CSC/ECE 517 Fall 2023 - E2377. Reimplement impersonating users (functionality within impersonate controller.rb)

Expertiza

Expertiza is a Ruby on Rails based open source project. Instructors have the ability to add new projects, assignments, etc., as well as edit existing ones. Later on, they can view student submissions and grade them. Students can also use Expertiza to organize into teams to work on different projects and assignments and submit their work. They can also review other students' submissions.

Problem Statement

The current expertiza platform allows authorized users to impersonate others, utilizing session-based authentication. The challenge is to reimplement this feature in the new expertiza backend (https://github.com/expertiza/reimplementation-back-end), which employs JWT token authentication.

Key challenges include adapting the existing session-based logic to work seamlessly with JWT tokens and transitioning from a Model-View-Controller (MVC) architecture to an API-only setup, requiring responses in JSON format. The goal is to ensure the smooth integration of the impersonation feature into the new backend while addressing authentication changes and architectural shifts.

Solution

We plan to convert the impersonate users functionality from the MVC pattern in Expertiza to match the Rails API specification for the reimplementation backend repository. To do this we will reimplement the impersonate_controller.rb file located within expertiza/app/controllers/. The link to the original controller within expertizsa can be found at this link: Original Controller This is not the only file that we will be editing. We will be using JWT Tokens for authentication. The front end will still be responsible for storing the original user to get the original user back in function. Our code will work to change the current user as and when necessary in the API. Will also ensure that user privileges are checked to authorize only the relevant users to impersonate student users. Users that are super admin, TAs for other users or recursively parents of the user they are trying to impersonate can impersonate the user. We will also ensure that we have the supporting methods in the User class are implemented. One such example of a method that we may need to reimplement is “can_impersonate?” within the User class.

Design

UML Diagram

Methods Reimplemented

Original

def action_allowed?
    # Check for TA privileges first since TA's also have student privileges.
    if ['Student'].include? current_role_name
      !session[:super_user].nil?
    else
      ['Super-Administrator',
       'Administrator',
       'Instructor',
       'Teaching Assistant'].include? current_role_name
    end
  end

Updated -- we will remove the session and store the user with a JWT token to authenticate

Original

def auto_complete_for_user_name
    @users = session[:user].get_available_users(params[:user][:name])
    render inline: "<%= auto_complete_result @users, 'name' %>", layout: false
  end

Updated

--instead of using session we will just access the current user -- we will remove the inline rendering and return a JSON instead

Original

  def start
    flash[:error] = "This page doesn't take any query string." unless request.GET.empty?
  end

Updated --we will remove the flash error as it will not work in the new implementation

Original:

 def generate_session(user)
    AuthController.clear_user_info(session, nil)
    session[:original_user] = @original_user
    session[:impersonate] = true
    session[:user] = user
  end

Updated: -- We will not be using sessions so we will be using JWT tokens to authenticate users instead of making a traditional session

Original

def overwrite_session
    if params[:impersonate].nil?
      user = real_user(params[:user][:name])
      session[:super_user] = session[:user] if session[:super_user].nil?
      generate_session(user)
    elsif !params[:impersonate][:name].empty?
      user = real_user(params[:impersonate][:name])
      generate_session(user)
    else
      session[:user] = session[:super_user]
      session[:super_user] = nil
    end
  end

Updated --instead, we will just update the current User but we will authenticate the user with a JWT token instead.

Original

def check_if_input_is_valid
    if params[:user] && warn_for_special_chars(params[:user][:name], 'Username')
      flash[:error] = 'Please enter valid user name'
      redirect_back fallback_location: root_path
    elsif params[:impersonate] && warn_for_special_chars(params[:impersonate][:name], 'Username')
      flash[:error] = 'Please enter valid user name'
      redirect_back fallback_location: root_path
    end
  end

Updated: -- in this method we will remove the flash errors

Original

def check_if_user_impersonateable
    if params[:impersonate].nil?
      user = real_user(params[:user][:name])
      unless @original_user.can_impersonate? user
        @message = "You cannot impersonate '#{params[:user][:name]}'."
        temp
        AuthController.clear_user_info(session, nil)
      else
        overwrite_session
      end
    else
      unless params[:impersonate][:name].empty?
        overwrite_session
      end
    end
  end

Updated:

--we will change the session to a JWT token in this method

 Original 

def impersonate
    begin
      @original_user = session[:super_user] || session[:user]
      if params[:impersonate].nil?
        @message = "You cannot impersonate '#{params[:user][:name]}'."
        @message = 'User name cannot be empty' if params[:user][:name].empty?
        user = real_user(params[:user][:name])
        check_if_user_impersonateable if user
      elsif !params[:impersonate][:name].empty?
        # Impersonate a new account
        @message = "You cannot impersonate '#{params[:impersonate][:name]}'."
        user = real_user(params[:impersonate][:name])
        check_if_user_impersonateable if user
      # Revert to original account when currently in the impersonated session
      elsif !session[:super_user].nil?
        AuthController.clear_user_info(session, nil)
        session[:user] = session[:super_user]
        user = session[:user]
        session[:super_user] = nil
      end
      # Navigate to user's home location as the default landing page after impersonating or reverting
      AuthController.set_current_role(user.role_id, session)
      redirect_to action: AuthHelper.get_home_action(session[:user]),
                  controller: AuthHelper.get_home_controller(session[:user])
    rescue StandardError
      flash[:error] = @message
      redirect_back fallback_location: root_path
    end
  end

Updated: -- we will change the session to a JWT token and flash message from this method.

Original:

def real_user(name)
    if User.anonymized_view?(session[:ip])
      user = User.real_user_from_anonymized_name(name)
    else
      user = User.find_by(name: name)
    end
    return user
  end

Updated: -- we will implement a JWT token instead of using a session here

Original

def can_impersonate?(user)
    return true if role.super_admin?
    return true if teaching_assistant_for?(user)
    return true if recursively_parent_of(user)

    false
  end

-- We will reimplement these methods to work with our JWT based authentication system

Original

def recursively_parent_of(user)
    p = user.parent
    return false if p.nil?
    return true if p == self
    return false if p.role.super_admin?

    recursively_parent_of(p)
  end

-- We will reimplement these methods to work with our JWT based authentication system

Original

def teaching_assistant_for?(student)
    return false unless teaching_assistant?
    return false unless student.role.name == 'Student'

    # We have to use the Ta object instead of User object
    # because single table inheritance is not currently functioning
    ta = Ta.find(id)
    return true if ta.courses_assisted_with.any? do |c|
      c.assignments.map(&:participants).flatten.map(&:user_id).include? student.id
    end
  end

-- We will reimplement these methods to work with our JWT based authentication system

Test Plan

For the testing of this project, we will first test all functionality using the Postman API. If everything works as expected, we will then start testing our program using the RSwag tool. This will allow us to test and explore operations using a UI and directly from the rspec integration tests.
The video links for these testing methods will be posted here when we complete it.

Team

Mentor
Renji Joseph Sabu <rsabu@ncsu.edu>

Students
Manoj Ayyappan <mayyapp@ncsu.edu>
Pradeep Patil <papatil@ncsu.edu>
Maya Patel <mdpatel2@ncsu.edu>

Pull Request

Changes for this project are under Expertiza Pull Request