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