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#bsdcan

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New @bsdcan Video Posted:

ABI stability in FreeBSD By ShengYi Hung

youtu.be/vzU6vKd1OFM

The FreeBSD project doesn't guarantee the ABI stability in major version. However, for the minor version, we also not fully guarantee. This cause maintaining a out-of-tree module (at least for Kernel module like VirtualBox) a big problem because module compiles from 14.0 may not able to use at 14.1. This also cause some problem when distributing modules with freshpkg in our base because our pkg system only support build for all major version.

A wiki page distribute the workflow of CTF diff and script:

wiki.freebsd.org/ShengYiHong/A

The outline of my slides will be as following:

What is ABI and why we needs to stablize ABI?

How to maintain ABI stability (a tool to check and ABI tag in binary)?

ABI information (CTF and dwarf) in elf and why we use CTF?

New tools CTFDiff: Why implement new CTFDiff and don't use the illumos one? (we port libctf and other command line tools like ctfdump to FreeBSD from illumos)

CTFDiff script: scripts download tarball from web (kernel tarball) so that we can compare abi between local compile one and web.

Short demo (maybe) for ctfdiff ?

Current status of CTFDiff (needs reviewers, licenses issue (CDDL))

Future works: regulize a stable function/obj ABI/API in kernel.

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New @bsdcan video posted:

Controlled credentials transitions without privileges: mac_do(4), mdo(1) and setcred(2) by Olivier Certner

youtu.be/Wl2hewfxcKM

In this talk, we will present a project that aims at allowing controlled process credentials transitions without using setuid executables but instead leveraging FreeBSD's MAC framework.

Traditional credentials-changing programs, such as sudo(8), have a non-negligible attack surface as they often include a lot of infrequently used features and mechanisms that can be dangerous from a security standpoint (e.g., loadable modules). As these programs have to run as 'root', compromising them can have catastrophic consequences.

The mac_do(4) kernel module has been introduced to allow unprivileged processes to change credentials, provided the requested changes are explicitly allowed by rules set by an administrator. It has recently undergone major changes. First, thanks to a redesign of rules, it is now possible to specify full sets of user and group IDs that must be present or absent in the final credentials for a transition to be accepted. Second, each jail can be configured with a different set of rules, allowing different transitions to be allowed as needed, or to inherit from the parent jail.

We will describe how mac_do(4)'s credentials rules work, what the role of the mdo(1) companion program is, and what you can do with them in practice.

We will also touch on some aspects of the implementation, notably why we needed to introduce the new setcred(2) system call, which allows to change all process credentials in a single call, and possibly those that are related to the use of some FreeBSD's kernel sub-systems (notably, sysctl, jails and OSD).

While the current implementation is of production quality and immediately useful, there are lots of possible ways to extend it to cover more scenarios and to progress towards our ideal of having all credentials-changing programs work without the setuid bit. We will present them in the hope to get feedbacks.

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BSDCan 2025 Keynote: Hardware Support for Memory Hungry Applications by Margo Seltzer

youtu.be/OCWaGRcPO8E?feature=s

For nearly 60 years, we lived in a CPU-centric universe. Today, we are on the brink of a transition -- GPUs are the new golden child and those children demand unprecedented amounts of DRAM to satisfy modern data-hungry applications. I'm going to talk about these hardware trends and what they mean for those of us who build systems.
Speaker bio: Margo Seltzer is Canada 150 Research Chair in Computer Systems and the Cheriton Family chair in Computer Science at the University of British Columbia. Her research interests are in systems, construed quite broadly: systems for capturing and accessing data provenance, file systems, databases, transaction processing systems, storage and analysis of graph-structured data, and systems for constructing optimal and interpretable machine learning models.
She is the author of several widely-used software packages including database and transaction libraries and the 4.4BSD log-structured file system. Dr. Seltzer was a co-founder and CTO of Sleepycat Software, the makers of Berkeley DB, the recipient of the 2021 ACM Software Sytems award and the 2020 ACM SIGMOD Systems Award. She is a past President of the USENIX Assocation and served as the USENIX representative to the Computing Research Association Board of Directors. In 2019 recipient of the USENIX Lifetime Achievement Award.
For more information, please visit:
bsdcan.org/2025/

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As soon as I got confirmation that my presentation was accepted at #BSDCan, I started following Ottawa's weather forecasts from #FediMeteo. It was still cold then, and the temperatures looked frigid! Even though I've been back home for a while now, I still keep an eye on the forecasts. That city and the whole #BSDCan experience left such a positive and beautiful impression on me.
So, every time I get a notification and see the forecast, I relive a bit of those moments.

I cleaned a few things up on my compositor and wrote up install instructions for #OpenBSD if anyone was curious after my #BSDCan talk:

git.sr.ht/~phaedrus/Xuake

If you do try to get it working, let me know. If you are an international user and want the keyboard layout to be configurable, then especially let me know; that will jump that to top priority. (And writing that sentence might get it updated this week, anyway.)

YOU!

The @bsdtv BSD A/V Team in conjunction with @bsdcan and @EuroBSDCon could use YOUR HELP with:

1. Locating official project slide templates
2. Validating them for readability on a projector and for the visually limited (I hear there are fonts that are dyslexia-friendy)
3. Integrating best practices into semi-official event slides for those presenters who simply want "insert content here"
No, I did not say required.

Thank you!

"Where have you been for the last 20 years?" - The question that changed everything. This isn't a BSDCan report, but a personal reflection on how impostor syndrome stole decades from me, and why it's never too late to find your community and live life fully.

my-notes.dragas.net/2025/06/17

my-notes.dragas.netWhere Have You Been for the Last 20 Years? | MyNotes
More from Stefano Marinelli
Continued thread

To make up for not searching it on the way to #BSDCan, CATSA searched the bag with the Positron. I guess swapping the filament into the other bag and adding dirty laundry was too tempting. Fortunately nothing seems to be missing, althougj I didn't count the socks.
@BugZ