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certificate.go
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certificate.go
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// Copyright 2021 Antrea 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 flowaggregator
import (
"bytes"
"context"
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"fmt"
"math/big"
"net"
"time"
v1 "k8s.io/api/core/v1"
"k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/client-go/kubernetes"
"k8s.io/klog/v2"
)
const (
CAConfigMapName = "flow-aggregator-ca"
CAConfigMapKey = "ca.crt"
CAConfigMapNamespace = "flow-aggregator"
ClientSecretNamespace = "flow-aggregator"
// #nosec G101: false positive triggered by variable name which includes "Secret"
ClientSecretName = "flow-aggregator-client-tls"
)
var (
validFrom = time.Now().Add(-time.Hour) // valid an hour earlier to avoid flakes due to clock skew
maxAge = time.Hour * 24 * 365 // one year self-signed certs
)
func generateCACertKey() (*x509.Certificate, *rsa.PrivateKey, []byte, error) {
cert := &x509.Certificate{
SerialNumber: big.NewInt(1),
Subject: pkix.Name{
CommonName: fmt.Sprintf("flow-aggregator-ca@%d", time.Now().Unix()),
},
NotBefore: validFrom,
NotAfter: validFrom.Add(maxAge),
IsCA: true,
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth, x509.ExtKeyUsageServerAuth},
KeyUsage: x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign,
BasicConstraintsValid: true,
}
// generate private key for CA
caKey, err := rsa.GenerateKey(rand.Reader, 2048)
if err != nil {
return nil, nil, nil, err
}
// generate CA certificate
caCert, err := x509.CreateCertificate(rand.Reader, cert, cert, &caKey.PublicKey, caKey)
if err != nil {
return nil, nil, nil, err
}
caPEM := new(bytes.Buffer)
pem.Encode(caPEM, &pem.Block{
Type: "CERTIFICATE",
Bytes: caCert,
})
return cert, caKey, caPEM.Bytes(), err
}
func generateCertKey(caCert *x509.Certificate, caKey *rsa.PrivateKey, isServer bool, flowAggregatorAddress string) ([]byte, []byte, error) {
var cert *x509.Certificate
if isServer {
cert = &x509.Certificate{
SerialNumber: big.NewInt(2),
Subject: pkix.Name{
CommonName: fmt.Sprintf("flow-aggregator-server-certificate@%d", time.Now().Unix()),
},
NotBefore: validFrom,
NotAfter: validFrom.Add(maxAge),
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
KeyUsage: x509.KeyUsageDigitalSignature,
}
if ip := net.ParseIP(flowAggregatorAddress); ip != nil {
cert.IPAddresses = []net.IP{ip}
} else {
cert.DNSNames = []string{flowAggregatorAddress}
// add IP in certicate since flow exporter on Windows Node can't resolve DNS name
flowAggregatorIPs, err := net.LookupIP(flowAggregatorAddress)
if err != nil {
return nil, nil, err
}
cert.IPAddresses = flowAggregatorIPs
}
} else {
cert = &x509.Certificate{
SerialNumber: big.NewInt(3),
Subject: pkix.Name{
CommonName: fmt.Sprintf("flow-aggregator-client-certificate@%d", time.Now().Unix()),
},
NotBefore: validFrom,
NotAfter: validFrom.Add(maxAge),
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth},
KeyUsage: x509.KeyUsageDigitalSignature,
}
}
// generate private key for certificate
certKey, err := rsa.GenerateKey(rand.Reader, 2048)
if err != nil {
return nil, nil, err
}
// sign the certificate using CA certificate and key
certBytes, err := x509.CreateCertificate(rand.Reader, cert, caCert, &certKey.PublicKey, caKey)
if err != nil {
return nil, nil, err
}
certPEM := new(bytes.Buffer)
pem.Encode(certPEM, &pem.Block{
Type: "CERTIFICATE",
Bytes: certBytes,
})
certKeyPEM := new(bytes.Buffer)
pem.Encode(certKeyPEM, &pem.Block{
Type: "RSA PRIVATE KEY",
Bytes: x509.MarshalPKCS1PrivateKey(certKey),
})
return certPEM.Bytes(), certKeyPEM.Bytes(), nil
}
func syncCAAndClientCert(caCert, clientCert, clientKey []byte, k8sClient kubernetes.Interface) error {
klog.Info("Syncing CA certificate, client certificate and client key with ConfigMap")
caConfigMap, err := k8sClient.CoreV1().ConfigMaps(CAConfigMapNamespace).Get(context.TODO(), CAConfigMapName, metav1.GetOptions{})
exists := true
if err != nil {
if !errors.IsNotFound(err) {
return fmt.Errorf("error getting ConfigMap %s: %v", CAConfigMapName, err)
}
exists = false
caConfigMap = &v1.ConfigMap{
ObjectMeta: metav1.ObjectMeta{
Name: CAConfigMapName,
Namespace: CAConfigMapNamespace,
Labels: map[string]string{
"app": "flow-aggregator",
},
},
}
}
caConfigMap.Data = map[string]string{
CAConfigMapKey: string(caCert),
}
if exists {
if _, err := k8sClient.CoreV1().ConfigMaps(CAConfigMapNamespace).Update(context.TODO(), caConfigMap, metav1.UpdateOptions{}); err != nil {
return fmt.Errorf("error updating ConfigMap %s: %v", CAConfigMapName, err)
}
} else {
if _, err := k8sClient.CoreV1().ConfigMaps(CAConfigMapNamespace).Create(context.TODO(), caConfigMap, metav1.CreateOptions{}); err != nil {
return fmt.Errorf("error creating ConfigMap %s: %v", CAConfigMapName, err)
}
}
secret, err := k8sClient.CoreV1().Secrets(ClientSecretNamespace).Get(context.TODO(), ClientSecretName, metav1.GetOptions{})
exists = true
if err != nil {
exists = false
secret = &v1.Secret{
Data: map[string][]byte{
"tls.crt": clientCert,
"tls.key": clientKey,
},
ObjectMeta: metav1.ObjectMeta{
Name: ClientSecretName,
Namespace: ClientSecretNamespace,
},
Type: v1.SecretTypeTLS,
}
}
secret.Data = map[string][]byte{
"tls.crt": clientCert,
"tls.key": clientKey,
}
if exists {
if _, err := k8sClient.CoreV1().Secrets(ClientSecretNamespace).Update(context.TODO(), secret, metav1.UpdateOptions{}); err != nil {
return fmt.Errorf("failed to update Secret %s: %v", ClientSecretName, err)
}
} else {
if _, err := k8sClient.CoreV1().Secrets(ClientSecretNamespace).Create(context.TODO(), secret, metav1.CreateOptions{}); err != nil {
return fmt.Errorf("failed to create Secret %s: %v", ClientSecretName, err)
}
}
return nil
}