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 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 = table->private;
 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 = table->private;
 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,
 791                     const int *len, int compat)
 792 {
 793         char name[XT_TABLE_MAXNAMELEN];
 794         struct xt_table *t;
 795         int ret;
 796
 797         if (*len != sizeof(struct arpt_getinfo))
 798                 return -EINVAL;
 799
 800         if (copy_from_user(name, user, sizeof(name)) != 0)
 801                 return -EFAULT;
 802
 803         name[XT_TABLE_MAXNAMELEN-1] = '\0';
 804 #ifdef CONFIG_COMPAT
 805         if (compat)
 806                 xt_compat_lock(NFPROTO_ARP);
 807 #endif
 808         t = xt_request_find_table_lock(net, NFPROTO_ARP, name);
 809         if (!IS_ERR(t)) {
 810                 struct arpt_getinfo info;
 811                 const struct xt_table_info *private = t->private;
 812 #ifdef CONFIG_COMPAT
 813                 struct xt_table_info tmp;
 814
 815                 if (compat) {
 816                         ret = compat_table_info(private, &tmp);
 817                         xt_compat_flush_offsets(NFPROTO_ARP);
 818                         private = &tmp;
 819                 }
 820 #endif
 821                 memset(&info, 0, sizeof(info));
 822                 info.valid_hooks = t->valid_hooks;
 823                 memcpy(info.hook_entry, private->hook_entry,
 824                        sizeof(info.hook_entry));
 825                 memcpy(info.underflow, private->underflow,
 826                        sizeof(info.underflow));
 827                 info.num_entries = private->number;
 828                 info.size = private->size;
 829                 strcpy(info.name, name);
 830
 831                 if (copy_to_user(user, &info, *len) != 0)
 832                         ret = -EFAULT;
 833                 else
 834                         ret = 0;
 835                 xt_table_unlock(t);
 836                 module_put(t->me);
 837         } else
 838                 ret = PTR_ERR(t);
 839 #ifdef CONFIG_COMPAT
 840         if (compat)
 841                 xt_compat_unlock(NFPROTO_ARP);
 842 #endif
 843         return ret;
 844 }
 845
 846 static int get_entries(struct net *net, struct arpt_get_entries __user *uptr,
 847                        const int *len)
 848 {
 849         int ret;
 850         struct arpt_get_entries get;
 851         struct xt_table *t;
 852
 853         if (*len < sizeof(get))
 854                 return -EINVAL;
 855         if (copy_from_user(&get, uptr, sizeof(get)) != 0)
 856                 return -EFAULT;
 857         if (*len != sizeof(struct arpt_get_entries) + get.size)
 858                 return -EINVAL;
 859
 860         get.name[sizeof(get.name) - 1] = '\0';
 861
 862         t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
 863         if (!IS_ERR(t)) {
 864                 const struct xt_table_info *private = t->private;
 865
 866                 if (get.size == private->size)
 867                         ret = copy_entries_to_user(private->size,
 868                                                    t, uptr->entrytable);
 869                 else
 870                         ret = -EAGAIN;
 871
 872                 module_put(t->me);
 873                 xt_table_unlock(t);
 874         } else
 875                 ret = PTR_ERR(t);
 876
 877         return ret;
 878 }
 879
 880 static int __do_replace(struct net *net, const char *name,
 881                         unsigned int valid_hooks,
 882                         struct xt_table_info *newinfo,
 883                         unsigned int num_counters,
 884                         void __user *counters_ptr)
 885 {
 886         int ret;
 887         struct xt_table *t;
 888         struct xt_table_info *oldinfo;
 889         struct xt_counters *counters;
 890         void *loc_cpu_old_entry;
 891         struct arpt_entry *iter;
 892
 893         ret = 0;
 894         counters = xt_counters_alloc(num_counters);
 895         if (!counters) {
 896                 ret = -ENOMEM;
 897                 goto out;
 898         }
 899
 900         t = xt_request_find_table_lock(net, NFPROTO_ARP, name);
 901         if (IS_ERR(t)) {
 902                 ret = PTR_ERR(t);
 903                 goto free_newinfo_counters_untrans;
 904         }
 905
 906         /* You lied! */
 907         if (valid_hooks != t->valid_hooks) {
 908                 ret = -EINVAL;
 909                 goto put_module;
 910         }
 911
 912         oldinfo = xt_replace_table(t, num_counters, newinfo, &ret);
 913         if (!oldinfo)
 914                 goto put_module;
 915
 916         /* Update module usage count based on number of rules */
 917         if ((oldinfo->number > oldinfo->initial_entries) ||
 918             (newinfo->number <= oldinfo->initial_entries))
 919                 module_put(t->me);
 920         if ((oldinfo->number > oldinfo->initial_entries) &&
 921             (newinfo->number <= oldinfo->initial_entries))
 922                 module_put(t->me);
 923
 924         xt_table_unlock(t);
 925
 926         get_old_counters(oldinfo, counters);
 927
 928         /* Decrease module usage counts and free resource */
 929         loc_cpu_old_entry = oldinfo->entries;
 930         xt_entry_foreach(iter, loc_cpu_old_entry, oldinfo->size)
 931                 cleanup_entry(iter, net);
 932
 933         xt_free_table_info(oldinfo);
 934         if (copy_to_user(counters_ptr, counters,
 935                          sizeof(struct xt_counters) * num_counters) != 0) {
 936                 /* Silent error, can't fail, new table is already in place */
 937                 net_warn_ratelimited("arptables: counters copy to user failed while replacing table\n");
 938         }
 939         vfree(counters);
 940         return ret;
 941
 942  put_module:
 943         module_put(t->me);
 944         xt_table_unlock(t);
 945  free_newinfo_counters_untrans:
 946         vfree(counters);
 947  out:
 948         return ret;
 949 }
 950
 951 static int do_replace(struct net *net, const void __user *user,
 952                       unsigned int len)
 953 {
 954         int ret;
 955         struct arpt_replace tmp;
 956         struct xt_table_info *newinfo;
 957         void *loc_cpu_entry;
 958         struct arpt_entry *iter;
 959
 960         if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
 961                 return -EFAULT;
 962
 963         /* overflow check */
 964         if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
 965                 return -ENOMEM;
 966         if (tmp.num_counters == 0)
 967                 return -EINVAL;
 968
 969         tmp.name[sizeof(tmp.name)-1] = 0;
 970
 971         newinfo = xt_alloc_table_info(tmp.size);
 972         if (!newinfo)
 973                 return -ENOMEM;
 974
 975         loc_cpu_entry = newinfo->entries;
 976         if (copy_from_user(loc_cpu_entry, user + sizeof(tmp),
 977                            tmp.size) != 0) {
 978                 ret = -EFAULT;
 979                 goto free_newinfo;
 980         }
 981
 982         ret = translate_table(net, newinfo, loc_cpu_entry, &tmp);
 983         if (ret != 0)
 984                 goto free_newinfo;
 985
 986         ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
 987                            tmp.num_counters, tmp.counters);
 988         if (ret)
 989                 goto free_newinfo_untrans;
 990         return 0;
 991
 992  free_newinfo_untrans:
 993         xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
 994                 cleanup_entry(iter, net);
 995  free_newinfo:
 996         xt_free_table_info(newinfo);
 997         return ret;
 998 }
 999
1000 static int do_add_counters(struct net *net, const void __user *user,
1001                            unsigned int len, int compat)
1002 {
1003         unsigned int i;
1004         struct xt_counters_info tmp;
1005         struct xt_counters *paddc;
1006         struct xt_table *t;
1007         const struct xt_table_info *private;
1008         int ret = 0;
1009         struct arpt_entry *iter;
1010         unsigned int addend;
1011
1012         paddc = xt_copy_counters_from_user(user, len, &tmp, compat);
1013         if (IS_ERR(paddc))
1014                 return PTR_ERR(paddc);
1015
1016         t = xt_find_table_lock(net, NFPROTO_ARP, tmp.name);
1017         if (IS_ERR(t)) {
1018                 ret = PTR_ERR(t);
1019                 goto free;
1020         }
1021
1022         local_bh_disable();
1023         private = t->private;
1024         if (private->number != tmp.num_counters) {
1025                 ret = -EINVAL;
1026                 goto unlock_up_free;
1027         }
1028
1029         i = 0;
1030
1031         addend = xt_write_recseq_begin();
1032         xt_entry_foreach(iter,  private->entries, private->size) {
1033                 struct xt_counters *tmp;
1034
1035                 tmp = xt_get_this_cpu_counter(&iter->counters);
1036                 ADD_COUNTER(*tmp, paddc[i].bcnt, paddc[i].pcnt);
1037                 ++i;
1038         }
1039         xt_write_recseq_end(addend);
1040  unlock_up_free:
1041         local_bh_enable();
1042         xt_table_unlock(t);
1043         module_put(t->me);
1044  free:
1045         vfree(paddc);
1046
1047         return ret;
1048 }
1049
1050 #ifdef CONFIG_COMPAT
1051 struct compat_arpt_replace {
1052         char                            name[XT_TABLE_MAXNAMELEN];
1053         u32                             valid_hooks;
1054         u32                             num_entries;
1055         u32                             size;
1056         u32                             hook_entry[NF_ARP_NUMHOOKS];
1057         u32                             underflow[NF_ARP_NUMHOOKS];
1058         u32                             num_counters;
1059         compat_uptr_t                   counters;
1060         struct compat_arpt_entry        entries[];
1061 };
1062
1063 static inline void compat_release_entry(struct compat_arpt_entry *e)
1064 {
1065         struct xt_entry_target *t;
1066
1067         t = compat_arpt_get_target(e);
1068         module_put(t->u.kernel.target->me);
1069 }
1070
1071 static int
1072 check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
1073                                   struct xt_table_info *newinfo,
1074                                   unsigned int *size,
1075                                   const unsigned char *base,
1076                                   const unsigned char *limit)
1077 {
1078         struct xt_entry_target *t;
1079         struct xt_target *target;
1080         unsigned int entry_offset;
1081         int ret, off;
1082
1083         if ((unsigned long)e % __alignof__(struct compat_arpt_entry) != 0 ||
1084             (unsigned char *)e + sizeof(struct compat_arpt_entry) >= limit ||
1085             (unsigned char *)e + e->next_offset > limit)
1086                 return -EINVAL;
1087
1088         if (e->next_offset < sizeof(struct compat_arpt_entry) +
1089                              sizeof(struct compat_xt_entry_target))
1090                 return -EINVAL;
1091
1092         if (!arp_checkentry(&e->arp))
1093                 return -EINVAL;
1094
1095         ret = xt_compat_check_entry_offsets(e, e->elems, e->target_offset,
1096                                             e->next_offset);
1097         if (ret)
1098                 return ret;
1099
1100         off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1101         entry_offset = (void *)e - (void *)base;
1102
1103         t = compat_arpt_get_target(e);
1104         target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
1105                                         t->u.user.revision);
1106         if (IS_ERR(target)) {
1107                 ret = PTR_ERR(target);
1108                 goto out;
1109         }
1110         t->u.kernel.target = target;
1111
1112         off += xt_compat_target_offset(target);
1113         *size += off;
1114         ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
1115         if (ret)
1116                 goto release_target;
1117
1118         return 0;
1119
1120 release_target:
1121         module_put(t->u.kernel.target->me);
1122 out:
1123         return ret;
1124 }
1125
1126 static void
1127 compat_copy_entry_from_user(struct compat_arpt_entry *e, void **dstptr,
1128                             unsigned int *size,
1129                             struct xt_table_info *newinfo, unsigned char *base)
1130 {
1131         struct xt_entry_target *t;
1132         struct arpt_entry *de;
1133         unsigned int origsize;
1134         int h;
1135
1136         origsize = *size;
1137         de = *dstptr;
1138         memcpy(de, e, sizeof(struct arpt_entry));
1139         memcpy(&de->counters, &e->counters, sizeof(e->counters));
1140
1141         *dstptr += sizeof(struct arpt_entry);
1142         *size += sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1143
1144         de->target_offset = e->target_offset - (origsize - *size);
1145         t = compat_arpt_get_target(e);
1146         xt_compat_target_from_user(t, dstptr, size);
1147
1148         de->next_offset = e->next_offset - (origsize - *size);
1149         for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
1150                 if ((unsigned char *)de - base < newinfo->hook_entry[h])
1151                         newinfo->hook_entry[h] -= origsize - *size;
1152                 if ((unsigned char *)de - base < newinfo->underflow[h])
1153                         newinfo->underflow[h] -= origsize - *size;
1154         }
1155 }
1156
1157 static int translate_compat_table(struct net *net,
1158                                   struct xt_table_info **pinfo,
1159                                   void **pentry0,
1160                                   const struct compat_arpt_replace *compatr)
1161 {
1162         unsigned int i, j;
1163         struct xt_table_info *newinfo, *info;
1164         void *pos, *entry0, *entry1;
1165         struct compat_arpt_entry *iter0;
1166         struct arpt_replace repl;
1167         unsigned int size;
1168         int ret;
1169
1170         info = *pinfo;
1171         entry0 = *pentry0;
1172         size = compatr->size;
1173         info->number = compatr->num_entries;
1174
1175         j = 0;
1176         xt_compat_lock(NFPROTO_ARP);
1177         ret = xt_compat_init_offsets(NFPROTO_ARP, compatr->num_entries);
1178         if (ret)
1179                 goto out_unlock;
1180         /* Walk through entries, checking offsets. */
1181         xt_entry_foreach(iter0, entry0, compatr->size) {
1182                 ret = check_compat_entry_size_and_hooks(iter0, info, &size,
1183                                                         entry0,
1184                                                         entry0 + compatr->size);
1185                 if (ret != 0)
1186                         goto out_unlock;
1187                 ++j;
1188         }
1189
1190         ret = -EINVAL;
1191         if (j != compatr->num_entries)
1192                 goto out_unlock;
1193
1194         ret = -ENOMEM;
1195         newinfo = xt_alloc_table_info(size);
1196         if (!newinfo)
1197                 goto out_unlock;
1198
1199         newinfo->number = compatr->num_entries;
1200         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1201                 newinfo->hook_entry[i] = compatr->hook_entry[i];
1202                 newinfo->underflow[i] = compatr->underflow[i];
1203         }
1204         entry1 = newinfo->entries;
1205         pos = entry1;
1206         size = compatr->size;
1207         xt_entry_foreach(iter0, entry0, compatr->size)
1208                 compat_copy_entry_from_user(iter0, &pos, &size,
1209                                             newinfo, entry1);
1210
1211         /* all module references in entry0 are now gone */
1212
1213         xt_compat_flush_offsets(NFPROTO_ARP);
1214         xt_compat_unlock(NFPROTO_ARP);
1215
1216         memcpy(&repl, compatr, sizeof(*compatr));
1217
1218         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1219                 repl.hook_entry[i] = newinfo->hook_entry[i];
1220                 repl.underflow[i] = newinfo->underflow[i];
1221         }
1222
1223         repl.num_counters = 0;
1224         repl.counters = NULL;
1225         repl.size = newinfo->size;
1226         ret = translate_table(net, newinfo, entry1, &repl);
1227         if (ret)
1228                 goto free_newinfo;
1229
1230         *pinfo = newinfo;
1231         *pentry0 = entry1;
1232         xt_free_table_info(info);
1233         return 0;
1234
1235 free_newinfo:
1236         xt_free_table_info(newinfo);
1237         return ret;
1238 out_unlock:
1239         xt_compat_flush_offsets(NFPROTO_ARP);
1240         xt_compat_unlock(NFPROTO_ARP);
1241         xt_entry_foreach(iter0, entry0, compatr->size) {
1242                 if (j-- == 0)
1243                         break;
1244                 compat_release_entry(iter0);
1245         }
1246         return ret;
1247 }
1248
1249 static int compat_do_replace(struct net *net, void __user *user,
1250                              unsigned int len)
1251 {
1252         int ret;
1253         struct compat_arpt_replace tmp;
1254         struct xt_table_info *newinfo;
1255         void *loc_cpu_entry;
1256         struct arpt_entry *iter;
1257
1258         if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
1259                 return -EFAULT;
1260
1261         /* overflow check */
1262         if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
1263                 return -ENOMEM;
1264         if (tmp.num_counters == 0)
1265                 return -EINVAL;
1266
1267         tmp.name[sizeof(tmp.name)-1] = 0;
1268
1269         newinfo = xt_alloc_table_info(tmp.size);
1270         if (!newinfo)
1271                 return -ENOMEM;
1272
1273         loc_cpu_entry = newinfo->entries;
1274         if (copy_from_user(loc_cpu_entry, user + sizeof(tmp), tmp.size) != 0) {
1275                 ret = -EFAULT;
1276                 goto free_newinfo;
1277         }
1278
1279         ret = translate_compat_table(net, &newinfo, &loc_cpu_entry, &tmp);
1280         if (ret != 0)
1281                 goto free_newinfo;
1282
1283         ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
1284                            tmp.num_counters, compat_ptr(tmp.counters));
1285         if (ret)
1286                 goto free_newinfo_untrans;
1287         return 0;
1288
1289  free_newinfo_untrans:
1290         xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
1291                 cleanup_entry(iter, net);
1292  free_newinfo:
1293         xt_free_table_info(newinfo);
1294         return ret;
1295 }
1296
1297 static int compat_do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user,
1298                                   unsigned int len)
1299 {
1300         int ret;
1301
1302         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1303                 return -EPERM;
1304
1305         switch (cmd) {
1306         case ARPT_SO_SET_REPLACE:
1307                 ret = compat_do_replace(sock_net(sk), user, len);
1308                 break;
1309
1310         case ARPT_SO_SET_ADD_COUNTERS:
1311                 ret = do_add_counters(sock_net(sk), user, len, 1);
1312                 break;
1313
1314         default:
1315                 ret = -EINVAL;
1316         }
1317
1318         return ret;
1319 }
1320
1321 static int compat_copy_entry_to_user(struct arpt_entry *e, void __user **dstptr,
1322                                      compat_uint_t *size,
1323                                      struct xt_counters *counters,
1324                                      unsigned int i)
1325 {
1326         struct xt_entry_target *t;
1327         struct compat_arpt_entry __user *ce;
1328         u_int16_t target_offset, next_offset;
1329         compat_uint_t origsize;
1330         int ret;
1331
1332         origsize = *size;
1333         ce = *dstptr;
1334         if (copy_to_user(ce, e, sizeof(struct arpt_entry)) != 0 ||
1335             copy_to_user(&ce->counters, &counters[i],
1336             sizeof(counters[i])) != 0)
1337                 return -EFAULT;
1338
1339         *dstptr += sizeof(struct compat_arpt_entry);
1340         *size -= sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1341
1342         target_offset = e->target_offset - (origsize - *size);
1343
1344         t = arpt_get_target(e);
1345         ret = xt_compat_target_to_user(t, dstptr, size);
1346         if (ret)
1347                 return ret;
1348         next_offset = e->next_offset - (origsize - *size);
1349         if (put_user(target_offset, &ce->target_offset) != 0 ||
1350             put_user(next_offset, &ce->next_offset) != 0)
1351                 return -EFAULT;
1352         return 0;
1353 }
1354
1355 static int compat_copy_entries_to_user(unsigned int total_size,
1356                                        struct xt_table *table,
1357                                        void __user *userptr)
1358 {
1359         struct xt_counters *counters;
1360         const struct xt_table_info *private = table->private;
1361         void __user *pos;
1362         unsigned int size;
1363         int ret = 0;
1364         unsigned int i = 0;
1365         struct arpt_entry *iter;
1366
1367         counters = alloc_counters(table);
1368         if (IS_ERR(counters))
1369                 return PTR_ERR(counters);
1370
1371         pos = userptr;
1372         size = total_size;
1373         xt_entry_foreach(iter, private->entries, total_size) {
1374                 ret = compat_copy_entry_to_user(iter, &pos,
1375                                                 &size, counters, i++);
1376                 if (ret != 0)
1377                         break;
1378         }
1379         vfree(counters);
1380         return ret;
1381 }
1382
1383 struct compat_arpt_get_entries {
1384         char name[XT_TABLE_MAXNAMELEN];
1385         compat_uint_t size;
1386         struct compat_arpt_entry entrytable[];
1387 };
1388
1389 static int compat_get_entries(struct net *net,
1390                               struct compat_arpt_get_entries __user *uptr,
1391                               int *len)
1392 {
1393         int ret;
1394         struct compat_arpt_get_entries get;
1395         struct xt_table *t;
1396
1397         if (*len < sizeof(get))
1398                 return -EINVAL;
1399         if (copy_from_user(&get, uptr, sizeof(get)) != 0)
1400                 return -EFAULT;
1401         if (*len != sizeof(struct compat_arpt_get_entries) + get.size)
1402                 return -EINVAL;
1403
1404         get.name[sizeof(get.name) - 1] = '\0';
1405
1406         xt_compat_lock(NFPROTO_ARP);
1407         t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
1408         if (!IS_ERR(t)) {
1409                 const struct xt_table_info *private = t->private;
1410                 struct xt_table_info info;
1411
1412                 ret = compat_table_info(private, &info);
1413                 if (!ret && get.size == info.size) {
1414                         ret = compat_copy_entries_to_user(private->size,
1415                                                           t, uptr->entrytable);
1416                 } else if (!ret)
1417                         ret = -EAGAIN;
1418
1419                 xt_compat_flush_offsets(NFPROTO_ARP);
1420                 module_put(t->me);
1421                 xt_table_unlock(t);
1422         } else
1423                 ret = PTR_ERR(t);
1424
1425         xt_compat_unlock(NFPROTO_ARP);
1426         return ret;
1427 }
1428
1429 static int do_arpt_get_ctl(struct sock *, int, void __user *, int *);
1430
1431 static int compat_do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user,
1432                                   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, 1);
1442                 break;
1443         case ARPT_SO_GET_ENTRIES:
1444                 ret = compat_get_entries(sock_net(sk), user, len);
1445                 break;
1446         default:
1447                 ret = do_arpt_get_ctl(sk, cmd, user, len);
1448         }
1449         return ret;
1450 }
1451 #endif
1452
1453 static int do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
1454 {
1455         int ret;
1456
1457         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1458                 return -EPERM;
1459
1460         switch (cmd) {
1461         case ARPT_SO_SET_REPLACE:
1462                 ret = do_replace(sock_net(sk), user, len);
1463                 break;
1464
1465         case ARPT_SO_SET_ADD_COUNTERS:
1466                 ret = do_add_counters(sock_net(sk), user, len, 0);
1467                 break;
1468
1469         default:
1470                 ret = -EINVAL;
1471         }
1472
1473         return ret;
1474 }
1475
1476 static int do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
1477 {
1478         int ret;
1479
1480         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1481                 return -EPERM;
1482
1483         switch (cmd) {
1484         case ARPT_SO_GET_INFO:
1485                 ret = get_info(sock_net(sk), user, len, 0);
1486                 break;
1487
1488         case ARPT_SO_GET_ENTRIES:
1489                 ret = get_entries(sock_net(sk), user, len);
1490                 break;
1491
1492         case ARPT_SO_GET_REVISION_TARGET: {
1493                 struct xt_get_revision rev;
1494
1495                 if (*len != sizeof(rev)) {
1496                         ret = -EINVAL;
1497                         break;
1498                 }
1499                 if (copy_from_user(&rev, user, sizeof(rev)) != 0) {
1500                         ret = -EFAULT;
1501                         break;
1502                 }
1503                 rev.name[sizeof(rev.name)-1] = 0;
1504
1505                 try_then_request_module(xt_find_revision(NFPROTO_ARP, rev.name,
1506                                                          rev.revision, 1, &ret),
1507                                         "arpt_%s", rev.name);
1508                 break;
1509         }
1510
1511         default:
1512                 ret = -EINVAL;
1513         }
1514
1515         return ret;
1516 }
1517
1518 static void __arpt_unregister_table(struct net *net, struct xt_table *table)
1519 {
1520         struct xt_table_info *private;
1521         void *loc_cpu_entry;
1522         struct module *table_owner = table->me;
1523         struct arpt_entry *iter;
1524
1525         private = xt_unregister_table(table);
1526
1527         /* Decrease module usage counts and free resources */
1528         loc_cpu_entry = private->entries;
1529         xt_entry_foreach(iter, loc_cpu_entry, private->size)
1530                 cleanup_entry(iter, net);
1531         if (private->number > private->initial_entries)
1532                 module_put(table_owner);
1533         xt_free_table_info(private);
1534 }
1535
1536 int arpt_register_table(struct net *net,
1537                         const struct xt_table *table,
1538                         const struct arpt_replace *repl,
1539                         const struct nf_hook_ops *ops,
1540                         struct xt_table **res)
1541 {
1542         int ret;
1543         struct xt_table_info *newinfo;
1544         struct xt_table_info bootstrap = {0};
1545         void *loc_cpu_entry;
1546         struct xt_table *new_table;
1547
1548         newinfo = xt_alloc_table_info(repl->size);
1549         if (!newinfo)
1550                 return -ENOMEM;
1551
1552         loc_cpu_entry = newinfo->entries;
1553         memcpy(loc_cpu_entry, repl->entries, repl->size);
1554
1555         ret = translate_table(net, newinfo, loc_cpu_entry, repl);
1556         if (ret != 0)
1557                 goto out_free;
1558
1559         new_table = xt_register_table(net, table, &bootstrap, newinfo);
1560         if (IS_ERR(new_table)) {
1561                 ret = PTR_ERR(new_table);
1562                 goto out_free;
1563         }
1564
1565         /* set res now, will see skbs right after nf_register_net_hooks */
1566         WRITE_ONCE(*res, new_table);
1567
1568         ret = nf_register_net_hooks(net, ops, hweight32(table->valid_hooks));
1569         if (ret != 0) {
1570                 __arpt_unregister_table(net, new_table);
1571                 *res = NULL;
1572         }
1573
1574         return ret;
1575
1576 out_free:
1577         xt_free_table_info(newinfo);
1578         return ret;
1579 }
1580
1581 void arpt_unregister_table(struct net *net, struct xt_table *table,
1582                            const struct nf_hook_ops *ops)
1583 {
1584         nf_unregister_net_hooks(net, ops, hweight32(table->valid_hooks));
1585         __arpt_unregister_table(net, table);
1586 }
1587
1588 /* The built-in targets: standard (NULL) and error. */
1589 static struct xt_target arpt_builtin_tg[] __read_mostly = {
1590         {
1591                 .name             = XT_STANDARD_TARGET,
1592                 .targetsize       = sizeof(int),
1593                 .family           = NFPROTO_ARP,
1594 #ifdef CONFIG_COMPAT
1595                 .compatsize       = sizeof(compat_int_t),
1596                 .compat_from_user = compat_standard_from_user,
1597                 .compat_to_user   = compat_standard_to_user,
1598 #endif
1599         },
1600         {
1601                 .name             = XT_ERROR_TARGET,
1602                 .target           = arpt_error,
1603                 .targetsize       = XT_FUNCTION_MAXNAMELEN,
1604                 .family           = NFPROTO_ARP,
1605         },
1606 };
1607
1608 static struct nf_sockopt_ops arpt_sockopts = {
1609         .pf             = PF_INET,
1610         .set_optmin     = ARPT_BASE_CTL,
1611         .set_optmax     = ARPT_SO_SET_MAX+1,
1612         .set            = do_arpt_set_ctl,
1613 #ifdef CONFIG_COMPAT
1614         .compat_set     = compat_do_arpt_set_ctl,
1615 #endif
1616         .get_optmin     = ARPT_BASE_CTL,
1617         .get_optmax     = ARPT_SO_GET_MAX+1,
1618         .get            = do_arpt_get_ctl,
1619 #ifdef CONFIG_COMPAT
1620         .compat_get     = compat_do_arpt_get_ctl,
1621 #endif
1622         .owner          = THIS_MODULE,
1623 };
1624
1625 static int __net_init arp_tables_net_init(struct net *net)
1626 {
1627         return xt_proto_init(net, NFPROTO_ARP);
1628 }
1629
1630 static void __net_exit arp_tables_net_exit(struct net *net)
1631 {
1632         xt_proto_fini(net, NFPROTO_ARP);
1633 }
1634
1635 static struct pernet_operations arp_tables_net_ops = {
1636         .init = arp_tables_net_init,
1637         .exit = arp_tables_net_exit,
1638 };
1639
1640 static int __init arp_tables_init(void)
1641 {
1642         int ret;
1643
1644         ret = register_pernet_subsys(&arp_tables_net_ops);
1645         if (ret < 0)
1646                 goto err1;
1647
1648         /* No one else will be downing sem now, so we won't sleep */
1649         ret = xt_register_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1650         if (ret < 0)
1651                 goto err2;
1652
1653         /* Register setsockopt */
1654         ret = nf_register_sockopt(&arpt_sockopts);
1655         if (ret < 0)
1656                 goto err4;
1657
1658         return 0;
1659
1660 err4:
1661         xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1662 err2:
1663         unregister_pernet_subsys(&arp_tables_net_ops);
1664 err1:
1665         return ret;
1666 }
1667
1668 static void __exit arp_tables_fini(void)
1669 {
1670         nf_unregister_sockopt(&arpt_sockopts);
1671         xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1672         unregister_pernet_subsys(&arp_tables_net_ops);
1673 }
1674
1675 EXPORT_SYMBOL(arpt_register_table);
1676 EXPORT_SYMBOL(arpt_unregister_table);
1677 EXPORT_SYMBOL(arpt_do_table);
1678
1679 module_init(arp_tables_init);
1680 module_exit(arp_tables_fini);