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 8 struct mnt_namespace; 9 struct uts_namespace; 10 struct ipc_namespace; 11 struct pid_namespace; 12 struct cgroup_namespace; 13 struct 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 */ 31 struct 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 time_namespace *time_ns; 39 struct time_namespace *time_ns_for_children; 40 struct cgroup_namespace *cgroup_ns; 41 }; 42 extern struct nsproxy init_nsproxy; 43 44 /* 45 * the namespaces access rules are: 46 * 47 * 1. only current task is allowed to change tsk->nsproxy pointer or 48 * any pointer on the nsproxy itself. Current must hold the task_lock 49 * when changing tsk->nsproxy. 50 * 51 * 2. when accessing (i.e. reading) current task's namespaces - no 52 * precautions should be taken - just dereference the pointers 53 * 54 * 3. the access to other task namespaces is performed like this 55 * task_lock(task); 56 * nsproxy = task->nsproxy; 57 * if (nsproxy != NULL) { 58 * / * 59 * * work with the namespaces here 60 * * e.g. get the reference on one of them 61 * * / 62 * } / * 63 * * NULL task->nsproxy means that this task is 64 * * almost dead (zombie) 65 * * / 66 * task_unlock(task); 67 * 68 */ 69 70 int copy_namespaces(unsigned long flags, struct task_struct *tsk); 71 void exit_task_namespaces(struct task_struct *tsk); 72 void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new); 73 void free_nsproxy(struct nsproxy *ns); 74 int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **, 75 struct cred *, struct fs_struct *); 76 int __init nsproxy_cache_init(void); 77 78 static inline void put_nsproxy(struct nsproxy *ns) 79 { 80 if (atomic_dec_and_test(&ns->count)) { 81 free_nsproxy(ns); 82 } 83 } 84 85 static inline void get_nsproxy(struct nsproxy *ns) 86 { 87 atomic_inc(&ns->count); 88 } 89 90 #endif 91