1 #ifndef _LINUX_NSPROXY_H 2 #define _LINUX_NSPROXY_H 3 4 #include <linux/spinlock.h> 5 #include <linux/sched.h> 6 7 struct mnt_namespace; 8 struct uts_namespace; 9 struct ipc_namespace; 10 struct pid_namespace; 11 12 /* 13 * A structure to contain pointers to all per-process 14 * namespaces - fs (mount), uts, network, sysvipc, etc. 15 * 16 * 'count' is the number of tasks holding a reference. 17 * The count for each namespace, then, will be the number 18 * of nsproxies pointing to it, not the number of tasks. 19 * 20 * The nsproxy is shared by tasks which share all namespaces. 21 * As soon as a single namespace is cloned or unshared, the 22 * nsproxy is copied. 23 */ 24 struct nsproxy { 25 atomic_t count; 26 struct uts_namespace *uts_ns; 27 struct ipc_namespace *ipc_ns; 28 struct mnt_namespace *mnt_ns; 29 struct pid_namespace *pid_ns; 30 struct user_namespace *user_ns; 31 struct net *net_ns; 32 }; 33 extern 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 40 * 41 * 2. when accessing (i.e. reading) current task's namespaces - no 42 * precautions should be taken - just dereference the pointers 43 * 44 * 3. the access to other task namespaces is performed like this 45 * rcu_read_lock(); 46 * nsproxy = task_nsproxy(tsk); 47 * if (nsproxy != NULL) { 48 * / * 49 * * work with the namespaces here 50 * * e.g. get the reference on one of them 51 * * / 52 * } / * 53 * * NULL task_nsproxy() means that this task is 54 * * almost dead (zombie) 55 * * / 56 * rcu_read_unlock(); 57 * 58 */ 59 60 static inline struct nsproxy *task_nsproxy(struct task_struct *tsk) 61 { 62 return rcu_dereference(tsk->nsproxy); 63 } 64 65 int copy_namespaces(unsigned long flags, struct task_struct *tsk); 66 void exit_task_namespaces(struct task_struct *tsk); 67 void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new); 68 void free_nsproxy(struct nsproxy *ns); 69 int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **, 70 struct fs_struct *); 71 72 static inline void put_nsproxy(struct nsproxy *ns) 73 { 74 if (atomic_dec_and_test(&ns->count)) { 75 free_nsproxy(ns); 76 } 77 } 78 79 static inline void get_nsproxy(struct nsproxy *ns) 80 { 81 atomic_inc(&ns->count); 82 } 83 84 #ifdef CONFIG_CGROUP_NS 85 int ns_cgroup_clone(struct task_struct *tsk); 86 #else 87 static inline int ns_cgroup_clone(struct task_struct *tsk) { return 0; } 88 #endif 89 90 #endif 91