#!/bin/bash -e
# vim: set ts=8 shiftwidth=4 softtabstop=4 expandtab smarttab colorcolumn=80:
#
# Copyright (c) 2018, 2020 Red Hat, Inc.
# Author: Radovan Sroka <rsroka@redhat.com>
# Author: Sergio Correia <scorreia@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/>.
#

. clevis-luks-common-functions

SUMMARY="Report tang keys' rotations"

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

report_compare() {
    local adv_keys="${1}"
    local mdata_keys="${2}"
    [ -z "${adv_keys}" ] && return 1
    [ -z "${mdata_keys}" ] && return 1

    local thp keys
    for thp in $(printf '%s' "${mdata_keys}" | jose jwk thp --input=-); do
        if ! printf '%s' "${adv_keys}" | jose jwk thp --input=- \
                                              --find "${thp}" >/dev/null; then
            keys="$(printf '%s %s' "${keys}" "${thp}")"
        fi
    done
    printf '%s' "${keys}"
}

report_tang() {
    local content="${1}"
    [ -z "${content}" ] && return 1

    local url
    if ! url="$(jose fmt --json="${content}" --get url --unquote=-)" \
                || [ -z "${url}" ]; then
        echo "Invalid tang metadata; URL not found" >&2
        return 1
    fi

    local jws
    if ! jws="$(curl -sfg "${url}/adv")"; then
        echo "Unable to fetch advertisement (${url}/adv)" >&2
        return 1
    fi

    local adv_keys
    if ! adv_keys="$(jose fmt --json="${jws}" --object --get payload \
                     --string --b64load --object --get keys \
                     --array --unwind --output=-)"; then
        echo "Advertisement is malformed" >&2
        return 1
    fi

    # Check advertisement validity.
    local ver
    if ! ver="$(printf '%s' "${adv_keys}" | jose jwk use --input=- \
                                                 --required \
                                                 --use=verify \
                                                 --output=-)"; then
        echo "Unable to validate advertisement" >&2
        return 1
    fi
    if ! printf '%s' "${ver}" | jose jws ver --input="${jws}" --key=- \
                                     --all; then
        echo "Advertisement is missing signatures" >&2
        return 1
    fi
    local mdata_keys
    if ! mdata_keys="$(jose fmt --json="${content}" --get adv --output=-)" \
                       || [ -z "${mdata_keys}" ]; then
        echo "Keys from clevis metadata not found" >&2
        return 1
    fi
    report_compare "${adv_keys}" "${mdata_keys}"
}

report_sss() {
    local content="${1}"
    [ -z "${content}" ] && return 1

    local jwe
    for jwe in $(jose fmt --json="${content}" --get jwe --foreach=-); do
        jwe="$(printf '%s' "${jwe}" | sed -e 's/"//g')"
        report_decode "${jwe}"
    done
}

report_decode() {
    local data64="${1}"
    [ -z "${data64}" ] && return 1

    local data
    if ! data="$(clevis_luks_decode_jwe "${data64}")" || [ -z "${data}" ]; then
        echo "Unable to decode metadata" >&2
        exit 1
    fi

    local pin
    if ! pin="$(jose fmt --json="${data}" --get clevis --get pin --unquote=-)" \
                || [ -z "${pin}" ]; then
        echo "Pin not found in clevis metadata" >&2
        exit 1
    fi

    local content
    if ! content="$(jose fmt --json="${data}" --get clevis --get "${pin}" \
                    --output=-)" || [ -z "${content}" ]; then
        echo "Invalid pin metadata; no content found" >&2
        return 1
    fi

    case "${pin}" in
    tang)
        report_tang "${content}"
        ;;
    sss)
        report_sss "${content}"
        ;;
    esac
}

usage_and_exit () {
    exec >&2
    echo "Usage: clevis luks report [-q] [-r] -d DEV -s SLOT"
    echo
    echo "${SUMMARY}"
    echo
    echo "  -d DEV  The LUKS device to check for key rotations"
    echo
    echo "  -s SLT  The LUKS slot to use"
    echo
    echo "  -q      Quiet mode; do not prompt for using 'clevis luks regen'"
    echo
    echo "  -r      Regenerate binding with 'clevis luks regen -q -d DEV -s SLOT'"
    echo
    exit "${1}"
}

while getopts "hd:s:rq" o; do
    case "${o}" in
    d) DEV="${OPTARG}";;
    h) usage_and_exit 0;;
    r) ROPT="regen";;
    s) SLT="${OPTARG}";;
    q) QOPT="quiet";;
    *) usage_and_exit 1;;
    esac
done

if [ -z "${DEV}" ]; then
    echo "Did not specify a device!" >&2
    exit 1
fi

if [ -z "${SLT}" ]; then
    echo "Did not specify a slot!" >&2
    exit 1
fi

if ! data64="$(clevis_luks_read_slot "${DEV}" "${SLT}")" \
               || [ -z "${data64}" ]; then
    # Error message was already displayed by clevis_luks_read_slot(),
    # at this point.
    exit 1
fi

if ! keys="$(report_decode "${data64}")"; then
    echo "Unable to verify whether there are rotated keys" >&2
    exit 1
fi

# No rotated keys.
[ -z "${keys}" ] && exit 0

echo "The following keys are not in the current advertisement and were probably rotated:"
for k in ${keys}; do
    printf '  %s\n' "${k}"
done


if [ -z "${QOPT}" ] && [ -z "${ROPT}" ]; then
    read -r -p "Do you want to regenerate the binding with \"clevis luks regen -q -d ${DEV} -s ${SLT}\"? [ynYN] " ans
    if [ "${ans}" = "y" ] || [ "${ans}" = "Y" ]; then
        ROPT="regen"
    fi
fi

if [ "${ROPT}" = "regen" ]; then
    if ! EXE="$(command -v clevis-luks-regen)" || [ -z "${EXE}" ]; then
        echo "Unable to find clevis luks regen" >&2
        exit 1
    fi
    exec "${EXE}" -q -d "${DEV}" -s "${SLT}"
fi
exit 1