Bug 1122866

Summary:	debug log has "Unable to change mtime of "/etc/krb5.conf" [13]: Permission denied" on sssd startup
Product:	Red Hat Enterprise Linux 6	Reporter:	Kaushik Banerjee <kbanerje>
Component:	selinux-policy	Assignee:	Miroslav Grepl <mgrepl>
Status:	CLOSED ERRATA	QA Contact:	Milos Malik <mmalik>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	6.6	CC:	dpal, dwalsh, grajaiya, jgalipea, jhrozek, lslebodn, lvrabec, mgrepl, mkosek, mmalik, nalin, pbrezina, preichl, rmainz, tlavigne
Target Milestone:	rc
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	selinux-policy-3.7.19-253.el6	Doc Type:	Bug Fix
Doc Text:	Cause: Starting/Restarting sssd. Consequence: sssd daemon cannot write to krb5 config file. Fix: Add selinux rule that sssd daemon can write to krb5 config file. Result: Now sssd daemon can write to krb5 config file.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2014-10-14 08:03:44 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Kaushik Banerjee 2014-07-24 09:07:56 UTC

Description of problem:
debug log has "Unable to change mtime of "/etc/krb5.conf" [13]: Permission denied" on sssd restart

Version-Release number of selected component (if applicable):
sssd-1.11.6-4.el6
selinux-policy-3.7.19-245.el6

How reproducible:
Always

Steps to Reproduce:
1. Make sure selinux is in enforcing mode
2. Join client to AD Server using "net join"
3. Configure sssd to use ad provider
4. Start/restart sssd

Actual results:

Domain log shows:

(Thu Jul 24 04:41:36 2014) [sssd[be[sssdad2012.com]]] [sss_write_domain_mappings] (0x0200): Mapping file for domain [sssdad2012.com] is [/var/lib/sss/pubconf/krb5.include.d/domain_realm_sssdad2012_com]
(Thu Jul 24 04:41:36 2014) [sssd[be[sssdad2012.com]]] [sss_krb5_touch_config] (0x0020): Unable to change mtime of "/etc/krb5.conf" [13]: Permission denied
(Thu Jul 24 04:41:36 2014) [sssd[be[sssdad2012.com]]] [sss_write_domain_mappings] (0x0020): Unable to change last modification time of krb5.conf. Created mappings may not be loaded.


Expected results:


Additional info:
Setting selinux to permissive doesn't show this message on sssd restart. But I don't any AVCs being generated.

Comment 2 Nalin Dahyabhai 2014-07-24 12:47:17 UTC

Can you run "semodule -DB" to tweak your system's policy to disable "dontaudit" rules, and see if denials start getting logged?

Comment 3 Kaushik Banerjee 2014-07-24 13:29:41 UTC

Thanks Nalin,

I now see the following avc:
type=AVC msg=audit(1406208380.958:67773): avc:  denied  { write } for  pid=14763 comm="sssd_be" name="krb5.conf" dev=dm-0 ino=6329 scontext=unconfined_u:system_r:sssd_t:s0 tcontext=system_u:object_r:krb5_conf_t:s0 tclass=file

Comment 4 Jakub Hrozek 2014-07-24 13:37:38 UTC

Cool, I didn't know about semodul -DB.

Per comment #3, moving to selinux-policy. We need the sssd_be process to be able to touch the krb5.conf, similar to what we allow on el7.

Comment 5 Miroslav Grepl 2014-07-25 10:02:43 UTC

Yes we dontaudit this rule

#============= sssd_t ==============

#!!!! This avc has a dontaudit rule in the current policy
allow sssd_t krb5_conf_t:file write;

Comment 6 Miroslav Grepl 2014-07-25 10:04:04 UTC

Also we don't allow it in RHEl7/Fedora.


$ sesearch -A -s sssd_t -t krb5_conf_t
Found 2 semantic av rules:
   allow nsswitch_domain krb5_conf_t : file { ioctl read getattr lock open } ; 
   allow nsswitch_domain krb5_conf_t : dir { getattr search open } ;

Comment 7 Jakub Hrozek 2014-07-31 12:55:08 UTC

(In reply to Miroslav Grepl from comment #6)
> Also we don't allow it in RHEl7/Fedora.
> 
> 
> $ sesearch -A -s sssd_t -t krb5_conf_t
> Found 2 semantic av rules:
>    allow nsswitch_domain krb5_conf_t : file { ioctl read getattr lock open }
> ; 
>    allow nsswitch_domain krb5_conf_t : dir { getattr search open } ;

Yes, we should also allow sssd to "touch" krb5.conf in RHEL-7 and Fedora.

Comment 8 Kaushik Banerjee 2014-08-28 09:39:11 UTC

Any update? Can we get it fixed in RHEL6.6?

Comment 9 Miroslav Grepl 2014-09-01 11:11:01 UTC

commit b71fe9935e0d39152304dbf4104e302ccec46e82
Author: Miroslav Grepl <mgrepl>
Date:   Thu Aug 28 15:04:22 2014 +0200

    sssd needs to be able write krb5.conf

Comment 12 errata-xmlrpc 2014-10-14 08:03:44 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.

http://rhn.redhat.com/errata/RHBA-2014-1568.html