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 static unsigned int ip_list_uid = 0;
  39 static unsigned int ip_list_gid = 0;
  40 module_param(ip_list_tot, uint, 0400);
  41 module_param(ip_pkt_list_tot, uint, 0400);
  42 module_param(ip_list_hash_size, uint, 0400);
  43 module_param(ip_list_perms, uint, 0400);
  44 module_param(ip_list_uid, uint, 0400);
  45 module_param(ip_list_gid, uint, 0400);
  46 MODULE_PARM_DESC(ip_list_tot, "number of IPs to remember per list");
  47 MODULE_PARM_DESC(ip_pkt_list_tot, "number of packets per IP to remember (max. 255)");
  48 MODULE_PARM_DESC(ip_list_hash_size, "size of hash table used to look up IPs");
  49 MODULE_PARM_DESC(ip_list_perms, "permissions on /proc/net/ipt_recent/* files");
  50 MODULE_PARM_DESC(ip_list_uid,"owner of /proc/net/ipt_recent/* files");
  51 MODULE_PARM_DESC(ip_list_gid,"owning group of /proc/net/ipt_recent/* files");
  52
  53 struct recent_entry {
  54         struct list_head        list;
  55         struct list_head        lru_list;
  56         __be32                  addr;
  57         u_int8_t                ttl;
  58         u_int8_t                index;
  59         u_int16_t               nstamps;
  60         unsigned long           stamps[0];
  61 };
  62
  63 struct recent_table {
  64         struct list_head        list;
  65         char                    name[IPT_RECENT_NAME_LEN];
  66 #ifdef CONFIG_PROC_FS
  67         struct proc_dir_entry   *proc;
  68 #endif
  69         unsigned int            refcnt;
  70         unsigned int            entries;
  71         struct list_head        lru_list;
  72         struct list_head        iphash[0];
  73 };
  74
  75 static LIST_HEAD(tables);
  76 static DEFINE_SPINLOCK(recent_lock);
  77 static DEFINE_MUTEX(recent_mutex);
  78
  79 #ifdef CONFIG_PROC_FS
  80 static struct proc_dir_entry    *proc_dir;
  81 static struct file_operations   recent_fops;
  82 #endif
  83
  84 static u_int32_t hash_rnd;
  85 static int hash_rnd_initted;
  86
  87 static unsigned int recent_entry_hash(__be32 addr)
  88 {
  89         if (!hash_rnd_initted) {
  90                 get_random_bytes(&hash_rnd, 4);
  91                 hash_rnd_initted = 1;
  92         }
  93         return jhash_1word((__force u32)addr, hash_rnd) & (ip_list_hash_size - 1);
  94 }
  95
  96 static struct recent_entry *
  97 recent_entry_lookup(const struct recent_table *table, __be32 addr, u_int8_t ttl)
  98 {
  99         struct recent_entry *e;
 100         unsigned int h;
 101
 102         h = recent_entry_hash(addr);
 103         list_for_each_entry(e, &table->iphash[h], list)
 104                 if (e->addr == addr && (ttl == e->ttl || !ttl || !e->ttl))
 105                         return e;
 106         return NULL;
 107 }
 108
 109 static void recent_entry_remove(struct recent_table *t, struct recent_entry *e)
 110 {
 111         list_del(&e->list);
 112         list_del(&e->lru_list);
 113         kfree(e);
 114         t->entries--;
 115 }
 116
 117 static struct recent_entry *
 118 recent_entry_init(struct recent_table *t, __be32 addr, u_int8_t ttl)
 119 {
 120         struct recent_entry *e;
 121
 122         if (t->entries >= ip_list_tot) {
 123                 e = list_entry(t->lru_list.next, struct recent_entry, lru_list);
 124                 recent_entry_remove(t, e);
 125         }
 126         e = kmalloc(sizeof(*e) + sizeof(e->stamps[0]) * ip_pkt_list_tot,
 127                     GFP_ATOMIC);
 128         if (e == NULL)
 129                 return NULL;
 130         e->addr      = addr;
 131         e->ttl       = ttl;
 132         e->stamps[0] = jiffies;
 133         e->nstamps   = 1;
 134         e->index     = 1;
 135         list_add_tail(&e->list, &t->iphash[recent_entry_hash(addr)]);
 136         list_add_tail(&e->lru_list, &t->lru_list);
 137         t->entries++;
 138         return e;
 139 }
 140
 141 static void recent_entry_update(struct recent_table *t, struct recent_entry *e)
 142 {
 143         e->stamps[e->index++] = jiffies;
 144         if (e->index > e->nstamps)
 145                 e->nstamps = e->index;
 146         e->index %= ip_pkt_list_tot;
 147         list_move_tail(&e->lru_list, &t->lru_list);
 148 }
 149
 150 static struct recent_table *recent_table_lookup(const char *name)
 151 {
 152         struct recent_table *t;
 153
 154         list_for_each_entry(t, &tables, list)
 155                 if (!strcmp(t->name, name))
 156                         return t;
 157         return NULL;
 158 }
 159
 160 static void recent_table_flush(struct recent_table *t)
 161 {
 162         struct recent_entry *e, *next;
 163         unsigned int i;
 164
 165         for (i = 0; i < ip_list_hash_size; i++) {
 166                 list_for_each_entry_safe(e, next, &t->iphash[i], list)
 167                         recent_entry_remove(t, e);
 168         }
 169 }
 170
 171 static int
 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, int *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         int ret = info->invert;
 183
 184         if (info->side == IPT_RECENT_DEST)
 185                 addr = skb->nh.iph->daddr;
 186         else
 187                 addr = skb->nh.iph->saddr;
 188
 189         ttl = skb->nh.iph->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 = 1;
 204                 ret ^= 1;
 205                 goto out;
 206         }
 207
 208         if (info->check_set & IPT_RECENT_SET)
 209                 ret ^= 1;
 210         else if (info->check_set & IPT_RECENT_REMOVE) {
 211                 recent_entry_remove(t, e);
 212                 ret ^= 1;
 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 ^= 1;
 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 int
 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         int ret = 0;
 246
 247         if (hweight8(info->check_set &
 248                      (IPT_RECENT_SET | IPT_RECENT_REMOVE |
 249                       IPT_RECENT_CHECK | IPT_RECENT_UPDATE)) != 1)
 250                 return 0;
 251         if ((info->check_set & (IPT_RECENT_SET | IPT_RECENT_REMOVE)) &&
 252             (info->seconds || info->hit_count))
 253                 return 0;
 254         if (info->name[0] == '\0' ||
 255             strnlen(info->name, IPT_RECENT_NAME_LEN) == IPT_RECENT_NAME_LEN)
 256                 return 0;
 257
 258         mutex_lock(&recent_mutex);
 259         t = recent_table_lookup(info->name);
 260         if (t != NULL) {
 261                 t->refcnt++;
 262                 ret = 1;
 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 = 1;
 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         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                 }
 336         }
 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 {
 358         spin_unlock_bh(&recent_lock);
 359 }
 360
 361 static int recent_seq_show(struct seq_file *seq, void *v)
 362 {
 363         struct recent_entry *e = v;
 364         unsigned int i;
 365
 366         i = (e->index - 1) % ip_pkt_list_tot;
 367         seq_printf(seq, "src=%u.%u.%u.%u ttl: %u last_seen: %lu oldest_pkt: %u",
 368                    NIPQUAD(e->addr), e->ttl, e->stamps[i], e->index);
 369         for (i = 0; i < e->nstamps; i++)
 370                 seq_printf(seq, "%s %lu", i ? "," : "", e->stamps[i]);
 371         seq_printf(seq, "\n");
 372         return 0;
 373 }
 374
 375 static struct seq_operations recent_seq_ops = {
 376         .start          = recent_seq_start,
 377         .next           = recent_seq_next,
 378         .stop           = recent_seq_stop,
 379         .show           = recent_seq_show,
 380 };
 381
 382 static int recent_seq_open(struct inode *inode, struct file *file)
 383 {
 384         struct proc_dir_entry *pde = PDE(inode);
 385         struct seq_file *seq;
 386         struct recent_iter_state *st;
 387         int ret;
 388
 389         st = kzalloc(sizeof(*st), GFP_KERNEL);
 390         if (st == NULL)
 391                 return -ENOMEM;
 392         ret = seq_open(file, &recent_seq_ops);
 393         if (ret)
 394                 kfree(st);
 395         st->table    = pde->data;
 396         seq          = file->private_data;
 397         seq->private = st;
 398         return ret;
 399 }
 400
 401 static ssize_t recent_proc_write(struct file *file, const char __user *input,
 402                                  size_t size, loff_t *loff)
 403 {
 404         struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
 405         struct recent_table *t = pde->data;
 406         struct recent_entry *e;
 407         char buf[sizeof("+255.255.255.255")], *c = buf;
 408         __be32 addr;
 409         int add;
 410
 411         if (size > sizeof(buf))
 412                 size = sizeof(buf);
 413         if (copy_from_user(buf, input, size))
 414                 return -EFAULT;
 415         while (isspace(*c))
 416                 c++;
 417
 418         if (size - (c - buf) < 5)
 419                 return c - buf;
 420         if (!strncmp(c, "clear", 5)) {
 421                 c += 5;
 422                 spin_lock_bh(&recent_lock);
 423                 recent_table_flush(t);
 424                 spin_unlock_bh(&recent_lock);
 425                 return c - buf;
 426         }
 427
 428         switch (*c) {
 429         case '-':
 430                 add = 0;
 431                 c++;
 432                 break;
 433         case '+':
 434                 c++;
 435         default:
 436                 add = 1;
 437                 break;
 438         }
 439         addr = in_aton(c);
 440
 441         spin_lock_bh(&recent_lock);
 442         e = recent_entry_lookup(t, addr, 0);
 443         if (e == NULL) {
 444                 if (add)
 445                         recent_entry_init(t, addr, 0);
 446         } else {
 447                 if (add)
 448                         recent_entry_update(t, e);
 449                 else
 450                         recent_entry_remove(t, e);
 451         }
 452         spin_unlock_bh(&recent_lock);
 453         return size;
 454 }
 455
 456 static struct file_operations recent_fops = {
 457         .open           = recent_seq_open,
 458         .read           = seq_read,
 459         .write          = recent_proc_write,
 460         .release        = seq_release_private,
 461         .owner          = THIS_MODULE,
 462 };
 463 #endif /* CONFIG_PROC_FS */
 464
 465 static struct ipt_match recent_match = {
 466         .name           = "recent",
 467         .match          = ipt_recent_match,
 468         .matchsize      = sizeof(struct ipt_recent_info),
 469         .checkentry     = ipt_recent_checkentry,
 470         .destroy        = ipt_recent_destroy,
 471         .me             = THIS_MODULE,
 472 };
 473
 474 static int __init ipt_recent_init(void)
 475 {
 476         int err;
 477
 478         if (!ip_list_tot || !ip_pkt_list_tot || ip_pkt_list_tot > 255)
 479                 return -EINVAL;
 480         ip_list_hash_size = 1 << fls(ip_list_tot);
 481
 482         err = ipt_register_match(&recent_match);
 483 #ifdef CONFIG_PROC_FS
 484         if (err)
 485                 return err;
 486         proc_dir = proc_mkdir("ipt_recent", proc_net);
 487         if (proc_dir == NULL) {
 488                 ipt_unregister_match(&recent_match);
 489                 err = -ENOMEM;
 490         }
 491 #endif
 492         return err;
 493 }
 494
 495 static void __exit ipt_recent_exit(void)
 496 {
 497         BUG_ON(!list_empty(&tables));
 498         ipt_unregister_match(&recent_match);
 499 #ifdef CONFIG_PROC_FS
 500         remove_proc_entry("ipt_recent", proc_net);
 501 #endif
 502 }
 503
 504 module_init(ipt_recent_init);
 505 module_exit(ipt_recent_exit);