Secure execution of Code
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Denis Knauf 5c52ea2ab1 test-units added - does not work, but only in unit-tests it does not work. exception if somebody tries to use it in rubinius 12 years ago
bin test-units added - does not work, but only in unit-tests it does not work. exception if somebody tries to use it in rubinius 12 years ago
lib test-units added - does not work, but only in unit-tests it does not work. exception if somebody tries to use it in rubinius 12 years ago
test test-units added - does not work, but only in unit-tests it does not work. exception if somebody tries to use it in rubinius 12 years ago
AUTHORS first commit 12 years ago
LICENSE first commit 12 years ago
README.md VERSION 0.0.2 12 years ago
Rakefile little changes: metafiles 12 years ago
VERSION VERSION 0.0.2 12 years ago

README.md

Requires

Ruby MRI or Ruby 1.9.

Will not work with Rubinius! It does not support $SAFE.

I do not know JRuby.

Install

gem install Safebox

Usage

First load the safebox:

require 'safebox'

The most things in your Safebox are possible:

value = Safebox.eval "1+2**9"  # => 513
value = Safebox.eval {|| 1+2**8 }  # => 257

You can use a String or a Proc, also as argument:

value = Safebox.eval lambda {|| 1+2**7 }

More complex code with classes and everything else...

value = Safebox.eval do
	class Mail
		attr_accessor :subject, :body, :to, :from
		def generate
			[ "To: #{@to}", "From: #{@from}",
				"Subject: #{@subject}", '', @body ].join "\n"
		end
	end
	mail = Mail.new
	mail.from, mail.to, mail.subject = "me", "root", "Plz install Ruby :)"
	mail.subject = "..."
	mail.generate
end

Only some good things are not possible:

Safebox.eval "$stdout.puts 'I am OK!'"  # not possible :(

But, very bad code will not damage your system.

Safebox.eval "class Unsecure;def self.code() system 'rm *' ; end end; Unsecure.code"  # will fail :)

This will raise a SecurityError.

What is with raised exceptions, like SecurityError or others?

Safebox.eval "raise Exception"

This will print the Exception to Console.

You want to get the Exception?

ret = Safebox.run "raise Exception"
ret # => [:exception, #<Exception>]

What is Safebox.run?

ret = Safebox.run "1+2**9"
ret # => [:value, 513]

It returns the value or the raised exception. -- Nothing else.

You should know, Ruby is not stupid. I am very surprised, because this is not possible:

aA = Safebox.eval do
	class A
		def to_s
			'Owned!'
		end
	end
	A.new
end
aA.to_s  # => SecurityError: calling insecure method: to_s

A#to_s is defined in our Safebox, so every call outside can be a security hole.

But you can use #to_s in an other Safebox, withour any risk:

Safebox.eval aA.method( :to_s)  # => "Owned!"  # Not really :)

Behind Safebox

It uses only a Thread, $SAFE=4 and some code for automatism.

The real magic is Ruby itself.