[Python-Dev] Sandboxing Python (original) (raw)

Guido van Rossum guido at python.org
Mon Mar 5 22:47:59 CET 2012

On Mon, Mar 5, 2012 at 1:16 PM, Victor Stinner <victor.stinner at gmail.com> wrote:

2012/3/5 Serhiy Storchaka <storchaka at gmail.com>:

05.03.12 11:09, Victor Stinner написав(ла):

pysandbox uses SIGALRM with a timeout of 5 seconds by default. You can change this timeout or disable it completly.

pysandbox doesn't provide a function to limit the memory yet, you have to do it manually. It's not automatic because there is no portable way to implement such limit and it's difficult to configure it. For my IRC bot using pysandbox, setrlimit() is used with RLIMITAS. But it does not work for extensive C-calculations. sum(xrange(1000000000)) runs 2.5 minutes on my computer instead of 5 seconds, and map(sum,_ _[xrange(1000000000)] * 1000000) -- almost infinity time. pysandbox doesn't provide a reliable time limit too, it is also necessary to mention. Ah yes, I realized that SIGALRM is handled by the C signal handler, but Python only handles the signal later. sum() doesn't call PyErrCheckSignals() to check for pending signals.

Just forbid the sandboxed code from using the signal module, and set the signal to the default action (abort).

Apply the timeout would require to modify the sum() function. A more generic solution would be to use a subprocess.

Maybe it would make more sense to add such a test to xrange()? (Maybe not every iteration but every 10 or 100 iterations.)

-- --Guido van Rossum (python.org/~guido)

More information about the Python-Dev mailing list