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
  25 #include <linux/netfilter/x_tables.h>
  26 #include <linux/netfilter_ipv4/ip_tables.h>
  27 #include <linux/netfilter_ipv6/ip6_tables.h>
  28 #include <linux/netfilter/xt_hashlimit.h>
  29 #include <linux/mutex.h>
  30
  31 MODULE_LICENSE("GPL");
  32 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  33 MODULE_DESCRIPTION("iptables match for limiting per hash-bucket");
  34 MODULE_ALIAS("ipt_hashlimit");
  35 MODULE_ALIAS("ip6t_hashlimit");
  36
  37 /* need to declare this at the top */
  38 static struct proc_dir_entry *hashlimit_procdir4;
  39 static struct proc_dir_entry *hashlimit_procdir6;
  40 static const struct file_operations dl_file_ops;
  41
  42 /* hash table crap */
  43 struct dsthash_dst {
  44         union {
  45                 struct {
  46                         __be32 src;
  47                         __be32 dst;
  48                 } ip;
  49                 struct {
  50                         __be32 src[4];
  51                         __be32 dst[4];
  52                 } ip6;
  53         } addr;
  54         __be16 src_port;
  55         __be16 dst_port;
  56 };
  57
  58 struct dsthash_ent {
  59         /* static / read-only parts in the beginning */
  60         struct hlist_node node;
  61         struct dsthash_dst dst;
  62
  63         /* modified structure members in the end */
  64         unsigned long expires;          /* precalculated expiry time */
  65         struct {
  66                 unsigned long prev;     /* last modification */
  67                 u_int32_t credit;
  68                 u_int32_t credit_cap, cost;
  69         } rateinfo;
  70 };
  71
  72 struct xt_hashlimit_htable {
  73         struct hlist_node node;         /* global list of all htables */
  74         atomic_t use;
  75         int family;
  76
  77         struct hashlimit_cfg cfg;       /* config */
  78
  79         /* used internally */
  80         spinlock_t lock;                /* lock for list_head */
  81         u_int32_t rnd;                  /* random seed for hash */
  82         int rnd_initialized;
  83         unsigned int count;             /* number entries in table */
  84         struct timer_list timer;        /* timer for gc */
  85
  86         /* seq_file stuff */
  87         struct proc_dir_entry *pde;
  88
  89         struct hlist_head hash[0];      /* hashtable itself */
  90 };
  91
  92 static DEFINE_SPINLOCK(hashlimit_lock); /* protects htables list */
  93 static DEFINE_MUTEX(hlimit_mutex);      /* additional checkentry protection */
  94 static HLIST_HEAD(hashlimit_htables);
  95 static struct kmem_cache *hashlimit_cachep __read_mostly;
  96
  97 static inline int dst_cmp(const struct dsthash_ent *ent, struct dsthash_dst *b)
  98 {
  99         return !memcmp(&ent->dst, b, sizeof(ent->dst));
 100 }
 101
 102 static u_int32_t
 103 hash_dst(const struct xt_hashlimit_htable *ht, const struct dsthash_dst *dst)
 104 {
 105         return jhash(dst, sizeof(*dst), ht->rnd) % ht->cfg.size;
 106 }
 107
 108 static struct dsthash_ent *
 109 dsthash_find(const struct xt_hashlimit_htable *ht, struct dsthash_dst *dst)
 110 {
 111         struct dsthash_ent *ent;
 112         struct hlist_node *pos;
 113         u_int32_t hash = hash_dst(ht, dst);
 114
 115         if (!hlist_empty(&ht->hash[hash])) {
 116                 hlist_for_each_entry(ent, pos, &ht->hash[hash], node)
 117                         if (dst_cmp(ent, dst))
 118                                 return ent;
 119         }
 120         return NULL;
 121 }
 122
 123 /* allocate dsthash_ent, initialize dst, put in htable and lock it */
 124 static struct dsthash_ent *
 125 dsthash_alloc_init(struct xt_hashlimit_htable *ht, struct dsthash_dst *dst)
 126 {
 127         struct dsthash_ent *ent;
 128
 129         /* initialize hash with random val at the time we allocate
 130          * the first hashtable entry */
 131         if (!ht->rnd_initialized) {
 132                 get_random_bytes(&ht->rnd, 4);
 133                 ht->rnd_initialized = 1;
 134         }
 135
 136         if (ht->cfg.max && ht->count >= ht->cfg.max) {
 137                 /* FIXME: do something. question is what.. */
 138                 if (net_ratelimit())
 139                         printk(KERN_WARNING
 140                                 "xt_hashlimit: max count of %u reached\n",
 141                                 ht->cfg.max);
 142                 return NULL;
 143         }
 144
 145         ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
 146         if (!ent) {
 147                 if (net_ratelimit())
 148                         printk(KERN_ERR
 149                                 "xt_hashlimit: can't allocate dsthash_ent\n");
 150                 return NULL;
 151         }
 152         memcpy(&ent->dst, dst, sizeof(ent->dst));
 153
 154         hlist_add_head(&ent->node, &ht->hash[hash_dst(ht, dst)]);
 155         ht->count++;
 156         return ent;
 157 }
 158
 159 static inline void
 160 dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent)
 161 {
 162         hlist_del(&ent->node);
 163         kmem_cache_free(hashlimit_cachep, ent);
 164         ht->count--;
 165 }
 166 static void htable_gc(unsigned long htlong);
 167
 168 static int htable_create(struct xt_hashlimit_info *minfo, int family)
 169 {
 170         struct xt_hashlimit_htable *hinfo;
 171         unsigned int size;
 172         unsigned int i;
 173
 174         if (minfo->cfg.size)
 175                 size = minfo->cfg.size;
 176         else {
 177                 size = ((num_physpages << PAGE_SHIFT) / 16384) /
 178                        sizeof(struct list_head);
 179                 if (num_physpages > (1024 * 1024 * 1024 / PAGE_SIZE))
 180                         size = 8192;
 181                 if (size < 16)
 182                         size = 16;
 183         }
 184         /* FIXME: don't use vmalloc() here or anywhere else -HW */
 185         hinfo = vmalloc(sizeof(struct xt_hashlimit_htable) +
 186                         sizeof(struct list_head) * size);
 187         if (!hinfo) {
 188                 printk(KERN_ERR "xt_hashlimit: unable to create hashtable\n");
 189                 return -1;
 190         }
 191         minfo->hinfo = hinfo;
 192
 193         /* copy match config into hashtable config */
 194         memcpy(&hinfo->cfg, &minfo->cfg, sizeof(hinfo->cfg));
 195         hinfo->cfg.size = size;
 196         if (!hinfo->cfg.max)
 197                 hinfo->cfg.max = 8 * hinfo->cfg.size;
 198         else if (hinfo->cfg.max < hinfo->cfg.size)
 199                 hinfo->cfg.max = hinfo->cfg.size;
 200
 201         for (i = 0; i < hinfo->cfg.size; i++)
 202                 INIT_HLIST_HEAD(&hinfo->hash[i]);
 203
 204         atomic_set(&hinfo->use, 1);
 205         hinfo->count = 0;
 206         hinfo->family = family;
 207         hinfo->rnd_initialized = 0;
 208         spin_lock_init(&hinfo->lock);
 209         hinfo->pde = create_proc_entry(minfo->name, 0,
 210                                        family == AF_INET ? hashlimit_procdir4 :
 211                                                            hashlimit_procdir6);
 212         if (!hinfo->pde) {
 213                 vfree(hinfo);
 214                 return -1;
 215         }
 216         hinfo->pde->proc_fops = &dl_file_ops;
 217         hinfo->pde->data = hinfo;
 218
 219         init_timer(&hinfo->timer);
 220         hinfo->timer.expires = jiffies + msecs_to_jiffies(hinfo->cfg.gc_interval);
 221         hinfo->timer.data = (unsigned long )hinfo;
 222         hinfo->timer.function = htable_gc;
 223         add_timer(&hinfo->timer);
 224
 225         spin_lock_bh(&hashlimit_lock);
 226         hlist_add_head(&hinfo->node, &hashlimit_htables);
 227         spin_unlock_bh(&hashlimit_lock);
 228
 229         return 0;
 230 }
 231
 232 static int select_all(struct xt_hashlimit_htable *ht, struct dsthash_ent *he)
 233 {
 234         return 1;
 235 }
 236
 237 static int select_gc(struct xt_hashlimit_htable *ht, struct dsthash_ent *he)
 238 {
 239         return (jiffies >= he->expires);
 240 }
 241
 242 static void htable_selective_cleanup(struct xt_hashlimit_htable *ht,
 243                                 int (*select)(struct xt_hashlimit_htable *ht,
 244                                               struct dsthash_ent *he))
 245 {
 246         unsigned int i;
 247
 248         /* lock hash table and iterate over it */
 249         spin_lock_bh(&ht->lock);
 250         for (i = 0; i < ht->cfg.size; i++) {
 251                 struct dsthash_ent *dh;
 252                 struct hlist_node *pos, *n;
 253                 hlist_for_each_entry_safe(dh, pos, n, &ht->hash[i], node) {
 254                         if ((*select)(ht, dh))
 255                                 dsthash_free(ht, dh);
 256                 }
 257         }
 258         spin_unlock_bh(&ht->lock);
 259 }
 260
 261 /* hash table garbage collector, run by timer */
 262 static void htable_gc(unsigned long htlong)
 263 {
 264         struct xt_hashlimit_htable *ht = (struct xt_hashlimit_htable *)htlong;
 265
 266         htable_selective_cleanup(ht, select_gc);
 267
 268         /* re-add the timer accordingly */
 269         ht->timer.expires = jiffies + msecs_to_jiffies(ht->cfg.gc_interval);
 270         add_timer(&ht->timer);
 271 }
 272
 273 static void htable_destroy(struct xt_hashlimit_htable *hinfo)
 274 {
 275         /* remove timer, if it is pending */
 276         if (timer_pending(&hinfo->timer))
 277                 del_timer(&hinfo->timer);
 278
 279         /* remove proc entry */
 280         remove_proc_entry(hinfo->pde->name,
 281                           hinfo->family == AF_INET ? hashlimit_procdir4 :
 282                                                      hashlimit_procdir6);
 283         htable_selective_cleanup(hinfo, select_all);
 284         vfree(hinfo);
 285 }
 286
 287 static struct xt_hashlimit_htable *htable_find_get(char *name, int family)
 288 {
 289         struct xt_hashlimit_htable *hinfo;
 290         struct hlist_node *pos;
 291
 292         spin_lock_bh(&hashlimit_lock);
 293         hlist_for_each_entry(hinfo, pos, &hashlimit_htables, node) {
 294                 if (!strcmp(name, hinfo->pde->name) &&
 295                     hinfo->family == family) {
 296                         atomic_inc(&hinfo->use);
 297                         spin_unlock_bh(&hashlimit_lock);
 298                         return hinfo;
 299                 }
 300         }
 301         spin_unlock_bh(&hashlimit_lock);
 302         return NULL;
 303 }
 304
 305 static void htable_put(struct xt_hashlimit_htable *hinfo)
 306 {
 307         if (atomic_dec_and_test(&hinfo->use)) {
 308                 spin_lock_bh(&hashlimit_lock);
 309                 hlist_del(&hinfo->node);
 310                 spin_unlock_bh(&hashlimit_lock);
 311                 htable_destroy(hinfo);
 312         }
 313 }
 314
 315 /* The algorithm used is the Simple Token Bucket Filter (TBF)
 316  * see net/sched/sch_tbf.c in the linux source tree
 317  */
 318
 319 /* Rusty: This is my (non-mathematically-inclined) understanding of
 320    this algorithm.  The `average rate' in jiffies becomes your initial
 321    amount of credit `credit' and the most credit you can ever have
 322    `credit_cap'.  The `peak rate' becomes the cost of passing the
 323    test, `cost'.
 324
 325    `prev' tracks the last packet hit: you gain one credit per jiffy.
 326    If you get credit balance more than this, the extra credit is
 327    discarded.  Every time the match passes, you lose `cost' credits;
 328    if you don't have that many, the test fails.
 329
 330    See Alexey's formal explanation in net/sched/sch_tbf.c.
 331
 332    To get the maximum range, we multiply by this factor (ie. you get N
 333    credits per jiffy).  We want to allow a rate as low as 1 per day
 334    (slowest userspace tool allows), which means
 335    CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
 336 */
 337 #define MAX_CPJ (0xFFFFFFFF / (HZ*60*60*24))
 338
 339 /* Repeated shift and or gives us all 1s, final shift and add 1 gives
 340  * us the power of 2 below the theoretical max, so GCC simply does a
 341  * shift. */
 342 #define _POW2_BELOW2(x) ((x)|((x)>>1))
 343 #define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
 344 #define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
 345 #define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
 346 #define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
 347 #define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
 348
 349 #define CREDITS_PER_JIFFY POW2_BELOW32(MAX_CPJ)
 350
 351 /* Precision saver. */
 352 static inline u_int32_t
 353 user2credits(u_int32_t user)
 354 {
 355         /* If multiplying would overflow... */
 356         if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY))
 357                 /* Divide first. */
 358                 return (user / XT_HASHLIMIT_SCALE) * HZ * CREDITS_PER_JIFFY;
 359
 360         return (user * HZ * CREDITS_PER_JIFFY) / XT_HASHLIMIT_SCALE;
 361 }
 362
 363 static inline void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now)
 364 {
 365         dh->rateinfo.credit += (now - dh->rateinfo.prev) * CREDITS_PER_JIFFY;
 366         if (dh->rateinfo.credit > dh->rateinfo.credit_cap)
 367                 dh->rateinfo.credit = dh->rateinfo.credit_cap;
 368         dh->rateinfo.prev = now;
 369 }
 370
 371 static int
 372 hashlimit_init_dst(struct xt_hashlimit_htable *hinfo, struct dsthash_dst *dst,
 373                    const struct sk_buff *skb, unsigned int protoff)
 374 {
 375         __be16 _ports[2], *ports;
 376         int nexthdr;
 377
 378         memset(dst, 0, sizeof(*dst));
 379
 380         switch (hinfo->family) {
 381         case AF_INET:
 382                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
 383                         dst->addr.ip.dst = skb->nh.iph->daddr;
 384                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
 385                         dst->addr.ip.src = skb->nh.iph->saddr;
 386
 387                 if (!(hinfo->cfg.mode &
 388                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
 389                         return 0;
 390                 nexthdr = skb->nh.iph->protocol;
 391                 break;
 392 #if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
 393         case AF_INET6:
 394                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
 395                         memcpy(&dst->addr.ip6.dst, &skb->nh.ipv6h->daddr,
 396                                sizeof(dst->addr.ip6.dst));
 397                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
 398                         memcpy(&dst->addr.ip6.src, &skb->nh.ipv6h->saddr,
 399                                sizeof(dst->addr.ip6.src));
 400
 401                 if (!(hinfo->cfg.mode &
 402                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
 403                         return 0;
 404                 nexthdr = ipv6_find_hdr(skb, &protoff, -1, NULL);
 405                 if (nexthdr < 0)
 406                         return -1;
 407                 break;
 408 #endif
 409         default:
 410                 BUG();
 411                 return 0;
 412         }
 413
 414         switch (nexthdr) {
 415         case IPPROTO_TCP:
 416         case IPPROTO_UDP:
 417         case IPPROTO_UDPLITE:
 418         case IPPROTO_SCTP:
 419         case IPPROTO_DCCP:
 420                 ports = skb_header_pointer(skb, protoff, sizeof(_ports),
 421                                            &_ports);
 422                 break;
 423         default:
 424                 _ports[0] = _ports[1] = 0;
 425                 ports = _ports;
 426                 break;
 427         }
 428         if (!ports)
 429                 return -1;
 430         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT)
 431                 dst->src_port = ports[0];
 432         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT)
 433                 dst->dst_port = ports[1];
 434         return 0;
 435 }
 436
 437 static int
 438 hashlimit_match(const struct sk_buff *skb,
 439                 const struct net_device *in,
 440                 const struct net_device *out,
 441                 const struct xt_match *match,
 442                 const void *matchinfo,
 443                 int offset,
 444                 unsigned int protoff,
 445                 int *hotdrop)
 446 {
 447         struct xt_hashlimit_info *r =
 448                 ((struct xt_hashlimit_info *)matchinfo)->u.master;
 449         struct xt_hashlimit_htable *hinfo = r->hinfo;
 450         unsigned long now = jiffies;
 451         struct dsthash_ent *dh;
 452         struct dsthash_dst dst;
 453
 454         if (hashlimit_init_dst(hinfo, &dst, skb, protoff) < 0)
 455                 goto hotdrop;
 456
 457         spin_lock_bh(&hinfo->lock);
 458         dh = dsthash_find(hinfo, &dst);
 459         if (!dh) {
 460                 dh = dsthash_alloc_init(hinfo, &dst);
 461                 if (!dh) {
 462                         spin_unlock_bh(&hinfo->lock);
 463                         goto hotdrop;
 464                 }
 465
 466                 dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
 467                 dh->rateinfo.prev = jiffies;
 468                 dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
 469                                                    hinfo->cfg.burst);
 470                 dh->rateinfo.credit_cap = user2credits(hinfo->cfg.avg *
 471                                                        hinfo->cfg.burst);
 472                 dh->rateinfo.cost = user2credits(hinfo->cfg.avg);
 473         } else {
 474                 /* update expiration timeout */
 475                 dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
 476                 rateinfo_recalc(dh, now);
 477         }
 478
 479         if (dh->rateinfo.credit >= dh->rateinfo.cost) {
 480                 /* We're underlimit. */
 481                 dh->rateinfo.credit -= dh->rateinfo.cost;
 482                 spin_unlock_bh(&hinfo->lock);
 483                 return 1;
 484         }
 485
 486         spin_unlock_bh(&hinfo->lock);
 487
 488         /* default case: we're overlimit, thus don't match */
 489         return 0;
 490
 491 hotdrop:
 492         *hotdrop = 1;
 493         return 0;
 494 }
 495
 496 static int
 497 hashlimit_checkentry(const char *tablename,
 498                      const void *inf,
 499                      const struct xt_match *match,
 500                      void *matchinfo,
 501                      unsigned int hook_mask)
 502 {
 503         struct xt_hashlimit_info *r = matchinfo;
 504
 505         /* Check for overflow. */
 506         if (r->cfg.burst == 0 ||
 507             user2credits(r->cfg.avg * r->cfg.burst) < user2credits(r->cfg.avg)) {
 508                 printk(KERN_ERR "xt_hashlimit: overflow, try lower: %u/%u\n",
 509                        r->cfg.avg, r->cfg.burst);
 510                 return 0;
 511         }
 512         if (r->cfg.mode == 0 ||
 513             r->cfg.mode > (XT_HASHLIMIT_HASH_DPT |
 514                            XT_HASHLIMIT_HASH_DIP |
 515                            XT_HASHLIMIT_HASH_SIP |
 516                            XT_HASHLIMIT_HASH_SPT))
 517                 return 0;
 518         if (!r->cfg.gc_interval)
 519                 return 0;
 520         if (!r->cfg.expire)
 521                 return 0;
 522         if (r->name[sizeof(r->name) - 1] != '\0')
 523                 return 0;
 524
 525         /* This is the best we've got: We cannot release and re-grab lock,
 526          * since checkentry() is called before x_tables.c grabs xt_mutex.
 527          * We also cannot grab the hashtable spinlock, since htable_create will
 528          * call vmalloc, and that can sleep.  And we cannot just re-search
 529          * the list of htable's in htable_create(), since then we would
 530          * create duplicate proc files. -HW */
 531         mutex_lock(&hlimit_mutex);
 532         r->hinfo = htable_find_get(r->name, match->family);
 533         if (!r->hinfo && htable_create(r, match->family) != 0) {
 534                 mutex_unlock(&hlimit_mutex);
 535                 return 0;
 536         }
 537         mutex_unlock(&hlimit_mutex);
 538
 539         /* Ugly hack: For SMP, we only want to use one set */
 540         r->u.master = r;
 541         return 1;
 542 }
 543
 544 static void
 545 hashlimit_destroy(const struct xt_match *match, void *matchinfo)
 546 {
 547         struct xt_hashlimit_info *r = matchinfo;
 548
 549         htable_put(r->hinfo);
 550 }
 551
 552 #ifdef CONFIG_COMPAT
 553 struct compat_xt_hashlimit_info {
 554         char name[IFNAMSIZ];
 555         struct hashlimit_cfg cfg;
 556         compat_uptr_t hinfo;
 557         compat_uptr_t master;
 558 };
 559
 560 static void compat_from_user(void *dst, void *src)
 561 {
 562         int off = offsetof(struct compat_xt_hashlimit_info, hinfo);
 563
 564         memcpy(dst, src, off);
 565         memset(dst + off, 0, sizeof(struct compat_xt_hashlimit_info) - off);
 566 }
 567
 568 static int compat_to_user(void __user *dst, void *src)
 569 {
 570         int off = offsetof(struct compat_xt_hashlimit_info, hinfo);
 571
 572         return copy_to_user(dst, src, off) ? -EFAULT : 0;
 573 }
 574 #endif
 575
 576 static struct xt_match xt_hashlimit[] = {
 577         {
 578                 .name           = "hashlimit",
 579                 .family         = AF_INET,
 580                 .match          = hashlimit_match,
 581                 .matchsize      = sizeof(struct xt_hashlimit_info),
 582 #ifdef CONFIG_COMPAT
 583                 .compatsize     = sizeof(struct compat_xt_hashlimit_info),
 584                 .compat_from_user = compat_from_user,
 585                 .compat_to_user = compat_to_user,
 586 #endif
 587                 .checkentry     = hashlimit_checkentry,
 588                 .destroy        = hashlimit_destroy,
 589                 .me             = THIS_MODULE
 590         },
 591         {
 592                 .name           = "hashlimit",
 593                 .family         = AF_INET6,
 594                 .match          = hashlimit_match,
 595                 .matchsize      = sizeof(struct xt_hashlimit_info),
 596 #ifdef CONFIG_COMPAT
 597                 .compatsize     = sizeof(struct compat_xt_hashlimit_info),
 598                 .compat_from_user = compat_from_user,
 599                 .compat_to_user = compat_to_user,
 600 #endif
 601                 .checkentry     = hashlimit_checkentry,
 602                 .destroy        = hashlimit_destroy,
 603                 .me             = THIS_MODULE
 604         },
 605 };
 606
 607 /* PROC stuff */
 608 static void *dl_seq_start(struct seq_file *s, loff_t *pos)
 609 {
 610         struct proc_dir_entry *pde = s->private;
 611         struct xt_hashlimit_htable *htable = pde->data;
 612         unsigned int *bucket;
 613
 614         spin_lock_bh(&htable->lock);
 615         if (*pos >= htable->cfg.size)
 616                 return NULL;
 617
 618         bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
 619         if (!bucket)
 620                 return ERR_PTR(-ENOMEM);
 621
 622         *bucket = *pos;
 623         return bucket;
 624 }
 625
 626 static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
 627 {
 628         struct proc_dir_entry *pde = s->private;
 629         struct xt_hashlimit_htable *htable = pde->data;
 630         unsigned int *bucket = (unsigned int *)v;
 631
 632         *pos = ++(*bucket);
 633         if (*pos >= htable->cfg.size) {
 634                 kfree(v);
 635                 return NULL;
 636         }
 637         return bucket;
 638 }
 639
 640 static void dl_seq_stop(struct seq_file *s, void *v)
 641 {
 642         struct proc_dir_entry *pde = s->private;
 643         struct xt_hashlimit_htable *htable = pde->data;
 644         unsigned int *bucket = (unsigned int *)v;
 645
 646         kfree(bucket);
 647         spin_unlock_bh(&htable->lock);
 648 }
 649
 650 static int dl_seq_real_show(struct dsthash_ent *ent, int family,
 651                                    struct seq_file *s)
 652 {
 653         /* recalculate to show accurate numbers */
 654         rateinfo_recalc(ent, jiffies);
 655
 656         switch (family) {
 657         case AF_INET:
 658                 return seq_printf(s, "%ld %u.%u.%u.%u:%u->"
 659                                      "%u.%u.%u.%u:%u %u %u %u\n",
 660                                  (long)(ent->expires - jiffies)/HZ,
 661                                  NIPQUAD(ent->dst.addr.ip.src),
 662                                  ntohs(ent->dst.src_port),
 663                                  NIPQUAD(ent->dst.addr.ip.dst),
 664                                  ntohs(ent->dst.dst_port),
 665                                  ent->rateinfo.credit, ent->rateinfo.credit_cap,
 666                                  ent->rateinfo.cost);
 667         case AF_INET6:
 668                 return seq_printf(s, "%ld " NIP6_FMT ":%u->"
 669                                      NIP6_FMT ":%u %u %u %u\n",
 670                                  (long)(ent->expires - jiffies)/HZ,
 671                                  NIP6(*(struct in6_addr *)&ent->dst.addr.ip6.src),
 672                                  ntohs(ent->dst.src_port),
 673                                  NIP6(*(struct in6_addr *)&ent->dst.addr.ip6.dst),
 674                                  ntohs(ent->dst.dst_port),
 675                                  ent->rateinfo.credit, ent->rateinfo.credit_cap,
 676                                  ent->rateinfo.cost);
 677         default:
 678                 BUG();
 679                 return 0;
 680         }
 681 }
 682
 683 static int dl_seq_show(struct seq_file *s, void *v)
 684 {
 685         struct proc_dir_entry *pde = s->private;
 686         struct xt_hashlimit_htable *htable = pde->data;
 687         unsigned int *bucket = (unsigned int *)v;
 688         struct dsthash_ent *ent;
 689         struct hlist_node *pos;
 690
 691         if (!hlist_empty(&htable->hash[*bucket])) {
 692                 hlist_for_each_entry(ent, pos, &htable->hash[*bucket], node)
 693                         if (dl_seq_real_show(ent, htable->family, s))
 694                                 return 1;
 695         }
 696         return 0;
 697 }
 698
 699 static struct seq_operations dl_seq_ops = {
 700         .start = dl_seq_start,
 701         .next  = dl_seq_next,
 702         .stop  = dl_seq_stop,
 703         .show  = dl_seq_show
 704 };
 705
 706 static int dl_proc_open(struct inode *inode, struct file *file)
 707 {
 708         int ret = seq_open(file, &dl_seq_ops);
 709
 710         if (!ret) {
 711                 struct seq_file *sf = file->private_data;
 712                 sf->private = PDE(inode);
 713         }
 714         return ret;
 715 }
 716
 717 static const struct file_operations dl_file_ops = {
 718         .owner   = THIS_MODULE,
 719         .open    = dl_proc_open,
 720         .read    = seq_read,
 721         .llseek  = seq_lseek,
 722         .release = seq_release
 723 };
 724
 725 static int __init xt_hashlimit_init(void)
 726 {
 727         int err;
 728
 729         err = xt_register_matches(xt_hashlimit, ARRAY_SIZE(xt_hashlimit));
 730         if (err < 0)
 731                 goto err1;
 732
 733         err = -ENOMEM;
 734         hashlimit_cachep = kmem_cache_create("xt_hashlimit",
 735                                             sizeof(struct dsthash_ent), 0, 0,
 736                                             NULL, NULL);
 737         if (!hashlimit_cachep) {
 738                 printk(KERN_ERR "xt_hashlimit: unable to create slab cache\n");
 739                 goto err2;
 740         }
 741         hashlimit_procdir4 = proc_mkdir("ipt_hashlimit", proc_net);
 742         if (!hashlimit_procdir4) {
 743                 printk(KERN_ERR "xt_hashlimit: unable to create proc dir "
 744                                 "entry\n");
 745                 goto err3;
 746         }
 747         hashlimit_procdir6 = proc_mkdir("ip6t_hashlimit", proc_net);
 748         if (!hashlimit_procdir6) {
 749                 printk(KERN_ERR "xt_hashlimit: unable to create proc dir "
 750                                 "entry\n");
 751                 goto err4;
 752         }
 753         return 0;
 754 err4:
 755         remove_proc_entry("ipt_hashlimit", proc_net);
 756 err3:
 757         kmem_cache_destroy(hashlimit_cachep);
 758 err2:
 759         xt_unregister_matches(xt_hashlimit, ARRAY_SIZE(xt_hashlimit));
 760 err1:
 761         return err;
 762
 763 }
 764
 765 static void __exit xt_hashlimit_fini(void)
 766 {
 767         remove_proc_entry("ipt_hashlimit", proc_net);
 768         remove_proc_entry("ip6t_hashlimit", proc_net);
 769         kmem_cache_destroy(hashlimit_cachep);
 770         xt_unregister_matches(xt_hashlimit, ARRAY_SIZE(xt_hashlimit));
 771 }
 772
 773 module_init(xt_hashlimit_init);
 774 module_exit(xt_hashlimit_fini);