Merge commit '272592d16d40e804ec325ef3b5e6de9bbad5f2dd' into glitch-soc/merge-upstream

Conflicts:
- `.rubocop_todo.yml`:
  Upstream fixed a bunch lint issues, and changed the `Max` parameter of the
  `Metrics/AbcSize` cop.
  Glitch-soc has different code and slightly higher `AbcSize` complexity,
  modified the `.rubocop_todo.yml` file accordingly.
- `app/policies/status_policy.rb`:
  Upstream changed `account.suspended?` to `account.unavailable?` to prepare
  for delete flags. Glitch-soc has additional local-only conditions.
  Ported upstream's refactor while keeping glitch-soc's additional condition.
- `app/serializers/initial_state_serializer.rb`:
  Upstream refactored a bunch of stuff while glitch-soc has more settings.
  Refactored as upstream did while keeping glitch-soc's settings.

app/controllers/concerns/auth/two_factor_authentication_concern.rb

@@ -0,0 +1,99 @@
+# frozen_string_literal: true
+
+module Auth::TwoFactorAuthenticationConcern
+  extend ActiveSupport::Concern
+
+  included do
+    prepend_before_action :authenticate_with_two_factor, if: :two_factor_enabled?, only: [:create]
+    helper_method :webauthn_enabled?
+  end
+
+  def two_factor_enabled?
+    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)
+    user.validate_and_consume_otp!(user_params[:otp_attempt]) ||
+      user.invalidate_otp_backup_code!(user_params[:otp_attempt])
+  rescue OpenSSL::Cipher::CipherError
+    false
+  end
+
+  def authenticate_with_two_factor
+    if user_params[:email].present?
+      user = self.resource = find_user_from_params
+      prompt_for_two_factor(user) if user&.external_or_valid_password?(user_params[:password])
+    elsif session[:attempt_user_id]
+      user = self.resource = User.find_by(id: session[:attempt_user_id])
+      return if user.nil?
+
+      if session[:attempt_user_updated_at] != user.updated_at.to_s
+        restart_session
+      elsif user.webauthn_enabled? && user_params.key?(:credential)
+        authenticate_with_two_factor_via_webauthn(user)
+      elsif user_params.key?(:otp_attempt)
+        authenticate_with_two_factor_via_otp(user)
+      end
+    end
+  end
+
+  def authenticate_with_two_factor_via_webauthn(user)
+    webauthn_credential = WebAuthn::Credential.from_get(user_params[:credential])
+
+    if valid_webauthn_credential?(user, webauthn_credential)
+      on_authentication_success(user, :webauthn)
+      render json: { redirect_path: after_sign_in_path_for(user) }, status: 200
+    else
+      on_authentication_failure(user, :webauthn, :invalid_credential)
+      render json: { error: t('webauthn_credentials.invalid_credential') }, status: 422
+    end
+  end
+
+  def authenticate_with_two_factor_via_otp(user)
+    if valid_otp_attempt?(user)
+      on_authentication_success(user, :otp)
+    else
+      on_authentication_failure(user, :otp, :invalid_otp_token)
+      flash.now[:alert] = I18n.t('users.invalid_otp_token')
+      prompt_for_two_factor(user)
+    end
+  end
+
+  def prompt_for_two_factor(user)
+    register_attempt_in_session(user)
+
+    use_pack 'auth'
+
+    @body_classes     = 'lighter'
+    @webauthn_enabled = user.webauthn_enabled?
+    @scheme_type      = if user.webauthn_enabled? && user_params[:otp_attempt].blank?
+                          'webauthn'
+                        else
+                          'totp'
+                        end
+
+    set_locale { render :two_factor }
+  end
+
+  protected
+
+  def webauthn_enabled?
+    @webauthn_enabled
+  end
+end