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1/* linux/net/ipv4/arp.c
2 *
3 * Copyright (C) 1994 by Florian La Roche
4 *
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
8 * address).
9 *
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.
14 *
15 * Fixes:
16 * Alan Cox : Removed the Ethernet assumptions in
17 * Florian's code
18 * Alan Cox : Fixed some small errors in the ARP
19 * logic
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
41 * during arp_rcv.
42 * Russ Nelson : Tidied up a few bits.
43 * Alexey Kuznetsov: Major changes to caching and behaviour,
44 * eg intelligent arp probing and
45 * generation
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
61 * one in...
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.
74 */
75
76#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
77
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>
86#include <linux/in.h>
87#include <linux/mm.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>
102#ifdef CONFIG_SYSCTL
103#include <linux/sysctl.h>
104#endif
105
106#include <net/net_namespace.h>
107#include <net/ip.h>
108#include <net/icmp.h>
109#include <net/route.h>
110#include <net/protocol.h>
111#include <net/tcp.h>
112#include <net/sock.h>
113#include <net/arp.h>
114#include <net/ax25.h>
115#include <net/netrom.h>
116#include <net/dst_metadata.h>
117#include <net/ip_tunnels.h>
118
119#include <linux/uaccess.h>
120
121#include <linux/netfilter_arp.h>
122
123/*
124 * Interface to generic neighbour cache.
125 */
126static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd);
127static bool arp_key_eq(const struct neighbour *n, const void *pkey);
128static int arp_constructor(struct neighbour *neigh);
129static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
130static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
131static void parp_redo(struct sk_buff *skb);
132
133static const struct neigh_ops arp_generic_ops = {
134 .family = AF_INET,
135 .solicit = arp_solicit,
136 .error_report = arp_error_report,
137 .output = neigh_resolve_output,
138 .connected_output = neigh_connected_output,
139};
140
141static const struct neigh_ops arp_hh_ops = {
142 .family = AF_INET,
143 .solicit = arp_solicit,
144 .error_report = arp_error_report,
145 .output = neigh_resolve_output,
146 .connected_output = neigh_resolve_output,
147};
148
149static const struct neigh_ops arp_direct_ops = {
150 .family = AF_INET,
151 .output = neigh_direct_output,
152 .connected_output = neigh_direct_output,
153};
154
155struct neigh_table arp_tbl = {
156 .family = AF_INET,
157 .key_len = 4,
158 .protocol = cpu_to_be16(ETH_P_IP),
159 .hash = arp_hash,
160 .key_eq = arp_key_eq,
161 .constructor = arp_constructor,
162 .proxy_redo = parp_redo,
163 .id = "arp_cache",
164 .parms = {
165 .tbl = &arp_tbl,
166 .reachable_time = 30 * HZ,
167 .data = {
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,
179 },
180 },
181 .gc_interval = 30 * HZ,
182 .gc_thresh1 = 128,
183 .gc_thresh2 = 512,
184 .gc_thresh3 = 1024,
185};
186EXPORT_SYMBOL(arp_tbl);
187
188int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir)
189{
190 switch (dev->type) {
191 case ARPHRD_ETHER:
192 case ARPHRD_FDDI:
193 case ARPHRD_IEEE802:
194 ip_eth_mc_map(addr, haddr);
195 return 0;
196 case ARPHRD_INFINIBAND:
197 ip_ib_mc_map(addr, dev->broadcast, haddr);
198 return 0;
199 case ARPHRD_IPGRE:
200 ip_ipgre_mc_map(addr, dev->broadcast, haddr);
201 return 0;
202 default:
203 if (dir) {
204 memcpy(haddr, dev->broadcast, dev->addr_len);
205 return 0;
206 }
207 }
208 return -EINVAL;
209}
210
211
212static u32 arp_hash(const void *pkey,
213 const struct net_device *dev,
214 __u32 *hash_rnd)
215{
216 return arp_hashfn(pkey, dev, hash_rnd);
217}
218
219static bool arp_key_eq(const struct neighbour *neigh, const void *pkey)
220{
221 return neigh_key_eq32(neigh, pkey);
222}
223
224static int arp_constructor(struct neighbour *neigh)
225{
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;
230
231 rcu_read_lock();
232 in_dev = __in_dev_get_rcu(dev);
233 if (!in_dev) {
234 rcu_read_unlock();
235 return -EINVAL;
236 }
237
238 neigh->type = inet_addr_type_dev_table(dev_net(dev), dev, addr);
239
240 parms = in_dev->arp_parms;
241 __neigh_parms_put(neigh->parms);
242 neigh->parms = neigh_parms_clone(parms);
243 rcu_read_unlock();
244
245 if (!dev->header_ops) {
246 neigh->nud_state = NUD_NOARP;
247 neigh->ops = &arp_direct_ops;
248 neigh->output = neigh_direct_output;
249 } else {
250 /* Good devices (checked by reading texts, but only Ethernet is
251 tested)
252
253 ARPHRD_ETHER: (ethernet, apfddi)
254 ARPHRD_FDDI: (fddi)
255 ARPHRD_IEEE802: (tr)
256 ARPHRD_METRICOM: (strip)
257 ARPHRD_ARCNET:
258 etc. etc. etc.
259
260 ARPHRD_IPDDP will also work, if author repairs it.
261 I did not it, because this driver does not work even
262 in old paradigm.
263 */
264
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);
275 }
276
277 if (dev->header_ops->cache)
278 neigh->ops = &arp_hh_ops;
279 else
280 neigh->ops = &arp_generic_ops;
281
282 if (neigh->nud_state & NUD_VALID)
283 neigh->output = neigh->ops->connected_output;
284 else
285 neigh->output = neigh->ops->output;
286 }
287 return 0;
288}
289
290static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
291{
292 dst_link_failure(skb);
293 kfree_skb(skb);
294}
295
296/* Create and send an arp packet. */
297static 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)
303{
304 struct sk_buff *skb;
305
306 /* arp on this interface. */
307 if (dev->flags & IFF_NOARP)
308 return;
309
310 skb = arp_create(type, ptype, dest_ip, dev, src_ip,
311 dest_hw, src_hw, target_hw);
312 if (!skb)
313 return;
314
315 skb_dst_set(skb, dst_clone(dst));
316 arp_xmit(skb);
317}
318
319void 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)
323{
324 arp_send_dst(type, ptype, dest_ip, dev, src_ip, dest_hw, src_hw,
325 target_hw, NULL);
326}
327EXPORT_SYMBOL(arp_send);
328
329static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
330{
331 __be32 saddr = 0;
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;
338
339 rcu_read_lock();
340 in_dev = __in_dev_get_rcu(dev);
341 if (!in_dev) {
342 rcu_read_unlock();
343 return;
344 }
345 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
346 default:
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;
351 break;
352 case 1: /* Restrict announcements of saddr in same subnet */
353 if (!skb)
354 break;
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))
360 break;
361 }
362 saddr = 0;
363 break;
364 case 2: /* Avoid secondary IPs, get a primary/preferred one */
365 break;
366 }
367 rcu_read_unlock();
368
369 if (!saddr)
370 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
371
372 probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES);
373 if (probes < 0) {
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);
377 dst_hw = dst_ha;
378 } else {
379 probes -= NEIGH_VAR(neigh->parms, APP_PROBES);
380 if (probes < 0) {
381 neigh_app_ns(neigh);
382 return;
383 }
384 }
385
386 if (skb && !(dev->priv_flags & IFF_XMIT_DST_RELEASE))
387 dst = skb_dst(skb);
388 arp_send_dst(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
389 dst_hw, dev->dev_addr, NULL, dst);
390}
391
392static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip)
393{
394 struct net *net = dev_net(in_dev->dev);
395 int scope;
396
397 switch (IN_DEV_ARP_IGNORE(in_dev)) {
398 case 0: /* Reply, the tip is already validated */
399 return 0;
400 case 1: /* Reply only if tip is configured on the incoming interface */
401 sip = 0;
402 scope = RT_SCOPE_HOST;
403 break;
404 case 2: /*
405 * Reply only if tip is configured on the incoming interface
406 * and is in same subnet as sip
407 */
408 scope = RT_SCOPE_HOST;
409 break;
410 case 3: /* Do not reply for scope host addresses */
411 sip = 0;
412 scope = RT_SCOPE_LINK;
413 in_dev = NULL;
414 break;
415 case 4: /* Reserved */
416 case 5:
417 case 6:
418 case 7:
419 return 0;
420 case 8: /* Do not reply */
421 return 1;
422 default:
423 return 0;
424 }
425 return !inet_confirm_addr(net, in_dev, sip, tip, scope);
426}
427
428static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
429{
430 struct rtable *rt;
431 int flag = 0;
432 /*unsigned long now; */
433 struct net *net = dev_net(dev);
434
435 rt = ip_route_output(net, sip, tip, 0, 0);
436 if (IS_ERR(rt))
437 return 1;
438 if (rt->dst.dev != dev) {
439 NET_INC_STATS_BH(net, LINUX_MIB_ARPFILTER);
440 flag = 1;
441 }
442 ip_rt_put(rt);
443 return flag;
444}
445
446/*
447 * Check if we can use proxy ARP for this path
448 */
449static inline int arp_fwd_proxy(struct in_device *in_dev,
450 struct net_device *dev, struct rtable *rt)
451{
452 struct in_device *out_dev;
453 int imi, omi = -1;
454
455 if (rt->dst.dev == dev)
456 return 0;
457
458 if (!IN_DEV_PROXY_ARP(in_dev))
459 return 0;
460 imi = IN_DEV_MEDIUM_ID(in_dev);
461 if (imi == 0)
462 return 1;
463 if (imi == -1)
464 return 0;
465
466 /* place to check for proxy_arp for routes */
467
468 out_dev = __in_dev_get_rcu(rt->dst.dev);
469 if (out_dev)
470 omi = IN_DEV_MEDIUM_ID(out_dev);
471
472 return omi != imi && omi != -1;
473}
474
475/*
476 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
477 *
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.
484 *
485 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
486 *
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).
492 *
493 */
494static inline int arp_fwd_pvlan(struct in_device *in_dev,
495 struct net_device *dev, struct rtable *rt,
496 __be32 sip, __be32 tip)
497{
498 /* Private VLAN is only concerned about the same ethernet segment */
499 if (rt->dst.dev != dev)
500 return 0;
501
502 /* Don't reply on self probes (often done by windowz boxes)*/
503 if (sip == tip)
504 return 0;
505
506 if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
507 return 1;
508 else
509 return 0;
510}
511
512/*
513 * Interface to link layer: send routine and receive handler.
514 */
515
516/*
517 * Create an arp packet. If dest_hw is not set, we create a broadcast
518 * message.
519 */
520struct 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)
525{
526 struct sk_buff *skb;
527 struct arphdr *arp;
528 unsigned char *arp_ptr;
529 int hlen = LL_RESERVED_SPACE(dev);
530 int tlen = dev->needed_tailroom;
531
532 /*
533 * Allocate a buffer
534 */
535
536 skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
537 if (!skb)
538 return NULL;
539
540 skb_reserve(skb, hlen);
541 skb_reset_network_header(skb);
542 arp = (struct arphdr *) skb_put(skb, arp_hdr_len(dev));
543 skb->dev = dev;
544 skb->protocol = htons(ETH_P_ARP);
545 if (!src_hw)
546 src_hw = dev->dev_addr;
547 if (!dest_hw)
548 dest_hw = dev->broadcast;
549
550 /*
551 * Fill the device header for the ARP frame
552 */
553 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
554 goto out;
555
556 /*
557 * Fill out the arp protocol part.
558 *
559 * The arp hardware type should match the device type, except for FDDI,
560 * which (according to RFC 1390) should always equal 1 (Ethernet).
561 */
562 /*
563 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
564 * DIX code for the protocol. Make these device structure fields.
565 */
566 switch (dev->type) {
567 default:
568 arp->ar_hrd = htons(dev->type);
569 arp->ar_pro = htons(ETH_P_IP);
570 break;
571
572#if IS_ENABLED(CONFIG_AX25)
573 case ARPHRD_AX25:
574 arp->ar_hrd = htons(ARPHRD_AX25);
575 arp->ar_pro = htons(AX25_P_IP);
576 break;
577
578#if IS_ENABLED(CONFIG_NETROM)
579 case ARPHRD_NETROM:
580 arp->ar_hrd = htons(ARPHRD_NETROM);
581 arp->ar_pro = htons(AX25_P_IP);
582 break;
583#endif
584#endif
585
586#if IS_ENABLED(CONFIG_FDDI)
587 case ARPHRD_FDDI:
588 arp->ar_hrd = htons(ARPHRD_ETHER);
589 arp->ar_pro = htons(ETH_P_IP);
590 break;
591#endif
592 }
593
594 arp->ar_hln = dev->addr_len;
595 arp->ar_pln = 4;
596 arp->ar_op = htons(type);
597
598 arp_ptr = (unsigned char *)(arp + 1);
599
600 memcpy(arp_ptr, src_hw, dev->addr_len);
601 arp_ptr += dev->addr_len;
602 memcpy(arp_ptr, &src_ip, 4);
603 arp_ptr += 4;
604
605 switch (dev->type) {
606#if IS_ENABLED(CONFIG_FIREWIRE_NET)
607 case ARPHRD_IEEE1394:
608 break;
609#endif
610 default:
611 if (target_hw)
612 memcpy(arp_ptr, target_hw, dev->addr_len);
613 else
614 memset(arp_ptr, 0, dev->addr_len);
615 arp_ptr += dev->addr_len;
616 }
617 memcpy(arp_ptr, &dest_ip, 4);
618
619 return skb;
620
621out:
622 kfree_skb(skb);
623 return NULL;
624}
625EXPORT_SYMBOL(arp_create);
626
627static int arp_xmit_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
628{
629 return dev_queue_xmit(skb);
630}
631
632/*
633 * Send an arp packet.
634 */
635void arp_xmit(struct sk_buff *skb)
636{
637 /* Send it off, maybe filter it using firewalling first. */
638 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT,
639 dev_net(skb->dev), NULL, skb, NULL, skb->dev,
640 arp_xmit_finish);
641}
642EXPORT_SYMBOL(arp_xmit);
643
644/*
645 * Process an arp request.
646 */
647
648static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb)
649{
650 struct net_device *dev = skb->dev;
651 struct in_device *in_dev = __in_dev_get_rcu(dev);
652 struct arphdr *arp;
653 unsigned char *arp_ptr;
654 struct rtable *rt;
655 unsigned char *sha;
656 __be32 sip, tip;
657 u16 dev_type = dev->type;
658 int addr_type;
659 struct neighbour *n;
660 struct dst_entry *reply_dst = NULL;
661 bool is_garp = false;
662
663 /* arp_rcv below verifies the ARP header and verifies the device
664 * is ARP'able.
665 */
666
667 if (!in_dev)
668 goto out_free_skb;
669
670 arp = arp_hdr(skb);
671
672 switch (dev_type) {
673 default:
674 if (arp->ar_pro != htons(ETH_P_IP) ||
675 htons(dev_type) != arp->ar_hrd)
676 goto out_free_skb;
677 break;
678 case ARPHRD_ETHER:
679 case ARPHRD_FDDI:
680 case ARPHRD_IEEE802:
681 /*
682 * ETHERNET, and Fibre Channel (which are IEEE 802
683 * devices, according to RFC 2625) devices will accept ARP
684 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
685 * This is the case also of FDDI, where the RFC 1390 says that
686 * FDDI devices should accept ARP hardware of (1) Ethernet,
687 * however, to be more robust, we'll accept both 1 (Ethernet)
688 * or 6 (IEEE 802.2)
689 */
690 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
691 arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
692 arp->ar_pro != htons(ETH_P_IP))
693 goto out_free_skb;
694 break;
695 case ARPHRD_AX25:
696 if (arp->ar_pro != htons(AX25_P_IP) ||
697 arp->ar_hrd != htons(ARPHRD_AX25))
698 goto out_free_skb;
699 break;
700 case ARPHRD_NETROM:
701 if (arp->ar_pro != htons(AX25_P_IP) ||
702 arp->ar_hrd != htons(ARPHRD_NETROM))
703 goto out_free_skb;
704 break;
705 }
706
707 /* Understand only these message types */
708
709 if (arp->ar_op != htons(ARPOP_REPLY) &&
710 arp->ar_op != htons(ARPOP_REQUEST))
711 goto out_free_skb;
712
713/*
714 * Extract fields
715 */
716 arp_ptr = (unsigned char *)(arp + 1);
717 sha = arp_ptr;
718 arp_ptr += dev->addr_len;
719 memcpy(&sip, arp_ptr, 4);
720 arp_ptr += 4;
721 switch (dev_type) {
722#if IS_ENABLED(CONFIG_FIREWIRE_NET)
723 case ARPHRD_IEEE1394:
724 break;
725#endif
726 default:
727 arp_ptr += dev->addr_len;
728 }
729 memcpy(&tip, arp_ptr, 4);
730/*
731 * Check for bad requests for 127.x.x.x and requests for multicast
732 * addresses. If this is one such, delete it.
733 */
734 if (ipv4_is_multicast(tip) ||
735 (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip)))
736 goto out_free_skb;
737
738 /*
739 * For some 802.11 wireless deployments (and possibly other networks),
740 * there will be an ARP proxy and gratuitous ARP frames are attacks
741 * and thus should not be accepted.
742 */
743 if (sip == tip && IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP))
744 goto out_free_skb;
745
746/*
747 * Special case: We must set Frame Relay source Q.922 address
748 */
749 if (dev_type == ARPHRD_DLCI)
750 sha = dev->broadcast;
751
752/*
753 * Process entry. The idea here is we want to send a reply if it is a
754 * request for us or if it is a request for someone else that we hold
755 * a proxy for. We want to add an entry to our cache if it is a reply
756 * to us or if it is a request for our address.
757 * (The assumption for this last is that if someone is requesting our
758 * address, they are probably intending to talk to us, so it saves time
759 * if we cache their address. Their address is also probably not in
760 * our cache, since ours is not in their cache.)
761 *
762 * Putting this another way, we only care about replies if they are to
763 * us, in which case we add them to the cache. For requests, we care
764 * about those for us and those for our proxies. We reply to both,
765 * and in the case of requests for us we add the requester to the arp
766 * cache.
767 */
768
769 if (arp->ar_op == htons(ARPOP_REQUEST) && skb_metadata_dst(skb))
770 reply_dst = (struct dst_entry *)
771 iptunnel_metadata_reply(skb_metadata_dst(skb),
772 GFP_ATOMIC);
773
774 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
775 if (sip == 0) {
776 if (arp->ar_op == htons(ARPOP_REQUEST) &&
777 inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL &&
778 !arp_ignore(in_dev, sip, tip))
779 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip,
780 sha, dev->dev_addr, sha, reply_dst);
781 goto out_consume_skb;
782 }
783
784 if (arp->ar_op == htons(ARPOP_REQUEST) &&
785 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
786
787 rt = skb_rtable(skb);
788 addr_type = rt->rt_type;
789
790 if (addr_type == RTN_LOCAL) {
791 int dont_send;
792
793 dont_send = arp_ignore(in_dev, sip, tip);
794 if (!dont_send && IN_DEV_ARPFILTER(in_dev))
795 dont_send = arp_filter(sip, tip, dev);
796 if (!dont_send) {
797 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
798 if (n) {
799 arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
800 sip, dev, tip, sha,
801 dev->dev_addr, sha,
802 reply_dst);
803 neigh_release(n);
804 }
805 }
806 goto out_consume_skb;
807 } else if (IN_DEV_FORWARD(in_dev)) {
808 if (addr_type == RTN_UNICAST &&
809 (arp_fwd_proxy(in_dev, dev, rt) ||
810 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
811 (rt->dst.dev != dev &&
812 pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
813 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
814 if (n)
815 neigh_release(n);
816
817 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
818 skb->pkt_type == PACKET_HOST ||
819 NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) {
820 arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
821 sip, dev, tip, sha,
822 dev->dev_addr, sha,
823 reply_dst);
824 } else {
825 pneigh_enqueue(&arp_tbl,
826 in_dev->arp_parms, skb);
827 goto out_free_dst;
828 }
829 goto out_consume_skb;
830 }
831 }
832 }
833
834 /* Update our ARP tables */
835
836 n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
837
838 if (IN_DEV_ARP_ACCEPT(in_dev)) {
839 unsigned int addr_type = inet_addr_type_dev_table(net, dev, sip);
840
841 /* Unsolicited ARP is not accepted by default.
842 It is possible, that this option should be enabled for some
843 devices (strip is candidate)
844 */
845 is_garp = arp->ar_op == htons(ARPOP_REQUEST) && tip == sip &&
846 addr_type == RTN_UNICAST;
847
848 if (!n &&
849 ((arp->ar_op == htons(ARPOP_REPLY) &&
850 addr_type == RTN_UNICAST) || is_garp))
851 n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
852 }
853
854 if (n) {
855 int state = NUD_REACHABLE;
856 int override;
857
858 /* If several different ARP replies follows back-to-back,
859 use the FIRST one. It is possible, if several proxy
860 agents are active. Taking the first reply prevents
861 arp trashing and chooses the fastest router.
862 */
863 override = time_after(jiffies,
864 n->updated +
865 NEIGH_VAR(n->parms, LOCKTIME)) ||
866 is_garp;
867
868 /* Broadcast replies and request packets
869 do not assert neighbour reachability.
870 */
871 if (arp->ar_op != htons(ARPOP_REPLY) ||
872 skb->pkt_type != PACKET_HOST)
873 state = NUD_STALE;
874 neigh_update(n, sha, state,
875 override ? NEIGH_UPDATE_F_OVERRIDE : 0);
876 neigh_release(n);
877 }
878
879out_consume_skb:
880 consume_skb(skb);
881
882out_free_dst:
883 dst_release(reply_dst);
884 return NET_RX_SUCCESS;
885
886out_free_skb:
887 kfree_skb(skb);
888 return NET_RX_DROP;
889}
890
891static void parp_redo(struct sk_buff *skb)
892{
893 arp_process(dev_net(skb->dev), NULL, skb);
894}
895
896
897/*
898 * Receive an arp request from the device layer.
899 */
900
901static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
902 struct packet_type *pt, struct net_device *orig_dev)
903{
904 const struct arphdr *arp;
905
906 /* do not tweak dropwatch on an ARP we will ignore */
907 if (dev->flags & IFF_NOARP ||
908 skb->pkt_type == PACKET_OTHERHOST ||
909 skb->pkt_type == PACKET_LOOPBACK)
910 goto consumeskb;
911
912 skb = skb_share_check(skb, GFP_ATOMIC);
913 if (!skb)
914 goto out_of_mem;
915
916 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
917 if (!pskb_may_pull(skb, arp_hdr_len(dev)))
918 goto freeskb;
919
920 arp = arp_hdr(skb);
921 if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4)
922 goto freeskb;
923
924 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
925
926 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN,
927 dev_net(dev), NULL, skb, dev, NULL,
928 arp_process);
929
930consumeskb:
931 consume_skb(skb);
932 return NET_RX_SUCCESS;
933freeskb:
934 kfree_skb(skb);
935out_of_mem:
936 return NET_RX_DROP;
937}
938
939/*
940 * User level interface (ioctl)
941 */
942
943/*
944 * Set (create) an ARP cache entry.
945 */
946
947static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
948{
949 if (!dev) {
950 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
951 return 0;
952 }
953 if (__in_dev_get_rtnl(dev)) {
954 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
955 return 0;
956 }
957 return -ENXIO;
958}
959
960static int arp_req_set_public(struct net *net, struct arpreq *r,
961 struct net_device *dev)
962{
963 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
964 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
965
966 if (mask && mask != htonl(0xFFFFFFFF))
967 return -EINVAL;
968 if (!dev && (r->arp_flags & ATF_COM)) {
969 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family,
970 r->arp_ha.sa_data);
971 if (!dev)
972 return -ENODEV;
973 }
974 if (mask) {
975 if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1))
976 return -ENOBUFS;
977 return 0;
978 }
979
980 return arp_req_set_proxy(net, dev, 1);
981}
982
983static int arp_req_set(struct net *net, struct arpreq *r,
984 struct net_device *dev)
985{
986 __be32 ip;
987 struct neighbour *neigh;
988 int err;
989
990 if (r->arp_flags & ATF_PUBL)
991 return arp_req_set_public(net, r, dev);
992
993 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
994 if (r->arp_flags & ATF_PERM)
995 r->arp_flags |= ATF_COM;
996 if (!dev) {
997 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
998
999 if (IS_ERR(rt))
1000 return PTR_ERR(rt);
1001 dev = rt->dst.dev;
1002 ip_rt_put(rt);
1003 if (!dev)
1004 return -EINVAL;
1005 }
1006 switch (dev->type) {
1007#if IS_ENABLED(CONFIG_FDDI)
1008 case ARPHRD_FDDI:
1009 /*
1010 * According to RFC 1390, FDDI devices should accept ARP
1011 * hardware types of 1 (Ethernet). However, to be more
1012 * robust, we'll accept hardware types of either 1 (Ethernet)
1013 * or 6 (IEEE 802.2).
1014 */
1015 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1016 r->arp_ha.sa_family != ARPHRD_ETHER &&
1017 r->arp_ha.sa_family != ARPHRD_IEEE802)
1018 return -EINVAL;
1019 break;
1020#endif
1021 default:
1022 if (r->arp_ha.sa_family != dev->type)
1023 return -EINVAL;
1024 break;
1025 }
1026
1027 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1028 err = PTR_ERR(neigh);
1029 if (!IS_ERR(neigh)) {
1030 unsigned int state = NUD_STALE;
1031 if (r->arp_flags & ATF_PERM)
1032 state = NUD_PERMANENT;
1033 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ?
1034 r->arp_ha.sa_data : NULL, state,
1035 NEIGH_UPDATE_F_OVERRIDE |
1036 NEIGH_UPDATE_F_ADMIN);
1037 neigh_release(neigh);
1038 }
1039 return err;
1040}
1041
1042static unsigned int arp_state_to_flags(struct neighbour *neigh)
1043{
1044 if (neigh->nud_state&NUD_PERMANENT)
1045 return ATF_PERM | ATF_COM;
1046 else if (neigh->nud_state&NUD_VALID)
1047 return ATF_COM;
1048 else
1049 return 0;
1050}
1051
1052/*
1053 * Get an ARP cache entry.
1054 */
1055
1056static int arp_req_get(struct arpreq *r, struct net_device *dev)
1057{
1058 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1059 struct neighbour *neigh;
1060 int err = -ENXIO;
1061
1062 neigh = neigh_lookup(&arp_tbl, &ip, dev);
1063 if (neigh) {
1064 if (!(neigh->nud_state & NUD_NOARP)) {
1065 read_lock_bh(&neigh->lock);
1066 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
1067 r->arp_flags = arp_state_to_flags(neigh);
1068 read_unlock_bh(&neigh->lock);
1069 r->arp_ha.sa_family = dev->type;
1070 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1071 err = 0;
1072 }
1073 neigh_release(neigh);
1074 }
1075 return err;
1076}
1077
1078static int arp_invalidate(struct net_device *dev, __be32 ip)
1079{
1080 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
1081 int err = -ENXIO;
1082
1083 if (neigh) {
1084 if (neigh->nud_state & ~NUD_NOARP)
1085 err = neigh_update(neigh, NULL, NUD_FAILED,
1086 NEIGH_UPDATE_F_OVERRIDE|
1087 NEIGH_UPDATE_F_ADMIN);
1088 neigh_release(neigh);
1089 }
1090
1091 return err;
1092}
1093
1094static int arp_req_delete_public(struct net *net, struct arpreq *r,
1095 struct net_device *dev)
1096{
1097 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1098 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1099
1100 if (mask == htonl(0xFFFFFFFF))
1101 return pneigh_delete(&arp_tbl, net, &ip, dev);
1102
1103 if (mask)
1104 return -EINVAL;
1105
1106 return arp_req_set_proxy(net, dev, 0);
1107}
1108
1109static int arp_req_delete(struct net *net, struct arpreq *r,
1110 struct net_device *dev)
1111{
1112 __be32 ip;
1113
1114 if (r->arp_flags & ATF_PUBL)
1115 return arp_req_delete_public(net, r, dev);
1116
1117 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1118 if (!dev) {
1119 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1120 if (IS_ERR(rt))
1121 return PTR_ERR(rt);
1122 dev = rt->dst.dev;
1123 ip_rt_put(rt);
1124 if (!dev)
1125 return -EINVAL;
1126 }
1127 return arp_invalidate(dev, ip);
1128}
1129
1130/*
1131 * Handle an ARP layer I/O control request.
1132 */
1133
1134int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1135{
1136 int err;
1137 struct arpreq r;
1138 struct net_device *dev = NULL;
1139
1140 switch (cmd) {
1141 case SIOCDARP:
1142 case SIOCSARP:
1143 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1144 return -EPERM;
1145 case SIOCGARP:
1146 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1147 if (err)
1148 return -EFAULT;
1149 break;
1150 default:
1151 return -EINVAL;
1152 }
1153
1154 if (r.arp_pa.sa_family != AF_INET)
1155 return -EPFNOSUPPORT;
1156
1157 if (!(r.arp_flags & ATF_PUBL) &&
1158 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1159 return -EINVAL;
1160 if (!(r.arp_flags & ATF_NETMASK))
1161 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1162 htonl(0xFFFFFFFFUL);
1163 rtnl_lock();
1164 if (r.arp_dev[0]) {
1165 err = -ENODEV;
1166 dev = __dev_get_by_name(net, r.arp_dev);
1167 if (!dev)
1168 goto out;
1169
1170 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1171 if (!r.arp_ha.sa_family)
1172 r.arp_ha.sa_family = dev->type;
1173 err = -EINVAL;
1174 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1175 goto out;
1176 } else if (cmd == SIOCGARP) {
1177 err = -ENODEV;
1178 goto out;
1179 }
1180
1181 switch (cmd) {
1182 case SIOCDARP:
1183 err = arp_req_delete(net, &r, dev);
1184 break;
1185 case SIOCSARP:
1186 err = arp_req_set(net, &r, dev);
1187 break;
1188 case SIOCGARP:
1189 err = arp_req_get(&r, dev);
1190 break;
1191 }
1192out:
1193 rtnl_unlock();
1194 if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
1195 err = -EFAULT;
1196 return err;
1197}
1198
1199static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1200 void *ptr)
1201{
1202 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
1203 struct netdev_notifier_change_info *change_info;
1204
1205 switch (event) {
1206 case NETDEV_CHANGEADDR:
1207 neigh_changeaddr(&arp_tbl, dev);
1208 rt_cache_flush(dev_net(dev));
1209 break;
1210 case NETDEV_CHANGE:
1211 change_info = ptr;
1212 if (change_info->flags_changed & IFF_NOARP)
1213 neigh_changeaddr(&arp_tbl, dev);
1214 break;
1215 default:
1216 break;
1217 }
1218
1219 return NOTIFY_DONE;
1220}
1221
1222static struct notifier_block arp_netdev_notifier = {
1223 .notifier_call = arp_netdev_event,
1224};
1225
1226/* Note, that it is not on notifier chain.
1227 It is necessary, that this routine was called after route cache will be
1228 flushed.
1229 */
1230void arp_ifdown(struct net_device *dev)
1231{
1232 neigh_ifdown(&arp_tbl, dev);
1233}
1234
1235
1236/*
1237 * Called once on startup.
1238 */
1239
1240static struct packet_type arp_packet_type __read_mostly = {
1241 .type = cpu_to_be16(ETH_P_ARP),
1242 .func = arp_rcv,
1243};
1244
1245static int arp_proc_init(void);
1246
1247void __init arp_init(void)
1248{
1249 neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl);
1250
1251 dev_add_pack(&arp_packet_type);
1252 arp_proc_init();
1253#ifdef CONFIG_SYSCTL
1254 neigh_sysctl_register(NULL, &arp_tbl.parms, NULL);
1255#endif
1256 register_netdevice_notifier(&arp_netdev_notifier);
1257}
1258
1259#ifdef CONFIG_PROC_FS
1260#if IS_ENABLED(CONFIG_AX25)
1261
1262/* ------------------------------------------------------------------------ */
1263/*
1264 * ax25 -> ASCII conversion
1265 */
1266static char *ax2asc2(ax25_address *a, char *buf)
1267{
1268 char c, *s;
1269 int n;
1270
1271 for (n = 0, s = buf; n < 6; n++) {
1272 c = (a->ax25_call[n] >> 1) & 0x7F;
1273
1274 if (c != ' ')
1275 *s++ = c;
1276 }
1277
1278 *s++ = '-';
1279 n = (a->ax25_call[6] >> 1) & 0x0F;
1280 if (n > 9) {
1281 *s++ = '1';
1282 n -= 10;
1283 }
1284
1285 *s++ = n + '0';
1286 *s++ = '\0';
1287
1288 if (*buf == '\0' || *buf == '-')
1289 return "*";
1290
1291 return buf;
1292}
1293#endif /* CONFIG_AX25 */
1294
1295#define HBUFFERLEN 30
1296
1297static void arp_format_neigh_entry(struct seq_file *seq,
1298 struct neighbour *n)
1299{
1300 char hbuffer[HBUFFERLEN];
1301 int k, j;
1302 char tbuf[16];
1303 struct net_device *dev = n->dev;
1304 int hatype = dev->type;
1305
1306 read_lock(&n->lock);
1307 /* Convert hardware address to XX:XX:XX:XX ... form. */
1308#if IS_ENABLED(CONFIG_AX25)
1309 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1310 ax2asc2((ax25_address *)n->ha, hbuffer);
1311 else {
1312#endif
1313 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1314 hbuffer[k++] = hex_asc_hi(n->ha[j]);
1315 hbuffer[k++] = hex_asc_lo(n->ha[j]);
1316 hbuffer[k++] = ':';
1317 }
1318 if (k != 0)
1319 --k;
1320 hbuffer[k] = 0;
1321#if IS_ENABLED(CONFIG_AX25)
1322 }
1323#endif
1324 sprintf(tbuf, "%pI4", n->primary_key);
1325 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1326 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1327 read_unlock(&n->lock);
1328}
1329
1330static void arp_format_pneigh_entry(struct seq_file *seq,
1331 struct pneigh_entry *n)
1332{
1333 struct net_device *dev = n->dev;
1334 int hatype = dev ? dev->type : 0;
1335 char tbuf[16];
1336
1337 sprintf(tbuf, "%pI4", n->key);
1338 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1339 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1340 dev ? dev->name : "*");
1341}
1342
1343static int arp_seq_show(struct seq_file *seq, void *v)
1344{
1345 if (v == SEQ_START_TOKEN) {
1346 seq_puts(seq, "IP address HW type Flags "
1347 "HW address Mask Device\n");
1348 } else {
1349 struct neigh_seq_state *state = seq->private;
1350
1351 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1352 arp_format_pneigh_entry(seq, v);
1353 else
1354 arp_format_neigh_entry(seq, v);
1355 }
1356
1357 return 0;
1358}
1359
1360static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1361{
1362 /* Don't want to confuse "arp -a" w/ magic entries,
1363 * so we tell the generic iterator to skip NUD_NOARP.
1364 */
1365 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1366}
1367
1368/* ------------------------------------------------------------------------ */
1369
1370static const struct seq_operations arp_seq_ops = {
1371 .start = arp_seq_start,
1372 .next = neigh_seq_next,
1373 .stop = neigh_seq_stop,
1374 .show = arp_seq_show,
1375};
1376
1377static int arp_seq_open(struct inode *inode, struct file *file)
1378{
1379 return seq_open_net(inode, file, &arp_seq_ops,
1380 sizeof(struct neigh_seq_state));
1381}
1382
1383static const struct file_operations arp_seq_fops = {
1384 .owner = THIS_MODULE,
1385 .open = arp_seq_open,
1386 .read = seq_read,
1387 .llseek = seq_lseek,
1388 .release = seq_release_net,
1389};
1390
1391
1392static int __net_init arp_net_init(struct net *net)
1393{
1394 if (!proc_create("arp", S_IRUGO, net->proc_net, &arp_seq_fops))
1395 return -ENOMEM;
1396 return 0;
1397}
1398
1399static void __net_exit arp_net_exit(struct net *net)
1400{
1401 remove_proc_entry("arp", net->proc_net);
1402}
1403
1404static struct pernet_operations arp_net_ops = {
1405 .init = arp_net_init,
1406 .exit = arp_net_exit,
1407};
1408
1409static int __init arp_proc_init(void)
1410{
1411 return register_pernet_subsys(&arp_net_ops);
1412}
1413
1414#else /* CONFIG_PROC_FS */
1415
1416static int __init arp_proc_init(void)
1417{
1418 return 0;
1419}
1420
1421#endif /* CONFIG_PROC_FS */
1/* linux/net/ipv4/arp.c
2 *
3 * Copyright (C) 1994 by Florian La Roche
4 *
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
8 * address).
9 *
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.
14 *
15 * Fixes:
16 * Alan Cox : Removed the Ethernet assumptions in
17 * Florian's code
18 * Alan Cox : Fixed some small errors in the ARP
19 * logic
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
41 * during arp_rcv.
42 * Russ Nelson : Tidied up a few bits.
43 * Alexey Kuznetsov: Major changes to caching and behaviour,
44 * eg intelligent arp probing and
45 * generation
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
61 * one in...
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.
74 */
75
76#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
77
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>
86#include <linux/in.h>
87#include <linux/mm.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>
102#ifdef CONFIG_SYSCTL
103#include <linux/sysctl.h>
104#endif
105
106#include <net/net_namespace.h>
107#include <net/ip.h>
108#include <net/icmp.h>
109#include <net/route.h>
110#include <net/protocol.h>
111#include <net/tcp.h>
112#include <net/sock.h>
113#include <net/arp.h>
114#include <net/ax25.h>
115#include <net/netrom.h>
116
117#include <linux/uaccess.h>
118
119#include <linux/netfilter_arp.h>
120
121/*
122 * Interface to generic neighbour cache.
123 */
124static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd);
125static int arp_constructor(struct neighbour *neigh);
126static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
127static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
128static void parp_redo(struct sk_buff *skb);
129
130static const struct neigh_ops arp_generic_ops = {
131 .family = AF_INET,
132 .solicit = arp_solicit,
133 .error_report = arp_error_report,
134 .output = neigh_resolve_output,
135 .connected_output = neigh_connected_output,
136};
137
138static const struct neigh_ops arp_hh_ops = {
139 .family = AF_INET,
140 .solicit = arp_solicit,
141 .error_report = arp_error_report,
142 .output = neigh_resolve_output,
143 .connected_output = neigh_resolve_output,
144};
145
146static const struct neigh_ops arp_direct_ops = {
147 .family = AF_INET,
148 .output = neigh_direct_output,
149 .connected_output = neigh_direct_output,
150};
151
152static const struct neigh_ops arp_broken_ops = {
153 .family = AF_INET,
154 .solicit = arp_solicit,
155 .error_report = arp_error_report,
156 .output = neigh_compat_output,
157 .connected_output = neigh_compat_output,
158};
159
160struct neigh_table arp_tbl = {
161 .family = AF_INET,
162 .key_len = 4,
163 .hash = arp_hash,
164 .constructor = arp_constructor,
165 .proxy_redo = parp_redo,
166 .id = "arp_cache",
167 .parms = {
168 .tbl = &arp_tbl,
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,
175 .ucast_probes = 3,
176 .mcast_probes = 3,
177 .anycast_delay = 1 * HZ,
178 .proxy_delay = (8 * HZ) / 10,
179 .proxy_qlen = 64,
180 .locktime = 1 * HZ,
181 },
182 .gc_interval = 30 * HZ,
183 .gc_thresh1 = 128,
184 .gc_thresh2 = 512,
185 .gc_thresh3 = 1024,
186};
187EXPORT_SYMBOL(arp_tbl);
188
189int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir)
190{
191 switch (dev->type) {
192 case ARPHRD_ETHER:
193 case ARPHRD_FDDI:
194 case ARPHRD_IEEE802:
195 ip_eth_mc_map(addr, haddr);
196 return 0;
197 case ARPHRD_INFINIBAND:
198 ip_ib_mc_map(addr, dev->broadcast, haddr);
199 return 0;
200 case ARPHRD_IPGRE:
201 ip_ipgre_mc_map(addr, dev->broadcast, haddr);
202 return 0;
203 default:
204 if (dir) {
205 memcpy(haddr, dev->broadcast, dev->addr_len);
206 return 0;
207 }
208 }
209 return -EINVAL;
210}
211
212
213static u32 arp_hash(const void *pkey,
214 const struct net_device *dev,
215 __u32 *hash_rnd)
216{
217 return arp_hashfn(*(u32 *)pkey, dev, *hash_rnd);
218}
219
220static int arp_constructor(struct neighbour *neigh)
221{
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;
226
227 rcu_read_lock();
228 in_dev = __in_dev_get_rcu(dev);
229 if (in_dev == NULL) {
230 rcu_read_unlock();
231 return -EINVAL;
232 }
233
234 neigh->type = inet_addr_type(dev_net(dev), addr);
235
236 parms = in_dev->arp_parms;
237 __neigh_parms_put(neigh->parms);
238 neigh->parms = neigh_parms_clone(parms);
239 rcu_read_unlock();
240
241 if (!dev->header_ops) {
242 neigh->nud_state = NUD_NOARP;
243 neigh->ops = &arp_direct_ops;
244 neigh->output = neigh_direct_output;
245 } else {
246 /* Good devices (checked by reading texts, but only Ethernet is
247 tested)
248
249 ARPHRD_ETHER: (ethernet, apfddi)
250 ARPHRD_FDDI: (fddi)
251 ARPHRD_IEEE802: (tr)
252 ARPHRD_METRICOM: (strip)
253 ARPHRD_ARCNET:
254 etc. etc. etc.
255
256 ARPHRD_IPDDP will also work, if author repairs it.
257 I did not it, because this driver does not work even
258 in old paradigm.
259 */
260
261#if 1
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.
266
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.
272 */
273 switch (dev->type) {
274 default:
275 break;
276 case ARPHRD_ROSE:
277#if IS_ENABLED(CONFIG_AX25)
278 case ARPHRD_AX25:
279#if IS_ENABLED(CONFIG_NETROM)
280 case ARPHRD_NETROM:
281#endif
282 neigh->ops = &arp_broken_ops;
283 neigh->output = neigh->ops->output;
284 return 0;
285#else
286 break;
287#endif
288 }
289#endif
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);
300 }
301
302 if (dev->header_ops->cache)
303 neigh->ops = &arp_hh_ops;
304 else
305 neigh->ops = &arp_generic_ops;
306
307 if (neigh->nud_state & NUD_VALID)
308 neigh->output = neigh->ops->connected_output;
309 else
310 neigh->output = neigh->ops->output;
311 }
312 return 0;
313}
314
315static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
316{
317 dst_link_failure(skb);
318 kfree_skb(skb);
319}
320
321static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
322{
323 __be32 saddr = 0;
324 u8 *dst_ha = NULL;
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;
329
330 rcu_read_lock();
331 in_dev = __in_dev_get_rcu(dev);
332 if (!in_dev) {
333 rcu_read_unlock();
334 return;
335 }
336 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
337 default:
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;
342 break;
343 case 1: /* Restrict announcements of saddr in same subnet */
344 if (!skb)
345 break;
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))
350 break;
351 }
352 saddr = 0;
353 break;
354 case 2: /* Avoid secondary IPs, get a primary/preferred one */
355 break;
356 }
357 rcu_read_unlock();
358
359 if (!saddr)
360 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
361
362 probes -= neigh->parms->ucast_probes;
363 if (probes < 0) {
364 if (!(neigh->nud_state & NUD_VALID))
365 pr_debug("trying to ucast probe in NUD_INVALID\n");
366 dst_ha = neigh->ha;
367 read_lock_bh(&neigh->lock);
368 } else {
369 probes -= neigh->parms->app_probes;
370 if (probes < 0) {
371#ifdef CONFIG_ARPD
372 neigh_app_ns(neigh);
373#endif
374 return;
375 }
376 }
377
378 arp_send(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
379 dst_ha, dev->dev_addr, NULL);
380 if (dst_ha)
381 read_unlock_bh(&neigh->lock);
382}
383
384static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip)
385{
386 int scope;
387
388 switch (IN_DEV_ARP_IGNORE(in_dev)) {
389 case 0: /* Reply, the tip is already validated */
390 return 0;
391 case 1: /* Reply only if tip is configured on the incoming interface */
392 sip = 0;
393 scope = RT_SCOPE_HOST;
394 break;
395 case 2: /*
396 * Reply only if tip is configured on the incoming interface
397 * and is in same subnet as sip
398 */
399 scope = RT_SCOPE_HOST;
400 break;
401 case 3: /* Do not reply for scope host addresses */
402 sip = 0;
403 scope = RT_SCOPE_LINK;
404 break;
405 case 4: /* Reserved */
406 case 5:
407 case 6:
408 case 7:
409 return 0;
410 case 8: /* Do not reply */
411 return 1;
412 default:
413 return 0;
414 }
415 return !inet_confirm_addr(in_dev, sip, tip, scope);
416}
417
418static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
419{
420 struct rtable *rt;
421 int flag = 0;
422 /*unsigned long now; */
423 struct net *net = dev_net(dev);
424
425 rt = ip_route_output(net, sip, tip, 0, 0);
426 if (IS_ERR(rt))
427 return 1;
428 if (rt->dst.dev != dev) {
429 NET_INC_STATS_BH(net, LINUX_MIB_ARPFILTER);
430 flag = 1;
431 }
432 ip_rt_put(rt);
433 return flag;
434}
435
436/* OBSOLETE FUNCTIONS */
437
438/*
439 * Find an arp mapping in the cache. If not found, post a request.
440 *
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
445 */
446
447static int arp_set_predefined(int addr_hint, unsigned char *haddr,
448 __be32 paddr, struct net_device *dev)
449{
450 switch (addr_hint) {
451 case RTN_LOCAL:
452 pr_debug("arp called for own IP address\n");
453 memcpy(haddr, dev->dev_addr, dev->addr_len);
454 return 1;
455 case RTN_MULTICAST:
456 arp_mc_map(paddr, haddr, dev, 1);
457 return 1;
458 case RTN_BROADCAST:
459 memcpy(haddr, dev->broadcast, dev->addr_len);
460 return 1;
461 }
462 return 0;
463}
464
465
466int arp_find(unsigned char *haddr, struct sk_buff *skb)
467{
468 struct net_device *dev = skb->dev;
469 __be32 paddr;
470 struct neighbour *n;
471
472 if (!skb_dst(skb)) {
473 pr_debug("arp_find is called with dst==NULL\n");
474 kfree_skb(skb);
475 return 1;
476 }
477
478 paddr = skb_rtable(skb)->rt_gateway;
479
480 if (arp_set_predefined(inet_addr_type(dev_net(dev), paddr), haddr,
481 paddr, dev))
482 return 0;
483
484 n = __neigh_lookup(&arp_tbl, &paddr, dev, 1);
485
486 if (n) {
487 n->used = jiffies;
488 if (n->nud_state & NUD_VALID || neigh_event_send(n, skb) == 0) {
489 neigh_ha_snapshot(haddr, n, dev);
490 neigh_release(n);
491 return 0;
492 }
493 neigh_release(n);
494 } else
495 kfree_skb(skb);
496 return 1;
497}
498EXPORT_SYMBOL(arp_find);
499
500/* END OF OBSOLETE FUNCTIONS */
501
502/*
503 * Check if we can use proxy ARP for this path
504 */
505static inline int arp_fwd_proxy(struct in_device *in_dev,
506 struct net_device *dev, struct rtable *rt)
507{
508 struct in_device *out_dev;
509 int imi, omi = -1;
510
511 if (rt->dst.dev == dev)
512 return 0;
513
514 if (!IN_DEV_PROXY_ARP(in_dev))
515 return 0;
516 imi = IN_DEV_MEDIUM_ID(in_dev);
517 if (imi == 0)
518 return 1;
519 if (imi == -1)
520 return 0;
521
522 /* place to check for proxy_arp for routes */
523
524 out_dev = __in_dev_get_rcu(rt->dst.dev);
525 if (out_dev)
526 omi = IN_DEV_MEDIUM_ID(out_dev);
527
528 return omi != imi && omi != -1;
529}
530
531/*
532 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
533 *
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.
540 *
541 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
542 *
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).
548 *
549 */
550static inline int arp_fwd_pvlan(struct in_device *in_dev,
551 struct net_device *dev, struct rtable *rt,
552 __be32 sip, __be32 tip)
553{
554 /* Private VLAN is only concerned about the same ethernet segment */
555 if (rt->dst.dev != dev)
556 return 0;
557
558 /* Don't reply on self probes (often done by windowz boxes)*/
559 if (sip == tip)
560 return 0;
561
562 if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
563 return 1;
564 else
565 return 0;
566}
567
568/*
569 * Interface to link layer: send routine and receive handler.
570 */
571
572/*
573 * Create an arp packet. If (dest_hw == NULL), we create a broadcast
574 * message.
575 */
576struct 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)
581{
582 struct sk_buff *skb;
583 struct arphdr *arp;
584 unsigned char *arp_ptr;
585 int hlen = LL_RESERVED_SPACE(dev);
586 int tlen = dev->needed_tailroom;
587
588 /*
589 * Allocate a buffer
590 */
591
592 skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
593 if (skb == NULL)
594 return NULL;
595
596 skb_reserve(skb, hlen);
597 skb_reset_network_header(skb);
598 arp = (struct arphdr *) skb_put(skb, arp_hdr_len(dev));
599 skb->dev = dev;
600 skb->protocol = htons(ETH_P_ARP);
601 if (src_hw == NULL)
602 src_hw = dev->dev_addr;
603 if (dest_hw == NULL)
604 dest_hw = dev->broadcast;
605
606 /*
607 * Fill the device header for the ARP frame
608 */
609 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
610 goto out;
611
612 /*
613 * Fill out the arp protocol part.
614 *
615 * The arp hardware type should match the device type, except for FDDI,
616 * which (according to RFC 1390) should always equal 1 (Ethernet).
617 */
618 /*
619 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
620 * DIX code for the protocol. Make these device structure fields.
621 */
622 switch (dev->type) {
623 default:
624 arp->ar_hrd = htons(dev->type);
625 arp->ar_pro = htons(ETH_P_IP);
626 break;
627
628#if IS_ENABLED(CONFIG_AX25)
629 case ARPHRD_AX25:
630 arp->ar_hrd = htons(ARPHRD_AX25);
631 arp->ar_pro = htons(AX25_P_IP);
632 break;
633
634#if IS_ENABLED(CONFIG_NETROM)
635 case ARPHRD_NETROM:
636 arp->ar_hrd = htons(ARPHRD_NETROM);
637 arp->ar_pro = htons(AX25_P_IP);
638 break;
639#endif
640#endif
641
642#if IS_ENABLED(CONFIG_FDDI)
643 case ARPHRD_FDDI:
644 arp->ar_hrd = htons(ARPHRD_ETHER);
645 arp->ar_pro = htons(ETH_P_IP);
646 break;
647#endif
648 }
649
650 arp->ar_hln = dev->addr_len;
651 arp->ar_pln = 4;
652 arp->ar_op = htons(type);
653
654 arp_ptr = (unsigned char *)(arp + 1);
655
656 memcpy(arp_ptr, src_hw, dev->addr_len);
657 arp_ptr += dev->addr_len;
658 memcpy(arp_ptr, &src_ip, 4);
659 arp_ptr += 4;
660 if (target_hw != NULL)
661 memcpy(arp_ptr, target_hw, dev->addr_len);
662 else
663 memset(arp_ptr, 0, dev->addr_len);
664 arp_ptr += dev->addr_len;
665 memcpy(arp_ptr, &dest_ip, 4);
666
667 return skb;
668
669out:
670 kfree_skb(skb);
671 return NULL;
672}
673EXPORT_SYMBOL(arp_create);
674
675/*
676 * Send an arp packet.
677 */
678void arp_xmit(struct sk_buff *skb)
679{
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);
682}
683EXPORT_SYMBOL(arp_xmit);
684
685/*
686 * Create and send an arp packet.
687 */
688void 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)
692{
693 struct sk_buff *skb;
694
695 /*
696 * No arp on this interface.
697 */
698
699 if (dev->flags&IFF_NOARP)
700 return;
701
702 skb = arp_create(type, ptype, dest_ip, dev, src_ip,
703 dest_hw, src_hw, target_hw);
704 if (skb == NULL)
705 return;
706
707 arp_xmit(skb);
708}
709EXPORT_SYMBOL(arp_send);
710
711/*
712 * Process an arp request.
713 */
714
715static int arp_process(struct sk_buff *skb)
716{
717 struct net_device *dev = skb->dev;
718 struct in_device *in_dev = __in_dev_get_rcu(dev);
719 struct arphdr *arp;
720 unsigned char *arp_ptr;
721 struct rtable *rt;
722 unsigned char *sha;
723 __be32 sip, tip;
724 u16 dev_type = dev->type;
725 int addr_type;
726 struct neighbour *n;
727 struct net *net = dev_net(dev);
728
729 /* arp_rcv below verifies the ARP header and verifies the device
730 * is ARP'able.
731 */
732
733 if (in_dev == NULL)
734 goto out;
735
736 arp = arp_hdr(skb);
737
738 switch (dev_type) {
739 default:
740 if (arp->ar_pro != htons(ETH_P_IP) ||
741 htons(dev_type) != arp->ar_hrd)
742 goto out;
743 break;
744 case ARPHRD_ETHER:
745 case ARPHRD_FDDI:
746 case ARPHRD_IEEE802:
747 /*
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)
754 * or 6 (IEEE 802.2)
755 */
756 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
757 arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
758 arp->ar_pro != htons(ETH_P_IP))
759 goto out;
760 break;
761 case ARPHRD_AX25:
762 if (arp->ar_pro != htons(AX25_P_IP) ||
763 arp->ar_hrd != htons(ARPHRD_AX25))
764 goto out;
765 break;
766 case ARPHRD_NETROM:
767 if (arp->ar_pro != htons(AX25_P_IP) ||
768 arp->ar_hrd != htons(ARPHRD_NETROM))
769 goto out;
770 break;
771 }
772
773 /* Understand only these message types */
774
775 if (arp->ar_op != htons(ARPOP_REPLY) &&
776 arp->ar_op != htons(ARPOP_REQUEST))
777 goto out;
778
779/*
780 * Extract fields
781 */
782 arp_ptr = (unsigned char *)(arp + 1);
783 sha = arp_ptr;
784 arp_ptr += dev->addr_len;
785 memcpy(&sip, arp_ptr, 4);
786 arp_ptr += 4;
787 arp_ptr += dev->addr_len;
788 memcpy(&tip, arp_ptr, 4);
789/*
790 * Check for bad requests for 127.x.x.x and requests for multicast
791 * addresses. If this is one such, delete it.
792 */
793 if (ipv4_is_loopback(tip) || ipv4_is_multicast(tip))
794 goto out;
795
796/*
797 * Special case: We must set Frame Relay source Q.922 address
798 */
799 if (dev_type == ARPHRD_DLCI)
800 sha = dev->broadcast;
801
802/*
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.)
811 *
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
816 * cache.
817 */
818
819 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
820 if (sip == 0) {
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,
825 dev->dev_addr, sha);
826 goto out;
827 }
828
829 if (arp->ar_op == htons(ARPOP_REQUEST) &&
830 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
831
832 rt = skb_rtable(skb);
833 addr_type = rt->rt_type;
834
835 if (addr_type == RTN_LOCAL) {
836 int dont_send;
837
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);
841 if (!dont_send) {
842 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
843 if (n) {
844 arp_send(ARPOP_REPLY, ETH_P_ARP, sip,
845 dev, tip, sha, dev->dev_addr,
846 sha);
847 neigh_release(n);
848 }
849 }
850 goto out;
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);
858 if (n)
859 neigh_release(n);
860
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,
866 sha);
867 } else {
868 pneigh_enqueue(&arp_tbl,
869 in_dev->arp_parms, skb);
870 return 0;
871 }
872 goto out;
873 }
874 }
875 }
876
877 /* Update our ARP tables */
878
879 n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
880
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)
885 */
886 if (n == NULL &&
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);
891 }
892
893 if (n) {
894 int state = NUD_REACHABLE;
895 int override;
896
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.
901 */
902 override = time_after(jiffies, n->updated + n->parms->locktime);
903
904 /* Broadcast replies and request packets
905 do not assert neighbour reachability.
906 */
907 if (arp->ar_op != htons(ARPOP_REPLY) ||
908 skb->pkt_type != PACKET_HOST)
909 state = NUD_STALE;
910 neigh_update(n, sha, state,
911 override ? NEIGH_UPDATE_F_OVERRIDE : 0);
912 neigh_release(n);
913 }
914
915out:
916 consume_skb(skb);
917 return 0;
918}
919
920static void parp_redo(struct sk_buff *skb)
921{
922 arp_process(skb);
923}
924
925
926/*
927 * Receive an arp request from the device layer.
928 */
929
930static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
931 struct packet_type *pt, struct net_device *orig_dev)
932{
933 struct arphdr *arp;
934
935 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
936 if (!pskb_may_pull(skb, arp_hdr_len(dev)))
937 goto freeskb;
938
939 arp = arp_hdr(skb);
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 ||
944 arp->ar_pln != 4)
945 goto freeskb;
946
947 skb = skb_share_check(skb, GFP_ATOMIC);
948 if (skb == NULL)
949 goto out_of_mem;
950
951 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
952
953 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, skb, dev, NULL, arp_process);
954
955freeskb:
956 kfree_skb(skb);
957out_of_mem:
958 return 0;
959}
960
961/*
962 * User level interface (ioctl)
963 */
964
965/*
966 * Set (create) an ARP cache entry.
967 */
968
969static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
970{
971 if (dev == NULL) {
972 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
973 return 0;
974 }
975 if (__in_dev_get_rtnl(dev)) {
976 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
977 return 0;
978 }
979 return -ENXIO;
980}
981
982static int arp_req_set_public(struct net *net, struct arpreq *r,
983 struct net_device *dev)
984{
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;
987
988 if (mask && mask != htonl(0xFFFFFFFF))
989 return -EINVAL;
990 if (!dev && (r->arp_flags & ATF_COM)) {
991 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family,
992 r->arp_ha.sa_data);
993 if (!dev)
994 return -ENODEV;
995 }
996 if (mask) {
997 if (pneigh_lookup(&arp_tbl, net, &ip, dev, 1) == NULL)
998 return -ENOBUFS;
999 return 0;
1000 }
1001
1002 return arp_req_set_proxy(net, dev, 1);
1003}
1004
1005static int arp_req_set(struct net *net, struct arpreq *r,
1006 struct net_device *dev)
1007{
1008 __be32 ip;
1009 struct neighbour *neigh;
1010 int err;
1011
1012 if (r->arp_flags & ATF_PUBL)
1013 return arp_req_set_public(net, r, dev);
1014
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;
1018 if (dev == NULL) {
1019 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1020
1021 if (IS_ERR(rt))
1022 return PTR_ERR(rt);
1023 dev = rt->dst.dev;
1024 ip_rt_put(rt);
1025 if (!dev)
1026 return -EINVAL;
1027 }
1028 switch (dev->type) {
1029#if IS_ENABLED(CONFIG_FDDI)
1030 case ARPHRD_FDDI:
1031 /*
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).
1036 */
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)
1040 return -EINVAL;
1041 break;
1042#endif
1043 default:
1044 if (r->arp_ha.sa_family != dev->type)
1045 return -EINVAL;
1046 break;
1047 }
1048
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);
1060 }
1061 return err;
1062}
1063
1064static unsigned int arp_state_to_flags(struct neighbour *neigh)
1065{
1066 if (neigh->nud_state&NUD_PERMANENT)
1067 return ATF_PERM | ATF_COM;
1068 else if (neigh->nud_state&NUD_VALID)
1069 return ATF_COM;
1070 else
1071 return 0;
1072}
1073
1074/*
1075 * Get an ARP cache entry.
1076 */
1077
1078static int arp_req_get(struct arpreq *r, struct net_device *dev)
1079{
1080 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1081 struct neighbour *neigh;
1082 int err = -ENXIO;
1083
1084 neigh = neigh_lookup(&arp_tbl, &ip, dev);
1085 if (neigh) {
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);
1093 err = 0;
1094 }
1095 return err;
1096}
1097
1098int arp_invalidate(struct net_device *dev, __be32 ip)
1099{
1100 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
1101 int err = -ENXIO;
1102
1103 if (neigh) {
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);
1109 }
1110
1111 return err;
1112}
1113EXPORT_SYMBOL(arp_invalidate);
1114
1115static int arp_req_delete_public(struct net *net, struct arpreq *r,
1116 struct net_device *dev)
1117{
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;
1120
1121 if (mask == htonl(0xFFFFFFFF))
1122 return pneigh_delete(&arp_tbl, net, &ip, dev);
1123
1124 if (mask)
1125 return -EINVAL;
1126
1127 return arp_req_set_proxy(net, dev, 0);
1128}
1129
1130static int arp_req_delete(struct net *net, struct arpreq *r,
1131 struct net_device *dev)
1132{
1133 __be32 ip;
1134
1135 if (r->arp_flags & ATF_PUBL)
1136 return arp_req_delete_public(net, r, dev);
1137
1138 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1139 if (dev == NULL) {
1140 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1141 if (IS_ERR(rt))
1142 return PTR_ERR(rt);
1143 dev = rt->dst.dev;
1144 ip_rt_put(rt);
1145 if (!dev)
1146 return -EINVAL;
1147 }
1148 return arp_invalidate(dev, ip);
1149}
1150
1151/*
1152 * Handle an ARP layer I/O control request.
1153 */
1154
1155int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1156{
1157 int err;
1158 struct arpreq r;
1159 struct net_device *dev = NULL;
1160
1161 switch (cmd) {
1162 case SIOCDARP:
1163 case SIOCSARP:
1164 if (!capable(CAP_NET_ADMIN))
1165 return -EPERM;
1166 case SIOCGARP:
1167 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1168 if (err)
1169 return -EFAULT;
1170 break;
1171 default:
1172 return -EINVAL;
1173 }
1174
1175 if (r.arp_pa.sa_family != AF_INET)
1176 return -EPFNOSUPPORT;
1177
1178 if (!(r.arp_flags & ATF_PUBL) &&
1179 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1180 return -EINVAL;
1181 if (!(r.arp_flags & ATF_NETMASK))
1182 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1183 htonl(0xFFFFFFFFUL);
1184 rtnl_lock();
1185 if (r.arp_dev[0]) {
1186 err = -ENODEV;
1187 dev = __dev_get_by_name(net, r.arp_dev);
1188 if (dev == NULL)
1189 goto out;
1190
1191 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1192 if (!r.arp_ha.sa_family)
1193 r.arp_ha.sa_family = dev->type;
1194 err = -EINVAL;
1195 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1196 goto out;
1197 } else if (cmd == SIOCGARP) {
1198 err = -ENODEV;
1199 goto out;
1200 }
1201
1202 switch (cmd) {
1203 case SIOCDARP:
1204 err = arp_req_delete(net, &r, dev);
1205 break;
1206 case SIOCSARP:
1207 err = arp_req_set(net, &r, dev);
1208 break;
1209 case SIOCGARP:
1210 err = arp_req_get(&r, dev);
1211 break;
1212 }
1213out:
1214 rtnl_unlock();
1215 if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
1216 err = -EFAULT;
1217 return err;
1218}
1219
1220static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1221 void *ptr)
1222{
1223 struct net_device *dev = ptr;
1224
1225 switch (event) {
1226 case NETDEV_CHANGEADDR:
1227 neigh_changeaddr(&arp_tbl, dev);
1228 rt_cache_flush(dev_net(dev), 0);
1229 break;
1230 default:
1231 break;
1232 }
1233
1234 return NOTIFY_DONE;
1235}
1236
1237static struct notifier_block arp_netdev_notifier = {
1238 .notifier_call = arp_netdev_event,
1239};
1240
1241/* Note, that it is not on notifier chain.
1242 It is necessary, that this routine was called after route cache will be
1243 flushed.
1244 */
1245void arp_ifdown(struct net_device *dev)
1246{
1247 neigh_ifdown(&arp_tbl, dev);
1248}
1249
1250
1251/*
1252 * Called once on startup.
1253 */
1254
1255static struct packet_type arp_packet_type __read_mostly = {
1256 .type = cpu_to_be16(ETH_P_ARP),
1257 .func = arp_rcv,
1258};
1259
1260static int arp_proc_init(void);
1261
1262void __init arp_init(void)
1263{
1264 neigh_table_init(&arp_tbl);
1265
1266 dev_add_pack(&arp_packet_type);
1267 arp_proc_init();
1268#ifdef CONFIG_SYSCTL
1269 neigh_sysctl_register(NULL, &arp_tbl.parms, "ipv4", NULL);
1270#endif
1271 register_netdevice_notifier(&arp_netdev_notifier);
1272}
1273
1274#ifdef CONFIG_PROC_FS
1275#if IS_ENABLED(CONFIG_AX25)
1276
1277/* ------------------------------------------------------------------------ */
1278/*
1279 * ax25 -> ASCII conversion
1280 */
1281static char *ax2asc2(ax25_address *a, char *buf)
1282{
1283 char c, *s;
1284 int n;
1285
1286 for (n = 0, s = buf; n < 6; n++) {
1287 c = (a->ax25_call[n] >> 1) & 0x7F;
1288
1289 if (c != ' ')
1290 *s++ = c;
1291 }
1292
1293 *s++ = '-';
1294 n = (a->ax25_call[6] >> 1) & 0x0F;
1295 if (n > 9) {
1296 *s++ = '1';
1297 n -= 10;
1298 }
1299
1300 *s++ = n + '0';
1301 *s++ = '\0';
1302
1303 if (*buf == '\0' || *buf == '-')
1304 return "*";
1305
1306 return buf;
1307}
1308#endif /* CONFIG_AX25 */
1309
1310#define HBUFFERLEN 30
1311
1312static void arp_format_neigh_entry(struct seq_file *seq,
1313 struct neighbour *n)
1314{
1315 char hbuffer[HBUFFERLEN];
1316 int k, j;
1317 char tbuf[16];
1318 struct net_device *dev = n->dev;
1319 int hatype = dev->type;
1320
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);
1326 else {
1327#endif
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]);
1331 hbuffer[k++] = ':';
1332 }
1333 if (k != 0)
1334 --k;
1335 hbuffer[k] = 0;
1336#if IS_ENABLED(CONFIG_AX25)
1337 }
1338#endif
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);
1343}
1344
1345static void arp_format_pneigh_entry(struct seq_file *seq,
1346 struct pneigh_entry *n)
1347{
1348 struct net_device *dev = n->dev;
1349 int hatype = dev ? dev->type : 0;
1350 char tbuf[16];
1351
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 : "*");
1356}
1357
1358static int arp_seq_show(struct seq_file *seq, void *v)
1359{
1360 if (v == SEQ_START_TOKEN) {
1361 seq_puts(seq, "IP address HW type Flags "
1362 "HW address Mask Device\n");
1363 } else {
1364 struct neigh_seq_state *state = seq->private;
1365
1366 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1367 arp_format_pneigh_entry(seq, v);
1368 else
1369 arp_format_neigh_entry(seq, v);
1370 }
1371
1372 return 0;
1373}
1374
1375static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1376{
1377 /* Don't want to confuse "arp -a" w/ magic entries,
1378 * so we tell the generic iterator to skip NUD_NOARP.
1379 */
1380 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1381}
1382
1383/* ------------------------------------------------------------------------ */
1384
1385static 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,
1390};
1391
1392static int arp_seq_open(struct inode *inode, struct file *file)
1393{
1394 return seq_open_net(inode, file, &arp_seq_ops,
1395 sizeof(struct neigh_seq_state));
1396}
1397
1398static const struct file_operations arp_seq_fops = {
1399 .owner = THIS_MODULE,
1400 .open = arp_seq_open,
1401 .read = seq_read,
1402 .llseek = seq_lseek,
1403 .release = seq_release_net,
1404};
1405
1406
1407static int __net_init arp_net_init(struct net *net)
1408{
1409 if (!proc_net_fops_create(net, "arp", S_IRUGO, &arp_seq_fops))
1410 return -ENOMEM;
1411 return 0;
1412}
1413
1414static void __net_exit arp_net_exit(struct net *net)
1415{
1416 proc_net_remove(net, "arp");
1417}
1418
1419static struct pernet_operations arp_net_ops = {
1420 .init = arp_net_init,
1421 .exit = arp_net_exit,
1422};
1423
1424static int __init arp_proc_init(void)
1425{
1426 return register_pernet_subsys(&arp_net_ops);
1427}
1428
1429#else /* CONFIG_PROC_FS */
1430
1431static int __init arp_proc_init(void)
1432{
1433 return 0;
1434}
1435
1436#endif /* CONFIG_PROC_FS */