How to debug SE linux errors, and write custom policies

Reading time ~1 minute

Sometimes, you find yourself trying to debug a problem with SE linux, specially during software development, or packaging new software features. I have found this with neutron agents to happen quite often, as new system interactions are developed. Disabling selinux during development is generally a bad idea, because you’ll discover such problems later in time and under higher pressure (release deadlines). Here we show a recipe, from Kashyap Chamarthy, to find out what rules are missing, and generate a possible SELinux policy:

Make sure selinux is enabled

sudo su -
setenforce 1

Clear your audit log, and supposing the problem was in neutron-dhcp-agent, restart it.

 > /var/log/audit/audit.log
systemctl restart neutron-dhcp-agent

Wait for the problem to be reproduced..

Find what you got, and create a reference policy

cat /var/log/audit/audit.log
cat /var/log/audit/audit.log | audit2allow -R

At that point, report a bug so you get those policies incorporated in advance. Give a good description of what’s blocked by the policies, and why does it need to be unblocked. Now you can generate a policy, and install it locally:

You can generate a SELinux loadable module to move on without disabling the whole SELinux:

cat /var/log/audit/audit.log | audit2allow -a -M neutron

And you can also install it in runtime

semodule -i neutron.pp

Restart neutron-dhcp-agent (or re-trigger the problem to make sure it’s fixed)

systemctl restart neutron-dhcp-agent

Cirros Image mirror

Every time I try to download a cirros image from[cirros cloud](http://download.cirros-cloud.net/0.4.0/) for use in myOpenStack devel envi...… Continue reading

Neutron external network with routing (no NAT)

Published on January 10, 2018

We moved again! hello jekyll, bye tumblr

Published on January 03, 2018