// Check for CSRF token on /rest/ URLs. If a correct one is not given, reject
// the request with 403. For / and /index.html, set a new CSRF cookie if none
// is currently set.
func csrfMiddleware(unique string, prefix string, cfg config.GUIConfiguration, next http.Handler) http.Handler {
loadCsrfTokens()
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
// Allow requests carrying a valid API key
if cfg.IsValidAPIKey(r.Header.Get("X-API-Key")) {
next.ServeHTTP(w, r)
return
}
// Allow requests for the front page, and set a CSRF cookie if there isn't already a valid one.
if !strings.HasPrefix(r.URL.Path, prefix) {
cookie, err := r.Cookie("CSRF-Token-" + unique)
if err != nil || !validCsrfToken(cookie.Value) {
httpl.Debugln("new CSRF cookie in response to request for", r.URL)
cookie = &http.Cookie{
Name: "CSRF-Token-" + unique,
Value: newCsrfToken(),
}
http.SetCookie(w, cookie)
}
next.ServeHTTP(w, r)
return
}
if r.Method == "GET" {
// Allow GET requests unconditionally, but if we got the CSRF
// token cookie do the verification anyway so we keep the
// csrfTokens list sorted by recent usage. We don't care about the
// outcome of the validity check.
if cookie, err := r.Cookie("CSRF-Token-" + unique); err == nil {
validCsrfToken(cookie.Value)
}
next.ServeHTTP(w, r)
return
}
// Verify the CSRF token
token := r.Header.Get("X-CSRF-Token-" + unique)
if !validCsrfToken(token) {
http.Error(w, "CSRF Error", 403)
return
}
next.ServeHTTP(w, r)
})
}
func (s *apiService) getListener(guiCfg config.GUIConfiguration) (net.Listener, error) {
cert, err := tls.LoadX509KeyPair(locations[locHTTPSCertFile], locations[locHTTPSKeyFile])
if err != nil {
l.Infoln("Loading HTTPS certificate:", err)
l.Infoln("Creating new HTTPS certificate")
// When generating the HTTPS certificate, use the system host name per
// default. If that isn't available, use the "syncthing" default.
var name string
name, err = os.Hostname()
if err != nil {
name = tlsDefaultCommonName
}
cert, err = tlsutil.NewCertificate(locations[locHTTPSCertFile], locations[locHTTPSKeyFile], name, httpsRSABits)
}
if err != nil {
return nil, err
}
tlsCfg := &tls.Config{
Certificates: []tls.Certificate{cert},
MinVersion: tls.VersionTLS10, // No SSLv3
CipherSuites: []uint16{
// No RC4
tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
tls.TLS_RSA_WITH_AES_128_CBC_SHA,
tls.TLS_RSA_WITH_AES_256_CBC_SHA,
tls.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA,
tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA,
},
}
rawListener, err := net.Listen("tcp", guiCfg.Address())
if err != nil {
return nil, err
}
listener := &tlsutil.DowngradingListener{rawListener, tlsCfg}
return listener, nil
}
func basicAuthAndSessionMiddleware(cookieName string, cfg config.GUIConfiguration, next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if cfg.IsValidAPIKey(r.Header.Get("X-API-Key")) {
next.ServeHTTP(w, r)
return
}
cookie, err := r.Cookie(cookieName)
if err == nil && cookie != nil {
sessionsMut.Lock()
_, ok := sessions[cookie.Value]
sessionsMut.Unlock()
if ok {
next.ServeHTTP(w, r)
return
}
}
httpl.Debugln("Sessionless HTTP request with authentication; this is expensive.")
error := func() {
time.Sleep(time.Duration(rand.Intn(100)+100) * time.Millisecond)
w.Header().Set("WWW-Authenticate", "Basic realm=\"Authorization Required\"")
http.Error(w, "Not Authorized", http.StatusUnauthorized)
}
hdr := r.Header.Get("Authorization")
if !strings.HasPrefix(hdr, "Basic ") {
error()
return
}
hdr = hdr[6:]
bs, err := base64.StdEncoding.DecodeString(hdr)
if err != nil {
error()
return
}
fields := bytes.SplitN(bs, []byte(":"), 2)
if len(fields) != 2 {
error()
return
}
username := string(fields[0])
if username != cfg.User {
emitLoginAttempt(false, username)
error()
return
}
if err := bcrypt.CompareHashAndPassword([]byte(cfg.Password), fields[1]); err != nil {
emitLoginAttempt(false, username)
error()
return
}
sessionid := randomString(32)
sessionsMut.Lock()
sessions[sessionid] = true
sessionsMut.Unlock()
http.SetCookie(w, &http.Cookie{
Name: cookieName,
Value: sessionid,
MaxAge: 0,
})
emitLoginAttempt(true, username)
next.ServeHTTP(w, r)
})
}
