Line data Source code
1 : #ifndef _LINUX_NSPROXY_H
2 : #define _LINUX_NSPROXY_H
3 :
4 : #include <linux/spinlock.h>
5 : #include <linux/sched.h>
6 :
7 : struct mnt_namespace;
8 : struct uts_namespace;
9 : struct ipc_namespace;
10 : struct pid_namespace;
11 : struct fs_struct;
12 :
13 : /*
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 : */
25 : struct nsproxy {
26 : atomic_t count;
27 : struct uts_namespace *uts_ns;
28 : struct ipc_namespace *ipc_ns;
29 : struct mnt_namespace *mnt_ns;
30 : struct pid_namespace *pid_ns;
31 : struct net *net_ns;
32 : };
33 : extern struct nsproxy init_nsproxy;
34 :
35 : /*
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 :
60 : static inline struct nsproxy *task_nsproxy(struct task_struct *tsk)
61 : {
62 : return rcu_dereference(tsk->nsproxy);
63 : }
64 :
65 : int copy_namespaces(unsigned long flags, struct task_struct *tsk);
66 : void exit_task_namespaces(struct task_struct *tsk);
67 : void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new);
68 : void free_nsproxy(struct nsproxy *ns);
69 : int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **,
70 : struct fs_struct *);
71 :
72 : static inline void put_nsproxy(struct nsproxy *ns)
73 : {
74 : if (atomic_dec_and_test(&ns->count)) {
75 : free_nsproxy(ns);
76 : }
77 : }
78 :
79 : static inline void get_nsproxy(struct nsproxy *ns)
80 : {
81 : atomic_inc(&ns->count);
82 : }
83 :
84 : #ifdef CONFIG_CGROUP_NS
85 : int ns_cgroup_clone(struct task_struct *tsk, struct pid *pid);
86 : #else
87 : static inline int ns_cgroup_clone(struct task_struct *tsk, struct pid *pid)
88 : {
89 : return 0;
90 : }
91 1 : #endif
92 :
93 : #endif
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