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