arp_tables.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Packet matching code for ARP packets.
   4 *
   5 * Based heavily, if not almost entirely, upon ip_tables.c framework.
   6 *
   7 * Some ARP specific bits are:
   8 *
   9 * Copyright (C) 2002 David S. Miller (davem@redhat.com)
  10 * Copyright (C) 2006-2009 Patrick McHardy <kaber@trash.net>
  11 *
  12 */
  13#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14#include <linux/kernel.h>
  15#include <linux/skbuff.h>
  16#include <linux/netdevice.h>
  17#include <linux/capability.h>
  18#include <linux/if_arp.h>
  19#include <linux/kmod.h>
  20#include <linux/vmalloc.h>
  21#include <linux/proc_fs.h>
  22#include <linux/module.h>
  23#include <linux/init.h>
  24#include <linux/mutex.h>
  25#include <linux/err.h>
  26#include <net/compat.h>
  27#include <net/sock.h>
  28#include <linux/uaccess.h>
  29
  30#include <linux/netfilter/x_tables.h>
  31#include <linux/netfilter_arp/arp_tables.h>
  32#include "../../netfilter/xt_repldata.h"
  33
  34MODULE_LICENSE("GPL");
  35MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
  36MODULE_DESCRIPTION("arptables core");
  37
  38void *arpt_alloc_initial_table(const struct xt_table *info)
  39{
  40	return xt_alloc_initial_table(arpt, ARPT);
  41}
  42EXPORT_SYMBOL_GPL(arpt_alloc_initial_table);
  43
  44static inline int arp_devaddr_compare(const struct arpt_devaddr_info *ap,
  45				      const char *hdr_addr, int len)
  46{
  47	int i, ret;
  48
  49	if (len > ARPT_DEV_ADDR_LEN_MAX)
  50		len = ARPT_DEV_ADDR_LEN_MAX;
  51
  52	ret = 0;
  53	for (i = 0; i < len; i++)
  54		ret |= (hdr_addr[i] ^ ap->addr[i]) & ap->mask[i];
  55
  56	return ret != 0;
  57}
  58
  59/*
  60 * Unfortunately, _b and _mask are not aligned to an int (or long int)
  61 * Some arches dont care, unrolling the loop is a win on them.
  62 * For other arches, we only have a 16bit alignement.
  63 */
  64static unsigned long ifname_compare(const char *_a, const char *_b, const char *_mask)
  65{
  66#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
  67	unsigned long ret = ifname_compare_aligned(_a, _b, _mask);
  68#else
  69	unsigned long ret = 0;
  70	const u16 *a = (const u16 *)_a;
  71	const u16 *b = (const u16 *)_b;
  72	const u16 *mask = (const u16 *)_mask;
  73	int i;
  74
  75	for (i = 0; i < IFNAMSIZ/sizeof(u16); i++)
  76		ret |= (a[i] ^ b[i]) & mask[i];
  77#endif
  78	return ret;
  79}
  80
  81/* Returns whether packet matches rule or not. */
  82static inline int arp_packet_match(const struct arphdr *arphdr,
  83				   struct net_device *dev,
  84				   const char *indev,
  85				   const char *outdev,
  86				   const struct arpt_arp *arpinfo)
  87{
  88	const char *arpptr = (char *)(arphdr + 1);
  89	const char *src_devaddr, *tgt_devaddr;
  90	__be32 src_ipaddr, tgt_ipaddr;
  91	long ret;
  92
  93	if (NF_INVF(arpinfo, ARPT_INV_ARPOP,
  94		    (arphdr->ar_op & arpinfo->arpop_mask) != arpinfo->arpop))
  95		return 0;
  96
  97	if (NF_INVF(arpinfo, ARPT_INV_ARPHRD,
  98		    (arphdr->ar_hrd & arpinfo->arhrd_mask) != arpinfo->arhrd))
  99		return 0;
 100
 101	if (NF_INVF(arpinfo, ARPT_INV_ARPPRO,
 102		    (arphdr->ar_pro & arpinfo->arpro_mask) != arpinfo->arpro))
 103		return 0;
 104
 105	if (NF_INVF(arpinfo, ARPT_INV_ARPHLN,
 106		    (arphdr->ar_hln & arpinfo->arhln_mask) != arpinfo->arhln))
 107		return 0;
 108
 109	src_devaddr = arpptr;
 110	arpptr += dev->addr_len;
 111	memcpy(&src_ipaddr, arpptr, sizeof(u32));
 112	arpptr += sizeof(u32);
 113	tgt_devaddr = arpptr;
 114	arpptr += dev->addr_len;
 115	memcpy(&tgt_ipaddr, arpptr, sizeof(u32));
 116
 117	if (NF_INVF(arpinfo, ARPT_INV_SRCDEVADDR,
 118		    arp_devaddr_compare(&arpinfo->src_devaddr, src_devaddr,
 119					dev->addr_len)) ||
 120	    NF_INVF(arpinfo, ARPT_INV_TGTDEVADDR,
 121		    arp_devaddr_compare(&arpinfo->tgt_devaddr, tgt_devaddr,
 122					dev->addr_len)))
 123		return 0;
 124
 125	if (NF_INVF(arpinfo, ARPT_INV_SRCIP,
 126		    (src_ipaddr & arpinfo->smsk.s_addr) != arpinfo->src.s_addr) ||
 127	    NF_INVF(arpinfo, ARPT_INV_TGTIP,
 128		    (tgt_ipaddr & arpinfo->tmsk.s_addr) != arpinfo->tgt.s_addr))
 129		return 0;
 130
 131	/* Look for ifname matches.  */
 132	ret = ifname_compare(indev, arpinfo->iniface, arpinfo->iniface_mask);
 133
 134	if (NF_INVF(arpinfo, ARPT_INV_VIA_IN, ret != 0))
 135		return 0;
 136
 137	ret = ifname_compare(outdev, arpinfo->outiface, arpinfo->outiface_mask);
 138
 139	if (NF_INVF(arpinfo, ARPT_INV_VIA_OUT, ret != 0))
 140		return 0;
 141
 142	return 1;
 143}
 144
 145static inline int arp_checkentry(const struct arpt_arp *arp)
 146{
 147	if (arp->flags & ~ARPT_F_MASK)
 148		return 0;
 149	if (arp->invflags & ~ARPT_INV_MASK)
 150		return 0;
 151
 152	return 1;
 153}
 154
 155static unsigned int
 156arpt_error(struct sk_buff *skb, const struct xt_action_param *par)
 157{
 158	net_err_ratelimited("arp_tables: error: '%s'\n",
 159			    (const char *)par->targinfo);
 160
 161	return NF_DROP;
 162}
 163
 164static inline const struct xt_entry_target *
 165arpt_get_target_c(const struct arpt_entry *e)
 166{
 167	return arpt_get_target((struct arpt_entry *)e);
 168}
 169
 170static inline struct arpt_entry *
 171get_entry(const void *base, unsigned int offset)
 172{
 173	return (struct arpt_entry *)(base + offset);
 174}
 175
 176static inline
 177struct arpt_entry *arpt_next_entry(const struct arpt_entry *entry)
 178{
 179	return (void *)entry + entry->next_offset;
 180}
 181
 182unsigned int arpt_do_table(void *priv,
 183			   struct sk_buff *skb,
 184			   const struct nf_hook_state *state)
 185{
 186	const struct xt_table *table = priv;
 187	unsigned int hook = state->hook;
 188	static const char nulldevname[IFNAMSIZ] __attribute__((aligned(sizeof(long))));
 189	unsigned int verdict = NF_DROP;
 190	const struct arphdr *arp;
 191	struct arpt_entry *e, **jumpstack;
 192	const char *indev, *outdev;
 193	const void *table_base;
 194	unsigned int cpu, stackidx = 0;
 195	const struct xt_table_info *private;
 196	struct xt_action_param acpar;
 197	unsigned int addend;
 198
 199	if (!pskb_may_pull(skb, arp_hdr_len(skb->dev)))
 200		return NF_DROP;
 201
 202	indev = state->in ? state->in->name : nulldevname;
 203	outdev = state->out ? state->out->name : nulldevname;
 204
 205	local_bh_disable();
 206	addend = xt_write_recseq_begin();
 207	private = READ_ONCE(table->private); /* Address dependency. */
 208	cpu     = smp_processor_id();
 209	table_base = private->entries;
 210	jumpstack  = (struct arpt_entry **)private->jumpstack[cpu];
 211
 212	/* No TEE support for arptables, so no need to switch to alternate
 213	 * stack.  All targets that reenter must return absolute verdicts.
 214	 */
 215	e = get_entry(table_base, private->hook_entry[hook]);
 216
 217	acpar.state   = state;
 218	acpar.hotdrop = false;
 219
 220	arp = arp_hdr(skb);
 221	do {
 222		const struct xt_entry_target *t;
 223		struct xt_counters *counter;
 224
 225		if (!arp_packet_match(arp, skb->dev, indev, outdev, &e->arp)) {
 226			e = arpt_next_entry(e);
 227			continue;
 228		}
 229
 230		counter = xt_get_this_cpu_counter(&e->counters);
 231		ADD_COUNTER(*counter, arp_hdr_len(skb->dev), 1);
 232
 233		t = arpt_get_target_c(e);
 234
 235		/* Standard target? */
 236		if (!t->u.kernel.target->target) {
 237			int v;
 238
 239			v = ((struct xt_standard_target *)t)->verdict;
 240			if (v < 0) {
 241				/* Pop from stack? */
 242				if (v != XT_RETURN) {
 243					verdict = (unsigned int)(-v) - 1;
 244					break;
 245				}
 246				if (stackidx == 0) {
 247					e = get_entry(table_base,
 248						      private->underflow[hook]);
 249				} else {
 250					e = jumpstack[--stackidx];
 251					e = arpt_next_entry(e);
 252				}
 253				continue;
 254			}
 255			if (table_base + v
 256			    != arpt_next_entry(e)) {
 257				if (unlikely(stackidx >= private->stacksize)) {
 258					verdict = NF_DROP;
 259					break;
 260				}
 261				jumpstack[stackidx++] = e;
 262			}
 263
 264			e = get_entry(table_base, v);
 265			continue;
 266		}
 267
 268		acpar.target   = t->u.kernel.target;
 269		acpar.targinfo = t->data;
 270		verdict = t->u.kernel.target->target(skb, &acpar);
 271
 272		if (verdict == XT_CONTINUE) {
 273			/* Target might have changed stuff. */
 274			arp = arp_hdr(skb);
 275			e = arpt_next_entry(e);
 276		} else {
 277			/* Verdict */
 278			break;
 279		}
 280	} while (!acpar.hotdrop);
 281	xt_write_recseq_end(addend);
 282	local_bh_enable();
 283
 284	if (acpar.hotdrop)
 285		return NF_DROP;
 286	else
 287		return verdict;
 288}
 289
 290/* All zeroes == unconditional rule. */
 291static inline bool unconditional(const struct arpt_entry *e)
 292{
 293	static const struct arpt_arp uncond;
 294
 295	return e->target_offset == sizeof(struct arpt_entry) &&
 296	       memcmp(&e->arp, &uncond, sizeof(uncond)) == 0;
 297}
 298
 299/* Figures out from what hook each rule can be called: returns 0 if
 300 * there are loops.  Puts hook bitmask in comefrom.
 301 */
 302static int mark_source_chains(const struct xt_table_info *newinfo,
 303			      unsigned int valid_hooks, void *entry0,
 304			      unsigned int *offsets)
 305{
 306	unsigned int hook;
 307
 308	/* No recursion; use packet counter to save back ptrs (reset
 309	 * to 0 as we leave), and comefrom to save source hook bitmask.
 310	 */
 311	for (hook = 0; hook < NF_ARP_NUMHOOKS; hook++) {
 312		unsigned int pos = newinfo->hook_entry[hook];
 313		struct arpt_entry *e = entry0 + pos;
 314
 315		if (!(valid_hooks & (1 << hook)))
 316			continue;
 317
 318		/* Set initial back pointer. */
 319		e->counters.pcnt = pos;
 320
 321		for (;;) {
 322			const struct xt_standard_target *t
 323				= (void *)arpt_get_target_c(e);
 324			int visited = e->comefrom & (1 << hook);
 325
 326			if (e->comefrom & (1 << NF_ARP_NUMHOOKS))
 327				return 0;
 328
 329			e->comefrom
 330				|= ((1 << hook) | (1 << NF_ARP_NUMHOOKS));
 331
 332			/* Unconditional return/END. */
 333			if ((unconditional(e) &&
 334			     (strcmp(t->target.u.user.name,
 335				     XT_STANDARD_TARGET) == 0) &&
 336			     t->verdict < 0) || visited) {
 337				unsigned int oldpos, size;
 338
 339				/* Return: backtrack through the last
 340				 * big jump.
 341				 */
 342				do {
 343					e->comefrom ^= (1<<NF_ARP_NUMHOOKS);
 344					oldpos = pos;
 345					pos = e->counters.pcnt;
 346					e->counters.pcnt = 0;
 347
 348					/* We're at the start. */
 349					if (pos == oldpos)
 350						goto next;
 351
 352					e = entry0 + pos;
 353				} while (oldpos == pos + e->next_offset);
 354
 355				/* Move along one */
 356				size = e->next_offset;
 357				e = entry0 + pos + size;
 358				if (pos + size >= newinfo->size)
 359					return 0;
 360				e->counters.pcnt = pos;
 361				pos += size;
 362			} else {
 363				int newpos = t->verdict;
 364
 365				if (strcmp(t->target.u.user.name,
 366					   XT_STANDARD_TARGET) == 0 &&
 367				    newpos >= 0) {
 368					/* This a jump; chase it. */
 369					if (!xt_find_jump_offset(offsets, newpos,
 370								 newinfo->number))
 371						return 0;
 372				} else {
 373					/* ... this is a fallthru */
 374					newpos = pos + e->next_offset;
 375					if (newpos >= newinfo->size)
 376						return 0;
 377				}
 378				e = entry0 + newpos;
 379				e->counters.pcnt = pos;
 380				pos = newpos;
 381			}
 382		}
 383next:		;
 384	}
 385	return 1;
 386}
 387
 388static int check_target(struct arpt_entry *e, struct net *net, const char *name)
 389{
 390	struct xt_entry_target *t = arpt_get_target(e);
 391	struct xt_tgchk_param par = {
 392		.net       = net,
 393		.table     = name,
 394		.entryinfo = e,
 395		.target    = t->u.kernel.target,
 396		.targinfo  = t->data,
 397		.hook_mask = e->comefrom,
 398		.family    = NFPROTO_ARP,
 399	};
 400
 401	return xt_check_target(&par, t->u.target_size - sizeof(*t), 0, false);
 402}
 403
 404static int
 405find_check_entry(struct arpt_entry *e, struct net *net, const char *name,
 406		 unsigned int size,
 407		 struct xt_percpu_counter_alloc_state *alloc_state)
 408{
 409	struct xt_entry_target *t;
 410	struct xt_target *target;
 411	int ret;
 412
 413	if (!xt_percpu_counter_alloc(alloc_state, &e->counters))
 414		return -ENOMEM;
 415
 416	t = arpt_get_target(e);
 417	target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
 418					t->u.user.revision);
 419	if (IS_ERR(target)) {
 420		ret = PTR_ERR(target);
 421		goto out;
 422	}
 423	t->u.kernel.target = target;
 424
 425	ret = check_target(e, net, name);
 426	if (ret)
 427		goto err;
 428	return 0;
 429err:
 430	module_put(t->u.kernel.target->me);
 431out:
 432	xt_percpu_counter_free(&e->counters);
 433
 434	return ret;
 435}
 436
 437static bool check_underflow(const struct arpt_entry *e)
 438{
 439	const struct xt_entry_target *t;
 440	unsigned int verdict;
 441
 442	if (!unconditional(e))
 443		return false;
 444	t = arpt_get_target_c(e);
 445	if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
 446		return false;
 447	verdict = ((struct xt_standard_target *)t)->verdict;
 448	verdict = -verdict - 1;
 449	return verdict == NF_DROP || verdict == NF_ACCEPT;
 450}
 451
 452static inline int check_entry_size_and_hooks(struct arpt_entry *e,
 453					     struct xt_table_info *newinfo,
 454					     const unsigned char *base,
 455					     const unsigned char *limit,
 456					     const unsigned int *hook_entries,
 457					     const unsigned int *underflows,
 458					     unsigned int valid_hooks)
 459{
 460	unsigned int h;
 461	int err;
 462
 463	if ((unsigned long)e % __alignof__(struct arpt_entry) != 0 ||
 464	    (unsigned char *)e + sizeof(struct arpt_entry) >= limit ||
 465	    (unsigned char *)e + e->next_offset > limit)
 466		return -EINVAL;
 467
 468	if (e->next_offset
 469	    < sizeof(struct arpt_entry) + sizeof(struct xt_entry_target))
 470		return -EINVAL;
 471
 472	if (!arp_checkentry(&e->arp))
 473		return -EINVAL;
 474
 475	err = xt_check_entry_offsets(e, e->elems, e->target_offset,
 476				     e->next_offset);
 477	if (err)
 478		return err;
 479
 480	/* Check hooks & underflows */
 481	for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
 482		if (!(valid_hooks & (1 << h)))
 483			continue;
 484		if ((unsigned char *)e - base == hook_entries[h])
 485			newinfo->hook_entry[h] = hook_entries[h];
 486		if ((unsigned char *)e - base == underflows[h]) {
 487			if (!check_underflow(e))
 488				return -EINVAL;
 489
 490			newinfo->underflow[h] = underflows[h];
 491		}
 492	}
 493
 494	/* Clear counters and comefrom */
 495	e->counters = ((struct xt_counters) { 0, 0 });
 496	e->comefrom = 0;
 497	return 0;
 498}
 499
 500static void cleanup_entry(struct arpt_entry *e, struct net *net)
 501{
 502	struct xt_tgdtor_param par;
 503	struct xt_entry_target *t;
 504
 505	t = arpt_get_target(e);
 506	par.net      = net;
 507	par.target   = t->u.kernel.target;
 508	par.targinfo = t->data;
 509	par.family   = NFPROTO_ARP;
 510	if (par.target->destroy != NULL)
 511		par.target->destroy(&par);
 512	module_put(par.target->me);
 513	xt_percpu_counter_free(&e->counters);
 514}
 515
 516/* Checks and translates the user-supplied table segment (held in
 517 * newinfo).
 518 */
 519static int translate_table(struct net *net,
 520			   struct xt_table_info *newinfo,
 521			   void *entry0,
 522			   const struct arpt_replace *repl)
 523{
 524	struct xt_percpu_counter_alloc_state alloc_state = { 0 };
 525	struct arpt_entry *iter;
 526	unsigned int *offsets;
 527	unsigned int i;
 528	int ret = 0;
 529
 530	newinfo->size = repl->size;
 531	newinfo->number = repl->num_entries;
 532
 533	/* Init all hooks to impossible value. */
 534	for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
 535		newinfo->hook_entry[i] = 0xFFFFFFFF;
 536		newinfo->underflow[i] = 0xFFFFFFFF;
 537	}
 538
 539	offsets = xt_alloc_entry_offsets(newinfo->number);
 540	if (!offsets)
 541		return -ENOMEM;
 542	i = 0;
 543
 544	/* Walk through entries, checking offsets. */
 545	xt_entry_foreach(iter, entry0, newinfo->size) {
 546		ret = check_entry_size_and_hooks(iter, newinfo, entry0,
 547						 entry0 + repl->size,
 548						 repl->hook_entry,
 549						 repl->underflow,
 550						 repl->valid_hooks);
 551		if (ret != 0)
 552			goto out_free;
 553		if (i < repl->num_entries)
 554			offsets[i] = (void *)iter - entry0;
 555		++i;
 556		if (strcmp(arpt_get_target(iter)->u.user.name,
 557		    XT_ERROR_TARGET) == 0)
 558			++newinfo->stacksize;
 559	}
 560
 561	ret = -EINVAL;
 562	if (i != repl->num_entries)
 563		goto out_free;
 564
 565	ret = xt_check_table_hooks(newinfo, repl->valid_hooks);
 566	if (ret)
 567		goto out_free;
 568
 569	if (!mark_source_chains(newinfo, repl->valid_hooks, entry0, offsets)) {
 570		ret = -ELOOP;
 571		goto out_free;
 572	}
 573	kvfree(offsets);
 574
 575	/* Finally, each sanity check must pass */
 576	i = 0;
 577	xt_entry_foreach(iter, entry0, newinfo->size) {
 578		ret = find_check_entry(iter, net, repl->name, repl->size,
 579				       &alloc_state);
 580		if (ret != 0)
 581			break;
 582		++i;
 583	}
 584
 585	if (ret != 0) {
 586		xt_entry_foreach(iter, entry0, newinfo->size) {
 587			if (i-- == 0)
 588				break;
 589			cleanup_entry(iter, net);
 590		}
 591		return ret;
 592	}
 593
 594	return ret;
 595 out_free:
 596	kvfree(offsets);
 597	return ret;
 598}
 599
 600static void get_counters(const struct xt_table_info *t,
 601			 struct xt_counters counters[])
 602{
 603	struct arpt_entry *iter;
 604	unsigned int cpu;
 605	unsigned int i;
 606
 607	for_each_possible_cpu(cpu) {
 608		seqcount_t *s = &per_cpu(xt_recseq, cpu);
 609
 610		i = 0;
 611		xt_entry_foreach(iter, t->entries, t->size) {
 612			struct xt_counters *tmp;
 613			u64 bcnt, pcnt;
 614			unsigned int start;
 615
 616			tmp = xt_get_per_cpu_counter(&iter->counters, cpu);
 617			do {
 618				start = read_seqcount_begin(s);
 619				bcnt = tmp->bcnt;
 620				pcnt = tmp->pcnt;
 621			} while (read_seqcount_retry(s, start));
 622
 623			ADD_COUNTER(counters[i], bcnt, pcnt);
 624			++i;
 625			cond_resched();
 626		}
 627	}
 628}
 629
 630static void get_old_counters(const struct xt_table_info *t,
 631			     struct xt_counters counters[])
 632{
 633	struct arpt_entry *iter;
 634	unsigned int cpu, i;
 635
 636	for_each_possible_cpu(cpu) {
 637		i = 0;
 638		xt_entry_foreach(iter, t->entries, t->size) {
 639			struct xt_counters *tmp;
 640
 641			tmp = xt_get_per_cpu_counter(&iter->counters, cpu);
 642			ADD_COUNTER(counters[i], tmp->bcnt, tmp->pcnt);
 643			++i;
 644		}
 645		cond_resched();
 646	}
 647}
 648
 649static struct xt_counters *alloc_counters(const struct xt_table *table)
 650{
 651	unsigned int countersize;
 652	struct xt_counters *counters;
 653	const struct xt_table_info *private = table->private;
 654
 655	/* We need atomic snapshot of counters: rest doesn't change
 656	 * (other than comefrom, which userspace doesn't care
 657	 * about).
 658	 */
 659	countersize = sizeof(struct xt_counters) * private->number;
 660	counters = vzalloc(countersize);
 661
 662	if (counters == NULL)
 663		return ERR_PTR(-ENOMEM);
 664
 665	get_counters(private, counters);
 666
 667	return counters;
 668}
 669
 670static int copy_entries_to_user(unsigned int total_size,
 671				const struct xt_table *table,
 672				void __user *userptr)
 673{
 674	unsigned int off, num;
 675	const struct arpt_entry *e;
 676	struct xt_counters *counters;
 677	struct xt_table_info *private = table->private;
 678	int ret = 0;
 679	void *loc_cpu_entry;
 680
 681	counters = alloc_counters(table);
 682	if (IS_ERR(counters))
 683		return PTR_ERR(counters);
 684
 685	loc_cpu_entry = private->entries;
 686
 687	/* FIXME: use iterator macros --RR */
 688	/* ... then go back and fix counters and names */
 689	for (off = 0, num = 0; off < total_size; off += e->next_offset, num++){
 690		const struct xt_entry_target *t;
 691
 692		e = loc_cpu_entry + off;
 693		if (copy_to_user(userptr + off, e, sizeof(*e))) {
 694			ret = -EFAULT;
 695			goto free_counters;
 696		}
 697		if (copy_to_user(userptr + off
 698				 + offsetof(struct arpt_entry, counters),
 699				 &counters[num],
 700				 sizeof(counters[num])) != 0) {
 701			ret = -EFAULT;
 702			goto free_counters;
 703		}
 704
 705		t = arpt_get_target_c(e);
 706		if (xt_target_to_user(t, userptr + off + e->target_offset)) {
 707			ret = -EFAULT;
 708			goto free_counters;
 709		}
 710	}
 711
 712 free_counters:
 713	vfree(counters);
 714	return ret;
 715}
 716
 717#ifdef CONFIG_NETFILTER_XTABLES_COMPAT
 718static void compat_standard_from_user(void *dst, const void *src)
 719{
 720	int v = *(compat_int_t *)src;
 721
 722	if (v > 0)
 723		v += xt_compat_calc_jump(NFPROTO_ARP, v);
 724	memcpy(dst, &v, sizeof(v));
 725}
 726
 727static int compat_standard_to_user(void __user *dst, const void *src)
 728{
 729	compat_int_t cv = *(int *)src;
 730
 731	if (cv > 0)
 732		cv -= xt_compat_calc_jump(NFPROTO_ARP, cv);
 733	return copy_to_user(dst, &cv, sizeof(cv)) ? -EFAULT : 0;
 734}
 735
 736static int compat_calc_entry(const struct arpt_entry *e,
 737			     const struct xt_table_info *info,
 738			     const void *base, struct xt_table_info *newinfo)
 739{
 740	const struct xt_entry_target *t;
 741	unsigned int entry_offset;
 742	int off, i, ret;
 743
 744	off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
 745	entry_offset = (void *)e - base;
 746
 747	t = arpt_get_target_c(e);
 748	off += xt_compat_target_offset(t->u.kernel.target);
 749	newinfo->size -= off;
 750	ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
 751	if (ret)
 752		return ret;
 753
 754	for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
 755		if (info->hook_entry[i] &&
 756		    (e < (struct arpt_entry *)(base + info->hook_entry[i])))
 757			newinfo->hook_entry[i] -= off;
 758		if (info->underflow[i] &&
 759		    (e < (struct arpt_entry *)(base + info->underflow[i])))
 760			newinfo->underflow[i] -= off;
 761	}
 762	return 0;
 763}
 764
 765static int compat_table_info(const struct xt_table_info *info,
 766			     struct xt_table_info *newinfo)
 767{
 768	struct arpt_entry *iter;
 769	const void *loc_cpu_entry;
 770	int ret;
 771
 772	if (!newinfo || !info)
 773		return -EINVAL;
 774
 775	/* we dont care about newinfo->entries */
 776	memcpy(newinfo, info, offsetof(struct xt_table_info, entries));
 777	newinfo->initial_entries = 0;
 778	loc_cpu_entry = info->entries;
 779	ret = xt_compat_init_offsets(NFPROTO_ARP, info->number);
 780	if (ret)
 781		return ret;
 782	xt_entry_foreach(iter, loc_cpu_entry, info->size) {
 783		ret = compat_calc_entry(iter, info, loc_cpu_entry, newinfo);
 784		if (ret != 0)
 785			return ret;
 786	}
 787	return 0;
 788}
 789#endif
 790
 791static int get_info(struct net *net, void __user *user, const int *len)
 792{
 793	char name[XT_TABLE_MAXNAMELEN];
 794	struct xt_table *t;
 795	int ret;
 796
 797	if (*len != sizeof(struct arpt_getinfo))
 798		return -EINVAL;
 799
 800	if (copy_from_user(name, user, sizeof(name)) != 0)
 801		return -EFAULT;
 802
 803	name[XT_TABLE_MAXNAMELEN-1] = '\0';
 804#ifdef CONFIG_NETFILTER_XTABLES_COMPAT
 805	if (in_compat_syscall())
 806		xt_compat_lock(NFPROTO_ARP);
 807#endif
 808	t = xt_request_find_table_lock(net, NFPROTO_ARP, name);
 809	if (!IS_ERR(t)) {
 810		struct arpt_getinfo info;
 811		const struct xt_table_info *private = t->private;
 812#ifdef CONFIG_NETFILTER_XTABLES_COMPAT
 813		struct xt_table_info tmp;
 814
 815		if (in_compat_syscall()) {
 816			ret = compat_table_info(private, &tmp);
 817			xt_compat_flush_offsets(NFPROTO_ARP);
 818			private = &tmp;
 819		}
 820#endif
 821		memset(&info, 0, sizeof(info));
 822		info.valid_hooks = t->valid_hooks;
 823		memcpy(info.hook_entry, private->hook_entry,
 824		       sizeof(info.hook_entry));
 825		memcpy(info.underflow, private->underflow,
 826		       sizeof(info.underflow));
 827		info.num_entries = private->number;
 828		info.size = private->size;
 829		strscpy(info.name, name);
 830
 831		if (copy_to_user(user, &info, *len) != 0)
 832			ret = -EFAULT;
 833		else
 834			ret = 0;
 835		xt_table_unlock(t);
 836		module_put(t->me);
 837	} else
 838		ret = PTR_ERR(t);
 839#ifdef CONFIG_NETFILTER_XTABLES_COMPAT
 840	if (in_compat_syscall())
 841		xt_compat_unlock(NFPROTO_ARP);
 842#endif
 843	return ret;
 844}
 845
 846static int get_entries(struct net *net, struct arpt_get_entries __user *uptr,
 847		       const int *len)
 848{
 849	int ret;
 850	struct arpt_get_entries get;
 851	struct xt_table *t;
 852
 853	if (*len < sizeof(get))
 854		return -EINVAL;
 855	if (copy_from_user(&get, uptr, sizeof(get)) != 0)
 856		return -EFAULT;
 857	if (*len != sizeof(struct arpt_get_entries) + get.size)
 858		return -EINVAL;
 859
 860	get.name[sizeof(get.name) - 1] = '\0';
 861
 862	t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
 863	if (!IS_ERR(t)) {
 864		const struct xt_table_info *private = t->private;
 865
 866		if (get.size == private->size)
 867			ret = copy_entries_to_user(private->size,
 868						   t, uptr->entrytable);
 869		else
 870			ret = -EAGAIN;
 871
 872		module_put(t->me);
 873		xt_table_unlock(t);
 874	} else
 875		ret = PTR_ERR(t);
 876
 877	return ret;
 878}
 879
 880static int __do_replace(struct net *net, const char *name,
 881			unsigned int valid_hooks,
 882			struct xt_table_info *newinfo,
 883			unsigned int num_counters,
 884			void __user *counters_ptr)
 885{
 886	int ret;
 887	struct xt_table *t;
 888	struct xt_table_info *oldinfo;
 889	struct xt_counters *counters;
 890	void *loc_cpu_old_entry;
 891	struct arpt_entry *iter;
 892
 893	ret = 0;
 894	counters = xt_counters_alloc(num_counters);
 895	if (!counters) {
 896		ret = -ENOMEM;
 897		goto out;
 898	}
 899
 900	t = xt_request_find_table_lock(net, NFPROTO_ARP, name);
 901	if (IS_ERR(t)) {
 902		ret = PTR_ERR(t);
 903		goto free_newinfo_counters_untrans;
 904	}
 905
 906	/* You lied! */
 907	if (valid_hooks != t->valid_hooks) {
 908		ret = -EINVAL;
 909		goto put_module;
 910	}
 911
 912	oldinfo = xt_replace_table(t, num_counters, newinfo, &ret);
 913	if (!oldinfo)
 914		goto put_module;
 915
 916	/* Update module usage count based on number of rules */
 917	if ((oldinfo->number > oldinfo->initial_entries) ||
 918	    (newinfo->number <= oldinfo->initial_entries))
 919		module_put(t->me);
 920	if ((oldinfo->number > oldinfo->initial_entries) &&
 921	    (newinfo->number <= oldinfo->initial_entries))
 922		module_put(t->me);
 923
 924	xt_table_unlock(t);
 925
 926	get_old_counters(oldinfo, counters);
 927
 928	/* Decrease module usage counts and free resource */
 929	loc_cpu_old_entry = oldinfo->entries;
 930	xt_entry_foreach(iter, loc_cpu_old_entry, oldinfo->size)
 931		cleanup_entry(iter, net);
 932
 933	xt_free_table_info(oldinfo);
 934	if (copy_to_user(counters_ptr, counters,
 935			 sizeof(struct xt_counters) * num_counters) != 0) {
 936		/* Silent error, can't fail, new table is already in place */
 937		net_warn_ratelimited("arptables: counters copy to user failed while replacing table\n");
 938	}
 939	vfree(counters);
 940	return ret;
 941
 942 put_module:
 943	module_put(t->me);
 944	xt_table_unlock(t);
 945 free_newinfo_counters_untrans:
 946	vfree(counters);
 947 out:
 948	return ret;
 949}
 950
 951static int do_replace(struct net *net, sockptr_t arg, unsigned int len)
 952{
 953	int ret;
 954	struct arpt_replace tmp;
 955	struct xt_table_info *newinfo;
 956	void *loc_cpu_entry;
 957	struct arpt_entry *iter;
 958
 959	if (len < sizeof(tmp))
 960		return -EINVAL;
 961	if (copy_from_sockptr(&tmp, arg, sizeof(tmp)) != 0)
 962		return -EFAULT;
 963
 964	/* overflow check */
 965	if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
 966		return -ENOMEM;
 967	if (tmp.num_counters == 0)
 968		return -EINVAL;
 969	if ((u64)len < (u64)tmp.size + sizeof(tmp))
 970		return -EINVAL;
 971
 972	tmp.name[sizeof(tmp.name)-1] = 0;
 973
 974	newinfo = xt_alloc_table_info(tmp.size);
 975	if (!newinfo)
 976		return -ENOMEM;
 977
 978	loc_cpu_entry = newinfo->entries;
 979	if (copy_from_sockptr_offset(loc_cpu_entry, arg, sizeof(tmp),
 980			tmp.size) != 0) {
 981		ret = -EFAULT;
 982		goto free_newinfo;
 983	}
 984
 985	ret = translate_table(net, newinfo, loc_cpu_entry, &tmp);
 986	if (ret != 0)
 987		goto free_newinfo;
 988
 989	ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
 990			   tmp.num_counters, tmp.counters);
 991	if (ret)
 992		goto free_newinfo_untrans;
 993	return 0;
 994
 995 free_newinfo_untrans:
 996	xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
 997		cleanup_entry(iter, net);
 998 free_newinfo:
 999	xt_free_table_info(newinfo);
1000	return ret;
1001}
1002
1003static int do_add_counters(struct net *net, sockptr_t arg, unsigned int len)
1004{
1005	unsigned int i;
1006	struct xt_counters_info tmp;
1007	struct xt_counters *paddc;
1008	struct xt_table *t;
1009	const struct xt_table_info *private;
1010	int ret = 0;
1011	struct arpt_entry *iter;
1012	unsigned int addend;
1013
1014	paddc = xt_copy_counters(arg, len, &tmp);
1015	if (IS_ERR(paddc))
1016		return PTR_ERR(paddc);
1017
1018	t = xt_find_table_lock(net, NFPROTO_ARP, tmp.name);
1019	if (IS_ERR(t)) {
1020		ret = PTR_ERR(t);
1021		goto free;
1022	}
1023
1024	local_bh_disable();
1025	private = t->private;
1026	if (private->number != tmp.num_counters) {
1027		ret = -EINVAL;
1028		goto unlock_up_free;
1029	}
1030
1031	i = 0;
1032
1033	addend = xt_write_recseq_begin();
1034	xt_entry_foreach(iter,  private->entries, private->size) {
1035		struct xt_counters *tmp;
1036
1037		tmp = xt_get_this_cpu_counter(&iter->counters);
1038		ADD_COUNTER(*tmp, paddc[i].bcnt, paddc[i].pcnt);
1039		++i;
1040	}
1041	xt_write_recseq_end(addend);
1042 unlock_up_free:
1043	local_bh_enable();
1044	xt_table_unlock(t);
1045	module_put(t->me);
1046 free:
1047	vfree(paddc);
1048
1049	return ret;
1050}
1051
1052#ifdef CONFIG_NETFILTER_XTABLES_COMPAT
1053struct compat_arpt_replace {
1054	char				name[XT_TABLE_MAXNAMELEN];
1055	u32				valid_hooks;
1056	u32				num_entries;
1057	u32				size;
1058	u32				hook_entry[NF_ARP_NUMHOOKS];
1059	u32				underflow[NF_ARP_NUMHOOKS];
1060	u32				num_counters;
1061	compat_uptr_t			counters;
1062	struct compat_arpt_entry	entries[];
1063};
1064
1065static inline void compat_release_entry(struct compat_arpt_entry *e)
1066{
1067	struct xt_entry_target *t;
1068
1069	t = compat_arpt_get_target(e);
1070	module_put(t->u.kernel.target->me);
1071}
1072
1073static int
1074check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
1075				  struct xt_table_info *newinfo,
1076				  unsigned int *size,
1077				  const unsigned char *base,
1078				  const unsigned char *limit)
1079{
1080	struct xt_entry_target *t;
1081	struct xt_target *target;
1082	unsigned int entry_offset;
1083	int ret, off;
1084
1085	if ((unsigned long)e % __alignof__(struct compat_arpt_entry) != 0 ||
1086	    (unsigned char *)e + sizeof(struct compat_arpt_entry) >= limit ||
1087	    (unsigned char *)e + e->next_offset > limit)
1088		return -EINVAL;
1089
1090	if (e->next_offset < sizeof(struct compat_arpt_entry) +
1091			     sizeof(struct compat_xt_entry_target))
1092		return -EINVAL;
1093
1094	if (!arp_checkentry(&e->arp))
1095		return -EINVAL;
1096
1097	ret = xt_compat_check_entry_offsets(e, e->elems, e->target_offset,
1098					    e->next_offset);
1099	if (ret)
1100		return ret;
1101
1102	off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1103	entry_offset = (void *)e - (void *)base;
1104
1105	t = compat_arpt_get_target(e);
1106	target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
1107					t->u.user.revision);
1108	if (IS_ERR(target)) {
1109		ret = PTR_ERR(target);
1110		goto out;
1111	}
1112	t->u.kernel.target = target;
1113
1114	off += xt_compat_target_offset(target);
1115	*size += off;
1116	ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
1117	if (ret)
1118		goto release_target;
1119
1120	return 0;
1121
1122release_target:
1123	module_put(t->u.kernel.target->me);
1124out:
1125	return ret;
1126}
1127
1128static void
1129compat_copy_entry_from_user(struct compat_arpt_entry *e, void **dstptr,
1130			    unsigned int *size,
1131			    struct xt_table_info *newinfo, unsigned char *base)
1132{
1133	struct xt_entry_target *t;
1134	struct arpt_entry *de;
1135	unsigned int origsize;
1136	int h;
1137
1138	origsize = *size;
1139	de = *dstptr;
1140	memcpy(de, e, sizeof(struct arpt_entry));
1141	memcpy(&de->counters, &e->counters, sizeof(e->counters));
1142
1143	*dstptr += sizeof(struct arpt_entry);
1144	*size += sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1145
1146	de->target_offset = e->target_offset - (origsize - *size);
1147	t = compat_arpt_get_target(e);
1148	xt_compat_target_from_user(t, dstptr, size);
1149
1150	de->next_offset = e->next_offset - (origsize - *size);
1151	for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
1152		if ((unsigned char *)de - base < newinfo->hook_entry[h])
1153			newinfo->hook_entry[h] -= origsize - *size;
1154		if ((unsigned char *)de - base < newinfo->underflow[h])
1155			newinfo->underflow[h] -= origsize - *size;
1156	}
1157}
1158
1159static int translate_compat_table(struct net *net,
1160				  struct xt_table_info **pinfo,
1161				  void **pentry0,
1162				  const struct compat_arpt_replace *compatr)
1163{
1164	unsigned int i, j;
1165	struct xt_table_info *newinfo, *info;
1166	void *pos, *entry0, *entry1;
1167	struct compat_arpt_entry *iter0;
1168	struct arpt_replace repl;
1169	unsigned int size;
1170	int ret;
1171
1172	info = *pinfo;
1173	entry0 = *pentry0;
1174	size = compatr->size;
1175	info->number = compatr->num_entries;
1176
1177	j = 0;
1178	xt_compat_lock(NFPROTO_ARP);
1179	ret = xt_compat_init_offsets(NFPROTO_ARP, compatr->num_entries);
1180	if (ret)
1181		goto out_unlock;
1182	/* Walk through entries, checking offsets. */
1183	xt_entry_foreach(iter0, entry0, compatr->size) {
1184		ret = check_compat_entry_size_and_hooks(iter0, info, &size,
1185							entry0,
1186							entry0 + compatr->size);
1187		if (ret != 0)
1188			goto out_unlock;
1189		++j;
1190	}
1191
1192	ret = -EINVAL;
1193	if (j != compatr->num_entries)
1194		goto out_unlock;
1195
1196	ret = -ENOMEM;
1197	newinfo = xt_alloc_table_info(size);
1198	if (!newinfo)
1199		goto out_unlock;
1200
1201	memset(newinfo->entries, 0, size);
1202
1203	newinfo->number = compatr->num_entries;
1204	for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1205		newinfo->hook_entry[i] = compatr->hook_entry[i];
1206		newinfo->underflow[i] = compatr->underflow[i];
1207	}
1208	entry1 = newinfo->entries;
1209	pos = entry1;
1210	size = compatr->size;
1211	xt_entry_foreach(iter0, entry0, compatr->size)
1212		compat_copy_entry_from_user(iter0, &pos, &size,
1213					    newinfo, entry1);
1214
1215	/* all module references in entry0 are now gone */
1216
1217	xt_compat_flush_offsets(NFPROTO_ARP);
1218	xt_compat_unlock(NFPROTO_ARP);
1219
1220	memcpy(&repl, compatr, sizeof(*compatr));
1221
1222	for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
1223		repl.hook_entry[i] = newinfo->hook_entry[i];
1224		repl.underflow[i] = newinfo->underflow[i];
1225	}
1226
1227	repl.num_counters = 0;
1228	repl.counters = NULL;
1229	repl.size = newinfo->size;
1230	ret = translate_table(net, newinfo, entry1, &repl);
1231	if (ret)
1232		goto free_newinfo;
1233
1234	*pinfo = newinfo;
1235	*pentry0 = entry1;
1236	xt_free_table_info(info);
1237	return 0;
1238
1239free_newinfo:
1240	xt_free_table_info(newinfo);
1241	return ret;
1242out_unlock:
1243	xt_compat_flush_offsets(NFPROTO_ARP);
1244	xt_compat_unlock(NFPROTO_ARP);
1245	xt_entry_foreach(iter0, entry0, compatr->size) {
1246		if (j-- == 0)
1247			break;
1248		compat_release_entry(iter0);
1249	}
1250	return ret;
1251}
1252
1253static int compat_do_replace(struct net *net, sockptr_t arg, 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 (len < sizeof(tmp))
1262		return -EINVAL;
1263	if (copy_from_sockptr(&tmp, arg, sizeof(tmp)) != 0)
1264		return -EFAULT;
1265
1266	/* overflow check */
1267	if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
1268		return -ENOMEM;
1269	if (tmp.num_counters == 0)
1270		return -EINVAL;
1271	if ((u64)len < (u64)tmp.size + sizeof(tmp))
1272		return -EINVAL;
1273
1274	tmp.name[sizeof(tmp.name)-1] = 0;
1275
1276	newinfo = xt_alloc_table_info(tmp.size);
1277	if (!newinfo)
1278		return -ENOMEM;
1279
1280	loc_cpu_entry = newinfo->entries;
1281	if (copy_from_sockptr_offset(loc_cpu_entry, arg, sizeof(tmp),
1282			tmp.size) != 0) {
1283		ret = -EFAULT;
1284		goto free_newinfo;
1285	}
1286
1287	ret = translate_compat_table(net, &newinfo, &loc_cpu_entry, &tmp);
1288	if (ret != 0)
1289		goto free_newinfo;
1290
1291	ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
1292			   tmp.num_counters, compat_ptr(tmp.counters));
1293	if (ret)
1294		goto free_newinfo_untrans;
1295	return 0;
1296
1297 free_newinfo_untrans:
1298	xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
1299		cleanup_entry(iter, net);
1300 free_newinfo:
1301	xt_free_table_info(newinfo);
1302	return ret;
1303}
1304
1305static int compat_copy_entry_to_user(struct arpt_entry *e, void __user **dstptr,
1306				     compat_uint_t *size,
1307				     struct xt_counters *counters,
1308				     unsigned int i)
1309{
1310	struct xt_entry_target *t;
1311	struct compat_arpt_entry __user *ce;
1312	u_int16_t target_offset, next_offset;
1313	compat_uint_t origsize;
1314	int ret;
1315
1316	origsize = *size;
1317	ce = *dstptr;
1318	if (copy_to_user(ce, e, sizeof(struct arpt_entry)) != 0 ||
1319	    copy_to_user(&ce->counters, &counters[i],
1320	    sizeof(counters[i])) != 0)
1321		return -EFAULT;
1322
1323	*dstptr += sizeof(struct compat_arpt_entry);
1324	*size -= sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
1325
1326	target_offset = e->target_offset - (origsize - *size);
1327
1328	t = arpt_get_target(e);
1329	ret = xt_compat_target_to_user(t, dstptr, size);
1330	if (ret)
1331		return ret;
1332	next_offset = e->next_offset - (origsize - *size);
1333	if (put_user(target_offset, &ce->target_offset) != 0 ||
1334	    put_user(next_offset, &ce->next_offset) != 0)
1335		return -EFAULT;
1336	return 0;
1337}
1338
1339static int compat_copy_entries_to_user(unsigned int total_size,
1340				       struct xt_table *table,
1341				       void __user *userptr)
1342{
1343	struct xt_counters *counters;
1344	const struct xt_table_info *private = table->private;
1345	void __user *pos;
1346	unsigned int size;
1347	int ret = 0;
1348	unsigned int i = 0;
1349	struct arpt_entry *iter;
1350
1351	counters = alloc_counters(table);
1352	if (IS_ERR(counters))
1353		return PTR_ERR(counters);
1354
1355	pos = userptr;
1356	size = total_size;
1357	xt_entry_foreach(iter, private->entries, total_size) {
1358		ret = compat_copy_entry_to_user(iter, &pos,
1359						&size, counters, i++);
1360		if (ret != 0)
1361			break;
1362	}
1363	vfree(counters);
1364	return ret;
1365}
1366
1367struct compat_arpt_get_entries {
1368	char name[XT_TABLE_MAXNAMELEN];
1369	compat_uint_t size;
1370	struct compat_arpt_entry entrytable[];
1371};
1372
1373static int compat_get_entries(struct net *net,
1374			      struct compat_arpt_get_entries __user *uptr,
1375			      int *len)
1376{
1377	int ret;
1378	struct compat_arpt_get_entries get;
1379	struct xt_table *t;
1380
1381	if (*len < sizeof(get))
1382		return -EINVAL;
1383	if (copy_from_user(&get, uptr, sizeof(get)) != 0)
1384		return -EFAULT;
1385	if (*len != sizeof(struct compat_arpt_get_entries) + get.size)
1386		return -EINVAL;
1387
1388	get.name[sizeof(get.name) - 1] = '\0';
1389
1390	xt_compat_lock(NFPROTO_ARP);
1391	t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
1392	if (!IS_ERR(t)) {
1393		const struct xt_table_info *private = t->private;
1394		struct xt_table_info info;
1395
1396		ret = compat_table_info(private, &info);
1397		if (!ret && get.size == info.size) {
1398			ret = compat_copy_entries_to_user(private->size,
1399							  t, uptr->entrytable);
1400		} else if (!ret)
1401			ret = -EAGAIN;
1402
1403		xt_compat_flush_offsets(NFPROTO_ARP);
1404		module_put(t->me);
1405		xt_table_unlock(t);
1406	} else
1407		ret = PTR_ERR(t);
1408
1409	xt_compat_unlock(NFPROTO_ARP);
1410	return ret;
1411}
1412#endif
1413
1414static int do_arpt_set_ctl(struct sock *sk, int cmd, sockptr_t arg,
1415		unsigned int len)
1416{
1417	int ret;
1418
1419	if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1420		return -EPERM;
1421
1422	switch (cmd) {
1423	case ARPT_SO_SET_REPLACE:
1424#ifdef CONFIG_NETFILTER_XTABLES_COMPAT
1425		if (in_compat_syscall())
1426			ret = compat_do_replace(sock_net(sk), arg, len);
1427		else
1428#endif
1429			ret = do_replace(sock_net(sk), arg, len);
1430		break;
1431
1432	case ARPT_SO_SET_ADD_COUNTERS:
1433		ret = do_add_counters(sock_net(sk), arg, len);
1434		break;
1435
1436	default:
1437		ret = -EINVAL;
1438	}
1439
1440	return ret;
1441}
1442
1443static int do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
1444{
1445	int ret;
1446
1447	if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
1448		return -EPERM;
1449
1450	switch (cmd) {
1451	case ARPT_SO_GET_INFO:
1452		ret = get_info(sock_net(sk), user, len);
1453		break;
1454
1455	case ARPT_SO_GET_ENTRIES:
1456#ifdef CONFIG_NETFILTER_XTABLES_COMPAT
1457		if (in_compat_syscall())
1458			ret = compat_get_entries(sock_net(sk), user, len);
1459		else
1460#endif
1461			ret = get_entries(sock_net(sk), user, len);
1462		break;
1463
1464	case ARPT_SO_GET_REVISION_TARGET: {
1465		struct xt_get_revision rev;
1466
1467		if (*len != sizeof(rev)) {
1468			ret = -EINVAL;
1469			break;
1470		}
1471		if (copy_from_user(&rev, user, sizeof(rev)) != 0) {
1472			ret = -EFAULT;
1473			break;
1474		}
1475		rev.name[sizeof(rev.name)-1] = 0;
1476
1477		try_then_request_module(xt_find_revision(NFPROTO_ARP, rev.name,
1478							 rev.revision, 1, &ret),
1479					"arpt_%s", rev.name);
1480		break;
1481	}
1482
1483	default:
1484		ret = -EINVAL;
1485	}
1486
1487	return ret;
1488}
1489
1490static void __arpt_unregister_table(struct net *net, struct xt_table *table)
1491{
1492	struct xt_table_info *private;
1493	void *loc_cpu_entry;
1494	struct module *table_owner = table->me;
1495	struct arpt_entry *iter;
1496
1497	private = xt_unregister_table(table);
1498
1499	/* Decrease module usage counts and free resources */
1500	loc_cpu_entry = private->entries;
1501	xt_entry_foreach(iter, loc_cpu_entry, private->size)
1502		cleanup_entry(iter, net);
1503	if (private->number > private->initial_entries)
1504		module_put(table_owner);
1505	xt_free_table_info(private);
1506}
1507
1508int arpt_register_table(struct net *net,
1509			const struct xt_table *table,
1510			const struct arpt_replace *repl,
1511			const struct nf_hook_ops *template_ops)
1512{
1513	struct nf_hook_ops *ops;
1514	unsigned int num_ops;
1515	int ret, i;
1516	struct xt_table_info *newinfo;
1517	struct xt_table_info bootstrap = {0};
1518	void *loc_cpu_entry;
1519	struct xt_table *new_table;
1520
1521	newinfo = xt_alloc_table_info(repl->size);
1522	if (!newinfo)
1523		return -ENOMEM;
1524
1525	loc_cpu_entry = newinfo->entries;
1526	memcpy(loc_cpu_entry, repl->entries, repl->size);
1527
1528	ret = translate_table(net, newinfo, loc_cpu_entry, repl);
1529	if (ret != 0) {
1530		xt_free_table_info(newinfo);
1531		return ret;
1532	}
1533
1534	new_table = xt_register_table(net, table, &bootstrap, newinfo);
1535	if (IS_ERR(new_table)) {
1536		struct arpt_entry *iter;
1537
1538		xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
1539			cleanup_entry(iter, net);
1540		xt_free_table_info(newinfo);
1541		return PTR_ERR(new_table);
1542	}
1543
1544	num_ops = hweight32(table->valid_hooks);
1545	if (num_ops == 0) {
1546		ret = -EINVAL;
1547		goto out_free;
1548	}
1549
1550	ops = kmemdup_array(template_ops, num_ops, sizeof(*ops), GFP_KERNEL);
1551	if (!ops) {
1552		ret = -ENOMEM;
1553		goto out_free;
1554	}
1555
1556	for (i = 0; i < num_ops; i++)
1557		ops[i].priv = new_table;
1558
1559	new_table->ops = ops;
1560
1561	ret = nf_register_net_hooks(net, ops, num_ops);
1562	if (ret != 0)
1563		goto out_free;
1564
1565	return ret;
1566
1567out_free:
1568	__arpt_unregister_table(net, new_table);
1569	return ret;
1570}
1571
1572void arpt_unregister_table_pre_exit(struct net *net, const char *name)
1573{
1574	struct xt_table *table = xt_find_table(net, NFPROTO_ARP, name);
1575
1576	if (table)
1577		nf_unregister_net_hooks(net, table->ops, hweight32(table->valid_hooks));
1578}
1579EXPORT_SYMBOL(arpt_unregister_table_pre_exit);
1580
1581void arpt_unregister_table(struct net *net, const char *name)
1582{
1583	struct xt_table *table = xt_find_table(net, NFPROTO_ARP, name);
1584
1585	if (table)
1586		__arpt_unregister_table(net, table);
1587}
1588
1589/* The built-in targets: standard (NULL) and error. */
1590static struct xt_target arpt_builtin_tg[] __read_mostly = {
1591	{
1592		.name             = XT_STANDARD_TARGET,
1593		.targetsize       = sizeof(int),
1594		.family           = NFPROTO_ARP,
1595#ifdef CONFIG_NETFILTER_XTABLES_COMPAT
1596		.compatsize       = sizeof(compat_int_t),
1597		.compat_from_user = compat_standard_from_user,
1598		.compat_to_user   = compat_standard_to_user,
1599#endif
1600	},
1601	{
1602		.name             = XT_ERROR_TARGET,
1603		.target           = arpt_error,
1604		.targetsize       = XT_FUNCTION_MAXNAMELEN,
1605		.family           = NFPROTO_ARP,
1606	},
1607};
1608
1609static struct nf_sockopt_ops arpt_sockopts = {
1610	.pf		= PF_INET,
1611	.set_optmin	= ARPT_BASE_CTL,
1612	.set_optmax	= ARPT_SO_SET_MAX+1,
1613	.set		= do_arpt_set_ctl,
1614	.get_optmin	= ARPT_BASE_CTL,
1615	.get_optmax	= ARPT_SO_GET_MAX+1,
1616	.get		= do_arpt_get_ctl,
1617	.owner		= THIS_MODULE,
1618};
1619
1620static int __net_init arp_tables_net_init(struct net *net)
1621{
1622	return xt_proto_init(net, NFPROTO_ARP);
1623}
1624
1625static void __net_exit arp_tables_net_exit(struct net *net)
1626{
1627	xt_proto_fini(net, NFPROTO_ARP);
1628}
1629
1630static struct pernet_operations arp_tables_net_ops = {
1631	.init = arp_tables_net_init,
1632	.exit = arp_tables_net_exit,
1633};
1634
1635static int __init arp_tables_init(void)
1636{
1637	int ret;
1638
1639	ret = register_pernet_subsys(&arp_tables_net_ops);
1640	if (ret < 0)
1641		goto err1;
1642
1643	/* No one else will be downing sem now, so we won't sleep */
1644	ret = xt_register_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1645	if (ret < 0)
1646		goto err2;
1647
1648	/* Register setsockopt */
1649	ret = nf_register_sockopt(&arpt_sockopts);
1650	if (ret < 0)
1651		goto err4;
1652
1653	return 0;
1654
1655err4:
1656	xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1657err2:
1658	unregister_pernet_subsys(&arp_tables_net_ops);
1659err1:
1660	return ret;
1661}
1662
1663static void __exit arp_tables_fini(void)
1664{
1665	nf_unregister_sockopt(&arpt_sockopts);
1666	xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
1667	unregister_pernet_subsys(&arp_tables_net_ops);
1668}
1669
1670EXPORT_SYMBOL(arpt_register_table);
1671EXPORT_SYMBOL(arpt_unregister_table);
1672EXPORT_SYMBOL(arpt_do_table);
1673
1674module_init(arp_tables_init);
1675module_exit(arp_tables_fini);