secureblue

This repo uses BlueBuild to generate hardened operating system images, using uBlue's Fedora Atomic-based 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 uBlue and BlueBuild, check out the uBlue homepage and 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, and Sericea (Sway Atomic) for Sericea and all the Wayblue images.

To rebase a Fedora Atomic installation, choose an $IMAGE_NAME from the list below, then follow these steps:

(Important note: 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
```

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 ^userns?

Desktop

Recommended ^why?

silverblue-main-hardened
silverblue-nvidia-hardened
silverblue-main-userns-hardened
silverblue-nvidia-userns-hardened

Stable

kinoite-main-hardened
kinoite-nvidia-hardened
kinoite-main-userns-hardened
kinoite-nvidia-userns-hardened
sericea-main-hardened
sericea-nvidia-hardened
sericea-main-userns-hardened
sericea-nvidia-userns-hardened

Beta ^wayblue?

wayblue-wayfire-main-hardened
wayblue-wayfire-nvidia-hardened
wayblue-wayfire-main-userns-hardened
wayblue-wayfire-nvidia-userns-hardened
wayblue-hyprland-main-hardened
wayblue-hyprland-nvidia-hardened
wayblue-hyprland-main-userns-hardened
wayblue-hyprland-nvidia-userns-hardened
wayblue-river-main-hardened
wayblue-river-nvidia-hardened
wayblue-river-main-userns-hardened
wayblue-river-nvidia-userns-hardened
wayblue-sway-main-hardened
wayblue-sway-nvidia-hardened
wayblue-sway-main-userns-hardened
wayblue-sway-nvidia-userns-hardened

Experimental

cinnamon-main-hardened
cinnamon-nvidia-hardened
cinnamon-main-userns-hardened
cinnamon-nvidia-userns-hardened
cosmic-main-hardened
cosmic-nvidia-hardened
cosmic-main-userns-hardened
cosmic-nvidia-userns-hardened

Server

securecore-main-hardened
securecore-nvidia-hardened
securecore-main-userns-hardened
securecore-nvidia-userns-hardened
securecore-zfs-main-hardened
securecore-zfs-nvidia-hardened
securecore-zfs-main-userns-hardened
securecore-zfs-nvidia-userns-hardened

Asus ^source

silverblue-asus-hardened
silverblue-asus-nvidia-hardened
silverblue-asus-userns-hardened
silverblue-asus-nvidia-userns-hardened
kinoite-asus-hardened
kinoite-asus-nvidia-hardened
kinoite-asus-userns-hardened
kinoite-asus-nvidia-userns-hardened

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.

KernelFreeze/secureblue