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