1 /* iptables match extension to limit the number of packets per second
2 * seperately for each hashbucket (sourceip/sourceport/dstip/dstport)
4 * (C) 2003-2004 by Harald Welte <laforge@netfilter.org>
6 * $Id: ipt_hashlimit.c 3244 2004-10-20 16:24:29Z laforge@netfilter.org $
8 * Development of this code was funded by Astaro AG, http://www.astaro.com/
10 * based on ipt_limit.c by:
11 * Jérôme de Vivie <devivie@info.enserb.u-bordeaux.fr>
12 * Hervé Eychenne <eychenne@info.enserb.u-bordeaux.fr>
13 * Rusty Russell <rusty@rustcorp.com.au>
15 * The general idea is to create a hash table for every dstip and have a
16 * seperate limit counter per tuple. This way you can do something like 'limit
17 * the number of syn packets for each of my internal addresses.
19 * Ideally this would just be implemented as a general 'hash' match, which would
20 * allow us to attach any iptables target to it's hash buckets. But this is
21 * not possible in the current iptables architecture. As always, pkttables for
24 #include <linux/module.h>
25 #include <linux/skbuff.h>
26 #include <linux/spinlock.h>
27 #include <linux/random.h>
28 #include <linux/jhash.h>
29 #include <linux/slab.h>
30 #include <linux/vmalloc.h>
31 #include <linux/tcp.h>
32 #include <linux/udp.h>
33 #include <linux/sctp.h>
34 #include <linux/proc_fs.h>
35 #include <linux/seq_file.h>
36 #include <linux/list.h>
38 #include <linux/netfilter_ipv4/ip_tables.h>
39 #include <linux/netfilter_ipv4/ipt_hashlimit.h>
41 /* FIXME: this is just for IP_NF_ASSERRT */
42 #include <linux/netfilter_ipv4/ip_conntrack.h>
44 MODULE_LICENSE("GPL");
45 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
46 MODULE_DESCRIPTION("iptables match for limiting per hash-bucket");
48 /* need to declare this at the top */
49 static struct proc_dir_entry *hashlimit_procdir;
50 static struct file_operations dl_file_ops;
57 /* ports have to be consecutive !!! */
63 /* static / read-only parts in the beginning */
64 struct hlist_node node;
65 struct dsthash_dst dst;
67 /* modified structure members in the end */
68 unsigned long expires; /* precalculated expiry time */
70 unsigned long prev; /* last modification */
72 u_int32_t credit_cap, cost;
76 struct ipt_hashlimit_htable {
77 struct hlist_node node; /* global list of all htables */
80 struct hashlimit_cfg cfg; /* config */
83 spinlock_t lock; /* lock for list_head */
84 u_int32_t rnd; /* random seed for hash */
85 struct timer_list timer; /* timer for gc */
86 atomic_t count; /* number entries in table */
89 struct proc_dir_entry *pde;
91 struct hlist_head hash[0]; /* hashtable itself */
94 static DEFINE_SPINLOCK(hashlimit_lock); /* protects htables list */
95 static DECLARE_MUTEX(hlimit_mutex); /* additional checkentry protection */
96 static HLIST_HEAD(hashlimit_htables);
97 static kmem_cache_t *hashlimit_cachep __read_mostly;
99 static inline int dst_cmp(const struct dsthash_ent *ent, struct dsthash_dst *b)
101 return (ent->dst.dst_ip == b->dst_ip
102 && ent->dst.dst_port == b->dst_port
103 && ent->dst.src_port == b->src_port
104 && ent->dst.src_ip == b->src_ip);
107 static inline u_int32_t
108 hash_dst(const struct ipt_hashlimit_htable *ht, const struct dsthash_dst *dst)
110 return (jhash_3words(dst->dst_ip, (dst->dst_port<<16 | dst->src_port),
111 dst->src_ip, ht->rnd) % ht->cfg.size);
114 static inline struct dsthash_ent *
115 __dsthash_find(const struct ipt_hashlimit_htable *ht, struct dsthash_dst *dst)
117 struct dsthash_ent *ent;
118 struct hlist_node *pos;
119 u_int32_t hash = hash_dst(ht, dst);
121 if (!hlist_empty(&ht->hash[hash]))
122 hlist_for_each_entry(ent, pos, &ht->hash[hash], node) {
123 if (dst_cmp(ent, dst)) {
131 /* allocate dsthash_ent, initialize dst, put in htable and lock it */
132 static struct dsthash_ent *
133 __dsthash_alloc_init(struct ipt_hashlimit_htable *ht, struct dsthash_dst *dst)
135 struct dsthash_ent *ent;
137 /* initialize hash with random val at the time we allocate
138 * the first hashtable entry */
140 get_random_bytes(&ht->rnd, 4);
143 atomic_read(&ht->count) >= ht->cfg.max) {
144 /* FIXME: do something. question is what.. */
147 "ipt_hashlimit: max count of %u reached\n",
152 ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
156 "ipt_hashlimit: can't allocate dsthash_ent\n");
160 atomic_inc(&ht->count);
162 ent->dst.dst_ip = dst->dst_ip;
163 ent->dst.dst_port = dst->dst_port;
164 ent->dst.src_ip = dst->src_ip;
165 ent->dst.src_port = dst->src_port;
167 hlist_add_head(&ent->node, &ht->hash[hash_dst(ht, dst)]);
173 __dsthash_free(struct ipt_hashlimit_htable *ht, struct dsthash_ent *ent)
175 hlist_del(&ent->node);
176 kmem_cache_free(hashlimit_cachep, ent);
177 atomic_dec(&ht->count);
179 static void htable_gc(unsigned long htlong);
181 static int htable_create(struct ipt_hashlimit_info *minfo)
185 struct ipt_hashlimit_htable *hinfo;
188 size = minfo->cfg.size;
190 size = (((num_physpages << PAGE_SHIFT) / 16384)
191 / sizeof(struct list_head));
192 if (num_physpages > (1024 * 1024 * 1024 / PAGE_SIZE))
197 /* FIXME: don't use vmalloc() here or anywhere else -HW */
198 hinfo = vmalloc(sizeof(struct ipt_hashlimit_htable)
199 + (sizeof(struct list_head) * size));
201 printk(KERN_ERR "ipt_hashlimit: Unable to create hashtable\n");
204 minfo->hinfo = hinfo;
206 /* copy match config into hashtable config */
207 memcpy(&hinfo->cfg, &minfo->cfg, sizeof(hinfo->cfg));
208 hinfo->cfg.size = size;
210 hinfo->cfg.max = 8 * hinfo->cfg.size;
211 else if (hinfo->cfg.max < hinfo->cfg.size)
212 hinfo->cfg.max = hinfo->cfg.size;
214 for (i = 0; i < hinfo->cfg.size; i++)
215 INIT_HLIST_HEAD(&hinfo->hash[i]);
217 atomic_set(&hinfo->count, 0);
218 atomic_set(&hinfo->use, 1);
220 spin_lock_init(&hinfo->lock);
221 hinfo->pde = create_proc_entry(minfo->name, 0, hashlimit_procdir);
226 hinfo->pde->proc_fops = &dl_file_ops;
227 hinfo->pde->data = hinfo;
229 init_timer(&hinfo->timer);
230 hinfo->timer.expires = jiffies + msecs_to_jiffies(hinfo->cfg.gc_interval);
231 hinfo->timer.data = (unsigned long )hinfo;
232 hinfo->timer.function = htable_gc;
233 add_timer(&hinfo->timer);
235 spin_lock_bh(&hashlimit_lock);
236 hlist_add_head(&hinfo->node, &hashlimit_htables);
237 spin_unlock_bh(&hashlimit_lock);
242 static int select_all(struct ipt_hashlimit_htable *ht, struct dsthash_ent *he)
247 static int select_gc(struct ipt_hashlimit_htable *ht, struct dsthash_ent *he)
249 return (jiffies >= he->expires);
252 static void htable_selective_cleanup(struct ipt_hashlimit_htable *ht,
253 int (*select)(struct ipt_hashlimit_htable *ht,
254 struct dsthash_ent *he))
258 IP_NF_ASSERT(ht->cfg.size && ht->cfg.max);
260 /* lock hash table and iterate over it */
261 spin_lock_bh(&ht->lock);
262 for (i = 0; i < ht->cfg.size; i++) {
263 struct dsthash_ent *dh;
264 struct hlist_node *pos, *n;
265 hlist_for_each_entry_safe(dh, pos, n, &ht->hash[i], node) {
266 if ((*select)(ht, dh))
267 __dsthash_free(ht, dh);
270 spin_unlock_bh(&ht->lock);
273 /* hash table garbage collector, run by timer */
274 static void htable_gc(unsigned long htlong)
276 struct ipt_hashlimit_htable *ht = (struct ipt_hashlimit_htable *)htlong;
278 htable_selective_cleanup(ht, select_gc);
280 /* re-add the timer accordingly */
281 ht->timer.expires = jiffies + msecs_to_jiffies(ht->cfg.gc_interval);
282 add_timer(&ht->timer);
285 static void htable_destroy(struct ipt_hashlimit_htable *hinfo)
287 /* remove timer, if it is pending */
288 if (timer_pending(&hinfo->timer))
289 del_timer(&hinfo->timer);
291 /* remove proc entry */
292 remove_proc_entry(hinfo->pde->name, hashlimit_procdir);
294 htable_selective_cleanup(hinfo, select_all);
298 static struct ipt_hashlimit_htable *htable_find_get(char *name)
300 struct ipt_hashlimit_htable *hinfo;
301 struct hlist_node *pos;
303 spin_lock_bh(&hashlimit_lock);
304 hlist_for_each_entry(hinfo, pos, &hashlimit_htables, node) {
305 if (!strcmp(name, hinfo->pde->name)) {
306 atomic_inc(&hinfo->use);
307 spin_unlock_bh(&hashlimit_lock);
311 spin_unlock_bh(&hashlimit_lock);
316 static void htable_put(struct ipt_hashlimit_htable *hinfo)
318 if (atomic_dec_and_test(&hinfo->use)) {
319 spin_lock_bh(&hashlimit_lock);
320 hlist_del(&hinfo->node);
321 spin_unlock_bh(&hashlimit_lock);
322 htable_destroy(hinfo);
327 /* The algorithm used is the Simple Token Bucket Filter (TBF)
328 * see net/sched/sch_tbf.c in the linux source tree
331 /* Rusty: This is my (non-mathematically-inclined) understanding of
332 this algorithm. The `average rate' in jiffies becomes your initial
333 amount of credit `credit' and the most credit you can ever have
334 `credit_cap'. The `peak rate' becomes the cost of passing the
337 `prev' tracks the last packet hit: you gain one credit per jiffy.
338 If you get credit balance more than this, the extra credit is
339 discarded. Every time the match passes, you lose `cost' credits;
340 if you don't have that many, the test fails.
342 See Alexey's formal explanation in net/sched/sch_tbf.c.
344 To get the maximum range, we multiply by this factor (ie. you get N
345 credits per jiffy). We want to allow a rate as low as 1 per day
346 (slowest userspace tool allows), which means
347 CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
349 #define MAX_CPJ (0xFFFFFFFF / (HZ*60*60*24))
351 /* Repeated shift and or gives us all 1s, final shift and add 1 gives
352 * us the power of 2 below the theoretical max, so GCC simply does a
354 #define _POW2_BELOW2(x) ((x)|((x)>>1))
355 #define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
356 #define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
357 #define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
358 #define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
359 #define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
361 #define CREDITS_PER_JIFFY POW2_BELOW32(MAX_CPJ)
363 /* Precision saver. */
364 static inline u_int32_t
365 user2credits(u_int32_t user)
367 /* If multiplying would overflow... */
368 if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY))
370 return (user / IPT_HASHLIMIT_SCALE) * HZ * CREDITS_PER_JIFFY;
372 return (user * HZ * CREDITS_PER_JIFFY) / IPT_HASHLIMIT_SCALE;
375 static inline void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now)
377 dh->rateinfo.credit += (now - xchg(&dh->rateinfo.prev, now))
379 if (dh->rateinfo.credit > dh->rateinfo.credit_cap)
380 dh->rateinfo.credit = dh->rateinfo.credit_cap;
383 static inline int get_ports(const struct sk_buff *skb, int offset,
389 sctp_sctphdr_t sctph;
392 /* Must not be a fragment. */
396 /* Must be big enough to read ports (both UDP and TCP have
397 them at the start). */
398 ptr_u = skb_header_pointer(skb, skb->nh.iph->ihl*4, 8, &hdr_u);
402 switch (skb->nh.iph->protocol) {
404 ports[0] = ptr_u->th.source;
405 ports[1] = ptr_u->th.dest;
408 ports[0] = ptr_u->uh.source;
409 ports[1] = ptr_u->uh.dest;
412 ports[0] = ptr_u->sctph.source;
413 ports[1] = ptr_u->sctph.dest;
416 /* all other protocols don't supprot per-port hash
418 ports[0] = ports[1] = 0;
427 hashlimit_match(const struct sk_buff *skb,
428 const struct net_device *in,
429 const struct net_device *out,
430 const void *matchinfo,
432 unsigned int protoff,
435 struct ipt_hashlimit_info *r =
436 ((struct ipt_hashlimit_info *)matchinfo)->u.master;
437 struct ipt_hashlimit_htable *hinfo = r->hinfo;
438 unsigned long now = jiffies;
439 struct dsthash_ent *dh;
440 struct dsthash_dst dst;
442 /* build 'dst' according to hinfo->cfg and current packet */
443 memset(&dst, 0, sizeof(dst));
444 if (hinfo->cfg.mode & IPT_HASHLIMIT_HASH_DIP)
445 dst.dst_ip = skb->nh.iph->daddr;
446 if (hinfo->cfg.mode & IPT_HASHLIMIT_HASH_SIP)
447 dst.src_ip = skb->nh.iph->saddr;
448 if (hinfo->cfg.mode & IPT_HASHLIMIT_HASH_DPT
449 ||hinfo->cfg.mode & IPT_HASHLIMIT_HASH_SPT) {
451 if (get_ports(skb, offset, ports)) {
452 /* We've been asked to examine this packet, and we
453 can't. Hence, no choice but to drop. */
457 if (hinfo->cfg.mode & IPT_HASHLIMIT_HASH_SPT)
458 dst.src_port = ports[0];
459 if (hinfo->cfg.mode & IPT_HASHLIMIT_HASH_DPT)
460 dst.dst_port = ports[1];
463 spin_lock_bh(&hinfo->lock);
464 dh = __dsthash_find(hinfo, &dst);
466 dh = __dsthash_alloc_init(hinfo, &dst);
469 /* enomem... don't match == DROP */
471 printk(KERN_ERR "%s: ENOMEM\n", __FUNCTION__);
472 spin_unlock_bh(&hinfo->lock);
476 dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
478 dh->rateinfo.prev = jiffies;
479 dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
481 dh->rateinfo.credit_cap = user2credits(hinfo->cfg.avg *
483 dh->rateinfo.cost = user2credits(hinfo->cfg.avg);
485 spin_unlock_bh(&hinfo->lock);
489 /* update expiration timeout */
490 dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
492 rateinfo_recalc(dh, now);
493 if (dh->rateinfo.credit >= dh->rateinfo.cost) {
494 /* We're underlimit. */
495 dh->rateinfo.credit -= dh->rateinfo.cost;
496 spin_unlock_bh(&hinfo->lock);
500 spin_unlock_bh(&hinfo->lock);
502 /* default case: we're overlimit, thus don't match */
507 hashlimit_checkentry(const char *tablename,
510 unsigned int matchsize,
511 unsigned int hook_mask)
513 struct ipt_hashlimit_info *r = matchinfo;
515 /* Check for overflow. */
516 if (r->cfg.burst == 0
517 || user2credits(r->cfg.avg * r->cfg.burst) <
518 user2credits(r->cfg.avg)) {
519 printk(KERN_ERR "ipt_hashlimit: Overflow, try lower: %u/%u\n",
520 r->cfg.avg, r->cfg.burst);
525 || r->cfg.mode > (IPT_HASHLIMIT_HASH_DPT
526 |IPT_HASHLIMIT_HASH_DIP
527 |IPT_HASHLIMIT_HASH_SIP
528 |IPT_HASHLIMIT_HASH_SPT))
531 if (!r->cfg.gc_interval)
537 /* This is the best we've got: We cannot release and re-grab lock,
538 * since checkentry() is called before ip_tables.c grabs ipt_mutex.
539 * We also cannot grab the hashtable spinlock, since htable_create will
540 * call vmalloc, and that can sleep. And we cannot just re-search
541 * the list of htable's in htable_create(), since then we would
542 * create duplicate proc files. -HW */
544 r->hinfo = htable_find_get(r->name);
545 if (!r->hinfo && (htable_create(r) != 0)) {
551 /* Ugly hack: For SMP, we only want to use one set */
558 hashlimit_destroy(void *matchinfo, unsigned int matchsize)
560 struct ipt_hashlimit_info *r = (struct ipt_hashlimit_info *) matchinfo;
562 htable_put(r->hinfo);
565 static struct ipt_match ipt_hashlimit = {
567 .match = hashlimit_match,
568 .matchsize = sizeof(struct ipt_hashlimit_info),
569 .checkentry = hashlimit_checkentry,
570 .destroy = hashlimit_destroy,
576 static void *dl_seq_start(struct seq_file *s, loff_t *pos)
578 struct proc_dir_entry *pde = s->private;
579 struct ipt_hashlimit_htable *htable = pde->data;
580 unsigned int *bucket;
582 spin_lock_bh(&htable->lock);
583 if (*pos >= htable->cfg.size)
586 bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
588 return ERR_PTR(-ENOMEM);
594 static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
596 struct proc_dir_entry *pde = s->private;
597 struct ipt_hashlimit_htable *htable = pde->data;
598 unsigned int *bucket = (unsigned int *)v;
601 if (*pos >= htable->cfg.size) {
608 static void dl_seq_stop(struct seq_file *s, void *v)
610 struct proc_dir_entry *pde = s->private;
611 struct ipt_hashlimit_htable *htable = pde->data;
612 unsigned int *bucket = (unsigned int *)v;
616 spin_unlock_bh(&htable->lock);
619 static inline int dl_seq_real_show(struct dsthash_ent *ent, struct seq_file *s)
621 /* recalculate to show accurate numbers */
622 rateinfo_recalc(ent, jiffies);
624 return seq_printf(s, "%ld %u.%u.%u.%u:%u->%u.%u.%u.%u:%u %u %u %u\n",
625 (long)(ent->expires - jiffies)/HZ,
626 NIPQUAD(ent->dst.src_ip), ntohs(ent->dst.src_port),
627 NIPQUAD(ent->dst.dst_ip), ntohs(ent->dst.dst_port),
628 ent->rateinfo.credit, ent->rateinfo.credit_cap,
632 static int dl_seq_show(struct seq_file *s, void *v)
634 struct proc_dir_entry *pde = s->private;
635 struct ipt_hashlimit_htable *htable = pde->data;
636 unsigned int *bucket = (unsigned int *)v;
637 struct dsthash_ent *ent;
638 struct hlist_node *pos;
640 if (!hlist_empty(&htable->hash[*bucket]))
641 hlist_for_each_entry(ent, pos, &htable->hash[*bucket], node) {
642 if (dl_seq_real_show(ent, s)) {
643 /* buffer was filled and unable to print that tuple */
651 static struct seq_operations dl_seq_ops = {
652 .start = dl_seq_start,
658 static int dl_proc_open(struct inode *inode, struct file *file)
660 int ret = seq_open(file, &dl_seq_ops);
663 struct seq_file *sf = file->private_data;
664 sf->private = PDE(inode);
669 static struct file_operations dl_file_ops = {
670 .owner = THIS_MODULE,
671 .open = dl_proc_open,
674 .release = seq_release
677 static int init_or_fini(int fini)
684 if (ipt_register_match(&ipt_hashlimit)) {
686 goto cleanup_nothing;
689 hashlimit_cachep = kmem_cache_create("ipt_hashlimit",
690 sizeof(struct dsthash_ent), 0,
692 if (!hashlimit_cachep) {
693 printk(KERN_ERR "Unable to create ipt_hashlimit slab cache\n");
695 goto cleanup_unreg_match;
698 hashlimit_procdir = proc_mkdir("ipt_hashlimit", proc_net);
699 if (!hashlimit_procdir) {
700 printk(KERN_ERR "Unable to create proc dir entry\n");
702 goto cleanup_free_slab;
708 remove_proc_entry("ipt_hashlimit", proc_net);
710 kmem_cache_destroy(hashlimit_cachep);
712 ipt_unregister_match(&ipt_hashlimit);
718 static int __init init(void)
720 return init_or_fini(0);
723 static void __exit fini(void)