discourse/lib/upload_security.rb

85 lines
2.9 KiB
Ruby

# frozen_string_literal: true
##
# A note on determining whether an upload should be marked as secure:
#
# 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.
#
# 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.
class UploadSecurity
def initialize(upload, opts = {})
@upload = upload
@opts = opts
@upload_type = @opts[:type]
end
def should_be_secure?
return false if uploading_in_public_context?
secure_attachment? || secure_media?
end
private
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?
end
def supported_media?
FileHelper.is_supported_media?(@upload.original_filename)
end
def secure_attachment?
!supported_media? && SiteSetting.prevent_anons_from_downloading_files
end
def secure_media?
SiteSetting.secure_media? && supported_media? && uploading_in_secure_context?
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?
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.
# if that post is with_secure_media? then the upload should also be secure.
# 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?
end
def public_type?
%w[avatar custom_emoji profile_background card_background].include?(@upload_type)
end
def uploading_in_composer?
@upload_type == "composer"
end
def used_for_custom_emoji?
@upload.id.present? && CustomEmoji.exists?(upload_id: @upload.id)
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")
end
end