Installing Debian or Devuan GNU+Linux with full disk encryption (including /boot)

This guide is written for the Debian distribution, but it should also work for Devuan with the net installer.

To boot the Trisquel net installer, make sure to specify fb=false on the linux kernel parameters in GRUB. This will boot the installer in text mode instead of using a framebuffer.

Libreboot on x86 uses the GRUB payload by default, which means that the GRUB configuration file (where your GRUB menu comes from) is stored directly alongside libreboot and its GRUB payload executable, inside the flash chip. In context, this means that installing distributions and managing them is handled slightly differently compared to traditional BIOS systems.

On most systems, the /boot partition has to be left unencrypted while the others are encrypted. This is so that GRUB, and therefore the kernel, can be loaded and executed since the firmware can’t open a LUKS volume. Not so with libreboot! Since GRUB is already included directly as a payload, even /boot can be encrypted. This protects /boot from tampering by someone with physical access to the system.

This guide is written for Debian net installer. You can download the ISO from the homepage on debian.org. Use this on the GRUB terminal to boot it from USB (for 64-bit Intel or AMD):

set root='usb0' linux /install.amd/vmlinuz initrd /install.amd/initrd.gz boot

If you are on a 32-bit system (e.g. X60):

set root='usb0' linux /install.386/vmlinuz initrd /install.386/initrd.gz boot

This guide shows how to create a boot USB drive with the Debian ISO image.

This guide is only for the GRUB payload. If you use the depthcharge payload, ignore this section entirely.

Note: on some thinkpads, a faulty DVD drive can cause the cryptomount -a step during boot to fail. If this happens to you, try removing the drive.

Set a strong user password (lots of lowercase/uppercase, numbers and symbols).

Use of the diceware method is recommended, for generating secure passphrases (instead of passwords).

When the installer asks you to set up encryption (ecryptfs) for your home directory, select ‘Yes’ if you want to: LUKS is already secure and performs well. Having ecryptfs on top of it will add noticeable performance penalty, for little security gain in most use cases. This is therefore optional, and not recommended. Choose ‘no’.

Your user password should be different from the LUKS password which you will set later on. Your LUKS password should, like the user password, be secure.

Choose ‘Manual’ partitioning:

Select drive and create new partition table

Single large partition. The following are mostly defaults: Use as: physical volume for encryption Encryption: aes key size: whatever default is given to you IV algorithm: whatever default is given to you Encryption key: passphrase erase data: Yes (only choose ‘No’ if it’s a new drive that doesn’t contain your private data)

Select ‘configure encrypted volumes’ Create encrypted volumes Select your partition Finish Really erase: Yes (erase will take a long time. be patient) (if your old system was encrypted, just let this run for about a minute to make sure that the LUKS header is wiped out)

Select encrypted space: use as: physical volume for LVM Choose ‘done setting up the partition’

Configure the logical volume manager: Keep settings: Yes

Create volume group: Name: matrix (use this exact name) Select crypto partition

Create logical volume select matrix (use this exact name) name: rootvol (use this exact name) size: default, minus 2048 MB

Create logical volume select matrix (use this exact name) name: swap (user this exact name) size: press enter



Further partitioning [link]

Now you are back at the main partitioning screen. You will simply set mountpoints and filesystems to use.

LVM LV rootvol use as: btrfs mount point: / done setting up partition

LVM LV swap use as: swap area done setting up partition

Now you select ‘Finished partitioning and write changes to disk’.

Installation will ask what kernel you want to use. linux-generic is fine.

For Debian, use the MATE option, or one of the others if you want. The libreboot project recommends MATE, unless you’re saavy enough to choose something else.

If you want debian-testing, then you should only select barebones options here and change the entries in /etc/apt/sources.list after install to point to the new distro, and then run apt-get update and apt-get dist-upgrade as root, then reboot and run tasksel as root. This is to avoid downloading large packages twice.

NOTE: If you want the latest up to date version of the Linux kernel, Debian’s kernel is sometimes outdated, even in the testing distro. You might consider using this repository instead, which contains the most up to date versions of the Linux kernel. These kernels are also deblobbed, like Debian’s kernels, so you can be sure that no binary blobs are present.

Postfix configuration [link]

If asked, choose “No Configuration” here (or maybe you want to select something else. It’s up to you.)

Install the GRUB boot loader to the master boot record [link]

Choose ‘Yes’. It will fail, but don’t worry. Then at the main menu, choose ‘Continue without a bootloader’. You could also choose ‘No’. Choice is irrelevant here.

Don’t forget to have grub-coreboot package installed, even though installing grub to MBR is irrelevant on libreboot system, grub tools are still needed to eg. generate config ( grub-mkconfig )

Clock UTC [link]

Just say ‘Yes’.

Booting your system [link]

At this point, you will have finished the installation. At your GRUB payload, press C to get to the command line, and enter:

grub> cryptomount -a grub> set root='lvm/matrix-rootvol' grub> linux /vmlinuz root=/dev/mapper/matrix-rootvol cryptdevice=/dev/mapper/matrix-rootvol:root grub> initrd /initrd.img grub> boot

If you didn’t encrypt your home directory, then you can safely ignore this section.

Immediately after logging in, do that:

$ sudo ecryptfs-unwrap-passphrase

This will be needed in the future if you ever need to recover your home directory from another system, so write it down and keep the note somewhere secret. Ideally, you should memorize it and then burn the note (or not even write it down, and memorize it still)>

Now you need to set it up so that the system will automatically boot, without having to type a bunch of commands.

Install grub-coreboot if not already installed:

# apt-get install grub-coreboot

Modify or add following lines to /etc/default/grub

GRUB_CMDLINE_LINUX="cryptdevice=/dev/mapper/matrix-rootvol:root" GRUB_ENABLE_CRYPTODISK=y

Copy fonts/backgrounds to /boot/grub and generate grub.cfg using following command:

# grub-install --target=i386-coreboot

Refer to this guide for further guidance on hardening your GRUB configuration, for security purposes.

LUKSv2 incompatibility [link]

When using libreboot version 20160907 and older it may be necessary to downgrade LUKSv2 to LUKSv1. See debian’s cryptsetup-team page to learn how to downgrade.

A user reported issues when booting with a docking station attached on an X200, when decrypting the disk in GRUB. The error AHCI transfer timed out was observed. The workaround was to remove the docking station.

Further investigation revealed that it was the DVD drive causing problems. Removing that worked around the issue.

"sudo wodim -prcap" shows information about the drive: Device was not specified. Trying to find an appropriate drive... Detected CD-R drive: /dev/sr0 Using /dev/cdrom of unknown capabilities Device type : Removable CD-ROM Version : 5 Response Format: 2 Capabilities : Vendor_info : 'HL-DT-ST' Identification : 'DVDRAM GU10N ' Revision : 'MX05' Device seems to be: Generic mmc2 DVD-R/DVD-RW. Drive capabilities, per MMC-3 page 2A: Does read CD-R media Does write CD-R media Does read CD-RW media Does write CD-RW media Does read DVD-ROM media Does read DVD-R media Does write DVD-R media Does read DVD-RAM media Does write DVD-RAM media Does support test writing Does read Mode 2 Form 1 blocks Does read Mode 2 Form 2 blocks Does read digital audio blocks Does restart non-streamed digital audio reads accurately Does support Buffer-Underrun-Free recording Does read multi-session CDs Does read fixed-packet CD media using Method 2 Does not read CD bar code Does not read R-W subcode information Does read raw P-W subcode data from lead in Does return CD media catalog number Does return CD ISRC information Does support C2 error pointers Does not deliver composite A/V data Does play audio CDs Number of volume control levels: 256 Does support individual volume control setting for each channel Does support independent mute setting for each channel Does not support digital output on port 1 Does not support digital output on port 2 Loading mechanism type: tray Does support ejection of CD via START/STOP command Does not lock media on power up via prevent jumper Does allow media to be locked in the drive via PREVENT/ALLOW command Is not currently in a media-locked state Does not support changing side of disk Does not have load-empty-slot-in-changer feature Does not support Individual Disk Present feature Maximum read speed: 4234 kB/s (CD 24x, DVD 3x) Current read speed: 4234 kB/s (CD 24x, DVD 3x) Maximum write speed: 4234 kB/s (CD 24x, DVD 3x) Current write speed: 4234 kB/s (CD 24x, DVD 3x) Rotational control selected: CLV/PCAV Buffer size in KB: 1024 Copy management revision supported: 1 Number of supported write speeds: 4 Write speed # 0: 4234 kB/s CLV/PCAV (CD 24x, DVD 3x) Write speed # 1: 2822 kB/s CLV/PCAV (CD 16x, DVD 2x) Write speed # 2: 1764 kB/s CLV/PCAV (CD 10x, DVD 1x) Write speed # 3: 706 kB/s CLV/PCAV (CD 4x, DVD 0x) Supported CD-RW media types according to MMC-4 feature 0x37: Does write multi speed CD-RW media Does write high speed CD-RW media Does write ultra high speed CD-RW media Does not write ultra high speed+ CD-RW media

Copyright © 2014, 2015, 2016 Leah Rowe info@minifree.org

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