#!/bin/bash
#
# Name: pam_panic_config
# Description: Create a pam_panic configuration.
# Author: Bandie <bandie@chaospott.de>
#

CONFIGFILE="/etc/pam.d/pampanic"
LHBU="$HOME/LUKSHeaderBackup"

# Set on build time
SECUREDIR="__SECURELIBDIR__"

if [ $EUID -ne 0 ]; then
  echo "Please run this script as root or using sudo."
  exit 1
fi


# Call when using the Cancel button
function cancel(){
  rm -f .pam_panic_media_choice
  clear
  echo "Bye! :)"
  exit 0
}

# Call when CTRL+C
trap "cancel" INT


# Check, if $1 is a gpt formatted device
function checkGPT(){
  blkid $1 -t PTTYPE=gpt >> /dev/null
  return $?
}


# Get the GPT PartitionUUID
function getPARTUUID(){
  blkid $1 | awk '{print $4;}' | sed 's/PARTUUID="//;s/"//'
}


# Get the LUKS-Device's UUId
function getLUKSDevice(){
  if [ "$1" = "UUID" ]; then
    blkid /dev/sda*[1-9] | grep "crypto_LUKS" | awk '{print $2;}' | sed 's/UUID="//;s/"//'
  fi
  if [ "$1" = "NAME" ]; then
    blkid /dev/sda*[1-9] | grep "crypto_LUKS" | awk '{print $1;}' | sed 's/://'
  fi
}


# Generic dialog question
function ask(){
  dialog --backtitle "pam_panic's Configuration Generator" --title "$1"  --yesno "$2" 8 80
  return $?
}


# Generic message box
msg() {
  dialog --backtitle "pam_panic's Configuration Generator" --title "$1" --msgbox "$2" 8 80
}


# Generate a two dimensional flat array of all GPT devices from sdb-sdz
function getMediaDevice(){
  local i=0
  local uuid
  for dev in $(ls /dev/sd[b-z] 2> /dev/null); do
    if $(checkGPT $dev); then
      for part in $(ls $dev*[1-9]); do
        echo -n "$i $part[$(getPARTUUID $part)] "
        (( i++ ))
      done
    fi
  done
}


# Hint for GPT formatted key before searching for it 
function chooseMediumPre(){
  local title="Removable media: $1 device"

  dialog --backtitle "pam_panic's Configuration Generator" --title "$title" --yes-label "OK" --no-label "Cancel" --yesno "Please remove all media devices before your continue.\nNote, if you device doesn't show up it might not be a GPT formatted device.\n\nPlease insert the device you want to use as $1 device and press OK." 10 80
  if [ $? -eq 1 ]; then
    cancel
  fi
}


# Choosing a GPT formatted key
function chooseMedium(){
  local ans 
  local title="Removable media: $1 device"

  dialog --backtitle "pam_panic's Configuration Generator" --title "$title" --menu "Choose your device:" 10 80 5 $media 2> .pam_panic_media_choice
  if [ $? -eq 1 ]; then
    cancel
  fi

  ans=$(cat .pam_panic_media_choice)
  (( ans=(2*ans)+1 ))
  rm -f .pam_panic_media_choice

  return $ans
}


# A "Detecting devices...", assures to use a more up to date device list
function showDetectDev(){
  dialog --backtitle "pam_panic's Configuration Generator" \
    --title "$title" \
    --infobox "Detecting devices..." 3 80
  # Prevention for impatient beings
  sleep 2
}


# Welcome
dialog --backtitle "pam_panic's Configuration Generator" \
  --title "Welcome" \
  --ok-label "Yip!" \
  --msgbox "Welcome to pam_panic's Configuration Generator.\n\nIt will help you to create a valid pam_panic setup. It will also generate a Linux' PAM configuration file.\n\nAfter you're done with this Configuration Generator, you will see some hints how to integrate the new PAM configuration file in your system." 20 80


# Authentication mode
auth_mode=2
while [ $auth_mode -eq 2 ]; do

  dialog --backtitle "pam_panic's Configuration Generator" \
    --title "Authentication mode" \
    --help-button \
    --extra-button --extra-label "Passwords" \
    --ok-label "Removable Media" \
    --yesno "You can choose between the \"two removable media\" option and the \"two passwords\" option.\nSee \"Help\" to learn what it is.\n\nRemovable media or passwords?" 10 80

  auth_mode=$?

  case $auth_mode in
    "0")
      # Removable media
      # Authentication
      while [ -z $media ]; do
        chooseMediumPre Authentication
        showDetectDev
        media=$(getMediaDevice)
        read -r -a mediaArray <<< "$media"
      done    
      chooseMedium Authentication
      auth_dev=$(echo ${mediaArray[$?]} | sed 's/\/dev\/sd[b-z]*[0-1]\[//;s/\]//')
      msg "Removable media: Authentication device" "Authentication device chosen with UUID $auth_dev."

      # Panic
      unset media
      while [ -z $media ]; do
        chooseMediumPre Panic
        showDetectDev
        media=$(getMediaDevice)
        read -r -a mediaArray <<< "$media"
      done
      chooseMedium Panic
      panic_dev=$(echo ${mediaArray[$?]} | sed 's/\/dev\/sd[b-z]*[0-1]\[//;s/\]//')
      msg "Removable media: Panic device" "Panic device chosen with UUID $panic_dev."

      ;;
    "3")
      # Passwords
      ask "Passwords" "Do you want to set the passwords now?"
      setpw=$?
      case $setpw in
          "0")
            clear
            pam_panic_pw
            if [ $? -ne 0 ]; then
              clear
              echo "Failed to set a password. :("
              exit 1
            fi
            ;;
      esac
      ;;
    "2")
      # Help
      man pam_panic
      ;;
    "1")
      # Cancel
      cancel
      ;;
  esac
done


# serious flag
ask "pam_panic's behaviour" "Do you wish to destroy your LUKS header in case of emergency?\nThis means that your encrypted root device won't be readable anymore. After this question you will be asked to make a backup of this header."
serious=$?

if [ $serious -eq 0 ]; then
  serious_dev=$(getLUKSDevice UUID)
  if [ ! -z $serious_dev ]; then
    msg "pam_panic's behaviour" "We will destroy $(getLUKSDevice NAME) [$serious_dev] when you trigger the panic function."

    # LUKS header backup
    ask "LUKS Header backup" "Do you want to make a LUKS-Header backup now?\nIt will be saved at \"$LHBU\"."
    bu=$?
    case $bu in 
      "0")
        cryptsetup luksHeaderBackup $(getLUKSDevice NAME) --header-backup-file "$LHBU"
        msg "LUKS Header backup" "LUKSHeader backup has been saved here: $LHBU"
        ;;
    esac
  else
    msg "pam_panic's behaviour" "ERROR: There is no encrypted root device on /dev/sda."
    serious=1
  fi
fi


# poweroff / reboot behaviour
dialog --backtitle "pam_panic's Configuration Generator" \
  --title "pam_panic's behaviour" \
  --ok-label "Reboot" \
  --extra-button --extra-label "Shutdown" \
  --cancel-label "Nothing" \
  --yesno "Do you wish a reboot or a shutdown after issuing the panic function? n for nothing of those? " 10 80
power=$?


# Configuration generation
dialog --backtitle "pam_panic's Configuration Generator" \
  --infobox "Generating configuration..." 3 40
config="#%PAM-1.0\nauth       requisite    $SECUREDIR/pam_panic.so"

case $power in 
  "0")
    config="$config reboot"
    ;;
  "3")
    config="$config poweroff"
    ;;
esac

case $auth_mode in
  "3")
    config="$config password"
    ;;
  "0")
    config="$config allow=$auth_dev reject=$panic_dev"
    ;;
esac

case $serious in
  "0")
    config="$config serious=$serious_dev"
    ;;
esac
config="$config\naccount    requisite    $SECUREDIR/pam_panic.so"


# Write config file
writeout=0
if [ -f $CONFIGFILE ]; then
  ask "Configfile exist" "$CONFIGFILE exists. Overwrite it?"
  writeout=$?
  case $writeout in
    "0")
      echo -e "$config" > $CONFIGFILE
      ;;
  esac
else
  echo -e "$config" > $CONFIGFILE
fi


# Finished message
clear
[ $writeout -eq 0 ] && echo "Done! <3" || echo "Nothing done! </3"

echo -e "\n"
echo "What now?"
echo "========="
echo "Now we saved our configuration to $CONFIGFILE."
echo "If you want to let them apply to the other modules,"
echo "like in xscreensaver and system-local-login [the system login],"
echo "do as follows:"
echo -e "\t1. Open a module in /etc/pam.d/ (like xscreensaver or system-local-login).\n\t2. After the line \"#%PAM-1.0\" append\n\t\tauth       include    pampanic\n\t\taccount    include    pampanic\nAfter you have saved the file pam_panic will be working at once."
echo "If you got any question, don't hesitate to ask via IRC (chat.freenode.de in room #pampanic) or via mail."
echo -e "\nPress Enter to exit."
read -n1