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 bool arp_key_eq(const struct neighbour *n, const void *pkey);
126 static int arp_constructor(struct neighbour *neigh);
127 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
128 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
129 static void parp_redo(struct sk_buff *skb);
131 static const struct neigh_ops arp_generic_ops = {
133 .solicit = arp_solicit,
134 .error_report = arp_error_report,
135 .output = neigh_resolve_output,
136 .connected_output = neigh_connected_output,
139 static const struct neigh_ops arp_hh_ops = {
141 .solicit = arp_solicit,
142 .error_report = arp_error_report,
143 .output = neigh_resolve_output,
144 .connected_output = neigh_resolve_output,
147 static const struct neigh_ops arp_direct_ops = {
149 .output = neigh_direct_output,
150 .connected_output = neigh_direct_output,
153 struct neigh_table arp_tbl = {
156 .protocol = cpu_to_be16(ETH_P_IP),
158 .key_eq = arp_key_eq,
159 .constructor = arp_constructor,
160 .proxy_redo = parp_redo,
164 .reachable_time = 30 * HZ,
166 [NEIGH_VAR_MCAST_PROBES] = 3,
167 [NEIGH_VAR_UCAST_PROBES] = 3,
168 [NEIGH_VAR_RETRANS_TIME] = 1 * HZ,
169 [NEIGH_VAR_BASE_REACHABLE_TIME] = 30 * HZ,
170 [NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ,
171 [NEIGH_VAR_GC_STALETIME] = 60 * HZ,
172 [NEIGH_VAR_QUEUE_LEN_BYTES] = 64 * 1024,
173 [NEIGH_VAR_PROXY_QLEN] = 64,
174 [NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ,
175 [NEIGH_VAR_PROXY_DELAY] = (8 * HZ) / 10,
176 [NEIGH_VAR_LOCKTIME] = 1 * HZ,
179 .gc_interval = 30 * HZ,
184 EXPORT_SYMBOL(arp_tbl);
186 int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir)
192 ip_eth_mc_map(addr, haddr);
194 case ARPHRD_INFINIBAND:
195 ip_ib_mc_map(addr, dev->broadcast, haddr);
198 ip_ipgre_mc_map(addr, dev->broadcast, haddr);
202 memcpy(haddr, dev->broadcast, dev->addr_len);
210 static u32 arp_hash(const void *pkey,
211 const struct net_device *dev,
214 return arp_hashfn(pkey, dev, hash_rnd);
217 static bool arp_key_eq(const struct neighbour *neigh, const void *pkey)
219 return neigh_key_eq32(neigh, pkey);
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);
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
263 if (neigh->type == RTN_MULTICAST) {
264 neigh->nud_state = NUD_NOARP;
265 arp_mc_map(addr, neigh->ha, dev, 1);
266 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) {
267 neigh->nud_state = NUD_NOARP;
268 memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
269 } else if (neigh->type == RTN_BROADCAST ||
270 (dev->flags & IFF_POINTOPOINT)) {
271 neigh->nud_state = NUD_NOARP;
272 memcpy(neigh->ha, dev->broadcast, dev->addr_len);
275 if (dev->header_ops->cache)
276 neigh->ops = &arp_hh_ops;
278 neigh->ops = &arp_generic_ops;
280 if (neigh->nud_state & NUD_VALID)
281 neigh->output = neigh->ops->connected_output;
283 neigh->output = neigh->ops->output;
288 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
290 dst_link_failure(skb);
294 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
297 u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL;
298 struct net_device *dev = neigh->dev;
299 __be32 target = *(__be32 *)neigh->primary_key;
300 int probes = atomic_read(&neigh->probes);
301 struct in_device *in_dev;
304 in_dev = __in_dev_get_rcu(dev);
309 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
311 case 0: /* By default announce any local IP */
312 if (skb && inet_addr_type(dev_net(dev),
313 ip_hdr(skb)->saddr) == RTN_LOCAL)
314 saddr = ip_hdr(skb)->saddr;
316 case 1: /* Restrict announcements of saddr in same subnet */
319 saddr = ip_hdr(skb)->saddr;
320 if (inet_addr_type(dev_net(dev), saddr) == RTN_LOCAL) {
321 /* saddr should be known to target */
322 if (inet_addr_onlink(in_dev, target, saddr))
327 case 2: /* Avoid secondary IPs, get a primary/preferred one */
333 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
335 probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES);
337 if (!(neigh->nud_state & NUD_VALID))
338 pr_debug("trying to ucast probe in NUD_INVALID\n");
339 neigh_ha_snapshot(dst_ha, neigh, dev);
342 probes -= NEIGH_VAR(neigh->parms, APP_PROBES);
349 arp_send(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
350 dst_hw, dev->dev_addr, NULL);
353 static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip)
355 struct net *net = dev_net(in_dev->dev);
358 switch (IN_DEV_ARP_IGNORE(in_dev)) {
359 case 0: /* Reply, the tip is already validated */
361 case 1: /* Reply only if tip is configured on the incoming interface */
363 scope = RT_SCOPE_HOST;
366 * Reply only if tip is configured on the incoming interface
367 * and is in same subnet as sip
369 scope = RT_SCOPE_HOST;
371 case 3: /* Do not reply for scope host addresses */
373 scope = RT_SCOPE_LINK;
376 case 4: /* Reserved */
381 case 8: /* Do not reply */
386 return !inet_confirm_addr(net, in_dev, sip, tip, scope);
389 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
393 /*unsigned long now; */
394 struct net *net = dev_net(dev);
396 rt = ip_route_output(net, sip, tip, 0, 0);
399 if (rt->dst.dev != dev) {
400 NET_INC_STATS_BH(net, LINUX_MIB_ARPFILTER);
408 * Check if we can use proxy ARP for this path
410 static inline int arp_fwd_proxy(struct in_device *in_dev,
411 struct net_device *dev, struct rtable *rt)
413 struct in_device *out_dev;
416 if (rt->dst.dev == dev)
419 if (!IN_DEV_PROXY_ARP(in_dev))
421 imi = IN_DEV_MEDIUM_ID(in_dev);
427 /* place to check for proxy_arp for routes */
429 out_dev = __in_dev_get_rcu(rt->dst.dev);
431 omi = IN_DEV_MEDIUM_ID(out_dev);
433 return omi != imi && omi != -1;
437 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
439 * RFC3069 supports proxy arp replies back to the same interface. This
440 * is done to support (ethernet) switch features, like RFC 3069, where
441 * the individual ports are not allowed to communicate with each
442 * other, BUT they are allowed to talk to the upstream router. As
443 * described in RFC 3069, it is possible to allow these hosts to
444 * communicate through the upstream router, by proxy_arp'ing.
446 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
448 * This technology is known by different names:
449 * In RFC 3069 it is called VLAN Aggregation.
450 * Cisco and Allied Telesyn call it Private VLAN.
451 * Hewlett-Packard call it Source-Port filtering or port-isolation.
452 * Ericsson call it MAC-Forced Forwarding (RFC Draft).
455 static inline int arp_fwd_pvlan(struct in_device *in_dev,
456 struct net_device *dev, struct rtable *rt,
457 __be32 sip, __be32 tip)
459 /* Private VLAN is only concerned about the same ethernet segment */
460 if (rt->dst.dev != dev)
463 /* Don't reply on self probes (often done by windowz boxes)*/
467 if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
474 * Interface to link layer: send routine and receive handler.
478 * Create an arp packet. If dest_hw is not set, we create a broadcast
481 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
482 struct net_device *dev, __be32 src_ip,
483 const unsigned char *dest_hw,
484 const unsigned char *src_hw,
485 const unsigned char *target_hw)
489 unsigned char *arp_ptr;
490 int hlen = LL_RESERVED_SPACE(dev);
491 int tlen = dev->needed_tailroom;
497 skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
501 skb_reserve(skb, hlen);
502 skb_reset_network_header(skb);
503 arp = (struct arphdr *) skb_put(skb, arp_hdr_len(dev));
505 skb->protocol = htons(ETH_P_ARP);
507 src_hw = dev->dev_addr;
509 dest_hw = dev->broadcast;
512 * Fill the device header for the ARP frame
514 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
518 * Fill out the arp protocol part.
520 * The arp hardware type should match the device type, except for FDDI,
521 * which (according to RFC 1390) should always equal 1 (Ethernet).
524 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
525 * DIX code for the protocol. Make these device structure fields.
529 arp->ar_hrd = htons(dev->type);
530 arp->ar_pro = htons(ETH_P_IP);
533 #if IS_ENABLED(CONFIG_AX25)
535 arp->ar_hrd = htons(ARPHRD_AX25);
536 arp->ar_pro = htons(AX25_P_IP);
539 #if IS_ENABLED(CONFIG_NETROM)
541 arp->ar_hrd = htons(ARPHRD_NETROM);
542 arp->ar_pro = htons(AX25_P_IP);
547 #if IS_ENABLED(CONFIG_FDDI)
549 arp->ar_hrd = htons(ARPHRD_ETHER);
550 arp->ar_pro = htons(ETH_P_IP);
555 arp->ar_hln = dev->addr_len;
557 arp->ar_op = htons(type);
559 arp_ptr = (unsigned char *)(arp + 1);
561 memcpy(arp_ptr, src_hw, dev->addr_len);
562 arp_ptr += dev->addr_len;
563 memcpy(arp_ptr, &src_ip, 4);
567 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
568 case ARPHRD_IEEE1394:
573 memcpy(arp_ptr, target_hw, dev->addr_len);
575 memset(arp_ptr, 0, dev->addr_len);
576 arp_ptr += dev->addr_len;
578 memcpy(arp_ptr, &dest_ip, 4);
586 EXPORT_SYMBOL(arp_create);
589 * Send an arp packet.
591 void arp_xmit(struct sk_buff *skb)
593 /* Send it off, maybe filter it using firewalling first. */
594 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, NULL, skb,
595 NULL, skb->dev, dev_queue_xmit_sk);
597 EXPORT_SYMBOL(arp_xmit);
600 * Create and send an arp packet.
602 void arp_send(int type, int ptype, __be32 dest_ip,
603 struct net_device *dev, __be32 src_ip,
604 const unsigned char *dest_hw, const unsigned char *src_hw,
605 const unsigned char *target_hw)
610 * No arp on this interface.
613 if (dev->flags&IFF_NOARP)
616 skb = arp_create(type, ptype, dest_ip, dev, src_ip,
617 dest_hw, src_hw, target_hw);
623 EXPORT_SYMBOL(arp_send);
626 * Process an arp request.
629 static int arp_process(struct sock *sk, struct sk_buff *skb)
631 struct net_device *dev = skb->dev;
632 struct in_device *in_dev = __in_dev_get_rcu(dev);
634 unsigned char *arp_ptr;
638 u16 dev_type = dev->type;
641 struct net *net = dev_net(dev);
642 bool is_garp = false;
644 /* arp_rcv below verifies the ARP header and verifies the device
655 if (arp->ar_pro != htons(ETH_P_IP) ||
656 htons(dev_type) != arp->ar_hrd)
663 * ETHERNET, and Fibre Channel (which are IEEE 802
664 * devices, according to RFC 2625) devices will accept ARP
665 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
666 * This is the case also of FDDI, where the RFC 1390 says that
667 * FDDI devices should accept ARP hardware of (1) Ethernet,
668 * however, to be more robust, we'll accept both 1 (Ethernet)
671 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
672 arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
673 arp->ar_pro != htons(ETH_P_IP))
677 if (arp->ar_pro != htons(AX25_P_IP) ||
678 arp->ar_hrd != htons(ARPHRD_AX25))
682 if (arp->ar_pro != htons(AX25_P_IP) ||
683 arp->ar_hrd != htons(ARPHRD_NETROM))
688 /* Understand only these message types */
690 if (arp->ar_op != htons(ARPOP_REPLY) &&
691 arp->ar_op != htons(ARPOP_REQUEST))
697 arp_ptr = (unsigned char *)(arp + 1);
699 arp_ptr += dev->addr_len;
700 memcpy(&sip, arp_ptr, 4);
703 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
704 case ARPHRD_IEEE1394:
708 arp_ptr += dev->addr_len;
710 memcpy(&tip, arp_ptr, 4);
712 * Check for bad requests for 127.x.x.x and requests for multicast
713 * addresses. If this is one such, delete it.
715 if (ipv4_is_multicast(tip) ||
716 (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip)))
720 * Special case: We must set Frame Relay source Q.922 address
722 if (dev_type == ARPHRD_DLCI)
723 sha = dev->broadcast;
726 * Process entry. The idea here is we want to send a reply if it is a
727 * request for us or if it is a request for someone else that we hold
728 * a proxy for. We want to add an entry to our cache if it is a reply
729 * to us or if it is a request for our address.
730 * (The assumption for this last is that if someone is requesting our
731 * address, they are probably intending to talk to us, so it saves time
732 * if we cache their address. Their address is also probably not in
733 * our cache, since ours is not in their cache.)
735 * Putting this another way, we only care about replies if they are to
736 * us, in which case we add them to the cache. For requests, we care
737 * about those for us and those for our proxies. We reply to both,
738 * and in the case of requests for us we add the requester to the arp
742 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
744 if (arp->ar_op == htons(ARPOP_REQUEST) &&
745 inet_addr_type(net, tip) == RTN_LOCAL &&
746 !arp_ignore(in_dev, sip, tip))
747 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, sha,
752 if (arp->ar_op == htons(ARPOP_REQUEST) &&
753 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
755 rt = skb_rtable(skb);
756 addr_type = rt->rt_type;
758 if (addr_type == RTN_LOCAL) {
761 dont_send = arp_ignore(in_dev, sip, tip);
762 if (!dont_send && IN_DEV_ARPFILTER(in_dev))
763 dont_send = arp_filter(sip, tip, dev);
765 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
767 arp_send(ARPOP_REPLY, ETH_P_ARP, sip,
768 dev, tip, sha, dev->dev_addr,
774 } else if (IN_DEV_FORWARD(in_dev)) {
775 if (addr_type == RTN_UNICAST &&
776 (arp_fwd_proxy(in_dev, dev, rt) ||
777 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
778 (rt->dst.dev != dev &&
779 pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
780 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
784 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
785 skb->pkt_type == PACKET_HOST ||
786 NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) {
787 arp_send(ARPOP_REPLY, ETH_P_ARP, sip,
788 dev, tip, sha, dev->dev_addr,
791 pneigh_enqueue(&arp_tbl,
792 in_dev->arp_parms, skb);
800 /* Update our ARP tables */
802 n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
804 if (IN_DEV_ARP_ACCEPT(in_dev)) {
805 /* Unsolicited ARP is not accepted by default.
806 It is possible, that this option should be enabled for some
807 devices (strip is candidate)
809 is_garp = arp->ar_op == htons(ARPOP_REQUEST) && tip == sip &&
810 inet_addr_type(net, sip) == RTN_UNICAST;
813 ((arp->ar_op == htons(ARPOP_REPLY) &&
814 inet_addr_type(net, sip) == RTN_UNICAST) || is_garp))
815 n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
819 int state = NUD_REACHABLE;
822 /* If several different ARP replies follows back-to-back,
823 use the FIRST one. It is possible, if several proxy
824 agents are active. Taking the first reply prevents
825 arp trashing and chooses the fastest router.
827 override = time_after(jiffies,
829 NEIGH_VAR(n->parms, LOCKTIME)) ||
832 /* Broadcast replies and request packets
833 do not assert neighbour reachability.
835 if (arp->ar_op != htons(ARPOP_REPLY) ||
836 skb->pkt_type != PACKET_HOST)
838 neigh_update(n, sha, state,
839 override ? NEIGH_UPDATE_F_OVERRIDE : 0);
848 static void parp_redo(struct sk_buff *skb)
850 arp_process(NULL, skb);
855 * Receive an arp request from the device layer.
858 static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
859 struct packet_type *pt, struct net_device *orig_dev)
861 const struct arphdr *arp;
863 /* do not tweak dropwatch on an ARP we will ignore */
864 if (dev->flags & IFF_NOARP ||
865 skb->pkt_type == PACKET_OTHERHOST ||
866 skb->pkt_type == PACKET_LOOPBACK)
869 skb = skb_share_check(skb, GFP_ATOMIC);
873 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
874 if (!pskb_may_pull(skb, arp_hdr_len(dev)))
878 if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4)
881 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
883 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, NULL, skb,
884 dev, NULL, arp_process);
896 * User level interface (ioctl)
900 * Set (create) an ARP cache entry.
903 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
906 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
909 if (__in_dev_get_rtnl(dev)) {
910 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
916 static int arp_req_set_public(struct net *net, struct arpreq *r,
917 struct net_device *dev)
919 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
920 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
922 if (mask && mask != htonl(0xFFFFFFFF))
924 if (!dev && (r->arp_flags & ATF_COM)) {
925 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family,
931 if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1))
936 return arp_req_set_proxy(net, dev, 1);
939 static int arp_req_set(struct net *net, struct arpreq *r,
940 struct net_device *dev)
943 struct neighbour *neigh;
946 if (r->arp_flags & ATF_PUBL)
947 return arp_req_set_public(net, r, dev);
949 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
950 if (r->arp_flags & ATF_PERM)
951 r->arp_flags |= ATF_COM;
953 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
963 #if IS_ENABLED(CONFIG_FDDI)
966 * According to RFC 1390, FDDI devices should accept ARP
967 * hardware types of 1 (Ethernet). However, to be more
968 * robust, we'll accept hardware types of either 1 (Ethernet)
971 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
972 r->arp_ha.sa_family != ARPHRD_ETHER &&
973 r->arp_ha.sa_family != ARPHRD_IEEE802)
978 if (r->arp_ha.sa_family != dev->type)
983 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
984 err = PTR_ERR(neigh);
985 if (!IS_ERR(neigh)) {
986 unsigned int state = NUD_STALE;
987 if (r->arp_flags & ATF_PERM)
988 state = NUD_PERMANENT;
989 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ?
990 r->arp_ha.sa_data : NULL, state,
991 NEIGH_UPDATE_F_OVERRIDE |
992 NEIGH_UPDATE_F_ADMIN);
993 neigh_release(neigh);
998 static unsigned int arp_state_to_flags(struct neighbour *neigh)
1000 if (neigh->nud_state&NUD_PERMANENT)
1001 return ATF_PERM | ATF_COM;
1002 else if (neigh->nud_state&NUD_VALID)
1009 * Get an ARP cache entry.
1012 static int arp_req_get(struct arpreq *r, struct net_device *dev)
1014 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1015 struct neighbour *neigh;
1018 neigh = neigh_lookup(&arp_tbl, &ip, dev);
1020 read_lock_bh(&neigh->lock);
1021 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
1022 r->arp_flags = arp_state_to_flags(neigh);
1023 read_unlock_bh(&neigh->lock);
1024 r->arp_ha.sa_family = dev->type;
1025 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1026 neigh_release(neigh);
1032 static int arp_invalidate(struct net_device *dev, __be32 ip)
1034 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
1038 if (neigh->nud_state & ~NUD_NOARP)
1039 err = neigh_update(neigh, NULL, NUD_FAILED,
1040 NEIGH_UPDATE_F_OVERRIDE|
1041 NEIGH_UPDATE_F_ADMIN);
1042 neigh_release(neigh);
1048 static int arp_req_delete_public(struct net *net, struct arpreq *r,
1049 struct net_device *dev)
1051 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1052 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1054 if (mask == htonl(0xFFFFFFFF))
1055 return pneigh_delete(&arp_tbl, net, &ip, dev);
1060 return arp_req_set_proxy(net, dev, 0);
1063 static int arp_req_delete(struct net *net, struct arpreq *r,
1064 struct net_device *dev)
1068 if (r->arp_flags & ATF_PUBL)
1069 return arp_req_delete_public(net, r, dev);
1071 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1073 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1081 return arp_invalidate(dev, ip);
1085 * Handle an ARP layer I/O control request.
1088 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1092 struct net_device *dev = NULL;
1097 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1100 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1108 if (r.arp_pa.sa_family != AF_INET)
1109 return -EPFNOSUPPORT;
1111 if (!(r.arp_flags & ATF_PUBL) &&
1112 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1114 if (!(r.arp_flags & ATF_NETMASK))
1115 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1116 htonl(0xFFFFFFFFUL);
1120 dev = __dev_get_by_name(net, r.arp_dev);
1124 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1125 if (!r.arp_ha.sa_family)
1126 r.arp_ha.sa_family = dev->type;
1128 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1130 } else if (cmd == SIOCGARP) {
1137 err = arp_req_delete(net, &r, dev);
1140 err = arp_req_set(net, &r, dev);
1143 err = arp_req_get(&r, dev);
1148 if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
1153 static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1156 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
1157 struct netdev_notifier_change_info *change_info;
1160 case NETDEV_CHANGEADDR:
1161 neigh_changeaddr(&arp_tbl, dev);
1162 rt_cache_flush(dev_net(dev));
1166 if (change_info->flags_changed & IFF_NOARP)
1167 neigh_changeaddr(&arp_tbl, dev);
1176 static struct notifier_block arp_netdev_notifier = {
1177 .notifier_call = arp_netdev_event,
1180 /* Note, that it is not on notifier chain.
1181 It is necessary, that this routine was called after route cache will be
1184 void arp_ifdown(struct net_device *dev)
1186 neigh_ifdown(&arp_tbl, dev);
1191 * Called once on startup.
1194 static struct packet_type arp_packet_type __read_mostly = {
1195 .type = cpu_to_be16(ETH_P_ARP),
1199 static int arp_proc_init(void);
1201 void __init arp_init(void)
1203 neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl);
1205 dev_add_pack(&arp_packet_type);
1207 #ifdef CONFIG_SYSCTL
1208 neigh_sysctl_register(NULL, &arp_tbl.parms, NULL);
1210 register_netdevice_notifier(&arp_netdev_notifier);
1213 #ifdef CONFIG_PROC_FS
1214 #if IS_ENABLED(CONFIG_AX25)
1216 /* ------------------------------------------------------------------------ */
1218 * ax25 -> ASCII conversion
1220 static char *ax2asc2(ax25_address *a, char *buf)
1225 for (n = 0, s = buf; n < 6; n++) {
1226 c = (a->ax25_call[n] >> 1) & 0x7F;
1233 n = (a->ax25_call[6] >> 1) & 0x0F;
1242 if (*buf == '\0' || *buf == '-')
1247 #endif /* CONFIG_AX25 */
1249 #define HBUFFERLEN 30
1251 static void arp_format_neigh_entry(struct seq_file *seq,
1252 struct neighbour *n)
1254 char hbuffer[HBUFFERLEN];
1257 struct net_device *dev = n->dev;
1258 int hatype = dev->type;
1260 read_lock(&n->lock);
1261 /* Convert hardware address to XX:XX:XX:XX ... form. */
1262 #if IS_ENABLED(CONFIG_AX25)
1263 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1264 ax2asc2((ax25_address *)n->ha, hbuffer);
1267 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1268 hbuffer[k++] = hex_asc_hi(n->ha[j]);
1269 hbuffer[k++] = hex_asc_lo(n->ha[j]);
1275 #if IS_ENABLED(CONFIG_AX25)
1278 sprintf(tbuf, "%pI4", n->primary_key);
1279 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1280 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1281 read_unlock(&n->lock);
1284 static void arp_format_pneigh_entry(struct seq_file *seq,
1285 struct pneigh_entry *n)
1287 struct net_device *dev = n->dev;
1288 int hatype = dev ? dev->type : 0;
1291 sprintf(tbuf, "%pI4", n->key);
1292 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1293 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1294 dev ? dev->name : "*");
1297 static int arp_seq_show(struct seq_file *seq, void *v)
1299 if (v == SEQ_START_TOKEN) {
1300 seq_puts(seq, "IP address HW type Flags "
1301 "HW address Mask Device\n");
1303 struct neigh_seq_state *state = seq->private;
1305 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1306 arp_format_pneigh_entry(seq, v);
1308 arp_format_neigh_entry(seq, v);
1314 static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1316 /* Don't want to confuse "arp -a" w/ magic entries,
1317 * so we tell the generic iterator to skip NUD_NOARP.
1319 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1322 /* ------------------------------------------------------------------------ */
1324 static const struct seq_operations arp_seq_ops = {
1325 .start = arp_seq_start,
1326 .next = neigh_seq_next,
1327 .stop = neigh_seq_stop,
1328 .show = arp_seq_show,
1331 static int arp_seq_open(struct inode *inode, struct file *file)
1333 return seq_open_net(inode, file, &arp_seq_ops,
1334 sizeof(struct neigh_seq_state));
1337 static const struct file_operations arp_seq_fops = {
1338 .owner = THIS_MODULE,
1339 .open = arp_seq_open,
1341 .llseek = seq_lseek,
1342 .release = seq_release_net,
1346 static int __net_init arp_net_init(struct net *net)
1348 if (!proc_create("arp", S_IRUGO, net->proc_net, &arp_seq_fops))
1353 static void __net_exit arp_net_exit(struct net *net)
1355 remove_proc_entry("arp", net->proc_net);
1358 static struct pernet_operations arp_net_ops = {
1359 .init = arp_net_init,
1360 .exit = arp_net_exit,
1363 static int __init arp_proc_init(void)
1365 return register_pernet_subsys(&arp_net_ops);
1368 #else /* CONFIG_PROC_FS */
1370 static int __init arp_proc_init(void)
1375 #endif /* CONFIG_PROC_FS */