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TOMOYO Linux Cross Reference
Linux/net/ipv4/netfilter/arp_tables.c

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  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  * Copyright (C) 2006-2009 Patrick McHardy <kaber@trash.net>
 10  *
 11  */
 12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 13 #include <linux/kernel.h>
 14 #include <linux/skbuff.h>
 15 #include <linux/netdevice.h>
 16 #include <linux/capability.h>
 17 #include <linux/if_arp.h>
 18 #include <linux/kmod.h>
 19 #include <linux/vmalloc.h>
 20 #include <linux/proc_fs.h>
 21 #include <linux/module.h>
 22 #include <linux/init.h>
 23 #include <linux/mutex.h>
 24 #include <linux/err.h>
 25 #include <net/compat.h>
 26 #include <net/sock.h>
 27 #include <linux/uaccess.h>
 28 
 29 #include <linux/netfilter/x_tables.h>
 30 #include <linux/netfilter_arp/arp_tables.h>
 31 #include "../../netfilter/xt_repldata.h"
 32 
 33 MODULE_LICENSE("GPL");
 34 MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
 35 MODULE_DESCRIPTION("arptables core");
 36 
 37 void *arpt_alloc_initial_table(const struct xt_table *info)
 38 {
 39         return xt_alloc_initial_table(arpt, ARPT);
 40 }
 41 EXPORT_SYMBOL_GPL(arpt_alloc_initial_table);
 42 
 43 static inline int arp_devaddr_compare(const struct arpt_devaddr_info *ap,
 44                                       const char *hdr_addr, int len)
 45 {
 46         int i, ret;
 47 
 48         if (len > ARPT_DEV_ADDR_LEN_MAX)
 49                 len = ARPT_DEV_ADDR_LEN_MAX;
 50 
 51         ret = 0;
 52         for (i = 0; i < len; i++)
 53                 ret |= (hdr_addr[i] ^ ap->addr[i]) & ap->mask[i];
 54 
 55         return ret != 0;
 56 }
 57 
 58 /*
 59  * Unfortunately, _b and _mask are not aligned to an int (or long int)
 60  * Some arches dont care, unrolling the loop is a win on them.
 61  * For other arches, we only have a 16bit alignement.
 62  */
 63 static unsigned long ifname_compare(const char *_a, const char *_b, const char *_mask)
 64 {
 65 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
 66         unsigned long ret = ifname_compare_aligned(_a, _b, _mask);
 67 #else
 68         unsigned long ret = 0;
 69         const u16 *a = (const u16 *)_a;
 70         const u16 *b = (const u16 *)_b;
 71         const u16 *mask = (const u16 *)_mask;
 72         int i;
 73 
 74         for (i = 0; i < IFNAMSIZ/sizeof(u16); i++)
 75                 ret |= (a[i] ^ b[i]) & mask[i];
 76 #endif
 77         return ret;
 78 }
 79 
 80 /* Returns whether packet matches rule or not. */
 81 static inline int arp_packet_match(const struct arphdr *arphdr,
 82                                    struct net_device *dev,
 83                                    const char *indev,
 84                                    const char *outdev,
 85                                    const struct arpt_arp *arpinfo)
 86 {
 87         const char *arpptr = (char *)(arphdr + 1);
 88         const char *src_devaddr, *tgt_devaddr;
 89         __be32 src_ipaddr, tgt_ipaddr;
 90         long ret;
 91 
 92         if (NF_INVF(arpinfo, ARPT_INV_ARPOP,
 93                     (arphdr->ar_op & arpinfo->arpop_mask) != arpinfo->arpop))
 94                 return 0;
 95 
 96         if (NF_INVF(arpinfo, ARPT_INV_ARPHRD,
 97                     (arphdr->ar_hrd & arpinfo->arhrd_mask) != arpinfo->arhrd))
 98                 return 0;
 99 
100         if (NF_INVF(arpinfo, ARPT_INV_ARPPRO,
101                     (arphdr->ar_pro & arpinfo->arpro_mask) != arpinfo->arpro))
102                 return 0;
103 
104         if (NF_INVF(arpinfo, ARPT_INV_ARPHLN,
105                     (arphdr->ar_hln & arpinfo->arhln_mask) != arpinfo->arhln))
106                 return 0;
107 
108         src_devaddr = arpptr;
109         arpptr += dev->addr_len;
110         memcpy(&src_ipaddr, arpptr, sizeof(u32));
111         arpptr += sizeof(u32);
112         tgt_devaddr = arpptr;
113         arpptr += dev->addr_len;
114         memcpy(&tgt_ipaddr, arpptr, sizeof(u32));
115 
116         if (NF_INVF(arpinfo, ARPT_INV_SRCDEVADDR,
117                     arp_devaddr_compare(&arpinfo->src_devaddr, src_devaddr,
118                                         dev->addr_len)) ||
119             NF_INVF(arpinfo, ARPT_INV_TGTDEVADDR,
120                     arp_devaddr_compare(&arpinfo->tgt_devaddr, tgt_devaddr,
121                                         dev->addr_len)))
122                 return 0;
123 
124         if (NF_INVF(arpinfo, ARPT_INV_SRCIP,
125                     (src_ipaddr & arpinfo->smsk.s_addr) != arpinfo->src.s_addr) ||
126             NF_INVF(arpinfo, ARPT_INV_TGTIP,
127                     (tgt_ipaddr & arpinfo->tmsk.s_addr) != arpinfo->tgt.s_addr))
128                 return 0;
129 
130         /* Look for ifname matches.  */
131         ret = ifname_compare(indev, arpinfo->iniface, arpinfo->iniface_mask);
132 
133         if (NF_INVF(arpinfo, ARPT_INV_VIA_IN, ret != 0))
134                 return 0;
135 
136         ret = ifname_compare(outdev, arpinfo->outiface, arpinfo->outiface_mask);
137 
138         if (NF_INVF(arpinfo, ARPT_INV_VIA_OUT, ret != 0))
139                 return 0;
140 
141         return 1;
142 }
143 
144 static inline int arp_checkentry(const struct arpt_arp *arp)
145 {
146         if (arp->flags & ~ARPT_F_MASK)
147                 return 0;
148         if (arp->invflags & ~ARPT_INV_MASK)
149                 return 0;
150 
151         return 1;
152 }
153 
154 static unsigned int
155 arpt_error(struct sk_buff *skb, const struct xt_action_param *par)
156 {
157         net_err_ratelimited("arp_tables: error: '%s'\n",
158                             (const char *)par->targinfo);
159 
160         return NF_DROP;
161 }
162 
163 static inline const struct xt_entry_target *
164 arpt_get_target_c(const struct arpt_entry *e)
165 {
166         return arpt_get_target((struct arpt_entry *)e);
167 }
168 
169 static inline struct arpt_entry *
170 get_entry(const void *base, unsigned int offset)
171 {
172         return (struct arpt_entry *)(base + offset);
173 }
174 
175 static inline
176 struct arpt_entry *arpt_next_entry(const struct arpt_entry *entry)
177 {
178         return (void *)entry + entry->next_offset;
179 }
180 
181 unsigned int arpt_do_table(struct sk_buff *skb,
182                            const struct nf_hook_state *state,
183                            struct xt_table *table)
184 {
185         unsigned int hook = state->hook;
186         static const char nulldevname[IFNAMSIZ] __attribute__((aligned(sizeof(long))));
187         unsigned int verdict = NF_DROP;
188         const struct arphdr *arp;
189         struct arpt_entry *e, **jumpstack;
190         const char *indev, *outdev;
191         const void *table_base;
192         unsigned int cpu, stackidx = 0;
193         const struct xt_table_info *private;
194         struct xt_action_param acpar;
195         unsigned int addend;
196 
197         if (!pskb_may_pull(skb, arp_hdr_len(skb->dev)))
198                 return NF_DROP;
199 
200         indev = state->in ? state->in->name : nulldevname;
201         outdev = state->out ? state->out->name : nulldevname;
202 
203         local_bh_disable();
204         addend = xt_write_recseq_begin();
205         private = READ_ONCE(table->private); /* Address dependency. */
206         cpu     = smp_processor_id();
207         table_base = private->entries;
208         jumpstack  = (struct arpt_entry **)private->jumpstack[cpu];
209 
210         /* No TEE support for arptables, so no need to switch to alternate
211          * stack.  All targets that reenter must return absolute verdicts.
212          */
213         e = get_entry(table_base, private->hook_entry[hook]);
214 
215         acpar.state   = state;
216         acpar.hotdrop = false;
217 
218         arp = arp_hdr(skb);
219         do {
220                 const struct xt_entry_target *t;
221                 struct xt_counters *counter;
222 
223                 if (!arp_packet_match(arp, skb->dev, indev, outdev, &e->arp)) {
224                         e = arpt_next_entry(e);
225                         continue;
226                 }
227 
228                 counter = xt_get_this_cpu_counter(&e->counters);
229                 ADD_COUNTER(*counter, arp_hdr_len(skb->dev), 1);
230 
231                 t = arpt_get_target_c(e);
232 
233                 /* Standard target? */
234                 if (!t->u.kernel.target->target) {
235                         int v;
236 
237                         v = ((struct xt_standard_target *)t)->verdict;
238                         if (v < 0) {
239                                 /* Pop from stack? */
240                                 if (v != XT_RETURN) {
241                                         verdict = (unsigned int)(-v) - 1;
242                                         break;
243                                 }
244                                 if (stackidx == 0) {
245                                         e = get_entry(table_base,
246                                                       private->underflow[hook]);
247                                 } else {
248                                         e = jumpstack[--stackidx];
249                                         e = arpt_next_entry(e);
250                                 }
251                                 continue;
252                         }
253                         if (table_base + v
254                             != arpt_next_entry(e)) {
255                                 if (unlikely(stackidx >= private->stacksize)) {
256                                         verdict = NF_DROP;
257                                         break;
258                                 }
259                                 jumpstack[stackidx++] = e;
260                         }
261 
262                         e = get_entry(table_base, v);
263                         continue;
264                 }
265 
266                 acpar.target   = t->u.kernel.target;
267                 acpar.targinfo = t->data;
268                 verdict = t->u.kernel.target->target(skb, &acpar);
269 
270                 if (verdict == XT_CONTINUE) {
271                         /* Target might have changed stuff. */
272                         arp = arp_hdr(skb);
273                         e = arpt_next_entry(e);
274                 } else {
275                         /* Verdict */
276                         break;
277                 }
278         } while (!acpar.hotdrop);
279         xt_write_recseq_end(addend);
280         local_bh_enable();
281 
282         if (acpar.hotdrop)
283                 return NF_DROP;
284         else
285                 return verdict;
286 }
287 
288 /* All zeroes == unconditional rule. */
289 static inline bool unconditional(const struct arpt_entry *e)
290 {
291         static const struct arpt_arp uncond;
292 
293         return e->target_offset == sizeof(struct arpt_entry) &&
294                memcmp(&e->arp, &uncond, sizeof(uncond)) == 0;
295 }
296 
297 /* Figures out from what hook each rule can be called: returns 0 if
298  * there are loops.  Puts hook bitmask in comefrom.
299  */
300 static int mark_source_chains(const struct xt_table_info *newinfo,
301                               unsigned int valid_hooks, void *entry0,
302                               unsigned int *offsets)
303 {
304         unsigned int hook;
305 
306         /* No recursion; use packet counter to save back ptrs (reset
307          * to 0 as we leave), and comefrom to save source hook bitmask.
308          */
309         for (hook = 0; hook < NF_ARP_NUMHOOKS; hook++) {
310                 unsigned int pos = newinfo->hook_entry[hook];
311                 struct arpt_entry *e = entry0 + pos;
312 
313                 if (!(valid_hooks & (1 << hook)))
314                         continue;
315 
316                 /* Set initial back pointer. */
317                 e->counters.pcnt = pos;
318 
319                 for (;;) {
320                         const struct xt_standard_target *t
321                                 = (void *)arpt_get_target_c(e);
322                         int visited = e->comefrom & (1 << hook);
323 
324                         if (e->comefrom & (1 << NF_ARP_NUMHOOKS))
325                                 return 0;
326 
327                         e->comefrom
328                                 |= ((1 << hook) | (1 << NF_ARP_NUMHOOKS));
329 
330                         /* Unconditional return/END. */
331                         if ((unconditional(e) &&
332                              (strcmp(t->target.u.user.name,
333                                      XT_STANDARD_TARGET) == 0) &&
334                              t->verdict < 0) || visited) {
335                                 unsigned int oldpos, size;
336 
337                                 /* Return: backtrack through the last
338                                  * big jump.
339                                  */
340                                 do {
341                                         e->comefrom ^= (1<<NF_ARP_NUMHOOKS);
342                                         oldpos = pos;
343                                         pos = e->counters.pcnt;
344                                         e->counters.pcnt = 0;
345 
346                                         /* We're at the start. */
347                                         if (pos == oldpos)
348                                                 goto next;
349 
350                                         e = entry0 + pos;
351                                 } while (oldpos == pos + e->next_offset);
352 
353                                 /* Move along one */
354                                 size = e->next_offset;
355                                 e = entry0 + pos + size;
356                                 if (pos + size >= newinfo->size)
357                                         return 0;
358                                 e->counters.pcnt = pos;
359                                 pos += size;
360                         } else {
361                                 int newpos = t->verdict;
362 
363                                 if (strcmp(t->target.u.user.name,
364                                            XT_STANDARD_TARGET) == 0 &&
365                                     newpos >= 0) {
366                                         /* This a jump; chase it. */
367                                         if (!xt_find_jump_offset(offsets, newpos,
368                                                                  newinfo->number))
369                                                 return 0;
370                                 } else {
371                                         /* ... this is a fallthru */
372                                         newpos = pos + e->next_offset;
373                                         if (newpos >= newinfo->size)
374                                                 return 0;
375                                 }
376                                 e = entry0 + newpos;
377                                 e->counters.pcnt = pos;
378                                 pos = newpos;
379                         }
380                 }
381 next:           ;
382         }
383         return 1;
384 }
385 
386 static inline int check_target(struct arpt_entry *e, const char *name)
387 {
388         struct xt_entry_target *t = arpt_get_target(e);
389         struct xt_tgchk_param par = {
390                 .table     = name,
391                 .entryinfo = e,
392                 .target    = t->u.kernel.target,
393                 .targinfo  = t->data,
394                 .hook_mask = e->comefrom,
395                 .family    = NFPROTO_ARP,
396         };
397 
398         return xt_check_target(&par, t->u.target_size - sizeof(*t), 0, false);
399 }
400 
401 static inline int
402 find_check_entry(struct arpt_entry *e, const char *name, unsigned int size,
403                  struct xt_percpu_counter_alloc_state *alloc_state)
404 {
405         struct xt_entry_target *t;
406         struct xt_target *target;
407         int ret;
408 
409         if (!xt_percpu_counter_alloc(alloc_state, &e->counters))
410                 return -ENOMEM;
411 
412         t = arpt_get_target(e);
413         target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
414                                         t->u.user.revision);
415         if (IS_ERR(target)) {
416                 ret = PTR_ERR(target);
417                 goto out;
418         }
419         t->u.kernel.target = target;
420 
421         ret = check_target(e, name);
422         if (ret)
423                 goto err;
424         return 0;
425 err:
426         module_put(t->u.kernel.target->me);
427 out:
428         xt_percpu_counter_free(&e->counters);
429 
430         return ret;
431 }
432 
433 static bool check_underflow(const struct arpt_entry *e)
434 {
435         const struct xt_entry_target *t;
436         unsigned int verdict;
437 
438         if (!unconditional(e))
439                 return false;
440         t = arpt_get_target_c(e);
441         if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
442                 return false;
443         verdict = ((struct xt_standard_target *)t)->verdict;
444         verdict = -verdict - 1;
445         return verdict == NF_DROP || verdict == NF_ACCEPT;
446 }
447 
448 static inline int check_entry_size_and_hooks(struct arpt_entry *e,
449                                              struct xt_table_info *newinfo,
450                                              const unsigned char *base,
451                                              const unsigned char *limit,
452                                              const unsigned int *hook_entries,
453                                              const unsigned int *underflows,
454                                              unsigned int valid_hooks)
455 {
456         unsigned int h;
457         int err;
458 
459         if ((unsigned long)e % __alignof__(struct arpt_entry) != 0 ||
460             (unsigned char *)e + sizeof(struct arpt_entry) >= limit ||
461             (unsigned char *)e + e->next_offset > limit)
462                 return -EINVAL;
463 
464         if (e->next_offset
465             < sizeof(struct arpt_entry) + sizeof(struct xt_entry_target))
466                 return -EINVAL;
467 
468         if (!arp_checkentry(&e->arp))
469                 return -EINVAL;
470 
471         err = xt_check_entry_offsets(e, e->elems, e->target_offset,
472                                      e->next_offset);
473         if (err)
474                 return err;
475 
476         /* Check hooks & underflows */
477         for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
478                 if (!(valid_hooks & (1 << h)))
479                         continue;
480                 if ((unsigned char *)e - base == hook_entries[h])
481                         newinfo->hook_entry[h] = hook_entries[h];
482                 if ((unsigned char *)e - base == underflows[h]) {
483                         if (!check_underflow(e))
484                                 return -EINVAL;
485 
486                         newinfo->underflow[h] = underflows[h];
487                 }
488         }
489 
490         /* Clear counters and comefrom */
491         e->counters = ((struct xt_counters) { 0, 0 });
492         e->comefrom = 0;
493         return 0;
494 }
495 
496 static inline void cleanup_entry(struct arpt_entry *e)
497 {
498         struct xt_tgdtor_param par;
499         struct xt_entry_target *t;
500 
501         t = arpt_get_target(e);
502         par.target   = t->u.kernel.target;
503         par.targinfo = t->data;
504         par.family   = NFPROTO_ARP;
505         if (par.target->destroy != NULL)
506                 par.target->destroy(&par);
507         module_put(par.target->me);
508         xt_percpu_counter_free(&e->counters);
509 }
510 
511 /* Checks and translates the user-supplied table segment (held in
512  * newinfo).
513  */
514 static int translate_table(struct xt_table_info *newinfo, void *entry0,
515                            const struct arpt_replace *repl)
516 {
517         struct xt_percpu_counter_alloc_state alloc_state = { 0 };
518         struct arpt_entry *iter;
519         unsigned int *offsets;
520         unsigned int i;
521         int ret = 0;
522 
523         newinfo->size = repl->size;
524         newinfo->number = repl->num_entries;
525 
526         /* Init all hooks to impossible value. */
527         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
528                 newinfo->hook_entry[i] = 0xFFFFFFFF;
529                 newinfo->underflow[i] = 0xFFFFFFFF;
530         }
531 
532         offsets = xt_alloc_entry_offsets(newinfo->number);
533         if (!offsets)
534                 return -ENOMEM;
535         i = 0;
536 
537         /* Walk through entries, checking offsets. */
538         xt_entry_foreach(iter, entry0, newinfo->size) {
539                 ret = check_entry_size_and_hooks(iter, newinfo, entry0,
540                                                  entry0 + repl->size,
541                                                  repl->hook_entry,
542                                                  repl->underflow,
543                                                  repl->valid_hooks);
544                 if (ret != 0)
545                         goto out_free;
546                 if (i < repl->num_entries)
547                         offsets[i] = (void *)iter - entry0;
548                 ++i;
549                 if (strcmp(arpt_get_target(iter)->u.user.name,
550                     XT_ERROR_TARGET) == 0)
551                         ++newinfo->stacksize;
552         }
553 
554         ret = -EINVAL;
555         if (i != repl->num_entries)
556                 goto out_free;
557 
558         ret = xt_check_table_hooks(newinfo, repl->valid_hooks);
559         if (ret)
560                 goto out_free;
561 
562         if (!mark_source_chains(newinfo, repl->valid_hooks, entry0, offsets)) {
563                 ret = -ELOOP;
564                 goto out_free;
565         }
566         kvfree(offsets);
567 
568         /* Finally, each sanity check must pass */
569         i = 0;
570         xt_entry_foreach(iter, entry0, newinfo->size) {
571                 ret = find_check_entry(iter, repl->name, repl->size,
572                                        &alloc_state);
573                 if (ret != 0)
574                         break;
575                 ++i;
576         }
577 
578         if (ret != 0) {
579                 xt_entry_foreach(iter, entry0, newinfo->size) {
580                         if (i-- == 0)
581                                 break;
582                         cleanup_entry(iter);
583                 }
584                 return ret;
585         }
586 
587         return ret;
588  out_free:
589         kvfree(offsets);
590         return ret;
591 }
592 
593 static void get_counters(const struct xt_table_info *t,
594                          struct xt_counters counters[])
595 {
596         struct arpt_entry *iter;
597         unsigned int cpu;
598         unsigned int i;
599 
600         for_each_possible_cpu(cpu) {
601                 seqcount_t *s = &per_cpu(xt_recseq, cpu);
602 
603                 i = 0;
604                 xt_entry_foreach(iter, t->entries, t->size) {
605                         struct xt_counters *tmp;
606                         u64 bcnt, pcnt;
607                         unsigned int start;
608 
609                         tmp = xt_get_per_cpu_counter(&iter->counters, cpu);
610                         do {
611                                 start = read_seqcount_begin(s);
612                                 bcnt = tmp->bcnt;
613                                 pcnt = tmp->pcnt;
614                         } while (read_seqcount_retry(s, start));
615 
616                         ADD_COUNTER(counters[i], bcnt, pcnt);
617                         ++i;
618                         cond_resched();
619                 }
620         }
621 }
622 
623 static void get_old_counters(const struct xt_table_info *t,
624                              struct xt_counters counters[])
625 {
626         struct arpt_entry *iter;
627         unsigned int cpu, i;
628 
629         for_each_possible_cpu(cpu) {
630                 i = 0;
631                 xt_entry_foreach(iter, t->entries, t->size) {
632                         struct xt_counters *tmp;
633 
634                         tmp = xt_get_per_cpu_counter(&iter->counters, cpu);
635                         ADD_COUNTER(counters[i], tmp->bcnt, tmp->pcnt);
636                         ++i;
637                 }
638                 cond_resched();
639         }
640 }
641 
642 static struct xt_counters *alloc_counters(const struct xt_table *table)
643 {
644         unsigned int countersize;
645         struct xt_counters *counters;
646         const struct xt_table_info *private = table->private;
647 
648         /* We need atomic snapshot of counters: rest doesn't change
649          * (other than comefrom, which userspace doesn't care
650          * about).
651          */
652         countersize = sizeof(struct xt_counters) * private->number;
653         counters = vzalloc(countersize);
654 
655         if (counters == NULL)
656                 return ERR_PTR(-ENOMEM);
657 
658         get_counters(private, counters);
659 
660         return counters;
661 }
662 
663 static int copy_entries_to_user(unsigned int total_size,
664                                 const struct xt_table *table,
665                                 void __user *userptr)
666 {
667         unsigned int off, num;
668         const struct arpt_entry *e;
669         struct xt_counters *counters;
670         struct xt_table_info *private = table->private;
671         int ret = 0;
672         void *loc_cpu_entry;
673 
674         counters = alloc_counters(table);
675         if (IS_ERR(counters))
676                 return PTR_ERR(counters);
677 
678         loc_cpu_entry = private->entries;
679 
680         /* FIXME: use iterator macros --RR */
681         /* ... then go back and fix counters and names */
682         for (off = 0, num = 0; off < total_size; off += e->next_offset, num++){
683                 const struct xt_entry_target *t;
684 
685                 e = loc_cpu_entry + off;
686                 if (copy_to_user(userptr + off, e, sizeof(*e))) {
687                         ret = -EFAULT;
688                         goto free_counters;
689                 }
690                 if (copy_to_user(userptr + off
691                                  + offsetof(struct arpt_entry, counters),
692                                  &counters[num],
693                                  sizeof(counters[num])) != 0) {
694                         ret = -EFAULT;
695                         goto free_counters;
696                 }
697 
698                 t = arpt_get_target_c(e);
699                 if (xt_target_to_user(t, userptr + off + e->target_offset)) {
700                         ret = -EFAULT;
701                         goto free_counters;
702                 }
703         }
704 
705  free_counters:
706         vfree(counters);
707         return ret;
708 }
709 
710 #ifdef CONFIG_COMPAT
711 static void compat_standard_from_user(void *dst, const void *src)
712 {
713         int v = *(compat_int_t *)src;
714 
715         if (v > 0)
716                 v += xt_compat_calc_jump(NFPROTO_ARP, v);
717         memcpy(dst, &v, sizeof(v));
718 }
719 
720 static int compat_standard_to_user(void __user *dst, const void *src)
721 {
722         compat_int_t cv = *(int *)src;
723 
724         if (cv > 0)
725                 cv -= xt_compat_calc_jump(NFPROTO_ARP, cv);
726         return copy_to_user(dst, &cv, sizeof(cv)) ? -EFAULT : 0;
727 }
728 
729 static int compat_calc_entry(const struct arpt_entry *e,
730                              const struct xt_table_info *info,
731                              const void *base, struct xt_table_info *newinfo)
732 {
733         const struct xt_entry_target *t;
734         unsigned int entry_offset;
735         int off, i, ret;
736 
737         off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
738         entry_offset = (void *)e - base;
739 
740         t = arpt_get_target_c(e);
741         off += xt_compat_target_offset(t->u.kernel.target);
742         newinfo->size -= off;
743         ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
744         if (ret)
745                 return ret;
746 
747         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
748                 if (info->hook_entry[i] &&
749                     (e < (struct arpt_entry *)(base + info->hook_entry[i])))
750                         newinfo->hook_entry[i] -= off;
751                 if (info->underflow[i] &&
752                     (e < (struct arpt_entry *)(base + info->underflow[i])))
753                         newinfo->underflow[i] -= off;
754         }
755         return 0;
756 }
757 
758 static int compat_table_info(const struct xt_table_info *info,
759                              struct xt_table_info *newinfo)
760 {
761         struct arpt_entry *iter;
762         const void *loc_cpu_entry;
763         int ret;
764 
765         if (!newinfo || !info)
766                 return -EINVAL;
767 
768         /* we dont care about newinfo->entries */
769         memcpy(newinfo, info, offsetof(struct xt_table_info, entries));
770         newinfo->initial_entries = 0;
771         loc_cpu_entry = info->entries;
772         ret = xt_compat_init_offsets(NFPROTO_ARP, info->number);
773         if (ret)
774                 return ret;
775         xt_entry_foreach(iter, loc_cpu_entry, info->size) {
776                 ret = compat_calc_entry(iter, info, loc_cpu_entry, newinfo);
777                 if (ret != 0)
778                         return ret;
779         }
780         return 0;
781 }
782 #endif
783 
784 static int get_info(struct net *net, void __user *user,
785                     const int *len, int compat)
786 {
787         char name[XT_TABLE_MAXNAMELEN];
788         struct xt_table *t;
789         int ret;
790 
791         if (*len != sizeof(struct arpt_getinfo))
792                 return -EINVAL;
793 
794         if (copy_from_user(name, user, sizeof(name)) != 0)
795                 return -EFAULT;
796 
797         name[XT_TABLE_MAXNAMELEN-1] = '\0';
798 #ifdef CONFIG_COMPAT
799         if (compat)
800                 xt_compat_lock(NFPROTO_ARP);
801 #endif
802         t = xt_request_find_table_lock(net, NFPROTO_ARP, name);
803         if (!IS_ERR(t)) {
804                 struct arpt_getinfo info;
805                 const struct xt_table_info *private = t->private;
806 #ifdef CONFIG_COMPAT
807                 struct xt_table_info tmp;
808 
809                 if (compat) {
810                         ret = compat_table_info(private, &tmp);
811                         xt_compat_flush_offsets(NFPROTO_ARP);
812                         private = &tmp;
813                 }
814 #endif
815                 memset(&info, 0, sizeof(info));
816                 info.valid_hooks = t->valid_hooks;
817                 memcpy(info.hook_entry, private->hook_entry,
818                        sizeof(info.hook_entry));
819                 memcpy(info.underflow, private->underflow,
820                        sizeof(info.underflow));
821                 info.num_entries = private->number;
822                 info.size = private->size;
823                 strcpy(info.name, name);
824 
825                 if (copy_to_user(user, &info, *len) != 0)
826                         ret = -EFAULT;
827                 else
828                         ret = 0;
829                 xt_table_unlock(t);
830                 module_put(t->me);
831         } else
832                 ret = PTR_ERR(t);
833 #ifdef CONFIG_COMPAT
834         if (compat)
835                 xt_compat_unlock(NFPROTO_ARP);
836 #endif
837         return ret;
838 }
839 
840 static int get_entries(struct net *net, struct arpt_get_entries __user *uptr,
841                        const int *len)
842 {
843         int ret;
844         struct arpt_get_entries get;
845         struct xt_table *t;
846 
847         if (*len < sizeof(get))
848                 return -EINVAL;
849         if (copy_from_user(&get, uptr, sizeof(get)) != 0)
850                 return -EFAULT;
851         if (*len != sizeof(struct arpt_get_entries) + get.size)
852                 return -EINVAL;
853 
854         get.name[sizeof(get.name) - 1] = '\0';
855 
856         t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
857         if (!IS_ERR(t)) {
858                 const struct xt_table_info *private = t->private;
859 
860                 if (get.size == private->size)
861                         ret = copy_entries_to_user(private->size,
862                                                    t, uptr->entrytable);
863                 else
864                         ret = -EAGAIN;
865 
866                 module_put(t->me);
867                 xt_table_unlock(t);
868         } else
869                 ret = PTR_ERR(t);
870 
871         return ret;
872 }
873 
874 static int __do_replace(struct net *net, const char *name,
875                         unsigned int valid_hooks,
876                         struct xt_table_info *newinfo,
877                         unsigned int num_counters,
878                         void __user *counters_ptr)
879 {
880         int ret;
881         struct xt_table *t;
882         struct xt_table_info *oldinfo;
883         struct xt_counters *counters;
884         void *loc_cpu_old_entry;
885         struct arpt_entry *iter;
886 
887         ret = 0;
888         counters = xt_counters_alloc(num_counters);
889         if (!counters) {
890                 ret = -ENOMEM;
891                 goto out;
892         }
893 
894         t = xt_request_find_table_lock(net, NFPROTO_ARP, name);
895         if (IS_ERR(t)) {
896                 ret = PTR_ERR(t);
897                 goto free_newinfo_counters_untrans;
898         }
899 
900         /* You lied! */
901         if (valid_hooks != t->valid_hooks) {
902                 ret = -EINVAL;
903                 goto put_module;
904         }
905 
906         oldinfo = xt_replace_table(t, num_counters, newinfo, &ret);
907         if (!oldinfo)
908                 goto put_module;
909 
910         /* Update module usage count based on number of rules */
911         if ((oldinfo->number > oldinfo->initial_entries) ||
912             (newinfo->number <= oldinfo->initial_entries))
913                 module_put(t->me);
914         if ((oldinfo->number > oldinfo->initial_entries) &&
915             (newinfo->number <= oldinfo->initial_entries))
916                 module_put(t->me);
917 
918         xt_table_unlock(t);
919 
920         get_old_counters(oldinfo, counters);
921 
922         /* Decrease module usage counts and free resource */
923         loc_cpu_old_entry = oldinfo->entries;
924         xt_entry_foreach(iter, loc_cpu_old_entry, oldinfo->size)
925                 cleanup_entry(iter);
926 
927         xt_free_table_info(oldinfo);
928         if (copy_to_user(counters_ptr, counters,
929                          sizeof(struct xt_counters) * num_counters) != 0) {
930                 /* Silent error, can't fail, new table is already in place */
931                 net_warn_ratelimited("arptables: counters copy to user failed while replacing table\n");
932         }
933         vfree(counters);
934         return ret;
935 
936  put_module:
937         module_put(t->me);
938         xt_table_unlock(t);
939  free_newinfo_counters_untrans:
940         vfree(counters);
941  out:
942         return ret;
943 }
944 
945 static int do_replace(struct net *net, const void __user *user,
946                       unsigned int len)
947 {
948         int ret;
949         struct arpt_replace tmp;
950         struct xt_table_info *newinfo;
951         void *loc_cpu_entry;
952         struct arpt_entry *iter;
953 
954         if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
955                 return -EFAULT;
956 
957         /* overflow check */
958         if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
959                 return -ENOMEM;
960         if (tmp.num_counters == 0)
961                 return -EINVAL;
962 
963         tmp.name[sizeof(tmp.name)-1] = 0;
964 
965         newinfo = xt_alloc_table_info(tmp.size);
966         if (!newinfo)
967                 return -ENOMEM;
968 
969         loc_cpu_entry = newinfo->entries;
970         if (copy_from_user(loc_cpu_entry, user + sizeof(tmp),
971                            tmp.size) != 0) {
972                 ret = -EFAULT;
973                 goto free_newinfo;
974         }
975 
976         ret = translate_table(newinfo, loc_cpu_entry, &tmp);
977         if (ret != 0)
978                 goto free_newinfo;
979 
980         ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
981                            tmp.num_counters, tmp.counters);
982         if (ret)
983                 goto free_newinfo_untrans;
984         return 0;
985 
986  free_newinfo_untrans:
987         xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
988                 cleanup_entry(iter);
989  free_newinfo:
990         xt_free_table_info(newinfo);
991         return ret;
992 }
993 
994 static int do_add_counters(struct net *net, const void __user *user,
995                            unsigned int len, int compat)
996 {
997         unsigned int i;
998         struct xt_counters_info tmp;
999         struct xt_counters *paddc;
1000         struct xt_table *t;
1001         const struct xt_table_info *private;
1002         int ret = 0;
1003         struct arpt_entry *iter;
1004         unsigned int addend;
1005 
1006         paddc = xt_copy_counters_from_user(user, len, &tmp, compat);
1007         if (IS_ERR(paddc))
1008                 return PTR_ERR(paddc);
1009 
1010         t = xt_find_table_lock(net, NFPROTO_ARP, tmp.name);
1011         if (IS_ERR(t)) {
1012                 ret = PTR_ERR(t);
1013                 goto free;
1014         }
1015 
1016         local_bh_disable();
1017         private = t->private;
1018         if (private->number != tmp.num_counters) {
1019                 ret = -EINVAL;
1020                 goto unlock_up_free;
1021         }
1022 
1023         i = 0;
1024 
1025         addend = xt_write_recseq_begin();
1026         xt_entry_foreach(iter,  private->entries, private->size) {
1027                 struct xt_counters *tmp;
1028 
1029                 tmp = xt_get_this_cpu_counter(&iter->counters);
1030                 ADD_COUNTER(*tmp, paddc[i].bcnt, paddc[i].pcnt);
1031                 ++i;
1032         }
1033         xt_write_recseq_end(addend);
1034  unlock_up_free:
1035         local_bh_enable();
1036         xt_table_unlock(t);
1037         module_put(t->me);
1038  free:
1039         vfree(paddc);
1040 
1041         return ret;
1042 }
1043 
1044 #ifdef CONFIG_COMPAT
1045 struct compat_arpt_replace {
1046         char                            name[XT_TABLE_MAXNAMELEN];
1047         u32                             valid_hooks;
1048         u32                             num_entries;
1049         u32                             size;
1050         u32                             hook_entry[NF_ARP_NUMHOOKS];
1051         u32                             underflow[NF_ARP_NUMHOOKS];
1052         u32                             num_counters;
1053         compat_uptr_t                   counters;
1054         struct compat_arpt_entry        entries[0];
1055 };
1056 
1057 static inline void compat_release_entry(struct compat_arpt_entry *e)
1058 {
1059         struct xt_entry_target *t;
1060 
1061         t = compat_arpt_get_target(e);
1062         module_put(t->u.kernel.target->me);
1063 }
1064 
1065 static int
1066 check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
1067                                   struct xt_table_info *newinfo,
1068                                   unsigned int *size,
1069                                   const unsigned char *base,
1070                                   const unsigned char *limit)
1071 {
1072         struct xt_entry_target *t;
1073         struct xt_target *target;
1074         unsigned int entry_offset;
1075         int ret, off;
1076 
1077         if ((unsigned long)e % __alignof__(struct compat_arpt_entry) != 0 ||
1078             (unsigned char *)e + sizeof(struct compat_arpt_entry) >= limit ||
1079             (unsigned char *)e + e->next_offset > limit)
1080                 return -EINVAL;
1081 
1082         if (e->next_offset < sizeof(struct compat_arpt_entry) +
1083                              sizeof(struct compat_xt_entry_target))
1084                 return -EINVAL;
1085 
1086         if (!arp_checkentry(&e->arp))
1087                 return -EINVAL;
1088 
1089         ret = xt_compat_check_entry_offsets(e, e->elems, e->target_offset,
1090                                             e->next_offset);
1091         if (ret)
1092                 return ret;
1093 
1094         off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1095         entry_offset = (void *)e - (void *)base;
1096 
1097         t = compat_arpt_get_target(e);
1098         target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
1099                                         t->u.user.revision);
1100         if (IS_ERR(target)) {
1101                 ret = PTR_ERR(target);
1102                 goto out;
1103         }
1104         t->u.kernel.target = target;
1105 
1106         off += xt_compat_target_offset(target);
1107         *size += off;
1108         ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
1109         if (ret)
1110                 goto release_target;
1111 
1112         return 0;
1113 
1114 release_target:
1115         module_put(t->u.kernel.target->me);
1116 out:
1117         return ret;
1118 }
1119 
1120 static void
1121 compat_copy_entry_from_user(struct compat_arpt_entry *e, void **dstptr,
1122                             unsigned int *size,
1123                             struct xt_table_info *newinfo, unsigned char *base)
1124 {
1125         struct xt_entry_target *t;
1126         struct arpt_entry *de;
1127         unsigned int origsize;
1128         int h;
1129 
1130         origsize = *size;
1131         de = *dstptr;
1132         memcpy(de, e, sizeof(struct arpt_entry));
1133         memcpy(&de->counters, &e->counters, sizeof(e->counters));
1134 
1135         *dstptr += sizeof(struct arpt_entry);
1136         *size += sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1137 
1138         de->target_offset = e->target_offset - (origsize - *size);
1139         t = compat_arpt_get_target(e);
1140         xt_compat_target_from_user(t, dstptr, size);
1141 
1142         de->next_offset = e->next_offset - (origsize - *size);
1143         for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
1144                 if ((unsigned char *)de - base < newinfo->hook_entry[h])
1145                         newinfo->hook_entry[h] -= origsize - *size;
1146                 if ((unsigned char *)de - base < newinfo->underflow[h])
1147                         newinfo->underflow[h] -= origsize - *size;
1148         }
1149 }
1150 
1151 static int translate_compat_table(struct xt_table_info **pinfo,
1152                                   void **pentry0,
1153                                   const struct compat_arpt_replace *compatr)
1154 {
1155         unsigned int i, j;
1156         struct xt_table_info *newinfo, *info;
1157         void *pos, *entry0, *entry1;
1158         struct compat_arpt_entry *iter0;
1159         struct arpt_replace repl;
1160         unsigned int size;
1161         int ret;
1162 
1163         info = *pinfo;
1164         entry0 = *pentry0;
1165         size = compatr->size;
1166         info->number = compatr->num_entries;
1167 
1168         j = 0;
1169         xt_compat_lock(NFPROTO_ARP);
1170         ret = xt_compat_init_offsets(NFPROTO_ARP, compatr->num_entries);
1171         if (ret)
1172                 goto out_unlock;
1173         /* Walk through entries, checking offsets. */
1174         xt_entry_foreach(iter0, entry0, compatr->size) {
1175                 ret = check_compat_entry_size_and_hooks(iter0, info, &size,
1176                                                         entry0,
1177                                                         entry0 + compatr->size);
1178                 if (ret != 0)
1179                         goto out_unlock;
1180                 ++j;
1181         }
1182 
1183         ret = -EINVAL;
1184         if (j != compatr->num_entries)
1185                 goto out_unlock;
1186 
1187         ret = -ENOMEM;
1188         newinfo = xt_alloc_table_info(size);
1189         if (!newinfo)
1190                 goto out_unlock;
1191 
1192         newinfo->number = compatr->num_entries;
1193         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1194                 newinfo->hook_entry[i] = compatr->hook_entry[i];
1195                 newinfo->underflow[i] = compatr->underflow[i];
1196         }
1197         entry1 = newinfo->entries;
1198         pos = entry1;
1199         size = compatr->size;
1200         xt_entry_foreach(iter0, entry0, compatr->size)
1201                 compat_copy_entry_from_user(iter0, &pos, &size,
1202                                             newinfo, entry1);
1203 
1204         /* all module references in entry0 are now gone */
1205 
1206         xt_compat_flush_offsets(NFPROTO_ARP);
1207         xt_compat_unlock(NFPROTO_ARP);
1208 
1209         memcpy(&repl, compatr, sizeof(*compatr));
1210 
1211         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1212                 repl.hook_entry[i] = newinfo->hook_entry[i];
1213                 repl.underflow[i] = newinfo->underflow[i];
1214         }
1215 
1216         repl.num_counters = 0;
1217         repl.counters = NULL;
1218         repl.size = newinfo->size;
1219         ret = translate_table(newinfo, entry1, &repl);
1220         if (ret)
1221                 goto free_newinfo;
1222 
1223         *pinfo = newinfo;
1224         *pentry0 = entry1;
1225         xt_free_table_info(info);
1226         return 0;
1227 
1228 free_newinfo:
1229         xt_free_table_info(newinfo);
1230         return ret;
1231 out_unlock:
1232         xt_compat_flush_offsets(NFPROTO_ARP);
1233         xt_compat_unlock(NFPROTO_ARP);
1234         xt_entry_foreach(iter0, entry0, compatr->size) {
1235                 if (j-- == 0)
1236                         break;
1237                 compat_release_entry(iter0);
1238         }
1239         return ret;
1240 }
1241 
1242 static int compat_do_replace(struct net *net, void __user *user,
1243                              unsigned int len)
1244 {
1245         int ret;
1246         struct compat_arpt_replace tmp;
1247         struct xt_table_info *newinfo;
1248         void *loc_cpu_entry;
1249         struct arpt_entry *iter;
1250 
1251         if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
1252                 return -EFAULT;
1253 
1254         /* overflow check */
1255         if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
1256                 return -ENOMEM;
1257         if (tmp.num_counters == 0)
1258                 return -EINVAL;
1259 
1260         tmp.name[sizeof(tmp.name)-1] = 0;
1261 
1262         newinfo = xt_alloc_table_info(tmp.size);
1263         if (!newinfo)
1264                 return -ENOMEM;
1265 
1266         loc_cpu_entry = newinfo->entries;
1267         if (copy_from_user(loc_cpu_entry, user + sizeof(tmp), tmp.size) != 0) {
1268                 ret = -EFAULT;
1269                 goto free_newinfo;
1270         }
1271 
1272         ret = translate_compat_table(&newinfo, &loc_cpu_entry, &tmp);
1273         if (ret != 0)
1274                 goto free_newinfo;
1275 
1276         ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
1277                            tmp.num_counters, compat_ptr(tmp.counters));
1278         if (ret)
1279                 goto free_newinfo_untrans;
1280         return 0;
1281 
1282  free_newinfo_untrans:
1283         xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
1284                 cleanup_entry(iter);
1285  free_newinfo:
1286         xt_free_table_info(newinfo);
1287         return ret;
1288 }
1289 
1290 static int compat_do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user,
1291                                   unsigned int len)
1292 {
1293         int ret;
1294 
1295         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1296                 return -EPERM;
1297 
1298         switch (cmd) {
1299         case ARPT_SO_SET_REPLACE:
1300                 ret = compat_do_replace(sock_net(sk), user, len);
1301                 break;
1302 
1303         case ARPT_SO_SET_ADD_COUNTERS:
1304                 ret = do_add_counters(sock_net(sk), user, len, 1);
1305                 break;
1306 
1307         default:
1308                 ret = -EINVAL;
1309         }
1310 
1311         return ret;
1312 }
1313 
1314 static int compat_copy_entry_to_user(struct arpt_entry *e, void __user **dstptr,
1315                                      compat_uint_t *size,
1316                                      struct xt_counters *counters,
1317                                      unsigned int i)
1318 {
1319         struct xt_entry_target *t;
1320         struct compat_arpt_entry __user *ce;
1321         u_int16_t target_offset, next_offset;
1322         compat_uint_t origsize;
1323         int ret;
1324 
1325         origsize = *size;
1326         ce = *dstptr;
1327         if (copy_to_user(ce, e, sizeof(struct arpt_entry)) != 0 ||
1328             copy_to_user(&ce->counters, &counters[i],
1329             sizeof(counters[i])) != 0)
1330                 return -EFAULT;
1331 
1332         *dstptr += sizeof(struct compat_arpt_entry);
1333         *size -= sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1334 
1335         target_offset = e->target_offset - (origsize - *size);
1336 
1337         t = arpt_get_target(e);
1338         ret = xt_compat_target_to_user(t, dstptr, size);
1339         if (ret)
1340                 return ret;
1341         next_offset = e->next_offset - (origsize - *size);
1342         if (put_user(target_offset, &ce->target_offset) != 0 ||
1343             put_user(next_offset, &ce->next_offset) != 0)
1344                 return -EFAULT;
1345         return 0;
1346 }
1347 
1348 static int compat_copy_entries_to_user(unsigned int total_size,
1349                                        struct xt_table *table,
1350                                        void __user *userptr)
1351 {
1352         struct xt_counters *counters;
1353         const struct xt_table_info *private = table->private;
1354         void __user *pos;
1355         unsigned int size;
1356         int ret = 0;
1357         unsigned int i = 0;
1358         struct arpt_entry *iter;
1359 
1360         counters = alloc_counters(table);
1361         if (IS_ERR(counters))
1362                 return PTR_ERR(counters);
1363 
1364         pos = userptr;
1365         size = total_size;
1366         xt_entry_foreach(iter, private->entries, total_size) {
1367                 ret = compat_copy_entry_to_user(iter, &pos,
1368                                                 &size, counters, i++);
1369                 if (ret != 0)
1370                         break;
1371         }
1372         vfree(counters);
1373         return ret;
1374 }
1375 
1376 struct compat_arpt_get_entries {
1377         char name[XT_TABLE_MAXNAMELEN];
1378         compat_uint_t size;
1379         struct compat_arpt_entry entrytable[0];
1380 };
1381 
1382 static int compat_get_entries(struct net *net,
1383                               struct compat_arpt_get_entries __user *uptr,
1384                               int *len)
1385 {
1386         int ret;
1387         struct compat_arpt_get_entries get;
1388         struct xt_table *t;
1389 
1390         if (*len < sizeof(get))
1391                 return -EINVAL;
1392         if (copy_from_user(&get, uptr, sizeof(get)) != 0)
1393                 return -EFAULT;
1394         if (*len != sizeof(struct compat_arpt_get_entries) + get.size)
1395                 return -EINVAL;
1396 
1397         get.name[sizeof(get.name) - 1] = '\0';
1398 
1399         xt_compat_lock(NFPROTO_ARP);
1400         t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
1401         if (!IS_ERR(t)) {
1402                 const struct xt_table_info *private = t->private;
1403                 struct xt_table_info info;
1404 
1405                 ret = compat_table_info(private, &info);
1406                 if (!ret && get.size == info.size) {
1407                         ret = compat_copy_entries_to_user(private->size,
1408                                                           t, uptr->entrytable);
1409                 } else if (!ret)
1410                         ret = -EAGAIN;
1411 
1412                 xt_compat_flush_offsets(NFPROTO_ARP);
1413                 module_put(t->me);
1414                 xt_table_unlock(t);
1415         } else
1416                 ret = PTR_ERR(t);
1417 
1418         xt_compat_unlock(NFPROTO_ARP);
1419         return ret;
1420 }
1421 
1422 static int do_arpt_get_ctl(struct sock *, int, void __user *, int *);
1423 
1424 static int compat_do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user,
1425                                   int *len)
1426 {
1427         int ret;
1428 
1429         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1430                 return -EPERM;
1431 
1432         switch (cmd) {
1433         case ARPT_SO_GET_INFO:
1434                 ret = get_info(sock_net(sk), user, len, 1);
1435                 break;
1436         case ARPT_SO_GET_ENTRIES:
1437                 ret = compat_get_entries(sock_net(sk), user, len);
1438                 break;
1439         default:
1440                 ret = do_arpt_get_ctl(sk, cmd, user, len);
1441         }
1442         return ret;
1443 }
1444 #endif
1445 
1446 static int do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
1447 {
1448         int ret;
1449 
1450         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1451                 return -EPERM;
1452 
1453         switch (cmd) {
1454         case ARPT_SO_SET_REPLACE:
1455                 ret = do_replace(sock_net(sk), user, len);
1456                 break;
1457 
1458         case ARPT_SO_SET_ADD_COUNTERS:
1459                 ret = do_add_counters(sock_net(sk), user, len, 0);
1460                 break;
1461 
1462         default:
1463                 ret = -EINVAL;
1464         }
1465 
1466         return ret;
1467 }
1468 
1469 static int do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
1470 {
1471         int ret;
1472 
1473         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1474                 return -EPERM;
1475 
1476         switch (cmd) {
1477         case ARPT_SO_GET_INFO:
1478                 ret = get_info(sock_net(sk), user, len, 0);
1479                 break;
1480 
1481         case ARPT_SO_GET_ENTRIES:
1482                 ret = get_entries(sock_net(sk), user, len);
1483                 break;
1484 
1485         case ARPT_SO_GET_REVISION_TARGET: {
1486                 struct xt_get_revision rev;
1487 
1488                 if (*len != sizeof(rev)) {
1489                         ret = -EINVAL;
1490                         break;
1491                 }
1492                 if (copy_from_user(&rev, user, sizeof(rev)) != 0) {
1493                         ret = -EFAULT;
1494                         break;
1495                 }
1496                 rev.name[sizeof(rev.name)-1] = 0;
1497 
1498                 try_then_request_module(xt_find_revision(NFPROTO_ARP, rev.name,
1499                                                          rev.revision, 1, &ret),
1500                                         "arpt_%s", rev.name);
1501                 break;
1502         }
1503 
1504         default:
1505                 ret = -EINVAL;
1506         }
1507 
1508         return ret;
1509 }
1510 
1511 static void __arpt_unregister_table(struct xt_table *table)
1512 {
1513         struct xt_table_info *private;
1514         void *loc_cpu_entry;
1515         struct module *table_owner = table->me;
1516         struct arpt_entry *iter;
1517 
1518         private = xt_unregister_table(table);
1519 
1520         /* Decrease module usage counts and free resources */
1521         loc_cpu_entry = private->entries;
1522         xt_entry_foreach(iter, loc_cpu_entry, private->size)
1523                 cleanup_entry(iter);
1524         if (private->number > private->initial_entries)
1525                 module_put(table_owner);
1526         xt_free_table_info(private);
1527 }
1528 
1529 int arpt_register_table(struct net *net,
1530                         const struct xt_table *table,
1531                         const struct arpt_replace *repl,
1532                         const struct nf_hook_ops *ops,
1533                         struct xt_table **res)
1534 {
1535         int ret;
1536         struct xt_table_info *newinfo;
1537         struct xt_table_info bootstrap = {0};
1538         void *loc_cpu_entry;
1539         struct xt_table *new_table;
1540 
1541         newinfo = xt_alloc_table_info(repl->size);
1542         if (!newinfo)
1543                 return -ENOMEM;
1544 
1545         loc_cpu_entry = newinfo->entries;
1546         memcpy(loc_cpu_entry, repl->entries, repl->size);
1547 
1548         ret = translate_table(newinfo, loc_cpu_entry, repl);
1549         if (ret != 0)
1550                 goto out_free;
1551 
1552         new_table = xt_register_table(net, table, &bootstrap, newinfo);
1553         if (IS_ERR(new_table)) {
1554                 ret = PTR_ERR(new_table);
1555                 goto out_free;
1556         }
1557 
1558         /* set res now, will see skbs right after nf_register_net_hooks */
1559         WRITE_ONCE(*res, new_table);
1560 
1561         ret = nf_register_net_hooks(net, ops, hweight32(table->valid_hooks));
1562         if (ret != 0) {
1563                 __arpt_unregister_table(new_table);
1564                 *res = NULL;
1565         }
1566 
1567         return ret;
1568 
1569 out_free:
1570         xt_free_table_info(newinfo);
1571         return ret;
1572 }
1573 
1574 void arpt_unregister_table(struct net *net, struct xt_table *table,
1575                            const struct nf_hook_ops *ops)
1576 {
1577         nf_unregister_net_hooks(net, ops, hweight32(table->valid_hooks));
1578         __arpt_unregister_table(table);
1579 }
1580 
1581 /* The built-in targets: standard (NULL) and error. */
1582 static struct xt_target arpt_builtin_tg[] __read_mostly = {
1583         {
1584                 .name             = XT_STANDARD_TARGET,
1585                 .targetsize       = sizeof(int),
1586                 .family           = NFPROTO_ARP,
1587 #ifdef CONFIG_COMPAT
1588                 .compatsize       = sizeof(compat_int_t),
1589                 .compat_from_user = compat_standard_from_user,
1590                 .compat_to_user   = compat_standard_to_user,
1591 #endif
1592         },
1593         {
1594                 .name             = XT_ERROR_TARGET,
1595                 .target           = arpt_error,
1596                 .targetsize       = XT_FUNCTION_MAXNAMELEN,
1597                 .family           = NFPROTO_ARP,
1598         },
1599 };
1600 
1601 static struct nf_sockopt_ops arpt_sockopts = {
1602         .pf             = PF_INET,
1603         .set_optmin     = ARPT_BASE_CTL,
1604         .set_optmax     = ARPT_SO_SET_MAX+1,
1605         .set            = do_arpt_set_ctl,
1606 #ifdef CONFIG_COMPAT
1607         .compat_set     = compat_do_arpt_set_ctl,
1608 #endif
1609         .get_optmin     = ARPT_BASE_CTL,
1610         .get_optmax     = ARPT_SO_GET_MAX+1,
1611         .get            = do_arpt_get_ctl,
1612 #ifdef CONFIG_COMPAT
1613         .compat_get     = compat_do_arpt_get_ctl,
1614 #endif
1615         .owner          = THIS_MODULE,
1616 };
1617 
1618 static int __net_init arp_tables_net_init(struct net *net)
1619 {
1620         return xt_proto_init(net, NFPROTO_ARP);
1621 }
1622 
1623 static void __net_exit arp_tables_net_exit(struct net *net)
1624 {
1625         xt_proto_fini(net, NFPROTO_ARP);
1626 }
1627 
1628 static struct pernet_operations arp_tables_net_ops = {
1629         .init = arp_tables_net_init,
1630         .exit = arp_tables_net_exit,
1631 };
1632 
1633 static int __init arp_tables_init(void)
1634 {
1635         int ret;
1636 
1637         ret = register_pernet_subsys(&arp_tables_net_ops);
1638         if (ret < 0)
1639                 goto err1;
1640 
1641         /* No one else will be downing sem now, so we won't sleep */
1642         ret = xt_register_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1643         if (ret < 0)
1644                 goto err2;
1645 
1646         /* Register setsockopt */
1647         ret = nf_register_sockopt(&arpt_sockopts);
1648         if (ret < 0)
1649                 goto err4;
1650 
1651         return 0;
1652 
1653 err4:
1654         xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1655 err2:
1656         unregister_pernet_subsys(&arp_tables_net_ops);
1657 err1:
1658         return ret;
1659 }
1660 
1661 static void __exit arp_tables_fini(void)
1662 {
1663         nf_unregister_sockopt(&arpt_sockopts);
1664         xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1665         unregister_pernet_subsys(&arp_tables_net_ops);
1666 }
1667 
1668 EXPORT_SYMBOL(arpt_register_table);
1669 EXPORT_SYMBOL(arpt_unregister_table);
1670 EXPORT_SYMBOL(arpt_do_table);
1671 
1672 module_init(arp_tables_init);
1673 module_exit(arp_tables_fini);
1674 

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