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  */
  42 static inline struct nsproxy *clone_nsproxy(struct nsproxy *orig)
  43 {
  44         struct nsproxy *ns;
  45
  46         ns = kmemdup(orig, sizeof(struct nsproxy), GFP_KERNEL);
  47         if (ns)
  48                 atomic_set(&ns->count, 1);
  49         return ns;
  50 }
  51
  52 /*
  53  * Create new nsproxy and all of its the associated namespaces.
  54  * Return the newly created nsproxy.  Do not attach this to the task,
  55  * leave it to the caller to do proper locking and attach it to task.
  56  */
  57 static struct nsproxy *create_new_namespaces(int flags, struct task_struct *tsk,
  58                         struct fs_struct *new_fs)
  59 {
  60         struct nsproxy *new_nsp;
  61
  62         new_nsp = clone_nsproxy(tsk->nsproxy);
  63         if (!new_nsp)
  64                 return ERR_PTR(-ENOMEM);
  65
  66         new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, new_fs);
  67         if (IS_ERR(new_nsp->mnt_ns))
  68                 goto out_ns;
  69
  70         new_nsp->uts_ns = copy_utsname(flags, tsk->nsproxy->uts_ns);
  71         if (IS_ERR(new_nsp->uts_ns))
  72                 goto out_uts;
  73
  74         new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns);
  75         if (IS_ERR(new_nsp->ipc_ns))
  76                 goto out_ipc;
  77
  78         new_nsp->pid_ns = copy_pid_ns(flags, tsk->nsproxy->pid_ns);
  79         if (IS_ERR(new_nsp->pid_ns))
  80                 goto out_pid;
  81
  82         return new_nsp;
  83
  84 out_pid:
  85         if (new_nsp->ipc_ns)
  86                 put_ipc_ns(new_nsp->ipc_ns);
  87 out_ipc:
  88         if (new_nsp->uts_ns)
  89                 put_uts_ns(new_nsp->uts_ns);
  90 out_uts:
  91         if (new_nsp->mnt_ns)
  92                 put_mnt_ns(new_nsp->mnt_ns);
  93 out_ns:
  94         kfree(new_nsp);
  95         return ERR_PTR(-ENOMEM);
  96 }
  97
  98 /*
  99  * called from clone.  This now handles copy for nsproxy and all
 100  * namespaces therein.
 101  */
 102 int copy_namespaces(int flags, struct task_struct *tsk)
 103 {
 104         struct nsproxy *old_ns = tsk->nsproxy;
 105         struct nsproxy *new_ns;
 106         int err = 0;
 107
 108         if (!old_ns)
 109                 return 0;
 110
 111         get_nsproxy(old_ns);
 112
 113         if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC)))
 114                 return 0;
 115
 116         if (!capable(CAP_SYS_ADMIN)) {
 117                 err = -EPERM;
 118                 goto out;
 119         }
 120
 121         new_ns = create_new_namespaces(flags, tsk, tsk->fs);
 122         if (IS_ERR(new_ns)) {
 123                 err = PTR_ERR(new_ns);
 124                 goto out;
 125         }
 126
 127         tsk->nsproxy = new_ns;
 128 out:
 129         put_nsproxy(old_ns);
 130         return err;
 131 }
 132
 133 void free_nsproxy(struct nsproxy *ns)
 134 {
 135         if (ns->mnt_ns)
 136                 put_mnt_ns(ns->mnt_ns);
 137         if (ns->uts_ns)
 138                 put_uts_ns(ns->uts_ns);
 139         if (ns->ipc_ns)
 140                 put_ipc_ns(ns->ipc_ns);
 141         if (ns->pid_ns)
 142                 put_pid_ns(ns->pid_ns);
 143         kfree(ns);
 144 }
 145
 146 /*
 147  * Called from unshare. Unshare all the namespaces part of nsproxy.
 148  * On sucess, returns the new nsproxy and a reference to old nsproxy
 149  * to make sure it stays around.
 150  */
 151 int unshare_nsproxy_namespaces(unsigned long unshare_flags,
 152                 struct nsproxy **new_nsp, struct fs_struct *new_fs)
 153 {
 154         struct nsproxy *old_ns = current->nsproxy;
 155         int err = 0;
 156
 157         if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC)))
 158                 return 0;
 159
 160 #ifndef CONFIG_IPC_NS
 161         if (unshare_flags & CLONE_NEWIPC)
 162                 return -EINVAL;
 163 #endif
 164
 165 #ifndef CONFIG_UTS_NS
 166         if (unshare_flags & CLONE_NEWUTS)
 167                 return -EINVAL;
 168 #endif
 169
 170         if (!capable(CAP_SYS_ADMIN))
 171                 return -EPERM;
 172
 173         get_nsproxy(old_ns);
 174
 175         *new_nsp = create_new_namespaces(unshare_flags, current,
 176                                 new_fs ? new_fs : current->fs);
 177         if (IS_ERR(*new_nsp)) {
 178                 err = PTR_ERR(*new_nsp);
 179                 put_nsproxy(old_ns);
 180         }
 181         return err;
 182 }