heads/initrd/bin/unseal-hotp
Thierry Laurion 8259d3ca1e
Add TRACE function tracing function to output on console when enabled
- Add TRACE function tracing output under etc/functions, depending on CONFIG_ENABLE_FUNCTION_TRACING_OUTPUT enabled in board configs
- Replace current DEBUG to TRACE calls in code, reserving DEBUG calls for more verbose debugging later on (output of variables etc)
- add 'export CONFIG_ENABLE_FUNCTION_TRACING_OUTPUT=y' in qemu-coreboot(fb)whiptail-tpm1(-hotp) boards to see it in action
2023-02-20 11:44:52 -05:00

77 lines
1.9 KiB
Bash
Executable File

#!/bin/sh
# Retrieve the sealed file and counter from the NVRAM, unseal it and compute the hotp
. /etc/functions
HOTP_SEALED="/tmp/secret/hotp.sealed"
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})
tpm nv_readvalue \
-in 4d47 \
-sz 312 \
-of "$HOTP_SEALED" \
|| die "Unable to retrieve sealed file from TPM NV"
tpm unsealfile \
-hk 40000000 \
-if "$HOTP_SEALED" \
-of "$HOTP_SECRET" \
|| die "Unable to unseal HOTP secret"
shred -n 10 -z -u "$HOTP_SEALED" 2> /dev/null
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