Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland...
[linux-2.6] / net / ipv4 / netfilter / arp_tables.c
1 /*
2  * Packet matching code for ARP packets.
3  *
4  * Based heavily, if not almost entirely, upon ip_tables.c framework.
5  *
6  * Some ARP specific bits are:
7  *
8  * Copyright (C) 2002 David S. Miller (davem@redhat.com)
9  *
10  */
11
12 #include <linux/config.h>
13 #include <linux/kernel.h>
14 #include <linux/skbuff.h>
15 #include <linux/netdevice.h>
16 #include <linux/if_arp.h>
17 #include <linux/kmod.h>
18 #include <linux/vmalloc.h>
19 #include <linux/proc_fs.h>
20 #include <linux/module.h>
21 #include <linux/init.h>
22
23 #include <asm/uaccess.h>
24 #include <asm/semaphore.h>
25
26 #include <linux/netfilter_arp/arp_tables.h>
27
28 MODULE_LICENSE("GPL");
29 MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
30 MODULE_DESCRIPTION("arptables core");
31
32 /*#define DEBUG_ARP_TABLES*/
33 /*#define DEBUG_ARP_TABLES_USER*/
34
35 #ifdef DEBUG_ARP_TABLES
36 #define dprintf(format, args...)  printk(format , ## args)
37 #else
38 #define dprintf(format, args...)
39 #endif
40
41 #ifdef DEBUG_ARP_TABLES_USER
42 #define duprintf(format, args...) printk(format , ## args)
43 #else
44 #define duprintf(format, args...)
45 #endif
46
47 #ifdef CONFIG_NETFILTER_DEBUG
48 #define ARP_NF_ASSERT(x)                                        \
49 do {                                                            \
50         if (!(x))                                               \
51                 printk("ARP_NF_ASSERT: %s:%s:%u\n",             \
52                        __FUNCTION__, __FILE__, __LINE__);       \
53 } while(0)
54 #else
55 #define ARP_NF_ASSERT(x)
56 #endif
57 #define SMP_ALIGN(x) (((x) + SMP_CACHE_BYTES-1) & ~(SMP_CACHE_BYTES-1))
58
59 static DECLARE_MUTEX(arpt_mutex);
60
61 #define ASSERT_READ_LOCK(x) ARP_NF_ASSERT(down_trylock(&arpt_mutex) != 0)
62 #define ASSERT_WRITE_LOCK(x) ARP_NF_ASSERT(down_trylock(&arpt_mutex) != 0)
63 #include <linux/netfilter_ipv4/listhelp.h>
64
65 struct arpt_table_info {
66         unsigned int size;
67         unsigned int number;
68         unsigned int initial_entries;
69         unsigned int hook_entry[NF_ARP_NUMHOOKS];
70         unsigned int underflow[NF_ARP_NUMHOOKS];
71         void *entries[NR_CPUS];
72 };
73
74 static LIST_HEAD(arpt_target);
75 static LIST_HEAD(arpt_tables);
76 #define SET_COUNTER(c,b,p) do { (c).bcnt = (b); (c).pcnt = (p); } while(0)
77 #define ADD_COUNTER(c,b,p) do { (c).bcnt += (b); (c).pcnt += (p); } while(0)
78
79 static inline int arp_devaddr_compare(const struct arpt_devaddr_info *ap,
80                                       char *hdr_addr, int len)
81 {
82         int i, ret;
83
84         if (len > ARPT_DEV_ADDR_LEN_MAX)
85                 len = ARPT_DEV_ADDR_LEN_MAX;
86
87         ret = 0;
88         for (i = 0; i < len; i++)
89                 ret |= (hdr_addr[i] ^ ap->addr[i]) & ap->mask[i];
90
91         return (ret != 0);
92 }
93
94 /* Returns whether packet matches rule or not. */
95 static inline int arp_packet_match(const struct arphdr *arphdr,
96                                    struct net_device *dev,
97                                    const char *indev,
98                                    const char *outdev,
99                                    const struct arpt_arp *arpinfo)
100 {
101         char *arpptr = (char *)(arphdr + 1);
102         char *src_devaddr, *tgt_devaddr;
103         u32 src_ipaddr, tgt_ipaddr;
104         int i, ret;
105
106 #define FWINV(bool,invflg) ((bool) ^ !!(arpinfo->invflags & invflg))
107
108         if (FWINV((arphdr->ar_op & arpinfo->arpop_mask) != arpinfo->arpop,
109                   ARPT_INV_ARPOP)) {
110                 dprintf("ARP operation field mismatch.\n");
111                 dprintf("ar_op: %04x info->arpop: %04x info->arpop_mask: %04x\n",
112                         arphdr->ar_op, arpinfo->arpop, arpinfo->arpop_mask);
113                 return 0;
114         }
115
116         if (FWINV((arphdr->ar_hrd & arpinfo->arhrd_mask) != arpinfo->arhrd,
117                   ARPT_INV_ARPHRD)) {
118                 dprintf("ARP hardware address format mismatch.\n");
119                 dprintf("ar_hrd: %04x info->arhrd: %04x info->arhrd_mask: %04x\n",
120                         arphdr->ar_hrd, arpinfo->arhrd, arpinfo->arhrd_mask);
121                 return 0;
122         }
123
124         if (FWINV((arphdr->ar_pro & arpinfo->arpro_mask) != arpinfo->arpro,
125                   ARPT_INV_ARPPRO)) {
126                 dprintf("ARP protocol address format mismatch.\n");
127                 dprintf("ar_pro: %04x info->arpro: %04x info->arpro_mask: %04x\n",
128                         arphdr->ar_pro, arpinfo->arpro, arpinfo->arpro_mask);
129                 return 0;
130         }
131
132         if (FWINV((arphdr->ar_hln & arpinfo->arhln_mask) != arpinfo->arhln,
133                   ARPT_INV_ARPHLN)) {
134                 dprintf("ARP hardware address length mismatch.\n");
135                 dprintf("ar_hln: %02x info->arhln: %02x info->arhln_mask: %02x\n",
136                         arphdr->ar_hln, arpinfo->arhln, arpinfo->arhln_mask);
137                 return 0;
138         }
139
140         src_devaddr = arpptr;
141         arpptr += dev->addr_len;
142         memcpy(&src_ipaddr, arpptr, sizeof(u32));
143         arpptr += sizeof(u32);
144         tgt_devaddr = arpptr;
145         arpptr += dev->addr_len;
146         memcpy(&tgt_ipaddr, arpptr, sizeof(u32));
147
148         if (FWINV(arp_devaddr_compare(&arpinfo->src_devaddr, src_devaddr, dev->addr_len),
149                   ARPT_INV_SRCDEVADDR) ||
150             FWINV(arp_devaddr_compare(&arpinfo->tgt_devaddr, tgt_devaddr, dev->addr_len),
151                   ARPT_INV_TGTDEVADDR)) {
152                 dprintf("Source or target device address mismatch.\n");
153
154                 return 0;
155         }
156
157         if (FWINV((src_ipaddr & arpinfo->smsk.s_addr) != arpinfo->src.s_addr,
158                   ARPT_INV_SRCIP) ||
159             FWINV(((tgt_ipaddr & arpinfo->tmsk.s_addr) != arpinfo->tgt.s_addr),
160                   ARPT_INV_TGTIP)) {
161                 dprintf("Source or target IP address mismatch.\n");
162
163                 dprintf("SRC: %u.%u.%u.%u. Mask: %u.%u.%u.%u. Target: %u.%u.%u.%u.%s\n",
164                         NIPQUAD(src_ipaddr),
165                         NIPQUAD(arpinfo->smsk.s_addr),
166                         NIPQUAD(arpinfo->src.s_addr),
167                         arpinfo->invflags & ARPT_INV_SRCIP ? " (INV)" : "");
168                 dprintf("TGT: %u.%u.%u.%u Mask: %u.%u.%u.%u Target: %u.%u.%u.%u.%s\n",
169                         NIPQUAD(tgt_ipaddr),
170                         NIPQUAD(arpinfo->tmsk.s_addr),
171                         NIPQUAD(arpinfo->tgt.s_addr),
172                         arpinfo->invflags & ARPT_INV_TGTIP ? " (INV)" : "");
173                 return 0;
174         }
175
176         /* Look for ifname matches.  */
177         for (i = 0, ret = 0; i < IFNAMSIZ; i++) {
178                 ret |= (indev[i] ^ arpinfo->iniface[i])
179                         & arpinfo->iniface_mask[i];
180         }
181
182         if (FWINV(ret != 0, ARPT_INV_VIA_IN)) {
183                 dprintf("VIA in mismatch (%s vs %s).%s\n",
184                         indev, arpinfo->iniface,
185                         arpinfo->invflags&ARPT_INV_VIA_IN ?" (INV)":"");
186                 return 0;
187         }
188
189         for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned long); i++) {
190                 unsigned long odev;
191                 memcpy(&odev, outdev + i*sizeof(unsigned long),
192                        sizeof(unsigned long));
193                 ret |= (odev
194                         ^ ((const unsigned long *)arpinfo->outiface)[i])
195                         & ((const unsigned long *)arpinfo->outiface_mask)[i];
196         }
197
198         if (FWINV(ret != 0, ARPT_INV_VIA_OUT)) {
199                 dprintf("VIA out mismatch (%s vs %s).%s\n",
200                         outdev, arpinfo->outiface,
201                         arpinfo->invflags&ARPT_INV_VIA_OUT ?" (INV)":"");
202                 return 0;
203         }
204
205         return 1;
206 }
207
208 static inline int arp_checkentry(const struct arpt_arp *arp)
209 {
210         if (arp->flags & ~ARPT_F_MASK) {
211                 duprintf("Unknown flag bits set: %08X\n",
212                          arp->flags & ~ARPT_F_MASK);
213                 return 0;
214         }
215         if (arp->invflags & ~ARPT_INV_MASK) {
216                 duprintf("Unknown invflag bits set: %08X\n",
217                          arp->invflags & ~ARPT_INV_MASK);
218                 return 0;
219         }
220
221         return 1;
222 }
223
224 static unsigned int arpt_error(struct sk_buff **pskb,
225                                unsigned int hooknum,
226                                const struct net_device *in,
227                                const struct net_device *out,
228                                const void *targinfo,
229                                void *userinfo)
230 {
231         if (net_ratelimit())
232                 printk("arp_tables: error: '%s'\n", (char *)targinfo);
233
234         return NF_DROP;
235 }
236
237 static inline struct arpt_entry *get_entry(void *base, unsigned int offset)
238 {
239         return (struct arpt_entry *)(base + offset);
240 }
241
242 unsigned int arpt_do_table(struct sk_buff **pskb,
243                            unsigned int hook,
244                            const struct net_device *in,
245                            const struct net_device *out,
246                            struct arpt_table *table,
247                            void *userdata)
248 {
249         static const char nulldevname[IFNAMSIZ];
250         unsigned int verdict = NF_DROP;
251         struct arphdr *arp;
252         int hotdrop = 0;
253         struct arpt_entry *e, *back;
254         const char *indev, *outdev;
255         void *table_base;
256
257         /* ARP header, plus 2 device addresses, plus 2 IP addresses.  */
258         if (!pskb_may_pull((*pskb), (sizeof(struct arphdr) +
259                                      (2 * (*pskb)->dev->addr_len) +
260                                      (2 * sizeof(u32)))))
261                 return NF_DROP;
262
263         indev = in ? in->name : nulldevname;
264         outdev = out ? out->name : nulldevname;
265
266         read_lock_bh(&table->lock);
267         table_base = (void *)table->private->entries[smp_processor_id()];
268         e = get_entry(table_base, table->private->hook_entry[hook]);
269         back = get_entry(table_base, table->private->underflow[hook]);
270
271         arp = (*pskb)->nh.arph;
272         do {
273                 if (arp_packet_match(arp, (*pskb)->dev, indev, outdev, &e->arp)) {
274                         struct arpt_entry_target *t;
275                         int hdr_len;
276
277                         hdr_len = sizeof(*arp) + (2 * sizeof(struct in_addr)) +
278                                 (2 * (*pskb)->dev->addr_len);
279                         ADD_COUNTER(e->counters, hdr_len, 1);
280
281                         t = arpt_get_target(e);
282
283                         /* Standard target? */
284                         if (!t->u.kernel.target->target) {
285                                 int v;
286
287                                 v = ((struct arpt_standard_target *)t)->verdict;
288                                 if (v < 0) {
289                                         /* Pop from stack? */
290                                         if (v != ARPT_RETURN) {
291                                                 verdict = (unsigned)(-v) - 1;
292                                                 break;
293                                         }
294                                         e = back;
295                                         back = get_entry(table_base,
296                                                          back->comefrom);
297                                         continue;
298                                 }
299                                 if (table_base + v
300                                     != (void *)e + e->next_offset) {
301                                         /* Save old back ptr in next entry */
302                                         struct arpt_entry *next
303                                                 = (void *)e + e->next_offset;
304                                         next->comefrom =
305                                                 (void *)back - table_base;
306
307                                         /* set back pointer to next entry */
308                                         back = next;
309                                 }
310
311                                 e = get_entry(table_base, v);
312                         } else {
313                                 /* Targets which reenter must return
314                                  * abs. verdicts
315                                  */
316                                 verdict = t->u.kernel.target->target(pskb,
317                                                                      hook,
318                                                                      in, out,
319                                                                      t->data,
320                                                                      userdata);
321
322                                 /* Target might have changed stuff. */
323                                 arp = (*pskb)->nh.arph;
324
325                                 if (verdict == ARPT_CONTINUE)
326                                         e = (void *)e + e->next_offset;
327                                 else
328                                         /* Verdict */
329                                         break;
330                         }
331                 } else {
332                         e = (void *)e + e->next_offset;
333                 }
334         } while (!hotdrop);
335         read_unlock_bh(&table->lock);
336
337         if (hotdrop)
338                 return NF_DROP;
339         else
340                 return verdict;
341 }
342
343 /*
344  * These are weird, but module loading must not be done with mutex
345  * held (since they will register), and we have to have a single
346  * function to use try_then_request_module().
347  */
348
349 /* Find table by name, grabs mutex & ref.  Returns ERR_PTR() on error. */
350 static inline struct arpt_table *find_table_lock(const char *name)
351 {
352         struct arpt_table *t;
353
354         if (down_interruptible(&arpt_mutex) != 0)
355                 return ERR_PTR(-EINTR);
356
357         list_for_each_entry(t, &arpt_tables, list)
358                 if (strcmp(t->name, name) == 0 && try_module_get(t->me))
359                         return t;
360         up(&arpt_mutex);
361         return NULL;
362 }
363
364
365 /* Find target, grabs ref.  Returns ERR_PTR() on error. */
366 static inline struct arpt_target *find_target(const char *name, u8 revision)
367 {
368         struct arpt_target *t;
369         int err = 0;
370
371         if (down_interruptible(&arpt_mutex) != 0)
372                 return ERR_PTR(-EINTR);
373
374         list_for_each_entry(t, &arpt_target, list) {
375                 if (strcmp(t->name, name) == 0) {
376                         if (t->revision == revision) {
377                                 if (try_module_get(t->me)) {
378                                         up(&arpt_mutex);
379                                         return t;
380                                 }
381                         } else
382                                 err = -EPROTOTYPE; /* Found something. */
383                 }
384         }
385         up(&arpt_mutex);
386         return ERR_PTR(err);
387 }
388
389 struct arpt_target *arpt_find_target(const char *name, u8 revision)
390 {
391         struct arpt_target *target;
392
393         target = try_then_request_module(find_target(name, revision),
394                                          "arpt_%s", name);
395         if (IS_ERR(target) || !target)
396                 return NULL;
397         return target;
398 }
399
400 static int target_revfn(const char *name, u8 revision, int *bestp)
401 {
402         struct arpt_target *t;
403         int have_rev = 0;
404
405         list_for_each_entry(t, &arpt_target, list) {
406                 if (strcmp(t->name, name) == 0) {
407                         if (t->revision > *bestp)
408                                 *bestp = t->revision;
409                         if (t->revision == revision)
410                                 have_rev =1;
411                 }
412         }
413         return have_rev;
414 }
415
416 /* Returns true or false (if no such extension at all) */
417 static inline int find_revision(const char *name, u8 revision,
418                                 int (*revfn)(const char *, u8, int *),
419                                 int *err)
420 {
421         int have_rev, best = -1;
422
423         if (down_interruptible(&arpt_mutex) != 0) {
424                 *err = -EINTR;
425                 return 1;
426         }
427         have_rev = revfn(name, revision, &best);
428         up(&arpt_mutex);
429
430         /* Nothing at all?  Return 0 to try loading module. */
431         if (best == -1) {
432                 *err = -ENOENT;
433                 return 0;
434         }
435
436         *err = best;
437         if (!have_rev)
438                 *err = -EPROTONOSUPPORT;
439         return 1;
440 }
441
442
443 /* All zeroes == unconditional rule. */
444 static inline int unconditional(const struct arpt_arp *arp)
445 {
446         unsigned int i;
447
448         for (i = 0; i < sizeof(*arp)/sizeof(__u32); i++)
449                 if (((__u32 *)arp)[i])
450                         return 0;
451
452         return 1;
453 }
454
455 /* Figures out from what hook each rule can be called: returns 0 if
456  * there are loops.  Puts hook bitmask in comefrom.
457  */
458 static int mark_source_chains(struct arpt_table_info *newinfo,
459                               unsigned int valid_hooks, void *entry0)
460 {
461         unsigned int hook;
462
463         /* No recursion; use packet counter to save back ptrs (reset
464          * to 0 as we leave), and comefrom to save source hook bitmask.
465          */
466         for (hook = 0; hook < NF_ARP_NUMHOOKS; hook++) {
467                 unsigned int pos = newinfo->hook_entry[hook];
468                 struct arpt_entry *e
469                         = (struct arpt_entry *)(entry0 + pos);
470
471                 if (!(valid_hooks & (1 << hook)))
472                         continue;
473
474                 /* Set initial back pointer. */
475                 e->counters.pcnt = pos;
476
477                 for (;;) {
478                         struct arpt_standard_target *t
479                                 = (void *)arpt_get_target(e);
480
481                         if (e->comefrom & (1 << NF_ARP_NUMHOOKS)) {
482                                 printk("arptables: loop hook %u pos %u %08X.\n",
483                                        hook, pos, e->comefrom);
484                                 return 0;
485                         }
486                         e->comefrom
487                                 |= ((1 << hook) | (1 << NF_ARP_NUMHOOKS));
488
489                         /* Unconditional return/END. */
490                         if (e->target_offset == sizeof(struct arpt_entry)
491                             && (strcmp(t->target.u.user.name,
492                                        ARPT_STANDARD_TARGET) == 0)
493                             && t->verdict < 0
494                             && unconditional(&e->arp)) {
495                                 unsigned int oldpos, size;
496
497                                 /* Return: backtrack through the last
498                                  * big jump.
499                                  */
500                                 do {
501                                         e->comefrom ^= (1<<NF_ARP_NUMHOOKS);
502                                         oldpos = pos;
503                                         pos = e->counters.pcnt;
504                                         e->counters.pcnt = 0;
505
506                                         /* We're at the start. */
507                                         if (pos == oldpos)
508                                                 goto next;
509
510                                         e = (struct arpt_entry *)
511                                                 (entry0 + pos);
512                                 } while (oldpos == pos + e->next_offset);
513
514                                 /* Move along one */
515                                 size = e->next_offset;
516                                 e = (struct arpt_entry *)
517                                         (entry0 + pos + size);
518                                 e->counters.pcnt = pos;
519                                 pos += size;
520                         } else {
521                                 int newpos = t->verdict;
522
523                                 if (strcmp(t->target.u.user.name,
524                                            ARPT_STANDARD_TARGET) == 0
525                                     && newpos >= 0) {
526                                         /* This a jump; chase it. */
527                                         duprintf("Jump rule %u -> %u\n",
528                                                  pos, newpos);
529                                 } else {
530                                         /* ... this is a fallthru */
531                                         newpos = pos + e->next_offset;
532                                 }
533                                 e = (struct arpt_entry *)
534                                         (entry0 + newpos);
535                                 e->counters.pcnt = pos;
536                                 pos = newpos;
537                         }
538                 }
539                 next:
540                 duprintf("Finished chain %u\n", hook);
541         }
542         return 1;
543 }
544
545 static inline int standard_check(const struct arpt_entry_target *t,
546                                  unsigned int max_offset)
547 {
548         struct arpt_standard_target *targ = (void *)t;
549
550         /* Check standard info. */
551         if (t->u.target_size
552             != ARPT_ALIGN(sizeof(struct arpt_standard_target))) {
553                 duprintf("arpt_standard_check: target size %u != %Zu\n",
554                          t->u.target_size,
555                          ARPT_ALIGN(sizeof(struct arpt_standard_target)));
556                 return 0;
557         }
558
559         if (targ->verdict >= 0
560             && targ->verdict > max_offset - sizeof(struct arpt_entry)) {
561                 duprintf("arpt_standard_check: bad verdict (%i)\n",
562                          targ->verdict);
563                 return 0;
564         }
565
566         if (targ->verdict < -NF_MAX_VERDICT - 1) {
567                 duprintf("arpt_standard_check: bad negative verdict (%i)\n",
568                          targ->verdict);
569                 return 0;
570         }
571         return 1;
572 }
573
574 static struct arpt_target arpt_standard_target;
575
576 static inline int check_entry(struct arpt_entry *e, const char *name, unsigned int size,
577                               unsigned int *i)
578 {
579         struct arpt_entry_target *t;
580         struct arpt_target *target;
581         int ret;
582
583         if (!arp_checkentry(&e->arp)) {
584                 duprintf("arp_tables: arp check failed %p %s.\n", e, name);
585                 return -EINVAL;
586         }
587
588         t = arpt_get_target(e);
589         target = try_then_request_module(find_target(t->u.user.name,
590                                                      t->u.user.revision),
591                                          "arpt_%s", t->u.user.name);
592         if (IS_ERR(target) || !target) {
593                 duprintf("check_entry: `%s' not found\n", t->u.user.name);
594                 ret = target ? PTR_ERR(target) : -ENOENT;
595                 goto out;
596         }
597         t->u.kernel.target = target;
598
599         if (t->u.kernel.target == &arpt_standard_target) {
600                 if (!standard_check(t, size)) {
601                         ret = -EINVAL;
602                         goto out;
603                 }
604         } else if (t->u.kernel.target->checkentry
605                    && !t->u.kernel.target->checkentry(name, e, t->data,
606                                                       t->u.target_size
607                                                       - sizeof(*t),
608                                                       e->comefrom)) {
609                 module_put(t->u.kernel.target->me);
610                 duprintf("arp_tables: check failed for `%s'.\n",
611                          t->u.kernel.target->name);
612                 ret = -EINVAL;
613                 goto out;
614         }
615
616         (*i)++;
617         return 0;
618
619 out:
620         return ret;
621 }
622
623 static inline int check_entry_size_and_hooks(struct arpt_entry *e,
624                                              struct arpt_table_info *newinfo,
625                                              unsigned char *base,
626                                              unsigned char *limit,
627                                              const unsigned int *hook_entries,
628                                              const unsigned int *underflows,
629                                              unsigned int *i)
630 {
631         unsigned int h;
632
633         if ((unsigned long)e % __alignof__(struct arpt_entry) != 0
634             || (unsigned char *)e + sizeof(struct arpt_entry) >= limit) {
635                 duprintf("Bad offset %p\n", e);
636                 return -EINVAL;
637         }
638
639         if (e->next_offset
640             < sizeof(struct arpt_entry) + sizeof(struct arpt_entry_target)) {
641                 duprintf("checking: element %p size %u\n",
642                          e, e->next_offset);
643                 return -EINVAL;
644         }
645
646         /* Check hooks & underflows */
647         for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
648                 if ((unsigned char *)e - base == hook_entries[h])
649                         newinfo->hook_entry[h] = hook_entries[h];
650                 if ((unsigned char *)e - base == underflows[h])
651                         newinfo->underflow[h] = underflows[h];
652         }
653
654         /* FIXME: underflows must be unconditional, standard verdicts
655            < 0 (not ARPT_RETURN). --RR */
656
657         /* Clear counters and comefrom */
658         e->counters = ((struct arpt_counters) { 0, 0 });
659         e->comefrom = 0;
660
661         (*i)++;
662         return 0;
663 }
664
665 static inline int cleanup_entry(struct arpt_entry *e, unsigned int *i)
666 {
667         struct arpt_entry_target *t;
668
669         if (i && (*i)-- == 0)
670                 return 1;
671
672         t = arpt_get_target(e);
673         if (t->u.kernel.target->destroy)
674                 t->u.kernel.target->destroy(t->data,
675                                             t->u.target_size - sizeof(*t));
676         module_put(t->u.kernel.target->me);
677         return 0;
678 }
679
680 /* Checks and translates the user-supplied table segment (held in
681  * newinfo).
682  */
683 static int translate_table(const char *name,
684                            unsigned int valid_hooks,
685                            struct arpt_table_info *newinfo,
686                            void *entry0,
687                            unsigned int size,
688                            unsigned int number,
689                            const unsigned int *hook_entries,
690                            const unsigned int *underflows)
691 {
692         unsigned int i;
693         int ret;
694
695         newinfo->size = size;
696         newinfo->number = number;
697
698         /* Init all hooks to impossible value. */
699         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
700                 newinfo->hook_entry[i] = 0xFFFFFFFF;
701                 newinfo->underflow[i] = 0xFFFFFFFF;
702         }
703
704         duprintf("translate_table: size %u\n", newinfo->size);
705         i = 0;
706
707         /* Walk through entries, checking offsets. */
708         ret = ARPT_ENTRY_ITERATE(entry0, newinfo->size,
709                                  check_entry_size_and_hooks,
710                                  newinfo,
711                                  entry0,
712                                  entry0 + size,
713                                  hook_entries, underflows, &i);
714         duprintf("translate_table: ARPT_ENTRY_ITERATE gives %d\n", ret);
715         if (ret != 0)
716                 return ret;
717
718         if (i != number) {
719                 duprintf("translate_table: %u not %u entries\n",
720                          i, number);
721                 return -EINVAL;
722         }
723
724         /* Check hooks all assigned */
725         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
726                 /* Only hooks which are valid */
727                 if (!(valid_hooks & (1 << i)))
728                         continue;
729                 if (newinfo->hook_entry[i] == 0xFFFFFFFF) {
730                         duprintf("Invalid hook entry %u %u\n",
731                                  i, hook_entries[i]);
732                         return -EINVAL;
733                 }
734                 if (newinfo->underflow[i] == 0xFFFFFFFF) {
735                         duprintf("Invalid underflow %u %u\n",
736                                  i, underflows[i]);
737                         return -EINVAL;
738                 }
739         }
740
741         if (!mark_source_chains(newinfo, valid_hooks, entry0)) {
742                 duprintf("Looping hook\n");
743                 return -ELOOP;
744         }
745
746         /* Finally, each sanity check must pass */
747         i = 0;
748         ret = ARPT_ENTRY_ITERATE(entry0, newinfo->size,
749                                  check_entry, name, size, &i);
750
751         if (ret != 0) {
752                 ARPT_ENTRY_ITERATE(entry0, newinfo->size,
753                                    cleanup_entry, &i);
754                 return ret;
755         }
756
757         /* And one copy for every other CPU */
758         for_each_cpu(i) {
759                 if (newinfo->entries[i] && newinfo->entries[i] != entry0)
760                         memcpy(newinfo->entries[i], entry0, newinfo->size);
761         }
762
763         return ret;
764 }
765
766 static struct arpt_table_info *replace_table(struct arpt_table *table,
767                                              unsigned int num_counters,
768                                              struct arpt_table_info *newinfo,
769                                              int *error)
770 {
771         struct arpt_table_info *oldinfo;
772
773         /* Do the substitution. */
774         write_lock_bh(&table->lock);
775         /* Check inside lock: is the old number correct? */
776         if (num_counters != table->private->number) {
777                 duprintf("num_counters != table->private->number (%u/%u)\n",
778                          num_counters, table->private->number);
779                 write_unlock_bh(&table->lock);
780                 *error = -EAGAIN;
781                 return NULL;
782         }
783         oldinfo = table->private;
784         table->private = newinfo;
785         newinfo->initial_entries = oldinfo->initial_entries;
786         write_unlock_bh(&table->lock);
787
788         return oldinfo;
789 }
790
791 /* Gets counters. */
792 static inline int add_entry_to_counter(const struct arpt_entry *e,
793                                        struct arpt_counters total[],
794                                        unsigned int *i)
795 {
796         ADD_COUNTER(total[*i], e->counters.bcnt, e->counters.pcnt);
797
798         (*i)++;
799         return 0;
800 }
801
802 static inline int set_entry_to_counter(const struct arpt_entry *e,
803                                        struct arpt_counters total[],
804                                        unsigned int *i)
805 {
806         SET_COUNTER(total[*i], e->counters.bcnt, e->counters.pcnt);
807
808         (*i)++;
809         return 0;
810 }
811
812 static void get_counters(const struct arpt_table_info *t,
813                          struct arpt_counters counters[])
814 {
815         unsigned int cpu;
816         unsigned int i;
817         unsigned int curcpu;
818
819         /* Instead of clearing (by a previous call to memset())
820          * the counters and using adds, we set the counters
821          * with data used by 'current' CPU
822          * We dont care about preemption here.
823          */
824         curcpu = raw_smp_processor_id();
825
826         i = 0;
827         ARPT_ENTRY_ITERATE(t->entries[curcpu],
828                            t->size,
829                            set_entry_to_counter,
830                            counters,
831                            &i);
832
833         for_each_cpu(cpu) {
834                 if (cpu == curcpu)
835                         continue;
836                 i = 0;
837                 ARPT_ENTRY_ITERATE(t->entries[cpu],
838                                    t->size,
839                                    add_entry_to_counter,
840                                    counters,
841                                    &i);
842         }
843 }
844
845 static int copy_entries_to_user(unsigned int total_size,
846                                 struct arpt_table *table,
847                                 void __user *userptr)
848 {
849         unsigned int off, num, countersize;
850         struct arpt_entry *e;
851         struct arpt_counters *counters;
852         int ret = 0;
853         void *loc_cpu_entry;
854
855         /* We need atomic snapshot of counters: rest doesn't change
856          * (other than comefrom, which userspace doesn't care
857          * about).
858          */
859         countersize = sizeof(struct arpt_counters) * table->private->number;
860         counters = vmalloc(countersize);
861
862         if (counters == NULL)
863                 return -ENOMEM;
864
865         /* First, sum counters... */
866         write_lock_bh(&table->lock);
867         get_counters(table->private, counters);
868         write_unlock_bh(&table->lock);
869
870         loc_cpu_entry = table->private->entries[raw_smp_processor_id()];
871         /* ... then copy entire thing ... */
872         if (copy_to_user(userptr, loc_cpu_entry, total_size) != 0) {
873                 ret = -EFAULT;
874                 goto free_counters;
875         }
876
877         /* FIXME: use iterator macros --RR */
878         /* ... then go back and fix counters and names */
879         for (off = 0, num = 0; off < total_size; off += e->next_offset, num++){
880                 struct arpt_entry_target *t;
881
882                 e = (struct arpt_entry *)(loc_cpu_entry + off);
883                 if (copy_to_user(userptr + off
884                                  + offsetof(struct arpt_entry, counters),
885                                  &counters[num],
886                                  sizeof(counters[num])) != 0) {
887                         ret = -EFAULT;
888                         goto free_counters;
889                 }
890
891                 t = arpt_get_target(e);
892                 if (copy_to_user(userptr + off + e->target_offset
893                                  + offsetof(struct arpt_entry_target,
894                                             u.user.name),
895                                  t->u.kernel.target->name,
896                                  strlen(t->u.kernel.target->name)+1) != 0) {
897                         ret = -EFAULT;
898                         goto free_counters;
899                 }
900         }
901
902  free_counters:
903         vfree(counters);
904         return ret;
905 }
906
907 static int get_entries(const struct arpt_get_entries *entries,
908                        struct arpt_get_entries __user *uptr)
909 {
910         int ret;
911         struct arpt_table *t;
912
913         t = find_table_lock(entries->name);
914         if (t || !IS_ERR(t)) {
915                 duprintf("t->private->number = %u\n",
916                          t->private->number);
917                 if (entries->size == t->private->size)
918                         ret = copy_entries_to_user(t->private->size,
919                                                    t, uptr->entrytable);
920                 else {
921                         duprintf("get_entries: I've got %u not %u!\n",
922                                  t->private->size,
923                                  entries->size);
924                         ret = -EINVAL;
925                 }
926                 module_put(t->me);
927                 up(&arpt_mutex);
928         } else
929                 ret = t ? PTR_ERR(t) : -ENOENT;
930
931         return ret;
932 }
933
934 static void free_table_info(struct arpt_table_info *info)
935 {
936         int cpu;
937         for_each_cpu(cpu) {
938                 if (info->size <= PAGE_SIZE)
939                         kfree(info->entries[cpu]);
940                 else
941                         vfree(info->entries[cpu]);
942         }
943         kfree(info);
944 }
945
946 static struct arpt_table_info *alloc_table_info(unsigned int size)
947 {
948         struct arpt_table_info *newinfo;
949         int cpu;
950         
951         newinfo = kzalloc(sizeof(struct arpt_table_info), GFP_KERNEL);
952         if (!newinfo)
953                 return NULL;
954
955         newinfo->size = size;
956
957         for_each_cpu(cpu) {
958                 if (size <= PAGE_SIZE)
959                         newinfo->entries[cpu] = kmalloc_node(size,
960                                                         GFP_KERNEL,
961                                                         cpu_to_node(cpu));
962                 else
963                         newinfo->entries[cpu] = vmalloc_node(size,
964                                                              cpu_to_node(cpu));
965
966                 if (newinfo->entries[cpu] == NULL) {
967                         free_table_info(newinfo);
968                         return NULL;
969                 }
970         }
971
972         return newinfo;
973 }
974
975 static int do_replace(void __user *user, unsigned int len)
976 {
977         int ret;
978         struct arpt_replace tmp;
979         struct arpt_table *t;
980         struct arpt_table_info *newinfo, *oldinfo;
981         struct arpt_counters *counters;
982         void *loc_cpu_entry, *loc_cpu_old_entry;
983
984         if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
985                 return -EFAULT;
986
987         /* Hack: Causes ipchains to give correct error msg --RR */
988         if (len != sizeof(tmp) + tmp.size)
989                 return -ENOPROTOOPT;
990
991         /* Pedantry: prevent them from hitting BUG() in vmalloc.c --RR */
992         if ((SMP_ALIGN(tmp.size) >> PAGE_SHIFT) + 2 > num_physpages)
993                 return -ENOMEM;
994
995         newinfo = alloc_table_info(tmp.size);
996         if (!newinfo)
997                 return -ENOMEM;
998
999         /* choose the copy that is on our node/cpu */
1000         loc_cpu_entry = newinfo->entries[raw_smp_processor_id()];
1001         if (copy_from_user(loc_cpu_entry, user + sizeof(tmp),
1002                            tmp.size) != 0) {
1003                 ret = -EFAULT;
1004                 goto free_newinfo;
1005         }
1006
1007         counters = vmalloc(tmp.num_counters * sizeof(struct arpt_counters));
1008         if (!counters) {
1009                 ret = -ENOMEM;
1010                 goto free_newinfo;
1011         }
1012
1013         ret = translate_table(tmp.name, tmp.valid_hooks,
1014                               newinfo, loc_cpu_entry, tmp.size, tmp.num_entries,
1015                               tmp.hook_entry, tmp.underflow);
1016         if (ret != 0)
1017                 goto free_newinfo_counters;
1018
1019         duprintf("arp_tables: Translated table\n");
1020
1021         t = try_then_request_module(find_table_lock(tmp.name),
1022                                     "arptable_%s", tmp.name);
1023         if (!t || IS_ERR(t)) {
1024                 ret = t ? PTR_ERR(t) : -ENOENT;
1025                 goto free_newinfo_counters_untrans;
1026         }
1027
1028         /* You lied! */
1029         if (tmp.valid_hooks != t->valid_hooks) {
1030                 duprintf("Valid hook crap: %08X vs %08X\n",
1031                          tmp.valid_hooks, t->valid_hooks);
1032                 ret = -EINVAL;
1033                 goto put_module;
1034         }
1035
1036         oldinfo = replace_table(t, tmp.num_counters, newinfo, &ret);
1037         if (!oldinfo)
1038                 goto put_module;
1039
1040         /* Update module usage count based on number of rules */
1041         duprintf("do_replace: oldnum=%u, initnum=%u, newnum=%u\n",
1042                 oldinfo->number, oldinfo->initial_entries, newinfo->number);
1043         if ((oldinfo->number > oldinfo->initial_entries) || 
1044             (newinfo->number <= oldinfo->initial_entries)) 
1045                 module_put(t->me);
1046         if ((oldinfo->number > oldinfo->initial_entries) &&
1047             (newinfo->number <= oldinfo->initial_entries))
1048                 module_put(t->me);
1049
1050         /* Get the old counters. */
1051         get_counters(oldinfo, counters);
1052         /* Decrease module usage counts and free resource */
1053         loc_cpu_old_entry = oldinfo->entries[raw_smp_processor_id()];
1054         ARPT_ENTRY_ITERATE(loc_cpu_old_entry, oldinfo->size, cleanup_entry,NULL);
1055
1056         free_table_info(oldinfo);
1057         if (copy_to_user(tmp.counters, counters,
1058                          sizeof(struct arpt_counters) * tmp.num_counters) != 0)
1059                 ret = -EFAULT;
1060         vfree(counters);
1061         up(&arpt_mutex);
1062         return ret;
1063
1064  put_module:
1065         module_put(t->me);
1066         up(&arpt_mutex);
1067  free_newinfo_counters_untrans:
1068         ARPT_ENTRY_ITERATE(loc_cpu_entry, newinfo->size, cleanup_entry, NULL);
1069  free_newinfo_counters:
1070         vfree(counters);
1071  free_newinfo:
1072         free_table_info(newinfo);
1073         return ret;
1074 }
1075
1076 /* We're lazy, and add to the first CPU; overflow works its fey magic
1077  * and everything is OK.
1078  */
1079 static inline int add_counter_to_entry(struct arpt_entry *e,
1080                                        const struct arpt_counters addme[],
1081                                        unsigned int *i)
1082 {
1083
1084         ADD_COUNTER(e->counters, addme[*i].bcnt, addme[*i].pcnt);
1085
1086         (*i)++;
1087         return 0;
1088 }
1089
1090 static int do_add_counters(void __user *user, unsigned int len)
1091 {
1092         unsigned int i;
1093         struct arpt_counters_info tmp, *paddc;
1094         struct arpt_table *t;
1095         int ret = 0;
1096         void *loc_cpu_entry;
1097
1098         if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
1099                 return -EFAULT;
1100
1101         if (len != sizeof(tmp) + tmp.num_counters*sizeof(struct arpt_counters))
1102                 return -EINVAL;
1103
1104         paddc = vmalloc(len);
1105         if (!paddc)
1106                 return -ENOMEM;
1107
1108         if (copy_from_user(paddc, user, len) != 0) {
1109                 ret = -EFAULT;
1110                 goto free;
1111         }
1112
1113         t = find_table_lock(tmp.name);
1114         if (!t || IS_ERR(t)) {
1115                 ret = t ? PTR_ERR(t) : -ENOENT;
1116                 goto free;
1117         }
1118
1119         write_lock_bh(&t->lock);
1120         if (t->private->number != paddc->num_counters) {
1121                 ret = -EINVAL;
1122                 goto unlock_up_free;
1123         }
1124
1125         i = 0;
1126         /* Choose the copy that is on our node */
1127         loc_cpu_entry = t->private->entries[smp_processor_id()];
1128         ARPT_ENTRY_ITERATE(loc_cpu_entry,
1129                            t->private->size,
1130                            add_counter_to_entry,
1131                            paddc->counters,
1132                            &i);
1133  unlock_up_free:
1134         write_unlock_bh(&t->lock);
1135         up(&arpt_mutex);
1136         module_put(t->me);
1137  free:
1138         vfree(paddc);
1139
1140         return ret;
1141 }
1142
1143 static int do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
1144 {
1145         int ret;
1146
1147         if (!capable(CAP_NET_ADMIN))
1148                 return -EPERM;
1149
1150         switch (cmd) {
1151         case ARPT_SO_SET_REPLACE:
1152                 ret = do_replace(user, len);
1153                 break;
1154
1155         case ARPT_SO_SET_ADD_COUNTERS:
1156                 ret = do_add_counters(user, len);
1157                 break;
1158
1159         default:
1160                 duprintf("do_arpt_set_ctl:  unknown request %i\n", cmd);
1161                 ret = -EINVAL;
1162         }
1163
1164         return ret;
1165 }
1166
1167 static int do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
1168 {
1169         int ret;
1170
1171         if (!capable(CAP_NET_ADMIN))
1172                 return -EPERM;
1173
1174         switch (cmd) {
1175         case ARPT_SO_GET_INFO: {
1176                 char name[ARPT_TABLE_MAXNAMELEN];
1177                 struct arpt_table *t;
1178
1179                 if (*len != sizeof(struct arpt_getinfo)) {
1180                         duprintf("length %u != %Zu\n", *len,
1181                                  sizeof(struct arpt_getinfo));
1182                         ret = -EINVAL;
1183                         break;
1184                 }
1185
1186                 if (copy_from_user(name, user, sizeof(name)) != 0) {
1187                         ret = -EFAULT;
1188                         break;
1189                 }
1190                 name[ARPT_TABLE_MAXNAMELEN-1] = '\0';
1191
1192                 t = try_then_request_module(find_table_lock(name),
1193                                             "arptable_%s", name);
1194                 if (t && !IS_ERR(t)) {
1195                         struct arpt_getinfo info;
1196
1197                         info.valid_hooks = t->valid_hooks;
1198                         memcpy(info.hook_entry, t->private->hook_entry,
1199                                sizeof(info.hook_entry));
1200                         memcpy(info.underflow, t->private->underflow,
1201                                sizeof(info.underflow));
1202                         info.num_entries = t->private->number;
1203                         info.size = t->private->size;
1204                         strcpy(info.name, name);
1205
1206                         if (copy_to_user(user, &info, *len) != 0)
1207                                 ret = -EFAULT;
1208                         else
1209                                 ret = 0;
1210                         up(&arpt_mutex);
1211                         module_put(t->me);
1212                 } else
1213                         ret = t ? PTR_ERR(t) : -ENOENT;
1214         }
1215         break;
1216
1217         case ARPT_SO_GET_ENTRIES: {
1218                 struct arpt_get_entries get;
1219
1220                 if (*len < sizeof(get)) {
1221                         duprintf("get_entries: %u < %Zu\n", *len, sizeof(get));
1222                         ret = -EINVAL;
1223                 } else if (copy_from_user(&get, user, sizeof(get)) != 0) {
1224                         ret = -EFAULT;
1225                 } else if (*len != sizeof(struct arpt_get_entries) + get.size) {
1226                         duprintf("get_entries: %u != %Zu\n", *len,
1227                                  sizeof(struct arpt_get_entries) + get.size);
1228                         ret = -EINVAL;
1229                 } else
1230                         ret = get_entries(&get, user);
1231                 break;
1232         }
1233
1234         case ARPT_SO_GET_REVISION_TARGET: {
1235                 struct arpt_get_revision rev;
1236
1237                 if (*len != sizeof(rev)) {
1238                         ret = -EINVAL;
1239                         break;
1240                 }
1241                 if (copy_from_user(&rev, user, sizeof(rev)) != 0) {
1242                         ret = -EFAULT;
1243                         break;
1244                 }
1245
1246                 try_then_request_module(find_revision(rev.name, rev.revision,
1247                                                       target_revfn, &ret),
1248                                         "arpt_%s", rev.name);
1249                 break;
1250         }
1251
1252         default:
1253                 duprintf("do_arpt_get_ctl: unknown request %i\n", cmd);
1254                 ret = -EINVAL;
1255         }
1256
1257         return ret;
1258 }
1259
1260 /* Registration hooks for targets. */
1261 int arpt_register_target(struct arpt_target *target)
1262 {
1263         int ret;
1264
1265         ret = down_interruptible(&arpt_mutex);
1266         if (ret != 0)
1267                 return ret;
1268
1269         list_add(&target->list, &arpt_target);
1270         up(&arpt_mutex);
1271
1272         return ret;
1273 }
1274
1275 void arpt_unregister_target(struct arpt_target *target)
1276 {
1277         down(&arpt_mutex);
1278         LIST_DELETE(&arpt_target, target);
1279         up(&arpt_mutex);
1280 }
1281
1282 int arpt_register_table(struct arpt_table *table,
1283                         const struct arpt_replace *repl)
1284 {
1285         int ret;
1286         struct arpt_table_info *newinfo;
1287         static struct arpt_table_info bootstrap
1288                 = { 0, 0, 0, { 0 }, { 0 }, { } };
1289         void *loc_cpu_entry;
1290
1291         newinfo = alloc_table_info(repl->size);
1292         if (!newinfo) {
1293                 ret = -ENOMEM;
1294                 return ret;
1295         }
1296
1297         /* choose the copy on our node/cpu */
1298         loc_cpu_entry = newinfo->entries[raw_smp_processor_id()];
1299         memcpy(loc_cpu_entry, repl->entries, repl->size);
1300
1301         ret = translate_table(table->name, table->valid_hooks,
1302                               newinfo, loc_cpu_entry, repl->size,
1303                               repl->num_entries,
1304                               repl->hook_entry,
1305                               repl->underflow);
1306         duprintf("arpt_register_table: translate table gives %d\n", ret);
1307         if (ret != 0) {
1308                 free_table_info(newinfo);
1309                 return ret;
1310         }
1311
1312         ret = down_interruptible(&arpt_mutex);
1313         if (ret != 0) {
1314                 free_table_info(newinfo);
1315                 return ret;
1316         }
1317
1318         /* Don't autoload: we'd eat our tail... */
1319         if (list_named_find(&arpt_tables, table->name)) {
1320                 ret = -EEXIST;
1321                 goto free_unlock;
1322         }
1323
1324         /* Simplifies replace_table code. */
1325         table->private = &bootstrap;
1326         if (!replace_table(table, 0, newinfo, &ret))
1327                 goto free_unlock;
1328
1329         duprintf("table->private->number = %u\n",
1330                  table->private->number);
1331         
1332         /* save number of initial entries */
1333         table->private->initial_entries = table->private->number;
1334
1335         rwlock_init(&table->lock);
1336         list_prepend(&arpt_tables, table);
1337
1338  unlock:
1339         up(&arpt_mutex);
1340         return ret;
1341
1342  free_unlock:
1343         free_table_info(newinfo);
1344         goto unlock;
1345 }
1346
1347 void arpt_unregister_table(struct arpt_table *table)
1348 {
1349         void *loc_cpu_entry;
1350
1351         down(&arpt_mutex);
1352         LIST_DELETE(&arpt_tables, table);
1353         up(&arpt_mutex);
1354
1355         /* Decrease module usage counts and free resources */
1356         loc_cpu_entry = table->private->entries[raw_smp_processor_id()];
1357         ARPT_ENTRY_ITERATE(loc_cpu_entry, table->private->size,
1358                            cleanup_entry, NULL);
1359         free_table_info(table->private);
1360 }
1361
1362 /* The built-in targets: standard (NULL) and error. */
1363 static struct arpt_target arpt_standard_target = {
1364         .name           = ARPT_STANDARD_TARGET,
1365 };
1366
1367 static struct arpt_target arpt_error_target = {
1368         .name           = ARPT_ERROR_TARGET,
1369         .target         = arpt_error,
1370 };
1371
1372 static struct nf_sockopt_ops arpt_sockopts = {
1373         .pf             = PF_INET,
1374         .set_optmin     = ARPT_BASE_CTL,
1375         .set_optmax     = ARPT_SO_SET_MAX+1,
1376         .set            = do_arpt_set_ctl,
1377         .get_optmin     = ARPT_BASE_CTL,
1378         .get_optmax     = ARPT_SO_GET_MAX+1,
1379         .get            = do_arpt_get_ctl,
1380 };
1381
1382 #ifdef CONFIG_PROC_FS
1383 static inline int print_name(const struct arpt_table *t,
1384                              off_t start_offset, char *buffer, int length,
1385                              off_t *pos, unsigned int *count)
1386 {
1387         if ((*count)++ >= start_offset) {
1388                 unsigned int namelen;
1389
1390                 namelen = sprintf(buffer + *pos, "%s\n", t->name);
1391                 if (*pos + namelen > length) {
1392                         /* Stop iterating */
1393                         return 1;
1394                 }
1395                 *pos += namelen;
1396         }
1397         return 0;
1398 }
1399
1400 static int arpt_get_tables(char *buffer, char **start, off_t offset, int length)
1401 {
1402         off_t pos = 0;
1403         unsigned int count = 0;
1404
1405         if (down_interruptible(&arpt_mutex) != 0)
1406                 return 0;
1407
1408         LIST_FIND(&arpt_tables, print_name, struct arpt_table *,
1409                   offset, buffer, length, &pos, &count);
1410
1411         up(&arpt_mutex);
1412
1413         /* `start' hack - see fs/proc/generic.c line ~105 */
1414         *start=(char *)((unsigned long)count-offset);
1415         return pos;
1416 }
1417 #endif /*CONFIG_PROC_FS*/
1418
1419 static int __init init(void)
1420 {
1421         int ret;
1422
1423         /* Noone else will be downing sem now, so we won't sleep */
1424         down(&arpt_mutex);
1425         list_append(&arpt_target, &arpt_standard_target);
1426         list_append(&arpt_target, &arpt_error_target);
1427         up(&arpt_mutex);
1428
1429         /* Register setsockopt */
1430         ret = nf_register_sockopt(&arpt_sockopts);
1431         if (ret < 0) {
1432                 duprintf("Unable to register sockopts.\n");
1433                 return ret;
1434         }
1435
1436 #ifdef CONFIG_PROC_FS
1437         {
1438                 struct proc_dir_entry *proc;
1439
1440                 proc = proc_net_create("arp_tables_names", 0, arpt_get_tables);
1441                 if (!proc) {
1442                         nf_unregister_sockopt(&arpt_sockopts);
1443                         return -ENOMEM;
1444                 }
1445                 proc->owner = THIS_MODULE;
1446         }
1447 #endif
1448
1449         printk("arp_tables: (C) 2002 David S. Miller\n");
1450         return 0;
1451 }
1452
1453 static void __exit fini(void)
1454 {
1455         nf_unregister_sockopt(&arpt_sockopts);
1456 #ifdef CONFIG_PROC_FS
1457         proc_net_remove("arp_tables_names");
1458 #endif
1459 }
1460
1461 EXPORT_SYMBOL(arpt_register_table);
1462 EXPORT_SYMBOL(arpt_unregister_table);
1463 EXPORT_SYMBOL(arpt_do_table);
1464 EXPORT_SYMBOL(arpt_register_target);
1465 EXPORT_SYMBOL(arpt_unregister_target);
1466
1467 module_init(init);
1468 module_exit(fini);