1 /* linux/net/inet/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 * Shmulik Hen: Split arp_send to arp_create and
70 * arp_xmit so intermediate drivers like
71 * bonding can change the skb before
72 * sending (e.g. insert 8021q tag).
73 * Harald Welte : convert to make use of jenkins hash
76 #include <linux/types.h>
77 #include <linux/string.h>
78 #include <linux/kernel.h>
79 #include <linux/module.h>
80 #include <linux/sched.h>
81 #include <linux/config.h>
82 #include <linux/socket.h>
83 #include <linux/sockios.h>
84 #include <linux/errno.h>
87 #include <linux/inet.h>
88 #include <linux/netdevice.h>
89 #include <linux/etherdevice.h>
90 #include <linux/fddidevice.h>
91 #include <linux/if_arp.h>
92 #include <linux/trdevice.h>
93 #include <linux/skbuff.h>
94 #include <linux/proc_fs.h>
95 #include <linux/stat.h>
96 #include <linux/init.h>
97 #include <linux/jhash.h>
98 #include <linux/module.h>
100 #include <linux/sysctl.h>
104 #include <net/icmp.h>
105 #include <net/route.h>
106 #include <net/protocol.h>
108 #include <net/sock.h>
110 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
111 #include <net/ax25.h>
112 #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
113 #include <net/netrom.h>
116 #if defined(CONFIG_ATM_CLIP) || defined(CONFIG_ATM_CLIP_MODULE)
117 #include <net/atmclip.h>
118 struct neigh_table *clip_tbl_hook;
121 #include <asm/system.h>
122 #include <asm/uaccess.h>
124 #include <linux/netfilter_arp.h>
127 * Interface to generic neighbour cache.
129 static u32 arp_hash(const void *pkey, const struct net_device *dev);
130 static int arp_constructor(struct neighbour *neigh);
131 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
132 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
133 static void parp_redo(struct sk_buff *skb);
135 static struct neigh_ops arp_generic_ops = {
137 solicit: arp_solicit,
138 error_report: arp_error_report,
139 output: neigh_resolve_output,
140 connected_output: neigh_connected_output,
141 hh_output: dev_queue_xmit,
142 queue_xmit: dev_queue_xmit,
145 static struct neigh_ops arp_hh_ops = {
147 solicit: arp_solicit,
148 error_report: arp_error_report,
149 output: neigh_resolve_output,
150 connected_output: neigh_resolve_output,
151 hh_output: dev_queue_xmit,
152 queue_xmit: dev_queue_xmit,
155 static struct neigh_ops arp_direct_ops = {
157 output: dev_queue_xmit,
158 connected_output: dev_queue_xmit,
159 hh_output: dev_queue_xmit,
160 queue_xmit: dev_queue_xmit,
163 struct neigh_ops arp_broken_ops = {
165 solicit: arp_solicit,
166 error_report: arp_error_report,
167 output: neigh_compat_output,
168 connected_output: neigh_compat_output,
169 hh_output: dev_queue_xmit,
170 queue_xmit: dev_queue_xmit,
173 struct neigh_table arp_tbl = {
175 entry_size: sizeof(struct neighbour) + 4,
178 constructor: arp_constructor,
179 proxy_redo: parp_redo,
183 base_reachable_time: 30 * HZ,
184 retrans_time: 1 * HZ,
185 gc_staletime: 60 * HZ,
186 reachable_time: 30 * HZ,
187 delay_probe_time: 5 * HZ,
191 anycast_delay: 1 * HZ,
192 proxy_delay: (8 * HZ) / 10,
196 gc_interval: 30 * HZ,
202 int arp_mc_map(u32 addr, u8 *haddr, struct net_device *dev, int dir)
208 ip_eth_mc_map(addr, haddr);
210 case ARPHRD_IEEE802_TR:
211 ip_tr_mc_map(addr, haddr);
215 memcpy(haddr, dev->broadcast, dev->addr_len);
223 static u32 arp_hash(const void *pkey, const struct net_device *dev)
225 return jhash_2words(*(u32 *)pkey, dev->ifindex, arp_tbl.hash_rnd);
228 static int arp_constructor(struct neighbour *neigh)
230 u32 addr = *(u32*)neigh->primary_key;
231 struct net_device *dev = neigh->dev;
232 struct in_device *in_dev = in_dev_get(dev);
237 neigh->type = inet_addr_type(addr);
238 if (in_dev->arp_parms)
239 neigh->parms = in_dev->arp_parms;
243 if (dev->hard_header == NULL) {
244 neigh->nud_state = NUD_NOARP;
245 neigh->ops = &arp_direct_ops;
246 neigh->output = neigh->ops->queue_xmit;
248 /* Good devices (checked by reading texts, but only Ethernet is
251 ARPHRD_ETHER: (ethernet, apfddi)
254 ARPHRD_METRICOM: (strip)
258 ARPHRD_IPDDP will also work, if author repairs it.
259 I did not it, because this driver does not work even
264 /* So... these "amateur" devices are hopeless.
265 The only thing, that I can say now:
266 It is very sad that we need to keep ugly obsolete
267 code to make them happy.
269 They should be moved to more reasonable state, now
270 they use rebuild_header INSTEAD OF hard_start_xmit!!!
271 Besides that, they are sort of out of date
272 (a lot of redundant clones/copies, useless in 2.1),
273 I wonder why people believe that they work.
279 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
281 #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
284 neigh->ops = &arp_broken_ops;
285 neigh->output = neigh->ops->output;
290 if (neigh->type == RTN_MULTICAST) {
291 neigh->nud_state = NUD_NOARP;
292 arp_mc_map(addr, neigh->ha, dev, 1);
293 } else if (dev->flags&(IFF_NOARP|IFF_LOOPBACK)) {
294 neigh->nud_state = NUD_NOARP;
295 memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
296 } else if (neigh->type == RTN_BROADCAST || dev->flags&IFF_POINTOPOINT) {
297 neigh->nud_state = NUD_NOARP;
298 memcpy(neigh->ha, dev->broadcast, dev->addr_len);
300 if (dev->hard_header_cache)
301 neigh->ops = &arp_hh_ops;
303 neigh->ops = &arp_generic_ops;
304 if (neigh->nud_state&NUD_VALID)
305 neigh->output = neigh->ops->connected_output;
307 neigh->output = neigh->ops->output;
312 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
314 dst_link_failure(skb);
318 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
322 struct net_device *dev = neigh->dev;
323 u32 target = *(u32*)neigh->primary_key;
324 int probes = atomic_read(&neigh->probes);
325 struct in_device *in_dev = in_dev_get(dev);
330 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
332 case 0: /* By default announce any local IP */
333 if (skb && inet_addr_type(skb->nh.iph->saddr) == RTN_LOCAL)
334 saddr = skb->nh.iph->saddr;
336 case 1: /* Restrict announcements of saddr in same subnet */
339 saddr = skb->nh.iph->saddr;
340 if (inet_addr_type(saddr) == RTN_LOCAL) {
341 /* saddr should be known to target */
342 if (inet_addr_onlink(in_dev, target, saddr))
347 case 2: /* Avoid secondary IPs, get a primary/preferred one */
354 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
356 if ((probes -= neigh->parms->ucast_probes) < 0) {
357 if (!(neigh->nud_state&NUD_VALID))
358 printk(KERN_DEBUG "trying to ucast probe in NUD_INVALID\n");
360 read_lock_bh(&neigh->lock);
361 } else if ((probes -= neigh->parms->app_probes) < 0) {
368 arp_send(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
369 dst_ha, dev->dev_addr, NULL);
371 read_unlock_bh(&neigh->lock);
374 static int arp_ignore(struct in_device *in_dev, struct net_device *dev,
379 switch (IN_DEV_ARP_IGNORE(in_dev)) {
380 case 0: /* Reply, the tip is already validated */
382 case 1: /* Reply only if tip is configured on the incoming interface */
384 scope = RT_SCOPE_HOST;
387 * Reply only if tip is configured on the incoming interface
388 * and is in same subnet as sip
390 scope = RT_SCOPE_HOST;
392 case 3: /* Do not reply for scope host addresses */
394 scope = RT_SCOPE_LINK;
397 case 4: /* Reserved */
402 case 8: /* Do not reply */
407 return !inet_confirm_addr(dev, sip, tip, scope);
410 static int arp_filter(__u32 sip, __u32 tip, struct net_device *dev)
414 /*unsigned long now; */
416 if (ip_route_output(&rt, sip, tip, 0, 0) < 0)
418 if (rt->u.dst.dev != dev) {
419 NET_INC_STATS_BH(ArpFilter);
426 /* OBSOLETE FUNCTIONS */
429 * Find an arp mapping in the cache. If not found, post a request.
431 * It is very UGLY routine: it DOES NOT use skb->dst->neighbour,
432 * even if it exists. It is supposed that skb->dev was mangled
433 * by a virtual device (eql, shaper). Nobody but broken devices
434 * is allowed to use this function, it is scheduled to be removed. --ANK
437 static int arp_set_predefined(int addr_hint, unsigned char * haddr, u32 paddr, struct net_device * dev)
441 printk(KERN_DEBUG "ARP: arp called for own IP address\n");
442 memcpy(haddr, dev->dev_addr, dev->addr_len);
445 arp_mc_map(paddr, haddr, dev, 1);
448 memcpy(haddr, dev->broadcast, dev->addr_len);
455 int arp_find(unsigned char *haddr, struct sk_buff *skb)
457 struct net_device *dev = skb->dev;
462 printk(KERN_DEBUG "arp_find is called with dst==NULL\n");
467 paddr = ((struct rtable*)skb->dst)->rt_gateway;
469 if (arp_set_predefined(inet_addr_type(paddr), haddr, paddr, dev))
472 n = __neigh_lookup(&arp_tbl, &paddr, dev, 1);
476 if (n->nud_state&NUD_VALID || neigh_event_send(n, skb) == 0) {
477 read_lock_bh(&n->lock);
478 memcpy(haddr, n->ha, dev->addr_len);
479 read_unlock_bh(&n->lock);
489 /* END OF OBSOLETE FUNCTIONS */
491 int arp_bind_neighbour(struct dst_entry *dst)
493 struct net_device *dev = dst->dev;
494 struct neighbour *n = dst->neighbour;
499 u32 nexthop = ((struct rtable*)dst)->rt_gateway;
500 if (dev->flags&(IFF_LOOPBACK|IFF_POINTOPOINT))
502 n = __neigh_lookup_errno(
503 #if defined(CONFIG_ATM_CLIP) || defined(CONFIG_ATM_CLIP_MODULE)
504 dev->type == ARPHRD_ATM ? clip_tbl_hook :
506 &arp_tbl, &nexthop, dev);
515 * Check if we can use proxy ARP for this path
518 static inline int arp_fwd_proxy(struct in_device *in_dev, struct rtable *rt)
520 struct in_device *out_dev;
523 if (!IN_DEV_PROXY_ARP(in_dev))
526 if ((imi = IN_DEV_MEDIUM_ID(in_dev)) == 0)
531 /* place to check for proxy_arp for routes */
533 if ((out_dev = in_dev_get(rt->u.dst.dev)) != NULL) {
534 omi = IN_DEV_MEDIUM_ID(out_dev);
537 return (omi != imi && omi != -1);
541 * Interface to link layer: send routine and receive handler.
545 * Create an arp packet. If (dest_hw == NULL), we create a broadcast
548 struct sk_buff *arp_create(int type, int ptype, u32 dest_ip,
549 struct net_device *dev, u32 src_ip,
550 unsigned char *dest_hw, unsigned char *src_hw,
551 unsigned char *target_hw)
555 unsigned char *arp_ptr;
561 skb = alloc_skb(sizeof(struct arphdr)+ 2*(dev->addr_len+4)
562 + dev->hard_header_len + 15, GFP_ATOMIC);
566 skb_reserve(skb, (dev->hard_header_len+15)&~15);
567 skb->nh.raw = skb->data;
568 arp = (struct arphdr *) skb_put(skb,sizeof(struct arphdr) + 2*(dev->addr_len+4));
570 skb->protocol = htons (ETH_P_ARP);
572 src_hw = dev->dev_addr;
574 dest_hw = dev->broadcast;
577 * Fill the device header for the ARP frame
579 if (dev->hard_header &&
580 dev->hard_header(skb,dev,ptype,dest_hw,src_hw,skb->len) < 0)
584 * Fill out the arp protocol part.
586 * The arp hardware type should match the device type, except for FDDI,
587 * which (according to RFC 1390) should always equal 1 (Ethernet).
590 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
591 * DIX code for the protocol. Make these device structure fields.
595 arp->ar_hrd = htons(dev->type);
596 arp->ar_pro = htons(ETH_P_IP);
599 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
601 arp->ar_hrd = htons(ARPHRD_AX25);
602 arp->ar_pro = htons(AX25_P_IP);
605 #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
607 arp->ar_hrd = htons(ARPHRD_NETROM);
608 arp->ar_pro = htons(AX25_P_IP);
615 arp->ar_hrd = htons(ARPHRD_ETHER);
616 arp->ar_pro = htons(ETH_P_IP);
620 case ARPHRD_IEEE802_TR:
621 arp->ar_hrd = htons(ARPHRD_IEEE802);
622 arp->ar_pro = htons(ETH_P_IP);
627 arp->ar_hln = dev->addr_len;
629 arp->ar_op = htons(type);
631 arp_ptr=(unsigned char *)(arp+1);
633 memcpy(arp_ptr, src_hw, dev->addr_len);
634 arp_ptr+=dev->addr_len;
635 memcpy(arp_ptr, &src_ip,4);
637 if (target_hw != NULL)
638 memcpy(arp_ptr, target_hw, dev->addr_len);
640 memset(arp_ptr, 0, dev->addr_len);
641 arp_ptr+=dev->addr_len;
642 memcpy(arp_ptr, &dest_ip, 4);
652 * Send an arp packet.
654 void arp_xmit(struct sk_buff *skb)
656 /* Send it off, maybe filter it using firewalling first. */
657 NF_HOOK(NF_ARP, NF_ARP_OUT, skb, NULL, skb->dev, dev_queue_xmit);
661 * Create and send an arp packet.
663 void arp_send(int type, int ptype, u32 dest_ip,
664 struct net_device *dev, u32 src_ip,
665 unsigned char *dest_hw, unsigned char *src_hw,
666 unsigned char *target_hw)
671 * No arp on this interface.
674 if (dev->flags&IFF_NOARP)
677 skb = arp_create(type, ptype, dest_ip, dev, src_ip,
678 dest_hw, src_hw, target_hw);
686 static void parp_redo(struct sk_buff *skb)
688 arp_rcv(skb, skb->dev, NULL);
692 * Process an arp request.
695 int arp_process(struct sk_buff *skb)
697 struct net_device *dev = skb->dev;
698 struct in_device *in_dev = in_dev_get(dev);
700 unsigned char *arp_ptr;
702 unsigned char *sha, *tha;
704 u16 dev_type = dev->type;
708 /* arp_rcv below verifies the ARP header, verifies the device
709 * is ARP'able, and linearizes the SKB (if needed).
716 arp_ptr= (unsigned char *)(arp+1);
720 if (arp->ar_pro != htons(ETH_P_IP))
722 if (htons(dev_type) != arp->ar_hrd)
725 #ifdef CONFIG_NET_ETHERNET
728 * ETHERNET devices will accept ARP hardware types of either
729 * 1 (Ethernet) or 6 (IEEE 802.2).
731 if (arp->ar_hrd != htons(ARPHRD_ETHER) &&
732 arp->ar_hrd != htons(ARPHRD_IEEE802))
734 if (arp->ar_pro != htons(ETH_P_IP))
739 case ARPHRD_IEEE802_TR:
741 * Token ring devices will accept ARP hardware types of either
742 * 1 (Ethernet) or 6 (IEEE 802.2).
744 if (arp->ar_hrd != htons(ARPHRD_ETHER) &&
745 arp->ar_hrd != htons(ARPHRD_IEEE802))
747 if (arp->ar_pro != htons(ETH_P_IP))
754 * According to RFC 1390, FDDI devices should accept ARP hardware types
755 * of 1 (Ethernet). However, to be more robust, we'll accept hardware
756 * types of either 1 (Ethernet) or 6 (IEEE 802.2).
758 if (arp->ar_hrd != htons(ARPHRD_ETHER) &&
759 arp->ar_hrd != htons(ARPHRD_IEEE802))
761 if (arp->ar_pro != htons(ETH_P_IP))
768 * According to RFC 2625, Fibre Channel devices (which are IEEE
769 * 802 devices) should accept ARP hardware types of 6 (IEEE 802)
772 if (arp->ar_hrd != htons(ARPHRD_ETHER) &&
773 arp->ar_hrd != htons(ARPHRD_IEEE802))
775 if (arp->ar_pro != htons(ETH_P_IP))
779 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
781 if (arp->ar_pro != htons(AX25_P_IP))
783 if (arp->ar_hrd != htons(ARPHRD_AX25))
786 #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
788 if (arp->ar_pro != htons(AX25_P_IP))
790 if (arp->ar_hrd != htons(ARPHRD_NETROM))
797 /* Understand only these message types */
799 if (arp->ar_op != htons(ARPOP_REPLY) &&
800 arp->ar_op != htons(ARPOP_REQUEST))
807 arp_ptr += dev->addr_len;
808 memcpy(&sip, arp_ptr, 4);
811 arp_ptr += dev->addr_len;
812 memcpy(&tip, arp_ptr, 4);
814 * Check for bad requests for 127.x.x.x and requests for multicast
815 * addresses. If this is one such, delete it.
817 if (LOOPBACK(tip) || MULTICAST(tip))
821 * Special case: We must set Frame Relay source Q.922 address
823 if (dev_type == ARPHRD_DLCI)
824 sha = dev->broadcast;
827 * Process entry. The idea here is we want to send a reply if it is a
828 * request for us or if it is a request for someone else that we hold
829 * a proxy for. We want to add an entry to our cache if it is a reply
830 * to us or if it is a request for our address.
831 * (The assumption for this last is that if someone is requesting our
832 * address, they are probably intending to talk to us, so it saves time
833 * if we cache their address. Their address is also probably not in
834 * our cache, since ours is not in their cache.)
836 * Putting this another way, we only care about replies if they are to
837 * us, in which case we add them to the cache. For requests, we care
838 * about those for us and those for our proxies. We reply to both,
839 * and in the case of requests for us we add the requester to the arp
843 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
845 if (arp->ar_op == htons(ARPOP_REQUEST) &&
846 inet_addr_type(tip) == RTN_LOCAL &&
847 !arp_ignore(in_dev,dev,sip,tip))
848 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, sha,
853 if (arp->ar_op == htons(ARPOP_REQUEST) &&
854 ip_route_input(skb, tip, sip, 0, dev) == 0) {
856 rt = (struct rtable*)skb->dst;
857 addr_type = rt->rt_type;
859 if (addr_type == RTN_LOCAL) {
860 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
865 dont_send |= arp_ignore(in_dev,dev,sip,tip);
866 if (!dont_send && IN_DEV_ARPFILTER(in_dev))
867 dont_send |= arp_filter(sip,tip,dev);
869 arp_send(ARPOP_REPLY,ETH_P_ARP,sip,dev,tip,sha,dev->dev_addr,sha);
874 } else if (IN_DEV_FORWARD(in_dev)) {
875 if ((rt->rt_flags&RTCF_DNAT) ||
876 (addr_type == RTN_UNICAST && rt->u.dst.dev != dev &&
877 (arp_fwd_proxy(in_dev, rt) || pneigh_lookup(&arp_tbl, &tip, dev, 0)))) {
878 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
882 if (skb->stamp.tv_sec == 0 ||
883 skb->pkt_type == PACKET_HOST ||
884 in_dev->arp_parms->proxy_delay == 0) {
885 arp_send(ARPOP_REPLY,ETH_P_ARP,sip,dev,tip,sha,dev->dev_addr,sha);
887 pneigh_enqueue(&arp_tbl, in_dev->arp_parms, skb);
896 /* Update our ARP tables */
898 n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
900 #ifdef CONFIG_IP_ACCEPT_UNSOLICITED_ARP
901 /* Unsolicited ARP is not accepted by default.
902 It is possible, that this option should be enabled for some
903 devices (strip is candidate)
906 arp->ar_op == htons(ARPOP_REPLY) &&
907 inet_addr_type(sip) == RTN_UNICAST)
908 n = __neigh_lookup(&arp_tbl, &sip, dev, -1);
912 int state = NUD_REACHABLE;
915 /* If several different ARP replies follows back-to-back,
916 use the FIRST one. It is possible, if several proxy
917 agents are active. Taking the first reply prevents
918 arp trashing and chooses the fastest router.
920 if (jiffies - n->updated >= n->parms->locktime)
923 /* Broadcast replies and request packets
924 do not assert neighbour reachability.
926 if (arp->ar_op != htons(ARPOP_REPLY) ||
927 skb->pkt_type != PACKET_HOST)
929 neigh_update(n, sha, state, override, 1);
942 * Receive an arp request from the device layer.
945 int arp_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt)
949 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
950 if (!pskb_may_pull(skb, (sizeof(struct arphdr) +
951 (2 * dev->addr_len) +
956 if (arp->ar_hln != dev->addr_len ||
957 dev->flags & IFF_NOARP ||
958 skb->pkt_type == PACKET_OTHERHOST ||
959 skb->pkt_type == PACKET_LOOPBACK ||
963 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
966 return NF_HOOK(NF_ARP, NF_ARP_IN, skb, dev, NULL, arp_process);
975 * User level interface (ioctl, /proc)
979 * Set (create) an ARP cache entry.
982 int arp_req_set(struct arpreq *r, struct net_device * dev)
984 u32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
985 struct neighbour *neigh;
988 if (r->arp_flags&ATF_PUBL) {
989 u32 mask = ((struct sockaddr_in *) &r->arp_netmask)->sin_addr.s_addr;
990 if (mask && mask != 0xFFFFFFFF)
992 if (!dev && (r->arp_flags & ATF_COM)) {
993 dev = dev_getbyhwaddr(r->arp_ha.sa_family, r->arp_ha.sa_data);
998 if (pneigh_lookup(&arp_tbl, &ip, dev, 1) == NULL)
1003 ipv4_devconf.proxy_arp = 1;
1006 if (__in_dev_get(dev)) {
1007 __in_dev_get(dev)->cnf.proxy_arp = 1;
1013 if (r->arp_flags & ATF_PERM)
1014 r->arp_flags |= ATF_COM;
1017 if ((err = ip_route_output(&rt, ip, 0, RTO_ONLINK, 0)) != 0)
1019 dev = rt->u.dst.dev;
1024 switch (dev->type) {
1028 * According to RFC 1390, FDDI devices should accept ARP
1029 * hardware types of 1 (Ethernet). However, to be more
1030 * robust, we'll accept hardware types of either 1 (Ethernet)
1031 * or 6 (IEEE 802.2).
1033 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1034 r->arp_ha.sa_family != ARPHRD_ETHER &&
1035 r->arp_ha.sa_family != ARPHRD_IEEE802)
1040 if (r->arp_ha.sa_family != dev->type)
1045 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1046 err = PTR_ERR(neigh);
1047 if (!IS_ERR(neigh)) {
1048 unsigned state = NUD_STALE;
1049 if (r->arp_flags & ATF_PERM)
1050 state = NUD_PERMANENT;
1051 err = neigh_update(neigh, (r->arp_flags&ATF_COM) ?
1052 r->arp_ha.sa_data : NULL, state, 1, 0);
1053 neigh_release(neigh);
1058 static unsigned arp_state_to_flags(struct neighbour *neigh)
1061 if (neigh->nud_state&NUD_PERMANENT)
1062 flags = ATF_PERM|ATF_COM;
1063 else if (neigh->nud_state&NUD_VALID)
1069 * Get an ARP cache entry.
1072 static int arp_req_get(struct arpreq *r, struct net_device *dev)
1074 u32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1075 struct neighbour *neigh;
1078 neigh = neigh_lookup(&arp_tbl, &ip, dev);
1080 read_lock_bh(&neigh->lock);
1081 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
1082 r->arp_flags = arp_state_to_flags(neigh);
1083 read_unlock_bh(&neigh->lock);
1084 r->arp_ha.sa_family = dev->type;
1085 strncpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1086 neigh_release(neigh);
1092 int arp_req_delete(struct arpreq *r, struct net_device * dev)
1095 u32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1096 struct neighbour *neigh;
1098 if (r->arp_flags & ATF_PUBL) {
1099 u32 mask = ((struct sockaddr_in *) &r->arp_netmask)->sin_addr.s_addr;
1100 if (mask == 0xFFFFFFFF)
1101 return pneigh_delete(&arp_tbl, &ip, dev);
1104 ipv4_devconf.proxy_arp = 0;
1107 if (__in_dev_get(dev)) {
1108 __in_dev_get(dev)->cnf.proxy_arp = 0;
1118 if ((err = ip_route_output(&rt, ip, 0, RTO_ONLINK, 0)) != 0)
1120 dev = rt->u.dst.dev;
1126 neigh = neigh_lookup(&arp_tbl, &ip, dev);
1128 if (neigh->nud_state&~NUD_NOARP)
1129 err = neigh_update(neigh, NULL, NUD_FAILED, 1, 0);
1130 neigh_release(neigh);
1136 * Handle an ARP layer I/O control request.
1139 int arp_ioctl(unsigned int cmd, void *arg)
1143 struct net_device * dev = NULL;
1148 if (!capable(CAP_NET_ADMIN))
1151 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1159 if (r.arp_pa.sa_family != AF_INET)
1160 return -EPFNOSUPPORT;
1162 if (!(r.arp_flags & ATF_PUBL) &&
1163 (r.arp_flags & (ATF_NETMASK|ATF_DONTPUB)))
1165 if (!(r.arp_flags & ATF_NETMASK))
1166 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr=htonl(0xFFFFFFFFUL);
1171 if ((dev = __dev_get_by_name(r.arp_dev)) == NULL)
1174 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1175 if (!r.arp_ha.sa_family)
1176 r.arp_ha.sa_family = dev->type;
1178 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1180 } else if (cmd == SIOCGARP) {
1187 err = arp_req_delete(&r, dev);
1190 err = arp_req_set(&r, dev);
1193 err = arp_req_get(&r, dev);
1194 if (!err && copy_to_user(arg, &r, sizeof(r)))
1203 #ifdef CONFIG_PROC_FS
1204 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1206 /* ------------------------------------------------------------------------ */
1208 * ax25 -> ASCII conversion
1210 static char *ax2asc2(ax25_address *a, char *buf)
1215 for (n = 0, s = buf; n < 6; n++) {
1216 c = (a->ax25_call[n] >> 1) & 0x7F;
1218 if (c != ' ') *s++ = c;
1223 if ((n = ((a->ax25_call[6] >> 1) & 0x0F)) > 9) {
1231 if (*buf == '\0' || *buf == '-')
1237 #endif /* CONFIG_AX25 */
1239 #define HBUFFERLEN 30
1241 static void arp_format_neigh_entry(struct seq_file *seq,
1242 struct neighbour *n)
1244 char hbuffer[HBUFFERLEN];
1245 const char hexbuf[] = "0123456789ABCDEF";
1248 struct net_device *dev = n->dev;
1249 int hatype = dev->type;
1251 read_lock(&n->lock);
1253 /* Convert hardware address to XX:XX:XX:XX ... form. */
1254 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1255 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1256 ax2asc2((ax25_address *)n->ha, hbuffer);
1259 for (k=0,j=0;k<HBUFFERLEN-3 && j<dev->addr_len;j++) {
1260 hbuffer[k++]=hexbuf[(n->ha[j]>>4)&15 ];
1261 hbuffer[k++]=hexbuf[n->ha[j]&15 ];
1265 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1268 sprintf(tbuf, "%u.%u.%u.%u", NIPQUAD(*(u32*)n->primary_key));
1269 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1270 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1271 read_unlock(&n->lock);
1274 static void arp_format_pneigh_entry(struct seq_file *seq,
1275 struct pneigh_entry *n)
1277 struct net_device *dev = n->dev;
1278 int hatype = dev ? dev->type : 0;
1281 sprintf(tbuf, "%u.%u.%u.%u", NIPQUAD(*(u32*)n->key));
1282 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1283 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1284 dev ? dev->name : "*");
1287 static int arp_seq_show(struct seq_file *seq, void *v)
1289 if (v == SEQ_START_TOKEN) {
1290 seq_puts(seq, "IP address HW type Flags "
1291 "HW address Mask Device\n");
1293 struct neigh_seq_state *state = seq->private;
1295 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1296 arp_format_pneigh_entry(seq, v);
1298 arp_format_neigh_entry(seq, v);
1304 static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1306 /* Don't want to confuse "arp -a" w/ magic entries,
1307 * so we tell the generic iterator to skip NUD_NOARP.
1309 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1312 /* ------------------------------------------------------------------------ */
1314 static struct seq_operations arp_seq_ops = {
1315 .start = arp_seq_start,
1316 .next = neigh_seq_next,
1317 .stop = neigh_seq_stop,
1318 .show = arp_seq_show,
1321 static int arp_seq_open(struct inode *inode, struct file *file)
1323 struct seq_file *seq;
1325 struct neigh_seq_state *s = kmalloc(sizeof(*s), GFP_KERNEL);
1330 memset(s, 0, sizeof(*s));
1331 rc = seq_open(file, &arp_seq_ops);
1335 seq = file->private_data;
1344 static struct file_operations arp_seq_fops = {
1345 .owner = THIS_MODULE,
1346 .open = arp_seq_open,
1348 .llseek = seq_lseek,
1349 .release = seq_release_private,
1351 #endif /* CONFIG_PROC_FS */
1353 static int arp_netdev_event(struct notifier_block *this, unsigned long event, void *ptr)
1355 struct net_device *dev = ptr;
1358 case NETDEV_CHANGEADDR:
1359 neigh_changeaddr(&arp_tbl, dev);
1369 struct notifier_block arp_netdev_notifier = {
1370 .notifier_call = arp_netdev_event,
1373 /* Note, that it is not on notifier chain.
1374 It is necessary, that this routine was called after route cache will be
1377 void arp_ifdown(struct net_device *dev)
1379 neigh_ifdown(&arp_tbl, dev);
1384 * Called once on startup.
1387 static struct packet_type arp_packet_type = {
1388 type: __constant_htons(ETH_P_ARP),
1390 data: (void*) 1, /* understand shared skbs */
1393 void __init arp_init (void)
1395 neigh_table_init(&arp_tbl);
1397 dev_add_pack(&arp_packet_type);
1399 #ifdef CONFIG_PROC_FS
1400 if (!proc_net_fops_create("arp", S_IRUGO, &arp_seq_fops))
1401 panic("unable to create arp proc entry");
1403 #ifdef CONFIG_SYSCTL
1404 neigh_sysctl_register(NULL, &arp_tbl.parms, NET_IPV4, NET_IPV4_NEIGH, "ipv4");
1406 register_netdevice_notifier(&arp_netdev_notifier);