1/* SPDX-License-Identifier: GPL-2.0 */ 2#ifndef _LINUX_NSPROXY_H 3#define _LINUX_NSPROXY_H 4 5#include <linux/refcount.h> 6#include <linux/spinlock.h> 7#include <linux/sched.h> 8 9struct mnt_namespace; 10struct uts_namespace; 11struct ipc_namespace; 12struct pid_namespace; 13struct cgroup_namespace; 14struct fs_struct; 15 16/* 17 * A structure to contain pointers to all per-process 18 * namespaces - fs (mount), uts, network, sysvipc, etc. 19 * 20 * The pid namespace is an exception -- it's accessed using 21 * task_active_pid_ns. The pid namespace here is the 22 * namespace that children will use. 23 * 24 * 'count' is the number of tasks holding a reference. 25 * The count for each namespace, then, will be the number 26 * of nsproxies pointing to it, not the number of tasks. 27 * 28 * The nsproxy is shared by tasks which share all namespaces. 29 * As soon as a single namespace is cloned or unshared, the 30 * nsproxy is copied. 31 */ 32struct nsproxy { 33 refcount_t count; 34 struct uts_namespace *uts_ns; 35 struct ipc_namespace *ipc_ns; 36 struct mnt_namespace *mnt_ns; 37 struct pid_namespace *pid_ns_for_children; 38 struct net *net_ns; 39 struct time_namespace *time_ns; 40 struct time_namespace *time_ns_for_children; 41 struct cgroup_namespace *cgroup_ns; 42}; 43extern struct nsproxy init_nsproxy; 44 45/* 46 * A structure to encompass all bits needed to install 47 * a partial or complete new set of namespaces. 48 * 49 * If a new user namespace is requested cred will 50 * point to a modifiable set of credentials. If a pointer 51 * to a modifiable set is needed nsset_cred() must be 52 * used and tested. 53 */ 54struct nsset { 55 unsigned flags; 56 struct nsproxy *nsproxy; 57 struct fs_struct *fs; 58 const struct cred *cred; 59}; 60 61static inline struct cred *nsset_cred(struct nsset *set) 62{ 63 if (set->flags & CLONE_NEWUSER) 64 return (struct cred *)set->cred; 65 66 return NULL; 67} 68 69/* 70 * the namespaces access rules are: 71 * 72 * 1. only current task is allowed to change tsk->nsproxy pointer or 73 * any pointer on the nsproxy itself. Current must hold the task_lock 74 * when changing tsk->nsproxy. 75 * 76 * 2. when accessing (i.e. reading) current task's namespaces - no 77 * precautions should be taken - just dereference the pointers 78 * 79 * 3. the access to other task namespaces is performed like this 80 * task_lock(task); 81 * nsproxy = task->nsproxy; 82 * if (nsproxy != NULL) { 83 * / * 84 * * work with the namespaces here 85 * * e.g. get the reference on one of them 86 * * / 87 * } / * 88 * * NULL task->nsproxy means that this task is 89 * * almost dead (zombie) 90 * * / 91 * task_unlock(task); 92 * 93 */ 94 95int copy_namespaces(unsigned long flags, struct task_struct *tsk); 96void exit_task_namespaces(struct task_struct *tsk); 97void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new); 98int exec_task_namespaces(void); 99void free_nsproxy(struct nsproxy *ns); 100int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **, 101 struct cred *, struct fs_struct *); 102int __init nsproxy_cache_init(void); 103 104static inline void put_nsproxy(struct nsproxy *ns) 105{ 106 if (refcount_dec_and_test(&ns->count)) 107 free_nsproxy(ns); 108} 109 110static inline void get_nsproxy(struct nsproxy *ns) 111{ 112 refcount_inc(&ns->count); 113} 114 115#endif 116