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
  28 #include <linux/netfilter/x_tables.h>
  29 #include <linux/netfilter_ipv4/ipt_recent.h>
  30
  31 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
  32 MODULE_DESCRIPTION("IP tables recently seen matching module");
  33 MODULE_LICENSE("GPL");
  34
  35 static unsigned int ip_list_tot = 100;
  36 static unsigned int ip_pkt_list_tot = 20;
  37 static unsigned int ip_list_hash_size = 0;
  38 static unsigned int ip_list_perms = 0644;
  39 static unsigned int ip_list_uid = 0;
  40 static unsigned int ip_list_gid = 0;
  41 module_param(ip_list_tot, uint, 0400);
  42 module_param(ip_pkt_list_tot, uint, 0400);
  43 module_param(ip_list_hash_size, uint, 0400);
  44 module_param(ip_list_perms, uint, 0400);
  45 module_param(ip_list_uid, uint, 0400);
  46 module_param(ip_list_gid, uint, 0400);
  47 MODULE_PARM_DESC(ip_list_tot, "number of IPs to remember per list");
  48 MODULE_PARM_DESC(ip_pkt_list_tot, "number of packets per IP to remember (max. 255)");
  49 MODULE_PARM_DESC(ip_list_hash_size, "size of hash table used to look up IPs");
  50 MODULE_PARM_DESC(ip_list_perms, "permissions on /proc/net/ipt_recent/* files");
  51 MODULE_PARM_DESC(ip_list_uid,"owner of /proc/net/ipt_recent/* files");
  52 MODULE_PARM_DESC(ip_list_gid,"owning group of /proc/net/ipt_recent/* files");
  53
  54 struct recent_entry {
  55         struct list_head        list;
  56         struct list_head        lru_list;
  57         __be32                  addr;
  58         u_int8_t                ttl;
  59         u_int8_t                index;
  60         u_int16_t               nstamps;
  61         unsigned long           stamps[0];
  62 };
  63
  64 struct recent_table {
  65         struct list_head        list;
  66         char                    name[IPT_RECENT_NAME_LEN];
  67 #ifdef CONFIG_PROC_FS
  68         struct proc_dir_entry   *proc;
  69 #endif
  70         unsigned int            refcnt;
  71         unsigned int            entries;
  72         struct list_head        lru_list;
  73         struct list_head        iphash[0];
  74 };
  75
  76 static LIST_HEAD(tables);
  77 static DEFINE_SPINLOCK(recent_lock);
  78 static DEFINE_MUTEX(recent_mutex);
  79
  80 #ifdef CONFIG_PROC_FS
  81 static struct proc_dir_entry    *proc_dir;
  82 static const struct file_operations     recent_fops;
  83 #endif
  84
  85 static u_int32_t hash_rnd;
  86 static int hash_rnd_initted;
  87
  88 static unsigned int recent_entry_hash(__be32 addr)
  89 {
  90         if (!hash_rnd_initted) {
  91                 get_random_bytes(&hash_rnd, 4);
  92                 hash_rnd_initted = 1;
  93         }
  94         return jhash_1word((__force u32)addr, hash_rnd) & (ip_list_hash_size - 1);
  95 }
  96
  97 static struct recent_entry *
  98 recent_entry_lookup(const struct recent_table *table, __be32 addr, u_int8_t ttl)
  99 {
 100         struct recent_entry *e;
 101         unsigned int h;
 102
 103         h = recent_entry_hash(addr);
 104         list_for_each_entry(e, &table->iphash[h], list)
 105                 if (e->addr == addr && (ttl == e->ttl || !ttl || !e->ttl))
 106                         return e;
 107         return NULL;
 108 }
 109
 110 static void recent_entry_remove(struct recent_table *t, struct recent_entry *e)
 111 {
 112         list_del(&e->list);
 113         list_del(&e->lru_list);
 114         kfree(e);
 115         t->entries--;
 116 }
 117
 118 static struct recent_entry *
 119 recent_entry_init(struct recent_table *t, __be32 addr, u_int8_t ttl)
 120 {
 121         struct recent_entry *e;
 122
 123         if (t->entries >= ip_list_tot) {
 124                 e = list_entry(t->lru_list.next, struct recent_entry, lru_list);
 125                 recent_entry_remove(t, e);
 126         }
 127         e = kmalloc(sizeof(*e) + sizeof(e->stamps[0]) * ip_pkt_list_tot,
 128                     GFP_ATOMIC);
 129         if (e == NULL)
 130                 return NULL;
 131         e->addr      = addr;
 132         e->ttl       = ttl;
 133         e->stamps[0] = jiffies;
 134         e->nstamps   = 1;
 135         e->index     = 1;
 136         list_add_tail(&e->list, &t->iphash[recent_entry_hash(addr)]);
 137         list_add_tail(&e->lru_list, &t->lru_list);
 138         t->entries++;
 139         return e;
 140 }
 141
 142 static void recent_entry_update(struct recent_table *t, struct recent_entry *e)
 143 {
 144         e->stamps[e->index++] = jiffies;
 145         if (e->index > e->nstamps)
 146                 e->nstamps = e->index;
 147         e->index %= ip_pkt_list_tot;
 148         list_move_tail(&e->lru_list, &t->lru_list);
 149 }
 150
 151 static struct recent_table *recent_table_lookup(const char *name)
 152 {
 153         struct recent_table *t;
 154
 155         list_for_each_entry(t, &tables, list)
 156                 if (!strcmp(t->name, name))
 157                         return t;
 158         return NULL;
 159 }
 160
 161 static void recent_table_flush(struct recent_table *t)
 162 {
 163         struct recent_entry *e, *next;
 164         unsigned int i;
 165
 166         for (i = 0; i < ip_list_hash_size; i++) {
 167                 list_for_each_entry_safe(e, next, &t->iphash[i], list)
 168                         recent_entry_remove(t, e);
 169         }
 170 }
 171
 172 static int
 173 ipt_recent_match(const struct sk_buff *skb,
 174                  const struct net_device *in, const struct net_device *out,
 175                  const struct xt_match *match, const void *matchinfo,
 176                  int offset, unsigned int protoff, int *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         int 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 = 1;
 205                 ret ^= 1;
 206                 goto out;
 207         }
 208
 209         if (info->check_set & IPT_RECENT_SET)
 210                 ret ^= 1;
 211         else if (info->check_set & IPT_RECENT_REMOVE) {
 212                 recent_entry_remove(t, e);
 213                 ret ^= 1;
 214         } else if (info->check_set & (IPT_RECENT_CHECK | IPT_RECENT_UPDATE)) {
 215                 unsigned long t = 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(t, e->stamps[i]))
 220                                 continue;
 221                         if (++hits >= info->hit_count) {
 222                                 ret ^= 1;
 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 int
 239 ipt_recent_checkentry(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         int ret = 0;
 247
 248         if (hweight8(info->check_set &
 249                      (IPT_RECENT_SET | IPT_RECENT_REMOVE |
 250                       IPT_RECENT_CHECK | IPT_RECENT_UPDATE)) != 1)
 251                 return 0;
 252         if ((info->check_set & (IPT_RECENT_SET | IPT_RECENT_REMOVE)) &&
 253             (info->seconds || info->hit_count))
 254                 return 0;
 255         if (info->name[0] == '\0' ||
 256             strnlen(info->name, IPT_RECENT_NAME_LEN) == IPT_RECENT_NAME_LEN)
 257                 return 0;
 258
 259         mutex_lock(&recent_mutex);
 260         t = recent_table_lookup(info->name);
 261         if (t != NULL) {
 262                 t->refcnt++;
 263                 ret = 1;
 264                 goto out;
 265         }
 266
 267         t = kzalloc(sizeof(*t) + sizeof(t->iphash[0]) * ip_list_hash_size,
 268                     GFP_KERNEL);
 269         if (t == NULL)
 270                 goto out;
 271         t->refcnt = 1;
 272         strcpy(t->name, info->name);
 273         INIT_LIST_HEAD(&t->lru_list);
 274         for (i = 0; i < ip_list_hash_size; i++)
 275                 INIT_LIST_HEAD(&t->iphash[i]);
 276 #ifdef CONFIG_PROC_FS
 277         t->proc = create_proc_entry(t->name, ip_list_perms, proc_dir);
 278         if (t->proc == NULL) {
 279                 kfree(t);
 280                 goto out;
 281         }
 282         t->proc->proc_fops = &recent_fops;
 283         t->proc->uid       = ip_list_uid;
 284         t->proc->gid       = ip_list_gid;
 285         t->proc->data      = t;
 286 #endif
 287         spin_lock_bh(&recent_lock);
 288         list_add_tail(&t->list, &tables);
 289         spin_unlock_bh(&recent_lock);
 290         ret = 1;
 291 out:
 292         mutex_unlock(&recent_mutex);
 293         return ret;
 294 }
 295
 296 static void
 297 ipt_recent_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 {
 325         struct recent_iter_state *st = seq->private;
 326         struct recent_table *t = st->table;
 327         struct recent_entry *e;
 328         loff_t p = *pos;
 329
 330         spin_lock_bh(&recent_lock);
 331
 332         for (st->bucket = 0; st->bucket < ip_list_hash_size; st->bucket++) {
 333                 list_for_each_entry(e, &t->iphash[st->bucket], list) {
 334                         if (p-- == 0)
 335                                 return e;
 336                 }
 337         }
 338         return NULL;
 339 }
 340
 341 static void *recent_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 342 {
 343         struct recent_iter_state *st = seq->private;
 344         struct recent_table *t = st->table;
 345         struct recent_entry *e = v;
 346         struct list_head *head = e->list.next;
 347
 348         while (head == &t->iphash[st->bucket]) {
 349                 if (++st->bucket >= ip_list_hash_size)
 350                         return NULL;
 351                 head = t->iphash[st->bucket].next;
 352         }
 353         (*pos)++;
 354         return list_entry(head, struct recent_entry, list);
 355 }
 356
 357 static void recent_seq_stop(struct seq_file *s, void *v)
 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 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 seq_file *seq;
 387         struct recent_iter_state *st;
 388         int ret;
 389
 390         st = kzalloc(sizeof(*st), GFP_KERNEL);
 391         if (st == NULL)
 392                 return -ENOMEM;
 393         ret = seq_open(file, &recent_seq_ops);
 394         if (ret)
 395                 kfree(st);
 396         st->table    = pde->data;
 397         seq          = file->private_data;
 398         seq->private = st;
 399         return ret;
 400 }
 401
 402 static ssize_t recent_proc_write(struct file *file, const char __user *input,
 403                                  size_t size, loff_t *loff)
 404 {
 405         struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
 406         struct recent_table *t = pde->data;
 407         struct recent_entry *e;
 408         char buf[sizeof("+255.255.255.255")], *c = buf;
 409         __be32 addr;
 410         int add;
 411
 412         if (size > sizeof(buf))
 413                 size = sizeof(buf);
 414         if (copy_from_user(buf, input, size))
 415                 return -EFAULT;
 416         while (isspace(*c))
 417                 c++;
 418
 419         if (size - (c - buf) < 5)
 420                 return c - buf;
 421         if (!strncmp(c, "clear", 5)) {
 422                 c += 5;
 423                 spin_lock_bh(&recent_lock);
 424                 recent_table_flush(t);
 425                 spin_unlock_bh(&recent_lock);
 426                 return c - buf;
 427         }
 428
 429         switch (*c) {
 430         case '-':
 431                 add = 0;
 432                 c++;
 433                 break;
 434         case '+':
 435                 c++;
 436         default:
 437                 add = 1;
 438                 break;
 439         }
 440         addr = in_aton(c);
 441
 442         spin_lock_bh(&recent_lock);
 443         e = recent_entry_lookup(t, addr, 0);
 444         if (e == NULL) {
 445                 if (add)
 446                         recent_entry_init(t, addr, 0);
 447         } else {
 448                 if (add)
 449                         recent_entry_update(t, e);
 450                 else
 451                         recent_entry_remove(t, e);
 452         }
 453         spin_unlock_bh(&recent_lock);
 454         return size;
 455 }
 456
 457 static const struct file_operations recent_fops = {
 458         .open           = recent_seq_open,
 459         .read           = seq_read,
 460         .write          = recent_proc_write,
 461         .release        = seq_release_private,
 462         .owner          = THIS_MODULE,
 463 };
 464 #endif /* CONFIG_PROC_FS */
 465
 466 static struct xt_match recent_match = {
 467         .name           = "recent",
 468         .family         = AF_INET,
 469         .match          = ipt_recent_match,
 470         .matchsize      = sizeof(struct ipt_recent_info),
 471         .checkentry     = ipt_recent_checkentry,
 472         .destroy        = ipt_recent_destroy,
 473         .me             = THIS_MODULE,
 474 };
 475
 476 static int __init ipt_recent_init(void)
 477 {
 478         int err;
 479
 480         if (!ip_list_tot || !ip_pkt_list_tot || ip_pkt_list_tot > 255)
 481                 return -EINVAL;
 482         ip_list_hash_size = 1 << fls(ip_list_tot);
 483
 484         err = xt_register_match(&recent_match);
 485 #ifdef CONFIG_PROC_FS
 486         if (err)
 487                 return err;
 488         proc_dir = proc_mkdir("ipt_recent", proc_net);
 489         if (proc_dir == NULL) {
 490                 xt_unregister_match(&recent_match);
 491                 err = -ENOMEM;
 492         }
 493 #endif
 494         return err;
 495 }
 496
 497 static void __exit ipt_recent_exit(void)
 498 {
 499         BUG_ON(!list_empty(&tables));
 500         xt_unregister_match(&recent_match);
 501 #ifdef CONFIG_PROC_FS
 502         remove_proc_entry("ipt_recent", proc_net);
 503 #endif
 504 }
 505
 506 module_init(ipt_recent_init);
 507 module_exit(ipt_recent_exit);