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
arp_mc_map(__be32 addr,u8 * haddr,struct net_device * dev,int dir)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
arp_hash(const void * pkey,const struct net_device * dev,__u32 * hash_rnd)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
arp_key_eq(const struct neighbour * neigh,const void * pkey)218 static bool arp_key_eq(const struct neighbour *neigh, const void *pkey)
219 {
220 return neigh_key_eq32(neigh, pkey);
221 }
222
arp_constructor(struct neighbour * neigh)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
arp_error_report(struct neighbour * neigh,struct sk_buff * skb)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. */
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)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
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)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
arp_solicit(struct neighbour * neigh,struct sk_buff * skb)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
arp_ignore(struct in_device * in_dev,__be32 sip,__be32 tip)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
arp_accept(struct in_device * in_dev,__be32 sip)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
arp_filter(__be32 sip,__be32 tip,struct net_device * dev)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 if (IS_ERR(rt))
461 return 1;
462 if (rt->dst.dev != dev) {
463 __NET_INC_STATS(net, LINUX_MIB_ARPFILTER);
464 flag = 1;
465 }
466 ip_rt_put(rt);
467 return flag;
468 }
469
470 /*
471 * Check if we can use proxy ARP for this path
472 */
arp_fwd_proxy(struct in_device * in_dev,struct net_device * dev,struct rtable * rt)473 static inline int arp_fwd_proxy(struct in_device *in_dev,
474 struct net_device *dev, struct rtable *rt)
475 {
476 struct in_device *out_dev;
477 int imi, omi = -1;
478
479 if (rt->dst.dev == dev)
480 return 0;
481
482 if (!IN_DEV_PROXY_ARP(in_dev))
483 return 0;
484 imi = IN_DEV_MEDIUM_ID(in_dev);
485 if (imi == 0)
486 return 1;
487 if (imi == -1)
488 return 0;
489
490 /* place to check for proxy_arp for routes */
491
492 out_dev = __in_dev_get_rcu(rt->dst.dev);
493 if (out_dev)
494 omi = IN_DEV_MEDIUM_ID(out_dev);
495
496 return omi != imi && omi != -1;
497 }
498
499 /*
500 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
501 *
502 * RFC3069 supports proxy arp replies back to the same interface. This
503 * is done to support (ethernet) switch features, like RFC 3069, where
504 * the individual ports are not allowed to communicate with each
505 * other, BUT they are allowed to talk to the upstream router. As
506 * described in RFC 3069, it is possible to allow these hosts to
507 * communicate through the upstream router, by proxy_arp'ing.
508 *
509 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
510 *
511 * This technology is known by different names:
512 * In RFC 3069 it is called VLAN Aggregation.
513 * Cisco and Allied Telesyn call it Private VLAN.
514 * Hewlett-Packard call it Source-Port filtering or port-isolation.
515 * Ericsson call it MAC-Forced Forwarding (RFC Draft).
516 *
517 */
arp_fwd_pvlan(struct in_device * in_dev,struct net_device * dev,struct rtable * rt,__be32 sip,__be32 tip)518 static inline int arp_fwd_pvlan(struct in_device *in_dev,
519 struct net_device *dev, struct rtable *rt,
520 __be32 sip, __be32 tip)
521 {
522 /* Private VLAN is only concerned about the same ethernet segment */
523 if (rt->dst.dev != dev)
524 return 0;
525
526 /* Don't reply on self probes (often done by windowz boxes)*/
527 if (sip == tip)
528 return 0;
529
530 if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
531 return 1;
532 else
533 return 0;
534 }
535
536 /*
537 * Interface to link layer: send routine and receive handler.
538 */
539
540 /*
541 * Create an arp packet. If dest_hw is not set, we create a broadcast
542 * message.
543 */
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)544 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
545 struct net_device *dev, __be32 src_ip,
546 const unsigned char *dest_hw,
547 const unsigned char *src_hw,
548 const unsigned char *target_hw)
549 {
550 struct sk_buff *skb;
551 struct arphdr *arp;
552 unsigned char *arp_ptr;
553 int hlen = LL_RESERVED_SPACE(dev);
554 int tlen = dev->needed_tailroom;
555
556 /*
557 * Allocate a buffer
558 */
559
560 skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
561 if (!skb)
562 return NULL;
563
564 skb_reserve(skb, hlen);
565 skb_reset_network_header(skb);
566 arp = skb_put(skb, arp_hdr_len(dev));
567 skb->dev = dev;
568 skb->protocol = htons(ETH_P_ARP);
569 if (!src_hw)
570 src_hw = dev->dev_addr;
571 if (!dest_hw)
572 dest_hw = dev->broadcast;
573
574 /*
575 * Fill the device header for the ARP frame
576 */
577 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
578 goto out;
579
580 /*
581 * Fill out the arp protocol part.
582 *
583 * The arp hardware type should match the device type, except for FDDI,
584 * which (according to RFC 1390) should always equal 1 (Ethernet).
585 */
586 /*
587 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
588 * DIX code for the protocol. Make these device structure fields.
589 */
590 switch (dev->type) {
591 default:
592 arp->ar_hrd = htons(dev->type);
593 arp->ar_pro = htons(ETH_P_IP);
594 break;
595
596 #if IS_ENABLED(CONFIG_AX25)
597 case ARPHRD_AX25:
598 arp->ar_hrd = htons(ARPHRD_AX25);
599 arp->ar_pro = htons(AX25_P_IP);
600 break;
601
602 #if IS_ENABLED(CONFIG_NETROM)
603 case ARPHRD_NETROM:
604 arp->ar_hrd = htons(ARPHRD_NETROM);
605 arp->ar_pro = htons(AX25_P_IP);
606 break;
607 #endif
608 #endif
609
610 #if IS_ENABLED(CONFIG_FDDI)
611 case ARPHRD_FDDI:
612 arp->ar_hrd = htons(ARPHRD_ETHER);
613 arp->ar_pro = htons(ETH_P_IP);
614 break;
615 #endif
616 }
617
618 arp->ar_hln = dev->addr_len;
619 arp->ar_pln = 4;
620 arp->ar_op = htons(type);
621
622 arp_ptr = (unsigned char *)(arp + 1);
623
624 memcpy(arp_ptr, src_hw, dev->addr_len);
625 arp_ptr += dev->addr_len;
626 memcpy(arp_ptr, &src_ip, 4);
627 arp_ptr += 4;
628
629 switch (dev->type) {
630 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
631 case ARPHRD_IEEE1394:
632 break;
633 #endif
634 default:
635 if (target_hw)
636 memcpy(arp_ptr, target_hw, dev->addr_len);
637 else
638 memset(arp_ptr, 0, dev->addr_len);
639 arp_ptr += dev->addr_len;
640 }
641 memcpy(arp_ptr, &dest_ip, 4);
642
643 return skb;
644
645 out:
646 kfree_skb(skb);
647 return NULL;
648 }
649 EXPORT_SYMBOL(arp_create);
650
arp_xmit_finish(struct net * net,struct sock * sk,struct sk_buff * skb)651 static int arp_xmit_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
652 {
653 return dev_queue_xmit(skb);
654 }
655
656 /*
657 * Send an arp packet.
658 */
arp_xmit(struct sk_buff * skb)659 void arp_xmit(struct sk_buff *skb)
660 {
661 rcu_read_lock();
662 /* Send it off, maybe filter it using firewalling first. */
663 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT,
664 dev_net_rcu(skb->dev), NULL, skb, NULL, skb->dev,
665 arp_xmit_finish);
666 rcu_read_unlock();
667 }
668 EXPORT_SYMBOL(arp_xmit);
669
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)670 static bool arp_is_garp(struct net *net, struct net_device *dev,
671 int *addr_type, __be16 ar_op,
672 __be32 sip, __be32 tip,
673 unsigned char *sha, unsigned char *tha)
674 {
675 bool is_garp = tip == sip;
676
677 /* Gratuitous ARP _replies_ also require target hwaddr to be
678 * the same as source.
679 */
680 if (is_garp && ar_op == htons(ARPOP_REPLY))
681 is_garp =
682 /* IPv4 over IEEE 1394 doesn't provide target
683 * hardware address field in its ARP payload.
684 */
685 tha &&
686 !memcmp(tha, sha, dev->addr_len);
687
688 if (is_garp) {
689 *addr_type = inet_addr_type_dev_table(net, dev, sip);
690 if (*addr_type != RTN_UNICAST)
691 is_garp = false;
692 }
693 return is_garp;
694 }
695
696 /*
697 * Process an arp request.
698 */
699
arp_process(struct net * net,struct sock * sk,struct sk_buff * skb)700 static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb)
701 {
702 struct net_device *dev = skb->dev;
703 struct in_device *in_dev = __in_dev_get_rcu(dev);
704 struct arphdr *arp;
705 unsigned char *arp_ptr;
706 struct rtable *rt;
707 unsigned char *sha;
708 unsigned char *tha = NULL;
709 __be32 sip, tip;
710 u16 dev_type = dev->type;
711 int addr_type;
712 struct neighbour *n;
713 struct dst_entry *reply_dst = NULL;
714 bool is_garp = false;
715
716 /* arp_rcv below verifies the ARP header and verifies the device
717 * is ARP'able.
718 */
719
720 if (!in_dev)
721 goto out_free_skb;
722
723 arp = arp_hdr(skb);
724
725 switch (dev_type) {
726 default:
727 if (arp->ar_pro != htons(ETH_P_IP) ||
728 htons(dev_type) != arp->ar_hrd)
729 goto out_free_skb;
730 break;
731 case ARPHRD_ETHER:
732 case ARPHRD_FDDI:
733 case ARPHRD_IEEE802:
734 /*
735 * ETHERNET, and Fibre Channel (which are IEEE 802
736 * devices, according to RFC 2625) devices will accept ARP
737 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
738 * This is the case also of FDDI, where the RFC 1390 says that
739 * FDDI devices should accept ARP hardware of (1) Ethernet,
740 * however, to be more robust, we'll accept both 1 (Ethernet)
741 * or 6 (IEEE 802.2)
742 */
743 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
744 arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
745 arp->ar_pro != htons(ETH_P_IP))
746 goto out_free_skb;
747 break;
748 case ARPHRD_AX25:
749 if (arp->ar_pro != htons(AX25_P_IP) ||
750 arp->ar_hrd != htons(ARPHRD_AX25))
751 goto out_free_skb;
752 break;
753 case ARPHRD_NETROM:
754 if (arp->ar_pro != htons(AX25_P_IP) ||
755 arp->ar_hrd != htons(ARPHRD_NETROM))
756 goto out_free_skb;
757 break;
758 }
759
760 /* Understand only these message types */
761
762 if (arp->ar_op != htons(ARPOP_REPLY) &&
763 arp->ar_op != htons(ARPOP_REQUEST))
764 goto out_free_skb;
765
766 /*
767 * Extract fields
768 */
769 arp_ptr = (unsigned char *)(arp + 1);
770 sha = arp_ptr;
771 arp_ptr += dev->addr_len;
772 memcpy(&sip, arp_ptr, 4);
773 arp_ptr += 4;
774 switch (dev_type) {
775 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
776 case ARPHRD_IEEE1394:
777 break;
778 #endif
779 default:
780 tha = arp_ptr;
781 arp_ptr += dev->addr_len;
782 }
783 memcpy(&tip, arp_ptr, 4);
784 /*
785 * Check for bad requests for 127.x.x.x and requests for multicast
786 * addresses. If this is one such, delete it.
787 */
788 if (ipv4_is_multicast(tip) ||
789 (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip)))
790 goto out_free_skb;
791
792 /*
793 * For some 802.11 wireless deployments (and possibly other networks),
794 * there will be an ARP proxy and gratuitous ARP frames are attacks
795 * and thus should not be accepted.
796 */
797 if (sip == tip && IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP))
798 goto out_free_skb;
799
800 /*
801 * Special case: We must set Frame Relay source Q.922 address
802 */
803 if (dev_type == ARPHRD_DLCI)
804 sha = dev->broadcast;
805
806 /*
807 * Process entry. The idea here is we want to send a reply if it is a
808 * request for us or if it is a request for someone else that we hold
809 * a proxy for. We want to add an entry to our cache if it is a reply
810 * to us or if it is a request for our address.
811 * (The assumption for this last is that if someone is requesting our
812 * address, they are probably intending to talk to us, so it saves time
813 * if we cache their address. Their address is also probably not in
814 * our cache, since ours is not in their cache.)
815 *
816 * Putting this another way, we only care about replies if they are to
817 * us, in which case we add them to the cache. For requests, we care
818 * about those for us and those for our proxies. We reply to both,
819 * and in the case of requests for us we add the requester to the arp
820 * cache.
821 */
822
823 if (arp->ar_op == htons(ARPOP_REQUEST) && skb_metadata_dst(skb))
824 reply_dst = (struct dst_entry *)
825 iptunnel_metadata_reply(skb_metadata_dst(skb),
826 GFP_ATOMIC);
827
828 /* Special case: IPv4 duplicate address detection packet (RFC2131) */
829 if (sip == 0) {
830 if (arp->ar_op == htons(ARPOP_REQUEST) &&
831 inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL &&
832 !arp_ignore(in_dev, sip, tip))
833 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip,
834 sha, dev->dev_addr, sha, reply_dst);
835 goto out_consume_skb;
836 }
837
838 if (arp->ar_op == htons(ARPOP_REQUEST) &&
839 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
840
841 rt = skb_rtable(skb);
842 addr_type = rt->rt_type;
843
844 if (addr_type == RTN_LOCAL) {
845 int dont_send;
846
847 dont_send = arp_ignore(in_dev, sip, tip);
848 if (!dont_send && IN_DEV_ARPFILTER(in_dev))
849 dont_send = arp_filter(sip, tip, dev);
850 if (!dont_send) {
851 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
852 if (n) {
853 arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
854 sip, dev, tip, sha,
855 dev->dev_addr, sha,
856 reply_dst);
857 neigh_release(n);
858 }
859 }
860 goto out_consume_skb;
861 } else if (IN_DEV_FORWARD(in_dev)) {
862 if (addr_type == RTN_UNICAST &&
863 (arp_fwd_proxy(in_dev, dev, rt) ||
864 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
865 (rt->dst.dev != dev &&
866 pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
867 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
868 if (n)
869 neigh_release(n);
870
871 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
872 skb->pkt_type == PACKET_HOST ||
873 NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) {
874 arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
875 sip, dev, tip, sha,
876 dev->dev_addr, sha,
877 reply_dst);
878 } else {
879 pneigh_enqueue(&arp_tbl,
880 in_dev->arp_parms, skb);
881 goto out_free_dst;
882 }
883 goto out_consume_skb;
884 }
885 }
886 }
887
888 /* Update our ARP tables */
889
890 n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
891
892 addr_type = -1;
893 if (n || arp_accept(in_dev, sip)) {
894 is_garp = arp_is_garp(net, dev, &addr_type, arp->ar_op,
895 sip, tip, sha, tha);
896 }
897
898 if (arp_accept(in_dev, sip)) {
899 /* Unsolicited ARP is not accepted by default.
900 It is possible, that this option should be enabled for some
901 devices (strip is candidate)
902 */
903 if (!n &&
904 (is_garp ||
905 (arp->ar_op == htons(ARPOP_REPLY) &&
906 (addr_type == RTN_UNICAST ||
907 (addr_type < 0 &&
908 /* postpone calculation to as late as possible */
909 inet_addr_type_dev_table(net, dev, sip) ==
910 RTN_UNICAST)))))
911 n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
912 }
913
914 if (n) {
915 int state = NUD_REACHABLE;
916 int override;
917
918 /* If several different ARP replies follows back-to-back,
919 use the FIRST one. It is possible, if several proxy
920 agents are active. Taking the first reply prevents
921 arp trashing and chooses the fastest router.
922 */
923 override = time_after(jiffies,
924 n->updated +
925 NEIGH_VAR(n->parms, LOCKTIME)) ||
926 is_garp;
927
928 /* Broadcast replies and request packets
929 do not assert neighbour reachability.
930 */
931 if (arp->ar_op != htons(ARPOP_REPLY) ||
932 skb->pkt_type != PACKET_HOST)
933 state = NUD_STALE;
934 neigh_update(n, sha, state,
935 override ? NEIGH_UPDATE_F_OVERRIDE : 0, 0);
936 neigh_release(n);
937 }
938
939 out_consume_skb:
940 consume_skb(skb);
941
942 out_free_dst:
943 dst_release(reply_dst);
944 return NET_RX_SUCCESS;
945
946 out_free_skb:
947 kfree_skb(skb);
948 return NET_RX_DROP;
949 }
950
parp_redo(struct sk_buff * skb)951 static void parp_redo(struct sk_buff *skb)
952 {
953 arp_process(dev_net(skb->dev), NULL, skb);
954 }
955
arp_is_multicast(const void * pkey)956 static int arp_is_multicast(const void *pkey)
957 {
958 return ipv4_is_multicast(*((__be32 *)pkey));
959 }
960
961 /*
962 * Receive an arp request from the device layer.
963 */
964
arp_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt,struct net_device * orig_dev)965 static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
966 struct packet_type *pt, struct net_device *orig_dev)
967 {
968 const struct arphdr *arp;
969
970 /* do not tweak dropwatch on an ARP we will ignore */
971 if (dev->flags & IFF_NOARP ||
972 skb->pkt_type == PACKET_OTHERHOST ||
973 skb->pkt_type == PACKET_LOOPBACK)
974 goto consumeskb;
975
976 skb = skb_share_check(skb, GFP_ATOMIC);
977 if (!skb)
978 goto out_of_mem;
979
980 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */
981 if (!pskb_may_pull(skb, arp_hdr_len(dev)))
982 goto freeskb;
983
984 arp = arp_hdr(skb);
985 if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4)
986 goto freeskb;
987
988 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
989
990 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN,
991 dev_net(dev), NULL, skb, dev, NULL,
992 arp_process);
993
994 consumeskb:
995 consume_skb(skb);
996 return NET_RX_SUCCESS;
997 freeskb:
998 kfree_skb(skb);
999 out_of_mem:
1000 return NET_RX_DROP;
1001 }
1002
1003 /*
1004 * User level interface (ioctl)
1005 */
1006
1007 /*
1008 * Set (create) an ARP cache entry.
1009 */
1010
arp_req_set_proxy(struct net * net,struct net_device * dev,int on)1011 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
1012 {
1013 if (!dev) {
1014 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
1015 return 0;
1016 }
1017 if (__in_dev_get_rtnl(dev)) {
1018 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
1019 return 0;
1020 }
1021 return -ENXIO;
1022 }
1023
arp_req_set_public(struct net * net,struct arpreq * r,struct net_device * dev)1024 static int arp_req_set_public(struct net *net, struct arpreq *r,
1025 struct net_device *dev)
1026 {
1027 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1028 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1029
1030 if (mask && mask != htonl(0xFFFFFFFF))
1031 return -EINVAL;
1032 if (!dev && (r->arp_flags & ATF_COM)) {
1033 dev = dev_getbyhwaddr(net, r->arp_ha.sa_family,
1034 r->arp_ha.sa_data);
1035 if (!dev)
1036 return -ENODEV;
1037 }
1038 if (mask) {
1039 if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1))
1040 return -ENOBUFS;
1041 return 0;
1042 }
1043
1044 return arp_req_set_proxy(net, dev, 1);
1045 }
1046
arp_req_set(struct net * net,struct arpreq * r,struct net_device * dev)1047 static int arp_req_set(struct net *net, struct arpreq *r,
1048 struct net_device *dev)
1049 {
1050 __be32 ip;
1051 struct neighbour *neigh;
1052 int err;
1053
1054 if (r->arp_flags & ATF_PUBL)
1055 return arp_req_set_public(net, r, dev);
1056
1057 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1058 if (r->arp_flags & ATF_PERM)
1059 r->arp_flags |= ATF_COM;
1060 if (!dev) {
1061 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1062
1063 if (IS_ERR(rt))
1064 return PTR_ERR(rt);
1065 dev = rt->dst.dev;
1066 ip_rt_put(rt);
1067 if (!dev)
1068 return -EINVAL;
1069 }
1070 switch (dev->type) {
1071 #if IS_ENABLED(CONFIG_FDDI)
1072 case ARPHRD_FDDI:
1073 /*
1074 * According to RFC 1390, FDDI devices should accept ARP
1075 * hardware types of 1 (Ethernet). However, to be more
1076 * robust, we'll accept hardware types of either 1 (Ethernet)
1077 * or 6 (IEEE 802.2).
1078 */
1079 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1080 r->arp_ha.sa_family != ARPHRD_ETHER &&
1081 r->arp_ha.sa_family != ARPHRD_IEEE802)
1082 return -EINVAL;
1083 break;
1084 #endif
1085 default:
1086 if (r->arp_ha.sa_family != dev->type)
1087 return -EINVAL;
1088 break;
1089 }
1090
1091 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1092 err = PTR_ERR(neigh);
1093 if (!IS_ERR(neigh)) {
1094 unsigned int state = NUD_STALE;
1095 if (r->arp_flags & ATF_PERM)
1096 state = NUD_PERMANENT;
1097 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ?
1098 r->arp_ha.sa_data : NULL, state,
1099 NEIGH_UPDATE_F_OVERRIDE |
1100 NEIGH_UPDATE_F_ADMIN, 0);
1101 neigh_release(neigh);
1102 }
1103 return err;
1104 }
1105
arp_state_to_flags(struct neighbour * neigh)1106 static unsigned int arp_state_to_flags(struct neighbour *neigh)
1107 {
1108 if (neigh->nud_state&NUD_PERMANENT)
1109 return ATF_PERM | ATF_COM;
1110 else if (neigh->nud_state&NUD_VALID)
1111 return ATF_COM;
1112 else
1113 return 0;
1114 }
1115
1116 /*
1117 * Get an ARP cache entry.
1118 */
1119
arp_req_get(struct arpreq * r,struct net_device * dev)1120 static int arp_req_get(struct arpreq *r, struct net_device *dev)
1121 {
1122 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1123 struct neighbour *neigh;
1124 int err = -ENXIO;
1125
1126 neigh = neigh_lookup(&arp_tbl, &ip, dev);
1127 if (neigh) {
1128 if (!(READ_ONCE(neigh->nud_state) & NUD_NOARP)) {
1129 read_lock_bh(&neigh->lock);
1130 memcpy(r->arp_ha.sa_data, neigh->ha,
1131 min(dev->addr_len, sizeof(r->arp_ha.sa_data_min)));
1132 r->arp_flags = arp_state_to_flags(neigh);
1133 read_unlock_bh(&neigh->lock);
1134 r->arp_ha.sa_family = dev->type;
1135 strscpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1136 err = 0;
1137 }
1138 neigh_release(neigh);
1139 }
1140 return err;
1141 }
1142
arp_invalidate(struct net_device * dev,__be32 ip,bool force)1143 int arp_invalidate(struct net_device *dev, __be32 ip, bool force)
1144 {
1145 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
1146 int err = -ENXIO;
1147 struct neigh_table *tbl = &arp_tbl;
1148
1149 if (neigh) {
1150 if ((READ_ONCE(neigh->nud_state) & NUD_VALID) && !force) {
1151 neigh_release(neigh);
1152 return 0;
1153 }
1154
1155 if (READ_ONCE(neigh->nud_state) & ~NUD_NOARP)
1156 err = neigh_update(neigh, NULL, NUD_FAILED,
1157 NEIGH_UPDATE_F_OVERRIDE|
1158 NEIGH_UPDATE_F_ADMIN, 0);
1159 write_lock_bh(&tbl->lock);
1160 neigh_release(neigh);
1161 neigh_remove_one(neigh, tbl);
1162 write_unlock_bh(&tbl->lock);
1163 }
1164
1165 return err;
1166 }
1167
arp_req_delete_public(struct net * net,struct arpreq * r,struct net_device * dev)1168 static int arp_req_delete_public(struct net *net, struct arpreq *r,
1169 struct net_device *dev)
1170 {
1171 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1172 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1173
1174 if (mask == htonl(0xFFFFFFFF))
1175 return pneigh_delete(&arp_tbl, net, &ip, dev);
1176
1177 if (mask)
1178 return -EINVAL;
1179
1180 return arp_req_set_proxy(net, dev, 0);
1181 }
1182
arp_req_delete(struct net * net,struct arpreq * r,struct net_device * dev)1183 static int arp_req_delete(struct net *net, struct arpreq *r,
1184 struct net_device *dev)
1185 {
1186 __be32 ip;
1187
1188 if (r->arp_flags & ATF_PUBL)
1189 return arp_req_delete_public(net, r, dev);
1190
1191 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1192 if (!dev) {
1193 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1194 if (IS_ERR(rt))
1195 return PTR_ERR(rt);
1196 dev = rt->dst.dev;
1197 ip_rt_put(rt);
1198 if (!dev)
1199 return -EINVAL;
1200 }
1201 return arp_invalidate(dev, ip, true);
1202 }
1203
1204 /*
1205 * Handle an ARP layer I/O control request.
1206 */
1207
arp_ioctl(struct net * net,unsigned int cmd,void __user * arg)1208 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1209 {
1210 int err;
1211 struct arpreq r;
1212 struct net_device *dev = NULL;
1213
1214 switch (cmd) {
1215 case SIOCDARP:
1216 case SIOCSARP:
1217 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1218 return -EPERM;
1219 fallthrough;
1220 case SIOCGARP:
1221 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1222 if (err)
1223 return -EFAULT;
1224 break;
1225 default:
1226 return -EINVAL;
1227 }
1228
1229 if (r.arp_pa.sa_family != AF_INET)
1230 return -EPFNOSUPPORT;
1231
1232 if (!(r.arp_flags & ATF_PUBL) &&
1233 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1234 return -EINVAL;
1235 if (!(r.arp_flags & ATF_NETMASK))
1236 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1237 htonl(0xFFFFFFFFUL);
1238 rtnl_lock();
1239 if (r.arp_dev[0]) {
1240 err = -ENODEV;
1241 dev = __dev_get_by_name(net, r.arp_dev);
1242 if (!dev)
1243 goto out;
1244
1245 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1246 if (!r.arp_ha.sa_family)
1247 r.arp_ha.sa_family = dev->type;
1248 err = -EINVAL;
1249 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1250 goto out;
1251 } else if (cmd == SIOCGARP) {
1252 err = -ENODEV;
1253 goto out;
1254 }
1255
1256 switch (cmd) {
1257 case SIOCDARP:
1258 err = arp_req_delete(net, &r, dev);
1259 break;
1260 case SIOCSARP:
1261 err = arp_req_set(net, &r, dev);
1262 break;
1263 case SIOCGARP:
1264 err = arp_req_get(&r, dev);
1265 break;
1266 }
1267 out:
1268 rtnl_unlock();
1269 if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
1270 err = -EFAULT;
1271 return err;
1272 }
1273
arp_netdev_event(struct notifier_block * this,unsigned long event,void * ptr)1274 static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1275 void *ptr)
1276 {
1277 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
1278 struct netdev_notifier_change_info *change_info;
1279 struct in_device *in_dev;
1280 bool evict_nocarrier;
1281
1282 switch (event) {
1283 case NETDEV_CHANGEADDR:
1284 neigh_changeaddr(&arp_tbl, dev);
1285 rt_cache_flush(dev_net(dev));
1286 break;
1287 case NETDEV_CHANGE:
1288 change_info = ptr;
1289 if (change_info->flags_changed & IFF_NOARP)
1290 neigh_changeaddr(&arp_tbl, dev);
1291
1292 in_dev = __in_dev_get_rtnl(dev);
1293 if (!in_dev)
1294 evict_nocarrier = true;
1295 else
1296 evict_nocarrier = IN_DEV_ARP_EVICT_NOCARRIER(in_dev);
1297
1298 if (evict_nocarrier && !netif_carrier_ok(dev))
1299 neigh_carrier_down(&arp_tbl, dev);
1300 break;
1301 default:
1302 break;
1303 }
1304
1305 return NOTIFY_DONE;
1306 }
1307
1308 static struct notifier_block arp_netdev_notifier = {
1309 .notifier_call = arp_netdev_event,
1310 };
1311
1312 /* Note, that it is not on notifier chain.
1313 It is necessary, that this routine was called after route cache will be
1314 flushed.
1315 */
arp_ifdown(struct net_device * dev)1316 void arp_ifdown(struct net_device *dev)
1317 {
1318 neigh_ifdown(&arp_tbl, dev);
1319 }
1320
1321
1322 /*
1323 * Called once on startup.
1324 */
1325
1326 static struct packet_type arp_packet_type __read_mostly = {
1327 .type = cpu_to_be16(ETH_P_ARP),
1328 .func = arp_rcv,
1329 };
1330
1331 #ifdef CONFIG_PROC_FS
1332 #if IS_ENABLED(CONFIG_AX25)
1333
1334 /*
1335 * ax25 -> ASCII conversion
1336 */
ax2asc2(ax25_address * a,char * buf)1337 static void ax2asc2(ax25_address *a, char *buf)
1338 {
1339 char c, *s;
1340 int n;
1341
1342 for (n = 0, s = buf; n < 6; n++) {
1343 c = (a->ax25_call[n] >> 1) & 0x7F;
1344
1345 if (c != ' ')
1346 *s++ = c;
1347 }
1348
1349 *s++ = '-';
1350 n = (a->ax25_call[6] >> 1) & 0x0F;
1351 if (n > 9) {
1352 *s++ = '1';
1353 n -= 10;
1354 }
1355
1356 *s++ = n + '0';
1357 *s++ = '\0';
1358
1359 if (*buf == '\0' || *buf == '-') {
1360 buf[0] = '*';
1361 buf[1] = '\0';
1362 }
1363 }
1364 #endif /* CONFIG_AX25 */
1365
1366 #define HBUFFERLEN 30
1367
arp_format_neigh_entry(struct seq_file * seq,struct neighbour * n)1368 static void arp_format_neigh_entry(struct seq_file *seq,
1369 struct neighbour *n)
1370 {
1371 char hbuffer[HBUFFERLEN];
1372 int k, j;
1373 char tbuf[16];
1374 struct net_device *dev = n->dev;
1375 int hatype = dev->type;
1376
1377 read_lock(&n->lock);
1378 /* Convert hardware address to XX:XX:XX:XX ... form. */
1379 #if IS_ENABLED(CONFIG_AX25)
1380 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1381 ax2asc2((ax25_address *)n->ha, hbuffer);
1382 else {
1383 #endif
1384 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1385 hbuffer[k++] = hex_asc_hi(n->ha[j]);
1386 hbuffer[k++] = hex_asc_lo(n->ha[j]);
1387 hbuffer[k++] = ':';
1388 }
1389 if (k != 0)
1390 --k;
1391 hbuffer[k] = 0;
1392 #if IS_ENABLED(CONFIG_AX25)
1393 }
1394 #endif
1395 sprintf(tbuf, "%pI4", n->primary_key);
1396 seq_printf(seq, "%-16s 0x%-10x0x%-10x%-17s * %s\n",
1397 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1398 read_unlock(&n->lock);
1399 }
1400
arp_format_pneigh_entry(struct seq_file * seq,struct pneigh_entry * n)1401 static void arp_format_pneigh_entry(struct seq_file *seq,
1402 struct pneigh_entry *n)
1403 {
1404 struct net_device *dev = n->dev;
1405 int hatype = dev ? dev->type : 0;
1406 char tbuf[16];
1407
1408 sprintf(tbuf, "%pI4", n->key);
1409 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
1410 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1411 dev ? dev->name : "*");
1412 }
1413
arp_seq_show(struct seq_file * seq,void * v)1414 static int arp_seq_show(struct seq_file *seq, void *v)
1415 {
1416 if (v == SEQ_START_TOKEN) {
1417 seq_puts(seq, "IP address HW type Flags "
1418 "HW address Mask Device\n");
1419 } else {
1420 struct neigh_seq_state *state = seq->private;
1421
1422 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1423 arp_format_pneigh_entry(seq, v);
1424 else
1425 arp_format_neigh_entry(seq, v);
1426 }
1427
1428 return 0;
1429 }
1430
arp_seq_start(struct seq_file * seq,loff_t * pos)1431 static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1432 {
1433 /* Don't want to confuse "arp -a" w/ magic entries,
1434 * so we tell the generic iterator to skip NUD_NOARP.
1435 */
1436 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1437 }
1438
1439 static const struct seq_operations arp_seq_ops = {
1440 .start = arp_seq_start,
1441 .next = neigh_seq_next,
1442 .stop = neigh_seq_stop,
1443 .show = arp_seq_show,
1444 };
1445 #endif /* CONFIG_PROC_FS */
1446
arp_net_init(struct net * net)1447 static int __net_init arp_net_init(struct net *net)
1448 {
1449 if (!proc_create_net("arp", 0444, net->proc_net, &arp_seq_ops,
1450 sizeof(struct neigh_seq_state)))
1451 return -ENOMEM;
1452 return 0;
1453 }
1454
arp_net_exit(struct net * net)1455 static void __net_exit arp_net_exit(struct net *net)
1456 {
1457 remove_proc_entry("arp", net->proc_net);
1458 }
1459
1460 static struct pernet_operations arp_net_ops = {
1461 .init = arp_net_init,
1462 .exit = arp_net_exit,
1463 };
1464
arp_init(void)1465 void __init arp_init(void)
1466 {
1467 neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl);
1468
1469 dev_add_pack(&arp_packet_type);
1470 register_pernet_subsys(&arp_net_ops);
1471 #ifdef CONFIG_SYSCTL
1472 neigh_sysctl_register(NULL, &arp_tbl.parms, NULL);
1473 #endif
1474 register_netdevice_notifier(&arp_netdev_notifier);
1475 }
1476