1 /* linux/net/ipv4/arp.c
3 * Copyright (C) 1994 by Florian La Roche
5 * This module implements the Address Resolution Protocol ARP (RFC 826),
6 * which is used to convert IP addresses (or in the future maybe other
7 * high-level addresses) into a low-level hardware address (like an Ethernet
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version
13 * 2 of the License, or (at your option) any later version.
16 * Alan Cox : Removed the Ethernet assumptions in
18 * Alan Cox : Fixed some small errors in the ARP
20 * Alan Cox : Allow >4K in /proc
21 * Alan Cox : Make ARP add its own protocol entry
22 * Ross Martin : Rewrote arp_rcv() and arp_get_info()
23 * Stephen Henson : Add AX25 support to arp_get_info()
24 * Alan Cox : Drop data when a device is downed.
25 * Alan Cox : Use init_timer().
26 * Alan Cox : Double lock fixes.
27 * Martin Seine : Move the arphdr structure
28 * to if_arp.h for compatibility.
29 * with BSD based programs.
30 * Andrew Tridgell : Added ARP netmask code and
31 * re-arranged proxy handling.
32 * Alan Cox : Changed to use notifiers.
33 * Niibe Yutaka : Reply for this device or proxies only.
34 * Alan Cox : Don't proxy across hardware types!
35 * Jonathan Naylor : Added support for NET/ROM.
36 * Mike Shaver : RFC1122 checks.
37 * Jonathan Naylor : Only lookup the hardware address for
38 * the correct hardware type.
39 * Germano Caronni : Assorted subtle races.
40 * Craig Schlenter : Don't modify permanent entry
42 * Russ Nelson : Tidied up a few bits.
43 * Alexey Kuznetsov: Major changes to caching and behaviour,
44 * eg intelligent arp probing and
46 * of host down events.
47 * Alan Cox : Missing unlock in device events.
48 * Eckes : ARP ioctl control errors.
49 * Alexey Kuznetsov: Arp free fix.
50 * Manuel Rodriguez: Gratuitous ARP.
51 * Jonathan Layes : Added arpd support through kerneld
52 * message queue (960314)
53 * Mike Shaver : /proc/sys/net/ipv4/arp_* support
54 * Mike McLagan : Routing by source
55 * Stuart Cheshire : Metricom and grat arp fixes
56 * *** FOR 2.1 clean this up ***
57 * Lawrence V. Stefani: (08/12/96) Added FDDI support.
58 * Alan Cox : Took the AP1000 nasty FDDI hack and
59 * folded into the mainstream FDDI code.
60 * Ack spit, Linus how did you allow that
62 * Jes Sorensen : Make FDDI work again in 2.1.x and
63 * clean up the APFDDI & gen. FDDI bits.
64 * Alexey Kuznetsov: new arp state machine;
65 * now it is in net/core/neighbour.c.
66 * Krzysztof Halasa: Added Frame Relay ARP support.
67 * Arnaldo C. Melo : convert /proc/net/arp to seq_file
68 * Shmulik Hen: Split arp_send to arp_create and
69 * arp_xmit so intermediate drivers like
70 * bonding can change the skb before
71 * sending (e.g. insert 8021q tag).
72 * Harald Welte : convert to make use of jenkins hash
73 * Jesper D. Brouer: Proxy ARP PVLAN RFC 3069 support.
76 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
78 #include <linux/module.h>
79 #include <linux/types.h>
80 #include <linux/string.h>
81 #include <linux/kernel.h>
82 #include <linux/capability.h>
83 #include <linux/socket.h>
84 #include <linux/sockios.h>
85 #include <linux/errno.h>
88 #include <linux/inet.h>
89 #include <linux/inetdevice.h>
90 #include <linux/netdevice.h>
91 #include <linux/etherdevice.h>
92 #include <linux/fddidevice.h>
93 #include <linux/if_arp.h>
94 #include <linux/skbuff.h>
95 #include <linux/proc_fs.h>
96 #include <linux/seq_file.h>
97 #include <linux/stat.h>
98 #include <linux/init.h>
99 #include <linux/net.h>
100 #include <linux/rcupdate.h>
101 #include <linux/slab.h>
103 #include <linux/sysctl.h>
106 #include <net/net_namespace.h>
108 #include <net/icmp.h>
109 #include <net/route.h>
110 #include <net/protocol.h>
112 #include <net/sock.h>
114 #include <net/ax25.h>
115 #include <net/netrom.h>
117 #include <linux/uaccess.h>
119 #include <linux/netfilter_arp.h>
122 * Interface to generic neighbour cache.
124 static u32
arp_hash(const void *pkey
, const struct net_device
*dev
, __u32
*hash_rnd
);
125 static bool arp_key_eq(const struct neighbour
*n
, const void *pkey
);
126 static int arp_constructor(struct neighbour
*neigh
);
127 static void arp_solicit(struct neighbour
*neigh
, struct sk_buff
*skb
);
128 static void arp_error_report(struct neighbour
*neigh
, struct sk_buff
*skb
);
129 static void parp_redo(struct sk_buff
*skb
);
131 static const struct neigh_ops arp_generic_ops
= {
133 .solicit
= arp_solicit
,
134 .error_report
= arp_error_report
,
135 .output
= neigh_resolve_output
,
136 .connected_output
= neigh_connected_output
,
139 static const struct neigh_ops arp_hh_ops
= {
141 .solicit
= arp_solicit
,
142 .error_report
= arp_error_report
,
143 .output
= neigh_resolve_output
,
144 .connected_output
= neigh_resolve_output
,
147 static const struct neigh_ops arp_direct_ops
= {
149 .output
= neigh_direct_output
,
150 .connected_output
= neigh_direct_output
,
153 struct neigh_table arp_tbl
= {
156 .protocol
= cpu_to_be16(ETH_P_IP
),
158 .key_eq
= arp_key_eq
,
159 .constructor
= arp_constructor
,
160 .proxy_redo
= parp_redo
,
164 .reachable_time
= 30 * HZ
,
166 [NEIGH_VAR_MCAST_PROBES
] = 3,
167 [NEIGH_VAR_UCAST_PROBES
] = 3,
168 [NEIGH_VAR_RETRANS_TIME
] = 1 * HZ
,
169 [NEIGH_VAR_BASE_REACHABLE_TIME
] = 30 * HZ
,
170 [NEIGH_VAR_DELAY_PROBE_TIME
] = 5 * HZ
,
171 [NEIGH_VAR_GC_STALETIME
] = 60 * HZ
,
172 [NEIGH_VAR_QUEUE_LEN_BYTES
] = 64 * 1024,
173 [NEIGH_VAR_PROXY_QLEN
] = 64,
174 [NEIGH_VAR_ANYCAST_DELAY
] = 1 * HZ
,
175 [NEIGH_VAR_PROXY_DELAY
] = (8 * HZ
) / 10,
176 [NEIGH_VAR_LOCKTIME
] = 1 * HZ
,
179 .gc_interval
= 30 * HZ
,
184 EXPORT_SYMBOL(arp_tbl
);
186 int arp_mc_map(__be32 addr
, u8
*haddr
, struct net_device
*dev
, int dir
)
192 ip_eth_mc_map(addr
, haddr
);
194 case ARPHRD_INFINIBAND
:
195 ip_ib_mc_map(addr
, dev
->broadcast
, haddr
);
198 ip_ipgre_mc_map(addr
, dev
->broadcast
, haddr
);
202 memcpy(haddr
, dev
->broadcast
, dev
->addr_len
);
210 static u32
arp_hash(const void *pkey
,
211 const struct net_device
*dev
,
214 return arp_hashfn(pkey
, dev
, hash_rnd
);
217 static bool arp_key_eq(const struct neighbour
*neigh
, const void *pkey
)
219 return neigh_key_eq32(neigh
, pkey
);
222 static int arp_constructor(struct neighbour
*neigh
)
224 __be32 addr
= *(__be32
*)neigh
->primary_key
;
225 struct net_device
*dev
= neigh
->dev
;
226 struct in_device
*in_dev
;
227 struct neigh_parms
*parms
;
230 in_dev
= __in_dev_get_rcu(dev
);
236 neigh
->type
= inet_addr_type_dev_table(dev_net(dev
), dev
, addr
);
238 parms
= in_dev
->arp_parms
;
239 __neigh_parms_put(neigh
->parms
);
240 neigh
->parms
= neigh_parms_clone(parms
);
243 if (!dev
->header_ops
) {
244 neigh
->nud_state
= NUD_NOARP
;
245 neigh
->ops
= &arp_direct_ops
;
246 neigh
->output
= neigh_direct_output
;
248 /* Good devices (checked by reading texts, but only Ethernet is
251 ARPHRD_ETHER: (ethernet, apfddi)
254 ARPHRD_METRICOM: (strip)
258 ARPHRD_IPDDP will also work, if author repairs it.
259 I did not it, because this driver does not work even
263 if (neigh
->type
== RTN_MULTICAST
) {
264 neigh
->nud_state
= NUD_NOARP
;
265 arp_mc_map(addr
, neigh
->ha
, dev
, 1);
266 } else if (dev
->flags
& (IFF_NOARP
| IFF_LOOPBACK
)) {
267 neigh
->nud_state
= NUD_NOARP
;
268 memcpy(neigh
->ha
, dev
->dev_addr
, dev
->addr_len
);
269 } else if (neigh
->type
== RTN_BROADCAST
||
270 (dev
->flags
& IFF_POINTOPOINT
)) {
271 neigh
->nud_state
= NUD_NOARP
;
272 memcpy(neigh
->ha
, dev
->broadcast
, dev
->addr_len
);
275 if (dev
->header_ops
->cache
)
276 neigh
->ops
= &arp_hh_ops
;
278 neigh
->ops
= &arp_generic_ops
;
280 if (neigh
->nud_state
& NUD_VALID
)
281 neigh
->output
= neigh
->ops
->connected_output
;
283 neigh
->output
= neigh
->ops
->output
;
288 static void arp_error_report(struct neighbour
*neigh
, struct sk_buff
*skb
)
290 dst_link_failure(skb
);
294 /* Create and send an arp packet. */
295 static void arp_send_dst(int type
, int ptype
, __be32 dest_ip
,
296 struct net_device
*dev
, __be32 src_ip
,
297 const unsigned char *dest_hw
,
298 const unsigned char *src_hw
,
299 const unsigned char *target_hw
, struct sk_buff
*oskb
)
303 /* arp on this interface. */
304 if (dev
->flags
& IFF_NOARP
)
307 skb
= arp_create(type
, ptype
, dest_ip
, dev
, src_ip
,
308 dest_hw
, src_hw
, target_hw
);
313 skb_dst_copy(skb
, oskb
);
318 void arp_send(int type
, int ptype
, __be32 dest_ip
,
319 struct net_device
*dev
, __be32 src_ip
,
320 const unsigned char *dest_hw
, const unsigned char *src_hw
,
321 const unsigned char *target_hw
)
323 arp_send_dst(type
, ptype
, dest_ip
, dev
, src_ip
, dest_hw
, src_hw
,
326 EXPORT_SYMBOL(arp_send
);
328 static void arp_solicit(struct neighbour
*neigh
, struct sk_buff
*skb
)
331 u8 dst_ha
[MAX_ADDR_LEN
], *dst_hw
= NULL
;
332 struct net_device
*dev
= neigh
->dev
;
333 __be32 target
= *(__be32
*)neigh
->primary_key
;
334 int probes
= atomic_read(&neigh
->probes
);
335 struct in_device
*in_dev
;
338 in_dev
= __in_dev_get_rcu(dev
);
343 switch (IN_DEV_ARP_ANNOUNCE(in_dev
)) {
345 case 0: /* By default announce any local IP */
346 if (skb
&& inet_addr_type_dev_table(dev_net(dev
), dev
,
347 ip_hdr(skb
)->saddr
) == RTN_LOCAL
)
348 saddr
= ip_hdr(skb
)->saddr
;
350 case 1: /* Restrict announcements of saddr in same subnet */
353 saddr
= ip_hdr(skb
)->saddr
;
354 if (inet_addr_type_dev_table(dev_net(dev
), dev
,
355 saddr
) == RTN_LOCAL
) {
356 /* saddr should be known to target */
357 if (inet_addr_onlink(in_dev
, target
, saddr
))
362 case 2: /* Avoid secondary IPs, get a primary/preferred one */
368 saddr
= inet_select_addr(dev
, target
, RT_SCOPE_LINK
);
370 probes
-= NEIGH_VAR(neigh
->parms
, UCAST_PROBES
);
372 if (!(neigh
->nud_state
& NUD_VALID
))
373 pr_debug("trying to ucast probe in NUD_INVALID\n");
374 neigh_ha_snapshot(dst_ha
, neigh
, dev
);
377 probes
-= NEIGH_VAR(neigh
->parms
, APP_PROBES
);
384 arp_send_dst(ARPOP_REQUEST
, ETH_P_ARP
, target
, dev
, saddr
,
385 dst_hw
, dev
->dev_addr
, NULL
,
386 dev
->priv_flags
& IFF_XMIT_DST_RELEASE
? NULL
: skb
);
389 static int arp_ignore(struct in_device
*in_dev
, __be32 sip
, __be32 tip
)
391 struct net
*net
= dev_net(in_dev
->dev
);
394 switch (IN_DEV_ARP_IGNORE(in_dev
)) {
395 case 0: /* Reply, the tip is already validated */
397 case 1: /* Reply only if tip is configured on the incoming interface */
399 scope
= RT_SCOPE_HOST
;
402 * Reply only if tip is configured on the incoming interface
403 * and is in same subnet as sip
405 scope
= RT_SCOPE_HOST
;
407 case 3: /* Do not reply for scope host addresses */
409 scope
= RT_SCOPE_LINK
;
412 case 4: /* Reserved */
417 case 8: /* Do not reply */
422 return !inet_confirm_addr(net
, in_dev
, sip
, tip
, scope
);
425 static int arp_filter(__be32 sip
, __be32 tip
, struct net_device
*dev
)
429 /*unsigned long now; */
430 struct net
*net
= dev_net(dev
);
432 rt
= ip_route_output(net
, sip
, tip
, 0, 0);
435 if (rt
->dst
.dev
!= dev
) {
436 NET_INC_STATS_BH(net
, LINUX_MIB_ARPFILTER
);
444 * Check if we can use proxy ARP for this path
446 static inline int arp_fwd_proxy(struct in_device
*in_dev
,
447 struct net_device
*dev
, struct rtable
*rt
)
449 struct in_device
*out_dev
;
452 if (rt
->dst
.dev
== dev
)
455 if (!IN_DEV_PROXY_ARP(in_dev
))
457 imi
= IN_DEV_MEDIUM_ID(in_dev
);
463 /* place to check for proxy_arp for routes */
465 out_dev
= __in_dev_get_rcu(rt
->dst
.dev
);
467 omi
= IN_DEV_MEDIUM_ID(out_dev
);
469 return omi
!= imi
&& omi
!= -1;
473 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
475 * RFC3069 supports proxy arp replies back to the same interface. This
476 * is done to support (ethernet) switch features, like RFC 3069, where
477 * the individual ports are not allowed to communicate with each
478 * other, BUT they are allowed to talk to the upstream router. As
479 * described in RFC 3069, it is possible to allow these hosts to
480 * communicate through the upstream router, by proxy_arp'ing.
482 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
484 * This technology is known by different names:
485 * In RFC 3069 it is called VLAN Aggregation.
486 * Cisco and Allied Telesyn call it Private VLAN.
487 * Hewlett-Packard call it Source-Port filtering or port-isolation.
488 * Ericsson call it MAC-Forced Forwarding (RFC Draft).
491 static inline int arp_fwd_pvlan(struct in_device
*in_dev
,
492 struct net_device
*dev
, struct rtable
*rt
,
493 __be32 sip
, __be32 tip
)
495 /* Private VLAN is only concerned about the same ethernet segment */
496 if (rt
->dst
.dev
!= dev
)
499 /* Don't reply on self probes (often done by windowz boxes)*/
503 if (IN_DEV_PROXY_ARP_PVLAN(in_dev
))
510 * Interface to link layer: send routine and receive handler.
514 * Create an arp packet. If dest_hw is not set, we create a broadcast
517 struct sk_buff
*arp_create(int type
, int ptype
, __be32 dest_ip
,
518 struct net_device
*dev
, __be32 src_ip
,
519 const unsigned char *dest_hw
,
520 const unsigned char *src_hw
,
521 const unsigned char *target_hw
)
525 unsigned char *arp_ptr
;
526 int hlen
= LL_RESERVED_SPACE(dev
);
527 int tlen
= dev
->needed_tailroom
;
533 skb
= alloc_skb(arp_hdr_len(dev
) + hlen
+ tlen
, GFP_ATOMIC
);
537 skb_reserve(skb
, hlen
);
538 skb_reset_network_header(skb
);
539 arp
= (struct arphdr
*) skb_put(skb
, arp_hdr_len(dev
));
541 skb
->protocol
= htons(ETH_P_ARP
);
543 src_hw
= dev
->dev_addr
;
545 dest_hw
= dev
->broadcast
;
548 * Fill the device header for the ARP frame
550 if (dev_hard_header(skb
, dev
, ptype
, dest_hw
, src_hw
, skb
->len
) < 0)
554 * Fill out the arp protocol part.
556 * The arp hardware type should match the device type, except for FDDI,
557 * which (according to RFC 1390) should always equal 1 (Ethernet).
560 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
561 * DIX code for the protocol. Make these device structure fields.
565 arp
->ar_hrd
= htons(dev
->type
);
566 arp
->ar_pro
= htons(ETH_P_IP
);
569 #if IS_ENABLED(CONFIG_AX25)
571 arp
->ar_hrd
= htons(ARPHRD_AX25
);
572 arp
->ar_pro
= htons(AX25_P_IP
);
575 #if IS_ENABLED(CONFIG_NETROM)
577 arp
->ar_hrd
= htons(ARPHRD_NETROM
);
578 arp
->ar_pro
= htons(AX25_P_IP
);
583 #if IS_ENABLED(CONFIG_FDDI)
585 arp
->ar_hrd
= htons(ARPHRD_ETHER
);
586 arp
->ar_pro
= htons(ETH_P_IP
);
591 arp
->ar_hln
= dev
->addr_len
;
593 arp
->ar_op
= htons(type
);
595 arp_ptr
= (unsigned char *)(arp
+ 1);
597 memcpy(arp_ptr
, src_hw
, dev
->addr_len
);
598 arp_ptr
+= dev
->addr_len
;
599 memcpy(arp_ptr
, &src_ip
, 4);
603 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
604 case ARPHRD_IEEE1394
:
609 memcpy(arp_ptr
, target_hw
, dev
->addr_len
);
611 memset(arp_ptr
, 0, dev
->addr_len
);
612 arp_ptr
+= dev
->addr_len
;
614 memcpy(arp_ptr
, &dest_ip
, 4);
622 EXPORT_SYMBOL(arp_create
);
625 * Send an arp packet.
627 void arp_xmit(struct sk_buff
*skb
)
629 /* Send it off, maybe filter it using firewalling first. */
630 NF_HOOK(NFPROTO_ARP
, NF_ARP_OUT
, NULL
, skb
,
631 NULL
, skb
->dev
, dev_queue_xmit_sk
);
633 EXPORT_SYMBOL(arp_xmit
);
636 * Process an arp request.
639 static int arp_process(struct sock
*sk
, struct sk_buff
*skb
)
641 struct net_device
*dev
= skb
->dev
;
642 struct in_device
*in_dev
= __in_dev_get_rcu(dev
);
644 unsigned char *arp_ptr
;
648 u16 dev_type
= dev
->type
;
651 struct net
*net
= dev_net(dev
);
652 bool is_garp
= false;
654 /* arp_rcv below verifies the ARP header and verifies the device
665 if (arp
->ar_pro
!= htons(ETH_P_IP
) ||
666 htons(dev_type
) != arp
->ar_hrd
)
673 * ETHERNET, and Fibre Channel (which are IEEE 802
674 * devices, according to RFC 2625) devices will accept ARP
675 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
676 * This is the case also of FDDI, where the RFC 1390 says that
677 * FDDI devices should accept ARP hardware of (1) Ethernet,
678 * however, to be more robust, we'll accept both 1 (Ethernet)
681 if ((arp
->ar_hrd
!= htons(ARPHRD_ETHER
) &&
682 arp
->ar_hrd
!= htons(ARPHRD_IEEE802
)) ||
683 arp
->ar_pro
!= htons(ETH_P_IP
))
687 if (arp
->ar_pro
!= htons(AX25_P_IP
) ||
688 arp
->ar_hrd
!= htons(ARPHRD_AX25
))
692 if (arp
->ar_pro
!= htons(AX25_P_IP
) ||
693 arp
->ar_hrd
!= htons(ARPHRD_NETROM
))
698 /* Understand only these message types */
700 if (arp
->ar_op
!= htons(ARPOP_REPLY
) &&
701 arp
->ar_op
!= htons(ARPOP_REQUEST
))
707 arp_ptr
= (unsigned char *)(arp
+ 1);
709 arp_ptr
+= dev
->addr_len
;
710 memcpy(&sip
, arp_ptr
, 4);
713 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
714 case ARPHRD_IEEE1394
:
718 arp_ptr
+= dev
->addr_len
;
720 memcpy(&tip
, arp_ptr
, 4);
722 * Check for bad requests for 127.x.x.x and requests for multicast
723 * addresses. If this is one such, delete it.
725 if (ipv4_is_multicast(tip
) ||
726 (!IN_DEV_ROUTE_LOCALNET(in_dev
) && ipv4_is_loopback(tip
)))
730 * Special case: We must set Frame Relay source Q.922 address
732 if (dev_type
== ARPHRD_DLCI
)
733 sha
= dev
->broadcast
;
736 * Process entry. The idea here is we want to send a reply if it is a
737 * request for us or if it is a request for someone else that we hold
738 * a proxy for. We want to add an entry to our cache if it is a reply
739 * to us or if it is a request for our address.
740 * (The assumption for this last is that if someone is requesting our
741 * address, they are probably intending to talk to us, so it saves time
742 * if we cache their address. Their address is also probably not in
743 * our cache, since ours is not in their cache.)
745 * Putting this another way, we only care about replies if they are to
746 * us, in which case we add them to the cache. For requests, we care
747 * about those for us and those for our proxies. We reply to both,
748 * and in the case of requests for us we add the requester to the arp
752 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
754 if (arp
->ar_op
== htons(ARPOP_REQUEST
) &&
755 inet_addr_type_dev_table(net
, dev
, tip
) == RTN_LOCAL
&&
756 !arp_ignore(in_dev
, sip
, tip
))
757 arp_send(ARPOP_REPLY
, ETH_P_ARP
, sip
, dev
, tip
, sha
,
762 if (arp
->ar_op
== htons(ARPOP_REQUEST
) &&
763 ip_route_input_noref(skb
, tip
, sip
, 0, dev
) == 0) {
765 rt
= skb_rtable(skb
);
766 addr_type
= rt
->rt_type
;
768 if (addr_type
== RTN_LOCAL
) {
771 dont_send
= arp_ignore(in_dev
, sip
, tip
);
772 if (!dont_send
&& IN_DEV_ARPFILTER(in_dev
))
773 dont_send
= arp_filter(sip
, tip
, dev
);
775 n
= neigh_event_ns(&arp_tbl
, sha
, &sip
, dev
);
777 arp_send(ARPOP_REPLY
, ETH_P_ARP
, sip
,
778 dev
, tip
, sha
, dev
->dev_addr
,
784 } else if (IN_DEV_FORWARD(in_dev
)) {
785 if (addr_type
== RTN_UNICAST
&&
786 (arp_fwd_proxy(in_dev
, dev
, rt
) ||
787 arp_fwd_pvlan(in_dev
, dev
, rt
, sip
, tip
) ||
788 (rt
->dst
.dev
!= dev
&&
789 pneigh_lookup(&arp_tbl
, net
, &tip
, dev
, 0)))) {
790 n
= neigh_event_ns(&arp_tbl
, sha
, &sip
, dev
);
794 if (NEIGH_CB(skb
)->flags
& LOCALLY_ENQUEUED
||
795 skb
->pkt_type
== PACKET_HOST
||
796 NEIGH_VAR(in_dev
->arp_parms
, PROXY_DELAY
) == 0) {
797 arp_send(ARPOP_REPLY
, ETH_P_ARP
, sip
,
798 dev
, tip
, sha
, dev
->dev_addr
,
801 pneigh_enqueue(&arp_tbl
,
802 in_dev
->arp_parms
, skb
);
810 /* Update our ARP tables */
812 n
= __neigh_lookup(&arp_tbl
, &sip
, dev
, 0);
814 if (IN_DEV_ARP_ACCEPT(in_dev
)) {
815 unsigned int addr_type
= inet_addr_type_dev_table(net
, dev
, sip
);
817 /* Unsolicited ARP is not accepted by default.
818 It is possible, that this option should be enabled for some
819 devices (strip is candidate)
821 is_garp
= arp
->ar_op
== htons(ARPOP_REQUEST
) && tip
== sip
&&
822 addr_type
== RTN_UNICAST
;
825 ((arp
->ar_op
== htons(ARPOP_REPLY
) &&
826 addr_type
== RTN_UNICAST
) || is_garp
))
827 n
= __neigh_lookup(&arp_tbl
, &sip
, dev
, 1);
831 int state
= NUD_REACHABLE
;
834 /* If several different ARP replies follows back-to-back,
835 use the FIRST one. It is possible, if several proxy
836 agents are active. Taking the first reply prevents
837 arp trashing and chooses the fastest router.
839 override
= time_after(jiffies
,
841 NEIGH_VAR(n
->parms
, LOCKTIME
)) ||
844 /* Broadcast replies and request packets
845 do not assert neighbour reachability.
847 if (arp
->ar_op
!= htons(ARPOP_REPLY
) ||
848 skb
->pkt_type
!= PACKET_HOST
)
850 neigh_update(n
, sha
, state
,
851 override
? NEIGH_UPDATE_F_OVERRIDE
: 0);
860 static void parp_redo(struct sk_buff
*skb
)
862 arp_process(NULL
, skb
);
867 * Receive an arp request from the device layer.
870 static int arp_rcv(struct sk_buff
*skb
, struct net_device
*dev
,
871 struct packet_type
*pt
, struct net_device
*orig_dev
)
873 const struct arphdr
*arp
;
875 /* do not tweak dropwatch on an ARP we will ignore */
876 if (dev
->flags
& IFF_NOARP
||
877 skb
->pkt_type
== PACKET_OTHERHOST
||
878 skb
->pkt_type
== PACKET_LOOPBACK
)
881 skb
= skb_share_check(skb
, GFP_ATOMIC
);
885 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
886 if (!pskb_may_pull(skb
, arp_hdr_len(dev
)))
890 if (arp
->ar_hln
!= dev
->addr_len
|| arp
->ar_pln
!= 4)
893 memset(NEIGH_CB(skb
), 0, sizeof(struct neighbour_cb
));
895 return NF_HOOK(NFPROTO_ARP
, NF_ARP_IN
, NULL
, skb
,
896 dev
, NULL
, arp_process
);
908 * User level interface (ioctl)
912 * Set (create) an ARP cache entry.
915 static int arp_req_set_proxy(struct net
*net
, struct net_device
*dev
, int on
)
918 IPV4_DEVCONF_ALL(net
, PROXY_ARP
) = on
;
921 if (__in_dev_get_rtnl(dev
)) {
922 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev
), PROXY_ARP
, on
);
928 static int arp_req_set_public(struct net
*net
, struct arpreq
*r
,
929 struct net_device
*dev
)
931 __be32 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
932 __be32 mask
= ((struct sockaddr_in
*)&r
->arp_netmask
)->sin_addr
.s_addr
;
934 if (mask
&& mask
!= htonl(0xFFFFFFFF))
936 if (!dev
&& (r
->arp_flags
& ATF_COM
)) {
937 dev
= dev_getbyhwaddr_rcu(net
, r
->arp_ha
.sa_family
,
943 if (!pneigh_lookup(&arp_tbl
, net
, &ip
, dev
, 1))
948 return arp_req_set_proxy(net
, dev
, 1);
951 static int arp_req_set(struct net
*net
, struct arpreq
*r
,
952 struct net_device
*dev
)
955 struct neighbour
*neigh
;
958 if (r
->arp_flags
& ATF_PUBL
)
959 return arp_req_set_public(net
, r
, dev
);
961 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
962 if (r
->arp_flags
& ATF_PERM
)
963 r
->arp_flags
|= ATF_COM
;
965 struct rtable
*rt
= ip_route_output(net
, ip
, 0, RTO_ONLINK
, 0);
975 #if IS_ENABLED(CONFIG_FDDI)
978 * According to RFC 1390, FDDI devices should accept ARP
979 * hardware types of 1 (Ethernet). However, to be more
980 * robust, we'll accept hardware types of either 1 (Ethernet)
983 if (r
->arp_ha
.sa_family
!= ARPHRD_FDDI
&&
984 r
->arp_ha
.sa_family
!= ARPHRD_ETHER
&&
985 r
->arp_ha
.sa_family
!= ARPHRD_IEEE802
)
990 if (r
->arp_ha
.sa_family
!= dev
->type
)
995 neigh
= __neigh_lookup_errno(&arp_tbl
, &ip
, dev
);
996 err
= PTR_ERR(neigh
);
997 if (!IS_ERR(neigh
)) {
998 unsigned int state
= NUD_STALE
;
999 if (r
->arp_flags
& ATF_PERM
)
1000 state
= NUD_PERMANENT
;
1001 err
= neigh_update(neigh
, (r
->arp_flags
& ATF_COM
) ?
1002 r
->arp_ha
.sa_data
: NULL
, state
,
1003 NEIGH_UPDATE_F_OVERRIDE
|
1004 NEIGH_UPDATE_F_ADMIN
);
1005 neigh_release(neigh
);
1010 static unsigned int arp_state_to_flags(struct neighbour
*neigh
)
1012 if (neigh
->nud_state
&NUD_PERMANENT
)
1013 return ATF_PERM
| ATF_COM
;
1014 else if (neigh
->nud_state
&NUD_VALID
)
1021 * Get an ARP cache entry.
1024 static int arp_req_get(struct arpreq
*r
, struct net_device
*dev
)
1026 __be32 ip
= ((struct sockaddr_in
*) &r
->arp_pa
)->sin_addr
.s_addr
;
1027 struct neighbour
*neigh
;
1030 neigh
= neigh_lookup(&arp_tbl
, &ip
, dev
);
1032 if (!(neigh
->nud_state
& NUD_NOARP
)) {
1033 read_lock_bh(&neigh
->lock
);
1034 memcpy(r
->arp_ha
.sa_data
, neigh
->ha
, dev
->addr_len
);
1035 r
->arp_flags
= arp_state_to_flags(neigh
);
1036 read_unlock_bh(&neigh
->lock
);
1037 r
->arp_ha
.sa_family
= dev
->type
;
1038 strlcpy(r
->arp_dev
, dev
->name
, sizeof(r
->arp_dev
));
1041 neigh_release(neigh
);
1046 static int arp_invalidate(struct net_device
*dev
, __be32 ip
)
1048 struct neighbour
*neigh
= neigh_lookup(&arp_tbl
, &ip
, dev
);
1052 if (neigh
->nud_state
& ~NUD_NOARP
)
1053 err
= neigh_update(neigh
, NULL
, NUD_FAILED
,
1054 NEIGH_UPDATE_F_OVERRIDE
|
1055 NEIGH_UPDATE_F_ADMIN
);
1056 neigh_release(neigh
);
1062 static int arp_req_delete_public(struct net
*net
, struct arpreq
*r
,
1063 struct net_device
*dev
)
1065 __be32 ip
= ((struct sockaddr_in
*) &r
->arp_pa
)->sin_addr
.s_addr
;
1066 __be32 mask
= ((struct sockaddr_in
*)&r
->arp_netmask
)->sin_addr
.s_addr
;
1068 if (mask
== htonl(0xFFFFFFFF))
1069 return pneigh_delete(&arp_tbl
, net
, &ip
, dev
);
1074 return arp_req_set_proxy(net
, dev
, 0);
1077 static int arp_req_delete(struct net
*net
, struct arpreq
*r
,
1078 struct net_device
*dev
)
1082 if (r
->arp_flags
& ATF_PUBL
)
1083 return arp_req_delete_public(net
, r
, dev
);
1085 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
1087 struct rtable
*rt
= ip_route_output(net
, ip
, 0, RTO_ONLINK
, 0);
1095 return arp_invalidate(dev
, ip
);
1099 * Handle an ARP layer I/O control request.
1102 int arp_ioctl(struct net
*net
, unsigned int cmd
, void __user
*arg
)
1106 struct net_device
*dev
= NULL
;
1111 if (!ns_capable(net
->user_ns
, CAP_NET_ADMIN
))
1114 err
= copy_from_user(&r
, arg
, sizeof(struct arpreq
));
1122 if (r
.arp_pa
.sa_family
!= AF_INET
)
1123 return -EPFNOSUPPORT
;
1125 if (!(r
.arp_flags
& ATF_PUBL
) &&
1126 (r
.arp_flags
& (ATF_NETMASK
| ATF_DONTPUB
)))
1128 if (!(r
.arp_flags
& ATF_NETMASK
))
1129 ((struct sockaddr_in
*)&r
.arp_netmask
)->sin_addr
.s_addr
=
1130 htonl(0xFFFFFFFFUL
);
1134 dev
= __dev_get_by_name(net
, r
.arp_dev
);
1138 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1139 if (!r
.arp_ha
.sa_family
)
1140 r
.arp_ha
.sa_family
= dev
->type
;
1142 if ((r
.arp_flags
& ATF_COM
) && r
.arp_ha
.sa_family
!= dev
->type
)
1144 } else if (cmd
== SIOCGARP
) {
1151 err
= arp_req_delete(net
, &r
, dev
);
1154 err
= arp_req_set(net
, &r
, dev
);
1157 err
= arp_req_get(&r
, dev
);
1162 if (cmd
== SIOCGARP
&& !err
&& copy_to_user(arg
, &r
, sizeof(r
)))
1167 static int arp_netdev_event(struct notifier_block
*this, unsigned long event
,
1170 struct net_device
*dev
= netdev_notifier_info_to_dev(ptr
);
1171 struct netdev_notifier_change_info
*change_info
;
1174 case NETDEV_CHANGEADDR
:
1175 neigh_changeaddr(&arp_tbl
, dev
);
1176 rt_cache_flush(dev_net(dev
));
1180 if (change_info
->flags_changed
& IFF_NOARP
)
1181 neigh_changeaddr(&arp_tbl
, dev
);
1190 static struct notifier_block arp_netdev_notifier
= {
1191 .notifier_call
= arp_netdev_event
,
1194 /* Note, that it is not on notifier chain.
1195 It is necessary, that this routine was called after route cache will be
1198 void arp_ifdown(struct net_device
*dev
)
1200 neigh_ifdown(&arp_tbl
, dev
);
1205 * Called once on startup.
1208 static struct packet_type arp_packet_type __read_mostly
= {
1209 .type
= cpu_to_be16(ETH_P_ARP
),
1213 static int arp_proc_init(void);
1215 void __init
arp_init(void)
1217 neigh_table_init(NEIGH_ARP_TABLE
, &arp_tbl
);
1219 dev_add_pack(&arp_packet_type
);
1221 #ifdef CONFIG_SYSCTL
1222 neigh_sysctl_register(NULL
, &arp_tbl
.parms
, NULL
);
1224 register_netdevice_notifier(&arp_netdev_notifier
);
1227 #ifdef CONFIG_PROC_FS
1228 #if IS_ENABLED(CONFIG_AX25)
1230 /* ------------------------------------------------------------------------ */
1232 * ax25 -> ASCII conversion
1234 static char *ax2asc2(ax25_address
*a
, char *buf
)
1239 for (n
= 0, s
= buf
; n
< 6; n
++) {
1240 c
= (a
->ax25_call
[n
] >> 1) & 0x7F;
1247 n
= (a
->ax25_call
[6] >> 1) & 0x0F;
1256 if (*buf
== '\0' || *buf
== '-')
1261 #endif /* CONFIG_AX25 */
1263 #define HBUFFERLEN 30
1265 static void arp_format_neigh_entry(struct seq_file
*seq
,
1266 struct neighbour
*n
)
1268 char hbuffer
[HBUFFERLEN
];
1271 struct net_device
*dev
= n
->dev
;
1272 int hatype
= dev
->type
;
1274 read_lock(&n
->lock
);
1275 /* Convert hardware address to XX:XX:XX:XX ... form. */
1276 #if IS_ENABLED(CONFIG_AX25)
1277 if (hatype
== ARPHRD_AX25
|| hatype
== ARPHRD_NETROM
)
1278 ax2asc2((ax25_address
*)n
->ha
, hbuffer
);
1281 for (k
= 0, j
= 0; k
< HBUFFERLEN
- 3 && j
< dev
->addr_len
; j
++) {
1282 hbuffer
[k
++] = hex_asc_hi(n
->ha
[j
]);
1283 hbuffer
[k
++] = hex_asc_lo(n
->ha
[j
]);
1289 #if IS_ENABLED(CONFIG_AX25)
1292 sprintf(tbuf
, "%pI4", n
->primary_key
);
1293 seq_printf(seq
, "%-16s 0x%-10x0x%-10x%s * %s\n",
1294 tbuf
, hatype
, arp_state_to_flags(n
), hbuffer
, dev
->name
);
1295 read_unlock(&n
->lock
);
1298 static void arp_format_pneigh_entry(struct seq_file
*seq
,
1299 struct pneigh_entry
*n
)
1301 struct net_device
*dev
= n
->dev
;
1302 int hatype
= dev
? dev
->type
: 0;
1305 sprintf(tbuf
, "%pI4", n
->key
);
1306 seq_printf(seq
, "%-16s 0x%-10x0x%-10x%s * %s\n",
1307 tbuf
, hatype
, ATF_PUBL
| ATF_PERM
, "00:00:00:00:00:00",
1308 dev
? dev
->name
: "*");
1311 static int arp_seq_show(struct seq_file
*seq
, void *v
)
1313 if (v
== SEQ_START_TOKEN
) {
1314 seq_puts(seq
, "IP address HW type Flags "
1315 "HW address Mask Device\n");
1317 struct neigh_seq_state
*state
= seq
->private;
1319 if (state
->flags
& NEIGH_SEQ_IS_PNEIGH
)
1320 arp_format_pneigh_entry(seq
, v
);
1322 arp_format_neigh_entry(seq
, v
);
1328 static void *arp_seq_start(struct seq_file
*seq
, loff_t
*pos
)
1330 /* Don't want to confuse "arp -a" w/ magic entries,
1331 * so we tell the generic iterator to skip NUD_NOARP.
1333 return neigh_seq_start(seq
, pos
, &arp_tbl
, NEIGH_SEQ_SKIP_NOARP
);
1336 /* ------------------------------------------------------------------------ */
1338 static const struct seq_operations arp_seq_ops
= {
1339 .start
= arp_seq_start
,
1340 .next
= neigh_seq_next
,
1341 .stop
= neigh_seq_stop
,
1342 .show
= arp_seq_show
,
1345 static int arp_seq_open(struct inode
*inode
, struct file
*file
)
1347 return seq_open_net(inode
, file
, &arp_seq_ops
,
1348 sizeof(struct neigh_seq_state
));
1351 static const struct file_operations arp_seq_fops
= {
1352 .owner
= THIS_MODULE
,
1353 .open
= arp_seq_open
,
1355 .llseek
= seq_lseek
,
1356 .release
= seq_release_net
,
1360 static int __net_init
arp_net_init(struct net
*net
)
1362 if (!proc_create("arp", S_IRUGO
, net
->proc_net
, &arp_seq_fops
))
1367 static void __net_exit
arp_net_exit(struct net
*net
)
1369 remove_proc_entry("arp", net
->proc_net
);
1372 static struct pernet_operations arp_net_ops
= {
1373 .init
= arp_net_init
,
1374 .exit
= arp_net_exit
,
1377 static int __init
arp_proc_init(void)
1379 return register_pernet_subsys(&arp_net_ops
);
1382 #else /* CONFIG_PROC_FS */
1384 static int __init
arp_proc_init(void)
1389 #endif /* CONFIG_PROC_FS */