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