net/netfilter/xt_recent.c

   1 /*
   2  * Copyright (c) 2006 Patrick McHardy <kaber@trash.net>
   3  * Copyright © CC Computer Consultants GmbH, 2007 - 2008
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  *
   9  * This is a replacement of the old ipt_recent module, which carried the
  10  * following copyright notice:
  11  *
  12  * Author: Stephen Frost <sfrost@snowman.net>
  13  * Copyright 2002-2003, Stephen Frost, 2.5.x port by laforge@netfilter.org
  14  */
  15 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  16 #include <linux/init.h>
  17 #include <linux/ip.h>
  18 #include <linux/ipv6.h>
  19 #include <linux/module.h>
  20 #include <linux/moduleparam.h>
  21 #include <linux/proc_fs.h>
  22 #include <linux/seq_file.h>
  23 #include <linux/string.h>
  24 #include <linux/ctype.h>
  25 #include <linux/list.h>
  26 #include <linux/random.h>
  27 #include <linux/jhash.h>
  28 #include <linux/bitops.h>
  29 #include <linux/skbuff.h>
  30 #include <linux/inet.h>
  31 #include <net/net_namespace.h>
  32 #include <net/netns/generic.h>
  33
  34 #include <linux/netfilter/x_tables.h>
  35 #include <linux/netfilter/xt_recent.h>
  36
  37 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
  38 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
  39 MODULE_DESCRIPTION("Xtables: \"recently-seen\" host matching");
  40 MODULE_LICENSE("GPL");
  41 MODULE_ALIAS("ipt_recent");
  42 MODULE_ALIAS("ip6t_recent");
  43
  44 static unsigned int ip_list_tot = 100;
  45 static unsigned int ip_pkt_list_tot = 20;
  46 static unsigned int ip_list_hash_size = 0;
  47 static unsigned int ip_list_perms = 0644;
  48 static unsigned int ip_list_uid = 0;
  49 static unsigned int ip_list_gid = 0;
  50 module_param(ip_list_tot, uint, 0400);
  51 module_param(ip_pkt_list_tot, uint, 0400);
  52 module_param(ip_list_hash_size, uint, 0400);
  53 module_param(ip_list_perms, uint, 0400);
  54 module_param(ip_list_uid, uint, S_IRUGO | S_IWUSR);
  55 module_param(ip_list_gid, uint, S_IRUGO | S_IWUSR);
  56 MODULE_PARM_DESC(ip_list_tot, "number of IPs to remember per list");
  57 MODULE_PARM_DESC(ip_pkt_list_tot, "number of packets per IP address to remember (max. 255)");
  58 MODULE_PARM_DESC(ip_list_hash_size, "size of hash table used to look up IPs");
  59 MODULE_PARM_DESC(ip_list_perms, "permissions on /proc/net/xt_recent/* files");
  60 MODULE_PARM_DESC(ip_list_uid, "default owner of /proc/net/xt_recent/* files");
  61 MODULE_PARM_DESC(ip_list_gid, "default owning group of /proc/net/xt_recent/* files");
  62
  63 struct recent_entry {
  64         struct list_head        list;
  65         struct list_head        lru_list;
  66         union nf_inet_addr      addr;
  67         u_int16_t               family;
  68         u_int8_t                ttl;
  69         u_int8_t                index;
  70         u_int16_t               nstamps;
  71         unsigned long           stamps[0];
  72 };
  73
  74 struct recent_table {
  75         struct list_head        list;
  76         char                    name[XT_RECENT_NAME_LEN];
  77         unsigned int            refcnt;
  78         unsigned int            entries;
  79         struct list_head        lru_list;
  80         struct list_head        iphash[0];
  81 };
  82
  83 struct recent_net {
  84         struct list_head        tables;
  85 #ifdef CONFIG_PROC_FS
  86         struct proc_dir_entry   *xt_recent;
  87 #endif
  88 };
  89
  90 static int recent_net_id;
  91 static inline struct recent_net *recent_pernet(struct net *net)
  92 {
  93         return net_generic(net, recent_net_id);
  94 }
  95
  96 static DEFINE_SPINLOCK(recent_lock);
  97 static DEFINE_MUTEX(recent_mutex);
  98
  99 #ifdef CONFIG_PROC_FS
 100 static const struct file_operations recent_old_fops, recent_mt_fops;
 101 #endif
 102
 103 static u_int32_t hash_rnd __read_mostly;
 104 static bool hash_rnd_inited __read_mostly;
 105
 106 static inline unsigned int recent_entry_hash4(const union nf_inet_addr *addr)
 107 {
 108         return jhash_1word((__force u32)addr->ip, hash_rnd) &
 109                (ip_list_hash_size - 1);
 110 }
 111
 112 static inline unsigned int recent_entry_hash6(const union nf_inet_addr *addr)
 113 {
 114         return jhash2((u32 *)addr->ip6, ARRAY_SIZE(addr->ip6), hash_rnd) &
 115                (ip_list_hash_size - 1);
 116 }
 117
 118 static struct recent_entry *
 119 recent_entry_lookup(const struct recent_table *table,
 120                     const union nf_inet_addr *addrp, u_int16_t family,
 121                     u_int8_t ttl)
 122 {
 123         struct recent_entry *e;
 124         unsigned int h;
 125
 126         if (family == NFPROTO_IPV4)
 127                 h = recent_entry_hash4(addrp);
 128         else
 129                 h = recent_entry_hash6(addrp);
 130
 131         list_for_each_entry(e, &table->iphash[h], list)
 132                 if (e->family == family &&
 133                     memcmp(&e->addr, addrp, sizeof(e->addr)) == 0 &&
 134                     (ttl == e->ttl || ttl == 0 || e->ttl == 0))
 135                         return e;
 136         return NULL;
 137 }
 138
 139 static void recent_entry_remove(struct recent_table *t, struct recent_entry *e)
 140 {
 141         list_del(&e->list);
 142         list_del(&e->lru_list);
 143         kfree(e);
 144         t->entries--;
 145 }
 146
 147 /*
 148  * Drop entries with timestamps older then 'time'.
 149  */
 150 static void recent_entry_reap(struct recent_table *t, unsigned long time)
 151 {
 152         struct recent_entry *e;
 153
 154         /*
 155          * The head of the LRU list is always the oldest entry.
 156          */
 157         e = list_entry(t->lru_list.next, struct recent_entry, lru_list);
 158
 159         /*
 160          * The last time stamp is the most recent.
 161          */
 162         if (time_after(time, e->stamps[e->index-1]))
 163                 recent_entry_remove(t, e);
 164 }
 165
 166 static struct recent_entry *
 167 recent_entry_init(struct recent_table *t, const union nf_inet_addr *addr,
 168                   u_int16_t family, u_int8_t ttl)
 169 {
 170         struct recent_entry *e;
 171
 172         if (t->entries >= ip_list_tot) {
 173                 e = list_entry(t->lru_list.next, struct recent_entry, lru_list);
 174                 recent_entry_remove(t, e);
 175         }
 176         e = kmalloc(sizeof(*e) + sizeof(e->stamps[0]) * ip_pkt_list_tot,
 177                     GFP_ATOMIC);
 178         if (e == NULL)
 179                 return NULL;
 180         memcpy(&e->addr, addr, sizeof(e->addr));
 181         e->ttl       = ttl;
 182         e->stamps[0] = jiffies;
 183         e->nstamps   = 1;
 184         e->index     = 1;
 185         e->family    = family;
 186         if (family == NFPROTO_IPV4)
 187                 list_add_tail(&e->list, &t->iphash[recent_entry_hash4(addr)]);
 188         else
 189                 list_add_tail(&e->list, &t->iphash[recent_entry_hash6(addr)]);
 190         list_add_tail(&e->lru_list, &t->lru_list);
 191         t->entries++;
 192         return e;
 193 }
 194
 195 static void recent_entry_update(struct recent_table *t, struct recent_entry *e)
 196 {
 197         e->index %= ip_pkt_list_tot;
 198         e->stamps[e->index++] = jiffies;
 199         if (e->index > e->nstamps)
 200                 e->nstamps = e->index;
 201         list_move_tail(&e->lru_list, &t->lru_list);
 202 }
 203
 204 static struct recent_table *recent_table_lookup(struct recent_net *recent_net,
 205                                                 const char *name)
 206 {
 207         struct recent_table *t;
 208
 209         list_for_each_entry(t, &recent_net->tables, list)
 210                 if (!strcmp(t->name, name))
 211                         return t;
 212         return NULL;
 213 }
 214
 215 static void recent_table_flush(struct recent_table *t)
 216 {
 217         struct recent_entry *e, *next;
 218         unsigned int i;
 219
 220         for (i = 0; i < ip_list_hash_size; i++)
 221                 list_for_each_entry_safe(e, next, &t->iphash[i], list)
 222                         recent_entry_remove(t, e);
 223 }
 224
 225 static bool
 226 recent_mt(const struct sk_buff *skb, const struct xt_match_param *par)
 227 {
 228         struct net *net = dev_net(par->in ? par->in : par->out);
 229         struct recent_net *recent_net = recent_pernet(net);
 230         const struct xt_recent_mtinfo *info = par->matchinfo;
 231         struct recent_table *t;
 232         struct recent_entry *e;
 233         union nf_inet_addr addr = {};
 234         u_int8_t ttl;
 235         bool ret = info->invert;
 236
 237         if (par->family == NFPROTO_IPV4) {
 238                 const struct iphdr *iph = ip_hdr(skb);
 239
 240                 if (info->side == XT_RECENT_DEST)
 241                         addr.ip = iph->daddr;
 242                 else
 243                         addr.ip = iph->saddr;
 244
 245                 ttl = iph->ttl;
 246         } else {
 247                 const struct ipv6hdr *iph = ipv6_hdr(skb);
 248
 249                 if (info->side == XT_RECENT_DEST)
 250                         memcpy(&addr.in6, &iph->daddr, sizeof(addr.in6));
 251                 else
 252                         memcpy(&addr.in6, &iph->saddr, sizeof(addr.in6));
 253
 254                 ttl = iph->hop_limit;
 255         }
 256
 257         /* use TTL as seen before forwarding */
 258         if (par->out != NULL && skb->sk == NULL)
 259                 ttl++;
 260
 261         spin_lock_bh(&recent_lock);
 262         t = recent_table_lookup(recent_net, info->name);
 263         e = recent_entry_lookup(t, &addr, par->family,
 264                                 (info->check_set & XT_RECENT_TTL) ? ttl : 0);
 265         if (e == NULL) {
 266                 if (!(info->check_set & XT_RECENT_SET))
 267                         goto out;
 268                 e = recent_entry_init(t, &addr, par->family, ttl);
 269                 if (e == NULL)
 270                         *par->hotdrop = true;
 271                 ret = !ret;
 272                 goto out;
 273         }
 274
 275         if (info->check_set & XT_RECENT_SET)
 276                 ret = !ret;
 277         else if (info->check_set & XT_RECENT_REMOVE) {
 278                 recent_entry_remove(t, e);
 279                 ret = !ret;
 280         } else if (info->check_set & (XT_RECENT_CHECK | XT_RECENT_UPDATE)) {
 281                 unsigned long time = jiffies - info->seconds * HZ;
 282                 unsigned int i, hits = 0;
 283
 284                 for (i = 0; i < e->nstamps; i++) {
 285                         if (info->seconds && time_after(time, e->stamps[i]))
 286                                 continue;
 287                         if (info->hit_count && ++hits >= info->hit_count) {
 288                                 ret = !ret;
 289                                 break;
 290                         }
 291                 }
 292
 293                 /* info->seconds must be non-zero */
 294                 if (info->check_set & XT_RECENT_REAP)
 295                         recent_entry_reap(t, time);
 296         }
 297
 298         if (info->check_set & XT_RECENT_SET ||
 299             (info->check_set & XT_RECENT_UPDATE && ret)) {
 300                 recent_entry_update(t, e);
 301                 e->ttl = ttl;
 302         }
 303 out:
 304         spin_unlock_bh(&recent_lock);
 305         return ret;
 306 }
 307
 308 static int recent_mt_check(const struct xt_mtchk_param *par)
 309 {
 310         struct recent_net *recent_net = recent_pernet(par->net);
 311         const struct xt_recent_mtinfo *info = par->matchinfo;
 312         struct recent_table *t;
 313 #ifdef CONFIG_PROC_FS
 314         struct proc_dir_entry *pde;
 315 #endif
 316         unsigned i;
 317         int ret = -EINVAL;
 318
 319         if (unlikely(!hash_rnd_inited)) {
 320                 get_random_bytes(&hash_rnd, sizeof(hash_rnd));
 321                 hash_rnd_inited = true;
 322         }
 323         if (info->check_set & ~XT_RECENT_VALID_FLAGS) {
 324                 pr_info("Unsupported user space flags (%08x)\n",
 325                         info->check_set);
 326                 return -EINVAL;
 327         }
 328         if (hweight8(info->check_set &
 329                      (XT_RECENT_SET | XT_RECENT_REMOVE |
 330                       XT_RECENT_CHECK | XT_RECENT_UPDATE)) != 1)
 331                 return -EINVAL;
 332         if ((info->check_set & (XT_RECENT_SET | XT_RECENT_REMOVE)) &&
 333             (info->seconds || info->hit_count ||
 334             (info->check_set & XT_RECENT_MODIFIERS)))
 335                 return -EINVAL;
 336         if ((info->check_set & XT_RECENT_REAP) && !info->seconds)
 337                 return -EINVAL;
 338         if (info->hit_count > ip_pkt_list_tot) {
 339                 pr_info("hitcount (%u) is larger than "
 340                         "packets to be remembered (%u)\n",
 341                         info->hit_count, ip_pkt_list_tot);
 342                 return -EINVAL;
 343         }
 344         if (info->name[0] == '\0' ||
 345             strnlen(info->name, XT_RECENT_NAME_LEN) == XT_RECENT_NAME_LEN)
 346                 return -EINVAL;
 347
 348         mutex_lock(&recent_mutex);
 349         t = recent_table_lookup(recent_net, info->name);
 350         if (t != NULL) {
 351                 t->refcnt++;
 352                 ret = 0;
 353                 goto out;
 354         }
 355
 356         t = kzalloc(sizeof(*t) + sizeof(t->iphash[0]) * ip_list_hash_size,
 357                     GFP_KERNEL);
 358         if (t == NULL)
 359                 goto out;
 360         t->refcnt = 1;
 361         strcpy(t->name, info->name);
 362         INIT_LIST_HEAD(&t->lru_list);
 363         for (i = 0; i < ip_list_hash_size; i++)
 364                 INIT_LIST_HEAD(&t->iphash[i]);
 365 #ifdef CONFIG_PROC_FS
 366         pde = proc_create_data(t->name, ip_list_perms, recent_net->xt_recent,
 367                   &recent_mt_fops, t);
 368         if (pde == NULL) {
 369                 kfree(t);
 370                 goto out;
 371         }
 372         pde->uid = ip_list_uid;
 373         pde->gid = ip_list_gid;
 374 #endif
 375         spin_lock_bh(&recent_lock);
 376         list_add_tail(&t->list, &recent_net->tables);
 377         spin_unlock_bh(&recent_lock);
 378         ret = 0;
 379 out:
 380         mutex_unlock(&recent_mutex);
 381         return ret;
 382 }
 383
 384 static void recent_mt_destroy(const struct xt_mtdtor_param *par)
 385 {
 386         struct recent_net *recent_net = recent_pernet(par->net);
 387         const struct xt_recent_mtinfo *info = par->matchinfo;
 388         struct recent_table *t;
 389
 390         mutex_lock(&recent_mutex);
 391         t = recent_table_lookup(recent_net, info->name);
 392         if (--t->refcnt == 0) {
 393                 spin_lock_bh(&recent_lock);
 394                 list_del(&t->list);
 395                 spin_unlock_bh(&recent_lock);
 396 #ifdef CONFIG_PROC_FS
 397                 remove_proc_entry(t->name, recent_net->xt_recent);
 398 #endif
 399                 recent_table_flush(t);
 400                 kfree(t);
 401         }
 402         mutex_unlock(&recent_mutex);
 403 }
 404
 405 #ifdef CONFIG_PROC_FS
 406 struct recent_iter_state {
 407         const struct recent_table *table;
 408         unsigned int            bucket;
 409 };
 410
 411 static void *recent_seq_start(struct seq_file *seq, loff_t *pos)
 412         __acquires(recent_lock)
 413 {
 414         struct recent_iter_state *st = seq->private;
 415         const struct recent_table *t = st->table;
 416         struct recent_entry *e;
 417         loff_t p = *pos;
 418
 419         spin_lock_bh(&recent_lock);
 420
 421         for (st->bucket = 0; st->bucket < ip_list_hash_size; st->bucket++)
 422                 list_for_each_entry(e, &t->iphash[st->bucket], list)
 423                         if (p-- == 0)
 424                                 return e;
 425         return NULL;
 426 }
 427
 428 static void *recent_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 429 {
 430         struct recent_iter_state *st = seq->private;
 431         const struct recent_table *t = st->table;
 432         const struct recent_entry *e = v;
 433         const struct list_head *head = e->list.next;
 434
 435         while (head == &t->iphash[st->bucket]) {
 436                 if (++st->bucket >= ip_list_hash_size)
 437                         return NULL;
 438                 head = t->iphash[st->bucket].next;
 439         }
 440         (*pos)++;
 441         return list_entry(head, struct recent_entry, list);
 442 }
 443
 444 static void recent_seq_stop(struct seq_file *s, void *v)
 445         __releases(recent_lock)
 446 {
 447         spin_unlock_bh(&recent_lock);
 448 }
 449
 450 static int recent_seq_show(struct seq_file *seq, void *v)
 451 {
 452         const struct recent_entry *e = v;
 453         unsigned int i;
 454
 455         i = (e->index - 1) % ip_pkt_list_tot;
 456         if (e->family == NFPROTO_IPV4)
 457                 seq_printf(seq, "src=%pI4 ttl: %u last_seen: %lu oldest_pkt: %u",
 458                            &e->addr.ip, e->ttl, e->stamps[i], e->index);
 459         else
 460                 seq_printf(seq, "src=%pI6 ttl: %u last_seen: %lu oldest_pkt: %u",
 461                            &e->addr.in6, e->ttl, e->stamps[i], e->index);
 462         for (i = 0; i < e->nstamps; i++)
 463                 seq_printf(seq, "%s %lu", i ? "," : "", e->stamps[i]);
 464         seq_printf(seq, "\n");
 465         return 0;
 466 }
 467
 468 static const struct seq_operations recent_seq_ops = {
 469         .start          = recent_seq_start,
 470         .next           = recent_seq_next,
 471         .stop           = recent_seq_stop,
 472         .show           = recent_seq_show,
 473 };
 474
 475 static int recent_seq_open(struct inode *inode, struct file *file)
 476 {
 477         struct proc_dir_entry *pde = PDE(inode);
 478         struct recent_iter_state *st;
 479
 480         st = __seq_open_private(file, &recent_seq_ops, sizeof(*st));
 481         if (st == NULL)
 482                 return -ENOMEM;
 483
 484         st->table    = pde->data;
 485         return 0;
 486 }
 487
 488 static ssize_t
 489 recent_mt_proc_write(struct file *file, const char __user *input,
 490                      size_t size, loff_t *loff)
 491 {
 492         const struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
 493         struct recent_table *t = pde->data;
 494         struct recent_entry *e;
 495         char buf[sizeof("+b335:1d35:1e55:dead:c0de:1715:5afe:c0de")];
 496         const char *c = buf;
 497         union nf_inet_addr addr = {};
 498         u_int16_t family;
 499         bool add, succ;
 500
 501         if (size == 0)
 502                 return 0;
 503         if (size > sizeof(buf))
 504                 size = sizeof(buf);
 505         if (copy_from_user(buf, input, size) != 0)
 506                 return -EFAULT;
 507
 508         /* Strict protocol! */
 509         if (*loff != 0)
 510                 return -ESPIPE;
 511         switch (*c) {
 512         case '/': /* flush table */
 513                 spin_lock_bh(&recent_lock);
 514                 recent_table_flush(t);
 515                 spin_unlock_bh(&recent_lock);
 516                 return size;
 517         case '-': /* remove address */
 518                 add = false;
 519                 break;
 520         case '+': /* add address */
 521                 add = true;
 522                 break;
 523         default:
 524                 pr_info("Need \"+ip\", \"-ip\" or \"/\"\n");
 525                 return -EINVAL;
 526         }
 527
 528         ++c;
 529         --size;
 530         if (strnchr(c, size, ':') != NULL) {
 531                 family = NFPROTO_IPV6;
 532                 succ   = in6_pton(c, size, (void *)&addr, '\n', NULL);
 533         } else {
 534                 family = NFPROTO_IPV4;
 535                 succ   = in4_pton(c, size, (void *)&addr, '\n', NULL);
 536         }
 537
 538         if (!succ) {
 539                 pr_info("illegal address written to procfs\n");
 540                 return -EINVAL;
 541         }
 542
 543         spin_lock_bh(&recent_lock);
 544         e = recent_entry_lookup(t, &addr, family, 0);
 545         if (e == NULL) {
 546                 if (add)
 547                         recent_entry_init(t, &addr, family, 0);
 548         } else {
 549                 if (add)
 550                         recent_entry_update(t, e);
 551                 else
 552                         recent_entry_remove(t, e);
 553         }
 554         spin_unlock_bh(&recent_lock);
 555         /* Note we removed one above */
 556         *loff += size + 1;
 557         return size + 1;
 558 }
 559
 560 static const struct file_operations recent_mt_fops = {
 561         .open    = recent_seq_open,
 562         .read    = seq_read,
 563         .write   = recent_mt_proc_write,
 564         .release = seq_release_private,
 565         .owner   = THIS_MODULE,
 566 };
 567
 568 static int __net_init recent_proc_net_init(struct net *net)
 569 {
 570         struct recent_net *recent_net = recent_pernet(net);
 571
 572         recent_net->xt_recent = proc_mkdir("xt_recent", net->proc_net);
 573         if (!recent_net->xt_recent)
 574                 return -ENOMEM;
 575         return 0;
 576 }
 577
 578 static void __net_exit recent_proc_net_exit(struct net *net)
 579 {
 580         proc_net_remove(net, "xt_recent");
 581 }
 582 #else
 583 static inline int recent_proc_net_init(struct net *net)
 584 {
 585         return 0;
 586 }
 587
 588 static inline void recent_proc_net_exit(struct net *net)
 589 {
 590 }
 591 #endif /* CONFIG_PROC_FS */
 592
 593 static int __net_init recent_net_init(struct net *net)
 594 {
 595         struct recent_net *recent_net = recent_pernet(net);
 596
 597         INIT_LIST_HEAD(&recent_net->tables);
 598         return recent_proc_net_init(net);
 599 }
 600
 601 static void __net_exit recent_net_exit(struct net *net)
 602 {
 603         struct recent_net *recent_net = recent_pernet(net);
 604
 605         BUG_ON(!list_empty(&recent_net->tables));
 606         recent_proc_net_exit(net);
 607 }
 608
 609 static struct pernet_operations recent_net_ops = {
 610         .init   = recent_net_init,
 611         .exit   = recent_net_exit,
 612         .id     = &recent_net_id,
 613         .size   = sizeof(struct recent_net),
 614 };
 615
 616 static struct xt_match recent_mt_reg[] __read_mostly = {
 617         {
 618                 .name       = "recent",
 619                 .revision   = 0,
 620                 .family     = NFPROTO_IPV4,
 621                 .match      = recent_mt,
 622                 .matchsize  = sizeof(struct xt_recent_mtinfo),
 623                 .checkentry = recent_mt_check,
 624                 .destroy    = recent_mt_destroy,
 625                 .me         = THIS_MODULE,
 626         },
 627         {
 628                 .name       = "recent",
 629                 .revision   = 0,
 630                 .family     = NFPROTO_IPV6,
 631                 .match      = recent_mt,
 632                 .matchsize  = sizeof(struct xt_recent_mtinfo),
 633                 .checkentry = recent_mt_check,
 634                 .destroy    = recent_mt_destroy,
 635                 .me         = THIS_MODULE,
 636         },
 637 };
 638
 639 static int __init recent_mt_init(void)
 640 {
 641         int err;
 642
 643         if (!ip_list_tot || !ip_pkt_list_tot || ip_pkt_list_tot > 255)
 644                 return -EINVAL;
 645         ip_list_hash_size = 1 << fls(ip_list_tot);
 646
 647         err = register_pernet_subsys(&recent_net_ops);
 648         if (err)
 649                 return err;
 650         err = xt_register_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
 651         if (err)
 652                 unregister_pernet_subsys(&recent_net_ops);
 653         return err;
 654 }
 655
 656 static void __exit recent_mt_exit(void)
 657 {
 658         xt_unregister_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
 659         unregister_pernet_subsys(&recent_net_ops);
 660 }
 661
 662 module_init(recent_mt_init);
 663 module_exit(recent_mt_exit);