heads/initrd/bin/kexec-seal-key

#!/bin/bash
# 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.
set -e -o pipefail
. /etc/functions

TPM_INDEX=3
TPM_SIZE=312
KEY_FILE="/tmp/secret/secret.key"
TPM_SEALED="/tmp/secret/secret.sealed"
RECOVERY_KEY="/tmp/secret/recovery.key"

. /etc/functions
. /tmp/config

TRACE "Under kexec-seal-key"

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"

if [ ! -r "$KEY_DEVICES" ]; then
	die "No devices defined for disk encryption"
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"
fi

DEBUG "$(pcrs)"

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

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

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

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

# Remove all the old keys from slot 1
for dev in `cat "$KEY_DEVICES" | cut -d\  -f1`; do
	echo "++++++ $dev: Removing old key slot"
	cryptsetup luksKillSlot \
		--key-file "$RECOVERY_KEY" \
		$dev 1 \
	|| warn "$dev: ignoring problem"

	echo "++++++ $dev: Adding key"
	cryptsetup luksAddKey \
		--key-file "$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
# 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
cat "$KEY_DEVICES" | cut -d\  -f1 | xargs /bin/qubes-measure-luks \
	|| die "Unable to measure the LUKS headers"

if [ "$CONFIG_TPM" = "y" ] && [ "$CONFIG_TPM2_TOOLS" != "y" ]; then
	luks_pcr=`tpm calcfuturepcr -ix 16 -if /tmp/luksDump.txt`
	# HOTP USB Secrity Dongle loads USB modules which changes PCR5.
	# In the event HOTP USB Security Dongle is enabled, skip verification of PCR5
	# If modules should be loaded during normal boot, skip verification of PCR5
	#
	#TODO: check condition, no libdata.ko
	if [ "$CONFIG_USB_KEYBOARD" = "y" -o -r /lib/modules/libata.ko -o -x /bin/hotp_verification ]; then
		pcr_5="X"
	else
		pcr_5="0000000000000000000000000000000000000000"
	fi

	# 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 "init" mode
	# used to be -ix 4 f8fa3b6e32e7c6fe04c366e74636e505b28f3b0d \
	# now just all zeros in a normal boot
	# 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 "$KEY_FILE" \
		-of "$TPM_SEALED" \
		-pwdd "$key_password" \
		-hk 40000000 \
		-ix 0 X \
		-ix 1 X \
		-ix 2 X \
		-ix 3 X \
		-ix 4 0000000000000000000000000000000000000000 \
		-ix 5 $pcr_5 \
		-ix 6 $luks_pcr \
		-ix 7 X

	if [ $? -ne 0 ]; then
		die "Unable to seal secret"
	fi

	shred -n 10 -z -u "$KEY_FILE" 2> /dev/null \
		|| die "Failed to delete key file"

	# try it without the owner password first
	if ! tpm nv_writevalue \
		-in $TPM_INDEX \
		-if "$TPM_SEALED" \
		; then
		# 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 $TPM_INDEX \
			-if "$TPM_SEALED" \
			|| die "Unable to write sealed secret to NVRAM"
	fi
elif [ "$CONFIG_TPM2_TOOLS" = "y" ]; then
	pcrf="/tmp/secret/pcrf.bin"
	#TODO: verify logic below against tpm2
	tpm2 pcrread -o "$pcrf" sha256:0,1,2,3
	# pcr 4 is expected to be zero (init mode)
	dd if=/dev/zero bs=32 count=1 >> "$pcrf"
	if [ "$CONFIG_USB_KEYBOARD" = "y" -o -r /lib/modules/libata.ko -o -x /bin/hotp_verification ]; then
		DEBUG "TPM2, 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
		# 
		# binary pcr dump can only go via stderr for redirection
		# sadly this busybox has buggy support for "2>>" and "2|"
		# so we need workaround...
		DEBUG "tpm2 pcrread -o /dev/stderr sha256:5 2>&1 >/dev/console | cat >> "$pcrf""
		tpm2 pcrread -o /dev/stderr sha256:5 2>&1 >/dev/console | cat >> "$pcrf"
	else
		DEBUG "TPM2, without PCR5 involvement. Inserting 32 zero bytes under pcrf..."
		#no kernel modules are expected to be measured+loaded
		dd if=/dev/zero bs=32 count=1 >> "$pcrf"
	fi
	# Use pcr 23 to precompute the value for pcr 6
	tpm2 pcrreset 23
	tpmr extend -ix 23 -if /tmp/luksDump.txt
	tpm2 pcrread -o /dev/stderr sha256:23 2>&1 >/dev/console | cat >> "$pcrf"
	# goal is to validate that what is in pcr 23 is at pcr 6 at unseal
	DEBUG "PCR23 content used to simulate PCR6 content at unseal:" 
	DEBUG "$(pcrs)"
	tpm2 pcrreset 23
	# We take into consideration user files in cbfs
	DEBUG "tpm2 pcrread -o /dev/stderr sha256:7 2>&1 >/dev/console | cat >> "$pcrf""
	tpm2 pcrread -o /dev/stderr sha256:7 2>&1 >/dev/console | cat >> "$pcrf"
	DEBUG "tpmr seal $KEY_FILE 0x8100000$TPM_INDEX sha256:0,1,2,3,4,5,6,7 $pcrf <password>"
	tpmr seal "$KEY_FILE" "0x8100000$TPM_INDEX" sha256:0,1,2,3,4,5,6,7 "$pcrf" "$key_password"
	if [ $? -eq 0 ]; then
		# should be okay if this fails
		shred -n 10 -z -u "$pcrf".* 2> /dev/null || true
	fi
fi

shred -n 10 -z -u "$TPM_SEALED" 2> /dev/null \
|| warn "Failed to delete the sealed secret - continuing"

cp /tmp/luksDump.txt "$paramsdir/kexec_lukshdr_hash.txt" \
|| warn "Failed to have hashes of LUKS header - continuing"