clone process support in python

python

Solution

Well, finally I think I got the answer, is just usign ctypes with libc,

This is a simple proof of concept:

from ctypes import *

libc = CDLL("libc.so.6")

# Create stack.                                                                                                                                                                            
stack = c_char_p(" " * 8096)

def f():
    print libc.getpid()
    return 0

# Conver function to c type returning an integer.                                                                                                                                          
f_c = CFUNCTYPE(c_int)(f)

# We need the top of the stack.                                                                                                                                                            
stack_top = c_void_p(cast(stack, c_void_p).value + 8096)

# Call clone with the NEWPID Flag                                                                                                                                                          
libc.clone(f_c, stack_top, 0x20000000)

This has to be run by root.

Problem

Is there any support of the syscall `clone(2)` (not `os.fork`) in Python? I want to play with Linux namespaces under Python but it seems that there is not a lot of information about it. Edits: I think ctypes with libc is the answer but I'm still not having any success. fork works without problems since it doesn't have any argument then this code work: ``` from ctypes import * libc = CDLL("libc.so.6") libc.fork() ``` With clone I'm trying this: ``` from ctypes import * def f(): print "In callback." return 0 libc = CDLL("libc.so.6") f_c = CFUNCTYPE(c_int)(f) print libc.getpid() print libc.clone(f_c) print get_errno() ``` Clone actually has this signature: int clone(int (*fn)(void *), void *child_stack, int flags, void arg, ... / pid_t *ptid, struct user_desc *tls, pid_t *ctid */ ); I still need to pass *child_stack and flags but have no idea how to do it. Any help? More Edits: I got this now: ``` from ctypes import * def f(): print "In callback." return 0 libc = CDLL("libc.so.6") f_c = CFUNCTYPE(c_int)(f) stack = c_char_p(" " * 1024 * 1024) libc.clone(f_c, c_void_p(cast(stack, c_void_p).value + 1024 * 1024), 0) ``` This actually works but I imagine I making a big hole in my system with the stack, there is a cleaner way to do this? Edits: Almost done, adding the correct flag for newpid: ``` from ctypes import * libc = CDLL("libc.so.6") def f(): print libc.getpid() return 0 f_c = CFUNCTYPE(c_int)(f) stack = c_char_p(" " * 1024 * 1024) libc.clone(f_c, c_void_p(cast(stack, c_void_p).value + 1024 * 1024), 0x20000000) ``` This is not runnable just for root, and print a nice 1. And following this post the stack seems to be fine: http://code.google.com/p/chromium/wiki/LinuxPidNamespaceSupport

Original source