linux/kernel/nsproxy.c at master · microinfo/linux · GitHub

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* 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/export.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;

}

int __init nsproxy_cache_init(void)

{

nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);

return 0;

}

linux/kernel/nsproxy.c at master · microinfo/linux · GitHub

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