heads/initrd/bin/kexec-seal-key

#!/bin/bash
# This will generate a disk encryption key and seal / encrypt
# with the current PCRs and then store it in the TPM NVRAM.
# It will then need to be bundled into initrd that is booted.
set -e -o pipefail
. /etc/functions

find_drk_key_slot() {
	local temp_drk_key_slot=""
	local keyslot

	for keyslot in "${luks_used_keyslots[@]}"; do
		if [ -z "$temp_drk_key_slot" ]; then
			DEBUG "Testing LUKS key slot $keyslot against $DISK_RECOVERY_KEY_FILE for Disk Recovery Key slot..."
			if DO_WITH_DEBUG cryptsetup open --test-passphrase --key-slot "$keyslot" --key-file "$DISK_RECOVERY_KEY_FILE" "$dev"; then
				temp_drk_key_slot="$keyslot"
				DEBUG "Disk Recovery key slot is $temp_drk_key_slot"
				break
			fi
		fi
	done

	echo "$temp_drk_key_slot"
}

TPM_INDEX=3
TPM_SIZE=312
DUK_KEY_FILE="/tmp/secret/secret.key"
TPM_SEALED="/tmp/secret/secret.sealed"
DISK_RECOVERY_KEY_FILE="/tmp/secret/recovery.key"

. /etc/functions
. /tmp/config

TRACE_FUNC

paramsdir=$1
if [ -z "$paramsdir" ]; then
	die "Usage $0 /boot"
fi

KEY_DEVICES="$paramsdir/kexec_key_devices.txt"
KEY_LVM="$paramsdir/kexec_key_lvm.txt"
key_devices=$(cat "$KEY_DEVICES" | cut -d\  -f1 | tr '\n' ' ')

if [ ! -r "$KEY_DEVICES" ]; then
	die "No devices defined for disk encryption"
else
	DEBUG "Devices defined for disk encryption: $key_devices"
fi

if [ -r "$KEY_LVM" ]; then
	# Activate the LVM volume group
	VOLUME_GROUP=$(cat $KEY_LVM)
	if [ -z "$VOLUME_GROUP" ]; then
		die "No LVM volume group defined for activation"
	fi
	lvm vgchange -a y $VOLUME_GROUP ||
		die "$VOLUME_GROUP: unable to activate volume group"
else
	DEBUG "No LVM volume group defined for activation"
fi

DEBUG "$(pcrs)"


luks_drk_passphrase_valid=0
for dev in $key_devices	; do
	attempts=0
	while [ $attempts -lt 3 ]; do
		if [ "$luks_drk_passphrase_valid" == "0" ]; then
			# Ask for the passphrase only once
			read -s -p "Enter LUKS Disk Recovery Key (DRK) passphrase that can unlock: $key_devices: " disk_recovery_key_passphrase
			#Using he provided passphrase as the DRK "keyfile" for unattended operations
			echo -n "$disk_recovery_key_passphrase" >"$DISK_RECOVERY_KEY_FILE"
			echo
		fi

		DEBUG "Testing $DISK_RECOVERY_KEY_FILE keyfile created from provided passphrase against $dev individual key slots"
		if cryptsetup open $dev --test-passphrase --key-file "$DISK_RECOVERY_KEY_FILE" >/dev/null 2>&1; then
			echo "++++++ $dev: LUKS device unlocked successfully with the DRK passphrase"
			luks_drk_passphrase_valid=1
			break
		else
			attempts=$((attempts + 1))
			if [ "$attempts" == "3" ] && [ "$luks_drk_passphrase_valid" == "0" ]; then
				die "Failed to unlock LUKS device $dev with the provided passphrase. Exiting..."
			elif [ "$attempts" != "3" ] && [ "$luks_drk_passphrase_valid" == "1" ]; then
				#We failed unlocking with DRK passphrase another LUKS container
				die "LUKS device $key_devices cannot all be unlocked with same passphrase. Please make $key_devices devices unlockable with the same passphrase. Exiting"
			else
				warn "Failed to unlock LUKS device $dev with the provided passphrase. Please try again."
			fi
		fi
	done
done

attempts=0
while [ $attempts -lt 3 ]; do
	read -s -p "New LUKS TPM Disk Unlock Key (DUK) passphrase for booting: " key_password
	echo
	read -s -p "Repeat LUKS TPM Disk Unlock Key (DUK) passphrase for booting: " key_password2
	echo
	if [ "$key_password" != "$key_password2" ]; then
		attempts=$((attempts + 1))
		if [ "$attempts" == "3" ]; then
			die "Disk Unlock Key (DUK) passphrases do not match. Exiting..."
		else
			warn "Disk Unlock Key (DUK) passphrases do not match. Please try again."
		fi
	else
		break
	fi
done

# Generate key file
echo "++++++ Generating new randomized 128 bytes key file that will be sealed/unsealed by LUKS TPM Disk Unlock Key passphrase"
dd \
	if=/dev/urandom \
	of="$DUK_KEY_FILE" \
	bs=1 \
	count=128 \
	2>/dev/null ||
	die "Unable to generate 128 random bytes"

previous_luks_header_version=0
for dev in $key_devices; do
	# Check and store LUKS version of the devices to be used later
	luks_version=$(cryptsetup luksDump "$dev" | grep "Version" | cut -d: -f2 | tr -d '[:space:]')
	if [ "$luks_version" == "2" ] && [ "$previous_luks_header_version" == "1" ]; then
		die "$dev: LUKSv2 device detected while LUKSv1 device was detected previously. Exiting..."
	fi

	if [ "$luks_version" == "1" ] && [ "$previous_luks_header_version" == "2" ]; then
		die "$dev: LUKSv1 device detected while LUKSv2 device was detected previously. Exiting..."
	fi

	if [ "$luks_version" == "2" ]; then
		# LUKSv2 last key slot is 31
		duk_keyslot=31
		regex="^\s+([0-9]+):\s*luks2"
		sed_command="s/^\s\+\([0-9]\+\):\s*luks2/\1/g"
		previous_luks_header_version=2
		DEBUG "$dev: LUKSv2 device detected"
	elif [ "$luks_version" == "1" ]; then
		# LUKSv1 last key slot is 7
		duk_keyslot=7
		regex="Key Slot ([0-9]+): ENABLED"
		sed_command='s/Key Slot \([0-9]\+\): ENABLED/\1/'
		previous_luks_header_version=1
		DEBUG "$dev: LUKSv1 device detected"
	else
		die "$dev: Unsupported LUKS version $luks_version"
	fi

	# drk_key_slot will be the slot number where the passphrase was tested against as valid. We will keep that slot
	drk_key_slot="-1"

	# Get all the key slots that are used on $dev
	luks_used_keyslots=($(cryptsetup luksDump "$dev" | grep -E "$regex" | sed "$sed_command"))
	DEBUG "$dev LUKS key slots: ${luks_used_keyslots[*]}"
	
	#Find the key slot that can be unlocked with the provided passphrase
	drk_key_slot=$(find_drk_key_slot)

	# If we didn't find the DRK key slot, we exit (this should never happen)
	if [ "$drk_key_slot" == "-1" ]; then
		die "$dev: Unable to find a key slot that can be unlocked with provided passphrase. Exiting..."
	fi

	# If the key slot is not the expected DUK or DRK key slot, we will ask the user to confirm the wipe
	for keyslot in "${luks_used_keyslots[@]}"; do
		if [ "$keyslot" != "$drk_key_slot" ]; then
			#set wipe_desired to no by default
			wipe_desired="no"

			if [ "$keyslot" != "$drk_key_slot" ] && [ "$keyslot" == "1" ]; then
				wipe_desired="yes"
				DEBUG "LUKS key slot $keyslot not DRK. Will wipe this DUK key slot silently"
			elif [ "$keyslot" != "$drk_key_slot" ] && [ "$keyslot" != "$duk_keyslot" ]; then
				# Heads expects key slot LUKSv1:7 or LUKSv2:31 to be used for TPM DUK setup.
				#  Ask user to confirm otherwise
				warn "LUKS key slot $keyslot is not typical ($duk_keyslot expected) for TPM Disk Unlock Key setup"
				read -p "Are you sure you want to wipe it? [y/N] " -n 1 -r
				echo
				# If user does not confirm, skip this slot
				if [[ $REPLY =~ ^[Yy]$ ]]; then
					wipe_desired="yes"
				fi
			elif [ "$keyslot" == "$duk_keyslot" ]; then
				# If key slot is the expected DUK keyslot, we wipe it silently
				DEBUG "LUKS key slot $keyslot is the expected DUK key slot. Will wipe this DUK key slot silently"
				wipe_desired="yes"
			fi

			if [ "$wipe_desired" == "yes" ] && [ "$keyslot" != "$drk_key_slot" ]; then
				echo "++++++ $dev: Wiping LUKS key slot $keyslot"
				DO_WITH_DEBUG cryptsetup luksKillSlot \
					--key-file "$DISK_RECOVERY_KEY_FILE" \
					$dev $keyslot ||
					warn "$dev: removal of LUKS slot $keyslot failed: Continuing"
			fi
		fi
	done


	echo "++++++ $dev: Adding LUKS TPM Disk Unlock Key to LUKS key slot $duk_keyslot"
	DO_WITH_DEBUG cryptsetup luksAddKey \
		--key-file "$DISK_RECOVERY_KEY_FILE" \
		--new-key-slot $duk_keyslot \
		$dev "$DUK_KEY_FILE" ||
		die "$dev: Unable to add LUKS TPM Disk Unlock Key to LUKS key slot $duk_keyslot"
done

# Now that we have setup the new keys, measure the PCRs
# We don't care what ends up in PCR 6; we just want
# to get the /tmp/luksDump.txt file.  We use PCR16
# since it should still be zero
echo "$key_devices" | xargs /bin/qubes-measure-luks ||
	die "Unable to measure the LUKS headers"

pcrf="/tmp/secret/pcrf.bin"
tpmr pcrread 0 "$pcrf"
tpmr pcrread -a 1 "$pcrf"
tpmr pcrread -a 2 "$pcrf"
tpmr pcrread -a 3 "$pcrf"
# Note that PCR 4 needs to be set with the "normal-boot" path value, read it from event log.
tpmr calcfuturepcr 4 >>"$pcrf"
if [ "$CONFIG_USER_USB_KEYBOARD" = "y" -o -r /lib/modules/libata.ko -o -x /bin/hotp_verification ]; then
	DEBUG "Sealing LUKS TPM Disk Unlock Key with PCR5 involvement (additional kernel modules are loaded per board config)..."
	# Here, we take pcr 5 into consideration if modules are expected to be measured+loaded
	tpmr pcrread -a 5 "$pcrf"
else
	DEBUG "Sealing LUKS TPM Disk Unlock Key with PCR5=0 (NO additional kernel modules are loaded per board config)..."
	#no kernel modules are expected to be measured+loaded
	tpmr calcfuturepcr 5 >>"$pcrf"
fi
# Precompute the value for pcr 6
DEBUG "Precomputing TPM future value for PCR6 sealing/unsealing of LUKS TPM Disk Unlock Key..."
tpmr calcfuturepcr 6 "/tmp/luksDump.txt" >>"$pcrf"
# We take into consideration user files in cbfs
tpmr pcrread -a 7 "$pcrf"

DO_WITH_DEBUG --mask-position 7 \
	tpmr seal "$DUK_KEY_FILE" "$TPM_INDEX" 0,1,2,3,4,5,6,7 "$pcrf" \
	"$TPM_SIZE" "$key_password" || die "Unable to write LUKS TPM Disk Unlock Key to NVRAM"

# should be okay if this fails
shred -n 10 -z -u "$pcrf" 2>/dev/null ||
	warn "Failed to delete pcrf file - continuing"
shred -n 10 -z -u "$DUK_KEY_FILE" 2>/dev/null ||
	warn "Failed to delete key file - continuing"

mount -o rw,remount $paramsdir || warn "Failed to remount $paramsdir in RW - continuing"
cp -f /tmp/luksDump.txt "$paramsdir/kexec_lukshdr_hash.txt" ||
	warn "Failed to copy LUKS header hashes to /boot - continuing"
mount -o ro,remount $paramsdir || warn "Failed to remount $paramsdir in RO - continuing"