Bug 732935

This fix is a dependency for fixing BZ #732468 in FreeIPA.

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

    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.

    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.

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