#!/bin/bash
# SPDX-Version: 3.0
# SPDX-CreationInfo: 2025-06-17; WEIDNER, Marc S.; <msw@coresecret.dev>
# SPDX-ExternalRef: GIT https://git.coresecret.dev/msw/CISS.debian.installer.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: EUPL-1.2 OR LicenseRef-CCLA-1.0
# SPDX-LicenseComment: This file is part of the CISS.debian.installer.secure framework.
# SPDX-PackageName: CISS.debian.installer
# SPDX-Security-Contact: security@coresecret.eu

guard_sourcing

#######################################
# Hardening 'ufw'.
# Globals:
#   TARGET
#   VAR_SSH_PORT
#   VAR_UFW_OUT
# Arguments:
#   None
# Returns:
#   0: on success
#######################################
hardening_ufw() {
  ### Declare Arrays, HashMaps, and Variables.
  declare -r  var_logfile="/root/.ciss/cdi/log/4470_hardening_ufw.log"
  declare -r  var_rules="${TARGET}/etc/ufw/before6.rules"

  chroot_logger "${TARGET}${var_logfile}"

  if [[ ! -f "${TARGET}/var/log/ufw.log" ]]; then
    touch "${TARGET}/var/log/ufw.log"
    chmod 0640 "${TARGET}/var/log/ufw.log"
  fi

  chroot_script "${TARGET}" "
    ufw --force reset
    ufw logging medium
    ufw default deny incoming
    ufw default ${VAR_UFW_OUT} outgoing
    ufw default deny forward
    ufw allow in ${VAR_SSH_PORT}/tcp comment 'Incoming SSH'
    ufw limit ${VAR_SSH_PORT}/tcp comment 'Incoming SSH'
  "

  ### Ensure that a standard set of the most commonly used ports are open if a default-'deny'-outbound policy is selected.
  if [[ "${VAR_UFW_OUT}" = "deny" ]]; then

    chroot_script "${TARGET}" "
      ufw allow out   21/tcp comment 'Outgoing FTP'
      ufw allow out   22/tcp comment 'Outgoing SSH'
      ufw allow out   25/tcp comment 'Outgoing SMTP'
      ufw allow out   53/tcp comment 'Outgoing DNS'
      ufw allow out   80/tcp comment 'Outgoing HTTP'
      ufw allow out  123/tcp comment 'Outgoing NTP'
      ufw allow out  143/tcp comment 'Outgoing IMAP'
      ufw allow out  443/tcp comment 'Outgoing HTTPS'
      ufw allow out  465/tcp comment 'Outgoing SMTPS'
      ufw allow out  587/tcp comment 'Outgoing SMTPS'
      ufw allow out  993/tcp comment 'Outgoing IMAPS'
      ufw allow out 4460/tcp comment 'Outgoing NTS'
      ufw allow out ${VAR_SSH_PORT}/tcp comment 'Outgoing SSH'
      ufw allow out   53/udp comment 'Outgoing DNS'
      ufw allow out  123/udp comment 'Outgoing NTP'
      ufw allow out  443/udp comment 'Outgoing QUIC'
      ufw allow out  853/udp comment 'Outgoing DoQ'
    "

  fi

  ### Allowing ICMP IPv4 outgoing per default.
  sed -i "/# ok icmp code for FORWARD/i \# ok icmp codes for OUTPUT" "${TARGET}/etc/ufw/before.rules"
  sed -i "/# ok icmp code for FORWARD/i \-A ufw-before-output -p icmp --icmp-type destination-unreachable -j ACCEPT" "${TARGET}/etc/ufw/before.rules"
  sed -i "/# ok icmp code for FORWARD/i \-A ufw-before-output -p icmp --icmp-type time-exceeded -j ACCEPT" "${TARGET}/etc/ufw/before.rules"
  sed -i "/# ok icmp code for FORWARD/i \-A ufw-before-output -p icmp --icmp-type parameter-problem -j ACCEPT" "${TARGET}/etc/ufw/before.rules"
  sed -i "/# ok icmp code for FORWARD/i \-A ufw-before-output -p icmp --icmp-type echo-request -j ACCEPT" "${TARGET}/etc/ufw/before.rules"


  ### Remove previous custom blocks (idempotent).
  sed -i "/^# BEGIN custom MLD rules/,/^# END custom MLD rules/d" "${var_rules}"
  sed -i "/^# BEGIN custom MLD OUTPUT rules/,/^# END custom MLD OUTPUT rules/d" "${var_rules}"

  ### Inbound MLD (INPUT chain), insert before the existing echo-request rule.
  ### Allows MLDv1 (130/131/132) and MLDv2 (143) to link-local multicast (ff02::/16)
  sed -i "/-A ufw6-before-input .*--icmpv6-type echo-request -j ACCEPT/i # BEGIN custom MLD rules\n-A ufw6-before-input -i ${VAR_FINAL_NIC} -p icmpv6 --icmpv6-type 130 -d ff02::/16 -j ACCEPT\n-A ufw6-before-input -i ${VAR_FINAL_NIC} -p icmpv6 --icmpv6-type 131 -d ff02::/16 -j ACCEPT\n-A ufw6-before-input -i ${VAR_FINAL_NIC} -p icmpv6 --icmpv6-type 132 -d ff02::/16 -j ACCEPT\n-A ufw6-before-input -i ${VAR_FINAL_NIC} -p icmpv6 --icmpv6-type 143 -d ff02::/16 -j ACCEPT\n# END custom MLD rules" "${var_rules}"

  ### Outbound MLD (OUTPUT chain), insert before echo-request.
  ### Useful if local daemons join multicast groups, and you want clean logs.
  sed -i "/-A ufw6-before-output .*--icmpv6-type echo-request -j ACCEPT/i # BEGIN custom MLD OUTPUT rules\n-A ufw6-before-output -o ${VAR_FINAL_NIC} -p icmpv6 --icmpv6-type 131 -d ff02::/16 -j ACCEPT\n-A ufw6-before-output -o ${VAR_FINAL_NIC} -p icmpv6 --icmpv6-type 143 -d ff02::/16 -j ACCEPT\n# END custom MLD OUTPUT rules" "${var_rules}"


  chroot_script "${TARGET}" "echo 'y' | ufw enable 2>&1"

  chroot_script "${TARGET}" "ufw status verbose >> ${var_logfile}"

  guard_dir && return 0
}
### Prevents accidental 'unset -f'.
# shellcheck disable=SC2034
readonly -f hardening_ufw
# vim: number et ts=2 sw=2 sts=2 ai tw=128 ft=sh