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/slab.h>
102 #include <linux/sysctl.h>
105 #include <net/net_namespace.h>
107 #include <net/icmp.h>
108 #include <net/route.h>
109 #include <net/protocol.h>
111 #include <net/sock.h>
113 #include <net/ax25.h>
114 #include <net/netrom.h>
115 #if defined(CONFIG_ATM_CLIP) || defined(CONFIG_ATM_CLIP_MODULE)
116 #include <net/atmclip.h>
117 struct neigh_table *clip_tbl_hook;
118 EXPORT_SYMBOL(clip_tbl_hook);
121 #include <asm/system.h>
122 #include <linux/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, __u32 rnd);
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 const 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,
143 static const struct neigh_ops arp_hh_ops = {
145 .solicit = arp_solicit,
146 .error_report = arp_error_report,
147 .output = neigh_resolve_output,
148 .connected_output = neigh_resolve_output,
151 static const struct neigh_ops arp_direct_ops = {
153 .output = neigh_direct_output,
154 .connected_output = neigh_direct_output,
157 static const struct neigh_ops arp_broken_ops = {
159 .solicit = arp_solicit,
160 .error_report = arp_error_report,
161 .output = neigh_compat_output,
162 .connected_output = neigh_compat_output,
165 struct neigh_table arp_tbl = {
167 .entry_size = sizeof(struct neighbour) + 4,
170 .constructor = arp_constructor,
171 .proxy_redo = parp_redo,
175 .base_reachable_time = 30 * HZ,
176 .retrans_time = 1 * HZ,
177 .gc_staletime = 60 * HZ,
178 .reachable_time = 30 * HZ,
179 .delay_probe_time = 5 * HZ,
183 .anycast_delay = 1 * HZ,
184 .proxy_delay = (8 * HZ) / 10,
188 .gc_interval = 30 * HZ,
193 EXPORT_SYMBOL(arp_tbl);
195 int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir)
201 ip_eth_mc_map(addr, haddr);
203 case ARPHRD_IEEE802_TR:
204 ip_tr_mc_map(addr, haddr);
206 case ARPHRD_INFINIBAND:
207 ip_ib_mc_map(addr, dev->broadcast, haddr);
210 ip_ipgre_mc_map(addr, dev->broadcast, haddr);
214 memcpy(haddr, dev->broadcast, dev->addr_len);
222 static u32 arp_hash(const void *pkey,
223 const struct net_device *dev,
226 return arp_hashfn(*(u32 *)pkey, dev, hash_rnd);
229 static int arp_constructor(struct neighbour *neigh)
231 __be32 addr = *(__be32 *)neigh->primary_key;
232 struct net_device *dev = neigh->dev;
233 struct in_device *in_dev;
234 struct neigh_parms *parms;
237 in_dev = __in_dev_get_rcu(dev);
238 if (in_dev == NULL) {
243 neigh->type = inet_addr_type(dev_net(dev), addr);
245 parms = in_dev->arp_parms;
246 __neigh_parms_put(neigh->parms);
247 neigh->parms = neigh_parms_clone(parms);
250 if (!dev->header_ops) {
251 neigh->nud_state = NUD_NOARP;
252 neigh->ops = &arp_direct_ops;
253 neigh->output = neigh_direct_output;
255 /* Good devices (checked by reading texts, but only Ethernet is
258 ARPHRD_ETHER: (ethernet, apfddi)
261 ARPHRD_METRICOM: (strip)
265 ARPHRD_IPDDP will also work, if author repairs it.
266 I did not it, because this driver does not work even
271 /* So... these "amateur" devices are hopeless.
272 The only thing, that I can say now:
273 It is very sad that we need to keep ugly obsolete
274 code to make them happy.
276 They should be moved to more reasonable state, now
277 they use rebuild_header INSTEAD OF hard_start_xmit!!!
278 Besides that, they are sort of out of date
279 (a lot of redundant clones/copies, useless in 2.1),
280 I wonder why people believe that they work.
286 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
288 #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
291 neigh->ops = &arp_broken_ops;
292 neigh->output = neigh->ops->output;
299 if (neigh->type == RTN_MULTICAST) {
300 neigh->nud_state = NUD_NOARP;
301 arp_mc_map(addr, neigh->ha, dev, 1);
302 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) {
303 neigh->nud_state = NUD_NOARP;
304 memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
305 } else if (neigh->type == RTN_BROADCAST ||
306 (dev->flags & IFF_POINTOPOINT)) {
307 neigh->nud_state = NUD_NOARP;
308 memcpy(neigh->ha, dev->broadcast, dev->addr_len);
311 if (dev->header_ops->cache)
312 neigh->ops = &arp_hh_ops;
314 neigh->ops = &arp_generic_ops;
316 if (neigh->nud_state & NUD_VALID)
317 neigh->output = neigh->ops->connected_output;
319 neigh->output = neigh->ops->output;
324 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
326 dst_link_failure(skb);
330 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
334 struct net_device *dev = neigh->dev;
335 __be32 target = *(__be32 *)neigh->primary_key;
336 int probes = atomic_read(&neigh->probes);
337 struct in_device *in_dev;
340 in_dev = __in_dev_get_rcu(dev);
345 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
347 case 0: /* By default announce any local IP */
348 if (skb && inet_addr_type(dev_net(dev),
349 ip_hdr(skb)->saddr) == RTN_LOCAL)
350 saddr = ip_hdr(skb)->saddr;
352 case 1: /* Restrict announcements of saddr in same subnet */
355 saddr = ip_hdr(skb)->saddr;
356 if (inet_addr_type(dev_net(dev), saddr) == RTN_LOCAL) {
357 /* saddr should be known to target */
358 if (inet_addr_onlink(in_dev, target, saddr))
363 case 2: /* Avoid secondary IPs, get a primary/preferred one */
369 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
371 probes -= neigh->parms->ucast_probes;
373 if (!(neigh->nud_state & NUD_VALID))
375 "trying to ucast probe in NUD_INVALID\n");
377 read_lock_bh(&neigh->lock);
379 probes -= neigh->parms->app_probes;
388 arp_send(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
389 dst_ha, dev->dev_addr, NULL);
391 read_unlock_bh(&neigh->lock);
394 static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip)
398 switch (IN_DEV_ARP_IGNORE(in_dev)) {
399 case 0: /* Reply, the tip is already validated */
401 case 1: /* Reply only if tip is configured on the incoming interface */
403 scope = RT_SCOPE_HOST;
406 * Reply only if tip is configured on the incoming interface
407 * and is in same subnet as sip
409 scope = RT_SCOPE_HOST;
411 case 3: /* Do not reply for scope host addresses */
413 scope = RT_SCOPE_LINK;
415 case 4: /* Reserved */
420 case 8: /* Do not reply */
425 return !inet_confirm_addr(in_dev, sip, tip, scope);
428 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
432 /*unsigned long now; */
433 struct net *net = dev_net(dev);
435 rt = ip_route_output(net, sip, tip, 0, 0);
438 if (rt->dst.dev != dev) {
439 NET_INC_STATS_BH(net, LINUX_MIB_ARPFILTER);
446 /* OBSOLETE FUNCTIONS */
449 * Find an arp mapping in the cache. If not found, post a request.
451 * It is very UGLY routine: it DOES NOT use skb->dst->neighbour,
452 * even if it exists. It is supposed that skb->dev was mangled
453 * by a virtual device (eql, shaper). Nobody but broken devices
454 * is allowed to use this function, it is scheduled to be removed. --ANK
457 static int arp_set_predefined(int addr_hint, unsigned char *haddr,
458 __be32 paddr, struct net_device *dev)
462 printk(KERN_DEBUG "ARP: arp called for own IP address\n");
463 memcpy(haddr, dev->dev_addr, dev->addr_len);
466 arp_mc_map(paddr, haddr, dev, 1);
469 memcpy(haddr, dev->broadcast, dev->addr_len);
476 int arp_find(unsigned char *haddr, struct sk_buff *skb)
478 struct net_device *dev = skb->dev;
483 printk(KERN_DEBUG "arp_find is called with dst==NULL\n");
488 paddr = skb_rtable(skb)->rt_gateway;
490 if (arp_set_predefined(inet_addr_type(dev_net(dev), paddr), haddr,
494 n = __neigh_lookup(&arp_tbl, &paddr, dev, 1);
498 if (n->nud_state & NUD_VALID || neigh_event_send(n, skb) == 0) {
499 neigh_ha_snapshot(haddr, n, dev);
508 EXPORT_SYMBOL(arp_find);
510 /* END OF OBSOLETE FUNCTIONS */
513 * Check if we can use proxy ARP for this path
515 static inline int arp_fwd_proxy(struct in_device *in_dev,
516 struct net_device *dev, struct rtable *rt)
518 struct in_device *out_dev;
521 if (rt->dst.dev == dev)
524 if (!IN_DEV_PROXY_ARP(in_dev))
526 imi = IN_DEV_MEDIUM_ID(in_dev);
532 /* place to check for proxy_arp for routes */
534 out_dev = __in_dev_get_rcu(rt->dst.dev);
536 omi = IN_DEV_MEDIUM_ID(out_dev);
538 return omi != imi && omi != -1;
542 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
544 * RFC3069 supports proxy arp replies back to the same interface. This
545 * is done to support (ethernet) switch features, like RFC 3069, where
546 * the individual ports are not allowed to communicate with each
547 * other, BUT they are allowed to talk to the upstream router. As
548 * described in RFC 3069, it is possible to allow these hosts to
549 * communicate through the upstream router, by proxy_arp'ing.
551 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
553 * This technology is known by different names:
554 * In RFC 3069 it is called VLAN Aggregation.
555 * Cisco and Allied Telesyn call it Private VLAN.
556 * Hewlett-Packard call it Source-Port filtering or port-isolation.
557 * Ericsson call it MAC-Forced Forwarding (RFC Draft).
560 static inline int arp_fwd_pvlan(struct in_device *in_dev,
561 struct net_device *dev, struct rtable *rt,
562 __be32 sip, __be32 tip)
564 /* Private VLAN is only concerned about the same ethernet segment */
565 if (rt->dst.dev != dev)
568 /* Don't reply on self probes (often done by windowz boxes)*/
572 if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
579 * Interface to link layer: send routine and receive handler.
583 * Create an arp packet. If (dest_hw == NULL), we create a broadcast
586 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
587 struct net_device *dev, __be32 src_ip,
588 const unsigned char *dest_hw,
589 const unsigned char *src_hw,
590 const unsigned char *target_hw)
594 unsigned char *arp_ptr;
595 int hlen = LL_RESERVED_SPACE(dev);
596 int tlen = dev->needed_tailroom;
602 skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
606 skb_reserve(skb, hlen);
607 skb_reset_network_header(skb);
608 arp = (struct arphdr *) skb_put(skb, arp_hdr_len(dev));
610 skb->protocol = htons(ETH_P_ARP);
612 src_hw = dev->dev_addr;
614 dest_hw = dev->broadcast;
617 * Fill the device header for the ARP frame
619 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
623 * Fill out the arp protocol part.
625 * The arp hardware type should match the device type, except for FDDI,
626 * which (according to RFC 1390) should always equal 1 (Ethernet).
629 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
630 * DIX code for the protocol. Make these device structure fields.
634 arp->ar_hrd = htons(dev->type);
635 arp->ar_pro = htons(ETH_P_IP);
638 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
640 arp->ar_hrd = htons(ARPHRD_AX25);
641 arp->ar_pro = htons(AX25_P_IP);
644 #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
646 arp->ar_hrd = htons(ARPHRD_NETROM);
647 arp->ar_pro = htons(AX25_P_IP);
652 #if defined(CONFIG_FDDI) || defined(CONFIG_FDDI_MODULE)
654 arp->ar_hrd = htons(ARPHRD_ETHER);
655 arp->ar_pro = htons(ETH_P_IP);
658 #if defined(CONFIG_TR) || defined(CONFIG_TR_MODULE)
659 case ARPHRD_IEEE802_TR:
660 arp->ar_hrd = htons(ARPHRD_IEEE802);
661 arp->ar_pro = htons(ETH_P_IP);
666 arp->ar_hln = dev->addr_len;
668 arp->ar_op = htons(type);
670 arp_ptr = (unsigned char *)(arp + 1);
672 memcpy(arp_ptr, src_hw, dev->addr_len);
673 arp_ptr += dev->addr_len;
674 memcpy(arp_ptr, &src_ip, 4);
676 if (target_hw != NULL)
677 memcpy(arp_ptr, target_hw, dev->addr_len);
679 memset(arp_ptr, 0, dev->addr_len);
680 arp_ptr += dev->addr_len;
681 memcpy(arp_ptr, &dest_ip, 4);
689 EXPORT_SYMBOL(arp_create);
692 * Send an arp packet.
694 void arp_xmit(struct sk_buff *skb)
696 /* Send it off, maybe filter it using firewalling first. */
697 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, skb, NULL, skb->dev, dev_queue_xmit);
699 EXPORT_SYMBOL(arp_xmit);
702 * Create and send an arp packet.
704 void arp_send(int type, int ptype, __be32 dest_ip,
705 struct net_device *dev, __be32 src_ip,
706 const unsigned char *dest_hw, const unsigned char *src_hw,
707 const unsigned char *target_hw)
712 * No arp on this interface.
715 if (dev->flags&IFF_NOARP)
718 skb = arp_create(type, ptype, dest_ip, dev, src_ip,
719 dest_hw, src_hw, target_hw);
725 EXPORT_SYMBOL(arp_send);
728 * Process an arp request.
731 static int arp_process(struct sk_buff *skb)
733 struct net_device *dev = skb->dev;
734 struct in_device *in_dev = __in_dev_get_rcu(dev);
736 unsigned char *arp_ptr;
740 u16 dev_type = dev->type;
743 struct net *net = dev_net(dev);
745 /* arp_rcv below verifies the ARP header and verifies the device
756 if (arp->ar_pro != htons(ETH_P_IP) ||
757 htons(dev_type) != arp->ar_hrd)
761 case ARPHRD_IEEE802_TR:
765 * ETHERNET, Token Ring and Fibre Channel (which are IEEE 802
766 * devices, according to RFC 2625) devices will accept ARP
767 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
768 * This is the case also of FDDI, where the RFC 1390 says that
769 * FDDI devices should accept ARP hardware of (1) Ethernet,
770 * however, to be more robust, we'll accept both 1 (Ethernet)
773 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
774 arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
775 arp->ar_pro != htons(ETH_P_IP))
779 if (arp->ar_pro != htons(AX25_P_IP) ||
780 arp->ar_hrd != htons(ARPHRD_AX25))
784 if (arp->ar_pro != htons(AX25_P_IP) ||
785 arp->ar_hrd != htons(ARPHRD_NETROM))
790 /* Understand only these message types */
792 if (arp->ar_op != htons(ARPOP_REPLY) &&
793 arp->ar_op != htons(ARPOP_REQUEST))
799 arp_ptr = (unsigned char *)(arp + 1);
801 arp_ptr += dev->addr_len;
802 memcpy(&sip, arp_ptr, 4);
804 arp_ptr += dev->addr_len;
805 memcpy(&tip, arp_ptr, 4);
807 * Check for bad requests for 127.x.x.x and requests for multicast
808 * addresses. If this is one such, delete it.
810 if (ipv4_is_loopback(tip) || ipv4_is_multicast(tip))
814 * Special case: We must set Frame Relay source Q.922 address
816 if (dev_type == ARPHRD_DLCI)
817 sha = dev->broadcast;
820 * Process entry. The idea here is we want to send a reply if it is a
821 * request for us or if it is a request for someone else that we hold
822 * a proxy for. We want to add an entry to our cache if it is a reply
823 * to us or if it is a request for our address.
824 * (The assumption for this last is that if someone is requesting our
825 * address, they are probably intending to talk to us, so it saves time
826 * if we cache their address. Their address is also probably not in
827 * our cache, since ours is not in their cache.)
829 * Putting this another way, we only care about replies if they are to
830 * us, in which case we add them to the cache. For requests, we care
831 * about those for us and those for our proxies. We reply to both,
832 * and in the case of requests for us we add the requester to the arp
836 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
838 if (arp->ar_op == htons(ARPOP_REQUEST) &&
839 inet_addr_type(net, tip) == RTN_LOCAL &&
840 !arp_ignore(in_dev, sip, tip))
841 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, sha,
846 if (arp->ar_op == htons(ARPOP_REQUEST) &&
847 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
849 rt = skb_rtable(skb);
850 addr_type = rt->rt_type;
852 if (addr_type == RTN_LOCAL) {
855 dont_send = arp_ignore(in_dev, sip, tip);
856 if (!dont_send && IN_DEV_ARPFILTER(in_dev))
857 dont_send = arp_filter(sip, tip, dev);
859 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
861 arp_send(ARPOP_REPLY, ETH_P_ARP, sip,
862 dev, tip, sha, dev->dev_addr,
868 } else if (IN_DEV_FORWARD(in_dev)) {
869 if (addr_type == RTN_UNICAST &&
870 (arp_fwd_proxy(in_dev, dev, rt) ||
871 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
872 (rt->dst.dev != dev &&
873 pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
874 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
878 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
879 skb->pkt_type == PACKET_HOST ||
880 in_dev->arp_parms->proxy_delay == 0) {
881 arp_send(ARPOP_REPLY, ETH_P_ARP, sip,
882 dev, tip, sha, dev->dev_addr,
885 pneigh_enqueue(&arp_tbl,
886 in_dev->arp_parms, skb);
894 /* Update our ARP tables */
896 n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
898 if (IPV4_DEVCONF_ALL(dev_net(dev), ARP_ACCEPT)) {
899 /* Unsolicited ARP is not accepted by default.
900 It is possible, that this option should be enabled for some
901 devices (strip is candidate)
904 (arp->ar_op == htons(ARPOP_REPLY) ||
905 (arp->ar_op == htons(ARPOP_REQUEST) && tip == sip)) &&
906 inet_addr_type(net, sip) == RTN_UNICAST)
907 n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
911 int state = NUD_REACHABLE;
914 /* If several different ARP replies follows back-to-back,
915 use the FIRST one. It is possible, if several proxy
916 agents are active. Taking the first reply prevents
917 arp trashing and chooses the fastest router.
919 override = time_after(jiffies, n->updated + n->parms->locktime);
921 /* Broadcast replies and request packets
922 do not assert neighbour reachability.
924 if (arp->ar_op != htons(ARPOP_REPLY) ||
925 skb->pkt_type != PACKET_HOST)
927 neigh_update(n, sha, state,
928 override ? NEIGH_UPDATE_F_OVERRIDE : 0);
937 static void parp_redo(struct sk_buff *skb)
944 * Receive an arp request from the device layer.
947 static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
948 struct packet_type *pt, struct net_device *orig_dev)
952 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
953 if (!pskb_may_pull(skb, arp_hdr_len(dev)))
957 if (arp->ar_hln != dev->addr_len ||
958 dev->flags & IFF_NOARP ||
959 skb->pkt_type == PACKET_OTHERHOST ||
960 skb->pkt_type == PACKET_LOOPBACK ||
964 skb = skb_share_check(skb, GFP_ATOMIC);
968 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
970 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, skb, dev, NULL, arp_process);
979 * User level interface (ioctl)
983 * Set (create) an ARP cache entry.
986 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
989 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
992 if (__in_dev_get_rtnl(dev)) {
993 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
999 static int arp_req_set_public(struct net *net, struct arpreq *r,
1000 struct net_device *dev)
1002 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1003 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1005 if (mask && mask != htonl(0xFFFFFFFF))
1007 if (!dev && (r->arp_flags & ATF_COM)) {
1008 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family,
1014 if (pneigh_lookup(&arp_tbl, net, &ip, dev, 1) == NULL)
1019 return arp_req_set_proxy(net, dev, 1);
1022 static int arp_req_set(struct net *net, struct arpreq *r,
1023 struct net_device *dev)
1026 struct neighbour *neigh;
1029 if (r->arp_flags & ATF_PUBL)
1030 return arp_req_set_public(net, r, dev);
1032 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1033 if (r->arp_flags & ATF_PERM)
1034 r->arp_flags |= ATF_COM;
1036 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1045 switch (dev->type) {
1046 #if defined(CONFIG_FDDI) || defined(CONFIG_FDDI_MODULE)
1049 * According to RFC 1390, FDDI devices should accept ARP
1050 * hardware types of 1 (Ethernet). However, to be more
1051 * robust, we'll accept hardware types of either 1 (Ethernet)
1052 * or 6 (IEEE 802.2).
1054 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1055 r->arp_ha.sa_family != ARPHRD_ETHER &&
1056 r->arp_ha.sa_family != ARPHRD_IEEE802)
1061 if (r->arp_ha.sa_family != dev->type)
1066 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1067 err = PTR_ERR(neigh);
1068 if (!IS_ERR(neigh)) {
1069 unsigned state = NUD_STALE;
1070 if (r->arp_flags & ATF_PERM)
1071 state = NUD_PERMANENT;
1072 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ?
1073 r->arp_ha.sa_data : NULL, state,
1074 NEIGH_UPDATE_F_OVERRIDE |
1075 NEIGH_UPDATE_F_ADMIN);
1076 neigh_release(neigh);
1081 static unsigned arp_state_to_flags(struct neighbour *neigh)
1083 if (neigh->nud_state&NUD_PERMANENT)
1084 return ATF_PERM | ATF_COM;
1085 else if (neigh->nud_state&NUD_VALID)
1092 * Get an ARP cache entry.
1095 static int arp_req_get(struct arpreq *r, struct net_device *dev)
1097 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1098 struct neighbour *neigh;
1101 neigh = neigh_lookup(&arp_tbl, &ip, dev);
1103 read_lock_bh(&neigh->lock);
1104 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
1105 r->arp_flags = arp_state_to_flags(neigh);
1106 read_unlock_bh(&neigh->lock);
1107 r->arp_ha.sa_family = dev->type;
1108 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1109 neigh_release(neigh);
1115 int arp_invalidate(struct net_device *dev, __be32 ip)
1117 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
1121 if (neigh->nud_state & ~NUD_NOARP)
1122 err = neigh_update(neigh, NULL, NUD_FAILED,
1123 NEIGH_UPDATE_F_OVERRIDE|
1124 NEIGH_UPDATE_F_ADMIN);
1125 neigh_release(neigh);
1130 EXPORT_SYMBOL(arp_invalidate);
1132 static int arp_req_delete_public(struct net *net, struct arpreq *r,
1133 struct net_device *dev)
1135 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1136 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1138 if (mask == htonl(0xFFFFFFFF))
1139 return pneigh_delete(&arp_tbl, net, &ip, dev);
1144 return arp_req_set_proxy(net, dev, 0);
1147 static int arp_req_delete(struct net *net, struct arpreq *r,
1148 struct net_device *dev)
1152 if (r->arp_flags & ATF_PUBL)
1153 return arp_req_delete_public(net, r, dev);
1155 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1157 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1165 return arp_invalidate(dev, ip);
1169 * Handle an ARP layer I/O control request.
1172 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1176 struct net_device *dev = NULL;
1181 if (!capable(CAP_NET_ADMIN))
1184 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1192 if (r.arp_pa.sa_family != AF_INET)
1193 return -EPFNOSUPPORT;
1195 if (!(r.arp_flags & ATF_PUBL) &&
1196 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1198 if (!(r.arp_flags & ATF_NETMASK))
1199 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1200 htonl(0xFFFFFFFFUL);
1204 dev = __dev_get_by_name(net, r.arp_dev);
1208 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1209 if (!r.arp_ha.sa_family)
1210 r.arp_ha.sa_family = dev->type;
1212 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1214 } else if (cmd == SIOCGARP) {
1221 err = arp_req_delete(net, &r, dev);
1224 err = arp_req_set(net, &r, dev);
1227 err = arp_req_get(&r, dev);
1232 if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
1237 static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1240 struct net_device *dev = ptr;
1243 case NETDEV_CHANGEADDR:
1244 neigh_changeaddr(&arp_tbl, dev);
1245 rt_cache_flush(dev_net(dev), 0);
1254 static struct notifier_block arp_netdev_notifier = {
1255 .notifier_call = arp_netdev_event,
1258 /* Note, that it is not on notifier chain.
1259 It is necessary, that this routine was called after route cache will be
1262 void arp_ifdown(struct net_device *dev)
1264 neigh_ifdown(&arp_tbl, dev);
1269 * Called once on startup.
1272 static struct packet_type arp_packet_type __read_mostly = {
1273 .type = cpu_to_be16(ETH_P_ARP),
1277 static int arp_proc_init(void);
1279 void __init arp_init(void)
1281 neigh_table_init(&arp_tbl);
1283 dev_add_pack(&arp_packet_type);
1285 #ifdef CONFIG_SYSCTL
1286 neigh_sysctl_register(NULL, &arp_tbl.parms, "ipv4", NULL);
1288 register_netdevice_notifier(&arp_netdev_notifier);
1291 #ifdef CONFIG_PROC_FS
1292 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1294 /* ------------------------------------------------------------------------ */
1296 * ax25 -> ASCII conversion
1298 static char *ax2asc2(ax25_address *a, char *buf)
1303 for (n = 0, s = buf; n < 6; n++) {
1304 c = (a->ax25_call[n] >> 1) & 0x7F;
1311 n = (a->ax25_call[6] >> 1) & 0x0F;
1320 if (*buf == '\0' || *buf == '-')
1325 #endif /* CONFIG_AX25 */
1327 #define HBUFFERLEN 30
1329 static void arp_format_neigh_entry(struct seq_file *seq,
1330 struct neighbour *n)
1332 char hbuffer[HBUFFERLEN];
1335 struct net_device *dev = n->dev;
1336 int hatype = dev->type;
1338 read_lock(&n->lock);
1339 /* Convert hardware address to XX:XX:XX:XX ... form. */
1340 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1341 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1342 ax2asc2((ax25_address *)n->ha, hbuffer);
1345 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1346 hbuffer[k++] = hex_asc_hi(n->ha[j]);
1347 hbuffer[k++] = hex_asc_lo(n->ha[j]);
1353 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1356 sprintf(tbuf, "%pI4", n->primary_key);
1357 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1358 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1359 read_unlock(&n->lock);
1362 static void arp_format_pneigh_entry(struct seq_file *seq,
1363 struct pneigh_entry *n)
1365 struct net_device *dev = n->dev;
1366 int hatype = dev ? dev->type : 0;
1369 sprintf(tbuf, "%pI4", n->key);
1370 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1371 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1372 dev ? dev->name : "*");
1375 static int arp_seq_show(struct seq_file *seq, void *v)
1377 if (v == SEQ_START_TOKEN) {
1378 seq_puts(seq, "IP address HW type Flags "
1379 "HW address Mask Device\n");
1381 struct neigh_seq_state *state = seq->private;
1383 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1384 arp_format_pneigh_entry(seq, v);
1386 arp_format_neigh_entry(seq, v);
1392 static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1394 /* Don't want to confuse "arp -a" w/ magic entries,
1395 * so we tell the generic iterator to skip NUD_NOARP.
1397 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1400 /* ------------------------------------------------------------------------ */
1402 static const struct seq_operations arp_seq_ops = {
1403 .start = arp_seq_start,
1404 .next = neigh_seq_next,
1405 .stop = neigh_seq_stop,
1406 .show = arp_seq_show,
1409 static int arp_seq_open(struct inode *inode, struct file *file)
1411 return seq_open_net(inode, file, &arp_seq_ops,
1412 sizeof(struct neigh_seq_state));
1415 static const struct file_operations arp_seq_fops = {
1416 .owner = THIS_MODULE,
1417 .open = arp_seq_open,
1419 .llseek = seq_lseek,
1420 .release = seq_release_net,
1424 static int __net_init arp_net_init(struct net *net)
1426 if (!proc_net_fops_create(net, "arp", S_IRUGO, &arp_seq_fops))
1431 static void __net_exit arp_net_exit(struct net *net)
1433 proc_net_remove(net, "arp");
1436 static struct pernet_operations arp_net_ops = {
1437 .init = arp_net_init,
1438 .exit = arp_net_exit,
1441 static int __init arp_proc_init(void)
1443 return register_pernet_subsys(&arp_net_ops);
1446 #else /* CONFIG_PROC_FS */
1448 static int __init arp_proc_init(void)
1453 #endif /* CONFIG_PROC_FS */