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 * 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).
76 #include <linux/module.h>
77 #include <linux/types.h>
78 #include <linux/string.h>
79 #include <linux/kernel.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/seq_file.h>
96 #include <linux/stat.h>
97 #include <linux/init.h>
98 #include <linux/net.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)
227 hash_val = *(u32*)pkey;
228 hash_val ^= (hash_val>>16);
229 hash_val ^= hash_val>>8;
230 hash_val ^= hash_val>>3;
231 hash_val = (hash_val^dev->ifindex)&NEIGH_HASHMASK;
236 static int arp_constructor(struct neighbour *neigh)
238 u32 addr = *(u32*)neigh->primary_key;
239 struct net_device *dev = neigh->dev;
240 struct in_device *in_dev = in_dev_get(dev);
245 neigh->type = inet_addr_type(addr);
246 if (in_dev->arp_parms)
247 neigh->parms = in_dev->arp_parms;
251 if (dev->hard_header == NULL) {
252 neigh->nud_state = NUD_NOARP;
253 neigh->ops = &arp_direct_ops;
254 neigh->output = neigh->ops->queue_xmit;
256 /* Good devices (checked by reading texts, but only Ethernet is
259 ARPHRD_ETHER: (ethernet, apfddi)
262 ARPHRD_METRICOM: (strip)
266 ARPHRD_IPDDP will also work, if author repairs it.
267 I did not it, because this driver does not work even
272 /* So... these "amateur" devices are hopeless.
273 The only thing, that I can say now:
274 It is very sad that we need to keep ugly obsolete
275 code to make them happy.
277 They should be moved to more reasonable state, now
278 they use rebuild_header INSTEAD OF hard_start_xmit!!!
279 Besides that, they are sort of out of date
280 (a lot of redundant clones/copies, useless in 2.1),
281 I wonder why people believe that they work.
287 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
289 #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
292 neigh->ops = &arp_broken_ops;
293 neigh->output = neigh->ops->output;
298 if (neigh->type == RTN_MULTICAST) {
299 neigh->nud_state = NUD_NOARP;
300 arp_mc_map(addr, neigh->ha, dev, 1);
301 } else if (dev->flags&(IFF_NOARP|IFF_LOOPBACK)) {
302 neigh->nud_state = NUD_NOARP;
303 memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
304 } else if (neigh->type == RTN_BROADCAST || dev->flags&IFF_POINTOPOINT) {
305 neigh->nud_state = NUD_NOARP;
306 memcpy(neigh->ha, dev->broadcast, dev->addr_len);
308 if (dev->hard_header_cache)
309 neigh->ops = &arp_hh_ops;
311 neigh->ops = &arp_generic_ops;
312 if (neigh->nud_state&NUD_VALID)
313 neigh->output = neigh->ops->connected_output;
315 neigh->output = neigh->ops->output;
320 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
322 dst_link_failure(skb);
326 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
330 struct net_device *dev = neigh->dev;
331 u32 target = *(u32*)neigh->primary_key;
332 int probes = atomic_read(&neigh->probes);
333 struct in_device *in_dev = in_dev_get(dev);
338 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
340 case 0: /* By default announce any local IP */
341 if (skb && inet_addr_type(skb->nh.iph->saddr) == RTN_LOCAL)
342 saddr = skb->nh.iph->saddr;
344 case 1: /* Restrict announcements of saddr in same subnet */
347 saddr = skb->nh.iph->saddr;
348 if (inet_addr_type(saddr) == RTN_LOCAL) {
349 /* saddr should be known to target */
350 if (inet_addr_onlink(in_dev, target, saddr))
355 case 2: /* Avoid secondary IPs, get a primary/preferred one */
362 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
364 if ((probes -= neigh->parms->ucast_probes) < 0) {
365 if (!(neigh->nud_state&NUD_VALID))
366 printk(KERN_DEBUG "trying to ucast probe in NUD_INVALID\n");
368 read_lock_bh(&neigh->lock);
369 } else if ((probes -= neigh->parms->app_probes) < 0) {
376 arp_send(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
377 dst_ha, dev->dev_addr, NULL);
379 read_unlock_bh(&neigh->lock);
382 static int arp_ignore(struct in_device *in_dev, struct net_device *dev,
387 switch (IN_DEV_ARP_IGNORE(in_dev)) {
388 case 0: /* Reply, the tip is already validated */
390 case 1: /* Reply only if tip is configured on the incoming interface */
392 scope = RT_SCOPE_HOST;
395 * Reply only if tip is configured on the incoming interface
396 * and is in same subnet as sip
398 scope = RT_SCOPE_HOST;
400 case 3: /* Do not reply for scope host addresses */
402 scope = RT_SCOPE_LINK;
405 case 4: /* Reserved */
410 case 8: /* Do not reply */
415 return !inet_confirm_addr(dev, sip, tip, scope);
418 static int arp_filter(__u32 sip, __u32 tip, struct net_device *dev)
420 struct flowi fl = { .nl_u = { .ip4_u = { .daddr = sip,
424 /*unsigned long now; */
426 if (ip_route_output_key(&rt, &fl) < 0)
428 if (rt->u.dst.dev != dev) {
429 NET_INC_STATS_BH(ArpFilter);
436 /* OBSOLETE FUNCTIONS */
439 * Find an arp mapping in the cache. If not found, post a request.
441 * It is very UGLY routine: it DOES NOT use skb->dst->neighbour,
442 * even if it exists. It is supposed that skb->dev was mangled
443 * by a virtual device (eql, shaper). Nobody but broken devices
444 * is allowed to use this function, it is scheduled to be removed. --ANK
447 static int arp_set_predefined(int addr_hint, unsigned char * haddr, u32 paddr, struct net_device * dev)
451 printk(KERN_DEBUG "ARP: arp called for own IP address\n");
452 memcpy(haddr, dev->dev_addr, dev->addr_len);
455 arp_mc_map(paddr, haddr, dev, 1);
458 memcpy(haddr, dev->broadcast, dev->addr_len);
465 int arp_find(unsigned char *haddr, struct sk_buff *skb)
467 struct net_device *dev = skb->dev;
472 printk(KERN_DEBUG "arp_find is called with dst==NULL\n");
477 paddr = ((struct rtable*)skb->dst)->rt_gateway;
479 if (arp_set_predefined(inet_addr_type(paddr), haddr, paddr, dev))
482 n = __neigh_lookup(&arp_tbl, &paddr, dev, 1);
486 if (n->nud_state&NUD_VALID || neigh_event_send(n, skb) == 0) {
487 read_lock_bh(&n->lock);
488 memcpy(haddr, n->ha, dev->addr_len);
489 read_unlock_bh(&n->lock);
499 /* END OF OBSOLETE FUNCTIONS */
501 int arp_bind_neighbour(struct dst_entry *dst)
503 struct net_device *dev = dst->dev;
504 struct neighbour *n = dst->neighbour;
509 u32 nexthop = ((struct rtable*)dst)->rt_gateway;
510 if (dev->flags&(IFF_LOOPBACK|IFF_POINTOPOINT))
512 n = __neigh_lookup_errno(
513 #if defined(CONFIG_ATM_CLIP) || defined(CONFIG_ATM_CLIP_MODULE)
514 dev->type == ARPHRD_ATM ? clip_tbl_hook :
516 &arp_tbl, &nexthop, dev);
525 * Check if we can use proxy ARP for this path
528 static inline int arp_fwd_proxy(struct in_device *in_dev, struct rtable *rt)
530 struct in_device *out_dev;
533 if (!IN_DEV_PROXY_ARP(in_dev))
536 if ((imi = IN_DEV_MEDIUM_ID(in_dev)) == 0)
541 /* place to check for proxy_arp for routes */
543 if ((out_dev = in_dev_get(rt->u.dst.dev)) != NULL) {
544 omi = IN_DEV_MEDIUM_ID(out_dev);
547 return (omi != imi && omi != -1);
551 * Interface to link layer: send routine and receive handler.
555 * Create an arp packet. If (dest_hw == NULL), we create a broadcast
558 struct sk_buff *arp_create(int type, int ptype, u32 dest_ip,
559 struct net_device *dev, u32 src_ip,
560 unsigned char *dest_hw, unsigned char *src_hw,
561 unsigned char *target_hw)
565 unsigned char *arp_ptr;
571 skb = alloc_skb(sizeof(struct arphdr)+ 2*(dev->addr_len+4)
572 + LL_RESERVED_SPACE(dev), GFP_ATOMIC);
576 skb_reserve(skb, LL_RESERVED_SPACE(dev));
577 skb->nh.raw = skb->data;
578 arp = (struct arphdr *) skb_put(skb,sizeof(struct arphdr) + 2*(dev->addr_len+4));
580 skb->protocol = htons(ETH_P_ARP);
582 src_hw = dev->dev_addr;
584 dest_hw = dev->broadcast;
587 * Fill the device header for the ARP frame
589 if (dev->hard_header &&
590 dev->hard_header(skb,dev,ptype,dest_hw,src_hw,skb->len) < 0)
594 * Fill out the arp protocol part.
596 * The arp hardware type should match the device type, except for FDDI,
597 * which (according to RFC 1390) should always equal 1 (Ethernet).
600 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
601 * DIX code for the protocol. Make these device structure fields.
605 arp->ar_hrd = htons(dev->type);
606 arp->ar_pro = htons(ETH_P_IP);
609 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
611 arp->ar_hrd = htons(ARPHRD_AX25);
612 arp->ar_pro = htons(AX25_P_IP);
615 #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
617 arp->ar_hrd = htons(ARPHRD_NETROM);
618 arp->ar_pro = htons(AX25_P_IP);
625 arp->ar_hrd = htons(ARPHRD_ETHER);
626 arp->ar_pro = htons(ETH_P_IP);
630 case ARPHRD_IEEE802_TR:
631 arp->ar_hrd = htons(ARPHRD_IEEE802);
632 arp->ar_pro = htons(ETH_P_IP);
637 arp->ar_hln = dev->addr_len;
639 arp->ar_op = htons(type);
641 arp_ptr=(unsigned char *)(arp+1);
643 memcpy(arp_ptr, src_hw, dev->addr_len);
644 arp_ptr+=dev->addr_len;
645 memcpy(arp_ptr, &src_ip,4);
647 if (target_hw != NULL)
648 memcpy(arp_ptr, target_hw, dev->addr_len);
650 memset(arp_ptr, 0, dev->addr_len);
651 arp_ptr+=dev->addr_len;
652 memcpy(arp_ptr, &dest_ip, 4);
662 * Send an arp packet.
664 void arp_xmit(struct sk_buff *skb)
666 /* Send it off, maybe filter it using firewalling first. */
667 NF_HOOK(NF_ARP, NF_ARP_OUT, skb, NULL, skb->dev, dev_queue_xmit);
671 * Create and send an arp packet.
673 void arp_send(int type, int ptype, u32 dest_ip,
674 struct net_device *dev, u32 src_ip,
675 unsigned char *dest_hw, unsigned char *src_hw,
676 unsigned char *target_hw)
681 * No arp on this interface.
684 if (dev->flags&IFF_NOARP)
687 skb = arp_create(type, ptype, dest_ip, dev, src_ip,
688 dest_hw, src_hw, target_hw);
696 static void parp_redo(struct sk_buff *skb)
698 arp_rcv(skb, skb->dev, NULL);
702 * Process an arp request.
705 int arp_process(struct sk_buff *skb)
707 struct net_device *dev = skb->dev;
708 struct in_device *in_dev = in_dev_get(dev);
710 unsigned char *arp_ptr;
712 unsigned char *sha, *tha;
714 u16 dev_type = dev->type;
718 /* arp_rcv below verifies the ARP header and verifies the device
729 if (arp->ar_pro != htons(ETH_P_IP) ||
730 htons(dev_type) != arp->ar_hrd)
733 #ifdef CONFIG_NET_ETHERNET
737 case ARPHRD_IEEE802_TR:
745 #if defined(CONFIG_NET_ETHERNET) || defined(CONFIG_TR) || \
746 defined(CONFIG_FDDI) || defined(CONFIG_NET_FC)
748 * ETHERNET, Token Ring and Fibre Channel (which are IEEE 802
749 * devices, according to RFC 2625) devices will accept ARP
750 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
751 * This is the case also of FDDI, where the RFC 1390 says that
752 * FDDI devices should accept ARP hardware of (1) Ethernet,
753 * however, to be more robust, we'll accept both 1 (Ethernet)
756 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
757 arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
758 arp->ar_pro != htons(ETH_P_IP))
762 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
764 if (arp->ar_pro != htons(AX25_P_IP) ||
765 arp->ar_hrd != htons(ARPHRD_AX25))
768 #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
770 if (arp->ar_pro != htons(AX25_P_IP) ||
771 arp->ar_hrd != htons(ARPHRD_NETROM))
778 /* Understand only these message types */
780 if (arp->ar_op != htons(ARPOP_REPLY) &&
781 arp->ar_op != htons(ARPOP_REQUEST))
787 arp_ptr= (unsigned char *)(arp+1);
789 arp_ptr += dev->addr_len;
790 memcpy(&sip, arp_ptr, 4);
793 arp_ptr += dev->addr_len;
794 memcpy(&tip, arp_ptr, 4);
796 * Check for bad requests for 127.x.x.x and requests for multicast
797 * addresses. If this is one such, delete it.
799 if (LOOPBACK(tip) || MULTICAST(tip))
803 * Special case: We must set Frame Relay source Q.922 address
805 if (dev_type == ARPHRD_DLCI)
806 sha = dev->broadcast;
809 * Process entry. The idea here is we want to send a reply if it is a
810 * request for us or if it is a request for someone else that we hold
811 * a proxy for. We want to add an entry to our cache if it is a reply
812 * to us or if it is a request for our address.
813 * (The assumption for this last is that if someone is requesting our
814 * address, they are probably intending to talk to us, so it saves time
815 * if we cache their address. Their address is also probably not in
816 * our cache, since ours is not in their cache.)
818 * Putting this another way, we only care about replies if they are to
819 * us, in which case we add them to the cache. For requests, we care
820 * about those for us and those for our proxies. We reply to both,
821 * and in the case of requests for us we add the requester to the arp
825 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
827 if (arp->ar_op == htons(ARPOP_REQUEST) &&
828 inet_addr_type(tip) == RTN_LOCAL &&
829 !arp_ignore(in_dev,dev,sip,tip))
830 arp_send(ARPOP_REPLY,ETH_P_ARP,tip,dev,tip,sha,dev->dev_addr,dev->dev_addr);
834 if (arp->ar_op == htons(ARPOP_REQUEST) &&
835 ip_route_input(skb, tip, sip, 0, dev) == 0) {
837 rt = (struct rtable*)skb->dst;
838 addr_type = rt->rt_type;
840 if (addr_type == RTN_LOCAL) {
841 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
846 dont_send |= arp_ignore(in_dev,dev,sip,tip);
847 if (!dont_send && IN_DEV_ARPFILTER(in_dev))
848 dont_send |= arp_filter(sip,tip,dev);
850 arp_send(ARPOP_REPLY,ETH_P_ARP,sip,dev,tip,sha,dev->dev_addr,sha);
855 } else if (IN_DEV_FORWARD(in_dev)) {
856 if ((rt->rt_flags&RTCF_DNAT) ||
857 (addr_type == RTN_UNICAST && rt->u.dst.dev != dev &&
858 (arp_fwd_proxy(in_dev, rt) || pneigh_lookup(&arp_tbl, &tip, dev, 0)))) {
859 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
863 if (skb->stamp.tv_sec == LOCALLY_ENQUEUED ||
864 skb->pkt_type == PACKET_HOST ||
865 in_dev->arp_parms->proxy_delay == 0) {
866 arp_send(ARPOP_REPLY,ETH_P_ARP,sip,dev,tip,sha,dev->dev_addr,sha);
868 pneigh_enqueue(&arp_tbl, in_dev->arp_parms, skb);
877 /* Update our ARP tables */
879 n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
881 #ifdef CONFIG_IP_ACCEPT_UNSOLICITED_ARP
882 /* Unsolicited ARP is not accepted by default.
883 It is possible, that this option should be enabled for some
884 devices (strip is candidate)
887 arp->ar_op == htons(ARPOP_REPLY) &&
888 inet_addr_type(sip) == RTN_UNICAST)
889 n = __neigh_lookup(&arp_tbl, &sip, dev, -1);
893 int state = NUD_REACHABLE;
896 /* If several different ARP replies follows back-to-back,
897 use the FIRST one. It is possible, if several proxy
898 agents are active. Taking the first reply prevents
899 arp trashing and chooses the fastest router.
901 override = time_after(jiffies, n->updated + n->parms->locktime);
903 /* Broadcast replies and request packets
904 do not assert neighbour reachability.
906 if (arp->ar_op != htons(ARPOP_REPLY) ||
907 skb->pkt_type != PACKET_HOST)
909 neigh_update(n, sha, state, override, 1);
922 * Receive an arp request from the device layer.
925 int arp_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt)
929 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
930 if (!pskb_may_pull(skb, (sizeof(struct arphdr) +
931 (2 * dev->addr_len) +
936 if (arp->ar_hln != dev->addr_len ||
937 dev->flags & IFF_NOARP ||
938 skb->pkt_type == PACKET_OTHERHOST ||
939 skb->pkt_type == PACKET_LOOPBACK ||
943 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
946 return NF_HOOK(NF_ARP, NF_ARP_IN, skb, dev, NULL, arp_process);
955 * User level interface (ioctl)
959 * Set (create) an ARP cache entry.
962 int arp_req_set(struct arpreq *r, struct net_device * dev)
964 u32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
965 struct neighbour *neigh;
968 if (r->arp_flags&ATF_PUBL) {
969 u32 mask = ((struct sockaddr_in *) &r->arp_netmask)->sin_addr.s_addr;
970 if (mask && mask != 0xFFFFFFFF)
972 if (!dev && (r->arp_flags & ATF_COM)) {
973 dev = dev_getbyhwaddr(r->arp_ha.sa_family, r->arp_ha.sa_data);
978 if (pneigh_lookup(&arp_tbl, &ip, dev, 1) == NULL)
983 ipv4_devconf.proxy_arp = 1;
986 if (__in_dev_get(dev)) {
987 __in_dev_get(dev)->cnf.proxy_arp = 1;
993 if (r->arp_flags & ATF_PERM)
994 r->arp_flags |= ATF_COM;
996 struct flowi fl = { .nl_u = { .ip4_u = { .daddr = ip,
997 .tos = RTO_ONLINK } } };
999 if ((err = ip_route_output_key(&rt, &fl)) != 0)
1001 dev = rt->u.dst.dev;
1006 if (r->arp_ha.sa_family != dev->type)
1009 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1010 err = PTR_ERR(neigh);
1011 if (!IS_ERR(neigh)) {
1012 unsigned state = NUD_STALE;
1013 if (r->arp_flags & ATF_PERM)
1014 state = NUD_PERMANENT;
1015 err = neigh_update(neigh, (r->arp_flags&ATF_COM) ?
1016 r->arp_ha.sa_data : NULL, state, 1, 0);
1017 neigh_release(neigh);
1022 static unsigned arp_state_to_flags(struct neighbour *neigh)
1025 if (neigh->nud_state&NUD_PERMANENT)
1026 flags = ATF_PERM|ATF_COM;
1027 else if (neigh->nud_state&NUD_VALID)
1033 * Get an ARP cache entry.
1036 static int arp_req_get(struct arpreq *r, struct net_device *dev)
1038 u32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1039 struct neighbour *neigh;
1042 neigh = neigh_lookup(&arp_tbl, &ip, dev);
1044 read_lock_bh(&neigh->lock);
1045 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
1046 r->arp_flags = arp_state_to_flags(neigh);
1047 read_unlock_bh(&neigh->lock);
1048 r->arp_ha.sa_family = dev->type;
1049 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1050 neigh_release(neigh);
1056 int arp_req_delete(struct arpreq *r, struct net_device * dev)
1059 u32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1060 struct neighbour *neigh;
1062 if (r->arp_flags & ATF_PUBL) {
1064 ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1065 if (mask == 0xFFFFFFFF)
1066 return pneigh_delete(&arp_tbl, &ip, dev);
1069 ipv4_devconf.proxy_arp = 0;
1072 if (__in_dev_get(dev)) {
1073 __in_dev_get(dev)->cnf.proxy_arp = 0;
1082 struct flowi fl = { .nl_u = { .ip4_u = { .daddr = ip,
1083 .tos = RTO_ONLINK } } };
1085 if ((err = ip_route_output_key(&rt, &fl)) != 0)
1087 dev = rt->u.dst.dev;
1093 neigh = neigh_lookup(&arp_tbl, &ip, dev);
1095 if (neigh->nud_state&~NUD_NOARP)
1096 err = neigh_update(neigh, NULL, NUD_FAILED, 1, 0);
1097 neigh_release(neigh);
1103 * Handle an ARP layer I/O control request.
1106 int arp_ioctl(unsigned int cmd, void __user *arg)
1110 struct net_device *dev = NULL;
1115 if (!capable(CAP_NET_ADMIN))
1118 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1126 if (r.arp_pa.sa_family != AF_INET)
1127 return -EPFNOSUPPORT;
1129 if (!(r.arp_flags & ATF_PUBL) &&
1130 (r.arp_flags & (ATF_NETMASK|ATF_DONTPUB)))
1132 if (!(r.arp_flags & ATF_NETMASK))
1133 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1134 htonl(0xFFFFFFFFUL);
1138 if ((dev = __dev_get_by_name(r.arp_dev)) == NULL)
1141 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1142 if (!r.arp_ha.sa_family)
1143 r.arp_ha.sa_family = dev->type;
1145 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1147 } else if (cmd == SIOCGARP) {
1154 err = arp_req_delete(&r, dev);
1157 err = arp_req_set(&r, dev);
1160 err = arp_req_get(&r, dev);
1161 if (!err && copy_to_user(arg, &r, sizeof(r)))
1170 static int arp_netdev_event(struct notifier_block *this, unsigned long event, void *ptr)
1172 struct net_device *dev = ptr;
1175 case NETDEV_CHANGEADDR:
1176 neigh_changeaddr(&arp_tbl, dev);
1186 struct notifier_block arp_netdev_notifier = {
1187 .notifier_call = arp_netdev_event,
1190 /* Note, that it is not on notifier chain.
1191 It is necessary, that this routine was called after route cache will be
1194 void arp_ifdown(struct net_device *dev)
1196 neigh_ifdown(&arp_tbl, dev);
1201 * Called once on startup.
1204 static struct packet_type arp_packet_type = {
1205 .type = __constant_htons(ETH_P_ARP),
1209 static int arp_proc_init(void);
1211 void __init arp_init(void)
1213 neigh_table_init(&arp_tbl);
1215 dev_add_pack(&arp_packet_type);
1217 #ifdef CONFIG_SYSCTL
1218 neigh_sysctl_register(NULL, &arp_tbl.parms, NET_IPV4,
1219 NET_IPV4_NEIGH, "ipv4", NULL);
1221 register_netdevice_notifier(&arp_netdev_notifier);
1224 #ifdef CONFIG_PROC_FS
1225 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1227 /* ------------------------------------------------------------------------ */
1229 * ax25 -> ASCII conversion
1231 static char *ax2asc2(ax25_address *a, char *buf)
1236 for (n = 0, s = buf; n < 6; n++) {
1237 c = (a->ax25_call[n] >> 1) & 0x7F;
1239 if (c != ' ') *s++ = c;
1244 if ((n = ((a->ax25_call[6] >> 1) & 0x0F)) > 9) {
1252 if (*buf == '\0' || *buf == '-')
1258 #endif /* CONFIG_AX25 */
1260 struct arp_iter_state {
1261 int is_pneigh, bucket;
1264 static struct neighbour *neigh_get_first(struct seq_file *seq)
1266 struct arp_iter_state* state = seq->private;
1267 struct neighbour *n = NULL;
1269 state->is_pneigh = 0;
1271 for (state->bucket = 0;
1272 state->bucket <= NEIGH_HASHMASK;
1274 n = arp_tbl.hash_buckets[state->bucket];
1275 while (n && !(n->nud_state & ~NUD_NOARP))
1284 static struct neighbour *neigh_get_next(struct seq_file *seq,
1285 struct neighbour *n)
1287 struct arp_iter_state* state = seq->private;
1291 /* Don't confuse "arp -a" w/ magic entries */
1294 } while (n && !(n->nud_state & ~NUD_NOARP));
1298 if (++state->bucket > NEIGH_HASHMASK)
1300 n = arp_tbl.hash_buckets[state->bucket];
1306 static struct neighbour *neigh_get_idx(struct seq_file *seq, loff_t *pos)
1308 struct neighbour *n = neigh_get_first(seq);
1311 while (*pos && (n = neigh_get_next(seq, n)))
1313 return *pos ? NULL : n;
1316 static struct pneigh_entry *pneigh_get_first(struct seq_file *seq)
1318 struct arp_iter_state* state = seq->private;
1319 struct pneigh_entry *pn;
1321 state->is_pneigh = 1;
1323 for (state->bucket = 0;
1324 state->bucket <= PNEIGH_HASHMASK;
1326 pn = arp_tbl.phash_buckets[state->bucket];
1333 static struct pneigh_entry *pneigh_get_next(struct seq_file *seq,
1334 struct pneigh_entry *pn)
1336 struct arp_iter_state* state = seq->private;
1340 if (++state->bucket > PNEIGH_HASHMASK)
1342 pn = arp_tbl.phash_buckets[state->bucket];
1347 static struct pneigh_entry *pneigh_get_idx(struct seq_file *seq, loff_t pos)
1349 struct pneigh_entry *pn = pneigh_get_first(seq);
1352 while (pos && (pn = pneigh_get_next(seq, pn)))
1354 return pos ? NULL : pn;
1357 static void *arp_get_idx(struct seq_file *seq, loff_t pos)
1361 read_lock_bh(&arp_tbl.lock);
1362 rc = neigh_get_idx(seq, &pos);
1365 read_unlock_bh(&arp_tbl.lock);
1366 rc = pneigh_get_idx(seq, pos);
1371 static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1373 struct arp_iter_state* state = seq->private;
1375 state->is_pneigh = 0;
1377 return *pos ? arp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
1380 static void *arp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1383 struct arp_iter_state* state;
1385 if (v == SEQ_START_TOKEN) {
1386 rc = arp_get_idx(seq, 0);
1390 state = seq->private;
1391 if (!state->is_pneigh) {
1392 rc = neigh_get_next(seq, v);
1395 read_unlock_bh(&arp_tbl.lock);
1396 rc = pneigh_get_first(seq);
1398 rc = pneigh_get_next(seq, v);
1404 static void arp_seq_stop(struct seq_file *seq, void *v)
1406 struct arp_iter_state* state = seq->private;
1408 if (!state->is_pneigh && v != SEQ_START_TOKEN)
1409 read_unlock_bh(&arp_tbl.lock);
1412 #define HBUFFERLEN 30
1414 static __inline__ void arp_format_neigh_entry(struct seq_file *seq,
1415 struct neighbour *n)
1417 char hbuffer[HBUFFERLEN];
1418 const char hexbuf[] = "0123456789ABCDEF";
1421 struct net_device *dev = n->dev;
1422 int hatype = dev->type;
1424 read_lock(&n->lock);
1425 /* Convert hardware address to XX:XX:XX:XX ... form. */
1426 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1427 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1428 ax2asc2((ax25_address *)n->ha, hbuffer);
1431 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1432 hbuffer[k++] = hexbuf[(n->ha[j] >> 4) & 15];
1433 hbuffer[k++] = hexbuf[n->ha[j] & 15];
1437 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1440 sprintf(tbuf, "%u.%u.%u.%u", NIPQUAD(*(u32*)n->primary_key));
1441 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1442 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1443 read_unlock(&n->lock);
1446 static __inline__ void arp_format_pneigh_entry(struct seq_file *seq,
1447 struct pneigh_entry *n)
1449 struct net_device *dev = n->dev;
1450 int hatype = dev ? dev->type : 0;
1453 sprintf(tbuf, "%u.%u.%u.%u", NIPQUAD(*(u32*)n->key));
1454 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1455 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1456 dev ? dev->name : "*");
1459 static int arp_seq_show(struct seq_file *seq, void *v)
1461 if (v == SEQ_START_TOKEN)
1462 seq_puts(seq, "IP address HW type Flags "
1463 "HW address Mask Device\n");
1465 struct arp_iter_state* state = seq->private;
1467 if (state->is_pneigh)
1468 arp_format_pneigh_entry(seq, v);
1470 arp_format_neigh_entry(seq, v);
1476 /* ------------------------------------------------------------------------ */
1478 static struct seq_operations arp_seq_ops = {
1479 .start = arp_seq_start,
1480 .next = arp_seq_next,
1481 .stop = arp_seq_stop,
1482 .show = arp_seq_show,
1485 static int arp_seq_open(struct inode *inode, struct file *file)
1487 struct seq_file *seq;
1489 struct arp_iter_state *s = kmalloc(sizeof(*s), GFP_KERNEL);
1494 rc = seq_open(file, &arp_seq_ops);
1498 seq = file->private_data;
1507 static struct file_operations arp_seq_fops = {
1508 .owner = THIS_MODULE,
1509 .open = arp_seq_open,
1511 .llseek = seq_lseek,
1512 .release = seq_release_private,
1515 static int __init arp_proc_init(void)
1517 if (!proc_net_fops_create("arp", S_IRUGO, &arp_seq_fops))
1522 #else /* CONFIG_PROC_FS */
1524 static int __init arp_proc_init(void)
1529 #endif /* CONFIG_PROC_FS */
1531 EXPORT_SYMBOL(arp_broken_ops);
1532 EXPORT_SYMBOL(arp_find);
1533 EXPORT_SYMBOL(arp_rcv);
1534 EXPORT_SYMBOL(arp_create);
1535 EXPORT_SYMBOL(arp_xmit);
1536 EXPORT_SYMBOL(arp_send);
1537 EXPORT_SYMBOL(arp_tbl);
1539 #if defined(CONFIG_ATM_CLIP) || defined(CONFIG_ATM_CLIP_MODULE)
1540 EXPORT_SYMBOL(clip_tbl_hook);