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 #include <linux/namespace.h>
  17 #include <linux/utsname.h>
  18
  19 struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
  20
  21 static inline void get_nsproxy(struct nsproxy *ns)
  22 {
  23         atomic_inc(&ns->count);
  24 }
  25
  26 void get_task_namespaces(struct task_struct *tsk)
  27 {
  28         struct nsproxy *ns = tsk->nsproxy;
  29         if (ns) {
  30                 get_nsproxy(ns);
  31         }
  32 }
  33
  34 /*
  35  * creates a copy of "orig" with refcount 1.
  36  * This does not grab references to the contained namespaces,
  37  * so that needs to be done by dup_namespaces.
  38  */
  39 static inline struct nsproxy *clone_namespaces(struct nsproxy *orig)
  40 {
  41         struct nsproxy *ns;
  42
  43         ns = kmalloc(sizeof(struct nsproxy), GFP_KERNEL);
  44         if (ns) {
  45                 memcpy(ns, orig, sizeof(struct nsproxy));
  46                 atomic_set(&ns->count, 1);
  47         }
  48         return ns;
  49 }
  50
  51 /*
  52  * copies the nsproxy, setting refcount to 1, and grabbing a
  53  * reference to all contained namespaces.  Called from
  54  * sys_unshare()
  55  */
  56 struct nsproxy *dup_namespaces(struct nsproxy *orig)
  57 {
  58         struct nsproxy *ns = clone_namespaces(orig);
  59
  60         if (ns) {
  61                 if (ns->namespace)
  62                         get_namespace(ns->namespace);
  63                 if (ns->uts_ns)
  64                         get_uts_ns(ns->uts_ns);
  65         }
  66
  67         return ns;
  68 }
  69
  70 /*
  71  * called from clone.  This now handles copy for nsproxy and all
  72  * namespaces therein.
  73  */
  74 int copy_namespaces(int flags, struct task_struct *tsk)
  75 {
  76         struct nsproxy *old_ns = tsk->nsproxy;
  77         struct nsproxy *new_ns;
  78         int err = 0;
  79
  80         if (!old_ns)
  81                 return 0;
  82
  83         get_nsproxy(old_ns);
  84
  85         if (!(flags & CLONE_NEWNS))
  86                 return 0;
  87
  88         new_ns = clone_namespaces(old_ns);
  89         if (!new_ns) {
  90                 err = -ENOMEM;
  91                 goto out;
  92         }
  93
  94         tsk->nsproxy = new_ns;
  95
  96         err = copy_namespace(flags, tsk);
  97         if (err) {
  98                 tsk->nsproxy = old_ns;
  99                 put_nsproxy(new_ns);
 100                 goto out;
 101         }
 102
 103         err = copy_utsname(flags, tsk);
 104         if (err) {
 105                 if (new_ns->namespace)
 106                         put_namespace(new_ns->namespace);
 107                 tsk->nsproxy = old_ns;
 108                 put_nsproxy(new_ns);
 109                 goto out;
 110         }
 111
 112 out:
 113         put_nsproxy(old_ns);
 114         return err;
 115 }
 116
 117 void free_nsproxy(struct nsproxy *ns)
 118 {
 119                 if (ns->namespace)
 120                         put_namespace(ns->namespace);
 121                 if (ns->uts_ns)
 122                         put_uts_ns(ns->uts_ns);
 123                 kfree(ns);
 124 }