53 lines
1.5 KiB
Ruby
53 lines
1.5 KiB
Ruby
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# frozen_string_literal: true
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# == Sanitizable concern
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#
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# This concern adds HTML sanitization and validation to models. The intention is
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# to help prevent XSS attacks in the event of a by-pass in the frontend
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# sanitizer due to a configuration issue or a vulnerability in the sanitizer.
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# This approach is commonly referred to as defense-in-depth.
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#
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# Example:
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#
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# module Dast
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# class Profile < ApplicationRecord
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# include Sanitizable
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#
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# sanitizes! :name, :description
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module Sanitizable
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extend ActiveSupport::Concern
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class_methods do
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def sanitize(input)
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return unless input
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# We return the input unchanged to avoid escaping pre-escaped HTML fragments.
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# Please see gitlab-org/gitlab#293634 for an example.
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return input unless input == CGI.unescapeHTML(input.to_s)
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CGI.unescapeHTML(Sanitize.fragment(input))
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end
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def sanitizes!(*attrs)
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instance_eval do
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before_validation do
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attrs.each do |attr|
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input = public_send(attr) # rubocop: disable GitlabSecurity/PublicSend
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public_send("#{attr}=", self.class.sanitize(input)) # rubocop: disable GitlabSecurity/PublicSend
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end
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end
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validates_each(*attrs) do |record, attr, input|
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# We reject pre-escaped HTML fragments as invalid to avoid saving them
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# to the database.
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unless input.to_s == CGI.unescapeHTML(input.to_s)
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record.errors.add(attr, 'cannot contain escaped HTML entities')
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end
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end
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end
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end
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end
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end
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