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