testsAndMisc/linux_configuration/scripts/utils/setup_passwordless_system.sh

#!/bin/bash
# Script to set up passwordless sudo and automatic login
# Configures lightdm for auto-login and sudo for passwordless access
# Handles sudo privileges automatically
# Usage: ./setup_passwordless_system.sh [--reboot] [--logout]
#   --reboot: Offer to reboot after setup completion
#   --logout: Allow restart of LightDM (which will logout the user)

set -e # Exit on any error

# Check for flags
OFFER_REBOOT=false
ALLOW_LOGOUT=false
for arg in "$@"; do
  case $arg in
    --reboot)
      OFFER_REBOOT=true
      shift
      ;;
    --logout)
      ALLOW_LOGOUT=true
      shift
      ;;
    *)
      # Unknown option, keep it for sudo check
      ;;
  esac
done

# Function to check and request sudo privileges
check_sudo() {
  if [[ $EUID -ne 0 ]]; then
    echo "This script requires sudo privileges to modify system configurations."
    echo "Requesting sudo access..."
    exec sudo "$0" "$@"
  fi
}

# Check for sudo privileges first
check_sudo "$@"

echo "Passwordless System Setup"
echo "========================"
echo "Current Date: $(date)"
echo "User: $USER"
echo "Original user: ${SUDO_USER:-$USER}"

# Verify we have a valid user
if [[ -z ${SUDO_USER} ]]; then
  echo "Error: Could not determine the original user. Please run this script with sudo."
  exit 1
fi

TARGET_USER="${SUDO_USER}"
echo "Target user for configuration: $TARGET_USER"

# Function to backup files
backup_file() {
  local file="$1"
  if [[ -f $file ]]; then
    local backup timestamp
    timestamp=$(date +%Y%m%d_%H%M%S)
    backup="${file}.backup.$timestamp"
    cp "$file" "$backup"
    echo "✓ Backed up $file to $backup"
  fi
}

# Function to configure passwordless sudo
configure_passwordless_sudo() {
  echo ""
  echo "1. Configuring Passwordless Sudo..."
  echo "=================================="

  local sudoers_file="/etc/sudoers.d/99-passwordless-${TARGET_USER}"

  # Create sudoers configuration for passwordless access
  cat > "$sudoers_file" << EOF
# Passwordless sudo configuration for user: ${TARGET_USER}
# Created by setup_passwordless_system.sh on $(date)
# WARNING: This allows the user to run any command without password

# Allow user to run all commands without password
${TARGET_USER} ALL=(ALL) NOPASSWD: ALL

# Ensure user can run sudo without TTY (useful for scripts)
Defaults:${TARGET_USER} !requiretty

# Keep environment variables for user convenience
Defaults:${TARGET_USER} env_keep += "HOME PATH DISPLAY XAUTHORITY"
EOF

  # Set proper permissions for sudoers file
  chmod 440 "$sudoers_file"

  # Verify the sudoers file syntax
  if visudo -c -f "$sudoers_file"; then
    echo "✓ Passwordless sudo configured for user: $TARGET_USER"
    echo "✓ Sudoers file created: $sudoers_file"
  else
    echo "✗ Error: Invalid sudoers syntax. Removing file for safety."
    rm -f "$sudoers_file"
    exit 1
  fi
}

# Function to configure lightdm auto-login
configure_lightdm_autologin() {
  echo ""
  echo "2. Configuring LightDM Auto-Login..."
  echo "==================================="

  local lightdm_conf="/etc/lightdm/lightdm.conf"
  local lightdm_conf_dir="/etc/lightdm/lightdm.conf.d"
  local custom_conf="$lightdm_conf_dir/50-autologin.conf"

  # Create lightdm config directory if it doesn't exist
  mkdir -p "$lightdm_conf_dir"

  # Backup existing lightdm configuration
  backup_file "$lightdm_conf"

  # Check if lightdm is installed
  if ! command -v lightdm &> /dev/null; then
    echo "Warning: LightDM not found. Installing lightdm..."
    pacman -S --noconfirm lightdm lightdm-gtk-greeter
  fi

  # Method 1: Update the main lightdm.conf file directly
  sed -i "/^#autologin-user=/c\autologin-user=${TARGET_USER}" "$lightdm_conf"
  sed -i "/^#autologin-user-timeout=/c\autologin-user-timeout=0" "$lightdm_conf"
  sed -i "/^#autologin-session=/c\autologin-session=i3" "$lightdm_conf"
  sed -i "/^#autologin-in-background=/c\autologin-in-background=false" "$lightdm_conf"

  # Also set user-session to i3 as fallback
  sed -i "/^#user-session=/c\user-session=i3" "$lightdm_conf"

  echo "✓ LightDM auto-login configured in main config file"

  # Method 2: Also create the separate config file for redundancy
  cat > "$custom_conf" << EOF
# LightDM Auto-Login Configuration
# Created by setup_passwordless_system.sh on $(date)

[Seat:*]
# Enable auto-login
autologin-user=${TARGET_USER}
autologin-user-timeout=0
autologin-session=i3

# Disable user switching and guest account
allow-user-switching=false
allow-guest=false

# Set session defaults
user-session=i3
greeter-session=lightdm-gtk-greeter

# Disable screen lock timeout during login
autologin-in-background=false
EOF

  echo "✓ LightDM auto-login also configured in separate config file: $custom_conf"

  # Enable lightdm service
  systemctl enable lightdm.service
  echo "✓ LightDM service enabled"

  # Restart lightdm to apply changes only if --logout flag is provided
  if [[ $ALLOW_LOGOUT == true ]]; then
    echo "Restarting LightDM to apply auto-login settings..."
    systemctl restart lightdm.service
    echo "✓ LightDM restarted"
  else
    echo "✓ LightDM configuration complete (restart lightdm or reboot to activate auto-login)"
  fi
}

# Function to configure i3 session
configure_i3_session() {
  echo ""
  echo "3. Configuring i3 Session..."
  echo "==========================="

  local xsessions_dir="/usr/share/xsessions"
  local i3_desktop="$xsessions_dir/i3.desktop"

  # Create xsessions directory if it doesn't exist
  mkdir -p "$xsessions_dir"

  # Check if i3.desktop exists, create if not
  if [[ ! -f $i3_desktop ]]; then
    cat > "$i3_desktop" << EOF
[Desktop Entry]
Name=i3
Comment=improved dynamic tiling window manager
Exec=i3
TryExec=i3
Type=Application
X-LightDM-DesktopName=i3
DesktopNames=i3
Keywords=tiling;wm;windowmanager;window;manager;
EOF
    echo "✓ Created i3 desktop session file: $i3_desktop"
  else
    echo "✓ i3 desktop session file already exists"
  fi

  # Ensure user has i3 config directory
  local user_home="/home/${TARGET_USER}"
  local i3_config_dir="$user_home/.config/i3"

  if [[ ! -d $i3_config_dir ]]; then
    sudo -u "$TARGET_USER" mkdir -p "$i3_config_dir"
    echo "✓ Created i3 config directory for user: $TARGET_USER"
  fi
}

# Function to configure additional auto-login settings
configure_additional_settings() {
  echo ""
  echo "4. Configuring Additional Settings..."
  echo "===================================="

  # Add user to autologin group if it exists
  if getent group autologin &> /dev/null; then
    usermod -a -G autologin "$TARGET_USER"
    echo "✓ Added $TARGET_USER to autologin group"
  else
    # Create autologin group
    groupadd -r autologin
    usermod -a -G autologin "$TARGET_USER"
    echo "✓ Created autologin group and added $TARGET_USER"
  fi

  # Configure pam for auto-login (if needed)
  local pam_lightdm="/etc/pam.d/lightdm-autologin"
  if [[ ! -f $pam_lightdm ]]; then
    cat > "$pam_lightdm" << EOF
#%PAM-1.0
# LightDM auto-login PAM configuration
# Created by setup_passwordless_system.sh on $(date)

auth        required    pam_unix.so nullok
auth        optional    pam_permit.so
auth        optional    pam_gnome_keyring.so
account     include     system-local-login
password    include     system-local-login
session     include     system-local-login
session     optional    pam_gnome_keyring.so auto_start
EOF
    echo "✓ Created PAM configuration for auto-login"
  fi
}

# Function to test configurations
test_configurations() {
  echo ""
  echo "5. Testing Configurations..."
  echo "==========================="

  # Test sudo configuration
  echo "Testing passwordless sudo..."
  if sudo -u "$TARGET_USER" sudo -n true 2> /dev/null; then
    echo "✓ Passwordless sudo test passed"
  else
    echo "! Passwordless sudo test failed (may require logout/login)"
  fi

  # Test lightdm configuration
  echo "Testing LightDM configuration..."
  if lightdm --test-mode --debug 2> /dev/null | grep -q "seat"; then
    echo "✓ LightDM configuration test passed"
  else
    echo "! LightDM configuration test completed (check logs if issues occur)"
  fi

  # Verify user is in autologin group
  if groups "$TARGET_USER" | grep -q autologin; then
    echo "✓ User is in autologin group"
  else
    echo "! User may not be in autologin group"
  fi
}

# Function to show security warnings
show_security_warnings() {
  echo ""
  echo "⚠️  SECURITY WARNINGS ⚠️"
  echo "========================"
  echo ""
  echo "The following security changes have been made:"
  echo ""
  echo "1. PASSWORDLESS SUDO:"
  echo "   • User '$TARGET_USER' can now run ANY command as root without password"
  echo "   • This includes system-critical operations and file modifications"
  echo "   • Malicious software running as this user can gain full system access"
  echo ""
  echo "2. AUTO-LOGIN:"
  echo "   • System automatically logs in user '$TARGET_USER' on boot"
  echo "   • No password required to access the desktop environment"
  echo "   • Physical access to the machine = full user access"
  echo ""
  echo "3. RECOMMENDATIONS:"
  echo "   • Use full disk encryption to protect against physical access"
  echo "   • Ensure the system is in a physically secure location"
  echo "   • Consider using this only on personal/development machines"
  echo "   • Regularly monitor system logs for unauthorized access"
  echo "   • Keep the system updated and use a firewall"
  echo ""
  echo "4. TO DISABLE THESE SETTINGS:"
  echo "   • Remove passwordless sudo: sudo rm /etc/sudoers.d/99-passwordless-${TARGET_USER}"
  echo "   • Disable auto-login: sudo rm /etc/lightdm/lightdm.conf.d/50-autologin.conf"
  echo "   • Restart LightDM: sudo systemctl restart lightdm"
  echo ""
}

# Function to show final instructions
show_final_instructions() {
  echo ""
  echo "=========================================="
  echo "Passwordless System Setup Complete"
  echo "=========================================="
  echo "Summary:"
  echo "✓ Passwordless sudo configured for user: $TARGET_USER"
  echo "✓ LightDM auto-login configured"
  echo "✓ i3 session configured"
  echo "✓ Additional auto-login settings applied"
  echo ""
  echo "Changes will take effect after:"
  echo "• Logout/login for sudo changes"
  echo "• System reboot for auto-login"
  echo ""
  echo "To verify after reboot:"
  echo "  sudo whoami  # Should not ask for password"
  echo "  systemctl status lightdm  # Should show auto-login active"
  echo ""
  echo "Configuration files created:"
  echo "  /etc/sudoers.d/99-passwordless-${TARGET_USER}"
  echo "  /etc/lightdm/lightdm.conf.d/50-autologin.conf"
  echo "  /etc/pam.d/lightdm-autologin"
  echo ""
  echo "IMPORTANT: Reboot recommended to activate all changes!"
}

# Main execution
configure_passwordless_sudo
configure_lightdm_autologin
configure_i3_session
configure_additional_settings
test_configurations
show_security_warnings
show_final_instructions

# Only offer reboot if --reboot flag was provided
if [[ $OFFER_REBOOT == true ]]; then
  echo ""
  echo "Would you like to reboot now to activate all changes?"
  read -p "Reboot system now? (y/N): " -n 1 -r
  echo

  if [[ $REPLY =~ ^[Yy]$ ]]; then
    echo "Rebooting system in 5 seconds..."
    sleep 5
    reboot
  else
    echo "Remember to reboot when convenient to activate all changes."
  fi
else
  echo ""
  echo "Setup completed successfully."
  echo "Remember to reboot when convenient to activate all changes."
  echo "To automatically prompt for reboot in the future, use: $0 --reboot"
fi