admission.go

/*
Copyright 2014 The Kubernetes Authors All rights reserved.

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 scdeny

import (
	"fmt"
	"io"

	"k8s.io/kubernetes/pkg/admission"
	"k8s.io/kubernetes/pkg/api"
	apierrors "k8s.io/kubernetes/pkg/api/errors"
	client "k8s.io/kubernetes/pkg/client/unversioned"
)

func init() {
	admission.RegisterPlugin("SecurityContextDeny", func(client client.Interface, config io.Reader) (admission.Interface, error) {
		return NewSecurityContextDeny(client), nil
	})
}

// plugin contains the client used by the SecurityContextDeny admission controller
type plugin struct {
	*admission.Handler
	client client.Interface
}

// NewSecurityContextDeny creates a new instance of the SecurityContextDeny admission controller
func NewSecurityContextDeny(client client.Interface) admission.Interface {
	return &plugin{
		Handler: admission.NewHandler(admission.Create, admission.Update),
		client:  client,
	}
}

// Admit will deny any SecurityContext that defines options that were not previously available in the api.Container
// struct (Capabilities and Privileged)
func (p *plugin) Admit(a admission.Attributes) (err error) {
	if a.GetResource() != string(api.ResourcePods) {
		return nil
	}

	pod, ok := a.GetObject().(*api.Pod)
	if !ok {
		return apierrors.NewBadRequest("Resource was marked with kind Pod but was unable to be converted")
	}
	for _, v := range pod.Spec.Containers {
		if v.SecurityContext != nil {
			if v.SecurityContext.SELinuxOptions != nil {
				return apierrors.NewForbidden(a.GetResource(), pod.Name, fmt.Errorf("SecurityContext.SELinuxOptions is forbidden"))
			}
			if v.SecurityContext.RunAsUser != nil {
				return apierrors.NewForbidden(a.GetResource(), pod.Name, fmt.Errorf("SecurityContext.RunAsUser is forbidden"))
			}
		}
	}
	return nil
}