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 struct neigh_table arp_tbl
= {
156 .constructor
= arp_constructor
,
157 .proxy_redo
= parp_redo
,
161 .reachable_time
= 30 * HZ
,
163 [NEIGH_VAR_MCAST_PROBES
] = 3,
164 [NEIGH_VAR_UCAST_PROBES
] = 3,
165 [NEIGH_VAR_RETRANS_TIME
] = 1 * HZ
,
166 [NEIGH_VAR_BASE_REACHABLE_TIME
] = 30 * HZ
,
167 [NEIGH_VAR_DELAY_PROBE_TIME
] = 5 * HZ
,
168 [NEIGH_VAR_GC_STALETIME
] = 60 * HZ
,
169 [NEIGH_VAR_QUEUE_LEN_BYTES
] = 64 * 1024,
170 [NEIGH_VAR_PROXY_QLEN
] = 64,
171 [NEIGH_VAR_ANYCAST_DELAY
] = 1 * HZ
,
172 [NEIGH_VAR_PROXY_DELAY
] = (8 * HZ
) / 10,
173 [NEIGH_VAR_LOCKTIME
] = 1 * HZ
,
176 .gc_interval
= 30 * HZ
,
181 EXPORT_SYMBOL(arp_tbl
);
183 int arp_mc_map(__be32 addr
, u8
*haddr
, struct net_device
*dev
, int dir
)
189 ip_eth_mc_map(addr
, haddr
);
191 case ARPHRD_INFINIBAND
:
192 ip_ib_mc_map(addr
, dev
->broadcast
, haddr
);
195 ip_ipgre_mc_map(addr
, dev
->broadcast
, haddr
);
199 memcpy(haddr
, dev
->broadcast
, dev
->addr_len
);
207 static u32
arp_hash(const void *pkey
,
208 const struct net_device
*dev
,
211 return arp_hashfn(*(u32
*)pkey
, dev
, *hash_rnd
);
214 static int arp_constructor(struct neighbour
*neigh
)
216 __be32 addr
= *(__be32
*)neigh
->primary_key
;
217 struct net_device
*dev
= neigh
->dev
;
218 struct in_device
*in_dev
;
219 struct neigh_parms
*parms
;
222 in_dev
= __in_dev_get_rcu(dev
);
223 if (in_dev
== NULL
) {
228 neigh
->type
= inet_addr_type(dev_net(dev
), addr
);
230 parms
= in_dev
->arp_parms
;
231 __neigh_parms_put(neigh
->parms
);
232 neigh
->parms
= neigh_parms_clone(parms
);
235 if (!dev
->header_ops
) {
236 neigh
->nud_state
= NUD_NOARP
;
237 neigh
->ops
= &arp_direct_ops
;
238 neigh
->output
= neigh_direct_output
;
240 /* Good devices (checked by reading texts, but only Ethernet is
243 ARPHRD_ETHER: (ethernet, apfddi)
246 ARPHRD_METRICOM: (strip)
250 ARPHRD_IPDDP will also work, if author repairs it.
251 I did not it, because this driver does not work even
255 if (neigh
->type
== RTN_MULTICAST
) {
256 neigh
->nud_state
= NUD_NOARP
;
257 arp_mc_map(addr
, neigh
->ha
, dev
, 1);
258 } else if (dev
->flags
& (IFF_NOARP
| IFF_LOOPBACK
)) {
259 neigh
->nud_state
= NUD_NOARP
;
260 memcpy(neigh
->ha
, dev
->dev_addr
, dev
->addr_len
);
261 } else if (neigh
->type
== RTN_BROADCAST
||
262 (dev
->flags
& IFF_POINTOPOINT
)) {
263 neigh
->nud_state
= NUD_NOARP
;
264 memcpy(neigh
->ha
, dev
->broadcast
, dev
->addr_len
);
267 if (dev
->header_ops
->cache
)
268 neigh
->ops
= &arp_hh_ops
;
270 neigh
->ops
= &arp_generic_ops
;
272 if (neigh
->nud_state
& NUD_VALID
)
273 neigh
->output
= neigh
->ops
->connected_output
;
275 neigh
->output
= neigh
->ops
->output
;
280 static void arp_error_report(struct neighbour
*neigh
, struct sk_buff
*skb
)
282 dst_link_failure(skb
);
286 static void arp_solicit(struct neighbour
*neigh
, struct sk_buff
*skb
)
289 u8 dst_ha
[MAX_ADDR_LEN
], *dst_hw
= NULL
;
290 struct net_device
*dev
= neigh
->dev
;
291 __be32 target
= *(__be32
*)neigh
->primary_key
;
292 int probes
= atomic_read(&neigh
->probes
);
293 struct in_device
*in_dev
;
296 in_dev
= __in_dev_get_rcu(dev
);
301 switch (IN_DEV_ARP_ANNOUNCE(in_dev
)) {
303 case 0: /* By default announce any local IP */
304 if (skb
&& inet_addr_type(dev_net(dev
),
305 ip_hdr(skb
)->saddr
) == RTN_LOCAL
)
306 saddr
= ip_hdr(skb
)->saddr
;
308 case 1: /* Restrict announcements of saddr in same subnet */
311 saddr
= ip_hdr(skb
)->saddr
;
312 if (inet_addr_type(dev_net(dev
), saddr
) == RTN_LOCAL
) {
313 /* saddr should be known to target */
314 if (inet_addr_onlink(in_dev
, target
, saddr
))
319 case 2: /* Avoid secondary IPs, get a primary/preferred one */
325 saddr
= inet_select_addr(dev
, target
, RT_SCOPE_LINK
);
327 probes
-= NEIGH_VAR(neigh
->parms
, UCAST_PROBES
);
329 if (!(neigh
->nud_state
& NUD_VALID
))
330 pr_debug("trying to ucast probe in NUD_INVALID\n");
331 neigh_ha_snapshot(dst_ha
, neigh
, dev
);
334 probes
-= NEIGH_VAR(neigh
->parms
, APP_PROBES
);
341 arp_send(ARPOP_REQUEST
, ETH_P_ARP
, target
, dev
, saddr
,
342 dst_hw
, dev
->dev_addr
, NULL
);
345 static int arp_ignore(struct in_device
*in_dev
, __be32 sip
, __be32 tip
)
347 struct net
*net
= dev_net(in_dev
->dev
);
350 switch (IN_DEV_ARP_IGNORE(in_dev
)) {
351 case 0: /* Reply, the tip is already validated */
353 case 1: /* Reply only if tip is configured on the incoming interface */
355 scope
= RT_SCOPE_HOST
;
358 * Reply only if tip is configured on the incoming interface
359 * and is in same subnet as sip
361 scope
= RT_SCOPE_HOST
;
363 case 3: /* Do not reply for scope host addresses */
365 scope
= RT_SCOPE_LINK
;
368 case 4: /* Reserved */
373 case 8: /* Do not reply */
378 return !inet_confirm_addr(net
, in_dev
, sip
, tip
, scope
);
381 static int arp_filter(__be32 sip
, __be32 tip
, struct net_device
*dev
)
385 /*unsigned long now; */
386 struct net
*net
= dev_net(dev
);
388 rt
= ip_route_output(net
, sip
, tip
, 0, 0);
391 if (rt
->dst
.dev
!= dev
) {
392 NET_INC_STATS_BH(net
, LINUX_MIB_ARPFILTER
);
400 * Check if we can use proxy ARP for this path
402 static inline int arp_fwd_proxy(struct in_device
*in_dev
,
403 struct net_device
*dev
, struct rtable
*rt
)
405 struct in_device
*out_dev
;
408 if (rt
->dst
.dev
== dev
)
411 if (!IN_DEV_PROXY_ARP(in_dev
))
413 imi
= IN_DEV_MEDIUM_ID(in_dev
);
419 /* place to check for proxy_arp for routes */
421 out_dev
= __in_dev_get_rcu(rt
->dst
.dev
);
423 omi
= IN_DEV_MEDIUM_ID(out_dev
);
425 return omi
!= imi
&& omi
!= -1;
429 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
431 * RFC3069 supports proxy arp replies back to the same interface. This
432 * is done to support (ethernet) switch features, like RFC 3069, where
433 * the individual ports are not allowed to communicate with each
434 * other, BUT they are allowed to talk to the upstream router. As
435 * described in RFC 3069, it is possible to allow these hosts to
436 * communicate through the upstream router, by proxy_arp'ing.
438 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
440 * This technology is known by different names:
441 * In RFC 3069 it is called VLAN Aggregation.
442 * Cisco and Allied Telesyn call it Private VLAN.
443 * Hewlett-Packard call it Source-Port filtering or port-isolation.
444 * Ericsson call it MAC-Forced Forwarding (RFC Draft).
447 static inline int arp_fwd_pvlan(struct in_device
*in_dev
,
448 struct net_device
*dev
, struct rtable
*rt
,
449 __be32 sip
, __be32 tip
)
451 /* Private VLAN is only concerned about the same ethernet segment */
452 if (rt
->dst
.dev
!= dev
)
455 /* Don't reply on self probes (often done by windowz boxes)*/
459 if (IN_DEV_PROXY_ARP_PVLAN(in_dev
))
466 * Interface to link layer: send routine and receive handler.
470 * Create an arp packet. If (dest_hw == NULL), we create a broadcast
473 struct sk_buff
*arp_create(int type
, int ptype
, __be32 dest_ip
,
474 struct net_device
*dev
, __be32 src_ip
,
475 const unsigned char *dest_hw
,
476 const unsigned char *src_hw
,
477 const unsigned char *target_hw
)
481 unsigned char *arp_ptr
;
482 int hlen
= LL_RESERVED_SPACE(dev
);
483 int tlen
= dev
->needed_tailroom
;
489 skb
= alloc_skb(arp_hdr_len(dev
) + hlen
+ tlen
, GFP_ATOMIC
);
493 skb_reserve(skb
, hlen
);
494 skb_reset_network_header(skb
);
495 arp
= (struct arphdr
*) skb_put(skb
, arp_hdr_len(dev
));
497 skb
->protocol
= htons(ETH_P_ARP
);
499 src_hw
= dev
->dev_addr
;
501 dest_hw
= dev
->broadcast
;
504 * Fill the device header for the ARP frame
506 if (dev_hard_header(skb
, dev
, ptype
, dest_hw
, src_hw
, skb
->len
) < 0)
510 * Fill out the arp protocol part.
512 * The arp hardware type should match the device type, except for FDDI,
513 * which (according to RFC 1390) should always equal 1 (Ethernet).
516 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
517 * DIX code for the protocol. Make these device structure fields.
521 arp
->ar_hrd
= htons(dev
->type
);
522 arp
->ar_pro
= htons(ETH_P_IP
);
525 #if IS_ENABLED(CONFIG_AX25)
527 arp
->ar_hrd
= htons(ARPHRD_AX25
);
528 arp
->ar_pro
= htons(AX25_P_IP
);
531 #if IS_ENABLED(CONFIG_NETROM)
533 arp
->ar_hrd
= htons(ARPHRD_NETROM
);
534 arp
->ar_pro
= htons(AX25_P_IP
);
539 #if IS_ENABLED(CONFIG_FDDI)
541 arp
->ar_hrd
= htons(ARPHRD_ETHER
);
542 arp
->ar_pro
= htons(ETH_P_IP
);
547 arp
->ar_hln
= dev
->addr_len
;
549 arp
->ar_op
= htons(type
);
551 arp_ptr
= (unsigned char *)(arp
+ 1);
553 memcpy(arp_ptr
, src_hw
, dev
->addr_len
);
554 arp_ptr
+= dev
->addr_len
;
555 memcpy(arp_ptr
, &src_ip
, 4);
559 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
560 case ARPHRD_IEEE1394
:
564 if (target_hw
!= NULL
)
565 memcpy(arp_ptr
, target_hw
, dev
->addr_len
);
567 memset(arp_ptr
, 0, dev
->addr_len
);
568 arp_ptr
+= dev
->addr_len
;
570 memcpy(arp_ptr
, &dest_ip
, 4);
578 EXPORT_SYMBOL(arp_create
);
581 * Send an arp packet.
583 void arp_xmit(struct sk_buff
*skb
)
585 /* Send it off, maybe filter it using firewalling first. */
586 NF_HOOK(NFPROTO_ARP
, NF_ARP_OUT
, skb
, NULL
, skb
->dev
, dev_queue_xmit
);
588 EXPORT_SYMBOL(arp_xmit
);
591 * Create and send an arp packet.
593 void arp_send(int type
, int ptype
, __be32 dest_ip
,
594 struct net_device
*dev
, __be32 src_ip
,
595 const unsigned char *dest_hw
, const unsigned char *src_hw
,
596 const unsigned char *target_hw
)
601 * No arp on this interface.
604 if (dev
->flags
&IFF_NOARP
)
607 skb
= arp_create(type
, ptype
, dest_ip
, dev
, src_ip
,
608 dest_hw
, src_hw
, target_hw
);
614 EXPORT_SYMBOL(arp_send
);
617 * Process an arp request.
620 static int arp_process(struct sk_buff
*skb
)
622 struct net_device
*dev
= skb
->dev
;
623 struct in_device
*in_dev
= __in_dev_get_rcu(dev
);
625 unsigned char *arp_ptr
;
629 u16 dev_type
= dev
->type
;
632 struct net
*net
= dev_net(dev
);
633 bool is_garp
= false;
635 /* arp_rcv below verifies the ARP header and verifies the device
646 if (arp
->ar_pro
!= htons(ETH_P_IP
) ||
647 htons(dev_type
) != arp
->ar_hrd
)
654 * ETHERNET, and Fibre Channel (which are IEEE 802
655 * devices, according to RFC 2625) devices will accept ARP
656 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
657 * This is the case also of FDDI, where the RFC 1390 says that
658 * FDDI devices should accept ARP hardware of (1) Ethernet,
659 * however, to be more robust, we'll accept both 1 (Ethernet)
662 if ((arp
->ar_hrd
!= htons(ARPHRD_ETHER
) &&
663 arp
->ar_hrd
!= htons(ARPHRD_IEEE802
)) ||
664 arp
->ar_pro
!= htons(ETH_P_IP
))
668 if (arp
->ar_pro
!= htons(AX25_P_IP
) ||
669 arp
->ar_hrd
!= htons(ARPHRD_AX25
))
673 if (arp
->ar_pro
!= htons(AX25_P_IP
) ||
674 arp
->ar_hrd
!= htons(ARPHRD_NETROM
))
679 /* Understand only these message types */
681 if (arp
->ar_op
!= htons(ARPOP_REPLY
) &&
682 arp
->ar_op
!= htons(ARPOP_REQUEST
))
688 arp_ptr
= (unsigned char *)(arp
+ 1);
690 arp_ptr
+= dev
->addr_len
;
691 memcpy(&sip
, arp_ptr
, 4);
694 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
695 case ARPHRD_IEEE1394
:
699 arp_ptr
+= dev
->addr_len
;
701 memcpy(&tip
, arp_ptr
, 4);
703 * Check for bad requests for 127.x.x.x and requests for multicast
704 * addresses. If this is one such, delete it.
706 if (ipv4_is_multicast(tip
) ||
707 (!IN_DEV_ROUTE_LOCALNET(in_dev
) && ipv4_is_loopback(tip
)))
711 * Special case: We must set Frame Relay source Q.922 address
713 if (dev_type
== ARPHRD_DLCI
)
714 sha
= dev
->broadcast
;
717 * Process entry. The idea here is we want to send a reply if it is a
718 * request for us or if it is a request for someone else that we hold
719 * a proxy for. We want to add an entry to our cache if it is a reply
720 * to us or if it is a request for our address.
721 * (The assumption for this last is that if someone is requesting our
722 * address, they are probably intending to talk to us, so it saves time
723 * if we cache their address. Their address is also probably not in
724 * our cache, since ours is not in their cache.)
726 * Putting this another way, we only care about replies if they are to
727 * us, in which case we add them to the cache. For requests, we care
728 * about those for us and those for our proxies. We reply to both,
729 * and in the case of requests for us we add the requester to the arp
733 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
735 if (arp
->ar_op
== htons(ARPOP_REQUEST
) &&
736 inet_addr_type(net
, tip
) == RTN_LOCAL
&&
737 !arp_ignore(in_dev
, sip
, tip
))
738 arp_send(ARPOP_REPLY
, ETH_P_ARP
, sip
, dev
, tip
, sha
,
743 if (arp
->ar_op
== htons(ARPOP_REQUEST
) &&
744 ip_route_input_noref(skb
, tip
, sip
, 0, dev
) == 0) {
746 rt
= skb_rtable(skb
);
747 addr_type
= rt
->rt_type
;
749 if (addr_type
== RTN_LOCAL
) {
752 dont_send
= arp_ignore(in_dev
, sip
, tip
);
753 if (!dont_send
&& IN_DEV_ARPFILTER(in_dev
))
754 dont_send
= arp_filter(sip
, tip
, dev
);
756 n
= neigh_event_ns(&arp_tbl
, sha
, &sip
, dev
);
758 arp_send(ARPOP_REPLY
, ETH_P_ARP
, sip
,
759 dev
, tip
, sha
, dev
->dev_addr
,
765 } else if (IN_DEV_FORWARD(in_dev
)) {
766 if (addr_type
== RTN_UNICAST
&&
767 (arp_fwd_proxy(in_dev
, dev
, rt
) ||
768 arp_fwd_pvlan(in_dev
, dev
, rt
, sip
, tip
) ||
769 (rt
->dst
.dev
!= dev
&&
770 pneigh_lookup(&arp_tbl
, net
, &tip
, dev
, 0)))) {
771 n
= neigh_event_ns(&arp_tbl
, sha
, &sip
, dev
);
775 if (NEIGH_CB(skb
)->flags
& LOCALLY_ENQUEUED
||
776 skb
->pkt_type
== PACKET_HOST
||
777 NEIGH_VAR(in_dev
->arp_parms
, PROXY_DELAY
) == 0) {
778 arp_send(ARPOP_REPLY
, ETH_P_ARP
, sip
,
779 dev
, tip
, sha
, dev
->dev_addr
,
782 pneigh_enqueue(&arp_tbl
,
783 in_dev
->arp_parms
, skb
);
791 /* Update our ARP tables */
793 n
= __neigh_lookup(&arp_tbl
, &sip
, dev
, 0);
795 if (IN_DEV_ARP_ACCEPT(in_dev
)) {
796 /* Unsolicited ARP is not accepted by default.
797 It is possible, that this option should be enabled for some
798 devices (strip is candidate)
800 is_garp
= arp
->ar_op
== htons(ARPOP_REQUEST
) && tip
== sip
&&
801 inet_addr_type(net
, sip
) == RTN_UNICAST
;
804 ((arp
->ar_op
== htons(ARPOP_REPLY
) &&
805 inet_addr_type(net
, sip
) == RTN_UNICAST
) || is_garp
))
806 n
= __neigh_lookup(&arp_tbl
, &sip
, dev
, 1);
810 int state
= NUD_REACHABLE
;
813 /* If several different ARP replies follows back-to-back,
814 use the FIRST one. It is possible, if several proxy
815 agents are active. Taking the first reply prevents
816 arp trashing and chooses the fastest router.
818 override
= time_after(jiffies
,
820 NEIGH_VAR(n
->parms
, LOCKTIME
)) ||
823 /* Broadcast replies and request packets
824 do not assert neighbour reachability.
826 if (arp
->ar_op
!= htons(ARPOP_REPLY
) ||
827 skb
->pkt_type
!= PACKET_HOST
)
829 neigh_update(n
, sha
, state
,
830 override
? NEIGH_UPDATE_F_OVERRIDE
: 0);
839 static void parp_redo(struct sk_buff
*skb
)
846 * Receive an arp request from the device layer.
849 static int arp_rcv(struct sk_buff
*skb
, struct net_device
*dev
,
850 struct packet_type
*pt
, struct net_device
*orig_dev
)
852 const struct arphdr
*arp
;
854 /* do not tweak dropwatch on an ARP we will ignore */
855 if (dev
->flags
& IFF_NOARP
||
856 skb
->pkt_type
== PACKET_OTHERHOST
||
857 skb
->pkt_type
== PACKET_LOOPBACK
)
860 skb
= skb_share_check(skb
, GFP_ATOMIC
);
864 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
865 if (!pskb_may_pull(skb
, arp_hdr_len(dev
)))
869 if (arp
->ar_hln
!= dev
->addr_len
|| arp
->ar_pln
!= 4)
872 memset(NEIGH_CB(skb
), 0, sizeof(struct neighbour_cb
));
874 return NF_HOOK(NFPROTO_ARP
, NF_ARP_IN
, skb
, dev
, NULL
, arp_process
);
886 * User level interface (ioctl)
890 * Set (create) an ARP cache entry.
893 static int arp_req_set_proxy(struct net
*net
, struct net_device
*dev
, int on
)
896 IPV4_DEVCONF_ALL(net
, PROXY_ARP
) = on
;
899 if (__in_dev_get_rtnl(dev
)) {
900 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev
), PROXY_ARP
, on
);
906 static int arp_req_set_public(struct net
*net
, struct arpreq
*r
,
907 struct net_device
*dev
)
909 __be32 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
910 __be32 mask
= ((struct sockaddr_in
*)&r
->arp_netmask
)->sin_addr
.s_addr
;
912 if (mask
&& mask
!= htonl(0xFFFFFFFF))
914 if (!dev
&& (r
->arp_flags
& ATF_COM
)) {
915 dev
= dev_getbyhwaddr_rcu(net
, r
->arp_ha
.sa_family
,
921 if (pneigh_lookup(&arp_tbl
, net
, &ip
, dev
, 1) == NULL
)
926 return arp_req_set_proxy(net
, dev
, 1);
929 static int arp_req_set(struct net
*net
, struct arpreq
*r
,
930 struct net_device
*dev
)
933 struct neighbour
*neigh
;
936 if (r
->arp_flags
& ATF_PUBL
)
937 return arp_req_set_public(net
, r
, dev
);
939 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
940 if (r
->arp_flags
& ATF_PERM
)
941 r
->arp_flags
|= ATF_COM
;
943 struct rtable
*rt
= ip_route_output(net
, ip
, 0, RTO_ONLINK
, 0);
953 #if IS_ENABLED(CONFIG_FDDI)
956 * According to RFC 1390, FDDI devices should accept ARP
957 * hardware types of 1 (Ethernet). However, to be more
958 * robust, we'll accept hardware types of either 1 (Ethernet)
961 if (r
->arp_ha
.sa_family
!= ARPHRD_FDDI
&&
962 r
->arp_ha
.sa_family
!= ARPHRD_ETHER
&&
963 r
->arp_ha
.sa_family
!= ARPHRD_IEEE802
)
968 if (r
->arp_ha
.sa_family
!= dev
->type
)
973 neigh
= __neigh_lookup_errno(&arp_tbl
, &ip
, dev
);
974 err
= PTR_ERR(neigh
);
975 if (!IS_ERR(neigh
)) {
976 unsigned int state
= NUD_STALE
;
977 if (r
->arp_flags
& ATF_PERM
)
978 state
= NUD_PERMANENT
;
979 err
= neigh_update(neigh
, (r
->arp_flags
& ATF_COM
) ?
980 r
->arp_ha
.sa_data
: NULL
, state
,
981 NEIGH_UPDATE_F_OVERRIDE
|
982 NEIGH_UPDATE_F_ADMIN
);
983 neigh_release(neigh
);
988 static unsigned int arp_state_to_flags(struct neighbour
*neigh
)
990 if (neigh
->nud_state
&NUD_PERMANENT
)
991 return ATF_PERM
| ATF_COM
;
992 else if (neigh
->nud_state
&NUD_VALID
)
999 * Get an ARP cache entry.
1002 static int arp_req_get(struct arpreq
*r
, struct net_device
*dev
)
1004 __be32 ip
= ((struct sockaddr_in
*) &r
->arp_pa
)->sin_addr
.s_addr
;
1005 struct neighbour
*neigh
;
1008 neigh
= neigh_lookup(&arp_tbl
, &ip
, dev
);
1010 read_lock_bh(&neigh
->lock
);
1011 memcpy(r
->arp_ha
.sa_data
, neigh
->ha
, dev
->addr_len
);
1012 r
->arp_flags
= arp_state_to_flags(neigh
);
1013 read_unlock_bh(&neigh
->lock
);
1014 r
->arp_ha
.sa_family
= dev
->type
;
1015 strlcpy(r
->arp_dev
, dev
->name
, sizeof(r
->arp_dev
));
1016 neigh_release(neigh
);
1022 static int arp_invalidate(struct net_device
*dev
, __be32 ip
)
1024 struct neighbour
*neigh
= neigh_lookup(&arp_tbl
, &ip
, dev
);
1028 if (neigh
->nud_state
& ~NUD_NOARP
)
1029 err
= neigh_update(neigh
, NULL
, NUD_FAILED
,
1030 NEIGH_UPDATE_F_OVERRIDE
|
1031 NEIGH_UPDATE_F_ADMIN
);
1032 neigh_release(neigh
);
1038 static int arp_req_delete_public(struct net
*net
, struct arpreq
*r
,
1039 struct net_device
*dev
)
1041 __be32 ip
= ((struct sockaddr_in
*) &r
->arp_pa
)->sin_addr
.s_addr
;
1042 __be32 mask
= ((struct sockaddr_in
*)&r
->arp_netmask
)->sin_addr
.s_addr
;
1044 if (mask
== htonl(0xFFFFFFFF))
1045 return pneigh_delete(&arp_tbl
, net
, &ip
, dev
);
1050 return arp_req_set_proxy(net
, dev
, 0);
1053 static int arp_req_delete(struct net
*net
, struct arpreq
*r
,
1054 struct net_device
*dev
)
1058 if (r
->arp_flags
& ATF_PUBL
)
1059 return arp_req_delete_public(net
, r
, dev
);
1061 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
1063 struct rtable
*rt
= ip_route_output(net
, ip
, 0, RTO_ONLINK
, 0);
1071 return arp_invalidate(dev
, ip
);
1075 * Handle an ARP layer I/O control request.
1078 int arp_ioctl(struct net
*net
, unsigned int cmd
, void __user
*arg
)
1082 struct net_device
*dev
= NULL
;
1087 if (!ns_capable(net
->user_ns
, CAP_NET_ADMIN
))
1090 err
= copy_from_user(&r
, arg
, sizeof(struct arpreq
));
1098 if (r
.arp_pa
.sa_family
!= AF_INET
)
1099 return -EPFNOSUPPORT
;
1101 if (!(r
.arp_flags
& ATF_PUBL
) &&
1102 (r
.arp_flags
& (ATF_NETMASK
| ATF_DONTPUB
)))
1104 if (!(r
.arp_flags
& ATF_NETMASK
))
1105 ((struct sockaddr_in
*)&r
.arp_netmask
)->sin_addr
.s_addr
=
1106 htonl(0xFFFFFFFFUL
);
1110 dev
= __dev_get_by_name(net
, r
.arp_dev
);
1114 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1115 if (!r
.arp_ha
.sa_family
)
1116 r
.arp_ha
.sa_family
= dev
->type
;
1118 if ((r
.arp_flags
& ATF_COM
) && r
.arp_ha
.sa_family
!= dev
->type
)
1120 } else if (cmd
== SIOCGARP
) {
1127 err
= arp_req_delete(net
, &r
, dev
);
1130 err
= arp_req_set(net
, &r
, dev
);
1133 err
= arp_req_get(&r
, dev
);
1138 if (cmd
== SIOCGARP
&& !err
&& copy_to_user(arg
, &r
, sizeof(r
)))
1143 static int arp_netdev_event(struct notifier_block
*this, unsigned long event
,
1146 struct net_device
*dev
= netdev_notifier_info_to_dev(ptr
);
1147 struct netdev_notifier_change_info
*change_info
;
1150 case NETDEV_CHANGEADDR
:
1151 neigh_changeaddr(&arp_tbl
, dev
);
1152 rt_cache_flush(dev_net(dev
));
1156 if (change_info
->flags_changed
& IFF_NOARP
)
1157 neigh_changeaddr(&arp_tbl
, dev
);
1166 static struct notifier_block arp_netdev_notifier
= {
1167 .notifier_call
= arp_netdev_event
,
1170 /* Note, that it is not on notifier chain.
1171 It is necessary, that this routine was called after route cache will be
1174 void arp_ifdown(struct net_device
*dev
)
1176 neigh_ifdown(&arp_tbl
, dev
);
1181 * Called once on startup.
1184 static struct packet_type arp_packet_type __read_mostly
= {
1185 .type
= cpu_to_be16(ETH_P_ARP
),
1189 static int arp_proc_init(void);
1191 void __init
arp_init(void)
1193 neigh_table_init(NEIGH_ARP_TABLE
, &arp_tbl
);
1195 dev_add_pack(&arp_packet_type
);
1197 #ifdef CONFIG_SYSCTL
1198 neigh_sysctl_register(NULL
, &arp_tbl
.parms
, NULL
);
1200 register_netdevice_notifier(&arp_netdev_notifier
);
1203 #ifdef CONFIG_PROC_FS
1204 #if IS_ENABLED(CONFIG_AX25)
1206 /* ------------------------------------------------------------------------ */
1208 * ax25 -> ASCII conversion
1210 static char *ax2asc2(ax25_address
*a
, char *buf
)
1215 for (n
= 0, s
= buf
; n
< 6; n
++) {
1216 c
= (a
->ax25_call
[n
] >> 1) & 0x7F;
1223 n
= (a
->ax25_call
[6] >> 1) & 0x0F;
1232 if (*buf
== '\0' || *buf
== '-')
1237 #endif /* CONFIG_AX25 */
1239 #define HBUFFERLEN 30
1241 static void arp_format_neigh_entry(struct seq_file
*seq
,
1242 struct neighbour
*n
)
1244 char hbuffer
[HBUFFERLEN
];
1247 struct net_device
*dev
= n
->dev
;
1248 int hatype
= dev
->type
;
1250 read_lock(&n
->lock
);
1251 /* Convert hardware address to XX:XX:XX:XX ... form. */
1252 #if IS_ENABLED(CONFIG_AX25)
1253 if (hatype
== ARPHRD_AX25
|| hatype
== ARPHRD_NETROM
)
1254 ax2asc2((ax25_address
*)n
->ha
, hbuffer
);
1257 for (k
= 0, j
= 0; k
< HBUFFERLEN
- 3 && j
< dev
->addr_len
; j
++) {
1258 hbuffer
[k
++] = hex_asc_hi(n
->ha
[j
]);
1259 hbuffer
[k
++] = hex_asc_lo(n
->ha
[j
]);
1265 #if IS_ENABLED(CONFIG_AX25)
1268 sprintf(tbuf
, "%pI4", n
->primary_key
);
1269 seq_printf(seq
, "%-16s 0x%-10x0x%-10x%s * %s\n",
1270 tbuf
, hatype
, arp_state_to_flags(n
), hbuffer
, dev
->name
);
1271 read_unlock(&n
->lock
);
1274 static void arp_format_pneigh_entry(struct seq_file
*seq
,
1275 struct pneigh_entry
*n
)
1277 struct net_device
*dev
= n
->dev
;
1278 int hatype
= dev
? dev
->type
: 0;
1281 sprintf(tbuf
, "%pI4", n
->key
);
1282 seq_printf(seq
, "%-16s 0x%-10x0x%-10x%s * %s\n",
1283 tbuf
, hatype
, ATF_PUBL
| ATF_PERM
, "00:00:00:00:00:00",
1284 dev
? dev
->name
: "*");
1287 static int arp_seq_show(struct seq_file
*seq
, void *v
)
1289 if (v
== SEQ_START_TOKEN
) {
1290 seq_puts(seq
, "IP address HW type Flags "
1291 "HW address Mask Device\n");
1293 struct neigh_seq_state
*state
= seq
->private;
1295 if (state
->flags
& NEIGH_SEQ_IS_PNEIGH
)
1296 arp_format_pneigh_entry(seq
, v
);
1298 arp_format_neigh_entry(seq
, v
);
1304 static void *arp_seq_start(struct seq_file
*seq
, loff_t
*pos
)
1306 /* Don't want to confuse "arp -a" w/ magic entries,
1307 * so we tell the generic iterator to skip NUD_NOARP.
1309 return neigh_seq_start(seq
, pos
, &arp_tbl
, NEIGH_SEQ_SKIP_NOARP
);
1312 /* ------------------------------------------------------------------------ */
1314 static const struct seq_operations arp_seq_ops
= {
1315 .start
= arp_seq_start
,
1316 .next
= neigh_seq_next
,
1317 .stop
= neigh_seq_stop
,
1318 .show
= arp_seq_show
,
1321 static int arp_seq_open(struct inode
*inode
, struct file
*file
)
1323 return seq_open_net(inode
, file
, &arp_seq_ops
,
1324 sizeof(struct neigh_seq_state
));
1327 static const struct file_operations arp_seq_fops
= {
1328 .owner
= THIS_MODULE
,
1329 .open
= arp_seq_open
,
1331 .llseek
= seq_lseek
,
1332 .release
= seq_release_net
,
1336 static int __net_init
arp_net_init(struct net
*net
)
1338 if (!proc_create("arp", S_IRUGO
, net
->proc_net
, &arp_seq_fops
))
1343 static void __net_exit
arp_net_exit(struct net
*net
)
1345 remove_proc_entry("arp", net
->proc_net
);
1348 static struct pernet_operations arp_net_ops
= {
1349 .init
= arp_net_init
,
1350 .exit
= arp_net_exit
,
1353 static int __init
arp_proc_init(void)
1355 return register_pernet_subsys(&arp_net_ops
);
1358 #else /* CONFIG_PROC_FS */
1360 static int __init
arp_proc_init(void)
1365 #endif /* CONFIG_PROC_FS */