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/mnt_namespace.h>
  21 #include <linux/utsname.h>
  22 #include <linux/pid_namespace.h>
  23
  24 struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
  25
  26 static inline void get_nsproxy(struct nsproxy *ns)
  27 {
  28         atomic_inc(&ns->count);
  29 }
  30
  31 void get_task_namespaces(struct task_struct *tsk)
  32 {
  33         struct nsproxy *ns = tsk->nsproxy;
  34         if (ns) {
  35                 get_nsproxy(ns);
  36         }
  37 }
  38
  39 /*
  40  * creates a copy of "orig" with refcount 1.
  41  * This does not grab references to the contained namespaces,
  42  * so that needs to be done by dup_namespaces.
  43  */
  44 static inline struct nsproxy *clone_namespaces(struct nsproxy *orig)
  45 {
  46         struct nsproxy *ns;
  47
  48         ns = kmemdup(orig, sizeof(struct nsproxy), GFP_KERNEL);
  49         if (ns) {
  50                 atomic_set(&ns->count, 1);
  51                 ns->id = -1;
  52         }
  53         return ns;
  54 }
  55
  56 /*
  57  * copies the nsproxy, setting refcount to 1, and grabbing a
  58  * reference to all contained namespaces.  Called from
  59  * sys_unshare()
  60  */
  61 struct nsproxy *dup_namespaces(struct nsproxy *orig)
  62 {
  63         struct nsproxy *ns = clone_namespaces(orig);
  64
  65         if (ns) {
  66                 if (ns->mnt_ns)
  67                         get_mnt_ns(ns->mnt_ns);
  68                 if (ns->uts_ns)
  69                         get_uts_ns(ns->uts_ns);
  70                 if (ns->ipc_ns)
  71                         get_ipc_ns(ns->ipc_ns);
  72                 if (ns->pid_ns)
  73                         get_pid_ns(ns->pid_ns);
  74         }
  75
  76         return ns;
  77 }
  78
  79 /*
  80  * called from clone.  This now handles copy for nsproxy and all
  81  * namespaces therein.
  82  */
  83 int copy_namespaces(int flags, struct task_struct *tsk)
  84 {
  85         struct nsproxy *old_ns = tsk->nsproxy;
  86         struct nsproxy *new_ns;
  87         int err = 0;
  88
  89         if (!old_ns)
  90                 return 0;
  91
  92         get_nsproxy(old_ns);
  93
  94         if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC)))
  95                 return 0;
  96
  97         new_ns = clone_namespaces(old_ns);
  98         if (!new_ns) {
  99                 err = -ENOMEM;
 100                 goto out;
 101         }
 102
 103         tsk->nsproxy = new_ns;
 104
 105         err = copy_mnt_ns(flags, tsk);
 106         if (err)
 107                 goto out_ns;
 108
 109         err = copy_utsname(flags, tsk);
 110         if (err)
 111                 goto out_uts;
 112
 113         err = copy_ipcs(flags, tsk);
 114         if (err)
 115                 goto out_ipc;
 116
 117         err = copy_pid_ns(flags, tsk);
 118         if (err)
 119                 goto out_pid;
 120
 121 out:
 122         put_nsproxy(old_ns);
 123         return err;
 124
 125 out_pid:
 126         if (new_ns->ipc_ns)
 127                 put_ipc_ns(new_ns->ipc_ns);
 128 out_ipc:
 129         if (new_ns->uts_ns)
 130                 put_uts_ns(new_ns->uts_ns);
 131 out_uts:
 132         if (new_ns->mnt_ns)
 133                 put_mnt_ns(new_ns->mnt_ns);
 134 out_ns:
 135         tsk->nsproxy = old_ns;
 136         kfree(new_ns);
 137         goto out;
 138 }
 139
 140 void free_nsproxy(struct nsproxy *ns)
 141 {
 142         if (ns->mnt_ns)
 143                 put_mnt_ns(ns->mnt_ns);
 144         if (ns->uts_ns)
 145                 put_uts_ns(ns->uts_ns);
 146         if (ns->ipc_ns)
 147                 put_ipc_ns(ns->ipc_ns);
 148         if (ns->pid_ns)
 149                 put_pid_ns(ns->pid_ns);
 150         kfree(ns);
 151 }