clevis/src/pins/tpm2/pin-tpm2

#!/bin/bash -x
# vim: set tabstop=8 shiftwidth=4 softtabstop=4 expandtab smarttab colorcolumn=80:
#
# Copyright (c) 2019 Red Hat, Inc.
# 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/>.
#

TEST=$(basename "${0}")

# Code to return to mark test as skipped.
SKIP_RET_CODE=77

tpm2_available() {
    # Old environment variables for tpm2-tools 3.0
    export TPM2TOOLS_TCTI_NAME=device
    export TPM2TOOLS_DEVICE_FILE=
    for dev in /dev/tpmrm?; do
        [ -e "${dev}" ] || continue
        TPM2TOOLS_DEVICE_FILE="${dev}"
        break
    done

    # New environment variable for tpm2-tools >= 3.1
    export TPM2TOOLS_TCTI="${TPM2TOOLS_TCTI_NAME}:${TPM2TOOLS_DEVICE_FILE}"

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

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

    local _tpm2tools_info="$(tpm2_createprimary -v)"
    local _match='version="(.)\.'
    [[ ${_tpm2tools_info} =~ ${_match} ]] && TPM2TOOLS_VERSION="${BASH_REMATCH[1]}"
    if [[ $TPM2TOOLS_VERSION -lt 3 ]] || [[ $TPM2TOOLS_VERSION -gt 5 ]]; then
        echo "The tpm2 pin requires a tpm2-tools version between 3 and 5" >&2
        return 1
    fi
    export TPM2TOOLS_VERSION
}

validate_pcrs() {
    local _pcr_bank="${1}"
    local _pcrs="${2}"
    [ -z "${_pcr_bank}" ] && return 1
    [ -z "${_pcrs}" ] && return 0

    local _fail=
    local _pcrs_r=
    case "${TPM2TOOLS_VERSION}" in
    3) _pcrs_r="$(tpm2_pcrlist -L "${_pcr_bank}":"${_pcrs}" | grep -v "^${_pcr_bank}")" || _fail=$?;;
    4|5) _pcrs_r=$(tpm2_pcrread "${_pcr_bank}":"${_pcrs}" | grep -v "  ${_pcr_bank}")  || _fail=$?;;
    *) _fail=1
    esac

    if [ -n "${_fail}" ] || [ -z "${_pcrs_r}" ]; then
        return 1
    fi
    return 0
}

# Checking if we can run this test.
if ! tpm2_available; then
    exit ${SKIP_RET_CODE}
fi

decode_jwe() {
    local jwe="${1}"

    local coded
    if ! coded=$(jose jwe fmt -i- <<< "${jwe}"); then
        return 1
    fi

    coded=$(jose fmt -j- -g protected -u- <<< "${coded}" | tr -d '"')
    jose b64 dec -i- <<< "${coded}"
}

test_pcr_ids() {
    local orig="${1}"
    local cfg="${2}"
    local expected_pcr_ids="${3}"

    local enc
    if ! enc=$(echo "${orig}" | clevis encrypt tpm2 "${cfg}"); then
        echo "${TEST}: encrypt failed for cfg: ${cfg}" >&1
        return 1
    fi

    local pcr_ids
    pcr_ids=$(decode_jwe "${enc}" \
              | jose fmt -j- -Og clevis -Og tpm2 -Og pcr_ids -u- 2>/dev/null)

    local dec
    dec=$(echo "${enc}" | clevis decrypt)

    if [ "${orig}" != "${dec}" ]; then
        echo "${TEST}: decoded text (${dec}) does not match original one (${orig})" >&2
        return 1
    fi

    if [ "${pcr_ids}" != "${expected_pcr_ids}" ]; then
        echo "${TEST}: pcr_ids (${pcr_ids}) do not match the expected (${expected_pcr_ids}) result." >&2
        return 1
    fi
}

test_enc_dec() {
    local cfg="${1}"
    output=$(echo Working | clevis encrypt tpm2 "${cfg}" | clevis decrypt)

    if [ "$output" != "Working" ]; then
        echo "Output after decrypting doesn't match: ${output} != 'Working'"
        return 1
    fi
}

test_enc_dec '{}' || exit 1
test_pcr_ids "${orig}" '{}' "" || exit 1
test_pcr_ids "${orig}" '{                   }' "" || exit 1
test_pcr_ids "${orig}" '{"key": "ecc"}' "" || exit 1

# Issue #103: now let's try a few different configs with both strings and
# arrays and check if we get the expected pcr_ids.

# Let's first make sure this would be a valid configuration.
_default_pcr_bank="sha1"
if validate_pcrs "${_default_pcr_bank}" "4,16"; then
    test_pcr_ids "${orig}" '{"pcr_ids": "16"}' "16" || exit 1
    test_pcr_ids "${orig}" '{"pcr_ids": ["16"]}' "16"  || exit 1
    test_pcr_ids "${orig}" '{"pcr_ids": "4,  16"}' "4,16" || exit 1
    test_pcr_ids "${orig}" '{"pcr_ids": "4,16"}' "4,16" || exit 1
    test_pcr_ids "${orig}" '{"pcr_ids": ["4,16"]}' "4,16" || exit 1
    test_pcr_ids "${orig}" '{"pcr_ids": [4,16]}' "4,16" || exit 1
    test_pcr_ids "${orig}" '{"pcr_ids": [4,  16]}' "4,16" || exit 1
    test_pcr_ids "${orig}" '{"pcr_ids": ["4","16"]}' "4,16" || exit 1
    ! test_pcr_ids "${orig}" '{"pcr_ids": ["4","16"]}' "foo bar" || exit 1
else
    echo "Skipping tests related to issue#103 because the combination of pcr_bank and PCRs is invalid" >&2
fi

# Test with policies if we have the PIN rewrite available
if ! $(which clevis-pin-tpm2 >/dev/null 2>&1);
then
    echo "No PIN rewrite available"
    exit 0
fi
if ! $(which clevis-pin-tpm2-signtool >/dev/null 2>&1);
then
    echo "No policy signtool available"
    exit 0
fi

function on_exit() {
    popd
    if [ ! -d "$TMP" ] || ! rm -rf "$TMP"; then
        echo "Delete temporary files failed!" >&2
        echo "You need to clean up: $TMP" >&2
        exit 1
    fi
}
if ! TMP="$(mktemp -d)"; then
    echo "Creating a temporary dir for TPM files failed!" >&2
    exit 1
fi
trap 'on_exit' EXIT
pushd $TMP

clevis-pin-tpm2-signtool >policy_working.json << EOP
---
- policy_ref:
  steps:
    - PCRs:
        hash_algorithm: sha256
        selection:
          - pcr_id: 21
            value: "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
          - pcr_id: 22
            value: "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
EOP
clevis-pin-tpm2-signtool >policy_broken.json << EOP
---
- policy_ref:
  steps:
    - PCRs:
        hash_algorithm: sha256
        selection:
          - pcr_id: 21
            value: "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFE"
          - pcr_id: 22
            value: "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
EOP

test_enc_dec '{"policy_pubkey_path":"./publickey.json", "policy_ref": "", "policy_path": "./policy_working.json"}' || exit 1
! test_enc_dec '{"policy_pubkey_path":"./publickey.json", "policy_ref": "", "policy_path": "./policy_broken.json"}' || exit 1