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