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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
78 #include <linux/module.h>
79 #include <linux/types.h>
80 #include <linux/string.h>
81 #include <linux/kernel.h>
82 #include <linux/capability.h>
83 #include <linux/socket.h>
84 #include <linux/sockios.h>
85 #include <linux/errno.h>
88 #include <linux/inet.h>
89 #include <linux/inetdevice.h>
90 #include <linux/netdevice.h>
91 #include <linux/etherdevice.h>
92 #include <linux/fddidevice.h>
93 #include <linux/if_arp.h>
94 #include <linux/skbuff.h>
95 #include <linux/proc_fs.h>
96 #include <linux/seq_file.h>
97 #include <linux/stat.h>
98 #include <linux/init.h>
99 #include <linux/net.h>
100 #include <linux/rcupdate.h>
101 #include <linux/slab.h>
103 #include <linux/sysctl.h>
106 #include <net/net_namespace.h>
108 #include <net/icmp.h>
109 #include <net/route.h>
110 #include <net/protocol.h>
112 #include <net/sock.h>
114 #include <net/ax25.h>
115 #include <net/netrom.h>
117 #include <linux/uaccess.h>
119 #include <linux/netfilter_arp.h>
122 * Interface to generic neighbour cache.
124 static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd);
125 static int arp_constructor(struct neighbour *neigh);
126 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
127 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
128 static void parp_redo(struct sk_buff *skb);
130 static const struct neigh_ops arp_generic_ops = {
132 .solicit = arp_solicit,
133 .error_report = arp_error_report,
134 .output = neigh_resolve_output,
135 .connected_output = neigh_connected_output,
138 static const struct neigh_ops arp_hh_ops = {
140 .solicit = arp_solicit,
141 .error_report = arp_error_report,
142 .output = neigh_resolve_output,
143 .connected_output = neigh_resolve_output,
146 static const struct neigh_ops arp_direct_ops = {
148 .output = neigh_direct_output,
149 .connected_output = neigh_direct_output,
152 static const struct neigh_ops arp_broken_ops = {
154 .solicit = arp_solicit,
155 .error_report = arp_error_report,
156 .output = neigh_compat_output,
157 .connected_output = neigh_compat_output,
160 struct neigh_table arp_tbl = {
164 .constructor = arp_constructor,
165 .proxy_redo = parp_redo,
169 .base_reachable_time = 30 * HZ,
170 .retrans_time = 1 * HZ,
171 .gc_staletime = 60 * HZ,
172 .reachable_time = 30 * HZ,
173 .delay_probe_time = 5 * HZ,
174 .queue_len_bytes = 64*1024,
177 .anycast_delay = 1 * HZ,
178 .proxy_delay = (8 * HZ) / 10,
182 .gc_interval = 30 * HZ,
187 EXPORT_SYMBOL(arp_tbl);
189 int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir)
195 ip_eth_mc_map(addr, haddr);
197 case ARPHRD_INFINIBAND:
198 ip_ib_mc_map(addr, dev->broadcast, haddr);
201 ip_ipgre_mc_map(addr, dev->broadcast, haddr);
205 memcpy(haddr, dev->broadcast, dev->addr_len);
213 static u32 arp_hash(const void *pkey,
214 const struct net_device *dev,
217 return arp_hashfn(*(u32 *)pkey, dev, *hash_rnd);
220 static int arp_constructor(struct neighbour *neigh)
222 __be32 addr = *(__be32 *)neigh->primary_key;
223 struct net_device *dev = neigh->dev;
224 struct in_device *in_dev;
225 struct neigh_parms *parms;
228 in_dev = __in_dev_get_rcu(dev);
229 if (in_dev == NULL) {
234 neigh->type = inet_addr_type(dev_net(dev), addr);
236 parms = in_dev->arp_parms;
237 __neigh_parms_put(neigh->parms);
238 neigh->parms = neigh_parms_clone(parms);
241 if (!dev->header_ops) {
242 neigh->nud_state = NUD_NOARP;
243 neigh->ops = &arp_direct_ops;
244 neigh->output = neigh_direct_output;
246 /* Good devices (checked by reading texts, but only Ethernet is
249 ARPHRD_ETHER: (ethernet, apfddi)
252 ARPHRD_METRICOM: (strip)
256 ARPHRD_IPDDP will also work, if author repairs it.
257 I did not it, because this driver does not work even
262 /* So... these "amateur" devices are hopeless.
263 The only thing, that I can say now:
264 It is very sad that we need to keep ugly obsolete
265 code to make them happy.
267 They should be moved to more reasonable state, now
268 they use rebuild_header INSTEAD OF hard_start_xmit!!!
269 Besides that, they are sort of out of date
270 (a lot of redundant clones/copies, useless in 2.1),
271 I wonder why people believe that they work.
277 #if IS_ENABLED(CONFIG_AX25)
279 #if IS_ENABLED(CONFIG_NETROM)
282 neigh->ops = &arp_broken_ops;
283 neigh->output = neigh->ops->output;
290 if (neigh->type == RTN_MULTICAST) {
291 neigh->nud_state = NUD_NOARP;
292 arp_mc_map(addr, neigh->ha, dev, 1);
293 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) {
294 neigh->nud_state = NUD_NOARP;
295 memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
296 } else if (neigh->type == RTN_BROADCAST ||
297 (dev->flags & IFF_POINTOPOINT)) {
298 neigh->nud_state = NUD_NOARP;
299 memcpy(neigh->ha, dev->broadcast, dev->addr_len);
302 if (dev->header_ops->cache)
303 neigh->ops = &arp_hh_ops;
305 neigh->ops = &arp_generic_ops;
307 if (neigh->nud_state & NUD_VALID)
308 neigh->output = neigh->ops->connected_output;
310 neigh->output = neigh->ops->output;
315 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
317 dst_link_failure(skb);
321 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
324 u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL;
325 struct net_device *dev = neigh->dev;
326 __be32 target = *(__be32 *)neigh->primary_key;
327 int probes = atomic_read(&neigh->probes);
328 struct in_device *in_dev;
331 in_dev = __in_dev_get_rcu(dev);
336 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
338 case 0: /* By default announce any local IP */
339 if (skb && inet_addr_type(dev_net(dev),
340 ip_hdr(skb)->saddr) == RTN_LOCAL)
341 saddr = ip_hdr(skb)->saddr;
343 case 1: /* Restrict announcements of saddr in same subnet */
346 saddr = ip_hdr(skb)->saddr;
347 if (inet_addr_type(dev_net(dev), saddr) == RTN_LOCAL) {
348 /* saddr should be known to target */
349 if (inet_addr_onlink(in_dev, target, saddr))
354 case 2: /* Avoid secondary IPs, get a primary/preferred one */
360 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
362 probes -= neigh->parms->ucast_probes;
364 if (!(neigh->nud_state & NUD_VALID))
365 pr_debug("trying to ucast probe in NUD_INVALID\n");
366 neigh_ha_snapshot(dst_ha, neigh, dev);
369 probes -= neigh->parms->app_probes;
378 arp_send(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
379 dst_hw, dev->dev_addr, NULL);
382 static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip)
386 switch (IN_DEV_ARP_IGNORE(in_dev)) {
387 case 0: /* Reply, the tip is already validated */
389 case 1: /* Reply only if tip is configured on the incoming interface */
391 scope = RT_SCOPE_HOST;
394 * Reply only if tip is configured on the incoming interface
395 * and is in same subnet as sip
397 scope = RT_SCOPE_HOST;
399 case 3: /* Do not reply for scope host addresses */
401 scope = RT_SCOPE_LINK;
403 case 4: /* Reserved */
408 case 8: /* Do not reply */
413 return !inet_confirm_addr(in_dev, sip, tip, scope);
416 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
420 /*unsigned long now; */
421 struct net *net = dev_net(dev);
423 rt = ip_route_output(net, sip, tip, 0, 0);
426 if (rt->dst.dev != dev) {
427 NET_INC_STATS_BH(net, LINUX_MIB_ARPFILTER);
434 /* OBSOLETE FUNCTIONS */
437 * Find an arp mapping in the cache. If not found, post a request.
439 * It is very UGLY routine: it DOES NOT use skb->dst->neighbour,
440 * even if it exists. It is supposed that skb->dev was mangled
441 * by a virtual device (eql, shaper). Nobody but broken devices
442 * is allowed to use this function, it is scheduled to be removed. --ANK
445 static int arp_set_predefined(int addr_hint, unsigned char *haddr,
446 __be32 paddr, struct net_device *dev)
450 pr_debug("arp called for own IP address\n");
451 memcpy(haddr, dev->dev_addr, dev->addr_len);
454 arp_mc_map(paddr, haddr, dev, 1);
457 memcpy(haddr, dev->broadcast, dev->addr_len);
464 int arp_find(unsigned char *haddr, struct sk_buff *skb)
466 struct net_device *dev = skb->dev;
471 pr_debug("arp_find is called with dst==NULL\n");
476 paddr = rt_nexthop(skb_rtable(skb), ip_hdr(skb)->daddr);
477 if (arp_set_predefined(inet_addr_type(dev_net(dev), paddr), haddr,
481 n = __neigh_lookup(&arp_tbl, &paddr, dev, 1);
485 if (n->nud_state & NUD_VALID || neigh_event_send(n, skb) == 0) {
486 neigh_ha_snapshot(haddr, n, dev);
495 EXPORT_SYMBOL(arp_find);
497 /* END OF OBSOLETE FUNCTIONS */
500 * Check if we can use proxy ARP for this path
502 static inline int arp_fwd_proxy(struct in_device *in_dev,
503 struct net_device *dev, struct rtable *rt)
505 struct in_device *out_dev;
508 if (rt->dst.dev == dev)
511 if (!IN_DEV_PROXY_ARP(in_dev))
513 imi = IN_DEV_MEDIUM_ID(in_dev);
519 /* place to check for proxy_arp for routes */
521 out_dev = __in_dev_get_rcu(rt->dst.dev);
523 omi = IN_DEV_MEDIUM_ID(out_dev);
525 return omi != imi && omi != -1;
529 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
531 * RFC3069 supports proxy arp replies back to the same interface. This
532 * is done to support (ethernet) switch features, like RFC 3069, where
533 * the individual ports are not allowed to communicate with each
534 * other, BUT they are allowed to talk to the upstream router. As
535 * described in RFC 3069, it is possible to allow these hosts to
536 * communicate through the upstream router, by proxy_arp'ing.
538 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
540 * This technology is known by different names:
541 * In RFC 3069 it is called VLAN Aggregation.
542 * Cisco and Allied Telesyn call it Private VLAN.
543 * Hewlett-Packard call it Source-Port filtering or port-isolation.
544 * Ericsson call it MAC-Forced Forwarding (RFC Draft).
547 static inline int arp_fwd_pvlan(struct in_device *in_dev,
548 struct net_device *dev, struct rtable *rt,
549 __be32 sip, __be32 tip)
551 /* Private VLAN is only concerned about the same ethernet segment */
552 if (rt->dst.dev != dev)
555 /* Don't reply on self probes (often done by windowz boxes)*/
559 if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
566 * Interface to link layer: send routine and receive handler.
570 * Create an arp packet. If (dest_hw == NULL), we create a broadcast
573 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
574 struct net_device *dev, __be32 src_ip,
575 const unsigned char *dest_hw,
576 const unsigned char *src_hw,
577 const unsigned char *target_hw)
581 unsigned char *arp_ptr;
582 int hlen = LL_RESERVED_SPACE(dev);
583 int tlen = dev->needed_tailroom;
589 skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
593 skb_reserve(skb, hlen);
594 skb_reset_network_header(skb);
595 arp = (struct arphdr *) skb_put(skb, arp_hdr_len(dev));
597 skb->protocol = htons(ETH_P_ARP);
599 src_hw = dev->dev_addr;
601 dest_hw = dev->broadcast;
604 * Fill the device header for the ARP frame
606 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
610 * Fill out the arp protocol part.
612 * The arp hardware type should match the device type, except for FDDI,
613 * which (according to RFC 1390) should always equal 1 (Ethernet).
616 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
617 * DIX code for the protocol. Make these device structure fields.
621 arp->ar_hrd = htons(dev->type);
622 arp->ar_pro = htons(ETH_P_IP);
625 #if IS_ENABLED(CONFIG_AX25)
627 arp->ar_hrd = htons(ARPHRD_AX25);
628 arp->ar_pro = htons(AX25_P_IP);
631 #if IS_ENABLED(CONFIG_NETROM)
633 arp->ar_hrd = htons(ARPHRD_NETROM);
634 arp->ar_pro = htons(AX25_P_IP);
639 #if IS_ENABLED(CONFIG_FDDI)
641 arp->ar_hrd = htons(ARPHRD_ETHER);
642 arp->ar_pro = htons(ETH_P_IP);
647 arp->ar_hln = dev->addr_len;
649 arp->ar_op = htons(type);
651 arp_ptr = (unsigned char *)(arp + 1);
653 memcpy(arp_ptr, src_hw, dev->addr_len);
654 arp_ptr += dev->addr_len;
655 memcpy(arp_ptr, &src_ip, 4);
657 if (target_hw != NULL)
658 memcpy(arp_ptr, target_hw, dev->addr_len);
660 memset(arp_ptr, 0, dev->addr_len);
661 arp_ptr += dev->addr_len;
662 memcpy(arp_ptr, &dest_ip, 4);
670 EXPORT_SYMBOL(arp_create);
673 * Send an arp packet.
675 void arp_xmit(struct sk_buff *skb)
677 /* Send it off, maybe filter it using firewalling first. */
678 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, skb, NULL, skb->dev, dev_queue_xmit);
680 EXPORT_SYMBOL(arp_xmit);
683 * Create and send an arp packet.
685 void arp_send(int type, int ptype, __be32 dest_ip,
686 struct net_device *dev, __be32 src_ip,
687 const unsigned char *dest_hw, const unsigned char *src_hw,
688 const unsigned char *target_hw)
693 * No arp on this interface.
696 if (dev->flags&IFF_NOARP)
699 skb = arp_create(type, ptype, dest_ip, dev, src_ip,
700 dest_hw, src_hw, target_hw);
706 EXPORT_SYMBOL(arp_send);
709 * Process an arp request.
712 static int arp_process(struct sk_buff *skb)
714 struct net_device *dev = skb->dev;
715 struct in_device *in_dev = __in_dev_get_rcu(dev);
717 unsigned char *arp_ptr;
721 u16 dev_type = dev->type;
724 struct net *net = dev_net(dev);
726 /* arp_rcv below verifies the ARP header and verifies the device
737 if (arp->ar_pro != htons(ETH_P_IP) ||
738 htons(dev_type) != arp->ar_hrd)
745 * ETHERNET, and Fibre Channel (which are IEEE 802
746 * devices, according to RFC 2625) devices will accept ARP
747 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
748 * This is the case also of FDDI, where the RFC 1390 says that
749 * FDDI devices should accept ARP hardware of (1) Ethernet,
750 * however, to be more robust, we'll accept both 1 (Ethernet)
753 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
754 arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
755 arp->ar_pro != htons(ETH_P_IP))
759 if (arp->ar_pro != htons(AX25_P_IP) ||
760 arp->ar_hrd != htons(ARPHRD_AX25))
764 if (arp->ar_pro != htons(AX25_P_IP) ||
765 arp->ar_hrd != htons(ARPHRD_NETROM))
770 /* Understand only these message types */
772 if (arp->ar_op != htons(ARPOP_REPLY) &&
773 arp->ar_op != htons(ARPOP_REQUEST))
779 arp_ptr = (unsigned char *)(arp + 1);
781 arp_ptr += dev->addr_len;
782 memcpy(&sip, arp_ptr, 4);
784 arp_ptr += dev->addr_len;
785 memcpy(&tip, arp_ptr, 4);
787 * Check for bad requests for 127.x.x.x and requests for multicast
788 * addresses. If this is one such, delete it.
790 if (ipv4_is_multicast(tip) ||
791 (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip)))
795 * Special case: We must set Frame Relay source Q.922 address
797 if (dev_type == ARPHRD_DLCI)
798 sha = dev->broadcast;
801 * Process entry. The idea here is we want to send a reply if it is a
802 * request for us or if it is a request for someone else that we hold
803 * a proxy for. We want to add an entry to our cache if it is a reply
804 * to us or if it is a request for our address.
805 * (The assumption for this last is that if someone is requesting our
806 * address, they are probably intending to talk to us, so it saves time
807 * if we cache their address. Their address is also probably not in
808 * our cache, since ours is not in their cache.)
810 * Putting this another way, we only care about replies if they are to
811 * us, in which case we add them to the cache. For requests, we care
812 * about those for us and those for our proxies. We reply to both,
813 * and in the case of requests for us we add the requester to the arp
817 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
819 if (arp->ar_op == htons(ARPOP_REQUEST) &&
820 inet_addr_type(net, tip) == RTN_LOCAL &&
821 !arp_ignore(in_dev, sip, tip))
822 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, sha,
827 if (arp->ar_op == htons(ARPOP_REQUEST) &&
828 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
830 rt = skb_rtable(skb);
831 addr_type = rt->rt_type;
833 if (addr_type == RTN_LOCAL) {
836 dont_send = arp_ignore(in_dev, sip, tip);
837 if (!dont_send && IN_DEV_ARPFILTER(in_dev))
838 dont_send = arp_filter(sip, tip, dev);
840 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
842 arp_send(ARPOP_REPLY, ETH_P_ARP, sip,
843 dev, tip, sha, dev->dev_addr,
849 } else if (IN_DEV_FORWARD(in_dev)) {
850 if (addr_type == RTN_UNICAST &&
851 (arp_fwd_proxy(in_dev, dev, rt) ||
852 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
853 (rt->dst.dev != dev &&
854 pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
855 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
859 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
860 skb->pkt_type == PACKET_HOST ||
861 in_dev->arp_parms->proxy_delay == 0) {
862 arp_send(ARPOP_REPLY, ETH_P_ARP, sip,
863 dev, tip, sha, dev->dev_addr,
866 pneigh_enqueue(&arp_tbl,
867 in_dev->arp_parms, skb);
875 /* Update our ARP tables */
877 n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
879 if (IN_DEV_ARP_ACCEPT(in_dev)) {
880 /* Unsolicited ARP is not accepted by default.
881 It is possible, that this option should be enabled for some
882 devices (strip is candidate)
885 (arp->ar_op == htons(ARPOP_REPLY) ||
886 (arp->ar_op == htons(ARPOP_REQUEST) && tip == sip)) &&
887 inet_addr_type(net, sip) == RTN_UNICAST)
888 n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
892 int state = NUD_REACHABLE;
895 /* If several different ARP replies follows back-to-back,
896 use the FIRST one. It is possible, if several proxy
897 agents are active. Taking the first reply prevents
898 arp trashing and chooses the fastest router.
900 override = time_after(jiffies, n->updated + n->parms->locktime);
902 /* Broadcast replies and request packets
903 do not assert neighbour reachability.
905 if (arp->ar_op != htons(ARPOP_REPLY) ||
906 skb->pkt_type != PACKET_HOST)
908 neigh_update(n, sha, state,
909 override ? NEIGH_UPDATE_F_OVERRIDE : 0);
918 static void parp_redo(struct sk_buff *skb)
925 * Receive an arp request from the device layer.
928 static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
929 struct packet_type *pt, struct net_device *orig_dev)
933 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
934 if (!pskb_may_pull(skb, arp_hdr_len(dev)))
938 if (arp->ar_hln != dev->addr_len ||
939 dev->flags & IFF_NOARP ||
940 skb->pkt_type == PACKET_OTHERHOST ||
941 skb->pkt_type == PACKET_LOOPBACK ||
945 skb = skb_share_check(skb, GFP_ATOMIC);
949 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
951 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, skb, dev, NULL, arp_process);
960 * User level interface (ioctl)
964 * Set (create) an ARP cache entry.
967 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
970 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
973 if (__in_dev_get_rtnl(dev)) {
974 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
980 static int arp_req_set_public(struct net *net, struct arpreq *r,
981 struct net_device *dev)
983 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
984 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
986 if (mask && mask != htonl(0xFFFFFFFF))
988 if (!dev && (r->arp_flags & ATF_COM)) {
989 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family,
995 if (pneigh_lookup(&arp_tbl, net, &ip, dev, 1) == NULL)
1000 return arp_req_set_proxy(net, dev, 1);
1003 static int arp_req_set(struct net *net, struct arpreq *r,
1004 struct net_device *dev)
1007 struct neighbour *neigh;
1010 if (r->arp_flags & ATF_PUBL)
1011 return arp_req_set_public(net, r, dev);
1013 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1014 if (r->arp_flags & ATF_PERM)
1015 r->arp_flags |= ATF_COM;
1017 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1026 switch (dev->type) {
1027 #if IS_ENABLED(CONFIG_FDDI)
1030 * According to RFC 1390, FDDI devices should accept ARP
1031 * hardware types of 1 (Ethernet). However, to be more
1032 * robust, we'll accept hardware types of either 1 (Ethernet)
1033 * or 6 (IEEE 802.2).
1035 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1036 r->arp_ha.sa_family != ARPHRD_ETHER &&
1037 r->arp_ha.sa_family != ARPHRD_IEEE802)
1042 if (r->arp_ha.sa_family != dev->type)
1047 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1048 err = PTR_ERR(neigh);
1049 if (!IS_ERR(neigh)) {
1050 unsigned int state = NUD_STALE;
1051 if (r->arp_flags & ATF_PERM)
1052 state = NUD_PERMANENT;
1053 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ?
1054 r->arp_ha.sa_data : NULL, state,
1055 NEIGH_UPDATE_F_OVERRIDE |
1056 NEIGH_UPDATE_F_ADMIN);
1057 neigh_release(neigh);
1062 static unsigned int arp_state_to_flags(struct neighbour *neigh)
1064 if (neigh->nud_state&NUD_PERMANENT)
1065 return ATF_PERM | ATF_COM;
1066 else if (neigh->nud_state&NUD_VALID)
1073 * Get an ARP cache entry.
1076 static int arp_req_get(struct arpreq *r, struct net_device *dev)
1078 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1079 struct neighbour *neigh;
1082 neigh = neigh_lookup(&arp_tbl, &ip, dev);
1084 read_lock_bh(&neigh->lock);
1085 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
1086 r->arp_flags = arp_state_to_flags(neigh);
1087 read_unlock_bh(&neigh->lock);
1088 r->arp_ha.sa_family = dev->type;
1089 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1090 neigh_release(neigh);
1096 int arp_invalidate(struct net_device *dev, __be32 ip)
1098 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
1102 if (neigh->nud_state & ~NUD_NOARP)
1103 err = neigh_update(neigh, NULL, NUD_FAILED,
1104 NEIGH_UPDATE_F_OVERRIDE|
1105 NEIGH_UPDATE_F_ADMIN);
1106 neigh_release(neigh);
1111 EXPORT_SYMBOL(arp_invalidate);
1113 static int arp_req_delete_public(struct net *net, struct arpreq *r,
1114 struct net_device *dev)
1116 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1117 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1119 if (mask == htonl(0xFFFFFFFF))
1120 return pneigh_delete(&arp_tbl, net, &ip, dev);
1125 return arp_req_set_proxy(net, dev, 0);
1128 static int arp_req_delete(struct net *net, struct arpreq *r,
1129 struct net_device *dev)
1133 if (r->arp_flags & ATF_PUBL)
1134 return arp_req_delete_public(net, r, dev);
1136 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1138 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1146 return arp_invalidate(dev, ip);
1150 * Handle an ARP layer I/O control request.
1153 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1157 struct net_device *dev = NULL;
1162 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1165 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1173 if (r.arp_pa.sa_family != AF_INET)
1174 return -EPFNOSUPPORT;
1176 if (!(r.arp_flags & ATF_PUBL) &&
1177 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1179 if (!(r.arp_flags & ATF_NETMASK))
1180 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1181 htonl(0xFFFFFFFFUL);
1185 dev = __dev_get_by_name(net, r.arp_dev);
1189 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1190 if (!r.arp_ha.sa_family)
1191 r.arp_ha.sa_family = dev->type;
1193 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1195 } else if (cmd == SIOCGARP) {
1202 err = arp_req_delete(net, &r, dev);
1205 err = arp_req_set(net, &r, dev);
1208 err = arp_req_get(&r, dev);
1213 if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
1218 static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1221 struct net_device *dev = ptr;
1224 case NETDEV_CHANGEADDR:
1225 neigh_changeaddr(&arp_tbl, dev);
1226 rt_cache_flush(dev_net(dev));
1235 static struct notifier_block arp_netdev_notifier = {
1236 .notifier_call = arp_netdev_event,
1239 /* Note, that it is not on notifier chain.
1240 It is necessary, that this routine was called after route cache will be
1243 void arp_ifdown(struct net_device *dev)
1245 neigh_ifdown(&arp_tbl, dev);
1250 * Called once on startup.
1253 static struct packet_type arp_packet_type __read_mostly = {
1254 .type = cpu_to_be16(ETH_P_ARP),
1258 static int arp_proc_init(void);
1260 void __init arp_init(void)
1262 neigh_table_init(&arp_tbl);
1264 dev_add_pack(&arp_packet_type);
1266 #ifdef CONFIG_SYSCTL
1267 neigh_sysctl_register(NULL, &arp_tbl.parms, "ipv4", NULL);
1269 register_netdevice_notifier(&arp_netdev_notifier);
1272 #ifdef CONFIG_PROC_FS
1273 #if IS_ENABLED(CONFIG_AX25)
1275 /* ------------------------------------------------------------------------ */
1277 * ax25 -> ASCII conversion
1279 static char *ax2asc2(ax25_address *a, char *buf)
1284 for (n = 0, s = buf; n < 6; n++) {
1285 c = (a->ax25_call[n] >> 1) & 0x7F;
1292 n = (a->ax25_call[6] >> 1) & 0x0F;
1301 if (*buf == '\0' || *buf == '-')
1306 #endif /* CONFIG_AX25 */
1308 #define HBUFFERLEN 30
1310 static void arp_format_neigh_entry(struct seq_file *seq,
1311 struct neighbour *n)
1313 char hbuffer[HBUFFERLEN];
1316 struct net_device *dev = n->dev;
1317 int hatype = dev->type;
1319 read_lock(&n->lock);
1320 /* Convert hardware address to XX:XX:XX:XX ... form. */
1321 #if IS_ENABLED(CONFIG_AX25)
1322 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1323 ax2asc2((ax25_address *)n->ha, hbuffer);
1326 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1327 hbuffer[k++] = hex_asc_hi(n->ha[j]);
1328 hbuffer[k++] = hex_asc_lo(n->ha[j]);
1334 #if IS_ENABLED(CONFIG_AX25)
1337 sprintf(tbuf, "%pI4", n->primary_key);
1338 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1339 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1340 read_unlock(&n->lock);
1343 static void arp_format_pneigh_entry(struct seq_file *seq,
1344 struct pneigh_entry *n)
1346 struct net_device *dev = n->dev;
1347 int hatype = dev ? dev->type : 0;
1350 sprintf(tbuf, "%pI4", n->key);
1351 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1352 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1353 dev ? dev->name : "*");
1356 static int arp_seq_show(struct seq_file *seq, void *v)
1358 if (v == SEQ_START_TOKEN) {
1359 seq_puts(seq, "IP address HW type Flags "
1360 "HW address Mask Device\n");
1362 struct neigh_seq_state *state = seq->private;
1364 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1365 arp_format_pneigh_entry(seq, v);
1367 arp_format_neigh_entry(seq, v);
1373 static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1375 /* Don't want to confuse "arp -a" w/ magic entries,
1376 * so we tell the generic iterator to skip NUD_NOARP.
1378 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1381 /* ------------------------------------------------------------------------ */
1383 static const struct seq_operations arp_seq_ops = {
1384 .start = arp_seq_start,
1385 .next = neigh_seq_next,
1386 .stop = neigh_seq_stop,
1387 .show = arp_seq_show,
1390 static int arp_seq_open(struct inode *inode, struct file *file)
1392 return seq_open_net(inode, file, &arp_seq_ops,
1393 sizeof(struct neigh_seq_state));
1396 static const struct file_operations arp_seq_fops = {
1397 .owner = THIS_MODULE,
1398 .open = arp_seq_open,
1400 .llseek = seq_lseek,
1401 .release = seq_release_net,
1405 static int __net_init arp_net_init(struct net *net)
1407 if (!proc_net_fops_create(net, "arp", S_IRUGO, &arp_seq_fops))
1412 static void __net_exit arp_net_exit(struct net *net)
1414 proc_net_remove(net, "arp");
1417 static struct pernet_operations arp_net_ops = {
1418 .init = arp_net_init,
1419 .exit = arp_net_exit,
1422 static int __init arp_proc_init(void)
1424 return register_pernet_subsys(&arp_net_ops);
1427 #else /* CONFIG_PROC_FS */
1429 static int __init arp_proc_init(void)
1434 #endif /* CONFIG_PROC_FS */