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_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 };
184 EXPORT_SYMBOL(arp_tbl);
185
arp_mc_map(__be32 addr,u8 * haddr,struct net_device * dev,int dir)186 int 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
arp_hash(const void * pkey,const struct net_device * dev,__u32 * hash_rnd)210 static 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
arp_key_eq(const struct neighbour * neigh,const void * pkey)217 static bool arp_key_eq(const struct neighbour *neigh, const void *pkey)
218 {
219 return neigh_key_eq32(neigh, pkey);
220 }
221
arp_constructor(struct neighbour * neigh)222 static 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
arp_error_report(struct neighbour * neigh,struct sk_buff * skb)293 static 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. */
arp_send_dst(int type,int ptype,__be32 dest_ip,struct net_device * dev,__be32 src_ip,const unsigned char * dest_hw,const unsigned char * src_hw,const unsigned char * target_hw,struct dst_entry * dst)300 static 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
arp_send(int type,int ptype,__be32 dest_ip,struct net_device * dev,__be32 src_ip,const unsigned char * dest_hw,const unsigned char * src_hw,const unsigned char * target_hw)322 void 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 }
330 EXPORT_SYMBOL(arp_send);
331
arp_solicit(struct neighbour * neigh,struct sk_buff * skb)332 static 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
arp_ignore(struct in_device * in_dev,__be32 sip,__be32 tip)395 static 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
arp_filter(__be32 sip,__be32 tip,struct net_device * dev)431 static 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 */
arp_fwd_proxy(struct in_device * in_dev,struct net_device * dev,struct rtable * rt)452 static 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 */
arp_fwd_pvlan(struct in_device * in_dev,struct net_device * dev,struct rtable * rt,__be32 sip,__be32 tip)497 static 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 */
arp_create(int type,int ptype,__be32 dest_ip,struct net_device * dev,__be32 src_ip,const unsigned char * dest_hw,const unsigned char * src_hw,const unsigned char * target_hw)523 struct 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
624 out:
625 kfree_skb(skb);
626 return NULL;
627 }
628 EXPORT_SYMBOL(arp_create);
629
arp_xmit_finish(struct net * net,struct sock * sk,struct sk_buff * skb)630 static 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 */
arp_xmit(struct sk_buff * skb)638 void 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 }
645 EXPORT_SYMBOL(arp_xmit);
646
arp_is_garp(struct net * net,struct net_device * dev,int * addr_type,__be16 ar_op,__be32 sip,__be32 tip,unsigned char * sha,unsigned char * tha)647 static 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
arp_process(struct net * net,struct sock * sk,struct sk_buff * skb)677 static 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
916 out_consume_skb:
917 consume_skb(skb);
918
919 out_free_dst:
920 dst_release(reply_dst);
921 return NET_RX_SUCCESS;
922
923 out_free_skb:
924 kfree_skb(skb);
925 return NET_RX_DROP;
926 }
927
parp_redo(struct sk_buff * skb)928 static void parp_redo(struct sk_buff *skb)
929 {
930 arp_process(dev_net(skb->dev), NULL, skb);
931 }
932
arp_is_multicast(const void * pkey)933 static 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
arp_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt,struct net_device * orig_dev)942 static 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
971 consumeskb:
972 consume_skb(skb);
973 return NET_RX_SUCCESS;
974 freeskb:
975 kfree_skb(skb);
976 out_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
arp_req_set_proxy(struct net * net,struct net_device * dev,int on)988 static 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
arp_req_set_public(struct net * net,struct arpreq * r,struct net_device * dev)1001 static 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
arp_req_set(struct net * net,struct arpreq * r,struct net_device * dev)1024 static 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
arp_state_to_flags(struct neighbour * neigh)1083 static 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
arp_req_get(struct arpreq * r,struct net_device * dev)1097 static 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
arp_invalidate(struct net_device * dev,__be32 ip,bool force)1119 int arp_invalidate(struct net_device *dev, __be32 ip, bool force)
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_VALID) && !force) {
1127 neigh_release(neigh);
1128 return 0;
1129 }
1130
1131 if (neigh->nud_state & ~NUD_NOARP)
1132 err = neigh_update(neigh, NULL, NUD_FAILED,
1133 NEIGH_UPDATE_F_OVERRIDE|
1134 NEIGH_UPDATE_F_ADMIN, 0);
1135 write_lock_bh(&tbl->lock);
1136 neigh_release(neigh);
1137 neigh_remove_one(neigh, tbl);
1138 write_unlock_bh(&tbl->lock);
1139 }
1140
1141 return err;
1142 }
1143
arp_req_delete_public(struct net * net,struct arpreq * r,struct net_device * dev)1144 static int arp_req_delete_public(struct net *net, struct arpreq *r,
1145 struct net_device *dev)
1146 {
1147 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1148 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1149
1150 if (mask == htonl(0xFFFFFFFF))
1151 return pneigh_delete(&arp_tbl, net, &ip, dev);
1152
1153 if (mask)
1154 return -EINVAL;
1155
1156 return arp_req_set_proxy(net, dev, 0);
1157 }
1158
arp_req_delete(struct net * net,struct arpreq * r,struct net_device * dev)1159 static int arp_req_delete(struct net *net, struct arpreq *r,
1160 struct net_device *dev)
1161 {
1162 __be32 ip;
1163
1164 if (r->arp_flags & ATF_PUBL)
1165 return arp_req_delete_public(net, r, dev);
1166
1167 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1168 if (!dev) {
1169 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1170 if (IS_ERR(rt))
1171 return PTR_ERR(rt);
1172 dev = rt->dst.dev;
1173 ip_rt_put(rt);
1174 if (!dev)
1175 return -EINVAL;
1176 }
1177 return arp_invalidate(dev, ip, true);
1178 }
1179
1180 /*
1181 * Handle an ARP layer I/O control request.
1182 */
1183
arp_ioctl(struct net * net,unsigned int cmd,void __user * arg)1184 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1185 {
1186 int err;
1187 struct arpreq r;
1188 struct net_device *dev = NULL;
1189
1190 switch (cmd) {
1191 case SIOCDARP:
1192 case SIOCSARP:
1193 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1194 return -EPERM;
1195 fallthrough;
1196 case SIOCGARP:
1197 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1198 if (err)
1199 return -EFAULT;
1200 break;
1201 default:
1202 return -EINVAL;
1203 }
1204
1205 if (r.arp_pa.sa_family != AF_INET)
1206 return -EPFNOSUPPORT;
1207
1208 if (!(r.arp_flags & ATF_PUBL) &&
1209 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1210 return -EINVAL;
1211 if (!(r.arp_flags & ATF_NETMASK))
1212 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1213 htonl(0xFFFFFFFFUL);
1214 rtnl_lock();
1215 if (r.arp_dev[0]) {
1216 err = -ENODEV;
1217 dev = __dev_get_by_name(net, r.arp_dev);
1218 if (!dev)
1219 goto out;
1220
1221 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1222 if (!r.arp_ha.sa_family)
1223 r.arp_ha.sa_family = dev->type;
1224 err = -EINVAL;
1225 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1226 goto out;
1227 } else if (cmd == SIOCGARP) {
1228 err = -ENODEV;
1229 goto out;
1230 }
1231
1232 switch (cmd) {
1233 case SIOCDARP:
1234 err = arp_req_delete(net, &r, dev);
1235 break;
1236 case SIOCSARP:
1237 err = arp_req_set(net, &r, dev);
1238 break;
1239 case SIOCGARP:
1240 err = arp_req_get(&r, dev);
1241 break;
1242 }
1243 out:
1244 rtnl_unlock();
1245 if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
1246 err = -EFAULT;
1247 return err;
1248 }
1249
arp_netdev_event(struct notifier_block * this,unsigned long event,void * ptr)1250 static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1251 void *ptr)
1252 {
1253 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
1254 struct netdev_notifier_change_info *change_info;
1255
1256 switch (event) {
1257 case NETDEV_CHANGEADDR:
1258 neigh_changeaddr(&arp_tbl, dev);
1259 rt_cache_flush(dev_net(dev));
1260 break;
1261 case NETDEV_CHANGE:
1262 change_info = ptr;
1263 if (change_info->flags_changed & IFF_NOARP)
1264 neigh_changeaddr(&arp_tbl, dev);
1265 if (!netif_carrier_ok(dev))
1266 neigh_carrier_down(&arp_tbl, dev);
1267 break;
1268 default:
1269 break;
1270 }
1271
1272 return NOTIFY_DONE;
1273 }
1274
1275 static struct notifier_block arp_netdev_notifier = {
1276 .notifier_call = arp_netdev_event,
1277 };
1278
1279 /* Note, that it is not on notifier chain.
1280 It is necessary, that this routine was called after route cache will be
1281 flushed.
1282 */
arp_ifdown(struct net_device * dev)1283 void arp_ifdown(struct net_device *dev)
1284 {
1285 neigh_ifdown(&arp_tbl, dev);
1286 }
1287
1288
1289 /*
1290 * Called once on startup.
1291 */
1292
1293 static struct packet_type arp_packet_type __read_mostly = {
1294 .type = cpu_to_be16(ETH_P_ARP),
1295 .func = arp_rcv,
1296 };
1297
1298 static int arp_proc_init(void);
1299
arp_init(void)1300 void __init arp_init(void)
1301 {
1302 neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl);
1303
1304 dev_add_pack(&arp_packet_type);
1305 arp_proc_init();
1306 #ifdef CONFIG_SYSCTL
1307 neigh_sysctl_register(NULL, &arp_tbl.parms, NULL);
1308 #endif
1309 register_netdevice_notifier(&arp_netdev_notifier);
1310 }
1311
1312 #ifdef CONFIG_PROC_FS
1313 #if IS_ENABLED(CONFIG_AX25)
1314
1315 /* ------------------------------------------------------------------------ */
1316 /*
1317 * ax25 -> ASCII conversion
1318 */
ax2asc2(ax25_address * a,char * buf)1319 static void ax2asc2(ax25_address *a, char *buf)
1320 {
1321 char c, *s;
1322 int n;
1323
1324 for (n = 0, s = buf; n < 6; n++) {
1325 c = (a->ax25_call[n] >> 1) & 0x7F;
1326
1327 if (c != ' ')
1328 *s++ = c;
1329 }
1330
1331 *s++ = '-';
1332 n = (a->ax25_call[6] >> 1) & 0x0F;
1333 if (n > 9) {
1334 *s++ = '1';
1335 n -= 10;
1336 }
1337
1338 *s++ = n + '0';
1339 *s++ = '\0';
1340
1341 if (*buf == '\0' || *buf == '-') {
1342 buf[0] = '*';
1343 buf[1] = '\0';
1344 }
1345 }
1346 #endif /* CONFIG_AX25 */
1347
1348 #define HBUFFERLEN 30
1349
arp_format_neigh_entry(struct seq_file * seq,struct neighbour * n)1350 static void arp_format_neigh_entry(struct seq_file *seq,
1351 struct neighbour *n)
1352 {
1353 char hbuffer[HBUFFERLEN];
1354 int k, j;
1355 char tbuf[16];
1356 struct net_device *dev = n->dev;
1357 int hatype = dev->type;
1358
1359 read_lock(&n->lock);
1360 /* Convert hardware address to XX:XX:XX:XX ... form. */
1361 #if IS_ENABLED(CONFIG_AX25)
1362 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1363 ax2asc2((ax25_address *)n->ha, hbuffer);
1364 else {
1365 #endif
1366 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1367 hbuffer[k++] = hex_asc_hi(n->ha[j]);
1368 hbuffer[k++] = hex_asc_lo(n->ha[j]);
1369 hbuffer[k++] = ':';
1370 }
1371 if (k != 0)
1372 --k;
1373 hbuffer[k] = 0;
1374 #if IS_ENABLED(CONFIG_AX25)
1375 }
1376 #endif
1377 sprintf(tbuf, "%pI4", n->primary_key);
1378 seq_printf(seq, "%-16s 0x%-10x0x%-10x%-17s * %s\n",
1379 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1380 read_unlock(&n->lock);
1381 }
1382
arp_format_pneigh_entry(struct seq_file * seq,struct pneigh_entry * n)1383 static void arp_format_pneigh_entry(struct seq_file *seq,
1384 struct pneigh_entry *n)
1385 {
1386 struct net_device *dev = n->dev;
1387 int hatype = dev ? dev->type : 0;
1388 char tbuf[16];
1389
1390 sprintf(tbuf, "%pI4", n->key);
1391 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1392 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1393 dev ? dev->name : "*");
1394 }
1395
arp_seq_show(struct seq_file * seq,void * v)1396 static int arp_seq_show(struct seq_file *seq, void *v)
1397 {
1398 if (v == SEQ_START_TOKEN) {
1399 seq_puts(seq, "IP address HW type Flags "
1400 "HW address Mask Device\n");
1401 } else {
1402 struct neigh_seq_state *state = seq->private;
1403
1404 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1405 arp_format_pneigh_entry(seq, v);
1406 else
1407 arp_format_neigh_entry(seq, v);
1408 }
1409
1410 return 0;
1411 }
1412
arp_seq_start(struct seq_file * seq,loff_t * pos)1413 static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1414 {
1415 /* Don't want to confuse "arp -a" w/ magic entries,
1416 * so we tell the generic iterator to skip NUD_NOARP.
1417 */
1418 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1419 }
1420
1421 /* ------------------------------------------------------------------------ */
1422
1423 static const struct seq_operations arp_seq_ops = {
1424 .start = arp_seq_start,
1425 .next = neigh_seq_next,
1426 .stop = neigh_seq_stop,
1427 .show = arp_seq_show,
1428 };
1429
1430 /* ------------------------------------------------------------------------ */
1431
arp_net_init(struct net * net)1432 static int __net_init arp_net_init(struct net *net)
1433 {
1434 if (!proc_create_net("arp", 0444, net->proc_net, &arp_seq_ops,
1435 sizeof(struct neigh_seq_state)))
1436 return -ENOMEM;
1437 return 0;
1438 }
1439
arp_net_exit(struct net * net)1440 static void __net_exit arp_net_exit(struct net *net)
1441 {
1442 remove_proc_entry("arp", net->proc_net);
1443 }
1444
1445 static struct pernet_operations arp_net_ops = {
1446 .init = arp_net_init,
1447 .exit = arp_net_exit,
1448 };
1449
arp_proc_init(void)1450 static int __init arp_proc_init(void)
1451 {
1452 return register_pernet_subsys(&arp_net_ops);
1453 }
1454
1455 #else /* CONFIG_PROC_FS */
1456
arp_proc_init(void)1457 static int __init arp_proc_init(void)
1458 {
1459 return 0;
1460 }
1461
1462 #endif /* CONFIG_PROC_FS */
1463