metropolis/node/kubernetes/pki/kubernetes.go - monogon - Gitiles

 // Copyright 2020 The Monogon Project Authors.
 //
 // SPDX-License-Identifier: Apache-2.0
 //
 // 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 pki builds upon metropolis/pkg/pki/ to provide an
 // etcd-backed implementation of all x509 PKI Certificates/CAs required to run
 // Kubernetes.
 // Most elements of the PKI are 'static' long-standing certificates/credentials
 // stored within etcd. However, this package also provides a method to generate
 // 'volatile' (in-memory) certificates/credentials for per-node Kubelets and
 // any client certificates.
 package pki

 import (
 	"context"
 	"crypto/rand"
 	"crypto/rsa"
 	"crypto/x509"
 	"encoding/pem"
 	"fmt"
 	"net"

 	"go.etcd.io/etcd/clientv3"
 	"k8s.io/client-go/tools/clientcmd"
 	configapi "k8s.io/client-go/tools/clientcmd/api"

 	common "source.monogon.dev/metropolis/node"
 	"source.monogon.dev/metropolis/pkg/logtree"
 	opki "source.monogon.dev/metropolis/pkg/pki"
 )

 // KubeCertificateName is an enum-like unique name of a static Kubernetes
 // certificate. The value of the name is used as the unique part of an etcd
 // path where the certificate and key are stored.
 type KubeCertificateName string

 const (
 	// The main Kubernetes CA, used to authenticate API consumers, and servers.
 	IdCA KubeCertificateName = "id-ca"

 	// Kubernetes apiserver server certificate.
 	APIServer KubeCertificateName = "apiserver"

 	// APIServer client certificate used to authenticate to kubelets.
 	APIServerKubeletClient KubeCertificateName = "apiserver-kubelet-client"

 	// Kubernetes Controller manager client certificate, used to authenticate
 	// to the apiserver.
 	ControllerManagerClient KubeCertificateName = "controller-manager-client"
 	// Kubernetes Controller manager server certificate, used to run its HTTP
 	// server.
 	ControllerManager KubeCertificateName = "controller-manager"

 	// Kubernetes Scheduler client certificate, used to authenticate to the apiserver.
 	SchedulerClient KubeCertificateName = "scheduler-client"
 	// Kubernetes scheduler server certificate, used to run its HTTP server.
 	Scheduler KubeCertificateName = "scheduler"

 	// Root-on-kube (system:masters) client certificate. Used to control the
 	// apiserver (and resources) by Metropolis internally.
 	Master KubeCertificateName = "master"

 	// OpenAPI Kubernetes Aggregation CA.
 	//   https://kubernetes.io/docs/tasks/extend-kubernetes/configure-aggregation-layer/#ca-reusage-and-conflicts
 	AggregationCA    KubeCertificateName = "aggregation-ca"
 	FrontProxyClient KubeCertificateName = "front-proxy-client"
 )

 const (
 	// etcdPrefix is where all the PKI data is stored in etcd.
 	etcdPrefix = "/kube-pki/"
 	// serviceAccountKeyName is the etcd path part that is used to store the
 	// ServiceAccount authentication secret. This is not a certificate, just an
 	// RSA key.
 	serviceAccountKeyName = "service-account-privkey"
 )

 // PKI manages all PKI resources required to run Kubernetes on Metropolis. It
 // contains all static certificates, which can be retrieved, or be used to
 // generate Kubeconfigs from.
 type PKI struct {
 	namespace    opki.Namespace
 	logger       logtree.LeveledLogger
 	KV           clientv3.KV
 	Certificates map[KubeCertificateName]*opki.Certificate
 }

 func New(l logtree.LeveledLogger, kv clientv3.KV) *PKI {
 	pki := PKI{
 		namespace:    opki.Namespaced(etcdPrefix),
 		logger:       l,
 		KV:           kv,
 		Certificates: make(map[KubeCertificateName]*opki.Certificate),
 	}

 	make := func(i, name KubeCertificateName, template x509.Certificate) {
 		pki.Certificates[name] = pki.namespace.New(pki.Certificates[i], string(name), template)
 	}

 	pki.Certificates[IdCA] = pki.namespace.New(opki.SelfSigned, string(IdCA), opki.CA("Metropolis Kubernetes ID CA"))
 	make(IdCA, APIServer, opki.Server(
 		[]string{
 			"kubernetes",
 			"kubernetes.default",
 			"kubernetes.default.svc",
 			"kubernetes.default.svc.cluster",
 			"kubernetes.default.svc.cluster.local",
 			"localhost",
 		},
 		// TODO(q3k): add service network internal apiserver address
 		[]net.IP{{10, 0, 255, 1}, {127, 0, 0, 1}},
 	))
 	make(IdCA, APIServerKubeletClient, opki.Client("metropolis:apiserver-kubelet-client", nil))
 	make(IdCA, ControllerManagerClient, opki.Client("system:kube-controller-manager", nil))
 	make(IdCA, ControllerManager, opki.Server([]string{"kube-controller-manager.local"}, nil))
 	make(IdCA, SchedulerClient, opki.Client("system:kube-scheduler", nil))
 	make(IdCA, Scheduler, opki.Server([]string{"kube-scheduler.local"}, nil))
 	make(IdCA, Master, opki.Client("metropolis:master", []string{"system:masters"}))

 	pki.Certificates[AggregationCA] = pki.namespace.New(opki.SelfSigned, string(AggregationCA), opki.CA("Metropolis OpenAPI Aggregation CA"))
 	make(AggregationCA, FrontProxyClient, opki.Client("front-proxy-client", nil))

 	return &pki
 }

 // EnsureAll ensures that all static certificates (and the serviceaccount key)
 // are present on etcd.
 func (k *PKI) EnsureAll(ctx context.Context) error {
 	for n, v := range k.Certificates {
 		k.logger.Infof("Ensuring %s exists", string(n))
 		_, _, err := v.Ensure(ctx, k.KV)
 		if err != nil {
 			return fmt.Errorf("could not ensure certificate %q exists: %w", n, err)
 		}
 	}
 	_, err := k.ServiceAccountKey(ctx)
 	if err != nil {
 		return fmt.Errorf("could not ensure service account key exists: %w", err)
 	}
 	return nil
 }

 // Kubeconfig generates a kubeconfig blob for a given certificate name. The
 // same lifetime semantics as in .Certificate apply.
 func (k *PKI) Kubeconfig(ctx context.Context, name KubeCertificateName) ([]byte, error) {
 	c, ok := k.Certificates[name]
 	if !ok {
 		return nil, fmt.Errorf("no certificate %q", name)
 	}
 	return Kubeconfig(ctx, k.KV, c)
 }

 // Certificate retrieves an x509 DER-encoded (but not PEM-wrapped) key and
 // certificate for a given certificate name.
 // If the requested certificate is volatile, it will be created on demand.
 // Otherwise it will be created on etcd (if not present), and retrieved from
 // there.
 func (k *PKI) Certificate(ctx context.Context, name KubeCertificateName) (cert, key []byte, err error) {
 	c, ok := k.Certificates[name]
 	if !ok {
 		return nil, nil, fmt.Errorf("no certificate %q", name)
 	}
 	return c.Ensure(ctx, k.KV)
 }

 // Kubeconfig generates a kubeconfig blob for this certificate. The same
 // lifetime semantics as in .Ensure apply.
 func Kubeconfig(ctx context.Context, kv clientv3.KV, c *opki.Certificate) ([]byte, error) {

 	cert, key, err := c.Ensure(ctx, kv)
 	if err != nil {
 		return nil, fmt.Errorf("could not ensure certificate exists: %w", err)
 	}

 	kubeconfig := configapi.NewConfig()

 	cluster := configapi.NewCluster()
 	cluster.Server = fmt.Sprintf("https://127.0.0.1:%v", common.KubernetesAPIPort)

 	ca, err := c.Issuer.CACertificate(ctx, kv)
 	if err != nil {
 		return nil, fmt.Errorf("could not get CA certificate: %w", err)
 	}
 	if ca != nil {
 		cluster.CertificateAuthorityData = pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: ca})
 	}
 	kubeconfig.Clusters["default"] = cluster

 	authInfo := configapi.NewAuthInfo()
 	authInfo.ClientCertificateData = pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: cert})
 	authInfo.ClientKeyData = pem.EncodeToMemory(&pem.Block{Type: "PRIVATE KEY", Bytes: key})
 	kubeconfig.AuthInfos["default"] = authInfo

 	ct := configapi.NewContext()
 	ct.Cluster = "default"
 	ct.AuthInfo = "default"
 	kubeconfig.Contexts["default"] = ct

 	kubeconfig.CurrentContext = "default"
 	return clientcmd.Write(*kubeconfig)
 }

 // ServiceAccountKey retrieves (and possibly generates and stores on etcd) the
 // Kubernetes service account key. The returned data is ready to be used by
 // Kubernetes components (in PKIX form).
 func (k *PKI) ServiceAccountKey(ctx context.Context) ([]byte, error) {
 	// TODO(q3k): this should be abstracted away once we abstract away etcd
 	// access into a library with try-or-create semantics.
 	path := fmt.Sprintf("%s%s.der", etcdPrefix, serviceAccountKeyName)

 	// Try loading  key from etcd.
 	keyRes, err := k.KV.Get(ctx, path)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get key from etcd: %w", err)
 	}

 	if len(keyRes.Kvs) == 1 {
 		// Certificate and key exists in etcd, return that.
 		return keyRes.Kvs[0].Value, nil
 	}

 	// No key found - generate one.
 	keyRaw, err := rsa.GenerateKey(rand.Reader, 2048)
 	if err != nil {
 		panic(err)
 	}
 	key, err := x509.MarshalPKCS8PrivateKey(keyRaw)
 	if err != nil {
 		panic(err) // Always a programmer error
 	}

 	// Save to etcd.
 	_, err = k.KV.Put(ctx, path, string(key))
 	if err != nil {
 		err = fmt.Errorf("failed to write newly generated key: %w", err)
 	}
 	return key, nil
 }

 // VolatileKubelet returns a pair of server/client ceritficates for the Kubelet
 // to use. The certificates are volatile, meaning they are not stored in etcd,
 // and instead are regenerated any time this function is called.
 func (k *PKI) VolatileKubelet(ctx context.Context, name string) (server *opki.Certificate, client *opki.Certificate, err error) {
 	name = fmt.Sprintf("system:node:%s", name)
 	err = k.EnsureAll(ctx)
 	if err != nil {
 		err = fmt.Errorf("could not ensure certificates exist: %w", err)
 	}
 	kubeCA := k.Certificates[IdCA]
 	server = k.namespace.New(kubeCA, "", opki.Server([]string{name}, nil))
 	client = k.namespace.New(kubeCA, "", opki.Client(name, []string{"system:nodes"}))
 	return
 }

 // VolatileClient returns a client certificate for Kubernetes clients to use.
 // The generated certificate will place the user in the given groups, and with
 // a given identiy as the certificate's CN.
 func (k *PKI) VolatileClient(ctx context.Context, identity string, groups []string) (*opki.Certificate, error) {
 	if err := k.EnsureAll(ctx); err != nil {
 		return nil, fmt.Errorf("could not ensure certificates exist: %w", err)
 	}
 	kubeCA := k.Certificates[IdCA]
 	return k.namespace.New(kubeCA, "", opki.Client(identity, groups)), nil
 }
	// Copyright 2020 The Monogon Project Authors.
	//
	// SPDX-License-Identifier: Apache-2.0
	//
	// 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 pki builds upon metropolis/pkg/pki/ to provide an
	// etcd-backed implementation of all x509 PKI Certificates/CAs required to run
	// Kubernetes.
	// Most elements of the PKI are 'static' long-standing certificates/credentials
	// stored within etcd. However, this package also provides a method to generate
	// 'volatile' (in-memory) certificates/credentials for per-node Kubelets and
	// any client certificates.
	package pki

	import (
	"context"
	"crypto/rand"
	"crypto/rsa"
	"crypto/x509"
	"encoding/pem"
	"fmt"
	"net"

	"go.etcd.io/etcd/clientv3"
	"k8s.io/client-go/tools/clientcmd"
	configapi "k8s.io/client-go/tools/clientcmd/api"

	common "source.monogon.dev/metropolis/node"
	"source.monogon.dev/metropolis/pkg/logtree"
	opki "source.monogon.dev/metropolis/pkg/pki"
	)

	// KubeCertificateName is an enum-like unique name of a static Kubernetes
	// certificate. The value of the name is used as the unique part of an etcd
	// path where the certificate and key are stored.
	type KubeCertificateName string

	const (
	// The main Kubernetes CA, used to authenticate API consumers, and servers.
	IdCA KubeCertificateName = "id-ca"

	// Kubernetes apiserver server certificate.
	APIServer KubeCertificateName = "apiserver"

	// APIServer client certificate used to authenticate to kubelets.
	APIServerKubeletClient KubeCertificateName = "apiserver-kubelet-client"

	// Kubernetes Controller manager client certificate, used to authenticate
	// to the apiserver.
	ControllerManagerClient KubeCertificateName = "controller-manager-client"
	// Kubernetes Controller manager server certificate, used to run its HTTP
	// server.
	ControllerManager KubeCertificateName = "controller-manager"

	// Kubernetes Scheduler client certificate, used to authenticate to the apiserver.
	SchedulerClient KubeCertificateName = "scheduler-client"
	// Kubernetes scheduler server certificate, used to run its HTTP server.
	Scheduler KubeCertificateName = "scheduler"

	// Root-on-kube (system:masters) client certificate. Used to control the
	// apiserver (and resources) by Metropolis internally.
	Master KubeCertificateName = "master"

	// OpenAPI Kubernetes Aggregation CA.
	// https://kubernetes.io/docs/tasks/extend-kubernetes/configure-aggregation-layer/#ca-reusage-and-conflicts
	AggregationCA KubeCertificateName = "aggregation-ca"
	FrontProxyClient KubeCertificateName = "front-proxy-client"
	)

	const (
	// etcdPrefix is where all the PKI data is stored in etcd.
	etcdPrefix = "/kube-pki/"
	// serviceAccountKeyName is the etcd path part that is used to store the
	// ServiceAccount authentication secret. This is not a certificate, just an
	// RSA key.
	serviceAccountKeyName = "service-account-privkey"
	)

	// PKI manages all PKI resources required to run Kubernetes on Metropolis. It
	// contains all static certificates, which can be retrieved, or be used to
	// generate Kubeconfigs from.
	type PKI struct {
	namespace opki.Namespace
	logger logtree.LeveledLogger
	KV clientv3.KV
	Certificates map[KubeCertificateName]*opki.Certificate
	}

	func New(l logtree.LeveledLogger, kv clientv3.KV) *PKI {
	pki := PKI{
	namespace: opki.Namespaced(etcdPrefix),
	logger: l,
	KV: kv,
	Certificates: make(map[KubeCertificateName]*opki.Certificate),
	}

	make := func(i, name KubeCertificateName, template x509.Certificate) {
	pki.Certificates[name] = pki.namespace.New(pki.Certificates[i], string(name), template)
	}

	pki.Certificates[IdCA] = pki.namespace.New(opki.SelfSigned, string(IdCA), opki.CA("Metropolis Kubernetes ID CA"))
	make(IdCA, APIServer, opki.Server(
	[]string{
	"kubernetes",
	"kubernetes.default",
	"kubernetes.default.svc",
	"kubernetes.default.svc.cluster",
	"kubernetes.default.svc.cluster.local",
	"localhost",
	},
	// TODO(q3k): add service network internal apiserver address
	[]net.IP{{10, 0, 255, 1}, {127, 0, 0, 1}},
	))
	make(IdCA, APIServerKubeletClient, opki.Client("metropolis:apiserver-kubelet-client", nil))
	make(IdCA, ControllerManagerClient, opki.Client("system:kube-controller-manager", nil))
	make(IdCA, ControllerManager, opki.Server([]string{"kube-controller-manager.local"}, nil))
	make(IdCA, SchedulerClient, opki.Client("system:kube-scheduler", nil))
	make(IdCA, Scheduler, opki.Server([]string{"kube-scheduler.local"}, nil))
	make(IdCA, Master, opki.Client("metropolis:master", []string{"system:masters"}))

	pki.Certificates[AggregationCA] = pki.namespace.New(opki.SelfSigned, string(AggregationCA), opki.CA("Metropolis OpenAPI Aggregation CA"))
	make(AggregationCA, FrontProxyClient, opki.Client("front-proxy-client", nil))

	return &pki
	}

	// EnsureAll ensures that all static certificates (and the serviceaccount key)
	// are present on etcd.
	func (k *PKI) EnsureAll(ctx context.Context) error {
	for n, v := range k.Certificates {
	k.logger.Infof("Ensuring %s exists", string(n))
	_, _, err := v.Ensure(ctx, k.KV)
	if err != nil {
	return fmt.Errorf("could not ensure certificate %q exists: %w", n, err)
	}
	}
	_, err := k.ServiceAccountKey(ctx)
	if err != nil {
	return fmt.Errorf("could not ensure service account key exists: %w", err)
	}
	return nil
	}

	// Kubeconfig generates a kubeconfig blob for a given certificate name. The
	// same lifetime semantics as in .Certificate apply.
	func (k *PKI) Kubeconfig(ctx context.Context, name KubeCertificateName) ([]byte, error) {
	c, ok := k.Certificates[name]
	if !ok {
	return nil, fmt.Errorf("no certificate %q", name)
	}
	return Kubeconfig(ctx, k.KV, c)
	}

	// Certificate retrieves an x509 DER-encoded (but not PEM-wrapped) key and
	// certificate for a given certificate name.
	// If the requested certificate is volatile, it will be created on demand.
	// Otherwise it will be created on etcd (if not present), and retrieved from
	// there.
	func (k *PKI) Certificate(ctx context.Context, name KubeCertificateName) (cert, key []byte, err error) {
	c, ok := k.Certificates[name]
	if !ok {
	return nil, nil, fmt.Errorf("no certificate %q", name)
	}
	return c.Ensure(ctx, k.KV)
	}

	// Kubeconfig generates a kubeconfig blob for this certificate. The same
	// lifetime semantics as in .Ensure apply.
	func Kubeconfig(ctx context.Context, kv clientv3.KV, c *opki.Certificate) ([]byte, error) {

	cert, key, err := c.Ensure(ctx, kv)
	if err != nil {
	return nil, fmt.Errorf("could not ensure certificate exists: %w", err)
	}

	kubeconfig := configapi.NewConfig()

	cluster := configapi.NewCluster()
	cluster.Server = fmt.Sprintf("https://127.0.0.1:%v", common.KubernetesAPIPort)

	ca, err := c.Issuer.CACertificate(ctx, kv)
	if err != nil {
	return nil, fmt.Errorf("could not get CA certificate: %w", err)
	}
	if ca != nil {
	cluster.CertificateAuthorityData = pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: ca})
	}
	kubeconfig.Clusters["default"] = cluster

	authInfo := configapi.NewAuthInfo()
	authInfo.ClientCertificateData = pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: cert})
	authInfo.ClientKeyData = pem.EncodeToMemory(&pem.Block{Type: "PRIVATE KEY", Bytes: key})
	kubeconfig.AuthInfos["default"] = authInfo

	ct := configapi.NewContext()
	ct.Cluster = "default"
	ct.AuthInfo = "default"
	kubeconfig.Contexts["default"] = ct

	kubeconfig.CurrentContext = "default"
	return clientcmd.Write(*kubeconfig)
	}

	// ServiceAccountKey retrieves (and possibly generates and stores on etcd) the
	// Kubernetes service account key. The returned data is ready to be used by
	// Kubernetes components (in PKIX form).
	func (k *PKI) ServiceAccountKey(ctx context.Context) ([]byte, error) {
	// TODO(q3k): this should be abstracted away once we abstract away etcd
	// access into a library with try-or-create semantics.
	path := fmt.Sprintf("%s%s.der", etcdPrefix, serviceAccountKeyName)

	// Try loading key from etcd.
	keyRes, err := k.KV.Get(ctx, path)
	if err != nil {
	return nil, fmt.Errorf("failed to get key from etcd: %w", err)
	}

	if len(keyRes.Kvs) == 1 {
	// Certificate and key exists in etcd, return that.
	return keyRes.Kvs[0].Value, nil
	}

	// No key found - generate one.
	keyRaw, err := rsa.GenerateKey(rand.Reader, 2048)
	if err != nil {
	panic(err)
	}
	key, err := x509.MarshalPKCS8PrivateKey(keyRaw)
	if err != nil {
	panic(err) // Always a programmer error
	}

	// Save to etcd.
	_, err = k.KV.Put(ctx, path, string(key))
	if err != nil {
	err = fmt.Errorf("failed to write newly generated key: %w", err)
	}
	return key, nil
	}

	// VolatileKubelet returns a pair of server/client ceritficates for the Kubelet
	// to use. The certificates are volatile, meaning they are not stored in etcd,
	// and instead are regenerated any time this function is called.
	func (k PKI) VolatileKubelet(ctx context.Context, name string) (server opki.Certificate, client *opki.Certificate, err error) {
	name = fmt.Sprintf("system:node:%s", name)
	err = k.EnsureAll(ctx)
	if err != nil {
	err = fmt.Errorf("could not ensure certificates exist: %w", err)
	}
	kubeCA := k.Certificates[IdCA]
	server = k.namespace.New(kubeCA, "", opki.Server([]string{name}, nil))
	client = k.namespace.New(kubeCA, "", opki.Client(name, []string{"system:nodes"}))
	return
	}

	// VolatileClient returns a client certificate for Kubernetes clients to use.
	// The generated certificate will place the user in the given groups, and with
	// a given identiy as the certificate's CN.
	func (k PKI) VolatileClient(ctx context.Context, identity string, groups []string) (opki.Certificate, error) {
	if err := k.EnsureAll(ctx); err != nil {
	return nil, fmt.Errorf("could not ensure certificates exist: %w", err)
	}
	kubeCA := k.Certificates[IdCA]
	return k.namespace.New(kubeCA, "", opki.Client(identity, groups)), nil
	}