[Bug 484102] Re: Grub2 doesn't chainload truecrypt loader correctly

[Attila Lendvai]

so, to sum it up:

1) when installing grub2 it needs/overwrites more then just the first
sector (first 512 bytes, aka the MBR)

2) TC uses the first 64 sectors (its MBR, then some code to decrypt the
system, and some encryption keys)

3) when chainloading a backed up TC MBR from a file using grub2, then it
tries to read sectors 2-64 from the physical driver, which has been
overwritten by grub2


workarounds:

11) install grub2 into a partition (which is not recommended and warns
at install), instead of the MBR, and press ESC at the TC screen to boot
linux

12) boot the TC rescue iso image (IIUC, no one reported this to work)

13) use grub2tc to generate a kernel from the TC rescue iso image (no
reports here that it works, but most probably it does)


possible solutions (? this is just wild speculation):

21) smarten up grub2 chainload, and chainload TC so that the MBR is
ignored and the decryption code, that normally gets loaded/started by
the TC MBR, gets loaded/started by grub2 chainload

22) change grub2 to work from a single MBR sector (as grub1 used to?)

23) add feature to grub2 to hijack the bios routines reading from the
disk in case of a chainloading a file, and read data from the file
instead of the physical disk

24) write/compile a special version of the TC boot loader that assumes
that all the required data is in the memory already.

i think 21) would be the best solution, but again, this is wild
speculation, i lack the required background in grub2/booting/etc.

please, do correct me if my understanding of the issue is wrong!

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https://bugs.launchpad.net/bugs/484102

Title:
  Grub2 doesn't chainload truecrypt loader correctly

Status in “grub2” package in Ubuntu:
  Confirmed

Bug description:
  Binary package hint: grub2

  I am working on a dual-boot system with one hard disk.
  sda1 = /boot
  sda2 = Windows Vista Ultima encrypted with TrueCrypt System Encryption
  sda3 = Ubuntu 9.10 encrypted lvm

  The grub2 entry for windows is created by the file 50_windows in the
  "/etc/grub.d" directory:

  #! /bin/sh -e
  echo "Adding Windows Vista entry" >&2
   cat << EOF
  menuentry "Windows Vista" {
  	set root=(hd0,2)
  	parttool (hd0,2) boot+
  	chainloader (hd0,1)/truecrypt.mbr
  }
  EOF

  Choosing this entry in the grub2 menu the Truecrypt loader only shows the following message: 
  "TrueCrypt Boot Loader
  Load damaged! Use Rescue Disk: Repair > Options > Restore Truecrypt Boot Loader"
  But this would install the Bootloader into the MBR, where grub2 shall be. The TrueCrypt Loader is in /boot/truecrypt.mbr
  Booting Ubuntu works without problems.

  With grub-legacy the chainloading worked.

  The menu.lst:
  title		Windows Vista
  rootnoverify	(hd0,1)
  savedefault
  makeactive
  chainloader	(hd0,0)/truecrypt.mbr

  My Grub2 version: 1.97~beta4

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