secureblue / secureblue

Hardened Fedora Atomic and Fedora CoreOS images

secureblue

This repo uses BlueBuild to generate hardened operating system images, using Fedora Atomic Desktop's base images as a starting point.

Scope

secureblue applies hardening with the following goals in mind:

• Increase defenses against the exploitation of both known and unknown vulnerabilities.
• Avoid sacrificing usability for most use cases where possible.

The following are not in scope:

• Anything that sacrifices security for "privacy". Fedora is already sufficiently private and "privacy" often serves as a euphemism for security theater. This is especially true when at odds with improving security.
• Anything related to "degoogling" chromium. For example, we will not be replacing hardened-chromium with Brave or ungoogled-chromium. Both of them make changes that sacrifice security for "privacy", such as enabling MV2. ^why?

Hardening

• Installing and enabling hardened_malloc globally, including for flatpaks. ^{Thanks to rusty-snake's spec}
• Installing hardened-chromium, which is inspired by Vanadium. ^{Why chromium? Why not flatpak chromium?}
• Setting numerous hardened sysctl values ^details
• Remove SUID-root from numerous binaries and replace functionality using capabilities
• Disable Xwayland by default (for GNOME, Plasma, and Sway images)
• Mitigation of LD_PRELOAD attacks via ujust toggle-bash-environment-lockdown
• Disabling coredumps
• Disabling all ports and services for firewalld
• Adds per-network MAC randomization
• Blacklisting numerous unused kernel modules to reduce attack surface ^details
• Enabling only the flathub-verified remote by default
• Sets numerous hardening kernel arguments (Inspired by Madaidan's Hardening Guide) ^details
• Reduce the sudo timeout to 1 minute
• Require wheel user authentication via polkit for rpm-ostree install ^why?
• Brute force protection by locking user accounts for 24 hours after 50 failed login attempts, hardened password encryption and password quality suggestions
• Installing usbguard and providing ujust commands to automatically configure it
• Installing bubblejail for additional sandboxing tooling
• Set opportunistic DNSSEC and DNSOverTLS for systemd-resolved
• Configure chronyd to use Network Time Security (NTS) ^{using chrony config from GrapheneOS}
• Disable KDE GHNS by default ^why?
• Disable install & usage of GNOME user extensions by default
• Use HTTPS for all rpm mirrors
• Set all default container policies to reject, signedBy, or sigstoreSigned
• Disable a variety of services by default (including cups, geoclue, passim, and others)
• Removal of the unmaintained and suid-root fuse2 by default
• (Non-userns variants) Disabling unprivileged user namespaces
• (Non-userns variants) Replacing bubblewrap with suid-root bubblewrap so flatpak can be used without unprivileged user namespaces

Rationale

Fedora is one of the few distributions that ships with selinux and associated tooling built-in and enabled by default. This makes it advantageous as a starting point for building a hardened system. However, out of the box it's lacking hardening in numerous other areas. This project's goal is to improve on that significantly.

For more info on BlueBuild, check out the BlueBuild homepage.

Customization

If you want to add your own customizations on top of secureblue, you are advised strongly against forking. Instead, create a repo for your own image by using the BlueBuild template, then change your base-image to a secureblue image. This will allow you to apply your customizations to secureblue in a concise and maintainable way, without the need to constantly sync with upstream.

FAQ

If you're encountering a problem or have a question, please consult the FAQ. If you can't find your answer there, please ask in the support channel on Discord.

Sponsor

Sponsorship options are on the Donate page. All donations are appreciated. Sponsors get a role on the Discord if desired. If you've donated but haven't yet been tagged with the role, please reach out to me.

Installation

Have a look at PREINSTALL-README before proceeding.

Rebasing (Recommended)

Note

If you don't already have a Fedora Atomic installation, use a Fedora Atomic ISO that matches your secureblue target image to install one. If you want to use a secureblue Silverblue image, start with the Fedora Silverblue ISO, Kinoite for Kinoite, Sericea (Sway Atomic) for Sericea and all the Wayblue images, and CoreOS for all the securecore images.

To rebase a Fedora Atomic or Fedora CoreOS installation, follow these steps^‡:

Important

The only supported tag is latest.

• First rebase to the unsigned image, to get the proper signing keys and policies installed:

  rpm-ostree rebase ostree-unverified-registry:ghcr.io/secureblue/IMAGE_NAME:latest
  

• Reboot to complete the rebase:

  systemctl reboot
  

• Then rebase to the signed image, like so:

  rpm-ostree rebase ostree-image-signed:docker://ghcr.io/secureblue/IMAGE_NAME:latest
  

• Reboot again to complete the installation:

  systemctl reboot
  

^‡ Replace IMAGE_NAME with the full name of your preferred image from the list below.

ISO

While it's recommended to use a Fedora Atomic ISO to install and then rebase that installation to secureblue, you can also generate an ISO and install that directly using this script. Please note you should still follow the post-install steps when installing from a generated ISO:

./generate_secureblue_iso.sh

Images

Note

Learn about unprivileged user namespaces here.

Desktop

nvidia-open images are recommended for systems with Nvidia GPUs Turing or newer. These include the new open kernel modules from Nvidia, not Nouveau.

nvidia images are recommended for systems with Nvidia GPUs Pascal or older. These include the closed kernel modules from Nvidia.

Recommended ^why?

Silverblue

Name	Base	Nvidia Support	Unpriv. Userns
silverblue-main-hardened	Silverblue	No	No
silverblue-nvidia-hardened	Silverblue	Yes, closed drivers	No
silverblue-nvidia-open-hardened	Silverblue	Yes, open drivers	No
silverblue-main-userns-hardened	Silverblue	No	Yes
silverblue-nvidia-userns-hardened	Silverblue	Yes, closed drivers	Yes
silverblue-nvidia-open-userns-hardened	Silverblue	Yes, open drivers	Yes

Stable

Kinoite

Name	Base	Nvidia Support	Unpriv. Userns
kinoite-main-hardened	Kinoite	No	No
kinoite-nvidia-hardened	Kinoite	Yes, closed drivers	No
kinoite-nvidia-open-hardened	Kinoite	Yes, open drivers	No
kinoite-main-userns-hardened	Kinoite	No	Yes
kinoite-nvidia-userns-hardened	Kinoite	Yes, closed drivers	Yes
kinoite-nvidia-open-userns-hardened	Kinoite	Yes, open drivers	Yes

Sericea

Name	Base	Nvidia Support	Unpriv. Userns
sericea-main-hardened	Sericea	No	No
sericea-nvidia-hardened	Sericea	Yes, closed drivers	No
sericea-nvidia-open-hardened	Sericea	Yes, open drivers	No
sericea-main-userns-hardened	Sericea	No	Yes
sericea-nvidia-userns-hardened	Sericea	Yes, closed drivers	Yes
sericea-nvidia-open-userns-hardened	Sericea	Yes, open drivers	Yes

Beta

Note

Learn about wayblue here.

Wayfire

Name	Base	Nvidia Support	Unpriv. Userns
wayblue-wayfire-main-hardened	Wayblue-Wayfire	No	No
wayblue-wayfire-nvidia-hardened	Wayblue-Wayfire	Yes, closed drivers	No
wayblue-wayfire-nvidia-open-hardened	Wayblue-Wayfire	Yes, open drivers	No
wayblue-wayfire-main-userns-hardened	Wayblue-Wayfire	No	Yes
wayblue-wayfire-nvidia-userns-hardened	Wayblue-Wayfire	Yes, closed drivers	Yes
wayblue-wayfire-nvidia-open-userns-hardened	Wayblue-Wayfire	Yes, open drivers	Yes

Hyprland

Name	Base	Nvidia Support	Unpriv. Userns
wayblue-hyprland-main-hardened	Wayblue-Hyprland	No	No
wayblue-hyprland-nvidia-hardened	Wayblue-Hyprland	Yes, closed drivers	No
wayblue-hyprland-nvidia-open-hardened	Wayblue-Hyprland	Yes, open drivers	No
wayblue-hyprland-main-userns-hardened	Wayblue-Hyprland	No	Yes
wayblue-hyprland-nvidia-userns-hardened	Wayblue-Hyprland	Yes, closed drivers	Yes
wayblue-hyprland-nvidia-open-userns-hardened	Wayblue-Hyprland	Yes, open drivers	Yes

River

Name	Base	Nvidia Support	Unpriv. Userns
wayblue-river-main-hardened	Wayblue-River	No	No
wayblue-river-nvidia-hardened	Wayblue-River	Yes, closed drivers	No
wayblue-river-nvidia-open-hardened	Wayblue-River	Yes, open drivers	No
wayblue-river-main-userns-hardened	Wayblue-River	No	Yes
wayblue-river-nvidia-userns-hardened	Wayblue-River	Yes, closed drivers	Yes
wayblue-river-nvidia-open-userns-hardened	Wayblue-River	Yes, open drivers	Yes

Sway

Name	Base	Nvidia Support	Unpriv. Userns
wayblue-sway-main-hardened	Wayblue-Sway	No	No
wayblue-sway-nvidia-hardened	Wayblue-Sway	Yes, closed drivers	No
wayblue-sway-nvidia-open-hardened	Wayblue-Sway	Yes, open drivers	No
wayblue-sway-main-userns-hardened	Wayblue-Sway	No	Yes
wayblue-sway-nvidia-userns-hardened	Wayblue-Sway	Yes, closed drivers	Yes
wayblue-sway-nvidia-open-userns-hardened	Wayblue-Sway	Yes, open drivers	Yes

Server

Note

After you finish setting up your Fedora CoreOS installation, you will need to disable zincati.service before rebasing to securecore.

Name	Base	Nvidia Support	ZFS Support	Unpriv. Userns
securecore-main-hardened	CoreOS	No	No	No
securecore-nvidia-hardened	CoreOS	Yes, closed drivers	No	No
securecore-nvidia-open-hardened	CoreOS	Yes, open drivers	No	No
securecore-main-userns-hardened	CoreOS	No	No	Yes
securecore-nvidia-userns-hardened	CoreOS	Yes, closed drivers	No	Yes
securecore-nvidia-open-userns-hardened	CoreOS	Yes, open drivers	No	Yes
securecore-zfs-main-hardened	CoreOS	No	Yes	No
securecore-zfs-nvidia-hardened	CoreOS	Yes, closed drivers	Yes	No
securecore-zfs-nvidia-open-hardened	CoreOS	Yes, open drivers	Yes	No
securecore-zfs-main-userns-hardened	CoreOS	No	Yes	Yes
securecore-zfs-nvidia-userns-hardened	CoreOS	Yes, closed drivers	Yes	Yes
securecore-zfs-nvidia-open-userns-hardened	CoreOS	Yes, open drivers	Yes	Yes

Experimental

Cosmic

Name	Base	Nvidia Support	Unpriv. Userns
cosmic-main-hardened	Cosmic	No	No
cosmic-nvidia-hardened	Cosmic	Yes, closed drivers	No
cosmic-nvidia-open-hardened	Cosmic	Yes, open drivers	No
cosmic-main-userns-hardened	Cosmic	No	Yes
cosmic-nvidia-userns-hardened	Cosmic	Yes, closed drivers	Yes
cosmic-nvidia-open-userns-hardened	Cosmic	Yes, open drivers	Yes

Post-install

After installation, yafti will open. Make sure to follow the steps listed carefully and read the directions closely.

Then follow the POSTINSTALL-README.

Contributing

Follow the contributing documentation, and make sure to respect the CoC.

Development

For local Development building locally is the recommended approach.

Community

Opening issues is preferred, but Discord is available as well.