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/capability.h>
82 #include <linux/socket.h>
83 #include <linux/sockios.h>
84 #include <linux/errno.h>
87 #include <linux/inet.h>
88 #include <linux/inetdevice.h>
89 #include <linux/netdevice.h>
90 #include <linux/etherdevice.h>
91 #include <linux/fddidevice.h>
92 #include <linux/if_arp.h>
93 #include <linux/trdevice.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/jhash.h>
103 #include <linux/sysctl.h>
106 #include <net/net_namespace.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(__be32 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->header_ops) {
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);
314 if (dev->header_ops->cache)
315 neigh->ops = &arp_hh_ops;
317 neigh->ops = &arp_generic_ops;
319 if (neigh->nud_state&NUD_VALID)
320 neigh->output = neigh->ops->connected_output;
322 neigh->output = neigh->ops->output;
327 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
329 dst_link_failure(skb);
333 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
337 struct net_device *dev = neigh->dev;
338 __be32 target = *(__be32*)neigh->primary_key;
339 int probes = atomic_read(&neigh->probes);
340 struct in_device *in_dev = in_dev_get(dev);
345 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
347 case 0: /* By default announce any local IP */
348 if (skb && inet_addr_type(ip_hdr(skb)->saddr) == RTN_LOCAL)
349 saddr = ip_hdr(skb)->saddr;
351 case 1: /* Restrict announcements of saddr in same subnet */
354 saddr = ip_hdr(skb)->saddr;
355 if (inet_addr_type(saddr) == RTN_LOCAL) {
356 /* saddr should be known to target */
357 if (inet_addr_onlink(in_dev, target, saddr))
362 case 2: /* Avoid secondary IPs, get a primary/preferred one */
369 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
371 if ((probes -= neigh->parms->ucast_probes) < 0) {
372 if (!(neigh->nud_state&NUD_VALID))
373 printk(KERN_DEBUG "trying to ucast probe in NUD_INVALID\n");
375 read_lock_bh(&neigh->lock);
376 } else if ((probes -= neigh->parms->app_probes) < 0) {
383 arp_send(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
384 dst_ha, dev->dev_addr, NULL);
386 read_unlock_bh(&neigh->lock);
389 static int arp_ignore(struct in_device *in_dev, struct net_device *dev,
390 __be32 sip, __be32 tip)
394 switch (IN_DEV_ARP_IGNORE(in_dev)) {
395 case 0: /* Reply, the tip is already validated */
397 case 1: /* Reply only if tip is configured on the incoming interface */
399 scope = RT_SCOPE_HOST;
402 * Reply only if tip is configured on the incoming interface
403 * and is in same subnet as sip
405 scope = RT_SCOPE_HOST;
407 case 3: /* Do not reply for scope host addresses */
409 scope = RT_SCOPE_LINK;
412 case 4: /* Reserved */
417 case 8: /* Do not reply */
422 return !inet_confirm_addr(dev, sip, tip, scope);
425 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
427 struct flowi fl = { .nl_u = { .ip4_u = { .daddr = sip,
431 /*unsigned long now; */
433 if (ip_route_output_key(&rt, &fl) < 0)
435 if (rt->u.dst.dev != dev) {
436 NET_INC_STATS_BH(LINUX_MIB_ARPFILTER);
443 /* OBSOLETE FUNCTIONS */
446 * Find an arp mapping in the cache. If not found, post a request.
448 * It is very UGLY routine: it DOES NOT use skb->dst->neighbour,
449 * even if it exists. It is supposed that skb->dev was mangled
450 * by a virtual device (eql, shaper). Nobody but broken devices
451 * is allowed to use this function, it is scheduled to be removed. --ANK
454 static int arp_set_predefined(int addr_hint, unsigned char * haddr, __be32 paddr, struct net_device * dev)
458 printk(KERN_DEBUG "ARP: arp called for own IP address\n");
459 memcpy(haddr, dev->dev_addr, dev->addr_len);
462 arp_mc_map(paddr, haddr, dev, 1);
465 memcpy(haddr, dev->broadcast, dev->addr_len);
472 int arp_find(unsigned char *haddr, struct sk_buff *skb)
474 struct net_device *dev = skb->dev;
479 printk(KERN_DEBUG "arp_find is called with dst==NULL\n");
484 paddr = ((struct rtable*)skb->dst)->rt_gateway;
486 if (arp_set_predefined(inet_addr_type(paddr), haddr, paddr, dev))
489 n = __neigh_lookup(&arp_tbl, &paddr, dev, 1);
493 if (n->nud_state&NUD_VALID || neigh_event_send(n, skb) == 0) {
494 read_lock_bh(&n->lock);
495 memcpy(haddr, n->ha, dev->addr_len);
496 read_unlock_bh(&n->lock);
506 /* END OF OBSOLETE FUNCTIONS */
508 int arp_bind_neighbour(struct dst_entry *dst)
510 struct net_device *dev = dst->dev;
511 struct neighbour *n = dst->neighbour;
516 __be32 nexthop = ((struct rtable*)dst)->rt_gateway;
517 if (dev->flags&(IFF_LOOPBACK|IFF_POINTOPOINT))
519 n = __neigh_lookup_errno(
520 #if defined(CONFIG_ATM_CLIP) || defined(CONFIG_ATM_CLIP_MODULE)
521 dev->type == ARPHRD_ATM ? clip_tbl_hook :
523 &arp_tbl, &nexthop, dev);
532 * Check if we can use proxy ARP for this path
535 static inline int arp_fwd_proxy(struct in_device *in_dev, struct rtable *rt)
537 struct in_device *out_dev;
540 if (!IN_DEV_PROXY_ARP(in_dev))
543 if ((imi = IN_DEV_MEDIUM_ID(in_dev)) == 0)
548 /* place to check for proxy_arp for routes */
550 if ((out_dev = in_dev_get(rt->u.dst.dev)) != NULL) {
551 omi = IN_DEV_MEDIUM_ID(out_dev);
554 return (omi != imi && omi != -1);
558 * Interface to link layer: send routine and receive handler.
562 * Create an arp packet. If (dest_hw == NULL), we create a broadcast
565 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
566 struct net_device *dev, __be32 src_ip,
567 unsigned char *dest_hw, unsigned char *src_hw,
568 unsigned char *target_hw)
572 unsigned char *arp_ptr;
578 skb = alloc_skb(sizeof(struct arphdr)+ 2*(dev->addr_len+4)
579 + LL_RESERVED_SPACE(dev), GFP_ATOMIC);
583 skb_reserve(skb, LL_RESERVED_SPACE(dev));
584 skb_reset_network_header(skb);
585 arp = (struct arphdr *) skb_put(skb,sizeof(struct arphdr) + 2*(dev->addr_len+4));
587 skb->protocol = htons(ETH_P_ARP);
589 src_hw = dev->dev_addr;
591 dest_hw = dev->broadcast;
594 * Fill the device header for the ARP frame
596 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
600 * Fill out the arp protocol part.
602 * The arp hardware type should match the device type, except for FDDI,
603 * which (according to RFC 1390) should always equal 1 (Ethernet).
606 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
607 * DIX code for the protocol. Make these device structure fields.
611 arp->ar_hrd = htons(dev->type);
612 arp->ar_pro = htons(ETH_P_IP);
615 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
617 arp->ar_hrd = htons(ARPHRD_AX25);
618 arp->ar_pro = htons(AX25_P_IP);
621 #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
623 arp->ar_hrd = htons(ARPHRD_NETROM);
624 arp->ar_pro = htons(AX25_P_IP);
631 arp->ar_hrd = htons(ARPHRD_ETHER);
632 arp->ar_pro = htons(ETH_P_IP);
636 case ARPHRD_IEEE802_TR:
637 arp->ar_hrd = htons(ARPHRD_IEEE802);
638 arp->ar_pro = htons(ETH_P_IP);
643 arp->ar_hln = dev->addr_len;
645 arp->ar_op = htons(type);
647 arp_ptr=(unsigned char *)(arp+1);
649 memcpy(arp_ptr, src_hw, dev->addr_len);
650 arp_ptr+=dev->addr_len;
651 memcpy(arp_ptr, &src_ip,4);
653 if (target_hw != NULL)
654 memcpy(arp_ptr, target_hw, dev->addr_len);
656 memset(arp_ptr, 0, dev->addr_len);
657 arp_ptr+=dev->addr_len;
658 memcpy(arp_ptr, &dest_ip, 4);
668 * Send an arp packet.
670 void arp_xmit(struct sk_buff *skb)
672 /* Send it off, maybe filter it using firewalling first. */
673 NF_HOOK(NF_ARP, NF_ARP_OUT, skb, NULL, skb->dev, dev_queue_xmit);
677 * Create and send an arp packet.
679 void arp_send(int type, int ptype, __be32 dest_ip,
680 struct net_device *dev, __be32 src_ip,
681 unsigned char *dest_hw, unsigned char *src_hw,
682 unsigned char *target_hw)
687 * No arp on this interface.
690 if (dev->flags&IFF_NOARP)
693 skb = arp_create(type, ptype, dest_ip, dev, src_ip,
694 dest_hw, src_hw, target_hw);
703 * Process an arp request.
706 static int arp_process(struct sk_buff *skb)
708 struct net_device *dev = skb->dev;
709 struct in_device *in_dev = in_dev_get(dev);
711 unsigned char *arp_ptr;
713 unsigned char *sha, *tha;
715 u16 dev_type = dev->type;
719 /* arp_rcv below verifies the ARP header and verifies the device
730 if (arp->ar_pro != htons(ETH_P_IP) ||
731 htons(dev_type) != arp->ar_hrd)
734 #ifdef CONFIG_NET_ETHERNET
738 case ARPHRD_IEEE802_TR:
746 #if defined(CONFIG_NET_ETHERNET) || defined(CONFIG_TR) || \
747 defined(CONFIG_FDDI) || defined(CONFIG_NET_FC)
749 * ETHERNET, Token Ring and Fibre Channel (which are IEEE 802
750 * devices, according to RFC 2625) devices will accept ARP
751 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
752 * This is the case also of FDDI, where the RFC 1390 says that
753 * FDDI devices should accept ARP hardware of (1) Ethernet,
754 * however, to be more robust, we'll accept both 1 (Ethernet)
757 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
758 arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
759 arp->ar_pro != htons(ETH_P_IP))
763 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
765 if (arp->ar_pro != htons(AX25_P_IP) ||
766 arp->ar_hrd != htons(ARPHRD_AX25))
769 #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
771 if (arp->ar_pro != htons(AX25_P_IP) ||
772 arp->ar_hrd != htons(ARPHRD_NETROM))
779 /* Understand only these message types */
781 if (arp->ar_op != htons(ARPOP_REPLY) &&
782 arp->ar_op != htons(ARPOP_REQUEST))
788 arp_ptr= (unsigned char *)(arp+1);
790 arp_ptr += dev->addr_len;
791 memcpy(&sip, arp_ptr, 4);
794 arp_ptr += dev->addr_len;
795 memcpy(&tip, arp_ptr, 4);
797 * Check for bad requests for 127.x.x.x and requests for multicast
798 * addresses. If this is one such, delete it.
800 if (LOOPBACK(tip) || MULTICAST(tip))
804 * Special case: We must set Frame Relay source Q.922 address
806 if (dev_type == ARPHRD_DLCI)
807 sha = dev->broadcast;
810 * Process entry. The idea here is we want to send a reply if it is a
811 * request for us or if it is a request for someone else that we hold
812 * a proxy for. We want to add an entry to our cache if it is a reply
813 * to us or if it is a request for our address.
814 * (The assumption for this last is that if someone is requesting our
815 * address, they are probably intending to talk to us, so it saves time
816 * if we cache their address. Their address is also probably not in
817 * our cache, since ours is not in their cache.)
819 * Putting this another way, we only care about replies if they are to
820 * us, in which case we add them to the cache. For requests, we care
821 * about those for us and those for our proxies. We reply to both,
822 * and in the case of requests for us we add the requester to the arp
826 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
828 if (arp->ar_op == htons(ARPOP_REQUEST) &&
829 inet_addr_type(tip) == RTN_LOCAL &&
830 !arp_ignore(in_dev,dev,sip,tip))
831 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, sha,
836 if (arp->ar_op == htons(ARPOP_REQUEST) &&
837 ip_route_input(skb, tip, sip, 0, dev) == 0) {
839 rt = (struct rtable*)skb->dst;
840 addr_type = rt->rt_type;
842 if (addr_type == RTN_LOCAL) {
843 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
848 dont_send |= arp_ignore(in_dev,dev,sip,tip);
849 if (!dont_send && IN_DEV_ARPFILTER(in_dev))
850 dont_send |= arp_filter(sip,tip,dev);
852 arp_send(ARPOP_REPLY,ETH_P_ARP,sip,dev,tip,sha,dev->dev_addr,sha);
857 } else if (IN_DEV_FORWARD(in_dev)) {
858 if ((rt->rt_flags&RTCF_DNAT) ||
859 (addr_type == RTN_UNICAST && rt->u.dst.dev != dev &&
860 (arp_fwd_proxy(in_dev, rt) || pneigh_lookup(&arp_tbl, &tip, dev, 0)))) {
861 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
865 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
866 skb->pkt_type == PACKET_HOST ||
867 in_dev->arp_parms->proxy_delay == 0) {
868 arp_send(ARPOP_REPLY,ETH_P_ARP,sip,dev,tip,sha,dev->dev_addr,sha);
870 pneigh_enqueue(&arp_tbl, in_dev->arp_parms, skb);
879 /* Update our ARP tables */
881 n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
883 if (IPV4_DEVCONF_ALL(ARP_ACCEPT)) {
884 /* Unsolicited ARP is not accepted by default.
885 It is possible, that this option should be enabled for some
886 devices (strip is candidate)
889 arp->ar_op == htons(ARPOP_REPLY) &&
890 inet_addr_type(sip) == RTN_UNICAST)
891 n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
895 int state = NUD_REACHABLE;
898 /* If several different ARP replies follows back-to-back,
899 use the FIRST one. It is possible, if several proxy
900 agents are active. Taking the first reply prevents
901 arp trashing and chooses the fastest router.
903 override = time_after(jiffies, n->updated + n->parms->locktime);
905 /* Broadcast replies and request packets
906 do not assert neighbour reachability.
908 if (arp->ar_op != htons(ARPOP_REPLY) ||
909 skb->pkt_type != PACKET_HOST)
911 neigh_update(n, sha, state, override ? NEIGH_UPDATE_F_OVERRIDE : 0);
922 static void parp_redo(struct sk_buff *skb)
929 * Receive an arp request from the device layer.
932 static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
933 struct packet_type *pt, struct net_device *orig_dev)
937 if (dev->nd_net != &init_net)
940 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
941 if (!pskb_may_pull(skb, (sizeof(struct arphdr) +
942 (2 * dev->addr_len) +
947 if (arp->ar_hln != dev->addr_len ||
948 dev->flags & IFF_NOARP ||
949 skb->pkt_type == PACKET_OTHERHOST ||
950 skb->pkt_type == PACKET_LOOPBACK ||
954 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
957 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
959 return NF_HOOK(NF_ARP, NF_ARP_IN, skb, dev, NULL, arp_process);
968 * User level interface (ioctl)
972 * Set (create) an ARP cache entry.
975 static int arp_req_set(struct arpreq *r, struct net_device * dev)
977 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
978 struct neighbour *neigh;
981 if (r->arp_flags&ATF_PUBL) {
982 __be32 mask = ((struct sockaddr_in *) &r->arp_netmask)->sin_addr.s_addr;
983 if (mask && mask != htonl(0xFFFFFFFF))
985 if (!dev && (r->arp_flags & ATF_COM)) {
986 dev = dev_getbyhwaddr(&init_net, r->arp_ha.sa_family, r->arp_ha.sa_data);
991 if (pneigh_lookup(&arp_tbl, &ip, dev, 1) == NULL)
996 IPV4_DEVCONF_ALL(PROXY_ARP) = 1;
999 if (__in_dev_get_rtnl(dev)) {
1000 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, 1);
1006 if (r->arp_flags & ATF_PERM)
1007 r->arp_flags |= ATF_COM;
1009 struct flowi fl = { .nl_u = { .ip4_u = { .daddr = ip,
1010 .tos = RTO_ONLINK } } };
1012 if ((err = ip_route_output_key(&rt, &fl)) != 0)
1014 dev = rt->u.dst.dev;
1019 switch (dev->type) {
1023 * According to RFC 1390, FDDI devices should accept ARP
1024 * hardware types of 1 (Ethernet). However, to be more
1025 * robust, we'll accept hardware types of either 1 (Ethernet)
1026 * or 6 (IEEE 802.2).
1028 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1029 r->arp_ha.sa_family != ARPHRD_ETHER &&
1030 r->arp_ha.sa_family != ARPHRD_IEEE802)
1035 if (r->arp_ha.sa_family != dev->type)
1040 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1041 err = PTR_ERR(neigh);
1042 if (!IS_ERR(neigh)) {
1043 unsigned state = NUD_STALE;
1044 if (r->arp_flags & ATF_PERM)
1045 state = NUD_PERMANENT;
1046 err = neigh_update(neigh, (r->arp_flags&ATF_COM) ?
1047 r->arp_ha.sa_data : NULL, state,
1048 NEIGH_UPDATE_F_OVERRIDE|
1049 NEIGH_UPDATE_F_ADMIN);
1050 neigh_release(neigh);
1055 static unsigned arp_state_to_flags(struct neighbour *neigh)
1058 if (neigh->nud_state&NUD_PERMANENT)
1059 flags = ATF_PERM|ATF_COM;
1060 else if (neigh->nud_state&NUD_VALID)
1066 * Get an ARP cache entry.
1069 static int arp_req_get(struct arpreq *r, struct net_device *dev)
1071 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1072 struct neighbour *neigh;
1075 neigh = neigh_lookup(&arp_tbl, &ip, dev);
1077 read_lock_bh(&neigh->lock);
1078 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
1079 r->arp_flags = arp_state_to_flags(neigh);
1080 read_unlock_bh(&neigh->lock);
1081 r->arp_ha.sa_family = dev->type;
1082 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1083 neigh_release(neigh);
1089 static int arp_req_delete(struct arpreq *r, struct net_device * dev)
1092 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1093 struct neighbour *neigh;
1095 if (r->arp_flags & ATF_PUBL) {
1097 ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1098 if (mask == htonl(0xFFFFFFFF))
1099 return pneigh_delete(&arp_tbl, &ip, dev);
1102 IPV4_DEVCONF_ALL(PROXY_ARP) = 0;
1105 if (__in_dev_get_rtnl(dev)) {
1106 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev),
1116 struct flowi fl = { .nl_u = { .ip4_u = { .daddr = ip,
1117 .tos = RTO_ONLINK } } };
1119 if ((err = ip_route_output_key(&rt, &fl)) != 0)
1121 dev = rt->u.dst.dev;
1127 neigh = neigh_lookup(&arp_tbl, &ip, dev);
1129 if (neigh->nud_state&~NUD_NOARP)
1130 err = neigh_update(neigh, NULL, NUD_FAILED,
1131 NEIGH_UPDATE_F_OVERRIDE|
1132 NEIGH_UPDATE_F_ADMIN);
1133 neigh_release(neigh);
1139 * Handle an ARP layer I/O control request.
1142 int arp_ioctl(unsigned int cmd, void __user *arg)
1146 struct net_device *dev = NULL;
1151 if (!capable(CAP_NET_ADMIN))
1154 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1162 if (r.arp_pa.sa_family != AF_INET)
1163 return -EPFNOSUPPORT;
1165 if (!(r.arp_flags & ATF_PUBL) &&
1166 (r.arp_flags & (ATF_NETMASK|ATF_DONTPUB)))
1168 if (!(r.arp_flags & ATF_NETMASK))
1169 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1170 htonl(0xFFFFFFFFUL);
1174 if ((dev = __dev_get_by_name(&init_net, r.arp_dev)) == NULL)
1177 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1178 if (!r.arp_ha.sa_family)
1179 r.arp_ha.sa_family = dev->type;
1181 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1183 } else if (cmd == SIOCGARP) {
1190 err = arp_req_delete(&r, dev);
1193 err = arp_req_set(&r, dev);
1196 err = arp_req_get(&r, dev);
1197 if (!err && copy_to_user(arg, &r, sizeof(r)))
1206 static int arp_netdev_event(struct notifier_block *this, unsigned long event, void *ptr)
1208 struct net_device *dev = ptr;
1210 if (dev->nd_net != &init_net)
1214 case NETDEV_CHANGEADDR:
1215 neigh_changeaddr(&arp_tbl, dev);
1225 static struct notifier_block arp_netdev_notifier = {
1226 .notifier_call = arp_netdev_event,
1229 /* Note, that it is not on notifier chain.
1230 It is necessary, that this routine was called after route cache will be
1233 void arp_ifdown(struct net_device *dev)
1235 neigh_ifdown(&arp_tbl, dev);
1240 * Called once on startup.
1243 static struct packet_type arp_packet_type = {
1244 .type = __constant_htons(ETH_P_ARP),
1248 static int arp_proc_init(void);
1250 void __init arp_init(void)
1252 neigh_table_init(&arp_tbl);
1254 dev_add_pack(&arp_packet_type);
1256 #ifdef CONFIG_SYSCTL
1257 neigh_sysctl_register(NULL, &arp_tbl.parms, NET_IPV4,
1258 NET_IPV4_NEIGH, "ipv4", NULL, NULL);
1260 register_netdevice_notifier(&arp_netdev_notifier);
1263 #ifdef CONFIG_PROC_FS
1264 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1266 /* ------------------------------------------------------------------------ */
1268 * ax25 -> ASCII conversion
1270 static char *ax2asc2(ax25_address *a, char *buf)
1275 for (n = 0, s = buf; n < 6; n++) {
1276 c = (a->ax25_call[n] >> 1) & 0x7F;
1278 if (c != ' ') *s++ = c;
1283 if ((n = ((a->ax25_call[6] >> 1) & 0x0F)) > 9) {
1291 if (*buf == '\0' || *buf == '-')
1297 #endif /* CONFIG_AX25 */
1299 #define HBUFFERLEN 30
1301 static void arp_format_neigh_entry(struct seq_file *seq,
1302 struct neighbour *n)
1304 char hbuffer[HBUFFERLEN];
1305 const char hexbuf[] = "0123456789ABCDEF";
1308 struct net_device *dev = n->dev;
1309 int hatype = dev->type;
1311 read_lock(&n->lock);
1312 /* Convert hardware address to XX:XX:XX:XX ... form. */
1313 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1314 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1315 ax2asc2((ax25_address *)n->ha, hbuffer);
1318 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1319 hbuffer[k++] = hexbuf[(n->ha[j] >> 4) & 15];
1320 hbuffer[k++] = hexbuf[n->ha[j] & 15];
1324 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1327 sprintf(tbuf, "%u.%u.%u.%u", NIPQUAD(*(u32*)n->primary_key));
1328 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1329 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1330 read_unlock(&n->lock);
1333 static void arp_format_pneigh_entry(struct seq_file *seq,
1334 struct pneigh_entry *n)
1336 struct net_device *dev = n->dev;
1337 int hatype = dev ? dev->type : 0;
1340 sprintf(tbuf, "%u.%u.%u.%u", NIPQUAD(*(u32*)n->key));
1341 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1342 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1343 dev ? dev->name : "*");
1346 static int arp_seq_show(struct seq_file *seq, void *v)
1348 if (v == SEQ_START_TOKEN) {
1349 seq_puts(seq, "IP address HW type Flags "
1350 "HW address Mask Device\n");
1352 struct neigh_seq_state *state = seq->private;
1354 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1355 arp_format_pneigh_entry(seq, v);
1357 arp_format_neigh_entry(seq, v);
1363 static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1365 /* Don't want to confuse "arp -a" w/ magic entries,
1366 * so we tell the generic iterator to skip NUD_NOARP.
1368 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1371 /* ------------------------------------------------------------------------ */
1373 static const struct seq_operations arp_seq_ops = {
1374 .start = arp_seq_start,
1375 .next = neigh_seq_next,
1376 .stop = neigh_seq_stop,
1377 .show = arp_seq_show,
1380 static int arp_seq_open(struct inode *inode, struct file *file)
1382 return seq_open_private(file, &arp_seq_ops,
1383 sizeof(struct neigh_seq_state));
1386 static const struct file_operations arp_seq_fops = {
1387 .owner = THIS_MODULE,
1388 .open = arp_seq_open,
1390 .llseek = seq_lseek,
1391 .release = seq_release_private,
1394 static int __init arp_proc_init(void)
1396 if (!proc_net_fops_create(&init_net, "arp", S_IRUGO, &arp_seq_fops))
1401 #else /* CONFIG_PROC_FS */
1403 static int __init arp_proc_init(void)
1408 #endif /* CONFIG_PROC_FS */
1410 EXPORT_SYMBOL(arp_broken_ops);
1411 EXPORT_SYMBOL(arp_find);
1412 EXPORT_SYMBOL(arp_create);
1413 EXPORT_SYMBOL(arp_xmit);
1414 EXPORT_SYMBOL(arp_send);
1415 EXPORT_SYMBOL(arp_tbl);
1417 #if defined(CONFIG_ATM_CLIP) || defined(CONFIG_ATM_CLIP_MODULE)
1418 EXPORT_SYMBOL(clip_tbl_hook);