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_DEFAULT,
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(naddr: addr, buf: haddr);
194 return 0;
195 case ARPHRD_INFINIBAND:
196 ip_ib_mc_map(naddr: addr, broadcast: dev->broadcast, buf: haddr);
197 return 0;
198 case ARPHRD_IPGRE:
199 ip_ipgre_mc_map(naddr: addr, broadcast: dev->broadcast, buf: haddr);
200 return 0;
201 default:
202 if (dir) {
203 memcpy(to: haddr, from: dev->broadcast, len: 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(n: 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(to: neigh->primary_key, from: &inaddr_any, len: 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(net: dev_net(dev), dev, addr);
243
244 parms = in_dev->arp_parms;
245 __neigh_parms_put(parms: 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, haddr: neigh->ha, dev, dir: 1);
272 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) {
273 neigh->nud_state = NUD_NOARP;
274 memcpy(to: neigh->ha, from: dev->dev_addr, len: dev->addr_len);
275 } else if (neigh->type == RTN_BROADCAST ||
276 (dev->flags & IFF_POINTOPOINT)) {
277 neigh->nud_state = NUD_NOARP;
278 memcpy(to: neigh->ha, from: dev->broadcast, len: 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, reason: 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: 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(v: &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(net: dev_net(dev), dev,
353 addr: 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(net: dev_net(dev), dev,
361 addr: saddr) == RTN_LOCAL) {
362 /* saddr should be known to target */
363 if (inet_addr_onlink(in_dev, a: target, b: 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, dst: target, scope: 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: dst_ha, n: 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(n: 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, dest_ip: target, dev, src_ip: saddr,
393 dest_hw: dst_hw, src_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(dev: 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, dst: sip, local: tip, scope);
430}
431
432static int arp_accept(struct in_device *in_dev, __be32 sip)
433{
434 struct net *net = dev_net(dev: 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, dst: sip, local: 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, daddr: sip, saddr: tip, dscp: 0, oif: l3mdev_master_ifindex_rcu(dev),
460 scope: RT_SCOPE_UNIVERSE);
461 if (IS_ERR(ptr: 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(dev: 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(size: arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
562 if (!skb)
563 return NULL;
564
565 skb_reserve(skb, len: hlen);
566 skb_reset_network_header(skb);
567 arp = skb_put(skb, len: 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, type: ptype, daddr: dest_hw, saddr: src_hw, len: 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(to: arp_ptr, from: src_hw, len: dev->addr_len);
626 arp_ptr += dev->addr_len;
627 memcpy(to: arp_ptr, from: &src_ip, len: 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(to: arp_ptr, from: target_hw, len: dev->addr_len);
638 else
639 memset(s: arp_ptr, c: 0, n: dev->addr_len);
640 arp_ptr += dev->addr_len;
641 }
642 memcpy(to: arp_ptr, from: &dest_ip, len: 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(pf: NFPROTO_ARP, NF_ARP_OUT,
665 net: dev_net_rcu(dev: skb->dev), NULL, skb, NULL, out: skb->dev,
666 okfn: 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, addr: 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(to: &sip, from: arp_ptr, len: 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(to: &tip, from: arp_ptr, len: 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(addr: tip) ||
790 (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(addr: 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(md: 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, addr: tip) == RTN_LOCAL &&
833 !arp_ignore(in_dev, sip, tip))
834 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, dest_ip: sip, dev, src_ip: tip,
835 dest_hw: sha, src_hw: dev->dev_addr, target_hw: sha, dst: reply_dst);
836 goto out_consume_skb;
837 }
838
839 if (arp->ar_op == htons(ARPOP_REQUEST) &&
840 ip_route_input_noref(skb, daddr: tip, saddr: sip, dscp: 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(tbl: &arp_tbl, lladdr: sha, saddr: &sip, dev);
853 if (n) {
854 arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
855 dest_ip: sip, dev, src_ip: tip, dest_hw: sha,
856 src_hw: dev->dev_addr, target_hw: sha,
857 dst: reply_dst);
858 neigh_release(neigh: 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(tbl: &arp_tbl, net, key: &tip, dev)))) {
868 n = neigh_event_ns(tbl: &arp_tbl, lladdr: sha, saddr: &sip, dev);
869 if (n)
870 neigh_release(neigh: 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 dest_ip: sip, dev, src_ip: tip, dest_hw: sha,
877 src_hw: dev->dev_addr, target_hw: sha,
878 dst: reply_dst);
879 } else {
880 pneigh_enqueue(tbl: &arp_tbl,
881 p: 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(tbl: &arp_tbl, pkey: &sip, dev, creat: 0);
892
893 addr_type = -1;
894 if (n || arp_accept(in_dev, sip)) {
895 is_garp = arp_is_garp(net, dev, addr_type: &addr_type, ar_op: 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, addr: sip) ==
911 RTN_UNICAST)))))
912 n = __neigh_lookup(tbl: &arp_tbl, pkey: &sip, dev, creat: 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(neigh: n, lladdr: sha, new: state,
936 flags: override ? NEIGH_UPDATE_F_OVERRIDE : 0, nlmsg_pid: 0);
937 neigh_release(neigh: n);
938 }
939
940out_consume_skb:
941 consume_skb(skb);
942
943out_free_dst:
944 dst_release(dst: 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(net: dev_net(dev: skb->dev), NULL, skb);
955}
956
957static int arp_is_multicast(const void *pkey)
958{
959 return ipv4_is_multicast(addr: *((__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 enum skb_drop_reason drop_reason;
970 const struct arphdr *arp;
971
972 /* do not tweak dropwatch on an ARP we will ignore */
973 if (dev->flags & IFF_NOARP ||
974 skb->pkt_type == PACKET_OTHERHOST ||
975 skb->pkt_type == PACKET_LOOPBACK)
976 goto consumeskb;
977
978 skb = skb_share_check(skb, GFP_ATOMIC);
979 if (!skb)
980 goto out_of_mem;
981
982 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
983 drop_reason = pskb_may_pull_reason(skb, len: arp_hdr_len(dev));
984 if (drop_reason != SKB_NOT_DROPPED_YET)
985 goto freeskb;
986
987 arp = arp_hdr(skb);
988 if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4) {
989 drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
990 goto freeskb;
991 }
992
993 memset(NEIGH_CB(skb), c: 0, n: sizeof(struct neighbour_cb));
994
995 return NF_HOOK(pf: NFPROTO_ARP, NF_ARP_IN,
996 net: dev_net(dev), NULL, skb, in: dev, NULL,
997 okfn: arp_process);
998
999consumeskb:
1000 consume_skb(skb);
1001 return NET_RX_SUCCESS;
1002freeskb:
1003 kfree_skb_reason(skb, reason: drop_reason);
1004out_of_mem:
1005 return NET_RX_DROP;
1006}
1007
1008/*
1009 * User level interface (ioctl)
1010 */
1011
1012static struct net_device *arp_req_dev_by_name(struct net *net, struct arpreq *r,
1013 bool getarp)
1014{
1015 struct net_device *dev;
1016
1017 if (getarp)
1018 dev = dev_get_by_name_rcu(net, name: r->arp_dev);
1019 else
1020 dev = __dev_get_by_name(net, name: r->arp_dev);
1021 if (!dev)
1022 return ERR_PTR(error: -ENODEV);
1023
1024 /* Mmmm... It is wrong... ARPHRD_NETROM == 0 */
1025 if (!r->arp_ha.sa_family)
1026 r->arp_ha.sa_family = dev->type;
1027
1028 if ((r->arp_flags & ATF_COM) && r->arp_ha.sa_family != dev->type)
1029 return ERR_PTR(error: -EINVAL);
1030
1031 return dev;
1032}
1033
1034static struct net_device *arp_req_dev(struct net *net, struct arpreq *r)
1035{
1036 struct net_device *dev;
1037 struct rtable *rt;
1038 __be32 ip;
1039
1040 if (r->arp_dev[0])
1041 return arp_req_dev_by_name(net, r, getarp: false);
1042
1043 if (r->arp_flags & ATF_PUBL)
1044 return NULL;
1045
1046 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1047
1048 rt = ip_route_output(net, daddr: ip, saddr: 0, dscp: 0, oif: 0, scope: RT_SCOPE_LINK);
1049 if (IS_ERR(ptr: rt))
1050 return ERR_CAST(ptr: rt);
1051
1052 dev = rt->dst.dev;
1053 ip_rt_put(rt);
1054
1055 if (!dev)
1056 return ERR_PTR(error: -EINVAL);
1057
1058 return dev;
1059}
1060
1061/*
1062 * Set (create) an ARP cache entry.
1063 */
1064
1065static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
1066{
1067 if (!dev) {
1068 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
1069 return 0;
1070 }
1071 if (__in_dev_get_rtnl_net(dev)) {
1072 IN_DEV_CONF_SET(__in_dev_get_rtnl_net(dev), PROXY_ARP, on);
1073 return 0;
1074 }
1075 return -ENXIO;
1076}
1077
1078static int arp_req_set_public(struct net *net, struct arpreq *r,
1079 struct net_device *dev)
1080{
1081 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1082
1083 if (!dev && (r->arp_flags & ATF_COM)) {
1084 dev = dev_getbyhwaddr(net, type: r->arp_ha.sa_family,
1085 hwaddr: r->arp_ha.sa_data);
1086 if (!dev)
1087 return -ENODEV;
1088 }
1089 if (mask) {
1090 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1091
1092 return pneigh_create(tbl: &arp_tbl, net, key: &ip, dev, flags: 0, protocol: 0, permanent: false);
1093 }
1094
1095 return arp_req_set_proxy(net, dev, on: 1);
1096}
1097
1098static int arp_req_set(struct net *net, struct arpreq *r)
1099{
1100 struct neighbour *neigh;
1101 struct net_device *dev;
1102 __be32 ip;
1103 int err;
1104
1105 dev = arp_req_dev(net, r);
1106 if (IS_ERR(ptr: dev))
1107 return PTR_ERR(ptr: dev);
1108
1109 if (r->arp_flags & ATF_PUBL)
1110 return arp_req_set_public(net, r, dev);
1111
1112 switch (dev->type) {
1113#if IS_ENABLED(CONFIG_FDDI)
1114 case ARPHRD_FDDI:
1115 /*
1116 * According to RFC 1390, FDDI devices should accept ARP
1117 * hardware types of 1 (Ethernet). However, to be more
1118 * robust, we'll accept hardware types of either 1 (Ethernet)
1119 * or 6 (IEEE 802.2).
1120 */
1121 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1122 r->arp_ha.sa_family != ARPHRD_ETHER &&
1123 r->arp_ha.sa_family != ARPHRD_IEEE802)
1124 return -EINVAL;
1125 break;
1126#endif
1127 default:
1128 if (r->arp_ha.sa_family != dev->type)
1129 return -EINVAL;
1130 break;
1131 }
1132
1133 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1134
1135 neigh = __neigh_lookup_errno(tbl: &arp_tbl, pkey: &ip, dev);
1136 err = PTR_ERR(ptr: neigh);
1137 if (!IS_ERR(ptr: neigh)) {
1138 unsigned int state = NUD_STALE;
1139
1140 if (r->arp_flags & ATF_PERM) {
1141 r->arp_flags |= ATF_COM;
1142 state = NUD_PERMANENT;
1143 }
1144
1145 err = neigh_update(neigh, lladdr: (r->arp_flags & ATF_COM) ?
1146 r->arp_ha.sa_data : NULL, new: state,
1147 NEIGH_UPDATE_F_OVERRIDE |
1148 NEIGH_UPDATE_F_ADMIN, nlmsg_pid: 0);
1149 neigh_release(neigh);
1150 }
1151 return err;
1152}
1153
1154static unsigned int arp_state_to_flags(struct neighbour *neigh)
1155{
1156 if (neigh->nud_state&NUD_PERMANENT)
1157 return ATF_PERM | ATF_COM;
1158 else if (neigh->nud_state&NUD_VALID)
1159 return ATF_COM;
1160 else
1161 return 0;
1162}
1163
1164/*
1165 * Get an ARP cache entry.
1166 */
1167
1168static int arp_req_get(struct net *net, struct arpreq *r)
1169{
1170 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1171 struct neighbour *neigh;
1172 struct net_device *dev;
1173
1174 if (!r->arp_dev[0])
1175 return -ENODEV;
1176
1177 dev = arp_req_dev_by_name(net, r, getarp: true);
1178 if (IS_ERR(ptr: dev))
1179 return PTR_ERR(ptr: dev);
1180
1181 neigh = neigh_lookup(tbl: &arp_tbl, pkey: &ip, dev);
1182 if (!neigh)
1183 return -ENXIO;
1184
1185 if (READ_ONCE(neigh->nud_state) & NUD_NOARP) {
1186 neigh_release(neigh);
1187 return -ENXIO;
1188 }
1189
1190 read_lock_bh(&neigh->lock);
1191 memcpy(to: r->arp_ha.sa_data, from: neigh->ha,
1192 min(dev->addr_len, sizeof(r->arp_ha.sa_data_min)));
1193 r->arp_flags = arp_state_to_flags(neigh);
1194 read_unlock_bh(&neigh->lock);
1195
1196 neigh_release(neigh);
1197
1198 r->arp_ha.sa_family = dev->type;
1199 netdev_copy_name(dev, name: r->arp_dev);
1200
1201 return 0;
1202}
1203
1204int arp_invalidate(struct net_device *dev, __be32 ip, bool force)
1205{
1206 struct neighbour *neigh = neigh_lookup(tbl: &arp_tbl, pkey: &ip, dev);
1207 int err = -ENXIO;
1208 struct neigh_table *tbl = &arp_tbl;
1209
1210 if (neigh) {
1211 if ((READ_ONCE(neigh->nud_state) & NUD_VALID) && !force) {
1212 neigh_release(neigh);
1213 return 0;
1214 }
1215
1216 if (READ_ONCE(neigh->nud_state) & ~NUD_NOARP)
1217 err = neigh_update(neigh, NULL, NUD_FAILED,
1218 NEIGH_UPDATE_F_OVERRIDE|
1219 NEIGH_UPDATE_F_ADMIN, nlmsg_pid: 0);
1220 write_lock_bh(&tbl->lock);
1221 neigh_release(neigh);
1222 neigh_remove_one(ndel: neigh);
1223 write_unlock_bh(&tbl->lock);
1224 }
1225
1226 return err;
1227}
1228
1229static int arp_req_delete_public(struct net *net, struct arpreq *r,
1230 struct net_device *dev)
1231{
1232 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1233
1234 if (mask) {
1235 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1236
1237 return pneigh_delete(tbl: &arp_tbl, net, key: &ip, dev);
1238 }
1239
1240 return arp_req_set_proxy(net, dev, on: 0);
1241}
1242
1243static int arp_req_delete(struct net *net, struct arpreq *r)
1244{
1245 struct net_device *dev;
1246 __be32 ip;
1247
1248 dev = arp_req_dev(net, r);
1249 if (IS_ERR(ptr: dev))
1250 return PTR_ERR(ptr: dev);
1251
1252 if (r->arp_flags & ATF_PUBL)
1253 return arp_req_delete_public(net, r, dev);
1254
1255 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1256
1257 return arp_invalidate(dev, ip, force: true);
1258}
1259
1260/*
1261 * Handle an ARP layer I/O control request.
1262 */
1263
1264int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1265{
1266 struct arpreq r;
1267 __be32 *netmask;
1268 int err;
1269
1270 switch (cmd) {
1271 case SIOCDARP:
1272 case SIOCSARP:
1273 if (!ns_capable(ns: net->user_ns, CAP_NET_ADMIN))
1274 return -EPERM;
1275 fallthrough;
1276 case SIOCGARP:
1277 err = copy_from_user(to: &r, from: arg, n: sizeof(struct arpreq));
1278 if (err)
1279 return -EFAULT;
1280 break;
1281 default:
1282 return -EINVAL;
1283 }
1284
1285 if (r.arp_pa.sa_family != AF_INET)
1286 return -EPFNOSUPPORT;
1287
1288 if (!(r.arp_flags & ATF_PUBL) &&
1289 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1290 return -EINVAL;
1291
1292 netmask = &((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr;
1293 if (!(r.arp_flags & ATF_NETMASK))
1294 *netmask = htonl(0xFFFFFFFFUL);
1295 else if (*netmask && *netmask != htonl(0xFFFFFFFFUL))
1296 return -EINVAL;
1297
1298 switch (cmd) {
1299 case SIOCDARP:
1300 rtnl_net_lock(net);
1301 err = arp_req_delete(net, r: &r);
1302 rtnl_net_unlock(net);
1303 break;
1304 case SIOCSARP:
1305 rtnl_net_lock(net);
1306 err = arp_req_set(net, r: &r);
1307 rtnl_net_unlock(net);
1308 break;
1309 case SIOCGARP:
1310 rcu_read_lock();
1311 err = arp_req_get(net, r: &r);
1312 rcu_read_unlock();
1313
1314 if (!err && copy_to_user(to: arg, from: &r, n: sizeof(r)))
1315 err = -EFAULT;
1316 break;
1317 }
1318
1319 return err;
1320}
1321
1322static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1323 void *ptr)
1324{
1325 struct net_device *dev = netdev_notifier_info_to_dev(info: ptr);
1326 struct netdev_notifier_change_info *change_info;
1327 struct in_device *in_dev;
1328 bool evict_nocarrier;
1329
1330 switch (event) {
1331 case NETDEV_CHANGEADDR:
1332 neigh_changeaddr(tbl: &arp_tbl, dev);
1333 rt_cache_flush(net: dev_net(dev));
1334 break;
1335 case NETDEV_CHANGE:
1336 change_info = ptr;
1337 if (change_info->flags_changed & IFF_NOARP)
1338 neigh_changeaddr(tbl: &arp_tbl, dev);
1339
1340 in_dev = __in_dev_get_rtnl(dev);
1341 if (!in_dev)
1342 evict_nocarrier = true;
1343 else
1344 evict_nocarrier = IN_DEV_ARP_EVICT_NOCARRIER(in_dev);
1345
1346 if (evict_nocarrier && !netif_carrier_ok(dev))
1347 neigh_carrier_down(tbl: &arp_tbl, dev);
1348 break;
1349 default:
1350 break;
1351 }
1352
1353 return NOTIFY_DONE;
1354}
1355
1356static struct notifier_block arp_netdev_notifier = {
1357 .notifier_call = arp_netdev_event,
1358};
1359
1360/* Note, that it is not on notifier chain.
1361 It is necessary, that this routine was called after route cache will be
1362 flushed.
1363 */
1364void arp_ifdown(struct net_device *dev)
1365{
1366 neigh_ifdown(tbl: &arp_tbl, dev);
1367}
1368
1369
1370/*
1371 * Called once on startup.
1372 */
1373
1374static struct packet_type arp_packet_type __read_mostly = {
1375 .type = cpu_to_be16(ETH_P_ARP),
1376 .func = arp_rcv,
1377};
1378
1379#ifdef CONFIG_PROC_FS
1380#if IS_ENABLED(CONFIG_AX25)
1381
1382/*
1383 * ax25 -> ASCII conversion
1384 */
1385static void ax2asc2(ax25_address *a, char *buf)
1386{
1387 char c, *s;
1388 int n;
1389
1390 for (n = 0, s = buf; n < 6; n++) {
1391 c = (a->ax25_call[n] >> 1) & 0x7F;
1392
1393 if (c != ' ')
1394 *s++ = c;
1395 }
1396
1397 *s++ = '-';
1398 n = (a->ax25_call[6] >> 1) & 0x0F;
1399 if (n > 9) {
1400 *s++ = '1';
1401 n -= 10;
1402 }
1403
1404 *s++ = n + '0';
1405 *s++ = '\0';
1406
1407 if (*buf == '\0' || *buf == '-') {
1408 buf[0] = '*';
1409 buf[1] = '\0';
1410 }
1411}
1412#endif /* CONFIG_AX25 */
1413
1414#define HBUFFERLEN 30
1415
1416static void arp_format_neigh_entry(struct seq_file *seq,
1417 struct neighbour *n)
1418{
1419 char hbuffer[HBUFFERLEN];
1420 int k, j;
1421 char tbuf[16];
1422 struct net_device *dev = n->dev;
1423 int hatype = dev->type;
1424
1425 read_lock(&n->lock);
1426 /* Convert hardware address to XX:XX:XX:XX ... form. */
1427#if IS_ENABLED(CONFIG_AX25)
1428 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1429 ax2asc2((ax25_address *)n->ha, hbuffer);
1430 else {
1431#endif
1432 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1433 hbuffer[k++] = hex_asc_hi(n->ha[j]);
1434 hbuffer[k++] = hex_asc_lo(n->ha[j]);
1435 hbuffer[k++] = ':';
1436 }
1437 if (k != 0)
1438 --k;
1439 hbuffer[k] = 0;
1440#if IS_ENABLED(CONFIG_AX25)
1441 }
1442#endif
1443 sprintf(buf: tbuf, fmt: "%pI4", n->primary_key);
1444 seq_printf(m: seq, fmt: "%-16s 0x%-10x0x%-10x%-17s * %s\n",
1445 tbuf, hatype, arp_state_to_flags(neigh: n), hbuffer, dev->name);
1446 read_unlock(&n->lock);
1447}
1448
1449static void arp_format_pneigh_entry(struct seq_file *seq,
1450 struct pneigh_entry *n)
1451{
1452 struct net_device *dev = n->dev;
1453 int hatype = dev ? dev->type : 0;
1454 char tbuf[16];
1455
1456 sprintf(buf: tbuf, fmt: "%pI4", n->key);
1457 seq_printf(m: seq, fmt: "%-16s 0x%-10x0x%-10x%s * %s\n",
1458 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1459 dev ? dev->name : "*");
1460}
1461
1462static int arp_seq_show(struct seq_file *seq, void *v)
1463{
1464 if (v == SEQ_START_TOKEN) {
1465 seq_puts(m: seq, s: "IP address HW type Flags "
1466 "HW address Mask Device\n");
1467 } else {
1468 struct neigh_seq_state *state = seq->private;
1469
1470 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1471 arp_format_pneigh_entry(seq, n: v);
1472 else
1473 arp_format_neigh_entry(seq, n: v);
1474 }
1475
1476 return 0;
1477}
1478
1479static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1480{
1481 /* Don't want to confuse "arp -a" w/ magic entries,
1482 * so we tell the generic iterator to skip NUD_NOARP.
1483 */
1484 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1485}
1486
1487static const struct seq_operations arp_seq_ops = {
1488 .start = arp_seq_start,
1489 .next = neigh_seq_next,
1490 .stop = neigh_seq_stop,
1491 .show = arp_seq_show,
1492};
1493#endif /* CONFIG_PROC_FS */
1494
1495static int __net_init arp_net_init(struct net *net)
1496{
1497 if (!proc_create_net("arp", 0444, net->proc_net, &arp_seq_ops,
1498 sizeof(struct neigh_seq_state)))
1499 return -ENOMEM;
1500 return 0;
1501}
1502
1503static void __net_exit arp_net_exit(struct net *net)
1504{
1505 remove_proc_entry("arp", net->proc_net);
1506}
1507
1508static struct pernet_operations arp_net_ops = {
1509 .init = arp_net_init,
1510 .exit = arp_net_exit,
1511};
1512
1513void __init arp_init(void)
1514{
1515 neigh_table_init(index: NEIGH_ARP_TABLE, tbl: &arp_tbl);
1516
1517 dev_add_pack(pt: &arp_packet_type);
1518 register_pernet_subsys(&arp_net_ops);
1519#ifdef CONFIG_SYSCTL
1520 neigh_sysctl_register(NULL, p: &arp_tbl.parms, NULL);
1521#endif
1522 register_netdevice_notifier(nb: &arp_netdev_notifier);
1523}
1524