Add WebAuthn as an alternative 2FA method (mastodon#14466)

* feat: add possibility of adding WebAuthn security keys to use as 2FA This adds a basic UI for enabling WebAuthn 2FA. We did a little refactor to the Settings page for editing the 2FA methods – now it will list the methods that are available to the user (TOTP and WebAuthn) and from there they'll be able to add or remove any of them. Also, it's worth mentioning that for enabling WebAuthn it's required to have TOTP enabled, so the first time that you go to the 2FA Settings page, you'll be asked to set it up. This work was inspired by the one donde by Github in their platform, and despite it could be approached in different ways, we decided to go with this one given that we feel that this gives a great UX. Co-authored-by: Facundo Padula <[email protected]> * feat: add request for WebAuthn as second factor at login if enabled This commits adds the feature for using WebAuthn as a second factor for login when enabled. If users have WebAuthn enabled, now a page requesting for the use of a WebAuthn credential for log in will appear, although a link redirecting to the old page for logging in using a two-factor code will also be present. Co-authored-by: Facundo Padula <[email protected]> * feat: add possibility of deleting WebAuthn Credentials Co-authored-by: Facundo Padula <[email protected]> * feat: disable WebAuthn when an Admin disables 2FA for a user Co-authored-by: Facundo Padula <[email protected]> * feat: remove ability to disable TOTP leaving only WebAuthn as 2FA Following examples form other platforms like Github, we decided to make Webauthn 2FA secondary to 2FA with TOTP, so that we removed the possibility of removing TOTP authentication only, leaving users with just WEbAuthn as 2FA. Instead, users will have to click on 'Disable 2FA' in order to remove second factor auth. The reason for WebAuthn being secondary to TOPT is that in that way, users will still be able to log in using their code from their phone's application if they don't have their security keys with them – or maybe even lost them. * We had to change a little the flow for setting up TOTP, given that now it's possible to setting up again if you already had TOTP, in order to let users modify their authenticator app – given that now it's not possible for them to disable TOTP and set it up again with another authenticator app. So, basically, now instead of storing the new `otp_secret` in the user, we store it in the session until the process of set up is finished. This was because, as it was before, when users clicked on 'Edit' in the new two-factor methods lists page, but then went back without finishing the flow, their `otp_secret` had been changed therefore invalidating their previous authenticator app, making them unable to log in again using TOTP. Co-authored-by: Facundo Padula <[email protected]> * refactor: fix eslint errors The PR build was failing given that linting returning some errors. This commit attempts to fix them. * refactor: normalize i18n translations The build was failing given that i18n translations files were not normalized. This commits fixes that. * refactor: avoid having the webauthn gem locked to a specific version * refactor: use symbols for routes without '/' * refactor: avoid sending webauthn disabled email when 2FA is disabled When an admins disable 2FA for users, we were sending two mails to them, one notifying that 2FA was disabled and the other to notify that WebAuthn was disabled. As the second one is redundant since the first email includes it, we can remove it and send just one email to users. * refactor: avoid creating new env variable for webauthn_origin config * refactor: improve flash error messages for webauthn pages Co-authored-by: Facundo Padula <[email protected]>
hachyderm · Aug 24, 2020 · e8d41bc · e8d41bc
1 parent a3ec9af
commit e8d41bc
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diff --git a/Gemfile b/Gemfile
@@ -99,6 +99,7 @@ gem 'twitter-text', '~> 1.14'
 gem 'tzinfo-data', '~> 1.2020'
 gem 'webpacker', '~> 5.2'
 gem 'webpush'
+gem 'webauthn', '~> 3.0.0.alpha1'
 
 gem 'json-ld'
 gem 'json-ld-preloaded', '~> 3.1'

diff --git a/Gemfile.lock b/Gemfile.lock
@@ -67,6 +67,7 @@ GEM
       public_suffix (>= 2.0.2, < 5.0)
     airbrussh (1.4.0)
       sshkit (>= 1.6.1, != 1.7.0)
+    android_key_attestation (0.3.0)
     annotate (3.1.1)
       activerecord (>= 3.2, < 7.0)
       rake (>= 10.4, < 14.0)
@@ -76,6 +77,7 @@ GEM
       encryptor (~> 3.0.0)
     av (0.9.0)
       cocaine (~> 0.5.3)
+    awrence (1.1.1)
     aws-eventstream (1.1.0)
     aws-partitions (1.356.0)
     aws-sdk-core (3.104.3)
@@ -97,6 +99,7 @@ GEM
       coderay (>= 1.0.0)
       erubi (>= 1.0.0)
       rack (>= 0.9.0)
+    bindata (2.4.8)
     binding_of_caller (0.8.0)
       debug_inspector (>= 0.0.1)
     blurhash (0.1.4)
@@ -138,6 +141,7 @@ GEM
       xpath (~> 3.2)
     case_transform (0.2)
       activesupport
+    cbor (0.5.9.6)
     charlock_holmes (0.7.7)
     chewy (5.1.0)
       activesupport (>= 4.0)
@@ -153,6 +157,9 @@ GEM
     color_diff (0.1)
     concurrent-ruby (1.1.7)
     connection_pool (2.2.3)
+    cose (1.0.0)
+      cbor (~> 0.5.9)
+      openssl-signature_algorithm (~> 0.4.0)
     crack (0.4.3)
       safe_yaml (~> 1.0.0)
     crass (1.0.6)
@@ -377,6 +384,8 @@ GEM
     omniauth-saml (1.10.2)
       omniauth (~> 1.3, >= 1.3.2)
       ruby-saml (~> 1.9)
+    openssl (2.2.0)
+    openssl-signature_algorithm (0.4.0)
     orm_adapter (0.5.0)
     ox (2.13.2)
     paperclip (6.0.0)
@@ -547,10 +556,13 @@ GEM
     rufus-scheduler (3.6.0)
       fugit (~> 1.1, >= 1.1.6)
     safe_yaml (1.0.5)
+    safety_net_attestation (0.4.0)
+      jwt (~> 2.0)
     sanitize (5.2.1)
       crass (~> 1.0.2)
       nokogiri (>= 1.8.0)
       nokogumbo (~> 2.0)
+    securecompare (1.0.0)
     semantic_range (2.3.0)
     sidekiq (6.1.1)
       connection_pool (>= 2.2.2)
@@ -605,6 +617,9 @@ GEM
     thwait (0.2.0)
       e2mmap
     tilt (2.0.10)
+    tpm-key_attestation (0.9.0)
+      bindata (~> 2.4)
+      openssl-signature_algorithm (~> 0.4.0)
     tty-color (0.5.2)
     tty-cursor (0.7.1)
     tty-prompt (0.22.0)
@@ -628,6 +643,16 @@ GEM
     uniform_notifier (1.13.0)
     warden (1.2.8)
       rack (>= 2.0.6)
+    webauthn (3.0.0.alpha1)
+      android_key_attestation (~> 0.3.0)
+      awrence (~> 1.1)
+      bindata (~> 2.4)
+      cbor (~> 0.5.9)
+      cose (~> 1.0)
+      openssl (~> 2.0)
+      safety_net_attestation (~> 0.4.0)
+      securecompare (~> 1.0)
+      tpm-key_attestation (~> 0.9.0)
     webmock (3.8.3)
       addressable (>= 2.3.6)
       crack (>= 0.3.2)
@@ -775,6 +800,7 @@ DEPENDENCIES
   tty-prompt (~> 0.22)
   twitter-text (~> 1.14)
   tzinfo-data (~> 1.2020)
+  webauthn (~> 3.0.0.alpha1)
   webmock (~> 3.8)
   webpacker (~> 5.2)
   webpush
diff --git a/app/controllers/auth/sessions_controller.rb b/app/controllers/auth/sessions_controller.rb
@@ -37,6 +37,22 @@ def destroy
     store_location_for(:user, tmp_stored_location) if continue_after?
   end
 
+  def webauthn_options
+    user = find_user
+
+    if user.webauthn_enabled?
+      options_for_get = WebAuthn::Credential.options_for_get(
+        allow: user.webauthn_credentials.pluck(:external_id)
+      )
+
+      session[:webauthn_challenge] = options_for_get.challenge
+
+      render json: options_for_get, status: :ok
+    else
+      render json: { error: t('webauthn_credentials.not_enabled') }, status: :unauthorized
+    end
+  end
+
   protected
 
   def find_user
@@ -51,7 +67,7 @@ def find_user
   end
 
   def user_params
-    params.require(:user).permit(:email, :password, :otp_attempt, :sign_in_token_attempt)
+    params.require(:user).permit(:email, :password, :otp_attempt, :sign_in_token_attempt, credential: {})
   end
 
   def after_sign_in_path_for(resource)

diff --git a/app/controllers/concerns/two_factor_authentication_concern.rb b/app/controllers/concerns/two_factor_authentication_concern.rb
@@ -8,7 +8,23 @@ module TwoFactorAuthenticationConcern
   end
 
   def two_factor_enabled?
-    find_user&.otp_required_for_login?
+    find_user&.two_factor_enabled?
+  end
+
+  def valid_webauthn_credential?(user, webauthn_credential)
+    user_credential = user.webauthn_credentials.find_by!(external_id: webauthn_credential.id)
+
+    begin
+      webauthn_credential.verify(
+        session[:webauthn_challenge],
+        public_key: user_credential.public_key,
+        sign_count: user_credential.sign_count
+      )
+
+      user_credential.update!(sign_count: webauthn_credential.sign_count)
+    rescue WebAuthn::Error
+      false
+    end
   end
 
   def valid_otp_attempt?(user)
@@ -21,14 +37,29 @@ def valid_otp_attempt?(user)
   def authenticate_with_two_factor
     user = self.resource = find_user
 
-    if user_params[:otp_attempt].present? && session[:attempt_user_id]
-      authenticate_with_two_factor_attempt(user)
+    if user.webauthn_enabled? && user_params[:credential].present? && session[:attempt_user_id]
+      authenticate_with_two_factor_via_webauthn(user)
+    elsif user_params[:otp_attempt].present? && session[:attempt_user_id]
+      authenticate_with_two_factor_via_otp(user)
     elsif user.present? && user.external_or_valid_password?(user_params[:password])
       prompt_for_two_factor(user)
     end
   end
 
-  def authenticate_with_two_factor_attempt(user)
+  def authenticate_with_two_factor_via_webauthn(user)
+    webauthn_credential = WebAuthn::Credential.from_get(user_params[:credential])
+
+    if valid_webauthn_credential?(user, webauthn_credential)
+      session.delete(:attempt_user_id)
+      remember_me(user)
+      sign_in(user)
+      render json: { redirect_path: root_path }, status: :ok
+    else
+      render json: { error: t('webauthn_credentials.invalid_credential') }, status: :unprocessable_entity
+    end
+  end
+
+  def authenticate_with_two_factor_via_otp(user)
     if valid_otp_attempt?(user)
       session.delete(:attempt_user_id)
       remember_me(user)
@@ -43,6 +74,12 @@ def prompt_for_two_factor(user)
     set_locale do
       session[:attempt_user_id] = user.id
       @body_classes = 'lighter'
+      @webauthn_enabled = user.webauthn_enabled?
+      @scheme_type = if user.webauthn_enabled? && user_params[:otp_attempt].blank?
+                       'webauthn'
+                     else
+                       'totp'
+                     end
       render :two_factor
     end
   end

diff --git a/app/controllers/settings/two_factor_authentication/confirmations_controller.rb b/app/controllers/settings/two_factor_authentication/confirmations_controller.rb
@@ -18,18 +18,21 @@ def new
       end
 
       def create
-        if current_user.validate_and_consume_otp!(confirmation_params[:otp_attempt])
+        if current_user.validate_and_consume_otp!(confirmation_params[:otp_attempt], otp_secret: session[:new_otp_secret])
           flash.now[:notice] = I18n.t('two_factor_authentication.enabled_success')
 
           current_user.otp_required_for_login = true
+          current_user.otp_secret = session[:new_otp_secret]
           @recovery_codes = current_user.generate_otp_backup_codes!
           current_user.save!
 
           UserMailer.two_factor_enabled(current_user).deliver_later!
 
+          session.delete(:new_otp_secret)
+
           render 'settings/two_factor_authentication/recovery_codes/index'
         else
-          flash.now[:alert] = I18n.t('two_factor_authentication.wrong_code')
+          flash.now[:alert] = I18n.t('otp_authentication.wrong_code')
           prepare_two_factor_form
           render :new
         end
@@ -43,12 +46,15 @@ def confirmation_params
 
       def prepare_two_factor_form
         @confirmation = Form::TwoFactorConfirmation.new
-        @provision_url = current_user.otp_provisioning_uri(current_user.email, issuer: Rails.configuration.x.local_domain)
+        @new_otp_secret = session[:new_otp_secret]
+        @provision_url = current_user.otp_provisioning_uri(current_user.email,
+                                                           otp_secret: @new_otp_secret,
+                                                           issuer: Rails.configuration.x.local_domain)
         @qrcode = RQRCode::QRCode.new(@provision_url)
       end
 
       def ensure_otp_secret
-        redirect_to settings_two_factor_authentication_path unless current_user.otp_secret
+        redirect_to settings_otp_authentication_path if session[:new_otp_secret].blank?
       end
     end
   end

diff --git a/app/controllers/settings/two_factor_authentication/otp_authentication_controller.rb b/app/controllers/settings/two_factor_authentication/otp_authentication_controller.rb
@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+module Settings
+  module TwoFactorAuthentication
+    class OtpAuthenticationController < BaseController
+      include ChallengableConcern
+
+      layout 'admin'
+
+      before_action :authenticate_user!
+      before_action :verify_otp_not_enabled, only: [:show]
+      before_action :require_challenge!, only: [:create]
+
+      skip_before_action :require_functional!
+
+      def show
+        @confirmation = Form::TwoFactorConfirmation.new
+      end
+
+      def create
+        session[:new_otp_secret] = User.generate_otp_secret(32)
+
+        redirect_to new_settings_two_factor_authentication_confirmation_path
+      end
+
+      private
+
+      def confirmation_params
+        params.require(:form_two_factor_confirmation).permit(:otp_attempt)
+      end
+
+      def verify_otp_not_enabled
+        redirect_to settings_two_factor_authentication_methods_path if current_user.otp_enabled?
+      end
+
+      def acceptable_code?
+        current_user.validate_and_consume_otp!(confirmation_params[:otp_attempt]) ||
+          current_user.invalidate_otp_backup_code!(confirmation_params[:otp_attempt])
+      end
+    end
+  end
+end
diff --git a/app/controllers/settings/two_factor_authentication/webauthn_credentials_controller.rb b/app/controllers/settings/two_factor_authentication/webauthn_credentials_controller.rb
@@ -0,0 +1,103 @@
+# frozen_string_literal: true
+
+module Settings
+  module TwoFactorAuthentication
+    class WebauthnCredentialsController < BaseController
+      layout 'admin'
+
+      before_action :authenticate_user!
+      before_action :require_otp_enabled
+      before_action :require_webauthn_enabled, only: [:index, :destroy]
+
+      def new; end
+
+      def index; end
+
+      def options
+        current_user.update(webauthn_id: WebAuthn.generate_user_id) unless current_user.webauthn_id
+
+        options_for_create = WebAuthn::Credential.options_for_create(
+          user: {
+            name: current_user.account.username,
+            display_name: current_user.account.username,
+            id: current_user.webauthn_id,
+          },
+          exclude: current_user.webauthn_credentials.pluck(:external_id)
+        )
+
+        session[:webauthn_challenge] = options_for_create.challenge
+
+        render json: options_for_create, status: :ok
+      end
+
+      def create
+        webauthn_credential = WebAuthn::Credential.from_create(params[:credential])
+
+        if webauthn_credential.verify(session[:webauthn_challenge])
+          user_credential = current_user.webauthn_credentials.build(
+            external_id: webauthn_credential.id,
+            public_key: webauthn_credential.public_key,
+            nickname: params[:nickname],
+            sign_count: webauthn_credential.sign_count
+          )
+
+          if user_credential.save
+            flash[:success] = I18n.t('webauthn_credentials.create.success')
+            status = :ok
+
+            if current_user.webauthn_credentials.size == 1
+              UserMailer.webauthn_enabled(current_user).deliver_later!
+            else
+              UserMailer.webauthn_credential_added(current_user, user_credential).deliver_later!
+            end
+          else
+            flash[:error] = I18n.t('webauthn_credentials.create.error')
+            status = :internal_server_error
+          end
+        else
+          flash[:error] = t('webauthn_credentials.create.error')
+          status = :unauthorized
+        end
+
+        render json: { redirect_path: settings_two_factor_authentication_methods_path }, status: status
+      end
+
+      def destroy
+        credential = current_user.webauthn_credentials.find_by(id: params[:id])
+        if credential
+          credential.destroy
+          if credential.destroyed?
+            flash[:success] = I18n.t('webauthn_credentials.destroy.success')
+
+            if current_user.webauthn_credentials.empty?
+              UserMailer.webauthn_disabled(current_user).deliver_later!
+            else
+              UserMailer.webauthn_credential_deleted(current_user, credential).deliver_later!
+            end
+          else
+            flash[:error] = I18n.t('webauthn_credentials.destroy.error')
+          end
+        else
+          flash[:error] = I18n.t('webauthn_credentials.destroy.error')
+        end
+        redirect_to settings_two_factor_authentication_methods_path
+      end
+
+      private
+
+      def require_otp_enabled
+        unless current_user.otp_enabled?
+          flash[:error] = t('webauthn_credentials.otp_required')
+          redirect_to settings_two_factor_authentication_methods_path
+        end
+      end
+
+      def require_webauthn_enabled
+        unless current_user.webauthn_enabled?
+          flash[:error] = t('webauthn_credentials.not_enabled')
+          redirect_to settings_two_factor_authentication_methods_path
+        end
+      end
+    end
+  end
+end