1 /* linux/net/ipv4/arp.c
3 * Version: $Id: arp.c,v 1.99 2001/08/30 22:55:42 davem Exp $
5 * Copyright (C) 1994 by Florian La Roche
7 * This module implements the Address Resolution Protocol ARP (RFC 826),
8 * which is used to convert IP addresses (or in the future maybe other
9 * high-level addresses) into a low-level hardware address (like an Ethernet
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version
15 * 2 of the License, or (at your option) any later version.
18 * Alan Cox : Removed the Ethernet assumptions in
20 * Alan Cox : Fixed some small errors in the ARP
22 * Alan Cox : Allow >4K in /proc
23 * Alan Cox : Make ARP add its own protocol entry
24 * Ross Martin : Rewrote arp_rcv() and arp_get_info()
25 * Stephen Henson : Add AX25 support to arp_get_info()
26 * Alan Cox : Drop data when a device is downed.
27 * Alan Cox : Use init_timer().
28 * Alan Cox : Double lock fixes.
29 * Martin Seine : Move the arphdr structure
30 * to if_arp.h for compatibility.
31 * with BSD based programs.
32 * Andrew Tridgell : Added ARP netmask code and
33 * re-arranged proxy handling.
34 * Alan Cox : Changed to use notifiers.
35 * Niibe Yutaka : Reply for this device or proxies only.
36 * Alan Cox : Don't proxy across hardware types!
37 * Jonathan Naylor : Added support for NET/ROM.
38 * Mike Shaver : RFC1122 checks.
39 * Jonathan Naylor : Only lookup the hardware address for
40 * the correct hardware type.
41 * Germano Caronni : Assorted subtle races.
42 * Craig Schlenter : Don't modify permanent entry
44 * Russ Nelson : Tidied up a few bits.
45 * Alexey Kuznetsov: Major changes to caching and behaviour,
46 * eg intelligent arp probing and
48 * of host down events.
49 * Alan Cox : Missing unlock in device events.
50 * Eckes : ARP ioctl control errors.
51 * Alexey Kuznetsov: Arp free fix.
52 * Manuel Rodriguez: Gratuitous ARP.
53 * Jonathan Layes : Added arpd support through kerneld
54 * message queue (960314)
55 * Mike Shaver : /proc/sys/net/ipv4/arp_* support
56 * Mike McLagan : Routing by source
57 * Stuart Cheshire : Metricom and grat arp fixes
58 * *** FOR 2.1 clean this up ***
59 * Lawrence V. Stefani: (08/12/96) Added FDDI support.
60 * Alan Cox : Took the AP1000 nasty FDDI hack and
61 * folded into the mainstream FDDI code.
62 * Ack spit, Linus how did you allow that
64 * Jes Sorensen : Make FDDI work again in 2.1.x and
65 * clean up the APFDDI & gen. FDDI bits.
66 * Alexey Kuznetsov: new arp state machine;
67 * now it is in net/core/neighbour.c.
68 * Krzysztof Halasa: Added Frame Relay ARP support.
69 * Arnaldo C. Melo : convert /proc/net/arp to seq_file
70 * Shmulik Hen: Split arp_send to arp_create and
71 * arp_xmit so intermediate drivers like
72 * bonding can change the skb before
73 * sending (e.g. insert 8021q tag).
74 * Harald Welte : convert to make use of jenkins hash
77 #include <linux/module.h>
78 #include <linux/types.h>
79 #include <linux/string.h>
80 #include <linux/kernel.h>
81 #include <linux/sched.h>
82 #include <linux/capability.h>
83 #include <linux/socket.h>
84 #include <linux/sockios.h>
85 #include <linux/errno.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/trdevice.h>
95 #include <linux/skbuff.h>
96 #include <linux/proc_fs.h>
97 #include <linux/seq_file.h>
98 #include <linux/stat.h>
99 #include <linux/init.h>
100 #include <linux/net.h>
101 #include <linux/rcupdate.h>
102 #include <linux/jhash.h>
104 #include <linux/sysctl.h>
108 #include <net/icmp.h>
109 #include <net/route.h>
110 #include <net/protocol.h>
112 #include <net/sock.h>
114 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
115 #include <net/ax25.h>
116 #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
117 #include <net/netrom.h>
120 #if defined(CONFIG_ATM_CLIP) || defined(CONFIG_ATM_CLIP_MODULE)
121 #include <net/atmclip.h>
122 struct neigh_table *clip_tbl_hook;
125 #include <asm/system.h>
126 #include <asm/uaccess.h>
128 #include <linux/netfilter_arp.h>
131 * Interface to generic neighbour cache.
133 static u32 arp_hash(const void *pkey, const struct net_device *dev);
134 static int arp_constructor(struct neighbour *neigh);
135 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
136 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
137 static void parp_redo(struct sk_buff *skb);
139 static struct neigh_ops arp_generic_ops = {
141 .solicit = arp_solicit,
142 .error_report = arp_error_report,
143 .output = neigh_resolve_output,
144 .connected_output = neigh_connected_output,
145 .hh_output = dev_queue_xmit,
146 .queue_xmit = dev_queue_xmit,
149 static struct neigh_ops arp_hh_ops = {
151 .solicit = arp_solicit,
152 .error_report = arp_error_report,
153 .output = neigh_resolve_output,
154 .connected_output = neigh_resolve_output,
155 .hh_output = dev_queue_xmit,
156 .queue_xmit = dev_queue_xmit,
159 static struct neigh_ops arp_direct_ops = {
161 .output = dev_queue_xmit,
162 .connected_output = dev_queue_xmit,
163 .hh_output = dev_queue_xmit,
164 .queue_xmit = dev_queue_xmit,
167 struct neigh_ops arp_broken_ops = {
169 .solicit = arp_solicit,
170 .error_report = arp_error_report,
171 .output = neigh_compat_output,
172 .connected_output = neigh_compat_output,
173 .hh_output = dev_queue_xmit,
174 .queue_xmit = dev_queue_xmit,
177 struct neigh_table arp_tbl = {
179 .entry_size = sizeof(struct neighbour) + 4,
182 .constructor = arp_constructor,
183 .proxy_redo = parp_redo,
187 .base_reachable_time = 30 * HZ,
188 .retrans_time = 1 * HZ,
189 .gc_staletime = 60 * HZ,
190 .reachable_time = 30 * HZ,
191 .delay_probe_time = 5 * HZ,
195 .anycast_delay = 1 * HZ,
196 .proxy_delay = (8 * HZ) / 10,
200 .gc_interval = 30 * HZ,
206 int arp_mc_map(u32 addr, u8 *haddr, struct net_device *dev, int dir)
212 ip_eth_mc_map(addr, haddr);
214 case ARPHRD_IEEE802_TR:
215 ip_tr_mc_map(addr, haddr);
217 case ARPHRD_INFINIBAND:
218 ip_ib_mc_map(addr, haddr);
222 memcpy(haddr, dev->broadcast, dev->addr_len);
230 static u32 arp_hash(const void *pkey, const struct net_device *dev)
232 return jhash_2words(*(u32 *)pkey, dev->ifindex, arp_tbl.hash_rnd);
235 static int arp_constructor(struct neighbour *neigh)
237 __be32 addr = *(__be32*)neigh->primary_key;
238 struct net_device *dev = neigh->dev;
239 struct in_device *in_dev;
240 struct neigh_parms *parms;
242 neigh->type = inet_addr_type(addr);
245 in_dev = __in_dev_get_rcu(dev);
246 if (in_dev == NULL) {
251 parms = in_dev->arp_parms;
252 __neigh_parms_put(neigh->parms);
253 neigh->parms = neigh_parms_clone(parms);
256 if (dev->hard_header == NULL) {
257 neigh->nud_state = NUD_NOARP;
258 neigh->ops = &arp_direct_ops;
259 neigh->output = neigh->ops->queue_xmit;
261 /* Good devices (checked by reading texts, but only Ethernet is
264 ARPHRD_ETHER: (ethernet, apfddi)
267 ARPHRD_METRICOM: (strip)
271 ARPHRD_IPDDP will also work, if author repairs it.
272 I did not it, because this driver does not work even
277 /* So... these "amateur" devices are hopeless.
278 The only thing, that I can say now:
279 It is very sad that we need to keep ugly obsolete
280 code to make them happy.
282 They should be moved to more reasonable state, now
283 they use rebuild_header INSTEAD OF hard_start_xmit!!!
284 Besides that, they are sort of out of date
285 (a lot of redundant clones/copies, useless in 2.1),
286 I wonder why people believe that they work.
292 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
294 #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
297 neigh->ops = &arp_broken_ops;
298 neigh->output = neigh->ops->output;
303 if (neigh->type == RTN_MULTICAST) {
304 neigh->nud_state = NUD_NOARP;
305 arp_mc_map(addr, neigh->ha, dev, 1);
306 } else if (dev->flags&(IFF_NOARP|IFF_LOOPBACK)) {
307 neigh->nud_state = NUD_NOARP;
308 memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
309 } else if (neigh->type == RTN_BROADCAST || dev->flags&IFF_POINTOPOINT) {
310 neigh->nud_state = NUD_NOARP;
311 memcpy(neigh->ha, dev->broadcast, dev->addr_len);
313 if (dev->hard_header_cache)
314 neigh->ops = &arp_hh_ops;
316 neigh->ops = &arp_generic_ops;
317 if (neigh->nud_state&NUD_VALID)
318 neigh->output = neigh->ops->connected_output;
320 neigh->output = neigh->ops->output;
325 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
327 dst_link_failure(skb);
331 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
335 struct net_device *dev = neigh->dev;
336 __be32 target = *(__be32*)neigh->primary_key;
337 int probes = atomic_read(&neigh->probes);
338 struct in_device *in_dev = in_dev_get(dev);
343 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
345 case 0: /* By default announce any local IP */
346 if (skb && inet_addr_type(skb->nh.iph->saddr) == RTN_LOCAL)
347 saddr = skb->nh.iph->saddr;
349 case 1: /* Restrict announcements of saddr in same subnet */
352 saddr = skb->nh.iph->saddr;
353 if (inet_addr_type(saddr) == RTN_LOCAL) {
354 /* saddr should be known to target */
355 if (inet_addr_onlink(in_dev, target, saddr))
360 case 2: /* Avoid secondary IPs, get a primary/preferred one */
367 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
369 if ((probes -= neigh->parms->ucast_probes) < 0) {
370 if (!(neigh->nud_state&NUD_VALID))
371 printk(KERN_DEBUG "trying to ucast probe in NUD_INVALID\n");
373 read_lock_bh(&neigh->lock);
374 } else if ((probes -= neigh->parms->app_probes) < 0) {
381 arp_send(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
382 dst_ha, dev->dev_addr, NULL);
384 read_unlock_bh(&neigh->lock);
387 static int arp_ignore(struct in_device *in_dev, struct net_device *dev,
388 __be32 sip, __be32 tip)
392 switch (IN_DEV_ARP_IGNORE(in_dev)) {
393 case 0: /* Reply, the tip is already validated */
395 case 1: /* Reply only if tip is configured on the incoming interface */
397 scope = RT_SCOPE_HOST;
400 * Reply only if tip is configured on the incoming interface
401 * and is in same subnet as sip
403 scope = RT_SCOPE_HOST;
405 case 3: /* Do not reply for scope host addresses */
407 scope = RT_SCOPE_LINK;
410 case 4: /* Reserved */
415 case 8: /* Do not reply */
420 return !inet_confirm_addr(dev, sip, tip, scope);
423 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
425 struct flowi fl = { .nl_u = { .ip4_u = { .daddr = sip,
429 /*unsigned long now; */
431 if (ip_route_output_key(&rt, &fl) < 0)
433 if (rt->u.dst.dev != dev) {
434 NET_INC_STATS_BH(LINUX_MIB_ARPFILTER);
441 /* OBSOLETE FUNCTIONS */
444 * Find an arp mapping in the cache. If not found, post a request.
446 * It is very UGLY routine: it DOES NOT use skb->dst->neighbour,
447 * even if it exists. It is supposed that skb->dev was mangled
448 * by a virtual device (eql, shaper). Nobody but broken devices
449 * is allowed to use this function, it is scheduled to be removed. --ANK
452 static int arp_set_predefined(int addr_hint, unsigned char * haddr, __be32 paddr, struct net_device * dev)
456 printk(KERN_DEBUG "ARP: arp called for own IP address\n");
457 memcpy(haddr, dev->dev_addr, dev->addr_len);
460 arp_mc_map(paddr, haddr, dev, 1);
463 memcpy(haddr, dev->broadcast, dev->addr_len);
470 int arp_find(unsigned char *haddr, struct sk_buff *skb)
472 struct net_device *dev = skb->dev;
477 printk(KERN_DEBUG "arp_find is called with dst==NULL\n");
482 paddr = ((struct rtable*)skb->dst)->rt_gateway;
484 if (arp_set_predefined(inet_addr_type(paddr), haddr, paddr, dev))
487 n = __neigh_lookup(&arp_tbl, &paddr, dev, 1);
491 if (n->nud_state&NUD_VALID || neigh_event_send(n, skb) == 0) {
492 read_lock_bh(&n->lock);
493 memcpy(haddr, n->ha, dev->addr_len);
494 read_unlock_bh(&n->lock);
504 /* END OF OBSOLETE FUNCTIONS */
506 int arp_bind_neighbour(struct dst_entry *dst)
508 struct net_device *dev = dst->dev;
509 struct neighbour *n = dst->neighbour;
514 __be32 nexthop = ((struct rtable*)dst)->rt_gateway;
515 if (dev->flags&(IFF_LOOPBACK|IFF_POINTOPOINT))
517 n = __neigh_lookup_errno(
518 #if defined(CONFIG_ATM_CLIP) || defined(CONFIG_ATM_CLIP_MODULE)
519 dev->type == ARPHRD_ATM ? clip_tbl_hook :
521 &arp_tbl, &nexthop, dev);
530 * Check if we can use proxy ARP for this path
533 static inline int arp_fwd_proxy(struct in_device *in_dev, struct rtable *rt)
535 struct in_device *out_dev;
538 if (!IN_DEV_PROXY_ARP(in_dev))
541 if ((imi = IN_DEV_MEDIUM_ID(in_dev)) == 0)
546 /* place to check for proxy_arp for routes */
548 if ((out_dev = in_dev_get(rt->u.dst.dev)) != NULL) {
549 omi = IN_DEV_MEDIUM_ID(out_dev);
552 return (omi != imi && omi != -1);
556 * Interface to link layer: send routine and receive handler.
560 * Create an arp packet. If (dest_hw == NULL), we create a broadcast
563 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
564 struct net_device *dev, __be32 src_ip,
565 unsigned char *dest_hw, unsigned char *src_hw,
566 unsigned char *target_hw)
570 unsigned char *arp_ptr;
576 skb = alloc_skb(sizeof(struct arphdr)+ 2*(dev->addr_len+4)
577 + LL_RESERVED_SPACE(dev), GFP_ATOMIC);
581 skb_reserve(skb, LL_RESERVED_SPACE(dev));
582 skb->nh.raw = skb->data;
583 arp = (struct arphdr *) skb_put(skb,sizeof(struct arphdr) + 2*(dev->addr_len+4));
585 skb->protocol = htons(ETH_P_ARP);
587 src_hw = dev->dev_addr;
589 dest_hw = dev->broadcast;
592 * Fill the device header for the ARP frame
594 if (dev->hard_header &&
595 dev->hard_header(skb,dev,ptype,dest_hw,src_hw,skb->len) < 0)
599 * Fill out the arp protocol part.
601 * The arp hardware type should match the device type, except for FDDI,
602 * which (according to RFC 1390) should always equal 1 (Ethernet).
605 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
606 * DIX code for the protocol. Make these device structure fields.
610 arp->ar_hrd = htons(dev->type);
611 arp->ar_pro = htons(ETH_P_IP);
614 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
616 arp->ar_hrd = htons(ARPHRD_AX25);
617 arp->ar_pro = htons(AX25_P_IP);
620 #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
622 arp->ar_hrd = htons(ARPHRD_NETROM);
623 arp->ar_pro = htons(AX25_P_IP);
630 arp->ar_hrd = htons(ARPHRD_ETHER);
631 arp->ar_pro = htons(ETH_P_IP);
635 case ARPHRD_IEEE802_TR:
636 arp->ar_hrd = htons(ARPHRD_IEEE802);
637 arp->ar_pro = htons(ETH_P_IP);
642 arp->ar_hln = dev->addr_len;
644 arp->ar_op = htons(type);
646 arp_ptr=(unsigned char *)(arp+1);
648 memcpy(arp_ptr, src_hw, dev->addr_len);
649 arp_ptr+=dev->addr_len;
650 memcpy(arp_ptr, &src_ip,4);
652 if (target_hw != NULL)
653 memcpy(arp_ptr, target_hw, dev->addr_len);
655 memset(arp_ptr, 0, dev->addr_len);
656 arp_ptr+=dev->addr_len;
657 memcpy(arp_ptr, &dest_ip, 4);
667 * Send an arp packet.
669 void arp_xmit(struct sk_buff *skb)
671 /* Send it off, maybe filter it using firewalling first. */
672 NF_HOOK(NF_ARP, NF_ARP_OUT, skb, NULL, skb->dev, dev_queue_xmit);
676 * Create and send an arp packet.
678 void arp_send(int type, int ptype, __be32 dest_ip,
679 struct net_device *dev, __be32 src_ip,
680 unsigned char *dest_hw, unsigned char *src_hw,
681 unsigned char *target_hw)
686 * No arp on this interface.
689 if (dev->flags&IFF_NOARP)
692 skb = arp_create(type, ptype, dest_ip, dev, src_ip,
693 dest_hw, src_hw, target_hw);
702 * Process an arp request.
705 static int arp_process(struct sk_buff *skb)
707 struct net_device *dev = skb->dev;
708 struct in_device *in_dev = in_dev_get(dev);
710 unsigned char *arp_ptr;
712 unsigned char *sha, *tha;
714 u16 dev_type = dev->type;
718 /* arp_rcv below verifies the ARP header and verifies the device
729 if (arp->ar_pro != htons(ETH_P_IP) ||
730 htons(dev_type) != arp->ar_hrd)
733 #ifdef CONFIG_NET_ETHERNET
737 case ARPHRD_IEEE802_TR:
745 #if defined(CONFIG_NET_ETHERNET) || defined(CONFIG_TR) || \
746 defined(CONFIG_FDDI) || defined(CONFIG_NET_FC)
748 * ETHERNET, Token Ring and Fibre Channel (which are IEEE 802
749 * devices, according to RFC 2625) devices will accept ARP
750 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
751 * This is the case also of FDDI, where the RFC 1390 says that
752 * FDDI devices should accept ARP hardware of (1) Ethernet,
753 * however, to be more robust, we'll accept both 1 (Ethernet)
756 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
757 arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
758 arp->ar_pro != htons(ETH_P_IP))
762 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
764 if (arp->ar_pro != htons(AX25_P_IP) ||
765 arp->ar_hrd != htons(ARPHRD_AX25))
768 #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
770 if (arp->ar_pro != htons(AX25_P_IP) ||
771 arp->ar_hrd != htons(ARPHRD_NETROM))
778 /* Understand only these message types */
780 if (arp->ar_op != htons(ARPOP_REPLY) &&
781 arp->ar_op != htons(ARPOP_REQUEST))
787 arp_ptr= (unsigned char *)(arp+1);
789 arp_ptr += dev->addr_len;
790 memcpy(&sip, arp_ptr, 4);
793 arp_ptr += dev->addr_len;
794 memcpy(&tip, arp_ptr, 4);
796 * Check for bad requests for 127.x.x.x and requests for multicast
797 * addresses. If this is one such, delete it.
799 if (LOOPBACK(tip) || MULTICAST(tip))
803 * Special case: We must set Frame Relay source Q.922 address
805 if (dev_type == ARPHRD_DLCI)
806 sha = dev->broadcast;
809 * Process entry. The idea here is we want to send a reply if it is a
810 * request for us or if it is a request for someone else that we hold
811 * a proxy for. We want to add an entry to our cache if it is a reply
812 * to us or if it is a request for our address.
813 * (The assumption for this last is that if someone is requesting our
814 * address, they are probably intending to talk to us, so it saves time
815 * if we cache their address. Their address is also probably not in
816 * our cache, since ours is not in their cache.)
818 * Putting this another way, we only care about replies if they are to
819 * us, in which case we add them to the cache. For requests, we care
820 * about those for us and those for our proxies. We reply to both,
821 * and in the case of requests for us we add the requester to the arp
825 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
827 if (arp->ar_op == htons(ARPOP_REQUEST) &&
828 inet_addr_type(tip) == RTN_LOCAL &&
829 !arp_ignore(in_dev,dev,sip,tip))
830 arp_send(ARPOP_REPLY,ETH_P_ARP,tip,dev,tip,sha,dev->dev_addr,dev->dev_addr);
834 if (arp->ar_op == htons(ARPOP_REQUEST) &&
835 ip_route_input(skb, tip, sip, 0, dev) == 0) {
837 rt = (struct rtable*)skb->dst;
838 addr_type = rt->rt_type;
840 if (addr_type == RTN_LOCAL) {
841 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
846 dont_send |= arp_ignore(in_dev,dev,sip,tip);
847 if (!dont_send && IN_DEV_ARPFILTER(in_dev))
848 dont_send |= arp_filter(sip,tip,dev);
850 arp_send(ARPOP_REPLY,ETH_P_ARP,sip,dev,tip,sha,dev->dev_addr,sha);
855 } else if (IN_DEV_FORWARD(in_dev)) {
856 if ((rt->rt_flags&RTCF_DNAT) ||
857 (addr_type == RTN_UNICAST && rt->u.dst.dev != dev &&
858 (arp_fwd_proxy(in_dev, rt) || pneigh_lookup(&arp_tbl, &tip, dev, 0)))) {
859 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
863 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
864 skb->pkt_type == PACKET_HOST ||
865 in_dev->arp_parms->proxy_delay == 0) {
866 arp_send(ARPOP_REPLY,ETH_P_ARP,sip,dev,tip,sha,dev->dev_addr,sha);
868 pneigh_enqueue(&arp_tbl, in_dev->arp_parms, skb);
877 /* Update our ARP tables */
879 n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
881 if (ipv4_devconf.arp_accept) {
882 /* Unsolicited ARP is not accepted by default.
883 It is possible, that this option should be enabled for some
884 devices (strip is candidate)
887 arp->ar_op == htons(ARPOP_REPLY) &&
888 inet_addr_type(sip) == RTN_UNICAST)
889 n = __neigh_lookup(&arp_tbl, &sip, dev, -1);
893 int state = NUD_REACHABLE;
896 /* If several different ARP replies follows back-to-back,
897 use the FIRST one. It is possible, if several proxy
898 agents are active. Taking the first reply prevents
899 arp trashing and chooses the fastest router.
901 override = time_after(jiffies, n->updated + n->parms->locktime);
903 /* Broadcast replies and request packets
904 do not assert neighbour reachability.
906 if (arp->ar_op != htons(ARPOP_REPLY) ||
907 skb->pkt_type != PACKET_HOST)
909 neigh_update(n, sha, state, override ? NEIGH_UPDATE_F_OVERRIDE : 0);
920 static void parp_redo(struct sk_buff *skb)
927 * Receive an arp request from the device layer.
930 static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
931 struct packet_type *pt, struct net_device *orig_dev)
935 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
936 if (!pskb_may_pull(skb, (sizeof(struct arphdr) +
937 (2 * dev->addr_len) +
942 if (arp->ar_hln != dev->addr_len ||
943 dev->flags & IFF_NOARP ||
944 skb->pkt_type == PACKET_OTHERHOST ||
945 skb->pkt_type == PACKET_LOOPBACK ||
949 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
952 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
954 return NF_HOOK(NF_ARP, NF_ARP_IN, skb, dev, NULL, arp_process);
963 * User level interface (ioctl)
967 * Set (create) an ARP cache entry.
970 static int arp_req_set(struct arpreq *r, struct net_device * dev)
972 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
973 struct neighbour *neigh;
976 if (r->arp_flags&ATF_PUBL) {
977 __be32 mask = ((struct sockaddr_in *) &r->arp_netmask)->sin_addr.s_addr;
978 if (mask && mask != htonl(0xFFFFFFFF))
980 if (!dev && (r->arp_flags & ATF_COM)) {
981 dev = dev_getbyhwaddr(r->arp_ha.sa_family, r->arp_ha.sa_data);
986 if (pneigh_lookup(&arp_tbl, &ip, dev, 1) == NULL)
991 ipv4_devconf.proxy_arp = 1;
994 if (__in_dev_get_rtnl(dev)) {
995 __in_dev_get_rtnl(dev)->cnf.proxy_arp = 1;
1001 if (r->arp_flags & ATF_PERM)
1002 r->arp_flags |= ATF_COM;
1004 struct flowi fl = { .nl_u = { .ip4_u = { .daddr = ip,
1005 .tos = RTO_ONLINK } } };
1007 if ((err = ip_route_output_key(&rt, &fl)) != 0)
1009 dev = rt->u.dst.dev;
1014 switch (dev->type) {
1018 * According to RFC 1390, FDDI devices should accept ARP
1019 * hardware types of 1 (Ethernet). However, to be more
1020 * robust, we'll accept hardware types of either 1 (Ethernet)
1021 * or 6 (IEEE 802.2).
1023 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1024 r->arp_ha.sa_family != ARPHRD_ETHER &&
1025 r->arp_ha.sa_family != ARPHRD_IEEE802)
1030 if (r->arp_ha.sa_family != dev->type)
1035 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1036 err = PTR_ERR(neigh);
1037 if (!IS_ERR(neigh)) {
1038 unsigned state = NUD_STALE;
1039 if (r->arp_flags & ATF_PERM)
1040 state = NUD_PERMANENT;
1041 err = neigh_update(neigh, (r->arp_flags&ATF_COM) ?
1042 r->arp_ha.sa_data : NULL, state,
1043 NEIGH_UPDATE_F_OVERRIDE|
1044 NEIGH_UPDATE_F_ADMIN);
1045 neigh_release(neigh);
1050 static unsigned arp_state_to_flags(struct neighbour *neigh)
1053 if (neigh->nud_state&NUD_PERMANENT)
1054 flags = ATF_PERM|ATF_COM;
1055 else if (neigh->nud_state&NUD_VALID)
1061 * Get an ARP cache entry.
1064 static int arp_req_get(struct arpreq *r, struct net_device *dev)
1066 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1067 struct neighbour *neigh;
1070 neigh = neigh_lookup(&arp_tbl, &ip, dev);
1072 read_lock_bh(&neigh->lock);
1073 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
1074 r->arp_flags = arp_state_to_flags(neigh);
1075 read_unlock_bh(&neigh->lock);
1076 r->arp_ha.sa_family = dev->type;
1077 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1078 neigh_release(neigh);
1084 static int arp_req_delete(struct arpreq *r, struct net_device * dev)
1087 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1088 struct neighbour *neigh;
1090 if (r->arp_flags & ATF_PUBL) {
1092 ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1093 if (mask == htonl(0xFFFFFFFF))
1094 return pneigh_delete(&arp_tbl, &ip, dev);
1097 ipv4_devconf.proxy_arp = 0;
1100 if (__in_dev_get_rtnl(dev)) {
1101 __in_dev_get_rtnl(dev)->cnf.proxy_arp = 0;
1110 struct flowi fl = { .nl_u = { .ip4_u = { .daddr = ip,
1111 .tos = RTO_ONLINK } } };
1113 if ((err = ip_route_output_key(&rt, &fl)) != 0)
1115 dev = rt->u.dst.dev;
1121 neigh = neigh_lookup(&arp_tbl, &ip, dev);
1123 if (neigh->nud_state&~NUD_NOARP)
1124 err = neigh_update(neigh, NULL, NUD_FAILED,
1125 NEIGH_UPDATE_F_OVERRIDE|
1126 NEIGH_UPDATE_F_ADMIN);
1127 neigh_release(neigh);
1133 * Handle an ARP layer I/O control request.
1136 int arp_ioctl(unsigned int cmd, void __user *arg)
1140 struct net_device *dev = NULL;
1145 if (!capable(CAP_NET_ADMIN))
1148 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1156 if (r.arp_pa.sa_family != AF_INET)
1157 return -EPFNOSUPPORT;
1159 if (!(r.arp_flags & ATF_PUBL) &&
1160 (r.arp_flags & (ATF_NETMASK|ATF_DONTPUB)))
1162 if (!(r.arp_flags & ATF_NETMASK))
1163 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1164 htonl(0xFFFFFFFFUL);
1168 if ((dev = __dev_get_by_name(r.arp_dev)) == NULL)
1171 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1172 if (!r.arp_ha.sa_family)
1173 r.arp_ha.sa_family = dev->type;
1175 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1177 } else if (cmd == SIOCGARP) {
1184 err = arp_req_delete(&r, dev);
1187 err = arp_req_set(&r, dev);
1190 err = arp_req_get(&r, dev);
1191 if (!err && copy_to_user(arg, &r, sizeof(r)))
1200 static int arp_netdev_event(struct notifier_block *this, unsigned long event, void *ptr)
1202 struct net_device *dev = ptr;
1205 case NETDEV_CHANGEADDR:
1206 neigh_changeaddr(&arp_tbl, dev);
1216 static struct notifier_block arp_netdev_notifier = {
1217 .notifier_call = arp_netdev_event,
1220 /* Note, that it is not on notifier chain.
1221 It is necessary, that this routine was called after route cache will be
1224 void arp_ifdown(struct net_device *dev)
1226 neigh_ifdown(&arp_tbl, dev);
1231 * Called once on startup.
1234 static struct packet_type arp_packet_type = {
1235 .type = __constant_htons(ETH_P_ARP),
1239 static int arp_proc_init(void);
1241 void __init arp_init(void)
1243 neigh_table_init(&arp_tbl);
1245 dev_add_pack(&arp_packet_type);
1247 #ifdef CONFIG_SYSCTL
1248 neigh_sysctl_register(NULL, &arp_tbl.parms, NET_IPV4,
1249 NET_IPV4_NEIGH, "ipv4", NULL, NULL);
1251 register_netdevice_notifier(&arp_netdev_notifier);
1254 #ifdef CONFIG_PROC_FS
1255 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1257 /* ------------------------------------------------------------------------ */
1259 * ax25 -> ASCII conversion
1261 static char *ax2asc2(ax25_address *a, char *buf)
1266 for (n = 0, s = buf; n < 6; n++) {
1267 c = (a->ax25_call[n] >> 1) & 0x7F;
1269 if (c != ' ') *s++ = c;
1274 if ((n = ((a->ax25_call[6] >> 1) & 0x0F)) > 9) {
1282 if (*buf == '\0' || *buf == '-')
1288 #endif /* CONFIG_AX25 */
1290 #define HBUFFERLEN 30
1292 static void arp_format_neigh_entry(struct seq_file *seq,
1293 struct neighbour *n)
1295 char hbuffer[HBUFFERLEN];
1296 const char hexbuf[] = "0123456789ABCDEF";
1299 struct net_device *dev = n->dev;
1300 int hatype = dev->type;
1302 read_lock(&n->lock);
1303 /* Convert hardware address to XX:XX:XX:XX ... form. */
1304 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1305 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1306 ax2asc2((ax25_address *)n->ha, hbuffer);
1309 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1310 hbuffer[k++] = hexbuf[(n->ha[j] >> 4) & 15];
1311 hbuffer[k++] = hexbuf[n->ha[j] & 15];
1315 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1318 sprintf(tbuf, "%u.%u.%u.%u", NIPQUAD(*(u32*)n->primary_key));
1319 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1320 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1321 read_unlock(&n->lock);
1324 static void arp_format_pneigh_entry(struct seq_file *seq,
1325 struct pneigh_entry *n)
1327 struct net_device *dev = n->dev;
1328 int hatype = dev ? dev->type : 0;
1331 sprintf(tbuf, "%u.%u.%u.%u", NIPQUAD(*(u32*)n->key));
1332 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1333 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1334 dev ? dev->name : "*");
1337 static int arp_seq_show(struct seq_file *seq, void *v)
1339 if (v == SEQ_START_TOKEN) {
1340 seq_puts(seq, "IP address HW type Flags "
1341 "HW address Mask Device\n");
1343 struct neigh_seq_state *state = seq->private;
1345 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1346 arp_format_pneigh_entry(seq, v);
1348 arp_format_neigh_entry(seq, v);
1354 static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1356 /* Don't want to confuse "arp -a" w/ magic entries,
1357 * so we tell the generic iterator to skip NUD_NOARP.
1359 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1362 /* ------------------------------------------------------------------------ */
1364 static struct seq_operations arp_seq_ops = {
1365 .start = arp_seq_start,
1366 .next = neigh_seq_next,
1367 .stop = neigh_seq_stop,
1368 .show = arp_seq_show,
1371 static int arp_seq_open(struct inode *inode, struct file *file)
1373 struct seq_file *seq;
1375 struct neigh_seq_state *s = kzalloc(sizeof(*s), GFP_KERNEL);
1380 rc = seq_open(file, &arp_seq_ops);
1384 seq = file->private_data;
1393 static struct file_operations arp_seq_fops = {
1394 .owner = THIS_MODULE,
1395 .open = arp_seq_open,
1397 .llseek = seq_lseek,
1398 .release = seq_release_private,
1401 static int __init arp_proc_init(void)
1403 if (!proc_net_fops_create("arp", S_IRUGO, &arp_seq_fops))
1408 #else /* CONFIG_PROC_FS */
1410 static int __init arp_proc_init(void)
1415 #endif /* CONFIG_PROC_FS */
1417 EXPORT_SYMBOL(arp_broken_ops);
1418 EXPORT_SYMBOL(arp_find);
1419 EXPORT_SYMBOL(arp_create);
1420 EXPORT_SYMBOL(arp_xmit);
1421 EXPORT_SYMBOL(arp_send);
1422 EXPORT_SYMBOL(arp_tbl);
1424 #if defined(CONFIG_ATM_CLIP) || defined(CONFIG_ATM_CLIP_MODULE)
1425 EXPORT_SYMBOL(clip_tbl_hook);