RE: Managing SELinux in the Enterprise

[Douglas Brown]

Thanks to those who have replied. I’ve looked at the semanage python library that underpins the semanage tool, and created a hello world with it; as with anything Python, it’s straightforward.

Mandatory Access Controls have strong theoretical foundations in set theory and Python has native support for sets, so my idea is to create a tool called ‘secompliance’ that can be run by cron/puppet/etc to diff the running and expected config using set operators then resolve conflicts as appropriate. Naturally, if it comes off, I will provide it to the community.

Cheers,
Doug

From: [e-mail] [mailto:[e-mail]] On Behalf Of Jeremy Young
Sent: Monday, 13 October 2014 3:09 AM
To: Mark Montague
Cc: [e-mail]
Subject: Re: Managing SELinux in the Enterprise

I'll second the cron option.  If you're like me and have only recently gotten sign-off for a tool like Puppet or Ansible, scripts and crons will still work while you transition to the CM tool.  For example, I'll run this in cron.hourly to maintain a consistent state of the booleans available.  It may not be perfect, but it's a nice go-between until we can finish implementing Puppet.

#!/bin/bash
## Use lists in /etc/selinux to set SELinux booleans to desired state

PREFIX=/etc/selinux
LOGFILE=/var/log/sebooleans

touch ${LOGFILE}
for state in on off; do
            cat ${PREFIX}/booleans$state | while read variable; do
                ## getsebool is a lot faster than semanage for this task
                        if [[ "$( getsebool $variable | gawk '{print $3}' )" != "$state" ]]; then

## If we're running the script manually, output info to the screen
                                    if [[ -z "$PS1" ]]; then
                                                echo "Setting $variable to $state..."
                                    fi

echo "Setting $variable to $state at $( date +%c )..." >> ${LOGFILE}
                                    setsebool -P $variable $state
                        fi
            done
done

I like the idea of a hash comparison.  After the required action is taken, hash the relevant file and store it somewhere for reference later.  Have Puppet execute your script, first hashing the relevant file and comparing it to your known value from last time.  So, for your original question, the files modules/active/users.local and modules/active/seusers.final could provide you with the information that you'd want.

If that's no good, maybe you grep through these files to confirm the existence of your customizations, and for every one that is missing, append it to a temporary file, executing only the required commands with one semanage.

On Sun, Oct 12, 2014 at 9:49 AM, Mark Montague <[e-mail]> wrote:
On 2014-10-12 6:14, Douglas Brown wrote:
semanage is great for general administration but not for compliance; it's not really designed to compare an expected configuration with running configuration, and rectify any differences, rather, for the most part applies cumulative changes.

I use a cron job that runs "semanage -o" to dump the current configuration and compare it, using diff, with the expected configuration which is just the output of "semanage -o -" manually generated by an administrator at the last time the configuration was changed.

The same cronjob also checks the output of sestatus and "semodule -l" against expected values.

This approach is primitive, but it works.  You could hash the output, if you wanted, and compare the hash instead of using diff.  I use diff in order to have the cron job email the administrator the diff output, showing how the actual configuration is different from the expected configuration in the alert.

--

Mark Montague

[e-mail]

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Jeremy Young, M.S., RHCSA