How to safely let users run arbitrary Ruby code?

I realize this sounds a little crazy, but I'm working on a project for which I need a server to run user-provided Ruby code and return the result.

I'm looking to prevent something like this:

system("rm -rf /")
eval("something_evil")
# etc...

I'm sure there must be some reasonably safe way to do this, as it already exists at places like tryruby.org. Any help is greatly appreciated, tha开发者_如何学Gonks!

Three suggestions:

1) Take a look at Ruby taint levels. This provides some degree of protection against, eval('evil_code') type things, etc.

2) Unless user's actually need access to the local file system, use something like fakefs

3) No matter what else you do follow Tronic's suggestion (can be a pain to setup, but limited chroot jails are about the only way to make absolutely sure that user's cannot access resources you don't explicitly want them to).

Run the program ptraced with a whitelist of allowed syscalls, as user/group nobody, with resource limits (memory usage etc), in a minimal chroot.

A "blank slate" is an object stripped of (most of) its methods. A "clean room" is an object within which you evaluate potentially unsafe room. If you evaluate the code in a "clean room" which is also a "blank slate," cranking the safe level up as high as it will go, you will afford yourself a great deal of protection. Nothing in security is sure, so this should be considered a layer in your security, not necessarily the only layer.

This answer shows how to do it.

I had the same problem but then came across eval.so and decided to write an API wrapper for it, called Sandie. It's as easy as:

sandie = Sandie.new(language: 'ruby')
# => #<Sandie:0x00000002e30650>
sandie.evaluate(code: 'puts "hello world"')
# => {"stdout"=>"hello world\n", "stderr"=>"", "wallTime"=>487, "exitCode"=>0}

It also supports a whole lot of other languages as well like C#, Perl, Lua, and Java.