Bug 1390657

Summary: SELinux policy breaks rotation of chronyd logs
Product: Red Hat Enterprise Linux 6 Reporter: Pavel Kankovsky <peak>
Component: selinux-policyAssignee: Lukas Vrabec <lvrabec>
Status: CLOSED ERRATA QA Contact: Milos Malik <mmalik>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 6.9CC: dwalsh, lvrabec, mgrepl, mmalik, peak, plautrba, pvrabec, ssekidde
Target Milestone: rc   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: selinux-policy-3.7.19-297.el6 Doc Type: If docs needed, set a value
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Story Points: ---
Clone Of: Environment:
Last Closed: 2017-03-21 09:48:30 UTC Type: Bug
Regression: --- Mount Type: ---
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Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:

Description Pavel Kankovsky 2016-11-01 15:34:46 UTC
Description of problem:

SELinux does not allow logrotate to tell chronyd to reopen log files.

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

selinux-policy-targeted-3.7.19-292.el6.noarch
(also: chrony-2.1.1-1.el6.x86_64)

How reproducible:

Easily.

Steps to Reproduce:
1. Make sure SELinux is enabled and enforcing.
2. Install chrony.
3. Enable logging in /etc/chrony.conf (for instance, I wanted to enable the tracking log with "log tracking").
4. Wait.

Actual results:

logrotate renames the current log file but the invocation of "chronyc -a cyclelogs" in its postrotate scriptlet fails because chronyc is running as logrotate_t and logrotate_t is not allowed to read chronyd_keys_t files like /etc/chrony.keys. chronyd does not create a new log file and keeps writing to the old one.

Here is a sample record of the failure from audit.log:

type=AVC msg=audit(1477445821.779:19618): avc:  denied  { read } for  pid=11448 comm="chronyc" name="chrony.keys" dev=xvda1 ino=23521 scontext=system_u:system_r:logrotate_t:s0-s0:c0.c1023 tcontext=system_u:object_r:chronyd_keys_t:s0 tclass=file
type=SYSCALL msg=audit(1477445821.779:19618): arch=c000003e syscall=2 success=no exit=-13 a0=7ffeedc115e0 a1=0 a2=1b6 a3=0 items=0 ppid=11447 pid=11448 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=2307 comm="chronyc" exe="/usr/bin/chronyc" subj=system_u:system_r:logrotate_t:s0-s0:c0.c1023 key=(null)

Expected results:

chronyd closes the old log file, creates a new one and writes new log messages there.

Additional info:

Obviously, manual invocations of logrotate running as unconfined_t are not affected.

Comment 5 Milos Malik 2016-11-25 10:15:16 UTC
Could you re-run the scenario in enforcing mode after making the logrotate_t domain permissive?

# semanage permissive -a logrotate_t

So that we know if there are additional SELinux denials.

# ausearch -m avc -m user_avc -m selinux_err -m user_selinux_err -i -ts today

Comment 6 Pavel Kankovsky 2016-11-26 22:28:28 UTC
[root@xxxxx ~]# ausearch -m avc -m user_avc -m selinux_err -m user_selinux_err -i -ts today
----
type=SYSCALL msg=audit(11/26/2016 03:29:01.799:3867) : arch=x86_64 syscall=open success=yes exit=4 a0=0x7fff2ddd55a0 a1=O_RDONLY a2=0x1b6 a3=0x0 items=0 ppid=16372 pid=16373 auid=root uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=(none) ses=592 comm=chronyc exe=/usr/bin/chronyc subj=system_u:system_r:logrotate_t:s0-s0:c0.c1023 key=(null) 
type=AVC msg=audit(11/26/2016 03:29:01.799:3867) : avc:  denied  { open } for  pid=16373 comm=chronyc name=chrony.keys dev=xvda1 ino=23521 scontext=system_u:system_r:logrotate_t:s0-s0:c0.c1023 tcontext=system_u:object_r:chronyd_keys_t:s0 tclass=file 
type=AVC msg=audit(11/26/2016 03:29:01.799:3867) : avc:  denied  { read } for  pid=16373 comm=chronyc name=chrony.keys dev=xvda1 ino=23521 scontext=system_u:system_r:logrotate_t:s0-s0:c0.c1023 tcontext=system_u:object_r:chronyd_keys_t:s0 tclass=file 
----
type=SYSCALL msg=audit(11/26/2016 03:29:01.799:3868) : arch=x86_64 syscall=fstat success=yes exit=0 a0=0x4 a1=0x7fff2ddd5400 a2=0x7fff2ddd5400 a3=0x0 items=0 ppid=16372 pid=16373 auid=root uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=(none) ses=592 comm=chronyc exe=/usr/bin/chronyc subj=system_u:system_r:logrotate_t:s0-s0:c0.c1023 key=(null) 
type=AVC msg=audit(11/26/2016 03:29:01.799:3868) : avc:  denied  { getattr } for  pid=16373 comm=chronyc path=/etc/chrony.keys dev=xvda1 ino=23521 scontext=system_u:system_r:logrotate_t:s0-s0:c0.c1023 tcontext=system_u:object_r:chronyd_keys_t:s0 tclass=file

Comment 9 errata-xmlrpc 2017-03-21 09:48:30 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.

https://rhn.redhat.com/errata/RHBA-2017-0627.html