README

README (text/plain), 9.90 KB, created by Alon Bar-Lev (RETIRED) on 2005-06-11 12:39:17 UTC

suspend2+encrypted swap+encrypted root
----------------------------------------------------
The mission is to create an encrypted system using suspend2 that is encrypted
also when suspended.

I want to thank Nigel Cunningham who made suspend2 available!
And to Jary Ruusu who made loop-aes available!

The following instructs how to making it work and check if the unencrypted
boot partition was changed, so that you know that computer is compromised.

I hope you will find this information useful
Alon Bar-Lev

Components
------------------
- suspend2 from http://www.suspend2.net needed for suspending.
- loop-aes from http://sourceforge.net/projects/loop-aes/ needed to encrypt 
  a disk on-the-fly.
- aespipe from http://sourceforge.net/projects/loop-aes/ needed to 
  encrypt/decrypt partition.
- gpg from http://www.gnupg.org/ needed to handle keys.
- perl Digest-SHA1
- genkernel from http://www.gentoo.org needed to build kernel+initrd (optional)
- splashutils from http://www.gentoo.org needed if you like to use splash util

[gentoo]
app-crypt/gnupg	
	-> but you should compile it static manual, no use
dev-perl/Digest-SHA1
sys-kernel/genkernel
media-gfx/splashutils
sys-fs/loop-aes (USE: keyscrub)
	-> but you should add ebuild for version 3.0c
app-crypt/aespipe (USE: static)
	-> but you should add ebuild for version 2.3b
sys-apps/util-linux (USE: crypt static)
	-> but you should add q patch from loop-aes
	   (sys-apps/util-linux-2.12q-r1)

Prerequisites
------------------
- I assume you know how to compile utilities in static mode.
- I assume you know how to create initrd.
- Make sure you have a working initrd and that you control the linuxrc script.
- Make sure you have a working suspend2 environment.
- Make sure you have a working loop-aes environment, test loop on files.
- Generate gpg keys to be used to encrypt your disk.
- Compile gpg, losetup, aespipe as static.
- BACKUP YOUR SYSTEM!!!

Partitions
------------------
In order to have encrypted root and encrypted swap you need to have at least
three partitions on disk.
- boot partition
	unencrypted boot partition, used to hold kernel,
	initrd, utilities and keyfile. Should be none journal type.
- swap partition
	encrypted swap partition, used for suspending and resuming.
	Should be at least the size of RAM (-compress).
- root partition
	encrypted root partition, your data may be stored here.

Through out this document the following partitions are used, you should
replace them with your own:
/dev/hda1 - boot
/dev/hda2 - swap
/dev/hda3 - root


Boot partition
------------------
Create the following tree in the boot partition

+ /
  + boot-util
  | + `uname -r`	<-- allows to use more than one kernel
  |   + -etc
  |   | - splash	<-- boot splash files
  |   + bin
  |   | - gpg.static
  |   | - gpg -> gpg.static
  |   | - losetup.q.static
  |   | - losetup.q -> losetup.static
  |   | - aespipe.static
  |   | - aespipe -> aespipe.static
  |   | - splash_util.static
  |   | - splash_util -> splash_util.static
  |   + lib
  |     + modules
  |       + `uname -r`
  |         + block
  |           - loop.ko
  - keyfile.gpg		<-- your keys goes into here
  - kernel		<-- your kernel
  - initrd		<-- your initrd

I use two version of a kernel one for testing and one for production,
each have a unique name. If you have encrypted root partition it is most
important to do so, since if you make your kernel unbootable or modules
misplaced, it is very difficult to recover.
losetup patch for loop-aes must be called losetup.q in order to not conflict 
with busybox's losetup.

Root partition
------------------
Since loop device is loaded during initrd, initrd cannot be released.
You must create /initrd in you root partition so initrd will remount there.

Boot utilities
------------------
Attached are several utilities
- mygenkernel
	used in order to generate my kernels (for gentoo system)
	the whole process uses files on encrypted partition so modifications to
	unencrypted partition will not affect.
- mygenkernel-commit
	used in order to commit debug kernel and compile a production kernel.
- mygenkernel.conf
	configuration.
- digest-dir
	used in order to calculate a digest of all files in a specific 
	directory.
	should be executed during startup or after resume.
- mark-boot-digest
	mark current /boot partition digest as base.
- check-boot-digest
	check current boot digest against base.
- check-boot-digest-service
	execute check-boot-digest as gentoo service


Put in /usr/local/share/boot-scripts
Run create-links so that links will be created.

Compile your kernel
---------------------
- Compile your kernel with suspend2 support, initrd support and NO loop device
  module.
- Create initrd with the attached linuxrc script.
- Compile loop-aes module

[gentoo]

Copy default sys-kernel/gentoo-sources into new ebuild 
(eg. gentoo_suspend2_test-sources-2.6.11-r9.ebuild) and modify so suspend2
will be merged.

[..snip..]
-inherit kernel-2
+inherit kernel-2 eutils
[..snip..]
+SUSPEND2_VERSION="2.1.9"
+SUSPEND2_TARGET="${PV/_/-}"
+SUSPEND2_SRC="software-suspend-${SUSPEND2_VERSION}-for-${SUSPEND2_TARGET}"
+SUSPEND2_URI="http://www.suspend2.net/downloads/all/${SUSPEND2_SRC}.tar.bz2"
[..snip..]
-SRC_URI="${KERNEL_URI} ${GPV_SRC} ${ARCH_URI}"
+SRC_URI="${KERNEL_URI} ${GPV_SRC} ${ARCH_URI} ${SUSPEND2_URI}"
[..snip..]
+src_unpack() {
+       kernel-2_src_unpack
+
+       cd ${WORKDIR}
+       unpack ${SUSPEND2_SRC}.tar.bz2
+
+       cd ${S}
+       EPATCH_EXCLUDE="apply unapply ToDo" \
+       EPATCH_FORCE="yes" \
+       EPATCH_SUFFIX="" \
+       EPATCH_OPTS="-p1" \
+       epatch ${WORKDIR}/${SUSPEND2_SRC}
+}
[snip]


You need to enable stty of busybox, change configuration at:
/usr/share/genkernel/@@ARCH@@/busy-config
-# CONFIG_STTY is not set
+CONFIG_STTY=y

Remove /usr/share/genkernel/pkg/@@ARCH@@/busybox-*

Now use genkernel or mygenkernel to create your initrd.

Boot partition
----------------------------
Put gpg keys at /keyfile.gpg file or link exists on boot partition
Create boot partition boot-util as described above.
Put loop module under boot-util/`uname -r`/lib/modules/`uname -r`/block

[gentoo]
You can use mygenkernel that takes boot-util from cache on root file system
and put it in boot file system.

initrd kernel parameters
----------------------------
- initrd_util=/dev/hdaX - location of the boot partition.
- initrd_loops=/dev/hdaX,/dev/hdaY,... - devices to loop over.
- initrd_loopstart=N - first loop index
- initrd_shell=N	(0-none,1-on start,2-after setup,3-after loop)
- root=anything but /dev/ramX since suspend2 will not resume

Example:
initrd_util=/dev/hda1 initrd_loops=/dev/hda2,/dev/hda3 initrd_loopstart=4 initrd_shell=0
This will load utilities from /dev/hda1 and map:
- /dev/loop4->/dev/hda2
- /dev/loop5->/dev/hda3

Expected busybox applets for initrd
---------------------------------------
If you create your own initrd, please make sure the following commands are
available:
- echo
- cp
- cat
- sh
- test
- [
- dd
- sed
- mount
- umount
- mknod
- stty
- mkdir
- ln
- modprobe

/etc/fstab
------------------
Here is my example of fstab, suspend will be written to /dev/loop4

/dev/hda1		/boot		ext2		defaults,noatime	1 2
/dev/loop5		/		ext3		noatime			0 1
/dev/loop4		none		swap		sw			0 0

Encrypting your root partition
-----------------------------------
Setup /etc/fstab to map loop device or root.
Boot your kernel with my initrd and the following arguments:
root=/dev/hda3 initrd_util=/dev/hda1 initrd_shell=2

You should get a shell after initrd was setup correctly.

Set console as tty (required for asepipe)
rm /dev/tty
ln -s /dev/console /dev/tty

Run aespipe
busybox dd if=/dev/hda3 bs=64k | \
	aespipe -G / -K /mnt/keyfile.gpg -e AES256 | \
	busybox dd of=/dev/hda3 conv=notrunc

Reboot your kernel, now put the following arguments:
root=/dev/loop5 initrd_util=/dev/hda1 initrd_loops=/dev/hda3 initrd_loopstart=5 initrd_shell=0

You should be prompted with password for the gpg file and boot should succeed.

Encrypting swap partition
-----------------------------------
Reboot your kernel, now put the following arguments:
root=/dev/loop5 initrd_util=/dev/hda1 initrd_loops=/dev/hda2,/dev/hda3 initrd_loopstart=4 initrd_shell=0 resume2=/dev/hda2

You should be prompted with password for the gpg file and boot should succeed.

After boot create swap file:
mkswap /dev/loop4
swapon -a

Update hibernate.conf
------------------------
This will execute boot partition digest check

OnResume 00 /usr/local/bin/check-boot-digest

This will unmount boot partition so it can be mounted during boot by initrd
Unmount /boot
Mount /boot

Grub
--------
Here is my grub file

default 0
timeout 30
splashimage=(hd0,0)/grub/splash.xpm.gz

title=initrd-2.6.11-gentoo_suspend2_test-r9
root (hd0,0)
kernel (hd0,0)/kernel-2.6.11-gentoo_suspend2_test-r9 root=/dev/loop5 ro resume2=swap:/dev/loop4 video=vesafb:ywrap,mtrr,1400x1050-32@60 splash=silent,theme:gentoo initrd_util=/dev/hda1 initrd_loops=/dev/hda2,/dev/hda3 initrd_loopstart=4 initrd_shell=0
initrd (hd0,0)/initrd-2.6.11-gentoo_suspend2_test-r9
boot


title=initrd-2.6.11-gentoo_suspend2-r9
root (hd0,0)
kernel (hd0,0)/kernel-2.6.11-gentoo_suspend2-r9 root=/dev/loop5 ro resume2=swap:/dev/loop4 video=vesafb:ywrap,mtrr,1400x1050-32@60 splash=silent,theme:gentoo initrd_util=/dev/hda1 initrd_loops=/dev/hda2,/dev/hda3 initrd_loopstart=4 initrd_shell=0
initrd (hd0,0)/initrd-2.6.11-gentoo_suspend2-r9
boot

Digesting boot
--------------------
After you finish all modifications mark current boot digest by:
mark-boot-digest

So that you know if someone has tempered your unencrypted root.

Test suspend2
-------------------
Now try to hibernate...
Good luck!

Open issues
-------------------
There is no known way to protect against sophisticated kernel attach on the
unencrypted boot partition that will cause the hash check to succeed but will 
write your password on a location of the disk.
For now the only way to detect this is to digest the boot partition and 
compare it to one stored on the encrypted file system.

What next
-------------------
I will provide a solution to put gpg keys on PKCS#11 smartcard token.