client-certificate.go

/*
Copyright 2020 The Kubermatic Kubernetes Platform contributors.

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 certificates

import (
	"fmt"

	"github.com/kubermatic/kubermatic/api/pkg/resources"
	"github.com/kubermatic/kubermatic/api/pkg/resources/certificates/triple"
	"github.com/kubermatic/kubermatic/api/pkg/resources/reconciling"

	corev1 "k8s.io/api/core/v1"
	certutil "k8s.io/client-go/util/cert"
)

type caGetter func() (*triple.KeyPair, error)

// GetClientCertificateCreator is a generic function to return a secret generator to create a client certificate signed by the cluster CA
func GetClientCertificateCreator(name, commonName string, organizations []string, dataCertKey, dataKeyKey string, getCA caGetter) reconciling.NamedSecretCreatorGetter {
	return func() (string, reconciling.SecretCreator) {
		return name, func(se *corev1.Secret) (*corev1.Secret, error) {
			// TODO: Remove this after the backup controller has been adapter to the new reconciling behaviour
			if se == nil {
				se = &corev1.Secret{}
			}

			ca, err := getCA()
			if err != nil {
				return nil, fmt.Errorf("failed to get CA: %v", err)
			}

			if se.Data == nil {
				se.Data = map[string][]byte{}
			}

			if b, exists := se.Data[dataCertKey]; exists {
				certs, err := certutil.ParseCertsPEM(b)
				if err != nil {
					return nil, fmt.Errorf("failed to parse certificate (key=%s) from existing secret: %v", dataCertKey, err)
				}

				if resources.IsClientCertificateValidForAllOf(certs[0], commonName, organizations, ca.Cert) {
					return se, nil
				}
			}

			newKP, err := triple.NewClientKeyPair(ca, commonName, organizations)
			if err != nil {
				return nil, fmt.Errorf("failed to create key pair: %v", err)
			}

			se.Data[dataKeyKey] = triple.EncodePrivateKeyPEM(newKP.Key)
			se.Data[dataCertKey] = triple.EncodeCertPEM(newKP.Cert)
			// Include the CA for simplicity
			se.Data[resources.CACertSecretKey] = triple.EncodeCertPEM(ca.Cert)

			return se, nil
		}
	}
}