SAFE public projects git trees. - safe/jmp/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 #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_mt(const struct sk_buff *skb, const struct net_device *in,
 445              const struct net_device *out, const struct xt_match *match,
 446              const void *matchinfo, int offset, unsigned int protoff,
 447              bool *hotdrop)
 448 {
 449         const struct xt_hashlimit_info *r =
 450                 ((const struct xt_hashlimit_info *)matchinfo)->u.master;
 451         struct xt_hashlimit_htable *hinfo = r->hinfo;
 452         unsigned long now = jiffies;
 453         struct dsthash_ent *dh;
 454         struct dsthash_dst dst;
 455
 456         if (hashlimit_init_dst(hinfo, &dst, skb, protoff) < 0)
 457                 goto hotdrop;
 458
 459         spin_lock_bh(&hinfo->lock);
 460         dh = dsthash_find(hinfo, &dst);
 461         if (!dh) {
 462                 dh = dsthash_alloc_init(hinfo, &dst);
 463                 if (!dh) {
 464                         spin_unlock_bh(&hinfo->lock);
 465                         goto hotdrop;
 466                 }
 467
 468                 dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
 469                 dh->rateinfo.prev = jiffies;
 470                 dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
 471                                                    hinfo->cfg.burst);
 472                 dh->rateinfo.credit_cap = user2credits(hinfo->cfg.avg *
 473                                                        hinfo->cfg.burst);
 474                 dh->rateinfo.cost = user2credits(hinfo->cfg.avg);
 475         } else {
 476                 /* update expiration timeout */
 477                 dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
 478                 rateinfo_recalc(dh, now);
 479         }
 480
 481         if (dh->rateinfo.credit >= dh->rateinfo.cost) {
 482                 /* We're underlimit. */
 483                 dh->rateinfo.credit -= dh->rateinfo.cost;
 484                 spin_unlock_bh(&hinfo->lock);
 485                 return true;
 486         }
 487
 488         spin_unlock_bh(&hinfo->lock);
 489
 490         /* default case: we're overlimit, thus don't match */
 491         return false;
 492
 493 hotdrop:
 494         *hotdrop = true;
 495         return false;
 496 }
 497
 498 static bool
 499 hashlimit_mt_check(const char *tablename, const void *inf,
 500                    const struct xt_match *match, 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 false;
 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 false;
 518         if (!r->cfg.gc_interval)
 519                 return false;
 520         if (!r->cfg.expire)
 521                 return false;
 522         if (r->name[sizeof(r->name) - 1] != '\0')
 523                 return false;
 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 false;
 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 true;
 542 }
 543
 544 static void
 545 hashlimit_mt_destroy(const struct xt_match *match, void *matchinfo)
 546 {
 547         const 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 hashlimit_mt_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 hashlimit_mt_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 hashlimit_mt_reg[] __read_mostly = {
 577         {
 578                 .name           = "hashlimit",
 579                 .family         = AF_INET,
 580                 .match          = hashlimit_mt,
 581                 .matchsize      = sizeof(struct xt_hashlimit_info),
 582 #ifdef CONFIG_COMPAT
 583                 .compatsize     = sizeof(struct compat_xt_hashlimit_info),
 584                 .compat_from_user = hashlimit_mt_compat_from_user,
 585                 .compat_to_user = hashlimit_mt_compat_to_user,
 586 #endif
 587                 .checkentry     = hashlimit_mt_check,
 588                 .destroy        = hashlimit_mt_destroy,
 589                 .me             = THIS_MODULE
 590         },
 591         {
 592                 .name           = "hashlimit",
 593                 .family         = AF_INET6,
 594                 .match          = hashlimit_mt,
 595                 .matchsize      = sizeof(struct xt_hashlimit_info),
 596 #ifdef CONFIG_COMPAT
 597                 .compatsize     = sizeof(struct compat_xt_hashlimit_info),
 598                 .compat_from_user = hashlimit_mt_compat_from_user,
 599                 .compat_to_user = hashlimit_mt_compat_to_user,
 600 #endif
 601                 .checkentry     = hashlimit_mt_check,
 602                 .destroy        = hashlimit_mt_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 const 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 hashlimit_mt_init(void)
 726 {
 727         int err;
 728
 729         err = xt_register_matches(hashlimit_mt_reg,
 730               ARRAY_SIZE(hashlimit_mt_reg));
 731         if (err < 0)
 732                 goto err1;
 733
 734         err = -ENOMEM;
 735         hashlimit_cachep = kmem_cache_create("xt_hashlimit",
 736                                             sizeof(struct dsthash_ent), 0, 0,
 737                                             NULL);
 738         if (!hashlimit_cachep) {
 739                 printk(KERN_ERR "xt_hashlimit: unable to create slab cache\n");
 740                 goto err2;
 741         }
 742         hashlimit_procdir4 = proc_mkdir("ipt_hashlimit", init_net.proc_net);
 743         if (!hashlimit_procdir4) {
 744                 printk(KERN_ERR "xt_hashlimit: unable to create proc dir "
 745                                 "entry\n");
 746                 goto err3;
 747         }
 748         hashlimit_procdir6 = proc_mkdir("ip6t_hashlimit", init_net.proc_net);
 749         if (!hashlimit_procdir6) {
 750                 printk(KERN_ERR "xt_hashlimit: unable to create proc dir "
 751                                 "entry\n");
 752                 goto err4;
 753         }
 754         return 0;
 755 err4:
 756         remove_proc_entry("ipt_hashlimit", init_net.proc_net);
 757 err3:
 758         kmem_cache_destroy(hashlimit_cachep);
 759 err2:
 760         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
 761 err1:
 762         return err;
 763
 764 }
 765
 766 static void __exit hashlimit_mt_exit(void)
 767 {
 768         remove_proc_entry("ipt_hashlimit", init_net.proc_net);
 769         remove_proc_entry("ip6t_hashlimit", init_net.proc_net);
 770         kmem_cache_destroy(hashlimit_cachep);
 771         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
 772 }
 773
 774 module_init(hashlimit_mt_init);
 775 module_exit(hashlimit_mt_exit);