New subject: Different SSSD LDAP search filters for specific PAM services

26 Oct 2012


      On 10/25/2012 04:14 PM, Jakub Hrozek wrote:
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On Thu, Oct 25, 2012 at 01:48:49PM +0200, Tomas Brandysky wrote:
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On 10/25/2012 11:36 AM, Sumit Bose wrote:
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On Thu, Oct 25, 2012 at 10:36:05AM +0200, Tomas Brandysky wrote:
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Hello,
we're upgrading from Centos 5.8 to Centos 6.3 and have realized few
things have changed in the system.
We're using LDAP authentication (nss_ldap package) on our Centos 5.8
servers and have different PAM ldap configuration files configured to be
used for specific PAM services at the moment.
Here is the example of our setup:
/etc/pam.d/service1:
 auth        sufficient    pam_ldap.so config=/etc/ldap_service1.conf
/etc/pam.d/service2:
 auth        sufficient    pam_ldap.so config=/etc/ldap_service2.conf
Thus we can use specific LDAP filters for various different services as
not all users having access to one service also have access to other
services on the same server.
Now we're facing the problem to manage the same functionality with
System Security Services Daemon (SSSD) which was newly presented with
RHEL 6.
We didn't find out so far how to specify custom sssd configuration file
(or specific part of the configuration section/domain) in PAM service
configuration. According to documentation only these options can be
specified when using pam_sss module: [forward_pass] [use_first_pass]
[use_authtok].
None of them can be used to make a difference in a ldap filter to be used.
Is there a way how to configure specific search filters depending on PAM
service ?
Thank you for any suggestion
I think what you are looking for is covered in
https://fedorahosted.org/sssd/ticket/1021.
yes, that's exactly what I miss in sssd.
I'm surprised such a feature isn't supported yet as the same goal could
be accomplished in RHEL4/5 releases with older methods. I see this as a
step back. Is there some real possibility to have this feature in some
later release which could come as update in RHEL 6 ?
I don't think we are tracking this feature request for RHEL6. If
you need the functionality in RHEL6, feel to propose it through the
support.
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...
If you only want to allow/deny access for specific users to specific
service you can add an attribute to the user objects in the LDAP server
listing the allowed PAM services and use ldap_user_authorized_service.
See sssd-ldap man page for details.
I know about ldap_user_authorized_service but I need to specify a
combination of service and host access. I can't effort to grant users
access to ssh service globaly when they can access ssh only on some of
dozens servers we have.
You can also use a comma-separated list in the ldap_access_order
parameter of sssd.conf and then define both service and host for a user.
this is not a solution because defining service for user in LDAP means
to grant user access to this service not only on a particular server but
on all servers the same user can access too (for example because of some
other services).
This is real scenario:
- two servers both running openvpn and ssh services - both configured to
authenticate users against LDAP
- I want user "one" to have access to:
 - openvpn service on server1
 - ssh service on server2
I'm not able to manage this with sssd even though I try it with comma-
separated list in the ldap_access_order parameter. I don't think this
scenario is so rare in other companies too. This is a quite common
practice in larger companies maintaining dozens of servers and services
to grant users access to specific services on specific servers only (as
we can do easily with pam_ldap).
I will be very surprised if many other companies won't request this
feature being present in sssd if this is a new official way how to
handle LDAP authentication in RHEL 6.
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For a finer-grained access control, you probably want IPA's HBAC as
Sumit said.
I got a look to at IPA's HBAC and it seems to be overkill to me. I can
imagine such a solution in very large enterprises where kinda more
sophisticated integrated security information management solution might
come in handy.
I think our company(as many others) will stick with "old" pam_ldap
solution which was there working since RHEL4. At least until this
feature is integrated to sssd.
Tomas

Re: [SSSD-users] Different SSSD LDAP search filters for specific PAM services