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 = READ_ONCE(table->private); /* Address dependency. */
 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 inline int check_target(struct arpt_entry *e, const char *name)
 388 {
 389         struct xt_entry_target *t = arpt_get_target(e);
 390         struct xt_tgchk_param par = {
 391                 .table     = name,
 392                 .entryinfo = e,
 393                 .target    = t->u.kernel.target,
 394                 .targinfo  = t->data,
 395                 .hook_mask = e->comefrom,
 396                 .family    = NFPROTO_ARP,
 397         };
 398
 399         return xt_check_target(&par, t->u.target_size - sizeof(*t), 0, false);
 400 }
 401
 402 static inline int
 403 find_check_entry(struct arpt_entry *e, const char *name, unsigned int size,
 404                  struct xt_percpu_counter_alloc_state *alloc_state)
 405 {
 406         struct xt_entry_target *t;
 407         struct xt_target *target;
 408         int ret;
 409
 410         if (!xt_percpu_counter_alloc(alloc_state, &e->counters))
 411                 return -ENOMEM;
 412
 413         t = arpt_get_target(e);
 414         target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
 415                                         t->u.user.revision);
 416         if (IS_ERR(target)) {
 417                 ret = PTR_ERR(target);
 418                 goto out;
 419         }
 420         t->u.kernel.target = target;
 421
 422         ret = check_target(e, name);
 423         if (ret)
 424                 goto err;
 425         return 0;
 426 err:
 427         module_put(t->u.kernel.target->me);
 428 out:
 429         xt_percpu_counter_free(&e->counters);
 430
 431         return ret;
 432 }
 433
 434 static bool check_underflow(const struct arpt_entry *e)
 435 {
 436         const struct xt_entry_target *t;
 437         unsigned int verdict;
 438
 439         if (!unconditional(e))
 440                 return false;
 441         t = arpt_get_target_c(e);
 442         if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
 443                 return false;
 444         verdict = ((struct xt_standard_target *)t)->verdict;
 445         verdict = -verdict - 1;
 446         return verdict == NF_DROP || verdict == NF_ACCEPT;
 447 }
 448
 449 static inline int check_entry_size_and_hooks(struct arpt_entry *e,
 450                                              struct xt_table_info *newinfo,
 451                                              const unsigned char *base,
 452                                              const unsigned char *limit,
 453                                              const unsigned int *hook_entries,
 454                                              const unsigned int *underflows,
 455                                              unsigned int valid_hooks)
 456 {
 457         unsigned int h;
 458         int err;
 459
 460         if ((unsigned long)e % __alignof__(struct arpt_entry) != 0 ||
 461             (unsigned char *)e + sizeof(struct arpt_entry) >= limit ||
 462             (unsigned char *)e + e->next_offset > limit)
 463                 return -EINVAL;
 464
 465         if (e->next_offset
 466             < sizeof(struct arpt_entry) + sizeof(struct xt_entry_target))
 467                 return -EINVAL;
 468
 469         if (!arp_checkentry(&e->arp))
 470                 return -EINVAL;
 471
 472         err = xt_check_entry_offsets(e, e->elems, e->target_offset,
 473                                      e->next_offset);
 474         if (err)
 475                 return err;
 476
 477         /* Check hooks & underflows */
 478         for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
 479                 if (!(valid_hooks & (1 << h)))
 480                         continue;
 481                 if ((unsigned char *)e - base == hook_entries[h])
 482                         newinfo->hook_entry[h] = hook_entries[h];
 483                 if ((unsigned char *)e - base == underflows[h]) {
 484                         if (!check_underflow(e))
 485                                 return -EINVAL;
 486
 487                         newinfo->underflow[h] = underflows[h];
 488                 }
 489         }
 490
 491         /* Clear counters and comefrom */
 492         e->counters = ((struct xt_counters) { 0, 0 });
 493         e->comefrom = 0;
 494         return 0;
 495 }
 496
 497 static inline void cleanup_entry(struct arpt_entry *e)
 498 {
 499         struct xt_tgdtor_param par;
 500         struct xt_entry_target *t;
 501
 502         t = arpt_get_target(e);
 503         par.target   = t->u.kernel.target;
 504         par.targinfo = t->data;
 505         par.family   = NFPROTO_ARP;
 506         if (par.target->destroy != NULL)
 507                 par.target->destroy(&par);
 508         module_put(par.target->me);
 509         xt_percpu_counter_free(&e->counters);
 510 }
 511
 512 /* Checks and translates the user-supplied table segment (held in
 513  * newinfo).
 514  */
 515 static int translate_table(struct xt_table_info *newinfo, void *entry0,
 516                            const struct arpt_replace *repl)
 517 {
 518         struct xt_percpu_counter_alloc_state alloc_state = { 0 };
 519         struct arpt_entry *iter;
 520         unsigned int *offsets;
 521         unsigned int i;
 522         int ret = 0;
 523
 524         newinfo->size = repl->size;
 525         newinfo->number = repl->num_entries;
 526
 527         /* Init all hooks to impossible value. */
 528         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
 529                 newinfo->hook_entry[i] = 0xFFFFFFFF;
 530                 newinfo->underflow[i] = 0xFFFFFFFF;
 531         }
 532
 533         offsets = xt_alloc_entry_offsets(newinfo->number);
 534         if (!offsets)
 535                 return -ENOMEM;
 536         i = 0;
 537
 538         /* Walk through entries, checking offsets. */
 539         xt_entry_foreach(iter, entry0, newinfo->size) {
 540                 ret = check_entry_size_and_hooks(iter, newinfo, entry0,
 541                                                  entry0 + repl->size,
 542                                                  repl->hook_entry,
 543                                                  repl->underflow,
 544                                                  repl->valid_hooks);
 545                 if (ret != 0)
 546                         goto out_free;
 547                 if (i < repl->num_entries)
 548                         offsets[i] = (void *)iter - entry0;
 549                 ++i;
 550                 if (strcmp(arpt_get_target(iter)->u.user.name,
 551                     XT_ERROR_TARGET) == 0)
 552                         ++newinfo->stacksize;
 553         }
 554
 555         ret = -EINVAL;
 556         if (i != repl->num_entries)
 557                 goto out_free;
 558
 559         ret = xt_check_table_hooks(newinfo, repl->valid_hooks);
 560         if (ret)
 561                 goto out_free;
 562
 563         if (!mark_source_chains(newinfo, repl->valid_hooks, entry0, offsets)) {
 564                 ret = -ELOOP;
 565                 goto out_free;
 566         }
 567         kvfree(offsets);
 568
 569         /* Finally, each sanity check must pass */
 570         i = 0;
 571         xt_entry_foreach(iter, entry0, newinfo->size) {
 572                 ret = find_check_entry(iter, repl->name, repl->size,
 573                                        &alloc_state);
 574                 if (ret != 0)
 575                         break;
 576                 ++i;
 577         }
 578
 579         if (ret != 0) {
 580                 xt_entry_foreach(iter, entry0, newinfo->size) {
 581                         if (i-- == 0)
 582                                 break;
 583                         cleanup_entry(iter);
 584                 }
 585                 return ret;
 586         }
 587
 588         return ret;
 589  out_free:
 590         kvfree(offsets);
 591         return ret;
 592 }
 593
 594 static void get_counters(const struct xt_table_info *t,
 595                          struct xt_counters counters[])
 596 {
 597         struct arpt_entry *iter;
 598         unsigned int cpu;
 599         unsigned int i;
 600
 601         for_each_possible_cpu(cpu) {
 602                 seqcount_t *s = &per_cpu(xt_recseq, cpu);
 603
 604                 i = 0;
 605                 xt_entry_foreach(iter, t->entries, t->size) {
 606                         struct xt_counters *tmp;
 607                         u64 bcnt, pcnt;
 608                         unsigned int start;
 609
 610                         tmp = xt_get_per_cpu_counter(&iter->counters, cpu);
 611                         do {
 612                                 start = read_seqcount_begin(s);
 613                                 bcnt = tmp->bcnt;
 614                                 pcnt = tmp->pcnt;
 615                         } while (read_seqcount_retry(s, start));
 616
 617                         ADD_COUNTER(counters[i], bcnt, pcnt);
 618                         ++i;
 619                         cond_resched();
 620                 }
 621         }
 622 }
 623
 624 static void get_old_counters(const struct xt_table_info *t,
 625                              struct xt_counters counters[])
 626 {
 627         struct arpt_entry *iter;
 628         unsigned int cpu, i;
 629
 630         for_each_possible_cpu(cpu) {
 631                 i = 0;
 632                 xt_entry_foreach(iter, t->entries, t->size) {
 633                         struct xt_counters *tmp;
 634
 635                         tmp = xt_get_per_cpu_counter(&iter->counters, cpu);
 636                         ADD_COUNTER(counters[i], tmp->bcnt, tmp->pcnt);
 637                         ++i;
 638                 }
 639                 cond_resched();
 640         }
 641 }
 642
 643 static struct xt_counters *alloc_counters(const struct xt_table *table)
 644 {
 645         unsigned int countersize;
 646         struct xt_counters *counters;
 647         const struct xt_table_info *private = table->private;
 648
 649         /* We need atomic snapshot of counters: rest doesn't change
 650          * (other than comefrom, which userspace doesn't care
 651          * about).
 652          */
 653         countersize = sizeof(struct xt_counters) * private->number;
 654         counters = vzalloc(countersize);
 655
 656         if (counters == NULL)
 657                 return ERR_PTR(-ENOMEM);
 658
 659         get_counters(private, counters);
 660
 661         return counters;
 662 }
 663
 664 static int copy_entries_to_user(unsigned int total_size,
 665                                 const struct xt_table *table,
 666                                 void __user *userptr)
 667 {
 668         unsigned int off, num;
 669         const struct arpt_entry *e;
 670         struct xt_counters *counters;
 671         struct xt_table_info *private = table->private;
 672         int ret = 0;
 673         void *loc_cpu_entry;
 674
 675         counters = alloc_counters(table);
 676         if (IS_ERR(counters))
 677                 return PTR_ERR(counters);
 678
 679         loc_cpu_entry = private->entries;
 680
 681         /* FIXME: use iterator macros --RR */
 682         /* ... then go back and fix counters and names */
 683         for (off = 0, num = 0; off < total_size; off += e->next_offset, num++){
 684                 const struct xt_entry_target *t;
 685
 686                 e = loc_cpu_entry + off;
 687                 if (copy_to_user(userptr + off, e, sizeof(*e))) {
 688                         ret = -EFAULT;
 689                         goto free_counters;
 690                 }
 691                 if (copy_to_user(userptr + off
 692                                  + offsetof(struct arpt_entry, counters),
 693                                  &counters[num],
 694                                  sizeof(counters[num])) != 0) {
 695                         ret = -EFAULT;
 696                         goto free_counters;
 697                 }
 698
 699                 t = arpt_get_target_c(e);
 700                 if (xt_target_to_user(t, userptr + off + e->target_offset)) {
 701                         ret = -EFAULT;
 702                         goto free_counters;
 703                 }
 704         }
 705
 706  free_counters:
 707         vfree(counters);
 708         return ret;
 709 }
 710
 711 #ifdef CONFIG_COMPAT
 712 static void compat_standard_from_user(void *dst, const void *src)
 713 {
 714         int v = *(compat_int_t *)src;
 715
 716         if (v > 0)
 717                 v += xt_compat_calc_jump(NFPROTO_ARP, v);
 718         memcpy(dst, &v, sizeof(v));
 719 }
 720
 721 static int compat_standard_to_user(void __user *dst, const void *src)
 722 {
 723         compat_int_t cv = *(int *)src;
 724
 725         if (cv > 0)
 726                 cv -= xt_compat_calc_jump(NFPROTO_ARP, cv);
 727         return copy_to_user(dst, &cv, sizeof(cv)) ? -EFAULT : 0;
 728 }
 729
 730 static int compat_calc_entry(const struct arpt_entry *e,
 731                              const struct xt_table_info *info,
 732                              const void *base, struct xt_table_info *newinfo)
 733 {
 734         const struct xt_entry_target *t;
 735         unsigned int entry_offset;
 736         int off, i, ret;
 737
 738         off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
 739         entry_offset = (void *)e - base;
 740
 741         t = arpt_get_target_c(e);
 742         off += xt_compat_target_offset(t->u.kernel.target);
 743         newinfo->size -= off;
 744         ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
 745         if (ret)
 746                 return ret;
 747
 748         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
 749                 if (info->hook_entry[i] &&
 750                     (e < (struct arpt_entry *)(base + info->hook_entry[i])))
 751                         newinfo->hook_entry[i] -= off;
 752                 if (info->underflow[i] &&
 753                     (e < (struct arpt_entry *)(base + info->underflow[i])))
 754                         newinfo->underflow[i] -= off;
 755         }
 756         return 0;
 757 }
 758
 759 static int compat_table_info(const struct xt_table_info *info,
 760                              struct xt_table_info *newinfo)
 761 {
 762         struct arpt_entry *iter;
 763         const void *loc_cpu_entry;
 764         int ret;
 765
 766         if (!newinfo || !info)
 767                 return -EINVAL;
 768
 769         /* we dont care about newinfo->entries */
 770         memcpy(newinfo, info, offsetof(struct xt_table_info, entries));
 771         newinfo->initial_entries = 0;
 772         loc_cpu_entry = info->entries;
 773         ret = xt_compat_init_offsets(NFPROTO_ARP, info->number);
 774         if (ret)
 775                 return ret;
 776         xt_entry_foreach(iter, loc_cpu_entry, info->size) {
 777                 ret = compat_calc_entry(iter, info, loc_cpu_entry, newinfo);
 778                 if (ret != 0)
 779                         return ret;
 780         }
 781         return 0;
 782 }
 783 #endif
 784
 785 static int get_info(struct net *net, void __user *user,
 786                     const int *len, int compat)
 787 {
 788         char name[XT_TABLE_MAXNAMELEN];
 789         struct xt_table *t;
 790         int ret;
 791
 792         if (*len != sizeof(struct arpt_getinfo))
 793                 return -EINVAL;
 794
 795         if (copy_from_user(name, user, sizeof(name)) != 0)
 796                 return -EFAULT;
 797
 798         name[XT_TABLE_MAXNAMELEN-1] = '\0';
 799 #ifdef CONFIG_COMPAT
 800         if (compat)
 801                 xt_compat_lock(NFPROTO_ARP);
 802 #endif
 803         t = xt_request_find_table_lock(net, NFPROTO_ARP, name);
 804         if (!IS_ERR(t)) {
 805                 struct arpt_getinfo info;
 806                 const struct xt_table_info *private = t->private;
 807 #ifdef CONFIG_COMPAT
 808                 struct xt_table_info tmp;
 809
 810                 if (compat) {
 811                         ret = compat_table_info(private, &tmp);
 812                         xt_compat_flush_offsets(NFPROTO_ARP);
 813                         private = &tmp;
 814                 }
 815 #endif
 816                 memset(&info, 0, sizeof(info));
 817                 info.valid_hooks = t->valid_hooks;
 818                 memcpy(info.hook_entry, private->hook_entry,
 819                        sizeof(info.hook_entry));
 820                 memcpy(info.underflow, private->underflow,
 821                        sizeof(info.underflow));
 822                 info.num_entries = private->number;
 823                 info.size = private->size;
 824                 strcpy(info.name, name);
 825
 826                 if (copy_to_user(user, &info, *len) != 0)
 827                         ret = -EFAULT;
 828                 else
 829                         ret = 0;
 830                 xt_table_unlock(t);
 831                 module_put(t->me);
 832         } else
 833                 ret = PTR_ERR(t);
 834 #ifdef CONFIG_COMPAT
 835         if (compat)
 836                 xt_compat_unlock(NFPROTO_ARP);
 837 #endif
 838         return ret;
 839 }
 840
 841 static int get_entries(struct net *net, struct arpt_get_entries __user *uptr,
 842                        const int *len)
 843 {
 844         int ret;
 845         struct arpt_get_entries get;
 846         struct xt_table *t;
 847
 848         if (*len < sizeof(get))
 849                 return -EINVAL;
 850         if (copy_from_user(&get, uptr, sizeof(get)) != 0)
 851                 return -EFAULT;
 852         if (*len != sizeof(struct arpt_get_entries) + get.size)
 853                 return -EINVAL;
 854
 855         get.name[sizeof(get.name) - 1] = '\0';
 856
 857         t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
 858         if (!IS_ERR(t)) {
 859                 const struct xt_table_info *private = t->private;
 860
 861                 if (get.size == private->size)
 862                         ret = copy_entries_to_user(private->size,
 863                                                    t, uptr->entrytable);
 864                 else
 865                         ret = -EAGAIN;
 866
 867                 module_put(t->me);
 868                 xt_table_unlock(t);
 869         } else
 870                 ret = PTR_ERR(t);
 871
 872         return ret;
 873 }
 874
 875 static int __do_replace(struct net *net, const char *name,
 876                         unsigned int valid_hooks,
 877                         struct xt_table_info *newinfo,
 878                         unsigned int num_counters,
 879                         void __user *counters_ptr)
 880 {
 881         int ret;
 882         struct xt_table *t;
 883         struct xt_table_info *oldinfo;
 884         struct xt_counters *counters;
 885         void *loc_cpu_old_entry;
 886         struct arpt_entry *iter;
 887
 888         ret = 0;
 889         counters = xt_counters_alloc(num_counters);
 890         if (!counters) {
 891                 ret = -ENOMEM;
 892                 goto out;
 893         }
 894
 895         t = xt_request_find_table_lock(net, NFPROTO_ARP, name);
 896         if (IS_ERR(t)) {
 897                 ret = PTR_ERR(t);
 898                 goto free_newinfo_counters_untrans;
 899         }
 900
 901         /* You lied! */
 902         if (valid_hooks != t->valid_hooks) {
 903                 ret = -EINVAL;
 904                 goto put_module;
 905         }
 906
 907         oldinfo = xt_replace_table(t, num_counters, newinfo, &ret);
 908         if (!oldinfo)
 909                 goto put_module;
 910
 911         /* Update module usage count based on number of rules */
 912         if ((oldinfo->number > oldinfo->initial_entries) ||
 913             (newinfo->number <= oldinfo->initial_entries))
 914                 module_put(t->me);
 915         if ((oldinfo->number > oldinfo->initial_entries) &&
 916             (newinfo->number <= oldinfo->initial_entries))
 917                 module_put(t->me);
 918
 919         xt_table_unlock(t);
 920
 921         get_old_counters(oldinfo, counters);
 922
 923         /* Decrease module usage counts and free resource */
 924         loc_cpu_old_entry = oldinfo->entries;
 925         xt_entry_foreach(iter, loc_cpu_old_entry, oldinfo->size)
 926                 cleanup_entry(iter);
 927
 928         xt_free_table_info(oldinfo);
 929         if (copy_to_user(counters_ptr, counters,
 930                          sizeof(struct xt_counters) * num_counters) != 0) {
 931                 /* Silent error, can't fail, new table is already in place */
 932                 net_warn_ratelimited("arptables: counters copy to user failed while replacing table\n");
 933         }
 934         vfree(counters);
 935         return ret;
 936
 937  put_module:
 938         module_put(t->me);
 939         xt_table_unlock(t);
 940  free_newinfo_counters_untrans:
 941         vfree(counters);
 942  out:
 943         return ret;
 944 }
 945
 946 static int do_replace(struct net *net, const void __user *user,
 947                       unsigned int len)
 948 {
 949         int ret;
 950         struct arpt_replace tmp;
 951         struct xt_table_info *newinfo;
 952         void *loc_cpu_entry;
 953         struct arpt_entry *iter;
 954
 955         if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
 956                 return -EFAULT;
 957
 958         /* overflow check */
 959         if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
 960                 return -ENOMEM;
 961         if (tmp.num_counters == 0)
 962                 return -EINVAL;
 963
 964         tmp.name[sizeof(tmp.name)-1] = 0;
 965
 966         newinfo = xt_alloc_table_info(tmp.size);
 967         if (!newinfo)
 968                 return -ENOMEM;
 969
 970         loc_cpu_entry = newinfo->entries;
 971         if (copy_from_user(loc_cpu_entry, user + sizeof(tmp),
 972                            tmp.size) != 0) {
 973                 ret = -EFAULT;
 974                 goto free_newinfo;
 975         }
 976
 977         ret = translate_table(newinfo, loc_cpu_entry, &tmp);
 978         if (ret != 0)
 979                 goto free_newinfo;
 980
 981         ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
 982                            tmp.num_counters, tmp.counters);
 983         if (ret)
 984                 goto free_newinfo_untrans;
 985         return 0;
 986
 987  free_newinfo_untrans:
 988         xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
 989                 cleanup_entry(iter);
 990  free_newinfo:
 991         xt_free_table_info(newinfo);
 992         return ret;
 993 }
 994
 995 static int do_add_counters(struct net *net, const void __user *user,
 996                            unsigned int len, int compat)
 997 {
 998         unsigned int i;
 999         struct xt_counters_info tmp;
1000         struct xt_counters *paddc;
1001         struct xt_table *t;
1002         const struct xt_table_info *private;
1003         int ret = 0;
1004         struct arpt_entry *iter;
1005         unsigned int addend;
1006
1007         paddc = xt_copy_counters_from_user(user, len, &tmp, compat);
1008         if (IS_ERR(paddc))
1009                 return PTR_ERR(paddc);
1010
1011         t = xt_find_table_lock(net, NFPROTO_ARP, tmp.name);
1012         if (IS_ERR(t)) {
1013                 ret = PTR_ERR(t);
1014                 goto free;
1015         }
1016
1017         local_bh_disable();
1018         private = t->private;
1019         if (private->number != tmp.num_counters) {
1020                 ret = -EINVAL;
1021                 goto unlock_up_free;
1022         }
1023
1024         i = 0;
1025
1026         addend = xt_write_recseq_begin();
1027         xt_entry_foreach(iter,  private->entries, private->size) {
1028                 struct xt_counters *tmp;
1029
1030                 tmp = xt_get_this_cpu_counter(&iter->counters);
1031                 ADD_COUNTER(*tmp, paddc[i].bcnt, paddc[i].pcnt);
1032                 ++i;
1033         }
1034         xt_write_recseq_end(addend);
1035  unlock_up_free:
1036         local_bh_enable();
1037         xt_table_unlock(t);
1038         module_put(t->me);
1039  free:
1040         vfree(paddc);
1041
1042         return ret;
1043 }
1044
1045 #ifdef CONFIG_COMPAT
1046 struct compat_arpt_replace {
1047         char                            name[XT_TABLE_MAXNAMELEN];
1048         u32                             valid_hooks;
1049         u32                             num_entries;
1050         u32                             size;
1051         u32                             hook_entry[NF_ARP_NUMHOOKS];
1052         u32                             underflow[NF_ARP_NUMHOOKS];
1053         u32                             num_counters;
1054         compat_uptr_t                   counters;
1055         struct compat_arpt_entry        entries[0];
1056 };
1057
1058 static inline void compat_release_entry(struct compat_arpt_entry *e)
1059 {
1060         struct xt_entry_target *t;
1061
1062         t = compat_arpt_get_target(e);
1063         module_put(t->u.kernel.target->me);
1064 }
1065
1066 static int
1067 check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
1068                                   struct xt_table_info *newinfo,
1069                                   unsigned int *size,
1070                                   const unsigned char *base,
1071                                   const unsigned char *limit)
1072 {
1073         struct xt_entry_target *t;
1074         struct xt_target *target;
1075         unsigned int entry_offset;
1076         int ret, off;
1077
1078         if ((unsigned long)e % __alignof__(struct compat_arpt_entry) != 0 ||
1079             (unsigned char *)e + sizeof(struct compat_arpt_entry) >= limit ||
1080             (unsigned char *)e + e->next_offset > limit)
1081                 return -EINVAL;
1082
1083         if (e->next_offset < sizeof(struct compat_arpt_entry) +
1084                              sizeof(struct compat_xt_entry_target))
1085                 return -EINVAL;
1086
1087         if (!arp_checkentry(&e->arp))
1088                 return -EINVAL;
1089
1090         ret = xt_compat_check_entry_offsets(e, e->elems, e->target_offset,
1091                                             e->next_offset);
1092         if (ret)
1093                 return ret;
1094
1095         off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1096         entry_offset = (void *)e - (void *)base;
1097
1098         t = compat_arpt_get_target(e);
1099         target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
1100                                         t->u.user.revision);
1101         if (IS_ERR(target)) {
1102                 ret = PTR_ERR(target);
1103                 goto out;
1104         }
1105         t->u.kernel.target = target;
1106
1107         off += xt_compat_target_offset(target);
1108         *size += off;
1109         ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
1110         if (ret)
1111                 goto release_target;
1112
1113         return 0;
1114
1115 release_target:
1116         module_put(t->u.kernel.target->me);
1117 out:
1118         return ret;
1119 }
1120
1121 static void
1122 compat_copy_entry_from_user(struct compat_arpt_entry *e, void **dstptr,
1123                             unsigned int *size,
1124                             struct xt_table_info *newinfo, unsigned char *base)
1125 {
1126         struct xt_entry_target *t;
1127         struct arpt_entry *de;
1128         unsigned int origsize;
1129         int h;
1130
1131         origsize = *size;
1132         de = *dstptr;
1133         memcpy(de, e, sizeof(struct arpt_entry));
1134         memcpy(&de->counters, &e->counters, sizeof(e->counters));
1135
1136         *dstptr += sizeof(struct arpt_entry);
1137         *size += sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1138
1139         de->target_offset = e->target_offset - (origsize - *size);
1140         t = compat_arpt_get_target(e);
1141         xt_compat_target_from_user(t, dstptr, size);
1142
1143         de->next_offset = e->next_offset - (origsize - *size);
1144         for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
1145                 if ((unsigned char *)de - base < newinfo->hook_entry[h])
1146                         newinfo->hook_entry[h] -= origsize - *size;
1147                 if ((unsigned char *)de - base < newinfo->underflow[h])
1148                         newinfo->underflow[h] -= origsize - *size;
1149         }
1150 }
1151
1152 static int translate_compat_table(struct xt_table_info **pinfo,
1153                                   void **pentry0,
1154                                   const struct compat_arpt_replace *compatr)
1155 {
1156         unsigned int i, j;
1157         struct xt_table_info *newinfo, *info;
1158         void *pos, *entry0, *entry1;
1159         struct compat_arpt_entry *iter0;
1160         struct arpt_replace repl;
1161         unsigned int size;
1162         int ret;
1163
1164         info = *pinfo;
1165         entry0 = *pentry0;
1166         size = compatr->size;
1167         info->number = compatr->num_entries;
1168
1169         j = 0;
1170         xt_compat_lock(NFPROTO_ARP);
1171         ret = xt_compat_init_offsets(NFPROTO_ARP, compatr->num_entries);
1172         if (ret)
1173                 goto out_unlock;
1174         /* Walk through entries, checking offsets. */
1175         xt_entry_foreach(iter0, entry0, compatr->size) {
1176                 ret = check_compat_entry_size_and_hooks(iter0, info, &size,
1177                                                         entry0,
1178                                                         entry0 + compatr->size);
1179                 if (ret != 0)
1180                         goto out_unlock;
1181                 ++j;
1182         }
1183
1184         ret = -EINVAL;
1185         if (j != compatr->num_entries)
1186                 goto out_unlock;
1187
1188         ret = -ENOMEM;
1189         newinfo = xt_alloc_table_info(size);
1190         if (!newinfo)
1191                 goto out_unlock;
1192
1193         newinfo->number = compatr->num_entries;
1194         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1195                 newinfo->hook_entry[i] = compatr->hook_entry[i];
1196                 newinfo->underflow[i] = compatr->underflow[i];
1197         }
1198         entry1 = newinfo->entries;
1199         pos = entry1;
1200         size = compatr->size;
1201         xt_entry_foreach(iter0, entry0, compatr->size)
1202                 compat_copy_entry_from_user(iter0, &pos, &size,
1203                                             newinfo, entry1);
1204
1205         /* all module references in entry0 are now gone */
1206
1207         xt_compat_flush_offsets(NFPROTO_ARP);
1208         xt_compat_unlock(NFPROTO_ARP);
1209
1210         memcpy(&repl, compatr, sizeof(*compatr));
1211
1212         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1213                 repl.hook_entry[i] = newinfo->hook_entry[i];
1214                 repl.underflow[i] = newinfo->underflow[i];
1215         }
1216
1217         repl.num_counters = 0;
1218         repl.counters = NULL;
1219         repl.size = newinfo->size;
1220         ret = translate_table(newinfo, entry1, &repl);
1221         if (ret)
1222                 goto free_newinfo;
1223
1224         *pinfo = newinfo;
1225         *pentry0 = entry1;
1226         xt_free_table_info(info);
1227         return 0;
1228
1229 free_newinfo:
1230         xt_free_table_info(newinfo);
1231         return ret;
1232 out_unlock:
1233         xt_compat_flush_offsets(NFPROTO_ARP);
1234         xt_compat_unlock(NFPROTO_ARP);
1235         xt_entry_foreach(iter0, entry0, compatr->size) {
1236                 if (j-- == 0)
1237                         break;
1238                 compat_release_entry(iter0);
1239         }
1240         return ret;
1241 }
1242
1243 static int compat_do_replace(struct net *net, void __user *user,
1244                              unsigned int len)
1245 {
1246         int ret;
1247         struct compat_arpt_replace tmp;
1248         struct xt_table_info *newinfo;
1249         void *loc_cpu_entry;
1250         struct arpt_entry *iter;
1251
1252         if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
1253                 return -EFAULT;
1254
1255         /* overflow check */
1256         if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
1257                 return -ENOMEM;
1258         if (tmp.num_counters == 0)
1259                 return -EINVAL;
1260
1261         tmp.name[sizeof(tmp.name)-1] = 0;
1262
1263         newinfo = xt_alloc_table_info(tmp.size);
1264         if (!newinfo)
1265                 return -ENOMEM;
1266
1267         loc_cpu_entry = newinfo->entries;
1268         if (copy_from_user(loc_cpu_entry, user + sizeof(tmp), tmp.size) != 0) {
1269                 ret = -EFAULT;
1270                 goto free_newinfo;
1271         }
1272
1273         ret = translate_compat_table(&newinfo, &loc_cpu_entry, &tmp);
1274         if (ret != 0)
1275                 goto free_newinfo;
1276
1277         ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
1278                            tmp.num_counters, compat_ptr(tmp.counters));
1279         if (ret)
1280                 goto free_newinfo_untrans;
1281         return 0;
1282
1283  free_newinfo_untrans:
1284         xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
1285                 cleanup_entry(iter);
1286  free_newinfo:
1287         xt_free_table_info(newinfo);
1288         return ret;
1289 }
1290
1291 static int compat_do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user,
1292                                   unsigned int len)
1293 {
1294         int ret;
1295
1296         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1297                 return -EPERM;
1298
1299         switch (cmd) {
1300         case ARPT_SO_SET_REPLACE:
1301                 ret = compat_do_replace(sock_net(sk), user, len);
1302                 break;
1303
1304         case ARPT_SO_SET_ADD_COUNTERS:
1305                 ret = do_add_counters(sock_net(sk), user, len, 1);
1306                 break;
1307
1308         default:
1309                 ret = -EINVAL;
1310         }
1311
1312         return ret;
1313 }
1314
1315 static int compat_copy_entry_to_user(struct arpt_entry *e, void __user **dstptr,
1316                                      compat_uint_t *size,
1317                                      struct xt_counters *counters,
1318                                      unsigned int i)
1319 {
1320         struct xt_entry_target *t;
1321         struct compat_arpt_entry __user *ce;
1322         u_int16_t target_offset, next_offset;
1323         compat_uint_t origsize;
1324         int ret;
1325
1326         origsize = *size;
1327         ce = *dstptr;
1328         if (copy_to_user(ce, e, sizeof(struct arpt_entry)) != 0 ||
1329             copy_to_user(&ce->counters, &counters[i],
1330             sizeof(counters[i])) != 0)
1331                 return -EFAULT;
1332
1333         *dstptr += sizeof(struct compat_arpt_entry);
1334         *size -= sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1335
1336         target_offset = e->target_offset - (origsize - *size);
1337
1338         t = arpt_get_target(e);
1339         ret = xt_compat_target_to_user(t, dstptr, size);
1340         if (ret)
1341                 return ret;
1342         next_offset = e->next_offset - (origsize - *size);
1343         if (put_user(target_offset, &ce->target_offset) != 0 ||
1344             put_user(next_offset, &ce->next_offset) != 0)
1345                 return -EFAULT;
1346         return 0;
1347 }
1348
1349 static int compat_copy_entries_to_user(unsigned int total_size,
1350                                        struct xt_table *table,
1351                                        void __user *userptr)
1352 {
1353         struct xt_counters *counters;
1354         const struct xt_table_info *private = table->private;
1355         void __user *pos;
1356         unsigned int size;
1357         int ret = 0;
1358         unsigned int i = 0;
1359         struct arpt_entry *iter;
1360
1361         counters = alloc_counters(table);
1362         if (IS_ERR(counters))
1363                 return PTR_ERR(counters);
1364
1365         pos = userptr;
1366         size = total_size;
1367         xt_entry_foreach(iter, private->entries, total_size) {
1368                 ret = compat_copy_entry_to_user(iter, &pos,
1369                                                 &size, counters, i++);
1370                 if (ret != 0)
1371                         break;
1372         }
1373         vfree(counters);
1374         return ret;
1375 }
1376
1377 struct compat_arpt_get_entries {
1378         char name[XT_TABLE_MAXNAMELEN];
1379         compat_uint_t size;
1380         struct compat_arpt_entry entrytable[0];
1381 };
1382
1383 static int compat_get_entries(struct net *net,
1384                               struct compat_arpt_get_entries __user *uptr,
1385                               int *len)
1386 {
1387         int ret;
1388         struct compat_arpt_get_entries get;
1389         struct xt_table *t;
1390
1391         if (*len < sizeof(get))
1392                 return -EINVAL;
1393         if (copy_from_user(&get, uptr, sizeof(get)) != 0)
1394                 return -EFAULT;
1395         if (*len != sizeof(struct compat_arpt_get_entries) + get.size)
1396                 return -EINVAL;
1397
1398         get.name[sizeof(get.name) - 1] = '\0';
1399
1400         xt_compat_lock(NFPROTO_ARP);
1401         t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
1402         if (!IS_ERR(t)) {
1403                 const struct xt_table_info *private = t->private;
1404                 struct xt_table_info info;
1405
1406                 ret = compat_table_info(private, &info);
1407                 if (!ret && get.size == info.size) {
1408                         ret = compat_copy_entries_to_user(private->size,
1409                                                           t, uptr->entrytable);
1410                 } else if (!ret)
1411                         ret = -EAGAIN;
1412
1413                 xt_compat_flush_offsets(NFPROTO_ARP);
1414                 module_put(t->me);
1415                 xt_table_unlock(t);
1416         } else
1417                 ret = PTR_ERR(t);
1418
1419         xt_compat_unlock(NFPROTO_ARP);
1420         return ret;
1421 }
1422
1423 static int do_arpt_get_ctl(struct sock *, int, void __user *, int *);
1424
1425 static int compat_do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user,
1426                                   int *len)
1427 {
1428         int ret;
1429
1430         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1431                 return -EPERM;
1432
1433         switch (cmd) {
1434         case ARPT_SO_GET_INFO:
1435                 ret = get_info(sock_net(sk), user, len, 1);
1436                 break;
1437         case ARPT_SO_GET_ENTRIES:
1438                 ret = compat_get_entries(sock_net(sk), user, len);
1439                 break;
1440         default:
1441                 ret = do_arpt_get_ctl(sk, cmd, user, len);
1442         }
1443         return ret;
1444 }
1445 #endif
1446
1447 static int do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
1448 {
1449         int ret;
1450
1451         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1452                 return -EPERM;
1453
1454         switch (cmd) {
1455         case ARPT_SO_SET_REPLACE:
1456                 ret = do_replace(sock_net(sk), user, len);
1457                 break;
1458
1459         case ARPT_SO_SET_ADD_COUNTERS:
1460                 ret = do_add_counters(sock_net(sk), user, len, 0);
1461                 break;
1462
1463         default:
1464                 ret = -EINVAL;
1465         }
1466
1467         return ret;
1468 }
1469
1470 static int do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
1471 {
1472         int ret;
1473
1474         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1475                 return -EPERM;
1476
1477         switch (cmd) {
1478         case ARPT_SO_GET_INFO:
1479                 ret = get_info(sock_net(sk), user, len, 0);
1480                 break;
1481
1482         case ARPT_SO_GET_ENTRIES:
1483                 ret = get_entries(sock_net(sk), user, len);
1484                 break;
1485
1486         case ARPT_SO_GET_REVISION_TARGET: {
1487                 struct xt_get_revision rev;
1488
1489                 if (*len != sizeof(rev)) {
1490                         ret = -EINVAL;
1491                         break;
1492                 }
1493                 if (copy_from_user(&rev, user, sizeof(rev)) != 0) {
1494                         ret = -EFAULT;
1495                         break;
1496                 }
1497                 rev.name[sizeof(rev.name)-1] = 0;
1498
1499                 try_then_request_module(xt_find_revision(NFPROTO_ARP, rev.name,
1500                                                          rev.revision, 1, &ret),
1501                                         "arpt_%s", rev.name);
1502                 break;
1503         }
1504
1505         default:
1506                 ret = -EINVAL;
1507         }
1508
1509         return ret;
1510 }
1511
1512 static void __arpt_unregister_table(struct xt_table *table)
1513 {
1514         struct xt_table_info *private;
1515         void *loc_cpu_entry;
1516         struct module *table_owner = table->me;
1517         struct arpt_entry *iter;
1518
1519         private = xt_unregister_table(table);
1520
1521         /* Decrease module usage counts and free resources */
1522         loc_cpu_entry = private->entries;
1523         xt_entry_foreach(iter, loc_cpu_entry, private->size)
1524                 cleanup_entry(iter);
1525         if (private->number > private->initial_entries)
1526                 module_put(table_owner);
1527         xt_free_table_info(private);
1528 }
1529
1530 int arpt_register_table(struct net *net,
1531                         const struct xt_table *table,
1532                         const struct arpt_replace *repl,
1533                         const struct nf_hook_ops *ops,
1534                         struct xt_table **res)
1535 {
1536         int ret;
1537         struct xt_table_info *newinfo;
1538         struct xt_table_info bootstrap = {0};
1539         void *loc_cpu_entry;
1540         struct xt_table *new_table;
1541
1542         newinfo = xt_alloc_table_info(repl->size);
1543         if (!newinfo)
1544                 return -ENOMEM;
1545
1546         loc_cpu_entry = newinfo->entries;
1547         memcpy(loc_cpu_entry, repl->entries, repl->size);
1548
1549         ret = translate_table(newinfo, loc_cpu_entry, repl);
1550         if (ret != 0)
1551                 goto out_free;
1552
1553         new_table = xt_register_table(net, table, &bootstrap, newinfo);
1554         if (IS_ERR(new_table)) {
1555                 ret = PTR_ERR(new_table);
1556                 goto out_free;
1557         }
1558
1559         /* set res now, will see skbs right after nf_register_net_hooks */
1560         WRITE_ONCE(*res, new_table);
1561
1562         ret = nf_register_net_hooks(net, ops, hweight32(table->valid_hooks));
1563         if (ret != 0) {
1564                 __arpt_unregister_table(new_table);
1565                 *res = NULL;
1566         }
1567
1568         return ret;
1569
1570 out_free:
1571         xt_free_table_info(newinfo);
1572         return ret;
1573 }
1574
1575 void arpt_unregister_table(struct net *net, struct xt_table *table,
1576                            const struct nf_hook_ops *ops)
1577 {
1578         nf_unregister_net_hooks(net, ops, hweight32(table->valid_hooks));
1579         __arpt_unregister_table(table);
1580 }
1581
1582 /* The built-in targets: standard (NULL) and error. */
1583 static struct xt_target arpt_builtin_tg[] __read_mostly = {
1584         {
1585                 .name             = XT_STANDARD_TARGET,
1586                 .targetsize       = sizeof(int),
1587                 .family           = NFPROTO_ARP,
1588 #ifdef CONFIG_COMPAT
1589                 .compatsize       = sizeof(compat_int_t),
1590                 .compat_from_user = compat_standard_from_user,
1591                 .compat_to_user   = compat_standard_to_user,
1592 #endif
1593         },
1594         {
1595                 .name             = XT_ERROR_TARGET,
1596                 .target           = arpt_error,
1597                 .targetsize       = XT_FUNCTION_MAXNAMELEN,
1598                 .family           = NFPROTO_ARP,
1599         },
1600 };
1601
1602 static struct nf_sockopt_ops arpt_sockopts = {
1603         .pf             = PF_INET,
1604         .set_optmin     = ARPT_BASE_CTL,
1605         .set_optmax     = ARPT_SO_SET_MAX+1,
1606         .set            = do_arpt_set_ctl,
1607 #ifdef CONFIG_COMPAT
1608         .compat_set     = compat_do_arpt_set_ctl,
1609 #endif
1610         .get_optmin     = ARPT_BASE_CTL,
1611         .get_optmax     = ARPT_SO_GET_MAX+1,
1612         .get            = do_arpt_get_ctl,
1613 #ifdef CONFIG_COMPAT
1614         .compat_get     = compat_do_arpt_get_ctl,
1615 #endif
1616         .owner          = THIS_MODULE,
1617 };
1618
1619 static int __net_init arp_tables_net_init(struct net *net)
1620 {
1621         return xt_proto_init(net, NFPROTO_ARP);
1622 }
1623
1624 static void __net_exit arp_tables_net_exit(struct net *net)
1625 {
1626         xt_proto_fini(net, NFPROTO_ARP);
1627 }
1628
1629 static struct pernet_operations arp_tables_net_ops = {
1630         .init = arp_tables_net_init,
1631         .exit = arp_tables_net_exit,
1632 };
1633
1634 static int __init arp_tables_init(void)
1635 {
1636         int ret;
1637
1638         ret = register_pernet_subsys(&arp_tables_net_ops);
1639         if (ret < 0)
1640                 goto err1;
1641
1642         /* No one else will be downing sem now, so we won't sleep */
1643         ret = xt_register_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1644         if (ret < 0)
1645                 goto err2;
1646
1647         /* Register setsockopt */
1648         ret = nf_register_sockopt(&arpt_sockopts);
1649         if (ret < 0)
1650                 goto err4;
1651
1652         return 0;
1653
1654 err4:
1655         xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1656 err2:
1657         unregister_pernet_subsys(&arp_tables_net_ops);
1658 err1:
1659         return ret;
1660 }
1661
1662 static void __exit arp_tables_fini(void)
1663 {
1664         nf_unregister_sockopt(&arpt_sockopts);
1665         xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1666         unregister_pernet_subsys(&arp_tables_net_ops);
1667 }
1668
1669 EXPORT_SYMBOL(arpt_register_table);
1670 EXPORT_SYMBOL(arpt_unregister_table);
1671 EXPORT_SYMBOL(arpt_do_table);
1672
1673 module_init(arp_tables_init);
1674 module_exit(arp_tables_fini);