1/* linux/net/ipv4/arp.c
   2 *
   3 * Copyright (C) 1994 by Florian  La Roche
   4 *
   5 * This module implements the Address Resolution Protocol ARP (RFC 826),
   6 * which is used to convert IP addresses (or in the future maybe other
   7 * high-level addresses) into a low-level hardware address (like an Ethernet
   8 * address).
   9 *
  10 * This program is free software; you can redistribute it and/or
  11 * modify it under the terms of the GNU General Public License
  12 * as published by the Free Software Foundation; either version
  13 * 2 of the License, or (at your option) any later version.
  14 *
  15 * Fixes:
  16 *		Alan Cox	:	Removed the Ethernet assumptions in
  17 *					Florian's code
  18 *		Alan Cox	:	Fixed some small errors in the ARP
  19 *					logic
  20 *		Alan Cox	:	Allow >4K in /proc
  21 *		Alan Cox	:	Make ARP add its own protocol entry
  22 *		Ross Martin     :       Rewrote arp_rcv() and arp_get_info()
  23 *		Stephen Henson	:	Add AX25 support to arp_get_info()
  24 *		Alan Cox	:	Drop data when a device is downed.
  25 *		Alan Cox	:	Use init_timer().
  26 *		Alan Cox	:	Double lock fixes.
  27 *		Martin Seine	:	Move the arphdr structure
  28 *					to if_arp.h for compatibility.
  29 *					with BSD based programs.
  30 *		Andrew Tridgell :       Added ARP netmask code and
  31 *					re-arranged proxy handling.
  32 *		Alan Cox	:	Changed to use notifiers.
  33 *		Niibe Yutaka	:	Reply for this device or proxies only.
  34 *		Alan Cox	:	Don't proxy across hardware types!
  35 *		Jonathan Naylor :	Added support for NET/ROM.
  36 *		Mike Shaver     :       RFC1122 checks.
  37 *		Jonathan Naylor :	Only lookup the hardware address for
  38 *					the correct hardware type.
  39 *		Germano Caronni	:	Assorted subtle races.
  40 *		Craig Schlenter :	Don't modify permanent entry
  41 *					during arp_rcv.
  42 *		Russ Nelson	:	Tidied up a few bits.
  43 *		Alexey Kuznetsov:	Major changes to caching and behaviour,
  44 *					eg intelligent arp probing and
  45 *					generation
  46 *					of host down events.
  47 *		Alan Cox	:	Missing unlock in device events.
  48 *		Eckes		:	ARP ioctl control errors.
  49 *		Alexey Kuznetsov:	Arp free fix.
  50 *		Manuel Rodriguez:	Gratuitous ARP.
  51 *              Jonathan Layes  :       Added arpd support through kerneld
  52 *                                      message queue (960314)
  53 *		Mike Shaver	:	/proc/sys/net/ipv4/arp_* support
  54 *		Mike McLagan    :	Routing by source
  55 *		Stuart Cheshire	:	Metricom and grat arp fixes
  56 *					*** FOR 2.1 clean this up ***
  57 *		Lawrence V. Stefani: (08/12/96) Added FDDI support.
  58 *		Alan Cox	:	Took the AP1000 nasty FDDI hack and
  59 *					folded into the mainstream FDDI code.
  60 *					Ack spit, Linus how did you allow that
  61 *					one in...
  62 *		Jes Sorensen	:	Make FDDI work again in 2.1.x and
  63 *					clean up the APFDDI & gen. FDDI bits.
  64 *		Alexey Kuznetsov:	new arp state machine;
  65 *					now it is in net/core/neighbour.c.
  66 *		Krzysztof Halasa:	Added Frame Relay ARP support.
  67 *		Arnaldo C. Melo :	convert /proc/net/arp to seq_file
  68 *		Shmulik Hen:		Split arp_send to arp_create and
  69 *					arp_xmit so intermediate drivers like
  70 *					bonding can change the skb before
  71 *					sending (e.g. insert 8021q tag).
  72 *		Harald Welte	:	convert to make use of jenkins hash
  73 *		Jesper D. Brouer:       Proxy ARP PVLAN RFC 3069 support.
  74 */
  75
  76#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  77
  78#include <linux/module.h>
  79#include <linux/types.h>
  80#include <linux/string.h>
  81#include <linux/kernel.h>
  82#include <linux/capability.h>
  83#include <linux/socket.h>
  84#include <linux/sockios.h>
  85#include <linux/errno.h>
  86#include <linux/in.h>
  87#include <linux/mm.h>
  88#include <linux/inet.h>
  89#include <linux/inetdevice.h>
  90#include <linux/netdevice.h>
  91#include <linux/etherdevice.h>
  92#include <linux/fddidevice.h>
  93#include <linux/if_arp.h>
  94#include <linux/skbuff.h>
  95#include <linux/proc_fs.h>
  96#include <linux/seq_file.h>
  97#include <linux/stat.h>
  98#include <linux/init.h>
  99#include <linux/net.h>
 100#include <linux/rcupdate.h>
 101#include <linux/slab.h>
 102#ifdef CONFIG_SYSCTL
 103#include <linux/sysctl.h>
 104#endif
 105
 106#include <net/net_namespace.h>
 107#include <net/ip.h>
 108#include <net/icmp.h>
 109#include <net/route.h>
 110#include <net/protocol.h>
 111#include <net/tcp.h>
 112#include <net/sock.h>
 113#include <net/arp.h>
 114#include <net/ax25.h>
 115#include <net/netrom.h>
 116#include <net/dst_metadata.h>
 117#include <net/ip_tunnels.h>
 118
 119#include <linux/uaccess.h>
 120
 121#include <linux/netfilter_arp.h>
 122
 123/*
 124 *	Interface to generic neighbour cache.
 125 */
 126static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd);
 127static bool arp_key_eq(const struct neighbour *n, const void *pkey);
 128static int arp_constructor(struct neighbour *neigh);
 129static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
 130static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
 131static void parp_redo(struct sk_buff *skb);
 132
 133static const struct neigh_ops arp_generic_ops = {
 134	.family =		AF_INET,
 135	.solicit =		arp_solicit,
 136	.error_report =		arp_error_report,
 137	.output =		neigh_resolve_output,
 138	.connected_output =	neigh_connected_output,
 139};
 140
 141static const struct neigh_ops arp_hh_ops = {
 142	.family =		AF_INET,
 143	.solicit =		arp_solicit,
 144	.error_report =		arp_error_report,
 145	.output =		neigh_resolve_output,
 146	.connected_output =	neigh_resolve_output,
 147};
 148
 149static const struct neigh_ops arp_direct_ops = {
 150	.family =		AF_INET,
 151	.output =		neigh_direct_output,
 152	.connected_output =	neigh_direct_output,
 153};
 154
 155struct neigh_table arp_tbl = {
 156	.family		= AF_INET,
 157	.key_len	= 4,
 158	.protocol	= cpu_to_be16(ETH_P_IP),
 159	.hash		= arp_hash,
 160	.key_eq		= arp_key_eq,
 161	.constructor	= arp_constructor,
 162	.proxy_redo	= parp_redo,
 163	.id		= "arp_cache",
 164	.parms		= {
 165		.tbl			= &arp_tbl,
 166		.reachable_time		= 30 * HZ,
 167		.data	= {
 168			[NEIGH_VAR_MCAST_PROBES] = 3,
 169			[NEIGH_VAR_UCAST_PROBES] = 3,
 170			[NEIGH_VAR_RETRANS_TIME] = 1 * HZ,
 171			[NEIGH_VAR_BASE_REACHABLE_TIME] = 30 * HZ,
 172			[NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ,
 173			[NEIGH_VAR_GC_STALETIME] = 60 * HZ,
 174			[NEIGH_VAR_QUEUE_LEN_BYTES] = SK_WMEM_MAX,
 175			[NEIGH_VAR_PROXY_QLEN] = 64,
 176			[NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ,
 177			[NEIGH_VAR_PROXY_DELAY]	= (8 * HZ) / 10,
 178			[NEIGH_VAR_LOCKTIME] = 1 * HZ,
 179		},
 180	},
 181	.gc_interval	= 30 * HZ,
 182	.gc_thresh1	= 128,
 183	.gc_thresh2	= 512,
 184	.gc_thresh3	= 1024,
 185};
 186EXPORT_SYMBOL(arp_tbl);
 187
 188int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir)
 189{
 190	switch (dev->type) {
 191	case ARPHRD_ETHER:
 192	case ARPHRD_FDDI:
 193	case ARPHRD_IEEE802:
 194		ip_eth_mc_map(addr, haddr);
 195		return 0;
 196	case ARPHRD_INFINIBAND:
 197		ip_ib_mc_map(addr, dev->broadcast, haddr);
 198		return 0;
 199	case ARPHRD_IPGRE:
 200		ip_ipgre_mc_map(addr, dev->broadcast, haddr);
 201		return 0;
 202	default:
 203		if (dir) {
 204			memcpy(haddr, dev->broadcast, dev->addr_len);
 205			return 0;
 206		}
 207	}
 208	return -EINVAL;
 209}
 210
 211
 212static u32 arp_hash(const void *pkey,
 213		    const struct net_device *dev,
 214		    __u32 *hash_rnd)
 215{
 216	return arp_hashfn(pkey, dev, hash_rnd);
 217}
 218
 219static bool arp_key_eq(const struct neighbour *neigh, const void *pkey)
 220{
 221	return neigh_key_eq32(neigh, pkey);
 222}
 223
 224static int arp_constructor(struct neighbour *neigh)
 225{
 226	__be32 addr;
 227	struct net_device *dev = neigh->dev;
 228	struct in_device *in_dev;
 229	struct neigh_parms *parms;
 230	u32 inaddr_any = INADDR_ANY;
 231
 232	if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT))
 233		memcpy(neigh->primary_key, &inaddr_any, arp_tbl.key_len);
 234
 235	addr = *(__be32 *)neigh->primary_key;
 236	rcu_read_lock();
 237	in_dev = __in_dev_get_rcu(dev);
 238	if (!in_dev) {
 239		rcu_read_unlock();
 240		return -EINVAL;
 241	}
 242
 243	neigh->type = inet_addr_type_dev_table(dev_net(dev), dev, addr);
 244
 245	parms = in_dev->arp_parms;
 246	__neigh_parms_put(neigh->parms);
 247	neigh->parms = neigh_parms_clone(parms);
 248	rcu_read_unlock();
 249
 250	if (!dev->header_ops) {
 251		neigh->nud_state = NUD_NOARP;
 252		neigh->ops = &arp_direct_ops;
 253		neigh->output = neigh_direct_output;
 254	} else {
 255		/* Good devices (checked by reading texts, but only Ethernet is
 256		   tested)
 257
 258		   ARPHRD_ETHER: (ethernet, apfddi)
 259		   ARPHRD_FDDI: (fddi)
 260		   ARPHRD_IEEE802: (tr)
 261		   ARPHRD_METRICOM: (strip)
 262		   ARPHRD_ARCNET:
 263		   etc. etc. etc.
 264
 265		   ARPHRD_IPDDP will also work, if author repairs it.
 266		   I did not it, because this driver does not work even
 267		   in old paradigm.
 268		 */
 269
 270		if (neigh->type == RTN_MULTICAST) {
 271			neigh->nud_state = NUD_NOARP;
 272			arp_mc_map(addr, neigh->ha, dev, 1);
 273		} else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) {
 274			neigh->nud_state = NUD_NOARP;
 275			memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
 276		} else if (neigh->type == RTN_BROADCAST ||
 277			   (dev->flags & IFF_POINTOPOINT)) {
 278			neigh->nud_state = NUD_NOARP;
 279			memcpy(neigh->ha, dev->broadcast, dev->addr_len);
 280		}
 281
 282		if (dev->header_ops->cache)
 283			neigh->ops = &arp_hh_ops;
 284		else
 285			neigh->ops = &arp_generic_ops;
 286
 287		if (neigh->nud_state & NUD_VALID)
 288			neigh->output = neigh->ops->connected_output;
 289		else
 290			neigh->output = neigh->ops->output;
 291	}
 292	return 0;
 293}
 294
 295static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
 296{
 297	dst_link_failure(skb);
 298	kfree_skb(skb);
 299}
 300
 301/* Create and send an arp packet. */
 302static void arp_send_dst(int type, int ptype, __be32 dest_ip,
 303			 struct net_device *dev, __be32 src_ip,
 304			 const unsigned char *dest_hw,
 305			 const unsigned char *src_hw,
 306			 const unsigned char *target_hw,
 307			 struct dst_entry *dst)
 308{
 309	struct sk_buff *skb;
 310
 311	/* arp on this interface. */
 312	if (dev->flags & IFF_NOARP)
 313		return;
 314
 315	skb = arp_create(type, ptype, dest_ip, dev, src_ip,
 316			 dest_hw, src_hw, target_hw);
 317	if (!skb)
 318		return;
 319
 320	skb_dst_set(skb, dst_clone(dst));
 321	arp_xmit(skb);
 322}
 323
 324void arp_send(int type, int ptype, __be32 dest_ip,
 325	      struct net_device *dev, __be32 src_ip,
 326	      const unsigned char *dest_hw, const unsigned char *src_hw,
 327	      const unsigned char *target_hw)
 328{
 329	arp_send_dst(type, ptype, dest_ip, dev, src_ip, dest_hw, src_hw,
 330		     target_hw, NULL);
 331}
 332EXPORT_SYMBOL(arp_send);
 333
 334static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
 335{
 336	__be32 saddr = 0;
 337	u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL;
 338	struct net_device *dev = neigh->dev;
 339	__be32 target = *(__be32 *)neigh->primary_key;
 340	int probes = atomic_read(&neigh->probes);
 341	struct in_device *in_dev;
 342	struct dst_entry *dst = NULL;
 343
 344	rcu_read_lock();
 345	in_dev = __in_dev_get_rcu(dev);
 346	if (!in_dev) {
 347		rcu_read_unlock();
 348		return;
 349	}
 350	switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
 351	default:
 352	case 0:		/* By default announce any local IP */
 353		if (skb && inet_addr_type_dev_table(dev_net(dev), dev,
 354					  ip_hdr(skb)->saddr) == RTN_LOCAL)
 355			saddr = ip_hdr(skb)->saddr;
 356		break;
 357	case 1:		/* Restrict announcements of saddr in same subnet */
 358		if (!skb)
 359			break;
 360		saddr = ip_hdr(skb)->saddr;
 361		if (inet_addr_type_dev_table(dev_net(dev), dev,
 362					     saddr) == RTN_LOCAL) {
 363			/* saddr should be known to target */
 364			if (inet_addr_onlink(in_dev, target, saddr))
 365				break;
 366		}
 367		saddr = 0;
 368		break;
 369	case 2:		/* Avoid secondary IPs, get a primary/preferred one */
 370		break;
 371	}
 372	rcu_read_unlock();
 373
 374	if (!saddr)
 375		saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
 376
 377	probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES);
 378	if (probes < 0) {
 379		if (!(neigh->nud_state & NUD_VALID))
 380			pr_debug("trying to ucast probe in NUD_INVALID\n");
 381		neigh_ha_snapshot(dst_ha, neigh, dev);
 382		dst_hw = dst_ha;
 383	} else {
 384		probes -= NEIGH_VAR(neigh->parms, APP_PROBES);
 385		if (probes < 0) {
 386			neigh_app_ns(neigh);
 387			return;
 388		}
 389	}
 390
 391	if (skb && !(dev->priv_flags & IFF_XMIT_DST_RELEASE))
 392		dst = skb_dst(skb);
 393	arp_send_dst(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
 394		     dst_hw, dev->dev_addr, NULL, dst);
 395}
 396
 397static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip)
 398{
 399	struct net *net = dev_net(in_dev->dev);
 400	int scope;
 401
 402	switch (IN_DEV_ARP_IGNORE(in_dev)) {
 403	case 0:	/* Reply, the tip is already validated */
 404		return 0;
 405	case 1:	/* Reply only if tip is configured on the incoming interface */
 406		sip = 0;
 407		scope = RT_SCOPE_HOST;
 408		break;
 409	case 2:	/*
 410		 * Reply only if tip is configured on the incoming interface
 411		 * and is in same subnet as sip
 412		 */
 413		scope = RT_SCOPE_HOST;
 414		break;
 415	case 3:	/* Do not reply for scope host addresses */
 416		sip = 0;
 417		scope = RT_SCOPE_LINK;
 418		in_dev = NULL;
 419		break;
 420	case 4:	/* Reserved */
 421	case 5:
 422	case 6:
 423	case 7:
 424		return 0;
 425	case 8:	/* Do not reply */
 426		return 1;
 427	default:
 428		return 0;
 429	}
 430	return !inet_confirm_addr(net, in_dev, sip, tip, scope);
 431}
 432
 433static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
 434{
 435	struct rtable *rt;
 436	int flag = 0;
 437	/*unsigned long now; */
 438	struct net *net = dev_net(dev);
 439
 440	rt = ip_route_output(net, sip, tip, 0, l3mdev_master_ifindex_rcu(dev));
 441	if (IS_ERR(rt))
 442		return 1;
 443	if (rt->dst.dev != dev) {
 444		__NET_INC_STATS(net, LINUX_MIB_ARPFILTER);
 445		flag = 1;
 446	}
 447	ip_rt_put(rt);
 448	return flag;
 449}
 450
 451/*
 452 * Check if we can use proxy ARP for this path
 453 */
 454static inline int arp_fwd_proxy(struct in_device *in_dev,
 455				struct net_device *dev,	struct rtable *rt)
 456{
 457	struct in_device *out_dev;
 458	int imi, omi = -1;
 459
 460	if (rt->dst.dev == dev)
 461		return 0;
 462
 463	if (!IN_DEV_PROXY_ARP(in_dev))
 464		return 0;
 465	imi = IN_DEV_MEDIUM_ID(in_dev);
 466	if (imi == 0)
 467		return 1;
 468	if (imi == -1)
 469		return 0;
 470
 471	/* place to check for proxy_arp for routes */
 472
 473	out_dev = __in_dev_get_rcu(rt->dst.dev);
 474	if (out_dev)
 475		omi = IN_DEV_MEDIUM_ID(out_dev);
 476
 477	return omi != imi && omi != -1;
 478}
 479
 480/*
 481 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
 482 *
 483 * RFC3069 supports proxy arp replies back to the same interface.  This
 484 * is done to support (ethernet) switch features, like RFC 3069, where
 485 * the individual ports are not allowed to communicate with each
 486 * other, BUT they are allowed to talk to the upstream router.  As
 487 * described in RFC 3069, it is possible to allow these hosts to
 488 * communicate through the upstream router, by proxy_arp'ing.
 489 *
 490 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
 491 *
 492 *  This technology is known by different names:
 493 *    In RFC 3069 it is called VLAN Aggregation.
 494 *    Cisco and Allied Telesyn call it Private VLAN.
 495 *    Hewlett-Packard call it Source-Port filtering or port-isolation.
 496 *    Ericsson call it MAC-Forced Forwarding (RFC Draft).
 497 *
 498 */
 499static inline int arp_fwd_pvlan(struct in_device *in_dev,
 500				struct net_device *dev,	struct rtable *rt,
 501				__be32 sip, __be32 tip)
 502{
 503	/* Private VLAN is only concerned about the same ethernet segment */
 504	if (rt->dst.dev != dev)
 505		return 0;
 506
 507	/* Don't reply on self probes (often done by windowz boxes)*/
 508	if (sip == tip)
 509		return 0;
 510
 511	if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
 512		return 1;
 513	else
 514		return 0;
 515}
 516
 517/*
 518 *	Interface to link layer: send routine and receive handler.
 519 */
 520
 521/*
 522 *	Create an arp packet. If dest_hw is not set, we create a broadcast
 523 *	message.
 524 */
 525struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
 526			   struct net_device *dev, __be32 src_ip,
 527			   const unsigned char *dest_hw,
 528			   const unsigned char *src_hw,
 529			   const unsigned char *target_hw)
 530{
 531	struct sk_buff *skb;
 532	struct arphdr *arp;
 533	unsigned char *arp_ptr;
 534	int hlen = LL_RESERVED_SPACE(dev);
 535	int tlen = dev->needed_tailroom;
 536
 537	/*
 538	 *	Allocate a buffer
 539	 */
 540
 541	skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
 542	if (!skb)
 543		return NULL;
 544
 545	skb_reserve(skb, hlen);
 546	skb_reset_network_header(skb);
 547	arp = skb_put(skb, arp_hdr_len(dev));
 548	skb->dev = dev;
 549	skb->protocol = htons(ETH_P_ARP);
 550	if (!src_hw)
 551		src_hw = dev->dev_addr;
 552	if (!dest_hw)
 553		dest_hw = dev->broadcast;
 554
 555	/*
 556	 *	Fill the device header for the ARP frame
 557	 */
 558	if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
 559		goto out;
 560
 561	/*
 562	 * Fill out the arp protocol part.
 563	 *
 564	 * The arp hardware type should match the device type, except for FDDI,
 565	 * which (according to RFC 1390) should always equal 1 (Ethernet).
 566	 */
 567	/*
 568	 *	Exceptions everywhere. AX.25 uses the AX.25 PID value not the
 569	 *	DIX code for the protocol. Make these device structure fields.
 570	 */
 571	switch (dev->type) {
 572	default:
 573		arp->ar_hrd = htons(dev->type);
 574		arp->ar_pro = htons(ETH_P_IP);
 575		break;
 576
 577#if IS_ENABLED(CONFIG_AX25)
 578	case ARPHRD_AX25:
 579		arp->ar_hrd = htons(ARPHRD_AX25);
 580		arp->ar_pro = htons(AX25_P_IP);
 581		break;
 582
 583#if IS_ENABLED(CONFIG_NETROM)
 584	case ARPHRD_NETROM:
 585		arp->ar_hrd = htons(ARPHRD_NETROM);
 586		arp->ar_pro = htons(AX25_P_IP);
 587		break;
 588#endif
 589#endif
 590
 591#if IS_ENABLED(CONFIG_FDDI)
 592	case ARPHRD_FDDI:
 593		arp->ar_hrd = htons(ARPHRD_ETHER);
 594		arp->ar_pro = htons(ETH_P_IP);
 595		break;
 596#endif
 597	}
 598
 599	arp->ar_hln = dev->addr_len;
 600	arp->ar_pln = 4;
 601	arp->ar_op = htons(type);
 602
 603	arp_ptr = (unsigned char *)(arp + 1);
 604
 605	memcpy(arp_ptr, src_hw, dev->addr_len);
 606	arp_ptr += dev->addr_len;
 607	memcpy(arp_ptr, &src_ip, 4);
 608	arp_ptr += 4;
 609
 610	switch (dev->type) {
 611#if IS_ENABLED(CONFIG_FIREWIRE_NET)
 612	case ARPHRD_IEEE1394:
 613		break;
 614#endif
 615	default:
 616		if (target_hw)
 617			memcpy(arp_ptr, target_hw, dev->addr_len);
 618		else
 619			memset(arp_ptr, 0, dev->addr_len);
 620		arp_ptr += dev->addr_len;
 621	}
 622	memcpy(arp_ptr, &dest_ip, 4);
 623
 624	return skb;
 625
 626out:
 627	kfree_skb(skb);
 628	return NULL;
 629}
 630EXPORT_SYMBOL(arp_create);
 631
 632static int arp_xmit_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 633{
 634	return dev_queue_xmit(skb);
 635}
 636
 637/*
 638 *	Send an arp packet.
 639 */
 640void arp_xmit(struct sk_buff *skb)
 641{
 642	/* Send it off, maybe filter it using firewalling first.  */
 643	NF_HOOK(NFPROTO_ARP, NF_ARP_OUT,
 644		dev_net(skb->dev), NULL, skb, NULL, skb->dev,
 645		arp_xmit_finish);
 646}
 647EXPORT_SYMBOL(arp_xmit);
 648
 649static bool arp_is_garp(struct net *net, struct net_device *dev,
 650			int *addr_type, __be16 ar_op,
 651			__be32 sip, __be32 tip,
 652			unsigned char *sha, unsigned char *tha)
 653{
 654	bool is_garp = tip == sip;
 655
 656	/* Gratuitous ARP _replies_ also require target hwaddr to be
 657	 * the same as source.
 658	 */
 659	if (is_garp && ar_op == htons(ARPOP_REPLY))
 660		is_garp =
 661			/* IPv4 over IEEE 1394 doesn't provide target
 662			 * hardware address field in its ARP payload.
 663			 */
 664			tha &&
 665			!memcmp(tha, sha, dev->addr_len);
 666
 667	if (is_garp) {
 668		*addr_type = inet_addr_type_dev_table(net, dev, sip);
 669		if (*addr_type != RTN_UNICAST)
 670			is_garp = false;
 671	}
 672	return is_garp;
 673}
 674
 675/*
 676 *	Process an arp request.
 677 */
 678
 679static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb)
 680{
 681	struct net_device *dev = skb->dev;
 682	struct in_device *in_dev = __in_dev_get_rcu(dev);
 683	struct arphdr *arp;
 684	unsigned char *arp_ptr;
 685	struct rtable *rt;
 686	unsigned char *sha;
 687	unsigned char *tha = NULL;
 688	__be32 sip, tip;
 689	u16 dev_type = dev->type;
 690	int addr_type;
 691	struct neighbour *n;
 692	struct dst_entry *reply_dst = NULL;
 693	bool is_garp = false;
 694
 695	/* arp_rcv below verifies the ARP header and verifies the device
 696	 * is ARP'able.
 697	 */
 698
 699	if (!in_dev)
 700		goto out_free_skb;
 701
 702	arp = arp_hdr(skb);
 703
 704	switch (dev_type) {
 705	default:
 706		if (arp->ar_pro != htons(ETH_P_IP) ||
 707		    htons(dev_type) != arp->ar_hrd)
 708			goto out_free_skb;
 709		break;
 710	case ARPHRD_ETHER:
 711	case ARPHRD_FDDI:
 712	case ARPHRD_IEEE802:
 713		/*
 714		 * ETHERNET, and Fibre Channel (which are IEEE 802
 715		 * devices, according to RFC 2625) devices will accept ARP
 716		 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
 717		 * This is the case also of FDDI, where the RFC 1390 says that
 718		 * FDDI devices should accept ARP hardware of (1) Ethernet,
 719		 * however, to be more robust, we'll accept both 1 (Ethernet)
 720		 * or 6 (IEEE 802.2)
 721		 */
 722		if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
 723		     arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
 724		    arp->ar_pro != htons(ETH_P_IP))
 725			goto out_free_skb;
 726		break;
 727	case ARPHRD_AX25:
 728		if (arp->ar_pro != htons(AX25_P_IP) ||
 729		    arp->ar_hrd != htons(ARPHRD_AX25))
 730			goto out_free_skb;
 731		break;
 732	case ARPHRD_NETROM:
 733		if (arp->ar_pro != htons(AX25_P_IP) ||
 734		    arp->ar_hrd != htons(ARPHRD_NETROM))
 735			goto out_free_skb;
 736		break;
 737	}
 738
 739	/* Understand only these message types */
 740
 741	if (arp->ar_op != htons(ARPOP_REPLY) &&
 742	    arp->ar_op != htons(ARPOP_REQUEST))
 743		goto out_free_skb;
 744
 745/*
 746 *	Extract fields
 747 */
 748	arp_ptr = (unsigned char *)(arp + 1);
 749	sha	= arp_ptr;
 750	arp_ptr += dev->addr_len;
 751	memcpy(&sip, arp_ptr, 4);
 752	arp_ptr += 4;
 753	switch (dev_type) {
 754#if IS_ENABLED(CONFIG_FIREWIRE_NET)
 755	case ARPHRD_IEEE1394:
 756		break;
 757#endif
 758	default:
 759		tha = arp_ptr;
 760		arp_ptr += dev->addr_len;
 761	}
 762	memcpy(&tip, arp_ptr, 4);
 763/*
 764 *	Check for bad requests for 127.x.x.x and requests for multicast
 765 *	addresses.  If this is one such, delete it.
 766 */
 767	if (ipv4_is_multicast(tip) ||
 768	    (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip)))
 769		goto out_free_skb;
 770
 771 /*
 772  *	For some 802.11 wireless deployments (and possibly other networks),
 773  *	there will be an ARP proxy and gratuitous ARP frames are attacks
 774  *	and thus should not be accepted.
 775  */
 776	if (sip == tip && IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP))
 777		goto out_free_skb;
 778
 779/*
 780 *     Special case: We must set Frame Relay source Q.922 address
 781 */
 782	if (dev_type == ARPHRD_DLCI)
 783		sha = dev->broadcast;
 784
 785/*
 786 *  Process entry.  The idea here is we want to send a reply if it is a
 787 *  request for us or if it is a request for someone else that we hold
 788 *  a proxy for.  We want to add an entry to our cache if it is a reply
 789 *  to us or if it is a request for our address.
 790 *  (The assumption for this last is that if someone is requesting our
 791 *  address, they are probably intending to talk to us, so it saves time
 792 *  if we cache their address.  Their address is also probably not in
 793 *  our cache, since ours is not in their cache.)
 794 *
 795 *  Putting this another way, we only care about replies if they are to
 796 *  us, in which case we add them to the cache.  For requests, we care
 797 *  about those for us and those for our proxies.  We reply to both,
 798 *  and in the case of requests for us we add the requester to the arp
 799 *  cache.
 800 */
 801
 802	if (arp->ar_op == htons(ARPOP_REQUEST) && skb_metadata_dst(skb))
 803		reply_dst = (struct dst_entry *)
 804			    iptunnel_metadata_reply(skb_metadata_dst(skb),
 805						    GFP_ATOMIC);
 806
 807	/* Special case: IPv4 duplicate address detection packet (RFC2131) */
 808	if (sip == 0) {
 809		if (arp->ar_op == htons(ARPOP_REQUEST) &&
 810		    inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL &&
 811		    !arp_ignore(in_dev, sip, tip))
 812			arp_send_dst(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip,
 813				     sha, dev->dev_addr, sha, reply_dst);
 814		goto out_consume_skb;
 815	}
 816
 817	if (arp->ar_op == htons(ARPOP_REQUEST) &&
 818	    ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
 819
 820		rt = skb_rtable(skb);
 821		addr_type = rt->rt_type;
 822
 823		if (addr_type == RTN_LOCAL) {
 824			int dont_send;
 825
 826			dont_send = arp_ignore(in_dev, sip, tip);
 827			if (!dont_send && IN_DEV_ARPFILTER(in_dev))
 828				dont_send = arp_filter(sip, tip, dev);
 829			if (!dont_send) {
 830				n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
 831				if (n) {
 832					arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
 833						     sip, dev, tip, sha,
 834						     dev->dev_addr, sha,
 835						     reply_dst);
 836					neigh_release(n);
 837				}
 838			}
 839			goto out_consume_skb;
 840		} else if (IN_DEV_FORWARD(in_dev)) {
 841			if (addr_type == RTN_UNICAST  &&
 842			    (arp_fwd_proxy(in_dev, dev, rt) ||
 843			     arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
 844			     (rt->dst.dev != dev &&
 845			      pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
 846				n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
 847				if (n)
 848					neigh_release(n);
 849
 850				if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
 851				    skb->pkt_type == PACKET_HOST ||
 852				    NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) {
 853					arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
 854						     sip, dev, tip, sha,
 855						     dev->dev_addr, sha,
 856						     reply_dst);
 857				} else {
 858					pneigh_enqueue(&arp_tbl,
 859						       in_dev->arp_parms, skb);
 860					goto out_free_dst;
 861				}
 862				goto out_consume_skb;
 863			}
 864		}
 865	}
 866
 867	/* Update our ARP tables */
 868
 869	n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
 870
 871	addr_type = -1;
 872	if (n || IN_DEV_ARP_ACCEPT(in_dev)) {
 873		is_garp = arp_is_garp(net, dev, &addr_type, arp->ar_op,
 874				      sip, tip, sha, tha);
 875	}
 876
 877	if (IN_DEV_ARP_ACCEPT(in_dev)) {
 878		/* Unsolicited ARP is not accepted by default.
 879		   It is possible, that this option should be enabled for some
 880		   devices (strip is candidate)
 881		 */
 882		if (!n &&
 883		    (is_garp ||
 884		     (arp->ar_op == htons(ARPOP_REPLY) &&
 885		      (addr_type == RTN_UNICAST ||
 886		       (addr_type < 0 &&
 887			/* postpone calculation to as late as possible */
 888			inet_addr_type_dev_table(net, dev, sip) ==
 889				RTN_UNICAST)))))
 890			n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
 891	}
 892
 893	if (n) {
 894		int state = NUD_REACHABLE;
 895		int override;
 896
 897		/* If several different ARP replies follows back-to-back,
 898		   use the FIRST one. It is possible, if several proxy
 899		   agents are active. Taking the first reply prevents
 900		   arp trashing and chooses the fastest router.
 901		 */
 902		override = time_after(jiffies,
 903				      n->updated +
 904				      NEIGH_VAR(n->parms, LOCKTIME)) ||
 905			   is_garp;
 906
 907		/* Broadcast replies and request packets
 908		   do not assert neighbour reachability.
 909		 */
 910		if (arp->ar_op != htons(ARPOP_REPLY) ||
 911		    skb->pkt_type != PACKET_HOST)
 912			state = NUD_STALE;
 913		neigh_update(n, sha, state,
 914			     override ? NEIGH_UPDATE_F_OVERRIDE : 0, 0);
 915		neigh_release(n);
 916	}
 917
 918out_consume_skb:
 919	consume_skb(skb);
 920
 921out_free_dst:
 922	dst_release(reply_dst);
 923	return NET_RX_SUCCESS;
 924
 925out_free_skb:
 926	kfree_skb(skb);
 927	return NET_RX_DROP;
 928}
 929
 930static void parp_redo(struct sk_buff *skb)
 931{
 932	arp_process(dev_net(skb->dev), NULL, skb);
 933}
 934
 935
 936/*
 937 *	Receive an arp request from the device layer.
 938 */
 939
 940static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
 941		   struct packet_type *pt, struct net_device *orig_dev)
 942{
 943	const struct arphdr *arp;
 944
 945	/* do not tweak dropwatch on an ARP we will ignore */
 946	if (dev->flags & IFF_NOARP ||
 947	    skb->pkt_type == PACKET_OTHERHOST ||
 948	    skb->pkt_type == PACKET_LOOPBACK)
 949		goto consumeskb;
 950
 951	skb = skb_share_check(skb, GFP_ATOMIC);
 952	if (!skb)
 953		goto out_of_mem;
 954
 955	/* ARP header, plus 2 device addresses, plus 2 IP addresses.  */
 956	if (!pskb_may_pull(skb, arp_hdr_len(dev)))
 957		goto freeskb;
 958
 959	arp = arp_hdr(skb);
 960	if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4)
 961		goto freeskb;
 962
 963	memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
 964
 965	return NF_HOOK(NFPROTO_ARP, NF_ARP_IN,
 966		       dev_net(dev), NULL, skb, dev, NULL,
 967		       arp_process);
 968
 969consumeskb:
 970	consume_skb(skb);
 971	return NET_RX_SUCCESS;
 972freeskb:
 973	kfree_skb(skb);
 974out_of_mem:
 975	return NET_RX_DROP;
 976}
 977
 978/*
 979 *	User level interface (ioctl)
 980 */
 981
 982/*
 983 *	Set (create) an ARP cache entry.
 984 */
 985
 986static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
 987{
 988	if (!dev) {
 989		IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
 990		return 0;
 991	}
 992	if (__in_dev_get_rtnl(dev)) {
 993		IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
 994		return 0;
 995	}
 996	return -ENXIO;
 997}
 998
 999static int arp_req_set_public(struct net *net, struct arpreq *r,
1000		struct net_device *dev)
1001{
1002	__be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1003	__be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1004
1005	if (mask && mask != htonl(0xFFFFFFFF))
1006		return -EINVAL;
1007	if (!dev && (r->arp_flags & ATF_COM)) {
1008		dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family,
1009				      r->arp_ha.sa_data);
1010		if (!dev)
1011			return -ENODEV;
1012	}
1013	if (mask) {
1014		if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1))
1015			return -ENOBUFS;
1016		return 0;
1017	}
1018
1019	return arp_req_set_proxy(net, dev, 1);
1020}
1021
1022static int arp_req_set(struct net *net, struct arpreq *r,
1023		       struct net_device *dev)
1024{
1025	__be32 ip;
1026	struct neighbour *neigh;
1027	int err;
1028
1029	if (r->arp_flags & ATF_PUBL)
1030		return arp_req_set_public(net, r, dev);
1031
1032	ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1033	if (r->arp_flags & ATF_PERM)
1034		r->arp_flags |= ATF_COM;
1035	if (!dev) {
1036		struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1037
1038		if (IS_ERR(rt))
1039			return PTR_ERR(rt);
1040		dev = rt->dst.dev;
1041		ip_rt_put(rt);
1042		if (!dev)
1043			return -EINVAL;
1044	}
1045	switch (dev->type) {
1046#if IS_ENABLED(CONFIG_FDDI)
1047	case ARPHRD_FDDI:
1048		/*
1049		 * According to RFC 1390, FDDI devices should accept ARP
1050		 * hardware types of 1 (Ethernet).  However, to be more
1051		 * robust, we'll accept hardware types of either 1 (Ethernet)
1052		 * or 6 (IEEE 802.2).
1053		 */
1054		if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1055		    r->arp_ha.sa_family != ARPHRD_ETHER &&
1056		    r->arp_ha.sa_family != ARPHRD_IEEE802)
1057			return -EINVAL;
1058		break;
1059#endif
1060	default:
1061		if (r->arp_ha.sa_family != dev->type)
1062			return -EINVAL;
1063		break;
1064	}
1065
1066	neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1067	err = PTR_ERR(neigh);
1068	if (!IS_ERR(neigh)) {
1069		unsigned int state = NUD_STALE;
1070		if (r->arp_flags & ATF_PERM)
1071			state = NUD_PERMANENT;
1072		err = neigh_update(neigh, (r->arp_flags & ATF_COM) ?
1073				   r->arp_ha.sa_data : NULL, state,
1074				   NEIGH_UPDATE_F_OVERRIDE |
1075				   NEIGH_UPDATE_F_ADMIN, 0);
1076		neigh_release(neigh);
1077	}
1078	return err;
1079}
1080
1081static unsigned int arp_state_to_flags(struct neighbour *neigh)
1082{
1083	if (neigh->nud_state&NUD_PERMANENT)
1084		return ATF_PERM | ATF_COM;
1085	else if (neigh->nud_state&NUD_VALID)
1086		return ATF_COM;
1087	else
1088		return 0;
1089}
1090
1091/*
1092 *	Get an ARP cache entry.
1093 */
1094
1095static int arp_req_get(struct arpreq *r, struct net_device *dev)
1096{
1097	__be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1098	struct neighbour *neigh;
1099	int err = -ENXIO;
1100
1101	neigh = neigh_lookup(&arp_tbl, &ip, dev);
1102	if (neigh) {
1103		if (!(neigh->nud_state & NUD_NOARP)) {
1104			read_lock_bh(&neigh->lock);
1105			memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
1106			r->arp_flags = arp_state_to_flags(neigh);
1107			read_unlock_bh(&neigh->lock);
1108			r->arp_ha.sa_family = dev->type;
1109			strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1110			err = 0;
1111		}
1112		neigh_release(neigh);
1113	}
1114	return err;
1115}
1116
1117static int arp_invalidate(struct net_device *dev, __be32 ip)
1118{
1119	struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
1120	int err = -ENXIO;
1121	struct neigh_table *tbl = &arp_tbl;
1122
1123	if (neigh) {
1124		if (neigh->nud_state & ~NUD_NOARP)
1125			err = neigh_update(neigh, NULL, NUD_FAILED,
1126					   NEIGH_UPDATE_F_OVERRIDE|
1127					   NEIGH_UPDATE_F_ADMIN, 0);
1128		write_lock_bh(&tbl->lock);
1129		neigh_release(neigh);
1130		neigh_remove_one(neigh, tbl);
1131		write_unlock_bh(&tbl->lock);
1132	}
1133
1134	return err;
1135}
1136
1137static int arp_req_delete_public(struct net *net, struct arpreq *r,
1138		struct net_device *dev)
1139{
1140	__be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1141	__be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1142
1143	if (mask == htonl(0xFFFFFFFF))
1144		return pneigh_delete(&arp_tbl, net, &ip, dev);
1145
1146	if (mask)
1147		return -EINVAL;
1148
1149	return arp_req_set_proxy(net, dev, 0);
1150}
1151
1152static int arp_req_delete(struct net *net, struct arpreq *r,
1153			  struct net_device *dev)
1154{
1155	__be32 ip;
1156
1157	if (r->arp_flags & ATF_PUBL)
1158		return arp_req_delete_public(net, r, dev);
1159
1160	ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1161	if (!dev) {
1162		struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1163		if (IS_ERR(rt))
1164			return PTR_ERR(rt);
1165		dev = rt->dst.dev;
1166		ip_rt_put(rt);
1167		if (!dev)
1168			return -EINVAL;
1169	}
1170	return arp_invalidate(dev, ip);
1171}
1172
1173/*
1174 *	Handle an ARP layer I/O control request.
1175 */
1176
1177int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1178{
1179	int err;
1180	struct arpreq r;
1181	struct net_device *dev = NULL;
1182
1183	switch (cmd) {
1184	case SIOCDARP:
1185	case SIOCSARP:
1186		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1187			return -EPERM;
1188		/* fall through */
1189	case SIOCGARP:
1190		err = copy_from_user(&r, arg, sizeof(struct arpreq));
1191		if (err)
1192			return -EFAULT;
1193		break;
1194	default:
1195		return -EINVAL;
1196	}
1197
1198	if (r.arp_pa.sa_family != AF_INET)
1199		return -EPFNOSUPPORT;
1200
1201	if (!(r.arp_flags & ATF_PUBL) &&
1202	    (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1203		return -EINVAL;
1204	if (!(r.arp_flags & ATF_NETMASK))
1205		((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1206							   htonl(0xFFFFFFFFUL);
1207	rtnl_lock();
1208	if (r.arp_dev[0]) {
1209		err = -ENODEV;
1210		dev = __dev_get_by_name(net, r.arp_dev);
1211		if (!dev)
1212			goto out;
1213
1214		/* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1215		if (!r.arp_ha.sa_family)
1216			r.arp_ha.sa_family = dev->type;
1217		err = -EINVAL;
1218		if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1219			goto out;
1220	} else if (cmd == SIOCGARP) {
1221		err = -ENODEV;
1222		goto out;
1223	}
1224
1225	switch (cmd) {
1226	case SIOCDARP:
1227		err = arp_req_delete(net, &r, dev);
1228		break;
1229	case SIOCSARP:
1230		err = arp_req_set(net, &r, dev);
1231		break;
1232	case SIOCGARP:
1233		err = arp_req_get(&r, dev);
1234		break;
1235	}
1236out:
1237	rtnl_unlock();
1238	if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
1239		err = -EFAULT;
1240	return err;
1241}
1242
1243static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1244			    void *ptr)
1245{
1246	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
1247	struct netdev_notifier_change_info *change_info;
1248
1249	switch (event) {
1250	case NETDEV_CHANGEADDR:
1251		neigh_changeaddr(&arp_tbl, dev);
1252		rt_cache_flush(dev_net(dev));
1253		break;
1254	case NETDEV_CHANGE:
1255		change_info = ptr;
1256		if (change_info->flags_changed & IFF_NOARP)
1257			neigh_changeaddr(&arp_tbl, dev);
1258		break;
1259	default:
1260		break;
1261	}
1262
1263	return NOTIFY_DONE;
1264}
1265
1266static struct notifier_block arp_netdev_notifier = {
1267	.notifier_call = arp_netdev_event,
1268};
1269
1270/* Note, that it is not on notifier chain.
1271   It is necessary, that this routine was called after route cache will be
1272   flushed.
1273 */
1274void arp_ifdown(struct net_device *dev)
1275{
1276	neigh_ifdown(&arp_tbl, dev);
1277}
1278
1279
1280/*
1281 *	Called once on startup.
1282 */
1283
1284static struct packet_type arp_packet_type __read_mostly = {
1285	.type =	cpu_to_be16(ETH_P_ARP),
1286	.func =	arp_rcv,
1287};
1288
1289static int arp_proc_init(void);
1290
1291void __init arp_init(void)
1292{
1293	neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl);
1294
1295	dev_add_pack(&arp_packet_type);
1296	arp_proc_init();
1297#ifdef CONFIG_SYSCTL
1298	neigh_sysctl_register(NULL, &arp_tbl.parms, NULL);
1299#endif
1300	register_netdevice_notifier(&arp_netdev_notifier);
1301}
1302
1303#ifdef CONFIG_PROC_FS
1304#if IS_ENABLED(CONFIG_AX25)
1305
1306/* ------------------------------------------------------------------------ */
1307/*
1308 *	ax25 -> ASCII conversion
1309 */
1310static void ax2asc2(ax25_address *a, char *buf)
1311{
1312	char c, *s;
1313	int n;
1314
1315	for (n = 0, s = buf; n < 6; n++) {
1316		c = (a->ax25_call[n] >> 1) & 0x7F;
1317
1318		if (c != ' ')
1319			*s++ = c;
1320	}
1321
1322	*s++ = '-';
1323	n = (a->ax25_call[6] >> 1) & 0x0F;
1324	if (n > 9) {
1325		*s++ = '1';
1326		n -= 10;
1327	}
1328
1329	*s++ = n + '0';
1330	*s++ = '\0';
1331
1332	if (*buf == '\0' || *buf == '-') {
1333		buf[0] = '*';
1334		buf[1] = '\0';
1335	}
1336}
1337#endif /* CONFIG_AX25 */
1338
1339#define HBUFFERLEN 30
1340
1341static void arp_format_neigh_entry(struct seq_file *seq,
1342				   struct neighbour *n)
1343{
1344	char hbuffer[HBUFFERLEN];
1345	int k, j;
1346	char tbuf[16];
1347	struct net_device *dev = n->dev;
1348	int hatype = dev->type;
1349
1350	read_lock(&n->lock);
1351	/* Convert hardware address to XX:XX:XX:XX ... form. */
1352#if IS_ENABLED(CONFIG_AX25)
1353	if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1354		ax2asc2((ax25_address *)n->ha, hbuffer);
1355	else {
1356#endif
1357	for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1358		hbuffer[k++] = hex_asc_hi(n->ha[j]);
1359		hbuffer[k++] = hex_asc_lo(n->ha[j]);
1360		hbuffer[k++] = ':';
1361	}
1362	if (k != 0)
1363		--k;
1364	hbuffer[k] = 0;
1365#if IS_ENABLED(CONFIG_AX25)
1366	}
1367#endif
1368	sprintf(tbuf, "%pI4", n->primary_key);
1369	seq_printf(seq, "%-16s 0x%-10x0x%-10x%-17s     *        %s\n",
1370		   tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1371	read_unlock(&n->lock);
1372}
1373
1374static void arp_format_pneigh_entry(struct seq_file *seq,
1375				    struct pneigh_entry *n)
1376{
1377	struct net_device *dev = n->dev;
1378	int hatype = dev ? dev->type : 0;
1379	char tbuf[16];
1380
1381	sprintf(tbuf, "%pI4", n->key);
1382	seq_printf(seq, "%-16s 0x%-10x0x%-10x%s     *        %s\n",
1383		   tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1384		   dev ? dev->name : "*");
1385}
1386
1387static int arp_seq_show(struct seq_file *seq, void *v)
1388{
1389	if (v == SEQ_START_TOKEN) {
1390		seq_puts(seq, "IP address       HW type     Flags       "
1391			      "HW address            Mask     Device\n");
1392	} else {
1393		struct neigh_seq_state *state = seq->private;
1394
1395		if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1396			arp_format_pneigh_entry(seq, v);
1397		else
1398			arp_format_neigh_entry(seq, v);
1399	}
1400
1401	return 0;
1402}
1403
1404static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1405{
1406	/* Don't want to confuse "arp -a" w/ magic entries,
1407	 * so we tell the generic iterator to skip NUD_NOARP.
1408	 */
1409	return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1410}
1411
1412/* ------------------------------------------------------------------------ */
1413
1414static const struct seq_operations arp_seq_ops = {
1415	.start	= arp_seq_start,
1416	.next	= neigh_seq_next,
1417	.stop	= neigh_seq_stop,
1418	.show	= arp_seq_show,
1419};
1420
1421static int arp_seq_open(struct inode *inode, struct file *file)
1422{
1423	return seq_open_net(inode, file, &arp_seq_ops,
1424			    sizeof(struct neigh_seq_state));
1425}
1426
1427static const struct file_operations arp_seq_fops = {
1428	.open           = arp_seq_open,
1429	.read           = seq_read,
1430	.llseek         = seq_lseek,
1431	.release	= seq_release_net,
1432};
1433
1434
1435static int __net_init arp_net_init(struct net *net)
1436{
1437	if (!proc_create("arp", 0444, net->proc_net, &arp_seq_fops))
1438		return -ENOMEM;
1439	return 0;
1440}
1441
1442static void __net_exit arp_net_exit(struct net *net)
1443{
1444	remove_proc_entry("arp", net->proc_net);
1445}
1446
1447static struct pernet_operations arp_net_ops = {
1448	.init = arp_net_init,
1449	.exit = arp_net_exit,
1450};
1451
1452static int __init arp_proc_init(void)
1453{
1454	return register_pernet_subsys(&arp_net_ops);
1455}
1456
1457#else /* CONFIG_PROC_FS */
1458
1459static int __init arp_proc_init(void)
1460{
1461	return 0;
1462}
1463
1464#endif /* CONFIG_PROC_FS */