Module: Procemon::ObjectEXT

Defined in:
lib/procemon/eval.rb

Instance Method Summary collapse

Instance Method Details

#safe_eval(*args) ⇒ Object

safe_eval(string [, binding [, filename [,lineno]]] *allowed_class/module_names ) -> obj

Definition of the safe levels

$SAFE >= 1

The environment variables RUBYLIB and RUBYOPT are not processed, and the current directory is not added to the path.

                                                                                                               The command-line options -e, -i, -I, -r, -s, -S, and -x are not allowed.
Can't start processes from $PATH if any directory in it is world-writable.
Can't manipulate or chroot to a directory whose name is a tainted string.
                                                                                  Can't glob tainted strings.
Can't eval tainted strings.
                                                                                                                     Can't load or require a file whose name is a tainted string.
Can't manipulate or query the status of a file or pipe whose name is a tainted string.
                                                                                                                                                                                                                    Can't execute a system command or exec a program from a tainted string.
Can't pass trap a tainted string.

                                                                                                                                                                                                                                                          $SAFE >= 2

Can’t change, make, or remove directories, or use chroot.

Can't load a file from a world-writable directory.
Can't load a file from a tainted filename starting with ~.
Can't use File#chmod , File#chown , File#lstat , File.stat , File#truncate , File.umask , File#flock , IO#ioctl , IO#stat , Kernel#fork , Kernel#syscall , Kernel#trap . Process::setpgid , Process::setsid , Process::setpriority , or Process::egid= .

Can’t handle signals using trap.

$SAFE >= 3

All objects are created tainted.
Can't untaint objects.

Evaluates the Ruby expression(s) in string. If binding is given, which must be a Binding object, the evaluation is performed in its context. If the optional filename and lineno parameters are present, they will be used when reporting syntax errors.

def get_binding(str)
  return binding
end
str = "hello"
safe_eval "str + ' Fred'" ,Kernel                      #=> "hello Fred"
safe_eval "str + ' Fred'", get_binding("bye") ,Kernel  #=> "bye Fred"



46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
 
# File 'lib/procemon/eval.rb', line 46

def safe_eval(*args)

  # require 'stringio'
  # old_values = [$stderr,$VERBOSE]
  # $stderr = StringIO.new
  # $VERBOSE= false

  ::Thread.new{

    safe_ok= false
    begin
      $SAFE= 3
      safe_ok= true
    rescue
    end
    if safe_ok
      eval(*args)
    end

  }.value

# ensure
  # $stderr = old_values[0]
  # $VERBOSE= old_values[1]

end