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Linux/net/ipv4/netfilter/ipt_CLUSTERIP.c

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  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                 remove_proc_entry(c->pde->name, c->pde->parent);
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                         if (unlikely(!atomic_inc_not_zero(&c->entries))) {
140                                 clusterip_config_put(c);
141                                 c = NULL;
142                         }
143                 }
144         }
145         rcu_read_unlock_bh();
146 
147         return c;
148 }
149 
150 static void
151 clusterip_config_init_nodelist(struct clusterip_config *c,
152                                const struct ipt_clusterip_tgt_info *i)
153 {
154         int n;
155 
156         for (n = 0; n < i->num_local_nodes; n++)
157                 set_bit(i->local_nodes[n] - 1, &c->local_nodes);
158 }
159 
160 static struct clusterip_config *
161 clusterip_config_init(const struct ipt_clusterip_tgt_info *i, __be32 ip,
162                         struct net_device *dev)
163 {
164         struct clusterip_config *c;
165 
166         c = kzalloc(sizeof(*c), GFP_ATOMIC);
167         if (!c)
168                 return NULL;
169 
170         c->dev = dev;
171         c->clusterip = ip;
172         memcpy(&c->clustermac, &i->clustermac, ETH_ALEN);
173         c->num_total_nodes = i->num_total_nodes;
174         clusterip_config_init_nodelist(c, i);
175         c->hash_mode = i->hash_mode;
176         c->hash_initval = i->hash_initval;
177         atomic_set(&c->refcount, 1);
178         atomic_set(&c->entries, 1);
179 
180 #ifdef CONFIG_PROC_FS
181         {
182                 char buffer[16];
183 
184                 /* create proc dir entry */
185                 sprintf(buffer, "%pI4", &ip);
186                 c->pde = proc_create_data(buffer, S_IWUSR|S_IRUSR,
187                                           clusterip_procdir,
188                                           &clusterip_proc_fops, c);
189                 if (!c->pde) {
190                         kfree(c);
191                         return NULL;
192                 }
193         }
194 #endif
195 
196         spin_lock_bh(&clusterip_lock);
197         list_add_rcu(&c->list, &clusterip_configs);
198         spin_unlock_bh(&clusterip_lock);
199 
200         return c;
201 }
202 
203 #ifdef CONFIG_PROC_FS
204 static int
205 clusterip_add_node(struct clusterip_config *c, u_int16_t nodenum)
206 {
207 
208         if (nodenum == 0 ||
209             nodenum > c->num_total_nodes)
210                 return 1;
211 
212         /* check if we already have this number in our bitfield */
213         if (test_and_set_bit(nodenum - 1, &c->local_nodes))
214                 return 1;
215 
216         return 0;
217 }
218 
219 static bool
220 clusterip_del_node(struct clusterip_config *c, u_int16_t nodenum)
221 {
222         if (nodenum == 0 ||
223             nodenum > c->num_total_nodes)
224                 return true;
225 
226         if (test_and_clear_bit(nodenum - 1, &c->local_nodes))
227                 return false;
228 
229         return true;
230 }
231 #endif
232 
233 static inline u_int32_t
234 clusterip_hashfn(const struct sk_buff *skb,
235                  const struct clusterip_config *config)
236 {
237         const struct iphdr *iph = ip_hdr(skb);
238         unsigned long hashval;
239         u_int16_t sport = 0, dport = 0;
240         int poff;
241 
242         poff = proto_ports_offset(iph->protocol);
243         if (poff >= 0) {
244                 const u_int16_t *ports;
245                 u16 _ports[2];
246 
247                 ports = skb_header_pointer(skb, iph->ihl * 4 + poff, 4, _ports);
248                 if (ports) {
249                         sport = ports[0];
250                         dport = ports[1];
251                 }
252         } else {
253                 if (net_ratelimit())
254                         pr_info("unknown protocol %u\n", iph->protocol);
255         }
256 
257         switch (config->hash_mode) {
258         case CLUSTERIP_HASHMODE_SIP:
259                 hashval = jhash_1word(ntohl(iph->saddr),
260                                       config->hash_initval);
261                 break;
262         case CLUSTERIP_HASHMODE_SIP_SPT:
263                 hashval = jhash_2words(ntohl(iph->saddr), sport,
264                                        config->hash_initval);
265                 break;
266         case CLUSTERIP_HASHMODE_SIP_SPT_DPT:
267                 hashval = jhash_3words(ntohl(iph->saddr), sport, dport,
268                                        config->hash_initval);
269                 break;
270         default:
271                 /* to make gcc happy */
272                 hashval = 0;
273                 /* This cannot happen, unless the check function wasn't called
274                  * at rule load time */
275                 pr_info("unknown mode %u\n", config->hash_mode);
276                 BUG();
277                 break;
278         }
279 
280         /* node numbers are 1..n, not 0..n */
281         return (((u64)hashval * config->num_total_nodes) >> 32) + 1;
282 }
283 
284 static inline int
285 clusterip_responsible(const struct clusterip_config *config, u_int32_t hash)
286 {
287         return test_bit(hash - 1, &config->local_nodes);
288 }
289 
290 /***********************************************************************
291  * IPTABLES TARGET
292  ***********************************************************************/
293 
294 static unsigned int
295 clusterip_tg(struct sk_buff *skb, const struct xt_action_param *par)
296 {
297         const struct ipt_clusterip_tgt_info *cipinfo = par->targinfo;
298         struct nf_conn *ct;
299         enum ip_conntrack_info ctinfo;
300         u_int32_t hash;
301 
302         /* don't need to clusterip_config_get() here, since refcount
303          * is only decremented by destroy() - and ip_tables guarantees
304          * that the ->target() function isn't called after ->destroy() */
305 
306         ct = nf_ct_get(skb, &ctinfo);
307         if (ct == NULL)
308                 return NF_DROP;
309 
310         /* special case: ICMP error handling. conntrack distinguishes between
311          * error messages (RELATED) and information requests (see below) */
312         if (ip_hdr(skb)->protocol == IPPROTO_ICMP &&
313             (ctinfo == IP_CT_RELATED ||
314              ctinfo == IP_CT_RELATED_REPLY))
315                 return XT_CONTINUE;
316 
317         /* ip_conntrack_icmp guarantees us that we only have ICMP_ECHO,
318          * TIMESTAMP, INFO_REQUEST or ADDRESS type icmp packets from here
319          * on, which all have an ID field [relevant for hashing]. */
320 
321         hash = clusterip_hashfn(skb, cipinfo->config);
322 
323         switch (ctinfo) {
324         case IP_CT_NEW:
325                 ct->mark = hash;
326                 break;
327         case IP_CT_RELATED:
328         case IP_CT_RELATED_REPLY:
329                 /* FIXME: we don't handle expectations at the moment.
330                  * They can arrive on a different node than
331                  * the master connection (e.g. FTP passive mode) */
332         case IP_CT_ESTABLISHED:
333         case IP_CT_ESTABLISHED_REPLY:
334                 break;
335         default:                        /* Prevent gcc warnings */
336                 break;
337         }
338 
339 #ifdef DEBUG
340         nf_ct_dump_tuple_ip(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
341 #endif
342         pr_debug("hash=%u ct_hash=%u ", hash, ct->mark);
343         if (!clusterip_responsible(cipinfo->config, hash)) {
344                 pr_debug("not responsible\n");
345                 return NF_DROP;
346         }
347         pr_debug("responsible\n");
348 
349         /* despite being received via linklayer multicast, this is
350          * actually a unicast IP packet. TCP doesn't like PACKET_MULTICAST */
351         skb->pkt_type = PACKET_HOST;
352 
353         return XT_CONTINUE;
354 }
355 
356 static int clusterip_tg_check(const struct xt_tgchk_param *par)
357 {
358         struct ipt_clusterip_tgt_info *cipinfo = par->targinfo;
359         const struct ipt_entry *e = par->entryinfo;
360         struct clusterip_config *config;
361         int ret, i;
362 
363         if (cipinfo->hash_mode != CLUSTERIP_HASHMODE_SIP &&
364             cipinfo->hash_mode != CLUSTERIP_HASHMODE_SIP_SPT &&
365             cipinfo->hash_mode != CLUSTERIP_HASHMODE_SIP_SPT_DPT) {
366                 pr_info("unknown mode %u\n", cipinfo->hash_mode);
367                 return -EINVAL;
368 
369         }
370         if (e->ip.dmsk.s_addr != htonl(0xffffffff) ||
371             e->ip.dst.s_addr == 0) {
372                 pr_info("Please specify destination IP\n");
373                 return -EINVAL;
374         }
375         if (cipinfo->num_local_nodes > ARRAY_SIZE(cipinfo->local_nodes)) {
376                 pr_info("bad num_local_nodes %u\n", cipinfo->num_local_nodes);
377                 return -EINVAL;
378         }
379         for (i = 0; i < cipinfo->num_local_nodes; i++) {
380                 if (cipinfo->local_nodes[i] - 1 >=
381                     sizeof(config->local_nodes) * 8) {
382                         pr_info("bad local_nodes[%d] %u\n",
383                                 i, cipinfo->local_nodes[i]);
384                         return -EINVAL;
385                 }
386         }
387 
388         config = clusterip_config_find_get(e->ip.dst.s_addr, 1);
389         if (!config) {
390                 if (!(cipinfo->flags & CLUSTERIP_FLAG_NEW)) {
391                         pr_info("no config found for %pI4, need 'new'\n",
392                                 &e->ip.dst.s_addr);
393                         return -EINVAL;
394                 } else {
395                         struct net_device *dev;
396 
397                         if (e->ip.iniface[0] == '\0') {
398                                 pr_info("Please specify an interface name\n");
399                                 return -EINVAL;
400                         }
401 
402                         dev = dev_get_by_name(&init_net, e->ip.iniface);
403                         if (!dev) {
404                                 pr_info("no such interface %s\n",
405                                         e->ip.iniface);
406                                 return -ENOENT;
407                         }
408 
409                         config = clusterip_config_init(cipinfo,
410                                                         e->ip.dst.s_addr, dev);
411                         if (!config) {
412                                 dev_put(dev);
413                                 return -ENOMEM;
414                         }
415                         dev_mc_add(config->dev, config->clustermac);
416                 }
417         }
418         cipinfo->config = config;
419 
420         ret = nf_ct_l3proto_try_module_get(par->family);
421         if (ret < 0)
422                 pr_info("cannot load conntrack support for proto=%u\n",
423                         par->family);
424         return ret;
425 }
426 
427 /* drop reference count of cluster config when rule is deleted */
428 static void clusterip_tg_destroy(const struct xt_tgdtor_param *par)
429 {
430         const struct ipt_clusterip_tgt_info *cipinfo = par->targinfo;
431 
432         /* if no more entries are referencing the config, remove it
433          * from the list and destroy the proc entry */
434         clusterip_config_entry_put(cipinfo->config);
435 
436         clusterip_config_put(cipinfo->config);
437 
438         nf_ct_l3proto_module_put(par->family);
439 }
440 
441 #ifdef CONFIG_COMPAT
442 struct compat_ipt_clusterip_tgt_info
443 {
444         u_int32_t       flags;
445         u_int8_t        clustermac[6];
446         u_int16_t       num_total_nodes;
447         u_int16_t       num_local_nodes;
448         u_int16_t       local_nodes[CLUSTERIP_MAX_NODES];
449         u_int32_t       hash_mode;
450         u_int32_t       hash_initval;
451         compat_uptr_t   config;
452 };
453 #endif /* CONFIG_COMPAT */
454 
455 static struct xt_target clusterip_tg_reg __read_mostly = {
456         .name           = "CLUSTERIP",
457         .family         = NFPROTO_IPV4,
458         .target         = clusterip_tg,
459         .checkentry     = clusterip_tg_check,
460         .destroy        = clusterip_tg_destroy,
461         .targetsize     = sizeof(struct ipt_clusterip_tgt_info),
462 #ifdef CONFIG_COMPAT
463         .compatsize     = sizeof(struct compat_ipt_clusterip_tgt_info),
464 #endif /* CONFIG_COMPAT */
465         .me             = THIS_MODULE
466 };
467 
468 
469 /***********************************************************************
470  * ARP MANGLING CODE
471  ***********************************************************************/
472 
473 /* hardcoded for 48bit ethernet and 32bit ipv4 addresses */
474 struct arp_payload {
475         u_int8_t src_hw[ETH_ALEN];
476         __be32 src_ip;
477         u_int8_t dst_hw[ETH_ALEN];
478         __be32 dst_ip;
479 } __packed;
480 
481 #ifdef DEBUG
482 static void arp_print(struct arp_payload *payload)
483 {
484 #define HBUFFERLEN 30
485         char hbuffer[HBUFFERLEN];
486         int j,k;
487 
488         for (k=0, j=0; k < HBUFFERLEN-3 && j < ETH_ALEN; j++) {
489                 hbuffer[k++] = hex_asc_hi(payload->src_hw[j]);
490                 hbuffer[k++] = hex_asc_lo(payload->src_hw[j]);
491                 hbuffer[k++]=':';
492         }
493         hbuffer[--k]='\0';
494 
495         pr_debug("src %pI4@%s, dst %pI4\n",
496                  &payload->src_ip, hbuffer, &payload->dst_ip);
497 }
498 #endif
499 
500 static unsigned int
501 arp_mangle(unsigned int hook,
502            struct sk_buff *skb,
503            const struct net_device *in,
504            const struct net_device *out,
505            int (*okfn)(struct sk_buff *))
506 {
507         struct arphdr *arp = arp_hdr(skb);
508         struct arp_payload *payload;
509         struct clusterip_config *c;
510 
511         /* we don't care about non-ethernet and non-ipv4 ARP */
512         if (arp->ar_hrd != htons(ARPHRD_ETHER) ||
513             arp->ar_pro != htons(ETH_P_IP) ||
514             arp->ar_pln != 4 || arp->ar_hln != ETH_ALEN)
515                 return NF_ACCEPT;
516 
517         /* we only want to mangle arp requests and replies */
518         if (arp->ar_op != htons(ARPOP_REPLY) &&
519             arp->ar_op != htons(ARPOP_REQUEST))
520                 return NF_ACCEPT;
521 
522         payload = (void *)(arp+1);
523 
524         /* if there is no clusterip configuration for the arp reply's
525          * source ip, we don't want to mangle it */
526         c = clusterip_config_find_get(payload->src_ip, 0);
527         if (!c)
528                 return NF_ACCEPT;
529 
530         /* normally the linux kernel always replies to arp queries of
531          * addresses on different interfacs.  However, in the CLUSTERIP case
532          * this wouldn't work, since we didn't subscribe the mcast group on
533          * other interfaces */
534         if (c->dev != out) {
535                 pr_debug("not mangling arp reply on different "
536                          "interface: cip'%s'-skb'%s'\n",
537                          c->dev->name, out->name);
538                 clusterip_config_put(c);
539                 return NF_ACCEPT;
540         }
541 
542         /* mangle reply hardware address */
543         memcpy(payload->src_hw, c->clustermac, arp->ar_hln);
544 
545 #ifdef DEBUG
546         pr_debug("mangled arp reply: ");
547         arp_print(payload);
548 #endif
549 
550         clusterip_config_put(c);
551 
552         return NF_ACCEPT;
553 }
554 
555 static struct nf_hook_ops cip_arp_ops __read_mostly = {
556         .hook = arp_mangle,
557         .pf = NFPROTO_ARP,
558         .hooknum = NF_ARP_OUT,
559         .priority = -1
560 };
561 
562 /***********************************************************************
563  * PROC DIR HANDLING
564  ***********************************************************************/
565 
566 #ifdef CONFIG_PROC_FS
567 
568 struct clusterip_seq_position {
569         unsigned int pos;       /* position */
570         unsigned int weight;    /* number of bits set == size */
571         unsigned int bit;       /* current bit */
572         unsigned long val;      /* current value */
573 };
574 
575 static void *clusterip_seq_start(struct seq_file *s, loff_t *pos)
576 {
577         struct clusterip_config *c = s->private;
578         unsigned int weight;
579         u_int32_t local_nodes;
580         struct clusterip_seq_position *idx;
581 
582         /* FIXME: possible race */
583         local_nodes = c->local_nodes;
584         weight = hweight32(local_nodes);
585         if (*pos >= weight)
586                 return NULL;
587 
588         idx = kmalloc(sizeof(struct clusterip_seq_position), GFP_KERNEL);
589         if (!idx)
590                 return ERR_PTR(-ENOMEM);
591 
592         idx->pos = *pos;
593         idx->weight = weight;
594         idx->bit = ffs(local_nodes);
595         idx->val = local_nodes;
596         clear_bit(idx->bit - 1, &idx->val);
597 
598         return idx;
599 }
600 
601 static void *clusterip_seq_next(struct seq_file *s, void *v, loff_t *pos)
602 {
603         struct clusterip_seq_position *idx = v;
604 
605         *pos = ++idx->pos;
606         if (*pos >= idx->weight) {
607                 kfree(v);
608                 return NULL;
609         }
610         idx->bit = ffs(idx->val);
611         clear_bit(idx->bit - 1, &idx->val);
612         return idx;
613 }
614 
615 static void clusterip_seq_stop(struct seq_file *s, void *v)
616 {
617         if (!IS_ERR(v))
618                 kfree(v);
619 }
620 
621 static int clusterip_seq_show(struct seq_file *s, void *v)
622 {
623         struct clusterip_seq_position *idx = v;
624 
625         if (idx->pos != 0)
626                 seq_putc(s, ',');
627 
628         seq_printf(s, "%u", idx->bit);
629 
630         if (idx->pos == idx->weight - 1)
631                 seq_putc(s, '\n');
632 
633         return 0;
634 }
635 
636 static const struct seq_operations clusterip_seq_ops = {
637         .start  = clusterip_seq_start,
638         .next   = clusterip_seq_next,
639         .stop   = clusterip_seq_stop,
640         .show   = clusterip_seq_show,
641 };
642 
643 static int clusterip_proc_open(struct inode *inode, struct file *file)
644 {
645         int ret = seq_open(file, &clusterip_seq_ops);
646 
647         if (!ret) {
648                 struct seq_file *sf = file->private_data;
649                 struct clusterip_config *c = PDE(inode)->data;
650 
651                 sf->private = c;
652 
653                 clusterip_config_get(c);
654         }
655 
656         return ret;
657 }
658 
659 static int clusterip_proc_release(struct inode *inode, struct file *file)
660 {
661         struct clusterip_config *c = PDE(inode)->data;
662         int ret;
663 
664         ret = seq_release(inode, file);
665 
666         if (!ret)
667                 clusterip_config_put(c);
668 
669         return ret;
670 }
671 
672 static ssize_t clusterip_proc_write(struct file *file, const char __user *input,
673                                 size_t size, loff_t *ofs)
674 {
675         struct clusterip_config *c = PDE(file->f_path.dentry->d_inode)->data;
676 #define PROC_WRITELEN   10
677         char buffer[PROC_WRITELEN+1];
678         unsigned long nodenum;
679 
680         if (size > PROC_WRITELEN)
681                 return -EIO;
682         if (copy_from_user(buffer, input, size))
683                 return -EFAULT;
684         buffer[size] = 0;
685 
686         if (*buffer == '+') {
687                 nodenum = simple_strtoul(buffer+1, NULL, 10);
688                 if (clusterip_add_node(c, nodenum))
689                         return -ENOMEM;
690         } else if (*buffer == '-') {
691                 nodenum = simple_strtoul(buffer+1, NULL,10);
692                 if (clusterip_del_node(c, nodenum))
693                         return -ENOENT;
694         } else
695                 return -EIO;
696 
697         return size;
698 }
699 
700 static const struct file_operations clusterip_proc_fops = {
701         .owner   = THIS_MODULE,
702         .open    = clusterip_proc_open,
703         .read    = seq_read,
704         .write   = clusterip_proc_write,
705         .llseek  = seq_lseek,
706         .release = clusterip_proc_release,
707 };
708 
709 #endif /* CONFIG_PROC_FS */
710 
711 static int __init clusterip_tg_init(void)
712 {
713         int ret;
714 
715         ret = xt_register_target(&clusterip_tg_reg);
716         if (ret < 0)
717                 return ret;
718 
719         ret = nf_register_hook(&cip_arp_ops);
720         if (ret < 0)
721                 goto cleanup_target;
722 
723 #ifdef CONFIG_PROC_FS
724         clusterip_procdir = proc_mkdir("ipt_CLUSTERIP", init_net.proc_net);
725         if (!clusterip_procdir) {
726                 pr_err("Unable to proc dir entry\n");
727                 ret = -ENOMEM;
728                 goto cleanup_hook;
729         }
730 #endif /* CONFIG_PROC_FS */
731 
732         pr_info("ClusterIP Version %s loaded successfully\n",
733                 CLUSTERIP_VERSION);
734         return 0;
735 
736 #ifdef CONFIG_PROC_FS
737 cleanup_hook:
738         nf_unregister_hook(&cip_arp_ops);
739 #endif /* CONFIG_PROC_FS */
740 cleanup_target:
741         xt_unregister_target(&clusterip_tg_reg);
742         return ret;
743 }
744 
745 static void __exit clusterip_tg_exit(void)
746 {
747         pr_info("ClusterIP Version %s unloading\n", CLUSTERIP_VERSION);
748 #ifdef CONFIG_PROC_FS
749         remove_proc_entry(clusterip_procdir->name, clusterip_procdir->parent);
750 #endif
751         nf_unregister_hook(&cip_arp_ops);
752         xt_unregister_target(&clusterip_tg_reg);
753 
754         /* Wait for completion of call_rcu_bh()'s (clusterip_config_rcu_free) */
755         rcu_barrier_bh();
756 }
757 
758 module_init(clusterip_tg_init);
759 module_exit(clusterip_tg_exit);
760 

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