Using bubblewrap to add sandboxing to NetBSD
blog.netbsd.org
blog.netbsd.org
https://github.com/containers/bubblewrap
It's the base for Flatpack, the thing that makes Flatpack be sandboxed.
I use it to run Claude Code / Codex / Gemini CLI, to make sure that they have a limited / fake view of my system.
You can bind directories into it, or overlay them into it, restrict other kinds of access.
If Docker is a thing in a scale between a VM and your OS, Bubblewrap is a thing a scale between Docker and your OS. You use your OS, instead of installing and managing an OS like you do with Docker, but you get filesystem and process isolation like with Docker.
Though I had an issue where I cannot use `--new-session`, which is kind of dangerous to not use, but you can get around it if you use seccomp to block ioctl calls, and ptrace.
How do you know what permissions are required by an application, to write a bubblewrap script?
In AppArmor, you exercise the application and aa-logprof suggests permissions requested by application. If you know AppArmor, usually you can refine those suggestions and write a profile. It may not be ideal, as aa-logprof’s permissions are multiple choice suggestions, require user knowledge and may be too broad or specific, but it could work. You will see that there are many and all kinds of permissions, and there is no way that you will be able to guess them without aa-logprof.
What is the equivalent of aa-logprof in bubblewrap and how do you find the required permissions?
https://hanako.codeberg.page/ (Flatpak is not a sandbox)
https://github.com/strongdm/leash
It even has a --darwin macOS-native mode which goes beyond the capabilities and guarantees of sandbox-exec and bubblewrap.
Full-disclosure: I am one of the authors.
Moreover it vendores patched gcc compiler, so the entire toolchain is reproducible too as well.
How cool is that?! For the record golang brings it further - its entire package registry containing +40mln packages is bit by bit reproducible.
Freebsd seems like an amazing project too.
I am always confused tho by what is the actual difference b/w freebsd,netbsd,openbsd as I feel like freebsd is taking a lot of positive ideas from both netbsd and openbsd or independently building them.
I might want to play with freebsd one day but I feel like it might have limited software or I might need to compile a lot of things as compared to archlinux or even debian etc.
What they all have in common is that they have great documentation, and they're all very unix-y and all have some virtualization support for linux.
Some things FreeBSD offer are good performance, IME the largest package repository, zfs integration, capsicum and jails. The experience IMO is a bit like Arch, except you'll rely less on a wiki and more on their official documentation.
OpenBSD and NetBSD offer a more "complete" experience like you'd expect from a desktop OS, while at the same time being quite minimal and simple.
OpenBSD focuses a lot on security, and is probably more likely to work with your hardware with fast wifi. It doesn't offer the same virtualization nor security the same type of security as Linux, but instead encourages you to pledge and unveil your applications, which means you lock down each application by saying what it can and can't do. It notoriously removes features from the kernel that are unmaintained and also doesn't include things it considers insecure like bluetooth. It's probably the OS that gives you the most "works out-of-the-box" experience.
NetBSD gives you a full desktop experience as well, but also has some unique security features like kauth, veriexec, extra-hardened chroot and security.curtain. It also offers some cool features like rumpkernels, smolbsd, and is probably the easiest to hack and compile yourself (even cross-compiling is very simple). It has a package manager, pkgsrc, that runs on many other OSes and it's also quite easy to port to new platforms. It's a fun OS to tinker with.
I actually didn't know that openbsd and netbsd offer a more complete experience than as compared to freebsd
I had heard about openbsd a lot as well but freebsd I think is a lot more known in the nas community partially/wholely because of the zfs integration
Capsicum is definitely really interesting as well, I had heard of pledge partially because of justine tunney's cosmopolitan-esque port of pledge to linux and I was always fascinated by it
I wonder what is the state of software of openbsd /bsd's in general. I think another interesting thing that I found was that SSPL license could probably be bypassed if one can run freebsd etc., I am pretty sure that I had read one such comment regarding something similar on HN
Also, if I may ask, what is the difference with the linux kernel itself, I feel like bsd's have some security advantages which might make it a little bit more suitable for multi-tenancy. But the same things can be done in linux as well with things like podman / docker etc. or with firejail/bubblewrap/flatpak but with a higher cost like ram etc. or they can be considered bloated solutions as compared to bsd's but still.
What are some operating openbsd or some other servers which are used and where are they used, I used to see some apache servers in openbsd in some websites but what are your thoughts on the whole situation, I would love to know more about and thanks once again for your insightful comment!
Locking down an Openbsd system is quite easy for example as it tries to have sane defaults. I find myself more in the dark with Linux.
Installing zfs on Linux is possible, but again can be a lot of work and it doesn't cleanly integrate with containers the same way zfs integrates with jails on Freebsd.
This allows independent people to check that provided binaries don't contain malicious stuff for instance. Ultimately, it lets you download binaries instead of rebuilding everything yourself locally if the binaries have been independently reproduced.
You might be interested in checking:
is it a common practice?
The biggest issue is with Linux Kernel itself. Once kernel reproducibility will be handled, we can practically claim Guix, NixOS, Debian or any other Linux distro is reproducible as well, since with little effort we can avoid installing packages which will colour our reproducibility.
For desktop environments it’s a bit worse, but there are huge efforts to make this happen for all packages in package registries of aforementioned distros.
bwrap --dev-bind /dev /dev --tmpfs /tmp -- labwc
bwrap --dev-bind /dev /dev --tmpfs /tmp -- kwin_wayland konsole
bwrap --dev-bind /dev /dev --tmpfs /tmp -- startplasma-wayland
That's obviously super permissive, but from there can take things away to expose as much or little of the host system as needed.
For my system I'm working on making a few bwrapped "zones". E.g. start a terminal that can see a certain subset of files, and can configure whether it should use gpu or not, have internet or not, have access to local network or not, etc. A bit more project/environment focused than bwrapping programs one by one.
But firejail needs root privilege, so there are arguments that it may actually reduce the security, because even though it sandboxes some applications, non-privilege processes may gain privilege if there is a flaw in the fire jail itself.
Firejail is also criticized for complexity.
Complexity? It just supports a lot of stuff. See the manual page. It seems simple enough to me.
Complexity referred to large code base and attack surface.
I haven’t tried it myself. I would be interested knowing, whether it might lower the security in some cases. Maybe it’s useful to sandbox apps that don’t have flatpaks.
My gut sense is that flatpak gets much more scrutiny since it ships, and firejail is typically not shipped, but another package as far as I can tell (maybe in some specialized distros?).
Still, it can happen of course, particularly with memory-unsafe languages. Conversely without root privileges you have to sacrifice strength of your sandbox, widening the vulnerability window in the app you were trying to constrain to begin with.
Meanwhile bubblewrap relies on user namespaces, which come with their own set of security problems. They are disabled by default in many distributions for that reason.
A lot of focus in flatpak sadly gets focused on guis and not clis
Like how much efforts would it take to convert a golang static binary/project cli to flatpak?