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  * 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 <asm/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 #define FWINV(bool, invflg) ((bool) ^ !!(arpinfo->invflags & (invflg)))
  93
  94         if (FWINV((arphdr->ar_op & arpinfo->arpop_mask) != arpinfo->arpop,
  95                   ARPT_INV_ARPOP))
  96                 return 0;
  97
  98         if (FWINV((arphdr->ar_hrd & arpinfo->arhrd_mask) != arpinfo->arhrd,
  99                   ARPT_INV_ARPHRD))
 100                 return 0;
 101
 102         if (FWINV((arphdr->ar_pro & arpinfo->arpro_mask) != arpinfo->arpro,
 103                   ARPT_INV_ARPPRO))
 104                 return 0;
 105
 106         if (FWINV((arphdr->ar_hln & arpinfo->arhln_mask) != arpinfo->arhln,
 107                   ARPT_INV_ARPHLN))
 108                 return 0;
 109
 110         src_devaddr = arpptr;
 111         arpptr += dev->addr_len;
 112         memcpy(&src_ipaddr, arpptr, sizeof(u32));
 113         arpptr += sizeof(u32);
 114         tgt_devaddr = arpptr;
 115         arpptr += dev->addr_len;
 116         memcpy(&tgt_ipaddr, arpptr, sizeof(u32));
 117
 118         if (FWINV(arp_devaddr_compare(&arpinfo->src_devaddr, src_devaddr, dev->addr_len),
 119                   ARPT_INV_SRCDEVADDR) ||
 120             FWINV(arp_devaddr_compare(&arpinfo->tgt_devaddr, tgt_devaddr, dev->addr_len),
 121                   ARPT_INV_TGTDEVADDR))
 122                 return 0;
 123
 124         if (FWINV((src_ipaddr & arpinfo->smsk.s_addr) != arpinfo->src.s_addr,
 125                   ARPT_INV_SRCIP) ||
 126             FWINV(((tgt_ipaddr & arpinfo->tmsk.s_addr) != arpinfo->tgt.s_addr),
 127                   ARPT_INV_TGTIP))
 128                 return 0;
 129
 130         /* Look for ifname matches.  */
 131         ret = ifname_compare(indev, arpinfo->iniface, arpinfo->iniface_mask);
 132
 133         if (FWINV(ret != 0, ARPT_INV_VIA_IN))
 134                 return 0;
 135
 136         ret = ifname_compare(outdev, arpinfo->outiface, arpinfo->outiface_mask);
 137
 138         if (FWINV(ret != 0, ARPT_INV_VIA_OUT))
 139                 return 0;
 140
 141         return 1;
 142 #undef FWINV
 143 }
 144
 145 static inline int arp_checkentry(const struct arpt_arp *arp)
 146 {
 147         if (arp->flags & ~ARPT_F_MASK)
 148                 return 0;
 149         if (arp->invflags & ~ARPT_INV_MASK)
 150                 return 0;
 151
 152         return 1;
 153 }
 154
 155 static unsigned int
 156 arpt_error(struct sk_buff *skb, const struct xt_action_param *par)
 157 {
 158         net_err_ratelimited("arp_tables: error: '%s'\n",
 159                             (const char *)par->targinfo);
 160
 161         return NF_DROP;
 162 }
 163
 164 static inline const struct xt_entry_target *
 165 arpt_get_target_c(const struct arpt_entry *e)
 166 {
 167         return arpt_get_target((struct arpt_entry *)e);
 168 }
 169
 170 static inline struct arpt_entry *
 171 get_entry(const void *base, unsigned int offset)
 172 {
 173         return (struct arpt_entry *)(base + offset);
 174 }
 175
 176 static inline
 177 struct arpt_entry *arpt_next_entry(const struct arpt_entry *entry)
 178 {
 179         return (void *)entry + entry->next_offset;
 180 }
 181
 182 unsigned int arpt_do_table(struct sk_buff *skb,
 183                            const struct nf_hook_state *state,
 184                            struct xt_table *table)
 185 {
 186         unsigned int hook = state->hook;
 187         static const char nulldevname[IFNAMSIZ] __attribute__((aligned(sizeof(long))));
 188         unsigned int verdict = NF_DROP;
 189         const struct arphdr *arp;
 190         struct arpt_entry *e, **jumpstack;
 191         const char *indev, *outdev;
 192         const void *table_base;
 193         unsigned int cpu, stackidx = 0;
 194         const struct xt_table_info *private;
 195         struct xt_action_param acpar;
 196         unsigned int addend;
 197
 198         if (!pskb_may_pull(skb, arp_hdr_len(skb->dev)))
 199                 return NF_DROP;
 200
 201         indev = state->in ? state->in->name : nulldevname;
 202         outdev = state->out ? state->out->name : nulldevname;
 203
 204         local_bh_disable();
 205         addend = xt_write_recseq_begin();
 206         private = table->private;
 207         cpu     = smp_processor_id();
 208         /*
 209          * Ensure we load private-> members after we've fetched the base
 210          * pointer.
 211          */
 212         smp_read_barrier_depends();
 213         table_base = private->entries;
 214         jumpstack  = (struct arpt_entry **)private->jumpstack[cpu];
 215
 216         /* No TEE support for arptables, so no need to switch to alternate
 217          * stack.  All targets that reenter must return absolute verdicts.
 218          */
 219         e = get_entry(table_base, private->hook_entry[hook]);
 220
 221         acpar.net     = state->net;
 222         acpar.in      = state->in;
 223         acpar.out     = state->out;
 224         acpar.hooknum = hook;
 225         acpar.family  = NFPROTO_ARP;
 226         acpar.hotdrop = false;
 227
 228         arp = arp_hdr(skb);
 229         do {
 230                 const struct xt_entry_target *t;
 231                 struct xt_counters *counter;
 232
 233                 if (!arp_packet_match(arp, skb->dev, indev, outdev, &e->arp)) {
 234                         e = arpt_next_entry(e);
 235                         continue;
 236                 }
 237
 238                 counter = xt_get_this_cpu_counter(&e->counters);
 239                 ADD_COUNTER(*counter, arp_hdr_len(skb->dev), 1);
 240
 241                 t = arpt_get_target_c(e);
 242
 243                 /* Standard target? */
 244                 if (!t->u.kernel.target->target) {
 245                         int v;
 246
 247                         v = ((struct xt_standard_target *)t)->verdict;
 248                         if (v < 0) {
 249                                 /* Pop from stack? */
 250                                 if (v != XT_RETURN) {
 251                                         verdict = (unsigned int)(-v) - 1;
 252                                         break;
 253                                 }
 254                                 if (stackidx == 0) {
 255                                         e = get_entry(table_base,
 256                                                       private->underflow[hook]);
 257                                 } else {
 258                                         e = jumpstack[--stackidx];
 259                                         e = arpt_next_entry(e);
 260                                 }
 261                                 continue;
 262                         }
 263                         if (table_base + v
 264                             != arpt_next_entry(e)) {
 265                                 jumpstack[stackidx++] = e;
 266                         }
 267
 268                         e = get_entry(table_base, v);
 269                         continue;
 270                 }
 271
 272                 acpar.target   = t->u.kernel.target;
 273                 acpar.targinfo = t->data;
 274                 verdict = t->u.kernel.target->target(skb, &acpar);
 275
 276                 /* Target might have changed stuff. */
 277                 arp = arp_hdr(skb);
 278
 279                 if (verdict == XT_CONTINUE)
 280                         e = arpt_next_entry(e);
 281                 else
 282                         /* Verdict */
 283                         break;
 284         } while (!acpar.hotdrop);
 285         xt_write_recseq_end(addend);
 286         local_bh_enable();
 287
 288         if (acpar.hotdrop)
 289                 return NF_DROP;
 290         else
 291                 return verdict;
 292 }
 293
 294 /* All zeroes == unconditional rule. */
 295 static inline bool unconditional(const struct arpt_entry *e)
 296 {
 297         static const struct arpt_arp uncond;
 298
 299         return e->target_offset == sizeof(struct arpt_entry) &&
 300                memcmp(&e->arp, &uncond, sizeof(uncond)) == 0;
 301 }
 302
 303 static bool find_jump_target(const struct xt_table_info *t,
 304                              const struct arpt_entry *target)
 305 {
 306         struct arpt_entry *iter;
 307
 308         xt_entry_foreach(iter, t->entries, t->size) {
 309                  if (iter == target)
 310                         return true;
 311         }
 312         return false;
 313 }
 314
 315 /* Figures out from what hook each rule can be called: returns 0 if
 316  * there are loops.  Puts hook bitmask in comefrom.
 317  */
 318 static int mark_source_chains(const struct xt_table_info *newinfo,
 319                               unsigned int valid_hooks, void *entry0)
 320 {
 321         unsigned int hook;
 322
 323         /* No recursion; use packet counter to save back ptrs (reset
 324          * to 0 as we leave), and comefrom to save source hook bitmask.
 325          */
 326         for (hook = 0; hook < NF_ARP_NUMHOOKS; hook++) {
 327                 unsigned int pos = newinfo->hook_entry[hook];
 328                 struct arpt_entry *e
 329                         = (struct arpt_entry *)(entry0 + pos);
 330
 331                 if (!(valid_hooks & (1 << hook)))
 332                         continue;
 333
 334                 /* Set initial back pointer. */
 335                 e->counters.pcnt = pos;
 336
 337                 for (;;) {
 338                         const struct xt_standard_target *t
 339                                 = (void *)arpt_get_target_c(e);
 340                         int visited = e->comefrom & (1 << hook);
 341
 342                         if (e->comefrom & (1 << NF_ARP_NUMHOOKS))
 343                                 return 0;
 344
 345                         e->comefrom
 346                                 |= ((1 << hook) | (1 << NF_ARP_NUMHOOKS));
 347
 348                         /* Unconditional return/END. */
 349                         if ((unconditional(e) &&
 350                              (strcmp(t->target.u.user.name,
 351                                      XT_STANDARD_TARGET) == 0) &&
 352                              t->verdict < 0) || visited) {
 353                                 unsigned int oldpos, size;
 354
 355                                 if ((strcmp(t->target.u.user.name,
 356                                             XT_STANDARD_TARGET) == 0) &&
 357                                     t->verdict < -NF_MAX_VERDICT - 1)
 358                                         return 0;
 359
 360                                 /* Return: backtrack through the last
 361                                  * big jump.
 362                                  */
 363                                 do {
 364                                         e->comefrom ^= (1<<NF_ARP_NUMHOOKS);
 365                                         oldpos = pos;
 366                                         pos = e->counters.pcnt;
 367                                         e->counters.pcnt = 0;
 368
 369                                         /* We're at the start. */
 370                                         if (pos == oldpos)
 371                                                 goto next;
 372
 373                                         e = (struct arpt_entry *)
 374                                                 (entry0 + pos);
 375                                 } while (oldpos == pos + e->next_offset);
 376
 377                                 /* Move along one */
 378                                 size = e->next_offset;
 379                                 e = (struct arpt_entry *)
 380                                         (entry0 + pos + size);
 381                                 if (pos + size >= newinfo->size)
 382                                         return 0;
 383                                 e->counters.pcnt = pos;
 384                                 pos += size;
 385                         } else {
 386                                 int newpos = t->verdict;
 387
 388                                 if (strcmp(t->target.u.user.name,
 389                                            XT_STANDARD_TARGET) == 0 &&
 390                                     newpos >= 0) {
 391                                         /* This a jump; chase it. */
 392                                         e = (struct arpt_entry *)
 393                                                 (entry0 + newpos);
 394                                         if (!find_jump_target(newinfo, e))
 395                                                 return 0;
 396                                 } else {
 397                                         /* ... this is a fallthru */
 398                                         newpos = pos + e->next_offset;
 399                                         if (newpos >= newinfo->size)
 400                                                 return 0;
 401                                 }
 402                                 e = (struct arpt_entry *)
 403                                         (entry0 + newpos);
 404                                 e->counters.pcnt = pos;
 405                                 pos = newpos;
 406                         }
 407                 }
 408 next:           ;
 409         }
 410         return 1;
 411 }
 412
 413 static inline int check_target(struct arpt_entry *e, const char *name)
 414 {
 415         struct xt_entry_target *t = arpt_get_target(e);
 416         struct xt_tgchk_param par = {
 417                 .table     = name,
 418                 .entryinfo = e,
 419                 .target    = t->u.kernel.target,
 420                 .targinfo  = t->data,
 421                 .hook_mask = e->comefrom,
 422                 .family    = NFPROTO_ARP,
 423         };
 424
 425         return xt_check_target(&par, t->u.target_size - sizeof(*t), 0, false);
 426 }
 427
 428 static inline int
 429 find_check_entry(struct arpt_entry *e, const char *name, unsigned int size)
 430 {
 431         struct xt_entry_target *t;
 432         struct xt_target *target;
 433         unsigned long pcnt;
 434         int ret;
 435
 436         pcnt = xt_percpu_counter_alloc();
 437         if (IS_ERR_VALUE(pcnt))
 438                 return -ENOMEM;
 439         e->counters.pcnt = pcnt;
 440
 441         t = arpt_get_target(e);
 442         target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
 443                                         t->u.user.revision);
 444         if (IS_ERR(target)) {
 445                 ret = PTR_ERR(target);
 446                 goto out;
 447         }
 448         t->u.kernel.target = target;
 449
 450         ret = check_target(e, name);
 451         if (ret)
 452                 goto err;
 453         return 0;
 454 err:
 455         module_put(t->u.kernel.target->me);
 456 out:
 457         xt_percpu_counter_free(e->counters.pcnt);
 458
 459         return ret;
 460 }
 461
 462 static bool check_underflow(const struct arpt_entry *e)
 463 {
 464         const struct xt_entry_target *t;
 465         unsigned int verdict;
 466
 467         if (!unconditional(e))
 468                 return false;
 469         t = arpt_get_target_c(e);
 470         if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
 471                 return false;
 472         verdict = ((struct xt_standard_target *)t)->verdict;
 473         verdict = -verdict - 1;
 474         return verdict == NF_DROP || verdict == NF_ACCEPT;
 475 }
 476
 477 static inline int check_entry_size_and_hooks(struct arpt_entry *e,
 478                                              struct xt_table_info *newinfo,
 479                                              const unsigned char *base,
 480                                              const unsigned char *limit,
 481                                              const unsigned int *hook_entries,
 482                                              const unsigned int *underflows,
 483                                              unsigned int valid_hooks)
 484 {
 485         unsigned int h;
 486         int err;
 487
 488         if ((unsigned long)e % __alignof__(struct arpt_entry) != 0 ||
 489             (unsigned char *)e + sizeof(struct arpt_entry) >= limit ||
 490             (unsigned char *)e + e->next_offset > limit)
 491                 return -EINVAL;
 492
 493         if (e->next_offset
 494             < sizeof(struct arpt_entry) + sizeof(struct xt_entry_target))
 495                 return -EINVAL;
 496
 497         if (!arp_checkentry(&e->arp))
 498                 return -EINVAL;
 499
 500         err = xt_check_entry_offsets(e, e->elems, e->target_offset,
 501                                      e->next_offset);
 502         if (err)
 503                 return err;
 504
 505         /* Check hooks & underflows */
 506         for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
 507                 if (!(valid_hooks & (1 << h)))
 508                         continue;
 509                 if ((unsigned char *)e - base == hook_entries[h])
 510                         newinfo->hook_entry[h] = hook_entries[h];
 511                 if ((unsigned char *)e - base == underflows[h]) {
 512                         if (!check_underflow(e))
 513                                 return -EINVAL;
 514
 515                         newinfo->underflow[h] = underflows[h];
 516                 }
 517         }
 518
 519         /* Clear counters and comefrom */
 520         e->counters = ((struct xt_counters) { 0, 0 });
 521         e->comefrom = 0;
 522         return 0;
 523 }
 524
 525 static inline void cleanup_entry(struct arpt_entry *e)
 526 {
 527         struct xt_tgdtor_param par;
 528         struct xt_entry_target *t;
 529
 530         t = arpt_get_target(e);
 531         par.target   = t->u.kernel.target;
 532         par.targinfo = t->data;
 533         par.family   = NFPROTO_ARP;
 534         if (par.target->destroy != NULL)
 535                 par.target->destroy(&par);
 536         module_put(par.target->me);
 537         xt_percpu_counter_free(e->counters.pcnt);
 538 }
 539
 540 /* Checks and translates the user-supplied table segment (held in
 541  * newinfo).
 542  */
 543 static int translate_table(struct xt_table_info *newinfo, void *entry0,
 544                            const struct arpt_replace *repl)
 545 {
 546         struct arpt_entry *iter;
 547         unsigned int i;
 548         int ret = 0;
 549
 550         newinfo->size = repl->size;
 551         newinfo->number = repl->num_entries;
 552
 553         /* Init all hooks to impossible value. */
 554         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
 555                 newinfo->hook_entry[i] = 0xFFFFFFFF;
 556                 newinfo->underflow[i] = 0xFFFFFFFF;
 557         }
 558
 559         i = 0;
 560
 561         /* Walk through entries, checking offsets. */
 562         xt_entry_foreach(iter, entry0, newinfo->size) {
 563                 ret = check_entry_size_and_hooks(iter, newinfo, entry0,
 564                                                  entry0 + repl->size,
 565                                                  repl->hook_entry,
 566                                                  repl->underflow,
 567                                                  repl->valid_hooks);
 568                 if (ret != 0)
 569                         break;
 570                 ++i;
 571                 if (strcmp(arpt_get_target(iter)->u.user.name,
 572                     XT_ERROR_TARGET) == 0)
 573                         ++newinfo->stacksize;
 574         }
 575         if (ret != 0)
 576                 return ret;
 577
 578         if (i != repl->num_entries)
 579                 return -EINVAL;
 580
 581         /* Check hooks all assigned */
 582         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
 583                 /* Only hooks which are valid */
 584                 if (!(repl->valid_hooks & (1 << i)))
 585                         continue;
 586                 if (newinfo->hook_entry[i] == 0xFFFFFFFF)
 587                         return -EINVAL;
 588                 if (newinfo->underflow[i] == 0xFFFFFFFF)
 589                         return -EINVAL;
 590         }
 591
 592         if (!mark_source_chains(newinfo, repl->valid_hooks, entry0))
 593                 return -ELOOP;
 594
 595         /* Finally, each sanity check must pass */
 596         i = 0;
 597         xt_entry_foreach(iter, entry0, newinfo->size) {
 598                 ret = find_check_entry(iter, repl->name, repl->size);
 599                 if (ret != 0)
 600                         break;
 601                 ++i;
 602         }
 603
 604         if (ret != 0) {
 605                 xt_entry_foreach(iter, entry0, newinfo->size) {
 606                         if (i-- == 0)
 607                                 break;
 608                         cleanup_entry(iter);
 609                 }
 610                 return ret;
 611         }
 612
 613         return ret;
 614 }
 615
 616 static void get_counters(const struct xt_table_info *t,
 617                          struct xt_counters counters[])
 618 {
 619         struct arpt_entry *iter;
 620         unsigned int cpu;
 621         unsigned int i;
 622
 623         for_each_possible_cpu(cpu) {
 624                 seqcount_t *s = &per_cpu(xt_recseq, cpu);
 625
 626                 i = 0;
 627                 xt_entry_foreach(iter, t->entries, t->size) {
 628                         struct xt_counters *tmp;
 629                         u64 bcnt, pcnt;
 630                         unsigned int start;
 631
 632                         tmp = xt_get_per_cpu_counter(&iter->counters, cpu);
 633                         do {
 634                                 start = read_seqcount_begin(s);
 635                                 bcnt = tmp->bcnt;
 636                                 pcnt = tmp->pcnt;
 637                         } while (read_seqcount_retry(s, start));
 638
 639                         ADD_COUNTER(counters[i], bcnt, pcnt);
 640                         ++i;
 641                 }
 642         }
 643 }
 644
 645 static struct xt_counters *alloc_counters(const struct xt_table *table)
 646 {
 647         unsigned int countersize;
 648         struct xt_counters *counters;
 649         const struct xt_table_info *private = table->private;
 650
 651         /* We need atomic snapshot of counters: rest doesn't change
 652          * (other than comefrom, which userspace doesn't care
 653          * about).
 654          */
 655         countersize = sizeof(struct xt_counters) * private->number;
 656         counters = vzalloc(countersize);
 657
 658         if (counters == NULL)
 659                 return ERR_PTR(-ENOMEM);
 660
 661         get_counters(private, counters);
 662
 663         return counters;
 664 }
 665
 666 static int copy_entries_to_user(unsigned int total_size,
 667                                 const struct xt_table *table,
 668                                 void __user *userptr)
 669 {
 670         unsigned int off, num;
 671         const struct arpt_entry *e;
 672         struct xt_counters *counters;
 673         struct xt_table_info *private = table->private;
 674         int ret = 0;
 675         void *loc_cpu_entry;
 676
 677         counters = alloc_counters(table);
 678         if (IS_ERR(counters))
 679                 return PTR_ERR(counters);
 680
 681         loc_cpu_entry = private->entries;
 682         /* ... then copy entire thing ... */
 683         if (copy_to_user(userptr, loc_cpu_entry, total_size) != 0) {
 684                 ret = -EFAULT;
 685                 goto free_counters;
 686         }
 687
 688         /* FIXME: use iterator macros --RR */
 689         /* ... then go back and fix counters and names */
 690         for (off = 0, num = 0; off < total_size; off += e->next_offset, num++){
 691                 const struct xt_entry_target *t;
 692
 693                 e = (struct arpt_entry *)(loc_cpu_entry + off);
 694                 if (copy_to_user(userptr + off
 695                                  + offsetof(struct arpt_entry, counters),
 696                                  &counters[num],
 697                                  sizeof(counters[num])) != 0) {
 698                         ret = -EFAULT;
 699                         goto free_counters;
 700                 }
 701
 702                 t = arpt_get_target_c(e);
 703                 if (copy_to_user(userptr + off + e->target_offset
 704                                  + offsetof(struct xt_entry_target,
 705                                             u.user.name),
 706                                  t->u.kernel.target->name,
 707                                  strlen(t->u.kernel.target->name)+1) != 0) {
 708                         ret = -EFAULT;
 709                         goto free_counters;
 710                 }
 711         }
 712
 713  free_counters:
 714         vfree(counters);
 715         return ret;
 716 }
 717
 718 #ifdef CONFIG_COMPAT
 719 static void compat_standard_from_user(void *dst, const void *src)
 720 {
 721         int v = *(compat_int_t *)src;
 722
 723         if (v > 0)
 724                 v += xt_compat_calc_jump(NFPROTO_ARP, v);
 725         memcpy(dst, &v, sizeof(v));
 726 }
 727
 728 static int compat_standard_to_user(void __user *dst, const void *src)
 729 {
 730         compat_int_t cv = *(int *)src;
 731
 732         if (cv > 0)
 733                 cv -= xt_compat_calc_jump(NFPROTO_ARP, cv);
 734         return copy_to_user(dst, &cv, sizeof(cv)) ? -EFAULT : 0;
 735 }
 736
 737 static int compat_calc_entry(const struct arpt_entry *e,
 738                              const struct xt_table_info *info,
 739                              const void *base, struct xt_table_info *newinfo)
 740 {
 741         const struct xt_entry_target *t;
 742         unsigned int entry_offset;
 743         int off, i, ret;
 744
 745         off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
 746         entry_offset = (void *)e - base;
 747
 748         t = arpt_get_target_c(e);
 749         off += xt_compat_target_offset(t->u.kernel.target);
 750         newinfo->size -= off;
 751         ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
 752         if (ret)
 753                 return ret;
 754
 755         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
 756                 if (info->hook_entry[i] &&
 757                     (e < (struct arpt_entry *)(base + info->hook_entry[i])))
 758                         newinfo->hook_entry[i] -= off;
 759                 if (info->underflow[i] &&
 760                     (e < (struct arpt_entry *)(base + info->underflow[i])))
 761                         newinfo->underflow[i] -= off;
 762         }
 763         return 0;
 764 }
 765
 766 static int compat_table_info(const struct xt_table_info *info,
 767                              struct xt_table_info *newinfo)
 768 {
 769         struct arpt_entry *iter;
 770         const void *loc_cpu_entry;
 771         int ret;
 772
 773         if (!newinfo || !info)
 774                 return -EINVAL;
 775
 776         /* we dont care about newinfo->entries */
 777         memcpy(newinfo, info, offsetof(struct xt_table_info, entries));
 778         newinfo->initial_entries = 0;
 779         loc_cpu_entry = info->entries;
 780         xt_compat_init_offsets(NFPROTO_ARP, info->number);
 781         xt_entry_foreach(iter, loc_cpu_entry, info->size) {
 782                 ret = compat_calc_entry(iter, info, loc_cpu_entry, newinfo);
 783                 if (ret != 0)
 784                         return ret;
 785         }
 786         return 0;
 787 }
 788 #endif
 789
 790 static int get_info(struct net *net, void __user *user,
 791                     const int *len, int compat)
 792 {
 793         char name[XT_TABLE_MAXNAMELEN];
 794         struct xt_table *t;
 795         int ret;
 796
 797         if (*len != sizeof(struct arpt_getinfo))
 798                 return -EINVAL;
 799
 800         if (copy_from_user(name, user, sizeof(name)) != 0)
 801                 return -EFAULT;
 802
 803         name[XT_TABLE_MAXNAMELEN-1] = '\0';
 804 #ifdef CONFIG_COMPAT
 805         if (compat)
 806                 xt_compat_lock(NFPROTO_ARP);
 807 #endif
 808         t = try_then_request_module(xt_find_table_lock(net, NFPROTO_ARP, name),
 809                                     "arptable_%s", name);
 810         if (!IS_ERR_OR_NULL(t)) {
 811                 struct arpt_getinfo info;
 812                 const struct xt_table_info *private = t->private;
 813 #ifdef CONFIG_COMPAT
 814                 struct xt_table_info tmp;
 815
 816                 if (compat) {
 817                         ret = compat_table_info(private, &tmp);
 818                         xt_compat_flush_offsets(NFPROTO_ARP);
 819                         private = &tmp;
 820                 }
 821 #endif
 822                 memset(&info, 0, sizeof(info));
 823                 info.valid_hooks = t->valid_hooks;
 824                 memcpy(info.hook_entry, private->hook_entry,
 825                        sizeof(info.hook_entry));
 826                 memcpy(info.underflow, private->underflow,
 827                        sizeof(info.underflow));
 828                 info.num_entries = private->number;
 829                 info.size = private->size;
 830                 strcpy(info.name, name);
 831
 832                 if (copy_to_user(user, &info, *len) != 0)
 833                         ret = -EFAULT;
 834                 else
 835                         ret = 0;
 836                 xt_table_unlock(t);
 837                 module_put(t->me);
 838         } else
 839                 ret = t ? PTR_ERR(t) : -ENOENT;
 840 #ifdef CONFIG_COMPAT
 841         if (compat)
 842                 xt_compat_unlock(NFPROTO_ARP);
 843 #endif
 844         return ret;
 845 }
 846
 847 static int get_entries(struct net *net, struct arpt_get_entries __user *uptr,
 848                        const int *len)
 849 {
 850         int ret;
 851         struct arpt_get_entries get;
 852         struct xt_table *t;
 853
 854         if (*len < sizeof(get))
 855                 return -EINVAL;
 856         if (copy_from_user(&get, uptr, sizeof(get)) != 0)
 857                 return -EFAULT;
 858         if (*len != sizeof(struct arpt_get_entries) + get.size)
 859                 return -EINVAL;
 860
 861         get.name[sizeof(get.name) - 1] = '\0';
 862
 863         t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
 864         if (!IS_ERR_OR_NULL(t)) {
 865                 const struct xt_table_info *private = t->private;
 866
 867                 if (get.size == private->size)
 868                         ret = copy_entries_to_user(private->size,
 869                                                    t, uptr->entrytable);
 870                 else
 871                         ret = -EAGAIN;
 872
 873                 module_put(t->me);
 874                 xt_table_unlock(t);
 875         } else
 876                 ret = t ? PTR_ERR(t) : -ENOENT;
 877
 878         return ret;
 879 }
 880
 881 static int __do_replace(struct net *net, const char *name,
 882                         unsigned int valid_hooks,
 883                         struct xt_table_info *newinfo,
 884                         unsigned int num_counters,
 885                         void __user *counters_ptr)
 886 {
 887         int ret;
 888         struct xt_table *t;
 889         struct xt_table_info *oldinfo;
 890         struct xt_counters *counters;
 891         void *loc_cpu_old_entry;
 892         struct arpt_entry *iter;
 893
 894         ret = 0;
 895         counters = vzalloc(num_counters * sizeof(struct xt_counters));
 896         if (!counters) {
 897                 ret = -ENOMEM;
 898                 goto out;
 899         }
 900
 901         t = try_then_request_module(xt_find_table_lock(net, NFPROTO_ARP, name),
 902                                     "arptable_%s", name);
 903         if (IS_ERR_OR_NULL(t)) {
 904                 ret = t ? PTR_ERR(t) : -ENOENT;
 905                 goto free_newinfo_counters_untrans;
 906         }
 907
 908         /* You lied! */
 909         if (valid_hooks != t->valid_hooks) {
 910                 ret = -EINVAL;
 911                 goto put_module;
 912         }
 913
 914         oldinfo = xt_replace_table(t, num_counters, newinfo, &ret);
 915         if (!oldinfo)
 916                 goto put_module;
 917
 918         /* Update module usage count based on number of rules */
 919         if ((oldinfo->number > oldinfo->initial_entries) ||
 920             (newinfo->number <= oldinfo->initial_entries))
 921                 module_put(t->me);
 922         if ((oldinfo->number > oldinfo->initial_entries) &&
 923             (newinfo->number <= oldinfo->initial_entries))
 924                 module_put(t->me);
 925
 926         /* Get the old counters, and synchronize with replace */
 927         get_counters(oldinfo, counters);
 928
 929         /* Decrease module usage counts and free resource */
 930         loc_cpu_old_entry = oldinfo->entries;
 931         xt_entry_foreach(iter, loc_cpu_old_entry, oldinfo->size)
 932                 cleanup_entry(iter);
 933
 934         xt_free_table_info(oldinfo);
 935         if (copy_to_user(counters_ptr, counters,
 936                          sizeof(struct xt_counters) * num_counters) != 0) {
 937                 /* Silent error, can't fail, new table is already in place */
 938                 net_warn_ratelimited("arptables: counters copy to user failed while replacing table\n");
 939         }
 940         vfree(counters);
 941         xt_table_unlock(t);
 942         return ret;
 943
 944  put_module:
 945         module_put(t->me);
 946         xt_table_unlock(t);
 947  free_newinfo_counters_untrans:
 948         vfree(counters);
 949  out:
 950         return ret;
 951 }
 952
 953 static int do_replace(struct net *net, const void __user *user,
 954                       unsigned int len)
 955 {
 956         int ret;
 957         struct arpt_replace tmp;
 958         struct xt_table_info *newinfo;
 959         void *loc_cpu_entry;
 960         struct arpt_entry *iter;
 961
 962         if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
 963                 return -EFAULT;
 964
 965         /* overflow check */
 966         if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
 967                 return -ENOMEM;
 968         if (tmp.num_counters == 0)
 969                 return -EINVAL;
 970
 971         tmp.name[sizeof(tmp.name)-1] = 0;
 972
 973         newinfo = xt_alloc_table_info(tmp.size);
 974         if (!newinfo)
 975                 return -ENOMEM;
 976
 977         loc_cpu_entry = newinfo->entries;
 978         if (copy_from_user(loc_cpu_entry, user + sizeof(tmp),
 979                            tmp.size) != 0) {
 980                 ret = -EFAULT;
 981                 goto free_newinfo;
 982         }
 983
 984         ret = translate_table(newinfo, loc_cpu_entry, &tmp);
 985         if (ret != 0)
 986                 goto free_newinfo;
 987
 988         ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
 989                            tmp.num_counters, tmp.counters);
 990         if (ret)
 991                 goto free_newinfo_untrans;
 992         return 0;
 993
 994  free_newinfo_untrans:
 995         xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
 996                 cleanup_entry(iter);
 997  free_newinfo:
 998         xt_free_table_info(newinfo);
 999         return ret;
1000 }
1001
1002 static int do_add_counters(struct net *net, const void __user *user,
1003                            unsigned int len, int compat)
1004 {
1005         unsigned int i;
1006         struct xt_counters_info tmp;
1007         struct xt_counters *paddc;
1008         struct xt_table *t;
1009         const struct xt_table_info *private;
1010         int ret = 0;
1011         struct arpt_entry *iter;
1012         unsigned int addend;
1013
1014         paddc = xt_copy_counters_from_user(user, len, &tmp, compat);
1015         if (IS_ERR(paddc))
1016                 return PTR_ERR(paddc);
1017
1018         t = xt_find_table_lock(net, NFPROTO_ARP, tmp.name);
1019         if (IS_ERR_OR_NULL(t)) {
1020                 ret = t ? PTR_ERR(t) : -ENOENT;
1021                 goto free;
1022         }
1023
1024         local_bh_disable();
1025         private = t->private;
1026         if (private->number != tmp.num_counters) {
1027                 ret = -EINVAL;
1028                 goto unlock_up_free;
1029         }
1030
1031         i = 0;
1032
1033         addend = xt_write_recseq_begin();
1034         xt_entry_foreach(iter,  private->entries, private->size) {
1035                 struct xt_counters *tmp;
1036
1037                 tmp = xt_get_this_cpu_counter(&iter->counters);
1038                 ADD_COUNTER(*tmp, paddc[i].bcnt, paddc[i].pcnt);
1039                 ++i;
1040         }
1041         xt_write_recseq_end(addend);
1042  unlock_up_free:
1043         local_bh_enable();
1044         xt_table_unlock(t);
1045         module_put(t->me);
1046  free:
1047         vfree(paddc);
1048
1049         return ret;
1050 }
1051
1052 #ifdef CONFIG_COMPAT
1053 struct compat_arpt_replace {
1054         char                            name[XT_TABLE_MAXNAMELEN];
1055         u32                             valid_hooks;
1056         u32                             num_entries;
1057         u32                             size;
1058         u32                             hook_entry[NF_ARP_NUMHOOKS];
1059         u32                             underflow[NF_ARP_NUMHOOKS];
1060         u32                             num_counters;
1061         compat_uptr_t                   counters;
1062         struct compat_arpt_entry        entries[0];
1063 };
1064
1065 static inline void compat_release_entry(struct compat_arpt_entry *e)
1066 {
1067         struct xt_entry_target *t;
1068
1069         t = compat_arpt_get_target(e);
1070         module_put(t->u.kernel.target->me);
1071 }
1072
1073 static int
1074 check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
1075                                   struct xt_table_info *newinfo,
1076                                   unsigned int *size,
1077                                   const unsigned char *base,
1078                                   const unsigned char *limit)
1079 {
1080         struct xt_entry_target *t;
1081         struct xt_target *target;
1082         unsigned int entry_offset;
1083         int ret, off;
1084
1085         if ((unsigned long)e % __alignof__(struct compat_arpt_entry) != 0 ||
1086             (unsigned char *)e + sizeof(struct compat_arpt_entry) >= limit ||
1087             (unsigned char *)e + e->next_offset > limit)
1088                 return -EINVAL;
1089
1090         if (e->next_offset < sizeof(struct compat_arpt_entry) +
1091                              sizeof(struct compat_xt_entry_target))
1092                 return -EINVAL;
1093
1094         if (!arp_checkentry(&e->arp))
1095                 return -EINVAL;
1096
1097         ret = xt_compat_check_entry_offsets(e, e->elems, e->target_offset,
1098                                             e->next_offset);
1099         if (ret)
1100                 return ret;
1101
1102         off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1103         entry_offset = (void *)e - (void *)base;
1104
1105         t = compat_arpt_get_target(e);
1106         target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
1107                                         t->u.user.revision);
1108         if (IS_ERR(target)) {
1109                 ret = PTR_ERR(target);
1110                 goto out;
1111         }
1112         t->u.kernel.target = target;
1113
1114         off += xt_compat_target_offset(target);
1115         *size += off;
1116         ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
1117         if (ret)
1118                 goto release_target;
1119
1120         return 0;
1121
1122 release_target:
1123         module_put(t->u.kernel.target->me);
1124 out:
1125         return ret;
1126 }
1127
1128 static void
1129 compat_copy_entry_from_user(struct compat_arpt_entry *e, void **dstptr,
1130                             unsigned int *size,
1131                             struct xt_table_info *newinfo, unsigned char *base)
1132 {
1133         struct xt_entry_target *t;
1134         struct xt_target *target;
1135         struct arpt_entry *de;
1136         unsigned int origsize;
1137         int h;
1138
1139         origsize = *size;
1140         de = (struct arpt_entry *)*dstptr;
1141         memcpy(de, e, sizeof(struct arpt_entry));
1142         memcpy(&de->counters, &e->counters, sizeof(e->counters));
1143
1144         *dstptr += sizeof(struct arpt_entry);
1145         *size += sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1146
1147         de->target_offset = e->target_offset - (origsize - *size);
1148         t = compat_arpt_get_target(e);
1149         target = t->u.kernel.target;
1150         xt_compat_target_from_user(t, dstptr, size);
1151
1152         de->next_offset = e->next_offset - (origsize - *size);
1153         for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
1154                 if ((unsigned char *)de - base < newinfo->hook_entry[h])
1155                         newinfo->hook_entry[h] -= origsize - *size;
1156                 if ((unsigned char *)de - base < newinfo->underflow[h])
1157                         newinfo->underflow[h] -= origsize - *size;
1158         }
1159 }
1160
1161 static int translate_compat_table(struct xt_table_info **pinfo,
1162                                   void **pentry0,
1163                                   const struct compat_arpt_replace *compatr)
1164 {
1165         unsigned int i, j;
1166         struct xt_table_info *newinfo, *info;
1167         void *pos, *entry0, *entry1;
1168         struct compat_arpt_entry *iter0;
1169         struct arpt_replace repl;
1170         unsigned int size;
1171         int ret = 0;
1172
1173         info = *pinfo;
1174         entry0 = *pentry0;
1175         size = compatr->size;
1176         info->number = compatr->num_entries;
1177
1178         j = 0;
1179         xt_compat_lock(NFPROTO_ARP);
1180         xt_compat_init_offsets(NFPROTO_ARP, compatr->num_entries);
1181         /* Walk through entries, checking offsets. */
1182         xt_entry_foreach(iter0, entry0, compatr->size) {
1183                 ret = check_compat_entry_size_and_hooks(iter0, info, &size,
1184                                                         entry0,
1185                                                         entry0 + compatr->size);
1186                 if (ret != 0)
1187                         goto out_unlock;
1188                 ++j;
1189         }
1190
1191         ret = -EINVAL;
1192         if (j != compatr->num_entries)
1193                 goto out_unlock;
1194
1195         ret = -ENOMEM;
1196         newinfo = xt_alloc_table_info(size);
1197         if (!newinfo)
1198                 goto out_unlock;
1199
1200         newinfo->number = compatr->num_entries;
1201         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1202                 newinfo->hook_entry[i] = info->hook_entry[i];
1203                 newinfo->underflow[i] = info->underflow[i];
1204         }
1205         entry1 = newinfo->entries;
1206         pos = entry1;
1207         size = compatr->size;
1208         xt_entry_foreach(iter0, entry0, compatr->size)
1209                 compat_copy_entry_from_user(iter0, &pos, &size,
1210                                             newinfo, entry1);
1211
1212         /* all module references in entry0 are now gone */
1213
1214         xt_compat_flush_offsets(NFPROTO_ARP);
1215         xt_compat_unlock(NFPROTO_ARP);
1216
1217         memcpy(&repl, compatr, sizeof(*compatr));
1218
1219         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1220                 repl.hook_entry[i] = newinfo->hook_entry[i];
1221                 repl.underflow[i] = newinfo->underflow[i];
1222         }
1223
1224         repl.num_counters = 0;
1225         repl.counters = NULL;
1226         repl.size = newinfo->size;
1227         ret = translate_table(newinfo, entry1, &repl);
1228         if (ret)
1229                 goto free_newinfo;
1230
1231         *pinfo = newinfo;
1232         *pentry0 = entry1;
1233         xt_free_table_info(info);
1234         return 0;
1235
1236 free_newinfo:
1237         xt_free_table_info(newinfo);
1238         return ret;
1239 out_unlock:
1240         xt_compat_flush_offsets(NFPROTO_ARP);
1241         xt_compat_unlock(NFPROTO_ARP);
1242         xt_entry_foreach(iter0, entry0, compatr->size) {
1243                 if (j-- == 0)
1244                         break;
1245                 compat_release_entry(iter0);
1246         }
1247         return ret;
1248 }
1249
1250 static int compat_do_replace(struct net *net, void __user *user,
1251                              unsigned int len)
1252 {
1253         int ret;
1254         struct compat_arpt_replace tmp;
1255         struct xt_table_info *newinfo;
1256         void *loc_cpu_entry;
1257         struct arpt_entry *iter;
1258
1259         if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
1260                 return -EFAULT;
1261
1262         /* overflow check */
1263         if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
1264                 return -ENOMEM;
1265         if (tmp.num_counters == 0)
1266                 return -EINVAL;
1267
1268         tmp.name[sizeof(tmp.name)-1] = 0;
1269
1270         newinfo = xt_alloc_table_info(tmp.size);
1271         if (!newinfo)
1272                 return -ENOMEM;
1273
1274         loc_cpu_entry = newinfo->entries;
1275         if (copy_from_user(loc_cpu_entry, user + sizeof(tmp), tmp.size) != 0) {
1276                 ret = -EFAULT;
1277                 goto free_newinfo;
1278         }
1279
1280         ret = translate_compat_table(&newinfo, &loc_cpu_entry, &tmp);
1281         if (ret != 0)
1282                 goto free_newinfo;
1283
1284         ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
1285                            tmp.num_counters, compat_ptr(tmp.counters));
1286         if (ret)
1287                 goto free_newinfo_untrans;
1288         return 0;
1289
1290  free_newinfo_untrans:
1291         xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
1292                 cleanup_entry(iter);
1293  free_newinfo:
1294         xt_free_table_info(newinfo);
1295         return ret;
1296 }
1297
1298 static int compat_do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user,
1299                                   unsigned int len)
1300 {
1301         int ret;
1302
1303         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1304                 return -EPERM;
1305
1306         switch (cmd) {
1307         case ARPT_SO_SET_REPLACE:
1308                 ret = compat_do_replace(sock_net(sk), user, len);
1309                 break;
1310
1311         case ARPT_SO_SET_ADD_COUNTERS:
1312                 ret = do_add_counters(sock_net(sk), user, len, 1);
1313                 break;
1314
1315         default:
1316                 ret = -EINVAL;
1317         }
1318
1319         return ret;
1320 }
1321
1322 static int compat_copy_entry_to_user(struct arpt_entry *e, void __user **dstptr,
1323                                      compat_uint_t *size,
1324                                      struct xt_counters *counters,
1325                                      unsigned int i)
1326 {
1327         struct xt_entry_target *t;
1328         struct compat_arpt_entry __user *ce;
1329         u_int16_t target_offset, next_offset;
1330         compat_uint_t origsize;
1331         int ret;
1332
1333         origsize = *size;
1334         ce = (struct compat_arpt_entry __user *)*dstptr;
1335         if (copy_to_user(ce, e, sizeof(struct arpt_entry)) != 0 ||
1336             copy_to_user(&ce->counters, &counters[i],
1337             sizeof(counters[i])) != 0)
1338                 return -EFAULT;
1339
1340         *dstptr += sizeof(struct compat_arpt_entry);
1341         *size -= sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1342
1343         target_offset = e->target_offset - (origsize - *size);
1344
1345         t = arpt_get_target(e);
1346         ret = xt_compat_target_to_user(t, dstptr, size);
1347         if (ret)
1348                 return ret;
1349         next_offset = e->next_offset - (origsize - *size);
1350         if (put_user(target_offset, &ce->target_offset) != 0 ||
1351             put_user(next_offset, &ce->next_offset) != 0)
1352                 return -EFAULT;
1353         return 0;
1354 }
1355
1356 static int compat_copy_entries_to_user(unsigned int total_size,
1357                                        struct xt_table *table,
1358                                        void __user *userptr)
1359 {
1360         struct xt_counters *counters;
1361         const struct xt_table_info *private = table->private;
1362         void __user *pos;
1363         unsigned int size;
1364         int ret = 0;
1365         unsigned int i = 0;
1366         struct arpt_entry *iter;
1367
1368         counters = alloc_counters(table);
1369         if (IS_ERR(counters))
1370                 return PTR_ERR(counters);
1371
1372         pos = userptr;
1373         size = total_size;
1374         xt_entry_foreach(iter, private->entries, total_size) {
1375                 ret = compat_copy_entry_to_user(iter, &pos,
1376                                                 &size, counters, i++);
1377                 if (ret != 0)
1378                         break;
1379         }
1380         vfree(counters);
1381         return ret;
1382 }
1383
1384 struct compat_arpt_get_entries {
1385         char name[XT_TABLE_MAXNAMELEN];
1386         compat_uint_t size;
1387         struct compat_arpt_entry entrytable[0];
1388 };
1389
1390 static int compat_get_entries(struct net *net,
1391                               struct compat_arpt_get_entries __user *uptr,
1392                               int *len)
1393 {
1394         int ret;
1395         struct compat_arpt_get_entries get;
1396         struct xt_table *t;
1397
1398         if (*len < sizeof(get))
1399                 return -EINVAL;
1400         if (copy_from_user(&get, uptr, sizeof(get)) != 0)
1401                 return -EFAULT;
1402         if (*len != sizeof(struct compat_arpt_get_entries) + get.size)
1403                 return -EINVAL;
1404
1405         get.name[sizeof(get.name) - 1] = '\0';
1406
1407         xt_compat_lock(NFPROTO_ARP);
1408         t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
1409         if (!IS_ERR_OR_NULL(t)) {
1410                 const struct xt_table_info *private = t->private;
1411                 struct xt_table_info info;
1412
1413                 ret = compat_table_info(private, &info);
1414                 if (!ret && get.size == info.size) {
1415                         ret = compat_copy_entries_to_user(private->size,
1416                                                           t, uptr->entrytable);
1417                 } else if (!ret)
1418                         ret = -EAGAIN;
1419
1420                 xt_compat_flush_offsets(NFPROTO_ARP);
1421                 module_put(t->me);
1422                 xt_table_unlock(t);
1423         } else
1424                 ret = t ? PTR_ERR(t) : -ENOENT;
1425
1426         xt_compat_unlock(NFPROTO_ARP);
1427         return ret;
1428 }
1429
1430 static int do_arpt_get_ctl(struct sock *, int, void __user *, int *);
1431
1432 static int compat_do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user,
1433                                   int *len)
1434 {
1435         int ret;
1436
1437         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1438                 return -EPERM;
1439
1440         switch (cmd) {
1441         case ARPT_SO_GET_INFO:
1442                 ret = get_info(sock_net(sk), user, len, 1);
1443                 break;
1444         case ARPT_SO_GET_ENTRIES:
1445                 ret = compat_get_entries(sock_net(sk), user, len);
1446                 break;
1447         default:
1448                 ret = do_arpt_get_ctl(sk, cmd, user, len);
1449         }
1450         return ret;
1451 }
1452 #endif
1453
1454 static int do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
1455 {
1456         int ret;
1457
1458         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1459                 return -EPERM;
1460
1461         switch (cmd) {
1462         case ARPT_SO_SET_REPLACE:
1463                 ret = do_replace(sock_net(sk), user, len);
1464                 break;
1465
1466         case ARPT_SO_SET_ADD_COUNTERS:
1467                 ret = do_add_counters(sock_net(sk), user, len, 0);
1468                 break;
1469
1470         default:
1471                 ret = -EINVAL;
1472         }
1473
1474         return ret;
1475 }
1476
1477 static int do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
1478 {
1479         int ret;
1480
1481         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1482                 return -EPERM;
1483
1484         switch (cmd) {
1485         case ARPT_SO_GET_INFO:
1486                 ret = get_info(sock_net(sk), user, len, 0);
1487                 break;
1488
1489         case ARPT_SO_GET_ENTRIES:
1490                 ret = get_entries(sock_net(sk), user, len);
1491                 break;
1492
1493         case ARPT_SO_GET_REVISION_TARGET: {
1494                 struct xt_get_revision rev;
1495
1496                 if (*len != sizeof(rev)) {
1497                         ret = -EINVAL;
1498                         break;
1499                 }
1500                 if (copy_from_user(&rev, user, sizeof(rev)) != 0) {
1501                         ret = -EFAULT;
1502                         break;
1503                 }
1504                 rev.name[sizeof(rev.name)-1] = 0;
1505
1506                 try_then_request_module(xt_find_revision(NFPROTO_ARP, rev.name,
1507                                                          rev.revision, 1, &ret),
1508                                         "arpt_%s", rev.name);
1509                 break;
1510         }
1511
1512         default:
1513                 ret = -EINVAL;
1514         }
1515
1516         return ret;
1517 }
1518
1519 static void __arpt_unregister_table(struct xt_table *table)
1520 {
1521         struct xt_table_info *private;
1522         void *loc_cpu_entry;
1523         struct module *table_owner = table->me;
1524         struct arpt_entry *iter;
1525
1526         private = xt_unregister_table(table);
1527
1528         /* Decrease module usage counts and free resources */
1529         loc_cpu_entry = private->entries;
1530         xt_entry_foreach(iter, loc_cpu_entry, private->size)
1531                 cleanup_entry(iter);
1532         if (private->number > private->initial_entries)
1533                 module_put(table_owner);
1534         xt_free_table_info(private);
1535 }
1536
1537 int arpt_register_table(struct net *net,
1538                         const struct xt_table *table,
1539                         const struct arpt_replace *repl,
1540                         const struct nf_hook_ops *ops,
1541                         struct xt_table **res)
1542 {
1543         int ret;
1544         struct xt_table_info *newinfo;
1545         struct xt_table_info bootstrap = {0};
1546         void *loc_cpu_entry;
1547         struct xt_table *new_table;
1548
1549         newinfo = xt_alloc_table_info(repl->size);
1550         if (!newinfo)
1551                 return -ENOMEM;
1552
1553         loc_cpu_entry = newinfo->entries;
1554         memcpy(loc_cpu_entry, repl->entries, repl->size);
1555
1556         ret = translate_table(newinfo, loc_cpu_entry, repl);
1557         if (ret != 0)
1558                 goto out_free;
1559
1560         new_table = xt_register_table(net, table, &bootstrap, newinfo);
1561         if (IS_ERR(new_table)) {
1562                 ret = PTR_ERR(new_table);
1563                 goto out_free;
1564         }
1565
1566         /* set res now, will see skbs right after nf_register_net_hooks */
1567         WRITE_ONCE(*res, new_table);
1568
1569         ret = nf_register_net_hooks(net, ops, hweight32(table->valid_hooks));
1570         if (ret != 0) {
1571                 __arpt_unregister_table(new_table);
1572                 *res = NULL;
1573         }
1574
1575         return ret;
1576
1577 out_free:
1578         xt_free_table_info(newinfo);
1579         return ret;
1580 }
1581
1582 void arpt_unregister_table(struct net *net, struct xt_table *table,
1583                            const struct nf_hook_ops *ops)
1584 {
1585         nf_unregister_net_hooks(net, ops, hweight32(table->valid_hooks));
1586         __arpt_unregister_table(table);
1587 }
1588
1589 /* The built-in targets: standard (NULL) and error. */
1590 static struct xt_target arpt_builtin_tg[] __read_mostly = {
1591         {
1592                 .name             = XT_STANDARD_TARGET,
1593                 .targetsize       = sizeof(int),
1594                 .family           = NFPROTO_ARP,
1595 #ifdef CONFIG_COMPAT
1596                 .compatsize       = sizeof(compat_int_t),
1597                 .compat_from_user = compat_standard_from_user,
1598                 .compat_to_user   = compat_standard_to_user,
1599 #endif
1600         },
1601         {
1602                 .name             = XT_ERROR_TARGET,
1603                 .target           = arpt_error,
1604                 .targetsize       = XT_FUNCTION_MAXNAMELEN,
1605                 .family           = NFPROTO_ARP,
1606         },
1607 };
1608
1609 static struct nf_sockopt_ops arpt_sockopts = {
1610         .pf             = PF_INET,
1611         .set_optmin     = ARPT_BASE_CTL,
1612         .set_optmax     = ARPT_SO_SET_MAX+1,
1613         .set            = do_arpt_set_ctl,
1614 #ifdef CONFIG_COMPAT
1615         .compat_set     = compat_do_arpt_set_ctl,
1616 #endif
1617         .get_optmin     = ARPT_BASE_CTL,
1618         .get_optmax     = ARPT_SO_GET_MAX+1,
1619         .get            = do_arpt_get_ctl,
1620 #ifdef CONFIG_COMPAT
1621         .compat_get     = compat_do_arpt_get_ctl,
1622 #endif
1623         .owner          = THIS_MODULE,
1624 };
1625
1626 static int __net_init arp_tables_net_init(struct net *net)
1627 {
1628         return xt_proto_init(net, NFPROTO_ARP);
1629 }
1630
1631 static void __net_exit arp_tables_net_exit(struct net *net)
1632 {
1633         xt_proto_fini(net, NFPROTO_ARP);
1634 }
1635
1636 static struct pernet_operations arp_tables_net_ops = {
1637         .init = arp_tables_net_init,
1638         .exit = arp_tables_net_exit,
1639 };
1640
1641 static int __init arp_tables_init(void)
1642 {
1643         int ret;
1644
1645         ret = register_pernet_subsys(&arp_tables_net_ops);
1646         if (ret < 0)
1647                 goto err1;
1648
1649         /* No one else will be downing sem now, so we won't sleep */
1650         ret = xt_register_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1651         if (ret < 0)
1652                 goto err2;
1653
1654         /* Register setsockopt */
1655         ret = nf_register_sockopt(&arpt_sockopts);
1656         if (ret < 0)
1657                 goto err4;
1658
1659         pr_info("arp_tables: (C) 2002 David S. Miller\n");
1660         return 0;
1661
1662 err4:
1663         xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1664 err2:
1665         unregister_pernet_subsys(&arp_tables_net_ops);
1666 err1:
1667         return ret;
1668 }
1669
1670 static void __exit arp_tables_fini(void)
1671 {
1672         nf_unregister_sockopt(&arpt_sockopts);
1673         xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1674         unregister_pernet_subsys(&arp_tables_net_ops);
1675 }
1676
1677 EXPORT_SYMBOL(arpt_register_table);
1678 EXPORT_SYMBOL(arpt_unregister_table);
1679 EXPORT_SYMBOL(arpt_do_table);
1680
1681 module_init(arp_tables_init);
1682 module_exit(arp_tables_fini);