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Linux/net/netfilter/xt_hashlimit.c

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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  *      (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 #include <linux/kernel.h>
 39 
 40 MODULE_LICENSE("GPL");
 41 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
 42 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
 43 MODULE_DESCRIPTION("Xtables: per hash-bucket rate-limit match");
 44 MODULE_ALIAS("ipt_hashlimit");
 45 MODULE_ALIAS("ip6t_hashlimit");
 46 
 47 struct hashlimit_net {
 48         struct hlist_head       htables;
 49         struct proc_dir_entry   *ipt_hashlimit;
 50         struct proc_dir_entry   *ip6t_hashlimit;
 51 };
 52 
 53 static unsigned int hashlimit_net_id;
 54 static inline struct hashlimit_net *hashlimit_pernet(struct net *net)
 55 {
 56         return net_generic(net, hashlimit_net_id);
 57 }
 58 
 59 /* need to declare this at the top */
 60 static const struct seq_operations dl_seq_ops_v2;
 61 static const struct seq_operations dl_seq_ops_v1;
 62 static const struct seq_operations dl_seq_ops;
 63 
 64 /* hash table crap */
 65 struct dsthash_dst {
 66         union {
 67                 struct {
 68                         __be32 src;
 69                         __be32 dst;
 70                 } ip;
 71 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 72                 struct {
 73                         __be32 src[4];
 74                         __be32 dst[4];
 75                 } ip6;
 76 #endif
 77         };
 78         __be16 src_port;
 79         __be16 dst_port;
 80 };
 81 
 82 struct dsthash_ent {
 83         /* static / read-only parts in the beginning */
 84         struct hlist_node node;
 85         struct dsthash_dst dst;
 86 
 87         /* modified structure members in the end */
 88         spinlock_t lock;
 89         unsigned long expires;          /* precalculated expiry time */
 90         struct {
 91                 unsigned long prev;     /* last modification */
 92                 union {
 93                         struct {
 94                                 u_int64_t credit;
 95                                 u_int64_t credit_cap;
 96                                 u_int64_t cost;
 97                         };
 98                         struct {
 99                                 u_int32_t interval, prev_window;
100                                 u_int64_t current_rate;
101                                 u_int64_t rate;
102                                 int64_t burst;
103                         };
104                 };
105         } rateinfo;
106         struct rcu_head rcu;
107 };
108 
109 struct xt_hashlimit_htable {
110         struct hlist_node node;         /* global list of all htables */
111         int use;
112         u_int8_t family;
113         bool rnd_initialized;
114 
115         struct hashlimit_cfg3 cfg;      /* config */
116 
117         /* used internally */
118         spinlock_t lock;                /* lock for list_head */
119         u_int32_t rnd;                  /* random seed for hash */
120         unsigned int count;             /* number entries in table */
121         struct delayed_work gc_work;
122 
123         /* seq_file stuff */
124         struct proc_dir_entry *pde;
125         const char *name;
126         struct net *net;
127 
128         struct hlist_head hash[0];      /* hashtable itself */
129 };
130 
131 static int
132 cfg_copy(struct hashlimit_cfg3 *to, const void *from, int revision)
133 {
134         if (revision == 1) {
135                 struct hashlimit_cfg1 *cfg = (struct hashlimit_cfg1 *)from;
136 
137                 to->mode = cfg->mode;
138                 to->avg = cfg->avg;
139                 to->burst = cfg->burst;
140                 to->size = cfg->size;
141                 to->max = cfg->max;
142                 to->gc_interval = cfg->gc_interval;
143                 to->expire = cfg->expire;
144                 to->srcmask = cfg->srcmask;
145                 to->dstmask = cfg->dstmask;
146         } else if (revision == 2) {
147                 struct hashlimit_cfg2 *cfg = (struct hashlimit_cfg2 *)from;
148 
149                 to->mode = cfg->mode;
150                 to->avg = cfg->avg;
151                 to->burst = cfg->burst;
152                 to->size = cfg->size;
153                 to->max = cfg->max;
154                 to->gc_interval = cfg->gc_interval;
155                 to->expire = cfg->expire;
156                 to->srcmask = cfg->srcmask;
157                 to->dstmask = cfg->dstmask;
158         } else if (revision == 3) {
159                 memcpy(to, from, sizeof(struct hashlimit_cfg3));
160         } else {
161                 return -EINVAL;
162         }
163 
164         return 0;
165 }
166 
167 static DEFINE_MUTEX(hashlimit_mutex);   /* protects htables list */
168 static struct kmem_cache *hashlimit_cachep __read_mostly;
169 
170 static inline bool dst_cmp(const struct dsthash_ent *ent,
171                            const struct dsthash_dst *b)
172 {
173         return !memcmp(&ent->dst, b, sizeof(ent->dst));
174 }
175 
176 static u_int32_t
177 hash_dst(const struct xt_hashlimit_htable *ht, const struct dsthash_dst *dst)
178 {
179         u_int32_t hash = jhash2((const u32 *)dst,
180                                 sizeof(*dst)/sizeof(u32),
181                                 ht->rnd);
182         /*
183          * Instead of returning hash % ht->cfg.size (implying a divide)
184          * we return the high 32 bits of the (hash * ht->cfg.size) that will
185          * give results between [0 and cfg.size-1] and same hash distribution,
186          * but using a multiply, less expensive than a divide
187          */
188         return reciprocal_scale(hash, ht->cfg.size);
189 }
190 
191 static struct dsthash_ent *
192 dsthash_find(const struct xt_hashlimit_htable *ht,
193              const struct dsthash_dst *dst)
194 {
195         struct dsthash_ent *ent;
196         u_int32_t hash = hash_dst(ht, dst);
197 
198         if (!hlist_empty(&ht->hash[hash])) {
199                 hlist_for_each_entry_rcu(ent, &ht->hash[hash], node)
200                         if (dst_cmp(ent, dst)) {
201                                 spin_lock(&ent->lock);
202                                 return ent;
203                         }
204         }
205         return NULL;
206 }
207 
208 /* allocate dsthash_ent, initialize dst, put in htable and lock it */
209 static struct dsthash_ent *
210 dsthash_alloc_init(struct xt_hashlimit_htable *ht,
211                    const struct dsthash_dst *dst, bool *race)
212 {
213         struct dsthash_ent *ent;
214 
215         spin_lock(&ht->lock);
216 
217         /* Two or more packets may race to create the same entry in the
218          * hashtable, double check if this packet lost race.
219          */
220         ent = dsthash_find(ht, dst);
221         if (ent != NULL) {
222                 spin_unlock(&ht->lock);
223                 *race = true;
224                 return ent;
225         }
226 
227         /* initialize hash with random val at the time we allocate
228          * the first hashtable entry */
229         if (unlikely(!ht->rnd_initialized)) {
230                 get_random_bytes(&ht->rnd, sizeof(ht->rnd));
231                 ht->rnd_initialized = true;
232         }
233 
234         if (ht->cfg.max && ht->count >= ht->cfg.max) {
235                 /* FIXME: do something. question is what.. */
236                 net_err_ratelimited("max count of %u reached\n", ht->cfg.max);
237                 ent = NULL;
238         } else
239                 ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
240         if (ent) {
241                 memcpy(&ent->dst, dst, sizeof(ent->dst));
242                 spin_lock_init(&ent->lock);
243 
244                 spin_lock(&ent->lock);
245                 hlist_add_head_rcu(&ent->node, &ht->hash[hash_dst(ht, dst)]);
246                 ht->count++;
247         }
248         spin_unlock(&ht->lock);
249         return ent;
250 }
251 
252 static void dsthash_free_rcu(struct rcu_head *head)
253 {
254         struct dsthash_ent *ent = container_of(head, struct dsthash_ent, rcu);
255 
256         kmem_cache_free(hashlimit_cachep, ent);
257 }
258 
259 static inline void
260 dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent)
261 {
262         hlist_del_rcu(&ent->node);
263         call_rcu(&ent->rcu, dsthash_free_rcu);
264         ht->count--;
265 }
266 static void htable_gc(struct work_struct *work);
267 
268 static int htable_create(struct net *net, struct hashlimit_cfg3 *cfg,
269                          const char *name, u_int8_t family,
270                          struct xt_hashlimit_htable **out_hinfo,
271                          int revision)
272 {
273         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
274         struct xt_hashlimit_htable *hinfo;
275         const struct seq_operations *ops;
276         unsigned int size, i;
277         unsigned long nr_pages = totalram_pages();
278         int ret;
279 
280         if (cfg->size) {
281                 size = cfg->size;
282         } else {
283                 size = (nr_pages << PAGE_SHIFT) / 16384 /
284                        sizeof(struct hlist_head);
285                 if (nr_pages > 1024 * 1024 * 1024 / PAGE_SIZE)
286                         size = 8192;
287                 if (size < 16)
288                         size = 16;
289         }
290         /* FIXME: don't use vmalloc() here or anywhere else -HW */
291         hinfo = vmalloc(sizeof(struct xt_hashlimit_htable) +
292                         sizeof(struct hlist_head) * size);
293         if (hinfo == NULL)
294                 return -ENOMEM;
295         *out_hinfo = hinfo;
296 
297         /* copy match config into hashtable config */
298         ret = cfg_copy(&hinfo->cfg, (void *)cfg, 3);
299         if (ret) {
300                 vfree(hinfo);
301                 return ret;
302         }
303 
304         hinfo->cfg.size = size;
305         if (hinfo->cfg.max == 0)
306                 hinfo->cfg.max = 8 * hinfo->cfg.size;
307         else if (hinfo->cfg.max < hinfo->cfg.size)
308                 hinfo->cfg.max = hinfo->cfg.size;
309 
310         for (i = 0; i < hinfo->cfg.size; i++)
311                 INIT_HLIST_HEAD(&hinfo->hash[i]);
312 
313         hinfo->use = 1;
314         hinfo->count = 0;
315         hinfo->family = family;
316         hinfo->rnd_initialized = false;
317         hinfo->name = kstrdup(name, GFP_KERNEL);
318         if (!hinfo->name) {
319                 vfree(hinfo);
320                 return -ENOMEM;
321         }
322         spin_lock_init(&hinfo->lock);
323 
324         switch (revision) {
325         case 1:
326                 ops = &dl_seq_ops_v1;
327                 break;
328         case 2:
329                 ops = &dl_seq_ops_v2;
330                 break;
331         default:
332                 ops = &dl_seq_ops;
333         }
334 
335         hinfo->pde = proc_create_seq_data(name, 0,
336                 (family == NFPROTO_IPV4) ?
337                 hashlimit_net->ipt_hashlimit : hashlimit_net->ip6t_hashlimit,
338                 ops, hinfo);
339         if (hinfo->pde == NULL) {
340                 kfree(hinfo->name);
341                 vfree(hinfo);
342                 return -ENOMEM;
343         }
344         hinfo->net = net;
345 
346         INIT_DEFERRABLE_WORK(&hinfo->gc_work, htable_gc);
347         queue_delayed_work(system_power_efficient_wq, &hinfo->gc_work,
348                            msecs_to_jiffies(hinfo->cfg.gc_interval));
349 
350         hlist_add_head(&hinfo->node, &hashlimit_net->htables);
351 
352         return 0;
353 }
354 
355 static bool select_all(const struct xt_hashlimit_htable *ht,
356                        const struct dsthash_ent *he)
357 {
358         return true;
359 }
360 
361 static bool select_gc(const struct xt_hashlimit_htable *ht,
362                       const struct dsthash_ent *he)
363 {
364         return time_after_eq(jiffies, he->expires);
365 }
366 
367 static void htable_selective_cleanup(struct xt_hashlimit_htable *ht,
368                         bool (*select)(const struct xt_hashlimit_htable *ht,
369                                       const struct dsthash_ent *he))
370 {
371         unsigned int i;
372 
373         for (i = 0; i < ht->cfg.size; i++) {
374                 struct dsthash_ent *dh;
375                 struct hlist_node *n;
376 
377                 spin_lock_bh(&ht->lock);
378                 hlist_for_each_entry_safe(dh, n, &ht->hash[i], node) {
379                         if ((*select)(ht, dh))
380                                 dsthash_free(ht, dh);
381                 }
382                 spin_unlock_bh(&ht->lock);
383                 cond_resched();
384         }
385 }
386 
387 static void htable_gc(struct work_struct *work)
388 {
389         struct xt_hashlimit_htable *ht;
390 
391         ht = container_of(work, struct xt_hashlimit_htable, gc_work.work);
392 
393         htable_selective_cleanup(ht, select_gc);
394 
395         queue_delayed_work(system_power_efficient_wq,
396                            &ht->gc_work, msecs_to_jiffies(ht->cfg.gc_interval));
397 }
398 
399 static void htable_remove_proc_entry(struct xt_hashlimit_htable *hinfo)
400 {
401         struct hashlimit_net *hashlimit_net = hashlimit_pernet(hinfo->net);
402         struct proc_dir_entry *parent;
403 
404         if (hinfo->family == NFPROTO_IPV4)
405                 parent = hashlimit_net->ipt_hashlimit;
406         else
407                 parent = hashlimit_net->ip6t_hashlimit;
408 
409         if (parent != NULL)
410                 remove_proc_entry(hinfo->name, parent);
411 }
412 
413 static void htable_destroy(struct xt_hashlimit_htable *hinfo)
414 {
415         cancel_delayed_work_sync(&hinfo->gc_work);
416         htable_remove_proc_entry(hinfo);
417         htable_selective_cleanup(hinfo, select_all);
418         kfree(hinfo->name);
419         vfree(hinfo);
420 }
421 
422 static struct xt_hashlimit_htable *htable_find_get(struct net *net,
423                                                    const char *name,
424                                                    u_int8_t family)
425 {
426         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
427         struct xt_hashlimit_htable *hinfo;
428 
429         hlist_for_each_entry(hinfo, &hashlimit_net->htables, node) {
430                 if (!strcmp(name, hinfo->name) &&
431                     hinfo->family == family) {
432                         hinfo->use++;
433                         return hinfo;
434                 }
435         }
436         return NULL;
437 }
438 
439 static void htable_put(struct xt_hashlimit_htable *hinfo)
440 {
441         mutex_lock(&hashlimit_mutex);
442         if (--hinfo->use == 0) {
443                 hlist_del(&hinfo->node);
444                 htable_destroy(hinfo);
445         }
446         mutex_unlock(&hashlimit_mutex);
447 }
448 
449 /* The algorithm used is the Simple Token Bucket Filter (TBF)
450  * see net/sched/sch_tbf.c in the linux source tree
451  */
452 
453 /* Rusty: This is my (non-mathematically-inclined) understanding of
454    this algorithm.  The `average rate' in jiffies becomes your initial
455    amount of credit `credit' and the most credit you can ever have
456    `credit_cap'.  The `peak rate' becomes the cost of passing the
457    test, `cost'.
458 
459    `prev' tracks the last packet hit: you gain one credit per jiffy.
460    If you get credit balance more than this, the extra credit is
461    discarded.  Every time the match passes, you lose `cost' credits;
462    if you don't have that many, the test fails.
463 
464    See Alexey's formal explanation in net/sched/sch_tbf.c.
465 
466    To get the maximum range, we multiply by this factor (ie. you get N
467    credits per jiffy).  We want to allow a rate as low as 1 per day
468    (slowest userspace tool allows), which means
469    CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
470 */
471 #define MAX_CPJ_v1 (0xFFFFFFFF / (HZ*60*60*24))
472 #define MAX_CPJ (0xFFFFFFFFFFFFFFFFULL / (HZ*60*60*24))
473 
474 /* Repeated shift and or gives us all 1s, final shift and add 1 gives
475  * us the power of 2 below the theoretical max, so GCC simply does a
476  * shift. */
477 #define _POW2_BELOW2(x) ((x)|((x)>>1))
478 #define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
479 #define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
480 #define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
481 #define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
482 #define _POW2_BELOW64(x) (_POW2_BELOW32(x)|_POW2_BELOW32((x)>>32))
483 #define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
484 #define POW2_BELOW64(x) ((_POW2_BELOW64(x)>>1) + 1)
485 
486 #define CREDITS_PER_JIFFY POW2_BELOW64(MAX_CPJ)
487 #define CREDITS_PER_JIFFY_v1 POW2_BELOW32(MAX_CPJ_v1)
488 
489 /* in byte mode, the lowest possible rate is one packet/second.
490  * credit_cap is used as a counter that tells us how many times we can
491  * refill the "credits available" counter when it becomes empty.
492  */
493 #define MAX_CPJ_BYTES (0xFFFFFFFF / HZ)
494 #define CREDITS_PER_JIFFY_BYTES POW2_BELOW32(MAX_CPJ_BYTES)
495 
496 static u32 xt_hashlimit_len_to_chunks(u32 len)
497 {
498         return (len >> XT_HASHLIMIT_BYTE_SHIFT) + 1;
499 }
500 
501 /* Precision saver. */
502 static u64 user2credits(u64 user, int revision)
503 {
504         u64 scale = (revision == 1) ?
505                 XT_HASHLIMIT_SCALE : XT_HASHLIMIT_SCALE_v2;
506         u64 cpj = (revision == 1) ?
507                 CREDITS_PER_JIFFY_v1 : CREDITS_PER_JIFFY;
508 
509         /* Avoid overflow: divide the constant operands first */
510         if (scale >= HZ * cpj)
511                 return div64_u64(user, div64_u64(scale, HZ * cpj));
512 
513         return user * div64_u64(HZ * cpj, scale);
514 }
515 
516 static u32 user2credits_byte(u32 user)
517 {
518         u64 us = user;
519         us *= HZ * CREDITS_PER_JIFFY_BYTES;
520         return (u32) (us >> 32);
521 }
522 
523 static u64 user2rate(u64 user)
524 {
525         if (user != 0) {
526                 return div64_u64(XT_HASHLIMIT_SCALE_v2, user);
527         } else {
528                 pr_info_ratelimited("invalid rate from userspace: %llu\n",
529                                     user);
530                 return 0;
531         }
532 }
533 
534 static u64 user2rate_bytes(u32 user)
535 {
536         u64 r;
537 
538         r = user ? U32_MAX / user : U32_MAX;
539         return (r - 1) << XT_HASHLIMIT_BYTE_SHIFT;
540 }
541 
542 static void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now,
543                             u32 mode, int revision)
544 {
545         unsigned long delta = now - dh->rateinfo.prev;
546         u64 cap, cpj;
547 
548         if (delta == 0)
549                 return;
550 
551         if (revision >= 3 && mode & XT_HASHLIMIT_RATE_MATCH) {
552                 u64 interval = dh->rateinfo.interval * HZ;
553 
554                 if (delta < interval)
555                         return;
556 
557                 dh->rateinfo.prev = now;
558                 dh->rateinfo.prev_window =
559                         ((dh->rateinfo.current_rate * interval) >
560                          (delta * dh->rateinfo.rate));
561                 dh->rateinfo.current_rate = 0;
562 
563                 return;
564         }
565 
566         dh->rateinfo.prev = now;
567 
568         if (mode & XT_HASHLIMIT_BYTES) {
569                 u64 tmp = dh->rateinfo.credit;
570                 dh->rateinfo.credit += CREDITS_PER_JIFFY_BYTES * delta;
571                 cap = CREDITS_PER_JIFFY_BYTES * HZ;
572                 if (tmp >= dh->rateinfo.credit) {/* overflow */
573                         dh->rateinfo.credit = cap;
574                         return;
575                 }
576         } else {
577                 cpj = (revision == 1) ?
578                         CREDITS_PER_JIFFY_v1 : CREDITS_PER_JIFFY;
579                 dh->rateinfo.credit += delta * cpj;
580                 cap = dh->rateinfo.credit_cap;
581         }
582         if (dh->rateinfo.credit > cap)
583                 dh->rateinfo.credit = cap;
584 }
585 
586 static void rateinfo_init(struct dsthash_ent *dh,
587                           struct xt_hashlimit_htable *hinfo, int revision)
588 {
589         dh->rateinfo.prev = jiffies;
590         if (revision >= 3 && hinfo->cfg.mode & XT_HASHLIMIT_RATE_MATCH) {
591                 dh->rateinfo.prev_window = 0;
592                 dh->rateinfo.current_rate = 0;
593                 if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) {
594                         dh->rateinfo.rate =
595                                 user2rate_bytes((u32)hinfo->cfg.avg);
596                         if (hinfo->cfg.burst)
597                                 dh->rateinfo.burst =
598                                         hinfo->cfg.burst * dh->rateinfo.rate;
599                         else
600                                 dh->rateinfo.burst = dh->rateinfo.rate;
601                 } else {
602                         dh->rateinfo.rate = user2rate(hinfo->cfg.avg);
603                         dh->rateinfo.burst =
604                                 hinfo->cfg.burst + dh->rateinfo.rate;
605                 }
606                 dh->rateinfo.interval = hinfo->cfg.interval;
607         } else if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) {
608                 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
609                 dh->rateinfo.cost = user2credits_byte(hinfo->cfg.avg);
610                 dh->rateinfo.credit_cap = hinfo->cfg.burst;
611         } else {
612                 dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
613                                                    hinfo->cfg.burst, revision);
614                 dh->rateinfo.cost = user2credits(hinfo->cfg.avg, revision);
615                 dh->rateinfo.credit_cap = dh->rateinfo.credit;
616         }
617 }
618 
619 static inline __be32 maskl(__be32 a, unsigned int l)
620 {
621         return l ? htonl(ntohl(a) & ~0 << (32 - l)) : 0;
622 }
623 
624 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
625 static void hashlimit_ipv6_mask(__be32 *i, unsigned int p)
626 {
627         switch (p) {
628         case 0 ... 31:
629                 i[0] = maskl(i[0], p);
630                 i[1] = i[2] = i[3] = 0;
631                 break;
632         case 32 ... 63:
633                 i[1] = maskl(i[1], p - 32);
634                 i[2] = i[3] = 0;
635                 break;
636         case 64 ... 95:
637                 i[2] = maskl(i[2], p - 64);
638                 i[3] = 0;
639                 break;
640         case 96 ... 127:
641                 i[3] = maskl(i[3], p - 96);
642                 break;
643         case 128:
644                 break;
645         }
646 }
647 #endif
648 
649 static int
650 hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
651                    struct dsthash_dst *dst,
652                    const struct sk_buff *skb, unsigned int protoff)
653 {
654         __be16 _ports[2], *ports;
655         u8 nexthdr;
656         int poff;
657 
658         memset(dst, 0, sizeof(*dst));
659 
660         switch (hinfo->family) {
661         case NFPROTO_IPV4:
662                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
663                         dst->ip.dst = maskl(ip_hdr(skb)->daddr,
664                                       hinfo->cfg.dstmask);
665                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
666                         dst->ip.src = maskl(ip_hdr(skb)->saddr,
667                                       hinfo->cfg.srcmask);
668 
669                 if (!(hinfo->cfg.mode &
670                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
671                         return 0;
672                 nexthdr = ip_hdr(skb)->protocol;
673                 break;
674 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
675         case NFPROTO_IPV6:
676         {
677                 __be16 frag_off;
678 
679                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) {
680                         memcpy(&dst->ip6.dst, &ipv6_hdr(skb)->daddr,
681                                sizeof(dst->ip6.dst));
682                         hashlimit_ipv6_mask(dst->ip6.dst, hinfo->cfg.dstmask);
683                 }
684                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) {
685                         memcpy(&dst->ip6.src, &ipv6_hdr(skb)->saddr,
686                                sizeof(dst->ip6.src));
687                         hashlimit_ipv6_mask(dst->ip6.src, hinfo->cfg.srcmask);
688                 }
689 
690                 if (!(hinfo->cfg.mode &
691                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
692                         return 0;
693                 nexthdr = ipv6_hdr(skb)->nexthdr;
694                 protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, &frag_off);
695                 if ((int)protoff < 0)
696                         return -1;
697                 break;
698         }
699 #endif
700         default:
701                 BUG();
702                 return 0;
703         }
704 
705         poff = proto_ports_offset(nexthdr);
706         if (poff >= 0) {
707                 ports = skb_header_pointer(skb, protoff + poff, sizeof(_ports),
708                                            &_ports);
709         } else {
710                 _ports[0] = _ports[1] = 0;
711                 ports = _ports;
712         }
713         if (!ports)
714                 return -1;
715         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT)
716                 dst->src_port = ports[0];
717         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT)
718                 dst->dst_port = ports[1];
719         return 0;
720 }
721 
722 static u32 hashlimit_byte_cost(unsigned int len, struct dsthash_ent *dh)
723 {
724         u64 tmp = xt_hashlimit_len_to_chunks(len);
725         tmp = tmp * dh->rateinfo.cost;
726 
727         if (unlikely(tmp > CREDITS_PER_JIFFY_BYTES * HZ))
728                 tmp = CREDITS_PER_JIFFY_BYTES * HZ;
729 
730         if (dh->rateinfo.credit < tmp && dh->rateinfo.credit_cap) {
731                 dh->rateinfo.credit_cap--;
732                 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
733         }
734         return (u32) tmp;
735 }
736 
737 static bool
738 hashlimit_mt_common(const struct sk_buff *skb, struct xt_action_param *par,
739                     struct xt_hashlimit_htable *hinfo,
740                     const struct hashlimit_cfg3 *cfg, int revision)
741 {
742         unsigned long now = jiffies;
743         struct dsthash_ent *dh;
744         struct dsthash_dst dst;
745         bool race = false;
746         u64 cost;
747 
748         if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0)
749                 goto hotdrop;
750 
751         local_bh_disable();
752         dh = dsthash_find(hinfo, &dst);
753         if (dh == NULL) {
754                 dh = dsthash_alloc_init(hinfo, &dst, &race);
755                 if (dh == NULL) {
756                         local_bh_enable();
757                         goto hotdrop;
758                 } else if (race) {
759                         /* Already got an entry, update expiration timeout */
760                         dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
761                         rateinfo_recalc(dh, now, hinfo->cfg.mode, revision);
762                 } else {
763                         dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
764                         rateinfo_init(dh, hinfo, revision);
765                 }
766         } else {
767                 /* update expiration timeout */
768                 dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
769                 rateinfo_recalc(dh, now, hinfo->cfg.mode, revision);
770         }
771 
772         if (cfg->mode & XT_HASHLIMIT_RATE_MATCH) {
773                 cost = (cfg->mode & XT_HASHLIMIT_BYTES) ? skb->len : 1;
774                 dh->rateinfo.current_rate += cost;
775 
776                 if (!dh->rateinfo.prev_window &&
777                     (dh->rateinfo.current_rate <= dh->rateinfo.burst)) {
778                         spin_unlock(&dh->lock);
779                         local_bh_enable();
780                         return !(cfg->mode & XT_HASHLIMIT_INVERT);
781                 } else {
782                         goto overlimit;
783                 }
784         }
785 
786         if (cfg->mode & XT_HASHLIMIT_BYTES)
787                 cost = hashlimit_byte_cost(skb->len, dh);
788         else
789                 cost = dh->rateinfo.cost;
790 
791         if (dh->rateinfo.credit >= cost) {
792                 /* below the limit */
793                 dh->rateinfo.credit -= cost;
794                 spin_unlock(&dh->lock);
795                 local_bh_enable();
796                 return !(cfg->mode & XT_HASHLIMIT_INVERT);
797         }
798 
799 overlimit:
800         spin_unlock(&dh->lock);
801         local_bh_enable();
802         /* default match is underlimit - so over the limit, we need to invert */
803         return cfg->mode & XT_HASHLIMIT_INVERT;
804 
805  hotdrop:
806         par->hotdrop = true;
807         return false;
808 }
809 
810 static bool
811 hashlimit_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
812 {
813         const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
814         struct xt_hashlimit_htable *hinfo = info->hinfo;
815         struct hashlimit_cfg3 cfg = {};
816         int ret;
817 
818         ret = cfg_copy(&cfg, (void *)&info->cfg, 1);
819         if (ret)
820                 return ret;
821 
822         return hashlimit_mt_common(skb, par, hinfo, &cfg, 1);
823 }
824 
825 static bool
826 hashlimit_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
827 {
828         const struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
829         struct xt_hashlimit_htable *hinfo = info->hinfo;
830         struct hashlimit_cfg3 cfg = {};
831         int ret;
832 
833         ret = cfg_copy(&cfg, (void *)&info->cfg, 2);
834         if (ret)
835                 return ret;
836 
837         return hashlimit_mt_common(skb, par, hinfo, &cfg, 2);
838 }
839 
840 static bool
841 hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par)
842 {
843         const struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
844         struct xt_hashlimit_htable *hinfo = info->hinfo;
845 
846         return hashlimit_mt_common(skb, par, hinfo, &info->cfg, 3);
847 }
848 
849 static int hashlimit_mt_check_common(const struct xt_mtchk_param *par,
850                                      struct xt_hashlimit_htable **hinfo,
851                                      struct hashlimit_cfg3 *cfg,
852                                      const char *name, int revision)
853 {
854         struct net *net = par->net;
855         int ret;
856 
857         if (cfg->gc_interval == 0 || cfg->expire == 0)
858                 return -EINVAL;
859         if (par->family == NFPROTO_IPV4) {
860                 if (cfg->srcmask > 32 || cfg->dstmask > 32)
861                         return -EINVAL;
862         } else {
863                 if (cfg->srcmask > 128 || cfg->dstmask > 128)
864                         return -EINVAL;
865         }
866 
867         if (cfg->mode & ~XT_HASHLIMIT_ALL) {
868                 pr_info_ratelimited("Unknown mode mask %X, kernel too old?\n",
869                                     cfg->mode);
870                 return -EINVAL;
871         }
872 
873         /* Check for overflow. */
874         if (revision >= 3 && cfg->mode & XT_HASHLIMIT_RATE_MATCH) {
875                 if (cfg->avg == 0 || cfg->avg > U32_MAX) {
876                         pr_info_ratelimited("invalid rate\n");
877                         return -ERANGE;
878                 }
879 
880                 if (cfg->interval == 0) {
881                         pr_info_ratelimited("invalid interval\n");
882                         return -EINVAL;
883                 }
884         } else if (cfg->mode & XT_HASHLIMIT_BYTES) {
885                 if (user2credits_byte(cfg->avg) == 0) {
886                         pr_info_ratelimited("overflow, rate too high: %llu\n",
887                                             cfg->avg);
888                         return -EINVAL;
889                 }
890         } else if (cfg->burst == 0 ||
891                    user2credits(cfg->avg * cfg->burst, revision) <
892                    user2credits(cfg->avg, revision)) {
893                 pr_info_ratelimited("overflow, try lower: %llu/%llu\n",
894                                     cfg->avg, cfg->burst);
895                 return -ERANGE;
896         }
897 
898         mutex_lock(&hashlimit_mutex);
899         *hinfo = htable_find_get(net, name, par->family);
900         if (*hinfo == NULL) {
901                 ret = htable_create(net, cfg, name, par->family,
902                                     hinfo, revision);
903                 if (ret < 0) {
904                         mutex_unlock(&hashlimit_mutex);
905                         return ret;
906                 }
907         }
908         mutex_unlock(&hashlimit_mutex);
909 
910         return 0;
911 }
912 
913 static int hashlimit_mt_check_v1(const struct xt_mtchk_param *par)
914 {
915         struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
916         struct hashlimit_cfg3 cfg = {};
917         int ret;
918 
919         ret = xt_check_proc_name(info->name, sizeof(info->name));
920         if (ret)
921                 return ret;
922 
923         ret = cfg_copy(&cfg, (void *)&info->cfg, 1);
924         if (ret)
925                 return ret;
926 
927         return hashlimit_mt_check_common(par, &info->hinfo,
928                                          &cfg, info->name, 1);
929 }
930 
931 static int hashlimit_mt_check_v2(const struct xt_mtchk_param *par)
932 {
933         struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
934         struct hashlimit_cfg3 cfg = {};
935         int ret;
936 
937         ret = xt_check_proc_name(info->name, sizeof(info->name));
938         if (ret)
939                 return ret;
940 
941         ret = cfg_copy(&cfg, (void *)&info->cfg, 2);
942         if (ret)
943                 return ret;
944 
945         return hashlimit_mt_check_common(par, &info->hinfo,
946                                          &cfg, info->name, 2);
947 }
948 
949 static int hashlimit_mt_check(const struct xt_mtchk_param *par)
950 {
951         struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
952         int ret;
953 
954         ret = xt_check_proc_name(info->name, sizeof(info->name));
955         if (ret)
956                 return ret;
957 
958         return hashlimit_mt_check_common(par, &info->hinfo, &info->cfg,
959                                          info->name, 3);
960 }
961 
962 static void hashlimit_mt_destroy_v2(const struct xt_mtdtor_param *par)
963 {
964         const struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
965 
966         htable_put(info->hinfo);
967 }
968 
969 static void hashlimit_mt_destroy_v1(const struct xt_mtdtor_param *par)
970 {
971         const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
972 
973         htable_put(info->hinfo);
974 }
975 
976 static void hashlimit_mt_destroy(const struct xt_mtdtor_param *par)
977 {
978         const struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
979 
980         htable_put(info->hinfo);
981 }
982 
983 static struct xt_match hashlimit_mt_reg[] __read_mostly = {
984         {
985                 .name           = "hashlimit",
986                 .revision       = 1,
987                 .family         = NFPROTO_IPV4,
988                 .match          = hashlimit_mt_v1,
989                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
990                 .usersize       = offsetof(struct xt_hashlimit_mtinfo1, hinfo),
991                 .checkentry     = hashlimit_mt_check_v1,
992                 .destroy        = hashlimit_mt_destroy_v1,
993                 .me             = THIS_MODULE,
994         },
995         {
996                 .name           = "hashlimit",
997                 .revision       = 2,
998                 .family         = NFPROTO_IPV4,
999                 .match          = hashlimit_mt_v2,
1000                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo2),
1001                 .usersize       = offsetof(struct xt_hashlimit_mtinfo2, hinfo),
1002                 .checkentry     = hashlimit_mt_check_v2,
1003                 .destroy        = hashlimit_mt_destroy_v2,
1004                 .me             = THIS_MODULE,
1005         },
1006         {
1007                 .name           = "hashlimit",
1008                 .revision       = 3,
1009                 .family         = NFPROTO_IPV4,
1010                 .match          = hashlimit_mt,
1011                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo3),
1012                 .usersize       = offsetof(struct xt_hashlimit_mtinfo3, hinfo),
1013                 .checkentry     = hashlimit_mt_check,
1014                 .destroy        = hashlimit_mt_destroy,
1015                 .me             = THIS_MODULE,
1016         },
1017 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1018         {
1019                 .name           = "hashlimit",
1020                 .revision       = 1,
1021                 .family         = NFPROTO_IPV6,
1022                 .match          = hashlimit_mt_v1,
1023                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
1024                 .usersize       = offsetof(struct xt_hashlimit_mtinfo1, hinfo),
1025                 .checkentry     = hashlimit_mt_check_v1,
1026                 .destroy        = hashlimit_mt_destroy_v1,
1027                 .me             = THIS_MODULE,
1028         },
1029         {
1030                 .name           = "hashlimit",
1031                 .revision       = 2,
1032                 .family         = NFPROTO_IPV6,
1033                 .match          = hashlimit_mt_v2,
1034                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo2),
1035                 .usersize       = offsetof(struct xt_hashlimit_mtinfo2, hinfo),
1036                 .checkentry     = hashlimit_mt_check_v2,
1037                 .destroy        = hashlimit_mt_destroy_v2,
1038                 .me             = THIS_MODULE,
1039         },
1040         {
1041                 .name           = "hashlimit",
1042                 .revision       = 3,
1043                 .family         = NFPROTO_IPV6,
1044                 .match          = hashlimit_mt,
1045                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo3),
1046                 .usersize       = offsetof(struct xt_hashlimit_mtinfo3, hinfo),
1047                 .checkentry     = hashlimit_mt_check,
1048                 .destroy        = hashlimit_mt_destroy,
1049                 .me             = THIS_MODULE,
1050         },
1051 #endif
1052 };
1053 
1054 /* PROC stuff */
1055 static void *dl_seq_start(struct seq_file *s, loff_t *pos)
1056         __acquires(htable->lock)
1057 {
1058         struct xt_hashlimit_htable *htable = PDE_DATA(file_inode(s->file));
1059         unsigned int *bucket;
1060 
1061         spin_lock_bh(&htable->lock);
1062         if (*pos >= htable->cfg.size)
1063                 return NULL;
1064 
1065         bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
1066         if (!bucket)
1067                 return ERR_PTR(-ENOMEM);
1068 
1069         *bucket = *pos;
1070         return bucket;
1071 }
1072 
1073 static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
1074 {
1075         struct xt_hashlimit_htable *htable = PDE_DATA(file_inode(s->file));
1076         unsigned int *bucket = v;
1077 
1078         *pos = ++(*bucket);
1079         if (*pos >= htable->cfg.size) {
1080                 kfree(v);
1081                 return NULL;
1082         }
1083         return bucket;
1084 }
1085 
1086 static void dl_seq_stop(struct seq_file *s, void *v)
1087         __releases(htable->lock)
1088 {
1089         struct xt_hashlimit_htable *htable = PDE_DATA(file_inode(s->file));
1090         unsigned int *bucket = v;
1091 
1092         if (!IS_ERR(bucket))
1093                 kfree(bucket);
1094         spin_unlock_bh(&htable->lock);
1095 }
1096 
1097 static void dl_seq_print(struct dsthash_ent *ent, u_int8_t family,
1098                          struct seq_file *s)
1099 {
1100         switch (family) {
1101         case NFPROTO_IPV4:
1102                 seq_printf(s, "%ld %pI4:%u->%pI4:%u %llu %llu %llu\n",
1103                            (long)(ent->expires - jiffies)/HZ,
1104                            &ent->dst.ip.src,
1105                            ntohs(ent->dst.src_port),
1106                            &ent->dst.ip.dst,
1107                            ntohs(ent->dst.dst_port),
1108                            ent->rateinfo.credit, ent->rateinfo.credit_cap,
1109                            ent->rateinfo.cost);
1110                 break;
1111 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1112         case NFPROTO_IPV6:
1113                 seq_printf(s, "%ld %pI6:%u->%pI6:%u %llu %llu %llu\n",
1114                            (long)(ent->expires - jiffies)/HZ,
1115                            &ent->dst.ip6.src,
1116                            ntohs(ent->dst.src_port),
1117                            &ent->dst.ip6.dst,
1118                            ntohs(ent->dst.dst_port),
1119                            ent->rateinfo.credit, ent->rateinfo.credit_cap,
1120                            ent->rateinfo.cost);
1121                 break;
1122 #endif
1123         default:
1124                 BUG();
1125         }
1126 }
1127 
1128 static int dl_seq_real_show_v2(struct dsthash_ent *ent, u_int8_t family,
1129                                struct seq_file *s)
1130 {
1131         struct xt_hashlimit_htable *ht = PDE_DATA(file_inode(s->file));
1132 
1133         spin_lock(&ent->lock);
1134         /* recalculate to show accurate numbers */
1135         rateinfo_recalc(ent, jiffies, ht->cfg.mode, 2);
1136 
1137         dl_seq_print(ent, family, s);
1138 
1139         spin_unlock(&ent->lock);
1140         return seq_has_overflowed(s);
1141 }
1142 
1143 static int dl_seq_real_show_v1(struct dsthash_ent *ent, u_int8_t family,
1144                                struct seq_file *s)
1145 {
1146         struct xt_hashlimit_htable *ht = PDE_DATA(file_inode(s->file));
1147 
1148         spin_lock(&ent->lock);
1149         /* recalculate to show accurate numbers */
1150         rateinfo_recalc(ent, jiffies, ht->cfg.mode, 1);
1151 
1152         dl_seq_print(ent, family, s);
1153 
1154         spin_unlock(&ent->lock);
1155         return seq_has_overflowed(s);
1156 }
1157 
1158 static int dl_seq_real_show(struct dsthash_ent *ent, u_int8_t family,
1159                             struct seq_file *s)
1160 {
1161         struct xt_hashlimit_htable *ht = PDE_DATA(file_inode(s->file));
1162 
1163         spin_lock(&ent->lock);
1164         /* recalculate to show accurate numbers */
1165         rateinfo_recalc(ent, jiffies, ht->cfg.mode, 3);
1166 
1167         dl_seq_print(ent, family, s);
1168 
1169         spin_unlock(&ent->lock);
1170         return seq_has_overflowed(s);
1171 }
1172 
1173 static int dl_seq_show_v2(struct seq_file *s, void *v)
1174 {
1175         struct xt_hashlimit_htable *htable = PDE_DATA(file_inode(s->file));
1176         unsigned int *bucket = (unsigned int *)v;
1177         struct dsthash_ent *ent;
1178 
1179         if (!hlist_empty(&htable->hash[*bucket])) {
1180                 hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1181                         if (dl_seq_real_show_v2(ent, htable->family, s))
1182                                 return -1;
1183         }
1184         return 0;
1185 }
1186 
1187 static int dl_seq_show_v1(struct seq_file *s, void *v)
1188 {
1189         struct xt_hashlimit_htable *htable = PDE_DATA(file_inode(s->file));
1190         unsigned int *bucket = v;
1191         struct dsthash_ent *ent;
1192 
1193         if (!hlist_empty(&htable->hash[*bucket])) {
1194                 hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1195                         if (dl_seq_real_show_v1(ent, htable->family, s))
1196                                 return -1;
1197         }
1198         return 0;
1199 }
1200 
1201 static int dl_seq_show(struct seq_file *s, void *v)
1202 {
1203         struct xt_hashlimit_htable *htable = PDE_DATA(file_inode(s->file));
1204         unsigned int *bucket = v;
1205         struct dsthash_ent *ent;
1206 
1207         if (!hlist_empty(&htable->hash[*bucket])) {
1208                 hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1209                         if (dl_seq_real_show(ent, htable->family, s))
1210                                 return -1;
1211         }
1212         return 0;
1213 }
1214 
1215 static const struct seq_operations dl_seq_ops_v1 = {
1216         .start = dl_seq_start,
1217         .next  = dl_seq_next,
1218         .stop  = dl_seq_stop,
1219         .show  = dl_seq_show_v1
1220 };
1221 
1222 static const struct seq_operations dl_seq_ops_v2 = {
1223         .start = dl_seq_start,
1224         .next  = dl_seq_next,
1225         .stop  = dl_seq_stop,
1226         .show  = dl_seq_show_v2
1227 };
1228 
1229 static const struct seq_operations dl_seq_ops = {
1230         .start = dl_seq_start,
1231         .next  = dl_seq_next,
1232         .stop  = dl_seq_stop,
1233         .show  = dl_seq_show
1234 };
1235 
1236 static int __net_init hashlimit_proc_net_init(struct net *net)
1237 {
1238         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1239 
1240         hashlimit_net->ipt_hashlimit = proc_mkdir("ipt_hashlimit", net->proc_net);
1241         if (!hashlimit_net->ipt_hashlimit)
1242                 return -ENOMEM;
1243 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1244         hashlimit_net->ip6t_hashlimit = proc_mkdir("ip6t_hashlimit", net->proc_net);
1245         if (!hashlimit_net->ip6t_hashlimit) {
1246                 remove_proc_entry("ipt_hashlimit", net->proc_net);
1247                 return -ENOMEM;
1248         }
1249 #endif
1250         return 0;
1251 }
1252 
1253 static void __net_exit hashlimit_proc_net_exit(struct net *net)
1254 {
1255         struct xt_hashlimit_htable *hinfo;
1256         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1257 
1258         /* hashlimit_net_exit() is called before hashlimit_mt_destroy().
1259          * Make sure that the parent ipt_hashlimit and ip6t_hashlimit proc
1260          * entries is empty before trying to remove it.
1261          */
1262         mutex_lock(&hashlimit_mutex);
1263         hlist_for_each_entry(hinfo, &hashlimit_net->htables, node)
1264                 htable_remove_proc_entry(hinfo);
1265         hashlimit_net->ipt_hashlimit = NULL;
1266         hashlimit_net->ip6t_hashlimit = NULL;
1267         mutex_unlock(&hashlimit_mutex);
1268 
1269         remove_proc_entry("ipt_hashlimit", net->proc_net);
1270 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1271         remove_proc_entry("ip6t_hashlimit", net->proc_net);
1272 #endif
1273 }
1274 
1275 static int __net_init hashlimit_net_init(struct net *net)
1276 {
1277         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1278 
1279         INIT_HLIST_HEAD(&hashlimit_net->htables);
1280         return hashlimit_proc_net_init(net);
1281 }
1282 
1283 static void __net_exit hashlimit_net_exit(struct net *net)
1284 {
1285         hashlimit_proc_net_exit(net);
1286 }
1287 
1288 static struct pernet_operations hashlimit_net_ops = {
1289         .init   = hashlimit_net_init,
1290         .exit   = hashlimit_net_exit,
1291         .id     = &hashlimit_net_id,
1292         .size   = sizeof(struct hashlimit_net),
1293 };
1294 
1295 static int __init hashlimit_mt_init(void)
1296 {
1297         int err;
1298 
1299         err = register_pernet_subsys(&hashlimit_net_ops);
1300         if (err < 0)
1301                 return err;
1302         err = xt_register_matches(hashlimit_mt_reg,
1303               ARRAY_SIZE(hashlimit_mt_reg));
1304         if (err < 0)
1305                 goto err1;
1306 
1307         err = -ENOMEM;
1308         hashlimit_cachep = kmem_cache_create("xt_hashlimit",
1309                                             sizeof(struct dsthash_ent), 0, 0,
1310                                             NULL);
1311         if (!hashlimit_cachep) {
1312                 pr_warn("unable to create slab cache\n");
1313                 goto err2;
1314         }
1315         return 0;
1316 
1317 err2:
1318         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
1319 err1:
1320         unregister_pernet_subsys(&hashlimit_net_ops);
1321         return err;
1322 
1323 }
1324 
1325 static void __exit hashlimit_mt_exit(void)
1326 {
1327         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
1328         unregister_pernet_subsys(&hashlimit_net_ops);
1329 
1330         rcu_barrier();
1331         kmem_cache_destroy(hashlimit_cachep);
1332 }
1333 
1334 module_init(hashlimit_mt_init);
1335 module_exit(hashlimit_mt_exit);
1336 

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