Introduction

This is my fork of easy-arch, a script made in order to boostrap a basic Arch Linux environment with snapshots and encryption by using a fully automated process (UEFI only).

This fork comes with various security improvements and fully working rollbacks with snapper. I do submit some of the changes here back to upstream as well.

Visit my Matrix group: https://matrix.to/#/#tommytran732:matrix.org

How does it work?

1. Download an Arch Linux ISO from here
2. Flash the ISO onto an USB Flash Drive.
3. Boot the live environment.
4. Connect to the internet.
5. git clone https://github.com/tommytran732/Arch-Setup-Script/
6. cd Arch-Setup-Script
7. ./install.sh

Secure Boot

The Secure Boot script can be run after you have rebooted into the system to automate the process of generating your own keys and setting up Secure Boot described at https://wiki.archlinux.org/title/Unified_Extensible_Firmware_Interface/Secure_Boot. Please make sure that your firmware is in Setup mode and the TPM is disabled.

Currently, there is an problem where GRUB requires tpm.mod to be included for signature verification, but if tpm.mod is included and the TPM is enabled it will also attempt to do Measured Boot, breaking the Arch Linux snapshots menu created by grub-btrfs. I have yet to find a solution for this issue.

Changes to the original project

1. Encrypted /boot with LUKS1
2. SUSE - like partition layout and fully working snapper snapshots & rollback
3. Minimally setup GNOME with pipewire
4. AppArmor and Firewalld enabled by default
5. Defaulting umask to 077
6. Randomize Mac Address and disable Connectivity Check for privacy
7. Added some kernel/grub settings from https://github.com/Whonix/security-misc/tree/master/etc/default
8. Added Secure Boot script

Snapper behavior

The partition layout I use rallows us to replicate the behavior found in openSUSE 🦎

1. Snapper rollback works! You will no longer need to manually rollback from a live USB like you would with the @ and @home layout suggested in the Arch Wiki.
2. You can boot into a readonly snapshot! GDM and other services will start normally so you can get in and verify that everything works before rolling back.
3. Automatic snapshots on pacman install/update/remove operations
4. Directories such as /boot, /boot/efi, /var/log, /var/crash, /var/tmp, /var/spool, /var/lib/libvirt/images are excluded from the snapshots as they either should be persistent or are just temporary files. /cryptkey is excluded as we do not want the encryption key to be included in the snapshots, which could be sent to another device as a backup.
5. GRUB will boot into the default BTRFS snapshot set by snapper. Like on SUSE, your running system will always be a read-write snapshot in @/.snapshots/X/snapshot.

Partitions layout

Partition/Subvolume	Label	Mountpoint	Notes
1	ESP	/boot/efi	Unencrypted FAT32
2	@/.snapshots/X/snapshot	/	Encrypted BTRFS
3	@/boot	/boot/	Encrypted BTRFS (nodatacow)
4	@/root	/root	Encrypted BTRFS
5	@/home	/home	Encrypted BTRFS
6	@/.snapshots	/.snapshots	Encrypted BTRFS
7	@/srv	/srv	Encrypted BTRFS (nodatacow)
8	@/var_log	/var/log	Encrypted BTRFS (nodatacow)
9	@/var_log/journal	/var/log/journal	Encrypted BTRFS (nodatacow)
10	@/var_crash	/var/crash	Encrypted BTRFS (nodatacow)
11	@/var_cache	/var/cache	Encrypted BTRFS (nodatacow)
12	@/var_tmp	/var/tmp	Encrypted BTRFS (nodatacow)
13	@/var_spool	/var/spool	Encrypted BTRFS (nodatacow)
14	@/var_lib_libvirt_images	/var/lib/libvirt/images	Encrypted BTRFS (nodatacow)
15	@/var_lib_machines	/var/lib/machines	Encrypted BTRFS (nodatacow)
16	@/var_lib_gdm	/var/lib/gdm	Encrypted BTRFS (nodatacow)
17	@/var_lib_AccountsService	/var/lib/AccountsService	Encrypted BTRFS (nodatacow)
18	@/cryptkey	/cryptkey	Encrypted BTRFS (nodatacow)

LUKS1 and Encrypted /boot (Mumbo Jumbo stuff)

This is the same setup that is used on openSUSE. One problem with the way Secure Boot currently works is that the initramfs and a variety of things in /boot are not validated by GRUB whatsoever, even if Secure Boot is active. Thus, they are vulnerable to tampering. My approach as of now is to encrypt the entire /boot partition and have the only that is unencrypted - the grubx64.efi stub - validated by the firmware.

Ideally, I could use GRUB's GPG verification for the initramfs and its configuration files and what not, but then I need to create hooks to sign them everytime they get updated (when a new initramfs gets generated, when grub-btrfs.path gets triggered, when grub gets updated and its config files change, etc). It is quite a tedious task and I have yet to implement or test this out.

As for why LUKS1 is used, GRUB 2.06 does not work nicely with LUKS2 yet. grub-install will not make GRUB auto detect the LUKS2 partition, and GRUB itself does not support Argon2id (cryptsetup default) as of now anyways. It makes little sense to use GRUB with LUKS2 in its current state, thus I am using LUKS1 to avoid the headache.

You may also see an a keyfile being created by the script and stored at /cryptkey. This is to avoid getting 2 encryption password prompts (one for GRUB to decrypt the disk so that it can get to the kernel, the initramfs and configuration files and one for the kernel itself to start up the rest of the boot process). As the key resides on an encrypted partition (and so does the initramfs that stores a copy of it), security risks should be minimal. The only time an attacker would have access to it is when they have root, at which point you have a much, much more serious problem. The procedure I am using is describe at https://en.opensuse.org/SDB:Encrypted_root_file_system.