129 lines
3.7 KiB
Ruby
129 lines
3.7 KiB
Ruby
# frozen_string_literal: true
|
|
|
|
module Gitlab
|
|
# An untrusted regular expression is any regexp containing patterns sourced
|
|
# from user input.
|
|
#
|
|
# Ruby's built-in regular expression library allows patterns which complete in
|
|
# exponential time, permitting denial-of-service attacks.
|
|
#
|
|
# Not all regular expression features are available in untrusted regexes, and
|
|
# there is a strict limit on total execution time. See the RE2 documentation
|
|
# at https://github.com/google/re2/wiki/Syntax for more details.
|
|
class UntrustedRegexp
|
|
require_dependency 're2'
|
|
|
|
# recreate Ruby's \R metacharacter
|
|
# https://ruby-doc.org/3.2.2/Regexp.html#class-Regexp-label-Character+Classes
|
|
BACKSLASH_R = '(\n|\v|\f|\r|\x{0085}|\x{2028}|\x{2029}|\r\n)'
|
|
|
|
delegate :===, :source, to: :regexp
|
|
|
|
def initialize(pattern, multiline: false)
|
|
if multiline
|
|
pattern = "(?m)#{pattern}"
|
|
end
|
|
|
|
@regexp = RE2::Regexp.new(pattern, log_errors: false)
|
|
|
|
raise RegexpError, regexp.error unless regexp.ok?
|
|
end
|
|
|
|
def replace_all(text, rewrite)
|
|
RE2.GlobalReplace(text, regexp, rewrite)
|
|
end
|
|
|
|
# There is no built-in replace with block support (like `gsub`). We can accomplish
|
|
# the same thing by parsing and rebuilding the string with the substitutions.
|
|
def replace_gsub(text)
|
|
new_text = +''
|
|
remainder = text
|
|
|
|
matched = match(remainder)
|
|
|
|
until matched.nil? || matched.to_a.compact.empty?
|
|
partitioned = remainder.partition(matched.to_s)
|
|
new_text << partitioned.first
|
|
remainder = partitioned.last
|
|
|
|
new_text << yield(matched)
|
|
|
|
matched = match(remainder)
|
|
end
|
|
|
|
new_text << remainder
|
|
end
|
|
|
|
def scan(text)
|
|
matches = scan_regexp.scan(text).to_a
|
|
matches.map!(&:first) if regexp.number_of_capturing_groups == 0
|
|
matches
|
|
end
|
|
|
|
def match(text)
|
|
scan_regexp.match(text)
|
|
end
|
|
|
|
def match?(text)
|
|
text.present? && scan(text).present?
|
|
end
|
|
|
|
def replace(text, rewrite)
|
|
RE2.Replace(text, regexp, rewrite)
|
|
end
|
|
|
|
# #scan returns an array of the groups captured, rather than MatchData.
|
|
# Use this to give the capture group name and grab the proper value
|
|
def extract_named_group(name, match)
|
|
return unless match
|
|
|
|
match_position = regexp.named_capturing_groups[name.to_s]
|
|
raise RegexpError, "Invalid named capture group: #{name}" unless match_position
|
|
|
|
match[match_position - 1]
|
|
end
|
|
|
|
def ==(other)
|
|
self.source == other.source
|
|
end
|
|
|
|
# Handles regular expressions with the preferred RE2 library where possible
|
|
# via UntustedRegex. Falls back to Ruby's built-in regular expression library
|
|
# when the syntax would be invalid in RE2.
|
|
#
|
|
# One difference between these is `(?m)` multi-line mode. Ruby regex enables
|
|
# this by default, but also handles `^` and `$` differently.
|
|
# See: https://www.regular-expressions.info/modifiers.html
|
|
def self.with_fallback(pattern, multiline: false)
|
|
UntrustedRegexp.new(pattern, multiline: multiline)
|
|
rescue RegexpError
|
|
raise if Feature.enabled?(:disable_unsafe_regexp)
|
|
|
|
if Feature.enabled?(:ci_unsafe_regexp_logger, type: :ops)
|
|
Gitlab::AppJsonLogger.info(
|
|
class: self.name,
|
|
regexp: pattern.to_s,
|
|
fabricated: 'unsafe ruby regexp'
|
|
)
|
|
end
|
|
|
|
Regexp.new(pattern)
|
|
end
|
|
|
|
private
|
|
|
|
attr_reader :regexp
|
|
|
|
# RE2 scan operates differently to Ruby scan when there are no capture
|
|
# groups, so work around it
|
|
def scan_regexp
|
|
@scan_regexp ||=
|
|
if regexp.number_of_capturing_groups == 0
|
|
RE2::Regexp.new('(' + regexp.source + ')')
|
|
else
|
|
regexp
|
|
end
|
|
end
|
|
end
|
|
end
|