fa1634256680d88f524727da2b48fdfe92360732
[linux-3.10.git] / 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         char entries[0] __attribute__((aligned(SMP_CACHE_BYTES)));
72 };
73
74 static LIST_HEAD(arpt_target);
75 static LIST_HEAD(arpt_tables);
76 #define ADD_COUNTER(c,b,p) do { (c).bcnt += (b); (c).pcnt += (p); } while(0)
77
78 #ifdef CONFIG_SMP
79 #define TABLE_OFFSET(t,p) (SMP_ALIGN((t)->size)*(p))
80 #else
81 #define TABLE_OFFSET(t,p) 0
82 #endif
83
84 static inline int arp_devaddr_compare(const struct arpt_devaddr_info *ap,
85                                       char *hdr_addr, int len)
86 {
87         int i, ret;
88
89         if (len > ARPT_DEV_ADDR_LEN_MAX)
90                 len = ARPT_DEV_ADDR_LEN_MAX;
91
92         ret = 0;
93         for (i = 0; i < len; i++)
94                 ret |= (hdr_addr[i] ^ ap->addr[i]) & ap->mask[i];
95
96         return (ret != 0);
97 }
98
99 /* Returns whether packet matches rule or not. */
100 static inline int arp_packet_match(const struct arphdr *arphdr,
101                                    struct net_device *dev,
102                                    const char *indev,
103                                    const char *outdev,
104                                    const struct arpt_arp *arpinfo)
105 {
106         char *arpptr = (char *)(arphdr + 1);
107         char *src_devaddr, *tgt_devaddr;
108         u32 src_ipaddr, tgt_ipaddr;
109         int i, ret;
110
111 #define FWINV(bool,invflg) ((bool) ^ !!(arpinfo->invflags & invflg))
112
113         if (FWINV((arphdr->ar_op & arpinfo->arpop_mask) != arpinfo->arpop,
114                   ARPT_INV_ARPOP)) {
115                 dprintf("ARP operation field mismatch.\n");
116                 dprintf("ar_op: %04x info->arpop: %04x info->arpop_mask: %04x\n",
117                         arphdr->ar_op, arpinfo->arpop, arpinfo->arpop_mask);
118                 return 0;
119         }
120
121         if (FWINV((arphdr->ar_hrd & arpinfo->arhrd_mask) != arpinfo->arhrd,
122                   ARPT_INV_ARPHRD)) {
123                 dprintf("ARP hardware address format mismatch.\n");
124                 dprintf("ar_hrd: %04x info->arhrd: %04x info->arhrd_mask: %04x\n",
125                         arphdr->ar_hrd, arpinfo->arhrd, arpinfo->arhrd_mask);
126                 return 0;
127         }
128
129         if (FWINV((arphdr->ar_pro & arpinfo->arpro_mask) != arpinfo->arpro,
130                   ARPT_INV_ARPPRO)) {
131                 dprintf("ARP protocol address format mismatch.\n");
132                 dprintf("ar_pro: %04x info->arpro: %04x info->arpro_mask: %04x\n",
133                         arphdr->ar_pro, arpinfo->arpro, arpinfo->arpro_mask);
134                 return 0;
135         }
136
137         if (FWINV((arphdr->ar_hln & arpinfo->arhln_mask) != arpinfo->arhln,
138                   ARPT_INV_ARPHLN)) {
139                 dprintf("ARP hardware address length mismatch.\n");
140                 dprintf("ar_hln: %02x info->arhln: %02x info->arhln_mask: %02x\n",
141                         arphdr->ar_hln, arpinfo->arhln, arpinfo->arhln_mask);
142                 return 0;
143         }
144
145         src_devaddr = arpptr;
146         arpptr += dev->addr_len;
147         memcpy(&src_ipaddr, arpptr, sizeof(u32));
148         arpptr += sizeof(u32);
149         tgt_devaddr = arpptr;
150         arpptr += dev->addr_len;
151         memcpy(&tgt_ipaddr, arpptr, sizeof(u32));
152
153         if (FWINV(arp_devaddr_compare(&arpinfo->src_devaddr, src_devaddr, dev->addr_len),
154                   ARPT_INV_SRCDEVADDR) ||
155             FWINV(arp_devaddr_compare(&arpinfo->tgt_devaddr, tgt_devaddr, dev->addr_len),
156                   ARPT_INV_TGTDEVADDR)) {
157                 dprintf("Source or target device address mismatch.\n");
158
159                 return 0;
160         }
161
162         if (FWINV((src_ipaddr & arpinfo->smsk.s_addr) != arpinfo->src.s_addr,
163                   ARPT_INV_SRCIP) ||
164             FWINV(((tgt_ipaddr & arpinfo->tmsk.s_addr) != arpinfo->tgt.s_addr),
165                   ARPT_INV_TGTIP)) {
166                 dprintf("Source or target IP address mismatch.\n");
167
168                 dprintf("SRC: %u.%u.%u.%u. Mask: %u.%u.%u.%u. Target: %u.%u.%u.%u.%s\n",
169                         NIPQUAD(src_ipaddr),
170                         NIPQUAD(arpinfo->smsk.s_addr),
171                         NIPQUAD(arpinfo->src.s_addr),
172                         arpinfo->invflags & ARPT_INV_SRCIP ? " (INV)" : "");
173                 dprintf("TGT: %u.%u.%u.%u Mask: %u.%u.%u.%u Target: %u.%u.%u.%u.%s\n",
174                         NIPQUAD(tgt_ipaddr),
175                         NIPQUAD(arpinfo->tmsk.s_addr),
176                         NIPQUAD(arpinfo->tgt.s_addr),
177                         arpinfo->invflags & ARPT_INV_TGTIP ? " (INV)" : "");
178                 return 0;
179         }
180
181         /* Look for ifname matches.  */
182         for (i = 0, ret = 0; i < IFNAMSIZ; i++) {
183                 ret |= (indev[i] ^ arpinfo->iniface[i])
184                         & arpinfo->iniface_mask[i];
185         }
186
187         if (FWINV(ret != 0, ARPT_INV_VIA_IN)) {
188                 dprintf("VIA in mismatch (%s vs %s).%s\n",
189                         indev, arpinfo->iniface,
190                         arpinfo->invflags&ARPT_INV_VIA_IN ?" (INV)":"");
191                 return 0;
192         }
193
194         for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned long); i++) {
195                 unsigned long odev;
196                 memcpy(&odev, outdev + i*sizeof(unsigned long),
197                        sizeof(unsigned long));
198                 ret |= (odev
199                         ^ ((const unsigned long *)arpinfo->outiface)[i])
200                         & ((const unsigned long *)arpinfo->outiface_mask)[i];
201         }
202
203         if (FWINV(ret != 0, ARPT_INV_VIA_OUT)) {
204                 dprintf("VIA out mismatch (%s vs %s).%s\n",
205                         outdev, arpinfo->outiface,
206                         arpinfo->invflags&ARPT_INV_VIA_OUT ?" (INV)":"");
207                 return 0;
208         }
209
210         return 1;
211 }
212
213 static inline int arp_checkentry(const struct arpt_arp *arp)
214 {
215         if (arp->flags & ~ARPT_F_MASK) {
216                 duprintf("Unknown flag bits set: %08X\n",
217                          arp->flags & ~ARPT_F_MASK);
218                 return 0;
219         }
220         if (arp->invflags & ~ARPT_INV_MASK) {
221                 duprintf("Unknown invflag bits set: %08X\n",
222                          arp->invflags & ~ARPT_INV_MASK);
223                 return 0;
224         }
225
226         return 1;
227 }
228
229 static unsigned int arpt_error(struct sk_buff **pskb,
230                                unsigned int hooknum,
231                                const struct net_device *in,
232                                const struct net_device *out,
233                                const void *targinfo,
234                                void *userinfo)
235 {
236         if (net_ratelimit())
237                 printk("arp_tables: error: '%s'\n", (char *)targinfo);
238
239         return NF_DROP;
240 }
241
242 static inline struct arpt_entry *get_entry(void *base, unsigned int offset)
243 {
244         return (struct arpt_entry *)(base + offset);
245 }
246
247 unsigned int arpt_do_table(struct sk_buff **pskb,
248                            unsigned int hook,
249                            const struct net_device *in,
250                            const struct net_device *out,
251                            struct arpt_table *table,
252                            void *userdata)
253 {
254         static const char nulldevname[IFNAMSIZ];
255         unsigned int verdict = NF_DROP;
256         struct arphdr *arp;
257         int hotdrop = 0;
258         struct arpt_entry *e, *back;
259         const char *indev, *outdev;
260         void *table_base;
261
262         /* ARP header, plus 2 device addresses, plus 2 IP addresses.  */
263         if (!pskb_may_pull((*pskb), (sizeof(struct arphdr) +
264                                      (2 * (*pskb)->dev->addr_len) +
265                                      (2 * sizeof(u32)))))
266                 return NF_DROP;
267
268         indev = in ? in->name : nulldevname;
269         outdev = out ? out->name : nulldevname;
270
271         read_lock_bh(&table->lock);
272         table_base = (void *)table->private->entries
273                 + TABLE_OFFSET(table->private,
274                                smp_processor_id());
275         e = get_entry(table_base, table->private->hook_entry[hook]);
276         back = get_entry(table_base, table->private->underflow[hook]);
277
278         arp = (*pskb)->nh.arph;
279         do {
280                 if (arp_packet_match(arp, (*pskb)->dev, indev, outdev, &e->arp)) {
281                         struct arpt_entry_target *t;
282                         int hdr_len;
283
284                         hdr_len = sizeof(*arp) + (2 * sizeof(struct in_addr)) +
285                                 (2 * (*pskb)->dev->addr_len);
286                         ADD_COUNTER(e->counters, hdr_len, 1);
287
288                         t = arpt_get_target(e);
289
290                         /* Standard target? */
291                         if (!t->u.kernel.target->target) {
292                                 int v;
293
294                                 v = ((struct arpt_standard_target *)t)->verdict;
295                                 if (v < 0) {
296                                         /* Pop from stack? */
297                                         if (v != ARPT_RETURN) {
298                                                 verdict = (unsigned)(-v) - 1;
299                                                 break;
300                                         }
301                                         e = back;
302                                         back = get_entry(table_base,
303                                                          back->comefrom);
304                                         continue;
305                                 }
306                                 if (table_base + v
307                                     != (void *)e + e->next_offset) {
308                                         /* Save old back ptr in next entry */
309                                         struct arpt_entry *next
310                                                 = (void *)e + e->next_offset;
311                                         next->comefrom =
312                                                 (void *)back - table_base;
313
314                                         /* set back pointer to next entry */
315                                         back = next;
316                                 }
317
318                                 e = get_entry(table_base, v);
319                         } else {
320                                 /* Targets which reenter must return
321                                  * abs. verdicts
322                                  */
323                                 verdict = t->u.kernel.target->target(pskb,
324                                                                      hook,
325                                                                      in, out,
326                                                                      t->data,
327                                                                      userdata);
328
329                                 /* Target might have changed stuff. */
330                                 arp = (*pskb)->nh.arph;
331
332                                 if (verdict == ARPT_CONTINUE)
333                                         e = (void *)e + e->next_offset;
334                                 else
335                                         /* Verdict */
336                                         break;
337                         }
338                 } else {
339                         e = (void *)e + e->next_offset;
340                 }
341         } while (!hotdrop);
342         read_unlock_bh(&table->lock);
343
344         if (hotdrop)
345                 return NF_DROP;
346         else
347                 return verdict;
348 }
349
350 static inline void *find_inlist_lock_noload(struct list_head *head,
351                                             const char *name,
352                                             int *error,
353                                             struct semaphore *mutex)
354 {
355         void *ret;
356
357         *error = down_interruptible(mutex);
358         if (*error != 0)
359                 return NULL;
360
361         ret = list_named_find(head, name);
362         if (!ret) {
363                 *error = -ENOENT;
364                 up(mutex);
365         }
366         return ret;
367 }
368
369 #ifndef CONFIG_KMOD
370 #define find_inlist_lock(h,n,p,e,m) find_inlist_lock_noload((h),(n),(e),(m))
371 #else
372 static void *
373 find_inlist_lock(struct list_head *head,
374                  const char *name,
375                  const char *prefix,
376                  int *error,
377                  struct semaphore *mutex)
378 {
379         void *ret;
380
381         ret = find_inlist_lock_noload(head, name, error, mutex);
382         if (!ret) {
383                 duprintf("find_inlist: loading `%s%s'.\n", prefix, name);
384                 request_module("%s%s", prefix, name);
385                 ret = find_inlist_lock_noload(head, name, error, mutex);
386         }
387
388         return ret;
389 }
390 #endif
391
392 static inline struct arpt_table *arpt_find_table_lock(const char *name, int *error, struct semaphore *mutex)
393 {
394         return find_inlist_lock(&arpt_tables, name, "arptable_", error, mutex);
395 }
396
397 static struct arpt_target *arpt_find_target_lock(const char *name, int *error, struct semaphore *mutex)
398 {
399         return find_inlist_lock(&arpt_target, name, "arpt_", error, mutex);
400 }
401
402 /* All zeroes == unconditional rule. */
403 static inline int unconditional(const struct arpt_arp *arp)
404 {
405         unsigned int i;
406
407         for (i = 0; i < sizeof(*arp)/sizeof(__u32); i++)
408                 if (((__u32 *)arp)[i])
409                         return 0;
410
411         return 1;
412 }
413
414 /* Figures out from what hook each rule can be called: returns 0 if
415  * there are loops.  Puts hook bitmask in comefrom.
416  */
417 static int mark_source_chains(struct arpt_table_info *newinfo, unsigned int valid_hooks)
418 {
419         unsigned int hook;
420
421         /* No recursion; use packet counter to save back ptrs (reset
422          * to 0 as we leave), and comefrom to save source hook bitmask.
423          */
424         for (hook = 0; hook < NF_ARP_NUMHOOKS; hook++) {
425                 unsigned int pos = newinfo->hook_entry[hook];
426                 struct arpt_entry *e
427                         = (struct arpt_entry *)(newinfo->entries + pos);
428
429                 if (!(valid_hooks & (1 << hook)))
430                         continue;
431
432                 /* Set initial back pointer. */
433                 e->counters.pcnt = pos;
434
435                 for (;;) {
436                         struct arpt_standard_target *t
437                                 = (void *)arpt_get_target(e);
438
439                         if (e->comefrom & (1 << NF_ARP_NUMHOOKS)) {
440                                 printk("arptables: loop hook %u pos %u %08X.\n",
441                                        hook, pos, e->comefrom);
442                                 return 0;
443                         }
444                         e->comefrom
445                                 |= ((1 << hook) | (1 << NF_ARP_NUMHOOKS));
446
447                         /* Unconditional return/END. */
448                         if (e->target_offset == sizeof(struct arpt_entry)
449                             && (strcmp(t->target.u.user.name,
450                                        ARPT_STANDARD_TARGET) == 0)
451                             && t->verdict < 0
452                             && unconditional(&e->arp)) {
453                                 unsigned int oldpos, size;
454
455                                 /* Return: backtrack through the last
456                                  * big jump.
457                                  */
458                                 do {
459                                         e->comefrom ^= (1<<NF_ARP_NUMHOOKS);
460                                         oldpos = pos;
461                                         pos = e->counters.pcnt;
462                                         e->counters.pcnt = 0;
463
464                                         /* We're at the start. */
465                                         if (pos == oldpos)
466                                                 goto next;
467
468                                         e = (struct arpt_entry *)
469                                                 (newinfo->entries + pos);
470                                 } while (oldpos == pos + e->next_offset);
471
472                                 /* Move along one */
473                                 size = e->next_offset;
474                                 e = (struct arpt_entry *)
475                                         (newinfo->entries + pos + size);
476                                 e->counters.pcnt = pos;
477                                 pos += size;
478                         } else {
479                                 int newpos = t->verdict;
480
481                                 if (strcmp(t->target.u.user.name,
482                                            ARPT_STANDARD_TARGET) == 0
483                                     && newpos >= 0) {
484                                         /* This a jump; chase it. */
485                                         duprintf("Jump rule %u -> %u\n",
486                                                  pos, newpos);
487                                 } else {
488                                         /* ... this is a fallthru */
489                                         newpos = pos + e->next_offset;
490                                 }
491                                 e = (struct arpt_entry *)
492                                         (newinfo->entries + newpos);
493                                 e->counters.pcnt = pos;
494                                 pos = newpos;
495                         }
496                 }
497                 next:
498                 duprintf("Finished chain %u\n", hook);
499         }
500         return 1;
501 }
502
503 static inline int standard_check(const struct arpt_entry_target *t,
504                                  unsigned int max_offset)
505 {
506         struct arpt_standard_target *targ = (void *)t;
507
508         /* Check standard info. */
509         if (t->u.target_size
510             != ARPT_ALIGN(sizeof(struct arpt_standard_target))) {
511                 duprintf("arpt_standard_check: target size %u != %Zu\n",
512                          t->u.target_size,
513                          ARPT_ALIGN(sizeof(struct arpt_standard_target)));
514                 return 0;
515         }
516
517         if (targ->verdict >= 0
518             && targ->verdict > max_offset - sizeof(struct arpt_entry)) {
519                 duprintf("arpt_standard_check: bad verdict (%i)\n",
520                          targ->verdict);
521                 return 0;
522         }
523
524         if (targ->verdict < -NF_MAX_VERDICT - 1) {
525                 duprintf("arpt_standard_check: bad negative verdict (%i)\n",
526                          targ->verdict);
527                 return 0;
528         }
529         return 1;
530 }
531
532 static struct arpt_target arpt_standard_target;
533
534 static inline int check_entry(struct arpt_entry *e, const char *name, unsigned int size,
535                               unsigned int *i)
536 {
537         struct arpt_entry_target *t;
538         struct arpt_target *target;
539         int ret;
540
541         if (!arp_checkentry(&e->arp)) {
542                 duprintf("arp_tables: arp check failed %p %s.\n", e, name);
543                 return -EINVAL;
544         }
545
546         t = arpt_get_target(e);
547         target = arpt_find_target_lock(t->u.user.name, &ret, &arpt_mutex);
548         if (!target) {
549                 duprintf("check_entry: `%s' not found\n", t->u.user.name);
550                 goto out;
551         }
552         if (!try_module_get((target->me))) {
553                 ret = -ENOENT;
554                 goto out_unlock;
555         }
556         t->u.kernel.target = target;
557         up(&arpt_mutex);
558
559         if (t->u.kernel.target == &arpt_standard_target) {
560                 if (!standard_check(t, size)) {
561                         ret = -EINVAL;
562                         goto out;
563                 }
564         } else if (t->u.kernel.target->checkentry
565                    && !t->u.kernel.target->checkentry(name, e, t->data,
566                                                       t->u.target_size
567                                                       - sizeof(*t),
568                                                       e->comefrom)) {
569                 module_put(t->u.kernel.target->me);
570                 duprintf("arp_tables: check failed for `%s'.\n",
571                          t->u.kernel.target->name);
572                 ret = -EINVAL;
573                 goto out;
574         }
575
576         (*i)++;
577         return 0;
578
579 out_unlock:
580         up(&arpt_mutex);
581 out:
582         return ret;
583 }
584
585 static inline int check_entry_size_and_hooks(struct arpt_entry *e,
586                                              struct arpt_table_info *newinfo,
587                                              unsigned char *base,
588                                              unsigned char *limit,
589                                              const unsigned int *hook_entries,
590                                              const unsigned int *underflows,
591                                              unsigned int *i)
592 {
593         unsigned int h;
594
595         if ((unsigned long)e % __alignof__(struct arpt_entry) != 0
596             || (unsigned char *)e + sizeof(struct arpt_entry) >= limit) {
597                 duprintf("Bad offset %p\n", e);
598                 return -EINVAL;
599         }
600
601         if (e->next_offset
602             < sizeof(struct arpt_entry) + sizeof(struct arpt_entry_target)) {
603                 duprintf("checking: element %p size %u\n",
604                          e, e->next_offset);
605                 return -EINVAL;
606         }
607
608         /* Check hooks & underflows */
609         for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
610                 if ((unsigned char *)e - base == hook_entries[h])
611                         newinfo->hook_entry[h] = hook_entries[h];
612                 if ((unsigned char *)e - base == underflows[h])
613                         newinfo->underflow[h] = underflows[h];
614         }
615
616         /* FIXME: underflows must be unconditional, standard verdicts
617            < 0 (not ARPT_RETURN). --RR */
618
619         /* Clear counters and comefrom */
620         e->counters = ((struct arpt_counters) { 0, 0 });
621         e->comefrom = 0;
622
623         (*i)++;
624         return 0;
625 }
626
627 static inline int cleanup_entry(struct arpt_entry *e, unsigned int *i)
628 {
629         struct arpt_entry_target *t;
630
631         if (i && (*i)-- == 0)
632                 return 1;
633
634         t = arpt_get_target(e);
635         if (t->u.kernel.target->destroy)
636                 t->u.kernel.target->destroy(t->data,
637                                             t->u.target_size - sizeof(*t));
638         module_put(t->u.kernel.target->me);
639         return 0;
640 }
641
642 /* Checks and translates the user-supplied table segment (held in
643  * newinfo).
644  */
645 static int translate_table(const char *name,
646                            unsigned int valid_hooks,
647                            struct arpt_table_info *newinfo,
648                            unsigned int size,
649                            unsigned int number,
650                            const unsigned int *hook_entries,
651                            const unsigned int *underflows)
652 {
653         unsigned int i;
654         int ret;
655
656         newinfo->size = size;
657         newinfo->number = number;
658
659         /* Init all hooks to impossible value. */
660         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
661                 newinfo->hook_entry[i] = 0xFFFFFFFF;
662                 newinfo->underflow[i] = 0xFFFFFFFF;
663         }
664
665         duprintf("translate_table: size %u\n", newinfo->size);
666         i = 0;
667
668         /* Walk through entries, checking offsets. */
669         ret = ARPT_ENTRY_ITERATE(newinfo->entries, newinfo->size,
670                                  check_entry_size_and_hooks,
671                                  newinfo,
672                                  newinfo->entries,
673                                  newinfo->entries + size,
674                                  hook_entries, underflows, &i);
675         duprintf("translate_table: ARPT_ENTRY_ITERATE gives %d\n", ret);
676         if (ret != 0)
677                 return ret;
678
679         if (i != number) {
680                 duprintf("translate_table: %u not %u entries\n",
681                          i, number);
682                 return -EINVAL;
683         }
684
685         /* Check hooks all assigned */
686         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
687                 /* Only hooks which are valid */
688                 if (!(valid_hooks & (1 << i)))
689                         continue;
690                 if (newinfo->hook_entry[i] == 0xFFFFFFFF) {
691                         duprintf("Invalid hook entry %u %u\n",
692                                  i, hook_entries[i]);
693                         return -EINVAL;
694                 }
695                 if (newinfo->underflow[i] == 0xFFFFFFFF) {
696                         duprintf("Invalid underflow %u %u\n",
697                                  i, underflows[i]);
698                         return -EINVAL;
699                 }
700         }
701
702         if (!mark_source_chains(newinfo, valid_hooks)) {
703                 duprintf("Looping hook\n");
704                 return -ELOOP;
705         }
706
707         /* Finally, each sanity check must pass */
708         i = 0;
709         ret = ARPT_ENTRY_ITERATE(newinfo->entries, newinfo->size,
710                                  check_entry, name, size, &i);
711
712         if (ret != 0) {
713                 ARPT_ENTRY_ITERATE(newinfo->entries, newinfo->size,
714                                    cleanup_entry, &i);
715                 return ret;
716         }
717
718         /* And one copy for every other CPU */
719         for (i = 1; i < num_possible_cpus(); i++) {
720                 memcpy(newinfo->entries + SMP_ALIGN(newinfo->size)*i,
721                        newinfo->entries,
722                        SMP_ALIGN(newinfo->size));
723         }
724
725         return ret;
726 }
727
728 static struct arpt_table_info *replace_table(struct arpt_table *table,
729                                              unsigned int num_counters,
730                                              struct arpt_table_info *newinfo,
731                                              int *error)
732 {
733         struct arpt_table_info *oldinfo;
734
735         /* Do the substitution. */
736         write_lock_bh(&table->lock);
737         /* Check inside lock: is the old number correct? */
738         if (num_counters != table->private->number) {
739                 duprintf("num_counters != table->private->number (%u/%u)\n",
740                          num_counters, table->private->number);
741                 write_unlock_bh(&table->lock);
742                 *error = -EAGAIN;
743                 return NULL;
744         }
745         oldinfo = table->private;
746         table->private = newinfo;
747         newinfo->initial_entries = oldinfo->initial_entries;
748         write_unlock_bh(&table->lock);
749
750         return oldinfo;
751 }
752
753 /* Gets counters. */
754 static inline int add_entry_to_counter(const struct arpt_entry *e,
755                                        struct arpt_counters total[],
756                                        unsigned int *i)
757 {
758         ADD_COUNTER(total[*i], e->counters.bcnt, e->counters.pcnt);
759
760         (*i)++;
761         return 0;
762 }
763
764 static void get_counters(const struct arpt_table_info *t,
765                          struct arpt_counters counters[])
766 {
767         unsigned int cpu;
768         unsigned int i;
769
770         for (cpu = 0; cpu < num_possible_cpus(); cpu++) {
771                 i = 0;
772                 ARPT_ENTRY_ITERATE(t->entries + TABLE_OFFSET(t, cpu),
773                                    t->size,
774                                    add_entry_to_counter,
775                                    counters,
776                                    &i);
777         }
778 }
779
780 static int copy_entries_to_user(unsigned int total_size,
781                                 struct arpt_table *table,
782                                 void __user *userptr)
783 {
784         unsigned int off, num, countersize;
785         struct arpt_entry *e;
786         struct arpt_counters *counters;
787         int ret = 0;
788
789         /* We need atomic snapshot of counters: rest doesn't change
790          * (other than comefrom, which userspace doesn't care
791          * about).
792          */
793         countersize = sizeof(struct arpt_counters) * table->private->number;
794         counters = vmalloc(countersize);
795
796         if (counters == NULL)
797                 return -ENOMEM;
798
799         /* First, sum counters... */
800         memset(counters, 0, countersize);
801         write_lock_bh(&table->lock);
802         get_counters(table->private, counters);
803         write_unlock_bh(&table->lock);
804
805         /* ... then copy entire thing from CPU 0... */
806         if (copy_to_user(userptr, table->private->entries, total_size) != 0) {
807                 ret = -EFAULT;
808                 goto free_counters;
809         }
810
811         /* FIXME: use iterator macros --RR */
812         /* ... then go back and fix counters and names */
813         for (off = 0, num = 0; off < total_size; off += e->next_offset, num++){
814                 struct arpt_entry_target *t;
815
816                 e = (struct arpt_entry *)(table->private->entries + off);
817                 if (copy_to_user(userptr + off
818                                  + offsetof(struct arpt_entry, counters),
819                                  &counters[num],
820                                  sizeof(counters[num])) != 0) {
821                         ret = -EFAULT;
822                         goto free_counters;
823                 }
824
825                 t = arpt_get_target(e);
826                 if (copy_to_user(userptr + off + e->target_offset
827                                  + offsetof(struct arpt_entry_target,
828                                             u.user.name),
829                                  t->u.kernel.target->name,
830                                  strlen(t->u.kernel.target->name)+1) != 0) {
831                         ret = -EFAULT;
832                         goto free_counters;
833                 }
834         }
835
836  free_counters:
837         vfree(counters);
838         return ret;
839 }
840
841 static int get_entries(const struct arpt_get_entries *entries,
842                        struct arpt_get_entries __user *uptr)
843 {
844         int ret;
845         struct arpt_table *t;
846
847         t = arpt_find_table_lock(entries->name, &ret, &arpt_mutex);
848         if (t) {
849                 duprintf("t->private->number = %u\n",
850                          t->private->number);
851                 if (entries->size == t->private->size)
852                         ret = copy_entries_to_user(t->private->size,
853                                                    t, uptr->entrytable);
854                 else {
855                         duprintf("get_entries: I've got %u not %u!\n",
856                                  t->private->size,
857                                  entries->size);
858                         ret = -EINVAL;
859                 }
860                 up(&arpt_mutex);
861         } else
862                 duprintf("get_entries: Can't find %s!\n",
863                          entries->name);
864
865         return ret;
866 }
867
868 static int do_replace(void __user *user, unsigned int len)
869 {
870         int ret;
871         struct arpt_replace tmp;
872         struct arpt_table *t;
873         struct arpt_table_info *newinfo, *oldinfo;
874         struct arpt_counters *counters;
875
876         if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
877                 return -EFAULT;
878
879         /* Hack: Causes ipchains to give correct error msg --RR */
880         if (len != sizeof(tmp) + tmp.size)
881                 return -ENOPROTOOPT;
882
883         /* Pedantry: prevent them from hitting BUG() in vmalloc.c --RR */
884         if ((SMP_ALIGN(tmp.size) >> PAGE_SHIFT) + 2 > num_physpages)
885                 return -ENOMEM;
886
887         newinfo = vmalloc(sizeof(struct arpt_table_info)
888                           + SMP_ALIGN(tmp.size) * num_possible_cpus());
889         if (!newinfo)
890                 return -ENOMEM;
891
892         if (copy_from_user(newinfo->entries, user + sizeof(tmp),
893                            tmp.size) != 0) {
894                 ret = -EFAULT;
895                 goto free_newinfo;
896         }
897
898         counters = vmalloc(tmp.num_counters * sizeof(struct arpt_counters));
899         if (!counters) {
900                 ret = -ENOMEM;
901                 goto free_newinfo;
902         }
903         memset(counters, 0, tmp.num_counters * sizeof(struct arpt_counters));
904
905         ret = translate_table(tmp.name, tmp.valid_hooks,
906                               newinfo, tmp.size, tmp.num_entries,
907                               tmp.hook_entry, tmp.underflow);
908         if (ret != 0)
909                 goto free_newinfo_counters;
910
911         duprintf("arp_tables: Translated table\n");
912
913         t = arpt_find_table_lock(tmp.name, &ret, &arpt_mutex);
914         if (!t)
915                 goto free_newinfo_counters_untrans;
916
917         /* You lied! */
918         if (tmp.valid_hooks != t->valid_hooks) {
919                 duprintf("Valid hook crap: %08X vs %08X\n",
920                          tmp.valid_hooks, t->valid_hooks);
921                 ret = -EINVAL;
922                 goto free_newinfo_counters_untrans_unlock;
923         }
924
925         /* Get a reference in advance, we're not allowed fail later */
926         if (!try_module_get(t->me)) {
927                 ret = -EBUSY;
928                 goto free_newinfo_counters_untrans_unlock;
929         }
930
931         oldinfo = replace_table(t, tmp.num_counters, newinfo, &ret);
932         if (!oldinfo)
933                 goto put_module;
934
935         /* Update module usage count based on number of rules */
936         duprintf("do_replace: oldnum=%u, initnum=%u, newnum=%u\n",
937                 oldinfo->number, oldinfo->initial_entries, newinfo->number);
938         if ((oldinfo->number > oldinfo->initial_entries) || 
939             (newinfo->number <= oldinfo->initial_entries)) 
940                 module_put(t->me);
941         if ((oldinfo->number > oldinfo->initial_entries) &&
942             (newinfo->number <= oldinfo->initial_entries))
943                 module_put(t->me);
944
945         /* Get the old counters. */
946         get_counters(oldinfo, counters);
947         /* Decrease module usage counts and free resource */
948         ARPT_ENTRY_ITERATE(oldinfo->entries, oldinfo->size, cleanup_entry,NULL);
949         vfree(oldinfo);
950         if (copy_to_user(tmp.counters, counters,
951                          sizeof(struct arpt_counters) * tmp.num_counters) != 0)
952                 ret = -EFAULT;
953         vfree(counters);
954         up(&arpt_mutex);
955         return ret;
956
957  put_module:
958         module_put(t->me);
959  free_newinfo_counters_untrans_unlock:
960         up(&arpt_mutex);
961  free_newinfo_counters_untrans:
962         ARPT_ENTRY_ITERATE(newinfo->entries, newinfo->size, cleanup_entry, NULL);
963  free_newinfo_counters:
964         vfree(counters);
965  free_newinfo:
966         vfree(newinfo);
967         return ret;
968 }
969
970 /* We're lazy, and add to the first CPU; overflow works its fey magic
971  * and everything is OK.
972  */
973 static inline int add_counter_to_entry(struct arpt_entry *e,
974                                        const struct arpt_counters addme[],
975                                        unsigned int *i)
976 {
977
978         ADD_COUNTER(e->counters, addme[*i].bcnt, addme[*i].pcnt);
979
980         (*i)++;
981         return 0;
982 }
983
984 static int do_add_counters(void __user *user, unsigned int len)
985 {
986         unsigned int i;
987         struct arpt_counters_info tmp, *paddc;
988         struct arpt_table *t;
989         int ret;
990
991         if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
992                 return -EFAULT;
993
994         if (len != sizeof(tmp) + tmp.num_counters*sizeof(struct arpt_counters))
995                 return -EINVAL;
996
997         paddc = vmalloc(len);
998         if (!paddc)
999                 return -ENOMEM;
1000
1001         if (copy_from_user(paddc, user, len) != 0) {
1002                 ret = -EFAULT;
1003                 goto free;
1004         }
1005
1006         t = arpt_find_table_lock(tmp.name, &ret, &arpt_mutex);
1007         if (!t)
1008                 goto free;
1009
1010         write_lock_bh(&t->lock);
1011         if (t->private->number != paddc->num_counters) {
1012                 ret = -EINVAL;
1013                 goto unlock_up_free;
1014         }
1015
1016         i = 0;
1017         ARPT_ENTRY_ITERATE(t->private->entries,
1018                            t->private->size,
1019                            add_counter_to_entry,
1020                            paddc->counters,
1021                            &i);
1022  unlock_up_free:
1023         write_unlock_bh(&t->lock);
1024         up(&arpt_mutex);
1025  free:
1026         vfree(paddc);
1027
1028         return ret;
1029 }
1030
1031 static int do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
1032 {
1033         int ret;
1034
1035         if (!capable(CAP_NET_ADMIN))
1036                 return -EPERM;
1037
1038         switch (cmd) {
1039         case ARPT_SO_SET_REPLACE:
1040                 ret = do_replace(user, len);
1041                 break;
1042
1043         case ARPT_SO_SET_ADD_COUNTERS:
1044                 ret = do_add_counters(user, len);
1045                 break;
1046
1047         default:
1048                 duprintf("do_arpt_set_ctl:  unknown request %i\n", cmd);
1049                 ret = -EINVAL;
1050         }
1051
1052         return ret;
1053 }
1054
1055 static int do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
1056 {
1057         int ret;
1058
1059         if (!capable(CAP_NET_ADMIN))
1060                 return -EPERM;
1061
1062         switch (cmd) {
1063         case ARPT_SO_GET_INFO: {
1064                 char name[ARPT_TABLE_MAXNAMELEN];
1065                 struct arpt_table *t;
1066
1067                 if (*len != sizeof(struct arpt_getinfo)) {
1068                         duprintf("length %u != %Zu\n", *len,
1069                                  sizeof(struct arpt_getinfo));
1070                         ret = -EINVAL;
1071                         break;
1072                 }
1073
1074                 if (copy_from_user(name, user, sizeof(name)) != 0) {
1075                         ret = -EFAULT;
1076                         break;
1077                 }
1078                 name[ARPT_TABLE_MAXNAMELEN-1] = '\0';
1079                 t = arpt_find_table_lock(name, &ret, &arpt_mutex);
1080                 if (t) {
1081                         struct arpt_getinfo info;
1082
1083                         info.valid_hooks = t->valid_hooks;
1084                         memcpy(info.hook_entry, t->private->hook_entry,
1085                                sizeof(info.hook_entry));
1086                         memcpy(info.underflow, t->private->underflow,
1087                                sizeof(info.underflow));
1088                         info.num_entries = t->private->number;
1089                         info.size = t->private->size;
1090                         strcpy(info.name, name);
1091
1092                         if (copy_to_user(user, &info, *len) != 0)
1093                                 ret = -EFAULT;
1094                         else
1095                                 ret = 0;
1096
1097                         up(&arpt_mutex);
1098                 }
1099         }
1100         break;
1101
1102         case ARPT_SO_GET_ENTRIES: {
1103                 struct arpt_get_entries get;
1104
1105                 if (*len < sizeof(get)) {
1106                         duprintf("get_entries: %u < %Zu\n", *len, sizeof(get));
1107                         ret = -EINVAL;
1108                 } else if (copy_from_user(&get, user, sizeof(get)) != 0) {
1109                         ret = -EFAULT;
1110                 } else if (*len != sizeof(struct arpt_get_entries) + get.size) {
1111                         duprintf("get_entries: %u != %Zu\n", *len,
1112                                  sizeof(struct arpt_get_entries) + get.size);
1113                         ret = -EINVAL;
1114                 } else
1115                         ret = get_entries(&get, user);
1116                 break;
1117         }
1118
1119         default:
1120                 duprintf("do_arpt_get_ctl: unknown request %i\n", cmd);
1121                 ret = -EINVAL;
1122         }
1123
1124         return ret;
1125 }
1126
1127 /* Registration hooks for targets. */
1128 int arpt_register_target(struct arpt_target *target)
1129 {
1130         int ret;
1131
1132         ret = down_interruptible(&arpt_mutex);
1133         if (ret != 0)
1134                 return ret;
1135
1136         if (!list_named_insert(&arpt_target, target)) {
1137                 duprintf("arpt_register_target: `%s' already in list!\n",
1138                          target->name);
1139                 ret = -EINVAL;
1140         }
1141         up(&arpt_mutex);
1142         return ret;
1143 }
1144
1145 void arpt_unregister_target(struct arpt_target *target)
1146 {
1147         down(&arpt_mutex);
1148         LIST_DELETE(&arpt_target, target);
1149         up(&arpt_mutex);
1150 }
1151
1152 int arpt_register_table(struct arpt_table *table,
1153                         const struct arpt_replace *repl)
1154 {
1155         int ret;
1156         struct arpt_table_info *newinfo;
1157         static struct arpt_table_info bootstrap
1158                 = { 0, 0, 0, { 0 }, { 0 }, { } };
1159
1160         newinfo = vmalloc(sizeof(struct arpt_table_info)
1161                           + SMP_ALIGN(repl->size) * num_possible_cpus());
1162         if (!newinfo) {
1163                 ret = -ENOMEM;
1164                 return ret;
1165         }
1166         memcpy(newinfo->entries, repl->entries, repl->size);
1167
1168         ret = translate_table(table->name, table->valid_hooks,
1169                               newinfo, repl->size,
1170                               repl->num_entries,
1171                               repl->hook_entry,
1172                               repl->underflow);
1173         duprintf("arpt_register_table: translate table gives %d\n", ret);
1174         if (ret != 0) {
1175                 vfree(newinfo);
1176                 return ret;
1177         }
1178
1179         ret = down_interruptible(&arpt_mutex);
1180         if (ret != 0) {
1181                 vfree(newinfo);
1182                 return ret;
1183         }
1184
1185         /* Don't autoload: we'd eat our tail... */
1186         if (list_named_find(&arpt_tables, table->name)) {
1187                 ret = -EEXIST;
1188                 goto free_unlock;
1189         }
1190
1191         /* Simplifies replace_table code. */
1192         table->private = &bootstrap;
1193         if (!replace_table(table, 0, newinfo, &ret))
1194                 goto free_unlock;
1195
1196         duprintf("table->private->number = %u\n",
1197                  table->private->number);
1198         
1199         /* save number of initial entries */
1200         table->private->initial_entries = table->private->number;
1201
1202         rwlock_init(&table->lock);
1203         list_prepend(&arpt_tables, table);
1204
1205  unlock:
1206         up(&arpt_mutex);
1207         return ret;
1208
1209  free_unlock:
1210         vfree(newinfo);
1211         goto unlock;
1212 }
1213
1214 void arpt_unregister_table(struct arpt_table *table)
1215 {
1216         down(&arpt_mutex);
1217         LIST_DELETE(&arpt_tables, table);
1218         up(&arpt_mutex);
1219
1220         /* Decrease module usage counts and free resources */
1221         ARPT_ENTRY_ITERATE(table->private->entries, table->private->size,
1222                            cleanup_entry, NULL);
1223         vfree(table->private);
1224 }
1225
1226 /* The built-in targets: standard (NULL) and error. */
1227 static struct arpt_target arpt_standard_target = {
1228         .name           = ARPT_STANDARD_TARGET,
1229 };
1230
1231 static struct arpt_target arpt_error_target = {
1232         .name           = ARPT_ERROR_TARGET,
1233         .target         = arpt_error,
1234 };
1235
1236 static struct nf_sockopt_ops arpt_sockopts = {
1237         .pf             = PF_INET,
1238         .set_optmin     = ARPT_BASE_CTL,
1239         .set_optmax     = ARPT_SO_SET_MAX+1,
1240         .set            = do_arpt_set_ctl,
1241         .get_optmin     = ARPT_BASE_CTL,
1242         .get_optmax     = ARPT_SO_GET_MAX+1,
1243         .get            = do_arpt_get_ctl,
1244 };
1245
1246 #ifdef CONFIG_PROC_FS
1247 static inline int print_name(const struct arpt_table *t,
1248                              off_t start_offset, char *buffer, int length,
1249                              off_t *pos, unsigned int *count)
1250 {
1251         if ((*count)++ >= start_offset) {
1252                 unsigned int namelen;
1253
1254                 namelen = sprintf(buffer + *pos, "%s\n", t->name);
1255                 if (*pos + namelen > length) {
1256                         /* Stop iterating */
1257                         return 1;
1258                 }
1259                 *pos += namelen;
1260         }
1261         return 0;
1262 }
1263
1264 static int arpt_get_tables(char *buffer, char **start, off_t offset, int length)
1265 {
1266         off_t pos = 0;
1267         unsigned int count = 0;
1268
1269         if (down_interruptible(&arpt_mutex) != 0)
1270                 return 0;
1271
1272         LIST_FIND(&arpt_tables, print_name, struct arpt_table *,
1273                   offset, buffer, length, &pos, &count);
1274
1275         up(&arpt_mutex);
1276
1277         /* `start' hack - see fs/proc/generic.c line ~105 */
1278         *start=(char *)((unsigned long)count-offset);
1279         return pos;
1280 }
1281 #endif /*CONFIG_PROC_FS*/
1282
1283 static int __init init(void)
1284 {
1285         int ret;
1286
1287         /* Noone else will be downing sem now, so we won't sleep */
1288         down(&arpt_mutex);
1289         list_append(&arpt_target, &arpt_standard_target);
1290         list_append(&arpt_target, &arpt_error_target);
1291         up(&arpt_mutex);
1292
1293         /* Register setsockopt */
1294         ret = nf_register_sockopt(&arpt_sockopts);
1295         if (ret < 0) {
1296                 duprintf("Unable to register sockopts.\n");
1297                 return ret;
1298         }
1299
1300 #ifdef CONFIG_PROC_FS
1301         {
1302                 struct proc_dir_entry *proc;
1303
1304                 proc = proc_net_create("arp_tables_names", 0, arpt_get_tables);
1305                 if (!proc) {
1306                         nf_unregister_sockopt(&arpt_sockopts);
1307                         return -ENOMEM;
1308                 }
1309                 proc->owner = THIS_MODULE;
1310         }
1311 #endif
1312
1313         printk("arp_tables: (C) 2002 David S. Miller\n");
1314         return 0;
1315 }
1316
1317 static void __exit fini(void)
1318 {
1319         nf_unregister_sockopt(&arpt_sockopts);
1320 #ifdef CONFIG_PROC_FS
1321         proc_net_remove("arp_tables_names");
1322 #endif
1323 }
1324
1325 EXPORT_SYMBOL(arpt_register_table);
1326 EXPORT_SYMBOL(arpt_unregister_table);
1327 EXPORT_SYMBOL(arpt_do_table);
1328 EXPORT_SYMBOL(arpt_register_target);
1329 EXPORT_SYMBOL(arpt_unregister_target);
1330
1331 module_init(init);
1332 module_exit(fini);