Restricted Execution on the cheap

[Duncan Booth]

David Pokorny wrote:

> Suppose that one wants to set up a machine to accept python code from,
> say, arbitrary email, and run it safely. Would the following
> (somewhat draconian) precautions be sufficient?
> [assume the Python code is in hack.py]
> 
> grep exec    hack.py ==> nothing
> grep eval    hack.py ==> nothing
> etc... for 'import', 'builtin', 'globals','reload'
> 'compile', 'file', 'open', 'input', 'locals', 'vars'
> 

Assuming you think *very* hard about everything that someone might try. 

Your list above certainly isn't enough though. I'm pretty sure you also 
need to block getattr otherwise:

>>> def f(): pass
>>> getattr(getattr(f, 
'shap_tybonyf'.decode('rot13'))['__ohvygvaf__'.decode('rot13')], 
'x\x9cK\xce\xcf-\xc8\xccI\x05\x00\x0b\xaf\x02\xea'.decode('zip'))
<built-in function compile>