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 <linux/idr.h> 9 #include <net/net_namespace.h> 10 #include <net/netns/generic.h> 11 12 /* 13 * Our network namespace constructor/destructor lists 14 */ 15 16 static LIST_HEAD(pernet_list); 17 static struct list_head *first_device = &pernet_list; 18 static DEFINE_MUTEX(net_mutex); 19 20 LIST_HEAD(net_namespace_list); 21 22 struct net init_net; 23 EXPORT_SYMBOL(init_net); 24 25 #define INITIAL_NET_GEN_PTRS 13 /* +1 for len +2 for rcu_head */ 26 27 /* 28 * setup_net runs the initializers for the network namespace object. 29 */ 30 static __net_init int setup_net(struct net *net) 31 { 32 /* Must be called with net_mutex held */ 33 struct pernet_operations *ops; 34 int error; 35 struct net_generic *ng; 36 37 atomic_set(&net->count, 1); 38 #ifdef NETNS_REFCNT_DEBUG 39 atomic_set(&net->use_count, 0); 40 #endif 41 42 error = -ENOMEM; 43 ng = kzalloc(sizeof(struct net_generic) + 44 INITIAL_NET_GEN_PTRS * sizeof(void *), GFP_KERNEL); 45 if (ng == NULL) 46 goto out; 47 48 ng->len = INITIAL_NET_GEN_PTRS; 49 INIT_RCU_HEAD(&ng->rcu); 50 rcu_assign_pointer(net->gen, ng); 51 52 error = 0; 53 list_for_each_entry(ops, &pernet_list, list) { 54 if (ops->init) { 55 error = ops->init(net); 56 if (error < 0) 57 goto out_undo; 58 } 59 } 60 out: 61 return error; 62 63 out_undo: 64 /* Walk through the list backwards calling the exit functions 65 * for the pernet modules whose init functions did not fail. 66 */ 67 list_for_each_entry_continue_reverse(ops, &pernet_list, list) { 68 if (ops->exit) 69 ops->exit(net); 70 } 71 72 rcu_barrier(); 73 kfree(ng); 74 goto out; 75 } 76 77 #ifdef CONFIG_NET_NS 78 static struct kmem_cache *net_cachep; 79 static struct workqueue_struct *netns_wq; 80 81 static struct net *net_alloc(void) 82 { 83 return kmem_cache_zalloc(net_cachep, GFP_KERNEL); 84 } 85 86 static void net_free(struct net *net) 87 { 88 if (!net) 89 return; 90 91 #ifdef NETNS_REFCNT_DEBUG 92 if (unlikely(atomic_read(&net->use_count) != 0)) { 93 printk(KERN_EMERG "network namespace not free! Usage: %d\n", 94 atomic_read(&net->use_count)); 95 return; 96 } 97 #endif 98 99 kmem_cache_free(net_cachep, net); 100 } 101 102 struct net *copy_net_ns(unsigned long flags, struct net *old_net) 103 { 104 struct net *new_net = NULL; 105 int err; 106 107 get_net(old_net); 108 109 if (!(flags & CLONE_NEWNET)) 110 return old_net; 111 112 err = -ENOMEM; 113 new_net = net_alloc(); 114 if (!new_net) 115 goto out; 116 117 mutex_lock(&net_mutex); 118 err = setup_net(new_net); 119 if (err) 120 goto out_unlock; 121 122 rtnl_lock(); 123 list_add_tail(&new_net->list, &net_namespace_list); 124 rtnl_unlock(); 125 126 127 out_unlock: 128 mutex_unlock(&net_mutex); 129 out: 130 put_net(old_net); 131 if (err) { 132 net_free(new_net); 133 new_net = ERR_PTR(err); 134 } 135 return new_net; 136 } 137 138 static void cleanup_net(struct work_struct *work) 139 { 140 struct pernet_operations *ops; 141 struct net *net; 142 143 net = container_of(work, struct net, work); 144 145 mutex_lock(&net_mutex); 146 147 /* Don't let anyone else find us. */ 148 rtnl_lock(); 149 list_del(&net->list); 150 rtnl_unlock(); 151 152 /* Run all of the network namespace exit methods */ 153 list_for_each_entry_reverse(ops, &pernet_list, list) { 154 if (ops->exit) 155 ops->exit(net); 156 } 157 158 mutex_unlock(&net_mutex); 159 160 /* Ensure there are no outstanding rcu callbacks using this 161 * network namespace. 162 */ 163 rcu_barrier(); 164 165 /* Finally it is safe to free my network namespace structure */ 166 net_free(net); 167 } 168 169 void __put_net(struct net *net) 170 { 171 /* Cleanup the network namespace in process context */ 172 INIT_WORK(&net->work, cleanup_net); 173 queue_work(netns_wq, &net->work); 174 } 175 EXPORT_SYMBOL_GPL(__put_net); 176 177 #else 178 struct net *copy_net_ns(unsigned long flags, struct net *old_net) 179 { 180 if (flags & CLONE_NEWNET) 181 return ERR_PTR(-EINVAL); 182 return old_net; 183 } 184 #endif 185 186 static int __init net_ns_init(void) 187 { 188 int err; 189 190 printk(KERN_INFO "net_namespace: %zd bytes\n", sizeof(struct net)); 191 #ifdef CONFIG_NET_NS 192 net_cachep = kmem_cache_create("net_namespace", sizeof(struct net), 193 SMP_CACHE_BYTES, 194 SLAB_PANIC, NULL); 195 196 /* Create workqueue for cleanup */ 197 netns_wq = create_singlethread_workqueue("netns"); 198 if (!netns_wq) 199 panic("Could not create netns workq"); 200 #endif 201 202 mutex_lock(&net_mutex); 203 err = setup_net(&init_net); 204 205 rtnl_lock(); 206 list_add_tail(&init_net.list, &net_namespace_list); 207 rtnl_unlock(); 208 209 mutex_unlock(&net_mutex); 210 if (err) 211 panic("Could not setup the initial network namespace"); 212 213 return 0; 214 } 215 216 pure_initcall(net_ns_init); 217 218 #ifdef CONFIG_NET_NS 219 static int register_pernet_operations(struct list_head *list, 220 struct pernet_operations *ops) 221 { 222 struct net *net, *undo_net; 223 int error; 224 225 list_add_tail(&ops->list, list); 226 if (ops->init) { 227 for_each_net(net) { 228 error = ops->init(net); 229 if (error) 230 goto out_undo; 231 } 232 } 233 return 0; 234 235 out_undo: 236 /* If I have an error cleanup all namespaces I initialized */ 237 list_del(&ops->list); 238 if (ops->exit) { 239 for_each_net(undo_net) { 240 if (undo_net == net) 241 goto undone; 242 ops->exit(undo_net); 243 } 244 } 245 undone: 246 return error; 247 } 248 249 static void unregister_pernet_operations(struct pernet_operations *ops) 250 { 251 struct net *net; 252 253 list_del(&ops->list); 254 if (ops->exit) 255 for_each_net(net) 256 ops->exit(net); 257 } 258 259 #else 260 261 static int register_pernet_operations(struct list_head *list, 262 struct pernet_operations *ops) 263 { 264 if (ops->init == NULL) 265 return 0; 266 return ops->init(&init_net); 267 } 268 269 static void unregister_pernet_operations(struct pernet_operations *ops) 270 { 271 if (ops->exit) 272 ops->exit(&init_net); 273 } 274 #endif 275 276 static DEFINE_IDA(net_generic_ids); 277 278 /** 279 * register_pernet_subsys - register a network namespace subsystem 280 * @ops: pernet operations structure for the subsystem 281 * 282 * Register a subsystem which has init and exit functions 283 * that are called when network namespaces are created and 284 * destroyed respectively. 285 * 286 * When registered all network namespace init functions are 287 * called for every existing network namespace. Allowing kernel 288 * modules to have a race free view of the set of network namespaces. 289 * 290 * When a new network namespace is created all of the init 291 * methods are called in the order in which they were registered. 292 * 293 * When a network namespace is destroyed all of the exit methods 294 * are called in the reverse of the order with which they were 295 * registered. 296 */ 297 int register_pernet_subsys(struct pernet_operations *ops) 298 { 299 int error; 300 mutex_lock(&net_mutex); 301 error = register_pernet_operations(first_device, ops); 302 mutex_unlock(&net_mutex); 303 return error; 304 } 305 EXPORT_SYMBOL_GPL(register_pernet_subsys); 306 307 /** 308 * unregister_pernet_subsys - unregister a network namespace subsystem 309 * @ops: pernet operations structure to manipulate 310 * 311 * Remove the pernet operations structure from the list to be 312 * used when network namespaces are created or destroyed. In 313 * addition run the exit method for all existing network 314 * namespaces. 315 */ 316 void unregister_pernet_subsys(struct pernet_operations *module) 317 { 318 mutex_lock(&net_mutex); 319 unregister_pernet_operations(module); 320 mutex_unlock(&net_mutex); 321 } 322 EXPORT_SYMBOL_GPL(unregister_pernet_subsys); 323 324 /** 325 * register_pernet_device - register a network namespace device 326 * @ops: pernet operations structure for the subsystem 327 * 328 * Register a device which has init and exit functions 329 * that are called when network namespaces are created and 330 * destroyed respectively. 331 * 332 * When registered all network namespace init functions are 333 * called for every existing network namespace. Allowing kernel 334 * modules to have a race free view of the set of network namespaces. 335 * 336 * When a new network namespace is created all of the init 337 * methods are called in the order in which they were registered. 338 * 339 * When a network namespace is destroyed all of the exit methods 340 * are called in the reverse of the order with which they were 341 * registered. 342 */ 343 int register_pernet_device(struct pernet_operations *ops) 344 { 345 int error; 346 mutex_lock(&net_mutex); 347 error = register_pernet_operations(&pernet_list, ops); 348 if (!error && (first_device == &pernet_list)) 349 first_device = &ops->list; 350 mutex_unlock(&net_mutex); 351 return error; 352 } 353 EXPORT_SYMBOL_GPL(register_pernet_device); 354 355 int register_pernet_gen_device(int *id, struct pernet_operations *ops) 356 { 357 int error; 358 mutex_lock(&net_mutex); 359 again: 360 error = ida_get_new_above(&net_generic_ids, 1, id); 361 if (error) { 362 if (error == -EAGAIN) { 363 ida_pre_get(&net_generic_ids, GFP_KERNEL); 364 goto again; 365 } 366 goto out; 367 } 368 error = register_pernet_operations(&pernet_list, ops); 369 if (error) 370 ida_remove(&net_generic_ids, *id); 371 else if (first_device == &pernet_list) 372 first_device = &ops->list; 373 out: 374 mutex_unlock(&net_mutex); 375 return error; 376 } 377 EXPORT_SYMBOL_GPL(register_pernet_gen_device); 378 379 /** 380 * unregister_pernet_device - unregister a network namespace netdevice 381 * @ops: pernet operations structure to manipulate 382 * 383 * Remove the pernet operations structure from the list to be 384 * used when network namespaces are created or destroyed. In 385 * addition run the exit method for all existing network 386 * namespaces. 387 */ 388 void unregister_pernet_device(struct pernet_operations *ops) 389 { 390 mutex_lock(&net_mutex); 391 if (&ops->list == first_device) 392 first_device = first_device->next; 393 unregister_pernet_operations(ops); 394 mutex_unlock(&net_mutex); 395 } 396 EXPORT_SYMBOL_GPL(unregister_pernet_device); 397 398 void unregister_pernet_gen_device(int id, struct pernet_operations *ops) 399 { 400 mutex_lock(&net_mutex); 401 if (&ops->list == first_device) 402 first_device = first_device->next; 403 unregister_pernet_operations(ops); 404 ida_remove(&net_generic_ids, id); 405 mutex_unlock(&net_mutex); 406 } 407 EXPORT_SYMBOL_GPL(unregister_pernet_gen_device); 408 409 static void net_generic_release(struct rcu_head *rcu) 410 { 411 struct net_generic *ng; 412 413 ng = container_of(rcu, struct net_generic, rcu); 414 kfree(ng); 415 } 416 417 int net_assign_generic(struct net *net, int id, void *data) 418 { 419 struct net_generic *ng, *old_ng; 420 421 BUG_ON(!mutex_is_locked(&net_mutex)); 422 BUG_ON(id == 0); 423 424 ng = old_ng = net->gen; 425 if (old_ng->len >= id) 426 goto assign; 427 428 ng = kzalloc(sizeof(struct net_generic) + 429 id * sizeof(void *), GFP_KERNEL); 430 if (ng == NULL) 431 return -ENOMEM; 432 433 /* 434 * Some synchronisation notes: 435 * 436 * The net_generic explores the net->gen array inside rcu 437 * read section. Besides once set the net->gen->ptr[x] 438 * pointer never changes (see rules in netns/generic.h). 439 * 440 * That said, we simply duplicate this array and schedule 441 * the old copy for kfree after a grace period. 442 */ 443 444 ng->len = id; 445 INIT_RCU_HEAD(&ng->rcu); 446 memcpy(&ng->ptr, &old_ng->ptr, old_ng->len); 447 448 rcu_assign_pointer(net->gen, ng); 449 call_rcu(&old_ng->rcu, net_generic_release); 450 assign: 451 ng->ptr[id - 1] = data; 452 return 0; 453 } 454 EXPORT_SYMBOL_GPL(net_assign_generic); 455