Actually, Alfresco provides some CIFS authenticators (passthru, ntlm...), but not for a LDAP subsystem. To solve this problem, we have implemented a component that allows you to use CIFS with openLDAP users.
Note that not all the protocols can be chained, so in order to use the LDAP Samba subsystem, the other CIFS-able subsystems must be deactivated (only one of the subsystems can use CIFS - in fact the first one in the chain):
# The user defined below must be able to execute user search querys in LDAP (administrator) ldap.samba.java.naming.security.principal=cn=admin,dc=example,dc=com ldap.samba.java.naming.security.credentials=secret
IMPORTANT: Each LDAP user needs to store the password as an MD4 hash and we will solve this by adding a sambaSamAccount object class to the user profile. This object class and its attributes are defined in the samba.schema file, which is part of the samba-doc package. To install this new schema, have a look at the documentation for your Linux distribution in the sections talking about how to add an LDAP schema to OpenLDAP. And finally, restart your Alfresco instance.