Mounting FDE ext4 filesystem within fastboot

[tborealis]

I'm working on a FDE provision, using the new IDP provisioner. Part of my requirement is to push a few device specific files into the root filesystem during the provisioning process.

I haven't had much success and am a bit stuck. I'm using a post-flash hook on the idp-provisioner to do the following:

FASTBOOT_SPEC="$1"
STORAGE="$3"
fastboot -s "${FASTBOOT_SPEC}" oem cryptopen "${STORAGE}p2" cryptroot # OKAY
fastboot -s "${FASTBOOT_SPEC}" oem mount "/dev/mapper/cryptroot" "/mnt/my-rootfs" ext4 # Invalid argument

# stage and push the files

I'm a stuck at this point. I can't see any further diagnostics. The only return from the mount is "Invalid argument". It looks like the decryption worked, why can't I mount the FS?

[tdewey-rpi]

When you provision with IDP, we write a partition table into the LUKS container. So, your path isn't /dev/mapper/cryptroot, and you don't need to write /dev/mapper/ (Fastboot will find it for you, to save typing!), you want something like:

fastboot oem cryptopen "${STORAGE}p2" cryptroot
# INFO: cryptopen: partitioned LUKS container; mount an inner block device
# INFO:   /dev/mapper/cryptroot1
# INFO:   /dev/mapper/cryptroot2
fastboot oem mount cryptroot2 /mnt/my-rootfs ext4