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...)  printk(format , ## args)
  42 #else
  43 #define dprintf(format, args...)
  44 #endif
  45
  46 #ifdef DEBUG_ARP_TABLES_USER
  47 #define duprintf(format, args...) printk(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                                 if (unlikely(stackidx >= private->stacksize)) {
 333                                         verdict = NF_DROP;
 334                                         break;
 335                                 }
 336                                 jumpstack[stackidx++] = e;
 337                         }
 338
 339                         e = get_entry(table_base, v);
 340                         continue;
 341                 }
 342
 343                 acpar.target   = t->u.kernel.target;
 344                 acpar.targinfo = t->data;
 345                 verdict = t->u.kernel.target->target(skb, &acpar);
 346
 347                 /* Target might have changed stuff. */
 348                 arp = arp_hdr(skb);
 349
 350                 if (verdict == XT_CONTINUE)
 351                         e = arpt_next_entry(e);
 352                 else
 353                         /* Verdict */
 354                         break;
 355         } while (!acpar.hotdrop);
 356         xt_write_recseq_end(addend);
 357         local_bh_enable();
 358
 359         if (acpar.hotdrop)
 360                 return NF_DROP;
 361         else
 362                 return verdict;
 363 }
 364
 365 /* All zeroes == unconditional rule. */
 366 static inline bool unconditional(const struct arpt_entry *e)
 367 {
 368         static const struct arpt_arp uncond;
 369
 370         return e->target_offset == sizeof(struct arpt_entry) &&
 371                memcmp(&e->arp, &uncond, sizeof(uncond)) == 0;
 372 }
 373
 374 /* Figures out from what hook each rule can be called: returns 0 if
 375  * there are loops.  Puts hook bitmask in comefrom.
 376  */
 377 static int mark_source_chains(const struct xt_table_info *newinfo,
 378                               unsigned int valid_hooks, void *entry0,
 379                               unsigned int *offsets)
 380 {
 381         unsigned int hook;
 382
 383         /* No recursion; use packet counter to save back ptrs (reset
 384          * to 0 as we leave), and comefrom to save source hook bitmask.
 385          */
 386         for (hook = 0; hook < NF_ARP_NUMHOOKS; hook++) {
 387                 unsigned int pos = newinfo->hook_entry[hook];
 388                 struct arpt_entry *e
 389                         = (struct arpt_entry *)(entry0 + pos);
 390
 391                 if (!(valid_hooks & (1 << hook)))
 392                         continue;
 393
 394                 /* Set initial back pointer. */
 395                 e->counters.pcnt = pos;
 396
 397                 for (;;) {
 398                         const struct xt_standard_target *t
 399                                 = (void *)arpt_get_target_c(e);
 400                         int visited = e->comefrom & (1 << hook);
 401
 402                         if (e->comefrom & (1 << NF_ARP_NUMHOOKS)) {
 403                                 pr_notice("arptables: loop hook %u pos %u %08X.\n",
 404                                        hook, pos, e->comefrom);
 405                                 return 0;
 406                         }
 407                         e->comefrom
 408                                 |= ((1 << hook) | (1 << NF_ARP_NUMHOOKS));
 409
 410                         /* Unconditional return/END. */
 411                         if ((unconditional(e) &&
 412                              (strcmp(t->target.u.user.name,
 413                                      XT_STANDARD_TARGET) == 0) &&
 414                              t->verdict < 0) || visited) {
 415                                 unsigned int oldpos, size;
 416
 417                                 if ((strcmp(t->target.u.user.name,
 418                                             XT_STANDARD_TARGET) == 0) &&
 419                                     t->verdict < -NF_MAX_VERDICT - 1) {
 420                                         duprintf("mark_source_chains: bad "
 421                                                 "negative verdict (%i)\n",
 422                                                                 t->verdict);
 423                                         return 0;
 424                                 }
 425
 426                                 /* Return: backtrack through the last
 427                                  * big jump.
 428                                  */
 429                                 do {
 430                                         e->comefrom ^= (1<<NF_ARP_NUMHOOKS);
 431                                         oldpos = pos;
 432                                         pos = e->counters.pcnt;
 433                                         e->counters.pcnt = 0;
 434
 435                                         /* We're at the start. */
 436                                         if (pos == oldpos)
 437                                                 goto next;
 438
 439                                         e = (struct arpt_entry *)
 440                                                 (entry0 + pos);
 441                                 } while (oldpos == pos + e->next_offset);
 442
 443                                 /* Move along one */
 444                                 size = e->next_offset;
 445                                 e = (struct arpt_entry *)
 446                                         (entry0 + pos + size);
 447                                 if (pos + size >= newinfo->size)
 448                                         return 0;
 449                                 e->counters.pcnt = pos;
 450                                 pos += size;
 451                         } else {
 452                                 int newpos = t->verdict;
 453
 454                                 if (strcmp(t->target.u.user.name,
 455                                            XT_STANDARD_TARGET) == 0 &&
 456                                     newpos >= 0) {
 457                                         if (newpos > newinfo->size -
 458                                                 sizeof(struct arpt_entry)) {
 459                                                 duprintf("mark_source_chains: "
 460                                                         "bad verdict (%i)\n",
 461                                                                 newpos);
 462                                                 return 0;
 463                                         }
 464
 465                                         /* This a jump; chase it. */
 466                                         duprintf("Jump rule %u -> %u\n",
 467                                                  pos, newpos);
 468                                         if (!xt_find_jump_offset(offsets, newpos,
 469                                                                  newinfo->number))
 470                                                 return 0;
 471                                         e = (struct arpt_entry *)
 472                                                 (entry0 + newpos);
 473                                 } else {
 474                                         /* ... this is a fallthru */
 475                                         newpos = pos + e->next_offset;
 476                                         if (newpos >= newinfo->size)
 477                                                 return 0;
 478                                 }
 479                                 e = (struct arpt_entry *)
 480                                         (entry0 + newpos);
 481                                 e->counters.pcnt = pos;
 482                                 pos = newpos;
 483                         }
 484                 }
 485 next:
 486                 duprintf("Finished chain %u\n", hook);
 487         }
 488         return 1;
 489 }
 490
 491 static int check_target(struct arpt_entry *e, struct net *net, const char *name)
 492 {
 493         struct xt_entry_target *t = arpt_get_target(e);
 494         int ret;
 495         struct xt_tgchk_param par = {
 496                 .net       = net,
 497                 .table     = name,
 498                 .entryinfo = e,
 499                 .target    = t->u.kernel.target,
 500                 .targinfo  = t->data,
 501                 .hook_mask = e->comefrom,
 502                 .family    = NFPROTO_ARP,
 503         };
 504
 505         ret = xt_check_target(&par, t->u.target_size - sizeof(*t), 0, false);
 506         if (ret < 0) {
 507                 duprintf("arp_tables: check failed for `%s'.\n",
 508                          t->u.kernel.target->name);
 509                 return ret;
 510         }
 511         return 0;
 512 }
 513
 514 static int
 515 find_check_entry(struct arpt_entry *e, struct net *net, const char *name,
 516                  unsigned int size,
 517                  struct xt_percpu_counter_alloc_state *alloc_state)
 518 {
 519         struct xt_entry_target *t;
 520         struct xt_target *target;
 521         int ret;
 522
 523         if (!xt_percpu_counter_alloc(alloc_state, &e->counters))
 524                 return -ENOMEM;
 525
 526         t = arpt_get_target(e);
 527         target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
 528                                         t->u.user.revision);
 529         if (IS_ERR(target)) {
 530                 duprintf("find_check_entry: `%s' not found\n", t->u.user.name);
 531                 ret = PTR_ERR(target);
 532                 goto out;
 533         }
 534         t->u.kernel.target = target;
 535
 536         ret = check_target(e, net, name);
 537         if (ret)
 538                 goto err;
 539         return 0;
 540 err:
 541         module_put(t->u.kernel.target->me);
 542 out:
 543         xt_percpu_counter_free(&e->counters);
 544
 545         return ret;
 546 }
 547
 548 static bool check_underflow(const struct arpt_entry *e)
 549 {
 550         const struct xt_entry_target *t;
 551         unsigned int verdict;
 552
 553         if (!unconditional(e))
 554                 return false;
 555         t = arpt_get_target_c(e);
 556         if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
 557                 return false;
 558         verdict = ((struct xt_standard_target *)t)->verdict;
 559         verdict = -verdict - 1;
 560         return verdict == NF_DROP || verdict == NF_ACCEPT;
 561 }
 562
 563 static inline int check_entry_size_and_hooks(struct arpt_entry *e,
 564                                              struct xt_table_info *newinfo,
 565                                              const unsigned char *base,
 566                                              const unsigned char *limit,
 567                                              const unsigned int *hook_entries,
 568                                              const unsigned int *underflows,
 569                                              unsigned int valid_hooks)
 570 {
 571         unsigned int h;
 572         int err;
 573
 574         if ((unsigned long)e % __alignof__(struct arpt_entry) != 0 ||
 575             (unsigned char *)e + sizeof(struct arpt_entry) >= limit ||
 576             (unsigned char *)e + e->next_offset > limit) {
 577                 duprintf("Bad offset %p\n", e);
 578                 return -EINVAL;
 579         }
 580
 581         if (e->next_offset
 582             < sizeof(struct arpt_entry) + sizeof(struct xt_entry_target)) {
 583                 duprintf("checking: element %p size %u\n",
 584                          e, e->next_offset);
 585                 return -EINVAL;
 586         }
 587
 588         if (!arp_checkentry(&e->arp))
 589                 return -EINVAL;
 590
 591         err = xt_check_entry_offsets(e, e->elems, e->target_offset,
 592                                      e->next_offset);
 593         if (err)
 594                 return err;
 595
 596         /* Check hooks & underflows */
 597         for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
 598                 if (!(valid_hooks & (1 << h)))
 599                         continue;
 600                 if ((unsigned char *)e - base == hook_entries[h])
 601                         newinfo->hook_entry[h] = hook_entries[h];
 602                 if ((unsigned char *)e - base == underflows[h]) {
 603                         if (!check_underflow(e)) {
 604                                 pr_debug("Underflows must be unconditional and "
 605                                          "use the STANDARD target with "
 606                                          "ACCEPT/DROP\n");
 607                                 return -EINVAL;
 608                         }
 609                         newinfo->underflow[h] = underflows[h];
 610                 }
 611         }
 612
 613         /* Clear counters and comefrom */
 614         e->counters = ((struct xt_counters) { 0, 0 });
 615         e->comefrom = 0;
 616         return 0;
 617 }
 618
 619 static inline void cleanup_entry(struct arpt_entry *e)
 620 {
 621         struct xt_tgdtor_param par;
 622         struct xt_entry_target *t;
 623
 624         t = arpt_get_target(e);
 625         par.target   = t->u.kernel.target;
 626         par.targinfo = t->data;
 627         par.family   = NFPROTO_ARP;
 628         if (par.target->destroy != NULL)
 629                 par.target->destroy(&par);
 630         module_put(par.target->me);
 631         xt_percpu_counter_free(&e->counters);
 632 }
 633
 634 /* Checks and translates the user-supplied table segment (held in
 635  * newinfo).
 636  */
 637 static int translate_table(struct net *net,
 638                            struct xt_table_info *newinfo,
 639                            void *entry0,
 640                            const struct arpt_replace *repl)
 641 {
 642         struct xt_percpu_counter_alloc_state alloc_state = { 0 };
 643         struct arpt_entry *iter;
 644         unsigned int *offsets;
 645         unsigned int i;
 646         int ret = 0;
 647
 648         newinfo->size = repl->size;
 649         newinfo->number = repl->num_entries;
 650
 651         /* Init all hooks to impossible value. */
 652         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
 653                 newinfo->hook_entry[i] = 0xFFFFFFFF;
 654                 newinfo->underflow[i] = 0xFFFFFFFF;
 655         }
 656
 657         duprintf("translate_table: size %u\n", newinfo->size);
 658         offsets = xt_alloc_entry_offsets(newinfo->number);
 659         if (!offsets)
 660                 return -ENOMEM;
 661         i = 0;
 662
 663         /* Walk through entries, checking offsets. */
 664         xt_entry_foreach(iter, entry0, newinfo->size) {
 665                 ret = check_entry_size_and_hooks(iter, newinfo, entry0,
 666                                                  entry0 + repl->size,
 667                                                  repl->hook_entry,
 668                                                  repl->underflow,
 669                                                  repl->valid_hooks);
 670                 if (ret != 0)
 671                         goto out_free;
 672                 if (i < repl->num_entries)
 673                         offsets[i] = (void *)iter - entry0;
 674                 ++i;
 675                 if (strcmp(arpt_get_target(iter)->u.user.name,
 676                     XT_ERROR_TARGET) == 0)
 677                         ++newinfo->stacksize;
 678         }
 679         duprintf("translate_table: ARPT_ENTRY_ITERATE gives %d\n", ret);
 680         if (ret != 0)
 681                 goto out_free;
 682
 683         ret = -EINVAL;
 684         if (i != repl->num_entries) {
 685                 duprintf("translate_table: %u not %u entries\n",
 686                          i, repl->num_entries);
 687                 goto out_free;
 688         }
 689
 690         /* Check hooks all assigned */
 691         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
 692                 /* Only hooks which are valid */
 693                 if (!(repl->valid_hooks & (1 << i)))
 694                         continue;
 695                 if (newinfo->hook_entry[i] == 0xFFFFFFFF) {
 696                         duprintf("Invalid hook entry %u %u\n",
 697                                  i, repl->hook_entry[i]);
 698                         goto out_free;
 699                 }
 700                 if (newinfo->underflow[i] == 0xFFFFFFFF) {
 701                         duprintf("Invalid underflow %u %u\n",
 702                                  i, repl->underflow[i]);
 703                         goto out_free;
 704                 }
 705         }
 706
 707         if (!mark_source_chains(newinfo, repl->valid_hooks, entry0, offsets)) {
 708                 ret = -ELOOP;
 709                 goto out_free;
 710         }
 711         kvfree(offsets);
 712
 713         /* Finally, each sanity check must pass */
 714         i = 0;
 715         xt_entry_foreach(iter, entry0, newinfo->size) {
 716                 ret = find_check_entry(iter, net, repl->name, repl->size,
 717                                        &alloc_state);
 718                 if (ret != 0)
 719                         break;
 720                 ++i;
 721         }
 722
 723         if (ret != 0) {
 724                 xt_entry_foreach(iter, entry0, newinfo->size) {
 725                         if (i-- == 0)
 726                                 break;
 727                         cleanup_entry(iter);
 728                 }
 729                 return ret;
 730         }
 731
 732         return ret;
 733  out_free:
 734         kvfree(offsets);
 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(net, 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         struct xt_table *t;
1148         const struct xt_table_info *private;
1149         int ret = 0;
1150         struct arpt_entry *iter;
1151         unsigned int addend;
1152
1153         paddc = xt_copy_counters_from_user(user, len, &tmp, compat);
1154         if (IS_ERR(paddc))
1155                 return PTR_ERR(paddc);
1156
1157         t = xt_find_table_lock(net, NFPROTO_ARP, tmp.name);
1158         if (IS_ERR_OR_NULL(t)) {
1159                 ret = t ? PTR_ERR(t) : -ENOENT;
1160                 goto free;
1161         }
1162
1163         local_bh_disable();
1164         private = t->private;
1165         if (private->number != tmp.num_counters) {
1166                 ret = -EINVAL;
1167                 goto unlock_up_free;
1168         }
1169
1170         i = 0;
1171
1172         addend = xt_write_recseq_begin();
1173         xt_entry_foreach(iter,  private->entries, private->size) {
1174                 struct xt_counters *tmp;
1175
1176                 tmp = xt_get_this_cpu_counter(&iter->counters);
1177                 ADD_COUNTER(*tmp, paddc[i].bcnt, paddc[i].pcnt);
1178                 ++i;
1179         }
1180         xt_write_recseq_end(addend);
1181  unlock_up_free:
1182         local_bh_enable();
1183         xt_table_unlock(t);
1184         module_put(t->me);
1185  free:
1186         vfree(paddc);
1187
1188         return ret;
1189 }
1190
1191 #ifdef CONFIG_COMPAT
1192 struct compat_arpt_replace {
1193         char                            name[XT_TABLE_MAXNAMELEN];
1194         u32                             valid_hooks;
1195         u32                             num_entries;
1196         u32                             size;
1197         u32                             hook_entry[NF_ARP_NUMHOOKS];
1198         u32                             underflow[NF_ARP_NUMHOOKS];
1199         u32                             num_counters;
1200         compat_uptr_t                   counters;
1201         struct compat_arpt_entry        entries[0];
1202 };
1203
1204 static inline void compat_release_entry(struct compat_arpt_entry *e)
1205 {
1206         struct xt_entry_target *t;
1207
1208         t = compat_arpt_get_target(e);
1209         module_put(t->u.kernel.target->me);
1210 }
1211
1212 static int
1213 check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
1214                                   struct xt_table_info *newinfo,
1215                                   unsigned int *size,
1216                                   const unsigned char *base,
1217                                   const unsigned char *limit)
1218 {
1219         struct xt_entry_target *t;
1220         struct xt_target *target;
1221         unsigned int entry_offset;
1222         int ret, off;
1223
1224         duprintf("check_compat_entry_size_and_hooks %p\n", e);
1225         if ((unsigned long)e % __alignof__(struct compat_arpt_entry) != 0 ||
1226             (unsigned char *)e + sizeof(struct compat_arpt_entry) >= limit ||
1227             (unsigned char *)e + e->next_offset > limit) {
1228                 duprintf("Bad offset %p, limit = %p\n", e, limit);
1229                 return -EINVAL;
1230         }
1231
1232         if (e->next_offset < sizeof(struct compat_arpt_entry) +
1233                              sizeof(struct compat_xt_entry_target)) {
1234                 duprintf("checking: element %p size %u\n",
1235                          e, e->next_offset);
1236                 return -EINVAL;
1237         }
1238
1239         if (!arp_checkentry(&e->arp))
1240                 return -EINVAL;
1241
1242         ret = xt_compat_check_entry_offsets(e, e->elems, e->target_offset,
1243                                             e->next_offset);
1244         if (ret)
1245                 return ret;
1246
1247         off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1248         entry_offset = (void *)e - (void *)base;
1249
1250         t = compat_arpt_get_target(e);
1251         target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
1252                                         t->u.user.revision);
1253         if (IS_ERR(target)) {
1254                 duprintf("check_compat_entry_size_and_hooks: `%s' not found\n",
1255                          t->u.user.name);
1256                 ret = PTR_ERR(target);
1257                 goto out;
1258         }
1259         t->u.kernel.target = target;
1260
1261         off += xt_compat_target_offset(target);
1262         *size += off;
1263         ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
1264         if (ret)
1265                 goto release_target;
1266
1267         return 0;
1268
1269 release_target:
1270         module_put(t->u.kernel.target->me);
1271 out:
1272         return ret;
1273 }
1274
1275 static void
1276 compat_copy_entry_from_user(struct compat_arpt_entry *e, void **dstptr,
1277                             unsigned int *size,
1278                             struct xt_table_info *newinfo, unsigned char *base)
1279 {
1280         struct xt_entry_target *t;
1281         struct xt_target *target;
1282         struct arpt_entry *de;
1283         unsigned int origsize;
1284         int h;
1285
1286         origsize = *size;
1287         de = (struct arpt_entry *)*dstptr;
1288         memcpy(de, e, sizeof(struct arpt_entry));
1289         memcpy(&de->counters, &e->counters, sizeof(e->counters));
1290
1291         *dstptr += sizeof(struct arpt_entry);
1292         *size += sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1293
1294         de->target_offset = e->target_offset - (origsize - *size);
1295         t = compat_arpt_get_target(e);
1296         target = t->u.kernel.target;
1297         xt_compat_target_from_user(t, dstptr, size);
1298
1299         de->next_offset = e->next_offset - (origsize - *size);
1300         for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
1301                 if ((unsigned char *)de - base < newinfo->hook_entry[h])
1302                         newinfo->hook_entry[h] -= origsize - *size;
1303                 if ((unsigned char *)de - base < newinfo->underflow[h])
1304                         newinfo->underflow[h] -= origsize - *size;
1305         }
1306 }
1307
1308 static int translate_compat_table(struct net *net,
1309                                   struct xt_table_info **pinfo,
1310                                   void **pentry0,
1311                                   const struct compat_arpt_replace *compatr)
1312 {
1313         unsigned int i, j;
1314         struct xt_table_info *newinfo, *info;
1315         void *pos, *entry0, *entry1;
1316         struct compat_arpt_entry *iter0;
1317         struct arpt_replace repl;
1318         unsigned int size;
1319         int ret = 0;
1320
1321         info = *pinfo;
1322         entry0 = *pentry0;
1323         size = compatr->size;
1324         info->number = compatr->num_entries;
1325
1326         duprintf("translate_compat_table: size %u\n", info->size);
1327         j = 0;
1328         xt_compat_lock(NFPROTO_ARP);
1329         xt_compat_init_offsets(NFPROTO_ARP, compatr->num_entries);
1330         /* Walk through entries, checking offsets. */
1331         xt_entry_foreach(iter0, entry0, compatr->size) {
1332                 ret = check_compat_entry_size_and_hooks(iter0, info, &size,
1333                                                         entry0,
1334                                                         entry0 + compatr->size);
1335                 if (ret != 0)
1336                         goto out_unlock;
1337                 ++j;
1338         }
1339
1340         ret = -EINVAL;
1341         if (j != compatr->num_entries) {
1342                 duprintf("translate_compat_table: %u not %u entries\n",
1343                          j, compatr->num_entries);
1344                 goto out_unlock;
1345         }
1346
1347         ret = -ENOMEM;
1348         newinfo = xt_alloc_table_info(size);
1349         if (!newinfo)
1350                 goto out_unlock;
1351
1352         memset(newinfo->entries, 0, size);
1353
1354         newinfo->number = compatr->num_entries;
1355         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1356                 newinfo->hook_entry[i] = compatr->hook_entry[i];
1357                 newinfo->underflow[i] = compatr->underflow[i];
1358         }
1359         entry1 = newinfo->entries;
1360         pos = entry1;
1361         size = compatr->size;
1362         xt_entry_foreach(iter0, entry0, compatr->size)
1363                 compat_copy_entry_from_user(iter0, &pos, &size,
1364                                             newinfo, entry1);
1365
1366         /* all module references in entry0 are now gone */
1367
1368         xt_compat_flush_offsets(NFPROTO_ARP);
1369         xt_compat_unlock(NFPROTO_ARP);
1370
1371         memcpy(&repl, compatr, sizeof(*compatr));
1372
1373         for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1374                 repl.hook_entry[i] = newinfo->hook_entry[i];
1375                 repl.underflow[i] = newinfo->underflow[i];
1376         }
1377
1378         repl.num_counters = 0;
1379         repl.counters = NULL;
1380         repl.size = newinfo->size;
1381         ret = translate_table(net, newinfo, entry1, &repl);
1382         if (ret)
1383                 goto free_newinfo;
1384
1385         *pinfo = newinfo;
1386         *pentry0 = entry1;
1387         xt_free_table_info(info);
1388         return 0;
1389
1390 free_newinfo:
1391         xt_free_table_info(newinfo);
1392         return ret;
1393 out_unlock:
1394         xt_compat_flush_offsets(NFPROTO_ARP);
1395         xt_compat_unlock(NFPROTO_ARP);
1396         xt_entry_foreach(iter0, entry0, compatr->size) {
1397                 if (j-- == 0)
1398                         break;
1399                 compat_release_entry(iter0);
1400         }
1401         return ret;
1402 }
1403
1404 static int compat_do_replace(struct net *net, void __user *user,
1405                              unsigned int len)
1406 {
1407         int ret;
1408         struct compat_arpt_replace tmp;
1409         struct xt_table_info *newinfo;
1410         void *loc_cpu_entry;
1411         struct arpt_entry *iter;
1412
1413         if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
1414                 return -EFAULT;
1415
1416         /* overflow check */
1417         if (tmp.size >= INT_MAX / num_possible_cpus())
1418                 return -ENOMEM;
1419         if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
1420                 return -ENOMEM;
1421         if (tmp.num_counters == 0)
1422                 return -EINVAL;
1423
1424         tmp.name[sizeof(tmp.name)-1] = 0;
1425
1426         newinfo = xt_alloc_table_info(tmp.size);
1427         if (!newinfo)
1428                 return -ENOMEM;
1429
1430         loc_cpu_entry = newinfo->entries;
1431         if (copy_from_user(loc_cpu_entry, user + sizeof(tmp), tmp.size) != 0) {
1432                 ret = -EFAULT;
1433                 goto free_newinfo;
1434         }
1435
1436         ret = translate_compat_table(net, &newinfo, &loc_cpu_entry, &tmp);
1437         if (ret != 0)
1438                 goto free_newinfo;
1439
1440         duprintf("compat_do_replace: Translated table\n");
1441
1442         ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
1443                            tmp.num_counters, compat_ptr(tmp.counters));
1444         if (ret)
1445                 goto free_newinfo_untrans;
1446         return 0;
1447
1448  free_newinfo_untrans:
1449         xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
1450                 cleanup_entry(iter);
1451  free_newinfo:
1452         xt_free_table_info(newinfo);
1453         return ret;
1454 }
1455
1456 static int compat_do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user,
1457                                   unsigned int len)
1458 {
1459         int ret;
1460
1461         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1462                 return -EPERM;
1463
1464         switch (cmd) {
1465         case ARPT_SO_SET_REPLACE:
1466                 ret = compat_do_replace(sock_net(sk), user, len);
1467                 break;
1468
1469         case ARPT_SO_SET_ADD_COUNTERS:
1470                 ret = do_add_counters(sock_net(sk), user, len, 1);
1471                 break;
1472
1473         default:
1474                 duprintf("do_arpt_set_ctl:  unknown request %i\n", cmd);
1475                 ret = -EINVAL;
1476         }
1477
1478         return ret;
1479 }
1480
1481 static int compat_copy_entry_to_user(struct arpt_entry *e, void __user **dstptr,
1482                                      compat_uint_t *size,
1483                                      struct xt_counters *counters,
1484                                      unsigned int i)
1485 {
1486         struct xt_entry_target *t;
1487         struct compat_arpt_entry __user *ce;
1488         u_int16_t target_offset, next_offset;
1489         compat_uint_t origsize;
1490         int ret;
1491
1492         origsize = *size;
1493         ce = (struct compat_arpt_entry __user *)*dstptr;
1494         if (copy_to_user(ce, e, sizeof(struct arpt_entry)) != 0 ||
1495             copy_to_user(&ce->counters, &counters[i],
1496             sizeof(counters[i])) != 0)
1497                 return -EFAULT;
1498
1499         *dstptr += sizeof(struct compat_arpt_entry);
1500         *size -= sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1501
1502         target_offset = e->target_offset - (origsize - *size);
1503
1504         t = arpt_get_target(e);
1505         ret = xt_compat_target_to_user(t, dstptr, size);
1506         if (ret)
1507                 return ret;
1508         next_offset = e->next_offset - (origsize - *size);
1509         if (put_user(target_offset, &ce->target_offset) != 0 ||
1510             put_user(next_offset, &ce->next_offset) != 0)
1511                 return -EFAULT;
1512         return 0;
1513 }
1514
1515 static int compat_copy_entries_to_user(unsigned int total_size,
1516                                        struct xt_table *table,
1517                                        void __user *userptr)
1518 {
1519         struct xt_counters *counters;
1520         const struct xt_table_info *private = table->private;
1521         void __user *pos;
1522         unsigned int size;
1523         int ret = 0;
1524         unsigned int i = 0;
1525         struct arpt_entry *iter;
1526
1527         counters = alloc_counters(table);
1528         if (IS_ERR(counters))
1529                 return PTR_ERR(counters);
1530
1531         pos = userptr;
1532         size = total_size;
1533         xt_entry_foreach(iter, private->entries, total_size) {
1534                 ret = compat_copy_entry_to_user(iter, &pos,
1535                                                 &size, counters, i++);
1536                 if (ret != 0)
1537                         break;
1538         }
1539         vfree(counters);
1540         return ret;
1541 }
1542
1543 struct compat_arpt_get_entries {
1544         char name[XT_TABLE_MAXNAMELEN];
1545         compat_uint_t size;
1546         struct compat_arpt_entry entrytable[0];
1547 };
1548
1549 static int compat_get_entries(struct net *net,
1550                               struct compat_arpt_get_entries __user *uptr,
1551                               int *len)
1552 {
1553         int ret;
1554         struct compat_arpt_get_entries get;
1555         struct xt_table *t;
1556
1557         if (*len < sizeof(get)) {
1558                 duprintf("compat_get_entries: %u < %zu\n", *len, sizeof(get));
1559                 return -EINVAL;
1560         }
1561         if (copy_from_user(&get, uptr, sizeof(get)) != 0)
1562                 return -EFAULT;
1563         if (*len != sizeof(struct compat_arpt_get_entries) + get.size) {
1564                 duprintf("compat_get_entries: %u != %zu\n",
1565                          *len, sizeof(get) + get.size);
1566                 return -EINVAL;
1567         }
1568         get.name[sizeof(get.name) - 1] = '\0';
1569
1570         xt_compat_lock(NFPROTO_ARP);
1571         t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
1572         if (!IS_ERR_OR_NULL(t)) {
1573                 const struct xt_table_info *private = t->private;
1574                 struct xt_table_info info;
1575
1576                 duprintf("t->private->number = %u\n", private->number);
1577                 ret = compat_table_info(private, &info);
1578                 if (!ret && get.size == info.size) {
1579                         ret = compat_copy_entries_to_user(private->size,
1580                                                           t, uptr->entrytable);
1581                 } else if (!ret) {
1582                         duprintf("compat_get_entries: I've got %u not %u!\n",
1583                                  private->size, get.size);
1584                         ret = -EAGAIN;
1585                 }
1586                 xt_compat_flush_offsets(NFPROTO_ARP);
1587                 module_put(t->me);
1588                 xt_table_unlock(t);
1589         } else
1590                 ret = t ? PTR_ERR(t) : -ENOENT;
1591
1592         xt_compat_unlock(NFPROTO_ARP);
1593         return ret;
1594 }
1595
1596 static int do_arpt_get_ctl(struct sock *, int, void __user *, int *);
1597
1598 static int compat_do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user,
1599                                   int *len)
1600 {
1601         int ret;
1602
1603         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1604                 return -EPERM;
1605
1606         switch (cmd) {
1607         case ARPT_SO_GET_INFO:
1608                 ret = get_info(sock_net(sk), user, len, 1);
1609                 break;
1610         case ARPT_SO_GET_ENTRIES:
1611                 ret = compat_get_entries(sock_net(sk), user, len);
1612                 break;
1613         default:
1614                 ret = do_arpt_get_ctl(sk, cmd, user, len);
1615         }
1616         return ret;
1617 }
1618 #endif
1619
1620 static int do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
1621 {
1622         int ret;
1623
1624         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1625                 return -EPERM;
1626
1627         switch (cmd) {
1628         case ARPT_SO_SET_REPLACE:
1629                 ret = do_replace(sock_net(sk), user, len);
1630                 break;
1631
1632         case ARPT_SO_SET_ADD_COUNTERS:
1633                 ret = do_add_counters(sock_net(sk), user, len, 0);
1634                 break;
1635
1636         default:
1637                 duprintf("do_arpt_set_ctl:  unknown request %i\n", cmd);
1638                 ret = -EINVAL;
1639         }
1640
1641         return ret;
1642 }
1643
1644 static int do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
1645 {
1646         int ret;
1647
1648         if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1649                 return -EPERM;
1650
1651         switch (cmd) {
1652         case ARPT_SO_GET_INFO:
1653                 ret = get_info(sock_net(sk), user, len, 0);
1654                 break;
1655
1656         case ARPT_SO_GET_ENTRIES:
1657                 ret = get_entries(sock_net(sk), user, len);
1658                 break;
1659
1660         case ARPT_SO_GET_REVISION_TARGET: {
1661                 struct xt_get_revision rev;
1662
1663                 if (*len != sizeof(rev)) {
1664                         ret = -EINVAL;
1665                         break;
1666                 }
1667                 if (copy_from_user(&rev, user, sizeof(rev)) != 0) {
1668                         ret = -EFAULT;
1669                         break;
1670                 }
1671                 rev.name[sizeof(rev.name)-1] = 0;
1672
1673                 try_then_request_module(xt_find_revision(NFPROTO_ARP, rev.name,
1674                                                          rev.revision, 1, &ret),
1675                                         "arpt_%s", rev.name);
1676                 break;
1677         }
1678
1679         default:
1680                 duprintf("do_arpt_get_ctl: unknown request %i\n", cmd);
1681                 ret = -EINVAL;
1682         }
1683
1684         return ret;
1685 }
1686
1687 struct xt_table *arpt_register_table(struct net *net,
1688                                      const struct xt_table *table,
1689                                      const struct arpt_replace *repl)
1690 {
1691         int ret;
1692         struct xt_table_info *newinfo;
1693         struct xt_table_info bootstrap = {0};
1694         void *loc_cpu_entry;
1695         struct xt_table *new_table;
1696
1697         newinfo = xt_alloc_table_info(repl->size);
1698         if (!newinfo) {
1699                 ret = -ENOMEM;
1700                 goto out;
1701         }
1702
1703         loc_cpu_entry = newinfo->entries;
1704         memcpy(loc_cpu_entry, repl->entries, repl->size);
1705
1706         ret = translate_table(net, newinfo, loc_cpu_entry, repl);
1707         duprintf("arpt_register_table: translate table gives %d\n", ret);
1708         if (ret != 0)
1709                 goto out_free;
1710
1711         new_table = xt_register_table(net, table, &bootstrap, newinfo);
1712         if (IS_ERR(new_table)) {
1713                 ret = PTR_ERR(new_table);
1714                 goto out_free;
1715         }
1716         return new_table;
1717
1718 out_free:
1719         xt_free_table_info(newinfo);
1720 out:
1721         return ERR_PTR(ret);
1722 }
1723
1724 void arpt_unregister_table(struct xt_table *table)
1725 {
1726         struct xt_table_info *private;
1727         void *loc_cpu_entry;
1728         struct module *table_owner = table->me;
1729         struct arpt_entry *iter;
1730
1731         private = xt_unregister_table(table);
1732
1733         /* Decrease module usage counts and free resources */
1734         loc_cpu_entry = private->entries;
1735         xt_entry_foreach(iter, loc_cpu_entry, private->size)
1736                 cleanup_entry(iter);
1737         if (private->number > private->initial_entries)
1738                 module_put(table_owner);
1739         xt_free_table_info(private);
1740 }
1741
1742 /* The built-in targets: standard (NULL) and error. */
1743 static struct xt_target arpt_builtin_tg[] __read_mostly = {
1744         {
1745                 .name             = XT_STANDARD_TARGET,
1746                 .targetsize       = sizeof(int),
1747                 .family           = NFPROTO_ARP,
1748 #ifdef CONFIG_COMPAT
1749                 .compatsize       = sizeof(compat_int_t),
1750                 .compat_from_user = compat_standard_from_user,
1751                 .compat_to_user   = compat_standard_to_user,
1752 #endif
1753         },
1754         {
1755                 .name             = XT_ERROR_TARGET,
1756                 .target           = arpt_error,
1757                 .targetsize       = XT_FUNCTION_MAXNAMELEN,
1758                 .family           = NFPROTO_ARP,
1759         },
1760 };
1761
1762 static struct nf_sockopt_ops arpt_sockopts = {
1763         .pf             = PF_INET,
1764         .set_optmin     = ARPT_BASE_CTL,
1765         .set_optmax     = ARPT_SO_SET_MAX+1,
1766         .set            = do_arpt_set_ctl,
1767 #ifdef CONFIG_COMPAT
1768         .compat_set     = compat_do_arpt_set_ctl,
1769 #endif
1770         .get_optmin     = ARPT_BASE_CTL,
1771         .get_optmax     = ARPT_SO_GET_MAX+1,
1772         .get            = do_arpt_get_ctl,
1773 #ifdef CONFIG_COMPAT
1774         .compat_get     = compat_do_arpt_get_ctl,
1775 #endif
1776         .owner          = THIS_MODULE,
1777 };
1778
1779 static int __net_init arp_tables_net_init(struct net *net)
1780 {
1781         return xt_proto_init(net, NFPROTO_ARP);
1782 }
1783
1784 static void __net_exit arp_tables_net_exit(struct net *net)
1785 {
1786         xt_proto_fini(net, NFPROTO_ARP);
1787 }
1788
1789 static struct pernet_operations arp_tables_net_ops = {
1790         .init = arp_tables_net_init,
1791         .exit = arp_tables_net_exit,
1792 };
1793
1794 static int __init arp_tables_init(void)
1795 {
1796         int ret;
1797
1798         ret = register_pernet_subsys(&arp_tables_net_ops);
1799         if (ret < 0)
1800                 goto err1;
1801
1802         /* No one else will be downing sem now, so we won't sleep */
1803         ret = xt_register_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1804         if (ret < 0)
1805                 goto err2;
1806
1807         /* Register setsockopt */
1808         ret = nf_register_sockopt(&arpt_sockopts);
1809         if (ret < 0)
1810                 goto err4;
1811
1812         printk(KERN_INFO "arp_tables: (C) 2002 David S. Miller\n");
1813         return 0;
1814
1815 err4:
1816         xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1817 err2:
1818         unregister_pernet_subsys(&arp_tables_net_ops);
1819 err1:
1820         return ret;
1821 }
1822
1823 static void __exit arp_tables_fini(void)
1824 {
1825         nf_unregister_sockopt(&arpt_sockopts);
1826         xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1827         unregister_pernet_subsys(&arp_tables_net_ops);
1828 }
1829
1830 EXPORT_SYMBOL(arpt_register_table);
1831 EXPORT_SYMBOL(arpt_unregister_table);
1832 EXPORT_SYMBOL(arpt_do_table);
1833
1834 module_init(arp_tables_init);
1835 module_exit(arp_tables_fini);