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#include <linux/cookie.h>
  23#include <linux/proc_fs.h>
  24
  25#include <net/sock.h>
  26#include <net/netlink.h>
  27#include <net/net_namespace.h>
  28#include <net/netns/generic.h>
  29
  30/*
  31 *	Our network namespace constructor/destructor lists
  32 */
  33
  34static LIST_HEAD(pernet_list);
  35static struct list_head *first_device = &pernet_list;
  36
  37LIST_HEAD(net_namespace_list);
  38EXPORT_SYMBOL_GPL(net_namespace_list);
  39
  40/* Protects net_namespace_list. Nests iside rtnl_lock() */
  41DECLARE_RWSEM(net_rwsem);
  42EXPORT_SYMBOL_GPL(net_rwsem);
  43
  44#ifdef CONFIG_KEYS
  45static struct key_tag init_net_key_domain = { .usage = REFCOUNT_INIT(1) };
  46#endif
  47
  48struct net init_net;
  49EXPORT_SYMBOL(init_net);
  50
  51static bool init_net_initialized;
  52/*
  53 * pernet_ops_rwsem: protects: pernet_list, net_generic_ids,
  54 * init_net_initialized and first_device pointer.
  55 * This is internal net namespace object. Please, don't use it
  56 * outside.
  57 */
  58DECLARE_RWSEM(pernet_ops_rwsem);
  59EXPORT_SYMBOL_GPL(pernet_ops_rwsem);
  60
  61#define MIN_PERNET_OPS_ID	\
  62	((sizeof(struct net_generic) + sizeof(void *) - 1) / sizeof(void *))
  63
  64#define INITIAL_NET_GEN_PTRS	13 /* +1 for len +2 for rcu_head */
  65
  66static unsigned int max_gen_ptrs = INITIAL_NET_GEN_PTRS;
  67
  68DEFINE_COOKIE(net_cookie);
  69
  70static struct net_generic *net_alloc_generic(void)
  71{
  72	unsigned int gen_ptrs = READ_ONCE(max_gen_ptrs);
  73	unsigned int generic_size;
  74	struct net_generic *ng;
  75
  76	generic_size = offsetof(struct net_generic, ptr[gen_ptrs]);
  77
  78	ng = kzalloc(generic_size, GFP_KERNEL);
  79	if (ng)
  80		ng->s.len = gen_ptrs;
  81
  82	return ng;
  83}
  84
  85static int net_assign_generic(struct net *net, unsigned int id, void *data)
  86{
  87	struct net_generic *ng, *old_ng;
  88
  89	BUG_ON(id < MIN_PERNET_OPS_ID);
  90
  91	old_ng = rcu_dereference_protected(net->gen,
  92					   lockdep_is_held(&pernet_ops_rwsem));
  93	if (old_ng->s.len > id) {
  94		old_ng->ptr[id] = data;
  95		return 0;
  96	}
  97
  98	ng = net_alloc_generic();
  99	if (!ng)
 100		return -ENOMEM;
 101
 102	/*
 103	 * Some synchronisation notes:
 104	 *
 105	 * The net_generic explores the net->gen array inside rcu
 106	 * read section. Besides once set the net->gen->ptr[x]
 107	 * pointer never changes (see rules in netns/generic.h).
 108	 *
 109	 * That said, we simply duplicate this array and schedule
 110	 * the old copy for kfree after a grace period.
 111	 */
 112
 113	memcpy(&ng->ptr[MIN_PERNET_OPS_ID], &old_ng->ptr[MIN_PERNET_OPS_ID],
 114	       (old_ng->s.len - MIN_PERNET_OPS_ID) * sizeof(void *));
 115	ng->ptr[id] = data;
 116
 117	rcu_assign_pointer(net->gen, ng);
 118	kfree_rcu(old_ng, s.rcu);
 119	return 0;
 120}
 121
 122static int ops_init(const struct pernet_operations *ops, struct net *net)
 123{
 124	struct net_generic *ng;
 125	int err = -ENOMEM;
 126	void *data = NULL;
 127
 128	if (ops->id && ops->size) {
 129		data = kzalloc(ops->size, GFP_KERNEL);
 130		if (!data)
 131			goto out;
 132
 133		err = net_assign_generic(net, *ops->id, data);
 134		if (err)
 135			goto cleanup;
 136	}
 137	err = 0;
 138	if (ops->init)
 139		err = ops->init(net);
 140	if (!err)
 141		return 0;
 142
 143	if (ops->id && ops->size) {
 144		ng = rcu_dereference_protected(net->gen,
 145					       lockdep_is_held(&pernet_ops_rwsem));
 146		ng->ptr[*ops->id] = NULL;
 147	}
 148
 149cleanup:
 150	kfree(data);
 151
 152out:
 153	return err;
 154}
 155
 156static void ops_pre_exit_list(const struct pernet_operations *ops,
 157			      struct list_head *net_exit_list)
 158{
 159	struct net *net;
 160
 161	if (ops->pre_exit) {
 162		list_for_each_entry(net, net_exit_list, exit_list)
 163			ops->pre_exit(net);
 164	}
 165}
 166
 167static void ops_exit_list(const struct pernet_operations *ops,
 168			  struct list_head *net_exit_list)
 169{
 170	struct net *net;
 171	if (ops->exit) {
 172		list_for_each_entry(net, net_exit_list, exit_list) {
 173			ops->exit(net);
 174			cond_resched();
 175		}
 176	}
 177	if (ops->exit_batch)
 178		ops->exit_batch(net_exit_list);
 179}
 180
 181static void ops_free_list(const struct pernet_operations *ops,
 182			  struct list_head *net_exit_list)
 183{
 184	struct net *net;
 185	if (ops->size && ops->id) {
 186		list_for_each_entry(net, net_exit_list, exit_list)
 187			kfree(net_generic(net, *ops->id));
 188	}
 189}
 190
 191/* should be called with nsid_lock held */
 192static int alloc_netid(struct net *net, struct net *peer, int reqid)
 193{
 194	int min = 0, max = 0;
 195
 196	if (reqid >= 0) {
 197		min = reqid;
 198		max = reqid + 1;
 199	}
 200
 201	return idr_alloc(&net->netns_ids, peer, min, max, GFP_ATOMIC);
 202}
 203
 204/* This function is used by idr_for_each(). If net is equal to peer, the
 205 * function returns the id so that idr_for_each() stops. Because we cannot
 206 * returns the id 0 (idr_for_each() will not stop), we return the magic value
 207 * NET_ID_ZERO (-1) for it.
 208 */
 209#define NET_ID_ZERO -1
 210static int net_eq_idr(int id, void *net, void *peer)
 211{
 212	if (net_eq(net, peer))
 213		return id ? : NET_ID_ZERO;
 214	return 0;
 215}
 216
 217/* Must be called from RCU-critical section or with nsid_lock held */
 218static int __peernet2id(const struct net *net, struct net *peer)
 219{
 220	int id = idr_for_each(&net->netns_ids, net_eq_idr, peer);
 221
 222	/* Magic value for id 0. */
 223	if (id == NET_ID_ZERO)
 224		return 0;
 225	if (id > 0)
 226		return id;
 227
 228	return NETNSA_NSID_NOT_ASSIGNED;
 229}
 230
 231static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid,
 232			      struct nlmsghdr *nlh, gfp_t gfp);
 233/* This function returns the id of a peer netns. If no id is assigned, one will
 234 * be allocated and returned.
 235 */
 236int peernet2id_alloc(struct net *net, struct net *peer, gfp_t gfp)
 237{
 238	int id;
 239
 240	if (refcount_read(&net->ns.count) == 0)
 241		return NETNSA_NSID_NOT_ASSIGNED;
 242
 243	spin_lock_bh(&net->nsid_lock);
 244	id = __peernet2id(net, peer);
 245	if (id >= 0) {
 246		spin_unlock_bh(&net->nsid_lock);
 247		return id;
 248	}
 249
 250	/* When peer is obtained from RCU lists, we may race with
 251	 * its cleanup. Check whether it's alive, and this guarantees
 252	 * we never hash a peer back to net->netns_ids, after it has
 253	 * just been idr_remove()'d from there in cleanup_net().
 254	 */
 255	if (!maybe_get_net(peer)) {
 256		spin_unlock_bh(&net->nsid_lock);
 257		return NETNSA_NSID_NOT_ASSIGNED;
 258	}
 259
 260	id = alloc_netid(net, peer, -1);
 261	spin_unlock_bh(&net->nsid_lock);
 262
 263	put_net(peer);
 264	if (id < 0)
 265		return NETNSA_NSID_NOT_ASSIGNED;
 266
 267	rtnl_net_notifyid(net, RTM_NEWNSID, id, 0, NULL, gfp);
 268
 269	return id;
 270}
 271EXPORT_SYMBOL_GPL(peernet2id_alloc);
 272
 273/* This function returns, if assigned, the id of a peer netns. */
 274int peernet2id(const struct net *net, struct net *peer)
 275{
 276	int id;
 277
 278	rcu_read_lock();
 279	id = __peernet2id(net, peer);
 280	rcu_read_unlock();
 281
 282	return id;
 283}
 284EXPORT_SYMBOL(peernet2id);
 285
 286/* This function returns true is the peer netns has an id assigned into the
 287 * current netns.
 288 */
 289bool peernet_has_id(const struct net *net, struct net *peer)
 290{
 291	return peernet2id(net, peer) >= 0;
 292}
 293
 294struct net *get_net_ns_by_id(const struct net *net, int id)
 295{
 296	struct net *peer;
 297
 298	if (id < 0)
 299		return NULL;
 300
 301	rcu_read_lock();
 302	peer = idr_find(&net->netns_ids, id);
 303	if (peer)
 304		peer = maybe_get_net(peer);
 305	rcu_read_unlock();
 306
 307	return peer;
 308}
 309EXPORT_SYMBOL_GPL(get_net_ns_by_id);
 310
 311/* init code that must occur even if setup_net() is not called. */
 312static __net_init void preinit_net(struct net *net)
 313{
 314	ref_tracker_dir_init(&net->notrefcnt_tracker, 128, "net notrefcnt");
 315}
 316
 317/*
 318 * setup_net runs the initializers for the network namespace object.
 319 */
 320static __net_init int setup_net(struct net *net, struct user_namespace *user_ns)
 321{
 322	/* Must be called with pernet_ops_rwsem held */
 323	const struct pernet_operations *ops, *saved_ops;
 324	LIST_HEAD(net_exit_list);
 325	LIST_HEAD(dev_kill_list);
 326	int error = 0;
 
 327
 328	refcount_set(&net->ns.count, 1);
 329	ref_tracker_dir_init(&net->refcnt_tracker, 128, "net refcnt");
 330
 331	refcount_set(&net->passive, 1);
 332	get_random_bytes(&net->hash_mix, sizeof(u32));
 333	preempt_disable();
 334	net->net_cookie = gen_cookie_next(&net_cookie);
 335	preempt_enable();
 336	net->dev_base_seq = 1;
 337	net->user_ns = user_ns;
 338	idr_init(&net->netns_ids);
 339	spin_lock_init(&net->nsid_lock);
 340	mutex_init(&net->ipv4.ra_mutex);
 341
 342	list_for_each_entry(ops, &pernet_list, list) {
 343		error = ops_init(ops, net);
 344		if (error < 0)
 345			goto out_undo;
 346	}
 347	down_write(&net_rwsem);
 348	list_add_tail_rcu(&net->list, &net_namespace_list);
 349	up_write(&net_rwsem);
 350out:
 351	return error;
 352
 353out_undo:
 354	/* Walk through the list backwards calling the exit functions
 355	 * for the pernet modules whose init functions did not fail.
 356	 */
 357	list_add(&net->exit_list, &net_exit_list);
 358	saved_ops = ops;
 359	list_for_each_entry_continue_reverse(ops, &pernet_list, list)
 360		ops_pre_exit_list(ops, &net_exit_list);
 361
 362	synchronize_rcu();
 363
 364	ops = saved_ops;
 365	rtnl_lock();
 366	list_for_each_entry_continue_reverse(ops, &pernet_list, list) {
 367		if (ops->exit_batch_rtnl)
 368			ops->exit_batch_rtnl(&net_exit_list, &dev_kill_list);
 369	}
 370	unregister_netdevice_many(&dev_kill_list);
 371	rtnl_unlock();
 372
 373	ops = saved_ops;
 374	list_for_each_entry_continue_reverse(ops, &pernet_list, list)
 375		ops_exit_list(ops, &net_exit_list);
 376
 377	ops = saved_ops;
 378	list_for_each_entry_continue_reverse(ops, &pernet_list, list)
 379		ops_free_list(ops, &net_exit_list);
 380
 381	rcu_barrier();
 382	goto out;
 383}
 384
 385static int __net_init net_defaults_init_net(struct net *net)
 386{
 387	net->core.sysctl_somaxconn = SOMAXCONN;
 388	/* Limits per socket sk_omem_alloc usage.
 389	 * TCP zerocopy regular usage needs 128 KB.
 390	 */
 391	net->core.sysctl_optmem_max = 128 * 1024;
 392	net->core.sysctl_txrehash = SOCK_TXREHASH_ENABLED;
 393
 394	return 0;
 395}
 396
 397static struct pernet_operations net_defaults_ops = {
 398	.init = net_defaults_init_net,
 399};
 400
 401static __init int net_defaults_init(void)
 402{
 403	if (register_pernet_subsys(&net_defaults_ops))
 404		panic("Cannot initialize net default settings");
 405
 406	return 0;
 407}
 408
 409core_initcall(net_defaults_init);
 410
 411#ifdef CONFIG_NET_NS
 412static struct ucounts *inc_net_namespaces(struct user_namespace *ns)
 413{
 414	return inc_ucount(ns, current_euid(), UCOUNT_NET_NAMESPACES);
 415}
 416
 417static void dec_net_namespaces(struct ucounts *ucounts)
 418{
 419	dec_ucount(ucounts, UCOUNT_NET_NAMESPACES);
 420}
 421
 422static struct kmem_cache *net_cachep __ro_after_init;
 423static struct workqueue_struct *netns_wq;
 424
 425static struct net *net_alloc(void)
 426{
 427	struct net *net = NULL;
 428	struct net_generic *ng;
 429
 430	ng = net_alloc_generic();
 431	if (!ng)
 432		goto out;
 433
 434	net = kmem_cache_zalloc(net_cachep, GFP_KERNEL);
 435	if (!net)
 436		goto out_free;
 437
 438#ifdef CONFIG_KEYS
 439	net->key_domain = kzalloc(sizeof(struct key_tag), GFP_KERNEL);
 440	if (!net->key_domain)
 441		goto out_free_2;
 442	refcount_set(&net->key_domain->usage, 1);
 443#endif
 444
 445	rcu_assign_pointer(net->gen, ng);
 446out:
 447	return net;
 448
 449#ifdef CONFIG_KEYS
 450out_free_2:
 451	kmem_cache_free(net_cachep, net);
 452	net = NULL;
 453#endif
 454out_free:
 455	kfree(ng);
 456	goto out;
 457}
 458
 459static void net_free(struct net *net)
 460{
 461	if (refcount_dec_and_test(&net->passive)) {
 462		kfree(rcu_access_pointer(net->gen));
 463
 464		/* There should not be any trackers left there. */
 465		ref_tracker_dir_exit(&net->notrefcnt_tracker);
 466
 467		kmem_cache_free(net_cachep, net);
 468	}
 469}
 470
 471void net_drop_ns(void *p)
 472{
 473	struct net *net = (struct net *)p;
 474
 475	if (net)
 476		net_free(net);
 477}
 478
 479struct net *copy_net_ns(unsigned long flags,
 480			struct user_namespace *user_ns, struct net *old_net)
 481{
 482	struct ucounts *ucounts;
 483	struct net *net;
 484	int rv;
 485
 486	if (!(flags & CLONE_NEWNET))
 487		return get_net(old_net);
 488
 489	ucounts = inc_net_namespaces(user_ns);
 490	if (!ucounts)
 491		return ERR_PTR(-ENOSPC);
 492
 493	net = net_alloc();
 494	if (!net) {
 495		rv = -ENOMEM;
 496		goto dec_ucounts;
 497	}
 498
 499	preinit_net(net);
 500	refcount_set(&net->passive, 1);
 501	net->ucounts = ucounts;
 502	get_user_ns(user_ns);
 503
 504	rv = down_read_killable(&pernet_ops_rwsem);
 505	if (rv < 0)
 506		goto put_userns;
 507
 508	rv = setup_net(net, user_ns);
 509
 510	up_read(&pernet_ops_rwsem);
 511
 512	if (rv < 0) {
 513put_userns:
 514#ifdef CONFIG_KEYS
 515		key_remove_domain(net->key_domain);
 516#endif
 517		put_user_ns(user_ns);
 518		net_free(net);
 519dec_ucounts:
 520		dec_net_namespaces(ucounts);
 521		return ERR_PTR(rv);
 522	}
 523	return net;
 524}
 525
 526/**
 527 * net_ns_get_ownership - get sysfs ownership data for @net
 528 * @net: network namespace in question (can be NULL)
 529 * @uid: kernel user ID for sysfs objects
 530 * @gid: kernel group ID for sysfs objects
 531 *
 532 * Returns the uid/gid pair of root in the user namespace associated with the
 533 * given network namespace.
 534 */
 535void net_ns_get_ownership(const struct net *net, kuid_t *uid, kgid_t *gid)
 536{
 537	if (net) {
 538		kuid_t ns_root_uid = make_kuid(net->user_ns, 0);
 539		kgid_t ns_root_gid = make_kgid(net->user_ns, 0);
 540
 541		if (uid_valid(ns_root_uid))
 542			*uid = ns_root_uid;
 543
 544		if (gid_valid(ns_root_gid))
 545			*gid = ns_root_gid;
 546	} else {
 547		*uid = GLOBAL_ROOT_UID;
 548		*gid = GLOBAL_ROOT_GID;
 549	}
 550}
 551EXPORT_SYMBOL_GPL(net_ns_get_ownership);
 552
 553static void unhash_nsid(struct net *net, struct net *last)
 554{
 555	struct net *tmp;
 556	/* This function is only called from cleanup_net() work,
 557	 * and this work is the only process, that may delete
 558	 * a net from net_namespace_list. So, when the below
 559	 * is executing, the list may only grow. Thus, we do not
 560	 * use for_each_net_rcu() or net_rwsem.
 561	 */
 562	for_each_net(tmp) {
 563		int id;
 564
 565		spin_lock_bh(&tmp->nsid_lock);
 566		id = __peernet2id(tmp, net);
 567		if (id >= 0)
 568			idr_remove(&tmp->netns_ids, id);
 569		spin_unlock_bh(&tmp->nsid_lock);
 570		if (id >= 0)
 571			rtnl_net_notifyid(tmp, RTM_DELNSID, id, 0, NULL,
 572					  GFP_KERNEL);
 573		if (tmp == last)
 574			break;
 575	}
 576	spin_lock_bh(&net->nsid_lock);
 577	idr_destroy(&net->netns_ids);
 578	spin_unlock_bh(&net->nsid_lock);
 579}
 580
 581static LLIST_HEAD(cleanup_list);
 582
 583static void cleanup_net(struct work_struct *work)
 584{
 585	const struct pernet_operations *ops;
 586	struct net *net, *tmp, *last;
 587	struct llist_node *net_kill_list;
 588	LIST_HEAD(net_exit_list);
 589	LIST_HEAD(dev_kill_list);
 590
 591	/* Atomically snapshot the list of namespaces to cleanup */
 592	net_kill_list = llist_del_all(&cleanup_list);
 593
 594	down_read(&pernet_ops_rwsem);
 595
 596	/* Don't let anyone else find us. */
 597	down_write(&net_rwsem);
 598	llist_for_each_entry(net, net_kill_list, cleanup_list)
 599		list_del_rcu(&net->list);
 600	/* Cache last net. After we unlock rtnl, no one new net
 601	 * added to net_namespace_list can assign nsid pointer
 602	 * to a net from net_kill_list (see peernet2id_alloc()).
 603	 * So, we skip them in unhash_nsid().
 604	 *
 605	 * Note, that unhash_nsid() does not delete nsid links
 606	 * between net_kill_list's nets, as they've already
 607	 * deleted from net_namespace_list. But, this would be
 608	 * useless anyway, as netns_ids are destroyed there.
 609	 */
 610	last = list_last_entry(&net_namespace_list, struct net, list);
 611	up_write(&net_rwsem);
 612
 613	llist_for_each_entry(net, net_kill_list, cleanup_list) {
 614		unhash_nsid(net, last);
 615		list_add_tail(&net->exit_list, &net_exit_list);
 616	}
 617
 618	/* Run all of the network namespace pre_exit methods */
 619	list_for_each_entry_reverse(ops, &pernet_list, list)
 620		ops_pre_exit_list(ops, &net_exit_list);
 621
 622	/*
 623	 * Another CPU might be rcu-iterating the list, wait for it.
 624	 * This needs to be before calling the exit() notifiers, so
 625	 * the rcu_barrier() below isn't sufficient alone.
 626	 * Also the pre_exit() and exit() methods need this barrier.
 627	 */
 628	synchronize_rcu_expedited();
 629
 630	rtnl_lock();
 631	list_for_each_entry_reverse(ops, &pernet_list, list) {
 632		if (ops->exit_batch_rtnl)
 633			ops->exit_batch_rtnl(&net_exit_list, &dev_kill_list);
 634	}
 635	unregister_netdevice_many(&dev_kill_list);
 636	rtnl_unlock();
 637
 638	/* Run all of the network namespace exit methods */
 639	list_for_each_entry_reverse(ops, &pernet_list, list)
 640		ops_exit_list(ops, &net_exit_list);
 641
 642	/* Free the net generic variables */
 643	list_for_each_entry_reverse(ops, &pernet_list, list)
 644		ops_free_list(ops, &net_exit_list);
 645
 646	up_read(&pernet_ops_rwsem);
 647
 648	/* Ensure there are no outstanding rcu callbacks using this
 649	 * network namespace.
 650	 */
 651	rcu_barrier();
 652
 653	/* Finally it is safe to free my network namespace structure */
 654	list_for_each_entry_safe(net, tmp, &net_exit_list, exit_list) {
 655		list_del_init(&net->exit_list);
 656		dec_net_namespaces(net->ucounts);
 657#ifdef CONFIG_KEYS
 658		key_remove_domain(net->key_domain);
 659#endif
 660		put_user_ns(net->user_ns);
 661		net_free(net);
 662	}
 663}
 664
 665/**
 666 * net_ns_barrier - wait until concurrent net_cleanup_work is done
 667 *
 668 * cleanup_net runs from work queue and will first remove namespaces
 669 * from the global list, then run net exit functions.
 670 *
 671 * Call this in module exit path to make sure that all netns
 672 * ->exit ops have been invoked before the function is removed.
 673 */
 674void net_ns_barrier(void)
 675{
 676	down_write(&pernet_ops_rwsem);
 677	up_write(&pernet_ops_rwsem);
 678}
 679EXPORT_SYMBOL(net_ns_barrier);
 680
 681static DECLARE_WORK(net_cleanup_work, cleanup_net);
 682
 683void __put_net(struct net *net)
 684{
 685	ref_tracker_dir_exit(&net->refcnt_tracker);
 686	/* Cleanup the network namespace in process context */
 687	if (llist_add(&net->cleanup_list, &cleanup_list))
 688		queue_work(netns_wq, &net_cleanup_work);
 689}
 690EXPORT_SYMBOL_GPL(__put_net);
 691
 692/**
 693 * get_net_ns - increment the refcount of the network namespace
 694 * @ns: common namespace (net)
 695 *
 696 * Returns the net's common namespace.
 697 */
 698struct ns_common *get_net_ns(struct ns_common *ns)
 699{
 700	return &get_net(container_of(ns, struct net, ns))->ns;
 701}
 702EXPORT_SYMBOL_GPL(get_net_ns);
 703
 704struct net *get_net_ns_by_fd(int fd)
 705{
 706	struct fd f = fdget(fd);
 707	struct net *net = ERR_PTR(-EINVAL);
 708
 709	if (!f.file)
 710		return ERR_PTR(-EBADF);
 711
 712	if (proc_ns_file(f.file)) {
 713		struct ns_common *ns = get_proc_ns(file_inode(f.file));
 714		if (ns->ops == &netns_operations)
 715			net = get_net(container_of(ns, struct net, ns));
 716	}
 717	fdput(f);
 718
 719	return net;
 720}
 721EXPORT_SYMBOL_GPL(get_net_ns_by_fd);
 722#endif
 723
 724struct net *get_net_ns_by_pid(pid_t pid)
 725{
 726	struct task_struct *tsk;
 727	struct net *net;
 728
 729	/* Lookup the network namespace */
 730	net = ERR_PTR(-ESRCH);
 731	rcu_read_lock();
 732	tsk = find_task_by_vpid(pid);
 733	if (tsk) {
 734		struct nsproxy *nsproxy;
 735		task_lock(tsk);
 736		nsproxy = tsk->nsproxy;
 737		if (nsproxy)
 738			net = get_net(nsproxy->net_ns);
 739		task_unlock(tsk);
 740	}
 741	rcu_read_unlock();
 742	return net;
 743}
 744EXPORT_SYMBOL_GPL(get_net_ns_by_pid);
 745
 746static __net_init int net_ns_net_init(struct net *net)
 747{
 748#ifdef CONFIG_NET_NS
 749	net->ns.ops = &netns_operations;
 750#endif
 751	return ns_alloc_inum(&net->ns);
 752}
 753
 754static __net_exit void net_ns_net_exit(struct net *net)
 755{
 756	ns_free_inum(&net->ns);
 757}
 758
 759static struct pernet_operations __net_initdata net_ns_ops = {
 760	.init = net_ns_net_init,
 761	.exit = net_ns_net_exit,
 762};
 763
 764static const struct nla_policy rtnl_net_policy[NETNSA_MAX + 1] = {
 765	[NETNSA_NONE]		= { .type = NLA_UNSPEC },
 766	[NETNSA_NSID]		= { .type = NLA_S32 },
 767	[NETNSA_PID]		= { .type = NLA_U32 },
 768	[NETNSA_FD]		= { .type = NLA_U32 },
 769	[NETNSA_TARGET_NSID]	= { .type = NLA_S32 },
 770};
 771
 772static int rtnl_net_newid(struct sk_buff *skb, struct nlmsghdr *nlh,
 773			  struct netlink_ext_ack *extack)
 774{
 775	struct net *net = sock_net(skb->sk);
 776	struct nlattr *tb[NETNSA_MAX + 1];
 777	struct nlattr *nla;
 778	struct net *peer;
 779	int nsid, err;
 780
 781	err = nlmsg_parse_deprecated(nlh, sizeof(struct rtgenmsg), tb,
 782				     NETNSA_MAX, rtnl_net_policy, extack);
 783	if (err < 0)
 784		return err;
 785	if (!tb[NETNSA_NSID]) {
 786		NL_SET_ERR_MSG(extack, "nsid is missing");
 787		return -EINVAL;
 788	}
 789	nsid = nla_get_s32(tb[NETNSA_NSID]);
 790
 791	if (tb[NETNSA_PID]) {
 792		peer = get_net_ns_by_pid(nla_get_u32(tb[NETNSA_PID]));
 793		nla = tb[NETNSA_PID];
 794	} else if (tb[NETNSA_FD]) {
 795		peer = get_net_ns_by_fd(nla_get_u32(tb[NETNSA_FD]));
 796		nla = tb[NETNSA_FD];
 797	} else {
 798		NL_SET_ERR_MSG(extack, "Peer netns reference is missing");
 799		return -EINVAL;
 800	}
 801	if (IS_ERR(peer)) {
 802		NL_SET_BAD_ATTR(extack, nla);
 803		NL_SET_ERR_MSG(extack, "Peer netns reference is invalid");
 804		return PTR_ERR(peer);
 805	}
 806
 807	spin_lock_bh(&net->nsid_lock);
 808	if (__peernet2id(net, peer) >= 0) {
 809		spin_unlock_bh(&net->nsid_lock);
 810		err = -EEXIST;
 811		NL_SET_BAD_ATTR(extack, nla);
 812		NL_SET_ERR_MSG(extack,
 813			       "Peer netns already has a nsid assigned");
 814		goto out;
 815	}
 816
 817	err = alloc_netid(net, peer, nsid);
 818	spin_unlock_bh(&net->nsid_lock);
 819	if (err >= 0) {
 820		rtnl_net_notifyid(net, RTM_NEWNSID, err, NETLINK_CB(skb).portid,
 821				  nlh, GFP_KERNEL);
 822		err = 0;
 823	} else if (err == -ENOSPC && nsid >= 0) {
 824		err = -EEXIST;
 825		NL_SET_BAD_ATTR(extack, tb[NETNSA_NSID]);
 826		NL_SET_ERR_MSG(extack, "The specified nsid is already used");
 827	}
 828out:
 829	put_net(peer);
 830	return err;
 831}
 832
 833static int rtnl_net_get_size(void)
 834{
 835	return NLMSG_ALIGN(sizeof(struct rtgenmsg))
 836	       + nla_total_size(sizeof(s32)) /* NETNSA_NSID */
 837	       + nla_total_size(sizeof(s32)) /* NETNSA_CURRENT_NSID */
 838	       ;
 839}
 840
 841struct net_fill_args {
 842	u32 portid;
 843	u32 seq;
 844	int flags;
 845	int cmd;
 846	int nsid;
 847	bool add_ref;
 848	int ref_nsid;
 849};
 850
 851static int rtnl_net_fill(struct sk_buff *skb, struct net_fill_args *args)
 852{
 853	struct nlmsghdr *nlh;
 854	struct rtgenmsg *rth;
 855
 856	nlh = nlmsg_put(skb, args->portid, args->seq, args->cmd, sizeof(*rth),
 857			args->flags);
 858	if (!nlh)
 859		return -EMSGSIZE;
 860
 861	rth = nlmsg_data(nlh);
 862	rth->rtgen_family = AF_UNSPEC;
 863
 864	if (nla_put_s32(skb, NETNSA_NSID, args->nsid))
 865		goto nla_put_failure;
 866
 867	if (args->add_ref &&
 868	    nla_put_s32(skb, NETNSA_CURRENT_NSID, args->ref_nsid))
 869		goto nla_put_failure;
 870
 871	nlmsg_end(skb, nlh);
 872	return 0;
 873
 874nla_put_failure:
 875	nlmsg_cancel(skb, nlh);
 876	return -EMSGSIZE;
 877}
 878
 879static int rtnl_net_valid_getid_req(struct sk_buff *skb,
 880				    const struct nlmsghdr *nlh,
 881				    struct nlattr **tb,
 882				    struct netlink_ext_ack *extack)
 883{
 884	int i, err;
 885
 886	if (!netlink_strict_get_check(skb))
 887		return nlmsg_parse_deprecated(nlh, sizeof(struct rtgenmsg),
 888					      tb, NETNSA_MAX, rtnl_net_policy,
 889					      extack);
 890
 891	err = nlmsg_parse_deprecated_strict(nlh, sizeof(struct rtgenmsg), tb,
 892					    NETNSA_MAX, rtnl_net_policy,
 893					    extack);
 894	if (err)
 895		return err;
 896
 897	for (i = 0; i <= NETNSA_MAX; i++) {
 898		if (!tb[i])
 899			continue;
 900
 901		switch (i) {
 902		case NETNSA_PID:
 903		case NETNSA_FD:
 904		case NETNSA_NSID:
 905		case NETNSA_TARGET_NSID:
 906			break;
 907		default:
 908			NL_SET_ERR_MSG(extack, "Unsupported attribute in peer netns getid request");
 909			return -EINVAL;
 910		}
 911	}
 912
 913	return 0;
 914}
 915
 916static int rtnl_net_getid(struct sk_buff *skb, struct nlmsghdr *nlh,
 917			  struct netlink_ext_ack *extack)
 918{
 919	struct net *net = sock_net(skb->sk);
 920	struct nlattr *tb[NETNSA_MAX + 1];
 921	struct net_fill_args fillargs = {
 922		.portid = NETLINK_CB(skb).portid,
 923		.seq = nlh->nlmsg_seq,
 924		.cmd = RTM_NEWNSID,
 925	};
 926	struct net *peer, *target = net;
 927	struct nlattr *nla;
 928	struct sk_buff *msg;
 929	int err;
 930
 931	err = rtnl_net_valid_getid_req(skb, nlh, tb, extack);
 932	if (err < 0)
 933		return err;
 934	if (tb[NETNSA_PID]) {
 935		peer = get_net_ns_by_pid(nla_get_u32(tb[NETNSA_PID]));
 936		nla = tb[NETNSA_PID];
 937	} else if (tb[NETNSA_FD]) {
 938		peer = get_net_ns_by_fd(nla_get_u32(tb[NETNSA_FD]));
 939		nla = tb[NETNSA_FD];
 940	} else if (tb[NETNSA_NSID]) {
 941		peer = get_net_ns_by_id(net, nla_get_s32(tb[NETNSA_NSID]));
 942		if (!peer)
 943			peer = ERR_PTR(-ENOENT);
 944		nla = tb[NETNSA_NSID];
 945	} else {
 946		NL_SET_ERR_MSG(extack, "Peer netns reference is missing");
 947		return -EINVAL;
 948	}
 949
 950	if (IS_ERR(peer)) {
 951		NL_SET_BAD_ATTR(extack, nla);
 952		NL_SET_ERR_MSG(extack, "Peer netns reference is invalid");
 953		return PTR_ERR(peer);
 954	}
 955
 956	if (tb[NETNSA_TARGET_NSID]) {
 957		int id = nla_get_s32(tb[NETNSA_TARGET_NSID]);
 958
 959		target = rtnl_get_net_ns_capable(NETLINK_CB(skb).sk, id);
 960		if (IS_ERR(target)) {
 961			NL_SET_BAD_ATTR(extack, tb[NETNSA_TARGET_NSID]);
 962			NL_SET_ERR_MSG(extack,
 963				       "Target netns reference is invalid");
 964			err = PTR_ERR(target);
 965			goto out;
 966		}
 967		fillargs.add_ref = true;
 968		fillargs.ref_nsid = peernet2id(net, peer);
 969	}
 970
 971	msg = nlmsg_new(rtnl_net_get_size(), GFP_KERNEL);
 972	if (!msg) {
 973		err = -ENOMEM;
 974		goto out;
 975	}
 976
 977	fillargs.nsid = peernet2id(target, peer);
 978	err = rtnl_net_fill(msg, &fillargs);
 979	if (err < 0)
 980		goto err_out;
 981
 982	err = rtnl_unicast(msg, net, NETLINK_CB(skb).portid);
 983	goto out;
 984
 985err_out:
 986	nlmsg_free(msg);
 987out:
 988	if (fillargs.add_ref)
 989		put_net(target);
 990	put_net(peer);
 991	return err;
 992}
 993
 994struct rtnl_net_dump_cb {
 995	struct net *tgt_net;
 996	struct net *ref_net;
 997	struct sk_buff *skb;
 998	struct net_fill_args fillargs;
 999	int idx;
1000	int s_idx;
1001};
1002
1003/* Runs in RCU-critical section. */
1004static int rtnl_net_dumpid_one(int id, void *peer, void *data)
1005{
1006	struct rtnl_net_dump_cb *net_cb = (struct rtnl_net_dump_cb *)data;
1007	int ret;
1008
1009	if (net_cb->idx < net_cb->s_idx)
1010		goto cont;
1011
1012	net_cb->fillargs.nsid = id;
1013	if (net_cb->fillargs.add_ref)
1014		net_cb->fillargs.ref_nsid = __peernet2id(net_cb->ref_net, peer);
1015	ret = rtnl_net_fill(net_cb->skb, &net_cb->fillargs);
1016	if (ret < 0)
1017		return ret;
1018
1019cont:
1020	net_cb->idx++;
1021	return 0;
1022}
1023
1024static int rtnl_valid_dump_net_req(const struct nlmsghdr *nlh, struct sock *sk,
1025				   struct rtnl_net_dump_cb *net_cb,
1026				   struct netlink_callback *cb)
1027{
1028	struct netlink_ext_ack *extack = cb->extack;
1029	struct nlattr *tb[NETNSA_MAX + 1];
1030	int err, i;
1031
1032	err = nlmsg_parse_deprecated_strict(nlh, sizeof(struct rtgenmsg), tb,
1033					    NETNSA_MAX, rtnl_net_policy,
1034					    extack);
1035	if (err < 0)
1036		return err;
1037
1038	for (i = 0; i <= NETNSA_MAX; i++) {
1039		if (!tb[i])
1040			continue;
1041
1042		if (i == NETNSA_TARGET_NSID) {
1043			struct net *net;
1044
1045			net = rtnl_get_net_ns_capable(sk, nla_get_s32(tb[i]));
1046			if (IS_ERR(net)) {
1047				NL_SET_BAD_ATTR(extack, tb[i]);
1048				NL_SET_ERR_MSG(extack,
1049					       "Invalid target network namespace id");
1050				return PTR_ERR(net);
1051			}
1052			net_cb->fillargs.add_ref = true;
1053			net_cb->ref_net = net_cb->tgt_net;
1054			net_cb->tgt_net = net;
1055		} else {
1056			NL_SET_BAD_ATTR(extack, tb[i]);
1057			NL_SET_ERR_MSG(extack,
1058				       "Unsupported attribute in dump request");
1059			return -EINVAL;
1060		}
1061	}
1062
1063	return 0;
1064}
1065
1066static int rtnl_net_dumpid(struct sk_buff *skb, struct netlink_callback *cb)
1067{
1068	struct rtnl_net_dump_cb net_cb = {
1069		.tgt_net = sock_net(skb->sk),
1070		.skb = skb,
1071		.fillargs = {
1072			.portid = NETLINK_CB(cb->skb).portid,
1073			.seq = cb->nlh->nlmsg_seq,
1074			.flags = NLM_F_MULTI,
1075			.cmd = RTM_NEWNSID,
1076		},
1077		.idx = 0,
1078		.s_idx = cb->args[0],
1079	};
1080	int err = 0;
1081
1082	if (cb->strict_check) {
1083		err = rtnl_valid_dump_net_req(cb->nlh, skb->sk, &net_cb, cb);
1084		if (err < 0)
1085			goto end;
1086	}
1087
1088	rcu_read_lock();
1089	idr_for_each(&net_cb.tgt_net->netns_ids, rtnl_net_dumpid_one, &net_cb);
1090	rcu_read_unlock();
1091
1092	cb->args[0] = net_cb.idx;
1093end:
1094	if (net_cb.fillargs.add_ref)
1095		put_net(net_cb.tgt_net);
1096	return err < 0 ? err : skb->len;
1097}
1098
1099static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid,
1100			      struct nlmsghdr *nlh, gfp_t gfp)
1101{
1102	struct net_fill_args fillargs = {
1103		.portid = portid,
1104		.seq = nlh ? nlh->nlmsg_seq : 0,
1105		.cmd = cmd,
1106		.nsid = id,
1107	};
1108	struct sk_buff *msg;
1109	int err = -ENOMEM;
1110
1111	msg = nlmsg_new(rtnl_net_get_size(), gfp);
1112	if (!msg)
1113		goto out;
1114
1115	err = rtnl_net_fill(msg, &fillargs);
1116	if (err < 0)
1117		goto err_out;
1118
1119	rtnl_notify(msg, net, portid, RTNLGRP_NSID, nlh, gfp);
1120	return;
1121
1122err_out:
1123	nlmsg_free(msg);
1124out:
1125	rtnl_set_sk_err(net, RTNLGRP_NSID, err);
1126}
1127
1128#ifdef CONFIG_NET_NS
1129static void __init netns_ipv4_struct_check(void)
1130{
1131	/* TX readonly hotpath cache lines */
1132	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_tx,
1133				      sysctl_tcp_early_retrans);
1134	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_tx,
1135				      sysctl_tcp_tso_win_divisor);
1136	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_tx,
1137				      sysctl_tcp_tso_rtt_log);
1138	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_tx,
1139				      sysctl_tcp_autocorking);
1140	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_tx,
1141				      sysctl_tcp_min_snd_mss);
1142	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_tx,
1143				      sysctl_tcp_notsent_lowat);
1144	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_tx,
1145				      sysctl_tcp_limit_output_bytes);
1146	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_tx,
1147				      sysctl_tcp_min_rtt_wlen);
1148	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_tx,
1149				      sysctl_tcp_wmem);
1150	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_tx,
1151				      sysctl_ip_fwd_use_pmtu);
1152	CACHELINE_ASSERT_GROUP_SIZE(struct netns_ipv4, netns_ipv4_read_tx, 33);
1153
1154	/* TXRX readonly hotpath cache lines */
1155	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_txrx,
1156				      sysctl_tcp_moderate_rcvbuf);
1157	CACHELINE_ASSERT_GROUP_SIZE(struct netns_ipv4, netns_ipv4_read_txrx, 1);
1158
1159	/* RX readonly hotpath cache line */
1160	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_rx,
1161				      sysctl_ip_early_demux);
1162	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_rx,
1163				      sysctl_tcp_early_demux);
1164	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_rx,
1165				      sysctl_tcp_reordering);
1166	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_rx,
1167				      sysctl_tcp_rmem);
1168	CACHELINE_ASSERT_GROUP_SIZE(struct netns_ipv4, netns_ipv4_read_rx, 18);
1169}
1170#endif
1171
1172void __init net_ns_init(void)
1173{
1174	struct net_generic *ng;
1175
1176#ifdef CONFIG_NET_NS
1177	netns_ipv4_struct_check();
1178	net_cachep = kmem_cache_create("net_namespace", sizeof(struct net),
1179					SMP_CACHE_BYTES,
1180					SLAB_PANIC|SLAB_ACCOUNT, NULL);
1181
1182	/* Create workqueue for cleanup */
1183	netns_wq = create_singlethread_workqueue("netns");
1184	if (!netns_wq)
1185		panic("Could not create netns workq");
1186#endif
1187
1188	ng = net_alloc_generic();
1189	if (!ng)
1190		panic("Could not allocate generic netns");
1191
1192	rcu_assign_pointer(init_net.gen, ng);
1193
1194#ifdef CONFIG_KEYS
1195	init_net.key_domain = &init_net_key_domain;
1196#endif
1197	down_write(&pernet_ops_rwsem);
1198	preinit_net(&init_net);
1199	if (setup_net(&init_net, &init_user_ns))
1200		panic("Could not setup the initial network namespace");
1201
1202	init_net_initialized = true;
1203	up_write(&pernet_ops_rwsem);
1204
1205	if (register_pernet_subsys(&net_ns_ops))
1206		panic("Could not register network namespace subsystems");
1207
1208	rtnl_register(PF_UNSPEC, RTM_NEWNSID, rtnl_net_newid, NULL,
1209		      RTNL_FLAG_DOIT_UNLOCKED);
1210	rtnl_register(PF_UNSPEC, RTM_GETNSID, rtnl_net_getid, rtnl_net_dumpid,
1211		      RTNL_FLAG_DOIT_UNLOCKED);
1212}
1213
1214static void free_exit_list(struct pernet_operations *ops, struct list_head *net_exit_list)
1215{
1216	ops_pre_exit_list(ops, net_exit_list);
1217	synchronize_rcu();
1218
1219	if (ops->exit_batch_rtnl) {
1220		LIST_HEAD(dev_kill_list);
1221
1222		rtnl_lock();
1223		ops->exit_batch_rtnl(net_exit_list, &dev_kill_list);
1224		unregister_netdevice_many(&dev_kill_list);
1225		rtnl_unlock();
1226	}
1227	ops_exit_list(ops, net_exit_list);
1228
1229	ops_free_list(ops, net_exit_list);
1230}
1231
1232#ifdef CONFIG_NET_NS
1233static int __register_pernet_operations(struct list_head *list,
1234					struct pernet_operations *ops)
1235{
1236	struct net *net;
1237	int error;
1238	LIST_HEAD(net_exit_list);
1239
1240	list_add_tail(&ops->list, list);
1241	if (ops->init || (ops->id && ops->size)) {
1242		/* We held write locked pernet_ops_rwsem, and parallel
1243		 * setup_net() and cleanup_net() are not possible.
1244		 */
1245		for_each_net(net) {
1246			error = ops_init(ops, net);
1247			if (error)
1248				goto out_undo;
1249			list_add_tail(&net->exit_list, &net_exit_list);
1250		}
1251	}
1252	return 0;
1253
1254out_undo:
1255	/* If I have an error cleanup all namespaces I initialized */
1256	list_del(&ops->list);
1257	free_exit_list(ops, &net_exit_list);
1258	return error;
1259}
1260
1261static void __unregister_pernet_operations(struct pernet_operations *ops)
1262{
1263	struct net *net;
1264	LIST_HEAD(net_exit_list);
1265
1266	list_del(&ops->list);
1267	/* See comment in __register_pernet_operations() */
1268	for_each_net(net)
1269		list_add_tail(&net->exit_list, &net_exit_list);
1270
1271	free_exit_list(ops, &net_exit_list);
1272}
1273
1274#else
1275
1276static int __register_pernet_operations(struct list_head *list,
1277					struct pernet_operations *ops)
1278{
1279	if (!init_net_initialized) {
1280		list_add_tail(&ops->list, list);
1281		return 0;
1282	}
1283
1284	return ops_init(ops, &init_net);
1285}
1286
1287static void __unregister_pernet_operations(struct pernet_operations *ops)
1288{
1289	if (!init_net_initialized) {
1290		list_del(&ops->list);
1291	} else {
1292		LIST_HEAD(net_exit_list);
1293		list_add(&init_net.exit_list, &net_exit_list);
1294		free_exit_list(ops, &net_exit_list);
1295	}
1296}
1297
1298#endif /* CONFIG_NET_NS */
1299
1300static DEFINE_IDA(net_generic_ids);
1301
1302static int register_pernet_operations(struct list_head *list,
1303				      struct pernet_operations *ops)
1304{
1305	int error;
1306
1307	if (ops->id) {
1308		error = ida_alloc_min(&net_generic_ids, MIN_PERNET_OPS_ID,
1309				GFP_KERNEL);
1310		if (error < 0)
1311			return error;
1312		*ops->id = error;
1313		/* This does not require READ_ONCE as writers already hold
1314		 * pernet_ops_rwsem. But WRITE_ONCE is needed to protect
1315		 * net_alloc_generic.
1316		 */
1317		WRITE_ONCE(max_gen_ptrs, max(max_gen_ptrs, *ops->id + 1));
1318	}
1319	error = __register_pernet_operations(list, ops);
1320	if (error) {
1321		rcu_barrier();
1322		if (ops->id)
1323			ida_free(&net_generic_ids, *ops->id);
1324	}
1325
1326	return error;
1327}
1328
1329static void unregister_pernet_operations(struct pernet_operations *ops)
1330{
1331	__unregister_pernet_operations(ops);
1332	rcu_barrier();
1333	if (ops->id)
1334		ida_free(&net_generic_ids, *ops->id);
1335}
1336
1337/**
1338 *      register_pernet_subsys - register a network namespace subsystem
1339 *	@ops:  pernet operations structure for the subsystem
1340 *
1341 *	Register a subsystem which has init and exit functions
1342 *	that are called when network namespaces are created and
1343 *	destroyed respectively.
1344 *
1345 *	When registered all network namespace init functions are
1346 *	called for every existing network namespace.  Allowing kernel
1347 *	modules to have a race free view of the set of network namespaces.
1348 *
1349 *	When a new network namespace is created all of the init
1350 *	methods are called in the order in which they were registered.
1351 *
1352 *	When a network namespace is destroyed all of the exit methods
1353 *	are called in the reverse of the order with which they were
1354 *	registered.
1355 */
1356int register_pernet_subsys(struct pernet_operations *ops)
1357{
1358	int error;
1359	down_write(&pernet_ops_rwsem);
1360	error =  register_pernet_operations(first_device, ops);
1361	up_write(&pernet_ops_rwsem);
1362	return error;
1363}
1364EXPORT_SYMBOL_GPL(register_pernet_subsys);
1365
1366/**
1367 *      unregister_pernet_subsys - unregister a network namespace subsystem
1368 *	@ops: pernet operations structure to manipulate
1369 *
1370 *	Remove the pernet operations structure from the list to be
1371 *	used when network namespaces are created or destroyed.  In
1372 *	addition run the exit method for all existing network
1373 *	namespaces.
1374 */
1375void unregister_pernet_subsys(struct pernet_operations *ops)
1376{
1377	down_write(&pernet_ops_rwsem);
1378	unregister_pernet_operations(ops);
1379	up_write(&pernet_ops_rwsem);
1380}
1381EXPORT_SYMBOL_GPL(unregister_pernet_subsys);
1382
1383/**
1384 *      register_pernet_device - register a network namespace device
1385 *	@ops:  pernet operations structure for the subsystem
1386 *
1387 *	Register a device which has init and exit functions
1388 *	that are called when network namespaces are created and
1389 *	destroyed respectively.
1390 *
1391 *	When registered all network namespace init functions are
1392 *	called for every existing network namespace.  Allowing kernel
1393 *	modules to have a race free view of the set of network namespaces.
1394 *
1395 *	When a new network namespace is created all of the init
1396 *	methods are called in the order in which they were registered.
1397 *
1398 *	When a network namespace is destroyed all of the exit methods
1399 *	are called in the reverse of the order with which they were
1400 *	registered.
1401 */
1402int register_pernet_device(struct pernet_operations *ops)
1403{
1404	int error;
1405	down_write(&pernet_ops_rwsem);
1406	error = register_pernet_operations(&pernet_list, ops);
1407	if (!error && (first_device == &pernet_list))
1408		first_device = &ops->list;
1409	up_write(&pernet_ops_rwsem);
1410	return error;
1411}
1412EXPORT_SYMBOL_GPL(register_pernet_device);
1413
1414/**
1415 *      unregister_pernet_device - unregister a network namespace netdevice
1416 *	@ops: pernet operations structure to manipulate
1417 *
1418 *	Remove the pernet operations structure from the list to be
1419 *	used when network namespaces are created or destroyed.  In
1420 *	addition run the exit method for all existing network
1421 *	namespaces.
1422 */
1423void unregister_pernet_device(struct pernet_operations *ops)
1424{
1425	down_write(&pernet_ops_rwsem);
1426	if (&ops->list == first_device)
1427		first_device = first_device->next;
1428	unregister_pernet_operations(ops);
1429	up_write(&pernet_ops_rwsem);
1430}
1431EXPORT_SYMBOL_GPL(unregister_pernet_device);
1432
1433#ifdef CONFIG_NET_NS
1434static struct ns_common *netns_get(struct task_struct *task)
1435{
1436	struct net *net = NULL;
1437	struct nsproxy *nsproxy;
1438
1439	task_lock(task);
1440	nsproxy = task->nsproxy;
1441	if (nsproxy)
1442		net = get_net(nsproxy->net_ns);
1443	task_unlock(task);
1444
1445	return net ? &net->ns : NULL;
1446}
1447
1448static inline struct net *to_net_ns(struct ns_common *ns)
1449{
1450	return container_of(ns, struct net, ns);
1451}
1452
1453static void netns_put(struct ns_common *ns)
1454{
1455	put_net(to_net_ns(ns));
1456}
1457
1458static int netns_install(struct nsset *nsset, struct ns_common *ns)
1459{
1460	struct nsproxy *nsproxy = nsset->nsproxy;
1461	struct net *net = to_net_ns(ns);
1462
1463	if (!ns_capable(net->user_ns, CAP_SYS_ADMIN) ||
1464	    !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN))
1465		return -EPERM;
1466
1467	put_net(nsproxy->net_ns);
1468	nsproxy->net_ns = get_net(net);
1469	return 0;
1470}
1471
1472static struct user_namespace *netns_owner(struct ns_common *ns)
1473{
1474	return to_net_ns(ns)->user_ns;
1475}
1476
1477const struct proc_ns_operations netns_operations = {
1478	.name		= "net",
1479	.type		= CLONE_NEWNET,
1480	.get		= netns_get,
1481	.put		= netns_put,
1482	.install	= netns_install,
1483	.owner		= netns_owner,
1484};
1485#endif