Network namespaces tool

Network namespaces tool

[Sargun Dhillon]

I'm getting an error when I try to compile the netunshare tool.
Do you have any ideas to the error:

netunshare.c:50: error: conflicting types for 'unshare'
/usr/include/bits/sched.h:78: error: previous declaration of 'unshare' was here

Additionally, are there any plans to merge in sysfs support into the kernel?

Re: Network namespaces tool

[Benjamin Thery]

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Sargun Dhillon wrote:
> I'm getting an error when I try to compile the netunshare tool.
> Do you have any ideas to the error:
> 
> netunshare.c:50: error: conflicting types for 'unshare'
> /usr/include/bits/sched.h:78: error: previous declaration of 'unshare' was here

are you using the netunshare.c found there
http://lxc.sourceforge.net/tools/netunshare.c
?

I'm not sure it's up-to-date.
If that's the case, here is an quickly-updated version which shold work 
better for you.

Build it with: gcc -o netunshare -DHAVE_UNSHARE netunshare.c


Also, if you want to play with network namespaces (and containers), you
can try Daniel's excellent liblxc 
(http://sourceforge.net/project/showfiles.php?group_id=163076).

> Additionally, are there any plans to merge in sysfs support into the kernel?

This is a question for Eric I guess.
I don't know what are his plan with the sysfs issue. There are some
stuff to fix in sysfs first, and I don't know if there have been any
progress on this front yet.


Benjamin




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-- 
B e n j a m i n   T h e r y  - BULL/DT/Open Software R&D

    http://www.bull.com

[-- Attachment #2: netunshare.c --]
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#include <stdio.h>
#include <stdlib.h>
#include <sched.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <libgen.h>

#include <linux/unistd.h>

#ifndef _syscall0
#define _syscall0(type,name) \
type name(void) \
{\
        return syscall(__NR_##name);\
}
#endif

#ifndef _syscall1
#define _syscall1(type,name,type1,arg1) \
type name(type1 arg1) \
{\
        return syscall(__NR_##name, arg1);\
}
#endif

#ifndef HAVE_UNSHARE

#if __i386__
#    define __NR_unshare 310
#elif __x86_64__
#    define __NR_unshare 272
#elif __ia64__
#    define __NR_unshare 1296
#elif __s390x__
#    define __NR_unshare 303
#elif __powerpc__
#    define __NR_unshare 282
#else
#    error "Architecture not supported"
#endif

#ifndef unshare
static inline _syscall1 (int,  unshare, unsigned long, flags)
#endif

#endif /* HAVE_UNSHARE */

#ifndef CLONE_NEWNET
#define CLONE_NEWNET		0x40000000
#endif

static const char* procname;

static void usage(const char *name)
{
	printf("usage: %s [-h] [command [arg ...]]\n", name);
	printf("\n");
	printf("  -h		this message\n");
	printf("\n");
	exit(1);
}

int main(int argc, char *argv[])
{	
	int c;
	unsigned long flags = CLONE_NEWNET;

	procname = basename(argv[0]);

	while ((c = getopt(argc, argv, "+muiUnNphI:")) != EOF) {
		switch (c) {
		case 'h':
		default:
			usage(procname);
		}
	};
    
	argv = &argv[optind];
	argc = argc - optind;	
	
	if (unshare(flags) == -1) {
		perror("unshare");
		return 1;
	} 
	
	if (argc) {
		execve(argv[0], argv, __environ);
		perror("execve");
		return 1;
	}

	return 0;
}


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Re: Network namespaces tool

[Daniel Lezcano]

Sargun Dhillon wrote:
> I'm getting an error when I try to compile the netunshare tool.
> Do you have any ideas to the error:
>
> netunshare.c:50: error: conflicting types for 'unshare'
> /usr/include/bits/sched.h:78: error: previous declaration of 'unshare' was here
>   

There is the lxc tools at:

http://sourceforge.net/projects/lxc/

In these tools there is the lxc-unshare allowing you to do the same.
    lxc-unshare -n /bin/bash

If you find some problems with it, feel free to ask :)
I will release a new lxc-0.5.1, version fixing a few bugs very soon.
> Additionally, are there any plans to merge in sysfs support into the kernel?
>   
The sysfs patchset has been rejected and the sysfs itself should be 
reworked before submitting the sysfs per namespace. This is a long work, 
Eric can probably say more on that.
In the meantime, a patch to make netns and sysfs to co-exist has been 
pushed upstream, so we can create a network namespace without sysfs 
virtualization. This modification will be available for 2.6.29. Until 
this version is released, you can use the netdev development tree 
available at:

git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6.git

Thanks.
  -- Daniel