xref: /openbmc/linux/net/netfilter/xt_recent.c (revision 1f9f6a78)
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, S_IRUGO | S_IWUSR);
55 module_param(ip_list_gid, uint, S_IRUGO | S_IWUSR);
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 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_old_fops, recent_mt_fops;
110 #endif
111 
112 static u_int32_t hash_rnd __read_mostly;
113 static bool hash_rnd_inited __read_mostly;
114 
115 static inline unsigned int recent_entry_hash4(const union nf_inet_addr *addr)
116 {
117 	return jhash_1word((__force u32)addr->ip, hash_rnd) &
118 	       (ip_list_hash_size - 1);
119 }
120 
121 static inline unsigned int recent_entry_hash6(const union nf_inet_addr *addr)
122 {
123 	return jhash2((u32 *)addr->ip6, ARRAY_SIZE(addr->ip6), hash_rnd) &
124 	       (ip_list_hash_size - 1);
125 }
126 
127 static struct recent_entry *
128 recent_entry_lookup(const struct recent_table *table,
129 		    const union nf_inet_addr *addrp, u_int16_t family,
130 		    u_int8_t ttl)
131 {
132 	struct recent_entry *e;
133 	unsigned int h;
134 
135 	if (family == NFPROTO_IPV4)
136 		h = recent_entry_hash4(addrp);
137 	else
138 		h = recent_entry_hash6(addrp);
139 
140 	list_for_each_entry(e, &table->iphash[h], list)
141 		if (e->family == family &&
142 		    memcmp(&e->addr, addrp, sizeof(e->addr)) == 0 &&
143 		    (ttl == e->ttl || ttl == 0 || e->ttl == 0))
144 			return e;
145 	return NULL;
146 }
147 
148 static void recent_entry_remove(struct recent_table *t, struct recent_entry *e)
149 {
150 	list_del(&e->list);
151 	list_del(&e->lru_list);
152 	kfree(e);
153 	t->entries--;
154 }
155 
156 /*
157  * Drop entries with timestamps older then 'time'.
158  */
159 static void recent_entry_reap(struct recent_table *t, unsigned long time)
160 {
161 	struct recent_entry *e;
162 
163 	/*
164 	 * The head of the LRU list is always the oldest entry.
165 	 */
166 	e = list_entry(t->lru_list.next, struct recent_entry, lru_list);
167 
168 	/*
169 	 * The last time stamp is the most recent.
170 	 */
171 	if (time_after(time, e->stamps[e->index-1]))
172 		recent_entry_remove(t, e);
173 }
174 
175 static struct recent_entry *
176 recent_entry_init(struct recent_table *t, const union nf_inet_addr *addr,
177 		  u_int16_t family, u_int8_t ttl)
178 {
179 	struct recent_entry *e;
180 	unsigned int nstamps_max = t->nstamps_max_mask;
181 
182 	if (t->entries >= ip_list_tot) {
183 		e = list_entry(t->lru_list.next, struct recent_entry, lru_list);
184 		recent_entry_remove(t, e);
185 	}
186 
187 	nstamps_max += 1;
188 	e = kmalloc(sizeof(*e) + sizeof(e->stamps[0]) * nstamps_max,
189 		    GFP_ATOMIC);
190 	if (e == NULL)
191 		return NULL;
192 	memcpy(&e->addr, addr, sizeof(e->addr));
193 	e->ttl       = ttl;
194 	e->stamps[0] = jiffies;
195 	e->nstamps   = 1;
196 	e->index     = 1;
197 	e->family    = family;
198 	if (family == NFPROTO_IPV4)
199 		list_add_tail(&e->list, &t->iphash[recent_entry_hash4(addr)]);
200 	else
201 		list_add_tail(&e->list, &t->iphash[recent_entry_hash6(addr)]);
202 	list_add_tail(&e->lru_list, &t->lru_list);
203 	t->entries++;
204 	return e;
205 }
206 
207 static void recent_entry_update(struct recent_table *t, struct recent_entry *e)
208 {
209 	e->index &= t->nstamps_max_mask;
210 	e->stamps[e->index++] = jiffies;
211 	if (e->index > e->nstamps)
212 		e->nstamps = e->index;
213 	list_move_tail(&e->lru_list, &t->lru_list);
214 }
215 
216 static struct recent_table *recent_table_lookup(struct recent_net *recent_net,
217 						const char *name)
218 {
219 	struct recent_table *t;
220 
221 	list_for_each_entry(t, &recent_net->tables, list)
222 		if (!strcmp(t->name, name))
223 			return t;
224 	return NULL;
225 }
226 
227 static void recent_table_flush(struct recent_table *t)
228 {
229 	struct recent_entry *e, *next;
230 	unsigned int i;
231 
232 	for (i = 0; i < ip_list_hash_size; i++)
233 		list_for_each_entry_safe(e, next, &t->iphash[i], list)
234 			recent_entry_remove(t, e);
235 }
236 
237 static bool
238 recent_mt(const struct sk_buff *skb, struct xt_action_param *par)
239 {
240 	struct net *net = dev_net(par->in ? par->in : par->out);
241 	struct recent_net *recent_net = recent_pernet(net);
242 	const struct xt_recent_mtinfo_v1 *info = par->matchinfo;
243 	struct recent_table *t;
244 	struct recent_entry *e;
245 	union nf_inet_addr addr = {}, addr_mask;
246 	u_int8_t ttl;
247 	bool ret = info->invert;
248 
249 	if (par->family == NFPROTO_IPV4) {
250 		const struct iphdr *iph = ip_hdr(skb);
251 
252 		if (info->side == XT_RECENT_DEST)
253 			addr.ip = iph->daddr;
254 		else
255 			addr.ip = iph->saddr;
256 
257 		ttl = iph->ttl;
258 	} else {
259 		const struct ipv6hdr *iph = ipv6_hdr(skb);
260 
261 		if (info->side == XT_RECENT_DEST)
262 			memcpy(&addr.in6, &iph->daddr, sizeof(addr.in6));
263 		else
264 			memcpy(&addr.in6, &iph->saddr, sizeof(addr.in6));
265 
266 		ttl = iph->hop_limit;
267 	}
268 
269 	/* use TTL as seen before forwarding */
270 	if (par->out != NULL && skb->sk == NULL)
271 		ttl++;
272 
273 	spin_lock_bh(&recent_lock);
274 	t = recent_table_lookup(recent_net, info->name);
275 
276 	nf_inet_addr_mask(&addr, &addr_mask, &t->mask);
277 
278 	e = recent_entry_lookup(t, &addr_mask, par->family,
279 				(info->check_set & XT_RECENT_TTL) ? ttl : 0);
280 	if (e == NULL) {
281 		if (!(info->check_set & XT_RECENT_SET))
282 			goto out;
283 		e = recent_entry_init(t, &addr_mask, par->family, ttl);
284 		if (e == NULL)
285 			par->hotdrop = true;
286 		ret = !ret;
287 		goto out;
288 	}
289 
290 	if (info->check_set & XT_RECENT_SET)
291 		ret = !ret;
292 	else if (info->check_set & XT_RECENT_REMOVE) {
293 		recent_entry_remove(t, e);
294 		ret = !ret;
295 	} else if (info->check_set & (XT_RECENT_CHECK | XT_RECENT_UPDATE)) {
296 		unsigned long time = jiffies - info->seconds * HZ;
297 		unsigned int i, hits = 0;
298 
299 		for (i = 0; i < e->nstamps; i++) {
300 			if (info->seconds && time_after(time, e->stamps[i]))
301 				continue;
302 			if (!info->hit_count || ++hits >= info->hit_count) {
303 				ret = !ret;
304 				break;
305 			}
306 		}
307 
308 		/* info->seconds must be non-zero */
309 		if (info->check_set & XT_RECENT_REAP)
310 			recent_entry_reap(t, time);
311 	}
312 
313 	if (info->check_set & XT_RECENT_SET ||
314 	    (info->check_set & XT_RECENT_UPDATE && ret)) {
315 		recent_entry_update(t, e);
316 		e->ttl = ttl;
317 	}
318 out:
319 	spin_unlock_bh(&recent_lock);
320 	return ret;
321 }
322 
323 static void recent_table_free(void *addr)
324 {
325 	kvfree(addr);
326 }
327 
328 static int recent_mt_check(const struct xt_mtchk_param *par,
329 			   const struct xt_recent_mtinfo_v1 *info)
330 {
331 	struct recent_net *recent_net = recent_pernet(par->net);
332 	struct recent_table *t;
333 #ifdef CONFIG_PROC_FS
334 	struct proc_dir_entry *pde;
335 	kuid_t uid;
336 	kgid_t gid;
337 #endif
338 	unsigned int nstamp_mask;
339 	unsigned int i;
340 	int ret = -EINVAL;
341 	size_t sz;
342 
343 	if (unlikely(!hash_rnd_inited)) {
344 		get_random_bytes(&hash_rnd, sizeof(hash_rnd));
345 		hash_rnd_inited = true;
346 	}
347 	if (info->check_set & ~XT_RECENT_VALID_FLAGS) {
348 		pr_info("Unsupported user space flags (%08x)\n",
349 			info->check_set);
350 		return -EINVAL;
351 	}
352 	if (hweight8(info->check_set &
353 		     (XT_RECENT_SET | XT_RECENT_REMOVE |
354 		      XT_RECENT_CHECK | XT_RECENT_UPDATE)) != 1)
355 		return -EINVAL;
356 	if ((info->check_set & (XT_RECENT_SET | XT_RECENT_REMOVE)) &&
357 	    (info->seconds || info->hit_count ||
358 	    (info->check_set & XT_RECENT_MODIFIERS)))
359 		return -EINVAL;
360 	if ((info->check_set & XT_RECENT_REAP) && !info->seconds)
361 		return -EINVAL;
362 	if (info->hit_count >= XT_RECENT_MAX_NSTAMPS) {
363 		pr_info("hitcount (%u) is larger than allowed maximum (%u)\n",
364 			info->hit_count, XT_RECENT_MAX_NSTAMPS - 1);
365 		return -EINVAL;
366 	}
367 	if (info->name[0] == '\0' ||
368 	    strnlen(info->name, XT_RECENT_NAME_LEN) == XT_RECENT_NAME_LEN)
369 		return -EINVAL;
370 
371 	if (ip_pkt_list_tot && info->hit_count < ip_pkt_list_tot)
372 		nstamp_mask = roundup_pow_of_two(ip_pkt_list_tot) - 1;
373 	else if (info->hit_count)
374 		nstamp_mask = roundup_pow_of_two(info->hit_count) - 1;
375 	else
376 		nstamp_mask = 32 - 1;
377 
378 	mutex_lock(&recent_mutex);
379 	t = recent_table_lookup(recent_net, info->name);
380 	if (t != NULL) {
381 		if (info->hit_count > t->nstamps_max_mask) {
382 			pr_info("hitcount (%u) is larger than packets to be remembered (%u) for table %s\n",
383 				info->hit_count, t->nstamps_max_mask + 1,
384 				info->name);
385 			ret = -EINVAL;
386 			goto out;
387 		}
388 
389 		t->refcnt++;
390 		ret = 0;
391 		goto out;
392 	}
393 
394 	sz = sizeof(*t) + sizeof(t->iphash[0]) * ip_list_hash_size;
395 	if (sz <= PAGE_SIZE)
396 		t = kzalloc(sz, GFP_KERNEL);
397 	else
398 		t = vzalloc(sz);
399 	if (t == NULL) {
400 		ret = -ENOMEM;
401 		goto out;
402 	}
403 	t->refcnt = 1;
404 	t->nstamps_max_mask = nstamp_mask;
405 
406 	memcpy(&t->mask, &info->mask, sizeof(t->mask));
407 	strcpy(t->name, info->name);
408 	INIT_LIST_HEAD(&t->lru_list);
409 	for (i = 0; i < ip_list_hash_size; i++)
410 		INIT_LIST_HEAD(&t->iphash[i]);
411 #ifdef CONFIG_PROC_FS
412 	uid = make_kuid(&init_user_ns, ip_list_uid);
413 	gid = make_kgid(&init_user_ns, ip_list_gid);
414 	if (!uid_valid(uid) || !gid_valid(gid)) {
415 		recent_table_free(t);
416 		ret = -EINVAL;
417 		goto out;
418 	}
419 	pde = proc_create_data(t->name, ip_list_perms, recent_net->xt_recent,
420 		  &recent_mt_fops, t);
421 	if (pde == NULL) {
422 		recent_table_free(t);
423 		ret = -ENOMEM;
424 		goto out;
425 	}
426 	proc_set_user(pde, uid, gid);
427 #endif
428 	spin_lock_bh(&recent_lock);
429 	list_add_tail(&t->list, &recent_net->tables);
430 	spin_unlock_bh(&recent_lock);
431 	ret = 0;
432 out:
433 	mutex_unlock(&recent_mutex);
434 	return ret;
435 }
436 
437 static int recent_mt_check_v0(const struct xt_mtchk_param *par)
438 {
439 	const struct xt_recent_mtinfo_v0 *info_v0 = par->matchinfo;
440 	struct xt_recent_mtinfo_v1 info_v1;
441 
442 	/* Copy revision 0 structure to revision 1 */
443 	memcpy(&info_v1, info_v0, sizeof(struct xt_recent_mtinfo));
444 	/* Set default mask to ensure backward compatible behaviour */
445 	memset(info_v1.mask.all, 0xFF, sizeof(info_v1.mask.all));
446 
447 	return recent_mt_check(par, &info_v1);
448 }
449 
450 static int recent_mt_check_v1(const struct xt_mtchk_param *par)
451 {
452 	return recent_mt_check(par, par->matchinfo);
453 }
454 
455 static void recent_mt_destroy(const struct xt_mtdtor_param *par)
456 {
457 	struct recent_net *recent_net = recent_pernet(par->net);
458 	const struct xt_recent_mtinfo_v1 *info = par->matchinfo;
459 	struct recent_table *t;
460 
461 	mutex_lock(&recent_mutex);
462 	t = recent_table_lookup(recent_net, info->name);
463 	if (--t->refcnt == 0) {
464 		spin_lock_bh(&recent_lock);
465 		list_del(&t->list);
466 		spin_unlock_bh(&recent_lock);
467 #ifdef CONFIG_PROC_FS
468 		if (recent_net->xt_recent != NULL)
469 			remove_proc_entry(t->name, recent_net->xt_recent);
470 #endif
471 		recent_table_flush(t);
472 		recent_table_free(t);
473 	}
474 	mutex_unlock(&recent_mutex);
475 }
476 
477 #ifdef CONFIG_PROC_FS
478 struct recent_iter_state {
479 	const struct recent_table *table;
480 	unsigned int		bucket;
481 };
482 
483 static void *recent_seq_start(struct seq_file *seq, loff_t *pos)
484 	__acquires(recent_lock)
485 {
486 	struct recent_iter_state *st = seq->private;
487 	const struct recent_table *t = st->table;
488 	struct recent_entry *e;
489 	loff_t p = *pos;
490 
491 	spin_lock_bh(&recent_lock);
492 
493 	for (st->bucket = 0; st->bucket < ip_list_hash_size; st->bucket++)
494 		list_for_each_entry(e, &t->iphash[st->bucket], list)
495 			if (p-- == 0)
496 				return e;
497 	return NULL;
498 }
499 
500 static void *recent_seq_next(struct seq_file *seq, void *v, loff_t *pos)
501 {
502 	struct recent_iter_state *st = seq->private;
503 	const struct recent_table *t = st->table;
504 	const struct recent_entry *e = v;
505 	const struct list_head *head = e->list.next;
506 
507 	while (head == &t->iphash[st->bucket]) {
508 		if (++st->bucket >= ip_list_hash_size)
509 			return NULL;
510 		head = t->iphash[st->bucket].next;
511 	}
512 	(*pos)++;
513 	return list_entry(head, struct recent_entry, list);
514 }
515 
516 static void recent_seq_stop(struct seq_file *s, void *v)
517 	__releases(recent_lock)
518 {
519 	spin_unlock_bh(&recent_lock);
520 }
521 
522 static int recent_seq_show(struct seq_file *seq, void *v)
523 {
524 	const struct recent_entry *e = v;
525 	struct recent_iter_state *st = seq->private;
526 	const struct recent_table *t = st->table;
527 	unsigned int i;
528 
529 	i = (e->index - 1) & t->nstamps_max_mask;
530 
531 	if (e->family == NFPROTO_IPV4)
532 		seq_printf(seq, "src=%pI4 ttl: %u last_seen: %lu oldest_pkt: %u",
533 			   &e->addr.ip, e->ttl, e->stamps[i], e->index);
534 	else
535 		seq_printf(seq, "src=%pI6 ttl: %u last_seen: %lu oldest_pkt: %u",
536 			   &e->addr.in6, e->ttl, e->stamps[i], e->index);
537 	for (i = 0; i < e->nstamps; i++)
538 		seq_printf(seq, "%s %lu", i ? "," : "", e->stamps[i]);
539 	seq_printf(seq, "\n");
540 	return 0;
541 }
542 
543 static const struct seq_operations recent_seq_ops = {
544 	.start		= recent_seq_start,
545 	.next		= recent_seq_next,
546 	.stop		= recent_seq_stop,
547 	.show		= recent_seq_show,
548 };
549 
550 static int recent_seq_open(struct inode *inode, struct file *file)
551 {
552 	struct recent_iter_state *st;
553 
554 	st = __seq_open_private(file, &recent_seq_ops, sizeof(*st));
555 	if (st == NULL)
556 		return -ENOMEM;
557 
558 	st->table    = PDE_DATA(inode);
559 	return 0;
560 }
561 
562 static ssize_t
563 recent_mt_proc_write(struct file *file, const char __user *input,
564 		     size_t size, loff_t *loff)
565 {
566 	struct recent_table *t = PDE_DATA(file_inode(file));
567 	struct recent_entry *e;
568 	char buf[sizeof("+b335:1d35:1e55:dead:c0de:1715:5afe:c0de")];
569 	const char *c = buf;
570 	union nf_inet_addr addr = {};
571 	u_int16_t family;
572 	bool add, succ;
573 
574 	if (size == 0)
575 		return 0;
576 	if (size > sizeof(buf))
577 		size = sizeof(buf);
578 	if (copy_from_user(buf, input, size) != 0)
579 		return -EFAULT;
580 
581 	/* Strict protocol! */
582 	if (*loff != 0)
583 		return -ESPIPE;
584 	switch (*c) {
585 	case '/': /* flush table */
586 		spin_lock_bh(&recent_lock);
587 		recent_table_flush(t);
588 		spin_unlock_bh(&recent_lock);
589 		return size;
590 	case '-': /* remove address */
591 		add = false;
592 		break;
593 	case '+': /* add address */
594 		add = true;
595 		break;
596 	default:
597 		pr_info("Need \"+ip\", \"-ip\" or \"/\"\n");
598 		return -EINVAL;
599 	}
600 
601 	++c;
602 	--size;
603 	if (strnchr(c, size, ':') != NULL) {
604 		family = NFPROTO_IPV6;
605 		succ   = in6_pton(c, size, (void *)&addr, '\n', NULL);
606 	} else {
607 		family = NFPROTO_IPV4;
608 		succ   = in4_pton(c, size, (void *)&addr, '\n', NULL);
609 	}
610 
611 	if (!succ) {
612 		pr_info("illegal address written to procfs\n");
613 		return -EINVAL;
614 	}
615 
616 	spin_lock_bh(&recent_lock);
617 	e = recent_entry_lookup(t, &addr, family, 0);
618 	if (e == NULL) {
619 		if (add)
620 			recent_entry_init(t, &addr, family, 0);
621 	} else {
622 		if (add)
623 			recent_entry_update(t, e);
624 		else
625 			recent_entry_remove(t, e);
626 	}
627 	spin_unlock_bh(&recent_lock);
628 	/* Note we removed one above */
629 	*loff += size + 1;
630 	return size + 1;
631 }
632 
633 static const struct file_operations recent_mt_fops = {
634 	.open    = recent_seq_open,
635 	.read    = seq_read,
636 	.write   = recent_mt_proc_write,
637 	.release = seq_release_private,
638 	.owner   = THIS_MODULE,
639 	.llseek = seq_lseek,
640 };
641 
642 static int __net_init recent_proc_net_init(struct net *net)
643 {
644 	struct recent_net *recent_net = recent_pernet(net);
645 
646 	recent_net->xt_recent = proc_mkdir("xt_recent", net->proc_net);
647 	if (!recent_net->xt_recent)
648 		return -ENOMEM;
649 	return 0;
650 }
651 
652 static void __net_exit recent_proc_net_exit(struct net *net)
653 {
654 	struct recent_net *recent_net = recent_pernet(net);
655 	struct recent_table *t;
656 
657 	/* recent_net_exit() is called before recent_mt_destroy(). Make sure
658 	 * that the parent xt_recent proc entry is is empty before trying to
659 	 * remove it.
660 	 */
661 	spin_lock_bh(&recent_lock);
662 	list_for_each_entry(t, &recent_net->tables, list)
663 	        remove_proc_entry(t->name, recent_net->xt_recent);
664 
665 	recent_net->xt_recent = NULL;
666 	spin_unlock_bh(&recent_lock);
667 
668 	remove_proc_entry("xt_recent", net->proc_net);
669 }
670 #else
671 static inline int recent_proc_net_init(struct net *net)
672 {
673 	return 0;
674 }
675 
676 static inline void recent_proc_net_exit(struct net *net)
677 {
678 }
679 #endif /* CONFIG_PROC_FS */
680 
681 static int __net_init recent_net_init(struct net *net)
682 {
683 	struct recent_net *recent_net = recent_pernet(net);
684 
685 	INIT_LIST_HEAD(&recent_net->tables);
686 	return recent_proc_net_init(net);
687 }
688 
689 static void __net_exit recent_net_exit(struct net *net)
690 {
691 	recent_proc_net_exit(net);
692 }
693 
694 static struct pernet_operations recent_net_ops = {
695 	.init	= recent_net_init,
696 	.exit	= recent_net_exit,
697 	.id	= &recent_net_id,
698 	.size	= sizeof(struct recent_net),
699 };
700 
701 static struct xt_match recent_mt_reg[] __read_mostly = {
702 	{
703 		.name       = "recent",
704 		.revision   = 0,
705 		.family     = NFPROTO_IPV4,
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   = 0,
715 		.family     = NFPROTO_IPV6,
716 		.match      = recent_mt,
717 		.matchsize  = sizeof(struct xt_recent_mtinfo),
718 		.checkentry = recent_mt_check_v0,
719 		.destroy    = recent_mt_destroy,
720 		.me         = THIS_MODULE,
721 	},
722 	{
723 		.name       = "recent",
724 		.revision   = 1,
725 		.family     = NFPROTO_IPV4,
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 		.name       = "recent",
734 		.revision   = 1,
735 		.family     = NFPROTO_IPV6,
736 		.match      = recent_mt,
737 		.matchsize  = sizeof(struct xt_recent_mtinfo_v1),
738 		.checkentry = recent_mt_check_v1,
739 		.destroy    = recent_mt_destroy,
740 		.me         = THIS_MODULE,
741 	}
742 };
743 
744 static int __init recent_mt_init(void)
745 {
746 	int err;
747 
748 	BUILD_BUG_ON_NOT_POWER_OF_2(XT_RECENT_MAX_NSTAMPS);
749 
750 	if (!ip_list_tot || ip_pkt_list_tot >= XT_RECENT_MAX_NSTAMPS)
751 		return -EINVAL;
752 	ip_list_hash_size = 1 << fls(ip_list_tot);
753 
754 	err = register_pernet_subsys(&recent_net_ops);
755 	if (err)
756 		return err;
757 	err = xt_register_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
758 	if (err)
759 		unregister_pernet_subsys(&recent_net_ops);
760 	return err;
761 }
762 
763 static void __exit recent_mt_exit(void)
764 {
765 	xt_unregister_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
766 	unregister_pernet_subsys(&recent_net_ops);
767 }
768 
769 module_init(recent_mt_init);
770 module_exit(recent_mt_exit);
771