heads/initrd/bin/unseal-hotp
Thierry Laurion 40c34453df
all scripts: replace TRACE manual strings with dynamic tracing by bash debug
Exception: scripts sourcing/calls within etc/ash_functions continues to use old TRACE functions until we switch to bash completely getting rid of ash.
This would mean getting rid of legacy boards (flash + legacy boards which do not have enough space for bash in flash boards) once and for all.

Signed-off-by: Thierry Laurion <insurgo@riseup.net>
2024-02-01 15:48:27 -05:00

72 lines
1.9 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_FUNC
# 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_FUNC
# 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 [ "$CONFIG_TPM" = "y" ]; then
DEBUG "Unsealing HOTP secret reuses TOTP sealed secret..."
tpmr unseal 4d47 0,1,2,3,4,7 312 "$HOTP_SECRET" || die "Unable to unseal HOTP secret"
else
# without a TPM, generate a secret based on the SHA-256 of the ROM
secret_from_rom_hash > "$HOTP_SECRET" || die "Reading ROM failed"
fi
# Truncate the secret if it is longer than the maximum HOTP secret
truncate_max_bytes 20 "$HOTP_SECRET"
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