[ijustlovemath]

I've found it interesting that systemd and Linux user permissions/groups never come into the sandboxing discussions. They're both quite robust, offer a good deal of customization in concert,and by their nature, are fairly low cost.

[nextaccountic]

Unix permissions were written at a time where the (multi user) system was protecting itself from the user. Every program ran at the same privileges of the user, because it wasn't a security consideration that maybe the program doesn't do what the user thinks it does. That's why in the list of classic Unix tools there is nothing to sandbox programs or anything like that, it was a non issue

And today this is.. not sufficient. What we require today is to run software protected from each other. For quite some time I tried to use Unix permissions for this (one user per application I run), but it's totally unworkable. You need a capabilities model, not an user permission model

Anyway I already linked this elsewhere in this thread but in this comment it's a better fit https://xkcd.com/1200/

[nesarkvechnep]

There's FreeBSD's Capsicum. It's a full-blown sandboxing mode and capability framework. Unfortunately, Linux didn't adopt it and chose chaos.

[fsflover]

This is why my daily driver is https://qubes-os.org

[curt15]

>And today this is.. not sufficient. What we require today is to run software protected from each other. For quite some time I tried to use Unix permissions for this (one user per application I run), but it's totally unworkable. You need a capabilities model, not an user permission model

Unix permissions remain a fundamental building block of Android's sandbox. Each app runs as its own unix user.

[theteapot]

I feel like apparmor is getting there, very, very slowly. Just need every package to come with a declarative profile or fallback to a strict default profile.

[mike_hearn]

Yes but systemd is a full blown sandboxing system, and he said the two working in concert.

[moezd]

This assumes people know more than just writing Dockerfiles and push straight to production. This is still a rarity.

[ijustlovemath]

Nowadays, it's fairly simple to ask for a unit file and accompanying bash script/tests for correctness. I think the barrier in that sense has practically vanished.

[vbezhenar]

Linux kernel is ridden with local privilege escalation vulnerabilities. This approach works for trusted software that you just want to contain, but it won't work for malicious software.

[viraptor]

Ridden? There are issues from time to time, but it's not like you can grab the latest, patched Ubuntu LTS and escalate from an unprivileged seccomp sandbox that doesn't include crazy device files.

[realityfactchex]

> user permissions/groups never come into the sandboxing discussions

Sometimes *nix user accounts for AI agent sandboxing does come up in discussions. At [0], HN user netcoyote linked to his sandvault tool [1], which "sandboxes AI agents in a MacOS limited user account".

Actually seems like a great idea IMO, to be lightweight, generic, and robust-enough.

[0] https://news.ycombinator.com/item?id=46760777

[1] https://github.com/webcoyote/sandvault

[srcreigh]

It shouldn’t come up because it’s not sufficient. How would systemd prevent local JavaScript code from sending DNS, http, webrtc network requests when it’s opened in the users browser?

[pjmlp]

Because that is actually UNIX user permissions/groups, with a long history of what works, and what doesn't?

[ape4]

cgroups are part of whats used to implement docker and podman

[ijustlovemath]

True, and they do indeed offer an additional layer of protection (but with some nontrivial costs). All (non-business killing) avenues should be used in pursuit of defense in depth when it comes to sandboxing. You could even throw a flatpak or firejail in, but that starts to degrade performance in noticeable ways (though I've found it's nice to strive for this in your CI).

[hendry]

Agreed! systemd nspawn is actually pretty awesome, though not many people use it.