Bug 635897 - SELinux is preventing /usr/sbin/lxdm-binary "execute" access on xauth.
SELinux is preventing /usr/sbin/lxdm-binary "execute" access on xauth.
Product: Fedora
Classification: Fedora
Component: lxdm (Show other bugs)
x86_64 Linux
medium Severity medium
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Assigned To: Christoph Wickert
Fedora Extras Quality Assurance
Depends On:
  Show dependency treegraph
Reported: 2010-09-20 19:54 EDT by Adam Williamson
Modified: 2012-04-03 15:55 EDT (History)
8 users (show)

See Also:
Fixed In Version: lxdm-0.4.1-1.fc16
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
Last Closed: 2012-03-23 13:42:29 EDT
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Regression: ---
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Documentation: ---
Verified Versions:
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oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

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Description Adam Williamson 2010-09-20 19:54:38 EDT

SELinux is preventing /usr/sbin/lxdm-binary "execute" access on xauth.

Detailed Description:

SELinux denied access requested by lxdm-binary. It is not expected that this
access is required by lxdm-binary and this access may signal an intrusion
attempt. It is also possible that the specific version or configuration of the
application is causing it to require additional access.

Allowing Access:

You can generate a local policy module to allow this access - see FAQ
(http://docs.fedoraproject.org/selinux-faq-fc5/#id2961385) Please file a bug

Additional Information:

Source Context                system_u:system_r:xdm_t:s0-s0:c0.c1023
Target Context                system_u:object_r:xauth_exec_t:s0
Target Objects                xauth [ file ]
Source                        lxdm-binary
Source Path                   /usr/sbin/lxdm-binary
Port                          <Unknown>
Host                          (removed)
Source RPM Packages           lxdm-0.3.0-0.1.20100921gitcf9b2cbb.fc15
Target RPM Packages           
Policy RPM                    selinux-policy-3.9.3-1.fc14
Selinux Enabled               True
Policy Type                   targeted
Enforcing Mode                Enforcing
Plugin Name                   catchall
Host Name                     (removed)
Platform                      Linux (removed)
                     #1 SMP Fri Aug 27 07:45:05
                              UTC 2010 x86_64 x86_64
Alert Count                   2
First Seen                    Mon 20 Sep 2010 11:46:45 PM EDT
Last Seen                     Mon 20 Sep 2010 11:46:51 PM EDT
Local ID                      9f6caa62-3c74-4c8f-91a4-10266c357c6d
Line Numbers                  

Raw Audit Messages            

node=(removed) type=AVC msg=audit(1285040811.374:15): avc:  denied  { execute } for  pid=1479 comm="lxdm-binary" name="xauth" dev=dm-0 ino=21734 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:xauth_exec_t:s0 tclass=file

node=(removed) type=SYSCALL msg=audit(1285040811.374:15): arch=c000003e syscall=59 success=no exit=-13 a0=12cb715 a1=12d1950 a2=12cef70 a3=7fffd9cfa870 items=0 ppid=1 pid=1479 auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 tty=(none) ses=1 comm="lxdm-binary" exe="/usr/sbin/lxdm-binary" subj=system_u:system_r:xdm_t:s0-s0:c0.c1023 key=(null)

Hash String generated from  catchall,lxdm-binary,xdm_t,xauth_exec_t,file,execute
audit2allow suggests:

#============= xdm_t ==============
allow xdm_t xauth_exec_t:file execute;
Comment 1 Daniel Walsh 2010-09-22 17:19:50 EDT
This looks like you don't have pam_selinux setup correctly in your pam files.
Comment 2 Christoph Wickert 2010-09-26 06:26:30 EDT
I don't think so. We had this already and you said it was fine. This is /etc/pam.d/lxdm from the package:

auth     [success=done ignore=ignore default=bad] pam_selinux_permit.so
auth       required    pam_succeed_if.so user != root quiet
auth       required    pam_env.so
auth       substack    system-auth
auth       optional    pam_gnome_keyring.so
account    required    pam_nologin.so
account    include     system-auth
password   include     system-auth
session    required    pam_selinux.so close
session    required    pam_loginuid.so
session    optional    pam_console.so
session    required    pam_selinux.so open
session    optional    pam_keyinit.so force revoke
session    required    pam_namespace.so
session    optional    pam_gnome_keyring.so auto_start
session    include     system-auth

What's wrong with it?
Comment 3 Daniel Walsh 2010-09-26 06:38:32 EDT
Why is it running xauth before calling pam_selinux.so open?
Comment 4 Christoph Wickert 2010-09-26 09:06:41 EDT
Dgod, can you give us some insight here?
Comment 5 dgod.osa 2010-09-26 13:16:47 EDT
lxdm use xauth to create xauth file of xserver.
the xserver is started by lxdm before pam session.

slim likely do the samething.

I don't think it's a security problem, if neccesary, I can rewrite this part.
Comment 6 Daniel Walsh 2010-09-27 09:24:53 EDT
As long as I understand this is normal.  I do not have a problem adding the access.

You can add these rules for now using

# grep avc /var/log/audit/audit.log | audit2allow -M mypol
# semodule -i mypol.pp

Fixed in selinux-policy-3.9.5-7.fc14
Comment 7 Fedora Update System 2012-03-21 16:49:49 EDT
lxdm-0.4.1-1.fc17 has been submitted as an update for Fedora 17.
Comment 8 Fedora Update System 2012-03-21 16:52:28 EDT
lxdm-0.4.1-1.fc16 has been submitted as an update for Fedora 16.
Comment 9 Fedora Update System 2012-03-21 16:59:15 EDT
lxdm-0.4.1-1.fc15 has been submitted as an update for Fedora 15.
Comment 10 Fedora Update System 2012-03-21 21:55:10 EDT
Package lxdm-0.4.1-1.fc16:
* should fix your issue,
* was pushed to the Fedora 16 testing repository,
* should be available at your local mirror within two days.
Update it with:
# su -c 'yum update --enablerepo=updates-testing lxdm-0.4.1-1.fc16'
as soon as you are able to.
Please go to the following url:
then log in and leave karma (feedback).
Comment 11 Fedora Update System 2012-03-23 13:42:29 EDT
lxdm-0.4.1-1.fc17 has been pushed to the Fedora 17 stable repository.  If problems still persist, please make note of it in this bug report.
Comment 12 Fedora Update System 2012-04-03 15:53:17 EDT
lxdm-0.4.1-1.fc15 has been pushed to the Fedora 15 stable repository.  If problems still persist, please make note of it in this bug report.
Comment 13 Fedora Update System 2012-04-03 15:55:14 EDT
lxdm-0.4.1-1.fc16 has been pushed to the Fedora 16 stable repository.  If problems still persist, please make note of it in this bug report.

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