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 /* Figures out from what hook each rule can be called: returns 0 if
 371  * there are loops.  Puts hook bitmask in comefrom.
 372  */
 373 static int mark_source_chains(const struct xt_table_info *newinfo,
 374                               unsigned int valid_hooks, void *entry0)
 375 {
 376         unsigned int hook;
 377
 378         /* No recursion; use packet counter to save back ptrs (reset
 379          * to 0 as we leave), and comefrom to save source hook bitmask.
 380          */
 381         for (hook = 0; hook < NF_ARP_NUMHOOKS; hook++) {
 382                 unsigned int pos = newinfo->hook_entry[hook];
 383                 struct arpt_entry *e
 384                         = (struct arpt_entry *)(entry0 + pos);
 385
 386                 if (!(valid_hooks & (1 << hook)))
 387                         continue;
 388
 389                 /* Set initial back pointer. */
 390                 e->counters.pcnt = pos;
 391
 392                 for (;;) {
 393                         const struct xt_standard_target *t
 394                                 = (void *)arpt_get_target_c(e);
 395                         int visited = e->comefrom & (1 << hook);
 396
 397                         if (e->comefrom & (1 << NF_ARP_NUMHOOKS)) {
 398                                 pr_notice("arptables: loop hook %u pos %u %08X.\n",
 399                                        hook, pos, e->comefrom);
 400                                 return 0;
 401                         }
 402                         e->comefrom
 403                                 |= ((1 << hook) | (1 << NF_ARP_NUMHOOKS));
 404
 405                         /* Unconditional return/END. */
 406                         if ((unconditional(e) &&
 407                              (strcmp(t->target.u.user.name,
 408                                      XT_STANDARD_TARGET) == 0) &&
 409                              t->verdict < 0) || visited) {
 410                                 unsigned int oldpos, size;
 411
 412                                 if ((strcmp(t->target.u.user.name,
 413                                             XT_STANDARD_TARGET) == 0) &&
 414                                     t->verdict < -NF_MAX_VERDICT - 1) {
 415                                         duprintf("mark_source_chains: bad "
 416                                                 "negative verdict (%i)\n",
 417                                                                 t->verdict);
 418                                         return 0;
 419                                 }
 420
 421                                 /* Return: backtrack through the last
 422                                  * big jump.
 423                                  */
 424                                 do {
 425                                         e->comefrom ^= (1<<NF_ARP_NUMHOOKS);
 426                                         oldpos = pos;
 427                                         pos = e->counters.pcnt;
 428                                         e->counters.pcnt = 0;
 429
 430                                         /* We're at the start. */
 431                                         if (pos == oldpos)
 432                                                 goto next;
 433
 434                                         e = (struct arpt_entry *)
 435                                                 (entry0 + pos);
 436                                 } while (oldpos == pos + e->next_offset);
 437
 438                                 /* Move along one */
 439                                 size = e->next_offset;
 440                                 e = (struct arpt_entry *)
 441                                         (entry0 + pos + size);
 442                                 e->counters.pcnt = pos;
 443                                 pos += size;
 444                         } else {
 445                                 int newpos = t->verdict;
 446
 447                                 if (strcmp(t->target.u.user.name,
 448                                            XT_STANDARD_TARGET) == 0 &&
 449                                     newpos >= 0) {
 450                                         if (newpos > newinfo->size -
 451                                                 sizeof(struct arpt_entry)) {
 452                                                 duprintf("mark_source_chains: "
 453                                                         "bad verdict (%i)\n",
 454                                                                 newpos);
 455                                                 return 0;
 456                                         }
 457
 458                                         /* This a jump; chase it. */
 459                                         duprintf("Jump rule %u -> %u\n",
 460                                                  pos, newpos);
 461                                 } else {
 462                                         /* ... this is a fallthru */
 463                                         newpos = pos + e->next_offset;
 464                                 }
 465                                 e = (struct arpt_entry *)
 466                                         (entry0 + newpos);
 467                                 e->counters.pcnt = pos;
 468                                 pos = newpos;
 469                         }
 470                 }
 471 next:
 472                 duprintf("Finished chain %u\n", hook);
 473         }
 474         return 1;
 475 }
 476
 477 static inline int check_entry(const struct arpt_entry *e)
 478 {
 479         const struct xt_entry_target *t;
 480
 481         if (!arp_checkentry(&e->arp))
 482                 return -EINVAL;
 483
 484         if (e->target_offset + sizeof(struct xt_entry_target) > e->next_offset)
 485                 return -EINVAL;
 486
 487         t = arpt_get_target_c(e);
 488         if (e->target_offset + t->u.target_size > e->next_offset)
 489                 return -EINVAL;
 490
 491         return 0;
 492 }
 493
 494 static inline int check_target(struct arpt_entry *e, const char *name)
 495 {
 496         struct xt_entry_target *t = arpt_get_target(e);
 497         int ret;
 498         struct xt_tgchk_param par = {
 499                 .table     = name,
 500                 .entryinfo = e,
 501                 .target    = t->u.kernel.target,
 502                 .targinfo  = t->data,
 503                 .hook_mask = e->comefrom,
 504                 .family    = NFPROTO_ARP,
 505         };
 506
 507         ret = xt_check_target(&par, t->u.target_size - sizeof(*t), 0, false);
 508         if (ret < 0) {
 509                 duprintf("arp_tables: check failed for `%s'.\n",
 510                          t->u.kernel.target->name);
 511                 return ret;
 512         }
 513         return 0;
 514 }
 515
 516 static inline int
 517 find_check_entry(struct arpt_entry *e, const char *name, unsigned int size)
 518 {
 519         struct xt_entry_target *t;
 520         struct xt_target *target;
 521         int ret;
 522
 523         e->counters.pcnt = xt_percpu_counter_alloc();
 524         if (IS_ERR_VALUE(e->counters.pcnt))
 525                 return -ENOMEM;
 526
 527         t = arpt_get_target(e);
 528         target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
 529                                         t->u.user.revision);
 530         if (IS_ERR(target)) {
 531                 duprintf("find_check_entry: `%s' not found\n", t->u.user.name);
 532                 ret = PTR_ERR(target);
 533                 goto out;
 534         }
 535         t->u.kernel.target = target;
 536
 537         ret = check_target(e, name);
 538         if (ret)
 539                 goto err;
 540         return 0;
 541 err:
 542         module_put(t->u.kernel.target->me);
 543 out:
 544         xt_percpu_counter_free(e->counters.pcnt);
 545
 546         return ret;
 547 }
 548
 549 static bool check_underflow(const struct arpt_entry *e)
 550 {
 551         const struct xt_entry_target *t;
 552         unsigned int verdict;
 553
 554         if (!unconditional(e))
 555                 return false;
 556         t = arpt_get_target_c(e);
 557         if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
 558                 return false;
 559         verdict = ((struct xt_standard_target *)t)->verdict;
 560         verdict = -verdict - 1;
 561         return verdict == NF_DROP || verdict == NF_ACCEPT;
 562 }
 563
 564 static inline int check_entry_size_and_hooks(struct arpt_entry *e,
 565                                              struct xt_table_info *newinfo,
 566                                              const unsigned char *base,
 567                                              const unsigned char *limit,
 568                                              const unsigned int *hook_entries,
 569                                              const unsigned int *underflows,
 570                                              unsigned int valid_hooks)
 571 {
 572         unsigned int h;
 573         int err;
 574
 575         if ((unsigned long)e % __alignof__(struct arpt_entry) != 0 ||
 576             (unsigned char *)e + sizeof(struct arpt_entry) >= limit ||
 577             (unsigned char *)e + e->next_offset > limit) {
 578                 duprintf("Bad offset %p\n", e);
 579                 return -EINVAL;
 580         }
 581
 582         if (e->next_offset
 583             < sizeof(struct arpt_entry) + sizeof(struct xt_entry_target)) {
 584                 duprintf("checking: element %p size %u\n",
 585                          e, e->next_offset);
 586                 return -EINVAL;
 587         }
 588
 589         err = check_entry(e);
 590         if (err)
 591                 return err;
 592
 593         /* Check hooks & underflows */
 594         for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
 595                 if (!(valid_hooks & (1 << h)))
 596                         continue;
 597                 if ((unsigned char *)e - base == hook_entries[h])
 598                         newinfo->hook_entry[h] = hook_entries[h];
 599                 if ((unsigned char *)e - base == underflows[h]) {
 600                         if (!check_underflow(e)) {
 601                                 pr_debug("Underflows must be unconditional and "
 602                                          "use the STANDARD target with "
 603                                          "ACCEPT/DROP\n");
 604                                 return -EINVAL;
 605                         }
 606                         newinfo->underflow[h] = underflows[h];
 607                 }
 608         }
 609
 610         /* Clear counters and comefrom */
 611         e->counters = ((struct xt_counters) { 0, 0 });
 612         e->comefrom = 0;
 613         return 0;
 614 }
 615
 616 static inline void cleanup_entry(struct arpt_entry *e)
 617 {
 618         struct xt_tgdtor_param par;
 619         struct xt_entry_target *t;
 620
 621         t = arpt_get_target(e);
 622         par.target   = t->u.kernel.target;
 623         par.targinfo = t->data;
 624         par.family   = NFPROTO_ARP;
 625         if (par.target->destroy != NULL)
 626                 par.target->destroy(&par);
 627         module_put(par.target->me);
 628         xt_percpu_counter_free(e->counters.pcnt);
 629 }
 630
 631 /* Checks and translates the user-supplied table segment (held in
 632  * newinfo).
 633  */
 634 static int translate_table(struct xt_table_info *newinfo, void *entry0,
 635                            const struct arpt_replace *repl)
 636 {
 637         struct arpt_entry *iter;
 638         unsigned int i;
 639         int ret = 0;
 640
 641         newinfo->size = repl->size;
 642         newinfo->number = repl->num_entries;
 643
 644         /* Init all hooks to impossible value. */
 645         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
 646                 newinfo->hook_entry[i] = 0xFFFFFFFF;
 647                 newinfo->underflow[i] = 0xFFFFFFFF;
 648         }
 649
 650         duprintf("translate_table: size %u\n", newinfo->size);
 651         i = 0;
 652
 653         /* Walk through entries, checking offsets. */
 654         xt_entry_foreach(iter, entry0, newinfo->size) {
 655                 ret = check_entry_size_and_hooks(iter, newinfo, entry0,
 656                                                  entry0 + repl->size,
 657                                                  repl->hook_entry,
 658                                                  repl->underflow,
 659                                                  repl->valid_hooks);
 660                 if (ret != 0)
 661                         break;
 662                 ++i;
 663                 if (strcmp(arpt_get_target(iter)->u.user.name,
 664                     XT_ERROR_TARGET) == 0)
 665                         ++newinfo->stacksize;
 666         }
 667         duprintf("translate_table: ARPT_ENTRY_ITERATE gives %d\n", ret);
 668         if (ret != 0)
 669                 return ret;
 670
 671         if (i != repl->num_entries) {
 672                 duprintf("translate_table: %u not %u entries\n",
 673                          i, repl->num_entries);
 674                 return -EINVAL;
 675         }
 676
 677         /* Check hooks all assigned */
 678         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
 679                 /* Only hooks which are valid */
 680                 if (!(repl->valid_hooks & (1 << i)))
 681                         continue;
 682                 if (newinfo->hook_entry[i] == 0xFFFFFFFF) {
 683                         duprintf("Invalid hook entry %u %u\n",
 684                                  i, repl->hook_entry[i]);
 685                         return -EINVAL;
 686                 }
 687                 if (newinfo->underflow[i] == 0xFFFFFFFF) {
 688                         duprintf("Invalid underflow %u %u\n",
 689                                  i, repl->underflow[i]);
 690                         return -EINVAL;
 691                 }
 692         }
 693
 694         if (!mark_source_chains(newinfo, repl->valid_hooks, entry0)) {
 695                 duprintf("Looping hook\n");
 696                 return -ELOOP;
 697         }
 698
 699         /* Finally, each sanity check must pass */
 700         i = 0;
 701         xt_entry_foreach(iter, entry0, newinfo->size) {
 702                 ret = find_check_entry(iter, repl->name, repl->size);
 703                 if (ret != 0)
 704                         break;
 705                 ++i;
 706         }
 707
 708         if (ret != 0) {
 709                 xt_entry_foreach(iter, entry0, newinfo->size) {
 710                         if (i-- == 0)
 711                                 break;
 712                         cleanup_entry(iter);
 713                 }
 714                 return ret;
 715         }
 716
 717         return ret;
 718 }
 719
 720 static void get_counters(const struct xt_table_info *t,
 721                          struct xt_counters counters[])
 722 {
 723         struct arpt_entry *iter;
 724         unsigned int cpu;
 725         unsigned int i;
 726
 727         for_each_possible_cpu(cpu) {
 728                 seqcount_t *s = &per_cpu(xt_recseq, cpu);
 729
 730                 i = 0;
 731                 xt_entry_foreach(iter, t->entries, t->size) {
 732                         struct xt_counters *tmp;
 733                         u64 bcnt, pcnt;
 734                         unsigned int start;
 735
 736                         tmp = xt_get_per_cpu_counter(&iter->counters, cpu);
 737                         do {
 738                                 start = read_seqcount_begin(s);
 739                                 bcnt = tmp->bcnt;
 740                                 pcnt = tmp->pcnt;
 741                         } while (read_seqcount_retry(s, start));
 742
 743                         ADD_COUNTER(counters[i], bcnt, pcnt);
 744                         ++i;
 745                 }
 746         }
 747 }
 748
 749 static struct xt_counters *alloc_counters(const struct xt_table *table)
 750 {
 751         unsigned int countersize;
 752         struct xt_counters *counters;
 753         const struct xt_table_info *private = table->private;
 754
 755         /* We need atomic snapshot of counters: rest doesn't change
 756          * (other than comefrom, which userspace doesn't care
 757          * about).
 758          */
 759         countersize = sizeof(struct xt_counters) * private->number;
 760         counters = vzalloc(countersize);
 761
 762         if (counters == NULL)
 763                 return ERR_PTR(-ENOMEM);
 764
 765         get_counters(private, counters);
 766
 767         return counters;
 768 }
 769
 770 static int copy_entries_to_user(unsigned int total_size,
 771                                 const struct xt_table *table,
 772                                 void __user *userptr)
 773 {
 774         unsigned int off, num;
 775         const struct arpt_entry *e;
 776         struct xt_counters *counters;
 777         struct xt_table_info *private = table->private;
 778         int ret = 0;
 779         void *loc_cpu_entry;
 780
 781         counters = alloc_counters(table);
 782         if (IS_ERR(counters))
 783                 return PTR_ERR(counters);
 784
 785         loc_cpu_entry = private->entries;
 786         /* ... then copy entire thing ... */
 787         if (copy_to_user(userptr, loc_cpu_entry, total_size) != 0) {
 788                 ret = -EFAULT;
 789                 goto free_counters;
 790         }
 791
 792         /* FIXME: use iterator macros --RR */
 793         /* ... then go back and fix counters and names */
 794         for (off = 0, num = 0; off < total_size; off += e->next_offset, num++){
 795                 const struct xt_entry_target *t;
 796
 797                 e = (struct arpt_entry *)(loc_cpu_entry + off);
 798                 if (copy_to_user(userptr + off
 799                                  + offsetof(struct arpt_entry, counters),
 800                                  &counters[num],
 801                                  sizeof(counters[num])) != 0) {
 802                         ret = -EFAULT;
 803                         goto free_counters;
 804                 }
 805
 806                 t = arpt_get_target_c(e);
 807                 if (copy_to_user(userptr + off + e->target_offset
 808                                  + offsetof(struct xt_entry_target,
 809                                             u.user.name),
 810                                  t->u.kernel.target->name,
 811                                  strlen(t->u.kernel.target->name)+1) != 0) {
 812                         ret = -EFAULT;
 813                         goto free_counters;
 814                 }
 815         }
 816
 817  free_counters:
 818         vfree(counters);
 819         return ret;
 820 }
 821
 822 #ifdef CONFIG_COMPAT
 823 static void compat_standard_from_user(void *dst, const void *src)
 824 {
 825         int v = *(compat_int_t *)src;
 826
 827         if (v > 0)
 828                 v += xt_compat_calc_jump(NFPROTO_ARP, v);
 829         memcpy(dst, &v, sizeof(v));
 830 }
 831
 832 static int compat_standard_to_user(void __user *dst, const void *src)
 833 {
 834         compat_int_t cv = *(int *)src;
 835
 836         if (cv > 0)
 837                 cv -= xt_compat_calc_jump(NFPROTO_ARP, cv);
 838         return copy_to_user(dst, &cv, sizeof(cv)) ? -EFAULT : 0;
 839 }
 840
 841 static int compat_calc_entry(const struct arpt_entry *e,
 842                              const struct xt_table_info *info,
 843                              const void *base, struct xt_table_info *newinfo)
 844 {
 845         const struct xt_entry_target *t;
 846         unsigned int entry_offset;
 847         int off, i, ret;
 848
 849         off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
 850         entry_offset = (void *)e - base;
 851
 852         t = arpt_get_target_c(e);
 853         off += xt_compat_target_offset(t->u.kernel.target);
 854         newinfo->size -= off;
 855         ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
 856         if (ret)
 857                 return ret;
 858
 859         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
 860                 if (info->hook_entry[i] &&
 861                     (e < (struct arpt_entry *)(base + info->hook_entry[i])))
 862                         newinfo->hook_entry[i] -= off;
 863                 if (info->underflow[i] &&
 864                     (e < (struct arpt_entry *)(base + info->underflow[i])))
 865                         newinfo->underflow[i] -= off;
 866         }
 867         return 0;
 868 }
 869
 870 static int compat_table_info(const struct xt_table_info *info,
 871                              struct xt_table_info *newinfo)
 872 {
 873         struct arpt_entry *iter;
 874         const void *loc_cpu_entry;
 875         int ret;
 876
 877         if (!newinfo || !info)
 878                 return -EINVAL;
 879
 880         /* we dont care about newinfo->entries */
 881         memcpy(newinfo, info, offsetof(struct xt_table_info, entries));
 882         newinfo->initial_entries = 0;
 883         loc_cpu_entry = info->entries;
 884         xt_compat_init_offsets(NFPROTO_ARP, info->number);
 885         xt_entry_foreach(iter, loc_cpu_entry, info->size) {
 886                 ret = compat_calc_entry(iter, info, loc_cpu_entry, newinfo);
 887                 if (ret != 0)
 888                         return ret;
 889         }
 890         return 0;
 891 }
 892 #endif
 893
 894 static int get_info(struct net *net, void __user *user,
 895                     const int *len, int compat)
 896 {
 897         char name[XT_TABLE_MAXNAMELEN];
 898         struct xt_table *t;
 899         int ret;
 900
 901         if (*len != sizeof(struct arpt_getinfo)) {
 902                 duprintf("length %u != %Zu\n", *len,
 903                          sizeof(struct arpt_getinfo));
 904                 return -EINVAL;
 905         }
 906
 907         if (copy_from_user(name, user, sizeof(name)) != 0)
 908                 return -EFAULT;
 909
 910         name[XT_TABLE_MAXNAMELEN-1] = '\0';
 911 #ifdef CONFIG_COMPAT
 912         if (compat)
 913                 xt_compat_lock(NFPROTO_ARP);
 914 #endif
 915         t = try_then_request_module(xt_find_table_lock(net, NFPROTO_ARP, name),
 916                                     "arptable_%s", name);
 917         if (!IS_ERR_OR_NULL(t)) {
 918                 struct arpt_getinfo info;
 919                 const struct xt_table_info *private = t->private;
 920 #ifdef CONFIG_COMPAT
 921                 struct xt_table_info tmp;
 922
 923                 if (compat) {
 924                         ret = compat_table_info(private, &tmp);
 925                         xt_compat_flush_offsets(NFPROTO_ARP);
 926                         private = &tmp;
 927                 }
 928 #endif
 929                 memset(&info, 0, sizeof(info));
 930                 info.valid_hooks = t->valid_hooks;
 931                 memcpy(info.hook_entry, private->hook_entry,
 932                        sizeof(info.hook_entry));
 933                 memcpy(info.underflow, private->underflow,
 934                        sizeof(info.underflow));
 935                 info.num_entries = private->number;
 936                 info.size = private->size;
 937                 strcpy(info.name, name);
 938
 939                 if (copy_to_user(user, &info, *len) != 0)
 940                         ret = -EFAULT;
 941                 else
 942                         ret = 0;
 943                 xt_table_unlock(t);
 944                 module_put(t->me);
 945         } else
 946                 ret = t ? PTR_ERR(t) : -ENOENT;
 947 #ifdef CONFIG_COMPAT
 948         if (compat)
 949                 xt_compat_unlock(NFPROTO_ARP);
 950 #endif
 951         return ret;
 952 }
 953
 954 static int get_entries(struct net *net, struct arpt_get_entries __user *uptr,
 955                        const int *len)
 956 {
 957         int ret;
 958         struct arpt_get_entries get;
 959         struct xt_table *t;
 960
 961         if (*len < sizeof(get)) {
 962                 duprintf("get_entries: %u < %Zu\n", *len, sizeof(get));
 963                 return -EINVAL;
 964         }
 965         if (copy_from_user(&get, uptr, sizeof(get)) != 0)
 966                 return -EFAULT;
 967         if (*len != sizeof(struct arpt_get_entries) + get.size) {
 968                 duprintf("get_entries: %u != %Zu\n", *len,
 969                          sizeof(struct arpt_get_entries) + get.size);
 970                 return -EINVAL;
 971         }
 972         get.name[sizeof(get.name) - 1] = '\0';
 973
 974         t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
 975         if (!IS_ERR_OR_NULL(t)) {
 976                 const struct xt_table_info *private = t->private;
 977
 978                 duprintf("t->private->number = %u\n",
 979                          private->number);
 980                 if (get.size == private->size)
 981                         ret = copy_entries_to_user(private->size,
 982                                                    t, uptr->entrytable);
 983                 else {
 984                         duprintf("get_entries: I've got %u not %u!\n",
 985                                  private->size, get.size);
 986                         ret = -EAGAIN;
 987                 }
 988                 module_put(t->me);
 989                 xt_table_unlock(t);
 990         } else
 991                 ret = t ? PTR_ERR(t) : -ENOENT;
 992
 993         return ret;
 994 }
 995
 996 static int __do_replace(struct net *net, const char *name,
 997                         unsigned int valid_hooks,
 998                         struct xt_table_info *newinfo,
 999                         unsigned int num_counters,
1000                         void __user *counters_ptr)
1001 {
1002         int ret;
1003         struct xt_table *t;
1004         struct xt_table_info *oldinfo;
1005         struct xt_counters *counters;
1006         void *loc_cpu_old_entry;
1007         struct arpt_entry *iter;
1008
1009         ret = 0;
1010         counters = vzalloc(num_counters * sizeof(struct xt_counters));
1011         if (!counters) {
1012                 ret = -ENOMEM;
1013                 goto out;
1014         }
1015
1016         t = try_then_request_module(xt_find_table_lock(net, NFPROTO_ARP, name),
1017                                     "arptable_%s", name);
1018         if (IS_ERR_OR_NULL(t)) {
1019                 ret = t ? PTR_ERR(t) : -ENOENT;
1020                 goto free_newinfo_counters_untrans;
1021         }
1022
1023         /* You lied! */
1024         if (valid_hooks != t->valid_hooks) {
1025                 duprintf("Valid hook crap: %08X vs %08X\n",
1026                          valid_hooks, t->valid_hooks);
1027                 ret = -EINVAL;
1028                 goto put_module;
1029         }
1030
1031         oldinfo = xt_replace_table(t, num_counters, newinfo, &ret);
1032         if (!oldinfo)
1033                 goto put_module;
1034
1035         /* Update module usage count based on number of rules */
1036         duprintf("do_replace: oldnum=%u, initnum=%u, newnum=%u\n",
1037                 oldinfo->number, oldinfo->initial_entries, newinfo->number);
1038         if ((oldinfo->number > oldinfo->initial_entries) ||
1039             (newinfo->number <= oldinfo->initial_entries))
1040                 module_put(t->me);
1041         if ((oldinfo->number > oldinfo->initial_entries) &&
1042             (newinfo->number <= oldinfo->initial_entries))
1043                 module_put(t->me);
1044
1045         /* Get the old counters, and synchronize with replace */
1046         get_counters(oldinfo, counters);
1047
1048         /* Decrease module usage counts and free resource */
1049         loc_cpu_old_entry = oldinfo->entries;
1050         xt_entry_foreach(iter, loc_cpu_old_entry, oldinfo->size)
1051                 cleanup_entry(iter);
1052
1053         xt_free_table_info(oldinfo);
1054         if (copy_to_user(counters_ptr, counters,
1055                          sizeof(struct xt_counters) * num_counters) != 0) {
1056                 /* Silent error, can't fail, new table is already in place */
1057                 net_warn_ratelimited("arptables: counters copy to user failed while replacing table\n");
1058         }
1059         vfree(counters);
1060         xt_table_unlock(t);
1061         return ret;
1062
1063  put_module:
1064         module_put(t->me);
1065         xt_table_unlock(t);
1066  free_newinfo_counters_untrans:
1067         vfree(counters);
1068  out:
1069         return ret;
1070 }
1071
1072 static int do_replace(struct net *net, const void __user *user,
1073                       unsigned int len)
1074 {
1075         int ret;
1076         struct arpt_replace tmp;
1077         struct xt_table_info *newinfo;
1078         void *loc_cpu_entry;
1079         struct arpt_entry *iter;
1080
1081         if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
1082                 return -EFAULT;
1083
1084         /* overflow check */
1085         if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
1086                 return -ENOMEM;
1087         if (tmp.num_counters == 0)
1088                 return -EINVAL;
1089
1090         tmp.name[sizeof(tmp.name)-1] = 0;
1091
1092         newinfo = xt_alloc_table_info(tmp.size);
1093         if (!newinfo)
1094                 return -ENOMEM;
1095
1096         loc_cpu_entry = newinfo->entries;
1097         if (copy_from_user(loc_cpu_entry, user + sizeof(tmp),
1098                            tmp.size) != 0) {
1099                 ret = -EFAULT;
1100                 goto free_newinfo;
1101         }
1102
1103         ret = translate_table(newinfo, loc_cpu_entry, &tmp);
1104         if (ret != 0)
1105                 goto free_newinfo;
1106
1107         duprintf("arp_tables: Translated table\n");
1108
1109         ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
1110                            tmp.num_counters, tmp.counters);
1111         if (ret)
1112                 goto free_newinfo_untrans;
1113         return 0;
1114
1115  free_newinfo_untrans:
1116         xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
1117                 cleanup_entry(iter);
1118  free_newinfo:
1119         xt_free_table_info(newinfo);
1120         return ret;
1121 }
1122
1123 static int do_add_counters(struct net *net, const void __user *user,
1124                            unsigned int len, int compat)
1125 {
1126         unsigned int i;
1127         struct xt_counters_info tmp;
1128         struct xt_counters *paddc;
1129         unsigned int num_counters;
1130         const char *name;
1131         int size;
1132         void *ptmp;
1133         struct xt_table *t;
1134         const struct xt_table_info *private;
1135         int ret = 0;
1136         struct arpt_entry *iter;
1137         unsigned int addend;
1138 #ifdef CONFIG_COMPAT
1139         struct compat_xt_counters_info compat_tmp;
1140
1141         if (compat) {
1142                 ptmp = &compat_tmp;
1143                 size = sizeof(struct compat_xt_counters_info);
1144         } else
1145 #endif
1146         {
1147                 ptmp = &tmp;
1148                 size = sizeof(struct xt_counters_info);
1149         }
1150
1151         if (copy_from_user(ptmp, user, size) != 0)
1152                 return -EFAULT;
1153
1154 #ifdef CONFIG_COMPAT
1155         if (compat) {
1156                 num_counters = compat_tmp.num_counters;
1157                 name = compat_tmp.name;
1158         } else
1159 #endif
1160         {
1161                 num_counters = tmp.num_counters;
1162                 name = tmp.name;
1163         }
1164
1165         if (len != size + num_counters * sizeof(struct xt_counters))
1166                 return -EINVAL;
1167
1168         paddc = vmalloc(len - size);
1169         if (!paddc)
1170                 return -ENOMEM;
1171
1172         if (copy_from_user(paddc, user + size, len - size) != 0) {
1173                 ret = -EFAULT;
1174                 goto free;
1175         }
1176
1177         t = xt_find_table_lock(net, NFPROTO_ARP, name);
1178         if (IS_ERR_OR_NULL(t)) {
1179                 ret = t ? PTR_ERR(t) : -ENOENT;
1180                 goto free;
1181         }
1182
1183         local_bh_disable();
1184         private = t->private;
1185         if (private->number != num_counters) {
1186                 ret = -EINVAL;
1187                 goto unlock_up_free;
1188         }
1189
1190         i = 0;
1191
1192         addend = xt_write_recseq_begin();
1193         xt_entry_foreach(iter,  private->entries, private->size) {
1194                 struct xt_counters *tmp;
1195
1196                 tmp = xt_get_this_cpu_counter(&iter->counters);
1197                 ADD_COUNTER(*tmp, paddc[i].bcnt, paddc[i].pcnt);
1198                 ++i;
1199         }
1200         xt_write_recseq_end(addend);
1201  unlock_up_free:
1202         local_bh_enable();
1203         xt_table_unlock(t);
1204         module_put(t->me);
1205  free:
1206         vfree(paddc);
1207
1208         return ret;
1209 }
1210
1211 #ifdef CONFIG_COMPAT
1212 static inline void compat_release_entry(struct compat_arpt_entry *e)
1213 {
1214         struct xt_entry_target *t;
1215
1216         t = compat_arpt_get_target(e);
1217         module_put(t->u.kernel.target->me);
1218 }
1219
1220 static inline int
1221 check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
1222                                   struct xt_table_info *newinfo,
1223                                   unsigned int *size,
1224                                   const unsigned char *base,
1225                                   const unsigned char *limit,
1226                                   const unsigned int *hook_entries,
1227                                   const unsigned int *underflows,
1228                                   const char *name)
1229 {
1230         struct xt_entry_target *t;
1231         struct xt_target *target;
1232         unsigned int entry_offset;
1233         int ret, off, h;
1234
1235         duprintf("check_compat_entry_size_and_hooks %p\n", e);
1236         if ((unsigned long)e % __alignof__(struct compat_arpt_entry) != 0 ||
1237             (unsigned char *)e + sizeof(struct compat_arpt_entry) >= limit ||
1238             (unsigned char *)e + e->next_offset > limit) {
1239                 duprintf("Bad offset %p, limit = %p\n", e, limit);
1240                 return -EINVAL;
1241         }
1242
1243         if (e->next_offset < sizeof(struct compat_arpt_entry) +
1244                              sizeof(struct compat_xt_entry_target)) {
1245                 duprintf("checking: element %p size %u\n",
1246                          e, e->next_offset);
1247                 return -EINVAL;
1248         }
1249
1250         /* For purposes of check_entry casting the compat entry is fine */
1251         ret = check_entry((struct arpt_entry *)e);
1252         if (ret)
1253                 return ret;
1254
1255         off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1256         entry_offset = (void *)e - (void *)base;
1257
1258         t = compat_arpt_get_target(e);
1259         target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
1260                                         t->u.user.revision);
1261         if (IS_ERR(target)) {
1262                 duprintf("check_compat_entry_size_and_hooks: `%s' not found\n",
1263                          t->u.user.name);
1264                 ret = PTR_ERR(target);
1265                 goto out;
1266         }
1267         t->u.kernel.target = target;
1268
1269         off += xt_compat_target_offset(target);
1270         *size += off;
1271         ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
1272         if (ret)
1273                 goto release_target;
1274
1275         /* Check hooks & underflows */
1276         for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
1277                 if ((unsigned char *)e - base == hook_entries[h])
1278                         newinfo->hook_entry[h] = hook_entries[h];
1279                 if ((unsigned char *)e - base == underflows[h])
1280                         newinfo->underflow[h] = underflows[h];
1281         }
1282
1283         /* Clear counters and comefrom */
1284         memset(&e->counters, 0, sizeof(e->counters));
1285         e->comefrom = 0;
1286         return 0;
1287
1288 release_target:
1289         module_put(t->u.kernel.target->me);
1290 out:
1291         return ret;
1292 }
1293
1294 static int
1295 compat_copy_entry_from_user(struct compat_arpt_entry *e, void **dstptr,
1296                             unsigned int *size, const char *name,
1297                             struct xt_table_info *newinfo, unsigned char *base)
1298 {
1299         struct xt_entry_target *t;
1300         struct xt_target *target;
1301         struct arpt_entry *de;
1302         unsigned int origsize;
1303         int ret, h;
1304
1305         ret = 0;
1306         origsize = *size;
1307         de = (struct arpt_entry *)*dstptr;
1308         memcpy(de, e, sizeof(struct arpt_entry));
1309         memcpy(&de->counters, &e->counters, sizeof(e->counters));
1310
1311         *dstptr += sizeof(struct arpt_entry);
1312         *size += sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1313
1314         de->target_offset = e->target_offset - (origsize - *size);
1315         t = compat_arpt_get_target(e);
1316         target = t->u.kernel.target;
1317         xt_compat_target_from_user(t, dstptr, size);
1318
1319         de->next_offset = e->next_offset - (origsize - *size);
1320         for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
1321                 if ((unsigned char *)de - base < newinfo->hook_entry[h])
1322                         newinfo->hook_entry[h] -= origsize - *size;
1323                 if ((unsigned char *)de - base < newinfo->underflow[h])
1324                         newinfo->underflow[h] -= origsize - *size;
1325         }
1326         return ret;
1327 }
1328
1329 static int translate_compat_table(const char *name,
1330                                   unsigned int valid_hooks,
1331                                   struct xt_table_info **pinfo,
1332                                   void **pentry0,
1333                                   unsigned int total_size,
1334                                   unsigned int number,
1335                                   unsigned int *hook_entries,
1336                                   unsigned int *underflows)
1337 {
1338         unsigned int i, j;
1339         struct xt_table_info *newinfo, *info;
1340         void *pos, *entry0, *entry1;
1341         struct compat_arpt_entry *iter0;
1342         struct arpt_entry *iter1;
1343         unsigned int size;
1344         int ret = 0;
1345
1346         info = *pinfo;
1347         entry0 = *pentry0;
1348         size = total_size;
1349         info->number = number;
1350
1351         /* Init all hooks to impossible value. */
1352         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1353                 info->hook_entry[i] = 0xFFFFFFFF;
1354                 info->underflow[i] = 0xFFFFFFFF;
1355         }
1356
1357         duprintf("translate_compat_table: size %u\n", info->size);
1358         j = 0;
1359         xt_compat_lock(NFPROTO_ARP);
1360         xt_compat_init_offsets(NFPROTO_ARP, number);
1361         /* Walk through entries, checking offsets. */
1362         xt_entry_foreach(iter0, entry0, total_size) {
1363                 ret = check_compat_entry_size_and_hooks(iter0, info, &size,
1364                                                         entry0,
1365                                                         entry0 + total_size,
1366                                                         hook_entries,
1367                                                         underflows,
1368                                                         name);
1369                 if (ret != 0)
1370                         goto out_unlock;
1371                 ++j;
1372         }
1373
1374         ret = -EINVAL;
1375         if (j != number) {
1376                 duprintf("translate_compat_table: %u not %u entries\n",
1377                          j, number);
1378                 goto out_unlock;
1379         }
1380
1381         /* Check hooks all assigned */
1382         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1383                 /* Only hooks which are valid */
1384                 if (!(valid_hooks & (1 << i)))
1385                         continue;
1386                 if (info->hook_entry[i] == 0xFFFFFFFF) {
1387                         duprintf("Invalid hook entry %u %u\n",
1388                                  i, hook_entries[i]);
1389                         goto out_unlock;
1390                 }
1391                 if (info->underflow[i] == 0xFFFFFFFF) {
1392                         duprintf("Invalid underflow %u %u\n",
1393                                  i, underflows[i]);
1394                         goto out_unlock;
1395                 }
1396         }
1397
1398         ret = -ENOMEM;
1399         newinfo = xt_alloc_table_info(size);
1400         if (!newinfo)
1401                 goto out_unlock;
1402
1403         newinfo->number = number;
1404         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1405                 newinfo->hook_entry[i] = info->hook_entry[i];
1406                 newinfo->underflow[i] = info->underflow[i];
1407         }
1408         entry1 = newinfo->entries;
1409         pos = entry1;
1410         size = total_size;
1411         xt_entry_foreach(iter0, entry0, total_size) {
1412                 ret = compat_copy_entry_from_user(iter0, &pos, &size,
1413                                                   name, newinfo, entry1);
1414                 if (ret != 0)
1415                         break;
1416         }
1417         xt_compat_flush_offsets(NFPROTO_ARP);
1418         xt_compat_unlock(NFPROTO_ARP);
1419         if (ret)
1420                 goto free_newinfo;
1421
1422         ret = -ELOOP;
1423         if (!mark_source_chains(newinfo, valid_hooks, entry1))
1424                 goto free_newinfo;
1425
1426         i = 0;
1427         xt_entry_foreach(iter1, entry1, newinfo->size) {
1428                 iter1->counters.pcnt = xt_percpu_counter_alloc();
1429                 if (IS_ERR_VALUE(iter1->counters.pcnt)) {
1430                         ret = -ENOMEM;
1431                         break;
1432                 }
1433
1434                 ret = check_target(iter1, name);
1435                 if (ret != 0) {
1436                         xt_percpu_counter_free(iter1->counters.pcnt);
1437                         break;
1438                 }
1439                 ++i;
1440                 if (strcmp(arpt_get_target(iter1)->u.user.name,
1441                     XT_ERROR_TARGET) == 0)
1442                         ++newinfo->stacksize;
1443         }
1444         if (ret) {
1445                 /*
1446                  * The first i matches need cleanup_entry (calls ->destroy)
1447                  * because they had called ->check already. The other j-i
1448                  * entries need only release.
1449                  */
1450                 int skip = i;
1451                 j -= i;
1452                 xt_entry_foreach(iter0, entry0, newinfo->size) {
1453                         if (skip-- > 0)
1454                                 continue;
1455                         if (j-- == 0)
1456                                 break;
1457                         compat_release_entry(iter0);
1458                 }
1459                 xt_entry_foreach(iter1, entry1, newinfo->size) {
1460                         if (i-- == 0)
1461                                 break;
1462                         cleanup_entry(iter1);
1463                 }
1464                 xt_free_table_info(newinfo);
1465                 return ret;
1466         }
1467
1468         *pinfo = newinfo;
1469         *pentry0 = entry1;
1470         xt_free_table_info(info);
1471         return 0;
1472
1473 free_newinfo:
1474         xt_free_table_info(newinfo);
1475 out:
1476         xt_entry_foreach(iter0, entry0, total_size) {
1477                 if (j-- == 0)
1478                         break;
1479                 compat_release_entry(iter0);
1480         }
1481         return ret;
1482 out_unlock:
1483         xt_compat_flush_offsets(NFPROTO_ARP);
1484         xt_compat_unlock(NFPROTO_ARP);
1485         goto out;
1486 }
1487
1488 struct compat_arpt_replace {
1489         char                            name[XT_TABLE_MAXNAMELEN];
1490         u32                             valid_hooks;
1491         u32                             num_entries;
1492         u32                             size;
1493         u32                             hook_entry[NF_ARP_NUMHOOKS];
1494         u32                             underflow[NF_ARP_NUMHOOKS];
1495         u32                             num_counters;
1496         compat_uptr_t                   counters;
1497         struct compat_arpt_entry        entries[0];
1498 };
1499
1500 static int compat_do_replace(struct net *net, void __user *user,
1501                              unsigned int len)
1502 {
1503         int ret;
1504         struct compat_arpt_replace tmp;
1505         struct xt_table_info *newinfo;
1506         void *loc_cpu_entry;
1507         struct arpt_entry *iter;
1508
1509         if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
1510                 return -EFAULT;
1511
1512         /* overflow check */
1513         if (tmp.size >= INT_MAX / num_possible_cpus())
1514                 return -ENOMEM;
1515         if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
1516                 return -ENOMEM;
1517         if (tmp.num_counters == 0)
1518                 return -EINVAL;
1519
1520         tmp.name[sizeof(tmp.name)-1] = 0;
1521
1522         newinfo = xt_alloc_table_info(tmp.size);
1523         if (!newinfo)
1524                 return -ENOMEM;
1525
1526         loc_cpu_entry = newinfo->entries;
1527         if (copy_from_user(loc_cpu_entry, user + sizeof(tmp), tmp.size) != 0) {
1528                 ret = -EFAULT;
1529                 goto free_newinfo;
1530         }
1531
1532         ret = translate_compat_table(tmp.name, tmp.valid_hooks,
1533                                      &newinfo, &loc_cpu_entry, tmp.size,
1534                                      tmp.num_entries, tmp.hook_entry,
1535                                      tmp.underflow);
1536         if (ret != 0)
1537                 goto free_newinfo;
1538
1539         duprintf("compat_do_replace: Translated table\n");
1540
1541         ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
1542                            tmp.num_counters, compat_ptr(tmp.counters));
1543         if (ret)
1544                 goto free_newinfo_untrans;
1545         return 0;
1546
1547  free_newinfo_untrans:
1548         xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
1549                 cleanup_entry(iter);
1550  free_newinfo:
1551         xt_free_table_info(newinfo);
1552         return ret;
1553 }
1554
1555 static int compat_do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user,
1556                                   unsigned int len)
1557 {
1558         int ret;
1559
1560         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1561                 return -EPERM;
1562
1563         switch (cmd) {
1564         case ARPT_SO_SET_REPLACE:
1565                 ret = compat_do_replace(sock_net(sk), user, len);
1566                 break;
1567
1568         case ARPT_SO_SET_ADD_COUNTERS:
1569                 ret = do_add_counters(sock_net(sk), user, len, 1);
1570                 break;
1571
1572         default:
1573                 duprintf("do_arpt_set_ctl:  unknown request %i\n", cmd);
1574                 ret = -EINVAL;
1575         }
1576
1577         return ret;
1578 }
1579
1580 static int compat_copy_entry_to_user(struct arpt_entry *e, void __user **dstptr,
1581                                      compat_uint_t *size,
1582                                      struct xt_counters *counters,
1583                                      unsigned int i)
1584 {
1585         struct xt_entry_target *t;
1586         struct compat_arpt_entry __user *ce;
1587         u_int16_t target_offset, next_offset;
1588         compat_uint_t origsize;
1589         int ret;
1590
1591         origsize = *size;
1592         ce = (struct compat_arpt_entry __user *)*dstptr;
1593         if (copy_to_user(ce, e, sizeof(struct arpt_entry)) != 0 ||
1594             copy_to_user(&ce->counters, &counters[i],
1595             sizeof(counters[i])) != 0)
1596                 return -EFAULT;
1597
1598         *dstptr += sizeof(struct compat_arpt_entry);
1599         *size -= sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1600
1601         target_offset = e->target_offset - (origsize - *size);
1602
1603         t = arpt_get_target(e);
1604         ret = xt_compat_target_to_user(t, dstptr, size);
1605         if (ret)
1606                 return ret;
1607         next_offset = e->next_offset - (origsize - *size);
1608         if (put_user(target_offset, &ce->target_offset) != 0 ||
1609             put_user(next_offset, &ce->next_offset) != 0)
1610                 return -EFAULT;
1611         return 0;
1612 }
1613
1614 static int compat_copy_entries_to_user(unsigned int total_size,
1615                                        struct xt_table *table,
1616                                        void __user *userptr)
1617 {
1618         struct xt_counters *counters;
1619         const struct xt_table_info *private = table->private;
1620         void __user *pos;
1621         unsigned int size;
1622         int ret = 0;
1623         unsigned int i = 0;
1624         struct arpt_entry *iter;
1625
1626         counters = alloc_counters(table);
1627         if (IS_ERR(counters))
1628                 return PTR_ERR(counters);
1629
1630         pos = userptr;
1631         size = total_size;
1632         xt_entry_foreach(iter, private->entries, total_size) {
1633                 ret = compat_copy_entry_to_user(iter, &pos,
1634                                                 &size, counters, i++);
1635                 if (ret != 0)
1636                         break;
1637         }
1638         vfree(counters);
1639         return ret;
1640 }
1641
1642 struct compat_arpt_get_entries {
1643         char name[XT_TABLE_MAXNAMELEN];
1644         compat_uint_t size;
1645         struct compat_arpt_entry entrytable[0];
1646 };
1647
1648 static int compat_get_entries(struct net *net,
1649                               struct compat_arpt_get_entries __user *uptr,
1650                               int *len)
1651 {
1652         int ret;
1653         struct compat_arpt_get_entries get;
1654         struct xt_table *t;
1655
1656         if (*len < sizeof(get)) {
1657                 duprintf("compat_get_entries: %u < %zu\n", *len, sizeof(get));
1658                 return -EINVAL;
1659         }
1660         if (copy_from_user(&get, uptr, sizeof(get)) != 0)
1661                 return -EFAULT;
1662         if (*len != sizeof(struct compat_arpt_get_entries) + get.size) {
1663                 duprintf("compat_get_entries: %u != %zu\n",
1664                          *len, sizeof(get) + get.size);
1665                 return -EINVAL;
1666         }
1667         get.name[sizeof(get.name) - 1] = '\0';
1668
1669         xt_compat_lock(NFPROTO_ARP);
1670         t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
1671         if (!IS_ERR_OR_NULL(t)) {
1672                 const struct xt_table_info *private = t->private;
1673                 struct xt_table_info info;
1674
1675                 duprintf("t->private->number = %u\n", private->number);
1676                 ret = compat_table_info(private, &info);
1677                 if (!ret && get.size == info.size) {
1678                         ret = compat_copy_entries_to_user(private->size,
1679                                                           t, uptr->entrytable);
1680                 } else if (!ret) {
1681                         duprintf("compat_get_entries: I've got %u not %u!\n",
1682                                  private->size, get.size);
1683                         ret = -EAGAIN;
1684                 }
1685                 xt_compat_flush_offsets(NFPROTO_ARP);
1686                 module_put(t->me);
1687                 xt_table_unlock(t);
1688         } else
1689                 ret = t ? PTR_ERR(t) : -ENOENT;
1690
1691         xt_compat_unlock(NFPROTO_ARP);
1692         return ret;
1693 }
1694
1695 static int do_arpt_get_ctl(struct sock *, int, void __user *, int *);
1696
1697 static int compat_do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user,
1698                                   int *len)
1699 {
1700         int ret;
1701
1702         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1703                 return -EPERM;
1704
1705         switch (cmd) {
1706         case ARPT_SO_GET_INFO:
1707                 ret = get_info(sock_net(sk), user, len, 1);
1708                 break;
1709         case ARPT_SO_GET_ENTRIES:
1710                 ret = compat_get_entries(sock_net(sk), user, len);
1711                 break;
1712         default:
1713                 ret = do_arpt_get_ctl(sk, cmd, user, len);
1714         }
1715         return ret;
1716 }
1717 #endif
1718
1719 static int do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
1720 {
1721         int ret;
1722
1723         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1724                 return -EPERM;
1725
1726         switch (cmd) {
1727         case ARPT_SO_SET_REPLACE:
1728                 ret = do_replace(sock_net(sk), user, len);
1729                 break;
1730
1731         case ARPT_SO_SET_ADD_COUNTERS:
1732                 ret = do_add_counters(sock_net(sk), user, len, 0);
1733                 break;
1734
1735         default:
1736                 duprintf("do_arpt_set_ctl:  unknown request %i\n", cmd);
1737                 ret = -EINVAL;
1738         }
1739
1740         return ret;
1741 }
1742
1743 static int do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
1744 {
1745         int ret;
1746
1747         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1748                 return -EPERM;
1749
1750         switch (cmd) {
1751         case ARPT_SO_GET_INFO:
1752                 ret = get_info(sock_net(sk), user, len, 0);
1753                 break;
1754
1755         case ARPT_SO_GET_ENTRIES:
1756                 ret = get_entries(sock_net(sk), user, len);
1757                 break;
1758
1759         case ARPT_SO_GET_REVISION_TARGET: {
1760                 struct xt_get_revision rev;
1761
1762                 if (*len != sizeof(rev)) {
1763                         ret = -EINVAL;
1764                         break;
1765                 }
1766                 if (copy_from_user(&rev, user, sizeof(rev)) != 0) {
1767                         ret = -EFAULT;
1768                         break;
1769                 }
1770                 rev.name[sizeof(rev.name)-1] = 0;
1771
1772                 try_then_request_module(xt_find_revision(NFPROTO_ARP, rev.name,
1773                                                          rev.revision, 1, &ret),
1774                                         "arpt_%s", rev.name);
1775                 break;
1776         }
1777
1778         default:
1779                 duprintf("do_arpt_get_ctl: unknown request %i\n", cmd);
1780                 ret = -EINVAL;
1781         }
1782
1783         return ret;
1784 }
1785
1786 static void __arpt_unregister_table(struct xt_table *table)
1787 {
1788         struct xt_table_info *private;
1789         void *loc_cpu_entry;
1790         struct module *table_owner = table->me;
1791         struct arpt_entry *iter;
1792
1793         private = xt_unregister_table(table);
1794
1795         /* Decrease module usage counts and free resources */
1796         loc_cpu_entry = private->entries;
1797         xt_entry_foreach(iter, loc_cpu_entry, private->size)
1798                 cleanup_entry(iter);
1799         if (private->number > private->initial_entries)
1800                 module_put(table_owner);
1801         xt_free_table_info(private);
1802 }
1803
1804 int arpt_register_table(struct net *net,
1805                         const struct xt_table *table,
1806                         const struct arpt_replace *repl,
1807                         const struct nf_hook_ops *ops,
1808                         struct xt_table **res)
1809 {
1810         int ret;
1811         struct xt_table_info *newinfo;
1812         struct xt_table_info bootstrap = {0};
1813         void *loc_cpu_entry;
1814         struct xt_table *new_table;
1815
1816         newinfo = xt_alloc_table_info(repl->size);
1817         if (!newinfo)
1818                 return -ENOMEM;
1819
1820         loc_cpu_entry = newinfo->entries;
1821         memcpy(loc_cpu_entry, repl->entries, repl->size);
1822
1823         ret = translate_table(newinfo, loc_cpu_entry, repl);
1824         duprintf("arpt_register_table: translate table gives %d\n", ret);
1825         if (ret != 0)
1826                 goto out_free;
1827
1828         new_table = xt_register_table(net, table, &bootstrap, newinfo);
1829         if (IS_ERR(new_table)) {
1830                 ret = PTR_ERR(new_table);
1831                 goto out_free;
1832         }
1833
1834         /* set res now, will see skbs right after nf_register_net_hooks */
1835         WRITE_ONCE(*res, new_table);
1836
1837         ret = nf_register_net_hooks(net, ops, hweight32(table->valid_hooks));
1838         if (ret != 0) {
1839                 __arpt_unregister_table(new_table);
1840                 *res = NULL;
1841         }
1842
1843         return ret;
1844
1845 out_free:
1846         xt_free_table_info(newinfo);
1847         return ret;
1848 }
1849
1850 void arpt_unregister_table(struct net *net, struct xt_table *table,
1851                            const struct nf_hook_ops *ops)
1852 {
1853         nf_unregister_net_hooks(net, ops, hweight32(table->valid_hooks));
1854         __arpt_unregister_table(table);
1855 }
1856
1857 /* The built-in targets: standard (NULL) and error. */
1858 static struct xt_target arpt_builtin_tg[] __read_mostly = {
1859         {
1860                 .name             = XT_STANDARD_TARGET,
1861                 .targetsize       = sizeof(int),
1862                 .family           = NFPROTO_ARP,
1863 #ifdef CONFIG_COMPAT
1864                 .compatsize       = sizeof(compat_int_t),
1865                 .compat_from_user = compat_standard_from_user,
1866                 .compat_to_user   = compat_standard_to_user,
1867 #endif
1868         },
1869         {
1870                 .name             = XT_ERROR_TARGET,
1871                 .target           = arpt_error,
1872                 .targetsize       = XT_FUNCTION_MAXNAMELEN,
1873                 .family           = NFPROTO_ARP,
1874         },
1875 };
1876
1877 static struct nf_sockopt_ops arpt_sockopts = {
1878         .pf             = PF_INET,
1879         .set_optmin     = ARPT_BASE_CTL,
1880         .set_optmax     = ARPT_SO_SET_MAX+1,
1881         .set            = do_arpt_set_ctl,
1882 #ifdef CONFIG_COMPAT
1883         .compat_set     = compat_do_arpt_set_ctl,
1884 #endif
1885         .get_optmin     = ARPT_BASE_CTL,
1886         .get_optmax     = ARPT_SO_GET_MAX+1,
1887         .get            = do_arpt_get_ctl,
1888 #ifdef CONFIG_COMPAT
1889         .compat_get     = compat_do_arpt_get_ctl,
1890 #endif
1891         .owner          = THIS_MODULE,
1892 };
1893
1894 static int __net_init arp_tables_net_init(struct net *net)
1895 {
1896         return xt_proto_init(net, NFPROTO_ARP);
1897 }
1898
1899 static void __net_exit arp_tables_net_exit(struct net *net)
1900 {
1901         xt_proto_fini(net, NFPROTO_ARP);
1902 }
1903
1904 static struct pernet_operations arp_tables_net_ops = {
1905         .init = arp_tables_net_init,
1906         .exit = arp_tables_net_exit,
1907 };
1908
1909 static int __init arp_tables_init(void)
1910 {
1911         int ret;
1912
1913         ret = register_pernet_subsys(&arp_tables_net_ops);
1914         if (ret < 0)
1915                 goto err1;
1916
1917         /* No one else will be downing sem now, so we won't sleep */
1918         ret = xt_register_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1919         if (ret < 0)
1920                 goto err2;
1921
1922         /* Register setsockopt */
1923         ret = nf_register_sockopt(&arpt_sockopts);
1924         if (ret < 0)
1925                 goto err4;
1926
1927         pr_info("arp_tables: (C) 2002 David S. Miller\n");
1928         return 0;
1929
1930 err4:
1931         xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1932 err2:
1933         unregister_pernet_subsys(&arp_tables_net_ops);
1934 err1:
1935         return ret;
1936 }
1937
1938 static void __exit arp_tables_fini(void)
1939 {
1940         nf_unregister_sockopt(&arpt_sockopts);
1941         xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1942         unregister_pernet_subsys(&arp_tables_net_ops);
1943 }
1944
1945 EXPORT_SYMBOL(arpt_register_table);
1946 EXPORT_SYMBOL(arpt_unregister_table);
1947 EXPORT_SYMBOL(arpt_do_table);
1948
1949 module_init(arp_tables_init);
1950 module_exit(arp_tables_fini);