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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] = SK_WMEM_MAX,
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;
227 struct net_device *dev = neigh->dev;
228 struct in_device *in_dev;
229 struct neigh_parms *parms;
230 u32 inaddr_any = INADDR_ANY;
231
232 if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT))
233 memcpy(neigh->primary_key, &inaddr_any, arp_tbl.key_len);
234
235 addr = *(__be32 *)neigh->primary_key;
236 rcu_read_lock();
237 in_dev = __in_dev_get_rcu(dev);
238 if (!in_dev) {
239 rcu_read_unlock();
240 return -EINVAL;
241 }
242
243 neigh->type = inet_addr_type_dev_table(dev_net(dev), dev, addr);
244
245 parms = in_dev->arp_parms;
246 __neigh_parms_put(neigh->parms);
247 neigh->parms = neigh_parms_clone(parms);
248 rcu_read_unlock();
249
250 if (!dev->header_ops) {
251 neigh->nud_state = NUD_NOARP;
252 neigh->ops = &arp_direct_ops;
253 neigh->output = neigh_direct_output;
254 } else {
255 /* Good devices (checked by reading texts, but only Ethernet is
256 tested)
257
258 ARPHRD_ETHER: (ethernet, apfddi)
259 ARPHRD_FDDI: (fddi)
260 ARPHRD_IEEE802: (tr)
261 ARPHRD_METRICOM: (strip)
262 ARPHRD_ARCNET:
263 etc. etc. etc.
264
265 ARPHRD_IPDDP will also work, if author repairs it.
266 I did not it, because this driver does not work even
267 in old paradigm.
268 */
269
270 if (neigh->type == RTN_MULTICAST) {
271 neigh->nud_state = NUD_NOARP;
272 arp_mc_map(addr, neigh->ha, dev, 1);
273 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) {
274 neigh->nud_state = NUD_NOARP;
275 memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
276 } else if (neigh->type == RTN_BROADCAST ||
277 (dev->flags & IFF_POINTOPOINT)) {
278 neigh->nud_state = NUD_NOARP;
279 memcpy(neigh->ha, dev->broadcast, dev->addr_len);
280 }
281
282 if (dev->header_ops->cache)
283 neigh->ops = &arp_hh_ops;
284 else
285 neigh->ops = &arp_generic_ops;
286
287 if (neigh->nud_state & NUD_VALID)
288 neigh->output = neigh->ops->connected_output;
289 else
290 neigh->output = neigh->ops->output;
291 }
292 return 0;
293}
294
295static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
296{
297 dst_link_failure(skb);
298 kfree_skb(skb);
299}
300
301/* Create and send an arp packet. */
302static void arp_send_dst(int type, int ptype, __be32 dest_ip,
303 struct net_device *dev, __be32 src_ip,
304 const unsigned char *dest_hw,
305 const unsigned char *src_hw,
306 const unsigned char *target_hw,
307 struct dst_entry *dst)
308{
309 struct sk_buff *skb;
310
311 /* arp on this interface. */
312 if (dev->flags & IFF_NOARP)
313 return;
314
315 skb = arp_create(type, ptype, dest_ip, dev, src_ip,
316 dest_hw, src_hw, target_hw);
317 if (!skb)
318 return;
319
320 skb_dst_set(skb, dst_clone(dst));
321 arp_xmit(skb);
322}
323
324void arp_send(int type, int ptype, __be32 dest_ip,
325 struct net_device *dev, __be32 src_ip,
326 const unsigned char *dest_hw, const unsigned char *src_hw,
327 const unsigned char *target_hw)
328{
329 arp_send_dst(type, ptype, dest_ip, dev, src_ip, dest_hw, src_hw,
330 target_hw, NULL);
331}
332EXPORT_SYMBOL(arp_send);
333
334static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
335{
336 __be32 saddr = 0;
337 u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL;
338 struct net_device *dev = neigh->dev;
339 __be32 target = *(__be32 *)neigh->primary_key;
340 int probes = atomic_read(&neigh->probes);
341 struct in_device *in_dev;
342 struct dst_entry *dst = NULL;
343
344 rcu_read_lock();
345 in_dev = __in_dev_get_rcu(dev);
346 if (!in_dev) {
347 rcu_read_unlock();
348 return;
349 }
350 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
351 default:
352 case 0: /* By default announce any local IP */
353 if (skb && inet_addr_type_dev_table(dev_net(dev), dev,
354 ip_hdr(skb)->saddr) == RTN_LOCAL)
355 saddr = ip_hdr(skb)->saddr;
356 break;
357 case 1: /* Restrict announcements of saddr in same subnet */
358 if (!skb)
359 break;
360 saddr = ip_hdr(skb)->saddr;
361 if (inet_addr_type_dev_table(dev_net(dev), dev,
362 saddr) == RTN_LOCAL) {
363 /* saddr should be known to target */
364 if (inet_addr_onlink(in_dev, target, saddr))
365 break;
366 }
367 saddr = 0;
368 break;
369 case 2: /* Avoid secondary IPs, get a primary/preferred one */
370 break;
371 }
372 rcu_read_unlock();
373
374 if (!saddr)
375 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
376
377 probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES);
378 if (probes < 0) {
379 if (!(neigh->nud_state & NUD_VALID))
380 pr_debug("trying to ucast probe in NUD_INVALID\n");
381 neigh_ha_snapshot(dst_ha, neigh, dev);
382 dst_hw = dst_ha;
383 } else {
384 probes -= NEIGH_VAR(neigh->parms, APP_PROBES);
385 if (probes < 0) {
386 neigh_app_ns(neigh);
387 return;
388 }
389 }
390
391 if (skb && !(dev->priv_flags & IFF_XMIT_DST_RELEASE))
392 dst = skb_dst(skb);
393 arp_send_dst(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
394 dst_hw, dev->dev_addr, NULL, dst);
395}
396
397static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip)
398{
399 struct net *net = dev_net(in_dev->dev);
400 int scope;
401
402 switch (IN_DEV_ARP_IGNORE(in_dev)) {
403 case 0: /* Reply, the tip is already validated */
404 return 0;
405 case 1: /* Reply only if tip is configured on the incoming interface */
406 sip = 0;
407 scope = RT_SCOPE_HOST;
408 break;
409 case 2: /*
410 * Reply only if tip is configured on the incoming interface
411 * and is in same subnet as sip
412 */
413 scope = RT_SCOPE_HOST;
414 break;
415 case 3: /* Do not reply for scope host addresses */
416 sip = 0;
417 scope = RT_SCOPE_LINK;
418 in_dev = NULL;
419 break;
420 case 4: /* Reserved */
421 case 5:
422 case 6:
423 case 7:
424 return 0;
425 case 8: /* Do not reply */
426 return 1;
427 default:
428 return 0;
429 }
430 return !inet_confirm_addr(net, in_dev, sip, tip, scope);
431}
432
433static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
434{
435 struct rtable *rt;
436 int flag = 0;
437 /*unsigned long now; */
438 struct net *net = dev_net(dev);
439
440 rt = ip_route_output(net, sip, tip, 0, l3mdev_master_ifindex_rcu(dev));
441 if (IS_ERR(rt))
442 return 1;
443 if (rt->dst.dev != dev) {
444 __NET_INC_STATS(net, LINUX_MIB_ARPFILTER);
445 flag = 1;
446 }
447 ip_rt_put(rt);
448 return flag;
449}
450
451/*
452 * Check if we can use proxy ARP for this path
453 */
454static inline int arp_fwd_proxy(struct in_device *in_dev,
455 struct net_device *dev, struct rtable *rt)
456{
457 struct in_device *out_dev;
458 int imi, omi = -1;
459
460 if (rt->dst.dev == dev)
461 return 0;
462
463 if (!IN_DEV_PROXY_ARP(in_dev))
464 return 0;
465 imi = IN_DEV_MEDIUM_ID(in_dev);
466 if (imi == 0)
467 return 1;
468 if (imi == -1)
469 return 0;
470
471 /* place to check for proxy_arp for routes */
472
473 out_dev = __in_dev_get_rcu(rt->dst.dev);
474 if (out_dev)
475 omi = IN_DEV_MEDIUM_ID(out_dev);
476
477 return omi != imi && omi != -1;
478}
479
480/*
481 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
482 *
483 * RFC3069 supports proxy arp replies back to the same interface. This
484 * is done to support (ethernet) switch features, like RFC 3069, where
485 * the individual ports are not allowed to communicate with each
486 * other, BUT they are allowed to talk to the upstream router. As
487 * described in RFC 3069, it is possible to allow these hosts to
488 * communicate through the upstream router, by proxy_arp'ing.
489 *
490 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
491 *
492 * This technology is known by different names:
493 * In RFC 3069 it is called VLAN Aggregation.
494 * Cisco and Allied Telesyn call it Private VLAN.
495 * Hewlett-Packard call it Source-Port filtering or port-isolation.
496 * Ericsson call it MAC-Forced Forwarding (RFC Draft).
497 *
498 */
499static inline int arp_fwd_pvlan(struct in_device *in_dev,
500 struct net_device *dev, struct rtable *rt,
501 __be32 sip, __be32 tip)
502{
503 /* Private VLAN is only concerned about the same ethernet segment */
504 if (rt->dst.dev != dev)
505 return 0;
506
507 /* Don't reply on self probes (often done by windowz boxes)*/
508 if (sip == tip)
509 return 0;
510
511 if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
512 return 1;
513 else
514 return 0;
515}
516
517/*
518 * Interface to link layer: send routine and receive handler.
519 */
520
521/*
522 * Create an arp packet. If dest_hw is not set, we create a broadcast
523 * message.
524 */
525struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
526 struct net_device *dev, __be32 src_ip,
527 const unsigned char *dest_hw,
528 const unsigned char *src_hw,
529 const unsigned char *target_hw)
530{
531 struct sk_buff *skb;
532 struct arphdr *arp;
533 unsigned char *arp_ptr;
534 int hlen = LL_RESERVED_SPACE(dev);
535 int tlen = dev->needed_tailroom;
536
537 /*
538 * Allocate a buffer
539 */
540
541 skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
542 if (!skb)
543 return NULL;
544
545 skb_reserve(skb, hlen);
546 skb_reset_network_header(skb);
547 arp = skb_put(skb, arp_hdr_len(dev));
548 skb->dev = dev;
549 skb->protocol = htons(ETH_P_ARP);
550 if (!src_hw)
551 src_hw = dev->dev_addr;
552 if (!dest_hw)
553 dest_hw = dev->broadcast;
554
555 /*
556 * Fill the device header for the ARP frame
557 */
558 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
559 goto out;
560
561 /*
562 * Fill out the arp protocol part.
563 *
564 * The arp hardware type should match the device type, except for FDDI,
565 * which (according to RFC 1390) should always equal 1 (Ethernet).
566 */
567 /*
568 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
569 * DIX code for the protocol. Make these device structure fields.
570 */
571 switch (dev->type) {
572 default:
573 arp->ar_hrd = htons(dev->type);
574 arp->ar_pro = htons(ETH_P_IP);
575 break;
576
577#if IS_ENABLED(CONFIG_AX25)
578 case ARPHRD_AX25:
579 arp->ar_hrd = htons(ARPHRD_AX25);
580 arp->ar_pro = htons(AX25_P_IP);
581 break;
582
583#if IS_ENABLED(CONFIG_NETROM)
584 case ARPHRD_NETROM:
585 arp->ar_hrd = htons(ARPHRD_NETROM);
586 arp->ar_pro = htons(AX25_P_IP);
587 break;
588#endif
589#endif
590
591#if IS_ENABLED(CONFIG_FDDI)
592 case ARPHRD_FDDI:
593 arp->ar_hrd = htons(ARPHRD_ETHER);
594 arp->ar_pro = htons(ETH_P_IP);
595 break;
596#endif
597 }
598
599 arp->ar_hln = dev->addr_len;
600 arp->ar_pln = 4;
601 arp->ar_op = htons(type);
602
603 arp_ptr = (unsigned char *)(arp + 1);
604
605 memcpy(arp_ptr, src_hw, dev->addr_len);
606 arp_ptr += dev->addr_len;
607 memcpy(arp_ptr, &src_ip, 4);
608 arp_ptr += 4;
609
610 switch (dev->type) {
611#if IS_ENABLED(CONFIG_FIREWIRE_NET)
612 case ARPHRD_IEEE1394:
613 break;
614#endif
615 default:
616 if (target_hw)
617 memcpy(arp_ptr, target_hw, dev->addr_len);
618 else
619 memset(arp_ptr, 0, dev->addr_len);
620 arp_ptr += dev->addr_len;
621 }
622 memcpy(arp_ptr, &dest_ip, 4);
623
624 return skb;
625
626out:
627 kfree_skb(skb);
628 return NULL;
629}
630EXPORT_SYMBOL(arp_create);
631
632static int arp_xmit_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
633{
634 return dev_queue_xmit(skb);
635}
636
637/*
638 * Send an arp packet.
639 */
640void arp_xmit(struct sk_buff *skb)
641{
642 /* Send it off, maybe filter it using firewalling first. */
643 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT,
644 dev_net(skb->dev), NULL, skb, NULL, skb->dev,
645 arp_xmit_finish);
646}
647EXPORT_SYMBOL(arp_xmit);
648
649static bool arp_is_garp(struct net *net, struct net_device *dev,
650 int *addr_type, __be16 ar_op,
651 __be32 sip, __be32 tip,
652 unsigned char *sha, unsigned char *tha)
653{
654 bool is_garp = tip == sip;
655
656 /* Gratuitous ARP _replies_ also require target hwaddr to be
657 * the same as source.
658 */
659 if (is_garp && ar_op == htons(ARPOP_REPLY))
660 is_garp =
661 /* IPv4 over IEEE 1394 doesn't provide target
662 * hardware address field in its ARP payload.
663 */
664 tha &&
665 !memcmp(tha, sha, dev->addr_len);
666
667 if (is_garp) {
668 *addr_type = inet_addr_type_dev_table(net, dev, sip);
669 if (*addr_type != RTN_UNICAST)
670 is_garp = false;
671 }
672 return is_garp;
673}
674
675/*
676 * Process an arp request.
677 */
678
679static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb)
680{
681 struct net_device *dev = skb->dev;
682 struct in_device *in_dev = __in_dev_get_rcu(dev);
683 struct arphdr *arp;
684 unsigned char *arp_ptr;
685 struct rtable *rt;
686 unsigned char *sha;
687 unsigned char *tha = NULL;
688 __be32 sip, tip;
689 u16 dev_type = dev->type;
690 int addr_type;
691 struct neighbour *n;
692 struct dst_entry *reply_dst = NULL;
693 bool is_garp = false;
694
695 /* arp_rcv below verifies the ARP header and verifies the device
696 * is ARP'able.
697 */
698
699 if (!in_dev)
700 goto out_free_skb;
701
702 arp = arp_hdr(skb);
703
704 switch (dev_type) {
705 default:
706 if (arp->ar_pro != htons(ETH_P_IP) ||
707 htons(dev_type) != arp->ar_hrd)
708 goto out_free_skb;
709 break;
710 case ARPHRD_ETHER:
711 case ARPHRD_FDDI:
712 case ARPHRD_IEEE802:
713 /*
714 * ETHERNET, and Fibre Channel (which are IEEE 802
715 * devices, according to RFC 2625) devices will accept ARP
716 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
717 * This is the case also of FDDI, where the RFC 1390 says that
718 * FDDI devices should accept ARP hardware of (1) Ethernet,
719 * however, to be more robust, we'll accept both 1 (Ethernet)
720 * or 6 (IEEE 802.2)
721 */
722 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
723 arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
724 arp->ar_pro != htons(ETH_P_IP))
725 goto out_free_skb;
726 break;
727 case ARPHRD_AX25:
728 if (arp->ar_pro != htons(AX25_P_IP) ||
729 arp->ar_hrd != htons(ARPHRD_AX25))
730 goto out_free_skb;
731 break;
732 case ARPHRD_NETROM:
733 if (arp->ar_pro != htons(AX25_P_IP) ||
734 arp->ar_hrd != htons(ARPHRD_NETROM))
735 goto out_free_skb;
736 break;
737 }
738
739 /* Understand only these message types */
740
741 if (arp->ar_op != htons(ARPOP_REPLY) &&
742 arp->ar_op != htons(ARPOP_REQUEST))
743 goto out_free_skb;
744
745/*
746 * Extract fields
747 */
748 arp_ptr = (unsigned char *)(arp + 1);
749 sha = arp_ptr;
750 arp_ptr += dev->addr_len;
751 memcpy(&sip, arp_ptr, 4);
752 arp_ptr += 4;
753 switch (dev_type) {
754#if IS_ENABLED(CONFIG_FIREWIRE_NET)
755 case ARPHRD_IEEE1394:
756 break;
757#endif
758 default:
759 tha = arp_ptr;
760 arp_ptr += dev->addr_len;
761 }
762 memcpy(&tip, arp_ptr, 4);
763/*
764 * Check for bad requests for 127.x.x.x and requests for multicast
765 * addresses. If this is one such, delete it.
766 */
767 if (ipv4_is_multicast(tip) ||
768 (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip)))
769 goto out_free_skb;
770
771 /*
772 * For some 802.11 wireless deployments (and possibly other networks),
773 * there will be an ARP proxy and gratuitous ARP frames are attacks
774 * and thus should not be accepted.
775 */
776 if (sip == tip && IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP))
777 goto out_free_skb;
778
779/*
780 * Special case: We must set Frame Relay source Q.922 address
781 */
782 if (dev_type == ARPHRD_DLCI)
783 sha = dev->broadcast;
784
785/*
786 * Process entry. The idea here is we want to send a reply if it is a
787 * request for us or if it is a request for someone else that we hold
788 * a proxy for. We want to add an entry to our cache if it is a reply
789 * to us or if it is a request for our address.
790 * (The assumption for this last is that if someone is requesting our
791 * address, they are probably intending to talk to us, so it saves time
792 * if we cache their address. Their address is also probably not in
793 * our cache, since ours is not in their cache.)
794 *
795 * Putting this another way, we only care about replies if they are to
796 * us, in which case we add them to the cache. For requests, we care
797 * about those for us and those for our proxies. We reply to both,
798 * and in the case of requests for us we add the requester to the arp
799 * cache.
800 */
801
802 if (arp->ar_op == htons(ARPOP_REQUEST) && skb_metadata_dst(skb))
803 reply_dst = (struct dst_entry *)
804 iptunnel_metadata_reply(skb_metadata_dst(skb),
805 GFP_ATOMIC);
806
807 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
808 if (sip == 0) {
809 if (arp->ar_op == htons(ARPOP_REQUEST) &&
810 inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL &&
811 !arp_ignore(in_dev, sip, tip))
812 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip,
813 sha, dev->dev_addr, sha, reply_dst);
814 goto out_consume_skb;
815 }
816
817 if (arp->ar_op == htons(ARPOP_REQUEST) &&
818 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
819
820 rt = skb_rtable(skb);
821 addr_type = rt->rt_type;
822
823 if (addr_type == RTN_LOCAL) {
824 int dont_send;
825
826 dont_send = arp_ignore(in_dev, sip, tip);
827 if (!dont_send && IN_DEV_ARPFILTER(in_dev))
828 dont_send = arp_filter(sip, tip, dev);
829 if (!dont_send) {
830 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
831 if (n) {
832 arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
833 sip, dev, tip, sha,
834 dev->dev_addr, sha,
835 reply_dst);
836 neigh_release(n);
837 }
838 }
839 goto out_consume_skb;
840 } else if (IN_DEV_FORWARD(in_dev)) {
841 if (addr_type == RTN_UNICAST &&
842 (arp_fwd_proxy(in_dev, dev, rt) ||
843 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
844 (rt->dst.dev != dev &&
845 pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
846 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
847 if (n)
848 neigh_release(n);
849
850 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
851 skb->pkt_type == PACKET_HOST ||
852 NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) {
853 arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
854 sip, dev, tip, sha,
855 dev->dev_addr, sha,
856 reply_dst);
857 } else {
858 pneigh_enqueue(&arp_tbl,
859 in_dev->arp_parms, skb);
860 goto out_free_dst;
861 }
862 goto out_consume_skb;
863 }
864 }
865 }
866
867 /* Update our ARP tables */
868
869 n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
870
871 addr_type = -1;
872 if (n || IN_DEV_ARP_ACCEPT(in_dev)) {
873 is_garp = arp_is_garp(net, dev, &addr_type, arp->ar_op,
874 sip, tip, sha, tha);
875 }
876
877 if (IN_DEV_ARP_ACCEPT(in_dev)) {
878 /* Unsolicited ARP is not accepted by default.
879 It is possible, that this option should be enabled for some
880 devices (strip is candidate)
881 */
882 if (!n &&
883 (is_garp ||
884 (arp->ar_op == htons(ARPOP_REPLY) &&
885 (addr_type == RTN_UNICAST ||
886 (addr_type < 0 &&
887 /* postpone calculation to as late as possible */
888 inet_addr_type_dev_table(net, dev, sip) ==
889 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,
903 n->updated +
904 NEIGH_VAR(n->parms, LOCKTIME)) ||
905 is_garp;
906
907 /* Broadcast replies and request packets
908 do not assert neighbour reachability.
909 */
910 if (arp->ar_op != htons(ARPOP_REPLY) ||
911 skb->pkt_type != PACKET_HOST)
912 state = NUD_STALE;
913 neigh_update(n, sha, state,
914 override ? NEIGH_UPDATE_F_OVERRIDE : 0, 0);
915 neigh_release(n);
916 }
917
918out_consume_skb:
919 consume_skb(skb);
920
921out_free_dst:
922 dst_release(reply_dst);
923 return NET_RX_SUCCESS;
924
925out_free_skb:
926 kfree_skb(skb);
927 return NET_RX_DROP;
928}
929
930static void parp_redo(struct sk_buff *skb)
931{
932 arp_process(dev_net(skb->dev), NULL, skb);
933}
934
935
936/*
937 * Receive an arp request from the device layer.
938 */
939
940static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
941 struct packet_type *pt, struct net_device *orig_dev)
942{
943 const struct arphdr *arp;
944
945 /* do not tweak dropwatch on an ARP we will ignore */
946 if (dev->flags & IFF_NOARP ||
947 skb->pkt_type == PACKET_OTHERHOST ||
948 skb->pkt_type == PACKET_LOOPBACK)
949 goto consumeskb;
950
951 skb = skb_share_check(skb, GFP_ATOMIC);
952 if (!skb)
953 goto out_of_mem;
954
955 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
956 if (!pskb_may_pull(skb, arp_hdr_len(dev)))
957 goto freeskb;
958
959 arp = arp_hdr(skb);
960 if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4)
961 goto freeskb;
962
963 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
964
965 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN,
966 dev_net(dev), NULL, skb, dev, NULL,
967 arp_process);
968
969consumeskb:
970 consume_skb(skb);
971 return NET_RX_SUCCESS;
972freeskb:
973 kfree_skb(skb);
974out_of_mem:
975 return NET_RX_DROP;
976}
977
978/*
979 * User level interface (ioctl)
980 */
981
982/*
983 * Set (create) an ARP cache entry.
984 */
985
986static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
987{
988 if (!dev) {
989 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
990 return 0;
991 }
992 if (__in_dev_get_rtnl(dev)) {
993 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
994 return 0;
995 }
996 return -ENXIO;
997}
998
999static int arp_req_set_public(struct net *net, struct arpreq *r,
1000 struct net_device *dev)
1001{
1002 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1003 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1004
1005 if (mask && mask != htonl(0xFFFFFFFF))
1006 return -EINVAL;
1007 if (!dev && (r->arp_flags & ATF_COM)) {
1008 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family,
1009 r->arp_ha.sa_data);
1010 if (!dev)
1011 return -ENODEV;
1012 }
1013 if (mask) {
1014 if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1))
1015 return -ENOBUFS;
1016 return 0;
1017 }
1018
1019 return arp_req_set_proxy(net, dev, 1);
1020}
1021
1022static int arp_req_set(struct net *net, struct arpreq *r,
1023 struct net_device *dev)
1024{
1025 __be32 ip;
1026 struct neighbour *neigh;
1027 int err;
1028
1029 if (r->arp_flags & ATF_PUBL)
1030 return arp_req_set_public(net, r, dev);
1031
1032 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1033 if (r->arp_flags & ATF_PERM)
1034 r->arp_flags |= ATF_COM;
1035 if (!dev) {
1036 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1037
1038 if (IS_ERR(rt))
1039 return PTR_ERR(rt);
1040 dev = rt->dst.dev;
1041 ip_rt_put(rt);
1042 if (!dev)
1043 return -EINVAL;
1044 }
1045 switch (dev->type) {
1046#if IS_ENABLED(CONFIG_FDDI)
1047 case ARPHRD_FDDI:
1048 /*
1049 * According to RFC 1390, FDDI devices should accept ARP
1050 * hardware types of 1 (Ethernet). However, to be more
1051 * robust, we'll accept hardware types of either 1 (Ethernet)
1052 * or 6 (IEEE 802.2).
1053 */
1054 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1055 r->arp_ha.sa_family != ARPHRD_ETHER &&
1056 r->arp_ha.sa_family != ARPHRD_IEEE802)
1057 return -EINVAL;
1058 break;
1059#endif
1060 default:
1061 if (r->arp_ha.sa_family != dev->type)
1062 return -EINVAL;
1063 break;
1064 }
1065
1066 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1067 err = PTR_ERR(neigh);
1068 if (!IS_ERR(neigh)) {
1069 unsigned int state = NUD_STALE;
1070 if (r->arp_flags & ATF_PERM)
1071 state = NUD_PERMANENT;
1072 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ?
1073 r->arp_ha.sa_data : NULL, state,
1074 NEIGH_UPDATE_F_OVERRIDE |
1075 NEIGH_UPDATE_F_ADMIN, 0);
1076 neigh_release(neigh);
1077 }
1078 return err;
1079}
1080
1081static unsigned int arp_state_to_flags(struct neighbour *neigh)
1082{
1083 if (neigh->nud_state&NUD_PERMANENT)
1084 return ATF_PERM | ATF_COM;
1085 else if (neigh->nud_state&NUD_VALID)
1086 return ATF_COM;
1087 else
1088 return 0;
1089}
1090
1091/*
1092 * Get an ARP cache entry.
1093 */
1094
1095static int arp_req_get(struct arpreq *r, struct net_device *dev)
1096{
1097 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1098 struct neighbour *neigh;
1099 int err = -ENXIO;
1100
1101 neigh = neigh_lookup(&arp_tbl, &ip, dev);
1102 if (neigh) {
1103 if (!(neigh->nud_state & NUD_NOARP)) {
1104 read_lock_bh(&neigh->lock);
1105 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
1106 r->arp_flags = arp_state_to_flags(neigh);
1107 read_unlock_bh(&neigh->lock);
1108 r->arp_ha.sa_family = dev->type;
1109 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1110 err = 0;
1111 }
1112 neigh_release(neigh);
1113 }
1114 return err;
1115}
1116
1117static int arp_invalidate(struct net_device *dev, __be32 ip)
1118{
1119 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
1120 int err = -ENXIO;
1121 struct neigh_table *tbl = &arp_tbl;
1122
1123 if (neigh) {
1124 if (neigh->nud_state & ~NUD_NOARP)
1125 err = neigh_update(neigh, NULL, NUD_FAILED,
1126 NEIGH_UPDATE_F_OVERRIDE|
1127 NEIGH_UPDATE_F_ADMIN, 0);
1128 write_lock_bh(&tbl->lock);
1129 neigh_release(neigh);
1130 neigh_remove_one(neigh, tbl);
1131 write_unlock_bh(&tbl->lock);
1132 }
1133
1134 return err;
1135}
1136
1137static int arp_req_delete_public(struct net *net, struct arpreq *r,
1138 struct net_device *dev)
1139{
1140 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1141 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1142
1143 if (mask == htonl(0xFFFFFFFF))
1144 return pneigh_delete(&arp_tbl, net, &ip, dev);
1145
1146 if (mask)
1147 return -EINVAL;
1148
1149 return arp_req_set_proxy(net, dev, 0);
1150}
1151
1152static int arp_req_delete(struct net *net, struct arpreq *r,
1153 struct net_device *dev)
1154{
1155 __be32 ip;
1156
1157 if (r->arp_flags & ATF_PUBL)
1158 return arp_req_delete_public(net, r, dev);
1159
1160 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1161 if (!dev) {
1162 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1163 if (IS_ERR(rt))
1164 return PTR_ERR(rt);
1165 dev = rt->dst.dev;
1166 ip_rt_put(rt);
1167 if (!dev)
1168 return -EINVAL;
1169 }
1170 return arp_invalidate(dev, ip);
1171}
1172
1173/*
1174 * Handle an ARP layer I/O control request.
1175 */
1176
1177int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1178{
1179 int err;
1180 struct arpreq r;
1181 struct net_device *dev = NULL;
1182
1183 switch (cmd) {
1184 case SIOCDARP:
1185 case SIOCSARP:
1186 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1187 return -EPERM;
1188 /* fall through */
1189 case SIOCGARP:
1190 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1191 if (err)
1192 return -EFAULT;
1193 break;
1194 default:
1195 return -EINVAL;
1196 }
1197
1198 if (r.arp_pa.sa_family != AF_INET)
1199 return -EPFNOSUPPORT;
1200
1201 if (!(r.arp_flags & ATF_PUBL) &&
1202 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1203 return -EINVAL;
1204 if (!(r.arp_flags & ATF_NETMASK))
1205 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1206 htonl(0xFFFFFFFFUL);
1207 rtnl_lock();
1208 if (r.arp_dev[0]) {
1209 err = -ENODEV;
1210 dev = __dev_get_by_name(net, r.arp_dev);
1211 if (!dev)
1212 goto out;
1213
1214 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1215 if (!r.arp_ha.sa_family)
1216 r.arp_ha.sa_family = dev->type;
1217 err = -EINVAL;
1218 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1219 goto out;
1220 } else if (cmd == SIOCGARP) {
1221 err = -ENODEV;
1222 goto out;
1223 }
1224
1225 switch (cmd) {
1226 case SIOCDARP:
1227 err = arp_req_delete(net, &r, dev);
1228 break;
1229 case SIOCSARP:
1230 err = arp_req_set(net, &r, dev);
1231 break;
1232 case SIOCGARP:
1233 err = arp_req_get(&r, dev);
1234 break;
1235 }
1236out:
1237 rtnl_unlock();
1238 if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
1239 err = -EFAULT;
1240 return err;
1241}
1242
1243static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1244 void *ptr)
1245{
1246 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
1247 struct netdev_notifier_change_info *change_info;
1248
1249 switch (event) {
1250 case NETDEV_CHANGEADDR:
1251 neigh_changeaddr(&arp_tbl, dev);
1252 rt_cache_flush(dev_net(dev));
1253 break;
1254 case NETDEV_CHANGE:
1255 change_info = ptr;
1256 if (change_info->flags_changed & IFF_NOARP)
1257 neigh_changeaddr(&arp_tbl, dev);
1258 break;
1259 default:
1260 break;
1261 }
1262
1263 return NOTIFY_DONE;
1264}
1265
1266static struct notifier_block arp_netdev_notifier = {
1267 .notifier_call = arp_netdev_event,
1268};
1269
1270/* Note, that it is not on notifier chain.
1271 It is necessary, that this routine was called after route cache will be
1272 flushed.
1273 */
1274void arp_ifdown(struct net_device *dev)
1275{
1276 neigh_ifdown(&arp_tbl, dev);
1277}
1278
1279
1280/*
1281 * Called once on startup.
1282 */
1283
1284static struct packet_type arp_packet_type __read_mostly = {
1285 .type = cpu_to_be16(ETH_P_ARP),
1286 .func = arp_rcv,
1287};
1288
1289static int arp_proc_init(void);
1290
1291void __init arp_init(void)
1292{
1293 neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl);
1294
1295 dev_add_pack(&arp_packet_type);
1296 arp_proc_init();
1297#ifdef CONFIG_SYSCTL
1298 neigh_sysctl_register(NULL, &arp_tbl.parms, NULL);
1299#endif
1300 register_netdevice_notifier(&arp_netdev_notifier);
1301}
1302
1303#ifdef CONFIG_PROC_FS
1304#if IS_ENABLED(CONFIG_AX25)
1305
1306/* ------------------------------------------------------------------------ */
1307/*
1308 * ax25 -> ASCII conversion
1309 */
1310static void ax2asc2(ax25_address *a, char *buf)
1311{
1312 char c, *s;
1313 int n;
1314
1315 for (n = 0, s = buf; n < 6; n++) {
1316 c = (a->ax25_call[n] >> 1) & 0x7F;
1317
1318 if (c != ' ')
1319 *s++ = c;
1320 }
1321
1322 *s++ = '-';
1323 n = (a->ax25_call[6] >> 1) & 0x0F;
1324 if (n > 9) {
1325 *s++ = '1';
1326 n -= 10;
1327 }
1328
1329 *s++ = n + '0';
1330 *s++ = '\0';
1331
1332 if (*buf == '\0' || *buf == '-') {
1333 buf[0] = '*';
1334 buf[1] = '\0';
1335 }
1336}
1337#endif /* CONFIG_AX25 */
1338
1339#define HBUFFERLEN 30
1340
1341static void arp_format_neigh_entry(struct seq_file *seq,
1342 struct neighbour *n)
1343{
1344 char hbuffer[HBUFFERLEN];
1345 int k, j;
1346 char tbuf[16];
1347 struct net_device *dev = n->dev;
1348 int hatype = dev->type;
1349
1350 read_lock(&n->lock);
1351 /* Convert hardware address to XX:XX:XX:XX ... form. */
1352#if IS_ENABLED(CONFIG_AX25)
1353 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1354 ax2asc2((ax25_address *)n->ha, hbuffer);
1355 else {
1356#endif
1357 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1358 hbuffer[k++] = hex_asc_hi(n->ha[j]);
1359 hbuffer[k++] = hex_asc_lo(n->ha[j]);
1360 hbuffer[k++] = ':';
1361 }
1362 if (k != 0)
1363 --k;
1364 hbuffer[k] = 0;
1365#if IS_ENABLED(CONFIG_AX25)
1366 }
1367#endif
1368 sprintf(tbuf, "%pI4", n->primary_key);
1369 seq_printf(seq, "%-16s 0x%-10x0x%-10x%-17s * %s\n",
1370 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1371 read_unlock(&n->lock);
1372}
1373
1374static void arp_format_pneigh_entry(struct seq_file *seq,
1375 struct pneigh_entry *n)
1376{
1377 struct net_device *dev = n->dev;
1378 int hatype = dev ? dev->type : 0;
1379 char tbuf[16];
1380
1381 sprintf(tbuf, "%pI4", n->key);
1382 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1383 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1384 dev ? dev->name : "*");
1385}
1386
1387static int arp_seq_show(struct seq_file *seq, void *v)
1388{
1389 if (v == SEQ_START_TOKEN) {
1390 seq_puts(seq, "IP address HW type Flags "
1391 "HW address Mask Device\n");
1392 } else {
1393 struct neigh_seq_state *state = seq->private;
1394
1395 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1396 arp_format_pneigh_entry(seq, v);
1397 else
1398 arp_format_neigh_entry(seq, v);
1399 }
1400
1401 return 0;
1402}
1403
1404static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1405{
1406 /* Don't want to confuse "arp -a" w/ magic entries,
1407 * so we tell the generic iterator to skip NUD_NOARP.
1408 */
1409 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1410}
1411
1412/* ------------------------------------------------------------------------ */
1413
1414static const struct seq_operations arp_seq_ops = {
1415 .start = arp_seq_start,
1416 .next = neigh_seq_next,
1417 .stop = neigh_seq_stop,
1418 .show = arp_seq_show,
1419};
1420
1421static int arp_seq_open(struct inode *inode, struct file *file)
1422{
1423 return seq_open_net(inode, file, &arp_seq_ops,
1424 sizeof(struct neigh_seq_state));
1425}
1426
1427static const struct file_operations arp_seq_fops = {
1428 .open = arp_seq_open,
1429 .read = seq_read,
1430 .llseek = seq_lseek,
1431 .release = seq_release_net,
1432};
1433
1434
1435static int __net_init arp_net_init(struct net *net)
1436{
1437 if (!proc_create("arp", 0444, net->proc_net, &arp_seq_fops))
1438 return -ENOMEM;
1439 return 0;
1440}
1441
1442static void __net_exit arp_net_exit(struct net *net)
1443{
1444 remove_proc_entry("arp", net->proc_net);
1445}
1446
1447static struct pernet_operations arp_net_ops = {
1448 .init = arp_net_init,
1449 .exit = arp_net_exit,
1450};
1451
1452static int __init arp_proc_init(void)
1453{
1454 return register_pernet_subsys(&arp_net_ops);
1455}
1456
1457#else /* CONFIG_PROC_FS */
1458
1459static int __init arp_proc_init(void)
1460{
1461 return 0;
1462}
1463
1464#endif /* CONFIG_PROC_FS */
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* linux/net/ipv4/arp.c
3 *
4 * Copyright (C) 1994 by Florian La Roche
5 *
6 * This module implements the Address Resolution Protocol ARP (RFC 826),
7 * which is used to convert IP addresses (or in the future maybe other
8 * high-level addresses) into a low-level hardware address (like an Ethernet
9 * address).
10 *
11 * Fixes:
12 * Alan Cox : Removed the Ethernet assumptions in
13 * Florian's code
14 * Alan Cox : Fixed some small errors in the ARP
15 * logic
16 * Alan Cox : Allow >4K in /proc
17 * Alan Cox : Make ARP add its own protocol entry
18 * Ross Martin : Rewrote arp_rcv() and arp_get_info()
19 * Stephen Henson : Add AX25 support to arp_get_info()
20 * Alan Cox : Drop data when a device is downed.
21 * Alan Cox : Use init_timer().
22 * Alan Cox : Double lock fixes.
23 * Martin Seine : Move the arphdr structure
24 * to if_arp.h for compatibility.
25 * with BSD based programs.
26 * Andrew Tridgell : Added ARP netmask code and
27 * re-arranged proxy handling.
28 * Alan Cox : Changed to use notifiers.
29 * Niibe Yutaka : Reply for this device or proxies only.
30 * Alan Cox : Don't proxy across hardware types!
31 * Jonathan Naylor : Added support for NET/ROM.
32 * Mike Shaver : RFC1122 checks.
33 * Jonathan Naylor : Only lookup the hardware address for
34 * the correct hardware type.
35 * Germano Caronni : Assorted subtle races.
36 * Craig Schlenter : Don't modify permanent entry
37 * during arp_rcv.
38 * Russ Nelson : Tidied up a few bits.
39 * Alexey Kuznetsov: Major changes to caching and behaviour,
40 * eg intelligent arp probing and
41 * generation
42 * of host down events.
43 * Alan Cox : Missing unlock in device events.
44 * Eckes : ARP ioctl control errors.
45 * Alexey Kuznetsov: Arp free fix.
46 * Manuel Rodriguez: Gratuitous ARP.
47 * Jonathan Layes : Added arpd support through kerneld
48 * message queue (960314)
49 * Mike Shaver : /proc/sys/net/ipv4/arp_* support
50 * Mike McLagan : Routing by source
51 * Stuart Cheshire : Metricom and grat arp fixes
52 * *** FOR 2.1 clean this up ***
53 * Lawrence V. Stefani: (08/12/96) Added FDDI support.
54 * Alan Cox : Took the AP1000 nasty FDDI hack and
55 * folded into the mainstream FDDI code.
56 * Ack spit, Linus how did you allow that
57 * one in...
58 * Jes Sorensen : Make FDDI work again in 2.1.x and
59 * clean up the APFDDI & gen. FDDI bits.
60 * Alexey Kuznetsov: new arp state machine;
61 * now it is in net/core/neighbour.c.
62 * Krzysztof Halasa: Added Frame Relay ARP support.
63 * Arnaldo C. Melo : convert /proc/net/arp to seq_file
64 * Shmulik Hen: Split arp_send to arp_create and
65 * arp_xmit so intermediate drivers like
66 * bonding can change the skb before
67 * sending (e.g. insert 8021q tag).
68 * Harald Welte : convert to make use of jenkins hash
69 * Jesper D. Brouer: Proxy ARP PVLAN RFC 3069 support.
70 */
71
72#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
73
74#include <linux/module.h>
75#include <linux/types.h>
76#include <linux/string.h>
77#include <linux/kernel.h>
78#include <linux/capability.h>
79#include <linux/socket.h>
80#include <linux/sockios.h>
81#include <linux/errno.h>
82#include <linux/in.h>
83#include <linux/mm.h>
84#include <linux/inet.h>
85#include <linux/inetdevice.h>
86#include <linux/netdevice.h>
87#include <linux/etherdevice.h>
88#include <linux/fddidevice.h>
89#include <linux/if_arp.h>
90#include <linux/skbuff.h>
91#include <linux/proc_fs.h>
92#include <linux/seq_file.h>
93#include <linux/stat.h>
94#include <linux/init.h>
95#include <linux/net.h>
96#include <linux/rcupdate.h>
97#include <linux/slab.h>
98#ifdef CONFIG_SYSCTL
99#include <linux/sysctl.h>
100#endif
101
102#include <net/net_namespace.h>
103#include <net/ip.h>
104#include <net/icmp.h>
105#include <net/route.h>
106#include <net/protocol.h>
107#include <net/tcp.h>
108#include <net/sock.h>
109#include <net/arp.h>
110#include <net/ax25.h>
111#include <net/netrom.h>
112#include <net/dst_metadata.h>
113#include <net/ip_tunnels.h>
114
115#include <linux/uaccess.h>
116
117#include <linux/netfilter_arp.h>
118
119/*
120 * Interface to generic neighbour cache.
121 */
122static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd);
123static bool arp_key_eq(const struct neighbour *n, const void *pkey);
124static int arp_constructor(struct neighbour *neigh);
125static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
126static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
127static void parp_redo(struct sk_buff *skb);
128static int arp_is_multicast(const void *pkey);
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
152struct neigh_table arp_tbl = {
153 .family = AF_INET,
154 .key_len = 4,
155 .protocol = cpu_to_be16(ETH_P_IP),
156 .hash = arp_hash,
157 .key_eq = arp_key_eq,
158 .constructor = arp_constructor,
159 .proxy_redo = parp_redo,
160 .is_multicast = arp_is_multicast,
161 .id = "arp_cache",
162 .parms = {
163 .tbl = &arp_tbl,
164 .reachable_time = 30 * HZ,
165 .data = {
166 [NEIGH_VAR_MCAST_PROBES] = 3,
167 [NEIGH_VAR_UCAST_PROBES] = 3,
168 [NEIGH_VAR_RETRANS_TIME] = 1 * HZ,
169 [NEIGH_VAR_BASE_REACHABLE_TIME] = 30 * HZ,
170 [NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ,
171 [NEIGH_VAR_INTERVAL_PROBE_TIME_MS] = 5 * HZ,
172 [NEIGH_VAR_GC_STALETIME] = 60 * HZ,
173 [NEIGH_VAR_QUEUE_LEN_BYTES] = SK_WMEM_MAX,
174 [NEIGH_VAR_PROXY_QLEN] = 64,
175 [NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ,
176 [NEIGH_VAR_PROXY_DELAY] = (8 * HZ) / 10,
177 [NEIGH_VAR_LOCKTIME] = 1 * HZ,
178 },
179 },
180 .gc_interval = 30 * HZ,
181 .gc_thresh1 = 128,
182 .gc_thresh2 = 512,
183 .gc_thresh3 = 1024,
184};
185EXPORT_SYMBOL(arp_tbl);
186
187int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir)
188{
189 switch (dev->type) {
190 case ARPHRD_ETHER:
191 case ARPHRD_FDDI:
192 case ARPHRD_IEEE802:
193 ip_eth_mc_map(addr, haddr);
194 return 0;
195 case ARPHRD_INFINIBAND:
196 ip_ib_mc_map(addr, dev->broadcast, haddr);
197 return 0;
198 case ARPHRD_IPGRE:
199 ip_ipgre_mc_map(addr, dev->broadcast, haddr);
200 return 0;
201 default:
202 if (dir) {
203 memcpy(haddr, dev->broadcast, dev->addr_len);
204 return 0;
205 }
206 }
207 return -EINVAL;
208}
209
210
211static u32 arp_hash(const void *pkey,
212 const struct net_device *dev,
213 __u32 *hash_rnd)
214{
215 return arp_hashfn(pkey, dev, hash_rnd);
216}
217
218static bool arp_key_eq(const struct neighbour *neigh, const void *pkey)
219{
220 return neigh_key_eq32(neigh, pkey);
221}
222
223static int arp_constructor(struct neighbour *neigh)
224{
225 __be32 addr;
226 struct net_device *dev = neigh->dev;
227 struct in_device *in_dev;
228 struct neigh_parms *parms;
229 u32 inaddr_any = INADDR_ANY;
230
231 if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT))
232 memcpy(neigh->primary_key, &inaddr_any, arp_tbl.key_len);
233
234 addr = *(__be32 *)neigh->primary_key;
235 rcu_read_lock();
236 in_dev = __in_dev_get_rcu(dev);
237 if (!in_dev) {
238 rcu_read_unlock();
239 return -EINVAL;
240 }
241
242 neigh->type = inet_addr_type_dev_table(dev_net(dev), dev, addr);
243
244 parms = in_dev->arp_parms;
245 __neigh_parms_put(neigh->parms);
246 neigh->parms = neigh_parms_clone(parms);
247 rcu_read_unlock();
248
249 if (!dev->header_ops) {
250 neigh->nud_state = NUD_NOARP;
251 neigh->ops = &arp_direct_ops;
252 neigh->output = neigh_direct_output;
253 } else {
254 /* Good devices (checked by reading texts, but only Ethernet is
255 tested)
256
257 ARPHRD_ETHER: (ethernet, apfddi)
258 ARPHRD_FDDI: (fddi)
259 ARPHRD_IEEE802: (tr)
260 ARPHRD_METRICOM: (strip)
261 ARPHRD_ARCNET:
262 etc. etc. etc.
263
264 ARPHRD_IPDDP will also work, if author repairs it.
265 I did not it, because this driver does not work even
266 in old paradigm.
267 */
268
269 if (neigh->type == RTN_MULTICAST) {
270 neigh->nud_state = NUD_NOARP;
271 arp_mc_map(addr, neigh->ha, dev, 1);
272 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) {
273 neigh->nud_state = NUD_NOARP;
274 memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
275 } else if (neigh->type == RTN_BROADCAST ||
276 (dev->flags & IFF_POINTOPOINT)) {
277 neigh->nud_state = NUD_NOARP;
278 memcpy(neigh->ha, dev->broadcast, dev->addr_len);
279 }
280
281 if (dev->header_ops->cache)
282 neigh->ops = &arp_hh_ops;
283 else
284 neigh->ops = &arp_generic_ops;
285
286 if (neigh->nud_state & NUD_VALID)
287 neigh->output = neigh->ops->connected_output;
288 else
289 neigh->output = neigh->ops->output;
290 }
291 return 0;
292}
293
294static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
295{
296 dst_link_failure(skb);
297 kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_FAILED);
298}
299
300/* Create and send an arp packet. */
301static void arp_send_dst(int type, int ptype, __be32 dest_ip,
302 struct net_device *dev, __be32 src_ip,
303 const unsigned char *dest_hw,
304 const unsigned char *src_hw,
305 const unsigned char *target_hw,
306 struct dst_entry *dst)
307{
308 struct sk_buff *skb;
309
310 /* arp on this interface. */
311 if (dev->flags & IFF_NOARP)
312 return;
313
314 skb = arp_create(type, ptype, dest_ip, dev, src_ip,
315 dest_hw, src_hw, target_hw);
316 if (!skb)
317 return;
318
319 skb_dst_set(skb, dst_clone(dst));
320 arp_xmit(skb);
321}
322
323void arp_send(int type, int ptype, __be32 dest_ip,
324 struct net_device *dev, __be32 src_ip,
325 const unsigned char *dest_hw, const unsigned char *src_hw,
326 const unsigned char *target_hw)
327{
328 arp_send_dst(type, ptype, dest_ip, dev, src_ip, dest_hw, src_hw,
329 target_hw, NULL);
330}
331EXPORT_SYMBOL(arp_send);
332
333static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
334{
335 __be32 saddr = 0;
336 u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL;
337 struct net_device *dev = neigh->dev;
338 __be32 target = *(__be32 *)neigh->primary_key;
339 int probes = atomic_read(&neigh->probes);
340 struct in_device *in_dev;
341 struct dst_entry *dst = NULL;
342
343 rcu_read_lock();
344 in_dev = __in_dev_get_rcu(dev);
345 if (!in_dev) {
346 rcu_read_unlock();
347 return;
348 }
349 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
350 default:
351 case 0: /* By default announce any local IP */
352 if (skb && inet_addr_type_dev_table(dev_net(dev), dev,
353 ip_hdr(skb)->saddr) == RTN_LOCAL)
354 saddr = ip_hdr(skb)->saddr;
355 break;
356 case 1: /* Restrict announcements of saddr in same subnet */
357 if (!skb)
358 break;
359 saddr = ip_hdr(skb)->saddr;
360 if (inet_addr_type_dev_table(dev_net(dev), dev,
361 saddr) == RTN_LOCAL) {
362 /* saddr should be known to target */
363 if (inet_addr_onlink(in_dev, target, saddr))
364 break;
365 }
366 saddr = 0;
367 break;
368 case 2: /* Avoid secondary IPs, get a primary/preferred one */
369 break;
370 }
371 rcu_read_unlock();
372
373 if (!saddr)
374 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
375
376 probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES);
377 if (probes < 0) {
378 if (!(READ_ONCE(neigh->nud_state) & NUD_VALID))
379 pr_debug("trying to ucast probe in NUD_INVALID\n");
380 neigh_ha_snapshot(dst_ha, neigh, dev);
381 dst_hw = dst_ha;
382 } else {
383 probes -= NEIGH_VAR(neigh->parms, APP_PROBES);
384 if (probes < 0) {
385 neigh_app_ns(neigh);
386 return;
387 }
388 }
389
390 if (skb && !(dev->priv_flags & IFF_XMIT_DST_RELEASE))
391 dst = skb_dst(skb);
392 arp_send_dst(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
393 dst_hw, dev->dev_addr, NULL, dst);
394}
395
396static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip)
397{
398 struct net *net = dev_net(in_dev->dev);
399 int scope;
400
401 switch (IN_DEV_ARP_IGNORE(in_dev)) {
402 case 0: /* Reply, the tip is already validated */
403 return 0;
404 case 1: /* Reply only if tip is configured on the incoming interface */
405 sip = 0;
406 scope = RT_SCOPE_HOST;
407 break;
408 case 2: /*
409 * Reply only if tip is configured on the incoming interface
410 * and is in same subnet as sip
411 */
412 scope = RT_SCOPE_HOST;
413 break;
414 case 3: /* Do not reply for scope host addresses */
415 sip = 0;
416 scope = RT_SCOPE_LINK;
417 in_dev = NULL;
418 break;
419 case 4: /* Reserved */
420 case 5:
421 case 6:
422 case 7:
423 return 0;
424 case 8: /* Do not reply */
425 return 1;
426 default:
427 return 0;
428 }
429 return !inet_confirm_addr(net, in_dev, sip, tip, scope);
430}
431
432static int arp_accept(struct in_device *in_dev, __be32 sip)
433{
434 struct net *net = dev_net(in_dev->dev);
435 int scope = RT_SCOPE_LINK;
436
437 switch (IN_DEV_ARP_ACCEPT(in_dev)) {
438 case 0: /* Don't create new entries from garp */
439 return 0;
440 case 1: /* Create new entries from garp */
441 return 1;
442 case 2: /* Create a neighbor in the arp table only if sip
443 * is in the same subnet as an address configured
444 * on the interface that received the garp message
445 */
446 return !!inet_confirm_addr(net, in_dev, sip, 0, scope);
447 default:
448 return 0;
449 }
450}
451
452static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
453{
454 struct rtable *rt;
455 int flag = 0;
456 /*unsigned long now; */
457 struct net *net = dev_net(dev);
458
459 rt = ip_route_output(net, sip, tip, 0, l3mdev_master_ifindex_rcu(dev),
460 RT_SCOPE_UNIVERSE);
461 if (IS_ERR(rt))
462 return 1;
463 if (rt->dst.dev != dev) {
464 __NET_INC_STATS(net, LINUX_MIB_ARPFILTER);
465 flag = 1;
466 }
467 ip_rt_put(rt);
468 return flag;
469}
470
471/*
472 * Check if we can use proxy ARP for this path
473 */
474static inline int arp_fwd_proxy(struct in_device *in_dev,
475 struct net_device *dev, struct rtable *rt)
476{
477 struct in_device *out_dev;
478 int imi, omi = -1;
479
480 if (rt->dst.dev == dev)
481 return 0;
482
483 if (!IN_DEV_PROXY_ARP(in_dev))
484 return 0;
485 imi = IN_DEV_MEDIUM_ID(in_dev);
486 if (imi == 0)
487 return 1;
488 if (imi == -1)
489 return 0;
490
491 /* place to check for proxy_arp for routes */
492
493 out_dev = __in_dev_get_rcu(rt->dst.dev);
494 if (out_dev)
495 omi = IN_DEV_MEDIUM_ID(out_dev);
496
497 return omi != imi && omi != -1;
498}
499
500/*
501 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
502 *
503 * RFC3069 supports proxy arp replies back to the same interface. This
504 * is done to support (ethernet) switch features, like RFC 3069, where
505 * the individual ports are not allowed to communicate with each
506 * other, BUT they are allowed to talk to the upstream router. As
507 * described in RFC 3069, it is possible to allow these hosts to
508 * communicate through the upstream router, by proxy_arp'ing.
509 *
510 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
511 *
512 * This technology is known by different names:
513 * In RFC 3069 it is called VLAN Aggregation.
514 * Cisco and Allied Telesyn call it Private VLAN.
515 * Hewlett-Packard call it Source-Port filtering or port-isolation.
516 * Ericsson call it MAC-Forced Forwarding (RFC Draft).
517 *
518 */
519static inline int arp_fwd_pvlan(struct in_device *in_dev,
520 struct net_device *dev, struct rtable *rt,
521 __be32 sip, __be32 tip)
522{
523 /* Private VLAN is only concerned about the same ethernet segment */
524 if (rt->dst.dev != dev)
525 return 0;
526
527 /* Don't reply on self probes (often done by windowz boxes)*/
528 if (sip == tip)
529 return 0;
530
531 if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
532 return 1;
533 else
534 return 0;
535}
536
537/*
538 * Interface to link layer: send routine and receive handler.
539 */
540
541/*
542 * Create an arp packet. If dest_hw is not set, we create a broadcast
543 * message.
544 */
545struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
546 struct net_device *dev, __be32 src_ip,
547 const unsigned char *dest_hw,
548 const unsigned char *src_hw,
549 const unsigned char *target_hw)
550{
551 struct sk_buff *skb;
552 struct arphdr *arp;
553 unsigned char *arp_ptr;
554 int hlen = LL_RESERVED_SPACE(dev);
555 int tlen = dev->needed_tailroom;
556
557 /*
558 * Allocate a buffer
559 */
560
561 skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
562 if (!skb)
563 return NULL;
564
565 skb_reserve(skb, hlen);
566 skb_reset_network_header(skb);
567 arp = skb_put(skb, arp_hdr_len(dev));
568 skb->dev = dev;
569 skb->protocol = htons(ETH_P_ARP);
570 if (!src_hw)
571 src_hw = dev->dev_addr;
572 if (!dest_hw)
573 dest_hw = dev->broadcast;
574
575 /*
576 * Fill the device header for the ARP frame
577 */
578 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
579 goto out;
580
581 /*
582 * Fill out the arp protocol part.
583 *
584 * The arp hardware type should match the device type, except for FDDI,
585 * which (according to RFC 1390) should always equal 1 (Ethernet).
586 */
587 /*
588 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
589 * DIX code for the protocol. Make these device structure fields.
590 */
591 switch (dev->type) {
592 default:
593 arp->ar_hrd = htons(dev->type);
594 arp->ar_pro = htons(ETH_P_IP);
595 break;
596
597#if IS_ENABLED(CONFIG_AX25)
598 case ARPHRD_AX25:
599 arp->ar_hrd = htons(ARPHRD_AX25);
600 arp->ar_pro = htons(AX25_P_IP);
601 break;
602
603#if IS_ENABLED(CONFIG_NETROM)
604 case ARPHRD_NETROM:
605 arp->ar_hrd = htons(ARPHRD_NETROM);
606 arp->ar_pro = htons(AX25_P_IP);
607 break;
608#endif
609#endif
610
611#if IS_ENABLED(CONFIG_FDDI)
612 case ARPHRD_FDDI:
613 arp->ar_hrd = htons(ARPHRD_ETHER);
614 arp->ar_pro = htons(ETH_P_IP);
615 break;
616#endif
617 }
618
619 arp->ar_hln = dev->addr_len;
620 arp->ar_pln = 4;
621 arp->ar_op = htons(type);
622
623 arp_ptr = (unsigned char *)(arp + 1);
624
625 memcpy(arp_ptr, src_hw, dev->addr_len);
626 arp_ptr += dev->addr_len;
627 memcpy(arp_ptr, &src_ip, 4);
628 arp_ptr += 4;
629
630 switch (dev->type) {
631#if IS_ENABLED(CONFIG_FIREWIRE_NET)
632 case ARPHRD_IEEE1394:
633 break;
634#endif
635 default:
636 if (target_hw)
637 memcpy(arp_ptr, target_hw, dev->addr_len);
638 else
639 memset(arp_ptr, 0, dev->addr_len);
640 arp_ptr += dev->addr_len;
641 }
642 memcpy(arp_ptr, &dest_ip, 4);
643
644 return skb;
645
646out:
647 kfree_skb(skb);
648 return NULL;
649}
650EXPORT_SYMBOL(arp_create);
651
652static int arp_xmit_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
653{
654 return dev_queue_xmit(skb);
655}
656
657/*
658 * Send an arp packet.
659 */
660void arp_xmit(struct sk_buff *skb)
661{
662 rcu_read_lock();
663 /* Send it off, maybe filter it using firewalling first. */
664 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT,
665 dev_net_rcu(skb->dev), NULL, skb, NULL, skb->dev,
666 arp_xmit_finish);
667 rcu_read_unlock();
668}
669EXPORT_SYMBOL(arp_xmit);
670
671static bool arp_is_garp(struct net *net, struct net_device *dev,
672 int *addr_type, __be16 ar_op,
673 __be32 sip, __be32 tip,
674 unsigned char *sha, unsigned char *tha)
675{
676 bool is_garp = tip == sip;
677
678 /* Gratuitous ARP _replies_ also require target hwaddr to be
679 * the same as source.
680 */
681 if (is_garp && ar_op == htons(ARPOP_REPLY))
682 is_garp =
683 /* IPv4 over IEEE 1394 doesn't provide target
684 * hardware address field in its ARP payload.
685 */
686 tha &&
687 !memcmp(tha, sha, dev->addr_len);
688
689 if (is_garp) {
690 *addr_type = inet_addr_type_dev_table(net, dev, sip);
691 if (*addr_type != RTN_UNICAST)
692 is_garp = false;
693 }
694 return is_garp;
695}
696
697/*
698 * Process an arp request.
699 */
700
701static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb)
702{
703 struct net_device *dev = skb->dev;
704 struct in_device *in_dev = __in_dev_get_rcu(dev);
705 struct arphdr *arp;
706 unsigned char *arp_ptr;
707 struct rtable *rt;
708 unsigned char *sha;
709 unsigned char *tha = NULL;
710 __be32 sip, tip;
711 u16 dev_type = dev->type;
712 int addr_type;
713 struct neighbour *n;
714 struct dst_entry *reply_dst = NULL;
715 bool is_garp = false;
716
717 /* arp_rcv below verifies the ARP header and verifies the device
718 * is ARP'able.
719 */
720
721 if (!in_dev)
722 goto out_free_skb;
723
724 arp = arp_hdr(skb);
725
726 switch (dev_type) {
727 default:
728 if (arp->ar_pro != htons(ETH_P_IP) ||
729 htons(dev_type) != arp->ar_hrd)
730 goto out_free_skb;
731 break;
732 case ARPHRD_ETHER:
733 case ARPHRD_FDDI:
734 case ARPHRD_IEEE802:
735 /*
736 * ETHERNET, and Fibre Channel (which are IEEE 802
737 * devices, according to RFC 2625) devices will accept ARP
738 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
739 * This is the case also of FDDI, where the RFC 1390 says that
740 * FDDI devices should accept ARP hardware of (1) Ethernet,
741 * however, to be more robust, we'll accept both 1 (Ethernet)
742 * or 6 (IEEE 802.2)
743 */
744 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
745 arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
746 arp->ar_pro != htons(ETH_P_IP))
747 goto out_free_skb;
748 break;
749 case ARPHRD_AX25:
750 if (arp->ar_pro != htons(AX25_P_IP) ||
751 arp->ar_hrd != htons(ARPHRD_AX25))
752 goto out_free_skb;
753 break;
754 case ARPHRD_NETROM:
755 if (arp->ar_pro != htons(AX25_P_IP) ||
756 arp->ar_hrd != htons(ARPHRD_NETROM))
757 goto out_free_skb;
758 break;
759 }
760
761 /* Understand only these message types */
762
763 if (arp->ar_op != htons(ARPOP_REPLY) &&
764 arp->ar_op != htons(ARPOP_REQUEST))
765 goto out_free_skb;
766
767/*
768 * Extract fields
769 */
770 arp_ptr = (unsigned char *)(arp + 1);
771 sha = arp_ptr;
772 arp_ptr += dev->addr_len;
773 memcpy(&sip, arp_ptr, 4);
774 arp_ptr += 4;
775 switch (dev_type) {
776#if IS_ENABLED(CONFIG_FIREWIRE_NET)
777 case ARPHRD_IEEE1394:
778 break;
779#endif
780 default:
781 tha = arp_ptr;
782 arp_ptr += dev->addr_len;
783 }
784 memcpy(&tip, arp_ptr, 4);
785/*
786 * Check for bad requests for 127.x.x.x and requests for multicast
787 * addresses. If this is one such, delete it.
788 */
789 if (ipv4_is_multicast(tip) ||
790 (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip)))
791 goto out_free_skb;
792
793 /*
794 * For some 802.11 wireless deployments (and possibly other networks),
795 * there will be an ARP proxy and gratuitous ARP frames are attacks
796 * and thus should not be accepted.
797 */
798 if (sip == tip && IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP))
799 goto out_free_skb;
800
801/*
802 * Special case: We must set Frame Relay source Q.922 address
803 */
804 if (dev_type == ARPHRD_DLCI)
805 sha = dev->broadcast;
806
807/*
808 * Process entry. The idea here is we want to send a reply if it is a
809 * request for us or if it is a request for someone else that we hold
810 * a proxy for. We want to add an entry to our cache if it is a reply
811 * to us or if it is a request for our address.
812 * (The assumption for this last is that if someone is requesting our
813 * address, they are probably intending to talk to us, so it saves time
814 * if we cache their address. Their address is also probably not in
815 * our cache, since ours is not in their cache.)
816 *
817 * Putting this another way, we only care about replies if they are to
818 * us, in which case we add them to the cache. For requests, we care
819 * about those for us and those for our proxies. We reply to both,
820 * and in the case of requests for us we add the requester to the arp
821 * cache.
822 */
823
824 if (arp->ar_op == htons(ARPOP_REQUEST) && skb_metadata_dst(skb))
825 reply_dst = (struct dst_entry *)
826 iptunnel_metadata_reply(skb_metadata_dst(skb),
827 GFP_ATOMIC);
828
829 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
830 if (sip == 0) {
831 if (arp->ar_op == htons(ARPOP_REQUEST) &&
832 inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL &&
833 !arp_ignore(in_dev, sip, tip))
834 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip,
835 sha, dev->dev_addr, sha, reply_dst);
836 goto out_consume_skb;
837 }
838
839 if (arp->ar_op == htons(ARPOP_REQUEST) &&
840 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
841
842 rt = skb_rtable(skb);
843 addr_type = rt->rt_type;
844
845 if (addr_type == RTN_LOCAL) {
846 int dont_send;
847
848 dont_send = arp_ignore(in_dev, sip, tip);
849 if (!dont_send && IN_DEV_ARPFILTER(in_dev))
850 dont_send = arp_filter(sip, tip, dev);
851 if (!dont_send) {
852 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
853 if (n) {
854 arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
855 sip, dev, tip, sha,
856 dev->dev_addr, sha,
857 reply_dst);
858 neigh_release(n);
859 }
860 }
861 goto out_consume_skb;
862 } else if (IN_DEV_FORWARD(in_dev)) {
863 if (addr_type == RTN_UNICAST &&
864 (arp_fwd_proxy(in_dev, dev, rt) ||
865 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
866 (rt->dst.dev != dev &&
867 pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
868 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
869 if (n)
870 neigh_release(n);
871
872 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
873 skb->pkt_type == PACKET_HOST ||
874 NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) {
875 arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
876 sip, dev, tip, sha,
877 dev->dev_addr, sha,
878 reply_dst);
879 } else {
880 pneigh_enqueue(&arp_tbl,
881 in_dev->arp_parms, skb);
882 goto out_free_dst;
883 }
884 goto out_consume_skb;
885 }
886 }
887 }
888
889 /* Update our ARP tables */
890
891 n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
892
893 addr_type = -1;
894 if (n || arp_accept(in_dev, sip)) {
895 is_garp = arp_is_garp(net, dev, &addr_type, arp->ar_op,
896 sip, tip, sha, tha);
897 }
898
899 if (arp_accept(in_dev, sip)) {
900 /* Unsolicited ARP is not accepted by default.
901 It is possible, that this option should be enabled for some
902 devices (strip is candidate)
903 */
904 if (!n &&
905 (is_garp ||
906 (arp->ar_op == htons(ARPOP_REPLY) &&
907 (addr_type == RTN_UNICAST ||
908 (addr_type < 0 &&
909 /* postpone calculation to as late as possible */
910 inet_addr_type_dev_table(net, dev, sip) ==
911 RTN_UNICAST)))))
912 n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
913 }
914
915 if (n) {
916 int state = NUD_REACHABLE;
917 int override;
918
919 /* If several different ARP replies follows back-to-back,
920 use the FIRST one. It is possible, if several proxy
921 agents are active. Taking the first reply prevents
922 arp trashing and chooses the fastest router.
923 */
924 override = time_after(jiffies,
925 n->updated +
926 NEIGH_VAR(n->parms, LOCKTIME)) ||
927 is_garp;
928
929 /* Broadcast replies and request packets
930 do not assert neighbour reachability.
931 */
932 if (arp->ar_op != htons(ARPOP_REPLY) ||
933 skb->pkt_type != PACKET_HOST)
934 state = NUD_STALE;
935 neigh_update(n, sha, state,
936 override ? NEIGH_UPDATE_F_OVERRIDE : 0, 0);
937 neigh_release(n);
938 }
939
940out_consume_skb:
941 consume_skb(skb);
942
943out_free_dst:
944 dst_release(reply_dst);
945 return NET_RX_SUCCESS;
946
947out_free_skb:
948 kfree_skb(skb);
949 return NET_RX_DROP;
950}
951
952static void parp_redo(struct sk_buff *skb)
953{
954 arp_process(dev_net(skb->dev), NULL, skb);
955}
956
957static int arp_is_multicast(const void *pkey)
958{
959 return ipv4_is_multicast(*((__be32 *)pkey));
960}
961
962/*
963 * Receive an arp request from the device layer.
964 */
965
966static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
967 struct packet_type *pt, struct net_device *orig_dev)
968{
969 const struct arphdr *arp;
970
971 /* do not tweak dropwatch on an ARP we will ignore */
972 if (dev->flags & IFF_NOARP ||
973 skb->pkt_type == PACKET_OTHERHOST ||
974 skb->pkt_type == PACKET_LOOPBACK)
975 goto consumeskb;
976
977 skb = skb_share_check(skb, GFP_ATOMIC);
978 if (!skb)
979 goto out_of_mem;
980
981 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
982 if (!pskb_may_pull(skb, arp_hdr_len(dev)))
983 goto freeskb;
984
985 arp = arp_hdr(skb);
986 if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4)
987 goto freeskb;
988
989 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
990
991 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN,
992 dev_net(dev), NULL, skb, dev, NULL,
993 arp_process);
994
995consumeskb:
996 consume_skb(skb);
997 return NET_RX_SUCCESS;
998freeskb:
999 kfree_skb(skb);
1000out_of_mem:
1001 return NET_RX_DROP;
1002}
1003
1004/*
1005 * User level interface (ioctl)
1006 */
1007
1008static struct net_device *arp_req_dev_by_name(struct net *net, struct arpreq *r,
1009 bool getarp)
1010{
1011 struct net_device *dev;
1012
1013 if (getarp)
1014 dev = dev_get_by_name_rcu(net, r->arp_dev);
1015 else
1016 dev = __dev_get_by_name(net, r->arp_dev);
1017 if (!dev)
1018 return ERR_PTR(-ENODEV);
1019
1020 /* Mmmm... It is wrong... ARPHRD_NETROM == 0 */
1021 if (!r->arp_ha.sa_family)
1022 r->arp_ha.sa_family = dev->type;
1023
1024 if ((r->arp_flags & ATF_COM) && r->arp_ha.sa_family != dev->type)
1025 return ERR_PTR(-EINVAL);
1026
1027 return dev;
1028}
1029
1030static struct net_device *arp_req_dev(struct net *net, struct arpreq *r)
1031{
1032 struct net_device *dev;
1033 struct rtable *rt;
1034 __be32 ip;
1035
1036 if (r->arp_dev[0])
1037 return arp_req_dev_by_name(net, r, false);
1038
1039 if (r->arp_flags & ATF_PUBL)
1040 return NULL;
1041
1042 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1043
1044 rt = ip_route_output(net, ip, 0, 0, 0, RT_SCOPE_LINK);
1045 if (IS_ERR(rt))
1046 return ERR_CAST(rt);
1047
1048 dev = rt->dst.dev;
1049 ip_rt_put(rt);
1050
1051 if (!dev)
1052 return ERR_PTR(-EINVAL);
1053
1054 return dev;
1055}
1056
1057/*
1058 * Set (create) an ARP cache entry.
1059 */
1060
1061static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
1062{
1063 if (!dev) {
1064 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
1065 return 0;
1066 }
1067 if (__in_dev_get_rtnl(dev)) {
1068 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
1069 return 0;
1070 }
1071 return -ENXIO;
1072}
1073
1074static int arp_req_set_public(struct net *net, struct arpreq *r,
1075 struct net_device *dev)
1076{
1077 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1078
1079 if (!dev && (r->arp_flags & ATF_COM)) {
1080 dev = dev_getbyhwaddr(net, r->arp_ha.sa_family,
1081 r->arp_ha.sa_data);
1082 if (!dev)
1083 return -ENODEV;
1084 }
1085 if (mask) {
1086 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1087
1088 if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1))
1089 return -ENOBUFS;
1090 return 0;
1091 }
1092
1093 return arp_req_set_proxy(net, dev, 1);
1094}
1095
1096static int arp_req_set(struct net *net, struct arpreq *r)
1097{
1098 struct neighbour *neigh;
1099 struct net_device *dev;
1100 __be32 ip;
1101 int err;
1102
1103 dev = arp_req_dev(net, r);
1104 if (IS_ERR(dev))
1105 return PTR_ERR(dev);
1106
1107 if (r->arp_flags & ATF_PUBL)
1108 return arp_req_set_public(net, r, dev);
1109
1110 switch (dev->type) {
1111#if IS_ENABLED(CONFIG_FDDI)
1112 case ARPHRD_FDDI:
1113 /*
1114 * According to RFC 1390, FDDI devices should accept ARP
1115 * hardware types of 1 (Ethernet). However, to be more
1116 * robust, we'll accept hardware types of either 1 (Ethernet)
1117 * or 6 (IEEE 802.2).
1118 */
1119 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1120 r->arp_ha.sa_family != ARPHRD_ETHER &&
1121 r->arp_ha.sa_family != ARPHRD_IEEE802)
1122 return -EINVAL;
1123 break;
1124#endif
1125 default:
1126 if (r->arp_ha.sa_family != dev->type)
1127 return -EINVAL;
1128 break;
1129 }
1130
1131 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1132
1133 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1134 err = PTR_ERR(neigh);
1135 if (!IS_ERR(neigh)) {
1136 unsigned int state = NUD_STALE;
1137
1138 if (r->arp_flags & ATF_PERM) {
1139 r->arp_flags |= ATF_COM;
1140 state = NUD_PERMANENT;
1141 }
1142
1143 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ?
1144 r->arp_ha.sa_data : NULL, state,
1145 NEIGH_UPDATE_F_OVERRIDE |
1146 NEIGH_UPDATE_F_ADMIN, 0);
1147 neigh_release(neigh);
1148 }
1149 return err;
1150}
1151
1152static unsigned int arp_state_to_flags(struct neighbour *neigh)
1153{
1154 if (neigh->nud_state&NUD_PERMANENT)
1155 return ATF_PERM | ATF_COM;
1156 else if (neigh->nud_state&NUD_VALID)
1157 return ATF_COM;
1158 else
1159 return 0;
1160}
1161
1162/*
1163 * Get an ARP cache entry.
1164 */
1165
1166static int arp_req_get(struct net *net, struct arpreq *r)
1167{
1168 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1169 struct neighbour *neigh;
1170 struct net_device *dev;
1171
1172 if (!r->arp_dev[0])
1173 return -ENODEV;
1174
1175 dev = arp_req_dev_by_name(net, r, true);
1176 if (IS_ERR(dev))
1177 return PTR_ERR(dev);
1178
1179 neigh = neigh_lookup(&arp_tbl, &ip, dev);
1180 if (!neigh)
1181 return -ENXIO;
1182
1183 if (READ_ONCE(neigh->nud_state) & NUD_NOARP) {
1184 neigh_release(neigh);
1185 return -ENXIO;
1186 }
1187
1188 read_lock_bh(&neigh->lock);
1189 memcpy(r->arp_ha.sa_data, neigh->ha,
1190 min(dev->addr_len, sizeof(r->arp_ha.sa_data_min)));
1191 r->arp_flags = arp_state_to_flags(neigh);
1192 read_unlock_bh(&neigh->lock);
1193
1194 neigh_release(neigh);
1195
1196 r->arp_ha.sa_family = dev->type;
1197 netdev_copy_name(dev, r->arp_dev);
1198
1199 return 0;
1200}
1201
1202int arp_invalidate(struct net_device *dev, __be32 ip, bool force)
1203{
1204 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
1205 int err = -ENXIO;
1206 struct neigh_table *tbl = &arp_tbl;
1207
1208 if (neigh) {
1209 if ((READ_ONCE(neigh->nud_state) & NUD_VALID) && !force) {
1210 neigh_release(neigh);
1211 return 0;
1212 }
1213
1214 if (READ_ONCE(neigh->nud_state) & ~NUD_NOARP)
1215 err = neigh_update(neigh, NULL, NUD_FAILED,
1216 NEIGH_UPDATE_F_OVERRIDE|
1217 NEIGH_UPDATE_F_ADMIN, 0);
1218 write_lock_bh(&tbl->lock);
1219 neigh_release(neigh);
1220 neigh_remove_one(neigh);
1221 write_unlock_bh(&tbl->lock);
1222 }
1223
1224 return err;
1225}
1226
1227static int arp_req_delete_public(struct net *net, struct arpreq *r,
1228 struct net_device *dev)
1229{
1230 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1231
1232 if (mask) {
1233 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1234
1235 return pneigh_delete(&arp_tbl, net, &ip, dev);
1236 }
1237
1238 return arp_req_set_proxy(net, dev, 0);
1239}
1240
1241static int arp_req_delete(struct net *net, struct arpreq *r)
1242{
1243 struct net_device *dev;
1244 __be32 ip;
1245
1246 dev = arp_req_dev(net, r);
1247 if (IS_ERR(dev))
1248 return PTR_ERR(dev);
1249
1250 if (r->arp_flags & ATF_PUBL)
1251 return arp_req_delete_public(net, r, dev);
1252
1253 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1254
1255 return arp_invalidate(dev, ip, true);
1256}
1257
1258/*
1259 * Handle an ARP layer I/O control request.
1260 */
1261
1262int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1263{
1264 struct arpreq r;
1265 __be32 *netmask;
1266 int err;
1267
1268 switch (cmd) {
1269 case SIOCDARP:
1270 case SIOCSARP:
1271 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1272 return -EPERM;
1273 fallthrough;
1274 case SIOCGARP:
1275 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1276 if (err)
1277 return -EFAULT;
1278 break;
1279 default:
1280 return -EINVAL;
1281 }
1282
1283 if (r.arp_pa.sa_family != AF_INET)
1284 return -EPFNOSUPPORT;
1285
1286 if (!(r.arp_flags & ATF_PUBL) &&
1287 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1288 return -EINVAL;
1289
1290 netmask = &((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr;
1291 if (!(r.arp_flags & ATF_NETMASK))
1292 *netmask = htonl(0xFFFFFFFFUL);
1293 else if (*netmask && *netmask != htonl(0xFFFFFFFFUL))
1294 return -EINVAL;
1295
1296 switch (cmd) {
1297 case SIOCDARP:
1298 rtnl_lock();
1299 err = arp_req_delete(net, &r);
1300 rtnl_unlock();
1301 break;
1302 case SIOCSARP:
1303 rtnl_lock();
1304 err = arp_req_set(net, &r);
1305 rtnl_unlock();
1306 break;
1307 case SIOCGARP:
1308 rcu_read_lock();
1309 err = arp_req_get(net, &r);
1310 rcu_read_unlock();
1311
1312 if (!err && copy_to_user(arg, &r, sizeof(r)))
1313 err = -EFAULT;
1314 break;
1315 }
1316
1317 return err;
1318}
1319
1320static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1321 void *ptr)
1322{
1323 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
1324 struct netdev_notifier_change_info *change_info;
1325 struct in_device *in_dev;
1326 bool evict_nocarrier;
1327
1328 switch (event) {
1329 case NETDEV_CHANGEADDR:
1330 neigh_changeaddr(&arp_tbl, dev);
1331 rt_cache_flush(dev_net(dev));
1332 break;
1333 case NETDEV_CHANGE:
1334 change_info = ptr;
1335 if (change_info->flags_changed & IFF_NOARP)
1336 neigh_changeaddr(&arp_tbl, dev);
1337
1338 in_dev = __in_dev_get_rtnl(dev);
1339 if (!in_dev)
1340 evict_nocarrier = true;
1341 else
1342 evict_nocarrier = IN_DEV_ARP_EVICT_NOCARRIER(in_dev);
1343
1344 if (evict_nocarrier && !netif_carrier_ok(dev))
1345 neigh_carrier_down(&arp_tbl, dev);
1346 break;
1347 default:
1348 break;
1349 }
1350
1351 return NOTIFY_DONE;
1352}
1353
1354static struct notifier_block arp_netdev_notifier = {
1355 .notifier_call = arp_netdev_event,
1356};
1357
1358/* Note, that it is not on notifier chain.
1359 It is necessary, that this routine was called after route cache will be
1360 flushed.
1361 */
1362void arp_ifdown(struct net_device *dev)
1363{
1364 neigh_ifdown(&arp_tbl, dev);
1365}
1366
1367
1368/*
1369 * Called once on startup.
1370 */
1371
1372static struct packet_type arp_packet_type __read_mostly = {
1373 .type = cpu_to_be16(ETH_P_ARP),
1374 .func = arp_rcv,
1375};
1376
1377#ifdef CONFIG_PROC_FS
1378#if IS_ENABLED(CONFIG_AX25)
1379
1380/*
1381 * ax25 -> ASCII conversion
1382 */
1383static void ax2asc2(ax25_address *a, char *buf)
1384{
1385 char c, *s;
1386 int n;
1387
1388 for (n = 0, s = buf; n < 6; n++) {
1389 c = (a->ax25_call[n] >> 1) & 0x7F;
1390
1391 if (c != ' ')
1392 *s++ = c;
1393 }
1394
1395 *s++ = '-';
1396 n = (a->ax25_call[6] >> 1) & 0x0F;
1397 if (n > 9) {
1398 *s++ = '1';
1399 n -= 10;
1400 }
1401
1402 *s++ = n + '0';
1403 *s++ = '\0';
1404
1405 if (*buf == '\0' || *buf == '-') {
1406 buf[0] = '*';
1407 buf[1] = '\0';
1408 }
1409}
1410#endif /* CONFIG_AX25 */
1411
1412#define HBUFFERLEN 30
1413
1414static void arp_format_neigh_entry(struct seq_file *seq,
1415 struct neighbour *n)
1416{
1417 char hbuffer[HBUFFERLEN];
1418 int k, j;
1419 char tbuf[16];
1420 struct net_device *dev = n->dev;
1421 int hatype = dev->type;
1422
1423 read_lock(&n->lock);
1424 /* Convert hardware address to XX:XX:XX:XX ... form. */
1425#if IS_ENABLED(CONFIG_AX25)
1426 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1427 ax2asc2((ax25_address *)n->ha, hbuffer);
1428 else {
1429#endif
1430 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1431 hbuffer[k++] = hex_asc_hi(n->ha[j]);
1432 hbuffer[k++] = hex_asc_lo(n->ha[j]);
1433 hbuffer[k++] = ':';
1434 }
1435 if (k != 0)
1436 --k;
1437 hbuffer[k] = 0;
1438#if IS_ENABLED(CONFIG_AX25)
1439 }
1440#endif
1441 sprintf(tbuf, "%pI4", n->primary_key);
1442 seq_printf(seq, "%-16s 0x%-10x0x%-10x%-17s * %s\n",
1443 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1444 read_unlock(&n->lock);
1445}
1446
1447static void arp_format_pneigh_entry(struct seq_file *seq,
1448 struct pneigh_entry *n)
1449{
1450 struct net_device *dev = n->dev;
1451 int hatype = dev ? dev->type : 0;
1452 char tbuf[16];
1453
1454 sprintf(tbuf, "%pI4", n->key);
1455 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1456 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1457 dev ? dev->name : "*");
1458}
1459
1460static int arp_seq_show(struct seq_file *seq, void *v)
1461{
1462 if (v == SEQ_START_TOKEN) {
1463 seq_puts(seq, "IP address HW type Flags "
1464 "HW address Mask Device\n");
1465 } else {
1466 struct neigh_seq_state *state = seq->private;
1467
1468 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1469 arp_format_pneigh_entry(seq, v);
1470 else
1471 arp_format_neigh_entry(seq, v);
1472 }
1473
1474 return 0;
1475}
1476
1477static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1478{
1479 /* Don't want to confuse "arp -a" w/ magic entries,
1480 * so we tell the generic iterator to skip NUD_NOARP.
1481 */
1482 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1483}
1484
1485static const struct seq_operations arp_seq_ops = {
1486 .start = arp_seq_start,
1487 .next = neigh_seq_next,
1488 .stop = neigh_seq_stop,
1489 .show = arp_seq_show,
1490};
1491#endif /* CONFIG_PROC_FS */
1492
1493static int __net_init arp_net_init(struct net *net)
1494{
1495 if (!proc_create_net("arp", 0444, net->proc_net, &arp_seq_ops,
1496 sizeof(struct neigh_seq_state)))
1497 return -ENOMEM;
1498 return 0;
1499}
1500
1501static void __net_exit arp_net_exit(struct net *net)
1502{
1503 remove_proc_entry("arp", net->proc_net);
1504}
1505
1506static struct pernet_operations arp_net_ops = {
1507 .init = arp_net_init,
1508 .exit = arp_net_exit,
1509};
1510
1511void __init arp_init(void)
1512{
1513 neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl);
1514
1515 dev_add_pack(&arp_packet_type);
1516 register_pernet_subsys(&arp_net_ops);
1517#ifdef CONFIG_SYSCTL
1518 neigh_sysctl_register(NULL, &arp_tbl.parms, NULL);
1519#endif
1520 register_netdevice_notifier(&arp_netdev_notifier);
1521}