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// Copyright 2014 The Gogs Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
// Package ldap provide functions & structure to query a LDAP ldap directory
// For now, it's mainly tested again an MS Active Directory service, see README.md for more information
package ldap
import (
"crypto/tls"
"fmt"
"strings"
log "gopkg.in/clog.v1"
"gopkg.in/ldap.v2"
)
type SecurityProtocol int
// Note: new type must be added at the end of list to maintain compatibility.
const (
SECURITY_PROTOCOL_UNENCRYPTED SecurityProtocol = iota
SECURITY_PROTOCOL_LDAPS
SECURITY_PROTOCOL_START_TLS
)
// Basic LDAP authentication service
type Source struct {
Host string // LDAP host
Port int // port number
SecurityProtocol SecurityProtocol
SkipVerify bool
BindDN string `ini:"bind_dn,omitempty"` // DN to bind with
BindPassword string `ini:",omitempty"` // Bind DN password
UserBase string `ini:",omitempty"` // Base search path for users
UserDN string `ini:"user_dn,omitempty"` // Template for the DN of the user for simple auth
AttributeUsername string // Username attribute
AttributeName string // First name attribute
AttributeSurname string // Surname attribute
AttributeMail string // E-mail attribute
AttributesInBind bool // fetch attributes in bind context (not user)
Filter string // Query filter to validate entry
AdminFilter string // Query filter to check if user is admin
GroupEnabled bool // if the group checking is enabled
GroupDN string `ini:"group_dn"` // Group Search Base
GroupFilter string // Group Name Filter
GroupMemberUID string `ini:"group_member_uid"` // Group Attribute containing array of UserUID
UserUID string `ini:"user_uid"` // User Attribute listed in Group
}
func (ls *Source) sanitizedUserQuery(username string) (string, bool) {
// See http://tools.ietf.org/search/rfc4515
badCharacters := "\x00()*\\"
if strings.ContainsAny(username, badCharacters) {
log.Trace("LDAP: Username contains invalid query characters: %s", username)
return "", false
}
return strings.Replace(ls.Filter, "%s", username, -1), true
}
func (ls *Source) sanitizedUserDN(username string) (string, bool) {
// See http://tools.ietf.org/search/rfc4514: "special characters"
badCharacters := "\x00()*\\,='\"#+;<>"
if strings.ContainsAny(username, badCharacters) || strings.HasPrefix(username, " ") || strings.HasSuffix(username, " ") {
log.Trace("LDAP: Username contains invalid query characters: %s", username)
return "", false
}
return strings.Replace(ls.UserDN, "%s", username, -1), true
}
func (ls *Source) sanitizedGroupFilter(group string) (string, bool) {
// See http://tools.ietf.org/search/rfc4515
badCharacters := "\x00*\\"
if strings.ContainsAny(group, badCharacters) {
log.Trace("LDAP: Group filter invalid query characters: %s", group)
return "", false
}
return group, true
}
func (ls *Source) sanitizedGroupDN(groupDn string) (string, bool) {
// See http://tools.ietf.org/search/rfc4514: "special characters"
badCharacters := "\x00()*\\'\"#+;<>"
if strings.ContainsAny(groupDn, badCharacters) || strings.HasPrefix(groupDn, " ") || strings.HasSuffix(groupDn, " ") {
log.Trace("LDAP: Group DN contains invalid query characters: %s", groupDn)
return "", false
}
return groupDn, true
}
func (ls *Source) findUserDN(l *ldap.Conn, name string) (string, bool) {
log.Trace("Search for LDAP user: %s", name)
if len(ls.BindDN) > 0 && len(ls.BindPassword) > 0 {
// Replace placeholders with username
bindDN := strings.Replace(ls.BindDN, "%s", name, -1)
err := l.Bind(bindDN, ls.BindPassword)
if err != nil {
log.Trace("LDAP: Failed to bind as BindDN '%s': %v", bindDN, err)
return "", false
}
log.Trace("LDAP: Bound as BindDN: %s", bindDN)
} else {
log.Trace("LDAP: Proceeding with anonymous LDAP search")
}
// A search for the user.
userFilter, ok := ls.sanitizedUserQuery(name)
if !ok {
return "", false
}
log.Trace("LDAP: Searching for DN using filter '%s' and base '%s'", userFilter, ls.UserBase)
search := ldap.NewSearchRequest(
ls.UserBase, ldap.ScopeWholeSubtree, ldap.NeverDerefAliases, 0, 0,
false, userFilter, []string{}, nil)
// Ensure we found a user
sr, err := l.Search(search)
if err != nil || len(sr.Entries) < 1 {
log.Trace("LDAP: Failed search using filter '%s': %v", userFilter, err)
return "", false
} else if len(sr.Entries) > 1 {
log.Trace("LDAP: Filter '%s' returned more than one user", userFilter)
return "", false
}
userDN := sr.Entries[0].DN
if userDN == "" {
log.Error(2, "LDAP: Search was successful, but found no DN!")
return "", false
}
return userDN, true
}
func dial(ls *Source) (*ldap.Conn, error) {
log.Trace("LDAP: Dialing with security protocol '%v' without verifying: %v", ls.SecurityProtocol, ls.SkipVerify)
tlsCfg := &tls.Config{
ServerName: ls.Host,
InsecureSkipVerify: ls.SkipVerify,
}
if ls.SecurityProtocol == SECURITY_PROTOCOL_LDAPS {
return ldap.DialTLS("tcp", fmt.Sprintf("%s:%d", ls.Host, ls.Port), tlsCfg)
}
conn, err := ldap.Dial("tcp", fmt.Sprintf("%s:%d", ls.Host, ls.Port))
if err != nil {
return nil, fmt.Errorf("Dial: %v", err)
}
if ls.SecurityProtocol == SECURITY_PROTOCOL_START_TLS {
if err = conn.StartTLS(tlsCfg); err != nil {
conn.Close()
return nil, fmt.Errorf("StartTLS: %v", err)
}
}
return conn, nil
}
func bindUser(l *ldap.Conn, userDN, passwd string) error {
log.Trace("Binding with userDN: %s", userDN)
err := l.Bind(userDN, passwd)
if err != nil {
log.Trace("LDAP authentication failed for '%s': %v", userDN, err)
return err
}
log.Trace("Bound successfully with userDN: %s", userDN)
return err
}
// searchEntry : search an LDAP source if an entry (name, passwd) is valid and in the specific filter
func (ls *Source) SearchEntry(name, passwd string, directBind bool) (string, string, string, string, bool, bool) {
// See https://tools.ietf.org/search/rfc4513#section-5.1.2
if len(passwd) == 0 {
log.Trace("authentication failed for '%s' with empty password", name)
return "", "", "", "", false, false
}
l, err := dial(ls)
if err != nil {
log.Error(2, "LDAP connect failed for '%s': %v", ls.Host, err)
return "", "", "", "", false, false
}
defer l.Close()
var userDN string
if directBind {
log.Trace("LDAP will bind directly via UserDN template: %s", ls.UserDN)
var ok bool
userDN, ok = ls.sanitizedUserDN(name)
if !ok {
return "", "", "", "", false, false
}
} else {
log.Trace("LDAP will use BindDN")
var found bool
userDN, found = ls.findUserDN(l, name)
if !found {
return "", "", "", "", false, false
}
}
if directBind || !ls.AttributesInBind {
// binds user (checking password) before looking-up attributes in user context
err = bindUser(l, userDN, passwd)
if err != nil {
return "", "", "", "", false, false
}
}
userFilter, ok := ls.sanitizedUserQuery(name)
if !ok {
return "", "", "", "", false, false
}
log.Trace("Fetching attributes '%v', '%v', '%v', '%v', '%v' with filter '%s' and base '%s'",
ls.AttributeUsername, ls.AttributeName, ls.AttributeSurname, ls.AttributeMail, ls.UserUID, userFilter, userDN)
search := ldap.NewSearchRequest(
userDN, ldap.ScopeWholeSubtree, ldap.NeverDerefAliases, 0, 0, false, userFilter,
[]string{ls.AttributeUsername, ls.AttributeName, ls.AttributeSurname, ls.AttributeMail, ls.UserUID},
nil)
sr, err := l.Search(search)
if err != nil {
log.Error(2, "LDAP: User search failed: %v", err)
return "", "", "", "", false, false
} else if len(sr.Entries) < 1 {
if directBind {
log.Trace("LDAP: User filter inhibited user login")
} else {
log.Trace("LDAP: User search failed: 0 entries")
}
return "", "", "", "", false, false
}
username := sr.Entries[0].GetAttributeValue(ls.AttributeUsername)
firstname := sr.Entries[0].GetAttributeValue(ls.AttributeName)
surname := sr.Entries[0].GetAttributeValue(ls.AttributeSurname)
mail := sr.Entries[0].GetAttributeValue(ls.AttributeMail)
uid := sr.Entries[0].GetAttributeValue(ls.UserUID)
// Check group membership
if ls.GroupEnabled {
groupFilter, ok := ls.sanitizedGroupFilter(ls.GroupFilter)
if !ok {
return "", "", "", "", false, false
}
groupDN, ok := ls.sanitizedGroupDN(ls.GroupDN)
if !ok {
return "", "", "", "", false, false
}
log.Trace("LDAP: Fetching groups '%v' with filter '%s' and base '%s'", ls.GroupMemberUID, groupFilter, groupDN)
groupSearch := ldap.NewSearchRequest(
groupDN, ldap.ScopeWholeSubtree, ldap.NeverDerefAliases, 0, 0, false, groupFilter,
[]string{ls.GroupMemberUID},
nil)
srg, err := l.Search(groupSearch)
if err != nil {
log.Error(2, "LDAP: Group search failed: %v", err)
return "", "", "", "", false, false
} else if len(sr.Entries) < 1 {
log.Error(2, "LDAP: Group search failed: 0 entries")
return "", "", "", "", false, false
}
isMember := false
for _, group := range srg.Entries {
for _, member := range group.GetAttributeValues(ls.GroupMemberUID) {
if member == uid {
isMember = true
}
}
}
if !isMember {
log.Trace("LDAP: Group membership test failed [username: %s, group_member_uid: %s, user_uid: %s", username, ls.GroupMemberUID, uid)
return "", "", "", "", false, false
}
}
isAdmin := false
if len(ls.AdminFilter) > 0 {
log.Trace("Checking admin with filter '%s' and base '%s'", ls.AdminFilter, userDN)
search = ldap.NewSearchRequest(
userDN, ldap.ScopeWholeSubtree, ldap.NeverDerefAliases, 0, 0, false, ls.AdminFilter,
[]string{ls.AttributeName},
nil)
sr, err = l.Search(search)
if err != nil {
log.Error(2, "LDAP: Admin search failed: %v", err)
} else if len(sr.Entries) < 1 {
log.Error(2, "LDAP: Admin search failed: 0 entries")
} else {
isAdmin = true
}
}
if !directBind && ls.AttributesInBind {
// binds user (checking password) after looking-up attributes in BindDN context
err = bindUser(l, userDN, passwd)
if err != nil {
return "", "", "", "", false, false
}
}
return username, firstname, surname, mail, isAdmin, true
}