bubblewrap VS runc

Nothing nix specific but you may be interested in https://github.com/containers/bubblewrap

Recently, I came across Chainguard and wrote the article How to build Docker Images with Melange and Apko. As a fervent supporter of Kubernetes and GitLab CI, I was eager to experiment with building images using Melange in this particular setup. GitLab's shared Runners work seamlessly with Bubblewrap, eliminating the need for additional configurations. This post is intended for enthusiasts like myself, interested in hosting their own Kubernetes Runners and leveraging the Kubernetes Runner Type of Melange.

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This is basically manually invoking what Flatpak does:

https://github.com/containers/bubblewrap

This is also useful for more than just security. E.G., you can test how your app would behave on a fresh install by masking your user configuration files. I personally also have a tool that uses it to basically bundle all dependencies from an entire Linux distribution in order to make highly portable AppImages— Been meaning to post that, will get around to it eventually maybe.

The flags above should hide your user data (`--tmpfs`), disable network access (`--unshare-all`), hide/virtualize devices and OS state (`--dev` and `--proc`), and make the rest of the root filesystem read-only (`--ro-bind`­— Including the insecure X11 socket in `/tmp`, which you might want to expose for GUI apps).

Check them against `bwrap --help`; I might have omitted one or two more things you'd need.

While trying to find out more comparison information, found this light on details issue:

https://github.com/containers/bubblewrap/issues/81

It mentions nsjail and minijail.

I can speak to this. Containers, and by extension k8s, break a well known security boundary that has existed for a very long time - whether you are using a real (hardware) server or a virtual machine on the cloud if you pop that instance/server generally speaking you only have access to that server. Yeh, you might find a db config with connection details if you landed on say a web app host but in general you still have to work to start popping the next N servers.

That's not the case when you are running in k8s and the last container breakout was just announced ~1 month ago: https://github.com/opencontainers/runc/security/advisories/G... .

At the end of the day it is simply not a security boundary. It can solve other problems but not security ones.

It's interesting that, in light of things like this, you still see large software companies adding support for new components written in non-memory safe languages (e.g. C)

As an example Red Hat OpenShift added support for crun(https://github.com/containers/crun) this year(https://cloud.redhat.com/blog/whats-new-in-red-hat-openshift...), which is written in C as an alternative to runc, which is written in Go(https://github.com/opencontainers/runc)...

Rabbit hole indeed. That wasn't related to my job at the time, lol. The job change came with a company-provided computer and that put an end to the tinkering.

BTW, I found my hacks to make runc run on Chromebook: https://github.com/opencontainers/runc/compare/main...gabrys...

being the main author of crun, I can clarify that statement: I am not a fan of Go _for this particular use case_.

Using C instead of Go avoided a bunch of the workarounds that exists in runc to workaround the Go runtime, e.g. https://github.com/opencontainers/runc/blob/main/libcontaine...

runc

Not OP, but if I had to guess, a lot of this can be picked up by just observing common security issues in the Linux space, since similar mistakes and oversights have caused quite a few real-world CVEs in the past, e.g. this random example of a TOCTTOU vulnerability in runc.