clevis/src/clevis-encrypt-tpm2

#!/bin/bash -e
# vim: set tabstop=8 shiftwidth=4 softtabstop=4 expandtab smarttab colorcolumn=80:
#
# Copyright (c) 2017 Red Hat, Inc.
# Author: Javier Martinez Canillas <javierm@redhat.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

SUMMARY="Encrypts using a TPM2.0 chip binding policy"
# The owner hierarchy is the one that should be used by the Operating System.
auth="o"
# Algorithm type must be keyedhash for object with user provided sensitive data.
alg_create_key="keyedhash"
# Attributes for the created TPM2 object with the JWK as sensitive data.
obj_attr="fixedtpm|fixedparent|sensitivedataorigin|noda|adminwithpolicy"

function on_exit() {
    if ! rm -rf $TMP; then
        echo "Delete temporary files failed!" >&2
        exit 1
    fi
}

if [ "$1" == "--summary" ]; then
    echo "$SUMMARY"
    exit 0
fi

if [ -t 0 ]; then
    echo >&2
    echo "Usage: clevis encrypt tpm2 CONFIG < PLAINTEXT > JWE" >&2
    echo >&2
    echo $SUMMARY >&2
    echo >&2
    echo "This command uses the following configuration properties:" >&2
    echo >&2
    echo "  hash: <string>  Hash algorithm used in the computation of the object name (default: sha256)" >&2
    echo >&2
    echo "  key: <string>   Algorithm type for the generated key (default: ecc)" >&2
    echo >&2
    echo "  pcr_bank: <string>   PCR algorithm bank to use for policy (default: sha1)" >&2
    echo >&2
    echo "  pcr_ids: <string>   PCR list used for policy. If not present, no policy is used" >&2
    echo >&2
    echo "  pcr_digest: <string>   Binary PCR hashes encoded in base64. If not present, the hash values are looked up" >&2
    echo >&2
    exit 1
fi

export TPM2TOOLS_TCTI_NAME=device
export TPM2TOOLS_DEVICE_FILE=`ls /dev/tpmrm? 2>/dev/null`

if [ -z "${TPM2TOOLS_DEVICE_FILE[0]}" ]; then
    echo "A TPM2 device with the in-kernel resource manager is needed!" >&2
    exit 1
fi

if ! [[ -r "${TPM2TOOLS_DEVICE_FILE[0]}" && -w "${TPM2TOOLS_DEVICE_FILE[0]}" ]]; then
    echo "The ${TPM2TOOLS_DEVICE_FILE[0]} device must be readable and writable!" >&2
    exit 1
fi

if ! cfg=`jose fmt -j "$1" -Oo- 2>/dev/null`; then
    echo "Configuration is malformed!" >&2
    exit 1
fi

hash=`jose fmt -j- -Og hash -u- <<< "$cfg"` || hash="sha256"

key=`jose fmt -j- -Og key -u- <<< "$cfg"` || key="ecc"

pcr_bank=`jose fmt -j- -Og pcr_hash -u- <<< "$cfg"` || pcr_bank="sha1"

pcr_ids=`jose fmt -j- -Og pcr_ids -u- <<< "$cfg"` || true

pcr_digest=`jose fmt -j- -Og pcr_digest -u- <<< "$cfg"` || true

if ! jwk=`jose jwk gen -i '{"alg":"A256GCM"}'`; then
    echo "Generating a jwk failed!" >&2
    exit 1
fi

if ! TMP=`mktemp -d`; then
    echo "Creating a temporary dir for TPM files failed!" >&2
    exit 1
fi

trap 'on_exit' EXIT

if ! tpm2_createprimary -Q -H "$auth" -g "$hash" -G "$key" -C $TMP/primary.context; then
    echo "Creating TPM2 primary key failed!" >&2
    exit 1
fi

if [ -n "$pcr_ids" ]; then
    if [ -z "$pcr_digest" ]; then
        if ! tpm2_pcrlist -Q -L "$pcr_bank":"$pcr_ids" -o $TMP/pcr.digest; then
            echo "Creating PCR hashes file failed!" >&2
            exit 1
        fi
    else
        if ! jose b64 dec -i- -O "$TMP"/pcr.digest <<< "$pcr_digest"; then
            echo "Error decoding PCR digest!" >&2
            exit 1
        fi
    fi

    if ! tpm2_createpolicy -Q -P -L "$pcr_bank":"$pcr_ids" -F $TMP/pcr.digest -f $TMP/pcr.policy; then
        echo "create policy fail, please check the environment or parameters!"
        exit 1
    fi

    policy_options="-L $TMP/pcr.policy"
fi

if ! tpm2_create -Q -g "$hash" -G "$alg_create_key" -c $TMP/primary.context -u $TMP/jwk.pub \
     -r $TMP/jwk.priv -A "$obj_attr" $policy_options -I- <<< "$jwk"; then
    echo "Creating TPM2 object for jwk failed!" >&2
    exit 1
fi

if ! jwk_pub=`jose b64 enc -I $TMP/jwk.pub`; then
    echo "Encoding jwk.pub in Base64 failed!" >&2
    exit 1
fi

if ! jwk_priv=`jose b64 enc -I $TMP/jwk.priv`; then
    echo "Encoding jwk.priv in Base64 failed!" >&2
    exit 1
fi

jwe='{"protected":{"clevis":{"pin":"tpm2","tpm2":{}}}}'
jwe=`jose fmt -j "$jwe" -g protected -g clevis -g tpm2 -q "$hash" -s hash -UUUUo-`
jwe=`jose fmt -j "$jwe" -g protected -g clevis -g tpm2 -q "$key" -s key -UUUUo-`

if [ -n "$pcr_ids" ]; then
    jwe=`jose fmt -j "$jwe" -g protected -g clevis -g tpm2 -q "$pcr_bank" -s pcr_bank -UUUUo-`
    jwe=`jose fmt -j "$jwe" -g protected -g clevis -g tpm2 -q "$pcr_ids" -s pcr_ids -UUUUo-`
fi

jwe=`jose fmt -j "$jwe" -g protected -g clevis -g tpm2 -q "$jwk_pub" -s jwk_pub -UUUUo-`
jwe=`jose fmt -j "$jwe" -g protected -g clevis -g tpm2 -q "$jwk_priv" -s jwk_priv -UUUUo-`

jose jwe enc -i- -k- -I- -c < <(echo -n "$jwe$jwk"; cat)