It is also a testament to solid engineering and attention to good security practices in general. These still work, also against fancy new AI attackers.
When sophisticated attacks become cheaper to run, maybe it will (finally) be cheaper to do more solid engineering instead of doing it quick and dirty and ending up in indefinite bug-squashing mode.
How does this change the point that is being made in the article? Your agent is also only taking one of the existing roles that humans today occupy (e.g. the software operator or developer)
Varlink is based on much more conventional UNIX technology than Dbus, which is decades old: You connect to a named UNIX socket through its socket file in the filesystem (man page: unix(7)).
This is an old mechanism and it is known to work well. It does not require a broker service, it works right at system startup, and it does not require a working user database for permission checks (which would be a circular dependency for systemd in some configurations). If at all, I am surprised that systemd didn't use that earlier.
The main thing that Varlink standardizes on top of that is a JSON-based serialization format for a series of request/response pairs. But that seems like a lightweight addition.
It also does not require kernel support to work, the kernel support is already there. He mentioned in the talk that he'd like to be able to "tag" UNIX sockets that speak varlink as such, with kernel support. But that is not a prerequisite to use this at all. The service discovery -- and he said that in the talk as well -- is simply done by listing socket files in the file system, and by having a convention for where they are created.
Etoile had its own Smalltalk dialect back in the day, Pragmatic Smalltalk. This was a Smalltalk based on the Objective-C runtime, based on an OMeta implementation and a LLVM backend. David Chisnall, who created it at the time, ended up getting involved more in LLVM in the long run, I believe.
Absolutely, seccomp is also an unprivileged sandboxing mechanism in Linux. It does have the drawback however that the policies are defined in terms of system call numbers and their (register value) arguments, which complicates things, as it is a moving target.
FWIW, the additional ceremony in Linux is because Linux guarantees full ABI backwards compatibility (whereas in OpenBSD policy, compiled programs may need recompilation occasionally).
Similarly terse APIs as for Go and Rust are possible in C as well though, as wrapper libraries.
For full disclosure, I am the author of the go-landlock library and contributor to Landlock in the kernel.
The way I interpreted most of these "subclassing" cases in the GoF diagrams was actually as "subtyping", and then it makes more sense.
Regarding no one having a lock on the term "delegation", I think this is spot on. Yes, someone might have used the term differently before GoF, but that does not mean that GoF was wrong. It just meant something else in their context.
(Btw, congratulations, your comment is the first one so far in this comment thread that actually discusses the linked article and not just the GoF book itself.)
A rough description of upcoming network restriction features in Landlock and how they map to the BSD socket API is in the talk at https://youtu.be/K2onopkMhuM?start=2025 starting around 33:45
I really hope we can get back to these features soon :) I think these would be very useful.
Awesome! I'm happy to hear that you and others are interested in the configuration language. We should probably coordinate that on the Landlock mailing list when the time comes, so that we don't duplicate that work. We are open to outside contributions :)
OpenBSD did get it right, but they also have a more relaxed scheme for backwards compatibility across releases. Linux's strict ABI compatibility guarantees complicate matters slightly, but with the right supporting library it becomes tolerable.
(Full disclosure, I am the author of that library)
FWIW, I do hope that we can motivate people to use Landlock in the same way as people use pledge on OpenBSD, as a lightweight self-sandboxing mechanism that requires fewer architectural changes to your program and results in more constrained sandboxes than Linux namespaces and other mechanisms do.
Namespaces can also be used for sandboxing, but they have a series of problems. Most importantly, they require more substantial changes to your program that wants to sandbox itself, and the program has to jump through a series of hoops to get everything into the right state. It is possible, but the resulting program environment is in the end more unusual and the mechanisms for enabling unprivileged namespaces are making it difficult to use it for smaller use cases. (It involves re-execution of the program that wants to sandbox itself, whereas with Landlock, a small program can just install a Landlock policy during an early startup phase and continue with that.)
Controlling the rules through a separate process is not currently possible, but it was proposed earlier this month on the kernel mailing lists:
It takes very little resources on my Raspberry Pi and is built to be extensible and safe through its transparent way of storing wiki pages as markdown files.
I find this an offensive comment. The GIGO principle applies to documentation, and we would be in a much worse place if we didn't have the man page documentation written and reviewed by humans.