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[];       /* 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 struct xt_hashlimit_htable *htable_find_get(struct net *net,
 406                                                    const char *name,
 407                                                    u_int8_t family)
 408 {
 409         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
 410         struct xt_hashlimit_htable *hinfo;
 411
 412         hlist_for_each_entry(hinfo, &hashlimit_net->htables, node) {
 413                 if (!strcmp(name, hinfo->name) &&
 414                     hinfo->family == family) {
 415                         refcount_inc(&hinfo->use);
 416                         return hinfo;
 417                 }
 418         }
 419         return NULL;
 420 }
 421
 422 static void htable_put(struct xt_hashlimit_htable *hinfo)
 423 {
 424         if (refcount_dec_and_mutex_lock(&hinfo->use, &hashlimit_mutex)) {
 425                 hlist_del(&hinfo->node);
 426                 htable_remove_proc_entry(hinfo);
 427                 mutex_unlock(&hashlimit_mutex);
 428
 429                 cancel_delayed_work_sync(&hinfo->gc_work);
 430                 htable_selective_cleanup(hinfo, true);
 431                 kfree(hinfo->name);
 432                 vfree(hinfo);
 433         }
 434 }
 435
 436 /* The algorithm used is the Simple Token Bucket Filter (TBF)
 437  * see net/sched/sch_tbf.c in the linux source tree
 438  */
 439
 440 /* Rusty: This is my (non-mathematically-inclined) understanding of
 441    this algorithm.  The `average rate' in jiffies becomes your initial
 442    amount of credit `credit' and the most credit you can ever have
 443    `credit_cap'.  The `peak rate' becomes the cost of passing the
 444    test, `cost'.
 445
 446    `prev' tracks the last packet hit: you gain one credit per jiffy.
 447    If you get credit balance more than this, the extra credit is
 448    discarded.  Every time the match passes, you lose `cost' credits;
 449    if you don't have that many, the test fails.
 450
 451    See Alexey's formal explanation in net/sched/sch_tbf.c.
 452
 453    To get the maximum range, we multiply by this factor (ie. you get N
 454    credits per jiffy).  We want to allow a rate as low as 1 per day
 455    (slowest userspace tool allows), which means
 456    CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
 457 */
 458 #define MAX_CPJ_v1 (0xFFFFFFFF / (HZ*60*60*24))
 459 #define MAX_CPJ (0xFFFFFFFFFFFFFFFFULL / (HZ*60*60*24))
 460
 461 /* Repeated shift and or gives us all 1s, final shift and add 1 gives
 462  * us the power of 2 below the theoretical max, so GCC simply does a
 463  * shift. */
 464 #define _POW2_BELOW2(x) ((x)|((x)>>1))
 465 #define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
 466 #define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
 467 #define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
 468 #define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
 469 #define _POW2_BELOW64(x) (_POW2_BELOW32(x)|_POW2_BELOW32((x)>>32))
 470 #define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
 471 #define POW2_BELOW64(x) ((_POW2_BELOW64(x)>>1) + 1)
 472
 473 #define CREDITS_PER_JIFFY POW2_BELOW64(MAX_CPJ)
 474 #define CREDITS_PER_JIFFY_v1 POW2_BELOW32(MAX_CPJ_v1)
 475
 476 /* in byte mode, the lowest possible rate is one packet/second.
 477  * credit_cap is used as a counter that tells us how many times we can
 478  * refill the "credits available" counter when it becomes empty.
 479  */
 480 #define MAX_CPJ_BYTES (0xFFFFFFFF / HZ)
 481 #define CREDITS_PER_JIFFY_BYTES POW2_BELOW32(MAX_CPJ_BYTES)
 482
 483 static u32 xt_hashlimit_len_to_chunks(u32 len)
 484 {
 485         return (len >> XT_HASHLIMIT_BYTE_SHIFT) + 1;
 486 }
 487
 488 /* Precision saver. */
 489 static u64 user2credits(u64 user, int revision)
 490 {
 491         u64 scale = (revision == 1) ?
 492                 XT_HASHLIMIT_SCALE : XT_HASHLIMIT_SCALE_v2;
 493         u64 cpj = (revision == 1) ?
 494                 CREDITS_PER_JIFFY_v1 : CREDITS_PER_JIFFY;
 495
 496         /* Avoid overflow: divide the constant operands first */
 497         if (scale >= HZ * cpj)
 498                 return div64_u64(user, div64_u64(scale, HZ * cpj));
 499
 500         return user * div64_u64(HZ * cpj, scale);
 501 }
 502
 503 static u32 user2credits_byte(u32 user)
 504 {
 505         u64 us = user;
 506         us *= HZ * CREDITS_PER_JIFFY_BYTES;
 507         return (u32) (us >> 32);
 508 }
 509
 510 static u64 user2rate(u64 user)
 511 {
 512         if (user != 0) {
 513                 return div64_u64(XT_HASHLIMIT_SCALE_v2, user);
 514         } else {
 515                 pr_info_ratelimited("invalid rate from userspace: %llu\n",
 516                                     user);
 517                 return 0;
 518         }
 519 }
 520
 521 static u64 user2rate_bytes(u32 user)
 522 {
 523         u64 r;
 524
 525         r = user ? U32_MAX / user : U32_MAX;
 526         return (r - 1) << XT_HASHLIMIT_BYTE_SHIFT;
 527 }
 528
 529 static void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now,
 530                             u32 mode, int revision)
 531 {
 532         unsigned long delta = now - dh->rateinfo.prev;
 533         u64 cap, cpj;
 534
 535         if (delta == 0)
 536                 return;
 537
 538         if (revision >= 3 && mode & XT_HASHLIMIT_RATE_MATCH) {
 539                 u64 interval = dh->rateinfo.interval * HZ;
 540
 541                 if (delta < interval)
 542                         return;
 543
 544                 dh->rateinfo.prev = now;
 545                 dh->rateinfo.prev_window =
 546                         ((dh->rateinfo.current_rate * interval) >
 547                          (delta * dh->rateinfo.rate));
 548                 dh->rateinfo.current_rate = 0;
 549
 550                 return;
 551         }
 552
 553         dh->rateinfo.prev = now;
 554
 555         if (mode & XT_HASHLIMIT_BYTES) {
 556                 u64 tmp = dh->rateinfo.credit;
 557                 dh->rateinfo.credit += CREDITS_PER_JIFFY_BYTES * delta;
 558                 cap = CREDITS_PER_JIFFY_BYTES * HZ;
 559                 if (tmp >= dh->rateinfo.credit) {/* overflow */
 560                         dh->rateinfo.credit = cap;
 561                         return;
 562                 }
 563         } else {
 564                 cpj = (revision == 1) ?
 565                         CREDITS_PER_JIFFY_v1 : CREDITS_PER_JIFFY;
 566                 dh->rateinfo.credit += delta * cpj;
 567                 cap = dh->rateinfo.credit_cap;
 568         }
 569         if (dh->rateinfo.credit > cap)
 570                 dh->rateinfo.credit = cap;
 571 }
 572
 573 static void rateinfo_init(struct dsthash_ent *dh,
 574                           struct xt_hashlimit_htable *hinfo, int revision)
 575 {
 576         dh->rateinfo.prev = jiffies;
 577         if (revision >= 3 && hinfo->cfg.mode & XT_HASHLIMIT_RATE_MATCH) {
 578                 dh->rateinfo.prev_window = 0;
 579                 dh->rateinfo.current_rate = 0;
 580                 if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) {
 581                         dh->rateinfo.rate =
 582                                 user2rate_bytes((u32)hinfo->cfg.avg);
 583                         if (hinfo->cfg.burst)
 584                                 dh->rateinfo.burst =
 585                                         hinfo->cfg.burst * dh->rateinfo.rate;
 586                         else
 587                                 dh->rateinfo.burst = dh->rateinfo.rate;
 588                 } else {
 589                         dh->rateinfo.rate = user2rate(hinfo->cfg.avg);
 590                         dh->rateinfo.burst =
 591                                 hinfo->cfg.burst + dh->rateinfo.rate;
 592                 }
 593                 dh->rateinfo.interval = hinfo->cfg.interval;
 594         } else if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) {
 595                 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
 596                 dh->rateinfo.cost = user2credits_byte(hinfo->cfg.avg);
 597                 dh->rateinfo.credit_cap = hinfo->cfg.burst;
 598         } else {
 599                 dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
 600                                                    hinfo->cfg.burst, revision);
 601                 dh->rateinfo.cost = user2credits(hinfo->cfg.avg, revision);
 602                 dh->rateinfo.credit_cap = dh->rateinfo.credit;
 603         }
 604 }
 605
 606 static inline __be32 maskl(__be32 a, unsigned int l)
 607 {
 608         return l ? htonl(ntohl(a) & ~0 << (32 - l)) : 0;
 609 }
 610
 611 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 612 static void hashlimit_ipv6_mask(__be32 *i, unsigned int p)
 613 {
 614         switch (p) {
 615         case 0 ... 31:
 616                 i[0] = maskl(i[0], p);
 617                 i[1] = i[2] = i[3] = 0;
 618                 break;
 619         case 32 ... 63:
 620                 i[1] = maskl(i[1], p - 32);
 621                 i[2] = i[3] = 0;
 622                 break;
 623         case 64 ... 95:
 624                 i[2] = maskl(i[2], p - 64);
 625                 i[3] = 0;
 626                 break;
 627         case 96 ... 127:
 628                 i[3] = maskl(i[3], p - 96);
 629                 break;
 630         case 128:
 631                 break;
 632         }
 633 }
 634 #endif
 635
 636 static int
 637 hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
 638                    struct dsthash_dst *dst,
 639                    const struct sk_buff *skb, unsigned int protoff)
 640 {
 641         __be16 _ports[2], *ports;
 642         u8 nexthdr;
 643         int poff;
 644
 645         memset(dst, 0, sizeof(*dst));
 646
 647         switch (hinfo->family) {
 648         case NFPROTO_IPV4:
 649                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
 650                         dst->ip.dst = maskl(ip_hdr(skb)->daddr,
 651                                       hinfo->cfg.dstmask);
 652                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
 653                         dst->ip.src = maskl(ip_hdr(skb)->saddr,
 654                                       hinfo->cfg.srcmask);
 655
 656                 if (!(hinfo->cfg.mode &
 657                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
 658                         return 0;
 659                 nexthdr = ip_hdr(skb)->protocol;
 660                 break;
 661 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 662         case NFPROTO_IPV6:
 663         {
 664                 __be16 frag_off;
 665
 666                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) {
 667                         memcpy(&dst->ip6.dst, &ipv6_hdr(skb)->daddr,
 668                                sizeof(dst->ip6.dst));
 669                         hashlimit_ipv6_mask(dst->ip6.dst, hinfo->cfg.dstmask);
 670                 }
 671                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) {
 672                         memcpy(&dst->ip6.src, &ipv6_hdr(skb)->saddr,
 673                                sizeof(dst->ip6.src));
 674                         hashlimit_ipv6_mask(dst->ip6.src, hinfo->cfg.srcmask);
 675                 }
 676
 677                 if (!(hinfo->cfg.mode &
 678                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
 679                         return 0;
 680                 nexthdr = ipv6_hdr(skb)->nexthdr;
 681                 protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, &frag_off);
 682                 if ((int)protoff < 0)
 683                         return -1;
 684                 break;
 685         }
 686 #endif
 687         default:
 688                 BUG();
 689                 return 0;
 690         }
 691
 692         poff = proto_ports_offset(nexthdr);
 693         if (poff >= 0) {
 694                 ports = skb_header_pointer(skb, protoff + poff, sizeof(_ports),
 695                                            &_ports);
 696         } else {
 697                 _ports[0] = _ports[1] = 0;
 698                 ports = _ports;
 699         }
 700         if (!ports)
 701                 return -1;
 702         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT)
 703                 dst->src_port = ports[0];
 704         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT)
 705                 dst->dst_port = ports[1];
 706         return 0;
 707 }
 708
 709 static u32 hashlimit_byte_cost(unsigned int len, struct dsthash_ent *dh)
 710 {
 711         u64 tmp = xt_hashlimit_len_to_chunks(len);
 712         tmp = tmp * dh->rateinfo.cost;
 713
 714         if (unlikely(tmp > CREDITS_PER_JIFFY_BYTES * HZ))
 715                 tmp = CREDITS_PER_JIFFY_BYTES * HZ;
 716
 717         if (dh->rateinfo.credit < tmp && dh->rateinfo.credit_cap) {
 718                 dh->rateinfo.credit_cap--;
 719                 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
 720         }
 721         return (u32) tmp;
 722 }
 723
 724 static bool
 725 hashlimit_mt_common(const struct sk_buff *skb, struct xt_action_param *par,
 726                     struct xt_hashlimit_htable *hinfo,
 727                     const struct hashlimit_cfg3 *cfg, int revision)
 728 {
 729         unsigned long now = jiffies;
 730         struct dsthash_ent *dh;
 731         struct dsthash_dst dst;
 732         bool race = false;
 733         u64 cost;
 734
 735         if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0)
 736                 goto hotdrop;
 737
 738         local_bh_disable();
 739         dh = dsthash_find(hinfo, &dst);
 740         if (dh == NULL) {
 741                 dh = dsthash_alloc_init(hinfo, &dst, &race);
 742                 if (dh == NULL) {
 743                         local_bh_enable();
 744                         goto hotdrop;
 745                 } else if (race) {
 746                         /* Already got an entry, update expiration timeout */
 747                         dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
 748                         rateinfo_recalc(dh, now, hinfo->cfg.mode, revision);
 749                 } else {
 750                         dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
 751                         rateinfo_init(dh, hinfo, revision);
 752                 }
 753         } else {
 754                 /* update expiration timeout */
 755                 dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
 756                 rateinfo_recalc(dh, now, hinfo->cfg.mode, revision);
 757         }
 758
 759         if (cfg->mode & XT_HASHLIMIT_RATE_MATCH) {
 760                 cost = (cfg->mode & XT_HASHLIMIT_BYTES) ? skb->len : 1;
 761                 dh->rateinfo.current_rate += cost;
 762
 763                 if (!dh->rateinfo.prev_window &&
 764                     (dh->rateinfo.current_rate <= dh->rateinfo.burst)) {
 765                         spin_unlock(&dh->lock);
 766                         local_bh_enable();
 767                         return !(cfg->mode & XT_HASHLIMIT_INVERT);
 768                 } else {
 769                         goto overlimit;
 770                 }
 771         }
 772
 773         if (cfg->mode & XT_HASHLIMIT_BYTES)
 774                 cost = hashlimit_byte_cost(skb->len, dh);
 775         else
 776                 cost = dh->rateinfo.cost;
 777
 778         if (dh->rateinfo.credit >= cost) {
 779                 /* below the limit */
 780                 dh->rateinfo.credit -= cost;
 781                 spin_unlock(&dh->lock);
 782                 local_bh_enable();
 783                 return !(cfg->mode & XT_HASHLIMIT_INVERT);
 784         }
 785
 786 overlimit:
 787         spin_unlock(&dh->lock);
 788         local_bh_enable();
 789         /* default match is underlimit - so over the limit, we need to invert */
 790         return cfg->mode & XT_HASHLIMIT_INVERT;
 791
 792  hotdrop:
 793         par->hotdrop = true;
 794         return false;
 795 }
 796
 797 static bool
 798 hashlimit_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
 799 {
 800         const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
 801         struct xt_hashlimit_htable *hinfo = info->hinfo;
 802         struct hashlimit_cfg3 cfg = {};
 803         int ret;
 804
 805         ret = cfg_copy(&cfg, (void *)&info->cfg, 1);
 806         if (ret)
 807                 return ret;
 808
 809         return hashlimit_mt_common(skb, par, hinfo, &cfg, 1);
 810 }
 811
 812 static bool
 813 hashlimit_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
 814 {
 815         const struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
 816         struct xt_hashlimit_htable *hinfo = info->hinfo;
 817         struct hashlimit_cfg3 cfg = {};
 818         int ret;
 819
 820         ret = cfg_copy(&cfg, (void *)&info->cfg, 2);
 821         if (ret)
 822                 return ret;
 823
 824         return hashlimit_mt_common(skb, par, hinfo, &cfg, 2);
 825 }
 826
 827 static bool
 828 hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par)
 829 {
 830         const struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
 831         struct xt_hashlimit_htable *hinfo = info->hinfo;
 832
 833         return hashlimit_mt_common(skb, par, hinfo, &info->cfg, 3);
 834 }
 835
 836 #define HASHLIMIT_MAX_SIZE 1048576
 837
 838 static int hashlimit_mt_check_common(const struct xt_mtchk_param *par,
 839                                      struct xt_hashlimit_htable **hinfo,
 840                                      struct hashlimit_cfg3 *cfg,
 841                                      const char *name, int revision)
 842 {
 843         struct net *net = par->net;
 844         int ret;
 845
 846         if (cfg->gc_interval == 0 || cfg->expire == 0)
 847                 return -EINVAL;
 848         if (cfg->size > HASHLIMIT_MAX_SIZE) {
 849                 cfg->size = HASHLIMIT_MAX_SIZE;
 850                 pr_info_ratelimited("size too large, truncated to %u\n", cfg->size);
 851         }
 852         if (cfg->max > HASHLIMIT_MAX_SIZE) {
 853                 cfg->max = HASHLIMIT_MAX_SIZE;
 854                 pr_info_ratelimited("max too large, truncated to %u\n", cfg->max);
 855         }
 856         if (par->family == NFPROTO_IPV4) {
 857                 if (cfg->srcmask > 32 || cfg->dstmask > 32)
 858                         return -EINVAL;
 859         } else {
 860                 if (cfg->srcmask > 128 || cfg->dstmask > 128)
 861                         return -EINVAL;
 862         }
 863
 864         if (cfg->mode & ~XT_HASHLIMIT_ALL) {
 865                 pr_info_ratelimited("Unknown mode mask %X, kernel too old?\n",
 866                                     cfg->mode);
 867                 return -EINVAL;
 868         }
 869
 870         /* Check for overflow. */
 871         if (revision >= 3 && cfg->mode & XT_HASHLIMIT_RATE_MATCH) {
 872                 if (cfg->avg == 0 || cfg->avg > U32_MAX) {
 873                         pr_info_ratelimited("invalid rate\n");
 874                         return -ERANGE;
 875                 }
 876
 877                 if (cfg->interval == 0) {
 878                         pr_info_ratelimited("invalid interval\n");
 879                         return -EINVAL;
 880                 }
 881         } else if (cfg->mode & XT_HASHLIMIT_BYTES) {
 882                 if (user2credits_byte(cfg->avg) == 0) {
 883                         pr_info_ratelimited("overflow, rate too high: %llu\n",
 884                                             cfg->avg);
 885                         return -EINVAL;
 886                 }
 887         } else if (cfg->burst == 0 ||
 888                    user2credits(cfg->avg * cfg->burst, revision) <
 889                    user2credits(cfg->avg, revision)) {
 890                 pr_info_ratelimited("overflow, try lower: %llu/%llu\n",
 891                                     cfg->avg, cfg->burst);
 892                 return -ERANGE;
 893         }
 894
 895         mutex_lock(&hashlimit_mutex);
 896         *hinfo = htable_find_get(net, name, par->family);
 897         if (*hinfo == NULL) {
 898                 ret = htable_create(net, cfg, name, par->family,
 899                                     hinfo, revision);
 900                 if (ret < 0) {
 901                         mutex_unlock(&hashlimit_mutex);
 902                         return ret;
 903                 }
 904         }
 905         mutex_unlock(&hashlimit_mutex);
 906
 907         return 0;
 908 }
 909
 910 static int hashlimit_mt_check_v1(const struct xt_mtchk_param *par)
 911 {
 912         struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
 913         struct hashlimit_cfg3 cfg = {};
 914         int ret;
 915
 916         ret = xt_check_proc_name(info->name, sizeof(info->name));
 917         if (ret)
 918                 return ret;
 919
 920         ret = cfg_copy(&cfg, (void *)&info->cfg, 1);
 921         if (ret)
 922                 return ret;
 923
 924         return hashlimit_mt_check_common(par, &info->hinfo,
 925                                          &cfg, info->name, 1);
 926 }
 927
 928 static int hashlimit_mt_check_v2(const struct xt_mtchk_param *par)
 929 {
 930         struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
 931         struct hashlimit_cfg3 cfg = {};
 932         int ret;
 933
 934         ret = xt_check_proc_name(info->name, sizeof(info->name));
 935         if (ret)
 936                 return ret;
 937
 938         ret = cfg_copy(&cfg, (void *)&info->cfg, 2);
 939         if (ret)
 940                 return ret;
 941
 942         return hashlimit_mt_check_common(par, &info->hinfo,
 943                                          &cfg, info->name, 2);
 944 }
 945
 946 static int hashlimit_mt_check(const struct xt_mtchk_param *par)
 947 {
 948         struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
 949         int ret;
 950
 951         ret = xt_check_proc_name(info->name, sizeof(info->name));
 952         if (ret)
 953                 return ret;
 954
 955         return hashlimit_mt_check_common(par, &info->hinfo, &info->cfg,
 956                                          info->name, 3);
 957 }
 958
 959 static void hashlimit_mt_destroy_v2(const struct xt_mtdtor_param *par)
 960 {
 961         const struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
 962
 963         htable_put(info->hinfo);
 964 }
 965
 966 static void hashlimit_mt_destroy_v1(const struct xt_mtdtor_param *par)
 967 {
 968         const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
 969
 970         htable_put(info->hinfo);
 971 }
 972
 973 static void hashlimit_mt_destroy(const struct xt_mtdtor_param *par)
 974 {
 975         const struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
 976
 977         htable_put(info->hinfo);
 978 }
 979
 980 static struct xt_match hashlimit_mt_reg[] __read_mostly = {
 981         {
 982                 .name           = "hashlimit",
 983                 .revision       = 1,
 984                 .family         = NFPROTO_IPV4,
 985                 .match          = hashlimit_mt_v1,
 986                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
 987                 .usersize       = offsetof(struct xt_hashlimit_mtinfo1, hinfo),
 988                 .checkentry     = hashlimit_mt_check_v1,
 989                 .destroy        = hashlimit_mt_destroy_v1,
 990                 .me             = THIS_MODULE,
 991         },
 992         {
 993                 .name           = "hashlimit",
 994                 .revision       = 2,
 995                 .family         = NFPROTO_IPV4,
 996                 .match          = hashlimit_mt_v2,
 997                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo2),
 998                 .usersize       = offsetof(struct xt_hashlimit_mtinfo2, hinfo),
 999                 .checkentry     = hashlimit_mt_check_v2,
1000                 .destroy        = hashlimit_mt_destroy_v2,
1001                 .me             = THIS_MODULE,
1002         },
1003         {
1004                 .name           = "hashlimit",
1005                 .revision       = 3,
1006                 .family         = NFPROTO_IPV4,
1007                 .match          = hashlimit_mt,
1008                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo3),
1009                 .usersize       = offsetof(struct xt_hashlimit_mtinfo3, hinfo),
1010                 .checkentry     = hashlimit_mt_check,
1011                 .destroy        = hashlimit_mt_destroy,
1012                 .me             = THIS_MODULE,
1013         },
1014 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1015         {
1016                 .name           = "hashlimit",
1017                 .revision       = 1,
1018                 .family         = NFPROTO_IPV6,
1019                 .match          = hashlimit_mt_v1,
1020                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
1021                 .usersize       = offsetof(struct xt_hashlimit_mtinfo1, hinfo),
1022                 .checkentry     = hashlimit_mt_check_v1,
1023                 .destroy        = hashlimit_mt_destroy_v1,
1024                 .me             = THIS_MODULE,
1025         },
1026         {
1027                 .name           = "hashlimit",
1028                 .revision       = 2,
1029                 .family         = NFPROTO_IPV6,
1030                 .match          = hashlimit_mt_v2,
1031                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo2),
1032                 .usersize       = offsetof(struct xt_hashlimit_mtinfo2, hinfo),
1033                 .checkentry     = hashlimit_mt_check_v2,
1034                 .destroy        = hashlimit_mt_destroy_v2,
1035                 .me             = THIS_MODULE,
1036         },
1037         {
1038                 .name           = "hashlimit",
1039                 .revision       = 3,
1040                 .family         = NFPROTO_IPV6,
1041                 .match          = hashlimit_mt,
1042                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo3),
1043                 .usersize       = offsetof(struct xt_hashlimit_mtinfo3, hinfo),
1044                 .checkentry     = hashlimit_mt_check,
1045                 .destroy        = hashlimit_mt_destroy,
1046                 .me             = THIS_MODULE,
1047         },
1048 #endif
1049 };
1050
1051 /* PROC stuff */
1052 static void *dl_seq_start(struct seq_file *s, loff_t *pos)
1053         __acquires(htable->lock)
1054 {
1055         struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file));
1056         unsigned int *bucket;
1057
1058         spin_lock_bh(&htable->lock);
1059         if (*pos >= htable->cfg.size)
1060                 return NULL;
1061
1062         bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
1063         if (!bucket)
1064                 return ERR_PTR(-ENOMEM);
1065
1066         *bucket = *pos;
1067         return bucket;
1068 }
1069
1070 static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
1071 {
1072         struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file));
1073         unsigned int *bucket = v;
1074
1075         *pos = ++(*bucket);
1076         if (*pos >= htable->cfg.size) {
1077                 kfree(v);
1078                 return NULL;
1079         }
1080         return bucket;
1081 }
1082
1083 static void dl_seq_stop(struct seq_file *s, void *v)
1084         __releases(htable->lock)
1085 {
1086         struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file));
1087         unsigned int *bucket = v;
1088
1089         if (!IS_ERR(bucket))
1090                 kfree(bucket);
1091         spin_unlock_bh(&htable->lock);
1092 }
1093
1094 static void dl_seq_print(struct dsthash_ent *ent, u_int8_t family,
1095                          struct seq_file *s)
1096 {
1097         switch (family) {
1098         case NFPROTO_IPV4:
1099                 seq_printf(s, "%ld %pI4:%u->%pI4:%u %llu %llu %llu\n",
1100                            (long)(ent->expires - jiffies)/HZ,
1101                            &ent->dst.ip.src,
1102                            ntohs(ent->dst.src_port),
1103                            &ent->dst.ip.dst,
1104                            ntohs(ent->dst.dst_port),
1105                            ent->rateinfo.credit, ent->rateinfo.credit_cap,
1106                            ent->rateinfo.cost);
1107                 break;
1108 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1109         case NFPROTO_IPV6:
1110                 seq_printf(s, "%ld %pI6:%u->%pI6:%u %llu %llu %llu\n",
1111                            (long)(ent->expires - jiffies)/HZ,
1112                            &ent->dst.ip6.src,
1113                            ntohs(ent->dst.src_port),
1114                            &ent->dst.ip6.dst,
1115                            ntohs(ent->dst.dst_port),
1116                            ent->rateinfo.credit, ent->rateinfo.credit_cap,
1117                            ent->rateinfo.cost);
1118                 break;
1119 #endif
1120         default:
1121                 BUG();
1122         }
1123 }
1124
1125 static int dl_seq_real_show_v2(struct dsthash_ent *ent, u_int8_t family,
1126                                struct seq_file *s)
1127 {
1128         struct xt_hashlimit_htable *ht = pde_data(file_inode(s->file));
1129
1130         spin_lock(&ent->lock);
1131         /* recalculate to show accurate numbers */
1132         rateinfo_recalc(ent, jiffies, ht->cfg.mode, 2);
1133
1134         dl_seq_print(ent, family, s);
1135
1136         spin_unlock(&ent->lock);
1137         return seq_has_overflowed(s);
1138 }
1139
1140 static int dl_seq_real_show_v1(struct dsthash_ent *ent, u_int8_t family,
1141                                struct seq_file *s)
1142 {
1143         struct xt_hashlimit_htable *ht = pde_data(file_inode(s->file));
1144
1145         spin_lock(&ent->lock);
1146         /* recalculate to show accurate numbers */
1147         rateinfo_recalc(ent, jiffies, ht->cfg.mode, 1);
1148
1149         dl_seq_print(ent, family, s);
1150
1151         spin_unlock(&ent->lock);
1152         return seq_has_overflowed(s);
1153 }
1154
1155 static int dl_seq_real_show(struct dsthash_ent *ent, u_int8_t family,
1156                             struct seq_file *s)
1157 {
1158         struct xt_hashlimit_htable *ht = pde_data(file_inode(s->file));
1159
1160         spin_lock(&ent->lock);
1161         /* recalculate to show accurate numbers */
1162         rateinfo_recalc(ent, jiffies, ht->cfg.mode, 3);
1163
1164         dl_seq_print(ent, family, s);
1165
1166         spin_unlock(&ent->lock);
1167         return seq_has_overflowed(s);
1168 }
1169
1170 static int dl_seq_show_v2(struct seq_file *s, void *v)
1171 {
1172         struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file));
1173         unsigned int *bucket = (unsigned int *)v;
1174         struct dsthash_ent *ent;
1175
1176         if (!hlist_empty(&htable->hash[*bucket])) {
1177                 hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1178                         if (dl_seq_real_show_v2(ent, htable->family, s))
1179                                 return -1;
1180         }
1181         return 0;
1182 }
1183
1184 static int dl_seq_show_v1(struct seq_file *s, void *v)
1185 {
1186         struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file));
1187         unsigned int *bucket = v;
1188         struct dsthash_ent *ent;
1189
1190         if (!hlist_empty(&htable->hash[*bucket])) {
1191                 hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1192                         if (dl_seq_real_show_v1(ent, htable->family, s))
1193                                 return -1;
1194         }
1195         return 0;
1196 }
1197
1198 static int dl_seq_show(struct seq_file *s, void *v)
1199 {
1200         struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file));
1201         unsigned int *bucket = v;
1202         struct dsthash_ent *ent;
1203
1204         if (!hlist_empty(&htable->hash[*bucket])) {
1205                 hlist_for_each_entry(ent, &htable->hash[*bucket], node)
1206                         if (dl_seq_real_show(ent, htable->family, s))
1207                                 return -1;
1208         }
1209         return 0;
1210 }
1211
1212 static const struct seq_operations dl_seq_ops_v1 = {
1213         .start = dl_seq_start,
1214         .next  = dl_seq_next,
1215         .stop  = dl_seq_stop,
1216         .show  = dl_seq_show_v1
1217 };
1218
1219 static const struct seq_operations dl_seq_ops_v2 = {
1220         .start = dl_seq_start,
1221         .next  = dl_seq_next,
1222         .stop  = dl_seq_stop,
1223         .show  = dl_seq_show_v2
1224 };
1225
1226 static const struct seq_operations dl_seq_ops = {
1227         .start = dl_seq_start,
1228         .next  = dl_seq_next,
1229         .stop  = dl_seq_stop,
1230         .show  = dl_seq_show
1231 };
1232
1233 static int __net_init hashlimit_proc_net_init(struct net *net)
1234 {
1235         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1236
1237         hashlimit_net->ipt_hashlimit = proc_mkdir("ipt_hashlimit", net->proc_net);
1238         if (!hashlimit_net->ipt_hashlimit)
1239                 return -ENOMEM;
1240 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1241         hashlimit_net->ip6t_hashlimit = proc_mkdir("ip6t_hashlimit", net->proc_net);
1242         if (!hashlimit_net->ip6t_hashlimit) {
1243                 remove_proc_entry("ipt_hashlimit", net->proc_net);
1244                 return -ENOMEM;
1245         }
1246 #endif
1247         return 0;
1248 }
1249
1250 static void __net_exit hashlimit_proc_net_exit(struct net *net)
1251 {
1252         struct xt_hashlimit_htable *hinfo;
1253         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1254
1255         /* hashlimit_net_exit() is called before hashlimit_mt_destroy().
1256          * Make sure that the parent ipt_hashlimit and ip6t_hashlimit proc
1257          * entries is empty before trying to remove it.
1258          */
1259         mutex_lock(&hashlimit_mutex);
1260         hlist_for_each_entry(hinfo, &hashlimit_net->htables, node)
1261                 htable_remove_proc_entry(hinfo);
1262         hashlimit_net->ipt_hashlimit = NULL;
1263         hashlimit_net->ip6t_hashlimit = NULL;
1264         mutex_unlock(&hashlimit_mutex);
1265
1266         remove_proc_entry("ipt_hashlimit", net->proc_net);
1267 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
1268         remove_proc_entry("ip6t_hashlimit", net->proc_net);
1269 #endif
1270 }
1271
1272 static int __net_init hashlimit_net_init(struct net *net)
1273 {
1274         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
1275
1276         INIT_HLIST_HEAD(&hashlimit_net->htables);
1277         return hashlimit_proc_net_init(net);
1278 }
1279
1280 static void __net_exit hashlimit_net_exit(struct net *net)
1281 {
1282         hashlimit_proc_net_exit(net);
1283 }
1284
1285 static struct pernet_operations hashlimit_net_ops = {
1286         .init   = hashlimit_net_init,
1287         .exit   = hashlimit_net_exit,
1288         .id     = &hashlimit_net_id,
1289         .size   = sizeof(struct hashlimit_net),
1290 };
1291
1292 static int __init hashlimit_mt_init(void)
1293 {
1294         int err;
1295
1296         err = register_pernet_subsys(&hashlimit_net_ops);
1297         if (err < 0)
1298                 return err;
1299         err = xt_register_matches(hashlimit_mt_reg,
1300               ARRAY_SIZE(hashlimit_mt_reg));
1301         if (err < 0)
1302                 goto err1;
1303
1304         err = -ENOMEM;
1305         hashlimit_cachep = kmem_cache_create("xt_hashlimit",
1306                                             sizeof(struct dsthash_ent), 0, 0,
1307                                             NULL);
1308         if (!hashlimit_cachep) {
1309                 pr_warn("unable to create slab cache\n");
1310                 goto err2;
1311         }
1312         return 0;
1313
1314 err2:
1315         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
1316 err1:
1317         unregister_pernet_subsys(&hashlimit_net_ops);
1318         return err;
1319
1320 }
1321
1322 static void __exit hashlimit_mt_exit(void)
1323 {
1324         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
1325         unregister_pernet_subsys(&hashlimit_net_ops);
1326
1327         rcu_barrier();
1328         kmem_cache_destroy(hashlimit_cachep);
1329 }
1330
1331 module_init(hashlimit_mt_init);
1332 module_exit(hashlimit_mt_exit);