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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 #include <net/dst_metadata.h>
117 #include <net/ip_tunnels.h>
118 
119 #include <linux/uaccess.h>
120 
121 #include <linux/netfilter_arp.h>
122 
123 /*
124  *      Interface to generic neighbour cache.
125  */
126 static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd);
127 static bool arp_key_eq(const struct neighbour *n, const void *pkey);
128 static int arp_constructor(struct neighbour *neigh);
129 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
130 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
131 static void parp_redo(struct sk_buff *skb);
132 
133 static const struct neigh_ops arp_generic_ops = {
134         .family =               AF_INET,
135         .solicit =              arp_solicit,
136         .error_report =         arp_error_report,
137         .output =               neigh_resolve_output,
138         .connected_output =     neigh_connected_output,
139 };
140 
141 static const struct neigh_ops arp_hh_ops = {
142         .family =               AF_INET,
143         .solicit =              arp_solicit,
144         .error_report =         arp_error_report,
145         .output =               neigh_resolve_output,
146         .connected_output =     neigh_resolve_output,
147 };
148 
149 static const struct neigh_ops arp_direct_ops = {
150         .family =               AF_INET,
151         .output =               neigh_direct_output,
152         .connected_output =     neigh_direct_output,
153 };
154 
155 struct neigh_table arp_tbl = {
156         .family         = AF_INET,
157         .key_len        = 4,
158         .protocol       = cpu_to_be16(ETH_P_IP),
159         .hash           = arp_hash,
160         .key_eq         = arp_key_eq,
161         .constructor    = arp_constructor,
162         .proxy_redo     = parp_redo,
163         .id             = "arp_cache",
164         .parms          = {
165                 .tbl                    = &arp_tbl,
166                 .reachable_time         = 30 * HZ,
167                 .data   = {
168                         [NEIGH_VAR_MCAST_PROBES] = 3,
169                         [NEIGH_VAR_UCAST_PROBES] = 3,
170                         [NEIGH_VAR_RETRANS_TIME] = 1 * HZ,
171                         [NEIGH_VAR_BASE_REACHABLE_TIME] = 30 * HZ,
172                         [NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ,
173                         [NEIGH_VAR_GC_STALETIME] = 60 * HZ,
174                         [NEIGH_VAR_QUEUE_LEN_BYTES] = 64 * 1024,
175                         [NEIGH_VAR_PROXY_QLEN] = 64,
176                         [NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ,
177                         [NEIGH_VAR_PROXY_DELAY] = (8 * HZ) / 10,
178                         [NEIGH_VAR_LOCKTIME] = 1 * HZ,
179                 },
180         },
181         .gc_interval    = 30 * HZ,
182         .gc_thresh1     = 128,
183         .gc_thresh2     = 512,
184         .gc_thresh3     = 1024,
185 };
186 EXPORT_SYMBOL(arp_tbl);
187 
188 int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir)
189 {
190         switch (dev->type) {
191         case ARPHRD_ETHER:
192         case ARPHRD_FDDI:
193         case ARPHRD_IEEE802:
194                 ip_eth_mc_map(addr, haddr);
195                 return 0;
196         case ARPHRD_INFINIBAND:
197                 ip_ib_mc_map(addr, dev->broadcast, haddr);
198                 return 0;
199         case ARPHRD_IPGRE:
200                 ip_ipgre_mc_map(addr, dev->broadcast, haddr);
201                 return 0;
202         default:
203                 if (dir) {
204                         memcpy(haddr, dev->broadcast, dev->addr_len);
205                         return 0;
206                 }
207         }
208         return -EINVAL;
209 }
210 
211 
212 static u32 arp_hash(const void *pkey,
213                     const struct net_device *dev,
214                     __u32 *hash_rnd)
215 {
216         return arp_hashfn(pkey, dev, hash_rnd);
217 }
218 
219 static bool arp_key_eq(const struct neighbour *neigh, const void *pkey)
220 {
221         return neigh_key_eq32(neigh, pkey);
222 }
223 
224 static int arp_constructor(struct neighbour *neigh)
225 {
226         __be32 addr = *(__be32 *)neigh->primary_key;
227         struct net_device *dev = neigh->dev;
228         struct in_device *in_dev;
229         struct neigh_parms *parms;
230 
231         rcu_read_lock();
232         in_dev = __in_dev_get_rcu(dev);
233         if (!in_dev) {
234                 rcu_read_unlock();
235                 return -EINVAL;
236         }
237 
238         neigh->type = inet_addr_type_dev_table(dev_net(dev), dev, addr);
239 
240         parms = in_dev->arp_parms;
241         __neigh_parms_put(neigh->parms);
242         neigh->parms = neigh_parms_clone(parms);
243         rcu_read_unlock();
244 
245         if (!dev->header_ops) {
246                 neigh->nud_state = NUD_NOARP;
247                 neigh->ops = &arp_direct_ops;
248                 neigh->output = neigh_direct_output;
249         } else {
250                 /* Good devices (checked by reading texts, but only Ethernet is
251                    tested)
252 
253                    ARPHRD_ETHER: (ethernet, apfddi)
254                    ARPHRD_FDDI: (fddi)
255                    ARPHRD_IEEE802: (tr)
256                    ARPHRD_METRICOM: (strip)
257                    ARPHRD_ARCNET:
258                    etc. etc. etc.
259 
260                    ARPHRD_IPDDP will also work, if author repairs it.
261                    I did not it, because this driver does not work even
262                    in old paradigm.
263                  */
264 
265                 if (neigh->type == RTN_MULTICAST) {
266                         neigh->nud_state = NUD_NOARP;
267                         arp_mc_map(addr, neigh->ha, dev, 1);
268                 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) {
269                         neigh->nud_state = NUD_NOARP;
270                         memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
271                 } else if (neigh->type == RTN_BROADCAST ||
272                            (dev->flags & IFF_POINTOPOINT)) {
273                         neigh->nud_state = NUD_NOARP;
274                         memcpy(neigh->ha, dev->broadcast, dev->addr_len);
275                 }
276 
277                 if (dev->header_ops->cache)
278                         neigh->ops = &arp_hh_ops;
279                 else
280                         neigh->ops = &arp_generic_ops;
281 
282                 if (neigh->nud_state & NUD_VALID)
283                         neigh->output = neigh->ops->connected_output;
284                 else
285                         neigh->output = neigh->ops->output;
286         }
287         return 0;
288 }
289 
290 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
291 {
292         dst_link_failure(skb);
293         kfree_skb(skb);
294 }
295 
296 /* Create and send an arp packet. */
297 static void arp_send_dst(int type, int ptype, __be32 dest_ip,
298                          struct net_device *dev, __be32 src_ip,
299                          const unsigned char *dest_hw,
300                          const unsigned char *src_hw,
301                          const unsigned char *target_hw,
302                          struct dst_entry *dst)
303 {
304         struct sk_buff *skb;
305 
306         /* arp on this interface. */
307         if (dev->flags & IFF_NOARP)
308                 return;
309 
310         skb = arp_create(type, ptype, dest_ip, dev, src_ip,
311                          dest_hw, src_hw, target_hw);
312         if (!skb)
313                 return;
314 
315         skb_dst_set(skb, dst_clone(dst));
316         arp_xmit(skb);
317 }
318 
319 void arp_send(int type, int ptype, __be32 dest_ip,
320               struct net_device *dev, __be32 src_ip,
321               const unsigned char *dest_hw, const unsigned char *src_hw,
322               const unsigned char *target_hw)
323 {
324         arp_send_dst(type, ptype, dest_ip, dev, src_ip, dest_hw, src_hw,
325                      target_hw, NULL);
326 }
327 EXPORT_SYMBOL(arp_send);
328 
329 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
330 {
331         __be32 saddr = 0;
332         u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL;
333         struct net_device *dev = neigh->dev;
334         __be32 target = *(__be32 *)neigh->primary_key;
335         int probes = atomic_read(&neigh->probes);
336         struct in_device *in_dev;
337         struct dst_entry *dst = NULL;
338 
339         rcu_read_lock();
340         in_dev = __in_dev_get_rcu(dev);
341         if (!in_dev) {
342                 rcu_read_unlock();
343                 return;
344         }
345         switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
346         default:
347         case 0:         /* By default announce any local IP */
348                 if (skb && inet_addr_type_dev_table(dev_net(dev), dev,
349                                           ip_hdr(skb)->saddr) == RTN_LOCAL)
350                         saddr = ip_hdr(skb)->saddr;
351                 break;
352         case 1:         /* Restrict announcements of saddr in same subnet */
353                 if (!skb)
354                         break;
355                 saddr = ip_hdr(skb)->saddr;
356                 if (inet_addr_type_dev_table(dev_net(dev), dev,
357                                              saddr) == RTN_LOCAL) {
358                         /* saddr should be known to target */
359                         if (inet_addr_onlink(in_dev, target, saddr))
360                                 break;
361                 }
362                 saddr = 0;
363                 break;
364         case 2:         /* Avoid secondary IPs, get a primary/preferred one */
365                 break;
366         }
367         rcu_read_unlock();
368 
369         if (!saddr)
370                 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
371 
372         probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES);
373         if (probes < 0) {
374                 if (!(neigh->nud_state & NUD_VALID))
375                         pr_debug("trying to ucast probe in NUD_INVALID\n");
376                 neigh_ha_snapshot(dst_ha, neigh, dev);
377                 dst_hw = dst_ha;
378         } else {
379                 probes -= NEIGH_VAR(neigh->parms, APP_PROBES);
380                 if (probes < 0) {
381                         neigh_app_ns(neigh);
382                         return;
383                 }
384         }
385 
386         if (skb && !(dev->priv_flags & IFF_XMIT_DST_RELEASE))
387                 dst = skb_dst(skb);
388         arp_send_dst(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
389                      dst_hw, dev->dev_addr, NULL, dst);
390 }
391 
392 static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip)
393 {
394         struct net *net = dev_net(in_dev->dev);
395         int scope;
396 
397         switch (IN_DEV_ARP_IGNORE(in_dev)) {
398         case 0: /* Reply, the tip is already validated */
399                 return 0;
400         case 1: /* Reply only if tip is configured on the incoming interface */
401                 sip = 0;
402                 scope = RT_SCOPE_HOST;
403                 break;
404         case 2: /*
405                  * Reply only if tip is configured on the incoming interface
406                  * and is in same subnet as sip
407                  */
408                 scope = RT_SCOPE_HOST;
409                 break;
410         case 3: /* Do not reply for scope host addresses */
411                 sip = 0;
412                 scope = RT_SCOPE_LINK;
413                 in_dev = NULL;
414                 break;
415         case 4: /* Reserved */
416         case 5:
417         case 6:
418         case 7:
419                 return 0;
420         case 8: /* Do not reply */
421                 return 1;
422         default:
423                 return 0;
424         }
425         return !inet_confirm_addr(net, in_dev, sip, tip, scope);
426 }
427 
428 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
429 {
430         struct rtable *rt;
431         int flag = 0;
432         /*unsigned long now; */
433         struct net *net = dev_net(dev);
434 
435         rt = ip_route_output(net, sip, tip, 0, 0);
436         if (IS_ERR(rt))
437                 return 1;
438         if (rt->dst.dev != dev) {
439                 NET_INC_STATS_BH(net, LINUX_MIB_ARPFILTER);
440                 flag = 1;
441         }
442         ip_rt_put(rt);
443         return flag;
444 }
445 
446 /*
447  * Check if we can use proxy ARP for this path
448  */
449 static inline int arp_fwd_proxy(struct in_device *in_dev,
450                                 struct net_device *dev, struct rtable *rt)
451 {
452         struct in_device *out_dev;
453         int imi, omi = -1;
454 
455         if (rt->dst.dev == dev)
456                 return 0;
457 
458         if (!IN_DEV_PROXY_ARP(in_dev))
459                 return 0;
460         imi = IN_DEV_MEDIUM_ID(in_dev);
461         if (imi == 0)
462                 return 1;
463         if (imi == -1)
464                 return 0;
465 
466         /* place to check for proxy_arp for routes */
467 
468         out_dev = __in_dev_get_rcu(rt->dst.dev);
469         if (out_dev)
470                 omi = IN_DEV_MEDIUM_ID(out_dev);
471 
472         return omi != imi && omi != -1;
473 }
474 
475 /*
476  * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
477  *
478  * RFC3069 supports proxy arp replies back to the same interface.  This
479  * is done to support (ethernet) switch features, like RFC 3069, where
480  * the individual ports are not allowed to communicate with each
481  * other, BUT they are allowed to talk to the upstream router.  As
482  * described in RFC 3069, it is possible to allow these hosts to
483  * communicate through the upstream router, by proxy_arp'ing.
484  *
485  * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
486  *
487  *  This technology is known by different names:
488  *    In RFC 3069 it is called VLAN Aggregation.
489  *    Cisco and Allied Telesyn call it Private VLAN.
490  *    Hewlett-Packard call it Source-Port filtering or port-isolation.
491  *    Ericsson call it MAC-Forced Forwarding (RFC Draft).
492  *
493  */
494 static inline int arp_fwd_pvlan(struct in_device *in_dev,
495                                 struct net_device *dev, struct rtable *rt,
496                                 __be32 sip, __be32 tip)
497 {
498         /* Private VLAN is only concerned about the same ethernet segment */
499         if (rt->dst.dev != dev)
500                 return 0;
501 
502         /* Don't reply on self probes (often done by windowz boxes)*/
503         if (sip == tip)
504                 return 0;
505 
506         if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
507                 return 1;
508         else
509                 return 0;
510 }
511 
512 /*
513  *      Interface to link layer: send routine and receive handler.
514  */
515 
516 /*
517  *      Create an arp packet. If dest_hw is not set, we create a broadcast
518  *      message.
519  */
520 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
521                            struct net_device *dev, __be32 src_ip,
522                            const unsigned char *dest_hw,
523                            const unsigned char *src_hw,
524                            const unsigned char *target_hw)
525 {
526         struct sk_buff *skb;
527         struct arphdr *arp;
528         unsigned char *arp_ptr;
529         int hlen = LL_RESERVED_SPACE(dev);
530         int tlen = dev->needed_tailroom;
531 
532         /*
533          *      Allocate a buffer
534          */
535 
536         skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
537         if (!skb)
538                 return NULL;
539 
540         skb_reserve(skb, hlen);
541         skb_reset_network_header(skb);
542         arp = (struct arphdr *) skb_put(skb, arp_hdr_len(dev));
543         skb->dev = dev;
544         skb->protocol = htons(ETH_P_ARP);
545         if (!src_hw)
546                 src_hw = dev->dev_addr;
547         if (!dest_hw)
548                 dest_hw = dev->broadcast;
549 
550         /*
551          *      Fill the device header for the ARP frame
552          */
553         if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
554                 goto out;
555 
556         /*
557          * Fill out the arp protocol part.
558          *
559          * The arp hardware type should match the device type, except for FDDI,
560          * which (according to RFC 1390) should always equal 1 (Ethernet).
561          */
562         /*
563          *      Exceptions everywhere. AX.25 uses the AX.25 PID value not the
564          *      DIX code for the protocol. Make these device structure fields.
565          */
566         switch (dev->type) {
567         default:
568                 arp->ar_hrd = htons(dev->type);
569                 arp->ar_pro = htons(ETH_P_IP);
570                 break;
571 
572 #if IS_ENABLED(CONFIG_AX25)
573         case ARPHRD_AX25:
574                 arp->ar_hrd = htons(ARPHRD_AX25);
575                 arp->ar_pro = htons(AX25_P_IP);
576                 break;
577 
578 #if IS_ENABLED(CONFIG_NETROM)
579         case ARPHRD_NETROM:
580                 arp->ar_hrd = htons(ARPHRD_NETROM);
581                 arp->ar_pro = htons(AX25_P_IP);
582                 break;
583 #endif
584 #endif
585 
586 #if IS_ENABLED(CONFIG_FDDI)
587         case ARPHRD_FDDI:
588                 arp->ar_hrd = htons(ARPHRD_ETHER);
589                 arp->ar_pro = htons(ETH_P_IP);
590                 break;
591 #endif
592         }
593 
594         arp->ar_hln = dev->addr_len;
595         arp->ar_pln = 4;
596         arp->ar_op = htons(type);
597 
598         arp_ptr = (unsigned char *)(arp + 1);
599 
600         memcpy(arp_ptr, src_hw, dev->addr_len);
601         arp_ptr += dev->addr_len;
602         memcpy(arp_ptr, &src_ip, 4);
603         arp_ptr += 4;
604 
605         switch (dev->type) {
606 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
607         case ARPHRD_IEEE1394:
608                 break;
609 #endif
610         default:
611                 if (target_hw)
612                         memcpy(arp_ptr, target_hw, dev->addr_len);
613                 else
614                         memset(arp_ptr, 0, dev->addr_len);
615                 arp_ptr += dev->addr_len;
616         }
617         memcpy(arp_ptr, &dest_ip, 4);
618 
619         return skb;
620 
621 out:
622         kfree_skb(skb);
623         return NULL;
624 }
625 EXPORT_SYMBOL(arp_create);
626 
627 static int arp_xmit_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
628 {
629         return dev_queue_xmit(skb);
630 }
631 
632 /*
633  *      Send an arp packet.
634  */
635 void arp_xmit(struct sk_buff *skb)
636 {
637         /* Send it off, maybe filter it using firewalling first.  */
638         NF_HOOK(NFPROTO_ARP, NF_ARP_OUT,
639                 dev_net(skb->dev), NULL, skb, NULL, skb->dev,
640                 arp_xmit_finish);
641 }
642 EXPORT_SYMBOL(arp_xmit);
643 
644 /*
645  *      Process an arp request.
646  */
647 
648 static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb)
649 {
650         struct net_device *dev = skb->dev;
651         struct in_device *in_dev = __in_dev_get_rcu(dev);
652         struct arphdr *arp;
653         unsigned char *arp_ptr;
654         struct rtable *rt;
655         unsigned char *sha;
656         __be32 sip, tip;
657         u16 dev_type = dev->type;
658         int addr_type;
659         struct neighbour *n;
660         struct dst_entry *reply_dst = NULL;
661         bool is_garp = false;
662 
663         /* arp_rcv below verifies the ARP header and verifies the device
664          * is ARP'able.
665          */
666 
667         if (!in_dev)
668                 goto out_free_skb;
669 
670         arp = arp_hdr(skb);
671 
672         switch (dev_type) {
673         default:
674                 if (arp->ar_pro != htons(ETH_P_IP) ||
675                     htons(dev_type) != arp->ar_hrd)
676                         goto out_free_skb;
677                 break;
678         case ARPHRD_ETHER:
679         case ARPHRD_FDDI:
680         case ARPHRD_IEEE802:
681                 /*
682                  * ETHERNET, and Fibre Channel (which are IEEE 802
683                  * devices, according to RFC 2625) devices will accept ARP
684                  * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
685                  * This is the case also of FDDI, where the RFC 1390 says that
686                  * FDDI devices should accept ARP hardware of (1) Ethernet,
687                  * however, to be more robust, we'll accept both 1 (Ethernet)
688                  * or 6 (IEEE 802.2)
689                  */
690                 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
691                      arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
692                     arp->ar_pro != htons(ETH_P_IP))
693                         goto out_free_skb;
694                 break;
695         case ARPHRD_AX25:
696                 if (arp->ar_pro != htons(AX25_P_IP) ||
697                     arp->ar_hrd != htons(ARPHRD_AX25))
698                         goto out_free_skb;
699                 break;
700         case ARPHRD_NETROM:
701                 if (arp->ar_pro != htons(AX25_P_IP) ||
702                     arp->ar_hrd != htons(ARPHRD_NETROM))
703                         goto out_free_skb;
704                 break;
705         }
706 
707         /* Understand only these message types */
708 
709         if (arp->ar_op != htons(ARPOP_REPLY) &&
710             arp->ar_op != htons(ARPOP_REQUEST))
711                 goto out_free_skb;
712 
713 /*
714  *      Extract fields
715  */
716         arp_ptr = (unsigned char *)(arp + 1);
717         sha     = arp_ptr;
718         arp_ptr += dev->addr_len;
719         memcpy(&sip, arp_ptr, 4);
720         arp_ptr += 4;
721         switch (dev_type) {
722 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
723         case ARPHRD_IEEE1394:
724                 break;
725 #endif
726         default:
727                 arp_ptr += dev->addr_len;
728         }
729         memcpy(&tip, arp_ptr, 4);
730 /*
731  *      Check for bad requests for 127.x.x.x and requests for multicast
732  *      addresses.  If this is one such, delete it.
733  */
734         if (ipv4_is_multicast(tip) ||
735             (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip)))
736                 goto out_free_skb;
737 
738  /*
739   *     For some 802.11 wireless deployments (and possibly other networks),
740   *     there will be an ARP proxy and gratuitous ARP frames are attacks
741   *     and thus should not be accepted.
742   */
743         if (sip == tip && IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP))
744                 goto out_free_skb;
745 
746 /*
747  *     Special case: We must set Frame Relay source Q.922 address
748  */
749         if (dev_type == ARPHRD_DLCI)
750                 sha = dev->broadcast;
751 
752 /*
753  *  Process entry.  The idea here is we want to send a reply if it is a
754  *  request for us or if it is a request for someone else that we hold
755  *  a proxy for.  We want to add an entry to our cache if it is a reply
756  *  to us or if it is a request for our address.
757  *  (The assumption for this last is that if someone is requesting our
758  *  address, they are probably intending to talk to us, so it saves time
759  *  if we cache their address.  Their address is also probably not in
760  *  our cache, since ours is not in their cache.)
761  *
762  *  Putting this another way, we only care about replies if they are to
763  *  us, in which case we add them to the cache.  For requests, we care
764  *  about those for us and those for our proxies.  We reply to both,
765  *  and in the case of requests for us we add the requester to the arp
766  *  cache.
767  */
768 
769         if (arp->ar_op == htons(ARPOP_REQUEST) && skb_metadata_dst(skb))
770                 reply_dst = (struct dst_entry *)
771                             iptunnel_metadata_reply(skb_metadata_dst(skb),
772                                                     GFP_ATOMIC);
773 
774         /* Special case: IPv4 duplicate address detection packet (RFC2131) */
775         if (sip == 0) {
776                 if (arp->ar_op == htons(ARPOP_REQUEST) &&
777                     inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL &&
778                     !arp_ignore(in_dev, sip, tip))
779                         arp_send_dst(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip,
780                                      sha, dev->dev_addr, sha, reply_dst);
781                 goto out_consume_skb;
782         }
783 
784         if (arp->ar_op == htons(ARPOP_REQUEST) &&
785             ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
786 
787                 rt = skb_rtable(skb);
788                 addr_type = rt->rt_type;
789 
790                 if (addr_type == RTN_LOCAL) {
791                         int dont_send;
792 
793                         dont_send = arp_ignore(in_dev, sip, tip);
794                         if (!dont_send && IN_DEV_ARPFILTER(in_dev))
795                                 dont_send = arp_filter(sip, tip, dev);
796                         if (!dont_send) {
797                                 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
798                                 if (n) {
799                                         arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
800                                                      sip, dev, tip, sha,
801                                                      dev->dev_addr, sha,
802                                                      reply_dst);
803                                         neigh_release(n);
804                                 }
805                         }
806                         goto out_consume_skb;
807                 } else if (IN_DEV_FORWARD(in_dev)) {
808                         if (addr_type == RTN_UNICAST  &&
809                             (arp_fwd_proxy(in_dev, dev, rt) ||
810                              arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
811                              (rt->dst.dev != dev &&
812                               pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
813                                 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
814                                 if (n)
815                                         neigh_release(n);
816 
817                                 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
818                                     skb->pkt_type == PACKET_HOST ||
819                                     NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) {
820                                         arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
821                                                      sip, dev, tip, sha,
822                                                      dev->dev_addr, sha,
823                                                      reply_dst);
824                                 } else {
825                                         pneigh_enqueue(&arp_tbl,
826                                                        in_dev->arp_parms, skb);
827                                         goto out_free_dst;
828                                 }
829                                 goto out_consume_skb;
830                         }
831                 }
832         }
833 
834         /* Update our ARP tables */
835 
836         n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
837 
838         if (IN_DEV_ARP_ACCEPT(in_dev)) {
839                 unsigned int addr_type = inet_addr_type_dev_table(net, dev, sip);
840 
841                 /* Unsolicited ARP is not accepted by default.
842                    It is possible, that this option should be enabled for some
843                    devices (strip is candidate)
844                  */
845                 is_garp = arp->ar_op == htons(ARPOP_REQUEST) && tip == sip &&
846                           addr_type == RTN_UNICAST;
847 
848                 if (!n &&
849                     ((arp->ar_op == htons(ARPOP_REPLY)  &&
850                                 addr_type == RTN_UNICAST) || is_garp))
851                         n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
852         }
853 
854         if (n) {
855                 int state = NUD_REACHABLE;
856                 int override;
857 
858                 /* If several different ARP replies follows back-to-back,
859                    use the FIRST one. It is possible, if several proxy
860                    agents are active. Taking the first reply prevents
861                    arp trashing and chooses the fastest router.
862                  */
863                 override = time_after(jiffies,
864                                       n->updated +
865                                       NEIGH_VAR(n->parms, LOCKTIME)) ||
866                            is_garp;
867 
868                 /* Broadcast replies and request packets
869                    do not assert neighbour reachability.
870                  */
871                 if (arp->ar_op != htons(ARPOP_REPLY) ||
872                     skb->pkt_type != PACKET_HOST)
873                         state = NUD_STALE;
874                 neigh_update(n, sha, state,
875                              override ? NEIGH_UPDATE_F_OVERRIDE : 0);
876                 neigh_release(n);
877         }
878 
879 out_consume_skb:
880         consume_skb(skb);
881 
882 out_free_dst:
883         dst_release(reply_dst);
884         return NET_RX_SUCCESS;
885 
886 out_free_skb:
887         kfree_skb(skb);
888         return NET_RX_DROP;
889 }
890 
891 static void parp_redo(struct sk_buff *skb)
892 {
893         arp_process(dev_net(skb->dev), NULL, skb);
894 }
895 
896 
897 /*
898  *      Receive an arp request from the device layer.
899  */
900 
901 static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
902                    struct packet_type *pt, struct net_device *orig_dev)
903 {
904         const struct arphdr *arp;
905 
906         /* do not tweak dropwatch on an ARP we will ignore */
907         if (dev->flags & IFF_NOARP ||
908             skb->pkt_type == PACKET_OTHERHOST ||
909             skb->pkt_type == PACKET_LOOPBACK)
910                 goto consumeskb;
911 
912         skb = skb_share_check(skb, GFP_ATOMIC);
913         if (!skb)
914                 goto out_of_mem;
915 
916         /* ARP header, plus 2 device addresses, plus 2 IP addresses.  */
917         if (!pskb_may_pull(skb, arp_hdr_len(dev)))
918                 goto freeskb;
919 
920         arp = arp_hdr(skb);
921         if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4)
922                 goto freeskb;
923 
924         memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
925 
926         return NF_HOOK(NFPROTO_ARP, NF_ARP_IN,
927                        dev_net(dev), NULL, skb, dev, NULL,
928                        arp_process);
929 
930 consumeskb:
931         consume_skb(skb);
932         return NET_RX_SUCCESS;
933 freeskb:
934         kfree_skb(skb);
935 out_of_mem:
936         return NET_RX_DROP;
937 }
938 
939 /*
940  *      User level interface (ioctl)
941  */
942 
943 /*
944  *      Set (create) an ARP cache entry.
945  */
946 
947 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
948 {
949         if (!dev) {
950                 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
951                 return 0;
952         }
953         if (__in_dev_get_rtnl(dev)) {
954                 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
955                 return 0;
956         }
957         return -ENXIO;
958 }
959 
960 static int arp_req_set_public(struct net *net, struct arpreq *r,
961                 struct net_device *dev)
962 {
963         __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
964         __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
965 
966         if (mask && mask != htonl(0xFFFFFFFF))
967                 return -EINVAL;
968         if (!dev && (r->arp_flags & ATF_COM)) {
969                 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family,
970                                       r->arp_ha.sa_data);
971                 if (!dev)
972                         return -ENODEV;
973         }
974         if (mask) {
975                 if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1))
976                         return -ENOBUFS;
977                 return 0;
978         }
979 
980         return arp_req_set_proxy(net, dev, 1);
981 }
982 
983 static int arp_req_set(struct net *net, struct arpreq *r,
984                        struct net_device *dev)
985 {
986         __be32 ip;
987         struct neighbour *neigh;
988         int err;
989 
990         if (r->arp_flags & ATF_PUBL)
991                 return arp_req_set_public(net, r, dev);
992 
993         ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
994         if (r->arp_flags & ATF_PERM)
995                 r->arp_flags |= ATF_COM;
996         if (!dev) {
997                 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
998 
999                 if (IS_ERR(rt))
1000                         return PTR_ERR(rt);
1001                 dev = rt->dst.dev;
1002                 ip_rt_put(rt);
1003                 if (!dev)
1004                         return -EINVAL;
1005         }
1006         switch (dev->type) {
1007 #if IS_ENABLED(CONFIG_FDDI)
1008         case ARPHRD_FDDI:
1009                 /*
1010                  * According to RFC 1390, FDDI devices should accept ARP
1011                  * hardware types of 1 (Ethernet).  However, to be more
1012                  * robust, we'll accept hardware types of either 1 (Ethernet)
1013                  * or 6 (IEEE 802.2).
1014                  */
1015                 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1016                     r->arp_ha.sa_family != ARPHRD_ETHER &&
1017                     r->arp_ha.sa_family != ARPHRD_IEEE802)
1018                         return -EINVAL;
1019                 break;
1020 #endif
1021         default:
1022                 if (r->arp_ha.sa_family != dev->type)
1023                         return -EINVAL;
1024                 break;
1025         }
1026 
1027         neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1028         err = PTR_ERR(neigh);
1029         if (!IS_ERR(neigh)) {
1030                 unsigned int state = NUD_STALE;
1031                 if (r->arp_flags & ATF_PERM)
1032                         state = NUD_PERMANENT;
1033                 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ?
1034                                    r->arp_ha.sa_data : NULL, state,
1035                                    NEIGH_UPDATE_F_OVERRIDE |
1036                                    NEIGH_UPDATE_F_ADMIN);
1037                 neigh_release(neigh);
1038         }
1039         return err;
1040 }
1041 
1042 static unsigned int arp_state_to_flags(struct neighbour *neigh)
1043 {
1044         if (neigh->nud_state&NUD_PERMANENT)
1045                 return ATF_PERM | ATF_COM;
1046         else if (neigh->nud_state&NUD_VALID)
1047                 return ATF_COM;
1048         else
1049                 return 0;
1050 }
1051 
1052 /*
1053  *      Get an ARP cache entry.
1054  */
1055 
1056 static int arp_req_get(struct arpreq *r, struct net_device *dev)
1057 {
1058         __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1059         struct neighbour *neigh;
1060         int err = -ENXIO;
1061 
1062         neigh = neigh_lookup(&arp_tbl, &ip, dev);
1063         if (neigh) {
1064                 if (!(neigh->nud_state & NUD_NOARP)) {
1065                         read_lock_bh(&neigh->lock);
1066                         memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
1067                         r->arp_flags = arp_state_to_flags(neigh);
1068                         read_unlock_bh(&neigh->lock);
1069                         r->arp_ha.sa_family = dev->type;
1070                         strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1071                         err = 0;
1072                 }
1073                 neigh_release(neigh);
1074         }
1075         return err;
1076 }
1077 
1078 static int arp_invalidate(struct net_device *dev, __be32 ip)
1079 {
1080         struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
1081         int err = -ENXIO;
1082 
1083         if (neigh) {
1084                 if (neigh->nud_state & ~NUD_NOARP)
1085                         err = neigh_update(neigh, NULL, NUD_FAILED,
1086                                            NEIGH_UPDATE_F_OVERRIDE|
1087                                            NEIGH_UPDATE_F_ADMIN);
1088                 neigh_release(neigh);
1089         }
1090 
1091         return err;
1092 }
1093 
1094 static int arp_req_delete_public(struct net *net, struct arpreq *r,
1095                 struct net_device *dev)
1096 {
1097         __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1098         __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1099 
1100         if (mask == htonl(0xFFFFFFFF))
1101                 return pneigh_delete(&arp_tbl, net, &ip, dev);
1102 
1103         if (mask)
1104                 return -EINVAL;
1105 
1106         return arp_req_set_proxy(net, dev, 0);
1107 }
1108 
1109 static int arp_req_delete(struct net *net, struct arpreq *r,
1110                           struct net_device *dev)
1111 {
1112         __be32 ip;
1113 
1114         if (r->arp_flags & ATF_PUBL)
1115                 return arp_req_delete_public(net, r, dev);
1116 
1117         ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1118         if (!dev) {
1119                 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1120                 if (IS_ERR(rt))
1121                         return PTR_ERR(rt);
1122                 dev = rt->dst.dev;
1123                 ip_rt_put(rt);
1124                 if (!dev)
1125                         return -EINVAL;
1126         }
1127         return arp_invalidate(dev, ip);
1128 }
1129 
1130 /*
1131  *      Handle an ARP layer I/O control request.
1132  */
1133 
1134 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1135 {
1136         int err;
1137         struct arpreq r;
1138         struct net_device *dev = NULL;
1139 
1140         switch (cmd) {
1141         case SIOCDARP:
1142         case SIOCSARP:
1143                 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1144                         return -EPERM;
1145         case SIOCGARP:
1146                 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1147                 if (err)
1148                         return -EFAULT;
1149                 break;
1150         default:
1151                 return -EINVAL;
1152         }
1153 
1154         if (r.arp_pa.sa_family != AF_INET)
1155                 return -EPFNOSUPPORT;
1156 
1157         if (!(r.arp_flags & ATF_PUBL) &&
1158             (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1159                 return -EINVAL;
1160         if (!(r.arp_flags & ATF_NETMASK))
1161                 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1162                                                            htonl(0xFFFFFFFFUL);
1163         rtnl_lock();
1164         if (r.arp_dev[0]) {
1165                 err = -ENODEV;
1166                 dev = __dev_get_by_name(net, r.arp_dev);
1167                 if (!dev)
1168                         goto out;
1169 
1170                 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1171                 if (!r.arp_ha.sa_family)
1172                         r.arp_ha.sa_family = dev->type;
1173                 err = -EINVAL;
1174                 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1175                         goto out;
1176         } else if (cmd == SIOCGARP) {
1177                 err = -ENODEV;
1178                 goto out;
1179         }
1180 
1181         switch (cmd) {
1182         case SIOCDARP:
1183                 err = arp_req_delete(net, &r, dev);
1184                 break;
1185         case SIOCSARP:
1186                 err = arp_req_set(net, &r, dev);
1187                 break;
1188         case SIOCGARP:
1189                 err = arp_req_get(&r, dev);
1190                 break;
1191         }
1192 out:
1193         rtnl_unlock();
1194         if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
1195                 err = -EFAULT;
1196         return err;
1197 }
1198 
1199 static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1200                             void *ptr)
1201 {
1202         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
1203         struct netdev_notifier_change_info *change_info;
1204 
1205         switch (event) {
1206         case NETDEV_CHANGEADDR:
1207                 neigh_changeaddr(&arp_tbl, dev);
1208                 rt_cache_flush(dev_net(dev));
1209                 break;
1210         case NETDEV_CHANGE:
1211                 change_info = ptr;
1212                 if (change_info->flags_changed & IFF_NOARP)
1213                         neigh_changeaddr(&arp_tbl, dev);
1214                 break;
1215         default:
1216                 break;
1217         }
1218 
1219         return NOTIFY_DONE;
1220 }
1221 
1222 static struct notifier_block arp_netdev_notifier = {
1223         .notifier_call = arp_netdev_event,
1224 };
1225 
1226 /* Note, that it is not on notifier chain.
1227    It is necessary, that this routine was called after route cache will be
1228    flushed.
1229  */
1230 void arp_ifdown(struct net_device *dev)
1231 {
1232         neigh_ifdown(&arp_tbl, dev);
1233 }
1234 
1235 
1236 /*
1237  *      Called once on startup.
1238  */
1239 
1240 static struct packet_type arp_packet_type __read_mostly = {
1241         .type = cpu_to_be16(ETH_P_ARP),
1242         .func = arp_rcv,
1243 };
1244 
1245 static int arp_proc_init(void);
1246 
1247 void __init arp_init(void)
1248 {
1249         neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl);
1250 
1251         dev_add_pack(&arp_packet_type);
1252         arp_proc_init();
1253 #ifdef CONFIG_SYSCTL
1254         neigh_sysctl_register(NULL, &arp_tbl.parms, NULL);
1255 #endif
1256         register_netdevice_notifier(&arp_netdev_notifier);
1257 }
1258 
1259 #ifdef CONFIG_PROC_FS
1260 #if IS_ENABLED(CONFIG_AX25)
1261 
1262 /* ------------------------------------------------------------------------ */
1263 /*
1264  *      ax25 -> ASCII conversion
1265  */
1266 static char *ax2asc2(ax25_address *a, char *buf)
1267 {
1268         char c, *s;
1269         int n;
1270 
1271         for (n = 0, s = buf; n < 6; n++) {
1272                 c = (a->ax25_call[n] >> 1) & 0x7F;
1273 
1274                 if (c != ' ')
1275                         *s++ = c;
1276         }
1277 
1278         *s++ = '-';
1279         n = (a->ax25_call[6] >> 1) & 0x0F;
1280         if (n > 9) {
1281                 *s++ = '1';
1282                 n -= 10;
1283         }
1284 
1285         *s++ = n + '';
1286         *s++ = '\0';
1287 
1288         if (*buf == '\0' || *buf == '-')
1289                 return "*";
1290 
1291         return buf;
1292 }
1293 #endif /* CONFIG_AX25 */
1294 
1295 #define HBUFFERLEN 30
1296 
1297 static void arp_format_neigh_entry(struct seq_file *seq,
1298                                    struct neighbour *n)
1299 {
1300         char hbuffer[HBUFFERLEN];
1301         int k, j;
1302         char tbuf[16];
1303         struct net_device *dev = n->dev;
1304         int hatype = dev->type;
1305 
1306         read_lock(&n->lock);
1307         /* Convert hardware address to XX:XX:XX:XX ... form. */
1308 #if IS_ENABLED(CONFIG_AX25)
1309         if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1310                 ax2asc2((ax25_address *)n->ha, hbuffer);
1311         else {
1312 #endif
1313         for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1314                 hbuffer[k++] = hex_asc_hi(n->ha[j]);
1315                 hbuffer[k++] = hex_asc_lo(n->ha[j]);
1316                 hbuffer[k++] = ':';
1317         }
1318         if (k != 0)
1319                 --k;
1320         hbuffer[k] = 0;
1321 #if IS_ENABLED(CONFIG_AX25)
1322         }
1323 #endif
1324         sprintf(tbuf, "%pI4", n->primary_key);
1325         seq_printf(seq, "%-16s 0x%-10x0x%-10x%s     *        %s\n",
1326                    tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1327         read_unlock(&n->lock);
1328 }
1329 
1330 static void arp_format_pneigh_entry(struct seq_file *seq,
1331                                     struct pneigh_entry *n)
1332 {
1333         struct net_device *dev = n->dev;
1334         int hatype = dev ? dev->type : 0;
1335         char tbuf[16];
1336 
1337         sprintf(tbuf, "%pI4", n->key);
1338         seq_printf(seq, "%-16s 0x%-10x0x%-10x%s     *        %s\n",
1339                    tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1340                    dev ? dev->name : "*");
1341 }
1342 
1343 static int arp_seq_show(struct seq_file *seq, void *v)
1344 {
1345         if (v == SEQ_START_TOKEN) {
1346                 seq_puts(seq, "IP address       HW type     Flags       "
1347                               "HW address            Mask     Device\n");
1348         } else {
1349                 struct neigh_seq_state *state = seq->private;
1350 
1351                 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1352                         arp_format_pneigh_entry(seq, v);
1353                 else
1354                         arp_format_neigh_entry(seq, v);
1355         }
1356 
1357         return 0;
1358 }
1359 
1360 static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1361 {
1362         /* Don't want to confuse "arp -a" w/ magic entries,
1363          * so we tell the generic iterator to skip NUD_NOARP.
1364          */
1365         return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1366 }
1367 
1368 /* ------------------------------------------------------------------------ */
1369 
1370 static const struct seq_operations arp_seq_ops = {
1371         .start  = arp_seq_start,
1372         .next   = neigh_seq_next,
1373         .stop   = neigh_seq_stop,
1374         .show   = arp_seq_show,
1375 };
1376 
1377 static int arp_seq_open(struct inode *inode, struct file *file)
1378 {
1379         return seq_open_net(inode, file, &arp_seq_ops,
1380                             sizeof(struct neigh_seq_state));
1381 }
1382 
1383 static const struct file_operations arp_seq_fops = {
1384         .owner          = THIS_MODULE,
1385         .open           = arp_seq_open,
1386         .read           = seq_read,
1387         .llseek         = seq_lseek,
1388         .release        = seq_release_net,
1389 };
1390 
1391 
1392 static int __net_init arp_net_init(struct net *net)
1393 {
1394         if (!proc_create("arp", S_IRUGO, net->proc_net, &arp_seq_fops))
1395                 return -ENOMEM;
1396         return 0;
1397 }
1398 
1399 static void __net_exit arp_net_exit(struct net *net)
1400 {
1401         remove_proc_entry("arp", net->proc_net);
1402 }
1403 
1404 static struct pernet_operations arp_net_ops = {
1405         .init = arp_net_init,
1406         .exit = arp_net_exit,
1407 };
1408 
1409 static int __init arp_proc_init(void)
1410 {
1411         return register_pernet_subsys(&arp_net_ops);
1412 }
1413 
1414 #else /* CONFIG_PROC_FS */
1415 
1416 static int __init arp_proc_init(void)
1417 {
1418         return 0;
1419 }
1420 
1421 #endif /* CONFIG_PROC_FS */
1422 

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