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