116 lines
3.1 KiB
C
116 lines
3.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_NSPROXY_H
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#define _LINUX_NSPROXY_H
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#include <linux/spinlock.h>
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#include <linux/sched.h>
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struct mnt_namespace;
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struct uts_namespace;
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struct ipc_namespace;
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struct pid_namespace;
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struct cgroup_namespace;
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struct fs_struct;
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/*
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* A structure to contain pointers to all per-process
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* namespaces - fs (mount), uts, network, sysvipc, etc.
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*
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* The pid namespace is an exception -- it's accessed using
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* task_active_pid_ns. The pid namespace here is the
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* namespace that children will use.
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*
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* 'count' is the number of tasks holding a reference.
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* The count for each namespace, then, will be the number
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* of nsproxies pointing to it, not the number of tasks.
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*
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* The nsproxy is shared by tasks which share all namespaces.
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* As soon as a single namespace is cloned or unshared, the
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* nsproxy is copied.
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*/
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struct nsproxy {
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atomic_t count;
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struct uts_namespace *uts_ns;
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struct ipc_namespace *ipc_ns;
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struct mnt_namespace *mnt_ns;
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struct pid_namespace *pid_ns_for_children;
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struct net *net_ns;
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struct time_namespace *time_ns;
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struct time_namespace *time_ns_for_children;
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struct cgroup_namespace *cgroup_ns;
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};
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extern struct nsproxy init_nsproxy;
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/*
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* A structure to encompass all bits needed to install
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* a partial or complete new set of namespaces.
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*
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* If a new user namespace is requested cred will
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* point to a modifiable set of credentials. If a pointer
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* to a modifiable set is needed nsset_cred() must be
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* used and tested.
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*/
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struct nsset {
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unsigned flags;
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struct nsproxy *nsproxy;
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struct fs_struct *fs;
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const struct cred *cred;
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};
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static inline struct cred *nsset_cred(struct nsset *set)
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{
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if (set->flags & CLONE_NEWUSER)
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return (struct cred *)set->cred;
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return NULL;
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}
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/*
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* the namespaces access rules are:
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*
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* 1. only current task is allowed to change tsk->nsproxy pointer or
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* any pointer on the nsproxy itself. Current must hold the task_lock
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* when changing tsk->nsproxy.
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*
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* 2. when accessing (i.e. reading) current task's namespaces - no
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* precautions should be taken - just dereference the pointers
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*
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* 3. the access to other task namespaces is performed like this
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* task_lock(task);
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* nsproxy = task->nsproxy;
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* if (nsproxy != NULL) {
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* / *
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* * work with the namespaces here
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* * e.g. get the reference on one of them
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* * /
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* } / *
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* * NULL task->nsproxy means that this task is
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* * almost dead (zombie)
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* * /
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* task_unlock(task);
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*
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*/
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int copy_namespaces(unsigned long flags, struct task_struct *tsk);
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void exit_task_namespaces(struct task_struct *tsk);
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void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new);
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int exec_task_namespaces(void);
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void free_nsproxy(struct nsproxy *ns);
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int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **,
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struct cred *, struct fs_struct *);
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int __init nsproxy_cache_init(void);
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static inline void put_nsproxy(struct nsproxy *ns)
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{
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if (atomic_dec_and_test(&ns->count)) {
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free_nsproxy(ns);
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}
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}
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static inline void get_nsproxy(struct nsproxy *ns)
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{
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atomic_inc(&ns->count);
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}
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#endif
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