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         goto out;
 116 }
 117
 118 struct net *copy_net_ns(unsigned long flags, struct net *old_net)
 119 {
 120         struct net *new_net = NULL;
 121         int err;
 122
 123         get_net(old_net);
 124
 125         if (!(flags & CLONE_NEWNET))
 126                 return old_net;
 127
 128 #ifndef CONFIG_NET_NS
 129         return ERR_PTR(-EINVAL);
 130 #endif
 131
 132         err = -ENOMEM;
 133         new_net = net_alloc();
 134         if (!new_net)
 135                 goto out;
 136
 137         mutex_lock(&net_mutex);
 138         err = setup_net(new_net);
 139         if (err)
 140                 goto out_unlock;
 141
 142         rtnl_lock();
 143         list_add_tail(&new_net->list, &net_namespace_list);
 144         rtnl_unlock();
 145
 146
 147 out_unlock:
 148         mutex_unlock(&net_mutex);
 149 out:
 150         put_net(old_net);
 151         if (err) {
 152                 net_free(new_net);
 153                 new_net = ERR_PTR(err);
 154         }
 155         return new_net;
 156 }
 157
 158 static int __init net_ns_init(void)
 159 {
 160         int err;
 161
 162         printk(KERN_INFO "net_namespace: %zd bytes\n", sizeof(struct net));
 163         net_cachep = kmem_cache_create("net_namespace", sizeof(struct net),
 164                                         SMP_CACHE_BYTES,
 165                                         SLAB_PANIC, NULL);
 166         mutex_lock(&net_mutex);
 167         err = setup_net(&init_net);
 168
 169         rtnl_lock();
 170         list_add_tail(&init_net.list, &net_namespace_list);
 171         rtnl_unlock();
 172
 173         mutex_unlock(&net_mutex);
 174         if (err)
 175                 panic("Could not setup the initial network namespace");
 176
 177         return 0;
 178 }
 179
 180 pure_initcall(net_ns_init);
 181
 182 static int register_pernet_operations(struct list_head *list,
 183                                       struct pernet_operations *ops)
 184 {
 185         struct net *net, *undo_net;
 186         int error;
 187
 188         error = 0;
 189         list_add_tail(&ops->list, list);
 190         for_each_net(net) {
 191                 if (ops->init) {
 192                         error = ops->init(net);
 193                         if (error)
 194                                 goto out_undo;
 195                 }
 196         }
 197 out:
 198         return error;
 199
 200 out_undo:
 201         /* If I have an error cleanup all namespaces I initialized */
 202         list_del(&ops->list);
 203         for_each_net(undo_net) {
 204                 if (undo_net == net)
 205                         goto undone;
 206                 if (ops->exit)
 207                         ops->exit(undo_net);
 208         }
 209 undone:
 210         goto out;
 211 }
 212
 213 static void unregister_pernet_operations(struct pernet_operations *ops)
 214 {
 215         struct net *net;
 216
 217         list_del(&ops->list);
 218         for_each_net(net)
 219                 if (ops->exit)
 220                         ops->exit(net);
 221 }
 222
 223 /**
 224  *      register_pernet_subsys - register a network namespace subsystem
 225  *      @ops:  pernet operations structure for the subsystem
 226  *
 227  *      Register a subsystem which has init and exit functions
 228  *      that are called when network namespaces are created and
 229  *      destroyed respectively.
 230  *
 231  *      When registered all network namespace init functions are
 232  *      called for every existing network namespace.  Allowing kernel
 233  *      modules to have a race free view of the set of network namespaces.
 234  *
 235  *      When a new network namespace is created all of the init
 236  *      methods are called in the order in which they were registered.
 237  *
 238  *      When a network namespace is destroyed all of the exit methods
 239  *      are called in the reverse of the order with which they were
 240  *      registered.
 241  */
 242 int register_pernet_subsys(struct pernet_operations *ops)
 243 {
 244         int error;
 245         mutex_lock(&net_mutex);
 246         error =  register_pernet_operations(first_device, ops);
 247         mutex_unlock(&net_mutex);
 248         return error;
 249 }
 250 EXPORT_SYMBOL_GPL(register_pernet_subsys);
 251
 252 /**
 253  *      unregister_pernet_subsys - unregister a network namespace subsystem
 254  *      @ops: pernet operations structure to manipulate
 255  *
 256  *      Remove the pernet operations structure from the list to be
 257  *      used when network namespaces are created or destoryed.  In
 258  *      addition run the exit method for all existing network
 259  *      namespaces.
 260  */
 261 void unregister_pernet_subsys(struct pernet_operations *module)
 262 {
 263         mutex_lock(&net_mutex);
 264         unregister_pernet_operations(module);
 265         mutex_unlock(&net_mutex);
 266 }
 267 EXPORT_SYMBOL_GPL(unregister_pernet_subsys);
 268
 269 /**
 270  *      register_pernet_device - register a network namespace device
 271  *      @ops:  pernet operations structure for the subsystem
 272  *
 273  *      Register a device which has init and exit functions
 274  *      that are called when network namespaces are created and
 275  *      destroyed respectively.
 276  *
 277  *      When registered all network namespace init functions are
 278  *      called for every existing network namespace.  Allowing kernel
 279  *      modules to have a race free view of the set of network namespaces.
 280  *
 281  *      When a new network namespace is created all of the init
 282  *      methods are called in the order in which they were registered.
 283  *
 284  *      When a network namespace is destroyed all of the exit methods
 285  *      are called in the reverse of the order with which they were
 286  *      registered.
 287  */
 288 int register_pernet_device(struct pernet_operations *ops)
 289 {
 290         int error;
 291         mutex_lock(&net_mutex);
 292         error = register_pernet_operations(&pernet_list, ops);
 293         if (!error && (first_device == &pernet_list))
 294                 first_device = &ops->list;
 295         mutex_unlock(&net_mutex);
 296         return error;
 297 }
 298 EXPORT_SYMBOL_GPL(register_pernet_device);
 299
 300 /**
 301  *      unregister_pernet_device - unregister a network namespace netdevice
 302  *      @ops: pernet operations structure to manipulate
 303  *
 304  *      Remove the pernet operations structure from the list to be
 305  *      used when network namespaces are created or destoryed.  In
 306  *      addition run the exit method for all existing network
 307  *      namespaces.
 308  */
 309 void unregister_pernet_device(struct pernet_operations *ops)
 310 {
 311         mutex_lock(&net_mutex);
 312         if (&ops->list == first_device)
 313                 first_device = first_device->next;
 314         unregister_pernet_operations(ops);
 315         mutex_unlock(&net_mutex);
 316 }
 317 EXPORT_SYMBOL_GPL(unregister_pernet_device);