Marc S. Weidner
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Signed-off-by: Marc S. Weidner <msw@coresecret.dev>
397 lines
11 KiB
Bash
397 lines
11 KiB
Bash
#!/bin/bash
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# SPDX-Version: 3.0
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# SPDX-CreationInfo: 2025-06-17; WEIDNER, Marc S.; <msw@coresecret.dev>
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# SPDX-ExternalRef: GIT https://git.coresecret.dev/msw/CISS.debian.installer.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: EUPL-1.2 OR LicenseRef-CCLA-1.0
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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.installer
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# SPDX-Security-Contact: security@coresecret.eu
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# SPDX-Comment: unlock_wrapper.sh to be executed as '/etc/crypttab' keyscript and as dropbear SSH forced command.
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set -Ceuo pipefail
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#######################################
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# Variable declaration
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#######################################
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declare -r ASKPASS='/lib/cryptsetup/askpass'
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declare -r REGEX='^\$[a-z0-9]+\$[./A-Za-z0-9]+\$[./A-Za-z0-9]+$'
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# shellcheck disable=SC2155
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declare -r CURRENTDATE=$(date +"%F %T")
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declare -r GRE='\e[0;92m'
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declare -r MAG='\e[0;95m'
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declare -r RED='\e[0;91m'
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declare -r RES='\e[0m'
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declare -r NL='\n'
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declare -g NUKE_ENABLED='false'
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declare -g NUKE_HASH=''
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declare -g PASSPHRASE=''
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#######################################
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# Print-colored text.
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# Arguments:
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# 1: Color code.
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# *: Text to print.
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#######################################
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color_echo() { declare c="$1"; shift; declare msg="${*}"; printf "%s%s %s%s" "${c}" "${msg}" "${RES}" "${NL}"; }
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#######################################
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# Die helper: print and exit hard.
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# Globals:
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# NC
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# RED
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# Arguments:
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# 1: Message string to print.
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#######################################
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die() { printf "%s✘ %s %s%s" "${RED}" "$1" "${RES}" "${NL}" >&2; power_off 3; }
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#######################################
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# Drop to bash environment.
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# Arguments:
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# None
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#######################################
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drop_bash() { stty echo; prompt_string; exec /bin/bash -i; }
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#######################################
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# Extract the 'nuke='-parameter from '/proc/cmdline'.
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# Globals:
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# NUKE_ENABLED
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# NUKE_HASH
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# RED
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# Arguments:
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# None
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# Returns:
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# 0: if 'nuke=' was found and extracted.
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# 1: if not found.
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#######################################
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extract_nuke_hash() {
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declare ARG="" CMDLINE=""
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### Read '/proc/cmdline' into a single line safely.
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read -r CMDLINE < /proc/cmdline
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for ARG in ${CMDLINE}; do
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case "${ARG}" in
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nuke=*)
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NUKE_HASH="${ARG#nuke=}"
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if [[ "${NUKE_HASH}" =~ ${REGEX} ]]; then
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NUKE_ENABLED="true"
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return 0
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else
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### If there is a malformed Grub Bootparameter 'nuke=HASH', drop to bash.
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color_echo "${RED}" "✘ Nuke Hash Malformat : [${REGEX}] [${NUKE_HASH}]." >&2
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color_echo "${RED}" "✘ Dropping to bash ...:" >&2
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drop_bash
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fi
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;;
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esac
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done
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### No 'nuke=HASH' entry found.
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return 1
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}
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#######################################
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# Gather information of all LUKS Devices available on the system.
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# Arguments:
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# None
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#######################################
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gather_luks_devices() {
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declare prev=() curr=()
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declare -i tries=0
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while ((tries < 10)); do
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# shellcheck disable=SC2312
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mapfile -t curr < <(blkid -t TYPE=crypto_LUKS -o device | sort)
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if cmp <(printf '%s\n' "${curr[@]}") <(printf '%s\n' "${prev[@]}") >/dev/null; then
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break
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fi
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prev=("${curr[@]}")
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tries=$((tries + 1))
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sleep 1
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done
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printf '%s\n' "${curr[@]}"
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}
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#######################################
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# Erase LUKS headers on all LUKS devices and shutdown system.
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# Globals:
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# DEVICES_LUKS
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# RED
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# Arguments:
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# None
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#######################################
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nuke() {
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declare dev=""
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for dev in "${DEVICES_LUKS[@]}"; do
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cryptsetup erase --batch-mode "${dev}" || true
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color_echo "${RED}" "✘ Error: LUKS Device Header malfunction: [${dev}]."
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done
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secure_unset_pass
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color_echo "${RED}" "✘ Error: LUKS Device malfunction. System Power Off in 16 seconds."
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power_off 16
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}
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#######################################
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# Unified power-off routine.
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# Arguments:
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# 1: Sleep time before power-off in seconds (Default to 0 seconds).
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#######################################
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power_off() {
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declare -r wait="${1:-0}"
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sleep "${wait}"
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sync
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echo 1 >| /proc/sys/kernel/sysrq
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echo o >| /proc/sysrq-trigger
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### The System powers off immediately; no further code is executed.
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}
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#######################################
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# Print Error Message for Trap on 'ERR' on Terminal.
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# Globals:
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# NL
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# RED
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# Arguments:
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# 1: ${?}
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# 2: ${BASH_SOURCE[0]}
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# 3: ${LINENO}
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# 4: ${FUNCNAME[0]:-main}
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# 5: ${BASH_COMMAND}
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#######################################
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print_scr_err() {
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declare -r scr_err_errcode="$1"
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declare -r scr_err_errscrt="$2"
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declare -r scr_err_errline="$3"
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declare -r scr_err_errfunc="$4"
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declare -r scr_err_errcmmd="$5"
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printf "%s" "${NL}"
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color_echo "${RED}" "✘ System caught an 'ERROR'. System Power Off in 16 seconds." >&2
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printf "%s" "${NL}"
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color_echo "${RED}" "✘ Error : [${scr_err_errcode}]" >&2
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color_echo "${RED}" "✘ Line : [${scr_err_errline}]" >&2
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color_echo "${RED}" "✘ Script : [${scr_err_errscrt}]" >&2
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color_echo "${RED}" "✘ Function : [${scr_err_errfunc}]" >&2
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color_echo "${RED}" "✘ Command : [${scr_err_errcmmd}]" >&2
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printf "%s" "${NL}"
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}
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#######################################
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# Print Error Message for '0'-Exit-Code on Terminal.
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# Globals:
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# GRE
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# Arguments:
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# None
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#######################################
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print_scr_scc() { color_echo "${GRE}" "✅ Script exited successfully. Proceeding with booting."; }
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#######################################
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# Generates informative shell prompt.
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# Globals:
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# PS1
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# Arguments:
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# None
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#######################################
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prompt_string() {
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declare -gx PS1="\
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\[\033[1;91m\]\d\[\033[0m\]|\[\033[1;91m\]\u\[\033[0m\]@\
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\[\033[1;95m\]\h\[\033[0m\]:\
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\[\033[1;96m\]\w\[\033[0m\]/>>\
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\$(if [[ \$? -eq 0 ]]; then \
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# Show exit status in green if zero
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echo -e \"\[\033[1;92m\]\$?\[\033[0m\]\"; \
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else \
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# Show exit status in red otherwise
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echo -e \"\[\033[1;91m\]\$?\[\033[0m\]\"; \
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fi)\
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|~\$ "
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}
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#######################################
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# Read Passphrase interactively.
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# Globals:
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# ASKPASS
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# NUKE_ENABLED
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# NUKE_HASH
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# PASSPHRASE
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# Arguments:
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# None
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# Returns:
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# 0: on success
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#######################################
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read_passphrase() {
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declare -a METHODS=("sha512crypt" "yescrypt" "scrypt" "bcrypt")
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declare METHOD="" SALT=""
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PASSPHRASE="$(${ASKPASS} "Enter passphrase: ")"
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if [[ "${NUKE_ENABLED,,}" == 'true' ]]; then
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### Validate NUKE_HASH format (e.g., $id$salt$hash)
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if [[ "${NUKE_HASH}" =~ ${REGEX} ]]; then
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SALT="$(cut -d'$' -f3 <<< "${NUKE_HASH}")"
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for METHOD in "${METHODS[@]}"; do
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if mkpasswd -m "${METHOD}" -S "${SALT}" "${PASSPHRASE}" 2>/dev/null | grep -qF -- "${NUKE_HASH}"; then
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nuke
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fi
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done
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fi
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fi
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return 0
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}
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#######################################
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# Securely unset the passphrase variable.
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# Globals:
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# PASSPHRASE
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# Arguments:
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# None
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#######################################
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secure_unset_pass() { unset PASSPHRASE; PASSPHRASE=""; }
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#######################################
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# Trap function to be called on 'ERR'.
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# Arguments:
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# 1: ${?}
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# 2: ${BASH_SOURCE[0]}
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# 3: ${LINENO}
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# 4: ${FUNCNAME[0]:-main}
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# 5: ${BASH_COMMAND}
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#######################################
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trap_on_err() {
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declare -r errcode="$1"
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declare -r errscrt="$2"
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declare -r errline="$3"
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declare -r errfunc="$4"
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declare -r errcmmd="$5"
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trap - ERR INT TERM
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stty echo
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print_scr_err "${errcode}" "${errscrt}" "${errline}" "${errfunc}" "${errcmmd}"
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power_off 16
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}
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#######################################
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# Security Trap on 'INT' and 'TERM' to provide a deterministic way to not circumvent the nuke routine.
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# Globals:
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# NL
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# RED
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# Arguments:
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# None
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#######################################
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trap_on_term() {
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trap - ERR INT TERM
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stty echo
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printf "%s" "${NL}"
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color_echo "${RED}" "✘ Received termination signal. System Power Off in 3 seconds." >&2
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power_off 3
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}
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#######################################
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# Check the integrity and authenticity of this script itself.
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# Globals:
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# GRE
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# MAG
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# RED
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# Arguments:
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# 0: Script Name
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#######################################
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verify_script() {
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declare dir
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# shellcheck disable=SC2312
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dir="$(dirname "$(readlink -f "${0}")")"
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declare script; script="$(basename "${0}")"
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declare -a algo=("sha512" "sha384")
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declare cmd="" computed="" expected="" hashfile="" item="" sigfile=""
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for item in "${algo[@]}"; do
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hashfile="${dir}/${script}.${item}"
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sigfile="${hashfile}.sig"
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cmd="${item}sum"
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color_echo "${MAG}" "🔏 Verifying signature of: [${hashfile}]"
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gpgv --keyring /etc/keys/pubring.gpg "${sigfile}" "${hashfile}" || {
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color_echo "${RED}" "✘ Signature verification failed for: [${hashfile}]"
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color_echo "${RED}" "✘ System Power Off in 3 seconds ...."
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power_off 3
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}
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color_echo "${GRE}" "🔏 Verifying signature of: [${hashfile}] successful."
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color_echo "${MAG}" "🔢 Recomputing Hash: [${item}]"
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computed=$(${cmd} "${dir}/${script}" | awk '{print $1}')
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expected=$(cat "${hashfile}")
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if [[ "${computed}" != "${expected}" ]]; then
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color_echo "${RED}" "✘ Recomputed hash mismatch for : [${item}]" >&2
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color_echo "${RED}" "✘ System Power Off in 3 seconds ...." >&2
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power_off 3
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fi
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color_echo "${GRE}" "🔢 Recomputing Hash: [${item}] successful."
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done
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color_echo "${GRE}" "🔏 All signatures and hashes verified successfully. Proceeding."
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}
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#######################################
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# Main Program Sequence
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# Globals:
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# CURRENTDATE
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# DEVICES_LUKS
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# GRE
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# MAG
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# NL
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# PASSPHRASE
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# RED
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# Arguments:
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# None
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#######################################
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main() {
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trap 'trap_on_err "$?" "${BASH_SOURCE[0]}" "${LINENO}" "${FUNCNAME[0]:-main}" "${BASH_COMMAND}"' ERR
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trap 'trap_on_term' INT TERM
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color_echo "${RED}" "Coresecret Connection established."
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color_echo "${RED}" "Starting Time: ${CURRENTDATE}"
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color_echo "${MAG}" "Integrity self-check ..."
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printf "%s" "${NL}"
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verify_script
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### Read newline-separated output into an array.
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color_echo "${MAG}" "Scanning for LUKS devices ..."
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printf "%s" "${NL}"
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# shellcheck disable=SC2312
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mapfile -t DEVICES_LUKS < <(gather_luks_devices)
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### If there are no LUKS devices at all, drop to bash.
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if (( ${#DEVICES_LUKS[@]} == 0 )); then
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color_echo "${RED}" "✘ No LUKS Devices found. Dropping to bash ..."
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drop_bash
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fi
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### Extract the 'nuke='-parameter from '/proc/cmdline'.
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extract_nuke_hash
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### Read passphrase interactively.
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read_passphrase
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if printf "%s" "${PASSPHRASE}" | cryptroot-unlock; then
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secure_unset_pass
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exit 0
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else
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printf "%s" "${NL}"
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color_echo "${RED}" "✘ Unsuccessful command 'cryptroot-unlock'."
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color_echo "${GRE}" "✘ No LUKS operations performed. Dropping to bash ..."
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color_echo "${GRE}" "✘ To unlock 'root' partition, and maybe others like 'swap', run 'cryptroot-unlock'."
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drop_bash
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fi
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}
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main "${@}"
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# vim: number et ts=2 sw=2 sts=2 ai tw=128 ft=sh
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