net/ipv4/netfilter/arp_tables.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Packet matching code for ARP packets.
   4  *
   5  * Based heavily, if not almost entirely, upon ip_tables.c framework.
   6  *
   7  * Some ARP specific bits are:
   8  *
   9  * Copyright (C) 2002 David S. Miller (davem@redhat.com)
  10  * Copyright (C) 2006-2009 Patrick McHardy <kaber@trash.net>
  11  *
  12  */
  13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14 #include <linux/kernel.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/netdevice.h>
  17 #include <linux/capability.h>
  18 #include <linux/if_arp.h>
  19 #include <linux/kmod.h>
  20 #include <linux/vmalloc.h>
  21 #include <linux/proc_fs.h>
  22 #include <linux/module.h>
  23 #include <linux/init.h>
  24 #include <linux/mutex.h>
  25 #include <linux/err.h>
  26 #include <net/compat.h>
  27 #include <net/sock.h>
  28 #include <linux/uaccess.h>
  29
  30 #include <linux/netfilter/x_tables.h>
  31 #include <linux/netfilter_arp/arp_tables.h>
  32 #include "../../netfilter/xt_repldata.h"
  33
  34 MODULE_LICENSE("GPL");
  35 MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
  36 MODULE_DESCRIPTION("arptables core");
  37
  38 void *arpt_alloc_initial_table(const struct xt_table *info)
  39 {
  40         return xt_alloc_initial_table(arpt, ARPT);
  41 }
  42 EXPORT_SYMBOL_GPL(arpt_alloc_initial_table);
  43
  44 static inline int arp_devaddr_compare(const struct arpt_devaddr_info *ap,
  45                                       const char *hdr_addr, int len)
  46 {
  47         int i, ret;
  48
  49         if (len > ARPT_DEV_ADDR_LEN_MAX)
  50                 len = ARPT_DEV_ADDR_LEN_MAX;
  51
  52         ret = 0;
  53         for (i = 0; i < len; i++)
  54                 ret |= (hdr_addr[i] ^ ap->addr[i]) & ap->mask[i];
  55
  56         return ret != 0;
  57 }
  58
  59 /*
  60  * Unfortunately, _b and _mask are not aligned to an int (or long int)
  61  * Some arches dont care, unrolling the loop is a win on them.
  62  * For other arches, we only have a 16bit alignement.
  63  */
  64 static unsigned long ifname_compare(const char *_a, const char *_b, const char *_mask)
  65 {
  66 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
  67         unsigned long ret = ifname_compare_aligned(_a, _b, _mask);
  68 #else
  69         unsigned long ret = 0;
  70         const u16 *a = (const u16 *)_a;
  71         const u16 *b = (const u16 *)_b;
  72         const u16 *mask = (const u16 *)_mask;
  73         int i;
  74
  75         for (i = 0; i < IFNAMSIZ/sizeof(u16); i++)
  76                 ret |= (a[i] ^ b[i]) & mask[i];
  77 #endif
  78         return ret;
  79 }
  80
  81 /* Returns whether packet matches rule or not. */
  82 static inline int arp_packet_match(const struct arphdr *arphdr,
  83                                    struct net_device *dev,
  84                                    const char *indev,
  85                                    const char *outdev,
  86                                    const struct arpt_arp *arpinfo)
  87 {
  88         const char *arpptr = (char *)(arphdr + 1);
  89         const char *src_devaddr, *tgt_devaddr;
  90         __be32 src_ipaddr, tgt_ipaddr;
  91         long ret;
  92
  93         if (NF_INVF(arpinfo, ARPT_INV_ARPOP,
  94                     (arphdr->ar_op & arpinfo->arpop_mask) != arpinfo->arpop))
  95                 return 0;
  96
  97         if (NF_INVF(arpinfo, ARPT_INV_ARPHRD,
  98                     (arphdr->ar_hrd & arpinfo->arhrd_mask) != arpinfo->arhrd))
  99                 return 0;
 100
 101         if (NF_INVF(arpinfo, ARPT_INV_ARPPRO,
 102                     (arphdr->ar_pro & arpinfo->arpro_mask) != arpinfo->arpro))
 103                 return 0;
 104
 105         if (NF_INVF(arpinfo, ARPT_INV_ARPHLN,
 106                     (arphdr->ar_hln & arpinfo->arhln_mask) != arpinfo->arhln))
 107                 return 0;
 108
 109         src_devaddr = arpptr;
 110         arpptr += dev->addr_len;
 111         memcpy(&src_ipaddr, arpptr, sizeof(u32));
 112         arpptr += sizeof(u32);
 113         tgt_devaddr = arpptr;
 114         arpptr += dev->addr_len;
 115         memcpy(&tgt_ipaddr, arpptr, sizeof(u32));
 116
 117         if (NF_INVF(arpinfo, ARPT_INV_SRCDEVADDR,
 118                     arp_devaddr_compare(&arpinfo->src_devaddr, src_devaddr,
 119                                         dev->addr_len)) ||
 120             NF_INVF(arpinfo, ARPT_INV_TGTDEVADDR,
 121                     arp_devaddr_compare(&arpinfo->tgt_devaddr, tgt_devaddr,
 122                                         dev->addr_len)))
 123                 return 0;
 124
 125         if (NF_INVF(arpinfo, ARPT_INV_SRCIP,
 126                     (src_ipaddr & arpinfo->smsk.s_addr) != arpinfo->src.s_addr) ||
 127             NF_INVF(arpinfo, ARPT_INV_TGTIP,
 128                     (tgt_ipaddr & arpinfo->tmsk.s_addr) != arpinfo->tgt.s_addr))
 129                 return 0;
 130
 131         /* Look for ifname matches.  */
 132         ret = ifname_compare(indev, arpinfo->iniface, arpinfo->iniface_mask);
 133
 134         if (NF_INVF(arpinfo, ARPT_INV_VIA_IN, ret != 0))
 135                 return 0;
 136
 137         ret = ifname_compare(outdev, arpinfo->outiface, arpinfo->outiface_mask);
 138
 139         if (NF_INVF(arpinfo, ARPT_INV_VIA_OUT, ret != 0))
 140                 return 0;
 141
 142         return 1;
 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 = rcu_access_pointer(table->private);
 207         cpu     = smp_processor_id();
 208         table_base = private->entries;
 209         jumpstack  = (struct arpt_entry **)private->jumpstack[cpu];
 210
 211         /* No TEE support for arptables, so no need to switch to alternate
 212          * stack.  All targets that reenter must return absolute verdicts.
 213          */
 214         e = get_entry(table_base, private->hook_entry[hook]);
 215
 216         acpar.state   = state;
 217         acpar.hotdrop = false;
 218
 219         arp = arp_hdr(skb);
 220         do {
 221                 const struct xt_entry_target *t;
 222                 struct xt_counters *counter;
 223
 224                 if (!arp_packet_match(arp, skb->dev, indev, outdev, &e->arp)) {
 225                         e = arpt_next_entry(e);
 226                         continue;
 227                 }
 228
 229                 counter = xt_get_this_cpu_counter(&e->counters);
 230                 ADD_COUNTER(*counter, arp_hdr_len(skb->dev), 1);
 231
 232                 t = arpt_get_target_c(e);
 233
 234                 /* Standard target? */
 235                 if (!t->u.kernel.target->target) {
 236                         int v;
 237
 238                         v = ((struct xt_standard_target *)t)->verdict;
 239                         if (v < 0) {
 240                                 /* Pop from stack? */
 241                                 if (v != XT_RETURN) {
 242                                         verdict = (unsigned int)(-v) - 1;
 243                                         break;
 244                                 }
 245                                 if (stackidx == 0) {
 246                                         e = get_entry(table_base,
 247                                                       private->underflow[hook]);
 248                                 } else {
 249                                         e = jumpstack[--stackidx];
 250                                         e = arpt_next_entry(e);
 251                                 }
 252                                 continue;
 253                         }
 254                         if (table_base + v
 255                             != arpt_next_entry(e)) {
 256                                 if (unlikely(stackidx >= private->stacksize)) {
 257                                         verdict = NF_DROP;
 258                                         break;
 259                                 }
 260                                 jumpstack[stackidx++] = e;
 261                         }
 262
 263                         e = get_entry(table_base, v);
 264                         continue;
 265                 }
 266
 267                 acpar.target   = t->u.kernel.target;
 268                 acpar.targinfo = t->data;
 269                 verdict = t->u.kernel.target->target(skb, &acpar);
 270
 271                 if (verdict == XT_CONTINUE) {
 272                         /* Target might have changed stuff. */
 273                         arp = arp_hdr(skb);
 274                         e = arpt_next_entry(e);
 275                 } else {
 276                         /* Verdict */
 277                         break;
 278                 }
 279         } while (!acpar.hotdrop);
 280         xt_write_recseq_end(addend);
 281         local_bh_enable();
 282
 283         if (acpar.hotdrop)
 284                 return NF_DROP;
 285         else
 286                 return verdict;
 287 }
 288
 289 /* All zeroes == unconditional rule. */
 290 static inline bool unconditional(const struct arpt_entry *e)
 291 {
 292         static const struct arpt_arp uncond;
 293
 294         return e->target_offset == sizeof(struct arpt_entry) &&
 295                memcmp(&e->arp, &uncond, sizeof(uncond)) == 0;
 296 }
 297
 298 /* Figures out from what hook each rule can be called: returns 0 if
 299  * there are loops.  Puts hook bitmask in comefrom.
 300  */
 301 static int mark_source_chains(const struct xt_table_info *newinfo,
 302                               unsigned int valid_hooks, void *entry0,
 303                               unsigned int *offsets)
 304 {
 305         unsigned int hook;
 306
 307         /* No recursion; use packet counter to save back ptrs (reset
 308          * to 0 as we leave), and comefrom to save source hook bitmask.
 309          */
 310         for (hook = 0; hook < NF_ARP_NUMHOOKS; hook++) {
 311                 unsigned int pos = newinfo->hook_entry[hook];
 312                 struct arpt_entry *e = entry0 + pos;
 313
 314                 if (!(valid_hooks & (1 << hook)))
 315                         continue;
 316
 317                 /* Set initial back pointer. */
 318                 e->counters.pcnt = pos;
 319
 320                 for (;;) {
 321                         const struct xt_standard_target *t
 322                                 = (void *)arpt_get_target_c(e);
 323                         int visited = e->comefrom & (1 << hook);
 324
 325                         if (e->comefrom & (1 << NF_ARP_NUMHOOKS))
 326                                 return 0;
 327
 328                         e->comefrom
 329                                 |= ((1 << hook) | (1 << NF_ARP_NUMHOOKS));
 330
 331                         /* Unconditional return/END. */
 332                         if ((unconditional(e) &&
 333                              (strcmp(t->target.u.user.name,
 334                                      XT_STANDARD_TARGET) == 0) &&
 335                              t->verdict < 0) || visited) {
 336                                 unsigned int oldpos, size;
 337
 338                                 /* Return: backtrack through the last
 339                                  * big jump.
 340                                  */
 341                                 do {
 342                                         e->comefrom ^= (1<<NF_ARP_NUMHOOKS);
 343                                         oldpos = pos;
 344                                         pos = e->counters.pcnt;
 345                                         e->counters.pcnt = 0;
 346
 347                                         /* We're at the start. */
 348                                         if (pos == oldpos)
 349                                                 goto next;
 350
 351                                         e = entry0 + pos;
 352                                 } while (oldpos == pos + e->next_offset);
 353
 354                                 /* Move along one */
 355                                 size = e->next_offset;
 356                                 e = entry0 + pos + size;
 357                                 if (pos + size >= newinfo->size)
 358                                         return 0;
 359                                 e->counters.pcnt = pos;
 360                                 pos += size;
 361                         } else {
 362                                 int newpos = t->verdict;
 363
 364                                 if (strcmp(t->target.u.user.name,
 365                                            XT_STANDARD_TARGET) == 0 &&
 366                                     newpos >= 0) {
 367                                         /* This a jump; chase it. */
 368                                         if (!xt_find_jump_offset(offsets, newpos,
 369                                                                  newinfo->number))
 370                                                 return 0;
 371                                 } else {
 372                                         /* ... this is a fallthru */
 373                                         newpos = pos + e->next_offset;
 374                                         if (newpos >= newinfo->size)
 375                                                 return 0;
 376                                 }
 377                                 e = entry0 + newpos;
 378                                 e->counters.pcnt = pos;
 379                                 pos = newpos;
 380                         }
 381                 }
 382 next:           ;
 383         }
 384         return 1;
 385 }
 386
 387 static int check_target(struct arpt_entry *e, struct net *net, const char *name)
 388 {
 389         struct xt_entry_target *t = arpt_get_target(e);
 390         struct xt_tgchk_param par = {
 391                 .net       = net,
 392                 .table     = name,
 393                 .entryinfo = e,
 394                 .target    = t->u.kernel.target,
 395                 .targinfo  = t->data,
 396                 .hook_mask = e->comefrom,
 397                 .family    = NFPROTO_ARP,
 398         };
 399
 400         return xt_check_target(&par, t->u.target_size - sizeof(*t), 0, false);
 401 }
 402
 403 static int
 404 find_check_entry(struct arpt_entry *e, struct net *net, const char *name,
 405                  unsigned int size,
 406                  struct xt_percpu_counter_alloc_state *alloc_state)
 407 {
 408         struct xt_entry_target *t;
 409         struct xt_target *target;
 410         int ret;
 411
 412         if (!xt_percpu_counter_alloc(alloc_state, &e->counters))
 413                 return -ENOMEM;
 414
 415         t = arpt_get_target(e);
 416         target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
 417                                         t->u.user.revision);
 418         if (IS_ERR(target)) {
 419                 ret = PTR_ERR(target);
 420                 goto out;
 421         }
 422         t->u.kernel.target = target;
 423
 424         ret = check_target(e, net, name);
 425         if (ret)
 426                 goto err;
 427         return 0;
 428 err:
 429         module_put(t->u.kernel.target->me);
 430 out:
 431         xt_percpu_counter_free(&e->counters);
 432
 433         return ret;
 434 }
 435
 436 static bool check_underflow(const struct arpt_entry *e)
 437 {
 438         const struct xt_entry_target *t;
 439         unsigned int verdict;
 440
 441         if (!unconditional(e))
 442                 return false;
 443         t = arpt_get_target_c(e);
 444         if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
 445                 return false;
 446         verdict = ((struct xt_standard_target *)t)->verdict;
 447         verdict = -verdict - 1;
 448         return verdict == NF_DROP || verdict == NF_ACCEPT;
 449 }
 450
 451 static inline int check_entry_size_and_hooks(struct arpt_entry *e,
 452                                              struct xt_table_info *newinfo,
 453                                              const unsigned char *base,
 454                                              const unsigned char *limit,
 455                                              const unsigned int *hook_entries,
 456                                              const unsigned int *underflows,
 457                                              unsigned int valid_hooks)
 458 {
 459         unsigned int h;
 460         int err;
 461
 462         if ((unsigned long)e % __alignof__(struct arpt_entry) != 0 ||
 463             (unsigned char *)e + sizeof(struct arpt_entry) >= limit ||
 464             (unsigned char *)e + e->next_offset > limit)
 465                 return -EINVAL;
 466
 467         if (e->next_offset
 468             < sizeof(struct arpt_entry) + sizeof(struct xt_entry_target))
 469                 return -EINVAL;
 470
 471         if (!arp_checkentry(&e->arp))
 472                 return -EINVAL;
 473
 474         err = xt_check_entry_offsets(e, e->elems, e->target_offset,
 475                                      e->next_offset);
 476         if (err)
 477                 return err;
 478
 479         /* Check hooks & underflows */
 480         for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
 481                 if (!(valid_hooks & (1 << h)))
 482                         continue;
 483                 if ((unsigned char *)e - base == hook_entries[h])
 484                         newinfo->hook_entry[h] = hook_entries[h];
 485                 if ((unsigned char *)e - base == underflows[h]) {
 486                         if (!check_underflow(e))
 487                                 return -EINVAL;
 488
 489                         newinfo->underflow[h] = underflows[h];
 490                 }
 491         }
 492
 493         /* Clear counters and comefrom */
 494         e->counters = ((struct xt_counters) { 0, 0 });
 495         e->comefrom = 0;
 496         return 0;
 497 }
 498
 499 static void cleanup_entry(struct arpt_entry *e, struct net *net)
 500 {
 501         struct xt_tgdtor_param par;
 502         struct xt_entry_target *t;
 503
 504         t = arpt_get_target(e);
 505         par.net      = net;
 506         par.target   = t->u.kernel.target;
 507         par.targinfo = t->data;
 508         par.family   = NFPROTO_ARP;
 509         if (par.target->destroy != NULL)
 510                 par.target->destroy(&par);
 511         module_put(par.target->me);
 512         xt_percpu_counter_free(&e->counters);
 513 }
 514
 515 /* Checks and translates the user-supplied table segment (held in
 516  * newinfo).
 517  */
 518 static int translate_table(struct net *net,
 519                            struct xt_table_info *newinfo,
 520                            void *entry0,
 521                            const struct arpt_replace *repl)
 522 {
 523         struct xt_percpu_counter_alloc_state alloc_state = { 0 };
 524         struct arpt_entry *iter;
 525         unsigned int *offsets;
 526         unsigned int i;
 527         int ret = 0;
 528
 529         newinfo->size = repl->size;
 530         newinfo->number = repl->num_entries;
 531
 532         /* Init all hooks to impossible value. */
 533         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
 534                 newinfo->hook_entry[i] = 0xFFFFFFFF;
 535                 newinfo->underflow[i] = 0xFFFFFFFF;
 536         }
 537
 538         offsets = xt_alloc_entry_offsets(newinfo->number);
 539         if (!offsets)
 540                 return -ENOMEM;
 541         i = 0;
 542
 543         /* Walk through entries, checking offsets. */
 544         xt_entry_foreach(iter, entry0, newinfo->size) {
 545                 ret = check_entry_size_and_hooks(iter, newinfo, entry0,
 546                                                  entry0 + repl->size,
 547                                                  repl->hook_entry,
 548                                                  repl->underflow,
 549                                                  repl->valid_hooks);
 550                 if (ret != 0)
 551                         goto out_free;
 552                 if (i < repl->num_entries)
 553                         offsets[i] = (void *)iter - entry0;
 554                 ++i;
 555                 if (strcmp(arpt_get_target(iter)->u.user.name,
 556                     XT_ERROR_TARGET) == 0)
 557                         ++newinfo->stacksize;
 558         }
 559
 560         ret = -EINVAL;
 561         if (i != repl->num_entries)
 562                 goto out_free;
 563
 564         ret = xt_check_table_hooks(newinfo, repl->valid_hooks);
 565         if (ret)
 566                 goto out_free;
 567
 568         if (!mark_source_chains(newinfo, repl->valid_hooks, entry0, offsets)) {
 569                 ret = -ELOOP;
 570                 goto out_free;
 571         }
 572         kvfree(offsets);
 573
 574         /* Finally, each sanity check must pass */
 575         i = 0;
 576         xt_entry_foreach(iter, entry0, newinfo->size) {
 577                 ret = find_check_entry(iter, net, repl->name, repl->size,
 578                                        &alloc_state);
 579                 if (ret != 0)
 580                         break;
 581                 ++i;
 582         }
 583
 584         if (ret != 0) {
 585                 xt_entry_foreach(iter, entry0, newinfo->size) {
 586                         if (i-- == 0)
 587                                 break;
 588                         cleanup_entry(iter, net);
 589                 }
 590                 return ret;
 591         }
 592
 593         return ret;
 594  out_free:
 595         kvfree(offsets);
 596         return ret;
 597 }
 598
 599 static void get_counters(const struct xt_table_info *t,
 600                          struct xt_counters counters[])
 601 {
 602         struct arpt_entry *iter;
 603         unsigned int cpu;
 604         unsigned int i;
 605
 606         for_each_possible_cpu(cpu) {
 607                 seqcount_t *s = &per_cpu(xt_recseq, cpu);
 608
 609                 i = 0;
 610                 xt_entry_foreach(iter, t->entries, t->size) {
 611                         struct xt_counters *tmp;
 612                         u64 bcnt, pcnt;
 613                         unsigned int start;
 614
 615                         tmp = xt_get_per_cpu_counter(&iter->counters, cpu);
 616                         do {
 617                                 start = read_seqcount_begin(s);
 618                                 bcnt = tmp->bcnt;
 619                                 pcnt = tmp->pcnt;
 620                         } while (read_seqcount_retry(s, start));
 621
 622                         ADD_COUNTER(counters[i], bcnt, pcnt);
 623                         ++i;
 624                         cond_resched();
 625                 }
 626         }
 627 }
 628
 629 static void get_old_counters(const struct xt_table_info *t,
 630                              struct xt_counters counters[])
 631 {
 632         struct arpt_entry *iter;
 633         unsigned int cpu, i;
 634
 635         for_each_possible_cpu(cpu) {
 636                 i = 0;
 637                 xt_entry_foreach(iter, t->entries, t->size) {
 638                         struct xt_counters *tmp;
 639
 640                         tmp = xt_get_per_cpu_counter(&iter->counters, cpu);
 641                         ADD_COUNTER(counters[i], tmp->bcnt, tmp->pcnt);
 642                         ++i;
 643                 }
 644                 cond_resched();
 645         }
 646 }
 647
 648 static struct xt_counters *alloc_counters(const struct xt_table *table)
 649 {
 650         unsigned int countersize;
 651         struct xt_counters *counters;
 652         const struct xt_table_info *private = xt_table_get_private_protected(table);
 653
 654         /* We need atomic snapshot of counters: rest doesn't change
 655          * (other than comefrom, which userspace doesn't care
 656          * about).
 657          */
 658         countersize = sizeof(struct xt_counters) * private->number;
 659         counters = vzalloc(countersize);
 660
 661         if (counters == NULL)
 662                 return ERR_PTR(-ENOMEM);
 663
 664         get_counters(private, counters);
 665
 666         return counters;
 667 }
 668
 669 static int copy_entries_to_user(unsigned int total_size,
 670                                 const struct xt_table *table,
 671                                 void __user *userptr)
 672 {
 673         unsigned int off, num;
 674         const struct arpt_entry *e;
 675         struct xt_counters *counters;
 676         struct xt_table_info *private = xt_table_get_private_protected(table);
 677         int ret = 0;
 678         void *loc_cpu_entry;
 679
 680         counters = alloc_counters(table);
 681         if (IS_ERR(counters))
 682                 return PTR_ERR(counters);
 683
 684         loc_cpu_entry = private->entries;
 685
 686         /* FIXME: use iterator macros --RR */
 687         /* ... then go back and fix counters and names */
 688         for (off = 0, num = 0; off < total_size; off += e->next_offset, num++){
 689                 const struct xt_entry_target *t;
 690
 691                 e = loc_cpu_entry + off;
 692                 if (copy_to_user(userptr + off, e, sizeof(*e))) {
 693                         ret = -EFAULT;
 694                         goto free_counters;
 695                 }
 696                 if (copy_to_user(userptr + off
 697                                  + offsetof(struct arpt_entry, counters),
 698                                  &counters[num],
 699                                  sizeof(counters[num])) != 0) {
 700                         ret = -EFAULT;
 701                         goto free_counters;
 702                 }
 703
 704                 t = arpt_get_target_c(e);
 705                 if (xt_target_to_user(t, userptr + off + e->target_offset)) {
 706                         ret = -EFAULT;
 707                         goto free_counters;
 708                 }
 709         }
 710
 711  free_counters:
 712         vfree(counters);
 713         return ret;
 714 }
 715
 716 #ifdef CONFIG_COMPAT
 717 static void compat_standard_from_user(void *dst, const void *src)
 718 {
 719         int v = *(compat_int_t *)src;
 720
 721         if (v > 0)
 722                 v += xt_compat_calc_jump(NFPROTO_ARP, v);
 723         memcpy(dst, &v, sizeof(v));
 724 }
 725
 726 static int compat_standard_to_user(void __user *dst, const void *src)
 727 {
 728         compat_int_t cv = *(int *)src;
 729
 730         if (cv > 0)
 731                 cv -= xt_compat_calc_jump(NFPROTO_ARP, cv);
 732         return copy_to_user(dst, &cv, sizeof(cv)) ? -EFAULT : 0;
 733 }
 734
 735 static int compat_calc_entry(const struct arpt_entry *e,
 736                              const struct xt_table_info *info,
 737                              const void *base, struct xt_table_info *newinfo)
 738 {
 739         const struct xt_entry_target *t;
 740         unsigned int entry_offset;
 741         int off, i, ret;
 742
 743         off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
 744         entry_offset = (void *)e - base;
 745
 746         t = arpt_get_target_c(e);
 747         off += xt_compat_target_offset(t->u.kernel.target);
 748         newinfo->size -= off;
 749         ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
 750         if (ret)
 751                 return ret;
 752
 753         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
 754                 if (info->hook_entry[i] &&
 755                     (e < (struct arpt_entry *)(base + info->hook_entry[i])))
 756                         newinfo->hook_entry[i] -= off;
 757                 if (info->underflow[i] &&
 758                     (e < (struct arpt_entry *)(base + info->underflow[i])))
 759                         newinfo->underflow[i] -= off;
 760         }
 761         return 0;
 762 }
 763
 764 static int compat_table_info(const struct xt_table_info *info,
 765                              struct xt_table_info *newinfo)
 766 {
 767         struct arpt_entry *iter;
 768         const void *loc_cpu_entry;
 769         int ret;
 770
 771         if (!newinfo || !info)
 772                 return -EINVAL;
 773
 774         /* we dont care about newinfo->entries */
 775         memcpy(newinfo, info, offsetof(struct xt_table_info, entries));
 776         newinfo->initial_entries = 0;
 777         loc_cpu_entry = info->entries;
 778         ret = xt_compat_init_offsets(NFPROTO_ARP, info->number);
 779         if (ret)
 780                 return ret;
 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, const int *len)
 791 {
 792         char name[XT_TABLE_MAXNAMELEN];
 793         struct xt_table *t;
 794         int ret;
 795
 796         if (*len != sizeof(struct arpt_getinfo))
 797                 return -EINVAL;
 798
 799         if (copy_from_user(name, user, sizeof(name)) != 0)
 800                 return -EFAULT;
 801
 802         name[XT_TABLE_MAXNAMELEN-1] = '\0';
 803 #ifdef CONFIG_COMPAT
 804         if (in_compat_syscall())
 805                 xt_compat_lock(NFPROTO_ARP);
 806 #endif
 807         t = xt_request_find_table_lock(net, NFPROTO_ARP, name);
 808         if (!IS_ERR(t)) {
 809                 struct arpt_getinfo info;
 810                 const struct xt_table_info *private = xt_table_get_private_protected(t);
 811 #ifdef CONFIG_COMPAT
 812                 struct xt_table_info tmp;
 813
 814                 if (in_compat_syscall()) {
 815                         ret = compat_table_info(private, &tmp);
 816                         xt_compat_flush_offsets(NFPROTO_ARP);
 817                         private = &tmp;
 818                 }
 819 #endif
 820                 memset(&info, 0, sizeof(info));
 821                 info.valid_hooks = t->valid_hooks;
 822                 memcpy(info.hook_entry, private->hook_entry,
 823                        sizeof(info.hook_entry));
 824                 memcpy(info.underflow, private->underflow,
 825                        sizeof(info.underflow));
 826                 info.num_entries = private->number;
 827                 info.size = private->size;
 828                 strcpy(info.name, name);
 829
 830                 if (copy_to_user(user, &info, *len) != 0)
 831                         ret = -EFAULT;
 832                 else
 833                         ret = 0;
 834                 xt_table_unlock(t);
 835                 module_put(t->me);
 836         } else
 837                 ret = PTR_ERR(t);
 838 #ifdef CONFIG_COMPAT
 839         if (in_compat_syscall())
 840                 xt_compat_unlock(NFPROTO_ARP);
 841 #endif
 842         return ret;
 843 }
 844
 845 static int get_entries(struct net *net, struct arpt_get_entries __user *uptr,
 846                        const int *len)
 847 {
 848         int ret;
 849         struct arpt_get_entries get;
 850         struct xt_table *t;
 851
 852         if (*len < sizeof(get))
 853                 return -EINVAL;
 854         if (copy_from_user(&get, uptr, sizeof(get)) != 0)
 855                 return -EFAULT;
 856         if (*len != sizeof(struct arpt_get_entries) + get.size)
 857                 return -EINVAL;
 858
 859         get.name[sizeof(get.name) - 1] = '\0';
 860
 861         t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
 862         if (!IS_ERR(t)) {
 863                 const struct xt_table_info *private = xt_table_get_private_protected(t);
 864
 865                 if (get.size == private->size)
 866                         ret = copy_entries_to_user(private->size,
 867                                                    t, uptr->entrytable);
 868                 else
 869                         ret = -EAGAIN;
 870
 871                 module_put(t->me);
 872                 xt_table_unlock(t);
 873         } else
 874                 ret = PTR_ERR(t);
 875
 876         return ret;
 877 }
 878
 879 static int __do_replace(struct net *net, const char *name,
 880                         unsigned int valid_hooks,
 881                         struct xt_table_info *newinfo,
 882                         unsigned int num_counters,
 883                         void __user *counters_ptr)
 884 {
 885         int ret;
 886         struct xt_table *t;
 887         struct xt_table_info *oldinfo;
 888         struct xt_counters *counters;
 889         void *loc_cpu_old_entry;
 890         struct arpt_entry *iter;
 891
 892         ret = 0;
 893         counters = xt_counters_alloc(num_counters);
 894         if (!counters) {
 895                 ret = -ENOMEM;
 896                 goto out;
 897         }
 898
 899         t = xt_request_find_table_lock(net, NFPROTO_ARP, name);
 900         if (IS_ERR(t)) {
 901                 ret = PTR_ERR(t);
 902                 goto free_newinfo_counters_untrans;
 903         }
 904
 905         /* You lied! */
 906         if (valid_hooks != t->valid_hooks) {
 907                 ret = -EINVAL;
 908                 goto put_module;
 909         }
 910
 911         oldinfo = xt_replace_table(t, num_counters, newinfo, &ret);
 912         if (!oldinfo)
 913                 goto put_module;
 914
 915         /* Update module usage count based on number of rules */
 916         if ((oldinfo->number > oldinfo->initial_entries) ||
 917             (newinfo->number <= oldinfo->initial_entries))
 918                 module_put(t->me);
 919         if ((oldinfo->number > oldinfo->initial_entries) &&
 920             (newinfo->number <= oldinfo->initial_entries))
 921                 module_put(t->me);
 922
 923         xt_table_unlock(t);
 924
 925         get_old_counters(oldinfo, counters);
 926
 927         /* Decrease module usage counts and free resource */
 928         loc_cpu_old_entry = oldinfo->entries;
 929         xt_entry_foreach(iter, loc_cpu_old_entry, oldinfo->size)
 930                 cleanup_entry(iter, net);
 931
 932         xt_free_table_info(oldinfo);
 933         if (copy_to_user(counters_ptr, counters,
 934                          sizeof(struct xt_counters) * num_counters) != 0) {
 935                 /* Silent error, can't fail, new table is already in place */
 936                 net_warn_ratelimited("arptables: counters copy to user failed while replacing table\n");
 937         }
 938         vfree(counters);
 939         return ret;
 940
 941  put_module:
 942         module_put(t->me);
 943         xt_table_unlock(t);
 944  free_newinfo_counters_untrans:
 945         vfree(counters);
 946  out:
 947         return ret;
 948 }
 949
 950 static int do_replace(struct net *net, sockptr_t arg, unsigned int len)
 951 {
 952         int ret;
 953         struct arpt_replace tmp;
 954         struct xt_table_info *newinfo;
 955         void *loc_cpu_entry;
 956         struct arpt_entry *iter;
 957
 958         if (copy_from_sockptr(&tmp, arg, sizeof(tmp)) != 0)
 959                 return -EFAULT;
 960
 961         /* overflow check */
 962         if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
 963                 return -ENOMEM;
 964         if (tmp.num_counters == 0)
 965                 return -EINVAL;
 966
 967         tmp.name[sizeof(tmp.name)-1] = 0;
 968
 969         newinfo = xt_alloc_table_info(tmp.size);
 970         if (!newinfo)
 971                 return -ENOMEM;
 972
 973         loc_cpu_entry = newinfo->entries;
 974         if (copy_from_sockptr_offset(loc_cpu_entry, arg, sizeof(tmp),
 975                         tmp.size) != 0) {
 976                 ret = -EFAULT;
 977                 goto free_newinfo;
 978         }
 979
 980         ret = translate_table(net, newinfo, loc_cpu_entry, &tmp);
 981         if (ret != 0)
 982                 goto free_newinfo;
 983
 984         ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
 985                            tmp.num_counters, tmp.counters);
 986         if (ret)
 987                 goto free_newinfo_untrans;
 988         return 0;
 989
 990  free_newinfo_untrans:
 991         xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
 992                 cleanup_entry(iter, net);
 993  free_newinfo:
 994         xt_free_table_info(newinfo);
 995         return ret;
 996 }
 997
 998 static int do_add_counters(struct net *net, sockptr_t arg, unsigned int len)
 999 {
1000         unsigned int i;
1001         struct xt_counters_info tmp;
1002         struct xt_counters *paddc;
1003         struct xt_table *t;
1004         const struct xt_table_info *private;
1005         int ret = 0;
1006         struct arpt_entry *iter;
1007         unsigned int addend;
1008
1009         paddc = xt_copy_counters(arg, len, &tmp);
1010         if (IS_ERR(paddc))
1011                 return PTR_ERR(paddc);
1012
1013         t = xt_find_table_lock(net, NFPROTO_ARP, tmp.name);
1014         if (IS_ERR(t)) {
1015                 ret = PTR_ERR(t);
1016                 goto free;
1017         }
1018
1019         local_bh_disable();
1020         private = xt_table_get_private_protected(t);
1021         if (private->number != tmp.num_counters) {
1022                 ret = -EINVAL;
1023                 goto unlock_up_free;
1024         }
1025
1026         i = 0;
1027
1028         addend = xt_write_recseq_begin();
1029         xt_entry_foreach(iter,  private->entries, private->size) {
1030                 struct xt_counters *tmp;
1031
1032                 tmp = xt_get_this_cpu_counter(&iter->counters);
1033                 ADD_COUNTER(*tmp, paddc[i].bcnt, paddc[i].pcnt);
1034                 ++i;
1035         }
1036         xt_write_recseq_end(addend);
1037  unlock_up_free:
1038         local_bh_enable();
1039         xt_table_unlock(t);
1040         module_put(t->me);
1041  free:
1042         vfree(paddc);
1043
1044         return ret;
1045 }
1046
1047 #ifdef CONFIG_COMPAT
1048 struct compat_arpt_replace {
1049         char                            name[XT_TABLE_MAXNAMELEN];
1050         u32                             valid_hooks;
1051         u32                             num_entries;
1052         u32                             size;
1053         u32                             hook_entry[NF_ARP_NUMHOOKS];
1054         u32                             underflow[NF_ARP_NUMHOOKS];
1055         u32                             num_counters;
1056         compat_uptr_t                   counters;
1057         struct compat_arpt_entry        entries[];
1058 };
1059
1060 static inline void compat_release_entry(struct compat_arpt_entry *e)
1061 {
1062         struct xt_entry_target *t;
1063
1064         t = compat_arpt_get_target(e);
1065         module_put(t->u.kernel.target->me);
1066 }
1067
1068 static int
1069 check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
1070                                   struct xt_table_info *newinfo,
1071                                   unsigned int *size,
1072                                   const unsigned char *base,
1073                                   const unsigned char *limit)
1074 {
1075         struct xt_entry_target *t;
1076         struct xt_target *target;
1077         unsigned int entry_offset;
1078         int ret, off;
1079
1080         if ((unsigned long)e % __alignof__(struct compat_arpt_entry) != 0 ||
1081             (unsigned char *)e + sizeof(struct compat_arpt_entry) >= limit ||
1082             (unsigned char *)e + e->next_offset > limit)
1083                 return -EINVAL;
1084
1085         if (e->next_offset < sizeof(struct compat_arpt_entry) +
1086                              sizeof(struct compat_xt_entry_target))
1087                 return -EINVAL;
1088
1089         if (!arp_checkentry(&e->arp))
1090                 return -EINVAL;
1091
1092         ret = xt_compat_check_entry_offsets(e, e->elems, e->target_offset,
1093                                             e->next_offset);
1094         if (ret)
1095                 return ret;
1096
1097         off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1098         entry_offset = (void *)e - (void *)base;
1099
1100         t = compat_arpt_get_target(e);
1101         target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
1102                                         t->u.user.revision);
1103         if (IS_ERR(target)) {
1104                 ret = PTR_ERR(target);
1105                 goto out;
1106         }
1107         t->u.kernel.target = target;
1108
1109         off += xt_compat_target_offset(target);
1110         *size += off;
1111         ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
1112         if (ret)
1113                 goto release_target;
1114
1115         return 0;
1116
1117 release_target:
1118         module_put(t->u.kernel.target->me);
1119 out:
1120         return ret;
1121 }
1122
1123 static void
1124 compat_copy_entry_from_user(struct compat_arpt_entry *e, void **dstptr,
1125                             unsigned int *size,
1126                             struct xt_table_info *newinfo, unsigned char *base)
1127 {
1128         struct xt_entry_target *t;
1129         struct arpt_entry *de;
1130         unsigned int origsize;
1131         int h;
1132
1133         origsize = *size;
1134         de = *dstptr;
1135         memcpy(de, e, sizeof(struct arpt_entry));
1136         memcpy(&de->counters, &e->counters, sizeof(e->counters));
1137
1138         *dstptr += sizeof(struct arpt_entry);
1139         *size += sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1140
1141         de->target_offset = e->target_offset - (origsize - *size);
1142         t = compat_arpt_get_target(e);
1143         xt_compat_target_from_user(t, dstptr, size);
1144
1145         de->next_offset = e->next_offset - (origsize - *size);
1146         for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
1147                 if ((unsigned char *)de - base < newinfo->hook_entry[h])
1148                         newinfo->hook_entry[h] -= origsize - *size;
1149                 if ((unsigned char *)de - base < newinfo->underflow[h])
1150                         newinfo->underflow[h] -= origsize - *size;
1151         }
1152 }
1153
1154 static int translate_compat_table(struct net *net,
1155                                   struct xt_table_info **pinfo,
1156                                   void **pentry0,
1157                                   const struct compat_arpt_replace *compatr)
1158 {
1159         unsigned int i, j;
1160         struct xt_table_info *newinfo, *info;
1161         void *pos, *entry0, *entry1;
1162         struct compat_arpt_entry *iter0;
1163         struct arpt_replace repl;
1164         unsigned int size;
1165         int ret;
1166
1167         info = *pinfo;
1168         entry0 = *pentry0;
1169         size = compatr->size;
1170         info->number = compatr->num_entries;
1171
1172         j = 0;
1173         xt_compat_lock(NFPROTO_ARP);
1174         ret = xt_compat_init_offsets(NFPROTO_ARP, compatr->num_entries);
1175         if (ret)
1176                 goto out_unlock;
1177         /* Walk through entries, checking offsets. */
1178         xt_entry_foreach(iter0, entry0, compatr->size) {
1179                 ret = check_compat_entry_size_and_hooks(iter0, info, &size,
1180                                                         entry0,
1181                                                         entry0 + compatr->size);
1182                 if (ret != 0)
1183                         goto out_unlock;
1184                 ++j;
1185         }
1186
1187         ret = -EINVAL;
1188         if (j != compatr->num_entries)
1189                 goto out_unlock;
1190
1191         ret = -ENOMEM;
1192         newinfo = xt_alloc_table_info(size);
1193         if (!newinfo)
1194                 goto out_unlock;
1195
1196         newinfo->number = compatr->num_entries;
1197         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1198                 newinfo->hook_entry[i] = compatr->hook_entry[i];
1199                 newinfo->underflow[i] = compatr->underflow[i];
1200         }
1201         entry1 = newinfo->entries;
1202         pos = entry1;
1203         size = compatr->size;
1204         xt_entry_foreach(iter0, entry0, compatr->size)
1205                 compat_copy_entry_from_user(iter0, &pos, &size,
1206                                             newinfo, entry1);
1207
1208         /* all module references in entry0 are now gone */
1209
1210         xt_compat_flush_offsets(NFPROTO_ARP);
1211         xt_compat_unlock(NFPROTO_ARP);
1212
1213         memcpy(&repl, compatr, sizeof(*compatr));
1214
1215         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1216                 repl.hook_entry[i] = newinfo->hook_entry[i];
1217                 repl.underflow[i] = newinfo->underflow[i];
1218         }
1219
1220         repl.num_counters = 0;
1221         repl.counters = NULL;
1222         repl.size = newinfo->size;
1223         ret = translate_table(net, newinfo, entry1, &repl);
1224         if (ret)
1225                 goto free_newinfo;
1226
1227         *pinfo = newinfo;
1228         *pentry0 = entry1;
1229         xt_free_table_info(info);
1230         return 0;
1231
1232 free_newinfo:
1233         xt_free_table_info(newinfo);
1234         return ret;
1235 out_unlock:
1236         xt_compat_flush_offsets(NFPROTO_ARP);
1237         xt_compat_unlock(NFPROTO_ARP);
1238         xt_entry_foreach(iter0, entry0, compatr->size) {
1239                 if (j-- == 0)
1240                         break;
1241                 compat_release_entry(iter0);
1242         }
1243         return ret;
1244 }
1245
1246 static int compat_do_replace(struct net *net, sockptr_t arg, unsigned int len)
1247 {
1248         int ret;
1249         struct compat_arpt_replace tmp;
1250         struct xt_table_info *newinfo;
1251         void *loc_cpu_entry;
1252         struct arpt_entry *iter;
1253
1254         if (copy_from_sockptr(&tmp, arg, sizeof(tmp)) != 0)
1255                 return -EFAULT;
1256
1257         /* overflow check */
1258         if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
1259                 return -ENOMEM;
1260         if (tmp.num_counters == 0)
1261                 return -EINVAL;
1262
1263         tmp.name[sizeof(tmp.name)-1] = 0;
1264
1265         newinfo = xt_alloc_table_info(tmp.size);
1266         if (!newinfo)
1267                 return -ENOMEM;
1268
1269         loc_cpu_entry = newinfo->entries;
1270         if (copy_from_sockptr_offset(loc_cpu_entry, arg, sizeof(tmp),
1271                         tmp.size) != 0) {
1272                 ret = -EFAULT;
1273                 goto free_newinfo;
1274         }
1275
1276         ret = translate_compat_table(net, &newinfo, &loc_cpu_entry, &tmp);
1277         if (ret != 0)
1278                 goto free_newinfo;
1279
1280         ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
1281                            tmp.num_counters, compat_ptr(tmp.counters));
1282         if (ret)
1283                 goto free_newinfo_untrans;
1284         return 0;
1285
1286  free_newinfo_untrans:
1287         xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
1288                 cleanup_entry(iter, net);
1289  free_newinfo:
1290         xt_free_table_info(newinfo);
1291         return ret;
1292 }
1293
1294 static int compat_copy_entry_to_user(struct arpt_entry *e, void __user **dstptr,
1295                                      compat_uint_t *size,
1296                                      struct xt_counters *counters,
1297                                      unsigned int i)
1298 {
1299         struct xt_entry_target *t;
1300         struct compat_arpt_entry __user *ce;
1301         u_int16_t target_offset, next_offset;
1302         compat_uint_t origsize;
1303         int ret;
1304
1305         origsize = *size;
1306         ce = *dstptr;
1307         if (copy_to_user(ce, e, sizeof(struct arpt_entry)) != 0 ||
1308             copy_to_user(&ce->counters, &counters[i],
1309             sizeof(counters[i])) != 0)
1310                 return -EFAULT;
1311
1312         *dstptr += sizeof(struct compat_arpt_entry);
1313         *size -= sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1314
1315         target_offset = e->target_offset - (origsize - *size);
1316
1317         t = arpt_get_target(e);
1318         ret = xt_compat_target_to_user(t, dstptr, size);
1319         if (ret)
1320                 return ret;
1321         next_offset = e->next_offset - (origsize - *size);
1322         if (put_user(target_offset, &ce->target_offset) != 0 ||
1323             put_user(next_offset, &ce->next_offset) != 0)
1324                 return -EFAULT;
1325         return 0;
1326 }
1327
1328 static int compat_copy_entries_to_user(unsigned int total_size,
1329                                        struct xt_table *table,
1330                                        void __user *userptr)
1331 {
1332         struct xt_counters *counters;
1333         const struct xt_table_info *private = xt_table_get_private_protected(table);
1334         void __user *pos;
1335         unsigned int size;
1336         int ret = 0;
1337         unsigned int i = 0;
1338         struct arpt_entry *iter;
1339
1340         counters = alloc_counters(table);
1341         if (IS_ERR(counters))
1342                 return PTR_ERR(counters);
1343
1344         pos = userptr;
1345         size = total_size;
1346         xt_entry_foreach(iter, private->entries, total_size) {
1347                 ret = compat_copy_entry_to_user(iter, &pos,
1348                                                 &size, counters, i++);
1349                 if (ret != 0)
1350                         break;
1351         }
1352         vfree(counters);
1353         return ret;
1354 }
1355
1356 struct compat_arpt_get_entries {
1357         char name[XT_TABLE_MAXNAMELEN];
1358         compat_uint_t size;
1359         struct compat_arpt_entry entrytable[];
1360 };
1361
1362 static int compat_get_entries(struct net *net,
1363                               struct compat_arpt_get_entries __user *uptr,
1364                               int *len)
1365 {
1366         int ret;
1367         struct compat_arpt_get_entries get;
1368         struct xt_table *t;
1369
1370         if (*len < sizeof(get))
1371                 return -EINVAL;
1372         if (copy_from_user(&get, uptr, sizeof(get)) != 0)
1373                 return -EFAULT;
1374         if (*len != sizeof(struct compat_arpt_get_entries) + get.size)
1375                 return -EINVAL;
1376
1377         get.name[sizeof(get.name) - 1] = '\0';
1378
1379         xt_compat_lock(NFPROTO_ARP);
1380         t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
1381         if (!IS_ERR(t)) {
1382                 const struct xt_table_info *private = xt_table_get_private_protected(t);
1383                 struct xt_table_info info;
1384
1385                 ret = compat_table_info(private, &info);
1386                 if (!ret && get.size == info.size) {
1387                         ret = compat_copy_entries_to_user(private->size,
1388                                                           t, uptr->entrytable);
1389                 } else if (!ret)
1390                         ret = -EAGAIN;
1391
1392                 xt_compat_flush_offsets(NFPROTO_ARP);
1393                 module_put(t->me);
1394                 xt_table_unlock(t);
1395         } else
1396                 ret = PTR_ERR(t);
1397
1398         xt_compat_unlock(NFPROTO_ARP);
1399         return ret;
1400 }
1401 #endif
1402
1403 static int do_arpt_set_ctl(struct sock *sk, int cmd, sockptr_t arg,
1404                 unsigned int len)
1405 {
1406         int ret;
1407
1408         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1409                 return -EPERM;
1410
1411         switch (cmd) {
1412         case ARPT_SO_SET_REPLACE:
1413 #ifdef CONFIG_COMPAT
1414                 if (in_compat_syscall())
1415                         ret = compat_do_replace(sock_net(sk), arg, len);
1416                 else
1417 #endif
1418                         ret = do_replace(sock_net(sk), arg, len);
1419                 break;
1420
1421         case ARPT_SO_SET_ADD_COUNTERS:
1422                 ret = do_add_counters(sock_net(sk), arg, len);
1423                 break;
1424
1425         default:
1426                 ret = -EINVAL;
1427         }
1428
1429         return ret;
1430 }
1431
1432 static int do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
1433 {
1434         int ret;
1435
1436         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1437                 return -EPERM;
1438
1439         switch (cmd) {
1440         case ARPT_SO_GET_INFO:
1441                 ret = get_info(sock_net(sk), user, len);
1442                 break;
1443
1444         case ARPT_SO_GET_ENTRIES:
1445 #ifdef CONFIG_COMPAT
1446                 if (in_compat_syscall())
1447                         ret = compat_get_entries(sock_net(sk), user, len);
1448                 else
1449 #endif
1450                         ret = get_entries(sock_net(sk), user, len);
1451                 break;
1452
1453         case ARPT_SO_GET_REVISION_TARGET: {
1454                 struct xt_get_revision rev;
1455
1456                 if (*len != sizeof(rev)) {
1457                         ret = -EINVAL;
1458                         break;
1459                 }
1460                 if (copy_from_user(&rev, user, sizeof(rev)) != 0) {
1461                         ret = -EFAULT;
1462                         break;
1463                 }
1464                 rev.name[sizeof(rev.name)-1] = 0;
1465
1466                 try_then_request_module(xt_find_revision(NFPROTO_ARP, rev.name,
1467                                                          rev.revision, 1, &ret),
1468                                         "arpt_%s", rev.name);
1469                 break;
1470         }
1471
1472         default:
1473                 ret = -EINVAL;
1474         }
1475
1476         return ret;
1477 }
1478
1479 static void __arpt_unregister_table(struct net *net, struct xt_table *table)
1480 {
1481         struct xt_table_info *private;
1482         void *loc_cpu_entry;
1483         struct module *table_owner = table->me;
1484         struct arpt_entry *iter;
1485
1486         private = xt_unregister_table(table);
1487
1488         /* Decrease module usage counts and free resources */
1489         loc_cpu_entry = private->entries;
1490         xt_entry_foreach(iter, loc_cpu_entry, private->size)
1491                 cleanup_entry(iter, net);
1492         if (private->number > private->initial_entries)
1493                 module_put(table_owner);
1494         xt_free_table_info(private);
1495 }
1496
1497 int arpt_register_table(struct net *net,
1498                         const struct xt_table *table,
1499                         const struct arpt_replace *repl,
1500                         const struct nf_hook_ops *ops,
1501                         struct xt_table **res)
1502 {
1503         int ret;
1504         struct xt_table_info *newinfo;
1505         struct xt_table_info bootstrap = {0};
1506         void *loc_cpu_entry;
1507         struct xt_table *new_table;
1508
1509         newinfo = xt_alloc_table_info(repl->size);
1510         if (!newinfo)
1511                 return -ENOMEM;
1512
1513         loc_cpu_entry = newinfo->entries;
1514         memcpy(loc_cpu_entry, repl->entries, repl->size);
1515
1516         ret = translate_table(net, newinfo, loc_cpu_entry, repl);
1517         if (ret != 0)
1518                 goto out_free;
1519
1520         new_table = xt_register_table(net, table, &bootstrap, newinfo);
1521         if (IS_ERR(new_table)) {
1522                 ret = PTR_ERR(new_table);
1523                 goto out_free;
1524         }
1525
1526         /* set res now, will see skbs right after nf_register_net_hooks */
1527         WRITE_ONCE(*res, new_table);
1528
1529         ret = nf_register_net_hooks(net, ops, hweight32(table->valid_hooks));
1530         if (ret != 0) {
1531                 __arpt_unregister_table(net, new_table);
1532                 *res = NULL;
1533         }
1534
1535         return ret;
1536
1537 out_free:
1538         xt_free_table_info(newinfo);
1539         return ret;
1540 }
1541
1542 void arpt_unregister_table(struct net *net, struct xt_table *table,
1543                            const struct nf_hook_ops *ops)
1544 {
1545         nf_unregister_net_hooks(net, ops, hweight32(table->valid_hooks));
1546         __arpt_unregister_table(net, table);
1547 }
1548
1549 /* The built-in targets: standard (NULL) and error. */
1550 static struct xt_target arpt_builtin_tg[] __read_mostly = {
1551         {
1552                 .name             = XT_STANDARD_TARGET,
1553                 .targetsize       = sizeof(int),
1554                 .family           = NFPROTO_ARP,
1555 #ifdef CONFIG_COMPAT
1556                 .compatsize       = sizeof(compat_int_t),
1557                 .compat_from_user = compat_standard_from_user,
1558                 .compat_to_user   = compat_standard_to_user,
1559 #endif
1560         },
1561         {
1562                 .name             = XT_ERROR_TARGET,
1563                 .target           = arpt_error,
1564                 .targetsize       = XT_FUNCTION_MAXNAMELEN,
1565                 .family           = NFPROTO_ARP,
1566         },
1567 };
1568
1569 static struct nf_sockopt_ops arpt_sockopts = {
1570         .pf             = PF_INET,
1571         .set_optmin     = ARPT_BASE_CTL,
1572         .set_optmax     = ARPT_SO_SET_MAX+1,
1573         .set            = do_arpt_set_ctl,
1574         .get_optmin     = ARPT_BASE_CTL,
1575         .get_optmax     = ARPT_SO_GET_MAX+1,
1576         .get            = do_arpt_get_ctl,
1577         .owner          = THIS_MODULE,
1578 };
1579
1580 static int __net_init arp_tables_net_init(struct net *net)
1581 {
1582         return xt_proto_init(net, NFPROTO_ARP);
1583 }
1584
1585 static void __net_exit arp_tables_net_exit(struct net *net)
1586 {
1587         xt_proto_fini(net, NFPROTO_ARP);
1588 }
1589
1590 static struct pernet_operations arp_tables_net_ops = {
1591         .init = arp_tables_net_init,
1592         .exit = arp_tables_net_exit,
1593 };
1594
1595 static int __init arp_tables_init(void)
1596 {
1597         int ret;
1598
1599         ret = register_pernet_subsys(&arp_tables_net_ops);
1600         if (ret < 0)
1601                 goto err1;
1602
1603         /* No one else will be downing sem now, so we won't sleep */
1604         ret = xt_register_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1605         if (ret < 0)
1606                 goto err2;
1607
1608         /* Register setsockopt */
1609         ret = nf_register_sockopt(&arpt_sockopts);
1610         if (ret < 0)
1611                 goto err4;
1612
1613         return 0;
1614
1615 err4:
1616         xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1617 err2:
1618         unregister_pernet_subsys(&arp_tables_net_ops);
1619 err1:
1620         return ret;
1621 }
1622
1623 static void __exit arp_tables_fini(void)
1624 {
1625         nf_unregister_sockopt(&arpt_sockopts);
1626         xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1627         unregister_pernet_subsys(&arp_tables_net_ops);
1628 }
1629
1630 EXPORT_SYMBOL(arpt_register_table);
1631 EXPORT_SYMBOL(arpt_unregister_table);
1632 EXPORT_SYMBOL(arpt_do_table);
1633
1634 module_init(arp_tables_init);
1635 module_exit(arp_tables_fini);