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 <linux/idr.h>
   9 #include <linux/rculist.h>
  10 #include <linux/nsproxy.h>
  11 #include <linux/proc_fs.h>
  12 #include <linux/file.h>
  13 #include <net/net_namespace.h>
  14 #include <net/netns/generic.h>
  15
  16 /*
  17  *      Our network namespace constructor/destructor lists
  18  */
  19
  20 static LIST_HEAD(pernet_list);
  21 static struct list_head *first_device = &pernet_list;
  22 static DEFINE_MUTEX(net_mutex);
  23
  24 LIST_HEAD(net_namespace_list);
  25 EXPORT_SYMBOL_GPL(net_namespace_list);
  26
  27 struct net init_net;
  28 EXPORT_SYMBOL(init_net);
  29
  30 #define INITIAL_NET_GEN_PTRS    13 /* +1 for len +2 for rcu_head */
  31
  32 static int net_assign_generic(struct net *net, int id, void *data)
  33 {
  34         struct net_generic *ng, *old_ng;
  35
  36         BUG_ON(!mutex_is_locked(&net_mutex));
  37         BUG_ON(id == 0);
  38
  39         old_ng = rcu_dereference_protected(net->gen,
  40                                            lockdep_is_held(&net_mutex));
  41         ng = old_ng;
  42         if (old_ng->len >= id)
  43                 goto assign;
  44
  45         ng = kzalloc(sizeof(struct net_generic) +
  46                         id * sizeof(void *), GFP_KERNEL);
  47         if (ng == NULL)
  48                 return -ENOMEM;
  49
  50         /*
  51          * Some synchronisation notes:
  52          *
  53          * The net_generic explores the net->gen array inside rcu
  54          * read section. Besides once set the net->gen->ptr[x]
  55          * pointer never changes (see rules in netns/generic.h).
  56          *
  57          * That said, we simply duplicate this array and schedule
  58          * the old copy for kfree after a grace period.
  59          */
  60
  61         ng->len = id;
  62         memcpy(&ng->ptr, &old_ng->ptr, old_ng->len * sizeof(void*));
  63
  64         rcu_assign_pointer(net->gen, ng);
  65         kfree_rcu(old_ng, rcu);
  66 assign:
  67         ng->ptr[id - 1] = data;
  68         return 0;
  69 }
  70
  71 static int ops_init(const struct pernet_operations *ops, struct net *net)
  72 {
  73         int err;
  74         if (ops->id && ops->size) {
  75                 void *data = kzalloc(ops->size, GFP_KERNEL);
  76                 if (!data)
  77                         return -ENOMEM;
  78
  79                 err = net_assign_generic(net, *ops->id, data);
  80                 if (err) {
  81                         kfree(data);
  82                         return err;
  83                 }
  84         }
  85         if (ops->init)
  86                 return ops->init(net);
  87         return 0;
  88 }
  89
  90 static void ops_free(const struct pernet_operations *ops, struct net *net)
  91 {
  92         if (ops->id && ops->size) {
  93                 int id = *ops->id;
  94                 kfree(net_generic(net, id));
  95         }
  96 }
  97
  98 static void ops_exit_list(const struct pernet_operations *ops,
  99                           struct list_head *net_exit_list)
 100 {
 101         struct net *net;
 102         if (ops->exit) {
 103                 list_for_each_entry(net, net_exit_list, exit_list)
 104                         ops->exit(net);
 105         }
 106         if (ops->exit_batch)
 107                 ops->exit_batch(net_exit_list);
 108 }
 109
 110 static void ops_free_list(const struct pernet_operations *ops,
 111                           struct list_head *net_exit_list)
 112 {
 113         struct net *net;
 114         if (ops->size && ops->id) {
 115                 list_for_each_entry(net, net_exit_list, exit_list)
 116                         ops_free(ops, net);
 117         }
 118 }
 119
 120 /*
 121  * setup_net runs the initializers for the network namespace object.
 122  */
 123 static __net_init int setup_net(struct net *net)
 124 {
 125         /* Must be called with net_mutex held */
 126         const struct pernet_operations *ops, *saved_ops;
 127         int error = 0;
 128         LIST_HEAD(net_exit_list);
 129
 130         atomic_set(&net->count, 1);
 131
 132 #ifdef NETNS_REFCNT_DEBUG
 133         atomic_set(&net->use_count, 0);
 134 #endif
 135
 136         list_for_each_entry(ops, &pernet_list, list) {
 137                 error = ops_init(ops, net);
 138                 if (error < 0)
 139                         goto out_undo;
 140         }
 141 out:
 142         return error;
 143
 144 out_undo:
 145         /* Walk through the list backwards calling the exit functions
 146          * for the pernet modules whose init functions did not fail.
 147          */
 148         list_add(&net->exit_list, &net_exit_list);
 149         saved_ops = ops;
 150         list_for_each_entry_continue_reverse(ops, &pernet_list, list)
 151                 ops_exit_list(ops, &net_exit_list);
 152
 153         ops = saved_ops;
 154         list_for_each_entry_continue_reverse(ops, &pernet_list, list)
 155                 ops_free_list(ops, &net_exit_list);
 156
 157         rcu_barrier();
 158         goto out;
 159 }
 160
 161 static struct net_generic *net_alloc_generic(void)
 162 {
 163         struct net_generic *ng;
 164         size_t generic_size = sizeof(struct net_generic) +
 165                 INITIAL_NET_GEN_PTRS * sizeof(void *);
 166
 167         ng = kzalloc(generic_size, GFP_KERNEL);
 168         if (ng)
 169                 ng->len = INITIAL_NET_GEN_PTRS;
 170
 171         return ng;
 172 }
 173
 174 #ifdef CONFIG_NET_NS
 175 static struct kmem_cache *net_cachep;
 176 static struct workqueue_struct *netns_wq;
 177
 178 static struct net *net_alloc(void)
 179 {
 180         struct net *net = NULL;
 181         struct net_generic *ng;
 182
 183         ng = net_alloc_generic();
 184         if (!ng)
 185                 goto out;
 186
 187         net = kmem_cache_zalloc(net_cachep, GFP_KERNEL);
 188         if (!net)
 189                 goto out_free;
 190
 191         rcu_assign_pointer(net->gen, ng);
 192 out:
 193         return net;
 194
 195 out_free:
 196         kfree(ng);
 197         goto out;
 198 }
 199
 200 static void net_free(struct net *net)
 201 {
 202 #ifdef NETNS_REFCNT_DEBUG
 203         if (unlikely(atomic_read(&net->use_count) != 0)) {
 204                 printk(KERN_EMERG "network namespace not free! Usage: %d\n",
 205                         atomic_read(&net->use_count));
 206                 return;
 207         }
 208 #endif
 209         kfree(net->gen);
 210         kmem_cache_free(net_cachep, net);
 211 }
 212
 213 struct net *copy_net_ns(unsigned long flags, struct net *old_net)
 214 {
 215         struct net *net;
 216         int rv;
 217
 218         if (!(flags & CLONE_NEWNET))
 219                 return get_net(old_net);
 220
 221         net = net_alloc();
 222         if (!net)
 223                 return ERR_PTR(-ENOMEM);
 224         mutex_lock(&net_mutex);
 225         rv = setup_net(net);
 226         if (rv == 0) {
 227                 rtnl_lock();
 228                 list_add_tail_rcu(&net->list, &net_namespace_list);
 229                 rtnl_unlock();
 230         }
 231         mutex_unlock(&net_mutex);
 232         if (rv < 0) {
 233                 net_free(net);
 234                 return ERR_PTR(rv);
 235         }
 236         return net;
 237 }
 238
 239 static DEFINE_SPINLOCK(cleanup_list_lock);
 240 static LIST_HEAD(cleanup_list);  /* Must hold cleanup_list_lock to touch */
 241
 242 static void cleanup_net(struct work_struct *work)
 243 {
 244         const struct pernet_operations *ops;
 245         struct net *net, *tmp;
 246         LIST_HEAD(net_kill_list);
 247         LIST_HEAD(net_exit_list);
 248
 249         /* Atomically snapshot the list of namespaces to cleanup */
 250         spin_lock_irq(&cleanup_list_lock);
 251         list_replace_init(&cleanup_list, &net_kill_list);
 252         spin_unlock_irq(&cleanup_list_lock);
 253
 254         mutex_lock(&net_mutex);
 255
 256         /* Don't let anyone else find us. */
 257         rtnl_lock();
 258         list_for_each_entry(net, &net_kill_list, cleanup_list) {
 259                 list_del_rcu(&net->list);
 260                 list_add_tail(&net->exit_list, &net_exit_list);
 261         }
 262         rtnl_unlock();
 263
 264         /*
 265          * Another CPU might be rcu-iterating the list, wait for it.
 266          * This needs to be before calling the exit() notifiers, so
 267          * the rcu_barrier() below isn't sufficient alone.
 268          */
 269         synchronize_rcu();
 270
 271         /* Run all of the network namespace exit methods */
 272         list_for_each_entry_reverse(ops, &pernet_list, list)
 273                 ops_exit_list(ops, &net_exit_list);
 274
 275         /* Free the net generic variables */
 276         list_for_each_entry_reverse(ops, &pernet_list, list)
 277                 ops_free_list(ops, &net_exit_list);
 278
 279         mutex_unlock(&net_mutex);
 280
 281         /* Ensure there are no outstanding rcu callbacks using this
 282          * network namespace.
 283          */
 284         rcu_barrier();
 285
 286         /* Finally it is safe to free my network namespace structure */
 287         list_for_each_entry_safe(net, tmp, &net_exit_list, exit_list) {
 288                 list_del_init(&net->exit_list);
 289                 net_free(net);
 290         }
 291 }
 292 static DECLARE_WORK(net_cleanup_work, cleanup_net);
 293
 294 void __put_net(struct net *net)
 295 {
 296         /* Cleanup the network namespace in process context */
 297         unsigned long flags;
 298
 299         spin_lock_irqsave(&cleanup_list_lock, flags);
 300         list_add(&net->cleanup_list, &cleanup_list);
 301         spin_unlock_irqrestore(&cleanup_list_lock, flags);
 302
 303         queue_work(netns_wq, &net_cleanup_work);
 304 }
 305 EXPORT_SYMBOL_GPL(__put_net);
 306
 307 struct net *get_net_ns_by_fd(int fd)
 308 {
 309         struct proc_inode *ei;
 310         struct file *file;
 311         struct net *net;
 312
 313         net = ERR_PTR(-EINVAL);
 314         file = proc_ns_fget(fd);
 315         if (!file)
 316                 goto out;
 317
 318         ei = PROC_I(file->f_dentry->d_inode);
 319         if (ei->ns_ops != &netns_operations)
 320                 goto out;
 321
 322         net = get_net(ei->ns);
 323 out:
 324         if (file)
 325                 fput(file);
 326         return net;
 327 }
 328
 329 #else
 330 struct net *copy_net_ns(unsigned long flags, struct net *old_net)
 331 {
 332         if (flags & CLONE_NEWNET)
 333                 return ERR_PTR(-EINVAL);
 334         return old_net;
 335 }
 336
 337 struct net *get_net_ns_by_fd(int fd)
 338 {
 339         return ERR_PTR(-EINVAL);
 340 }
 341 #endif
 342
 343 struct net *get_net_ns_by_pid(pid_t pid)
 344 {
 345         struct task_struct *tsk;
 346         struct net *net;
 347
 348         /* Lookup the network namespace */
 349         net = ERR_PTR(-ESRCH);
 350         rcu_read_lock();
 351         tsk = find_task_by_vpid(pid);
 352         if (tsk) {
 353                 struct nsproxy *nsproxy;
 354                 nsproxy = task_nsproxy(tsk);
 355                 if (nsproxy)
 356                         net = get_net(nsproxy->net_ns);
 357         }
 358         rcu_read_unlock();
 359         return net;
 360 }
 361 EXPORT_SYMBOL_GPL(get_net_ns_by_pid);
 362
 363 static int __init net_ns_init(void)
 364 {
 365         struct net_generic *ng;
 366
 367 #ifdef CONFIG_NET_NS
 368         net_cachep = kmem_cache_create("net_namespace", sizeof(struct net),
 369                                         SMP_CACHE_BYTES,
 370                                         SLAB_PANIC, NULL);
 371
 372         /* Create workqueue for cleanup */
 373         netns_wq = create_singlethread_workqueue("netns");
 374         if (!netns_wq)
 375                 panic("Could not create netns workq");
 376 #endif
 377
 378         ng = net_alloc_generic();
 379         if (!ng)
 380                 panic("Could not allocate generic netns");
 381
 382         rcu_assign_pointer(init_net.gen, ng);
 383
 384         mutex_lock(&net_mutex);
 385         if (setup_net(&init_net))
 386                 panic("Could not setup the initial network namespace");
 387
 388         rtnl_lock();
 389         list_add_tail_rcu(&init_net.list, &net_namespace_list);
 390         rtnl_unlock();
 391
 392         mutex_unlock(&net_mutex);
 393
 394         return 0;
 395 }
 396
 397 pure_initcall(net_ns_init);
 398
 399 #ifdef CONFIG_NET_NS
 400 static int __register_pernet_operations(struct list_head *list,
 401                                         struct pernet_operations *ops)
 402 {
 403         struct net *net;
 404         int error;
 405         LIST_HEAD(net_exit_list);
 406
 407         list_add_tail(&ops->list, list);
 408         if (ops->init || (ops->id && ops->size)) {
 409                 for_each_net(net) {
 410                         error = ops_init(ops, net);
 411                         if (error)
 412                                 goto out_undo;
 413                         list_add_tail(&net->exit_list, &net_exit_list);
 414                 }
 415         }
 416         return 0;
 417
 418 out_undo:
 419         /* If I have an error cleanup all namespaces I initialized */
 420         list_del(&ops->list);
 421         ops_exit_list(ops, &net_exit_list);
 422         ops_free_list(ops, &net_exit_list);
 423         return error;
 424 }
 425
 426 static void __unregister_pernet_operations(struct pernet_operations *ops)
 427 {
 428         struct net *net;
 429         LIST_HEAD(net_exit_list);
 430
 431         list_del(&ops->list);
 432         for_each_net(net)
 433                 list_add_tail(&net->exit_list, &net_exit_list);
 434         ops_exit_list(ops, &net_exit_list);
 435         ops_free_list(ops, &net_exit_list);
 436 }
 437
 438 #else
 439
 440 static int __register_pernet_operations(struct list_head *list,
 441                                         struct pernet_operations *ops)
 442 {
 443         int err = 0;
 444         err = ops_init(ops, &init_net);
 445         if (err)
 446                 ops_free(ops, &init_net);
 447         return err;
 448
 449 }
 450
 451 static void __unregister_pernet_operations(struct pernet_operations *ops)
 452 {
 453         LIST_HEAD(net_exit_list);
 454         list_add(&init_net.exit_list, &net_exit_list);
 455         ops_exit_list(ops, &net_exit_list);
 456         ops_free_list(ops, &net_exit_list);
 457 }
 458
 459 #endif /* CONFIG_NET_NS */
 460
 461 static DEFINE_IDA(net_generic_ids);
 462
 463 static int register_pernet_operations(struct list_head *list,
 464                                       struct pernet_operations *ops)
 465 {
 466         int error;
 467
 468         if (ops->id) {
 469 again:
 470                 error = ida_get_new_above(&net_generic_ids, 1, ops->id);
 471                 if (error < 0) {
 472                         if (error == -EAGAIN) {
 473                                 ida_pre_get(&net_generic_ids, GFP_KERNEL);
 474                                 goto again;
 475                         }
 476                         return error;
 477                 }
 478         }
 479         error = __register_pernet_operations(list, ops);
 480         if (error) {
 481                 rcu_barrier();
 482                 if (ops->id)
 483                         ida_remove(&net_generic_ids, *ops->id);
 484         }
 485
 486         return error;
 487 }
 488
 489 static void unregister_pernet_operations(struct pernet_operations *ops)
 490 {
 491
 492         __unregister_pernet_operations(ops);
 493         rcu_barrier();
 494         if (ops->id)
 495                 ida_remove(&net_generic_ids, *ops->id);
 496 }
 497
 498 /**
 499  *      register_pernet_subsys - register a network namespace subsystem
 500  *      @ops:  pernet operations structure for the subsystem
 501  *
 502  *      Register a subsystem which has init and exit functions
 503  *      that are called when network namespaces are created and
 504  *      destroyed respectively.
 505  *
 506  *      When registered all network namespace init functions are
 507  *      called for every existing network namespace.  Allowing kernel
 508  *      modules to have a race free view of the set of network namespaces.
 509  *
 510  *      When a new network namespace is created all of the init
 511  *      methods are called in the order in which they were registered.
 512  *
 513  *      When a network namespace is destroyed all of the exit methods
 514  *      are called in the reverse of the order with which they were
 515  *      registered.
 516  */
 517 int register_pernet_subsys(struct pernet_operations *ops)
 518 {
 519         int error;
 520         mutex_lock(&net_mutex);
 521         error =  register_pernet_operations(first_device, ops);
 522         mutex_unlock(&net_mutex);
 523         return error;
 524 }
 525 EXPORT_SYMBOL_GPL(register_pernet_subsys);
 526
 527 /**
 528  *      unregister_pernet_subsys - unregister a network namespace subsystem
 529  *      @ops: pernet operations structure to manipulate
 530  *
 531  *      Remove the pernet operations structure from the list to be
 532  *      used when network namespaces are created or destroyed.  In
 533  *      addition run the exit method for all existing network
 534  *      namespaces.
 535  */
 536 void unregister_pernet_subsys(struct pernet_operations *ops)
 537 {
 538         mutex_lock(&net_mutex);
 539         unregister_pernet_operations(ops);
 540         mutex_unlock(&net_mutex);
 541 }
 542 EXPORT_SYMBOL_GPL(unregister_pernet_subsys);
 543
 544 /**
 545  *      register_pernet_device - register a network namespace device
 546  *      @ops:  pernet operations structure for the subsystem
 547  *
 548  *      Register a device which has init and exit functions
 549  *      that are called when network namespaces are created and
 550  *      destroyed respectively.
 551  *
 552  *      When registered all network namespace init functions are
 553  *      called for every existing network namespace.  Allowing kernel
 554  *      modules to have a race free view of the set of network namespaces.
 555  *
 556  *      When a new network namespace is created all of the init
 557  *      methods are called in the order in which they were registered.
 558  *
 559  *      When a network namespace is destroyed all of the exit methods
 560  *      are called in the reverse of the order with which they were
 561  *      registered.
 562  */
 563 int register_pernet_device(struct pernet_operations *ops)
 564 {
 565         int error;
 566         mutex_lock(&net_mutex);
 567         error = register_pernet_operations(&pernet_list, ops);
 568         if (!error && (first_device == &pernet_list))
 569                 first_device = &ops->list;
 570         mutex_unlock(&net_mutex);
 571         return error;
 572 }
 573 EXPORT_SYMBOL_GPL(register_pernet_device);
 574
 575 /**
 576  *      unregister_pernet_device - unregister a network namespace netdevice
 577  *      @ops: pernet operations structure to manipulate
 578  *
 579  *      Remove the pernet operations structure from the list to be
 580  *      used when network namespaces are created or destroyed.  In
 581  *      addition run the exit method for all existing network
 582  *      namespaces.
 583  */
 584 void unregister_pernet_device(struct pernet_operations *ops)
 585 {
 586         mutex_lock(&net_mutex);
 587         if (&ops->list == first_device)
 588                 first_device = first_device->next;
 589         unregister_pernet_operations(ops);
 590         mutex_unlock(&net_mutex);
 591 }
 592 EXPORT_SYMBOL_GPL(unregister_pernet_device);
 593
 594 #ifdef CONFIG_NET_NS
 595 static void *netns_get(struct task_struct *task)
 596 {
 597         struct net *net = NULL;
 598         struct nsproxy *nsproxy;
 599
 600         rcu_read_lock();
 601         nsproxy = task_nsproxy(task);
 602         if (nsproxy)
 603                 net = get_net(nsproxy->net_ns);
 604         rcu_read_unlock();
 605
 606         return net;
 607 }
 608
 609 static void netns_put(void *ns)
 610 {
 611         put_net(ns);
 612 }
 613
 614 static int netns_install(struct nsproxy *nsproxy, void *ns)
 615 {
 616         put_net(nsproxy->net_ns);
 617         nsproxy->net_ns = get_net(ns);
 618         return 0;
 619 }
 620
 621 const struct proc_ns_operations netns_operations = {
 622         .name           = "net",
 623         .type           = CLONE_NEWNET,
 624         .get            = netns_get,
 625         .put            = netns_put,
 626         .install        = netns_install,
 627 };
 628 #endif