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