linux/net/netfilter/xt_hashlimit.c
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   1/*
   2 *      xt_hashlimit - Netfilter module to limit the number of packets per time
   3 *      separately for each hashbucket (sourceip/sourceport/dstip/dstport)
   4 *
   5 *      (C) 2003-2004 by Harald Welte <laforge@netfilter.org>
   6 *      Copyright © CC Computer Consultants GmbH, 2007 - 2008
   7 *
   8 * Development of this code was funded by Astaro AG, http://www.astaro.com/
   9 */
  10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11#include <linux/module.h>
  12#include <linux/spinlock.h>
  13#include <linux/random.h>
  14#include <linux/jhash.h>
  15#include <linux/slab.h>
  16#include <linux/vmalloc.h>
  17#include <linux/proc_fs.h>
  18#include <linux/seq_file.h>
  19#include <linux/list.h>
  20#include <linux/skbuff.h>
  21#include <linux/mm.h>
  22#include <linux/in.h>
  23#include <linux/ip.h>
  24#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
  25#include <linux/ipv6.h>
  26#include <net/ipv6.h>
  27#endif
  28
  29#include <net/net_namespace.h>
  30#include <net/netns/generic.h>
  31
  32#include <linux/netfilter/x_tables.h>
  33#include <linux/netfilter_ipv4/ip_tables.h>
  34#include <linux/netfilter_ipv6/ip6_tables.h>
  35#include <linux/netfilter/xt_hashlimit.h>
  36#include <linux/mutex.h>
  37
  38MODULE_LICENSE("GPL");
  39MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  40MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
  41MODULE_DESCRIPTION("Xtables: per hash-bucket rate-limit match");
  42MODULE_ALIAS("ipt_hashlimit");
  43MODULE_ALIAS("ip6t_hashlimit");
  44
  45struct hashlimit_net {
  46        struct hlist_head       htables;
  47        struct proc_dir_entry   *ipt_hashlimit;
  48        struct proc_dir_entry   *ip6t_hashlimit;
  49};
  50
  51static int hashlimit_net_id;
  52static inline struct hashlimit_net *hashlimit_pernet(struct net *net)
  53{
  54        return net_generic(net, hashlimit_net_id);
  55}
  56
  57/* need to declare this at the top */
  58static const struct file_operations dl_file_ops;
  59
  60/* hash table crap */
  61struct dsthash_dst {
  62        union {
  63                struct {
  64                        __be32 src;
  65                        __be32 dst;
  66                } ip;
  67#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
  68                struct {
  69                        __be32 src[4];
  70                        __be32 dst[4];
  71                } ip6;
  72#endif
  73        };
  74        __be16 src_port;
  75        __be16 dst_port;
  76};
  77
  78struct dsthash_ent {
  79        /* static / read-only parts in the beginning */
  80        struct hlist_node node;
  81        struct dsthash_dst dst;
  82
  83        /* modified structure members in the end */
  84        spinlock_t lock;
  85        unsigned long expires;          /* precalculated expiry time */
  86        struct {
  87                unsigned long prev;     /* last modification */
  88                u_int32_t credit;
  89                u_int32_t credit_cap, cost;
  90        } rateinfo;
  91        struct rcu_head rcu;
  92};
  93
  94struct xt_hashlimit_htable {
  95        struct hlist_node node;         /* global list of all htables */
  96        int use;
  97        u_int8_t family;
  98        bool rnd_initialized;
  99
 100        struct hashlimit_cfg1 cfg;      /* config */
 101
 102        /* used internally */
 103        spinlock_t lock;                /* lock for list_head */
 104        u_int32_t rnd;                  /* random seed for hash */
 105        unsigned int count;             /* number entries in table */
 106        struct timer_list timer;        /* timer for gc */
 107
 108        /* seq_file stuff */
 109        struct proc_dir_entry *pde;
 110        struct net *net;
 111
 112        struct hlist_head hash[0];      /* hashtable itself */
 113};
 114
 115static DEFINE_MUTEX(hashlimit_mutex);   /* protects htables list */
 116static struct kmem_cache *hashlimit_cachep __read_mostly;
 117
 118static inline bool dst_cmp(const struct dsthash_ent *ent,
 119                           const struct dsthash_dst *b)
 120{
 121        return !memcmp(&ent->dst, b, sizeof(ent->dst));
 122}
 123
 124static u_int32_t
 125hash_dst(const struct xt_hashlimit_htable *ht, const struct dsthash_dst *dst)
 126{
 127        u_int32_t hash = jhash2((const u32 *)dst,
 128                                sizeof(*dst)/sizeof(u32),
 129                                ht->rnd);
 130        /*
 131         * Instead of returning hash % ht->cfg.size (implying a divide)
 132         * we return the high 32 bits of the (hash * ht->cfg.size) that will
 133         * give results between [0 and cfg.size-1] and same hash distribution,
 134         * but using a multiply, less expensive than a divide
 135         */
 136        return ((u64)hash * ht->cfg.size) >> 32;
 137}
 138
 139static struct dsthash_ent *
 140dsthash_find(const struct xt_hashlimit_htable *ht,
 141             const struct dsthash_dst *dst)
 142{
 143        struct dsthash_ent *ent;
 144        struct hlist_node *pos;
 145        u_int32_t hash = hash_dst(ht, dst);
 146
 147        if (!hlist_empty(&ht->hash[hash])) {
 148                hlist_for_each_entry_rcu(ent, pos, &ht->hash[hash], node)
 149                        if (dst_cmp(ent, dst)) {
 150                                spin_lock(&ent->lock);
 151                                return ent;
 152                        }
 153        }
 154        return NULL;
 155}
 156
 157/* allocate dsthash_ent, initialize dst, put in htable and lock it */
 158static struct dsthash_ent *
 159dsthash_alloc_init(struct xt_hashlimit_htable *ht,
 160                   const struct dsthash_dst *dst)
 161{
 162        struct dsthash_ent *ent;
 163
 164        spin_lock(&ht->lock);
 165        /* initialize hash with random val at the time we allocate
 166         * the first hashtable entry */
 167        if (unlikely(!ht->rnd_initialized)) {
 168                get_random_bytes(&ht->rnd, sizeof(ht->rnd));
 169                ht->rnd_initialized = true;
 170        }
 171
 172        if (ht->cfg.max && ht->count >= ht->cfg.max) {
 173                /* FIXME: do something. question is what.. */
 174                if (net_ratelimit())
 175                        pr_err("max count of %u reached\n", ht->cfg.max);
 176                ent = NULL;
 177        } else
 178                ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
 179        if (!ent) {
 180                if (net_ratelimit())
 181                        pr_err("cannot allocate dsthash_ent\n");
 182        } else {
 183                memcpy(&ent->dst, dst, sizeof(ent->dst));
 184                spin_lock_init(&ent->lock);
 185
 186                spin_lock(&ent->lock);
 187                hlist_add_head_rcu(&ent->node, &ht->hash[hash_dst(ht, dst)]);
 188                ht->count++;
 189        }
 190        spin_unlock(&ht->lock);
 191        return ent;
 192}
 193
 194static void dsthash_free_rcu(struct rcu_head *head)
 195{
 196        struct dsthash_ent *ent = container_of(head, struct dsthash_ent, rcu);
 197
 198        kmem_cache_free(hashlimit_cachep, ent);
 199}
 200
 201static inline void
 202dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent)
 203{
 204        hlist_del_rcu(&ent->node);
 205        call_rcu_bh(&ent->rcu, dsthash_free_rcu);
 206        ht->count--;
 207}
 208static void htable_gc(unsigned long htlong);
 209
 210static int htable_create(struct net *net, struct xt_hashlimit_mtinfo1 *minfo,
 211                         u_int8_t family)
 212{
 213        struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
 214        struct xt_hashlimit_htable *hinfo;
 215        unsigned int size;
 216        unsigned int i;
 217
 218        if (minfo->cfg.size) {
 219                size = minfo->cfg.size;
 220        } else {
 221                size = (totalram_pages << PAGE_SHIFT) / 16384 /
 222                       sizeof(struct list_head);
 223                if (totalram_pages > 1024 * 1024 * 1024 / PAGE_SIZE)
 224                        size = 8192;
 225                if (size < 16)
 226                        size = 16;
 227        }
 228        /* FIXME: don't use vmalloc() here or anywhere else -HW */
 229        hinfo = vmalloc(sizeof(struct xt_hashlimit_htable) +
 230                        sizeof(struct list_head) * size);
 231        if (hinfo == NULL)
 232                return -ENOMEM;
 233        minfo->hinfo = hinfo;
 234
 235        /* copy match config into hashtable config */
 236        memcpy(&hinfo->cfg, &minfo->cfg, sizeof(hinfo->cfg));
 237        hinfo->cfg.size = size;
 238        if (hinfo->cfg.max == 0)
 239                hinfo->cfg.max = 8 * hinfo->cfg.size;
 240        else if (hinfo->cfg.max < hinfo->cfg.size)
 241                hinfo->cfg.max = hinfo->cfg.size;
 242
 243        for (i = 0; i < hinfo->cfg.size; i++)
 244                INIT_HLIST_HEAD(&hinfo->hash[i]);
 245
 246        hinfo->use = 1;
 247        hinfo->count = 0;
 248        hinfo->family = family;
 249        hinfo->rnd_initialized = false;
 250        spin_lock_init(&hinfo->lock);
 251
 252        hinfo->pde = proc_create_data(minfo->name, 0,
 253                (family == NFPROTO_IPV4) ?
 254                hashlimit_net->ipt_hashlimit : hashlimit_net->ip6t_hashlimit,
 255                &dl_file_ops, hinfo);
 256        if (hinfo->pde == NULL) {
 257                vfree(hinfo);
 258                return -ENOMEM;
 259        }
 260        hinfo->net = net;
 261
 262        setup_timer(&hinfo->timer, htable_gc, (unsigned long)hinfo);
 263        hinfo->timer.expires = jiffies + msecs_to_jiffies(hinfo->cfg.gc_interval);
 264        add_timer(&hinfo->timer);
 265
 266        hlist_add_head(&hinfo->node, &hashlimit_net->htables);
 267
 268        return 0;
 269}
 270
 271static bool select_all(const struct xt_hashlimit_htable *ht,
 272                       const struct dsthash_ent *he)
 273{
 274        return 1;
 275}
 276
 277static bool select_gc(const struct xt_hashlimit_htable *ht,
 278                      const struct dsthash_ent *he)
 279{
 280        return time_after_eq(jiffies, he->expires);
 281}
 282
 283static void htable_selective_cleanup(struct xt_hashlimit_htable *ht,
 284                        bool (*select)(const struct xt_hashlimit_htable *ht,
 285                                      const struct dsthash_ent *he))
 286{
 287        unsigned int i;
 288
 289        /* lock hash table and iterate over it */
 290        spin_lock_bh(&ht->lock);
 291        for (i = 0; i < ht->cfg.size; i++) {
 292                struct dsthash_ent *dh;
 293                struct hlist_node *pos, *n;
 294                hlist_for_each_entry_safe(dh, pos, n, &ht->hash[i], node) {
 295                        if ((*select)(ht, dh))
 296                                dsthash_free(ht, dh);
 297                }
 298        }
 299        spin_unlock_bh(&ht->lock);
 300}
 301
 302/* hash table garbage collector, run by timer */
 303static void htable_gc(unsigned long htlong)
 304{
 305        struct xt_hashlimit_htable *ht = (struct xt_hashlimit_htable *)htlong;
 306
 307        htable_selective_cleanup(ht, select_gc);
 308
 309        /* re-add the timer accordingly */
 310        ht->timer.expires = jiffies + msecs_to_jiffies(ht->cfg.gc_interval);
 311        add_timer(&ht->timer);
 312}
 313
 314static void htable_destroy(struct xt_hashlimit_htable *hinfo)
 315{
 316        struct hashlimit_net *hashlimit_net = hashlimit_pernet(hinfo->net);
 317        struct proc_dir_entry *parent;
 318
 319        del_timer_sync(&hinfo->timer);
 320
 321        if (hinfo->family == NFPROTO_IPV4)
 322                parent = hashlimit_net->ipt_hashlimit;
 323        else
 324                parent = hashlimit_net->ip6t_hashlimit;
 325        remove_proc_entry(hinfo->pde->name, parent);
 326        htable_selective_cleanup(hinfo, select_all);
 327        vfree(hinfo);
 328}
 329
 330static struct xt_hashlimit_htable *htable_find_get(struct net *net,
 331                                                   const char *name,
 332                                                   u_int8_t family)
 333{
 334        struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
 335        struct xt_hashlimit_htable *hinfo;
 336        struct hlist_node *pos;
 337
 338        hlist_for_each_entry(hinfo, pos, &hashlimit_net->htables, node) {
 339                if (!strcmp(name, hinfo->pde->name) &&
 340                    hinfo->family == family) {
 341                        hinfo->use++;
 342                        return hinfo;
 343                }
 344        }
 345        return NULL;
 346}
 347
 348static void htable_put(struct xt_hashlimit_htable *hinfo)
 349{
 350        mutex_lock(&hashlimit_mutex);
 351        if (--hinfo->use == 0) {
 352                hlist_del(&hinfo->node);
 353                htable_destroy(hinfo);
 354        }
 355        mutex_unlock(&hashlimit_mutex);
 356}
 357
 358/* The algorithm used is the Simple Token Bucket Filter (TBF)
 359 * see net/sched/sch_tbf.c in the linux source tree
 360 */
 361
 362/* Rusty: This is my (non-mathematically-inclined) understanding of
 363   this algorithm.  The `average rate' in jiffies becomes your initial
 364   amount of credit `credit' and the most credit you can ever have
 365   `credit_cap'.  The `peak rate' becomes the cost of passing the
 366   test, `cost'.
 367
 368   `prev' tracks the last packet hit: you gain one credit per jiffy.
 369   If you get credit balance more than this, the extra credit is
 370   discarded.  Every time the match passes, you lose `cost' credits;
 371   if you don't have that many, the test fails.
 372
 373   See Alexey's formal explanation in net/sched/sch_tbf.c.
 374
 375   To get the maximum range, we multiply by this factor (ie. you get N
 376   credits per jiffy).  We want to allow a rate as low as 1 per day
 377   (slowest userspace tool allows), which means
 378   CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
 379*/
 380#define MAX_CPJ (0xFFFFFFFF / (HZ*60*60*24))
 381
 382/* Repeated shift and or gives us all 1s, final shift and add 1 gives
 383 * us the power of 2 below the theoretical max, so GCC simply does a
 384 * shift. */
 385#define _POW2_BELOW2(x) ((x)|((x)>>1))
 386#define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
 387#define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
 388#define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
 389#define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
 390#define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
 391
 392#define CREDITS_PER_JIFFY POW2_BELOW32(MAX_CPJ)
 393
 394/* Precision saver. */
 395static inline u_int32_t
 396user2credits(u_int32_t user)
 397{
 398        /* If multiplying would overflow... */
 399        if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY))
 400                /* Divide first. */
 401                return (user / XT_HASHLIMIT_SCALE) * HZ * CREDITS_PER_JIFFY;
 402
 403        return (user * HZ * CREDITS_PER_JIFFY) / XT_HASHLIMIT_SCALE;
 404}
 405
 406static inline void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now)
 407{
 408        dh->rateinfo.credit += (now - dh->rateinfo.prev) * CREDITS_PER_JIFFY;
 409        if (dh->rateinfo.credit > dh->rateinfo.credit_cap)
 410                dh->rateinfo.credit = dh->rateinfo.credit_cap;
 411        dh->rateinfo.prev = now;
 412}
 413
 414static inline __be32 maskl(__be32 a, unsigned int l)
 415{
 416        return l ? htonl(ntohl(a) & ~0 << (32 - l)) : 0;
 417}
 418
 419#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
 420static void hashlimit_ipv6_mask(__be32 *i, unsigned int p)
 421{
 422        switch (p) {
 423        case 0 ... 31:
 424                i[0] = maskl(i[0], p);
 425                i[1] = i[2] = i[3] = 0;
 426                break;
 427        case 32 ... 63:
 428                i[1] = maskl(i[1], p - 32);
 429                i[2] = i[3] = 0;
 430                break;
 431        case 64 ... 95:
 432                i[2] = maskl(i[2], p - 64);
 433                i[3] = 0;
 434                break;
 435        case 96 ... 127:
 436                i[3] = maskl(i[3], p - 96);
 437                break;
 438        case 128:
 439                break;
 440        }
 441}
 442#endif
 443
 444static int
 445hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
 446                   struct dsthash_dst *dst,
 447                   const struct sk_buff *skb, unsigned int protoff)
 448{
 449        __be16 _ports[2], *ports;
 450        u8 nexthdr;
 451
 452        memset(dst, 0, sizeof(*dst));
 453
 454        switch (hinfo->family) {
 455        case NFPROTO_IPV4:
 456                if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
 457                        dst->ip.dst = maskl(ip_hdr(skb)->daddr,
 458                                      hinfo->cfg.dstmask);
 459                if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
 460                        dst->ip.src = maskl(ip_hdr(skb)->saddr,
 461                                      hinfo->cfg.srcmask);
 462
 463                if (!(hinfo->cfg.mode &
 464                      (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
 465                        return 0;
 466                nexthdr = ip_hdr(skb)->protocol;
 467                break;
 468#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
 469        case NFPROTO_IPV6:
 470                if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) {
 471                        memcpy(&dst->ip6.dst, &ipv6_hdr(skb)->daddr,
 472                               sizeof(dst->ip6.dst));
 473                        hashlimit_ipv6_mask(dst->ip6.dst, hinfo->cfg.dstmask);
 474                }
 475                if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) {
 476                        memcpy(&dst->ip6.src, &ipv6_hdr(skb)->saddr,
 477                               sizeof(dst->ip6.src));
 478                        hashlimit_ipv6_mask(dst->ip6.src, hinfo->cfg.srcmask);
 479                }
 480
 481                if (!(hinfo->cfg.mode &
 482                      (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
 483                        return 0;
 484                nexthdr = ipv6_hdr(skb)->nexthdr;
 485                protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr);
 486                if ((int)protoff < 0)
 487                        return -1;
 488                break;
 489#endif
 490        default:
 491                BUG();
 492                return 0;
 493        }
 494
 495        switch (nexthdr) {
 496        case IPPROTO_TCP:
 497        case IPPROTO_UDP:
 498        case IPPROTO_UDPLITE:
 499        case IPPROTO_SCTP:
 500        case IPPROTO_DCCP:
 501                ports = skb_header_pointer(skb, protoff, sizeof(_ports),
 502                                           &_ports);
 503                break;
 504        default:
 505                _ports[0] = _ports[1] = 0;
 506                ports = _ports;
 507                break;
 508        }
 509        if (!ports)
 510                return -1;
 511        if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT)
 512                dst->src_port = ports[0];
 513        if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT)
 514                dst->dst_port = ports[1];
 515        return 0;
 516}
 517
 518static bool
 519hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par)
 520{
 521        const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
 522        struct xt_hashlimit_htable *hinfo = info->hinfo;
 523        unsigned long now = jiffies;
 524        struct dsthash_ent *dh;
 525        struct dsthash_dst dst;
 526
 527        if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0)
 528                goto hotdrop;
 529
 530        rcu_read_lock_bh();
 531        dh = dsthash_find(hinfo, &dst);
 532        if (dh == NULL) {
 533                dh = dsthash_alloc_init(hinfo, &dst);
 534                if (dh == NULL) {
 535                        rcu_read_unlock_bh();
 536                        goto hotdrop;
 537                }
 538                dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
 539                dh->rateinfo.prev = jiffies;
 540                dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
 541                                      hinfo->cfg.burst);
 542                dh->rateinfo.credit_cap = user2credits(hinfo->cfg.avg *
 543                                          hinfo->cfg.burst);
 544                dh->rateinfo.cost = user2credits(hinfo->cfg.avg);
 545        } else {
 546                /* update expiration timeout */
 547                dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
 548                rateinfo_recalc(dh, now);
 549        }
 550
 551        if (dh->rateinfo.credit >= dh->rateinfo.cost) {
 552                /* below the limit */
 553                dh->rateinfo.credit -= dh->rateinfo.cost;
 554                spin_unlock(&dh->lock);
 555                rcu_read_unlock_bh();
 556                return !(info->cfg.mode & XT_HASHLIMIT_INVERT);
 557        }
 558
 559        spin_unlock(&dh->lock);
 560        rcu_read_unlock_bh();
 561        /* default match is underlimit - so over the limit, we need to invert */
 562        return info->cfg.mode & XT_HASHLIMIT_INVERT;
 563
 564 hotdrop:
 565        par->hotdrop = true;
 566        return false;
 567}
 568
 569static int hashlimit_mt_check(const struct xt_mtchk_param *par)
 570{
 571        struct net *net = par->net;
 572        struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
 573        int ret;
 574
 575        /* Check for overflow. */
 576        if (info->cfg.burst == 0 ||
 577            user2credits(info->cfg.avg * info->cfg.burst) <
 578            user2credits(info->cfg.avg)) {
 579                pr_info("overflow, try lower: %u/%u\n",
 580                        info->cfg.avg, info->cfg.burst);
 581                return -ERANGE;
 582        }
 583        if (info->cfg.gc_interval == 0 || info->cfg.expire == 0)
 584                return -EINVAL;
 585        if (info->name[sizeof(info->name)-1] != '\0')
 586                return -EINVAL;
 587        if (par->family == NFPROTO_IPV4) {
 588                if (info->cfg.srcmask > 32 || info->cfg.dstmask > 32)
 589                        return -EINVAL;
 590        } else {
 591                if (info->cfg.srcmask > 128 || info->cfg.dstmask > 128)
 592                        return -EINVAL;
 593        }
 594
 595        mutex_lock(&hashlimit_mutex);
 596        info->hinfo = htable_find_get(net, info->name, par->family);
 597        if (info->hinfo == NULL) {
 598                ret = htable_create(net, info, par->family);
 599                if (ret < 0) {
 600                        mutex_unlock(&hashlimit_mutex);
 601                        return ret;
 602                }
 603        }
 604        mutex_unlock(&hashlimit_mutex);
 605        return 0;
 606}
 607
 608static void hashlimit_mt_destroy(const struct xt_mtdtor_param *par)
 609{
 610        const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
 611
 612        htable_put(info->hinfo);
 613}
 614
 615static struct xt_match hashlimit_mt_reg[] __read_mostly = {
 616        {
 617                .name           = "hashlimit",
 618                .revision       = 1,
 619                .family         = NFPROTO_IPV4,
 620                .match          = hashlimit_mt,
 621                .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
 622                .checkentry     = hashlimit_mt_check,
 623                .destroy        = hashlimit_mt_destroy,
 624                .me             = THIS_MODULE,
 625        },
 626#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
 627        {
 628                .name           = "hashlimit",
 629                .revision       = 1,
 630                .family         = NFPROTO_IPV6,
 631                .match          = hashlimit_mt,
 632                .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
 633                .checkentry     = hashlimit_mt_check,
 634                .destroy        = hashlimit_mt_destroy,
 635                .me             = THIS_MODULE,
 636        },
 637#endif
 638};
 639
 640/* PROC stuff */
 641static void *dl_seq_start(struct seq_file *s, loff_t *pos)
 642        __acquires(htable->lock)
 643{
 644        struct xt_hashlimit_htable *htable = s->private;
 645        unsigned int *bucket;
 646
 647        spin_lock_bh(&htable->lock);
 648        if (*pos >= htable->cfg.size)
 649                return NULL;
 650
 651        bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
 652        if (!bucket)
 653                return ERR_PTR(-ENOMEM);
 654
 655        *bucket = *pos;
 656        return bucket;
 657}
 658
 659static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
 660{
 661        struct xt_hashlimit_htable *htable = s->private;
 662        unsigned int *bucket = (unsigned int *)v;
 663
 664        *pos = ++(*bucket);
 665        if (*pos >= htable->cfg.size) {
 666                kfree(v);
 667                return NULL;
 668        }
 669        return bucket;
 670}
 671
 672static void dl_seq_stop(struct seq_file *s, void *v)
 673        __releases(htable->lock)
 674{
 675        struct xt_hashlimit_htable *htable = s->private;
 676        unsigned int *bucket = (unsigned int *)v;
 677
 678        if (!IS_ERR(bucket))
 679                kfree(bucket);
 680        spin_unlock_bh(&htable->lock);
 681}
 682
 683static int dl_seq_real_show(struct dsthash_ent *ent, u_int8_t family,
 684                                   struct seq_file *s)
 685{
 686        int res;
 687
 688        spin_lock(&ent->lock);
 689        /* recalculate to show accurate numbers */
 690        rateinfo_recalc(ent, jiffies);
 691
 692        switch (family) {
 693        case NFPROTO_IPV4:
 694                res = seq_printf(s, "%ld %pI4:%u->%pI4:%u %u %u %u\n",
 695                                 (long)(ent->expires - jiffies)/HZ,
 696                                 &ent->dst.ip.src,
 697                                 ntohs(ent->dst.src_port),
 698                                 &ent->dst.ip.dst,
 699                                 ntohs(ent->dst.dst_port),
 700                                 ent->rateinfo.credit, ent->rateinfo.credit_cap,
 701                                 ent->rateinfo.cost);
 702                break;
 703#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
 704        case NFPROTO_IPV6:
 705                res = seq_printf(s, "%ld %pI6:%u->%pI6:%u %u %u %u\n",
 706                                 (long)(ent->expires - jiffies)/HZ,
 707                                 &ent->dst.ip6.src,
 708                                 ntohs(ent->dst.src_port),
 709                                 &ent->dst.ip6.dst,
 710                                 ntohs(ent->dst.dst_port),
 711                                 ent->rateinfo.credit, ent->rateinfo.credit_cap,
 712                                 ent->rateinfo.cost);
 713                break;
 714#endif
 715        default:
 716                BUG();
 717                res = 0;
 718        }
 719        spin_unlock(&ent->lock);
 720        return res;
 721}
 722
 723static int dl_seq_show(struct seq_file *s, void *v)
 724{
 725        struct xt_hashlimit_htable *htable = s->private;
 726        unsigned int *bucket = (unsigned int *)v;
 727        struct dsthash_ent *ent;
 728        struct hlist_node *pos;
 729
 730        if (!hlist_empty(&htable->hash[*bucket])) {
 731                hlist_for_each_entry(ent, pos, &htable->hash[*bucket], node)
 732                        if (dl_seq_real_show(ent, htable->family, s))
 733                                return -1;
 734        }
 735        return 0;
 736}
 737
 738static const struct seq_operations dl_seq_ops = {
 739        .start = dl_seq_start,
 740        .next  = dl_seq_next,
 741        .stop  = dl_seq_stop,
 742        .show  = dl_seq_show
 743};
 744
 745static int dl_proc_open(struct inode *inode, struct file *file)
 746{
 747        int ret = seq_open(file, &dl_seq_ops);
 748
 749        if (!ret) {
 750                struct seq_file *sf = file->private_data;
 751                sf->private = PDE(inode)->data;
 752        }
 753        return ret;
 754}
 755
 756static const struct file_operations dl_file_ops = {
 757        .owner   = THIS_MODULE,
 758        .open    = dl_proc_open,
 759        .read    = seq_read,
 760        .llseek  = seq_lseek,
 761        .release = seq_release
 762};
 763
 764static int __net_init hashlimit_proc_net_init(struct net *net)
 765{
 766        struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
 767
 768        hashlimit_net->ipt_hashlimit = proc_mkdir("ipt_hashlimit", net->proc_net);
 769        if (!hashlimit_net->ipt_hashlimit)
 770                return -ENOMEM;
 771#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
 772        hashlimit_net->ip6t_hashlimit = proc_mkdir("ip6t_hashlimit", net->proc_net);
 773        if (!hashlimit_net->ip6t_hashlimit) {
 774                proc_net_remove(net, "ipt_hashlimit");
 775                return -ENOMEM;
 776        }
 777#endif
 778        return 0;
 779}
 780
 781static void __net_exit hashlimit_proc_net_exit(struct net *net)
 782{
 783        proc_net_remove(net, "ipt_hashlimit");
 784#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
 785        proc_net_remove(net, "ip6t_hashlimit");
 786#endif
 787}
 788
 789static int __net_init hashlimit_net_init(struct net *net)
 790{
 791        struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
 792
 793        INIT_HLIST_HEAD(&hashlimit_net->htables);
 794        return hashlimit_proc_net_init(net);
 795}
 796
 797static void __net_exit hashlimit_net_exit(struct net *net)
 798{
 799        struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
 800
 801        BUG_ON(!hlist_empty(&hashlimit_net->htables));
 802        hashlimit_proc_net_exit(net);
 803}
 804
 805static struct pernet_operations hashlimit_net_ops = {
 806        .init   = hashlimit_net_init,
 807        .exit   = hashlimit_net_exit,
 808        .id     = &hashlimit_net_id,
 809        .size   = sizeof(struct hashlimit_net),
 810};
 811
 812static int __init hashlimit_mt_init(void)
 813{
 814        int err;
 815
 816        err = register_pernet_subsys(&hashlimit_net_ops);
 817        if (err < 0)
 818                return err;
 819        err = xt_register_matches(hashlimit_mt_reg,
 820              ARRAY_SIZE(hashlimit_mt_reg));
 821        if (err < 0)
 822                goto err1;
 823
 824        err = -ENOMEM;
 825        hashlimit_cachep = kmem_cache_create("xt_hashlimit",
 826                                            sizeof(struct dsthash_ent), 0, 0,
 827                                            NULL);
 828        if (!hashlimit_cachep) {
 829                pr_warning("unable to create slab cache\n");
 830                goto err2;
 831        }
 832        return 0;
 833
 834err2:
 835        xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
 836err1:
 837        unregister_pernet_subsys(&hashlimit_net_ops);
 838        return err;
 839
 840}
 841
 842static void __exit hashlimit_mt_exit(void)
 843{
 844        xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
 845        unregister_pernet_subsys(&hashlimit_net_ops);
 846
 847        rcu_barrier_bh();
 848        kmem_cache_destroy(hashlimit_cachep);
 849}
 850
 851module_init(hashlimit_mt_init);
 852module_exit(hashlimit_mt_exit);
 853
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