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
9 struct mnt_namespace;
10 struct uts_namespace;
11 struct ipc_namespace;
12 struct pid_namespace;
13 struct cgroup_namespace;
14 struct 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 */
32 struct 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 };
43 extern struct nsproxy init_nsproxy;
44
45 #define to_ns_common(__ns) \
46 _Generic((__ns), \
47 struct cgroup_namespace *: &(__ns->ns), \
48 struct ipc_namespace *: &(__ns->ns), \
49 struct net *: &(__ns->ns), \
50 struct pid_namespace *: &(__ns->ns), \
51 struct mnt_namespace *: &(__ns->ns), \
52 struct time_namespace *: &(__ns->ns), \
53 struct user_namespace *: &(__ns->ns), \
54 struct uts_namespace *: &(__ns->ns))
55
56 /*
57 * A structure to encompass all bits needed to install
58 * a partial or complete new set of namespaces.
59 *
60 * If a new user namespace is requested cred will
61 * point to a modifiable set of credentials. If a pointer
62 * to a modifiable set is needed nsset_cred() must be
63 * used and tested.
64 */
65 struct nsset {
66 unsigned flags;
67 struct nsproxy *nsproxy;
68 struct fs_struct *fs;
69 const struct cred *cred;
70 };
71
nsset_cred(struct nsset * set)72 static inline struct cred *nsset_cred(struct nsset *set)
73 {
74 if (set->flags & CLONE_NEWUSER)
75 return (struct cred *)set->cred;
76
77 return NULL;
78 }
79
80 /*
81 * the namespaces access rules are:
82 *
83 * 1. only current task is allowed to change tsk->nsproxy pointer or
84 * any pointer on the nsproxy itself. Current must hold the task_lock
85 * when changing tsk->nsproxy.
86 *
87 * 2. when accessing (i.e. reading) current task's namespaces - no
88 * precautions should be taken - just dereference the pointers
89 *
90 * 3. the access to other task namespaces is performed like this
91 * task_lock(task);
92 * nsproxy = task->nsproxy;
93 * if (nsproxy != NULL) {
94 * / *
95 * * work with the namespaces here
96 * * e.g. get the reference on one of them
97 * * /
98 * } / *
99 * * NULL task->nsproxy means that this task is
100 * * almost dead (zombie)
101 * * /
102 * task_unlock(task);
103 *
104 */
105
106 int copy_namespaces(unsigned long flags, struct task_struct *tsk);
107 void exit_task_namespaces(struct task_struct *tsk);
108 void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new);
109 int exec_task_namespaces(void);
110 void free_nsproxy(struct nsproxy *ns);
111 int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **,
112 struct cred *, struct fs_struct *);
113 int __init nsproxy_cache_init(void);
114
put_nsproxy(struct nsproxy * ns)115 static inline void put_nsproxy(struct nsproxy *ns)
116 {
117 if (refcount_dec_and_test(&ns->count))
118 free_nsproxy(ns);
119 }
120
get_nsproxy(struct nsproxy * ns)121 static inline void get_nsproxy(struct nsproxy *ns)
122 {
123 refcount_inc(&ns->count);
124 }
125
126 DEFINE_FREE(put_nsproxy, struct nsproxy *, if (_T) put_nsproxy(_T))
127
128 #endif
129