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/net/ipv4/arp.c

http://github.com/mirrors/linux
C | 1451 lines | 1019 code | 177 blank | 255 comment | 223 complexity | 8f44b95e811ddd2fc427f8698e59d19d MD5 | raw file
   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/* linux/net/ipv4/arp.c
   3 *
   4 * Copyright (C) 1994 by Florian  La Roche
   5 *
   6 * This module implements the Address Resolution Protocol ARP (RFC 826),
   7 * which is used to convert IP addresses (or in the future maybe other
   8 * high-level addresses) into a low-level hardware address (like an Ethernet
   9 * address).
  10 *
  11 * Fixes:
  12 *		Alan Cox	:	Removed the Ethernet assumptions in
  13 *					Florian's code
  14 *		Alan Cox	:	Fixed some small errors in the ARP
  15 *					logic
  16 *		Alan Cox	:	Allow >4K in /proc
  17 *		Alan Cox	:	Make ARP add its own protocol entry
  18 *		Ross Martin     :       Rewrote arp_rcv() and arp_get_info()
  19 *		Stephen Henson	:	Add AX25 support to arp_get_info()
  20 *		Alan Cox	:	Drop data when a device is downed.
  21 *		Alan Cox	:	Use init_timer().
  22 *		Alan Cox	:	Double lock fixes.
  23 *		Martin Seine	:	Move the arphdr structure
  24 *					to if_arp.h for compatibility.
  25 *					with BSD based programs.
  26 *		Andrew Tridgell :       Added ARP netmask code and
  27 *					re-arranged proxy handling.
  28 *		Alan Cox	:	Changed to use notifiers.
  29 *		Niibe Yutaka	:	Reply for this device or proxies only.
  30 *		Alan Cox	:	Don't proxy across hardware types!
  31 *		Jonathan Naylor :	Added support for NET/ROM.
  32 *		Mike Shaver     :       RFC1122 checks.
  33 *		Jonathan Naylor :	Only lookup the hardware address for
  34 *					the correct hardware type.
  35 *		Germano Caronni	:	Assorted subtle races.
  36 *		Craig Schlenter :	Don't modify permanent entry
  37 *					during arp_rcv.
  38 *		Russ Nelson	:	Tidied up a few bits.
  39 *		Alexey Kuznetsov:	Major changes to caching and behaviour,
  40 *					eg intelligent arp probing and
  41 *					generation
  42 *					of host down events.
  43 *		Alan Cox	:	Missing unlock in device events.
  44 *		Eckes		:	ARP ioctl control errors.
  45 *		Alexey Kuznetsov:	Arp free fix.
  46 *		Manuel Rodriguez:	Gratuitous ARP.
  47 *              Jonathan Layes  :       Added arpd support through kerneld
  48 *                                      message queue (960314)
  49 *		Mike Shaver	:	/proc/sys/net/ipv4/arp_* support
  50 *		Mike McLagan    :	Routing by source
  51 *		Stuart Cheshire	:	Metricom and grat arp fixes
  52 *					*** FOR 2.1 clean this up ***
  53 *		Lawrence V. Stefani: (08/12/96) Added FDDI support.
  54 *		Alan Cox	:	Took the AP1000 nasty FDDI hack and
  55 *					folded into the mainstream FDDI code.
  56 *					Ack spit, Linus how did you allow that
  57 *					one in...
  58 *		Jes Sorensen	:	Make FDDI work again in 2.1.x and
  59 *					clean up the APFDDI & gen. FDDI bits.
  60 *		Alexey Kuznetsov:	new arp state machine;
  61 *					now it is in net/core/neighbour.c.
  62 *		Krzysztof Halasa:	Added Frame Relay ARP support.
  63 *		Arnaldo C. Melo :	convert /proc/net/arp to seq_file
  64 *		Shmulik Hen:		Split arp_send to arp_create and
  65 *					arp_xmit so intermediate drivers like
  66 *					bonding can change the skb before
  67 *					sending (e.g. insert 8021q tag).
  68 *		Harald Welte	:	convert to make use of jenkins hash
  69 *		Jesper D. Brouer:       Proxy ARP PVLAN RFC 3069 support.
  70 */
  71
  72#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  73
  74#include <linux/module.h>
  75#include <linux/types.h>
  76#include <linux/string.h>
  77#include <linux/kernel.h>
  78#include <linux/capability.h>
  79#include <linux/socket.h>
  80#include <linux/sockios.h>
  81#include <linux/errno.h>
  82#include <linux/in.h>
  83#include <linux/mm.h>
  84#include <linux/inet.h>
  85#include <linux/inetdevice.h>
  86#include <linux/netdevice.h>
  87#include <linux/etherdevice.h>
  88#include <linux/fddidevice.h>
  89#include <linux/if_arp.h>
  90#include <linux/skbuff.h>
  91#include <linux/proc_fs.h>
  92#include <linux/seq_file.h>
  93#include <linux/stat.h>
  94#include <linux/init.h>
  95#include <linux/net.h>
  96#include <linux/rcupdate.h>
  97#include <linux/slab.h>
  98#ifdef CONFIG_SYSCTL
  99#include <linux/sysctl.h>
 100#endif
 101
 102#include <net/net_namespace.h>
 103#include <net/ip.h>
 104#include <net/icmp.h>
 105#include <net/route.h>
 106#include <net/protocol.h>
 107#include <net/tcp.h>
 108#include <net/sock.h>
 109#include <net/arp.h>
 110#include <net/ax25.h>
 111#include <net/netrom.h>
 112#include <net/dst_metadata.h>
 113#include <net/ip_tunnels.h>
 114
 115#include <linux/uaccess.h>
 116
 117#include <linux/netfilter_arp.h>
 118
 119/*
 120 *	Interface to generic neighbour cache.
 121 */
 122static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd);
 123static bool arp_key_eq(const struct neighbour *n, const void *pkey);
 124static int arp_constructor(struct neighbour *neigh);
 125static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
 126static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
 127static void parp_redo(struct sk_buff *skb);
 128
 129static const struct neigh_ops arp_generic_ops = {
 130	.family =		AF_INET,
 131	.solicit =		arp_solicit,
 132	.error_report =		arp_error_report,
 133	.output =		neigh_resolve_output,
 134	.connected_output =	neigh_connected_output,
 135};
 136
 137static const struct neigh_ops arp_hh_ops = {
 138	.family =		AF_INET,
 139	.solicit =		arp_solicit,
 140	.error_report =		arp_error_report,
 141	.output =		neigh_resolve_output,
 142	.connected_output =	neigh_resolve_output,
 143};
 144
 145static const struct neigh_ops arp_direct_ops = {
 146	.family =		AF_INET,
 147	.output =		neigh_direct_output,
 148	.connected_output =	neigh_direct_output,
 149};
 150
 151struct neigh_table arp_tbl = {
 152	.family		= AF_INET,
 153	.key_len	= 4,
 154	.protocol	= cpu_to_be16(ETH_P_IP),
 155	.hash		= arp_hash,
 156	.key_eq		= arp_key_eq,
 157	.constructor	= arp_constructor,
 158	.proxy_redo	= parp_redo,
 159	.id		= "arp_cache",
 160	.parms		= {
 161		.tbl			= &arp_tbl,
 162		.reachable_time		= 30 * HZ,
 163		.data	= {
 164			[NEIGH_VAR_MCAST_PROBES] = 3,
 165			[NEIGH_VAR_UCAST_PROBES] = 3,
 166			[NEIGH_VAR_RETRANS_TIME] = 1 * HZ,
 167			[NEIGH_VAR_BASE_REACHABLE_TIME] = 30 * HZ,
 168			[NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ,
 169			[NEIGH_VAR_GC_STALETIME] = 60 * HZ,
 170			[NEIGH_VAR_QUEUE_LEN_BYTES] = SK_WMEM_MAX,
 171			[NEIGH_VAR_PROXY_QLEN] = 64,
 172			[NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ,
 173			[NEIGH_VAR_PROXY_DELAY]	= (8 * HZ) / 10,
 174			[NEIGH_VAR_LOCKTIME] = 1 * HZ,
 175		},
 176	},
 177	.gc_interval	= 30 * HZ,
 178	.gc_thresh1	= 128,
 179	.gc_thresh2	= 512,
 180	.gc_thresh3	= 1024,
 181};
 182EXPORT_SYMBOL(arp_tbl);
 183
 184int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir)
 185{
 186	switch (dev->type) {
 187	case ARPHRD_ETHER:
 188	case ARPHRD_FDDI:
 189	case ARPHRD_IEEE802:
 190		ip_eth_mc_map(addr, haddr);
 191		return 0;
 192	case ARPHRD_INFINIBAND:
 193		ip_ib_mc_map(addr, dev->broadcast, haddr);
 194		return 0;
 195	case ARPHRD_IPGRE:
 196		ip_ipgre_mc_map(addr, dev->broadcast, haddr);
 197		return 0;
 198	default:
 199		if (dir) {
 200			memcpy(haddr, dev->broadcast, dev->addr_len);
 201			return 0;
 202		}
 203	}
 204	return -EINVAL;
 205}
 206
 207
 208static u32 arp_hash(const void *pkey,
 209		    const struct net_device *dev,
 210		    __u32 *hash_rnd)
 211{
 212	return arp_hashfn(pkey, dev, hash_rnd);
 213}
 214
 215static bool arp_key_eq(const struct neighbour *neigh, const void *pkey)
 216{
 217	return neigh_key_eq32(neigh, pkey);
 218}
 219
 220static int arp_constructor(struct neighbour *neigh)
 221{
 222	__be32 addr;
 223	struct net_device *dev = neigh->dev;
 224	struct in_device *in_dev;
 225	struct neigh_parms *parms;
 226	u32 inaddr_any = INADDR_ANY;
 227
 228	if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT))
 229		memcpy(neigh->primary_key, &inaddr_any, arp_tbl.key_len);
 230
 231	addr = *(__be32 *)neigh->primary_key;
 232	rcu_read_lock();
 233	in_dev = __in_dev_get_rcu(dev);
 234	if (!in_dev) {
 235		rcu_read_unlock();
 236		return -EINVAL;
 237	}
 238
 239	neigh->type = inet_addr_type_dev_table(dev_net(dev), dev, addr);
 240
 241	parms = in_dev->arp_parms;
 242	__neigh_parms_put(neigh->parms);
 243	neigh->parms = neigh_parms_clone(parms);
 244	rcu_read_unlock();
 245
 246	if (!dev->header_ops) {
 247		neigh->nud_state = NUD_NOARP;
 248		neigh->ops = &arp_direct_ops;
 249		neigh->output = neigh_direct_output;
 250	} else {
 251		/* Good devices (checked by reading texts, but only Ethernet is
 252		   tested)
 253
 254		   ARPHRD_ETHER: (ethernet, apfddi)
 255		   ARPHRD_FDDI: (fddi)
 256		   ARPHRD_IEEE802: (tr)
 257		   ARPHRD_METRICOM: (strip)
 258		   ARPHRD_ARCNET:
 259		   etc. etc. etc.
 260
 261		   ARPHRD_IPDDP will also work, if author repairs it.
 262		   I did not it, because this driver does not work even
 263		   in old paradigm.
 264		 */
 265
 266		if (neigh->type == RTN_MULTICAST) {
 267			neigh->nud_state = NUD_NOARP;
 268			arp_mc_map(addr, neigh->ha, dev, 1);
 269		} else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) {
 270			neigh->nud_state = NUD_NOARP;
 271			memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
 272		} else if (neigh->type == RTN_BROADCAST ||
 273			   (dev->flags & IFF_POINTOPOINT)) {
 274			neigh->nud_state = NUD_NOARP;
 275			memcpy(neigh->ha, dev->broadcast, dev->addr_len);
 276		}
 277
 278		if (dev->header_ops->cache)
 279			neigh->ops = &arp_hh_ops;
 280		else
 281			neigh->ops = &arp_generic_ops;
 282
 283		if (neigh->nud_state & NUD_VALID)
 284			neigh->output = neigh->ops->connected_output;
 285		else
 286			neigh->output = neigh->ops->output;
 287	}
 288	return 0;
 289}
 290
 291static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
 292{
 293	dst_link_failure(skb);
 294	kfree_skb(skb);
 295}
 296
 297/* Create and send an arp packet. */
 298static void arp_send_dst(int type, int ptype, __be32 dest_ip,
 299			 struct net_device *dev, __be32 src_ip,
 300			 const unsigned char *dest_hw,
 301			 const unsigned char *src_hw,
 302			 const unsigned char *target_hw,
 303			 struct dst_entry *dst)
 304{
 305	struct sk_buff *skb;
 306
 307	/* arp on this interface. */
 308	if (dev->flags & IFF_NOARP)
 309		return;
 310
 311	skb = arp_create(type, ptype, dest_ip, dev, src_ip,
 312			 dest_hw, src_hw, target_hw);
 313	if (!skb)
 314		return;
 315
 316	skb_dst_set(skb, dst_clone(dst));
 317	arp_xmit(skb);
 318}
 319
 320void arp_send(int type, int ptype, __be32 dest_ip,
 321	      struct net_device *dev, __be32 src_ip,
 322	      const unsigned char *dest_hw, const unsigned char *src_hw,
 323	      const unsigned char *target_hw)
 324{
 325	arp_send_dst(type, ptype, dest_ip, dev, src_ip, dest_hw, src_hw,
 326		     target_hw, NULL);
 327}
 328EXPORT_SYMBOL(arp_send);
 329
 330static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
 331{
 332	__be32 saddr = 0;
 333	u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL;
 334	struct net_device *dev = neigh->dev;
 335	__be32 target = *(__be32 *)neigh->primary_key;
 336	int probes = atomic_read(&neigh->probes);
 337	struct in_device *in_dev;
 338	struct dst_entry *dst = NULL;
 339
 340	rcu_read_lock();
 341	in_dev = __in_dev_get_rcu(dev);
 342	if (!in_dev) {
 343		rcu_read_unlock();
 344		return;
 345	}
 346	switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
 347	default:
 348	case 0:		/* By default announce any local IP */
 349		if (skb && inet_addr_type_dev_table(dev_net(dev), dev,
 350					  ip_hdr(skb)->saddr) == RTN_LOCAL)
 351			saddr = ip_hdr(skb)->saddr;
 352		break;
 353	case 1:		/* Restrict announcements of saddr in same subnet */
 354		if (!skb)
 355			break;
 356		saddr = ip_hdr(skb)->saddr;
 357		if (inet_addr_type_dev_table(dev_net(dev), dev,
 358					     saddr) == RTN_LOCAL) {
 359			/* saddr should be known to target */
 360			if (inet_addr_onlink(in_dev, target, saddr))
 361				break;
 362		}
 363		saddr = 0;
 364		break;
 365	case 2:		/* Avoid secondary IPs, get a primary/preferred one */
 366		break;
 367	}
 368	rcu_read_unlock();
 369
 370	if (!saddr)
 371		saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
 372
 373	probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES);
 374	if (probes < 0) {
 375		if (!(neigh->nud_state & NUD_VALID))
 376			pr_debug("trying to ucast probe in NUD_INVALID\n");
 377		neigh_ha_snapshot(dst_ha, neigh, dev);
 378		dst_hw = dst_ha;
 379	} else {
 380		probes -= NEIGH_VAR(neigh->parms, APP_PROBES);
 381		if (probes < 0) {
 382			neigh_app_ns(neigh);
 383			return;
 384		}
 385	}
 386
 387	if (skb && !(dev->priv_flags & IFF_XMIT_DST_RELEASE))
 388		dst = skb_dst(skb);
 389	arp_send_dst(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
 390		     dst_hw, dev->dev_addr, NULL, dst);
 391}
 392
 393static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip)
 394{
 395	struct net *net = dev_net(in_dev->dev);
 396	int scope;
 397
 398	switch (IN_DEV_ARP_IGNORE(in_dev)) {
 399	case 0:	/* Reply, the tip is already validated */
 400		return 0;
 401	case 1:	/* Reply only if tip is configured on the incoming interface */
 402		sip = 0;
 403		scope = RT_SCOPE_HOST;
 404		break;
 405	case 2:	/*
 406		 * Reply only if tip is configured on the incoming interface
 407		 * and is in same subnet as sip
 408		 */
 409		scope = RT_SCOPE_HOST;
 410		break;
 411	case 3:	/* Do not reply for scope host addresses */
 412		sip = 0;
 413		scope = RT_SCOPE_LINK;
 414		in_dev = NULL;
 415		break;
 416	case 4:	/* Reserved */
 417	case 5:
 418	case 6:
 419	case 7:
 420		return 0;
 421	case 8:	/* Do not reply */
 422		return 1;
 423	default:
 424		return 0;
 425	}
 426	return !inet_confirm_addr(net, in_dev, sip, tip, scope);
 427}
 428
 429static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
 430{
 431	struct rtable *rt;
 432	int flag = 0;
 433	/*unsigned long now; */
 434	struct net *net = dev_net(dev);
 435
 436	rt = ip_route_output(net, sip, tip, 0, l3mdev_master_ifindex_rcu(dev));
 437	if (IS_ERR(rt))
 438		return 1;
 439	if (rt->dst.dev != dev) {
 440		__NET_INC_STATS(net, LINUX_MIB_ARPFILTER);
 441		flag = 1;
 442	}
 443	ip_rt_put(rt);
 444	return flag;
 445}
 446
 447/*
 448 * Check if we can use proxy ARP for this path
 449 */
 450static inline int arp_fwd_proxy(struct in_device *in_dev,
 451				struct net_device *dev,	struct rtable *rt)
 452{
 453	struct in_device *out_dev;
 454	int imi, omi = -1;
 455
 456	if (rt->dst.dev == dev)
 457		return 0;
 458
 459	if (!IN_DEV_PROXY_ARP(in_dev))
 460		return 0;
 461	imi = IN_DEV_MEDIUM_ID(in_dev);
 462	if (imi == 0)
 463		return 1;
 464	if (imi == -1)
 465		return 0;
 466
 467	/* place to check for proxy_arp for routes */
 468
 469	out_dev = __in_dev_get_rcu(rt->dst.dev);
 470	if (out_dev)
 471		omi = IN_DEV_MEDIUM_ID(out_dev);
 472
 473	return omi != imi && omi != -1;
 474}
 475
 476/*
 477 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
 478 *
 479 * RFC3069 supports proxy arp replies back to the same interface.  This
 480 * is done to support (ethernet) switch features, like RFC 3069, where
 481 * the individual ports are not allowed to communicate with each
 482 * other, BUT they are allowed to talk to the upstream router.  As
 483 * described in RFC 3069, it is possible to allow these hosts to
 484 * communicate through the upstream router, by proxy_arp'ing.
 485 *
 486 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
 487 *
 488 *  This technology is known by different names:
 489 *    In RFC 3069 it is called VLAN Aggregation.
 490 *    Cisco and Allied Telesyn call it Private VLAN.
 491 *    Hewlett-Packard call it Source-Port filtering or port-isolation.
 492 *    Ericsson call it MAC-Forced Forwarding (RFC Draft).
 493 *
 494 */
 495static inline int arp_fwd_pvlan(struct in_device *in_dev,
 496				struct net_device *dev,	struct rtable *rt,
 497				__be32 sip, __be32 tip)
 498{
 499	/* Private VLAN is only concerned about the same ethernet segment */
 500	if (rt->dst.dev != dev)
 501		return 0;
 502
 503	/* Don't reply on self probes (often done by windowz boxes)*/
 504	if (sip == tip)
 505		return 0;
 506
 507	if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
 508		return 1;
 509	else
 510		return 0;
 511}
 512
 513/*
 514 *	Interface to link layer: send routine and receive handler.
 515 */
 516
 517/*
 518 *	Create an arp packet. If dest_hw is not set, we create a broadcast
 519 *	message.
 520 */
 521struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
 522			   struct net_device *dev, __be32 src_ip,
 523			   const unsigned char *dest_hw,
 524			   const unsigned char *src_hw,
 525			   const unsigned char *target_hw)
 526{
 527	struct sk_buff *skb;
 528	struct arphdr *arp;
 529	unsigned char *arp_ptr;
 530	int hlen = LL_RESERVED_SPACE(dev);
 531	int tlen = dev->needed_tailroom;
 532
 533	/*
 534	 *	Allocate a buffer
 535	 */
 536
 537	skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
 538	if (!skb)
 539		return NULL;
 540
 541	skb_reserve(skb, hlen);
 542	skb_reset_network_header(skb);
 543	arp = skb_put(skb, arp_hdr_len(dev));
 544	skb->dev = dev;
 545	skb->protocol = htons(ETH_P_ARP);
 546	if (!src_hw)
 547		src_hw = dev->dev_addr;
 548	if (!dest_hw)
 549		dest_hw = dev->broadcast;
 550
 551	/*
 552	 *	Fill the device header for the ARP frame
 553	 */
 554	if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
 555		goto out;
 556
 557	/*
 558	 * Fill out the arp protocol part.
 559	 *
 560	 * The arp hardware type should match the device type, except for FDDI,
 561	 * which (according to RFC 1390) should always equal 1 (Ethernet).
 562	 */
 563	/*
 564	 *	Exceptions everywhere. AX.25 uses the AX.25 PID value not the
 565	 *	DIX code for the protocol. Make these device structure fields.
 566	 */
 567	switch (dev->type) {
 568	default:
 569		arp->ar_hrd = htons(dev->type);
 570		arp->ar_pro = htons(ETH_P_IP);
 571		break;
 572
 573#if IS_ENABLED(CONFIG_AX25)
 574	case ARPHRD_AX25:
 575		arp->ar_hrd = htons(ARPHRD_AX25);
 576		arp->ar_pro = htons(AX25_P_IP);
 577		break;
 578
 579#if IS_ENABLED(CONFIG_NETROM)
 580	case ARPHRD_NETROM:
 581		arp->ar_hrd = htons(ARPHRD_NETROM);
 582		arp->ar_pro = htons(AX25_P_IP);
 583		break;
 584#endif
 585#endif
 586
 587#if IS_ENABLED(CONFIG_FDDI)
 588	case ARPHRD_FDDI:
 589		arp->ar_hrd = htons(ARPHRD_ETHER);
 590		arp->ar_pro = htons(ETH_P_IP);
 591		break;
 592#endif
 593	}
 594
 595	arp->ar_hln = dev->addr_len;
 596	arp->ar_pln = 4;
 597	arp->ar_op = htons(type);
 598
 599	arp_ptr = (unsigned char *)(arp + 1);
 600
 601	memcpy(arp_ptr, src_hw, dev->addr_len);
 602	arp_ptr += dev->addr_len;
 603	memcpy(arp_ptr, &src_ip, 4);
 604	arp_ptr += 4;
 605
 606	switch (dev->type) {
 607#if IS_ENABLED(CONFIG_FIREWIRE_NET)
 608	case ARPHRD_IEEE1394:
 609		break;
 610#endif
 611	default:
 612		if (target_hw)
 613			memcpy(arp_ptr, target_hw, dev->addr_len);
 614		else
 615			memset(arp_ptr, 0, dev->addr_len);
 616		arp_ptr += dev->addr_len;
 617	}
 618	memcpy(arp_ptr, &dest_ip, 4);
 619
 620	return skb;
 621
 622out:
 623	kfree_skb(skb);
 624	return NULL;
 625}
 626EXPORT_SYMBOL(arp_create);
 627
 628static int arp_xmit_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 629{
 630	return dev_queue_xmit(skb);
 631}
 632
 633/*
 634 *	Send an arp packet.
 635 */
 636void arp_xmit(struct sk_buff *skb)
 637{
 638	/* Send it off, maybe filter it using firewalling first.  */
 639	NF_HOOK(NFPROTO_ARP, NF_ARP_OUT,
 640		dev_net(skb->dev), NULL, skb, NULL, skb->dev,
 641		arp_xmit_finish);
 642}
 643EXPORT_SYMBOL(arp_xmit);
 644
 645static bool arp_is_garp(struct net *net, struct net_device *dev,
 646			int *addr_type, __be16 ar_op,
 647			__be32 sip, __be32 tip,
 648			unsigned char *sha, unsigned char *tha)
 649{
 650	bool is_garp = tip == sip;
 651
 652	/* Gratuitous ARP _replies_ also require target hwaddr to be
 653	 * the same as source.
 654	 */
 655	if (is_garp && ar_op == htons(ARPOP_REPLY))
 656		is_garp =
 657			/* IPv4 over IEEE 1394 doesn't provide target
 658			 * hardware address field in its ARP payload.
 659			 */
 660			tha &&
 661			!memcmp(tha, sha, dev->addr_len);
 662
 663	if (is_garp) {
 664		*addr_type = inet_addr_type_dev_table(net, dev, sip);
 665		if (*addr_type != RTN_UNICAST)
 666			is_garp = false;
 667	}
 668	return is_garp;
 669}
 670
 671/*
 672 *	Process an arp request.
 673 */
 674
 675static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb)
 676{
 677	struct net_device *dev = skb->dev;
 678	struct in_device *in_dev = __in_dev_get_rcu(dev);
 679	struct arphdr *arp;
 680	unsigned char *arp_ptr;
 681	struct rtable *rt;
 682	unsigned char *sha;
 683	unsigned char *tha = NULL;
 684	__be32 sip, tip;
 685	u16 dev_type = dev->type;
 686	int addr_type;
 687	struct neighbour *n;
 688	struct dst_entry *reply_dst = NULL;
 689	bool is_garp = false;
 690
 691	/* arp_rcv below verifies the ARP header and verifies the device
 692	 * is ARP'able.
 693	 */
 694
 695	if (!in_dev)
 696		goto out_free_skb;
 697
 698	arp = arp_hdr(skb);
 699
 700	switch (dev_type) {
 701	default:
 702		if (arp->ar_pro != htons(ETH_P_IP) ||
 703		    htons(dev_type) != arp->ar_hrd)
 704			goto out_free_skb;
 705		break;
 706	case ARPHRD_ETHER:
 707	case ARPHRD_FDDI:
 708	case ARPHRD_IEEE802:
 709		/*
 710		 * ETHERNET, and Fibre Channel (which are IEEE 802
 711		 * devices, according to RFC 2625) devices will accept ARP
 712		 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
 713		 * This is the case also of FDDI, where the RFC 1390 says that
 714		 * FDDI devices should accept ARP hardware of (1) Ethernet,
 715		 * however, to be more robust, we'll accept both 1 (Ethernet)
 716		 * or 6 (IEEE 802.2)
 717		 */
 718		if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
 719		     arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
 720		    arp->ar_pro != htons(ETH_P_IP))
 721			goto out_free_skb;
 722		break;
 723	case ARPHRD_AX25:
 724		if (arp->ar_pro != htons(AX25_P_IP) ||
 725		    arp->ar_hrd != htons(ARPHRD_AX25))
 726			goto out_free_skb;
 727		break;
 728	case ARPHRD_NETROM:
 729		if (arp->ar_pro != htons(AX25_P_IP) ||
 730		    arp->ar_hrd != htons(ARPHRD_NETROM))
 731			goto out_free_skb;
 732		break;
 733	}
 734
 735	/* Understand only these message types */
 736
 737	if (arp->ar_op != htons(ARPOP_REPLY) &&
 738	    arp->ar_op != htons(ARPOP_REQUEST))
 739		goto out_free_skb;
 740
 741/*
 742 *	Extract fields
 743 */
 744	arp_ptr = (unsigned char *)(arp + 1);
 745	sha	= arp_ptr;
 746	arp_ptr += dev->addr_len;
 747	memcpy(&sip, arp_ptr, 4);
 748	arp_ptr += 4;
 749	switch (dev_type) {
 750#if IS_ENABLED(CONFIG_FIREWIRE_NET)
 751	case ARPHRD_IEEE1394:
 752		break;
 753#endif
 754	default:
 755		tha = arp_ptr;
 756		arp_ptr += dev->addr_len;
 757	}
 758	memcpy(&tip, arp_ptr, 4);
 759/*
 760 *	Check for bad requests for 127.x.x.x and requests for multicast
 761 *	addresses.  If this is one such, delete it.
 762 */
 763	if (ipv4_is_multicast(tip) ||
 764	    (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip)))
 765		goto out_free_skb;
 766
 767 /*
 768  *	For some 802.11 wireless deployments (and possibly other networks),
 769  *	there will be an ARP proxy and gratuitous ARP frames are attacks
 770  *	and thus should not be accepted.
 771  */
 772	if (sip == tip && IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP))
 773		goto out_free_skb;
 774
 775/*
 776 *     Special case: We must set Frame Relay source Q.922 address
 777 */
 778	if (dev_type == ARPHRD_DLCI)
 779		sha = dev->broadcast;
 780
 781/*
 782 *  Process entry.  The idea here is we want to send a reply if it is a
 783 *  request for us or if it is a request for someone else that we hold
 784 *  a proxy for.  We want to add an entry to our cache if it is a reply
 785 *  to us or if it is a request for our address.
 786 *  (The assumption for this last is that if someone is requesting our
 787 *  address, they are probably intending to talk to us, so it saves time
 788 *  if we cache their address.  Their address is also probably not in
 789 *  our cache, since ours is not in their cache.)
 790 *
 791 *  Putting this another way, we only care about replies if they are to
 792 *  us, in which case we add them to the cache.  For requests, we care
 793 *  about those for us and those for our proxies.  We reply to both,
 794 *  and in the case of requests for us we add the requester to the arp
 795 *  cache.
 796 */
 797
 798	if (arp->ar_op == htons(ARPOP_REQUEST) && skb_metadata_dst(skb))
 799		reply_dst = (struct dst_entry *)
 800			    iptunnel_metadata_reply(skb_metadata_dst(skb),
 801						    GFP_ATOMIC);
 802
 803	/* Special case: IPv4 duplicate address detection packet (RFC2131) */
 804	if (sip == 0) {
 805		if (arp->ar_op == htons(ARPOP_REQUEST) &&
 806		    inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL &&
 807		    !arp_ignore(in_dev, sip, tip))
 808			arp_send_dst(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip,
 809				     sha, dev->dev_addr, sha, reply_dst);
 810		goto out_consume_skb;
 811	}
 812
 813	if (arp->ar_op == htons(ARPOP_REQUEST) &&
 814	    ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
 815
 816		rt = skb_rtable(skb);
 817		addr_type = rt->rt_type;
 818
 819		if (addr_type == RTN_LOCAL) {
 820			int dont_send;
 821
 822			dont_send = arp_ignore(in_dev, sip, tip);
 823			if (!dont_send && IN_DEV_ARPFILTER(in_dev))
 824				dont_send = arp_filter(sip, tip, dev);
 825			if (!dont_send) {
 826				n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
 827				if (n) {
 828					arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
 829						     sip, dev, tip, sha,
 830						     dev->dev_addr, sha,
 831						     reply_dst);
 832					neigh_release(n);
 833				}
 834			}
 835			goto out_consume_skb;
 836		} else if (IN_DEV_FORWARD(in_dev)) {
 837			if (addr_type == RTN_UNICAST  &&
 838			    (arp_fwd_proxy(in_dev, dev, rt) ||
 839			     arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
 840			     (rt->dst.dev != dev &&
 841			      pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
 842				n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
 843				if (n)
 844					neigh_release(n);
 845
 846				if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
 847				    skb->pkt_type == PACKET_HOST ||
 848				    NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) {
 849					arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
 850						     sip, dev, tip, sha,
 851						     dev->dev_addr, sha,
 852						     reply_dst);
 853				} else {
 854					pneigh_enqueue(&arp_tbl,
 855						       in_dev->arp_parms, skb);
 856					goto out_free_dst;
 857				}
 858				goto out_consume_skb;
 859			}
 860		}
 861	}
 862
 863	/* Update our ARP tables */
 864
 865	n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
 866
 867	addr_type = -1;
 868	if (n || IN_DEV_ARP_ACCEPT(in_dev)) {
 869		is_garp = arp_is_garp(net, dev, &addr_type, arp->ar_op,
 870				      sip, tip, sha, tha);
 871	}
 872
 873	if (IN_DEV_ARP_ACCEPT(in_dev)) {
 874		/* Unsolicited ARP is not accepted by default.
 875		   It is possible, that this option should be enabled for some
 876		   devices (strip is candidate)
 877		 */
 878		if (!n &&
 879		    (is_garp ||
 880		     (arp->ar_op == htons(ARPOP_REPLY) &&
 881		      (addr_type == RTN_UNICAST ||
 882		       (addr_type < 0 &&
 883			/* postpone calculation to as late as possible */
 884			inet_addr_type_dev_table(net, dev, sip) ==
 885				RTN_UNICAST)))))
 886			n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
 887	}
 888
 889	if (n) {
 890		int state = NUD_REACHABLE;
 891		int override;
 892
 893		/* If several different ARP replies follows back-to-back,
 894		   use the FIRST one. It is possible, if several proxy
 895		   agents are active. Taking the first reply prevents
 896		   arp trashing and chooses the fastest router.
 897		 */
 898		override = time_after(jiffies,
 899				      n->updated +
 900				      NEIGH_VAR(n->parms, LOCKTIME)) ||
 901			   is_garp;
 902
 903		/* Broadcast replies and request packets
 904		   do not assert neighbour reachability.
 905		 */
 906		if (arp->ar_op != htons(ARPOP_REPLY) ||
 907		    skb->pkt_type != PACKET_HOST)
 908			state = NUD_STALE;
 909		neigh_update(n, sha, state,
 910			     override ? NEIGH_UPDATE_F_OVERRIDE : 0, 0);
 911		neigh_release(n);
 912	}
 913
 914out_consume_skb:
 915	consume_skb(skb);
 916
 917out_free_dst:
 918	dst_release(reply_dst);
 919	return NET_RX_SUCCESS;
 920
 921out_free_skb:
 922	kfree_skb(skb);
 923	return NET_RX_DROP;
 924}
 925
 926static void parp_redo(struct sk_buff *skb)
 927{
 928	arp_process(dev_net(skb->dev), NULL, skb);
 929}
 930
 931
 932/*
 933 *	Receive an arp request from the device layer.
 934 */
 935
 936static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
 937		   struct packet_type *pt, struct net_device *orig_dev)
 938{
 939	const struct arphdr *arp;
 940
 941	/* do not tweak dropwatch on an ARP we will ignore */
 942	if (dev->flags & IFF_NOARP ||
 943	    skb->pkt_type == PACKET_OTHERHOST ||
 944	    skb->pkt_type == PACKET_LOOPBACK)
 945		goto consumeskb;
 946
 947	skb = skb_share_check(skb, GFP_ATOMIC);
 948	if (!skb)
 949		goto out_of_mem;
 950
 951	/* ARP header, plus 2 device addresses, plus 2 IP addresses.  */
 952	if (!pskb_may_pull(skb, arp_hdr_len(dev)))
 953		goto freeskb;
 954
 955	arp = arp_hdr(skb);
 956	if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4)
 957		goto freeskb;
 958
 959	memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
 960
 961	return NF_HOOK(NFPROTO_ARP, NF_ARP_IN,
 962		       dev_net(dev), NULL, skb, dev, NULL,
 963		       arp_process);
 964
 965consumeskb:
 966	consume_skb(skb);
 967	return NET_RX_SUCCESS;
 968freeskb:
 969	kfree_skb(skb);
 970out_of_mem:
 971	return NET_RX_DROP;
 972}
 973
 974/*
 975 *	User level interface (ioctl)
 976 */
 977
 978/*
 979 *	Set (create) an ARP cache entry.
 980 */
 981
 982static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
 983{
 984	if (!dev) {
 985		IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
 986		return 0;
 987	}
 988	if (__in_dev_get_rtnl(dev)) {
 989		IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
 990		return 0;
 991	}
 992	return -ENXIO;
 993}
 994
 995static int arp_req_set_public(struct net *net, struct arpreq *r,
 996		struct net_device *dev)
 997{
 998	__be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
 999	__be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1000
1001	if (mask && mask != htonl(0xFFFFFFFF))
1002		return -EINVAL;
1003	if (!dev && (r->arp_flags & ATF_COM)) {
1004		dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family,
1005				      r->arp_ha.sa_data);
1006		if (!dev)
1007			return -ENODEV;
1008	}
1009	if (mask) {
1010		if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1))
1011			return -ENOBUFS;
1012		return 0;
1013	}
1014
1015	return arp_req_set_proxy(net, dev, 1);
1016}
1017
1018static int arp_req_set(struct net *net, struct arpreq *r,
1019		       struct net_device *dev)
1020{
1021	__be32 ip;
1022	struct neighbour *neigh;
1023	int err;
1024
1025	if (r->arp_flags & ATF_PUBL)
1026		return arp_req_set_public(net, r, dev);
1027
1028	ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1029	if (r->arp_flags & ATF_PERM)
1030		r->arp_flags |= ATF_COM;
1031	if (!dev) {
1032		struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1033
1034		if (IS_ERR(rt))
1035			return PTR_ERR(rt);
1036		dev = rt->dst.dev;
1037		ip_rt_put(rt);
1038		if (!dev)
1039			return -EINVAL;
1040	}
1041	switch (dev->type) {
1042#if IS_ENABLED(CONFIG_FDDI)
1043	case ARPHRD_FDDI:
1044		/*
1045		 * According to RFC 1390, FDDI devices should accept ARP
1046		 * hardware types of 1 (Ethernet).  However, to be more
1047		 * robust, we'll accept hardware types of either 1 (Ethernet)
1048		 * or 6 (IEEE 802.2).
1049		 */
1050		if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1051		    r->arp_ha.sa_family != ARPHRD_ETHER &&
1052		    r->arp_ha.sa_family != ARPHRD_IEEE802)
1053			return -EINVAL;
1054		break;
1055#endif
1056	default:
1057		if (r->arp_ha.sa_family != dev->type)
1058			return -EINVAL;
1059		break;
1060	}
1061
1062	neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1063	err = PTR_ERR(neigh);
1064	if (!IS_ERR(neigh)) {
1065		unsigned int state = NUD_STALE;
1066		if (r->arp_flags & ATF_PERM)
1067			state = NUD_PERMANENT;
1068		err = neigh_update(neigh, (r->arp_flags & ATF_COM) ?
1069				   r->arp_ha.sa_data : NULL, state,
1070				   NEIGH_UPDATE_F_OVERRIDE |
1071				   NEIGH_UPDATE_F_ADMIN, 0);
1072		neigh_release(neigh);
1073	}
1074	return err;
1075}
1076
1077static unsigned int arp_state_to_flags(struct neighbour *neigh)
1078{
1079	if (neigh->nud_state&NUD_PERMANENT)
1080		return ATF_PERM | ATF_COM;
1081	else if (neigh->nud_state&NUD_VALID)
1082		return ATF_COM;
1083	else
1084		return 0;
1085}
1086
1087/*
1088 *	Get an ARP cache entry.
1089 */
1090
1091static int arp_req_get(struct arpreq *r, struct net_device *dev)
1092{
1093	__be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1094	struct neighbour *neigh;
1095	int err = -ENXIO;
1096
1097	neigh = neigh_lookup(&arp_tbl, &ip, dev);
1098	if (neigh) {
1099		if (!(neigh->nud_state & NUD_NOARP)) {
1100			read_lock_bh(&neigh->lock);
1101			memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
1102			r->arp_flags = arp_state_to_flags(neigh);
1103			read_unlock_bh(&neigh->lock);
1104			r->arp_ha.sa_family = dev->type;
1105			strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1106			err = 0;
1107		}
1108		neigh_release(neigh);
1109	}
1110	return err;
1111}
1112
1113static int arp_invalidate(struct net_device *dev, __be32 ip)
1114{
1115	struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
1116	int err = -ENXIO;
1117	struct neigh_table *tbl = &arp_tbl;
1118
1119	if (neigh) {
1120		if (neigh->nud_state & ~NUD_NOARP)
1121			err = neigh_update(neigh, NULL, NUD_FAILED,
1122					   NEIGH_UPDATE_F_OVERRIDE|
1123					   NEIGH_UPDATE_F_ADMIN, 0);
1124		write_lock_bh(&tbl->lock);
1125		neigh_release(neigh);
1126		neigh_remove_one(neigh, tbl);
1127		write_unlock_bh(&tbl->lock);
1128	}
1129
1130	return err;
1131}
1132
1133static int arp_req_delete_public(struct net *net, struct arpreq *r,
1134		struct net_device *dev)
1135{
1136	__be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1137	__be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1138
1139	if (mask == htonl(0xFFFFFFFF))
1140		return pneigh_delete(&arp_tbl, net, &ip, dev);
1141
1142	if (mask)
1143		return -EINVAL;
1144
1145	return arp_req_set_proxy(net, dev, 0);
1146}
1147
1148static int arp_req_delete(struct net *net, struct arpreq *r,
1149			  struct net_device *dev)
1150{
1151	__be32 ip;
1152
1153	if (r->arp_flags & ATF_PUBL)
1154		return arp_req_delete_public(net, r, dev);
1155
1156	ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1157	if (!dev) {
1158		struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1159		if (IS_ERR(rt))
1160			return PTR_ERR(rt);
1161		dev = rt->dst.dev;
1162		ip_rt_put(rt);
1163		if (!dev)
1164			return -EINVAL;
1165	}
1166	return arp_invalidate(dev, ip);
1167}
1168
1169/*
1170 *	Handle an ARP layer I/O control request.
1171 */
1172
1173int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1174{
1175	int err;
1176	struct arpreq r;
1177	struct net_device *dev = NULL;
1178
1179	switch (cmd) {
1180	case SIOCDARP:
1181	case SIOCSARP:
1182		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1183			return -EPERM;
1184		fallthrough;
1185	case SIOCGARP:
1186		err = copy_from_user(&r, arg, sizeof(struct arpreq));
1187		if (err)
1188			return -EFAULT;
1189		break;
1190	default:
1191		return -EINVAL;
1192	}
1193
1194	if (r.arp_pa.sa_family != AF_INET)
1195		return -EPFNOSUPPORT;
1196
1197	if (!(r.arp_flags & ATF_PUBL) &&
1198	    (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1199		return -EINVAL;
1200	if (!(r.arp_flags & ATF_NETMASK))
1201		((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1202							   htonl(0xFFFFFFFFUL);
1203	rtnl_lock();
1204	if (r.arp_dev[0]) {
1205		err = -ENODEV;
1206		dev = __dev_get_by_name(net, r.arp_dev);
1207		if (!dev)
1208			goto out;
1209
1210		/* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1211		if (!r.arp_ha.sa_family)
1212			r.arp_ha.sa_family = dev->type;
1213		err = -EINVAL;
1214		if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1215			goto out;
1216	} else if (cmd == SIOCGARP) {
1217		err = -ENODEV;
1218		goto out;
1219	}
1220
1221	switch (cmd) {
1222	case SIOCDARP:
1223		err = arp_req_delete(net, &r, dev);
1224		break;
1225	case SIOCSARP:
1226		err = arp_req_set(net, &r, dev);
1227		break;
1228	case SIOCGARP:
1229		err = arp_req_get(&r, dev);
1230		break;
1231	}
1232out:
1233	rtnl_unlock();
1234	if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
1235		err = -EFAULT;
1236	return err;
1237}
1238
1239static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1240			    void *ptr)
1241{
1242	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
1243	struct netdev_notifier_change_info *change_info;
1244
1245	switch (event) {
1246	case NETDEV_CHANGEADDR:
1247		neigh_changeaddr(&arp_tbl, dev);
1248		rt_cache_flush(dev_net(dev));
1249		break;
1250	case NETDEV_CHANGE:
1251		change_info = ptr;
1252		if (change_info->flags_changed & IFF_NOARP)
1253			neigh_changeaddr(&arp_tbl, dev);
1254		if (!netif_carrier_ok(dev))
1255			neigh_carrier_down(&arp_tbl, dev);
1256		break;
1257	default:
1258		break;
1259	}
1260
1261	return NOTIFY_DONE;
1262}
1263
1264static struct notifier_block arp_netdev_notifier = {
1265	.notifier_call = arp_netdev_event,
1266};
1267
1268/* Note, that it is not on notifier chain.
1269   It is necessary, that this routine was called after route cache will be
1270   flushed.
1271 */
1272void arp_ifdown(struct net_device *dev)
1273{
1274	neigh_ifdown(&arp_tbl, dev);
1275}
1276
1277
1278/*
1279 *	Called once on startup.
1280 */
1281
1282static struct packet_type arp_packet_type __read_mostly = {
1283	.type =	cpu_to_be16(ETH_P_ARP),
1284	.func =	arp_rcv,
1285};
1286
1287static int arp_proc_init(void);
1288
1289void __init arp_init(void)
1290{
1291	neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl);
1292
1293	dev_add_pack(&arp_packet_type);
1294	arp_proc_init();
1295#ifdef CONFIG_SYSCTL
1296	neigh_sysctl_register(NULL, &arp_tbl.parms, NULL);
1297#endif
1298	register_netdevice_notifier(&arp_netdev_notifier);
1299}
1300
1301#ifdef CONFIG_PROC_FS
1302#if IS_ENABLED(CONFIG_AX25)
1303
1304/* ------------------------------------------------------------------------ */
1305/*
1306 *	ax25 -> ASCII conversion
1307 */
1308static void ax2asc2(ax25_address *a, char *buf)
1309{
1310	char c, *s;
1311	int n;
1312
1313	for (n = 0, s = buf; n < 6; n++) {
1314		c = (a->ax25_call[n] >> 1) & 0x7F;
1315
1316		if (c != ' ')
1317			*s++ = c;
1318	}
1319
1320	*s++ = '-';
1321	n = (a->ax25_call[6] >> 1) & 0x0F;
1322	if (n > 9) {
1323		*s++ = '1';
1324		n -= 10;
1325	}
1326
1327	*s++ = n + '0';
1328	*s++ = '\0';
1329
1330	if (*buf == '\0' || *buf == '-') {
1331		buf[0] = '*';
1332		buf[1] = '\0';
1333	}
1334}
1335#endif /* CONFIG_AX25 */
1336
1337#define HBUFFERLEN 30
1338
1339static void arp_format_neigh_entry(struct seq_file *seq,
1340				   struct neighbour *n)
1341{
1342	char hbuffer[HBUFFERLEN];
1343	int k, j;
1344	char tbuf[16];
1345	struct net_device *dev = n->dev;
1346	int hatype = dev->type;
1347
1348	read_lock(&n->lock);
1349	/* Convert hardware address to XX:XX:XX:XX ... form. */
1350#if IS_ENABLED(CONFIG_AX25)
1351	if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1352		ax2asc2((ax25_address *)n->ha, hbuffer);
1353	else {
1354#endif
1355	for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1356		hbuffer[k++] = hex_asc_hi(n->ha[j]);
1357		hbuffer[k++] = hex_asc_lo(n->ha[j]);
1358		hbuffer[k++] = ':';
1359	}
1360	if (k != 0)
1361		--k;
1362	hbuffer[k] = 0;
1363#if IS_ENABLED(CONFIG_AX25)
1364	}
1365#endif
1366	sprintf(tbuf, "%pI4", n->primary_key);
1367	seq_printf(seq, "%-16s 0x%-10x0x%-10x%-17s     *        %s\n",
1368		   tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1369	read_unlock(&n->lock);
1370}
1371
1372static void arp_format_pneigh_entry(struct seq_file *seq,
1373				    struct pneigh_entry *n)
1374{
1375	struct net_device *dev = n->dev;
1376	int hatype = dev ? dev->type : 0;
1377	char tbuf[16];
1378
1379	sprintf(tbuf, "%pI4", n->key);
1380	seq_printf(seq, "%-16s 0x%-10x0x%-10x%s     *        %s\n",
1381		   tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1382		   dev ? dev->name : "*");
1383}
1384
1385static int arp_seq_show(struct seq_file *seq, void *v)
1386{
1387	if (v == SEQ_START_TOKEN) {
1388		seq_puts(seq, "IP address       HW type     Flags       "
1389			      "HW address            Mask     Device\n");
1390	} else {
1391		struct neigh_seq_state *state = seq->private;
1392
1393		if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1394			arp_format_pneigh_entry(seq, v);
1395		else
1396			arp_format_neigh_entry(seq, v);
1397	}
1398
1399	return 0;
1400}
1401
1402static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1403{
1404	/* Don't want to confuse "arp -a" w/ magic entries,
1405	 * so we tell the generic iterator to skip NUD_NOARP.
1406	 */
1407	return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1408}
1409
1410/* ------------------------------------------------------------------------ */
1411
1412static const struct seq_operations arp_seq_ops = {
1413	.start	= arp_seq_start,
1414	.next	= neigh_seq_next,
1415	.stop	= neigh_seq_stop,
1416	.show	= arp_seq_show,
1417};
1418
1419/* ------------------------------------------------------------------------ */
1420
1421static int __net_init arp_net_init(struct net *net)
1422{
1423	if (!proc_create_net("arp", 0444, net->proc_net, &arp_seq_ops,
1424			sizeof(struct neigh_seq_state)))
1425		return -ENOMEM;
1426	return 0;
1427}
1428
1429static void __net_exit arp_net_exit(struct net *net)
1430{
1431	remove_proc_entry("arp", net->proc_net);
1432}
1433
1434static struct pernet_operations arp_net_ops = {
1435	.init = arp_net_init,
1436	.exit = arp_net_exit,
1437};
1438
1439static int __init arp_proc_init(void)
1440{
1441	return register_pernet_subsys(&arp_net_ops);
1442}
1443
1444#else /* CONFIG_PROC_FS */
1445
1446static int __init arp_proc_init(void)
1447{
1448	return 0;
1449}
1450
1451#endif /* CONFIG_PROC_FS */