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tag: v2.6.20-rc1
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/*
* Copyright (C) 2006 IBM Corporation
*
* Author: Serge Hallyn <serue@us.ibm.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation, version 2 of the
* License.
*
* Jun 2006 - namespaces support
* OpenVZ, SWsoft Inc.
* Pavel Emelianov <xemul@openvz.org>
*/

#include <linux/module.h>
#include <linux/version.h>
#include <linux/nsproxy.h>
#include <linux/init_task.h>
#include <linux/mnt_namespace.h>
#include <linux/utsname.h>
#include <linux/pid_namespace.h>

struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);

static inline void get_nsproxy(struct nsproxy *ns)
{
atomic_inc(&ns->count);
}

void get_task_namespaces(struct task_struct *tsk)
{
struct nsproxy *ns = tsk->nsproxy;
if (ns) {
get_nsproxy(ns);
}
}

/*
* creates a copy of "orig" with refcount 1.
* This does not grab references to the contained namespaces,
* so that needs to be done by dup_namespaces.
*/
static inline struct nsproxy *clone_namespaces(struct nsproxy *orig)
{
struct nsproxy *ns;

ns = kmemdup(orig, sizeof(struct nsproxy), GFP_KERNEL);
if (ns)
atomic_set(&ns->count, 1);
return ns;
}

/*
* copies the nsproxy, setting refcount to 1, and grabbing a
* reference to all contained namespaces. Called from
* sys_unshare()
*/
struct nsproxy *dup_namespaces(struct nsproxy *orig)
{
struct nsproxy *ns = clone_namespaces(orig);

if (ns) {
if (ns->mnt_ns)
get_mnt_ns(ns->mnt_ns);
if (ns->uts_ns)
get_uts_ns(ns->uts_ns);
if (ns->ipc_ns)
get_ipc_ns(ns->ipc_ns);
if (ns->pid_ns)
get_pid_ns(ns->pid_ns);
}

return ns;
}

/*
* called from clone. This now handles copy for nsproxy and all
* namespaces therein.
*/
int copy_namespaces(int flags, struct task_struct *tsk)
{
struct nsproxy *old_ns = tsk->nsproxy;
struct nsproxy *new_ns;
int err = 0;

if (!old_ns)
return 0;

get_nsproxy(old_ns);

if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC)))
return 0;

new_ns = clone_namespaces(old_ns);
if (!new_ns) {
err = -ENOMEM;
goto out;
}

tsk->nsproxy = new_ns;

err = copy_mnt_ns(flags, tsk);
if (err)
goto out_ns;

err = copy_utsname(flags, tsk);
if (err)
goto out_uts;

err = copy_ipcs(flags, tsk);
if (err)
goto out_ipc;

err = copy_pid_ns(flags, tsk);
if (err)
goto out_pid;

out:
put_nsproxy(old_ns);
return err;

out_pid:
if (new_ns->ipc_ns)
put_ipc_ns(new_ns->ipc_ns);
out_ipc:
if (new_ns->uts_ns)
put_uts_ns(new_ns->uts_ns);
out_uts:
if (new_ns->mnt_ns)
put_mnt_ns(new_ns->mnt_ns);
out_ns:
tsk->nsproxy = old_ns;
kfree(new_ns);
goto out;
}

void free_nsproxy(struct nsproxy *ns)
{
if (ns->mnt_ns)
put_mnt_ns(ns->mnt_ns);
if (ns->uts_ns)
put_uts_ns(ns->uts_ns);
if (ns->ipc_ns)
put_ipc_ns(ns->ipc_ns);
if (ns->pid_ns)
put_pid_ns(ns->pid_ns);
kfree(ns);
}
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