1/* 2 * Copyright (c) 2006 Patrick McHardy <kaber@trash.net> 3 * Copyright �� CC Computer Consultants GmbH, 2007 - 2008 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License version 2 as 7 * published by the Free Software Foundation. 8 * 9 * This is a replacement of the old ipt_recent module, which carried the 10 * following copyright notice: 11 * 12 * Author: Stephen Frost <sfrost@snowman.net> 13 * Copyright 2002-2003, Stephen Frost, 2.5.x port by laforge@netfilter.org 14 */ 15#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 16#include <linux/init.h> 17#include <linux/ip.h> 18#include <linux/ipv6.h> 19#include <linux/module.h> 20#include <linux/moduleparam.h> 21#include <linux/proc_fs.h> 22#include <linux/seq_file.h> 23#include <linux/string.h> 24#include <linux/ctype.h> 25#include <linux/list.h> 26#include <linux/random.h> 27#include <linux/jhash.h> 28#include <linux/bitops.h> 29#include <linux/skbuff.h> 30#include <linux/inet.h> 31#include <linux/slab.h> 32#include <net/net_namespace.h> 33#include <net/netns/generic.h> 34 35#include <linux/netfilter/x_tables.h> 36#include <linux/netfilter/xt_recent.h> 37 38MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); 39MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>"); 40MODULE_DESCRIPTION("Xtables: \"recently-seen\" host matching"); 41MODULE_LICENSE("GPL"); 42MODULE_ALIAS("ipt_recent"); 43MODULE_ALIAS("ip6t_recent"); 44 45static unsigned int ip_list_tot = 100; 46static unsigned int ip_pkt_list_tot = 20; 47static unsigned int ip_list_hash_size = 0; 48static unsigned int ip_list_perms = 0644; 49static unsigned int ip_list_uid = 0; 50static unsigned int ip_list_gid = 0; 51module_param(ip_list_tot, uint, 0400); 52module_param(ip_pkt_list_tot, uint, 0400); 53module_param(ip_list_hash_size, uint, 0400); 54module_param(ip_list_perms, uint, 0400); 55module_param(ip_list_uid, uint, S_IRUGO | S_IWUSR); 56module_param(ip_list_gid, uint, S_IRUGO | S_IWUSR); 57MODULE_PARM_DESC(ip_list_tot, "number of IPs to remember per list"); 58MODULE_PARM_DESC(ip_pkt_list_tot, "number of packets per IP address to remember (max. 255)"); 59MODULE_PARM_DESC(ip_list_hash_size, "size of hash table used to look up IPs"); 60MODULE_PARM_DESC(ip_list_perms, "permissions on /proc/net/xt_recent/* files"); 61MODULE_PARM_DESC(ip_list_uid, "default owner of /proc/net/xt_recent/* files"); 62MODULE_PARM_DESC(ip_list_gid, "default owning group of /proc/net/xt_recent/* files"); 63 64struct recent_entry { 65 struct list_head list; 66 struct list_head lru_list; 67 union nf_inet_addr addr; 68 u_int16_t family; 69 u_int8_t ttl; 70 u_int8_t index; 71 u_int16_t nstamps; 72 unsigned long stamps[0]; 73}; 74 75struct recent_table { 76 struct list_head list; 77 char name[XT_RECENT_NAME_LEN]; 78 unsigned int refcnt; 79 unsigned int entries; 80 struct list_head lru_list; 81 struct list_head iphash[0]; 82}; 83 84struct recent_net { 85 struct list_head tables; 86#ifdef CONFIG_PROC_FS 87 struct proc_dir_entry *xt_recent; 88#endif 89}; 90 91static int recent_net_id; 92static inline struct recent_net *recent_pernet(struct net *net) 93{ 94 return net_generic(net, recent_net_id); 95} 96 97static DEFINE_SPINLOCK(recent_lock); 98static DEFINE_MUTEX(recent_mutex); 99 100#ifdef CONFIG_PROC_FS 101static const struct file_operations recent_old_fops, recent_mt_fops; 102#endif 103 104static u_int32_t hash_rnd __read_mostly; 105static bool hash_rnd_inited __read_mostly; 106 107static inline unsigned int recent_entry_hash4(const union nf_inet_addr *addr) 108{ 109 return jhash_1word((__force u32)addr->ip, hash_rnd) & 110 (ip_list_hash_size - 1); 111} 112 113static inline unsigned int recent_entry_hash6(const union nf_inet_addr *addr) 114{ 115 return jhash2((u32 *)addr->ip6, ARRAY_SIZE(addr->ip6), hash_rnd) & 116 (ip_list_hash_size - 1); 117} 118 119static struct recent_entry * 120recent_entry_lookup(const struct recent_table *table, 121 const union nf_inet_addr *addrp, u_int16_t family, 122 u_int8_t ttl) 123{ 124 struct recent_entry *e; 125 unsigned int h; 126 127 if (family == NFPROTO_IPV4) 128 h = recent_entry_hash4(addrp); 129 else 130 h = recent_entry_hash6(addrp); 131 132 list_for_each_entry(e, &table->iphash[h], list) 133 if (e->family == family && 134 memcmp(&e->addr, addrp, sizeof(e->addr)) == 0 && 135 (ttl == e->ttl || ttl == 0 || e->ttl == 0)) 136 return e; 137 return NULL; 138} 139 140static void recent_entry_remove(struct recent_table *t, struct recent_entry *e) 141{ 142 list_del(&e->list); 143 list_del(&e->lru_list); 144 kfree(e); 145 t->entries--; 146} 147 148/* 149 * Drop entries with timestamps older then 'time'. 150 */ 151static void recent_entry_reap(struct recent_table *t, unsigned long time) 152{ 153 struct recent_entry *e; 154 155 /* 156 * The head of the LRU list is always the oldest entry. 157 */ 158 e = list_entry(t->lru_list.next, struct recent_entry, lru_list); 159 160 /* 161 * The last time stamp is the most recent. 162 */ 163 if (time_after(time, e->stamps[e->index-1])) 164 recent_entry_remove(t, e); 165} 166 167static struct recent_entry * 168recent_entry_init(struct recent_table *t, const union nf_inet_addr *addr, 169 u_int16_t family, u_int8_t ttl) 170{ 171 struct recent_entry *e; 172 173 if (t->entries >= ip_list_tot) { 174 e = list_entry(t->lru_list.next, struct recent_entry, lru_list); 175 recent_entry_remove(t, e); 176 } 177 e = kmalloc(sizeof(*e) + sizeof(e->stamps[0]) * ip_pkt_list_tot, 178 GFP_ATOMIC); 179 if (e == NULL) 180 return NULL; 181 memcpy(&e->addr, addr, sizeof(e->addr)); 182 e->ttl = ttl; 183 e->stamps[0] = jiffies; 184 e->nstamps = 1; 185 e->index = 1; 186 e->family = family; 187 if (family == NFPROTO_IPV4) 188 list_add_tail(&e->list, &t->iphash[recent_entry_hash4(addr)]); 189 else 190 list_add_tail(&e->list, &t->iphash[recent_entry_hash6(addr)]); 191 list_add_tail(&e->lru_list, &t->lru_list); 192 t->entries++; 193 return e; 194} 195 196static void recent_entry_update(struct recent_table *t, struct recent_entry *e) 197{ 198 e->index %= ip_pkt_list_tot; 199 e->stamps[e->index++] = jiffies; 200 if (e->index > e->nstamps) 201 e->nstamps = e->index; 202 list_move_tail(&e->lru_list, &t->lru_list); 203} 204 205static struct recent_table *recent_table_lookup(struct recent_net *recent_net, 206 const char *name) 207{ 208 struct recent_table *t; 209 210 list_for_each_entry(t, &recent_net->tables, list) 211 if (!strcmp(t->name, name)) 212 return t; 213 return NULL; 214} 215 216static void recent_table_flush(struct recent_table *t) 217{ 218 struct recent_entry *e, *next; 219 unsigned int i; 220 221 for (i = 0; i < ip_list_hash_size; i++) 222 list_for_each_entry_safe(e, next, &t->iphash[i], list) 223 recent_entry_remove(t, e); 224} 225 226static bool 227recent_mt(const struct sk_buff *skb, struct xt_action_param *par) 228{ 229 struct net *net = dev_net(par->in ? par->in : par->out); 230 struct recent_net *recent_net = recent_pernet(net); 231 const struct xt_recent_mtinfo *info = par->matchinfo; 232 struct recent_table *t; 233 struct recent_entry *e; 234 union nf_inet_addr addr = {}; 235 u_int8_t ttl; 236 bool ret = info->invert; 237 238 if (par->family == NFPROTO_IPV4) { 239 const struct iphdr *iph = ip_hdr(skb); 240 241 if (info->side == XT_RECENT_DEST) 242 addr.ip = iph->daddr; 243 else 244 addr.ip = iph->saddr; 245 246 ttl = iph->ttl; 247 } else { 248 const struct ipv6hdr *iph = ipv6_hdr(skb); 249 250 if (info->side == XT_RECENT_DEST) 251 memcpy(&addr.in6, &iph->daddr, sizeof(addr.in6)); 252 else 253 memcpy(&addr.in6, &iph->saddr, sizeof(addr.in6)); 254 255 ttl = iph->hop_limit; 256 } 257 258 /* use TTL as seen before forwarding */ 259 if (par->out != NULL && skb->sk == NULL) 260 ttl++; 261 262 spin_lock_bh(&recent_lock); 263 t = recent_table_lookup(recent_net, info->name); 264 e = recent_entry_lookup(t, &addr, par->family, 265 (info->check_set & XT_RECENT_TTL) ? ttl : 0); 266 if (e == NULL) { 267 if (!(info->check_set & XT_RECENT_SET)) 268 goto out; 269 e = recent_entry_init(t, &addr, par->family, ttl); 270 if (e == NULL) 271 par->hotdrop = true; 272 ret = !ret; 273 goto out; 274 } 275 276 if (info->check_set & XT_RECENT_SET) 277 ret = !ret; 278 else if (info->check_set & XT_RECENT_REMOVE) { 279 recent_entry_remove(t, e); 280 ret = !ret; 281 } else if (info->check_set & (XT_RECENT_CHECK | XT_RECENT_UPDATE)) { 282 unsigned long time = jiffies - info->seconds * HZ; 283 unsigned int i, hits = 0; 284 285 for (i = 0; i < e->nstamps; i++) { 286 if (info->seconds && time_after(time, e->stamps[i])) 287 continue; 288 if (!info->hit_count || ++hits >= info->hit_count) { 289 ret = !ret; 290 break; 291 } 292 } 293 294 /* info->seconds must be non-zero */ 295 if (info->check_set & XT_RECENT_REAP) 296 recent_entry_reap(t, time); 297 } 298 299 if (info->check_set & XT_RECENT_SET || 300 (info->check_set & XT_RECENT_UPDATE && ret)) { 301 recent_entry_update(t, e); 302 e->ttl = ttl; 303 } 304out: 305 spin_unlock_bh(&recent_lock); 306 return ret; 307} 308 309static int recent_mt_check(const struct xt_mtchk_param *par) 310{ 311 struct recent_net *recent_net = recent_pernet(par->net); 312 const struct xt_recent_mtinfo *info = par->matchinfo; 313 struct recent_table *t; 314#ifdef CONFIG_PROC_FS 315 struct proc_dir_entry *pde; 316#endif 317 unsigned i; 318 int ret = -EINVAL; 319 320 if (unlikely(!hash_rnd_inited)) { 321 get_random_bytes(&hash_rnd, sizeof(hash_rnd)); 322 hash_rnd_inited = true; 323 } 324 if (info->check_set & ~XT_RECENT_VALID_FLAGS) { 325 pr_info("Unsupported user space flags (%08x)\n", 326 info->check_set); 327 return -EINVAL; 328 } 329 if (hweight8(info->check_set & 330 (XT_RECENT_SET | XT_RECENT_REMOVE | 331 XT_RECENT_CHECK | XT_RECENT_UPDATE)) != 1) 332 return -EINVAL; 333 if ((info->check_set & (XT_RECENT_SET | XT_RECENT_REMOVE)) && 334 (info->seconds || info->hit_count || 335 (info->check_set & XT_RECENT_MODIFIERS))) 336 return -EINVAL; 337 if ((info->check_set & XT_RECENT_REAP) && !info->seconds) 338 return -EINVAL; 339 if (info->hit_count > ip_pkt_list_tot) { 340 pr_info("hitcount (%u) is larger than " 341 "packets to be remembered (%u)\n", 342 info->hit_count, ip_pkt_list_tot); 343 return -EINVAL; 344 } 345 if (info->name[0] == '\0' || 346 strnlen(info->name, XT_RECENT_NAME_LEN) == XT_RECENT_NAME_LEN) 347 return -EINVAL; 348 349 mutex_lock(&recent_mutex); 350 t = recent_table_lookup(recent_net, info->name); 351 if (t != NULL) { 352 t->refcnt++; 353 ret = 0; 354 goto out; 355 } 356 357 t = kzalloc(sizeof(*t) + sizeof(t->iphash[0]) * ip_list_hash_size, 358 GFP_KERNEL); 359 if (t == NULL) { 360 ret = -ENOMEM; 361 goto out; 362 } 363 t->refcnt = 1; 364 strcpy(t->name, info->name); 365 INIT_LIST_HEAD(&t->lru_list); 366 for (i = 0; i < ip_list_hash_size; i++) 367 INIT_LIST_HEAD(&t->iphash[i]); 368#ifdef CONFIG_PROC_FS 369 pde = proc_create_data(t->name, ip_list_perms, recent_net->xt_recent, 370 &recent_mt_fops, t); 371 if (pde == NULL) { 372 kfree(t); 373 ret = -ENOMEM; 374 goto out; 375 } 376 pde->uid = ip_list_uid; 377 pde->gid = ip_list_gid; 378#endif 379 spin_lock_bh(&recent_lock); 380 list_add_tail(&t->list, &recent_net->tables); 381 spin_unlock_bh(&recent_lock); 382 ret = 0; 383out: 384 mutex_unlock(&recent_mutex); 385 return ret; 386} 387 388static void recent_mt_destroy(const struct xt_mtdtor_param *par) 389{ 390 struct recent_net *recent_net = recent_pernet(par->net); 391 const struct xt_recent_mtinfo *info = par->matchinfo; 392 struct recent_table *t; 393 394 mutex_lock(&recent_mutex); 395 t = recent_table_lookup(recent_net, info->name); 396 if (--t->refcnt == 0) { 397 spin_lock_bh(&recent_lock); 398 list_del(&t->list); 399 spin_unlock_bh(&recent_lock); 400#ifdef CONFIG_PROC_FS 401 remove_proc_entry(t->name, recent_net->xt_recent); 402#endif 403 recent_table_flush(t); 404 kfree(t); 405 } 406 mutex_unlock(&recent_mutex); 407} 408 409#ifdef CONFIG_PROC_FS 410struct recent_iter_state { 411 const struct recent_table *table; 412 unsigned int bucket; 413}; 414 415static void *recent_seq_start(struct seq_file *seq, loff_t *pos) 416 __acquires(recent_lock) 417{ 418 struct recent_iter_state *st = seq->private; 419 const struct recent_table *t = st->table; 420 struct recent_entry *e; 421 loff_t p = *pos; 422 423 spin_lock_bh(&recent_lock); 424 425 for (st->bucket = 0; st->bucket < ip_list_hash_size; st->bucket++) 426 list_for_each_entry(e, &t->iphash[st->bucket], list) 427 if (p-- == 0) 428 return e; 429 return NULL; 430} 431 432static void *recent_seq_next(struct seq_file *seq, void *v, loff_t *pos) 433{ 434 struct recent_iter_state *st = seq->private; 435 const struct recent_table *t = st->table; 436 const struct recent_entry *e = v; 437 const struct list_head *head = e->list.next; 438 439 while (head == &t->iphash[st->bucket]) { 440 if (++st->bucket >= ip_list_hash_size) 441 return NULL; 442 head = t->iphash[st->bucket].next; 443 } 444 (*pos)++; 445 return list_entry(head, struct recent_entry, list); 446} 447 448static void recent_seq_stop(struct seq_file *s, void *v) 449 __releases(recent_lock) 450{ 451 spin_unlock_bh(&recent_lock); 452} 453 454static int recent_seq_show(struct seq_file *seq, void *v) 455{ 456 const struct recent_entry *e = v; 457 unsigned int i; 458 459 i = (e->index - 1) % ip_pkt_list_tot; 460 if (e->family == NFPROTO_IPV4) 461 seq_printf(seq, "src=%pI4 ttl: %u last_seen: %lu oldest_pkt: %u", 462 &e->addr.ip, e->ttl, e->stamps[i], e->index); 463 else 464 seq_printf(seq, "src=%pI6 ttl: %u last_seen: %lu oldest_pkt: %u", 465 &e->addr.in6, e->ttl, e->stamps[i], e->index); 466 for (i = 0; i < e->nstamps; i++) 467 seq_printf(seq, "%s %lu", i ? "," : "", e->stamps[i]); 468 seq_printf(seq, "\n"); 469 return 0; 470} 471 472static const struct seq_operations recent_seq_ops = { 473 .start = recent_seq_start, 474 .next = recent_seq_next, 475 .stop = recent_seq_stop, 476 .show = recent_seq_show, 477}; 478 479static int recent_seq_open(struct inode *inode, struct file *file) 480{ 481 struct proc_dir_entry *pde = PDE(inode); 482 struct recent_iter_state *st; 483 484 st = __seq_open_private(file, &recent_seq_ops, sizeof(*st)); 485 if (st == NULL) 486 return -ENOMEM; 487 488 st->table = pde->data; 489 return 0; 490} 491 492static ssize_t 493recent_mt_proc_write(struct file *file, const char __user *input, 494 size_t size, loff_t *loff) 495{ 496 const struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); 497 struct recent_table *t = pde->data; 498 struct recent_entry *e; 499 char buf[sizeof("+b335:1d35:1e55:dead:c0de:1715:5afe:c0de")]; 500 const char *c = buf; 501 union nf_inet_addr addr = {}; 502 u_int16_t family; 503 bool add, succ; 504 505 if (size == 0) 506 return 0; 507 if (size > sizeof(buf)) 508 size = sizeof(buf); 509 if (copy_from_user(buf, input, size) != 0) 510 return -EFAULT; 511 512 /* Strict protocol! */ 513 if (*loff != 0) 514 return -ESPIPE; 515 switch (*c) { 516 case '/': /* flush table */ 517 spin_lock_bh(&recent_lock); 518 recent_table_flush(t); 519 spin_unlock_bh(&recent_lock); 520 return size; 521 case '-': /* remove address */ 522 add = false; 523 break; 524 case '+': /* add address */ 525 add = true; 526 break; 527 default: 528 pr_info("Need \"+ip\", \"-ip\" or \"/\"\n"); 529 return -EINVAL; 530 } 531 532 ++c; 533 --size; 534 if (strnchr(c, size, ':') != NULL) { 535 family = NFPROTO_IPV6; 536 succ = in6_pton(c, size, (void *)&addr, '\n', NULL); 537 } else { 538 family = NFPROTO_IPV4; 539 succ = in4_pton(c, size, (void *)&addr, '\n', NULL); 540 } 541 542 if (!succ) { 543 pr_info("illegal address written to procfs\n"); 544 return -EINVAL; 545 } 546 547 spin_lock_bh(&recent_lock); 548 e = recent_entry_lookup(t, &addr, family, 0); 549 if (e == NULL) { 550 if (add) 551 recent_entry_init(t, &addr, family, 0); 552 } else { 553 if (add) 554 recent_entry_update(t, e); 555 else 556 recent_entry_remove(t, e); 557 } 558 spin_unlock_bh(&recent_lock); 559 /* Note we removed one above */ 560 *loff += size + 1; 561 return size + 1; 562} 563 564static const struct file_operations recent_mt_fops = { 565 .open = recent_seq_open, 566 .read = seq_read, 567 .write = recent_mt_proc_write, 568 .release = seq_release_private, 569 .owner = THIS_MODULE, 570}; 571 572static int __net_init recent_proc_net_init(struct net *net) 573{ 574 struct recent_net *recent_net = recent_pernet(net); 575 576 recent_net->xt_recent = proc_mkdir("xt_recent", net->proc_net); 577 if (!recent_net->xt_recent) 578 return -ENOMEM; 579 return 0; 580} 581 582static void __net_exit recent_proc_net_exit(struct net *net) 583{ 584 proc_net_remove(net, "xt_recent"); 585} 586#else 587static inline int recent_proc_net_init(struct net *net) 588{ 589 return 0; 590} 591 592static inline void recent_proc_net_exit(struct net *net) 593{ 594} 595#endif /* CONFIG_PROC_FS */ 596 597static int __net_init recent_net_init(struct net *net) 598{ 599 struct recent_net *recent_net = recent_pernet(net); 600 601 INIT_LIST_HEAD(&recent_net->tables); 602 return recent_proc_net_init(net); 603} 604 605static void __net_exit recent_net_exit(struct net *net) 606{ 607 struct recent_net *recent_net = recent_pernet(net); 608 609 BUG_ON(!list_empty(&recent_net->tables)); 610 recent_proc_net_exit(net); 611} 612 613static struct pernet_operations recent_net_ops = { 614 .init = recent_net_init, 615 .exit = recent_net_exit, 616 .id = &recent_net_id, 617 .size = sizeof(struct recent_net), 618}; 619 620static struct xt_match recent_mt_reg[] __read_mostly = { 621 { 622 .name = "recent", 623 .revision = 0, 624 .family = NFPROTO_IPV4, 625 .match = recent_mt, 626 .matchsize = sizeof(struct xt_recent_mtinfo), 627 .checkentry = recent_mt_check, 628 .destroy = recent_mt_destroy, 629 .me = THIS_MODULE, 630 }, 631 { 632 .name = "recent", 633 .revision = 0, 634 .family = NFPROTO_IPV6, 635 .match = recent_mt, 636 .matchsize = sizeof(struct xt_recent_mtinfo), 637 .checkentry = recent_mt_check, 638 .destroy = recent_mt_destroy, 639 .me = THIS_MODULE, 640 }, 641}; 642 643static int __init recent_mt_init(void) 644{ 645 int err; 646 647 if (!ip_list_tot || !ip_pkt_list_tot || ip_pkt_list_tot > 255) 648 return -EINVAL; 649 ip_list_hash_size = 1 << fls(ip_list_tot); 650 651 err = register_pernet_subsys(&recent_net_ops); 652 if (err) 653 return err; 654 err = xt_register_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg)); 655 if (err) 656 unregister_pernet_subsys(&recent_net_ops); 657 return err; 658} 659 660static void __exit recent_mt_exit(void) 661{ 662 xt_unregister_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg)); 663 unregister_pernet_subsys(&recent_net_ops); 664} 665 666module_init(recent_mt_init); 667module_exit(recent_mt_exit); 668