Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/shaggy...
[linux-2.6] / net / netfilter / xt_hashlimit.c
1 /* iptables match extension to limit the number of packets per second
2  * seperately for each hashbucket (sourceip/sourceport/dstip/dstport)
3  *
4  * (C) 2003-2004 by Harald Welte <laforge@netfilter.org>
5  *
6  * $Id: ipt_hashlimit.c 3244 2004-10-20 16:24:29Z laforge@netfilter.org $
7  *
8  * Development of this code was funded by Astaro AG, http://www.astaro.com/
9  */
10 #include <linux/module.h>
11 #include <linux/spinlock.h>
12 #include <linux/random.h>
13 #include <linux/jhash.h>
14 #include <linux/slab.h>
15 #include <linux/vmalloc.h>
16 #include <linux/proc_fs.h>
17 #include <linux/seq_file.h>
18 #include <linux/list.h>
19 #include <linux/skbuff.h>
20 #include <linux/mm.h>
21 #include <linux/in.h>
22 #include <linux/ip.h>
23 #include <linux/ipv6.h>
24 #include <net/net_namespace.h>
25
26 #include <linux/netfilter/x_tables.h>
27 #include <linux/netfilter_ipv4/ip_tables.h>
28 #include <linux/netfilter_ipv6/ip6_tables.h>
29 #include <linux/netfilter/xt_hashlimit.h>
30 #include <linux/mutex.h>
31
32 MODULE_LICENSE("GPL");
33 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
34 MODULE_DESCRIPTION("iptables match for limiting per hash-bucket");
35 MODULE_ALIAS("ipt_hashlimit");
36 MODULE_ALIAS("ip6t_hashlimit");
37
38 /* need to declare this at the top */
39 static struct proc_dir_entry *hashlimit_procdir4;
40 static struct proc_dir_entry *hashlimit_procdir6;
41 static const struct file_operations dl_file_ops;
42
43 /* hash table crap */
44 struct dsthash_dst {
45         union {
46                 struct {
47                         __be32 src;
48                         __be32 dst;
49                 } ip;
50                 struct {
51                         __be32 src[4];
52                         __be32 dst[4];
53                 } ip6;
54         } addr;
55         __be16 src_port;
56         __be16 dst_port;
57 };
58
59 struct dsthash_ent {
60         /* static / read-only parts in the beginning */
61         struct hlist_node node;
62         struct dsthash_dst dst;
63
64         /* modified structure members in the end */
65         unsigned long expires;          /* precalculated expiry time */
66         struct {
67                 unsigned long prev;     /* last modification */
68                 u_int32_t credit;
69                 u_int32_t credit_cap, cost;
70         } rateinfo;
71 };
72
73 struct xt_hashlimit_htable {
74         struct hlist_node node;         /* global list of all htables */
75         atomic_t use;
76         int family;
77
78         struct hashlimit_cfg cfg;       /* config */
79
80         /* used internally */
81         spinlock_t lock;                /* lock for list_head */
82         u_int32_t rnd;                  /* random seed for hash */
83         int rnd_initialized;
84         unsigned int count;             /* number entries in table */
85         struct timer_list timer;        /* timer for gc */
86
87         /* seq_file stuff */
88         struct proc_dir_entry *pde;
89
90         struct hlist_head hash[0];      /* hashtable itself */
91 };
92
93 static DEFINE_SPINLOCK(hashlimit_lock); /* protects htables list */
94 static DEFINE_MUTEX(hlimit_mutex);      /* additional checkentry protection */
95 static HLIST_HEAD(hashlimit_htables);
96 static struct kmem_cache *hashlimit_cachep __read_mostly;
97
98 static inline bool dst_cmp(const struct dsthash_ent *ent,
99                            const struct dsthash_dst *b)
100 {
101         return !memcmp(&ent->dst, b, sizeof(ent->dst));
102 }
103
104 static u_int32_t
105 hash_dst(const struct xt_hashlimit_htable *ht, const struct dsthash_dst *dst)
106 {
107         return jhash(dst, sizeof(*dst), ht->rnd) % ht->cfg.size;
108 }
109
110 static struct dsthash_ent *
111 dsthash_find(const struct xt_hashlimit_htable *ht,
112              const struct dsthash_dst *dst)
113 {
114         struct dsthash_ent *ent;
115         struct hlist_node *pos;
116         u_int32_t hash = hash_dst(ht, dst);
117
118         if (!hlist_empty(&ht->hash[hash])) {
119                 hlist_for_each_entry(ent, pos, &ht->hash[hash], node)
120                         if (dst_cmp(ent, dst))
121                                 return ent;
122         }
123         return NULL;
124 }
125
126 /* allocate dsthash_ent, initialize dst, put in htable and lock it */
127 static struct dsthash_ent *
128 dsthash_alloc_init(struct xt_hashlimit_htable *ht,
129                    const struct dsthash_dst *dst)
130 {
131         struct dsthash_ent *ent;
132
133         /* initialize hash with random val at the time we allocate
134          * the first hashtable entry */
135         if (!ht->rnd_initialized) {
136                 get_random_bytes(&ht->rnd, 4);
137                 ht->rnd_initialized = 1;
138         }
139
140         if (ht->cfg.max && ht->count >= ht->cfg.max) {
141                 /* FIXME: do something. question is what.. */
142                 if (net_ratelimit())
143                         printk(KERN_WARNING
144                                 "xt_hashlimit: max count of %u reached\n",
145                                 ht->cfg.max);
146                 return NULL;
147         }
148
149         ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
150         if (!ent) {
151                 if (net_ratelimit())
152                         printk(KERN_ERR
153                                 "xt_hashlimit: can't allocate dsthash_ent\n");
154                 return NULL;
155         }
156         memcpy(&ent->dst, dst, sizeof(ent->dst));
157
158         hlist_add_head(&ent->node, &ht->hash[hash_dst(ht, dst)]);
159         ht->count++;
160         return ent;
161 }
162
163 static inline void
164 dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent)
165 {
166         hlist_del(&ent->node);
167         kmem_cache_free(hashlimit_cachep, ent);
168         ht->count--;
169 }
170 static void htable_gc(unsigned long htlong);
171
172 static int htable_create(struct xt_hashlimit_info *minfo, int family)
173 {
174         struct xt_hashlimit_htable *hinfo;
175         unsigned int size;
176         unsigned int i;
177
178         if (minfo->cfg.size)
179                 size = minfo->cfg.size;
180         else {
181                 size = ((num_physpages << PAGE_SHIFT) / 16384) /
182                        sizeof(struct list_head);
183                 if (num_physpages > (1024 * 1024 * 1024 / PAGE_SIZE))
184                         size = 8192;
185                 if (size < 16)
186                         size = 16;
187         }
188         /* FIXME: don't use vmalloc() here or anywhere else -HW */
189         hinfo = vmalloc(sizeof(struct xt_hashlimit_htable) +
190                         sizeof(struct list_head) * size);
191         if (!hinfo) {
192                 printk(KERN_ERR "xt_hashlimit: unable to create hashtable\n");
193                 return -1;
194         }
195         minfo->hinfo = hinfo;
196
197         /* copy match config into hashtable config */
198         memcpy(&hinfo->cfg, &minfo->cfg, sizeof(hinfo->cfg));
199         hinfo->cfg.size = size;
200         if (!hinfo->cfg.max)
201                 hinfo->cfg.max = 8 * hinfo->cfg.size;
202         else if (hinfo->cfg.max < hinfo->cfg.size)
203                 hinfo->cfg.max = hinfo->cfg.size;
204
205         for (i = 0; i < hinfo->cfg.size; i++)
206                 INIT_HLIST_HEAD(&hinfo->hash[i]);
207
208         atomic_set(&hinfo->use, 1);
209         hinfo->count = 0;
210         hinfo->family = family;
211         hinfo->rnd_initialized = 0;
212         spin_lock_init(&hinfo->lock);
213         hinfo->pde = create_proc_entry(minfo->name, 0,
214                                        family == AF_INET ? hashlimit_procdir4 :
215                                                            hashlimit_procdir6);
216         if (!hinfo->pde) {
217                 vfree(hinfo);
218                 return -1;
219         }
220         hinfo->pde->proc_fops = &dl_file_ops;
221         hinfo->pde->data = hinfo;
222
223         setup_timer(&hinfo->timer, htable_gc, (unsigned long )hinfo);
224         hinfo->timer.expires = jiffies + msecs_to_jiffies(hinfo->cfg.gc_interval);
225         add_timer(&hinfo->timer);
226
227         spin_lock_bh(&hashlimit_lock);
228         hlist_add_head(&hinfo->node, &hashlimit_htables);
229         spin_unlock_bh(&hashlimit_lock);
230
231         return 0;
232 }
233
234 static bool select_all(const struct xt_hashlimit_htable *ht,
235                        const struct dsthash_ent *he)
236 {
237         return 1;
238 }
239
240 static bool select_gc(const struct xt_hashlimit_htable *ht,
241                       const struct dsthash_ent *he)
242 {
243         return time_after_eq(jiffies, he->expires);
244 }
245
246 static void htable_selective_cleanup(struct xt_hashlimit_htable *ht,
247                         bool (*select)(const struct xt_hashlimit_htable *ht,
248                                       const struct dsthash_ent *he))
249 {
250         unsigned int i;
251
252         /* lock hash table and iterate over it */
253         spin_lock_bh(&ht->lock);
254         for (i = 0; i < ht->cfg.size; i++) {
255                 struct dsthash_ent *dh;
256                 struct hlist_node *pos, *n;
257                 hlist_for_each_entry_safe(dh, pos, n, &ht->hash[i], node) {
258                         if ((*select)(ht, dh))
259                                 dsthash_free(ht, dh);
260                 }
261         }
262         spin_unlock_bh(&ht->lock);
263 }
264
265 /* hash table garbage collector, run by timer */
266 static void htable_gc(unsigned long htlong)
267 {
268         struct xt_hashlimit_htable *ht = (struct xt_hashlimit_htable *)htlong;
269
270         htable_selective_cleanup(ht, select_gc);
271
272         /* re-add the timer accordingly */
273         ht->timer.expires = jiffies + msecs_to_jiffies(ht->cfg.gc_interval);
274         add_timer(&ht->timer);
275 }
276
277 static void htable_destroy(struct xt_hashlimit_htable *hinfo)
278 {
279         /* remove timer, if it is pending */
280         if (timer_pending(&hinfo->timer))
281                 del_timer(&hinfo->timer);
282
283         /* remove proc entry */
284         remove_proc_entry(hinfo->pde->name,
285                           hinfo->family == AF_INET ? hashlimit_procdir4 :
286                                                      hashlimit_procdir6);
287         htable_selective_cleanup(hinfo, select_all);
288         vfree(hinfo);
289 }
290
291 static struct xt_hashlimit_htable *htable_find_get(const char *name,
292                                                    int family)
293 {
294         struct xt_hashlimit_htable *hinfo;
295         struct hlist_node *pos;
296
297         spin_lock_bh(&hashlimit_lock);
298         hlist_for_each_entry(hinfo, pos, &hashlimit_htables, node) {
299                 if (!strcmp(name, hinfo->pde->name) &&
300                     hinfo->family == family) {
301                         atomic_inc(&hinfo->use);
302                         spin_unlock_bh(&hashlimit_lock);
303                         return hinfo;
304                 }
305         }
306         spin_unlock_bh(&hashlimit_lock);
307         return NULL;
308 }
309
310 static void htable_put(struct xt_hashlimit_htable *hinfo)
311 {
312         if (atomic_dec_and_test(&hinfo->use)) {
313                 spin_lock_bh(&hashlimit_lock);
314                 hlist_del(&hinfo->node);
315                 spin_unlock_bh(&hashlimit_lock);
316                 htable_destroy(hinfo);
317         }
318 }
319
320 /* The algorithm used is the Simple Token Bucket Filter (TBF)
321  * see net/sched/sch_tbf.c in the linux source tree
322  */
323
324 /* Rusty: This is my (non-mathematically-inclined) understanding of
325    this algorithm.  The `average rate' in jiffies becomes your initial
326    amount of credit `credit' and the most credit you can ever have
327    `credit_cap'.  The `peak rate' becomes the cost of passing the
328    test, `cost'.
329
330    `prev' tracks the last packet hit: you gain one credit per jiffy.
331    If you get credit balance more than this, the extra credit is
332    discarded.  Every time the match passes, you lose `cost' credits;
333    if you don't have that many, the test fails.
334
335    See Alexey's formal explanation in net/sched/sch_tbf.c.
336
337    To get the maximum range, we multiply by this factor (ie. you get N
338    credits per jiffy).  We want to allow a rate as low as 1 per day
339    (slowest userspace tool allows), which means
340    CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
341 */
342 #define MAX_CPJ (0xFFFFFFFF / (HZ*60*60*24))
343
344 /* Repeated shift and or gives us all 1s, final shift and add 1 gives
345  * us the power of 2 below the theoretical max, so GCC simply does a
346  * shift. */
347 #define _POW2_BELOW2(x) ((x)|((x)>>1))
348 #define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
349 #define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
350 #define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
351 #define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
352 #define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
353
354 #define CREDITS_PER_JIFFY POW2_BELOW32(MAX_CPJ)
355
356 /* Precision saver. */
357 static inline u_int32_t
358 user2credits(u_int32_t user)
359 {
360         /* If multiplying would overflow... */
361         if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY))
362                 /* Divide first. */
363                 return (user / XT_HASHLIMIT_SCALE) * HZ * CREDITS_PER_JIFFY;
364
365         return (user * HZ * CREDITS_PER_JIFFY) / XT_HASHLIMIT_SCALE;
366 }
367
368 static inline void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now)
369 {
370         dh->rateinfo.credit += (now - dh->rateinfo.prev) * CREDITS_PER_JIFFY;
371         if (dh->rateinfo.credit > dh->rateinfo.credit_cap)
372                 dh->rateinfo.credit = dh->rateinfo.credit_cap;
373         dh->rateinfo.prev = now;
374 }
375
376 static int
377 hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
378                    struct dsthash_dst *dst,
379                    const struct sk_buff *skb, unsigned int protoff)
380 {
381         __be16 _ports[2], *ports;
382         int nexthdr;
383
384         memset(dst, 0, sizeof(*dst));
385
386         switch (hinfo->family) {
387         case AF_INET:
388                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
389                         dst->addr.ip.dst = ip_hdr(skb)->daddr;
390                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
391                         dst->addr.ip.src = ip_hdr(skb)->saddr;
392
393                 if (!(hinfo->cfg.mode &
394                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
395                         return 0;
396                 nexthdr = ip_hdr(skb)->protocol;
397                 break;
398 #if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
399         case AF_INET6:
400                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
401                         memcpy(&dst->addr.ip6.dst, &ipv6_hdr(skb)->daddr,
402                                sizeof(dst->addr.ip6.dst));
403                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
404                         memcpy(&dst->addr.ip6.src, &ipv6_hdr(skb)->saddr,
405                                sizeof(dst->addr.ip6.src));
406
407                 if (!(hinfo->cfg.mode &
408                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
409                         return 0;
410                 nexthdr = ipv6_find_hdr(skb, &protoff, -1, NULL);
411                 if (nexthdr < 0)
412                         return -1;
413                 break;
414 #endif
415         default:
416                 BUG();
417                 return 0;
418         }
419
420         switch (nexthdr) {
421         case IPPROTO_TCP:
422         case IPPROTO_UDP:
423         case IPPROTO_UDPLITE:
424         case IPPROTO_SCTP:
425         case IPPROTO_DCCP:
426                 ports = skb_header_pointer(skb, protoff, sizeof(_ports),
427                                            &_ports);
428                 break;
429         default:
430                 _ports[0] = _ports[1] = 0;
431                 ports = _ports;
432                 break;
433         }
434         if (!ports)
435                 return -1;
436         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT)
437                 dst->src_port = ports[0];
438         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT)
439                 dst->dst_port = ports[1];
440         return 0;
441 }
442
443 static bool
444 hashlimit_match(const struct sk_buff *skb,
445                 const struct net_device *in,
446                 const struct net_device *out,
447                 const struct xt_match *match,
448                 const void *matchinfo,
449                 int offset,
450                 unsigned int protoff,
451                 bool *hotdrop)
452 {
453         const struct xt_hashlimit_info *r =
454                 ((const struct xt_hashlimit_info *)matchinfo)->u.master;
455         struct xt_hashlimit_htable *hinfo = r->hinfo;
456         unsigned long now = jiffies;
457         struct dsthash_ent *dh;
458         struct dsthash_dst dst;
459
460         if (hashlimit_init_dst(hinfo, &dst, skb, protoff) < 0)
461                 goto hotdrop;
462
463         spin_lock_bh(&hinfo->lock);
464         dh = dsthash_find(hinfo, &dst);
465         if (!dh) {
466                 dh = dsthash_alloc_init(hinfo, &dst);
467                 if (!dh) {
468                         spin_unlock_bh(&hinfo->lock);
469                         goto hotdrop;
470                 }
471
472                 dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
473                 dh->rateinfo.prev = jiffies;
474                 dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
475                                                    hinfo->cfg.burst);
476                 dh->rateinfo.credit_cap = user2credits(hinfo->cfg.avg *
477                                                        hinfo->cfg.burst);
478                 dh->rateinfo.cost = user2credits(hinfo->cfg.avg);
479         } else {
480                 /* update expiration timeout */
481                 dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
482                 rateinfo_recalc(dh, now);
483         }
484
485         if (dh->rateinfo.credit >= dh->rateinfo.cost) {
486                 /* We're underlimit. */
487                 dh->rateinfo.credit -= dh->rateinfo.cost;
488                 spin_unlock_bh(&hinfo->lock);
489                 return true;
490         }
491
492         spin_unlock_bh(&hinfo->lock);
493
494         /* default case: we're overlimit, thus don't match */
495         return false;
496
497 hotdrop:
498         *hotdrop = true;
499         return false;
500 }
501
502 static bool
503 hashlimit_checkentry(const char *tablename,
504                      const void *inf,
505                      const struct xt_match *match,
506                      void *matchinfo,
507                      unsigned int hook_mask)
508 {
509         struct xt_hashlimit_info *r = matchinfo;
510
511         /* Check for overflow. */
512         if (r->cfg.burst == 0 ||
513             user2credits(r->cfg.avg * r->cfg.burst) < user2credits(r->cfg.avg)) {
514                 printk(KERN_ERR "xt_hashlimit: overflow, try lower: %u/%u\n",
515                        r->cfg.avg, r->cfg.burst);
516                 return false;
517         }
518         if (r->cfg.mode == 0 ||
519             r->cfg.mode > (XT_HASHLIMIT_HASH_DPT |
520                            XT_HASHLIMIT_HASH_DIP |
521                            XT_HASHLIMIT_HASH_SIP |
522                            XT_HASHLIMIT_HASH_SPT))
523                 return false;
524         if (!r->cfg.gc_interval)
525                 return false;
526         if (!r->cfg.expire)
527                 return false;
528         if (r->name[sizeof(r->name) - 1] != '\0')
529                 return false;
530
531         /* This is the best we've got: We cannot release and re-grab lock,
532          * since checkentry() is called before x_tables.c grabs xt_mutex.
533          * We also cannot grab the hashtable spinlock, since htable_create will
534          * call vmalloc, and that can sleep.  And we cannot just re-search
535          * the list of htable's in htable_create(), since then we would
536          * create duplicate proc files. -HW */
537         mutex_lock(&hlimit_mutex);
538         r->hinfo = htable_find_get(r->name, match->family);
539         if (!r->hinfo && htable_create(r, match->family) != 0) {
540                 mutex_unlock(&hlimit_mutex);
541                 return false;
542         }
543         mutex_unlock(&hlimit_mutex);
544
545         /* Ugly hack: For SMP, we only want to use one set */
546         r->u.master = r;
547         return true;
548 }
549
550 static void
551 hashlimit_destroy(const struct xt_match *match, void *matchinfo)
552 {
553         const struct xt_hashlimit_info *r = matchinfo;
554
555         htable_put(r->hinfo);
556 }
557
558 #ifdef CONFIG_COMPAT
559 struct compat_xt_hashlimit_info {
560         char name[IFNAMSIZ];
561         struct hashlimit_cfg cfg;
562         compat_uptr_t hinfo;
563         compat_uptr_t master;
564 };
565
566 static void compat_from_user(void *dst, void *src)
567 {
568         int off = offsetof(struct compat_xt_hashlimit_info, hinfo);
569
570         memcpy(dst, src, off);
571         memset(dst + off, 0, sizeof(struct compat_xt_hashlimit_info) - off);
572 }
573
574 static int compat_to_user(void __user *dst, void *src)
575 {
576         int off = offsetof(struct compat_xt_hashlimit_info, hinfo);
577
578         return copy_to_user(dst, src, off) ? -EFAULT : 0;
579 }
580 #endif
581
582 static struct xt_match xt_hashlimit[] __read_mostly = {
583         {
584                 .name           = "hashlimit",
585                 .family         = AF_INET,
586                 .match          = hashlimit_match,
587                 .matchsize      = sizeof(struct xt_hashlimit_info),
588 #ifdef CONFIG_COMPAT
589                 .compatsize     = sizeof(struct compat_xt_hashlimit_info),
590                 .compat_from_user = compat_from_user,
591                 .compat_to_user = compat_to_user,
592 #endif
593                 .checkentry     = hashlimit_checkentry,
594                 .destroy        = hashlimit_destroy,
595                 .me             = THIS_MODULE
596         },
597         {
598                 .name           = "hashlimit",
599                 .family         = AF_INET6,
600                 .match          = hashlimit_match,
601                 .matchsize      = sizeof(struct xt_hashlimit_info),
602 #ifdef CONFIG_COMPAT
603                 .compatsize     = sizeof(struct compat_xt_hashlimit_info),
604                 .compat_from_user = compat_from_user,
605                 .compat_to_user = compat_to_user,
606 #endif
607                 .checkentry     = hashlimit_checkentry,
608                 .destroy        = hashlimit_destroy,
609                 .me             = THIS_MODULE
610         },
611 };
612
613 /* PROC stuff */
614 static void *dl_seq_start(struct seq_file *s, loff_t *pos)
615 {
616         struct proc_dir_entry *pde = s->private;
617         struct xt_hashlimit_htable *htable = pde->data;
618         unsigned int *bucket;
619
620         spin_lock_bh(&htable->lock);
621         if (*pos >= htable->cfg.size)
622                 return NULL;
623
624         bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
625         if (!bucket)
626                 return ERR_PTR(-ENOMEM);
627
628         *bucket = *pos;
629         return bucket;
630 }
631
632 static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
633 {
634         struct proc_dir_entry *pde = s->private;
635         struct xt_hashlimit_htable *htable = pde->data;
636         unsigned int *bucket = (unsigned int *)v;
637
638         *pos = ++(*bucket);
639         if (*pos >= htable->cfg.size) {
640                 kfree(v);
641                 return NULL;
642         }
643         return bucket;
644 }
645
646 static void dl_seq_stop(struct seq_file *s, void *v)
647 {
648         struct proc_dir_entry *pde = s->private;
649         struct xt_hashlimit_htable *htable = pde->data;
650         unsigned int *bucket = (unsigned int *)v;
651
652         kfree(bucket);
653         spin_unlock_bh(&htable->lock);
654 }
655
656 static int dl_seq_real_show(struct dsthash_ent *ent, int family,
657                                    struct seq_file *s)
658 {
659         /* recalculate to show accurate numbers */
660         rateinfo_recalc(ent, jiffies);
661
662         switch (family) {
663         case AF_INET:
664                 return seq_printf(s, "%ld %u.%u.%u.%u:%u->"
665                                      "%u.%u.%u.%u:%u %u %u %u\n",
666                                  (long)(ent->expires - jiffies)/HZ,
667                                  NIPQUAD(ent->dst.addr.ip.src),
668                                  ntohs(ent->dst.src_port),
669                                  NIPQUAD(ent->dst.addr.ip.dst),
670                                  ntohs(ent->dst.dst_port),
671                                  ent->rateinfo.credit, ent->rateinfo.credit_cap,
672                                  ent->rateinfo.cost);
673         case AF_INET6:
674                 return seq_printf(s, "%ld " NIP6_FMT ":%u->"
675                                      NIP6_FMT ":%u %u %u %u\n",
676                                  (long)(ent->expires - jiffies)/HZ,
677                                  NIP6(*(struct in6_addr *)&ent->dst.addr.ip6.src),
678                                  ntohs(ent->dst.src_port),
679                                  NIP6(*(struct in6_addr *)&ent->dst.addr.ip6.dst),
680                                  ntohs(ent->dst.dst_port),
681                                  ent->rateinfo.credit, ent->rateinfo.credit_cap,
682                                  ent->rateinfo.cost);
683         default:
684                 BUG();
685                 return 0;
686         }
687 }
688
689 static int dl_seq_show(struct seq_file *s, void *v)
690 {
691         struct proc_dir_entry *pde = s->private;
692         struct xt_hashlimit_htable *htable = pde->data;
693         unsigned int *bucket = (unsigned int *)v;
694         struct dsthash_ent *ent;
695         struct hlist_node *pos;
696
697         if (!hlist_empty(&htable->hash[*bucket])) {
698                 hlist_for_each_entry(ent, pos, &htable->hash[*bucket], node)
699                         if (dl_seq_real_show(ent, htable->family, s))
700                                 return 1;
701         }
702         return 0;
703 }
704
705 static const struct seq_operations dl_seq_ops = {
706         .start = dl_seq_start,
707         .next  = dl_seq_next,
708         .stop  = dl_seq_stop,
709         .show  = dl_seq_show
710 };
711
712 static int dl_proc_open(struct inode *inode, struct file *file)
713 {
714         int ret = seq_open(file, &dl_seq_ops);
715
716         if (!ret) {
717                 struct seq_file *sf = file->private_data;
718                 sf->private = PDE(inode);
719         }
720         return ret;
721 }
722
723 static const struct file_operations dl_file_ops = {
724         .owner   = THIS_MODULE,
725         .open    = dl_proc_open,
726         .read    = seq_read,
727         .llseek  = seq_lseek,
728         .release = seq_release
729 };
730
731 static int __init xt_hashlimit_init(void)
732 {
733         int err;
734
735         err = xt_register_matches(xt_hashlimit, ARRAY_SIZE(xt_hashlimit));
736         if (err < 0)
737                 goto err1;
738
739         err = -ENOMEM;
740         hashlimit_cachep = kmem_cache_create("xt_hashlimit",
741                                             sizeof(struct dsthash_ent), 0, 0,
742                                             NULL);
743         if (!hashlimit_cachep) {
744                 printk(KERN_ERR "xt_hashlimit: unable to create slab cache\n");
745                 goto err2;
746         }
747         hashlimit_procdir4 = proc_mkdir("ipt_hashlimit", init_net.proc_net);
748         if (!hashlimit_procdir4) {
749                 printk(KERN_ERR "xt_hashlimit: unable to create proc dir "
750                                 "entry\n");
751                 goto err3;
752         }
753         hashlimit_procdir6 = proc_mkdir("ip6t_hashlimit", init_net.proc_net);
754         if (!hashlimit_procdir6) {
755                 printk(KERN_ERR "xt_hashlimit: unable to create proc dir "
756                                 "entry\n");
757                 goto err4;
758         }
759         return 0;
760 err4:
761         remove_proc_entry("ipt_hashlimit", init_net.proc_net);
762 err3:
763         kmem_cache_destroy(hashlimit_cachep);
764 err2:
765         xt_unregister_matches(xt_hashlimit, ARRAY_SIZE(xt_hashlimit));
766 err1:
767         return err;
768
769 }
770
771 static void __exit xt_hashlimit_fini(void)
772 {
773         remove_proc_entry("ipt_hashlimit", init_net.proc_net);
774         remove_proc_entry("ip6t_hashlimit", init_net.proc_net);
775         kmem_cache_destroy(hashlimit_cachep);
776         xt_unregister_matches(xt_hashlimit, ARRAY_SIZE(xt_hashlimit));
777 }
778
779 module_init(xt_hashlimit_init);
780 module_exit(xt_hashlimit_fini);