RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.
Bug 732935 - Add LDAP provider option to set LDAP_OPT_X_SASL_NOCANON
Summary: Add LDAP provider option to set LDAP_OPT_X_SASL_NOCANON
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: sssd
Version: 6.1
Hardware: Unspecified
OS: Unspecified
medium
medium
Target Milestone: rc
: ---
Assignee: Stephen Gallagher
QA Contact: Chandrasekar Kannan
URL:
Whiteboard:
Depends On:
Blocks: 732468 748866
TreeView+ depends on / blocked
 
Reported: 2011-08-24 08:11 UTC by Marko Myllynen
Modified: 2020-05-02 16:24 UTC (History)
7 users (show)

Fixed In Version: sssd-1.5.1-49.el6
Doc Type: Bug Fix
Doc Text:
Cause: In some cases when SASL is used, libldap might try to canonicalize the hostname by doing a reverse lookup. Consequence: The LDAP request might block. Also if PTR record was wrong, SSSD wouldn't authenticate against the server at all. Fix: An SSSD configuration directive has been implemented, allowing to turn canonicalization inside libldap on or off. The canonicalization is off by default. Result: SASL/GSSAPI works fine even wen the PTR is wrong.
Clone Of:
: 748866 (view as bug list)
Environment:
Last Closed: 2011-12-06 16:39:31 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
FedoraHosted SSSD 978 0 None None None Never
Github SSSD sssd issues 2020 0 None None None 2020-05-02 16:24:31 UTC
Red Hat Product Errata RHBA-2011:1529 0 normal SHIPPED_LIVE sssd bug fix and enhancement update 2011-12-06 00:50:20 UTC

Description Marko Myllynen 2011-08-24 08:11:34 UTC 
Description of problem:
From https://fedorahosted.org/sssd/ticket/978

In some cases when SASL is used, openldap might try to canonicalize the hostname by doing a reverse lookup. This might be a blocking call because openldap uses glibc's getnameinfo (The openldap function is ldap_pvt_get_hname).

It is possible to turn off this check by setting LDAP_OPT_X_SASL_NOCANON.

It is not only a problem about blocking on DNS calls. It may also cause failures to get a ticket because the PTR is wrong. Bad DNs configuration for reverse addresses is very common, especially in test environments, and small networks.
Comment 2 Stephen Gallagher 2011-08-24 12:42:52 UTC 
This fix is a dependency for fixing BZ #732468 in FreeIPA.
Comment 5 Kaushik Banerjee 2011-09-27 13:38:41 UTC 
Steps to verify:

1. Configure dns as:
A record  : ldap.example.com -> 10.65.201.57
PTR record: 10.65.201.57 -> xyz.example.com


2. Configure sssd for gssapi auth.
[domain/gssapi]
debug_level = 9
id_provider = ldap
ldap_uri = ldap://ldap.example.com
ldap_search_base = dc=example,dc=com
auth_provider = krb5
krb5_server = ldap.example.com
krb5_realm = EXAMPLE.COM
ldap_sasl_mech = GSSAPI
ldap_sasl_authid = host/client.example.com
ldap_krb5_init_creds = true
ldap_krb5_ticket_lifetime = 120
krb5_validate = True
krb5_lifetime = 150m

3. Lookup of a ldap user and auth as the user should succeed.( Note that we have to set " rdns = false" in /etc/krb5.conf )

4. Now, set "ldap_sasl_canonicalize = true", restart sssd. Lookup and auth of the ldap user would fail since due to incorrect PTR record, hostname cannot be canonicalized.

Verified in version:
# rpm -qi sssd | head
Name        : sssd                         Relocations: (not relocatable)
Version     : 1.5.1                             Vendor: Red Hat, Inc.
Release     : 52.el6                        Build Date: Tue 20 Sep 2011 09:11:03 PM IST
Install Date: Mon 26 Sep 2011 05:56:30 PM IST      Build Host: x86-010.build.bos.redhat.com
Group       : Applications/System           Source RPM: sssd-1.5.1-52.el6.src.rpm
Size        : 3550647                          License: GPLv3+
Signature   : (none)
Packager    : Red Hat, Inc. <http://bugzilla.redhat.com/bugzilla>
URL         : http://fedorahosted.org/sssd/
Summary     : System Security Services Daemon
Comment 6 Jan Zeleny 2011-10-27 14:03:56 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: In some cases when SASL is used, libldap might try to canonicalize the hostname by doing a reverse lookup.
Consequence: The LDAP request might block. Also if PTR record was wrong, SSSD wouldn't authenticate against the server at all.
Fix: A configuration directive has been implemented allowing to turn off canonicalization in libldap.
Result: If there are some issues with the DNS / network which would cause unwanted behavior of SSSD such as blocking calls, it is possible to turn canonicalization off.
Comment 7 Jakub Hrozek 2011-10-27 14:14:02 UTC 
    Technical note updated. If any revisions are required, please edit the "Technical Notes" field
    accordingly. All revisions will be proofread by the Engineering Content Services team.
    
    Diffed Contents:
@@ -1,4 +1,4 @@
 Cause: In some cases when SASL is used, libldap might try to canonicalize the hostname by doing a reverse lookup.
 Consequence: The LDAP request might block. Also if PTR record was wrong, SSSD wouldn't authenticate against the server at all.
-Fix: A configuration directive has been implemented allowing to turn off canonicalization in libldap.
+Fix: An SSSD configuration directive has been implemented, allowing to turn canonicalization inside libldap on or off. The canonicalization is off by default.
-Result: If there are some issues with the DNS / network which would cause unwanted behavior of SSSD such as blocking calls, it is possible to turn canonicalization off.+Result: SASL/GSSAPI works fine even wen the PTR is wrong.
Comment 8 errata-xmlrpc 2011-12-06 16:39:31 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-2011-1529.html
Note You need to log in before you can comment on or make changes to this bug.