heads/initrd/bin/unseal-hotp
Jonathon Hall 7b8824adf1
seal-totp, kexec-seal-key: Use common logic for TPM1 and TPM2
Provide tpmr commands pcrread, pcrsize, calcfuturepcr, and seal for
both TPM1 and TPM2.

Combine seal logic for TPM1/TPM2 in seal-totp, kexec-seal-key.  This is
essentially the TPM2 logic now that tpmr provides the same wrapped
commands for both TPM1 and TPM2.

Remove algorithm prefix from PCR list in tpmr unseal for consistency
with tpmr seal.

Signed-off-by: Jonathon Hall <jonathon.hall@puri.sm>
2023-03-08 12:45:57 -05:00

65 lines
1.6 KiB
Bash
Executable File

#!/bin/bash
# Retrieve the sealed file and counter from the NVRAM, unseal it and compute the hotp
. /etc/functions
HOTP_SECRET="/tmp/secret/hotp.key"
HOTP_COUNTER="/boot/kexec_hotp_counter"
mount_boot_or_die()
{
TRACE "Under /bin/unseal-hotp:mount_boot_or_die"
# Mount local disk if it is not already mounted
if ! grep -q /boot /proc/mounts ; then
mount -o ro /boot \
|| die "Unable to mount /boot"
fi
}
TRACE "Under /bin/unseal-hotp"
# Store counter in file instead of TPM for now, as it conflicts with Heads
# config TPM counter as TPM 1.2 can only increment one counter between reboots
# get current value of HOTP counter in TPM, create if absent
mount_boot_or_die
#check_tpm_counter $HOTP_COUNTER hotp \
#|| die "Unable to find/create TPM counter"
#counter="$TPM_COUNTER"
#
#counter_value=$(read_tpm_counter $counter | cut -f2 -d ' ' | awk 'gsub("^000e","")')
#
counter_value=$(cat $HOTP_COUNTER)
if [ "$counter_value" == "" ]; then
die "Unable to read HOTP counter"
fi
#counter_value=$(printf "%d" 0x${counter_value})
if [ "$CONFIG_TPM" = "y" ]; then
tpmr unseal 4d47 0,1,2,3,4,7 312 "$HOTP_SECRET"
fi
if ! hotp $counter_value < "$HOTP_SECRET"; then
shred -n 10 -z -u "$HOTP_SECRET" 2> /dev/null
die 'Unable to compute HOTP hash?'
fi
shred -n 10 -z -u "$HOTP_SECRET" 2> /dev/null
#increment_tpm_counter $counter > /dev/null \
#|| die "Unable to increment tpm counter"
mount -o remount,rw /boot
counter_value=`expr $counter_value + 1`
echo $counter_value > $HOTP_COUNTER \
|| die "Unable to create hotp counter file"
#sha256sum /tmp/counter-$counter > $HOTP_COUNTER \
#|| die "Unable to create hotp counter file"
mount -o remount,ro /boot
exit 0