104 lines
3.3 KiB
Ruby
104 lines
3.3 KiB
Ruby
# frozen_string_literal: true
|
|
|
|
module Gitlab
|
|
module Middleware
|
|
# There is no valid reason for a request to contain a malformed string
|
|
# so just return HTTP 400 (Bad Request) if we receive one
|
|
class HandleMalformedStrings
|
|
include ActionController::HttpAuthentication::Basic
|
|
|
|
NULL_BYTE_REGEX = Regexp.new(Regexp.escape("\u0000")).freeze
|
|
|
|
attr_reader :app
|
|
|
|
def initialize(app)
|
|
@app = app
|
|
end
|
|
|
|
def call(env)
|
|
return [400, { 'Content-Type' => 'text/plain' }, ['Bad Request']] if request_contains_malformed_string?(env)
|
|
|
|
app.call(env)
|
|
end
|
|
|
|
private
|
|
|
|
def request_contains_malformed_string?(env)
|
|
return false if ENV['DISABLE_REQUEST_VALIDATION'] == '1'
|
|
|
|
# Duplicate the env, so it is not modified when accessing the parameters
|
|
# https://github.com/rails/rails/blob/34991a6ae2fc68347c01ea7382fa89004159e019/actionpack/lib/action_dispatch/http/parameters.rb#L59
|
|
# The modification causes problems with our multipart middleware
|
|
request = ActionDispatch::Request.new(env.dup)
|
|
|
|
return true if malformed_path?(request.path)
|
|
return true if credentials_malformed?(request)
|
|
|
|
request.params.values.any? do |value|
|
|
param_has_null_byte?(value)
|
|
end
|
|
rescue ActionController::BadRequest
|
|
# If we can't build an ActionDispatch::Request something's wrong
|
|
# This would also happen if `#params` contains invalid UTF-8
|
|
# in this case we'll return a 400
|
|
#
|
|
true
|
|
end
|
|
|
|
def malformed_path?(path)
|
|
string_malformed?(Rack::Utils.unescape(path))
|
|
rescue ArgumentError
|
|
# Rack::Utils.unescape raised this, path is malformed.
|
|
true
|
|
end
|
|
|
|
def credentials_malformed?(request)
|
|
credentials = if has_basic_credentials?(request)
|
|
decode_credentials(request).presence
|
|
else
|
|
request.authorization.presence
|
|
end
|
|
|
|
return false unless credentials
|
|
|
|
string_malformed?(credentials)
|
|
end
|
|
|
|
def param_has_null_byte?(value, depth = 0)
|
|
# Guard against possible attack sending large amounts of nested params
|
|
# Should be safe as deeply nested params are highly uncommon.
|
|
return false if depth > 2
|
|
|
|
depth += 1
|
|
|
|
if value.respond_to?(:match)
|
|
string_malformed?(value)
|
|
elsif value.respond_to?(:values)
|
|
value.values.any? do |hash_value|
|
|
param_has_null_byte?(hash_value, depth)
|
|
end
|
|
elsif value.is_a?(Array)
|
|
value.any? do |array_value|
|
|
param_has_null_byte?(array_value, depth)
|
|
end
|
|
else
|
|
false
|
|
end
|
|
end
|
|
|
|
def string_malformed?(string)
|
|
# We're using match rather than include, because that will raise an ArgumentError
|
|
# when the string contains invalid UTF8
|
|
#
|
|
# We try to encode the string from ASCII-8BIT to UTF8. If we failed to do
|
|
# so for certain characters in the string, those chars are probably incomplete
|
|
# multibyte characters.
|
|
string.dup.force_encoding(Encoding::UTF_8).match?(NULL_BYTE_REGEX)
|
|
|
|
rescue ArgumentError, Encoding::UndefinedConversionError
|
|
# If we're here, we caught a malformed string. Return true
|
|
true
|
|
end
|
|
end
|
|
end
|
|
end
|