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(unsigned long 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(&ns->count))
107		free_nsproxy(ns);
108}
109
110static inline void get_nsproxy(struct nsproxy *ns)
111{
112	refcount_inc(&ns->count);
113}
114
115#endif
116