1*4882a593Smuzhiyun /* SPDX-License-Identifier: GPL-2.0 */
2*4882a593Smuzhiyun #ifndef _LINUX_NSPROXY_H
3*4882a593Smuzhiyun #define _LINUX_NSPROXY_H
4*4882a593Smuzhiyun
5*4882a593Smuzhiyun #include <linux/spinlock.h>
6*4882a593Smuzhiyun #include <linux/sched.h>
7*4882a593Smuzhiyun
8*4882a593Smuzhiyun struct mnt_namespace;
9*4882a593Smuzhiyun struct uts_namespace;
10*4882a593Smuzhiyun struct ipc_namespace;
11*4882a593Smuzhiyun struct pid_namespace;
12*4882a593Smuzhiyun struct cgroup_namespace;
13*4882a593Smuzhiyun struct fs_struct;
14*4882a593Smuzhiyun
15*4882a593Smuzhiyun /*
16*4882a593Smuzhiyun * A structure to contain pointers to all per-process
17*4882a593Smuzhiyun * namespaces - fs (mount), uts, network, sysvipc, etc.
18*4882a593Smuzhiyun *
19*4882a593Smuzhiyun * The pid namespace is an exception -- it's accessed using
20*4882a593Smuzhiyun * task_active_pid_ns. The pid namespace here is the
21*4882a593Smuzhiyun * namespace that children will use.
22*4882a593Smuzhiyun *
23*4882a593Smuzhiyun * 'count' is the number of tasks holding a reference.
24*4882a593Smuzhiyun * The count for each namespace, then, will be the number
25*4882a593Smuzhiyun * of nsproxies pointing to it, not the number of tasks.
26*4882a593Smuzhiyun *
27*4882a593Smuzhiyun * The nsproxy is shared by tasks which share all namespaces.
28*4882a593Smuzhiyun * As soon as a single namespace is cloned or unshared, the
29*4882a593Smuzhiyun * nsproxy is copied.
30*4882a593Smuzhiyun */
31*4882a593Smuzhiyun struct nsproxy {
32*4882a593Smuzhiyun atomic_t count;
33*4882a593Smuzhiyun struct uts_namespace *uts_ns;
34*4882a593Smuzhiyun struct ipc_namespace *ipc_ns;
35*4882a593Smuzhiyun struct mnt_namespace *mnt_ns;
36*4882a593Smuzhiyun struct pid_namespace *pid_ns_for_children;
37*4882a593Smuzhiyun struct net *net_ns;
38*4882a593Smuzhiyun struct time_namespace *time_ns;
39*4882a593Smuzhiyun struct time_namespace *time_ns_for_children;
40*4882a593Smuzhiyun struct cgroup_namespace *cgroup_ns;
41*4882a593Smuzhiyun };
42*4882a593Smuzhiyun extern struct nsproxy init_nsproxy;
43*4882a593Smuzhiyun
44*4882a593Smuzhiyun /*
45*4882a593Smuzhiyun * A structure to encompass all bits needed to install
46*4882a593Smuzhiyun * a partial or complete new set of namespaces.
47*4882a593Smuzhiyun *
48*4882a593Smuzhiyun * If a new user namespace is requested cred will
49*4882a593Smuzhiyun * point to a modifiable set of credentials. If a pointer
50*4882a593Smuzhiyun * to a modifiable set is needed nsset_cred() must be
51*4882a593Smuzhiyun * used and tested.
52*4882a593Smuzhiyun */
53*4882a593Smuzhiyun struct nsset {
54*4882a593Smuzhiyun unsigned flags;
55*4882a593Smuzhiyun struct nsproxy *nsproxy;
56*4882a593Smuzhiyun struct fs_struct *fs;
57*4882a593Smuzhiyun const struct cred *cred;
58*4882a593Smuzhiyun };
59*4882a593Smuzhiyun
nsset_cred(struct nsset * set)60*4882a593Smuzhiyun static inline struct cred *nsset_cred(struct nsset *set)
61*4882a593Smuzhiyun {
62*4882a593Smuzhiyun if (set->flags & CLONE_NEWUSER)
63*4882a593Smuzhiyun return (struct cred *)set->cred;
64*4882a593Smuzhiyun
65*4882a593Smuzhiyun return NULL;
66*4882a593Smuzhiyun }
67*4882a593Smuzhiyun
68*4882a593Smuzhiyun /*
69*4882a593Smuzhiyun * the namespaces access rules are:
70*4882a593Smuzhiyun *
71*4882a593Smuzhiyun * 1. only current task is allowed to change tsk->nsproxy pointer or
72*4882a593Smuzhiyun * any pointer on the nsproxy itself. Current must hold the task_lock
73*4882a593Smuzhiyun * when changing tsk->nsproxy.
74*4882a593Smuzhiyun *
75*4882a593Smuzhiyun * 2. when accessing (i.e. reading) current task's namespaces - no
76*4882a593Smuzhiyun * precautions should be taken - just dereference the pointers
77*4882a593Smuzhiyun *
78*4882a593Smuzhiyun * 3. the access to other task namespaces is performed like this
79*4882a593Smuzhiyun * task_lock(task);
80*4882a593Smuzhiyun * nsproxy = task->nsproxy;
81*4882a593Smuzhiyun * if (nsproxy != NULL) {
82*4882a593Smuzhiyun * / *
83*4882a593Smuzhiyun * * work with the namespaces here
84*4882a593Smuzhiyun * * e.g. get the reference on one of them
85*4882a593Smuzhiyun * * /
86*4882a593Smuzhiyun * } / *
87*4882a593Smuzhiyun * * NULL task->nsproxy means that this task is
88*4882a593Smuzhiyun * * almost dead (zombie)
89*4882a593Smuzhiyun * * /
90*4882a593Smuzhiyun * task_unlock(task);
91*4882a593Smuzhiyun *
92*4882a593Smuzhiyun */
93*4882a593Smuzhiyun
94*4882a593Smuzhiyun int copy_namespaces(unsigned long flags, struct task_struct *tsk);
95*4882a593Smuzhiyun void exit_task_namespaces(struct task_struct *tsk);
96*4882a593Smuzhiyun void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new);
97*4882a593Smuzhiyun void free_nsproxy(struct nsproxy *ns);
98*4882a593Smuzhiyun int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **,
99*4882a593Smuzhiyun struct cred *, struct fs_struct *);
100*4882a593Smuzhiyun int __init nsproxy_cache_init(void);
101*4882a593Smuzhiyun
put_nsproxy(struct nsproxy * ns)102*4882a593Smuzhiyun static inline void put_nsproxy(struct nsproxy *ns)
103*4882a593Smuzhiyun {
104*4882a593Smuzhiyun if (atomic_dec_and_test(&ns->count)) {
105*4882a593Smuzhiyun free_nsproxy(ns);
106*4882a593Smuzhiyun }
107*4882a593Smuzhiyun }
108*4882a593Smuzhiyun
get_nsproxy(struct nsproxy * ns)109*4882a593Smuzhiyun static inline void get_nsproxy(struct nsproxy *ns)
110*4882a593Smuzhiyun {
111*4882a593Smuzhiyun atomic_inc(&ns->count);
112*4882a593Smuzhiyun }
113*4882a593Smuzhiyun
114*4882a593Smuzhiyun #endif
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