69 lines
1.7 KiB
Ruby
69 lines
1.7 KiB
Ruby
module Gitlab
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# An untrusted regular expression is any regexp containing patterns sourced
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# from user input.
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#
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# Ruby's built-in regular expression library allows patterns which complete in
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# exponential time, permitting denial-of-service attacks.
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#
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# Not all regular expression features are available in untrusted regexes, and
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# there is a strict limit on total execution time. See the RE2 documentation
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# at https://github.com/google/re2/wiki/Syntax for more details.
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class UntrustedRegexp
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delegate :===, to: :regexp
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def initialize(pattern)
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@regexp = RE2::Regexp.new(pattern, log_errors: false)
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raise RegexpError.new(regexp.error) unless regexp.ok?
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end
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def replace_all(text, rewrite)
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RE2.GlobalReplace(text, regexp, rewrite)
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end
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def scan(text)
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text = text.dup # modified in-place
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results = []
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loop do
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match = scan_regexp.match(text)
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break unless match
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# Ruby scan returns empty strings, not nil
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groups = match.to_a.map(&:to_s)
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results <<
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if regexp.number_of_capturing_groups.zero?
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groups[0]
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else
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groups[1..-1]
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end
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text.slice!(0, match.end(0) || 1)
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break unless text.present?
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end
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results
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end
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def replace(text, rewrite)
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RE2.Replace(text, regexp, rewrite)
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end
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private
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attr_reader :regexp
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# RE2 scan operates differently to Ruby scan when there are no capture
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# groups, so work around it
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def scan_regexp
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@scan_regexp ||=
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if regexp.number_of_capturing_groups.zero?
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RE2::Regexp.new('(' + regexp.source + ')')
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else
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regexp
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end
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end
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end
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end
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