Re: Support for plain dm-crypt and detached LUKS header

[Mat628]

>I would personally assume that something could be done in the dedicated /etc/grub.d/ directories that would allow grub-mkconfig to function as required without changing anything to it?  

Xen, that is probably possible, but I chose to modify grub-mkconfig_lib.in because that is where the original code to mount a cryptodisk is echoed to grub.cfg.

Unmodified grub-2.02-rc2 grub-mkconfig_lib.in

prepare_grub_to_access_device ()

{

.

.

.

if [ x$GRUB_ENABLE_CRYPTODISK = xy ]; then

      for uuid in `"${grub_probe}" --device $@ --target=cryptodisk_uuid`; do

      echo "cryptomount -u $uuid"

      done

  fi

----------------

"cryptomount -u $uuid" is echoed into grub.cfg as seen below

----------------

menuentry 'Ubuntu GNU/Linux'{

    load_video

    set gfxpayload=keep

    insmod gzio

    insmod part_msdos

    insmod cryptodisk

    insmod luks

    insmod gcry_rijndael

    insmod gcry_rijndael

    insmod gcry_sha1

    insmod lvm

    insmod ext2

    cryptomount -u f804b7d24ec3460aaa45b0bcd8d294ac

    set root='lvmid/mi5iPo-r7rN-RZ5n-oD5M-7UNA-espt-Y5JCrX/

----------------

Now with my modified grub-mkconfig_lib.in it replaces all instances of "cryptomount -u $uuid" with the contents of mattle_opts.cfg by echoing the contents instead of echoing "cryptomount -u $uuid". Now to do the same as above but for a LUKS device with detached header.

mattle_opts.cfg file contents -->

search.pt_uuid 12345678-01 luks_device

search.fs_uuid 1234-5678 usb_with_header_file

cryptomount --header=($usb_with_header_file)/header.bin ($luks_device)

----------------

prepare_grub_to_access_device ()

{

.

.

.

if [ x$GRUB_ENABLE_CRYPTODISK = xy ]; then

      if [ x$GRUB_ENABLE_CRYPTODISK_MATTLE_OPTS = xy ]; then

          .

          .

          .

          if test -f "${prefix}/etc/mattle_opts.cfg"; then

            while read -r WHOLE_FILE; do echo "$WHOLE_FILE" ; done < ${prefix}/etc/mattle_opts.cfg

          else

            gettext_printf "Error: cannot open %s\n" "${prefix}/etc/mattle_opts.cfg" 1>&2

            exit 1

          fi

      else

        for uuid in `"${grub_probe}" --device $@ --target=cryptodisk_uuid`; do

          echo "cryptomount -u $uuid"

        done

      fi

  fi

----------------

grub.cfg

----------------

menuentry 'Ubuntu GNU/Linux' {

    load_video

    set gfxpayload=keep

    insmod gzio

    insmod part_msdos

    insmod cryptodisk

    insmod luks

    insmod gcry_rijndael

    insmod gcry_rijndael

    insmod gcry_sha1

    insmod lvm

    insmod ext2

    search.pt_uuid 12345678-01 luks_device

    search.fs_uuid 1234-5678 usb_with_header_file

    cryptomount --header=($usb_with_header_file)/header.bin ($luks_device)

    set root='lvmid/mi5iPo-r7rN-RZ5n-oD5M-7UNA-espt-Y5JCrX/

----------------

The grub.cfg is the same, including loaded modules, with the only difference from mattle_opts.cfg.