heads/initrd/bin/seal-key

#!/bin/sh
# This will generate a disk encryption key and seal / ecncrypt
# with the current PCRs and then store it in the TPM NVRAM.
# It will then need to be bundled into initrd that is booted with Qubes.

TPM_INDEX=3
TPM_SIZE=312
KEY_FILE=/tmp/secret.key

. /config

die() {
	echo >&2 "$@";
	rm -f /tmp/secret.key /tmp/recovery.key /tmp/sealed
	exit 1;
}
warn() { echo >&2 "$@"; }

# Key slot 0 is the manual recovery pass phrase
# that they user entered when they installed Qubes,
# key slot 1 is the one that we've generated.
read -s -p "Enter disk recovery key: " disk_password
echo -n "$disk_password" > /tmp/recovery.key
echo

for dev in $CONFIG_QUBES_DEVS; do
	echo "++++++ $dev: Removing old key slot"
	cryptsetup luksKillSlot \
		--key-file /tmp/recovery.key \
		$dev 1 \
	|| warn "$dev: ignoring problem"
done

read -s -p "New disk decryption password for booting: " key_password
echo
read -s -p "Repeat password: " key_password2
echo

if [ "$key_password" != "$key_password2" ]; then
	die "Key passwords do not match"
fi

dd \
	if=/dev/urandom \
	of="$KEY_FILE" \
	bs=1 \
	count=128 \
	2>/dev/null \
|| die "Unable to generate 128 random bytes"

for dev in $CONFIG_QUBES_DEVS; do
	echo "+++++ $dev: Adding key"
	cryptsetup luksAddKey \
		--key-file /tmp/recovery.key \
		--key-slot 1 \
		$dev "$KEY_FILE" \
	|| die "$dev: Unable to add key"
done

# Now that we have setup the new keys, measure the PCRs
/bin/qubes-measure-luks $CONFIG_QUBES_DEVS \
	|| die "Unable to measure the LUKS headers"

# Note that PCR 4 needs to be set with the "normal-boot"
# path value, which we do not have right now since we are
# in a recovery shell.
# PCR 5 must be all zero since no kernel modules should have
# been loaded during a normal boot, but might have been
# loaded in the recovery shell.
# Otherwise use the current values of the PCRs, which will be read
# from the TPM as part of the sealing ("X").
tpm sealfile2 \
	-if "$KEY_FILE" \
	-of /tmp/sealed \
	-pwdd "$key_password" \
	-hk 40000000 \
	-ix 0 X \
	-ix 1 X \
	-ix 2 X \
	-ix 3 X \
	-ix 4 f8fa3b6e32e7c6fe04c366e74636e505b28f3b0d \
	-ix 5 0000000000000000000000000000000000000000 \
	-ix 6 X \
|| die "Unable to seal secret"

rm -f "$KEY_FILE"


# to create an nvram space we need the TPM owner password
# and the TPM physical presence must be asserted.
#
# The permissions are 0 since there is nothing special
# about the sealed file
tpm physicalpresence -s \
|| warn "Warning: Unable to assert physical presence"

read -s -p "TPM Owner password: " tpm_password
echo

tpm nv_definespace \
	-in $TPM_INDEX \
	-sz $TPM_SIZE \
	-pwdo "$tpm_password" \
	-per 0 \
|| warn "Warning: Unable to define NVRAM space; trying anyway"


tpm nv_writevalue \
	-in $TPM_INDEX \
	-if /tmp/sealed \
|| die "Unable to write sealed secret to NVRAM"

rm /tmp/sealed