CISS.debian.live.builder/config/includes.chroot/usr/lib/live/boot/0024-ciss-crypt-squash

#!/bin/sh
# bashsupport disable=BP5007
# shellcheck disable=SC2249
# shellcheck shell=sh

# SPDX-Version: 3.0
# SPDX-CreationInfo: 2025-11-12; WEIDNER, Marc S.; <msw@coresecret.dev>
# SPDX-ExternalRef: GIT https://git.coresecret.dev/msw/CISS.debian.live.builder.git
# SPDX-FileContributor: WEIDNER, Marc S.; Centurion Intelligence Consulting Agency
# SPDX-FileCopyrightText: 2024-2025; WEIDNER, Marc S.; <msw@coresecret.dev>
# SPDX-FileType: SOURCE
# SPDX-License-Identifier: LicenseRef-CNCL-1.1 OR LicenseRef-CCLA-1.1
# SPDX-LicenseComment: This file is part of the CISS.debian.installer.secure framework.
# SPDX-PackageName: CISS.debian.live.builder
# SPDX-Security-Contact: security@coresecret.eu

# Module summary:
# - Read CISS boot parameters for the encrypted root path and live ISO label.
# - Mount the live medium read-only and locate the encrypted SquashFS container.
# - Attach the encrypted container through a read-only loop device.
# - Accept a LUKS passphrase from the local console or remotely unlock FIFO.
# - Open the decrypted root mapper and expose the handoff state for later live-boot overlay processing.

_SAVED_SET_OPTS="$(set +o)"

set -eu

#######################################
# Ensure the minimal device nodes required by this early boot script exist.
# Globals:
#   None
# Arguments:
#   None
# Returns:
#   0: always, device-node setup is best-effort only
#######################################
ensure_minimal_dev_nodes() {
  mknod_cmd=""
  busybox_cmd=""

  [ -d /dev ] || mkdir -p /dev || return 0

  if [ -c /dev/null ] && [ -c /dev/console ]; then

    return 0

  fi

  mknod_cmd="$(command -v mknod 2>&- || printf '')"
  if [ -z "${mknod_cmd}" ]; then

    busybox_cmd="$(command -v busybox 2>&- || printf '')"

  fi

  if [ ! -c /dev/null ]; then

    rm -f /dev/null || true
    if [ -n "${mknod_cmd}" ]; then

      "${mknod_cmd}" -m 666 /dev/null c 1 3 || true

    elif [ -n "${busybox_cmd}" ]; then

      "${busybox_cmd}" mknod -m 666 /dev/null c 1 3 || true

    fi

  fi

  if [ ! -c /dev/console ]; then

    rm -f /dev/console || true
    if [ -n "${mknod_cmd}" ]; then

      "${mknod_cmd}" -m 600 /dev/console c 5 1 || true

    elif [ -n "${busybox_cmd}" ]; then

      "${busybox_cmd}" mknod -m 600 /dev/console c 5 1 || true

    fi

  fi

  return 0
}

#######################################
# Console logging helper that does not assume /dev/console is always present.
# Globals:
#   None
# Arguments:
#   1: printf format
#   *: printf arguments
# Returns:
#   0: always, logging failure is not fatal
#######################################
console_printf() {
  console_format="$1"
  shift

  if [ -c /dev/console ]; then

    # shellcheck disable=SC2059
    printf "${console_format}" "$@" > /dev/console || :

  elif [ -e /proc/1/fd/1 ]; then

    # shellcheck disable=SC2059
    printf "${console_format}" "$@" > /proc/1/fd/1 || :

  fi

  return 0
}

#######################################
# Clear the current console line without making cleanup fatal.
# Globals:
#   None
# Arguments:
#   None
# Returns:
#   0: always, console cleanup failure is not fatal
#######################################
console_clear_line() {
  console_printf '\r\033[K'

  return 0
}

#######################################
# Wait for an explicit local-console unlock activation.
# Globals:
#   None
# Arguments:
#   None
# Returns:
#   0: local console activation was requested
#   1: console unavailable or activation read failed
#######################################
wait_for_local_unlock_activation() {
  LOCAL_UNLOCK_SAVED_STTY=""
  LOCAL_UNLOCK_READ_STATUS=0

  ensure_minimal_dev_nodes

  [ -c /dev/console ] || return 1
  exec 9<>/dev/console || return 1

  LOCAL_UNLOCK_SAVED_STTY=$(stty -g <&9 2>&- || printf '')
  trap 'if [ -n "${LOCAL_UNLOCK_SAVED_STTY}" ]; then stty "${LOCAL_UNLOCK_SAVED_STTY}" <&9 2>&- || :; fi; printf "\r\033[K" >&9 2>&- || :; exec 9>&-; exit 143' TERM INT HUP

  if [ -n "${LOCAL_UNLOCK_SAVED_STTY}" ]; then

    stty -echo <&9 2>&- || :

  fi

  printf '\e[93m[INFO] Press Enter for local unlock: \e[0m' >&9 || :
  IFS= read -r _ <&9
  LOCAL_UNLOCK_READ_STATUS="$?"

  if [ -n "${LOCAL_UNLOCK_SAVED_STTY}" ]; then

    stty "${LOCAL_UNLOCK_SAVED_STTY}" <&9 2>&- || :

  fi

  printf '\r\033[K' >&9 || :
  exec 9>&-
  trap - TERM INT HUP

  [ "${LOCAL_UNLOCK_READ_STATUS}" -eq 0 ] || return 1

  return 0
}

ensure_minimal_dev_nodes

printf "\e[95m[INFO] Starting             : [/usr/lib/live/boot/0024-ciss-crypt-squash] \n\e[0m"

#######################################
# Ask for a passphrase on /dev/console, mask input with '*'.
# Globals:
#   None
# Arguments:
#   None
# Returns:
#   0: on success
#   1: on failure / empty
#######################################
ask_pass_console() {
  PASSPHRASE=""
  SAVED_STTY=""

  ensure_minimal_dev_nodes

  [ -c /dev/console ] || return 1
  exec 8<>/dev/console || return 1

  ### Save current console settings.
  SAVED_STTY=$(stty -g <&8 2>&- || printf '')

  ### Non-canonical mode, no echo, 1 byte at a time.
  if ! stty -echo -icanon time 0 min 1 <&8 2>&-; then

    exec 8>&-
    return 1

  fi

  cr=$(printf '\r')
  bs=$(printf '\b')
  del=$(printf '\177')

  while :; do

    ### Read exactly one byte from the console.
    c=$(dd bs=1 count=1 2>&- <&8)

    if [ -z "${c}" ]; then

      printf '\n' >&8
      break

    fi

    ### If nothing read (race), loop again.
    [ -z "${c}" ] && continue

    case "${c}" in

      "${cr}")
      ### Enter: finish input.
        printf '\n' >&8
        break
        ;;

      "${bs}"|"${del}")
      ### Backspace, delete: delete one character, if available.
        if [ -n "${PASSPHRASE}" ]; then

          PASSPHRASE=${PASSPHRASE%?}
          printf '\b \b' >&8

        fi
        ;;

      *)
      ### Normal character: append and mask output.
        PASSPHRASE="${PASSPHRASE}${c}"
        printf '*' >&8
        ;;

    esac

  done

  if [ -n "${SAVED_STTY}" ]; then

    stty "${SAVED_STTY}" <&8 2>&- || :

  fi

  exec 8>&-

  printf '%s' "${PASSPHRASE}"

  return 0
}

#######################################
# Premount logging helper.
# Globals:
#   None
# Arguments:
#   *: String to log.
#######################################
log() {
  msg="$*"
  if [ -w /dev/kmsg ]; then
    printf '<6>%s: %s\n' '0024-ciss-crypt-squash' "${msg}" > /dev/kmsg
  else
    printf '%s: %s\n' '0024-ciss-crypt-squash' "${msg}"
  fi
}

### Declare variables. ---------------------------------------------------------------------------------------------------------
export CDLB_ISO_LABEL="CISS.debian.live"
export CDLB_LUKS_FS="/live/ciss_rootfs.crypt"
export CDLB_LUKS_ROOTFS_MNT="/run/live/ciss-rootfs"
export CDLB_MAPPER_NAME="crypt_liveiso"
export CDLB_MAPPER_DEV="/dev/mapper/${CDLB_MAPPER_NAME}"
export CDLB_MNT_MEDIUM="/run/live/medium"
export CDLB_MNT_ROOTFS="/run/live/rootfs"
export CDLB_REMOTE_WAIT_SECS="${CDLB_REMOTE_WAIT_SECS:-3600}"
_PARAMETER=""
_dev=""

### Read the kernel cmdline once. ----------------------------------------------------------------------------------------------
CMDLINE="$(cat /proc/cmdline 2>&- || printf '')"

for _PARAMETER in ${CMDLINE}; do

  case "${_PARAMETER}" in

    ciss_crypt_path=*) export CDLB_LUKS_FS="${_PARAMETER#ciss_crypt_path=}";;
    ciss_iso_label=* ) export CDLB_ISO_LABEL="${_PARAMETER#ciss_iso_label=}";;

  esac

done

printf "\e[92m[INFO] CDLB_LUKS_FS         : [%s] \n\e[0m" "${CDLB_LUKS_FS}"
printf "\e[92m[INFO] CDLB_ISO_LABEL       : [%s] \n\e[0m" "${CDLB_ISO_LABEL}"

mkdir -p /conf "${CDLB_MNT_MEDIUM}" "${CDLB_MNT_ROOTFS}"

### Mount the live medium (ISO) read-only, unless already mounted. -------------------------------------------------------------
if ! mountpoint -q "${CDLB_MNT_MEDIUM}"; then

  if [ -n "${CDLB_ISO_LABEL}" ] && [ -e "/dev/disk/by-label/${CDLB_ISO_LABEL}" ]; then

    mount -r -t iso9660 "/dev/disk/by-label/${CDLB_ISO_LABEL}" "${CDLB_MNT_MEDIUM}" 2>&- \
      || mount -r -t udf "/dev/disk/by-label/${CDLB_ISO_LABEL}" "${CDLB_MNT_MEDIUM}" 2>&- \
      || log "could not mount label=${CDLB_ISO_LABEL} (iso9660/udf)"

  fi

fi

if ! mountpoint -q "${CDLB_MNT_MEDIUM}"; then

  ### Fallback scan (covers SR drives and loop-mounted ISOs that udev exposed).
  for _dev in /dev/sr* /dev/cdrom /dev/disk/by-label/*; do

    ### Skip non-block entries early.
    [ -b "${_dev}" ] || continue

    ### Try ISO9660 first, then UDF; only unmount on failure.
    if mount -r -t iso9660 "${_dev}" "${CDLB_MNT_MEDIUM}" 2>&- || mount -r -t udf   "${_dev}" "${CDLB_MNT_MEDIUM}" 2>&-; then

      mountpoint -q "${CDLB_MNT_MEDIUM}" 2>&- && break

    else

      umount "${CDLB_MNT_MEDIUM}" 2>&- || true

    fi

  done

fi

if ! mountpoint -q "${CDLB_MNT_MEDIUM}"; then

  printf "\e[91m[FATAL] Boot failure        : No live medium mounted, defer to default live-boot path. \n\e[0m"
  sleep 60
  log   "[FATAL] Boot failure        : No live medium mounted, defer to default live-boot path."
  panic "[FATAL] Boot failure        : No live medium mounted, defer to default live-boot path."

fi

printf "\e[92m[INFO] MNT_MEDIUM           : [%s] \n\e[0m" "${CDLB_MNT_MEDIUM}"

### Locate the encrypted root container on the medium. -------------------------------------------------------------------------
if [ ! -f "${CDLB_MNT_MEDIUM}${CDLB_LUKS_FS}" ]; then

  printf "\e[91m[FATAL] Boot failure        : Encrypted root not found at: [%s%s] \n\e[0m" "${CDLB_MNT_MEDIUM}" "${CDLB_LUKS_FS}"
  sleep 60
  log   "[FATAL] Boot failure        : Encrypted root not found at: [${CDLB_MNT_MEDIUM}${CDLB_LUKS_FS}]"
  panic "[FATAL] Boot failure        : Encrypted root not found at: [${CDLB_MNT_MEDIUM}${CDLB_LUKS_FS}]"

fi

printf "\e[92m[INFO] CISS LUKS FS         : [%s%s] \n\e[0m" "${CDLB_MNT_MEDIUM}" "${CDLB_LUKS_FS}"

### Attach a loop device read-only to the encrypted file. ----------------------------------------------------------------------
if ! LOOP="$(losetup -f --show -r "${CDLB_MNT_MEDIUM}${CDLB_LUKS_FS}")"; then

  printf "\e[91m[FATAL] Boot failure        : losetup failed \n\e[0m"
  sleep 60
  log   "[FATAL] Boot failure        : losetup failed "
  panic "[FATAL] Boot failure        : losetup failed "

fi

printf "\e[92m[INFO] Loop device          : [%s] \n\e[0m" "${LOOP}"

### Expose the loop device for unlock-wrapper.sh, dropbear forced-command. -----------------------------------------------------
mkdir -p /run 2>&- || true

echo "${LOOP}" > /run/ciss-loopdev 2>&- || true

chmod 0600 /run/ciss-loopdev 2>&- || true

printf "\e[92m[INFO] Exposed LOOP         : [/run/ciss-loopdev] -> [%s]\n\e[0m" "${LOOP}"

### Prepare fifo for passphrase. -----------------------------------------------------------------------------------------------
mkdir -p /lib/cryptsetup 2>&- || true

if [ -p /lib/cryptsetup/passfifo ]; then

  rm -f /lib/cryptsetup/passfifo 2>&- || true

fi

if ! mkfifo /lib/cryptsetup/passfifo 2>&-; then

  printf "\e[92m[WARN] Boot failure         : Failed to create [/lib/cryptsetup/passfifo] \n\e[0m"
  sleep 60
  log   "[WARN] Boot failure         : Failed to create [/lib/cryptsetup/passfifo]"
  panic "[WARN] Boot failure         : Failed to create [/lib/cryptsetup/passfifo]"

fi

chmod 0600 /lib/cryptsetup/passfifo 2>&- || true

### Background broker: read FIFO, try cryptsetup per line. ---------------------------------------------------------------------
(
  set +e

  PASS=""

  while :; do

    if [ -b "${CDLB_MAPPER_DEV}" ]; then

      break

    fi

    if ! IFS= read -r PASS < /lib/cryptsetup/passfifo; then

      sleep 1
      continue

    fi

    [ -n "${PASS}" ] || continue

    console_printf "\e[93m[INFO] CISS LUKS decryption : LUKS mapper [%s] trying to unlock via cryptsetup ... \n\e[0m" "${CDLB_MAPPER_DEV}"

    KEYLEN=${#PASS}

    if [ -c /dev/console ]; then

      printf '%s' "${PASS}" | cryptsetup open --tries 1 \
        --type luks \
        --keyfile-size="${KEYLEN}" \
        --readonly "${LOOP}" "${CDLB_MAPPER_NAME}" --key-file - 2>/dev/console

    else

      printf '%s' "${PASS}" | cryptsetup open --tries 1 \
        --type luks \
        --keyfile-size="${KEYLEN}" \
        --readonly "${LOOP}" "${CDLB_MAPPER_NAME}" --key-file - 2>&-

    fi

    if [ -b "${CDLB_MAPPER_DEV}" ]; then

      console_printf "\e[92m[INFO] CISS LUKS decryption : LUKS mapper [%s] successfully opened. \n\e[0m" "${CDLB_MAPPER_DEV}"
      break

    fi

  done
) &
PID_BROKER="$!"

### Background process console-prompt feed passphrases into FIFO. --------------------------------------------------------------
(
  set +e

  PASS=""
  PASS_SENT=0
  WAIT_LOOP=0

  while :; do

    if [ -b "${CDLB_MAPPER_DEV}" ]; then

      break

    fi

    if [ "${PASS_SENT}" -eq 0 ]; then

      # shellcheck disable=SC2310
      wait_for_local_unlock_activation || continue

      console_printf '\e[93m[INFO] Enter LUKS passphrase: \n\e[0m'

      # shellcheck disable=SC2310
      PASS="$(ask_pass_console)" || continue

      printf '%s\n' "${PASS}" >| /lib/cryptsetup/passfifo 2>&- || :

      PASS_SENT=1
      WAIT_LOOP=0

    else

      WAIT_LOOP=$((WAIT_LOOP + 1))

      if [ "${WAIT_LOOP}" -ge 160 ]; then

        console_printf '\e[91m[WARN] Please try again     : \n\e[0m'

        PASS_SENT=0
        WAIT_LOOP=0

      fi

    fi

    sleep 0.1

  done

  return 0
) &
PID_PROMPT="$!"

### Main process: wait bounded time for the mapper to appear. ------------------------------------------------------------------
REMAINING="${CDLB_REMOTE_WAIT_SECS}"

if [ ! -b "${CDLB_MAPPER_DEV}" ]; then

  printf "\e[93m[INFO] CISS LUKS decryption : Waiting up to %s seconds for [%s] to be unlocked ... \n\e[0m" "${REMAINING}" "${CDLB_MAPPER_DEV}"

fi

while [ "${REMAINING}" -gt 0 ]; do

  if [ -b "${CDLB_MAPPER_DEV}" ]; then

    break

  fi

  sleep 1

  REMAINING=$((REMAINING - 1))

done

if [ ! -b "${CDLB_MAPPER_DEV}" ]; then

  printf "\e[91m[WARN] CISS LUKS decryption : Timeout LUKS mapper [%s] not present after %s seconds. \n\e[0m" "${CDLB_MAPPER_DEV}" "${CDLB_REMOTE_WAIT_SECS}"

  kill "${PID_PROMPT}" 2>&- || true
  kill "${PID_BROKER}" 2>&- || true
  wait "${PID_PROMPT}" 2>&- || true
  wait "${PID_BROKER}" 2>&- || true
  console_clear_line

  rm -f /lib/cryptsetup/passfifo 2>&- || true

  sleep 60

  log   "[WARN] CISS LUKS decryption : Timeout LUKS mapper [${CDLB_MAPPER_DEV}] not present after ${CDLB_REMOTE_WAIT_SECS} seconds."
  panic "[WARN] CISS LUKS decryption : Timeout LUKS mapper [${CDLB_MAPPER_DEV}] not present after ${CDLB_REMOTE_WAIT_SECS} seconds."

fi

kill "${PID_PROMPT}" 2>&- || true
kill "${PID_BROKER}" 2>&- || true
wait "${PID_PROMPT}" 2>&- || true
wait "${PID_BROKER}" 2>&- || true
console_clear_line

rm -f /lib/cryptsetup/passfifo 2>&- || true

printf "\e[92m[INFO] CISS LUKS decryption : [%s] is now present.\n\e[0m" "${CDLB_MAPPER_DEV}"

### Expose the decrypted root device for live-boot overlay. The live-boot components will pick this up in '9990-overlay.sh'. ---
cat << EOF >| /run/ciss-rootdev
export CDLB_ISO_LABEL=${CDLB_ISO_LABEL}
export CDLB_LUKS_FS=${CDLB_LUKS_FS}
export CDLB_LUKS_ROOTFS_MNT=${CDLB_LUKS_ROOTFS_MNT}
export CDLB_MAPPER_NAME=${CDLB_MAPPER_NAME}
export CDLB_MAPPER_DEV=${CDLB_MAPPER_DEV}
export CDLB_MNT_MEDIUM=${CDLB_MNT_MEDIUM}
export CDLB_MNT_ROOTFS=${CDLB_MNT_ROOTFS}
export CDLB_REMOTE_WAIT_SECS=${CDLB_REMOTE_WAIT_SECS}
EOF
chmod 0444 /run/ciss-rootdev 2>&- || true

### Override '9990-main.sh' behavior to ensure 'Verify_checksums()' functions properly. ----------------------------------------
if [ ! -e /conf/param.conf ]; then

  printf "\e[92m[INFO] CISS LUKS decryption : Not existing [/conf/param.conf] \n\e[0m"
  : >| /conf/param.conf

fi

if ! grep -q '^PLAIN_ROOT=' /conf/param.conf 2>&-; then

  printf 'PLAIN_ROOT=1\n' >> /conf/param.conf

fi

if ! grep -q '^livefs_root=' /conf/param.conf 2>&-; then

  printf 'livefs_root=%s\n' "/run/live/medium" >> /conf/param.conf

fi

printf "\e[92m[INFO] CISS LUKS decryption : Final state [/conf/param.conf] \n\e[0m"
if [ -c /dev/console ]; then

  cat /conf/param.conf >/dev/console 2>&1 || :

elif [ -e /proc/1/fd/1 ]; then

  cat /conf/param.conf >/proc/1/fd/1 2>&1 || :

fi

log "Decrypted root device exposed at [/run/ciss-rootdev] -> [${CDLB_MAPPER_DEV}]"
printf "\e[92m[INFO] CISS LUKS decryption : Decrypted root device exposed at: [/run/ciss-rootdev] -> [%s] \n\e[0m" "${CDLB_MAPPER_DEV}"

### Final sanity check. --------------------------------------------------------------------------------------------------------
if [ ! -b "${CDLB_MAPPER_DEV}" ]; then

  printf "\e[91m[WARN] Failed unlock        : [%s] via dropbear and console. \n\e[0m" "${CDLB_LUKS_FS}"
  sleep 60
  log   "[WARN] Failed unlock        : [${CDLB_LUKS_FS}] via dropbear and console."
  panic "[WARN] Failed unlock        : [${CDLB_LUKS_FS}] via dropbear and console."

fi

eval "${_SAVED_SET_OPTS}"

printf "\e[92m[INFO] Successfully applied : [/usr/lib/live/boot/0024-ciss-crypt-squash] \n\e[0m"

# vim: number et ts=2 sw=2 sts=2 ai tw=128 ft=sh