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         u_int32_t hash = jhash2((const u32 *)dst,
 109                                 sizeof(*dst)/sizeof(u32),
 110                                 ht->rnd);
 111         /*
 112          * Instead of returning hash % ht->cfg.size (implying a divide)
 113          * we return the high 32 bits of the (hash * ht->cfg.size) that will
 114          * give results between [0 and cfg.size-1] and same hash distribution,
 115          * but using a multiply, less expensive than a divide
 116          */
 117         return ((u64)hash * ht->cfg.size) >> 32;
 118 }
 119
 120 static struct dsthash_ent *
 121 dsthash_find(const struct xt_hashlimit_htable *ht,
 122              const struct dsthash_dst *dst)
 123 {
 124         struct dsthash_ent *ent;
 125         struct hlist_node *pos;
 126         u_int32_t hash = hash_dst(ht, dst);
 127
 128         if (!hlist_empty(&ht->hash[hash])) {
 129                 hlist_for_each_entry(ent, pos, &ht->hash[hash], node)
 130                         if (dst_cmp(ent, dst))
 131                                 return ent;
 132         }
 133         return NULL;
 134 }
 135
 136 /* allocate dsthash_ent, initialize dst, put in htable and lock it */
 137 static struct dsthash_ent *
 138 dsthash_alloc_init(struct xt_hashlimit_htable *ht,
 139                    const struct dsthash_dst *dst)
 140 {
 141         struct dsthash_ent *ent;
 142
 143         /* initialize hash with random val at the time we allocate
 144          * the first hashtable entry */
 145         if (!ht->rnd_initialized) {
 146                 get_random_bytes(&ht->rnd, 4);
 147                 ht->rnd_initialized = 1;
 148         }
 149
 150         if (ht->cfg.max && ht->count >= ht->cfg.max) {
 151                 /* FIXME: do something. question is what.. */
 152                 if (net_ratelimit())
 153                         printk(KERN_WARNING
 154                                 "xt_hashlimit: max count of %u reached\n",
 155                                 ht->cfg.max);
 156                 return NULL;
 157         }
 158
 159         ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
 160         if (!ent) {
 161                 if (net_ratelimit())
 162                         printk(KERN_ERR
 163                                 "xt_hashlimit: can't allocate dsthash_ent\n");
 164                 return NULL;
 165         }
 166         memcpy(&ent->dst, dst, sizeof(ent->dst));
 167
 168         hlist_add_head(&ent->node, &ht->hash[hash_dst(ht, dst)]);
 169         ht->count++;
 170         return ent;
 171 }
 172
 173 static inline void
 174 dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent)
 175 {
 176         hlist_del(&ent->node);
 177         kmem_cache_free(hashlimit_cachep, ent);
 178         ht->count--;
 179 }
 180 static void htable_gc(unsigned long htlong);
 181
 182 static int htable_create(struct xt_hashlimit_info *minfo, int family)
 183 {
 184         struct xt_hashlimit_htable *hinfo;
 185         unsigned int size;
 186         unsigned int i;
 187
 188         if (minfo->cfg.size)
 189                 size = minfo->cfg.size;
 190         else {
 191                 size = ((num_physpages << PAGE_SHIFT) / 16384) /
 192                        sizeof(struct list_head);
 193                 if (num_physpages > (1024 * 1024 * 1024 / PAGE_SIZE))
 194                         size = 8192;
 195                 if (size < 16)
 196                         size = 16;
 197         }
 198         /* FIXME: don't use vmalloc() here or anywhere else -HW */
 199         hinfo = vmalloc(sizeof(struct xt_hashlimit_htable) +
 200                         sizeof(struct list_head) * size);
 201         if (!hinfo) {
 202                 printk(KERN_ERR "xt_hashlimit: unable to create hashtable\n");
 203                 return -1;
 204         }
 205         minfo->hinfo = hinfo;
 206
 207         /* copy match config into hashtable config */
 208         memcpy(&hinfo->cfg, &minfo->cfg, sizeof(hinfo->cfg));
 209         hinfo->cfg.size = size;
 210         if (!hinfo->cfg.max)
 211                 hinfo->cfg.max = 8 * hinfo->cfg.size;
 212         else if (hinfo->cfg.max < hinfo->cfg.size)
 213                 hinfo->cfg.max = hinfo->cfg.size;
 214
 215         for (i = 0; i < hinfo->cfg.size; i++)
 216                 INIT_HLIST_HEAD(&hinfo->hash[i]);
 217
 218         atomic_set(&hinfo->use, 1);
 219         hinfo->count = 0;
 220         hinfo->family = family;
 221         hinfo->rnd_initialized = 0;
 222         spin_lock_init(&hinfo->lock);
 223         hinfo->pde = create_proc_entry(minfo->name, 0,
 224                                        family == AF_INET ? hashlimit_procdir4 :
 225                                                            hashlimit_procdir6);
 226         if (!hinfo->pde) {
 227                 vfree(hinfo);
 228                 return -1;
 229         }
 230         hinfo->pde->proc_fops = &dl_file_ops;
 231         hinfo->pde->data = hinfo;
 232
 233         setup_timer(&hinfo->timer, htable_gc, (unsigned long )hinfo);
 234         hinfo->timer.expires = jiffies + msecs_to_jiffies(hinfo->cfg.gc_interval);
 235         add_timer(&hinfo->timer);
 236
 237         spin_lock_bh(&hashlimit_lock);
 238         hlist_add_head(&hinfo->node, &hashlimit_htables);
 239         spin_unlock_bh(&hashlimit_lock);
 240
 241         return 0;
 242 }
 243
 244 static bool select_all(const struct xt_hashlimit_htable *ht,
 245                        const struct dsthash_ent *he)
 246 {
 247         return 1;
 248 }
 249
 250 static bool select_gc(const struct xt_hashlimit_htable *ht,
 251                       const struct dsthash_ent *he)
 252 {
 253         return time_after_eq(jiffies, he->expires);
 254 }
 255
 256 static void htable_selective_cleanup(struct xt_hashlimit_htable *ht,
 257                         bool (*select)(const struct xt_hashlimit_htable *ht,
 258                                       const struct dsthash_ent *he))
 259 {
 260         unsigned int i;
 261
 262         /* lock hash table and iterate over it */
 263         spin_lock_bh(&ht->lock);
 264         for (i = 0; i < ht->cfg.size; i++) {
 265                 struct dsthash_ent *dh;
 266                 struct hlist_node *pos, *n;
 267                 hlist_for_each_entry_safe(dh, pos, n, &ht->hash[i], node) {
 268                         if ((*select)(ht, dh))
 269                                 dsthash_free(ht, dh);
 270                 }
 271         }
 272         spin_unlock_bh(&ht->lock);
 273 }
 274
 275 /* hash table garbage collector, run by timer */
 276 static void htable_gc(unsigned long htlong)
 277 {
 278         struct xt_hashlimit_htable *ht = (struct xt_hashlimit_htable *)htlong;
 279
 280         htable_selective_cleanup(ht, select_gc);
 281
 282         /* re-add the timer accordingly */
 283         ht->timer.expires = jiffies + msecs_to_jiffies(ht->cfg.gc_interval);
 284         add_timer(&ht->timer);
 285 }
 286
 287 static void htable_destroy(struct xt_hashlimit_htable *hinfo)
 288 {
 289         /* remove timer, if it is pending */
 290         if (timer_pending(&hinfo->timer))
 291                 del_timer(&hinfo->timer);
 292
 293         /* remove proc entry */
 294         remove_proc_entry(hinfo->pde->name,
 295                           hinfo->family == AF_INET ? hashlimit_procdir4 :
 296                                                      hashlimit_procdir6);
 297         htable_selective_cleanup(hinfo, select_all);
 298         vfree(hinfo);
 299 }
 300
 301 static struct xt_hashlimit_htable *htable_find_get(const char *name,
 302                                                    int family)
 303 {
 304         struct xt_hashlimit_htable *hinfo;
 305         struct hlist_node *pos;
 306
 307         spin_lock_bh(&hashlimit_lock);
 308         hlist_for_each_entry(hinfo, pos, &hashlimit_htables, node) {
 309                 if (!strcmp(name, hinfo->pde->name) &&
 310                     hinfo->family == family) {
 311                         atomic_inc(&hinfo->use);
 312                         spin_unlock_bh(&hashlimit_lock);
 313                         return hinfo;
 314                 }
 315         }
 316         spin_unlock_bh(&hashlimit_lock);
 317         return NULL;
 318 }
 319
 320 static void htable_put(struct xt_hashlimit_htable *hinfo)
 321 {
 322         if (atomic_dec_and_test(&hinfo->use)) {
 323                 spin_lock_bh(&hashlimit_lock);
 324                 hlist_del(&hinfo->node);
 325                 spin_unlock_bh(&hashlimit_lock);
 326                 htable_destroy(hinfo);
 327         }
 328 }
 329
 330 /* The algorithm used is the Simple Token Bucket Filter (TBF)
 331  * see net/sched/sch_tbf.c in the linux source tree
 332  */
 333
 334 /* Rusty: This is my (non-mathematically-inclined) understanding of
 335    this algorithm.  The `average rate' in jiffies becomes your initial
 336    amount of credit `credit' and the most credit you can ever have
 337    `credit_cap'.  The `peak rate' becomes the cost of passing the
 338    test, `cost'.
 339
 340    `prev' tracks the last packet hit: you gain one credit per jiffy.
 341    If you get credit balance more than this, the extra credit is
 342    discarded.  Every time the match passes, you lose `cost' credits;
 343    if you don't have that many, the test fails.
 344
 345    See Alexey's formal explanation in net/sched/sch_tbf.c.
 346
 347    To get the maximum range, we multiply by this factor (ie. you get N
 348    credits per jiffy).  We want to allow a rate as low as 1 per day
 349    (slowest userspace tool allows), which means
 350    CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
 351 */
 352 #define MAX_CPJ (0xFFFFFFFF / (HZ*60*60*24))
 353
 354 /* Repeated shift and or gives us all 1s, final shift and add 1 gives
 355  * us the power of 2 below the theoretical max, so GCC simply does a
 356  * shift. */
 357 #define _POW2_BELOW2(x) ((x)|((x)>>1))
 358 #define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
 359 #define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
 360 #define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
 361 #define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
 362 #define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
 363
 364 #define CREDITS_PER_JIFFY POW2_BELOW32(MAX_CPJ)
 365
 366 /* Precision saver. */
 367 static inline u_int32_t
 368 user2credits(u_int32_t user)
 369 {
 370         /* If multiplying would overflow... */
 371         if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY))
 372                 /* Divide first. */
 373                 return (user / XT_HASHLIMIT_SCALE) * HZ * CREDITS_PER_JIFFY;
 374
 375         return (user * HZ * CREDITS_PER_JIFFY) / XT_HASHLIMIT_SCALE;
 376 }
 377
 378 static inline void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now)
 379 {
 380         dh->rateinfo.credit += (now - dh->rateinfo.prev) * CREDITS_PER_JIFFY;
 381         if (dh->rateinfo.credit > dh->rateinfo.credit_cap)
 382                 dh->rateinfo.credit = dh->rateinfo.credit_cap;
 383         dh->rateinfo.prev = now;
 384 }
 385
 386 static int
 387 hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
 388                    struct dsthash_dst *dst,
 389                    const struct sk_buff *skb, unsigned int protoff)
 390 {
 391         __be16 _ports[2], *ports;
 392         u8 nexthdr;
 393
 394         memset(dst, 0, sizeof(*dst));
 395
 396         switch (hinfo->family) {
 397         case AF_INET:
 398                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
 399                         dst->addr.ip.dst = ip_hdr(skb)->daddr;
 400                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
 401                         dst->addr.ip.src = ip_hdr(skb)->saddr;
 402
 403                 if (!(hinfo->cfg.mode &
 404                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
 405                         return 0;
 406                 nexthdr = ip_hdr(skb)->protocol;
 407                 break;
 408 #if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
 409         case AF_INET6:
 410                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
 411                         memcpy(&dst->addr.ip6.dst, &ipv6_hdr(skb)->daddr,
 412                                sizeof(dst->addr.ip6.dst));
 413                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
 414                         memcpy(&dst->addr.ip6.src, &ipv6_hdr(skb)->saddr,
 415                                sizeof(dst->addr.ip6.src));
 416
 417                 if (!(hinfo->cfg.mode &
 418                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
 419                         return 0;
 420                 nexthdr = ipv6_hdr(skb)->nexthdr;
 421                 protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr);
 422                 if ((int)protoff < 0)
 423                         return -1;
 424                 break;
 425 #endif
 426         default:
 427                 BUG();
 428                 return 0;
 429         }
 430
 431         switch (nexthdr) {
 432         case IPPROTO_TCP:
 433         case IPPROTO_UDP:
 434         case IPPROTO_UDPLITE:
 435         case IPPROTO_SCTP:
 436         case IPPROTO_DCCP:
 437                 ports = skb_header_pointer(skb, protoff, sizeof(_ports),
 438                                            &_ports);
 439                 break;
 440         default:
 441                 _ports[0] = _ports[1] = 0;
 442                 ports = _ports;
 443                 break;
 444         }
 445         if (!ports)
 446                 return -1;
 447         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT)
 448                 dst->src_port = ports[0];
 449         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT)
 450                 dst->dst_port = ports[1];
 451         return 0;
 452 }
 453
 454 static bool
 455 hashlimit_mt(const struct sk_buff *skb, const struct net_device *in,
 456              const struct net_device *out, const struct xt_match *match,
 457              const void *matchinfo, int offset, unsigned int protoff,
 458              bool *hotdrop)
 459 {
 460         const struct xt_hashlimit_info *r =
 461                 ((const struct xt_hashlimit_info *)matchinfo)->u.master;
 462         struct xt_hashlimit_htable *hinfo = r->hinfo;
 463         unsigned long now = jiffies;
 464         struct dsthash_ent *dh;
 465         struct dsthash_dst dst;
 466
 467         if (hashlimit_init_dst(hinfo, &dst, skb, protoff) < 0)
 468                 goto hotdrop;
 469
 470         spin_lock_bh(&hinfo->lock);
 471         dh = dsthash_find(hinfo, &dst);
 472         if (!dh) {
 473                 dh = dsthash_alloc_init(hinfo, &dst);
 474                 if (!dh) {
 475                         spin_unlock_bh(&hinfo->lock);
 476                         goto hotdrop;
 477                 }
 478
 479                 dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
 480                 dh->rateinfo.prev = jiffies;
 481                 dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
 482                                                    hinfo->cfg.burst);
 483                 dh->rateinfo.credit_cap = user2credits(hinfo->cfg.avg *
 484                                                        hinfo->cfg.burst);
 485                 dh->rateinfo.cost = user2credits(hinfo->cfg.avg);
 486         } else {
 487                 /* update expiration timeout */
 488                 dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
 489                 rateinfo_recalc(dh, now);
 490         }
 491
 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 true;
 497         }
 498
 499         spin_unlock_bh(&hinfo->lock);
 500
 501         /* default case: we're overlimit, thus don't match */
 502         return false;
 503
 504 hotdrop:
 505         *hotdrop = true;
 506         return false;
 507 }
 508
 509 static bool
 510 hashlimit_mt_check(const char *tablename, const void *inf,
 511                    const struct xt_match *match, void *matchinfo,
 512                    unsigned int hook_mask)
 513 {
 514         struct xt_hashlimit_info *r = matchinfo;
 515
 516         /* Check for overflow. */
 517         if (r->cfg.burst == 0 ||
 518             user2credits(r->cfg.avg * r->cfg.burst) < user2credits(r->cfg.avg)) {
 519                 printk(KERN_ERR "xt_hashlimit: overflow, try lower: %u/%u\n",
 520                        r->cfg.avg, r->cfg.burst);
 521                 return false;
 522         }
 523         if (r->cfg.mode == 0 ||
 524             r->cfg.mode > (XT_HASHLIMIT_HASH_DPT |
 525                            XT_HASHLIMIT_HASH_DIP |
 526                            XT_HASHLIMIT_HASH_SIP |
 527                            XT_HASHLIMIT_HASH_SPT))
 528                 return false;
 529         if (!r->cfg.gc_interval)
 530                 return false;
 531         if (!r->cfg.expire)
 532                 return false;
 533         if (r->name[sizeof(r->name) - 1] != '\0')
 534                 return false;
 535
 536         /* This is the best we've got: We cannot release and re-grab lock,
 537          * since checkentry() is called before x_tables.c grabs xt_mutex.
 538          * We also cannot grab the hashtable spinlock, since htable_create will
 539          * call vmalloc, and that can sleep.  And we cannot just re-search
 540          * the list of htable's in htable_create(), since then we would
 541          * create duplicate proc files. -HW */
 542         mutex_lock(&hlimit_mutex);
 543         r->hinfo = htable_find_get(r->name, match->family);
 544         if (!r->hinfo && htable_create(r, match->family) != 0) {
 545                 mutex_unlock(&hlimit_mutex);
 546                 return false;
 547         }
 548         mutex_unlock(&hlimit_mutex);
 549
 550         /* Ugly hack: For SMP, we only want to use one set */
 551         r->u.master = r;
 552         return true;
 553 }
 554
 555 static void
 556 hashlimit_mt_destroy(const struct xt_match *match, void *matchinfo)
 557 {
 558         const struct xt_hashlimit_info *r = matchinfo;
 559
 560         htable_put(r->hinfo);
 561 }
 562
 563 #ifdef CONFIG_COMPAT
 564 struct compat_xt_hashlimit_info {
 565         char name[IFNAMSIZ];
 566         struct hashlimit_cfg cfg;
 567         compat_uptr_t hinfo;
 568         compat_uptr_t master;
 569 };
 570
 571 static void hashlimit_mt_compat_from_user(void *dst, void *src)
 572 {
 573         int off = offsetof(struct compat_xt_hashlimit_info, hinfo);
 574
 575         memcpy(dst, src, off);
 576         memset(dst + off, 0, sizeof(struct compat_xt_hashlimit_info) - off);
 577 }
 578
 579 static int hashlimit_mt_compat_to_user(void __user *dst, void *src)
 580 {
 581         int off = offsetof(struct compat_xt_hashlimit_info, hinfo);
 582
 583         return copy_to_user(dst, src, off) ? -EFAULT : 0;
 584 }
 585 #endif
 586
 587 static struct xt_match hashlimit_mt_reg[] __read_mostly = {
 588         {
 589                 .name           = "hashlimit",
 590                 .family         = AF_INET,
 591                 .match          = hashlimit_mt,
 592                 .matchsize      = sizeof(struct xt_hashlimit_info),
 593 #ifdef CONFIG_COMPAT
 594                 .compatsize     = sizeof(struct compat_xt_hashlimit_info),
 595                 .compat_from_user = hashlimit_mt_compat_from_user,
 596                 .compat_to_user = hashlimit_mt_compat_to_user,
 597 #endif
 598                 .checkentry     = hashlimit_mt_check,
 599                 .destroy        = hashlimit_mt_destroy,
 600                 .me             = THIS_MODULE
 601         },
 602         {
 603                 .name           = "hashlimit",
 604                 .family         = AF_INET6,
 605                 .match          = hashlimit_mt,
 606                 .matchsize      = sizeof(struct xt_hashlimit_info),
 607 #ifdef CONFIG_COMPAT
 608                 .compatsize     = sizeof(struct compat_xt_hashlimit_info),
 609                 .compat_from_user = hashlimit_mt_compat_from_user,
 610                 .compat_to_user = hashlimit_mt_compat_to_user,
 611 #endif
 612                 .checkentry     = hashlimit_mt_check,
 613                 .destroy        = hashlimit_mt_destroy,
 614                 .me             = THIS_MODULE
 615         },
 616 };
 617
 618 /* PROC stuff */
 619 static void *dl_seq_start(struct seq_file *s, loff_t *pos)
 620 {
 621         struct proc_dir_entry *pde = s->private;
 622         struct xt_hashlimit_htable *htable = pde->data;
 623         unsigned int *bucket;
 624
 625         spin_lock_bh(&htable->lock);
 626         if (*pos >= htable->cfg.size)
 627                 return NULL;
 628
 629         bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
 630         if (!bucket)
 631                 return ERR_PTR(-ENOMEM);
 632
 633         *bucket = *pos;
 634         return bucket;
 635 }
 636
 637 static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
 638 {
 639         struct proc_dir_entry *pde = s->private;
 640         struct xt_hashlimit_htable *htable = pde->data;
 641         unsigned int *bucket = (unsigned int *)v;
 642
 643         *pos = ++(*bucket);
 644         if (*pos >= htable->cfg.size) {
 645                 kfree(v);
 646                 return NULL;
 647         }
 648         return bucket;
 649 }
 650
 651 static void dl_seq_stop(struct seq_file *s, void *v)
 652 {
 653         struct proc_dir_entry *pde = s->private;
 654         struct xt_hashlimit_htable *htable = pde->data;
 655         unsigned int *bucket = (unsigned int *)v;
 656
 657         kfree(bucket);
 658         spin_unlock_bh(&htable->lock);
 659 }
 660
 661 static int dl_seq_real_show(struct dsthash_ent *ent, int family,
 662                                    struct seq_file *s)
 663 {
 664         /* recalculate to show accurate numbers */
 665         rateinfo_recalc(ent, jiffies);
 666
 667         switch (family) {
 668         case AF_INET:
 669                 return seq_printf(s, "%ld %u.%u.%u.%u:%u->"
 670                                      "%u.%u.%u.%u:%u %u %u %u\n",
 671                                  (long)(ent->expires - jiffies)/HZ,
 672                                  NIPQUAD(ent->dst.addr.ip.src),
 673                                  ntohs(ent->dst.src_port),
 674                                  NIPQUAD(ent->dst.addr.ip.dst),
 675                                  ntohs(ent->dst.dst_port),
 676                                  ent->rateinfo.credit, ent->rateinfo.credit_cap,
 677                                  ent->rateinfo.cost);
 678         case AF_INET6:
 679                 return seq_printf(s, "%ld " NIP6_FMT ":%u->"
 680                                      NIP6_FMT ":%u %u %u %u\n",
 681                                  (long)(ent->expires - jiffies)/HZ,
 682                                  NIP6(*(struct in6_addr *)&ent->dst.addr.ip6.src),
 683                                  ntohs(ent->dst.src_port),
 684                                  NIP6(*(struct in6_addr *)&ent->dst.addr.ip6.dst),
 685                                  ntohs(ent->dst.dst_port),
 686                                  ent->rateinfo.credit, ent->rateinfo.credit_cap,
 687                                  ent->rateinfo.cost);
 688         default:
 689                 BUG();
 690                 return 0;
 691         }
 692 }
 693
 694 static int dl_seq_show(struct seq_file *s, void *v)
 695 {
 696         struct proc_dir_entry *pde = s->private;
 697         struct xt_hashlimit_htable *htable = pde->data;
 698         unsigned int *bucket = (unsigned int *)v;
 699         struct dsthash_ent *ent;
 700         struct hlist_node *pos;
 701
 702         if (!hlist_empty(&htable->hash[*bucket])) {
 703                 hlist_for_each_entry(ent, pos, &htable->hash[*bucket], node)
 704                         if (dl_seq_real_show(ent, htable->family, s))
 705                                 return 1;
 706         }
 707         return 0;
 708 }
 709
 710 static const struct seq_operations dl_seq_ops = {
 711         .start = dl_seq_start,
 712         .next  = dl_seq_next,
 713         .stop  = dl_seq_stop,
 714         .show  = dl_seq_show
 715 };
 716
 717 static int dl_proc_open(struct inode *inode, struct file *file)
 718 {
 719         int ret = seq_open(file, &dl_seq_ops);
 720
 721         if (!ret) {
 722                 struct seq_file *sf = file->private_data;
 723                 sf->private = PDE(inode);
 724         }
 725         return ret;
 726 }
 727
 728 static const struct file_operations dl_file_ops = {
 729         .owner   = THIS_MODULE,
 730         .open    = dl_proc_open,
 731         .read    = seq_read,
 732         .llseek  = seq_lseek,
 733         .release = seq_release
 734 };
 735
 736 static int __init hashlimit_mt_init(void)
 737 {
 738         int err;
 739
 740         err = xt_register_matches(hashlimit_mt_reg,
 741               ARRAY_SIZE(hashlimit_mt_reg));
 742         if (err < 0)
 743                 goto err1;
 744
 745         err = -ENOMEM;
 746         hashlimit_cachep = kmem_cache_create("xt_hashlimit",
 747                                             sizeof(struct dsthash_ent), 0, 0,
 748                                             NULL);
 749         if (!hashlimit_cachep) {
 750                 printk(KERN_ERR "xt_hashlimit: unable to create slab cache\n");
 751                 goto err2;
 752         }
 753         hashlimit_procdir4 = proc_mkdir("ipt_hashlimit", init_net.proc_net);
 754         if (!hashlimit_procdir4) {
 755                 printk(KERN_ERR "xt_hashlimit: unable to create proc dir "
 756                                 "entry\n");
 757                 goto err3;
 758         }
 759         hashlimit_procdir6 = proc_mkdir("ip6t_hashlimit", init_net.proc_net);
 760         if (!hashlimit_procdir6) {
 761                 printk(KERN_ERR "xt_hashlimit: unable to create proc dir "
 762                                 "entry\n");
 763                 goto err4;
 764         }
 765         return 0;
 766 err4:
 767         remove_proc_entry("ipt_hashlimit", init_net.proc_net);
 768 err3:
 769         kmem_cache_destroy(hashlimit_cachep);
 770 err2:
 771         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
 772 err1:
 773         return err;
 774
 775 }
 776
 777 static void __exit hashlimit_mt_exit(void)
 778 {
 779         remove_proc_entry("ipt_hashlimit", init_net.proc_net);
 780         remove_proc_entry("ip6t_hashlimit", init_net.proc_net);
 781         kmem_cache_destroy(hashlimit_cachep);
 782         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
 783 }
 784
 785 module_init(hashlimit_mt_init);
 786 module_exit(hashlimit_mt_exit);