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

[Justin Stephenson]

Hello Daniel,

Just to clarify the issue:

user 'a.cri.dsullivan at bsdad.uchicago.edu' is a member of IDM POSIX group 
'cri-cri_server_administrators_ipa' which is linked to the external 
group used for the AD trust.

The following HBAC rule is not working to allow SSH access

     [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

==================================================

During the HBAC processing, sssd checks which groups are associated with 
the HBAC rule and adds those groups(just the 
'cri-cri_server_administrators_ipa' group in this case) to the 
memberUser attribute of the HBAC rule sysdb entry.

     (Wed Jul 13 12:07:13 2016) [sssd[be[ipa.cri.uchicago.edu]]] 
[hbac_attrs_to_rule] (0x1000): Processing rule 
[cri-cri_server_administrators_allow_all]
     (Wed Jul 13 12:07:13 2016) [sssd[be[ipa.cri.uchicago.edu]]] 
[sysdb_search_groups] (0x2000): Search groups with filter: 
(&(objectclass=group)(originalDN=cn=cri-cri_server_administrators_ipa,cn=groups,cn=accounts,dc=ipa,dc=cri,dc=uchicago,dc=edu))
     (Wed Jul 13 12:07:13 2016) [sssd[be[ipa.cri.uchicago.edu]]] 
[hbac_user_attrs_to_rule] (0x2000): Added POSIX group 
[cri-cri_server_administrators_ipa] to rule 
[cri-cri_server_administrators_allow_all]

The hbac evaluation reads the originalMemberof attribute of 
'a.cri.dsullivan at bsdad.uchicago.edu' to assess the groups which HBAC 
should match with

     (Wed Jul 13 12:07:13 2016) [sssd[be[ipa.cri.uchicago.edu]]] 
[hbac_eval_user_element] (0x1000): [30] groups for 
[a.cri.dsullivan at bsdad.uchicago.edu]

With debug logging enabled we should see a message such as the following 
when the group is found, but we don't see that in your log output:

     [hbac_eval_user_element]  Added group 
[cri-cri_server_administrators_ipa] for user 
[a.cri.dsullivan at bsdad.uchicago.edu]

We need to understand why this group is being removed from the sysdb, as 
you said the group does not return in id command output after the SSH 
attempt.

It would be great to get full sssd debug logs and a dump of the sssd 
sysdb cache after the first 'id' command is run, and then after the SSH 
attempt is made when the group no longer shows. Note the ldbsearch 
command is included in the 'ldb-tools' rpm

For example:

       ldbsearch -H /var/lib/sss/db/cache_<domain>.ldb > 
ldbsearch-first-id-command.ldb

       ldbsearch -H /var/lib/sss/db/cache_<domain>.ldb > 
ldbsearch-after-ssh-attempt.ldb

Kind regards,
Justin Stephenson


On 07/13/2016 03:14 PM, Sullivan, Daniel [AAA] wrote:
> Jakub, Justin,
>
> Thank you both very much for taking the time to continue helping me resolve this issue.  I apologize for not replying right away; I’ve been dealing with a production issue for most of the morning.
>
> An invocation of ‘id a.cri.dsullivan at bsdad.uchicago.edu<mailto:a.cri.dsullivan at bsdad.uchicago.edu>’ on the IPA DC shows me as a member of the POSIX IPA group (cri_server_administrators_ipa at ipa.cri.uchicago.edu<mailto:cri_server_administrators_ipa at ipa.cri.uchicago.edu>) as well as the AD domain group in the trusted domain (cri-aaa_server_administrators at bsdad.uchicago.edu<mailto:cri-aaa_server_administrators at bsdad.uchicago.edu>).  This remains consistent across any number of successful sshd logins into the DC using my a.cri.dsullivan at bsdad.uchicago<mailto:a.cri.dsullivan at bsdad.uchicago>.edu account, including after clearing the cache on the DC.
>
> On the client, I am seeing some unusual behavior.  If I run the commands 'sss_cache -E; service sssd stop ; rm -rf /var/log/sssd/* ; service sssd start’ , then run ‘id a.cri.dsullivan at bsdad.uchicago.edu<mailto:a.cri.dsullivan at bsdad.uchicago.edu>’, I see the POSIX IPA group as well as the AD domain group as described above (what I presumably want and expect).  However (and this is the unusual part), if I attempt to login via SSH (it will fail with HBAC validation), and then run the ‘id a.cri.dsullivan at bsdad.uchicago.edu<mailto:a.cri.dsullivan at bsdad.uchicago.edu>’ command again , the POSIX IPA group disappears from the list of groups output by the id command.  From what I can tell, this group will not reappear in the group list on the client until the client cache is cleared.  Presumably this behavior is related to the HBAC authentication errors I am experiencing.  I have cleared the cache on both the DC and the client using ssh_cache -E and this behavior is still exhibited.  With respect to output from testing:
>
> 1) The sssd domain log from from the client of the initial id invocation (both groups appear) after clearing the cache (on the client) can be found here (this output contains both groups): https://gist.github.com/dsulli99/7117f8d567cc7cdf727d474b0aeab8da<http://pastebin.com/BpAHfYEP>
> 2) The sssd domain log from the client for the failed sshd login (similar to the output I provided yesterday, however re-captured) can be found here (after this operation the IPA group disappears from the list of groups from the id command): https://gist.github.com/dsulli99/668a8799709ff0cd311b321206591124<http://pastebin.com/tnuAbvmV>
> 3) The DC log (after the client cache is cleared) of my running the id invocation (from the client) can be found here (this is the DC side of 1) from above. https://gist.github.com/dsulli99/a2a5e80b6a8b143afa20024aa40a7b39
> 4) The DC log of the the failed sshd login into the client (this is the DC side of 2) from above is https://gist.github.com/dsulli99/4e3ba53c942ad78d7487ae51da92007e
>
> I really appreciate your help with looking at this issue.  As I said I have another machine built from the same image that this is working fine on.  I am going to keep plugging away at this, I will let you know if I come up with anything.
>
> Dan
>
>
>
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