Merge pull request #112017 from enj/enj/i/exec_tls_cache

exec auth: support TLS config caching

staging/src/k8s.io/client-go/plugin/pkg/client/auth/exec/exec.go

@@ -199,7 +199,6 @@ func newAuthenticator(c *cache, isTerminalFunc func(int) bool, config *api.ExecC
 		now:             time.Now,
 		environ:         os.Environ,
 
-		defaultDialer: defaultDialer,
 		connTracker: connTracker,
 	}
 
@@ -207,6 +206,11 @@ func newAuthenticator(c *cache, isTerminalFunc func(int) bool, config *api.ExecC
 		a.env = append(a.env, env.Name+"="+env.Value)
 	}
 
+	// these functions are made comparable and stored in the cache so that repeated clientset
+	// construction with the same rest.Config results in a single TLS cache and Authenticator
+	a.getCert = &transport.GetCertHolder{GetCert: a.cert}
+	a.dial = &transport.DialHolder{Dial: defaultDialer.DialContext}
+
 	return c.put(key, a), nil
 }
 
@@ -261,8 +265,6 @@ type Authenticator struct {
 	now             func() time.Time
 	environ         func() []string
 
-	// defaultDialer is used for clients which don't specify a custom dialer
-	defaultDialer *connrotation.Dialer
 	// connTracker tracks all connections opened that we need to close when rotating a client certificate
 	connTracker *connrotation.ConnectionTracker
 
@@ -273,6 +275,12 @@ type Authenticator struct {
 	mu          sync.Mutex
 	cachedCreds *credentials
 	exp         time.Time
+
+	// getCert makes Authenticator.cert comparable to support TLS config caching
+	getCert *transport.GetCertHolder
+	// dial is used for clients which do not specify a custom dialer
+	// it is comparable to support TLS config caching
+	dial *transport.DialHolder
 }
 
 type credentials struct {
@@ -300,17 +308,19 @@ func (a *Authenticator) UpdateTransportConfig(c *transport.Config) error {
 	if c.HasCertCallback() {
 		return errors.New("can't add TLS certificate callback: transport.Config.TLS.GetCert already set")
 	}
-	c.TLS.GetCert = a.cert
+	c.TLS.GetCert = a.getCert.GetCert
+	c.TLS.GetCertHolder = a.getCert // comparable for TLS config caching
 
-	var d *connrotation.Dialer
 	if c.Dial != nil {
 		// if c has a custom dialer, we have to wrap it
-		d = connrotation.NewDialerWithTracker(c.Dial, a.connTracker)
-	} else {
-		d = a.defaultDialer
-	}
-
+		// TLS config caching is not supported for this config
+		d := connrotation.NewDialerWithTracker(c.Dial, a.connTracker)
 		c.Dial = d.DialContext
+		c.DialHolder = nil
+	} else {
+		c.Dial = a.dial.Dial
+		c.DialHolder = a.dial // comparable for TLS config caching
+	}
 
 	return nil
 }

staging/src/k8s.io/client-go/plugin/pkg/client/auth/exec/exec_cache_test.go

@@ -0,0 +1,106 @@
+/*
+Copyright 2022 The Kubernetes 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 exec_test // separate package to prevent circular import
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	utilnet "k8s.io/apimachinery/pkg/util/net"
+	clientset "k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/rest"
+	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
+)
+
+// TestExecTLSCache asserts the semantics of the TLS cache when exec auth is used.
+//
+// In particular, when:
+//   - multiple identical rest configs exist as distinct objects, and
+//   - these rest configs use exec auth, and
+//   - these rest configs are used to create distinct clientsets, then
+//
+// the underlying TLS config is shared between those clientsets.
+func TestExecTLSCache(t *testing.T) {
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	t.Cleanup(cancel)
+
+	config1 := &rest.Config{
+		Host: "https://localhost",
+		ExecProvider: &clientcmdapi.ExecConfig{
+			Command:         "./testdata/test-plugin.sh",
+			APIVersion:      "client.authentication.k8s.io/v1",
+			InteractiveMode: clientcmdapi.IfAvailableExecInteractiveMode,
+		},
+	}
+	client1 := clientset.NewForConfigOrDie(config1)
+
+	config2 := &rest.Config{
+		Host: "https://localhost",
+		ExecProvider: &clientcmdapi.ExecConfig{
+			Command:         "./testdata/test-plugin.sh",
+			APIVersion:      "client.authentication.k8s.io/v1",
+			InteractiveMode: clientcmdapi.IfAvailableExecInteractiveMode,
+		},
+	}
+	client2 := clientset.NewForConfigOrDie(config2)
+
+	config3 := &rest.Config{
+		Host: "https://localhost",
+		ExecProvider: &clientcmdapi.ExecConfig{
+			Command:         "./testdata/test-plugin.sh",
+			Args:            []string{"make this exec auth different"},
+			APIVersion:      "client.authentication.k8s.io/v1",
+			InteractiveMode: clientcmdapi.IfAvailableExecInteractiveMode,
+		},
+	}
+	client3 := clientset.NewForConfigOrDie(config3)
+
+	_, _ = client1.CoreV1().Nodes().List(ctx, metav1.ListOptions{})
+	_, _ = client2.CoreV1().Namespaces().List(ctx, metav1.ListOptions{})
+	_, _ = client3.CoreV1().PersistentVolumes().List(ctx, metav1.ListOptions{})
+
+	rt1 := client1.RESTClient().(*rest.RESTClient).Client.Transport
+	rt2 := client2.RESTClient().(*rest.RESTClient).Client.Transport
+	rt3 := client3.RESTClient().(*rest.RESTClient).Client.Transport
+
+	tlsConfig1, err := utilnet.TLSClientConfig(rt1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	tlsConfig2, err := utilnet.TLSClientConfig(rt2)
+	if err != nil {
+		t.Fatal(err)
+	}
+	tlsConfig3, err := utilnet.TLSClientConfig(rt3)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if tlsConfig1 == nil || tlsConfig2 == nil || tlsConfig3 == nil {
+		t.Fatal("expected non-nil TLS configs")
+	}
+
+	if tlsConfig1 != tlsConfig2 {
+		t.Fatal("expected the same TLS config for matching exec config via rest config")
+	}
+
+	if tlsConfig1 == tlsConfig3 {
+		t.Fatal("expected different TLS config for non-matching exec config via rest config")
+	}
+}

staging/src/k8s.io/client-go/transport/cache.go

@@ -17,6 +17,7 @@ limitations under the License.
 package transport
 
 import (
+	"context"
 	"fmt"
 	"net"
 	"net/http"
@@ -55,6 +56,9 @@ type tlsCacheKey struct {
 	serverName         string
 	nextProtos         string
 	disableCompression bool
+	// these functions are wrapped to allow them to be used as map keys
+	getCert *GetCertHolder
+	dial    *DialHolder
 }
 
 func (t tlsCacheKey) String() string {
@@ -62,7 +66,8 @@ func (t tlsCacheKey) String() string {
 	if len(t.keyData) > 0 {
 		keyText = "<redacted>"
 	}
-	return fmt.Sprintf("insecure:%v, caData:%#v, certData:%#v, keyData:%s, serverName:%s, disableCompression:%t", t.insecure, t.caData, t.certData, keyText, t.serverName, t.disableCompression)
+	return fmt.Sprintf("insecure:%v, caData:%#v, certData:%#v, keyData:%s, serverName:%s, disableCompression:%t, getCert:%p, dial:%p",
+		t.insecure, t.caData, t.certData, keyText, t.serverName, t.disableCompression, t.getCert, t.dial)
 }
 
 func (c *tlsTransportCache) get(config *Config) (http.RoundTripper, error) {
@@ -92,8 +97,10 @@ func (c *tlsTransportCache) get(config *Config) (http.RoundTripper, error) {
 		return http.DefaultTransport, nil
 	}
 
-	dial := config.Dial
-	if dial == nil {
+	var dial func(ctx context.Context, network, address string) (net.Conn, error)
+	if config.Dial != nil {
+		dial = config.Dial
+	} else {
 		dial = (&net.Dialer{
 			Timeout:   30 * time.Second,
 			KeepAlive: 30 * time.Second,
@@ -138,10 +145,18 @@ func tlsConfigKey(c *Config) (tlsCacheKey, bool, error) {
 		return tlsCacheKey{}, false, err
 	}
 
-	if c.TLS.GetCert != nil || c.Dial != nil || c.Proxy != nil {
+	if c.Proxy != nil {
 		// cannot determine equality for functions
 		return tlsCacheKey{}, false, nil
 	}
+	if c.Dial != nil && c.DialHolder == nil {
+		// cannot determine equality for dial function that doesn't have non-nil DialHolder set as well
+		return tlsCacheKey{}, false, nil
+	}
+	if c.TLS.GetCert != nil && c.TLS.GetCertHolder == nil {
+		// cannot determine equality for getCert function that doesn't have non-nil GetCertHolder set as well
+		return tlsCacheKey{}, false, nil
+	}
 
 	k := tlsCacheKey{
 		insecure:           c.TLS.Insecure,
@@ -149,6 +164,8 @@ func tlsConfigKey(c *Config) (tlsCacheKey, bool, error) {
 		serverName:         c.TLS.ServerName,
 		nextProtos:         strings.Join(c.TLS.NextProtos, ","),
 		disableCompression: c.DisableCompression,
+		getCert:            c.TLS.GetCertHolder,
+		dial:               c.DialHolder,
 	}
 
 	if c.TLS.ReloadTLSFiles {

staging/src/k8s.io/client-go/transport/cache_test.go

@@ -21,6 +21,7 @@ import (
 	"crypto/tls"
 	"net"
 	"net/http"
+	"net/url"
 	"testing"
 )
 
@@ -58,16 +59,24 @@ func TestTLSConfigKey(t *testing.T) {
 				t.Errorf("Expected identical cache keys for %q and %q, got:\n\t%s\n\t%s", nameA, nameB, keyA, keyB)
 				continue
 			}
+			if keyA != (tlsCacheKey{}) {
+				t.Errorf("Expected empty cache keys for %q and %q, got:\n\t%s\n\t%s", nameA, nameB, keyA, keyB)
+				continue
+			}
 		}
 	}
 
 	// Make sure config fields that affect the tls config affect the cache key
 	dialer := net.Dialer{}
 	getCert := func() (*tls.Certificate, error) { return nil, nil }
+	getCertHolder := &GetCertHolder{GetCert: getCert}
 	uniqueConfigurations := map[string]*Config{
+		"proxy":    {Proxy: func(request *http.Request) (*url.URL, error) { return nil, nil }},
 		"no tls":   {},
 		"dialer":   {Dial: dialer.DialContext},
 		"dialer2":  {Dial: func(ctx context.Context, network, address string) (net.Conn, error) { return nil, nil }},
+		"dialer3":  {Dial: dialer.DialContext, DialHolder: &DialHolder{Dial: dialer.DialContext}},
+		"dialer4":  {Dial: func(ctx context.Context, network, address string) (net.Conn, error) { return nil, nil }, DialHolder: &DialHolder{Dial: func(ctx context.Context, network, address string) (net.Conn, error) { return nil, nil }}},
 		"insecure": {TLS: TLSConfig{Insecure: true}},
 		"cadata 1": {TLS: TLSConfig{CAData: []byte{1}}},
 		"cadata 2": {TLS: TLSConfig{CAData: []byte{2}}},
@@ -128,6 +137,13 @@ func TestTLSConfigKey(t *testing.T) {
 				GetCert: func() (*tls.Certificate, error) { return nil, nil },
 			},
 		},
+		"getCert3": {
+			TLS: TLSConfig{
+				KeyData:       []byte{1},
+				GetCert:       getCert,
+				GetCertHolder: getCertHolder,
+			},
+		},
 		"getCert1, key 2": {
 			TLS: TLSConfig{
 				KeyData: []byte{2},

staging/src/k8s.io/client-go/transport/config.go

@@ -68,7 +68,11 @@ type Config struct {
 	WrapTransport WrapperFunc
 
 	// Dial specifies the dial function for creating unencrypted TCP connections.
+	// If specified, this transport will be non-cacheable unless DialHolder is also set.
 	Dial func(ctx context.Context, network, address string) (net.Conn, error)
+	// DialHolder can be populated to make transport configs cacheable.
+	// If specified, DialHolder.Dial must be equal to Dial.
+	DialHolder *DialHolder
 
 	// Proxy is the proxy func to be used for all requests made by this
 	// transport. If Proxy is nil, http.ProxyFromEnvironment is used. If Proxy
@@ -78,6 +82,11 @@ type Config struct {
 	Proxy func(*http.Request) (*url.URL, error)
 }
 
+// DialHolder is used to make the wrapped function comparable so that it can be used as a map key.
+type DialHolder struct {
+	Dial func(ctx context.Context, network, address string) (net.Conn, error)
+}
+
 // ImpersonationConfig has all the available impersonation options
 type ImpersonationConfig struct {
 	// UserName matches user.Info.GetName()
@@ -143,5 +152,15 @@ type TLSConfig struct {
 	// To use only http/1.1, set to ["http/1.1"].
 	NextProtos []string
 
-	GetCert func() (*tls.Certificate, error) // Callback that returns a TLS client certificate. CertData, CertFile, KeyData and KeyFile supercede this field.
+	// Callback that returns a TLS client certificate. CertData, CertFile, KeyData and KeyFile supercede this field.
+	// If specified, this transport is non-cacheable unless CertHolder is populated.
+	GetCert func() (*tls.Certificate, error)
+	// CertHolder can be populated to make transport configs that set GetCert cacheable.
+	// If set, CertHolder.GetCert must be equal to GetCert.
+	GetCertHolder *GetCertHolder
+}
+
+// GetCertHolder is used to make the wrapped function comparable so that it can be used as a map key.
+type GetCertHolder struct {
+	GetCert func() (*tls.Certificate, error)
 }

staging/src/k8s.io/client-go/transport/transport.go

@@ -24,6 +24,7 @@ import (
 	"fmt"
 	"net/http"
 	"os"
+	"reflect"
 	"sync"
 	"time"
 
@@ -39,6 +40,10 @@ func New(config *Config) (http.RoundTripper, error) {
 		return nil, fmt.Errorf("using a custom transport with TLS certificate options or the insecure flag is not allowed")
 	}
 
+	if !isValidHolders(config) {
+		return nil, fmt.Errorf("misconfigured holder for dialer or cert callback")
+	}
+
 	var (
 		rt  http.RoundTripper
 		err error
@@ -56,6 +61,26 @@ func New(config *Config) (http.RoundTripper, error) {
 	return HTTPWrappersForConfig(config, rt)
 }
 
+func isValidHolders(config *Config) bool {
+	if config.TLS.GetCertHolder != nil {
+		if config.TLS.GetCertHolder.GetCert == nil ||
+			config.TLS.GetCert == nil ||
+			reflect.ValueOf(config.TLS.GetCertHolder.GetCert).Pointer() != reflect.ValueOf(config.TLS.GetCert).Pointer() {
+			return false
+		}
+	}
+
+	if config.DialHolder != nil {
+		if config.DialHolder.Dial == nil ||
+			config.Dial == nil ||
+			reflect.ValueOf(config.DialHolder.Dial).Pointer() != reflect.ValueOf(config.Dial).Pointer() {
+			return false
+		}
+	}
+
+	return true
+}
+
 // TLSConfigFor returns a tls.Config that will provide the transport level security defined
 // by the provided Config. Will return nil if no transport level security is requested.
 func TLSConfigFor(c *Config) (*tls.Config, error) {

staging/src/k8s.io/client-go/transport/transport_test.go

@@ -21,6 +21,7 @@ import (
 	"crypto/tls"
 	"errors"
 	"fmt"
+	"net"
 	"net/http"
 	"testing"
 )
@@ -94,6 +95,13 @@ stR0Yiw0buV6DL/moUO0HIM9Bjh96HJp+LxiIS6UCdIhMPp5HoQa
 )
 
 func TestNew(t *testing.T) {
+	globalGetCert := &GetCertHolder{
+		GetCert: func() (*tls.Certificate, error) { return nil, nil },
+	}
+	globalDial := &DialHolder{
+		Dial: func(ctx context.Context, network, address string) (net.Conn, error) { return nil, nil },
+	}
+
 	testCases := map[string]struct {
 		Config       *Config
 		Err          bool
@@ -255,6 +263,144 @@ func TestNew(t *testing.T) {
 				},
 			},
 		},
+		"nil holders and nil regular": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert:       nil,
+					GetCertHolder: nil,
+				},
+				Dial:       nil,
+				DialHolder: nil,
+			},
+			Err:          false,
+			TLS:          false,
+			TLSCert:      false,
+			TLSErr:       false,
+			Default:      true,
+			Insecure:     false,
+			DefaultRoots: false,
+		},
+		"nil holders and non-nil regular get cert": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert:       func() (*tls.Certificate, error) { return nil, nil },
+					GetCertHolder: nil,
+				},
+				Dial:       nil,
+				DialHolder: nil,
+			},
+			Err:          false,
+			TLS:          true,
+			TLSCert:      true,
+			TLSErr:       false,
+			Default:      false,
+			Insecure:     false,
+			DefaultRoots: true,
+		},
+		"nil holders and non-nil regular dial": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert:       nil,
+					GetCertHolder: nil,
+				},
+				Dial:       func(ctx context.Context, network, address string) (net.Conn, error) { return nil, nil },
+				DialHolder: nil,
+			},
+			Err:          false,
+			TLS:          true,
+			TLSCert:      false,
+			TLSErr:       false,
+			Default:      false,
+			Insecure:     false,
+			DefaultRoots: true,
+		},
+		"non-nil dial holder and nil regular": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert:       nil,
+					GetCertHolder: nil,
+				},
+				Dial:       nil,
+				DialHolder: &DialHolder{},
+			},
+			Err: true,
+		},
+		"non-nil cert holder and nil regular": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert:       nil,
+					GetCertHolder: &GetCertHolder{},
+				},
+				Dial:       nil,
+				DialHolder: nil,
+			},
+			Err: true,
+		},
+		"non-nil dial holder and non-nil regular": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert:       nil,
+					GetCertHolder: nil,
+				},
+				Dial:       func(ctx context.Context, network, address string) (net.Conn, error) { return nil, nil },
+				DialHolder: &DialHolder{},
+			},
+			Err: true,
+		},
+		"non-nil cert holder and non-nil regular": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert:       func() (*tls.Certificate, error) { return nil, nil },
+					GetCertHolder: &GetCertHolder{},
+				},
+				Dial:       nil,
+				DialHolder: nil,
+			},
+			Err: true,
+		},
+		"non-nil dial holder+internal and non-nil regular": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert:       nil,
+					GetCertHolder: nil,
+				},
+				Dial: func(ctx context.Context, network, address string) (net.Conn, error) { return nil, nil },
+				DialHolder: &DialHolder{
+					Dial: func(ctx context.Context, network, address string) (net.Conn, error) { return nil, nil },
+				},
+			},
+			Err: true,
+		},
+		"non-nil cert holder+internal and non-nil regular": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert: func() (*tls.Certificate, error) { return nil, nil },
+					GetCertHolder: &GetCertHolder{
+						GetCert: func() (*tls.Certificate, error) { return nil, nil },
+					},
+				},
+				Dial:       nil,
+				DialHolder: nil,
+			},
+			Err: true,
+		},
+		"non-nil holders+internal and non-nil regular with correct address": {
+			Config: &Config{
+				TLS: TLSConfig{
+					GetCert:       globalGetCert.GetCert,
+					GetCertHolder: globalGetCert,
+				},
+				Dial:       globalDial.Dial,
+				DialHolder: globalDial,
+			},
+			Err:          false,
+			TLS:          true,
+			TLSCert:      true,
+			TLSErr:       false,
+			Default:      false,
+			Insecure:     false,
+			DefaultRoots: true,
+		},
 	}
 	for k, testCase := range testCases {
 		t.Run(k, func(t *testing.T) {