCheckingContext {
+	ctx := new(TypeCheckingContext)
+	allGvks := c.typesToCheck(policy)
+	gvks := make([]schema.GroupVersionKind, 0, len(allGvks))
+	declTypes := make([]*apiservercel.DeclType, 0, len(allGvks))
+	for _, gvk := range allGvks {
+		declType, err := c.declType(gvk)
+		if err != nil {
+			// type checking errors MUST NOT alter the behavior of the policy
+			// even if an error occurs.
+			if !errors.Is(err, resolver.ErrSchemaNotFound) {
+				// Anything except ErrSchemaNotFound is an internal error
+				klog.V(2).ErrorS(err, "internal error: schema resolution failure", "gvk", gvk)
+			}
+			// skip for not found or internal error
+			continue
+		}
+		gvks = append(gvks, gvk)
+		declTypes = append(declTypes, declType)
+	}
+	ctx.gvks = gvks
+	ctx.declTypes = declTypes
+
+	paramsGVK := c.paramsGVK(policy) // maybe empty, correctly handled
+	paramsDeclType, err := c.declType(paramsGVK)
+	if err != nil {
+		if !errors.Is(err, resolver.ErrSchemaNotFound) {
+			klog.V(2).ErrorS(err, "internal error: cannot resolve schema for params", "gvk", paramsGVK)
+		}
+		paramsDeclType = nil
+	}
+	ctx.paramGVK = paramsGVK
+	ctx.paramDeclType = paramsDeclType
+	ctx.variables = policy.Spec.Variables
+	return ctx
+}
+
+func (c *TypeChecker) compiler(ctx *TypeCheckingContext, typeOverwrite typeOverwrite) (*plugincel.CompositedCompiler, error) {
+	envSet, err := buildEnvSet(
+		/* hasParams */ ctx.paramDeclType != nil,
+		/* hasAuthorizer */ true,
+		typeOverwrite)
+	if err != nil {
+		return nil, err
+	}
+	env, err := plugincel.NewCompositionEnv(plugincel.VariablesTypeName, envSet)
+	if err != nil {
+		return nil, err
+	}
+	compiler := &plugincel.CompositedCompiler{
+		Compiler:       &typeCheckingCompiler{typeOverwrite: typeOverwrite, compositionEnv: env},
+		CompositionEnv: env,
+	}
+	return compiler, nil
+}
+
+// CheckExpression type checks a single expression, given the context
+func (c *TypeChecker) CheckExpression(ctx *TypeCheckingContext, expression string) TypeCheckingResults {
+	var results TypeCheckingResults
+	for i, gvk := range ctx.gvks {
+		declType := ctx.declTypes[i]
+		compiler, err := c.compiler(ctx, typeOverwrite{
+			object: declType,
+			params: ctx.paramDeclType,
+		})
+		if err != nil {
+			utilruntime.HandleError(err)
+			continue
+		}
+		options := plugincel.OptionalVariableDeclarations{
+			HasParams:     ctx.paramDeclType != nil,
+			HasAuthorizer: true,
+			StrictCost:    utilfeature.DefaultFeatureGate.Enabled(features.StrictCostEnforcementForVAP),
+		}
+		compiler.CompileAndStoreVariables(convertv1beta1Variables(ctx.variables), options, environment.StoredExpressions)
+		result := compiler.CompileCELExpression(celExpression(expression), options, environment.StoredExpressions)
+		if err := result.Error; err != nil {
+			typeCheckingResult := &TypeCheckingResult{GVK: gvk}
+			if err.Type == apiservercel.ErrorTypeInvalid {
+				typeCheckingResult.Issues = err
+			} else {
+				typeCheckingResult.Err = err
+			}
+			results = append(results, typeCheckingResult)
+		}
+	}
+	return results
+}
+
+type celExpression string
+
+func (c celExpression) GetExpression() string {
+	return string(c)
+}
+
+func (c celExpression) ReturnTypes() []*cel.Type {
+	return []*cel.Type{cel.AnyType}
+}
+func generateUniqueTypeName(kind string) string {
+	return fmt.Sprintf("%s%d", kind, time.Now().Nanosecond())
+}
+
+func (c *TypeChecker) declType(gvk schema.GroupVersionKind) (*apiservercel.DeclType, error) {
+	if gvk.Empty() {
+		return nil, nil
+	}
+	s, err := c.SchemaResolver.ResolveSchema(gvk)
+	if err != nil {
+		return nil, err
+	}
+	return common.SchemaDeclType(&openapi.Schema{Schema: s}, true).MaybeAssignTypeName(generateUniqueTypeName(gvk.Kind)), nil
+}
+
+func (c *TypeChecker) paramsGVK(policy *v1.ValidatingAdmissionPolicy) schema.GroupVersionKind {
+	if policy.Spec.ParamKind == nil {
+		return schema.GroupVersionKind{}
+	}
+	gv, err := schema.ParseGroupVersion(policy.Spec.ParamKind.APIVersion)
+	if err != nil {
+		return schema.GroupVersionKind{}
+	}
+	return gv.WithKind(policy.Spec.ParamKind.Kind)
+}
+
+// typesToCheck extracts a list of GVKs that needs type checking from the policy
+// the result is sorted in the order of Group, Version, and Kind
+func (c *TypeChecker) typesToCheck(p *v1.ValidatingAdmissionPolicy) []schema.GroupVersionKind {
+	gvks := sets.New[schema.GroupVersionKind]()
+	if p.Spec.MatchConstraints == nil || len(p.Spec.MatchConstraints.ResourceRules) == 0 {
+		return nil
+	}
+	restMapperRefreshAttempted := false // at most once per policy, refresh RESTMapper and retry resolution.
+	for _, rule := range p.Spec.MatchConstraints.ResourceRules {
+		groups := extractGroups(&rule.Rule)
+		if len(groups) == 0 {
+			continue
+		}
+		versions := extractVersions(&rule.Rule)
+		if len(versions) == 0 {
+			continue
+		}
+		resources := extractResources(&rule.Rule)
+		if len(resources) == 0 {
+			continue
+		}
+		// sort GVRs so that the loop below provides
+		// consistent results.
+		sort.Strings(groups)
+		sort.Strings(versions)
+		sort.Strings(resources)
+		count := 0
+		for _, group := range groups {
+			for _, version := range versions {
+				for _, resource := range resources {
+					gvr := schema.GroupVersionResource{
+						Group:    group,
+						Version:  version,
+						Resource: resource,
+					}
+					resolved, err := c.RestMapper.KindsFor(gvr)
+					if err != nil {
+						if restMapperRefreshAttempted {
+							// RESTMapper refresh happens at most once per policy
+							continue
+						}
+						c.tryRefreshRESTMapper()
+						restMapperRefreshAttempted = true
+						resolved, err = c.RestMapper.KindsFor(gvr)
+						if err != nil {
+							continue
+						}
+					}
+					for _, r := range resolved {
+						if !r.Empty() {
+							gvks.Insert(r)
+							count++
+							// early return if maximum number of types are already
+							// collected
+							if count == maxTypesToCheck {
+								if gvks.Len() == 0 {
+									return nil
+								}
+								return sortGVKList(gvks.UnsortedList())
+							}
+						}
+					}
+				}
+			}
+		}
+	}
+	if gvks.Len() == 0 {
+		return nil
+	}
+	return sortGVKList(gvks.UnsortedList())
+}
+
+func extractGroups(rule *v1.Rule) []string {
+	groups := make([]string, 0, len(rule.APIGroups))
+	for _, group := range rule.APIGroups {
+		// give up if wildcard
+		if strings.ContainsAny(group, "*") {
+			return nil
+		}
+		groups = append(groups, group)
+	}
+	return groups
+}
+
+func extractVersions(rule *v1.Rule) []string {
+	versions := make([]string, 0, len(rule.APIVersions))
+	for _, version := range rule.APIVersions {
+		if strings.ContainsAny(version, "*") {
+			return nil
+		}
+		versions = append(versions, version)
+	}
+	return versions
+}
+
+func extractResources(rule *v1.Rule) []string {
+	resources := make([]string, 0, len(rule.Resources))
+	for _, resource := range rule.Resources {
+		// skip wildcard and subresources
+		if strings.ContainsAny(resource, "*/") {
+			continue
+		}
+		resources = append(resources, resource)
+	}
+	return resources
+}
+
+// sortGVKList sorts the list by Group, Version, and Kind
+// returns the list itself.
+func sortGVKList(list []schema.GroupVersionKind) []schema.GroupVersionKind {
+	sort.Slice(list, func(i, j int) bool {
+		if g := strings.Compare(list[i].Group, list[j].Group); g != 0 {
+			return g < 0
+		}
+		if v := strings.Compare(list[i].Version, list[j].Version); v != 0 {
+			return v < 0
+		}
+		return strings.Compare(list[i].Kind, list[j].Kind) < 0
+	})
+	return list
+}
+
+// tryRefreshRESTMapper refreshes the RESTMapper if it supports refreshing.
+func (c *TypeChecker) tryRefreshRESTMapper() {
+	if r, ok := c.RestMapper.(meta.ResettableRESTMapper); ok {
+		r.Reset()
+	}
+}
+
+func buildEnvSet(hasParams bool, hasAuthorizer bool, types typeOverwrite) (*environment.EnvSet, error) {
+	baseEnv := environment.MustBaseEnvSet(environment.DefaultCompatibilityVersion(), utilfeature.DefaultFeatureGate.Enabled(features.StrictCostEnforcementForVAP))
+	requestType := plugincel.BuildRequestType()
+	namespaceType := plugincel.BuildNamespaceType()
+
+	var varOpts []cel.EnvOption
+	var declTypes []*apiservercel.DeclType
+
+	// namespace, hand-crafted type
+	declTypes = append(declTypes, namespaceType)
+	varOpts = append(varOpts, createVariableOpts(namespaceType, plugincel.NamespaceVarName)...)
+
+	// request, hand-crafted type
+	declTypes = append(declTypes, requestType)
+	varOpts = append(varOpts, createVariableOpts(requestType, plugincel.RequestVarName)...)
+
+	// object and oldObject, same type, type(s) resolved from constraints
+	declTypes = append(declTypes, types.object)
+	varOpts = append(varOpts, createVariableOpts(types.object, plugincel.ObjectVarName, plugincel.OldObjectVarName)...)
+
+	// params, defined by ParamKind
+	if hasParams && types.params != nil {
+		declTypes = append(declTypes, types.params)
+		varOpts = append(varOpts, createVariableOpts(types.params, plugincel.ParamsVarName)...)
+	}
+
+	// authorizer, implicitly available to all expressions of a policy
+	if hasAuthorizer {
+		// we only need its structure but not the variable itself
+		varOpts = append(varOpts, cel.Variable("authorizer", library.AuthorizerType))
+	}
+
+	return baseEnv.Extend(
+		environment.VersionedOptions{
+			// Feature epoch was actually 1.26, but we artificially set it to 1.0 because these
+			// options should always be present.
+			IntroducedVersion: version.MajorMinor(1, 0),
+			EnvOptions:        varOpts,
+			DeclTypes:         declTypes,
+		},
+	)
+}
+
+// createVariableOpts creates a slice of EnvOption
+// that can be used for creating a CEL env containing variables of declType.
+// declType can be nil, in which case the variables will be of DynType.
+func createVariableOpts(declType *apiservercel.DeclType, variables ...string) []cel.EnvOption {
+	opts := make([]cel.EnvOption, 0, len(variables))
+	t := cel.DynType
+	if declType != nil {
+		t = declType.CelType()
+	}
+	for _, v := range variables {
+		opts = append(opts, cel.Variable(v, t))
+	}
+	return opts
+}
+
+type typeCheckingCompiler struct {
+	compositionEnv *plugincel.CompositionEnv
+	typeOverwrite  typeOverwrite
+}
+
+// CompileCELExpression compiles the given expression.
+// The implementation is the same as that of staging/src/k8s.io/apiserver/pkg/admission/plugin/cel/compile.go
+// except that:
+// - object, oldObject, and params are typed instead of Dyn
+// - compiler does not enforce the output type
+// - the compiler does not initialize the program
+func (c *typeCheckingCompiler) CompileCELExpression(expressionAccessor plugincel.ExpressionAccessor, options plugincel.OptionalVariableDeclarations, mode environment.Type) plugincel.CompilationResult {
+	resultError := func(errorString string, errType apiservercel.ErrorType) plugincel.CompilationResult {
+		return plugincel.CompilationResult{
+			Error: &apiservercel.Error{
+				Type:   errType,
+				Detail: errorString,
+			},
+			ExpressionAccessor: expressionAccessor,
+		}
+	}
+	env, err := c.compositionEnv.Env(mode)
+	if err != nil {
+		return resultError(fmt.Sprintf("fail to build env: %v", err), apiservercel.ErrorTypeInternal)
+	}
+	ast, issues := env.Compile(expressionAccessor.GetExpression())
+	if issues != nil {
+		return resultError(issues.String(), apiservercel.ErrorTypeInvalid)
+	}
+	// type checker does not require the program, however the type must still be set.
+	return plugincel.CompilationResult{
+		OutputType: ast.OutputType(),
+	}
+}
+
+var _ plugincel.Compiler = (*typeCheckingCompiler)(nil)

vendor/k8s.io/apiserver/pkg/admission/plugin/policy/validating/validator.go

@@ -0,0 +1,246 @@
+/*
+Copyright 2022 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package validating
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"strings"
+
+	celtypes "github.com/google/cel-go/common/types"
+
+	v1 "k8s.io/api/admissionregistration/v1"
+	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apiserver/pkg/admission"
+	"k8s.io/apiserver/pkg/admission/plugin/cel"
+	"k8s.io/apiserver/pkg/admission/plugin/webhook/matchconditions"
+	celconfig "k8s.io/apiserver/pkg/apis/cel"
+	"k8s.io/apiserver/pkg/authorization/authorizer"
+	apiservercel "k8s.io/apiserver/pkg/cel"
+	"k8s.io/klog/v2"
+)
+
+// validator implements the Validator interface
+type validator struct {
+	celMatcher            matchconditions.Matcher
+	validationFilter      cel.Filter
+	auditAnnotationFilter cel.Filter
+	messageFilter         cel.Filter
+	failPolicy            *v1.FailurePolicyType
+}
+
+func NewValidator(validationFilter cel.Filter, celMatcher matchconditions.Matcher, auditAnnotationFilter, messageFilter cel.Filter, failPolicy *v1.FailurePolicyType) Validator {
+	return &validator{
+		celMatcher:            celMatcher,
+		validationFilter:      validationFilter,
+		auditAnnotationFilter: auditAnnotationFilter,
+		messageFilter:         messageFilter,
+		failPolicy:            failPolicy,
+	}
+}
+
+func policyDecisionActionForError(f v1.FailurePolicyType) PolicyDecisionAction {
+	if f == v1.Ignore {
+		return ActionAdmit
+	}
+	return ActionDeny
+}
+
+func auditAnnotationEvaluationForError(f v1.FailurePolicyType) PolicyAuditAnnotationAction {
+	if f == v1.Ignore {
+		return AuditAnnotationActionExclude
+	}
+	return AuditAnnotationActionError
+}
+
+// Validate takes a list of Evaluation and a failure policy and converts them into actionable PolicyDecisions
+// runtimeCELCostBudget was added for testing purpose only. Callers should always use const RuntimeCELCostBudget from k8s.io/apiserver/pkg/apis/cel/config.go as input.
+
+func (v *validator) Validate(ctx context.Context, matchedResource schema.GroupVersionResource, versionedAttr *admission.VersionedAttributes, versionedParams runtime.Object, namespace *corev1.Namespace, runtimeCELCostBudget int64, authz authorizer.Authorizer) ValidateResult {
+	var f v1.FailurePolicyType
+	if v.failPolicy == nil {
+		f = v1.Fail
+	} else {
+		f = *v.failPolicy
+	}
+	if v.celMatcher != nil {
+		matchResults := v.celMatcher.Match(ctx, versionedAttr, versionedParams, authz)
+		if matchResults.Error != nil {
+			return ValidateResult{
+				Decisions: []PolicyDecision{
+					{
+						Action:     policyDecisionActionForError(f),
+						Evaluation: EvalError,
+						Message:    matchResults.Error.Error(),
+					},
+				},
+			}
+		}
+
+		// if preconditions are not met, then do not return any validations
+		if !matchResults.Matches {
+			return ValidateResult{}
+		}
+	}
+
+	optionalVars := cel.OptionalVariableBindings{VersionedParams: versionedParams, Authorizer: authz}
+	expressionOptionalVars := cel.OptionalVariableBindings{VersionedParams: versionedParams}
+	admissionRequest := cel.CreateAdmissionRequest(versionedAttr.Attributes, metav1.GroupVersionResource(matchedResource), metav1.GroupVersionKind(versionedAttr.VersionedKind))
+	// Decide which fields are exposed
+	ns := cel.CreateNamespaceObject(namespace)
+	evalResults, remainingBudget, err := v.validationFilter.ForInput(ctx, versionedAttr, admissionRequest, optionalVars, ns, runtimeCELCostBudget)
+	if err != nil {
+		return ValidateResult{
+			Decisions: []PolicyDecision{
+				{
+					Action:     policyDecisionActionForError(f),
+					Evaluation: EvalError,
+					Message:    err.Error(),
+				},
+			},
+		}
+	}
+	decisions := make([]PolicyDecision, len(evalResults))
+	messageResults, _, err := v.messageFilter.ForInput(ctx, versionedAttr, admissionRequest, expressionOptionalVars, ns, remainingBudget)
+	for i, evalResult := range evalResults {
+		var decision = &decisions[i]
+		// TODO: move this to generics
+		validation, ok := evalResult.ExpressionAccessor.(*ValidationCondition)
+		if !ok {
+			klog.Error("Invalid type conversion to ValidationCondition")
+			decision.Action = policyDecisionActionForError(f)
+			decision.Evaluation = EvalError
+			decision.Message = "Invalid type sent to validator, expected ValidationCondition"
+			continue
+		}
+
+		var messageResult *cel.EvaluationResult
+		if len(messageResults) > i {
+			messageResult = &messageResults[i]
+		}
+		if evalResult.Error != nil {
+			decision.Action = policyDecisionActionForError(f)
+			decision.Evaluation = EvalError
+			decision.Message = evalResult.Error.Error()
+		} else if errors.Is(err, apiservercel.ErrInternal) || errors.Is(err, apiservercel.ErrOutOfBudget) {
+			decision.Action = policyDecisionActionForError(f)
+			decision.Evaluation = EvalError
+			decision.Message = fmt.Sprintf("failed messageExpression: %s", err)
+		} else if evalResult.EvalResult != celtypes.True {
+			decision.Action = ActionDeny
+			if validation.Reason == nil {
+				decision.Reason = metav1.StatusReasonInvalid
+			} else {
+				decision.Reason = *validation.Reason
+			}
+			// decide the failure message
+			var message string
+			// attempt to set message with messageExpression result
+			if messageResult != nil && messageResult.Error == nil && messageResult.EvalResult != nil {
+				// also fallback if the eval result is non-string (including null) or
+				// whitespaces.
+				if message, ok = messageResult.EvalResult.Value().(string); ok {
+					message = strings.TrimSpace(message)
+					// deny excessively long message from EvalResult
+					if len(message) > celconfig.MaxEvaluatedMessageExpressionSizeBytes {
+						klog.V(2).InfoS("excessively long message denied", "message", message)
+						message = ""
+					}
+					// deny message that contains newlines
+					if strings.ContainsAny(message, "\n") {
+						klog.V(2).InfoS("multi-line message denied", "message", message)
+						message = ""
+					}
+				}
+			}
+			if messageResult != nil && messageResult.Error != nil {
+				// log any error with messageExpression
+				klog.V(2).ErrorS(messageResult.Error, "error while evaluating messageExpression")
+			}
+			// fallback to set message to the custom message
+			if message == "" && len(validation.Message) > 0 {
+				message = strings.TrimSpace(validation.Message)
+			}
+			// fallback to use the expression to compose a message
+			if message == "" {
+				message = fmt.Sprintf("failed expression: %v", strings.TrimSpace(validation.Expression))
+			}
+			decision.Message = message
+		} else {
+			decision.Action = ActionAdmit
+			decision.Evaluation = EvalAdmit
+		}
+	}
+
+	options := cel.OptionalVariableBindings{VersionedParams: versionedParams}
+	auditAnnotationEvalResults, _, err := v.auditAnnotationFilter.ForInput(ctx, versionedAttr, admissionRequest, options, namespace, runtimeCELCostBudget)
+	if err != nil {
+		return ValidateResult{
+			Decisions: []PolicyDecision{
+				{
+					Action:     policyDecisionActionForError(f),
+					Evaluation: EvalError,
+					Message:    err.Error(),
+				},
+			},
+		}
+	}
+
+	auditAnnotationResults := make([]PolicyAuditAnnotation, len(auditAnnotationEvalResults))
+	for i, evalResult := range auditAnnotationEvalResults {
+		if evalResult.ExpressionAccessor == nil {
+			continue
+		}
+		var auditAnnotationResult = &auditAnnotationResults[i]
+		// TODO: move this to generics
+		validation, ok := evalResult.ExpressionAccessor.(*AuditAnnotationCondition)
+		if !ok {
+			klog.Error("Invalid type conversion to AuditAnnotationCondition")
+			auditAnnotationResult.Action = auditAnnotationEvaluationForError(f)
+			auditAnnotationResult.Error = fmt.Sprintf("Invalid type sent to validator, expected AuditAnnotationCondition but got %T", evalResult.ExpressionAccessor)
+			continue
+		}
+		auditAnnotationResult.Key = validation.Key
+
+		if evalResult.Error != nil {
+			auditAnnotationResult.Action = auditAnnotationEvaluationForError(f)
+			auditAnnotationResult.Error = evalResult.Error.Error()
+		} else {
+			switch evalResult.EvalResult.Type() {
+			case celtypes.StringType:
+				value := strings.TrimSpace(evalResult.EvalResult.Value().(string))
+				if len(value) == 0 {
+					auditAnnotationResult.Action = AuditAnnotationActionExclude
+				} else {
+					auditAnnotationResult.Action = AuditAnnotationActionPublish
+					auditAnnotationResult.Value = value
+				}
+			case celtypes.NullType:
+				auditAnnotationResult.Action = AuditAnnotationActionExclude
+			default:
+				auditAnnotationResult.Action = AuditAnnotationActionError
+				auditAnnotationResult.Error = fmt.Sprintf("valueExpression '%v' resulted in unsupported return type: %v. "+
+					"Return type must be either string or null.", validation.ValueExpression, evalResult.EvalResult.Type())
+			}
+		}
+	}
+	return ValidateResult{Decisions: decisions, AuditAnnotations: auditAnnotationResults}
+}