Switch to a slimmer distroless base image.

At a high level, it switches us to a distroless base container image, but that also includes several related bits: - Add a writable /tmp but make the rest of our filesystems read-only at runtime. - Condense our main server binaries into a single pinniped-server binary. This saves a bunch of space in the image due to duplicated library code. The correct behavior is dispatched based on `os.Args[0]`, and the `pinniped-server` binary is symlinked to `pinniped-concierge` and `pinniped-supervisor`. - Strip debug symbols from our binaries. These aren't really useful in a distroless image anyway and all the normal stuff you'd expect to work, such as stack traces, still does. - Add a separate `pinniped-concierge-kube-cert-agent` binary with "sleep" and "print" functionality instead of using builtin /bin/sleep and /bin/cat for the kube-cert-agent. This is split from the main server binary because the loading/init time of the main server binary was too large for the tiny resource footprint we established in our kube-cert-agent PodSpec. Using a separate binary eliminates this issue and the extra binary adds only around 1.5MiB of image size. - Switch the kube-cert-agent code to use a JSON `{"tls.crt": "<b64 cert>", "tls.key": "<b64 key>"}` format. This is more robust to unexpected input formatting than the old code, which simply concatenated the files with some extra newlines and split on whitespace. - Update integration tests that made now-invalid assumptions about the `pinniped-server` image. Signed-off-by: Matt Moyer <moyerm@vmware.com>
2026-09-26 01:44:17 +00:00 · 2021-08-09 15:05:13 -04:00
parent a464c81711
commit 58bbffded4
19 changed files with 538 additions and 105 deletions
@@ -0,0 +1,390 @@
+// Copyright 2020-2021 the Pinniped contributors. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+// Package localuserauthenticator provides a authentication webhook program.
+//
+// This webhook is meant to be used in demo settings to play around with
+// Pinniped. As well, it can come in handy in integration tests.
+//
+// This webhook is NOT meant for use in production systems.
+package localuserauthenticator
+
+import (
+	"bytes"
+	"context"
+	"crypto/tls"
+	"encoding/csv"
+	"encoding/json"
+	"fmt"
+	"mime"
+	"net"
+	"net/http"
+	"os"
+	"os/signal"
+	"strings"
+	"time"
+
+	"golang.org/x/crypto/bcrypt"
+	authenticationv1beta1 "k8s.io/api/authentication/v1beta1"
+	k8serrors "k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	kubeinformers "k8s.io/client-go/informers"
+	corev1informers "k8s.io/client-go/informers/core/v1"
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/klog/v2"
+
+	"go.pinniped.dev/internal/constable"
+	"go.pinniped.dev/internal/controller/apicerts"
+	"go.pinniped.dev/internal/controllerlib"
+	"go.pinniped.dev/internal/dynamiccert"
+	"go.pinniped.dev/internal/kubeclient"
+	"go.pinniped.dev/internal/plog"
+)
+
+const (
+	// This string must match the name of the Namespace declared in the deployment yaml.
+	namespace = "local-user-authenticator"
+	// This string must match the name of the Service declared in the deployment yaml.
+	serviceName = "local-user-authenticator"
+
+	singletonWorker       = 1
+	defaultResyncInterval = 3 * time.Minute
+
+	invalidRequest = constable.Error("invalid request")
+)
+
+type webhook struct {
+	certProvider   dynamiccert.Private
+	secretInformer corev1informers.SecretInformer
+}
+
+func newWebhook(
+	certProvider dynamiccert.Private,
+	secretInformer corev1informers.SecretInformer,
+) *webhook {
+	return &webhook{
+		certProvider:   certProvider,
+		secretInformer: secretInformer,
+	}
+}
+
+// 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 {
+	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
+			},
+		},
+	}
+
+	errCh := make(chan error)
+	go func() {
+		// Per ListenAndServeTLS doc, the {cert,key}File parameters can be empty
+		// since we want to use the certs from http.Server.TLSConfig.
+		errCh <- server.ServeTLS(l, "", "")
+	}()
+
+	go func() {
+		select {
+		case err := <-errCh:
+			plog.Debug("server exited", "err", err)
+		case <-ctx.Done():
+			plog.Debug("server context cancelled", "err", ctx.Err())
+			if err := server.Shutdown(context.Background()); err != nil {
+				plog.Debug("server shutdown failed", "err", err)
+			}
+		}
+	}()
+
+	return nil
+}
+
+func (w *webhook) ServeHTTP(rsp http.ResponseWriter, req *http.Request) {
+	username, password, err := getUsernameAndPasswordFromRequest(rsp, req)
+	if err != nil {
+		return
+	}
+	defer func() { _ = req.Body.Close() }()
+
+	secret, err := w.secretInformer.Lister().Secrets(namespace).Get(username)
+	notFound := k8serrors.IsNotFound(err)
+	if err != nil && !notFound {
+		plog.Debug("could not get secret", "err", err)
+		rsp.WriteHeader(http.StatusInternalServerError)
+		return
+	}
+
+	if notFound {
+		plog.Debug("user not found")
+		respondWithUnauthenticated(rsp)
+		return
+	}
+
+	passwordMatches := bcrypt.CompareHashAndPassword(
+		secret.Data["passwordHash"],
+		[]byte(password),
+	) == nil
+	if !passwordMatches {
+		plog.Debug("authentication failed: wrong password")
+		respondWithUnauthenticated(rsp)
+		return
+	}
+
+	groups := []string{}
+	groupsBuf := bytes.NewBuffer(secret.Data["groups"])
+	if groupsBuf.Len() > 0 {
+		groupsCSVReader := csv.NewReader(groupsBuf)
+		groups, err = groupsCSVReader.Read()
+		if err != nil {
+			plog.Debug("could not read groups", "err", err)
+			rsp.WriteHeader(http.StatusInternalServerError)
+			return
+		}
+		trimLeadingAndTrailingWhitespace(groups)
+	}
+
+	plog.Debug("successful authentication")
+	respondWithAuthenticated(rsp, secret.ObjectMeta.Name, groups)
+}
+
+func getUsernameAndPasswordFromRequest(rsp http.ResponseWriter, req *http.Request) (string, string, error) {
+	if req.URL.Path != "/authenticate" {
+		plog.Debug("received request path other than /authenticate", "path", req.URL.Path)
+		rsp.WriteHeader(http.StatusNotFound)
+		return "", "", invalidRequest
+	}
+
+	if req.Method != http.MethodPost {
+		plog.Debug("received request method other than post", "method", req.Method)
+		rsp.WriteHeader(http.StatusMethodNotAllowed)
+		return "", "", invalidRequest
+	}
+
+	if !headerContains(req, "Content-Type", "application/json") {
+		plog.Debug("content type is not application/json", "Content-Type", req.Header.Values("Content-Type"))
+		rsp.WriteHeader(http.StatusUnsupportedMediaType)
+		return "", "", invalidRequest
+	}
+
+	if !headerContains(req, "Accept", "application/json") &&
+		!headerContains(req, "Accept", "application/*") &&
+		!headerContains(req, "Accept", "*/*") {
+		plog.Debug("client does not accept application/json", "Accept", req.Header.Values("Accept"))
+		rsp.WriteHeader(http.StatusUnsupportedMediaType)
+		return "", "", invalidRequest
+	}
+
+	if req.Body == nil {
+		plog.Debug("invalid nil body")
+		rsp.WriteHeader(http.StatusBadRequest)
+		return "", "", invalidRequest
+	}
+
+	var body authenticationv1beta1.TokenReview
+	if err := json.NewDecoder(req.Body).Decode(&body); err != nil {
+		plog.Debug("failed to decode body", "err", err)
+		rsp.WriteHeader(http.StatusBadRequest)
+		return "", "", invalidRequest
+	}
+
+	if body.APIVersion != authenticationv1beta1.SchemeGroupVersion.String() {
+		plog.Debug("invalid TokenReview apiVersion", "apiVersion", body.APIVersion)
+		rsp.WriteHeader(http.StatusBadRequest)
+		return "", "", invalidRequest
+	}
+
+	if body.Kind != "TokenReview" {
+		plog.Debug("invalid TokenReview kind", "kind", body.Kind)
+		rsp.WriteHeader(http.StatusBadRequest)
+		return "", "", invalidRequest
+	}
+
+	tokenSegments := strings.SplitN(body.Spec.Token, ":", 2)
+	if len(tokenSegments) != 2 {
+		plog.Debug("bad token format in request")
+		rsp.WriteHeader(http.StatusBadRequest)
+		return "", "", invalidRequest
+	}
+
+	return tokenSegments[0], tokenSegments[1], nil
+}
+
+func headerContains(req *http.Request, headerName, s string) bool {
+	headerValues := req.Header.Values(headerName)
+	for i := range headerValues {
+		mimeTypes := strings.Split(headerValues[i], ",")
+		for _, mimeType := range mimeTypes {
+			mediaType, _, _ := mime.ParseMediaType(mimeType)
+			if mediaType == s {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+func trimLeadingAndTrailingWhitespace(ss []string) {
+	for i := range ss {
+		ss[i] = strings.TrimSpace(ss[i])
+	}
+}
+
+func respondWithUnauthenticated(rsp http.ResponseWriter) {
+	rsp.Header().Add("Content-Type", "application/json")
+
+	body := authenticationv1beta1.TokenReview{
+		TypeMeta: metav1.TypeMeta{
+			Kind:       "TokenReview",
+			APIVersion: authenticationv1beta1.SchemeGroupVersion.String(),
+		},
+		Status: authenticationv1beta1.TokenReviewStatus{
+			Authenticated: false,
+		},
+	}
+	if err := json.NewEncoder(rsp).Encode(body); err != nil {
+		plog.Debug("could not encode response", "err", err)
+		rsp.WriteHeader(http.StatusInternalServerError)
+	}
+}
+
+func respondWithAuthenticated(
+	rsp http.ResponseWriter,
+	username string,
+	groups []string,
+) {
+	rsp.Header().Add("Content-Type", "application/json")
+	body := authenticationv1beta1.TokenReview{
+		TypeMeta: metav1.TypeMeta{
+			Kind:       "TokenReview",
+			APIVersion: authenticationv1beta1.SchemeGroupVersion.String(),
+		},
+		Status: authenticationv1beta1.TokenReviewStatus{
+			Authenticated: true,
+			User: authenticationv1beta1.UserInfo{
+				Username: username,
+				Groups:   groups,
+			},
+		},
+	}
+	if err := json.NewEncoder(rsp).Encode(body); err != nil {
+		plog.Debug("could not encode response", "err", err)
+		rsp.WriteHeader(http.StatusInternalServerError)
+	}
+}
+
+func startControllers(
+	ctx context.Context,
+	dynamicCertProvider dynamiccert.Private,
+	kubeClient kubernetes.Interface,
+	kubeInformers kubeinformers.SharedInformerFactory,
+) {
+	aVeryLongTime := time.Hour * 24 * 365 * 100
+
+	const certsSecretResourceName = "local-user-authenticator-tls-serving-certificate"
+
+	// Create controller manager.
+	controllerManager := controllerlib.
+		NewManager().
+		WithController(
+			apicerts.NewCertsManagerController(
+				namespace,
+				certsSecretResourceName,
+				map[string]string{
+					"app": "local-user-authenticator",
+				},
+				kubeClient,
+				kubeInformers.Core().V1().Secrets(),
+				controllerlib.WithInformer,
+				controllerlib.WithInitialEvent,
+				aVeryLongTime,
+				"local-user-authenticator CA",
+				serviceName,
+			),
+			singletonWorker,
+		).
+		WithController(
+			apicerts.NewCertsObserverController(
+				namespace,
+				certsSecretResourceName,
+				dynamicCertProvider,
+				kubeInformers.Core().V1().Secrets(),
+				controllerlib.WithInformer,
+			),
+			singletonWorker,
+		)
+
+	kubeInformers.Start(ctx.Done())
+
+	go controllerManager.Start(ctx)
+}
+
+func startWebhook(
+	ctx context.Context,
+	l net.Listener,
+	dynamicCertProvider dynamiccert.Private,
+	secretInformer corev1informers.SecretInformer,
+) error {
+	return newWebhook(dynamicCertProvider, secretInformer).start(ctx, l)
+}
+
+func waitForSignal() os.Signal {
+	signalCh := make(chan os.Signal, 1)
+	signal.Notify(signalCh, os.Interrupt)
+	return <-signalCh
+}
+
+func run() error {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	client, err := kubeclient.New()
+	if err != nil {
+		return fmt.Errorf("cannot create k8s client: %w", err)
+	}
+
+	kubeInformers := kubeinformers.NewSharedInformerFactoryWithOptions(
+		client.Kubernetes,
+		defaultResyncInterval,
+		kubeinformers.WithNamespace(namespace),
+	)
+
+	dynamicCertProvider := dynamiccert.NewServingCert("local-user-authenticator-tls-serving-certificate")
+
+	startControllers(ctx, dynamicCertProvider, client.Kubernetes, kubeInformers)
+	plog.Debug("controllers are ready")
+
+	//nolint: gosec // Intentionally binding to all network interfaces.
+	l, err := net.Listen("tcp", ":8443")
+	if err != nil {
+		return fmt.Errorf("cannot create listener: %w", err)
+	}
+	defer func() { _ = l.Close() }()
+
+	err = startWebhook(ctx, l, dynamicCertProvider, kubeInformers.Core().V1().Secrets())
+	if err != nil {
+		return fmt.Errorf("cannot start webhook: %w", err)
+	}
+	plog.Debug("webhook is ready", "address", l.Addr().String())
+
+	gotSignal := waitForSignal()
+	plog.Debug("webhook exiting", "signal", gotSignal)
+
+	return nil
+}
+
+func Main() {
+	// Hardcode the logging level to debug, since this is a test app and it is very helpful to have
+	// verbose logs to debug test failures.
+	if err := plog.ValidateAndSetLogLevelGlobally(plog.LevelDebug); err != nil {
+		klog.Fatal(err)
+	}
+	if err := run(); err != nil {
+		klog.Fatal(err)
+	}
+}