net/ipv4/netfilter/ipt_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  * based on ipt_limit.c by:
  11  * Jérôme de Vivie      <devivie@info.enserb.u-bordeaux.fr>
  12  * Hervé Eychenne       <eychenne@info.enserb.u-bordeaux.fr>
  13  * Rusty Russell        <rusty@rustcorp.com.au>
  14  *
  15  * The general idea is to create a hash table for every dstip and have a
  16  * seperate limit counter per tuple.  This way you can do something like 'limit
  17  * the number of syn packets for each of my internal addresses.
  18  *
  19  * Ideally this would just be implemented as a general 'hash' match, which would
  20  * allow us to attach any iptables target to it's hash buckets.  But this is
  21  * not possible in the current iptables architecture.  As always, pkttables for
  22  * 2.7.x will help ;)
  23  */
  24 #include <linux/module.h>
  25 #include <linux/skbuff.h>
  26 #include <linux/spinlock.h>
  27 #include <linux/random.h>
  28 #include <linux/jhash.h>
  29 #include <linux/slab.h>
  30 #include <linux/vmalloc.h>
  31 #include <linux/proc_fs.h>
  32 #include <linux/seq_file.h>
  33 #include <linux/list.h>
  34
  35 #include <linux/netfilter_ipv4/ip_tables.h>
  36 #include <linux/netfilter_ipv4/ipt_hashlimit.h>
  37
  38 /* FIXME: this is just for IP_NF_ASSERRT */
  39 #include <linux/netfilter_ipv4/ip_conntrack.h>
  40 #include <linux/mutex.h>
  41
  42 MODULE_LICENSE("GPL");
  43 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  44 MODULE_DESCRIPTION("iptables match for limiting per hash-bucket");
  45
  46 /* need to declare this at the top */
  47 static struct proc_dir_entry *hashlimit_procdir;
  48 static struct file_operations dl_file_ops;
  49
  50 /* hash table crap */
  51
  52 struct dsthash_dst {
  53         __be32 src_ip;
  54         __be32 dst_ip;
  55         /* ports have to be consecutive !!! */
  56         __be16 src_port;
  57         __be16 dst_port;
  58 };
  59
  60 struct dsthash_ent {
  61         /* static / read-only parts in the beginning */
  62         struct hlist_node node;
  63         struct dsthash_dst dst;
  64
  65         /* modified structure members in the end */
  66         unsigned long expires;          /* precalculated expiry time */
  67         struct {
  68                 unsigned long prev;     /* last modification */
  69                 u_int32_t credit;
  70                 u_int32_t credit_cap, cost;
  71         } rateinfo;
  72 };
  73
  74 struct ipt_hashlimit_htable {
  75         struct hlist_node node;         /* global list of all htables */
  76         atomic_t use;
  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         struct timer_list timer;        /* timer for gc */
  85         atomic_t count;                 /* number entries in table */
  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 kmem_cache_t *hashlimit_cachep __read_mostly;
  97
  98 static inline int dst_cmp(const struct dsthash_ent *ent, struct dsthash_dst *b)
  99 {
 100         return (ent->dst.dst_ip == b->dst_ip
 101                 && ent->dst.dst_port == b->dst_port
 102                 && ent->dst.src_port == b->src_port
 103                 && ent->dst.src_ip == b->src_ip);
 104 }
 105
 106 static inline u_int32_t
 107 hash_dst(const struct ipt_hashlimit_htable *ht, const struct dsthash_dst *dst)
 108 {
 109         return (jhash_3words((__force u32)dst->dst_ip,
 110                             ((__force u32)dst->dst_port<<16 |
 111                              (__force u32)dst->src_port),
 112                              (__force u32)dst->src_ip, ht->rnd) % ht->cfg.size);
 113 }
 114
 115 static inline struct dsthash_ent *
 116 __dsthash_find(const struct ipt_hashlimit_htable *ht, struct dsthash_dst *dst)
 117 {
 118         struct dsthash_ent *ent;
 119         struct hlist_node *pos;
 120         u_int32_t hash = hash_dst(ht, dst);
 121
 122         if (!hlist_empty(&ht->hash[hash]))
 123                 hlist_for_each_entry(ent, pos, &ht->hash[hash], node) {
 124                         if (dst_cmp(ent, dst)) {
 125                                 return ent;
 126                         }
 127                 }
 128
 129         return NULL;
 130 }
 131
 132 /* allocate dsthash_ent, initialize dst, put in htable and lock it */
 133 static struct dsthash_ent *
 134 __dsthash_alloc_init(struct ipt_hashlimit_htable *ht, struct dsthash_dst *dst)
 135 {
 136         struct dsthash_ent *ent;
 137
 138         /* initialize hash with random val at the time we allocate
 139          * the first hashtable entry */
 140         if (!ht->rnd_initialized) {
 141                 get_random_bytes(&ht->rnd, 4);
 142                 ht->rnd_initialized = 1;
 143         }
 144
 145         if (ht->cfg.max &&
 146             atomic_read(&ht->count) >= ht->cfg.max) {
 147                 /* FIXME: do something. question is what.. */
 148                 if (net_ratelimit())
 149                         printk(KERN_WARNING
 150                                 "ipt_hashlimit: max count of %u reached\n",
 151                                 ht->cfg.max);
 152                 return NULL;
 153         }
 154
 155         ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
 156         if (!ent) {
 157                 if (net_ratelimit())
 158                         printk(KERN_ERR
 159                                 "ipt_hashlimit: can't allocate dsthash_ent\n");
 160                 return NULL;
 161         }
 162
 163         atomic_inc(&ht->count);
 164
 165         ent->dst.dst_ip = dst->dst_ip;
 166         ent->dst.dst_port = dst->dst_port;
 167         ent->dst.src_ip = dst->src_ip;
 168         ent->dst.src_port = dst->src_port;
 169
 170         hlist_add_head(&ent->node, &ht->hash[hash_dst(ht, dst)]);
 171
 172         return ent;
 173 }
 174
 175 static inline void
 176 __dsthash_free(struct ipt_hashlimit_htable *ht, struct dsthash_ent *ent)
 177 {
 178         hlist_del(&ent->node);
 179         kmem_cache_free(hashlimit_cachep, ent);
 180         atomic_dec(&ht->count);
 181 }
 182 static void htable_gc(unsigned long htlong);
 183
 184 static int htable_create(struct ipt_hashlimit_info *minfo)
 185 {
 186         int i;
 187         unsigned int size;
 188         struct ipt_hashlimit_htable *hinfo;
 189
 190         if (minfo->cfg.size)
 191                 size = minfo->cfg.size;
 192         else {
 193                 size = (((num_physpages << PAGE_SHIFT) / 16384)
 194                          / sizeof(struct list_head));
 195                 if (num_physpages > (1024 * 1024 * 1024 / PAGE_SIZE))
 196                         size = 8192;
 197                 if (size < 16)
 198                         size = 16;
 199         }
 200         /* FIXME: don't use vmalloc() here or anywhere else -HW */
 201         hinfo = vmalloc(sizeof(struct ipt_hashlimit_htable)
 202                         + (sizeof(struct list_head) * size));
 203         if (!hinfo) {
 204                 printk(KERN_ERR "ipt_hashlimit: Unable to create hashtable\n");
 205                 return -1;
 206         }
 207         minfo->hinfo = hinfo;
 208
 209         /* copy match config into hashtable config */
 210         memcpy(&hinfo->cfg, &minfo->cfg, sizeof(hinfo->cfg));
 211         hinfo->cfg.size = size;
 212         if (!hinfo->cfg.max)
 213                 hinfo->cfg.max = 8 * hinfo->cfg.size;
 214         else if (hinfo->cfg.max < hinfo->cfg.size)
 215                 hinfo->cfg.max = hinfo->cfg.size;
 216
 217         for (i = 0; i < hinfo->cfg.size; i++)
 218                 INIT_HLIST_HEAD(&hinfo->hash[i]);
 219
 220         atomic_set(&hinfo->count, 0);
 221         atomic_set(&hinfo->use, 1);
 222         hinfo->rnd_initialized = 0;
 223         spin_lock_init(&hinfo->lock);
 224         hinfo->pde = create_proc_entry(minfo->name, 0, hashlimit_procdir);
 225         if (!hinfo->pde) {
 226                 vfree(hinfo);
 227                 return -1;
 228         }
 229         hinfo->pde->proc_fops = &dl_file_ops;
 230         hinfo->pde->data = hinfo;
 231
 232         init_timer(&hinfo->timer);
 233         hinfo->timer.expires = jiffies + msecs_to_jiffies(hinfo->cfg.gc_interval);
 234         hinfo->timer.data = (unsigned long )hinfo;
 235         hinfo->timer.function = htable_gc;
 236         add_timer(&hinfo->timer);
 237
 238         spin_lock_bh(&hashlimit_lock);
 239         hlist_add_head(&hinfo->node, &hashlimit_htables);
 240         spin_unlock_bh(&hashlimit_lock);
 241
 242         return 0;
 243 }
 244
 245 static int select_all(struct ipt_hashlimit_htable *ht, struct dsthash_ent *he)
 246 {
 247         return 1;
 248 }
 249
 250 static int select_gc(struct ipt_hashlimit_htable *ht, struct dsthash_ent *he)
 251 {
 252         return (jiffies >= he->expires);
 253 }
 254
 255 static void htable_selective_cleanup(struct ipt_hashlimit_htable *ht,
 256                                 int (*select)(struct ipt_hashlimit_htable *ht,
 257                                               struct dsthash_ent *he))
 258 {
 259         int i;
 260
 261         IP_NF_ASSERT(ht->cfg.size && ht->cfg.max);
 262
 263         /* lock hash table and iterate over it */
 264         spin_lock_bh(&ht->lock);
 265         for (i = 0; i < ht->cfg.size; i++) {
 266                 struct dsthash_ent *dh;
 267                 struct hlist_node *pos, *n;
 268                 hlist_for_each_entry_safe(dh, pos, n, &ht->hash[i], node) {
 269                         if ((*select)(ht, dh))
 270                                 __dsthash_free(ht, dh);
 271                 }
 272         }
 273         spin_unlock_bh(&ht->lock);
 274 }
 275
 276 /* hash table garbage collector, run by timer */
 277 static void htable_gc(unsigned long htlong)
 278 {
 279         struct ipt_hashlimit_htable *ht = (struct ipt_hashlimit_htable *)htlong;
 280
 281         htable_selective_cleanup(ht, select_gc);
 282
 283         /* re-add the timer accordingly */
 284         ht->timer.expires = jiffies + msecs_to_jiffies(ht->cfg.gc_interval);
 285         add_timer(&ht->timer);
 286 }
 287
 288 static void htable_destroy(struct ipt_hashlimit_htable *hinfo)
 289 {
 290         /* remove timer, if it is pending */
 291         if (timer_pending(&hinfo->timer))
 292                 del_timer(&hinfo->timer);
 293
 294         /* remove proc entry */
 295         remove_proc_entry(hinfo->pde->name, hashlimit_procdir);
 296
 297         htable_selective_cleanup(hinfo, select_all);
 298         vfree(hinfo);
 299 }
 300
 301 static struct ipt_hashlimit_htable *htable_find_get(char *name)
 302 {
 303         struct ipt_hashlimit_htable *hinfo;
 304         struct hlist_node *pos;
 305
 306         spin_lock_bh(&hashlimit_lock);
 307         hlist_for_each_entry(hinfo, pos, &hashlimit_htables, node) {
 308                 if (!strcmp(name, hinfo->pde->name)) {
 309                         atomic_inc(&hinfo->use);
 310                         spin_unlock_bh(&hashlimit_lock);
 311                         return hinfo;
 312                 }
 313         }
 314         spin_unlock_bh(&hashlimit_lock);
 315
 316         return NULL;
 317 }
 318
 319 static void htable_put(struct ipt_hashlimit_htable *hinfo)
 320 {
 321         if (atomic_dec_and_test(&hinfo->use)) {
 322                 spin_lock_bh(&hashlimit_lock);
 323                 hlist_del(&hinfo->node);
 324                 spin_unlock_bh(&hashlimit_lock);
 325                 htable_destroy(hinfo);
 326         }
 327 }
 328
 329
 330 /* The algorithm used is the Simple Token Bucket Filter (TBF)
 331  * see net/sched/sch_tbf.c in the linux source tree
 332  */
 333
 334 /* Rusty: This is my (non-mathematically-inclined) understanding of
 335    this algorithm.  The `average rate' in jiffies becomes your initial
 336    amount of credit `credit' and the most credit you can ever have
 337    `credit_cap'.  The `peak rate' becomes the cost of passing the
 338    test, `cost'.
 339
 340    `prev' tracks the last packet hit: you gain one credit per jiffy.
 341    If you get credit balance more than this, the extra credit is
 342    discarded.  Every time the match passes, you lose `cost' credits;
 343    if you don't have that many, the test fails.
 344
 345    See Alexey's formal explanation in net/sched/sch_tbf.c.
 346
 347    To get the maximum range, we multiply by this factor (ie. you get N
 348    credits per jiffy).  We want to allow a rate as low as 1 per day
 349    (slowest userspace tool allows), which means
 350    CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
 351 */
 352 #define MAX_CPJ (0xFFFFFFFF / (HZ*60*60*24))
 353
 354 /* Repeated shift and or gives us all 1s, final shift and add 1 gives
 355  * us the power of 2 below the theoretical max, so GCC simply does a
 356  * shift. */
 357 #define _POW2_BELOW2(x) ((x)|((x)>>1))
 358 #define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
 359 #define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
 360 #define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
 361 #define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
 362 #define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
 363
 364 #define CREDITS_PER_JIFFY POW2_BELOW32(MAX_CPJ)
 365
 366 /* Precision saver. */
 367 static inline u_int32_t
 368 user2credits(u_int32_t user)
 369 {
 370         /* If multiplying would overflow... */
 371         if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY))
 372                 /* Divide first. */
 373                 return (user / IPT_HASHLIMIT_SCALE) * HZ * CREDITS_PER_JIFFY;
 374
 375         return (user * HZ * CREDITS_PER_JIFFY) / IPT_HASHLIMIT_SCALE;
 376 }
 377
 378 static inline void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now)
 379 {
 380         dh->rateinfo.credit += (now - xchg(&dh->rateinfo.prev, now))
 381                                         * CREDITS_PER_JIFFY;
 382         if (dh->rateinfo.credit > dh->rateinfo.credit_cap)
 383                 dh->rateinfo.credit = dh->rateinfo.credit_cap;
 384 }
 385
 386 static int
 387 hashlimit_match(const struct sk_buff *skb,
 388                 const struct net_device *in,
 389                 const struct net_device *out,
 390                 const struct xt_match *match,
 391                 const void *matchinfo,
 392                 int offset,
 393                 unsigned int protoff,
 394                 int *hotdrop)
 395 {
 396         struct ipt_hashlimit_info *r =
 397                 ((struct ipt_hashlimit_info *)matchinfo)->u.master;
 398         struct ipt_hashlimit_htable *hinfo = r->hinfo;
 399         unsigned long now = jiffies;
 400         struct dsthash_ent *dh;
 401         struct dsthash_dst dst;
 402
 403         /* build 'dst' according to hinfo->cfg and current packet */
 404         memset(&dst, 0, sizeof(dst));
 405         if (hinfo->cfg.mode & IPT_HASHLIMIT_HASH_DIP)
 406                 dst.dst_ip = skb->nh.iph->daddr;
 407         if (hinfo->cfg.mode & IPT_HASHLIMIT_HASH_SIP)
 408                 dst.src_ip = skb->nh.iph->saddr;
 409         if (hinfo->cfg.mode & IPT_HASHLIMIT_HASH_DPT
 410             ||hinfo->cfg.mode & IPT_HASHLIMIT_HASH_SPT) {
 411                 __be16 _ports[2], *ports;
 412
 413                 switch (skb->nh.iph->protocol) {
 414                 case IPPROTO_TCP:
 415                 case IPPROTO_UDP:
 416                 case IPPROTO_SCTP:
 417                 case IPPROTO_DCCP:
 418                         ports = skb_header_pointer(skb, skb->nh.iph->ihl*4,
 419                                                    sizeof(_ports), &_ports);
 420                         break;
 421                 default:
 422                         _ports[0] = _ports[1] = 0;
 423                         ports = _ports;
 424                         break;
 425                 }
 426                 if (!ports) {
 427                         /* We've been asked to examine this packet, and we
 428                           can't.  Hence, no choice but to drop. */
 429                         *hotdrop = 1;
 430                         return 0;
 431                 }
 432                 if (hinfo->cfg.mode & IPT_HASHLIMIT_HASH_SPT)
 433                         dst.src_port = ports[0];
 434                 if (hinfo->cfg.mode & IPT_HASHLIMIT_HASH_DPT)
 435                         dst.dst_port = ports[1];
 436         }
 437
 438         spin_lock_bh(&hinfo->lock);
 439         dh = __dsthash_find(hinfo, &dst);
 440         if (!dh) {
 441                 dh = __dsthash_alloc_init(hinfo, &dst);
 442
 443                 if (!dh) {
 444                         /* enomem... don't match == DROP */
 445                         if (net_ratelimit())
 446                                 printk(KERN_ERR "%s: ENOMEM\n", __FUNCTION__);
 447                         spin_unlock_bh(&hinfo->lock);
 448                         return 0;
 449                 }
 450
 451                 dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
 452
 453                 dh->rateinfo.prev = jiffies;
 454                 dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
 455                                                         hinfo->cfg.burst);
 456                 dh->rateinfo.credit_cap = user2credits(hinfo->cfg.avg *
 457                                                         hinfo->cfg.burst);
 458                 dh->rateinfo.cost = user2credits(hinfo->cfg.avg);
 459         } else {
 460                 /* update expiration timeout */
 461                 dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
 462                 rateinfo_recalc(dh, now);
 463         }
 464
 465         if (dh->rateinfo.credit >= dh->rateinfo.cost) {
 466                 /* We're underlimit. */
 467                 dh->rateinfo.credit -= dh->rateinfo.cost;
 468                 spin_unlock_bh(&hinfo->lock);
 469                 return 1;
 470         }
 471
 472         spin_unlock_bh(&hinfo->lock);
 473
 474         /* default case: we're overlimit, thus don't match */
 475         return 0;
 476 }
 477
 478 static int
 479 hashlimit_checkentry(const char *tablename,
 480                      const void *inf,
 481                      const struct xt_match *match,
 482                      void *matchinfo,
 483                      unsigned int hook_mask)
 484 {
 485         struct ipt_hashlimit_info *r = matchinfo;
 486
 487         /* Check for overflow. */
 488         if (r->cfg.burst == 0
 489             || user2credits(r->cfg.avg * r->cfg.burst) <
 490                                         user2credits(r->cfg.avg)) {
 491                 printk(KERN_ERR "ipt_hashlimit: Overflow, try lower: %u/%u\n",
 492                        r->cfg.avg, r->cfg.burst);
 493                 return 0;
 494         }
 495
 496         if (r->cfg.mode == 0
 497             || r->cfg.mode > (IPT_HASHLIMIT_HASH_DPT
 498                           |IPT_HASHLIMIT_HASH_DIP
 499                           |IPT_HASHLIMIT_HASH_SIP
 500                           |IPT_HASHLIMIT_HASH_SPT))
 501                 return 0;
 502
 503         if (!r->cfg.gc_interval)
 504                 return 0;
 505
 506         if (!r->cfg.expire)
 507                 return 0;
 508
 509         if (r->name[sizeof(r->name) - 1] != '\0')
 510                 return 0;
 511
 512         /* This is the best we've got: We cannot release and re-grab lock,
 513          * since checkentry() is called before ip_tables.c grabs ipt_mutex.
 514          * We also cannot grab the hashtable spinlock, since htable_create will
 515          * call vmalloc, and that can sleep.  And we cannot just re-search
 516          * the list of htable's in htable_create(), since then we would
 517          * create duplicate proc files. -HW */
 518         mutex_lock(&hlimit_mutex);
 519         r->hinfo = htable_find_get(r->name);
 520         if (!r->hinfo && (htable_create(r) != 0)) {
 521                 mutex_unlock(&hlimit_mutex);
 522                 return 0;
 523         }
 524         mutex_unlock(&hlimit_mutex);
 525
 526         /* Ugly hack: For SMP, we only want to use one set */
 527         r->u.master = r;
 528
 529         return 1;
 530 }
 531
 532 static void
 533 hashlimit_destroy(const struct xt_match *match, void *matchinfo)
 534 {
 535         struct ipt_hashlimit_info *r = matchinfo;
 536
 537         htable_put(r->hinfo);
 538 }
 539
 540 #ifdef CONFIG_COMPAT
 541 struct compat_ipt_hashlimit_info {
 542         char name[IFNAMSIZ];
 543         struct hashlimit_cfg cfg;
 544         compat_uptr_t hinfo;
 545         compat_uptr_t master;
 546 };
 547
 548 static void compat_from_user(void *dst, void *src)
 549 {
 550         int off = offsetof(struct compat_ipt_hashlimit_info, hinfo);
 551
 552         memcpy(dst, src, off);
 553         memset(dst + off, 0, sizeof(struct compat_ipt_hashlimit_info) - off);
 554 }
 555
 556 static int compat_to_user(void __user *dst, void *src)
 557 {
 558         int off = offsetof(struct compat_ipt_hashlimit_info, hinfo);
 559
 560         return copy_to_user(dst, src, off) ? -EFAULT : 0;
 561 }
 562 #endif
 563
 564 static struct ipt_match ipt_hashlimit = {
 565         .name           = "hashlimit",
 566         .match          = hashlimit_match,
 567         .matchsize      = sizeof(struct ipt_hashlimit_info),
 568 #ifdef CONFIG_COMPAT
 569         .compatsize     = sizeof(struct compat_ipt_hashlimit_info),
 570         .compat_from_user = compat_from_user,
 571         .compat_to_user = compat_to_user,
 572 #endif
 573         .checkentry     = hashlimit_checkentry,
 574         .destroy        = hashlimit_destroy,
 575         .me             = THIS_MODULE
 576 };
 577
 578 /* PROC stuff */
 579
 580 static void *dl_seq_start(struct seq_file *s, loff_t *pos)
 581 {
 582         struct proc_dir_entry *pde = s->private;
 583         struct ipt_hashlimit_htable *htable = pde->data;
 584         unsigned int *bucket;
 585
 586         spin_lock_bh(&htable->lock);
 587         if (*pos >= htable->cfg.size)
 588                 return NULL;
 589
 590         bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
 591         if (!bucket)
 592                 return ERR_PTR(-ENOMEM);
 593
 594         *bucket = *pos;
 595         return bucket;
 596 }
 597
 598 static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
 599 {
 600         struct proc_dir_entry *pde = s->private;
 601         struct ipt_hashlimit_htable *htable = pde->data;
 602         unsigned int *bucket = (unsigned int *)v;
 603
 604         *pos = ++(*bucket);
 605         if (*pos >= htable->cfg.size) {
 606                 kfree(v);
 607                 return NULL;
 608         }
 609         return bucket;
 610 }
 611
 612 static void dl_seq_stop(struct seq_file *s, void *v)
 613 {
 614         struct proc_dir_entry *pde = s->private;
 615         struct ipt_hashlimit_htable *htable = pde->data;
 616         unsigned int *bucket = (unsigned int *)v;
 617
 618         kfree(bucket);
 619
 620         spin_unlock_bh(&htable->lock);
 621 }
 622
 623 static inline int dl_seq_real_show(struct dsthash_ent *ent, struct seq_file *s)
 624 {
 625         /* recalculate to show accurate numbers */
 626         rateinfo_recalc(ent, jiffies);
 627
 628         return seq_printf(s, "%ld %u.%u.%u.%u:%u->%u.%u.%u.%u:%u %u %u %u\n",
 629                         (long)(ent->expires - jiffies)/HZ,
 630                         NIPQUAD(ent->dst.src_ip), ntohs(ent->dst.src_port),
 631                         NIPQUAD(ent->dst.dst_ip), ntohs(ent->dst.dst_port),
 632                         ent->rateinfo.credit, ent->rateinfo.credit_cap,
 633                         ent->rateinfo.cost);
 634 }
 635
 636 static int dl_seq_show(struct seq_file *s, void *v)
 637 {
 638         struct proc_dir_entry *pde = s->private;
 639         struct ipt_hashlimit_htable *htable = pde->data;
 640         unsigned int *bucket = (unsigned int *)v;
 641         struct dsthash_ent *ent;
 642         struct hlist_node *pos;
 643
 644         if (!hlist_empty(&htable->hash[*bucket]))
 645                 hlist_for_each_entry(ent, pos, &htable->hash[*bucket], node) {
 646                         if (dl_seq_real_show(ent, s)) {
 647                                 /* buffer was filled and unable to print that tuple */
 648                                 return 1;
 649                         }
 650                 }
 651
 652         return 0;
 653 }
 654
 655 static struct seq_operations dl_seq_ops = {
 656         .start = dl_seq_start,
 657         .next  = dl_seq_next,
 658         .stop  = dl_seq_stop,
 659         .show  = dl_seq_show
 660 };
 661
 662 static int dl_proc_open(struct inode *inode, struct file *file)
 663 {
 664         int ret = seq_open(file, &dl_seq_ops);
 665
 666         if (!ret) {
 667                 struct seq_file *sf = file->private_data;
 668                 sf->private = PDE(inode);
 669         }
 670         return ret;
 671 }
 672
 673 static struct file_operations dl_file_ops = {
 674         .owner   = THIS_MODULE,
 675         .open    = dl_proc_open,
 676         .read    = seq_read,
 677         .llseek  = seq_lseek,
 678         .release = seq_release
 679 };
 680
 681 static int init_or_fini(int fini)
 682 {
 683         int ret = 0;
 684
 685         if (fini)
 686                 goto cleanup;
 687
 688         if (ipt_register_match(&ipt_hashlimit)) {
 689                 ret = -EINVAL;
 690                 goto cleanup_nothing;
 691         }
 692
 693         hashlimit_cachep = kmem_cache_create("ipt_hashlimit",
 694                                             sizeof(struct dsthash_ent), 0,
 695                                             0, NULL, NULL);
 696         if (!hashlimit_cachep) {
 697                 printk(KERN_ERR "Unable to create ipt_hashlimit slab cache\n");
 698                 ret = -ENOMEM;
 699                 goto cleanup_unreg_match;
 700         }
 701
 702         hashlimit_procdir = proc_mkdir("ipt_hashlimit", proc_net);
 703         if (!hashlimit_procdir) {
 704                 printk(KERN_ERR "Unable to create proc dir entry\n");
 705                 ret = -ENOMEM;
 706                 goto cleanup_free_slab;
 707         }
 708
 709         return ret;
 710
 711 cleanup:
 712         remove_proc_entry("ipt_hashlimit", proc_net);
 713 cleanup_free_slab:
 714         kmem_cache_destroy(hashlimit_cachep);
 715 cleanup_unreg_match:
 716         ipt_unregister_match(&ipt_hashlimit);
 717 cleanup_nothing:
 718         return ret;
 719
 720 }
 721
 722 static int __init ipt_hashlimit_init(void)
 723 {
 724         return init_or_fini(0);
 725 }
 726
 727 static void __exit ipt_hashlimit_fini(void)
 728 {
 729         init_or_fini(1);
 730 }
 731
 732 module_init(ipt_hashlimit_init);
 733 module_exit(ipt_hashlimit_fini);