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Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi...
[deliverable/linux.git] / net / netfilter / xt_hashlimit.c
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 * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
7 * Copyright © CC Computer Consultants GmbH, 2007 - 2008
8 *
9 * Development of this code was funded by Astaro AG, http://www.astaro.com/
10 */
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12 #include <linux/module.h>
13 #include <linux/spinlock.h>
14 #include <linux/random.h>
15 #include <linux/jhash.h>
16 #include <linux/slab.h>
17 #include <linux/vmalloc.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/netfilter/xt_hashlimit.h>
37 #include <linux/mutex.h>
38
39 MODULE_LICENSE("GPL");
40 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
41 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
42 MODULE_DESCRIPTION("Xtables: per hash-bucket rate-limit match");
43 MODULE_ALIAS("ipt_hashlimit");
44 MODULE_ALIAS("ip6t_hashlimit");
45
46 struct hashlimit_net {
47 struct hlist_head htables;
48 struct proc_dir_entry *ipt_hashlimit;
49 struct proc_dir_entry *ip6t_hashlimit;
50 };
51
52 static int hashlimit_net_id;
53 static inline struct hashlimit_net *hashlimit_pernet(struct net *net)
54 {
55 return net_generic(net, hashlimit_net_id);
56 }
57
58 /* need to declare this at the top */
59 static const struct file_operations dl_file_ops;
60
61 /* hash table crap */
62 struct dsthash_dst {
63 union {
64 struct {
65 __be32 src;
66 __be32 dst;
67 } ip;
68 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
69 struct {
70 __be32 src[4];
71 __be32 dst[4];
72 } ip6;
73 #endif
74 };
75 __be16 src_port;
76 __be16 dst_port;
77 };
78
79 struct dsthash_ent {
80 /* static / read-only parts in the beginning */
81 struct hlist_node node;
82 struct dsthash_dst dst;
83
84 /* modified structure members in the end */
85 spinlock_t lock;
86 unsigned long expires; /* precalculated expiry time */
87 struct {
88 unsigned long prev; /* last modification */
89 u_int32_t credit;
90 u_int32_t credit_cap, cost;
91 } rateinfo;
92 struct rcu_head rcu;
93 };
94
95 struct xt_hashlimit_htable {
96 struct hlist_node node; /* global list of all htables */
97 int use;
98 u_int8_t family;
99 bool rnd_initialized;
100
101 struct hashlimit_cfg1 cfg; /* config */
102
103 /* used internally */
104 spinlock_t lock; /* lock for list_head */
105 u_int32_t rnd; /* random seed for hash */
106 unsigned int count; /* number entries in table */
107 struct delayed_work gc_work;
108
109 /* seq_file stuff */
110 struct proc_dir_entry *pde;
111 const char *name;
112 struct net *net;
113
114 struct hlist_head hash[0]; /* hashtable itself */
115 };
116
117 static DEFINE_MUTEX(hashlimit_mutex); /* protects htables list */
118 static struct kmem_cache *hashlimit_cachep __read_mostly;
119
120 static inline bool dst_cmp(const struct dsthash_ent *ent,
121 const struct dsthash_dst *b)
122 {
123 return !memcmp(&ent->dst, b, sizeof(ent->dst));
124 }
125
126 static u_int32_t
127 hash_dst(const struct xt_hashlimit_htable *ht, const struct dsthash_dst *dst)
128 {
129 u_int32_t hash = jhash2((const u32 *)dst,
130 sizeof(*dst)/sizeof(u32),
131 ht->rnd);
132 /*
133 * Instead of returning hash % ht->cfg.size (implying a divide)
134 * we return the high 32 bits of the (hash * ht->cfg.size) that will
135 * give results between [0 and cfg.size-1] and same hash distribution,
136 * but using a multiply, less expensive than a divide
137 */
138 return reciprocal_scale(hash, ht->cfg.size);
139 }
140
141 static struct dsthash_ent *
142 dsthash_find(const struct xt_hashlimit_htable *ht,
143 const struct dsthash_dst *dst)
144 {
145 struct dsthash_ent *ent;
146 u_int32_t hash = hash_dst(ht, dst);
147
148 if (!hlist_empty(&ht->hash[hash])) {
149 hlist_for_each_entry_rcu(ent, &ht->hash[hash], node)
150 if (dst_cmp(ent, dst)) {
151 spin_lock(&ent->lock);
152 return ent;
153 }
154 }
155 return NULL;
156 }
157
158 /* allocate dsthash_ent, initialize dst, put in htable and lock it */
159 static struct dsthash_ent *
160 dsthash_alloc_init(struct xt_hashlimit_htable *ht,
161 const struct dsthash_dst *dst, bool *race)
162 {
163 struct dsthash_ent *ent;
164
165 spin_lock(&ht->lock);
166
167 /* Two or more packets may race to create the same entry in the
168 * hashtable, double check if this packet lost race.
169 */
170 ent = dsthash_find(ht, dst);
171 if (ent != NULL) {
172 spin_unlock(&ht->lock);
173 *race = true;
174 return ent;
175 }
176
177 /* initialize hash with random val at the time we allocate
178 * the first hashtable entry */
179 if (unlikely(!ht->rnd_initialized)) {
180 get_random_bytes(&ht->rnd, sizeof(ht->rnd));
181 ht->rnd_initialized = true;
182 }
183
184 if (ht->cfg.max && ht->count >= ht->cfg.max) {
185 /* FIXME: do something. question is what.. */
186 net_err_ratelimited("max count of %u reached\n", ht->cfg.max);
187 ent = NULL;
188 } else
189 ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
190 if (ent) {
191 memcpy(&ent->dst, dst, sizeof(ent->dst));
192 spin_lock_init(&ent->lock);
193
194 spin_lock(&ent->lock);
195 hlist_add_head_rcu(&ent->node, &ht->hash[hash_dst(ht, dst)]);
196 ht->count++;
197 }
198 spin_unlock(&ht->lock);
199 return ent;
200 }
201
202 static void dsthash_free_rcu(struct rcu_head *head)
203 {
204 struct dsthash_ent *ent = container_of(head, struct dsthash_ent, rcu);
205
206 kmem_cache_free(hashlimit_cachep, ent);
207 }
208
209 static inline void
210 dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent)
211 {
212 hlist_del_rcu(&ent->node);
213 call_rcu_bh(&ent->rcu, dsthash_free_rcu);
214 ht->count--;
215 }
216 static void htable_gc(struct work_struct *work);
217
218 static int htable_create(struct net *net, struct xt_hashlimit_mtinfo1 *minfo,
219 u_int8_t family)
220 {
221 struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
222 struct xt_hashlimit_htable *hinfo;
223 unsigned int size;
224 unsigned int i;
225
226 if (minfo->cfg.size) {
227 size = minfo->cfg.size;
228 } else {
229 size = (totalram_pages << PAGE_SHIFT) / 16384 /
230 sizeof(struct list_head);
231 if (totalram_pages > 1024 * 1024 * 1024 / PAGE_SIZE)
232 size = 8192;
233 if (size < 16)
234 size = 16;
235 }
236 /* FIXME: don't use vmalloc() here or anywhere else -HW */
237 hinfo = vmalloc(sizeof(struct xt_hashlimit_htable) +
238 sizeof(struct list_head) * size);
239 if (hinfo == NULL)
240 return -ENOMEM;
241 minfo->hinfo = hinfo;
242
243 /* copy match config into hashtable config */
244 memcpy(&hinfo->cfg, &minfo->cfg, sizeof(hinfo->cfg));
245 hinfo->cfg.size = size;
246 if (hinfo->cfg.max == 0)
247 hinfo->cfg.max = 8 * hinfo->cfg.size;
248 else if (hinfo->cfg.max < hinfo->cfg.size)
249 hinfo->cfg.max = hinfo->cfg.size;
250
251 for (i = 0; i < hinfo->cfg.size; i++)
252 INIT_HLIST_HEAD(&hinfo->hash[i]);
253
254 hinfo->use = 1;
255 hinfo->count = 0;
256 hinfo->family = family;
257 hinfo->rnd_initialized = false;
258 hinfo->name = kstrdup(minfo->name, GFP_KERNEL);
259 if (!hinfo->name) {
260 vfree(hinfo);
261 return -ENOMEM;
262 }
263 spin_lock_init(&hinfo->lock);
264
265 hinfo->pde = proc_create_data(minfo->name, 0,
266 (family == NFPROTO_IPV4) ?
267 hashlimit_net->ipt_hashlimit : hashlimit_net->ip6t_hashlimit,
268 &dl_file_ops, hinfo);
269 if (hinfo->pde == NULL) {
270 kfree(hinfo->name);
271 vfree(hinfo);
272 return -ENOMEM;
273 }
274 hinfo->net = net;
275
276 INIT_DEFERRABLE_WORK(&hinfo->gc_work, htable_gc);
277 queue_delayed_work(system_power_efficient_wq, &hinfo->gc_work,
278 msecs_to_jiffies(hinfo->cfg.gc_interval));
279
280 hlist_add_head(&hinfo->node, &hashlimit_net->htables);
281
282 return 0;
283 }
284
285 static bool select_all(const struct xt_hashlimit_htable *ht,
286 const struct dsthash_ent *he)
287 {
288 return 1;
289 }
290
291 static bool select_gc(const struct xt_hashlimit_htable *ht,
292 const struct dsthash_ent *he)
293 {
294 return time_after_eq(jiffies, he->expires);
295 }
296
297 static void htable_selective_cleanup(struct xt_hashlimit_htable *ht,
298 bool (*select)(const struct xt_hashlimit_htable *ht,
299 const struct dsthash_ent *he))
300 {
301 unsigned int i;
302
303 for (i = 0; i < ht->cfg.size; i++) {
304 struct dsthash_ent *dh;
305 struct hlist_node *n;
306
307 spin_lock_bh(&ht->lock);
308 hlist_for_each_entry_safe(dh, n, &ht->hash[i], node) {
309 if ((*select)(ht, dh))
310 dsthash_free(ht, dh);
311 }
312 spin_unlock_bh(&ht->lock);
313 cond_resched();
314 }
315 }
316
317 static void htable_gc(struct work_struct *work)
318 {
319 struct xt_hashlimit_htable *ht;
320
321 ht = container_of(work, struct xt_hashlimit_htable, gc_work.work);
322
323 htable_selective_cleanup(ht, select_gc);
324
325 queue_delayed_work(system_power_efficient_wq,
326 &ht->gc_work, msecs_to_jiffies(ht->cfg.gc_interval));
327 }
328
329 static void htable_remove_proc_entry(struct xt_hashlimit_htable *hinfo)
330 {
331 struct hashlimit_net *hashlimit_net = hashlimit_pernet(hinfo->net);
332 struct proc_dir_entry *parent;
333
334 if (hinfo->family == NFPROTO_IPV4)
335 parent = hashlimit_net->ipt_hashlimit;
336 else
337 parent = hashlimit_net->ip6t_hashlimit;
338
339 if (parent != NULL)
340 remove_proc_entry(hinfo->name, parent);
341 }
342
343 static void htable_destroy(struct xt_hashlimit_htable *hinfo)
344 {
345 cancel_delayed_work_sync(&hinfo->gc_work);
346 htable_remove_proc_entry(hinfo);
347 htable_selective_cleanup(hinfo, select_all);
348 kfree(hinfo->name);
349 vfree(hinfo);
350 }
351
352 static struct xt_hashlimit_htable *htable_find_get(struct net *net,
353 const char *name,
354 u_int8_t family)
355 {
356 struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
357 struct xt_hashlimit_htable *hinfo;
358
359 hlist_for_each_entry(hinfo, &hashlimit_net->htables, node) {
360 if (!strcmp(name, hinfo->name) &&
361 hinfo->family == family) {
362 hinfo->use++;
363 return hinfo;
364 }
365 }
366 return NULL;
367 }
368
369 static void htable_put(struct xt_hashlimit_htable *hinfo)
370 {
371 mutex_lock(&hashlimit_mutex);
372 if (--hinfo->use == 0) {
373 hlist_del(&hinfo->node);
374 htable_destroy(hinfo);
375 }
376 mutex_unlock(&hashlimit_mutex);
377 }
378
379 /* The algorithm used is the Simple Token Bucket Filter (TBF)
380 * see net/sched/sch_tbf.c in the linux source tree
381 */
382
383 /* Rusty: This is my (non-mathematically-inclined) understanding of
384 this algorithm. The `average rate' in jiffies becomes your initial
385 amount of credit `credit' and the most credit you can ever have
386 `credit_cap'. The `peak rate' becomes the cost of passing the
387 test, `cost'.
388
389 `prev' tracks the last packet hit: you gain one credit per jiffy.
390 If you get credit balance more than this, the extra credit is
391 discarded. Every time the match passes, you lose `cost' credits;
392 if you don't have that many, the test fails.
393
394 See Alexey's formal explanation in net/sched/sch_tbf.c.
395
396 To get the maximum range, we multiply by this factor (ie. you get N
397 credits per jiffy). We want to allow a rate as low as 1 per day
398 (slowest userspace tool allows), which means
399 CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
400 */
401 #define MAX_CPJ (0xFFFFFFFF / (HZ*60*60*24))
402
403 /* Repeated shift and or gives us all 1s, final shift and add 1 gives
404 * us the power of 2 below the theoretical max, so GCC simply does a
405 * shift. */
406 #define _POW2_BELOW2(x) ((x)|((x)>>1))
407 #define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
408 #define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
409 #define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
410 #define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
411 #define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
412
413 #define CREDITS_PER_JIFFY POW2_BELOW32(MAX_CPJ)
414
415 /* in byte mode, the lowest possible rate is one packet/second.
416 * credit_cap is used as a counter that tells us how many times we can
417 * refill the "credits available" counter when it becomes empty.
418 */
419 #define MAX_CPJ_BYTES (0xFFFFFFFF / HZ)
420 #define CREDITS_PER_JIFFY_BYTES POW2_BELOW32(MAX_CPJ_BYTES)
421
422 static u32 xt_hashlimit_len_to_chunks(u32 len)
423 {
424 return (len >> XT_HASHLIMIT_BYTE_SHIFT) + 1;
425 }
426
427 /* Precision saver. */
428 static u32 user2credits(u32 user)
429 {
430 /* If multiplying would overflow... */
431 if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY))
432 /* Divide first. */
433 return (user / XT_HASHLIMIT_SCALE) * HZ * CREDITS_PER_JIFFY;
434
435 return (user * HZ * CREDITS_PER_JIFFY) / XT_HASHLIMIT_SCALE;
436 }
437
438 static u32 user2credits_byte(u32 user)
439 {
440 u64 us = user;
441 us *= HZ * CREDITS_PER_JIFFY_BYTES;
442 return (u32) (us >> 32);
443 }
444
445 static void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now, u32 mode)
446 {
447 unsigned long delta = now - dh->rateinfo.prev;
448 u32 cap;
449
450 if (delta == 0)
451 return;
452
453 dh->rateinfo.prev = now;
454
455 if (mode & XT_HASHLIMIT_BYTES) {
456 u32 tmp = dh->rateinfo.credit;
457 dh->rateinfo.credit += CREDITS_PER_JIFFY_BYTES * delta;
458 cap = CREDITS_PER_JIFFY_BYTES * HZ;
459 if (tmp >= dh->rateinfo.credit) {/* overflow */
460 dh->rateinfo.credit = cap;
461 return;
462 }
463 } else {
464 dh->rateinfo.credit += delta * CREDITS_PER_JIFFY;
465 cap = dh->rateinfo.credit_cap;
466 }
467 if (dh->rateinfo.credit > cap)
468 dh->rateinfo.credit = cap;
469 }
470
471 static void rateinfo_init(struct dsthash_ent *dh,
472 struct xt_hashlimit_htable *hinfo)
473 {
474 dh->rateinfo.prev = jiffies;
475 if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) {
476 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
477 dh->rateinfo.cost = user2credits_byte(hinfo->cfg.avg);
478 dh->rateinfo.credit_cap = hinfo->cfg.burst;
479 } else {
480 dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
481 hinfo->cfg.burst);
482 dh->rateinfo.cost = user2credits(hinfo->cfg.avg);
483 dh->rateinfo.credit_cap = dh->rateinfo.credit;
484 }
485 }
486
487 static inline __be32 maskl(__be32 a, unsigned int l)
488 {
489 return l ? htonl(ntohl(a) & ~0 << (32 - l)) : 0;
490 }
491
492 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
493 static void hashlimit_ipv6_mask(__be32 *i, unsigned int p)
494 {
495 switch (p) {
496 case 0 ... 31:
497 i[0] = maskl(i[0], p);
498 i[1] = i[2] = i[3] = 0;
499 break;
500 case 32 ... 63:
501 i[1] = maskl(i[1], p - 32);
502 i[2] = i[3] = 0;
503 break;
504 case 64 ... 95:
505 i[2] = maskl(i[2], p - 64);
506 i[3] = 0;
507 break;
508 case 96 ... 127:
509 i[3] = maskl(i[3], p - 96);
510 break;
511 case 128:
512 break;
513 }
514 }
515 #endif
516
517 static int
518 hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
519 struct dsthash_dst *dst,
520 const struct sk_buff *skb, unsigned int protoff)
521 {
522 __be16 _ports[2], *ports;
523 u8 nexthdr;
524 int poff;
525
526 memset(dst, 0, sizeof(*dst));
527
528 switch (hinfo->family) {
529 case NFPROTO_IPV4:
530 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
531 dst->ip.dst = maskl(ip_hdr(skb)->daddr,
532 hinfo->cfg.dstmask);
533 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
534 dst->ip.src = maskl(ip_hdr(skb)->saddr,
535 hinfo->cfg.srcmask);
536
537 if (!(hinfo->cfg.mode &
538 (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
539 return 0;
540 nexthdr = ip_hdr(skb)->protocol;
541 break;
542 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
543 case NFPROTO_IPV6:
544 {
545 __be16 frag_off;
546
547 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) {
548 memcpy(&dst->ip6.dst, &ipv6_hdr(skb)->daddr,
549 sizeof(dst->ip6.dst));
550 hashlimit_ipv6_mask(dst->ip6.dst, hinfo->cfg.dstmask);
551 }
552 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) {
553 memcpy(&dst->ip6.src, &ipv6_hdr(skb)->saddr,
554 sizeof(dst->ip6.src));
555 hashlimit_ipv6_mask(dst->ip6.src, hinfo->cfg.srcmask);
556 }
557
558 if (!(hinfo->cfg.mode &
559 (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
560 return 0;
561 nexthdr = ipv6_hdr(skb)->nexthdr;
562 protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, &frag_off);
563 if ((int)protoff < 0)
564 return -1;
565 break;
566 }
567 #endif
568 default:
569 BUG();
570 return 0;
571 }
572
573 poff = proto_ports_offset(nexthdr);
574 if (poff >= 0) {
575 ports = skb_header_pointer(skb, protoff + poff, sizeof(_ports),
576 &_ports);
577 } else {
578 _ports[0] = _ports[1] = 0;
579 ports = _ports;
580 }
581 if (!ports)
582 return -1;
583 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT)
584 dst->src_port = ports[0];
585 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT)
586 dst->dst_port = ports[1];
587 return 0;
588 }
589
590 static u32 hashlimit_byte_cost(unsigned int len, struct dsthash_ent *dh)
591 {
592 u64 tmp = xt_hashlimit_len_to_chunks(len);
593 tmp = tmp * dh->rateinfo.cost;
594
595 if (unlikely(tmp > CREDITS_PER_JIFFY_BYTES * HZ))
596 tmp = CREDITS_PER_JIFFY_BYTES * HZ;
597
598 if (dh->rateinfo.credit < tmp && dh->rateinfo.credit_cap) {
599 dh->rateinfo.credit_cap--;
600 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
601 }
602 return (u32) tmp;
603 }
604
605 static bool
606 hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par)
607 {
608 const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
609 struct xt_hashlimit_htable *hinfo = info->hinfo;
610 unsigned long now = jiffies;
611 struct dsthash_ent *dh;
612 struct dsthash_dst dst;
613 bool race = false;
614 u32 cost;
615
616 if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0)
617 goto hotdrop;
618
619 rcu_read_lock_bh();
620 dh = dsthash_find(hinfo, &dst);
621 if (dh == NULL) {
622 dh = dsthash_alloc_init(hinfo, &dst, &race);
623 if (dh == NULL) {
624 rcu_read_unlock_bh();
625 goto hotdrop;
626 } else if (race) {
627 /* Already got an entry, update expiration timeout */
628 dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
629 rateinfo_recalc(dh, now, hinfo->cfg.mode);
630 } else {
631 dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
632 rateinfo_init(dh, hinfo);
633 }
634 } else {
635 /* update expiration timeout */
636 dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
637 rateinfo_recalc(dh, now, hinfo->cfg.mode);
638 }
639
640 if (info->cfg.mode & XT_HASHLIMIT_BYTES)
641 cost = hashlimit_byte_cost(skb->len, dh);
642 else
643 cost = dh->rateinfo.cost;
644
645 if (dh->rateinfo.credit >= cost) {
646 /* below the limit */
647 dh->rateinfo.credit -= cost;
648 spin_unlock(&dh->lock);
649 rcu_read_unlock_bh();
650 return !(info->cfg.mode & XT_HASHLIMIT_INVERT);
651 }
652
653 spin_unlock(&dh->lock);
654 rcu_read_unlock_bh();
655 /* default match is underlimit - so over the limit, we need to invert */
656 return info->cfg.mode & XT_HASHLIMIT_INVERT;
657
658 hotdrop:
659 par->hotdrop = true;
660 return false;
661 }
662
663 static int hashlimit_mt_check(const struct xt_mtchk_param *par)
664 {
665 struct net *net = par->net;
666 struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
667 int ret;
668
669 if (info->cfg.gc_interval == 0 || info->cfg.expire == 0)
670 return -EINVAL;
671 if (info->name[sizeof(info->name)-1] != '\0')
672 return -EINVAL;
673 if (par->family == NFPROTO_IPV4) {
674 if (info->cfg.srcmask > 32 || info->cfg.dstmask > 32)
675 return -EINVAL;
676 } else {
677 if (info->cfg.srcmask > 128 || info->cfg.dstmask > 128)
678 return -EINVAL;
679 }
680
681 if (info->cfg.mode & ~XT_HASHLIMIT_ALL) {
682 pr_info("Unknown mode mask %X, kernel too old?\n",
683 info->cfg.mode);
684 return -EINVAL;
685 }
686
687 /* Check for overflow. */
688 if (info->cfg.mode & XT_HASHLIMIT_BYTES) {
689 if (user2credits_byte(info->cfg.avg) == 0) {
690 pr_info("overflow, rate too high: %u\n", info->cfg.avg);
691 return -EINVAL;
692 }
693 } else if (info->cfg.burst == 0 ||
694 user2credits(info->cfg.avg * info->cfg.burst) <
695 user2credits(info->cfg.avg)) {
696 pr_info("overflow, try lower: %u/%u\n",
697 info->cfg.avg, info->cfg.burst);
698 return -ERANGE;
699 }
700
701 mutex_lock(&hashlimit_mutex);
702 info->hinfo = htable_find_get(net, info->name, par->family);
703 if (info->hinfo == NULL) {
704 ret = htable_create(net, info, par->family);
705 if (ret < 0) {
706 mutex_unlock(&hashlimit_mutex);
707 return ret;
708 }
709 }
710 mutex_unlock(&hashlimit_mutex);
711 return 0;
712 }
713
714 static void hashlimit_mt_destroy(const struct xt_mtdtor_param *par)
715 {
716 const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
717
718 htable_put(info->hinfo);
719 }
720
721 static struct xt_match hashlimit_mt_reg[] __read_mostly = {
722 {
723 .name = "hashlimit",
724 .revision = 1,
725 .family = NFPROTO_IPV4,
726 .match = hashlimit_mt,
727 .matchsize = sizeof(struct xt_hashlimit_mtinfo1),
728 .checkentry = hashlimit_mt_check,
729 .destroy = hashlimit_mt_destroy,
730 .me = THIS_MODULE,
731 },
732 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
733 {
734 .name = "hashlimit",
735 .revision = 1,
736 .family = NFPROTO_IPV6,
737 .match = hashlimit_mt,
738 .matchsize = sizeof(struct xt_hashlimit_mtinfo1),
739 .checkentry = hashlimit_mt_check,
740 .destroy = hashlimit_mt_destroy,
741 .me = THIS_MODULE,
742 },
743 #endif
744 };
745
746 /* PROC stuff */
747 static void *dl_seq_start(struct seq_file *s, loff_t *pos)
748 __acquires(htable->lock)
749 {
750 struct xt_hashlimit_htable *htable = s->private;
751 unsigned int *bucket;
752
753 spin_lock_bh(&htable->lock);
754 if (*pos >= htable->cfg.size)
755 return NULL;
756
757 bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
758 if (!bucket)
759 return ERR_PTR(-ENOMEM);
760
761 *bucket = *pos;
762 return bucket;
763 }
764
765 static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
766 {
767 struct xt_hashlimit_htable *htable = s->private;
768 unsigned int *bucket = (unsigned int *)v;
769
770 *pos = ++(*bucket);
771 if (*pos >= htable->cfg.size) {
772 kfree(v);
773 return NULL;
774 }
775 return bucket;
776 }
777
778 static void dl_seq_stop(struct seq_file *s, void *v)
779 __releases(htable->lock)
780 {
781 struct xt_hashlimit_htable *htable = s->private;
782 unsigned int *bucket = (unsigned int *)v;
783
784 if (!IS_ERR(bucket))
785 kfree(bucket);
786 spin_unlock_bh(&htable->lock);
787 }
788
789 static int dl_seq_real_show(struct dsthash_ent *ent, u_int8_t family,
790 struct seq_file *s)
791 {
792 const struct xt_hashlimit_htable *ht = s->private;
793
794 spin_lock(&ent->lock);
795 /* recalculate to show accurate numbers */
796 rateinfo_recalc(ent, jiffies, ht->cfg.mode);
797
798 switch (family) {
799 case NFPROTO_IPV4:
800 seq_printf(s, "%ld %pI4:%u->%pI4:%u %u %u %u\n",
801 (long)(ent->expires - jiffies)/HZ,
802 &ent->dst.ip.src,
803 ntohs(ent->dst.src_port),
804 &ent->dst.ip.dst,
805 ntohs(ent->dst.dst_port),
806 ent->rateinfo.credit, ent->rateinfo.credit_cap,
807 ent->rateinfo.cost);
808 break;
809 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
810 case NFPROTO_IPV6:
811 seq_printf(s, "%ld %pI6:%u->%pI6:%u %u %u %u\n",
812 (long)(ent->expires - jiffies)/HZ,
813 &ent->dst.ip6.src,
814 ntohs(ent->dst.src_port),
815 &ent->dst.ip6.dst,
816 ntohs(ent->dst.dst_port),
817 ent->rateinfo.credit, ent->rateinfo.credit_cap,
818 ent->rateinfo.cost);
819 break;
820 #endif
821 default:
822 BUG();
823 }
824 spin_unlock(&ent->lock);
825 return seq_has_overflowed(s);
826 }
827
828 static int dl_seq_show(struct seq_file *s, void *v)
829 {
830 struct xt_hashlimit_htable *htable = s->private;
831 unsigned int *bucket = (unsigned int *)v;
832 struct dsthash_ent *ent;
833
834 if (!hlist_empty(&htable->hash[*bucket])) {
835 hlist_for_each_entry(ent, &htable->hash[*bucket], node)
836 if (dl_seq_real_show(ent, htable->family, s))
837 return -1;
838 }
839 return 0;
840 }
841
842 static const struct seq_operations dl_seq_ops = {
843 .start = dl_seq_start,
844 .next = dl_seq_next,
845 .stop = dl_seq_stop,
846 .show = dl_seq_show
847 };
848
849 static int dl_proc_open(struct inode *inode, struct file *file)
850 {
851 int ret = seq_open(file, &dl_seq_ops);
852
853 if (!ret) {
854 struct seq_file *sf = file->private_data;
855 sf->private = PDE_DATA(inode);
856 }
857 return ret;
858 }
859
860 static const struct file_operations dl_file_ops = {
861 .owner = THIS_MODULE,
862 .open = dl_proc_open,
863 .read = seq_read,
864 .llseek = seq_lseek,
865 .release = seq_release
866 };
867
868 static int __net_init hashlimit_proc_net_init(struct net *net)
869 {
870 struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
871
872 hashlimit_net->ipt_hashlimit = proc_mkdir("ipt_hashlimit", net->proc_net);
873 if (!hashlimit_net->ipt_hashlimit)
874 return -ENOMEM;
875 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
876 hashlimit_net->ip6t_hashlimit = proc_mkdir("ip6t_hashlimit", net->proc_net);
877 if (!hashlimit_net->ip6t_hashlimit) {
878 remove_proc_entry("ipt_hashlimit", net->proc_net);
879 return -ENOMEM;
880 }
881 #endif
882 return 0;
883 }
884
885 static void __net_exit hashlimit_proc_net_exit(struct net *net)
886 {
887 struct xt_hashlimit_htable *hinfo;
888 struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
889
890 /* hashlimit_net_exit() is called before hashlimit_mt_destroy().
891 * Make sure that the parent ipt_hashlimit and ip6t_hashlimit proc
892 * entries is empty before trying to remove it.
893 */
894 mutex_lock(&hashlimit_mutex);
895 hlist_for_each_entry(hinfo, &hashlimit_net->htables, node)
896 htable_remove_proc_entry(hinfo);
897 hashlimit_net->ipt_hashlimit = NULL;
898 hashlimit_net->ip6t_hashlimit = NULL;
899 mutex_unlock(&hashlimit_mutex);
900
901 remove_proc_entry("ipt_hashlimit", net->proc_net);
902 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
903 remove_proc_entry("ip6t_hashlimit", net->proc_net);
904 #endif
905 }
906
907 static int __net_init hashlimit_net_init(struct net *net)
908 {
909 struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
910
911 INIT_HLIST_HEAD(&hashlimit_net->htables);
912 return hashlimit_proc_net_init(net);
913 }
914
915 static void __net_exit hashlimit_net_exit(struct net *net)
916 {
917 hashlimit_proc_net_exit(net);
918 }
919
920 static struct pernet_operations hashlimit_net_ops = {
921 .init = hashlimit_net_init,
922 .exit = hashlimit_net_exit,
923 .id = &hashlimit_net_id,
924 .size = sizeof(struct hashlimit_net),
925 };
926
927 static int __init hashlimit_mt_init(void)
928 {
929 int err;
930
931 err = register_pernet_subsys(&hashlimit_net_ops);
932 if (err < 0)
933 return err;
934 err = xt_register_matches(hashlimit_mt_reg,
935 ARRAY_SIZE(hashlimit_mt_reg));
936 if (err < 0)
937 goto err1;
938
939 err = -ENOMEM;
940 hashlimit_cachep = kmem_cache_create("xt_hashlimit",
941 sizeof(struct dsthash_ent), 0, 0,
942 NULL);
943 if (!hashlimit_cachep) {
944 pr_warn("unable to create slab cache\n");
945 goto err2;
946 }
947 return 0;
948
949 err2:
950 xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
951 err1:
952 unregister_pernet_subsys(&hashlimit_net_ops);
953 return err;
954
955 }
956
957 static void __exit hashlimit_mt_exit(void)
958 {
959 xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
960 unregister_pernet_subsys(&hashlimit_net_ops);
961
962 rcu_barrier_bh();
963 kmem_cache_destroy(hashlimit_cachep);
964 }
965
966 module_init(hashlimit_mt_init);
967 module_exit(hashlimit_mt_exit);
Linux kernel - Deliverables
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