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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 = dev_net(par->in ? par->in : par->out);
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 (par->family == 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 (par->out != NULL && skb->sk == NULL)
262 ttl++;
263
264 spin_lock_bh(&recent_lock);
265 t = recent_table_lookup(recent_net, info->name);
266
267 nf_inet_addr_mask(&addr, &addr_mask, &t->mask);
268
269 e = recent_entry_lookup(t, &addr_mask, par->family,
270 (info->check_set & XT_RECENT_TTL) ? ttl : 0);
271 if (e == NULL) {
272 if (!(info->check_set & XT_RECENT_SET))
273 goto out;
274 e = recent_entry_init(t, &addr_mask, par->family, ttl);
275 if (e == NULL)
276 par->hotdrop = true;
277 ret = !ret;
278 goto out;
279 }
280
281 if (info->check_set & XT_RECENT_SET)
282 ret = !ret;
283 else if (info->check_set & XT_RECENT_REMOVE) {
284 recent_entry_remove(t, e);
285 ret = !ret;
286 } else if (info->check_set & (XT_RECENT_CHECK | XT_RECENT_UPDATE)) {
287 unsigned long time = jiffies - info->seconds * HZ;
288 unsigned int i, hits = 0;
289
290 for (i = 0; i < e->nstamps; i++) {
291 if (info->seconds && time_after(time, e->stamps[i]))
292 continue;
293 if (!info->hit_count || ++hits >= info->hit_count) {
294 ret = !ret;
295 break;
296 }
297 }
298
299
300 if (info->check_set & XT_RECENT_REAP)
301 recent_entry_reap(t, time);
302 }
303
304 if (info->check_set & XT_RECENT_SET ||
305 (info->check_set & XT_RECENT_UPDATE && ret)) {
306 recent_entry_update(t, e);
307 e->ttl = ttl;
308 }
309out:
310 spin_unlock_bh(&recent_lock);
311 return ret;
312}
313
314static void recent_table_free(void *addr)
315{
316 if (is_vmalloc_addr(addr))
317 vfree(addr);
318 else
319 kfree(addr);
320}
321
322static int recent_mt_check(const struct xt_mtchk_param *par,
323 const struct xt_recent_mtinfo_v1 *info)
324{
325 struct recent_net *recent_net = recent_pernet(par->net);
326 struct recent_table *t;
327#ifdef CONFIG_PROC_FS
328 struct proc_dir_entry *pde;
329 kuid_t uid;
330 kgid_t gid;
331#endif
332 unsigned int i;
333 int ret = -EINVAL;
334 size_t sz;
335
336 if (unlikely(!hash_rnd_inited)) {
337 get_random_bytes(&hash_rnd, sizeof(hash_rnd));
338 hash_rnd_inited = true;
339 }
340 if (info->check_set & ~XT_RECENT_VALID_FLAGS) {
341 pr_info("Unsupported user space flags (%08x)\n",
342 info->check_set);
343 return -EINVAL;
344 }
345 if (hweight8(info->check_set &
346 (XT_RECENT_SET | XT_RECENT_REMOVE |
347 XT_RECENT_CHECK | XT_RECENT_UPDATE)) != 1)
348 return -EINVAL;
349 if ((info->check_set & (XT_RECENT_SET | XT_RECENT_REMOVE)) &&
350 (info->seconds || info->hit_count ||
351 (info->check_set & XT_RECENT_MODIFIERS)))
352 return -EINVAL;
353 if ((info->check_set & XT_RECENT_REAP) && !info->seconds)
354 return -EINVAL;
355 if (info->hit_count > ip_pkt_list_tot) {
356 pr_info("hitcount (%u) is larger than "
357 "packets to be remembered (%u)\n",
358 info->hit_count, ip_pkt_list_tot);
359 return -EINVAL;
360 }
361 if (info->name[0] == '\0' ||
362 strnlen(info->name, XT_RECENT_NAME_LEN) == XT_RECENT_NAME_LEN)
363 return -EINVAL;
364
365 mutex_lock(&recent_mutex);
366 t = recent_table_lookup(recent_net, info->name);
367 if (t != NULL) {
368 t->refcnt++;
369 ret = 0;
370 goto out;
371 }
372
373 sz = sizeof(*t) + sizeof(t->iphash[0]) * ip_list_hash_size;
374 if (sz <= PAGE_SIZE)
375 t = kzalloc(sz, GFP_KERNEL);
376 else
377 t = vzalloc(sz);
378 if (t == NULL) {
379 ret = -ENOMEM;
380 goto out;
381 }
382 t->refcnt = 1;
383
384 memcpy(&t->mask, &info->mask, sizeof(t->mask));
385 strcpy(t->name, info->name);
386 INIT_LIST_HEAD(&t->lru_list);
387 for (i = 0; i < ip_list_hash_size; i++)
388 INIT_LIST_HEAD(&t->iphash[i]);
389#ifdef CONFIG_PROC_FS
390 uid = make_kuid(&init_user_ns, ip_list_uid);
391 gid = make_kgid(&init_user_ns, ip_list_gid);
392 if (!uid_valid(uid) || !gid_valid(gid)) {
393 recent_table_free(t);
394 ret = -EINVAL;
395 goto out;
396 }
397 pde = proc_create_data(t->name, ip_list_perms, recent_net->xt_recent,
398 &recent_mt_fops, t);
399 if (pde == NULL) {
400 recent_table_free(t);
401 ret = -ENOMEM;
402 goto out;
403 }
404 proc_set_user(pde, uid, gid);
405#endif
406 spin_lock_bh(&recent_lock);
407 list_add_tail(&t->list, &recent_net->tables);
408 spin_unlock_bh(&recent_lock);
409 ret = 0;
410out:
411 mutex_unlock(&recent_mutex);
412 return ret;
413}
414
415static int recent_mt_check_v0(const struct xt_mtchk_param *par)
416{
417 const struct xt_recent_mtinfo_v0 *info_v0 = par->matchinfo;
418 struct xt_recent_mtinfo_v1 info_v1;
419
420
421 memcpy(&info_v1, info_v0, sizeof(struct xt_recent_mtinfo));
422
423 memset(info_v1.mask.all, 0xFF, sizeof(info_v1.mask.all));
424
425 return recent_mt_check(par, &info_v1);
426}
427
428static int recent_mt_check_v1(const struct xt_mtchk_param *par)
429{
430 return recent_mt_check(par, par->matchinfo);
431}
432
433static void recent_mt_destroy(const struct xt_mtdtor_param *par)
434{
435 struct recent_net *recent_net = recent_pernet(par->net);
436 const struct xt_recent_mtinfo_v1 *info = par->matchinfo;
437 struct recent_table *t;
438
439 mutex_lock(&recent_mutex);
440 t = recent_table_lookup(recent_net, info->name);
441 if (--t->refcnt == 0) {
442 spin_lock_bh(&recent_lock);
443 list_del(&t->list);
444 spin_unlock_bh(&recent_lock);
445#ifdef CONFIG_PROC_FS
446 if (recent_net->xt_recent != NULL)
447 remove_proc_entry(t->name, recent_net->xt_recent);
448#endif
449 recent_table_flush(t);
450 recent_table_free(t);
451 }
452 mutex_unlock(&recent_mutex);
453}
454
455#ifdef CONFIG_PROC_FS
456struct recent_iter_state {
457 const struct recent_table *table;
458 unsigned int bucket;
459};
460
461static void *recent_seq_start(struct seq_file *seq, loff_t *pos)
462 __acquires(recent_lock)
463{
464 struct recent_iter_state *st = seq->private;
465 const struct recent_table *t = st->table;
466 struct recent_entry *e;
467 loff_t p = *pos;
468
469 spin_lock_bh(&recent_lock);
470
471 for (st->bucket = 0; st->bucket < ip_list_hash_size; st->bucket++)
472 list_for_each_entry(e, &t->iphash[st->bucket], list)
473 if (p-- == 0)
474 return e;
475 return NULL;
476}
477
478static void *recent_seq_next(struct seq_file *seq, void *v, loff_t *pos)
479{
480 struct recent_iter_state *st = seq->private;
481 const struct recent_table *t = st->table;
482 const struct recent_entry *e = v;
483 const struct list_head *head = e->list.next;
484
485 while (head == &t->iphash[st->bucket]) {
486 if (++st->bucket >= ip_list_hash_size)
487 return NULL;
488 head = t->iphash[st->bucket].next;
489 }
490 (*pos)++;
491 return list_entry(head, struct recent_entry, list);
492}
493
494static void recent_seq_stop(struct seq_file *s, void *v)
495 __releases(recent_lock)
496{
497 spin_unlock_bh(&recent_lock);
498}
499
500static int recent_seq_show(struct seq_file *seq, void *v)
501{
502 const struct recent_entry *e = v;
503 unsigned int i;
504
505 i = (e->index - 1) % ip_pkt_list_tot;
506 if (e->family == NFPROTO_IPV4)
507 seq_printf(seq, "src=%pI4 ttl: %u last_seen: %lu oldest_pkt: %u",
508 &e->addr.ip, e->ttl, e->stamps[i], e->index);
509 else
510 seq_printf(seq, "src=%pI6 ttl: %u last_seen: %lu oldest_pkt: %u",
511 &e->addr.in6, e->ttl, e->stamps[i], e->index);
512 for (i = 0; i < e->nstamps; i++)
513 seq_printf(seq, "%s %lu", i ? "," : "", e->stamps[i]);
514 seq_printf(seq, "\n");
515 return 0;
516}
517
518static const struct seq_operations recent_seq_ops = {
519 .start = recent_seq_start,
520 .next = recent_seq_next,
521 .stop = recent_seq_stop,
522 .show = recent_seq_show,
523};
524
525static int recent_seq_open(struct inode *inode, struct file *file)
526{
527 struct recent_iter_state *st;
528
529 st = __seq_open_private(file, &recent_seq_ops, sizeof(*st));
530 if (st == NULL)
531 return -ENOMEM;
532
533 st->table = PDE_DATA(inode);
534 return 0;
535}
536
537static ssize_t
538recent_mt_proc_write(struct file *file, const char __user *input,
539 size_t size, loff_t *loff)
540{
541 struct recent_table *t = PDE_DATA(file_inode(file));
542 struct recent_entry *e;
543 char buf[sizeof("+b335:1d35:1e55:dead:c0de:1715:5afe:c0de")];
544 const char *c = buf;
545 union nf_inet_addr addr = {};
546 u_int16_t family;
547 bool add, succ;
548
549 if (size == 0)
550 return 0;
551 if (size > sizeof(buf))
552 size = sizeof(buf);
553 if (copy_from_user(buf, input, size) != 0)
554 return -EFAULT;
555
556
557 if (*loff != 0)
558 return -ESPIPE;
559 switch (*c) {
560 case '/':
561 spin_lock_bh(&recent_lock);
562 recent_table_flush(t);
563 spin_unlock_bh(&recent_lock);
564 return size;
565 case '-':
566 add = false;
567 break;
568 case '+':
569 add = true;
570 break;
571 default:
572 pr_info("Need \"+ip\", \"-ip\" or \"/\"\n");
573 return -EINVAL;
574 }
575
576 ++c;
577 --size;
578 if (strnchr(c, size, ':') != NULL) {
579 family = NFPROTO_IPV6;
580 succ = in6_pton(c, size, (void *)&addr, '\n', NULL);
581 } else {
582 family = NFPROTO_IPV4;
583 succ = in4_pton(c, size, (void *)&addr, '\n', NULL);
584 }
585
586 if (!succ) {
587 pr_info("illegal address written 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 .llseek = seq_lseek,
615};
616
617static int __net_init recent_proc_net_init(struct net *net)
618{
619 struct recent_net *recent_net = recent_pernet(net);
620
621 recent_net->xt_recent = proc_mkdir("xt_recent", net->proc_net);
622 if (!recent_net->xt_recent)
623 return -ENOMEM;
624 return 0;
625}
626
627static void __net_exit recent_proc_net_exit(struct net *net)
628{
629 struct recent_net *recent_net = recent_pernet(net);
630 struct recent_table *t;
631
632
633
634
635
636 spin_lock_bh(&recent_lock);
637 list_for_each_entry(t, &recent_net->tables, list)
638 remove_proc_entry(t->name, recent_net->xt_recent);
639
640 recent_net->xt_recent = NULL;
641 spin_unlock_bh(&recent_lock);
642
643 remove_proc_entry("xt_recent", net->proc_net);
644}
645#else
646static inline int recent_proc_net_init(struct net *net)
647{
648 return 0;
649}
650
651static inline void recent_proc_net_exit(struct net *net)
652{
653}
654#endif
655
656static int __net_init recent_net_init(struct net *net)
657{
658 struct recent_net *recent_net = recent_pernet(net);
659
660 INIT_LIST_HEAD(&recent_net->tables);
661 return recent_proc_net_init(net);
662}
663
664static void __net_exit recent_net_exit(struct net *net)
665{
666 recent_proc_net_exit(net);
667}
668
669static struct pernet_operations recent_net_ops = {
670 .init = recent_net_init,
671 .exit = recent_net_exit,
672 .id = &recent_net_id,
673 .size = sizeof(struct recent_net),
674};
675
676static struct xt_match recent_mt_reg[] __read_mostly = {
677 {
678 .name = "recent",
679 .revision = 0,
680 .family = NFPROTO_IPV4,
681 .match = recent_mt,
682 .matchsize = sizeof(struct xt_recent_mtinfo),
683 .checkentry = recent_mt_check_v0,
684 .destroy = recent_mt_destroy,
685 .me = THIS_MODULE,
686 },
687 {
688 .name = "recent",
689 .revision = 0,
690 .family = NFPROTO_IPV6,
691 .match = recent_mt,
692 .matchsize = sizeof(struct xt_recent_mtinfo),
693 .checkentry = recent_mt_check_v0,
694 .destroy = recent_mt_destroy,
695 .me = THIS_MODULE,
696 },
697 {
698 .name = "recent",
699 .revision = 1,
700 .family = NFPROTO_IPV4,
701 .match = recent_mt,
702 .matchsize = sizeof(struct xt_recent_mtinfo_v1),
703 .checkentry = recent_mt_check_v1,
704 .destroy = recent_mt_destroy,
705 .me = THIS_MODULE,
706 },
707 {
708 .name = "recent",
709 .revision = 1,
710 .family = NFPROTO_IPV6,
711 .match = recent_mt,
712 .matchsize = sizeof(struct xt_recent_mtinfo_v1),
713 .checkentry = recent_mt_check_v1,
714 .destroy = recent_mt_destroy,
715 .me = THIS_MODULE,
716 }
717};
718
719static int __init recent_mt_init(void)
720{
721 int err;
722
723 if (!ip_list_tot || !ip_pkt_list_tot || ip_pkt_list_tot > 255)
724 return -EINVAL;
725 ip_list_hash_size = 1 << fls(ip_list_tot);
726
727 err = register_pernet_subsys(&recent_net_ops);
728 if (err)
729 return err;
730 err = xt_register_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
731 if (err)
732 unregister_pernet_subsys(&recent_net_ops);
733 return err;
734}
735
736static void __exit recent_mt_exit(void)
737{
738 xt_unregister_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
739 unregister_pernet_subsys(&recent_net_ops);
740}
741
742module_init(recent_mt_init);
743module_exit(recent_mt_exit);
744
