Why Blu-Ray scares me

Now that Blu-Ray has all but won the HD format war I guess its a little late to post this but oh well, I’ll do it anyway.

Disclaimer: I am an HDDVD owner but this post is not a result of bitterness about my chosen format losing. The reason I’m posting here about (among others) is the actual reason I chose HDDVD. I also don’t want to talk about the pro’s and con’s of DRM or whether the DRM has been cracked and is accessible via other means. I am going to talk about the intentions of the format producers and what it means to consumers.

Misunderstanding UNIX security

I just got a comment on my post about path based access control that was fairly startling to me. The more I thought about it, though, the more I thought maybe others shared the beliefs so I’m going to respond to it here. inode-based security has analogous problems to path-based security. Software opens paths, not inodes, so it very much matters what the permissions are for the file at /etc/shadow or /var/data/mydb, regardless of what the inode happens to be.

Secure Networking with SELinux

During the last year quite a bit of effort has gone into improving SELinux’ networking support, thanks to the great SELinux community. While this support is still evolving it will be very beneficial for people to try it out and give feedback so the final result is useful to more users and meets the security needs of a wider audience. As the network support in SELinux continues to evolve (there are already other ideas being discussed for possible inclusion) I’ll try to keep this post updated so that people who find it will have the latest information available.

Don't disable SELinux!

A while back I wrote a post on companies telling their customers to disable SELinux in order to get applications running and why this is a very bad thing. While I don’t see the situation getting better in the near term I did see a blog posting today from an SAP employee about using SELinux with SAP. This made me happy Since I don’t think his blog software uses trackbacks I’ll be contacting him to suggest some changes.

SELinux training

My employer, Tresys Technology, occasionally hosts an SELinux training class, many of which I’ve been the teacher for. The course outline and slides are available for free at http://tresys.com/selinux/selinux-course-outline.html but that isn’t what this post is about. I’ve been asked if I think many people would pay to take an online shorter version of the class if it were around $500. I wasn’t sure how to answer so I decided to ask the people that read my blog what they think.

The Future of SELinux (or how we are going to take over the world)

I’ve been talking to a few people about what SELinux might look like in a few years and the conversations have been fairly stimulating so I’m going to share some of the ideas here.

As you (hopefully) know in my day job I work on the SELinux policy server, which as far as I know, is the most forward looking SELinux project around. Granted all those forward looking goals aren’t published on the site, hopefully we can remedy that at some point.. So alot of this is going to be centered around the policy server, other parts are just on my wishlist.. without further ado lets get started…

On AppArmor

This will be the last thing I write about AppArmor because quite honestly it’s a waste of time to constantly refute people and I’d rather work to make security better for everyone :) .

That said, I taught an SELinux tutorial at LWE San Francisco last week, unfortunately my tutorial wasn’t one of the ones reviewed by the media, what a shame. During the tutorial I was asked about AppArmor, to which I said they could come up after the tutorial to talk about it, I didn’t want to disparage it in front of an audience of 50, I’m a nice guy like that. :)

Then I saw this article, which has a quite humorous title, which prompted me to go ahead and write up something that I can point to in the future.

SELinux Policy Module Primer

Its been a while since my last post, I apologize but I have a good reason I promise :) . I’ve been busy working on a series of patches to make the SELinux policy compiler and libraries much more stable and robust and to make optional blocks in the base policy work correctly. While the libraries and compiler are fresh on my mind I thought I’d go ahead and write an article on how the SELinux policy modules work.

Trusted what?

This is a response to an open letter from Darren Moffat to IBM. While this open letter has very little substance and is almost entirely opinion there are some things I’d like to address.

Software not working? Disable SELinux.

So, this is a break from my normal philosophical theme to talk about a real experience I had this week.

Basically I was trying out some software, without saying what it was or who makes it, I thought it might be helpful for the software development I do at work. For those who don't know I work on SELinux libraries and the policy toolchain at work.

That said, I downloaded the trial version of the software and got to work. The first time I ran it I got a very obscure error, it had to do with how the app was being run (after installing it according to the instructions included). After figuring out the “correct” way to run it I started it up only to get another (more obscure) error. I emailed the support address found on their page, including strace outputs and a description of what happened with both issues.

I got an email from who I originally thought was a low level support staffer who was instructed to say this, but is actually a cofounder of the company. The email read:

Hi Joshua,

I think you may have selinux enabled (FC5 has this by default).

If /etc/selinux/config has the line:


then you need to change it to:


(or permissive should work, although I’ve not tried it).

Unfortunately, you need to reboot for the changes to take effect.

Hope this works for you (if not, please don’t hesitate to ask).