#!/bin/sh
# Boot from a local disk installation

CONFIG_BOOT_GUI_MENU_NAME='Heads Boot Menu'

. /etc/functions
. /etc/config

mount_boot()
{
  # Mount local disk if it is not already mounted
  if ! grep -q /boot /proc/mounts ; then
    mount -o ro /boot \
      || recovery "Unable to mount /boot"
  fi
}
verify_global_hashes()
{
  # Check the hashes of all the files, ignoring signatures for now
  check_config /boot force
  TMP_HASH_FILE="/tmp/kexec/kexec_hashes.txt"
  TMP_PACKAGE_TRIGGER_PRE="/tmp/kexec/kexec_package_trigger_pre.txt"
  TMP_PACKAGE_TRIGGER_POST="/tmp/kexec/kexec_package_trigger_post.txt"

  if cd /boot && sha256sum -c "$TMP_HASH_FILE" > /tmp/hash_output ; then
    return 0
  elif [ ! -f $TMP_HASH_FILE ]; then
    if (whiptail --clear --title 'ERROR: Missing Hash File!' \
      --yesno "The file containing hashes for /boot is missing!\n\nIf you are setting this system up for the first time, select Yes to update your list of checksums.\n\nOtherwise this could indicate a compromise and you should select No to return to the main menu.\n\nWould you like to update your checksums now?" 30 80) then
      update_checksums
    fi
    return 1
  else
    CHANGED_FILES=$(grep -v 'OK$' /tmp/hash_output | cut -f1 -d ':')

    # if files changed before package manager started, show stern warning
    if [ -f "$TMP_PACKAGE_TRIGGER_PRE" ]; then 
      PRE_CHANGED_FILES=$(grep '^CHANGED_FILES' $TMP_PACKAGE_TRIGGER_POST | cut -f 2 -d '=' | tr -d '"')
      TEXT="The OS logged that the following files failed the verification process BEFORE package updates ran:\n${PRE_CHANGED_FILES}\n\nCompare against the files Heads has detected have changed:\n${CHANGED_FILES}\n\nThis could indicate a compromise!\n\nWould you like to update your checksums anyway?"

    # if files changed after package manager started, probably caused by package manager
    elif [ -f "$TMP_PACKAGE_TRIGGER_POST" ]; then 
      LAST_PACKAGE_LIST=$(grep -E "^(Install|Remove|Upgrade|Reinstall):" $TMP_PACKAGE_TRIGGER_POST)
      UPDATE_INITRAMFS_PACKAGE=$(grep '^UPDATE_INITRAMFS_PACKAGE' $TMP_PACKAGE_TRIGGER_POST | cut -f 2 -d '=' | tr -d '"')

      if [ "$UPDATE_INITRAMFS_PACKAGE" != "" ]; then
        TEXT="The following files failed the verification process AFTER package updates ran:\n${CHANGED_FILES}\n\nThis is likely due to package triggers in$UPDATE_INITRAMFS_PACKAGE.\n\nYou will need to update your checksums for all files in /boot.\n\nWould you like to update your checksums now?"
      else
        TEXT="The following files failed the verification process AFTER package updates ran:\n${CHANGED_FILES}\n\nThis might be due to the following package updates:\n$LAST_PACKAGE_LIST.\n\nYou will need to update your checksums for all files in /boot.\n\nWould you like to update your checksums now?"
      fi

    else
      TEXT="The following files failed the verification process:\n${CHANGED_FILES}\n\nThis could indicate a compromise!\n\nWould you like to update your checksums now?"
    fi

    if (whiptail --clear --title 'ERROR: Boot Hash Mismatch' --yesno "$TEXT" 30 80) then
      update_checksums
    fi
    return 1
  fi
}
update_checksums()
{
  if (whiptail --title 'Update Checksums and sign all files in /boot' \
      --yesno "You have chosen to update the checksums and sign all of the files in /boot.\n\nThis means that you trust that the files in /boot have not been tampered with.\n\nYou will need your GPG key to continue and this change will modify your disk.\n\nDo you want to continue?" 16 80) then
    mount_boot
    mount -o rw,remount /boot

    cd /boot
    find ./ -type f ! -name '*kexec*' | xargs sha256sum > /boot/kexec_hashes.txt
    DEFAULT_FILES=$(cat /boot/kexec_default_hashes.txt | cut -f3 -d ' ')
    echo $DEFAULT_FILES | xargs sha256sum > /boot/kexec_default_hashes.txt

    # Remove any package trigger log files
    # We don't need them after the user decides to sign
    rm -f /boot/kexec_package_trigger*

    # sign and auto-roll config counter
    extparam=
    if [ "$CONFIG_TPM" = "y" ]; then
      extparam=-u
    fi
    kexec-sign-config -p /boot $extparam \
    || die "Failed to sign default config"

    # switch back to ro mode
    mount -o ro,remount /boot
  else
    echo "Returning to the main menu"
  fi
}

last_half=X
while true; do
  MAIN_MENU_OPTIONS=""
  unset totp_confirm
  # update the TOTP code every thirty seconds
  date=`date "+%Y-%m-%d %H:%M:%S"`
  seconds=`date "+%s"`
  half=`expr \( $seconds % 60 \) / 30`
  if [ "$CONFIG_TPM" = n ]; then
    TOTP="NO TPM"
  elif [ "$half" != "$last_half" ]; then
    last_half=$half;
    TOTP=`unseal-totp`
    if [ $? -ne 0 ]; then
      whiptail --clear --title "ERROR: TOTP Generation Failed!" \
        --menu "ERROR: Heads couldn't generate the TOTP code.\n\nIf you have just reflashed your BIOS, you will need to generate a new TOTP secret.\n\nIf you have not just reflashed your BIOS, THIS COULD INDICATE TAMPERING!\n\nIf this is the first time the system has booted, you should reset the TPM and set your own password\n\nHow would you like to proceed?" 30 80 4 \
        'g' ' Generate new TOTP secret' \
        'i' ' Ignore error and continue to default boot menu' \
        'p' ' Reset the TPM' \
        'x' ' Exit to recovery shell' \
        2>/tmp/whiptail || recovery "GUI menu failed"

      totp_confirm=$(cat /tmp/whiptail)
    fi
  fi

  if [ "$totp_confirm" = "i" -o -z "$totp_confirm" ]; then 
    whiptail --clear --title "$CONFIG_BOOT_GUI_MENU_NAME" \
      --menu "$date\nTOTP code: $TOTP" 20 80 10 \
      'y' ' Default boot' \
      'r' ' TOTP does not match, refresh code' \
      'n' ' TOTP does not match after refresh, troubleshoot' \
      'o' ' Other Boot Options -->' \
      'a' ' Advanced Settings -->' \
      'x' ' Exit to recovery shell' \
      2>/tmp/whiptail || recovery "GUI menu failed"

    totp_confirm=$(cat /tmp/whiptail)
  fi

  if [ "$totp_confirm" = "o" ]; then
    whiptail --clear --title "Other Boot Options" \
      --menu "Select A Boot Option" 20 80 10 \
      'm' ' Show OS boot menu' \
      'u' ' USB boot' \
      'i' ' Ignore tampering and force a boot (Unsafe!)' \
      'r' ' <-- Return to main menu' \
      2>/tmp/whiptail || recovery "GUI menu failed"

    totp_confirm=$(cat /tmp/whiptail)
  fi

  if [ "$totp_confirm" = "a" ]; then
    whiptail --clear --title "Advanced Settings" \
      --menu "Configure Advanced Settings" 20 80 10 \
      'g' ' Generate new TOTP secret' \
      'p' ' Reset the TPM' \
      's' ' Update checksums and sign all files in /boot' \
      'r' ' <-- Return to main menu' \
      2>/tmp/whiptail || recovery "GUI menu failed"

    totp_confirm=$(cat /tmp/whiptail)
  fi

  if [ "$totp_confirm" = "x" ]; then
    recovery "User requested recovery shell"
  fi

  if [ "$totp_confirm" = "r" ]; then
    continue
  fi

  if [ "$totp_confirm" = "n" ]; then
    if (whiptail --title "TOTP code mismatched" \
      --yesno "TOTP code mismatches could indicate either TPM tampering or clock drift:\n\nTo correct clock drift: 'date -s HH:MM:SS'\nand save it to the RTC: 'hwclock -w'\nthen reboot and try again.\n\nWould you like to exit to a recovery console?" 30 80) then
      echo ""
      echo "To correct clock drift: 'date -s HH:MM:SS'"
      echo "and save it to the RTC: 'hwclock -w'"
      echo "then reboot and try again"
      echo ""
      recovery "TOTP mismatch"
    else
      continue
    fi
  fi

  if [ "$totp_confirm" = "u" ]; then
    exec /bin/usb-init
    continue
  fi

  if [ "$totp_confirm" = "g" ]; then
    if (whiptail --title 'Generate new TOTP secret' \
        --yesno "This will erase your old secret and replace it with a new one!\n\nDo you want to proceed?" 16 80) then
      echo "Scan the QR code to add the new TOTP secret"
      /bin/seal-totp
      echo "Once you have scanned the QR code, hit Enter to reboot"
      read
      /bin/reboot
    else
      echo "Returning to the main menu"
    fi
    continue
  fi

  if [ "$totp_confirm" = "p" ]; then
    if (whiptail --title 'Reset the TPM' \
        --yesno "This will clear the TPM, erase the old TPM password and replace it with a new one!\n\nDo you want to proceed?" 16 80) then
      /bin/tpm-reset

      # now that the TPM is reset, remove invalid kexec_rollback.txt file
      mount_boot
      mount -o rw,remount /boot
      rm -f /boot/kexec_rollback.txt 
      mount -o ro,remount /boot

      echo "Scan the QR code to add the new TOTP secret"
      /bin/seal-totp
      echo "Once you have scanned the QR code, hit Enter to reboot"
      read
      /bin/reboot
    else
      echo "Returning to the main menu"
    fi
    continue
  fi

  if [ "$totp_confirm" = "m" ]; then
    # Try to select a kernel from the menu
    mount_boot
    verify_global_hashes
    if [ $? -ne 0 ]; then
      continue
    fi
    kexec-select-boot -m -b /boot -c "grub.cfg" -g
    continue
  fi

  if [ "$totp_confirm" = "i" ]; then
    # Run the menu selection in "force" mode, bypassing hash checks
    if (whiptail --title 'Unsafe Forced Boot Selected!' \
        --yesno "WARNING: You have chosen to skip all tamper checks and boot anyway.\n\nThis is an unsafe option!\n\nDo you want to proceed?" 16 80) then
      mount_boot
      kexec-select-boot -m -b /boot -c "grub.cfg" -g -f
    else
      echo "Returning to the main menu"
    fi
    continue
  fi

  if [ "$totp_confirm" = "s" ]; then
    update_checksums
    continue
  fi

  if [ "$totp_confirm" = "y" -o -n "$totp_confirm" ]; then
    # Try to boot the default
    mount_boot
    verify_global_hashes
    if [ $? -ne 0 ]; then
      continue
    fi
    DEFAULT_FILE=`find /boot/kexec_default.*.txt 2>/dev/null | head -1`
    if [ -r "$DEFAULT_FILE" ]; then
      kexec-select-boot -b /boot -c "grub.cfg" -g \
      || recovery "Failed default boot"
    else
      if (whiptail --title 'No Default Boot Option Configured' \
          --yesno "There is no default boot option configured yet. Would you like to load a menu of boot options? Otherwise you will return to the main menu." 16 80) then
        kexec-select-boot -m -b /boot -c "grub.cfg" -g
      else
        echo "Returning to the main menu"
      fi
      continue
    fi
  fi

done

recovery "Something failed during boot"