storage.go

/*
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 Role that prevents privilege escalation.
package policybased

import (
	"k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/runtime"
	genericapirequest "k8s.io/apiserver/pkg/endpoints/request"
	"k8s.io/apiserver/pkg/registry/rest"
	kapihelper "k8s.io/kubernetes/pkg/apis/core/helper"
	"k8s.io/kubernetes/pkg/apis/rbac"
	rbacregistry "k8s.io/kubernetes/pkg/registry/rbac"
	rbacregistryvalidation "k8s.io/kubernetes/pkg/registry/rbac/validation"
)

var groupResource = rbac.Resource("roles")

type Storage struct {
	rest.StandardStorage

	ruleResolver rbacregistryvalidation.AuthorizationRuleResolver
}

func NewStorage(s rest.StandardStorage, ruleResolver rbacregistryvalidation.AuthorizationRuleResolver) *Storage {
	return &Storage{s, ruleResolver}
}

func (s *Storage) Create(ctx genericapirequest.Context, obj runtime.Object, createValidation rest.ValidateObjectFunc, includeUninitialized bool) (runtime.Object, error) {
	if rbacregistry.EscalationAllowed(ctx) {
		return s.StandardStorage.Create(ctx, obj, createValidation, includeUninitialized)
	}

	role := obj.(*rbac.Role)
	rules := role.Rules
	if err := rbacregistryvalidation.ConfirmNoEscalation(ctx, s.ruleResolver, rules); err != nil {
		return nil, errors.NewForbidden(groupResource, role.Name, err)
	}
	return s.StandardStorage.Create(ctx, obj, createValidation, includeUninitialized)
}

func (s *Storage) Update(ctx genericapirequest.Context, name string, obj rest.UpdatedObjectInfo, createValidation rest.ValidateObjectFunc, updateValidation rest.ValidateObjectUpdateFunc) (runtime.Object, bool, error) {
	if rbacregistry.EscalationAllowed(ctx) {
		return s.StandardStorage.Update(ctx, name, obj, createValidation, updateValidation)
	}

	nonEscalatingInfo := rest.WrapUpdatedObjectInfo(obj, func(ctx genericapirequest.Context, obj runtime.Object, oldObj runtime.Object) (runtime.Object, error) {
		role := obj.(*rbac.Role)

		// 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
		}

		rules := role.Rules
		if err := rbacregistryvalidation.ConfirmNoEscalation(ctx, s.ruleResolver, rules); err != nil {
			return nil, errors.NewForbidden(groupResource, role.Name, err)
		}
		return obj, nil
	})

	return s.StandardStorage.Update(ctx, name, nonEscalatingInfo, createValidation, updateValidation)
}