Linux kernel mirror (for testing)
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linux
1#ifndef _LINUX_NSPROXY_H
2#define _LINUX_NSPROXY_H
3
4#include <linux/spinlock.h>
5#include <linux/sched.h>
6
7struct mnt_namespace;
8struct uts_namespace;
9struct ipc_namespace;
10struct pid_namespace;
11struct fs_struct;
12
13/*
14 * A structure to contain pointers to all per-process
15 * namespaces - fs (mount), uts, network, sysvipc, etc.
16 *
17 * The pid namespace is an exception -- it's accessed using
18 * task_active_pid_ns. The pid namespace here is the
19 * namespace that children will use.
20 *
21 * 'count' is the number of tasks holding a reference.
22 * The count for each namespace, then, will be the number
23 * of nsproxies pointing to it, not the number of tasks.
24 *
25 * The nsproxy is shared by tasks which share all namespaces.
26 * As soon as a single namespace is cloned or unshared, the
27 * nsproxy is copied.
28 */
29struct nsproxy {
30 atomic_t count;
31 struct uts_namespace *uts_ns;
32 struct ipc_namespace *ipc_ns;
33 struct mnt_namespace *mnt_ns;
34 struct pid_namespace *pid_ns_for_children;
35 struct net *net_ns;
36};
37extern struct nsproxy init_nsproxy;
38
39/*
40 * the namespaces access rules are:
41 *
42 * 1. only current task is allowed to change tsk->nsproxy pointer or
43 * any pointer on the nsproxy itself
44 *
45 * 2. when accessing (i.e. reading) current task's namespaces - no
46 * precautions should be taken - just dereference the pointers
47 *
48 * 3. the access to other task namespaces is performed like this
49 * rcu_read_lock();
50 * nsproxy = task_nsproxy(tsk);
51 * if (nsproxy != NULL) {
52 * / *
53 * * work with the namespaces here
54 * * e.g. get the reference on one of them
55 * * /
56 * } / *
57 * * NULL task_nsproxy() means that this task is
58 * * almost dead (zombie)
59 * * /
60 * rcu_read_unlock();
61 *
62 */
63
64static inline struct nsproxy *task_nsproxy(struct task_struct *tsk)
65{
66 return rcu_dereference(tsk->nsproxy);
67}
68
69int copy_namespaces(unsigned long flags, struct task_struct *tsk);
70void exit_task_namespaces(struct task_struct *tsk);
71void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new);
72void free_nsproxy(struct nsproxy *ns);
73int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **,
74 struct cred *, struct fs_struct *);
75int __init nsproxy_cache_init(void);
76
77static inline void put_nsproxy(struct nsproxy *ns)
78{
79 if (atomic_dec_and_test(&ns->count)) {
80 free_nsproxy(ns);
81 }
82}
83
84static inline void get_nsproxy(struct nsproxy *ns)
85{
86 atomic_inc(&ns->count);
87}
88
89#endif