samba-mirror/docs/textdocs/UNIX_SECURITY.txt

!==
!== UNIX_SECURITY.txt for Samba release 2.0.4 18 May 1999
!==
Contributor:	John H Terpstra <jht@samba.org>
Date:		July 5, 1998
Status:		Current

Subject:	SETTING UNIX FILE SYSTEM SECURITY
===============================================================================
The following excerpt from a bug report demonstrates the need to
understand Unix file system security and to manage it correctly.

Quote:
======
> We are unable to keep individual users from mapping to any other user's
> home directory once they have supplied a valid password! They only need
> to enter their own password. I have not found *any* method that I can
> use to configure samba to enforce that only a user may map their own
> home directory.
> 
> User xyzzy can map his home directory. Once mapped user xyzzy can also map
> *anyone* elses home directory!

ANSWER:
=======
This is not a security flaw, it is by design. Samba allows
users to have *exactly* the same access to the UNIX filesystem
as they would if they were logged onto the UNIX box, except
that it only allows such views onto the file system as are
allowed by the defined shares.

This means that if your UNIX home directories are set up
such that one user can happily cd into another users
directory and do an ls, the UNIX security solution is to 
change the UNIX file permissions on the users home directories
such that the cd and ls would be denied.

Samba tries very had not to second guess the UNIX administrators
security policies, and trusts the UNIX admin to set
the policies and permissions he or she desires.

Samba does allow the setup you require when you have set the
"only user = yes" option on the share, is that you have not set the
valid users list for the share.

Note that only user works in conjunction with the users= list,
so to get the behavior you require, add the line :

users = %S

this is equivalent to:

valid users = %S

to the definition of the [homes] share, as recommended in
the smb.conf man page.