UbuntuHelp:EncryptedFilesystemLVMHowto
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Installing Ubuntu 7.04 on an Encrypted LVM Partition For Root, Swap, and Home
by Nico Gulden
This howto describes the aspects to be noticed installing Ubuntu 7.04 on an encrypted LVM partition. It is based on the howto below written by John Bindel. It gave me the inspiration to try it with Ubuntu 7.04. The steps are basically the same as for Ubuntu 6.06.
First of all, I want to thank John Bindel for the inspiration and Ilkka Tuohela for the right hint to get everything working.
/boot is the only unencrypted partition. The other partitions all reside on one volume group in lvm. The physical volume below the volume group is configured on top an encrypted partition.
Preparation with the live-cd
Follow the steps outline below for Ubuntu 6.06 using the Ubuntu 7.04 desktop install disk. Partition your harddisc using some partition editor, fdisk or System->Administration->Gnome Partition Editor. Make one partition of 100MB for /boot which is sda1 in this example. Create an extended partition for the left space on the disc. Create a logical partition with rest of the created extended partition, sda5 in this example.
For further preparation you'll need a working internet connection. John suggested installing Ubuntu on an unencrypted primary partition. I did all necessary preparation with the live cd. First you'll need to edit your /etc/apt/sources.list and uncomment the universe repository entries, update your package list and install cryptsetup, initramfs-tools, hashalot, lvm2.
You should activate the universe repository in your /etc/apt/sources.list
# sudo aptitude update # sudo aptitude -y install cryptsetup initramfs-tools hashalot lvm2
After installing the needed packages, your are ready for the setup of lvm2 on your hard disk. Before you can start, you need to load the following modules:
# sudo modprobe aes-i586 # sudo modprobe dm-crypt # sudo modprobe dm-mod
Encrypt data partition
From John's Tutorial:
>>> Check the future encrypted LVM physical partition for errors. This will take several minutes for each partition. This fills each partition with pseudorandom data from the not-so-random libc pseudorandom source
# sudo /sbin/badblocks -c 10240 -s -w -t random -v /dev/sda5
Fill the partitions with random data. This may take MANY hours for the large partitions, on average 1.6M/sec of data is written to disk, so a 10GB partition might take around 2 hours, and 100GB partition might take a bit under 20 hours. . The /dev/urandom source is a good source of randomization that should prevent attackers from being able to determine where data actually resides on the encrypted filesystem, which would help them know what they should try to decrypt. The /dev/random source is even better, but it might take hundreds of years to fill the disk from it.
# sudo dd if=/dev/urandom of=/dev/sda5
<<<
In the next step you create the encryption on the logical partition and unlock the partition.
# sudo cryptsetup -y --cipher aes-cbc-essiv:sha256 --key-size 256 luksFormat /dev/sda5 WARNING! ======== This will overwrite data on /dev/sda5 irrevocably. Are you sure? (Type uppercase yes): YES Enter LUKS passphrase: (enter passphrase) Verify passphrase: (repeat passphrase) # sudo cryptsetup luksOpen /dev/sda5 pvcrypt
Create LVM
Create a physical volume and on top of that the volume group with all necessary logical volumes.
# sudo pvcreate /dev/mapper/pvcrypt # sudo vgcreate vg /dev/mapper/pvcrypt # sudo lvcreate -n <lvname> -L <size> vg
Create logical volumes for /usr, /home/, /tmp, /var, /opt, root and swap using the lvcreate command according to the mentioned schema. Make sure you don't use any special characters like underscores or hyphens for the logical volume name. That will generate problems in the later setup.
I got the following setup for my logical volumes.
# sudo lvdisplay -C home vg -wi-ao 10,00G swap vg -wi-ao 512,00M opt vg -wi-ao 200,00M root vg -wi-ao 300,00M tmp vg -wi-ao 200,00M usr vg -wi-ao 4,00G var vg -wi-ao 1,00G
Put a filesystem on each logical volume. Replace <lvname> with each logical volume name you used creating you logical volumes.
# sudo mkswap /dev/mapper/vg-swap # sudo mkfs.ext3 /dev/mapper/vg-<lvname>
Install Ubuntu
Begin the installation of Ubuntu by clicking on the install icon on the desktop of the livecd. Follow the steps in the wizard until step four where it comes to the preparation of the hard disk. Choose manual partitioning, because you already have created all necessary partitions. You just need to map the partitions to the appropriate mount points, choose a filesystem and let the installer create the filesystem. MAKE SURE YOU MAP /dev/sda1 to /boot
The next steps will continue just as an usual installation.
Final preparation
After the installation using the wizard, there are some steps to fulfill in order to let your fresh installed ubuntu come up correctly.
The following steps have to be followed:
- Mount partitions & chroot
- Install missing software to fresh installed ubuntu
- Customize /etc/crypttab, /etc/fstab, /boot/grub/menu.lst
- Rebuild ramdisk
Mount Partitions & chroot
# cd /mnt # sudo mkdir root # sudo mount -t ext3 /dev/mapper/vg-root /mnt/root # sudo mount -t ext3 /dev/sda1 /mnt/root/boot # sudo mount -t ext3 /dev/mapper/vg-home /mnt/root/home # sudo mount -t ext3 /dev/mapper/vg-opt /mnt/root/opt # sudo mount -t ext3 /dev/mapper/vg-usr /mnt/root/usr # sudo mount -t ext3 /dev/mapper/vg-var /mnt/root/var # sudo mount -t ext3 /dev/mapper/vg-tmp /mnt/root/tmp
Chroot
# sudo chroot /mnt/root #(chroot) sudo mount -t proc proc /proc #(chroot) sudo mount -t sysfs sys /sys
Install missing software
#(chroot) sudo aptitude update #(chroot) sudo aptitude install cryptsetup hashalot initramfs-tools lvm2
Customize files
Edit /etc/crypttab and enter the following line.
# <target name> <source device> <key file> <options> pvcrypt /dev/sda5 none luks,retry=1,lvm=vg
You recognize the target name and the source device name. It comes from the cryptsetup luksOpen /dev/sda5 pvcrypt command. With the options you tell cryptsetup that it shall use the volume group name vg in this example.
According to the example your /etc/fstab should look like this
# /etc/fstab: static file system information. # # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc defaults 0 0 /dev/mapper/vg-root / ext3 defaults,errors=remount-ro 0 1 /dev/sda1 /boot ext3 defaults 0 2 /dev/mapper/vg-home /home ext3 defaults 0 2 /dev/mapper/vg-opt /opt ext3 defaults 0 2 /dev/mapper/vg-tmp /tmp ext3 defaults 0 2 /dev/mapper/vg-usr /usr ext3 defaults 0 2 /dev/mapper/vg-var /var ext3 defaults 0 2 /dev/mapper/vg-swap none swap sw 0 0 /dev/scd0 /media/cdrom0 udf,iso9660 user,noauto 0 0 /dev/fd0 /media/floppy0 auto rw,user,noauto 0 0
Your /boot/grub/menu.lst should have the following or similar entry
title Ubuntu root (hd0,0) kernel /vmlinuz-2.6.20-16-generic root=/dev/mapper/vg-root ro quiet initrd /initrd.img-2.6.20-16-generic quiet savedefault
Rebuild ramdisk
Edit the file /etc/initramfs-tools/modules to make sure the correct modules are included in the ramdisk
aes-i586 dm-crypt dm-mod sha256
Run the following command to rebuild the ramdisk.
# sudo update-initramfs -k all -c
After building the ramdisk it should be checked.
#(chroot) cd /tmp #(chroot) sudo mkdir foo #(chroot) cd foo/ #(chroot) sudo zcat /boot/initrd.img-$(uname -r)|cpio -iv #(chroot) sudo cat /tmp/foo/conf/conf.d/cryptroot
If initramfs-cryptsetup did not understand the setup, the /tmp/foo/conf/conf.d/cryptroot file is completely missing and it does not make even sense to try booting. The lvm lines here are just names it expects to be available after setup and really don't matter in your case.
If everything went fine and the /tmp/foo/conf/conf.d/cryptroot is present you should give a try and reboot. Right at the beginning of the boot process you should be asked for the physical volume password.
Booting fails
If booting fails and you need to rebuild the ramdisk or fix some configuration files, follow these steps. I assume you know the details, therefore they are just outline.
- Boot the ubuntu live cd
- Uncomment the universe repository in the sources.list, update the package list and install cryptsetup, initramfs-tools, hashalot, lvm2
- modprobe the modules aes-i586, dm-crypt and dm-mod
- Unlock the physical volume: cryptsetup luksOpen /dev/sda5 pvcrypt
- Detect the logical volume: vgscan; vgchange -a y vg
- Mount the partitions to /mnt/root
- Chroot into /mnt/root and mount proc and sysfs
- Make your changes
Some Notes
- Suspend or suspend2 don't work with this configuration. If you have a working configuration with suspend or suspend2, please append to this article or post a separate one. There might be some people out there looking for it. Thanks.
Installing Ubuntu 6.06 on an Encrypted LVM Partition For Root, Swap, and Home
by John Bindel ([email protected])
This how-to explains the process of installing Ubuntu 6.06 on an encrypted LVM partition. One encrypted physical partition is used, and the logical volume manager is used to manage the operating system volumes. Only /boot is unencrypted.
Install
Boot the Ubuntu 6.06 desktop install disk.
Partition the disk with System->Administration->Gnome Partition Editor
Make 3GB ext3 primary partition (See NOTES at the bottom if you want to save room and use the server version, which only needs 600 MB). Make an extended partition with the rest. Make an ext3 logical partition of 200MB for /boot which is sda5 in this example. Make an ext3 logical parition with the rest as sda6. Click "apply" and then close the tool. It would be nice to install directly to encrypted LVM volumes, but the desktop installer does not seem to be capable of that. It fails after the manual paritioning step when I have tried.
Double-click on "Install".
Choose to manually edit partitions. Make no changes to partitions and click "forward". Set /dev/sda5 as the /boot mount point and /dev/sda1 as the "/" mount point. Clear all other mount points. Select reformat on these two and click "forward". Then click "install".
Click "continue" when asked about not having a swap partition. We'll add one later.
Let the system install and then reboot.
Open a terminal and get root.
$ sudo bash
Add "universe" repositories by uncommenting lines in /etc/apt/sources.list.
Install the cryptsetup, hashalot, and initramfs-tools packages.
# apt-get update # apt-get install cryptsetup hashalot initramfs-tools
Build an initrd image
Load the modules that will be needed.
# modprobe dm_crypt # modprobe aes_i586 # modprobe sha256
Add the following line to /etc/kernel-img.conf:
ramdisk = /usr/sbin/mkinitramfs
Add the following lines to /etc/mkinitramfs/modules:
dm_mod dm_crypt sha256 aes_i586
Create file /etc/mkinitramfs/hooks/pvcrypt. This script is executed when the init ramdisk image is built.
#!/bin/sh
PREREQ=""
prereqs()
{
echo "$PREREQ"
}
case $1 in
prereqs)
prereqs
exit 0
;;
esac
if [ ! -x /sbin/cryptsetup ]; then
exit 0
fi
. /usr/share/initramfs-tools/hook-functions
mkdir ${DESTDIR}/etc/console
cp /etc/console/boottime.kmap.gz ${DESTDIR}/etc/console
copy_exec /bin/loadkeys /bin
copy_exec /usr/bin/chvt /bin
copy_exec /sbin/cryptsetup /sbin
Create file /etc/mkinitramfs/scripts/local-top/pvcrypt. This script is executed during the init bootup.
#!/bin/sh
PREREQ="udev"
prereqs()
{
echo "$PREREQ"
}
case $1 in
# get pre-requisites
prereqs)
prereqs
exit 0
;;
esac
/bin/loadkeys /etc/console/boottime.kmap.gz
modprobe -Qb dm_crypt
modprobe -Qb aes_i586
modprobe -Qb sha256
if grep -q splash /proc/cmdline; then
/bin/chvt 1
fi
/sbin/cryptsetup luksOpen /dev/sda6 pvcrypt
if grep -q splash /proc/cmdline; then
/sbin/usplash -c &
sleep 1
fi
Make these scripts executable by root.
# chmod +x /etc/mkinitramfs/hooks/pvcrypt # chmod +x /etc/mkinitramfs/scripts/local-top/pvcrypt
Now build a new initrd image:
# update-initramfs -u ALL
Encrypt the data partition
Check the future encrypted LVM physical partition for errors. This will take several minutes for each partition. This fills each partition with pseudorandom data from the not-so-random libc pseudorandom sourc
# /sbin/badblocks -c 10240 -s -w -t random -v /dev/sda6
Fill the partitions with random data. This may take 4 hours for the large partition. The /dev/urandom source is a good source of randomization that should prevent attackers from being able to determine where data actually resides on the encrypted filesystem, which would help them know what they should try to decrypt. The /dev/random source is even better, but it might take hundreds of years to fill the disk from it.
# dd if=/dev/urandom of=/dev/sda6
Create the encryption key for the partition.
# cryptsetup --verify-passphrase --verbose --hash=sha256 --cipher=aes-cbc-essiv:sha256 --key-size=256 luksFormat /dev/sda6 # cryptsetup luksOpen /dev/sda6 pvcrypt
Make an LVM physical volume, volume group, and logical volumes on the encrypted partition. The size of 9938 happens to be how much is left on my logical partition.
# pvcreate /dev/mapper/pvcrypt Physical volume "/dev/mapper/pvcrypt" successfully created # vgcreate vgcrypt /dev/mapper/pvcrypt Volume group "vgcrypt" successfully created # lvcreate -n lvroot -L 8G vgcrypt Logical volume "lvroot" created # lvcreate -n lvswap -L 1G vgcrypt Logical volume "lvswap" created # lvcreate -n lvhome -l 9938 vgcrypt Logical volume "lvhome" created
Put a filesystem on each volume.
# mkfs.ext3 /dev/mapper/vgcrypt-lvroot # mkfs.ext3 /dev/mapper/vgcrypt-lvhome # mkswap /dev/mapper/vgcrypt-lvswap
Populate the encrypted volumes.
# mkdir /mnt/root # mkdir /mnt/home # mount /dev/mapper/vgcrypt-lvroot /mnt/root # mount /dev/mapper/vgcrypt-lvhome /mnt/home # cp -ax / /mnt/root # rm -rf /mnt/root/home/* # cp -ax /home/* /mnt/home
Edit /mnt/root/etc/fstab. First change this line
/dev/sda1 / ext3 defaults,errors=remount-ro 0 1
to
/dev/mapper/vgcrypt-lvroot / ext3 defaults,errors=remount-ro 0 1
And add these lines:
/dev/mapper/vgcrypt-lvhome /home ext3 defaults 0 1 /dev/mapper/vgcrypt-lvswap none swap sw 0 0
Add this to the bottom of /boot/grub/menu.lst. (hd0,4) refers to the boot partition, /dev/sda5.
title Cryptotest root (hd0,4) kernel /vmlinuz-<your kernel version here> root=/dev/mapper/vgcrypt-lvroot ro initrd /initrd.img-<your kernel version here> savedefault boot
Check the kernel version with uname -r. For example, it may be "2.6.15-26-server".
Reboot to test by typing sudo reboot. Press ESC to enter the GRUB
menu and select Cryptotest. The boot process will stop waiting for
the encrypted partition's passphrase. The prompt will probably be
hard to see because of a lot of debugging information on the console.
If all goes well, then continue. Otherwise seek help or figure out what went wrong.
Edit /boot/grub/menu.lst to remove the lines we added at the end, and change the line that has
# kopt=root=/dev/sda1 ro
to
# kopt=root=/dev/mapper/vgcrypt-lvroot ro
Then run
$sudo update-grub
Finally make a backup key file for unencrypting the drive. Insert a
blank USB thumb drive.
$ sudo dd if=/dev/random of=/media/<usbdrive>/pvcrypt-$(whoami)-key bs=1 count=256 $ sudo cryptsetup luksAddKey /dev/sda6 /media/<usbdrive>/pvcrypt-$(whomai)-key
Wipe the old partition.
# /sbin/badblocks -c 10240 -s -w -t random -v /dev/sda1
Notes
Those who do not want a large leftover partition on sda1 can make one as small as 600MB and install the server version of Ubuntu instead, or even make the /boot partition 600MB and just install the root partition there initially.
Gnome will popup a notice that it has found an encrypted partition. Cancel the dialog. It seems that /sbin/partprobe causes this dialog to popup. Any advice on getting rid of this would be appreciated.
