Re: AppArmor FAQ

From: Joshua Brindle
Date: Tue Apr 24 2007 - 21:04:15 EST

Crispin Cowan wrote:
David Wagner wrote:
James Morris wrote:
[...] you can change the behavior of the application and then bypass policy entirely by utilizing any mechanism other than direct filesystem access: IPC, shared memory, Unix domain sockets, local IP networking, remote networking etc.
Just look at their code and their own description of AppArmor.
My gosh, you're right. What the heck? With all due respect to the
developers of AppArmor, I can't help thinking that that's pretty lame.
I think this raises substantial questions about the value of AppArmor.
What is the point of having a jail if it leaves gaping holes that
malicious code could use to escape?

And why isn't this documented clearly, with the implications fully

I would like to hear the AppArmor developers defend this design decision.
It was a simplicity trade off at the time, when AppArmor was mostly
aimed at servers, and there was no HAL or DBUS. Now it is definitely a
limitation that we are addressing. We are working on a mediation system
for what kind of IPC a confined process can do

Also, things like:

share_mem /usr/bin/firefox r, # /bin/foo can share memory with /usr/bin/firefox for read only

clearly show that you aren't using native abstractions for IPC. The native abstraction for shared memory would be the key used when creating the shared memory segment. The same goes for message queues which are noticeably missing from the "simplified" IPC model.

This, of course, begs the question of whether you are using native abstractions for profiles at all, processes have nothing to do with the binary they started from after they've been started. The binary on disk could be something entirely different than the process from which it ran.
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