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