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>
116 #include <net/dst_metadata.h>
117 #include <net/ip_tunnels.h>
119 #include <linux/uaccess.h>
121 #include <linux/netfilter_arp.h>
124 * Interface to generic neighbour cache.
126 static u32
arp_hash(const void *pkey
, const struct net_device
*dev
, __u32
*hash_rnd
);
127 static bool arp_key_eq(const struct neighbour
*n
, const void *pkey
);
128 static int arp_constructor(struct neighbour
*neigh
);
129 static void arp_solicit(struct neighbour
*neigh
, struct sk_buff
*skb
);
130 static void arp_error_report(struct neighbour
*neigh
, struct sk_buff
*skb
);
131 static void parp_redo(struct sk_buff
*skb
);
133 static const struct neigh_ops arp_generic_ops
= {
135 .solicit
= arp_solicit
,
136 .error_report
= arp_error_report
,
137 .output
= neigh_resolve_output
,
138 .connected_output
= neigh_connected_output
,
141 static const struct neigh_ops arp_hh_ops
= {
143 .solicit
= arp_solicit
,
144 .error_report
= arp_error_report
,
145 .output
= neigh_resolve_output
,
146 .connected_output
= neigh_resolve_output
,
149 static const struct neigh_ops arp_direct_ops
= {
151 .output
= neigh_direct_output
,
152 .connected_output
= neigh_direct_output
,
155 struct neigh_table arp_tbl
= {
158 .protocol
= cpu_to_be16(ETH_P_IP
),
160 .key_eq
= arp_key_eq
,
161 .constructor
= arp_constructor
,
162 .proxy_redo
= parp_redo
,
166 .reachable_time
= 30 * HZ
,
168 [NEIGH_VAR_MCAST_PROBES
] = 3,
169 [NEIGH_VAR_UCAST_PROBES
] = 3,
170 [NEIGH_VAR_RETRANS_TIME
] = 1 * HZ
,
171 [NEIGH_VAR_BASE_REACHABLE_TIME
] = 30 * HZ
,
172 [NEIGH_VAR_DELAY_PROBE_TIME
] = 5 * HZ
,
173 [NEIGH_VAR_GC_STALETIME
] = 60 * HZ
,
174 [NEIGH_VAR_QUEUE_LEN_BYTES
] = 64 * 1024,
175 [NEIGH_VAR_PROXY_QLEN
] = 64,
176 [NEIGH_VAR_ANYCAST_DELAY
] = 1 * HZ
,
177 [NEIGH_VAR_PROXY_DELAY
] = (8 * HZ
) / 10,
178 [NEIGH_VAR_LOCKTIME
] = 1 * HZ
,
181 .gc_interval
= 30 * HZ
,
186 EXPORT_SYMBOL(arp_tbl
);
188 int arp_mc_map(__be32 addr
, u8
*haddr
, struct net_device
*dev
, int dir
)
194 ip_eth_mc_map(addr
, haddr
);
196 case ARPHRD_INFINIBAND
:
197 ip_ib_mc_map(addr
, dev
->broadcast
, haddr
);
200 ip_ipgre_mc_map(addr
, dev
->broadcast
, haddr
);
204 memcpy(haddr
, dev
->broadcast
, dev
->addr_len
);
212 static u32
arp_hash(const void *pkey
,
213 const struct net_device
*dev
,
216 return arp_hashfn(pkey
, dev
, hash_rnd
);
219 static bool arp_key_eq(const struct neighbour
*neigh
, const void *pkey
)
221 return neigh_key_eq32(neigh
, pkey
);
224 static int arp_constructor(struct neighbour
*neigh
)
226 __be32 addr
= *(__be32
*)neigh
->primary_key
;
227 struct net_device
*dev
= neigh
->dev
;
228 struct in_device
*in_dev
;
229 struct neigh_parms
*parms
;
232 in_dev
= __in_dev_get_rcu(dev
);
238 neigh
->type
= inet_addr_type_dev_table(dev_net(dev
), dev
, addr
);
240 parms
= in_dev
->arp_parms
;
241 __neigh_parms_put(neigh
->parms
);
242 neigh
->parms
= neigh_parms_clone(parms
);
245 if (!dev
->header_ops
) {
246 neigh
->nud_state
= NUD_NOARP
;
247 neigh
->ops
= &arp_direct_ops
;
248 neigh
->output
= neigh_direct_output
;
250 /* Good devices (checked by reading texts, but only Ethernet is
253 ARPHRD_ETHER: (ethernet, apfddi)
256 ARPHRD_METRICOM: (strip)
260 ARPHRD_IPDDP will also work, if author repairs it.
261 I did not it, because this driver does not work even
265 if (neigh
->type
== RTN_MULTICAST
) {
266 neigh
->nud_state
= NUD_NOARP
;
267 arp_mc_map(addr
, neigh
->ha
, dev
, 1);
268 } else if (dev
->flags
& (IFF_NOARP
| IFF_LOOPBACK
)) {
269 neigh
->nud_state
= NUD_NOARP
;
270 memcpy(neigh
->ha
, dev
->dev_addr
, dev
->addr_len
);
271 } else if (neigh
->type
== RTN_BROADCAST
||
272 (dev
->flags
& IFF_POINTOPOINT
)) {
273 neigh
->nud_state
= NUD_NOARP
;
274 memcpy(neigh
->ha
, dev
->broadcast
, dev
->addr_len
);
277 if (dev
->header_ops
->cache
)
278 neigh
->ops
= &arp_hh_ops
;
280 neigh
->ops
= &arp_generic_ops
;
282 if (neigh
->nud_state
& NUD_VALID
)
283 neigh
->output
= neigh
->ops
->connected_output
;
285 neigh
->output
= neigh
->ops
->output
;
290 static void arp_error_report(struct neighbour
*neigh
, struct sk_buff
*skb
)
292 dst_link_failure(skb
);
296 /* Create and send an arp packet. */
297 static void arp_send_dst(int type
, int ptype
, __be32 dest_ip
,
298 struct net_device
*dev
, __be32 src_ip
,
299 const unsigned char *dest_hw
,
300 const unsigned char *src_hw
,
301 const unsigned char *target_hw
,
302 struct dst_entry
*dst
)
306 /* arp on this interface. */
307 if (dev
->flags
& IFF_NOARP
)
310 skb
= arp_create(type
, ptype
, dest_ip
, dev
, src_ip
,
311 dest_hw
, src_hw
, target_hw
);
315 skb_dst_set(skb
, dst_clone(dst
));
319 void arp_send(int type
, int ptype
, __be32 dest_ip
,
320 struct net_device
*dev
, __be32 src_ip
,
321 const unsigned char *dest_hw
, const unsigned char *src_hw
,
322 const unsigned char *target_hw
)
324 arp_send_dst(type
, ptype
, dest_ip
, dev
, src_ip
, dest_hw
, src_hw
,
327 EXPORT_SYMBOL(arp_send
);
329 static void arp_solicit(struct neighbour
*neigh
, struct sk_buff
*skb
)
332 u8 dst_ha
[MAX_ADDR_LEN
], *dst_hw
= NULL
;
333 struct net_device
*dev
= neigh
->dev
;
334 __be32 target
= *(__be32
*)neigh
->primary_key
;
335 int probes
= atomic_read(&neigh
->probes
);
336 struct in_device
*in_dev
;
337 struct dst_entry
*dst
= NULL
;
340 in_dev
= __in_dev_get_rcu(dev
);
345 switch (IN_DEV_ARP_ANNOUNCE(in_dev
)) {
347 case 0: /* By default announce any local IP */
348 if (skb
&& inet_addr_type_dev_table(dev_net(dev
), dev
,
349 ip_hdr(skb
)->saddr
) == RTN_LOCAL
)
350 saddr
= ip_hdr(skb
)->saddr
;
352 case 1: /* Restrict announcements of saddr in same subnet */
355 saddr
= ip_hdr(skb
)->saddr
;
356 if (inet_addr_type_dev_table(dev_net(dev
), dev
,
357 saddr
) == RTN_LOCAL
) {
358 /* saddr should be known to target */
359 if (inet_addr_onlink(in_dev
, target
, saddr
))
364 case 2: /* Avoid secondary IPs, get a primary/preferred one */
370 saddr
= inet_select_addr(dev
, target
, RT_SCOPE_LINK
);
372 probes
-= NEIGH_VAR(neigh
->parms
, UCAST_PROBES
);
374 if (!(neigh
->nud_state
& NUD_VALID
))
375 pr_debug("trying to ucast probe in NUD_INVALID\n");
376 neigh_ha_snapshot(dst_ha
, neigh
, dev
);
379 probes
-= NEIGH_VAR(neigh
->parms
, APP_PROBES
);
386 if (skb
&& !(dev
->priv_flags
& IFF_XMIT_DST_RELEASE
))
388 arp_send_dst(ARPOP_REQUEST
, ETH_P_ARP
, target
, dev
, saddr
,
389 dst_hw
, dev
->dev_addr
, NULL
, dst
);
392 static int arp_ignore(struct in_device
*in_dev
, __be32 sip
, __be32 tip
)
394 struct net
*net
= dev_net(in_dev
->dev
);
397 switch (IN_DEV_ARP_IGNORE(in_dev
)) {
398 case 0: /* Reply, the tip is already validated */
400 case 1: /* Reply only if tip is configured on the incoming interface */
402 scope
= RT_SCOPE_HOST
;
405 * Reply only if tip is configured on the incoming interface
406 * and is in same subnet as sip
408 scope
= RT_SCOPE_HOST
;
410 case 3: /* Do not reply for scope host addresses */
412 scope
= RT_SCOPE_LINK
;
415 case 4: /* Reserved */
420 case 8: /* Do not reply */
425 return !inet_confirm_addr(net
, in_dev
, sip
, tip
, scope
);
428 static int arp_filter(__be32 sip
, __be32 tip
, struct net_device
*dev
)
432 /*unsigned long now; */
433 struct net
*net
= dev_net(dev
);
435 rt
= ip_route_output(net
, sip
, tip
, 0, 0);
438 if (rt
->dst
.dev
!= dev
) {
439 NET_INC_STATS_BH(net
, LINUX_MIB_ARPFILTER
);
447 * Check if we can use proxy ARP for this path
449 static inline int arp_fwd_proxy(struct in_device
*in_dev
,
450 struct net_device
*dev
, struct rtable
*rt
)
452 struct in_device
*out_dev
;
455 if (rt
->dst
.dev
== dev
)
458 if (!IN_DEV_PROXY_ARP(in_dev
))
460 imi
= IN_DEV_MEDIUM_ID(in_dev
);
466 /* place to check for proxy_arp for routes */
468 out_dev
= __in_dev_get_rcu(rt
->dst
.dev
);
470 omi
= IN_DEV_MEDIUM_ID(out_dev
);
472 return omi
!= imi
&& omi
!= -1;
476 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
478 * RFC3069 supports proxy arp replies back to the same interface. This
479 * is done to support (ethernet) switch features, like RFC 3069, where
480 * the individual ports are not allowed to communicate with each
481 * other, BUT they are allowed to talk to the upstream router. As
482 * described in RFC 3069, it is possible to allow these hosts to
483 * communicate through the upstream router, by proxy_arp'ing.
485 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
487 * This technology is known by different names:
488 * In RFC 3069 it is called VLAN Aggregation.
489 * Cisco and Allied Telesyn call it Private VLAN.
490 * Hewlett-Packard call it Source-Port filtering or port-isolation.
491 * Ericsson call it MAC-Forced Forwarding (RFC Draft).
494 static inline int arp_fwd_pvlan(struct in_device
*in_dev
,
495 struct net_device
*dev
, struct rtable
*rt
,
496 __be32 sip
, __be32 tip
)
498 /* Private VLAN is only concerned about the same ethernet segment */
499 if (rt
->dst
.dev
!= dev
)
502 /* Don't reply on self probes (often done by windowz boxes)*/
506 if (IN_DEV_PROXY_ARP_PVLAN(in_dev
))
513 * Interface to link layer: send routine and receive handler.
517 * Create an arp packet. If dest_hw is not set, we create a broadcast
520 struct sk_buff
*arp_create(int type
, int ptype
, __be32 dest_ip
,
521 struct net_device
*dev
, __be32 src_ip
,
522 const unsigned char *dest_hw
,
523 const unsigned char *src_hw
,
524 const unsigned char *target_hw
)
528 unsigned char *arp_ptr
;
529 int hlen
= LL_RESERVED_SPACE(dev
);
530 int tlen
= dev
->needed_tailroom
;
536 skb
= alloc_skb(arp_hdr_len(dev
) + hlen
+ tlen
, GFP_ATOMIC
);
540 skb_reserve(skb
, hlen
);
541 skb_reset_network_header(skb
);
542 arp
= (struct arphdr
*) skb_put(skb
, arp_hdr_len(dev
));
544 skb
->protocol
= htons(ETH_P_ARP
);
546 src_hw
= dev
->dev_addr
;
548 dest_hw
= dev
->broadcast
;
551 * Fill the device header for the ARP frame
553 if (dev_hard_header(skb
, dev
, ptype
, dest_hw
, src_hw
, skb
->len
) < 0)
557 * Fill out the arp protocol part.
559 * The arp hardware type should match the device type, except for FDDI,
560 * which (according to RFC 1390) should always equal 1 (Ethernet).
563 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
564 * DIX code for the protocol. Make these device structure fields.
568 arp
->ar_hrd
= htons(dev
->type
);
569 arp
->ar_pro
= htons(ETH_P_IP
);
572 #if IS_ENABLED(CONFIG_AX25)
574 arp
->ar_hrd
= htons(ARPHRD_AX25
);
575 arp
->ar_pro
= htons(AX25_P_IP
);
578 #if IS_ENABLED(CONFIG_NETROM)
580 arp
->ar_hrd
= htons(ARPHRD_NETROM
);
581 arp
->ar_pro
= htons(AX25_P_IP
);
586 #if IS_ENABLED(CONFIG_FDDI)
588 arp
->ar_hrd
= htons(ARPHRD_ETHER
);
589 arp
->ar_pro
= htons(ETH_P_IP
);
594 arp
->ar_hln
= dev
->addr_len
;
596 arp
->ar_op
= htons(type
);
598 arp_ptr
= (unsigned char *)(arp
+ 1);
600 memcpy(arp_ptr
, src_hw
, dev
->addr_len
);
601 arp_ptr
+= dev
->addr_len
;
602 memcpy(arp_ptr
, &src_ip
, 4);
606 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
607 case ARPHRD_IEEE1394
:
612 memcpy(arp_ptr
, target_hw
, dev
->addr_len
);
614 memset(arp_ptr
, 0, dev
->addr_len
);
615 arp_ptr
+= dev
->addr_len
;
617 memcpy(arp_ptr
, &dest_ip
, 4);
625 EXPORT_SYMBOL(arp_create
);
628 * Send an arp packet.
630 void arp_xmit(struct sk_buff
*skb
)
632 /* Send it off, maybe filter it using firewalling first. */
633 NF_HOOK(NFPROTO_ARP
, NF_ARP_OUT
, NULL
, skb
,
634 NULL
, skb
->dev
, dev_queue_xmit_sk
);
636 EXPORT_SYMBOL(arp_xmit
);
639 * Process an arp request.
642 static int arp_process(struct sock
*sk
, struct sk_buff
*skb
)
644 struct net_device
*dev
= skb
->dev
;
645 struct in_device
*in_dev
= __in_dev_get_rcu(dev
);
647 unsigned char *arp_ptr
;
651 u16 dev_type
= dev
->type
;
654 struct net
*net
= dev_net(dev
);
655 struct dst_entry
*reply_dst
= NULL
;
656 bool is_garp
= false;
658 /* arp_rcv below verifies the ARP header and verifies the device
669 if (arp
->ar_pro
!= htons(ETH_P_IP
) ||
670 htons(dev_type
) != arp
->ar_hrd
)
677 * ETHERNET, and Fibre Channel (which are IEEE 802
678 * devices, according to RFC 2625) devices will accept ARP
679 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
680 * This is the case also of FDDI, where the RFC 1390 says that
681 * FDDI devices should accept ARP hardware of (1) Ethernet,
682 * however, to be more robust, we'll accept both 1 (Ethernet)
685 if ((arp
->ar_hrd
!= htons(ARPHRD_ETHER
) &&
686 arp
->ar_hrd
!= htons(ARPHRD_IEEE802
)) ||
687 arp
->ar_pro
!= htons(ETH_P_IP
))
691 if (arp
->ar_pro
!= htons(AX25_P_IP
) ||
692 arp
->ar_hrd
!= htons(ARPHRD_AX25
))
696 if (arp
->ar_pro
!= htons(AX25_P_IP
) ||
697 arp
->ar_hrd
!= htons(ARPHRD_NETROM
))
702 /* Understand only these message types */
704 if (arp
->ar_op
!= htons(ARPOP_REPLY
) &&
705 arp
->ar_op
!= htons(ARPOP_REQUEST
))
711 arp_ptr
= (unsigned char *)(arp
+ 1);
713 arp_ptr
+= dev
->addr_len
;
714 memcpy(&sip
, arp_ptr
, 4);
717 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
718 case ARPHRD_IEEE1394
:
722 arp_ptr
+= dev
->addr_len
;
724 memcpy(&tip
, arp_ptr
, 4);
726 * Check for bad requests for 127.x.x.x and requests for multicast
727 * addresses. If this is one such, delete it.
729 if (ipv4_is_multicast(tip
) ||
730 (!IN_DEV_ROUTE_LOCALNET(in_dev
) && ipv4_is_loopback(tip
)))
734 * Special case: We must set Frame Relay source Q.922 address
736 if (dev_type
== ARPHRD_DLCI
)
737 sha
= dev
->broadcast
;
740 * Process entry. The idea here is we want to send a reply if it is a
741 * request for us or if it is a request for someone else that we hold
742 * a proxy for. We want to add an entry to our cache if it is a reply
743 * to us or if it is a request for our address.
744 * (The assumption for this last is that if someone is requesting our
745 * address, they are probably intending to talk to us, so it saves time
746 * if we cache their address. Their address is also probably not in
747 * our cache, since ours is not in their cache.)
749 * Putting this another way, we only care about replies if they are to
750 * us, in which case we add them to the cache. For requests, we care
751 * about those for us and those for our proxies. We reply to both,
752 * and in the case of requests for us we add the requester to the arp
756 if (arp
->ar_op
== htons(ARPOP_REQUEST
) && skb_metadata_dst(skb
))
757 reply_dst
= (struct dst_entry
*)
758 iptunnel_metadata_reply(skb_metadata_dst(skb
),
761 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
763 if (arp
->ar_op
== htons(ARPOP_REQUEST
) &&
764 inet_addr_type_dev_table(net
, dev
, tip
) == RTN_LOCAL
&&
765 !arp_ignore(in_dev
, sip
, tip
))
766 arp_send_dst(ARPOP_REPLY
, ETH_P_ARP
, sip
, dev
, tip
,
767 sha
, dev
->dev_addr
, sha
, reply_dst
);
771 if (arp
->ar_op
== htons(ARPOP_REQUEST
) &&
772 ip_route_input_noref(skb
, tip
, sip
, 0, dev
) == 0) {
774 rt
= skb_rtable(skb
);
775 addr_type
= rt
->rt_type
;
777 if (addr_type
== RTN_LOCAL
) {
780 dont_send
= arp_ignore(in_dev
, sip
, tip
);
781 if (!dont_send
&& IN_DEV_ARPFILTER(in_dev
))
782 dont_send
= arp_filter(sip
, tip
, dev
);
784 n
= neigh_event_ns(&arp_tbl
, sha
, &sip
, dev
);
786 arp_send_dst(ARPOP_REPLY
, ETH_P_ARP
,
794 } else if (IN_DEV_FORWARD(in_dev
)) {
795 if (addr_type
== RTN_UNICAST
&&
796 (arp_fwd_proxy(in_dev
, dev
, rt
) ||
797 arp_fwd_pvlan(in_dev
, dev
, rt
, sip
, tip
) ||
798 (rt
->dst
.dev
!= dev
&&
799 pneigh_lookup(&arp_tbl
, net
, &tip
, dev
, 0)))) {
800 n
= neigh_event_ns(&arp_tbl
, sha
, &sip
, dev
);
804 if (NEIGH_CB(skb
)->flags
& LOCALLY_ENQUEUED
||
805 skb
->pkt_type
== PACKET_HOST
||
806 NEIGH_VAR(in_dev
->arp_parms
, PROXY_DELAY
) == 0) {
807 arp_send_dst(ARPOP_REPLY
, ETH_P_ARP
,
812 pneigh_enqueue(&arp_tbl
,
813 in_dev
->arp_parms
, skb
);
821 /* Update our ARP tables */
823 n
= __neigh_lookup(&arp_tbl
, &sip
, dev
, 0);
825 if (IN_DEV_ARP_ACCEPT(in_dev
)) {
826 unsigned int addr_type
= inet_addr_type_dev_table(net
, dev
, sip
);
828 /* Unsolicited ARP is not accepted by default.
829 It is possible, that this option should be enabled for some
830 devices (strip is candidate)
832 is_garp
= arp
->ar_op
== htons(ARPOP_REQUEST
) && tip
== sip
&&
833 addr_type
== RTN_UNICAST
;
836 ((arp
->ar_op
== htons(ARPOP_REPLY
) &&
837 addr_type
== RTN_UNICAST
) || is_garp
))
838 n
= __neigh_lookup(&arp_tbl
, &sip
, dev
, 1);
842 int state
= NUD_REACHABLE
;
845 /* If several different ARP replies follows back-to-back,
846 use the FIRST one. It is possible, if several proxy
847 agents are active. Taking the first reply prevents
848 arp trashing and chooses the fastest router.
850 override
= time_after(jiffies
,
852 NEIGH_VAR(n
->parms
, LOCKTIME
)) ||
855 /* Broadcast replies and request packets
856 do not assert neighbour reachability.
858 if (arp
->ar_op
!= htons(ARPOP_REPLY
) ||
859 skb
->pkt_type
!= PACKET_HOST
)
861 neigh_update(n
, sha
, state
,
862 override
? NEIGH_UPDATE_F_OVERRIDE
: 0);
869 dst_release(reply_dst
);
873 static void parp_redo(struct sk_buff
*skb
)
875 arp_process(NULL
, skb
);
880 * Receive an arp request from the device layer.
883 static int arp_rcv(struct sk_buff
*skb
, struct net_device
*dev
,
884 struct packet_type
*pt
, struct net_device
*orig_dev
)
886 const struct arphdr
*arp
;
888 /* do not tweak dropwatch on an ARP we will ignore */
889 if (dev
->flags
& IFF_NOARP
||
890 skb
->pkt_type
== PACKET_OTHERHOST
||
891 skb
->pkt_type
== PACKET_LOOPBACK
)
894 skb
= skb_share_check(skb
, GFP_ATOMIC
);
898 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
899 if (!pskb_may_pull(skb
, arp_hdr_len(dev
)))
903 if (arp
->ar_hln
!= dev
->addr_len
|| arp
->ar_pln
!= 4)
906 memset(NEIGH_CB(skb
), 0, sizeof(struct neighbour_cb
));
908 return NF_HOOK(NFPROTO_ARP
, NF_ARP_IN
, NULL
, skb
,
909 dev
, NULL
, arp_process
);
921 * User level interface (ioctl)
925 * Set (create) an ARP cache entry.
928 static int arp_req_set_proxy(struct net
*net
, struct net_device
*dev
, int on
)
931 IPV4_DEVCONF_ALL(net
, PROXY_ARP
) = on
;
934 if (__in_dev_get_rtnl(dev
)) {
935 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev
), PROXY_ARP
, on
);
941 static int arp_req_set_public(struct net
*net
, struct arpreq
*r
,
942 struct net_device
*dev
)
944 __be32 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
945 __be32 mask
= ((struct sockaddr_in
*)&r
->arp_netmask
)->sin_addr
.s_addr
;
947 if (mask
&& mask
!= htonl(0xFFFFFFFF))
949 if (!dev
&& (r
->arp_flags
& ATF_COM
)) {
950 dev
= dev_getbyhwaddr_rcu(net
, r
->arp_ha
.sa_family
,
956 if (!pneigh_lookup(&arp_tbl
, net
, &ip
, dev
, 1))
961 return arp_req_set_proxy(net
, dev
, 1);
964 static int arp_req_set(struct net
*net
, struct arpreq
*r
,
965 struct net_device
*dev
)
968 struct neighbour
*neigh
;
971 if (r
->arp_flags
& ATF_PUBL
)
972 return arp_req_set_public(net
, r
, dev
);
974 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
975 if (r
->arp_flags
& ATF_PERM
)
976 r
->arp_flags
|= ATF_COM
;
978 struct rtable
*rt
= ip_route_output(net
, ip
, 0, RTO_ONLINK
, 0);
988 #if IS_ENABLED(CONFIG_FDDI)
991 * According to RFC 1390, FDDI devices should accept ARP
992 * hardware types of 1 (Ethernet). However, to be more
993 * robust, we'll accept hardware types of either 1 (Ethernet)
996 if (r
->arp_ha
.sa_family
!= ARPHRD_FDDI
&&
997 r
->arp_ha
.sa_family
!= ARPHRD_ETHER
&&
998 r
->arp_ha
.sa_family
!= ARPHRD_IEEE802
)
1003 if (r
->arp_ha
.sa_family
!= dev
->type
)
1008 neigh
= __neigh_lookup_errno(&arp_tbl
, &ip
, dev
);
1009 err
= PTR_ERR(neigh
);
1010 if (!IS_ERR(neigh
)) {
1011 unsigned int state
= NUD_STALE
;
1012 if (r
->arp_flags
& ATF_PERM
)
1013 state
= NUD_PERMANENT
;
1014 err
= neigh_update(neigh
, (r
->arp_flags
& ATF_COM
) ?
1015 r
->arp_ha
.sa_data
: NULL
, state
,
1016 NEIGH_UPDATE_F_OVERRIDE
|
1017 NEIGH_UPDATE_F_ADMIN
);
1018 neigh_release(neigh
);
1023 static unsigned int arp_state_to_flags(struct neighbour
*neigh
)
1025 if (neigh
->nud_state
&NUD_PERMANENT
)
1026 return ATF_PERM
| ATF_COM
;
1027 else if (neigh
->nud_state
&NUD_VALID
)
1034 * Get an ARP cache entry.
1037 static int arp_req_get(struct arpreq
*r
, struct net_device
*dev
)
1039 __be32 ip
= ((struct sockaddr_in
*) &r
->arp_pa
)->sin_addr
.s_addr
;
1040 struct neighbour
*neigh
;
1043 neigh
= neigh_lookup(&arp_tbl
, &ip
, dev
);
1045 if (!(neigh
->nud_state
& NUD_NOARP
)) {
1046 read_lock_bh(&neigh
->lock
);
1047 memcpy(r
->arp_ha
.sa_data
, neigh
->ha
, dev
->addr_len
);
1048 r
->arp_flags
= arp_state_to_flags(neigh
);
1049 read_unlock_bh(&neigh
->lock
);
1050 r
->arp_ha
.sa_family
= dev
->type
;
1051 strlcpy(r
->arp_dev
, dev
->name
, sizeof(r
->arp_dev
));
1054 neigh_release(neigh
);
1059 static int arp_invalidate(struct net_device
*dev
, __be32 ip
)
1061 struct neighbour
*neigh
= neigh_lookup(&arp_tbl
, &ip
, dev
);
1065 if (neigh
->nud_state
& ~NUD_NOARP
)
1066 err
= neigh_update(neigh
, NULL
, NUD_FAILED
,
1067 NEIGH_UPDATE_F_OVERRIDE
|
1068 NEIGH_UPDATE_F_ADMIN
);
1069 neigh_release(neigh
);
1075 static int arp_req_delete_public(struct net
*net
, struct arpreq
*r
,
1076 struct net_device
*dev
)
1078 __be32 ip
= ((struct sockaddr_in
*) &r
->arp_pa
)->sin_addr
.s_addr
;
1079 __be32 mask
= ((struct sockaddr_in
*)&r
->arp_netmask
)->sin_addr
.s_addr
;
1081 if (mask
== htonl(0xFFFFFFFF))
1082 return pneigh_delete(&arp_tbl
, net
, &ip
, dev
);
1087 return arp_req_set_proxy(net
, dev
, 0);
1090 static int arp_req_delete(struct net
*net
, struct arpreq
*r
,
1091 struct net_device
*dev
)
1095 if (r
->arp_flags
& ATF_PUBL
)
1096 return arp_req_delete_public(net
, r
, dev
);
1098 ip
= ((struct sockaddr_in
*)&r
->arp_pa
)->sin_addr
.s_addr
;
1100 struct rtable
*rt
= ip_route_output(net
, ip
, 0, RTO_ONLINK
, 0);
1108 return arp_invalidate(dev
, ip
);
1112 * Handle an ARP layer I/O control request.
1115 int arp_ioctl(struct net
*net
, unsigned int cmd
, void __user
*arg
)
1119 struct net_device
*dev
= NULL
;
1124 if (!ns_capable(net
->user_ns
, CAP_NET_ADMIN
))
1127 err
= copy_from_user(&r
, arg
, sizeof(struct arpreq
));
1135 if (r
.arp_pa
.sa_family
!= AF_INET
)
1136 return -EPFNOSUPPORT
;
1138 if (!(r
.arp_flags
& ATF_PUBL
) &&
1139 (r
.arp_flags
& (ATF_NETMASK
| ATF_DONTPUB
)))
1141 if (!(r
.arp_flags
& ATF_NETMASK
))
1142 ((struct sockaddr_in
*)&r
.arp_netmask
)->sin_addr
.s_addr
=
1143 htonl(0xFFFFFFFFUL
);
1147 dev
= __dev_get_by_name(net
, r
.arp_dev
);
1151 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1152 if (!r
.arp_ha
.sa_family
)
1153 r
.arp_ha
.sa_family
= dev
->type
;
1155 if ((r
.arp_flags
& ATF_COM
) && r
.arp_ha
.sa_family
!= dev
->type
)
1157 } else if (cmd
== SIOCGARP
) {
1164 err
= arp_req_delete(net
, &r
, dev
);
1167 err
= arp_req_set(net
, &r
, dev
);
1170 err
= arp_req_get(&r
, dev
);
1175 if (cmd
== SIOCGARP
&& !err
&& copy_to_user(arg
, &r
, sizeof(r
)))
1180 static int arp_netdev_event(struct notifier_block
*this, unsigned long event
,
1183 struct net_device
*dev
= netdev_notifier_info_to_dev(ptr
);
1184 struct netdev_notifier_change_info
*change_info
;
1187 case NETDEV_CHANGEADDR
:
1188 neigh_changeaddr(&arp_tbl
, dev
);
1189 rt_cache_flush(dev_net(dev
));
1193 if (change_info
->flags_changed
& IFF_NOARP
)
1194 neigh_changeaddr(&arp_tbl
, dev
);
1203 static struct notifier_block arp_netdev_notifier
= {
1204 .notifier_call
= arp_netdev_event
,
1207 /* Note, that it is not on notifier chain.
1208 It is necessary, that this routine was called after route cache will be
1211 void arp_ifdown(struct net_device
*dev
)
1213 neigh_ifdown(&arp_tbl
, dev
);
1218 * Called once on startup.
1221 static struct packet_type arp_packet_type __read_mostly
= {
1222 .type
= cpu_to_be16(ETH_P_ARP
),
1226 static int arp_proc_init(void);
1228 void __init
arp_init(void)
1230 neigh_table_init(NEIGH_ARP_TABLE
, &arp_tbl
);
1232 dev_add_pack(&arp_packet_type
);
1234 #ifdef CONFIG_SYSCTL
1235 neigh_sysctl_register(NULL
, &arp_tbl
.parms
, NULL
);
1237 register_netdevice_notifier(&arp_netdev_notifier
);
1240 #ifdef CONFIG_PROC_FS
1241 #if IS_ENABLED(CONFIG_AX25)
1243 /* ------------------------------------------------------------------------ */
1245 * ax25 -> ASCII conversion
1247 static char *ax2asc2(ax25_address
*a
, char *buf
)
1252 for (n
= 0, s
= buf
; n
< 6; n
++) {
1253 c
= (a
->ax25_call
[n
] >> 1) & 0x7F;
1260 n
= (a
->ax25_call
[6] >> 1) & 0x0F;
1269 if (*buf
== '\0' || *buf
== '-')
1274 #endif /* CONFIG_AX25 */
1276 #define HBUFFERLEN 30
1278 static void arp_format_neigh_entry(struct seq_file
*seq
,
1279 struct neighbour
*n
)
1281 char hbuffer
[HBUFFERLEN
];
1284 struct net_device
*dev
= n
->dev
;
1285 int hatype
= dev
->type
;
1287 read_lock(&n
->lock
);
1288 /* Convert hardware address to XX:XX:XX:XX ... form. */
1289 #if IS_ENABLED(CONFIG_AX25)
1290 if (hatype
== ARPHRD_AX25
|| hatype
== ARPHRD_NETROM
)
1291 ax2asc2((ax25_address
*)n
->ha
, hbuffer
);
1294 for (k
= 0, j
= 0; k
< HBUFFERLEN
- 3 && j
< dev
->addr_len
; j
++) {
1295 hbuffer
[k
++] = hex_asc_hi(n
->ha
[j
]);
1296 hbuffer
[k
++] = hex_asc_lo(n
->ha
[j
]);
1302 #if IS_ENABLED(CONFIG_AX25)
1305 sprintf(tbuf
, "%pI4", n
->primary_key
);
1306 seq_printf(seq
, "%-16s 0x%-10x0x%-10x%s * %s\n",
1307 tbuf
, hatype
, arp_state_to_flags(n
), hbuffer
, dev
->name
);
1308 read_unlock(&n
->lock
);
1311 static void arp_format_pneigh_entry(struct seq_file
*seq
,
1312 struct pneigh_entry
*n
)
1314 struct net_device
*dev
= n
->dev
;
1315 int hatype
= dev
? dev
->type
: 0;
1318 sprintf(tbuf
, "%pI4", n
->key
);
1319 seq_printf(seq
, "%-16s 0x%-10x0x%-10x%s * %s\n",
1320 tbuf
, hatype
, ATF_PUBL
| ATF_PERM
, "00:00:00:00:00:00",
1321 dev
? dev
->name
: "*");
1324 static int arp_seq_show(struct seq_file
*seq
, void *v
)
1326 if (v
== SEQ_START_TOKEN
) {
1327 seq_puts(seq
, "IP address HW type Flags "
1328 "HW address Mask Device\n");
1330 struct neigh_seq_state
*state
= seq
->private;
1332 if (state
->flags
& NEIGH_SEQ_IS_PNEIGH
)
1333 arp_format_pneigh_entry(seq
, v
);
1335 arp_format_neigh_entry(seq
, v
);
1341 static void *arp_seq_start(struct seq_file
*seq
, loff_t
*pos
)
1343 /* Don't want to confuse "arp -a" w/ magic entries,
1344 * so we tell the generic iterator to skip NUD_NOARP.
1346 return neigh_seq_start(seq
, pos
, &arp_tbl
, NEIGH_SEQ_SKIP_NOARP
);
1349 /* ------------------------------------------------------------------------ */
1351 static const struct seq_operations arp_seq_ops
= {
1352 .start
= arp_seq_start
,
1353 .next
= neigh_seq_next
,
1354 .stop
= neigh_seq_stop
,
1355 .show
= arp_seq_show
,
1358 static int arp_seq_open(struct inode
*inode
, struct file
*file
)
1360 return seq_open_net(inode
, file
, &arp_seq_ops
,
1361 sizeof(struct neigh_seq_state
));
1364 static const struct file_operations arp_seq_fops
= {
1365 .owner
= THIS_MODULE
,
1366 .open
= arp_seq_open
,
1368 .llseek
= seq_lseek
,
1369 .release
= seq_release_net
,
1373 static int __net_init
arp_net_init(struct net
*net
)
1375 if (!proc_create("arp", S_IRUGO
, net
->proc_net
, &arp_seq_fops
))
1380 static void __net_exit
arp_net_exit(struct net
*net
)
1382 remove_proc_entry("arp", net
->proc_net
);
1385 static struct pernet_operations arp_net_ops
= {
1386 .init
= arp_net_init
,
1387 .exit
= arp_net_exit
,
1390 static int __init
arp_proc_init(void)
1392 return register_pernet_subsys(&arp_net_ops
);
1395 #else /* CONFIG_PROC_FS */
1397 static int __init
arp_proc_init(void)
1402 #endif /* CONFIG_PROC_FS */