Metadata-Version: 1.1
Name: boxed
Version: 0.2.0
Summary: Simple and lightweight sandbox solution for Python an Linux.
Home-page: UNKNOWN
Author: Fábio Macêdo Mendes
Author-email: fabiomacedomendes@gmail.com
License: UNKNOWN
Description: Boxed is a simple sandboxing solution to Python. It works by running arbitrary
        Python functions as an unprivileged user. It relies on the builtin Linux Kernel
        security, which is very good.
        
        The API is very simple::
        
            from boxed import run
        
            result = run(target_func, args=args, kwargs=kwargs)
        
        This will spawn a Python interpreted that drops its privileges and runs
        ``target_func(*args, **kwds)`` as the **nobody** user. Communication
        between the master and slave processes can is carried by serialized streams
        which can use pickle, cloudpickle, dill or JSON.
        
        There is a possible vulnerability if the target function outputs a
        picklable object that produces malicious side-effects when unpickled. We don't
        know how to exploit this possibility, but it is theoretically possible. It is
        probably not even hard to exploit using dill or cloudpickle as the serializers
        since both can pickle functions by bytecode, opening many doors for attack.
        
        The possibility of damage is greatly reduced by using a JSON serializer. The
        downside is that both the inputs and the outputs of the target function must
        be serializable as JSON. Besides that, the target function itself must be a
        Python callable living in a public namespace: the JSON serializer just sends the
        function qualified name to the sandbox. In order to use the JSON serializer,
        just pass the serializer='json' argument::
        
            >>> from boxed import run
            >>> from math import sqrt
            >>> run(sqrt, args=(4,), serializer='json')
            2.0
        
        
        How does it work?
        =================
        
        The sandbox is spawned by in a different Python interpreter called python_setuid
        which is created on installation. This is just a copy of the regular interpreter
        with the Linux SETUID capability enabled. This simple technique allows the
        executable to change its UID, which enable it to drop its privileges early
        during the sandbox execution.
        
        This might remember the infaous SUID bit. SUID executables allows an user spawn
        program to start its life with super user permissions and (hopefully) to drop
        them as soon as possible while keeping only the permissions necessary for the
        program to run. The classical example is a webserver. Only the super user can
        listen to port 80 (or the other lower ports), thus the webserver must start its
        life as root and quickly drop all privileges but that of communicating in the
        desired ports.
        
        Linux capabilities are a fine-grained version of the SUID bit. We can grant
        very specific privileges to any file. The boxed library uses a Python
        interpreter with the SETUID capability which grant us only the
        capability of changing the UID of a process. Even if the process escalates its
        privileges to run as UID=0 (the super user), none of the other permissions are
        granted so it will not gain super user powers. In particular, it will not be
        able to read, write or execute any file that the original user who executed
        the sandbox did not have access to.
        
        By default, boxed runs the sandbox as the `nobody` user. Upon installation,
        we create a copy of the interpreter called /usr/bin/python_boxed and then
        apply the command::
        
            $ setcap cap_setuid+ep /usr/bin/python_boxed
        
        
        Does it work on Windows, OSX, BSD, etc?
        =======================================
        
        No. This technique is linux-specific. Also, it is very difficult to provide a good,
        lightweight, and crossplatform sandboxing solution. Currently we have no plans
        to implement sandboxing in other platforms.
Platform: any
Classifier: Development Status :: 4 - Beta
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: GNU General Public License (GPL)
Classifier: Operating System :: POSIX :: Linux
Classifier: Programming Language :: Python :: 3 :: Only
Classifier: Topic :: Software Development :: Libraries
