pycapsicum

Pycapsicum is a python interface to Capsicum (sandboxing for FreeBSD). It works on FreeBSD10, but not FreeBSD9 (an earlier version supports 9)

I would recommend you understand capsicum in C before using this module, because it's not a simple system to understand.

API

::

Quick Demo:

import pycapsicum as p

# get a fileno for /tmp
t = p.opendir('/tmp', 'rw')

#enter capability mode
p.enter()

# create a new CapRights object
a = p.CapRights()

# use openat to open a file in tmp
x = p.openat(t,'foo', 'rw')

# x is a python file object
x.readlines()

# get the capabilities on x
a.get(x)

# print the capabilites out
print a.caps

# make a new CapRights, set to CAP_READ
b = p.CapRights(['CAP_READ'])

# set those capabilites to x
b.limit(x)

# get the capabilities from x
a.get(x)

# print them out. will be ['CAP_READ']
print a.caps

For details on the specific functions see the man pages for the man pages.

enter()::

Enter sandboxed mode.

sandboxed()::

Returns True if in sandboxed mode, False otherwise.

getmode()::

Like sandboxed(), but causes an exception on error.

ioctls_limit(fd, cmdlist)::

Sets ioctl limits on FD. See the manpage for cap_ioctls_limit for
more details.

fd can be a integer, python file, or python socket. Or, and object
a fileno() method

ioctls_get(fd)::

Gets ioctl limits on FD. See the manpage for cap_ioctls_get for
more details.

fd can be a integer, python file, or python socket. Or, and object
a fileno() method

fcntls_limit(fd, rights)::

Sets fcntls limits on FD. See the manpage for cap_fcntls_limit for
more details.

Possible values for right are pycapsicum.CAP_FCNTL_GETFL,
pycapsicum.CAP_FCNTL_SETFL, pycapsicum.CAP_FCNTL_GETOWN,
pycapsicum.CAP_FCNTL_SETOWN, pycapsicum.CAP_FCNTL_ALL, or any set
of flags '|'ed together

fd can be a integer, python file, or python socket. Or, and object
a fileno() method

fcntls_get(fd)::

Gets fcntls limits on FD. See the manpage for cap_fcntls_get for
more details.

fd can be a integer, python file, or python socket. Or, and object
a fileno() method

openat(fd, path, flags)::

Not strictly cap related, openat() allows you to open a file if you
have the fd (int only) of and opened directory.

'flags' is either an integer or 'r','w', or 'rw'

opendir(path, flags):

opendir() allows you to get the FD for a directory (since standard
python doesn't allow you to call open() on a directory)

'flags' is either an integer or 'r','w', or 'rw'

The CapRights() object:

class CapRights(object)::

An Object that encapsulates a cap_rights_t. Represents a set of
capabilites

__init__(self, caps=None)::

Can be called with optional list of capabilites to initialize with

caps::

A list of human readable capabilities set in the CapRights

set(self, caplist):

set a list of capabilities on the object

clear(self, caplist):

clear a list of capabilities from the object

is_set(self, caplist):

return true if the list of capabilities are set

is_valid(self):

return true if the set of capabilites are valid

merge(self, otherCR):

Merge the capabilities set in otherCR into this CapRights

remove(self, otherCR):

remove the capabilities set in otherCR from this CapRights

contains(self, otherCR):

True if this CapRights has all the capabilities in otherCR

limit(self, fd):

Set the capabilities in this CapRights onto fd (which can be an
int, file object, socket object, or any object with a fileno()
method.

get(self, fd):

Get the capabilities into this CapRights from fd (which can be an
int, file object, socket object, or any object with a fileno()
method.