Red Hat Bugzilla – Bug 164794
su does not work as expected when kerberos authentication is enabled
Last modified: 2007-11-30 17:07:19 EST
Description of problem:
Running Red Hat Enterprise Linux AS release 4 (Nahant Update 1) using kerberos
authentication against Microsoft Active directory, seems to been broken compared
to previous Red Hat releases (like AS3 U5) regarding the use of su as root. If I
logon with root (console or via ssh), I'm not able to su to a "normal" local
user account :
]# su - guest1
su: incorrect password
Version-Release number of selected component (if applicable):
Red Hat Enterprise Linux AS release 4 (Nahant Update 1)
Logon as root via SSH or console, perform su for a local account like guest1
Su does not ask for a password and despite "minimum_uid = 500" in the krb5.conf
file (user guest1 has uid 504), "it" contacts the MS-AD servers trying to
authenticate the user without asking for a password.
I've disabled SE-Linux to rule out problems from that side, but to no avail.
Comparing the /etc/pam.d/su file with the one on a AS3-U5 server reveals leads,
except for the extra pam_selinux.so lines.
When disabling kerberos authentication, via authconfig, su works like a charm,
no password needed like expected.
A local user shell for guest1 or otherwise a apropriate error message
Enabling "Local authorization is sufficient" via authconfig, enables su for root
on local accounts while kerberos authentication is enabled
Changing component and reassigning.
This also affects cronjobs, as I reported in Bug #144064. That was reported on
FC3, which is more-or-less RHEL 4.
Simplest workaround for this problem and potentially other account modules'
problems is to put 'account sufficient pam_succeed_if.so use_uid uid eq 0' into
the /etc/pam.d/su and /etc/pam.d/crond.
This should be fixed in 2.1.8 and later.
*** Bug 230464 has been marked as a duplicate of this bug. ***
Just verified that we did include this in update 2. Marking as closed, current