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
;
376 arp_send(ARPOP_REQUEST
, ETH_P_ARP
, target
, dev
, saddr
,
377 dst_hw
, dev
->dev_addr
, NULL
);
380 static int arp_ignore(struct in_device
*in_dev
, __be32 sip
, __be32 tip
)
384 switch (IN_DEV_ARP_IGNORE(in_dev
)) {
385 case 0: /* Reply, the tip is already validated */
387 case 1: /* Reply only if tip is configured on the incoming interface */
389 scope
= RT_SCOPE_HOST
;
392 * Reply only if tip is configured on the incoming interface
393 * and is in same subnet as sip
395 scope
= RT_SCOPE_HOST
;
397 case 3: /* Do not reply for scope host addresses */
399 scope
= RT_SCOPE_LINK
;
401 case 4: /* Reserved */
406 case 8: /* Do not reply */
411 return !inet_confirm_addr(in_dev
, sip
, tip
, scope
);
414 static int arp_filter(__be32 sip
, __be32 tip
, struct net_device
*dev
)
418 /*unsigned long now; */
419 struct net
*net
= dev_net(dev
);
421 rt
= ip_route_output(net
, sip
, tip
, 0, 0);
424 if (rt
->dst
.dev
!= dev
) {
425 NET_INC_STATS_BH(net
, LINUX_MIB_ARPFILTER
);
432 /* OBSOLETE FUNCTIONS */
435 * Find an arp mapping in the cache. If not found, post a request.
437 * It is very UGLY routine: it DOES NOT use skb->dst->neighbour,
438 * even if it exists. It is supposed that skb->dev was mangled
439 * by a virtual device (eql, shaper). Nobody but broken devices
440 * is allowed to use this function, it is scheduled to be removed. --ANK
443 static int arp_set_predefined(int addr_hint
, unsigned char *haddr
,
444 __be32 paddr
, struct net_device
*dev
)
448 pr_debug("arp called for own IP address\n");
449 memcpy(haddr
, dev
->dev_addr
, dev
->addr_len
);
452 arp_mc_map(paddr
, haddr
, dev
, 1);
455 memcpy(haddr
, dev
->broadcast
, dev
->addr_len
);
462 int arp_find(unsigned char *haddr
, struct sk_buff
*skb
)
464 struct net_device
*dev
= skb
->dev
;
469 pr_debug("arp_find is called with dst==NULL\n");
474 paddr
= rt_nexthop(skb_rtable(skb
), ip_hdr(skb
)->daddr
);
475 if (arp_set_predefined(inet_addr_type(dev_net(dev
), paddr
), haddr
,
479 n
= __neigh_lookup(&arp_tbl
, &paddr
, dev
, 1);
483 if (n
->nud_state
& NUD_VALID
|| neigh_event_send(n
, skb
) == 0) {
484 neigh_ha_snapshot(haddr
, n
, dev
);
493 EXPORT_SYMBOL(arp_find
);
495 /* END OF OBSOLETE FUNCTIONS */
498 * Check if we can use proxy ARP for this path
500 static inline int arp_fwd_proxy(struct in_device
*in_dev
,
501 struct net_device
*dev
, struct rtable
*rt
)
503 struct in_device
*out_dev
;
506 if (rt
->dst
.dev
== dev
)
509 if (!IN_DEV_PROXY_ARP(in_dev
))
511 imi
= IN_DEV_MEDIUM_ID(in_dev
);
517 /* place to check for proxy_arp for routes */
519 out_dev
= __in_dev_get_rcu(rt
->dst
.dev
);
521 omi
= IN_DEV_MEDIUM_ID(out_dev
);
523 return omi
!= imi
&& omi
!= -1;
527 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
529 * RFC3069 supports proxy arp replies back to the same interface. This
530 * is done to support (ethernet) switch features, like RFC 3069, where
531 * the individual ports are not allowed to communicate with each
532 * other, BUT they are allowed to talk to the upstream router. As
533 * described in RFC 3069, it is possible to allow these hosts to
534 * communicate through the upstream router, by proxy_arp'ing.
536 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
538 * This technology is known by different names:
539 * In RFC 3069 it is called VLAN Aggregation.
540 * Cisco and Allied Telesyn call it Private VLAN.
541 * Hewlett-Packard call it Source-Port filtering or port-isolation.
542 * Ericsson call it MAC-Forced Forwarding (RFC Draft).
545 static inline int arp_fwd_pvlan(struct in_device
*in_dev
,
546 struct net_device
*dev
, struct rtable
*rt
,
547 __be32 sip
, __be32 tip
)
549 /* Private VLAN is only concerned about the same ethernet segment */
550 if (rt
->dst
.dev
!= dev
)
553 /* Don't reply on self probes (often done by windowz boxes)*/
557 if (IN_DEV_PROXY_ARP_PVLAN(in_dev
))
564 * Interface to link layer: send routine and receive handler.
568 * Create an arp packet. If (dest_hw == NULL), we create a broadcast
571 struct sk_buff
*arp_create(int type
, int ptype
, __be32 dest_ip
,
572 struct net_device
*dev
, __be32 src_ip
,
573 const unsigned char *dest_hw
,
574 const unsigned char *src_hw
,
575 const unsigned char *target_hw
)
579 unsigned char *arp_ptr
;
580 int hlen
= LL_RESERVED_SPACE(dev
);
581 int tlen
= dev
->needed_tailroom
;
587 skb
= alloc_skb(arp_hdr_len(dev
) + hlen
+ tlen
, GFP_ATOMIC
);
591 skb_reserve(skb
, hlen
);
592 skb_reset_network_header(skb
);
593 arp
= (struct arphdr
*) skb_put(skb
, arp_hdr_len(dev
));
595 skb
->protocol
= htons(ETH_P_ARP
);
597 src_hw
= dev
->dev_addr
;
599 dest_hw
= dev
->broadcast
;
602 * Fill the device header for the ARP frame
604 if (dev_hard_header(skb
, dev
, ptype
, dest_hw
, src_hw
, skb
->len
) < 0)
608 * Fill out the arp protocol part.
610 * The arp hardware type should match the device type, except for FDDI,
611 * which (according to RFC 1390) should always equal 1 (Ethernet).
614 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
615 * DIX code for the protocol. Make these device structure fields.
619 arp
->ar_hrd
= htons(dev
->type
);
620 arp
->ar_pro
= htons(ETH_P_IP
);
623 #if IS_ENABLED(CONFIG_AX25)
625 arp
->ar_hrd
= htons(ARPHRD_AX25
);
626 arp
->ar_pro
= htons(AX25_P_IP
);
629 #if IS_ENABLED(CONFIG_NETROM)
631 arp
->ar_hrd
= htons(ARPHRD_NETROM
);
632 arp
->ar_pro
= htons(AX25_P_IP
);
637 #if IS_ENABLED(CONFIG_FDDI)
639 arp
->ar_hrd
= htons(ARPHRD_ETHER
);
640 arp
->ar_pro
= htons(ETH_P_IP
);
645 arp
->ar_hln
= dev
->addr_len
;
647 arp
->ar_op
= htons(type
);
649 arp_ptr
= (unsigned char *)(arp
+ 1);
651 memcpy(arp_ptr
, src_hw
, dev
->addr_len
);
652 arp_ptr
+= dev
->addr_len
;
653 memcpy(arp_ptr
, &src_ip
, 4);
657 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
658 case ARPHRD_IEEE1394
:
662 if (target_hw
!= NULL
)
663 memcpy(arp_ptr
, target_hw
, dev
->addr_len
);
665 memset(arp_ptr
, 0, dev
->addr_len
);
666 arp_ptr
+= dev
->addr_len
;
668 memcpy(arp_ptr
, &dest_ip
, 4);
676 EXPORT_SYMBOL(arp_create
);
679 * Send an arp packet.
681 void arp_xmit(struct sk_buff
*skb
)
683 /* Send it off, maybe filter it using firewalling first. */
684 NF_HOOK(NFPROTO_ARP
, NF_ARP_OUT
, skb
, NULL
, skb
->dev
, dev_queue_xmit
);
686 EXPORT_SYMBOL(arp_xmit
);
689 * Create and send an arp packet.
691 void arp_send(int type
, int ptype
, __be32 dest_ip
,
692 struct net_device
*dev
, __be32 src_ip
,
693 const unsigned char *dest_hw
, const unsigned char *src_hw
,
694 const unsigned char *target_hw
)
699 * No arp on this interface.
702 if (dev
->flags
&IFF_NOARP
)
705 skb
= arp_create(type
, ptype
, dest_ip
, dev
, src_ip
,
706 dest_hw
, src_hw
, target_hw
);
712 EXPORT_SYMBOL(arp_send
);
715 * Process an arp request.
718 static int arp_process(struct sk_buff
*skb
)
720 struct net_device
*dev
= skb
->dev
;
721 struct in_device
*in_dev
= __in_dev_get_rcu(dev
);
723 unsigned char *arp_ptr
;
727 u16 dev_type
= dev
->type
;
730 struct net
*net
= dev_net(dev
);
732 /* arp_rcv below verifies the ARP header and verifies the device
743 if (arp
->ar_pro
!= htons(ETH_P_IP
) ||
744 htons(dev_type
) != arp
->ar_hrd
)
751 * ETHERNET, and Fibre Channel (which are IEEE 802
752 * devices, according to RFC 2625) devices will accept ARP
753 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
754 * This is the case also of FDDI, where the RFC 1390 says that
755 * FDDI devices should accept ARP hardware of (1) Ethernet,
756 * however, to be more robust, we'll accept both 1 (Ethernet)
759 if ((arp
->ar_hrd
!= htons(ARPHRD_ETHER
) &&
760 arp
->ar_hrd
!= htons(ARPHRD_IEEE802
)) ||
761 arp
->ar_pro
!= htons(ETH_P_IP
))
765 if (arp
->ar_pro
!= htons(AX25_P_IP
) ||
766 arp
->ar_hrd
!= htons(ARPHRD_AX25
))
770 if (arp
->ar_pro
!= htons(AX25_P_IP
) ||
771 arp
->ar_hrd
!= htons(ARPHRD_NETROM
))
776 /* Understand only these message types */
778 if (arp
->ar_op
!= htons(ARPOP_REPLY
) &&
779 arp
->ar_op
!= htons(ARPOP_REQUEST
))
785 arp_ptr
= (unsigned char *)(arp
+ 1);
787 arp_ptr
+= dev
->addr_len
;
788 memcpy(&sip
, arp_ptr
, 4);
791 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
792 case ARPHRD_IEEE1394
:
796 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_multicast(tip
) ||
804 (!IN_DEV_ROUTE_LOCALNET(in_dev
) && ipv4_is_loopback(tip
)))
808 * Special case: We must set Frame Relay source Q.922 address
810 if (dev_type
== ARPHRD_DLCI
)
811 sha
= dev
->broadcast
;
814 * Process entry. The idea here is we want to send a reply if it is a
815 * request for us or if it is a request for someone else that we hold
816 * a proxy for. We want to add an entry to our cache if it is a reply
817 * to us or if it is a request for our address.
818 * (The assumption for this last is that if someone is requesting our
819 * address, they are probably intending to talk to us, so it saves time
820 * if we cache their address. Their address is also probably not in
821 * our cache, since ours is not in their cache.)
823 * Putting this another way, we only care about replies if they are to
824 * us, in which case we add them to the cache. For requests, we care
825 * about those for us and those for our proxies. We reply to both,
826 * and in the case of requests for us we add the requester to the arp
830 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
832 if (arp
->ar_op
== htons(ARPOP_REQUEST
) &&
833 inet_addr_type(net
, tip
) == RTN_LOCAL
&&
834 !arp_ignore(in_dev
, sip
, tip
))
835 arp_send(ARPOP_REPLY
, ETH_P_ARP
, sip
, dev
, tip
, sha
,
840 if (arp
->ar_op
== htons(ARPOP_REQUEST
) &&
841 ip_route_input_noref(skb
, tip
, sip
, 0, dev
) == 0) {
843 rt
= skb_rtable(skb
);
844 addr_type
= rt
->rt_type
;
846 if (addr_type
== RTN_LOCAL
) {
849 dont_send
= arp_ignore(in_dev
, sip
, tip
);
850 if (!dont_send
&& IN_DEV_ARPFILTER(in_dev
))
851 dont_send
= arp_filter(sip
, tip
, dev
);
853 n
= neigh_event_ns(&arp_tbl
, sha
, &sip
, dev
);
855 arp_send(ARPOP_REPLY
, ETH_P_ARP
, sip
,
856 dev
, tip
, sha
, dev
->dev_addr
,
862 } else if (IN_DEV_FORWARD(in_dev
)) {
863 if (addr_type
== RTN_UNICAST
&&
864 (arp_fwd_proxy(in_dev
, dev
, rt
) ||
865 arp_fwd_pvlan(in_dev
, dev
, rt
, sip
, tip
) ||
866 (rt
->dst
.dev
!= dev
&&
867 pneigh_lookup(&arp_tbl
, net
, &tip
, dev
, 0)))) {
868 n
= neigh_event_ns(&arp_tbl
, sha
, &sip
, dev
);
872 if (NEIGH_CB(skb
)->flags
& LOCALLY_ENQUEUED
||
873 skb
->pkt_type
== PACKET_HOST
||
874 in_dev
->arp_parms
->proxy_delay
== 0) {
875 arp_send(ARPOP_REPLY
, ETH_P_ARP
, sip
,
876 dev
, tip
, sha
, dev
->dev_addr
,
879 pneigh_enqueue(&arp_tbl
,
880 in_dev
->arp_parms
, skb
);
888 /* Update our ARP tables */
890 n
= __neigh_lookup(&arp_tbl
, &sip
, dev
, 0);
892 if (IN_DEV_ARP_ACCEPT(in_dev
)) {
893 /* Unsolicited ARP is not accepted by default.
894 It is possible, that this option should be enabled for some
895 devices (strip is candidate)
898 (arp
->ar_op
== htons(ARPOP_REPLY
) ||
899 (arp
->ar_op
== htons(ARPOP_REQUEST
) && tip
== sip
)) &&
900 inet_addr_type(net
, sip
) == RTN_UNICAST
)
901 n
= __neigh_lookup(&arp_tbl
, &sip
, dev
, 1);
905 int state
= NUD_REACHABLE
;
908 /* If several different ARP replies follows back-to-back,
909 use the FIRST one. It is possible, if several proxy
910 agents are active. Taking the first reply prevents
911 arp trashing and chooses the fastest router.
913 override
= time_after(jiffies
, n
->updated
+ n
->parms
->locktime
);
915 /* Broadcast replies and request packets
916 do not assert neighbour reachability.
918 if (arp
->ar_op
!= htons(ARPOP_REPLY
) ||
919 skb
->pkt_type
!= PACKET_HOST
)
921 neigh_update(n
, sha
, state
,
922 override
? NEIGH_UPDATE_F_OVERRIDE
: 0);
931 static void parp_redo(struct sk_buff
*skb
)
938 * Receive an arp request from the device layer.
941 static int arp_rcv(struct sk_buff
*skb
, struct net_device
*dev
,
942 struct packet_type
*pt
, struct net_device
*orig_dev
)
944 const struct arphdr
*arp
;
946 if (dev
->flags
& IFF_NOARP
||
947 skb
->pkt_type
== PACKET_OTHERHOST
||
948 skb
->pkt_type
== PACKET_LOOPBACK
)
951 skb
= skb_share_check(skb
, GFP_ATOMIC
);
955 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
956 if (!pskb_may_pull(skb
, arp_hdr_len(dev
)))
960 if (arp
->ar_hln
!= dev
->addr_len
|| arp
->ar_pln
!= 4)
963 memset(NEIGH_CB(skb
), 0, sizeof(struct neighbour_cb
));
965 return NF_HOOK(NFPROTO_ARP
, NF_ARP_IN
, skb
, dev
, NULL
, arp_process
);
974 * User level interface (ioctl)
978 * Set (create) an ARP cache entry.
981 static int arp_req_set_proxy(struct net
*net
, struct net_device
*dev
, int on
)
984 IPV4_DEVCONF_ALL(net
, PROXY_ARP
) = on
;
987 if (__in_dev_get_rtnl(dev
)) {
988 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev
), PROXY_ARP
, on
);
994 static int arp_req_set_public(struct net
*net
, struct arpreq
*r
,
995 struct net_device
*dev
)
997 __be32 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
998 __be32 mask
= ((struct sockaddr_in
*)&r
->arp_netmask
)->sin_addr
.s_addr
;
1000 if (mask
&& mask
!= htonl(0xFFFFFFFF))
1002 if (!dev
&& (r
->arp_flags
& ATF_COM
)) {
1003 dev
= dev_getbyhwaddr_rcu(net
, r
->arp_ha
.sa_family
,
1009 if (pneigh_lookup(&arp_tbl
, net
, &ip
, dev
, 1) == NULL
)
1014 return arp_req_set_proxy(net
, dev
, 1);
1017 static int arp_req_set(struct net
*net
, struct arpreq
*r
,
1018 struct net_device
*dev
)
1021 struct neighbour
*neigh
;
1024 if (r
->arp_flags
& ATF_PUBL
)
1025 return arp_req_set_public(net
, r
, dev
);
1027 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
1028 if (r
->arp_flags
& ATF_PERM
)
1029 r
->arp_flags
|= ATF_COM
;
1031 struct rtable
*rt
= ip_route_output(net
, ip
, 0, RTO_ONLINK
, 0);
1040 switch (dev
->type
) {
1041 #if IS_ENABLED(CONFIG_FDDI)
1044 * According to RFC 1390, FDDI devices should accept ARP
1045 * hardware types of 1 (Ethernet). However, to be more
1046 * robust, we'll accept hardware types of either 1 (Ethernet)
1047 * or 6 (IEEE 802.2).
1049 if (r
->arp_ha
.sa_family
!= ARPHRD_FDDI
&&
1050 r
->arp_ha
.sa_family
!= ARPHRD_ETHER
&&
1051 r
->arp_ha
.sa_family
!= ARPHRD_IEEE802
)
1056 if (r
->arp_ha
.sa_family
!= dev
->type
)
1061 neigh
= __neigh_lookup_errno(&arp_tbl
, &ip
, dev
);
1062 err
= PTR_ERR(neigh
);
1063 if (!IS_ERR(neigh
)) {
1064 unsigned int state
= NUD_STALE
;
1065 if (r
->arp_flags
& ATF_PERM
)
1066 state
= NUD_PERMANENT
;
1067 err
= neigh_update(neigh
, (r
->arp_flags
& ATF_COM
) ?
1068 r
->arp_ha
.sa_data
: NULL
, state
,
1069 NEIGH_UPDATE_F_OVERRIDE
|
1070 NEIGH_UPDATE_F_ADMIN
);
1071 neigh_release(neigh
);
1076 static unsigned int arp_state_to_flags(struct neighbour
*neigh
)
1078 if (neigh
->nud_state
&NUD_PERMANENT
)
1079 return ATF_PERM
| ATF_COM
;
1080 else if (neigh
->nud_state
&NUD_VALID
)
1087 * Get an ARP cache entry.
1090 static int arp_req_get(struct arpreq
*r
, struct net_device
*dev
)
1092 __be32 ip
= ((struct sockaddr_in
*) &r
->arp_pa
)->sin_addr
.s_addr
;
1093 struct neighbour
*neigh
;
1096 neigh
= neigh_lookup(&arp_tbl
, &ip
, dev
);
1098 read_lock_bh(&neigh
->lock
);
1099 memcpy(r
->arp_ha
.sa_data
, neigh
->ha
, dev
->addr_len
);
1100 r
->arp_flags
= arp_state_to_flags(neigh
);
1101 read_unlock_bh(&neigh
->lock
);
1102 r
->arp_ha
.sa_family
= dev
->type
;
1103 strlcpy(r
->arp_dev
, dev
->name
, sizeof(r
->arp_dev
));
1104 neigh_release(neigh
);
1110 int arp_invalidate(struct net_device
*dev
, __be32 ip
)
1112 struct neighbour
*neigh
= neigh_lookup(&arp_tbl
, &ip
, dev
);
1116 if (neigh
->nud_state
& ~NUD_NOARP
)
1117 err
= neigh_update(neigh
, NULL
, NUD_FAILED
,
1118 NEIGH_UPDATE_F_OVERRIDE
|
1119 NEIGH_UPDATE_F_ADMIN
);
1120 neigh_release(neigh
);
1125 EXPORT_SYMBOL(arp_invalidate
);
1127 static int arp_req_delete_public(struct net
*net
, struct arpreq
*r
,
1128 struct net_device
*dev
)
1130 __be32 ip
= ((struct sockaddr_in
*) &r
->arp_pa
)->sin_addr
.s_addr
;
1131 __be32 mask
= ((struct sockaddr_in
*)&r
->arp_netmask
)->sin_addr
.s_addr
;
1133 if (mask
== htonl(0xFFFFFFFF))
1134 return pneigh_delete(&arp_tbl
, net
, &ip
, dev
);
1139 return arp_req_set_proxy(net
, dev
, 0);
1142 static int arp_req_delete(struct net
*net
, struct arpreq
*r
,
1143 struct net_device
*dev
)
1147 if (r
->arp_flags
& ATF_PUBL
)
1148 return arp_req_delete_public(net
, r
, dev
);
1150 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
1152 struct rtable
*rt
= ip_route_output(net
, ip
, 0, RTO_ONLINK
, 0);
1160 return arp_invalidate(dev
, ip
);
1164 * Handle an ARP layer I/O control request.
1167 int arp_ioctl(struct net
*net
, unsigned int cmd
, void __user
*arg
)
1171 struct net_device
*dev
= NULL
;
1176 if (!ns_capable(net
->user_ns
, CAP_NET_ADMIN
))
1179 err
= copy_from_user(&r
, arg
, sizeof(struct arpreq
));
1187 if (r
.arp_pa
.sa_family
!= AF_INET
)
1188 return -EPFNOSUPPORT
;
1190 if (!(r
.arp_flags
& ATF_PUBL
) &&
1191 (r
.arp_flags
& (ATF_NETMASK
| ATF_DONTPUB
)))
1193 if (!(r
.arp_flags
& ATF_NETMASK
))
1194 ((struct sockaddr_in
*)&r
.arp_netmask
)->sin_addr
.s_addr
=
1195 htonl(0xFFFFFFFFUL
);
1199 dev
= __dev_get_by_name(net
, r
.arp_dev
);
1203 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1204 if (!r
.arp_ha
.sa_family
)
1205 r
.arp_ha
.sa_family
= dev
->type
;
1207 if ((r
.arp_flags
& ATF_COM
) && r
.arp_ha
.sa_family
!= dev
->type
)
1209 } else if (cmd
== SIOCGARP
) {
1216 err
= arp_req_delete(net
, &r
, dev
);
1219 err
= arp_req_set(net
, &r
, dev
);
1222 err
= arp_req_get(&r
, dev
);
1227 if (cmd
== SIOCGARP
&& !err
&& copy_to_user(arg
, &r
, sizeof(r
)))
1232 static int arp_netdev_event(struct notifier_block
*this, unsigned long event
,
1235 struct net_device
*dev
= netdev_notifier_info_to_dev(ptr
);
1236 struct netdev_notifier_change_info
*change_info
;
1239 case NETDEV_CHANGEADDR
:
1240 neigh_changeaddr(&arp_tbl
, dev
);
1241 rt_cache_flush(dev_net(dev
));
1245 if (change_info
->flags_changed
& IFF_NOARP
)
1246 neigh_changeaddr(&arp_tbl
, dev
);
1255 static struct notifier_block arp_netdev_notifier
= {
1256 .notifier_call
= arp_netdev_event
,
1259 /* Note, that it is not on notifier chain.
1260 It is necessary, that this routine was called after route cache will be
1263 void arp_ifdown(struct net_device
*dev
)
1265 neigh_ifdown(&arp_tbl
, dev
);
1270 * Called once on startup.
1273 static struct packet_type arp_packet_type __read_mostly
= {
1274 .type
= cpu_to_be16(ETH_P_ARP
),
1278 static int arp_proc_init(void);
1280 void __init
arp_init(void)
1282 neigh_table_init(&arp_tbl
);
1284 dev_add_pack(&arp_packet_type
);
1286 #ifdef CONFIG_SYSCTL
1287 neigh_sysctl_register(NULL
, &arp_tbl
.parms
, "ipv4", NULL
);
1289 register_netdevice_notifier(&arp_netdev_notifier
);
1292 #ifdef CONFIG_PROC_FS
1293 #if IS_ENABLED(CONFIG_AX25)
1295 /* ------------------------------------------------------------------------ */
1297 * ax25 -> ASCII conversion
1299 static char *ax2asc2(ax25_address
*a
, char *buf
)
1304 for (n
= 0, s
= buf
; n
< 6; n
++) {
1305 c
= (a
->ax25_call
[n
] >> 1) & 0x7F;
1312 n
= (a
->ax25_call
[6] >> 1) & 0x0F;
1321 if (*buf
== '\0' || *buf
== '-')
1326 #endif /* CONFIG_AX25 */
1328 #define HBUFFERLEN 30
1330 static void arp_format_neigh_entry(struct seq_file
*seq
,
1331 struct neighbour
*n
)
1333 char hbuffer
[HBUFFERLEN
];
1336 struct net_device
*dev
= n
->dev
;
1337 int hatype
= dev
->type
;
1339 read_lock(&n
->lock
);
1340 /* Convert hardware address to XX:XX:XX:XX ... form. */
1341 #if IS_ENABLED(CONFIG_AX25)
1342 if (hatype
== ARPHRD_AX25
|| hatype
== ARPHRD_NETROM
)
1343 ax2asc2((ax25_address
*)n
->ha
, hbuffer
);
1346 for (k
= 0, j
= 0; k
< HBUFFERLEN
- 3 && j
< dev
->addr_len
; j
++) {
1347 hbuffer
[k
++] = hex_asc_hi(n
->ha
[j
]);
1348 hbuffer
[k
++] = hex_asc_lo(n
->ha
[j
]);
1354 #if IS_ENABLED(CONFIG_AX25)
1357 sprintf(tbuf
, "%pI4", n
->primary_key
);
1358 seq_printf(seq
, "%-16s 0x%-10x0x%-10x%s * %s\n",
1359 tbuf
, hatype
, arp_state_to_flags(n
), hbuffer
, dev
->name
);
1360 read_unlock(&n
->lock
);
1363 static void arp_format_pneigh_entry(struct seq_file
*seq
,
1364 struct pneigh_entry
*n
)
1366 struct net_device
*dev
= n
->dev
;
1367 int hatype
= dev
? dev
->type
: 0;
1370 sprintf(tbuf
, "%pI4", n
->key
);
1371 seq_printf(seq
, "%-16s 0x%-10x0x%-10x%s * %s\n",
1372 tbuf
, hatype
, ATF_PUBL
| ATF_PERM
, "00:00:00:00:00:00",
1373 dev
? dev
->name
: "*");
1376 static int arp_seq_show(struct seq_file
*seq
, void *v
)
1378 if (v
== SEQ_START_TOKEN
) {
1379 seq_puts(seq
, "IP address HW type Flags "
1380 "HW address Mask Device\n");
1382 struct neigh_seq_state
*state
= seq
->private;
1384 if (state
->flags
& NEIGH_SEQ_IS_PNEIGH
)
1385 arp_format_pneigh_entry(seq
, v
);
1387 arp_format_neigh_entry(seq
, v
);
1393 static void *arp_seq_start(struct seq_file
*seq
, loff_t
*pos
)
1395 /* Don't want to confuse "arp -a" w/ magic entries,
1396 * so we tell the generic iterator to skip NUD_NOARP.
1398 return neigh_seq_start(seq
, pos
, &arp_tbl
, NEIGH_SEQ_SKIP_NOARP
);
1401 /* ------------------------------------------------------------------------ */
1403 static const struct seq_operations arp_seq_ops
= {
1404 .start
= arp_seq_start
,
1405 .next
= neigh_seq_next
,
1406 .stop
= neigh_seq_stop
,
1407 .show
= arp_seq_show
,
1410 static int arp_seq_open(struct inode
*inode
, struct file
*file
)
1412 return seq_open_net(inode
, file
, &arp_seq_ops
,
1413 sizeof(struct neigh_seq_state
));
1416 static const struct file_operations arp_seq_fops
= {
1417 .owner
= THIS_MODULE
,
1418 .open
= arp_seq_open
,
1420 .llseek
= seq_lseek
,
1421 .release
= seq_release_net
,
1425 static int __net_init
arp_net_init(struct net
*net
)
1427 if (!proc_create("arp", S_IRUGO
, net
->proc_net
, &arp_seq_fops
))
1432 static void __net_exit
arp_net_exit(struct net
*net
)
1434 remove_proc_entry("arp", net
->proc_net
);
1437 static struct pernet_operations arp_net_ops
= {
1438 .init
= arp_net_init
,
1439 .exit
= arp_net_exit
,
1442 static int __init
arp_proc_init(void)
1444 return register_pernet_subsys(&arp_net_ops
);
1447 #else /* CONFIG_PROC_FS */
1449 static int __init
arp_proc_init(void)
1454 #endif /* CONFIG_PROC_FS */