On Fri, Jan 11, 2019 at 01:44:00PM +0000, Joakim Tjernlund wrote:
On Fri, 2019-01-11 at 13:10 +0100, Sumit Bose wrote:
> CAUTION: This email originated from outside of the organization. Do not click links
or open attachments unless you recognize the sender and know the content is safe.
> On Wed, Jan 09, 2019 at 11:28:24PM -0000, Carwyn Edwards wrote:
> > We've just been bitten by the Samba 4.8 rebase in CentOS/RHEL 7.6,
specifically this bit from the RHEL 7.6 release notes:
> > "The smbd service no longer queries user and group information from Active
Directory domain controllers and NT4 primary domain controllers directly. Installations
with the security parameter set to ads or domain now require that the winbindd service is
> > Which stems from the Samba 4.8 release notes:
> > "Domain member setups require winbindd - Setups with "security =
domain" or "security = ads" require a
> > running 'winbindd' now. The fallback that smbd directly contacts domain
controllers is gone."
> > The RHEL 7 Systems Administration Guide now states:
> > "Red Hat only supports running Samba as a server with the winbindd service
to provide domain users and groups to the local system. Due to certain limitations, such
as missing Windows access control list (ACL) support and NT LAN Manager (NTLM) fallback,
the System Security Services Daemon (SSSD) is not supported."
> > Now in RHEL 7.5 we were managing to use SSSD with Samba, the only real glitch
(we think) was that SIDs rather than names showing up in the share ACLs. Unfortunately Red
Hat support are sticking to the above like glue so far.
> > My question to this list is, given the changes to Samba from 4.8, is there a
way to get RHEL 7.6 winbind (for Samba) to use SSSD for the lookups that works?
> > I noticed that the package sssd-winbind-idmap that ships in RHEL 7.6 contains
the library /usr/lib64/samba/idmap/sss.so which from the idmap_sss man page states:
> > "The idmap_sss module provides a way to call SSSD to map UIDs/GIDs and
> > With a config example:
> > [global]
> > ...
> > idmap config * : backend = sss
> > (There an open bugzilla and pagure bug about this example being wrong as sss is
> > There's also the following file in the package sssd-client
> > /usr/lib64/cifs-utils/cifs_idmap_sss.so
> > Which is controlled via the alternatives system.
> > I'm not entirely sure how these differ yet but I get the impression that
the intention somewhere is to re-enable Samba to Winbind to SSSD lookups? Am I on the
right track? Could this be made to work with the versions in RHEL 7.6 if so?
> Yes, you are right.
> I updated the idmap_sss man page in a very recent commit
> With idmap_sss you can make sure that winbind will use the same ID
> mapping as SSSD so that there is no need to change the ownership of
> files or directories.
I never managed to work out the difference between SSSD's idmap and winbind's ad
what is the difference ?
If you use SSSD's 'ldap_id_mapping = false' then SSSD will read the UIDs
and GIDs from AD as does idmap_ad.
With 'ldap_id_mapping = true' then SSSD uses a similar scheme as Samba's
idmap_rid or idmap_autorid. But in general the starting point for the
mapping would be different so that it would no be easy to get the same
mapping with those.
> Besides the idmap configuration in smb.conf you have to make sure that
> the system is joined the AD with the 'net ads join' command which is
> also used by realmd in the default RHEL/CentOS settings. This is needed
> because winbind expects some extra data added to some internal libraries
> to be able to work properly.
Should not the in git adcli work as well? When will you release it?
Yes, but the devil is in the details, with current versions of Samba
'net changesecretpw' which is used by adcli (and e.g. by msktutil as
well) does not work properly with an empty secrets.tdb. There is a
workaround but for the time being 'net ads join' would be more
> If you have SSSD's version of libwbclient installed please remove the
> sssd-libwbclient package and install Samba's libwbclient package if it
> is missing (but I guess it is already present as a dependency of
Is SSSD's wbclient obsolete or just not finished yet?
I would say it becomes obsolete for more and more use-cases. There were
always limitations like no NTLM auth, no access with IP addresses, ...
To add what is missing would require to implement the communication to
various AD RPC services which we never planned. To do this you either
have to implement it from scratch which would be a more than major
effort or use all the related Samba libraries which are already the core
of winbind. So letting Samba's smbd use winbind directly looks more
straight forward and reliable.
> > There is also a nice summary by Erinn earlier on this list
> > which describes some current pitfalls. In this posting the idmap
> > 'backend = ad' is used. As long as you are not using SSSD's
> > (ldap_id_mapping = false) or overrides 'backend = ad' will work as well
> > because both winbind and SSSD will use the IDs stored in AD.
> > /usr/lib64/cifs-utils/cifs_idmap_sss.so is a helper for the cifs.ko
> > kernel module which uses an upcall to let the user-space map SIDs to
> > POSIX IDs and back. It is needed on clients where you want to mount
> > CIFS/SMB shares into the file-system. Winbind is not needed for this
> > use-case.
> > HTH
> > bye,
> > Sumit
> sssd-users mailing list -- sssd-users(a)lists.fedorahosted.org
> To unsubscribe send an email to sssd-users-leave(a)lists.fedorahosted.org
> Fedora Code of Conduct: https://getfedora.org/code-of-conduct.html
> List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines
> List Archives: