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 <uapi/linux/netfilter/xt_hashlimit.h>
  40
  41 #define XT_HASHLIMIT_ALL (XT_HASHLIMIT_HASH_DIP | XT_HASHLIMIT_HASH_DPT | \
  42                           XT_HASHLIMIT_HASH_SIP | XT_HASHLIMIT_HASH_SPT | \
  43                           XT_HASHLIMIT_INVERT | XT_HASHLIMIT_BYTES |\
  44                           XT_HASHLIMIT_RATE_MATCH)
  45
  46 MODULE_LICENSE("GPL");
  47 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  48 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
  49 MODULE_DESCRIPTION("Xtables: per hash-bucket rate-limit match");
  50 MODULE_ALIAS("ipt_hashlimit");
  51 MODULE_ALIAS("ip6t_hashlimit");
  52
  53 struct hashlimit_net {
  54         struct hlist_head       htables;
  55         struct proc_dir_entry   *ipt_hashlimit;
  56         struct proc_dir_entry   *ip6t_hashlimit;
  57 };
  58
  59 static unsigned int hashlimit_net_id;
  60 static inline struct hashlimit_net *hashlimit_pernet(struct net *net)
  61 {
  62         return net_generic(net, hashlimit_net_id);
  63 }
  64
  65 /* need to declare this at the top */
  66 static const struct seq_operations dl_seq_ops_v2;
  67 static const struct seq_operations dl_seq_ops_v1;
  68 static const struct seq_operations dl_seq_ops;
  69
  70 /* hash table crap */
  71 struct dsthash_dst {
  72         union {
  73                 struct {
  74                         __be32 src;
  75                         __be32 dst;
  76                 } ip;
  77 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
  78                 struct {
  79                         __be32 src[4];
  80                         __be32 dst[4];
  81                 } ip6;
  82 #endif
  83         };
  84         __be16 src_port;
  85         __be16 dst_port;
  86 };
  87
  88 struct dsthash_ent {
  89         /* static / read-only parts in the beginning */
  90         struct hlist_node node;
  91         struct dsthash_dst dst;
  92
  93         /* modified structure members in the end */
  94         spinlock_t lock;
  95         unsigned long expires;          /* precalculated expiry time */
  96         struct {
  97                 unsigned long prev;     /* last modification */
  98                 union {
  99                         struct {
 100                                 u_int64_t credit;
 101                                 u_int64_t credit_cap;
 102                                 u_int64_t cost;
 103                         };
 104                         struct {
 105                                 u_int32_t interval, prev_window;
 106                                 u_int64_t current_rate;
 107                                 u_int64_t rate;
 108                                 int64_t burst;
 109                         };
 110                 };
 111         } rateinfo;
 112         struct rcu_head rcu;
 113 };
 114
 115 struct xt_hashlimit_htable {
 116         struct hlist_node node;         /* global list of all htables */
 117         int use;
 118         u_int8_t family;
 119         bool rnd_initialized;
 120
 121         struct hashlimit_cfg3 cfg;      /* config */
 122
 123         /* used internally */
 124         spinlock_t lock;                /* lock for list_head */
 125         u_int32_t rnd;                  /* random seed for hash */
 126         unsigned int count;             /* number entries in table */
 127         struct delayed_work gc_work;
 128
 129         /* seq_file stuff */
 130         struct proc_dir_entry *pde;
 131         const char *name;
 132         struct net *net;
 133
 134         struct hlist_head hash[0];      /* hashtable itself */
 135 };
 136
 137 static int
 138 cfg_copy(struct hashlimit_cfg3 *to, const void *from, int revision)
 139 {
 140         if (revision == 1) {
 141                 struct hashlimit_cfg1 *cfg = (struct hashlimit_cfg1 *)from;
 142
 143                 to->mode = cfg->mode;
 144                 to->avg = cfg->avg;
 145                 to->burst = cfg->burst;
 146                 to->size = cfg->size;
 147                 to->max = cfg->max;
 148                 to->gc_interval = cfg->gc_interval;
 149                 to->expire = cfg->expire;
 150                 to->srcmask = cfg->srcmask;
 151                 to->dstmask = cfg->dstmask;
 152         } else if (revision == 2) {
 153                 struct hashlimit_cfg2 *cfg = (struct hashlimit_cfg2 *)from;
 154
 155                 to->mode = cfg->mode;
 156                 to->avg = cfg->avg;
 157                 to->burst = cfg->burst;
 158                 to->size = cfg->size;
 159                 to->max = cfg->max;
 160                 to->gc_interval = cfg->gc_interval;
 161                 to->expire = cfg->expire;
 162                 to->srcmask = cfg->srcmask;
 163                 to->dstmask = cfg->dstmask;
 164         } else if (revision == 3) {
 165                 memcpy(to, from, sizeof(struct hashlimit_cfg3));
 166         } else {
 167                 return -EINVAL;
 168         }
 169
 170         return 0;
 171 }
 172
 173 static DEFINE_MUTEX(hashlimit_mutex);   /* protects htables list */
 174 static struct kmem_cache *hashlimit_cachep __read_mostly;
 175
 176 static inline bool dst_cmp(const struct dsthash_ent *ent,
 177                            const struct dsthash_dst *b)
 178 {
 179         return !memcmp(&ent->dst, b, sizeof(ent->dst));
 180 }
 181
 182 static u_int32_t
 183 hash_dst(const struct xt_hashlimit_htable *ht, const struct dsthash_dst *dst)
 184 {
 185         u_int32_t hash = jhash2((const u32 *)dst,
 186                                 sizeof(*dst)/sizeof(u32),
 187                                 ht->rnd);
 188         /*
 189          * Instead of returning hash % ht->cfg.size (implying a divide)
 190          * we return the high 32 bits of the (hash * ht->cfg.size) that will
 191          * give results between [0 and cfg.size-1] and same hash distribution,
 192          * but using a multiply, less expensive than a divide
 193          */
 194         return reciprocal_scale(hash, ht->cfg.size);
 195 }
 196
 197 static struct dsthash_ent *
 198 dsthash_find(const struct xt_hashlimit_htable *ht,
 199              const struct dsthash_dst *dst)
 200 {
 201         struct dsthash_ent *ent;
 202         u_int32_t hash = hash_dst(ht, dst);
 203
 204         if (!hlist_empty(&ht->hash[hash])) {
 205                 hlist_for_each_entry_rcu(ent, &ht->hash[hash], node)
 206                         if (dst_cmp(ent, dst)) {
 207                                 spin_lock(&ent->lock);
 208                                 return ent;
 209                         }
 210         }
 211         return NULL;
 212 }
 213
 214 /* allocate dsthash_ent, initialize dst, put in htable and lock it */
 215 static struct dsthash_ent *
 216 dsthash_alloc_init(struct xt_hashlimit_htable *ht,
 217                    const struct dsthash_dst *dst, bool *race)
 218 {
 219         struct dsthash_ent *ent;
 220
 221         spin_lock(&ht->lock);
 222
 223         /* Two or more packets may race to create the same entry in the
 224          * hashtable, double check if this packet lost race.
 225          */
 226         ent = dsthash_find(ht, dst);
 227         if (ent != NULL) {
 228                 spin_unlock(&ht->lock);
 229                 *race = true;
 230                 return ent;
 231         }
 232
 233         /* initialize hash with random val at the time we allocate
 234          * the first hashtable entry */
 235         if (unlikely(!ht->rnd_initialized)) {
 236                 get_random_bytes(&ht->rnd, sizeof(ht->rnd));
 237                 ht->rnd_initialized = true;
 238         }
 239
 240         if (ht->cfg.max && ht->count >= ht->cfg.max) {
 241                 /* FIXME: do something. question is what.. */
 242                 net_err_ratelimited("max count of %u reached\n", ht->cfg.max);
 243                 ent = NULL;
 244         } else
 245                 ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
 246         if (ent) {
 247                 memcpy(&ent->dst, dst, sizeof(ent->dst));
 248                 spin_lock_init(&ent->lock);
 249
 250                 spin_lock(&ent->lock);
 251                 hlist_add_head_rcu(&ent->node, &ht->hash[hash_dst(ht, dst)]);
 252                 ht->count++;
 253         }
 254         spin_unlock(&ht->lock);
 255         return ent;
 256 }
 257
 258 static void dsthash_free_rcu(struct rcu_head *head)
 259 {
 260         struct dsthash_ent *ent = container_of(head, struct dsthash_ent, rcu);
 261
 262         kmem_cache_free(hashlimit_cachep, ent);
 263 }
 264
 265 static inline void
 266 dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent)
 267 {
 268         hlist_del_rcu(&ent->node);
 269         call_rcu(&ent->rcu, dsthash_free_rcu);
 270         ht->count--;
 271 }
 272 static void htable_gc(struct work_struct *work);
 273
 274 static int htable_create(struct net *net, struct hashlimit_cfg3 *cfg,
 275                          const char *name, u_int8_t family,
 276                          struct xt_hashlimit_htable **out_hinfo,
 277                          int revision)
 278 {
 279         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
 280         struct xt_hashlimit_htable *hinfo;
 281         const struct seq_operations *ops;
 282         unsigned int size, i;
 283         unsigned long nr_pages = totalram_pages();
 284         int ret;
 285
 286         if (cfg->size) {
 287                 size = cfg->size;
 288         } else {
 289                 size = (nr_pages << PAGE_SHIFT) / 16384 /
 290                        sizeof(struct hlist_head);
 291                 if (nr_pages > 1024 * 1024 * 1024 / PAGE_SIZE)
 292                         size = 8192;
 293                 if (size < 16)
 294                         size = 16;
 295         }
 296         /* FIXME: don't use vmalloc() here or anywhere else -HW */
 297         hinfo = vmalloc(struct_size(hinfo, hash, size));
 298         if (hinfo == NULL)
 299                 return -ENOMEM;
 300         *out_hinfo = hinfo;
 301
 302         /* copy match config into hashtable config */
 303         ret = cfg_copy(&hinfo->cfg, (void *)cfg, 3);
 304         if (ret) {
 305                 vfree(hinfo);
 306                 return ret;
 307         }
 308
 309         hinfo->cfg.size = size;
 310         if (hinfo->cfg.max == 0)
 311                 hinfo->cfg.max = 8 * hinfo->cfg.size;
 312         else if (hinfo->cfg.max < hinfo->cfg.size)
 313                 hinfo->cfg.max = hinfo->cfg.size;
 314
 315         for (i = 0; i < hinfo->cfg.size; i++)
 316                 INIT_HLIST_HEAD(&hinfo->hash[i]);
 317
 318         hinfo->use = 1;
 319         hinfo->count = 0;
 320         hinfo->family = family;
 321         hinfo->rnd_initialized = false;
 322         hinfo->name = kstrdup(name, GFP_KERNEL);
 323         if (!hinfo->name) {
 324                 vfree(hinfo);
 325                 return -ENOMEM;
 326         }
 327         spin_lock_init(&hinfo->lock);
 328
 329         switch (revision) {
 330         case 1:
 331                 ops = &dl_seq_ops_v1;
 332                 break;
 333         case 2:
 334                 ops = &dl_seq_ops_v2;
 335                 break;
 336         default:
 337                 ops = &dl_seq_ops;
 338         }
 339
 340         hinfo->pde = proc_create_seq_data(name, 0,
 341                 (family == NFPROTO_IPV4) ?
 342                 hashlimit_net->ipt_hashlimit : hashlimit_net->ip6t_hashlimit,
 343                 ops, hinfo);
 344         if (hinfo->pde == NULL) {
 345                 kfree(hinfo->name);
 346                 vfree(hinfo);
 347                 return -ENOMEM;
 348         }
 349         hinfo->net = net;
 350
 351         INIT_DEFERRABLE_WORK(&hinfo->gc_work, htable_gc);
 352         queue_delayed_work(system_power_efficient_wq, &hinfo->gc_work,
 353                            msecs_to_jiffies(hinfo->cfg.gc_interval));
 354
 355         hlist_add_head(&hinfo->node, &hashlimit_net->htables);
 356
 357         return 0;
 358 }
 359
 360 static bool select_all(const struct xt_hashlimit_htable *ht,
 361                        const struct dsthash_ent *he)
 362 {
 363         return true;
 364 }
 365
 366 static bool select_gc(const struct xt_hashlimit_htable *ht,
 367                       const struct dsthash_ent *he)
 368 {
 369         return time_after_eq(jiffies, he->expires);
 370 }
 371
 372 static void htable_selective_cleanup(struct xt_hashlimit_htable *ht,
 373                         bool (*select)(const struct xt_hashlimit_htable *ht,
 374                                       const struct dsthash_ent *he))
 375 {
 376         unsigned int i;
 377
 378         for (i = 0; i < ht->cfg.size; i++) {
 379                 struct dsthash_ent *dh;
 380                 struct hlist_node *n;
 381
 382                 spin_lock_bh(&ht->lock);
 383                 hlist_for_each_entry_safe(dh, n, &ht->hash[i], node) {
 384                         if ((*select)(ht, dh))
 385                                 dsthash_free(ht, dh);
 386                 }
 387                 spin_unlock_bh(&ht->lock);
 388                 cond_resched();
 389         }
 390 }
 391
 392 static void htable_gc(struct work_struct *work)
 393 {
 394         struct xt_hashlimit_htable *ht;
 395
 396         ht = container_of(work, struct xt_hashlimit_htable, gc_work.work);
 397
 398         htable_selective_cleanup(ht, select_gc);
 399
 400         queue_delayed_work(system_power_efficient_wq,
 401                            &ht->gc_work, msecs_to_jiffies(ht->cfg.gc_interval));
 402 }
 403
 404 static void htable_remove_proc_entry(struct xt_hashlimit_htable *hinfo)
 405 {
 406         struct hashlimit_net *hashlimit_net = hashlimit_pernet(hinfo->net);
 407         struct proc_dir_entry *parent;
 408
 409         if (hinfo->family == NFPROTO_IPV4)
 410                 parent = hashlimit_net->ipt_hashlimit;
 411         else
 412                 parent = hashlimit_net->ip6t_hashlimit;
 413
 414         if (parent != NULL)
 415                 remove_proc_entry(hinfo->name, parent);
 416 }
 417
 418 static void htable_destroy(struct xt_hashlimit_htable *hinfo)
 419 {
 420         cancel_delayed_work_sync(&hinfo->gc_work);
 421         htable_remove_proc_entry(hinfo);
 422         htable_selective_cleanup(hinfo, select_all);
 423         kfree(hinfo->name);
 424         vfree(hinfo);
 425 }
 426
 427 static struct xt_hashlimit_htable *htable_find_get(struct net *net,
 428                                                    const char *name,
 429                                                    u_int8_t family)
 430 {
 431         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
 432         struct xt_hashlimit_htable *hinfo;
 433
 434         hlist_for_each_entry(hinfo, &hashlimit_net->htables, node) {
 435                 if (!strcmp(name, hinfo->name) &&
 436                     hinfo->family == family) {
 437                         hinfo->use++;
 438                         return hinfo;
 439                 }
 440         }
 441         return NULL;
 442 }
 443
 444 static void htable_put(struct xt_hashlimit_htable *hinfo)
 445 {
 446         mutex_lock(&hashlimit_mutex);
 447         if (--hinfo->use == 0) {
 448                 hlist_del(&hinfo->node);
 449                 htable_destroy(hinfo);
 450         }
 451         mutex_unlock(&hashlimit_mutex);
 452 }
 453
 454 /* The algorithm used is the Simple Token Bucket Filter (TBF)
 455  * see net/sched/sch_tbf.c in the linux source tree
 456  */
 457
 458 /* Rusty: This is my (non-mathematically-inclined) understanding of
 459    this algorithm.  The `average rate' in jiffies becomes your initial
 460    amount of credit `credit' and the most credit you can ever have
 461    `credit_cap'.  The `peak rate' becomes the cost of passing the
 462    test, `cost'.
 463
 464    `prev' tracks the last packet hit: you gain one credit per jiffy.
 465    If you get credit balance more than this, the extra credit is
 466    discarded.  Every time the match passes, you lose `cost' credits;
 467    if you don't have that many, the test fails.
 468
 469    See Alexey's formal explanation in net/sched/sch_tbf.c.
 470
 471    To get the maximum range, we multiply by this factor (ie. you get N
 472    credits per jiffy).  We want to allow a rate as low as 1 per day
 473    (slowest userspace tool allows), which means
 474    CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
 475 */
 476 #define MAX_CPJ_v1 (0xFFFFFFFF / (HZ*60*60*24))
 477 #define MAX_CPJ (0xFFFFFFFFFFFFFFFFULL / (HZ*60*60*24))
 478
 479 /* Repeated shift and or gives us all 1s, final shift and add 1 gives
 480  * us the power of 2 below the theoretical max, so GCC simply does a
 481  * shift. */
 482 #define _POW2_BELOW2(x) ((x)|((x)>>1))
 483 #define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
 484 #define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
 485 #define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
 486 #define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
 487 #define _POW2_BELOW64(x) (_POW2_BELOW32(x)|_POW2_BELOW32((x)>>32))
 488 #define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
 489 #define POW2_BELOW64(x) ((_POW2_BELOW64(x)>>1) + 1)
 490
 491 #define CREDITS_PER_JIFFY POW2_BELOW64(MAX_CPJ)
 492 #define CREDITS_PER_JIFFY_v1 POW2_BELOW32(MAX_CPJ_v1)
 493
 494 /* in byte mode, the lowest possible rate is one packet/second.
 495  * credit_cap is used as a counter that tells us how many times we can
 496  * refill the "credits available" counter when it becomes empty.
 497  */
 498 #define MAX_CPJ_BYTES (0xFFFFFFFF / HZ)
 499 #define CREDITS_PER_JIFFY_BYTES POW2_BELOW32(MAX_CPJ_BYTES)
 500
 501 static u32 xt_hashlimit_len_to_chunks(u32 len)
 502 {
 503         return (len >> XT_HASHLIMIT_BYTE_SHIFT) + 1;
 504 }
 505
 506 /* Precision saver. */
 507 static u64 user2credits(u64 user, int revision)
 508 {
 509         u64 scale = (revision == 1) ?
 510                 XT_HASHLIMIT_SCALE : XT_HASHLIMIT_SCALE_v2;
 511         u64 cpj = (revision == 1) ?
 512                 CREDITS_PER_JIFFY_v1 : CREDITS_PER_JIFFY;
 513
 514         /* Avoid overflow: divide the constant operands first */
 515         if (scale >= HZ * cpj)
 516                 return div64_u64(user, div64_u64(scale, HZ * cpj));
 517
 518         return user * div64_u64(HZ * cpj, scale);
 519 }
 520
 521 static u32 user2credits_byte(u32 user)
 522 {
 523         u64 us = user;
 524         us *= HZ * CREDITS_PER_JIFFY_BYTES;
 525         return (u32) (us >> 32);
 526 }
 527
 528 static u64 user2rate(u64 user)
 529 {
 530         if (user != 0) {
 531                 return div64_u64(XT_HASHLIMIT_SCALE_v2, user);
 532         } else {
 533                 pr_info_ratelimited("invalid rate from userspace: %llu\n",
 534                                     user);
 535                 return 0;
 536         }
 537 }
 538
 539 static u64 user2rate_bytes(u32 user)
 540 {
 541         u64 r;
 542
 543         r = user ? U32_MAX / user : U32_MAX;
 544         return (r - 1) << XT_HASHLIMIT_BYTE_SHIFT;
 545 }
 546
 547 static void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now,
 548                             u32 mode, int revision)
 549 {
 550         unsigned long delta = now - dh->rateinfo.prev;
 551         u64 cap, cpj;
 552
 553         if (delta == 0)
 554                 return;
 555
 556         if (revision >= 3 && mode & XT_HASHLIMIT_RATE_MATCH) {
 557                 u64 interval = dh->rateinfo.interval * HZ;
 558
 559                 if (delta < interval)
 560                         return;
 561
 562                 dh->rateinfo.prev = now;
 563                 dh->rateinfo.prev_window =
 564                         ((dh->rateinfo.current_rate * interval) >
 565                          (delta * dh->rateinfo.rate));
 566                 dh->rateinfo.current_rate = 0;
 567
 568                 return;
 569         }
 570
 571         dh->rateinfo.prev = now;
 572
 573         if (mode & XT_HASHLIMIT_BYTES) {
 574                 u64 tmp = dh->rateinfo.credit;
 575                 dh->rateinfo.credit += CREDITS_PER_JIFFY_BYTES * delta;
 576                 cap = CREDITS_PER_JIFFY_BYTES * HZ;
 577                 if (tmp >= dh->rateinfo.credit) {/* overflow */
 578                         dh->rateinfo.credit = cap;
 579                         return;
 580                 }
 581         } else {
 582                 cpj = (revision == 1) ?
 583                         CREDITS_PER_JIFFY_v1 : CREDITS_PER_JIFFY;
 584                 dh->rateinfo.credit += delta * cpj;
 585                 cap = dh->rateinfo.credit_cap;
 586         }
 587         if (dh->rateinfo.credit > cap)
 588                 dh->rateinfo.credit = cap;
 589 }
 590
 591 static void rateinfo_init(struct dsthash_ent *dh,
 592                           struct xt_hashlimit_htable *hinfo, int revision)
 593 {
 594         dh->rateinfo.prev = jiffies;
 595         if (revision >= 3 && hinfo->cfg.mode & XT_HASHLIMIT_RATE_MATCH) {
 596                 dh->rateinfo.prev_window = 0;
 597                 dh->rateinfo.current_rate = 0;
 598                 if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) {
 599                         dh->rateinfo.rate =
 600                                 user2rate_bytes((u32)hinfo->cfg.avg);
 601                         if (hinfo->cfg.burst)
 602                                 dh->rateinfo.burst =
 603                                         hinfo->cfg.burst * dh->rateinfo.rate;
 604                         else
 605                                 dh->rateinfo.burst = dh->rateinfo.rate;
 606                 } else {
 607                         dh->rateinfo.rate = user2rate(hinfo->cfg.avg);
 608                         dh->rateinfo.burst =
 609                                 hinfo->cfg.burst + dh->rateinfo.rate;
 610                 }
 611                 dh->rateinfo.interval = hinfo->cfg.interval;
 612         } else if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) {
 613                 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
 614                 dh->rateinfo.cost = user2credits_byte(hinfo->cfg.avg);
 615                 dh->rateinfo.credit_cap = hinfo->cfg.burst;
 616         } else {
 617                 dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
 618                                                    hinfo->cfg.burst, revision);
 619                 dh->rateinfo.cost = user2credits(hinfo->cfg.avg, revision);
 620                 dh->rateinfo.credit_cap = dh->rateinfo.credit;
 621         }
 622 }
 623
 624 static inline __be32 maskl(__be32 a, unsigned int l)
 625 {
 626         return l ? htonl(ntohl(a) & ~0 << (32 - l)) : 0;
 627 }
 628
 629 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 630 static void hashlimit_ipv6_mask(__be32 *i, unsigned int p)
 631 {
 632         switch (p) {
 633         case 0 ... 31:
 634                 i[0] = maskl(i[0], p);
 635                 i[1] = i[2] = i[3] = 0;
 636                 break;
 637         case 32 ... 63:
 638                 i[1] = maskl(i[1], p - 32);
 639                 i[2] = i[3] = 0;
 640                 break;
 641         case 64 ... 95:
 642                 i[2] = maskl(i[2], p - 64);
 643                 i[3] = 0;
 644                 break;
 645         case 96 ... 127:
 646                 i[3] = maskl(i[3], p - 96);
 647                 break;
 648         case 128:
 649                 break;
 650         }
 651 }
 652 #endif
 653
 654 static int
 655 hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
 656                    struct dsthash_dst *dst,
 657                    const struct sk_buff *skb, unsigned int protoff)
 658 {
 659         __be16 _ports[2], *ports;
 660         u8 nexthdr;
 661         int poff;
 662
 663         memset(dst, 0, sizeof(*dst));
 664
 665         switch (hinfo->family) {
 666         case NFPROTO_IPV4:
 667                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
 668                         dst->ip.dst = maskl(ip_hdr(skb)->daddr,
 669                                       hinfo->cfg.dstmask);
 670                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
 671                         dst->ip.src = maskl(ip_hdr(skb)->saddr,
 672                                       hinfo->cfg.srcmask);
 673
 674                 if (!(hinfo->cfg.mode &
 675                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
 676                         return 0;
 677                 nexthdr = ip_hdr(skb)->protocol;
 678                 break;
 679 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 680         case NFPROTO_IPV6:
 681         {
 682                 __be16 frag_off;
 683
 684                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) {
 685                         memcpy(&dst->ip6.dst, &ipv6_hdr(skb)->daddr,
 686                                sizeof(dst->ip6.dst));
 687                         hashlimit_ipv6_mask(dst->ip6.dst, hinfo->cfg.dstmask);
 688                 }
 689                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) {
 690                         memcpy(&dst->ip6.src, &ipv6_hdr(skb)->saddr,
 691                                sizeof(dst->ip6.src));
 692                         hashlimit_ipv6_mask(dst->ip6.src, hinfo->cfg.srcmask);
 693                 }
 694
 695                 if (!(hinfo->cfg.mode &
 696                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
 697                         return 0;
 698                 nexthdr = ipv6_hdr(skb)->nexthdr;
 699                 protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, &frag_off);
 700                 if ((int)protoff < 0)
 701                         return -1;
 702                 break;
 703         }
 704 #endif
 705         default:
 706                 BUG();
 707                 return 0;
 708         }
 709
 710         poff = proto_ports_offset(nexthdr);
 711         if (poff >= 0) {
 712                 ports = skb_header_pointer(skb, protoff + poff, sizeof(_ports),
 713                                            &_ports);
 714         } else {
 715                 _ports[0] = _ports[1] = 0;
 716                 ports = _ports;
 717         }
 718         if (!ports)
 719                 return -1;
 720         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT)
 721                 dst->src_port = ports[0];
 722         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT)
 723                 dst->dst_port = ports[1];
 724         return 0;
 725 }
 726
 727 static u32 hashlimit_byte_cost(unsigned int len, struct dsthash_ent *dh)
 728 {
 729         u64 tmp = xt_hashlimit_len_to_chunks(len);
 730         tmp = tmp * dh->rateinfo.cost;
 731
 732         if (unlikely(tmp > CREDITS_PER_JIFFY_BYTES * HZ))
 733                 tmp = CREDITS_PER_JIFFY_BYTES * HZ;
 734
 735         if (dh->rateinfo.credit < tmp && dh->rateinfo.credit_cap) {
 736                 dh->rateinfo.credit_cap--;
 737                 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
 738         }
 739         return (u32) tmp;
 740 }
 741
 742 static bool
 743 hashlimit_mt_common(const struct sk_buff *skb, struct xt_action_param *par,
 744                     struct xt_hashlimit_htable *hinfo,
 745                     const struct hashlimit_cfg3 *cfg, int revision)
 746 {
 747         unsigned long now = jiffies;
 748         struct dsthash_ent *dh;
 749         struct dsthash_dst dst;
 750         bool race = false;
 751         u64 cost;
 752
 753         if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0)
 754                 goto hotdrop;
 755
 756         local_bh_disable();
 757         dh = dsthash_find(hinfo, &dst);
 758         if (dh == NULL) {
 759                 dh = dsthash_alloc_init(hinfo, &dst, &race);
 760                 if (dh == NULL) {
 761                         local_bh_enable();
 762                         goto hotdrop;
 763                 } else if (race) {
 764                         /* Already got an entry, update expiration timeout */
 765                         dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
 766                         rateinfo_recalc(dh, now, hinfo->cfg.mode, revision);
 767                 } else {
 768                         dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
 769                         rateinfo_init(dh, hinfo, revision);
 770                 }
 771         } else {
 772                 /* update expiration timeout */
 773                 dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
 774                 rateinfo_recalc(dh, now, hinfo->cfg.mode, revision);
 775         }
 776
 777         if (cfg->mode & XT_HASHLIMIT_RATE_MATCH) {
 778                 cost = (cfg->mode & XT_HASHLIMIT_BYTES) ? skb->len : 1;
 779                 dh->rateinfo.current_rate += cost;
 780
 781                 if (!dh->rateinfo.prev_window &&
 782                     (dh->rateinfo.current_rate <= dh->rateinfo.burst)) {
 783                         spin_unlock(&dh->lock);
 784                         local_bh_enable();
 785                         return !(cfg->mode & XT_HASHLIMIT_INVERT);
 786                 } else {
 787                         goto overlimit;
 788                 }
 789         }
 790
 791         if (cfg->mode & XT_HASHLIMIT_BYTES)
 792                 cost = hashlimit_byte_cost(skb->len, dh);
 793         else
 794                 cost = dh->rateinfo.cost;
 795
 796         if (dh->rateinfo.credit >= cost) {
 797                 /* below the limit */
 798                 dh->rateinfo.credit -= cost;
 799                 spin_unlock(&dh->lock);
 800                 local_bh_enable();
 801                 return !(cfg->mode & XT_HASHLIMIT_INVERT);
 802         }
 803
 804 overlimit:
 805         spin_unlock(&dh->lock);
 806         local_bh_enable();
 807         /* default match is underlimit - so over the limit, we need to invert */
 808         return cfg->mode & XT_HASHLIMIT_INVERT;
 809
 810  hotdrop:
 811         par->hotdrop = true;
 812         return false;
 813 }
 814
 815 static bool
 816 hashlimit_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
 817 {
 818         const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
 819         struct xt_hashlimit_htable *hinfo = info->hinfo;
 820         struct hashlimit_cfg3 cfg = {};
 821         int ret;
 822
 823         ret = cfg_copy(&cfg, (void *)&info->cfg, 1);
 824         if (ret)
 825                 return ret;
 826
 827         return hashlimit_mt_common(skb, par, hinfo, &cfg, 1);
 828 }
 829
 830 static bool
 831 hashlimit_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
 832 {
 833         const struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
 834         struct xt_hashlimit_htable *hinfo = info->hinfo;
 835         struct hashlimit_cfg3 cfg = {};
 836         int ret;
 837
 838         ret = cfg_copy(&cfg, (void *)&info->cfg, 2);
 839         if (ret)
 840                 return ret;
 841
 842         return hashlimit_mt_common(skb, par, hinfo, &cfg, 2);
 843 }
 844
 845 static bool
 846 hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par)
 847 {
 848         const struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
 849         struct xt_hashlimit_htable *hinfo = info->hinfo;
 850
 851         return hashlimit_mt_common(skb, par, hinfo, &info->cfg, 3);
 852 }
 853
 854 static int hashlimit_mt_check_common(const struct xt_mtchk_param *par,
 855                                      struct xt_hashlimit_htable **hinfo,
 856                                      struct hashlimit_cfg3 *cfg,
 857                                      const char *name, int revision)
 858 {
 859         struct net *net = par->net;
 860         int ret;
 861
 862         if (cfg->gc_interval == 0 || cfg->expire == 0)
 863                 return -EINVAL;
 864         if (par->family == NFPROTO_IPV4) {
 865                 if (cfg->srcmask > 32 || cfg->dstmask > 32)
 866                         return -EINVAL;
 867         } else {
 868                 if (cfg->srcmask > 128 || cfg->dstmask > 128)
 869                         return -EINVAL;
 870         }
 871
 872         if (cfg->mode & ~XT_HASHLIMIT_ALL) {
 873                 pr_info_ratelimited("Unknown mode mask %X, kernel too old?\n",
 874                                     cfg->mode);
 875                 return -EINVAL;
 876         }
 877
 878         /* Check for overflow. */
 879         if (revision >= 3 && cfg->mode & XT_HASHLIMIT_RATE_MATCH) {
 880                 if (cfg->avg == 0 || cfg->avg > U32_MAX) {
 881                         pr_info_ratelimited("invalid rate\n");
 882                         return -ERANGE;
 883                 }
 884
 885                 if (cfg->interval == 0) {
 886                         pr_info_ratelimited("invalid interval\n");
 887                         return -EINVAL;
 888                 }
 889         } else if (cfg->mode & XT_HASHLIMIT_BYTES) {
 890                 if (user2credits_byte(cfg->avg) == 0) {
 891                         pr_info_ratelimited("overflow, rate too high: %llu\n",
 892                                             cfg->avg);
 893                         return -EINVAL;
 894                 }
 895         } else if (cfg->burst == 0 ||
 896                    user2credits(cfg->avg * cfg->burst, revision) <
 897                    user2credits(cfg->avg, revision)) {
 898                 pr_info_ratelimited("overflow, try lower: %llu/%llu\n",
 899                                     cfg->avg, cfg->burst);
 900                 return -ERANGE;
 901         }
 902
 903         mutex_lock(&hashlimit_mutex);
 904         *hinfo = htable_find_get(net, name, par->family);
 905         if (*hinfo == NULL) {
 906                 ret = htable_create(net, cfg, name, par->family,
 907                                     hinfo, revision);
 908                 if (ret < 0) {
 909                         mutex_unlock(&hashlimit_mutex);
 910                         return ret;
 911                 }
 912         }
 913         mutex_unlock(&hashlimit_mutex);
 914
 915         return 0;
 916 }
 917
 918 static int hashlimit_mt_check_v1(const struct xt_mtchk_param *par)
 919 {
 920         struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
 921         struct hashlimit_cfg3 cfg = {};
 922         int ret;
 923
 924         ret = xt_check_proc_name(info->name, sizeof(info->name));
 925         if (ret)
 926                 return ret;
 927
 928         ret = cfg_copy(&cfg, (void *)&info->cfg, 1);
 929         if (ret)
 930                 return ret;
 931
 932         return hashlimit_mt_check_common(par, &info->hinfo,
 933                                          &cfg, info->name, 1);
 934 }
 935
 936 static int hashlimit_mt_check_v2(const struct xt_mtchk_param *par)
 937 {
 938         struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
 939         struct hashlimit_cfg3 cfg = {};
 940         int ret;
 941
 942         ret = xt_check_proc_name(info->name, sizeof(info->name));
 943         if (ret)
 944                 return ret;
 945
 946         ret = cfg_copy(&cfg, (void *)&info->cfg, 2);
 947         if (ret)
 948                 return ret;
 949
 950         return hashlimit_mt_check_common(par, &info->hinfo,
 951                                          &cfg, info->name, 2);
 952 }
 953
 954 static int hashlimit_mt_check(const struct xt_mtchk_param *par)
 955 {
 956         struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
 957         int ret;
 958
 959         ret = xt_check_proc_name(info->name, sizeof(info->name));
 960         if (ret)
 961                 return ret;
 962
 963         return hashlimit_mt_check_common(par, &info->hinfo, &info->cfg,
 964                                          info->name, 3);
 965 }
 966
 967 static void hashlimit_mt_destroy_v2(const struct xt_mtdtor_param *par)
 968 {
 969         const struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
 970
 971         htable_put(info->hinfo);
 972 }
 973
 974 static void hashlimit_mt_destroy_v1(const struct xt_mtdtor_param *par)
 975 {
 976         const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
 977
 978         htable_put(info->hinfo);
 979 }
 980
 981 static void hashlimit_mt_destroy(const struct xt_mtdtor_param *par)
 982 {
 983         const struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
 984
 985         htable_put(info->hinfo);
 986 }
 987
 988 static struct xt_match hashlimit_mt_reg[] __read_mostly = {
 989         {
 990                 .name           = "hashlimit",
 991                 .revision       = 1,
 992                 .family         = NFPROTO_IPV4,
 993                 .match          = hashlimit_mt_v1,
 994                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
 995                 .usersize       = offsetof(struct xt_hashlimit_mtinfo1, hinfo),
 996                 .checkentry     = hashlimit_mt_check_v1,
 997                 .destroy        = hashlimit_mt_destroy_v1,
 998                 .me             = THIS_MODULE,
 999         },
1000         {
1001                 .name           = "hashlimit",
1002                 .revision       = 2,
1003                 .family         = NFPROTO_IPV4,
1004                 .match          = hashlimit_mt_v2,
1005                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo2),
1006                 .usersize       = offsetof(struct xt_hashlimit_mtinfo2, hinfo),
1007                 .checkentry     = hashlimit_mt_check_v2,
1008                 .destroy        = hashlimit_mt_destroy_v2,
1009                 .me             = THIS_MODULE,
1010         },
1011         {
1012                 .name           = "hashlimit",
1013                 .revision       = 3,
1014                 .family         = NFPROTO_IPV4,
1015                 .match          = hashlimit_mt,
1016                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo3),
1017                 .usersize       = offsetof(struct xt_hashlimit_mtinfo3, hinfo),
1018                 .checkentry     = hashlimit_mt_check,
1019                 .destroy        = hashlimit_mt_destroy,
1020                 .me             = THIS_MODULE,
1021         },
1022 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1023         {
1024                 .name           = "hashlimit",
1025                 .revision       = 1,
1026                 .family         = NFPROTO_IPV6,
1027                 .match          = hashlimit_mt_v1,
1028                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
1029                 .usersize       = offsetof(struct xt_hashlimit_mtinfo1, hinfo),
1030                 .checkentry     = hashlimit_mt_check_v1,
1031                 .destroy        = hashlimit_mt_destroy_v1,
1032                 .me             = THIS_MODULE,
1033         },
1034         {
1035                 .name           = "hashlimit",
1036                 .revision       = 2,
1037                 .family         = NFPROTO_IPV6,
1038                 .match          = hashlimit_mt_v2,
1039                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo2),
1040                 .usersize       = offsetof(struct xt_hashlimit_mtinfo2, hinfo),
1041                 .checkentry     = hashlimit_mt_check_v2,
1042                 .destroy        = hashlimit_mt_destroy_v2,
1043                 .me             = THIS_MODULE,
1044         },
1045         {
1046                 .name           = "hashlimit",
1047                 .revision       = 3,
1048                 .family         = NFPROTO_IPV6,
1049                 .match          = hashlimit_mt,
1050                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo3),
1051                 .usersize       = offsetof(struct xt_hashlimit_mtinfo3, hinfo),
1052                 .checkentry     = hashlimit_mt_check,
1053                 .destroy        = hashlimit_mt_destroy,
1054                 .me             = THIS_MODULE,
1055         },
1056 #endif
1057 };
1058
1059 /* PROC stuff */
1060 static void *dl_seq_start(struct seq_file *s, loff_t *pos)
1061         __acquires(htable->lock)
1062 {
1063         struct xt_hashlimit_htable *htable = PDE_DATA(file_inode(s->file));
1064         unsigned int *bucket;
1065
1066         spin_lock_bh(&htable->lock);
1067         if (*pos >= htable->cfg.size)
1068                 return NULL;
1069
1070         bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
1071         if (!bucket)
1072                 return ERR_PTR(-ENOMEM);
1073
1074         *bucket = *pos;
1075         return bucket;
1076 }
1077
1078 static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
1079 {
1080         struct xt_hashlimit_htable *htable = PDE_DATA(file_inode(s->file));
1081         unsigned int *bucket = v;
1082
1083         *pos = ++(*bucket);
1084         if (*pos >= htable->cfg.size) {
1085                 kfree(v);
1086                 return NULL;
1087         }
1088         return bucket;
1089 }
1090
1091 static void dl_seq_stop(struct seq_file *s, void *v)
1092         __releases(htable->lock)
1093 {
1094         struct xt_hashlimit_htable *htable = PDE_DATA(file_inode(s->file));
1095         unsigned int *bucket = v;
1096
1097         if (!IS_ERR(bucket))
1098                 kfree(bucket);
1099         spin_unlock_bh(&htable->lock);
1100 }
1101
1102 static void dl_seq_print(struct dsthash_ent *ent, u_int8_t family,
1103                          struct seq_file *s)
1104 {
1105         switch (family) {
1106         case NFPROTO_IPV4:
1107                 seq_printf(s, "%ld %pI4:%u->%pI4:%u %llu %llu %llu\n",
1108                            (long)(ent->expires - jiffies)/HZ,
1109                            &ent->dst.ip.src,
1110                            ntohs(ent->dst.src_port),
1111                            &ent->dst.ip.dst,
1112                            ntohs(ent->dst.dst_port),
1113                            ent->rateinfo.credit, ent->rateinfo.credit_cap,
1114                            ent->rateinfo.cost);
1115                 break;
1116 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1117         case NFPROTO_IPV6:
1118                 seq_printf(s, "%ld %pI6:%u->%pI6:%u %llu %llu %llu\n",
1119                            (long)(ent->expires - jiffies)/HZ,
1120                            &ent->dst.ip6.src,
1121                            ntohs(ent->dst.src_port),
1122                            &ent->dst.ip6.dst,
1123                            ntohs(ent->dst.dst_port),
1124                            ent->rateinfo.credit, ent->rateinfo.credit_cap,
1125                            ent->rateinfo.cost);
1126                 break;
1127 #endif
1128         default:
1129                 BUG();
1130         }
1131 }
1132
1133 static int dl_seq_real_show_v2(struct dsthash_ent *ent, u_int8_t family,
1134                                struct seq_file *s)
1135 {
1136         struct xt_hashlimit_htable *ht = PDE_DATA(file_inode(s->file));
1137
1138         spin_lock(&ent->lock);
1139         /* recalculate to show accurate numbers */
1140         rateinfo_recalc(ent, jiffies, ht->cfg.mode, 2);
1141
1142         dl_seq_print(ent, family, s);
1143
1144         spin_unlock(&ent->lock);
1145         return seq_has_overflowed(s);
1146 }
1147
1148 static int dl_seq_real_show_v1(struct dsthash_ent *ent, u_int8_t family,
1149                                struct seq_file *s)
1150 {
1151         struct xt_hashlimit_htable *ht = PDE_DATA(file_inode(s->file));
1152
1153         spin_lock(&ent->lock);
1154         /* recalculate to show accurate numbers */
1155         rateinfo_recalc(ent, jiffies, ht->cfg.mode, 1);
1156
1157         dl_seq_print(ent, family, s);
1158
1159         spin_unlock(&ent->lock);
1160         return seq_has_overflowed(s);
1161 }
1162
1163 static int dl_seq_real_show(struct dsthash_ent *ent, u_int8_t family,
1164                             struct seq_file *s)
1165 {
1166         struct xt_hashlimit_htable *ht = PDE_DATA(file_inode(s->file));
1167
1168         spin_lock(&ent->lock);
1169         /* recalculate to show accurate numbers */
1170         rateinfo_recalc(ent, jiffies, ht->cfg.mode, 3);
1171
1172         dl_seq_print(ent, family, s);
1173
1174         spin_unlock(&ent->lock);
1175         return seq_has_overflowed(s);
1176 }
1177
1178 static int dl_seq_show_v2(struct seq_file *s, void *v)
1179 {
1180         struct xt_hashlimit_htable *htable = PDE_DATA(file_inode(s->file));
1181         unsigned int *bucket = (unsigned int *)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_v2(ent, htable->family, s))
1187                                 return -1;
1188         }
1189         return 0;
1190 }
1191
1192 static int dl_seq_show_v1(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_v1(ent, htable->family, s))
1201                                 return -1;
1202         }
1203         return 0;
1204 }
1205
1206 static int dl_seq_show(struct seq_file *s, void *v)
1207 {
1208         struct xt_hashlimit_htable *htable = PDE_DATA(file_inode(s->file));
1209         unsigned int *bucket = v;
1210         struct dsthash_ent *ent;
1211
1212         if (!hlist_empty(&htable->hash[*bucket])) {
1213                 hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1214                         if (dl_seq_real_show(ent, htable->family, s))
1215                                 return -1;
1216         }
1217         return 0;
1218 }
1219
1220 static const struct seq_operations dl_seq_ops_v1 = {
1221         .start = dl_seq_start,
1222         .next  = dl_seq_next,
1223         .stop  = dl_seq_stop,
1224         .show  = dl_seq_show_v1
1225 };
1226
1227 static const struct seq_operations dl_seq_ops_v2 = {
1228         .start = dl_seq_start,
1229         .next  = dl_seq_next,
1230         .stop  = dl_seq_stop,
1231         .show  = dl_seq_show_v2
1232 };
1233
1234 static const struct seq_operations dl_seq_ops = {
1235         .start = dl_seq_start,
1236         .next  = dl_seq_next,
1237         .stop  = dl_seq_stop,
1238         .show  = dl_seq_show
1239 };
1240
1241 static int __net_init hashlimit_proc_net_init(struct net *net)
1242 {
1243         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1244
1245         hashlimit_net->ipt_hashlimit = proc_mkdir("ipt_hashlimit", net->proc_net);
1246         if (!hashlimit_net->ipt_hashlimit)
1247                 return -ENOMEM;
1248 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1249         hashlimit_net->ip6t_hashlimit = proc_mkdir("ip6t_hashlimit", net->proc_net);
1250         if (!hashlimit_net->ip6t_hashlimit) {
1251                 remove_proc_entry("ipt_hashlimit", net->proc_net);
1252                 return -ENOMEM;
1253         }
1254 #endif
1255         return 0;
1256 }
1257
1258 static void __net_exit hashlimit_proc_net_exit(struct net *net)
1259 {
1260         struct xt_hashlimit_htable *hinfo;
1261         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1262
1263         /* hashlimit_net_exit() is called before hashlimit_mt_destroy().
1264          * Make sure that the parent ipt_hashlimit and ip6t_hashlimit proc
1265          * entries is empty before trying to remove it.
1266          */
1267         mutex_lock(&hashlimit_mutex);
1268         hlist_for_each_entry(hinfo, &hashlimit_net->htables, node)
1269                 htable_remove_proc_entry(hinfo);
1270         hashlimit_net->ipt_hashlimit = NULL;
1271         hashlimit_net->ip6t_hashlimit = NULL;
1272         mutex_unlock(&hashlimit_mutex);
1273
1274         remove_proc_entry("ipt_hashlimit", net->proc_net);
1275 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1276         remove_proc_entry("ip6t_hashlimit", net->proc_net);
1277 #endif
1278 }
1279
1280 static int __net_init hashlimit_net_init(struct net *net)
1281 {
1282         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1283
1284         INIT_HLIST_HEAD(&hashlimit_net->htables);
1285         return hashlimit_proc_net_init(net);
1286 }
1287
1288 static void __net_exit hashlimit_net_exit(struct net *net)
1289 {
1290         hashlimit_proc_net_exit(net);
1291 }
1292
1293 static struct pernet_operations hashlimit_net_ops = {
1294         .init   = hashlimit_net_init,
1295         .exit   = hashlimit_net_exit,
1296         .id     = &hashlimit_net_id,
1297         .size   = sizeof(struct hashlimit_net),
1298 };
1299
1300 static int __init hashlimit_mt_init(void)
1301 {
1302         int err;
1303
1304         err = register_pernet_subsys(&hashlimit_net_ops);
1305         if (err < 0)
1306                 return err;
1307         err = xt_register_matches(hashlimit_mt_reg,
1308               ARRAY_SIZE(hashlimit_mt_reg));
1309         if (err < 0)
1310                 goto err1;
1311
1312         err = -ENOMEM;
1313         hashlimit_cachep = kmem_cache_create("xt_hashlimit",
1314                                             sizeof(struct dsthash_ent), 0, 0,
1315                                             NULL);
1316         if (!hashlimit_cachep) {
1317                 pr_warn("unable to create slab cache\n");
1318                 goto err2;
1319         }
1320         return 0;
1321
1322 err2:
1323         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
1324 err1:
1325         unregister_pernet_subsys(&hashlimit_net_ops);
1326         return err;
1327
1328 }
1329
1330 static void __exit hashlimit_mt_exit(void)
1331 {
1332         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
1333         unregister_pernet_subsys(&hashlimit_net_ops);
1334
1335         rcu_barrier();
1336         kmem_cache_destroy(hashlimit_cachep);
1337 }
1338
1339 module_init(hashlimit_mt_init);
1340 module_exit(hashlimit_mt_exit);