authy-ssh

#!/usr/bin/env bash

VERSION="1.7"
AUTHY_URL="https://api.authy.com"
APP_ROOT=`dirname $0`
CONFIG_FILE="$APP_ROOT/authy-ssh.conf"
UPSTREAM_URL="https://raw.githubusercontent.com/authy/authy-ssh/master/authy-ssh"
READ_TIMEOUT=60
MIN_API_KEY_SIZE=12

OK=0
FAIL=1
SEQ="seq"

export TERM="xterm-256color"
NORMAL=$(tput sgr0)
GREEN=$(tput setaf 2; tput bold)
YELLOW=$(tput setaf 3)
RED=$(tput setaf 1)


function red() {
    echo -e "$RED$*$NORMAL"
}

function green() {
    echo -e "$GREEN$*$NORMAL"
}

function yellow() {
    echo -e "$YELLOW$*$NORMAL"
}

function debug() {
    if [[ $DEBUG_AUTHY ]]
    then
        echo ">>> $*"
    fi
}

function check_dependencies() {
  if ! type "seq" > /dev/null 2>&1;
  then
    if ! type "jot" > /dev/null 2>&1;
    then
      red "You need installed on your system either 'seq' or 'jot' command"
      exit $FAIL
    else
      SEQ="jot"
    fi
  fi
}

function escape_input() {
  sed "s/[;\`\"\$\' ]//g" <<<$*
}

function escape_number() {
  sed 's/[^0-9]*//g' <<< $*
}

function os_version() {
  echo `uname -srm`
}

function read_input() {
  read -t "$READ_TIMEOUT" input
  echo "$(escape_input $input)"
}

function read_number() {
  read -t "$READ_TIMEOUT" number
  echo "$(escape_number $number)"
}

function require_root() {
    debug "Checking if user is root"
    find_sshd_config
    if [[ ! -w $SSHD_CONFIG ]]
    then
      red "root permissions are required to run this command. try again using sudo"
      exit $FAIL
    fi
}

function require_curl() {
    which curl 2>&1 > /dev/null
    if [ $? -eq 0 ]
    then
      return $OK
    fi

    # if `which` is not installed this check is ran
    curl --help 2>&1 > /dev/null

    return $FAIL
}

function user_agent() {
  os="$(os_version)"
  echo "User-Agent: AuthySSH/${VERSION} (${os})"
}

function find_sshd_config() {
    debug "Trying to find sshd_config file"
    if [[ -f /etc/sshd_config ]]
    then
        SSHD_CONFIG="/etc/sshd_config"
    elif [[ -f /etc/ssh/sshd_config ]]
    then
        SSHD_CONFIG="/etc/ssh/sshd_config"
    else
        red "Cannot find sshd_config in your server. Authy SSH will be enabled when you add the ForceCommand to it"
    fi
}

function add_force_command() {
    debug "Trying to add force command to $SSHD_CONFIG"
    find_sshd_config
    authy_ssh_command="$1"

    if [[ -w $SSHD_CONFIG ]]
    then
      yellow "Adding 'ForceCommand ${authy_ssh_command} login' to ${SSHD_CONFIG}"
      uninstall_authy "quiet" # remove previous installations

      echo -e "\nForceCommand ${authy_ssh_command} login" >> ${SSHD_CONFIG}
      echo ""

      check_sshd_config_file

      red "    MAKE SURE YOU DO NOT MOVE/REMOVE ${authy_ssh_command} BEFORE UNINSTALLING AUTHY SSH"
      sleep 5
    fi
}

function check_sshd_config_file() {
  yellow "Checking the validity of $SSHD_CONFIG file..."

  sshd -t

  if [ $? -ne 0 ]
  then
    red "sshd_config file is invalid. MAKE SURE YOU DO NOT RESTART THE SSH SERVER UNTIL YOU FIX IT."
    exit $FAIL
  fi

}

function install_authy() {
    source="$1"
    dest="$2/authy-ssh"
    if [[ ! $2 ]]
    then
      dest="/usr/local/bin/authy-ssh" # defaults to /usr/local/bin
    fi
    config_file="${dest}.conf"

    #
    # Ensure our target directory is present
    #
    set -e
    mkdir -p `dirname "${dest}"`
    set +e

    if [[ ! -r `dirname "${dest}"` ]]
    then
      red "${dest} is not writable. Try again using sudo"
      return $FAIL
    fi

    yellow "Copying ${source} to ${dest}..."
    cp "${source}" "${dest}"

    yellow "Setting up permissions..."
    chmod 755 $dest

    if [[ ! -f ${config_file} ]]
    then
      echo -n "Enter the Authy API key: "
      read  authy_api_key

      if [ ${#authy_api_key} -lt ${MIN_API_KEY_SIZE} ]
      then
        red "you have entered a wrong API key"
        return $FAIL
      fi

      echo "Default action when api.authy.com cannot be contacted: "
      echo ""
      echo "  1. Disable two factor authentication until api.authy.com is back"
      echo "  2. Don't allow logins until api.authy.com is back"
      echo ""
      echo -n "type 1 or 2 to select the option: "
      read default_verify_action

      case $default_verify_action in
        1)
          default_verify_action="disable"
          ;;
        2)
          default_verify_action="enforce"
          ;;
        *)
          red "you have entered an invalid option"
          return $FAIL
          ;;
      esac

      yellow "Generating initial config on ${config_file}..."
      echo "banner=Good job! You've securely logged in with Authy." > "${config_file}"
      echo "api_key=${authy_api_key}" >> "${config_file}"
      echo "default_verify_action=${default_verify_action}" >> "${config_file}"
    else
      red "A config file was found on ${config_file}. Edit it manually if you want to change the API key"
    fi
    chmod 644 ${config_file}

    add_force_command "${dest}"

    echo ""
    echo "To enable two-factor authentication on your account type the following command: "
    echo ""

    if [[ $SUDO_USER ]]
    then
      green "   sudo ${dest} enable $SUDO_USER <your-email> <your-numeric-country-code> <your-cellphone>"
      green "   Example: sudo $0 enable $SUDO_USER myuser@example.com 1 401-390-9987"
    else
      green "   sudo ${dest} enable $USER <your-email> <your-numeric-country-code> <your-cellphone>"
      green "   Example: sudo $0 enable $USER myuser@example.com 1 401-390-9987"
    fi
    echo ""
    echo "To enable two-factor authentication on user account type: "
    echo ""
    green "   sudo ${dest} enable <local-username> <user-email> <user-cellphone-country-code> <user-cellphone>"
    echo ""
    echo "To uninstall Authy SSH type:"
    echo ""
    green "   sudo ${dest} uninstall"
    echo ""
    yellow "      Restart the SSH server to apply changes"
    echo ""
}

function uninstall_authy() {
    find_sshd_config

    if [[ $1 != "quiet" ]]
    then
      yellow "Uninstalling Authy SSH from $SSHD_CONFIG..."
    fi

    if [[ -w $SSHD_CONFIG ]]
    then
        sed -ie '/^ForceCommand.*authy-ssh.*/d' $SSHD_CONFIG
    fi

    if [[ $1 != "quiet" ]]
    then
        green "Authy SSH was uninstalled."
        yellow "Now restart the ssh server to apply changes and then remove ${APP_ROOT}/authy-ssh and $CONFIG_FILE"
    fi
}

function check_config_file() {
    debug "Checking config file at $CONFIG_FILE"
    dir=`dirname ${CONFIG_FILE}`
    if [[ ! -r $dir ]]
    then
        red "ERROR: ${dir} cannot be written by $USER"
        return $FAIL
    fi

    if [[ ! -f $CONFIG_FILE ]]
    then
        red "Authy ssh has not been configured" # FIXME: add more info
        return $FAIL
    fi

    if [[ $1 == "writable" && ! -w $CONFIG_FILE ]]
    then
        red "$CONFIG_FILE is not writable. Please try again using sudo"
        exit $FAIL
    fi

    chmod 644 "$CONFIG_FILE" 2>/dev/null
    return $OK
}

# Checks if the API KEY is valid. This function receives one argument which can be:
#   - run: runs a shell even if the test fails.
#   - anything else: exits the command
function check_api_key() {
    debug "Checking api key"
    if [ ${#AUTHY_API_KEY} -lt ${MIN_API_KEY_SIZE} ]
    then
        red "Cannot find a valid api key"
        run_shell
    fi

    return $OK
}

# Usage: $(read_config banner)
function read_config() {
    key="$1"

    if [[ -f $CONFIG_FILE ]]
    then
        KEYFOUND=$FAIL
        while IFS='=' read -r ckey value
        do
            if [[ $ckey == $key ]]
            then
                echo $value # don't stop the loop so we can read repeated keys
                KEYFOUND=$OK
            fi
        done < $CONFIG_FILE
        return $KEYFOUND
    fi

    red "ERROR: $config_file couldn't be found"
    return $FAIL
}

function protect_user() {
    local_user="$(escape_input "$1")"
    if [[ $local_user == "" ]]
    then
      local_user="$USER"
    fi

    eval home_path="~$local_user"
    auth_keys="${home_path}/.ssh/authorized_keys"
    debug "Protecting user: $local_user with auth keys: $auth_keys"

    if [[ ! -w $home_path ]]
    then
      red "You don't have access to $auth_keys. Please try again as root."
      exit $FAIL
    fi

    echo -n "Enter your public ssh key: "
    read ssh_key

    grep "$ssh_key" "$auth_keys" 2>&1 >/dev/null
    grep_exit_code=$?
    if [[ $grep_exit_code -eq 0 ]]
    then
      yellow "The ssh key is already present in $auth_keys. Please remove it and try again."
      exit $FAIL
    fi

    register_user_on_authy "$local_user"
    if [[ $? -ne 0 || ! $authy_user_id ]]
    then
      exit $FAIL
    fi

    echo "command=\"$COMMAND login $authy_user_id\" $ssh_key" >> "${auth_keys}"
    if [[ $(whoami) == "root" ]]
    then
      chown "$local_user" "$auth_keys"
    fi
    green "The user is now protected with authy"
}

# usage: register_user "local_user" "<email>" "<country-code>" "<cellphone>"
function register_user() {
  register_user_on_authy $*

  if [[ $? -ne 0 ]]
  then
      exit $FAIL
  fi

  if [[ $authy_user_id ]]
  then
      echo "user=$local_user:$authy_user_id" >> $CONFIG_FILE
      green "User was registered"
  else
      red "Cannot register user: $response"
  fi

}

function register_user_on_authy() {
    local_user="$(escape_input $1)"
    email="$(escape_input $2)"
    country_code="$(escape_number $3)"
    cellphone="$(escape_number $4)"

    if [[ $local_user == "" ]]
    then
      echo -n "Username: "
      local_user="$(read_input)"
    fi

    if [[ $country_code == "" ]]
    then
      echo -n "Your country code: "
      country_code="$(read_number)"
    fi

    if [[ $cellphone == "" ]]
    then
      echo -n "Your cellphone: "
      cellphone="$(read_number)"
    fi

    if [[ $email == "" ]]
    then
      echo -n "Your email: "
      email="$(read_input)"
    fi

    echo -e "

    Username:\t${local_user}
    Cellphone:\t(+${country_code}) ${cellphone}
    Email:\t${email}

"
    echo -n "Do you want to enable this user? (y/n) "
    read should_continue
    if [[ "$should_continue" != y* ]]
    then
      return $FAIL
    fi

    url="$AUTHY_URL/protected/json/users/new?api_key=${AUTHY_API_KEY}"

    response=`id "${local_user}" 2>/dev/null`
    if [[ $? -ne 0 ]]
    then
        red "$local_user was not found in your system"
        return $FAIL
    fi

    useragent="$(user_agent)"
    response=`curl --connect-timeout 10 "${url}" -A "${useragent}" -d user[email]="${email}" -d user[country_code]="${country_code}" -d user[cellphone]="${cellphone}" -s 2>/dev/null`
    ok=true

    debug "[register-user] url: $url | response: $response | curl exit stats: $?"

    if [[ $response == *cellphone* ]]
    then
        yellow "Cellphone is invalid"
        ok=false
    fi

    if [[ $response == *email* ]]
    then
        yellow "Email is invalid"
        ok=false
    fi

    if [[ $ok == false ]]
    then
        return $FAIL
    fi

    if [[ $response == *user*id* ]]
    then
      authy_user_id=`echo $response | grep -o '[0-9]\{1,\}'` # match the authy id
      return $OK
    elif [[ $response == "invalid key" ]]
    then
        yellow "The api_key value in $CONFIG_FILE is not valid"
    else
        red "Unknown response: $response"
    fi

    return $FAIL
}

function run_shell() {
    if [[ "$SSH_ORIGINAL_COMMAND" != "" ]] # when user runs: ssh server <command>
    then
        debug "running command: $SSH_ORIGINAL_COMMAND"
        exec /bin/bash -c "${SSH_ORIGINAL_COMMAND}"
    elif [ $SHELL ] # when user runs: ssh server
    then
        debug "running shell: $SHELL"
        exec -l $SHELL
    fi

    exit $?
}

function find_authy_id() {
    for user in `read_config user`
    do
        IFS=":"; declare -a authy_user=($user)
        if [[ ${authy_user[0]} == $USER ]]
        then
            echo $(escape_number ${authy_user[1]})
            return $OK
        fi
    done

    return $FAIL
}

# login <test|login> "token" "authy-id"
function login() {
    mode="$(escape_input $1)"
    authy_token="$(escape_number $2)"
    authy_id="$(escape_number $3)"

    if [[ $authy_id == "" ]]
    then
      authy_id="$(find_authy_id)"
    fi

    debug "Logging $authy_id with $authy_token in $mode mode."

    if [[ $authy_token == "" ]]
    then
      red "You have to enter only digits."
      return $FAIL
    fi

    size=${#authy_token}
    if [[ $size -lt 6 || $size -gt 10 ]]
    then
      red "You have to enter a valid token."
      return $FAIL
    fi

    useragent="$(user_agent)"
    url="$AUTHY_URL/protected/json/verify/${authy_token}/${authy_id}?api_key=${AUTHY_API_KEY}&force=true"

    response=`curl --connect-timeout 30 -sL -w "|%{http_code}" -A "${useragent}" "${url}"`
    curl_exit_code=$?
    IFS='|' response_body=($response) # convert to array

    debug "[verify-token] url: $url | response: $response | curl exit status: $curl_exit_code"

    if [ $curl_exit_code -ne 0 ] # something went wrong when running the command, let it pass
    then
        red "Error running curl"
    fi

    default_verify_action="$(read_config default_verify_action)"
    if [[ $default_verify_action == "disable" ]]
    then
        debug "Checking if authy service is up."
        check_response=`curl --connect-timeout 10 -s "${AUTHY_URL}" -A "${useragent}" -o /dev/null`
        check_exit_code=$?

        if [[ $check_exit_code == 7 || $check_exit_code == 28 ]]
        then
            red "Letting user pass through. api.authy.com could not be reached."
            run_shell
        fi
    fi

    if [[ "${response_body[1]}" == "200" ]] && [[ "${response_body[0]}" == *\"token\":\"is*valid\"* ]]
    then
        debug "Two-factor token was accepted."
        if [[ ! $AUTHY_TOKEN ]]
        then
            banner_text=$(read_config banner)
            if [[ $? == $OK ]];
            then
                green $banner_text
            fi
        fi

        if [[ $mode != "test" ]]
        then
            run_shell
        else
            debug "Test was successful"
            exit $OK
        fi
    else
        red "Invalid token. try again"
    fi

    return $FAIL # fail by default
}

function request_sms() {
    authy_id="$(escape_number $1)"
    url="$AUTHY_URL/protected/json/sms/${authy_id}?api_key=${AUTHY_API_KEY}&force=true"

    useragent="$(user_agent)"
    response=`curl --connect-timeout 10 -A "${useragent}" "${url}" 2>/dev/null`
    debug "[request sms] url: $url | response: $response | curl exit stats: $?"

    if [[ $response == *success*sent* ]]
    then
        green "SMS message was sent"
    elif [[ $response == *not*enabled* ]]
    then
        yellow "SMS is not enabled on Sandbox accounts. You need to upgrade to a Starter account at least."
    else
        red "Message couldn't be sent: $response"
    fi
}

# if this methods returns $OK the user is logged in.
function ask_token_and_log_user_in() {
    mode="$(escape_input $1)"
    authy_id="$(escape_number $2)"

    if [[ $authy_id == "" ]]
    then
      authy_id="$(find_authy_id)"
    fi

    if [[ $authy_id == "" && $mode == "test" ]] #user is not using authy, let it go
    then
      red "Cannot find authy id for $USER in $CONFIG_FILE"
      red "You have to enable it using 'authy-ssh enable'"
      exit $FAIL
    fi

    if [[ $authy_id == "" ]]
    then
      debug "User is not protected with authy."
      run_shell
    fi

    times=3
    if [[ $AUTHY_TOKEN ]] # env var
    then
      times=1
    fi

    for i in `$SEQ 1 $times`
    do
        authy_token="$(escape_number $AUTHY_TOKEN)"
        if [[ ! $AUTHY_TOKEN ]]
        then
          echo -n "Authy Token (type 'sms' to request a SMS token): "
          authy_token="$(read_input)"
        fi

        if [ $? -ne 0 ]
        then
            debug "Timeout on Authy Token read."
            exit $?
        fi

        case $authy_token in
            sms) request_sms "${authy_id}" ;;
            *)
              authy_token="$(escape_number $authy_token)"
              login "${mode}" "${authy_token}" "${authy_id}"
              ;;
        esac
    done

    return $FAIL
}

function update_authy() {
  temp_file="$(mktemp -t tmpXXXXXXXXX)"
  curl "${UPSTREAM_URL}" -o "$temp_file"
  chmod 755 "$temp_file"

  echo -n "Do you want to overwrite ${COMMAND} (y/n)? "
  read opt
  if [[ "$opt" == "y" ]]
  then
    mv "${temp_file}" "${COMMAND}"
    green "Now type authy-ssh test to verify everything is working."
  else
    rm "${temp_file}"
    yellow "Authy SSH was not updated."
  fi
}

require_curl

# get the absolute path to the command
cd `dirname $0`
COMMAND="$PWD/`basename $0`"
cd - >/dev/null

case $1 in
    install)
        check_dependencies
        install_authy "$0" "$2"
        ;;
    update)
        check_dependencies
        require_root
        update_authy
        ;;
    uninstall)
        require_root
        uninstall_authy
        ;;
    test|check)
        check_config_file
        check_dependencies
        AUTHY_API_KEY="$(read_config api_key)"
        check_api_key || exit
        ask_token_and_log_user_in "test"
        ;;
    enable|register)
        check_dependencies
        require_root
        check_config_file "writable"
        AUTHY_API_KEY="$(read_config api_key)"
        check_api_key
        register_user "$2" "$3" "$4" "$5"
        ;;
    login)
        check_config_file
        check_dependencies
        AUTHY_API_KEY="$(read_config api_key)"
        check_api_key
        ask_token_and_log_user_in "login" "$2"
        ;;
    protect)
        check_config_file
        check_dependencies
        AUTHY_API_KEY="$(read_config api_key)"
        protect_user "$2"
        ;;
    version)
        echo "Authy SSH v${VERSION}"
        exit 0
        ;;
    *)
        cat <<__EOF__
Usage: authy-ssh <command> <arguments>

VERSION $VERSION

Available commands:

    install
        installs Authy SSH in the given directory. This command needs sudo if the directory is not writable.

        sudo $0 install /usr/local/bin

    update
        updates Authy SSH using the main authy-ssh script:

        ${UPSTREAM_URL}

    uninstall
        uninstalls Authy SSH from sshd_config

        sudo $0 uninstall

    test
        tests if the Authy SSH is working correctly

    enable
        receives a list of arguments needed to register a user. usage:

        sudo $0 enable [local-user] [email] [numeric country code] [cellphone]

        Example: sudo $0 enable myuser myuser@example.com 1 401-390-9987

    protect
        installs authy-ssh for the given user

        $0 protect [user]

    login
        ask a token to the user if it is already registered.

    version
        prints the Authy SSH version

__EOF__
        ;;
esac