[Pkg-samba-maint] Bug#474108: samba domain controller disregarding 'valid users' settings

Josip Rodin joy at debbugs.entuzijast.net
Thu Apr 3 12:00:13 UTC 2008

Package: samba
Version: 3.0.24-6etch9
Severity: important


It appears that once you set a Samba server to be a primary domain
controller that authenticates via a back-end LDAP server, it can no longer
serve as a meaningful file server, because the 'valid users' setting
simply doesn't work any more. It works on the normal Sambas which are
set to use 'security = domain' with the Samba PDC, but not on the
controller itself, for some reason.

This behaviour may not be a bug in itself (I don't have any idea about the
motivation, I suppose it could be sensible), but it is not documented in
the manual page or the HOWTO, and the code doesn't warn me that the
'valid users' setting was ignored intentionally (if it has). It allows for
information disclosure (shares that are accessible to the wrong users,
even though you set them not to be), so it's a security problem, really.
But I've kept the bug at a non-RC severity because I'm unsure of the
reasoning, and because this isn't a particularly common setup, I guess.

I'm not sure what's happening there, really... the smbd/service.c:575
check succeeds where it shouldn't. Annoyingly enough, you have to up
the general debug level to 10 to get anything useful out of
smbd/share_access.c:user_ok_token(). Even then, it doesn't show anything

[2008/04/03 13:42:09, 10] smbd/share_access.c:user_ok_token(229)
  user_ok_token: share nagios is ok for unix user joy
[2008/04/03 13:42:09, 10] smbd/share_access.c:is_share_read_only_for_token(271)
  is_share_read_only_for_user: share nagios is read-only for unix user joy

The else cases of the lp_invalid_users(snum), lp_valid_users(snum) and
lp_onlyuser(snum) should have DEBUG(20, ...) messages, because this way
I don't really know if it's those NULL comparisons which have failed, or
if the problems were the token_contains_name_in_list() checks within them.

Now I'd have to edit the code, recompile and test it on a production PDC :/
I'll have to go reproduce it in a lab setting...

Please fix this. TIA.

     2. That which causes joy or happiness.

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