replace the upload type whitelist with a sanitizer

app/controllers/uploads_controller.rb

@@ -5,9 +5,8 @@ class UploadsController < ApplicationController
   skip_before_filter :preload_json, :check_xhr, :redirect_to_login_if_required, only: [:show]
 
   def create
-    type = params.require(:type)
-
-    raise Discourse::InvalidAccess.new unless Upload::UPLOAD_TYPES.include?(type)
+    # 50 characters ought to be enough for the upload type
+    type = params.require(:type).parameterize("_")[0..50]
 
     if type == "avatar" && (SiteSetting.sso_overrides_avatar || !SiteSetting.allow_uploaded_avatars)
       return render json: failed_json, status: 422

app/models/upload.rb

@@ -21,9 +21,6 @@ class Upload < ActiveRecord::Base
 
   validates_with ::Validators::UploadValidator
 
-  CROPPED_TYPES ||= %w{avatar card_background custom_emoji profile_background}.each(&:freeze)
-  UPLOAD_TYPES  ||= CROPPED_TYPES + %w{composer category_logo category_background wizard_logo_url wizard_logo_small_url wizard_favicon_url wizard_apple_touch_icon_url}.each(&:freeze)
-
   def thumbnail(width = self.width, height = self.height)
     optimized_images.find_by(width: width, height: height)
   end

lib/upload_creator.rb

@@ -5,10 +5,12 @@ class UploadCreator
 
   TYPES_CONVERTED_TO_JPEG ||= %i{bmp png}
 
+  TYPES_TO_CROP ||= %w{avatar card_background custom_emoji profile_background}.each(&:freeze)
+
   WHITELISTED_SVG_ELEMENTS ||= %w{
     circle clippath defs ellipse g line linearGradient path polygon polyline
     radialGradient rect stop svg text textpath tref tspan use
-  }
+  }.each(&:freeze)
 
   # Available options
   #  - type (string)
@@ -177,7 +179,7 @@ class UploadCreator
   end
 
   def should_crop?
-    Upload::CROPPED_TYPES.include?(@opts[:type])
+    TYPES_TO_CROP.include?(@opts[:type])
   end
 
   def crop!

spec/controllers/uploads_controller_spec.rb

@@ -33,18 +33,13 @@ describe UploadsController do
         })
       end
 
-      it 'fails if type is invalid' do
-        xhr :post, :create, file: logo, type: "invalid type cause has space"
-        expect(response.status).to eq 403
+      it 'expects a type' do
+        expect { xhr :post, :create, file: logo }.to raise_error(ActionController::ParameterMissing)
+      end
 
-        xhr :post, :create, file: logo, type: "\\invalid"
-        expect(response.status).to eq 403
-
-        xhr :post, :create, file: logo, type: "invalid."
-        expect(response.status).to eq 403
-
-        xhr :post, :create, file: logo, type: "toolong"*100
-        expect(response.status).to eq 403
+      it 'parameterize the type' do
+        subject.expects(:create_upload).with(logo, nil, "super_long_type_with_charssuper_long_type_with_char")
+        xhr :post, :create, file: logo, type: "super \# long \//\\ type with \\. $%^&*( chars" * 5
       end
 
       it 'is successful with an image' do