Linux-hardened and Flatpak, Distrobox, Podman, Docker

Pantherina@feddit.de to Linux@lemmy.ml – 44 points –

Hi guys!

I am currently trying Arch in a VM and I like it a lot. Wanted to try the hardened kernel all the time, but it has the problem of forbidding custom namespaces.

Tbh I dont even know what that is, but on arch, installing bubblewrap-suid fixes the flatpak problem.

I could not find such a package for Podman, which is used as backend (?) in Distrobox.

Is there a way to make Podman, Docker, Distrobox, Toolbox work on linux-hardened?

This is a big requirement for making a Fedora Atomic version using the hardened kernel, which sounds great, as they completely rely on these containers.

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Tools like Podman, Docker, Distrobox and Toolbox use custom uid namespaces. I don’t see how they could work with them disabled.

With a specific exception only for one software. I would be happy with Flatpak and Podman. Maybe Waydroid and wine too though?

Wine should just work.
Waydroid needs extra support from the kernel that linux-hardend has disabled at compile time. There's a DKMS solution however.

This one? it doesnt mention the hardened kernel at all, is this some obsolete modification not needed in modern Kernels?

Basically, you want to not disable kernel.unprivileged_userns_clone.

For a temporary solution that has to be redone after reboot, there is sysctl kernel.unprivileged_userns_clone=1.

For a lasting solution, consider echo kernel.unprivileged_userns_clone=1 | sudo tee /etc/sysctl.d/99-enable-unpriv-userns.conf.

In either case you're foregoing security for the sake of convenience/functionality, so I understand why you would rather not act upon either of them.

I don't know what the solution is that would be analogous to installing bubblewrap-suid. Perhaps, it's worth exploring the projects found within the github page of Awesome Fedora Security for some pointers.

If you are running things inside of containers you aren’t helping yourself by disabling unprivileged namespaces, you are actually just running more things as root. Inside the containers they generally block namespaces anyway.

TBH I’ve never heard anything positive about most of what hardened does.

I guess I would just disable this one hardening setting like another person recommended.