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Bug 1446331 - SELinux is preventing munin-cgi-graph from altering munin_var_lib_t resources
Summary: SELinux is preventing munin-cgi-graph from altering munin_var_lib_t resources
Keywords:
Status: CLOSED WONTFIX
Alias: None
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: selinux-policy
Version: 6.9
Hardware: Unspecified
OS: Linux
unspecified
low
Target Milestone: rc
: ---
Assignee: Lukas Vrabec
QA Contact: BaseOS QE Security Team
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2017-04-27 16:57 UTC by tlum
Modified: 2017-10-02 13:25 UTC (History)
8 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2017-10-02 13:25:11 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)

Description tlum 2017-04-27 16:57:40 UTC 
Description of problem:

When accessing http://server.domain.tld/munin/static/dynazoom.html?..., SELinux is preventing creation and alteration of munin_var_lib_t tagged resources. The zoom functionality dynamically creates munin_var_lib_t tagged directory structures and graph resources, and is trying to do so with an scontext of httpd_munin_script_t. According to the active policy, only the munin_t scontext has the permissions necessary to carry out the operations that are being attempted.

I also question the need for an httpd script to be doing a dir setattr on /var/cache/fontconfig, but that's a separate issue.


Version-Release number of selected component (if applicable):
CentOS release 6.9 (Final)
Linux munsrvp01 2.6.32-696.1.1.el6.i686 #1 SMP Tue Apr 11 16:37:48 UTC 2017 i686 i686 i386 GNU/Linux
selinux-policy.noarch                       3.7.19-307.el6
selinux-policy-targeted.noarch              3.7.19-307.el6
munin.noarch                                2.0.33-1.el6
httpd.i686                                  2.2.15-59.el6.centos

shell> semanage module -l | grep munin
munin                    1.7.0

How reproducible:
Alwayse

Steps to Reproduce:
1. Install munin and httpd
2. Set graph_strategy cron in /etc/munin/munin.conf
3. Wait for the cronjob to generate the configuration
4. Navigate to a nodes resource graph
5. Click on the resource graph to visit it's "dynazoom" link
6. Click the query button to regenerate the graph

Actual results:

Browser: "Missing image" icon
/var/log/munin/munin-cgi-graph.log: RDD Errors
/var/log/audit/audit.log: Multiple AVC's


Expected results:

Browser: An actual graph image and no errors or AVCs logged


Additional info:

The specific AVCs:
type=AVC msg=audit(1493310701.341:29359): avc:  denied  { setattr } for  pid=7168 comm="munin-cgi-graph" name="fontconfig" dev=dm-0 ino=5791 scontext=system_u:system_r:httpd_munin_script_t:s0 tcontext=system_u:object_r:fonts_cache_t:s0 tclass=dir

type=SYSCALL msg=audit(1493310701.341:29359): arch=40000003 syscall=15 success=no exit=-1 a0=92cf430 a1=1ed a2=8e60c8 a3=92cf430 items=0 ppid=3679 pid=7168 auid=4294967295 uid=48 gid=48 euid=48 suid=48 fsuid=48 egid=48 sgid=48 fsgid=48 tty=(none) ses=4294967295 comm="munin-cgi-graph" exe="/usr/bin/perl" subj=system_u:system_r:httpd_munin_script_t:s0 key=(null)

<after a re-query>

type=AVC msg=audit(1493310940.408:29370): avc:  denied  { setattr } for  pid=7436 comm="munin-cgi-graph" name="fontconfig" dev=dm-0 ino=5791 scontext=system_u:system_r:httpd_munin_script_t:s0 tcontext=system_u:object_r:fonts_cache_t:s0 tclass=dir

type=AVC msg=audit(1493310940.766:29371): avc:  denied  { write } for  pid=7436 comm="munin-cgi-graph" name="diskstats_iops" dev=dm-0 ino=393138 scontext=system_u:system_r:httpd_munin_script_t:s0 tcontext=system_u:object_r:munin_var_lib_t:s0 tclass=dir

type=AVC msg=audit(1493310940.766:29371): avc:  denied  { add_name } for  pid=7436 comm="munin-cgi-graph" name="sda-pinpoint=1493166786,1493274786.png?&lower_limit=&upper_limit=&size_x=800&size_y=400" scontext=system_u:system_r:httpd_munin_script_t:s0 tcontext=system_u:object_r:munin_var_lib_t:s0 tclass=dir

type=AVC msg=audit(1493310940.766:29371): avc:  denied  { create } for  pid=7436 comm="munin-cgi-graph" name="sda-pinpoint=1493166786,1493274786.png?&lower_limit=&upper_limit=&size_x=800&size_y=400" scontext=system_u:system_r:httpd_munin_script_t:s0 tcontext=system_u:object_r:munin_var_lib_t:s0 tclass=file

type=AVC msg=audit(1493310940.766:29371): avc:  denied  { write } for  pid=7436 comm="munin-cgi-graph" name="sda-pinpoint=1493166786,1493274786.png?&lower_limit=&upper_limit=&size_x=800&size_y=400" dev=dm-0 ino=395491 scontext=system_u:system_r:httpd_munin_script_t:s0 tcontext=system_u:object_r:munin_var_lib_t:s0 tclass=file

type=AVC msg=audit(1493310941.087:29372): avc:  denied  { setattr } for  pid=7436 comm="munin-cgi-graph" name="sda-pinpoint=1493166786,1493274786.png?&lower_limit=&upper_limit=&size_x=800&size_y=400" dev=dm-0 ino=395491 scontext=system_u:system_r:httpd_munin_script_t:s0 tcontext=system_u:object_r:munin_var_lib_t:s0 tclass=file

type=AVC msg=audit(1493310941.091:29373): avc:  denied  { remove_name } for  pid=7436 comm="munin-cgi-graph" name="sda-pinpoint=1493166786,1493274786.png?&lower_limit=&upper_limit=&size_x=800&size_y=400" dev=dm-0 ino=395491 scontext=system_u:system_r:httpd_munin_script_t:s0 tcontext=system_u:object_r:munin_var_lib_t:s0 tclass=dir

type=AVC msg=audit(1493310941.091:29373): avc:  denied  { unlink } for  pid=7436 comm="munin-cgi-graph" name="sda-pinpoint=1493166786,1493274786.png?&lower_limit=&upper_limit=&size_x=800&size_y=400" dev=dm-0 ino=395491 scontext=system_u:system_r:httpd_munin_script_t:s0 tcontext=system_u:object_r:munin_var_lib_t:s0 tclass=file

audit2allow summarization of that mess:
#============= httpd_munin_script_t ==============
allow httpd_munin_script_t fonts_cache_t:dir setattr;
#!!!! The source type 'httpd_munin_script_t' can write to a 'dir' of the following types:
# httpd_munin_rw_content_t, munin_log_t, httpd_munin_script_tmp_t

allow httpd_munin_script_t munin_var_lib_t:dir { write remove_name add_name };
allow httpd_munin_script_t munin_var_lib_t:file { write create unlink setattr };

Dump of the relevant allow rules in munin.pp. The active policy implies that scontext httpd_munin_script_t is read_only and scontext munin_t is read_write, which conflicts with how scontext httpd_munin_script_t is being used:
shell> grep  'munin_var_lib_t\|fonts_cache_t' munin.sedismod.out
  allow munin_t munin_var_lib_t : [dir] { ioctl read write getattr lock add_name remove_name search open };
  allow munin_t munin_var_lib_t : [dir] { ioctl read write create getattr setattr lock unlink link rename add_name remove_name reparent search rmdir open };
  allow munin_t munin_var_lib_t : [dir] { ioctl read write getattr lock add_name remove_name search open };
  allow munin_t munin_var_lib_t : [file] { ioctl read write create getattr setattr lock append unlink link rename open };
  allow munin_t munin_var_lib_t : [dir] { ioctl read write getattr lock add_name remove_name search open };
  allow munin_t munin_var_lib_t : [lnk_file] { ioctl read write create getattr setattr lock append unlink link rename };
  allow munin_t [fonts_cache_t] : [dir] { ioctl read getattr lock search open };
  allow munin_t [fonts_cache_t] : [dir] { getattr search open };
  allow munin_t [fonts_cache_t] : [file] { ioctl read getattr lock open };
  allow munin_t [fonts_cache_t] : [dir] { getattr search open };
  allow munin_t [fonts_cache_t] : [lnk_file] { read getattr };
  allow munin_t [fonts_cache_t] : [dir] { setattr };
  allow munin_disk_plugin_t munin_var_lib_t : [dir] { getattr search open };
  allow munin_disk_plugin_t munin_var_lib_t : [file] { ioctl read write getattr lock append open };
  allow munin_mail_plugin_t munin_var_lib_t : [dir] { getattr search open };
  allow munin_mail_plugin_t munin_var_lib_t : [file] { ioctl read write getattr lock append open };
  allow munin_system_plugin_t munin_var_lib_t : [dir] { getattr search open };
  allow munin_system_plugin_t munin_var_lib_t : [file] { ioctl read write getattr lock append open };
  allow httpd_munin_script_t [fonts_cache_t] : [dir] { ioctl read getattr lock search open };
  allow httpd_munin_script_t [fonts_cache_t] : [dir] { getattr search open };
  allow httpd_munin_script_t [fonts_cache_t] : [file] { ioctl read getattr lock open };
  allow httpd_munin_script_t [fonts_cache_t] : [dir] { getattr search open };
  allow httpd_munin_script_t [fonts_cache_t] : [lnk_file] { read getattr };
  allow httpd_munin_script_t munin_var_lib_t : [dir] { getattr search open };
  allow httpd_munin_script_t munin_var_lib_t : [file] { ioctl read getattr lock open };
Comment 2 Lukas Vrabec 2017-10-02 13:25:11 UTC 
Red Hat Enterprise Linux 6 transitioned to the Production 3 Phase on May 10, 2017.  During the Production 3 Phase, Critical impact Security Advisories (RHSAs) and selected Urgent Priority Bug Fix Advisories (RHBAs) may be released as they become available.

The official life cycle policy can be reviewed here:
http://redhat.com/rhel/lifecycle

This issue does not appear to meet the inclusion criteria for the Production Phase 3 and will be marked as CLOSED/WONTFIX. If this remains a critical requirement, please contact Red Hat Customer Support to request a re-evaluation of the issue, citing a clear business justification.  Red Hat Customer Support can be contacted via the Red Hat Customer Portal at the following URL:

https://access.redhat.com
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