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1/*
2 * xt_hashlimit - Netfilter module to limit the number of packets per time
3 * separately for each hashbucket (sourceip/sourceport/dstip/dstport)
4 *
5 * (C) 2003-2004 by Harald Welte <laforge@netfilter.org>
6 * Copyright © CC Computer Consultants GmbH, 2007 - 2008
7 *
8 * Development of this code was funded by Astaro AG, http://www.astaro.com/
9 */
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11#include <linux/module.h>
12#include <linux/spinlock.h>
13#include <linux/random.h>
14#include <linux/jhash.h>
15#include <linux/slab.h>
16#include <linux/vmalloc.h>
17#include <linux/proc_fs.h>
18#include <linux/seq_file.h>
19#include <linux/list.h>
20#include <linux/skbuff.h>
21#include <linux/mm.h>
22#include <linux/in.h>
23#include <linux/ip.h>
24#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
25#include <linux/ipv6.h>
26#include <net/ipv6.h>
27#endif
28
29#include <net/net_namespace.h>
30#include <net/netns/generic.h>
31
32#include <linux/netfilter/x_tables.h>
33#include <linux/netfilter_ipv4/ip_tables.h>
34#include <linux/netfilter_ipv6/ip6_tables.h>
35#include <linux/netfilter/xt_hashlimit.h>
36#include <linux/mutex.h>
37
38MODULE_LICENSE("GPL");
39MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
40MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
41MODULE_DESCRIPTION("Xtables: per hash-bucket rate-limit match");
42MODULE_ALIAS("ipt_hashlimit");
43MODULE_ALIAS("ip6t_hashlimit");
44
45struct hashlimit_net {
46 struct hlist_head htables;
47 struct proc_dir_entry *ipt_hashlimit;
48 struct proc_dir_entry *ip6t_hashlimit;
49};
50
51static int hashlimit_net_id;
52static inline struct hashlimit_net *hashlimit_pernet(struct net *net)
53{
54 return net_generic(net, hashlimit_net_id);
55}
56
57/* need to declare this at the top */
58static const struct file_operations dl_file_ops;
59
60/* hash table crap */
61struct dsthash_dst {
62 union {
63 struct {
64 __be32 src;
65 __be32 dst;
66 } ip;
67#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
68 struct {
69 __be32 src[4];
70 __be32 dst[4];
71 } ip6;
72#endif
73 };
74 __be16 src_port;
75 __be16 dst_port;
76};
77
78struct dsthash_ent {
79 /* static / read-only parts in the beginning */
80 struct hlist_node node;
81 struct dsthash_dst dst;
82
83 /* modified structure members in the end */
84 spinlock_t lock;
85 unsigned long expires; /* precalculated expiry time */
86 struct {
87 unsigned long prev; /* last modification */
88 u_int32_t credit;
89 u_int32_t credit_cap, cost;
90 } rateinfo;
91 struct rcu_head rcu;
92};
93
94struct xt_hashlimit_htable {
95 struct hlist_node node; /* global list of all htables */
96 int use;
97 u_int8_t family;
98 bool rnd_initialized;
99
100 struct hashlimit_cfg1 cfg; /* config */
101
102 /* used internally */
103 spinlock_t lock; /* lock for list_head */
104 u_int32_t rnd; /* random seed for hash */
105 unsigned int count; /* number entries in table */
106 struct timer_list timer; /* timer for gc */
107
108 /* seq_file stuff */
109 struct proc_dir_entry *pde;
110 struct net *net;
111
112 struct hlist_head hash[0]; /* hashtable itself */
113};
114
115static DEFINE_MUTEX(hashlimit_mutex); /* protects htables list */
116static struct kmem_cache *hashlimit_cachep __read_mostly;
117
118static inline bool dst_cmp(const struct dsthash_ent *ent,
119 const struct dsthash_dst *b)
120{
121 return !memcmp(&ent->dst, b, sizeof(ent->dst));
122}
123
124static u_int32_t
125hash_dst(const struct xt_hashlimit_htable *ht, const struct dsthash_dst *dst)
126{
127 u_int32_t hash = jhash2((const u32 *)dst,
128 sizeof(*dst)/sizeof(u32),
129 ht->rnd);
130 /*
131 * Instead of returning hash % ht->cfg.size (implying a divide)
132 * we return the high 32 bits of the (hash * ht->cfg.size) that will
133 * give results between [0 and cfg.size-1] and same hash distribution,
134 * but using a multiply, less expensive than a divide
135 */
136 return ((u64)hash * ht->cfg.size) >> 32;
137}
138
139static struct dsthash_ent *
140dsthash_find(const struct xt_hashlimit_htable *ht,
141 const struct dsthash_dst *dst)
142{
143 struct dsthash_ent *ent;
144 struct hlist_node *pos;
145 u_int32_t hash = hash_dst(ht, dst);
146
147 if (!hlist_empty(&ht->hash[hash])) {
148 hlist_for_each_entry_rcu(ent, pos, &ht->hash[hash], node)
149 if (dst_cmp(ent, dst)) {
150 spin_lock(&ent->lock);
151 return ent;
152 }
153 }
154 return NULL;
155}
156
157/* allocate dsthash_ent, initialize dst, put in htable and lock it */
158static struct dsthash_ent *
159dsthash_alloc_init(struct xt_hashlimit_htable *ht,
160 const struct dsthash_dst *dst)
161{
162 struct dsthash_ent *ent;
163
164 spin_lock(&ht->lock);
165 /* initialize hash with random val at the time we allocate
166 * the first hashtable entry */
167 if (unlikely(!ht->rnd_initialized)) {
168 get_random_bytes(&ht->rnd, sizeof(ht->rnd));
169 ht->rnd_initialized = true;
170 }
171
172 if (ht->cfg.max && ht->count >= ht->cfg.max) {
173 /* FIXME: do something. question is what.. */
174 net_err_ratelimited("max count of %u reached\n", ht->cfg.max);
175 ent = NULL;
176 } else
177 ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
178 if (ent) {
179 memcpy(&ent->dst, dst, sizeof(ent->dst));
180 spin_lock_init(&ent->lock);
181
182 spin_lock(&ent->lock);
183 hlist_add_head_rcu(&ent->node, &ht->hash[hash_dst(ht, dst)]);
184 ht->count++;
185 }
186 spin_unlock(&ht->lock);
187 return ent;
188}
189
190static void dsthash_free_rcu(struct rcu_head *head)
191{
192 struct dsthash_ent *ent = container_of(head, struct dsthash_ent, rcu);
193
194 kmem_cache_free(hashlimit_cachep, ent);
195}
196
197static inline void
198dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent)
199{
200 hlist_del_rcu(&ent->node);
201 call_rcu_bh(&ent->rcu, dsthash_free_rcu);
202 ht->count--;
203}
204static void htable_gc(unsigned long htlong);
205
206static int htable_create(struct net *net, struct xt_hashlimit_mtinfo1 *minfo,
207 u_int8_t family)
208{
209 struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
210 struct xt_hashlimit_htable *hinfo;
211 unsigned int size;
212 unsigned int i;
213
214 if (minfo->cfg.size) {
215 size = minfo->cfg.size;
216 } else {
217 size = (totalram_pages << PAGE_SHIFT) / 16384 /
218 sizeof(struct list_head);
219 if (totalram_pages > 1024 * 1024 * 1024 / PAGE_SIZE)
220 size = 8192;
221 if (size < 16)
222 size = 16;
223 }
224 /* FIXME: don't use vmalloc() here or anywhere else -HW */
225 hinfo = vmalloc(sizeof(struct xt_hashlimit_htable) +
226 sizeof(struct list_head) * size);
227 if (hinfo == NULL)
228 return -ENOMEM;
229 minfo->hinfo = hinfo;
230
231 /* copy match config into hashtable config */
232 memcpy(&hinfo->cfg, &minfo->cfg, sizeof(hinfo->cfg));
233 hinfo->cfg.size = size;
234 if (hinfo->cfg.max == 0)
235 hinfo->cfg.max = 8 * hinfo->cfg.size;
236 else if (hinfo->cfg.max < hinfo->cfg.size)
237 hinfo->cfg.max = hinfo->cfg.size;
238
239 for (i = 0; i < hinfo->cfg.size; i++)
240 INIT_HLIST_HEAD(&hinfo->hash[i]);
241
242 hinfo->use = 1;
243 hinfo->count = 0;
244 hinfo->family = family;
245 hinfo->rnd_initialized = false;
246 spin_lock_init(&hinfo->lock);
247
248 hinfo->pde = proc_create_data(minfo->name, 0,
249 (family == NFPROTO_IPV4) ?
250 hashlimit_net->ipt_hashlimit : hashlimit_net->ip6t_hashlimit,
251 &dl_file_ops, hinfo);
252 if (hinfo->pde == NULL) {
253 vfree(hinfo);
254 return -ENOMEM;
255 }
256 hinfo->net = net;
257
258 setup_timer(&hinfo->timer, htable_gc, (unsigned long)hinfo);
259 hinfo->timer.expires = jiffies + msecs_to_jiffies(hinfo->cfg.gc_interval);
260 add_timer(&hinfo->timer);
261
262 hlist_add_head(&hinfo->node, &hashlimit_net->htables);
263
264 return 0;
265}
266
267static bool select_all(const struct xt_hashlimit_htable *ht,
268 const struct dsthash_ent *he)
269{
270 return 1;
271}
272
273static bool select_gc(const struct xt_hashlimit_htable *ht,
274 const struct dsthash_ent *he)
275{
276 return time_after_eq(jiffies, he->expires);
277}
278
279static void htable_selective_cleanup(struct xt_hashlimit_htable *ht,
280 bool (*select)(const struct xt_hashlimit_htable *ht,
281 const struct dsthash_ent *he))
282{
283 unsigned int i;
284
285 /* lock hash table and iterate over it */
286 spin_lock_bh(&ht->lock);
287 for (i = 0; i < ht->cfg.size; i++) {
288 struct dsthash_ent *dh;
289 struct hlist_node *pos, *n;
290 hlist_for_each_entry_safe(dh, pos, n, &ht->hash[i], node) {
291 if ((*select)(ht, dh))
292 dsthash_free(ht, dh);
293 }
294 }
295 spin_unlock_bh(&ht->lock);
296}
297
298/* hash table garbage collector, run by timer */
299static void htable_gc(unsigned long htlong)
300{
301 struct xt_hashlimit_htable *ht = (struct xt_hashlimit_htable *)htlong;
302
303 htable_selective_cleanup(ht, select_gc);
304
305 /* re-add the timer accordingly */
306 ht->timer.expires = jiffies + msecs_to_jiffies(ht->cfg.gc_interval);
307 add_timer(&ht->timer);
308}
309
310static void htable_destroy(struct xt_hashlimit_htable *hinfo)
311{
312 struct hashlimit_net *hashlimit_net = hashlimit_pernet(hinfo->net);
313 struct proc_dir_entry *parent;
314
315 del_timer_sync(&hinfo->timer);
316
317 if (hinfo->family == NFPROTO_IPV4)
318 parent = hashlimit_net->ipt_hashlimit;
319 else
320 parent = hashlimit_net->ip6t_hashlimit;
321 remove_proc_entry(hinfo->pde->name, parent);
322 htable_selective_cleanup(hinfo, select_all);
323 vfree(hinfo);
324}
325
326static struct xt_hashlimit_htable *htable_find_get(struct net *net,
327 const char *name,
328 u_int8_t family)
329{
330 struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
331 struct xt_hashlimit_htable *hinfo;
332 struct hlist_node *pos;
333
334 hlist_for_each_entry(hinfo, pos, &hashlimit_net->htables, node) {
335 if (!strcmp(name, hinfo->pde->name) &&
336 hinfo->family == family) {
337 hinfo->use++;
338 return hinfo;
339 }
340 }
341 return NULL;
342}
343
344static void htable_put(struct xt_hashlimit_htable *hinfo)
345{
346 mutex_lock(&hashlimit_mutex);
347 if (--hinfo->use == 0) {
348 hlist_del(&hinfo->node);
349 htable_destroy(hinfo);
350 }
351 mutex_unlock(&hashlimit_mutex);
352}
353
354/* The algorithm used is the Simple Token Bucket Filter (TBF)
355 * see net/sched/sch_tbf.c in the linux source tree
356 */
357
358/* Rusty: This is my (non-mathematically-inclined) understanding of
359 this algorithm. The `average rate' in jiffies becomes your initial
360 amount of credit `credit' and the most credit you can ever have
361 `credit_cap'. The `peak rate' becomes the cost of passing the
362 test, `cost'.
363
364 `prev' tracks the last packet hit: you gain one credit per jiffy.
365 If you get credit balance more than this, the extra credit is
366 discarded. Every time the match passes, you lose `cost' credits;
367 if you don't have that many, the test fails.
368
369 See Alexey's formal explanation in net/sched/sch_tbf.c.
370
371 To get the maximum range, we multiply by this factor (ie. you get N
372 credits per jiffy). We want to allow a rate as low as 1 per day
373 (slowest userspace tool allows), which means
374 CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
375*/
376#define MAX_CPJ (0xFFFFFFFF / (HZ*60*60*24))
377
378/* Repeated shift and or gives us all 1s, final shift and add 1 gives
379 * us the power of 2 below the theoretical max, so GCC simply does a
380 * shift. */
381#define _POW2_BELOW2(x) ((x)|((x)>>1))
382#define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
383#define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
384#define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
385#define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
386#define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
387
388#define CREDITS_PER_JIFFY POW2_BELOW32(MAX_CPJ)
389
390/* in byte mode, the lowest possible rate is one packet/second.
391 * credit_cap is used as a counter that tells us how many times we can
392 * refill the "credits available" counter when it becomes empty.
393 */
394#define MAX_CPJ_BYTES (0xFFFFFFFF / HZ)
395#define CREDITS_PER_JIFFY_BYTES POW2_BELOW32(MAX_CPJ_BYTES)
396
397static u32 xt_hashlimit_len_to_chunks(u32 len)
398{
399 return (len >> XT_HASHLIMIT_BYTE_SHIFT) + 1;
400}
401
402/* Precision saver. */
403static u32 user2credits(u32 user)
404{
405 /* If multiplying would overflow... */
406 if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY))
407 /* Divide first. */
408 return (user / XT_HASHLIMIT_SCALE) * HZ * CREDITS_PER_JIFFY;
409
410 return (user * HZ * CREDITS_PER_JIFFY) / XT_HASHLIMIT_SCALE;
411}
412
413static u32 user2credits_byte(u32 user)
414{
415 u64 us = user;
416 us *= HZ * CREDITS_PER_JIFFY_BYTES;
417 return (u32) (us >> 32);
418}
419
420static void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now, u32 mode)
421{
422 unsigned long delta = now - dh->rateinfo.prev;
423 u32 cap;
424
425 if (delta == 0)
426 return;
427
428 dh->rateinfo.prev = now;
429
430 if (mode & XT_HASHLIMIT_BYTES) {
431 u32 tmp = dh->rateinfo.credit;
432 dh->rateinfo.credit += CREDITS_PER_JIFFY_BYTES * delta;
433 cap = CREDITS_PER_JIFFY_BYTES * HZ;
434 if (tmp >= dh->rateinfo.credit) {/* overflow */
435 dh->rateinfo.credit = cap;
436 return;
437 }
438 } else {
439 dh->rateinfo.credit += delta * CREDITS_PER_JIFFY;
440 cap = dh->rateinfo.credit_cap;
441 }
442 if (dh->rateinfo.credit > cap)
443 dh->rateinfo.credit = cap;
444}
445
446static void rateinfo_init(struct dsthash_ent *dh,
447 struct xt_hashlimit_htable *hinfo)
448{
449 dh->rateinfo.prev = jiffies;
450 if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) {
451 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
452 dh->rateinfo.cost = user2credits_byte(hinfo->cfg.avg);
453 dh->rateinfo.credit_cap = hinfo->cfg.burst;
454 } else {
455 dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
456 hinfo->cfg.burst);
457 dh->rateinfo.cost = user2credits(hinfo->cfg.avg);
458 dh->rateinfo.credit_cap = dh->rateinfo.credit;
459 }
460}
461
462static inline __be32 maskl(__be32 a, unsigned int l)
463{
464 return l ? htonl(ntohl(a) & ~0 << (32 - l)) : 0;
465}
466
467#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
468static void hashlimit_ipv6_mask(__be32 *i, unsigned int p)
469{
470 switch (p) {
471 case 0 ... 31:
472 i[0] = maskl(i[0], p);
473 i[1] = i[2] = i[3] = 0;
474 break;
475 case 32 ... 63:
476 i[1] = maskl(i[1], p - 32);
477 i[2] = i[3] = 0;
478 break;
479 case 64 ... 95:
480 i[2] = maskl(i[2], p - 64);
481 i[3] = 0;
482 break;
483 case 96 ... 127:
484 i[3] = maskl(i[3], p - 96);
485 break;
486 case 128:
487 break;
488 }
489}
490#endif
491
492static int
493hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
494 struct dsthash_dst *dst,
495 const struct sk_buff *skb, unsigned int protoff)
496{
497 __be16 _ports[2], *ports;
498 u8 nexthdr;
499 int poff;
500
501 memset(dst, 0, sizeof(*dst));
502
503 switch (hinfo->family) {
504 case NFPROTO_IPV4:
505 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
506 dst->ip.dst = maskl(ip_hdr(skb)->daddr,
507 hinfo->cfg.dstmask);
508 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
509 dst->ip.src = maskl(ip_hdr(skb)->saddr,
510 hinfo->cfg.srcmask);
511
512 if (!(hinfo->cfg.mode &
513 (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
514 return 0;
515 nexthdr = ip_hdr(skb)->protocol;
516 break;
517#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
518 case NFPROTO_IPV6:
519 {
520 __be16 frag_off;
521
522 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) {
523 memcpy(&dst->ip6.dst, &ipv6_hdr(skb)->daddr,
524 sizeof(dst->ip6.dst));
525 hashlimit_ipv6_mask(dst->ip6.dst, hinfo->cfg.dstmask);
526 }
527 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) {
528 memcpy(&dst->ip6.src, &ipv6_hdr(skb)->saddr,
529 sizeof(dst->ip6.src));
530 hashlimit_ipv6_mask(dst->ip6.src, hinfo->cfg.srcmask);
531 }
532
533 if (!(hinfo->cfg.mode &
534 (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
535 return 0;
536 nexthdr = ipv6_hdr(skb)->nexthdr;
537 protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, &frag_off);
538 if ((int)protoff < 0)
539 return -1;
540 break;
541 }
542#endif
543 default:
544 BUG();
545 return 0;
546 }
547
548 poff = proto_ports_offset(nexthdr);
549 if (poff >= 0) {
550 ports = skb_header_pointer(skb, protoff + poff, sizeof(_ports),
551 &_ports);
552 } else {
553 _ports[0] = _ports[1] = 0;
554 ports = _ports;
555 }
556 if (!ports)
557 return -1;
558 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT)
559 dst->src_port = ports[0];
560 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT)
561 dst->dst_port = ports[1];
562 return 0;
563}
564
565static u32 hashlimit_byte_cost(unsigned int len, struct dsthash_ent *dh)
566{
567 u64 tmp = xt_hashlimit_len_to_chunks(len);
568 tmp = tmp * dh->rateinfo.cost;
569
570 if (unlikely(tmp > CREDITS_PER_JIFFY_BYTES * HZ))
571 tmp = CREDITS_PER_JIFFY_BYTES * HZ;
572
573 if (dh->rateinfo.credit < tmp && dh->rateinfo.credit_cap) {
574 dh->rateinfo.credit_cap--;
575 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
576 }
577 return (u32) tmp;
578}
579
580static bool
581hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par)
582{
583 const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
584 struct xt_hashlimit_htable *hinfo = info->hinfo;
585 unsigned long now = jiffies;
586 struct dsthash_ent *dh;
587 struct dsthash_dst dst;
588 u32 cost;
589
590 if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0)
591 goto hotdrop;
592
593 rcu_read_lock_bh();
594 dh = dsthash_find(hinfo, &dst);
595 if (dh == NULL) {
596 dh = dsthash_alloc_init(hinfo, &dst);
597 if (dh == NULL) {
598 rcu_read_unlock_bh();
599 goto hotdrop;
600 }
601 dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
602 rateinfo_init(dh, hinfo);
603 } else {
604 /* update expiration timeout */
605 dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
606 rateinfo_recalc(dh, now, hinfo->cfg.mode);
607 }
608
609 if (info->cfg.mode & XT_HASHLIMIT_BYTES)
610 cost = hashlimit_byte_cost(skb->len, dh);
611 else
612 cost = dh->rateinfo.cost;
613
614 if (dh->rateinfo.credit >= cost) {
615 /* below the limit */
616 dh->rateinfo.credit -= cost;
617 spin_unlock(&dh->lock);
618 rcu_read_unlock_bh();
619 return !(info->cfg.mode & XT_HASHLIMIT_INVERT);
620 }
621
622 spin_unlock(&dh->lock);
623 rcu_read_unlock_bh();
624 /* default match is underlimit - so over the limit, we need to invert */
625 return info->cfg.mode & XT_HASHLIMIT_INVERT;
626
627 hotdrop:
628 par->hotdrop = true;
629 return false;
630}
631
632static int hashlimit_mt_check(const struct xt_mtchk_param *par)
633{
634 struct net *net = par->net;
635 struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
636 int ret;
637
638 if (info->cfg.gc_interval == 0 || info->cfg.expire == 0)
639 return -EINVAL;
640 if (info->name[sizeof(info->name)-1] != '\0')
641 return -EINVAL;
642 if (par->family == NFPROTO_IPV4) {
643 if (info->cfg.srcmask > 32 || info->cfg.dstmask > 32)
644 return -EINVAL;
645 } else {
646 if (info->cfg.srcmask > 128 || info->cfg.dstmask > 128)
647 return -EINVAL;
648 }
649
650 if (info->cfg.mode & ~XT_HASHLIMIT_ALL) {
651 pr_info("Unknown mode mask %X, kernel too old?\n",
652 info->cfg.mode);
653 return -EINVAL;
654 }
655
656 /* Check for overflow. */
657 if (info->cfg.mode & XT_HASHLIMIT_BYTES) {
658 if (user2credits_byte(info->cfg.avg) == 0) {
659 pr_info("overflow, rate too high: %u\n", info->cfg.avg);
660 return -EINVAL;
661 }
662 } else if (info->cfg.burst == 0 ||
663 user2credits(info->cfg.avg * info->cfg.burst) <
664 user2credits(info->cfg.avg)) {
665 pr_info("overflow, try lower: %u/%u\n",
666 info->cfg.avg, info->cfg.burst);
667 return -ERANGE;
668 }
669
670 mutex_lock(&hashlimit_mutex);
671 info->hinfo = htable_find_get(net, info->name, par->family);
672 if (info->hinfo == NULL) {
673 ret = htable_create(net, info, par->family);
674 if (ret < 0) {
675 mutex_unlock(&hashlimit_mutex);
676 return ret;
677 }
678 }
679 mutex_unlock(&hashlimit_mutex);
680 return 0;
681}
682
683static void hashlimit_mt_destroy(const struct xt_mtdtor_param *par)
684{
685 const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
686
687 htable_put(info->hinfo);
688}
689
690static struct xt_match hashlimit_mt_reg[] __read_mostly = {
691 {
692 .name = "hashlimit",
693 .revision = 1,
694 .family = NFPROTO_IPV4,
695 .match = hashlimit_mt,
696 .matchsize = sizeof(struct xt_hashlimit_mtinfo1),
697 .checkentry = hashlimit_mt_check,
698 .destroy = hashlimit_mt_destroy,
699 .me = THIS_MODULE,
700 },
701#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
702 {
703 .name = "hashlimit",
704 .revision = 1,
705 .family = NFPROTO_IPV6,
706 .match = hashlimit_mt,
707 .matchsize = sizeof(struct xt_hashlimit_mtinfo1),
708 .checkentry = hashlimit_mt_check,
709 .destroy = hashlimit_mt_destroy,
710 .me = THIS_MODULE,
711 },
712#endif
713};
714
715/* PROC stuff */
716static void *dl_seq_start(struct seq_file *s, loff_t *pos)
717 __acquires(htable->lock)
718{
719 struct xt_hashlimit_htable *htable = s->private;
720 unsigned int *bucket;
721
722 spin_lock_bh(&htable->lock);
723 if (*pos >= htable->cfg.size)
724 return NULL;
725
726 bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
727 if (!bucket)
728 return ERR_PTR(-ENOMEM);
729
730 *bucket = *pos;
731 return bucket;
732}
733
734static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
735{
736 struct xt_hashlimit_htable *htable = s->private;
737 unsigned int *bucket = (unsigned int *)v;
738
739 *pos = ++(*bucket);
740 if (*pos >= htable->cfg.size) {
741 kfree(v);
742 return NULL;
743 }
744 return bucket;
745}
746
747static void dl_seq_stop(struct seq_file *s, void *v)
748 __releases(htable->lock)
749{
750 struct xt_hashlimit_htable *htable = s->private;
751 unsigned int *bucket = (unsigned int *)v;
752
753 if (!IS_ERR(bucket))
754 kfree(bucket);
755 spin_unlock_bh(&htable->lock);
756}
757
758static int dl_seq_real_show(struct dsthash_ent *ent, u_int8_t family,
759 struct seq_file *s)
760{
761 int res;
762 const struct xt_hashlimit_htable *ht = s->private;
763
764 spin_lock(&ent->lock);
765 /* recalculate to show accurate numbers */
766 rateinfo_recalc(ent, jiffies, ht->cfg.mode);
767
768 switch (family) {
769 case NFPROTO_IPV4:
770 res = seq_printf(s, "%ld %pI4:%u->%pI4:%u %u %u %u\n",
771 (long)(ent->expires - jiffies)/HZ,
772 &ent->dst.ip.src,
773 ntohs(ent->dst.src_port),
774 &ent->dst.ip.dst,
775 ntohs(ent->dst.dst_port),
776 ent->rateinfo.credit, ent->rateinfo.credit_cap,
777 ent->rateinfo.cost);
778 break;
779#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
780 case NFPROTO_IPV6:
781 res = seq_printf(s, "%ld %pI6:%u->%pI6:%u %u %u %u\n",
782 (long)(ent->expires - jiffies)/HZ,
783 &ent->dst.ip6.src,
784 ntohs(ent->dst.src_port),
785 &ent->dst.ip6.dst,
786 ntohs(ent->dst.dst_port),
787 ent->rateinfo.credit, ent->rateinfo.credit_cap,
788 ent->rateinfo.cost);
789 break;
790#endif
791 default:
792 BUG();
793 res = 0;
794 }
795 spin_unlock(&ent->lock);
796 return res;
797}
798
799static int dl_seq_show(struct seq_file *s, void *v)
800{
801 struct xt_hashlimit_htable *htable = s->private;
802 unsigned int *bucket = (unsigned int *)v;
803 struct dsthash_ent *ent;
804 struct hlist_node *pos;
805
806 if (!hlist_empty(&htable->hash[*bucket])) {
807 hlist_for_each_entry(ent, pos, &htable->hash[*bucket], node)
808 if (dl_seq_real_show(ent, htable->family, s))
809 return -1;
810 }
811 return 0;
812}
813
814static const struct seq_operations dl_seq_ops = {
815 .start = dl_seq_start,
816 .next = dl_seq_next,
817 .stop = dl_seq_stop,
818 .show = dl_seq_show
819};
820
821static int dl_proc_open(struct inode *inode, struct file *file)
822{
823 int ret = seq_open(file, &dl_seq_ops);
824
825 if (!ret) {
826 struct seq_file *sf = file->private_data;
827 sf->private = PDE(inode)->data;
828 }
829 return ret;
830}
831
832static const struct file_operations dl_file_ops = {
833 .owner = THIS_MODULE,
834 .open = dl_proc_open,
835 .read = seq_read,
836 .llseek = seq_lseek,
837 .release = seq_release
838};
839
840static int __net_init hashlimit_proc_net_init(struct net *net)
841{
842 struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
843
844 hashlimit_net->ipt_hashlimit = proc_mkdir("ipt_hashlimit", net->proc_net);
845 if (!hashlimit_net->ipt_hashlimit)
846 return -ENOMEM;
847#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
848 hashlimit_net->ip6t_hashlimit = proc_mkdir("ip6t_hashlimit", net->proc_net);
849 if (!hashlimit_net->ip6t_hashlimit) {
850 proc_net_remove(net, "ipt_hashlimit");
851 return -ENOMEM;
852 }
853#endif
854 return 0;
855}
856
857static void __net_exit hashlimit_proc_net_exit(struct net *net)
858{
859 proc_net_remove(net, "ipt_hashlimit");
860#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
861 proc_net_remove(net, "ip6t_hashlimit");
862#endif
863}
864
865static int __net_init hashlimit_net_init(struct net *net)
866{
867 struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
868
869 INIT_HLIST_HEAD(&hashlimit_net->htables);
870 return hashlimit_proc_net_init(net);
871}
872
873static void __net_exit hashlimit_net_exit(struct net *net)
874{
875 struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
876
877 BUG_ON(!hlist_empty(&hashlimit_net->htables));
878 hashlimit_proc_net_exit(net);
879}
880
881static struct pernet_operations hashlimit_net_ops = {
882 .init = hashlimit_net_init,
883 .exit = hashlimit_net_exit,
884 .id = &hashlimit_net_id,
885 .size = sizeof(struct hashlimit_net),
886};
887
888static int __init hashlimit_mt_init(void)
889{
890 int err;
891
892 err = register_pernet_subsys(&hashlimit_net_ops);
893 if (err < 0)
894 return err;
895 err = xt_register_matches(hashlimit_mt_reg,
896 ARRAY_SIZE(hashlimit_mt_reg));
897 if (err < 0)
898 goto err1;
899
900 err = -ENOMEM;
901 hashlimit_cachep = kmem_cache_create("xt_hashlimit",
902 sizeof(struct dsthash_ent), 0, 0,
903 NULL);
904 if (!hashlimit_cachep) {
905 pr_warning("unable to create slab cache\n");
906 goto err2;
907 }
908 return 0;
909
910err2:
911 xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
912err1:
913 unregister_pernet_subsys(&hashlimit_net_ops);
914 return err;
915
916}
917
918static void __exit hashlimit_mt_exit(void)
919{
920 xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
921 unregister_pernet_subsys(&hashlimit_net_ops);
922
923 rcu_barrier_bh();
924 kmem_cache_destroy(hashlimit_cachep);
925}
926
927module_init(hashlimit_mt_init);
928module_exit(hashlimit_mt_exit);