heads/initrd/bin/unseal-key
Trammell Hudson 353a0efe6f
Rework /init and qubes setup scripts (issue #27, #155, #32, #29, #110)
This adds support for seamless booting of Qubes with a TPM disk key,
as well as signing of qubes files in /boot with a Yubikey.

The signed hashes also includes a TPM counter, which is incremented
when new hashes are signed.  This prevents rollback attacks against
the /boot filesystem.

The TPMTOTP value is presented to the user at the time of entering
the disk encryption keys.  Hitting enter will generate a new code.

The LUKS headers are included in the TPM sealing of the disk
encryption keys.
2017-04-12 06:57:58 -04:00

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#!/bin/sh
# This will unseal and unecncrypt the drive encryption key from the TPM
# The TOTP secret will be shown to the user on each encryption attempt.
# It will then need to be bundled into initrd that is booted with Qubes.
TPM_INDEX=3
TPM_SIZE=312
. /etc/functions
mkdir -p /tmp/secret
sealed_file="/tmp/secret/sealed.key"
key_file="$1"
if [ -z "$key_file" ]; then
key_file="/tmp/secret/secret.key"
fi
tpm nv_readvalue \
-in "$TPM_INDEX" \
-sz "$TPM_SIZE" \
-of "$sealed_file" \
|| die "Unable to read key from TPM NVRAM"
for tries in 1 2 3; do
tpm_password=
while [ -z "$tpm_password" ]; do
unseal-totp || die "TOTP code generation failed"
read -s -p "Disk unlock password: " tpm_password
echo
done
if tpm unsealfile \
-if "$sealed_file" \
-of "$key_file" \
-pwdd "$tpm_password" \
-hk 40000000 \
; then
rm -f /tmp/secret/sealed
exit 0
fi
pcrs
warn "Unable to unseal disk encryption key"
done
die "Retry count exceeded..."