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tag: v3.0-rc7
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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/slab.h>
#include <linux/module.h>
#include <linux/nsproxy.h>
#include <linux/init_task.h>
#include <linux/mnt_namespace.h>
#include <linux/utsname.h>
#include <linux/pid_namespace.h>
#include <net/net_namespace.h>
#include <linux/ipc_namespace.h>
#include <linux/proc_fs.h>
#include <linux/file.h>
#include <linux/syscalls.h>

static struct kmem_cache *nsproxy_cachep;

struct nsproxy init_nsproxy = {
.count = ATOMIC_INIT(1),
.uts_ns = &init_uts_ns,
#if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC)
.ipc_ns = &init_ipc_ns,
#endif
.mnt_ns = NULL,
.pid_ns = &init_pid_ns,
#ifdef CONFIG_NET
.net_ns = &init_net,
#endif
};

static inline struct nsproxy *create_nsproxy(void)
{
struct nsproxy *nsproxy;

nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL);
if (nsproxy)
atomic_set(&nsproxy->count, 1);
return nsproxy;
}

/*
* Create new nsproxy and all of its the associated namespaces.
* Return the newly created nsproxy. Do not attach this to the task,
* leave it to the caller to do proper locking and attach it to task.
*/
static struct nsproxy *create_new_namespaces(unsigned long flags,
struct task_struct *tsk, struct fs_struct *new_fs)
{
struct nsproxy *new_nsp;
int err;

new_nsp = create_nsproxy();
if (!new_nsp)
return ERR_PTR(-ENOMEM);

new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, new_fs);
if (IS_ERR(new_nsp->mnt_ns)) {
err = PTR_ERR(new_nsp->mnt_ns);
goto out_ns;
}

new_nsp->uts_ns = copy_utsname(flags, tsk);
if (IS_ERR(new_nsp->uts_ns)) {
err = PTR_ERR(new_nsp->uts_ns);
goto out_uts;
}

new_nsp->ipc_ns = copy_ipcs(flags, tsk);
if (IS_ERR(new_nsp->ipc_ns)) {
err = PTR_ERR(new_nsp->ipc_ns);
goto out_ipc;
}

new_nsp->pid_ns = copy_pid_ns(flags, task_active_pid_ns(tsk));
if (IS_ERR(new_nsp->pid_ns)) {
err = PTR_ERR(new_nsp->pid_ns);
goto out_pid;
}

new_nsp->net_ns = copy_net_ns(flags, tsk->nsproxy->net_ns);
if (IS_ERR(new_nsp->net_ns)) {
err = PTR_ERR(new_nsp->net_ns);
goto out_net;
}

return new_nsp;

out_net:
if (new_nsp->pid_ns)
put_pid_ns(new_nsp->pid_ns);
out_pid:
if (new_nsp->ipc_ns)
put_ipc_ns(new_nsp->ipc_ns);
out_ipc:
if (new_nsp->uts_ns)
put_uts_ns(new_nsp->uts_ns);
out_uts:
if (new_nsp->mnt_ns)
put_mnt_ns(new_nsp->mnt_ns);
out_ns:
kmem_cache_free(nsproxy_cachep, new_nsp);
return ERR_PTR(err);
}

/*
* called from clone. This now handles copy for nsproxy and all
* namespaces therein.
*/
int copy_namespaces(unsigned long 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 |
CLONE_NEWPID | CLONE_NEWNET)))
return 0;

if (!capable(CAP_SYS_ADMIN)) {
err = -EPERM;
goto out;
}

/*
* CLONE_NEWIPC must detach from the undolist: after switching
* to a new ipc namespace, the semaphore arrays from the old
* namespace are unreachable. In clone parlance, CLONE_SYSVSEM
* means share undolist with parent, so we must forbid using
* it along with CLONE_NEWIPC.
*/
if ((flags & CLONE_NEWIPC) && (flags & CLONE_SYSVSEM)) {
err = -EINVAL;
goto out;
}

new_ns = create_new_namespaces(flags, tsk, tsk->fs);
if (IS_ERR(new_ns)) {
err = PTR_ERR(new_ns);
goto out;
}

tsk->nsproxy = new_ns;

out:
put_nsproxy(old_ns);
return err;
}

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);
put_net(ns->net_ns);
kmem_cache_free(nsproxy_cachep, ns);
}

/*
* Called from unshare. Unshare all the namespaces part of nsproxy.
* On success, returns the new nsproxy.
*/
int unshare_nsproxy_namespaces(unsigned long unshare_flags,
struct nsproxy **new_nsp, struct fs_struct *new_fs)
{
int err = 0;

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

if (!capable(CAP_SYS_ADMIN))
return -EPERM;

*new_nsp = create_new_namespaces(unshare_flags, current,
new_fs ? new_fs : current->fs);
if (IS_ERR(*new_nsp)) {
err = PTR_ERR(*new_nsp);
goto out;
}

out:
return err;
}

void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
{
struct nsproxy *ns;

might_sleep();

ns = p->nsproxy;

rcu_assign_pointer(p->nsproxy, new);

if (ns && atomic_dec_and_test(&ns->count)) {
/*
* wait for others to get what they want from this nsproxy.
*
* cannot release this nsproxy via the call_rcu() since
* put_mnt_ns() will want to sleep
*/
synchronize_rcu();
free_nsproxy(ns);
}
}

void exit_task_namespaces(struct task_struct *p)
{
switch_task_namespaces(p, NULL);
}

SYSCALL_DEFINE2(setns, int, fd, int, nstype)
{
const struct proc_ns_operations *ops;
struct task_struct *tsk = current;
struct nsproxy *new_nsproxy;
struct proc_inode *ei;
struct file *file;
int err;

if (!capable(CAP_SYS_ADMIN))
return -EPERM;

file = proc_ns_fget(fd);
if (IS_ERR(file))
return PTR_ERR(file);

err = -EINVAL;
ei = PROC_I(file->f_dentry->d_inode);
ops = ei->ns_ops;
if (nstype && (ops->type != nstype))
goto out;

new_nsproxy = create_new_namespaces(0, tsk, tsk->fs);
if (IS_ERR(new_nsproxy)) {
err = PTR_ERR(new_nsproxy);
goto out;
}

err = ops->install(new_nsproxy, ei->ns);
if (err) {
free_nsproxy(new_nsproxy);
goto out;
}
switch_task_namespaces(tsk, new_nsproxy);
out:
fput(file);
return err;
}

static int __init nsproxy_cache_init(void)
{
nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
return 0;
}

module_init(nsproxy_cache_init);
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