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
= rt_nexthop(skb_rtable(skb
), ip_hdr(skb
)->daddr
);
479 if (arp_set_predefined(inet_addr_type(dev_net(dev
), paddr
), haddr
,
483 n
= __neigh_lookup(&arp_tbl
, &paddr
, dev
, 1);
487 if (n
->nud_state
& NUD_VALID
|| neigh_event_send(n
, skb
) == 0) {
488 neigh_ha_snapshot(haddr
, n
, dev
);
497 EXPORT_SYMBOL(arp_find
);
499 /* END OF OBSOLETE FUNCTIONS */
502 * Check if we can use proxy ARP for this path
504 static inline int arp_fwd_proxy(struct in_device
*in_dev
,
505 struct net_device
*dev
, struct rtable
*rt
)
507 struct in_device
*out_dev
;
510 if (rt
->dst
.dev
== dev
)
513 if (!IN_DEV_PROXY_ARP(in_dev
))
515 imi
= IN_DEV_MEDIUM_ID(in_dev
);
521 /* place to check for proxy_arp for routes */
523 out_dev
= __in_dev_get_rcu(rt
->dst
.dev
);
525 omi
= IN_DEV_MEDIUM_ID(out_dev
);
527 return omi
!= imi
&& omi
!= -1;
531 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
533 * RFC3069 supports proxy arp replies back to the same interface. This
534 * is done to support (ethernet) switch features, like RFC 3069, where
535 * the individual ports are not allowed to communicate with each
536 * other, BUT they are allowed to talk to the upstream router. As
537 * described in RFC 3069, it is possible to allow these hosts to
538 * communicate through the upstream router, by proxy_arp'ing.
540 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
542 * This technology is known by different names:
543 * In RFC 3069 it is called VLAN Aggregation.
544 * Cisco and Allied Telesyn call it Private VLAN.
545 * Hewlett-Packard call it Source-Port filtering or port-isolation.
546 * Ericsson call it MAC-Forced Forwarding (RFC Draft).
549 static inline int arp_fwd_pvlan(struct in_device
*in_dev
,
550 struct net_device
*dev
, struct rtable
*rt
,
551 __be32 sip
, __be32 tip
)
553 /* Private VLAN is only concerned about the same ethernet segment */
554 if (rt
->dst
.dev
!= dev
)
557 /* Don't reply on self probes (often done by windowz boxes)*/
561 if (IN_DEV_PROXY_ARP_PVLAN(in_dev
))
568 * Interface to link layer: send routine and receive handler.
572 * Create an arp packet. If (dest_hw == NULL), we create a broadcast
575 struct sk_buff
*arp_create(int type
, int ptype
, __be32 dest_ip
,
576 struct net_device
*dev
, __be32 src_ip
,
577 const unsigned char *dest_hw
,
578 const unsigned char *src_hw
,
579 const unsigned char *target_hw
)
583 unsigned char *arp_ptr
;
584 int hlen
= LL_RESERVED_SPACE(dev
);
585 int tlen
= dev
->needed_tailroom
;
591 skb
= alloc_skb(arp_hdr_len(dev
) + hlen
+ tlen
, GFP_ATOMIC
);
595 skb_reserve(skb
, hlen
);
596 skb_reset_network_header(skb
);
597 arp
= (struct arphdr
*) skb_put(skb
, arp_hdr_len(dev
));
599 skb
->protocol
= htons(ETH_P_ARP
);
601 src_hw
= dev
->dev_addr
;
603 dest_hw
= dev
->broadcast
;
606 * Fill the device header for the ARP frame
608 if (dev_hard_header(skb
, dev
, ptype
, dest_hw
, src_hw
, skb
->len
) < 0)
612 * Fill out the arp protocol part.
614 * The arp hardware type should match the device type, except for FDDI,
615 * which (according to RFC 1390) should always equal 1 (Ethernet).
618 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
619 * DIX code for the protocol. Make these device structure fields.
623 arp
->ar_hrd
= htons(dev
->type
);
624 arp
->ar_pro
= htons(ETH_P_IP
);
627 #if IS_ENABLED(CONFIG_AX25)
629 arp
->ar_hrd
= htons(ARPHRD_AX25
);
630 arp
->ar_pro
= htons(AX25_P_IP
);
633 #if IS_ENABLED(CONFIG_NETROM)
635 arp
->ar_hrd
= htons(ARPHRD_NETROM
);
636 arp
->ar_pro
= htons(AX25_P_IP
);
641 #if IS_ENABLED(CONFIG_FDDI)
643 arp
->ar_hrd
= htons(ARPHRD_ETHER
);
644 arp
->ar_pro
= htons(ETH_P_IP
);
649 arp
->ar_hln
= dev
->addr_len
;
651 arp
->ar_op
= htons(type
);
653 arp_ptr
= (unsigned char *)(arp
+ 1);
655 memcpy(arp_ptr
, src_hw
, dev
->addr_len
);
656 arp_ptr
+= dev
->addr_len
;
657 memcpy(arp_ptr
, &src_ip
, 4);
659 if (target_hw
!= NULL
)
660 memcpy(arp_ptr
, target_hw
, dev
->addr_len
);
662 memset(arp_ptr
, 0, dev
->addr_len
);
663 arp_ptr
+= dev
->addr_len
;
664 memcpy(arp_ptr
, &dest_ip
, 4);
672 EXPORT_SYMBOL(arp_create
);
675 * Send an arp packet.
677 void arp_xmit(struct sk_buff
*skb
)
679 /* Send it off, maybe filter it using firewalling first. */
680 NF_HOOK(NFPROTO_ARP
, NF_ARP_OUT
, skb
, NULL
, skb
->dev
, dev_queue_xmit
);
682 EXPORT_SYMBOL(arp_xmit
);
685 * Create and send an arp packet.
687 void arp_send(int type
, int ptype
, __be32 dest_ip
,
688 struct net_device
*dev
, __be32 src_ip
,
689 const unsigned char *dest_hw
, const unsigned char *src_hw
,
690 const unsigned char *target_hw
)
695 * No arp on this interface.
698 if (dev
->flags
&IFF_NOARP
)
701 skb
= arp_create(type
, ptype
, dest_ip
, dev
, src_ip
,
702 dest_hw
, src_hw
, target_hw
);
708 EXPORT_SYMBOL(arp_send
);
711 * Process an arp request.
714 static int arp_process(struct sk_buff
*skb
)
716 struct net_device
*dev
= skb
->dev
;
717 struct in_device
*in_dev
= __in_dev_get_rcu(dev
);
719 unsigned char *arp_ptr
;
723 u16 dev_type
= dev
->type
;
726 struct net
*net
= dev_net(dev
);
728 /* arp_rcv below verifies the ARP header and verifies the device
739 if (arp
->ar_pro
!= htons(ETH_P_IP
) ||
740 htons(dev_type
) != arp
->ar_hrd
)
747 * ETHERNET, and Fibre Channel (which are IEEE 802
748 * devices, according to RFC 2625) devices will accept ARP
749 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
750 * This is the case also of FDDI, where the RFC 1390 says that
751 * FDDI devices should accept ARP hardware of (1) Ethernet,
752 * however, to be more robust, we'll accept both 1 (Ethernet)
755 if ((arp
->ar_hrd
!= htons(ARPHRD_ETHER
) &&
756 arp
->ar_hrd
!= htons(ARPHRD_IEEE802
)) ||
757 arp
->ar_pro
!= htons(ETH_P_IP
))
761 if (arp
->ar_pro
!= htons(AX25_P_IP
) ||
762 arp
->ar_hrd
!= htons(ARPHRD_AX25
))
766 if (arp
->ar_pro
!= htons(AX25_P_IP
) ||
767 arp
->ar_hrd
!= htons(ARPHRD_NETROM
))
772 /* Understand only these message types */
774 if (arp
->ar_op
!= htons(ARPOP_REPLY
) &&
775 arp
->ar_op
!= htons(ARPOP_REQUEST
))
781 arp_ptr
= (unsigned char *)(arp
+ 1);
783 arp_ptr
+= dev
->addr_len
;
784 memcpy(&sip
, arp_ptr
, 4);
786 arp_ptr
+= dev
->addr_len
;
787 memcpy(&tip
, arp_ptr
, 4);
789 * Check for bad requests for 127.x.x.x and requests for multicast
790 * addresses. If this is one such, delete it.
792 if (ipv4_is_multicast(tip
) ||
793 (!IN_DEV_ROUTE_LOCALNET(in_dev
) && ipv4_is_loopback(tip
)))
797 * Special case: We must set Frame Relay source Q.922 address
799 if (dev_type
== ARPHRD_DLCI
)
800 sha
= dev
->broadcast
;
803 * Process entry. The idea here is we want to send a reply if it is a
804 * request for us or if it is a request for someone else that we hold
805 * a proxy for. We want to add an entry to our cache if it is a reply
806 * to us or if it is a request for our address.
807 * (The assumption for this last is that if someone is requesting our
808 * address, they are probably intending to talk to us, so it saves time
809 * if we cache their address. Their address is also probably not in
810 * our cache, since ours is not in their cache.)
812 * Putting this another way, we only care about replies if they are to
813 * us, in which case we add them to the cache. For requests, we care
814 * about those for us and those for our proxies. We reply to both,
815 * and in the case of requests for us we add the requester to the arp
819 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
821 if (arp
->ar_op
== htons(ARPOP_REQUEST
) &&
822 inet_addr_type(net
, tip
) == RTN_LOCAL
&&
823 !arp_ignore(in_dev
, sip
, tip
))
824 arp_send(ARPOP_REPLY
, ETH_P_ARP
, sip
, dev
, tip
, sha
,
829 if (arp
->ar_op
== htons(ARPOP_REQUEST
) &&
830 ip_route_input_noref(skb
, tip
, sip
, 0, dev
) == 0) {
832 rt
= skb_rtable(skb
);
833 addr_type
= rt
->rt_type
;
835 if (addr_type
== RTN_LOCAL
) {
838 dont_send
= arp_ignore(in_dev
, sip
, tip
);
839 if (!dont_send
&& IN_DEV_ARPFILTER(in_dev
))
840 dont_send
= arp_filter(sip
, tip
, dev
);
842 n
= neigh_event_ns(&arp_tbl
, sha
, &sip
, dev
);
844 arp_send(ARPOP_REPLY
, ETH_P_ARP
, sip
,
845 dev
, tip
, sha
, dev
->dev_addr
,
851 } else if (IN_DEV_FORWARD(in_dev
)) {
852 if (addr_type
== RTN_UNICAST
&&
853 (arp_fwd_proxy(in_dev
, dev
, rt
) ||
854 arp_fwd_pvlan(in_dev
, dev
, rt
, sip
, tip
) ||
855 (rt
->dst
.dev
!= dev
&&
856 pneigh_lookup(&arp_tbl
, net
, &tip
, dev
, 0)))) {
857 n
= neigh_event_ns(&arp_tbl
, sha
, &sip
, dev
);
861 if (NEIGH_CB(skb
)->flags
& LOCALLY_ENQUEUED
||
862 skb
->pkt_type
== PACKET_HOST
||
863 in_dev
->arp_parms
->proxy_delay
== 0) {
864 arp_send(ARPOP_REPLY
, ETH_P_ARP
, sip
,
865 dev
, tip
, sha
, dev
->dev_addr
,
868 pneigh_enqueue(&arp_tbl
,
869 in_dev
->arp_parms
, skb
);
877 /* Update our ARP tables */
879 n
= __neigh_lookup(&arp_tbl
, &sip
, dev
, 0);
881 if (IN_DEV_ARP_ACCEPT(in_dev
)) {
882 /* Unsolicited ARP is not accepted by default.
883 It is possible, that this option should be enabled for some
884 devices (strip is candidate)
887 (arp
->ar_op
== htons(ARPOP_REPLY
) ||
888 (arp
->ar_op
== htons(ARPOP_REQUEST
) && tip
== sip
)) &&
889 inet_addr_type(net
, sip
) == RTN_UNICAST
)
890 n
= __neigh_lookup(&arp_tbl
, &sip
, dev
, 1);
894 int state
= NUD_REACHABLE
;
897 /* If several different ARP replies follows back-to-back,
898 use the FIRST one. It is possible, if several proxy
899 agents are active. Taking the first reply prevents
900 arp trashing and chooses the fastest router.
902 override
= time_after(jiffies
, n
->updated
+ n
->parms
->locktime
);
904 /* Broadcast replies and request packets
905 do not assert neighbour reachability.
907 if (arp
->ar_op
!= htons(ARPOP_REPLY
) ||
908 skb
->pkt_type
!= PACKET_HOST
)
910 neigh_update(n
, sha
, state
,
911 override
? NEIGH_UPDATE_F_OVERRIDE
: 0);
920 static void parp_redo(struct sk_buff
*skb
)
927 * Receive an arp request from the device layer.
930 static int arp_rcv(struct sk_buff
*skb
, struct net_device
*dev
,
931 struct packet_type
*pt
, struct net_device
*orig_dev
)
935 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
936 if (!pskb_may_pull(skb
, arp_hdr_len(dev
)))
940 if (arp
->ar_hln
!= dev
->addr_len
||
941 dev
->flags
& IFF_NOARP
||
942 skb
->pkt_type
== PACKET_OTHERHOST
||
943 skb
->pkt_type
== PACKET_LOOPBACK
||
947 skb
= skb_share_check(skb
, GFP_ATOMIC
);
951 memset(NEIGH_CB(skb
), 0, sizeof(struct neighbour_cb
));
953 return NF_HOOK(NFPROTO_ARP
, NF_ARP_IN
, skb
, dev
, NULL
, arp_process
);
962 * User level interface (ioctl)
966 * Set (create) an ARP cache entry.
969 static int arp_req_set_proxy(struct net
*net
, struct net_device
*dev
, int on
)
972 IPV4_DEVCONF_ALL(net
, PROXY_ARP
) = on
;
975 if (__in_dev_get_rtnl(dev
)) {
976 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev
), PROXY_ARP
, on
);
982 static int arp_req_set_public(struct net
*net
, struct arpreq
*r
,
983 struct net_device
*dev
)
985 __be32 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
986 __be32 mask
= ((struct sockaddr_in
*)&r
->arp_netmask
)->sin_addr
.s_addr
;
988 if (mask
&& mask
!= htonl(0xFFFFFFFF))
990 if (!dev
&& (r
->arp_flags
& ATF_COM
)) {
991 dev
= dev_getbyhwaddr_rcu(net
, r
->arp_ha
.sa_family
,
997 if (pneigh_lookup(&arp_tbl
, net
, &ip
, dev
, 1) == NULL
)
1002 return arp_req_set_proxy(net
, dev
, 1);
1005 static int arp_req_set(struct net
*net
, struct arpreq
*r
,
1006 struct net_device
*dev
)
1009 struct neighbour
*neigh
;
1012 if (r
->arp_flags
& ATF_PUBL
)
1013 return arp_req_set_public(net
, r
, dev
);
1015 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
1016 if (r
->arp_flags
& ATF_PERM
)
1017 r
->arp_flags
|= ATF_COM
;
1019 struct rtable
*rt
= ip_route_output(net
, ip
, 0, RTO_ONLINK
, 0);
1028 switch (dev
->type
) {
1029 #if IS_ENABLED(CONFIG_FDDI)
1032 * According to RFC 1390, FDDI devices should accept ARP
1033 * hardware types of 1 (Ethernet). However, to be more
1034 * robust, we'll accept hardware types of either 1 (Ethernet)
1035 * or 6 (IEEE 802.2).
1037 if (r
->arp_ha
.sa_family
!= ARPHRD_FDDI
&&
1038 r
->arp_ha
.sa_family
!= ARPHRD_ETHER
&&
1039 r
->arp_ha
.sa_family
!= ARPHRD_IEEE802
)
1044 if (r
->arp_ha
.sa_family
!= dev
->type
)
1049 neigh
= __neigh_lookup_errno(&arp_tbl
, &ip
, dev
);
1050 err
= PTR_ERR(neigh
);
1051 if (!IS_ERR(neigh
)) {
1052 unsigned int state
= NUD_STALE
;
1053 if (r
->arp_flags
& ATF_PERM
)
1054 state
= NUD_PERMANENT
;
1055 err
= neigh_update(neigh
, (r
->arp_flags
& ATF_COM
) ?
1056 r
->arp_ha
.sa_data
: NULL
, state
,
1057 NEIGH_UPDATE_F_OVERRIDE
|
1058 NEIGH_UPDATE_F_ADMIN
);
1059 neigh_release(neigh
);
1064 static unsigned int arp_state_to_flags(struct neighbour
*neigh
)
1066 if (neigh
->nud_state
&NUD_PERMANENT
)
1067 return ATF_PERM
| ATF_COM
;
1068 else if (neigh
->nud_state
&NUD_VALID
)
1075 * Get an ARP cache entry.
1078 static int arp_req_get(struct arpreq
*r
, struct net_device
*dev
)
1080 __be32 ip
= ((struct sockaddr_in
*) &r
->arp_pa
)->sin_addr
.s_addr
;
1081 struct neighbour
*neigh
;
1084 neigh
= neigh_lookup(&arp_tbl
, &ip
, dev
);
1086 read_lock_bh(&neigh
->lock
);
1087 memcpy(r
->arp_ha
.sa_data
, neigh
->ha
, dev
->addr_len
);
1088 r
->arp_flags
= arp_state_to_flags(neigh
);
1089 read_unlock_bh(&neigh
->lock
);
1090 r
->arp_ha
.sa_family
= dev
->type
;
1091 strlcpy(r
->arp_dev
, dev
->name
, sizeof(r
->arp_dev
));
1092 neigh_release(neigh
);
1098 int arp_invalidate(struct net_device
*dev
, __be32 ip
)
1100 struct neighbour
*neigh
= neigh_lookup(&arp_tbl
, &ip
, dev
);
1104 if (neigh
->nud_state
& ~NUD_NOARP
)
1105 err
= neigh_update(neigh
, NULL
, NUD_FAILED
,
1106 NEIGH_UPDATE_F_OVERRIDE
|
1107 NEIGH_UPDATE_F_ADMIN
);
1108 neigh_release(neigh
);
1113 EXPORT_SYMBOL(arp_invalidate
);
1115 static int arp_req_delete_public(struct net
*net
, struct arpreq
*r
,
1116 struct net_device
*dev
)
1118 __be32 ip
= ((struct sockaddr_in
*) &r
->arp_pa
)->sin_addr
.s_addr
;
1119 __be32 mask
= ((struct sockaddr_in
*)&r
->arp_netmask
)->sin_addr
.s_addr
;
1121 if (mask
== htonl(0xFFFFFFFF))
1122 return pneigh_delete(&arp_tbl
, net
, &ip
, dev
);
1127 return arp_req_set_proxy(net
, dev
, 0);
1130 static int arp_req_delete(struct net
*net
, struct arpreq
*r
,
1131 struct net_device
*dev
)
1135 if (r
->arp_flags
& ATF_PUBL
)
1136 return arp_req_delete_public(net
, r
, dev
);
1138 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
1140 struct rtable
*rt
= ip_route_output(net
, ip
, 0, RTO_ONLINK
, 0);
1148 return arp_invalidate(dev
, ip
);
1152 * Handle an ARP layer I/O control request.
1155 int arp_ioctl(struct net
*net
, unsigned int cmd
, void __user
*arg
)
1159 struct net_device
*dev
= NULL
;
1164 if (!ns_capable(net
->user_ns
, CAP_NET_ADMIN
))
1167 err
= copy_from_user(&r
, arg
, sizeof(struct arpreq
));
1175 if (r
.arp_pa
.sa_family
!= AF_INET
)
1176 return -EPFNOSUPPORT
;
1178 if (!(r
.arp_flags
& ATF_PUBL
) &&
1179 (r
.arp_flags
& (ATF_NETMASK
| ATF_DONTPUB
)))
1181 if (!(r
.arp_flags
& ATF_NETMASK
))
1182 ((struct sockaddr_in
*)&r
.arp_netmask
)->sin_addr
.s_addr
=
1183 htonl(0xFFFFFFFFUL
);
1187 dev
= __dev_get_by_name(net
, r
.arp_dev
);
1191 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1192 if (!r
.arp_ha
.sa_family
)
1193 r
.arp_ha
.sa_family
= dev
->type
;
1195 if ((r
.arp_flags
& ATF_COM
) && r
.arp_ha
.sa_family
!= dev
->type
)
1197 } else if (cmd
== SIOCGARP
) {
1204 err
= arp_req_delete(net
, &r
, dev
);
1207 err
= arp_req_set(net
, &r
, dev
);
1210 err
= arp_req_get(&r
, dev
);
1215 if (cmd
== SIOCGARP
&& !err
&& copy_to_user(arg
, &r
, sizeof(r
)))
1220 static int arp_netdev_event(struct notifier_block
*this, unsigned long event
,
1223 struct net_device
*dev
= ptr
;
1226 case NETDEV_CHANGEADDR
:
1227 neigh_changeaddr(&arp_tbl
, dev
);
1228 rt_cache_flush(dev_net(dev
));
1237 static struct notifier_block arp_netdev_notifier
= {
1238 .notifier_call
= arp_netdev_event
,
1241 /* Note, that it is not on notifier chain.
1242 It is necessary, that this routine was called after route cache will be
1245 void arp_ifdown(struct net_device
*dev
)
1247 neigh_ifdown(&arp_tbl
, dev
);
1252 * Called once on startup.
1255 static struct packet_type arp_packet_type __read_mostly
= {
1256 .type
= cpu_to_be16(ETH_P_ARP
),
1260 static int arp_proc_init(void);
1262 void __init
arp_init(void)
1264 neigh_table_init(&arp_tbl
);
1266 dev_add_pack(&arp_packet_type
);
1268 #ifdef CONFIG_SYSCTL
1269 neigh_sysctl_register(NULL
, &arp_tbl
.parms
, "ipv4", NULL
);
1271 register_netdevice_notifier(&arp_netdev_notifier
);
1274 #ifdef CONFIG_PROC_FS
1275 #if IS_ENABLED(CONFIG_AX25)
1277 /* ------------------------------------------------------------------------ */
1279 * ax25 -> ASCII conversion
1281 static char *ax2asc2(ax25_address
*a
, char *buf
)
1286 for (n
= 0, s
= buf
; n
< 6; n
++) {
1287 c
= (a
->ax25_call
[n
] >> 1) & 0x7F;
1294 n
= (a
->ax25_call
[6] >> 1) & 0x0F;
1303 if (*buf
== '\0' || *buf
== '-')
1308 #endif /* CONFIG_AX25 */
1310 #define HBUFFERLEN 30
1312 static void arp_format_neigh_entry(struct seq_file
*seq
,
1313 struct neighbour
*n
)
1315 char hbuffer
[HBUFFERLEN
];
1318 struct net_device
*dev
= n
->dev
;
1319 int hatype
= dev
->type
;
1321 read_lock(&n
->lock
);
1322 /* Convert hardware address to XX:XX:XX:XX ... form. */
1323 #if IS_ENABLED(CONFIG_AX25)
1324 if (hatype
== ARPHRD_AX25
|| hatype
== ARPHRD_NETROM
)
1325 ax2asc2((ax25_address
*)n
->ha
, hbuffer
);
1328 for (k
= 0, j
= 0; k
< HBUFFERLEN
- 3 && j
< dev
->addr_len
; j
++) {
1329 hbuffer
[k
++] = hex_asc_hi(n
->ha
[j
]);
1330 hbuffer
[k
++] = hex_asc_lo(n
->ha
[j
]);
1336 #if IS_ENABLED(CONFIG_AX25)
1339 sprintf(tbuf
, "%pI4", n
->primary_key
);
1340 seq_printf(seq
, "%-16s 0x%-10x0x%-10x%s * %s\n",
1341 tbuf
, hatype
, arp_state_to_flags(n
), hbuffer
, dev
->name
);
1342 read_unlock(&n
->lock
);
1345 static void arp_format_pneigh_entry(struct seq_file
*seq
,
1346 struct pneigh_entry
*n
)
1348 struct net_device
*dev
= n
->dev
;
1349 int hatype
= dev
? dev
->type
: 0;
1352 sprintf(tbuf
, "%pI4", n
->key
);
1353 seq_printf(seq
, "%-16s 0x%-10x0x%-10x%s * %s\n",
1354 tbuf
, hatype
, ATF_PUBL
| ATF_PERM
, "00:00:00:00:00:00",
1355 dev
? dev
->name
: "*");
1358 static int arp_seq_show(struct seq_file
*seq
, void *v
)
1360 if (v
== SEQ_START_TOKEN
) {
1361 seq_puts(seq
, "IP address HW type Flags "
1362 "HW address Mask Device\n");
1364 struct neigh_seq_state
*state
= seq
->private;
1366 if (state
->flags
& NEIGH_SEQ_IS_PNEIGH
)
1367 arp_format_pneigh_entry(seq
, v
);
1369 arp_format_neigh_entry(seq
, v
);
1375 static void *arp_seq_start(struct seq_file
*seq
, loff_t
*pos
)
1377 /* Don't want to confuse "arp -a" w/ magic entries,
1378 * so we tell the generic iterator to skip NUD_NOARP.
1380 return neigh_seq_start(seq
, pos
, &arp_tbl
, NEIGH_SEQ_SKIP_NOARP
);
1383 /* ------------------------------------------------------------------------ */
1385 static const struct seq_operations arp_seq_ops
= {
1386 .start
= arp_seq_start
,
1387 .next
= neigh_seq_next
,
1388 .stop
= neigh_seq_stop
,
1389 .show
= arp_seq_show
,
1392 static int arp_seq_open(struct inode
*inode
, struct file
*file
)
1394 return seq_open_net(inode
, file
, &arp_seq_ops
,
1395 sizeof(struct neigh_seq_state
));
1398 static const struct file_operations arp_seq_fops
= {
1399 .owner
= THIS_MODULE
,
1400 .open
= arp_seq_open
,
1402 .llseek
= seq_lseek
,
1403 .release
= seq_release_net
,
1407 static int __net_init
arp_net_init(struct net
*net
)
1409 if (!proc_net_fops_create(net
, "arp", S_IRUGO
, &arp_seq_fops
))
1414 static void __net_exit
arp_net_exit(struct net
*net
)
1416 proc_net_remove(net
, "arp");
1419 static struct pernet_operations arp_net_ops
= {
1420 .init
= arp_net_init
,
1421 .exit
= arp_net_exit
,
1424 static int __init
arp_proc_init(void)
1426 return register_pernet_subsys(&arp_net_ops
);
1429 #else /* CONFIG_PROC_FS */
1431 static int __init
arp_proc_init(void)
1436 #endif /* CONFIG_PROC_FS */