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