Mounting HDD on PC

Introduction

• The goal is to mount PS3 HDD on PC Linux and make changes to it.
• Use device mapper for transparent encryption/decryption.

Device Mapper

• A really cool feature of Linux 2.6/3.
• The device mapper is stackable.

dm-bswap16

• Swaps bytes in each 16-bit word.
• It is necessray for HDD/VFLASH encryption/decryption.
• Tested on Linux 3.5.3

GIT repo: http://gitorious.ps3dev.net/ps3linux/dm-bswap16

Test

modprobe loop
modprobe dm_mod

insmod ./dm-bswap16.ko

dd if=/dev/zero of=test.bin bs=1K count=100

losetup /dev/loop0 ./test.bin

echo "0 200 bswap16 /dev/loop0" | dmsetup create test

ls -l /dev/mapper/test

echo "00 01 00 01 00 01" | xxd -r -p > /dev/mapper/test

# device mapper target

hexdump -C /dev/mapper/test 
00000000  00 01 00 01 00 01 00 00  00 00 00 00 00 00 00 00  |................|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00019000

# real data, as you see bytes are swapped in each 16-bit word
# device mapper allows you to do really cool things :)

hexdump -C /home/glevand/test.bin
00000000  01 00 01 00 01 00 00 00  00 00 00 00 00 00 00 00  |................|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00019000

dmsetup remove test

Links

• http://linuxgazette.net/114/kapil.html
• http://techgmm.blogspot.de/p/writing-your-own-device-mapper-target.html
• http://www.freeotfe.org/docs/Main/mobile_site/Linux_examples__dm-crypt.htm
• http://www.hopelesscase.com/linuxnotes/encrypted_filesystems/dmsetup_losetup_and_mount