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 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 = !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->name[0] == '\0' ||
 256             strnlen(info->name, IPT_RECENT_NAME_LEN) == IPT_RECENT_NAME_LEN)
 257                 return false;
 258
 259         mutex_lock(&recent_mutex);
 260         t = recent_table_lookup(info->name);
 261         if (t != NULL) {
 262                 t->refcnt++;
 263                 ret = true;
 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 = true;
 291 out:
 292         mutex_unlock(&recent_mutex);
 293         return ret;
 294 }
 295
 296 static void recent_mt_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 recent_iter_state *st;
 384
 385         st = __seq_open_private(file, &recent_seq_ops, sizeof(*st));
 386         if (st == NULL)
 387                 return -ENOMEM;
 388
 389         st->table    = pde->data;
 390         return 0;
 391 }
 392
 393 static ssize_t recent_proc_write(struct file *file, const char __user *input,
 394                                  size_t size, loff_t *loff)
 395 {
 396         struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
 397         struct recent_table *t = pde->data;
 398         struct recent_entry *e;
 399         char buf[sizeof("+255.255.255.255")], *c = buf;
 400         __be32 addr;
 401         int add;
 402
 403         if (size > sizeof(buf))
 404                 size = sizeof(buf);
 405         if (copy_from_user(buf, input, size))
 406                 return -EFAULT;
 407         while (isspace(*c))
 408                 c++;
 409
 410         if (size - (c - buf) < 5)
 411                 return c - buf;
 412         if (!strncmp(c, "clear", 5)) {
 413                 c += 5;
 414                 spin_lock_bh(&recent_lock);
 415                 recent_table_flush(t);
 416                 spin_unlock_bh(&recent_lock);
 417                 return c - buf;
 418         }
 419
 420         switch (*c) {
 421         case '-':
 422                 add = 0;
 423                 c++;
 424                 break;
 425         case '+':
 426                 c++;
 427         default:
 428                 add = 1;
 429                 break;
 430         }
 431         addr = in_aton(c);
 432
 433         spin_lock_bh(&recent_lock);
 434         e = recent_entry_lookup(t, addr, 0);
 435         if (e == NULL) {
 436                 if (add)
 437                         recent_entry_init(t, addr, 0);
 438         } else {
 439                 if (add)
 440                         recent_entry_update(t, e);
 441                 else
 442                         recent_entry_remove(t, e);
 443         }
 444         spin_unlock_bh(&recent_lock);
 445         return size;
 446 }
 447
 448 static const struct file_operations recent_fops = {
 449         .open           = recent_seq_open,
 450         .read           = seq_read,
 451         .write          = recent_proc_write,
 452         .release        = seq_release_private,
 453         .owner          = THIS_MODULE,
 454 };
 455 #endif /* CONFIG_PROC_FS */
 456
 457 static struct xt_match recent_mt_reg __read_mostly = {
 458         .name           = "recent",
 459         .family         = AF_INET,
 460         .match          = recent_mt,
 461         .matchsize      = sizeof(struct ipt_recent_info),
 462         .checkentry     = recent_mt_check,
 463         .destroy        = recent_mt_destroy,
 464         .me             = THIS_MODULE,
 465 };
 466
 467 static int __init recent_mt_init(void)
 468 {
 469         int err;
 470
 471         if (!ip_list_tot || !ip_pkt_list_tot || ip_pkt_list_tot > 255)
 472                 return -EINVAL;
 473         ip_list_hash_size = 1 << fls(ip_list_tot);
 474
 475         err = xt_register_match(&recent_mt_reg);
 476 #ifdef CONFIG_PROC_FS
 477         if (err)
 478                 return err;
 479         proc_dir = proc_mkdir("ipt_recent", init_net.proc_net);
 480         if (proc_dir == NULL) {
 481                 xt_unregister_match(&recent_mt_reg);
 482                 err = -ENOMEM;
 483         }
 484 #endif
 485         return err;
 486 }
 487
 488 static void __exit recent_mt_exit(void)
 489 {
 490         BUG_ON(!list_empty(&tables));
 491         xt_unregister_match(&recent_mt_reg);
 492 #ifdef CONFIG_PROC_FS
 493         remove_proc_entry("ipt_recent", init_net.proc_net);
 494 #endif
 495 }
 496
 497 module_init(recent_mt_init);
 498 module_exit(recent_mt_exit);