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 | /* |
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 | */ |
54 | struct nsset { |
55 | unsigned flags; |
56 | struct nsproxy *nsproxy; |
57 | struct fs_struct *fs; |
58 | const struct cred *cred; |
59 | }; |
60 | |
61 | static 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 | |
95 | int copy_namespaces(unsigned long flags, struct task_struct *tsk); |
96 | void exit_task_namespaces(struct task_struct *tsk); |
97 | void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new); |
98 | int exec_task_namespaces(void); |
99 | void free_nsproxy(struct nsproxy *ns); |
100 | int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **, |
101 | struct cred *, struct fs_struct *); |
102 | int __init nsproxy_cache_init(void); |
103 | |
104 | static inline void put_nsproxy(struct nsproxy *ns) |
105 | { |
106 | if (refcount_dec_and_test(r: &ns->count)) |
107 | free_nsproxy(ns); |
108 | } |
109 | |
110 | static inline void get_nsproxy(struct nsproxy *ns) |
111 | { |
112 | refcount_inc(r: &ns->count); |
113 | } |
114 | |
115 | #endif |
116 | |