xref: /openbmc/linux/net/netfilter/xt_hashlimit.c (revision 359745d7)
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/vmalloc.h>
19 #include <linux/proc_fs.h>
20 #include <linux/seq_file.h>
21 #include <linux/list.h>
22 #include <linux/skbuff.h>
23 #include <linux/mm.h>
24 #include <linux/in.h>
25 #include <linux/ip.h>
26 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
27 #include <linux/ipv6.h>
28 #include <net/ipv6.h>
29 #endif
30 
31 #include <net/net_namespace.h>
32 #include <net/netns/generic.h>
33 
34 #include <linux/netfilter/x_tables.h>
35 #include <linux/netfilter_ipv4/ip_tables.h>
36 #include <linux/netfilter_ipv6/ip6_tables.h>
37 #include <linux/mutex.h>
38 #include <linux/kernel.h>
39 #include <linux/refcount.h>
40 #include <uapi/linux/netfilter/xt_hashlimit.h>
41 
42 #define XT_HASHLIMIT_ALL (XT_HASHLIMIT_HASH_DIP | XT_HASHLIMIT_HASH_DPT | \
43 			  XT_HASHLIMIT_HASH_SIP | XT_HASHLIMIT_HASH_SPT | \
44 			  XT_HASHLIMIT_INVERT | XT_HASHLIMIT_BYTES |\
45 			  XT_HASHLIMIT_RATE_MATCH)
46 
47 MODULE_LICENSE("GPL");
48 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
49 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
50 MODULE_DESCRIPTION("Xtables: per hash-bucket rate-limit match");
51 MODULE_ALIAS("ipt_hashlimit");
52 MODULE_ALIAS("ip6t_hashlimit");
53 
54 struct hashlimit_net {
55 	struct hlist_head	htables;
56 	struct proc_dir_entry	*ipt_hashlimit;
57 	struct proc_dir_entry	*ip6t_hashlimit;
58 };
59 
60 static unsigned int hashlimit_net_id;
hashlimit_pernet(struct net * net)61 static inline struct hashlimit_net *hashlimit_pernet(struct net *net)
62 {
63 	return net_generic(net, hashlimit_net_id);
64 }
65 
66 /* need to declare this at the top */
67 static const struct seq_operations dl_seq_ops_v2;
68 static const struct seq_operations dl_seq_ops_v1;
69 static const struct seq_operations dl_seq_ops;
70 
71 /* hash table crap */
72 struct dsthash_dst {
73 	union {
74 		struct {
75 			__be32 src;
76 			__be32 dst;
77 		} ip;
78 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
79 		struct {
80 			__be32 src[4];
81 			__be32 dst[4];
82 		} ip6;
83 #endif
84 	};
85 	__be16 src_port;
86 	__be16 dst_port;
87 };
88 
89 struct dsthash_ent {
90 	/* static / read-only parts in the beginning */
91 	struct hlist_node node;
92 	struct dsthash_dst dst;
93 
94 	/* modified structure members in the end */
95 	spinlock_t lock;
96 	unsigned long expires;		/* precalculated expiry time */
97 	struct {
98 		unsigned long prev;	/* last modification */
99 		union {
100 			struct {
101 				u_int64_t credit;
102 				u_int64_t credit_cap;
103 				u_int64_t cost;
104 			};
105 			struct {
106 				u_int32_t interval, prev_window;
107 				u_int64_t current_rate;
108 				u_int64_t rate;
109 				int64_t burst;
110 			};
111 		};
112 	} rateinfo;
113 	struct rcu_head rcu;
114 };
115 
116 struct xt_hashlimit_htable {
117 	struct hlist_node node;		/* global list of all htables */
118 	refcount_t use;
119 	u_int8_t family;
120 	bool rnd_initialized;
121 
122 	struct hashlimit_cfg3 cfg;	/* config */
123 
124 	/* used internally */
125 	spinlock_t lock;		/* lock for list_head */
126 	u_int32_t rnd;			/* random seed for hash */
127 	unsigned int count;		/* number entries in table */
128 	struct delayed_work gc_work;
129 
130 	/* seq_file stuff */
131 	struct proc_dir_entry *pde;
132 	const char *name;
133 	struct net *net;
134 
135 	struct hlist_head hash[];	/* hashtable itself */
136 };
137 
138 static int
cfg_copy(struct hashlimit_cfg3 * to,const void * from,int revision)139 cfg_copy(struct hashlimit_cfg3 *to, const void *from, int revision)
140 {
141 	if (revision == 1) {
142 		struct hashlimit_cfg1 *cfg = (struct hashlimit_cfg1 *)from;
143 
144 		to->mode = cfg->mode;
145 		to->avg = cfg->avg;
146 		to->burst = cfg->burst;
147 		to->size = cfg->size;
148 		to->max = cfg->max;
149 		to->gc_interval = cfg->gc_interval;
150 		to->expire = cfg->expire;
151 		to->srcmask = cfg->srcmask;
152 		to->dstmask = cfg->dstmask;
153 	} else if (revision == 2) {
154 		struct hashlimit_cfg2 *cfg = (struct hashlimit_cfg2 *)from;
155 
156 		to->mode = cfg->mode;
157 		to->avg = cfg->avg;
158 		to->burst = cfg->burst;
159 		to->size = cfg->size;
160 		to->max = cfg->max;
161 		to->gc_interval = cfg->gc_interval;
162 		to->expire = cfg->expire;
163 		to->srcmask = cfg->srcmask;
164 		to->dstmask = cfg->dstmask;
165 	} else if (revision == 3) {
166 		memcpy(to, from, sizeof(struct hashlimit_cfg3));
167 	} else {
168 		return -EINVAL;
169 	}
170 
171 	return 0;
172 }
173 
174 static DEFINE_MUTEX(hashlimit_mutex);	/* protects htables list */
175 static struct kmem_cache *hashlimit_cachep __read_mostly;
176 
dst_cmp(const struct dsthash_ent * ent,const struct dsthash_dst * b)177 static inline bool dst_cmp(const struct dsthash_ent *ent,
178 			   const struct dsthash_dst *b)
179 {
180 	return !memcmp(&ent->dst, b, sizeof(ent->dst));
181 }
182 
183 static u_int32_t
hash_dst(const struct xt_hashlimit_htable * ht,const struct dsthash_dst * dst)184 hash_dst(const struct xt_hashlimit_htable *ht, const struct dsthash_dst *dst)
185 {
186 	u_int32_t hash = jhash2((const u32 *)dst,
187 				sizeof(*dst)/sizeof(u32),
188 				ht->rnd);
189 	/*
190 	 * Instead of returning hash % ht->cfg.size (implying a divide)
191 	 * we return the high 32 bits of the (hash * ht->cfg.size) that will
192 	 * give results between [0 and cfg.size-1] and same hash distribution,
193 	 * but using a multiply, less expensive than a divide
194 	 */
195 	return reciprocal_scale(hash, ht->cfg.size);
196 }
197 
198 static struct dsthash_ent *
dsthash_find(const struct xt_hashlimit_htable * ht,const struct dsthash_dst * dst)199 dsthash_find(const struct xt_hashlimit_htable *ht,
200 	     const struct dsthash_dst *dst)
201 {
202 	struct dsthash_ent *ent;
203 	u_int32_t hash = hash_dst(ht, dst);
204 
205 	if (!hlist_empty(&ht->hash[hash])) {
206 		hlist_for_each_entry_rcu(ent, &ht->hash[hash], node)
207 			if (dst_cmp(ent, dst)) {
208 				spin_lock(&ent->lock);
209 				return ent;
210 			}
211 	}
212 	return NULL;
213 }
214 
215 /* allocate dsthash_ent, initialize dst, put in htable and lock it */
216 static struct dsthash_ent *
dsthash_alloc_init(struct xt_hashlimit_htable * ht,const struct dsthash_dst * dst,bool * race)217 dsthash_alloc_init(struct xt_hashlimit_htable *ht,
218 		   const struct dsthash_dst *dst, bool *race)
219 {
220 	struct dsthash_ent *ent;
221 
222 	spin_lock(&ht->lock);
223 
224 	/* Two or more packets may race to create the same entry in the
225 	 * hashtable, double check if this packet lost race.
226 	 */
227 	ent = dsthash_find(ht, dst);
228 	if (ent != NULL) {
229 		spin_unlock(&ht->lock);
230 		*race = true;
231 		return ent;
232 	}
233 
234 	/* initialize hash with random val at the time we allocate
235 	 * the first hashtable entry */
236 	if (unlikely(!ht->rnd_initialized)) {
237 		get_random_bytes(&ht->rnd, sizeof(ht->rnd));
238 		ht->rnd_initialized = true;
239 	}
240 
241 	if (ht->cfg.max && ht->count >= ht->cfg.max) {
242 		/* FIXME: do something. question is what.. */
243 		net_err_ratelimited("max count of %u reached\n", ht->cfg.max);
244 		ent = NULL;
245 	} else
246 		ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
247 	if (ent) {
248 		memcpy(&ent->dst, dst, sizeof(ent->dst));
249 		spin_lock_init(&ent->lock);
250 
251 		spin_lock(&ent->lock);
252 		hlist_add_head_rcu(&ent->node, &ht->hash[hash_dst(ht, dst)]);
253 		ht->count++;
254 	}
255 	spin_unlock(&ht->lock);
256 	return ent;
257 }
258 
dsthash_free_rcu(struct rcu_head * head)259 static void dsthash_free_rcu(struct rcu_head *head)
260 {
261 	struct dsthash_ent *ent = container_of(head, struct dsthash_ent, rcu);
262 
263 	kmem_cache_free(hashlimit_cachep, ent);
264 }
265 
266 static inline void
dsthash_free(struct xt_hashlimit_htable * ht,struct dsthash_ent * ent)267 dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent)
268 {
269 	hlist_del_rcu(&ent->node);
270 	call_rcu(&ent->rcu, dsthash_free_rcu);
271 	ht->count--;
272 }
273 static void htable_gc(struct work_struct *work);
274 
htable_create(struct net * net,struct hashlimit_cfg3 * cfg,const char * name,u_int8_t family,struct xt_hashlimit_htable ** out_hinfo,int revision)275 static int htable_create(struct net *net, struct hashlimit_cfg3 *cfg,
276 			 const char *name, u_int8_t family,
277 			 struct xt_hashlimit_htable **out_hinfo,
278 			 int revision)
279 {
280 	struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
281 	struct xt_hashlimit_htable *hinfo;
282 	const struct seq_operations *ops;
283 	unsigned int size, i;
284 	unsigned long nr_pages = totalram_pages();
285 	int ret;
286 
287 	if (cfg->size) {
288 		size = cfg->size;
289 	} else {
290 		size = (nr_pages << PAGE_SHIFT) / 16384 /
291 		       sizeof(struct hlist_head);
292 		if (nr_pages > 1024 * 1024 * 1024 / PAGE_SIZE)
293 			size = 8192;
294 		if (size < 16)
295 			size = 16;
296 	}
297 	/* FIXME: don't use vmalloc() here or anywhere else -HW */
298 	hinfo = vmalloc(struct_size(hinfo, hash, size));
299 	if (hinfo == NULL)
300 		return -ENOMEM;
301 	*out_hinfo = hinfo;
302 
303 	/* copy match config into hashtable config */
304 	ret = cfg_copy(&hinfo->cfg, (void *)cfg, 3);
305 	if (ret) {
306 		vfree(hinfo);
307 		return ret;
308 	}
309 
310 	hinfo->cfg.size = size;
311 	if (hinfo->cfg.max == 0)
312 		hinfo->cfg.max = 8 * hinfo->cfg.size;
313 	else if (hinfo->cfg.max < hinfo->cfg.size)
314 		hinfo->cfg.max = hinfo->cfg.size;
315 
316 	for (i = 0; i < hinfo->cfg.size; i++)
317 		INIT_HLIST_HEAD(&hinfo->hash[i]);
318 
319 	refcount_set(&hinfo->use, 1);
320 	hinfo->count = 0;
321 	hinfo->family = family;
322 	hinfo->rnd_initialized = false;
323 	hinfo->name = kstrdup(name, GFP_KERNEL);
324 	if (!hinfo->name) {
325 		vfree(hinfo);
326 		return -ENOMEM;
327 	}
328 	spin_lock_init(&hinfo->lock);
329 
330 	switch (revision) {
331 	case 1:
332 		ops = &dl_seq_ops_v1;
333 		break;
334 	case 2:
335 		ops = &dl_seq_ops_v2;
336 		break;
337 	default:
338 		ops = &dl_seq_ops;
339 	}
340 
341 	hinfo->pde = proc_create_seq_data(name, 0,
342 		(family == NFPROTO_IPV4) ?
343 		hashlimit_net->ipt_hashlimit : hashlimit_net->ip6t_hashlimit,
344 		ops, hinfo);
345 	if (hinfo->pde == NULL) {
346 		kfree(hinfo->name);
347 		vfree(hinfo);
348 		return -ENOMEM;
349 	}
350 	hinfo->net = net;
351 
352 	INIT_DEFERRABLE_WORK(&hinfo->gc_work, htable_gc);
353 	queue_delayed_work(system_power_efficient_wq, &hinfo->gc_work,
354 			   msecs_to_jiffies(hinfo->cfg.gc_interval));
355 
356 	hlist_add_head(&hinfo->node, &hashlimit_net->htables);
357 
358 	return 0;
359 }
360 
htable_selective_cleanup(struct xt_hashlimit_htable * ht,bool select_all)361 static void htable_selective_cleanup(struct xt_hashlimit_htable *ht, bool select_all)
362 {
363 	unsigned int i;
364 
365 	for (i = 0; i < ht->cfg.size; i++) {
366 		struct dsthash_ent *dh;
367 		struct hlist_node *n;
368 
369 		spin_lock_bh(&ht->lock);
370 		hlist_for_each_entry_safe(dh, n, &ht->hash[i], node) {
371 			if (time_after_eq(jiffies, dh->expires) || select_all)
372 				dsthash_free(ht, dh);
373 		}
374 		spin_unlock_bh(&ht->lock);
375 		cond_resched();
376 	}
377 }
378 
htable_gc(struct work_struct * work)379 static void htable_gc(struct work_struct *work)
380 {
381 	struct xt_hashlimit_htable *ht;
382 
383 	ht = container_of(work, struct xt_hashlimit_htable, gc_work.work);
384 
385 	htable_selective_cleanup(ht, false);
386 
387 	queue_delayed_work(system_power_efficient_wq,
388 			   &ht->gc_work, msecs_to_jiffies(ht->cfg.gc_interval));
389 }
390 
htable_remove_proc_entry(struct xt_hashlimit_htable * hinfo)391 static void htable_remove_proc_entry(struct xt_hashlimit_htable *hinfo)
392 {
393 	struct hashlimit_net *hashlimit_net = hashlimit_pernet(hinfo->net);
394 	struct proc_dir_entry *parent;
395 
396 	if (hinfo->family == NFPROTO_IPV4)
397 		parent = hashlimit_net->ipt_hashlimit;
398 	else
399 		parent = hashlimit_net->ip6t_hashlimit;
400 
401 	if (parent != NULL)
402 		remove_proc_entry(hinfo->name, parent);
403 }
404 
htable_find_get(struct net * net,const char * name,u_int8_t family)405 static struct xt_hashlimit_htable *htable_find_get(struct net *net,
406 						   const char *name,
407 						   u_int8_t family)
408 {
409 	struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
410 	struct xt_hashlimit_htable *hinfo;
411 
412 	hlist_for_each_entry(hinfo, &hashlimit_net->htables, node) {
413 		if (!strcmp(name, hinfo->name) &&
414 		    hinfo->family == family) {
415 			refcount_inc(&hinfo->use);
416 			return hinfo;
417 		}
418 	}
419 	return NULL;
420 }
421 
htable_put(struct xt_hashlimit_htable * hinfo)422 static void htable_put(struct xt_hashlimit_htable *hinfo)
423 {
424 	if (refcount_dec_and_mutex_lock(&hinfo->use, &hashlimit_mutex)) {
425 		hlist_del(&hinfo->node);
426 		htable_remove_proc_entry(hinfo);
427 		mutex_unlock(&hashlimit_mutex);
428 
429 		cancel_delayed_work_sync(&hinfo->gc_work);
430 		htable_selective_cleanup(hinfo, true);
431 		kfree(hinfo->name);
432 		vfree(hinfo);
433 	}
434 }
435 
436 /* The algorithm used is the Simple Token Bucket Filter (TBF)
437  * see net/sched/sch_tbf.c in the linux source tree
438  */
439 
440 /* Rusty: This is my (non-mathematically-inclined) understanding of
441    this algorithm.  The `average rate' in jiffies becomes your initial
442    amount of credit `credit' and the most credit you can ever have
443    `credit_cap'.  The `peak rate' becomes the cost of passing the
444    test, `cost'.
445 
446    `prev' tracks the last packet hit: you gain one credit per jiffy.
447    If you get credit balance more than this, the extra credit is
448    discarded.  Every time the match passes, you lose `cost' credits;
449    if you don't have that many, the test fails.
450 
451    See Alexey's formal explanation in net/sched/sch_tbf.c.
452 
453    To get the maximum range, we multiply by this factor (ie. you get N
454    credits per jiffy).  We want to allow a rate as low as 1 per day
455    (slowest userspace tool allows), which means
456    CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
457 */
458 #define MAX_CPJ_v1 (0xFFFFFFFF / (HZ*60*60*24))
459 #define MAX_CPJ (0xFFFFFFFFFFFFFFFFULL / (HZ*60*60*24))
460 
461 /* Repeated shift and or gives us all 1s, final shift and add 1 gives
462  * us the power of 2 below the theoretical max, so GCC simply does a
463  * shift. */
464 #define _POW2_BELOW2(x) ((x)|((x)>>1))
465 #define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
466 #define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
467 #define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
468 #define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
469 #define _POW2_BELOW64(x) (_POW2_BELOW32(x)|_POW2_BELOW32((x)>>32))
470 #define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
471 #define POW2_BELOW64(x) ((_POW2_BELOW64(x)>>1) + 1)
472 
473 #define CREDITS_PER_JIFFY POW2_BELOW64(MAX_CPJ)
474 #define CREDITS_PER_JIFFY_v1 POW2_BELOW32(MAX_CPJ_v1)
475 
476 /* in byte mode, the lowest possible rate is one packet/second.
477  * credit_cap is used as a counter that tells us how many times we can
478  * refill the "credits available" counter when it becomes empty.
479  */
480 #define MAX_CPJ_BYTES (0xFFFFFFFF / HZ)
481 #define CREDITS_PER_JIFFY_BYTES POW2_BELOW32(MAX_CPJ_BYTES)
482 
xt_hashlimit_len_to_chunks(u32 len)483 static u32 xt_hashlimit_len_to_chunks(u32 len)
484 {
485 	return (len >> XT_HASHLIMIT_BYTE_SHIFT) + 1;
486 }
487 
488 /* Precision saver. */
user2credits(u64 user,int revision)489 static u64 user2credits(u64 user, int revision)
490 {
491 	u64 scale = (revision == 1) ?
492 		XT_HASHLIMIT_SCALE : XT_HASHLIMIT_SCALE_v2;
493 	u64 cpj = (revision == 1) ?
494 		CREDITS_PER_JIFFY_v1 : CREDITS_PER_JIFFY;
495 
496 	/* Avoid overflow: divide the constant operands first */
497 	if (scale >= HZ * cpj)
498 		return div64_u64(user, div64_u64(scale, HZ * cpj));
499 
500 	return user * div64_u64(HZ * cpj, scale);
501 }
502 
user2credits_byte(u32 user)503 static u32 user2credits_byte(u32 user)
504 {
505 	u64 us = user;
506 	us *= HZ * CREDITS_PER_JIFFY_BYTES;
507 	return (u32) (us >> 32);
508 }
509 
user2rate(u64 user)510 static u64 user2rate(u64 user)
511 {
512 	if (user != 0) {
513 		return div64_u64(XT_HASHLIMIT_SCALE_v2, user);
514 	} else {
515 		pr_info_ratelimited("invalid rate from userspace: %llu\n",
516 				    user);
517 		return 0;
518 	}
519 }
520 
user2rate_bytes(u32 user)521 static u64 user2rate_bytes(u32 user)
522 {
523 	u64 r;
524 
525 	r = user ? U32_MAX / user : U32_MAX;
526 	return (r - 1) << XT_HASHLIMIT_BYTE_SHIFT;
527 }
528 
rateinfo_recalc(struct dsthash_ent * dh,unsigned long now,u32 mode,int revision)529 static void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now,
530 			    u32 mode, int revision)
531 {
532 	unsigned long delta = now - dh->rateinfo.prev;
533 	u64 cap, cpj;
534 
535 	if (delta == 0)
536 		return;
537 
538 	if (revision >= 3 && mode & XT_HASHLIMIT_RATE_MATCH) {
539 		u64 interval = dh->rateinfo.interval * HZ;
540 
541 		if (delta < interval)
542 			return;
543 
544 		dh->rateinfo.prev = now;
545 		dh->rateinfo.prev_window =
546 			((dh->rateinfo.current_rate * interval) >
547 			 (delta * dh->rateinfo.rate));
548 		dh->rateinfo.current_rate = 0;
549 
550 		return;
551 	}
552 
553 	dh->rateinfo.prev = now;
554 
555 	if (mode & XT_HASHLIMIT_BYTES) {
556 		u64 tmp = dh->rateinfo.credit;
557 		dh->rateinfo.credit += CREDITS_PER_JIFFY_BYTES * delta;
558 		cap = CREDITS_PER_JIFFY_BYTES * HZ;
559 		if (tmp >= dh->rateinfo.credit) {/* overflow */
560 			dh->rateinfo.credit = cap;
561 			return;
562 		}
563 	} else {
564 		cpj = (revision == 1) ?
565 			CREDITS_PER_JIFFY_v1 : CREDITS_PER_JIFFY;
566 		dh->rateinfo.credit += delta * cpj;
567 		cap = dh->rateinfo.credit_cap;
568 	}
569 	if (dh->rateinfo.credit > cap)
570 		dh->rateinfo.credit = cap;
571 }
572 
rateinfo_init(struct dsthash_ent * dh,struct xt_hashlimit_htable * hinfo,int revision)573 static void rateinfo_init(struct dsthash_ent *dh,
574 			  struct xt_hashlimit_htable *hinfo, int revision)
575 {
576 	dh->rateinfo.prev = jiffies;
577 	if (revision >= 3 && hinfo->cfg.mode & XT_HASHLIMIT_RATE_MATCH) {
578 		dh->rateinfo.prev_window = 0;
579 		dh->rateinfo.current_rate = 0;
580 		if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) {
581 			dh->rateinfo.rate =
582 				user2rate_bytes((u32)hinfo->cfg.avg);
583 			if (hinfo->cfg.burst)
584 				dh->rateinfo.burst =
585 					hinfo->cfg.burst * dh->rateinfo.rate;
586 			else
587 				dh->rateinfo.burst = dh->rateinfo.rate;
588 		} else {
589 			dh->rateinfo.rate = user2rate(hinfo->cfg.avg);
590 			dh->rateinfo.burst =
591 				hinfo->cfg.burst + dh->rateinfo.rate;
592 		}
593 		dh->rateinfo.interval = hinfo->cfg.interval;
594 	} else if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) {
595 		dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
596 		dh->rateinfo.cost = user2credits_byte(hinfo->cfg.avg);
597 		dh->rateinfo.credit_cap = hinfo->cfg.burst;
598 	} else {
599 		dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
600 						   hinfo->cfg.burst, revision);
601 		dh->rateinfo.cost = user2credits(hinfo->cfg.avg, revision);
602 		dh->rateinfo.credit_cap = dh->rateinfo.credit;
603 	}
604 }
605 
maskl(__be32 a,unsigned int l)606 static inline __be32 maskl(__be32 a, unsigned int l)
607 {
608 	return l ? htonl(ntohl(a) & ~0 << (32 - l)) : 0;
609 }
610 
611 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
hashlimit_ipv6_mask(__be32 * i,unsigned int p)612 static void hashlimit_ipv6_mask(__be32 *i, unsigned int p)
613 {
614 	switch (p) {
615 	case 0 ... 31:
616 		i[0] = maskl(i[0], p);
617 		i[1] = i[2] = i[3] = 0;
618 		break;
619 	case 32 ... 63:
620 		i[1] = maskl(i[1], p - 32);
621 		i[2] = i[3] = 0;
622 		break;
623 	case 64 ... 95:
624 		i[2] = maskl(i[2], p - 64);
625 		i[3] = 0;
626 		break;
627 	case 96 ... 127:
628 		i[3] = maskl(i[3], p - 96);
629 		break;
630 	case 128:
631 		break;
632 	}
633 }
634 #endif
635 
636 static int
hashlimit_init_dst(const struct xt_hashlimit_htable * hinfo,struct dsthash_dst * dst,const struct sk_buff * skb,unsigned int protoff)637 hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
638 		   struct dsthash_dst *dst,
639 		   const struct sk_buff *skb, unsigned int protoff)
640 {
641 	__be16 _ports[2], *ports;
642 	u8 nexthdr;
643 	int poff;
644 
645 	memset(dst, 0, sizeof(*dst));
646 
647 	switch (hinfo->family) {
648 	case NFPROTO_IPV4:
649 		if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
650 			dst->ip.dst = maskl(ip_hdr(skb)->daddr,
651 			              hinfo->cfg.dstmask);
652 		if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
653 			dst->ip.src = maskl(ip_hdr(skb)->saddr,
654 			              hinfo->cfg.srcmask);
655 
656 		if (!(hinfo->cfg.mode &
657 		      (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
658 			return 0;
659 		nexthdr = ip_hdr(skb)->protocol;
660 		break;
661 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
662 	case NFPROTO_IPV6:
663 	{
664 		__be16 frag_off;
665 
666 		if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) {
667 			memcpy(&dst->ip6.dst, &ipv6_hdr(skb)->daddr,
668 			       sizeof(dst->ip6.dst));
669 			hashlimit_ipv6_mask(dst->ip6.dst, hinfo->cfg.dstmask);
670 		}
671 		if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) {
672 			memcpy(&dst->ip6.src, &ipv6_hdr(skb)->saddr,
673 			       sizeof(dst->ip6.src));
674 			hashlimit_ipv6_mask(dst->ip6.src, hinfo->cfg.srcmask);
675 		}
676 
677 		if (!(hinfo->cfg.mode &
678 		      (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
679 			return 0;
680 		nexthdr = ipv6_hdr(skb)->nexthdr;
681 		protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, &frag_off);
682 		if ((int)protoff < 0)
683 			return -1;
684 		break;
685 	}
686 #endif
687 	default:
688 		BUG();
689 		return 0;
690 	}
691 
692 	poff = proto_ports_offset(nexthdr);
693 	if (poff >= 0) {
694 		ports = skb_header_pointer(skb, protoff + poff, sizeof(_ports),
695 					   &_ports);
696 	} else {
697 		_ports[0] = _ports[1] = 0;
698 		ports = _ports;
699 	}
700 	if (!ports)
701 		return -1;
702 	if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT)
703 		dst->src_port = ports[0];
704 	if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT)
705 		dst->dst_port = ports[1];
706 	return 0;
707 }
708 
hashlimit_byte_cost(unsigned int len,struct dsthash_ent * dh)709 static u32 hashlimit_byte_cost(unsigned int len, struct dsthash_ent *dh)
710 {
711 	u64 tmp = xt_hashlimit_len_to_chunks(len);
712 	tmp = tmp * dh->rateinfo.cost;
713 
714 	if (unlikely(tmp > CREDITS_PER_JIFFY_BYTES * HZ))
715 		tmp = CREDITS_PER_JIFFY_BYTES * HZ;
716 
717 	if (dh->rateinfo.credit < tmp && dh->rateinfo.credit_cap) {
718 		dh->rateinfo.credit_cap--;
719 		dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
720 	}
721 	return (u32) tmp;
722 }
723 
724 static bool
hashlimit_mt_common(const struct sk_buff * skb,struct xt_action_param * par,struct xt_hashlimit_htable * hinfo,const struct hashlimit_cfg3 * cfg,int revision)725 hashlimit_mt_common(const struct sk_buff *skb, struct xt_action_param *par,
726 		    struct xt_hashlimit_htable *hinfo,
727 		    const struct hashlimit_cfg3 *cfg, int revision)
728 {
729 	unsigned long now = jiffies;
730 	struct dsthash_ent *dh;
731 	struct dsthash_dst dst;
732 	bool race = false;
733 	u64 cost;
734 
735 	if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0)
736 		goto hotdrop;
737 
738 	local_bh_disable();
739 	dh = dsthash_find(hinfo, &dst);
740 	if (dh == NULL) {
741 		dh = dsthash_alloc_init(hinfo, &dst, &race);
742 		if (dh == NULL) {
743 			local_bh_enable();
744 			goto hotdrop;
745 		} else if (race) {
746 			/* Already got an entry, update expiration timeout */
747 			dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
748 			rateinfo_recalc(dh, now, hinfo->cfg.mode, revision);
749 		} else {
750 			dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
751 			rateinfo_init(dh, hinfo, revision);
752 		}
753 	} else {
754 		/* update expiration timeout */
755 		dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
756 		rateinfo_recalc(dh, now, hinfo->cfg.mode, revision);
757 	}
758 
759 	if (cfg->mode & XT_HASHLIMIT_RATE_MATCH) {
760 		cost = (cfg->mode & XT_HASHLIMIT_BYTES) ? skb->len : 1;
761 		dh->rateinfo.current_rate += cost;
762 
763 		if (!dh->rateinfo.prev_window &&
764 		    (dh->rateinfo.current_rate <= dh->rateinfo.burst)) {
765 			spin_unlock(&dh->lock);
766 			local_bh_enable();
767 			return !(cfg->mode & XT_HASHLIMIT_INVERT);
768 		} else {
769 			goto overlimit;
770 		}
771 	}
772 
773 	if (cfg->mode & XT_HASHLIMIT_BYTES)
774 		cost = hashlimit_byte_cost(skb->len, dh);
775 	else
776 		cost = dh->rateinfo.cost;
777 
778 	if (dh->rateinfo.credit >= cost) {
779 		/* below the limit */
780 		dh->rateinfo.credit -= cost;
781 		spin_unlock(&dh->lock);
782 		local_bh_enable();
783 		return !(cfg->mode & XT_HASHLIMIT_INVERT);
784 	}
785 
786 overlimit:
787 	spin_unlock(&dh->lock);
788 	local_bh_enable();
789 	/* default match is underlimit - so over the limit, we need to invert */
790 	return cfg->mode & XT_HASHLIMIT_INVERT;
791 
792  hotdrop:
793 	par->hotdrop = true;
794 	return false;
795 }
796 
797 static bool
hashlimit_mt_v1(const struct sk_buff * skb,struct xt_action_param * par)798 hashlimit_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
799 {
800 	const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
801 	struct xt_hashlimit_htable *hinfo = info->hinfo;
802 	struct hashlimit_cfg3 cfg = {};
803 	int ret;
804 
805 	ret = cfg_copy(&cfg, (void *)&info->cfg, 1);
806 	if (ret)
807 		return ret;
808 
809 	return hashlimit_mt_common(skb, par, hinfo, &cfg, 1);
810 }
811 
812 static bool
hashlimit_mt_v2(const struct sk_buff * skb,struct xt_action_param * par)813 hashlimit_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
814 {
815 	const struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
816 	struct xt_hashlimit_htable *hinfo = info->hinfo;
817 	struct hashlimit_cfg3 cfg = {};
818 	int ret;
819 
820 	ret = cfg_copy(&cfg, (void *)&info->cfg, 2);
821 	if (ret)
822 		return ret;
823 
824 	return hashlimit_mt_common(skb, par, hinfo, &cfg, 2);
825 }
826 
827 static bool
hashlimit_mt(const struct sk_buff * skb,struct xt_action_param * par)828 hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par)
829 {
830 	const struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
831 	struct xt_hashlimit_htable *hinfo = info->hinfo;
832 
833 	return hashlimit_mt_common(skb, par, hinfo, &info->cfg, 3);
834 }
835 
836 #define HASHLIMIT_MAX_SIZE 1048576
837 
hashlimit_mt_check_common(const struct xt_mtchk_param * par,struct xt_hashlimit_htable ** hinfo,struct hashlimit_cfg3 * cfg,const char * name,int revision)838 static int hashlimit_mt_check_common(const struct xt_mtchk_param *par,
839 				     struct xt_hashlimit_htable **hinfo,
840 				     struct hashlimit_cfg3 *cfg,
841 				     const char *name, int revision)
842 {
843 	struct net *net = par->net;
844 	int ret;
845 
846 	if (cfg->gc_interval == 0 || cfg->expire == 0)
847 		return -EINVAL;
848 	if (cfg->size > HASHLIMIT_MAX_SIZE) {
849 		cfg->size = HASHLIMIT_MAX_SIZE;
850 		pr_info_ratelimited("size too large, truncated to %u\n", cfg->size);
851 	}
852 	if (cfg->max > HASHLIMIT_MAX_SIZE) {
853 		cfg->max = HASHLIMIT_MAX_SIZE;
854 		pr_info_ratelimited("max too large, truncated to %u\n", cfg->max);
855 	}
856 	if (par->family == NFPROTO_IPV4) {
857 		if (cfg->srcmask > 32 || cfg->dstmask > 32)
858 			return -EINVAL;
859 	} else {
860 		if (cfg->srcmask > 128 || cfg->dstmask > 128)
861 			return -EINVAL;
862 	}
863 
864 	if (cfg->mode & ~XT_HASHLIMIT_ALL) {
865 		pr_info_ratelimited("Unknown mode mask %X, kernel too old?\n",
866 				    cfg->mode);
867 		return -EINVAL;
868 	}
869 
870 	/* Check for overflow. */
871 	if (revision >= 3 && cfg->mode & XT_HASHLIMIT_RATE_MATCH) {
872 		if (cfg->avg == 0 || cfg->avg > U32_MAX) {
873 			pr_info_ratelimited("invalid rate\n");
874 			return -ERANGE;
875 		}
876 
877 		if (cfg->interval == 0) {
878 			pr_info_ratelimited("invalid interval\n");
879 			return -EINVAL;
880 		}
881 	} else if (cfg->mode & XT_HASHLIMIT_BYTES) {
882 		if (user2credits_byte(cfg->avg) == 0) {
883 			pr_info_ratelimited("overflow, rate too high: %llu\n",
884 					    cfg->avg);
885 			return -EINVAL;
886 		}
887 	} else if (cfg->burst == 0 ||
888 		   user2credits(cfg->avg * cfg->burst, revision) <
889 		   user2credits(cfg->avg, revision)) {
890 		pr_info_ratelimited("overflow, try lower: %llu/%llu\n",
891 				    cfg->avg, cfg->burst);
892 		return -ERANGE;
893 	}
894 
895 	mutex_lock(&hashlimit_mutex);
896 	*hinfo = htable_find_get(net, name, par->family);
897 	if (*hinfo == NULL) {
898 		ret = htable_create(net, cfg, name, par->family,
899 				    hinfo, revision);
900 		if (ret < 0) {
901 			mutex_unlock(&hashlimit_mutex);
902 			return ret;
903 		}
904 	}
905 	mutex_unlock(&hashlimit_mutex);
906 
907 	return 0;
908 }
909 
hashlimit_mt_check_v1(const struct xt_mtchk_param * par)910 static int hashlimit_mt_check_v1(const struct xt_mtchk_param *par)
911 {
912 	struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
913 	struct hashlimit_cfg3 cfg = {};
914 	int ret;
915 
916 	ret = xt_check_proc_name(info->name, sizeof(info->name));
917 	if (ret)
918 		return ret;
919 
920 	ret = cfg_copy(&cfg, (void *)&info->cfg, 1);
921 	if (ret)
922 		return ret;
923 
924 	return hashlimit_mt_check_common(par, &info->hinfo,
925 					 &cfg, info->name, 1);
926 }
927 
hashlimit_mt_check_v2(const struct xt_mtchk_param * par)928 static int hashlimit_mt_check_v2(const struct xt_mtchk_param *par)
929 {
930 	struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
931 	struct hashlimit_cfg3 cfg = {};
932 	int ret;
933 
934 	ret = xt_check_proc_name(info->name, sizeof(info->name));
935 	if (ret)
936 		return ret;
937 
938 	ret = cfg_copy(&cfg, (void *)&info->cfg, 2);
939 	if (ret)
940 		return ret;
941 
942 	return hashlimit_mt_check_common(par, &info->hinfo,
943 					 &cfg, info->name, 2);
944 }
945 
hashlimit_mt_check(const struct xt_mtchk_param * par)946 static int hashlimit_mt_check(const struct xt_mtchk_param *par)
947 {
948 	struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
949 	int ret;
950 
951 	ret = xt_check_proc_name(info->name, sizeof(info->name));
952 	if (ret)
953 		return ret;
954 
955 	return hashlimit_mt_check_common(par, &info->hinfo, &info->cfg,
956 					 info->name, 3);
957 }
958 
hashlimit_mt_destroy_v2(const struct xt_mtdtor_param * par)959 static void hashlimit_mt_destroy_v2(const struct xt_mtdtor_param *par)
960 {
961 	const struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
962 
963 	htable_put(info->hinfo);
964 }
965 
hashlimit_mt_destroy_v1(const struct xt_mtdtor_param * par)966 static void hashlimit_mt_destroy_v1(const struct xt_mtdtor_param *par)
967 {
968 	const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
969 
970 	htable_put(info->hinfo);
971 }
972 
hashlimit_mt_destroy(const struct xt_mtdtor_param * par)973 static void hashlimit_mt_destroy(const struct xt_mtdtor_param *par)
974 {
975 	const struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
976 
977 	htable_put(info->hinfo);
978 }
979 
980 static struct xt_match hashlimit_mt_reg[] __read_mostly = {
981 	{
982 		.name           = "hashlimit",
983 		.revision       = 1,
984 		.family         = NFPROTO_IPV4,
985 		.match          = hashlimit_mt_v1,
986 		.matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
987 		.usersize	= offsetof(struct xt_hashlimit_mtinfo1, hinfo),
988 		.checkentry     = hashlimit_mt_check_v1,
989 		.destroy        = hashlimit_mt_destroy_v1,
990 		.me             = THIS_MODULE,
991 	},
992 	{
993 		.name           = "hashlimit",
994 		.revision       = 2,
995 		.family         = NFPROTO_IPV4,
996 		.match          = hashlimit_mt_v2,
997 		.matchsize      = sizeof(struct xt_hashlimit_mtinfo2),
998 		.usersize	= offsetof(struct xt_hashlimit_mtinfo2, hinfo),
999 		.checkentry     = hashlimit_mt_check_v2,
1000 		.destroy        = hashlimit_mt_destroy_v2,
1001 		.me             = THIS_MODULE,
1002 	},
1003 	{
1004 		.name           = "hashlimit",
1005 		.revision       = 3,
1006 		.family         = NFPROTO_IPV4,
1007 		.match          = hashlimit_mt,
1008 		.matchsize      = sizeof(struct xt_hashlimit_mtinfo3),
1009 		.usersize	= offsetof(struct xt_hashlimit_mtinfo3, hinfo),
1010 		.checkentry     = hashlimit_mt_check,
1011 		.destroy        = hashlimit_mt_destroy,
1012 		.me             = THIS_MODULE,
1013 	},
1014 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1015 	{
1016 		.name           = "hashlimit",
1017 		.revision       = 1,
1018 		.family         = NFPROTO_IPV6,
1019 		.match          = hashlimit_mt_v1,
1020 		.matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
1021 		.usersize	= offsetof(struct xt_hashlimit_mtinfo1, hinfo),
1022 		.checkentry     = hashlimit_mt_check_v1,
1023 		.destroy        = hashlimit_mt_destroy_v1,
1024 		.me             = THIS_MODULE,
1025 	},
1026 	{
1027 		.name           = "hashlimit",
1028 		.revision       = 2,
1029 		.family         = NFPROTO_IPV6,
1030 		.match          = hashlimit_mt_v2,
1031 		.matchsize      = sizeof(struct xt_hashlimit_mtinfo2),
1032 		.usersize	= offsetof(struct xt_hashlimit_mtinfo2, hinfo),
1033 		.checkentry     = hashlimit_mt_check_v2,
1034 		.destroy        = hashlimit_mt_destroy_v2,
1035 		.me             = THIS_MODULE,
1036 	},
1037 	{
1038 		.name           = "hashlimit",
1039 		.revision       = 3,
1040 		.family         = NFPROTO_IPV6,
1041 		.match          = hashlimit_mt,
1042 		.matchsize      = sizeof(struct xt_hashlimit_mtinfo3),
1043 		.usersize	= offsetof(struct xt_hashlimit_mtinfo3, hinfo),
1044 		.checkentry     = hashlimit_mt_check,
1045 		.destroy        = hashlimit_mt_destroy,
1046 		.me             = THIS_MODULE,
1047 	},
1048 #endif
1049 };
1050 
1051 /* PROC stuff */
dl_seq_start(struct seq_file * s,loff_t * pos)1052 static void *dl_seq_start(struct seq_file *s, loff_t *pos)
1053 	__acquires(htable->lock)
1054 {
1055 	struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file));
1056 	unsigned int *bucket;
1057 
1058 	spin_lock_bh(&htable->lock);
1059 	if (*pos >= htable->cfg.size)
1060 		return NULL;
1061 
1062 	bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
1063 	if (!bucket)
1064 		return ERR_PTR(-ENOMEM);
1065 
1066 	*bucket = *pos;
1067 	return bucket;
1068 }
1069 
dl_seq_next(struct seq_file * s,void * v,loff_t * pos)1070 static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
1071 {
1072 	struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file));
1073 	unsigned int *bucket = v;
1074 
1075 	*pos = ++(*bucket);
1076 	if (*pos >= htable->cfg.size) {
1077 		kfree(v);
1078 		return NULL;
1079 	}
1080 	return bucket;
1081 }
1082 
dl_seq_stop(struct seq_file * s,void * v)1083 static void dl_seq_stop(struct seq_file *s, void *v)
1084 	__releases(htable->lock)
1085 {
1086 	struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file));
1087 	unsigned int *bucket = v;
1088 
1089 	if (!IS_ERR(bucket))
1090 		kfree(bucket);
1091 	spin_unlock_bh(&htable->lock);
1092 }
1093 
dl_seq_print(struct dsthash_ent * ent,u_int8_t family,struct seq_file * s)1094 static void dl_seq_print(struct dsthash_ent *ent, u_int8_t family,
1095 			 struct seq_file *s)
1096 {
1097 	switch (family) {
1098 	case NFPROTO_IPV4:
1099 		seq_printf(s, "%ld %pI4:%u->%pI4:%u %llu %llu %llu\n",
1100 			   (long)(ent->expires - jiffies)/HZ,
1101 			   &ent->dst.ip.src,
1102 			   ntohs(ent->dst.src_port),
1103 			   &ent->dst.ip.dst,
1104 			   ntohs(ent->dst.dst_port),
1105 			   ent->rateinfo.credit, ent->rateinfo.credit_cap,
1106 			   ent->rateinfo.cost);
1107 		break;
1108 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1109 	case NFPROTO_IPV6:
1110 		seq_printf(s, "%ld %pI6:%u->%pI6:%u %llu %llu %llu\n",
1111 			   (long)(ent->expires - jiffies)/HZ,
1112 			   &ent->dst.ip6.src,
1113 			   ntohs(ent->dst.src_port),
1114 			   &ent->dst.ip6.dst,
1115 			   ntohs(ent->dst.dst_port),
1116 			   ent->rateinfo.credit, ent->rateinfo.credit_cap,
1117 			   ent->rateinfo.cost);
1118 		break;
1119 #endif
1120 	default:
1121 		BUG();
1122 	}
1123 }
1124 
dl_seq_real_show_v2(struct dsthash_ent * ent,u_int8_t family,struct seq_file * s)1125 static int dl_seq_real_show_v2(struct dsthash_ent *ent, u_int8_t family,
1126 			       struct seq_file *s)
1127 {
1128 	struct xt_hashlimit_htable *ht = pde_data(file_inode(s->file));
1129 
1130 	spin_lock(&ent->lock);
1131 	/* recalculate to show accurate numbers */
1132 	rateinfo_recalc(ent, jiffies, ht->cfg.mode, 2);
1133 
1134 	dl_seq_print(ent, family, s);
1135 
1136 	spin_unlock(&ent->lock);
1137 	return seq_has_overflowed(s);
1138 }
1139 
dl_seq_real_show_v1(struct dsthash_ent * ent,u_int8_t family,struct seq_file * s)1140 static int dl_seq_real_show_v1(struct dsthash_ent *ent, u_int8_t family,
1141 			       struct seq_file *s)
1142 {
1143 	struct xt_hashlimit_htable *ht = pde_data(file_inode(s->file));
1144 
1145 	spin_lock(&ent->lock);
1146 	/* recalculate to show accurate numbers */
1147 	rateinfo_recalc(ent, jiffies, ht->cfg.mode, 1);
1148 
1149 	dl_seq_print(ent, family, s);
1150 
1151 	spin_unlock(&ent->lock);
1152 	return seq_has_overflowed(s);
1153 }
1154 
dl_seq_real_show(struct dsthash_ent * ent,u_int8_t family,struct seq_file * s)1155 static int dl_seq_real_show(struct dsthash_ent *ent, u_int8_t family,
1156 			    struct seq_file *s)
1157 {
1158 	struct xt_hashlimit_htable *ht = pde_data(file_inode(s->file));
1159 
1160 	spin_lock(&ent->lock);
1161 	/* recalculate to show accurate numbers */
1162 	rateinfo_recalc(ent, jiffies, ht->cfg.mode, 3);
1163 
1164 	dl_seq_print(ent, family, s);
1165 
1166 	spin_unlock(&ent->lock);
1167 	return seq_has_overflowed(s);
1168 }
1169 
dl_seq_show_v2(struct seq_file * s,void * v)1170 static int dl_seq_show_v2(struct seq_file *s, void *v)
1171 {
1172 	struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file));
1173 	unsigned int *bucket = (unsigned int *)v;
1174 	struct dsthash_ent *ent;
1175 
1176 	if (!hlist_empty(&htable->hash[*bucket])) {
1177 		hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1178 			if (dl_seq_real_show_v2(ent, htable->family, s))
1179 				return -1;
1180 	}
1181 	return 0;
1182 }
1183 
dl_seq_show_v1(struct seq_file * s,void * v)1184 static int dl_seq_show_v1(struct seq_file *s, void *v)
1185 {
1186 	struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file));
1187 	unsigned int *bucket = v;
1188 	struct dsthash_ent *ent;
1189 
1190 	if (!hlist_empty(&htable->hash[*bucket])) {
1191 		hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1192 			if (dl_seq_real_show_v1(ent, htable->family, s))
1193 				return -1;
1194 	}
1195 	return 0;
1196 }
1197 
dl_seq_show(struct seq_file * s,void * v)1198 static int dl_seq_show(struct seq_file *s, void *v)
1199 {
1200 	struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file));
1201 	unsigned int *bucket = v;
1202 	struct dsthash_ent *ent;
1203 
1204 	if (!hlist_empty(&htable->hash[*bucket])) {
1205 		hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1206 			if (dl_seq_real_show(ent, htable->family, s))
1207 				return -1;
1208 	}
1209 	return 0;
1210 }
1211 
1212 static const struct seq_operations dl_seq_ops_v1 = {
1213 	.start = dl_seq_start,
1214 	.next  = dl_seq_next,
1215 	.stop  = dl_seq_stop,
1216 	.show  = dl_seq_show_v1
1217 };
1218 
1219 static const struct seq_operations dl_seq_ops_v2 = {
1220 	.start = dl_seq_start,
1221 	.next  = dl_seq_next,
1222 	.stop  = dl_seq_stop,
1223 	.show  = dl_seq_show_v2
1224 };
1225 
1226 static const struct seq_operations dl_seq_ops = {
1227 	.start = dl_seq_start,
1228 	.next  = dl_seq_next,
1229 	.stop  = dl_seq_stop,
1230 	.show  = dl_seq_show
1231 };
1232 
hashlimit_proc_net_init(struct net * net)1233 static int __net_init hashlimit_proc_net_init(struct net *net)
1234 {
1235 	struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1236 
1237 	hashlimit_net->ipt_hashlimit = proc_mkdir("ipt_hashlimit", net->proc_net);
1238 	if (!hashlimit_net->ipt_hashlimit)
1239 		return -ENOMEM;
1240 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1241 	hashlimit_net->ip6t_hashlimit = proc_mkdir("ip6t_hashlimit", net->proc_net);
1242 	if (!hashlimit_net->ip6t_hashlimit) {
1243 		remove_proc_entry("ipt_hashlimit", net->proc_net);
1244 		return -ENOMEM;
1245 	}
1246 #endif
1247 	return 0;
1248 }
1249 
hashlimit_proc_net_exit(struct net * net)1250 static void __net_exit hashlimit_proc_net_exit(struct net *net)
1251 {
1252 	struct xt_hashlimit_htable *hinfo;
1253 	struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1254 
1255 	/* hashlimit_net_exit() is called before hashlimit_mt_destroy().
1256 	 * Make sure that the parent ipt_hashlimit and ip6t_hashlimit proc
1257 	 * entries is empty before trying to remove it.
1258 	 */
1259 	mutex_lock(&hashlimit_mutex);
1260 	hlist_for_each_entry(hinfo, &hashlimit_net->htables, node)
1261 		htable_remove_proc_entry(hinfo);
1262 	hashlimit_net->ipt_hashlimit = NULL;
1263 	hashlimit_net->ip6t_hashlimit = NULL;
1264 	mutex_unlock(&hashlimit_mutex);
1265 
1266 	remove_proc_entry("ipt_hashlimit", net->proc_net);
1267 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1268 	remove_proc_entry("ip6t_hashlimit", net->proc_net);
1269 #endif
1270 }
1271 
hashlimit_net_init(struct net * net)1272 static int __net_init hashlimit_net_init(struct net *net)
1273 {
1274 	struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1275 
1276 	INIT_HLIST_HEAD(&hashlimit_net->htables);
1277 	return hashlimit_proc_net_init(net);
1278 }
1279 
hashlimit_net_exit(struct net * net)1280 static void __net_exit hashlimit_net_exit(struct net *net)
1281 {
1282 	hashlimit_proc_net_exit(net);
1283 }
1284 
1285 static struct pernet_operations hashlimit_net_ops = {
1286 	.init	= hashlimit_net_init,
1287 	.exit	= hashlimit_net_exit,
1288 	.id	= &hashlimit_net_id,
1289 	.size	= sizeof(struct hashlimit_net),
1290 };
1291 
hashlimit_mt_init(void)1292 static int __init hashlimit_mt_init(void)
1293 {
1294 	int err;
1295 
1296 	err = register_pernet_subsys(&hashlimit_net_ops);
1297 	if (err < 0)
1298 		return err;
1299 	err = xt_register_matches(hashlimit_mt_reg,
1300 	      ARRAY_SIZE(hashlimit_mt_reg));
1301 	if (err < 0)
1302 		goto err1;
1303 
1304 	err = -ENOMEM;
1305 	hashlimit_cachep = kmem_cache_create("xt_hashlimit",
1306 					    sizeof(struct dsthash_ent), 0, 0,
1307 					    NULL);
1308 	if (!hashlimit_cachep) {
1309 		pr_warn("unable to create slab cache\n");
1310 		goto err2;
1311 	}
1312 	return 0;
1313 
1314 err2:
1315 	xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
1316 err1:
1317 	unregister_pernet_subsys(&hashlimit_net_ops);
1318 	return err;
1319 
1320 }
1321 
hashlimit_mt_exit(void)1322 static void __exit hashlimit_mt_exit(void)
1323 {
1324 	xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
1325 	unregister_pernet_subsys(&hashlimit_net_ops);
1326 
1327 	rcu_barrier();
1328 	kmem_cache_destroy(hashlimit_cachep);
1329 }
1330 
1331 module_init(hashlimit_mt_init);
1332 module_exit(hashlimit_mt_exit);
1333