[Samba] passwd program on samba4

[Dr Michael Cinti]

Hi, my organization uses samba3 with LDAP backend, several non-samba 
attribute are stored in LDAP to manage different service (webmail, web 
service) also LDAP storing many extra-domain users in a different directory.
I would like to migrate to samba4 AD-DC but i need to keep extra-domain 
users and non-samba attributes.
I would like keep all users in LDAP and syncing their passwords from 
samba with "passwd program" but samba4 ignores these directives.

This is my system
Linux anubi.ausl.fe.it 2.6.32-358.6.1.el6.i686 #1 SMP Tue Apr 23 
18:13:20 UTC 2013 i686 i686 i386 GNU/Linux

My samba version (rpm from SOGo Repository but i tested also compiling 
from 4.0.5 sources)
Version 4.0.1-4.centos6.1

My smb.conf

# Global parameters
[global]
         workgroup = AUSLFE
         realm = ausl.fe.it
         netbios name = ANUBI
         server role = active directory domain controller
         idmap_ldb:use rfc2307 = yes
         dns forwarder = 192.168.1.1

         unix password sync = yes
         passwd program = /root/mypasswd.sh %u
         passwd chat = *New*password* %n\n *Retype*new*password* %n\n
         template shell = /bin/bash


I probably forgot some step...
Regards

Michael