1
2
3
4
5
6
7
8
9
10
11
12
13
14
15#include <linux/init.h>
16#include <linux/ip.h>
17#include <linux/ipv6.h>
18#include <linux/module.h>
19#include <linux/moduleparam.h>
20#include <linux/proc_fs.h>
21#include <linux/seq_file.h>
22#include <linux/string.h>
23#include <linux/ctype.h>
24#include <linux/list.h>
25#include <linux/random.h>
26#include <linux/jhash.h>
27#include <linux/bitops.h>
28#include <linux/skbuff.h>
29#include <linux/inet.h>
30#include <net/net_namespace.h>
31
32#include <linux/netfilter/x_tables.h>
33#include <linux/netfilter/xt_recent.h>
34
35MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
36MODULE_AUTHOR("Jan Engelhardt <jengelh@computergmbh.de>");
37MODULE_DESCRIPTION("Xtables: \"recently-seen\" host matching for IPv4");
38MODULE_LICENSE("GPL");
39MODULE_ALIAS("ipt_recent");
40MODULE_ALIAS("ip6t_recent");
41
42static unsigned int ip_list_tot = 100;
43static unsigned int ip_pkt_list_tot = 20;
44static unsigned int ip_list_hash_size = 0;
45static unsigned int ip_list_perms = 0644;
46static unsigned int ip_list_uid = 0;
47static unsigned int ip_list_gid = 0;
48module_param(ip_list_tot, uint, 0400);
49module_param(ip_pkt_list_tot, uint, 0400);
50module_param(ip_list_hash_size, uint, 0400);
51module_param(ip_list_perms, uint, 0400);
52module_param(ip_list_uid, uint, 0400);
53module_param(ip_list_gid, uint, 0400);
54MODULE_PARM_DESC(ip_list_tot, "number of IPs to remember per list");
55MODULE_PARM_DESC(ip_pkt_list_tot, "number of packets per IP to remember (max. 255)");
56MODULE_PARM_DESC(ip_list_hash_size, "size of hash table used to look up IPs");
57MODULE_PARM_DESC(ip_list_perms, "permissions on /proc/net/xt_recent/* files");
58MODULE_PARM_DESC(ip_list_uid,"owner of /proc/net/xt_recent/* files");
59MODULE_PARM_DESC(ip_list_gid,"owning group of /proc/net/xt_recent/* files");
60
61struct recent_entry {
62 struct list_head list;
63 struct list_head lru_list;
64 union nf_inet_addr addr;
65 u_int16_t family;
66 u_int8_t ttl;
67 u_int8_t index;
68 u_int16_t nstamps;
69 unsigned long stamps[0];
70};
71
72struct recent_table {
73 struct list_head list;
74 char name[XT_RECENT_NAME_LEN];
75 unsigned int refcnt;
76 unsigned int entries;
77 struct list_head lru_list;
78 struct list_head iphash[0];
79};
80
81static LIST_HEAD(tables);
82static DEFINE_SPINLOCK(recent_lock);
83static DEFINE_MUTEX(recent_mutex);
84
85#ifdef CONFIG_PROC_FS
86#ifdef CONFIG_NETFILTER_XT_MATCH_RECENT_PROC_COMPAT
87static struct proc_dir_entry *proc_old_dir;
88#endif
89static struct proc_dir_entry *recent_proc_dir;
90static const struct file_operations recent_old_fops, recent_mt_fops;
91#endif
92
93static u_int32_t hash_rnd;
94static bool hash_rnd_initted;
95
96static unsigned int recent_entry_hash4(const union nf_inet_addr *addr)
97{
98 if (!hash_rnd_initted) {
99 get_random_bytes(&hash_rnd, sizeof(hash_rnd));
100 hash_rnd_initted = true;
101 }
102 return jhash_1word((__force u32)addr->ip, hash_rnd) &
103 (ip_list_hash_size - 1);
104}
105
106static unsigned int recent_entry_hash6(const union nf_inet_addr *addr)
107{
108 if (!hash_rnd_initted) {
109 get_random_bytes(&hash_rnd, sizeof(hash_rnd));
110 hash_rnd_initted = true;
111 }
112 return jhash2((u32 *)addr->ip6, ARRAY_SIZE(addr->ip6), hash_rnd) &
113 (ip_list_hash_size - 1);
114}
115
116static struct recent_entry *
117recent_entry_lookup(const struct recent_table *table,
118 const union nf_inet_addr *addrp, u_int16_t family,
119 u_int8_t ttl)
120{
121 struct recent_entry *e;
122 unsigned int h;
123
124 if (family == NFPROTO_IPV4)
125 h = recent_entry_hash4(addrp);
126 else
127 h = recent_entry_hash6(addrp);
128
129 list_for_each_entry(e, &table->iphash[h], list)
130 if (e->family == family &&
131 memcmp(&e->addr, addrp, sizeof(e->addr)) == 0 &&
132 (ttl == e->ttl || ttl == 0 || e->ttl == 0))
133 return e;
134 return NULL;
135}
136
137static void recent_entry_remove(struct recent_table *t, struct recent_entry *e)
138{
139 list_del(&e->list);
140 list_del(&e->lru_list);
141 kfree(e);
142 t->entries--;
143}
144
145static struct recent_entry *
146recent_entry_init(struct recent_table *t, const union nf_inet_addr *addr,
147 u_int16_t family, u_int8_t ttl)
148{
149 struct recent_entry *e;
150
151 if (t->entries >= ip_list_tot) {
152 e = list_entry(t->lru_list.next, struct recent_entry, lru_list);
153 recent_entry_remove(t, e);
154 }
155 e = kmalloc(sizeof(*e) + sizeof(e->stamps[0]) * ip_pkt_list_tot,
156 GFP_ATOMIC);
157 if (e == NULL)
158 return NULL;
159 memcpy(&e->addr, addr, sizeof(e->addr));
160 e->ttl = ttl;
161 e->stamps[0] = jiffies;
162 e->nstamps = 1;
163 e->index = 1;
164 e->family = family;
165 if (family == NFPROTO_IPV4)
166 list_add_tail(&e->list, &t->iphash[recent_entry_hash4(addr)]);
167 else
168 list_add_tail(&e->list, &t->iphash[recent_entry_hash6(addr)]);
169 list_add_tail(&e->lru_list, &t->lru_list);
170 t->entries++;
171 return e;
172}
173
174static void recent_entry_update(struct recent_table *t, struct recent_entry *e)
175{
176 e->stamps[e->index++] = jiffies;
177 if (e->index > e->nstamps)
178 e->nstamps = e->index;
179 e->index %= ip_pkt_list_tot;
180 list_move_tail(&e->lru_list, &t->lru_list);
181}
182
183static struct recent_table *recent_table_lookup(const char *name)
184{
185 struct recent_table *t;
186
187 list_for_each_entry(t, &tables, list)
188 if (!strcmp(t->name, name))
189 return t;
190 return NULL;
191}
192
193static void recent_table_flush(struct recent_table *t)
194{
195 struct recent_entry *e, *next;
196 unsigned int i;
197
198 for (i = 0; i < ip_list_hash_size; i++)
199 list_for_each_entry_safe(e, next, &t->iphash[i], list)
200 recent_entry_remove(t, e);
201}
202
203static bool
204recent_mt(const struct sk_buff *skb, const struct xt_match_param *par)
205{
206 const struct xt_recent_mtinfo *info = par->matchinfo;
207 struct recent_table *t;
208 struct recent_entry *e;
209 union nf_inet_addr addr = {};
210 u_int8_t ttl;
211 bool ret = info->invert;
212
213 if (par->match->family == NFPROTO_IPV4) {
214 const struct iphdr *iph = ip_hdr(skb);
215
216 if (info->side == XT_RECENT_DEST)
217 addr.ip = iph->daddr;
218 else
219 addr.ip = iph->saddr;
220
221 ttl = iph->ttl;
222 } else {
223 const struct ipv6hdr *iph = ipv6_hdr(skb);
224
225 if (info->side == XT_RECENT_DEST)
226 memcpy(&addr.in6, &iph->daddr, sizeof(addr.in6));
227 else
228 memcpy(&addr.in6, &iph->saddr, sizeof(addr.in6));
229
230 ttl = iph->hop_limit;
231 }
232
233
234 if (par->out != NULL && skb->sk == NULL)
235 ttl++;
236
237 spin_lock_bh(&recent_lock);
238 t = recent_table_lookup(info->name);
239 e = recent_entry_lookup(t, &addr, par->match->family,
240 (info->check_set & XT_RECENT_TTL) ? ttl : 0);
241 if (e == NULL) {
242 if (!(info->check_set & XT_RECENT_SET))
243 goto out;
244 e = recent_entry_init(t, &addr, par->match->family, ttl);
245 if (e == NULL)
246 *par->hotdrop = true;
247 ret = !ret;
248 goto out;
249 }
250
251 if (info->check_set & XT_RECENT_SET)
252 ret = !ret;
253 else if (info->check_set & XT_RECENT_REMOVE) {
254 recent_entry_remove(t, e);
255 ret = !ret;
256 } else if (info->check_set & (XT_RECENT_CHECK | XT_RECENT_UPDATE)) {
257 unsigned long time = jiffies - info->seconds * HZ;
258 unsigned int i, hits = 0;
259
260 for (i = 0; i < e->nstamps; i++) {
261 if (info->seconds && time_after(time, e->stamps[i]))
262 continue;
263 if (++hits >= info->hit_count) {
264 ret = !ret;
265 break;
266 }
267 }
268 }
269
270 if (info->check_set & XT_RECENT_SET ||
271 (info->check_set & XT_RECENT_UPDATE && ret)) {
272 recent_entry_update(t, e);
273 e->ttl = ttl;
274 }
275out:
276 spin_unlock_bh(&recent_lock);
277 return ret;
278}
279
280static bool recent_mt_check(const struct xt_mtchk_param *par)
281{
282 const struct xt_recent_mtinfo *info = par->matchinfo;
283 struct recent_table *t;
284#ifdef CONFIG_PROC_FS
285 struct proc_dir_entry *pde;
286#endif
287 unsigned i;
288 bool ret = false;
289
290 if (hweight8(info->check_set &
291 (XT_RECENT_SET | XT_RECENT_REMOVE |
292 XT_RECENT_CHECK | XT_RECENT_UPDATE)) != 1)
293 return false;
294 if ((info->check_set & (XT_RECENT_SET | XT_RECENT_REMOVE)) &&
295 (info->seconds || info->hit_count))
296 return false;
297 if (info->hit_count > ip_pkt_list_tot)
298 return false;
299 if (info->name[0] == '\0' ||
300 strnlen(info->name, XT_RECENT_NAME_LEN) == XT_RECENT_NAME_LEN)
301 return false;
302
303 mutex_lock(&recent_mutex);
304 t = recent_table_lookup(info->name);
305 if (t != NULL) {
306 t->refcnt++;
307 ret = true;
308 goto out;
309 }
310
311 t = kzalloc(sizeof(*t) + sizeof(t->iphash[0]) * ip_list_hash_size,
312 GFP_KERNEL);
313 if (t == NULL)
314 goto out;
315 t->refcnt = 1;
316 strcpy(t->name, info->name);
317 INIT_LIST_HEAD(&t->lru_list);
318 for (i = 0; i < ip_list_hash_size; i++)
319 INIT_LIST_HEAD(&t->iphash[i]);
320#ifdef CONFIG_PROC_FS
321 pde = proc_create_data(t->name, ip_list_perms, recent_proc_dir,
322 &recent_mt_fops, t);
323 if (pde == NULL) {
324 kfree(t);
325 goto out;
326 }
327 pde->uid = ip_list_uid;
328 pde->gid = ip_list_gid;
329#ifdef CONFIG_NETFILTER_XT_MATCH_RECENT_PROC_COMPAT
330 pde = proc_create_data(t->name, ip_list_perms, proc_old_dir,
331 &recent_old_fops, t);
332 if (pde == NULL) {
333 remove_proc_entry(t->name, proc_old_dir);
334 kfree(t);
335 goto out;
336 }
337 pde->uid = ip_list_uid;
338 pde->gid = ip_list_gid;
339#endif
340#endif
341 spin_lock_bh(&recent_lock);
342 list_add_tail(&t->list, &tables);
343 spin_unlock_bh(&recent_lock);
344 ret = true;
345out:
346 mutex_unlock(&recent_mutex);
347 return ret;
348}
349
350static void recent_mt_destroy(const struct xt_mtdtor_param *par)
351{
352 const struct xt_recent_mtinfo *info = par->matchinfo;
353 struct recent_table *t;
354
355 mutex_lock(&recent_mutex);
356 t = recent_table_lookup(info->name);
357 if (--t->refcnt == 0) {
358 spin_lock_bh(&recent_lock);
359 list_del(&t->list);
360 spin_unlock_bh(&recent_lock);
361#ifdef CONFIG_PROC_FS
362#ifdef CONFIG_NETFILTER_XT_MATCH_RECENT_PROC_COMPAT
363 remove_proc_entry(t->name, proc_old_dir);
364#endif
365 remove_proc_entry(t->name, recent_proc_dir);
366#endif
367 recent_table_flush(t);
368 kfree(t);
369 }
370 mutex_unlock(&recent_mutex);
371}
372
373#ifdef CONFIG_PROC_FS
374struct recent_iter_state {
375 const struct recent_table *table;
376 unsigned int bucket;
377};
378
379static void *recent_seq_start(struct seq_file *seq, loff_t *pos)
380 __acquires(recent_lock)
381{
382 struct recent_iter_state *st = seq->private;
383 const struct recent_table *t = st->table;
384 struct recent_entry *e;
385 loff_t p = *pos;
386
387 spin_lock_bh(&recent_lock);
388
389 for (st->bucket = 0; st->bucket < ip_list_hash_size; st->bucket++)
390 list_for_each_entry(e, &t->iphash[st->bucket], list)
391 if (p-- == 0)
392 return e;
393 return NULL;
394}
395
396static void *recent_seq_next(struct seq_file *seq, void *v, loff_t *pos)
397{
398 struct recent_iter_state *st = seq->private;
399 const struct recent_table *t = st->table;
400 const struct recent_entry *e = v;
401 const struct list_head *head = e->list.next;
402
403 while (head == &t->iphash[st->bucket]) {
404 if (++st->bucket >= ip_list_hash_size)
405 return NULL;
406 head = t->iphash[st->bucket].next;
407 }
408 (*pos)++;
409 return list_entry(head, struct recent_entry, list);
410}
411
412static void recent_seq_stop(struct seq_file *s, void *v)
413 __releases(recent_lock)
414{
415 spin_unlock_bh(&recent_lock);
416}
417
418static int recent_seq_show(struct seq_file *seq, void *v)
419{
420 const struct recent_entry *e = v;
421 unsigned int i;
422
423 i = (e->index - 1) % ip_pkt_list_tot;
424 if (e->family == NFPROTO_IPV4)
425 seq_printf(seq, "src=%pI4 ttl: %u last_seen: %lu oldest_pkt: %u",
426 &e->addr.ip, e->ttl, e->stamps[i], e->index);
427 else
428 seq_printf(seq, "src=%pI6 ttl: %u last_seen: %lu oldest_pkt: %u",
429 &e->addr.in6, e->ttl, e->stamps[i], e->index);
430 for (i = 0; i < e->nstamps; i++)
431 seq_printf(seq, "%s %lu", i ? "," : "", e->stamps[i]);
432 seq_printf(seq, "\n");
433 return 0;
434}
435
436static const struct seq_operations recent_seq_ops = {
437 .start = recent_seq_start,
438 .next = recent_seq_next,
439 .stop = recent_seq_stop,
440 .show = recent_seq_show,
441};
442
443static int recent_seq_open(struct inode *inode, struct file *file)
444{
445 struct proc_dir_entry *pde = PDE(inode);
446 struct recent_iter_state *st;
447
448 st = __seq_open_private(file, &recent_seq_ops, sizeof(*st));
449 if (st == NULL)
450 return -ENOMEM;
451
452 st->table = pde->data;
453 return 0;
454}
455
456#ifdef CONFIG_NETFILTER_XT_MATCH_RECENT_PROC_COMPAT
457static int recent_old_seq_open(struct inode *inode, struct file *filp)
458{
459 static bool warned_of_old;
460
461 if (unlikely(!warned_of_old)) {
462 printk(KERN_INFO KBUILD_MODNAME ": Use of /proc/net/ipt_recent"
463 " is deprecated; use /proc/net/xt_recent.\n");
464 warned_of_old = true;
465 }
466 return recent_seq_open(inode, filp);
467}
468
469static ssize_t recent_old_proc_write(struct file *file,
470 const char __user *input,
471 size_t size, loff_t *loff)
472{
473 const struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
474 struct recent_table *t = pde->data;
475 struct recent_entry *e;
476 char buf[sizeof("+255.255.255.255")], *c = buf;
477 union nf_inet_addr addr = {};
478 int add;
479
480 if (size > sizeof(buf))
481 size = sizeof(buf);
482 if (copy_from_user(buf, input, size))
483 return -EFAULT;
484
485 while (isspace(*c))
486 c++;
487
488 if (size - (c - buf) < 5)
489 return c - buf;
490 if (!strncmp(c, "clear", 5)) {
491 c += 5;
492 spin_lock_bh(&recent_lock);
493 recent_table_flush(t);
494 spin_unlock_bh(&recent_lock);
495 return c - buf;
496 }
497
498 switch (*c) {
499 case '-':
500 add = 0;
501 c++;
502 break;
503 case '+':
504 c++;
505 default:
506 add = 1;
507 break;
508 }
509 addr.ip = in_aton(c);
510
511 spin_lock_bh(&recent_lock);
512 e = recent_entry_lookup(t, &addr, NFPROTO_IPV4, 0);
513 if (e == NULL) {
514 if (add)
515 recent_entry_init(t, &addr, NFPROTO_IPV4, 0);
516 } else {
517 if (add)
518 recent_entry_update(t, e);
519 else
520 recent_entry_remove(t, e);
521 }
522 spin_unlock_bh(&recent_lock);
523 return size;
524}
525
526static const struct file_operations recent_old_fops = {
527 .open = recent_old_seq_open,
528 .read = seq_read,
529 .write = recent_old_proc_write,
530 .release = seq_release_private,
531 .owner = THIS_MODULE,
532};
533#endif
534
535static ssize_t
536recent_mt_proc_write(struct file *file, const char __user *input,
537 size_t size, loff_t *loff)
538{
539 const struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
540 struct recent_table *t = pde->data;
541 struct recent_entry *e;
542 char buf[sizeof("+b335:1d35:1e55:dead:c0de:1715:5afe:c0de")];
543 const char *c = buf;
544 union nf_inet_addr addr = {};
545 u_int16_t family;
546 bool add, succ;
547
548 if (size == 0)
549 return 0;
550 if (size > sizeof(buf))
551 size = sizeof(buf);
552 if (copy_from_user(buf, input, size) != 0)
553 return -EFAULT;
554
555
556 if (*loff != 0)
557 return -ESPIPE;
558 switch (*c) {
559 case '/':
560 spin_lock_bh(&recent_lock);
561 recent_table_flush(t);
562 spin_unlock_bh(&recent_lock);
563 return size;
564 case '-':
565 add = false;
566 break;
567 case '+':
568 add = true;
569 break;
570 default:
571 printk(KERN_INFO KBUILD_MODNAME ": Need +ip, -ip or /\n");
572 return -EINVAL;
573 }
574
575 ++c;
576 --size;
577 if (strnchr(c, size, ':') != NULL) {
578 family = NFPROTO_IPV6;
579 succ = in6_pton(c, size, (void *)&addr, '\n', NULL);
580 } else {
581 family = NFPROTO_IPV4;
582 succ = in4_pton(c, size, (void *)&addr, '\n', NULL);
583 }
584
585 if (!succ) {
586 printk(KERN_INFO KBUILD_MODNAME ": illegal address written "
587 "to procfs\n");
588 return -EINVAL;
589 }
590
591 spin_lock_bh(&recent_lock);
592 e = recent_entry_lookup(t, &addr, family, 0);
593 if (e == NULL) {
594 if (add)
595 recent_entry_init(t, &addr, family, 0);
596 } else {
597 if (add)
598 recent_entry_update(t, e);
599 else
600 recent_entry_remove(t, e);
601 }
602 spin_unlock_bh(&recent_lock);
603
604 *loff += size + 1;
605 return size + 1;
606}
607
608static const struct file_operations recent_mt_fops = {
609 .open = recent_seq_open,
610 .read = seq_read,
611 .write = recent_mt_proc_write,
612 .release = seq_release_private,
613 .owner = THIS_MODULE,
614};
615#endif
616
617static struct xt_match recent_mt_reg[] __read_mostly = {
618 {
619 .name = "recent",
620 .revision = 0,
621 .family = NFPROTO_IPV4,
622 .match = recent_mt,
623 .matchsize = sizeof(struct xt_recent_mtinfo),
624 .checkentry = recent_mt_check,
625 .destroy = recent_mt_destroy,
626 .me = THIS_MODULE,
627 },
628 {
629 .name = "recent",
630 .revision = 0,
631 .family = NFPROTO_IPV6,
632 .match = recent_mt,
633 .matchsize = sizeof(struct xt_recent_mtinfo),
634 .checkentry = recent_mt_check,
635 .destroy = recent_mt_destroy,
636 .me = THIS_MODULE,
637 },
638};
639
640static int __init recent_mt_init(void)
641{
642 int err;
643
644 if (!ip_list_tot || !ip_pkt_list_tot || ip_pkt_list_tot > 255)
645 return -EINVAL;
646 ip_list_hash_size = 1 << fls(ip_list_tot);
647
648 err = xt_register_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
649#ifdef CONFIG_PROC_FS
650 if (err)
651 return err;
652 recent_proc_dir = proc_mkdir("xt_recent", init_net.proc_net);
653 if (recent_proc_dir == NULL) {
654 xt_unregister_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
655 err = -ENOMEM;
656 }
657#ifdef CONFIG_NETFILTER_XT_MATCH_RECENT_PROC_COMPAT
658 if (err < 0)
659 return err;
660 proc_old_dir = proc_mkdir("ipt_recent", init_net.proc_net);
661 if (proc_old_dir == NULL) {
662 remove_proc_entry("xt_recent", init_net.proc_net);
663 xt_unregister_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
664 err = -ENOMEM;
665 }
666#endif
667#endif
668 return err;
669}
670
671static void __exit recent_mt_exit(void)
672{
673 BUG_ON(!list_empty(&tables));
674 xt_unregister_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
675#ifdef CONFIG_PROC_FS
676#ifdef CONFIG_NETFILTER_XT_MATCH_RECENT_PROC_COMPAT
677 remove_proc_entry("ipt_recent", init_net.proc_net);
678#endif
679 remove_proc_entry("xt_recent", init_net.proc_net);
680#endif
681}
682
683module_init(recent_mt_init);
684module_exit(recent_mt_exit);
685
