net/netfilter/xt_hashlimit.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *      xt_hashlimit - Netfilter module to limit the number of packets per time
   4  *      separately for each hashbucket (sourceip/sourceport/dstip/dstport)
   5  *
   6  *      (C) 2003-2004 by Harald Welte <laforge@netfilter.org>
   7  *      (C) 2006-2012 Patrick McHardy <kaber@trash.net>
   8  *      Copyright © CC Computer Consultants GmbH, 2007 - 2008
   9  *
  10  * Development of this code was funded by Astaro AG, http://www.astaro.com/
  11  */
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13 #include <linux/module.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/random.h>
  16 #include <linux/jhash.h>
  17 #include <linux/slab.h>
  18 #include <linux/vmalloc.h>
  19 #include <linux/proc_fs.h>
  20 #include <linux/seq_file.h>
  21 #include <linux/list.h>
  22 #include <linux/skbuff.h>
  23 #include <linux/mm.h>
  24 #include <linux/in.h>
  25 #include <linux/ip.h>
  26 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
  27 #include <linux/ipv6.h>
  28 #include <net/ipv6.h>
  29 #endif
  30
  31 #include <net/net_namespace.h>
  32 #include <net/netns/generic.h>
  33
  34 #include <linux/netfilter/x_tables.h>
  35 #include <linux/netfilter_ipv4/ip_tables.h>
  36 #include <linux/netfilter_ipv6/ip6_tables.h>
  37 #include <linux/mutex.h>
  38 #include <linux/kernel.h>
  39 #include <linux/refcount.h>
  40 #include <uapi/linux/netfilter/xt_hashlimit.h>
  41
  42 #define XT_HASHLIMIT_ALL (XT_HASHLIMIT_HASH_DIP | XT_HASHLIMIT_HASH_DPT | \
  43                           XT_HASHLIMIT_HASH_SIP | XT_HASHLIMIT_HASH_SPT | \
  44                           XT_HASHLIMIT_INVERT | XT_HASHLIMIT_BYTES |\
  45                           XT_HASHLIMIT_RATE_MATCH)
  46
  47 MODULE_LICENSE("GPL");
  48 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  49 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
  50 MODULE_DESCRIPTION("Xtables: per hash-bucket rate-limit match");
  51 MODULE_ALIAS("ipt_hashlimit");
  52 MODULE_ALIAS("ip6t_hashlimit");
  53
  54 struct hashlimit_net {
  55         struct hlist_head       htables;
  56         struct proc_dir_entry   *ipt_hashlimit;
  57         struct proc_dir_entry   *ip6t_hashlimit;
  58 };
  59
  60 static unsigned int hashlimit_net_id;
  61 static inline struct hashlimit_net *hashlimit_pernet(struct net *net)
  62 {
  63         return net_generic(net, hashlimit_net_id);
  64 }
  65
  66 /* need to declare this at the top */
  67 static const struct seq_operations dl_seq_ops_v2;
  68 static const struct seq_operations dl_seq_ops_v1;
  69 static const struct seq_operations dl_seq_ops;
  70
  71 /* hash table crap */
  72 struct dsthash_dst {
  73         union {
  74                 struct {
  75                         __be32 src;
  76                         __be32 dst;
  77                 } ip;
  78 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
  79                 struct {
  80                         __be32 src[4];
  81                         __be32 dst[4];
  82                 } ip6;
  83 #endif
  84         };
  85         __be16 src_port;
  86         __be16 dst_port;
  87 };
  88
  89 struct dsthash_ent {
  90         /* static / read-only parts in the beginning */
  91         struct hlist_node node;
  92         struct dsthash_dst dst;
  93
  94         /* modified structure members in the end */
  95         spinlock_t lock;
  96         unsigned long expires;          /* precalculated expiry time */
  97         struct {
  98                 unsigned long prev;     /* last modification */
  99                 union {
 100                         struct {
 101                                 u_int64_t credit;
 102                                 u_int64_t credit_cap;
 103                                 u_int64_t cost;
 104                         };
 105                         struct {
 106                                 u_int32_t interval, prev_window;
 107                                 u_int64_t current_rate;
 108                                 u_int64_t rate;
 109                                 int64_t burst;
 110                         };
 111                 };
 112         } rateinfo;
 113         struct rcu_head rcu;
 114 };
 115
 116 struct xt_hashlimit_htable {
 117         struct hlist_node node;         /* global list of all htables */
 118         refcount_t use;
 119         u_int8_t family;
 120         bool rnd_initialized;
 121
 122         struct hashlimit_cfg3 cfg;      /* config */
 123
 124         /* used internally */
 125         spinlock_t lock;                /* lock for list_head */
 126         u_int32_t rnd;                  /* random seed for hash */
 127         unsigned int count;             /* number entries in table */
 128         struct delayed_work gc_work;
 129
 130         /* seq_file stuff */
 131         struct proc_dir_entry *pde;
 132         const char *name;
 133         struct net *net;
 134
 135         struct hlist_head hash[0];      /* hashtable itself */
 136 };
 137
 138 static int
 139 cfg_copy(struct hashlimit_cfg3 *to, const void *from, int revision)
 140 {
 141         if (revision == 1) {
 142                 struct hashlimit_cfg1 *cfg = (struct hashlimit_cfg1 *)from;
 143
 144                 to->mode = cfg->mode;
 145                 to->avg = cfg->avg;
 146                 to->burst = cfg->burst;
 147                 to->size = cfg->size;
 148                 to->max = cfg->max;
 149                 to->gc_interval = cfg->gc_interval;
 150                 to->expire = cfg->expire;
 151                 to->srcmask = cfg->srcmask;
 152                 to->dstmask = cfg->dstmask;
 153         } else if (revision == 2) {
 154                 struct hashlimit_cfg2 *cfg = (struct hashlimit_cfg2 *)from;
 155
 156                 to->mode = cfg->mode;
 157                 to->avg = cfg->avg;
 158                 to->burst = cfg->burst;
 159                 to->size = cfg->size;
 160                 to->max = cfg->max;
 161                 to->gc_interval = cfg->gc_interval;
 162                 to->expire = cfg->expire;
 163                 to->srcmask = cfg->srcmask;
 164                 to->dstmask = cfg->dstmask;
 165         } else if (revision == 3) {
 166                 memcpy(to, from, sizeof(struct hashlimit_cfg3));
 167         } else {
 168                 return -EINVAL;
 169         }
 170
 171         return 0;
 172 }
 173
 174 static DEFINE_MUTEX(hashlimit_mutex);   /* protects htables list */
 175 static struct kmem_cache *hashlimit_cachep __read_mostly;
 176
 177 static inline bool dst_cmp(const struct dsthash_ent *ent,
 178                            const struct dsthash_dst *b)
 179 {
 180         return !memcmp(&ent->dst, b, sizeof(ent->dst));
 181 }
 182
 183 static u_int32_t
 184 hash_dst(const struct xt_hashlimit_htable *ht, const struct dsthash_dst *dst)
 185 {
 186         u_int32_t hash = jhash2((const u32 *)dst,
 187                                 sizeof(*dst)/sizeof(u32),
 188                                 ht->rnd);
 189         /*
 190          * Instead of returning hash % ht->cfg.size (implying a divide)
 191          * we return the high 32 bits of the (hash * ht->cfg.size) that will
 192          * give results between [0 and cfg.size-1] and same hash distribution,
 193          * but using a multiply, less expensive than a divide
 194          */
 195         return reciprocal_scale(hash, ht->cfg.size);
 196 }
 197
 198 static struct dsthash_ent *
 199 dsthash_find(const struct xt_hashlimit_htable *ht,
 200              const struct dsthash_dst *dst)
 201 {
 202         struct dsthash_ent *ent;
 203         u_int32_t hash = hash_dst(ht, dst);
 204
 205         if (!hlist_empty(&ht->hash[hash])) {
 206                 hlist_for_each_entry_rcu(ent, &ht->hash[hash], node)
 207                         if (dst_cmp(ent, dst)) {
 208                                 spin_lock(&ent->lock);
 209                                 return ent;
 210                         }
 211         }
 212         return NULL;
 213 }
 214
 215 /* allocate dsthash_ent, initialize dst, put in htable and lock it */
 216 static struct dsthash_ent *
 217 dsthash_alloc_init(struct xt_hashlimit_htable *ht,
 218                    const struct dsthash_dst *dst, bool *race)
 219 {
 220         struct dsthash_ent *ent;
 221
 222         spin_lock(&ht->lock);
 223
 224         /* Two or more packets may race to create the same entry in the
 225          * hashtable, double check if this packet lost race.
 226          */
 227         ent = dsthash_find(ht, dst);
 228         if (ent != NULL) {
 229                 spin_unlock(&ht->lock);
 230                 *race = true;
 231                 return ent;
 232         }
 233
 234         /* initialize hash with random val at the time we allocate
 235          * the first hashtable entry */
 236         if (unlikely(!ht->rnd_initialized)) {
 237                 get_random_bytes(&ht->rnd, sizeof(ht->rnd));
 238                 ht->rnd_initialized = true;
 239         }
 240
 241         if (ht->cfg.max && ht->count >= ht->cfg.max) {
 242                 /* FIXME: do something. question is what.. */
 243                 net_err_ratelimited("max count of %u reached\n", ht->cfg.max);
 244                 ent = NULL;
 245         } else
 246                 ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
 247         if (ent) {
 248                 memcpy(&ent->dst, dst, sizeof(ent->dst));
 249                 spin_lock_init(&ent->lock);
 250
 251                 spin_lock(&ent->lock);
 252                 hlist_add_head_rcu(&ent->node, &ht->hash[hash_dst(ht, dst)]);
 253                 ht->count++;
 254         }
 255         spin_unlock(&ht->lock);
 256         return ent;
 257 }
 258
 259 static void dsthash_free_rcu(struct rcu_head *head)
 260 {
 261         struct dsthash_ent *ent = container_of(head, struct dsthash_ent, rcu);
 262
 263         kmem_cache_free(hashlimit_cachep, ent);
 264 }
 265
 266 static inline void
 267 dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent)
 268 {
 269         hlist_del_rcu(&ent->node);
 270         call_rcu(&ent->rcu, dsthash_free_rcu);
 271         ht->count--;
 272 }
 273 static void htable_gc(struct work_struct *work);
 274
 275 static int htable_create(struct net *net, struct hashlimit_cfg3 *cfg,
 276                          const char *name, u_int8_t family,
 277                          struct xt_hashlimit_htable **out_hinfo,
 278                          int revision)
 279 {
 280         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
 281         struct xt_hashlimit_htable *hinfo;
 282         const struct seq_operations *ops;
 283         unsigned int size, i;
 284         unsigned long nr_pages = totalram_pages();
 285         int ret;
 286
 287         if (cfg->size) {
 288                 size = cfg->size;
 289         } else {
 290                 size = (nr_pages << PAGE_SHIFT) / 16384 /
 291                        sizeof(struct hlist_head);
 292                 if (nr_pages > 1024 * 1024 * 1024 / PAGE_SIZE)
 293                         size = 8192;
 294                 if (size < 16)
 295                         size = 16;
 296         }
 297         /* FIXME: don't use vmalloc() here or anywhere else -HW */
 298         hinfo = vmalloc(struct_size(hinfo, hash, size));
 299         if (hinfo == NULL)
 300                 return -ENOMEM;
 301         *out_hinfo = hinfo;
 302
 303         /* copy match config into hashtable config */
 304         ret = cfg_copy(&hinfo->cfg, (void *)cfg, 3);
 305         if (ret) {
 306                 vfree(hinfo);
 307                 return ret;
 308         }
 309
 310         hinfo->cfg.size = size;
 311         if (hinfo->cfg.max == 0)
 312                 hinfo->cfg.max = 8 * hinfo->cfg.size;
 313         else if (hinfo->cfg.max < hinfo->cfg.size)
 314                 hinfo->cfg.max = hinfo->cfg.size;
 315
 316         for (i = 0; i < hinfo->cfg.size; i++)
 317                 INIT_HLIST_HEAD(&hinfo->hash[i]);
 318
 319         refcount_set(&hinfo->use, 1);
 320         hinfo->count = 0;
 321         hinfo->family = family;
 322         hinfo->rnd_initialized = false;
 323         hinfo->name = kstrdup(name, GFP_KERNEL);
 324         if (!hinfo->name) {
 325                 vfree(hinfo);
 326                 return -ENOMEM;
 327         }
 328         spin_lock_init(&hinfo->lock);
 329
 330         switch (revision) {
 331         case 1:
 332                 ops = &dl_seq_ops_v1;
 333                 break;
 334         case 2:
 335                 ops = &dl_seq_ops_v2;
 336                 break;
 337         default:
 338                 ops = &dl_seq_ops;
 339         }
 340
 341         hinfo->pde = proc_create_seq_data(name, 0,
 342                 (family == NFPROTO_IPV4) ?
 343                 hashlimit_net->ipt_hashlimit : hashlimit_net->ip6t_hashlimit,
 344                 ops, hinfo);
 345         if (hinfo->pde == NULL) {
 346                 kfree(hinfo->name);
 347                 vfree(hinfo);
 348                 return -ENOMEM;
 349         }
 350         hinfo->net = net;
 351
 352         INIT_DEFERRABLE_WORK(&hinfo->gc_work, htable_gc);
 353         queue_delayed_work(system_power_efficient_wq, &hinfo->gc_work,
 354                            msecs_to_jiffies(hinfo->cfg.gc_interval));
 355
 356         hlist_add_head(&hinfo->node, &hashlimit_net->htables);
 357
 358         return 0;
 359 }
 360
 361 static void htable_selective_cleanup(struct xt_hashlimit_htable *ht, bool select_all)
 362 {
 363         unsigned int i;
 364
 365         for (i = 0; i < ht->cfg.size; i++) {
 366                 struct dsthash_ent *dh;
 367                 struct hlist_node *n;
 368
 369                 spin_lock_bh(&ht->lock);
 370                 hlist_for_each_entry_safe(dh, n, &ht->hash[i], node) {
 371                         if (time_after_eq(jiffies, dh->expires) || select_all)
 372                                 dsthash_free(ht, dh);
 373                 }
 374                 spin_unlock_bh(&ht->lock);
 375                 cond_resched();
 376         }
 377 }
 378
 379 static void htable_gc(struct work_struct *work)
 380 {
 381         struct xt_hashlimit_htable *ht;
 382
 383         ht = container_of(work, struct xt_hashlimit_htable, gc_work.work);
 384
 385         htable_selective_cleanup(ht, false);
 386
 387         queue_delayed_work(system_power_efficient_wq,
 388                            &ht->gc_work, msecs_to_jiffies(ht->cfg.gc_interval));
 389 }
 390
 391 static void htable_remove_proc_entry(struct xt_hashlimit_htable *hinfo)
 392 {
 393         struct hashlimit_net *hashlimit_net = hashlimit_pernet(hinfo->net);
 394         struct proc_dir_entry *parent;
 395
 396         if (hinfo->family == NFPROTO_IPV4)
 397                 parent = hashlimit_net->ipt_hashlimit;
 398         else
 399                 parent = hashlimit_net->ip6t_hashlimit;
 400
 401         if (parent != NULL)
 402                 remove_proc_entry(hinfo->name, parent);
 403 }
 404
 405 static void htable_destroy(struct xt_hashlimit_htable *hinfo)
 406 {
 407         cancel_delayed_work_sync(&hinfo->gc_work);
 408         htable_remove_proc_entry(hinfo);
 409         htable_selective_cleanup(hinfo, true);
 410         kfree(hinfo->name);
 411         vfree(hinfo);
 412 }
 413
 414 static struct xt_hashlimit_htable *htable_find_get(struct net *net,
 415                                                    const char *name,
 416                                                    u_int8_t family)
 417 {
 418         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
 419         struct xt_hashlimit_htable *hinfo;
 420
 421         hlist_for_each_entry(hinfo, &hashlimit_net->htables, node) {
 422                 if (!strcmp(name, hinfo->name) &&
 423                     hinfo->family == family) {
 424                         refcount_inc(&hinfo->use);
 425                         return hinfo;
 426                 }
 427         }
 428         return NULL;
 429 }
 430
 431 static void htable_put(struct xt_hashlimit_htable *hinfo)
 432 {
 433         if (refcount_dec_and_mutex_lock(&hinfo->use, &hashlimit_mutex)) {
 434                 hlist_del(&hinfo->node);
 435                 mutex_unlock(&hashlimit_mutex);
 436                 htable_destroy(hinfo);
 437         }
 438 }
 439
 440 /* The algorithm used is the Simple Token Bucket Filter (TBF)
 441  * see net/sched/sch_tbf.c in the linux source tree
 442  */
 443
 444 /* Rusty: This is my (non-mathematically-inclined) understanding of
 445    this algorithm.  The `average rate' in jiffies becomes your initial
 446    amount of credit `credit' and the most credit you can ever have
 447    `credit_cap'.  The `peak rate' becomes the cost of passing the
 448    test, `cost'.
 449
 450    `prev' tracks the last packet hit: you gain one credit per jiffy.
 451    If you get credit balance more than this, the extra credit is
 452    discarded.  Every time the match passes, you lose `cost' credits;
 453    if you don't have that many, the test fails.
 454
 455    See Alexey's formal explanation in net/sched/sch_tbf.c.
 456
 457    To get the maximum range, we multiply by this factor (ie. you get N
 458    credits per jiffy).  We want to allow a rate as low as 1 per day
 459    (slowest userspace tool allows), which means
 460    CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
 461 */
 462 #define MAX_CPJ_v1 (0xFFFFFFFF / (HZ*60*60*24))
 463 #define MAX_CPJ (0xFFFFFFFFFFFFFFFFULL / (HZ*60*60*24))
 464
 465 /* Repeated shift and or gives us all 1s, final shift and add 1 gives
 466  * us the power of 2 below the theoretical max, so GCC simply does a
 467  * shift. */
 468 #define _POW2_BELOW2(x) ((x)|((x)>>1))
 469 #define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
 470 #define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
 471 #define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
 472 #define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
 473 #define _POW2_BELOW64(x) (_POW2_BELOW32(x)|_POW2_BELOW32((x)>>32))
 474 #define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
 475 #define POW2_BELOW64(x) ((_POW2_BELOW64(x)>>1) + 1)
 476
 477 #define CREDITS_PER_JIFFY POW2_BELOW64(MAX_CPJ)
 478 #define CREDITS_PER_JIFFY_v1 POW2_BELOW32(MAX_CPJ_v1)
 479
 480 /* in byte mode, the lowest possible rate is one packet/second.
 481  * credit_cap is used as a counter that tells us how many times we can
 482  * refill the "credits available" counter when it becomes empty.
 483  */
 484 #define MAX_CPJ_BYTES (0xFFFFFFFF / HZ)
 485 #define CREDITS_PER_JIFFY_BYTES POW2_BELOW32(MAX_CPJ_BYTES)
 486
 487 static u32 xt_hashlimit_len_to_chunks(u32 len)
 488 {
 489         return (len >> XT_HASHLIMIT_BYTE_SHIFT) + 1;
 490 }
 491
 492 /* Precision saver. */
 493 static u64 user2credits(u64 user, int revision)
 494 {
 495         u64 scale = (revision == 1) ?
 496                 XT_HASHLIMIT_SCALE : XT_HASHLIMIT_SCALE_v2;
 497         u64 cpj = (revision == 1) ?
 498                 CREDITS_PER_JIFFY_v1 : CREDITS_PER_JIFFY;
 499
 500         /* Avoid overflow: divide the constant operands first */
 501         if (scale >= HZ * cpj)
 502                 return div64_u64(user, div64_u64(scale, HZ * cpj));
 503
 504         return user * div64_u64(HZ * cpj, scale);
 505 }
 506
 507 static u32 user2credits_byte(u32 user)
 508 {
 509         u64 us = user;
 510         us *= HZ * CREDITS_PER_JIFFY_BYTES;
 511         return (u32) (us >> 32);
 512 }
 513
 514 static u64 user2rate(u64 user)
 515 {
 516         if (user != 0) {
 517                 return div64_u64(XT_HASHLIMIT_SCALE_v2, user);
 518         } else {
 519                 pr_info_ratelimited("invalid rate from userspace: %llu\n",
 520                                     user);
 521                 return 0;
 522         }
 523 }
 524
 525 static u64 user2rate_bytes(u32 user)
 526 {
 527         u64 r;
 528
 529         r = user ? U32_MAX / user : U32_MAX;
 530         return (r - 1) << XT_HASHLIMIT_BYTE_SHIFT;
 531 }
 532
 533 static void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now,
 534                             u32 mode, int revision)
 535 {
 536         unsigned long delta = now - dh->rateinfo.prev;
 537         u64 cap, cpj;
 538
 539         if (delta == 0)
 540                 return;
 541
 542         if (revision >= 3 && mode & XT_HASHLIMIT_RATE_MATCH) {
 543                 u64 interval = dh->rateinfo.interval * HZ;
 544
 545                 if (delta < interval)
 546                         return;
 547
 548                 dh->rateinfo.prev = now;
 549                 dh->rateinfo.prev_window =
 550                         ((dh->rateinfo.current_rate * interval) >
 551                          (delta * dh->rateinfo.rate));
 552                 dh->rateinfo.current_rate = 0;
 553
 554                 return;
 555         }
 556
 557         dh->rateinfo.prev = now;
 558
 559         if (mode & XT_HASHLIMIT_BYTES) {
 560                 u64 tmp = dh->rateinfo.credit;
 561                 dh->rateinfo.credit += CREDITS_PER_JIFFY_BYTES * delta;
 562                 cap = CREDITS_PER_JIFFY_BYTES * HZ;
 563                 if (tmp >= dh->rateinfo.credit) {/* overflow */
 564                         dh->rateinfo.credit = cap;
 565                         return;
 566                 }
 567         } else {
 568                 cpj = (revision == 1) ?
 569                         CREDITS_PER_JIFFY_v1 : CREDITS_PER_JIFFY;
 570                 dh->rateinfo.credit += delta * cpj;
 571                 cap = dh->rateinfo.credit_cap;
 572         }
 573         if (dh->rateinfo.credit > cap)
 574                 dh->rateinfo.credit = cap;
 575 }
 576
 577 static void rateinfo_init(struct dsthash_ent *dh,
 578                           struct xt_hashlimit_htable *hinfo, int revision)
 579 {
 580         dh->rateinfo.prev = jiffies;
 581         if (revision >= 3 && hinfo->cfg.mode & XT_HASHLIMIT_RATE_MATCH) {
 582                 dh->rateinfo.prev_window = 0;
 583                 dh->rateinfo.current_rate = 0;
 584                 if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) {
 585                         dh->rateinfo.rate =
 586                                 user2rate_bytes((u32)hinfo->cfg.avg);
 587                         if (hinfo->cfg.burst)
 588                                 dh->rateinfo.burst =
 589                                         hinfo->cfg.burst * dh->rateinfo.rate;
 590                         else
 591                                 dh->rateinfo.burst = dh->rateinfo.rate;
 592                 } else {
 593                         dh->rateinfo.rate = user2rate(hinfo->cfg.avg);
 594                         dh->rateinfo.burst =
 595                                 hinfo->cfg.burst + dh->rateinfo.rate;
 596                 }
 597                 dh->rateinfo.interval = hinfo->cfg.interval;
 598         } else if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) {
 599                 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
 600                 dh->rateinfo.cost = user2credits_byte(hinfo->cfg.avg);
 601                 dh->rateinfo.credit_cap = hinfo->cfg.burst;
 602         } else {
 603                 dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
 604                                                    hinfo->cfg.burst, revision);
 605                 dh->rateinfo.cost = user2credits(hinfo->cfg.avg, revision);
 606                 dh->rateinfo.credit_cap = dh->rateinfo.credit;
 607         }
 608 }
 609
 610 static inline __be32 maskl(__be32 a, unsigned int l)
 611 {
 612         return l ? htonl(ntohl(a) & ~0 << (32 - l)) : 0;
 613 }
 614
 615 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 616 static void hashlimit_ipv6_mask(__be32 *i, unsigned int p)
 617 {
 618         switch (p) {
 619         case 0 ... 31:
 620                 i[0] = maskl(i[0], p);
 621                 i[1] = i[2] = i[3] = 0;
 622                 break;
 623         case 32 ... 63:
 624                 i[1] = maskl(i[1], p - 32);
 625                 i[2] = i[3] = 0;
 626                 break;
 627         case 64 ... 95:
 628                 i[2] = maskl(i[2], p - 64);
 629                 i[3] = 0;
 630                 break;
 631         case 96 ... 127:
 632                 i[3] = maskl(i[3], p - 96);
 633                 break;
 634         case 128:
 635                 break;
 636         }
 637 }
 638 #endif
 639
 640 static int
 641 hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
 642                    struct dsthash_dst *dst,
 643                    const struct sk_buff *skb, unsigned int protoff)
 644 {
 645         __be16 _ports[2], *ports;
 646         u8 nexthdr;
 647         int poff;
 648
 649         memset(dst, 0, sizeof(*dst));
 650
 651         switch (hinfo->family) {
 652         case NFPROTO_IPV4:
 653                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
 654                         dst->ip.dst = maskl(ip_hdr(skb)->daddr,
 655                                       hinfo->cfg.dstmask);
 656                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
 657                         dst->ip.src = maskl(ip_hdr(skb)->saddr,
 658                                       hinfo->cfg.srcmask);
 659
 660                 if (!(hinfo->cfg.mode &
 661                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
 662                         return 0;
 663                 nexthdr = ip_hdr(skb)->protocol;
 664                 break;
 665 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 666         case NFPROTO_IPV6:
 667         {
 668                 __be16 frag_off;
 669
 670                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) {
 671                         memcpy(&dst->ip6.dst, &ipv6_hdr(skb)->daddr,
 672                                sizeof(dst->ip6.dst));
 673                         hashlimit_ipv6_mask(dst->ip6.dst, hinfo->cfg.dstmask);
 674                 }
 675                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) {
 676                         memcpy(&dst->ip6.src, &ipv6_hdr(skb)->saddr,
 677                                sizeof(dst->ip6.src));
 678                         hashlimit_ipv6_mask(dst->ip6.src, hinfo->cfg.srcmask);
 679                 }
 680
 681                 if (!(hinfo->cfg.mode &
 682                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
 683                         return 0;
 684                 nexthdr = ipv6_hdr(skb)->nexthdr;
 685                 protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, &frag_off);
 686                 if ((int)protoff < 0)
 687                         return -1;
 688                 break;
 689         }
 690 #endif
 691         default:
 692                 BUG();
 693                 return 0;
 694         }
 695
 696         poff = proto_ports_offset(nexthdr);
 697         if (poff >= 0) {
 698                 ports = skb_header_pointer(skb, protoff + poff, sizeof(_ports),
 699                                            &_ports);
 700         } else {
 701                 _ports[0] = _ports[1] = 0;
 702                 ports = _ports;
 703         }
 704         if (!ports)
 705                 return -1;
 706         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT)
 707                 dst->src_port = ports[0];
 708         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT)
 709                 dst->dst_port = ports[1];
 710         return 0;
 711 }
 712
 713 static u32 hashlimit_byte_cost(unsigned int len, struct dsthash_ent *dh)
 714 {
 715         u64 tmp = xt_hashlimit_len_to_chunks(len);
 716         tmp = tmp * dh->rateinfo.cost;
 717
 718         if (unlikely(tmp > CREDITS_PER_JIFFY_BYTES * HZ))
 719                 tmp = CREDITS_PER_JIFFY_BYTES * HZ;
 720
 721         if (dh->rateinfo.credit < tmp && dh->rateinfo.credit_cap) {
 722                 dh->rateinfo.credit_cap--;
 723                 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
 724         }
 725         return (u32) tmp;
 726 }
 727
 728 static bool
 729 hashlimit_mt_common(const struct sk_buff *skb, struct xt_action_param *par,
 730                     struct xt_hashlimit_htable *hinfo,
 731                     const struct hashlimit_cfg3 *cfg, int revision)
 732 {
 733         unsigned long now = jiffies;
 734         struct dsthash_ent *dh;
 735         struct dsthash_dst dst;
 736         bool race = false;
 737         u64 cost;
 738
 739         if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0)
 740                 goto hotdrop;
 741
 742         local_bh_disable();
 743         dh = dsthash_find(hinfo, &dst);
 744         if (dh == NULL) {
 745                 dh = dsthash_alloc_init(hinfo, &dst, &race);
 746                 if (dh == NULL) {
 747                         local_bh_enable();
 748                         goto hotdrop;
 749                 } else if (race) {
 750                         /* Already got an entry, update expiration timeout */
 751                         dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
 752                         rateinfo_recalc(dh, now, hinfo->cfg.mode, revision);
 753                 } else {
 754                         dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
 755                         rateinfo_init(dh, hinfo, revision);
 756                 }
 757         } else {
 758                 /* update expiration timeout */
 759                 dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
 760                 rateinfo_recalc(dh, now, hinfo->cfg.mode, revision);
 761         }
 762
 763         if (cfg->mode & XT_HASHLIMIT_RATE_MATCH) {
 764                 cost = (cfg->mode & XT_HASHLIMIT_BYTES) ? skb->len : 1;
 765                 dh->rateinfo.current_rate += cost;
 766
 767                 if (!dh->rateinfo.prev_window &&
 768                     (dh->rateinfo.current_rate <= dh->rateinfo.burst)) {
 769                         spin_unlock(&dh->lock);
 770                         local_bh_enable();
 771                         return !(cfg->mode & XT_HASHLIMIT_INVERT);
 772                 } else {
 773                         goto overlimit;
 774                 }
 775         }
 776
 777         if (cfg->mode & XT_HASHLIMIT_BYTES)
 778                 cost = hashlimit_byte_cost(skb->len, dh);
 779         else
 780                 cost = dh->rateinfo.cost;
 781
 782         if (dh->rateinfo.credit >= cost) {
 783                 /* below the limit */
 784                 dh->rateinfo.credit -= cost;
 785                 spin_unlock(&dh->lock);
 786                 local_bh_enable();
 787                 return !(cfg->mode & XT_HASHLIMIT_INVERT);
 788         }
 789
 790 overlimit:
 791         spin_unlock(&dh->lock);
 792         local_bh_enable();
 793         /* default match is underlimit - so over the limit, we need to invert */
 794         return cfg->mode & XT_HASHLIMIT_INVERT;
 795
 796  hotdrop:
 797         par->hotdrop = true;
 798         return false;
 799 }
 800
 801 static bool
 802 hashlimit_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
 803 {
 804         const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
 805         struct xt_hashlimit_htable *hinfo = info->hinfo;
 806         struct hashlimit_cfg3 cfg = {};
 807         int ret;
 808
 809         ret = cfg_copy(&cfg, (void *)&info->cfg, 1);
 810         if (ret)
 811                 return ret;
 812
 813         return hashlimit_mt_common(skb, par, hinfo, &cfg, 1);
 814 }
 815
 816 static bool
 817 hashlimit_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
 818 {
 819         const struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
 820         struct xt_hashlimit_htable *hinfo = info->hinfo;
 821         struct hashlimit_cfg3 cfg = {};
 822         int ret;
 823
 824         ret = cfg_copy(&cfg, (void *)&info->cfg, 2);
 825         if (ret)
 826                 return ret;
 827
 828         return hashlimit_mt_common(skb, par, hinfo, &cfg, 2);
 829 }
 830
 831 static bool
 832 hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par)
 833 {
 834         const struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
 835         struct xt_hashlimit_htable *hinfo = info->hinfo;
 836
 837         return hashlimit_mt_common(skb, par, hinfo, &info->cfg, 3);
 838 }
 839
 840 static int hashlimit_mt_check_common(const struct xt_mtchk_param *par,
 841                                      struct xt_hashlimit_htable **hinfo,
 842                                      struct hashlimit_cfg3 *cfg,
 843                                      const char *name, int revision)
 844 {
 845         struct net *net = par->net;
 846         int ret;
 847
 848         if (cfg->gc_interval == 0 || cfg->expire == 0)
 849                 return -EINVAL;
 850         if (par->family == NFPROTO_IPV4) {
 851                 if (cfg->srcmask > 32 || cfg->dstmask > 32)
 852                         return -EINVAL;
 853         } else {
 854                 if (cfg->srcmask > 128 || cfg->dstmask > 128)
 855                         return -EINVAL;
 856         }
 857
 858         if (cfg->mode & ~XT_HASHLIMIT_ALL) {
 859                 pr_info_ratelimited("Unknown mode mask %X, kernel too old?\n",
 860                                     cfg->mode);
 861                 return -EINVAL;
 862         }
 863
 864         /* Check for overflow. */
 865         if (revision >= 3 && cfg->mode & XT_HASHLIMIT_RATE_MATCH) {
 866                 if (cfg->avg == 0 || cfg->avg > U32_MAX) {
 867                         pr_info_ratelimited("invalid rate\n");
 868                         return -ERANGE;
 869                 }
 870
 871                 if (cfg->interval == 0) {
 872                         pr_info_ratelimited("invalid interval\n");
 873                         return -EINVAL;
 874                 }
 875         } else if (cfg->mode & XT_HASHLIMIT_BYTES) {
 876                 if (user2credits_byte(cfg->avg) == 0) {
 877                         pr_info_ratelimited("overflow, rate too high: %llu\n",
 878                                             cfg->avg);
 879                         return -EINVAL;
 880                 }
 881         } else if (cfg->burst == 0 ||
 882                    user2credits(cfg->avg * cfg->burst, revision) <
 883                    user2credits(cfg->avg, revision)) {
 884                 pr_info_ratelimited("overflow, try lower: %llu/%llu\n",
 885                                     cfg->avg, cfg->burst);
 886                 return -ERANGE;
 887         }
 888
 889         mutex_lock(&hashlimit_mutex);
 890         *hinfo = htable_find_get(net, name, par->family);
 891         if (*hinfo == NULL) {
 892                 ret = htable_create(net, cfg, name, par->family,
 893                                     hinfo, revision);
 894                 if (ret < 0) {
 895                         mutex_unlock(&hashlimit_mutex);
 896                         return ret;
 897                 }
 898         }
 899         mutex_unlock(&hashlimit_mutex);
 900
 901         return 0;
 902 }
 903
 904 static int hashlimit_mt_check_v1(const struct xt_mtchk_param *par)
 905 {
 906         struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
 907         struct hashlimit_cfg3 cfg = {};
 908         int ret;
 909
 910         ret = xt_check_proc_name(info->name, sizeof(info->name));
 911         if (ret)
 912                 return ret;
 913
 914         ret = cfg_copy(&cfg, (void *)&info->cfg, 1);
 915         if (ret)
 916                 return ret;
 917
 918         return hashlimit_mt_check_common(par, &info->hinfo,
 919                                          &cfg, info->name, 1);
 920 }
 921
 922 static int hashlimit_mt_check_v2(const struct xt_mtchk_param *par)
 923 {
 924         struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
 925         struct hashlimit_cfg3 cfg = {};
 926         int ret;
 927
 928         ret = xt_check_proc_name(info->name, sizeof(info->name));
 929         if (ret)
 930                 return ret;
 931
 932         ret = cfg_copy(&cfg, (void *)&info->cfg, 2);
 933         if (ret)
 934                 return ret;
 935
 936         return hashlimit_mt_check_common(par, &info->hinfo,
 937                                          &cfg, info->name, 2);
 938 }
 939
 940 static int hashlimit_mt_check(const struct xt_mtchk_param *par)
 941 {
 942         struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
 943         int ret;
 944
 945         ret = xt_check_proc_name(info->name, sizeof(info->name));
 946         if (ret)
 947                 return ret;
 948
 949         return hashlimit_mt_check_common(par, &info->hinfo, &info->cfg,
 950                                          info->name, 3);
 951 }
 952
 953 static void hashlimit_mt_destroy_v2(const struct xt_mtdtor_param *par)
 954 {
 955         const struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
 956
 957         htable_put(info->hinfo);
 958 }
 959
 960 static void hashlimit_mt_destroy_v1(const struct xt_mtdtor_param *par)
 961 {
 962         const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
 963
 964         htable_put(info->hinfo);
 965 }
 966
 967 static void hashlimit_mt_destroy(const struct xt_mtdtor_param *par)
 968 {
 969         const struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
 970
 971         htable_put(info->hinfo);
 972 }
 973
 974 static struct xt_match hashlimit_mt_reg[] __read_mostly = {
 975         {
 976                 .name           = "hashlimit",
 977                 .revision       = 1,
 978                 .family         = NFPROTO_IPV4,
 979                 .match          = hashlimit_mt_v1,
 980                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
 981                 .usersize       = offsetof(struct xt_hashlimit_mtinfo1, hinfo),
 982                 .checkentry     = hashlimit_mt_check_v1,
 983                 .destroy        = hashlimit_mt_destroy_v1,
 984                 .me             = THIS_MODULE,
 985         },
 986         {
 987                 .name           = "hashlimit",
 988                 .revision       = 2,
 989                 .family         = NFPROTO_IPV4,
 990                 .match          = hashlimit_mt_v2,
 991                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo2),
 992                 .usersize       = offsetof(struct xt_hashlimit_mtinfo2, hinfo),
 993                 .checkentry     = hashlimit_mt_check_v2,
 994                 .destroy        = hashlimit_mt_destroy_v2,
 995                 .me             = THIS_MODULE,
 996         },
 997         {
 998                 .name           = "hashlimit",
 999                 .revision       = 3,
1000                 .family         = NFPROTO_IPV4,
1001                 .match          = hashlimit_mt,
1002                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo3),
1003                 .usersize       = offsetof(struct xt_hashlimit_mtinfo3, hinfo),
1004                 .checkentry     = hashlimit_mt_check,
1005                 .destroy        = hashlimit_mt_destroy,
1006                 .me             = THIS_MODULE,
1007         },
1008 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1009         {
1010                 .name           = "hashlimit",
1011                 .revision       = 1,
1012                 .family         = NFPROTO_IPV6,
1013                 .match          = hashlimit_mt_v1,
1014                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
1015                 .usersize       = offsetof(struct xt_hashlimit_mtinfo1, hinfo),
1016                 .checkentry     = hashlimit_mt_check_v1,
1017                 .destroy        = hashlimit_mt_destroy_v1,
1018                 .me             = THIS_MODULE,
1019         },
1020         {
1021                 .name           = "hashlimit",
1022                 .revision       = 2,
1023                 .family         = NFPROTO_IPV6,
1024                 .match          = hashlimit_mt_v2,
1025                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo2),
1026                 .usersize       = offsetof(struct xt_hashlimit_mtinfo2, hinfo),
1027                 .checkentry     = hashlimit_mt_check_v2,
1028                 .destroy        = hashlimit_mt_destroy_v2,
1029                 .me             = THIS_MODULE,
1030         },
1031         {
1032                 .name           = "hashlimit",
1033                 .revision       = 3,
1034                 .family         = NFPROTO_IPV6,
1035                 .match          = hashlimit_mt,
1036                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo3),
1037                 .usersize       = offsetof(struct xt_hashlimit_mtinfo3, hinfo),
1038                 .checkentry     = hashlimit_mt_check,
1039                 .destroy        = hashlimit_mt_destroy,
1040                 .me             = THIS_MODULE,
1041         },
1042 #endif
1043 };
1044
1045 /* PROC stuff */
1046 static void *dl_seq_start(struct seq_file *s, loff_t *pos)
1047         __acquires(htable->lock)
1048 {
1049         struct xt_hashlimit_htable *htable = PDE_DATA(file_inode(s->file));
1050         unsigned int *bucket;
1051
1052         spin_lock_bh(&htable->lock);
1053         if (*pos >= htable->cfg.size)
1054                 return NULL;
1055
1056         bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
1057         if (!bucket)
1058                 return ERR_PTR(-ENOMEM);
1059
1060         *bucket = *pos;
1061         return bucket;
1062 }
1063
1064 static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
1065 {
1066         struct xt_hashlimit_htable *htable = PDE_DATA(file_inode(s->file));
1067         unsigned int *bucket = v;
1068
1069         *pos = ++(*bucket);
1070         if (*pos >= htable->cfg.size) {
1071                 kfree(v);
1072                 return NULL;
1073         }
1074         return bucket;
1075 }
1076
1077 static void dl_seq_stop(struct seq_file *s, void *v)
1078         __releases(htable->lock)
1079 {
1080         struct xt_hashlimit_htable *htable = PDE_DATA(file_inode(s->file));
1081         unsigned int *bucket = v;
1082
1083         if (!IS_ERR(bucket))
1084                 kfree(bucket);
1085         spin_unlock_bh(&htable->lock);
1086 }
1087
1088 static void dl_seq_print(struct dsthash_ent *ent, u_int8_t family,
1089                          struct seq_file *s)
1090 {
1091         switch (family) {
1092         case NFPROTO_IPV4:
1093                 seq_printf(s, "%ld %pI4:%u->%pI4:%u %llu %llu %llu\n",
1094                            (long)(ent->expires - jiffies)/HZ,
1095                            &ent->dst.ip.src,
1096                            ntohs(ent->dst.src_port),
1097                            &ent->dst.ip.dst,
1098                            ntohs(ent->dst.dst_port),
1099                            ent->rateinfo.credit, ent->rateinfo.credit_cap,
1100                            ent->rateinfo.cost);
1101                 break;
1102 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1103         case NFPROTO_IPV6:
1104                 seq_printf(s, "%ld %pI6:%u->%pI6:%u %llu %llu %llu\n",
1105                            (long)(ent->expires - jiffies)/HZ,
1106                            &ent->dst.ip6.src,
1107                            ntohs(ent->dst.src_port),
1108                            &ent->dst.ip6.dst,
1109                            ntohs(ent->dst.dst_port),
1110                            ent->rateinfo.credit, ent->rateinfo.credit_cap,
1111                            ent->rateinfo.cost);
1112                 break;
1113 #endif
1114         default:
1115                 BUG();
1116         }
1117 }
1118
1119 static int dl_seq_real_show_v2(struct dsthash_ent *ent, u_int8_t family,
1120                                struct seq_file *s)
1121 {
1122         struct xt_hashlimit_htable *ht = PDE_DATA(file_inode(s->file));
1123
1124         spin_lock(&ent->lock);
1125         /* recalculate to show accurate numbers */
1126         rateinfo_recalc(ent, jiffies, ht->cfg.mode, 2);
1127
1128         dl_seq_print(ent, family, s);
1129
1130         spin_unlock(&ent->lock);
1131         return seq_has_overflowed(s);
1132 }
1133
1134 static int dl_seq_real_show_v1(struct dsthash_ent *ent, u_int8_t family,
1135                                struct seq_file *s)
1136 {
1137         struct xt_hashlimit_htable *ht = PDE_DATA(file_inode(s->file));
1138
1139         spin_lock(&ent->lock);
1140         /* recalculate to show accurate numbers */
1141         rateinfo_recalc(ent, jiffies, ht->cfg.mode, 1);
1142
1143         dl_seq_print(ent, family, s);
1144
1145         spin_unlock(&ent->lock);
1146         return seq_has_overflowed(s);
1147 }
1148
1149 static int dl_seq_real_show(struct dsthash_ent *ent, u_int8_t family,
1150                             struct seq_file *s)
1151 {
1152         struct xt_hashlimit_htable *ht = PDE_DATA(file_inode(s->file));
1153
1154         spin_lock(&ent->lock);
1155         /* recalculate to show accurate numbers */
1156         rateinfo_recalc(ent, jiffies, ht->cfg.mode, 3);
1157
1158         dl_seq_print(ent, family, s);
1159
1160         spin_unlock(&ent->lock);
1161         return seq_has_overflowed(s);
1162 }
1163
1164 static int dl_seq_show_v2(struct seq_file *s, void *v)
1165 {
1166         struct xt_hashlimit_htable *htable = PDE_DATA(file_inode(s->file));
1167         unsigned int *bucket = (unsigned int *)v;
1168         struct dsthash_ent *ent;
1169
1170         if (!hlist_empty(&htable->hash[*bucket])) {
1171                 hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1172                         if (dl_seq_real_show_v2(ent, htable->family, s))
1173                                 return -1;
1174         }
1175         return 0;
1176 }
1177
1178 static int dl_seq_show_v1(struct seq_file *s, void *v)
1179 {
1180         struct xt_hashlimit_htable *htable = PDE_DATA(file_inode(s->file));
1181         unsigned int *bucket = v;
1182         struct dsthash_ent *ent;
1183
1184         if (!hlist_empty(&htable->hash[*bucket])) {
1185                 hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1186                         if (dl_seq_real_show_v1(ent, htable->family, s))
1187                                 return -1;
1188         }
1189         return 0;
1190 }
1191
1192 static int dl_seq_show(struct seq_file *s, void *v)
1193 {
1194         struct xt_hashlimit_htable *htable = PDE_DATA(file_inode(s->file));
1195         unsigned int *bucket = v;
1196         struct dsthash_ent *ent;
1197
1198         if (!hlist_empty(&htable->hash[*bucket])) {
1199                 hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1200                         if (dl_seq_real_show(ent, htable->family, s))
1201                                 return -1;
1202         }
1203         return 0;
1204 }
1205
1206 static const struct seq_operations dl_seq_ops_v1 = {
1207         .start = dl_seq_start,
1208         .next  = dl_seq_next,
1209         .stop  = dl_seq_stop,
1210         .show  = dl_seq_show_v1
1211 };
1212
1213 static const struct seq_operations dl_seq_ops_v2 = {
1214         .start = dl_seq_start,
1215         .next  = dl_seq_next,
1216         .stop  = dl_seq_stop,
1217         .show  = dl_seq_show_v2
1218 };
1219
1220 static const struct seq_operations dl_seq_ops = {
1221         .start = dl_seq_start,
1222         .next  = dl_seq_next,
1223         .stop  = dl_seq_stop,
1224         .show  = dl_seq_show
1225 };
1226
1227 static int __net_init hashlimit_proc_net_init(struct net *net)
1228 {
1229         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1230
1231         hashlimit_net->ipt_hashlimit = proc_mkdir("ipt_hashlimit", net->proc_net);
1232         if (!hashlimit_net->ipt_hashlimit)
1233                 return -ENOMEM;
1234 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1235         hashlimit_net->ip6t_hashlimit = proc_mkdir("ip6t_hashlimit", net->proc_net);
1236         if (!hashlimit_net->ip6t_hashlimit) {
1237                 remove_proc_entry("ipt_hashlimit", net->proc_net);
1238                 return -ENOMEM;
1239         }
1240 #endif
1241         return 0;
1242 }
1243
1244 static void __net_exit hashlimit_proc_net_exit(struct net *net)
1245 {
1246         struct xt_hashlimit_htable *hinfo;
1247         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1248
1249         /* hashlimit_net_exit() is called before hashlimit_mt_destroy().
1250          * Make sure that the parent ipt_hashlimit and ip6t_hashlimit proc
1251          * entries is empty before trying to remove it.
1252          */
1253         mutex_lock(&hashlimit_mutex);
1254         hlist_for_each_entry(hinfo, &hashlimit_net->htables, node)
1255                 htable_remove_proc_entry(hinfo);
1256         hashlimit_net->ipt_hashlimit = NULL;
1257         hashlimit_net->ip6t_hashlimit = NULL;
1258         mutex_unlock(&hashlimit_mutex);
1259
1260         remove_proc_entry("ipt_hashlimit", net->proc_net);
1261 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1262         remove_proc_entry("ip6t_hashlimit", net->proc_net);
1263 #endif
1264 }
1265
1266 static int __net_init hashlimit_net_init(struct net *net)
1267 {
1268         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1269
1270         INIT_HLIST_HEAD(&hashlimit_net->htables);
1271         return hashlimit_proc_net_init(net);
1272 }
1273
1274 static void __net_exit hashlimit_net_exit(struct net *net)
1275 {
1276         hashlimit_proc_net_exit(net);
1277 }
1278
1279 static struct pernet_operations hashlimit_net_ops = {
1280         .init   = hashlimit_net_init,
1281         .exit   = hashlimit_net_exit,
1282         .id     = &hashlimit_net_id,
1283         .size   = sizeof(struct hashlimit_net),
1284 };
1285
1286 static int __init hashlimit_mt_init(void)
1287 {
1288         int err;
1289
1290         err = register_pernet_subsys(&hashlimit_net_ops);
1291         if (err < 0)
1292                 return err;
1293         err = xt_register_matches(hashlimit_mt_reg,
1294               ARRAY_SIZE(hashlimit_mt_reg));
1295         if (err < 0)
1296                 goto err1;
1297
1298         err = -ENOMEM;
1299         hashlimit_cachep = kmem_cache_create("xt_hashlimit",
1300                                             sizeof(struct dsthash_ent), 0, 0,
1301                                             NULL);
1302         if (!hashlimit_cachep) {
1303                 pr_warn("unable to create slab cache\n");
1304                 goto err2;
1305         }
1306         return 0;
1307
1308 err2:
1309         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
1310 err1:
1311         unregister_pernet_subsys(&hashlimit_net_ops);
1312         return err;
1313
1314 }
1315
1316 static void __exit hashlimit_mt_exit(void)
1317 {
1318         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
1319         unregister_pernet_subsys(&hashlimit_net_ops);
1320
1321         rcu_barrier();
1322         kmem_cache_destroy(hashlimit_cachep);
1323 }
1324
1325 module_init(hashlimit_mt_init);
1326 module_exit(hashlimit_mt_exit);