Now, less cryptic - Cryptsetup changes in Saucy

Previously, whenever cryptsetup package was installed, its modules and utilities were unconditionally copied into initramfs. Making it quite large.

But there are legitimate use cases of installing cryptsetup, yet not needing it in the initramfs. One only needs cryptsetup in the initramfs if root filesystem or resume devices are encrypted.

I have therefore modified cryptsetup initramfs hooks to only include cryptsetup in the initramfs when necessary. I have tested multiple combinations and here is a small summary:

No cryptsetup in initramfs, when:

no encrypted devices present
non-rootfs filesystems are encrypted (e.g. /var/lib is encrypted)
swap is encrypted with random key file (i.e. non-persistent encrypted swap)

Cryptsetup is in initramfs, when:

rootfs is encrypted ( '/' )
swap is encrypted with a passphrase / key-file (i.e. can unlock & resume from hibernate)
CRYPTSETUP='y' option is specified in /etc/initramfs-tools/initramfs.conf

The last provision is for the case where one wants to generate an initrd on this machine, which will then be transferred to boot something else.

cryptsetup (2:1.4.3-4ubuntu4) saucy; urgency=low

  * debian/initramfs/cryptroot-hook:
    - Do not unconditionally include cryptsetup utils in the initramfs.
    - Do not include any modules or utils in the initramfs, unless
      rootfs/resume devices are encrypted or CRYPTSETUP is set to 'y' in
      the initramfs.conf configuration file.
 -- Dmitrijs Ledkovs Mon, 10 Jun 2013 16:25:46 +0100

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