import code from unmaintained ruby gem safe_ruby to local library

lib/discourse_chatbot/safe_ruby/lib/constant_whitelist.rb

@@ -0,0 +1,13 @@
+ALLOWED_CONSTANTS= [
+  :Object, :Module, :Class, :BasicObject, :Kernel, :NilClass, :NIL, :Data, :TrueClass, :TRUE, :FalseClass, :FALSE, :Encoding, 
+  :Comparable, :Enumerable, :String, :Symbol, :Exception, :SystemExit, :SignalException, :Interrupt, :StandardError, :TypeError,
+  :ArgumentError, :IndexError, :KeyError, :RangeError, :ScriptError, :SyntaxError, :LoadError, :NotImplementedError, :NameError,
+  :NoMethodError, :RuntimeError, :SecurityError, :NoMemoryError, :EncodingError, :SystemCallError, :Errno, :ZeroDivisionError,
+  :FloatDomainError, :Numeric, :Integer, :Fixnum, :Float, :Bignum, :Array, :Hash,  :Struct, :RegexpError, :Regexp,
+  :MatchData, :Marshal, :Range, :IOError, :EOFError, :IO, :STDIN, :STDOUT, :STDERR, :Time, :Random,
+  :Signal, :Proc, :LocalJumpError, :SystemStackError, :Method, :UnboundMethod, :Binding, :Math, :Enumerator,
+  :StopIteration, :RubyVM, :Thread, :TOPLEVEL_BINDING, :ThreadGroup, :Mutex, :ThreadError, :Fiber, :FiberError, :Rational, :Complex,
+  :RUBY_VERSION, :RUBY_RELEASE_DATE, :RUBY_PLATFORM, :RUBY_PATCHLEVEL, :RUBY_REVISION, :RUBY_DESCRIPTION, :RUBY_COPYRIGHT, :RUBY_ENGINE,
+  :TracePoint, :ARGV, :Gem, :RbConfig, :Config, :CROSS_COMPILING, :Date, :ConditionVariable, :Queue, :SizedQueue, :MonitorMixin, :Monitor,
+  :Exception2MessageMapper, :IRB, :RubyToken, :RubyLex, :Readline, :RUBYGEMS_ACTIVATION_MONITOR
+]

lib/discourse_chatbot/safe_ruby/lib/make_safe_code.rb

@@ -0,0 +1,51 @@
+MAKE_SAFE_CODE = <<-STRING
+def keep_singleton_methods(klass, singleton_methods)
+  klass = Object.const_get(klass)
+  singleton_methods = singleton_methods.map(&:to_sym)
+  undef_methods = (klass.singleton_methods - singleton_methods)
+
+  undef_methods.each do |method|
+    klass.singleton_class.send(:undef_method, method)
+  end
+
+end
+
+def keep_methods(klass, methods)
+  klass = Object.const_get(klass)
+  methods = methods.map(&:to_sym)
+  undef_methods = (klass.methods(false) - methods)
+  undef_methods.each do |method|
+    klass.send(:undef_method, method)
+  end
+end
+
+def clean_constants
+  (Object.constants - #{ALLOWED_CONSTANTS}).each do |const|
+    Object.send(:remove_const, const) if defined?(const)
+  end
+end
+
+keep_singleton_methods(:Kernel, #{KERNEL_S_METHODS})
+keep_singleton_methods(:Symbol, #{SYMBOL_S_METHODS})
+keep_singleton_methods(:String, #{STRING_S_METHODS})
+keep_singleton_methods(:IO, #{IO_S_METHODS})
+
+keep_methods(:Kernel, #{KERNEL_METHODS})
+keep_methods(:NilClass, #{NILCLASS_METHODS})
+keep_methods(:TrueClass, #{TRUECLASS_METHODS})
+keep_methods(:FalseClass, #{FALSECLASS_METHODS})
+keep_methods(:Enumerable, #{ENUMERABLE_METHODS})
+keep_methods(:String, #{STRING_METHODS})
+Kernel.class_eval do
+ def `(*args)
+   raise NoMethodError, "` is unavailable"
+ end
+
+ def system(*args)
+   raise NoMethodError, "system is unavailable"
+ end
+end
+
+clean_constants
+
+STRING

lib/discourse_chatbot/safe_ruby/lib/method_whitelist.rb

@@ -0,0 +1,270 @@
+IO_S_METHODS = %w[
+  new
+  foreach
+  open
+]
+
+KERNEL_S_METHODS = %w[
+  Array
+  binding
+  block_given?
+  catch
+  chomp
+  chomp!
+  chop
+  chop!
+  eval
+  fail
+  Float
+  format
+  global_variables
+  gsub
+  gsub!
+  Integer
+  iterator?
+  lambda
+  local_variables
+  loop
+  method_missing
+  proc
+  raise
+  scan
+  split
+  sprintf
+  String
+  sub
+  sub!
+  throw
+  ].freeze
+
+SYMBOL_S_METHODS = %w[
+all_symbols
+].freeze
+
+STRING_S_METHODS = %w[
+].freeze
+
+KERNEL_METHODS = %w[
+==
+
+ray
+nding
+ock_given?
+tch
+omp
+omp!
+op
+op!
+ass
+clone
+dup
+eql?
+equal?
+eval
+fail
+Float
+format
+freeze
+frozen?
+global_variables
+gsub
+gsub!
+hash
+id
+initialize_copy
+inspect
+instance_eval
+instance_of?
+instance_variables
+instance_variable_get
+instance_variable_set
+instance_variable_defined?
+Integer
+is_a?
+iterator?
+kind_of?
+lambda
+local_variables
+loop
+methods
+method_missing
+nil?
+private_methods
+print
+proc
+protected_methods
+public_methods
+raise
+remove_instance_variable
+respond_to?
+respond_to_missing?
+scan
+send
+singleton_methods
+singleton_method_added
+singleton_method_removed
+singleton_method_undefined
+split
+sprintf
+String
+sub
+sub!
+taint
+tainted?
+throw
+to_a
+to_s
+type
+untaint
+__send__
+].freeze
+
+NILCLASS_METHODS = %w[
+&
+inspect
+nil?
+to_a
+to_f
+to_i
+to_s
+^
+|
+].freeze
+
+SYMBOL_METHODS = %w[
+===
+id2name
+inspect
+to_i
+to_int
+to_s
+to_sym
+].freeze
+
+TRUECLASS_METHODS = %w[
+&
+to_s
+^
+|
+].freeze
+
+FALSECLASS_METHODS = %w[
+&
+to_s
+^
+|
+].freeze
+
+ENUMERABLE_METHODS = %w[
+all?
+any?
+collect
+detect
+each_with_index
+entries
+find
+find_all
+grep
+include?
+inject
+map
+max
+member?
+min
+partition
+reject
+select
+sort
+sort_by
+to_a
+zip
+].freeze
+
+STRING_METHODS = %w[
+%
+*
++
+<<
+<=>
+==
+=~
+capitalize
+capitalize!
+casecmp
+center
+chomp
+chomp!
+chop
+chop!
+concat
+count
+crypt
+delete
+delete!
+downcase
+downcase!
+dump
+each
+each_byte
+each_line
+empty?
+eql?
+gsub
+gsub!
+hash
+hex
+include?
+index
+initialize
+initialize_copy
+insert
+inspect
+intern
+length
+ljust
+lines
+lstrip
+lstrip!
+match
+next
+next!
+oct
+replace
+reverse
+reverse!
+rindex
+rjust
+rstrip
+rstrip!
+scan
+size
+slice
+slice!
+split
+squeeze
+squeeze!
+strip
+strip!
+start_with?
+sub
+sub!
+succ
+succ!
+sum
+swapcase
+swapcase!
+to_f
+to_i
+to_s
+to_str
+to_sym
+tr
+tr!
+tr_s
+tr_s!
+upcase
+upcase!
+upto
+[]
+[]=
+].freeze

lib/discourse_chatbot/safe_ruby/lib/safe_ruby.rb

@@ -0,0 +1,9 @@
+require 'childprocess'
+require_relative 'method_whitelist'
+require_relative 'constant_whitelist'
+require_relative 'make_safe_code'
+require_relative 'safe_ruby/runner'
+require_relative 'safe_ruby/version'
+
+class SafeRuby
+end