DEV: Add security_last_changed_at and security_last_changed_reason to uploads (#11860)

This PR adds security_last_changed_at and security_last_changed_reason to uploads. This has been done to make it easier to track down why an upload's secure column has changed and when. This necessitated a refactor of the UploadSecurity class to provide reasons why the upload security would have changed.

As well as this, a source is now provided from the location which called for the upload's security status to be updated as they are several (e.g. post creator, topic security updater, rake tasks, manual change).

app/models/post.rb

@@ -951,9 +951,9 @@ class Post < ActiveRecord::Base
     end
   end
 
-  def update_uploads_secure_status
+  def update_uploads_secure_status(source:)
     if Discourse.store.external?
-      self.uploads.each { |upload| upload.update_secure_status }
+      self.uploads.each { |upload| upload.update_secure_status(source: source) }
     end
   end
 

app/models/topic.rb

@@ -865,6 +865,14 @@ class Topic < ActiveRecord::Base
             Jobs.enqueue(:notify_category_change, post_id: post.id, notified_user_ids: notified_user_ids)
           end
         end
+
+        # when a topic changes category we may need to make uploads
+        # linked to posts secure/not secure depending on whether the
+        # category is private. this is only done if the category
+        # has actually changed to avoid noise.
+        DB.after_commit do
+          Jobs.enqueue(:update_topic_upload_security, topic_id: self.id)
+        end
       end
 
       Category.where(id: new_category.id).update_all("topic_count = topic_count + 1")
@@ -873,13 +881,6 @@ class Topic < ActiveRecord::Base
         CategoryFeaturedTopic.feature_topics_for(old_category) unless @import_mode
         CategoryFeaturedTopic.feature_topics_for(new_category) unless @import_mode || old_category.try(:id) == new_category.id
       end
-
-      # when a topic changes category we may need to make uploads
-      # linked to posts secure/not secure depending on whether the
-      # category is private
-      DB.after_commit do
-        Jobs.enqueue(:update_topic_upload_security, topic_id: self.id)
-      end
     end
 
     true

app/models/upload.rb

@@ -311,16 +311,30 @@ class Upload < ActiveRecord::Base
     self.posts.where("cooked LIKE '%/_optimized/%'").find_each(&:rebake!)
   end
 
-  def update_secure_status(secure_override_value: nil)
-    mark_secure = secure_override_value.nil? ? UploadSecurity.new(self).should_be_secure? : secure_override_value
+  def update_secure_status(source: "unknown", override: nil)
+    if override.nil?
+      mark_secure, reason = UploadSecurity.new(self).should_be_secure_with_reason
+    else
+      mark_secure = override
+      reason = "manually overridden"
+    end
 
     secure_status_did_change = self.secure? != mark_secure
-    self.update_column("secure", mark_secure)
+    self.update(secure_params(mark_secure, reason, source))
+
     Discourse.store.update_upload_ACL(self) if Discourse.store.external?
 
     secure_status_did_change
   end
 
+  def secure_params(secure, reason, source = "unknown")
+    {
+      secure: secure,
+      security_last_changed_reason: reason + " | source: #{source}",
+      security_last_changed_at: Time.zone.now
+    }
+  end
+
   def self.migrate_to_new_scheme(limit: nil)
     problems = []
 
@@ -472,6 +486,8 @@ end
 #  original_sha1                :string
 #  verification_status          :integer          default(1), not null
 #  animated                     :boolean
+#  security_last_changed_at     :datetime
+#  security_last_changed_reason :string
 #
 # Indexes
 #

db/migrate/20210127013637_add_upload_security_log_columns.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+class AddUploadSecurityLogColumns < ActiveRecord::Migration[6.0]
+  def change
+    add_column :uploads, :security_last_changed_at, :datetime, null: true
+    add_column :uploads, :security_last_changed_reason, :string, null: true
+  end
+end

lib/post_creator.rb

@@ -419,8 +419,7 @@ class PostCreator
   end
 
   def update_uploads_secure_status
-    return if !SiteSetting.secure_media?
-    @post.update_uploads_secure_status
+    @post.update_uploads_secure_status(source: "post creator") if SiteSetting.secure_media?
   end
 
   def delete_owned_bookmarks

lib/tasks/uploads.rake

@@ -650,7 +650,11 @@ end
 
 def mark_all_as_secure_login_required(uploads_to_update)
   puts "Marking #{uploads_to_update.count} upload(s) as secure because login_required is true.", ""
-  uploads_to_update.update_all(secure: true)
+  uploads_to_update.update_all(
+    secure: true,
+    security_last_changed_at: Time.zone.now,
+    security_last_changed_reason: "upload security rake task all secure login required"
+  )
   puts "Finished marking upload(s) as secure."
 end
 
@@ -665,11 +669,19 @@ end
 def update_specific_upload_security_no_login_required(upload_ids_to_mark_as_secure, upload_ids_to_mark_as_not_secure)
   if upload_ids_to_mark_as_secure.any?
     puts "Marking #{upload_ids_to_mark_as_secure.length} uploads as secure because UploadSecurity determined them to be secure."
-    Upload.where(id: upload_ids_to_mark_as_secure).update_all(secure: true)
+    Upload.where(id: upload_ids_to_mark_as_secure).update_all(
+      secure: true,
+      security_last_changed_at: Time.zone.now,
+      security_last_changed_reason: "upload security rake task mark as secure"
+    )
   end
   if upload_ids_to_mark_as_not_secure.any?
     puts "Marking #{upload_ids_to_mark_as_not_secure.length} uploads as not secure because UploadSecurity determined them to be not secure."
-    Upload.where(id: upload_ids_to_mark_as_not_secure).update_all(secure: false)
+    Upload.where(id: upload_ids_to_mark_as_not_secure).update_all(
+      secure: false,
+      security_last_changed_at: Time.zone.now,
+      security_last_changed_reason: "upload security rake task mark as not secure"
+    )
   end
   puts "Finished updating upload security."
 end

lib/topic_upload_security_manager.rb

@@ -31,7 +31,7 @@ class TopicUploadSecurityManager
           # we have already got the post preloaded so we may as well
           # attach it here to avoid another load in UploadSecurity
           upload.access_control_post = post
-          upload.update_secure_status
+          upload.update_secure_status(source: "topic upload security")
         end
         post.rebake! if secure_status_did_change
         Rails.logger.debug("Security updated & rebake complete in topic #{@topic.id} - post #{post.id}")
@@ -62,7 +62,7 @@ class TopicUploadSecurityManager
           first_post_upload_appeared_in = upload.post_uploads.first.post
           if first_post_upload_appeared_in == post
             upload.update(access_control_post: post)
-            upload.update_secure_status
+            upload.update_secure_status(source: "topic upload security")
           else
             false
           end

lib/upload_creator.rb

@@ -130,6 +130,13 @@ class UploadCreator
       end
 
       add_metadata!
+
+      if SiteSetting.secure_media
+        secure, reason = UploadSecurity.new(@upload, @opts.merge(creating: true)).should_be_secure_with_reason
+        attrs = @upload.secure_params(secure, reason, "upload creator")
+        @upload.assign_attributes(attrs)
+      end
+
       return @upload unless @upload.save
 
       DiscourseEvent.trigger(:before_upload_creation, @file, is_image, @opts[:for_export])
@@ -424,7 +431,6 @@ class UploadCreator
     @upload.for_export          = true if @opts[:for_export]
     @upload.for_site_setting    = true if @opts[:for_site_setting]
     @upload.for_gravatar        = true if @opts[:for_gravatar]
-    @upload.secure = UploadSecurity.new(@upload, @opts).should_be_secure?
   end
 
   private

lib/upload_security.rb

@@ -5,14 +5,16 @@
 #
 # Some of these flags checked (e.g. all of the for_X flags and the opts[:type])
 # are only set when _initially uploading_ via UploadCreator and are not present
-# when an upload already exists.
+# when an upload already exists, these will only be checked when the @creating
+# option is present.
 #
 # If the upload already exists the best way to figure out whether it should be
 # secure alongside the site settings is the access_control_post_id, because the
 # original post the upload is linked to has far more bearing on its security context
 # post-upload. If the access_control_post_id does not exist then we just rely
 # on the current secure? status, otherwise there would be a lot of additional
-# complex queries and joins to perform.
+# complex queries and joins to perform. Over time more of these specific
+# queries will be implemented.
 class UploadSecurity
   @@custom_public_types = []
 
@@ -38,32 +40,52 @@ class UploadSecurity
     @upload = upload
     @opts = opts
     @upload_type = @opts[:type]
+    @creating = @opts[:creating]
   end
 
   def should_be_secure?
-    return false if !SiteSetting.secure_media?
-    return false if uploading_in_public_context?
-    uploading_in_secure_context?
+    should_be_secure_with_reason.first
   end
 
-  def uploading_in_public_context?
-    @upload.for_theme ||
-      @upload.for_site_setting ||
-      @upload.for_gravatar ||
-      public_type? ||
-      used_for_custom_emoji? ||
-      based_on_regular_emoji?
+  def should_be_secure_with_reason
+    insecure_context_checks.each do |check, reason|
+      return [false, reason] if perform_check(check)
+    end
+    secure_context_checks.each do |check, reason|
+      return [perform_check(check), reason] if priority_check?(check)
+      return [true, reason] if perform_check(check)
     end
 
-  def uploading_in_secure_context?
-    return true if SiteSetting.login_required?
-    if @upload.access_control_post_id.present?
-      return access_control_post_has_secure_media?
-    end
-    uploading_in_composer? || @upload.for_private_message || @upload.for_group_message || @upload.secure?
+    [false, "no checks satisfied"]
   end
 
-  private
+  def secure_media_disabled_check
+    !SiteSetting.secure_media?
+  end
+
+  def insecure_creation_for_modifiers_check
+    return false if !@creating
+    @upload.for_theme || @upload.for_site_setting || @upload.for_gravatar
+  end
+
+  def public_type_check
+    PUBLIC_TYPES.include?(@upload_type) || @@custom_public_types.include?(@upload_type)
+  end
+
+  def custom_emoji_check
+    @upload.id.present? && CustomEmoji.exists?(upload_id: @upload.id)
+  end
+
+  def regular_emoji_check
+    return false if @upload.origin.blank?
+    uri = URI.parse(@upload.origin)
+    return true if Emoji.all.map(&:url).include?("#{uri.path}?#{uri.query}")
+    uri.path.include?("images/emoji")
+  end
+
+  def login_required_check
+    SiteSetting.login_required?
+  end
 
   # whether the upload should remain secure or not after posting depends on its context,
   # which is based on the post it is linked to via access_control_post_id.
@@ -71,28 +93,59 @@ class UploadSecurity
   # this may change to false if the upload was set to secure on upload e.g. in
   # a post composer then it turned out that the post itself was not in a secure context
   #
-  # if there is no access control post id and the upload is currently secure, we
-  # do not want to make it un-secure to avoid unintentionally exposing it
-  def access_control_post_has_secure_media?
-    @upload.access_control_post.with_secure_media?
+  # a post is with secure media if it is a private message or in a read restricted
+  # category
+  def access_control_post_has_secure_media_check
+    access_control_post&.with_secure_media?
   end
 
-  def public_type?
-    PUBLIC_TYPES.include?(@upload_type) || @@custom_public_types.include?(@upload_type)
-  end
-
-  def uploading_in_composer?
+  def uploading_in_composer_check
     @upload_type == "composer"
   end
 
-  def used_for_custom_emoji?
-    @upload.id.present? && CustomEmoji.exists?(upload_id: @upload.id)
+  def secure_creation_for_modifiers_check
+    return false if !@creating
+    @upload.for_private_message || @upload.for_group_message
   end
 
-  def based_on_regular_emoji?
-    return false if @upload.origin.blank?
-    uri = URI.parse(@upload.origin)
-    return true if Emoji.all.map(&:url).include?("#{uri.path}?#{uri.query}")
-    uri.path.include?("images/emoji")
+  def already_secure_check
+    @upload.secure?
+  end
+
+  private
+
+  def access_control_post
+    @access_control_post ||= @upload.access_control_post_id.present? ? @upload.access_control_post : nil
+  end
+
+  def insecure_context_checks
+    {
+      secure_media_disabled: "secure media is disabled",
+      insecure_creation_for_modifiers: "one or more creation for_modifiers was satisfied",
+      public_type: "upload is public type",
+      custom_emoji: "upload is used for custom emoji",
+      regular_emoji: "upload is used for regular emoji"
+    }
+  end
+
+  def secure_context_checks
+    {
+      login_required: "login is required",
+      access_control_post_has_secure_media: "access control post dictates security",
+      secure_creation_for_modifiers: "one or more creation for_modifiers was satisfied",
+      uploading_in_composer: "uploading via the composer",
+      already_secure: "upload is already secure"
+    }
+  end
+
+  # the access control check is important because that is the truest indicator
+  # of whether an upload should be secure or not, and thus should be returned
+  # immediately if there is an access control post
+  def priority_check?(check)
+    check == :access_control_post_has_secure_media && access_control_post
+  end
+
+  def perform_check(check)
+    send("#{check}_check")
   end
 end

spec/components/email/sender_spec.rb

@@ -439,7 +439,7 @@ describe Email::Sender do
         @secure_image_file = file_from_fixtures("logo.png", "images")
         @secure_image = UploadCreator.new(@secure_image_file, "logo.png")
           .create_for(Discourse.system_user.id)
-        @secure_image.update_secure_status(secure_override_value: true)
+        @secure_image.update_secure_status(override: true)
         @secure_image.update(access_control_post_id: reply.id)
         reply.update(raw: reply.raw + "\n" + "#{UploadMarkdown.new(@secure_image).image_markdown}")
         reply.rebake!

spec/lib/upload_security_spec.rb

@@ -7,7 +7,7 @@ RSpec.describe UploadSecurity do
   let(:post_in_secure_context) { Fabricate(:post, topic: Fabricate(:topic, category: private_category)) }
   fab!(:upload) { Fabricate(:upload) }
   let(:type) { nil }
-  let(:opts) { { type: type } }
+  let(:opts) { { type: type, creating: true } }
   subject { described_class.new(upload, opts) }
 
   context "when secure media is enabled" do

spec/models/post_spec.rb

@@ -1495,7 +1495,7 @@ describe Post do
         SiteSetting.secure_media = true
         post = Fabricate(:post, raw: raw, user: user, topic: Fabricate(:private_message_topic, user: user))
         post.link_post_uploads
-        post.update_uploads_secure_status
+        post.update_uploads_secure_status(source: "test")
 
         expect(PostUpload.where(post: post).joins(:upload).pluck(:upload_id, :secure)).to contain_exactly(
           [attachment_upload.id, true],
@@ -1507,7 +1507,7 @@ describe Post do
         SiteSetting.secure_media = false
         post = Fabricate(:post, raw: raw, user: user, topic: Fabricate(:private_message_topic, user: user))
         post.link_post_uploads
-        post.update_uploads_secure_status
+        post.update_uploads_secure_status(source: "test")
 
         expect(PostUpload.where(post: post).joins(:upload).pluck(:upload_id, :secure)).to contain_exactly(
           [attachment_upload.id, false],
@@ -1520,7 +1520,7 @@ describe Post do
         private_category = Fabricate(:private_category, group: Fabricate(:group))
         post = Fabricate(:post, raw: raw, user: user, topic: Fabricate(:topic, user: user, category: private_category))
         post.link_post_uploads
-        post.update_uploads_secure_status
+        post.update_uploads_secure_status(source: "test")
 
         expect(PostUpload.where(post: post).joins(:upload).pluck(:upload_id, :secure)).to contain_exactly(
           [attachment_upload.id, true],
@@ -1531,11 +1531,11 @@ describe Post do
       it "does not mark an upload as secure if it has already been used in a public topic" do
         post = Fabricate(:post, raw: raw, user: user, topic: Fabricate(:topic, user: user))
         post.link_post_uploads
-        post.update_uploads_secure_status
+        post.update_uploads_secure_status(source: "test")
 
         pm = Fabricate(:post, raw: raw, user: user, topic: Fabricate(:private_message_topic, user: user))
         pm.link_post_uploads
-        pm.update_uploads_secure_status
+        pm.update_uploads_secure_status(source: "test")
 
         expect(PostUpload.where(post: pm).joins(:upload).pluck(:upload_id, :secure)).to contain_exactly(
           [attachment_upload.id, false],

spec/models/upload_spec.rb

@@ -343,14 +343,14 @@ describe Upload do
   end
 
   describe '.update_secure_status' do
-    it "respects the secure_override_value parameter if provided" do
+    it "respects the override parameter if provided" do
       upload.update!(secure: true)
 
-      upload.update_secure_status(secure_override_value: true)
+      upload.update_secure_status(override: true)
 
       expect(upload.secure).to eq(true)
 
-      upload.update_secure_status(secure_override_value: false)
+      upload.update_secure_status(override: false)
 
       expect(upload.secure).to eq(false)
     end