OpenBSD Journal

n2k16 hackathon report: guenther@ on RELRO support in binutils and arch specific cleanup

Contributed by nayden on from the (XOR) cookies and pilsner dept.

Our next report comes from Philip Guenther, who writes,

I don't actually do much hacking in the network stack. I've done some fixes and cleanup in the syscall/ioctl layers, but otherwise I stay out of sys/net*, so what was I doing at n2k16?

First idea was to get my CuBox-i installed and working. With a "well, duh" hint from krw@, I got it installed and working before I even left for Prague.

Uh, oops?

Once I had that, the next step was to do some arch-specific cleanup and improvements in libc,including eliminating unnecessary use of the PLT and implementing setjmp XOR-cookies. The CuBox is small enough that I actually put it in my check luggage and then hacked on it on my flight over the Atlantic. Intial diffs went out on the first day of the hackathon and by day three these bits were ready to be committed once the tree was unlocked.

So what next? How about a day hike with Theo and friends, catching a train to Karlštejn then looping out to Svatý Jan Pod Sklou and back to Srbsko to catch the train back? The weather was perfect, the company enjoyable, and the terrain and views interesting.

Back at the hackroom, I then spent the rest of the week on a larger project I had started back in late May: enabling the "relro" support in bintuils. I had gotten this working on amd64 and i386 in June, so I used this time to make it work on arm and study the situation on some other archs, as well as cleaning up some corners in This work has finally been committed; I hope to do a longer writeup on what this was about sooner rather than later.

There were of course conversations with others on various topics, including helping claudio@ understand the two types of session tickets in TLS and how they're handled in OpenSSL/LibreSSL and reviewing format fixes from benno@. I think I even got dragged into a networking discussion on some point.

Finally, on the last day I managed to find the right cobblestone to add to my collection, so the trip was a success.

Prague was beautiful, the fresh pilsner was tasty and refreshing, and the hackathon was well setup and stocked with all we needed. Many thanks to Sashan for organizing this and even picking me up at the airport when I arrived a day early!

Thanks for all the hard work and nice report Philip! The RELRO work has since landed in -current.

(Comments are closed)

  1. By Anonymous Coward ( on

    Thanks for all the great work and the nice writeup! :-)


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