net/ipv4/netfilter/ipt_recent.c

   1 /*
   2  * Copyright (c) 2006 Patrick McHardy <kaber@trash.net>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * This is a replacement of the old ipt_recent module, which carried the
   9  * following copyright notice:
  10  *
  11  * Author: Stephen Frost <sfrost@snowman.net>
  12  * Copyright 2002-2003, Stephen Frost, 2.5.x port by laforge@netfilter.org
  13  */
  14 #include <linux/init.h>
  15 #include <linux/ip.h>
  16 #include <linux/moduleparam.h>
  17 #include <linux/proc_fs.h>
  18 #include <linux/seq_file.h>
  19 #include <linux/string.h>
  20 #include <linux/ctype.h>
  21 #include <linux/list.h>
  22 #include <linux/random.h>
  23 #include <linux/jhash.h>
  24 #include <linux/bitops.h>
  25 #include <linux/skbuff.h>
  26 #include <linux/inet.h>
  27 #include <net/net_namespace.h>
  28
  29 #include <linux/netfilter/x_tables.h>
  30 #include <linux/netfilter_ipv4/ipt_recent.h>
  31
  32 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
  33 MODULE_DESCRIPTION("Xtables: \"recently-seen\" host matching for IPv4");
  34 MODULE_LICENSE("GPL");
  35
  36 static unsigned int ip_list_tot = 100;
  37 static unsigned int ip_pkt_list_tot = 20;
  38 static unsigned int ip_list_hash_size = 0;
  39 static unsigned int ip_list_perms = 0644;
  40 static unsigned int ip_list_uid = 0;
  41 static unsigned int ip_list_gid = 0;
  42 module_param(ip_list_tot, uint, 0400);
  43 module_param(ip_pkt_list_tot, uint, 0400);
  44 module_param(ip_list_hash_size, uint, 0400);
  45 module_param(ip_list_perms, uint, 0400);
  46 module_param(ip_list_uid, uint, 0400);
  47 module_param(ip_list_gid, uint, 0400);
  48 MODULE_PARM_DESC(ip_list_tot, "number of IPs to remember per list");
  49 MODULE_PARM_DESC(ip_pkt_list_tot, "number of packets per IP to remember (max. 255)");
  50 MODULE_PARM_DESC(ip_list_hash_size, "size of hash table used to look up IPs");
  51 MODULE_PARM_DESC(ip_list_perms, "permissions on /proc/net/ipt_recent/* files");
  52 MODULE_PARM_DESC(ip_list_uid,"owner of /proc/net/ipt_recent/* files");
  53 MODULE_PARM_DESC(ip_list_gid,"owning group of /proc/net/ipt_recent/* files");
  54
  55 struct recent_entry {
  56         struct list_head        list;
  57         struct list_head        lru_list;
  58         __be32                  addr;
  59         u_int8_t                ttl;
  60         u_int8_t                index;
  61         u_int16_t               nstamps;
  62         unsigned long           stamps[0];
  63 };
  64
  65 struct recent_table {
  66         struct list_head        list;
  67         char                    name[IPT_RECENT_NAME_LEN];
  68 #ifdef CONFIG_PROC_FS
  69         struct proc_dir_entry   *proc;
  70 #endif
  71         unsigned int            refcnt;
  72         unsigned int            entries;
  73         struct list_head        lru_list;
  74         struct list_head        iphash[0];
  75 };
  76
  77 static LIST_HEAD(tables);
  78 static DEFINE_SPINLOCK(recent_lock);
  79 static DEFINE_MUTEX(recent_mutex);
  80
  81 #ifdef CONFIG_PROC_FS
  82 static struct proc_dir_entry    *proc_dir;
  83 static const struct file_operations     recent_fops;
  84 #endif
  85
  86 static u_int32_t hash_rnd;
  87 static int hash_rnd_initted;
  88
  89 static unsigned int recent_entry_hash(__be32 addr)
  90 {
  91         if (!hash_rnd_initted) {
  92                 get_random_bytes(&hash_rnd, 4);
  93                 hash_rnd_initted = 1;
  94         }
  95         return jhash_1word((__force u32)addr, hash_rnd) & (ip_list_hash_size - 1);
  96 }
  97
  98 static struct recent_entry *
  99 recent_entry_lookup(const struct recent_table *table, __be32 addr, u_int8_t ttl)
 100 {
 101         struct recent_entry *e;
 102         unsigned int h;
 103
 104         h = recent_entry_hash(addr);
 105         list_for_each_entry(e, &table->iphash[h], list)
 106                 if (e->addr == addr && (ttl == e->ttl || !ttl || !e->ttl))
 107                         return e;
 108         return NULL;
 109 }
 110
 111 static void recent_entry_remove(struct recent_table *t, struct recent_entry *e)
 112 {
 113         list_del(&e->list);
 114         list_del(&e->lru_list);
 115         kfree(e);
 116         t->entries--;
 117 }
 118
 119 static struct recent_entry *
 120 recent_entry_init(struct recent_table *t, __be32 addr, u_int8_t ttl)
 121 {
 122         struct recent_entry *e;
 123
 124         if (t->entries >= ip_list_tot) {
 125                 e = list_entry(t->lru_list.next, struct recent_entry, lru_list);
 126                 recent_entry_remove(t, e);
 127         }
 128         e = kmalloc(sizeof(*e) + sizeof(e->stamps[0]) * ip_pkt_list_tot,
 129                     GFP_ATOMIC);
 130         if (e == NULL)
 131                 return NULL;
 132         e->addr      = addr;
 133         e->ttl       = ttl;
 134         e->stamps[0] = jiffies;
 135         e->nstamps   = 1;
 136         e->index     = 1;
 137         list_add_tail(&e->list, &t->iphash[recent_entry_hash(addr)]);
 138         list_add_tail(&e->lru_list, &t->lru_list);
 139         t->entries++;
 140         return e;
 141 }
 142
 143 static void recent_entry_update(struct recent_table *t, struct recent_entry *e)
 144 {
 145         e->stamps[e->index++] = jiffies;
 146         if (e->index > e->nstamps)
 147                 e->nstamps = e->index;
 148         e->index %= ip_pkt_list_tot;
 149         list_move_tail(&e->lru_list, &t->lru_list);
 150 }
 151
 152 static struct recent_table *recent_table_lookup(const char *name)
 153 {
 154         struct recent_table *t;
 155
 156         list_for_each_entry(t, &tables, list)
 157                 if (!strcmp(t->name, name))
 158                         return t;
 159         return NULL;
 160 }
 161
 162 static void recent_table_flush(struct recent_table *t)
 163 {
 164         struct recent_entry *e, *next;
 165         unsigned int i;
 166
 167         for (i = 0; i < ip_list_hash_size; i++)
 168                 list_for_each_entry_safe(e, next, &t->iphash[i], list)
 169                         recent_entry_remove(t, e);
 170 }
 171
 172 static bool
 173 recent_mt(const struct sk_buff *skb, const struct net_device *in,
 174           const struct net_device *out, const struct xt_match *match,
 175           const void *matchinfo, int offset, unsigned int protoff,
 176           bool *hotdrop)
 177 {
 178         const struct ipt_recent_info *info = matchinfo;
 179         struct recent_table *t;
 180         struct recent_entry *e;
 181         __be32 addr;
 182         u_int8_t ttl;
 183         bool ret = info->invert;
 184
 185         if (info->side == IPT_RECENT_DEST)
 186                 addr = ip_hdr(skb)->daddr;
 187         else
 188                 addr = ip_hdr(skb)->saddr;
 189
 190         ttl = ip_hdr(skb)->ttl;
 191         /* use TTL as seen before forwarding */
 192         if (out && !skb->sk)
 193                 ttl++;
 194
 195         spin_lock_bh(&recent_lock);
 196         t = recent_table_lookup(info->name);
 197         e = recent_entry_lookup(t, addr,
 198                                 info->check_set & IPT_RECENT_TTL ? ttl : 0);
 199         if (e == NULL) {
 200                 if (!(info->check_set & IPT_RECENT_SET))
 201                         goto out;
 202                 e = recent_entry_init(t, addr, ttl);
 203                 if (e == NULL)
 204                         *hotdrop = true;
 205                 ret = !ret;
 206                 goto out;
 207         }
 208
 209         if (info->check_set & IPT_RECENT_SET)
 210                 ret = !ret;
 211         else if (info->check_set & IPT_RECENT_REMOVE) {
 212                 recent_entry_remove(t, e);
 213                 ret = !ret;
 214         } else if (info->check_set & (IPT_RECENT_CHECK | IPT_RECENT_UPDATE)) {
 215                 unsigned long time = jiffies - info->seconds * HZ;
 216                 unsigned int i, hits = 0;
 217
 218                 for (i = 0; i < e->nstamps; i++) {
 219                         if (info->seconds && time_after(time, e->stamps[i]))
 220                                 continue;
 221                         if (++hits >= info->hit_count) {
 222                                 ret = !ret;
 223                                 break;
 224                         }
 225                 }
 226         }
 227
 228         if (info->check_set & IPT_RECENT_SET ||
 229             (info->check_set & IPT_RECENT_UPDATE && ret)) {
 230                 recent_entry_update(t, e);
 231                 e->ttl = ttl;
 232         }
 233 out:
 234         spin_unlock_bh(&recent_lock);
 235         return ret;
 236 }
 237
 238 static bool
 239 recent_mt_check(const char *tablename, const void *ip,
 240                 const struct xt_match *match, void *matchinfo,
 241                 unsigned int hook_mask)
 242 {
 243         const struct ipt_recent_info *info = matchinfo;
 244         struct recent_table *t;
 245         unsigned i;
 246         bool ret = false;
 247
 248         if (hweight8(info->check_set &
 249                      (IPT_RECENT_SET | IPT_RECENT_REMOVE |
 250                       IPT_RECENT_CHECK | IPT_RECENT_UPDATE)) != 1)
 251                 return false;
 252         if ((info->check_set & (IPT_RECENT_SET | IPT_RECENT_REMOVE)) &&
 253             (info->seconds || info->hit_count))
 254                 return false;
 255         if (info->hit_count > ip_pkt_list_tot)
 256                 return false;
 257         if (info->name[0] == '\0' ||
 258             strnlen(info->name, IPT_RECENT_NAME_LEN) == IPT_RECENT_NAME_LEN)
 259                 return false;
 260
 261         mutex_lock(&recent_mutex);
 262         t = recent_table_lookup(info->name);
 263         if (t != NULL) {
 264                 t->refcnt++;
 265                 ret = true;
 266                 goto out;
 267         }
 268
 269         t = kzalloc(sizeof(*t) + sizeof(t->iphash[0]) * ip_list_hash_size,
 270                     GFP_KERNEL);
 271         if (t == NULL)
 272                 goto out;
 273         t->refcnt = 1;
 274         strcpy(t->name, info->name);
 275         INIT_LIST_HEAD(&t->lru_list);
 276         for (i = 0; i < ip_list_hash_size; i++)
 277                 INIT_LIST_HEAD(&t->iphash[i]);
 278 #ifdef CONFIG_PROC_FS
 279         t->proc = proc_create(t->name, ip_list_perms, proc_dir, &recent_fops);
 280         if (t->proc == NULL) {
 281                 kfree(t);
 282                 goto out;
 283         }
 284         t->proc->uid       = ip_list_uid;
 285         t->proc->gid       = ip_list_gid;
 286         t->proc->data      = t;
 287 #endif
 288         spin_lock_bh(&recent_lock);
 289         list_add_tail(&t->list, &tables);
 290         spin_unlock_bh(&recent_lock);
 291         ret = true;
 292 out:
 293         mutex_unlock(&recent_mutex);
 294         return ret;
 295 }
 296
 297 static void recent_mt_destroy(const struct xt_match *match, void *matchinfo)
 298 {
 299         const struct ipt_recent_info *info = matchinfo;
 300         struct recent_table *t;
 301
 302         mutex_lock(&recent_mutex);
 303         t = recent_table_lookup(info->name);
 304         if (--t->refcnt == 0) {
 305                 spin_lock_bh(&recent_lock);
 306                 list_del(&t->list);
 307                 spin_unlock_bh(&recent_lock);
 308                 recent_table_flush(t);
 309 #ifdef CONFIG_PROC_FS
 310                 remove_proc_entry(t->name, proc_dir);
 311 #endif
 312                 kfree(t);
 313         }
 314         mutex_unlock(&recent_mutex);
 315 }
 316
 317 #ifdef CONFIG_PROC_FS
 318 struct recent_iter_state {
 319         struct recent_table     *table;
 320         unsigned int            bucket;
 321 };
 322
 323 static void *recent_seq_start(struct seq_file *seq, loff_t *pos)
 324         __acquires(recent_lock)
 325 {
 326         struct recent_iter_state *st = seq->private;
 327         const struct recent_table *t = st->table;
 328         struct recent_entry *e;
 329         loff_t p = *pos;
 330
 331         spin_lock_bh(&recent_lock);
 332
 333         for (st->bucket = 0; st->bucket < ip_list_hash_size; st->bucket++)
 334                 list_for_each_entry(e, &t->iphash[st->bucket], list)
 335                         if (p-- == 0)
 336                                 return e;
 337         return NULL;
 338 }
 339
 340 static void *recent_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 341 {
 342         struct recent_iter_state *st = seq->private;
 343         struct recent_table *t = st->table;
 344         struct recent_entry *e = v;
 345         struct list_head *head = e->list.next;
 346
 347         while (head == &t->iphash[st->bucket]) {
 348                 if (++st->bucket >= ip_list_hash_size)
 349                         return NULL;
 350                 head = t->iphash[st->bucket].next;
 351         }
 352         (*pos)++;
 353         return list_entry(head, struct recent_entry, list);
 354 }
 355
 356 static void recent_seq_stop(struct seq_file *s, void *v)
 357         __releases(recent_lock)
 358 {
 359         spin_unlock_bh(&recent_lock);
 360 }
 361
 362 static int recent_seq_show(struct seq_file *seq, void *v)
 363 {
 364         struct recent_entry *e = v;
 365         unsigned int i;
 366
 367         i = (e->index - 1) % ip_pkt_list_tot;
 368         seq_printf(seq, "src=%u.%u.%u.%u ttl: %u last_seen: %lu oldest_pkt: %u",
 369                    NIPQUAD(e->addr), e->ttl, e->stamps[i], e->index);
 370         for (i = 0; i < e->nstamps; i++)
 371                 seq_printf(seq, "%s %lu", i ? "," : "", e->stamps[i]);
 372         seq_printf(seq, "\n");
 373         return 0;
 374 }
 375
 376 static const struct seq_operations recent_seq_ops = {
 377         .start          = recent_seq_start,
 378         .next           = recent_seq_next,
 379         .stop           = recent_seq_stop,
 380         .show           = recent_seq_show,
 381 };
 382
 383 static int recent_seq_open(struct inode *inode, struct file *file)
 384 {
 385         struct proc_dir_entry *pde = PDE(inode);
 386         struct recent_iter_state *st;
 387
 388         st = __seq_open_private(file, &recent_seq_ops, sizeof(*st));
 389         if (st == NULL)
 390                 return -ENOMEM;
 391
 392         st->table    = pde->data;
 393         return 0;
 394 }
 395
 396 static ssize_t recent_proc_write(struct file *file, const char __user *input,
 397                                  size_t size, loff_t *loff)
 398 {
 399         struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
 400         struct recent_table *t = pde->data;
 401         struct recent_entry *e;
 402         char buf[sizeof("+255.255.255.255")], *c = buf;
 403         __be32 addr;
 404         int add;
 405
 406         if (size > sizeof(buf))
 407                 size = sizeof(buf);
 408         if (copy_from_user(buf, input, size))
 409                 return -EFAULT;
 410         while (isspace(*c))
 411                 c++;
 412
 413         if (size - (c - buf) < 5)
 414                 return c - buf;
 415         if (!strncmp(c, "clear", 5)) {
 416                 c += 5;
 417                 spin_lock_bh(&recent_lock);
 418                 recent_table_flush(t);
 419                 spin_unlock_bh(&recent_lock);
 420                 return c - buf;
 421         }
 422
 423         switch (*c) {
 424         case '-':
 425                 add = 0;
 426                 c++;
 427                 break;
 428         case '+':
 429                 c++;
 430         default:
 431                 add = 1;
 432                 break;
 433         }
 434         addr = in_aton(c);
 435
 436         spin_lock_bh(&recent_lock);
 437         e = recent_entry_lookup(t, addr, 0);
 438         if (e == NULL) {
 439                 if (add)
 440                         recent_entry_init(t, addr, 0);
 441         } else {
 442                 if (add)
 443                         recent_entry_update(t, e);
 444                 else
 445                         recent_entry_remove(t, e);
 446         }
 447         spin_unlock_bh(&recent_lock);
 448         return size;
 449 }
 450
 451 static const struct file_operations recent_fops = {
 452         .open           = recent_seq_open,
 453         .read           = seq_read,
 454         .write          = recent_proc_write,
 455         .release        = seq_release_private,
 456         .owner          = THIS_MODULE,
 457 };
 458 #endif /* CONFIG_PROC_FS */
 459
 460 static struct xt_match recent_mt_reg __read_mostly = {
 461         .name           = "recent",
 462         .family         = AF_INET,
 463         .match          = recent_mt,
 464         .matchsize      = sizeof(struct ipt_recent_info),
 465         .checkentry     = recent_mt_check,
 466         .destroy        = recent_mt_destroy,
 467         .me             = THIS_MODULE,
 468 };
 469
 470 static int __init recent_mt_init(void)
 471 {
 472         int err;
 473
 474         if (!ip_list_tot || !ip_pkt_list_tot || ip_pkt_list_tot > 255)
 475                 return -EINVAL;
 476         ip_list_hash_size = 1 << fls(ip_list_tot);
 477
 478         err = xt_register_match(&recent_mt_reg);
 479 #ifdef CONFIG_PROC_FS
 480         if (err)
 481                 return err;
 482         proc_dir = proc_mkdir("ipt_recent", init_net.proc_net);
 483         if (proc_dir == NULL) {
 484                 xt_unregister_match(&recent_mt_reg);
 485                 err = -ENOMEM;
 486         }
 487 #endif
 488         return err;
 489 }
 490
 491 static void __exit recent_mt_exit(void)
 492 {
 493         BUG_ON(!list_empty(&tables));
 494         xt_unregister_match(&recent_mt_reg);
 495 #ifdef CONFIG_PROC_FS
 496         remove_proc_entry("ipt_recent", init_net.proc_net);
 497 #endif
 498 }
 499
 500 module_init(recent_mt_init);
 501 module_exit(recent_mt_exit);