Bug 248838 - SELinux is preventing /usr/sbin/ntpd (ntpd_t) "read write" access to /dev/ptmx (ptmx_t).
Summary: SELinux is preventing /usr/sbin/ntpd (ntpd_t) "read write" access to /dev/ptm...
Alias: None
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: selinux-policy (Show other bugs)
(Show other bugs)
Version: 5.0
Hardware: All Linux
Target Milestone: ---
: ---
Assignee: Daniel Walsh
QA Contact:
Depends On:
TreeView+ depends on / blocked
Reported: 2007-07-19 04:45 UTC by manoj
Modified: 2014-11-28 09:14 UTC (History)
3 users (show)

Fixed In Version: RHBA-2008-0465
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
Last Closed: 2008-05-21 16:05:20 UTC
Type: ---
Regression: ---
Mount Type: ---
Documentation: ---
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

Attachments (Terms of Use)

External Trackers
Tracker ID Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2008:0465 normal SHIPPED_LIVE selinux-policy bug fix update 2008-05-20 14:36:31 UTC

Description manoj 2007-07-19 04:45:11 UTC
Description of problem:
    SELinux is preventing /usr/sbin/ntpd (ntpd_t) "read write" access to
    /dev/ptmx (ptmx_t).

Detailed Description
    SELinux denied access requested by /usr/sbin/ntpd. It is not expected that
    this access is required by /usr/sbin/ntpd 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
    Please file a http://bugzilla.redhat.com/bugzilla/enter_bug.cgi against

Allowing Access
    Sometimes labeling problems can cause SELinux denials.  You could try to
    restore the default system file context for /dev/ptmx, restorecon -v
    /dev/ptmx. There is currently no automatic way to allow this access.
    Instead, you can generate a local policy module to allow this access - see
    http://fedora.redhat.com/docs/selinux-faq-fc5/#id2961385 - or you can
    disable SELinux protection entirely for the application. Disabling SELinux
    protection is not recommended. Please file a
    http://bugzilla.redhat.com/bugzilla/enter_bug.cgi against this package.
    Changing the "ntpd_disable_trans" boolean to true will disable SELinux
    protection this application: "setsebool -P ntpd_disable_trans=1."

    The following command will allow this access:
    setsebool -P ntpd_disable_trans=1

Additional Information        

Source Context                root:system_r:ntpd_t
Target Context                system_u:object_r:ptmx_t
Target Objects                /dev/ptmx [ chr_file ]
Affected RPM Packages         ntp-4.2.2p1-5.el5 [application]
Policy RPM                    selinux-policy-2.4.6-30.el5
Selinux Enabled               True
Policy Type                   targeted
MLS Enabled                   True
Enforcing Mode                Permissive
Plugin Name                   plugins.disable_trans
Host Name                     Rhel5.test.com
Platform                      Linux Rhel5.test.com 2.6.18-8.el5 #1 SMP Fri Jan
                              26 14:15:14 EST 2007 x86_64 x86_64
Alert Count                   4
Line Numbers                  

Raw Audit Messages            

avc: denied { read, write } for comm="ntpd" dev=tmpfs egid=0 euid=0
exe="/usr/sbin/ntpd" exit=0 fsgid=0 fsuid=0 gid=0 items=0 name="ptmx"
path="/dev/ptmx" pid=8086 scontext=root:system_r:ntpd_t:s0 sgid=0
subj=root:system_r:ntpd_t:s0 suid=0 tclass=chr_file
tcontext=system_u:object_r:ptmx_t:s0 tty=(none) uid=0

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
Actual results:

Expected results:

Additional info:

I have Xandros Bridgeways on RHEL5 (original release, no
updates). I have enabled selinux in permissive mode. When i start the TimeServer
from Bridgeways UI I get the above error.
I don't believe this has anything to do with the product I have installed however.

Comment 1 Daniel Walsh 2007-07-19 13:23:45 UTC
Could you put this machine in permissive mode and then run ntpd to gather all of
the avc messages.  The attach them to this bugzilla

setenforce 0
service ntpd restart
setenforce 1
grep avc /var/log/audit/audit.log > /tmp/avc.txt

Comment 2 manoj 2007-07-20 08:56:19 UTC
The report which i had pasted in this bug was with selinux enabled in permissive
mode only.
However when i start ntpd (/etc/init.d/ntpd start) from the command line on
Plain Rhel5 system i couldn't reproduce this bug .But after installing
Bridgeways on my Redhat system and starting  Time Server thereafter from
Bridgeways UI i'm getting this bug.

Comment 3 Daniel Walsh 2007-07-20 13:38:14 UTC
Fixed in selinux-policy-2.4.6-80

If you want to add these rules you can simply execute

grep ntp /var/log/audit/audit.log | audit2allow -M myntp
semodule -i myntp.pp

Comment 4 manoj 2007-07-23 03:25:35 UTC
Does this mean that bug is with SeLinux Policy 2.4.6-30.el5??? or with
BridgeWays Tool which I'm using on Rhel5???

Comment 5 Daniel Walsh 2007-07-23 14:10:02 UTC
SELinux policy is not allowing ntpd to communicated via shared memory with
BridgeWays.  So we will fix selinux-policy.  It is arguable whether BridgeWays
tool should use shared memory rather then some easier to control interprocess
communications like namedpipes.

Comment 6 RHEL Product and Program Management 2007-10-16 03:54:06 UTC
This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release.  Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products.  This request is not yet committed for inclusion in an Update

Comment 7 Jay Turner 2007-11-30 07:30:45 UTC
QE ack for RHEL5.2.  Reproducer in comment 0.

Comment 9 Eduard Benes 2008-02-14 16:07:58 UTC
Manoj, could you please try the new policy available at the link below 
and reply whether the new packages solve your problem. The fix should be 
present in selinux-policy >= 2.4.6-104.
Thank you.


Comment 10 manoj 2008-02-15 11:03:17 UTC
This is not reproducible on RHEL5.1 system which comes with policy 104 by default.

Comment 13 errata-xmlrpc 2008-05-21 16:05:20 UTC
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.


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