fix listener call

Allow multiple (intermediate) CA certs

.drone.yml

@@ -0,0 +1,15 @@
+---
+
+kind: pipeline
+name: fossa
+
+steps:
+- name: fossa
+  image: rancher/drone-fossa:latest
+  settings:
+    api_key:
+      from_secret: FOSSA_API_KEY
+  when:
+    instance:
+      - drone-publish.rancher.io
+

.github/renovate.json

@@ -0,0 +1,9 @@
+{
+  "extends": [
+    "github>rancher/renovate-config#release"
+  ],
+  "baseBranches": [
+    "master"
+  ],
+  "prHourlyLimit": 2
+}

.github/workflows/renovate.yml

@@ -0,0 +1,25 @@
+name: Renovate
+on:
+  workflow_dispatch:
+    inputs:
+      logLevel:
+        description: "Override default log level"
+        required: false
+        default: "info"
+        type: string
+      overrideSchedule:
+        description: "Override all schedules"
+        required: false
+        default: "false"
+        type: string
+  # Run twice in the early morning (UTC) for initial and follow up steps (create pull request and merge)
+  schedule:
+    - cron: '30 4,6 * * *'
+
+jobs:
+  call-workflow:
+    uses: rancher/renovate-config/.github/workflows/renovate.yml@release
+    with:
+      logLevel: ${{ inputs.logLevel || 'info' }}
+      overrideSchedule: ${{ github.event.inputs.overrideSchedule == 'true' && '{''schedule'':null}' || '' }}
+    secrets: inherit

cert/cert.go

@@ -33,7 +33,9 @@ import (
 	"math"
 	"math/big"
 	"net"
+	"os"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"time"
 
@@ -109,11 +111,18 @@ func NewSignedCert(cfg Config, key crypto.Signer, caCert *x509.Certificate, caKe
 	if len(cfg.Usages) == 0 {
 		return nil, errors.New("must specify at least one ExtKeyUsage")
 	}
-	var expiresAt time.Duration
+	expiresAt := duration365d
 	if cfg.ExpiresAt > 0 {
 		expiresAt = time.Duration(cfg.ExpiresAt)
 	} else {
-		expiresAt = duration365d
+		envExpirationDays := os.Getenv("CATTLE_NEW_SIGNED_CERT_EXPIRATION_DAYS")
+		if envExpirationDays != "" {
+			if envExpirationDaysInt, err := strconv.Atoi(envExpirationDays); err != nil {
+				logrus.Infof("[NewSignedCert] expiration days from ENV (%s) could not be converted to int (falling back to default value: %d)", envExpirationDays, expiresAt)
+			} else {
+				expiresAt = time.Hour * 24 * time.Duration(envExpirationDaysInt)
+			}
+		}
 	}
 
 	certTmpl := x509.Certificate{

factory/ca.go

@@ -25,18 +25,28 @@ func GenCA() (*x509.Certificate, crypto.Signer, error) {
 	return caCert, caKey, nil
 }
 
+// Deprecated: Use LoadOrGenCAChain instead as it supports intermediate CAs
 func LoadOrGenCA() (*x509.Certificate, crypto.Signer, error) {
-	cert, key, err := loadCA()
-	if err == nil {
-		return cert, key, nil
-	}
-
-	cert, key, err = GenCA()
+	chain, signer, err := LoadOrGenCAChain()
 	if err != nil {
 		return nil, nil, err
 	}
+	return chain[0], signer, err
+}
 
-	certBytes, keyBytes, err := Marshal(cert, key)
+func LoadOrGenCAChain() ([]*x509.Certificate, crypto.Signer, error) {
+	certs, key, err := loadCA()
+	if err == nil {
+		return certs, key, nil
+	}
+
+	cert, key, err := GenCA()
+	if err != nil {
+		return nil, nil, err
+	}
+	certs = []*x509.Certificate{cert}
+
+	certBytes, keyBytes, err := MarshalChain(key, certs...)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -53,14 +63,22 @@ func LoadOrGenCA() (*x509.Certificate, crypto.Signer, error) {
 		return nil, nil, err
 	}
 
-	return cert, key, nil
+	return certs, key, nil
 }
 
-func loadCA() (*x509.Certificate, crypto.Signer, error) {
-	return LoadCerts("./certs/ca.pem", "./certs/ca.key")
+func loadCA() ([]*x509.Certificate, crypto.Signer, error) {
+	return LoadCertsChain("./certs/ca.pem", "./certs/ca.key")
 }
 
 func LoadCA(caPem, caKey []byte) (*x509.Certificate, crypto.Signer, error) {
+	chain, signer, err := LoadCAChain(caPem, caKey)
+	if err != nil {
+		return nil, nil, err
+	}
+	return chain[0], signer, nil
+}
+
+func LoadCAChain(caPem, caKey []byte) ([]*x509.Certificate, crypto.Signer, error) {
 	key, err := cert.ParsePrivateKeyPEM(caKey)
 	if err != nil {
 		return nil, nil, err
@@ -70,15 +88,24 @@ func LoadCA(caPem, caKey []byte) (*x509.Certificate, crypto.Signer, error) {
 		return nil, nil, fmt.Errorf("key is not a crypto.Signer")
 	}
 
-	cert, err := ParseCertPEM(caPem)
+	certs, err := cert.ParseCertsPEM(caPem)
 	if err != nil {
 		return nil, nil, err
 	}
 
-	return cert, signer, nil
+	return certs, signer, nil
 }
 
+// Deprecated: Use LoadCertsChain instead as it supports intermediate CAs
 func LoadCerts(certFile, keyFile string) (*x509.Certificate, crypto.Signer, error) {
+	chain, signer, err := LoadCertsChain(certFile, keyFile)
+	if err != nil {
+		return nil, nil, err
+	}
+	return chain[0], signer, err
+}
+
+func LoadCertsChain(certFile, keyFile string) ([]*x509.Certificate, crypto.Signer, error) {
 	caPem, err := ioutil.ReadFile(certFile)
 	if err != nil {
 		return nil, nil, err
@@ -88,5 +115,5 @@ func LoadCerts(certFile, keyFile string) (*x509.Certificate, crypto.Signer, erro
 		return nil, nil, err
 	}
 
-	return LoadCA(caPem, caKey)
+	return LoadCAChain(caPem, caKey)
 }

factory/gen.go

@@ -15,6 +15,7 @@ import (
 	"regexp"
 	"sort"
 	"strings"
+	"time"
 
 	"github.com/rancher/dynamiclistener/cert"
 	"github.com/sirupsen/logrus"
@@ -32,11 +33,12 @@ var (
 )
 
 type TLS struct {
-	CACert       *x509.Certificate
-	CAKey        crypto.Signer
-	CN           string
-	Organization []string
-	FilterCN     func(...string) []string
+	CACert              []*x509.Certificate
+	CAKey               crypto.Signer
+	CN                  string
+	Organization        []string
+	FilterCN            func(...string) []string
+	ExpirationDaysCheck int
 }
 
 func cns(secret *v1.Secret) (cns []string) {
@@ -72,7 +74,8 @@ func collectCNs(secret *v1.Secret) (domains []string, ips []net.IP, err error) {
 
 // Merge combines the SAN lists from the target and additional Secrets, and
 // returns a potentially modified Secret, along with a bool indicating if the
-// returned Secret is not the same as the target Secret.
+// returned Secret is not the same as the target Secret. Secrets with expired
+// certificates will never be returned.
 //
 // If the merge would not add any CNs to the additional Secret, the additional
 // Secret is returned, to allow for certificate rotation/regeneration.
@@ -93,17 +96,17 @@ func (t *TLS) Merge(target, additional *v1.Secret) (*v1.Secret, bool, error) {
 
 	// if the additional secret already has all the CNs, use it in preference to the
 	// current one. This behavior is required to allow for renewal or regeneration.
-	if !NeedsUpdate(0, additional, mergedCNs...) {
+	if !NeedsUpdate(0, additional, mergedCNs...) && !t.IsExpired(additional) {
 		return additional, true, nil
 	}
 
 	// if the target secret already has all the CNs, continue using it. The additional
 	// cert had only a subset of the current CNs, so nothing needs to be added.
-	if !NeedsUpdate(0, target, mergedCNs...) {
+	if !NeedsUpdate(0, target, mergedCNs...) && !t.IsExpired(target) {
 		return target, false, nil
 	}
 
-	// neither cert currently has all the necessary CNs; generate a new one.
+	// neither cert currently has all the necessary CNs or is unexpired; generate a new one.
 	return t.generateCert(target, mergedCNs...)
 }
 
@@ -175,7 +178,7 @@ func (t *TLS) generateCert(secret *v1.Secret, cn ...string) (*v1.Secret, bool, e
 		return nil, false, err
 	}
 
-	keyBytes, certBytes, err := MarshalChain(privateKey, newCert, t.CACert)
+	keyBytes, certBytes, err := MarshalChain(privateKey, append([]*x509.Certificate{newCert}, t.CACert...)...)
 	if err != nil {
 		return nil, false, err
 	}
@@ -191,6 +194,21 @@ func (t *TLS) generateCert(secret *v1.Secret, cn ...string) (*v1.Secret, bool, e
 	return secret, true, nil
 }
 
+func (t *TLS) IsExpired(secret *v1.Secret) bool {
+	certsPem := secret.Data[v1.TLSCertKey]
+	if len(certsPem) == 0 {
+		return false
+	}
+
+	certificates, err := cert.ParseCertsPEM(certsPem)
+	if err != nil || len(certificates) == 0 {
+		return false
+	}
+
+	expirationDays := time.Duration(t.ExpirationDaysCheck) * time.Hour * 24
+	return time.Now().Add(expirationDays).After(certificates[0].NotAfter)
+}
+
 func (t *TLS) Verify(secret *v1.Secret) error {
 	certsPem := secret.Data[v1.TLSCertKey]
 	if len(certsPem) == 0 {
@@ -208,14 +226,16 @@ func (t *TLS) Verify(secret *v1.Secret) error {
 			x509.ExtKeyUsageAny,
 		},
 	}
-	verifyOpts.Roots.AddCert(t.CACert)
+	for _, c := range t.CACert {
+		verifyOpts.Roots.AddCert(c)
+	}
 
 	_, err = certificates[0].Verify(verifyOpts)
 	return err
 }
 
 func (t *TLS) newCert(domains []string, ips []net.IP, privateKey crypto.Signer) (*x509.Certificate, error) {
-	return NewSignedCert(privateKey, t.CACert, t.CAKey, t.CN, t.Organization, domains, ips)
+	return NewSignedCert(privateKey, t.CACert[0], t.CAKey, t.CN, t.Organization, domains, ips)
 }
 
 func populateCN(secret *v1.Secret, cn ...string) *v1.Secret {

go.mod

@@ -1,12 +1,63 @@
 module github.com/rancher/dynamiclistener
 
-go 1.12
+go 1.20
 
 require (
-	github.com/rancher/wrangler v0.8.9
-	github.com/sirupsen/logrus v1.4.2
-	golang.org/x/crypto v0.0.0-20210322153248-0c34fe9e7dc2
-	k8s.io/api v0.18.8
-	k8s.io/apimachinery v0.18.8
-	k8s.io/client-go v0.18.8
+	github.com/rancher/wrangler v1.1.1-0.20230831050635-df1bd5aae9df
+	github.com/sirupsen/logrus v1.9.3
+	github.com/stretchr/testify v1.8.4
+	golang.org/x/crypto v0.11.0
+	k8s.io/api v0.27.4
+	k8s.io/apimachinery v0.27.4
+	k8s.io/client-go v0.27.4
+)
+
+require (
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.1.2 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/emicklei/go-restful/v3 v3.9.0 // indirect
+	github.com/evanphx/json-patch v4.12.0+incompatible // indirect
+	github.com/go-logr/logr v1.2.3 // indirect
+	github.com/go-openapi/jsonpointer v0.19.6 // indirect
+	github.com/go-openapi/jsonreference v0.20.1 // indirect
+	github.com/go-openapi/swag v0.22.3 // indirect
+	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/golang/protobuf v1.5.3 // indirect
+	github.com/google/gnostic v0.5.7-v3refs // indirect
+	github.com/google/go-cmp v0.5.9 // indirect
+	github.com/google/gofuzz v1.2.0 // indirect
+	github.com/google/uuid v1.3.0 // indirect
+	github.com/josharian/intern v1.0.0 // indirect
+	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/mailru/easyjson v0.7.7 // indirect
+	github.com/matttproud/golang_protobuf_extensions v1.0.2 // indirect
+	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
+	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/prometheus/client_golang v1.14.0 // indirect
+	github.com/prometheus/client_model v0.3.0 // indirect
+	github.com/prometheus/common v0.37.0 // indirect
+	github.com/prometheus/procfs v0.8.0 // indirect
+	github.com/rancher/lasso v0.0.0-20230830164424-d684fdeb6f29 // indirect
+	golang.org/x/net v0.12.0 // indirect
+	golang.org/x/oauth2 v0.10.0 // indirect
+	golang.org/x/sync v0.1.0 // indirect
+	golang.org/x/sys v0.10.0 // indirect
+	golang.org/x/term v0.10.0 // indirect
+	golang.org/x/text v0.11.0 // indirect
+	golang.org/x/time v0.3.0 // indirect
+	google.golang.org/appengine v1.6.7 // indirect
+	google.golang.org/protobuf v1.31.0 // indirect
+	gopkg.in/inf.v0 v0.9.1 // indirect
+	gopkg.in/yaml.v2 v2.4.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+	k8s.io/klog/v2 v2.90.1 // indirect
+	k8s.io/kube-openapi v0.0.0-20230501164219-8b0f38b5fd1f // indirect
+	k8s.io/utils v0.0.0-20230209194617-a36077c30491 // indirect
+	sigs.k8s.io/json v0.0.0-20221116044647-bc3834ca7abd // indirect
+	sigs.k8s.io/structured-merge-diff/v4 v4.2.3 // indirect
+	sigs.k8s.io/yaml v1.3.0 // indirect
 )

listener.go

@@ -7,7 +7,6 @@ import (
 	"crypto/x509"
 	"net"
 	"net/http"
-	"runtime"
 	"strings"
 	"sync"
 	"time"
@@ -35,7 +34,12 @@ type SetFactory interface {
 	SetFactory(tls TLSFactory)
 }
 
+// Deprecated: Use NewListenerWithChain instead as it supports intermediate CAs
 func NewListener(l net.Listener, storage TLSStorage, caCert *x509.Certificate, caKey crypto.Signer, config Config) (net.Listener, http.Handler, error) {
+	return NewListenerWithChain(l, storage, []*x509.Certificate{caCert}, caKey, config)
+}
+
+func NewListenerWithChain(l net.Listener, storage TLSStorage, caCert []*x509.Certificate, caKey crypto.Signer, config Config) (net.Listener, http.Handler, error) {
 	if config.CN == "" {
 		config.CN = "dynamic"
 	}
@@ -45,16 +49,21 @@ func NewListener(l net.Listener, storage TLSStorage, caCert *x509.Certificate, c
 	if config.TLSConfig == nil {
 		config.TLSConfig = &tls.Config{}
 	}
+	if config.ExpirationDaysCheck == 0 {
+		config.ExpirationDaysCheck = 90
+	}
 
 	dynamicListener := &listener{
 		factory: &factory.TLS{
-			CACert:       caCert,
-			CAKey:        caKey,
-			CN:           config.CN,
-			Organization: config.Organization,
-			FilterCN:     allowDefaultSANs(config.SANs, config.FilterCN),
+			CACert:              caCert,
+			CAKey:               caKey,
+			CN:                  config.CN,
+			Organization:        config.Organization,
+			FilterCN:            allowDefaultSANs(config.SANs, config.FilterCN),
+			ExpirationDaysCheck: config.ExpirationDaysCheck,
 		},
 		Listener:  l,
+		certReady: make(chan struct{}),
 		storage:   &nonNil{storage: storage},
 		sans:      config.SANs,
 		maxSANs:   config.MaxSANs,
@@ -82,10 +91,6 @@ func NewListener(l net.Listener, storage TLSStorage, caCert *x509.Certificate, c
 		}
 	}
 
-	if config.ExpirationDaysCheck == 0 {
-		config.ExpirationDaysCheck = 30
-	}
-
 	tlsListener := tls.NewListener(dynamicListener.WrapExpiration(config.ExpirationDaysCheck), dynamicListener.tlsConfig)
 
 	return tlsListener, dynamicListener.cacheHandler(), nil
@@ -155,6 +160,7 @@ type listener struct {
 	version   string
 	tlsConfig *tls.Config
 	cert      *tls.Certificate
+	certReady chan struct{}
 	sans      []string
 	maxSANs   int
 	init      sync.Once
@@ -163,9 +169,12 @@ type listener struct {
 func (l *listener) WrapExpiration(days int) net.Listener {
 	ctx, cancel := context.WithCancel(context.Background())
 	go func() {
-		// busy-wait for certificate preload to complete
-		for l.cert == nil {
-			runtime.Gosched()
+
+		// wait for cert to be set, this will unblock when the channel is closed
+		select {
+		case <-ctx.Done():
+			return
+		case <-l.certReady:
 		}
 
 		for {
@@ -346,8 +355,20 @@ func (l *listener) getCertificate(hello *tls.ClientHelloInfo) (*tls.Certificate,
 			return nil, err
 		}
 	}
-
-	return l.loadCert(newConn)
+	connCert, err := l.loadCert(newConn)
+	if connCert != nil && err == nil && newConn != nil && l.conns != nil {
+		// if we were successfully able to load a cert and are closing connections on cert changes, mark newConn ready
+		// this will allow us to close the connection if a future connection forces the cert to re-load
+		wrapper, ok := newConn.(*closeWrapper)
+		if !ok {
+			logrus.Debugf("will not mark non-close wrapper connection from %s to %s as ready", newConn.RemoteAddr(), newConn.LocalAddr())
+			return connCert, err
+		}
+		l.connLock.Lock()
+		l.conns[wrapper.id].ready = true
+		l.connLock.Unlock()
+	}
+	return connCert, err
 }
 
 func (l *listener) updateCert(cn ...string) error {
@@ -434,11 +455,15 @@ func (l *listener) loadCert(currentConn net.Conn) (*tls.Certificate, error) {
 			}
 			_ = conn.close()
 		}
-		l.conns[currentConn.(*closeWrapper).id].ready = true
 		l.connLock.Unlock()
 	}
 
+	// we can only close the ready channel once when the cert is first assigned
+	canClose := l.cert == nil
 	l.cert = &cert
+	if canClose {
+		close(l.certReady)
+	}
 	l.version = secret.ResourceVersion
 	return l.cert, nil
 }

listener_test.go

@@ -0,0 +1,225 @@
+package dynamiclistener
+
+import (
+	"crypto/tls"
+	"net"
+	"testing"
+	"time"
+
+	"github.com/rancher/dynamiclistener/factory"
+	"github.com/stretchr/testify/assert"
+	v1 "k8s.io/api/core/v1"
+	apiError "k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+)
+
+func Test_getCertificate(t *testing.T) {
+	beforeKey, beforeCert, err := newCertificate()
+	assert.NoError(t, err, "Error when setting up test - unable to construct before key for test")
+	beforeTLSCert, err := tls.X509KeyPair(beforeCert, beforeKey)
+	assert.NoError(t, err, "Error when setting up test - unable to convert before to tls.Certificate")
+	afterKey, afterCert, err := newCertificate()
+	assert.NoError(t, err, "Error when setting up test - unable to construct after key for test")
+	afterTLSCert, err := tls.X509KeyPair(afterCert, afterKey)
+	assert.NoError(t, err, "Error when setting up test - unable to convert after to tls.Certificate")
+	tests := []struct {
+		// input test vars
+		name          string
+		secret        *v1.Secret
+		secretErr     error
+		cachedCert    *tls.Certificate
+		cachedVersion string
+		currentConn   *closeWrapper
+		otherConns    map[int]*closeWrapper
+
+		// output/result test vars
+		closedConns  []int
+		expectedCert *tls.Certificate
+		wantError    bool
+	}{
+		{
+			name:   "no secret found",
+			secret: nil,
+			secretErr: apiError.NewNotFound(schema.GroupResource{
+				Group:    "",
+				Resource: "Secret",
+			}, "testSecret"),
+			currentConn: &closeWrapper{id: 0},
+			otherConns:  map[int]*closeWrapper{},
+
+			expectedCert: nil,
+			wantError:    true,
+		},
+		{
+			name: "secret found, and is up to date",
+			secret: &v1.Secret{
+				ObjectMeta: metav1.ObjectMeta{
+					ResourceVersion: "1",
+					Name:            "testSecret",
+					Namespace:       "test",
+				},
+				Data: map[string][]byte{
+					v1.TLSCertKey:       beforeCert,
+					v1.TLSPrivateKeyKey: beforeKey,
+				},
+			},
+			cachedVersion: "1",
+			cachedCert:    &beforeTLSCert,
+			currentConn:   &closeWrapper{id: 0},
+			otherConns:    map[int]*closeWrapper{},
+
+			expectedCert: &beforeTLSCert,
+			wantError:    false,
+		},
+		{
+			name: "secret found, is not up to date, but k8s secret is not valid",
+			secret: &v1.Secret{
+				ObjectMeta: metav1.ObjectMeta{
+					ResourceVersion: "2",
+					Name:            "testSecret",
+					Namespace:       "test",
+				},
+				Data: map[string][]byte{
+					v1.TLSPrivateKeyKey: []byte("strawberry"),
+				},
+			},
+			cachedVersion: "1",
+			cachedCert:    &beforeTLSCert,
+			currentConn:   &closeWrapper{id: 0},
+			otherConns:    map[int]*closeWrapper{},
+
+			expectedCert: &beforeTLSCert,
+			wantError:    false,
+		},
+		{
+			name: "secret found, but is not up to date",
+			secret: &v1.Secret{
+				ObjectMeta: metav1.ObjectMeta{
+					ResourceVersion: "2",
+					Name:            "testSecret",
+					Namespace:       "test",
+				},
+				Data: map[string][]byte{
+					v1.TLSCertKey:       afterCert,
+					v1.TLSPrivateKeyKey: afterKey,
+				},
+			},
+			cachedVersion: "1",
+			cachedCert:    &beforeTLSCert,
+			currentConn:   &closeWrapper{id: 0},
+			otherConns:    map[int]*closeWrapper{},
+
+			expectedCert: &afterTLSCert,
+			wantError:    false,
+		},
+		{
+			name: "secret found, is not up to date, and we have conns using current cert",
+			secret: &v1.Secret{
+				ObjectMeta: metav1.ObjectMeta{
+					ResourceVersion: "2",
+					Name:            "testSecret",
+					Namespace:       "test",
+				},
+				Data: map[string][]byte{
+					v1.TLSCertKey:       afterCert,
+					v1.TLSPrivateKeyKey: afterKey,
+				},
+			},
+			cachedVersion: "1",
+			cachedCert:    &beforeTLSCert,
+			currentConn:   &closeWrapper{id: 0},
+			otherConns: map[int]*closeWrapper{
+				1: {
+					id:    1,
+					ready: false,
+					Conn:  &fakeConn{},
+				},
+				2: {
+					id:    2,
+					ready: true,
+					Conn:  &fakeConn{},
+				},
+			},
+
+			closedConns:  []int{2},
+			expectedCert: &afterTLSCert,
+			wantError:    false,
+		},
+	}
+	for i := range tests {
+		test := tests[i]
+		t.Run(test.name, func(t *testing.T) {
+			t.Parallel()
+			testConns := test.otherConns
+			if testConns != nil {
+				testConns[test.currentConn.id] = test.currentConn
+				// make sure our conn is listed as one of the current connections
+			}
+			l := listener{
+				cert:    test.cachedCert,
+				version: test.cachedVersion,
+				storage: &MockTLSStorage{
+					Secret:    test.secret,
+					SecretErr: test.secretErr,
+				},
+				conns: testConns,
+			}
+			for _, conn := range testConns {
+				conn.l = &l
+			}
+			newCert, err := l.getCertificate(&tls.ClientHelloInfo{Conn: test.currentConn})
+			if test.wantError {
+				assert.Errorf(t, err, "expected an error but none was provdied")
+			} else {
+				assert.NoError(t, err, "did not expect an error but got one")
+			}
+			assert.Equal(t, test.expectedCert, newCert, "expected cert did not match actual cert")
+			if test.expectedCert != nil && test.wantError == false && test.currentConn != nil && test.otherConns != nil {
+				assert.True(t, test.currentConn.ready, "expected connection to be ready but it was not")
+			} else {
+				if test.currentConn != nil {
+					assert.False(t, test.currentConn.ready, "did not expect connection to be ready")
+				}
+			}
+			for _, closedConn := range test.closedConns {
+				_, ok := l.conns[closedConn]
+				assert.False(t, ok, "closed conns should not be found")
+			}
+		})
+	}
+}
+
+func newCertificate() ([]byte, []byte, error) {
+	cert, key, err := factory.GenCA()
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return factory.MarshalChain(key, cert)
+}
+
+type MockTLSStorage struct {
+	Secret    *v1.Secret
+	SecretErr error
+}
+
+func (m *MockTLSStorage) Get() (*v1.Secret, error) {
+	return m.Secret, m.SecretErr
+}
+
+func (m *MockTLSStorage) Update(secret *v1.Secret) error {
+	panic("Not implemented")
+}
+
+// adapted from k8s.io/apimachinery@v0.18.8/pkg/util.proxy/ugradeaware_test.go
+type fakeConn struct{}
+
+func (f *fakeConn) Read([]byte) (int, error)        { return 0, nil }
+func (f *fakeConn) Write([]byte) (int, error)       { return 0, nil }
+func (f *fakeConn) Close() error                    { return nil }
+func (fakeConn) LocalAddr() net.Addr                { return nil }
+func (fakeConn) RemoteAddr() net.Addr               { return nil }
+func (fakeConn) SetDeadline(t time.Time) error      { return nil }
+func (fakeConn) SetReadDeadline(t time.Time) error  { return nil }
+func (fakeConn) SetWriteDeadline(t time.Time) error { return nil }

server/server.go

@@ -21,6 +21,8 @@ import (
 )
 
 type ListenOpts struct {
+	CAChain []*x509.Certificate
+	// Deprecated: Use CAChain instead
 	CA                *x509.Certificate
 	CAKey             crypto.Signer
 	Storage           dynamiclistener.TLSStorage
@@ -132,7 +134,7 @@ func getTLSListener(ctx context.Context, tcp net.Listener, handler http.Handler,
 		return nil, nil, err
 	}
 
-	listener, dynHandler, err := dynamiclistener.NewListener(tcp, storage, caCert, caKey, opts.TLSListenerConfig)
+	listener, dynHandler, err := dynamiclistener.NewListenerWithChain(tcp, storage, caCert, caKey, opts.TLSListenerConfig)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -140,13 +142,17 @@ func getTLSListener(ctx context.Context, tcp net.Listener, handler http.Handler,
 	return listener, wrapHandler(dynHandler, handler), nil
 }
 
-func getCA(opts ListenOpts) (*x509.Certificate, crypto.Signer, error) {
-	if opts.CA != nil && opts.CAKey != nil {
-		return opts.CA, opts.CAKey, nil
+func getCA(opts ListenOpts) ([]*x509.Certificate, crypto.Signer, error) {
+	if opts.CAKey != nil {
+		if opts.CAChain != nil {
+			return opts.CAChain, opts.CAKey, nil
+		} else if opts.CA != nil {
+			return []*x509.Certificate{opts.CA}, opts.CAKey, nil
+		}
 	}
 
 	if opts.Secrets == nil {
-		return factory.LoadOrGenCA()
+		return factory.LoadOrGenCAChain()
 	}
 
 	if opts.CAName == "" {
@@ -161,7 +167,7 @@ func getCA(opts ListenOpts) (*x509.Certificate, crypto.Signer, error) {
 		opts.CANamespace = "kube-system"
 	}
 
-	return kubernetes.LoadOrGenCA(opts.Secrets, opts.CANamespace, opts.CAName)
+	return kubernetes.LoadOrGenCAChain(opts.Secrets, opts.CANamespace, opts.CAName)
 }
 
 func newStorage(ctx context.Context, opts ListenOpts) dynamiclistener.TLSStorage {

storage/kubernetes/ca.go

@@ -11,12 +11,21 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
 
+// Deprecated: Use LoadOrGenCAChain instead as it supports intermediate CAs
 func LoadOrGenCA(secrets v1controller.SecretClient, namespace, name string) (*x509.Certificate, crypto.Signer, error) {
+	chain, signer, err := LoadOrGenCAChain(secrets, namespace, name)
+	if err != nil {
+		return nil, nil, err
+	}
+	return chain[0], signer, err
+}
+
+func LoadOrGenCAChain(secrets v1controller.SecretClient, namespace, name string) ([]*x509.Certificate, crypto.Signer, error) {
 	secret, err := getSecret(secrets, namespace, name)
 	if err != nil {
 		return nil, nil, err
 	}
-	return factory.LoadCA(secret.Data[v1.TLSCertKey], secret.Data[v1.TLSPrivateKeyKey])
+	return factory.LoadCAChain(secret.Data[v1.TLSCertKey], secret.Data[v1.TLSPrivateKeyKey])
 }
 
 func LoadOrGenClient(secrets v1controller.SecretClient, namespace, name, cn string, ca *x509.Certificate, key crypto.Signer) (*x509.Certificate, crypto.Signer, error) {