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// Copyright 2020 The gVisor 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 injector handles mutating webhook operations.
package injector
import (
"crypto/tls"
"encoding/json"
"fmt"
"net/http"
"os"
"github.com/mattbaird/jsonpatch"
"gvisor.dev/gvisor/pkg/log"
admv1beta1 "k8s.io/api/admission/v1beta1"
admregv1beta1 "k8s.io/api/admissionregistration/v1beta1"
v1 "k8s.io/api/core/v1"
apierrors "k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
kubeclientset "k8s.io/client-go/kubernetes"
)
const (
// Name is the name of the admission webhook service. The admission
// webhook must be exposed in the following service; this is mainly for
// the server certificate.
Name = "gvisor-injection-admission-webhook"
// serviceNamespace is the namespace of the admission webhook service.
serviceNamespace = "e2e"
fullName = Name + "." + serviceNamespace + ".svc"
)
// CreateConfiguration creates MutatingWebhookConfiguration and registers the
// webhook admission controller with the kube-apiserver. The webhook will only
// take effect on pods in the namespaces selected by `podNsSelector`. If `podNsSelector`
// is empty, the webhook will take effect on all pods.
func CreateConfiguration(clientset kubeclientset.Interface, selector *metav1.LabelSelector) error {
fail := admregv1beta1.Fail
config := &admregv1beta1.MutatingWebhookConfiguration{
ObjectMeta: metav1.ObjectMeta{
Name: Name,
},
Webhooks: []admregv1beta1.MutatingWebhook{
{
Name: fullName,
ClientConfig: admregv1beta1.WebhookClientConfig{
Service: &admregv1beta1.ServiceReference{
Name: Name,
Namespace: serviceNamespace,
},
CABundle: caCert,
},
Rules: []admregv1beta1.RuleWithOperations{
{
Operations: []admregv1beta1.OperationType{
admregv1beta1.Create,
},
Rule: admregv1beta1.Rule{
APIGroups: []string{"*"},
APIVersions: []string{"*"},
Resources: []string{"pods"},
},
},
},
FailurePolicy: &fail,
NamespaceSelector: selector,
},
},
}
log.Infof("Creating MutatingWebhookConfiguration %q", config.Name)
if _, err := clientset.AdmissionregistrationV1beta1().MutatingWebhookConfigurations().Create(config); err != nil {
if !apierrors.IsAlreadyExists(err) {
return fmt.Errorf("failed to create MutatingWebhookConfiguration %q: %s", config.Name, err)
}
log.Infof("MutatingWebhookConfiguration %q already exists; use the existing one", config.Name)
}
return nil
}
// GetTLSConfig retrieves the CA cert that signed the cert used by the webhook.
func GetTLSConfig() *tls.Config {
serverCert, err := tls.X509KeyPair(serverCert, serverKey)
if err != nil {
log.Warningf("Failed to generate X509 key pair: %v", err)
os.Exit(1)
}
return &tls.Config{
Certificates: []tls.Certificate{serverCert},
}
}
// Admit performs admission checks and mutations on Pods.
func Admit(writer http.ResponseWriter, req *http.Request) {
review := &admv1beta1.AdmissionReview{}
if err := json.NewDecoder(req.Body).Decode(review); err != nil {
log.Infof("Failed with error (%v) to decode Admit request: %+v", err, *req)
writer.WriteHeader(http.StatusBadRequest)
return
}
log.Debugf("admitPod: %+v", review)
var err error
review.Response, err = admitPod(review.Request)
if err != nil {
log.Warningf("admitPod failed: %v", err)
review.Response = &admv1beta1.AdmissionResponse{
Result: &metav1.Status{
Reason: metav1.StatusReasonInvalid,
Message: err.Error(),
},
}
sendResponse(writer, review)
return
}
log.Debugf("Processed admission review: %+v", review)
sendResponse(writer, review)
}
func sendResponse(writer http.ResponseWriter, response interface{}) {
b, err := json.Marshal(response)
if err != nil {
log.Warningf("Failed with error (%v) to marshal response: %+v", err, response)
writer.WriteHeader(http.StatusInternalServerError)
return
}
writer.WriteHeader(http.StatusOK)
writer.Write(b)
}
func admitPod(req *admv1beta1.AdmissionRequest) (*admv1beta1.AdmissionResponse, error) {
// Verify that the request is indeed a Pod.
resource := metav1.GroupVersionResource{Group: "", Version: "v1", Resource: "pods"}
if req.Resource != resource {
return nil, fmt.Errorf("unexpected resource %+v in pod admission", req.Resource)
}
// Decode the request into a Pod.
pod := &v1.Pod{}
if err := json.Unmarshal(req.Object.Raw, pod); err != nil {
return nil, fmt.Errorf("failed to decode pod object %s/%s", req.Namespace, req.Name)
}
// Copy first to change it.
podCopy := pod.DeepCopy()
updatePod(podCopy)
patch, err := createPatch(req.Object.Raw, podCopy)
if err != nil {
return nil, fmt.Errorf("failed to create patch for pod %s/%s (generatedName: %s)", pod.Namespace, pod.Name, pod.GenerateName)
}
log.Debugf("Patched pod %s/%s (generateName: %s): %+v", pod.Namespace, pod.Name, pod.GenerateName, podCopy)
patchType := admv1beta1.PatchTypeJSONPatch
return &admv1beta1.AdmissionResponse{
Allowed: true,
Patch: patch,
PatchType: &patchType,
}, nil
}
func updatePod(pod *v1.Pod) {
gvisor := "gvisor"
pod.Spec.RuntimeClassName = &gvisor
// We don't run SELinux test for gvisor.
// If SELinuxOptions are specified, this is usually for volume test to pass
// on SELinux. This can be safely ignored.
if pod.Spec.SecurityContext != nil && pod.Spec.SecurityContext.SELinuxOptions != nil {
pod.Spec.SecurityContext.SELinuxOptions = nil
}
for i := range pod.Spec.Containers {
c := &pod.Spec.Containers[i]
if c.SecurityContext != nil && c.SecurityContext.SELinuxOptions != nil {
c.SecurityContext.SELinuxOptions = nil
}
}
for i := range pod.Spec.InitContainers {
c := &pod.Spec.InitContainers[i]
if c.SecurityContext != nil && c.SecurityContext.SELinuxOptions != nil {
c.SecurityContext.SELinuxOptions = nil
}
}
}
func createPatch(old []byte, newObj interface{}) ([]byte, error) {
new, err := json.Marshal(newObj)
if err != nil {
return nil, err
}
patch, err := jsonpatch.CreatePatch(old, new)
if err != nil {
return nil, err
}
return json.Marshal(patch)
}
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