62 lines
1.5 KiB
Ruby
62 lines
1.5 KiB
Ruby
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# frozen_string_literal: true
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module Gitlab
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module Middleware
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# There is no valid reason for a request to contain a null byte (U+0000)
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# so just return HTTP 400 (Bad Request) if we receive one
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class HandleNullBytes
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NULL_BYTE_REGEX = Regexp.new(Regexp.escape("\u0000")).freeze
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attr_reader :app
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def initialize(app)
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@app = app
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end
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def call(env)
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return [400, {}, ["Bad Request"]] if request_has_null_byte?(env)
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app.call(env)
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end
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private
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def request_has_null_byte?(request)
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return false if ENV['REJECT_NULL_BYTES'] == "1"
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request = Rack::Request.new(request)
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request.params.values.any? do |value|
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param_has_null_byte?(value)
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end
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end
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def param_has_null_byte?(value, depth = 0)
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# Guard against possible attack sending large amounts of nested params
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# Should be safe as deeply nested params are highly uncommon.
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return false if depth > 2
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depth += 1
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if value.respond_to?(:match)
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string_contains_null_byte?(value)
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elsif value.respond_to?(:values)
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value.values.any? do |hash_value|
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param_has_null_byte?(hash_value, depth)
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end
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elsif value.is_a?(Array)
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value.any? do |array_value|
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param_has_null_byte?(array_value, depth)
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end
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else
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false
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end
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end
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def string_contains_null_byte?(string)
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string.match?(NULL_BYTE_REGEX)
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end
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end
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end
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end
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