This enables usage of the audit log to e.g. automatically block remote addresses from connecting after repeated login failures.
213 lines
5.8 KiB
Go
213 lines
5.8 KiB
Go
// Copyright (C) 2014 The Syncthing Authors.
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this file,
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// You can obtain one at https://mozilla.org/MPL/2.0/.
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package api
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import (
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"bytes"
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"crypto/tls"
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"encoding/base64"
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"fmt"
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"net"
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"net/http"
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"strings"
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"time"
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ldap "github.com/go-ldap/ldap/v3"
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"github.com/syncthing/syncthing/lib/config"
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"github.com/syncthing/syncthing/lib/events"
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"github.com/syncthing/syncthing/lib/rand"
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"github.com/syncthing/syncthing/lib/sync"
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"golang.org/x/crypto/bcrypt"
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)
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var (
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sessions = make(map[string]bool)
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sessionsMut = sync.NewMutex()
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)
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func emitLoginAttempt(success bool, username, address string, evLogger events.Logger) {
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evLogger.Log(events.LoginAttempt, map[string]interface{}{
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"success": success,
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"username": username,
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"remoteAddress": address,
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})
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}
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func basicAuthAndSessionMiddleware(cookieName string, guiCfg config.GUIConfiguration, ldapCfg config.LDAPConfiguration, next http.Handler, evLogger events.Logger) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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if guiCfg.IsValidAPIKey(r.Header.Get("X-API-Key")) {
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next.ServeHTTP(w, r)
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return
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}
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cookie, err := r.Cookie(cookieName)
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if err == nil && cookie != nil {
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sessionsMut.Lock()
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_, ok := sessions[cookie.Value]
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sessionsMut.Unlock()
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if ok {
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next.ServeHTTP(w, r)
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return
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}
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}
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l.Debugln("Sessionless HTTP request with authentication; this is expensive.")
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error := func() {
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time.Sleep(time.Duration(rand.Intn(100)+100) * time.Millisecond)
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w.Header().Set("WWW-Authenticate", "Basic realm=\"Authorization Required\"")
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http.Error(w, "Not Authorized", http.StatusUnauthorized)
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}
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hdr := r.Header.Get("Authorization")
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if !strings.HasPrefix(hdr, "Basic ") {
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error()
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return
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}
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hdr = hdr[6:]
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bs, err := base64.StdEncoding.DecodeString(hdr)
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if err != nil {
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error()
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return
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}
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fields := bytes.SplitN(bs, []byte(":"), 2)
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if len(fields) != 2 {
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error()
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return
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}
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username := string(fields[0])
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password := string(fields[1])
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authOk := auth(username, password, guiCfg, ldapCfg)
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if !authOk {
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usernameIso := string(iso88591ToUTF8([]byte(username)))
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passwordIso := string(iso88591ToUTF8([]byte(password)))
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authOk = auth(usernameIso, passwordIso, guiCfg, ldapCfg)
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if authOk {
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username = usernameIso
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}
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}
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if !authOk {
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emitLoginAttempt(false, username, r.RemoteAddr, evLogger)
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error()
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return
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}
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sessionid := rand.String(32)
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sessionsMut.Lock()
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sessions[sessionid] = true
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sessionsMut.Unlock()
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http.SetCookie(w, &http.Cookie{
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Name: cookieName,
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Value: sessionid,
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MaxAge: 0,
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})
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emitLoginAttempt(true, username, r.RemoteAddr, evLogger)
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next.ServeHTTP(w, r)
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})
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}
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func auth(username string, password string, guiCfg config.GUIConfiguration, ldapCfg config.LDAPConfiguration) bool {
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if guiCfg.AuthMode == config.AuthModeLDAP {
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return authLDAP(username, password, ldapCfg)
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} else {
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return authStatic(username, password, guiCfg.User, guiCfg.Password)
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}
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}
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func authStatic(username string, password string, configUser string, configPassword string) bool {
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configPasswordBytes := []byte(configPassword)
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passwordBytes := []byte(password)
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return bcrypt.CompareHashAndPassword(configPasswordBytes, passwordBytes) == nil && username == configUser
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}
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func authLDAP(username string, password string, cfg config.LDAPConfiguration) bool {
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address := cfg.Address
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hostname, _, err := net.SplitHostPort(address)
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if err != nil {
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hostname = address
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}
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var connection *ldap.Conn
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if cfg.Transport == config.LDAPTransportTLS {
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connection, err = ldap.DialTLS("tcp", address, &tls.Config{
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ServerName: hostname,
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InsecureSkipVerify: cfg.InsecureSkipVerify,
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})
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} else {
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connection, err = ldap.Dial("tcp", address)
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}
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if err != nil {
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l.Warnln("LDAP Dial:", err)
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return false
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}
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if cfg.Transport == config.LDAPTransportStartTLS {
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err = connection.StartTLS(&tls.Config{InsecureSkipVerify: cfg.InsecureSkipVerify})
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if err != nil {
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l.Warnln("LDAP Start TLS:", err)
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return false
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}
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}
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defer connection.Close()
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err = connection.Bind(fmt.Sprintf(cfg.BindDN, username), password)
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if err != nil {
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l.Warnln("LDAP Bind:", err)
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return false
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}
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if cfg.SearchFilter == "" && cfg.SearchBaseDN == "" {
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// We're done here.
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return true
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}
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if cfg.SearchFilter == "" || cfg.SearchBaseDN == "" {
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l.Warnln("LDAP configuration: both searchFilter and searchBaseDN must be set, or neither.")
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return false
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}
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// If a search filter and search base is set we do an LDAP search for
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// the user. If this matches precisely one user then we are good to go.
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// The search filter uses the same %s interpolation as the bind DN.
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searchString := fmt.Sprintf(cfg.SearchFilter, username)
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const sizeLimit = 2 // we search for up to two users -- we only want to match one, so getting any number >1 is a failure.
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const timeLimit = 60 // Search for up to a minute...
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searchReq := ldap.NewSearchRequest(cfg.SearchBaseDN, ldap.ScopeWholeSubtree, ldap.DerefFindingBaseObj, sizeLimit, timeLimit, false, searchString, nil, nil)
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res, err := connection.Search(searchReq)
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if err != nil {
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l.Warnln("LDAP Search:", err)
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return false
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}
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if len(res.Entries) != 1 {
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l.Infof("Wrong number of LDAP search results, %d != 1", len(res.Entries))
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return false
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}
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return true
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}
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// Convert an ISO-8859-1 encoded byte string to UTF-8. Works by the
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// principle that ISO-8859-1 bytes are equivalent to unicode code points,
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// that a rune slice is a list of code points, and that stringifying a slice
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// of runes generates UTF-8 in Go.
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func iso88591ToUTF8(s []byte) []byte {
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runes := make([]rune, len(s))
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for i := range s {
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runes[i] = rune(s[i])
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}
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return []byte(string(runes))
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}
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