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 */
122 static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd);
123 static bool arp_key_eq(const struct neighbour *n, const void *pkey);
124 static int arp_constructor(struct neighbour *neigh);
125 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
126 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
127 static void parp_redo(struct sk_buff *skb);
128 static int arp_is_multicast(const void *pkey);
129
130 static 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
138 static 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
146 static const struct neigh_ops arp_direct_ops = {
147 .family = AF_INET,
148 .output = neigh_direct_output,
149 .connected_output = neigh_direct_output,
150 };
151
152 struct 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 };
185 EXPORT_SYMBOL(arp_tbl);
186
187 int 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
211 static 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
218 static bool arp_key_eq(const struct neighbour *neigh, const void *pkey)
219 {
220 return neigh_key_eq32(neigh, pkey);
221 }
222
223 static 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
294 static 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. */
301 static 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
323 void 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 }
331 EXPORT_SYMBOL(arp_send);
332
333 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
334 {
335 __be32 saddr = 0;
336 u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL;
337 struct net_device *dev = neigh->dev;
338 __be32 target = *(__be32 *)neigh->primary_key;
339 int probes = atomic_read(&neigh->probes);
340 struct in_device *in_dev;
341 struct dst_entry *dst = NULL;
342
343 rcu_read_lock();
344 in_dev = __in_dev_get_rcu(dev);
345 if (!in_dev) {
346 rcu_read_unlock();
347 return;
348 }
349 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
350 default:
351 case 0: /* By default announce any local IP */
352 if (skb && inet_addr_type_dev_table(dev_net(dev), dev,
353 ip_hdr(skb)->saddr) == RTN_LOCAL)
354 saddr = ip_hdr(skb)->saddr;
355 break;
356 case 1: /* Restrict announcements of saddr in same subnet */
357 if (!skb)
358 break;
359 saddr = ip_hdr(skb)->saddr;
360 if (inet_addr_type_dev_table(dev_net(dev), dev,
361 saddr) == RTN_LOCAL) {
362 /* saddr should be known to target */
363 if (inet_addr_onlink(in_dev, target, saddr))
364 break;
365 }
366 saddr = 0;
367 break;
368 case 2: /* Avoid secondary IPs, get a primary/preferred one */
369 break;
370 }
371 rcu_read_unlock();
372
373 if (!saddr)
374 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
375
376 probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES);
377 if (probes < 0) {
378 if (!(READ_ONCE(neigh->nud_state) & NUD_VALID))
379 pr_debug("trying to ucast probe in NUD_INVALID\n");
380 neigh_ha_snapshot(dst_ha, neigh, dev);
381 dst_hw = dst_ha;
382 } else {
383 probes -= NEIGH_VAR(neigh->parms, APP_PROBES);
384 if (probes < 0) {
385 neigh_app_ns(neigh);
386 return;
387 }
388 }
389
390 if (skb && !(dev->priv_flags & IFF_XMIT_DST_RELEASE))
391 dst = skb_dst(skb);
392 arp_send_dst(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
393 dst_hw, dev->dev_addr, NULL, dst);
394 }
395
396 static 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
432 static 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
452 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
453 {
454 struct rtable *rt;
455 int flag = 0;
456 /*unsigned long now; */
457 struct net *net = dev_net(dev);
458
459 rt = ip_route_output(net, sip, tip, 0, l3mdev_master_ifindex_rcu(dev),
460 RT_SCOPE_UNIVERSE);
461 if (IS_ERR(rt))
462 return 1;
463 if (rt->dst.dev != dev) {
464 __NET_INC_STATS(net, LINUX_MIB_ARPFILTER);
465 flag = 1;
466 }
467 ip_rt_put(rt);
468 return flag;
469 }
470
471 /*
472 * Check if we can use proxy ARP for this path
473 */
474 static inline int arp_fwd_proxy(struct in_device *in_dev,
475 struct net_device *dev, struct rtable *rt)
476 {
477 struct in_device *out_dev;
478 int imi, omi = -1;
479
480 if (rt->dst.dev == dev)
481 return 0;
482
483 if (!IN_DEV_PROXY_ARP(in_dev))
484 return 0;
485 imi = IN_DEV_MEDIUM_ID(in_dev);
486 if (imi == 0)
487 return 1;
488 if (imi == -1)
489 return 0;
490
491 /* place to check for proxy_arp for routes */
492
493 out_dev = __in_dev_get_rcu(rt->dst.dev);
494 if (out_dev)
495 omi = IN_DEV_MEDIUM_ID(out_dev);
496
497 return omi != imi && omi != -1;
498 }
499
500 /*
501 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
502 *
503 * RFC3069 supports proxy arp replies back to the same interface. This
504 * is done to support (ethernet) switch features, like RFC 3069, where
505 * the individual ports are not allowed to communicate with each
506 * other, BUT they are allowed to talk to the upstream router. As
507 * described in RFC 3069, it is possible to allow these hosts to
508 * communicate through the upstream router, by proxy_arp'ing.
509 *
510 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
511 *
512 * This technology is known by different names:
513 * In RFC 3069 it is called VLAN Aggregation.
514 * Cisco and Allied Telesyn call it Private VLAN.
515 * Hewlett-Packard call it Source-Port filtering or port-isolation.
516 * Ericsson call it MAC-Forced Forwarding (RFC Draft).
517 *
518 */
519 static 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 */
545 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
546 struct net_device *dev, __be32 src_ip,
547 const unsigned char *dest_hw,
548 const unsigned char *src_hw,
549 const unsigned char *target_hw)
550 {
551 struct sk_buff *skb;
552 struct arphdr *arp;
553 unsigned char *arp_ptr;
554 int hlen = LL_RESERVED_SPACE(dev);
555 int tlen = dev->needed_tailroom;
556
557 /*
558 * Allocate a buffer
559 */
560
561 skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
562 if (!skb)
563 return NULL;
564
565 skb_reserve(skb, hlen);
566 skb_reset_network_header(skb);
567 arp = skb_put(skb, arp_hdr_len(dev));
568 skb->dev = dev;
569 skb->protocol = htons(ETH_P_ARP);
570 if (!src_hw)
571 src_hw = dev->dev_addr;
572 if (!dest_hw)
573 dest_hw = dev->broadcast;
574
575 /*
576 * Fill the device header for the ARP frame
577 */
578 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
579 goto out;
580
581 /*
582 * Fill out the arp protocol part.
583 *
584 * The arp hardware type should match the device type, except for FDDI,
585 * which (according to RFC 1390) should always equal 1 (Ethernet).
586 */
587 /*
588 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
589 * DIX code for the protocol. Make these device structure fields.
590 */
591 switch (dev->type) {
592 default:
593 arp->ar_hrd = htons(dev->type);
594 arp->ar_pro = htons(ETH_P_IP);
595 break;
596
597 #if IS_ENABLED(CONFIG_AX25)
598 case ARPHRD_AX25:
599 arp->ar_hrd = htons(ARPHRD_AX25);
600 arp->ar_pro = htons(AX25_P_IP);
601 break;
602
603 #if IS_ENABLED(CONFIG_NETROM)
604 case ARPHRD_NETROM:
605 arp->ar_hrd = htons(ARPHRD_NETROM);
606 arp->ar_pro = htons(AX25_P_IP);
607 break;
608 #endif
609 #endif
610
611 #if IS_ENABLED(CONFIG_FDDI)
612 case ARPHRD_FDDI:
613 arp->ar_hrd = htons(ARPHRD_ETHER);
614 arp->ar_pro = htons(ETH_P_IP);
615 break;
616 #endif
617 }
618
619 arp->ar_hln = dev->addr_len;
620 arp->ar_pln = 4;
621 arp->ar_op = htons(type);
622
623 arp_ptr = (unsigned char *)(arp + 1);
624
625 memcpy(arp_ptr, src_hw, dev->addr_len);
626 arp_ptr += dev->addr_len;
627 memcpy(arp_ptr, &src_ip, 4);
628 arp_ptr += 4;
629
630 switch (dev->type) {
631 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
632 case ARPHRD_IEEE1394:
633 break;
634 #endif
635 default:
636 if (target_hw)
637 memcpy(arp_ptr, target_hw, dev->addr_len);
638 else
639 memset(arp_ptr, 0, dev->addr_len);
640 arp_ptr += dev->addr_len;
641 }
642 memcpy(arp_ptr, &dest_ip, 4);
643
644 return skb;
645
646 out:
647 kfree_skb(skb);
648 return NULL;
649 }
650 EXPORT_SYMBOL(arp_create);
651
652 static 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 */
660 void arp_xmit(struct sk_buff *skb)
661 {
662 /* Send it off, maybe filter it using firewalling first. */
663 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT,
664 dev_net(skb->dev), NULL, skb, NULL, skb->dev,
665 arp_xmit_finish);
666 }
667 EXPORT_SYMBOL(arp_xmit);
668
669 static bool arp_is_garp(struct net *net, struct net_device *dev,
670 int *addr_type, __be16 ar_op,
671 __be32 sip, __be32 tip,
672 unsigned char *sha, unsigned char *tha)
673 {
674 bool is_garp = tip == sip;
675
676 /* Gratuitous ARP _replies_ also require target hwaddr to be
677 * the same as source.
678 */
679 if (is_garp && ar_op == htons(ARPOP_REPLY))
680 is_garp =
681 /* IPv4 over IEEE 1394 doesn't provide target
682 * hardware address field in its ARP payload.
683 */
684 tha &&
685 !memcmp(tha, sha, dev->addr_len);
686
687 if (is_garp) {
688 *addr_type = inet_addr_type_dev_table(net, dev, sip);
689 if (*addr_type != RTN_UNICAST)
690 is_garp = false;
691 }
692 return is_garp;
693 }
694
695 /*
696 * Process an arp request.
697 */
698
699 static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb)
700 {
701 struct net_device *dev = skb->dev;
702 struct in_device *in_dev = __in_dev_get_rcu(dev);
703 struct arphdr *arp;
704 unsigned char *arp_ptr;
705 struct rtable *rt;
706 unsigned char *sha;
707 unsigned char *tha = NULL;
708 __be32 sip, tip;
709 u16 dev_type = dev->type;
710 int addr_type;
711 struct neighbour *n;
712 struct dst_entry *reply_dst = NULL;
713 bool is_garp = false;
714
715 /* arp_rcv below verifies the ARP header and verifies the device
716 * is ARP'able.
717 */
718
719 if (!in_dev)
720 goto out_free_skb;
721
722 arp = arp_hdr(skb);
723
724 switch (dev_type) {
725 default:
726 if (arp->ar_pro != htons(ETH_P_IP) ||
727 htons(dev_type) != arp->ar_hrd)
728 goto out_free_skb;
729 break;
730 case ARPHRD_ETHER:
731 case ARPHRD_FDDI:
732 case ARPHRD_IEEE802:
733 /*
734 * ETHERNET, and Fibre Channel (which are IEEE 802
735 * devices, according to RFC 2625) devices will accept ARP
736 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
737 * This is the case also of FDDI, where the RFC 1390 says that
738 * FDDI devices should accept ARP hardware of (1) Ethernet,
739 * however, to be more robust, we'll accept both 1 (Ethernet)
740 * or 6 (IEEE 802.2)
741 */
742 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
743 arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
744 arp->ar_pro != htons(ETH_P_IP))
745 goto out_free_skb;
746 break;
747 case ARPHRD_AX25:
748 if (arp->ar_pro != htons(AX25_P_IP) ||
749 arp->ar_hrd != htons(ARPHRD_AX25))
750 goto out_free_skb;
751 break;
752 case ARPHRD_NETROM:
753 if (arp->ar_pro != htons(AX25_P_IP) ||
754 arp->ar_hrd != htons(ARPHRD_NETROM))
755 goto out_free_skb;
756 break;
757 }
758
759 /* Understand only these message types */
760
761 if (arp->ar_op != htons(ARPOP_REPLY) &&
762 arp->ar_op != htons(ARPOP_REQUEST))
763 goto out_free_skb;
764
765 /*
766 * Extract fields
767 */
768 arp_ptr = (unsigned char *)(arp + 1);
769 sha = arp_ptr;
770 arp_ptr += dev->addr_len;
771 memcpy(&sip, arp_ptr, 4);
772 arp_ptr += 4;
773 switch (dev_type) {
774 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
775 case ARPHRD_IEEE1394:
776 break;
777 #endif
778 default:
779 tha = arp_ptr;
780 arp_ptr += dev->addr_len;
781 }
782 memcpy(&tip, arp_ptr, 4);
783 /*
784 * Check for bad requests for 127.x.x.x and requests for multicast
785 * addresses. If this is one such, delete it.
786 */
787 if (ipv4_is_multicast(tip) ||
788 (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip)))
789 goto out_free_skb;
790
791 /*
792 * For some 802.11 wireless deployments (and possibly other networks),
793 * there will be an ARP proxy and gratuitous ARP frames are attacks
794 * and thus should not be accepted.
795 */
796 if (sip == tip && IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP))
797 goto out_free_skb;
798
799 /*
800 * Special case: We must set Frame Relay source Q.922 address
801 */
802 if (dev_type == ARPHRD_DLCI)
803 sha = dev->broadcast;
804
805 /*
806 * Process entry. The idea here is we want to send a reply if it is a
807 * request for us or if it is a request for someone else that we hold
808 * a proxy for. We want to add an entry to our cache if it is a reply
809 * to us or if it is a request for our address.
810 * (The assumption for this last is that if someone is requesting our
811 * address, they are probably intending to talk to us, so it saves time
812 * if we cache their address. Their address is also probably not in
813 * our cache, since ours is not in their cache.)
814 *
815 * Putting this another way, we only care about replies if they are to
816 * us, in which case we add them to the cache. For requests, we care
817 * about those for us and those for our proxies. We reply to both,
818 * and in the case of requests for us we add the requester to the arp
819 * cache.
820 */
821
822 if (arp->ar_op == htons(ARPOP_REQUEST) && skb_metadata_dst(skb))
823 reply_dst = (struct dst_entry *)
824 iptunnel_metadata_reply(skb_metadata_dst(skb),
825 GFP_ATOMIC);
826
827 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
828 if (sip == 0) {
829 if (arp->ar_op == htons(ARPOP_REQUEST) &&
830 inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL &&
831 !arp_ignore(in_dev, sip, tip))
832 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip,
833 sha, dev->dev_addr, sha, reply_dst);
834 goto out_consume_skb;
835 }
836
837 if (arp->ar_op == htons(ARPOP_REQUEST) &&
838 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
839
840 rt = skb_rtable(skb);
841 addr_type = rt->rt_type;
842
843 if (addr_type == RTN_LOCAL) {
844 int dont_send;
845
846 dont_send = arp_ignore(in_dev, sip, tip);
847 if (!dont_send && IN_DEV_ARPFILTER(in_dev))
848 dont_send = arp_filter(sip, tip, dev);
849 if (!dont_send) {
850 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
851 if (n) {
852 arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
853 sip, dev, tip, sha,
854 dev->dev_addr, sha,
855 reply_dst);
856 neigh_release(n);
857 }
858 }
859 goto out_consume_skb;
860 } else if (IN_DEV_FORWARD(in_dev)) {
861 if (addr_type == RTN_UNICAST &&
862 (arp_fwd_proxy(in_dev, dev, rt) ||
863 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
864 (rt->dst.dev != dev &&
865 pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
866 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
867 if (n)
868 neigh_release(n);
869
870 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
871 skb->pkt_type == PACKET_HOST ||
872 NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) {
873 arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
874 sip, dev, tip, sha,
875 dev->dev_addr, sha,
876 reply_dst);
877 } else {
878 pneigh_enqueue(&arp_tbl,
879 in_dev->arp_parms, skb);
880 goto out_free_dst;
881 }
882 goto out_consume_skb;
883 }
884 }
885 }
886
887 /* Update our ARP tables */
888
889 n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
890
891 addr_type = -1;
892 if (n || arp_accept(in_dev, sip)) {
893 is_garp = arp_is_garp(net, dev, &addr_type, arp->ar_op,
894 sip, tip, sha, tha);
895 }
896
897 if (arp_accept(in_dev, sip)) {
898 /* Unsolicited ARP is not accepted by default.
899 It is possible, that this option should be enabled for some
900 devices (strip is candidate)
901 */
902 if (!n &&
903 (is_garp ||
904 (arp->ar_op == htons(ARPOP_REPLY) &&
905 (addr_type == RTN_UNICAST ||
906 (addr_type < 0 &&
907 /* postpone calculation to as late as possible */
908 inet_addr_type_dev_table(net, dev, sip) ==
909 RTN_UNICAST)))))
910 n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
911 }
912
913 if (n) {
914 int state = NUD_REACHABLE;
915 int override;
916
917 /* If several different ARP replies follows back-to-back,
918 use the FIRST one. It is possible, if several proxy
919 agents are active. Taking the first reply prevents
920 arp trashing and chooses the fastest router.
921 */
922 override = time_after(jiffies,
923 n->updated +
924 NEIGH_VAR(n->parms, LOCKTIME)) ||
925 is_garp;
926
927 /* Broadcast replies and request packets
928 do not assert neighbour reachability.
929 */
930 if (arp->ar_op != htons(ARPOP_REPLY) ||
931 skb->pkt_type != PACKET_HOST)
932 state = NUD_STALE;
933 neigh_update(n, sha, state,
934 override ? NEIGH_UPDATE_F_OVERRIDE : 0, 0);
935 neigh_release(n);
936 }
937
938 out_consume_skb:
939 consume_skb(skb);
940
941 out_free_dst:
942 dst_release(reply_dst);
943 return NET_RX_SUCCESS;
944
945 out_free_skb:
946 kfree_skb(skb);
947 return NET_RX_DROP;
948 }
949
950 static void parp_redo(struct sk_buff *skb)
951 {
952 arp_process(dev_net(skb->dev), NULL, skb);
953 }
954
955 static int arp_is_multicast(const void *pkey)
956 {
957 return ipv4_is_multicast(*((__be32 *)pkey));
958 }
959
960 /*
961 * Receive an arp request from the device layer.
962 */
963
964 static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
965 struct packet_type *pt, struct net_device *orig_dev)
966 {
967 const struct arphdr *arp;
968
969 /* do not tweak dropwatch on an ARP we will ignore */
970 if (dev->flags & IFF_NOARP ||
971 skb->pkt_type == PACKET_OTHERHOST ||
972 skb->pkt_type == PACKET_LOOPBACK)
973 goto consumeskb;
974
975 skb = skb_share_check(skb, GFP_ATOMIC);
976 if (!skb)
977 goto out_of_mem;
978
979 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
980 if (!pskb_may_pull(skb, arp_hdr_len(dev)))
981 goto freeskb;
982
983 arp = arp_hdr(skb);
984 if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4)
985 goto freeskb;
986
987 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
988
989 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN,
990 dev_net(dev), NULL, skb, dev, NULL,
991 arp_process);
992
993 consumeskb:
994 consume_skb(skb);
995 return NET_RX_SUCCESS;
996 freeskb:
997 kfree_skb(skb);
998 out_of_mem:
999 return NET_RX_DROP;
1000 }
1001
1002 /*
1003 * User level interface (ioctl)
1004 */
1005
1006 static struct net_device *arp_req_dev_by_name(struct net *net, struct arpreq *r,
1007 bool getarp)
1008 {
1009 struct net_device *dev;
1010
1011 if (getarp)
1012 dev = dev_get_by_name_rcu(net, r->arp_dev);
1013 else
1014 dev = __dev_get_by_name(net, r->arp_dev);
1015 if (!dev)
1016 return ERR_PTR(-ENODEV);
1017
1018 /* Mmmm... It is wrong... ARPHRD_NETROM == 0 */
1019 if (!r->arp_ha.sa_family)
1020 r->arp_ha.sa_family = dev->type;
1021
1022 if ((r->arp_flags & ATF_COM) && r->arp_ha.sa_family != dev->type)
1023 return ERR_PTR(-EINVAL);
1024
1025 return dev;
1026 }
1027
1028 static struct net_device *arp_req_dev(struct net *net, struct arpreq *r)
1029 {
1030 struct net_device *dev;
1031 struct rtable *rt;
1032 __be32 ip;
1033
1034 if (r->arp_dev[0])
1035 return arp_req_dev_by_name(net, r, false);
1036
1037 if (r->arp_flags & ATF_PUBL)
1038 return NULL;
1039
1040 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1041
1042 rt = ip_route_output(net, ip, 0, 0, 0, RT_SCOPE_LINK);
1043 if (IS_ERR(rt))
1044 return ERR_CAST(rt);
1045
1046 dev = rt->dst.dev;
1047 ip_rt_put(rt);
1048
1049 if (!dev)
1050 return ERR_PTR(-EINVAL);
1051
1052 return dev;
1053 }
1054
1055 /*
1056 * Set (create) an ARP cache entry.
1057 */
1058
1059 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
1060 {
1061 if (!dev) {
1062 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
1063 return 0;
1064 }
1065 if (__in_dev_get_rtnl(dev)) {
1066 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
1067 return 0;
1068 }
1069 return -ENXIO;
1070 }
1071
1072 static int arp_req_set_public(struct net *net, struct arpreq *r,
1073 struct net_device *dev)
1074 {
1075 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1076
1077 if (!dev && (r->arp_flags & ATF_COM)) {
1078 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family,
1079 r->arp_ha.sa_data);
1080 if (!dev)
1081 return -ENODEV;
1082 }
1083 if (mask) {
1084 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1085
1086 if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1))
1087 return -ENOBUFS;
1088 return 0;
1089 }
1090
1091 return arp_req_set_proxy(net, dev, 1);
1092 }
1093
1094 static int arp_req_set(struct net *net, struct arpreq *r)
1095 {
1096 struct neighbour *neigh;
1097 struct net_device *dev;
1098 __be32 ip;
1099 int err;
1100
1101 dev = arp_req_dev(net, r);
1102 if (IS_ERR(dev))
1103 return PTR_ERR(dev);
1104
1105 if (r->arp_flags & ATF_PUBL)
1106 return arp_req_set_public(net, r, dev);
1107
1108 switch (dev->type) {
1109 #if IS_ENABLED(CONFIG_FDDI)
1110 case ARPHRD_FDDI:
1111 /*
1112 * According to RFC 1390, FDDI devices should accept ARP
1113 * hardware types of 1 (Ethernet). However, to be more
1114 * robust, we'll accept hardware types of either 1 (Ethernet)
1115 * or 6 (IEEE 802.2).
1116 */
1117 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1118 r->arp_ha.sa_family != ARPHRD_ETHER &&
1119 r->arp_ha.sa_family != ARPHRD_IEEE802)
1120 return -EINVAL;
1121 break;
1122 #endif
1123 default:
1124 if (r->arp_ha.sa_family != dev->type)
1125 return -EINVAL;
1126 break;
1127 }
1128
1129 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1130
1131 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1132 err = PTR_ERR(neigh);
1133 if (!IS_ERR(neigh)) {
1134 unsigned int state = NUD_STALE;
1135
1136 if (r->arp_flags & ATF_PERM) {
1137 r->arp_flags |= ATF_COM;
1138 state = NUD_PERMANENT;
1139 }
1140
1141 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ?
1142 r->arp_ha.sa_data : NULL, state,
1143 NEIGH_UPDATE_F_OVERRIDE |
1144 NEIGH_UPDATE_F_ADMIN, 0);
1145 neigh_release(neigh);
1146 }
1147 return err;
1148 }
1149
1150 static unsigned int arp_state_to_flags(struct neighbour *neigh)
1151 {
1152 if (neigh->nud_state&NUD_PERMANENT)
1153 return ATF_PERM | ATF_COM;
1154 else if (neigh->nud_state&NUD_VALID)
1155 return ATF_COM;
1156 else
1157 return 0;
1158 }
1159
1160 /*
1161 * Get an ARP cache entry.
1162 */
1163
1164 static int arp_req_get(struct net *net, struct arpreq *r)
1165 {
1166 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1167 struct neighbour *neigh;
1168 struct net_device *dev;
1169
1170 if (!r->arp_dev[0])
1171 return -ENODEV;
1172
1173 dev = arp_req_dev_by_name(net, r, true);
1174 if (IS_ERR(dev))
1175 return PTR_ERR(dev);
1176
1177 neigh = neigh_lookup(&arp_tbl, &ip, dev);
1178 if (!neigh)
1179 return -ENXIO;
1180
1181 if (READ_ONCE(neigh->nud_state) & NUD_NOARP) {
1182 neigh_release(neigh);
1183 return -ENXIO;
1184 }
1185
1186 read_lock_bh(&neigh->lock);
1187 memcpy(r->arp_ha.sa_data, neigh->ha,
1188 min(dev->addr_len, sizeof(r->arp_ha.sa_data_min)));
1189 r->arp_flags = arp_state_to_flags(neigh);
1190 read_unlock_bh(&neigh->lock);
1191
1192 neigh_release(neigh);
1193
1194 r->arp_ha.sa_family = dev->type;
1195 netdev_copy_name(dev, r->arp_dev);
1196
1197 return 0;
1198 }
1199
1200 int arp_invalidate(struct net_device *dev, __be32 ip, bool force)
1201 {
1202 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
1203 int err = -ENXIO;
1204 struct neigh_table *tbl = &arp_tbl;
1205
1206 if (neigh) {
1207 if ((READ_ONCE(neigh->nud_state) & NUD_VALID) && !force) {
1208 neigh_release(neigh);
1209 return 0;
1210 }
1211
1212 if (READ_ONCE(neigh->nud_state) & ~NUD_NOARP)
1213 err = neigh_update(neigh, NULL, NUD_FAILED,
1214 NEIGH_UPDATE_F_OVERRIDE|
1215 NEIGH_UPDATE_F_ADMIN, 0);
1216 write_lock_bh(&tbl->lock);
1217 neigh_release(neigh);
1218 neigh_remove_one(neigh, tbl);
1219 write_unlock_bh(&tbl->lock);
1220 }
1221
1222 return err;
1223 }
1224
1225 static int arp_req_delete_public(struct net *net, struct arpreq *r,
1226 struct net_device *dev)
1227 {
1228 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1229
1230 if (mask) {
1231 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1232
1233 return pneigh_delete(&arp_tbl, net, &ip, dev);
1234 }
1235
1236 return arp_req_set_proxy(net, dev, 0);
1237 }
1238
1239 static int arp_req_delete(struct net *net, struct arpreq *r)
1240 {
1241 struct net_device *dev;
1242 __be32 ip;
1243
1244 dev = arp_req_dev(net, r);
1245 if (IS_ERR(dev))
1246 return PTR_ERR(dev);
1247
1248 if (r->arp_flags & ATF_PUBL)
1249 return arp_req_delete_public(net, r, dev);
1250
1251 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1252
1253 return arp_invalidate(dev, ip, true);
1254 }
1255
1256 /*
1257 * Handle an ARP layer I/O control request.
1258 */
1259
1260 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1261 {
1262 struct arpreq r;
1263 __be32 *netmask;
1264 int err;
1265
1266 switch (cmd) {
1267 case SIOCDARP:
1268 case SIOCSARP:
1269 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1270 return -EPERM;
1271 fallthrough;
1272 case SIOCGARP:
1273 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1274 if (err)
1275 return -EFAULT;
1276 break;
1277 default:
1278 return -EINVAL;
1279 }
1280
1281 if (r.arp_pa.sa_family != AF_INET)
1282 return -EPFNOSUPPORT;
1283
1284 if (!(r.arp_flags & ATF_PUBL) &&
1285 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1286 return -EINVAL;
1287
1288 netmask = &((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr;
1289 if (!(r.arp_flags & ATF_NETMASK))
1290 *netmask = htonl(0xFFFFFFFFUL);
1291 else if (*netmask && *netmask != htonl(0xFFFFFFFFUL))
1292 return -EINVAL;
1293
1294 switch (cmd) {
1295 case SIOCDARP:
1296 rtnl_lock();
1297 err = arp_req_delete(net, &r);
1298 rtnl_unlock();
1299 break;
1300 case SIOCSARP:
1301 rtnl_lock();
1302 err = arp_req_set(net, &r);
1303 rtnl_unlock();
1304 break;
1305 case SIOCGARP:
1306 rcu_read_lock();
1307 err = arp_req_get(net, &r);
1308 rcu_read_unlock();
1309
1310 if (!err && copy_to_user(arg, &r, sizeof(r)))
1311 err = -EFAULT;
1312 break;
1313 }
1314
1315 return err;
1316 }
1317
1318 static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1319 void *ptr)
1320 {
1321 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
1322 struct netdev_notifier_change_info *change_info;
1323 struct in_device *in_dev;
1324 bool evict_nocarrier;
1325
1326 switch (event) {
1327 case NETDEV_CHANGEADDR:
1328 neigh_changeaddr(&arp_tbl, dev);
1329 rt_cache_flush(dev_net(dev));
1330 break;
1331 case NETDEV_CHANGE:
1332 change_info = ptr;
1333 if (change_info->flags_changed & IFF_NOARP)
1334 neigh_changeaddr(&arp_tbl, dev);
1335
1336 in_dev = __in_dev_get_rtnl(dev);
1337 if (!in_dev)
1338 evict_nocarrier = true;
1339 else
1340 evict_nocarrier = IN_DEV_ARP_EVICT_NOCARRIER(in_dev);
1341
1342 if (evict_nocarrier && !netif_carrier_ok(dev))
1343 neigh_carrier_down(&arp_tbl, dev);
1344 break;
1345 default:
1346 break;
1347 }
1348
1349 return NOTIFY_DONE;
1350 }
1351
1352 static struct notifier_block arp_netdev_notifier = {
1353 .notifier_call = arp_netdev_event,
1354 };
1355
1356 /* Note, that it is not on notifier chain.
1357 It is necessary, that this routine was called after route cache will be
1358 flushed.
1359 */
1360 void arp_ifdown(struct net_device *dev)
1361 {
1362 neigh_ifdown(&arp_tbl, dev);
1363 }
1364
1365
1366 /*
1367 * Called once on startup.
1368 */
1369
1370 static struct packet_type arp_packet_type __read_mostly = {
1371 .type = cpu_to_be16(ETH_P_ARP),
1372 .func = arp_rcv,
1373 };
1374
1375 #ifdef CONFIG_PROC_FS
1376 #if IS_ENABLED(CONFIG_AX25)
1377
1378 /*
1379 * ax25 -> ASCII conversion
1380 */
1381 static void ax2asc2(ax25_address *a, char *buf)
1382 {
1383 char c, *s;
1384 int n;
1385
1386 for (n = 0, s = buf; n < 6; n++) {
1387 c = (a->ax25_call[n] >> 1) & 0x7F;
1388
1389 if (c != ' ')
1390 *s++ = c;
1391 }
1392
1393 *s++ = '-';
1394 n = (a->ax25_call[6] >> 1) & 0x0F;
1395 if (n > 9) {
1396 *s++ = '1';
1397 n -= 10;
1398 }
1399
1400 *s++ = n + '';
1401 *s++ = '\0';
1402
1403 if (*buf == '\0' || *buf == '-') {
1404 buf[0] = '*';
1405 buf[1] = '\0';
1406 }
1407 }
1408 #endif /* CONFIG_AX25 */
1409
1410 #define HBUFFERLEN 30
1411
1412 static void arp_format_neigh_entry(struct seq_file *seq,
1413 struct neighbour *n)
1414 {
1415 char hbuffer[HBUFFERLEN];
1416 int k, j;
1417 char tbuf[16];
1418 struct net_device *dev = n->dev;
1419 int hatype = dev->type;
1420
1421 read_lock(&n->lock);
1422 /* Convert hardware address to XX:XX:XX:XX ... form. */
1423 #if IS_ENABLED(CONFIG_AX25)
1424 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1425 ax2asc2((ax25_address *)n->ha, hbuffer);
1426 else {
1427 #endif
1428 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1429 hbuffer[k++] = hex_asc_hi(n->ha[j]);
1430 hbuffer[k++] = hex_asc_lo(n->ha[j]);
1431 hbuffer[k++] = ':';
1432 }
1433 if (k != 0)
1434 --k;
1435 hbuffer[k] = 0;
1436 #if IS_ENABLED(CONFIG_AX25)
1437 }
1438 #endif
1439 sprintf(tbuf, "%pI4", n->primary_key);
1440 seq_printf(seq, "%-16s 0x%-10x0x%-10x%-17s * %s\n",
1441 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1442 read_unlock(&n->lock);
1443 }
1444
1445 static void arp_format_pneigh_entry(struct seq_file *seq,
1446 struct pneigh_entry *n)
1447 {
1448 struct net_device *dev = n->dev;
1449 int hatype = dev ? dev->type : 0;
1450 char tbuf[16];
1451
1452 sprintf(tbuf, "%pI4", n->key);
1453 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1454 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1455 dev ? dev->name : "*");
1456 }
1457
1458 static int arp_seq_show(struct seq_file *seq, void *v)
1459 {
1460 if (v == SEQ_START_TOKEN) {
1461 seq_puts(seq, "IP address HW type Flags "
1462 "HW address Mask Device\n");
1463 } else {
1464 struct neigh_seq_state *state = seq->private;
1465
1466 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1467 arp_format_pneigh_entry(seq, v);
1468 else
1469 arp_format_neigh_entry(seq, v);
1470 }
1471
1472 return 0;
1473 }
1474
1475 static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1476 {
1477 /* Don't want to confuse "arp -a" w/ magic entries,
1478 * so we tell the generic iterator to skip NUD_NOARP.
1479 */
1480 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1481 }
1482
1483 static const struct seq_operations arp_seq_ops = {
1484 .start = arp_seq_start,
1485 .next = neigh_seq_next,
1486 .stop = neigh_seq_stop,
1487 .show = arp_seq_show,
1488 };
1489 #endif /* CONFIG_PROC_FS */
1490
1491 static int __net_init arp_net_init(struct net *net)
1492 {
1493 if (!proc_create_net("arp", 0444, net->proc_net, &arp_seq_ops,
1494 sizeof(struct neigh_seq_state)))
1495 return -ENOMEM;
1496 return 0;
1497 }
1498
1499 static void __net_exit arp_net_exit(struct net *net)
1500 {
1501 remove_proc_entry("arp", net->proc_net);
1502 }
1503
1504 static struct pernet_operations arp_net_ops = {
1505 .init = arp_net_init,
1506 .exit = arp_net_exit,
1507 };
1508
1509 void __init arp_init(void)
1510 {
1511 neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl);
1512
1513 dev_add_pack(&arp_packet_type);
1514 register_pernet_subsys(&arp_net_ops);
1515 #ifdef CONFIG_SYSCTL
1516 neigh_sysctl_register(NULL, &arp_tbl.parms, NULL);
1517 #endif
1518 register_netdevice_notifier(&arp_netdev_notifier);
1519 }
1520
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.