nsproxy.h

  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(u64 flags, struct task_struct *tsk);
 96void switch_cred_namespaces(const struct cred *old, const struct cred *new);
 97void exit_nsproxy_namespaces(struct task_struct *tsk);
 98void get_cred_namespaces(struct task_struct *tsk);
 99void exit_cred_namespaces(struct task_struct *tsk);
100void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new);
101int exec_task_namespaces(void);
102void deactivate_nsproxy(struct nsproxy *ns);
103int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **,
104	struct cred *, struct fs_struct *);
105int __init nsproxy_cache_init(void);
106
107static inline void put_nsproxy(struct nsproxy *ns)
108{
109	if (refcount_dec_and_test(&ns->count))
110		deactivate_nsproxy(ns);
111}
112
113static inline void get_nsproxy(struct nsproxy *ns)
114{
115	refcount_inc(&ns->count);
116}
117
118DEFINE_FREE(put_nsproxy, struct nsproxy *, if (_T) put_nsproxy(_T))
119
120#endif