System Administration and programming are becoming more and more entwined with each passing year. If you’re not programming yet (or don’t view the scripting/configuration-management you do as programming), my hunch is that you will be, soon.
There were a few talks at 32c3 about different methods for securing applications on Linux and Unix. You’ve probably heard of several, like AppArmor, SELinux. Capsicum is an interesting solution for FreeBSD; its basics are explained well in this video (although the video is really about another technology).
We’re definitely still at the very beginning stages of running untrusted code safely on our machines. It’s kludgy, breaks common applications, and works cleanly for only a few very specific use-cases at the moment. One of the problems is that applications really aren’t written with containment in mind — a lot of security problems require the cooperation of developers to really work smoothly. For example, your web browser needs to read and write files ANYWHERE on your filesystem (for opening local HTML and saving files from the Web). Even if web browsers had no other features, this would make them difficult to effectively contain.
CloudABI looks like it’s a big step forward in this space. It’s a way to limit what software can do once it’s running on your system; a sort of ‘restricted execution environment.’ CloudABI has three huge features, along with many great small ones):
- Capsicum is always turned on.
- Applications are forced to behave (no global namespaces, no hardcoded filepaths). Dependency injection is enforced.
- Implementations/Ports for NetBSD + Linux.
This talk gives you a good idea of how it works on both a theoretical and a practical level. Even if you never write applications that comply with an environment like CloudABI or mechanisms like Capsicum/SELinux/AppArmor/etc., this talk is an interesting introduction to the thoughts behind how to contain applications, write safer/less-exploitable applications, and otherwise improve Operating System security.