Expose the constants in pkg/controller/bootstrap and add a validate token function

pkg/bootstrap/api/types.go

@@ -45,4 +45,13 @@ const (
 	// sign configs as part of the bootstrap process. Value must be "true". Any
 	// other value is assumed to be false. Optional.
 	BootstrapTokenUsageSigningKey = "usage-bootstrap-signing"
+
+	// ConfigMapClusterInfo defines the name for the ConfigMap where the information how to connect and trust the cluster exist
+	ConfigMapClusterInfo = "cluster-info"
+
+	// KubeConfigKey defines at which key in the Data object of the ConfigMap the KubeConfig object is stored
+	KubeConfigKey = "kubeconfig"
+
+	// JWSSignatureKeyPrefix defines what key prefix the JWS-signed tokens have
+	JWSSignatureKeyPrefix = "jws-kubeconfig-"
 )

pkg/controller/bootstrap/bootstrapsigner.go

@@ -38,12 +38,6 @@ import (
 	"k8s.io/kubernetes/pkg/util/metrics"
 )
 
-const (
-	configMapClusterInfo = "cluster-info"
-	kubeConfigKey        = "kubeconfig"
-	signaturePrefix      = "jws-kubeconfig-"
-)
-
 // BootstrapSignerOptions contains options for the BootstrapSigner
 type BootstrapSignerOptions struct {
 
@@ -70,7 +64,7 @@ type BootstrapSignerOptions struct {
 func DefaultBootstrapSignerOptions() BootstrapSignerOptions {
 	return BootstrapSignerOptions{
 		ConfigMapNamespace:   api.NamespacePublic,
-		ConfigMapName:        configMapClusterInfo,
+		ConfigMapName:        bootstrapapi.ConfigMapClusterInfo,
 		TokenSecretNamespace: api.NamespaceSystem,
 	}
 }
@@ -191,17 +185,17 @@ func (e *BootstrapSigner) signConfigMap() {
 	}
 
 	// First capture the config we are signing
-	content, ok := newCM.Data[kubeConfigKey]
+	content, ok := newCM.Data[bootstrapapi.KubeConfigKey]
 	if !ok {
-		glog.V(3).Infof("No %s key in %s/%s ConfigMap", kubeConfigKey, origCM.Namespace, origCM.Name)
+		glog.V(3).Infof("No %s key in %s/%s ConfigMap", bootstrapapi.KubeConfigKey, origCM.Namespace, origCM.Name)
 		return
 	}
 
 	// Next remove and save all existing signatures
 	sigs := map[string]string{}
 	for key, value := range newCM.Data {
-		if strings.HasPrefix(key, signaturePrefix) {
-			tokenID := strings.TrimPrefix(key, signaturePrefix)
+		if strings.HasPrefix(key, bootstrapapi.JWSSignatureKeyPrefix) {
+			tokenID := strings.TrimPrefix(key, bootstrapapi.JWSSignatureKeyPrefix)
 			sigs[tokenID] = value
 			delete(newCM.Data, key)
 		}
@@ -222,7 +216,7 @@ func (e *BootstrapSigner) signConfigMap() {
 		}
 		delete(sigs, tokenID)
 
-		newCM.Data[signaturePrefix+tokenID] = sig
+		newCM.Data[bootstrapapi.JWSSignatureKeyPrefix+tokenID] = sig
 	}
 
 	// If we have signatures left over we know that some signatures were

pkg/controller/bootstrap/bootstrapsigner_test.go

@@ -27,6 +27,7 @@ import (
 	"k8s.io/client-go/pkg/api"
 	"k8s.io/client-go/pkg/api/v1"
 	core "k8s.io/client-go/testing"
+	bootstrapapi "k8s.io/kubernetes/pkg/bootstrap/api"
 )
 
 func init() {
@@ -43,15 +44,15 @@ func newConfigMap(tokenID, signature string) *v1.ConfigMap {
 	ret := &v1.ConfigMap{
 		ObjectMeta: metav1.ObjectMeta{
 			Namespace:       metav1.NamespacePublic,
-			Name:            configMapClusterInfo,
+			Name:            bootstrapapi.ConfigMapClusterInfo,
 			ResourceVersion: "1",
 		},
 		Data: map[string]string{
-			kubeConfigKey: "payload",
+			bootstrapapi.KubeConfigKey: "payload",
 		},
 	}
 	if len(tokenID) > 0 {
-		ret.Data[signaturePrefix+tokenID] = signature
+		ret.Data[bootstrapapi.JWSSignatureKeyPrefix+tokenID] = signature
 	}
 	return ret
 }

pkg/controller/bootstrap/jws.go

@@ -34,17 +34,17 @@ func computeDetachedSig(content, tokenID, tokenSecret string) (string, error) {
 
 	signer, err := jose.NewSigner(jose.HS256, jwk)
 	if err != nil {
-		return "", nil
+		return "", fmt.Errorf("can't make a HS256 signer from the given token: %v", err)
 	}
 
 	jws, err := signer.Sign([]byte(content))
 	if err != nil {
-		return "", nil
+		return "", fmt.Errorf("can't HS256-sign the given token: %v", err)
 	}
 
 	fullSig, err := jws.CompactSerialize()
 	if err != nil {
-		return "", nil
+		return "", fmt.Errorf("can't serialize the given token: %v", err)
 	}
 	return stripContent(fullSig)
 }
@@ -57,8 +57,17 @@ func computeDetachedSig(content, tokenID, tokenSecret string) (string, error) {
 func stripContent(fullSig string) (string, error) {
 	parts := strings.Split(fullSig, ".")
 	if len(parts) != 3 {
-		return "", fmt.Errorf("Compact JWS format must have three parts")
+		return "", fmt.Errorf("compact JWS format must have three parts")
 	}
 
 	return parts[0] + ".." + parts[2], nil
 }
+
+// DetachedTokenIsValid checks whether a given detached JWS-encoded token matches JWS output of the given content and token
+func DetachedTokenIsValid(detachedToken, content, tokenID, tokenSecret string) bool {
+	newToken, err := computeDetachedSig(content, tokenID, tokenSecret)
+	if err != nil {
+		return false
+	}
+	return detachedToken == newToken
+}

pkg/controller/bootstrap/jws_test.go

@@ -51,3 +51,17 @@ func TestComputeDetachedSig(t *testing.T) {
 		t.Errorf("Wrong signature. Got: %v", sig)
 	}
 }
+
+func TestDetachedTokenIsValid(t *testing.T) {
+	// Valid detached JWS token and valid inputs should succeed
+	sig := "eyJhbGciOiJIUzI1NiIsImtpZCI6Impvc2h1YSJ9..VShe2taLd-YTrmWuRkcL_8QTNDHYxQIEBsAYYiIj1_8"
+	if !DetachedTokenIsValid(sig, content, id, secret) {
+		t.Errorf("Content %q and token \"%s:%s\" should equal signature: %q", content, id, secret, sig)
+	}
+
+	// Invalid detached JWS token and valid inputs should fail
+	sig2 := sig + "foo"
+	if DetachedTokenIsValid(sig2, content, id, secret) {
+		t.Errorf("Content %q and token \"%s:%s\" should not equal signature: %q", content, id, secret, sig)
+	}
+}