msw
ab827e9c05
🛡️ Shell Script Linting / 🛡️ Shell Script Linting (push) Has been cancelled
Signed-off-by: Marc S. Weidner <msw@coresecret.dev>
254 lines
8.1 KiB
Bash
254 lines
8.1 KiB
Bash
#!/bin/bash
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# shellcheck disable=SC2154
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# SPDX-Version: 3.0
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# SPDX-CreationInfo: 2025-10-11; WEIDNER, Marc S.; <msw@coresecret.dev>
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# SPDX-ExternalRef: GIT https://git.coresecret.dev/msw/CISS.debian.live.builder.git
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# SPDX-FileContributor: WEIDNER, Marc S.; Centurion Intelligence Consulting Agency
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# SPDX-FileCopyrightText: 2024-2025; WEIDNER, Marc S.; <msw@coresecret.dev>
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# SPDX-FileType: SOURCE
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# SPDX-License-Identifier: LicenseRef-CNCL-1.1 OR LicenseRef-CCLA-1.1
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# SPDX-LicenseComment: This file is part of the CISS.debian.installer.secure framework.
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# SPDX-PackageName: CISS.debian.live.builder
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# SPDX-Security-Contact: security@coresecret.eu
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set -Ceuo pipefail
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# Final live-build binary hook for encrypted root filesystem packaging. It creates and signs a deterministic attestation
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# manifest for the final filesystem.squashfs byte stream, preallocates a LUKS2 container, formats it with the generated build
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# secret, copies the generated filesystem.squashfs into the opened encrypted mapping, then closes the container, shreds the
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# temporary LUKS secret, and removes the plaintext SquashFS from the ISO payload.
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printf "\e[95m🧪 '%s' starting ... \e[0m\n" "${0}"
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__umask=$(umask)
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umask 0077
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#######################################
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# Pre allocates space for LUKS container.
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# Globals:
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# None
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# Arguments:
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# 1: LUKS Container
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# 2: LUKS Container Size
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# Returns:
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# 0: on success
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# 42: on failure
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#######################################
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preallocate() {
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declare file="$1" size="$2"
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declare -i blocksize=$((8*1024*1024))
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declare -i blockcounter=$(( (size + blocksize - 1) / blocksize ))
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if fallocate -l "${size}" -- "${file}" 2>/dev/null; then
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printf "\e[92m✅ [fallocate -l %s -- %s] successful. \e[0m\n" "${size}" "${file}"
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return 0
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else
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printf "\e[91m❌ [fallocate -l %s -- %s] NOT successful. \e[0m\n" "${size}" "${file}"
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fi
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if dd if=/dev/zero of="${file}" bs="${blocksize}" count="${blockcounter}" status=progress conv=fsync; then
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printf "\e[92m✅ [dd if=/dev/zero of=%s bs=%s count=%s status=progress conv=fsync] successful. \e[0m\n" "${file}" "${blocksize}" "${blockcounter}"
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return 0
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else
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printf "\e[91m❌ [dd if=/dev/zero of=%s bs=%s count=%s status=progress conv=fsync] NOT successful. \e[0m\n" "${file}" "${blocksize}" "${blockcounter}"
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return 42
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fi
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}
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### Prevents accidental 'unset -f'.
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# shellcheck disable=SC2034
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readonly -f preallocate
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#######################################
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# Create and sign the rootfs attestation manifest for the exact SquashFS payload copied into the LUKS mapper.
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# Globals:
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# VAR_SIGNING_KEY_FPR
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# VAR_SIGNING_KEY_PASSFILE
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# VAR_VERIFY_KEYRING
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# Arguments:
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# 1: Final SquashFS payload file
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# 2: Manifest path below binary/live
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# Returns:
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# 0: on success
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# 42: on failure
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#######################################
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create_attestation() {
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declare rootfs_file="$1"
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declare rootfs_attestation="$2"
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declare rootfs_hash=""
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declare rootfs_size=""
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rootfs_size="$(stat -c%s -- "${rootfs_file}")"
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rootfs_hash="$(LC_ALL=C sha512sum "${rootfs_file}")"
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rootfs_hash="${rootfs_hash%% *}"
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if printf '%s %s\n' "${rootfs_hash}" "${rootfs_file}" | LC_ALL=C sha512sum -c --strict --quiet; then
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printf "\e[92m✅ [LC_ALL=C sha512sum -c --strict --quiet of %s] successful. \e[0m\n" "${rootfs_file}"
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else
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printf "\e[91m❌ [LC_ALL=C sha512sum -c --strict --quiet of %s] NOT successful. \e[0m\n" "${rootfs_file}"
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return 42
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fi
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# The attested boundary is the final SquashFS byte stream before LUKS wrapping. The boot verifier reads exactly this many
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# bytes from the decrypted mapper and intentionally excludes the LUKS allocation slack after the SquashFS payload.
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cat << EOF >| "${rootfs_attestation}"
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# CISS.debian.live.builder Master ${VAR_VERSION}
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# Attestation file for filesystem.squashfs Version 1.0.0
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# Boundary : Final filesystem.squashfs byte stream copied into /dev/mapper/crypt_liveiso
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# Bytes : Final filesystem.squashfs ${VAR_ROOTFS_SIZE}
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${rootfs_hash} ciss-rootfs.squashfs
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EOF
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chmod 0444 "${rootfs_attestation}"
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if gpg --batch --yes --pinentry-mode loopback --passphrase-file "${VAR_SIGNING_KEY_PASSFILE}" --local-user "${VAR_SIGNING_KEY_FPR}" \
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--detach-sign --output "${rootfs_attestation}.sig" "${rootfs_attestation}"; then
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printf "\e[92m✅ [gpg of %s] successful. \e[0m\n" "${rootfs_attestation}"
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else
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printf "\e[91m❌ [gpg of %s] NOT successful. \e[0m\n" "${rootfs_attestation}"
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return 42
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fi
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chmod 0444 "${rootfs_attestation}.sig"
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if gpgv --keyring "${VAR_VERIFY_KEYRING}" "${rootfs_attestation}.sig" "${rootfs_attestation}"; then
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printf "\e[92m✅ [gpgv of %s] successful. \e[0m\n" "${rootfs_attestation}.sig"
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else
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printf "\e[91m❌ [gpgv of %s] NOT successful. \e[0m\n" "${rootfs_attestation}.sig"
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return 42
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fi
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printf "\e[92m[INFO] Rootfs attestation manifest created and verified: [%s]. \e[0m\n" "${rootfs_attestation}"
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return 0
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}
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### Prevents accidental 'unset -f'.
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# shellcheck disable=SC2034
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readonly -f create_attestation
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declare LUKSFS="${VAR_HANDLER_BUILD_DIR}/binary/live/ciss_rootfs.crypt"
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declare ROOTFS="${VAR_HANDLER_BUILD_DIR}/binary/live/filesystem.squashfs"
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declare ROOTFS_ATTESTATION="${VAR_HANDLER_BUILD_DIR}/binary/live/filesystem.squashfs.sha512sum.txt"
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declare DM_LAB="crypt_liveiso"
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declare DEVMAP="/dev/mapper/${DM_LAB}"
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declare LUKS_KEY_FILE="${VAR_TMP_SECRET}/${VAR_LUKS_KEY:-luks.txt}"
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declare KEYFD=""
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# shellcheck disable=SC2155
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declare -i VAR_ROOTFS_SIZE="$(stat -c%s -- "${ROOTFS}")"
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### Attestation Boundary
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# - The attested boundary is the final SquashFS byte stream before LUKS wrapping.
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# - The boot verifier reads exactly this many bytes from the decrypted mapper and intentionally excludes the LUKS allocation
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# slack after the SquashFS payload.
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printf "\e[95m🧪 Attestation of filesystem.squashfs ... \e[0m\n"
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create_attestation "${ROOTFS}" "${ROOTFS_ATTESTATION}"
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printf "\e[92m✅ Attestation of filesystem.squashfs successful. \e[0m\n"
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### Safety margin:
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# - LUKS2-Header and Metadata
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# - dm-integrity Overhead (Tags and Journal)
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# - Filesystem-Slack
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declare -i OVERHEAD_FIXED=$((64 * 1024 * 1024))
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declare -i OVERHEAD_PCT=2
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declare -i ALIGN_BYTES=$(( 4096 * 1024 ))
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declare -i BASE_SIZE=$(( VAR_ROOTFS_SIZE + OVERHEAD_FIXED + (VAR_ROOTFS_SIZE * OVERHEAD_PCT / 100) ))
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declare -i VAR_LUKSFS_SIZE=$(( ( (BASE_SIZE + ALIGN_BYTES - 1) / ALIGN_BYTES ) * ALIGN_BYTES ))
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preallocate "${LUKSFS}" "${VAR_LUKSFS_SIZE}"
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exec {KEYFD}<"${LUKS_KEY_FILE}"
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if [[ "${VAR_CDLB_INSIDE_RUNNER}" == "false" ]]; then
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cryptsetup luksFormat \
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--batch-mode \
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--cipher aes-xts-plain64 \
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--integrity hmac-sha512 \
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--iter-time 1000 \
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--key-file "/proc/$$/fd/${KEYFD}" \
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--key-size 512 \
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--label "${DM_LAB}" \
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--luks2-keyslots-size 16777216 \
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--luks2-metadata-size 4194304 \
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--pbkdf argon2id \
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--sector-size 4096 \
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--type luks2 \
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--use-random \
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--verbose \
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"${LUKSFS}"
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elif [[ "${VAR_CDLB_INSIDE_RUNNER}" == "true" ]]; then
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cryptsetup luksFormat \
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--batch-mode \
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--cipher aes-xts-plain64 \
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--integrity hmac-sha512 \
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--iter-time 1000 \
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--key-file "/proc/$$/fd/${KEYFD}" \
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--key-size 512 \
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--label "${DM_LAB}" \
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--luks2-keyslots-size 16777216 \
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--luks2-metadata-size 4194304 \
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--pbkdf argon2id \
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--sector-size 4096 \
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--type luks2 \
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--use-random \
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--verbose \
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"${LUKSFS}"
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fi
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cryptsetup open --key-file "/proc/$$/fd/${KEYFD}" "${LUKSFS}" "${DM_LAB}"
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# shellcheck disable=SC2155
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declare -i LUKS_FREE=$(blockdev --getsize64 "${DEVMAP}")
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declare -i SQUASH_FS="${VAR_ROOTFS_SIZE}"
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if (( LUKS_FREE >= SQUASH_FS )); then
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printf "\e[92m✅ LUKS_FREE '%s' >= SQUASH_FS '%s' \e[0m\n" "${LUKS_FREE}" "${SQUASH_FS}"
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else
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printf "\e[91m❌ LUKS_FREE '%s' <= SQUASH_FS '%s' \e[0m\n" "${LUKS_FREE}" "${SQUASH_FS}" >&2
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exit 42
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fi
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dd if="${ROOTFS}" of="${DEVMAP}" bs=8M status=progress conv=fsync
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sync
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cryptsetup close "${DM_LAB}"
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exec {KEYFD}<&-
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shred -fzu -n 5 -- "${LUKS_KEY_FILE}"
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rm -f -- "${ROOTFS}"
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umask "${__umask}"
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__umask=""
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printf "\e[92m✅ '%s' applied successfully. \e[0m\n" "${0}"
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exit 0
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# vim: number et ts=2 sw=2 sts=2 ai tw=128 ft=sh
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