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Linux/net/ipv4/arp.c

  1 /* linux/net/ipv4/arp.c
  2  *
  3  * Copyright (C) 1994 by Florian  La Roche
  4  *
  5  * This module implements the Address Resolution Protocol ARP (RFC 826),
  6  * which is used to convert IP addresses (or in the future maybe other
  7  * high-level addresses) into a low-level hardware address (like an Ethernet
  8  * address).
  9  *
 10  * This program is free software; you can redistribute it and/or
 11  * modify it under the terms of the GNU General Public License
 12  * as published by the Free Software Foundation; either version
 13  * 2 of the License, or (at your option) any later version.
 14  *
 15  * Fixes:
 16  *              Alan Cox        :       Removed the Ethernet assumptions in
 17  *                                      Florian's code
 18  *              Alan Cox        :       Fixed some small errors in the ARP
 19  *                                      logic
 20  *              Alan Cox        :       Allow >4K in /proc
 21  *              Alan Cox        :       Make ARP add its own protocol entry
 22  *              Ross Martin     :       Rewrote arp_rcv() and arp_get_info()
 23  *              Stephen Henson  :       Add AX25 support to arp_get_info()
 24  *              Alan Cox        :       Drop data when a device is downed.
 25  *              Alan Cox        :       Use init_timer().
 26  *              Alan Cox        :       Double lock fixes.
 27  *              Martin Seine    :       Move the arphdr structure
 28  *                                      to if_arp.h for compatibility.
 29  *                                      with BSD based programs.
 30  *              Andrew Tridgell :       Added ARP netmask code and
 31  *                                      re-arranged proxy handling.
 32  *              Alan Cox        :       Changed to use notifiers.
 33  *              Niibe Yutaka    :       Reply for this device or proxies only.
 34  *              Alan Cox        :       Don't proxy across hardware types!
 35  *              Jonathan Naylor :       Added support for NET/ROM.
 36  *              Mike Shaver     :       RFC1122 checks.
 37  *              Jonathan Naylor :       Only lookup the hardware address for
 38  *                                      the correct hardware type.
 39  *              Germano Caronni :       Assorted subtle races.
 40  *              Craig Schlenter :       Don't modify permanent entry
 41  *                                      during arp_rcv.
 42  *              Russ Nelson     :       Tidied up a few bits.
 43  *              Alexey Kuznetsov:       Major changes to caching and behaviour,
 44  *                                      eg intelligent arp probing and
 45  *                                      generation
 46  *                                      of host down events.
 47  *              Alan Cox        :       Missing unlock in device events.
 48  *              Eckes           :       ARP ioctl control errors.
 49  *              Alexey Kuznetsov:       Arp free fix.
 50  *              Manuel Rodriguez:       Gratuitous ARP.
 51  *              Jonathan Layes  :       Added arpd support through kerneld
 52  *                                      message queue (960314)
 53  *              Mike Shaver     :       /proc/sys/net/ipv4/arp_* support
 54  *              Mike McLagan    :       Routing by source
 55  *              Stuart Cheshire :       Metricom and grat arp fixes
 56  *                                      *** FOR 2.1 clean this up ***
 57  *              Lawrence V. Stefani: (08/12/96) Added FDDI support.
 58  *              Alan Cox        :       Took the AP1000 nasty FDDI hack and
 59  *                                      folded into the mainstream FDDI code.
 60  *                                      Ack spit, Linus how did you allow that
 61  *                                      one in...
 62  *              Jes Sorensen    :       Make FDDI work again in 2.1.x and
 63  *                                      clean up the APFDDI & gen. FDDI bits.
 64  *              Alexey Kuznetsov:       new arp state machine;
 65  *                                      now it is in net/core/neighbour.c.
 66  *              Krzysztof Halasa:       Added Frame Relay ARP support.
 67  *              Arnaldo C. Melo :       convert /proc/net/arp to seq_file
 68  *              Shmulik Hen:            Split arp_send to arp_create and
 69  *                                      arp_xmit so intermediate drivers like
 70  *                                      bonding can change the skb before
 71  *                                      sending (e.g. insert 8021q tag).
 72  *              Harald Welte    :       convert to make use of jenkins hash
 73  *              Jesper D. Brouer:       Proxy ARP PVLAN RFC 3069 support.
 74  */
 75 
 76 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 77 
 78 #include <linux/module.h>
 79 #include <linux/types.h>
 80 #include <linux/string.h>
 81 #include <linux/kernel.h>
 82 #include <linux/capability.h>
 83 #include <linux/socket.h>
 84 #include <linux/sockios.h>
 85 #include <linux/errno.h>
 86 #include <linux/in.h>
 87 #include <linux/mm.h>
 88 #include <linux/inet.h>
 89 #include <linux/inetdevice.h>
 90 #include <linux/netdevice.h>
 91 #include <linux/etherdevice.h>
 92 #include <linux/fddidevice.h>
 93 #include <linux/if_arp.h>
 94 #include <linux/skbuff.h>
 95 #include <linux/proc_fs.h>
 96 #include <linux/seq_file.h>
 97 #include <linux/stat.h>
 98 #include <linux/init.h>
 99 #include <linux/net.h>
100 #include <linux/rcupdate.h>
101 #include <linux/slab.h>
102 #ifdef CONFIG_SYSCTL
103 #include <linux/sysctl.h>
104 #endif
105 
106 #include <net/net_namespace.h>
107 #include <net/ip.h>
108 #include <net/icmp.h>
109 #include <net/route.h>
110 #include <net/protocol.h>
111 #include <net/tcp.h>
112 #include <net/sock.h>
113 #include <net/arp.h>
114 #include <net/ax25.h>
115 #include <net/netrom.h>
116 
117 #include <linux/uaccess.h>
118 
119 #include <linux/netfilter_arp.h>
120 
121 /*
122  *      Interface to generic neighbour cache.
123  */
124 static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd);
125 static bool arp_key_eq(const struct neighbour *n, const void *pkey);
126 static int arp_constructor(struct neighbour *neigh);
127 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
128 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
129 static void parp_redo(struct sk_buff *skb);
130 
131 static const struct neigh_ops arp_generic_ops = {
132         .family =               AF_INET,
133         .solicit =              arp_solicit,
134         .error_report =         arp_error_report,
135         .output =               neigh_resolve_output,
136         .connected_output =     neigh_connected_output,
137 };
138 
139 static const struct neigh_ops arp_hh_ops = {
140         .family =               AF_INET,
141         .solicit =              arp_solicit,
142         .error_report =         arp_error_report,
143         .output =               neigh_resolve_output,
144         .connected_output =     neigh_resolve_output,
145 };
146 
147 static const struct neigh_ops arp_direct_ops = {
148         .family =               AF_INET,
149         .output =               neigh_direct_output,
150         .connected_output =     neigh_direct_output,
151 };
152 
153 struct neigh_table arp_tbl = {
154         .family         = AF_INET,
155         .key_len        = 4,
156         .protocol       = cpu_to_be16(ETH_P_IP),
157         .hash           = arp_hash,
158         .key_eq         = arp_key_eq,
159         .constructor    = arp_constructor,
160         .proxy_redo     = parp_redo,
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] = 64 * 1024,
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 
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 
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 
217 static bool arp_key_eq(const struct neighbour *neigh, const void *pkey)
218 {
219         return neigh_key_eq32(neigh, pkey);
220 }
221 
222 static int arp_constructor(struct neighbour *neigh)
223 {
224         __be32 addr = *(__be32 *)neigh->primary_key;
225         struct net_device *dev = neigh->dev;
226         struct in_device *in_dev;
227         struct neigh_parms *parms;
228 
229         rcu_read_lock();
230         in_dev = __in_dev_get_rcu(dev);
231         if (!in_dev) {
232                 rcu_read_unlock();
233                 return -EINVAL;
234         }
235 
236         neigh->type = inet_addr_type(dev_net(dev), addr);
237 
238         parms = in_dev->arp_parms;
239         __neigh_parms_put(neigh->parms);
240         neigh->parms = neigh_parms_clone(parms);
241         rcu_read_unlock();
242 
243         if (!dev->header_ops) {
244                 neigh->nud_state = NUD_NOARP;
245                 neigh->ops = &arp_direct_ops;
246                 neigh->output = neigh_direct_output;
247         } else {
248                 /* Good devices (checked by reading texts, but only Ethernet is
249                    tested)
250 
251                    ARPHRD_ETHER: (ethernet, apfddi)
252                    ARPHRD_FDDI: (fddi)
253                    ARPHRD_IEEE802: (tr)
254                    ARPHRD_METRICOM: (strip)
255                    ARPHRD_ARCNET:
256                    etc. etc. etc.
257 
258                    ARPHRD_IPDDP will also work, if author repairs it.
259                    I did not it, because this driver does not work even
260                    in old paradigm.
261                  */
262 
263                 if (neigh->type == RTN_MULTICAST) {
264                         neigh->nud_state = NUD_NOARP;
265                         arp_mc_map(addr, neigh->ha, dev, 1);
266                 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) {
267                         neigh->nud_state = NUD_NOARP;
268                         memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
269                 } else if (neigh->type == RTN_BROADCAST ||
270                            (dev->flags & IFF_POINTOPOINT)) {
271                         neigh->nud_state = NUD_NOARP;
272                         memcpy(neigh->ha, dev->broadcast, dev->addr_len);
273                 }
274 
275                 if (dev->header_ops->cache)
276                         neigh->ops = &arp_hh_ops;
277                 else
278                         neigh->ops = &arp_generic_ops;
279 
280                 if (neigh->nud_state & NUD_VALID)
281                         neigh->output = neigh->ops->connected_output;
282                 else
283                         neigh->output = neigh->ops->output;
284         }
285         return 0;
286 }
287 
288 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
289 {
290         dst_link_failure(skb);
291         kfree_skb(skb);
292 }
293 
294 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
295 {
296         __be32 saddr = 0;
297         u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL;
298         struct net_device *dev = neigh->dev;
299         __be32 target = *(__be32 *)neigh->primary_key;
300         int probes = atomic_read(&neigh->probes);
301         struct in_device *in_dev;
302 
303         rcu_read_lock();
304         in_dev = __in_dev_get_rcu(dev);
305         if (!in_dev) {
306                 rcu_read_unlock();
307                 return;
308         }
309         switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
310         default:
311         case 0:         /* By default announce any local IP */
312                 if (skb && inet_addr_type(dev_net(dev),
313                                           ip_hdr(skb)->saddr) == RTN_LOCAL)
314                         saddr = ip_hdr(skb)->saddr;
315                 break;
316         case 1:         /* Restrict announcements of saddr in same subnet */
317                 if (!skb)
318                         break;
319                 saddr = ip_hdr(skb)->saddr;
320                 if (inet_addr_type(dev_net(dev), saddr) == RTN_LOCAL) {
321                         /* saddr should be known to target */
322                         if (inet_addr_onlink(in_dev, target, saddr))
323                                 break;
324                 }
325                 saddr = 0;
326                 break;
327         case 2:         /* Avoid secondary IPs, get a primary/preferred one */
328                 break;
329         }
330         rcu_read_unlock();
331 
332         if (!saddr)
333                 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
334 
335         probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES);
336         if (probes < 0) {
337                 if (!(neigh->nud_state & NUD_VALID))
338                         pr_debug("trying to ucast probe in NUD_INVALID\n");
339                 neigh_ha_snapshot(dst_ha, neigh, dev);
340                 dst_hw = dst_ha;
341         } else {
342                 probes -= NEIGH_VAR(neigh->parms, APP_PROBES);
343                 if (probes < 0) {
344                         neigh_app_ns(neigh);
345                         return;
346                 }
347         }
348 
349         arp_send(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
350                  dst_hw, dev->dev_addr, NULL);
351 }
352 
353 static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip)
354 {
355         struct net *net = dev_net(in_dev->dev);
356         int scope;
357 
358         switch (IN_DEV_ARP_IGNORE(in_dev)) {
359         case 0: /* Reply, the tip is already validated */
360                 return 0;
361         case 1: /* Reply only if tip is configured on the incoming interface */
362                 sip = 0;
363                 scope = RT_SCOPE_HOST;
364                 break;
365         case 2: /*
366                  * Reply only if tip is configured on the incoming interface
367                  * and is in same subnet as sip
368                  */
369                 scope = RT_SCOPE_HOST;
370                 break;
371         case 3: /* Do not reply for scope host addresses */
372                 sip = 0;
373                 scope = RT_SCOPE_LINK;
374                 in_dev = NULL;
375                 break;
376         case 4: /* Reserved */
377         case 5:
378         case 6:
379         case 7:
380                 return 0;
381         case 8: /* Do not reply */
382                 return 1;
383         default:
384                 return 0;
385         }
386         return !inet_confirm_addr(net, in_dev, sip, tip, scope);
387 }
388 
389 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
390 {
391         struct rtable *rt;
392         int flag = 0;
393         /*unsigned long now; */
394         struct net *net = dev_net(dev);
395 
396         rt = ip_route_output(net, sip, tip, 0, 0);
397         if (IS_ERR(rt))
398                 return 1;
399         if (rt->dst.dev != dev) {
400                 NET_INC_STATS_BH(net, LINUX_MIB_ARPFILTER);
401                 flag = 1;
402         }
403         ip_rt_put(rt);
404         return flag;
405 }
406 
407 /*
408  * Check if we can use proxy ARP for this path
409  */
410 static inline int arp_fwd_proxy(struct in_device *in_dev,
411                                 struct net_device *dev, struct rtable *rt)
412 {
413         struct in_device *out_dev;
414         int imi, omi = -1;
415 
416         if (rt->dst.dev == dev)
417                 return 0;
418 
419         if (!IN_DEV_PROXY_ARP(in_dev))
420                 return 0;
421         imi = IN_DEV_MEDIUM_ID(in_dev);
422         if (imi == 0)
423                 return 1;
424         if (imi == -1)
425                 return 0;
426 
427         /* place to check for proxy_arp for routes */
428 
429         out_dev = __in_dev_get_rcu(rt->dst.dev);
430         if (out_dev)
431                 omi = IN_DEV_MEDIUM_ID(out_dev);
432 
433         return omi != imi && omi != -1;
434 }
435 
436 /*
437  * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
438  *
439  * RFC3069 supports proxy arp replies back to the same interface.  This
440  * is done to support (ethernet) switch features, like RFC 3069, where
441  * the individual ports are not allowed to communicate with each
442  * other, BUT they are allowed to talk to the upstream router.  As
443  * described in RFC 3069, it is possible to allow these hosts to
444  * communicate through the upstream router, by proxy_arp'ing.
445  *
446  * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
447  *
448  *  This technology is known by different names:
449  *    In RFC 3069 it is called VLAN Aggregation.
450  *    Cisco and Allied Telesyn call it Private VLAN.
451  *    Hewlett-Packard call it Source-Port filtering or port-isolation.
452  *    Ericsson call it MAC-Forced Forwarding (RFC Draft).
453  *
454  */
455 static inline int arp_fwd_pvlan(struct in_device *in_dev,
456                                 struct net_device *dev, struct rtable *rt,
457                                 __be32 sip, __be32 tip)
458 {
459         /* Private VLAN is only concerned about the same ethernet segment */
460         if (rt->dst.dev != dev)
461                 return 0;
462 
463         /* Don't reply on self probes (often done by windowz boxes)*/
464         if (sip == tip)
465                 return 0;
466 
467         if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
468                 return 1;
469         else
470                 return 0;
471 }
472 
473 /*
474  *      Interface to link layer: send routine and receive handler.
475  */
476 
477 /*
478  *      Create an arp packet. If dest_hw is not set, we create a broadcast
479  *      message.
480  */
481 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
482                            struct net_device *dev, __be32 src_ip,
483                            const unsigned char *dest_hw,
484                            const unsigned char *src_hw,
485                            const unsigned char *target_hw)
486 {
487         struct sk_buff *skb;
488         struct arphdr *arp;
489         unsigned char *arp_ptr;
490         int hlen = LL_RESERVED_SPACE(dev);
491         int tlen = dev->needed_tailroom;
492 
493         /*
494          *      Allocate a buffer
495          */
496 
497         skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
498         if (!skb)
499                 return NULL;
500 
501         skb_reserve(skb, hlen);
502         skb_reset_network_header(skb);
503         arp = (struct arphdr *) skb_put(skb, arp_hdr_len(dev));
504         skb->dev = dev;
505         skb->protocol = htons(ETH_P_ARP);
506         if (!src_hw)
507                 src_hw = dev->dev_addr;
508         if (!dest_hw)
509                 dest_hw = dev->broadcast;
510 
511         /*
512          *      Fill the device header for the ARP frame
513          */
514         if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
515                 goto out;
516 
517         /*
518          * Fill out the arp protocol part.
519          *
520          * The arp hardware type should match the device type, except for FDDI,
521          * which (according to RFC 1390) should always equal 1 (Ethernet).
522          */
523         /*
524          *      Exceptions everywhere. AX.25 uses the AX.25 PID value not the
525          *      DIX code for the protocol. Make these device structure fields.
526          */
527         switch (dev->type) {
528         default:
529                 arp->ar_hrd = htons(dev->type);
530                 arp->ar_pro = htons(ETH_P_IP);
531                 break;
532 
533 #if IS_ENABLED(CONFIG_AX25)
534         case ARPHRD_AX25:
535                 arp->ar_hrd = htons(ARPHRD_AX25);
536                 arp->ar_pro = htons(AX25_P_IP);
537                 break;
538 
539 #if IS_ENABLED(CONFIG_NETROM)
540         case ARPHRD_NETROM:
541                 arp->ar_hrd = htons(ARPHRD_NETROM);
542                 arp->ar_pro = htons(AX25_P_IP);
543                 break;
544 #endif
545 #endif
546 
547 #if IS_ENABLED(CONFIG_FDDI)
548         case ARPHRD_FDDI:
549                 arp->ar_hrd = htons(ARPHRD_ETHER);
550                 arp->ar_pro = htons(ETH_P_IP);
551                 break;
552 #endif
553         }
554 
555         arp->ar_hln = dev->addr_len;
556         arp->ar_pln = 4;
557         arp->ar_op = htons(type);
558 
559         arp_ptr = (unsigned char *)(arp + 1);
560 
561         memcpy(arp_ptr, src_hw, dev->addr_len);
562         arp_ptr += dev->addr_len;
563         memcpy(arp_ptr, &src_ip, 4);
564         arp_ptr += 4;
565 
566         switch (dev->type) {
567 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
568         case ARPHRD_IEEE1394:
569                 break;
570 #endif
571         default:
572                 if (target_hw)
573                         memcpy(arp_ptr, target_hw, dev->addr_len);
574                 else
575                         memset(arp_ptr, 0, dev->addr_len);
576                 arp_ptr += dev->addr_len;
577         }
578         memcpy(arp_ptr, &dest_ip, 4);
579 
580         return skb;
581 
582 out:
583         kfree_skb(skb);
584         return NULL;
585 }
586 EXPORT_SYMBOL(arp_create);
587 
588 /*
589  *      Send an arp packet.
590  */
591 void arp_xmit(struct sk_buff *skb)
592 {
593         /* Send it off, maybe filter it using firewalling first.  */
594         NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, NULL, skb,
595                 NULL, skb->dev, dev_queue_xmit_sk);
596 }
597 EXPORT_SYMBOL(arp_xmit);
598 
599 /*
600  *      Create and send an arp packet.
601  */
602 void arp_send(int type, int ptype, __be32 dest_ip,
603               struct net_device *dev, __be32 src_ip,
604               const unsigned char *dest_hw, const unsigned char *src_hw,
605               const unsigned char *target_hw)
606 {
607         struct sk_buff *skb;
608 
609         /*
610          *      No arp on this interface.
611          */
612 
613         if (dev->flags&IFF_NOARP)
614                 return;
615 
616         skb = arp_create(type, ptype, dest_ip, dev, src_ip,
617                          dest_hw, src_hw, target_hw);
618         if (!skb)
619                 return;
620 
621         arp_xmit(skb);
622 }
623 EXPORT_SYMBOL(arp_send);
624 
625 /*
626  *      Process an arp request.
627  */
628 
629 static int arp_process(struct sock *sk, struct sk_buff *skb)
630 {
631         struct net_device *dev = skb->dev;
632         struct in_device *in_dev = __in_dev_get_rcu(dev);
633         struct arphdr *arp;
634         unsigned char *arp_ptr;
635         struct rtable *rt;
636         unsigned char *sha;
637         __be32 sip, tip;
638         u16 dev_type = dev->type;
639         int addr_type;
640         struct neighbour *n;
641         struct net *net = dev_net(dev);
642         bool is_garp = false;
643 
644         /* arp_rcv below verifies the ARP header and verifies the device
645          * is ARP'able.
646          */
647 
648         if (!in_dev)
649                 goto out;
650 
651         arp = arp_hdr(skb);
652 
653         switch (dev_type) {
654         default:
655                 if (arp->ar_pro != htons(ETH_P_IP) ||
656                     htons(dev_type) != arp->ar_hrd)
657                         goto out;
658                 break;
659         case ARPHRD_ETHER:
660         case ARPHRD_FDDI:
661         case ARPHRD_IEEE802:
662                 /*
663                  * ETHERNET, and Fibre Channel (which are IEEE 802
664                  * devices, according to RFC 2625) devices will accept ARP
665                  * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
666                  * This is the case also of FDDI, where the RFC 1390 says that
667                  * FDDI devices should accept ARP hardware of (1) Ethernet,
668                  * however, to be more robust, we'll accept both 1 (Ethernet)
669                  * or 6 (IEEE 802.2)
670                  */
671                 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
672                      arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
673                     arp->ar_pro != htons(ETH_P_IP))
674                         goto out;
675                 break;
676         case ARPHRD_AX25:
677                 if (arp->ar_pro != htons(AX25_P_IP) ||
678                     arp->ar_hrd != htons(ARPHRD_AX25))
679                         goto out;
680                 break;
681         case ARPHRD_NETROM:
682                 if (arp->ar_pro != htons(AX25_P_IP) ||
683                     arp->ar_hrd != htons(ARPHRD_NETROM))
684                         goto out;
685                 break;
686         }
687 
688         /* Understand only these message types */
689 
690         if (arp->ar_op != htons(ARPOP_REPLY) &&
691             arp->ar_op != htons(ARPOP_REQUEST))
692                 goto out;
693 
694 /*
695  *      Extract fields
696  */
697         arp_ptr = (unsigned char *)(arp + 1);
698         sha     = arp_ptr;
699         arp_ptr += dev->addr_len;
700         memcpy(&sip, arp_ptr, 4);
701         arp_ptr += 4;
702         switch (dev_type) {
703 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
704         case ARPHRD_IEEE1394:
705                 break;
706 #endif
707         default:
708                 arp_ptr += dev->addr_len;
709         }
710         memcpy(&tip, arp_ptr, 4);
711 /*
712  *      Check for bad requests for 127.x.x.x and requests for multicast
713  *      addresses.  If this is one such, delete it.
714  */
715         if (ipv4_is_multicast(tip) ||
716             (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip)))
717                 goto out;
718 
719 /*
720  *     Special case: We must set Frame Relay source Q.922 address
721  */
722         if (dev_type == ARPHRD_DLCI)
723                 sha = dev->broadcast;
724 
725 /*
726  *  Process entry.  The idea here is we want to send a reply if it is a
727  *  request for us or if it is a request for someone else that we hold
728  *  a proxy for.  We want to add an entry to our cache if it is a reply
729  *  to us or if it is a request for our address.
730  *  (The assumption for this last is that if someone is requesting our
731  *  address, they are probably intending to talk to us, so it saves time
732  *  if we cache their address.  Their address is also probably not in
733  *  our cache, since ours is not in their cache.)
734  *
735  *  Putting this another way, we only care about replies if they are to
736  *  us, in which case we add them to the cache.  For requests, we care
737  *  about those for us and those for our proxies.  We reply to both,
738  *  and in the case of requests for us we add the requester to the arp
739  *  cache.
740  */
741 
742         /* Special case: IPv4 duplicate address detection packet (RFC2131) */
743         if (sip == 0) {
744                 if (arp->ar_op == htons(ARPOP_REQUEST) &&
745                     inet_addr_type(net, tip) == RTN_LOCAL &&
746                     !arp_ignore(in_dev, sip, tip))
747                         arp_send(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, sha,
748                                  dev->dev_addr, sha);
749                 goto out;
750         }
751 
752         if (arp->ar_op == htons(ARPOP_REQUEST) &&
753             ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
754 
755                 rt = skb_rtable(skb);
756                 addr_type = rt->rt_type;
757 
758                 if (addr_type == RTN_LOCAL) {
759                         int dont_send;
760 
761                         dont_send = arp_ignore(in_dev, sip, tip);
762                         if (!dont_send && IN_DEV_ARPFILTER(in_dev))
763                                 dont_send = arp_filter(sip, tip, dev);
764                         if (!dont_send) {
765                                 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
766                                 if (n) {
767                                         arp_send(ARPOP_REPLY, ETH_P_ARP, sip,
768                                                  dev, tip, sha, dev->dev_addr,
769                                                  sha);
770                                         neigh_release(n);
771                                 }
772                         }
773                         goto out;
774                 } else if (IN_DEV_FORWARD(in_dev)) {
775                         if (addr_type == RTN_UNICAST  &&
776                             (arp_fwd_proxy(in_dev, dev, rt) ||
777                              arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
778                              (rt->dst.dev != dev &&
779                               pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
780                                 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
781                                 if (n)
782                                         neigh_release(n);
783 
784                                 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
785                                     skb->pkt_type == PACKET_HOST ||
786                                     NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) {
787                                         arp_send(ARPOP_REPLY, ETH_P_ARP, sip,
788                                                  dev, tip, sha, dev->dev_addr,
789                                                  sha);
790                                 } else {
791                                         pneigh_enqueue(&arp_tbl,
792                                                        in_dev->arp_parms, skb);
793                                         return 0;
794                                 }
795                                 goto out;
796                         }
797                 }
798         }
799 
800         /* Update our ARP tables */
801 
802         n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
803 
804         if (IN_DEV_ARP_ACCEPT(in_dev)) {
805                 /* Unsolicited ARP is not accepted by default.
806                    It is possible, that this option should be enabled for some
807                    devices (strip is candidate)
808                  */
809                 is_garp = arp->ar_op == htons(ARPOP_REQUEST) && tip == sip &&
810                           inet_addr_type(net, sip) == RTN_UNICAST;
811 
812                 if (!n &&
813                     ((arp->ar_op == htons(ARPOP_REPLY)  &&
814                       inet_addr_type(net, sip) == RTN_UNICAST) || is_garp))
815                         n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
816         }
817 
818         if (n) {
819                 int state = NUD_REACHABLE;
820                 int override;
821 
822                 /* If several different ARP replies follows back-to-back,
823                    use the FIRST one. It is possible, if several proxy
824                    agents are active. Taking the first reply prevents
825                    arp trashing and chooses the fastest router.
826                  */
827                 override = time_after(jiffies,
828                                       n->updated +
829                                       NEIGH_VAR(n->parms, LOCKTIME)) ||
830                            is_garp;
831 
832                 /* Broadcast replies and request packets
833                    do not assert neighbour reachability.
834                  */
835                 if (arp->ar_op != htons(ARPOP_REPLY) ||
836                     skb->pkt_type != PACKET_HOST)
837                         state = NUD_STALE;
838                 neigh_update(n, sha, state,
839                              override ? NEIGH_UPDATE_F_OVERRIDE : 0);
840                 neigh_release(n);
841         }
842 
843 out:
844         consume_skb(skb);
845         return 0;
846 }
847 
848 static void parp_redo(struct sk_buff *skb)
849 {
850         arp_process(NULL, skb);
851 }
852 
853 
854 /*
855  *      Receive an arp request from the device layer.
856  */
857 
858 static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
859                    struct packet_type *pt, struct net_device *orig_dev)
860 {
861         const struct arphdr *arp;
862 
863         /* do not tweak dropwatch on an ARP we will ignore */
864         if (dev->flags & IFF_NOARP ||
865             skb->pkt_type == PACKET_OTHERHOST ||
866             skb->pkt_type == PACKET_LOOPBACK)
867                 goto consumeskb;
868 
869         skb = skb_share_check(skb, GFP_ATOMIC);
870         if (!skb)
871                 goto out_of_mem;
872 
873         /* ARP header, plus 2 device addresses, plus 2 IP addresses.  */
874         if (!pskb_may_pull(skb, arp_hdr_len(dev)))
875                 goto freeskb;
876 
877         arp = arp_hdr(skb);
878         if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4)
879                 goto freeskb;
880 
881         memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
882 
883         return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, NULL, skb,
884                        dev, NULL, arp_process);
885 
886 consumeskb:
887         consume_skb(skb);
888         return 0;
889 freeskb:
890         kfree_skb(skb);
891 out_of_mem:
892         return 0;
893 }
894 
895 /*
896  *      User level interface (ioctl)
897  */
898 
899 /*
900  *      Set (create) an ARP cache entry.
901  */
902 
903 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
904 {
905         if (!dev) {
906                 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
907                 return 0;
908         }
909         if (__in_dev_get_rtnl(dev)) {
910                 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
911                 return 0;
912         }
913         return -ENXIO;
914 }
915 
916 static int arp_req_set_public(struct net *net, struct arpreq *r,
917                 struct net_device *dev)
918 {
919         __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
920         __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
921 
922         if (mask && mask != htonl(0xFFFFFFFF))
923                 return -EINVAL;
924         if (!dev && (r->arp_flags & ATF_COM)) {
925                 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family,
926                                       r->arp_ha.sa_data);
927                 if (!dev)
928                         return -ENODEV;
929         }
930         if (mask) {
931                 if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1))
932                         return -ENOBUFS;
933                 return 0;
934         }
935 
936         return arp_req_set_proxy(net, dev, 1);
937 }
938 
939 static int arp_req_set(struct net *net, struct arpreq *r,
940                        struct net_device *dev)
941 {
942         __be32 ip;
943         struct neighbour *neigh;
944         int err;
945 
946         if (r->arp_flags & ATF_PUBL)
947                 return arp_req_set_public(net, r, dev);
948 
949         ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
950         if (r->arp_flags & ATF_PERM)
951                 r->arp_flags |= ATF_COM;
952         if (!dev) {
953                 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
954 
955                 if (IS_ERR(rt))
956                         return PTR_ERR(rt);
957                 dev = rt->dst.dev;
958                 ip_rt_put(rt);
959                 if (!dev)
960                         return -EINVAL;
961         }
962         switch (dev->type) {
963 #if IS_ENABLED(CONFIG_FDDI)
964         case ARPHRD_FDDI:
965                 /*
966                  * According to RFC 1390, FDDI devices should accept ARP
967                  * hardware types of 1 (Ethernet).  However, to be more
968                  * robust, we'll accept hardware types of either 1 (Ethernet)
969                  * or 6 (IEEE 802.2).
970                  */
971                 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
972                     r->arp_ha.sa_family != ARPHRD_ETHER &&
973                     r->arp_ha.sa_family != ARPHRD_IEEE802)
974                         return -EINVAL;
975                 break;
976 #endif
977         default:
978                 if (r->arp_ha.sa_family != dev->type)
979                         return -EINVAL;
980                 break;
981         }
982 
983         neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
984         err = PTR_ERR(neigh);
985         if (!IS_ERR(neigh)) {
986                 unsigned int state = NUD_STALE;
987                 if (r->arp_flags & ATF_PERM)
988                         state = NUD_PERMANENT;
989                 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ?
990                                    r->arp_ha.sa_data : NULL, state,
991                                    NEIGH_UPDATE_F_OVERRIDE |
992                                    NEIGH_UPDATE_F_ADMIN);
993                 neigh_release(neigh);
994         }
995         return err;
996 }
997 
998 static unsigned int arp_state_to_flags(struct neighbour *neigh)
999 {
1000         if (neigh->nud_state&NUD_PERMANENT)
1001                 return ATF_PERM | ATF_COM;
1002         else if (neigh->nud_state&NUD_VALID)
1003                 return ATF_COM;
1004         else
1005                 return 0;
1006 }
1007 
1008 /*
1009  *      Get an ARP cache entry.
1010  */
1011 
1012 static int arp_req_get(struct arpreq *r, struct net_device *dev)
1013 {
1014         __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1015         struct neighbour *neigh;
1016         int err = -ENXIO;
1017 
1018         neigh = neigh_lookup(&arp_tbl, &ip, dev);
1019         if (neigh) {
1020                 read_lock_bh(&neigh->lock);
1021                 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
1022                 r->arp_flags = arp_state_to_flags(neigh);
1023                 read_unlock_bh(&neigh->lock);
1024                 r->arp_ha.sa_family = dev->type;
1025                 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1026                 neigh_release(neigh);
1027                 err = 0;
1028         }
1029         return err;
1030 }
1031 
1032 static int arp_invalidate(struct net_device *dev, __be32 ip)
1033 {
1034         struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
1035         int err = -ENXIO;
1036 
1037         if (neigh) {
1038                 if (neigh->nud_state & ~NUD_NOARP)
1039                         err = neigh_update(neigh, NULL, NUD_FAILED,
1040                                            NEIGH_UPDATE_F_OVERRIDE|
1041                                            NEIGH_UPDATE_F_ADMIN);
1042                 neigh_release(neigh);
1043         }
1044 
1045         return err;
1046 }
1047 
1048 static int arp_req_delete_public(struct net *net, struct arpreq *r,
1049                 struct net_device *dev)
1050 {
1051         __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1052         __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1053 
1054         if (mask == htonl(0xFFFFFFFF))
1055                 return pneigh_delete(&arp_tbl, net, &ip, dev);
1056 
1057         if (mask)
1058                 return -EINVAL;
1059 
1060         return arp_req_set_proxy(net, dev, 0);
1061 }
1062 
1063 static int arp_req_delete(struct net *net, struct arpreq *r,
1064                           struct net_device *dev)
1065 {
1066         __be32 ip;
1067 
1068         if (r->arp_flags & ATF_PUBL)
1069                 return arp_req_delete_public(net, r, dev);
1070 
1071         ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1072         if (!dev) {
1073                 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1074                 if (IS_ERR(rt))
1075                         return PTR_ERR(rt);
1076                 dev = rt->dst.dev;
1077                 ip_rt_put(rt);
1078                 if (!dev)
1079                         return -EINVAL;
1080         }
1081         return arp_invalidate(dev, ip);
1082 }
1083 
1084 /*
1085  *      Handle an ARP layer I/O control request.
1086  */
1087 
1088 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1089 {
1090         int err;
1091         struct arpreq r;
1092         struct net_device *dev = NULL;
1093 
1094         switch (cmd) {
1095         case SIOCDARP:
1096         case SIOCSARP:
1097                 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1098                         return -EPERM;
1099         case SIOCGARP:
1100                 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1101                 if (err)
1102                         return -EFAULT;
1103                 break;
1104         default:
1105                 return -EINVAL;
1106         }
1107 
1108         if (r.arp_pa.sa_family != AF_INET)
1109                 return -EPFNOSUPPORT;
1110 
1111         if (!(r.arp_flags & ATF_PUBL) &&
1112             (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1113                 return -EINVAL;
1114         if (!(r.arp_flags & ATF_NETMASK))
1115                 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1116                                                            htonl(0xFFFFFFFFUL);
1117         rtnl_lock();
1118         if (r.arp_dev[0]) {
1119                 err = -ENODEV;
1120                 dev = __dev_get_by_name(net, r.arp_dev);
1121                 if (!dev)
1122                         goto out;
1123 
1124                 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1125                 if (!r.arp_ha.sa_family)
1126                         r.arp_ha.sa_family = dev->type;
1127                 err = -EINVAL;
1128                 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1129                         goto out;
1130         } else if (cmd == SIOCGARP) {
1131                 err = -ENODEV;
1132                 goto out;
1133         }
1134 
1135         switch (cmd) {
1136         case SIOCDARP:
1137                 err = arp_req_delete(net, &r, dev);
1138                 break;
1139         case SIOCSARP:
1140                 err = arp_req_set(net, &r, dev);
1141                 break;
1142         case SIOCGARP:
1143                 err = arp_req_get(&r, dev);
1144                 break;
1145         }
1146 out:
1147         rtnl_unlock();
1148         if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
1149                 err = -EFAULT;
1150         return err;
1151 }
1152 
1153 static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1154                             void *ptr)
1155 {
1156         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
1157         struct netdev_notifier_change_info *change_info;
1158 
1159         switch (event) {
1160         case NETDEV_CHANGEADDR:
1161                 neigh_changeaddr(&arp_tbl, dev);
1162                 rt_cache_flush(dev_net(dev));
1163                 break;
1164         case NETDEV_CHANGE:
1165                 change_info = ptr;
1166                 if (change_info->flags_changed & IFF_NOARP)
1167                         neigh_changeaddr(&arp_tbl, dev);
1168                 break;
1169         default:
1170                 break;
1171         }
1172 
1173         return NOTIFY_DONE;
1174 }
1175 
1176 static struct notifier_block arp_netdev_notifier = {
1177         .notifier_call = arp_netdev_event,
1178 };
1179 
1180 /* Note, that it is not on notifier chain.
1181    It is necessary, that this routine was called after route cache will be
1182    flushed.
1183  */
1184 void arp_ifdown(struct net_device *dev)
1185 {
1186         neigh_ifdown(&arp_tbl, dev);
1187 }
1188 
1189 
1190 /*
1191  *      Called once on startup.
1192  */
1193 
1194 static struct packet_type arp_packet_type __read_mostly = {
1195         .type = cpu_to_be16(ETH_P_ARP),
1196         .func = arp_rcv,
1197 };
1198 
1199 static int arp_proc_init(void);
1200 
1201 void __init arp_init(void)
1202 {
1203         neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl);
1204 
1205         dev_add_pack(&arp_packet_type);
1206         arp_proc_init();
1207 #ifdef CONFIG_SYSCTL
1208         neigh_sysctl_register(NULL, &arp_tbl.parms, NULL);
1209 #endif
1210         register_netdevice_notifier(&arp_netdev_notifier);
1211 }
1212 
1213 #ifdef CONFIG_PROC_FS
1214 #if IS_ENABLED(CONFIG_AX25)
1215 
1216 /* ------------------------------------------------------------------------ */
1217 /*
1218  *      ax25 -> ASCII conversion
1219  */
1220 static char *ax2asc2(ax25_address *a, char *buf)
1221 {
1222         char c, *s;
1223         int n;
1224 
1225         for (n = 0, s = buf; n < 6; n++) {
1226                 c = (a->ax25_call[n] >> 1) & 0x7F;
1227 
1228                 if (c != ' ')
1229                         *s++ = c;
1230         }
1231 
1232         *s++ = '-';
1233         n = (a->ax25_call[6] >> 1) & 0x0F;
1234         if (n > 9) {
1235                 *s++ = '1';
1236                 n -= 10;
1237         }
1238 
1239         *s++ = n + '';
1240         *s++ = '\0';
1241 
1242         if (*buf == '\0' || *buf == '-')
1243                 return "*";
1244 
1245         return buf;
1246 }
1247 #endif /* CONFIG_AX25 */
1248 
1249 #define HBUFFERLEN 30
1250 
1251 static void arp_format_neigh_entry(struct seq_file *seq,
1252                                    struct neighbour *n)
1253 {
1254         char hbuffer[HBUFFERLEN];
1255         int k, j;
1256         char tbuf[16];
1257         struct net_device *dev = n->dev;
1258         int hatype = dev->type;
1259 
1260         read_lock(&n->lock);
1261         /* Convert hardware address to XX:XX:XX:XX ... form. */
1262 #if IS_ENABLED(CONFIG_AX25)
1263         if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1264                 ax2asc2((ax25_address *)n->ha, hbuffer);
1265         else {
1266 #endif
1267         for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1268                 hbuffer[k++] = hex_asc_hi(n->ha[j]);
1269                 hbuffer[k++] = hex_asc_lo(n->ha[j]);
1270                 hbuffer[k++] = ':';
1271         }
1272         if (k != 0)
1273                 --k;
1274         hbuffer[k] = 0;
1275 #if IS_ENABLED(CONFIG_AX25)
1276         }
1277 #endif
1278         sprintf(tbuf, "%pI4", n->primary_key);
1279         seq_printf(seq, "%-16s 0x%-10x0x%-10x%s     *        %s\n",
1280                    tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1281         read_unlock(&n->lock);
1282 }
1283 
1284 static void arp_format_pneigh_entry(struct seq_file *seq,
1285                                     struct pneigh_entry *n)
1286 {
1287         struct net_device *dev = n->dev;
1288         int hatype = dev ? dev->type : 0;
1289         char tbuf[16];
1290 
1291         sprintf(tbuf, "%pI4", n->key);
1292         seq_printf(seq, "%-16s 0x%-10x0x%-10x%s     *        %s\n",
1293                    tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1294                    dev ? dev->name : "*");
1295 }
1296 
1297 static int arp_seq_show(struct seq_file *seq, void *v)
1298 {
1299         if (v == SEQ_START_TOKEN) {
1300                 seq_puts(seq, "IP address       HW type     Flags       "
1301                               "HW address            Mask     Device\n");
1302         } else {
1303                 struct neigh_seq_state *state = seq->private;
1304 
1305                 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1306                         arp_format_pneigh_entry(seq, v);
1307                 else
1308                         arp_format_neigh_entry(seq, v);
1309         }
1310 
1311         return 0;
1312 }
1313 
1314 static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1315 {
1316         /* Don't want to confuse "arp -a" w/ magic entries,
1317          * so we tell the generic iterator to skip NUD_NOARP.
1318          */
1319         return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1320 }
1321 
1322 /* ------------------------------------------------------------------------ */
1323 
1324 static const struct seq_operations arp_seq_ops = {
1325         .start  = arp_seq_start,
1326         .next   = neigh_seq_next,
1327         .stop   = neigh_seq_stop,
1328         .show   = arp_seq_show,
1329 };
1330 
1331 static int arp_seq_open(struct inode *inode, struct file *file)
1332 {
1333         return seq_open_net(inode, file, &arp_seq_ops,
1334                             sizeof(struct neigh_seq_state));
1335 }
1336 
1337 static const struct file_operations arp_seq_fops = {
1338         .owner          = THIS_MODULE,
1339         .open           = arp_seq_open,
1340         .read           = seq_read,
1341         .llseek         = seq_lseek,
1342         .release        = seq_release_net,
1343 };
1344 
1345 
1346 static int __net_init arp_net_init(struct net *net)
1347 {
1348         if (!proc_create("arp", S_IRUGO, net->proc_net, &arp_seq_fops))
1349                 return -ENOMEM;
1350         return 0;
1351 }
1352 
1353 static void __net_exit arp_net_exit(struct net *net)
1354 {
1355         remove_proc_entry("arp", net->proc_net);
1356 }
1357 
1358 static struct pernet_operations arp_net_ops = {
1359         .init = arp_net_init,
1360         .exit = arp_net_exit,
1361 };
1362 
1363 static int __init arp_proc_init(void)
1364 {
1365         return register_pernet_subsys(&arp_net_ops);
1366 }
1367 
1368 #else /* CONFIG_PROC_FS */
1369 
1370 static int __init arp_proc_init(void)
1371 {
1372         return 0;
1373 }
1374 
1375 #endif /* CONFIG_PROC_FS */
1376 

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