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Rootfs over encrypted lvm

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Revision as of 09:36, November 24, 2020 by Pnoecker (talk | contribs) (→‎Grub2 configuration: already done)
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This howto describes how to setup LVM and rootfs with cryptoLUKS-encrypted drive. It is not meant to be a standalone installation guide, rather, it is meant to be read alongside the Funtoo Linux Installation Guide.

Prepare the hard drive and partitions

  • List the device to be partitioned, mine is on /dev/sdc
root # lsblk -o name,size,label,partlabel

Partition

root # cgdisk /dev/sdc

delete everything. 

Command:  new ↵
First sector: ↵
Last sector: +1M ↵
Hex Code: EF02 ↵
Enter name: BIOS Boot ↵

scroll down to large chunk of free space: 

Command: new ↵
First sector: ↵
Last sector: +128M ↵
Hex Code: EF00 ↵
Enter name: BOOT ↵

scroll down to large chunk of free space: 

Command: new ↵
First sector: ↵
Last sector: ↵
Hex Code:  8304 ↵
Enter name: FUNTOO ↵
Disk Drive: /dev/sdc
                            Size: 62333952, 29.7 GiB

Part. #     Size        Partition Type            Partition Name
----------------------------------------------------------------
            1007.0 KiB  free space
   1        1024.0 KiB  BIOS boot partition	  BIOS Boot
   2        256.0 MiB   EFI System                BOOT
   3        29.5 GiB    Linux x86-64 root (/)     FUNTOO
Command: write ↵
Command: quit ↵

Encrypting the drive

Read more about different cipher options here: [1] 

root # cryptsetup luksFormat /dev/sda3

Or use SHA512 for increase security. Do NOT use SHA-1: LUKS disk encryption. As the cryptography expert Bruce Schneier already told in year 2005, do not use SHA-1 because its broken. See his article here: [2] 

root # cryptsetup --cipher twofish-xts-plain64 --hash sha512 --key-size 256 luksFormat /dev/sda3
   Warning

Support for twofish-xts-plain64 is NOT in the default debian-kernel. You will need to configure and compile your own kernel if you choose this.

Initializes the volume

Initializes the volume, and sets an initial key or passphrase: 

root # cryptsetup luksOpen /dev/sda3 dmcrypt_root

There you'll be prompted to enter your password phrase for encrypted drive, type your paranoid password there.

   Warning

The default keymap at boot time is us. If you enter your passphrase using a different keymap, you won't be able to unlock your crypt volume if the passphrase contains any characters that are located elsewere on your keyboard layout that with the us layout.

Create logical volumes

root # pvcreate /dev/mapper/dmcrypt_root
root # vgcreate vg /dev/mapper/dmcrypt_root          
root # lvcreate -L2G --name swap vg
root # lvcreate -l 100%FREE --name root vg

Feel free to specify your desired size by altering the numbers after the -L flag. For example, to make your portage dataset 20GB's, use the flag -L20G instead of -L5G.

   Note

Please, notice that above mentioned partitioning scheme is an example and not a default recommendation, change it accordingly to desired scheme.

Create a filesystem on volumes

root # mkfs.vfat -F 32 /dev/sdc2
root # fatlabel /dev/sdc2 "BOOT"
root # mkswap /dev/mapper/vg-swap
root # mkfs.ext4 /dev/mapper/vg-root

Basic system setup

root # swapon /dev/mapper/vg-swap
root # mkdir /mnt/funtoo
root # mount /dev/mapper/vg-root /mnt/funtoo
root # mkdir  /mnt/funtoo/boot
root # mount /dev/sdc2 /mnt/funtoo/boot

Get Funtoo Gnome

You can pull your Subarches gnome tarball if you wish: 

root # cd /mnt/funtoo
root # wget https://build.funtoo.org/1.4-release-std/x86-64bit/generic_64/gnome-latest.tar.xz
root # tar --numeric-owner --xattrs --xattrs-include='*' -xpf *gnome* && rm -f *gnome*

Load Funtoo

  • expand your run tmpfs to be half of your ram:
root # mount -t tmpfs tmpfs /run
  • mount up:
root # cd /mnt/funtoo && mount -t proc none proc
mount --rbind /sys sys
mount --rbind /dev dev
mount --rbind /run run
  • chroot in:
root # cd /mnt/funtoo && env -i HOME=/root TERM=$TERM chroot . bash -l
  • Set yo password:
  • set yo hostname:
  • set cloudflare dns resolution for installing:
  • Set yo time zone:
root # passwd
root # echo 'hostname="crypto"' > /etc/conf.d/hostname
root # echo "nameserver 1.1.1.1" > /etc/resolv.conf
root # ln -sf /usr/share/zoneinfo/America/Detroit /etc/localtime
  • Deploy your fstab:
root # cat > /etc/fstab << "EOF"
LABEL=BOOT /boot vfat noauto,noatime 1 2
/dev/mapper/vg-swap none swap sw 0 0
/dev/mapper/vg-root / ext4 noatime,nodiratime,defaults 0 1
tmpfs /run tmpfs rw,nodev,nosuid 0 0
EOF
  • compile in ram:
root # echo 'PORTAGE_TMPDIR="/run"' > /etc/portage/make.conf
  • Deploy your package.use file:
root # cat > /etc/portage/package.use << "EOF"
sys-kernel/debian-sources lvm luks
sys-kernel/debian-sources-lts lvm luks
sys-boot/grub device-mapper
sys-fs/lvm2 static-libs
sys-kernel/genkernel cryptsetup
dev-libs/openssl static-libs
dev-libs/json-c static-libs
app-crypt/argon2 static-libs
dev-libs/popt static-libs
sys-fs/cryptsetup static
dev-libs/libgpg-error static-libs
sys-kernel/linux-firmware initramfs
EOF
  • merge stuff:
root # ego sync && emerge grub haveged intel-microcode linux-firmware eix cryptsetup lvm2 debian-sources debian-sources-lts

Bootloader Configuration

better-initramfs

An example /etc/boot.conf for better-initramfs: 

boot {
  generate grub
  default "Funtoo Linux"
  timeout 3
}
"Funtoo Linux" {
  kernel vmlinuz[-v]
  initrd /initramfs.cpio.gz
  params += enc_root=/dev/sda3 lvm luks root=/dev/mapper/vg-root  rootfstype=ext4 resume=swap:/dev/mapper/vg-swap quiet
}

Now, run boot-update to write the configuration files to /boot/grub/grub.cfg

genkernel

Configure the bootloader as described above, with correct kernel and initramfs images names. An example for genkernel and grub2. You will be editing /etc/boot.conf: 

boot {
  generate grub
  default "Funtoo Linux"
  timeout 3
}
"Funtoo Linux" {
  kernel kernel-genkernel-x86_64-3.13.0
  initrd initramfs-genkernel-x86_64-3.13.0
  params += crypt_root=/dev/sda3 dolvm real_root=/dev/mapper/vg-root  rootfstype=ext4 resume=swap:/dev/mapper/vg-swap quiet
}

Final steps

Umount everything, close encrypted drive and reboot 

root # umount -l -v /mnt/funtoo/{dev, proc, home, usr/portage, boot} 
root # vgchange -a n
root # cryptsetup luksClose dmcrypt_root

After reboot you will get the following: 

>>> better-initramfs started. Kernel version 2.6.35-gentoo-r10
>>> Create all the symlinks to /bin/busybox.
>>> Initiating /dev/dir
>>> Getting LVM volumes up (if any)
Reding all physical volumes. This make take awhile...
No volume group found
No volume group found
>>> Opening encrypted partition and mapping to /dev/mapper/dmcrypt_root
Enter passphrase fore /dev/sda2:

Type your password 

>>> Again, getting LVM volumes up (if any, after map dmcrypt).
  Reading all physical volumes.  This may take a while...
  Found volume group "vg" using metadata type lvm2
  4 logical volume(s) in volume group "vg" now active
>>> Mounting rootfs to /newroot
>>> Umounting /sys and /proc.
>>> Switching root to /newroot and executing /sbin/init.
INIT: version 2.88 booting
Loading /libexec/rc/console/keymap
  OpenRC 0.6.1 is starting up Funtoo Linux (x86_64)
...boot messages omitted for clarity
   
orion login: oleg
Password:
Last login: Thu Oct 14 20:49:21 EEST 2010 on tty1
oleg@orion ~ %

management

Change your LUKs-encrypted drive's passphrase

You may want to change your encrypted volume’s passphrase or password from time to time. To do so, run the following commands in the console as root: 

root # cryptsetup luksChangeKey /dev/sda3

You'll be prompted to enter in the existing passphrase first, then to enter in your new passphrase. You will not be asked to confirm your new passphrase, so be careful when running this operation.


Additional links and information

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