1/* 2Copyright 2016 The Kubernetes Authors. 3 4Licensed under the Apache License, Version 2.0 (the "License"); 5you may not use this file except in compliance with the License. 6You may obtain a copy of the License at 7 8 http://www.apache.org/licenses/LICENSE-2.0 9 10Unless required by applicable law or agreed to in writing, software 11distributed under the License is distributed on an "AS IS" BASIS, 12WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13See the License for the specific language governing permissions and 14limitations under the License. 15*/ 16 17// Package policybased implements a standard storage for RoleBinding that prevents privilege escalation. 18package policybased 19 20import ( 21 "context" 22 23 rbacv1 "k8s.io/api/rbac/v1" 24 "k8s.io/apimachinery/pkg/api/errors" 25 metav1 "k8s.io/apimachinery/pkg/apis/meta/v1" 26 "k8s.io/apimachinery/pkg/runtime" 27 "k8s.io/apiserver/pkg/authorization/authorizer" 28 genericapirequest "k8s.io/apiserver/pkg/endpoints/request" 29 "k8s.io/apiserver/pkg/registry/rest" 30 kapihelper "k8s.io/kubernetes/pkg/apis/core/helper" 31 "k8s.io/kubernetes/pkg/apis/rbac" 32 rbacv1helpers "k8s.io/kubernetes/pkg/apis/rbac/v1" 33 rbacregistry "k8s.io/kubernetes/pkg/registry/rbac" 34 rbacregistryvalidation "k8s.io/kubernetes/pkg/registry/rbac/validation" 35) 36 37var groupResource = rbac.Resource("rolebindings") 38 39type Storage struct { 40 rest.StandardStorage 41 42 authorizer authorizer.Authorizer 43 44 ruleResolver rbacregistryvalidation.AuthorizationRuleResolver 45} 46 47func NewStorage(s rest.StandardStorage, authorizer authorizer.Authorizer, ruleResolver rbacregistryvalidation.AuthorizationRuleResolver) *Storage { 48 return &Storage{s, authorizer, ruleResolver} 49} 50 51func (r *Storage) NamespaceScoped() bool { 52 return true 53} 54 55func (r *Storage) StorageVersion() runtime.GroupVersioner { 56 svp, ok := r.StandardStorage.(rest.StorageVersionProvider) 57 if !ok { 58 return nil 59 } 60 return svp.StorageVersion() 61} 62 63var _ rest.StorageVersionProvider = &Storage{} 64 65func (s *Storage) Create(ctx context.Context, obj runtime.Object, createValidation rest.ValidateObjectFunc, options *metav1.CreateOptions) (runtime.Object, error) { 66 if rbacregistry.EscalationAllowed(ctx) { 67 return s.StandardStorage.Create(ctx, obj, createValidation, options) 68 } 69 70 // Get the namespace from the context (populated from the URL). 71 // The namespace in the object can be empty until StandardStorage.Create()->BeforeCreate() populates it from the context. 72 namespace, ok := genericapirequest.NamespaceFrom(ctx) 73 if !ok { 74 return nil, errors.NewBadRequest("namespace is required") 75 } 76 77 roleBinding := obj.(*rbac.RoleBinding) 78 if rbacregistry.BindingAuthorized(ctx, roleBinding.RoleRef, namespace, s.authorizer) { 79 return s.StandardStorage.Create(ctx, obj, createValidation, options) 80 } 81 82 v1RoleRef := rbacv1.RoleRef{} 83 err := rbacv1helpers.Convert_rbac_RoleRef_To_v1_RoleRef(&roleBinding.RoleRef, &v1RoleRef, nil) 84 if err != nil { 85 return nil, err 86 } 87 rules, err := s.ruleResolver.GetRoleReferenceRules(v1RoleRef, namespace) 88 if err != nil { 89 return nil, err 90 } 91 if err := rbacregistryvalidation.ConfirmNoEscalation(ctx, s.ruleResolver, rules); err != nil { 92 return nil, errors.NewForbidden(groupResource, roleBinding.Name, err) 93 } 94 return s.StandardStorage.Create(ctx, obj, createValidation, options) 95} 96 97func (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) { 98 if rbacregistry.EscalationAllowed(ctx) { 99 return s.StandardStorage.Update(ctx, name, obj, createValidation, updateValidation, forceAllowCreate, options) 100 } 101 102 nonEscalatingInfo := rest.WrapUpdatedObjectInfo(obj, func(ctx context.Context, obj runtime.Object, oldObj runtime.Object) (runtime.Object, error) { 103 // Get the namespace from the context (populated from the URL). 104 // The namespace in the object can be empty until StandardStorage.Update()->BeforeUpdate() populates it from the context. 105 namespace, ok := genericapirequest.NamespaceFrom(ctx) 106 if !ok { 107 return nil, errors.NewBadRequest("namespace is required") 108 } 109 110 roleBinding := obj.(*rbac.RoleBinding) 111 112 // if we're only mutating fields needed for the GC to eventually delete this obj, return 113 if rbacregistry.IsOnlyMutatingGCFields(obj, oldObj, kapihelper.Semantic) { 114 return obj, nil 115 } 116 117 // if we're explicitly authorized to bind this role, return 118 if rbacregistry.BindingAuthorized(ctx, roleBinding.RoleRef, namespace, s.authorizer) { 119 return obj, nil 120 } 121 122 // Otherwise, see if we already have all the permissions contained in the referenced role 123 v1RoleRef := rbacv1.RoleRef{} 124 err := rbacv1helpers.Convert_rbac_RoleRef_To_v1_RoleRef(&roleBinding.RoleRef, &v1RoleRef, nil) 125 if err != nil { 126 return nil, err 127 } 128 rules, err := s.ruleResolver.GetRoleReferenceRules(v1RoleRef, namespace) 129 if err != nil { 130 return nil, err 131 } 132 if err := rbacregistryvalidation.ConfirmNoEscalation(ctx, s.ruleResolver, rules); err != nil { 133 return nil, errors.NewForbidden(groupResource, roleBinding.Name, err) 134 } 135 return obj, nil 136 }) 137 138 return s.StandardStorage.Update(ctx, name, nonEscalatingInfo, createValidation, updateValidation, forceAllowCreate, options) 139} 140