Re: SMACK netfilter smacklabel socket match

From: Tilman Baumann
Date: Mon Sep 29 2008 - 12:21:34 EST




Casey Schaufler wrote:
Tilman Baumann wrote:

Hmm. It looks as if your code will do what you're asking it to do.
Are you going to be happy with the access restrictions that will be
imposed by Smack?

I helped myself with rules like this.
_ foo rwx
But i wanted to add some security stuff like selinux for years,
and SMACK seems to be just great.
So i will spend some time making security rules after i got this routing
stuff to work. :)

I confess that I'm still not completely sure what you're up too,
but you might want to look at smackpolyport (it's in the smack-util
tarball) and might make your life easier if you want to have a
single server (running at foo) that deals with connections from
processes with multiple labels.

I'm essentially using this as some kind of iptables owner-match on steroids.
Owner match allows to filter on the processes uid, gid, and some other process attributes.
Unfortunately owner match is pretty much useless because of it's limited matching capabilities.

I'm really just abusing the way how security contexts of processes are transfered to all it's sockets.
This way I can label a process with a specific label which then gets transfered to all of it's sockets.
With this match I can look at the label via the socket of any packet in iptables.
I'm pretty much ignoring the Security aspect of SMACK right now and just use it as some label that I can stick to processes.

What I then to is write iptables OUTPUT chain matches which match for any of these labels and set some connection marks and firewall marks.
Which I then can use in routing rules to give different routing rules to specific processes. (Like all proxy traffic over a second DSL line)

I know, it's totally crazy. But it seems to work. :)
I just hope the security part of this all will not break anything. But it does not look like it would right now.

--
Tilman Baumann
Software Developer
Collax GmbH . Boetzinger Strasse 60 . 79111 Freiburg . Germany

p: +49 (0) 89-990157-0
f: +49 (0) 89-990157-11

Geschaeftsfuehrer: William K. Hite / Boris Nalbach
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