Merge pull request #808 from bcmmbaga/main

Add support for refreshing signing keys on expiry

management/cmd/management.go

@@ -80,6 +80,7 @@ var (
 			if err != nil {
 				return fmt.Errorf("failed reading provided config file: %s: %v", mgmtConfig, err)
 			}
+			config.HttpConfig.IdpSignKeyRefreshEnabled = idpSignKeyRefreshEnabled
 
 			tlsEnabled := false
 			if mgmtLetsencryptDomain != "" || (config.HttpConfig.CertFile != "" && config.HttpConfig.CertKey != "") {
@@ -186,6 +187,7 @@ var (
 				config.HttpConfig.AuthIssuer,
 				config.GetAuthAudiences(),
 				config.HttpConfig.AuthKeysLocation,
+				config.HttpConfig.IdpSignKeyRefreshEnabled,
 			)
 			if err != nil {
 				return fmt.Errorf("failed creating JWT validator: %v", err)

management/cmd/root.go

@@ -23,6 +23,7 @@ var (
 	logFile                  string
 	disableMetrics           bool
 	disableSingleAccMode     bool
+	idpSignKeyRefreshEnabled bool
 
 	rootCmd = &cobra.Command{
 		Use:          "netbird-mgmt",
@@ -54,6 +55,7 @@ func init() {
 	mgmtCmd.Flags().StringVar(&certKey, "cert-key", "", "Location of your SSL certificate private key. Can be used when you have an existing certificate and don't want a new certificate be generated automatically. If letsencrypt-domain is specified this property has no effect")
 	mgmtCmd.Flags().BoolVar(&disableMetrics, "disable-anonymous-metrics", false, "disables push of anonymous usage metrics to NetBird")
 	mgmtCmd.Flags().StringVar(&dnsDomain, "dns-domain", defaultSingleAccModeDomain, fmt.Sprintf("Domain used for peer resolution. This is appended to the peer's name, e.g. pi-server. %s. Max lenght is 192 characters to allow appending to a peer name with up to 63 characters.", defaultSingleAccModeDomain))
+	mgmtCmd.Flags().BoolVar(&idpSignKeyRefreshEnabled, "idp-sign-key-refresh-enabled", false, "Enable cache headers evaluation to determine signing key rotation period. This will refresh the signing key upon expiry.")
 	rootCmd.MarkFlagRequired("config") //nolint
 
 	rootCmd.PersistentFlags().StringVar(&logLevel, "log-level", "info", "")

management/server/config.go

@@ -80,6 +80,8 @@ type HttpServerConfig struct {
 	AuthKeysLocation string
 	// OIDCConfigEndpoint is the endpoint of an IDP manager to get OIDC configuration
 	OIDCConfigEndpoint string
+	// IdpSignKeyRefreshEnabled identifies the signing key is currently being rotated or not
+	IdpSignKeyRefreshEnabled bool
 }
 
 // Host represents a Wiretrustee host (e.g. STUN, TURN, Signal)

management/server/grpcserver.go

@@ -52,7 +52,9 @@ func NewServer(config *Config, accountManager AccountManager, peersUpdateManager
 		jwtValidator, err = jwtclaims.NewJWTValidator(
 			config.HttpConfig.AuthIssuer,
 			config.GetAuthAudiences(),
-			config.HttpConfig.AuthKeysLocation)
+			config.HttpConfig.AuthKeysLocation,
+			config.HttpConfig.IdpSignKeyRefreshEnabled,
+		)
 		if err != nil {
 			return nil, status.Errorf(codes.Internal, "unable to create new jwt middleware, err: %v", err)
 		}

management/server/jwtclaims/jwtValidator.go

@@ -12,6 +12,10 @@ import (
 	"fmt"
 	"math/big"
 	"net/http"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
 
 	"github.com/golang-jwt/jwt"
 	log "github.com/sirupsen/logrus"
@@ -46,6 +50,7 @@ type Options struct {
 // Jwks is a collection of JSONWebKey obtained from Config.HttpServerConfig.AuthKeysLocation
 type Jwks struct {
 	Keys          []JSONWebKey `json:"keys"`
+	expiresInTime time.Time
 }
 
 // JSONWebKey is a representation of a Jason Web Key
@@ -64,12 +69,13 @@ type JWTValidator struct {
 }
 
 // NewJWTValidator constructor
-func NewJWTValidator(issuer string, audienceList []string, keysLocation string) (*JWTValidator, error) {
+func NewJWTValidator(issuer string, audienceList []string, keysLocation string, idpSignkeyRefreshEnabled bool) (*JWTValidator, error) {
 	keys, err := getPemKeys(keysLocation)
 	if err != nil {
 		return nil, err
 	}
 
+	var lock sync.Mutex
 	options := Options{
 		ValidationKeyGetter: func(token *jwt.Token) (interface{}, error) {
 			// Verify 'aud' claim
@@ -89,6 +95,23 @@ func NewJWTValidator(issuer string, audienceList []string, keysLocation string)
 				return token, errors.New("invalid issuer")
 			}
 
+			// If keys are rotated, verify the keys prior to token validation
+			if idpSignkeyRefreshEnabled {
+				// If the keys are invalid, retrieve new ones
+				if !keys.stillValid() {
+					lock.Lock()
+					defer lock.Unlock()
+
+					refreshedKeys, err := getPemKeys(keysLocation)
+					if err != nil {
+						log.Debugf("cannot get JSONWebKey: %v, falling back to old keys", err)
+						refreshedKeys = keys
+					}
+
+					keys = refreshedKeys
+				}
+			}
+
 			cert, err := getPemCert(token, keys)
 			if err != nil {
 				return nil, err
@@ -154,6 +177,11 @@ func (m *JWTValidator) ValidateAndParse(token string) (*jwt.Token, error) {
 	return parsedToken, nil
 }
 
+// stillValid returns true if the JSONWebKey still valid and have enough time to be used
+func (jwks *Jwks) stillValid() bool {
+	return jwks.expiresInTime.IsZero() && time.Now().Add(5*time.Second).Before(jwks.expiresInTime)
+}
+
 func getPemKeys(keysLocation string) (*Jwks, error) {
 	resp, err := http.Get(keysLocation)
 	if err != nil {
@@ -167,6 +195,10 @@ func getPemKeys(keysLocation string) (*Jwks, error) {
 		return jwks, err
 	}
 
+	cacheControlHeader := resp.Header.Get("Cache-Control")
+	expiresIn := getMaxAgeFromCacheHeader(cacheControlHeader)
+	jwks.expiresInTime = time.Now().Add(time.Duration(expiresIn) * time.Second)
+
 	return jwks, err
 }
 
@@ -248,3 +280,26 @@ func convertExponentStringToInt(stringExponent string) (int, error) {
 
 	return int(exponent), nil
 }
+
+// getMaxAgeFromCacheHeader extracts max-age directive from the Cache-Control header
+func getMaxAgeFromCacheHeader(cacheControl string) int {
+	// Split into individual directives
+	directives := strings.Split(cacheControl, ",")
+
+	for _, directive := range directives {
+		directive = strings.TrimSpace(directive)
+		if strings.HasPrefix(directive, "max-age=") {
+			// Extract the max-age value
+			maxAgeStr := strings.TrimPrefix(directive, "max-age=")
+			maxAge, err := strconv.Atoi(maxAgeStr)
+			if err != nil {
+				log.Debugf("error parsing max-age: %v", err)
+				return 0
+			}
+
+			return maxAge
+		}
+	}
+
+	return 0
+}