#ifndef _LINUX_NSPROXY_H #define _LINUX_NSPROXY_H #include <linux/spinlock.h> #include <linux/sched.h> struct mnt_namespace; struct uts_namespace; struct ipc_namespace; struct pid_namespace; /* * A structure to contain pointers to all per-process * namespaces - fs (mount), uts, network, sysvipc, etc. * * 'count' is the number of tasks holding a reference. * The count for each namespace, then, will be the number * of nsproxies pointing to it, not the number of tasks. * * The nsproxy is shared by tasks which share all namespaces. * As soon as a single namespace is cloned or unshared, the * nsproxy is copied. */ struct nsproxy { atomic_t count; struct uts_namespace *uts_ns; struct ipc_namespace *ipc_ns; struct mnt_namespace *mnt_ns; struct pid_namespace *pid_ns; struct user_namespace *user_ns; struct net *net_ns; }; extern struct nsproxy init_nsproxy; /* * the namespaces access rules are: * * 1. only current task is allowed to change tsk->nsproxy pointer or * any pointer on the nsproxy itself * * 2. when accessing (i.e. reading) current task's namespaces - no * precautions should be taken - just dereference the pointers * * 3. the access to other task namespaces is performed like this * rcu_read_lock(); * nsproxy = task_nsproxy(tsk); * if (nsproxy != NULL) { * / * * * work with the namespaces here * * e.g. get the reference on one of them * * / * } / * * * NULL task_nsproxy() means that this task is * * almost dead (zombie) * * / * rcu_read_unlock(); * */ static inline struct nsproxy *task_nsproxy(struct task_struct *tsk) { return rcu_dereference(tsk->nsproxy); } int copy_namespaces(unsigned long flags, struct task_struct *tsk); void exit_task_namespaces(struct task_struct *tsk); void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new); void free_nsproxy(struct nsproxy *ns); int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **, struct fs_struct *); static inline void put_nsproxy(struct nsproxy *ns) { if (atomic_dec_and_test(&ns->count)) { free_nsproxy(ns); } } static inline void get_nsproxy(struct nsproxy *ns) { atomic_inc(&ns->count); } #ifdef CONFIG_CGROUP_NS int ns_cgroup_clone(struct task_struct *tsk); #else static inline int ns_cgroup_clone(struct task_struct *tsk) { return 0; } #endif #endif