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 static bool
 172 ipt_recent_match(const struct sk_buff *skb,
 173                  const struct net_device *in, const struct net_device *out,
 174                  const struct xt_match *match, const void *matchinfo,
 175                  int offset, unsigned int protoff, bool *hotdrop)
 176 {
 177         const struct ipt_recent_info *info = matchinfo;
 178         struct recent_table *t;
 179         struct recent_entry *e;
 180         __be32 addr;
 181         u_int8_t ttl;
 182         bool ret = info->invert;
 183
 184         if (info->side == IPT_RECENT_DEST)
 185                 addr = ip_hdr(skb)->daddr;
 186         else
 187                 addr = ip_hdr(skb)->saddr;
 188
 189         ttl = ip_hdr(skb)->ttl;
 190         /* use TTL as seen before forwarding */
 191         if (out && !skb->sk)
 192                 ttl++;
 193
 194         spin_lock_bh(&recent_lock);
 195         t = recent_table_lookup(info->name);
 196         e = recent_entry_lookup(t, addr,
 197                                 info->check_set & IPT_RECENT_TTL ? ttl : 0);
 198         if (e == NULL) {
 199                 if (!(info->check_set & IPT_RECENT_SET))
 200                         goto out;
 201                 e = recent_entry_init(t, addr, ttl);
 202                 if (e == NULL)
 203                         *hotdrop = true;
 204                 ret = !ret;
 205                 goto out;
 206         }
 207
 208         if (info->check_set & IPT_RECENT_SET)
 209                 ret = !ret;
 210         else if (info->check_set & IPT_RECENT_REMOVE) {
 211                 recent_entry_remove(t, e);
 212                 ret = !ret;
 213         } else if (info->check_set & (IPT_RECENT_CHECK | IPT_RECENT_UPDATE)) {
 214                 unsigned long t = jiffies - info->seconds * HZ;
 215                 unsigned int i, hits = 0;
 216
 217                 for (i = 0; i < e->nstamps; i++) {
 218                         if (info->seconds && time_after(t, e->stamps[i]))
 219                                 continue;
 220                         if (++hits >= info->hit_count) {
 221                                 ret = !ret;
 222                                 break;
 223                         }
 224                 }
 225         }
 226
 227         if (info->check_set & IPT_RECENT_SET ||
 228             (info->check_set & IPT_RECENT_UPDATE && ret)) {
 229                 recent_entry_update(t, e);
 230                 e->ttl = ttl;
 231         }
 232 out:
 233         spin_unlock_bh(&recent_lock);
 234         return ret;
 235 }
 236
 237 static bool
 238 ipt_recent_checkentry(const char *tablename, const void *ip,
 239                       const struct xt_match *match, void *matchinfo,
 240                       unsigned int hook_mask)
 241 {
 242         const struct ipt_recent_info *info = matchinfo;
 243         struct recent_table *t;
 244         unsigned i;
 245         bool ret = false;
 246
 247         if (hweight8(info->check_set &
 248                      (IPT_RECENT_SET | IPT_RECENT_REMOVE |
 249                       IPT_RECENT_CHECK | IPT_RECENT_UPDATE)) != 1)
 250                 return false;
 251         if ((info->check_set & (IPT_RECENT_SET | IPT_RECENT_REMOVE)) &&
 252             (info->seconds || info->hit_count))
 253                 return false;
 254         if (info->name[0] == '\0' ||
 255             strnlen(info->name, IPT_RECENT_NAME_LEN) == IPT_RECENT_NAME_LEN)
 256                 return false;
 257
 258         mutex_lock(&recent_mutex);
 259         t = recent_table_lookup(info->name);
 260         if (t != NULL) {
 261                 t->refcnt++;
 262                 ret = true;
 263                 goto out;
 264         }
 265
 266         t = kzalloc(sizeof(*t) + sizeof(t->iphash[0]) * ip_list_hash_size,
 267                     GFP_KERNEL);
 268         if (t == NULL)
 269                 goto out;
 270         t->refcnt = 1;
 271         strcpy(t->name, info->name);
 272         INIT_LIST_HEAD(&t->lru_list);
 273         for (i = 0; i < ip_list_hash_size; i++)
 274                 INIT_LIST_HEAD(&t->iphash[i]);
 275 #ifdef CONFIG_PROC_FS
 276         t->proc = create_proc_entry(t->name, ip_list_perms, proc_dir);
 277         if (t->proc == NULL) {
 278                 kfree(t);
 279                 goto out;
 280         }
 281         t->proc->proc_fops = &recent_fops;
 282         t->proc->uid       = ip_list_uid;
 283         t->proc->gid       = ip_list_gid;
 284         t->proc->data      = t;
 285 #endif
 286         spin_lock_bh(&recent_lock);
 287         list_add_tail(&t->list, &tables);
 288         spin_unlock_bh(&recent_lock);
 289         ret = true;
 290 out:
 291         mutex_unlock(&recent_mutex);
 292         return ret;
 293 }
 294
 295 static void
 296 ipt_recent_destroy(const struct xt_match *match, void *matchinfo)
 297 {
 298         const struct ipt_recent_info *info = matchinfo;
 299         struct recent_table *t;
 300
 301         mutex_lock(&recent_mutex);
 302         t = recent_table_lookup(info->name);
 303         if (--t->refcnt == 0) {
 304                 spin_lock_bh(&recent_lock);
 305                 list_del(&t->list);
 306                 spin_unlock_bh(&recent_lock);
 307                 recent_table_flush(t);
 308 #ifdef CONFIG_PROC_FS
 309                 remove_proc_entry(t->name, proc_dir);
 310 #endif
 311                 kfree(t);
 312         }
 313         mutex_unlock(&recent_mutex);
 314 }
 315
 316 #ifdef CONFIG_PROC_FS
 317 struct recent_iter_state {
 318         struct recent_table     *table;
 319         unsigned int            bucket;
 320 };
 321
 322 static void *recent_seq_start(struct seq_file *seq, loff_t *pos)
 323 {
 324         struct recent_iter_state *st = seq->private;
 325         const struct recent_table *t = st->table;
 326         struct recent_entry *e;
 327         loff_t p = *pos;
 328
 329         spin_lock_bh(&recent_lock);
 330
 331         for (st->bucket = 0; st->bucket < ip_list_hash_size; st->bucket++)
 332                 list_for_each_entry(e, &t->iphash[st->bucket], list)
 333                         if (p-- == 0)
 334                                 return e;
 335         return NULL;
 336 }
 337
 338 static void *recent_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 339 {
 340         struct recent_iter_state *st = seq->private;
 341         struct recent_table *t = st->table;
 342         struct recent_entry *e = v;
 343         struct list_head *head = e->list.next;
 344
 345         while (head == &t->iphash[st->bucket]) {
 346                 if (++st->bucket >= ip_list_hash_size)
 347                         return NULL;
 348                 head = t->iphash[st->bucket].next;
 349         }
 350         (*pos)++;
 351         return list_entry(head, struct recent_entry, list);
 352 }
 353
 354 static void recent_seq_stop(struct seq_file *s, void *v)
 355 {
 356         spin_unlock_bh(&recent_lock);
 357 }
 358
 359 static int recent_seq_show(struct seq_file *seq, void *v)
 360 {
 361         struct recent_entry *e = v;
 362         unsigned int i;
 363
 364         i = (e->index - 1) % ip_pkt_list_tot;
 365         seq_printf(seq, "src=%u.%u.%u.%u ttl: %u last_seen: %lu oldest_pkt: %u",
 366                    NIPQUAD(e->addr), e->ttl, e->stamps[i], e->index);
 367         for (i = 0; i < e->nstamps; i++)
 368                 seq_printf(seq, "%s %lu", i ? "," : "", e->stamps[i]);
 369         seq_printf(seq, "\n");
 370         return 0;
 371 }
 372
 373 static const struct seq_operations recent_seq_ops = {
 374         .start          = recent_seq_start,
 375         .next           = recent_seq_next,
 376         .stop           = recent_seq_stop,
 377         .show           = recent_seq_show,
 378 };
 379
 380 static int recent_seq_open(struct inode *inode, struct file *file)
 381 {
 382         struct proc_dir_entry *pde = PDE(inode);
 383         struct seq_file *seq;
 384         struct recent_iter_state *st;
 385         int ret;
 386
 387         st = kzalloc(sizeof(*st), GFP_KERNEL);
 388         if (st == NULL)
 389                 return -ENOMEM;
 390         ret = seq_open(file, &recent_seq_ops);
 391         if (ret)
 392                 kfree(st);
 393         st->table    = pde->data;
 394         seq          = file->private_data;
 395         seq->private = st;
 396         return ret;
 397 }
 398
 399 static ssize_t recent_proc_write(struct file *file, const char __user *input,
 400                                  size_t size, loff_t *loff)
 401 {
 402         struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
 403         struct recent_table *t = pde->data;
 404         struct recent_entry *e;
 405         char buf[sizeof("+255.255.255.255")], *c = buf;
 406         __be32 addr;
 407         int add;
 408
 409         if (size > sizeof(buf))
 410                 size = sizeof(buf);
 411         if (copy_from_user(buf, input, size))
 412                 return -EFAULT;
 413         while (isspace(*c))
 414                 c++;
 415
 416         if (size - (c - buf) < 5)
 417                 return c - buf;
 418         if (!strncmp(c, "clear", 5)) {
 419                 c += 5;
 420                 spin_lock_bh(&recent_lock);
 421                 recent_table_flush(t);
 422                 spin_unlock_bh(&recent_lock);
 423                 return c - buf;
 424         }
 425
 426         switch (*c) {
 427         case '-':
 428                 add = 0;
 429                 c++;
 430                 break;
 431         case '+':
 432                 c++;
 433         default:
 434                 add = 1;
 435                 break;
 436         }
 437         addr = in_aton(c);
 438
 439         spin_lock_bh(&recent_lock);
 440         e = recent_entry_lookup(t, addr, 0);
 441         if (e == NULL) {
 442                 if (add)
 443                         recent_entry_init(t, addr, 0);
 444         } else {
 445                 if (add)
 446                         recent_entry_update(t, e);
 447                 else
 448                         recent_entry_remove(t, e);
 449         }
 450         spin_unlock_bh(&recent_lock);
 451         return size;
 452 }
 453
 454 static const struct file_operations recent_fops = {
 455         .open           = recent_seq_open,
 456         .read           = seq_read,
 457         .write          = recent_proc_write,
 458         .release        = seq_release_private,
 459         .owner          = THIS_MODULE,
 460 };
 461 #endif /* CONFIG_PROC_FS */
 462
 463 static struct xt_match recent_match __read_mostly = {
 464         .name           = "recent",
 465         .family         = AF_INET,
 466         .match          = ipt_recent_match,
 467         .matchsize      = sizeof(struct ipt_recent_info),
 468         .checkentry     = ipt_recent_checkentry,
 469         .destroy        = ipt_recent_destroy,
 470         .me             = THIS_MODULE,
 471 };
 472
 473 static int __init ipt_recent_init(void)
 474 {
 475         int err;
 476
 477         if (!ip_list_tot || !ip_pkt_list_tot || ip_pkt_list_tot > 255)
 478                 return -EINVAL;
 479         ip_list_hash_size = 1 << fls(ip_list_tot);
 480
 481         err = xt_register_match(&recent_match);
 482 #ifdef CONFIG_PROC_FS
 483         if (err)
 484                 return err;
 485         proc_dir = proc_mkdir("ipt_recent", proc_net);
 486         if (proc_dir == NULL) {
 487                 xt_unregister_match(&recent_match);
 488                 err = -ENOMEM;
 489         }
 490 #endif
 491         return err;
 492 }
 493
 494 static void __exit ipt_recent_exit(void)
 495 {
 496         BUG_ON(!list_empty(&tables));
 497         xt_unregister_match(&recent_match);
 498 #ifdef CONFIG_PROC_FS
 499         remove_proc_entry("ipt_recent", proc_net);
 500 #endif
 501 }
 502
 503 module_init(ipt_recent_init);
 504 module_exit(ipt_recent_exit);