/* Copyright 2016 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 policybased implements a standard storage for ClusterRoleBinding that prevents privilege escalation. package policybased import ( "context" rbacv1 "k8s.io/api/rbac/v1" "k8s.io/apimachinery/pkg/api/errors" metav1 "k8s.io/apimachinery/pkg/apis/meta/v1" "k8s.io/apimachinery/pkg/runtime" "k8s.io/apiserver/pkg/authorization/authorizer" "k8s.io/apiserver/pkg/registry/rest" kapihelper "k8s.io/kubernetes/pkg/apis/core/helper" "k8s.io/kubernetes/pkg/apis/rbac" rbacv1helpers "k8s.io/kubernetes/pkg/apis/rbac/v1" rbacregistry "k8s.io/kubernetes/pkg/registry/rbac" rbacregistryvalidation "k8s.io/kubernetes/pkg/registry/rbac/validation" ) var groupResource = rbac.Resource("clusterrolebindings") type Storage struct { rest.StandardStorage authorizer authorizer.Authorizer ruleResolver rbacregistryvalidation.AuthorizationRuleResolver } func NewStorage(s rest.StandardStorage, authorizer authorizer.Authorizer, ruleResolver rbacregistryvalidation.AuthorizationRuleResolver) *Storage { return &Storage{s, authorizer, ruleResolver} } // Destroy cleans up resources on shutdown. func (r *Storage) Destroy() { r.StandardStorage.Destroy() } func (r *Storage) NamespaceScoped() bool { return false } func (r *Storage) StorageVersion() runtime.GroupVersioner { svp, ok := r.StandardStorage.(rest.StorageVersionProvider) if !ok { return nil } return svp.StorageVersion() } var _ rest.StorageVersionProvider = &Storage{} func (s *Storage) Create(ctx context.Context, obj runtime.Object, createValidation rest.ValidateObjectFunc, options *metav1.CreateOptions) (runtime.Object, error) { if rbacregistry.EscalationAllowed(ctx) { return s.StandardStorage.Create(ctx, obj, createValidation, options) } clusterRoleBinding := obj.(*rbac.ClusterRoleBinding) if rbacregistry.BindingAuthorized(ctx, clusterRoleBinding.RoleRef, metav1.NamespaceNone, s.authorizer) { return s.StandardStorage.Create(ctx, obj, createValidation, options) } v1RoleRef := rbacv1.RoleRef{} err := rbacv1helpers.Convert_rbac_RoleRef_To_v1_RoleRef(&clusterRoleBinding.RoleRef, &v1RoleRef, nil) if err != nil { return nil, err } rules, err := s.ruleResolver.GetRoleReferenceRules(v1RoleRef, metav1.NamespaceNone) if err != nil { return nil, err } if err := rbacregistryvalidation.ConfirmNoEscalation(ctx, s.ruleResolver, rules); err != nil { return nil, errors.NewForbidden(groupResource, clusterRoleBinding.Name, err) } return s.StandardStorage.Create(ctx, obj, createValidation, options) } func (s *Storage) Update(ctx context.Context, name string, obj rest.UpdatedObjectInfo, createValidation rest.ValidateObjectFunc, updateValidation rest.ValidateObjectUpdateFunc, forceAllowCreate bool, options *metav1.UpdateOptions) (runtime.Object, bool, error) { if rbacregistry.EscalationAllowed(ctx) { return s.StandardStorage.Update(ctx, name, obj, createValidation, updateValidation, forceAllowCreate, options) } nonEscalatingInfo := rest.WrapUpdatedObjectInfo(obj, func(ctx context.Context, obj runtime.Object, oldObj runtime.Object) (runtime.Object, error) { clusterRoleBinding := obj.(*rbac.ClusterRoleBinding) // if we're only mutating fields needed for the GC to eventually delete this obj, return if rbacregistry.IsOnlyMutatingGCFields(obj, oldObj, kapihelper.Semantic) { return obj, nil } // if we're explicitly authorized to bind this clusterrole, return if rbacregistry.BindingAuthorized(ctx, clusterRoleBinding.RoleRef, metav1.NamespaceNone, s.authorizer) { return obj, nil } // Otherwise, see if we already have all the permissions contained in the referenced clusterrole v1RoleRef := rbacv1.RoleRef{} err := rbacv1helpers.Convert_rbac_RoleRef_To_v1_RoleRef(&clusterRoleBinding.RoleRef, &v1RoleRef, nil) if err != nil { return nil, err } rules, err := s.ruleResolver.GetRoleReferenceRules(v1RoleRef, metav1.NamespaceNone) if err != nil { return nil, err } if err := rbacregistryvalidation.ConfirmNoEscalation(ctx, s.ruleResolver, rules); err != nil { return nil, errors.NewForbidden(groupResource, clusterRoleBinding.Name, err) } return obj, nil }) return s.StandardStorage.Update(ctx, name, nonEscalatingInfo, createValidation, updateValidation, forceAllowCreate, options) } var _ rest.SingularNameProvider = &Storage{} func (s *Storage) GetSingularName() string { snp, ok := s.StandardStorage.(rest.SingularNameProvider) if !ok { return "" } return snp.GetSingularName() }