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 31MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); 32MODULE_DESCRIPTION("IP tables recently seen matching module"); 33MODULE_LICENSE("GPL"); 34 35static unsigned int ip_list_tot = 100; 36static unsigned int ip_pkt_list_tot = 20; 37static unsigned int ip_list_hash_size = 0; 38static unsigned int ip_list_perms = 0644; 39static unsigned int ip_list_uid = 0; 40static unsigned int ip_list_gid = 0; 41module_param(ip_list_tot, uint, 0400); 42module_param(ip_pkt_list_tot, uint, 0400); 43module_param(ip_list_hash_size, uint, 0400); 44module_param(ip_list_perms, uint, 0400); 45module_param(ip_list_uid, uint, 0400); 46module_param(ip_list_gid, uint, 0400); 47MODULE_PARM_DESC(ip_list_tot, "number of IPs to remember per list"); 48MODULE_PARM_DESC(ip_pkt_list_tot, "number of packets per IP to remember (max. 255)"); 49MODULE_PARM_DESC(ip_list_hash_size, "size of hash table used to look up IPs"); 50MODULE_PARM_DESC(ip_list_perms, "permissions on /proc/net/ipt_recent/* files"); 51MODULE_PARM_DESC(ip_list_uid,"owner of /proc/net/ipt_recent/* files"); 52MODULE_PARM_DESC(ip_list_gid,"owning group of /proc/net/ipt_recent/* files"); 53 54struct 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 64struct 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 76static LIST_HEAD(tables); 77static DEFINE_SPINLOCK(recent_lock); 78static DEFINE_MUTEX(recent_mutex); 79 80#ifdef CONFIG_PROC_FS 81static struct proc_dir_entry *proc_dir; 82static const struct file_operations recent_fops; 83#endif 84 85static u_int32_t hash_rnd; 86static int hash_rnd_initted; 87 88static 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 97static struct recent_entry * 98recent_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 110static 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 118static struct recent_entry * 119recent_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 142static 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 151static 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 161static 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 172static int 173ipt_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 } 233out: 234 spin_unlock_bh(&recent_lock); 235 return ret; 236} 237 238static int 239ipt_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; 291out: 292 mutex_unlock(&recent_mutex); 293 return ret; 294} 295 296static void 297ipt_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 318struct recent_iter_state { 319 struct recent_table *table; 320 unsigned int bucket; 321}; 322 323static 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 341static 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 357static void recent_seq_stop(struct seq_file *s, void *v) 358{ 359 spin_unlock_bh(&recent_lock); 360} 361 362static 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 376static 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 383static 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 402static 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 457static 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 466static 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 476static 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 497static 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 506module_init(ipt_recent_init); 507module_exit(ipt_recent_exit); 508