136 lines
4.8 KiB
Go
136 lines
4.8 KiB
Go
/*
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Copyright 2016 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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// Package policybased implements a standard storage for ClusterRoleBinding that prevents privilege escalation.
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package policybased
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import (
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"context"
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rbacv1 "k8s.io/api/rbac/v1"
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"k8s.io/apimachinery/pkg/api/errors"
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metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
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"k8s.io/apimachinery/pkg/runtime"
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"k8s.io/apiserver/pkg/authorization/authorizer"
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"k8s.io/apiserver/pkg/registry/rest"
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kapihelper "k8s.io/kubernetes/pkg/apis/core/helper"
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"k8s.io/kubernetes/pkg/apis/rbac"
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rbacv1helpers "k8s.io/kubernetes/pkg/apis/rbac/v1"
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rbacregistry "k8s.io/kubernetes/pkg/registry/rbac"
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rbacregistryvalidation "k8s.io/kubernetes/pkg/registry/rbac/validation"
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)
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var groupResource = rbac.Resource("clusterrolebindings")
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type Storage struct {
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rest.StandardStorage
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authorizer authorizer.Authorizer
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ruleResolver rbacregistryvalidation.AuthorizationRuleResolver
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}
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func NewStorage(s rest.StandardStorage, authorizer authorizer.Authorizer, ruleResolver rbacregistryvalidation.AuthorizationRuleResolver) *Storage {
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return &Storage{s, authorizer, ruleResolver}
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}
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// Destroy cleans up resources on shutdown.
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func (r *Storage) Destroy() {
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r.StandardStorage.Destroy()
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}
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func (r *Storage) NamespaceScoped() bool {
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return false
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}
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func (r *Storage) StorageVersion() runtime.GroupVersioner {
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svp, ok := r.StandardStorage.(rest.StorageVersionProvider)
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if !ok {
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return nil
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}
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return svp.StorageVersion()
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}
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var _ rest.StorageVersionProvider = &Storage{}
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func (s *Storage) Create(ctx context.Context, obj runtime.Object, createValidation rest.ValidateObjectFunc, options *metav1.CreateOptions) (runtime.Object, error) {
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if rbacregistry.EscalationAllowed(ctx) {
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return s.StandardStorage.Create(ctx, obj, createValidation, options)
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}
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clusterRoleBinding := obj.(*rbac.ClusterRoleBinding)
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if rbacregistry.BindingAuthorized(ctx, clusterRoleBinding.RoleRef, metav1.NamespaceNone, s.authorizer) {
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return s.StandardStorage.Create(ctx, obj, createValidation, options)
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}
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v1RoleRef := rbacv1.RoleRef{}
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err := rbacv1helpers.Convert_rbac_RoleRef_To_v1_RoleRef(&clusterRoleBinding.RoleRef, &v1RoleRef, nil)
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if err != nil {
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return nil, err
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}
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rules, err := s.ruleResolver.GetRoleReferenceRules(v1RoleRef, metav1.NamespaceNone)
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if err != nil {
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return nil, err
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}
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if err := rbacregistryvalidation.ConfirmNoEscalation(ctx, s.ruleResolver, rules); err != nil {
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return nil, errors.NewForbidden(groupResource, clusterRoleBinding.Name, err)
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}
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return s.StandardStorage.Create(ctx, obj, createValidation, options)
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}
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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) {
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if rbacregistry.EscalationAllowed(ctx) {
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return s.StandardStorage.Update(ctx, name, obj, createValidation, updateValidation, forceAllowCreate, options)
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}
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nonEscalatingInfo := rest.WrapUpdatedObjectInfo(obj, func(ctx context.Context, obj runtime.Object, oldObj runtime.Object) (runtime.Object, error) {
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clusterRoleBinding := obj.(*rbac.ClusterRoleBinding)
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// if we're only mutating fields needed for the GC to eventually delete this obj, return
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if rbacregistry.IsOnlyMutatingGCFields(obj, oldObj, kapihelper.Semantic) {
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return obj, nil
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}
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// if we're explicitly authorized to bind this clusterrole, return
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if rbacregistry.BindingAuthorized(ctx, clusterRoleBinding.RoleRef, metav1.NamespaceNone, s.authorizer) {
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return obj, nil
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}
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// Otherwise, see if we already have all the permissions contained in the referenced clusterrole
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v1RoleRef := rbacv1.RoleRef{}
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err := rbacv1helpers.Convert_rbac_RoleRef_To_v1_RoleRef(&clusterRoleBinding.RoleRef, &v1RoleRef, nil)
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if err != nil {
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return nil, err
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}
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rules, err := s.ruleResolver.GetRoleReferenceRules(v1RoleRef, metav1.NamespaceNone)
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if err != nil {
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return nil, err
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}
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if err := rbacregistryvalidation.ConfirmNoEscalation(ctx, s.ruleResolver, rules); err != nil {
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return nil, errors.NewForbidden(groupResource, clusterRoleBinding.Name, err)
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}
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return obj, nil
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})
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return s.StandardStorage.Update(ctx, name, nonEscalatingInfo, createValidation, updateValidation, forceAllowCreate, options)
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}
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var _ rest.SingularNameProvider = &Storage{}
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func (s *Storage) GetSingularName() string {
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return "clusterrolebinding"
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}
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