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 <linux/slab.h>
  32 #include <net/net_namespace.h>
  33 #include <net/netns/generic.h>
  34
  35 #include <linux/netfilter/x_tables.h>
  36 #include <linux/netfilter/xt_recent.h>
  37
  38 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
  39 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
  40 MODULE_DESCRIPTION("Xtables: \"recently-seen\" host matching");
  41 MODULE_LICENSE("GPL");
  42 MODULE_ALIAS("ipt_recent");
  43 MODULE_ALIAS("ip6t_recent");
  44
  45 static unsigned int ip_list_tot = 100;
  46 static unsigned int ip_pkt_list_tot = 20;
  47 static unsigned int ip_list_hash_size = 0;
  48 static unsigned int ip_list_perms = 0644;
  49 static unsigned int ip_list_uid = 0;
  50 static unsigned int ip_list_gid = 0;
  51 module_param(ip_list_tot, uint, 0400);
  52 module_param(ip_pkt_list_tot, uint, 0400);
  53 module_param(ip_list_hash_size, uint, 0400);
  54 module_param(ip_list_perms, uint, 0400);
  55 module_param(ip_list_uid, uint, S_IRUGO | S_IWUSR);
  56 module_param(ip_list_gid, uint, S_IRUGO | S_IWUSR);
  57 MODULE_PARM_DESC(ip_list_tot, "number of IPs to remember per list");
  58 MODULE_PARM_DESC(ip_pkt_list_tot, "number of packets per IP address to remember (max. 255)");
  59 MODULE_PARM_DESC(ip_list_hash_size, "size of hash table used to look up IPs");
  60 MODULE_PARM_DESC(ip_list_perms, "permissions on /proc/net/xt_recent/* files");
  61 MODULE_PARM_DESC(ip_list_uid, "default owner of /proc/net/xt_recent/* files");
  62 MODULE_PARM_DESC(ip_list_gid, "default owning group of /proc/net/xt_recent/* files");
  63
  64 struct recent_entry {
  65         struct list_head        list;
  66         struct list_head        lru_list;
  67         union nf_inet_addr      addr;
  68         u_int16_t               family;
  69         u_int8_t                ttl;
  70         u_int8_t                index;
  71         u_int16_t               nstamps;
  72         unsigned long           stamps[0];
  73 };
  74
  75 struct recent_table {
  76         struct list_head        list;
  77         char                    name[XT_RECENT_NAME_LEN];
  78         unsigned int            refcnt;
  79         unsigned int            entries;
  80         struct list_head        lru_list;
  81         struct list_head        iphash[0];
  82 };
  83
  84 struct recent_net {
  85         struct list_head        tables;
  86 #ifdef CONFIG_PROC_FS
  87         struct proc_dir_entry   *xt_recent;
  88 #endif
  89 };
  90
  91 static int recent_net_id;
  92 static inline struct recent_net *recent_pernet(struct net *net)
  93 {
  94         return net_generic(net, recent_net_id);
  95 }
  96
  97 static DEFINE_SPINLOCK(recent_lock);
  98 static DEFINE_MUTEX(recent_mutex);
  99
 100 #ifdef CONFIG_PROC_FS
 101 static const struct file_operations recent_old_fops, recent_mt_fops;
 102 #endif
 103
 104 static u_int32_t hash_rnd __read_mostly;
 105 static bool hash_rnd_inited __read_mostly;
 106
 107 static inline unsigned int recent_entry_hash4(const union nf_inet_addr *addr)
 108 {
 109         return jhash_1word((__force u32)addr->ip, hash_rnd) &
 110                (ip_list_hash_size - 1);
 111 }
 112
 113 static inline unsigned int recent_entry_hash6(const union nf_inet_addr *addr)
 114 {
 115         return jhash2((u32 *)addr->ip6, ARRAY_SIZE(addr->ip6), hash_rnd) &
 116                (ip_list_hash_size - 1);
 117 }
 118
 119 static struct recent_entry *
 120 recent_entry_lookup(const struct recent_table *table,
 121                     const union nf_inet_addr *addrp, u_int16_t family,
 122                     u_int8_t ttl)
 123 {
 124         struct recent_entry *e;
 125         unsigned int h;
 126
 127         if (family == NFPROTO_IPV4)
 128                 h = recent_entry_hash4(addrp);
 129         else
 130                 h = recent_entry_hash6(addrp);
 131
 132         list_for_each_entry(e, &table->iphash[h], list)
 133                 if (e->family == family &&
 134                     memcmp(&e->addr, addrp, sizeof(e->addr)) == 0 &&
 135                     (ttl == e->ttl || ttl == 0 || e->ttl == 0))
 136                         return e;
 137         return NULL;
 138 }
 139
 140 static void recent_entry_remove(struct recent_table *t, struct recent_entry *e)
 141 {
 142         list_del(&e->list);
 143         list_del(&e->lru_list);
 144         kfree(e);
 145         t->entries--;
 146 }
 147
 148 /*
 149  * Drop entries with timestamps older then 'time'.
 150  */
 151 static void recent_entry_reap(struct recent_table *t, unsigned long time)
 152 {
 153         struct recent_entry *e;
 154
 155         /*
 156          * The head of the LRU list is always the oldest entry.
 157          */
 158         e = list_entry(t->lru_list.next, struct recent_entry, lru_list);
 159
 160         /*
 161          * The last time stamp is the most recent.
 162          */
 163         if (time_after(time, e->stamps[e->index-1]))
 164                 recent_entry_remove(t, e);
 165 }
 166
 167 static struct recent_entry *
 168 recent_entry_init(struct recent_table *t, const union nf_inet_addr *addr,
 169                   u_int16_t family, u_int8_t ttl)
 170 {
 171         struct recent_entry *e;
 172
 173         if (t->entries >= ip_list_tot) {
 174                 e = list_entry(t->lru_list.next, struct recent_entry, lru_list);
 175                 recent_entry_remove(t, e);
 176         }
 177         e = kmalloc(sizeof(*e) + sizeof(e->stamps[0]) * ip_pkt_list_tot,
 178                     GFP_ATOMIC);
 179         if (e == NULL)
 180                 return NULL;
 181         memcpy(&e->addr, addr, sizeof(e->addr));
 182         e->ttl       = ttl;
 183         e->stamps[0] = jiffies;
 184         e->nstamps   = 1;
 185         e->index     = 1;
 186         e->family    = family;
 187         if (family == NFPROTO_IPV4)
 188                 list_add_tail(&e->list, &t->iphash[recent_entry_hash4(addr)]);
 189         else
 190                 list_add_tail(&e->list, &t->iphash[recent_entry_hash6(addr)]);
 191         list_add_tail(&e->lru_list, &t->lru_list);
 192         t->entries++;
 193         return e;
 194 }
 195
 196 static void recent_entry_update(struct recent_table *t, struct recent_entry *e)
 197 {
 198         e->index %= ip_pkt_list_tot;
 199         e->stamps[e->index++] = jiffies;
 200         if (e->index > e->nstamps)
 201                 e->nstamps = e->index;
 202         list_move_tail(&e->lru_list, &t->lru_list);
 203 }
 204
 205 static struct recent_table *recent_table_lookup(struct recent_net *recent_net,
 206                                                 const char *name)
 207 {
 208         struct recent_table *t;
 209
 210         list_for_each_entry(t, &recent_net->tables, list)
 211                 if (!strcmp(t->name, name))
 212                         return t;
 213         return NULL;
 214 }
 215
 216 static void recent_table_flush(struct recent_table *t)
 217 {
 218         struct recent_entry *e, *next;
 219         unsigned int i;
 220
 221         for (i = 0; i < ip_list_hash_size; i++)
 222                 list_for_each_entry_safe(e, next, &t->iphash[i], list)
 223                         recent_entry_remove(t, e);
 224 }
 225
 226 static bool
 227 recent_mt(const struct sk_buff *skb, struct xt_action_param *par)
 228 {
 229         struct net *net = dev_net(par->in ? par->in : par->out);
 230         struct recent_net *recent_net = recent_pernet(net);
 231         const struct xt_recent_mtinfo *info = par->matchinfo;
 232         struct recent_table *t;
 233         struct recent_entry *e;
 234         union nf_inet_addr addr = {};
 235         u_int8_t ttl;
 236         bool ret = info->invert;
 237
 238         if (par->family == NFPROTO_IPV4) {
 239                 const struct iphdr *iph = ip_hdr(skb);
 240
 241                 if (info->side == XT_RECENT_DEST)
 242                         addr.ip = iph->daddr;
 243                 else
 244                         addr.ip = iph->saddr;
 245
 246                 ttl = iph->ttl;
 247         } else {
 248                 const struct ipv6hdr *iph = ipv6_hdr(skb);
 249
 250                 if (info->side == XT_RECENT_DEST)
 251                         memcpy(&addr.in6, &iph->daddr, sizeof(addr.in6));
 252                 else
 253                         memcpy(&addr.in6, &iph->saddr, sizeof(addr.in6));
 254
 255                 ttl = iph->hop_limit;
 256         }
 257
 258         /* use TTL as seen before forwarding */
 259         if (par->out != NULL && skb->sk == NULL)
 260                 ttl++;
 261
 262         spin_lock_bh(&recent_lock);
 263         t = recent_table_lookup(recent_net, info->name);
 264         e = recent_entry_lookup(t, &addr, par->family,
 265                                 (info->check_set & XT_RECENT_TTL) ? ttl : 0);
 266         if (e == NULL) {
 267                 if (!(info->check_set & XT_RECENT_SET))
 268                         goto out;
 269                 e = recent_entry_init(t, &addr, par->family, ttl);
 270                 if (e == NULL)
 271                         par->hotdrop = true;
 272                 ret = !ret;
 273                 goto out;
 274         }
 275
 276         if (info->check_set & XT_RECENT_SET)
 277                 ret = !ret;
 278         else if (info->check_set & XT_RECENT_REMOVE) {
 279                 recent_entry_remove(t, e);
 280                 ret = !ret;
 281         } else if (info->check_set & (XT_RECENT_CHECK | XT_RECENT_UPDATE)) {
 282                 unsigned long time = jiffies - info->seconds * HZ;
 283                 unsigned int i, hits = 0;
 284
 285                 for (i = 0; i < e->nstamps; i++) {
 286                         if (info->seconds && time_after(time, e->stamps[i]))
 287                                 continue;
 288                         if (!info->hit_count || ++hits >= info->hit_count) {
 289                                 ret = !ret;
 290                                 break;
 291                         }
 292                 }
 293
 294                 /* info->seconds must be non-zero */
 295                 if (info->check_set & XT_RECENT_REAP)
 296                         recent_entry_reap(t, time);
 297         }
 298
 299         if (info->check_set & XT_RECENT_SET ||
 300             (info->check_set & XT_RECENT_UPDATE && ret)) {
 301                 recent_entry_update(t, e);
 302                 e->ttl = ttl;
 303         }
 304 out:
 305         spin_unlock_bh(&recent_lock);
 306         return ret;
 307 }
 308
 309 static int recent_mt_check(const struct xt_mtchk_param *par)
 310 {
 311         struct recent_net *recent_net = recent_pernet(par->net);
 312         const struct xt_recent_mtinfo *info = par->matchinfo;
 313         struct recent_table *t;
 314 #ifdef CONFIG_PROC_FS
 315         struct proc_dir_entry *pde;
 316 #endif
 317         unsigned i;
 318         int ret = -EINVAL;
 319
 320         if (unlikely(!hash_rnd_inited)) {
 321                 get_random_bytes(&hash_rnd, sizeof(hash_rnd));
 322                 hash_rnd_inited = true;
 323         }
 324         if (info->check_set & ~XT_RECENT_VALID_FLAGS) {
 325                 pr_info("Unsupported user space flags (%08x)\n",
 326                         info->check_set);
 327                 return -EINVAL;
 328         }
 329         if (hweight8(info->check_set &
 330                      (XT_RECENT_SET | XT_RECENT_REMOVE |
 331                       XT_RECENT_CHECK | XT_RECENT_UPDATE)) != 1)
 332                 return -EINVAL;
 333         if ((info->check_set & (XT_RECENT_SET | XT_RECENT_REMOVE)) &&
 334             (info->seconds || info->hit_count ||
 335             (info->check_set & XT_RECENT_MODIFIERS)))
 336                 return -EINVAL;
 337         if ((info->check_set & XT_RECENT_REAP) && !info->seconds)
 338                 return -EINVAL;
 339         if (info->hit_count > ip_pkt_list_tot) {
 340                 pr_info("hitcount (%u) is larger than "
 341                         "packets to be remembered (%u)\n",
 342                         info->hit_count, ip_pkt_list_tot);
 343                 return -EINVAL;
 344         }
 345         if (info->name[0] == '\0' ||
 346             strnlen(info->name, XT_RECENT_NAME_LEN) == XT_RECENT_NAME_LEN)
 347                 return -EINVAL;
 348
 349         mutex_lock(&recent_mutex);
 350         t = recent_table_lookup(recent_net, info->name);
 351         if (t != NULL) {
 352                 t->refcnt++;
 353                 ret = 0;
 354                 goto out;
 355         }
 356
 357         t = kzalloc(sizeof(*t) + sizeof(t->iphash[0]) * ip_list_hash_size,
 358                     GFP_KERNEL);
 359         if (t == NULL) {
 360                 ret = -ENOMEM;
 361                 goto out;
 362         }
 363         t->refcnt = 1;
 364         strcpy(t->name, info->name);
 365         INIT_LIST_HEAD(&t->lru_list);
 366         for (i = 0; i < ip_list_hash_size; i++)
 367                 INIT_LIST_HEAD(&t->iphash[i]);
 368 #ifdef CONFIG_PROC_FS
 369         pde = proc_create_data(t->name, ip_list_perms, recent_net->xt_recent,
 370                   &recent_mt_fops, t);
 371         if (pde == NULL) {
 372                 kfree(t);
 373                 ret = -ENOMEM;
 374                 goto out;
 375         }
 376         pde->uid = ip_list_uid;
 377         pde->gid = ip_list_gid;
 378 #endif
 379         spin_lock_bh(&recent_lock);
 380         list_add_tail(&t->list, &recent_net->tables);
 381         spin_unlock_bh(&recent_lock);
 382         ret = 0;
 383 out:
 384         mutex_unlock(&recent_mutex);
 385         return ret;
 386 }
 387
 388 static void recent_mt_destroy(const struct xt_mtdtor_param *par)
 389 {
 390         struct recent_net *recent_net = recent_pernet(par->net);
 391         const struct xt_recent_mtinfo *info = par->matchinfo;
 392         struct recent_table *t;
 393
 394         mutex_lock(&recent_mutex);
 395         t = recent_table_lookup(recent_net, info->name);
 396         if (--t->refcnt == 0) {
 397                 spin_lock_bh(&recent_lock);
 398                 list_del(&t->list);
 399                 spin_unlock_bh(&recent_lock);
 400 #ifdef CONFIG_PROC_FS
 401                 remove_proc_entry(t->name, recent_net->xt_recent);
 402 #endif
 403                 recent_table_flush(t);
 404                 kfree(t);
 405         }
 406         mutex_unlock(&recent_mutex);
 407 }
 408
 409 #ifdef CONFIG_PROC_FS
 410 struct recent_iter_state {
 411         const struct recent_table *table;
 412         unsigned int            bucket;
 413 };
 414
 415 static void *recent_seq_start(struct seq_file *seq, loff_t *pos)
 416         __acquires(recent_lock)
 417 {
 418         struct recent_iter_state *st = seq->private;
 419         const struct recent_table *t = st->table;
 420         struct recent_entry *e;
 421         loff_t p = *pos;
 422
 423         spin_lock_bh(&recent_lock);
 424
 425         for (st->bucket = 0; st->bucket < ip_list_hash_size; st->bucket++)
 426                 list_for_each_entry(e, &t->iphash[st->bucket], list)
 427                         if (p-- == 0)
 428                                 return e;
 429         return NULL;
 430 }
 431
 432 static void *recent_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 433 {
 434         struct recent_iter_state *st = seq->private;
 435         const struct recent_table *t = st->table;
 436         const struct recent_entry *e = v;
 437         const struct list_head *head = e->list.next;
 438
 439         while (head == &t->iphash[st->bucket]) {
 440                 if (++st->bucket >= ip_list_hash_size)
 441                         return NULL;
 442                 head = t->iphash[st->bucket].next;
 443         }
 444         (*pos)++;
 445         return list_entry(head, struct recent_entry, list);
 446 }
 447
 448 static void recent_seq_stop(struct seq_file *s, void *v)
 449         __releases(recent_lock)
 450 {
 451         spin_unlock_bh(&recent_lock);
 452 }
 453
 454 static int recent_seq_show(struct seq_file *seq, void *v)
 455 {
 456         const struct recent_entry *e = v;
 457         unsigned int i;
 458
 459         i = (e->index - 1) % ip_pkt_list_tot;
 460         if (e->family == NFPROTO_IPV4)
 461                 seq_printf(seq, "src=%pI4 ttl: %u last_seen: %lu oldest_pkt: %u",
 462                            &e->addr.ip, e->ttl, e->stamps[i], e->index);
 463         else
 464                 seq_printf(seq, "src=%pI6 ttl: %u last_seen: %lu oldest_pkt: %u",
 465                            &e->addr.in6, e->ttl, e->stamps[i], e->index);
 466         for (i = 0; i < e->nstamps; i++)
 467                 seq_printf(seq, "%s %lu", i ? "," : "", e->stamps[i]);
 468         seq_printf(seq, "\n");
 469         return 0;
 470 }
 471
 472 static const struct seq_operations recent_seq_ops = {
 473         .start          = recent_seq_start,
 474         .next           = recent_seq_next,
 475         .stop           = recent_seq_stop,
 476         .show           = recent_seq_show,
 477 };
 478
 479 static int recent_seq_open(struct inode *inode, struct file *file)
 480 {
 481         struct proc_dir_entry *pde = PDE(inode);
 482         struct recent_iter_state *st;
 483
 484         st = __seq_open_private(file, &recent_seq_ops, sizeof(*st));
 485         if (st == NULL)
 486                 return -ENOMEM;
 487
 488         st->table    = pde->data;
 489         return 0;
 490 }
 491
 492 static ssize_t
 493 recent_mt_proc_write(struct file *file, const char __user *input,
 494                      size_t size, loff_t *loff)
 495 {
 496         const struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
 497         struct recent_table *t = pde->data;
 498         struct recent_entry *e;
 499         char buf[sizeof("+b335:1d35:1e55:dead:c0de:1715:5afe:c0de")];
 500         const char *c = buf;
 501         union nf_inet_addr addr = {};
 502         u_int16_t family;
 503         bool add, succ;
 504
 505         if (size == 0)
 506                 return 0;
 507         if (size > sizeof(buf))
 508                 size = sizeof(buf);
 509         if (copy_from_user(buf, input, size) != 0)
 510                 return -EFAULT;
 511
 512         /* Strict protocol! */
 513         if (*loff != 0)
 514                 return -ESPIPE;
 515         switch (*c) {
 516         case '/': /* flush table */
 517                 spin_lock_bh(&recent_lock);
 518                 recent_table_flush(t);
 519                 spin_unlock_bh(&recent_lock);
 520                 return size;
 521         case '-': /* remove address */
 522                 add = false;
 523                 break;
 524         case '+': /* add address */
 525                 add = true;
 526                 break;
 527         default:
 528                 pr_info("Need \"+ip\", \"-ip\" or \"/\"\n");
 529                 return -EINVAL;
 530         }
 531
 532         ++c;
 533         --size;
 534         if (strnchr(c, size, ':') != NULL) {
 535                 family = NFPROTO_IPV6;
 536                 succ   = in6_pton(c, size, (void *)&addr, '\n', NULL);
 537         } else {
 538                 family = NFPROTO_IPV4;
 539                 succ   = in4_pton(c, size, (void *)&addr, '\n', NULL);
 540         }
 541
 542         if (!succ) {
 543                 pr_info("illegal address written to procfs\n");
 544                 return -EINVAL;
 545         }
 546
 547         spin_lock_bh(&recent_lock);
 548         e = recent_entry_lookup(t, &addr, family, 0);
 549         if (e == NULL) {
 550                 if (add)
 551                         recent_entry_init(t, &addr, family, 0);
 552         } else {
 553                 if (add)
 554                         recent_entry_update(t, e);
 555                 else
 556                         recent_entry_remove(t, e);
 557         }
 558         spin_unlock_bh(&recent_lock);
 559         /* Note we removed one above */
 560         *loff += size + 1;
 561         return size + 1;
 562 }
 563
 564 static const struct file_operations recent_mt_fops = {
 565         .open    = recent_seq_open,
 566         .read    = seq_read,
 567         .write   = recent_mt_proc_write,
 568         .release = seq_release_private,
 569         .owner   = THIS_MODULE,
 570         .llseek = seq_lseek,
 571 };
 572
 573 static int __net_init recent_proc_net_init(struct net *net)
 574 {
 575         struct recent_net *recent_net = recent_pernet(net);
 576
 577         recent_net->xt_recent = proc_mkdir("xt_recent", net->proc_net);
 578         if (!recent_net->xt_recent)
 579                 return -ENOMEM;
 580         return 0;
 581 }
 582
 583 static void __net_exit recent_proc_net_exit(struct net *net)
 584 {
 585         proc_net_remove(net, "xt_recent");
 586 }
 587 #else
 588 static inline int recent_proc_net_init(struct net *net)
 589 {
 590         return 0;
 591 }
 592
 593 static inline void recent_proc_net_exit(struct net *net)
 594 {
 595 }
 596 #endif /* CONFIG_PROC_FS */
 597
 598 static int __net_init recent_net_init(struct net *net)
 599 {
 600         struct recent_net *recent_net = recent_pernet(net);
 601
 602         INIT_LIST_HEAD(&recent_net->tables);
 603         return recent_proc_net_init(net);
 604 }
 605
 606 static void __net_exit recent_net_exit(struct net *net)
 607 {
 608         struct recent_net *recent_net = recent_pernet(net);
 609
 610         BUG_ON(!list_empty(&recent_net->tables));
 611         recent_proc_net_exit(net);
 612 }
 613
 614 static struct pernet_operations recent_net_ops = {
 615         .init   = recent_net_init,
 616         .exit   = recent_net_exit,
 617         .id     = &recent_net_id,
 618         .size   = sizeof(struct recent_net),
 619 };
 620
 621 static struct xt_match recent_mt_reg[] __read_mostly = {
 622         {
 623                 .name       = "recent",
 624                 .revision   = 0,
 625                 .family     = NFPROTO_IPV4,
 626                 .match      = recent_mt,
 627                 .matchsize  = sizeof(struct xt_recent_mtinfo),
 628                 .checkentry = recent_mt_check,
 629                 .destroy    = recent_mt_destroy,
 630                 .me         = THIS_MODULE,
 631         },
 632         {
 633                 .name       = "recent",
 634                 .revision   = 0,
 635                 .family     = NFPROTO_IPV6,
 636                 .match      = recent_mt,
 637                 .matchsize  = sizeof(struct xt_recent_mtinfo),
 638                 .checkentry = recent_mt_check,
 639                 .destroy    = recent_mt_destroy,
 640                 .me         = THIS_MODULE,
 641         },
 642 };
 643
 644 static int __init recent_mt_init(void)
 645 {
 646         int err;
 647
 648         if (!ip_list_tot || !ip_pkt_list_tot || ip_pkt_list_tot > 255)
 649                 return -EINVAL;
 650         ip_list_hash_size = 1 << fls(ip_list_tot);
 651
 652         err = register_pernet_subsys(&recent_net_ops);
 653         if (err)
 654                 return err;
 655         err = xt_register_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
 656         if (err)
 657                 unregister_pernet_subsys(&recent_net_ops);
 658         return err;
 659 }
 660
 661 static void __exit recent_mt_exit(void)
 662 {
 663         xt_unregister_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
 664         unregister_pernet_subsys(&recent_net_ops);
 665 }
 666
 667 module_init(recent_mt_init);
 668 module_exit(recent_mt_exit);