apparmor_monkeys 0.0.1

What does this do?

Imagine you’ve written a simple Django application. Maybe you just followed the Django tutorial. All your code does is a bit of database querying. Then you deploy it under AppArmor and:

type=AVC msg=audit(1443087838.797:1078): apparmor="DENIED" operation="exec" profile="helloworld-application" name="/bin/dash" pid=8202 comm="python" requested_mask="x" denied_mask="x" fsuid=999 ouid=0

Suddenly your audit log is full of messages complaining that your application is trying to run a shell. You certainly didn’t write code to do that. Whats going on? Did you get hacked?

You (probably ;)) didn’t get hacked.

Turns out python shells out when doing some fairly mundane stuff. Up until now you could:

• Ignore it. Let your audit log have DENIED entries that you have to ignore. Now it’s hard to spot suspicious behaviour in your monitoring. Thinks might be broken, thinks might not be broken. Hope you don’t have to go through that log with a security professional.

• Allow it. Now your profile is broader than it needs to be. You are throwing away the security you gain in the first place. Hope you don’t have to go through that profile with a security professional.

This package patches several stdlib API’s to avoid subprocess usage, letting you keep your simple profiles and clean audit logs.

sh -c "uname %s 2>%s"

Activating the monkey patches

from apparmor_monkeys import patch_modules
patch_modules()

import apparmor_monkeys; apparmor_monkeys.patch_modules()

Switching profiles

You can harden your AppArmor profiles further using change_profile to switch into a different profile after initialising your app.

If using multiprocess gunicorn (i.e. synchronous gunicorn) then you can wrap your workers in their own specific profile. In your gunicorn config you can add a hook to do this:

from apparmor_monkeys import change_profile

def post_fork(server, worker):
    change_profile("myapplication//worker")

You can do this for celery too:

from apparmor_monkeys import change_profile
from celery import signals

@signals.worker_process_init.connect
def switch_apparmor_profile(sender=None, signal=None):
    change_profile("tenselfservice-worker//worker")