syncthing/lib/api/api_auth.go

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// 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
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at https://mozilla.org/MPL/2.0/.
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package api
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import (
"crypto/tls"
"fmt"
"net"
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"net/http"
"strings"
"time"
ldap "github.com/go-ldap/ldap/v3"
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"github.com/syncthing/syncthing/lib/config"
"github.com/syncthing/syncthing/lib/events"
"github.com/syncthing/syncthing/lib/rand"
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"github.com/syncthing/syncthing/lib/sync"
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)
var (
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sessions = make(map[string]bool)
sessionsMut = sync.NewMutex()
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)
func emitLoginAttempt(success bool, username, address string, evLogger events.Logger) {
evLogger.Log(events.LoginAttempt, map[string]interface{}{
"success": success,
"username": username,
"remoteAddress": address,
})
if !success {
l.Infof("Wrong credentials supplied during API authorization from %s", address)
}
}
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 hasValidAPIKeyHeader(r, guiCfg) {
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next.ServeHTTP(w, r)
return
}
// Exception for REST calls that don't require authentication.
if strings.HasPrefix(r.URL.Path, "/rest/noauth") {
next.ServeHTTP(w, r)
return
}
cookie, err := r.Cookie(cookieName)
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if err == nil && cookie != nil {
sessionsMut.Lock()
_, ok := sessions[cookie.Value]
sessionsMut.Unlock()
if ok {
next.ServeHTTP(w, r)
return
}
}
l.Debugln("Sessionless HTTP request with authentication; this is expensive.")
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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)
}
username, password, ok := r.BasicAuth()
if !ok {
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error()
return
}
authOk := auth(username, password, guiCfg, ldapCfg)
if !authOk {
usernameIso := string(iso88591ToUTF8([]byte(username)))
passwordIso := string(iso88591ToUTF8([]byte(password)))
authOk = auth(usernameIso, passwordIso, guiCfg, ldapCfg)
if authOk {
username = usernameIso
}
}
if !authOk {
emitLoginAttempt(false, username, r.RemoteAddr, evLogger)
error()
return
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}
sessionid := rand.String(32)
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sessionsMut.Lock()
sessions[sessionid] = true
sessionsMut.Unlock()
// Best effort detection of whether the connection is HTTPS --
// either directly to us, or as used by the client towards a reverse
// proxy who sends us headers.
connectionIsHTTPS := r.TLS != nil ||
strings.ToLower(r.Header.Get("x-forwarded-proto")) == "https" ||
strings.Contains(strings.ToLower(r.Header.Get("forwarded")), "proto=https")
// If the connection is HTTPS, or *should* be HTTPS, set the Secure
// bit in cookies.
useSecureCookie := connectionIsHTTPS || guiCfg.UseTLS()
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http.SetCookie(w, &http.Cookie{
Name: cookieName,
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Value: sessionid,
MaxAge: 0,
Secure: useSecureCookie,
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})
emitLoginAttempt(true, username, r.RemoteAddr, evLogger)
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next.ServeHTTP(w, r)
})
}
func auth(username string, password string, guiCfg config.GUIConfiguration, ldapCfg config.LDAPConfiguration) bool {
if guiCfg.AuthMode == config.AuthModeLDAP {
return authLDAP(username, password, ldapCfg)
} else {
return authStatic(username, password, guiCfg)
}
}
func authStatic(username string, password string, guiCfg config.GUIConfiguration) bool {
return guiCfg.CompareHashedPassword(password) == nil && username == guiCfg.User
}
func authLDAP(username string, password string, cfg config.LDAPConfiguration) bool {
address := cfg.Address
hostname, _, err := net.SplitHostPort(address)
if err != nil {
hostname = address
}
var connection *ldap.Conn
if cfg.Transport == config.LDAPTransportTLS {
connection, err = ldap.DialTLS("tcp", address, &tls.Config{
ServerName: hostname,
InsecureSkipVerify: cfg.InsecureSkipVerify,
})
} else {
connection, err = ldap.Dial("tcp", address)
}
if err != nil {
l.Warnln("LDAP Dial:", err)
return false
}
if cfg.Transport == config.LDAPTransportStartTLS {
err = connection.StartTLS(&tls.Config{InsecureSkipVerify: cfg.InsecureSkipVerify})
if err != nil {
l.Warnln("LDAP Start TLS:", err)
return false
}
}
defer connection.Close()
err = connection.Bind(ldapTemplateBindDN(cfg.BindDN, username), password)
if err != nil {
l.Warnln("LDAP Bind:", err)
return false
}
if cfg.SearchFilter == "" && cfg.SearchBaseDN == "" {
// We're done here.
return true
}
if cfg.SearchFilter == "" || cfg.SearchBaseDN == "" {
l.Warnln("LDAP configuration: both searchFilter and searchBaseDN must be set, or neither.")
return false
}
// If a search filter and search base is set we do an LDAP search for
// the user. If this matches precisely one user then we are good to go.
// The search filter uses the same %s interpolation as the bind DN.
searchString := fmt.Sprintf(cfg.SearchFilter, username)
const sizeLimit = 2 // we search for up to two users -- we only want to match one, so getting any number >1 is a failure.
const timeLimit = 60 // Search for up to a minute...
searchReq := ldap.NewSearchRequest(cfg.SearchBaseDN, ldap.ScopeWholeSubtree, ldap.DerefFindingBaseObj, sizeLimit, timeLimit, false, searchString, nil, nil)
res, err := connection.Search(searchReq)
if err != nil {
l.Warnln("LDAP Search:", err)
return false
}
if len(res.Entries) != 1 {
l.Infof("Wrong number of LDAP search results, %d != 1", len(res.Entries))
return false
}
return true
}
func ldapTemplateBindDN(bindDN string, username string) string {
// Check if formatting directives are included in the ldapTemplateBindDN - if so add username.
// (%%s is a literal %s - unlikely for LDAP, but easy to handle here).
if strings.Count(bindDN, "%s") != strings.Count(bindDN, "%%s") {
bindDN = fmt.Sprintf(bindDN, username)
}
return bindDN
}
// Convert an ISO-8859-1 encoded byte string to UTF-8. Works by the
// principle that ISO-8859-1 bytes are equivalent to unicode code points,
// that a rune slice is a list of code points, and that stringifying a slice
// of runes generates UTF-8 in Go.
func iso88591ToUTF8(s []byte) []byte {
runes := make([]rune, len(s))
for i := range s {
runes[i] = rune(s[i])
}
return []byte(string(runes))
}