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 EXPORT_SYMBOL_GPL(net_namespace_list); 22 23 struct net init_net; 24 EXPORT_SYMBOL(init_net); 25 26 #define INITIAL_NET_GEN_PTRS 13 /* +1 for len +2 for rcu_head */ 27 28 /* 29 * setup_net runs the initializers for the network namespace object. 30 */ 31 static __net_init int setup_net(struct net *net) 32 { 33 /* Must be called with net_mutex held */ 34 struct pernet_operations *ops; 35 int error = 0; 36 37 atomic_set(&net->count, 1); 38 39 #ifdef NETNS_REFCNT_DEBUG 40 atomic_set(&net->use_count, 0); 41 #endif 42 43 list_for_each_entry(ops, &pernet_list, list) { 44 if (ops->init) { 45 error = ops->init(net); 46 if (error < 0) 47 goto out_undo; 48 } 49 } 50 out: 51 return error; 52 53 out_undo: 54 /* Walk through the list backwards calling the exit functions 55 * for the pernet modules whose init functions did not fail. 56 */ 57 list_for_each_entry_continue_reverse(ops, &pernet_list, list) { 58 if (ops->exit) 59 ops->exit(net); 60 } 61 62 rcu_barrier(); 63 goto out; 64 } 65 66 static struct net_generic *net_alloc_generic(void) 67 { 68 struct net_generic *ng; 69 size_t generic_size = sizeof(struct net_generic) + 70 INITIAL_NET_GEN_PTRS * sizeof(void *); 71 72 ng = kzalloc(generic_size, GFP_KERNEL); 73 if (ng) 74 ng->len = INITIAL_NET_GEN_PTRS; 75 76 return ng; 77 } 78 79 #ifdef CONFIG_NET_NS 80 static struct kmem_cache *net_cachep; 81 static struct workqueue_struct *netns_wq; 82 83 static struct net *net_alloc(void) 84 { 85 struct net *net = NULL; 86 struct net_generic *ng; 87 88 ng = net_alloc_generic(); 89 if (!ng) 90 goto out; 91 92 net = kmem_cache_zalloc(net_cachep, GFP_KERNEL); 93 if (!net) 94 goto out_free; 95 96 rcu_assign_pointer(net->gen, ng); 97 out: 98 return net; 99 100 out_free: 101 kfree(ng); 102 goto out; 103 } 104 105 static void net_free(struct net *net) 106 { 107 #ifdef NETNS_REFCNT_DEBUG 108 if (unlikely(atomic_read(&net->use_count) != 0)) { 109 printk(KERN_EMERG "network namespace not free! Usage: %d\n", 110 atomic_read(&net->use_count)); 111 return; 112 } 113 #endif 114 kfree(net->gen); 115 kmem_cache_free(net_cachep, net); 116 } 117 118 static struct net *net_create(void) 119 { 120 struct net *net; 121 int rv; 122 123 net = net_alloc(); 124 if (!net) 125 return ERR_PTR(-ENOMEM); 126 mutex_lock(&net_mutex); 127 rv = setup_net(net); 128 if (rv == 0) { 129 rtnl_lock(); 130 list_add_tail(&net->list, &net_namespace_list); 131 rtnl_unlock(); 132 } 133 mutex_unlock(&net_mutex); 134 if (rv < 0) { 135 net_free(net); 136 return ERR_PTR(rv); 137 } 138 return net; 139 } 140 141 struct net *copy_net_ns(unsigned long flags, struct net *old_net) 142 { 143 if (!(flags & CLONE_NEWNET)) 144 return get_net(old_net); 145 return net_create(); 146 } 147 148 static void cleanup_net(struct work_struct *work) 149 { 150 struct pernet_operations *ops; 151 struct net *net; 152 153 net = container_of(work, struct net, work); 154 155 mutex_lock(&net_mutex); 156 157 /* Don't let anyone else find us. */ 158 rtnl_lock(); 159 list_del(&net->list); 160 rtnl_unlock(); 161 162 /* Run all of the network namespace exit methods */ 163 list_for_each_entry_reverse(ops, &pernet_list, list) { 164 if (ops->exit) 165 ops->exit(net); 166 } 167 168 mutex_unlock(&net_mutex); 169 170 /* Ensure there are no outstanding rcu callbacks using this 171 * network namespace. 172 */ 173 rcu_barrier(); 174 175 /* Finally it is safe to free my network namespace structure */ 176 net_free(net); 177 } 178 179 void __put_net(struct net *net) 180 { 181 /* Cleanup the network namespace in process context */ 182 INIT_WORK(&net->work, cleanup_net); 183 queue_work(netns_wq, &net->work); 184 } 185 EXPORT_SYMBOL_GPL(__put_net); 186 187 #else 188 struct net *copy_net_ns(unsigned long flags, struct net *old_net) 189 { 190 if (flags & CLONE_NEWNET) 191 return ERR_PTR(-EINVAL); 192 return old_net; 193 } 194 #endif 195 196 static int __init net_ns_init(void) 197 { 198 struct net_generic *ng; 199 200 #ifdef CONFIG_NET_NS 201 net_cachep = kmem_cache_create("net_namespace", sizeof(struct net), 202 SMP_CACHE_BYTES, 203 SLAB_PANIC, NULL); 204 205 /* Create workqueue for cleanup */ 206 netns_wq = create_singlethread_workqueue("netns"); 207 if (!netns_wq) 208 panic("Could not create netns workq"); 209 #endif 210 211 ng = net_alloc_generic(); 212 if (!ng) 213 panic("Could not allocate generic netns"); 214 215 rcu_assign_pointer(init_net.gen, ng); 216 217 mutex_lock(&net_mutex); 218 if (setup_net(&init_net)) 219 panic("Could not setup the initial network namespace"); 220 221 rtnl_lock(); 222 list_add_tail(&init_net.list, &net_namespace_list); 223 rtnl_unlock(); 224 225 mutex_unlock(&net_mutex); 226 227 return 0; 228 } 229 230 pure_initcall(net_ns_init); 231 232 #ifdef CONFIG_NET_NS 233 static int register_pernet_operations(struct list_head *list, 234 struct pernet_operations *ops) 235 { 236 struct net *net, *undo_net; 237 int error; 238 239 list_add_tail(&ops->list, list); 240 if (ops->init) { 241 for_each_net(net) { 242 error = ops->init(net); 243 if (error) 244 goto out_undo; 245 } 246 } 247 return 0; 248 249 out_undo: 250 /* If I have an error cleanup all namespaces I initialized */ 251 list_del(&ops->list); 252 if (ops->exit) { 253 for_each_net(undo_net) { 254 if (undo_net == net) 255 goto undone; 256 ops->exit(undo_net); 257 } 258 } 259 undone: 260 return error; 261 } 262 263 static void unregister_pernet_operations(struct pernet_operations *ops) 264 { 265 struct net *net; 266 267 list_del(&ops->list); 268 if (ops->exit) 269 for_each_net(net) 270 ops->exit(net); 271 } 272 273 #else 274 275 static int register_pernet_operations(struct list_head *list, 276 struct pernet_operations *ops) 277 { 278 if (ops->init == NULL) 279 return 0; 280 return ops->init(&init_net); 281 } 282 283 static void unregister_pernet_operations(struct pernet_operations *ops) 284 { 285 if (ops->exit) 286 ops->exit(&init_net); 287 } 288 #endif 289 290 static DEFINE_IDA(net_generic_ids); 291 292 /** 293 * register_pernet_subsys - register a network namespace subsystem 294 * @ops: pernet operations structure for the subsystem 295 * 296 * Register a subsystem which has init and exit functions 297 * that are called when network namespaces are created and 298 * destroyed respectively. 299 * 300 * When registered all network namespace init functions are 301 * called for every existing network namespace. Allowing kernel 302 * modules to have a race free view of the set of network namespaces. 303 * 304 * When a new network namespace is created all of the init 305 * methods are called in the order in which they were registered. 306 * 307 * When a network namespace is destroyed all of the exit methods 308 * are called in the reverse of the order with which they were 309 * registered. 310 */ 311 int register_pernet_subsys(struct pernet_operations *ops) 312 { 313 int error; 314 mutex_lock(&net_mutex); 315 error = register_pernet_operations(first_device, ops); 316 mutex_unlock(&net_mutex); 317 return error; 318 } 319 EXPORT_SYMBOL_GPL(register_pernet_subsys); 320 321 /** 322 * unregister_pernet_subsys - unregister a network namespace subsystem 323 * @ops: pernet operations structure to manipulate 324 * 325 * Remove the pernet operations structure from the list to be 326 * used when network namespaces are created or destroyed. In 327 * addition run the exit method for all existing network 328 * namespaces. 329 */ 330 void unregister_pernet_subsys(struct pernet_operations *module) 331 { 332 mutex_lock(&net_mutex); 333 unregister_pernet_operations(module); 334 mutex_unlock(&net_mutex); 335 } 336 EXPORT_SYMBOL_GPL(unregister_pernet_subsys); 337 338 int register_pernet_gen_subsys(int *id, struct pernet_operations *ops) 339 { 340 int rv; 341 342 mutex_lock(&net_mutex); 343 again: 344 rv = ida_get_new_above(&net_generic_ids, 1, id); 345 if (rv < 0) { 346 if (rv == -EAGAIN) { 347 ida_pre_get(&net_generic_ids, GFP_KERNEL); 348 goto again; 349 } 350 goto out; 351 } 352 rv = register_pernet_operations(first_device, ops); 353 if (rv < 0) 354 ida_remove(&net_generic_ids, *id); 355 out: 356 mutex_unlock(&net_mutex); 357 return rv; 358 } 359 EXPORT_SYMBOL_GPL(register_pernet_gen_subsys); 360 361 void unregister_pernet_gen_subsys(int id, struct pernet_operations *ops) 362 { 363 mutex_lock(&net_mutex); 364 unregister_pernet_operations(ops); 365 ida_remove(&net_generic_ids, id); 366 mutex_unlock(&net_mutex); 367 } 368 EXPORT_SYMBOL_GPL(unregister_pernet_gen_subsys); 369 370 /** 371 * register_pernet_device - register a network namespace device 372 * @ops: pernet operations structure for the subsystem 373 * 374 * Register a device which has init and exit functions 375 * that are called when network namespaces are created and 376 * destroyed respectively. 377 * 378 * When registered all network namespace init functions are 379 * called for every existing network namespace. Allowing kernel 380 * modules to have a race free view of the set of network namespaces. 381 * 382 * When a new network namespace is created all of the init 383 * methods are called in the order in which they were registered. 384 * 385 * When a network namespace is destroyed all of the exit methods 386 * are called in the reverse of the order with which they were 387 * registered. 388 */ 389 int register_pernet_device(struct pernet_operations *ops) 390 { 391 int error; 392 mutex_lock(&net_mutex); 393 error = register_pernet_operations(&pernet_list, ops); 394 if (!error && (first_device == &pernet_list)) 395 first_device = &ops->list; 396 mutex_unlock(&net_mutex); 397 return error; 398 } 399 EXPORT_SYMBOL_GPL(register_pernet_device); 400 401 int register_pernet_gen_device(int *id, struct pernet_operations *ops) 402 { 403 int error; 404 mutex_lock(&net_mutex); 405 again: 406 error = ida_get_new_above(&net_generic_ids, 1, id); 407 if (error) { 408 if (error == -EAGAIN) { 409 ida_pre_get(&net_generic_ids, GFP_KERNEL); 410 goto again; 411 } 412 goto out; 413 } 414 error = register_pernet_operations(&pernet_list, ops); 415 if (error) 416 ida_remove(&net_generic_ids, *id); 417 else if (first_device == &pernet_list) 418 first_device = &ops->list; 419 out: 420 mutex_unlock(&net_mutex); 421 return error; 422 } 423 EXPORT_SYMBOL_GPL(register_pernet_gen_device); 424 425 /** 426 * unregister_pernet_device - unregister a network namespace netdevice 427 * @ops: pernet operations structure to manipulate 428 * 429 * Remove the pernet operations structure from the list to be 430 * used when network namespaces are created or destroyed. In 431 * addition run the exit method for all existing network 432 * namespaces. 433 */ 434 void unregister_pernet_device(struct pernet_operations *ops) 435 { 436 mutex_lock(&net_mutex); 437 if (&ops->list == first_device) 438 first_device = first_device->next; 439 unregister_pernet_operations(ops); 440 mutex_unlock(&net_mutex); 441 } 442 EXPORT_SYMBOL_GPL(unregister_pernet_device); 443 444 void unregister_pernet_gen_device(int id, struct pernet_operations *ops) 445 { 446 mutex_lock(&net_mutex); 447 if (&ops->list == first_device) 448 first_device = first_device->next; 449 unregister_pernet_operations(ops); 450 ida_remove(&net_generic_ids, id); 451 mutex_unlock(&net_mutex); 452 } 453 EXPORT_SYMBOL_GPL(unregister_pernet_gen_device); 454 455 static void net_generic_release(struct rcu_head *rcu) 456 { 457 struct net_generic *ng; 458 459 ng = container_of(rcu, struct net_generic, rcu); 460 kfree(ng); 461 } 462 463 int net_assign_generic(struct net *net, int id, void *data) 464 { 465 struct net_generic *ng, *old_ng; 466 467 BUG_ON(!mutex_is_locked(&net_mutex)); 468 BUG_ON(id == 0); 469 470 ng = old_ng = net->gen; 471 if (old_ng->len >= id) 472 goto assign; 473 474 ng = kzalloc(sizeof(struct net_generic) + 475 id * sizeof(void *), GFP_KERNEL); 476 if (ng == NULL) 477 return -ENOMEM; 478 479 /* 480 * Some synchronisation notes: 481 * 482 * The net_generic explores the net->gen array inside rcu 483 * read section. Besides once set the net->gen->ptr[x] 484 * pointer never changes (see rules in netns/generic.h). 485 * 486 * That said, we simply duplicate this array and schedule 487 * the old copy for kfree after a grace period. 488 */ 489 490 ng->len = id; 491 memcpy(&ng->ptr, &old_ng->ptr, old_ng->len * sizeof(void*)); 492 493 rcu_assign_pointer(net->gen, ng); 494 call_rcu(&old_ng->rcu, net_generic_release); 495 assign: 496 ng->ptr[id - 1] = data; 497 return 0; 498 } 499 EXPORT_SYMBOL_GPL(net_assign_generic); 500