vendor files

vendor/k8s.io/kubernetes/pkg/serviceaccount/jwt.go

@@ -0,0 +1,250 @@
+/*
+Copyright 2014 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 serviceaccount
+
+import (
+	"bytes"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rsa"
+	"errors"
+	"fmt"
+
+	"k8s.io/api/core/v1"
+	"k8s.io/apiserver/pkg/authentication/authenticator"
+	apiserverserviceaccount "k8s.io/apiserver/pkg/authentication/serviceaccount"
+	"k8s.io/apiserver/pkg/authentication/user"
+
+	jwt "github.com/dgrijalva/jwt-go"
+	"github.com/golang/glog"
+)
+
+const (
+	Issuer = "kubernetes/serviceaccount"
+
+	SubjectClaim            = "sub"
+	IssuerClaim             = "iss"
+	ServiceAccountNameClaim = "kubernetes.io/serviceaccount/service-account.name"
+	ServiceAccountUIDClaim  = "kubernetes.io/serviceaccount/service-account.uid"
+	SecretNameClaim         = "kubernetes.io/serviceaccount/secret.name"
+	NamespaceClaim          = "kubernetes.io/serviceaccount/namespace"
+)
+
+// ServiceAccountTokenGetter defines functions to retrieve a named service account and secret
+type ServiceAccountTokenGetter interface {
+	GetServiceAccount(namespace, name string) (*v1.ServiceAccount, error)
+	GetSecret(namespace, name string) (*v1.Secret, error)
+}
+
+type TokenGenerator interface {
+	// GenerateToken generates a token which will identify the given ServiceAccount.
+	// The returned token will be stored in the given (and yet-unpersisted) Secret.
+	GenerateToken(serviceAccount v1.ServiceAccount, secret v1.Secret) (string, error)
+}
+
+// JWTTokenGenerator returns a TokenGenerator that generates signed JWT tokens, using the given privateKey.
+// privateKey is a PEM-encoded byte array of a private RSA key.
+// JWTTokenAuthenticator()
+func JWTTokenGenerator(privateKey interface{}) TokenGenerator {
+	return &jwtTokenGenerator{privateKey}
+}
+
+type jwtTokenGenerator struct {
+	privateKey interface{}
+}
+
+func (j *jwtTokenGenerator) GenerateToken(serviceAccount v1.ServiceAccount, secret v1.Secret) (string, error) {
+	var method jwt.SigningMethod
+	switch privateKey := j.privateKey.(type) {
+	case *rsa.PrivateKey:
+		method = jwt.SigningMethodRS256
+	case *ecdsa.PrivateKey:
+		switch privateKey.Curve {
+		case elliptic.P256():
+			method = jwt.SigningMethodES256
+		case elliptic.P384():
+			method = jwt.SigningMethodES384
+		case elliptic.P521():
+			method = jwt.SigningMethodES512
+		default:
+			return "", fmt.Errorf("unknown private key curve, must be 256, 384, or 521")
+		}
+	default:
+		return "", fmt.Errorf("unknown private key type %T, must be *rsa.PrivateKey or *ecdsa.PrivateKey", j.privateKey)
+	}
+
+	token := jwt.New(method)
+
+	claims, _ := token.Claims.(jwt.MapClaims)
+
+	// Identify the issuer
+	claims[IssuerClaim] = Issuer
+
+	// Username
+	claims[SubjectClaim] = apiserverserviceaccount.MakeUsername(serviceAccount.Namespace, serviceAccount.Name)
+
+	// Persist enough structured info for the authenticator to be able to look up the service account and secret
+	claims[NamespaceClaim] = serviceAccount.Namespace
+	claims[ServiceAccountNameClaim] = serviceAccount.Name
+	claims[ServiceAccountUIDClaim] = serviceAccount.UID
+	claims[SecretNameClaim] = secret.Name
+
+	// Sign and get the complete encoded token as a string
+	return token.SignedString(j.privateKey)
+}
+
+// JWTTokenAuthenticator authenticates tokens as JWT tokens produced by JWTTokenGenerator
+// Token signatures are verified using each of the given public keys until one works (allowing key rotation)
+// If lookup is true, the service account and secret referenced as claims inside the token are retrieved and verified with the provided ServiceAccountTokenGetter
+func JWTTokenAuthenticator(keys []interface{}, lookup bool, getter ServiceAccountTokenGetter) authenticator.Token {
+	return &jwtTokenAuthenticator{keys, lookup, getter}
+}
+
+type jwtTokenAuthenticator struct {
+	keys   []interface{}
+	lookup bool
+	getter ServiceAccountTokenGetter
+}
+
+var errMismatchedSigningMethod = errors.New("invalid signing method")
+
+func (j *jwtTokenAuthenticator) AuthenticateToken(token string) (user.Info, bool, error) {
+	var validationError error
+
+	for i, key := range j.keys {
+		// Attempt to verify with each key until we find one that works
+		parsedToken, err := jwt.Parse(token, func(token *jwt.Token) (interface{}, error) {
+			switch token.Method.(type) {
+			case *jwt.SigningMethodRSA:
+				if _, ok := key.(*rsa.PublicKey); ok {
+					return key, nil
+				}
+				return nil, errMismatchedSigningMethod
+			case *jwt.SigningMethodECDSA:
+				if _, ok := key.(*ecdsa.PublicKey); ok {
+					return key, nil
+				}
+				return nil, errMismatchedSigningMethod
+			default:
+				return nil, fmt.Errorf("Unexpected signing method: %v", token.Header["alg"])
+			}
+		})
+
+		if err != nil {
+			switch err := err.(type) {
+			case *jwt.ValidationError:
+				if (err.Errors & jwt.ValidationErrorMalformed) != 0 {
+					// Not a JWT, no point in continuing
+					return nil, false, nil
+				}
+
+				if (err.Errors & jwt.ValidationErrorSignatureInvalid) != 0 {
+					// Signature error, perhaps one of the other keys will verify the signature
+					// If not, we want to return this error
+					glog.V(4).Infof("Signature error (key %d): %v", i, err)
+					validationError = err
+					continue
+				}
+
+				// This key doesn't apply to the given signature type
+				// Perhaps one of the other keys will verify the signature
+				// If not, we want to return this error
+				if err.Inner == errMismatchedSigningMethod {
+					glog.V(4).Infof("Mismatched key type (key %d): %v", i, err)
+					validationError = err
+					continue
+				}
+			}
+
+			// Other errors should just return as errors
+			return nil, false, err
+		}
+
+		// If we get here, we have a token with a recognized signature
+
+		claims, _ := parsedToken.Claims.(jwt.MapClaims)
+
+		// Make sure we issued the token
+		iss, _ := claims[IssuerClaim].(string)
+		if iss != Issuer {
+			return nil, false, nil
+		}
+
+		// Make sure the claims we need exist
+		sub, _ := claims[SubjectClaim].(string)
+		if len(sub) == 0 {
+			return nil, false, errors.New("sub claim is missing")
+		}
+		namespace, _ := claims[NamespaceClaim].(string)
+		if len(namespace) == 0 {
+			return nil, false, errors.New("namespace claim is missing")
+		}
+		secretName, _ := claims[SecretNameClaim].(string)
+		if len(namespace) == 0 {
+			return nil, false, errors.New("secretName claim is missing")
+		}
+		serviceAccountName, _ := claims[ServiceAccountNameClaim].(string)
+		if len(serviceAccountName) == 0 {
+			return nil, false, errors.New("serviceAccountName claim is missing")
+		}
+		serviceAccountUID, _ := claims[ServiceAccountUIDClaim].(string)
+		if len(serviceAccountUID) == 0 {
+			return nil, false, errors.New("serviceAccountUID claim is missing")
+		}
+
+		subjectNamespace, subjectName, err := apiserverserviceaccount.SplitUsername(sub)
+		if err != nil || subjectNamespace != namespace || subjectName != serviceAccountName {
+			return nil, false, errors.New("sub claim is invalid")
+		}
+
+		if j.lookup {
+			// Make sure token hasn't been invalidated by deletion of the secret
+			secret, err := j.getter.GetSecret(namespace, secretName)
+			if err != nil {
+				glog.V(4).Infof("Could not retrieve token %s/%s for service account %s/%s: %v", namespace, secretName, namespace, serviceAccountName, err)
+				return nil, false, errors.New("Token has been invalidated")
+			}
+			if secret.DeletionTimestamp != nil {
+				glog.V(4).Infof("Token is deleted and awaiting removal: %s/%s for service account %s/%s", namespace, secretName, namespace, serviceAccountName)
+				return nil, false, errors.New("Token has been invalidated")
+			}
+			if bytes.Compare(secret.Data[v1.ServiceAccountTokenKey], []byte(token)) != 0 {
+				glog.V(4).Infof("Token contents no longer matches %s/%s for service account %s/%s", namespace, secretName, namespace, serviceAccountName)
+				return nil, false, errors.New("Token does not match server's copy")
+			}
+
+			// Make sure service account still exists (name and UID)
+			serviceAccount, err := j.getter.GetServiceAccount(namespace, serviceAccountName)
+			if err != nil {
+				glog.V(4).Infof("Could not retrieve service account %s/%s: %v", namespace, serviceAccountName, err)
+				return nil, false, err
+			}
+			if serviceAccount.DeletionTimestamp != nil {
+				glog.V(4).Infof("Service account has been deleted %s/%s", namespace, serviceAccountName)
+				return nil, false, fmt.Errorf("ServiceAccount %s/%s has been deleted", namespace, serviceAccountName)
+			}
+			if string(serviceAccount.UID) != serviceAccountUID {
+				glog.V(4).Infof("Service account UID no longer matches %s/%s: %q != %q", namespace, serviceAccountName, string(serviceAccount.UID), serviceAccountUID)
+				return nil, false, fmt.Errorf("ServiceAccount UID (%s) does not match claim (%s)", serviceAccount.UID, serviceAccountUID)
+			}
+		}
+
+		return UserInfo(namespace, serviceAccountName, serviceAccountUID), true, nil
+	}
+
+	return nil, false, validationError
+}