net/ipv4/netfilter/ipt_hashlimit.c

   1 /* iptables match extension to limit the number of packets per second
   2  * seperately for each hashbucket (sourceip/sourceport/dstip/dstport)
   3  *
   4  * (C) 2003-2004 by Harald Welte <laforge@netfilter.org>
   5  *
   6  * $Id: ipt_hashlimit.c 3244 2004-10-20 16:24:29Z laforge@netfilter.org $
   7  *
   8  * Development of this code was funded by Astaro AG, http://www.astaro.com/
   9  *
  10  * based on ipt_limit.c by:
  11  * Jérôme de Vivie    <devivie@info.enserb.u-bordeaux.fr>
  12  * Hervé Eychenne      <eychenne@info.enserb.u-bordeaux.fr>
  13  * Rusty Russell        <rusty@rustcorp.com.au>
  14  *
  15  * The general idea is to create a hash table for every dstip and have a
  16  * seperate limit counter per tuple.  This way you can do something like 'limit
  17  * the number of syn packets for each of my internal addresses.
  18  *
  19  * Ideally this would just be implemented as a general 'hash' match, which would
  20  * allow us to attach any iptables target to it's hash buckets.  But this is
  21  * not possible in the current iptables architecture.  As always, pkttables for
  22  * 2.7.x will help ;)
  23  */
  24 #include <linux/module.h>
  25 #include <linux/skbuff.h>
  26 #include <linux/spinlock.h>
  27 #include <linux/random.h>
  28 #include <linux/jhash.h>
  29 #include <linux/slab.h>
  30 #include <linux/vmalloc.h>
  31 #include <linux/tcp.h>
  32 #include <linux/udp.h>
  33 #include <linux/sctp.h>
  34 #include <linux/proc_fs.h>
  35 #include <linux/seq_file.h>
  36 #include <linux/list.h>
  37
  38 #include <linux/netfilter_ipv4/ip_tables.h>
  39 #include <linux/netfilter_ipv4/ipt_hashlimit.h>
  40
  41 /* FIXME: this is just for IP_NF_ASSERRT */
  42 #include <linux/netfilter_ipv4/ip_conntrack.h>
  43
  44 MODULE_LICENSE("GPL");
  45 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  46 MODULE_DESCRIPTION("iptables match for limiting per hash-bucket");
  47
  48 /* need to declare this at the top */
  49 static struct proc_dir_entry *hashlimit_procdir;
  50 static struct file_operations dl_file_ops;
  51
  52 /* hash table crap */
  53
  54 struct dsthash_dst {
  55         u_int32_t src_ip;
  56         u_int32_t dst_ip;
  57         /* ports have to be consecutive !!! */
  58         u_int16_t src_port;
  59         u_int16_t dst_port;
  60 };
  61
  62 struct dsthash_ent {
  63         /* static / read-only parts in the beginning */
  64         struct hlist_node node;
  65         struct dsthash_dst dst;
  66
  67         /* modified structure members in the end */
  68         unsigned long expires;          /* precalculated expiry time */
  69         struct {
  70                 unsigned long prev;     /* last modification */
  71                 u_int32_t credit;
  72                 u_int32_t credit_cap, cost;
  73         } rateinfo;
  74 };
  75
  76 struct ipt_hashlimit_htable {
  77         struct hlist_node node;         /* global list of all htables */
  78         atomic_t use;
  79
  80         struct hashlimit_cfg cfg;       /* config */
  81
  82         /* used internally */
  83         spinlock_t lock;                /* lock for list_head */
  84         u_int32_t rnd;                  /* random seed for hash */
  85         struct timer_list timer;        /* timer for gc */
  86         atomic_t count;                 /* number entries in table */
  87
  88         /* seq_file stuff */
  89         struct proc_dir_entry *pde;
  90
  91         struct hlist_head hash[0];      /* hashtable itself */
  92 };
  93
  94 static DEFINE_SPINLOCK(hashlimit_lock); /* protects htables list */
  95 static DECLARE_MUTEX(hlimit_mutex);     /* additional checkentry protection */
  96 static HLIST_HEAD(hashlimit_htables);
  97 static kmem_cache_t *hashlimit_cachep;
  98
  99 static inline int dst_cmp(const struct dsthash_ent *ent, struct dsthash_dst *b)
 100 {
 101         return (ent->dst.dst_ip == b->dst_ip
 102                 && ent->dst.dst_port == b->dst_port
 103                 && ent->dst.src_port == b->src_port
 104                 && ent->dst.src_ip == b->src_ip);
 105 }
 106
 107 static inline u_int32_t
 108 hash_dst(const struct ipt_hashlimit_htable *ht, const struct dsthash_dst *dst)
 109 {
 110         return (jhash_3words(dst->dst_ip, (dst->dst_port<<16 | dst->src_port),
 111                              dst->src_ip, ht->rnd) % ht->cfg.size);
 112 }
 113
 114 static inline struct dsthash_ent *
 115 __dsthash_find(const struct ipt_hashlimit_htable *ht, struct dsthash_dst *dst)
 116 {
 117         struct dsthash_ent *ent;
 118         struct hlist_node *pos;
 119         u_int32_t hash = hash_dst(ht, dst);
 120
 121         if (!hlist_empty(&ht->hash[hash]))
 122                 hlist_for_each_entry(ent, pos, &ht->hash[hash], node) {
 123                         if (dst_cmp(ent, dst)) {
 124                                 return ent;
 125                         }
 126                 }
 127
 128         return NULL;
 129 }
 130
 131 /* allocate dsthash_ent, initialize dst, put in htable and lock it */
 132 static struct dsthash_ent *
 133 __dsthash_alloc_init(struct ipt_hashlimit_htable *ht, struct dsthash_dst *dst)
 134 {
 135         struct dsthash_ent *ent;
 136
 137         /* initialize hash with random val at the time we allocate
 138          * the first hashtable entry */
 139         if (!ht->rnd)
 140                 get_random_bytes(&ht->rnd, 4);
 141
 142         if (ht->cfg.max &&
 143             atomic_read(&ht->count) >= ht->cfg.max) {
 144                 /* FIXME: do something. question is what.. */
 145                 if (net_ratelimit())
 146                         printk(KERN_WARNING
 147                                 "ipt_hashlimit: max count of %u reached\n",
 148                                 ht->cfg.max);
 149                 return NULL;
 150         }
 151
 152         ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
 153         if (!ent) {
 154                 if (net_ratelimit())
 155                         printk(KERN_ERR
 156                                 "ipt_hashlimit: can't allocate dsthash_ent\n");
 157                 return NULL;
 158         }
 159
 160         atomic_inc(&ht->count);
 161
 162         ent->dst.dst_ip = dst->dst_ip;
 163         ent->dst.dst_port = dst->dst_port;
 164         ent->dst.src_ip = dst->src_ip;
 165         ent->dst.src_port = dst->src_port;
 166
 167         hlist_add_head(&ent->node, &ht->hash[hash_dst(ht, dst)]);
 168
 169         return ent;
 170 }
 171
 172 static inline void
 173 __dsthash_free(struct ipt_hashlimit_htable *ht, struct dsthash_ent *ent)
 174 {
 175         hlist_del(&ent->node);
 176         kmem_cache_free(hashlimit_cachep, ent);
 177         atomic_dec(&ht->count);
 178 }
 179 static void htable_gc(unsigned long htlong);
 180
 181 static int htable_create(struct ipt_hashlimit_info *minfo)
 182 {
 183         int i;
 184         unsigned int size;
 185         struct ipt_hashlimit_htable *hinfo;
 186
 187         if (minfo->cfg.size)
 188                 size = minfo->cfg.size;
 189         else {
 190                 size = (((num_physpages << PAGE_SHIFT) / 16384)
 191                          / sizeof(struct list_head));
 192                 if (num_physpages > (1024 * 1024 * 1024 / PAGE_SIZE))
 193                         size = 8192;
 194                 if (size < 16)
 195                         size = 16;
 196         }
 197         /* FIXME: don't use vmalloc() here or anywhere else -HW */
 198         hinfo = vmalloc(sizeof(struct ipt_hashlimit_htable)
 199                         + (sizeof(struct list_head) * size));
 200         if (!hinfo) {
 201                 printk(KERN_ERR "ipt_hashlimit: Unable to create hashtable\n");
 202                 return -1;
 203         }
 204         minfo->hinfo = hinfo;
 205
 206         /* copy match config into hashtable config */
 207         memcpy(&hinfo->cfg, &minfo->cfg, sizeof(hinfo->cfg));
 208         hinfo->cfg.size = size;
 209         if (!hinfo->cfg.max)
 210                 hinfo->cfg.max = 8 * hinfo->cfg.size;
 211         else if (hinfo->cfg.max < hinfo->cfg.size)
 212                 hinfo->cfg.max = hinfo->cfg.size;
 213
 214         for (i = 0; i < hinfo->cfg.size; i++)
 215                 INIT_HLIST_HEAD(&hinfo->hash[i]);
 216
 217         atomic_set(&hinfo->count, 0);
 218         atomic_set(&hinfo->use, 1);
 219         hinfo->rnd = 0;
 220         spin_lock_init(&hinfo->lock);
 221         hinfo->pde = create_proc_entry(minfo->name, 0, hashlimit_procdir);
 222         if (!hinfo->pde) {
 223                 vfree(hinfo);
 224                 return -1;
 225         }
 226         hinfo->pde->proc_fops = &dl_file_ops;
 227         hinfo->pde->data = hinfo;
 228
 229         init_timer(&hinfo->timer);
 230         hinfo->timer.expires = jiffies + msecs_to_jiffies(hinfo->cfg.gc_interval);
 231         hinfo->timer.data = (unsigned long )hinfo;
 232         hinfo->timer.function = htable_gc;
 233         add_timer(&hinfo->timer);
 234
 235         spin_lock_bh(&hashlimit_lock);
 236         hlist_add_head(&hinfo->node, &hashlimit_htables);
 237         spin_unlock_bh(&hashlimit_lock);
 238
 239         return 0;
 240 }
 241
 242 static int select_all(struct ipt_hashlimit_htable *ht, struct dsthash_ent *he)
 243 {
 244         return 1;
 245 }
 246
 247 static int select_gc(struct ipt_hashlimit_htable *ht, struct dsthash_ent *he)
 248 {
 249         return (jiffies >= he->expires);
 250 }
 251
 252 static void htable_selective_cleanup(struct ipt_hashlimit_htable *ht,
 253                                 int (*select)(struct ipt_hashlimit_htable *ht,
 254                                               struct dsthash_ent *he))
 255 {
 256         int i;
 257
 258         IP_NF_ASSERT(ht->cfg.size && ht->cfg.max);
 259
 260         /* lock hash table and iterate over it */
 261         spin_lock_bh(&ht->lock);
 262         for (i = 0; i < ht->cfg.size; i++) {
 263                 struct dsthash_ent *dh;
 264                 struct hlist_node *pos, *n;
 265                 hlist_for_each_entry_safe(dh, pos, n, &ht->hash[i], node) {
 266                         if ((*select)(ht, dh))
 267                                 __dsthash_free(ht, dh);
 268                 }
 269         }
 270         spin_unlock_bh(&ht->lock);
 271 }
 272
 273 /* hash table garbage collector, run by timer */
 274 static void htable_gc(unsigned long htlong)
 275 {
 276         struct ipt_hashlimit_htable *ht = (struct ipt_hashlimit_htable *)htlong;
 277
 278         htable_selective_cleanup(ht, select_gc);
 279
 280         /* re-add the timer accordingly */
 281         ht->timer.expires = jiffies + msecs_to_jiffies(ht->cfg.gc_interval);
 282         add_timer(&ht->timer);
 283 }
 284
 285 static void htable_destroy(struct ipt_hashlimit_htable *hinfo)
 286 {
 287         /* remove timer, if it is pending */
 288         if (timer_pending(&hinfo->timer))
 289                 del_timer(&hinfo->timer);
 290
 291         /* remove proc entry */
 292         remove_proc_entry(hinfo->pde->name, hashlimit_procdir);
 293
 294         htable_selective_cleanup(hinfo, select_all);
 295         vfree(hinfo);
 296 }
 297
 298 static struct ipt_hashlimit_htable *htable_find_get(char *name)
 299 {
 300         struct ipt_hashlimit_htable *hinfo;
 301         struct hlist_node *pos;
 302
 303         spin_lock_bh(&hashlimit_lock);
 304         hlist_for_each_entry(hinfo, pos, &hashlimit_htables, node) {
 305                 if (!strcmp(name, hinfo->pde->name)) {
 306                         atomic_inc(&hinfo->use);
 307                         spin_unlock_bh(&hashlimit_lock);
 308                         return hinfo;
 309                 }
 310         }
 311         spin_unlock_bh(&hashlimit_lock);
 312
 313         return NULL;
 314 }
 315
 316 static void htable_put(struct ipt_hashlimit_htable *hinfo)
 317 {
 318         if (atomic_dec_and_test(&hinfo->use)) {
 319                 spin_lock_bh(&hashlimit_lock);
 320                 hlist_del(&hinfo->node);
 321                 spin_unlock_bh(&hashlimit_lock);
 322                 htable_destroy(hinfo);
 323         }
 324 }
 325
 326
 327 /* The algorithm used is the Simple Token Bucket Filter (TBF)
 328  * see net/sched/sch_tbf.c in the linux source tree
 329  */
 330
 331 /* Rusty: This is my (non-mathematically-inclined) understanding of
 332    this algorithm.  The `average rate' in jiffies becomes your initial
 333    amount of credit `credit' and the most credit you can ever have
 334    `credit_cap'.  The `peak rate' becomes the cost of passing the
 335    test, `cost'.
 336
 337    `prev' tracks the last packet hit: you gain one credit per jiffy.
 338    If you get credit balance more than this, the extra credit is
 339    discarded.  Every time the match passes, you lose `cost' credits;
 340    if you don't have that many, the test fails.
 341
 342    See Alexey's formal explanation in net/sched/sch_tbf.c.
 343
 344    To get the maximum range, we multiply by this factor (ie. you get N
 345    credits per jiffy).  We want to allow a rate as low as 1 per day
 346    (slowest userspace tool allows), which means
 347    CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
 348 */
 349 #define MAX_CPJ (0xFFFFFFFF / (HZ*60*60*24))
 350
 351 /* Repeated shift and or gives us all 1s, final shift and add 1 gives
 352  * us the power of 2 below the theoretical max, so GCC simply does a
 353  * shift. */
 354 #define _POW2_BELOW2(x) ((x)|((x)>>1))
 355 #define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
 356 #define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
 357 #define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
 358 #define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
 359 #define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
 360
 361 #define CREDITS_PER_JIFFY POW2_BELOW32(MAX_CPJ)
 362
 363 /* Precision saver. */
 364 static inline u_int32_t
 365 user2credits(u_int32_t user)
 366 {
 367         /* If multiplying would overflow... */
 368         if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY))
 369                 /* Divide first. */
 370                 return (user / IPT_HASHLIMIT_SCALE) * HZ * CREDITS_PER_JIFFY;
 371
 372         return (user * HZ * CREDITS_PER_JIFFY) / IPT_HASHLIMIT_SCALE;
 373 }
 374
 375 static inline void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now)
 376 {
 377         dh->rateinfo.credit += (now - xchg(&dh->rateinfo.prev, now))
 378                                         * CREDITS_PER_JIFFY;
 379         if (dh->rateinfo.credit > dh->rateinfo.credit_cap)
 380                 dh->rateinfo.credit = dh->rateinfo.credit_cap;
 381 }
 382
 383 static inline int get_ports(const struct sk_buff *skb, int offset,
 384                             u16 ports[2])
 385 {
 386         union {
 387                 struct tcphdr th;
 388                 struct udphdr uh;
 389                 sctp_sctphdr_t sctph;
 390         } hdr_u, *ptr_u;
 391
 392         /* Must not be a fragment. */
 393         if (offset)
 394                 return 1;
 395
 396         /* Must be big enough to read ports (both UDP and TCP have
 397            them at the start). */
 398         ptr_u = skb_header_pointer(skb, skb->nh.iph->ihl*4, 8, &hdr_u);
 399         if (!ptr_u)
 400                 return 1;
 401
 402         switch (skb->nh.iph->protocol) {
 403                 case IPPROTO_TCP:
 404                         ports[0] = ptr_u->th.source;
 405                         ports[1] = ptr_u->th.dest;
 406                         break;
 407                 case IPPROTO_UDP:
 408                         ports[0] = ptr_u->uh.source;
 409                         ports[1] = ptr_u->uh.dest;
 410                         break;
 411                 case IPPROTO_SCTP:
 412                         ports[0] = ptr_u->sctph.source;
 413                         ports[1] = ptr_u->sctph.dest;
 414                         break;
 415                 default:
 416                         /* all other protocols don't supprot per-port hash
 417                          * buckets */
 418                         ports[0] = ports[1] = 0;
 419                         break;
 420         }
 421
 422         return 0;
 423 }
 424
 425
 426 static int
 427 hashlimit_match(const struct sk_buff *skb,
 428                 const struct net_device *in,
 429                 const struct net_device *out,
 430                 const void *matchinfo,
 431                 int offset,
 432                 int *hotdrop)
 433 {
 434         struct ipt_hashlimit_info *r =
 435                 ((struct ipt_hashlimit_info *)matchinfo)->u.master;
 436         struct ipt_hashlimit_htable *hinfo = r->hinfo;
 437         unsigned long now = jiffies;
 438         struct dsthash_ent *dh;
 439         struct dsthash_dst dst;
 440
 441         /* build 'dst' according to hinfo->cfg and current packet */
 442         memset(&dst, 0, sizeof(dst));
 443         if (hinfo->cfg.mode & IPT_HASHLIMIT_HASH_DIP)
 444                 dst.dst_ip = skb->nh.iph->daddr;
 445         if (hinfo->cfg.mode & IPT_HASHLIMIT_HASH_SIP)
 446                 dst.src_ip = skb->nh.iph->saddr;
 447         if (hinfo->cfg.mode & IPT_HASHLIMIT_HASH_DPT
 448             ||hinfo->cfg.mode & IPT_HASHLIMIT_HASH_SPT) {
 449                 u_int16_t ports[2];
 450                 if (get_ports(skb, offset, ports)) {
 451                         /* We've been asked to examine this packet, and we
 452                           can't.  Hence, no choice but to drop. */
 453                         *hotdrop = 1;
 454                         return 0;
 455                 }
 456                 if (hinfo->cfg.mode & IPT_HASHLIMIT_HASH_SPT)
 457                         dst.src_port = ports[0];
 458                 if (hinfo->cfg.mode & IPT_HASHLIMIT_HASH_DPT)
 459                         dst.dst_port = ports[1];
 460         }
 461
 462         spin_lock_bh(&hinfo->lock);
 463         dh = __dsthash_find(hinfo, &dst);
 464         if (!dh) {
 465                 dh = __dsthash_alloc_init(hinfo, &dst);
 466
 467                 if (!dh) {
 468                         /* enomem... don't match == DROP */
 469                         if (net_ratelimit())
 470                                 printk(KERN_ERR "%s: ENOMEM\n", __FUNCTION__);
 471                         spin_unlock_bh(&hinfo->lock);
 472                         return 0;
 473                 }
 474
 475                 dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
 476
 477                 dh->rateinfo.prev = jiffies;
 478                 dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
 479                                                         hinfo->cfg.burst);
 480                 dh->rateinfo.credit_cap = user2credits(hinfo->cfg.avg *
 481                                                         hinfo->cfg.burst);
 482                 dh->rateinfo.cost = user2credits(hinfo->cfg.avg);
 483
 484                 spin_unlock_bh(&hinfo->lock);
 485                 return 1;
 486         }
 487
 488         /* update expiration timeout */
 489         dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
 490
 491         rateinfo_recalc(dh, now);
 492         if (dh->rateinfo.credit >= dh->rateinfo.cost) {
 493                 /* We're underlimit. */
 494                 dh->rateinfo.credit -= dh->rateinfo.cost;
 495                 spin_unlock_bh(&hinfo->lock);
 496                 return 1;
 497         }
 498
 499         spin_unlock_bh(&hinfo->lock);
 500
 501         /* default case: we're overlimit, thus don't match */
 502         return 0;
 503 }
 504
 505 static int
 506 hashlimit_checkentry(const char *tablename,
 507                      const struct ipt_ip *ip,
 508                      void *matchinfo,
 509                      unsigned int matchsize,
 510                      unsigned int hook_mask)
 511 {
 512         struct ipt_hashlimit_info *r = matchinfo;
 513
 514         if (matchsize != IPT_ALIGN(sizeof(struct ipt_hashlimit_info)))
 515                 return 0;
 516
 517         /* Check for overflow. */
 518         if (r->cfg.burst == 0
 519             || user2credits(r->cfg.avg * r->cfg.burst) <
 520                                         user2credits(r->cfg.avg)) {
 521                 printk(KERN_ERR "ipt_hashlimit: Overflow, try lower: %u/%u\n",
 522                        r->cfg.avg, r->cfg.burst);
 523                 return 0;
 524         }
 525
 526         if (r->cfg.mode == 0
 527             || r->cfg.mode > (IPT_HASHLIMIT_HASH_DPT
 528                           |IPT_HASHLIMIT_HASH_DIP
 529                           |IPT_HASHLIMIT_HASH_SIP
 530                           |IPT_HASHLIMIT_HASH_SPT))
 531                 return 0;
 532
 533         if (!r->cfg.gc_interval)
 534                 return 0;
 535
 536         if (!r->cfg.expire)
 537                 return 0;
 538
 539         /* This is the best we've got: We cannot release and re-grab lock,
 540          * since checkentry() is called before ip_tables.c grabs ipt_mutex.
 541          * We also cannot grab the hashtable spinlock, since htable_create will
 542          * call vmalloc, and that can sleep.  And we cannot just re-search
 543          * the list of htable's in htable_create(), since then we would
 544          * create duplicate proc files. -HW */
 545         down(&hlimit_mutex);
 546         r->hinfo = htable_find_get(r->name);
 547         if (!r->hinfo && (htable_create(r) != 0)) {
 548                 up(&hlimit_mutex);
 549                 return 0;
 550         }
 551         up(&hlimit_mutex);
 552
 553         /* Ugly hack: For SMP, we only want to use one set */
 554         r->u.master = r;
 555
 556         return 1;
 557 }
 558
 559 static void
 560 hashlimit_destroy(void *matchinfo, unsigned int matchsize)
 561 {
 562         struct ipt_hashlimit_info *r = (struct ipt_hashlimit_info *) matchinfo;
 563
 564         htable_put(r->hinfo);
 565 }
 566
 567 static struct ipt_match ipt_hashlimit = {
 568         .name = "hashlimit",
 569         .match = hashlimit_match,
 570         .checkentry = hashlimit_checkentry,
 571         .destroy = hashlimit_destroy,
 572         .me = THIS_MODULE
 573 };
 574
 575 /* PROC stuff */
 576
 577 static void *dl_seq_start(struct seq_file *s, loff_t *pos)
 578 {
 579         struct proc_dir_entry *pde = s->private;
 580         struct ipt_hashlimit_htable *htable = pde->data;
 581         unsigned int *bucket;
 582
 583         spin_lock_bh(&htable->lock);
 584         if (*pos >= htable->cfg.size)
 585                 return NULL;
 586
 587         bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
 588         if (!bucket)
 589                 return ERR_PTR(-ENOMEM);
 590
 591         *bucket = *pos;
 592         return bucket;
 593 }
 594
 595 static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
 596 {
 597         struct proc_dir_entry *pde = s->private;
 598         struct ipt_hashlimit_htable *htable = pde->data;
 599         unsigned int *bucket = (unsigned int *)v;
 600
 601         *pos = ++(*bucket);
 602         if (*pos >= htable->cfg.size) {
 603                 kfree(v);
 604                 return NULL;
 605         }
 606         return bucket;
 607 }
 608
 609 static void dl_seq_stop(struct seq_file *s, void *v)
 610 {
 611         struct proc_dir_entry *pde = s->private;
 612         struct ipt_hashlimit_htable *htable = pde->data;
 613         unsigned int *bucket = (unsigned int *)v;
 614
 615         kfree(bucket);
 616
 617         spin_unlock_bh(&htable->lock);
 618 }
 619
 620 static inline int dl_seq_real_show(struct dsthash_ent *ent, struct seq_file *s)
 621 {
 622         /* recalculate to show accurate numbers */
 623         rateinfo_recalc(ent, jiffies);
 624
 625         return seq_printf(s, "%ld %u.%u.%u.%u:%u->%u.%u.%u.%u:%u %u %u %u\n",
 626                         (long)(ent->expires - jiffies)/HZ,
 627                         NIPQUAD(ent->dst.src_ip), ntohs(ent->dst.src_port),
 628                         NIPQUAD(ent->dst.dst_ip), ntohs(ent->dst.dst_port),
 629                         ent->rateinfo.credit, ent->rateinfo.credit_cap,
 630                         ent->rateinfo.cost);
 631 }
 632
 633 static int dl_seq_show(struct seq_file *s, void *v)
 634 {
 635         struct proc_dir_entry *pde = s->private;
 636         struct ipt_hashlimit_htable *htable = pde->data;
 637         unsigned int *bucket = (unsigned int *)v;
 638         struct dsthash_ent *ent;
 639         struct hlist_node *pos;
 640
 641         if (!hlist_empty(&htable->hash[*bucket]))
 642                 hlist_for_each_entry(ent, pos, &htable->hash[*bucket], node) {
 643                         if (dl_seq_real_show(ent, s)) {
 644                                 /* buffer was filled and unable to print that tuple */
 645                                 return 1;
 646                         }
 647                 }
 648
 649         return 0;
 650 }
 651
 652 static struct seq_operations dl_seq_ops = {
 653         .start = dl_seq_start,
 654         .next  = dl_seq_next,
 655         .stop  = dl_seq_stop,
 656         .show  = dl_seq_show
 657 };
 658
 659 static int dl_proc_open(struct inode *inode, struct file *file)
 660 {
 661         int ret = seq_open(file, &dl_seq_ops);
 662
 663         if (!ret) {
 664                 struct seq_file *sf = file->private_data;
 665                 sf->private = PDE(inode);
 666         }
 667         return ret;
 668 }
 669
 670 static struct file_operations dl_file_ops = {
 671         .owner   = THIS_MODULE,
 672         .open    = dl_proc_open,
 673         .read    = seq_read,
 674         .llseek  = seq_lseek,
 675         .release = seq_release
 676 };
 677
 678 static int init_or_fini(int fini)
 679 {
 680         int ret = 0;
 681
 682         if (fini)
 683                 goto cleanup;
 684
 685         if (ipt_register_match(&ipt_hashlimit)) {
 686                 ret = -EINVAL;
 687                 goto cleanup_nothing;
 688         }
 689
 690         hashlimit_cachep = kmem_cache_create("ipt_hashlimit",
 691                                             sizeof(struct dsthash_ent), 0,
 692                                             0, NULL, NULL);
 693         if (!hashlimit_cachep) {
 694                 printk(KERN_ERR "Unable to create ipt_hashlimit slab cache\n");
 695                 ret = -ENOMEM;
 696                 goto cleanup_unreg_match;
 697         }
 698
 699         hashlimit_procdir = proc_mkdir("ipt_hashlimit", proc_net);
 700         if (!hashlimit_procdir) {
 701                 printk(KERN_ERR "Unable to create proc dir entry\n");
 702                 ret = -ENOMEM;
 703                 goto cleanup_free_slab;
 704         }
 705
 706         return ret;
 707
 708 cleanup:
 709         remove_proc_entry("ipt_hashlimit", proc_net);
 710 cleanup_free_slab:
 711         kmem_cache_destroy(hashlimit_cachep);
 712 cleanup_unreg_match:
 713         ipt_unregister_match(&ipt_hashlimit);
 714 cleanup_nothing:
 715         return ret;
 716
 717 }
 718
 719 static int __init init(void)
 720 {
 721         return init_or_fini(0);
 722 }
 723
 724 static void __exit fini(void)
 725 {
 726         init_or_fini(1);
 727 }
 728
 729 module_init(init);
 730 module_exit(fini);