Force the use of secure TLS config

This change updates the TLS config used by all pinniped components.
There are no configuration knobs associated with this change.  Thus
this change tightens our static defaults.

There are four TLS config levels:

1. Secure (TLS 1.3 only)
2. Default (TLS 1.2+ best ciphers that are well supported)
3. Default LDAP (TLS 1.2+ with less good ciphers)
4. Legacy (currently unused, TLS 1.2+ with all non-broken ciphers)

Highlights per component:

1. pinniped CLI
   - uses "secure" config against KAS
   - uses "default" for all other connections
2. concierge
   - uses "secure" config as an aggregated API server
   - uses "default" config as a impersonation proxy API server
   - uses "secure" config against KAS
   - uses "default" config for JWT authenticater (mostly, see code)
   - no changes to webhook authenticater (see code)
3. supervisor
   - uses "default" config as a server
   - uses "secure" config against KAS
   - uses "default" config against OIDC IDPs
   - uses "default LDAP" config against LDAP IDPs

Signed-off-by: Monis Khan <mok@vmware.com>

internal/localuserauthenticator/localuserauthenticator.go

@@ -36,6 +36,7 @@ import (
 	"go.pinniped.dev/internal/constable"
 	"go.pinniped.dev/internal/controller/apicerts"
 	"go.pinniped.dev/internal/controllerlib"
+	"go.pinniped.dev/internal/crypto/ptls"
 	"go.pinniped.dev/internal/dynamiccert"
 	"go.pinniped.dev/internal/kubeclient"
 	"go.pinniped.dev/internal/plog"
@@ -71,16 +72,15 @@ func newWebhook(
 // start runs the webhook in a separate goroutine and returns whether or not the
 // webhook was started successfully.
 func (w *webhook) start(ctx context.Context, l net.Listener) error {
+	c := ptls.Secure(nil)
+	c.GetCertificate = func(_ *tls.ClientHelloInfo) (*tls.Certificate, error) {
+		certPEM, keyPEM := w.certProvider.CurrentCertKeyContent()
+		cert, err := tls.X509KeyPair(certPEM, keyPEM)
+		return &cert, err
+	}
 	server := http.Server{
-		Handler: w,
-		TLSConfig: &tls.Config{
-			MinVersion: tls.VersionTLS13,
-			GetCertificate: func(_ *tls.ClientHelloInfo) (*tls.Certificate, error) {
-				certPEM, keyPEM := w.certProvider.CurrentCertKeyContent()
-				cert, err := tls.X509KeyPair(certPEM, keyPEM)
-				return &cert, err
-			},
-		},
+		Handler:   w,
+		TLSConfig: c,
 	}
 
 	errCh := make(chan error)

internal/localuserauthenticator/localuserauthenticator_test.go

@@ -6,7 +6,6 @@ package localuserauthenticator
 import (
 	"bytes"
 	"context"
-	"crypto/tls"
 	"crypto/x509"
 	"encoding/json"
 	"fmt"
@@ -25,6 +24,7 @@ import (
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime/schema"
+	utilnet "k8s.io/apimachinery/pkg/util/net"
 	kubeinformers "k8s.io/client-go/informers"
 	corev1informers "k8s.io/client-go/informers/core/v1"
 	"k8s.io/client-go/kubernetes"
@@ -32,6 +32,7 @@ import (
 
 	"go.pinniped.dev/internal/certauthority"
 	"go.pinniped.dev/internal/dynamiccert"
+	"go.pinniped.dev/internal/net/phttp"
 )
 
 func TestWebhook(t *testing.T) {
@@ -102,7 +103,7 @@ func TestWebhook(t *testing.T) {
 	defer func() { _ = l.Close() }()
 	require.NoError(t, w.start(ctx, l))
 
-	client := newClient(caBundle, serverName)
+	client := newClient(t, caBundle, serverName)
 
 	goodURL := fmt.Sprintf("https://%s/authenticate", l.Addr().String())
 	goodRequestHeaders := map[string][]string{
@@ -475,18 +476,20 @@ func newCertProvider(t *testing.T) (dynamiccert.Private, []byte, string) {
 
 // newClient creates an http.Client that can be used to make an HTTPS call to a
 // service whose serving certs can be verified by the provided CA bundle.
-func newClient(caBundle []byte, serverName string) *http.Client {
+func newClient(t *testing.T, caBundle []byte, serverName string) *http.Client {
+	t.Helper()
+
 	rootCAs := x509.NewCertPool()
-	rootCAs.AppendCertsFromPEM(caBundle)
-	return &http.Client{
-		Transport: &http.Transport{
-			TLSClientConfig: &tls.Config{
-				MinVersion: tls.VersionTLS13,
-				RootCAs:    rootCAs,
-				ServerName: serverName,
-			},
-		},
-	}
+	ok := rootCAs.AppendCertsFromPEM(caBundle)
+	require.True(t, ok)
+
+	c := phttp.Secure(rootCAs)
+
+	tlsConfig, err := utilnet.TLSClientConfig(c.Transport)
+	require.NoError(t, err)
+	tlsConfig.ServerName = serverName
+
+	return c
 }
 
 // newTokenReviewBody creates an io.ReadCloser that contains a JSON-encodeed