1 /* Cluster IP hashmark target
2 * (C) 2003-2004 by Harald Welte <laforge@netfilter.org>
3 * based on ideas of Fabio Olive Leite <olive@unixforge.org>
4 *
5 * Development of this code funded by SuSE Linux AG, http://www.suse.com/
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 */
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13 #include <linux/module.h>
14 #include <linux/proc_fs.h>
15 #include <linux/jhash.h>
16 #include <linux/bitops.h>
17 #include <linux/skbuff.h>
18 #include <linux/slab.h>
19 #include <linux/ip.h>
20 #include <linux/tcp.h>
21 #include <linux/udp.h>
22 #include <linux/icmp.h>
23 #include <linux/if_arp.h>
24 #include <linux/seq_file.h>
25 #include <linux/netfilter_arp.h>
26 #include <linux/netfilter/x_tables.h>
27 #include <linux/netfilter_ipv4/ip_tables.h>
28 #include <linux/netfilter_ipv4/ipt_CLUSTERIP.h>
29 #include <net/netfilter/nf_conntrack.h>
30 #include <net/net_namespace.h>
31 #include <net/checksum.h>
32 #include <net/ip.h>
33
34 #define CLUSTERIP_VERSION "0.8"
35
36 MODULE_LICENSE("GPL");
37 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
38 MODULE_DESCRIPTION("Xtables: CLUSTERIP target");
39
40 struct clusterip_config {
41 struct list_head list; /* list of all configs */
42 atomic_t refcount; /* reference count */
43 atomic_t entries; /* number of entries/rules
44 * referencing us */
45
46 __be32 clusterip; /* the IP address */
47 u_int8_t clustermac[ETH_ALEN]; /* the MAC address */
48 struct net_device *dev; /* device */
49 u_int16_t num_total_nodes; /* total number of nodes */
50 unsigned long local_nodes; /* node number array */
51
52 #ifdef CONFIG_PROC_FS
53 struct proc_dir_entry *pde; /* proc dir entry */
54 #endif
55 enum clusterip_hashmode hash_mode; /* which hashing mode */
56 u_int32_t hash_initval; /* hash initialization */
57 struct rcu_head rcu;
58 };
59
60 static LIST_HEAD(clusterip_configs);
61
62 /* clusterip_lock protects the clusterip_configs list */
63 static DEFINE_SPINLOCK(clusterip_lock);
64
65 #ifdef CONFIG_PROC_FS
66 static const struct file_operations clusterip_proc_fops;
67 static struct proc_dir_entry *clusterip_procdir;
68 #endif
69
70 static inline void
71 clusterip_config_get(struct clusterip_config *c)
72 {
73 atomic_inc(&c->refcount);
74 }
75
76
77 static void clusterip_config_rcu_free(struct rcu_head *head)
78 {
79 kfree(container_of(head, struct clusterip_config, rcu));
80 }
81
82 static inline void
83 clusterip_config_put(struct clusterip_config *c)
84 {
85 if (atomic_dec_and_test(&c->refcount))
86 call_rcu_bh(&c->rcu, clusterip_config_rcu_free);
87 }
88
89 /* decrease the count of entries using/referencing this config. If last
90 * entry(rule) is removed, remove the config from lists, but don't free it
91 * yet, since proc-files could still be holding references */
92 static inline void
93 clusterip_config_entry_put(struct clusterip_config *c)
94 {
95 local_bh_disable();
96 if (atomic_dec_and_lock(&c->entries, &clusterip_lock)) {
97 list_del_rcu(&c->list);
98 spin_unlock(&clusterip_lock);
99 local_bh_enable();
100
101 dev_mc_del(c->dev, c->clustermac);
102 dev_put(c->dev);
103
104 /* In case anyone still accesses the file, the open/close
105 * functions are also incrementing the refcount on their own,
106 * so it's safe to remove the entry even if it's in use. */
107 #ifdef CONFIG_PROC_FS
108 proc_remove(c->pde);
109 #endif
110 return;
111 }
112 local_bh_enable();
113 }
114
115 static struct clusterip_config *
116 __clusterip_config_find(__be32 clusterip)
117 {
118 struct clusterip_config *c;
119
120 list_for_each_entry_rcu(c, &clusterip_configs, list) {
121 if (c->clusterip == clusterip)
122 return c;
123 }
124
125 return NULL;
126 }
127
128 static inline struct clusterip_config *
129 clusterip_config_find_get(__be32 clusterip, int entry)
130 {
131 struct clusterip_config *c;
132
133 rcu_read_lock_bh();
134 c = __clusterip_config_find(clusterip);
135 if (c) {
136 if (unlikely(!atomic_inc_not_zero(&c->refcount)))
137 c = NULL;
138 else if (entry)
139 atomic_inc(&c->entries);
140 }
141 rcu_read_unlock_bh();
142
143 return c;
144 }
145
146 static void
147 clusterip_config_init_nodelist(struct clusterip_config *c,
148 const struct ipt_clusterip_tgt_info *i)
149 {
150 int n;
151
152 for (n = 0; n < i->num_local_nodes; n++)
153 set_bit(i->local_nodes[n] - 1, &c->local_nodes);
154 }
155
156 static struct clusterip_config *
157 clusterip_config_init(const struct ipt_clusterip_tgt_info *i, __be32 ip,
158 struct net_device *dev)
159 {
160 struct clusterip_config *c;
161
162 c = kzalloc(sizeof(*c), GFP_ATOMIC);
163 if (!c)
164 return NULL;
165
166 c->dev = dev;
167 c->clusterip = ip;
168 memcpy(&c->clustermac, &i->clustermac, ETH_ALEN);
169 c->num_total_nodes = i->num_total_nodes;
170 clusterip_config_init_nodelist(c, i);
171 c->hash_mode = i->hash_mode;
172 c->hash_initval = i->hash_initval;
173 atomic_set(&c->refcount, 1);
174 atomic_set(&c->entries, 1);
175
176 #ifdef CONFIG_PROC_FS
177 {
178 char buffer[16];
179
180 /* create proc dir entry */
181 sprintf(buffer, "%pI4", &ip);
182 c->pde = proc_create_data(buffer, S_IWUSR|S_IRUSR,
183 clusterip_procdir,
184 &clusterip_proc_fops, c);
185 if (!c->pde) {
186 kfree(c);
187 return NULL;
188 }
189 }
190 #endif
191
192 spin_lock_bh(&clusterip_lock);
193 list_add_rcu(&c->list, &clusterip_configs);
194 spin_unlock_bh(&clusterip_lock);
195
196 return c;
197 }
198
199 #ifdef CONFIG_PROC_FS
200 static int
201 clusterip_add_node(struct clusterip_config *c, u_int16_t nodenum)
202 {
203
204 if (nodenum == 0 ||
205 nodenum > c->num_total_nodes)
206 return 1;
207
208 /* check if we already have this number in our bitfield */
209 if (test_and_set_bit(nodenum - 1, &c->local_nodes))
210 return 1;
211
212 return 0;
213 }
214
215 static bool
216 clusterip_del_node(struct clusterip_config *c, u_int16_t nodenum)
217 {
218 if (nodenum == 0 ||
219 nodenum > c->num_total_nodes)
220 return true;
221
222 if (test_and_clear_bit(nodenum - 1, &c->local_nodes))
223 return false;
224
225 return true;
226 }
227 #endif
228
229 static inline u_int32_t
230 clusterip_hashfn(const struct sk_buff *skb,
231 const struct clusterip_config *config)
232 {
233 const struct iphdr *iph = ip_hdr(skb);
234 unsigned long hashval;
235 u_int16_t sport = 0, dport = 0;
236 int poff;
237
238 poff = proto_ports_offset(iph->protocol);
239 if (poff >= 0) {
240 const u_int16_t *ports;
241 u16 _ports[2];
242
243 ports = skb_header_pointer(skb, iph->ihl * 4 + poff, 4, _ports);
244 if (ports) {
245 sport = ports[0];
246 dport = ports[1];
247 }
248 } else {
249 net_info_ratelimited("unknown protocol %u\n", iph->protocol);
250 }
251
252 switch (config->hash_mode) {
253 case CLUSTERIP_HASHMODE_SIP:
254 hashval = jhash_1word(ntohl(iph->saddr),
255 config->hash_initval);
256 break;
257 case CLUSTERIP_HASHMODE_SIP_SPT:
258 hashval = jhash_2words(ntohl(iph->saddr), sport,
259 config->hash_initval);
260 break;
261 case CLUSTERIP_HASHMODE_SIP_SPT_DPT:
262 hashval = jhash_3words(ntohl(iph->saddr), sport, dport,
263 config->hash_initval);
264 break;
265 default:
266 /* to make gcc happy */
267 hashval = 0;
268 /* This cannot happen, unless the check function wasn't called
269 * at rule load time */
270 pr_info("unknown mode %u\n", config->hash_mode);
271 BUG();
272 break;
273 }
274
275 /* node numbers are 1..n, not 0..n */
276 return (((u64)hashval * config->num_total_nodes) >> 32) + 1;
277 }
278
279 static inline int
280 clusterip_responsible(const struct clusterip_config *config, u_int32_t hash)
281 {
282 return test_bit(hash - 1, &config->local_nodes);
283 }
284
285 /***********************************************************************
286 * IPTABLES TARGET
287 ***********************************************************************/
288
289 static unsigned int
290 clusterip_tg(struct sk_buff *skb, const struct xt_action_param *par)
291 {
292 const struct ipt_clusterip_tgt_info *cipinfo = par->targinfo;
293 struct nf_conn *ct;
294 enum ip_conntrack_info ctinfo;
295 u_int32_t hash;
296
297 /* don't need to clusterip_config_get() here, since refcount
298 * is only decremented by destroy() - and ip_tables guarantees
299 * that the ->target() function isn't called after ->destroy() */
300
301 ct = nf_ct_get(skb, &ctinfo);
302 if (ct == NULL)
303 return NF_DROP;
304
305 /* special case: ICMP error handling. conntrack distinguishes between
306 * error messages (RELATED) and information requests (see below) */
307 if (ip_hdr(skb)->protocol == IPPROTO_ICMP &&
308 (ctinfo == IP_CT_RELATED ||
309 ctinfo == IP_CT_RELATED_REPLY))
310 return XT_CONTINUE;
311
312 /* ip_conntrack_icmp guarantees us that we only have ICMP_ECHO,
313 * TIMESTAMP, INFO_REQUEST or ADDRESS type icmp packets from here
314 * on, which all have an ID field [relevant for hashing]. */
315
316 hash = clusterip_hashfn(skb, cipinfo->config);
317
318 switch (ctinfo) {
319 case IP_CT_NEW:
320 ct->mark = hash;
321 break;
322 case IP_CT_RELATED:
323 case IP_CT_RELATED_REPLY:
324 /* FIXME: we don't handle expectations at the moment.
325 * They can arrive on a different node than
326 * the master connection (e.g. FTP passive mode) */
327 case IP_CT_ESTABLISHED:
328 case IP_CT_ESTABLISHED_REPLY:
329 break;
330 default: /* Prevent gcc warnings */
331 break;
332 }
333
334 #ifdef DEBUG
335 nf_ct_dump_tuple_ip(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
336 #endif
337 pr_debug("hash=%u ct_hash=%u ", hash, ct->mark);
338 if (!clusterip_responsible(cipinfo->config, hash)) {
339 pr_debug("not responsible\n");
340 return NF_DROP;
341 }
342 pr_debug("responsible\n");
343
344 /* despite being received via linklayer multicast, this is
345 * actually a unicast IP packet. TCP doesn't like PACKET_MULTICAST */
346 skb->pkt_type = PACKET_HOST;
347
348 return XT_CONTINUE;
349 }
350
351 static int clusterip_tg_check(const struct xt_tgchk_param *par)
352 {
353 struct ipt_clusterip_tgt_info *cipinfo = par->targinfo;
354 const struct ipt_entry *e = par->entryinfo;
355 struct clusterip_config *config;
356 int ret;
357
358 if (cipinfo->hash_mode != CLUSTERIP_HASHMODE_SIP &&
359 cipinfo->hash_mode != CLUSTERIP_HASHMODE_SIP_SPT &&
360 cipinfo->hash_mode != CLUSTERIP_HASHMODE_SIP_SPT_DPT) {
361 pr_info("unknown mode %u\n", cipinfo->hash_mode);
362 return -EINVAL;
363
364 }
365 if (e->ip.dmsk.s_addr != htonl(0xffffffff) ||
366 e->ip.dst.s_addr == 0) {
367 pr_info("Please specify destination IP\n");
368 return -EINVAL;
369 }
370
371 /* FIXME: further sanity checks */
372
373 config = clusterip_config_find_get(e->ip.dst.s_addr, 1);
374 if (!config) {
375 if (!(cipinfo->flags & CLUSTERIP_FLAG_NEW)) {
376 pr_info("no config found for %pI4, need 'new'\n",
377 &e->ip.dst.s_addr);
378 return -EINVAL;
379 } else {
380 struct net_device *dev;
381
382 if (e->ip.iniface[0] == '\0') {
383 pr_info("Please specify an interface name\n");
384 return -EINVAL;
385 }
386
387 dev = dev_get_by_name(&init_net, e->ip.iniface);
388 if (!dev) {
389 pr_info("no such interface %s\n",
390 e->ip.iniface);
391 return -ENOENT;
392 }
393
394 config = clusterip_config_init(cipinfo,
395 e->ip.dst.s_addr, dev);
396 if (!config) {
397 dev_put(dev);
398 return -ENOMEM;
399 }
400 dev_mc_add(config->dev, config->clustermac);
401 }
402 }
403 cipinfo->config = config;
404
405 ret = nf_ct_l3proto_try_module_get(par->family);
406 if (ret < 0)
407 pr_info("cannot load conntrack support for proto=%u\n",
408 par->family);
409 return ret;
410 }
411
412 /* drop reference count of cluster config when rule is deleted */
413 static void clusterip_tg_destroy(const struct xt_tgdtor_param *par)
414 {
415 const struct ipt_clusterip_tgt_info *cipinfo = par->targinfo;
416
417 /* if no more entries are referencing the config, remove it
418 * from the list and destroy the proc entry */
419 clusterip_config_entry_put(cipinfo->config);
420
421 clusterip_config_put(cipinfo->config);
422
423 nf_ct_l3proto_module_put(par->family);
424 }
425
426 #ifdef CONFIG_COMPAT
427 struct compat_ipt_clusterip_tgt_info
428 {
429 u_int32_t flags;
430 u_int8_t clustermac[6];
431 u_int16_t num_total_nodes;
432 u_int16_t num_local_nodes;
433 u_int16_t local_nodes[CLUSTERIP_MAX_NODES];
434 u_int32_t hash_mode;
435 u_int32_t hash_initval;
436 compat_uptr_t config;
437 };
438 #endif /* CONFIG_COMPAT */
439
440 static struct xt_target clusterip_tg_reg __read_mostly = {
441 .name = "CLUSTERIP",
442 .family = NFPROTO_IPV4,
443 .target = clusterip_tg,
444 .checkentry = clusterip_tg_check,
445 .destroy = clusterip_tg_destroy,
446 .targetsize = sizeof(struct ipt_clusterip_tgt_info),
447 #ifdef CONFIG_COMPAT
448 .compatsize = sizeof(struct compat_ipt_clusterip_tgt_info),
449 #endif /* CONFIG_COMPAT */
450 .me = THIS_MODULE
451 };
452
453
454 /***********************************************************************
455 * ARP MANGLING CODE
456 ***********************************************************************/
457
458 /* hardcoded for 48bit ethernet and 32bit ipv4 addresses */
459 struct arp_payload {
460 u_int8_t src_hw[ETH_ALEN];
461 __be32 src_ip;
462 u_int8_t dst_hw[ETH_ALEN];
463 __be32 dst_ip;
464 } __packed;
465
466 #ifdef DEBUG
467 static void arp_print(struct arp_payload *payload)
468 {
469 #define HBUFFERLEN 30
470 char hbuffer[HBUFFERLEN];
471 int j,k;
472
473 for (k=0, j=0; k < HBUFFERLEN-3 && j < ETH_ALEN; j++) {
474 hbuffer[k++] = hex_asc_hi(payload->src_hw[j]);
475 hbuffer[k++] = hex_asc_lo(payload->src_hw[j]);
476 hbuffer[k++]=':';
477 }
478 hbuffer[--k]='\0';
479
480 pr_debug("src %pI4@%s, dst %pI4\n",
481 &payload->src_ip, hbuffer, &payload->dst_ip);
482 }
483 #endif
484
485 static unsigned int
486 arp_mangle(unsigned int hook,
487 struct sk_buff *skb,
488 const struct net_device *in,
489 const struct net_device *out,
490 int (*okfn)(struct sk_buff *))
491 {
492 struct arphdr *arp = arp_hdr(skb);
493 struct arp_payload *payload;
494 struct clusterip_config *c;
495
496 /* we don't care about non-ethernet and non-ipv4 ARP */
497 if (arp->ar_hrd != htons(ARPHRD_ETHER) ||
498 arp->ar_pro != htons(ETH_P_IP) ||
499 arp->ar_pln != 4 || arp->ar_hln != ETH_ALEN)
500 return NF_ACCEPT;
501
502 /* we only want to mangle arp requests and replies */
503 if (arp->ar_op != htons(ARPOP_REPLY) &&
504 arp->ar_op != htons(ARPOP_REQUEST))
505 return NF_ACCEPT;
506
507 payload = (void *)(arp+1);
508
509 /* if there is no clusterip configuration for the arp reply's
510 * source ip, we don't want to mangle it */
511 c = clusterip_config_find_get(payload->src_ip, 0);
512 if (!c)
513 return NF_ACCEPT;
514
515 /* normally the linux kernel always replies to arp queries of
516 * addresses on different interfacs. However, in the CLUSTERIP case
517 * this wouldn't work, since we didn't subscribe the mcast group on
518 * other interfaces */
519 if (c->dev != out) {
520 pr_debug("not mangling arp reply on different "
521 "interface: cip'%s'-skb'%s'\n",
522 c->dev->name, out->name);
523 clusterip_config_put(c);
524 return NF_ACCEPT;
525 }
526
527 /* mangle reply hardware address */
528 memcpy(payload->src_hw, c->clustermac, arp->ar_hln);
529
530 #ifdef DEBUG
531 pr_debug("mangled arp reply: ");
532 arp_print(payload);
533 #endif
534
535 clusterip_config_put(c);
536
537 return NF_ACCEPT;
538 }
539
540 static struct nf_hook_ops cip_arp_ops __read_mostly = {
541 .hook = arp_mangle,
542 .pf = NFPROTO_ARP,
543 .hooknum = NF_ARP_OUT,
544 .priority = -1
545 };
546
547 /***********************************************************************
548 * PROC DIR HANDLING
549 ***********************************************************************/
550
551 #ifdef CONFIG_PROC_FS
552
553 struct clusterip_seq_position {
554 unsigned int pos; /* position */
555 unsigned int weight; /* number of bits set == size */
556 unsigned int bit; /* current bit */
557 unsigned long val; /* current value */
558 };
559
560 static void *clusterip_seq_start(struct seq_file *s, loff_t *pos)
561 {
562 struct clusterip_config *c = s->private;
563 unsigned int weight;
564 u_int32_t local_nodes;
565 struct clusterip_seq_position *idx;
566
567 /* FIXME: possible race */
568 local_nodes = c->local_nodes;
569 weight = hweight32(local_nodes);
570 if (*pos >= weight)
571 return NULL;
572
573 idx = kmalloc(sizeof(struct clusterip_seq_position), GFP_KERNEL);
574 if (!idx)
575 return ERR_PTR(-ENOMEM);
576
577 idx->pos = *pos;
578 idx->weight = weight;
579 idx->bit = ffs(local_nodes);
580 idx->val = local_nodes;
581 clear_bit(idx->bit - 1, &idx->val);
582
583 return idx;
584 }
585
586 static void *clusterip_seq_next(struct seq_file *s, void *v, loff_t *pos)
587 {
588 struct clusterip_seq_position *idx = v;
589
590 *pos = ++idx->pos;
591 if (*pos >= idx->weight) {
592 kfree(v);
593 return NULL;
594 }
595 idx->bit = ffs(idx->val);
596 clear_bit(idx->bit - 1, &idx->val);
597 return idx;
598 }
599
600 static void clusterip_seq_stop(struct seq_file *s, void *v)
601 {
602 if (!IS_ERR(v))
603 kfree(v);
604 }
605
606 static int clusterip_seq_show(struct seq_file *s, void *v)
607 {
608 struct clusterip_seq_position *idx = v;
609
610 if (idx->pos != 0)
611 seq_putc(s, ',');
612
613 seq_printf(s, "%u", idx->bit);
614
615 if (idx->pos == idx->weight - 1)
616 seq_putc(s, '\n');
617
618 return 0;
619 }
620
621 static const struct seq_operations clusterip_seq_ops = {
622 .start = clusterip_seq_start,
623 .next = clusterip_seq_next,
624 .stop = clusterip_seq_stop,
625 .show = clusterip_seq_show,
626 };
627
628 static int clusterip_proc_open(struct inode *inode, struct file *file)
629 {
630 int ret = seq_open(file, &clusterip_seq_ops);
631
632 if (!ret) {
633 struct seq_file *sf = file->private_data;
634 struct clusterip_config *c = PDE_DATA(inode);
635
636 sf->private = c;
637
638 clusterip_config_get(c);
639 }
640
641 return ret;
642 }
643
644 static int clusterip_proc_release(struct inode *inode, struct file *file)
645 {
646 struct clusterip_config *c = PDE_DATA(inode);
647 int ret;
648
649 ret = seq_release(inode, file);
650
651 if (!ret)
652 clusterip_config_put(c);
653
654 return ret;
655 }
656
657 static ssize_t clusterip_proc_write(struct file *file, const char __user *input,
658 size_t size, loff_t *ofs)
659 {
660 struct clusterip_config *c = PDE_DATA(file_inode(file));
661 #define PROC_WRITELEN 10
662 char buffer[PROC_WRITELEN+1];
663 unsigned long nodenum;
664 int rc;
665
666 if (size > PROC_WRITELEN)
667 return -EIO;
668 if (copy_from_user(buffer, input, size))
669 return -EFAULT;
670 buffer[size] = 0;
671
672 if (*buffer == '+') {
673 rc = kstrtoul(buffer+1, 10, &nodenum);
674 if (rc)
675 return rc;
676 if (clusterip_add_node(c, nodenum))
677 return -ENOMEM;
678 } else if (*buffer == '-') {
679 rc = kstrtoul(buffer+1, 10, &nodenum);
680 if (rc)
681 return rc;
682 if (clusterip_del_node(c, nodenum))
683 return -ENOENT;
684 } else
685 return -EIO;
686
687 return size;
688 }
689
690 static const struct file_operations clusterip_proc_fops = {
691 .owner = THIS_MODULE,
692 .open = clusterip_proc_open,
693 .read = seq_read,
694 .write = clusterip_proc_write,
695 .llseek = seq_lseek,
696 .release = clusterip_proc_release,
697 };
698
699 #endif /* CONFIG_PROC_FS */
700
701 static int __init clusterip_tg_init(void)
702 {
703 int ret;
704
705 ret = xt_register_target(&clusterip_tg_reg);
706 if (ret < 0)
707 return ret;
708
709 ret = nf_register_hook(&cip_arp_ops);
710 if (ret < 0)
711 goto cleanup_target;
712
713 #ifdef CONFIG_PROC_FS
714 clusterip_procdir = proc_mkdir("ipt_CLUSTERIP", init_net.proc_net);
715 if (!clusterip_procdir) {
716 pr_err("Unable to proc dir entry\n");
717 ret = -ENOMEM;
718 goto cleanup_hook;
719 }
720 #endif /* CONFIG_PROC_FS */
721
722 pr_info("ClusterIP Version %s loaded successfully\n",
723 CLUSTERIP_VERSION);
724 return 0;
725
726 #ifdef CONFIG_PROC_FS
727 cleanup_hook:
728 nf_unregister_hook(&cip_arp_ops);
729 #endif /* CONFIG_PROC_FS */
730 cleanup_target:
731 xt_unregister_target(&clusterip_tg_reg);
732 return ret;
733 }
734
735 static void __exit clusterip_tg_exit(void)
736 {
737 pr_info("ClusterIP Version %s unloading\n", CLUSTERIP_VERSION);
738 #ifdef CONFIG_PROC_FS
739 proc_remove(clusterip_procdir);
740 #endif
741 nf_unregister_hook(&cip_arp_ops);
742 xt_unregister_target(&clusterip_tg_reg);
743
744 /* Wait for completion of call_rcu_bh()'s (clusterip_config_rcu_free) */
745 rcu_barrier_bh();
746 }
747
748 module_init(clusterip_tg_init);
749 module_exit(clusterip_tg_exit);
750
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