net/ipv4/netfilter/arp_tables.c

   1 /*
   2  * Packet matching code for ARP packets.
   3  *
   4  * Based heavily, if not almost entirely, upon ip_tables.c framework.
   5  *
   6  * Some ARP specific bits are:
   7  *
   8  * Copyright (C) 2002 David S. Miller (davem@redhat.com)
   9  * Copyright (C) 2006-2009 Patrick McHardy <kaber@trash.net>
  10  *
  11  */
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13 #include <linux/kernel.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/netdevice.h>
  16 #include <linux/capability.h>
  17 #include <linux/if_arp.h>
  18 #include <linux/kmod.h>
  19 #include <linux/vmalloc.h>
  20 #include <linux/proc_fs.h>
  21 #include <linux/module.h>
  22 #include <linux/init.h>
  23 #include <linux/mutex.h>
  24 #include <linux/err.h>
  25 #include <net/compat.h>
  26 #include <net/sock.h>
  27 #include <asm/uaccess.h>
  28
  29 #include <linux/netfilter/x_tables.h>
  30 #include <linux/netfilter_arp/arp_tables.h>
  31 #include "../../netfilter/xt_repldata.h"
  32
  33 MODULE_LICENSE("GPL");
  34 MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
  35 MODULE_DESCRIPTION("arptables core");
  36
  37 /*#define DEBUG_ARP_TABLES*/
  38 /*#define DEBUG_ARP_TABLES_USER*/
  39
  40 #ifdef DEBUG_ARP_TABLES
  41 #define dprintf(format, args...)  pr_debug(format, ## args)
  42 #else
  43 #define dprintf(format, args...)
  44 #endif
  45
  46 #ifdef DEBUG_ARP_TABLES_USER
  47 #define duprintf(format, args...) pr_debug(format, ## args)
  48 #else
  49 #define duprintf(format, args...)
  50 #endif
  51
  52 #ifdef CONFIG_NETFILTER_DEBUG
  53 #define ARP_NF_ASSERT(x)        WARN_ON(!(x))
  54 #else
  55 #define ARP_NF_ASSERT(x)
  56 #endif
  57
  58 void *arpt_alloc_initial_table(const struct xt_table *info)
  59 {
  60         return xt_alloc_initial_table(arpt, ARPT);
  61 }
  62 EXPORT_SYMBOL_GPL(arpt_alloc_initial_table);
  63
  64 static inline int arp_devaddr_compare(const struct arpt_devaddr_info *ap,
  65                                       const char *hdr_addr, int len)
  66 {
  67         int i, ret;
  68
  69         if (len > ARPT_DEV_ADDR_LEN_MAX)
  70                 len = ARPT_DEV_ADDR_LEN_MAX;
  71
  72         ret = 0;
  73         for (i = 0; i < len; i++)
  74                 ret |= (hdr_addr[i] ^ ap->addr[i]) & ap->mask[i];
  75
  76         return ret != 0;
  77 }
  78
  79 /*
  80  * Unfortunately, _b and _mask are not aligned to an int (or long int)
  81  * Some arches dont care, unrolling the loop is a win on them.
  82  * For other arches, we only have a 16bit alignement.
  83  */
  84 static unsigned long ifname_compare(const char *_a, const char *_b, const char *_mask)
  85 {
  86 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
  87         unsigned long ret = ifname_compare_aligned(_a, _b, _mask);
  88 #else
  89         unsigned long ret = 0;
  90         const u16 *a = (const u16 *)_a;
  91         const u16 *b = (const u16 *)_b;
  92         const u16 *mask = (const u16 *)_mask;
  93         int i;
  94
  95         for (i = 0; i < IFNAMSIZ/sizeof(u16); i++)
  96                 ret |= (a[i] ^ b[i]) & mask[i];
  97 #endif
  98         return ret;
  99 }
 100
 101 /* Returns whether packet matches rule or not. */
 102 static inline int arp_packet_match(const struct arphdr *arphdr,
 103                                    struct net_device *dev,
 104                                    const char *indev,
 105                                    const char *outdev,
 106                                    const struct arpt_arp *arpinfo)
 107 {
 108         const char *arpptr = (char *)(arphdr + 1);
 109         const char *src_devaddr, *tgt_devaddr;
 110         __be32 src_ipaddr, tgt_ipaddr;
 111         long ret;
 112
 113 #define FWINV(bool, invflg) ((bool) ^ !!(arpinfo->invflags & (invflg)))
 114
 115         if (FWINV((arphdr->ar_op & arpinfo->arpop_mask) != arpinfo->arpop,
 116                   ARPT_INV_ARPOP)) {
 117                 dprintf("ARP operation field mismatch.\n");
 118                 dprintf("ar_op: %04x info->arpop: %04x info->arpop_mask: %04x\n",
 119                         arphdr->ar_op, arpinfo->arpop, arpinfo->arpop_mask);
 120                 return 0;
 121         }
 122
 123         if (FWINV((arphdr->ar_hrd & arpinfo->arhrd_mask) != arpinfo->arhrd,
 124                   ARPT_INV_ARPHRD)) {
 125                 dprintf("ARP hardware address format mismatch.\n");
 126                 dprintf("ar_hrd: %04x info->arhrd: %04x info->arhrd_mask: %04x\n",
 127                         arphdr->ar_hrd, arpinfo->arhrd, arpinfo->arhrd_mask);
 128                 return 0;
 129         }
 130
 131         if (FWINV((arphdr->ar_pro & arpinfo->arpro_mask) != arpinfo->arpro,
 132                   ARPT_INV_ARPPRO)) {
 133                 dprintf("ARP protocol address format mismatch.\n");
 134                 dprintf("ar_pro: %04x info->arpro: %04x info->arpro_mask: %04x\n",
 135                         arphdr->ar_pro, arpinfo->arpro, arpinfo->arpro_mask);
 136                 return 0;
 137         }
 138
 139         if (FWINV((arphdr->ar_hln & arpinfo->arhln_mask) != arpinfo->arhln,
 140                   ARPT_INV_ARPHLN)) {
 141                 dprintf("ARP hardware address length mismatch.\n");
 142                 dprintf("ar_hln: %02x info->arhln: %02x info->arhln_mask: %02x\n",
 143                         arphdr->ar_hln, arpinfo->arhln, arpinfo->arhln_mask);
 144                 return 0;
 145         }
 146
 147         src_devaddr = arpptr;
 148         arpptr += dev->addr_len;
 149         memcpy(&src_ipaddr, arpptr, sizeof(u32));
 150         arpptr += sizeof(u32);
 151         tgt_devaddr = arpptr;
 152         arpptr += dev->addr_len;
 153         memcpy(&tgt_ipaddr, arpptr, sizeof(u32));
 154
 155         if (FWINV(arp_devaddr_compare(&arpinfo->src_devaddr, src_devaddr, dev->addr_len),
 156                   ARPT_INV_SRCDEVADDR) ||
 157             FWINV(arp_devaddr_compare(&arpinfo->tgt_devaddr, tgt_devaddr, dev->addr_len),
 158                   ARPT_INV_TGTDEVADDR)) {
 159                 dprintf("Source or target device address mismatch.\n");
 160
 161                 return 0;
 162         }
 163
 164         if (FWINV((src_ipaddr & arpinfo->smsk.s_addr) != arpinfo->src.s_addr,
 165                   ARPT_INV_SRCIP) ||
 166             FWINV(((tgt_ipaddr & arpinfo->tmsk.s_addr) != arpinfo->tgt.s_addr),
 167                   ARPT_INV_TGTIP)) {
 168                 dprintf("Source or target IP address mismatch.\n");
 169
 170                 dprintf("SRC: %pI4. Mask: %pI4. Target: %pI4.%s\n",
 171                         &src_ipaddr,
 172                         &arpinfo->smsk.s_addr,
 173                         &arpinfo->src.s_addr,
 174                         arpinfo->invflags & ARPT_INV_SRCIP ? " (INV)" : "");
 175                 dprintf("TGT: %pI4 Mask: %pI4 Target: %pI4.%s\n",
 176                         &tgt_ipaddr,
 177                         &arpinfo->tmsk.s_addr,
 178                         &arpinfo->tgt.s_addr,
 179                         arpinfo->invflags & ARPT_INV_TGTIP ? " (INV)" : "");
 180                 return 0;
 181         }
 182
 183         /* Look for ifname matches.  */
 184         ret = ifname_compare(indev, arpinfo->iniface, arpinfo->iniface_mask);
 185
 186         if (FWINV(ret != 0, ARPT_INV_VIA_IN)) {
 187                 dprintf("VIA in mismatch (%s vs %s).%s\n",
 188                         indev, arpinfo->iniface,
 189                         arpinfo->invflags & ARPT_INV_VIA_IN ? " (INV)" : "");
 190                 return 0;
 191         }
 192
 193         ret = ifname_compare(outdev, arpinfo->outiface, arpinfo->outiface_mask);
 194
 195         if (FWINV(ret != 0, ARPT_INV_VIA_OUT)) {
 196                 dprintf("VIA out mismatch (%s vs %s).%s\n",
 197                         outdev, arpinfo->outiface,
 198                         arpinfo->invflags & ARPT_INV_VIA_OUT ? " (INV)" : "");
 199                 return 0;
 200         }
 201
 202         return 1;
 203 #undef FWINV
 204 }
 205
 206 static inline int arp_checkentry(const struct arpt_arp *arp)
 207 {
 208         if (arp->flags & ~ARPT_F_MASK) {
 209                 duprintf("Unknown flag bits set: %08X\n",
 210                          arp->flags & ~ARPT_F_MASK);
 211                 return 0;
 212         }
 213         if (arp->invflags & ~ARPT_INV_MASK) {
 214                 duprintf("Unknown invflag bits set: %08X\n",
 215                          arp->invflags & ~ARPT_INV_MASK);
 216                 return 0;
 217         }
 218
 219         return 1;
 220 }
 221
 222 static unsigned int
 223 arpt_error(struct sk_buff *skb, const struct xt_action_param *par)
 224 {
 225         net_err_ratelimited("arp_tables: error: '%s'\n",
 226                             (const char *)par->targinfo);
 227
 228         return NF_DROP;
 229 }
 230
 231 static inline const struct xt_entry_target *
 232 arpt_get_target_c(const struct arpt_entry *e)
 233 {
 234         return arpt_get_target((struct arpt_entry *)e);
 235 }
 236
 237 static inline struct arpt_entry *
 238 get_entry(const void *base, unsigned int offset)
 239 {
 240         return (struct arpt_entry *)(base + offset);
 241 }
 242
 243 static inline
 244 struct arpt_entry *arpt_next_entry(const struct arpt_entry *entry)
 245 {
 246         return (void *)entry + entry->next_offset;
 247 }
 248
 249 unsigned int arpt_do_table(struct sk_buff *skb,
 250                            const struct nf_hook_state *state,
 251                            struct xt_table *table)
 252 {
 253         unsigned int hook = state->hook;
 254         static const char nulldevname[IFNAMSIZ] __attribute__((aligned(sizeof(long))));
 255         unsigned int verdict = NF_DROP;
 256         const struct arphdr *arp;
 257         struct arpt_entry *e, **jumpstack;
 258         const char *indev, *outdev;
 259         const void *table_base;
 260         unsigned int cpu, stackidx = 0;
 261         const struct xt_table_info *private;
 262         struct xt_action_param acpar;
 263         unsigned int addend;
 264
 265         if (!pskb_may_pull(skb, arp_hdr_len(skb->dev)))
 266                 return NF_DROP;
 267
 268         indev = state->in ? state->in->name : nulldevname;
 269         outdev = state->out ? state->out->name : nulldevname;
 270
 271         local_bh_disable();
 272         addend = xt_write_recseq_begin();
 273         private = table->private;
 274         cpu     = smp_processor_id();
 275         /*
 276          * Ensure we load private-> members after we've fetched the base
 277          * pointer.
 278          */
 279         smp_read_barrier_depends();
 280         table_base = private->entries;
 281         jumpstack  = (struct arpt_entry **)private->jumpstack[cpu];
 282
 283         /* No TEE support for arptables, so no need to switch to alternate
 284          * stack.  All targets that reenter must return absolute verdicts.
 285          */
 286         e = get_entry(table_base, private->hook_entry[hook]);
 287
 288         acpar.net     = state->net;
 289         acpar.in      = state->in;
 290         acpar.out     = state->out;
 291         acpar.hooknum = hook;
 292         acpar.family  = NFPROTO_ARP;
 293         acpar.hotdrop = false;
 294
 295         arp = arp_hdr(skb);
 296         do {
 297                 const struct xt_entry_target *t;
 298                 struct xt_counters *counter;
 299
 300                 if (!arp_packet_match(arp, skb->dev, indev, outdev, &e->arp)) {
 301                         e = arpt_next_entry(e);
 302                         continue;
 303                 }
 304
 305                 counter = xt_get_this_cpu_counter(&e->counters);
 306                 ADD_COUNTER(*counter, arp_hdr_len(skb->dev), 1);
 307
 308                 t = arpt_get_target_c(e);
 309
 310                 /* Standard target? */
 311                 if (!t->u.kernel.target->target) {
 312                         int v;
 313
 314                         v = ((struct xt_standard_target *)t)->verdict;
 315                         if (v < 0) {
 316                                 /* Pop from stack? */
 317                                 if (v != XT_RETURN) {
 318                                         verdict = (unsigned int)(-v) - 1;
 319                                         break;
 320                                 }
 321                                 if (stackidx == 0) {
 322                                         e = get_entry(table_base,
 323                                                       private->underflow[hook]);
 324                                 } else {
 325                                         e = jumpstack[--stackidx];
 326                                         e = arpt_next_entry(e);
 327                                 }
 328                                 continue;
 329                         }
 330                         if (table_base + v
 331                             != arpt_next_entry(e)) {
 332                                 jumpstack[stackidx++] = e;
 333                         }
 334
 335                         e = get_entry(table_base, v);
 336                         continue;
 337                 }
 338
 339                 acpar.target   = t->u.kernel.target;
 340                 acpar.targinfo = t->data;
 341                 verdict = t->u.kernel.target->target(skb, &acpar);
 342
 343                 /* Target might have changed stuff. */
 344                 arp = arp_hdr(skb);
 345
 346                 if (verdict == XT_CONTINUE)
 347                         e = arpt_next_entry(e);
 348                 else
 349                         /* Verdict */
 350                         break;
 351         } while (!acpar.hotdrop);
 352         xt_write_recseq_end(addend);
 353         local_bh_enable();
 354
 355         if (acpar.hotdrop)
 356                 return NF_DROP;
 357         else
 358                 return verdict;
 359 }
 360
 361 /* All zeroes == unconditional rule. */
 362 static inline bool unconditional(const struct arpt_entry *e)
 363 {
 364         static const struct arpt_arp uncond;
 365
 366         return e->target_offset == sizeof(struct arpt_entry) &&
 367                memcmp(&e->arp, &uncond, sizeof(uncond)) == 0;
 368 }
 369
 370 static bool find_jump_target(const struct xt_table_info *t,
 371                              const struct arpt_entry *target)
 372 {
 373         struct arpt_entry *iter;
 374
 375         xt_entry_foreach(iter, t->entries, t->size) {
 376                  if (iter == target)
 377                         return true;
 378         }
 379         return false;
 380 }
 381
 382 /* Figures out from what hook each rule can be called: returns 0 if
 383  * there are loops.  Puts hook bitmask in comefrom.
 384  */
 385 static int mark_source_chains(const struct xt_table_info *newinfo,
 386                               unsigned int valid_hooks, void *entry0)
 387 {
 388         unsigned int hook;
 389
 390         /* No recursion; use packet counter to save back ptrs (reset
 391          * to 0 as we leave), and comefrom to save source hook bitmask.
 392          */
 393         for (hook = 0; hook < NF_ARP_NUMHOOKS; hook++) {
 394                 unsigned int pos = newinfo->hook_entry[hook];
 395                 struct arpt_entry *e
 396                         = (struct arpt_entry *)(entry0 + pos);
 397
 398                 if (!(valid_hooks & (1 << hook)))
 399                         continue;
 400
 401                 /* Set initial back pointer. */
 402                 e->counters.pcnt = pos;
 403
 404                 for (;;) {
 405                         const struct xt_standard_target *t
 406                                 = (void *)arpt_get_target_c(e);
 407                         int visited = e->comefrom & (1 << hook);
 408
 409                         if (e->comefrom & (1 << NF_ARP_NUMHOOKS)) {
 410                                 pr_notice("arptables: loop hook %u pos %u %08X.\n",
 411                                        hook, pos, e->comefrom);
 412                                 return 0;
 413                         }
 414                         e->comefrom
 415                                 |= ((1 << hook) | (1 << NF_ARP_NUMHOOKS));
 416
 417                         /* Unconditional return/END. */
 418                         if ((unconditional(e) &&
 419                              (strcmp(t->target.u.user.name,
 420                                      XT_STANDARD_TARGET) == 0) &&
 421                              t->verdict < 0) || visited) {
 422                                 unsigned int oldpos, size;
 423
 424                                 if ((strcmp(t->target.u.user.name,
 425                                             XT_STANDARD_TARGET) == 0) &&
 426                                     t->verdict < -NF_MAX_VERDICT - 1) {
 427                                         duprintf("mark_source_chains: bad "
 428                                                 "negative verdict (%i)\n",
 429                                                                 t->verdict);
 430                                         return 0;
 431                                 }
 432
 433                                 /* Return: backtrack through the last
 434                                  * big jump.
 435                                  */
 436                                 do {
 437                                         e->comefrom ^= (1<<NF_ARP_NUMHOOKS);
 438                                         oldpos = pos;
 439                                         pos = e->counters.pcnt;
 440                                         e->counters.pcnt = 0;
 441
 442                                         /* We're at the start. */
 443                                         if (pos == oldpos)
 444                                                 goto next;
 445
 446                                         e = (struct arpt_entry *)
 447                                                 (entry0 + pos);
 448                                 } while (oldpos == pos + e->next_offset);
 449
 450                                 /* Move along one */
 451                                 size = e->next_offset;
 452                                 e = (struct arpt_entry *)
 453                                         (entry0 + pos + size);
 454                                 if (pos + size >= newinfo->size)
 455                                         return 0;
 456                                 e->counters.pcnt = pos;
 457                                 pos += size;
 458                         } else {
 459                                 int newpos = t->verdict;
 460
 461                                 if (strcmp(t->target.u.user.name,
 462                                            XT_STANDARD_TARGET) == 0 &&
 463                                     newpos >= 0) {
 464                                         if (newpos > newinfo->size -
 465                                                 sizeof(struct arpt_entry)) {
 466                                                 duprintf("mark_source_chains: "
 467                                                         "bad verdict (%i)\n",
 468                                                                 newpos);
 469                                                 return 0;
 470                                         }
 471
 472                                         /* This a jump; chase it. */
 473                                         duprintf("Jump rule %u -> %u\n",
 474                                                  pos, newpos);
 475                                         e = (struct arpt_entry *)
 476                                                 (entry0 + newpos);
 477                                         if (!find_jump_target(newinfo, e))
 478                                                 return 0;
 479                                 } else {
 480                                         /* ... this is a fallthru */
 481                                         newpos = pos + e->next_offset;
 482                                         if (newpos >= newinfo->size)
 483                                                 return 0;
 484                                 }
 485                                 e = (struct arpt_entry *)
 486                                         (entry0 + newpos);
 487                                 e->counters.pcnt = pos;
 488                                 pos = newpos;
 489                         }
 490                 }
 491 next:
 492                 duprintf("Finished chain %u\n", hook);
 493         }
 494         return 1;
 495 }
 496
 497 static inline int check_entry(const struct arpt_entry *e)
 498 {
 499         const struct xt_entry_target *t;
 500
 501         if (!arp_checkentry(&e->arp))
 502                 return -EINVAL;
 503
 504         if (e->target_offset + sizeof(struct xt_entry_target) > e->next_offset)
 505                 return -EINVAL;
 506
 507         t = arpt_get_target_c(e);
 508         if (e->target_offset + t->u.target_size > e->next_offset)
 509                 return -EINVAL;
 510
 511         return 0;
 512 }
 513
 514 static inline int check_target(struct arpt_entry *e, const char *name)
 515 {
 516         struct xt_entry_target *t = arpt_get_target(e);
 517         int ret;
 518         struct xt_tgchk_param par = {
 519                 .table     = name,
 520                 .entryinfo = e,
 521                 .target    = t->u.kernel.target,
 522                 .targinfo  = t->data,
 523                 .hook_mask = e->comefrom,
 524                 .family    = NFPROTO_ARP,
 525         };
 526
 527         ret = xt_check_target(&par, t->u.target_size - sizeof(*t), 0, false);
 528         if (ret < 0) {
 529                 duprintf("arp_tables: check failed for `%s'.\n",
 530                          t->u.kernel.target->name);
 531                 return ret;
 532         }
 533         return 0;
 534 }
 535
 536 static inline int
 537 find_check_entry(struct arpt_entry *e, const char *name, unsigned int size)
 538 {
 539         struct xt_entry_target *t;
 540         struct xt_target *target;
 541         int ret;
 542
 543         e->counters.pcnt = xt_percpu_counter_alloc();
 544         if (IS_ERR_VALUE(e->counters.pcnt))
 545                 return -ENOMEM;
 546
 547         t = arpt_get_target(e);
 548         target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
 549                                         t->u.user.revision);
 550         if (IS_ERR(target)) {
 551                 duprintf("find_check_entry: `%s' not found\n", t->u.user.name);
 552                 ret = PTR_ERR(target);
 553                 goto out;
 554         }
 555         t->u.kernel.target = target;
 556
 557         ret = check_target(e, name);
 558         if (ret)
 559                 goto err;
 560         return 0;
 561 err:
 562         module_put(t->u.kernel.target->me);
 563 out:
 564         xt_percpu_counter_free(e->counters.pcnt);
 565
 566         return ret;
 567 }
 568
 569 static bool check_underflow(const struct arpt_entry *e)
 570 {
 571         const struct xt_entry_target *t;
 572         unsigned int verdict;
 573
 574         if (!unconditional(e))
 575                 return false;
 576         t = arpt_get_target_c(e);
 577         if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
 578                 return false;
 579         verdict = ((struct xt_standard_target *)t)->verdict;
 580         verdict = -verdict - 1;
 581         return verdict == NF_DROP || verdict == NF_ACCEPT;
 582 }
 583
 584 static inline int check_entry_size_and_hooks(struct arpt_entry *e,
 585                                              struct xt_table_info *newinfo,
 586                                              const unsigned char *base,
 587                                              const unsigned char *limit,
 588                                              const unsigned int *hook_entries,
 589                                              const unsigned int *underflows,
 590                                              unsigned int valid_hooks)
 591 {
 592         unsigned int h;
 593         int err;
 594
 595         if ((unsigned long)e % __alignof__(struct arpt_entry) != 0 ||
 596             (unsigned char *)e + sizeof(struct arpt_entry) >= limit ||
 597             (unsigned char *)e + e->next_offset > limit) {
 598                 duprintf("Bad offset %p\n", e);
 599                 return -EINVAL;
 600         }
 601
 602         if (e->next_offset
 603             < sizeof(struct arpt_entry) + sizeof(struct xt_entry_target)) {
 604                 duprintf("checking: element %p size %u\n",
 605                          e, e->next_offset);
 606                 return -EINVAL;
 607         }
 608
 609         err = check_entry(e);
 610         if (err)
 611                 return err;
 612
 613         /* Check hooks & underflows */
 614         for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
 615                 if (!(valid_hooks & (1 << h)))
 616                         continue;
 617                 if ((unsigned char *)e - base == hook_entries[h])
 618                         newinfo->hook_entry[h] = hook_entries[h];
 619                 if ((unsigned char *)e - base == underflows[h]) {
 620                         if (!check_underflow(e)) {
 621                                 pr_debug("Underflows must be unconditional and "
 622                                          "use the STANDARD target with "
 623                                          "ACCEPT/DROP\n");
 624                                 return -EINVAL;
 625                         }
 626                         newinfo->underflow[h] = underflows[h];
 627                 }
 628         }
 629
 630         /* Clear counters and comefrom */
 631         e->counters = ((struct xt_counters) { 0, 0 });
 632         e->comefrom = 0;
 633         return 0;
 634 }
 635
 636 static inline void cleanup_entry(struct arpt_entry *e)
 637 {
 638         struct xt_tgdtor_param par;
 639         struct xt_entry_target *t;
 640
 641         t = arpt_get_target(e);
 642         par.target   = t->u.kernel.target;
 643         par.targinfo = t->data;
 644         par.family   = NFPROTO_ARP;
 645         if (par.target->destroy != NULL)
 646                 par.target->destroy(&par);
 647         module_put(par.target->me);
 648         xt_percpu_counter_free(e->counters.pcnt);
 649 }
 650
 651 /* Checks and translates the user-supplied table segment (held in
 652  * newinfo).
 653  */
 654 static int translate_table(struct xt_table_info *newinfo, void *entry0,
 655                            const struct arpt_replace *repl)
 656 {
 657         struct arpt_entry *iter;
 658         unsigned int i;
 659         int ret = 0;
 660
 661         newinfo->size = repl->size;
 662         newinfo->number = repl->num_entries;
 663
 664         /* Init all hooks to impossible value. */
 665         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
 666                 newinfo->hook_entry[i] = 0xFFFFFFFF;
 667                 newinfo->underflow[i] = 0xFFFFFFFF;
 668         }
 669
 670         duprintf("translate_table: size %u\n", newinfo->size);
 671         i = 0;
 672
 673         /* Walk through entries, checking offsets. */
 674         xt_entry_foreach(iter, entry0, newinfo->size) {
 675                 ret = check_entry_size_and_hooks(iter, newinfo, entry0,
 676                                                  entry0 + repl->size,
 677                                                  repl->hook_entry,
 678                                                  repl->underflow,
 679                                                  repl->valid_hooks);
 680                 if (ret != 0)
 681                         break;
 682                 ++i;
 683                 if (strcmp(arpt_get_target(iter)->u.user.name,
 684                     XT_ERROR_TARGET) == 0)
 685                         ++newinfo->stacksize;
 686         }
 687         duprintf("translate_table: ARPT_ENTRY_ITERATE gives %d\n", ret);
 688         if (ret != 0)
 689                 return ret;
 690
 691         if (i != repl->num_entries) {
 692                 duprintf("translate_table: %u not %u entries\n",
 693                          i, repl->num_entries);
 694                 return -EINVAL;
 695         }
 696
 697         /* Check hooks all assigned */
 698         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
 699                 /* Only hooks which are valid */
 700                 if (!(repl->valid_hooks & (1 << i)))
 701                         continue;
 702                 if (newinfo->hook_entry[i] == 0xFFFFFFFF) {
 703                         duprintf("Invalid hook entry %u %u\n",
 704                                  i, repl->hook_entry[i]);
 705                         return -EINVAL;
 706                 }
 707                 if (newinfo->underflow[i] == 0xFFFFFFFF) {
 708                         duprintf("Invalid underflow %u %u\n",
 709                                  i, repl->underflow[i]);
 710                         return -EINVAL;
 711                 }
 712         }
 713
 714         if (!mark_source_chains(newinfo, repl->valid_hooks, entry0))
 715                 return -ELOOP;
 716
 717         /* Finally, each sanity check must pass */
 718         i = 0;
 719         xt_entry_foreach(iter, entry0, newinfo->size) {
 720                 ret = find_check_entry(iter, repl->name, repl->size);
 721                 if (ret != 0)
 722                         break;
 723                 ++i;
 724         }
 725
 726         if (ret != 0) {
 727                 xt_entry_foreach(iter, entry0, newinfo->size) {
 728                         if (i-- == 0)
 729                                 break;
 730                         cleanup_entry(iter);
 731                 }
 732                 return ret;
 733         }
 734
 735         return ret;
 736 }
 737
 738 static void get_counters(const struct xt_table_info *t,
 739                          struct xt_counters counters[])
 740 {
 741         struct arpt_entry *iter;
 742         unsigned int cpu;
 743         unsigned int i;
 744
 745         for_each_possible_cpu(cpu) {
 746                 seqcount_t *s = &per_cpu(xt_recseq, cpu);
 747
 748                 i = 0;
 749                 xt_entry_foreach(iter, t->entries, t->size) {
 750                         struct xt_counters *tmp;
 751                         u64 bcnt, pcnt;
 752                         unsigned int start;
 753
 754                         tmp = xt_get_per_cpu_counter(&iter->counters, cpu);
 755                         do {
 756                                 start = read_seqcount_begin(s);
 757                                 bcnt = tmp->bcnt;
 758                                 pcnt = tmp->pcnt;
 759                         } while (read_seqcount_retry(s, start));
 760
 761                         ADD_COUNTER(counters[i], bcnt, pcnt);
 762                         ++i;
 763                 }
 764         }
 765 }
 766
 767 static struct xt_counters *alloc_counters(const struct xt_table *table)
 768 {
 769         unsigned int countersize;
 770         struct xt_counters *counters;
 771         const struct xt_table_info *private = table->private;
 772
 773         /* We need atomic snapshot of counters: rest doesn't change
 774          * (other than comefrom, which userspace doesn't care
 775          * about).
 776          */
 777         countersize = sizeof(struct xt_counters) * private->number;
 778         counters = vzalloc(countersize);
 779
 780         if (counters == NULL)
 781                 return ERR_PTR(-ENOMEM);
 782
 783         get_counters(private, counters);
 784
 785         return counters;
 786 }
 787
 788 static int copy_entries_to_user(unsigned int total_size,
 789                                 const struct xt_table *table,
 790                                 void __user *userptr)
 791 {
 792         unsigned int off, num;
 793         const struct arpt_entry *e;
 794         struct xt_counters *counters;
 795         struct xt_table_info *private = table->private;
 796         int ret = 0;
 797         void *loc_cpu_entry;
 798
 799         counters = alloc_counters(table);
 800         if (IS_ERR(counters))
 801                 return PTR_ERR(counters);
 802
 803         loc_cpu_entry = private->entries;
 804         /* ... then copy entire thing ... */
 805         if (copy_to_user(userptr, loc_cpu_entry, total_size) != 0) {
 806                 ret = -EFAULT;
 807                 goto free_counters;
 808         }
 809
 810         /* FIXME: use iterator macros --RR */
 811         /* ... then go back and fix counters and names */
 812         for (off = 0, num = 0; off < total_size; off += e->next_offset, num++){
 813                 const struct xt_entry_target *t;
 814
 815                 e = (struct arpt_entry *)(loc_cpu_entry + off);
 816                 if (copy_to_user(userptr + off
 817                                  + offsetof(struct arpt_entry, counters),
 818                                  &counters[num],
 819                                  sizeof(counters[num])) != 0) {
 820                         ret = -EFAULT;
 821                         goto free_counters;
 822                 }
 823
 824                 t = arpt_get_target_c(e);
 825                 if (copy_to_user(userptr + off + e->target_offset
 826                                  + offsetof(struct xt_entry_target,
 827                                             u.user.name),
 828                                  t->u.kernel.target->name,
 829                                  strlen(t->u.kernel.target->name)+1) != 0) {
 830                         ret = -EFAULT;
 831                         goto free_counters;
 832                 }
 833         }
 834
 835  free_counters:
 836         vfree(counters);
 837         return ret;
 838 }
 839
 840 #ifdef CONFIG_COMPAT
 841 static void compat_standard_from_user(void *dst, const void *src)
 842 {
 843         int v = *(compat_int_t *)src;
 844
 845         if (v > 0)
 846                 v += xt_compat_calc_jump(NFPROTO_ARP, v);
 847         memcpy(dst, &v, sizeof(v));
 848 }
 849
 850 static int compat_standard_to_user(void __user *dst, const void *src)
 851 {
 852         compat_int_t cv = *(int *)src;
 853
 854         if (cv > 0)
 855                 cv -= xt_compat_calc_jump(NFPROTO_ARP, cv);
 856         return copy_to_user(dst, &cv, sizeof(cv)) ? -EFAULT : 0;
 857 }
 858
 859 static int compat_calc_entry(const struct arpt_entry *e,
 860                              const struct xt_table_info *info,
 861                              const void *base, struct xt_table_info *newinfo)
 862 {
 863         const struct xt_entry_target *t;
 864         unsigned int entry_offset;
 865         int off, i, ret;
 866
 867         off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
 868         entry_offset = (void *)e - base;
 869
 870         t = arpt_get_target_c(e);
 871         off += xt_compat_target_offset(t->u.kernel.target);
 872         newinfo->size -= off;
 873         ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
 874         if (ret)
 875                 return ret;
 876
 877         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
 878                 if (info->hook_entry[i] &&
 879                     (e < (struct arpt_entry *)(base + info->hook_entry[i])))
 880                         newinfo->hook_entry[i] -= off;
 881                 if (info->underflow[i] &&
 882                     (e < (struct arpt_entry *)(base + info->underflow[i])))
 883                         newinfo->underflow[i] -= off;
 884         }
 885         return 0;
 886 }
 887
 888 static int compat_table_info(const struct xt_table_info *info,
 889                              struct xt_table_info *newinfo)
 890 {
 891         struct arpt_entry *iter;
 892         const void *loc_cpu_entry;
 893         int ret;
 894
 895         if (!newinfo || !info)
 896                 return -EINVAL;
 897
 898         /* we dont care about newinfo->entries */
 899         memcpy(newinfo, info, offsetof(struct xt_table_info, entries));
 900         newinfo->initial_entries = 0;
 901         loc_cpu_entry = info->entries;
 902         xt_compat_init_offsets(NFPROTO_ARP, info->number);
 903         xt_entry_foreach(iter, loc_cpu_entry, info->size) {
 904                 ret = compat_calc_entry(iter, info, loc_cpu_entry, newinfo);
 905                 if (ret != 0)
 906                         return ret;
 907         }
 908         return 0;
 909 }
 910 #endif
 911
 912 static int get_info(struct net *net, void __user *user,
 913                     const int *len, int compat)
 914 {
 915         char name[XT_TABLE_MAXNAMELEN];
 916         struct xt_table *t;
 917         int ret;
 918
 919         if (*len != sizeof(struct arpt_getinfo)) {
 920                 duprintf("length %u != %Zu\n", *len,
 921                          sizeof(struct arpt_getinfo));
 922                 return -EINVAL;
 923         }
 924
 925         if (copy_from_user(name, user, sizeof(name)) != 0)
 926                 return -EFAULT;
 927
 928         name[XT_TABLE_MAXNAMELEN-1] = '\0';
 929 #ifdef CONFIG_COMPAT
 930         if (compat)
 931                 xt_compat_lock(NFPROTO_ARP);
 932 #endif
 933         t = try_then_request_module(xt_find_table_lock(net, NFPROTO_ARP, name),
 934                                     "arptable_%s", name);
 935         if (!IS_ERR_OR_NULL(t)) {
 936                 struct arpt_getinfo info;
 937                 const struct xt_table_info *private = t->private;
 938 #ifdef CONFIG_COMPAT
 939                 struct xt_table_info tmp;
 940
 941                 if (compat) {
 942                         ret = compat_table_info(private, &tmp);
 943                         xt_compat_flush_offsets(NFPROTO_ARP);
 944                         private = &tmp;
 945                 }
 946 #endif
 947                 memset(&info, 0, sizeof(info));
 948                 info.valid_hooks = t->valid_hooks;
 949                 memcpy(info.hook_entry, private->hook_entry,
 950                        sizeof(info.hook_entry));
 951                 memcpy(info.underflow, private->underflow,
 952                        sizeof(info.underflow));
 953                 info.num_entries = private->number;
 954                 info.size = private->size;
 955                 strcpy(info.name, name);
 956
 957                 if (copy_to_user(user, &info, *len) != 0)
 958                         ret = -EFAULT;
 959                 else
 960                         ret = 0;
 961                 xt_table_unlock(t);
 962                 module_put(t->me);
 963         } else
 964                 ret = t ? PTR_ERR(t) : -ENOENT;
 965 #ifdef CONFIG_COMPAT
 966         if (compat)
 967                 xt_compat_unlock(NFPROTO_ARP);
 968 #endif
 969         return ret;
 970 }
 971
 972 static int get_entries(struct net *net, struct arpt_get_entries __user *uptr,
 973                        const int *len)
 974 {
 975         int ret;
 976         struct arpt_get_entries get;
 977         struct xt_table *t;
 978
 979         if (*len < sizeof(get)) {
 980                 duprintf("get_entries: %u < %Zu\n", *len, sizeof(get));
 981                 return -EINVAL;
 982         }
 983         if (copy_from_user(&get, uptr, sizeof(get)) != 0)
 984                 return -EFAULT;
 985         if (*len != sizeof(struct arpt_get_entries) + get.size) {
 986                 duprintf("get_entries: %u != %Zu\n", *len,
 987                          sizeof(struct arpt_get_entries) + get.size);
 988                 return -EINVAL;
 989         }
 990         get.name[sizeof(get.name) - 1] = '\0';
 991
 992         t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
 993         if (!IS_ERR_OR_NULL(t)) {
 994                 const struct xt_table_info *private = t->private;
 995
 996                 duprintf("t->private->number = %u\n",
 997                          private->number);
 998                 if (get.size == private->size)
 999                         ret = copy_entries_to_user(private->size,
1000                                                    t, uptr->entrytable);
1001                 else {
1002                         duprintf("get_entries: I've got %u not %u!\n",
1003                                  private->size, get.size);
1004                         ret = -EAGAIN;
1005                 }
1006                 module_put(t->me);
1007                 xt_table_unlock(t);
1008         } else
1009                 ret = t ? PTR_ERR(t) : -ENOENT;
1010
1011         return ret;
1012 }
1013
1014 static int __do_replace(struct net *net, const char *name,
1015                         unsigned int valid_hooks,
1016                         struct xt_table_info *newinfo,
1017                         unsigned int num_counters,
1018                         void __user *counters_ptr)
1019 {
1020         int ret;
1021         struct xt_table *t;
1022         struct xt_table_info *oldinfo;
1023         struct xt_counters *counters;
1024         void *loc_cpu_old_entry;
1025         struct arpt_entry *iter;
1026
1027         ret = 0;
1028         counters = vzalloc(num_counters * sizeof(struct xt_counters));
1029         if (!counters) {
1030                 ret = -ENOMEM;
1031                 goto out;
1032         }
1033
1034         t = try_then_request_module(xt_find_table_lock(net, NFPROTO_ARP, name),
1035                                     "arptable_%s", name);
1036         if (IS_ERR_OR_NULL(t)) {
1037                 ret = t ? PTR_ERR(t) : -ENOENT;
1038                 goto free_newinfo_counters_untrans;
1039         }
1040
1041         /* You lied! */
1042         if (valid_hooks != t->valid_hooks) {
1043                 duprintf("Valid hook crap: %08X vs %08X\n",
1044                          valid_hooks, t->valid_hooks);
1045                 ret = -EINVAL;
1046                 goto put_module;
1047         }
1048
1049         oldinfo = xt_replace_table(t, num_counters, newinfo, &ret);
1050         if (!oldinfo)
1051                 goto put_module;
1052
1053         /* Update module usage count based on number of rules */
1054         duprintf("do_replace: oldnum=%u, initnum=%u, newnum=%u\n",
1055                 oldinfo->number, oldinfo->initial_entries, newinfo->number);
1056         if ((oldinfo->number > oldinfo->initial_entries) ||
1057             (newinfo->number <= oldinfo->initial_entries))
1058                 module_put(t->me);
1059         if ((oldinfo->number > oldinfo->initial_entries) &&
1060             (newinfo->number <= oldinfo->initial_entries))
1061                 module_put(t->me);
1062
1063         /* Get the old counters, and synchronize with replace */
1064         get_counters(oldinfo, counters);
1065
1066         /* Decrease module usage counts and free resource */
1067         loc_cpu_old_entry = oldinfo->entries;
1068         xt_entry_foreach(iter, loc_cpu_old_entry, oldinfo->size)
1069                 cleanup_entry(iter);
1070
1071         xt_free_table_info(oldinfo);
1072         if (copy_to_user(counters_ptr, counters,
1073                          sizeof(struct xt_counters) * num_counters) != 0) {
1074                 /* Silent error, can't fail, new table is already in place */
1075                 net_warn_ratelimited("arptables: counters copy to user failed while replacing table\n");
1076         }
1077         vfree(counters);
1078         xt_table_unlock(t);
1079         return ret;
1080
1081  put_module:
1082         module_put(t->me);
1083         xt_table_unlock(t);
1084  free_newinfo_counters_untrans:
1085         vfree(counters);
1086  out:
1087         return ret;
1088 }
1089
1090 static int do_replace(struct net *net, const void __user *user,
1091                       unsigned int len)
1092 {
1093         int ret;
1094         struct arpt_replace tmp;
1095         struct xt_table_info *newinfo;
1096         void *loc_cpu_entry;
1097         struct arpt_entry *iter;
1098
1099         if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
1100                 return -EFAULT;
1101
1102         /* overflow check */
1103         if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
1104                 return -ENOMEM;
1105         if (tmp.num_counters == 0)
1106                 return -EINVAL;
1107
1108         tmp.name[sizeof(tmp.name)-1] = 0;
1109
1110         newinfo = xt_alloc_table_info(tmp.size);
1111         if (!newinfo)
1112                 return -ENOMEM;
1113
1114         loc_cpu_entry = newinfo->entries;
1115         if (copy_from_user(loc_cpu_entry, user + sizeof(tmp),
1116                            tmp.size) != 0) {
1117                 ret = -EFAULT;
1118                 goto free_newinfo;
1119         }
1120
1121         ret = translate_table(newinfo, loc_cpu_entry, &tmp);
1122         if (ret != 0)
1123                 goto free_newinfo;
1124
1125         duprintf("arp_tables: Translated table\n");
1126
1127         ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
1128                            tmp.num_counters, tmp.counters);
1129         if (ret)
1130                 goto free_newinfo_untrans;
1131         return 0;
1132
1133  free_newinfo_untrans:
1134         xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
1135                 cleanup_entry(iter);
1136  free_newinfo:
1137         xt_free_table_info(newinfo);
1138         return ret;
1139 }
1140
1141 static int do_add_counters(struct net *net, const void __user *user,
1142                            unsigned int len, int compat)
1143 {
1144         unsigned int i;
1145         struct xt_counters_info tmp;
1146         struct xt_counters *paddc;
1147         unsigned int num_counters;
1148         const char *name;
1149         int size;
1150         void *ptmp;
1151         struct xt_table *t;
1152         const struct xt_table_info *private;
1153         int ret = 0;
1154         struct arpt_entry *iter;
1155         unsigned int addend;
1156 #ifdef CONFIG_COMPAT
1157         struct compat_xt_counters_info compat_tmp;
1158
1159         if (compat) {
1160                 ptmp = &compat_tmp;
1161                 size = sizeof(struct compat_xt_counters_info);
1162         } else
1163 #endif
1164         {
1165                 ptmp = &tmp;
1166                 size = sizeof(struct xt_counters_info);
1167         }
1168
1169         if (copy_from_user(ptmp, user, size) != 0)
1170                 return -EFAULT;
1171
1172 #ifdef CONFIG_COMPAT
1173         if (compat) {
1174                 num_counters = compat_tmp.num_counters;
1175                 name = compat_tmp.name;
1176         } else
1177 #endif
1178         {
1179                 num_counters = tmp.num_counters;
1180                 name = tmp.name;
1181         }
1182
1183         if (len != size + num_counters * sizeof(struct xt_counters))
1184                 return -EINVAL;
1185
1186         paddc = vmalloc(len - size);
1187         if (!paddc)
1188                 return -ENOMEM;
1189
1190         if (copy_from_user(paddc, user + size, len - size) != 0) {
1191                 ret = -EFAULT;
1192                 goto free;
1193         }
1194
1195         t = xt_find_table_lock(net, NFPROTO_ARP, name);
1196         if (IS_ERR_OR_NULL(t)) {
1197                 ret = t ? PTR_ERR(t) : -ENOENT;
1198                 goto free;
1199         }
1200
1201         local_bh_disable();
1202         private = t->private;
1203         if (private->number != num_counters) {
1204                 ret = -EINVAL;
1205                 goto unlock_up_free;
1206         }
1207
1208         i = 0;
1209
1210         addend = xt_write_recseq_begin();
1211         xt_entry_foreach(iter,  private->entries, private->size) {
1212                 struct xt_counters *tmp;
1213
1214                 tmp = xt_get_this_cpu_counter(&iter->counters);
1215                 ADD_COUNTER(*tmp, paddc[i].bcnt, paddc[i].pcnt);
1216                 ++i;
1217         }
1218         xt_write_recseq_end(addend);
1219  unlock_up_free:
1220         local_bh_enable();
1221         xt_table_unlock(t);
1222         module_put(t->me);
1223  free:
1224         vfree(paddc);
1225
1226         return ret;
1227 }
1228
1229 #ifdef CONFIG_COMPAT
1230 static inline void compat_release_entry(struct compat_arpt_entry *e)
1231 {
1232         struct xt_entry_target *t;
1233
1234         t = compat_arpt_get_target(e);
1235         module_put(t->u.kernel.target->me);
1236 }
1237
1238 static inline int
1239 check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
1240                                   struct xt_table_info *newinfo,
1241                                   unsigned int *size,
1242                                   const unsigned char *base,
1243                                   const unsigned char *limit,
1244                                   const unsigned int *hook_entries,
1245                                   const unsigned int *underflows,
1246                                   const char *name)
1247 {
1248         struct xt_entry_target *t;
1249         struct xt_target *target;
1250         unsigned int entry_offset;
1251         int ret, off, h;
1252
1253         duprintf("check_compat_entry_size_and_hooks %p\n", e);
1254         if ((unsigned long)e % __alignof__(struct compat_arpt_entry) != 0 ||
1255             (unsigned char *)e + sizeof(struct compat_arpt_entry) >= limit ||
1256             (unsigned char *)e + e->next_offset > limit) {
1257                 duprintf("Bad offset %p, limit = %p\n", e, limit);
1258                 return -EINVAL;
1259         }
1260
1261         if (e->next_offset < sizeof(struct compat_arpt_entry) +
1262                              sizeof(struct compat_xt_entry_target)) {
1263                 duprintf("checking: element %p size %u\n",
1264                          e, e->next_offset);
1265                 return -EINVAL;
1266         }
1267
1268         /* For purposes of check_entry casting the compat entry is fine */
1269         ret = check_entry((struct arpt_entry *)e);
1270         if (ret)
1271                 return ret;
1272
1273         off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1274         entry_offset = (void *)e - (void *)base;
1275
1276         t = compat_arpt_get_target(e);
1277         target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
1278                                         t->u.user.revision);
1279         if (IS_ERR(target)) {
1280                 duprintf("check_compat_entry_size_and_hooks: `%s' not found\n",
1281                          t->u.user.name);
1282                 ret = PTR_ERR(target);
1283                 goto out;
1284         }
1285         t->u.kernel.target = target;
1286
1287         off += xt_compat_target_offset(target);
1288         *size += off;
1289         ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
1290         if (ret)
1291                 goto release_target;
1292
1293         /* Check hooks & underflows */
1294         for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
1295                 if ((unsigned char *)e - base == hook_entries[h])
1296                         newinfo->hook_entry[h] = hook_entries[h];
1297                 if ((unsigned char *)e - base == underflows[h])
1298                         newinfo->underflow[h] = underflows[h];
1299         }
1300
1301         /* Clear counters and comefrom */
1302         memset(&e->counters, 0, sizeof(e->counters));
1303         e->comefrom = 0;
1304         return 0;
1305
1306 release_target:
1307         module_put(t->u.kernel.target->me);
1308 out:
1309         return ret;
1310 }
1311
1312 static int
1313 compat_copy_entry_from_user(struct compat_arpt_entry *e, void **dstptr,
1314                             unsigned int *size, const char *name,
1315                             struct xt_table_info *newinfo, unsigned char *base)
1316 {
1317         struct xt_entry_target *t;
1318         struct xt_target *target;
1319         struct arpt_entry *de;
1320         unsigned int origsize;
1321         int ret, h;
1322
1323         ret = 0;
1324         origsize = *size;
1325         de = (struct arpt_entry *)*dstptr;
1326         memcpy(de, e, sizeof(struct arpt_entry));
1327         memcpy(&de->counters, &e->counters, sizeof(e->counters));
1328
1329         *dstptr += sizeof(struct arpt_entry);
1330         *size += sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1331
1332         de->target_offset = e->target_offset - (origsize - *size);
1333         t = compat_arpt_get_target(e);
1334         target = t->u.kernel.target;
1335         xt_compat_target_from_user(t, dstptr, size);
1336
1337         de->next_offset = e->next_offset - (origsize - *size);
1338         for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
1339                 if ((unsigned char *)de - base < newinfo->hook_entry[h])
1340                         newinfo->hook_entry[h] -= origsize - *size;
1341                 if ((unsigned char *)de - base < newinfo->underflow[h])
1342                         newinfo->underflow[h] -= origsize - *size;
1343         }
1344         return ret;
1345 }
1346
1347 static int translate_compat_table(const char *name,
1348                                   unsigned int valid_hooks,
1349                                   struct xt_table_info **pinfo,
1350                                   void **pentry0,
1351                                   unsigned int total_size,
1352                                   unsigned int number,
1353                                   unsigned int *hook_entries,
1354                                   unsigned int *underflows)
1355 {
1356         unsigned int i, j;
1357         struct xt_table_info *newinfo, *info;
1358         void *pos, *entry0, *entry1;
1359         struct compat_arpt_entry *iter0;
1360         struct arpt_entry *iter1;
1361         unsigned int size;
1362         int ret = 0;
1363
1364         info = *pinfo;
1365         entry0 = *pentry0;
1366         size = total_size;
1367         info->number = number;
1368
1369         /* Init all hooks to impossible value. */
1370         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1371                 info->hook_entry[i] = 0xFFFFFFFF;
1372                 info->underflow[i] = 0xFFFFFFFF;
1373         }
1374
1375         duprintf("translate_compat_table: size %u\n", info->size);
1376         j = 0;
1377         xt_compat_lock(NFPROTO_ARP);
1378         xt_compat_init_offsets(NFPROTO_ARP, number);
1379         /* Walk through entries, checking offsets. */
1380         xt_entry_foreach(iter0, entry0, total_size) {
1381                 ret = check_compat_entry_size_and_hooks(iter0, info, &size,
1382                                                         entry0,
1383                                                         entry0 + total_size,
1384                                                         hook_entries,
1385                                                         underflows,
1386                                                         name);
1387                 if (ret != 0)
1388                         goto out_unlock;
1389                 ++j;
1390         }
1391
1392         ret = -EINVAL;
1393         if (j != number) {
1394                 duprintf("translate_compat_table: %u not %u entries\n",
1395                          j, number);
1396                 goto out_unlock;
1397         }
1398
1399         /* Check hooks all assigned */
1400         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1401                 /* Only hooks which are valid */
1402                 if (!(valid_hooks & (1 << i)))
1403                         continue;
1404                 if (info->hook_entry[i] == 0xFFFFFFFF) {
1405                         duprintf("Invalid hook entry %u %u\n",
1406                                  i, hook_entries[i]);
1407                         goto out_unlock;
1408                 }
1409                 if (info->underflow[i] == 0xFFFFFFFF) {
1410                         duprintf("Invalid underflow %u %u\n",
1411                                  i, underflows[i]);
1412                         goto out_unlock;
1413                 }
1414         }
1415
1416         ret = -ENOMEM;
1417         newinfo = xt_alloc_table_info(size);
1418         if (!newinfo)
1419                 goto out_unlock;
1420
1421         newinfo->number = number;
1422         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1423                 newinfo->hook_entry[i] = info->hook_entry[i];
1424                 newinfo->underflow[i] = info->underflow[i];
1425         }
1426         entry1 = newinfo->entries;
1427         pos = entry1;
1428         size = total_size;
1429         xt_entry_foreach(iter0, entry0, total_size) {
1430                 ret = compat_copy_entry_from_user(iter0, &pos, &size,
1431                                                   name, newinfo, entry1);
1432                 if (ret != 0)
1433                         break;
1434         }
1435         xt_compat_flush_offsets(NFPROTO_ARP);
1436         xt_compat_unlock(NFPROTO_ARP);
1437         if (ret)
1438                 goto free_newinfo;
1439
1440         ret = -ELOOP;
1441         if (!mark_source_chains(newinfo, valid_hooks, entry1))
1442                 goto free_newinfo;
1443
1444         i = 0;
1445         xt_entry_foreach(iter1, entry1, newinfo->size) {
1446                 iter1->counters.pcnt = xt_percpu_counter_alloc();
1447                 if (IS_ERR_VALUE(iter1->counters.pcnt)) {
1448                         ret = -ENOMEM;
1449                         break;
1450                 }
1451
1452                 ret = check_target(iter1, name);
1453                 if (ret != 0) {
1454                         xt_percpu_counter_free(iter1->counters.pcnt);
1455                         break;
1456                 }
1457                 ++i;
1458                 if (strcmp(arpt_get_target(iter1)->u.user.name,
1459                     XT_ERROR_TARGET) == 0)
1460                         ++newinfo->stacksize;
1461         }
1462         if (ret) {
1463                 /*
1464                  * The first i matches need cleanup_entry (calls ->destroy)
1465                  * because they had called ->check already. The other j-i
1466                  * entries need only release.
1467                  */
1468                 int skip = i;
1469                 j -= i;
1470                 xt_entry_foreach(iter0, entry0, newinfo->size) {
1471                         if (skip-- > 0)
1472                                 continue;
1473                         if (j-- == 0)
1474                                 break;
1475                         compat_release_entry(iter0);
1476                 }
1477                 xt_entry_foreach(iter1, entry1, newinfo->size) {
1478                         if (i-- == 0)
1479                                 break;
1480                         cleanup_entry(iter1);
1481                 }
1482                 xt_free_table_info(newinfo);
1483                 return ret;
1484         }
1485
1486         *pinfo = newinfo;
1487         *pentry0 = entry1;
1488         xt_free_table_info(info);
1489         return 0;
1490
1491 free_newinfo:
1492         xt_free_table_info(newinfo);
1493 out:
1494         xt_entry_foreach(iter0, entry0, total_size) {
1495                 if (j-- == 0)
1496                         break;
1497                 compat_release_entry(iter0);
1498         }
1499         return ret;
1500 out_unlock:
1501         xt_compat_flush_offsets(NFPROTO_ARP);
1502         xt_compat_unlock(NFPROTO_ARP);
1503         goto out;
1504 }
1505
1506 struct compat_arpt_replace {
1507         char                            name[XT_TABLE_MAXNAMELEN];
1508         u32                             valid_hooks;
1509         u32                             num_entries;
1510         u32                             size;
1511         u32                             hook_entry[NF_ARP_NUMHOOKS];
1512         u32                             underflow[NF_ARP_NUMHOOKS];
1513         u32                             num_counters;
1514         compat_uptr_t                   counters;
1515         struct compat_arpt_entry        entries[0];
1516 };
1517
1518 static int compat_do_replace(struct net *net, void __user *user,
1519                              unsigned int len)
1520 {
1521         int ret;
1522         struct compat_arpt_replace tmp;
1523         struct xt_table_info *newinfo;
1524         void *loc_cpu_entry;
1525         struct arpt_entry *iter;
1526
1527         if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
1528                 return -EFAULT;
1529
1530         /* overflow check */
1531         if (tmp.size >= INT_MAX / num_possible_cpus())
1532                 return -ENOMEM;
1533         if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
1534                 return -ENOMEM;
1535         if (tmp.num_counters == 0)
1536                 return -EINVAL;
1537
1538         tmp.name[sizeof(tmp.name)-1] = 0;
1539
1540         newinfo = xt_alloc_table_info(tmp.size);
1541         if (!newinfo)
1542                 return -ENOMEM;
1543
1544         loc_cpu_entry = newinfo->entries;
1545         if (copy_from_user(loc_cpu_entry, user + sizeof(tmp), tmp.size) != 0) {
1546                 ret = -EFAULT;
1547                 goto free_newinfo;
1548         }
1549
1550         ret = translate_compat_table(tmp.name, tmp.valid_hooks,
1551                                      &newinfo, &loc_cpu_entry, tmp.size,
1552                                      tmp.num_entries, tmp.hook_entry,
1553                                      tmp.underflow);
1554         if (ret != 0)
1555                 goto free_newinfo;
1556
1557         duprintf("compat_do_replace: Translated table\n");
1558
1559         ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
1560                            tmp.num_counters, compat_ptr(tmp.counters));
1561         if (ret)
1562                 goto free_newinfo_untrans;
1563         return 0;
1564
1565  free_newinfo_untrans:
1566         xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
1567                 cleanup_entry(iter);
1568  free_newinfo:
1569         xt_free_table_info(newinfo);
1570         return ret;
1571 }
1572
1573 static int compat_do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user,
1574                                   unsigned int len)
1575 {
1576         int ret;
1577
1578         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1579                 return -EPERM;
1580
1581         switch (cmd) {
1582         case ARPT_SO_SET_REPLACE:
1583                 ret = compat_do_replace(sock_net(sk), user, len);
1584                 break;
1585
1586         case ARPT_SO_SET_ADD_COUNTERS:
1587                 ret = do_add_counters(sock_net(sk), user, len, 1);
1588                 break;
1589
1590         default:
1591                 duprintf("do_arpt_set_ctl:  unknown request %i\n", cmd);
1592                 ret = -EINVAL;
1593         }
1594
1595         return ret;
1596 }
1597
1598 static int compat_copy_entry_to_user(struct arpt_entry *e, void __user **dstptr,
1599                                      compat_uint_t *size,
1600                                      struct xt_counters *counters,
1601                                      unsigned int i)
1602 {
1603         struct xt_entry_target *t;
1604         struct compat_arpt_entry __user *ce;
1605         u_int16_t target_offset, next_offset;
1606         compat_uint_t origsize;
1607         int ret;
1608
1609         origsize = *size;
1610         ce = (struct compat_arpt_entry __user *)*dstptr;
1611         if (copy_to_user(ce, e, sizeof(struct arpt_entry)) != 0 ||
1612             copy_to_user(&ce->counters, &counters[i],
1613             sizeof(counters[i])) != 0)
1614                 return -EFAULT;
1615
1616         *dstptr += sizeof(struct compat_arpt_entry);
1617         *size -= sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1618
1619         target_offset = e->target_offset - (origsize - *size);
1620
1621         t = arpt_get_target(e);
1622         ret = xt_compat_target_to_user(t, dstptr, size);
1623         if (ret)
1624                 return ret;
1625         next_offset = e->next_offset - (origsize - *size);
1626         if (put_user(target_offset, &ce->target_offset) != 0 ||
1627             put_user(next_offset, &ce->next_offset) != 0)
1628                 return -EFAULT;
1629         return 0;
1630 }
1631
1632 static int compat_copy_entries_to_user(unsigned int total_size,
1633                                        struct xt_table *table,
1634                                        void __user *userptr)
1635 {
1636         struct xt_counters *counters;
1637         const struct xt_table_info *private = table->private;
1638         void __user *pos;
1639         unsigned int size;
1640         int ret = 0;
1641         unsigned int i = 0;
1642         struct arpt_entry *iter;
1643
1644         counters = alloc_counters(table);
1645         if (IS_ERR(counters))
1646                 return PTR_ERR(counters);
1647
1648         pos = userptr;
1649         size = total_size;
1650         xt_entry_foreach(iter, private->entries, total_size) {
1651                 ret = compat_copy_entry_to_user(iter, &pos,
1652                                                 &size, counters, i++);
1653                 if (ret != 0)
1654                         break;
1655         }
1656         vfree(counters);
1657         return ret;
1658 }
1659
1660 struct compat_arpt_get_entries {
1661         char name[XT_TABLE_MAXNAMELEN];
1662         compat_uint_t size;
1663         struct compat_arpt_entry entrytable[0];
1664 };
1665
1666 static int compat_get_entries(struct net *net,
1667                               struct compat_arpt_get_entries __user *uptr,
1668                               int *len)
1669 {
1670         int ret;
1671         struct compat_arpt_get_entries get;
1672         struct xt_table *t;
1673
1674         if (*len < sizeof(get)) {
1675                 duprintf("compat_get_entries: %u < %zu\n", *len, sizeof(get));
1676                 return -EINVAL;
1677         }
1678         if (copy_from_user(&get, uptr, sizeof(get)) != 0)
1679                 return -EFAULT;
1680         if (*len != sizeof(struct compat_arpt_get_entries) + get.size) {
1681                 duprintf("compat_get_entries: %u != %zu\n",
1682                          *len, sizeof(get) + get.size);
1683                 return -EINVAL;
1684         }
1685         get.name[sizeof(get.name) - 1] = '\0';
1686
1687         xt_compat_lock(NFPROTO_ARP);
1688         t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
1689         if (!IS_ERR_OR_NULL(t)) {
1690                 const struct xt_table_info *private = t->private;
1691                 struct xt_table_info info;
1692
1693                 duprintf("t->private->number = %u\n", private->number);
1694                 ret = compat_table_info(private, &info);
1695                 if (!ret && get.size == info.size) {
1696                         ret = compat_copy_entries_to_user(private->size,
1697                                                           t, uptr->entrytable);
1698                 } else if (!ret) {
1699                         duprintf("compat_get_entries: I've got %u not %u!\n",
1700                                  private->size, get.size);
1701                         ret = -EAGAIN;
1702                 }
1703                 xt_compat_flush_offsets(NFPROTO_ARP);
1704                 module_put(t->me);
1705                 xt_table_unlock(t);
1706         } else
1707                 ret = t ? PTR_ERR(t) : -ENOENT;
1708
1709         xt_compat_unlock(NFPROTO_ARP);
1710         return ret;
1711 }
1712
1713 static int do_arpt_get_ctl(struct sock *, int, void __user *, int *);
1714
1715 static int compat_do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user,
1716                                   int *len)
1717 {
1718         int ret;
1719
1720         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1721                 return -EPERM;
1722
1723         switch (cmd) {
1724         case ARPT_SO_GET_INFO:
1725                 ret = get_info(sock_net(sk), user, len, 1);
1726                 break;
1727         case ARPT_SO_GET_ENTRIES:
1728                 ret = compat_get_entries(sock_net(sk), user, len);
1729                 break;
1730         default:
1731                 ret = do_arpt_get_ctl(sk, cmd, user, len);
1732         }
1733         return ret;
1734 }
1735 #endif
1736
1737 static int do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
1738 {
1739         int ret;
1740
1741         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1742                 return -EPERM;
1743
1744         switch (cmd) {
1745         case ARPT_SO_SET_REPLACE:
1746                 ret = do_replace(sock_net(sk), user, len);
1747                 break;
1748
1749         case ARPT_SO_SET_ADD_COUNTERS:
1750                 ret = do_add_counters(sock_net(sk), user, len, 0);
1751                 break;
1752
1753         default:
1754                 duprintf("do_arpt_set_ctl:  unknown request %i\n", cmd);
1755                 ret = -EINVAL;
1756         }
1757
1758         return ret;
1759 }
1760
1761 static int do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
1762 {
1763         int ret;
1764
1765         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1766                 return -EPERM;
1767
1768         switch (cmd) {
1769         case ARPT_SO_GET_INFO:
1770                 ret = get_info(sock_net(sk), user, len, 0);
1771                 break;
1772
1773         case ARPT_SO_GET_ENTRIES:
1774                 ret = get_entries(sock_net(sk), user, len);
1775                 break;
1776
1777         case ARPT_SO_GET_REVISION_TARGET: {
1778                 struct xt_get_revision rev;
1779
1780                 if (*len != sizeof(rev)) {
1781                         ret = -EINVAL;
1782                         break;
1783                 }
1784                 if (copy_from_user(&rev, user, sizeof(rev)) != 0) {
1785                         ret = -EFAULT;
1786                         break;
1787                 }
1788                 rev.name[sizeof(rev.name)-1] = 0;
1789
1790                 try_then_request_module(xt_find_revision(NFPROTO_ARP, rev.name,
1791                                                          rev.revision, 1, &ret),
1792                                         "arpt_%s", rev.name);
1793                 break;
1794         }
1795
1796         default:
1797                 duprintf("do_arpt_get_ctl: unknown request %i\n", cmd);
1798                 ret = -EINVAL;
1799         }
1800
1801         return ret;
1802 }
1803
1804 static void __arpt_unregister_table(struct xt_table *table)
1805 {
1806         struct xt_table_info *private;
1807         void *loc_cpu_entry;
1808         struct module *table_owner = table->me;
1809         struct arpt_entry *iter;
1810
1811         private = xt_unregister_table(table);
1812
1813         /* Decrease module usage counts and free resources */
1814         loc_cpu_entry = private->entries;
1815         xt_entry_foreach(iter, loc_cpu_entry, private->size)
1816                 cleanup_entry(iter);
1817         if (private->number > private->initial_entries)
1818                 module_put(table_owner);
1819         xt_free_table_info(private);
1820 }
1821
1822 int arpt_register_table(struct net *net,
1823                         const struct xt_table *table,
1824                         const struct arpt_replace *repl,
1825                         const struct nf_hook_ops *ops,
1826                         struct xt_table **res)
1827 {
1828         int ret;
1829         struct xt_table_info *newinfo;
1830         struct xt_table_info bootstrap = {0};
1831         void *loc_cpu_entry;
1832         struct xt_table *new_table;
1833
1834         newinfo = xt_alloc_table_info(repl->size);
1835         if (!newinfo)
1836                 return -ENOMEM;
1837
1838         loc_cpu_entry = newinfo->entries;
1839         memcpy(loc_cpu_entry, repl->entries, repl->size);
1840
1841         ret = translate_table(newinfo, loc_cpu_entry, repl);
1842         duprintf("arpt_register_table: translate table gives %d\n", ret);
1843         if (ret != 0)
1844                 goto out_free;
1845
1846         new_table = xt_register_table(net, table, &bootstrap, newinfo);
1847         if (IS_ERR(new_table)) {
1848                 ret = PTR_ERR(new_table);
1849                 goto out_free;
1850         }
1851
1852         /* set res now, will see skbs right after nf_register_net_hooks */
1853         WRITE_ONCE(*res, new_table);
1854
1855         ret = nf_register_net_hooks(net, ops, hweight32(table->valid_hooks));
1856         if (ret != 0) {
1857                 __arpt_unregister_table(new_table);
1858                 *res = NULL;
1859         }
1860
1861         return ret;
1862
1863 out_free:
1864         xt_free_table_info(newinfo);
1865         return ret;
1866 }
1867
1868 void arpt_unregister_table(struct net *net, struct xt_table *table,
1869                            const struct nf_hook_ops *ops)
1870 {
1871         nf_unregister_net_hooks(net, ops, hweight32(table->valid_hooks));
1872         __arpt_unregister_table(table);
1873 }
1874
1875 /* The built-in targets: standard (NULL) and error. */
1876 static struct xt_target arpt_builtin_tg[] __read_mostly = {
1877         {
1878                 .name             = XT_STANDARD_TARGET,
1879                 .targetsize       = sizeof(int),
1880                 .family           = NFPROTO_ARP,
1881 #ifdef CONFIG_COMPAT
1882                 .compatsize       = sizeof(compat_int_t),
1883                 .compat_from_user = compat_standard_from_user,
1884                 .compat_to_user   = compat_standard_to_user,
1885 #endif
1886         },
1887         {
1888                 .name             = XT_ERROR_TARGET,
1889                 .target           = arpt_error,
1890                 .targetsize       = XT_FUNCTION_MAXNAMELEN,
1891                 .family           = NFPROTO_ARP,
1892         },
1893 };
1894
1895 static struct nf_sockopt_ops arpt_sockopts = {
1896         .pf             = PF_INET,
1897         .set_optmin     = ARPT_BASE_CTL,
1898         .set_optmax     = ARPT_SO_SET_MAX+1,
1899         .set            = do_arpt_set_ctl,
1900 #ifdef CONFIG_COMPAT
1901         .compat_set     = compat_do_arpt_set_ctl,
1902 #endif
1903         .get_optmin     = ARPT_BASE_CTL,
1904         .get_optmax     = ARPT_SO_GET_MAX+1,
1905         .get            = do_arpt_get_ctl,
1906 #ifdef CONFIG_COMPAT
1907         .compat_get     = compat_do_arpt_get_ctl,
1908 #endif
1909         .owner          = THIS_MODULE,
1910 };
1911
1912 static int __net_init arp_tables_net_init(struct net *net)
1913 {
1914         return xt_proto_init(net, NFPROTO_ARP);
1915 }
1916
1917 static void __net_exit arp_tables_net_exit(struct net *net)
1918 {
1919         xt_proto_fini(net, NFPROTO_ARP);
1920 }
1921
1922 static struct pernet_operations arp_tables_net_ops = {
1923         .init = arp_tables_net_init,
1924         .exit = arp_tables_net_exit,
1925 };
1926
1927 static int __init arp_tables_init(void)
1928 {
1929         int ret;
1930
1931         ret = register_pernet_subsys(&arp_tables_net_ops);
1932         if (ret < 0)
1933                 goto err1;
1934
1935         /* No one else will be downing sem now, so we won't sleep */
1936         ret = xt_register_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1937         if (ret < 0)
1938                 goto err2;
1939
1940         /* Register setsockopt */
1941         ret = nf_register_sockopt(&arpt_sockopts);
1942         if (ret < 0)
1943                 goto err4;
1944
1945         pr_info("arp_tables: (C) 2002 David S. Miller\n");
1946         return 0;
1947
1948 err4:
1949         xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1950 err2:
1951         unregister_pernet_subsys(&arp_tables_net_ops);
1952 err1:
1953         return ret;
1954 }
1955
1956 static void __exit arp_tables_fini(void)
1957 {
1958         nf_unregister_sockopt(&arpt_sockopts);
1959         xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1960         unregister_pernet_subsys(&arp_tables_net_ops);
1961 }
1962
1963 EXPORT_SYMBOL(arpt_register_table);
1964 EXPORT_SYMBOL(arpt_unregister_table);
1965 EXPORT_SYMBOL(arpt_do_table);
1966
1967 module_init(arp_tables_init);
1968 module_exit(arp_tables_fini);