1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | #ifndef _LINUX_NSPROXY_H |
3 | #define _LINUX_NSPROXY_H |
4 | |
5 | #include <linux/spinlock.h> |
6 | #include <linux/sched.h> |
7 | |
8 | struct mnt_namespace; |
9 | struct uts_namespace; |
10 | struct ipc_namespace; |
11 | struct pid_namespace; |
12 | struct cgroup_namespace; |
13 | struct fs_struct; |
14 | |
15 | /* |
16 | * A structure to contain pointers to all per-process |
17 | * namespaces - fs (mount), uts, network, sysvipc, etc. |
18 | * |
19 | * The pid namespace is an exception -- it's accessed using |
20 | * task_active_pid_ns. The pid namespace here is the |
21 | * namespace that children will use. |
22 | * |
23 | * 'count' is the number of tasks holding a reference. |
24 | * The count for each namespace, then, will be the number |
25 | * of nsproxies pointing to it, not the number of tasks. |
26 | * |
27 | * The nsproxy is shared by tasks which share all namespaces. |
28 | * As soon as a single namespace is cloned or unshared, the |
29 | * nsproxy is copied. |
30 | */ |
31 | struct nsproxy { |
32 | atomic_t count; |
33 | struct uts_namespace *uts_ns; |
34 | struct ipc_namespace *ipc_ns; |
35 | struct mnt_namespace *mnt_ns; |
36 | struct pid_namespace *pid_ns_for_children; |
37 | struct net *net_ns; |
38 | struct cgroup_namespace *cgroup_ns; |
39 | }; |
40 | extern struct nsproxy init_nsproxy; |
41 | |
42 | /* |
43 | * the namespaces access rules are: |
44 | * |
45 | * 1. only current task is allowed to change tsk->nsproxy pointer or |
46 | * any pointer on the nsproxy itself. Current must hold the task_lock |
47 | * when changing tsk->nsproxy. |
48 | * |
49 | * 2. when accessing (i.e. reading) current task's namespaces - no |
50 | * precautions should be taken - just dereference the pointers |
51 | * |
52 | * 3. the access to other task namespaces is performed like this |
53 | * task_lock(task); |
54 | * nsproxy = task->nsproxy; |
55 | * if (nsproxy != NULL) { |
56 | * / * |
57 | * * work with the namespaces here |
58 | * * e.g. get the reference on one of them |
59 | * * / |
60 | * } / * |
61 | * * NULL task->nsproxy means that this task is |
62 | * * almost dead (zombie) |
63 | * * / |
64 | * task_unlock(task); |
65 | * |
66 | */ |
67 | |
68 | int copy_namespaces(unsigned long flags, struct task_struct *tsk); |
69 | void exit_task_namespaces(struct task_struct *tsk); |
70 | void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new); |
71 | void free_nsproxy(struct nsproxy *ns); |
72 | int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **, |
73 | struct cred *, struct fs_struct *); |
74 | int __init nsproxy_cache_init(void); |
75 | |
76 | static inline void put_nsproxy(struct nsproxy *ns) |
77 | { |
78 | if (atomic_dec_and_test(&ns->count)) { |
79 | free_nsproxy(ns); |
80 | } |
81 | } |
82 | |
83 | static inline void get_nsproxy(struct nsproxy *ns) |
84 | { |
85 | atomic_inc(&ns->count); |
86 | } |
87 | |
88 | #endif |
89 | |