use constant time comparison (#3452)

pkg/auth/token.go

@@ -73,30 +73,30 @@ func (auth *TokenAuthSetterVerifier) SetNewWorkConn(newWorkConnMsg *msg.NewWorkC
 	return nil
 }
 
-func (auth *TokenAuthSetterVerifier) VerifyLogin(loginMsg *msg.Login) error {
-	if util.GetAuthKey(auth.token, loginMsg.Timestamp) != loginMsg.PrivilegeKey {
+func (auth *TokenAuthSetterVerifier) VerifyLogin(m *msg.Login) error {
+	if !util.ConstantTimeEqString(util.GetAuthKey(auth.token, m.Timestamp), m.PrivilegeKey) {
 		return fmt.Errorf("token in login doesn't match token from configuration")
 	}
 	return nil
 }
 
-func (auth *TokenAuthSetterVerifier) VerifyPing(pingMsg *msg.Ping) error {
+func (auth *TokenAuthSetterVerifier) VerifyPing(m *msg.Ping) error {
 	if !auth.AuthenticateHeartBeats {
 		return nil
 	}
 
-	if util.GetAuthKey(auth.token, pingMsg.Timestamp) != pingMsg.PrivilegeKey {
+	if !util.ConstantTimeEqString(util.GetAuthKey(auth.token, m.Timestamp), m.PrivilegeKey) {
 		return fmt.Errorf("token in heartbeat doesn't match token from configuration")
 	}
 	return nil
 }
 
-func (auth *TokenAuthSetterVerifier) VerifyNewWorkConn(newWorkConnMsg *msg.NewWorkConn) error {
+func (auth *TokenAuthSetterVerifier) VerifyNewWorkConn(m *msg.NewWorkConn) error {
 	if !auth.AuthenticateNewWorkConns {
 		return nil
 	}
 
-	if util.GetAuthKey(auth.token, newWorkConnMsg.Timestamp) != newWorkConnMsg.PrivilegeKey {
+	if !util.ConstantTimeEqString(util.GetAuthKey(auth.token, m.Timestamp), m.PrivilegeKey) {
 		return fmt.Errorf("token in NewWorkConn doesn't match token from configuration")
 	}
 	return nil

pkg/nathole/controller.go

@@ -174,7 +174,7 @@ func (c *Controller) HandleVisitor(m *msg.NatHoleVisitor, transporter transport.
 		if !ok {
 			return fmt.Errorf("xtcp server for [%s] doesn't exist", m.ProxyName)
 		}
-		if m.SignKey != util.GetAuthKey(clientCfg.sk, m.Timestamp) {
+		if !util.ConstantTimeEqString(m.SignKey, util.GetAuthKey(clientCfg.sk, m.Timestamp)) {
 			return fmt.Errorf("xtcp connection of [%s] auth failed", m.ProxyName)
 		}
 		c.sessions[sid] = session

pkg/plugin/client/http_proxy.go

@@ -21,11 +21,13 @@ import (
 	"net"
 	"net/http"
 	"strings"
+	"time"
 
 	frpIo "github.com/fatedier/golib/io"
 	gnet "github.com/fatedier/golib/net"
 
 	frpNet "github.com/fatedier/frp/pkg/util/net"
+	"github.com/fatedier/frp/pkg/util/util"
 )
 
 const PluginHTTPProxy = "http_proxy"
@@ -179,7 +181,9 @@ func (hp *HTTPProxy) Auth(req *http.Request) bool {
 		return false
 	}
 
-	if pair[0] != hp.AuthUser || pair[1] != hp.AuthPasswd {
+	if !util.ConstantTimeEqString(pair[0], hp.AuthUser) ||
+		!util.ConstantTimeEqString(pair[1], hp.AuthPasswd) {
+		time.Sleep(200 * time.Millisecond)
 		return false
 	}
 	return true

pkg/plugin/client/static_file.go

@@ -18,6 +18,7 @@ import (
 	"io"
 	"net"
 	"net/http"
+	"time"
 
 	"github.com/gorilla/mux"
 
@@ -64,7 +65,7 @@ func NewStaticFilePlugin(params map[string]string) (Plugin, error) {
 	}
 
 	router := mux.NewRouter()
-	router.Use(frpNet.NewHTTPAuthMiddleware(httpUser, httpPasswd).Middleware)
+	router.Use(frpNet.NewHTTPAuthMiddleware(httpUser, httpPasswd).SetAuthFailDelay(200 * time.Millisecond).Middleware)
 	router.PathPrefix(prefix).Handler(frpNet.MakeHTTPGzipHandler(http.StripPrefix(prefix, http.FileServer(http.Dir(localPath))))).Methods("GET")
 	sp.s = &http.Server{
 		Handler: router,

pkg/util/net/http.go

@@ -19,6 +19,9 @@ import (
 	"io"
 	"net/http"
 	"strings"
+	"time"
+
+	"github.com/fatedier/frp/pkg/util/util"
 )
 
 type HTTPAuthWraper struct {
@@ -46,8 +49,9 @@ func (aw *HTTPAuthWraper) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 }
 
 type HTTPAuthMiddleware struct {
-	user   string
-	passwd string
+	user          string
+	passwd        string
+	authFailDelay time.Duration
 }
 
 func NewHTTPAuthMiddleware(user, passwd string) *HTTPAuthMiddleware {
@@ -57,32 +61,28 @@ func NewHTTPAuthMiddleware(user, passwd string) *HTTPAuthMiddleware {
 	}
 }
 
+func (authMid *HTTPAuthMiddleware) SetAuthFailDelay(delay time.Duration) *HTTPAuthMiddleware {
+	authMid.authFailDelay = delay
+	return authMid
+}
+
 func (authMid *HTTPAuthMiddleware) Middleware(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		reqUser, reqPasswd, hasAuth := r.BasicAuth()
 		if (authMid.user == "" && authMid.passwd == "") ||
-			(hasAuth && reqUser == authMid.user && reqPasswd == authMid.passwd) {
+			(hasAuth && util.ConstantTimeEqString(reqUser, authMid.user) &&
+				util.ConstantTimeEqString(reqPasswd, authMid.passwd)) {
 			next.ServeHTTP(w, r)
 		} else {
+			if authMid.authFailDelay > 0 {
+				time.Sleep(authMid.authFailDelay)
+			}
 			w.Header().Set("WWW-Authenticate", `Basic realm="Restricted"`)
 			http.Error(w, http.StatusText(http.StatusUnauthorized), http.StatusUnauthorized)
 		}
 	})
 }
 
-func HTTPBasicAuth(h http.HandlerFunc, user, passwd string) http.HandlerFunc {
-	return func(w http.ResponseWriter, r *http.Request) {
-		reqUser, reqPasswd, hasAuth := r.BasicAuth()
-		if (user == "" && passwd == "") ||
-			(hasAuth && reqUser == user && reqPasswd == passwd) {
-			h.ServeHTTP(w, r)
-		} else {
-			w.Header().Set("WWW-Authenticate", `Basic realm="Restricted"`)
-			http.Error(w, http.StatusText(http.StatusUnauthorized), http.StatusUnauthorized)
-		}
-	}
-}
-
 type HTTPGzipWraper struct {
 	h http.Handler
 }

pkg/util/util/util.go

@@ -17,6 +17,7 @@ package util
 import (
 	"crypto/md5"
 	"crypto/rand"
+	"crypto/subtle"
 	"encoding/hex"
 	"fmt"
 	mathrand "math/rand"
@@ -139,3 +140,7 @@ func RandomSleep(duration time.Duration, minRatio, maxRatio float64) time.Durati
 	time.Sleep(d)
 	return d
 }
+
+func ConstantTimeEqString(a, b string) bool {
+	return subtle.ConstantTimeCompare([]byte(a), []byte(b)) == 1
+}