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 #include <net/ipv6.h>
  25 #include <net/net_namespace.h>
  26
  27 #include <linux/netfilter/x_tables.h>
  28 #include <linux/netfilter_ipv4/ip_tables.h>
  29 #include <linux/netfilter_ipv6/ip6_tables.h>
  30 #include <linux/netfilter/xt_hashlimit.h>
  31 #include <linux/mutex.h>
  32
  33 MODULE_LICENSE("GPL");
  34 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  35 MODULE_DESCRIPTION("iptables match for limiting per hash-bucket");
  36 MODULE_ALIAS("ipt_hashlimit");
  37 MODULE_ALIAS("ip6t_hashlimit");
  38
  39 /* need to declare this at the top */
  40 static struct proc_dir_entry *hashlimit_procdir4;
  41 static struct proc_dir_entry *hashlimit_procdir6;
  42 static const struct file_operations dl_file_ops;
  43
  44 /* hash table crap */
  45 struct dsthash_dst {
  46         union {
  47                 struct {
  48                         __be32 src;
  49                         __be32 dst;
  50                 } ip;
  51                 struct {
  52                         __be32 src[4];
  53                         __be32 dst[4];
  54                 } ip6;
  55         } addr;
  56         __be16 src_port;
  57         __be16 dst_port;
  58 };
  59
  60 struct dsthash_ent {
  61         /* static / read-only parts in the beginning */
  62         struct hlist_node node;
  63         struct dsthash_dst dst;
  64
  65         /* modified structure members in the end */
  66         unsigned long expires;          /* precalculated expiry time */
  67         struct {
  68                 unsigned long prev;     /* last modification */
  69                 u_int32_t credit;
  70                 u_int32_t credit_cap, cost;
  71         } rateinfo;
  72 };
  73
  74 struct xt_hashlimit_htable {
  75         struct hlist_node node;         /* global list of all htables */
  76         atomic_t use;
  77         int family;
  78
  79         struct hashlimit_cfg cfg;       /* config */
  80
  81         /* used internally */
  82         spinlock_t lock;                /* lock for list_head */
  83         u_int32_t rnd;                  /* random seed for hash */
  84         int rnd_initialized;
  85         unsigned int count;             /* number entries in table */
  86         struct timer_list timer;        /* timer for gc */
  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 DEFINE_MUTEX(hlimit_mutex);      /* additional checkentry protection */
  96 static HLIST_HEAD(hashlimit_htables);
  97 static struct kmem_cache *hashlimit_cachep __read_mostly;
  98
  99 static inline bool dst_cmp(const struct dsthash_ent *ent,
 100                            const struct dsthash_dst *b)
 101 {
 102         return !memcmp(&ent->dst, b, sizeof(ent->dst));
 103 }
 104
 105 static u_int32_t
 106 hash_dst(const struct xt_hashlimit_htable *ht, const struct dsthash_dst *dst)
 107 {
 108         return jhash(dst, sizeof(*dst), ht->rnd) % ht->cfg.size;
 109 }
 110
 111 static struct dsthash_ent *
 112 dsthash_find(const struct xt_hashlimit_htable *ht,
 113              const struct dsthash_dst *dst)
 114 {
 115         struct dsthash_ent *ent;
 116         struct hlist_node *pos;
 117         u_int32_t hash = hash_dst(ht, dst);
 118
 119         if (!hlist_empty(&ht->hash[hash])) {
 120                 hlist_for_each_entry(ent, pos, &ht->hash[hash], node)
 121                         if (dst_cmp(ent, dst))
 122                                 return ent;
 123         }
 124         return NULL;
 125 }
 126
 127 /* allocate dsthash_ent, initialize dst, put in htable and lock it */
 128 static struct dsthash_ent *
 129 dsthash_alloc_init(struct xt_hashlimit_htable *ht,
 130                    const struct dsthash_dst *dst)
 131 {
 132         struct dsthash_ent *ent;
 133
 134         /* initialize hash with random val at the time we allocate
 135          * the first hashtable entry */
 136         if (!ht->rnd_initialized) {
 137                 get_random_bytes(&ht->rnd, 4);
 138                 ht->rnd_initialized = 1;
 139         }
 140
 141         if (ht->cfg.max && ht->count >= ht->cfg.max) {
 142                 /* FIXME: do something. question is what.. */
 143                 if (net_ratelimit())
 144                         printk(KERN_WARNING
 145                                 "xt_hashlimit: max count of %u reached\n",
 146                                 ht->cfg.max);
 147                 return NULL;
 148         }
 149
 150         ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
 151         if (!ent) {
 152                 if (net_ratelimit())
 153                         printk(KERN_ERR
 154                                 "xt_hashlimit: can't allocate dsthash_ent\n");
 155                 return NULL;
 156         }
 157         memcpy(&ent->dst, dst, sizeof(ent->dst));
 158
 159         hlist_add_head(&ent->node, &ht->hash[hash_dst(ht, dst)]);
 160         ht->count++;
 161         return ent;
 162 }
 163
 164 static inline void
 165 dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent)
 166 {
 167         hlist_del(&ent->node);
 168         kmem_cache_free(hashlimit_cachep, ent);
 169         ht->count--;
 170 }
 171 static void htable_gc(unsigned long htlong);
 172
 173 static int htable_create(struct xt_hashlimit_info *minfo, int family)
 174 {
 175         struct xt_hashlimit_htable *hinfo;
 176         unsigned int size;
 177         unsigned int i;
 178
 179         if (minfo->cfg.size)
 180                 size = minfo->cfg.size;
 181         else {
 182                 size = ((num_physpages << PAGE_SHIFT) / 16384) /
 183                        sizeof(struct list_head);
 184                 if (num_physpages > (1024 * 1024 * 1024 / PAGE_SIZE))
 185                         size = 8192;
 186                 if (size < 16)
 187                         size = 16;
 188         }
 189         /* FIXME: don't use vmalloc() here or anywhere else -HW */
 190         hinfo = vmalloc(sizeof(struct xt_hashlimit_htable) +
 191                         sizeof(struct list_head) * size);
 192         if (!hinfo) {
 193                 printk(KERN_ERR "xt_hashlimit: unable to create hashtable\n");
 194                 return -1;
 195         }
 196         minfo->hinfo = hinfo;
 197
 198         /* copy match config into hashtable config */
 199         memcpy(&hinfo->cfg, &minfo->cfg, sizeof(hinfo->cfg));
 200         hinfo->cfg.size = size;
 201         if (!hinfo->cfg.max)
 202                 hinfo->cfg.max = 8 * hinfo->cfg.size;
 203         else if (hinfo->cfg.max < hinfo->cfg.size)
 204                 hinfo->cfg.max = hinfo->cfg.size;
 205
 206         for (i = 0; i < hinfo->cfg.size; i++)
 207                 INIT_HLIST_HEAD(&hinfo->hash[i]);
 208
 209         atomic_set(&hinfo->use, 1);
 210         hinfo->count = 0;
 211         hinfo->family = family;
 212         hinfo->rnd_initialized = 0;
 213         spin_lock_init(&hinfo->lock);
 214         hinfo->pde = create_proc_entry(minfo->name, 0,
 215                                        family == AF_INET ? hashlimit_procdir4 :
 216                                                            hashlimit_procdir6);
 217         if (!hinfo->pde) {
 218                 vfree(hinfo);
 219                 return -1;
 220         }
 221         hinfo->pde->proc_fops = &dl_file_ops;
 222         hinfo->pde->data = hinfo;
 223
 224         setup_timer(&hinfo->timer, htable_gc, (unsigned long )hinfo);
 225         hinfo->timer.expires = jiffies + msecs_to_jiffies(hinfo->cfg.gc_interval);
 226         add_timer(&hinfo->timer);
 227
 228         spin_lock_bh(&hashlimit_lock);
 229         hlist_add_head(&hinfo->node, &hashlimit_htables);
 230         spin_unlock_bh(&hashlimit_lock);
 231
 232         return 0;
 233 }
 234
 235 static bool select_all(const struct xt_hashlimit_htable *ht,
 236                        const struct dsthash_ent *he)
 237 {
 238         return 1;
 239 }
 240
 241 static bool select_gc(const struct xt_hashlimit_htable *ht,
 242                       const struct dsthash_ent *he)
 243 {
 244         return time_after_eq(jiffies, he->expires);
 245 }
 246
 247 static void htable_selective_cleanup(struct xt_hashlimit_htable *ht,
 248                         bool (*select)(const struct xt_hashlimit_htable *ht,
 249                                       const struct dsthash_ent *he))
 250 {
 251         unsigned int i;
 252
 253         /* lock hash table and iterate over it */
 254         spin_lock_bh(&ht->lock);
 255         for (i = 0; i < ht->cfg.size; i++) {
 256                 struct dsthash_ent *dh;
 257                 struct hlist_node *pos, *n;
 258                 hlist_for_each_entry_safe(dh, pos, n, &ht->hash[i], node) {
 259                         if ((*select)(ht, dh))
 260                                 dsthash_free(ht, dh);
 261                 }
 262         }
 263         spin_unlock_bh(&ht->lock);
 264 }
 265
 266 /* hash table garbage collector, run by timer */
 267 static void htable_gc(unsigned long htlong)
 268 {
 269         struct xt_hashlimit_htable *ht = (struct xt_hashlimit_htable *)htlong;
 270
 271         htable_selective_cleanup(ht, select_gc);
 272
 273         /* re-add the timer accordingly */
 274         ht->timer.expires = jiffies + msecs_to_jiffies(ht->cfg.gc_interval);
 275         add_timer(&ht->timer);
 276 }
 277
 278 static void htable_destroy(struct xt_hashlimit_htable *hinfo)
 279 {
 280         /* remove timer, if it is pending */
 281         if (timer_pending(&hinfo->timer))
 282                 del_timer(&hinfo->timer);
 283
 284         /* remove proc entry */
 285         remove_proc_entry(hinfo->pde->name,
 286                           hinfo->family == AF_INET ? hashlimit_procdir4 :
 287                                                      hashlimit_procdir6);
 288         htable_selective_cleanup(hinfo, select_all);
 289         vfree(hinfo);
 290 }
 291
 292 static struct xt_hashlimit_htable *htable_find_get(const char *name,
 293                                                    int family)
 294 {
 295         struct xt_hashlimit_htable *hinfo;
 296         struct hlist_node *pos;
 297
 298         spin_lock_bh(&hashlimit_lock);
 299         hlist_for_each_entry(hinfo, pos, &hashlimit_htables, node) {
 300                 if (!strcmp(name, hinfo->pde->name) &&
 301                     hinfo->family == family) {
 302                         atomic_inc(&hinfo->use);
 303                         spin_unlock_bh(&hashlimit_lock);
 304                         return hinfo;
 305                 }
 306         }
 307         spin_unlock_bh(&hashlimit_lock);
 308         return NULL;
 309 }
 310
 311 static void htable_put(struct xt_hashlimit_htable *hinfo)
 312 {
 313         if (atomic_dec_and_test(&hinfo->use)) {
 314                 spin_lock_bh(&hashlimit_lock);
 315                 hlist_del(&hinfo->node);
 316                 spin_unlock_bh(&hashlimit_lock);
 317                 htable_destroy(hinfo);
 318         }
 319 }
 320
 321 /* The algorithm used is the Simple Token Bucket Filter (TBF)
 322  * see net/sched/sch_tbf.c in the linux source tree
 323  */
 324
 325 /* Rusty: This is my (non-mathematically-inclined) understanding of
 326    this algorithm.  The `average rate' in jiffies becomes your initial
 327    amount of credit `credit' and the most credit you can ever have
 328    `credit_cap'.  The `peak rate' becomes the cost of passing the
 329    test, `cost'.
 330
 331    `prev' tracks the last packet hit: you gain one credit per jiffy.
 332    If you get credit balance more than this, the extra credit is
 333    discarded.  Every time the match passes, you lose `cost' credits;
 334    if you don't have that many, the test fails.
 335
 336    See Alexey's formal explanation in net/sched/sch_tbf.c.
 337
 338    To get the maximum range, we multiply by this factor (ie. you get N
 339    credits per jiffy).  We want to allow a rate as low as 1 per day
 340    (slowest userspace tool allows), which means
 341    CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
 342 */
 343 #define MAX_CPJ (0xFFFFFFFF / (HZ*60*60*24))
 344
 345 /* Repeated shift and or gives us all 1s, final shift and add 1 gives
 346  * us the power of 2 below the theoretical max, so GCC simply does a
 347  * shift. */
 348 #define _POW2_BELOW2(x) ((x)|((x)>>1))
 349 #define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
 350 #define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
 351 #define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
 352 #define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
 353 #define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
 354
 355 #define CREDITS_PER_JIFFY POW2_BELOW32(MAX_CPJ)
 356
 357 /* Precision saver. */
 358 static inline u_int32_t
 359 user2credits(u_int32_t user)
 360 {
 361         /* If multiplying would overflow... */
 362         if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY))
 363                 /* Divide first. */
 364                 return (user / XT_HASHLIMIT_SCALE) * HZ * CREDITS_PER_JIFFY;
 365
 366         return (user * HZ * CREDITS_PER_JIFFY) / XT_HASHLIMIT_SCALE;
 367 }
 368
 369 static inline void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now)
 370 {
 371         dh->rateinfo.credit += (now - dh->rateinfo.prev) * CREDITS_PER_JIFFY;
 372         if (dh->rateinfo.credit > dh->rateinfo.credit_cap)
 373                 dh->rateinfo.credit = dh->rateinfo.credit_cap;
 374         dh->rateinfo.prev = now;
 375 }
 376
 377 static int
 378 hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
 379                    struct dsthash_dst *dst,
 380                    const struct sk_buff *skb, unsigned int protoff)
 381 {
 382         __be16 _ports[2], *ports;
 383         u8 nexthdr;
 384
 385         memset(dst, 0, sizeof(*dst));
 386
 387         switch (hinfo->family) {
 388         case AF_INET:
 389                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
 390                         dst->addr.ip.dst = ip_hdr(skb)->daddr;
 391                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
 392                         dst->addr.ip.src = ip_hdr(skb)->saddr;
 393
 394                 if (!(hinfo->cfg.mode &
 395                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
 396                         return 0;
 397                 nexthdr = ip_hdr(skb)->protocol;
 398                 break;
 399 #if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
 400         case AF_INET6:
 401                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
 402                         memcpy(&dst->addr.ip6.dst, &ipv6_hdr(skb)->daddr,
 403                                sizeof(dst->addr.ip6.dst));
 404                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
 405                         memcpy(&dst->addr.ip6.src, &ipv6_hdr(skb)->saddr,
 406                                sizeof(dst->addr.ip6.src));
 407
 408                 if (!(hinfo->cfg.mode &
 409                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
 410                         return 0;
 411                 nexthdr = ipv6_hdr(skb)->nexthdr;
 412                 protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr);
 413                 if ((int)protoff < 0)
 414                         return -1;
 415                 break;
 416 #endif
 417         default:
 418                 BUG();
 419                 return 0;
 420         }
 421
 422         switch (nexthdr) {
 423         case IPPROTO_TCP:
 424         case IPPROTO_UDP:
 425         case IPPROTO_UDPLITE:
 426         case IPPROTO_SCTP:
 427         case IPPROTO_DCCP:
 428                 ports = skb_header_pointer(skb, protoff, sizeof(_ports),
 429                                            &_ports);
 430                 break;
 431         default:
 432                 _ports[0] = _ports[1] = 0;
 433                 ports = _ports;
 434                 break;
 435         }
 436         if (!ports)
 437                 return -1;
 438         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT)
 439                 dst->src_port = ports[0];
 440         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT)
 441                 dst->dst_port = ports[1];
 442         return 0;
 443 }
 444
 445 static bool
 446 hashlimit_mt(const struct sk_buff *skb, const struct net_device *in,
 447              const struct net_device *out, const struct xt_match *match,
 448              const void *matchinfo, int offset, unsigned int protoff,
 449              bool *hotdrop)
 450 {
 451         const struct xt_hashlimit_info *r =
 452                 ((const struct xt_hashlimit_info *)matchinfo)->u.master;
 453         struct xt_hashlimit_htable *hinfo = r->hinfo;
 454         unsigned long now = jiffies;
 455         struct dsthash_ent *dh;
 456         struct dsthash_dst dst;
 457
 458         if (hashlimit_init_dst(hinfo, &dst, skb, protoff) < 0)
 459                 goto hotdrop;
 460
 461         spin_lock_bh(&hinfo->lock);
 462         dh = dsthash_find(hinfo, &dst);
 463         if (!dh) {
 464                 dh = dsthash_alloc_init(hinfo, &dst);
 465                 if (!dh) {
 466                         spin_unlock_bh(&hinfo->lock);
 467                         goto hotdrop;
 468                 }
 469
 470                 dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
 471                 dh->rateinfo.prev = jiffies;
 472                 dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
 473                                                    hinfo->cfg.burst);
 474                 dh->rateinfo.credit_cap = user2credits(hinfo->cfg.avg *
 475                                                        hinfo->cfg.burst);
 476                 dh->rateinfo.cost = user2credits(hinfo->cfg.avg);
 477         } else {
 478                 /* update expiration timeout */
 479                 dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
 480                 rateinfo_recalc(dh, now);
 481         }
 482
 483         if (dh->rateinfo.credit >= dh->rateinfo.cost) {
 484                 /* We're underlimit. */
 485                 dh->rateinfo.credit -= dh->rateinfo.cost;
 486                 spin_unlock_bh(&hinfo->lock);
 487                 return true;
 488         }
 489
 490         spin_unlock_bh(&hinfo->lock);
 491
 492         /* default case: we're overlimit, thus don't match */
 493         return false;
 494
 495 hotdrop:
 496         *hotdrop = true;
 497         return false;
 498 }
 499
 500 static bool
 501 hashlimit_mt_check(const char *tablename, const void *inf,
 502                    const struct xt_match *match, void *matchinfo,
 503                    unsigned int hook_mask)
 504 {
 505         struct xt_hashlimit_info *r = matchinfo;
 506
 507         /* Check for overflow. */
 508         if (r->cfg.burst == 0 ||
 509             user2credits(r->cfg.avg * r->cfg.burst) < user2credits(r->cfg.avg)) {
 510                 printk(KERN_ERR "xt_hashlimit: overflow, try lower: %u/%u\n",
 511                        r->cfg.avg, r->cfg.burst);
 512                 return false;
 513         }
 514         if (r->cfg.mode == 0 ||
 515             r->cfg.mode > (XT_HASHLIMIT_HASH_DPT |
 516                            XT_HASHLIMIT_HASH_DIP |
 517                            XT_HASHLIMIT_HASH_SIP |
 518                            XT_HASHLIMIT_HASH_SPT))
 519                 return false;
 520         if (!r->cfg.gc_interval)
 521                 return false;
 522         if (!r->cfg.expire)
 523                 return false;
 524         if (r->name[sizeof(r->name) - 1] != '\0')
 525                 return false;
 526
 527         /* This is the best we've got: We cannot release and re-grab lock,
 528          * since checkentry() is called before x_tables.c grabs xt_mutex.
 529          * We also cannot grab the hashtable spinlock, since htable_create will
 530          * call vmalloc, and that can sleep.  And we cannot just re-search
 531          * the list of htable's in htable_create(), since then we would
 532          * create duplicate proc files. -HW */
 533         mutex_lock(&hlimit_mutex);
 534         r->hinfo = htable_find_get(r->name, match->family);
 535         if (!r->hinfo && htable_create(r, match->family) != 0) {
 536                 mutex_unlock(&hlimit_mutex);
 537                 return false;
 538         }
 539         mutex_unlock(&hlimit_mutex);
 540
 541         /* Ugly hack: For SMP, we only want to use one set */
 542         r->u.master = r;
 543         return true;
 544 }
 545
 546 static void
 547 hashlimit_mt_destroy(const struct xt_match *match, void *matchinfo)
 548 {
 549         const struct xt_hashlimit_info *r = matchinfo;
 550
 551         htable_put(r->hinfo);
 552 }
 553
 554 #ifdef CONFIG_COMPAT
 555 struct compat_xt_hashlimit_info {
 556         char name[IFNAMSIZ];
 557         struct hashlimit_cfg cfg;
 558         compat_uptr_t hinfo;
 559         compat_uptr_t master;
 560 };
 561
 562 static void hashlimit_mt_compat_from_user(void *dst, void *src)
 563 {
 564         int off = offsetof(struct compat_xt_hashlimit_info, hinfo);
 565
 566         memcpy(dst, src, off);
 567         memset(dst + off, 0, sizeof(struct compat_xt_hashlimit_info) - off);
 568 }
 569
 570 static int hashlimit_mt_compat_to_user(void __user *dst, void *src)
 571 {
 572         int off = offsetof(struct compat_xt_hashlimit_info, hinfo);
 573
 574         return copy_to_user(dst, src, off) ? -EFAULT : 0;
 575 }
 576 #endif
 577
 578 static struct xt_match hashlimit_mt_reg[] __read_mostly = {
 579         {
 580                 .name           = "hashlimit",
 581                 .family         = AF_INET,
 582                 .match          = hashlimit_mt,
 583                 .matchsize      = sizeof(struct xt_hashlimit_info),
 584 #ifdef CONFIG_COMPAT
 585                 .compatsize     = sizeof(struct compat_xt_hashlimit_info),
 586                 .compat_from_user = hashlimit_mt_compat_from_user,
 587                 .compat_to_user = hashlimit_mt_compat_to_user,
 588 #endif
 589                 .checkentry     = hashlimit_mt_check,
 590                 .destroy        = hashlimit_mt_destroy,
 591                 .me             = THIS_MODULE
 592         },
 593         {
 594                 .name           = "hashlimit",
 595                 .family         = AF_INET6,
 596                 .match          = hashlimit_mt,
 597                 .matchsize      = sizeof(struct xt_hashlimit_info),
 598 #ifdef CONFIG_COMPAT
 599                 .compatsize     = sizeof(struct compat_xt_hashlimit_info),
 600                 .compat_from_user = hashlimit_mt_compat_from_user,
 601                 .compat_to_user = hashlimit_mt_compat_to_user,
 602 #endif
 603                 .checkentry     = hashlimit_mt_check,
 604                 .destroy        = hashlimit_mt_destroy,
 605                 .me             = THIS_MODULE
 606         },
 607 };
 608
 609 /* PROC stuff */
 610 static void *dl_seq_start(struct seq_file *s, loff_t *pos)
 611 {
 612         struct proc_dir_entry *pde = s->private;
 613         struct xt_hashlimit_htable *htable = pde->data;
 614         unsigned int *bucket;
 615
 616         spin_lock_bh(&htable->lock);
 617         if (*pos >= htable->cfg.size)
 618                 return NULL;
 619
 620         bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
 621         if (!bucket)
 622                 return ERR_PTR(-ENOMEM);
 623
 624         *bucket = *pos;
 625         return bucket;
 626 }
 627
 628 static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
 629 {
 630         struct proc_dir_entry *pde = s->private;
 631         struct xt_hashlimit_htable *htable = pde->data;
 632         unsigned int *bucket = (unsigned int *)v;
 633
 634         *pos = ++(*bucket);
 635         if (*pos >= htable->cfg.size) {
 636                 kfree(v);
 637                 return NULL;
 638         }
 639         return bucket;
 640 }
 641
 642 static void dl_seq_stop(struct seq_file *s, void *v)
 643 {
 644         struct proc_dir_entry *pde = s->private;
 645         struct xt_hashlimit_htable *htable = pde->data;
 646         unsigned int *bucket = (unsigned int *)v;
 647
 648         kfree(bucket);
 649         spin_unlock_bh(&htable->lock);
 650 }
 651
 652 static int dl_seq_real_show(struct dsthash_ent *ent, int family,
 653                                    struct seq_file *s)
 654 {
 655         /* recalculate to show accurate numbers */
 656         rateinfo_recalc(ent, jiffies);
 657
 658         switch (family) {
 659         case AF_INET:
 660                 return seq_printf(s, "%ld %u.%u.%u.%u:%u->"
 661                                      "%u.%u.%u.%u:%u %u %u %u\n",
 662                                  (long)(ent->expires - jiffies)/HZ,
 663                                  NIPQUAD(ent->dst.addr.ip.src),
 664                                  ntohs(ent->dst.src_port),
 665                                  NIPQUAD(ent->dst.addr.ip.dst),
 666                                  ntohs(ent->dst.dst_port),
 667                                  ent->rateinfo.credit, ent->rateinfo.credit_cap,
 668                                  ent->rateinfo.cost);
 669         case AF_INET6:
 670                 return seq_printf(s, "%ld " NIP6_FMT ":%u->"
 671                                      NIP6_FMT ":%u %u %u %u\n",
 672                                  (long)(ent->expires - jiffies)/HZ,
 673                                  NIP6(*(struct in6_addr *)&ent->dst.addr.ip6.src),
 674                                  ntohs(ent->dst.src_port),
 675                                  NIP6(*(struct in6_addr *)&ent->dst.addr.ip6.dst),
 676                                  ntohs(ent->dst.dst_port),
 677                                  ent->rateinfo.credit, ent->rateinfo.credit_cap,
 678                                  ent->rateinfo.cost);
 679         default:
 680                 BUG();
 681                 return 0;
 682         }
 683 }
 684
 685 static int dl_seq_show(struct seq_file *s, void *v)
 686 {
 687         struct proc_dir_entry *pde = s->private;
 688         struct xt_hashlimit_htable *htable = pde->data;
 689         unsigned int *bucket = (unsigned int *)v;
 690         struct dsthash_ent *ent;
 691         struct hlist_node *pos;
 692
 693         if (!hlist_empty(&htable->hash[*bucket])) {
 694                 hlist_for_each_entry(ent, pos, &htable->hash[*bucket], node)
 695                         if (dl_seq_real_show(ent, htable->family, s))
 696                                 return 1;
 697         }
 698         return 0;
 699 }
 700
 701 static const struct seq_operations dl_seq_ops = {
 702         .start = dl_seq_start,
 703         .next  = dl_seq_next,
 704         .stop  = dl_seq_stop,
 705         .show  = dl_seq_show
 706 };
 707
 708 static int dl_proc_open(struct inode *inode, struct file *file)
 709 {
 710         int ret = seq_open(file, &dl_seq_ops);
 711
 712         if (!ret) {
 713                 struct seq_file *sf = file->private_data;
 714                 sf->private = PDE(inode);
 715         }
 716         return ret;
 717 }
 718
 719 static const struct file_operations dl_file_ops = {
 720         .owner   = THIS_MODULE,
 721         .open    = dl_proc_open,
 722         .read    = seq_read,
 723         .llseek  = seq_lseek,
 724         .release = seq_release
 725 };
 726
 727 static int __init hashlimit_mt_init(void)
 728 {
 729         int err;
 730
 731         err = xt_register_matches(hashlimit_mt_reg,
 732               ARRAY_SIZE(hashlimit_mt_reg));
 733         if (err < 0)
 734                 goto err1;
 735
 736         err = -ENOMEM;
 737         hashlimit_cachep = kmem_cache_create("xt_hashlimit",
 738                                             sizeof(struct dsthash_ent), 0, 0,
 739                                             NULL);
 740         if (!hashlimit_cachep) {
 741                 printk(KERN_ERR "xt_hashlimit: unable to create slab cache\n");
 742                 goto err2;
 743         }
 744         hashlimit_procdir4 = proc_mkdir("ipt_hashlimit", init_net.proc_net);
 745         if (!hashlimit_procdir4) {
 746                 printk(KERN_ERR "xt_hashlimit: unable to create proc dir "
 747                                 "entry\n");
 748                 goto err3;
 749         }
 750         hashlimit_procdir6 = proc_mkdir("ip6t_hashlimit", init_net.proc_net);
 751         if (!hashlimit_procdir6) {
 752                 printk(KERN_ERR "xt_hashlimit: unable to create proc dir "
 753                                 "entry\n");
 754                 goto err4;
 755         }
 756         return 0;
 757 err4:
 758         remove_proc_entry("ipt_hashlimit", init_net.proc_net);
 759 err3:
 760         kmem_cache_destroy(hashlimit_cachep);
 761 err2:
 762         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
 763 err1:
 764         return err;
 765
 766 }
 767
 768 static void __exit hashlimit_mt_exit(void)
 769 {
 770         remove_proc_entry("ipt_hashlimit", init_net.proc_net);
 771         remove_proc_entry("ip6t_hashlimit", init_net.proc_net);
 772         kmem_cache_destroy(hashlimit_cachep);
 773         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
 774 }
 775
 776 module_init(hashlimit_mt_init);
 777 module_exit(hashlimit_mt_exit);