1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_NSPROXY_H
3#define _LINUX_NSPROXY_H
4
5#include <linux/refcount.h>
6#include <linux/spinlock.h>
7#include <linux/sched.h>
8
9struct mnt_namespace;
10struct uts_namespace;
11struct ipc_namespace;
12struct pid_namespace;
13struct cgroup_namespace;
14struct fs_struct;
15
16/*
17 * A structure to contain pointers to all per-process
18 * namespaces - fs (mount), uts, network, sysvipc, etc.
19 *
20 * The pid namespace is an exception -- it's accessed using
21 * task_active_pid_ns. The pid namespace here is the
22 * namespace that children will use.
23 *
24 * 'count' is the number of tasks holding a reference.
25 * The count for each namespace, then, will be the number
26 * of nsproxies pointing to it, not the number of tasks.
27 *
28 * The nsproxy is shared by tasks which share all namespaces.
29 * As soon as a single namespace is cloned or unshared, the
30 * nsproxy is copied.
31 */
32struct nsproxy {
33 refcount_t count;
34 struct uts_namespace *uts_ns;
35 struct ipc_namespace *ipc_ns;
36 struct mnt_namespace *mnt_ns;
37 struct pid_namespace *pid_ns_for_children;
38 struct net *net_ns;
39 struct time_namespace *time_ns;
40 struct time_namespace *time_ns_for_children;
41 struct cgroup_namespace *cgroup_ns;
42};
43extern struct nsproxy init_nsproxy;
44
45/*
46 * A structure to encompass all bits needed to install
47 * a partial or complete new set of namespaces.
48 *
49 * If a new user namespace is requested cred will
50 * point to a modifiable set of credentials. If a pointer
51 * to a modifiable set is needed nsset_cred() must be
52 * used and tested.
53 */
54struct nsset {
55 unsigned flags;
56 struct nsproxy *nsproxy;
57 struct fs_struct *fs;
58 const struct cred *cred;
59};
60
61static inline struct cred *nsset_cred(struct nsset *set)
62{
63 if (set->flags & CLONE_NEWUSER)
64 return (struct cred *)set->cred;
65
66 return NULL;
67}
68
69/*
70 * the namespaces access rules are:
71 *
72 * 1. only current task is allowed to change tsk->nsproxy pointer or
73 * any pointer on the nsproxy itself. Current must hold the task_lock
74 * when changing tsk->nsproxy.
75 *
76 * 2. when accessing (i.e. reading) current task's namespaces - no
77 * precautions should be taken - just dereference the pointers
78 *
79 * 3. the access to other task namespaces is performed like this
80 * task_lock(task);
81 * nsproxy = task->nsproxy;
82 * if (nsproxy != NULL) {
83 * / *
84 * * work with the namespaces here
85 * * e.g. get the reference on one of them
86 * * /
87 * } / *
88 * * NULL task->nsproxy means that this task is
89 * * almost dead (zombie)
90 * * /
91 * task_unlock(task);
92 *
93 */
94
95int copy_namespaces(u64 flags, struct task_struct *tsk);
96void exit_task_namespaces(struct task_struct *tsk);
97void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new);
98int exec_task_namespaces(void);
99void free_nsproxy(struct nsproxy *ns);
100int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **,
101 struct cred *, struct fs_struct *);
102int __init nsproxy_cache_init(void);
103
104static inline void put_nsproxy(struct nsproxy *ns)
105{
106 if (refcount_dec_and_test(r: &ns->count))
107 free_nsproxy(ns);
108}
109
110static inline void get_nsproxy(struct nsproxy *ns)
111{
112 refcount_inc(r: &ns->count);
113}
114
115DEFINE_FREE(put_nsproxy, struct nsproxy *, if (_T) put_nsproxy(_T))
116
117#endif
118