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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 file_operations dl_file_ops_v2;
 61 static const struct file_operations dl_file_ops_v1;
 62 static const struct file_operations dl_file_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_bh(&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 file_operations *fops;
276         unsigned int size, i;
277         int ret;
278 
279         if (cfg->size) {
280                 size = cfg->size;
281         } else {
282                 size = (totalram_pages << PAGE_SHIFT) / 16384 /
283                        sizeof(struct hlist_head);
284                 if (totalram_pages > 1024 * 1024 * 1024 / PAGE_SIZE)
285                         size = 8192;
286                 if (size < 16)
287                         size = 16;
288         }
289         /* FIXME: don't use vmalloc() here or anywhere else -HW */
290         hinfo = vmalloc(sizeof(struct xt_hashlimit_htable) +
291                         sizeof(struct hlist_head) * size);
292         if (hinfo == NULL)
293                 return -ENOMEM;
294         *out_hinfo = hinfo;
295 
296         /* copy match config into hashtable config */
297         ret = cfg_copy(&hinfo->cfg, (void *)cfg, 3);
298 
299         if (ret)
300                 return ret;
301 
302         hinfo->cfg.size = size;
303         if (hinfo->cfg.max == 0)
304                 hinfo->cfg.max = 8 * hinfo->cfg.size;
305         else if (hinfo->cfg.max < hinfo->cfg.size)
306                 hinfo->cfg.max = hinfo->cfg.size;
307 
308         for (i = 0; i < hinfo->cfg.size; i++)
309                 INIT_HLIST_HEAD(&hinfo->hash[i]);
310 
311         hinfo->use = 1;
312         hinfo->count = 0;
313         hinfo->family = family;
314         hinfo->rnd_initialized = false;
315         hinfo->name = kstrdup(name, GFP_KERNEL);
316         if (!hinfo->name) {
317                 vfree(hinfo);
318                 return -ENOMEM;
319         }
320         spin_lock_init(&hinfo->lock);
321 
322         switch (revision) {
323         case 1:
324                 fops = &dl_file_ops_v1;
325                 break;
326         case 2:
327                 fops = &dl_file_ops_v2;
328                 break;
329         default:
330                 fops = &dl_file_ops;
331         }
332 
333         hinfo->pde = proc_create_data(name, 0,
334                 (family == NFPROTO_IPV4) ?
335                 hashlimit_net->ipt_hashlimit : hashlimit_net->ip6t_hashlimit,
336                 fops, hinfo);
337         if (hinfo->pde == NULL) {
338                 kfree(hinfo->name);
339                 vfree(hinfo);
340                 return -ENOMEM;
341         }
342         hinfo->net = net;
343 
344         INIT_DEFERRABLE_WORK(&hinfo->gc_work, htable_gc);
345         queue_delayed_work(system_power_efficient_wq, &hinfo->gc_work,
346                            msecs_to_jiffies(hinfo->cfg.gc_interval));
347 
348         hlist_add_head(&hinfo->node, &hashlimit_net->htables);
349 
350         return 0;
351 }
352 
353 static bool select_all(const struct xt_hashlimit_htable *ht,
354                        const struct dsthash_ent *he)
355 {
356         return 1;
357 }
358 
359 static bool select_gc(const struct xt_hashlimit_htable *ht,
360                       const struct dsthash_ent *he)
361 {
362         return time_after_eq(jiffies, he->expires);
363 }
364 
365 static void htable_selective_cleanup(struct xt_hashlimit_htable *ht,
366                         bool (*select)(const struct xt_hashlimit_htable *ht,
367                                       const struct dsthash_ent *he))
368 {
369         unsigned int i;
370 
371         for (i = 0; i < ht->cfg.size; i++) {
372                 struct dsthash_ent *dh;
373                 struct hlist_node *n;
374 
375                 spin_lock_bh(&ht->lock);
376                 hlist_for_each_entry_safe(dh, n, &ht->hash[i], node) {
377                         if ((*select)(ht, dh))
378                                 dsthash_free(ht, dh);
379                 }
380                 spin_unlock_bh(&ht->lock);
381                 cond_resched();
382         }
383 }
384 
385 static void htable_gc(struct work_struct *work)
386 {
387         struct xt_hashlimit_htable *ht;
388 
389         ht = container_of(work, struct xt_hashlimit_htable, gc_work.work);
390 
391         htable_selective_cleanup(ht, select_gc);
392 
393         queue_delayed_work(system_power_efficient_wq,
394                            &ht->gc_work, msecs_to_jiffies(ht->cfg.gc_interval));
395 }
396 
397 static void htable_remove_proc_entry(struct xt_hashlimit_htable *hinfo)
398 {
399         struct hashlimit_net *hashlimit_net = hashlimit_pernet(hinfo->net);
400         struct proc_dir_entry *parent;
401 
402         if (hinfo->family == NFPROTO_IPV4)
403                 parent = hashlimit_net->ipt_hashlimit;
404         else
405                 parent = hashlimit_net->ip6t_hashlimit;
406 
407         if (parent != NULL)
408                 remove_proc_entry(hinfo->name, parent);
409 }
410 
411 static void htable_destroy(struct xt_hashlimit_htable *hinfo)
412 {
413         cancel_delayed_work_sync(&hinfo->gc_work);
414         htable_remove_proc_entry(hinfo);
415         htable_selective_cleanup(hinfo, select_all);
416         kfree(hinfo->name);
417         vfree(hinfo);
418 }
419 
420 static struct xt_hashlimit_htable *htable_find_get(struct net *net,
421                                                    const char *name,
422                                                    u_int8_t family)
423 {
424         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
425         struct xt_hashlimit_htable *hinfo;
426 
427         hlist_for_each_entry(hinfo, &hashlimit_net->htables, node) {
428                 if (!strcmp(name, hinfo->name) &&
429                     hinfo->family == family) {
430                         hinfo->use++;
431                         return hinfo;
432                 }
433         }
434         return NULL;
435 }
436 
437 static void htable_put(struct xt_hashlimit_htable *hinfo)
438 {
439         mutex_lock(&hashlimit_mutex);
440         if (--hinfo->use == 0) {
441                 hlist_del(&hinfo->node);
442                 htable_destroy(hinfo);
443         }
444         mutex_unlock(&hashlimit_mutex);
445 }
446 
447 /* The algorithm used is the Simple Token Bucket Filter (TBF)
448  * see net/sched/sch_tbf.c in the linux source tree
449  */
450 
451 /* Rusty: This is my (non-mathematically-inclined) understanding of
452    this algorithm.  The `average rate' in jiffies becomes your initial
453    amount of credit `credit' and the most credit you can ever have
454    `credit_cap'.  The `peak rate' becomes the cost of passing the
455    test, `cost'.
456 
457    `prev' tracks the last packet hit: you gain one credit per jiffy.
458    If you get credit balance more than this, the extra credit is
459    discarded.  Every time the match passes, you lose `cost' credits;
460    if you don't have that many, the test fails.
461 
462    See Alexey's formal explanation in net/sched/sch_tbf.c.
463 
464    To get the maximum range, we multiply by this factor (ie. you get N
465    credits per jiffy).  We want to allow a rate as low as 1 per day
466    (slowest userspace tool allows), which means
467    CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
468 */
469 #define MAX_CPJ_v1 (0xFFFFFFFF / (HZ*60*60*24))
470 #define MAX_CPJ (0xFFFFFFFFFFFFFFFFULL / (HZ*60*60*24))
471 
472 /* Repeated shift and or gives us all 1s, final shift and add 1 gives
473  * us the power of 2 below the theoretical max, so GCC simply does a
474  * shift. */
475 #define _POW2_BELOW2(x) ((x)|((x)>>1))
476 #define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
477 #define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
478 #define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
479 #define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
480 #define _POW2_BELOW64(x) (_POW2_BELOW32(x)|_POW2_BELOW32((x)>>32))
481 #define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
482 #define POW2_BELOW64(x) ((_POW2_BELOW64(x)>>1) + 1)
483 
484 #define CREDITS_PER_JIFFY POW2_BELOW64(MAX_CPJ)
485 #define CREDITS_PER_JIFFY_v1 POW2_BELOW32(MAX_CPJ_v1)
486 
487 /* in byte mode, the lowest possible rate is one packet/second.
488  * credit_cap is used as a counter that tells us how many times we can
489  * refill the "credits available" counter when it becomes empty.
490  */
491 #define MAX_CPJ_BYTES (0xFFFFFFFF / HZ)
492 #define CREDITS_PER_JIFFY_BYTES POW2_BELOW32(MAX_CPJ_BYTES)
493 
494 static u32 xt_hashlimit_len_to_chunks(u32 len)
495 {
496         return (len >> XT_HASHLIMIT_BYTE_SHIFT) + 1;
497 }
498 
499 /* Precision saver. */
500 static u64 user2credits(u64 user, int revision)
501 {
502         u64 scale = (revision == 1) ?
503                 XT_HASHLIMIT_SCALE : XT_HASHLIMIT_SCALE_v2;
504         u64 cpj = (revision == 1) ?
505                 CREDITS_PER_JIFFY_v1 : CREDITS_PER_JIFFY;
506 
507         /* Avoid overflow: divide the constant operands first */
508         if (scale >= HZ * cpj)
509                 return div64_u64(user, div64_u64(scale, HZ * cpj));
510 
511         return user * div64_u64(HZ * cpj, scale);
512 }
513 
514 static u32 user2credits_byte(u32 user)
515 {
516         u64 us = user;
517         us *= HZ * CREDITS_PER_JIFFY_BYTES;
518         return (u32) (us >> 32);
519 }
520 
521 static u64 user2rate(u64 user)
522 {
523         if (user != 0) {
524                 return div64_u64(XT_HASHLIMIT_SCALE_v2, user);
525         } else {
526                 pr_warn("invalid rate from userspace: %llu\n", user);
527                 return 0;
528         }
529 }
530 
531 static u64 user2rate_bytes(u32 user)
532 {
533         u64 r;
534 
535         r = user ? U32_MAX / user : U32_MAX;
536         r = (r - 1) << XT_HASHLIMIT_BYTE_SHIFT;
537         return r;
538 }
539 
540 static void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now,
541                             u32 mode, int revision)
542 {
543         unsigned long delta = now - dh->rateinfo.prev;
544         u64 cap, cpj;
545 
546         if (delta == 0)
547                 return;
548 
549         if (revision >= 3 && mode & XT_HASHLIMIT_RATE_MATCH) {
550                 u64 interval = dh->rateinfo.interval * HZ;
551 
552                 if (delta < interval)
553                         return;
554 
555                 dh->rateinfo.prev = now;
556                 dh->rateinfo.prev_window =
557                         ((dh->rateinfo.current_rate * interval) >
558                          (delta * dh->rateinfo.rate));
559                 dh->rateinfo.current_rate = 0;
560 
561                 return;
562         }
563 
564         dh->rateinfo.prev = now;
565 
566         if (mode & XT_HASHLIMIT_BYTES) {
567                 u64 tmp = dh->rateinfo.credit;
568                 dh->rateinfo.credit += CREDITS_PER_JIFFY_BYTES * delta;
569                 cap = CREDITS_PER_JIFFY_BYTES * HZ;
570                 if (tmp >= dh->rateinfo.credit) {/* overflow */
571                         dh->rateinfo.credit = cap;
572                         return;
573                 }
574         } else {
575                 cpj = (revision == 1) ?
576                         CREDITS_PER_JIFFY_v1 : CREDITS_PER_JIFFY;
577                 dh->rateinfo.credit += delta * cpj;
578                 cap = dh->rateinfo.credit_cap;
579         }
580         if (dh->rateinfo.credit > cap)
581                 dh->rateinfo.credit = cap;
582 }
583 
584 static void rateinfo_init(struct dsthash_ent *dh,
585                           struct xt_hashlimit_htable *hinfo, int revision)
586 {
587         dh->rateinfo.prev = jiffies;
588         if (revision >= 3 && hinfo->cfg.mode & XT_HASHLIMIT_RATE_MATCH) {
589                 dh->rateinfo.prev_window = 0;
590                 dh->rateinfo.current_rate = 0;
591                 if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) {
592                         dh->rateinfo.rate =
593                                 user2rate_bytes((u32)hinfo->cfg.avg);
594                         if (hinfo->cfg.burst)
595                                 dh->rateinfo.burst =
596                                         hinfo->cfg.burst * dh->rateinfo.rate;
597                         else
598                                 dh->rateinfo.burst = dh->rateinfo.rate;
599                 } else {
600                         dh->rateinfo.rate = user2rate(hinfo->cfg.avg);
601                         dh->rateinfo.burst =
602                                 hinfo->cfg.burst + dh->rateinfo.rate;
603                 }
604                 dh->rateinfo.interval = hinfo->cfg.interval;
605         } else if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) {
606                 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
607                 dh->rateinfo.cost = user2credits_byte(hinfo->cfg.avg);
608                 dh->rateinfo.credit_cap = hinfo->cfg.burst;
609         } else {
610                 dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
611                                                    hinfo->cfg.burst, revision);
612                 dh->rateinfo.cost = user2credits(hinfo->cfg.avg, revision);
613                 dh->rateinfo.credit_cap = dh->rateinfo.credit;
614         }
615 }
616 
617 static inline __be32 maskl(__be32 a, unsigned int l)
618 {
619         return l ? htonl(ntohl(a) & ~0 << (32 - l)) : 0;
620 }
621 
622 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
623 static void hashlimit_ipv6_mask(__be32 *i, unsigned int p)
624 {
625         switch (p) {
626         case 0 ... 31:
627                 i[0] = maskl(i[0], p);
628                 i[1] = i[2] = i[3] = 0;
629                 break;
630         case 32 ... 63:
631                 i[1] = maskl(i[1], p - 32);
632                 i[2] = i[3] = 0;
633                 break;
634         case 64 ... 95:
635                 i[2] = maskl(i[2], p - 64);
636                 i[3] = 0;
637                 break;
638         case 96 ... 127:
639                 i[3] = maskl(i[3], p - 96);
640                 break;
641         case 128:
642                 break;
643         }
644 }
645 #endif
646 
647 static int
648 hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
649                    struct dsthash_dst *dst,
650                    const struct sk_buff *skb, unsigned int protoff)
651 {
652         __be16 _ports[2], *ports;
653         u8 nexthdr;
654         int poff;
655 
656         memset(dst, 0, sizeof(*dst));
657 
658         switch (hinfo->family) {
659         case NFPROTO_IPV4:
660                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
661                         dst->ip.dst = maskl(ip_hdr(skb)->daddr,
662                                       hinfo->cfg.dstmask);
663                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
664                         dst->ip.src = maskl(ip_hdr(skb)->saddr,
665                                       hinfo->cfg.srcmask);
666 
667                 if (!(hinfo->cfg.mode &
668                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
669                         return 0;
670                 nexthdr = ip_hdr(skb)->protocol;
671                 break;
672 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
673         case NFPROTO_IPV6:
674         {
675                 __be16 frag_off;
676 
677                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) {
678                         memcpy(&dst->ip6.dst, &ipv6_hdr(skb)->daddr,
679                                sizeof(dst->ip6.dst));
680                         hashlimit_ipv6_mask(dst->ip6.dst, hinfo->cfg.dstmask);
681                 }
682                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) {
683                         memcpy(&dst->ip6.src, &ipv6_hdr(skb)->saddr,
684                                sizeof(dst->ip6.src));
685                         hashlimit_ipv6_mask(dst->ip6.src, hinfo->cfg.srcmask);
686                 }
687 
688                 if (!(hinfo->cfg.mode &
689                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
690                         return 0;
691                 nexthdr = ipv6_hdr(skb)->nexthdr;
692                 protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, &frag_off);
693                 if ((int)protoff < 0)
694                         return -1;
695                 break;
696         }
697 #endif
698         default:
699                 BUG();
700                 return 0;
701         }
702 
703         poff = proto_ports_offset(nexthdr);
704         if (poff >= 0) {
705                 ports = skb_header_pointer(skb, protoff + poff, sizeof(_ports),
706                                            &_ports);
707         } else {
708                 _ports[0] = _ports[1] = 0;
709                 ports = _ports;
710         }
711         if (!ports)
712                 return -1;
713         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT)
714                 dst->src_port = ports[0];
715         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT)
716                 dst->dst_port = ports[1];
717         return 0;
718 }
719 
720 static u32 hashlimit_byte_cost(unsigned int len, struct dsthash_ent *dh)
721 {
722         u64 tmp = xt_hashlimit_len_to_chunks(len);
723         tmp = tmp * dh->rateinfo.cost;
724 
725         if (unlikely(tmp > CREDITS_PER_JIFFY_BYTES * HZ))
726                 tmp = CREDITS_PER_JIFFY_BYTES * HZ;
727 
728         if (dh->rateinfo.credit < tmp && dh->rateinfo.credit_cap) {
729                 dh->rateinfo.credit_cap--;
730                 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
731         }
732         return (u32) tmp;
733 }
734 
735 static bool
736 hashlimit_mt_common(const struct sk_buff *skb, struct xt_action_param *par,
737                     struct xt_hashlimit_htable *hinfo,
738                     const struct hashlimit_cfg3 *cfg, int revision)
739 {
740         unsigned long now = jiffies;
741         struct dsthash_ent *dh;
742         struct dsthash_dst dst;
743         bool race = false;
744         u64 cost;
745 
746         if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0)
747                 goto hotdrop;
748 
749         local_bh_disable();
750         dh = dsthash_find(hinfo, &dst);
751         if (dh == NULL) {
752                 dh = dsthash_alloc_init(hinfo, &dst, &race);
753                 if (dh == NULL) {
754                         local_bh_enable();
755                         goto hotdrop;
756                 } else if (race) {
757                         /* Already got an entry, update expiration timeout */
758                         dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
759                         rateinfo_recalc(dh, now, hinfo->cfg.mode, revision);
760                 } else {
761                         dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
762                         rateinfo_init(dh, hinfo, revision);
763                 }
764         } else {
765                 /* update expiration timeout */
766                 dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
767                 rateinfo_recalc(dh, now, hinfo->cfg.mode, revision);
768         }
769 
770         if (cfg->mode & XT_HASHLIMIT_RATE_MATCH) {
771                 cost = (cfg->mode & XT_HASHLIMIT_BYTES) ? skb->len : 1;
772                 dh->rateinfo.current_rate += cost;
773 
774                 if (!dh->rateinfo.prev_window &&
775                     (dh->rateinfo.current_rate <= dh->rateinfo.burst)) {
776                         spin_unlock(&dh->lock);
777                         local_bh_enable();
778                         return !(cfg->mode & XT_HASHLIMIT_INVERT);
779                 } else {
780                         goto overlimit;
781                 }
782         }
783 
784         if (cfg->mode & XT_HASHLIMIT_BYTES)
785                 cost = hashlimit_byte_cost(skb->len, dh);
786         else
787                 cost = dh->rateinfo.cost;
788 
789         if (dh->rateinfo.credit >= cost) {
790                 /* below the limit */
791                 dh->rateinfo.credit -= cost;
792                 spin_unlock(&dh->lock);
793                 local_bh_enable();
794                 return !(cfg->mode & XT_HASHLIMIT_INVERT);
795         }
796 
797 overlimit:
798         spin_unlock(&dh->lock);
799         local_bh_enable();
800         /* default match is underlimit - so over the limit, we need to invert */
801         return cfg->mode & XT_HASHLIMIT_INVERT;
802 
803  hotdrop:
804         par->hotdrop = true;
805         return false;
806 }
807 
808 static bool
809 hashlimit_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
810 {
811         const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
812         struct xt_hashlimit_htable *hinfo = info->hinfo;
813         struct hashlimit_cfg3 cfg = {};
814         int ret;
815 
816         ret = cfg_copy(&cfg, (void *)&info->cfg, 1);
817 
818         if (ret)
819                 return ret;
820 
821         return hashlimit_mt_common(skb, par, hinfo, &cfg, 1);
822 }
823 
824 static bool
825 hashlimit_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
826 {
827         const struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
828         struct xt_hashlimit_htable *hinfo = info->hinfo;
829         struct hashlimit_cfg3 cfg = {};
830         int ret;
831 
832         ret = cfg_copy(&cfg, (void *)&info->cfg, 2);
833 
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("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("hashlimit invalid rate\n");
877                         return -ERANGE;
878                 }
879 
880                 if (cfg->interval == 0) {
881                         pr_info("hashlimit 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("overflow, rate too high: %llu\n", cfg->avg);
887                         return -EINVAL;
888                 }
889         } else if (cfg->burst == 0 ||
890                     user2credits(cfg->avg * cfg->burst, revision) <
891                     user2credits(cfg->avg, revision)) {
892                         pr_info("overflow, try lower: %llu/%llu\n",
893                                 cfg->avg, cfg->burst);
894                         return -ERANGE;
895         }
896 
897         mutex_lock(&hashlimit_mutex);
898         *hinfo = htable_find_get(net, name, par->family);
899         if (*hinfo == NULL) {
900                 ret = htable_create(net, cfg, name, par->family,
901                                     hinfo, revision);
902                 if (ret < 0) {
903                         mutex_unlock(&hashlimit_mutex);
904                         return ret;
905                 }
906         }
907         mutex_unlock(&hashlimit_mutex);
908 
909         return 0;
910 }
911 
912 static int hashlimit_mt_check_v1(const struct xt_mtchk_param *par)
913 {
914         struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
915         struct hashlimit_cfg3 cfg = {};
916         int ret;
917 
918         ret = xt_check_proc_name(info->name, sizeof(info->name));
919         if (ret)
920                 return ret;
921 
922         ret = cfg_copy(&cfg, (void *)&info->cfg, 1);
923 
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 
943         if (ret)
944                 return ret;
945 
946         return hashlimit_mt_check_common(par, &info->hinfo,
947                                          &cfg, info->name, 2);
948 }
949 
950 static int hashlimit_mt_check(const struct xt_mtchk_param *par)
951 {
952         struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
953         int ret;
954 
955         ret = xt_check_proc_name(info->name, sizeof(info->name));
956         if (ret)
957                 return ret;
958 
959         return hashlimit_mt_check_common(par, &info->hinfo, &info->cfg,
960                                          info->name, 3);
961 }
962 
963 static void hashlimit_mt_destroy_v2(const struct xt_mtdtor_param *par)
964 {
965         const struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
966 
967         htable_put(info->hinfo);
968 }
969 
970 static void hashlimit_mt_destroy_v1(const struct xt_mtdtor_param *par)
971 {
972         const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
973 
974         htable_put(info->hinfo);
975 }
976 
977 static void hashlimit_mt_destroy(const struct xt_mtdtor_param *par)
978 {
979         const struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
980 
981         htable_put(info->hinfo);
982 }
983 
984 static struct xt_match hashlimit_mt_reg[] __read_mostly = {
985         {
986                 .name           = "hashlimit",
987                 .revision       = 1,
988                 .family         = NFPROTO_IPV4,
989                 .match          = hashlimit_mt_v1,
990                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
991                 .usersize       = offsetof(struct xt_hashlimit_mtinfo1, hinfo),
992                 .checkentry     = hashlimit_mt_check_v1,
993                 .destroy        = hashlimit_mt_destroy_v1,
994                 .me             = THIS_MODULE,
995         },
996         {
997                 .name           = "hashlimit",
998                 .revision       = 2,
999                 .family         = NFPROTO_IPV4,
1000                 .match          = hashlimit_mt_v2,
1001                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo2),
1002                 .usersize       = offsetof(struct xt_hashlimit_mtinfo2, hinfo),
1003                 .checkentry     = hashlimit_mt_check_v2,
1004                 .destroy        = hashlimit_mt_destroy_v2,
1005                 .me             = THIS_MODULE,
1006         },
1007         {
1008                 .name           = "hashlimit",
1009                 .revision       = 3,
1010                 .family         = NFPROTO_IPV4,
1011                 .match          = hashlimit_mt,
1012                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo3),
1013                 .usersize       = offsetof(struct xt_hashlimit_mtinfo3, hinfo),
1014                 .checkentry     = hashlimit_mt_check,
1015                 .destroy        = hashlimit_mt_destroy,
1016                 .me             = THIS_MODULE,
1017         },
1018 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1019         {
1020                 .name           = "hashlimit",
1021                 .revision       = 1,
1022                 .family         = NFPROTO_IPV6,
1023                 .match          = hashlimit_mt_v1,
1024                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
1025                 .usersize       = offsetof(struct xt_hashlimit_mtinfo1, hinfo),
1026                 .checkentry     = hashlimit_mt_check_v1,
1027                 .destroy        = hashlimit_mt_destroy_v1,
1028                 .me             = THIS_MODULE,
1029         },
1030         {
1031                 .name           = "hashlimit",
1032                 .revision       = 2,
1033                 .family         = NFPROTO_IPV6,
1034                 .match          = hashlimit_mt_v2,
1035                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo2),
1036                 .usersize       = offsetof(struct xt_hashlimit_mtinfo2, hinfo),
1037                 .checkentry     = hashlimit_mt_check_v2,
1038                 .destroy        = hashlimit_mt_destroy_v2,
1039                 .me             = THIS_MODULE,
1040         },
1041         {
1042                 .name           = "hashlimit",
1043                 .revision       = 3,
1044                 .family         = NFPROTO_IPV6,
1045                 .match          = hashlimit_mt,
1046                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo3),
1047                 .usersize       = offsetof(struct xt_hashlimit_mtinfo3, hinfo),
1048                 .checkentry     = hashlimit_mt_check,
1049                 .destroy        = hashlimit_mt_destroy,
1050                 .me             = THIS_MODULE,
1051         },
1052 #endif
1053 };
1054 
1055 /* PROC stuff */
1056 static void *dl_seq_start(struct seq_file *s, loff_t *pos)
1057         __acquires(htable->lock)
1058 {
1059         struct xt_hashlimit_htable *htable = s->private;
1060         unsigned int *bucket;
1061 
1062         spin_lock_bh(&htable->lock);
1063         if (*pos >= htable->cfg.size)
1064                 return NULL;
1065 
1066         bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
1067         if (!bucket)
1068                 return ERR_PTR(-ENOMEM);
1069 
1070         *bucket = *pos;
1071         return bucket;
1072 }
1073 
1074 static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
1075 {
1076         struct xt_hashlimit_htable *htable = s->private;
1077         unsigned int *bucket = v;
1078 
1079         *pos = ++(*bucket);
1080         if (*pos >= htable->cfg.size) {
1081                 kfree(v);
1082                 return NULL;
1083         }
1084         return bucket;
1085 }
1086 
1087 static void dl_seq_stop(struct seq_file *s, void *v)
1088         __releases(htable->lock)
1089 {
1090         struct xt_hashlimit_htable *htable = s->private;
1091         unsigned int *bucket = v;
1092 
1093         if (!IS_ERR(bucket))
1094                 kfree(bucket);
1095         spin_unlock_bh(&htable->lock);
1096 }
1097 
1098 static void dl_seq_print(struct dsthash_ent *ent, u_int8_t family,
1099                          struct seq_file *s)
1100 {
1101         switch (family) {
1102         case NFPROTO_IPV4:
1103                 seq_printf(s, "%ld %pI4:%u->%pI4:%u %llu %llu %llu\n",
1104                            (long)(ent->expires - jiffies)/HZ,
1105                            &ent->dst.ip.src,
1106                            ntohs(ent->dst.src_port),
1107                            &ent->dst.ip.dst,
1108                            ntohs(ent->dst.dst_port),
1109                            ent->rateinfo.credit, ent->rateinfo.credit_cap,
1110                            ent->rateinfo.cost);
1111                 break;
1112 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1113         case NFPROTO_IPV6:
1114                 seq_printf(s, "%ld %pI6:%u->%pI6:%u %llu %llu %llu\n",
1115                            (long)(ent->expires - jiffies)/HZ,
1116                            &ent->dst.ip6.src,
1117                            ntohs(ent->dst.src_port),
1118                            &ent->dst.ip6.dst,
1119                            ntohs(ent->dst.dst_port),
1120                            ent->rateinfo.credit, ent->rateinfo.credit_cap,
1121                            ent->rateinfo.cost);
1122                 break;
1123 #endif
1124         default:
1125                 BUG();
1126         }
1127 }
1128 
1129 static int dl_seq_real_show_v2(struct dsthash_ent *ent, u_int8_t family,
1130                                struct seq_file *s)
1131 {
1132         const struct xt_hashlimit_htable *ht = s->private;
1133 
1134         spin_lock(&ent->lock);
1135         /* recalculate to show accurate numbers */
1136         rateinfo_recalc(ent, jiffies, ht->cfg.mode, 2);
1137 
1138         dl_seq_print(ent, family, s);
1139 
1140         spin_unlock(&ent->lock);
1141         return seq_has_overflowed(s);
1142 }
1143 
1144 static int dl_seq_real_show_v1(struct dsthash_ent *ent, u_int8_t family,
1145                                struct seq_file *s)
1146 {
1147         const struct xt_hashlimit_htable *ht = s->private;
1148 
1149         spin_lock(&ent->lock);
1150         /* recalculate to show accurate numbers */
1151         rateinfo_recalc(ent, jiffies, ht->cfg.mode, 1);
1152 
1153         dl_seq_print(ent, family, s);
1154 
1155         spin_unlock(&ent->lock);
1156         return seq_has_overflowed(s);
1157 }
1158 
1159 static int dl_seq_real_show(struct dsthash_ent *ent, u_int8_t family,
1160                             struct seq_file *s)
1161 {
1162         const struct xt_hashlimit_htable *ht = s->private;
1163 
1164         spin_lock(&ent->lock);
1165         /* recalculate to show accurate numbers */
1166         rateinfo_recalc(ent, jiffies, ht->cfg.mode, 3);
1167 
1168         dl_seq_print(ent, family, s);
1169 
1170         spin_unlock(&ent->lock);
1171         return seq_has_overflowed(s);
1172 }
1173 
1174 static int dl_seq_show_v2(struct seq_file *s, void *v)
1175 {
1176         struct xt_hashlimit_htable *htable = s->private;
1177         unsigned int *bucket = (unsigned int *)v;
1178         struct dsthash_ent *ent;
1179 
1180         if (!hlist_empty(&htable->hash[*bucket])) {
1181                 hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1182                         if (dl_seq_real_show_v2(ent, htable->family, s))
1183                                 return -1;
1184         }
1185         return 0;
1186 }
1187 
1188 static int dl_seq_show_v1(struct seq_file *s, void *v)
1189 {
1190         struct xt_hashlimit_htable *htable = s->private;
1191         unsigned int *bucket = v;
1192         struct dsthash_ent *ent;
1193 
1194         if (!hlist_empty(&htable->hash[*bucket])) {
1195                 hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1196                         if (dl_seq_real_show_v1(ent, htable->family, s))
1197                                 return -1;
1198         }
1199         return 0;
1200 }
1201 
1202 static int dl_seq_show(struct seq_file *s, void *v)
1203 {
1204         struct xt_hashlimit_htable *htable = s->private;
1205         unsigned int *bucket = v;
1206         struct dsthash_ent *ent;
1207 
1208         if (!hlist_empty(&htable->hash[*bucket])) {
1209                 hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1210                         if (dl_seq_real_show(ent, htable->family, s))
1211                                 return -1;
1212         }
1213         return 0;
1214 }
1215 
1216 static const struct seq_operations dl_seq_ops_v1 = {
1217         .start = dl_seq_start,
1218         .next  = dl_seq_next,
1219         .stop  = dl_seq_stop,
1220         .show  = dl_seq_show_v1
1221 };
1222 
1223 static const struct seq_operations dl_seq_ops_v2 = {
1224         .start = dl_seq_start,
1225         .next  = dl_seq_next,
1226         .stop  = dl_seq_stop,
1227         .show  = dl_seq_show_v2
1228 };
1229 
1230 static const struct seq_operations dl_seq_ops = {
1231         .start = dl_seq_start,
1232         .next  = dl_seq_next,
1233         .stop  = dl_seq_stop,
1234         .show  = dl_seq_show
1235 };
1236 
1237 static int dl_proc_open_v2(struct inode *inode, struct file *file)
1238 {
1239         int ret = seq_open(file, &dl_seq_ops_v2);
1240 
1241         if (!ret) {
1242                 struct seq_file *sf = file->private_data;
1243 
1244                 sf->private = PDE_DATA(inode);
1245         }
1246         return ret;
1247 }
1248 
1249 static int dl_proc_open_v1(struct inode *inode, struct file *file)
1250 {
1251         int ret = seq_open(file, &dl_seq_ops_v1);
1252 
1253         if (!ret) {
1254                 struct seq_file *sf = file->private_data;
1255                 sf->private = PDE_DATA(inode);
1256         }
1257         return ret;
1258 }
1259 
1260 static int dl_proc_open(struct inode *inode, struct file *file)
1261 {
1262         int ret = seq_open(file, &dl_seq_ops);
1263 
1264         if (!ret) {
1265                 struct seq_file *sf = file->private_data;
1266 
1267                 sf->private = PDE_DATA(inode);
1268         }
1269         return ret;
1270 }
1271 
1272 static const struct file_operations dl_file_ops_v2 = {
1273         .owner   = THIS_MODULE,
1274         .open    = dl_proc_open_v2,
1275         .read    = seq_read,
1276         .llseek  = seq_lseek,
1277         .release = seq_release
1278 };
1279 
1280 static const struct file_operations dl_file_ops_v1 = {
1281         .owner   = THIS_MODULE,
1282         .open    = dl_proc_open_v1,
1283         .read    = seq_read,
1284         .llseek  = seq_lseek,
1285         .release = seq_release
1286 };
1287 
1288 static const struct file_operations dl_file_ops = {
1289         .owner   = THIS_MODULE,
1290         .open    = dl_proc_open,
1291         .read    = seq_read,
1292         .llseek  = seq_lseek,
1293         .release = seq_release
1294 };
1295 
1296 static int __net_init hashlimit_proc_net_init(struct net *net)
1297 {
1298         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1299 
1300         hashlimit_net->ipt_hashlimit = proc_mkdir("ipt_hashlimit", net->proc_net);
1301         if (!hashlimit_net->ipt_hashlimit)
1302                 return -ENOMEM;
1303 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1304         hashlimit_net->ip6t_hashlimit = proc_mkdir("ip6t_hashlimit", net->proc_net);
1305         if (!hashlimit_net->ip6t_hashlimit) {
1306                 remove_proc_entry("ipt_hashlimit", net->proc_net);
1307                 return -ENOMEM;
1308         }
1309 #endif
1310         return 0;
1311 }
1312 
1313 static void __net_exit hashlimit_proc_net_exit(struct net *net)
1314 {
1315         struct xt_hashlimit_htable *hinfo;
1316         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1317 
1318         /* hashlimit_net_exit() is called before hashlimit_mt_destroy().
1319          * Make sure that the parent ipt_hashlimit and ip6t_hashlimit proc
1320          * entries is empty before trying to remove it.
1321          */
1322         mutex_lock(&hashlimit_mutex);
1323         hlist_for_each_entry(hinfo, &hashlimit_net->htables, node)
1324                 htable_remove_proc_entry(hinfo);
1325         hashlimit_net->ipt_hashlimit = NULL;
1326         hashlimit_net->ip6t_hashlimit = NULL;
1327         mutex_unlock(&hashlimit_mutex);
1328 
1329         remove_proc_entry("ipt_hashlimit", net->proc_net);
1330 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1331         remove_proc_entry("ip6t_hashlimit", net->proc_net);
1332 #endif
1333 }
1334 
1335 static int __net_init hashlimit_net_init(struct net *net)
1336 {
1337         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1338 
1339         INIT_HLIST_HEAD(&hashlimit_net->htables);
1340         return hashlimit_proc_net_init(net);
1341 }
1342 
1343 static void __net_exit hashlimit_net_exit(struct net *net)
1344 {
1345         hashlimit_proc_net_exit(net);
1346 }
1347 
1348 static struct pernet_operations hashlimit_net_ops = {
1349         .init   = hashlimit_net_init,
1350         .exit   = hashlimit_net_exit,
1351         .id     = &hashlimit_net_id,
1352         .size   = sizeof(struct hashlimit_net),
1353 };
1354 
1355 static int __init hashlimit_mt_init(void)
1356 {
1357         int err;
1358 
1359         err = register_pernet_subsys(&hashlimit_net_ops);
1360         if (err < 0)
1361                 return err;
1362         err = xt_register_matches(hashlimit_mt_reg,
1363               ARRAY_SIZE(hashlimit_mt_reg));
1364         if (err < 0)
1365                 goto err1;
1366 
1367         err = -ENOMEM;
1368         hashlimit_cachep = kmem_cache_create("xt_hashlimit",
1369                                             sizeof(struct dsthash_ent), 0, 0,
1370                                             NULL);
1371         if (!hashlimit_cachep) {
1372                 pr_warn("unable to create slab cache\n");
1373                 goto err2;
1374         }
1375         return 0;
1376 
1377 err2:
1378         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
1379 err1:
1380         unregister_pernet_subsys(&hashlimit_net_ops);
1381         return err;
1382 
1383 }
1384 
1385 static void __exit hashlimit_mt_exit(void)
1386 {
1387         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
1388         unregister_pernet_subsys(&hashlimit_net_ops);
1389 
1390         rcu_barrier_bh();
1391         kmem_cache_destroy(hashlimit_cachep);
1392 }
1393 
1394 module_init(hashlimit_mt_init);
1395 module_exit(hashlimit_mt_exit);
1396 

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