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60 lines
1.4 KiB
Bash
Executable File
60 lines
1.4 KiB
Bash
Executable File
#!/usr/bin/env bash
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# Copyright (c) Edgeless Systems GmbH
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#
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# SPDX-License-Identifier: AGPL-3.0-only
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# This script is used to precalculate the PCR[9] value for a Constellation OS image.
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# PCR[9] contains the hash of the initrd and is measured by the linux kernel after loading the initrd.
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# Usage: precalculate_pcr_9.sh <path to image> <path to output file>
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set -euo pipefail
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shopt -s inherit_errexit
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source "$(dirname "$0")/measure_util.sh"
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get_initrd_from_uki() {
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local uki="$1"
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local output="$2"
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objcopy -O binary --only-section=.initrd "${uki}" "${output}"
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}
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initrd_measure() {
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local path="$1"
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sha256sum "${path}" | cut -d " " -f 1
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}
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write_output() {
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local out="$1"
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cat > "${out}" << EOF
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{
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"measurements": {
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"9": {
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"expected": "${expected_pcr_9}"
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}
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},
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"initrd-sha256": "${initrd_hash}"
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}
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EOF
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}
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DIR=$(mktempdir)
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trap 'cleanup "${DIR}"' EXIT
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extract "$1" "/efi/EFI/Linux" "${DIR}/uki"
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sudo chown -R "${USER}:${USER}" "${DIR}/uki"
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cp "${DIR}"/uki/*.efi "${DIR}/03-uki.efi"
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get_initrd_from_uki "${DIR}/03-uki.efi" "${DIR}/initrd"
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initrd_hash=$(initrd_measure "${DIR}/initrd")
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cleanup "${DIR}"
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expected_pcr_9=0000000000000000000000000000000000000000000000000000000000000000
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expected_pcr_9=$(pcr_extend "${expected_pcr_9}" "${initrd_hash}" "sha256sum")
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echo "Initrd measurement ${initrd_hash}"
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echo ""
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echo "Expected PCR[9]: ${expected_pcr_9}"
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echo ""
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write_output "$2"
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