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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 <linux/vmalloc.h>
33#include <net/net_namespace.h>
34#include <net/netns/generic.h>
35
36#include <linux/netfilter/x_tables.h>
37#include <linux/netfilter/xt_recent.h>
38
39MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
40MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
41MODULE_DESCRIPTION("Xtables: \"recently-seen\" host matching");
42MODULE_LICENSE("GPL");
43MODULE_ALIAS("ipt_recent");
44MODULE_ALIAS("ip6t_recent");
45
46static unsigned int ip_list_tot = 100;
47static unsigned int ip_pkt_list_tot = 20;
48static unsigned int ip_list_hash_size = 0;
49static unsigned int ip_list_perms = 0644;
50static unsigned int ip_list_uid = 0;
51static unsigned int ip_list_gid = 0;
52module_param(ip_list_tot, uint, 0400);
53module_param(ip_pkt_list_tot, uint, 0400);
54module_param(ip_list_hash_size, uint, 0400);
55module_param(ip_list_perms, uint, 0400);
56module_param(ip_list_uid, uint, S_IRUGO | S_IWUSR);
57module_param(ip_list_gid, uint, S_IRUGO | S_IWUSR);
58MODULE_PARM_DESC(ip_list_tot, "number of IPs to remember per list");
59MODULE_PARM_DESC(ip_pkt_list_tot, "number of packets per IP address to remember (max. 255)");
60MODULE_PARM_DESC(ip_list_hash_size, "size of hash table used to look up IPs");
61MODULE_PARM_DESC(ip_list_perms, "permissions on /proc/net/xt_recent/* files");
62MODULE_PARM_DESC(ip_list_uid, "default owner of /proc/net/xt_recent/* files");
63MODULE_PARM_DESC(ip_list_gid, "default owning group of /proc/net/xt_recent/* files");
64
65struct recent_entry {
66 struct list_head list;
67 struct list_head lru_list;
68 union nf_inet_addr addr;
69 u_int16_t family;
70 u_int8_t ttl;
71 u_int8_t index;
72 u_int16_t nstamps;
73 unsigned long stamps[0];
74};
75
76struct recent_table {
77 struct list_head list;
78 char name[XT_RECENT_NAME_LEN];
79 union nf_inet_addr mask;
80 unsigned int refcnt;
81 unsigned int entries;
82 struct list_head lru_list;
83 struct list_head iphash[0];
84};
85
86struct recent_net {
87 struct list_head tables;
88#ifdef CONFIG_PROC_FS
89 struct proc_dir_entry *xt_recent;
90#endif
91};
92
93static int recent_net_id;
94static inline struct recent_net *recent_pernet(struct net *net)
95{
96 return net_generic(net, recent_net_id);
97}
98
99static DEFINE_SPINLOCK(recent_lock);
100static DEFINE_MUTEX(recent_mutex);
101
102#ifdef CONFIG_PROC_FS
103static const struct file_operations recent_old_fops, recent_mt_fops;
104#endif
105
106static u_int32_t hash_rnd __read_mostly;
107static bool hash_rnd_inited __read_mostly;
108
109static inline unsigned int recent_entry_hash4(const union nf_inet_addr *addr)
110{
111 return jhash_1word((__force u32)addr->ip, hash_rnd) &
112 (ip_list_hash_size - 1);
113}
114
115static inline unsigned int recent_entry_hash6(const union nf_inet_addr *addr)
116{
117 return jhash2((u32 *)addr->ip6, ARRAY_SIZE(addr->ip6), hash_rnd) &
118 (ip_list_hash_size - 1);
119}
120
121static struct recent_entry *
122recent_entry_lookup(const struct recent_table *table,
123 const union nf_inet_addr *addrp, u_int16_t family,
124 u_int8_t ttl)
125{
126 struct recent_entry *e;
127 unsigned int h;
128
129 if (family == NFPROTO_IPV4)
130 h = recent_entry_hash4(addrp);
131 else
132 h = recent_entry_hash6(addrp);
133
134 list_for_each_entry(e, &table->iphash[h], list)
135 if (e->family == family &&
136 memcmp(&e->addr, addrp, sizeof(e->addr)) == 0 &&
137 (ttl == e->ttl || ttl == 0 || e->ttl == 0))
138 return e;
139 return NULL;
140}
141
142static void recent_entry_remove(struct recent_table *t, struct recent_entry *e)
143{
144 list_del(&e->list);
145 list_del(&e->lru_list);
146 kfree(e);
147 t->entries--;
148}
149
150
151
152
153static void recent_entry_reap(struct recent_table *t, unsigned long time)
154{
155 struct recent_entry *e;
156
157
158
159
160 e = list_entry(t->lru_list.next, struct recent_entry, lru_list);
161
162
163
164
165 if (time_after(time, e->stamps[e->index-1]))
166 recent_entry_remove(t, e);
167}
168
169static struct recent_entry *
170recent_entry_init(struct recent_table *t, const union nf_inet_addr *addr,
171 u_int16_t family, u_int8_t ttl)
172{
173 struct recent_entry *e;
174
175 if (t->entries >= ip_list_tot) {
176 e = list_entry(t->lru_list.next, struct recent_entry, lru_list);
177 recent_entry_remove(t, e);
178 }
179 e = kmalloc(sizeof(*e) + sizeof(e->stamps[0]) * ip_pkt_list_tot,
180 GFP_ATOMIC);
181 if (e == NULL)
182 return NULL;
183 memcpy(&e->addr, addr, sizeof(e->addr));
184 e->ttl = ttl;
185 e->stamps[0] = jiffies;
186 e->nstamps = 1;
187 e->index = 1;
188 e->family = family;
189 if (family == NFPROTO_IPV4)
190 list_add_tail(&e->list, &t->iphash[recent_entry_hash4(addr)]);
191 else
192 list_add_tail(&e->list, &t->iphash[recent_entry_hash6(addr)]);
193 list_add_tail(&e->lru_list, &t->lru_list);
194 t->entries++;
195 return e;
196}
197
198static void recent_entry_update(struct recent_table *t, struct recent_entry *e)
199{
200 e->index %= ip_pkt_list_tot;
201 e->stamps[e->index++] = jiffies;
202 if (e->index > e->nstamps)
203 e->nstamps = e->index;
204 list_move_tail(&e->lru_list, &t->lru_list);
205}
206
207static struct recent_table *recent_table_lookup(struct recent_net *recent_net,
208 const char *name)
209{
210 struct recent_table *t;
211
212 list_for_each_entry(t, &recent_net->tables, list)
213 if (!strcmp(t->name, name))
214 return t;
215 return NULL;
216}
217
218static void recent_table_flush(struct recent_table *t)
219{
220 struct recent_entry *e, *next;
221 unsigned int i;
222
223 for (i = 0; i < ip_list_hash_size; i++)
224 list_for_each_entry_safe(e, next, &t->iphash[i], list)
225 recent_entry_remove(t, e);
226}
227
228static bool
229recent_mt(const struct sk_buff *skb, struct xt_action_param *par)
230{
231 struct net *net = xt_net(par);
232 struct recent_net *recent_net = recent_pernet(net);
233 const struct xt_recent_mtinfo_v1 *info = par->matchinfo;
234 struct recent_table *t;
235 struct recent_entry *e;
236 union nf_inet_addr addr = {}, addr_mask;
237 u_int8_t ttl;
238 bool ret = info->invert;
239
240 if (xt_family(par) == NFPROTO_IPV4) {
241 const struct iphdr *iph = ip_hdr(skb);
242
243 if (info->side == XT_RECENT_DEST)
244 addr.ip = iph->daddr;
245 else
246 addr.ip = iph->saddr;
247
248 ttl = iph->ttl;
249 } else {
250 const struct ipv6hdr *iph = ipv6_hdr(skb);
251
252 if (info->side == XT_RECENT_DEST)
253 memcpy(&addr.in6, &iph->daddr, sizeof(addr.in6));
254 else
255 memcpy(&addr.in6, &iph->saddr, sizeof(addr.in6));
256
257 ttl = iph->hop_limit;
258 }
259
260
261 if (xt_out(par) != NULL &&
262 (!skb->sk || !net_eq(net, sock_net(skb->sk))))
263 ttl++;
264
265 spin_lock_bh(&recent_lock);
266 t = recent_table_lookup(recent_net, info->name);
267
268 nf_inet_addr_mask(&addr, &addr_mask, &t->mask);
269
270 e = recent_entry_lookup(t, &addr_mask, xt_family(par),
271 (info->check_set & XT_RECENT_TTL) ? ttl : 0);
272 if (e == NULL) {
273 if (!(info->check_set & XT_RECENT_SET))
274 goto out;
275 e = recent_entry_init(t, &addr_mask, xt_family(par), ttl);
276 if (e == NULL)
277 par->hotdrop = true;
278 ret = !ret;
279 goto out;
280 }
281
282 if (info->check_set & XT_RECENT_SET)
283 ret = !ret;
284 else if (info->check_set & XT_RECENT_REMOVE) {
285 recent_entry_remove(t, e);
286 ret = !ret;
287 } else if (info->check_set & (XT_RECENT_CHECK | XT_RECENT_UPDATE)) {
288 unsigned long time = jiffies - info->seconds * HZ;
289 unsigned int i, hits = 0;
290
291 for (i = 0; i < e->nstamps; i++) {
292 if (info->seconds && time_after(time, e->stamps[i]))
293 continue;
294 if (!info->hit_count || ++hits >= info->hit_count) {
295 ret = !ret;
296 break;
297 }
298 }
299
300
301 if (info->check_set & XT_RECENT_REAP)
302 recent_entry_reap(t, time);
303 }
304
305 if (info->check_set & XT_RECENT_SET ||
306 (info->check_set & XT_RECENT_UPDATE && ret)) {
307 recent_entry_update(t, e);
308 e->ttl = ttl;
309 }
310out:
311 spin_unlock_bh(&recent_lock);
312 return ret;
313}
314
315static void recent_table_free(void *addr)
316{
317 kvfree(addr);
318}
319
320static int recent_mt_check(const struct xt_mtchk_param *par,
321 const struct xt_recent_mtinfo_v1 *info)
322{
323 struct recent_net *recent_net = recent_pernet(par->net);
324 struct recent_table *t;
325#ifdef CONFIG_PROC_FS
326 struct proc_dir_entry *pde;
327 kuid_t uid;
328 kgid_t gid;
329#endif
330 unsigned int i;
331 int ret = -EINVAL;
332 size_t sz;
333
334 if (unlikely(!hash_rnd_inited)) {
335 get_random_bytes(&hash_rnd, sizeof(hash_rnd));
336 hash_rnd_inited = true;
337 }
338 if (info->check_set & ~XT_RECENT_VALID_FLAGS) {
339 pr_info("Unsupported user space flags (%08x)\n",
340 info->check_set);
341 return -EINVAL;
342 }
343 if (hweight8(info->check_set &
344 (XT_RECENT_SET | XT_RECENT_REMOVE |
345 XT_RECENT_CHECK | XT_RECENT_UPDATE)) != 1)
346 return -EINVAL;
347 if ((info->check_set & (XT_RECENT_SET | XT_RECENT_REMOVE)) &&
348 (info->seconds || info->hit_count ||
349 (info->check_set & XT_RECENT_MODIFIERS)))
350 return -EINVAL;
351 if ((info->check_set & XT_RECENT_REAP) && !info->seconds)
352 return -EINVAL;
353 if (info->hit_count > ip_pkt_list_tot) {
354 pr_info("hitcount (%u) is larger than "
355 "packets to be remembered (%u)\n",
356 info->hit_count, ip_pkt_list_tot);
357 return -EINVAL;
358 }
359 ret = xt_check_proc_name(info->name, sizeof(info->name));
360 if (ret)
361 return ret;
362
363 mutex_lock(&recent_mutex);
364 t = recent_table_lookup(recent_net, info->name);
365 if (t != NULL) {
366 t->refcnt++;
367 ret = 0;
368 goto out;
369 }
370
371 sz = sizeof(*t) + sizeof(t->iphash[0]) * ip_list_hash_size;
372 t = kvzalloc(sz, GFP_KERNEL);
373 if (t == NULL) {
374 ret = -ENOMEM;
375 goto out;
376 }
377 t->refcnt = 1;
378
379 memcpy(&t->mask, &info->mask, sizeof(t->mask));
380 strcpy(t->name, info->name);
381 INIT_LIST_HEAD(&t->lru_list);
382 for (i = 0; i < ip_list_hash_size; i++)
383 INIT_LIST_HEAD(&t->iphash[i]);
384#ifdef CONFIG_PROC_FS
385 uid = make_kuid(&init_user_ns, ip_list_uid);
386 gid = make_kgid(&init_user_ns, ip_list_gid);
387 if (!uid_valid(uid) || !gid_valid(gid)) {
388 recent_table_free(t);
389 ret = -EINVAL;
390 goto out;
391 }
392 pde = proc_create_data(t->name, ip_list_perms, recent_net->xt_recent,
393 &recent_mt_fops, t);
394 if (pde == NULL) {
395 recent_table_free(t);
396 ret = -ENOMEM;
397 goto out;
398 }
399 proc_set_user(pde, uid, gid);
400#endif
401 spin_lock_bh(&recent_lock);
402 list_add_tail(&t->list, &recent_net->tables);
403 spin_unlock_bh(&recent_lock);
404 ret = 0;
405out:
406 mutex_unlock(&recent_mutex);
407 return ret;
408}
409
410static int recent_mt_check_v0(const struct xt_mtchk_param *par)
411{
412 const struct xt_recent_mtinfo_v0 *info_v0 = par->matchinfo;
413 struct xt_recent_mtinfo_v1 info_v1;
414
415
416 memcpy(&info_v1, info_v0, sizeof(struct xt_recent_mtinfo));
417
418 memset(info_v1.mask.all, 0xFF, sizeof(info_v1.mask.all));
419
420 return recent_mt_check(par, &info_v1);
421}
422
423static int recent_mt_check_v1(const struct xt_mtchk_param *par)
424{
425 return recent_mt_check(par, par->matchinfo);
426}
427
428static void recent_mt_destroy(const struct xt_mtdtor_param *par)
429{
430 struct recent_net *recent_net = recent_pernet(par->net);
431 const struct xt_recent_mtinfo_v1 *info = par->matchinfo;
432 struct recent_table *t;
433
434 mutex_lock(&recent_mutex);
435 t = recent_table_lookup(recent_net, info->name);
436 if (--t->refcnt == 0) {
437 spin_lock_bh(&recent_lock);
438 list_del(&t->list);
439 spin_unlock_bh(&recent_lock);
440#ifdef CONFIG_PROC_FS
441 if (recent_net->xt_recent != NULL)
442 remove_proc_entry(t->name, recent_net->xt_recent);
443#endif
444 recent_table_flush(t);
445 recent_table_free(t);
446 }
447 mutex_unlock(&recent_mutex);
448}
449
450#ifdef CONFIG_PROC_FS
451struct recent_iter_state {
452 const struct recent_table *table;
453 unsigned int bucket;
454};
455
456static void *recent_seq_start(struct seq_file *seq, loff_t *pos)
457 __acquires(recent_lock)
458{
459 struct recent_iter_state *st = seq->private;
460 const struct recent_table *t = st->table;
461 struct recent_entry *e;
462 loff_t p = *pos;
463
464 spin_lock_bh(&recent_lock);
465
466 for (st->bucket = 0; st->bucket < ip_list_hash_size; st->bucket++)
467 list_for_each_entry(e, &t->iphash[st->bucket], list)
468 if (p-- == 0)
469 return e;
470 return NULL;
471}
472
473static void *recent_seq_next(struct seq_file *seq, void *v, loff_t *pos)
474{
475 struct recent_iter_state *st = seq->private;
476 const struct recent_table *t = st->table;
477 const struct recent_entry *e = v;
478 const struct list_head *head = e->list.next;
479
480 while (head == &t->iphash[st->bucket]) {
481 if (++st->bucket >= ip_list_hash_size)
482 return NULL;
483 head = t->iphash[st->bucket].next;
484 }
485 (*pos)++;
486 return list_entry(head, struct recent_entry, list);
487}
488
489static void recent_seq_stop(struct seq_file *s, void *v)
490 __releases(recent_lock)
491{
492 spin_unlock_bh(&recent_lock);
493}
494
495static int recent_seq_show(struct seq_file *seq, void *v)
496{
497 const struct recent_entry *e = v;
498 unsigned int i;
499
500 i = (e->index - 1) % ip_pkt_list_tot;
501 if (e->family == NFPROTO_IPV4)
502 seq_printf(seq, "src=%pI4 ttl: %u last_seen: %lu oldest_pkt: %u",
503 &e->addr.ip, e->ttl, e->stamps[i], e->index);
504 else
505 seq_printf(seq, "src=%pI6 ttl: %u last_seen: %lu oldest_pkt: %u",
506 &e->addr.in6, e->ttl, e->stamps[i], e->index);
507 for (i = 0; i < e->nstamps; i++)
508 seq_printf(seq, "%s %lu", i ? "," : "", e->stamps[i]);
509 seq_printf(seq, "\n");
510 return 0;
511}
512
513static const struct seq_operations recent_seq_ops = {
514 .start = recent_seq_start,
515 .next = recent_seq_next,
516 .stop = recent_seq_stop,
517 .show = recent_seq_show,
518};
519
520static int recent_seq_open(struct inode *inode, struct file *file)
521{
522 struct recent_iter_state *st;
523
524 st = __seq_open_private(file, &recent_seq_ops, sizeof(*st));
525 if (st == NULL)
526 return -ENOMEM;
527
528 st->table = PDE_DATA(inode);
529 return 0;
530}
531
532static ssize_t
533recent_mt_proc_write(struct file *file, const char __user *input,
534 size_t size, loff_t *loff)
535{
536 struct recent_table *t = PDE_DATA(file_inode(file));
537 struct recent_entry *e;
538 char buf[sizeof("+b335:1d35:1e55:dead:c0de:1715:5afe:c0de")];
539 const char *c = buf;
540 union nf_inet_addr addr = {};
541 u_int16_t family;
542 bool add, succ;
543
544 if (size == 0)
545 return 0;
546 if (size > sizeof(buf))
547 size = sizeof(buf);
548 if (copy_from_user(buf, input, size) != 0)
549 return -EFAULT;
550
551
552 if (*loff != 0)
553 return -ESPIPE;
554 switch (*c) {
555 case '/':
556 spin_lock_bh(&recent_lock);
557 recent_table_flush(t);
558 spin_unlock_bh(&recent_lock);
559 return size;
560 case '-':
561 add = false;
562 break;
563 case '+':
564 add = true;
565 break;
566 default:
567 pr_info("Need \"+ip\", \"-ip\" or \"/\"\n");
568 return -EINVAL;
569 }
570
571 ++c;
572 --size;
573 if (strnchr(c, size, ':') != NULL) {
574 family = NFPROTO_IPV6;
575 succ = in6_pton(c, size, (void *)&addr, '\n', NULL);
576 } else {
577 family = NFPROTO_IPV4;
578 succ = in4_pton(c, size, (void *)&addr, '\n', NULL);
579 }
580
581 if (!succ) {
582 pr_info("illegal address written to procfs\n");
583 return -EINVAL;
584 }
585
586 spin_lock_bh(&recent_lock);
587 e = recent_entry_lookup(t, &addr, family, 0);
588 if (e == NULL) {
589 if (add)
590 recent_entry_init(t, &addr, family, 0);
591 } else {
592 if (add)
593 recent_entry_update(t, e);
594 else
595 recent_entry_remove(t, e);
596 }
597 spin_unlock_bh(&recent_lock);
598
599 *loff += size + 1;
600 return size + 1;
601}
602
603static const struct file_operations recent_mt_fops = {
604 .open = recent_seq_open,
605 .read = seq_read,
606 .write = recent_mt_proc_write,
607 .release = seq_release_private,
608 .owner = THIS_MODULE,
609 .llseek = seq_lseek,
610};
611
612static int __net_init recent_proc_net_init(struct net *net)
613{
614 struct recent_net *recent_net = recent_pernet(net);
615
616 recent_net->xt_recent = proc_mkdir("xt_recent", net->proc_net);
617 if (!recent_net->xt_recent)
618 return -ENOMEM;
619 return 0;
620}
621
622static void __net_exit recent_proc_net_exit(struct net *net)
623{
624 struct recent_net *recent_net = recent_pernet(net);
625 struct recent_table *t;
626
627
628
629
630
631 spin_lock_bh(&recent_lock);
632 list_for_each_entry(t, &recent_net->tables, list)
633 remove_proc_entry(t->name, recent_net->xt_recent);
634
635 recent_net->xt_recent = NULL;
636 spin_unlock_bh(&recent_lock);
637
638 remove_proc_entry("xt_recent", net->proc_net);
639}
640#else
641static inline int recent_proc_net_init(struct net *net)
642{
643 return 0;
644}
645
646static inline void recent_proc_net_exit(struct net *net)
647{
648}
649#endif
650
651static int __net_init recent_net_init(struct net *net)
652{
653 struct recent_net *recent_net = recent_pernet(net);
654
655 INIT_LIST_HEAD(&recent_net->tables);
656 return recent_proc_net_init(net);
657}
658
659static void __net_exit recent_net_exit(struct net *net)
660{
661 recent_proc_net_exit(net);
662}
663
664static struct pernet_operations recent_net_ops = {
665 .init = recent_net_init,
666 .exit = recent_net_exit,
667 .id = &recent_net_id,
668 .size = sizeof(struct recent_net),
669};
670
671static struct xt_match recent_mt_reg[] __read_mostly = {
672 {
673 .name = "recent",
674 .revision = 0,
675 .family = NFPROTO_IPV4,
676 .match = recent_mt,
677 .matchsize = sizeof(struct xt_recent_mtinfo),
678 .checkentry = recent_mt_check_v0,
679 .destroy = recent_mt_destroy,
680 .me = THIS_MODULE,
681 },
682 {
683 .name = "recent",
684 .revision = 0,
685 .family = NFPROTO_IPV6,
686 .match = recent_mt,
687 .matchsize = sizeof(struct xt_recent_mtinfo),
688 .checkentry = recent_mt_check_v0,
689 .destroy = recent_mt_destroy,
690 .me = THIS_MODULE,
691 },
692 {
693 .name = "recent",
694 .revision = 1,
695 .family = NFPROTO_IPV4,
696 .match = recent_mt,
697 .matchsize = sizeof(struct xt_recent_mtinfo_v1),
698 .checkentry = recent_mt_check_v1,
699 .destroy = recent_mt_destroy,
700 .me = THIS_MODULE,
701 },
702 {
703 .name = "recent",
704 .revision = 1,
705 .family = NFPROTO_IPV6,
706 .match = recent_mt,
707 .matchsize = sizeof(struct xt_recent_mtinfo_v1),
708 .checkentry = recent_mt_check_v1,
709 .destroy = recent_mt_destroy,
710 .me = THIS_MODULE,
711 }
712};
713
714static int __init recent_mt_init(void)
715{
716 int err;
717
718 if (!ip_list_tot || !ip_pkt_list_tot || ip_pkt_list_tot > 255)
719 return -EINVAL;
720 ip_list_hash_size = 1 << fls(ip_list_tot);
721
722 err = register_pernet_subsys(&recent_net_ops);
723 if (err)
724 return err;
725 err = xt_register_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
726 if (err)
727 unregister_pernet_subsys(&recent_net_ops);
728 return err;
729}
730
731static void __exit recent_mt_exit(void)
732{
733 xt_unregister_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
734 unregister_pernet_subsys(&recent_net_ops);
735}
736
737module_init(recent_mt_init);
738module_exit(recent_mt_exit);
739
