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         int err;
  62
  63         new_nsp = clone_nsproxy(tsk->nsproxy);
  64         if (!new_nsp)
  65                 return ERR_PTR(-ENOMEM);
  66
  67         new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, new_fs);
  68         if (IS_ERR(new_nsp->mnt_ns)) {
  69                 err = PTR_ERR(new_nsp->mnt_ns);
  70                 goto out_ns;
  71         }
  72
  73         new_nsp->uts_ns = copy_utsname(flags, tsk->nsproxy->uts_ns);
  74         if (IS_ERR(new_nsp->uts_ns)) {
  75                 err = PTR_ERR(new_nsp->uts_ns);
  76                 goto out_uts;
  77         }
  78
  79         new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns);
  80         if (IS_ERR(new_nsp->ipc_ns)) {
  81                 err = PTR_ERR(new_nsp->ipc_ns);
  82                 goto out_ipc;
  83         }
  84
  85         new_nsp->pid_ns = copy_pid_ns(flags, tsk->nsproxy->pid_ns);
  86         if (IS_ERR(new_nsp->pid_ns)) {
  87                 err = PTR_ERR(new_nsp->pid_ns);
  88                 goto out_pid;
  89         }
  90
  91         new_nsp->user_ns = copy_user_ns(flags, tsk->nsproxy->user_ns);
  92         if (IS_ERR(new_nsp->user_ns)) {
  93                 err = PTR_ERR(new_nsp->user_ns);
  94                 goto out_user;
  95         }
  96
  97         return new_nsp;
  98
  99 out_user:
 100         if (new_nsp->pid_ns)
 101                 put_pid_ns(new_nsp->pid_ns);
 102 out_pid:
 103         if (new_nsp->ipc_ns)
 104                 put_ipc_ns(new_nsp->ipc_ns);
 105 out_ipc:
 106         if (new_nsp->uts_ns)
 107                 put_uts_ns(new_nsp->uts_ns);
 108 out_uts:
 109         if (new_nsp->mnt_ns)
 110                 put_mnt_ns(new_nsp->mnt_ns);
 111 out_ns:
 112         kfree(new_nsp);
 113         return ERR_PTR(err);
 114 }
 115
 116 /*
 117  * called from clone.  This now handles copy for nsproxy and all
 118  * namespaces therein.
 119  */
 120 int copy_namespaces(int flags, struct task_struct *tsk)
 121 {
 122         struct nsproxy *old_ns = tsk->nsproxy;
 123         struct nsproxy *new_ns;
 124         int err = 0;
 125
 126         if (!old_ns)
 127                 return 0;
 128
 129         get_nsproxy(old_ns);
 130
 131         if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | CLONE_NEWUSER)))
 132                 return 0;
 133
 134         if (!capable(CAP_SYS_ADMIN)) {
 135                 err = -EPERM;
 136                 goto out;
 137         }
 138
 139         new_ns = create_new_namespaces(flags, tsk, tsk->fs);
 140         if (IS_ERR(new_ns)) {
 141                 err = PTR_ERR(new_ns);
 142                 goto out;
 143         }
 144
 145         tsk->nsproxy = new_ns;
 146 out:
 147         put_nsproxy(old_ns);
 148         return err;
 149 }
 150
 151 void free_nsproxy(struct nsproxy *ns)
 152 {
 153         if (ns->mnt_ns)
 154                 put_mnt_ns(ns->mnt_ns);
 155         if (ns->uts_ns)
 156                 put_uts_ns(ns->uts_ns);
 157         if (ns->ipc_ns)
 158                 put_ipc_ns(ns->ipc_ns);
 159         if (ns->pid_ns)
 160                 put_pid_ns(ns->pid_ns);
 161         if (ns->user_ns)
 162                 put_user_ns(ns->user_ns);
 163         kfree(ns);
 164 }
 165
 166 /*
 167  * Called from unshare. Unshare all the namespaces part of nsproxy.
 168  * On success, returns the new nsproxy.
 169  */
 170 int unshare_nsproxy_namespaces(unsigned long unshare_flags,
 171                 struct nsproxy **new_nsp, struct fs_struct *new_fs)
 172 {
 173         int err = 0;
 174
 175         if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 176                                CLONE_NEWUSER)))
 177                 return 0;
 178
 179         if (!capable(CAP_SYS_ADMIN))
 180                 return -EPERM;
 181
 182         *new_nsp = create_new_namespaces(unshare_flags, current,
 183                                 new_fs ? new_fs : current->fs);
 184         if (IS_ERR(*new_nsp))
 185                 err = PTR_ERR(*new_nsp);
 186         return err;
 187 }