1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *	xt_hashlimit - Netfilter module to limit the number of packets per time
4  *	separately for each hashbucket (sourceip/sourceport/dstip/dstport)
5  *
6  *	(C) 2003-2004 by Harald Welte <laforge@netfilter.org>
7  *	(C) 2006-2012 Patrick McHardy <kaber@trash.net>
8  *	Copyright © CC Computer Consultants GmbH, 2007 - 2008
9  *
10  * Development of this code was funded by Astaro AG, http://www.astaro.com/
11  */
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13 #include <linux/module.h>
14 #include <linux/spinlock.h>
15 #include <linux/random.h>
16 #include <linux/jhash.h>
17 #include <linux/slab.h>
18 #include <linux/proc_fs.h>
19 #include <linux/seq_file.h>
20 #include <linux/list.h>
21 #include <linux/skbuff.h>
22 #include <linux/mm.h>
23 #include <linux/in.h>
24 #include <linux/ip.h>
25 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
26 #include <linux/ipv6.h>
27 #include <net/ipv6.h>
28 #endif
29 
30 #include <net/net_namespace.h>
31 #include <net/netns/generic.h>
32 
33 #include <linux/netfilter/x_tables.h>
34 #include <linux/netfilter_ipv4/ip_tables.h>
35 #include <linux/netfilter_ipv6/ip6_tables.h>
36 #include <linux/mutex.h>
37 #include <linux/kernel.h>
38 #include <linux/refcount.h>
39 #include <uapi/linux/netfilter/xt_hashlimit.h>
40 
41 #define XT_HASHLIMIT_ALL (XT_HASHLIMIT_HASH_DIP | XT_HASHLIMIT_HASH_DPT | \
42 			  XT_HASHLIMIT_HASH_SIP | XT_HASHLIMIT_HASH_SPT | \
43 			  XT_HASHLIMIT_INVERT | XT_HASHLIMIT_BYTES |\
44 			  XT_HASHLIMIT_RATE_MATCH)
45 
46 MODULE_LICENSE("GPL");
47 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
48 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
49 MODULE_DESCRIPTION("Xtables: per hash-bucket rate-limit match");
50 MODULE_ALIAS("ipt_hashlimit");
51 MODULE_ALIAS("ip6t_hashlimit");
52 
53 struct hashlimit_net {
54 	struct hlist_head	htables;
55 	struct proc_dir_entry	*ipt_hashlimit;
56 	struct proc_dir_entry	*ip6t_hashlimit;
57 };
58 
59 static unsigned int hashlimit_net_id;
60 static inline struct hashlimit_net *hashlimit_pernet(struct net *net)
61 {
62 	return net_generic(net, hashlimit_net_id);
63 }
64 
65 /* need to declare this at the top */
66 static const struct seq_operations dl_seq_ops_v2;
67 static const struct seq_operations dl_seq_ops_v1;
68 static const struct seq_operations dl_seq_ops;
69 
70 /* hash table crap */
71 struct dsthash_dst {
72 	union {
73 		struct {
74 			__be32 src;
75 			__be32 dst;
76 		} ip;
77 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
78 		struct {
79 			__be32 src[4];
80 			__be32 dst[4];
81 		} ip6;
82 #endif
83 	};
84 	__be16 src_port;
85 	__be16 dst_port;
86 };
87 
88 struct dsthash_ent {
89 	/* static / read-only parts in the beginning */
90 	struct hlist_node node;
91 	struct dsthash_dst dst;
92 
93 	/* modified structure members in the end */
94 	spinlock_t lock;
95 	unsigned long expires;		/* precalculated expiry time */
96 	struct {
97 		unsigned long prev;	/* last modification */
98 		union {
99 			struct {
100 				u_int64_t credit;
101 				u_int64_t credit_cap;
102 				u_int64_t cost;
103 			};
104 			struct {
105 				u_int32_t interval, prev_window;
106 				u_int64_t current_rate;
107 				u_int64_t rate;
108 				int64_t burst;
109 			};
110 		};
111 	} rateinfo;
112 	struct rcu_head rcu;
113 };
114 
115 struct xt_hashlimit_htable {
116 	struct hlist_node node;		/* global list of all htables */
117 	refcount_t use;
118 	u_int8_t family;
119 	bool rnd_initialized;
120 
121 	struct hashlimit_cfg3 cfg;	/* config */
122 
123 	/* used internally */
124 	spinlock_t lock;		/* lock for list_head */
125 	u_int32_t rnd;			/* random seed for hash */
126 	unsigned int count;		/* number entries in table */
127 	struct delayed_work gc_work;
128 
129 	/* seq_file stuff */
130 	struct proc_dir_entry *pde;
131 	const char *name;
132 	struct net *net;
133 
134 	struct hlist_head hash[];	/* hashtable itself */
135 };
136 
137 static int
138 cfg_copy(struct hashlimit_cfg3 *to, const void *from, int revision)
139 {
140 	if (revision == 1) {
141 		struct hashlimit_cfg1 *cfg = (struct hashlimit_cfg1 *)from;
142 
143 		to->mode = cfg->mode;
144 		to->avg = cfg->avg;
145 		to->burst = cfg->burst;
146 		to->size = cfg->size;
147 		to->max = cfg->max;
148 		to->gc_interval = cfg->gc_interval;
149 		to->expire = cfg->expire;
150 		to->srcmask = cfg->srcmask;
151 		to->dstmask = cfg->dstmask;
152 	} else if (revision == 2) {
153 		struct hashlimit_cfg2 *cfg = (struct hashlimit_cfg2 *)from;
154 
155 		to->mode = cfg->mode;
156 		to->avg = cfg->avg;
157 		to->burst = cfg->burst;
158 		to->size = cfg->size;
159 		to->max = cfg->max;
160 		to->gc_interval = cfg->gc_interval;
161 		to->expire = cfg->expire;
162 		to->srcmask = cfg->srcmask;
163 		to->dstmask = cfg->dstmask;
164 	} else if (revision == 3) {
165 		memcpy(to, from, sizeof(struct hashlimit_cfg3));
166 	} else {
167 		return -EINVAL;
168 	}
169 
170 	return 0;
171 }
172 
173 static DEFINE_MUTEX(hashlimit_mutex);	/* protects htables list */
174 static struct kmem_cache *hashlimit_cachep __read_mostly;
175 
176 static inline bool dst_cmp(const struct dsthash_ent *ent,
177 			   const struct dsthash_dst *b)
178 {
179 	return !memcmp(&ent->dst, b, sizeof(ent->dst));
180 }
181 
182 static u_int32_t
183 hash_dst(const struct xt_hashlimit_htable *ht, const struct dsthash_dst *dst)
184 {
185 	u_int32_t hash = jhash2((const u32 *)dst,
186 				sizeof(*dst)/sizeof(u32),
187 				ht->rnd);
188 	/*
189 	 * Instead of returning hash % ht->cfg.size (implying a divide)
190 	 * we return the high 32 bits of the (hash * ht->cfg.size) that will
191 	 * give results between [0 and cfg.size-1] and same hash distribution,
192 	 * but using a multiply, less expensive than a divide
193 	 */
194 	return reciprocal_scale(hash, ht->cfg.size);
195 }
196 
197 static struct dsthash_ent *
198 dsthash_find(const struct xt_hashlimit_htable *ht,
199 	     const struct dsthash_dst *dst)
200 {
201 	struct dsthash_ent *ent;
202 	u_int32_t hash = hash_dst(ht, dst);
203 
204 	if (!hlist_empty(&ht->hash[hash])) {
205 		hlist_for_each_entry_rcu(ent, &ht->hash[hash], node)
206 			if (dst_cmp(ent, dst)) {
207 				spin_lock(&ent->lock);
208 				return ent;
209 			}
210 	}
211 	return NULL;
212 }
213 
214 /* allocate dsthash_ent, initialize dst, put in htable and lock it */
215 static struct dsthash_ent *
216 dsthash_alloc_init(struct xt_hashlimit_htable *ht,
217 		   const struct dsthash_dst *dst, bool *race)
218 {
219 	struct dsthash_ent *ent;
220 
221 	spin_lock(&ht->lock);
222 
223 	/* Two or more packets may race to create the same entry in the
224 	 * hashtable, double check if this packet lost race.
225 	 */
226 	ent = dsthash_find(ht, dst);
227 	if (ent != NULL) {
228 		spin_unlock(&ht->lock);
229 		*race = true;
230 		return ent;
231 	}
232 
233 	/* initialize hash with random val at the time we allocate
234 	 * the first hashtable entry */
235 	if (unlikely(!ht->rnd_initialized)) {
236 		get_random_bytes(&ht->rnd, sizeof(ht->rnd));
237 		ht->rnd_initialized = true;
238 	}
239 
240 	if (ht->cfg.max && ht->count >= ht->cfg.max) {
241 		/* FIXME: do something. question is what.. */
242 		net_err_ratelimited("max count of %u reached\n", ht->cfg.max);
243 		ent = NULL;
244 	} else
245 		ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
246 	if (ent) {
247 		memcpy(&ent->dst, dst, sizeof(ent->dst));
248 		spin_lock_init(&ent->lock);
249 
250 		spin_lock(&ent->lock);
251 		hlist_add_head_rcu(&ent->node, &ht->hash[hash_dst(ht, dst)]);
252 		ht->count++;
253 	}
254 	spin_unlock(&ht->lock);
255 	return ent;
256 }
257 
258 static void dsthash_free_rcu(struct rcu_head *head)
259 {
260 	struct dsthash_ent *ent = container_of(head, struct dsthash_ent, rcu);
261 
262 	kmem_cache_free(hashlimit_cachep, ent);
263 }
264 
265 static inline void
266 dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent)
267 {
268 	hlist_del_rcu(&ent->node);
269 	call_rcu(&ent->rcu, dsthash_free_rcu);
270 	ht->count--;
271 }
272 static void htable_gc(struct work_struct *work);
273 
274 static int htable_create(struct net *net, struct hashlimit_cfg3 *cfg,
275 			 const char *name, u_int8_t family,
276 			 struct xt_hashlimit_htable **out_hinfo,
277 			 int revision)
278 {
279 	struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
280 	struct xt_hashlimit_htable *hinfo;
281 	const struct seq_operations *ops;
282 	unsigned int size, i;
283 	unsigned long nr_pages = totalram_pages();
284 	int ret;
285 
286 	if (cfg->size) {
287 		size = cfg->size;
288 	} else {
289 		size = (nr_pages << PAGE_SHIFT) / 16384 /
290 		       sizeof(struct hlist_head);
291 		if (nr_pages > 1024 * 1024 * 1024 / PAGE_SIZE)
292 			size = 8192;
293 		if (size < 16)
294 			size = 16;
295 	}
296 	hinfo = kvmalloc(struct_size(hinfo, hash, size), GFP_KERNEL);
297 	if (hinfo == NULL)
298 		return -ENOMEM;
299 	*out_hinfo = hinfo;
300 
301 	/* copy match config into hashtable config */
302 	ret = cfg_copy(&hinfo->cfg, (void *)cfg, 3);
303 	if (ret) {
304 		kvfree(hinfo);
305 		return ret;
306 	}
307 
308 	hinfo->cfg.size = size;
309 	if (hinfo->cfg.max == 0)
310 		hinfo->cfg.max = 8 * hinfo->cfg.size;
311 	else if (hinfo->cfg.max < hinfo->cfg.size)
312 		hinfo->cfg.max = hinfo->cfg.size;
313 
314 	for (i = 0; i < hinfo->cfg.size; i++)
315 		INIT_HLIST_HEAD(&hinfo->hash[i]);
316 
317 	refcount_set(&hinfo->use, 1);
318 	hinfo->count = 0;
319 	hinfo->family = family;
320 	hinfo->rnd_initialized = false;
321 	hinfo->name = kstrdup(name, GFP_KERNEL);
322 	if (!hinfo->name) {
323 		kvfree(hinfo);
324 		return -ENOMEM;
325 	}
326 	spin_lock_init(&hinfo->lock);
327 
328 	switch (revision) {
329 	case 1:
330 		ops = &dl_seq_ops_v1;
331 		break;
332 	case 2:
333 		ops = &dl_seq_ops_v2;
334 		break;
335 	default:
336 		ops = &dl_seq_ops;
337 	}
338 
339 	hinfo->pde = proc_create_seq_data(name, 0,
340 		(family == NFPROTO_IPV4) ?
341 		hashlimit_net->ipt_hashlimit : hashlimit_net->ip6t_hashlimit,
342 		ops, hinfo);
343 	if (hinfo->pde == NULL) {
344 		kfree(hinfo->name);
345 		kvfree(hinfo);
346 		return -ENOMEM;
347 	}
348 	hinfo->net = net;
349 
350 	INIT_DEFERRABLE_WORK(&hinfo->gc_work, htable_gc);
351 	queue_delayed_work(system_power_efficient_wq, &hinfo->gc_work,
352 			   msecs_to_jiffies(hinfo->cfg.gc_interval));
353 
354 	hlist_add_head(&hinfo->node, &hashlimit_net->htables);
355 
356 	return 0;
357 }
358 
359 static void htable_selective_cleanup(struct xt_hashlimit_htable *ht, bool select_all)
360 {
361 	unsigned int i;
362 
363 	for (i = 0; i < ht->cfg.size; i++) {
364 		struct hlist_head *head = &ht->hash[i];
365 		struct dsthash_ent *dh;
366 		struct hlist_node *n;
367 
368 		if (hlist_empty(head))
369 			continue;
370 
371 		spin_lock_bh(&ht->lock);
372 		hlist_for_each_entry_safe(dh, n, head, node) {
373 			if (time_after_eq(jiffies, dh->expires) || select_all)
374 				dsthash_free(ht, dh);
375 		}
376 		spin_unlock_bh(&ht->lock);
377 		cond_resched();
378 	}
379 }
380 
381 static void htable_gc(struct work_struct *work)
382 {
383 	struct xt_hashlimit_htable *ht;
384 
385 	ht = container_of(work, struct xt_hashlimit_htable, gc_work.work);
386 
387 	htable_selective_cleanup(ht, false);
388 
389 	queue_delayed_work(system_power_efficient_wq,
390 			   &ht->gc_work, msecs_to_jiffies(ht->cfg.gc_interval));
391 }
392 
393 static void htable_remove_proc_entry(struct xt_hashlimit_htable *hinfo)
394 {
395 	struct hashlimit_net *hashlimit_net = hashlimit_pernet(hinfo->net);
396 	struct proc_dir_entry *parent;
397 
398 	if (hinfo->family == NFPROTO_IPV4)
399 		parent = hashlimit_net->ipt_hashlimit;
400 	else
401 		parent = hashlimit_net->ip6t_hashlimit;
402 
403 	if (parent != NULL)
404 		remove_proc_entry(hinfo->name, parent);
405 }
406 
407 static struct xt_hashlimit_htable *htable_find_get(struct net *net,
408 						   const char *name,
409 						   u_int8_t family)
410 {
411 	struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
412 	struct xt_hashlimit_htable *hinfo;
413 
414 	hlist_for_each_entry(hinfo, &hashlimit_net->htables, node) {
415 		if (!strcmp(name, hinfo->name) &&
416 		    hinfo->family == family) {
417 			refcount_inc(&hinfo->use);
418 			return hinfo;
419 		}
420 	}
421 	return NULL;
422 }
423 
424 static void htable_put(struct xt_hashlimit_htable *hinfo)
425 {
426 	if (refcount_dec_and_mutex_lock(&hinfo->use, &hashlimit_mutex)) {
427 		hlist_del(&hinfo->node);
428 		htable_remove_proc_entry(hinfo);
429 		mutex_unlock(&hashlimit_mutex);
430 
431 		cancel_delayed_work_sync(&hinfo->gc_work);
432 		htable_selective_cleanup(hinfo, true);
433 		kfree(hinfo->name);
434 		kvfree(hinfo);
435 	}
436 }
437 
438 /* The algorithm used is the Simple Token Bucket Filter (TBF)
439  * see net/sched/sch_tbf.c in the linux source tree
440  */
441 
442 /* Rusty: This is my (non-mathematically-inclined) understanding of
443    this algorithm.  The `average rate' in jiffies becomes your initial
444    amount of credit `credit' and the most credit you can ever have
445    `credit_cap'.  The `peak rate' becomes the cost of passing the
446    test, `cost'.
447 
448    `prev' tracks the last packet hit: you gain one credit per jiffy.
449    If you get credit balance more than this, the extra credit is
450    discarded.  Every time the match passes, you lose `cost' credits;
451    if you don't have that many, the test fails.
452 
453    See Alexey's formal explanation in net/sched/sch_tbf.c.
454 
455    To get the maximum range, we multiply by this factor (ie. you get N
456    credits per jiffy).  We want to allow a rate as low as 1 per day
457    (slowest userspace tool allows), which means
458    CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
459 */
460 #define MAX_CPJ_v1 (0xFFFFFFFF / (HZ*60*60*24))
461 #define MAX_CPJ (0xFFFFFFFFFFFFFFFFULL / (HZ*60*60*24))
462 
463 /* Repeated shift and or gives us all 1s, final shift and add 1 gives
464  * us the power of 2 below the theoretical max, so GCC simply does a
465  * shift. */
466 #define _POW2_BELOW2(x) ((x)|((x)>>1))
467 #define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
468 #define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
469 #define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
470 #define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
471 #define _POW2_BELOW64(x) (_POW2_BELOW32(x)|_POW2_BELOW32((x)>>32))
472 #define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
473 #define POW2_BELOW64(x) ((_POW2_BELOW64(x)>>1) + 1)
474 
475 #define CREDITS_PER_JIFFY POW2_BELOW64(MAX_CPJ)
476 #define CREDITS_PER_JIFFY_v1 POW2_BELOW32(MAX_CPJ_v1)
477 
478 /* in byte mode, the lowest possible rate is one packet/second.
479  * credit_cap is used as a counter that tells us how many times we can
480  * refill the "credits available" counter when it becomes empty.
481  */
482 #define MAX_CPJ_BYTES (0xFFFFFFFF / HZ)
483 #define CREDITS_PER_JIFFY_BYTES POW2_BELOW32(MAX_CPJ_BYTES)
484 
485 static u32 xt_hashlimit_len_to_chunks(u32 len)
486 {
487 	return (len >> XT_HASHLIMIT_BYTE_SHIFT) + 1;
488 }
489 
490 /* Precision saver. */
491 static u64 user2credits(u64 user, int revision)
492 {
493 	u64 scale = (revision == 1) ?
494 		XT_HASHLIMIT_SCALE : XT_HASHLIMIT_SCALE_v2;
495 	u64 cpj = (revision == 1) ?
496 		CREDITS_PER_JIFFY_v1 : CREDITS_PER_JIFFY;
497 
498 	/* Avoid overflow: divide the constant operands first */
499 	if (scale >= HZ * cpj)
500 		return div64_u64(user, div64_u64(scale, HZ * cpj));
501 
502 	return user * div64_u64(HZ * cpj, scale);
503 }
504 
505 static u32 user2credits_byte(u32 user)
506 {
507 	u64 us = user;
508 	us *= HZ * CREDITS_PER_JIFFY_BYTES;
509 	return (u32) (us >> 32);
510 }
511 
512 static u64 user2rate(u64 user)
513 {
514 	if (user != 0) {
515 		return div64_u64(XT_HASHLIMIT_SCALE_v2, user);
516 	} else {
517 		pr_info_ratelimited("invalid rate from userspace: %llu\n",
518 				    user);
519 		return 0;
520 	}
521 }
522 
523 static u64 user2rate_bytes(u32 user)
524 {
525 	u64 r;
526 
527 	r = user ? U32_MAX / user : U32_MAX;
528 	return (r - 1) << XT_HASHLIMIT_BYTE_SHIFT;
529 }
530 
531 static void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now,
532 			    u32 mode, int revision)
533 {
534 	unsigned long delta = now - dh->rateinfo.prev;
535 	u64 cap, cpj;
536 
537 	if (delta == 0)
538 		return;
539 
540 	if (revision >= 3 && mode & XT_HASHLIMIT_RATE_MATCH) {
541 		u64 interval = dh->rateinfo.interval * HZ;
542 
543 		if (delta < interval)
544 			return;
545 
546 		dh->rateinfo.prev = now;
547 		dh->rateinfo.prev_window =
548 			((dh->rateinfo.current_rate * interval) >
549 			 (delta * dh->rateinfo.rate));
550 		dh->rateinfo.current_rate = 0;
551 
552 		return;
553 	}
554 
555 	dh->rateinfo.prev = now;
556 
557 	if (mode & XT_HASHLIMIT_BYTES) {
558 		u64 tmp = dh->rateinfo.credit;
559 		dh->rateinfo.credit += CREDITS_PER_JIFFY_BYTES * delta;
560 		cap = CREDITS_PER_JIFFY_BYTES * HZ;
561 		if (tmp >= dh->rateinfo.credit) {/* overflow */
562 			dh->rateinfo.credit = cap;
563 			return;
564 		}
565 	} else {
566 		cpj = (revision == 1) ?
567 			CREDITS_PER_JIFFY_v1 : CREDITS_PER_JIFFY;
568 		dh->rateinfo.credit += delta * cpj;
569 		cap = dh->rateinfo.credit_cap;
570 	}
571 	if (dh->rateinfo.credit > cap)
572 		dh->rateinfo.credit = cap;
573 }
574 
575 static void rateinfo_init(struct dsthash_ent *dh,
576 			  struct xt_hashlimit_htable *hinfo, int revision)
577 {
578 	dh->rateinfo.prev = jiffies;
579 	if (revision >= 3 && hinfo->cfg.mode & XT_HASHLIMIT_RATE_MATCH) {
580 		dh->rateinfo.prev_window = 0;
581 		dh->rateinfo.current_rate = 0;
582 		if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) {
583 			dh->rateinfo.rate =
584 				user2rate_bytes((u32)hinfo->cfg.avg);
585 			if (hinfo->cfg.burst)
586 				dh->rateinfo.burst =
587 					hinfo->cfg.burst * dh->rateinfo.rate;
588 			else
589 				dh->rateinfo.burst = dh->rateinfo.rate;
590 		} else {
591 			dh->rateinfo.rate = user2rate(hinfo->cfg.avg);
592 			dh->rateinfo.burst =
593 				hinfo->cfg.burst + dh->rateinfo.rate;
594 		}
595 		dh->rateinfo.interval = hinfo->cfg.interval;
596 	} else if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) {
597 		dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
598 		dh->rateinfo.cost = user2credits_byte(hinfo->cfg.avg);
599 		dh->rateinfo.credit_cap = hinfo->cfg.burst;
600 	} else {
601 		dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
602 						   hinfo->cfg.burst, revision);
603 		dh->rateinfo.cost = user2credits(hinfo->cfg.avg, revision);
604 		dh->rateinfo.credit_cap = dh->rateinfo.credit;
605 	}
606 }
607 
608 static inline __be32 maskl(__be32 a, unsigned int l)
609 {
610 	return l ? htonl(ntohl(a) & ~0 << (32 - l)) : 0;
611 }
612 
613 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
614 static void hashlimit_ipv6_mask(__be32 *i, unsigned int p)
615 {
616 	switch (p) {
617 	case 0 ... 31:
618 		i[0] = maskl(i[0], p);
619 		i[1] = i[2] = i[3] = 0;
620 		break;
621 	case 32 ... 63:
622 		i[1] = maskl(i[1], p - 32);
623 		i[2] = i[3] = 0;
624 		break;
625 	case 64 ... 95:
626 		i[2] = maskl(i[2], p - 64);
627 		i[3] = 0;
628 		break;
629 	case 96 ... 127:
630 		i[3] = maskl(i[3], p - 96);
631 		break;
632 	case 128:
633 		break;
634 	}
635 }
636 #endif
637 
638 static int
639 hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
640 		   struct dsthash_dst *dst,
641 		   const struct sk_buff *skb, unsigned int protoff)
642 {
643 	__be16 _ports[2], *ports;
644 	u8 nexthdr;
645 	int poff;
646 
647 	memset(dst, 0, sizeof(*dst));
648 
649 	switch (hinfo->family) {
650 	case NFPROTO_IPV4:
651 		if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
652 			dst->ip.dst = maskl(ip_hdr(skb)->daddr,
653 			              hinfo->cfg.dstmask);
654 		if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
655 			dst->ip.src = maskl(ip_hdr(skb)->saddr,
656 			              hinfo->cfg.srcmask);
657 
658 		if (!(hinfo->cfg.mode &
659 		      (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
660 			return 0;
661 		nexthdr = ip_hdr(skb)->protocol;
662 		break;
663 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
664 	case NFPROTO_IPV6:
665 	{
666 		__be16 frag_off;
667 
668 		if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) {
669 			memcpy(&dst->ip6.dst, &ipv6_hdr(skb)->daddr,
670 			       sizeof(dst->ip6.dst));
671 			hashlimit_ipv6_mask(dst->ip6.dst, hinfo->cfg.dstmask);
672 		}
673 		if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) {
674 			memcpy(&dst->ip6.src, &ipv6_hdr(skb)->saddr,
675 			       sizeof(dst->ip6.src));
676 			hashlimit_ipv6_mask(dst->ip6.src, hinfo->cfg.srcmask);
677 		}
678 
679 		if (!(hinfo->cfg.mode &
680 		      (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
681 			return 0;
682 		nexthdr = ipv6_hdr(skb)->nexthdr;
683 		protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, &frag_off);
684 		if ((int)protoff < 0)
685 			return -1;
686 		break;
687 	}
688 #endif
689 	default:
690 		BUG();
691 		return 0;
692 	}
693 
694 	poff = proto_ports_offset(nexthdr);
695 	if (poff >= 0) {
696 		ports = skb_header_pointer(skb, protoff + poff, sizeof(_ports),
697 					   &_ports);
698 	} else {
699 		_ports[0] = _ports[1] = 0;
700 		ports = _ports;
701 	}
702 	if (!ports)
703 		return -1;
704 	if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT)
705 		dst->src_port = ports[0];
706 	if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT)
707 		dst->dst_port = ports[1];
708 	return 0;
709 }
710 
711 static u32 hashlimit_byte_cost(unsigned int len, struct dsthash_ent *dh)
712 {
713 	u64 tmp = xt_hashlimit_len_to_chunks(len);
714 	tmp = tmp * dh->rateinfo.cost;
715 
716 	if (unlikely(tmp > CREDITS_PER_JIFFY_BYTES * HZ))
717 		tmp = CREDITS_PER_JIFFY_BYTES * HZ;
718 
719 	if (dh->rateinfo.credit < tmp && dh->rateinfo.credit_cap) {
720 		dh->rateinfo.credit_cap--;
721 		dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
722 	}
723 	return (u32) tmp;
724 }
725 
726 static bool
727 hashlimit_mt_common(const struct sk_buff *skb, struct xt_action_param *par,
728 		    struct xt_hashlimit_htable *hinfo,
729 		    const struct hashlimit_cfg3 *cfg, int revision)
730 {
731 	unsigned long now = jiffies;
732 	struct dsthash_ent *dh;
733 	struct dsthash_dst dst;
734 	bool race = false;
735 	u64 cost;
736 
737 	if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0)
738 		goto hotdrop;
739 
740 	local_bh_disable();
741 	dh = dsthash_find(hinfo, &dst);
742 	if (dh == NULL) {
743 		dh = dsthash_alloc_init(hinfo, &dst, &race);
744 		if (dh == NULL) {
745 			local_bh_enable();
746 			goto hotdrop;
747 		} else if (race) {
748 			/* Already got an entry, update expiration timeout */
749 			dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
750 			rateinfo_recalc(dh, now, hinfo->cfg.mode, revision);
751 		} else {
752 			dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
753 			rateinfo_init(dh, hinfo, revision);
754 		}
755 	} else {
756 		/* update expiration timeout */
757 		dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
758 		rateinfo_recalc(dh, now, hinfo->cfg.mode, revision);
759 	}
760 
761 	if (cfg->mode & XT_HASHLIMIT_RATE_MATCH) {
762 		cost = (cfg->mode & XT_HASHLIMIT_BYTES) ? skb->len : 1;
763 		dh->rateinfo.current_rate += cost;
764 
765 		if (!dh->rateinfo.prev_window &&
766 		    (dh->rateinfo.current_rate <= dh->rateinfo.burst)) {
767 			spin_unlock(&dh->lock);
768 			local_bh_enable();
769 			return !(cfg->mode & XT_HASHLIMIT_INVERT);
770 		} else {
771 			goto overlimit;
772 		}
773 	}
774 
775 	if (cfg->mode & XT_HASHLIMIT_BYTES)
776 		cost = hashlimit_byte_cost(skb->len, dh);
777 	else
778 		cost = dh->rateinfo.cost;
779 
780 	if (dh->rateinfo.credit >= cost) {
781 		/* below the limit */
782 		dh->rateinfo.credit -= cost;
783 		spin_unlock(&dh->lock);
784 		local_bh_enable();
785 		return !(cfg->mode & XT_HASHLIMIT_INVERT);
786 	}
787 
788 overlimit:
789 	spin_unlock(&dh->lock);
790 	local_bh_enable();
791 	/* default match is underlimit - so over the limit, we need to invert */
792 	return cfg->mode & XT_HASHLIMIT_INVERT;
793 
794  hotdrop:
795 	par->hotdrop = true;
796 	return false;
797 }
798 
799 static bool
800 hashlimit_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
801 {
802 	const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
803 	struct xt_hashlimit_htable *hinfo = info->hinfo;
804 	struct hashlimit_cfg3 cfg = {};
805 	int ret;
806 
807 	ret = cfg_copy(&cfg, (void *)&info->cfg, 1);
808 	if (ret)
809 		return ret;
810 
811 	return hashlimit_mt_common(skb, par, hinfo, &cfg, 1);
812 }
813 
814 static bool
815 hashlimit_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
816 {
817 	const struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
818 	struct xt_hashlimit_htable *hinfo = info->hinfo;
819 	struct hashlimit_cfg3 cfg = {};
820 	int ret;
821 
822 	ret = cfg_copy(&cfg, (void *)&info->cfg, 2);
823 	if (ret)
824 		return ret;
825 
826 	return hashlimit_mt_common(skb, par, hinfo, &cfg, 2);
827 }
828 
829 static bool
830 hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par)
831 {
832 	const struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
833 	struct xt_hashlimit_htable *hinfo = info->hinfo;
834 
835 	return hashlimit_mt_common(skb, par, hinfo, &info->cfg, 3);
836 }
837 
838 #define HASHLIMIT_MAX_SIZE 1048576
839 
840 static int hashlimit_mt_check_common(const struct xt_mtchk_param *par,
841 				     struct xt_hashlimit_htable **hinfo,
842 				     struct hashlimit_cfg3 *cfg,
843 				     const char *name, int revision)
844 {
845 	struct net *net = par->net;
846 	int ret;
847 
848 	if (cfg->gc_interval == 0 || cfg->expire == 0)
849 		return -EINVAL;
850 	if (cfg->size > HASHLIMIT_MAX_SIZE) {
851 		cfg->size = HASHLIMIT_MAX_SIZE;
852 		pr_info_ratelimited("size too large, truncated to %u\n", cfg->size);
853 	}
854 	if (cfg->max > HASHLIMIT_MAX_SIZE) {
855 		cfg->max = HASHLIMIT_MAX_SIZE;
856 		pr_info_ratelimited("max too large, truncated to %u\n", cfg->max);
857 	}
858 	if (par->family == NFPROTO_IPV4) {
859 		if (cfg->srcmask > 32 || cfg->dstmask > 32)
860 			return -EINVAL;
861 	} else {
862 		if (cfg->srcmask > 128 || cfg->dstmask > 128)
863 			return -EINVAL;
864 	}
865 
866 	if (cfg->mode & ~XT_HASHLIMIT_ALL) {
867 		pr_info_ratelimited("Unknown mode mask %X, kernel too old?\n",
868 				    cfg->mode);
869 		return -EINVAL;
870 	}
871 
872 	/* Check for overflow. */
873 	if (revision >= 3 && cfg->mode & XT_HASHLIMIT_RATE_MATCH) {
874 		if (cfg->avg == 0 || cfg->avg > U32_MAX) {
875 			pr_info_ratelimited("invalid rate\n");
876 			return -ERANGE;
877 		}
878 
879 		if (cfg->interval == 0) {
880 			pr_info_ratelimited("invalid interval\n");
881 			return -EINVAL;
882 		}
883 	} else if (cfg->mode & XT_HASHLIMIT_BYTES) {
884 		if (user2credits_byte(cfg->avg) == 0) {
885 			pr_info_ratelimited("overflow, rate too high: %llu\n",
886 					    cfg->avg);
887 			return -EINVAL;
888 		}
889 	} else if (cfg->burst == 0 ||
890 		   user2credits(cfg->avg * cfg->burst, revision) <
891 		   user2credits(cfg->avg, revision)) {
892 		pr_info_ratelimited("overflow, try lower: %llu/%llu\n",
893 				    cfg->avg, cfg->burst);
894 		return -ERANGE;
895 	}
896 
897 	mutex_lock(&hashlimit_mutex);
898 	*hinfo = htable_find_get(net, name, par->family);
899 	if (*hinfo == NULL) {
900 		ret = htable_create(net, cfg, name, par->family,
901 				    hinfo, revision);
902 		if (ret < 0) {
903 			mutex_unlock(&hashlimit_mutex);
904 			return ret;
905 		}
906 	}
907 	mutex_unlock(&hashlimit_mutex);
908 
909 	return 0;
910 }
911 
912 static int hashlimit_mt_check_v1(const struct xt_mtchk_param *par)
913 {
914 	struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
915 	struct hashlimit_cfg3 cfg = {};
916 	int ret;
917 
918 	ret = xt_check_proc_name(info->name, sizeof(info->name));
919 	if (ret)
920 		return ret;
921 
922 	ret = cfg_copy(&cfg, (void *)&info->cfg, 1);
923 	if (ret)
924 		return ret;
925 
926 	return hashlimit_mt_check_common(par, &info->hinfo,
927 					 &cfg, info->name, 1);
928 }
929 
930 static int hashlimit_mt_check_v2(const struct xt_mtchk_param *par)
931 {
932 	struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
933 	struct hashlimit_cfg3 cfg = {};
934 	int ret;
935 
936 	ret = xt_check_proc_name(info->name, sizeof(info->name));
937 	if (ret)
938 		return ret;
939 
940 	ret = cfg_copy(&cfg, (void *)&info->cfg, 2);
941 	if (ret)
942 		return ret;
943 
944 	return hashlimit_mt_check_common(par, &info->hinfo,
945 					 &cfg, info->name, 2);
946 }
947 
948 static int hashlimit_mt_check(const struct xt_mtchk_param *par)
949 {
950 	struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
951 	int ret;
952 
953 	ret = xt_check_proc_name(info->name, sizeof(info->name));
954 	if (ret)
955 		return ret;
956 
957 	return hashlimit_mt_check_common(par, &info->hinfo, &info->cfg,
958 					 info->name, 3);
959 }
960 
961 static void hashlimit_mt_destroy_v2(const struct xt_mtdtor_param *par)
962 {
963 	const struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
964 
965 	htable_put(info->hinfo);
966 }
967 
968 static void hashlimit_mt_destroy_v1(const struct xt_mtdtor_param *par)
969 {
970 	const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
971 
972 	htable_put(info->hinfo);
973 }
974 
975 static void hashlimit_mt_destroy(const struct xt_mtdtor_param *par)
976 {
977 	const struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
978 
979 	htable_put(info->hinfo);
980 }
981 
982 static struct xt_match hashlimit_mt_reg[] __read_mostly = {
983 	{
984 		.name           = "hashlimit",
985 		.revision       = 1,
986 		.family         = NFPROTO_IPV4,
987 		.match          = hashlimit_mt_v1,
988 		.matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
989 		.usersize	= offsetof(struct xt_hashlimit_mtinfo1, hinfo),
990 		.checkentry     = hashlimit_mt_check_v1,
991 		.destroy        = hashlimit_mt_destroy_v1,
992 		.me             = THIS_MODULE,
993 	},
994 	{
995 		.name           = "hashlimit",
996 		.revision       = 2,
997 		.family         = NFPROTO_IPV4,
998 		.match          = hashlimit_mt_v2,
999 		.matchsize      = sizeof(struct xt_hashlimit_mtinfo2),
1000 		.usersize	= offsetof(struct xt_hashlimit_mtinfo2, hinfo),
1001 		.checkentry     = hashlimit_mt_check_v2,
1002 		.destroy        = hashlimit_mt_destroy_v2,
1003 		.me             = THIS_MODULE,
1004 	},
1005 	{
1006 		.name           = "hashlimit",
1007 		.revision       = 3,
1008 		.family         = NFPROTO_IPV4,
1009 		.match          = hashlimit_mt,
1010 		.matchsize      = sizeof(struct xt_hashlimit_mtinfo3),
1011 		.usersize	= offsetof(struct xt_hashlimit_mtinfo3, hinfo),
1012 		.checkentry     = hashlimit_mt_check,
1013 		.destroy        = hashlimit_mt_destroy,
1014 		.me             = THIS_MODULE,
1015 	},
1016 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1017 	{
1018 		.name           = "hashlimit",
1019 		.revision       = 1,
1020 		.family         = NFPROTO_IPV6,
1021 		.match          = hashlimit_mt_v1,
1022 		.matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
1023 		.usersize	= offsetof(struct xt_hashlimit_mtinfo1, hinfo),
1024 		.checkentry     = hashlimit_mt_check_v1,
1025 		.destroy        = hashlimit_mt_destroy_v1,
1026 		.me             = THIS_MODULE,
1027 	},
1028 	{
1029 		.name           = "hashlimit",
1030 		.revision       = 2,
1031 		.family         = NFPROTO_IPV6,
1032 		.match          = hashlimit_mt_v2,
1033 		.matchsize      = sizeof(struct xt_hashlimit_mtinfo2),
1034 		.usersize	= offsetof(struct xt_hashlimit_mtinfo2, hinfo),
1035 		.checkentry     = hashlimit_mt_check_v2,
1036 		.destroy        = hashlimit_mt_destroy_v2,
1037 		.me             = THIS_MODULE,
1038 	},
1039 	{
1040 		.name           = "hashlimit",
1041 		.revision       = 3,
1042 		.family         = NFPROTO_IPV6,
1043 		.match          = hashlimit_mt,
1044 		.matchsize      = sizeof(struct xt_hashlimit_mtinfo3),
1045 		.usersize	= offsetof(struct xt_hashlimit_mtinfo3, hinfo),
1046 		.checkentry     = hashlimit_mt_check,
1047 		.destroy        = hashlimit_mt_destroy,
1048 		.me             = THIS_MODULE,
1049 	},
1050 #endif
1051 };
1052 
1053 /* PROC stuff */
1054 static void *dl_seq_start(struct seq_file *s, loff_t *pos)
1055 	__acquires(htable->lock)
1056 {
1057 	struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file));
1058 	unsigned int *bucket;
1059 
1060 	spin_lock_bh(&htable->lock);
1061 	if (*pos >= htable->cfg.size)
1062 		return NULL;
1063 
1064 	bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
1065 	if (!bucket)
1066 		return ERR_PTR(-ENOMEM);
1067 
1068 	*bucket = *pos;
1069 	return bucket;
1070 }
1071 
1072 static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
1073 {
1074 	struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file));
1075 	unsigned int *bucket = v;
1076 
1077 	*pos = ++(*bucket);
1078 	if (*pos >= htable->cfg.size) {
1079 		kfree(v);
1080 		return NULL;
1081 	}
1082 	return bucket;
1083 }
1084 
1085 static void dl_seq_stop(struct seq_file *s, void *v)
1086 	__releases(htable->lock)
1087 {
1088 	struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file));
1089 	unsigned int *bucket = v;
1090 
1091 	if (!IS_ERR(bucket))
1092 		kfree(bucket);
1093 	spin_unlock_bh(&htable->lock);
1094 }
1095 
1096 static void dl_seq_print(struct dsthash_ent *ent, u_int8_t family,
1097 			 struct seq_file *s)
1098 {
1099 	switch (family) {
1100 	case NFPROTO_IPV4:
1101 		seq_printf(s, "%ld %pI4:%u->%pI4:%u %llu %llu %llu\n",
1102 			   (long)(ent->expires - jiffies)/HZ,
1103 			   &ent->dst.ip.src,
1104 			   ntohs(ent->dst.src_port),
1105 			   &ent->dst.ip.dst,
1106 			   ntohs(ent->dst.dst_port),
1107 			   ent->rateinfo.credit, ent->rateinfo.credit_cap,
1108 			   ent->rateinfo.cost);
1109 		break;
1110 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1111 	case NFPROTO_IPV6:
1112 		seq_printf(s, "%ld %pI6:%u->%pI6:%u %llu %llu %llu\n",
1113 			   (long)(ent->expires - jiffies)/HZ,
1114 			   &ent->dst.ip6.src,
1115 			   ntohs(ent->dst.src_port),
1116 			   &ent->dst.ip6.dst,
1117 			   ntohs(ent->dst.dst_port),
1118 			   ent->rateinfo.credit, ent->rateinfo.credit_cap,
1119 			   ent->rateinfo.cost);
1120 		break;
1121 #endif
1122 	default:
1123 		BUG();
1124 	}
1125 }
1126 
1127 static int dl_seq_real_show_v2(struct dsthash_ent *ent, u_int8_t family,
1128 			       struct seq_file *s)
1129 {
1130 	struct xt_hashlimit_htable *ht = pde_data(file_inode(s->file));
1131 
1132 	spin_lock(&ent->lock);
1133 	/* recalculate to show accurate numbers */
1134 	rateinfo_recalc(ent, jiffies, ht->cfg.mode, 2);
1135 
1136 	dl_seq_print(ent, family, s);
1137 
1138 	spin_unlock(&ent->lock);
1139 	return seq_has_overflowed(s);
1140 }
1141 
1142 static int dl_seq_real_show_v1(struct dsthash_ent *ent, u_int8_t family,
1143 			       struct seq_file *s)
1144 {
1145 	struct xt_hashlimit_htable *ht = pde_data(file_inode(s->file));
1146 
1147 	spin_lock(&ent->lock);
1148 	/* recalculate to show accurate numbers */
1149 	rateinfo_recalc(ent, jiffies, ht->cfg.mode, 1);
1150 
1151 	dl_seq_print(ent, family, s);
1152 
1153 	spin_unlock(&ent->lock);
1154 	return seq_has_overflowed(s);
1155 }
1156 
1157 static int dl_seq_real_show(struct dsthash_ent *ent, u_int8_t family,
1158 			    struct seq_file *s)
1159 {
1160 	struct xt_hashlimit_htable *ht = pde_data(file_inode(s->file));
1161 
1162 	spin_lock(&ent->lock);
1163 	/* recalculate to show accurate numbers */
1164 	rateinfo_recalc(ent, jiffies, ht->cfg.mode, 3);
1165 
1166 	dl_seq_print(ent, family, s);
1167 
1168 	spin_unlock(&ent->lock);
1169 	return seq_has_overflowed(s);
1170 }
1171 
1172 static int dl_seq_show_v2(struct seq_file *s, void *v)
1173 {
1174 	struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file));
1175 	unsigned int *bucket = (unsigned int *)v;
1176 	struct dsthash_ent *ent;
1177 
1178 	if (!hlist_empty(&htable->hash[*bucket])) {
1179 		hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1180 			if (dl_seq_real_show_v2(ent, htable->family, s))
1181 				return -1;
1182 	}
1183 	return 0;
1184 }
1185 
1186 static int dl_seq_show_v1(struct seq_file *s, void *v)
1187 {
1188 	struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file));
1189 	unsigned int *bucket = v;
1190 	struct dsthash_ent *ent;
1191 
1192 	if (!hlist_empty(&htable->hash[*bucket])) {
1193 		hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1194 			if (dl_seq_real_show_v1(ent, htable->family, s))
1195 				return -1;
1196 	}
1197 	return 0;
1198 }
1199 
1200 static int dl_seq_show(struct seq_file *s, void *v)
1201 {
1202 	struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file));
1203 	unsigned int *bucket = v;
1204 	struct dsthash_ent *ent;
1205 
1206 	if (!hlist_empty(&htable->hash[*bucket])) {
1207 		hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1208 			if (dl_seq_real_show(ent, htable->family, s))
1209 				return -1;
1210 	}
1211 	return 0;
1212 }
1213 
1214 static const struct seq_operations dl_seq_ops_v1 = {
1215 	.start = dl_seq_start,
1216 	.next  = dl_seq_next,
1217 	.stop  = dl_seq_stop,
1218 	.show  = dl_seq_show_v1
1219 };
1220 
1221 static const struct seq_operations dl_seq_ops_v2 = {
1222 	.start = dl_seq_start,
1223 	.next  = dl_seq_next,
1224 	.stop  = dl_seq_stop,
1225 	.show  = dl_seq_show_v2
1226 };
1227 
1228 static const struct seq_operations dl_seq_ops = {
1229 	.start = dl_seq_start,
1230 	.next  = dl_seq_next,
1231 	.stop  = dl_seq_stop,
1232 	.show  = dl_seq_show
1233 };
1234 
1235 static int __net_init hashlimit_proc_net_init(struct net *net)
1236 {
1237 	struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1238 
1239 	hashlimit_net->ipt_hashlimit = proc_mkdir("ipt_hashlimit", net->proc_net);
1240 	if (!hashlimit_net->ipt_hashlimit)
1241 		return -ENOMEM;
1242 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1243 	hashlimit_net->ip6t_hashlimit = proc_mkdir("ip6t_hashlimit", net->proc_net);
1244 	if (!hashlimit_net->ip6t_hashlimit) {
1245 		remove_proc_entry("ipt_hashlimit", net->proc_net);
1246 		return -ENOMEM;
1247 	}
1248 #endif
1249 	return 0;
1250 }
1251 
1252 static void __net_exit hashlimit_proc_net_exit(struct net *net)
1253 {
1254 	struct xt_hashlimit_htable *hinfo;
1255 	struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1256 
1257 	/* hashlimit_net_exit() is called before hashlimit_mt_destroy().
1258 	 * Make sure that the parent ipt_hashlimit and ip6t_hashlimit proc
1259 	 * entries is empty before trying to remove it.
1260 	 */
1261 	mutex_lock(&hashlimit_mutex);
1262 	hlist_for_each_entry(hinfo, &hashlimit_net->htables, node)
1263 		htable_remove_proc_entry(hinfo);
1264 	hashlimit_net->ipt_hashlimit = NULL;
1265 	hashlimit_net->ip6t_hashlimit = NULL;
1266 	mutex_unlock(&hashlimit_mutex);
1267 
1268 	remove_proc_entry("ipt_hashlimit", net->proc_net);
1269 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1270 	remove_proc_entry("ip6t_hashlimit", net->proc_net);
1271 #endif
1272 }
1273 
1274 static int __net_init hashlimit_net_init(struct net *net)
1275 {
1276 	struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1277 
1278 	INIT_HLIST_HEAD(&hashlimit_net->htables);
1279 	return hashlimit_proc_net_init(net);
1280 }
1281 
1282 static void __net_exit hashlimit_net_exit(struct net *net)
1283 {
1284 	hashlimit_proc_net_exit(net);
1285 }
1286 
1287 static struct pernet_operations hashlimit_net_ops = {
1288 	.init	= hashlimit_net_init,
1289 	.exit	= hashlimit_net_exit,
1290 	.id	= &hashlimit_net_id,
1291 	.size	= sizeof(struct hashlimit_net),
1292 };
1293 
1294 static int __init hashlimit_mt_init(void)
1295 {
1296 	int err;
1297 
1298 	err = register_pernet_subsys(&hashlimit_net_ops);
1299 	if (err < 0)
1300 		return err;
1301 	err = xt_register_matches(hashlimit_mt_reg,
1302 	      ARRAY_SIZE(hashlimit_mt_reg));
1303 	if (err < 0)
1304 		goto err1;
1305 
1306 	err = -ENOMEM;
1307 	hashlimit_cachep = kmem_cache_create("xt_hashlimit",
1308 					    sizeof(struct dsthash_ent), 0, 0,
1309 					    NULL);
1310 	if (!hashlimit_cachep) {
1311 		pr_warn("unable to create slab cache\n");
1312 		goto err2;
1313 	}
1314 	return 0;
1315 
1316 err2:
1317 	xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
1318 err1:
1319 	unregister_pernet_subsys(&hashlimit_net_ops);
1320 	return err;
1321 
1322 }
1323 
1324 static void __exit hashlimit_mt_exit(void)
1325 {
1326 	xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
1327 	unregister_pernet_subsys(&hashlimit_net_ops);
1328 
1329 	rcu_barrier();
1330 	kmem_cache_destroy(hashlimit_cachep);
1331 }
1332 
1333 module_init(hashlimit_mt_init);
1334 module_exit(hashlimit_mt_exit);
1335