140 lines
4.2 KiB
Go
140 lines
4.2 KiB
Go
/*
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Copyright 2015 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 exec
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import (
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"fmt"
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"io"
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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/apiserver/pkg/admission"
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"k8s.io/kubernetes/pkg/api"
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"k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset"
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"k8s.io/kubernetes/pkg/genericapiserver/registry/rest"
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kubeapiserveradmission "k8s.io/kubernetes/pkg/kubeapiserver/admission"
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)
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func init() {
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admission.RegisterPlugin("DenyEscalatingExec", func(config io.Reader) (admission.Interface, error) {
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return NewDenyEscalatingExec(), nil
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})
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// This is for legacy support of the DenyExecOnPrivileged admission controller. Most
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// of the time DenyEscalatingExec should be preferred.
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admission.RegisterPlugin("DenyExecOnPrivileged", func(config io.Reader) (admission.Interface, error) {
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return NewDenyExecOnPrivileged(), nil
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})
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}
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// denyExec is an implementation of admission.Interface which says no to a pod/exec on
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// a pod using host based configurations.
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type denyExec struct {
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*admission.Handler
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client internalclientset.Interface
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// these flags control which items will be checked to deny exec/attach
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hostIPC bool
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hostPID bool
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privileged bool
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}
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var _ = kubeapiserveradmission.WantsInternalClientSet(&denyExec{})
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// NewDenyEscalatingExec creates a new admission controller that denies an exec operation on a pod
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// using host based configurations.
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func NewDenyEscalatingExec() admission.Interface {
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return &denyExec{
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Handler: admission.NewHandler(admission.Connect),
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hostIPC: true,
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hostPID: true,
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privileged: true,
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}
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}
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// NewDenyExecOnPrivileged creates a new admission controller that is only checking the privileged
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// option. This is for legacy support of the DenyExecOnPrivileged admission controller. Most
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// of the time NewDenyEscalatingExec should be preferred.
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func NewDenyExecOnPrivileged() admission.Interface {
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return &denyExec{
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Handler: admission.NewHandler(admission.Connect),
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hostIPC: false,
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hostPID: false,
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privileged: true,
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}
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}
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func (d *denyExec) Admit(a admission.Attributes) (err error) {
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connectRequest, ok := a.GetObject().(*rest.ConnectRequest)
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if !ok {
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return errors.NewBadRequest("a connect request was received, but could not convert the request object.")
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}
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// Only handle exec or attach requests on pods
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if connectRequest.ResourcePath != "pods/exec" && connectRequest.ResourcePath != "pods/attach" {
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return nil
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}
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pod, err := d.client.Core().Pods(a.GetNamespace()).Get(connectRequest.Name, metav1.GetOptions{})
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if err != nil {
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return admission.NewForbidden(a, err)
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}
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if d.hostPID && pod.Spec.SecurityContext != nil && pod.Spec.SecurityContext.HostPID {
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return admission.NewForbidden(a, fmt.Errorf("cannot exec into or attach to a container using host pid"))
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}
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if d.hostIPC && pod.Spec.SecurityContext != nil && pod.Spec.SecurityContext.HostIPC {
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return admission.NewForbidden(a, fmt.Errorf("cannot exec into or attach to a container using host ipc"))
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}
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if d.privileged && isPrivileged(pod) {
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return admission.NewForbidden(a, fmt.Errorf("cannot exec into or attach to a privileged container"))
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}
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return nil
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}
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// isPrivileged will return true a pod has any privileged containers
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func isPrivileged(pod *api.Pod) bool {
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for _, c := range pod.Spec.InitContainers {
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if c.SecurityContext == nil {
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continue
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}
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if *c.SecurityContext.Privileged {
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return true
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}
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}
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for _, c := range pod.Spec.Containers {
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if c.SecurityContext == nil {
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continue
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}
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if *c.SecurityContext.Privileged {
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return true
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}
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}
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return false
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}
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func (d *denyExec) SetInternalClientSet(client internalclientset.Interface) {
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d.client = client
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}
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func (d *denyExec) Validate() error {
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if d.client == nil {
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return fmt.Errorf("missing client")
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}
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return nil
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}
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