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 static struct kmem_cache *nsproxy_cachep;
  25
  26 struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
  27
  28 static inline void get_nsproxy(struct nsproxy *ns)
  29 {
  30         atomic_inc(&ns->count);
  31 }
  32
  33 void get_task_namespaces(struct task_struct *tsk)
  34 {
  35         struct nsproxy *ns = tsk->nsproxy;
  36         if (ns) {
  37                 get_nsproxy(ns);
  38         }
  39 }
  40
  41 /*
  42  * creates a copy of "orig" with refcount 1.
  43  */
  44 static inline struct nsproxy *clone_nsproxy(struct nsproxy *orig)
  45 {
  46         struct nsproxy *ns;
  47
  48         ns = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL);
  49         if (ns) {
  50                 memcpy(ns, orig, sizeof(struct nsproxy));
  51                 atomic_set(&ns->count, 1);
  52         }
  53         return ns;
  54 }
  55
  56 /*
  57  * Create new nsproxy and all of its the associated namespaces.
  58  * Return the newly created nsproxy.  Do not attach this to the task,
  59  * leave it to the caller to do proper locking and attach it to task.
  60  */
  61 static struct nsproxy *create_new_namespaces(unsigned long flags,
  62                         struct task_struct *tsk, struct fs_struct *new_fs)
  63 {
  64         struct nsproxy *new_nsp;
  65         int err;
  66
  67         new_nsp = clone_nsproxy(tsk->nsproxy);
  68         if (!new_nsp)
  69                 return ERR_PTR(-ENOMEM);
  70
  71         new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, new_fs);
  72         if (IS_ERR(new_nsp->mnt_ns)) {
  73                 err = PTR_ERR(new_nsp->mnt_ns);
  74                 goto out_ns;
  75         }
  76
  77         new_nsp->uts_ns = copy_utsname(flags, tsk->nsproxy->uts_ns);
  78         if (IS_ERR(new_nsp->uts_ns)) {
  79                 err = PTR_ERR(new_nsp->uts_ns);
  80                 goto out_uts;
  81         }
  82
  83         new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns);
  84         if (IS_ERR(new_nsp->ipc_ns)) {
  85                 err = PTR_ERR(new_nsp->ipc_ns);
  86                 goto out_ipc;
  87         }
  88
  89         new_nsp->pid_ns = copy_pid_ns(flags, tsk->nsproxy->pid_ns);
  90         if (IS_ERR(new_nsp->pid_ns)) {
  91                 err = PTR_ERR(new_nsp->pid_ns);
  92                 goto out_pid;
  93         }
  94
  95         new_nsp->user_ns = copy_user_ns(flags, tsk->nsproxy->user_ns);
  96         if (IS_ERR(new_nsp->user_ns)) {
  97                 err = PTR_ERR(new_nsp->user_ns);
  98                 goto out_user;
  99         }
 100
 101         return new_nsp;
 102
 103 out_user:
 104         if (new_nsp->pid_ns)
 105                 put_pid_ns(new_nsp->pid_ns);
 106 out_pid:
 107         if (new_nsp->ipc_ns)
 108                 put_ipc_ns(new_nsp->ipc_ns);
 109 out_ipc:
 110         if (new_nsp->uts_ns)
 111                 put_uts_ns(new_nsp->uts_ns);
 112 out_uts:
 113         if (new_nsp->mnt_ns)
 114                 put_mnt_ns(new_nsp->mnt_ns);
 115 out_ns:
 116         kmem_cache_free(nsproxy_cachep, new_nsp);
 117         return ERR_PTR(err);
 118 }
 119
 120 /*
 121  * called from clone.  This now handles copy for nsproxy and all
 122  * namespaces therein.
 123  */
 124 int copy_namespaces(unsigned long flags, struct task_struct *tsk)
 125 {
 126         struct nsproxy *old_ns = tsk->nsproxy;
 127         struct nsproxy *new_ns;
 128         int err = 0;
 129
 130         if (!old_ns)
 131                 return 0;
 132
 133         get_nsproxy(old_ns);
 134
 135         if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | CLONE_NEWUSER)))
 136                 return 0;
 137
 138         if (!capable(CAP_SYS_ADMIN)) {
 139                 err = -EPERM;
 140                 goto out;
 141         }
 142
 143         new_ns = create_new_namespaces(flags, tsk, tsk->fs);
 144         if (IS_ERR(new_ns)) {
 145                 err = PTR_ERR(new_ns);
 146                 goto out;
 147         }
 148
 149         tsk->nsproxy = new_ns;
 150 out:
 151         put_nsproxy(old_ns);
 152         return err;
 153 }
 154
 155 void free_nsproxy(struct nsproxy *ns)
 156 {
 157         if (ns->mnt_ns)
 158                 put_mnt_ns(ns->mnt_ns);
 159         if (ns->uts_ns)
 160                 put_uts_ns(ns->uts_ns);
 161         if (ns->ipc_ns)
 162                 put_ipc_ns(ns->ipc_ns);
 163         if (ns->pid_ns)
 164                 put_pid_ns(ns->pid_ns);
 165         if (ns->user_ns)
 166                 put_user_ns(ns->user_ns);
 167         kmem_cache_free(nsproxy_cachep, ns);
 168 }
 169
 170 /*
 171  * Called from unshare. Unshare all the namespaces part of nsproxy.
 172  * On success, returns the new nsproxy.
 173  */
 174 int unshare_nsproxy_namespaces(unsigned long unshare_flags,
 175                 struct nsproxy **new_nsp, struct fs_struct *new_fs)
 176 {
 177         int err = 0;
 178
 179         if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 180                                CLONE_NEWUSER)))
 181                 return 0;
 182
 183         if (!capable(CAP_SYS_ADMIN))
 184                 return -EPERM;
 185
 186         *new_nsp = create_new_namespaces(unshare_flags, current,
 187                                 new_fs ? new_fs : current->fs);
 188         if (IS_ERR(*new_nsp))
 189                 err = PTR_ERR(*new_nsp);
 190         return err;
 191 }
 192
 193 static int __init nsproxy_cache_init(void)
 194 {
 195         nsproxy_cachep = kmem_cache_create("nsproxy", sizeof(struct nsproxy),
 196                                            0, SLAB_PANIC, NULL);
 197         return 0;
 198 }
 199
 200 module_init(nsproxy_cache_init);