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Serge E. Hallynab516012006-10-02 02:18:06 -07001#ifndef _LINUX_NSPROXY_H
2#define _LINUX_NSPROXY_H
3
4#include <linux/spinlock.h>
5#include <linux/sched.h>
6
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08007struct mnt_namespace;
Serge E. Hallyn4865ecf2006-10-02 02:18:14 -07008struct uts_namespace;
Kirill Korotaev25b21cb2006-10-02 02:18:19 -07009struct ipc_namespace;
Cedric Le Goater9a575a92006-12-08 02:37:59 -080010struct pid_namespace;
Al Viro5ad4e532009-03-29 19:50:06 -040011struct fs_struct;
Serge E. Hallyn1651e142006-10-02 02:18:08 -070012
Serge E. Hallynab516012006-10-02 02:18:06 -070013/*
14 * A structure to contain pointers to all per-process
15 * namespaces - fs (mount), uts, network, sysvipc, etc.
16 *
17 * 'count' is the number of tasks holding a reference.
18 * The count for each namespace, then, will be the number
19 * of nsproxies pointing to it, not the number of tasks.
20 *
21 * The nsproxy is shared by tasks which share all namespaces.
22 * As soon as a single namespace is cloned or unshared, the
23 * nsproxy is copied.
24 */
25struct nsproxy {
26 atomic_t count;
Serge E. Hallyn4865ecf2006-10-02 02:18:14 -070027 struct uts_namespace *uts_ns;
Kirill Korotaev25b21cb2006-10-02 02:18:19 -070028 struct ipc_namespace *ipc_ns;
Kirill Korotaev6b3286e2006-12-08 02:37:56 -080029 struct mnt_namespace *mnt_ns;
Cedric Le Goater9a575a92006-12-08 02:37:59 -080030 struct pid_namespace *pid_ns;
Eric W. Biederman772698f2007-09-12 11:55:17 +020031 struct net *net_ns;
Serge E. Hallynab516012006-10-02 02:18:06 -070032};
33extern struct nsproxy init_nsproxy;
34
Pavel Emelyanovcf7b7082007-10-18 23:39:54 -070035/*
36 * the namespaces access rules are:
37 *
38 * 1. only current task is allowed to change tsk->nsproxy pointer or
39 * any pointer on the nsproxy itself
40 *
41 * 2. when accessing (i.e. reading) current task's namespaces - no
42 * precautions should be taken - just dereference the pointers
43 *
44 * 3. the access to other task namespaces is performed like this
45 * rcu_read_lock();
46 * nsproxy = task_nsproxy(tsk);
47 * if (nsproxy != NULL) {
48 * / *
49 * * work with the namespaces here
50 * * e.g. get the reference on one of them
51 * * /
52 * } / *
53 * * NULL task_nsproxy() means that this task is
54 * * almost dead (zombie)
55 * * /
56 * rcu_read_unlock();
57 *
58 */
59
60static inline struct nsproxy *task_nsproxy(struct task_struct *tsk)
61{
62 return rcu_dereference(tsk->nsproxy);
63}
64
Eric W. Biederman213dd262007-07-15 23:41:15 -070065int copy_namespaces(unsigned long flags, struct task_struct *tsk);
Pavel Emelyanovcf7b7082007-10-18 23:39:54 -070066void exit_task_namespaces(struct task_struct *tsk);
67void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new);
Serge E. Hallynab516012006-10-02 02:18:06 -070068void free_nsproxy(struct nsproxy *ns);
Badari Pulavartye3222c42007-05-08 00:25:21 -070069int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **,
70 struct fs_struct *);
Serge E. Hallynab516012006-10-02 02:18:06 -070071
Linus Torvalds444f3782007-01-30 13:35:18 -080072static inline void put_nsproxy(struct nsproxy *ns)
Serge E. Hallynab516012006-10-02 02:18:06 -070073{
Linus Torvalds444f3782007-01-30 13:35:18 -080074 if (atomic_dec_and_test(&ns->count)) {
Serge E. Hallynab516012006-10-02 02:18:06 -070075 free_nsproxy(ns);
Linus Torvalds444f3782007-01-30 13:35:18 -080076 }
Serge E. Hallynab516012006-10-02 02:18:06 -070077}
78
Pavel Emelyanovcf7b7082007-10-18 23:39:54 -070079static inline void get_nsproxy(struct nsproxy *ns)
Serge E. Hallynab516012006-10-02 02:18:06 -070080{
Pavel Emelyanovcf7b7082007-10-18 23:39:54 -070081 atomic_inc(&ns->count);
Serge E. Hallynab516012006-10-02 02:18:06 -070082}
Serge E. Hallyn858d72e2007-10-18 23:39:45 -070083
Serge E. Hallynab516012006-10-02 02:18:06 -070084#endif