watson.org · Domains · Slashdot Mirror

Re:Yeah by TheRaven64 · 2013-12-15 21:59 · Score: 4, Interesting · on Theo De Raadt Says FreeBSD Is Just Catching Up On Security

I have a lot of respect for most of the OpenBSD team, but Theo is definitely trolling here.

Let's start with the premise of TFA, which cites the article on Ars that was covered here a few days ago and was complete nonsense about the new random number infrastructure in FreeBSD. We are not moving away from using the hardware random number generator directly, we have never used the hardware random number generator. The new code that the Ars article was talking about is to allow the PRNG to be easily switched. In 10 we're shipping both Fortuna and Yarrow and the infrastructure allows more to be added. The code has been reviewed by two cryptographers that I know of and possibly others. Neither the old nor the new implementation is vulnerable to the attack against random number generators that was published a couple of months ago (Linux was the subject of the paper, not sure if OpenBSD was vulnerable).

If Theo is going to make such remarks as this, he should think more carefully first:

"Basically, it is 10 years of FreeBSD stupidity. They don't know a thing about security. They even ignore relevant research in all fields, not just from us, but from everyone."

He'd be advised to take a look at the transactions for the IEEE Symposium on Security and Privacy over the last 10 years and see how many papers are describing techniques that were both originally implemented on FreeBSD and are now part of the default install. Let's take a look at the two systems, from a security perspective. Both FreeBSD use SSP and non-excutable stack by default, so I'll skip those. To begin with, OpenBSD features missing on FreeBSD:

W^X enforcement. Definitely a nice idea, but it breaks some things (JITs mostly). The default memory map in FreeBSD is W^X, but it is possible to explicitly mmap() memory both writeable and executable. It's generally considered a bad idea though, and we don't ship any code that allows it. We permit third-party code to shoot itself in the foot if it really wants to and provide mitigation techniques to reduce the risk.

Then there's ASLR. This is a pretty nice technique, which is currently not implemented on FreeBSD. We do support PIE, so it would not be a horrendously difficult thing to add, but current implementations (including OpenBSD) use a surprisingly small amount of entropy in the address layout and so don't provide as much mitigation as you'd hope (which, of course, Theo knows, because he's very familiar with 'relevant research'). This is especially true on 32-bit systems.

And that's it for OpenBSD. Well, unless you want to count , but since that's vulnerable to a timing attack (still not fixed), which was published in the USENIX Workshop on Offensive Technologies, and Theo is aware of all 'relevant research' in security then it can't really still be there.

Now let's look at FreeBSD security mechanisms:

First up, jails. Jails are somewhere between a chroot and a VM: a shared kernel, but all of the global namespaces (filesystems, IP addresses, users) are separated and so you can completely isolate a service, such as a web browser, from the rest of the system. Scripts like ez-jail in the ports tree make it easy to set up lightweight service jails.

Then there's the MAC framework, which allows modular access control policies. This is used by a couple of FreeBSD derivatives: JunOS uses it to implement code signing, OS X and iOS use it for application sandboxing. You can also use it for traditional type enforcement policies, as in SELinux and a variety of other things.

And then there's Capsicum, which adds a capability model on top