discourse/lib/topic_upload_security_manager.rb

# frozen_string_literal: true

##
# There are certain conditions with secure media when the security of
# uploads will need to change depending on the context they reside in.
#
# For example on these conditions:
#  * Topic category change
#  * Topic switching between PM and public topic
#  * Post moving between topics
#
# We need to go through all of the posts in that topic that
# own uploads via access_control_post_id, then for those uploads determine
# if they still need to be secure or not. For example an upload could be
# secure if it is in a PM, and then when the topic gets converted to a public
# topic the upload no longer needs to remain secure as it is no longer in
# a secure context.
class TopicUploadSecurityManager
  def initialize(topic)
    @topic = topic
  end

  def run
    Rails.logger.debug("Updating upload security in topic #{@topic.id}")
    posts_owning_uploads.each do |post|
      Post.transaction do
        Rails.logger.debug("Updating upload security in topic #{@topic.id} - post #{post.id}")
        post.topic = @topic

        secure_status_did_change = post.owned_uploads_via_access_control.any? do |upload|
          # 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(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}")
      end
    end

    return if !SiteSetting.secure_media

    # we only want to do this if secure media is enabled. if
    # the setting is turned on after a site has been running
    # already, we want to make sure that any post moves after
    # this are handled and upload secure statuses and ACLs
    # are updated appropriately, as well as setting the access control
    # post for secure uploads missing it.
    #
    # examples (all after secure media is enabled):
    #
    #  -> a public topic is moved to a private category after
    #  -> a PM is converted to a public topic
    #  -> a public topic is converted to a PM
    #  -> a topic is moved from a private to a public category
    posts_with_unowned_uploads.each do |post|
      Post.transaction do
        Rails.logger.debug("Setting upload access control posts in topic #{@topic.id} - post #{post.id}")
        post.topic = @topic

        secure_status_did_change = post.uploads.any? do |upload|
          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(source: "topic upload security")
          else
            false
          end
        end

        post.rebake! if secure_status_did_change
        Rails.logger.debug("Completed changing access control posts #{secure_status_did_change ? 'and rebaking' : ''} in topic #{@topic.id} - post #{post.id}")
      end
    end

    Rails.logger.debug("Completed updating upload security in topic #{@topic.id}!")
  end

  private

  def posts_owning_uploads
    Post.where(topic_id: @topic.id).joins('INNER JOIN uploads ON access_control_post_id = posts.id')
  end

  def posts_with_unowned_uploads
    Post
      .where(topic_id: @topic.id)
      .joins('INNER JOIN post_uploads ON post_uploads.post_id = posts.id')
      .joins('INNER JOIN uploads ON post_uploads.upload_id = uploads.id')
      .where('uploads.access_control_post_id IS NULL')
      .includes(:uploads)
  end
end