1 /* linux/net/ipv4/arp.c
3 * Copyright (C) 1994 by Florian La Roche
5 * This module implements the Address Resolution Protocol ARP (RFC 826),
6 * which is used to convert IP addresses (or in the future maybe other
7 * high-level addresses) into a low-level hardware address (like an Ethernet
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version
13 * 2 of the License, or (at your option) any later version.
16 * Alan Cox : Removed the Ethernet assumptions in
18 * Alan Cox : Fixed some small errors in the ARP
20 * Alan Cox : Allow >4K in /proc
21 * Alan Cox : Make ARP add its own protocol entry
22 * Ross Martin : Rewrote arp_rcv() and arp_get_info()
23 * Stephen Henson : Add AX25 support to arp_get_info()
24 * Alan Cox : Drop data when a device is downed.
25 * Alan Cox : Use init_timer().
26 * Alan Cox : Double lock fixes.
27 * Martin Seine : Move the arphdr structure
28 * to if_arp.h for compatibility.
29 * with BSD based programs.
30 * Andrew Tridgell : Added ARP netmask code and
31 * re-arranged proxy handling.
32 * Alan Cox : Changed to use notifiers.
33 * Niibe Yutaka : Reply for this device or proxies only.
34 * Alan Cox : Don't proxy across hardware types!
35 * Jonathan Naylor : Added support for NET/ROM.
36 * Mike Shaver : RFC1122 checks.
37 * Jonathan Naylor : Only lookup the hardware address for
38 * the correct hardware type.
39 * Germano Caronni : Assorted subtle races.
40 * Craig Schlenter : Don't modify permanent entry
42 * Russ Nelson : Tidied up a few bits.
43 * Alexey Kuznetsov: Major changes to caching and behaviour,
44 * eg intelligent arp probing and
46 * of host down events.
47 * Alan Cox : Missing unlock in device events.
48 * Eckes : ARP ioctl control errors.
49 * Alexey Kuznetsov: Arp free fix.
50 * Manuel Rodriguez: Gratuitous ARP.
51 * Jonathan Layes : Added arpd support through kerneld
52 * message queue (960314)
53 * Mike Shaver : /proc/sys/net/ipv4/arp_* support
54 * Mike McLagan : Routing by source
55 * Stuart Cheshire : Metricom and grat arp fixes
56 * *** FOR 2.1 clean this up ***
57 * Lawrence V. Stefani: (08/12/96) Added FDDI support.
58 * Alan Cox : Took the AP1000 nasty FDDI hack and
59 * folded into the mainstream FDDI code.
60 * Ack spit, Linus how did you allow that
62 * Jes Sorensen : Make FDDI work again in 2.1.x and
63 * clean up the APFDDI & gen. FDDI bits.
64 * Alexey Kuznetsov: new arp state machine;
65 * now it is in net/core/neighbour.c.
66 * Krzysztof Halasa: Added Frame Relay ARP support.
67 * Arnaldo C. Melo : convert /proc/net/arp to seq_file
68 * Shmulik Hen: Split arp_send to arp_create and
69 * arp_xmit so intermediate drivers like
70 * bonding can change the skb before
71 * sending (e.g. insert 8021q tag).
72 * Harald Welte : convert to make use of jenkins hash
73 * Jesper D. Brouer: Proxy ARP PVLAN RFC 3069 support.
76 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
78 #include <linux/module.h>
79 #include <linux/types.h>
80 #include <linux/string.h>
81 #include <linux/kernel.h>
82 #include <linux/capability.h>
83 #include <linux/socket.h>
84 #include <linux/sockios.h>
85 #include <linux/errno.h>
88 #include <linux/inet.h>
89 #include <linux/inetdevice.h>
90 #include <linux/netdevice.h>
91 #include <linux/etherdevice.h>
92 #include <linux/fddidevice.h>
93 #include <linux/if_arp.h>
94 #include <linux/skbuff.h>
95 #include <linux/proc_fs.h>
96 #include <linux/seq_file.h>
97 #include <linux/stat.h>
98 #include <linux/init.h>
99 #include <linux/net.h>
100 #include <linux/rcupdate.h>
101 #include <linux/slab.h>
103 #include <linux/sysctl.h>
106 #include <net/net_namespace.h>
108 #include <net/icmp.h>
109 #include <net/route.h>
110 #include <net/protocol.h>
112 #include <net/sock.h>
114 #include <net/ax25.h>
115 #include <net/netrom.h>
117 #include <linux/uaccess.h>
119 #include <linux/netfilter_arp.h>
122 * Interface to generic neighbour cache.
124 static u32
arp_hash(const void *pkey
, const struct net_device
*dev
, __u32
*hash_rnd
);
125 static int arp_constructor(struct neighbour
*neigh
);
126 static void arp_solicit(struct neighbour
*neigh
, struct sk_buff
*skb
);
127 static void arp_error_report(struct neighbour
*neigh
, struct sk_buff
*skb
);
128 static void parp_redo(struct sk_buff
*skb
);
130 static const struct neigh_ops arp_generic_ops
= {
132 .solicit
= arp_solicit
,
133 .error_report
= arp_error_report
,
134 .output
= neigh_resolve_output
,
135 .connected_output
= neigh_connected_output
,
138 static const struct neigh_ops arp_hh_ops
= {
140 .solicit
= arp_solicit
,
141 .error_report
= arp_error_report
,
142 .output
= neigh_resolve_output
,
143 .connected_output
= neigh_resolve_output
,
146 static const struct neigh_ops arp_direct_ops
= {
148 .output
= neigh_direct_output
,
149 .connected_output
= neigh_direct_output
,
152 static const struct neigh_ops arp_broken_ops
= {
154 .solicit
= arp_solicit
,
155 .error_report
= arp_error_report
,
156 .output
= neigh_compat_output
,
157 .connected_output
= neigh_compat_output
,
160 struct neigh_table arp_tbl
= {
164 .constructor
= arp_constructor
,
165 .proxy_redo
= parp_redo
,
169 .base_reachable_time
= 30 * HZ
,
170 .retrans_time
= 1 * HZ
,
171 .gc_staletime
= 60 * HZ
,
172 .reachable_time
= 30 * HZ
,
173 .delay_probe_time
= 5 * HZ
,
174 .queue_len_bytes
= 64*1024,
177 .anycast_delay
= 1 * HZ
,
178 .proxy_delay
= (8 * HZ
) / 10,
182 .gc_interval
= 30 * HZ
,
187 EXPORT_SYMBOL(arp_tbl
);
189 int arp_mc_map(__be32 addr
, u8
*haddr
, struct net_device
*dev
, int dir
)
195 ip_eth_mc_map(addr
, haddr
);
197 case ARPHRD_INFINIBAND
:
198 ip_ib_mc_map(addr
, dev
->broadcast
, haddr
);
201 ip_ipgre_mc_map(addr
, dev
->broadcast
, haddr
);
205 memcpy(haddr
, dev
->broadcast
, dev
->addr_len
);
213 static u32
arp_hash(const void *pkey
,
214 const struct net_device
*dev
,
217 return arp_hashfn(*(u32
*)pkey
, dev
, *hash_rnd
);
220 static int arp_constructor(struct neighbour
*neigh
)
222 __be32 addr
= *(__be32
*)neigh
->primary_key
;
223 struct net_device
*dev
= neigh
->dev
;
224 struct in_device
*in_dev
;
225 struct neigh_parms
*parms
;
228 in_dev
= __in_dev_get_rcu(dev
);
229 if (in_dev
== NULL
) {
234 neigh
->type
= inet_addr_type(dev_net(dev
), addr
);
236 parms
= in_dev
->arp_parms
;
237 __neigh_parms_put(neigh
->parms
);
238 neigh
->parms
= neigh_parms_clone(parms
);
241 if (!dev
->header_ops
) {
242 neigh
->nud_state
= NUD_NOARP
;
243 neigh
->ops
= &arp_direct_ops
;
244 neigh
->output
= neigh_direct_output
;
246 /* Good devices (checked by reading texts, but only Ethernet is
249 ARPHRD_ETHER: (ethernet, apfddi)
252 ARPHRD_METRICOM: (strip)
256 ARPHRD_IPDDP will also work, if author repairs it.
257 I did not it, because this driver does not work even
262 /* So... these "amateur" devices are hopeless.
263 The only thing, that I can say now:
264 It is very sad that we need to keep ugly obsolete
265 code to make them happy.
267 They should be moved to more reasonable state, now
268 they use rebuild_header INSTEAD OF hard_start_xmit!!!
269 Besides that, they are sort of out of date
270 (a lot of redundant clones/copies, useless in 2.1),
271 I wonder why people believe that they work.
277 #if IS_ENABLED(CONFIG_AX25)
279 #if IS_ENABLED(CONFIG_NETROM)
282 neigh
->ops
= &arp_broken_ops
;
283 neigh
->output
= neigh
->ops
->output
;
290 if (neigh
->type
== RTN_MULTICAST
) {
291 neigh
->nud_state
= NUD_NOARP
;
292 arp_mc_map(addr
, neigh
->ha
, dev
, 1);
293 } else if (dev
->flags
& (IFF_NOARP
| IFF_LOOPBACK
)) {
294 neigh
->nud_state
= NUD_NOARP
;
295 memcpy(neigh
->ha
, dev
->dev_addr
, dev
->addr_len
);
296 } else if (neigh
->type
== RTN_BROADCAST
||
297 (dev
->flags
& IFF_POINTOPOINT
)) {
298 neigh
->nud_state
= NUD_NOARP
;
299 memcpy(neigh
->ha
, dev
->broadcast
, dev
->addr_len
);
302 if (dev
->header_ops
->cache
)
303 neigh
->ops
= &arp_hh_ops
;
305 neigh
->ops
= &arp_generic_ops
;
307 if (neigh
->nud_state
& NUD_VALID
)
308 neigh
->output
= neigh
->ops
->connected_output
;
310 neigh
->output
= neigh
->ops
->output
;
315 static void arp_error_report(struct neighbour
*neigh
, struct sk_buff
*skb
)
317 dst_link_failure(skb
);
321 static void arp_solicit(struct neighbour
*neigh
, struct sk_buff
*skb
)
325 struct net_device
*dev
= neigh
->dev
;
326 __be32 target
= *(__be32
*)neigh
->primary_key
;
327 int probes
= atomic_read(&neigh
->probes
);
328 struct in_device
*in_dev
;
331 in_dev
= __in_dev_get_rcu(dev
);
336 switch (IN_DEV_ARP_ANNOUNCE(in_dev
)) {
338 case 0: /* By default announce any local IP */
339 if (skb
&& inet_addr_type(dev_net(dev
),
340 ip_hdr(skb
)->saddr
) == RTN_LOCAL
)
341 saddr
= ip_hdr(skb
)->saddr
;
343 case 1: /* Restrict announcements of saddr in same subnet */
346 saddr
= ip_hdr(skb
)->saddr
;
347 if (inet_addr_type(dev_net(dev
), saddr
) == RTN_LOCAL
) {
348 /* saddr should be known to target */
349 if (inet_addr_onlink(in_dev
, target
, saddr
))
354 case 2: /* Avoid secondary IPs, get a primary/preferred one */
360 saddr
= inet_select_addr(dev
, target
, RT_SCOPE_LINK
);
362 probes
-= neigh
->parms
->ucast_probes
;
364 if (!(neigh
->nud_state
& NUD_VALID
))
365 pr_debug("trying to ucast probe in NUD_INVALID\n");
367 read_lock_bh(&neigh
->lock
);
369 probes
-= neigh
->parms
->app_probes
;
378 arp_send(ARPOP_REQUEST
, ETH_P_ARP
, target
, dev
, saddr
,
379 dst_ha
, dev
->dev_addr
, NULL
);
381 read_unlock_bh(&neigh
->lock
);
384 static int arp_ignore(struct in_device
*in_dev
, __be32 sip
, __be32 tip
)
388 switch (IN_DEV_ARP_IGNORE(in_dev
)) {
389 case 0: /* Reply, the tip is already validated */
391 case 1: /* Reply only if tip is configured on the incoming interface */
393 scope
= RT_SCOPE_HOST
;
396 * Reply only if tip is configured on the incoming interface
397 * and is in same subnet as sip
399 scope
= RT_SCOPE_HOST
;
401 case 3: /* Do not reply for scope host addresses */
403 scope
= RT_SCOPE_LINK
;
405 case 4: /* Reserved */
410 case 8: /* Do not reply */
415 return !inet_confirm_addr(in_dev
, sip
, tip
, scope
);
418 static int arp_filter(__be32 sip
, __be32 tip
, struct net_device
*dev
)
422 /*unsigned long now; */
423 struct net
*net
= dev_net(dev
);
425 rt
= ip_route_output(net
, sip
, tip
, 0, 0);
428 if (rt
->dst
.dev
!= dev
) {
429 NET_INC_STATS_BH(net
, LINUX_MIB_ARPFILTER
);
436 /* OBSOLETE FUNCTIONS */
439 * Find an arp mapping in the cache. If not found, post a request.
441 * It is very UGLY routine: it DOES NOT use skb->dst->neighbour,
442 * even if it exists. It is supposed that skb->dev was mangled
443 * by a virtual device (eql, shaper). Nobody but broken devices
444 * is allowed to use this function, it is scheduled to be removed. --ANK
447 static int arp_set_predefined(int addr_hint
, unsigned char *haddr
,
448 __be32 paddr
, struct net_device
*dev
)
452 pr_debug("arp called for own IP address\n");
453 memcpy(haddr
, dev
->dev_addr
, dev
->addr_len
);
456 arp_mc_map(paddr
, haddr
, dev
, 1);
459 memcpy(haddr
, dev
->broadcast
, dev
->addr_len
);
466 int arp_find(unsigned char *haddr
, struct sk_buff
*skb
)
468 struct net_device
*dev
= skb
->dev
;
473 pr_debug("arp_find is called with dst==NULL\n");
478 paddr
= skb_rtable(skb
)->rt_gateway
;
480 if (arp_set_predefined(inet_addr_type(dev_net(dev
), paddr
), haddr
,
484 n
= __neigh_lookup(&arp_tbl
, &paddr
, dev
, 1);
488 if (n
->nud_state
& NUD_VALID
|| neigh_event_send(n
, skb
) == 0) {
489 neigh_ha_snapshot(haddr
, n
, dev
);
498 EXPORT_SYMBOL(arp_find
);
500 /* END OF OBSOLETE FUNCTIONS */
503 * Check if we can use proxy ARP for this path
505 static inline int arp_fwd_proxy(struct in_device
*in_dev
,
506 struct net_device
*dev
, struct rtable
*rt
)
508 struct in_device
*out_dev
;
511 if (rt
->dst
.dev
== dev
)
514 if (!IN_DEV_PROXY_ARP(in_dev
))
516 imi
= IN_DEV_MEDIUM_ID(in_dev
);
522 /* place to check for proxy_arp for routes */
524 out_dev
= __in_dev_get_rcu(rt
->dst
.dev
);
526 omi
= IN_DEV_MEDIUM_ID(out_dev
);
528 return omi
!= imi
&& omi
!= -1;
532 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
534 * RFC3069 supports proxy arp replies back to the same interface. This
535 * is done to support (ethernet) switch features, like RFC 3069, where
536 * the individual ports are not allowed to communicate with each
537 * other, BUT they are allowed to talk to the upstream router. As
538 * described in RFC 3069, it is possible to allow these hosts to
539 * communicate through the upstream router, by proxy_arp'ing.
541 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
543 * This technology is known by different names:
544 * In RFC 3069 it is called VLAN Aggregation.
545 * Cisco and Allied Telesyn call it Private VLAN.
546 * Hewlett-Packard call it Source-Port filtering or port-isolation.
547 * Ericsson call it MAC-Forced Forwarding (RFC Draft).
550 static inline int arp_fwd_pvlan(struct in_device
*in_dev
,
551 struct net_device
*dev
, struct rtable
*rt
,
552 __be32 sip
, __be32 tip
)
554 /* Private VLAN is only concerned about the same ethernet segment */
555 if (rt
->dst
.dev
!= dev
)
558 /* Don't reply on self probes (often done by windowz boxes)*/
562 if (IN_DEV_PROXY_ARP_PVLAN(in_dev
))
569 * Interface to link layer: send routine and receive handler.
573 * Create an arp packet. If (dest_hw == NULL), we create a broadcast
576 struct sk_buff
*arp_create(int type
, int ptype
, __be32 dest_ip
,
577 struct net_device
*dev
, __be32 src_ip
,
578 const unsigned char *dest_hw
,
579 const unsigned char *src_hw
,
580 const unsigned char *target_hw
)
584 unsigned char *arp_ptr
;
585 int hlen
= LL_RESERVED_SPACE(dev
);
586 int tlen
= dev
->needed_tailroom
;
592 skb
= alloc_skb(arp_hdr_len(dev
) + hlen
+ tlen
, GFP_ATOMIC
);
596 skb_reserve(skb
, hlen
);
597 skb_reset_network_header(skb
);
598 arp
= (struct arphdr
*) skb_put(skb
, arp_hdr_len(dev
));
600 skb
->protocol
= htons(ETH_P_ARP
);
602 src_hw
= dev
->dev_addr
;
604 dest_hw
= dev
->broadcast
;
607 * Fill the device header for the ARP frame
609 if (dev_hard_header(skb
, dev
, ptype
, dest_hw
, src_hw
, skb
->len
) < 0)
613 * Fill out the arp protocol part.
615 * The arp hardware type should match the device type, except for FDDI,
616 * which (according to RFC 1390) should always equal 1 (Ethernet).
619 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
620 * DIX code for the protocol. Make these device structure fields.
624 arp
->ar_hrd
= htons(dev
->type
);
625 arp
->ar_pro
= htons(ETH_P_IP
);
628 #if IS_ENABLED(CONFIG_AX25)
630 arp
->ar_hrd
= htons(ARPHRD_AX25
);
631 arp
->ar_pro
= htons(AX25_P_IP
);
634 #if IS_ENABLED(CONFIG_NETROM)
636 arp
->ar_hrd
= htons(ARPHRD_NETROM
);
637 arp
->ar_pro
= htons(AX25_P_IP
);
642 #if IS_ENABLED(CONFIG_FDDI)
644 arp
->ar_hrd
= htons(ARPHRD_ETHER
);
645 arp
->ar_pro
= htons(ETH_P_IP
);
650 arp
->ar_hln
= dev
->addr_len
;
652 arp
->ar_op
= htons(type
);
654 arp_ptr
= (unsigned char *)(arp
+ 1);
656 memcpy(arp_ptr
, src_hw
, dev
->addr_len
);
657 arp_ptr
+= dev
->addr_len
;
658 memcpy(arp_ptr
, &src_ip
, 4);
660 if (target_hw
!= NULL
)
661 memcpy(arp_ptr
, target_hw
, dev
->addr_len
);
663 memset(arp_ptr
, 0, dev
->addr_len
);
664 arp_ptr
+= dev
->addr_len
;
665 memcpy(arp_ptr
, &dest_ip
, 4);
673 EXPORT_SYMBOL(arp_create
);
676 * Send an arp packet.
678 void arp_xmit(struct sk_buff
*skb
)
680 /* Send it off, maybe filter it using firewalling first. */
681 NF_HOOK(NFPROTO_ARP
, NF_ARP_OUT
, skb
, NULL
, skb
->dev
, dev_queue_xmit
);
683 EXPORT_SYMBOL(arp_xmit
);
686 * Create and send an arp packet.
688 void arp_send(int type
, int ptype
, __be32 dest_ip
,
689 struct net_device
*dev
, __be32 src_ip
,
690 const unsigned char *dest_hw
, const unsigned char *src_hw
,
691 const unsigned char *target_hw
)
696 * No arp on this interface.
699 if (dev
->flags
&IFF_NOARP
)
702 skb
= arp_create(type
, ptype
, dest_ip
, dev
, src_ip
,
703 dest_hw
, src_hw
, target_hw
);
709 EXPORT_SYMBOL(arp_send
);
712 * Process an arp request.
715 static int arp_process(struct sk_buff
*skb
)
717 struct net_device
*dev
= skb
->dev
;
718 struct in_device
*in_dev
= __in_dev_get_rcu(dev
);
720 unsigned char *arp_ptr
;
724 u16 dev_type
= dev
->type
;
727 struct net
*net
= dev_net(dev
);
729 /* arp_rcv below verifies the ARP header and verifies the device
740 if (arp
->ar_pro
!= htons(ETH_P_IP
) ||
741 htons(dev_type
) != arp
->ar_hrd
)
748 * ETHERNET, and Fibre Channel (which are IEEE 802
749 * devices, according to RFC 2625) devices will accept ARP
750 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
751 * This is the case also of FDDI, where the RFC 1390 says that
752 * FDDI devices should accept ARP hardware of (1) Ethernet,
753 * however, to be more robust, we'll accept both 1 (Ethernet)
756 if ((arp
->ar_hrd
!= htons(ARPHRD_ETHER
) &&
757 arp
->ar_hrd
!= htons(ARPHRD_IEEE802
)) ||
758 arp
->ar_pro
!= htons(ETH_P_IP
))
762 if (arp
->ar_pro
!= htons(AX25_P_IP
) ||
763 arp
->ar_hrd
!= htons(ARPHRD_AX25
))
767 if (arp
->ar_pro
!= htons(AX25_P_IP
) ||
768 arp
->ar_hrd
!= htons(ARPHRD_NETROM
))
773 /* Understand only these message types */
775 if (arp
->ar_op
!= htons(ARPOP_REPLY
) &&
776 arp
->ar_op
!= htons(ARPOP_REQUEST
))
782 arp_ptr
= (unsigned char *)(arp
+ 1);
784 arp_ptr
+= dev
->addr_len
;
785 memcpy(&sip
, arp_ptr
, 4);
787 arp_ptr
+= dev
->addr_len
;
788 memcpy(&tip
, arp_ptr
, 4);
790 * Check for bad requests for 127.x.x.x and requests for multicast
791 * addresses. If this is one such, delete it.
793 if (ipv4_is_multicast(tip
) ||
794 (!IN_DEV_ROUTE_LOCALNET(in_dev
) && ipv4_is_loopback(tip
)))
798 * Special case: We must set Frame Relay source Q.922 address
800 if (dev_type
== ARPHRD_DLCI
)
801 sha
= dev
->broadcast
;
804 * Process entry. The idea here is we want to send a reply if it is a
805 * request for us or if it is a request for someone else that we hold
806 * a proxy for. We want to add an entry to our cache if it is a reply
807 * to us or if it is a request for our address.
808 * (The assumption for this last is that if someone is requesting our
809 * address, they are probably intending to talk to us, so it saves time
810 * if we cache their address. Their address is also probably not in
811 * our cache, since ours is not in their cache.)
813 * Putting this another way, we only care about replies if they are to
814 * us, in which case we add them to the cache. For requests, we care
815 * about those for us and those for our proxies. We reply to both,
816 * and in the case of requests for us we add the requester to the arp
820 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
822 if (arp
->ar_op
== htons(ARPOP_REQUEST
) &&
823 inet_addr_type(net
, tip
) == RTN_LOCAL
&&
824 !arp_ignore(in_dev
, sip
, tip
))
825 arp_send(ARPOP_REPLY
, ETH_P_ARP
, sip
, dev
, tip
, sha
,
830 if (arp
->ar_op
== htons(ARPOP_REQUEST
) &&
831 ip_route_input_noref(skb
, tip
, sip
, 0, dev
) == 0) {
833 rt
= skb_rtable(skb
);
834 addr_type
= rt
->rt_type
;
836 if (addr_type
== RTN_LOCAL
) {
839 dont_send
= arp_ignore(in_dev
, sip
, tip
);
840 if (!dont_send
&& IN_DEV_ARPFILTER(in_dev
))
841 dont_send
= arp_filter(sip
, tip
, dev
);
843 n
= neigh_event_ns(&arp_tbl
, sha
, &sip
, dev
);
845 arp_send(ARPOP_REPLY
, ETH_P_ARP
, sip
,
846 dev
, tip
, sha
, dev
->dev_addr
,
852 } else if (IN_DEV_FORWARD(in_dev
)) {
853 if (addr_type
== RTN_UNICAST
&&
854 (arp_fwd_proxy(in_dev
, dev
, rt
) ||
855 arp_fwd_pvlan(in_dev
, dev
, rt
, sip
, tip
) ||
856 (rt
->dst
.dev
!= dev
&&
857 pneigh_lookup(&arp_tbl
, net
, &tip
, dev
, 0)))) {
858 n
= neigh_event_ns(&arp_tbl
, sha
, &sip
, dev
);
862 if (NEIGH_CB(skb
)->flags
& LOCALLY_ENQUEUED
||
863 skb
->pkt_type
== PACKET_HOST
||
864 in_dev
->arp_parms
->proxy_delay
== 0) {
865 arp_send(ARPOP_REPLY
, ETH_P_ARP
, sip
,
866 dev
, tip
, sha
, dev
->dev_addr
,
869 pneigh_enqueue(&arp_tbl
,
870 in_dev
->arp_parms
, skb
);
878 /* Update our ARP tables */
880 n
= __neigh_lookup(&arp_tbl
, &sip
, dev
, 0);
882 if (IN_DEV_ARP_ACCEPT(in_dev
)) {
883 /* Unsolicited ARP is not accepted by default.
884 It is possible, that this option should be enabled for some
885 devices (strip is candidate)
888 (arp
->ar_op
== htons(ARPOP_REPLY
) ||
889 (arp
->ar_op
== htons(ARPOP_REQUEST
) && tip
== sip
)) &&
890 inet_addr_type(net
, sip
) == RTN_UNICAST
)
891 n
= __neigh_lookup(&arp_tbl
, &sip
, dev
, 1);
895 int state
= NUD_REACHABLE
;
898 /* If several different ARP replies follows back-to-back,
899 use the FIRST one. It is possible, if several proxy
900 agents are active. Taking the first reply prevents
901 arp trashing and chooses the fastest router.
903 override
= time_after(jiffies
, n
->updated
+ n
->parms
->locktime
);
905 /* Broadcast replies and request packets
906 do not assert neighbour reachability.
908 if (arp
->ar_op
!= htons(ARPOP_REPLY
) ||
909 skb
->pkt_type
!= PACKET_HOST
)
911 neigh_update(n
, sha
, state
,
912 override
? NEIGH_UPDATE_F_OVERRIDE
: 0);
921 static void parp_redo(struct sk_buff
*skb
)
928 * Receive an arp request from the device layer.
931 static int arp_rcv(struct sk_buff
*skb
, struct net_device
*dev
,
932 struct packet_type
*pt
, struct net_device
*orig_dev
)
936 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
937 if (!pskb_may_pull(skb
, arp_hdr_len(dev
)))
941 if (arp
->ar_hln
!= dev
->addr_len
||
942 dev
->flags
& IFF_NOARP
||
943 skb
->pkt_type
== PACKET_OTHERHOST
||
944 skb
->pkt_type
== PACKET_LOOPBACK
||
948 skb
= skb_share_check(skb
, GFP_ATOMIC
);
952 memset(NEIGH_CB(skb
), 0, sizeof(struct neighbour_cb
));
954 return NF_HOOK(NFPROTO_ARP
, NF_ARP_IN
, skb
, dev
, NULL
, arp_process
);
963 * User level interface (ioctl)
967 * Set (create) an ARP cache entry.
970 static int arp_req_set_proxy(struct net
*net
, struct net_device
*dev
, int on
)
973 IPV4_DEVCONF_ALL(net
, PROXY_ARP
) = on
;
976 if (__in_dev_get_rtnl(dev
)) {
977 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev
), PROXY_ARP
, on
);
983 static int arp_req_set_public(struct net
*net
, struct arpreq
*r
,
984 struct net_device
*dev
)
986 __be32 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
987 __be32 mask
= ((struct sockaddr_in
*)&r
->arp_netmask
)->sin_addr
.s_addr
;
989 if (mask
&& mask
!= htonl(0xFFFFFFFF))
991 if (!dev
&& (r
->arp_flags
& ATF_COM
)) {
992 dev
= dev_getbyhwaddr_rcu(net
, r
->arp_ha
.sa_family
,
998 if (pneigh_lookup(&arp_tbl
, net
, &ip
, dev
, 1) == NULL
)
1003 return arp_req_set_proxy(net
, dev
, 1);
1006 static int arp_req_set(struct net
*net
, struct arpreq
*r
,
1007 struct net_device
*dev
)
1010 struct neighbour
*neigh
;
1013 if (r
->arp_flags
& ATF_PUBL
)
1014 return arp_req_set_public(net
, r
, dev
);
1016 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
1017 if (r
->arp_flags
& ATF_PERM
)
1018 r
->arp_flags
|= ATF_COM
;
1020 struct rtable
*rt
= ip_route_output(net
, ip
, 0, RTO_ONLINK
, 0);
1029 switch (dev
->type
) {
1030 #if IS_ENABLED(CONFIG_FDDI)
1033 * According to RFC 1390, FDDI devices should accept ARP
1034 * hardware types of 1 (Ethernet). However, to be more
1035 * robust, we'll accept hardware types of either 1 (Ethernet)
1036 * or 6 (IEEE 802.2).
1038 if (r
->arp_ha
.sa_family
!= ARPHRD_FDDI
&&
1039 r
->arp_ha
.sa_family
!= ARPHRD_ETHER
&&
1040 r
->arp_ha
.sa_family
!= ARPHRD_IEEE802
)
1045 if (r
->arp_ha
.sa_family
!= dev
->type
)
1050 neigh
= __neigh_lookup_errno(&arp_tbl
, &ip
, dev
);
1051 err
= PTR_ERR(neigh
);
1052 if (!IS_ERR(neigh
)) {
1053 unsigned int state
= NUD_STALE
;
1054 if (r
->arp_flags
& ATF_PERM
)
1055 state
= NUD_PERMANENT
;
1056 err
= neigh_update(neigh
, (r
->arp_flags
& ATF_COM
) ?
1057 r
->arp_ha
.sa_data
: NULL
, state
,
1058 NEIGH_UPDATE_F_OVERRIDE
|
1059 NEIGH_UPDATE_F_ADMIN
);
1060 neigh_release(neigh
);
1065 static unsigned int arp_state_to_flags(struct neighbour
*neigh
)
1067 if (neigh
->nud_state
&NUD_PERMANENT
)
1068 return ATF_PERM
| ATF_COM
;
1069 else if (neigh
->nud_state
&NUD_VALID
)
1076 * Get an ARP cache entry.
1079 static int arp_req_get(struct arpreq
*r
, struct net_device
*dev
)
1081 __be32 ip
= ((struct sockaddr_in
*) &r
->arp_pa
)->sin_addr
.s_addr
;
1082 struct neighbour
*neigh
;
1085 neigh
= neigh_lookup(&arp_tbl
, &ip
, dev
);
1087 read_lock_bh(&neigh
->lock
);
1088 memcpy(r
->arp_ha
.sa_data
, neigh
->ha
, dev
->addr_len
);
1089 r
->arp_flags
= arp_state_to_flags(neigh
);
1090 read_unlock_bh(&neigh
->lock
);
1091 r
->arp_ha
.sa_family
= dev
->type
;
1092 strlcpy(r
->arp_dev
, dev
->name
, sizeof(r
->arp_dev
));
1093 neigh_release(neigh
);
1099 int arp_invalidate(struct net_device
*dev
, __be32 ip
)
1101 struct neighbour
*neigh
= neigh_lookup(&arp_tbl
, &ip
, dev
);
1105 if (neigh
->nud_state
& ~NUD_NOARP
)
1106 err
= neigh_update(neigh
, NULL
, NUD_FAILED
,
1107 NEIGH_UPDATE_F_OVERRIDE
|
1108 NEIGH_UPDATE_F_ADMIN
);
1109 neigh_release(neigh
);
1114 EXPORT_SYMBOL(arp_invalidate
);
1116 static int arp_req_delete_public(struct net
*net
, struct arpreq
*r
,
1117 struct net_device
*dev
)
1119 __be32 ip
= ((struct sockaddr_in
*) &r
->arp_pa
)->sin_addr
.s_addr
;
1120 __be32 mask
= ((struct sockaddr_in
*)&r
->arp_netmask
)->sin_addr
.s_addr
;
1122 if (mask
== htonl(0xFFFFFFFF))
1123 return pneigh_delete(&arp_tbl
, net
, &ip
, dev
);
1128 return arp_req_set_proxy(net
, dev
, 0);
1131 static int arp_req_delete(struct net
*net
, struct arpreq
*r
,
1132 struct net_device
*dev
)
1136 if (r
->arp_flags
& ATF_PUBL
)
1137 return arp_req_delete_public(net
, r
, dev
);
1139 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
1141 struct rtable
*rt
= ip_route_output(net
, ip
, 0, RTO_ONLINK
, 0);
1149 return arp_invalidate(dev
, ip
);
1153 * Handle an ARP layer I/O control request.
1156 int arp_ioctl(struct net
*net
, unsigned int cmd
, void __user
*arg
)
1160 struct net_device
*dev
= NULL
;
1165 if (!capable(CAP_NET_ADMIN
))
1168 err
= copy_from_user(&r
, arg
, sizeof(struct arpreq
));
1176 if (r
.arp_pa
.sa_family
!= AF_INET
)
1177 return -EPFNOSUPPORT
;
1179 if (!(r
.arp_flags
& ATF_PUBL
) &&
1180 (r
.arp_flags
& (ATF_NETMASK
| ATF_DONTPUB
)))
1182 if (!(r
.arp_flags
& ATF_NETMASK
))
1183 ((struct sockaddr_in
*)&r
.arp_netmask
)->sin_addr
.s_addr
=
1184 htonl(0xFFFFFFFFUL
);
1188 dev
= __dev_get_by_name(net
, r
.arp_dev
);
1192 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1193 if (!r
.arp_ha
.sa_family
)
1194 r
.arp_ha
.sa_family
= dev
->type
;
1196 if ((r
.arp_flags
& ATF_COM
) && r
.arp_ha
.sa_family
!= dev
->type
)
1198 } else if (cmd
== SIOCGARP
) {
1205 err
= arp_req_delete(net
, &r
, dev
);
1208 err
= arp_req_set(net
, &r
, dev
);
1211 err
= arp_req_get(&r
, dev
);
1216 if (cmd
== SIOCGARP
&& !err
&& copy_to_user(arg
, &r
, sizeof(r
)))
1221 static int arp_netdev_event(struct notifier_block
*this, unsigned long event
,
1224 struct net_device
*dev
= ptr
;
1227 case NETDEV_CHANGEADDR
:
1228 neigh_changeaddr(&arp_tbl
, dev
);
1229 rt_cache_flush(dev_net(dev
), 0);
1238 static struct notifier_block arp_netdev_notifier
= {
1239 .notifier_call
= arp_netdev_event
,
1242 /* Note, that it is not on notifier chain.
1243 It is necessary, that this routine was called after route cache will be
1246 void arp_ifdown(struct net_device
*dev
)
1248 neigh_ifdown(&arp_tbl
, dev
);
1253 * Called once on startup.
1256 static struct packet_type arp_packet_type __read_mostly
= {
1257 .type
= cpu_to_be16(ETH_P_ARP
),
1261 static int arp_proc_init(void);
1263 void __init
arp_init(void)
1265 neigh_table_init(&arp_tbl
);
1267 dev_add_pack(&arp_packet_type
);
1269 #ifdef CONFIG_SYSCTL
1270 neigh_sysctl_register(NULL
, &arp_tbl
.parms
, "ipv4", NULL
);
1272 register_netdevice_notifier(&arp_netdev_notifier
);
1275 #ifdef CONFIG_PROC_FS
1276 #if IS_ENABLED(CONFIG_AX25)
1278 /* ------------------------------------------------------------------------ */
1280 * ax25 -> ASCII conversion
1282 static char *ax2asc2(ax25_address
*a
, char *buf
)
1287 for (n
= 0, s
= buf
; n
< 6; n
++) {
1288 c
= (a
->ax25_call
[n
] >> 1) & 0x7F;
1295 n
= (a
->ax25_call
[6] >> 1) & 0x0F;
1304 if (*buf
== '\0' || *buf
== '-')
1309 #endif /* CONFIG_AX25 */
1311 #define HBUFFERLEN 30
1313 static void arp_format_neigh_entry(struct seq_file
*seq
,
1314 struct neighbour
*n
)
1316 char hbuffer
[HBUFFERLEN
];
1319 struct net_device
*dev
= n
->dev
;
1320 int hatype
= dev
->type
;
1322 read_lock(&n
->lock
);
1323 /* Convert hardware address to XX:XX:XX:XX ... form. */
1324 #if IS_ENABLED(CONFIG_AX25)
1325 if (hatype
== ARPHRD_AX25
|| hatype
== ARPHRD_NETROM
)
1326 ax2asc2((ax25_address
*)n
->ha
, hbuffer
);
1329 for (k
= 0, j
= 0; k
< HBUFFERLEN
- 3 && j
< dev
->addr_len
; j
++) {
1330 hbuffer
[k
++] = hex_asc_hi(n
->ha
[j
]);
1331 hbuffer
[k
++] = hex_asc_lo(n
->ha
[j
]);
1337 #if IS_ENABLED(CONFIG_AX25)
1340 sprintf(tbuf
, "%pI4", n
->primary_key
);
1341 seq_printf(seq
, "%-16s 0x%-10x0x%-10x%s * %s\n",
1342 tbuf
, hatype
, arp_state_to_flags(n
), hbuffer
, dev
->name
);
1343 read_unlock(&n
->lock
);
1346 static void arp_format_pneigh_entry(struct seq_file
*seq
,
1347 struct pneigh_entry
*n
)
1349 struct net_device
*dev
= n
->dev
;
1350 int hatype
= dev
? dev
->type
: 0;
1353 sprintf(tbuf
, "%pI4", n
->key
);
1354 seq_printf(seq
, "%-16s 0x%-10x0x%-10x%s * %s\n",
1355 tbuf
, hatype
, ATF_PUBL
| ATF_PERM
, "00:00:00:00:00:00",
1356 dev
? dev
->name
: "*");
1359 static int arp_seq_show(struct seq_file
*seq
, void *v
)
1361 if (v
== SEQ_START_TOKEN
) {
1362 seq_puts(seq
, "IP address HW type Flags "
1363 "HW address Mask Device\n");
1365 struct neigh_seq_state
*state
= seq
->private;
1367 if (state
->flags
& NEIGH_SEQ_IS_PNEIGH
)
1368 arp_format_pneigh_entry(seq
, v
);
1370 arp_format_neigh_entry(seq
, v
);
1376 static void *arp_seq_start(struct seq_file
*seq
, loff_t
*pos
)
1378 /* Don't want to confuse "arp -a" w/ magic entries,
1379 * so we tell the generic iterator to skip NUD_NOARP.
1381 return neigh_seq_start(seq
, pos
, &arp_tbl
, NEIGH_SEQ_SKIP_NOARP
);
1384 /* ------------------------------------------------------------------------ */
1386 static const struct seq_operations arp_seq_ops
= {
1387 .start
= arp_seq_start
,
1388 .next
= neigh_seq_next
,
1389 .stop
= neigh_seq_stop
,
1390 .show
= arp_seq_show
,
1393 static int arp_seq_open(struct inode
*inode
, struct file
*file
)
1395 return seq_open_net(inode
, file
, &arp_seq_ops
,
1396 sizeof(struct neigh_seq_state
));
1399 static const struct file_operations arp_seq_fops
= {
1400 .owner
= THIS_MODULE
,
1401 .open
= arp_seq_open
,
1403 .llseek
= seq_lseek
,
1404 .release
= seq_release_net
,
1408 static int __net_init
arp_net_init(struct net
*net
)
1410 if (!proc_net_fops_create(net
, "arp", S_IRUGO
, &arp_seq_fops
))
1415 static void __net_exit
arp_net_exit(struct net
*net
)
1417 proc_net_remove(net
, "arp");
1420 static struct pernet_operations arp_net_ops
= {
1421 .init
= arp_net_init
,
1422 .exit
= arp_net_exit
,
1425 static int __init
arp_proc_init(void)
1427 return register_pernet_subsys(&arp_net_ops
);
1430 #else /* CONFIG_PROC_FS */
1432 static int __init
arp_proc_init(void)
1437 #endif /* CONFIG_PROC_FS */