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  *  Jun 2006 - namespaces support
  12  *             OpenVZ, SWsoft Inc.
  13  *             Pavel Emelianov <xemul@openvz.org>
  14  */
  15
  16 #include <linux/module.h>
  17 #include <linux/version.h>
  18 #include <linux/nsproxy.h>
  19 #include <linux/init_task.h>
  20 #include <linux/namespace.h>
  21 #include <linux/utsname.h>
  22
  23 struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
  24
  25 static inline void get_nsproxy(struct nsproxy *ns)
  26 {
  27         atomic_inc(&ns->count);
  28 }
  29
  30 void get_task_namespaces(struct task_struct *tsk)
  31 {
  32         struct nsproxy *ns = tsk->nsproxy;
  33         if (ns) {
  34                 get_nsproxy(ns);
  35         }
  36 }
  37
  38 /*
  39  * creates a copy of "orig" with refcount 1.
  40  * This does not grab references to the contained namespaces,
  41  * so that needs to be done by dup_namespaces.
  42  */
  43 static inline struct nsproxy *clone_namespaces(struct nsproxy *orig)
  44 {
  45         struct nsproxy *ns;
  46
  47         ns = kmemdup(orig, sizeof(struct nsproxy), GFP_KERNEL);
  48         if (ns)
  49                 atomic_set(&ns->count, 1);
  50         return ns;
  51 }
  52
  53 /*
  54  * copies the nsproxy, setting refcount to 1, and grabbing a
  55  * reference to all contained namespaces.  Called from
  56  * sys_unshare()
  57  */
  58 struct nsproxy *dup_namespaces(struct nsproxy *orig)
  59 {
  60         struct nsproxy *ns = clone_namespaces(orig);
  61
  62         if (ns) {
  63                 if (ns->namespace)
  64                         get_namespace(ns->namespace);
  65                 if (ns->uts_ns)
  66                         get_uts_ns(ns->uts_ns);
  67                 if (ns->ipc_ns)
  68                         get_ipc_ns(ns->ipc_ns);
  69         }
  70
  71         return ns;
  72 }
  73
  74 /*
  75  * called from clone.  This now handles copy for nsproxy and all
  76  * namespaces therein.
  77  */
  78 int copy_namespaces(int flags, struct task_struct *tsk)
  79 {
  80         struct nsproxy *old_ns = tsk->nsproxy;
  81         struct nsproxy *new_ns;
  82         int err = 0;
  83
  84         if (!old_ns)
  85                 return 0;
  86
  87         get_nsproxy(old_ns);
  88
  89         if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC)))
  90                 return 0;
  91
  92         new_ns = clone_namespaces(old_ns);
  93         if (!new_ns) {
  94                 err = -ENOMEM;
  95                 goto out;
  96         }
  97
  98         tsk->nsproxy = new_ns;
  99
 100         err = copy_namespace(flags, tsk);
 101         if (err)
 102                 goto out_ns;
 103
 104         err = copy_utsname(flags, tsk);
 105         if (err)
 106                 goto out_uts;
 107
 108         err = copy_ipcs(flags, tsk);
 109         if (err)
 110                 goto out_ipc;
 111
 112 out:
 113         put_nsproxy(old_ns);
 114         return err;
 115
 116 out_ipc:
 117         if (new_ns->uts_ns)
 118                 put_uts_ns(new_ns->uts_ns);
 119 out_uts:
 120         if (new_ns->namespace)
 121                 put_namespace(new_ns->namespace);
 122 out_ns:
 123         tsk->nsproxy = old_ns;
 124         kfree(new_ns);
 125         goto out;
 126 }
 127
 128 void free_nsproxy(struct nsproxy *ns)
 129 {
 130                 if (ns->namespace)
 131                         put_namespace(ns->namespace);
 132                 if (ns->uts_ns)
 133                         put_uts_ns(ns->uts_ns);
 134                 if (ns->ipc_ns)
 135                         put_ipc_ns(ns->ipc_ns);
 136                 kfree(ns);
 137 }