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 /* Be very certain incoming network packets will not find us */ 144 rcu_barrier(); 145 146 net = container_of(work, struct net, work); 147 148 mutex_lock(&net_mutex); 149 150 /* Don't let anyone else find us. */ 151 rtnl_lock(); 152 list_del(&net->list); 153 rtnl_unlock(); 154 155 /* Run all of the network namespace exit methods */ 156 list_for_each_entry_reverse(ops, &pernet_list, list) { 157 if (ops->exit) 158 ops->exit(net); 159 } 160 161 mutex_unlock(&net_mutex); 162 163 /* Ensure there are no outstanding rcu callbacks using this 164 * network namespace. 165 */ 166 rcu_barrier(); 167 168 /* Finally it is safe to free my network namespace structure */ 169 net_free(net); 170 } 171 172 void __put_net(struct net *net) 173 { 174 /* Cleanup the network namespace in process context */ 175 INIT_WORK(&net->work, cleanup_net); 176 queue_work(netns_wq, &net->work); 177 } 178 EXPORT_SYMBOL_GPL(__put_net); 179 180 #else 181 struct net *copy_net_ns(unsigned long flags, struct net *old_net) 182 { 183 if (flags & CLONE_NEWNET) 184 return ERR_PTR(-EINVAL); 185 return old_net; 186 } 187 #endif 188 189 static int __init net_ns_init(void) 190 { 191 int err; 192 193 printk(KERN_INFO "net_namespace: %zd bytes\n", sizeof(struct net)); 194 #ifdef CONFIG_NET_NS 195 net_cachep = kmem_cache_create("net_namespace", sizeof(struct net), 196 SMP_CACHE_BYTES, 197 SLAB_PANIC, NULL); 198 199 /* Create workqueue for cleanup */ 200 netns_wq = create_singlethread_workqueue("netns"); 201 if (!netns_wq) 202 panic("Could not create netns workq"); 203 #endif 204 205 mutex_lock(&net_mutex); 206 err = setup_net(&init_net); 207 208 rtnl_lock(); 209 list_add_tail(&init_net.list, &net_namespace_list); 210 rtnl_unlock(); 211 212 mutex_unlock(&net_mutex); 213 if (err) 214 panic("Could not setup the initial network namespace"); 215 216 return 0; 217 } 218 219 pure_initcall(net_ns_init); 220 221 #ifdef CONFIG_NET_NS 222 static int register_pernet_operations(struct list_head *list, 223 struct pernet_operations *ops) 224 { 225 struct net *net, *undo_net; 226 int error; 227 228 list_add_tail(&ops->list, list); 229 if (ops->init) { 230 for_each_net(net) { 231 error = ops->init(net); 232 if (error) 233 goto out_undo; 234 } 235 } 236 return 0; 237 238 out_undo: 239 /* If I have an error cleanup all namespaces I initialized */ 240 list_del(&ops->list); 241 if (ops->exit) { 242 for_each_net(undo_net) { 243 if (undo_net == net) 244 goto undone; 245 ops->exit(undo_net); 246 } 247 } 248 undone: 249 return error; 250 } 251 252 static void unregister_pernet_operations(struct pernet_operations *ops) 253 { 254 struct net *net; 255 256 list_del(&ops->list); 257 if (ops->exit) 258 for_each_net(net) 259 ops->exit(net); 260 } 261 262 #else 263 264 static int register_pernet_operations(struct list_head *list, 265 struct pernet_operations *ops) 266 { 267 if (ops->init == NULL) 268 return 0; 269 return ops->init(&init_net); 270 } 271 272 static void unregister_pernet_operations(struct pernet_operations *ops) 273 { 274 if (ops->exit) 275 ops->exit(&init_net); 276 } 277 #endif 278 279 static DEFINE_IDA(net_generic_ids); 280 281 /** 282 * register_pernet_subsys - register a network namespace subsystem 283 * @ops: pernet operations structure for the subsystem 284 * 285 * Register a subsystem which has init and exit functions 286 * that are called when network namespaces are created and 287 * destroyed respectively. 288 * 289 * When registered all network namespace init functions are 290 * called for every existing network namespace. Allowing kernel 291 * modules to have a race free view of the set of network namespaces. 292 * 293 * When a new network namespace is created all of the init 294 * methods are called in the order in which they were registered. 295 * 296 * When a network namespace is destroyed all of the exit methods 297 * are called in the reverse of the order with which they were 298 * registered. 299 */ 300 int register_pernet_subsys(struct pernet_operations *ops) 301 { 302 int error; 303 mutex_lock(&net_mutex); 304 error = register_pernet_operations(first_device, ops); 305 mutex_unlock(&net_mutex); 306 return error; 307 } 308 EXPORT_SYMBOL_GPL(register_pernet_subsys); 309 310 /** 311 * unregister_pernet_subsys - unregister a network namespace subsystem 312 * @ops: pernet operations structure to manipulate 313 * 314 * Remove the pernet operations structure from the list to be 315 * used when network namespaces are created or destroyed. In 316 * addition run the exit method for all existing network 317 * namespaces. 318 */ 319 void unregister_pernet_subsys(struct pernet_operations *module) 320 { 321 mutex_lock(&net_mutex); 322 unregister_pernet_operations(module); 323 mutex_unlock(&net_mutex); 324 } 325 EXPORT_SYMBOL_GPL(unregister_pernet_subsys); 326 327 /** 328 * register_pernet_device - register a network namespace device 329 * @ops: pernet operations structure for the subsystem 330 * 331 * Register a device which has init and exit functions 332 * that are called when network namespaces are created and 333 * destroyed respectively. 334 * 335 * When registered all network namespace init functions are 336 * called for every existing network namespace. Allowing kernel 337 * modules to have a race free view of the set of network namespaces. 338 * 339 * When a new network namespace is created all of the init 340 * methods are called in the order in which they were registered. 341 * 342 * When a network namespace is destroyed all of the exit methods 343 * are called in the reverse of the order with which they were 344 * registered. 345 */ 346 int register_pernet_device(struct pernet_operations *ops) 347 { 348 int error; 349 mutex_lock(&net_mutex); 350 error = register_pernet_operations(&pernet_list, ops); 351 if (!error && (first_device == &pernet_list)) 352 first_device = &ops->list; 353 mutex_unlock(&net_mutex); 354 return error; 355 } 356 EXPORT_SYMBOL_GPL(register_pernet_device); 357 358 int register_pernet_gen_device(int *id, struct pernet_operations *ops) 359 { 360 int error; 361 mutex_lock(&net_mutex); 362 again: 363 error = ida_get_new_above(&net_generic_ids, 1, id); 364 if (error) { 365 if (error == -EAGAIN) { 366 ida_pre_get(&net_generic_ids, GFP_KERNEL); 367 goto again; 368 } 369 goto out; 370 } 371 error = register_pernet_operations(&pernet_list, ops); 372 if (error) 373 ida_remove(&net_generic_ids, *id); 374 else if (first_device == &pernet_list) 375 first_device = &ops->list; 376 out: 377 mutex_unlock(&net_mutex); 378 return error; 379 } 380 EXPORT_SYMBOL_GPL(register_pernet_gen_device); 381 382 /** 383 * unregister_pernet_device - unregister a network namespace netdevice 384 * @ops: pernet operations structure to manipulate 385 * 386 * Remove the pernet operations structure from the list to be 387 * used when network namespaces are created or destroyed. In 388 * addition run the exit method for all existing network 389 * namespaces. 390 */ 391 void unregister_pernet_device(struct pernet_operations *ops) 392 { 393 mutex_lock(&net_mutex); 394 if (&ops->list == first_device) 395 first_device = first_device->next; 396 unregister_pernet_operations(ops); 397 mutex_unlock(&net_mutex); 398 } 399 EXPORT_SYMBOL_GPL(unregister_pernet_device); 400 401 void unregister_pernet_gen_device(int id, struct pernet_operations *ops) 402 { 403 mutex_lock(&net_mutex); 404 if (&ops->list == first_device) 405 first_device = first_device->next; 406 unregister_pernet_operations(ops); 407 ida_remove(&net_generic_ids, id); 408 mutex_unlock(&net_mutex); 409 } 410 EXPORT_SYMBOL_GPL(unregister_pernet_gen_device); 411 412 static void net_generic_release(struct rcu_head *rcu) 413 { 414 struct net_generic *ng; 415 416 ng = container_of(rcu, struct net_generic, rcu); 417 kfree(ng); 418 } 419 420 int net_assign_generic(struct net *net, int id, void *data) 421 { 422 struct net_generic *ng, *old_ng; 423 424 BUG_ON(!mutex_is_locked(&net_mutex)); 425 BUG_ON(id == 0); 426 427 ng = old_ng = net->gen; 428 if (old_ng->len >= id) 429 goto assign; 430 431 ng = kzalloc(sizeof(struct net_generic) + 432 id * sizeof(void *), GFP_KERNEL); 433 if (ng == NULL) 434 return -ENOMEM; 435 436 /* 437 * Some synchronisation notes: 438 * 439 * The net_generic explores the net->gen array inside rcu 440 * read section. Besides once set the net->gen->ptr[x] 441 * pointer never changes (see rules in netns/generic.h). 442 * 443 * That said, we simply duplicate this array and schedule 444 * the old copy for kfree after a grace period. 445 */ 446 447 ng->len = id; 448 INIT_RCU_HEAD(&ng->rcu); 449 memcpy(&ng->ptr, &old_ng->ptr, old_ng->len); 450 451 rcu_assign_pointer(net->gen, ng); 452 call_rcu(&old_ng->rcu, net_generic_release); 453 assign: 454 ng->ptr[id - 1] = data; 455 return 0; 456 } 457 EXPORT_SYMBOL_GPL(net_assign_generic); 458