net/core/net_namespace.c

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
net_alloc_generic
net_assign_generic
ops_init
ops_free
ops_pre_exit_list
ops_exit_list
ops_free_list
alloc_netid
net_eq_idr
__peernet2id_alloc
__peernet2id
peernet2id_alloc
peernet2id
peernet_has_id
get_net_ns_by_id
setup_net
net_defaults_init_net
net_defaults_init
inc_net_namespaces
dec_net_namespaces
net_alloc
net_free
net_drop_ns
copy_net_ns
net_ns_get_ownership
unhash_nsid
cleanup_net
net_ns_barrier
__put_net
get_net_ns_by_fd
get_net_ns_by_fd
get_net_ns_by_pid
net_ns_net_init
net_ns_net_exit
rtnl_net_newid
rtnl_net_get_size
rtnl_net_fill
rtnl_net_valid_getid_req
rtnl_net_getid
rtnl_net_dumpid_one
rtnl_valid_dump_net_req
rtnl_net_dumpid
rtnl_net_notifyid
net_ns_init
__register_pernet_operations
__unregister_pernet_operations
__register_pernet_operations
__unregister_pernet_operations
register_pernet_operations
unregister_pernet_operations
register_pernet_subsys
unregister_pernet_subsys
register_pernet_device
unregister_pernet_device
netns_get
to_net_ns
netns_put
netns_install
netns_owner
   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   3 
   4 #include <linux/workqueue.h>
   5 #include <linux/rtnetlink.h>
   6 #include <linux/cache.h>
   7 #include <linux/slab.h>
   8 #include <linux/list.h>
   9 #include <linux/delay.h>
  10 #include <linux/sched.h>
  11 #include <linux/idr.h>
  12 #include <linux/rculist.h>
  13 #include <linux/nsproxy.h>
  14 #include <linux/fs.h>
  15 #include <linux/proc_ns.h>
  16 #include <linux/file.h>
  17 #include <linux/export.h>
  18 #include <linux/user_namespace.h>
  19 #include <linux/net_namespace.h>
  20 #include <linux/sched/task.h>
  21 #include <linux/uidgid.h>
  22 
  23 #include <net/sock.h>
  24 #include <net/netlink.h>
  25 #include <net/net_namespace.h>
  26 #include <net/netns/generic.h>
  27 
  28 /*
  29  *      Our network namespace constructor/destructor lists
  30  */
  31 
  32 static LIST_HEAD(pernet_list);
  33 static struct list_head *first_device = &pernet_list;
  34 
  35 LIST_HEAD(net_namespace_list);
  36 EXPORT_SYMBOL_GPL(net_namespace_list);
  37 
  38 /* Protects net_namespace_list. Nests iside rtnl_lock() */
  39 DECLARE_RWSEM(net_rwsem);
  40 EXPORT_SYMBOL_GPL(net_rwsem);
  41 
  42 #ifdef CONFIG_KEYS
  43 static struct key_tag init_net_key_domain = { .usage = REFCOUNT_INIT(1) };
  44 #endif
  45 
  46 struct net init_net = {
  47         .count          = REFCOUNT_INIT(1),
  48         .dev_base_head  = LIST_HEAD_INIT(init_net.dev_base_head),
  49 #ifdef CONFIG_KEYS
  50         .key_domain     = &init_net_key_domain,
  51 #endif
  52 };
  53 EXPORT_SYMBOL(init_net);
  54 
  55 static bool init_net_initialized;
  56 /*
  57  * pernet_ops_rwsem: protects: pernet_list, net_generic_ids,
  58  * init_net_initialized and first_device pointer.
  59  * This is internal net namespace object. Please, don't use it
  60  * outside.
  61  */
  62 DECLARE_RWSEM(pernet_ops_rwsem);
  63 EXPORT_SYMBOL_GPL(pernet_ops_rwsem);
  64 
  65 #define MIN_PERNET_OPS_ID       \
  66         ((sizeof(struct net_generic) + sizeof(void *) - 1) / sizeof(void *))
  67 
  68 #define INITIAL_NET_GEN_PTRS    13 /* +1 for len +2 for rcu_head */
  69 
  70 static unsigned int max_gen_ptrs = INITIAL_NET_GEN_PTRS;
  71 
  72 static struct net_generic *net_alloc_generic(void)
  73 {
  74         struct net_generic *ng;
  75         unsigned int generic_size = offsetof(struct net_generic, ptr[max_gen_ptrs]);
  76 
  77         ng = kzalloc(generic_size, GFP_KERNEL);
  78         if (ng)
  79                 ng->s.len = max_gen_ptrs;
  80 
  81         return ng;
  82 }
  83 
  84 static int net_assign_generic(struct net *net, unsigned int id, void *data)
  85 {
  86         struct net_generic *ng, *old_ng;
  87 
  88         BUG_ON(id < MIN_PERNET_OPS_ID);
  89 
  90         old_ng = rcu_dereference_protected(net->gen,
  91                                            lockdep_is_held(&pernet_ops_rwsem));
  92         if (old_ng->s.len > id) {
  93                 old_ng->ptr[id] = data;
  94                 return 0;
  95         }
  96 
  97         ng = net_alloc_generic();
  98         if (ng == NULL)
  99                 return -ENOMEM;
 100 
 101         /*
 102          * Some synchronisation notes:
 103          *
 104          * The net_generic explores the net->gen array inside rcu
 105          * read section. Besides once set the net->gen->ptr[x]
 106          * pointer never changes (see rules in netns/generic.h).
 107          *
 108          * That said, we simply duplicate this array and schedule
 109          * the old copy for kfree after a grace period.
 110          */
 111 
 112         memcpy(&ng->ptr[MIN_PERNET_OPS_ID], &old_ng->ptr[MIN_PERNET_OPS_ID],
 113                (old_ng->s.len - MIN_PERNET_OPS_ID) * sizeof(void *));
 114         ng->ptr[id] = data;
 115 
 116         rcu_assign_pointer(net->gen, ng);
 117         kfree_rcu(old_ng, s.rcu);
 118         return 0;
 119 }
 120 
 121 static int ops_init(const struct pernet_operations *ops, struct net *net)
 122 {
 123         int err = -ENOMEM;
 124         void *data = NULL;
 125 
 126         if (ops->id && ops->size) {
 127                 data = kzalloc(ops->size, GFP_KERNEL);
 128                 if (!data)
 129                         goto out;
 130 
 131                 err = net_assign_generic(net, *ops->id, data);
 132                 if (err)
 133                         goto cleanup;
 134         }
 135         err = 0;
 136         if (ops->init)
 137                 err = ops->init(net);
 138         if (!err)
 139                 return 0;
 140 
 141 cleanup:
 142         kfree(data);
 143 
 144 out:
 145         return err;
 146 }
 147 
 148 static void ops_free(const struct pernet_operations *ops, struct net *net)
 149 {
 150         if (ops->id && ops->size) {
 151                 kfree(net_generic(net, *ops->id));
 152         }
 153 }
 154 
 155 static void ops_pre_exit_list(const struct pernet_operations *ops,
 156                               struct list_head *net_exit_list)
 157 {
 158         struct net *net;
 159 
 160         if (ops->pre_exit) {
 161                 list_for_each_entry(net, net_exit_list, exit_list)
 162                         ops->pre_exit(net);
 163         }
 164 }
 165 
 166 static void ops_exit_list(const struct pernet_operations *ops,
 167                           struct list_head *net_exit_list)
 168 {
 169         struct net *net;
 170         if (ops->exit) {
 171                 list_for_each_entry(net, net_exit_list, exit_list)
 172                         ops->exit(net);
 173         }
 174         if (ops->exit_batch)
 175                 ops->exit_batch(net_exit_list);
 176 }
 177 
 178 static void ops_free_list(const struct pernet_operations *ops,
 179                           struct list_head *net_exit_list)
 180 {
 181         struct net *net;
 182         if (ops->size && ops->id) {
 183                 list_for_each_entry(net, net_exit_list, exit_list)
 184                         ops_free(ops, net);
 185         }
 186 }
 187 
 188 /* should be called with nsid_lock held */
 189 static int alloc_netid(struct net *net, struct net *peer, int reqid)
 190 {
 191         int min = 0, max = 0;
 192 
 193         if (reqid >= 0) {
 194                 min = reqid;
 195                 max = reqid + 1;
 196         }
 197 
 198         return idr_alloc(&net->netns_ids, peer, min, max, GFP_ATOMIC);
 199 }
 200 
 201 /* This function is used by idr_for_each(). If net is equal to peer, the
 202  * function returns the id so that idr_for_each() stops. Because we cannot
 203  * returns the id 0 (idr_for_each() will not stop), we return the magic value
 204  * NET_ID_ZERO (-1) for it.
 205  */
 206 #define NET_ID_ZERO -1
 207 static int net_eq_idr(int id, void *net, void *peer)
 208 {
 209         if (net_eq(net, peer))
 210                 return id ? : NET_ID_ZERO;
 211         return 0;
 212 }
 213 
 214 /* Should be called with nsid_lock held. If a new id is assigned, the bool alloc
 215  * is set to true, thus the caller knows that the new id must be notified via
 216  * rtnl.
 217  */
 218 static int __peernet2id_alloc(struct net *net, struct net *peer, bool *alloc)
 219 {
 220         int id = idr_for_each(&net->netns_ids, net_eq_idr, peer);
 221         bool alloc_it = *alloc;
 222 
 223         *alloc = false;
 224 
 225         /* Magic value for id 0. */
 226         if (id == NET_ID_ZERO)
 227                 return 0;
 228         if (id > 0)
 229                 return id;
 230 
 231         if (alloc_it) {
 232                 id = alloc_netid(net, peer, -1);
 233                 *alloc = true;
 234                 return id >= 0 ? id : NETNSA_NSID_NOT_ASSIGNED;
 235         }
 236 
 237         return NETNSA_NSID_NOT_ASSIGNED;
 238 }
 239 
 240 /* should be called with nsid_lock held */
 241 static int __peernet2id(struct net *net, struct net *peer)
 242 {
 243         bool no = false;
 244 
 245         return __peernet2id_alloc(net, peer, &no);
 246 }
 247 
 248 static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid,
 249                               struct nlmsghdr *nlh, gfp_t gfp);
 250 /* This function returns the id of a peer netns. If no id is assigned, one will
 251  * be allocated and returned.
 252  */
 253 int peernet2id_alloc(struct net *net, struct net *peer, gfp_t gfp)
 254 {
 255         bool alloc = false, alive = false;
 256         int id;
 257 
 258         if (refcount_read(&net->count) == 0)
 259                 return NETNSA_NSID_NOT_ASSIGNED;
 260         spin_lock_bh(&net->nsid_lock);
 261         /*
 262          * When peer is obtained from RCU lists, we may race with
 263          * its cleanup. Check whether it's alive, and this guarantees
 264          * we never hash a peer back to net->netns_ids, after it has
 265          * just been idr_remove()'d from there in cleanup_net().
 266          */
 267         if (maybe_get_net(peer))
 268                 alive = alloc = true;
 269         id = __peernet2id_alloc(net, peer, &alloc);
 270         spin_unlock_bh(&net->nsid_lock);
 271         if (alloc && id >= 0)
 272                 rtnl_net_notifyid(net, RTM_NEWNSID, id, 0, NULL, gfp);
 273         if (alive)
 274                 put_net(peer);
 275         return id;
 276 }
 277 EXPORT_SYMBOL_GPL(peernet2id_alloc);
 278 
 279 /* This function returns, if assigned, the id of a peer netns. */
 280 int peernet2id(struct net *net, struct net *peer)
 281 {
 282         int id;
 283 
 284         spin_lock_bh(&net->nsid_lock);
 285         id = __peernet2id(net, peer);
 286         spin_unlock_bh(&net->nsid_lock);
 287         return id;
 288 }
 289 EXPORT_SYMBOL(peernet2id);
 290 
 291 /* This function returns true is the peer netns has an id assigned into the
 292  * current netns.
 293  */
 294 bool peernet_has_id(struct net *net, struct net *peer)
 295 {
 296         return peernet2id(net, peer) >= 0;
 297 }
 298 
 299 struct net *get_net_ns_by_id(struct net *net, int id)
 300 {
 301         struct net *peer;
 302 
 303         if (id < 0)
 304                 return NULL;
 305 
 306         rcu_read_lock();
 307         peer = idr_find(&net->netns_ids, id);
 308         if (peer)
 309                 peer = maybe_get_net(peer);
 310         rcu_read_unlock();
 311 
 312         return peer;
 313 }
 314 
 315 /*
 316  * setup_net runs the initializers for the network namespace object.
 317  */
 318 static __net_init int setup_net(struct net *net, struct user_namespace *user_ns)
 319 {
 320         /* Must be called with pernet_ops_rwsem held */
 321         const struct pernet_operations *ops, *saved_ops;
 322         int error = 0;
 323         LIST_HEAD(net_exit_list);
 324 
 325         refcount_set(&net->count, 1);
 326         refcount_set(&net->passive, 1);
 327         get_random_bytes(&net->hash_mix, sizeof(u32));
 328         net->dev_base_seq = 1;
 329         net->user_ns = user_ns;
 330         idr_init(&net->netns_ids);
 331         spin_lock_init(&net->nsid_lock);
 332         mutex_init(&net->ipv4.ra_mutex);
 333 
 334         list_for_each_entry(ops, &pernet_list, list) {
 335                 error = ops_init(ops, net);
 336                 if (error < 0)
 337                         goto out_undo;
 338         }
 339         down_write(&net_rwsem);
 340         list_add_tail_rcu(&net->list, &net_namespace_list);
 341         up_write(&net_rwsem);
 342 out:
 343         return error;
 344 
 345 out_undo:
 346         /* Walk through the list backwards calling the exit functions
 347          * for the pernet modules whose init functions did not fail.
 348          */
 349         list_add(&net->exit_list, &net_exit_list);
 350         saved_ops = ops;
 351         list_for_each_entry_continue_reverse(ops, &pernet_list, list)
 352                 ops_pre_exit_list(ops, &net_exit_list);
 353 
 354         synchronize_rcu();
 355 
 356         ops = saved_ops;
 357         list_for_each_entry_continue_reverse(ops, &pernet_list, list)
 358                 ops_exit_list(ops, &net_exit_list);
 359 
 360         ops = saved_ops;
 361         list_for_each_entry_continue_reverse(ops, &pernet_list, list)
 362                 ops_free_list(ops, &net_exit_list);
 363 
 364         rcu_barrier();
 365         goto out;
 366 }
 367 
 368 static int __net_init net_defaults_init_net(struct net *net)
 369 {
 370         net->core.sysctl_somaxconn = SOMAXCONN;
 371         return 0;
 372 }
 373 
 374 static struct pernet_operations net_defaults_ops = {
 375         .init = net_defaults_init_net,
 376 };
 377 
 378 static __init int net_defaults_init(void)
 379 {
 380         if (register_pernet_subsys(&net_defaults_ops))
 381                 panic("Cannot initialize net default settings");
 382 
 383         return 0;
 384 }
 385 
 386 core_initcall(net_defaults_init);
 387 
 388 #ifdef CONFIG_NET_NS
 389 static struct ucounts *inc_net_namespaces(struct user_namespace *ns)
 390 {
 391         return inc_ucount(ns, current_euid(), UCOUNT_NET_NAMESPACES);
 392 }
 393 
 394 static void dec_net_namespaces(struct ucounts *ucounts)
 395 {
 396         dec_ucount(ucounts, UCOUNT_NET_NAMESPACES);
 397 }
 398 
 399 static struct kmem_cache *net_cachep __ro_after_init;
 400 static struct workqueue_struct *netns_wq;
 401 
 402 static struct net *net_alloc(void)
 403 {
 404         struct net *net = NULL;
 405         struct net_generic *ng;
 406 
 407         ng = net_alloc_generic();
 408         if (!ng)
 409                 goto out;
 410 
 411         net = kmem_cache_zalloc(net_cachep, GFP_KERNEL);
 412         if (!net)
 413                 goto out_free;
 414 
 415 #ifdef CONFIG_KEYS
 416         net->key_domain = kzalloc(sizeof(struct key_tag), GFP_KERNEL);
 417         if (!net->key_domain)
 418                 goto out_free_2;
 419         refcount_set(&net->key_domain->usage, 1);
 420 #endif
 421 
 422         rcu_assign_pointer(net->gen, ng);
 423 out:
 424         return net;
 425 
 426 #ifdef CONFIG_KEYS
 427 out_free_2:
 428         kmem_cache_free(net_cachep, net);
 429         net = NULL;
 430 #endif
 431 out_free:
 432         kfree(ng);
 433         goto out;
 434 }
 435 
 436 static void net_free(struct net *net)
 437 {
 438         kfree(rcu_access_pointer(net->gen));
 439         kmem_cache_free(net_cachep, net);
 440 }
 441 
 442 void net_drop_ns(void *p)
 443 {
 444         struct net *ns = p;
 445         if (ns && refcount_dec_and_test(&ns->passive))
 446                 net_free(ns);
 447 }
 448 
 449 struct net *copy_net_ns(unsigned long flags,
 450                         struct user_namespace *user_ns, struct net *old_net)
 451 {
 452         struct ucounts *ucounts;
 453         struct net *net;
 454         int rv;
 455 
 456         if (!(flags & CLONE_NEWNET))
 457                 return get_net(old_net);
 458 
 459         ucounts = inc_net_namespaces(user_ns);
 460         if (!ucounts)
 461                 return ERR_PTR(-ENOSPC);
 462 
 463         net = net_alloc();
 464         if (!net) {
 465                 rv = -ENOMEM;
 466                 goto dec_ucounts;
 467         }
 468         refcount_set(&net->passive, 1);
 469         net->ucounts = ucounts;
 470         get_user_ns(user_ns);
 471 
 472         rv = down_read_killable(&pernet_ops_rwsem);
 473         if (rv < 0)
 474                 goto put_userns;
 475 
 476         rv = setup_net(net, user_ns);
 477 
 478         up_read(&pernet_ops_rwsem);
 479 
 480         if (rv < 0) {
 481 put_userns:
 482                 key_remove_domain(net->key_domain);
 483                 put_user_ns(user_ns);
 484                 net_drop_ns(net);
 485 dec_ucounts:
 486                 dec_net_namespaces(ucounts);
 487                 return ERR_PTR(rv);
 488         }
 489         return net;
 490 }
 491 
 492 /**
 493  * net_ns_get_ownership - get sysfs ownership data for @net
 494  * @net: network namespace in question (can be NULL)
 495  * @uid: kernel user ID for sysfs objects
 496  * @gid: kernel group ID for sysfs objects
 497  *
 498  * Returns the uid/gid pair of root in the user namespace associated with the
 499  * given network namespace.
 500  */
 501 void net_ns_get_ownership(const struct net *net, kuid_t *uid, kgid_t *gid)
 502 {
 503         if (net) {
 504                 kuid_t ns_root_uid = make_kuid(net->user_ns, 0);
 505                 kgid_t ns_root_gid = make_kgid(net->user_ns, 0);
 506 
 507                 if (uid_valid(ns_root_uid))
 508                         *uid = ns_root_uid;
 509 
 510                 if (gid_valid(ns_root_gid))
 511                         *gid = ns_root_gid;
 512         } else {
 513                 *uid = GLOBAL_ROOT_UID;
 514                 *gid = GLOBAL_ROOT_GID;
 515         }
 516 }
 517 EXPORT_SYMBOL_GPL(net_ns_get_ownership);
 518 
 519 static void unhash_nsid(struct net *net, struct net *last)
 520 {
 521         struct net *tmp;
 522         /* This function is only called from cleanup_net() work,
 523          * and this work is the only process, that may delete
 524          * a net from net_namespace_list. So, when the below
 525          * is executing, the list may only grow. Thus, we do not
 526          * use for_each_net_rcu() or net_rwsem.
 527          */
 528         for_each_net(tmp) {
 529                 int id;
 530 
 531                 spin_lock_bh(&tmp->nsid_lock);
 532                 id = __peernet2id(tmp, net);
 533                 if (id >= 0)
 534                         idr_remove(&tmp->netns_ids, id);
 535                 spin_unlock_bh(&tmp->nsid_lock);
 536                 if (id >= 0)
 537                         rtnl_net_notifyid(tmp, RTM_DELNSID, id, 0, NULL,
 538                                           GFP_KERNEL);
 539                 if (tmp == last)
 540                         break;
 541         }
 542         spin_lock_bh(&net->nsid_lock);
 543         idr_destroy(&net->netns_ids);
 544         spin_unlock_bh(&net->nsid_lock);
 545 }
 546 
 547 static LLIST_HEAD(cleanup_list);
 548 
 549 static void cleanup_net(struct work_struct *work)
 550 {
 551         const struct pernet_operations *ops;
 552         struct net *net, *tmp, *last;
 553         struct llist_node *net_kill_list;
 554         LIST_HEAD(net_exit_list);
 555 
 556         /* Atomically snapshot the list of namespaces to cleanup */
 557         net_kill_list = llist_del_all(&cleanup_list);
 558 
 559         down_read(&pernet_ops_rwsem);
 560 
 561         /* Don't let anyone else find us. */
 562         down_write(&net_rwsem);
 563         llist_for_each_entry(net, net_kill_list, cleanup_list)
 564                 list_del_rcu(&net->list);
 565         /* Cache last net. After we unlock rtnl, no one new net
 566          * added to net_namespace_list can assign nsid pointer
 567          * to a net from net_kill_list (see peernet2id_alloc()).
 568          * So, we skip them in unhash_nsid().
 569          *
 570          * Note, that unhash_nsid() does not delete nsid links
 571          * between net_kill_list's nets, as they've already
 572          * deleted from net_namespace_list. But, this would be
 573          * useless anyway, as netns_ids are destroyed there.
 574          */
 575         last = list_last_entry(&net_namespace_list, struct net, list);
 576         up_write(&net_rwsem);
 577 
 578         llist_for_each_entry(net, net_kill_list, cleanup_list) {
 579                 unhash_nsid(net, last);
 580                 list_add_tail(&net->exit_list, &net_exit_list);
 581         }
 582 
 583         /* Run all of the network namespace pre_exit methods */
 584         list_for_each_entry_reverse(ops, &pernet_list, list)
 585                 ops_pre_exit_list(ops, &net_exit_list);
 586 
 587         /*
 588          * Another CPU might be rcu-iterating the list, wait for it.
 589          * This needs to be before calling the exit() notifiers, so
 590          * the rcu_barrier() below isn't sufficient alone.
 591          * Also the pre_exit() and exit() methods need this barrier.
 592          */
 593         synchronize_rcu();
 594 
 595         /* Run all of the network namespace exit methods */
 596         list_for_each_entry_reverse(ops, &pernet_list, list)
 597                 ops_exit_list(ops, &net_exit_list);
 598 
 599         /* Free the net generic variables */
 600         list_for_each_entry_reverse(ops, &pernet_list, list)
 601                 ops_free_list(ops, &net_exit_list);
 602 
 603         up_read(&pernet_ops_rwsem);
 604 
 605         /* Ensure there are no outstanding rcu callbacks using this
 606          * network namespace.
 607          */
 608         rcu_barrier();
 609 
 610         /* Finally it is safe to free my network namespace structure */
 611         list_for_each_entry_safe(net, tmp, &net_exit_list, exit_list) {
 612                 list_del_init(&net->exit_list);
 613                 dec_net_namespaces(net->ucounts);
 614                 key_remove_domain(net->key_domain);
 615                 put_user_ns(net->user_ns);
 616                 net_drop_ns(net);
 617         }
 618 }
 619 
 620 /**
 621  * net_ns_barrier - wait until concurrent net_cleanup_work is done
 622  *
 623  * cleanup_net runs from work queue and will first remove namespaces
 624  * from the global list, then run net exit functions.
 625  *
 626  * Call this in module exit path to make sure that all netns
 627  * ->exit ops have been invoked before the function is removed.
 628  */
 629 void net_ns_barrier(void)
 630 {
 631         down_write(&pernet_ops_rwsem);
 632         up_write(&pernet_ops_rwsem);
 633 }
 634 EXPORT_SYMBOL(net_ns_barrier);
 635 
 636 static DECLARE_WORK(net_cleanup_work, cleanup_net);
 637 
 638 void __put_net(struct net *net)
 639 {
 640         /* Cleanup the network namespace in process context */
 641         if (llist_add(&net->cleanup_list, &cleanup_list))
 642                 queue_work(netns_wq, &net_cleanup_work);
 643 }
 644 EXPORT_SYMBOL_GPL(__put_net);
 645 
 646 struct net *get_net_ns_by_fd(int fd)
 647 {
 648         struct file *file;
 649         struct ns_common *ns;
 650         struct net *net;
 651 
 652         file = proc_ns_fget(fd);
 653         if (IS_ERR(file))
 654                 return ERR_CAST(file);
 655 
 656         ns = get_proc_ns(file_inode(file));
 657         if (ns->ops == &netns_operations)
 658                 net = get_net(container_of(ns, struct net, ns));
 659         else
 660                 net = ERR_PTR(-EINVAL);
 661 
 662         fput(file);
 663         return net;
 664 }
 665 
 666 #else
 667 struct net *get_net_ns_by_fd(int fd)
 668 {
 669         return ERR_PTR(-EINVAL);
 670 }
 671 #endif
 672 EXPORT_SYMBOL_GPL(get_net_ns_by_fd);
 673 
 674 struct net *get_net_ns_by_pid(pid_t pid)
 675 {
 676         struct task_struct *tsk;
 677         struct net *net;
 678 
 679         /* Lookup the network namespace */
 680         net = ERR_PTR(-ESRCH);
 681         rcu_read_lock();
 682         tsk = find_task_by_vpid(pid);
 683         if (tsk) {
 684                 struct nsproxy *nsproxy;
 685                 task_lock(tsk);
 686                 nsproxy = tsk->nsproxy;
 687                 if (nsproxy)
 688                         net = get_net(nsproxy->net_ns);
 689                 task_unlock(tsk);
 690         }
 691         rcu_read_unlock();
 692         return net;
 693 }
 694 EXPORT_SYMBOL_GPL(get_net_ns_by_pid);
 695 
 696 static __net_init int net_ns_net_init(struct net *net)
 697 {
 698 #ifdef CONFIG_NET_NS
 699         net->ns.ops = &netns_operations;
 700 #endif
 701         return ns_alloc_inum(&net->ns);
 702 }
 703 
 704 static __net_exit void net_ns_net_exit(struct net *net)
 705 {
 706         ns_free_inum(&net->ns);
 707 }
 708 
 709 static struct pernet_operations __net_initdata net_ns_ops = {
 710         .init = net_ns_net_init,
 711         .exit = net_ns_net_exit,
 712 };
 713 
 714 static const struct nla_policy rtnl_net_policy[NETNSA_MAX + 1] = {
 715         [NETNSA_NONE]           = { .type = NLA_UNSPEC },
 716         [NETNSA_NSID]           = { .type = NLA_S32 },
 717         [NETNSA_PID]            = { .type = NLA_U32 },
 718         [NETNSA_FD]             = { .type = NLA_U32 },
 719         [NETNSA_TARGET_NSID]    = { .type = NLA_S32 },
 720 };
 721 
 722 static int rtnl_net_newid(struct sk_buff *skb, struct nlmsghdr *nlh,
 723                           struct netlink_ext_ack *extack)
 724 {
 725         struct net *net = sock_net(skb->sk);
 726         struct nlattr *tb[NETNSA_MAX + 1];
 727         struct nlattr *nla;
 728         struct net *peer;
 729         int nsid, err;
 730 
 731         err = nlmsg_parse_deprecated(nlh, sizeof(struct rtgenmsg), tb,
 732                                      NETNSA_MAX, rtnl_net_policy, extack);
 733         if (err < 0)
 734                 return err;
 735         if (!tb[NETNSA_NSID]) {
 736                 NL_SET_ERR_MSG(extack, "nsid is missing");
 737                 return -EINVAL;
 738         }
 739         nsid = nla_get_s32(tb[NETNSA_NSID]);
 740 
 741         if (tb[NETNSA_PID]) {
 742                 peer = get_net_ns_by_pid(nla_get_u32(tb[NETNSA_PID]));
 743                 nla = tb[NETNSA_PID];
 744         } else if (tb[NETNSA_FD]) {
 745                 peer = get_net_ns_by_fd(nla_get_u32(tb[NETNSA_FD]));
 746                 nla = tb[NETNSA_FD];
 747         } else {
 748                 NL_SET_ERR_MSG(extack, "Peer netns reference is missing");
 749                 return -EINVAL;
 750         }
 751         if (IS_ERR(peer)) {
 752                 NL_SET_BAD_ATTR(extack, nla);
 753                 NL_SET_ERR_MSG(extack, "Peer netns reference is invalid");
 754                 return PTR_ERR(peer);
 755         }
 756 
 757         spin_lock_bh(&net->nsid_lock);
 758         if (__peernet2id(net, peer) >= 0) {
 759                 spin_unlock_bh(&net->nsid_lock);
 760                 err = -EEXIST;
 761                 NL_SET_BAD_ATTR(extack, nla);
 762                 NL_SET_ERR_MSG(extack,
 763                                "Peer netns already has a nsid assigned");
 764                 goto out;
 765         }
 766 
 767         err = alloc_netid(net, peer, nsid);
 768         spin_unlock_bh(&net->nsid_lock);
 769         if (err >= 0) {
 770                 rtnl_net_notifyid(net, RTM_NEWNSID, err, NETLINK_CB(skb).portid,
 771                                   nlh, GFP_KERNEL);
 772                 err = 0;
 773         } else if (err == -ENOSPC && nsid >= 0) {
 774                 err = -EEXIST;
 775                 NL_SET_BAD_ATTR(extack, tb[NETNSA_NSID]);
 776                 NL_SET_ERR_MSG(extack, "The specified nsid is already used");
 777         }
 778 out:
 779         put_net(peer);
 780         return err;
 781 }
 782 
 783 static int rtnl_net_get_size(void)
 784 {
 785         return NLMSG_ALIGN(sizeof(struct rtgenmsg))
 786                + nla_total_size(sizeof(s32)) /* NETNSA_NSID */
 787                + nla_total_size(sizeof(s32)) /* NETNSA_CURRENT_NSID */
 788                ;
 789 }
 790 
 791 struct net_fill_args {
 792         u32 portid;
 793         u32 seq;
 794         int flags;
 795         int cmd;
 796         int nsid;
 797         bool add_ref;
 798         int ref_nsid;
 799 };
 800 
 801 static int rtnl_net_fill(struct sk_buff *skb, struct net_fill_args *args)
 802 {
 803         struct nlmsghdr *nlh;
 804         struct rtgenmsg *rth;
 805 
 806         nlh = nlmsg_put(skb, args->portid, args->seq, args->cmd, sizeof(*rth),
 807                         args->flags);
 808         if (!nlh)
 809                 return -EMSGSIZE;
 810 
 811         rth = nlmsg_data(nlh);
 812         rth->rtgen_family = AF_UNSPEC;
 813 
 814         if (nla_put_s32(skb, NETNSA_NSID, args->nsid))
 815                 goto nla_put_failure;
 816 
 817         if (args->add_ref &&
 818             nla_put_s32(skb, NETNSA_CURRENT_NSID, args->ref_nsid))
 819                 goto nla_put_failure;
 820 
 821         nlmsg_end(skb, nlh);
 822         return 0;
 823 
 824 nla_put_failure:
 825         nlmsg_cancel(skb, nlh);
 826         return -EMSGSIZE;
 827 }
 828 
 829 static int rtnl_net_valid_getid_req(struct sk_buff *skb,
 830                                     const struct nlmsghdr *nlh,
 831                                     struct nlattr **tb,
 832                                     struct netlink_ext_ack *extack)
 833 {
 834         int i, err;
 835 
 836         if (!netlink_strict_get_check(skb))
 837                 return nlmsg_parse_deprecated(nlh, sizeof(struct rtgenmsg),
 838                                               tb, NETNSA_MAX, rtnl_net_policy,
 839                                               extack);
 840 
 841         err = nlmsg_parse_deprecated_strict(nlh, sizeof(struct rtgenmsg), tb,
 842                                             NETNSA_MAX, rtnl_net_policy,
 843                                             extack);
 844         if (err)
 845                 return err;
 846 
 847         for (i = 0; i <= NETNSA_MAX; i++) {
 848                 if (!tb[i])
 849                         continue;
 850 
 851                 switch (i) {
 852                 case NETNSA_PID:
 853                 case NETNSA_FD:
 854                 case NETNSA_NSID:
 855                 case NETNSA_TARGET_NSID:
 856                         break;
 857                 default:
 858                         NL_SET_ERR_MSG(extack, "Unsupported attribute in peer netns getid request");
 859                         return -EINVAL;
 860                 }
 861         }
 862 
 863         return 0;
 864 }
 865 
 866 static int rtnl_net_getid(struct sk_buff *skb, struct nlmsghdr *nlh,
 867                           struct netlink_ext_ack *extack)
 868 {
 869         struct net *net = sock_net(skb->sk);
 870         struct nlattr *tb[NETNSA_MAX + 1];
 871         struct net_fill_args fillargs = {
 872                 .portid = NETLINK_CB(skb).portid,
 873                 .seq = nlh->nlmsg_seq,
 874                 .cmd = RTM_NEWNSID,
 875         };
 876         struct net *peer, *target = net;
 877         struct nlattr *nla;
 878         struct sk_buff *msg;
 879         int err;
 880 
 881         err = rtnl_net_valid_getid_req(skb, nlh, tb, extack);
 882         if (err < 0)
 883                 return err;
 884         if (tb[NETNSA_PID]) {
 885                 peer = get_net_ns_by_pid(nla_get_u32(tb[NETNSA_PID]));
 886                 nla = tb[NETNSA_PID];
 887         } else if (tb[NETNSA_FD]) {
 888                 peer = get_net_ns_by_fd(nla_get_u32(tb[NETNSA_FD]));
 889                 nla = tb[NETNSA_FD];
 890         } else if (tb[NETNSA_NSID]) {
 891                 peer = get_net_ns_by_id(net, nla_get_s32(tb[NETNSA_NSID]));
 892                 if (!peer)
 893                         peer = ERR_PTR(-ENOENT);
 894                 nla = tb[NETNSA_NSID];
 895         } else {
 896                 NL_SET_ERR_MSG(extack, "Peer netns reference is missing");
 897                 return -EINVAL;
 898         }
 899 
 900         if (IS_ERR(peer)) {
 901                 NL_SET_BAD_ATTR(extack, nla);
 902                 NL_SET_ERR_MSG(extack, "Peer netns reference is invalid");
 903                 return PTR_ERR(peer);
 904         }
 905 
 906         if (tb[NETNSA_TARGET_NSID]) {
 907                 int id = nla_get_s32(tb[NETNSA_TARGET_NSID]);
 908 
 909                 target = rtnl_get_net_ns_capable(NETLINK_CB(skb).sk, id);
 910                 if (IS_ERR(target)) {
 911                         NL_SET_BAD_ATTR(extack, tb[NETNSA_TARGET_NSID]);
 912                         NL_SET_ERR_MSG(extack,
 913                                        "Target netns reference is invalid");
 914                         err = PTR_ERR(target);
 915                         goto out;
 916                 }
 917                 fillargs.add_ref = true;
 918                 fillargs.ref_nsid = peernet2id(net, peer);
 919         }
 920 
 921         msg = nlmsg_new(rtnl_net_get_size(), GFP_KERNEL);
 922         if (!msg) {
 923                 err = -ENOMEM;
 924                 goto out;
 925         }
 926 
 927         fillargs.nsid = peernet2id(target, peer);
 928         err = rtnl_net_fill(msg, &fillargs);
 929         if (err < 0)
 930                 goto err_out;
 931 
 932         err = rtnl_unicast(msg, net, NETLINK_CB(skb).portid);
 933         goto out;
 934 
 935 err_out:
 936         nlmsg_free(msg);
 937 out:
 938         if (fillargs.add_ref)
 939                 put_net(target);
 940         put_net(peer);
 941         return err;
 942 }
 943 
 944 struct rtnl_net_dump_cb {
 945         struct net *tgt_net;
 946         struct net *ref_net;
 947         struct sk_buff *skb;
 948         struct net_fill_args fillargs;
 949         int idx;
 950         int s_idx;
 951 };
 952 
 953 static int rtnl_net_dumpid_one(int id, void *peer, void *data)
 954 {
 955         struct rtnl_net_dump_cb *net_cb = (struct rtnl_net_dump_cb *)data;
 956         int ret;
 957 
 958         if (net_cb->idx < net_cb->s_idx)
 959                 goto cont;
 960 
 961         net_cb->fillargs.nsid = id;
 962         if (net_cb->fillargs.add_ref)
 963                 net_cb->fillargs.ref_nsid = __peernet2id(net_cb->ref_net, peer);
 964         ret = rtnl_net_fill(net_cb->skb, &net_cb->fillargs);
 965         if (ret < 0)
 966                 return ret;
 967 
 968 cont:
 969         net_cb->idx++;
 970         return 0;
 971 }
 972 
 973 static int rtnl_valid_dump_net_req(const struct nlmsghdr *nlh, struct sock *sk,
 974                                    struct rtnl_net_dump_cb *net_cb,
 975                                    struct netlink_callback *cb)
 976 {
 977         struct netlink_ext_ack *extack = cb->extack;
 978         struct nlattr *tb[NETNSA_MAX + 1];
 979         int err, i;
 980 
 981         err = nlmsg_parse_deprecated_strict(nlh, sizeof(struct rtgenmsg), tb,
 982                                             NETNSA_MAX, rtnl_net_policy,
 983                                             extack);
 984         if (err < 0)
 985                 return err;
 986 
 987         for (i = 0; i <= NETNSA_MAX; i++) {
 988                 if (!tb[i])
 989                         continue;
 990 
 991                 if (i == NETNSA_TARGET_NSID) {
 992                         struct net *net;
 993 
 994                         net = rtnl_get_net_ns_capable(sk, nla_get_s32(tb[i]));
 995                         if (IS_ERR(net)) {
 996                                 NL_SET_BAD_ATTR(extack, tb[i]);
 997                                 NL_SET_ERR_MSG(extack,
 998                                                "Invalid target network namespace id");
 999                                 return PTR_ERR(net);
1000                         }
1001                         net_cb->fillargs.add_ref = true;
1002                         net_cb->ref_net = net_cb->tgt_net;
1003                         net_cb->tgt_net = net;
1004                 } else {
1005                         NL_SET_BAD_ATTR(extack, tb[i]);
1006                         NL_SET_ERR_MSG(extack,
1007                                        "Unsupported attribute in dump request");
1008                         return -EINVAL;
1009                 }
1010         }
1011 
1012         return 0;
1013 }
1014 
1015 static int rtnl_net_dumpid(struct sk_buff *skb, struct netlink_callback *cb)
1016 {
1017         struct rtnl_net_dump_cb net_cb = {
1018                 .tgt_net = sock_net(skb->sk),
1019                 .skb = skb,
1020                 .fillargs = {
1021                         .portid = NETLINK_CB(cb->skb).portid,
1022                         .seq = cb->nlh->nlmsg_seq,
1023                         .flags = NLM_F_MULTI,
1024                         .cmd = RTM_NEWNSID,
1025                 },
1026                 .idx = 0,
1027                 .s_idx = cb->args[0],
1028         };
1029         int err = 0;
1030 
1031         if (cb->strict_check) {
1032                 err = rtnl_valid_dump_net_req(cb->nlh, skb->sk, &net_cb, cb);
1033                 if (err < 0)
1034                         goto end;
1035         }
1036 
1037         spin_lock_bh(&net_cb.tgt_net->nsid_lock);
1038         if (net_cb.fillargs.add_ref &&
1039             !net_eq(net_cb.ref_net, net_cb.tgt_net) &&
1040             !spin_trylock_bh(&net_cb.ref_net->nsid_lock)) {
1041                 spin_unlock_bh(&net_cb.tgt_net->nsid_lock);
1042                 err = -EAGAIN;
1043                 goto end;
1044         }
1045         idr_for_each(&net_cb.tgt_net->netns_ids, rtnl_net_dumpid_one, &net_cb);
1046         if (net_cb.fillargs.add_ref &&
1047             !net_eq(net_cb.ref_net, net_cb.tgt_net))
1048                 spin_unlock_bh(&net_cb.ref_net->nsid_lock);
1049         spin_unlock_bh(&net_cb.tgt_net->nsid_lock);
1050 
1051         cb->args[0] = net_cb.idx;
1052 end:
1053         if (net_cb.fillargs.add_ref)
1054                 put_net(net_cb.tgt_net);
1055         return err < 0 ? err : skb->len;
1056 }
1057 
1058 static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid,
1059                               struct nlmsghdr *nlh, gfp_t gfp)
1060 {
1061         struct net_fill_args fillargs = {
1062                 .portid = portid,
1063                 .seq = nlh ? nlh->nlmsg_seq : 0,
1064                 .cmd = cmd,
1065                 .nsid = id,
1066         };
1067         struct sk_buff *msg;
1068         int err = -ENOMEM;
1069 
1070         msg = nlmsg_new(rtnl_net_get_size(), gfp);
1071         if (!msg)
1072                 goto out;
1073 
1074         err = rtnl_net_fill(msg, &fillargs);
1075         if (err < 0)
1076                 goto err_out;
1077 
1078         rtnl_notify(msg, net, portid, RTNLGRP_NSID, nlh, gfp);
1079         return;
1080 
1081 err_out:
1082         nlmsg_free(msg);
1083 out:
1084         rtnl_set_sk_err(net, RTNLGRP_NSID, err);
1085 }
1086 
1087 static int __init net_ns_init(void)
1088 {
1089         struct net_generic *ng;
1090 
1091 #ifdef CONFIG_NET_NS
1092         net_cachep = kmem_cache_create("net_namespace", sizeof(struct net),
1093                                         SMP_CACHE_BYTES,
1094                                         SLAB_PANIC|SLAB_ACCOUNT, NULL);
1095 
1096         /* Create workqueue for cleanup */
1097         netns_wq = create_singlethread_workqueue("netns");
1098         if (!netns_wq)
1099                 panic("Could not create netns workq");
1100 #endif
1101 
1102         ng = net_alloc_generic();
1103         if (!ng)
1104                 panic("Could not allocate generic netns");
1105 
1106         rcu_assign_pointer(init_net.gen, ng);
1107 
1108         down_write(&pernet_ops_rwsem);
1109         if (setup_net(&init_net, &init_user_ns))
1110                 panic("Could not setup the initial network namespace");
1111 
1112         init_net_initialized = true;
1113         up_write(&pernet_ops_rwsem);
1114 
1115         if (register_pernet_subsys(&net_ns_ops))
1116                 panic("Could not register network namespace subsystems");
1117 
1118         rtnl_register(PF_UNSPEC, RTM_NEWNSID, rtnl_net_newid, NULL,
1119                       RTNL_FLAG_DOIT_UNLOCKED);
1120         rtnl_register(PF_UNSPEC, RTM_GETNSID, rtnl_net_getid, rtnl_net_dumpid,
1121                       RTNL_FLAG_DOIT_UNLOCKED);
1122 
1123         return 0;
1124 }
1125 
1126 pure_initcall(net_ns_init);
1127 
1128 #ifdef CONFIG_NET_NS
1129 static int __register_pernet_operations(struct list_head *list,
1130                                         struct pernet_operations *ops)
1131 {
1132         struct net *net;
1133         int error;
1134         LIST_HEAD(net_exit_list);
1135 
1136         list_add_tail(&ops->list, list);
1137         if (ops->init || (ops->id && ops->size)) {
1138                 /* We held write locked pernet_ops_rwsem, and parallel
1139                  * setup_net() and cleanup_net() are not possible.
1140                  */
1141                 for_each_net(net) {
1142                         error = ops_init(ops, net);
1143                         if (error)
1144                                 goto out_undo;
1145                         list_add_tail(&net->exit_list, &net_exit_list);
1146                 }
1147         }
1148         return 0;
1149 
1150 out_undo:
1151         /* If I have an error cleanup all namespaces I initialized */
1152         list_del(&ops->list);
1153         ops_pre_exit_list(ops, &net_exit_list);
1154         synchronize_rcu();
1155         ops_exit_list(ops, &net_exit_list);
1156         ops_free_list(ops, &net_exit_list);
1157         return error;
1158 }
1159 
1160 static void __unregister_pernet_operations(struct pernet_operations *ops)
1161 {
1162         struct net *net;
1163         LIST_HEAD(net_exit_list);
1164 
1165         list_del(&ops->list);
1166         /* See comment in __register_pernet_operations() */
1167         for_each_net(net)
1168                 list_add_tail(&net->exit_list, &net_exit_list);
1169         ops_pre_exit_list(ops, &net_exit_list);
1170         synchronize_rcu();
1171         ops_exit_list(ops, &net_exit_list);
1172         ops_free_list(ops, &net_exit_list);
1173 }
1174 
1175 #else
1176 
1177 static int __register_pernet_operations(struct list_head *list,
1178                                         struct pernet_operations *ops)
1179 {
1180         if (!init_net_initialized) {
1181                 list_add_tail(&ops->list, list);
1182                 return 0;
1183         }
1184 
1185         return ops_init(ops, &init_net);
1186 }
1187 
1188 static void __unregister_pernet_operations(struct pernet_operations *ops)
1189 {
1190         if (!init_net_initialized) {
1191                 list_del(&ops->list);
1192         } else {
1193                 LIST_HEAD(net_exit_list);
1194                 list_add(&init_net.exit_list, &net_exit_list);
1195                 ops_pre_exit_list(ops, &net_exit_list);
1196                 synchronize_rcu();
1197                 ops_exit_list(ops, &net_exit_list);
1198                 ops_free_list(ops, &net_exit_list);
1199         }
1200 }
1201 
1202 #endif /* CONFIG_NET_NS */
1203 
1204 static DEFINE_IDA(net_generic_ids);
1205 
1206 static int register_pernet_operations(struct list_head *list,
1207                                       struct pernet_operations *ops)
1208 {
1209         int error;
1210 
1211         if (ops->id) {
1212                 error = ida_alloc_min(&net_generic_ids, MIN_PERNET_OPS_ID,
1213                                 GFP_KERNEL);
1214                 if (error < 0)
1215                         return error;
1216                 *ops->id = error;
1217                 max_gen_ptrs = max(max_gen_ptrs, *ops->id + 1);
1218         }
1219         error = __register_pernet_operations(list, ops);
1220         if (error) {
1221                 rcu_barrier();
1222                 if (ops->id)
1223                         ida_free(&net_generic_ids, *ops->id);
1224         }
1225 
1226         return error;
1227 }
1228 
1229 static void unregister_pernet_operations(struct pernet_operations *ops)
1230 {
1231         __unregister_pernet_operations(ops);
1232         rcu_barrier();
1233         if (ops->id)
1234                 ida_free(&net_generic_ids, *ops->id);
1235 }
1236 
1237 /**
1238  *      register_pernet_subsys - register a network namespace subsystem
1239  *      @ops:  pernet operations structure for the subsystem
1240  *
1241  *      Register a subsystem which has init and exit functions
1242  *      that are called when network namespaces are created and
1243  *      destroyed respectively.
1244  *
1245  *      When registered all network namespace init functions are
1246  *      called for every existing network namespace.  Allowing kernel
1247  *      modules to have a race free view of the set of network namespaces.
1248  *
1249  *      When a new network namespace is created all of the init
1250  *      methods are called in the order in which they were registered.
1251  *
1252  *      When a network namespace is destroyed all of the exit methods
1253  *      are called in the reverse of the order with which they were
1254  *      registered.
1255  */
1256 int register_pernet_subsys(struct pernet_operations *ops)
1257 {
1258         int error;
1259         down_write(&pernet_ops_rwsem);
1260         error =  register_pernet_operations(first_device, ops);
1261         up_write(&pernet_ops_rwsem);
1262         return error;
1263 }
1264 EXPORT_SYMBOL_GPL(register_pernet_subsys);
1265 
1266 /**
1267  *      unregister_pernet_subsys - unregister a network namespace subsystem
1268  *      @ops: pernet operations structure to manipulate
1269  *
1270  *      Remove the pernet operations structure from the list to be
1271  *      used when network namespaces are created or destroyed.  In
1272  *      addition run the exit method for all existing network
1273  *      namespaces.
1274  */
1275 void unregister_pernet_subsys(struct pernet_operations *ops)
1276 {
1277         down_write(&pernet_ops_rwsem);
1278         unregister_pernet_operations(ops);
1279         up_write(&pernet_ops_rwsem);
1280 }
1281 EXPORT_SYMBOL_GPL(unregister_pernet_subsys);
1282 
1283 /**
1284  *      register_pernet_device - register a network namespace device
1285  *      @ops:  pernet operations structure for the subsystem
1286  *
1287  *      Register a device which has init and exit functions
1288  *      that are called when network namespaces are created and
1289  *      destroyed respectively.
1290  *
1291  *      When registered all network namespace init functions are
1292  *      called for every existing network namespace.  Allowing kernel
1293  *      modules to have a race free view of the set of network namespaces.
1294  *
1295  *      When a new network namespace is created all of the init
1296  *      methods are called in the order in which they were registered.
1297  *
1298  *      When a network namespace is destroyed all of the exit methods
1299  *      are called in the reverse of the order with which they were
1300  *      registered.
1301  */
1302 int register_pernet_device(struct pernet_operations *ops)
1303 {
1304         int error;
1305         down_write(&pernet_ops_rwsem);
1306         error = register_pernet_operations(&pernet_list, ops);
1307         if (!error && (first_device == &pernet_list))
1308                 first_device = &ops->list;
1309         up_write(&pernet_ops_rwsem);
1310         return error;
1311 }
1312 EXPORT_SYMBOL_GPL(register_pernet_device);
1313 
1314 /**
1315  *      unregister_pernet_device - unregister a network namespace netdevice
1316  *      @ops: pernet operations structure to manipulate
1317  *
1318  *      Remove the pernet operations structure from the list to be
1319  *      used when network namespaces are created or destroyed.  In
1320  *      addition run the exit method for all existing network
1321  *      namespaces.
1322  */
1323 void unregister_pernet_device(struct pernet_operations *ops)
1324 {
1325         down_write(&pernet_ops_rwsem);
1326         if (&ops->list == first_device)
1327                 first_device = first_device->next;
1328         unregister_pernet_operations(ops);
1329         up_write(&pernet_ops_rwsem);
1330 }
1331 EXPORT_SYMBOL_GPL(unregister_pernet_device);
1332 
1333 #ifdef CONFIG_NET_NS
1334 static struct ns_common *netns_get(struct task_struct *task)
1335 {
1336         struct net *net = NULL;
1337         struct nsproxy *nsproxy;
1338 
1339         task_lock(task);
1340         nsproxy = task->nsproxy;
1341         if (nsproxy)
1342                 net = get_net(nsproxy->net_ns);
1343         task_unlock(task);
1344 
1345         return net ? &net->ns : NULL;
1346 }
1347 
1348 static inline struct net *to_net_ns(struct ns_common *ns)
1349 {
1350         return container_of(ns, struct net, ns);
1351 }
1352 
1353 static void netns_put(struct ns_common *ns)
1354 {
1355         put_net(to_net_ns(ns));
1356 }
1357 
1358 static int netns_install(struct nsproxy *nsproxy, struct ns_common *ns)
1359 {
1360         struct net *net = to_net_ns(ns);
1361 
1362         if (!ns_capable(net->user_ns, CAP_SYS_ADMIN) ||
1363             !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
1364                 return -EPERM;
1365 
1366         put_net(nsproxy->net_ns);
1367         nsproxy->net_ns = get_net(net);
1368         return 0;
1369 }
1370 
1371 static struct user_namespace *netns_owner(struct ns_common *ns)
1372 {
1373         return to_net_ns(ns)->user_ns;
1374 }
1375 
1376 const struct proc_ns_operations netns_operations = {
1377         .name           = "net",
1378         .type           = CLONE_NEWNET,
1379         .get            = netns_get,
1380         .put            = netns_put,
1381         .install        = netns_install,
1382         .owner          = netns_owner,
1383 };
1384 #endif
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root/net/core/net_namespace.c

DEFINITIONS
