[Freeipa-users] IPA HBAC access using SSSD for user in trusted AD domain (RHEL 6.8)

Tue Jul 12 22:07:10 UTC 2016

Justin,

I really appreciate you taking the time to respond to me.  This problem is driving me crazy and I will certainly take any help I can get. My suspicion is that the external user group in the policy below was causing the log entry you specified, removing it from the policy does not remediate the problem, even after flushing the client cache.

The way I have this setup is as follows:

1) I created a POSIX group in IPA named 'cri-cri_server_administrators_ipa<https://cri-ksysipadcp2.cri.uchicago.edu/ipa/ui/#cri-cri_server_administrators_ipa>’ and allowed IPA to assign the GID.
2) I created an external group in IPA named 'cri-cri_server_administrators_external<https://cri-ksysipadcp2.cri.uchicago.edu/ipa/ui/#cri-cri_server_administrators_external>’ and added the AD group in the trusted domain as an external member to this group (cri-cri_server_administrators at bsdad.uchicago.edu<mailto:cri-cri_server_administrators at bsdad.uchicago.edu>).
3) I added the group cri-cri_server_administrators_external<https://cri-ksysipadcp2.cri.uchicago.edu/ipa/ui/#cri-cri_server_administrators_external> as a member of 'cri-cri_server_administrators_ipa<https://cri-ksysipadcp2.cri.uchicago.edu/ipa/ui/#cri-cri_server_administrators_ipa>’

The HBAC rule is configured as (removing the external group does not seem to make a difference).

[root at cri-ksysipadcp2 a.cri.dsullivan]# ipa hbacrule-show 'cri-cri_server_administrators_allow_all'
  Rule name: cri-cri_server_administrators_allow_all
  Host category: all
  Service category: all
  Description: Allow anyone in cri-cri_server_administrators at bsdad.uchicago.edu<mailto:cri-cri_server_administrators at bsdad.uchicago.edu> to login to any machine
  Enabled: TRUE
  User Groups: cri-cri_server_administrators_external, cri-cri_server_administrators_ipa
[root at cri-ksysipadcp2 a.cri.dsullivan]#

For example, the problem still persists when the policy is configured in this manner:

[root at cri-ksysipadcp2 a.cri.dsullivan]# ipa hbacrule-show 'cri-cri_server_administrators_allow_all'
  Rule name: cri-cri_server_administrators_allow_all
  Host category: all
  Service category: all
  Description: Allow anyone in cri-cri_server_administrators at bsdad.uchicago.edu<mailto:cri-cri_server_administrators at bsdad.uchicago.edu> to login to any machine
  Enabled: TRUE
  User Groups: cri-cri_server_administrators_ipa

And my login validates against the host in question as follows:

As I said I have this working consistently (i.e. can flush the cash) on another host with the same exact version of IPA and SSSD.  Here is a validation of hbactest (works with either of the two policy configurations above).

[root at cri-ksysipadcp2 a.cri.dsullivan]# ipa hbactest
User name: a.cri.dsullivan at bsdad.uchicago.edu<mailto:a.cri.dsullivan at bsdad.uchicago.edu>
Target host: cri-kcriwebgdp1.cri.uchicago.edu<http://cri-kcriwebgdp1.cri.uchicago.edu>
Service: sshd
--------------------
Access granted: True
--------------------
  Matched rules: cri-cri_server_administrators_allow_all
  Not matched rules: cri-hpc_server_administration
  Not matched rules: Gardner_cluster_login_no_ssh
  Not matched rules: s.cri.ipa-idprovisioner_domain_controllers
[root at cri-ksysipadcp2 a.cri.dsullivan]#

Thank you again for your response.

Best,

Dan

On Jul 12, 2016, at 4:12 PM, Justin Stephenson <jstephen at redhat.com<mailto:jstephen at redhat.com>> wrote:

Hello,

I am assuming this is the AD trust user that is having the problem with HBAC, in my testing I was only allowed access when the HBAC rule is linked to the IDM POSIX AD trust group and not the external group used to retrieve AD trust users. I noticed the following in the logs which is why I mention this:

(Tue Jul 12 13:30:12 2016) [sssd[be[ipa.cri.uchicago.edu<http://ipa.cri.uchicago.edu>]]] [hbac_user_attrs_to_rule] (0x2000): Added non-POSIX group [cri-cri_server_administrators_external] to rule [cri-cri_server_administrators_allow_all]

If this does not help, could you share with us more about the HBAC rule 'cri-cri_server_administrators_allow_all' and how it is configured?

        # ipa hbacrule-show 'cri-cri_server_administrators_allow_all'

Kind regards,

Justin Stephenson

On 07/12/2016 04:11 PM, Sullivan, Daniel [AAA] wrote:

Hi,

I am experiencing an HBAC issue that is proving to be very difficult to diagnose.  It appears very closely related to the issue described in this thread (https://lists.fedorahosted.org/archives/list/sssd-users@lists.fedorahosted.org/thread/DTX4LP5VI2AHANMT4QFXERCN7US2TCUB/), except that clearing the cache does not fix the problem.  I am further stumped by the fact that I have an additional machine that was deployed from an identical VMWare template image which IPA HBAC works correctly on.  From a client perspective I am working with a fully updated version of RHEL 6.8 with ipa-client 3.0.0-50.el6.1 and sssd 1.13.3-22.el6.  We have a domain with 2 IPA domain controllers (RHEL 7.2 and ipa-server 4.2.0-15.el7_2.6.1); I have since shut down one of the two domain controllers and cleared the cache (/var/lib/sssd/db/*) on both clients and restarted sssd (to isolate a potential replication problem between DCs); the HBAC rule validates correctly on the only remaining DC (basically an!
  any any rule). HBAC (the ability to login via sshd) continues to work on only one of the two clients.

>From what I can tell, both clients have the same version of all ipa-client and sssd (and presumably related packages as both clients are fully updated). I have compared their /etc/sshd/sshd_config, /etc/sssd/sssd.conf and all configurations in /etc/pam.d and both systems appear consistent.

I feel that it is worthwhile to mention that I believe that one of the two machines in question (the one that is not working) was bound as a CentrifyDC client.  We are planning on replacing CentrifyDC with FreeIPA (for several reasons), so it is important that we are able to take an existing CentrifyDC client, unbind it, uninstall the CentrifyDC package(s), and install FreeIPA in its place.  Regardless of whether CentrifyDC was previously installed, I feel that my somewhat thorough examination of /etc/sshd/sshd_config and the contents of /etc/pam.d would negate any potential residual configuration from Centrify that would cause this sort of problem.  I have posted my domain log here: http://pastebin.com/41KeSnq4

It is also probably worthwhile to mention that I am authenticating as a user in a trusted domain, although I believe this should be apparent in the the pastebin.

I am hoping that a subject matter expert in IPA and or SSSD would be able to help me further diagnose the access denied by HBAC entry that is present in the pastebin specified above.  As I said, I have cleared /var/lib/sss/db/* and reinstalled IPA-client several times.  I have also rebooted the system completely.

Thank you for considering helping me; I appreciate your time and expertise.

Best,

Dan

********************************************************************************
This e-mail is intended only for the use of the individual or entity to which
it is addressed and may contain information that is privileged and confidential.
If the reader of this e-mail message is not the intended recipient, you are
hereby notified that any dissemination, distribution or copying of this
communication is prohibited. If you have received this e-mail in error, please
notify the sender and destroy all copies of the transmittal.

Thank you
University of Chicago Medicine and Biological Sciences
********************************************************************************

********************************************************************************
This e-mail is intended only for the use of the individual or entity to which
it is addressed and may contain information that is privileged and confidential.
If the reader of this e-mail message is not the intended recipient, you are 
hereby notified that any dissemination, distribution or copying of this
communication is prohibited. If you have received this e-mail in error, please 
notify the sender and destroy all copies of the transmittal. 

Thank you
University of Chicago Medicine and Biological Sciences 
********************************************************************************