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>
116 #include <linux/uaccess.h>
118 #include <linux/netfilter_arp.h>
121 * Interface to generic neighbour cache.
123 static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd);
124 static int arp_constructor(struct neighbour *neigh);
125 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
126 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
127 static void parp_redo(struct sk_buff *skb);
129 static const struct neigh_ops arp_generic_ops = {
131 .solicit = arp_solicit,
132 .error_report = arp_error_report,
133 .output = neigh_resolve_output,
134 .connected_output = neigh_connected_output,
137 static const struct neigh_ops arp_hh_ops = {
139 .solicit = arp_solicit,
140 .error_report = arp_error_report,
141 .output = neigh_resolve_output,
142 .connected_output = neigh_resolve_output,
145 static const struct neigh_ops arp_direct_ops = {
147 .output = neigh_direct_output,
148 .connected_output = neigh_direct_output,
151 static const struct neigh_ops arp_broken_ops = {
153 .solicit = arp_solicit,
154 .error_report = arp_error_report,
155 .output = neigh_compat_output,
156 .connected_output = neigh_compat_output,
159 struct neigh_table arp_tbl = {
163 .constructor = arp_constructor,
164 .proxy_redo = parp_redo,
168 .base_reachable_time = 30 * HZ,
169 .retrans_time = 1 * HZ,
170 .gc_staletime = 60 * HZ,
171 .reachable_time = 30 * HZ,
172 .delay_probe_time = 5 * HZ,
173 .queue_len_bytes = 64*1024,
176 .anycast_delay = 1 * HZ,
177 .proxy_delay = (8 * HZ) / 10,
181 .gc_interval = 30 * HZ,
186 EXPORT_SYMBOL(arp_tbl);
188 int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir)
194 ip_eth_mc_map(addr, haddr);
196 case ARPHRD_IEEE802_TR:
197 ip_tr_mc_map(addr, haddr);
199 case ARPHRD_INFINIBAND:
200 ip_ib_mc_map(addr, dev->broadcast, haddr);
203 ip_ipgre_mc_map(addr, dev->broadcast, haddr);
207 memcpy(haddr, dev->broadcast, dev->addr_len);
215 static u32 arp_hash(const void *pkey,
216 const struct net_device *dev,
219 return arp_hashfn(*(u32 *)pkey, dev, *hash_rnd);
222 static int arp_constructor(struct neighbour *neigh)
224 __be32 addr = *(__be32 *)neigh->primary_key;
225 struct net_device *dev = neigh->dev;
226 struct in_device *in_dev;
227 struct neigh_parms *parms;
230 in_dev = __in_dev_get_rcu(dev);
231 if (in_dev == NULL) {
236 neigh->type = inet_addr_type(dev_net(dev), addr);
238 parms = in_dev->arp_parms;
239 __neigh_parms_put(neigh->parms);
240 neigh->parms = neigh_parms_clone(parms);
243 if (!dev->header_ops) {
244 neigh->nud_state = NUD_NOARP;
245 neigh->ops = &arp_direct_ops;
246 neigh->output = neigh_direct_output;
248 /* Good devices (checked by reading texts, but only Ethernet is
251 ARPHRD_ETHER: (ethernet, apfddi)
254 ARPHRD_METRICOM: (strip)
258 ARPHRD_IPDDP will also work, if author repairs it.
259 I did not it, because this driver does not work even
264 /* So... these "amateur" devices are hopeless.
265 The only thing, that I can say now:
266 It is very sad that we need to keep ugly obsolete
267 code to make them happy.
269 They should be moved to more reasonable state, now
270 they use rebuild_header INSTEAD OF hard_start_xmit!!!
271 Besides that, they are sort of out of date
272 (a lot of redundant clones/copies, useless in 2.1),
273 I wonder why people believe that they work.
279 #if IS_ENABLED(CONFIG_AX25)
281 #if IS_ENABLED(CONFIG_NETROM)
284 neigh->ops = &arp_broken_ops;
285 neigh->output = neigh->ops->output;
292 if (neigh->type == RTN_MULTICAST) {
293 neigh->nud_state = NUD_NOARP;
294 arp_mc_map(addr, neigh->ha, dev, 1);
295 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) {
296 neigh->nud_state = NUD_NOARP;
297 memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
298 } else if (neigh->type == RTN_BROADCAST ||
299 (dev->flags & IFF_POINTOPOINT)) {
300 neigh->nud_state = NUD_NOARP;
301 memcpy(neigh->ha, dev->broadcast, dev->addr_len);
304 if (dev->header_ops->cache)
305 neigh->ops = &arp_hh_ops;
307 neigh->ops = &arp_generic_ops;
309 if (neigh->nud_state & NUD_VALID)
310 neigh->output = neigh->ops->connected_output;
312 neigh->output = neigh->ops->output;
317 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
319 dst_link_failure(skb);
323 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
327 struct net_device *dev = neigh->dev;
328 __be32 target = *(__be32 *)neigh->primary_key;
329 int probes = atomic_read(&neigh->probes);
330 struct in_device *in_dev;
333 in_dev = __in_dev_get_rcu(dev);
338 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
340 case 0: /* By default announce any local IP */
341 if (skb && inet_addr_type(dev_net(dev),
342 ip_hdr(skb)->saddr) == RTN_LOCAL)
343 saddr = ip_hdr(skb)->saddr;
345 case 1: /* Restrict announcements of saddr in same subnet */
348 saddr = ip_hdr(skb)->saddr;
349 if (inet_addr_type(dev_net(dev), saddr) == RTN_LOCAL) {
350 /* saddr should be known to target */
351 if (inet_addr_onlink(in_dev, target, saddr))
356 case 2: /* Avoid secondary IPs, get a primary/preferred one */
362 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
364 probes -= neigh->parms->ucast_probes;
366 if (!(neigh->nud_state & NUD_VALID))
368 "trying to ucast probe in NUD_INVALID\n");
370 read_lock_bh(&neigh->lock);
372 probes -= neigh->parms->app_probes;
381 arp_send(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
382 dst_ha, dev->dev_addr, NULL);
384 read_unlock_bh(&neigh->lock);
387 static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip)
391 switch (IN_DEV_ARP_IGNORE(in_dev)) {
392 case 0: /* Reply, the tip is already validated */
394 case 1: /* Reply only if tip is configured on the incoming interface */
396 scope = RT_SCOPE_HOST;
399 * Reply only if tip is configured on the incoming interface
400 * and is in same subnet as sip
402 scope = RT_SCOPE_HOST;
404 case 3: /* Do not reply for scope host addresses */
406 scope = RT_SCOPE_LINK;
408 case 4: /* Reserved */
413 case 8: /* Do not reply */
418 return !inet_confirm_addr(in_dev, sip, tip, scope);
421 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
425 /*unsigned long now; */
426 struct net *net = dev_net(dev);
428 rt = ip_route_output(net, sip, tip, 0, 0);
431 if (rt->dst.dev != dev) {
432 NET_INC_STATS_BH(net, LINUX_MIB_ARPFILTER);
439 /* OBSOLETE FUNCTIONS */
442 * Find an arp mapping in the cache. If not found, post a request.
444 * It is very UGLY routine: it DOES NOT use skb->dst->neighbour,
445 * even if it exists. It is supposed that skb->dev was mangled
446 * by a virtual device (eql, shaper). Nobody but broken devices
447 * is allowed to use this function, it is scheduled to be removed. --ANK
450 static int arp_set_predefined(int addr_hint, unsigned char *haddr,
451 __be32 paddr, struct net_device *dev)
455 printk(KERN_DEBUG "ARP: arp called for own IP address\n");
456 memcpy(haddr, dev->dev_addr, dev->addr_len);
459 arp_mc_map(paddr, haddr, dev, 1);
462 memcpy(haddr, dev->broadcast, dev->addr_len);
469 int arp_find(unsigned char *haddr, struct sk_buff *skb)
471 struct net_device *dev = skb->dev;
476 printk(KERN_DEBUG "arp_find is called with dst==NULL\n");
481 paddr = skb_rtable(skb)->rt_gateway;
483 if (arp_set_predefined(inet_addr_type(dev_net(dev), paddr), haddr,
487 n = __neigh_lookup(&arp_tbl, &paddr, dev, 1);
491 if (n->nud_state & NUD_VALID || neigh_event_send(n, skb) == 0) {
492 neigh_ha_snapshot(haddr, n, dev);
501 EXPORT_SYMBOL(arp_find);
503 /* END OF OBSOLETE FUNCTIONS */
506 * Check if we can use proxy ARP for this path
508 static inline int arp_fwd_proxy(struct in_device *in_dev,
509 struct net_device *dev, struct rtable *rt)
511 struct in_device *out_dev;
514 if (rt->dst.dev == dev)
517 if (!IN_DEV_PROXY_ARP(in_dev))
519 imi = IN_DEV_MEDIUM_ID(in_dev);
525 /* place to check for proxy_arp for routes */
527 out_dev = __in_dev_get_rcu(rt->dst.dev);
529 omi = IN_DEV_MEDIUM_ID(out_dev);
531 return omi != imi && omi != -1;
535 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
537 * RFC3069 supports proxy arp replies back to the same interface. This
538 * is done to support (ethernet) switch features, like RFC 3069, where
539 * the individual ports are not allowed to communicate with each
540 * other, BUT they are allowed to talk to the upstream router. As
541 * described in RFC 3069, it is possible to allow these hosts to
542 * communicate through the upstream router, by proxy_arp'ing.
544 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
546 * This technology is known by different names:
547 * In RFC 3069 it is called VLAN Aggregation.
548 * Cisco and Allied Telesyn call it Private VLAN.
549 * Hewlett-Packard call it Source-Port filtering or port-isolation.
550 * Ericsson call it MAC-Forced Forwarding (RFC Draft).
553 static inline int arp_fwd_pvlan(struct in_device *in_dev,
554 struct net_device *dev, struct rtable *rt,
555 __be32 sip, __be32 tip)
557 /* Private VLAN is only concerned about the same ethernet segment */
558 if (rt->dst.dev != dev)
561 /* Don't reply on self probes (often done by windowz boxes)*/
565 if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
572 * Interface to link layer: send routine and receive handler.
576 * Create an arp packet. If (dest_hw == NULL), we create a broadcast
579 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
580 struct net_device *dev, __be32 src_ip,
581 const unsigned char *dest_hw,
582 const unsigned char *src_hw,
583 const unsigned char *target_hw)
587 unsigned char *arp_ptr;
588 int hlen = LL_RESERVED_SPACE(dev);
589 int tlen = dev->needed_tailroom;
595 skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
599 skb_reserve(skb, hlen);
600 skb_reset_network_header(skb);
601 arp = (struct arphdr *) skb_put(skb, arp_hdr_len(dev));
603 skb->protocol = htons(ETH_P_ARP);
605 src_hw = dev->dev_addr;
607 dest_hw = dev->broadcast;
610 * Fill the device header for the ARP frame
612 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
616 * Fill out the arp protocol part.
618 * The arp hardware type should match the device type, except for FDDI,
619 * which (according to RFC 1390) should always equal 1 (Ethernet).
622 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
623 * DIX code for the protocol. Make these device structure fields.
627 arp->ar_hrd = htons(dev->type);
628 arp->ar_pro = htons(ETH_P_IP);
631 #if IS_ENABLED(CONFIG_AX25)
633 arp->ar_hrd = htons(ARPHRD_AX25);
634 arp->ar_pro = htons(AX25_P_IP);
637 #if IS_ENABLED(CONFIG_NETROM)
639 arp->ar_hrd = htons(ARPHRD_NETROM);
640 arp->ar_pro = htons(AX25_P_IP);
645 #if IS_ENABLED(CONFIG_FDDI)
647 arp->ar_hrd = htons(ARPHRD_ETHER);
648 arp->ar_pro = htons(ETH_P_IP);
651 #if IS_ENABLED(CONFIG_TR)
652 case ARPHRD_IEEE802_TR:
653 arp->ar_hrd = htons(ARPHRD_IEEE802);
654 arp->ar_pro = htons(ETH_P_IP);
659 arp->ar_hln = dev->addr_len;
661 arp->ar_op = htons(type);
663 arp_ptr = (unsigned char *)(arp + 1);
665 memcpy(arp_ptr, src_hw, dev->addr_len);
666 arp_ptr += dev->addr_len;
667 memcpy(arp_ptr, &src_ip, 4);
669 if (target_hw != NULL)
670 memcpy(arp_ptr, target_hw, dev->addr_len);
672 memset(arp_ptr, 0, dev->addr_len);
673 arp_ptr += dev->addr_len;
674 memcpy(arp_ptr, &dest_ip, 4);
682 EXPORT_SYMBOL(arp_create);
685 * Send an arp packet.
687 void arp_xmit(struct sk_buff *skb)
689 /* Send it off, maybe filter it using firewalling first. */
690 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, skb, NULL, skb->dev, dev_queue_xmit);
692 EXPORT_SYMBOL(arp_xmit);
695 * Create and send an arp packet.
697 void arp_send(int type, int ptype, __be32 dest_ip,
698 struct net_device *dev, __be32 src_ip,
699 const unsigned char *dest_hw, const unsigned char *src_hw,
700 const unsigned char *target_hw)
705 * No arp on this interface.
708 if (dev->flags&IFF_NOARP)
711 skb = arp_create(type, ptype, dest_ip, dev, src_ip,
712 dest_hw, src_hw, target_hw);
718 EXPORT_SYMBOL(arp_send);
721 * Process an arp request.
724 static int arp_process(struct sk_buff *skb)
726 struct net_device *dev = skb->dev;
727 struct in_device *in_dev = __in_dev_get_rcu(dev);
729 unsigned char *arp_ptr;
733 u16 dev_type = dev->type;
736 struct net *net = dev_net(dev);
738 /* arp_rcv below verifies the ARP header and verifies the device
749 if (arp->ar_pro != htons(ETH_P_IP) ||
750 htons(dev_type) != arp->ar_hrd)
754 case ARPHRD_IEEE802_TR:
758 * ETHERNET, Token Ring and Fibre Channel (which are IEEE 802
759 * devices, according to RFC 2625) devices will accept ARP
760 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
761 * This is the case also of FDDI, where the RFC 1390 says that
762 * FDDI devices should accept ARP hardware of (1) Ethernet,
763 * however, to be more robust, we'll accept both 1 (Ethernet)
766 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
767 arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
768 arp->ar_pro != htons(ETH_P_IP))
772 if (arp->ar_pro != htons(AX25_P_IP) ||
773 arp->ar_hrd != htons(ARPHRD_AX25))
777 if (arp->ar_pro != htons(AX25_P_IP) ||
778 arp->ar_hrd != htons(ARPHRD_NETROM))
783 /* Understand only these message types */
785 if (arp->ar_op != htons(ARPOP_REPLY) &&
786 arp->ar_op != htons(ARPOP_REQUEST))
792 arp_ptr = (unsigned char *)(arp + 1);
794 arp_ptr += dev->addr_len;
795 memcpy(&sip, arp_ptr, 4);
797 arp_ptr += dev->addr_len;
798 memcpy(&tip, arp_ptr, 4);
800 * Check for bad requests for 127.x.x.x and requests for multicast
801 * addresses. If this is one such, delete it.
803 if (ipv4_is_loopback(tip) || ipv4_is_multicast(tip))
807 * Special case: We must set Frame Relay source Q.922 address
809 if (dev_type == ARPHRD_DLCI)
810 sha = dev->broadcast;
813 * Process entry. The idea here is we want to send a reply if it is a
814 * request for us or if it is a request for someone else that we hold
815 * a proxy for. We want to add an entry to our cache if it is a reply
816 * to us or if it is a request for our address.
817 * (The assumption for this last is that if someone is requesting our
818 * address, they are probably intending to talk to us, so it saves time
819 * if we cache their address. Their address is also probably not in
820 * our cache, since ours is not in their cache.)
822 * Putting this another way, we only care about replies if they are to
823 * us, in which case we add them to the cache. For requests, we care
824 * about those for us and those for our proxies. We reply to both,
825 * and in the case of requests for us we add the requester to the arp
829 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
831 if (arp->ar_op == htons(ARPOP_REQUEST) &&
832 inet_addr_type(net, tip) == RTN_LOCAL &&
833 !arp_ignore(in_dev, sip, tip))
834 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, sha,
839 if (arp->ar_op == htons(ARPOP_REQUEST) &&
840 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
842 rt = skb_rtable(skb);
843 addr_type = rt->rt_type;
845 if (addr_type == RTN_LOCAL) {
848 dont_send = arp_ignore(in_dev, sip, tip);
849 if (!dont_send && IN_DEV_ARPFILTER(in_dev))
850 dont_send = arp_filter(sip, tip, dev);
852 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
854 arp_send(ARPOP_REPLY, ETH_P_ARP, sip,
855 dev, tip, sha, dev->dev_addr,
861 } else if (IN_DEV_FORWARD(in_dev)) {
862 if (addr_type == RTN_UNICAST &&
863 (arp_fwd_proxy(in_dev, dev, rt) ||
864 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
865 (rt->dst.dev != dev &&
866 pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
867 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
871 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
872 skb->pkt_type == PACKET_HOST ||
873 in_dev->arp_parms->proxy_delay == 0) {
874 arp_send(ARPOP_REPLY, ETH_P_ARP, sip,
875 dev, tip, sha, dev->dev_addr,
878 pneigh_enqueue(&arp_tbl,
879 in_dev->arp_parms, skb);
887 /* Update our ARP tables */
889 n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
891 if (IN_DEV_ARP_ACCEPT(in_dev)) {
892 /* Unsolicited ARP is not accepted by default.
893 It is possible, that this option should be enabled for some
894 devices (strip is candidate)
897 (arp->ar_op == htons(ARPOP_REPLY) ||
898 (arp->ar_op == htons(ARPOP_REQUEST) && tip == sip)) &&
899 inet_addr_type(net, sip) == RTN_UNICAST)
900 n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
904 int state = NUD_REACHABLE;
907 /* If several different ARP replies follows back-to-back,
908 use the FIRST one. It is possible, if several proxy
909 agents are active. Taking the first reply prevents
910 arp trashing and chooses the fastest router.
912 override = time_after(jiffies, n->updated + n->parms->locktime);
914 /* Broadcast replies and request packets
915 do not assert neighbour reachability.
917 if (arp->ar_op != htons(ARPOP_REPLY) ||
918 skb->pkt_type != PACKET_HOST)
920 neigh_update(n, sha, state,
921 override ? NEIGH_UPDATE_F_OVERRIDE : 0);
930 static void parp_redo(struct sk_buff *skb)
937 * Receive an arp request from the device layer.
940 static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
941 struct packet_type *pt, struct net_device *orig_dev)
945 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
946 if (!pskb_may_pull(skb, arp_hdr_len(dev)))
950 if (arp->ar_hln != dev->addr_len ||
951 dev->flags & IFF_NOARP ||
952 skb->pkt_type == PACKET_OTHERHOST ||
953 skb->pkt_type == PACKET_LOOPBACK ||
957 skb = skb_share_check(skb, GFP_ATOMIC);
961 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
963 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, skb, dev, NULL, arp_process);
972 * User level interface (ioctl)
976 * Set (create) an ARP cache entry.
979 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
982 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
985 if (__in_dev_get_rtnl(dev)) {
986 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
992 static int arp_req_set_public(struct net *net, struct arpreq *r,
993 struct net_device *dev)
995 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
996 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
998 if (mask && mask != htonl(0xFFFFFFFF))
1000 if (!dev && (r->arp_flags & ATF_COM)) {
1001 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family,
1007 if (pneigh_lookup(&arp_tbl, net, &ip, dev, 1) == NULL)
1012 return arp_req_set_proxy(net, dev, 1);
1015 static int arp_req_set(struct net *net, struct arpreq *r,
1016 struct net_device *dev)
1019 struct neighbour *neigh;
1022 if (r->arp_flags & ATF_PUBL)
1023 return arp_req_set_public(net, r, dev);
1025 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1026 if (r->arp_flags & ATF_PERM)
1027 r->arp_flags |= ATF_COM;
1029 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1038 switch (dev->type) {
1039 #if IS_ENABLED(CONFIG_FDDI)
1042 * According to RFC 1390, FDDI devices should accept ARP
1043 * hardware types of 1 (Ethernet). However, to be more
1044 * robust, we'll accept hardware types of either 1 (Ethernet)
1045 * or 6 (IEEE 802.2).
1047 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1048 r->arp_ha.sa_family != ARPHRD_ETHER &&
1049 r->arp_ha.sa_family != ARPHRD_IEEE802)
1054 if (r->arp_ha.sa_family != dev->type)
1059 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1060 err = PTR_ERR(neigh);
1061 if (!IS_ERR(neigh)) {
1062 unsigned int state = NUD_STALE;
1063 if (r->arp_flags & ATF_PERM)
1064 state = NUD_PERMANENT;
1065 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ?
1066 r->arp_ha.sa_data : NULL, state,
1067 NEIGH_UPDATE_F_OVERRIDE |
1068 NEIGH_UPDATE_F_ADMIN);
1069 neigh_release(neigh);
1074 static unsigned int arp_state_to_flags(struct neighbour *neigh)
1076 if (neigh->nud_state&NUD_PERMANENT)
1077 return ATF_PERM | ATF_COM;
1078 else if (neigh->nud_state&NUD_VALID)
1085 * Get an ARP cache entry.
1088 static int arp_req_get(struct arpreq *r, struct net_device *dev)
1090 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1091 struct neighbour *neigh;
1094 neigh = neigh_lookup(&arp_tbl, &ip, dev);
1096 read_lock_bh(&neigh->lock);
1097 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
1098 r->arp_flags = arp_state_to_flags(neigh);
1099 read_unlock_bh(&neigh->lock);
1100 r->arp_ha.sa_family = dev->type;
1101 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1102 neigh_release(neigh);
1108 int arp_invalidate(struct net_device *dev, __be32 ip)
1110 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
1114 if (neigh->nud_state & ~NUD_NOARP)
1115 err = neigh_update(neigh, NULL, NUD_FAILED,
1116 NEIGH_UPDATE_F_OVERRIDE|
1117 NEIGH_UPDATE_F_ADMIN);
1118 neigh_release(neigh);
1123 EXPORT_SYMBOL(arp_invalidate);
1125 static int arp_req_delete_public(struct net *net, struct arpreq *r,
1126 struct net_device *dev)
1128 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1129 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1131 if (mask == htonl(0xFFFFFFFF))
1132 return pneigh_delete(&arp_tbl, net, &ip, dev);
1137 return arp_req_set_proxy(net, dev, 0);
1140 static int arp_req_delete(struct net *net, struct arpreq *r,
1141 struct net_device *dev)
1145 if (r->arp_flags & ATF_PUBL)
1146 return arp_req_delete_public(net, r, dev);
1148 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1150 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1158 return arp_invalidate(dev, ip);
1162 * Handle an ARP layer I/O control request.
1165 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1169 struct net_device *dev = NULL;
1174 if (!capable(CAP_NET_ADMIN))
1177 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1185 if (r.arp_pa.sa_family != AF_INET)
1186 return -EPFNOSUPPORT;
1188 if (!(r.arp_flags & ATF_PUBL) &&
1189 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1191 if (!(r.arp_flags & ATF_NETMASK))
1192 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1193 htonl(0xFFFFFFFFUL);
1197 dev = __dev_get_by_name(net, r.arp_dev);
1201 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1202 if (!r.arp_ha.sa_family)
1203 r.arp_ha.sa_family = dev->type;
1205 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1207 } else if (cmd == SIOCGARP) {
1214 err = arp_req_delete(net, &r, dev);
1217 err = arp_req_set(net, &r, dev);
1220 err = arp_req_get(&r, dev);
1225 if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
1230 static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1233 struct net_device *dev = ptr;
1236 case NETDEV_CHANGEADDR:
1237 neigh_changeaddr(&arp_tbl, dev);
1238 rt_cache_flush(dev_net(dev), 0);
1247 static struct notifier_block arp_netdev_notifier = {
1248 .notifier_call = arp_netdev_event,
1251 /* Note, that it is not on notifier chain.
1252 It is necessary, that this routine was called after route cache will be
1255 void arp_ifdown(struct net_device *dev)
1257 neigh_ifdown(&arp_tbl, dev);
1262 * Called once on startup.
1265 static struct packet_type arp_packet_type __read_mostly = {
1266 .type = cpu_to_be16(ETH_P_ARP),
1270 static int arp_proc_init(void);
1272 void __init arp_init(void)
1274 neigh_table_init(&arp_tbl);
1276 dev_add_pack(&arp_packet_type);
1278 #ifdef CONFIG_SYSCTL
1279 neigh_sysctl_register(NULL, &arp_tbl.parms, "ipv4", NULL);
1281 register_netdevice_notifier(&arp_netdev_notifier);
1284 #ifdef CONFIG_PROC_FS
1285 #if IS_ENABLED(CONFIG_AX25)
1287 /* ------------------------------------------------------------------------ */
1289 * ax25 -> ASCII conversion
1291 static char *ax2asc2(ax25_address *a, char *buf)
1296 for (n = 0, s = buf; n < 6; n++) {
1297 c = (a->ax25_call[n] >> 1) & 0x7F;
1304 n = (a->ax25_call[6] >> 1) & 0x0F;
1313 if (*buf == '\0' || *buf == '-')
1318 #endif /* CONFIG_AX25 */
1320 #define HBUFFERLEN 30
1322 static void arp_format_neigh_entry(struct seq_file *seq,
1323 struct neighbour *n)
1325 char hbuffer[HBUFFERLEN];
1328 struct net_device *dev = n->dev;
1329 int hatype = dev->type;
1331 read_lock(&n->lock);
1332 /* Convert hardware address to XX:XX:XX:XX ... form. */
1333 #if IS_ENABLED(CONFIG_AX25)
1334 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1335 ax2asc2((ax25_address *)n->ha, hbuffer);
1338 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1339 hbuffer[k++] = hex_asc_hi(n->ha[j]);
1340 hbuffer[k++] = hex_asc_lo(n->ha[j]);
1346 #if IS_ENABLED(CONFIG_AX25)
1349 sprintf(tbuf, "%pI4", n->primary_key);
1350 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1351 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1352 read_unlock(&n->lock);
1355 static void arp_format_pneigh_entry(struct seq_file *seq,
1356 struct pneigh_entry *n)
1358 struct net_device *dev = n->dev;
1359 int hatype = dev ? dev->type : 0;
1362 sprintf(tbuf, "%pI4", n->key);
1363 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1364 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1365 dev ? dev->name : "*");
1368 static int arp_seq_show(struct seq_file *seq, void *v)
1370 if (v == SEQ_START_TOKEN) {
1371 seq_puts(seq, "IP address HW type Flags "
1372 "HW address Mask Device\n");
1374 struct neigh_seq_state *state = seq->private;
1376 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1377 arp_format_pneigh_entry(seq, v);
1379 arp_format_neigh_entry(seq, v);
1385 static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1387 /* Don't want to confuse "arp -a" w/ magic entries,
1388 * so we tell the generic iterator to skip NUD_NOARP.
1390 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1393 /* ------------------------------------------------------------------------ */
1395 static const struct seq_operations arp_seq_ops = {
1396 .start = arp_seq_start,
1397 .next = neigh_seq_next,
1398 .stop = neigh_seq_stop,
1399 .show = arp_seq_show,
1402 static int arp_seq_open(struct inode *inode, struct file *file)
1404 return seq_open_net(inode, file, &arp_seq_ops,
1405 sizeof(struct neigh_seq_state));
1408 static const struct file_operations arp_seq_fops = {
1409 .owner = THIS_MODULE,
1410 .open = arp_seq_open,
1412 .llseek = seq_lseek,
1413 .release = seq_release_net,
1417 static int __net_init arp_net_init(struct net *net)
1419 if (!proc_net_fops_create(net, "arp", S_IRUGO, &arp_seq_fops))
1424 static void __net_exit arp_net_exit(struct net *net)
1426 proc_net_remove(net, "arp");
1429 static struct pernet_operations arp_net_ops = {
1430 .init = arp_net_init,
1431 .exit = arp_net_exit,
1434 static int __init arp_proc_init(void)
1436 return register_pernet_subsys(&arp_net_ops);
1439 #else /* CONFIG_PROC_FS */
1441 static int __init arp_proc_init(void)
1446 #endif /* CONFIG_PROC_FS */