1 /* linux/net/ipv4/arp.c
3 * Copyright (C) 1994 by Florian La Roche
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
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.
16 * Alan Cox : Removed the Ethernet assumptions in
18 * Alan Cox : Fixed some small errors in the ARP
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
42 * Russ Nelson : Tidied up a few bits.
43 * Alexey Kuznetsov: Major changes to caching and behaviour,
44 * eg intelligent arp probing and
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
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.
76 #include <linux/module.h>
77 #include <linux/types.h>
78 #include <linux/string.h>
79 #include <linux/kernel.h>
80 #include <linux/capability.h>
81 #include <linux/socket.h>
82 #include <linux/sockios.h>
83 #include <linux/errno.h>
86 #include <linux/inet.h>
87 #include <linux/inetdevice.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/seq_file.h>
96 #include <linux/stat.h>
97 #include <linux/init.h>
98 #include <linux/net.h>
99 #include <linux/rcupdate.h>
100 #include <linux/jhash.h>
101 #include <linux/slab.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 #include <net/ax25.h>
115 #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;
119 EXPORT_SYMBOL(clip_tbl_hook);
122 #include <asm/system.h>
123 #include <linux/uaccess.h>
125 #include <linux/netfilter_arp.h>
128 * Interface to generic neighbour cache.
130 static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 rnd);
131 static int arp_constructor(struct neighbour *neigh);
132 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
133 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
134 static void parp_redo(struct sk_buff *skb);
136 static const struct neigh_ops arp_generic_ops = {
138 .solicit = arp_solicit,
139 .error_report = arp_error_report,
140 .output = neigh_resolve_output,
141 .connected_output = neigh_connected_output,
142 .hh_output = dev_queue_xmit,
143 .queue_xmit = dev_queue_xmit,
146 static const struct neigh_ops arp_hh_ops = {
148 .solicit = arp_solicit,
149 .error_report = arp_error_report,
150 .output = neigh_resolve_output,
151 .connected_output = neigh_resolve_output,
152 .hh_output = dev_queue_xmit,
153 .queue_xmit = dev_queue_xmit,
156 static const struct neigh_ops arp_direct_ops = {
158 .output = dev_queue_xmit,
159 .connected_output = dev_queue_xmit,
160 .hh_output = dev_queue_xmit,
161 .queue_xmit = dev_queue_xmit,
164 static const struct neigh_ops arp_broken_ops = {
166 .solicit = arp_solicit,
167 .error_report = arp_error_report,
168 .output = neigh_compat_output,
169 .connected_output = neigh_compat_output,
170 .hh_output = dev_queue_xmit,
171 .queue_xmit = dev_queue_xmit,
174 struct neigh_table arp_tbl = {
176 .entry_size = sizeof(struct neighbour) + 4,
179 .constructor = arp_constructor,
180 .proxy_redo = parp_redo,
184 .base_reachable_time = 30 * HZ,
185 .retrans_time = 1 * HZ,
186 .gc_staletime = 60 * HZ,
187 .reachable_time = 30 * HZ,
188 .delay_probe_time = 5 * HZ,
192 .anycast_delay = 1 * HZ,
193 .proxy_delay = (8 * HZ) / 10,
197 .gc_interval = 30 * HZ,
202 EXPORT_SYMBOL(arp_tbl);
204 int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir)
210 ip_eth_mc_map(addr, haddr);
212 case ARPHRD_IEEE802_TR:
213 ip_tr_mc_map(addr, haddr);
215 case ARPHRD_INFINIBAND:
216 ip_ib_mc_map(addr, dev->broadcast, haddr);
220 memcpy(haddr, dev->broadcast, dev->addr_len);
228 static u32 arp_hash(const void *pkey,
229 const struct net_device *dev,
232 return jhash_2words(*(u32 *)pkey, dev->ifindex, 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;
243 in_dev = __in_dev_get_rcu(dev);
244 if (in_dev == NULL) {
249 neigh->type = inet_addr_type(dev_net(dev), addr);
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;
305 if (neigh->type == RTN_MULTICAST) {
306 neigh->nud_state = NUD_NOARP;
307 arp_mc_map(addr, neigh->ha, dev, 1);
308 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) {
309 neigh->nud_state = NUD_NOARP;
310 memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
311 } else if (neigh->type == RTN_BROADCAST ||
312 (dev->flags & IFF_POINTOPOINT)) {
313 neigh->nud_state = NUD_NOARP;
314 memcpy(neigh->ha, dev->broadcast, dev->addr_len);
317 if (dev->header_ops->cache)
318 neigh->ops = &arp_hh_ops;
320 neigh->ops = &arp_generic_ops;
322 if (neigh->nud_state & NUD_VALID)
323 neigh->output = neigh->ops->connected_output;
325 neigh->output = neigh->ops->output;
330 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
332 dst_link_failure(skb);
336 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
340 struct net_device *dev = neigh->dev;
341 __be32 target = *(__be32 *)neigh->primary_key;
342 int probes = atomic_read(&neigh->probes);
343 struct in_device *in_dev;
346 in_dev = __in_dev_get_rcu(dev);
351 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
353 case 0: /* By default announce any local IP */
354 if (skb && inet_addr_type(dev_net(dev),
355 ip_hdr(skb)->saddr) == RTN_LOCAL)
356 saddr = ip_hdr(skb)->saddr;
358 case 1: /* Restrict announcements of saddr in same subnet */
361 saddr = ip_hdr(skb)->saddr;
362 if (inet_addr_type(dev_net(dev), saddr) == RTN_LOCAL) {
363 /* saddr should be known to target */
364 if (inet_addr_onlink(in_dev, target, saddr))
369 case 2: /* Avoid secondary IPs, get a primary/preferred one */
375 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
377 probes -= neigh->parms->ucast_probes;
379 if (!(neigh->nud_state & NUD_VALID))
381 "trying to ucast probe in NUD_INVALID\n");
383 read_lock_bh(&neigh->lock);
385 probes -= neigh->parms->app_probes;
394 arp_send(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
395 dst_ha, dev->dev_addr, NULL);
397 read_unlock_bh(&neigh->lock);
400 static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip)
404 switch (IN_DEV_ARP_IGNORE(in_dev)) {
405 case 0: /* Reply, the tip is already validated */
407 case 1: /* Reply only if tip is configured on the incoming interface */
409 scope = RT_SCOPE_HOST;
412 * Reply only if tip is configured on the incoming interface
413 * and is in same subnet as sip
415 scope = RT_SCOPE_HOST;
417 case 3: /* Do not reply for scope host addresses */
419 scope = RT_SCOPE_LINK;
421 case 4: /* Reserved */
426 case 8: /* Do not reply */
431 return !inet_confirm_addr(in_dev, sip, tip, scope);
434 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
436 struct flowi fl = { .fl4_dst = sip,
440 /*unsigned long now; */
441 struct net *net = dev_net(dev);
443 rt = ip_route_output_key(net, &fl);
446 if (rt->dst.dev != dev) {
447 NET_INC_STATS_BH(net, LINUX_MIB_ARPFILTER);
454 /* OBSOLETE FUNCTIONS */
457 * Find an arp mapping in the cache. If not found, post a request.
459 * It is very UGLY routine: it DOES NOT use skb->dst->neighbour,
460 * even if it exists. It is supposed that skb->dev was mangled
461 * by a virtual device (eql, shaper). Nobody but broken devices
462 * is allowed to use this function, it is scheduled to be removed. --ANK
465 static int arp_set_predefined(int addr_hint, unsigned char *haddr,
466 __be32 paddr, struct net_device *dev)
470 printk(KERN_DEBUG "ARP: arp called for own IP address\n");
471 memcpy(haddr, dev->dev_addr, dev->addr_len);
474 arp_mc_map(paddr, haddr, dev, 1);
477 memcpy(haddr, dev->broadcast, dev->addr_len);
484 int arp_find(unsigned char *haddr, struct sk_buff *skb)
486 struct net_device *dev = skb->dev;
491 printk(KERN_DEBUG "arp_find is called with dst==NULL\n");
496 paddr = skb_rtable(skb)->rt_gateway;
498 if (arp_set_predefined(inet_addr_type(dev_net(dev), paddr), haddr,
502 n = __neigh_lookup(&arp_tbl, &paddr, dev, 1);
506 if (n->nud_state & NUD_VALID || neigh_event_send(n, skb) == 0) {
507 neigh_ha_snapshot(haddr, n, dev);
516 EXPORT_SYMBOL(arp_find);
518 /* END OF OBSOLETE FUNCTIONS */
520 int arp_bind_neighbour(struct dst_entry *dst)
522 struct net_device *dev = dst->dev;
523 struct neighbour *n = dst->neighbour;
528 __be32 nexthop = ((struct rtable *)dst)->rt_gateway;
529 if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT))
531 n = __neigh_lookup_errno(
532 #if defined(CONFIG_ATM_CLIP) || defined(CONFIG_ATM_CLIP_MODULE)
533 dev->type == ARPHRD_ATM ?
536 &arp_tbl, &nexthop, dev);
545 * Check if we can use proxy ARP for this path
547 static inline int arp_fwd_proxy(struct in_device *in_dev,
548 struct net_device *dev, struct rtable *rt)
550 struct in_device *out_dev;
553 if (rt->dst.dev == dev)
556 if (!IN_DEV_PROXY_ARP(in_dev))
558 imi = IN_DEV_MEDIUM_ID(in_dev);
564 /* place to check for proxy_arp for routes */
566 out_dev = __in_dev_get_rcu(rt->dst.dev);
568 omi = IN_DEV_MEDIUM_ID(out_dev);
570 return omi != imi && omi != -1;
574 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
576 * RFC3069 supports proxy arp replies back to the same interface. This
577 * is done to support (ethernet) switch features, like RFC 3069, where
578 * the individual ports are not allowed to communicate with each
579 * other, BUT they are allowed to talk to the upstream router. As
580 * described in RFC 3069, it is possible to allow these hosts to
581 * communicate through the upstream router, by proxy_arp'ing.
583 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
585 * This technology is known by different names:
586 * In RFC 3069 it is called VLAN Aggregation.
587 * Cisco and Allied Telesyn call it Private VLAN.
588 * Hewlett-Packard call it Source-Port filtering or port-isolation.
589 * Ericsson call it MAC-Forced Forwarding (RFC Draft).
592 static inline int arp_fwd_pvlan(struct in_device *in_dev,
593 struct net_device *dev, struct rtable *rt,
594 __be32 sip, __be32 tip)
596 /* Private VLAN is only concerned about the same ethernet segment */
597 if (rt->dst.dev != dev)
600 /* Don't reply on self probes (often done by windowz boxes)*/
604 if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
611 * Interface to link layer: send routine and receive handler.
615 * Create an arp packet. If (dest_hw == NULL), we create a broadcast
618 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
619 struct net_device *dev, __be32 src_ip,
620 const unsigned char *dest_hw,
621 const unsigned char *src_hw,
622 const unsigned char *target_hw)
626 unsigned char *arp_ptr;
632 skb = alloc_skb(arp_hdr_len(dev) + LL_ALLOCATED_SPACE(dev), GFP_ATOMIC);
636 skb_reserve(skb, LL_RESERVED_SPACE(dev));
637 skb_reset_network_header(skb);
638 arp = (struct arphdr *) skb_put(skb, arp_hdr_len(dev));
640 skb->protocol = htons(ETH_P_ARP);
642 src_hw = dev->dev_addr;
644 dest_hw = dev->broadcast;
647 * Fill the device header for the ARP frame
649 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
653 * Fill out the arp protocol part.
655 * The arp hardware type should match the device type, except for FDDI,
656 * which (according to RFC 1390) should always equal 1 (Ethernet).
659 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
660 * DIX code for the protocol. Make these device structure fields.
664 arp->ar_hrd = htons(dev->type);
665 arp->ar_pro = htons(ETH_P_IP);
668 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
670 arp->ar_hrd = htons(ARPHRD_AX25);
671 arp->ar_pro = htons(AX25_P_IP);
674 #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
676 arp->ar_hrd = htons(ARPHRD_NETROM);
677 arp->ar_pro = htons(AX25_P_IP);
682 #if defined(CONFIG_FDDI) || defined(CONFIG_FDDI_MODULE)
684 arp->ar_hrd = htons(ARPHRD_ETHER);
685 arp->ar_pro = htons(ETH_P_IP);
688 #if defined(CONFIG_TR) || defined(CONFIG_TR_MODULE)
689 case ARPHRD_IEEE802_TR:
690 arp->ar_hrd = htons(ARPHRD_IEEE802);
691 arp->ar_pro = htons(ETH_P_IP);
696 arp->ar_hln = dev->addr_len;
698 arp->ar_op = htons(type);
700 arp_ptr = (unsigned char *)(arp + 1);
702 memcpy(arp_ptr, src_hw, dev->addr_len);
703 arp_ptr += dev->addr_len;
704 memcpy(arp_ptr, &src_ip, 4);
706 if (target_hw != NULL)
707 memcpy(arp_ptr, target_hw, dev->addr_len);
709 memset(arp_ptr, 0, dev->addr_len);
710 arp_ptr += dev->addr_len;
711 memcpy(arp_ptr, &dest_ip, 4);
719 EXPORT_SYMBOL(arp_create);
722 * Send an arp packet.
724 void arp_xmit(struct sk_buff *skb)
726 /* Send it off, maybe filter it using firewalling first. */
727 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, skb, NULL, skb->dev, dev_queue_xmit);
729 EXPORT_SYMBOL(arp_xmit);
732 * Create and send an arp packet.
734 void arp_send(int type, int ptype, __be32 dest_ip,
735 struct net_device *dev, __be32 src_ip,
736 const unsigned char *dest_hw, const unsigned char *src_hw,
737 const unsigned char *target_hw)
742 * No arp on this interface.
745 if (dev->flags&IFF_NOARP)
748 skb = arp_create(type, ptype, dest_ip, dev, src_ip,
749 dest_hw, src_hw, target_hw);
755 EXPORT_SYMBOL(arp_send);
758 * Process an arp request.
761 static int arp_process(struct sk_buff *skb)
763 struct net_device *dev = skb->dev;
764 struct in_device *in_dev = __in_dev_get_rcu(dev);
766 unsigned char *arp_ptr;
770 u16 dev_type = dev->type;
773 struct net *net = dev_net(dev);
775 /* arp_rcv below verifies the ARP header and verifies the device
786 if (arp->ar_pro != htons(ETH_P_IP) ||
787 htons(dev_type) != arp->ar_hrd)
791 case ARPHRD_IEEE802_TR:
795 * ETHERNET, Token Ring and Fibre Channel (which are IEEE 802
796 * devices, according to RFC 2625) devices will accept ARP
797 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
798 * This is the case also of FDDI, where the RFC 1390 says that
799 * FDDI devices should accept ARP hardware of (1) Ethernet,
800 * however, to be more robust, we'll accept both 1 (Ethernet)
803 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
804 arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
805 arp->ar_pro != htons(ETH_P_IP))
809 if (arp->ar_pro != htons(AX25_P_IP) ||
810 arp->ar_hrd != htons(ARPHRD_AX25))
814 if (arp->ar_pro != htons(AX25_P_IP) ||
815 arp->ar_hrd != htons(ARPHRD_NETROM))
820 /* Understand only these message types */
822 if (arp->ar_op != htons(ARPOP_REPLY) &&
823 arp->ar_op != htons(ARPOP_REQUEST))
829 arp_ptr = (unsigned char *)(arp + 1);
831 arp_ptr += dev->addr_len;
832 memcpy(&sip, arp_ptr, 4);
834 arp_ptr += dev->addr_len;
835 memcpy(&tip, arp_ptr, 4);
837 * Check for bad requests for 127.x.x.x and requests for multicast
838 * addresses. If this is one such, delete it.
840 if (ipv4_is_loopback(tip) || ipv4_is_multicast(tip))
844 * Special case: We must set Frame Relay source Q.922 address
846 if (dev_type == ARPHRD_DLCI)
847 sha = dev->broadcast;
850 * Process entry. The idea here is we want to send a reply if it is a
851 * request for us or if it is a request for someone else that we hold
852 * a proxy for. We want to add an entry to our cache if it is a reply
853 * to us or if it is a request for our address.
854 * (The assumption for this last is that if someone is requesting our
855 * address, they are probably intending to talk to us, so it saves time
856 * if we cache their address. Their address is also probably not in
857 * our cache, since ours is not in their cache.)
859 * Putting this another way, we only care about replies if they are to
860 * us, in which case we add them to the cache. For requests, we care
861 * about those for us and those for our proxies. We reply to both,
862 * and in the case of requests for us we add the requester to the arp
866 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
868 if (arp->ar_op == htons(ARPOP_REQUEST) &&
869 inet_addr_type(net, tip) == RTN_LOCAL &&
870 !arp_ignore(in_dev, sip, tip))
871 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, sha,
876 if (arp->ar_op == htons(ARPOP_REQUEST) &&
877 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
879 rt = skb_rtable(skb);
880 addr_type = rt->rt_type;
882 if (addr_type == RTN_LOCAL) {
885 dont_send = arp_ignore(in_dev, sip, tip);
886 if (!dont_send && IN_DEV_ARPFILTER(in_dev))
887 dont_send = arp_filter(sip, tip, dev);
889 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
891 arp_send(ARPOP_REPLY, ETH_P_ARP, sip,
892 dev, tip, sha, dev->dev_addr,
898 } else if (IN_DEV_FORWARD(in_dev)) {
899 if (addr_type == RTN_UNICAST &&
900 (arp_fwd_proxy(in_dev, dev, rt) ||
901 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
902 pneigh_lookup(&arp_tbl, net, &tip, dev, 0))) {
903 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
907 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
908 skb->pkt_type == PACKET_HOST ||
909 in_dev->arp_parms->proxy_delay == 0) {
910 arp_send(ARPOP_REPLY, ETH_P_ARP, sip,
911 dev, tip, sha, dev->dev_addr,
914 pneigh_enqueue(&arp_tbl,
915 in_dev->arp_parms, skb);
923 /* Update our ARP tables */
925 n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
927 if (IPV4_DEVCONF_ALL(dev_net(dev), ARP_ACCEPT)) {
928 /* Unsolicited ARP is not accepted by default.
929 It is possible, that this option should be enabled for some
930 devices (strip is candidate)
933 (arp->ar_op == htons(ARPOP_REPLY) ||
934 (arp->ar_op == htons(ARPOP_REQUEST) && tip == sip)) &&
935 inet_addr_type(net, sip) == RTN_UNICAST)
936 n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
940 int state = NUD_REACHABLE;
943 /* If several different ARP replies follows back-to-back,
944 use the FIRST one. It is possible, if several proxy
945 agents are active. Taking the first reply prevents
946 arp trashing and chooses the fastest router.
948 override = time_after(jiffies, n->updated + n->parms->locktime);
950 /* Broadcast replies and request packets
951 do not assert neighbour reachability.
953 if (arp->ar_op != htons(ARPOP_REPLY) ||
954 skb->pkt_type != PACKET_HOST)
956 neigh_update(n, sha, state,
957 override ? NEIGH_UPDATE_F_OVERRIDE : 0);
966 static void parp_redo(struct sk_buff *skb)
973 * Receive an arp request from the device layer.
976 static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
977 struct packet_type *pt, struct net_device *orig_dev)
981 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
982 if (!pskb_may_pull(skb, arp_hdr_len(dev)))
986 if (arp->ar_hln != dev->addr_len ||
987 dev->flags & IFF_NOARP ||
988 skb->pkt_type == PACKET_OTHERHOST ||
989 skb->pkt_type == PACKET_LOOPBACK ||
993 skb = skb_share_check(skb, GFP_ATOMIC);
997 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
999 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, skb, dev, NULL, arp_process);
1008 * User level interface (ioctl)
1012 * Set (create) an ARP cache entry.
1015 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
1018 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
1021 if (__in_dev_get_rtnl(dev)) {
1022 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
1028 static int arp_req_set_public(struct net *net, struct arpreq *r,
1029 struct net_device *dev)
1031 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1032 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1034 if (mask && mask != htonl(0xFFFFFFFF))
1036 if (!dev && (r->arp_flags & ATF_COM)) {
1037 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family,
1043 if (pneigh_lookup(&arp_tbl, net, &ip, dev, 1) == NULL)
1048 return arp_req_set_proxy(net, dev, 1);
1051 static int arp_req_set(struct net *net, struct arpreq *r,
1052 struct net_device *dev)
1055 struct neighbour *neigh;
1058 if (r->arp_flags & ATF_PUBL)
1059 return arp_req_set_public(net, r, dev);
1061 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1062 if (r->arp_flags & ATF_PERM)
1063 r->arp_flags |= ATF_COM;
1065 struct flowi fl = { .fl4_dst = ip,
1066 .fl4_tos = RTO_ONLINK };
1067 struct rtable *rt = ip_route_output_key(net, &fl);
1076 switch (dev->type) {
1077 #if defined(CONFIG_FDDI) || defined(CONFIG_FDDI_MODULE)
1080 * According to RFC 1390, FDDI devices should accept ARP
1081 * hardware types of 1 (Ethernet). However, to be more
1082 * robust, we'll accept hardware types of either 1 (Ethernet)
1083 * or 6 (IEEE 802.2).
1085 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1086 r->arp_ha.sa_family != ARPHRD_ETHER &&
1087 r->arp_ha.sa_family != ARPHRD_IEEE802)
1092 if (r->arp_ha.sa_family != dev->type)
1097 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1098 err = PTR_ERR(neigh);
1099 if (!IS_ERR(neigh)) {
1100 unsigned state = NUD_STALE;
1101 if (r->arp_flags & ATF_PERM)
1102 state = NUD_PERMANENT;
1103 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ?
1104 r->arp_ha.sa_data : NULL, state,
1105 NEIGH_UPDATE_F_OVERRIDE |
1106 NEIGH_UPDATE_F_ADMIN);
1107 neigh_release(neigh);
1112 static unsigned arp_state_to_flags(struct neighbour *neigh)
1114 if (neigh->nud_state&NUD_PERMANENT)
1115 return ATF_PERM | ATF_COM;
1116 else if (neigh->nud_state&NUD_VALID)
1123 * Get an ARP cache entry.
1126 static int arp_req_get(struct arpreq *r, struct net_device *dev)
1128 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1129 struct neighbour *neigh;
1132 neigh = neigh_lookup(&arp_tbl, &ip, dev);
1134 read_lock_bh(&neigh->lock);
1135 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
1136 r->arp_flags = arp_state_to_flags(neigh);
1137 read_unlock_bh(&neigh->lock);
1138 r->arp_ha.sa_family = dev->type;
1139 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1140 neigh_release(neigh);
1146 int arp_invalidate(struct net_device *dev, __be32 ip)
1148 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
1152 if (neigh->nud_state & ~NUD_NOARP)
1153 err = neigh_update(neigh, NULL, NUD_FAILED,
1154 NEIGH_UPDATE_F_OVERRIDE|
1155 NEIGH_UPDATE_F_ADMIN);
1156 neigh_release(neigh);
1161 EXPORT_SYMBOL(arp_invalidate);
1163 static int arp_req_delete_public(struct net *net, struct arpreq *r,
1164 struct net_device *dev)
1166 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1167 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1169 if (mask == htonl(0xFFFFFFFF))
1170 return pneigh_delete(&arp_tbl, net, &ip, dev);
1175 return arp_req_set_proxy(net, dev, 0);
1178 static int arp_req_delete(struct net *net, struct arpreq *r,
1179 struct net_device *dev)
1183 if (r->arp_flags & ATF_PUBL)
1184 return arp_req_delete_public(net, r, dev);
1186 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1188 struct flowi fl = { .fl4_dst = ip,
1189 .fl4_tos = RTO_ONLINK };
1190 struct rtable *rt = ip_route_output_key(net, &fl);
1198 return arp_invalidate(dev, ip);
1202 * Handle an ARP layer I/O control request.
1205 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1209 struct net_device *dev = NULL;
1214 if (!capable(CAP_NET_ADMIN))
1217 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1225 if (r.arp_pa.sa_family != AF_INET)
1226 return -EPFNOSUPPORT;
1228 if (!(r.arp_flags & ATF_PUBL) &&
1229 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1231 if (!(r.arp_flags & ATF_NETMASK))
1232 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1233 htonl(0xFFFFFFFFUL);
1237 dev = __dev_get_by_name(net, r.arp_dev);
1241 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1242 if (!r.arp_ha.sa_family)
1243 r.arp_ha.sa_family = dev->type;
1245 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1247 } else if (cmd == SIOCGARP) {
1254 err = arp_req_delete(net, &r, dev);
1257 err = arp_req_set(net, &r, dev);
1260 err = arp_req_get(&r, dev);
1265 if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
1270 static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1273 struct net_device *dev = ptr;
1276 case NETDEV_CHANGEADDR:
1277 neigh_changeaddr(&arp_tbl, dev);
1278 rt_cache_flush(dev_net(dev), 0);
1287 static struct notifier_block arp_netdev_notifier = {
1288 .notifier_call = arp_netdev_event,
1291 /* Note, that it is not on notifier chain.
1292 It is necessary, that this routine was called after route cache will be
1295 void arp_ifdown(struct net_device *dev)
1297 neigh_ifdown(&arp_tbl, dev);
1302 * Called once on startup.
1305 static struct packet_type arp_packet_type __read_mostly = {
1306 .type = cpu_to_be16(ETH_P_ARP),
1310 static int arp_proc_init(void);
1312 void __init arp_init(void)
1314 neigh_table_init(&arp_tbl);
1316 dev_add_pack(&arp_packet_type);
1318 #ifdef CONFIG_SYSCTL
1319 neigh_sysctl_register(NULL, &arp_tbl.parms, "ipv4", NULL);
1321 register_netdevice_notifier(&arp_netdev_notifier);
1324 #ifdef CONFIG_PROC_FS
1325 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1327 /* ------------------------------------------------------------------------ */
1329 * ax25 -> ASCII conversion
1331 static char *ax2asc2(ax25_address *a, char *buf)
1336 for (n = 0, s = buf; n < 6; n++) {
1337 c = (a->ax25_call[n] >> 1) & 0x7F;
1344 n = (a->ax25_call[6] >> 1) & 0x0F;
1353 if (*buf == '\0' || *buf == '-')
1358 #endif /* CONFIG_AX25 */
1360 #define HBUFFERLEN 30
1362 static void arp_format_neigh_entry(struct seq_file *seq,
1363 struct neighbour *n)
1365 char hbuffer[HBUFFERLEN];
1368 struct net_device *dev = n->dev;
1369 int hatype = dev->type;
1371 read_lock(&n->lock);
1372 /* Convert hardware address to XX:XX:XX:XX ... form. */
1373 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1374 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1375 ax2asc2((ax25_address *)n->ha, hbuffer);
1378 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1379 hbuffer[k++] = hex_asc_hi(n->ha[j]);
1380 hbuffer[k++] = hex_asc_lo(n->ha[j]);
1386 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1389 sprintf(tbuf, "%pI4", n->primary_key);
1390 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1391 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1392 read_unlock(&n->lock);
1395 static void arp_format_pneigh_entry(struct seq_file *seq,
1396 struct pneigh_entry *n)
1398 struct net_device *dev = n->dev;
1399 int hatype = dev ? dev->type : 0;
1402 sprintf(tbuf, "%pI4", n->key);
1403 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1404 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1405 dev ? dev->name : "*");
1408 static int arp_seq_show(struct seq_file *seq, void *v)
1410 if (v == SEQ_START_TOKEN) {
1411 seq_puts(seq, "IP address HW type Flags "
1412 "HW address Mask Device\n");
1414 struct neigh_seq_state *state = seq->private;
1416 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1417 arp_format_pneigh_entry(seq, v);
1419 arp_format_neigh_entry(seq, v);
1425 static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1427 /* Don't want to confuse "arp -a" w/ magic entries,
1428 * so we tell the generic iterator to skip NUD_NOARP.
1430 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1433 /* ------------------------------------------------------------------------ */
1435 static const struct seq_operations arp_seq_ops = {
1436 .start = arp_seq_start,
1437 .next = neigh_seq_next,
1438 .stop = neigh_seq_stop,
1439 .show = arp_seq_show,
1442 static int arp_seq_open(struct inode *inode, struct file *file)
1444 return seq_open_net(inode, file, &arp_seq_ops,
1445 sizeof(struct neigh_seq_state));
1448 static const struct file_operations arp_seq_fops = {
1449 .owner = THIS_MODULE,
1450 .open = arp_seq_open,
1452 .llseek = seq_lseek,
1453 .release = seq_release_net,
1457 static int __net_init arp_net_init(struct net *net)
1459 if (!proc_net_fops_create(net, "arp", S_IRUGO, &arp_seq_fops))
1464 static void __net_exit arp_net_exit(struct net *net)
1466 proc_net_remove(net, "arp");
1469 static struct pernet_operations arp_net_ops = {
1470 .init = arp_net_init,
1471 .exit = arp_net_exit,
1474 static int __init arp_proc_init(void)
1476 return register_pernet_subsys(&arp_net_ops);
1479 #else /* CONFIG_PROC_FS */
1481 static int __init arp_proc_init(void)
1486 #endif /* CONFIG_PROC_FS */