Bug 785881

Summary:	List the keytab to pick the princiapl to use instead of guessing
Product:	Red Hat Enterprise Linux 6	Reporter:	Stephen Gallagher <sgallagh>
Component:	sssd	Assignee:	Stephen Gallagher <sgallagh>
Status:	CLOSED ERRATA	QA Contact:	IDM QE LIST <seceng-idm-qe-list>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	6.3	CC:	grajaiya, jgalipea, jzeleny, ksiddiqu, prc
Target Milestone:	rc
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	sssd-1.8.0-2.el6.beta2	Doc Type:	Bug Fix
Doc Text:	Cause: IPA provider uses keytabs to authenticate against IPA server. The approach was to construct expected principal and then try to use it. Consequence: In case the constructed principal wasn't in the keytab, the entire operation failed and the backend wasn't able to connect to IPA server. Fix: The approach has been changed to list all principals in used keytab and pick the most convenient one Result: current implementation has more flexible algorithm to find suitable principal in keytab	Story Points:	---
Clone Of:		Environment:
Last Closed:	2012-06-20 11:54:22 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Stephen Gallagher 2012-01-30 20:19:17 UTC

This bug is created as a clone of upstream ticket:
https://fedorahosted.org/sssd/ticket/781

Apparently, at the moment, we try to construct the principal name for the
local host name and then hope it is matched in the keytab to get a TGT for
operations.

It would be less wasteful to instead open the keytab and list the principals
found in there, then pick the appropriate name in the right form.

This way we will be less prone to failure for misconfigured hosts.
As long as the keytab has a key sssd will always be able to find a key to
use regardless of what the machine thinks is the hostname (which sometimes can
be wrong due to not infrequent /etc/hosts or other misconfigurations)

This would also allow to use native AD principal names for computers (in the
form of FOOBAR$@REALM) for machines joined to an AD domain via samba tools,
without having to add any explicit configuration for it. If it is found give
precedence to the AD form otherwise look for host/fqdn form.

HTH

Comment 1 Jenny Severance 2012-01-30 20:54:35 UTC

please add steps to reproduce/verify this issue. thanks

Comment 2 Jan Zeleny 2012-02-03 07:42:09 UTC

1. Configure SSSD to perform operations against IPA server (CA certificate of IPA server and keytab of the host is of course required)
2. Configure log level 9 for the backend connecting to the IPA server
3. Start SSSD
4. Look into provider log file and look for following messages


Message originating from select_principal_from_keytab about trying to find the most appropriate keytab.

Messages originating from find_principal_in_keytab about trying to find a principal in keytab. At least one of these messages should not have its 'could not find' counterpart.

Comment 5 Jan Zeleny 2012-04-04 11:00:26 UTC

    Technical note added. If any revisions are required, please edit the "Technical Notes" field
    accordingly. All revisions will be proofread by the Engineering Content Services team.
    
    New Contents:
Cause: IPA provider uses keytabs to authenticate against IPA server. The approach was to construct expected principal and then try to use it.
Consequence: In case the constructed principal wasn't in the keytab, the entire operation failed and the backend wasn't able to connect to IPA server.
Fix: The approach has been changed to list all principals in used keytab and pick the most convenient one
Result: current implementation has more flexible algorithm to find suitable principal in keytab

Comment 8 errata-xmlrpc 2012-06-20 11:54:22 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHBA-2012-0747.html