net/core/net_namespace.c

   1 #include <linux/workqueue.h>
   2 #include <linux/rtnetlink.h>
   3 #include <linux/cache.h>
   4 #include <linux/slab.h>
   5 #include <linux/list.h>
   6 #include <linux/delay.h>
   7 #include <linux/sched.h>
   8 #include <net/net_namespace.h>
   9
  10 /*
  11  *      Our network namespace constructor/destructor lists
  12  */
  13
  14 static LIST_HEAD(pernet_list);
  15 static struct list_head *first_device = &pernet_list;
  16 static DEFINE_MUTEX(net_mutex);
  17
  18 LIST_HEAD(net_namespace_list);
  19
  20 static struct kmem_cache *net_cachep;
  21
  22 struct net init_net;
  23 EXPORT_SYMBOL_GPL(init_net);
  24
  25 static struct net *net_alloc(void)
  26 {
  27         return kmem_cache_zalloc(net_cachep, GFP_KERNEL);
  28 }
  29
  30 static void net_free(struct net *net)
  31 {
  32         if (!net)
  33                 return;
  34
  35         if (unlikely(atomic_read(&net->use_count) != 0)) {
  36                 printk(KERN_EMERG "network namespace not free! Usage: %d\n",
  37                         atomic_read(&net->use_count));
  38                 return;
  39         }
  40
  41         kmem_cache_free(net_cachep, net);
  42 }
  43
  44 static void cleanup_net(struct work_struct *work)
  45 {
  46         struct pernet_operations *ops;
  47         struct net *net;
  48
  49         net = container_of(work, struct net, work);
  50
  51         mutex_lock(&net_mutex);
  52
  53         /* Don't let anyone else find us. */
  54         rtnl_lock();
  55         list_del(&net->list);
  56         rtnl_unlock();
  57
  58         /* Run all of the network namespace exit methods */
  59         list_for_each_entry_reverse(ops, &pernet_list, list) {
  60                 if (ops->exit)
  61                         ops->exit(net);
  62         }
  63
  64         mutex_unlock(&net_mutex);
  65
  66         /* Ensure there are no outstanding rcu callbacks using this
  67          * network namespace.
  68          */
  69         rcu_barrier();
  70
  71         /* Finally it is safe to free my network namespace structure */
  72         net_free(net);
  73 }
  74
  75
  76 void __put_net(struct net *net)
  77 {
  78         /* Cleanup the network namespace in process context */
  79         INIT_WORK(&net->work, cleanup_net);
  80         schedule_work(&net->work);
  81 }
  82 EXPORT_SYMBOL_GPL(__put_net);
  83
  84 /*
  85  * setup_net runs the initializers for the network namespace object.
  86  */
  87 static int setup_net(struct net *net)
  88 {
  89         /* Must be called with net_mutex held */
  90         struct pernet_operations *ops;
  91         int error;
  92
  93         atomic_set(&net->count, 1);
  94         atomic_set(&net->use_count, 0);
  95
  96         error = 0;
  97         list_for_each_entry(ops, &pernet_list, list) {
  98                 if (ops->init) {
  99                         error = ops->init(net);
 100                         if (error < 0)
 101                                 goto out_undo;
 102                 }
 103         }
 104 out:
 105         return error;
 106
 107 out_undo:
 108         /* Walk through the list backwards calling the exit functions
 109          * for the pernet modules whose init functions did not fail.
 110          */
 111         list_for_each_entry_continue_reverse(ops, &pernet_list, list) {
 112                 if (ops->exit)
 113                         ops->exit(net);
 114         }
 115
 116         rcu_barrier();
 117         goto out;
 118 }
 119
 120 struct net *copy_net_ns(unsigned long flags, struct net *old_net)
 121 {
 122         struct net *new_net = NULL;
 123         int err;
 124
 125         get_net(old_net);
 126
 127         if (!(flags & CLONE_NEWNET))
 128                 return old_net;
 129
 130 #ifndef CONFIG_NET_NS
 131         return ERR_PTR(-EINVAL);
 132 #endif
 133
 134         err = -ENOMEM;
 135         new_net = net_alloc();
 136         if (!new_net)
 137                 goto out;
 138
 139         mutex_lock(&net_mutex);
 140         err = setup_net(new_net);
 141         if (err)
 142                 goto out_unlock;
 143
 144         rtnl_lock();
 145         list_add_tail(&new_net->list, &net_namespace_list);
 146         rtnl_unlock();
 147
 148
 149 out_unlock:
 150         mutex_unlock(&net_mutex);
 151 out:
 152         put_net(old_net);
 153         if (err) {
 154                 net_free(new_net);
 155                 new_net = ERR_PTR(err);
 156         }
 157         return new_net;
 158 }
 159
 160 static int __init net_ns_init(void)
 161 {
 162         int err;
 163
 164         printk(KERN_INFO "net_namespace: %zd bytes\n", sizeof(struct net));
 165         net_cachep = kmem_cache_create("net_namespace", sizeof(struct net),
 166                                         SMP_CACHE_BYTES,
 167                                         SLAB_PANIC, NULL);
 168         mutex_lock(&net_mutex);
 169         err = setup_net(&init_net);
 170
 171         rtnl_lock();
 172         list_add_tail(&init_net.list, &net_namespace_list);
 173         rtnl_unlock();
 174
 175         mutex_unlock(&net_mutex);
 176         if (err)
 177                 panic("Could not setup the initial network namespace");
 178
 179         return 0;
 180 }
 181
 182 pure_initcall(net_ns_init);
 183
 184 static int register_pernet_operations(struct list_head *list,
 185                                       struct pernet_operations *ops)
 186 {
 187         struct net *net, *undo_net;
 188         int error;
 189
 190         error = 0;
 191         list_add_tail(&ops->list, list);
 192         for_each_net(net) {
 193                 if (ops->init) {
 194                         error = ops->init(net);
 195                         if (error)
 196                                 goto out_undo;
 197                 }
 198         }
 199 out:
 200         return error;
 201
 202 out_undo:
 203         /* If I have an error cleanup all namespaces I initialized */
 204         list_del(&ops->list);
 205         for_each_net(undo_net) {
 206                 if (undo_net == net)
 207                         goto undone;
 208                 if (ops->exit)
 209                         ops->exit(undo_net);
 210         }
 211 undone:
 212         goto out;
 213 }
 214
 215 static void unregister_pernet_operations(struct pernet_operations *ops)
 216 {
 217         struct net *net;
 218
 219         list_del(&ops->list);
 220         for_each_net(net)
 221                 if (ops->exit)
 222                         ops->exit(net);
 223 }
 224
 225 /**
 226  *      register_pernet_subsys - register a network namespace subsystem
 227  *      @ops:  pernet operations structure for the subsystem
 228  *
 229  *      Register a subsystem which has init and exit functions
 230  *      that are called when network namespaces are created and
 231  *      destroyed respectively.
 232  *
 233  *      When registered all network namespace init functions are
 234  *      called for every existing network namespace.  Allowing kernel
 235  *      modules to have a race free view of the set of network namespaces.
 236  *
 237  *      When a new network namespace is created all of the init
 238  *      methods are called in the order in which they were registered.
 239  *
 240  *      When a network namespace is destroyed all of the exit methods
 241  *      are called in the reverse of the order with which they were
 242  *      registered.
 243  */
 244 int register_pernet_subsys(struct pernet_operations *ops)
 245 {
 246         int error;
 247         mutex_lock(&net_mutex);
 248         error =  register_pernet_operations(first_device, ops);
 249         mutex_unlock(&net_mutex);
 250         return error;
 251 }
 252 EXPORT_SYMBOL_GPL(register_pernet_subsys);
 253
 254 /**
 255  *      unregister_pernet_subsys - unregister a network namespace subsystem
 256  *      @ops: pernet operations structure to manipulate
 257  *
 258  *      Remove the pernet operations structure from the list to be
 259  *      used when network namespaces are created or destoryed.  In
 260  *      addition run the exit method for all existing network
 261  *      namespaces.
 262  */
 263 void unregister_pernet_subsys(struct pernet_operations *module)
 264 {
 265         mutex_lock(&net_mutex);
 266         unregister_pernet_operations(module);
 267         mutex_unlock(&net_mutex);
 268 }
 269 EXPORT_SYMBOL_GPL(unregister_pernet_subsys);
 270
 271 /**
 272  *      register_pernet_device - register a network namespace device
 273  *      @ops:  pernet operations structure for the subsystem
 274  *
 275  *      Register a device which has init and exit functions
 276  *      that are called when network namespaces are created and
 277  *      destroyed respectively.
 278  *
 279  *      When registered all network namespace init functions are
 280  *      called for every existing network namespace.  Allowing kernel
 281  *      modules to have a race free view of the set of network namespaces.
 282  *
 283  *      When a new network namespace is created all of the init
 284  *      methods are called in the order in which they were registered.
 285  *
 286  *      When a network namespace is destroyed all of the exit methods
 287  *      are called in the reverse of the order with which they were
 288  *      registered.
 289  */
 290 int register_pernet_device(struct pernet_operations *ops)
 291 {
 292         int error;
 293         mutex_lock(&net_mutex);
 294         error = register_pernet_operations(&pernet_list, ops);
 295         if (!error && (first_device == &pernet_list))
 296                 first_device = &ops->list;
 297         mutex_unlock(&net_mutex);
 298         return error;
 299 }
 300 EXPORT_SYMBOL_GPL(register_pernet_device);
 301
 302 /**
 303  *      unregister_pernet_device - unregister a network namespace netdevice
 304  *      @ops: pernet operations structure to manipulate
 305  *
 306  *      Remove the pernet operations structure from the list to be
 307  *      used when network namespaces are created or destoryed.  In
 308  *      addition run the exit method for all existing network
 309  *      namespaces.
 310  */
 311 void unregister_pernet_device(struct pernet_operations *ops)
 312 {
 313         mutex_lock(&net_mutex);
 314         if (&ops->list == first_device)
 315                 first_device = first_device->next;
 316         unregister_pernet_operations(ops);
 317         mutex_unlock(&net_mutex);
 318 }
 319 EXPORT_SYMBOL_GPL(unregister_pernet_device);