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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 
 39 MODULE_LICENSE("GPL");
 40 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
 41 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
 42 MODULE_DESCRIPTION("Xtables: per hash-bucket rate-limit match");
 43 MODULE_ALIAS("ipt_hashlimit");
 44 MODULE_ALIAS("ip6t_hashlimit");
 45 
 46 struct hashlimit_net {
 47         struct hlist_head       htables;
 48         struct proc_dir_entry   *ipt_hashlimit;
 49         struct proc_dir_entry   *ip6t_hashlimit;
 50 };
 51 
 52 static unsigned int hashlimit_net_id;
 53 static inline struct hashlimit_net *hashlimit_pernet(struct net *net)
 54 {
 55         return net_generic(net, hashlimit_net_id);
 56 }
 57 
 58 /* need to declare this at the top */
 59 static const struct file_operations dl_file_ops_v1;
 60 static const struct file_operations dl_file_ops;
 61 
 62 /* hash table crap */
 63 struct dsthash_dst {
 64         union {
 65                 struct {
 66                         __be32 src;
 67                         __be32 dst;
 68                 } ip;
 69 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 70                 struct {
 71                         __be32 src[4];
 72                         __be32 dst[4];
 73                 } ip6;
 74 #endif
 75         };
 76         __be16 src_port;
 77         __be16 dst_port;
 78 };
 79 
 80 struct dsthash_ent {
 81         /* static / read-only parts in the beginning */
 82         struct hlist_node node;
 83         struct dsthash_dst dst;
 84 
 85         /* modified structure members in the end */
 86         spinlock_t lock;
 87         unsigned long expires;          /* precalculated expiry time */
 88         struct {
 89                 unsigned long prev;     /* last modification */
 90                 u_int64_t credit;
 91                 u_int64_t credit_cap, cost;
 92         } rateinfo;
 93         struct rcu_head rcu;
 94 };
 95 
 96 struct xt_hashlimit_htable {
 97         struct hlist_node node;         /* global list of all htables */
 98         int use;
 99         u_int8_t family;
100         bool rnd_initialized;
101 
102         struct hashlimit_cfg2 cfg;      /* config */
103 
104         /* used internally */
105         spinlock_t lock;                /* lock for list_head */
106         u_int32_t rnd;                  /* random seed for hash */
107         unsigned int count;             /* number entries in table */
108         struct delayed_work gc_work;
109 
110         /* seq_file stuff */
111         struct proc_dir_entry *pde;
112         const char *name;
113         struct net *net;
114 
115         struct hlist_head hash[0];      /* hashtable itself */
116 };
117 
118 static int
119 cfg_copy(struct hashlimit_cfg2 *to, void *from, int revision)
120 {
121         if (revision == 1) {
122                 struct hashlimit_cfg1 *cfg = from;
123 
124                 to->mode = cfg->mode;
125                 to->avg = cfg->avg;
126                 to->burst = cfg->burst;
127                 to->size = cfg->size;
128                 to->max = cfg->max;
129                 to->gc_interval = cfg->gc_interval;
130                 to->expire = cfg->expire;
131                 to->srcmask = cfg->srcmask;
132                 to->dstmask = cfg->dstmask;
133         } else if (revision == 2) {
134                 memcpy(to, from, sizeof(struct hashlimit_cfg2));
135         } else {
136                 return -EINVAL;
137         }
138 
139         return 0;
140 }
141 
142 static DEFINE_MUTEX(hashlimit_mutex);   /* protects htables list */
143 static struct kmem_cache *hashlimit_cachep __read_mostly;
144 
145 static inline bool dst_cmp(const struct dsthash_ent *ent,
146                            const struct dsthash_dst *b)
147 {
148         return !memcmp(&ent->dst, b, sizeof(ent->dst));
149 }
150 
151 static u_int32_t
152 hash_dst(const struct xt_hashlimit_htable *ht, const struct dsthash_dst *dst)
153 {
154         u_int32_t hash = jhash2((const u32 *)dst,
155                                 sizeof(*dst)/sizeof(u32),
156                                 ht->rnd);
157         /*
158          * Instead of returning hash % ht->cfg.size (implying a divide)
159          * we return the high 32 bits of the (hash * ht->cfg.size) that will
160          * give results between [0 and cfg.size-1] and same hash distribution,
161          * but using a multiply, less expensive than a divide
162          */
163         return reciprocal_scale(hash, ht->cfg.size);
164 }
165 
166 static struct dsthash_ent *
167 dsthash_find(const struct xt_hashlimit_htable *ht,
168              const struct dsthash_dst *dst)
169 {
170         struct dsthash_ent *ent;
171         u_int32_t hash = hash_dst(ht, dst);
172 
173         if (!hlist_empty(&ht->hash[hash])) {
174                 hlist_for_each_entry_rcu(ent, &ht->hash[hash], node)
175                         if (dst_cmp(ent, dst)) {
176                                 spin_lock(&ent->lock);
177                                 return ent;
178                         }
179         }
180         return NULL;
181 }
182 
183 /* allocate dsthash_ent, initialize dst, put in htable and lock it */
184 static struct dsthash_ent *
185 dsthash_alloc_init(struct xt_hashlimit_htable *ht,
186                    const struct dsthash_dst *dst, bool *race)
187 {
188         struct dsthash_ent *ent;
189 
190         spin_lock(&ht->lock);
191 
192         /* Two or more packets may race to create the same entry in the
193          * hashtable, double check if this packet lost race.
194          */
195         ent = dsthash_find(ht, dst);
196         if (ent != NULL) {
197                 spin_unlock(&ht->lock);
198                 *race = true;
199                 return ent;
200         }
201 
202         /* initialize hash with random val at the time we allocate
203          * the first hashtable entry */
204         if (unlikely(!ht->rnd_initialized)) {
205                 get_random_bytes(&ht->rnd, sizeof(ht->rnd));
206                 ht->rnd_initialized = true;
207         }
208 
209         if (ht->cfg.max && ht->count >= ht->cfg.max) {
210                 /* FIXME: do something. question is what.. */
211                 net_err_ratelimited("max count of %u reached\n", ht->cfg.max);
212                 ent = NULL;
213         } else
214                 ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
215         if (ent) {
216                 memcpy(&ent->dst, dst, sizeof(ent->dst));
217                 spin_lock_init(&ent->lock);
218 
219                 spin_lock(&ent->lock);
220                 hlist_add_head_rcu(&ent->node, &ht->hash[hash_dst(ht, dst)]);
221                 ht->count++;
222         }
223         spin_unlock(&ht->lock);
224         return ent;
225 }
226 
227 static void dsthash_free_rcu(struct rcu_head *head)
228 {
229         struct dsthash_ent *ent = container_of(head, struct dsthash_ent, rcu);
230 
231         kmem_cache_free(hashlimit_cachep, ent);
232 }
233 
234 static inline void
235 dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent)
236 {
237         hlist_del_rcu(&ent->node);
238         call_rcu_bh(&ent->rcu, dsthash_free_rcu);
239         ht->count--;
240 }
241 static void htable_gc(struct work_struct *work);
242 
243 static int htable_create(struct net *net, struct hashlimit_cfg2 *cfg,
244                          const char *name, u_int8_t family,
245                          struct xt_hashlimit_htable **out_hinfo,
246                          int revision)
247 {
248         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
249         struct xt_hashlimit_htable *hinfo;
250         unsigned int size, i;
251         int ret;
252 
253         if (cfg->size) {
254                 size = cfg->size;
255         } else {
256                 size = (totalram_pages << PAGE_SHIFT) / 16384 /
257                        sizeof(struct list_head);
258                 if (totalram_pages > 1024 * 1024 * 1024 / PAGE_SIZE)
259                         size = 8192;
260                 if (size < 16)
261                         size = 16;
262         }
263         /* FIXME: don't use vmalloc() here or anywhere else -HW */
264         hinfo = vmalloc(sizeof(struct xt_hashlimit_htable) +
265                         sizeof(struct list_head) * size);
266         if (hinfo == NULL)
267                 return -ENOMEM;
268         *out_hinfo = hinfo;
269 
270         /* copy match config into hashtable config */
271         ret = cfg_copy(&hinfo->cfg, (void *)cfg, 2);
272 
273         if (ret)
274                 return ret;
275 
276         hinfo->cfg.size = size;
277         if (hinfo->cfg.max == 0)
278                 hinfo->cfg.max = 8 * hinfo->cfg.size;
279         else if (hinfo->cfg.max < hinfo->cfg.size)
280                 hinfo->cfg.max = hinfo->cfg.size;
281 
282         for (i = 0; i < hinfo->cfg.size; i++)
283                 INIT_HLIST_HEAD(&hinfo->hash[i]);
284 
285         hinfo->use = 1;
286         hinfo->count = 0;
287         hinfo->family = family;
288         hinfo->rnd_initialized = false;
289         hinfo->name = kstrdup(name, GFP_KERNEL);
290         if (!hinfo->name) {
291                 vfree(hinfo);
292                 return -ENOMEM;
293         }
294         spin_lock_init(&hinfo->lock);
295 
296         hinfo->pde = proc_create_data(name, 0,
297                 (family == NFPROTO_IPV4) ?
298                 hashlimit_net->ipt_hashlimit : hashlimit_net->ip6t_hashlimit,
299                 (revision == 1) ? &dl_file_ops_v1 : &dl_file_ops,
300                 hinfo);
301         if (hinfo->pde == NULL) {
302                 kfree(hinfo->name);
303                 vfree(hinfo);
304                 return -ENOMEM;
305         }
306         hinfo->net = net;
307 
308         INIT_DEFERRABLE_WORK(&hinfo->gc_work, htable_gc);
309         queue_delayed_work(system_power_efficient_wq, &hinfo->gc_work,
310                            msecs_to_jiffies(hinfo->cfg.gc_interval));
311 
312         hlist_add_head(&hinfo->node, &hashlimit_net->htables);
313 
314         return 0;
315 }
316 
317 static bool select_all(const struct xt_hashlimit_htable *ht,
318                        const struct dsthash_ent *he)
319 {
320         return 1;
321 }
322 
323 static bool select_gc(const struct xt_hashlimit_htable *ht,
324                       const struct dsthash_ent *he)
325 {
326         return time_after_eq(jiffies, he->expires);
327 }
328 
329 static void htable_selective_cleanup(struct xt_hashlimit_htable *ht,
330                         bool (*select)(const struct xt_hashlimit_htable *ht,
331                                       const struct dsthash_ent *he))
332 {
333         unsigned int i;
334 
335         for (i = 0; i < ht->cfg.size; i++) {
336                 struct dsthash_ent *dh;
337                 struct hlist_node *n;
338 
339                 spin_lock_bh(&ht->lock);
340                 hlist_for_each_entry_safe(dh, n, &ht->hash[i], node) {
341                         if ((*select)(ht, dh))
342                                 dsthash_free(ht, dh);
343                 }
344                 spin_unlock_bh(&ht->lock);
345                 cond_resched();
346         }
347 }
348 
349 static void htable_gc(struct work_struct *work)
350 {
351         struct xt_hashlimit_htable *ht;
352 
353         ht = container_of(work, struct xt_hashlimit_htable, gc_work.work);
354 
355         htable_selective_cleanup(ht, select_gc);
356 
357         queue_delayed_work(system_power_efficient_wq,
358                            &ht->gc_work, msecs_to_jiffies(ht->cfg.gc_interval));
359 }
360 
361 static void htable_remove_proc_entry(struct xt_hashlimit_htable *hinfo)
362 {
363         struct hashlimit_net *hashlimit_net = hashlimit_pernet(hinfo->net);
364         struct proc_dir_entry *parent;
365 
366         if (hinfo->family == NFPROTO_IPV4)
367                 parent = hashlimit_net->ipt_hashlimit;
368         else
369                 parent = hashlimit_net->ip6t_hashlimit;
370 
371         if (parent != NULL)
372                 remove_proc_entry(hinfo->name, parent);
373 }
374 
375 static void htable_destroy(struct xt_hashlimit_htable *hinfo)
376 {
377         cancel_delayed_work_sync(&hinfo->gc_work);
378         htable_remove_proc_entry(hinfo);
379         htable_selective_cleanup(hinfo, select_all);
380         kfree(hinfo->name);
381         vfree(hinfo);
382 }
383 
384 static struct xt_hashlimit_htable *htable_find_get(struct net *net,
385                                                    const char *name,
386                                                    u_int8_t family)
387 {
388         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
389         struct xt_hashlimit_htable *hinfo;
390 
391         hlist_for_each_entry(hinfo, &hashlimit_net->htables, node) {
392                 if (!strcmp(name, hinfo->name) &&
393                     hinfo->family == family) {
394                         hinfo->use++;
395                         return hinfo;
396                 }
397         }
398         return NULL;
399 }
400 
401 static void htable_put(struct xt_hashlimit_htable *hinfo)
402 {
403         mutex_lock(&hashlimit_mutex);
404         if (--hinfo->use == 0) {
405                 hlist_del(&hinfo->node);
406                 htable_destroy(hinfo);
407         }
408         mutex_unlock(&hashlimit_mutex);
409 }
410 
411 /* The algorithm used is the Simple Token Bucket Filter (TBF)
412  * see net/sched/sch_tbf.c in the linux source tree
413  */
414 
415 /* Rusty: This is my (non-mathematically-inclined) understanding of
416    this algorithm.  The `average rate' in jiffies becomes your initial
417    amount of credit `credit' and the most credit you can ever have
418    `credit_cap'.  The `peak rate' becomes the cost of passing the
419    test, `cost'.
420 
421    `prev' tracks the last packet hit: you gain one credit per jiffy.
422    If you get credit balance more than this, the extra credit is
423    discarded.  Every time the match passes, you lose `cost' credits;
424    if you don't have that many, the test fails.
425 
426    See Alexey's formal explanation in net/sched/sch_tbf.c.
427 
428    To get the maximum range, we multiply by this factor (ie. you get N
429    credits per jiffy).  We want to allow a rate as low as 1 per day
430    (slowest userspace tool allows), which means
431    CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
432 */
433 #define MAX_CPJ_v1 (0xFFFFFFFF / (HZ*60*60*24))
434 #define MAX_CPJ (0xFFFFFFFFFFFFFFFFULL / (HZ*60*60*24))
435 
436 /* Repeated shift and or gives us all 1s, final shift and add 1 gives
437  * us the power of 2 below the theoretical max, so GCC simply does a
438  * shift. */
439 #define _POW2_BELOW2(x) ((x)|((x)>>1))
440 #define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
441 #define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
442 #define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
443 #define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
444 #define _POW2_BELOW64(x) (_POW2_BELOW32(x)|_POW2_BELOW32((x)>>32))
445 #define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
446 #define POW2_BELOW64(x) ((_POW2_BELOW64(x)>>1) + 1)
447 
448 #define CREDITS_PER_JIFFY POW2_BELOW64(MAX_CPJ)
449 #define CREDITS_PER_JIFFY_v1 POW2_BELOW32(MAX_CPJ_v1)
450 
451 /* in byte mode, the lowest possible rate is one packet/second.
452  * credit_cap is used as a counter that tells us how many times we can
453  * refill the "credits available" counter when it becomes empty.
454  */
455 #define MAX_CPJ_BYTES (0xFFFFFFFF / HZ)
456 #define CREDITS_PER_JIFFY_BYTES POW2_BELOW32(MAX_CPJ_BYTES)
457 
458 static u32 xt_hashlimit_len_to_chunks(u32 len)
459 {
460         return (len >> XT_HASHLIMIT_BYTE_SHIFT) + 1;
461 }
462 
463 /* Precision saver. */
464 static u64 user2credits(u64 user, int revision)
465 {
466         u64 scale = (revision == 1) ?
467                 XT_HASHLIMIT_SCALE : XT_HASHLIMIT_SCALE_v2;
468         u64 cpj = (revision == 1) ?
469                 CREDITS_PER_JIFFY_v1 : CREDITS_PER_JIFFY;
470 
471         /* Avoid overflow: divide the constant operands first */
472         if (scale >= HZ * cpj)
473                 return div64_u64(user, div64_u64(scale, HZ * cpj));
474 
475         return user * div64_u64(HZ * cpj, scale);
476 }
477 
478 static u32 user2credits_byte(u32 user)
479 {
480         u64 us = user;
481         us *= HZ * CREDITS_PER_JIFFY_BYTES;
482         return (u32) (us >> 32);
483 }
484 
485 static void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now,
486                             u32 mode, int revision)
487 {
488         unsigned long delta = now - dh->rateinfo.prev;
489         u64 cap, cpj;
490 
491         if (delta == 0)
492                 return;
493 
494         dh->rateinfo.prev = now;
495 
496         if (mode & XT_HASHLIMIT_BYTES) {
497                 u64 tmp = dh->rateinfo.credit;
498                 dh->rateinfo.credit += CREDITS_PER_JIFFY_BYTES * delta;
499                 cap = CREDITS_PER_JIFFY_BYTES * HZ;
500                 if (tmp >= dh->rateinfo.credit) {/* overflow */
501                         dh->rateinfo.credit = cap;
502                         return;
503                 }
504         } else {
505                 cpj = (revision == 1) ?
506                         CREDITS_PER_JIFFY_v1 : CREDITS_PER_JIFFY;
507                 dh->rateinfo.credit += delta * cpj;
508                 cap = dh->rateinfo.credit_cap;
509         }
510         if (dh->rateinfo.credit > cap)
511                 dh->rateinfo.credit = cap;
512 }
513 
514 static void rateinfo_init(struct dsthash_ent *dh,
515                           struct xt_hashlimit_htable *hinfo, int revision)
516 {
517         dh->rateinfo.prev = jiffies;
518         if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) {
519                 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
520                 dh->rateinfo.cost = user2credits_byte(hinfo->cfg.avg);
521                 dh->rateinfo.credit_cap = hinfo->cfg.burst;
522         } else {
523                 dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
524                                                    hinfo->cfg.burst, revision);
525                 dh->rateinfo.cost = user2credits(hinfo->cfg.avg, revision);
526                 dh->rateinfo.credit_cap = dh->rateinfo.credit;
527         }
528 }
529 
530 static inline __be32 maskl(__be32 a, unsigned int l)
531 {
532         return l ? htonl(ntohl(a) & ~0 << (32 - l)) : 0;
533 }
534 
535 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
536 static void hashlimit_ipv6_mask(__be32 *i, unsigned int p)
537 {
538         switch (p) {
539         case 0 ... 31:
540                 i[0] = maskl(i[0], p);
541                 i[1] = i[2] = i[3] = 0;
542                 break;
543         case 32 ... 63:
544                 i[1] = maskl(i[1], p - 32);
545                 i[2] = i[3] = 0;
546                 break;
547         case 64 ... 95:
548                 i[2] = maskl(i[2], p - 64);
549                 i[3] = 0;
550                 break;
551         case 96 ... 127:
552                 i[3] = maskl(i[3], p - 96);
553                 break;
554         case 128:
555                 break;
556         }
557 }
558 #endif
559 
560 static int
561 hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
562                    struct dsthash_dst *dst,
563                    const struct sk_buff *skb, unsigned int protoff)
564 {
565         __be16 _ports[2], *ports;
566         u8 nexthdr;
567         int poff;
568 
569         memset(dst, 0, sizeof(*dst));
570 
571         switch (hinfo->family) {
572         case NFPROTO_IPV4:
573                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
574                         dst->ip.dst = maskl(ip_hdr(skb)->daddr,
575                                       hinfo->cfg.dstmask);
576                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
577                         dst->ip.src = maskl(ip_hdr(skb)->saddr,
578                                       hinfo->cfg.srcmask);
579 
580                 if (!(hinfo->cfg.mode &
581                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
582                         return 0;
583                 nexthdr = ip_hdr(skb)->protocol;
584                 break;
585 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
586         case NFPROTO_IPV6:
587         {
588                 __be16 frag_off;
589 
590                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) {
591                         memcpy(&dst->ip6.dst, &ipv6_hdr(skb)->daddr,
592                                sizeof(dst->ip6.dst));
593                         hashlimit_ipv6_mask(dst->ip6.dst, hinfo->cfg.dstmask);
594                 }
595                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) {
596                         memcpy(&dst->ip6.src, &ipv6_hdr(skb)->saddr,
597                                sizeof(dst->ip6.src));
598                         hashlimit_ipv6_mask(dst->ip6.src, hinfo->cfg.srcmask);
599                 }
600 
601                 if (!(hinfo->cfg.mode &
602                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
603                         return 0;
604                 nexthdr = ipv6_hdr(skb)->nexthdr;
605                 protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, &frag_off);
606                 if ((int)protoff < 0)
607                         return -1;
608                 break;
609         }
610 #endif
611         default:
612                 BUG();
613                 return 0;
614         }
615 
616         poff = proto_ports_offset(nexthdr);
617         if (poff >= 0) {
618                 ports = skb_header_pointer(skb, protoff + poff, sizeof(_ports),
619                                            &_ports);
620         } else {
621                 _ports[0] = _ports[1] = 0;
622                 ports = _ports;
623         }
624         if (!ports)
625                 return -1;
626         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT)
627                 dst->src_port = ports[0];
628         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT)
629                 dst->dst_port = ports[1];
630         return 0;
631 }
632 
633 static u32 hashlimit_byte_cost(unsigned int len, struct dsthash_ent *dh)
634 {
635         u64 tmp = xt_hashlimit_len_to_chunks(len);
636         tmp = tmp * dh->rateinfo.cost;
637 
638         if (unlikely(tmp > CREDITS_PER_JIFFY_BYTES * HZ))
639                 tmp = CREDITS_PER_JIFFY_BYTES * HZ;
640 
641         if (dh->rateinfo.credit < tmp && dh->rateinfo.credit_cap) {
642                 dh->rateinfo.credit_cap--;
643                 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
644         }
645         return (u32) tmp;
646 }
647 
648 static bool
649 hashlimit_mt_common(const struct sk_buff *skb, struct xt_action_param *par,
650                     struct xt_hashlimit_htable *hinfo,
651                     const struct hashlimit_cfg2 *cfg, int revision)
652 {
653         unsigned long now = jiffies;
654         struct dsthash_ent *dh;
655         struct dsthash_dst dst;
656         bool race = false;
657         u64 cost;
658 
659         if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0)
660                 goto hotdrop;
661 
662         rcu_read_lock_bh();
663         dh = dsthash_find(hinfo, &dst);
664         if (dh == NULL) {
665                 dh = dsthash_alloc_init(hinfo, &dst, &race);
666                 if (dh == NULL) {
667                         rcu_read_unlock_bh();
668                         goto hotdrop;
669                 } else if (race) {
670                         /* Already got an entry, update expiration timeout */
671                         dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
672                         rateinfo_recalc(dh, now, hinfo->cfg.mode, revision);
673                 } else {
674                         dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
675                         rateinfo_init(dh, hinfo, revision);
676                 }
677         } else {
678                 /* update expiration timeout */
679                 dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
680                 rateinfo_recalc(dh, now, hinfo->cfg.mode, revision);
681         }
682 
683         if (cfg->mode & XT_HASHLIMIT_BYTES)
684                 cost = hashlimit_byte_cost(skb->len, dh);
685         else
686                 cost = dh->rateinfo.cost;
687 
688         if (dh->rateinfo.credit >= cost) {
689                 /* below the limit */
690                 dh->rateinfo.credit -= cost;
691                 spin_unlock(&dh->lock);
692                 rcu_read_unlock_bh();
693                 return !(cfg->mode & XT_HASHLIMIT_INVERT);
694         }
695 
696         spin_unlock(&dh->lock);
697         rcu_read_unlock_bh();
698         /* default match is underlimit - so over the limit, we need to invert */
699         return cfg->mode & XT_HASHLIMIT_INVERT;
700 
701  hotdrop:
702         par->hotdrop = true;
703         return false;
704 }
705 
706 static bool
707 hashlimit_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
708 {
709         const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
710         struct xt_hashlimit_htable *hinfo = info->hinfo;
711         struct hashlimit_cfg2 cfg = {};
712         int ret;
713 
714         ret = cfg_copy(&cfg, (void *)&info->cfg, 1);
715 
716         if (ret)
717                 return ret;
718 
719         return hashlimit_mt_common(skb, par, hinfo, &cfg, 1);
720 }
721 
722 static bool
723 hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par)
724 {
725         const struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
726         struct xt_hashlimit_htable *hinfo = info->hinfo;
727 
728         return hashlimit_mt_common(skb, par, hinfo, &info->cfg, 2);
729 }
730 
731 static int hashlimit_mt_check_common(const struct xt_mtchk_param *par,
732                                      struct xt_hashlimit_htable **hinfo,
733                                      struct hashlimit_cfg2 *cfg,
734                                      const char *name, int revision)
735 {
736         struct net *net = par->net;
737         int ret;
738 
739         if (cfg->gc_interval == 0 || cfg->expire == 0)
740                 return -EINVAL;
741         if (par->family == NFPROTO_IPV4) {
742                 if (cfg->srcmask > 32 || cfg->dstmask > 32)
743                         return -EINVAL;
744         } else {
745                 if (cfg->srcmask > 128 || cfg->dstmask > 128)
746                         return -EINVAL;
747         }
748 
749         if (cfg->mode & ~XT_HASHLIMIT_ALL) {
750                 pr_info("Unknown mode mask %X, kernel too old?\n",
751                                                 cfg->mode);
752                 return -EINVAL;
753         }
754 
755         /* Check for overflow. */
756         if (cfg->mode & XT_HASHLIMIT_BYTES) {
757                 if (user2credits_byte(cfg->avg) == 0) {
758                         pr_info("overflow, rate too high: %llu\n", cfg->avg);
759                         return -EINVAL;
760                 }
761         } else if (cfg->burst == 0 ||
762                     user2credits(cfg->avg * cfg->burst, revision) <
763                     user2credits(cfg->avg, revision)) {
764                         pr_info("overflow, try lower: %llu/%llu\n",
765                                 cfg->avg, cfg->burst);
766                         return -ERANGE;
767         }
768 
769         mutex_lock(&hashlimit_mutex);
770         *hinfo = htable_find_get(net, name, par->family);
771         if (*hinfo == NULL) {
772                 ret = htable_create(net, cfg, name, par->family,
773                                     hinfo, revision);
774                 if (ret < 0) {
775                         mutex_unlock(&hashlimit_mutex);
776                         return ret;
777                 }
778         }
779         mutex_unlock(&hashlimit_mutex);
780 
781         return 0;
782 }
783 
784 static int hashlimit_mt_check_v1(const struct xt_mtchk_param *par)
785 {
786         struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
787         struct hashlimit_cfg2 cfg = {};
788         int ret;
789 
790         if (info->name[sizeof(info->name) - 1] != '\0')
791                 return -EINVAL;
792 
793         ret = cfg_copy(&cfg, (void *)&info->cfg, 1);
794 
795         if (ret)
796                 return ret;
797 
798         return hashlimit_mt_check_common(par, &info->hinfo,
799                                          &cfg, info->name, 1);
800 }
801 
802 static int hashlimit_mt_check(const struct xt_mtchk_param *par)
803 {
804         struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
805 
806         if (info->name[sizeof(info->name) - 1] != '\0')
807                 return -EINVAL;
808 
809         return hashlimit_mt_check_common(par, &info->hinfo, &info->cfg,
810                                          info->name, 2);
811 }
812 
813 static void hashlimit_mt_destroy_v1(const struct xt_mtdtor_param *par)
814 {
815         const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
816 
817         htable_put(info->hinfo);
818 }
819 
820 static void hashlimit_mt_destroy(const struct xt_mtdtor_param *par)
821 {
822         const struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
823 
824         htable_put(info->hinfo);
825 }
826 
827 static struct xt_match hashlimit_mt_reg[] __read_mostly = {
828         {
829                 .name           = "hashlimit",
830                 .revision       = 1,
831                 .family         = NFPROTO_IPV4,
832                 .match          = hashlimit_mt_v1,
833                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
834                 .usersize       = offsetof(struct xt_hashlimit_mtinfo1, hinfo),
835                 .checkentry     = hashlimit_mt_check_v1,
836                 .destroy        = hashlimit_mt_destroy_v1,
837                 .me             = THIS_MODULE,
838         },
839         {
840                 .name           = "hashlimit",
841                 .revision       = 2,
842                 .family         = NFPROTO_IPV4,
843                 .match          = hashlimit_mt,
844                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo2),
845                 .usersize       = offsetof(struct xt_hashlimit_mtinfo2, hinfo),
846                 .checkentry     = hashlimit_mt_check,
847                 .destroy        = hashlimit_mt_destroy,
848                 .me             = THIS_MODULE,
849         },
850 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
851         {
852                 .name           = "hashlimit",
853                 .revision       = 1,
854                 .family         = NFPROTO_IPV6,
855                 .match          = hashlimit_mt_v1,
856                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
857                 .usersize       = offsetof(struct xt_hashlimit_mtinfo1, hinfo),
858                 .checkentry     = hashlimit_mt_check_v1,
859                 .destroy        = hashlimit_mt_destroy_v1,
860                 .me             = THIS_MODULE,
861         },
862         {
863                 .name           = "hashlimit",
864                 .revision       = 2,
865                 .family         = NFPROTO_IPV6,
866                 .match          = hashlimit_mt,
867                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo2),
868                 .usersize       = offsetof(struct xt_hashlimit_mtinfo2, hinfo),
869                 .checkentry     = hashlimit_mt_check,
870                 .destroy        = hashlimit_mt_destroy,
871                 .me             = THIS_MODULE,
872         },
873 #endif
874 };
875 
876 /* PROC stuff */
877 static void *dl_seq_start(struct seq_file *s, loff_t *pos)
878         __acquires(htable->lock)
879 {
880         struct xt_hashlimit_htable *htable = s->private;
881         unsigned int *bucket;
882 
883         spin_lock_bh(&htable->lock);
884         if (*pos >= htable->cfg.size)
885                 return NULL;
886 
887         bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
888         if (!bucket)
889                 return ERR_PTR(-ENOMEM);
890 
891         *bucket = *pos;
892         return bucket;
893 }
894 
895 static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
896 {
897         struct xt_hashlimit_htable *htable = s->private;
898         unsigned int *bucket = v;
899 
900         *pos = ++(*bucket);
901         if (*pos >= htable->cfg.size) {
902                 kfree(v);
903                 return NULL;
904         }
905         return bucket;
906 }
907 
908 static void dl_seq_stop(struct seq_file *s, void *v)
909         __releases(htable->lock)
910 {
911         struct xt_hashlimit_htable *htable = s->private;
912         unsigned int *bucket = v;
913 
914         if (!IS_ERR(bucket))
915                 kfree(bucket);
916         spin_unlock_bh(&htable->lock);
917 }
918 
919 static void dl_seq_print(struct dsthash_ent *ent, u_int8_t family,
920                          struct seq_file *s)
921 {
922         switch (family) {
923         case NFPROTO_IPV4:
924                 seq_printf(s, "%ld %pI4:%u->%pI4:%u %llu %llu %llu\n",
925                            (long)(ent->expires - jiffies)/HZ,
926                            &ent->dst.ip.src,
927                            ntohs(ent->dst.src_port),
928                            &ent->dst.ip.dst,
929                            ntohs(ent->dst.dst_port),
930                            ent->rateinfo.credit, ent->rateinfo.credit_cap,
931                            ent->rateinfo.cost);
932                 break;
933 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
934         case NFPROTO_IPV6:
935                 seq_printf(s, "%ld %pI6:%u->%pI6:%u %llu %llu %llu\n",
936                            (long)(ent->expires - jiffies)/HZ,
937                            &ent->dst.ip6.src,
938                            ntohs(ent->dst.src_port),
939                            &ent->dst.ip6.dst,
940                            ntohs(ent->dst.dst_port),
941                            ent->rateinfo.credit, ent->rateinfo.credit_cap,
942                            ent->rateinfo.cost);
943                 break;
944 #endif
945         default:
946                 BUG();
947         }
948 }
949 
950 static int dl_seq_real_show_v1(struct dsthash_ent *ent, u_int8_t family,
951                                struct seq_file *s)
952 {
953         const struct xt_hashlimit_htable *ht = s->private;
954 
955         spin_lock(&ent->lock);
956         /* recalculate to show accurate numbers */
957         rateinfo_recalc(ent, jiffies, ht->cfg.mode, 1);
958 
959         dl_seq_print(ent, family, s);
960 
961         spin_unlock(&ent->lock);
962         return seq_has_overflowed(s);
963 }
964 
965 static int dl_seq_real_show(struct dsthash_ent *ent, u_int8_t family,
966                             struct seq_file *s)
967 {
968         const struct xt_hashlimit_htable *ht = s->private;
969 
970         spin_lock(&ent->lock);
971         /* recalculate to show accurate numbers */
972         rateinfo_recalc(ent, jiffies, ht->cfg.mode, 2);
973 
974         dl_seq_print(ent, family, s);
975 
976         spin_unlock(&ent->lock);
977         return seq_has_overflowed(s);
978 }
979 
980 static int dl_seq_show_v1(struct seq_file *s, void *v)
981 {
982         struct xt_hashlimit_htable *htable = s->private;
983         unsigned int *bucket = v;
984         struct dsthash_ent *ent;
985 
986         if (!hlist_empty(&htable->hash[*bucket])) {
987                 hlist_for_each_entry(ent, &htable->hash[*bucket], node)
988                         if (dl_seq_real_show_v1(ent, htable->family, s))
989                                 return -1;
990         }
991         return 0;
992 }
993 
994 static int dl_seq_show(struct seq_file *s, void *v)
995 {
996         struct xt_hashlimit_htable *htable = s->private;
997         unsigned int *bucket = v;
998         struct dsthash_ent *ent;
999 
1000         if (!hlist_empty(&htable->hash[*bucket])) {
1001                 hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1002                         if (dl_seq_real_show(ent, htable->family, s))
1003                                 return -1;
1004         }
1005         return 0;
1006 }
1007 
1008 static const struct seq_operations dl_seq_ops_v1 = {
1009         .start = dl_seq_start,
1010         .next  = dl_seq_next,
1011         .stop  = dl_seq_stop,
1012         .show  = dl_seq_show_v1
1013 };
1014 
1015 static const struct seq_operations dl_seq_ops = {
1016         .start = dl_seq_start,
1017         .next  = dl_seq_next,
1018         .stop  = dl_seq_stop,
1019         .show  = dl_seq_show
1020 };
1021 
1022 static int dl_proc_open_v1(struct inode *inode, struct file *file)
1023 {
1024         int ret = seq_open(file, &dl_seq_ops_v1);
1025 
1026         if (!ret) {
1027                 struct seq_file *sf = file->private_data;
1028                 sf->private = PDE_DATA(inode);
1029         }
1030         return ret;
1031 }
1032 
1033 static int dl_proc_open(struct inode *inode, struct file *file)
1034 {
1035         int ret = seq_open(file, &dl_seq_ops);
1036 
1037         if (!ret) {
1038                 struct seq_file *sf = file->private_data;
1039 
1040                 sf->private = PDE_DATA(inode);
1041         }
1042         return ret;
1043 }
1044 
1045 static const struct file_operations dl_file_ops_v1 = {
1046         .owner   = THIS_MODULE,
1047         .open    = dl_proc_open_v1,
1048         .read    = seq_read,
1049         .llseek  = seq_lseek,
1050         .release = seq_release
1051 };
1052 
1053 static const struct file_operations dl_file_ops = {
1054         .owner   = THIS_MODULE,
1055         .open    = dl_proc_open,
1056         .read    = seq_read,
1057         .llseek  = seq_lseek,
1058         .release = seq_release
1059 };
1060 
1061 static int __net_init hashlimit_proc_net_init(struct net *net)
1062 {
1063         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1064 
1065         hashlimit_net->ipt_hashlimit = proc_mkdir("ipt_hashlimit", net->proc_net);
1066         if (!hashlimit_net->ipt_hashlimit)
1067                 return -ENOMEM;
1068 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1069         hashlimit_net->ip6t_hashlimit = proc_mkdir("ip6t_hashlimit", net->proc_net);
1070         if (!hashlimit_net->ip6t_hashlimit) {
1071                 remove_proc_entry("ipt_hashlimit", net->proc_net);
1072                 return -ENOMEM;
1073         }
1074 #endif
1075         return 0;
1076 }
1077 
1078 static void __net_exit hashlimit_proc_net_exit(struct net *net)
1079 {
1080         struct xt_hashlimit_htable *hinfo;
1081         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1082 
1083         /* hashlimit_net_exit() is called before hashlimit_mt_destroy().
1084          * Make sure that the parent ipt_hashlimit and ip6t_hashlimit proc
1085          * entries is empty before trying to remove it.
1086          */
1087         mutex_lock(&hashlimit_mutex);
1088         hlist_for_each_entry(hinfo, &hashlimit_net->htables, node)
1089                 htable_remove_proc_entry(hinfo);
1090         hashlimit_net->ipt_hashlimit = NULL;
1091         hashlimit_net->ip6t_hashlimit = NULL;
1092         mutex_unlock(&hashlimit_mutex);
1093 
1094         remove_proc_entry("ipt_hashlimit", net->proc_net);
1095 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1096         remove_proc_entry("ip6t_hashlimit", net->proc_net);
1097 #endif
1098 }
1099 
1100 static int __net_init hashlimit_net_init(struct net *net)
1101 {
1102         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1103 
1104         INIT_HLIST_HEAD(&hashlimit_net->htables);
1105         return hashlimit_proc_net_init(net);
1106 }
1107 
1108 static void __net_exit hashlimit_net_exit(struct net *net)
1109 {
1110         hashlimit_proc_net_exit(net);
1111 }
1112 
1113 static struct pernet_operations hashlimit_net_ops = {
1114         .init   = hashlimit_net_init,
1115         .exit   = hashlimit_net_exit,
1116         .id     = &hashlimit_net_id,
1117         .size   = sizeof(struct hashlimit_net),
1118 };
1119 
1120 static int __init hashlimit_mt_init(void)
1121 {
1122         int err;
1123 
1124         err = register_pernet_subsys(&hashlimit_net_ops);
1125         if (err < 0)
1126                 return err;
1127         err = xt_register_matches(hashlimit_mt_reg,
1128               ARRAY_SIZE(hashlimit_mt_reg));
1129         if (err < 0)
1130                 goto err1;
1131 
1132         err = -ENOMEM;
1133         hashlimit_cachep = kmem_cache_create("xt_hashlimit",
1134                                             sizeof(struct dsthash_ent), 0, 0,
1135                                             NULL);
1136         if (!hashlimit_cachep) {
1137                 pr_warn("unable to create slab cache\n");
1138                 goto err2;
1139         }
1140         return 0;
1141 
1142 err2:
1143         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
1144 err1:
1145         unregister_pernet_subsys(&hashlimit_net_ops);
1146         return err;
1147 
1148 }
1149 
1150 static void __exit hashlimit_mt_exit(void)
1151 {
1152         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
1153         unregister_pernet_subsys(&hashlimit_net_ops);
1154 
1155         rcu_barrier_bh();
1156         kmem_cache_destroy(hashlimit_cachep);
1157 }
1158 
1159 module_init(hashlimit_mt_init);
1160 module_exit(hashlimit_mt_exit);
1161 

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