xref: /openbmc/linux/net/netfilter/xt_recent.c (revision ba61bb17) 
1 /*
2  * Copyright (c) 2006 Patrick McHardy <kaber@trash.net>
3  * Copyright © CC Computer Consultants GmbH, 2007 - 2008
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License version 2 as
7  * published by the Free Software Foundation.
8  *
9  * This is a replacement of the old ipt_recent module, which carried the
10  * following copyright notice:
11  *
12  * Author: Stephen Frost <sfrost@snowman.net>
13  * Copyright 2002-2003, Stephen Frost, 2.5.x port by laforge@netfilter.org
14  */
15 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
16 #include <linux/init.h>
17 #include <linux/ip.h>
18 #include <linux/ipv6.h>
19 #include <linux/module.h>
20 #include <linux/moduleparam.h>
21 #include <linux/proc_fs.h>
22 #include <linux/seq_file.h>
23 #include <linux/string.h>
24 #include <linux/ctype.h>
25 #include <linux/list.h>
26 #include <linux/random.h>
27 #include <linux/jhash.h>
28 #include <linux/bitops.h>
29 #include <linux/skbuff.h>
30 #include <linux/inet.h>
31 #include <linux/slab.h>
32 #include <linux/vmalloc.h>
33 #include <net/net_namespace.h>
34 #include <net/netns/generic.h>
35 
36 #include <linux/netfilter/x_tables.h>
37 #include <linux/netfilter/xt_recent.h>
38 
39 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
40 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
41 MODULE_DESCRIPTION("Xtables: \"recently-seen\" host matching");
42 MODULE_LICENSE("GPL");
43 MODULE_ALIAS("ipt_recent");
44 MODULE_ALIAS("ip6t_recent");
45 
46 static unsigned int ip_list_tot __read_mostly = 100;
47 static unsigned int ip_list_hash_size __read_mostly;
48 static unsigned int ip_list_perms __read_mostly = 0644;
49 static unsigned int ip_list_uid __read_mostly;
50 static unsigned int ip_list_gid __read_mostly;
51 module_param(ip_list_tot, uint, 0400);
52 module_param(ip_list_hash_size, uint, 0400);
53 module_param(ip_list_perms, uint, 0400);
54 module_param(ip_list_uid, uint, 0644);
55 module_param(ip_list_gid, uint, 0644);
56 MODULE_PARM_DESC(ip_list_tot, "number of IPs to remember per list");
57 MODULE_PARM_DESC(ip_list_hash_size, "size of hash table used to look up IPs");
58 MODULE_PARM_DESC(ip_list_perms, "permissions on /proc/net/xt_recent/* files");
59 MODULE_PARM_DESC(ip_list_uid, "default owner of /proc/net/xt_recent/* files");
60 MODULE_PARM_DESC(ip_list_gid, "default owning group of /proc/net/xt_recent/* files");
61 
62 /* retained for backwards compatibility */
63 static unsigned int ip_pkt_list_tot __read_mostly;
64 module_param(ip_pkt_list_tot, uint, 0400);
65 MODULE_PARM_DESC(ip_pkt_list_tot, "number of packets per IP address to remember (max. 255)");
66 
67 #define XT_RECENT_MAX_NSTAMPS	256
68 
69 struct recent_entry {
70 	struct list_head	list;
71 	struct list_head	lru_list;
72 	union nf_inet_addr	addr;
73 	u_int16_t		family;
74 	u_int8_t		ttl;
75 	u_int8_t		index;
76 	u_int16_t		nstamps;
77 	unsigned long		stamps[0];
78 };
79 
80 struct recent_table {
81 	struct list_head	list;
82 	char			name[XT_RECENT_NAME_LEN];
83 	union nf_inet_addr	mask;
84 	unsigned int		refcnt;
85 	unsigned int		entries;
86 	u8			nstamps_max_mask;
87 	struct list_head	lru_list;
88 	struct list_head	iphash[0];
89 };
90 
91 struct recent_net {
92 	struct list_head	tables;
93 #ifdef CONFIG_PROC_FS
94 	struct proc_dir_entry	*xt_recent;
95 #endif
96 };
97 
98 static unsigned int recent_net_id __read_mostly;
99 
100 static inline struct recent_net *recent_pernet(struct net *net)
101 {
102 	return net_generic(net, recent_net_id);
103 }
104 
105 static DEFINE_SPINLOCK(recent_lock);
106 static DEFINE_MUTEX(recent_mutex);
107 
108 #ifdef CONFIG_PROC_FS
109 static const struct file_operations recent_mt_fops;
110 #endif
111 
112 static u_int32_t hash_rnd __read_mostly;
113 
114 static inline unsigned int recent_entry_hash4(const union nf_inet_addr *addr)
115 {
116 	return jhash_1word((__force u32)addr->ip, hash_rnd) &
117 	       (ip_list_hash_size - 1);
118 }
119 
120 static inline unsigned int recent_entry_hash6(const union nf_inet_addr *addr)
121 {
122 	return jhash2((u32 *)addr->ip6, ARRAY_SIZE(addr->ip6), hash_rnd) &
123 	       (ip_list_hash_size - 1);
124 }
125 
126 static struct recent_entry *
127 recent_entry_lookup(const struct recent_table *table,
128 		    const union nf_inet_addr *addrp, u_int16_t family,
129 		    u_int8_t ttl)
130 {
131 	struct recent_entry *e;
132 	unsigned int h;
133 
134 	if (family == NFPROTO_IPV4)
135 		h = recent_entry_hash4(addrp);
136 	else
137 		h = recent_entry_hash6(addrp);
138 
139 	list_for_each_entry(e, &table->iphash[h], list)
140 		if (e->family == family &&
141 		    memcmp(&e->addr, addrp, sizeof(e->addr)) == 0 &&
142 		    (ttl == e->ttl || ttl == 0 || e->ttl == 0))
143 			return e;
144 	return NULL;
145 }
146 
147 static void recent_entry_remove(struct recent_table *t, struct recent_entry *e)
148 {
149 	list_del(&e->list);
150 	list_del(&e->lru_list);
151 	kfree(e);
152 	t->entries--;
153 }
154 
155 /*
156  * Drop entries with timestamps older then 'time'.
157  */
158 static void recent_entry_reap(struct recent_table *t, unsigned long time)
159 {
160 	struct recent_entry *e;
161 
162 	/*
163 	 * The head of the LRU list is always the oldest entry.
164 	 */
165 	e = list_entry(t->lru_list.next, struct recent_entry, lru_list);
166 
167 	/*
168 	 * The last time stamp is the most recent.
169 	 */
170 	if (time_after(time, e->stamps[e->index-1]))
171 		recent_entry_remove(t, e);
172 }
173 
174 static struct recent_entry *
175 recent_entry_init(struct recent_table *t, const union nf_inet_addr *addr,
176 		  u_int16_t family, u_int8_t ttl)
177 {
178 	struct recent_entry *e;
179 	unsigned int nstamps_max = t->nstamps_max_mask;
180 
181 	if (t->entries >= ip_list_tot) {
182 		e = list_entry(t->lru_list.next, struct recent_entry, lru_list);
183 		recent_entry_remove(t, e);
184 	}
185 
186 	nstamps_max += 1;
187 	e = kmalloc(struct_size(e, stamps, nstamps_max), GFP_ATOMIC);
188 	if (e == NULL)
189 		return NULL;
190 	memcpy(&e->addr, addr, sizeof(e->addr));
191 	e->ttl       = ttl;
192 	e->stamps[0] = jiffies;
193 	e->nstamps   = 1;
194 	e->index     = 1;
195 	e->family    = family;
196 	if (family == NFPROTO_IPV4)
197 		list_add_tail(&e->list, &t->iphash[recent_entry_hash4(addr)]);
198 	else
199 		list_add_tail(&e->list, &t->iphash[recent_entry_hash6(addr)]);
200 	list_add_tail(&e->lru_list, &t->lru_list);
201 	t->entries++;
202 	return e;
203 }
204 
205 static void recent_entry_update(struct recent_table *t, struct recent_entry *e)
206 {
207 	e->index &= t->nstamps_max_mask;
208 	e->stamps[e->index++] = jiffies;
209 	if (e->index > e->nstamps)
210 		e->nstamps = e->index;
211 	list_move_tail(&e->lru_list, &t->lru_list);
212 }
213 
214 static struct recent_table *recent_table_lookup(struct recent_net *recent_net,
215 						const char *name)
216 {
217 	struct recent_table *t;
218 
219 	list_for_each_entry(t, &recent_net->tables, list)
220 		if (!strcmp(t->name, name))
221 			return t;
222 	return NULL;
223 }
224 
225 static void recent_table_flush(struct recent_table *t)
226 {
227 	struct recent_entry *e, *next;
228 	unsigned int i;
229 
230 	for (i = 0; i < ip_list_hash_size; i++)
231 		list_for_each_entry_safe(e, next, &t->iphash[i], list)
232 			recent_entry_remove(t, e);
233 }
234 
235 static bool
236 recent_mt(const struct sk_buff *skb, struct xt_action_param *par)
237 {
238 	struct net *net = xt_net(par);
239 	struct recent_net *recent_net = recent_pernet(net);
240 	const struct xt_recent_mtinfo_v1 *info = par->matchinfo;
241 	struct recent_table *t;
242 	struct recent_entry *e;
243 	union nf_inet_addr addr = {}, addr_mask;
244 	u_int8_t ttl;
245 	bool ret = info->invert;
246 
247 	if (xt_family(par) == NFPROTO_IPV4) {
248 		const struct iphdr *iph = ip_hdr(skb);
249 
250 		if (info->side == XT_RECENT_DEST)
251 			addr.ip = iph->daddr;
252 		else
253 			addr.ip = iph->saddr;
254 
255 		ttl = iph->ttl;
256 	} else {
257 		const struct ipv6hdr *iph = ipv6_hdr(skb);
258 
259 		if (info->side == XT_RECENT_DEST)
260 			memcpy(&addr.in6, &iph->daddr, sizeof(addr.in6));
261 		else
262 			memcpy(&addr.in6, &iph->saddr, sizeof(addr.in6));
263 
264 		ttl = iph->hop_limit;
265 	}
266 
267 	/* use TTL as seen before forwarding */
268 	if (xt_out(par) != NULL && skb->sk == NULL)
269 		ttl++;
270 
271 	spin_lock_bh(&recent_lock);
272 	t = recent_table_lookup(recent_net, info->name);
273 
274 	nf_inet_addr_mask(&addr, &addr_mask, &t->mask);
275 
276 	e = recent_entry_lookup(t, &addr_mask, xt_family(par),
277 				(info->check_set & XT_RECENT_TTL) ? ttl : 0);
278 	if (e == NULL) {
279 		if (!(info->check_set & XT_RECENT_SET))
280 			goto out;
281 		e = recent_entry_init(t, &addr_mask, xt_family(par), ttl);
282 		if (e == NULL)
283 			par->hotdrop = true;
284 		ret = !ret;
285 		goto out;
286 	}
287 
288 	if (info->check_set & XT_RECENT_SET)
289 		ret = !ret;
290 	else if (info->check_set & XT_RECENT_REMOVE) {
291 		recent_entry_remove(t, e);
292 		ret = !ret;
293 	} else if (info->check_set & (XT_RECENT_CHECK | XT_RECENT_UPDATE)) {
294 		unsigned long time = jiffies - info->seconds * HZ;
295 		unsigned int i, hits = 0;
296 
297 		for (i = 0; i < e->nstamps; i++) {
298 			if (info->seconds && time_after(time, e->stamps[i]))
299 				continue;
300 			if (!info->hit_count || ++hits >= info->hit_count) {
301 				ret = !ret;
302 				break;
303 			}
304 		}
305 
306 		/* info->seconds must be non-zero */
307 		if (info->check_set & XT_RECENT_REAP)
308 			recent_entry_reap(t, time);
309 	}
310 
311 	if (info->check_set & XT_RECENT_SET ||
312 	    (info->check_set & XT_RECENT_UPDATE && ret)) {
313 		recent_entry_update(t, e);
314 		e->ttl = ttl;
315 	}
316 out:
317 	spin_unlock_bh(&recent_lock);
318 	return ret;
319 }
320 
321 static void recent_table_free(void *addr)
322 {
323 	kvfree(addr);
324 }
325 
326 static int recent_mt_check(const struct xt_mtchk_param *par,
327 			   const struct xt_recent_mtinfo_v1 *info)
328 {
329 	struct recent_net *recent_net = recent_pernet(par->net);
330 	struct recent_table *t;
331 #ifdef CONFIG_PROC_FS
332 	struct proc_dir_entry *pde;
333 	kuid_t uid;
334 	kgid_t gid;
335 #endif
336 	unsigned int nstamp_mask;
337 	unsigned int i;
338 	int ret = -EINVAL;
339 	size_t sz;
340 
341 	net_get_random_once(&hash_rnd, sizeof(hash_rnd));
342 
343 	if (info->check_set & ~XT_RECENT_VALID_FLAGS) {
344 		pr_info_ratelimited("Unsupported userspace flags (%08x)\n",
345 				    info->check_set);
346 		return -EINVAL;
347 	}
348 	if (hweight8(info->check_set &
349 		     (XT_RECENT_SET | XT_RECENT_REMOVE |
350 		      XT_RECENT_CHECK | XT_RECENT_UPDATE)) != 1)
351 		return -EINVAL;
352 	if ((info->check_set & (XT_RECENT_SET | XT_RECENT_REMOVE)) &&
353 	    (info->seconds || info->hit_count ||
354 	    (info->check_set & XT_RECENT_MODIFIERS)))
355 		return -EINVAL;
356 	if ((info->check_set & XT_RECENT_REAP) && !info->seconds)
357 		return -EINVAL;
358 	if (info->hit_count >= XT_RECENT_MAX_NSTAMPS) {
359 		pr_info_ratelimited("hitcount (%u) is larger than allowed maximum (%u)\n",
360 				    info->hit_count, XT_RECENT_MAX_NSTAMPS - 1);
361 		return -EINVAL;
362 	}
363 	ret = xt_check_proc_name(info->name, sizeof(info->name));
364 	if (ret)
365 		return ret;
366 
367 	if (ip_pkt_list_tot && info->hit_count < ip_pkt_list_tot)
368 		nstamp_mask = roundup_pow_of_two(ip_pkt_list_tot) - 1;
369 	else if (info->hit_count)
370 		nstamp_mask = roundup_pow_of_two(info->hit_count) - 1;
371 	else
372 		nstamp_mask = 32 - 1;
373 
374 	mutex_lock(&recent_mutex);
375 	t = recent_table_lookup(recent_net, info->name);
376 	if (t != NULL) {
377 		if (nstamp_mask > t->nstamps_max_mask) {
378 			spin_lock_bh(&recent_lock);
379 			recent_table_flush(t);
380 			t->nstamps_max_mask = nstamp_mask;
381 			spin_unlock_bh(&recent_lock);
382 		}
383 
384 		t->refcnt++;
385 		ret = 0;
386 		goto out;
387 	}
388 
389 	sz = sizeof(*t) + sizeof(t->iphash[0]) * ip_list_hash_size;
390 	t = kvzalloc(sz, GFP_KERNEL);
391 	if (t == NULL) {
392 		ret = -ENOMEM;
393 		goto out;
394 	}
395 	t->refcnt = 1;
396 	t->nstamps_max_mask = nstamp_mask;
397 
398 	memcpy(&t->mask, &info->mask, sizeof(t->mask));
399 	strcpy(t->name, info->name);
400 	INIT_LIST_HEAD(&t->lru_list);
401 	for (i = 0; i < ip_list_hash_size; i++)
402 		INIT_LIST_HEAD(&t->iphash[i]);
403 #ifdef CONFIG_PROC_FS
404 	uid = make_kuid(&init_user_ns, ip_list_uid);
405 	gid = make_kgid(&init_user_ns, ip_list_gid);
406 	if (!uid_valid(uid) || !gid_valid(gid)) {
407 		recent_table_free(t);
408 		ret = -EINVAL;
409 		goto out;
410 	}
411 	pde = proc_create_data(t->name, ip_list_perms, recent_net->xt_recent,
412 		  &recent_mt_fops, t);
413 	if (pde == NULL) {
414 		recent_table_free(t);
415 		ret = -ENOMEM;
416 		goto out;
417 	}
418 	proc_set_user(pde, uid, gid);
419 #endif
420 	spin_lock_bh(&recent_lock);
421 	list_add_tail(&t->list, &recent_net->tables);
422 	spin_unlock_bh(&recent_lock);
423 	ret = 0;
424 out:
425 	mutex_unlock(&recent_mutex);
426 	return ret;
427 }
428 
429 static int recent_mt_check_v0(const struct xt_mtchk_param *par)
430 {
431 	const struct xt_recent_mtinfo_v0 *info_v0 = par->matchinfo;
432 	struct xt_recent_mtinfo_v1 info_v1;
433 
434 	/* Copy revision 0 structure to revision 1 */
435 	memcpy(&info_v1, info_v0, sizeof(struct xt_recent_mtinfo));
436 	/* Set default mask to ensure backward compatible behaviour */
437 	memset(info_v1.mask.all, 0xFF, sizeof(info_v1.mask.all));
438 
439 	return recent_mt_check(par, &info_v1);
440 }
441 
442 static int recent_mt_check_v1(const struct xt_mtchk_param *par)
443 {
444 	return recent_mt_check(par, par->matchinfo);
445 }
446 
447 static void recent_mt_destroy(const struct xt_mtdtor_param *par)
448 {
449 	struct recent_net *recent_net = recent_pernet(par->net);
450 	const struct xt_recent_mtinfo_v1 *info = par->matchinfo;
451 	struct recent_table *t;
452 
453 	mutex_lock(&recent_mutex);
454 	t = recent_table_lookup(recent_net, info->name);
455 	if (--t->refcnt == 0) {
456 		spin_lock_bh(&recent_lock);
457 		list_del(&t->list);
458 		spin_unlock_bh(&recent_lock);
459 #ifdef CONFIG_PROC_FS
460 		if (recent_net->xt_recent != NULL)
461 			remove_proc_entry(t->name, recent_net->xt_recent);
462 #endif
463 		recent_table_flush(t);
464 		recent_table_free(t);
465 	}
466 	mutex_unlock(&recent_mutex);
467 }
468 
469 #ifdef CONFIG_PROC_FS
470 struct recent_iter_state {
471 	const struct recent_table *table;
472 	unsigned int		bucket;
473 };
474 
475 static void *recent_seq_start(struct seq_file *seq, loff_t *pos)
476 	__acquires(recent_lock)
477 {
478 	struct recent_iter_state *st = seq->private;
479 	const struct recent_table *t = st->table;
480 	struct recent_entry *e;
481 	loff_t p = *pos;
482 
483 	spin_lock_bh(&recent_lock);
484 
485 	for (st->bucket = 0; st->bucket < ip_list_hash_size; st->bucket++)
486 		list_for_each_entry(e, &t->iphash[st->bucket], list)
487 			if (p-- == 0)
488 				return e;
489 	return NULL;
490 }
491 
492 static void *recent_seq_next(struct seq_file *seq, void *v, loff_t *pos)
493 {
494 	struct recent_iter_state *st = seq->private;
495 	const struct recent_table *t = st->table;
496 	const struct recent_entry *e = v;
497 	const struct list_head *head = e->list.next;
498 
499 	while (head == &t->iphash[st->bucket]) {
500 		if (++st->bucket >= ip_list_hash_size)
501 			return NULL;
502 		head = t->iphash[st->bucket].next;
503 	}
504 	(*pos)++;
505 	return list_entry(head, struct recent_entry, list);
506 }
507 
508 static void recent_seq_stop(struct seq_file *s, void *v)
509 	__releases(recent_lock)
510 {
511 	spin_unlock_bh(&recent_lock);
512 }
513 
514 static int recent_seq_show(struct seq_file *seq, void *v)
515 {
516 	const struct recent_entry *e = v;
517 	struct recent_iter_state *st = seq->private;
518 	const struct recent_table *t = st->table;
519 	unsigned int i;
520 
521 	i = (e->index - 1) & t->nstamps_max_mask;
522 
523 	if (e->family == NFPROTO_IPV4)
524 		seq_printf(seq, "src=%pI4 ttl: %u last_seen: %lu oldest_pkt: %u",
525 			   &e->addr.ip, e->ttl, e->stamps[i], e->index);
526 	else
527 		seq_printf(seq, "src=%pI6 ttl: %u last_seen: %lu oldest_pkt: %u",
528 			   &e->addr.in6, e->ttl, e->stamps[i], e->index);
529 	for (i = 0; i < e->nstamps; i++)
530 		seq_printf(seq, "%s %lu", i ? "," : "", e->stamps[i]);
531 	seq_putc(seq, '\n');
532 	return 0;
533 }
534 
535 static const struct seq_operations recent_seq_ops = {
536 	.start		= recent_seq_start,
537 	.next		= recent_seq_next,
538 	.stop		= recent_seq_stop,
539 	.show		= recent_seq_show,
540 };
541 
542 static int recent_seq_open(struct inode *inode, struct file *file)
543 {
544 	struct recent_iter_state *st;
545 
546 	st = __seq_open_private(file, &recent_seq_ops, sizeof(*st));
547 	if (st == NULL)
548 		return -ENOMEM;
549 
550 	st->table    = PDE_DATA(inode);
551 	return 0;
552 }
553 
554 static ssize_t
555 recent_mt_proc_write(struct file *file, const char __user *input,
556 		     size_t size, loff_t *loff)
557 {
558 	struct recent_table *t = PDE_DATA(file_inode(file));
559 	struct recent_entry *e;
560 	char buf[sizeof("+b335:1d35:1e55:dead:c0de:1715:5afe:c0de")];
561 	const char *c = buf;
562 	union nf_inet_addr addr = {};
563 	u_int16_t family;
564 	bool add, succ;
565 
566 	if (size == 0)
567 		return 0;
568 	if (size > sizeof(buf))
569 		size = sizeof(buf);
570 	if (copy_from_user(buf, input, size) != 0)
571 		return -EFAULT;
572 
573 	/* Strict protocol! */
574 	if (*loff != 0)
575 		return -ESPIPE;
576 	switch (*c) {
577 	case '/': /* flush table */
578 		spin_lock_bh(&recent_lock);
579 		recent_table_flush(t);
580 		spin_unlock_bh(&recent_lock);
581 		return size;
582 	case '-': /* remove address */
583 		add = false;
584 		break;
585 	case '+': /* add address */
586 		add = true;
587 		break;
588 	default:
589 		pr_info_ratelimited("Need \"+ip\", \"-ip\" or \"/\"\n");
590 		return -EINVAL;
591 	}
592 
593 	++c;
594 	--size;
595 	if (strnchr(c, size, ':') != NULL) {
596 		family = NFPROTO_IPV6;
597 		succ   = in6_pton(c, size, (void *)&addr, '\n', NULL);
598 	} else {
599 		family = NFPROTO_IPV4;
600 		succ   = in4_pton(c, size, (void *)&addr, '\n', NULL);
601 	}
602 
603 	if (!succ)
604 		return -EINVAL;
605 
606 	spin_lock_bh(&recent_lock);
607 	e = recent_entry_lookup(t, &addr, family, 0);
608 	if (e == NULL) {
609 		if (add)
610 			recent_entry_init(t, &addr, family, 0);
611 	} else {
612 		if (add)
613 			recent_entry_update(t, e);
614 		else
615 			recent_entry_remove(t, e);
616 	}
617 	spin_unlock_bh(&recent_lock);
618 	/* Note we removed one above */
619 	*loff += size + 1;
620 	return size + 1;
621 }
622 
623 static const struct file_operations recent_mt_fops = {
624 	.open    = recent_seq_open,
625 	.read    = seq_read,
626 	.write   = recent_mt_proc_write,
627 	.release = seq_release_private,
628 	.owner   = THIS_MODULE,
629 	.llseek = seq_lseek,
630 };
631 
632 static int __net_init recent_proc_net_init(struct net *net)
633 {
634 	struct recent_net *recent_net = recent_pernet(net);
635 
636 	recent_net->xt_recent = proc_mkdir("xt_recent", net->proc_net);
637 	if (!recent_net->xt_recent)
638 		return -ENOMEM;
639 	return 0;
640 }
641 
642 static void __net_exit recent_proc_net_exit(struct net *net)
643 {
644 	struct recent_net *recent_net = recent_pernet(net);
645 	struct recent_table *t;
646 
647 	/* recent_net_exit() is called before recent_mt_destroy(). Make sure
648 	 * that the parent xt_recent proc entry is is empty before trying to
649 	 * remove it.
650 	 */
651 	spin_lock_bh(&recent_lock);
652 	list_for_each_entry(t, &recent_net->tables, list)
653 	        remove_proc_entry(t->name, recent_net->xt_recent);
654 
655 	recent_net->xt_recent = NULL;
656 	spin_unlock_bh(&recent_lock);
657 
658 	remove_proc_entry("xt_recent", net->proc_net);
659 }
660 #else
661 static inline int recent_proc_net_init(struct net *net)
662 {
663 	return 0;
664 }
665 
666 static inline void recent_proc_net_exit(struct net *net)
667 {
668 }
669 #endif /* CONFIG_PROC_FS */
670 
671 static int __net_init recent_net_init(struct net *net)
672 {
673 	struct recent_net *recent_net = recent_pernet(net);
674 
675 	INIT_LIST_HEAD(&recent_net->tables);
676 	return recent_proc_net_init(net);
677 }
678 
679 static void __net_exit recent_net_exit(struct net *net)
680 {
681 	recent_proc_net_exit(net);
682 }
683 
684 static struct pernet_operations recent_net_ops = {
685 	.init	= recent_net_init,
686 	.exit	= recent_net_exit,
687 	.id	= &recent_net_id,
688 	.size	= sizeof(struct recent_net),
689 };
690 
691 static struct xt_match recent_mt_reg[] __read_mostly = {
692 	{
693 		.name       = "recent",
694 		.revision   = 0,
695 		.family     = NFPROTO_IPV4,
696 		.match      = recent_mt,
697 		.matchsize  = sizeof(struct xt_recent_mtinfo),
698 		.checkentry = recent_mt_check_v0,
699 		.destroy    = recent_mt_destroy,
700 		.me         = THIS_MODULE,
701 	},
702 	{
703 		.name       = "recent",
704 		.revision   = 0,
705 		.family     = NFPROTO_IPV6,
706 		.match      = recent_mt,
707 		.matchsize  = sizeof(struct xt_recent_mtinfo),
708 		.checkentry = recent_mt_check_v0,
709 		.destroy    = recent_mt_destroy,
710 		.me         = THIS_MODULE,
711 	},
712 	{
713 		.name       = "recent",
714 		.revision   = 1,
715 		.family     = NFPROTO_IPV4,
716 		.match      = recent_mt,
717 		.matchsize  = sizeof(struct xt_recent_mtinfo_v1),
718 		.checkentry = recent_mt_check_v1,
719 		.destroy    = recent_mt_destroy,
720 		.me         = THIS_MODULE,
721 	},
722 	{
723 		.name       = "recent",
724 		.revision   = 1,
725 		.family     = NFPROTO_IPV6,
726 		.match      = recent_mt,
727 		.matchsize  = sizeof(struct xt_recent_mtinfo_v1),
728 		.checkentry = recent_mt_check_v1,
729 		.destroy    = recent_mt_destroy,
730 		.me         = THIS_MODULE,
731 	}
732 };
733 
734 static int __init recent_mt_init(void)
735 {
736 	int err;
737 
738 	BUILD_BUG_ON_NOT_POWER_OF_2(XT_RECENT_MAX_NSTAMPS);
739 
740 	if (!ip_list_tot || ip_pkt_list_tot >= XT_RECENT_MAX_NSTAMPS)
741 		return -EINVAL;
742 	ip_list_hash_size = 1 << fls(ip_list_tot);
743 
744 	err = register_pernet_subsys(&recent_net_ops);
745 	if (err)
746 		return err;
747 	err = xt_register_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
748 	if (err)
749 		unregister_pernet_subsys(&recent_net_ops);
750 	return err;
751 }
752 
753 static void __exit recent_mt_exit(void)
754 {
755 	xt_unregister_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
756 	unregister_pernet_subsys(&recent_net_ops);
757 }
758 
759 module_init(recent_mt_init);
760 module_exit(recent_mt_exit);
761