aboutsummaryrefslogtreecommitdiffstats
path: root/include/linux/nsproxy.h
blob: 10e5947491c7b9b54f423ab567f9948be021eb6f (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
#ifndef _LINUX_NSPROXY_H
#define _LINUX_NSPROXY_H

#include <linux/spinlock.h>
#include <linux/sched.h>

struct mnt_namespace;
struct uts_namespace;
struct ipc_namespace;
struct pid_namespace;
struct fs_struct;

/*
 * A structure to contain pointers to all per-process
 * namespaces - fs (mount), uts, network, sysvipc, etc.
 *
 * 'count' is the number of tasks holding a reference.
 * The count for each namespace, then, will be the number
 * of nsproxies pointing to it, not the number of tasks.
 *
 * The nsproxy is shared by tasks which share all namespaces.
 * As soon as a single namespace is cloned or unshared, the
 * nsproxy is copied.
 */
struct nsproxy {
	atomic_t count;
	struct uts_namespace *uts_ns;
	struct ipc_namespace *ipc_ns;
	struct mnt_namespace *mnt_ns;
	struct pid_namespace *pid_ns;
	struct net 	     *net_ns;
};
extern struct nsproxy init_nsproxy;

/*
 * the namespaces access rules are:
 *
 *  1. only current task is allowed to change tsk->nsproxy pointer or
 *     any pointer on the nsproxy itself
 *
 *  2. when accessing (i.e. reading) current task's namespaces - no
 *     precautions should be taken - just dereference the pointers
 *
 *  3. the access to other task namespaces is performed like this
 *     rcu_read_lock();
 *     nsproxy = task_nsproxy(tsk);
 *     if (nsproxy != NULL) {
 *             / *
 *               * work with the namespaces here
 *               * e.g. get the reference on one of them
 *               * /
 *     } / *
 *         * NULL task_nsproxy() means that this task is
 *         * almost dead (zombie)
 *         * /
 *     rcu_read_unlock();
 *
 */

static inline struct nsproxy *task_nsproxy(struct task_struct *tsk)
{
	return rcu_dereference(tsk->nsproxy);
}

int copy_namespaces(unsigned long flags, struct task_struct *tsk);
void exit_task_namespaces(struct task_struct *tsk);
void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new);
void free_nsproxy(struct nsproxy *ns);
int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **,
	struct cred *, struct fs_struct *);
int __init nsproxy_cache_init(void);

static inline void put_nsproxy(struct nsproxy *ns)
{
	if (atomic_dec_and_test(&ns->count)) {
		free_nsproxy(ns);
	}
}

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

#endif