kernel/nsproxy.c

   1 /*
   2  *  Copyright (C) 2006 IBM Corporation
   3  *
   4  *  Author: Serge Hallyn <serue@us.ibm.com>
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License as
   8  *  published by the Free Software Foundation, version 2 of the
   9  *  License.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/version.h>
  14 #include <linux/nsproxy.h>
  15 #include <linux/init_task.h>
  16
  17 struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
  18
  19 static inline void get_nsproxy(struct nsproxy *ns)
  20 {
  21         atomic_inc(&ns->count);
  22 }
  23
  24 void get_task_namespaces(struct task_struct *tsk)
  25 {
  26         struct nsproxy *ns = tsk->nsproxy;
  27         if (ns) {
  28                 get_nsproxy(ns);
  29         }
  30 }
  31
  32 /*
  33  * creates a copy of "orig" with refcount 1.
  34  * This does not grab references to the contained namespaces,
  35  * so that needs to be done by dup_namespaces.
  36  */
  37 static inline struct nsproxy *clone_namespaces(struct nsproxy *orig)
  38 {
  39         struct nsproxy *ns;
  40
  41         ns = kmalloc(sizeof(struct nsproxy), GFP_KERNEL);
  42         if (ns) {
  43                 memcpy(ns, orig, sizeof(struct nsproxy));
  44                 atomic_set(&ns->count, 1);
  45         }
  46         return ns;
  47 }
  48
  49 /*
  50  * copies the nsproxy, setting refcount to 1, and grabbing a
  51  * reference to all contained namespaces.  Called from
  52  * sys_unshare()
  53  */
  54 struct nsproxy *dup_namespaces(struct nsproxy *orig)
  55 {
  56         struct nsproxy *ns = clone_namespaces(orig);
  57
  58         return ns;
  59 }
  60
  61 /*
  62  * called from clone.  This now handles copy for nsproxy and all
  63  * namespaces therein.
  64  */
  65 int copy_namespaces(int flags, struct task_struct *tsk)
  66 {
  67         struct nsproxy *old_ns = tsk->nsproxy;
  68
  69         if (!old_ns)
  70                 return 0;
  71
  72         get_nsproxy(old_ns);
  73
  74         return 0;
  75 }
  76
  77 void free_nsproxy(struct nsproxy *ns)
  78 {
  79                 kfree(ns);
  80 }