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/jhash.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>
116 #if defined(CONFIG_ATM_CLIP) || defined(CONFIG_ATM_CLIP_MODULE)
117 #include <net/atmclip.h>
118 struct neigh_table
*clip_tbl_hook
;
119 EXPORT_SYMBOL(clip_tbl_hook
);
122 #include <asm/system.h>
123 #include <linux/uaccess.h>
125 #include <linux/netfilter_arp.h>
128 * Interface to generic neighbour cache.
130 static u32
arp_hash(const void *pkey
, const struct net_device
*dev
);
131 static int arp_constructor(struct neighbour
*neigh
);
132 static void arp_solicit(struct neighbour
*neigh
, struct sk_buff
*skb
);
133 static void arp_error_report(struct neighbour
*neigh
, struct sk_buff
*skb
);
134 static void parp_redo(struct sk_buff
*skb
);
136 static const struct neigh_ops arp_generic_ops
= {
138 .solicit
= arp_solicit
,
139 .error_report
= arp_error_report
,
140 .output
= neigh_resolve_output
,
141 .connected_output
= neigh_connected_output
,
142 .hh_output
= dev_queue_xmit
,
143 .queue_xmit
= dev_queue_xmit
,
146 static const struct neigh_ops arp_hh_ops
= {
148 .solicit
= arp_solicit
,
149 .error_report
= arp_error_report
,
150 .output
= neigh_resolve_output
,
151 .connected_output
= neigh_resolve_output
,
152 .hh_output
= dev_queue_xmit
,
153 .queue_xmit
= dev_queue_xmit
,
156 static const struct neigh_ops arp_direct_ops
= {
158 .output
= dev_queue_xmit
,
159 .connected_output
= dev_queue_xmit
,
160 .hh_output
= dev_queue_xmit
,
161 .queue_xmit
= dev_queue_xmit
,
164 const struct neigh_ops arp_broken_ops
= {
166 .solicit
= arp_solicit
,
167 .error_report
= arp_error_report
,
168 .output
= neigh_compat_output
,
169 .connected_output
= neigh_compat_output
,
170 .hh_output
= dev_queue_xmit
,
171 .queue_xmit
= dev_queue_xmit
,
173 EXPORT_SYMBOL(arp_broken_ops
);
175 struct neigh_table arp_tbl
= {
177 .entry_size
= sizeof(struct neighbour
) + 4,
180 .constructor
= arp_constructor
,
181 .proxy_redo
= parp_redo
,
185 .base_reachable_time
= 30 * HZ
,
186 .retrans_time
= 1 * HZ
,
187 .gc_staletime
= 60 * HZ
,
188 .reachable_time
= 30 * HZ
,
189 .delay_probe_time
= 5 * HZ
,
193 .anycast_delay
= 1 * HZ
,
194 .proxy_delay
= (8 * HZ
) / 10,
198 .gc_interval
= 30 * HZ
,
203 EXPORT_SYMBOL(arp_tbl
);
205 int arp_mc_map(__be32 addr
, u8
*haddr
, struct net_device
*dev
, int dir
)
211 ip_eth_mc_map(addr
, haddr
);
213 case ARPHRD_IEEE802_TR
:
214 ip_tr_mc_map(addr
, haddr
);
216 case ARPHRD_INFINIBAND
:
217 ip_ib_mc_map(addr
, dev
->broadcast
, haddr
);
221 memcpy(haddr
, dev
->broadcast
, dev
->addr_len
);
229 static u32
arp_hash(const void *pkey
, const struct net_device
*dev
)
231 return jhash_2words(*(u32
*)pkey
, dev
->ifindex
, arp_tbl
.hash_rnd
);
234 static int arp_constructor(struct neighbour
*neigh
)
236 __be32 addr
= *(__be32
*)neigh
->primary_key
;
237 struct net_device
*dev
= neigh
->dev
;
238 struct in_device
*in_dev
;
239 struct neigh_parms
*parms
;
242 in_dev
= __in_dev_get_rcu(dev
);
243 if (in_dev
== NULL
) {
248 neigh
->type
= inet_addr_type(dev_net(dev
), addr
);
250 parms
= in_dev
->arp_parms
;
251 __neigh_parms_put(neigh
->parms
);
252 neigh
->parms
= neigh_parms_clone(parms
);
255 if (!dev
->header_ops
) {
256 neigh
->nud_state
= NUD_NOARP
;
257 neigh
->ops
= &arp_direct_ops
;
258 neigh
->output
= neigh
->ops
->queue_xmit
;
260 /* Good devices (checked by reading texts, but only Ethernet is
263 ARPHRD_ETHER: (ethernet, apfddi)
266 ARPHRD_METRICOM: (strip)
270 ARPHRD_IPDDP will also work, if author repairs it.
271 I did not it, because this driver does not work even
276 /* So... these "amateur" devices are hopeless.
277 The only thing, that I can say now:
278 It is very sad that we need to keep ugly obsolete
279 code to make them happy.
281 They should be moved to more reasonable state, now
282 they use rebuild_header INSTEAD OF hard_start_xmit!!!
283 Besides that, they are sort of out of date
284 (a lot of redundant clones/copies, useless in 2.1),
285 I wonder why people believe that they work.
291 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
293 #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
296 neigh
->ops
= &arp_broken_ops
;
297 neigh
->output
= neigh
->ops
->output
;
304 if (neigh
->type
== RTN_MULTICAST
) {
305 neigh
->nud_state
= NUD_NOARP
;
306 arp_mc_map(addr
, neigh
->ha
, dev
, 1);
307 } else if (dev
->flags
& (IFF_NOARP
| IFF_LOOPBACK
)) {
308 neigh
->nud_state
= NUD_NOARP
;
309 memcpy(neigh
->ha
, dev
->dev_addr
, dev
->addr_len
);
310 } else if (neigh
->type
== RTN_BROADCAST
||
311 (dev
->flags
& IFF_POINTOPOINT
)) {
312 neigh
->nud_state
= NUD_NOARP
;
313 memcpy(neigh
->ha
, dev
->broadcast
, dev
->addr_len
);
316 if (dev
->header_ops
->cache
)
317 neigh
->ops
= &arp_hh_ops
;
319 neigh
->ops
= &arp_generic_ops
;
321 if (neigh
->nud_state
& NUD_VALID
)
322 neigh
->output
= neigh
->ops
->connected_output
;
324 neigh
->output
= neigh
->ops
->output
;
329 static void arp_error_report(struct neighbour
*neigh
, struct sk_buff
*skb
)
331 dst_link_failure(skb
);
335 static void arp_solicit(struct neighbour
*neigh
, struct sk_buff
*skb
)
339 struct net_device
*dev
= neigh
->dev
;
340 __be32 target
= *(__be32
*)neigh
->primary_key
;
341 int probes
= atomic_read(&neigh
->probes
);
342 struct in_device
*in_dev
;
345 in_dev
= __in_dev_get_rcu(dev
);
350 switch (IN_DEV_ARP_ANNOUNCE(in_dev
)) {
352 case 0: /* By default announce any local IP */
353 if (skb
&& inet_addr_type(dev_net(dev
),
354 ip_hdr(skb
)->saddr
) == RTN_LOCAL
)
355 saddr
= ip_hdr(skb
)->saddr
;
357 case 1: /* Restrict announcements of saddr in same subnet */
360 saddr
= ip_hdr(skb
)->saddr
;
361 if (inet_addr_type(dev_net(dev
), saddr
) == RTN_LOCAL
) {
362 /* saddr should be known to target */
363 if (inet_addr_onlink(in_dev
, target
, saddr
))
368 case 2: /* Avoid secondary IPs, get a primary/preferred one */
374 saddr
= inet_select_addr(dev
, target
, RT_SCOPE_LINK
);
376 probes
-= neigh
->parms
->ucast_probes
;
378 if (!(neigh
->nud_state
& NUD_VALID
))
380 "trying to ucast probe in NUD_INVALID\n");
382 read_lock_bh(&neigh
->lock
);
384 probes
-= neigh
->parms
->app_probes
;
393 arp_send(ARPOP_REQUEST
, ETH_P_ARP
, target
, dev
, saddr
,
394 dst_ha
, dev
->dev_addr
, NULL
);
396 read_unlock_bh(&neigh
->lock
);
399 static int arp_ignore(struct in_device
*in_dev
, __be32 sip
, __be32 tip
)
403 switch (IN_DEV_ARP_IGNORE(in_dev
)) {
404 case 0: /* Reply, the tip is already validated */
406 case 1: /* Reply only if tip is configured on the incoming interface */
408 scope
= RT_SCOPE_HOST
;
411 * Reply only if tip is configured on the incoming interface
412 * and is in same subnet as sip
414 scope
= RT_SCOPE_HOST
;
416 case 3: /* Do not reply for scope host addresses */
418 scope
= RT_SCOPE_LINK
;
420 case 4: /* Reserved */
425 case 8: /* Do not reply */
430 return !inet_confirm_addr(in_dev
, sip
, tip
, scope
);
433 static int arp_filter(__be32 sip
, __be32 tip
, struct net_device
*dev
)
435 struct flowi fl
= { .nl_u
= { .ip4_u
= { .daddr
= sip
,
439 /*unsigned long now; */
440 struct net
*net
= dev_net(dev
);
442 if (ip_route_output_key(net
, &rt
, &fl
) < 0)
444 if (rt
->dst
.dev
!= dev
) {
445 NET_INC_STATS_BH(net
, LINUX_MIB_ARPFILTER
);
452 /* OBSOLETE FUNCTIONS */
455 * Find an arp mapping in the cache. If not found, post a request.
457 * It is very UGLY routine: it DOES NOT use skb->dst->neighbour,
458 * even if it exists. It is supposed that skb->dev was mangled
459 * by a virtual device (eql, shaper). Nobody but broken devices
460 * is allowed to use this function, it is scheduled to be removed. --ANK
463 static int arp_set_predefined(int addr_hint
, unsigned char *haddr
,
464 __be32 paddr
, struct net_device
*dev
)
468 printk(KERN_DEBUG
"ARP: arp called for own IP address\n");
469 memcpy(haddr
, dev
->dev_addr
, dev
->addr_len
);
472 arp_mc_map(paddr
, haddr
, dev
, 1);
475 memcpy(haddr
, dev
->broadcast
, dev
->addr_len
);
482 int arp_find(unsigned char *haddr
, struct sk_buff
*skb
)
484 struct net_device
*dev
= skb
->dev
;
489 printk(KERN_DEBUG
"arp_find is called with dst==NULL\n");
494 paddr
= skb_rtable(skb
)->rt_gateway
;
496 if (arp_set_predefined(inet_addr_type(dev_net(dev
), paddr
), haddr
,
500 n
= __neigh_lookup(&arp_tbl
, &paddr
, dev
, 1);
504 if (n
->nud_state
&NUD_VALID
|| neigh_event_send(n
, skb
) == 0) {
505 read_lock_bh(&n
->lock
);
506 memcpy(haddr
, n
->ha
, dev
->addr_len
);
507 read_unlock_bh(&n
->lock
);
516 EXPORT_SYMBOL(arp_find
);
518 /* END OF OBSOLETE FUNCTIONS */
520 int arp_bind_neighbour(struct dst_entry
*dst
)
522 struct net_device
*dev
= dst
->dev
;
523 struct neighbour
*n
= dst
->neighbour
;
528 __be32 nexthop
= ((struct rtable
*)dst
)->rt_gateway
;
529 if (dev
->flags
& (IFF_LOOPBACK
| IFF_POINTOPOINT
))
531 n
= __neigh_lookup_errno(
532 #if defined(CONFIG_ATM_CLIP) || defined(CONFIG_ATM_CLIP_MODULE)
533 dev
->type
== ARPHRD_ATM
?
536 &arp_tbl
, &nexthop
, dev
);
545 * Check if we can use proxy ARP for this path
547 static inline int arp_fwd_proxy(struct in_device
*in_dev
,
548 struct net_device
*dev
, struct rtable
*rt
)
550 struct in_device
*out_dev
;
553 if (rt
->dst
.dev
== dev
)
556 if (!IN_DEV_PROXY_ARP(in_dev
))
558 imi
= IN_DEV_MEDIUM_ID(in_dev
);
564 /* place to check for proxy_arp for routes */
566 out_dev
= __in_dev_get_rcu(rt
->dst
.dev
);
568 omi
= IN_DEV_MEDIUM_ID(out_dev
);
570 return (omi
!= imi
&& omi
!= -1);
574 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
576 * RFC3069 supports proxy arp replies back to the same interface. This
577 * is done to support (ethernet) switch features, like RFC 3069, where
578 * the individual ports are not allowed to communicate with each
579 * other, BUT they are allowed to talk to the upstream router. As
580 * described in RFC 3069, it is possible to allow these hosts to
581 * communicate through the upstream router, by proxy_arp'ing.
583 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
585 * This technology is known by different names:
586 * In RFC 3069 it is called VLAN Aggregation.
587 * Cisco and Allied Telesyn call it Private VLAN.
588 * Hewlett-Packard call it Source-Port filtering or port-isolation.
589 * Ericsson call it MAC-Forced Forwarding (RFC Draft).
592 static inline int arp_fwd_pvlan(struct in_device
*in_dev
,
593 struct net_device
*dev
, struct rtable
*rt
,
594 __be32 sip
, __be32 tip
)
596 /* Private VLAN is only concerned about the same ethernet segment */
597 if (rt
->dst
.dev
!= dev
)
600 /* Don't reply on self probes (often done by windowz boxes)*/
604 if (IN_DEV_PROXY_ARP_PVLAN(in_dev
))
611 * Interface to link layer: send routine and receive handler.
615 * Create an arp packet. If (dest_hw == NULL), we create a broadcast
618 struct sk_buff
*arp_create(int type
, int ptype
, __be32 dest_ip
,
619 struct net_device
*dev
, __be32 src_ip
,
620 const unsigned char *dest_hw
,
621 const unsigned char *src_hw
,
622 const unsigned char *target_hw
)
626 unsigned char *arp_ptr
;
632 skb
= alloc_skb(arp_hdr_len(dev
) + LL_ALLOCATED_SPACE(dev
), GFP_ATOMIC
);
636 skb_reserve(skb
, LL_RESERVED_SPACE(dev
));
637 skb_reset_network_header(skb
);
638 arp
= (struct arphdr
*) skb_put(skb
, arp_hdr_len(dev
));
640 skb
->protocol
= htons(ETH_P_ARP
);
642 src_hw
= dev
->dev_addr
;
644 dest_hw
= dev
->broadcast
;
647 * Fill the device header for the ARP frame
649 if (dev_hard_header(skb
, dev
, ptype
, dest_hw
, src_hw
, skb
->len
) < 0)
653 * Fill out the arp protocol part.
655 * The arp hardware type should match the device type, except for FDDI,
656 * which (according to RFC 1390) should always equal 1 (Ethernet).
659 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
660 * DIX code for the protocol. Make these device structure fields.
664 arp
->ar_hrd
= htons(dev
->type
);
665 arp
->ar_pro
= htons(ETH_P_IP
);
668 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
670 arp
->ar_hrd
= htons(ARPHRD_AX25
);
671 arp
->ar_pro
= htons(AX25_P_IP
);
674 #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
676 arp
->ar_hrd
= htons(ARPHRD_NETROM
);
677 arp
->ar_pro
= htons(AX25_P_IP
);
682 #if defined(CONFIG_FDDI) || defined(CONFIG_FDDI_MODULE)
684 arp
->ar_hrd
= htons(ARPHRD_ETHER
);
685 arp
->ar_pro
= htons(ETH_P_IP
);
688 #if defined(CONFIG_TR) || defined(CONFIG_TR_MODULE)
689 case ARPHRD_IEEE802_TR
:
690 arp
->ar_hrd
= htons(ARPHRD_IEEE802
);
691 arp
->ar_pro
= htons(ETH_P_IP
);
696 arp
->ar_hln
= dev
->addr_len
;
698 arp
->ar_op
= htons(type
);
700 arp_ptr
= (unsigned char *)(arp
+ 1);
702 memcpy(arp_ptr
, src_hw
, dev
->addr_len
);
703 arp_ptr
+= dev
->addr_len
;
704 memcpy(arp_ptr
, &src_ip
, 4);
706 if (target_hw
!= NULL
)
707 memcpy(arp_ptr
, target_hw
, dev
->addr_len
);
709 memset(arp_ptr
, 0, dev
->addr_len
);
710 arp_ptr
+= dev
->addr_len
;
711 memcpy(arp_ptr
, &dest_ip
, 4);
719 EXPORT_SYMBOL(arp_create
);
722 * Send an arp packet.
724 void arp_xmit(struct sk_buff
*skb
)
726 /* Send it off, maybe filter it using firewalling first. */
727 NF_HOOK(NFPROTO_ARP
, NF_ARP_OUT
, skb
, NULL
, skb
->dev
, dev_queue_xmit
);
729 EXPORT_SYMBOL(arp_xmit
);
732 * Create and send an arp packet.
734 void arp_send(int type
, int ptype
, __be32 dest_ip
,
735 struct net_device
*dev
, __be32 src_ip
,
736 const unsigned char *dest_hw
, const unsigned char *src_hw
,
737 const unsigned char *target_hw
)
742 * No arp on this interface.
745 if (dev
->flags
&IFF_NOARP
)
748 skb
= arp_create(type
, ptype
, dest_ip
, dev
, src_ip
,
749 dest_hw
, src_hw
, target_hw
);
755 EXPORT_SYMBOL(arp_send
);
758 * Process an arp request.
761 static int arp_process(struct sk_buff
*skb
)
763 struct net_device
*dev
= skb
->dev
;
764 struct in_device
*in_dev
= __in_dev_get_rcu(dev
);
766 unsigned char *arp_ptr
;
770 u16 dev_type
= dev
->type
;
773 struct net
*net
= dev_net(dev
);
775 /* arp_rcv below verifies the ARP header and verifies the device
786 if (arp
->ar_pro
!= htons(ETH_P_IP
) ||
787 htons(dev_type
) != arp
->ar_hrd
)
791 case ARPHRD_IEEE802_TR
:
795 * ETHERNET, Token Ring and Fibre Channel (which are IEEE 802
796 * devices, according to RFC 2625) devices will accept ARP
797 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
798 * This is the case also of FDDI, where the RFC 1390 says that
799 * FDDI devices should accept ARP hardware of (1) Ethernet,
800 * however, to be more robust, we'll accept both 1 (Ethernet)
803 if ((arp
->ar_hrd
!= htons(ARPHRD_ETHER
) &&
804 arp
->ar_hrd
!= htons(ARPHRD_IEEE802
)) ||
805 arp
->ar_pro
!= htons(ETH_P_IP
))
809 if (arp
->ar_pro
!= htons(AX25_P_IP
) ||
810 arp
->ar_hrd
!= htons(ARPHRD_AX25
))
814 if (arp
->ar_pro
!= htons(AX25_P_IP
) ||
815 arp
->ar_hrd
!= htons(ARPHRD_NETROM
))
820 /* Understand only these message types */
822 if (arp
->ar_op
!= htons(ARPOP_REPLY
) &&
823 arp
->ar_op
!= htons(ARPOP_REQUEST
))
829 arp_ptr
= (unsigned char *)(arp
+ 1);
831 arp_ptr
+= dev
->addr_len
;
832 memcpy(&sip
, arp_ptr
, 4);
834 arp_ptr
+= dev
->addr_len
;
835 memcpy(&tip
, arp_ptr
, 4);
837 * Check for bad requests for 127.x.x.x and requests for multicast
838 * addresses. If this is one such, delete it.
840 if (ipv4_is_loopback(tip
) || ipv4_is_multicast(tip
))
844 * Special case: We must set Frame Relay source Q.922 address
846 if (dev_type
== ARPHRD_DLCI
)
847 sha
= dev
->broadcast
;
850 * Process entry. The idea here is we want to send a reply if it is a
851 * request for us or if it is a request for someone else that we hold
852 * a proxy for. We want to add an entry to our cache if it is a reply
853 * to us or if it is a request for our address.
854 * (The assumption for this last is that if someone is requesting our
855 * address, they are probably intending to talk to us, so it saves time
856 * if we cache their address. Their address is also probably not in
857 * our cache, since ours is not in their cache.)
859 * Putting this another way, we only care about replies if they are to
860 * us, in which case we add them to the cache. For requests, we care
861 * about those for us and those for our proxies. We reply to both,
862 * and in the case of requests for us we add the requester to the arp
866 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
868 if (arp
->ar_op
== htons(ARPOP_REQUEST
) &&
869 inet_addr_type(net
, tip
) == RTN_LOCAL
&&
870 !arp_ignore(in_dev
, sip
, tip
))
871 arp_send(ARPOP_REPLY
, ETH_P_ARP
, sip
, dev
, tip
, sha
,
876 if (arp
->ar_op
== htons(ARPOP_REQUEST
) &&
877 ip_route_input_noref(skb
, tip
, sip
, 0, dev
) == 0) {
879 rt
= skb_rtable(skb
);
880 addr_type
= rt
->rt_type
;
882 if (addr_type
== RTN_LOCAL
) {
885 dont_send
= arp_ignore(in_dev
, sip
, tip
);
886 if (!dont_send
&& IN_DEV_ARPFILTER(in_dev
))
887 dont_send
|= arp_filter(sip
, tip
, dev
);
889 n
= neigh_event_ns(&arp_tbl
, sha
, &sip
, dev
);
891 arp_send(ARPOP_REPLY
, ETH_P_ARP
, sip
,
892 dev
, tip
, sha
, dev
->dev_addr
,
898 } else if (IN_DEV_FORWARD(in_dev
)) {
899 if (addr_type
== RTN_UNICAST
&&
900 (arp_fwd_proxy(in_dev
, dev
, rt
) ||
901 arp_fwd_pvlan(in_dev
, dev
, rt
, sip
, tip
) ||
902 pneigh_lookup(&arp_tbl
, net
, &tip
, dev
, 0))) {
903 n
= neigh_event_ns(&arp_tbl
, sha
, &sip
, dev
);
907 if (NEIGH_CB(skb
)->flags
& LOCALLY_ENQUEUED
||
908 skb
->pkt_type
== PACKET_HOST
||
909 in_dev
->arp_parms
->proxy_delay
== 0) {
910 arp_send(ARPOP_REPLY
, ETH_P_ARP
, sip
,
911 dev
, tip
, sha
, dev
->dev_addr
,
914 pneigh_enqueue(&arp_tbl
,
915 in_dev
->arp_parms
, skb
);
923 /* Update our ARP tables */
925 n
= __neigh_lookup(&arp_tbl
, &sip
, dev
, 0);
927 if (IPV4_DEVCONF_ALL(dev_net(dev
), ARP_ACCEPT
)) {
928 /* Unsolicited ARP is not accepted by default.
929 It is possible, that this option should be enabled for some
930 devices (strip is candidate)
933 (arp
->ar_op
== htons(ARPOP_REPLY
) ||
934 (arp
->ar_op
== htons(ARPOP_REQUEST
) && tip
== sip
)) &&
935 inet_addr_type(net
, sip
) == RTN_UNICAST
)
936 n
= __neigh_lookup(&arp_tbl
, &sip
, dev
, 1);
940 int state
= NUD_REACHABLE
;
943 /* If several different ARP replies follows back-to-back,
944 use the FIRST one. It is possible, if several proxy
945 agents are active. Taking the first reply prevents
946 arp trashing and chooses the fastest router.
948 override
= time_after(jiffies
, n
->updated
+ n
->parms
->locktime
);
950 /* Broadcast replies and request packets
951 do not assert neighbour reachability.
953 if (arp
->ar_op
!= htons(ARPOP_REPLY
) ||
954 skb
->pkt_type
!= PACKET_HOST
)
956 neigh_update(n
, sha
, state
,
957 override
? NEIGH_UPDATE_F_OVERRIDE
: 0);
966 static void parp_redo(struct sk_buff
*skb
)
973 * Receive an arp request from the device layer.
976 static int arp_rcv(struct sk_buff
*skb
, struct net_device
*dev
,
977 struct packet_type
*pt
, struct net_device
*orig_dev
)
981 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
982 if (!pskb_may_pull(skb
, arp_hdr_len(dev
)))
986 if (arp
->ar_hln
!= dev
->addr_len
||
987 dev
->flags
& IFF_NOARP
||
988 skb
->pkt_type
== PACKET_OTHERHOST
||
989 skb
->pkt_type
== PACKET_LOOPBACK
||
993 skb
= skb_share_check(skb
, GFP_ATOMIC
);
997 memset(NEIGH_CB(skb
), 0, sizeof(struct neighbour_cb
));
999 return NF_HOOK(NFPROTO_ARP
, NF_ARP_IN
, skb
, dev
, NULL
, arp_process
);
1008 * User level interface (ioctl)
1012 * Set (create) an ARP cache entry.
1015 static int arp_req_set_proxy(struct net
*net
, struct net_device
*dev
, int on
)
1018 IPV4_DEVCONF_ALL(net
, PROXY_ARP
) = on
;
1021 if (__in_dev_get_rtnl(dev
)) {
1022 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev
), PROXY_ARP
, on
);
1028 static int arp_req_set_public(struct net
*net
, struct arpreq
*r
,
1029 struct net_device
*dev
)
1031 __be32 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
1032 __be32 mask
= ((struct sockaddr_in
*)&r
->arp_netmask
)->sin_addr
.s_addr
;
1034 if (mask
&& mask
!= htonl(0xFFFFFFFF))
1036 if (!dev
&& (r
->arp_flags
& ATF_COM
)) {
1037 dev
= dev_getbyhwaddr(net
, r
->arp_ha
.sa_family
,
1043 if (pneigh_lookup(&arp_tbl
, net
, &ip
, dev
, 1) == NULL
)
1048 return arp_req_set_proxy(net
, dev
, 1);
1051 static int arp_req_set(struct net
*net
, struct arpreq
*r
,
1052 struct net_device
*dev
)
1055 struct neighbour
*neigh
;
1058 if (r
->arp_flags
& ATF_PUBL
)
1059 return arp_req_set_public(net
, r
, dev
);
1061 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
1062 if (r
->arp_flags
& ATF_PERM
)
1063 r
->arp_flags
|= ATF_COM
;
1065 struct flowi fl
= { .nl_u
.ip4_u
= { .daddr
= ip
,
1066 .tos
= RTO_ONLINK
} };
1068 err
= ip_route_output_key(net
, &rt
, &fl
);
1076 switch (dev
->type
) {
1077 #if defined(CONFIG_FDDI) || defined(CONFIG_FDDI_MODULE)
1080 * According to RFC 1390, FDDI devices should accept ARP
1081 * hardware types of 1 (Ethernet). However, to be more
1082 * robust, we'll accept hardware types of either 1 (Ethernet)
1083 * or 6 (IEEE 802.2).
1085 if (r
->arp_ha
.sa_family
!= ARPHRD_FDDI
&&
1086 r
->arp_ha
.sa_family
!= ARPHRD_ETHER
&&
1087 r
->arp_ha
.sa_family
!= ARPHRD_IEEE802
)
1092 if (r
->arp_ha
.sa_family
!= dev
->type
)
1097 neigh
= __neigh_lookup_errno(&arp_tbl
, &ip
, dev
);
1098 err
= PTR_ERR(neigh
);
1099 if (!IS_ERR(neigh
)) {
1100 unsigned state
= NUD_STALE
;
1101 if (r
->arp_flags
& ATF_PERM
)
1102 state
= NUD_PERMANENT
;
1103 err
= neigh_update(neigh
, (r
->arp_flags
& ATF_COM
) ?
1104 r
->arp_ha
.sa_data
: NULL
, state
,
1105 NEIGH_UPDATE_F_OVERRIDE
|
1106 NEIGH_UPDATE_F_ADMIN
);
1107 neigh_release(neigh
);
1112 static unsigned arp_state_to_flags(struct neighbour
*neigh
)
1114 if (neigh
->nud_state
&NUD_PERMANENT
)
1115 return ATF_PERM
| ATF_COM
;
1116 else if (neigh
->nud_state
&NUD_VALID
)
1123 * Get an ARP cache entry.
1126 static int arp_req_get(struct arpreq
*r
, struct net_device
*dev
)
1128 __be32 ip
= ((struct sockaddr_in
*) &r
->arp_pa
)->sin_addr
.s_addr
;
1129 struct neighbour
*neigh
;
1132 neigh
= neigh_lookup(&arp_tbl
, &ip
, dev
);
1134 read_lock_bh(&neigh
->lock
);
1135 memcpy(r
->arp_ha
.sa_data
, neigh
->ha
, dev
->addr_len
);
1136 r
->arp_flags
= arp_state_to_flags(neigh
);
1137 read_unlock_bh(&neigh
->lock
);
1138 r
->arp_ha
.sa_family
= dev
->type
;
1139 strlcpy(r
->arp_dev
, dev
->name
, sizeof(r
->arp_dev
));
1140 neigh_release(neigh
);
1146 static int arp_req_delete_public(struct net
*net
, struct arpreq
*r
,
1147 struct net_device
*dev
)
1149 __be32 ip
= ((struct sockaddr_in
*) &r
->arp_pa
)->sin_addr
.s_addr
;
1150 __be32 mask
= ((struct sockaddr_in
*)&r
->arp_netmask
)->sin_addr
.s_addr
;
1152 if (mask
== htonl(0xFFFFFFFF))
1153 return pneigh_delete(&arp_tbl
, net
, &ip
, dev
);
1158 return arp_req_set_proxy(net
, dev
, 0);
1161 static int arp_req_delete(struct net
*net
, struct arpreq
*r
,
1162 struct net_device
*dev
)
1166 struct neighbour
*neigh
;
1168 if (r
->arp_flags
& ATF_PUBL
)
1169 return arp_req_delete_public(net
, r
, dev
);
1171 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
1173 struct flowi fl
= { .nl_u
.ip4_u
= { .daddr
= ip
,
1174 .tos
= RTO_ONLINK
} };
1176 err
= ip_route_output_key(net
, &rt
, &fl
);
1185 neigh
= neigh_lookup(&arp_tbl
, &ip
, dev
);
1187 if (neigh
->nud_state
& ~NUD_NOARP
)
1188 err
= neigh_update(neigh
, NULL
, NUD_FAILED
,
1189 NEIGH_UPDATE_F_OVERRIDE
|
1190 NEIGH_UPDATE_F_ADMIN
);
1191 neigh_release(neigh
);
1197 * Handle an ARP layer I/O control request.
1200 int arp_ioctl(struct net
*net
, unsigned int cmd
, void __user
*arg
)
1204 struct net_device
*dev
= NULL
;
1209 if (!capable(CAP_NET_ADMIN
))
1212 err
= copy_from_user(&r
, arg
, sizeof(struct arpreq
));
1220 if (r
.arp_pa
.sa_family
!= AF_INET
)
1221 return -EPFNOSUPPORT
;
1223 if (!(r
.arp_flags
& ATF_PUBL
) &&
1224 (r
.arp_flags
& (ATF_NETMASK
| ATF_DONTPUB
)))
1226 if (!(r
.arp_flags
& ATF_NETMASK
))
1227 ((struct sockaddr_in
*)&r
.arp_netmask
)->sin_addr
.s_addr
=
1228 htonl(0xFFFFFFFFUL
);
1232 dev
= __dev_get_by_name(net
, r
.arp_dev
);
1236 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1237 if (!r
.arp_ha
.sa_family
)
1238 r
.arp_ha
.sa_family
= dev
->type
;
1240 if ((r
.arp_flags
& ATF_COM
) && r
.arp_ha
.sa_family
!= dev
->type
)
1242 } else if (cmd
== SIOCGARP
) {
1249 err
= arp_req_delete(net
, &r
, dev
);
1252 err
= arp_req_set(net
, &r
, dev
);
1255 err
= arp_req_get(&r
, dev
);
1256 if (!err
&& copy_to_user(arg
, &r
, sizeof(r
)))
1265 static int arp_netdev_event(struct notifier_block
*this, unsigned long event
,
1268 struct net_device
*dev
= ptr
;
1271 case NETDEV_CHANGEADDR
:
1272 neigh_changeaddr(&arp_tbl
, dev
);
1273 rt_cache_flush(dev_net(dev
), 0);
1282 static struct notifier_block arp_netdev_notifier
= {
1283 .notifier_call
= arp_netdev_event
,
1286 /* Note, that it is not on notifier chain.
1287 It is necessary, that this routine was called after route cache will be
1290 void arp_ifdown(struct net_device
*dev
)
1292 neigh_ifdown(&arp_tbl
, dev
);
1297 * Called once on startup.
1300 static struct packet_type arp_packet_type __read_mostly
= {
1301 .type
= cpu_to_be16(ETH_P_ARP
),
1305 static int arp_proc_init(void);
1307 void __init
arp_init(void)
1309 neigh_table_init(&arp_tbl
);
1311 dev_add_pack(&arp_packet_type
);
1313 #ifdef CONFIG_SYSCTL
1314 neigh_sysctl_register(NULL
, &arp_tbl
.parms
, "ipv4", NULL
);
1316 register_netdevice_notifier(&arp_netdev_notifier
);
1319 #ifdef CONFIG_PROC_FS
1320 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1322 /* ------------------------------------------------------------------------ */
1324 * ax25 -> ASCII conversion
1326 static char *ax2asc2(ax25_address
*a
, char *buf
)
1331 for (n
= 0, s
= buf
; n
< 6; n
++) {
1332 c
= (a
->ax25_call
[n
] >> 1) & 0x7F;
1339 n
= (a
->ax25_call
[6] >> 1) & 0x0F;
1348 if (*buf
== '\0' || *buf
== '-')
1353 #endif /* CONFIG_AX25 */
1355 #define HBUFFERLEN 30
1357 static void arp_format_neigh_entry(struct seq_file
*seq
,
1358 struct neighbour
*n
)
1360 char hbuffer
[HBUFFERLEN
];
1363 struct net_device
*dev
= n
->dev
;
1364 int hatype
= dev
->type
;
1366 read_lock(&n
->lock
);
1367 /* Convert hardware address to XX:XX:XX:XX ... form. */
1368 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1369 if (hatype
== ARPHRD_AX25
|| hatype
== ARPHRD_NETROM
)
1370 ax2asc2((ax25_address
*)n
->ha
, hbuffer
);
1373 for (k
= 0, j
= 0; k
< HBUFFERLEN
- 3 && j
< dev
->addr_len
; j
++) {
1374 hbuffer
[k
++] = hex_asc_hi(n
->ha
[j
]);
1375 hbuffer
[k
++] = hex_asc_lo(n
->ha
[j
]);
1381 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
1384 sprintf(tbuf
, "%pI4", n
->primary_key
);
1385 seq_printf(seq
, "%-16s 0x%-10x0x%-10x%s * %s\n",
1386 tbuf
, hatype
, arp_state_to_flags(n
), hbuffer
, dev
->name
);
1387 read_unlock(&n
->lock
);
1390 static void arp_format_pneigh_entry(struct seq_file
*seq
,
1391 struct pneigh_entry
*n
)
1393 struct net_device
*dev
= n
->dev
;
1394 int hatype
= dev
? dev
->type
: 0;
1397 sprintf(tbuf
, "%pI4", n
->key
);
1398 seq_printf(seq
, "%-16s 0x%-10x0x%-10x%s * %s\n",
1399 tbuf
, hatype
, ATF_PUBL
| ATF_PERM
, "00:00:00:00:00:00",
1400 dev
? dev
->name
: "*");
1403 static int arp_seq_show(struct seq_file
*seq
, void *v
)
1405 if (v
== SEQ_START_TOKEN
) {
1406 seq_puts(seq
, "IP address HW type Flags "
1407 "HW address Mask Device\n");
1409 struct neigh_seq_state
*state
= seq
->private;
1411 if (state
->flags
& NEIGH_SEQ_IS_PNEIGH
)
1412 arp_format_pneigh_entry(seq
, v
);
1414 arp_format_neigh_entry(seq
, v
);
1420 static void *arp_seq_start(struct seq_file
*seq
, loff_t
*pos
)
1422 /* Don't want to confuse "arp -a" w/ magic entries,
1423 * so we tell the generic iterator to skip NUD_NOARP.
1425 return neigh_seq_start(seq
, pos
, &arp_tbl
, NEIGH_SEQ_SKIP_NOARP
);
1428 /* ------------------------------------------------------------------------ */
1430 static const struct seq_operations arp_seq_ops
= {
1431 .start
= arp_seq_start
,
1432 .next
= neigh_seq_next
,
1433 .stop
= neigh_seq_stop
,
1434 .show
= arp_seq_show
,
1437 static int arp_seq_open(struct inode
*inode
, struct file
*file
)
1439 return seq_open_net(inode
, file
, &arp_seq_ops
,
1440 sizeof(struct neigh_seq_state
));
1443 static const struct file_operations arp_seq_fops
= {
1444 .owner
= THIS_MODULE
,
1445 .open
= arp_seq_open
,
1447 .llseek
= seq_lseek
,
1448 .release
= seq_release_net
,
1452 static int __net_init
arp_net_init(struct net
*net
)
1454 if (!proc_net_fops_create(net
, "arp", S_IRUGO
, &arp_seq_fops
))
1459 static void __net_exit
arp_net_exit(struct net
*net
)
1461 proc_net_remove(net
, "arp");
1464 static struct pernet_operations arp_net_ops
= {
1465 .init
= arp_net_init
,
1466 .exit
= arp_net_exit
,
1469 static int __init
arp_proc_init(void)
1471 return register_pernet_subsys(&arp_net_ops
);
1474 #else /* CONFIG_PROC_FS */
1476 static int __init
arp_proc_init(void)
1481 #endif /* CONFIG_PROC_FS */