heads/initrd/bin/seal-hotpkey
Jonathon Hall e6acaad215
tpmr: Fix sealing/unsealing file with both PCRs and passwords
When sealing/unsealing with a password, use a policy including both the
specified PCRs and the object password.  Fixes sealing and unsealing
disk unlock key.

tpm2 seems to have a bug in parameter decryption when using a policy
session and password in this way, disable encryption in the policy
session as a workaround.

Flags still need to be set on the sealed object correctly, as the
password is normally allowed on its own as an alternative to policy
auth.

Add -Q to some tpm2 invocations to silence diagnostics on stdout.

Pass filename for unsealed secret rather than capturing from stdout
for robustness against tpm2 diagnostics on stdout.

Fix unseal result check in kexec-unseal-key.

Signed-off-by: Jonathon Hall <jonathon.hall@puri.sm>
2023-03-08 12:45:48 -05:00

131 lines
3.6 KiB
Bash
Executable File

#!/bin/bash
# Retrieve the sealed TOTP secret and initialize a USB Security dongle with it
. /etc/functions
HOTP_SEALED="/tmp/secret/hotp.sealed"
HOTP_SECRET="/tmp/secret/hotp.key"
HOTP_COUNTER="/boot/kexec_hotp_counter"
HOTP_KEY="/boot/kexec_hotp_key"
mount_boot()
{
TRACE "Under /bin/seal-htopkey:mount_boot"
# Mount local disk if it is not already mounted
if ! grep -q /boot /proc/mounts ; then
mount -o ro /boot \
|| recovery "Unable to mount /boot"
fi
}
TRACE "Under /bin/seal-hotpkey"
# Use stored HOTP key branding (this might be useful after OEM reset)
if [ -r /boot/kexec_hotp_key ]; then
HOTPKEY_BRANDING="$(cat /boot/kexec_hotp_key)"
else
HOTPKEY_BRANDING="HOTP USB Security Dongle"
fi
if [ "$CONFIG_TPM" = "y" ] && [ "$CONFIG_TPM2_TOOLS" != "y" ]; then
tpm nv_readvalue \
-in 4d47 \
-sz 312 \
-of "$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"
elif [ "$CONFIG_TPM2_TOOLS" = "y" ]; then
tpmr unseal 0x81004d47 sha256:0,1,2,3,4,7 "$HOTP_SECRET" \
|| die "Unable to unseal HOTP secret"
fi
shred -n 10 -z -u "$HOTP_SEALED" 2> /dev/null
# 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
#check_tpm_counter $HOTP_COUNTER hotp \
#|| die "Unable to find/create TPM counter"
#counter="$TPM_COUNTER"
#
#counter_value=$(read_tpm_counter $counter | cut -f2 -d ' ' | awk 'gsub("^000e","")')
#if [ "$counter_value" == "" ]; then
# die "Unable to read HOTP counter"
#fi
#counter_value=$(printf "%d" 0x${counter_value})
counter_value=1
enable_usb
if ! hotp_verification info ; then
echo "Insert your $HOTPKEY_BRANDING and press Enter to configure it"
read
if ! hotp_verification info ; then
# don't leak key on failure
shred -n 10 -z -u "$HOTP_SECRET" 2> /dev/null
die "Unable to find $HOTPKEY_BRANDING"
fi
fi
# Set HOTP USB Security Dongle branding based on VID
if lsusb | grep -q "20a0:" ; then
HOTPKEY_BRANDING="Nitrokey"
elif lsusb | grep -q "316d:" ; then
HOTPKEY_BRANDING="Librem Key"
else
HOTPKEY_BRANDING="HOTP USB Security Dongle"
fi
echo -e ""
read -s -p "Enter your $HOTPKEY_BRANDING Admin PIN: " admin_pin
echo -e "\n"
hotp_initialize "$admin_pin" $HOTP_SECRET $counter_value "$HOTPKEY_BRANDING"
if [ $? -ne 0 ]; then
echo -e "\n"
read -s -p "Error setting HOTP secret, re-enter Admin PIN and try again: " admin_pin
echo -e "\n"
if ! hotp_initialize "$admin_pin" $HOTP_SECRET $counter_value "$HOTPKEY_BRANDING" ; then
# don't leak key on failure
shred -n 10 -z -u "$HOTP_SECRET" 2> /dev/null
die "Setting HOTP secret failed"
fi
fi
# HOTP key no longer needed
shred -n 10 -z -u "$HOTP_SECRET" 2> /dev/null
# Make sure our counter is incremented ahead of the next check
#increment_tpm_counter $counter > /dev/null \
#|| die "Unable to increment tpm counter"
#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"
# Store/overwrite HOTP USB Security Dongle branding found out beforehand
echo $HOTPKEY_BRANDING > $HOTP_KEY \
|| die "Unable to store hotp key file"
#sha256sum /tmp/counter-$counter > $HOTP_COUNTER \
#|| die "Unable to create hotp counter file"
mount -o remount,ro /boot
echo -e "\n$HOTPKEY_BRANDING initialized successfully. Press Enter to continue."
read
exit 0