sig-security VS ostree

Cloud Native Security Whitepaper

As Daniel Walsh himself wrote in a blog post, CRI-O integrates very well with SELinux and prevents dangerous actions like a container loading an old, unmaintained and therefore potentially vulnerable kernel module and breaking out of the isolation. Additionally, the Kubernetes API itself contains resources to specifically configure SELinux labels for containers. Doesn't sound like something they would do for a tool that "doesn't work with Kubernetes", according to some. Also, the CNCF security whitepaper mentions SELinux as a tool that can be used to provide isolation and limit privileges, which is as much as we could expect from an high-level, architecturally-minded document.

Fortunately, not every attack has a big enough impact to appear in the newspaper, but let’s analyze some of the most relevant and recent ones. Many other examples of different types of supply chain attacks are also collected by the CNCF in their Catalog of Supply Chain Compromises.

Ansible makes mutable changes to the OS, task by task.

Nix is immutable. A new change is made entirely new, and only after the build is successful, all packages are "symlinked" to the current system.

Fedora Silverblue is based on ostree [1]. It works similarly like git, but on your root tree. But it requires you to reboot the whole system for the changes to take effect. Since Nix is just symlinked packages, you don't need to reboot the system.

More detailed explanation here [2].

[1]: https://github.com/ostreedev/ostree

[2]: https://dataswamp.org/~solene/2023-07-12-intro-to-immutable-...

This one is for the ostree bug currently ongoing: https://github.com/ostreedev/ostree/issues/2900

This sounds related to the ostree bug.

I definitely agree that immutability offers considerable value in regards to improving security. But arguably it's insufficient to pull the win over mutable Fedora due to the losses caused by the inability to install the kernel-hardened package and the lack of UKI (Unified Kernel Image) support.

Other hardening guides mention a Unified Kernel Image as another measure to further improve security. Unfortunately, once more, this is (currently) not supported on Fedora Silverblue. I haven't seen it being done on openSUSE Aeon either. Though, once again, I'd love to be corrected!

The fedora crew is working on it through ostree though, so both fedora Silverblue and flatpak will be getting it (as well as true immutability) in the future: https://github.com/ostreedev/ostree/issues/2867

Aside from what has already been mentioned, Unified Kernel Image isn't supported (yet).