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Linux/net/ipv4/arp.c

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  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 int arp_constructor(struct neighbour *neigh);
126 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
127 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
128 static void parp_redo(struct sk_buff *skb);
129 
130 static const struct neigh_ops arp_generic_ops = {
131         .family =               AF_INET,
132         .solicit =              arp_solicit,
133         .error_report =         arp_error_report,
134         .output =               neigh_resolve_output,
135         .connected_output =     neigh_connected_output,
136 };
137 
138 static const struct neigh_ops arp_hh_ops = {
139         .family =               AF_INET,
140         .solicit =              arp_solicit,
141         .error_report =         arp_error_report,
142         .output =               neigh_resolve_output,
143         .connected_output =     neigh_resolve_output,
144 };
145 
146 static const struct neigh_ops arp_direct_ops = {
147         .family =               AF_INET,
148         .output =               neigh_direct_output,
149         .connected_output =     neigh_direct_output,
150 };
151 
152 static const struct neigh_ops arp_broken_ops = {
153         .family =               AF_INET,
154         .solicit =              arp_solicit,
155         .error_report =         arp_error_report,
156         .output =               neigh_compat_output,
157         .connected_output =     neigh_compat_output,
158 };
159 
160 struct neigh_table arp_tbl = {
161         .family         = AF_INET,
162         .key_len        = 4,
163         .hash           = arp_hash,
164         .constructor    = arp_constructor,
165         .proxy_redo     = parp_redo,
166         .id             = "arp_cache",
167         .parms          = {
168                 .tbl                    = &arp_tbl,
169                 .base_reachable_time    = 30 * HZ,
170                 .retrans_time           = 1 * HZ,
171                 .gc_staletime           = 60 * HZ,
172                 .reachable_time         = 30 * HZ,
173                 .delay_probe_time       = 5 * HZ,
174                 .queue_len_bytes        = 64*1024,
175                 .ucast_probes           = 3,
176                 .mcast_probes           = 3,
177                 .anycast_delay          = 1 * HZ,
178                 .proxy_delay            = (8 * HZ) / 10,
179                 .proxy_qlen             = 64,
180                 .locktime               = 1 * HZ,
181         },
182         .gc_interval    = 30 * HZ,
183         .gc_thresh1     = 128,
184         .gc_thresh2     = 512,
185         .gc_thresh3     = 1024,
186 };
187 EXPORT_SYMBOL(arp_tbl);
188 
189 int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir)
190 {
191         switch (dev->type) {
192         case ARPHRD_ETHER:
193         case ARPHRD_FDDI:
194         case ARPHRD_IEEE802:
195                 ip_eth_mc_map(addr, haddr);
196                 return 0;
197         case ARPHRD_INFINIBAND:
198                 ip_ib_mc_map(addr, dev->broadcast, haddr);
199                 return 0;
200         case ARPHRD_IPGRE:
201                 ip_ipgre_mc_map(addr, dev->broadcast, haddr);
202                 return 0;
203         default:
204                 if (dir) {
205                         memcpy(haddr, dev->broadcast, dev->addr_len);
206                         return 0;
207                 }
208         }
209         return -EINVAL;
210 }
211 
212 
213 static u32 arp_hash(const void *pkey,
214                     const struct net_device *dev,
215                     __u32 *hash_rnd)
216 {
217         return arp_hashfn(*(u32 *)pkey, dev, *hash_rnd);
218 }
219 
220 static int arp_constructor(struct neighbour *neigh)
221 {
222         __be32 addr = *(__be32 *)neigh->primary_key;
223         struct net_device *dev = neigh->dev;
224         struct in_device *in_dev;
225         struct neigh_parms *parms;
226 
227         rcu_read_lock();
228         in_dev = __in_dev_get_rcu(dev);
229         if (in_dev == NULL) {
230                 rcu_read_unlock();
231                 return -EINVAL;
232         }
233 
234         neigh->type = inet_addr_type(dev_net(dev), addr);
235 
236         parms = in_dev->arp_parms;
237         __neigh_parms_put(neigh->parms);
238         neigh->parms = neigh_parms_clone(parms);
239         rcu_read_unlock();
240 
241         if (!dev->header_ops) {
242                 neigh->nud_state = NUD_NOARP;
243                 neigh->ops = &arp_direct_ops;
244                 neigh->output = neigh_direct_output;
245         } else {
246                 /* Good devices (checked by reading texts, but only Ethernet is
247                    tested)
248 
249                    ARPHRD_ETHER: (ethernet, apfddi)
250                    ARPHRD_FDDI: (fddi)
251                    ARPHRD_IEEE802: (tr)
252                    ARPHRD_METRICOM: (strip)
253                    ARPHRD_ARCNET:
254                    etc. etc. etc.
255 
256                    ARPHRD_IPDDP will also work, if author repairs it.
257                    I did not it, because this driver does not work even
258                    in old paradigm.
259                  */
260 
261 #if 1
262                 /* So... these "amateur" devices are hopeless.
263                    The only thing, that I can say now:
264                    It is very sad that we need to keep ugly obsolete
265                    code to make them happy.
266 
267                    They should be moved to more reasonable state, now
268                    they use rebuild_header INSTEAD OF hard_start_xmit!!!
269                    Besides that, they are sort of out of date
270                    (a lot of redundant clones/copies, useless in 2.1),
271                    I wonder why people believe that they work.
272                  */
273                 switch (dev->type) {
274                 default:
275                         break;
276                 case ARPHRD_ROSE:
277 #if IS_ENABLED(CONFIG_AX25)
278                 case ARPHRD_AX25:
279 #if IS_ENABLED(CONFIG_NETROM)
280                 case ARPHRD_NETROM:
281 #endif
282                         neigh->ops = &arp_broken_ops;
283                         neigh->output = neigh->ops->output;
284                         return 0;
285 #else
286                         break;
287 #endif
288                 }
289 #endif
290                 if (neigh->type == RTN_MULTICAST) {
291                         neigh->nud_state = NUD_NOARP;
292                         arp_mc_map(addr, neigh->ha, dev, 1);
293                 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) {
294                         neigh->nud_state = NUD_NOARP;
295                         memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
296                 } else if (neigh->type == RTN_BROADCAST ||
297                            (dev->flags & IFF_POINTOPOINT)) {
298                         neigh->nud_state = NUD_NOARP;
299                         memcpy(neigh->ha, dev->broadcast, dev->addr_len);
300                 }
301 
302                 if (dev->header_ops->cache)
303                         neigh->ops = &arp_hh_ops;
304                 else
305                         neigh->ops = &arp_generic_ops;
306 
307                 if (neigh->nud_state & NUD_VALID)
308                         neigh->output = neigh->ops->connected_output;
309                 else
310                         neigh->output = neigh->ops->output;
311         }
312         return 0;
313 }
314 
315 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
316 {
317         dst_link_failure(skb);
318         kfree_skb(skb);
319 }
320 
321 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
322 {
323         __be32 saddr = 0;
324         u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL;
325         struct net_device *dev = neigh->dev;
326         __be32 target = *(__be32 *)neigh->primary_key;
327         int probes = atomic_read(&neigh->probes);
328         struct in_device *in_dev;
329 
330         rcu_read_lock();
331         in_dev = __in_dev_get_rcu(dev);
332         if (!in_dev) {
333                 rcu_read_unlock();
334                 return;
335         }
336         switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
337         default:
338         case 0:         /* By default announce any local IP */
339                 if (skb && inet_addr_type(dev_net(dev),
340                                           ip_hdr(skb)->saddr) == RTN_LOCAL)
341                         saddr = ip_hdr(skb)->saddr;
342                 break;
343         case 1:         /* Restrict announcements of saddr in same subnet */
344                 if (!skb)
345                         break;
346                 saddr = ip_hdr(skb)->saddr;
347                 if (inet_addr_type(dev_net(dev), saddr) == RTN_LOCAL) {
348                         /* saddr should be known to target */
349                         if (inet_addr_onlink(in_dev, target, saddr))
350                                 break;
351                 }
352                 saddr = 0;
353                 break;
354         case 2:         /* Avoid secondary IPs, get a primary/preferred one */
355                 break;
356         }
357         rcu_read_unlock();
358 
359         if (!saddr)
360                 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
361 
362         probes -= neigh->parms->ucast_probes;
363         if (probes < 0) {
364                 if (!(neigh->nud_state & NUD_VALID))
365                         pr_debug("trying to ucast probe in NUD_INVALID\n");
366                 neigh_ha_snapshot(dst_ha, neigh, dev);
367                 dst_hw = dst_ha;
368         } else {
369                 probes -= neigh->parms->app_probes;
370                 if (probes < 0) {
371 #ifdef CONFIG_ARPD
372                         neigh_app_ns(neigh);
373 #endif
374                         return;
375                 }
376         }
377 
378         arp_send(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
379                  dst_hw, dev->dev_addr, NULL);
380 }
381 
382 static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip)
383 {
384         int scope;
385 
386         switch (IN_DEV_ARP_IGNORE(in_dev)) {
387         case 0: /* Reply, the tip is already validated */
388                 return 0;
389         case 1: /* Reply only if tip is configured on the incoming interface */
390                 sip = 0;
391                 scope = RT_SCOPE_HOST;
392                 break;
393         case 2: /*
394                  * Reply only if tip is configured on the incoming interface
395                  * and is in same subnet as sip
396                  */
397                 scope = RT_SCOPE_HOST;
398                 break;
399         case 3: /* Do not reply for scope host addresses */
400                 sip = 0;
401                 scope = RT_SCOPE_LINK;
402                 break;
403         case 4: /* Reserved */
404         case 5:
405         case 6:
406         case 7:
407                 return 0;
408         case 8: /* Do not reply */
409                 return 1;
410         default:
411                 return 0;
412         }
413         return !inet_confirm_addr(in_dev, sip, tip, scope);
414 }
415 
416 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
417 {
418         struct rtable *rt;
419         int flag = 0;
420         /*unsigned long now; */
421         struct net *net = dev_net(dev);
422 
423         rt = ip_route_output(net, sip, tip, 0, 0);
424         if (IS_ERR(rt))
425                 return 1;
426         if (rt->dst.dev != dev) {
427                 NET_INC_STATS_BH(net, LINUX_MIB_ARPFILTER);
428                 flag = 1;
429         }
430         ip_rt_put(rt);
431         return flag;
432 }
433 
434 /* OBSOLETE FUNCTIONS */
435 
436 /*
437  *      Find an arp mapping in the cache. If not found, post a request.
438  *
439  *      It is very UGLY routine: it DOES NOT use skb->dst->neighbour,
440  *      even if it exists. It is supposed that skb->dev was mangled
441  *      by a virtual device (eql, shaper). Nobody but broken devices
442  *      is allowed to use this function, it is scheduled to be removed. --ANK
443  */
444 
445 static int arp_set_predefined(int addr_hint, unsigned char *haddr,
446                               __be32 paddr, struct net_device *dev)
447 {
448         switch (addr_hint) {
449         case RTN_LOCAL:
450                 pr_debug("arp called for own IP address\n");
451                 memcpy(haddr, dev->dev_addr, dev->addr_len);
452                 return 1;
453         case RTN_MULTICAST:
454                 arp_mc_map(paddr, haddr, dev, 1);
455                 return 1;
456         case RTN_BROADCAST:
457                 memcpy(haddr, dev->broadcast, dev->addr_len);
458                 return 1;
459         }
460         return 0;
461 }
462 
463 
464 int arp_find(unsigned char *haddr, struct sk_buff *skb)
465 {
466         struct net_device *dev = skb->dev;
467         __be32 paddr;
468         struct neighbour *n;
469 
470         if (!skb_dst(skb)) {
471                 pr_debug("arp_find is called with dst==NULL\n");
472                 kfree_skb(skb);
473                 return 1;
474         }
475 
476         paddr = rt_nexthop(skb_rtable(skb), ip_hdr(skb)->daddr);
477         if (arp_set_predefined(inet_addr_type(dev_net(dev), paddr), haddr,
478                                paddr, dev))
479                 return 0;
480 
481         n = __neigh_lookup(&arp_tbl, &paddr, dev, 1);
482 
483         if (n) {
484                 n->used = jiffies;
485                 if (n->nud_state & NUD_VALID || neigh_event_send(n, skb) == 0) {
486                         neigh_ha_snapshot(haddr, n, dev);
487                         neigh_release(n);
488                         return 0;
489                 }
490                 neigh_release(n);
491         } else
492                 kfree_skb(skb);
493         return 1;
494 }
495 EXPORT_SYMBOL(arp_find);
496 
497 /* END OF OBSOLETE FUNCTIONS */
498 
499 /*
500  * Check if we can use proxy ARP for this path
501  */
502 static inline int arp_fwd_proxy(struct in_device *in_dev,
503                                 struct net_device *dev, struct rtable *rt)
504 {
505         struct in_device *out_dev;
506         int imi, omi = -1;
507 
508         if (rt->dst.dev == dev)
509                 return 0;
510 
511         if (!IN_DEV_PROXY_ARP(in_dev))
512                 return 0;
513         imi = IN_DEV_MEDIUM_ID(in_dev);
514         if (imi == 0)
515                 return 1;
516         if (imi == -1)
517                 return 0;
518 
519         /* place to check for proxy_arp for routes */
520 
521         out_dev = __in_dev_get_rcu(rt->dst.dev);
522         if (out_dev)
523                 omi = IN_DEV_MEDIUM_ID(out_dev);
524 
525         return omi != imi && omi != -1;
526 }
527 
528 /*
529  * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
530  *
531  * RFC3069 supports proxy arp replies back to the same interface.  This
532  * is done to support (ethernet) switch features, like RFC 3069, where
533  * the individual ports are not allowed to communicate with each
534  * other, BUT they are allowed to talk to the upstream router.  As
535  * described in RFC 3069, it is possible to allow these hosts to
536  * communicate through the upstream router, by proxy_arp'ing.
537  *
538  * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
539  *
540  *  This technology is known by different names:
541  *    In RFC 3069 it is called VLAN Aggregation.
542  *    Cisco and Allied Telesyn call it Private VLAN.
543  *    Hewlett-Packard call it Source-Port filtering or port-isolation.
544  *    Ericsson call it MAC-Forced Forwarding (RFC Draft).
545  *
546  */
547 static inline int arp_fwd_pvlan(struct in_device *in_dev,
548                                 struct net_device *dev, struct rtable *rt,
549                                 __be32 sip, __be32 tip)
550 {
551         /* Private VLAN is only concerned about the same ethernet segment */
552         if (rt->dst.dev != dev)
553                 return 0;
554 
555         /* Don't reply on self probes (often done by windowz boxes)*/
556         if (sip == tip)
557                 return 0;
558 
559         if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
560                 return 1;
561         else
562                 return 0;
563 }
564 
565 /*
566  *      Interface to link layer: send routine and receive handler.
567  */
568 
569 /*
570  *      Create an arp packet. If (dest_hw == NULL), we create a broadcast
571  *      message.
572  */
573 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
574                            struct net_device *dev, __be32 src_ip,
575                            const unsigned char *dest_hw,
576                            const unsigned char *src_hw,
577                            const unsigned char *target_hw)
578 {
579         struct sk_buff *skb;
580         struct arphdr *arp;
581         unsigned char *arp_ptr;
582         int hlen = LL_RESERVED_SPACE(dev);
583         int tlen = dev->needed_tailroom;
584 
585         /*
586          *      Allocate a buffer
587          */
588 
589         skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
590         if (skb == NULL)
591                 return NULL;
592 
593         skb_reserve(skb, hlen);
594         skb_reset_network_header(skb);
595         arp = (struct arphdr *) skb_put(skb, arp_hdr_len(dev));
596         skb->dev = dev;
597         skb->protocol = htons(ETH_P_ARP);
598         if (src_hw == NULL)
599                 src_hw = dev->dev_addr;
600         if (dest_hw == NULL)
601                 dest_hw = dev->broadcast;
602 
603         /*
604          *      Fill the device header for the ARP frame
605          */
606         if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
607                 goto out;
608 
609         /*
610          * Fill out the arp protocol part.
611          *
612          * The arp hardware type should match the device type, except for FDDI,
613          * which (according to RFC 1390) should always equal 1 (Ethernet).
614          */
615         /*
616          *      Exceptions everywhere. AX.25 uses the AX.25 PID value not the
617          *      DIX code for the protocol. Make these device structure fields.
618          */
619         switch (dev->type) {
620         default:
621                 arp->ar_hrd = htons(dev->type);
622                 arp->ar_pro = htons(ETH_P_IP);
623                 break;
624 
625 #if IS_ENABLED(CONFIG_AX25)
626         case ARPHRD_AX25:
627                 arp->ar_hrd = htons(ARPHRD_AX25);
628                 arp->ar_pro = htons(AX25_P_IP);
629                 break;
630 
631 #if IS_ENABLED(CONFIG_NETROM)
632         case ARPHRD_NETROM:
633                 arp->ar_hrd = htons(ARPHRD_NETROM);
634                 arp->ar_pro = htons(AX25_P_IP);
635                 break;
636 #endif
637 #endif
638 
639 #if IS_ENABLED(CONFIG_FDDI)
640         case ARPHRD_FDDI:
641                 arp->ar_hrd = htons(ARPHRD_ETHER);
642                 arp->ar_pro = htons(ETH_P_IP);
643                 break;
644 #endif
645         }
646 
647         arp->ar_hln = dev->addr_len;
648         arp->ar_pln = 4;
649         arp->ar_op = htons(type);
650 
651         arp_ptr = (unsigned char *)(arp + 1);
652 
653         memcpy(arp_ptr, src_hw, dev->addr_len);
654         arp_ptr += dev->addr_len;
655         memcpy(arp_ptr, &src_ip, 4);
656         arp_ptr += 4;
657 
658         switch (dev->type) {
659 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
660         case ARPHRD_IEEE1394:
661                 break;
662 #endif
663         default:
664                 if (target_hw != NULL)
665                         memcpy(arp_ptr, target_hw, dev->addr_len);
666                 else
667                         memset(arp_ptr, 0, dev->addr_len);
668                 arp_ptr += dev->addr_len;
669         }
670         memcpy(arp_ptr, &dest_ip, 4);
671 
672         return skb;
673 
674 out:
675         kfree_skb(skb);
676         return NULL;
677 }
678 EXPORT_SYMBOL(arp_create);
679 
680 /*
681  *      Send an arp packet.
682  */
683 void arp_xmit(struct sk_buff *skb)
684 {
685         /* Send it off, maybe filter it using firewalling first.  */
686         NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, skb, NULL, skb->dev, dev_queue_xmit);
687 }
688 EXPORT_SYMBOL(arp_xmit);
689 
690 /*
691  *      Create and send an arp packet.
692  */
693 void arp_send(int type, int ptype, __be32 dest_ip,
694               struct net_device *dev, __be32 src_ip,
695               const unsigned char *dest_hw, const unsigned char *src_hw,
696               const unsigned char *target_hw)
697 {
698         struct sk_buff *skb;
699 
700         /*
701          *      No arp on this interface.
702          */
703 
704         if (dev->flags&IFF_NOARP)
705                 return;
706 
707         skb = arp_create(type, ptype, dest_ip, dev, src_ip,
708                          dest_hw, src_hw, target_hw);
709         if (skb == NULL)
710                 return;
711 
712         arp_xmit(skb);
713 }
714 EXPORT_SYMBOL(arp_send);
715 
716 /*
717  *      Process an arp request.
718  */
719 
720 static int arp_process(struct sk_buff *skb)
721 {
722         struct net_device *dev = skb->dev;
723         struct in_device *in_dev = __in_dev_get_rcu(dev);
724         struct arphdr *arp;
725         unsigned char *arp_ptr;
726         struct rtable *rt;
727         unsigned char *sha;
728         __be32 sip, tip;
729         u16 dev_type = dev->type;
730         int addr_type;
731         struct neighbour *n;
732         struct net *net = dev_net(dev);
733 
734         /* arp_rcv below verifies the ARP header and verifies the device
735          * is ARP'able.
736          */
737 
738         if (in_dev == NULL)
739                 goto out;
740 
741         arp = arp_hdr(skb);
742 
743         switch (dev_type) {
744         default:
745                 if (arp->ar_pro != htons(ETH_P_IP) ||
746                     htons(dev_type) != arp->ar_hrd)
747                         goto out;
748                 break;
749         case ARPHRD_ETHER:
750         case ARPHRD_FDDI:
751         case ARPHRD_IEEE802:
752                 /*
753                  * ETHERNET, and Fibre Channel (which are IEEE 802
754                  * devices, according to RFC 2625) devices will accept ARP
755                  * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
756                  * This is the case also of FDDI, where the RFC 1390 says that
757                  * FDDI devices should accept ARP hardware of (1) Ethernet,
758                  * however, to be more robust, we'll accept both 1 (Ethernet)
759                  * or 6 (IEEE 802.2)
760                  */
761                 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
762                      arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
763                     arp->ar_pro != htons(ETH_P_IP))
764                         goto out;
765                 break;
766         case ARPHRD_AX25:
767                 if (arp->ar_pro != htons(AX25_P_IP) ||
768                     arp->ar_hrd != htons(ARPHRD_AX25))
769                         goto out;
770                 break;
771         case ARPHRD_NETROM:
772                 if (arp->ar_pro != htons(AX25_P_IP) ||
773                     arp->ar_hrd != htons(ARPHRD_NETROM))
774                         goto out;
775                 break;
776         }
777 
778         /* Understand only these message types */
779 
780         if (arp->ar_op != htons(ARPOP_REPLY) &&
781             arp->ar_op != htons(ARPOP_REQUEST))
782                 goto out;
783 
784 /*
785  *      Extract fields
786  */
787         arp_ptr = (unsigned char *)(arp + 1);
788         sha     = arp_ptr;
789         arp_ptr += dev->addr_len;
790         memcpy(&sip, arp_ptr, 4);
791         arp_ptr += 4;
792         switch (dev_type) {
793 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
794         case ARPHRD_IEEE1394:
795                 break;
796 #endif
797         default:
798                 arp_ptr += dev->addr_len;
799         }
800         memcpy(&tip, arp_ptr, 4);
801 /*
802  *      Check for bad requests for 127.x.x.x and requests for multicast
803  *      addresses.  If this is one such, delete it.
804  */
805         if (ipv4_is_multicast(tip) ||
806             (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip)))
807                 goto out;
808 
809 /*
810  *     Special case: We must set Frame Relay source Q.922 address
811  */
812         if (dev_type == ARPHRD_DLCI)
813                 sha = dev->broadcast;
814 
815 /*
816  *  Process entry.  The idea here is we want to send a reply if it is a
817  *  request for us or if it is a request for someone else that we hold
818  *  a proxy for.  We want to add an entry to our cache if it is a reply
819  *  to us or if it is a request for our address.
820  *  (The assumption for this last is that if someone is requesting our
821  *  address, they are probably intending to talk to us, so it saves time
822  *  if we cache their address.  Their address is also probably not in
823  *  our cache, since ours is not in their cache.)
824  *
825  *  Putting this another way, we only care about replies if they are to
826  *  us, in which case we add them to the cache.  For requests, we care
827  *  about those for us and those for our proxies.  We reply to both,
828  *  and in the case of requests for us we add the requester to the arp
829  *  cache.
830  */
831 
832         /* Special case: IPv4 duplicate address detection packet (RFC2131) */
833         if (sip == 0) {
834                 if (arp->ar_op == htons(ARPOP_REQUEST) &&
835                     inet_addr_type(net, tip) == RTN_LOCAL &&
836                     !arp_ignore(in_dev, sip, tip))
837                         arp_send(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, sha,
838                                  dev->dev_addr, sha);
839                 goto out;
840         }
841 
842         if (arp->ar_op == htons(ARPOP_REQUEST) &&
843             ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
844 
845                 rt = skb_rtable(skb);
846                 addr_type = rt->rt_type;
847 
848                 if (addr_type == RTN_LOCAL) {
849                         int dont_send;
850 
851                         dont_send = arp_ignore(in_dev, sip, tip);
852                         if (!dont_send && IN_DEV_ARPFILTER(in_dev))
853                                 dont_send = arp_filter(sip, tip, dev);
854                         if (!dont_send) {
855                                 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
856                                 if (n) {
857                                         arp_send(ARPOP_REPLY, ETH_P_ARP, sip,
858                                                  dev, tip, sha, dev->dev_addr,
859                                                  sha);
860                                         neigh_release(n);
861                                 }
862                         }
863                         goto out;
864                 } else if (IN_DEV_FORWARD(in_dev)) {
865                         if (addr_type == RTN_UNICAST  &&
866                             (arp_fwd_proxy(in_dev, dev, rt) ||
867                              arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
868                              (rt->dst.dev != dev &&
869                               pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
870                                 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
871                                 if (n)
872                                         neigh_release(n);
873 
874                                 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
875                                     skb->pkt_type == PACKET_HOST ||
876                                     in_dev->arp_parms->proxy_delay == 0) {
877                                         arp_send(ARPOP_REPLY, ETH_P_ARP, sip,
878                                                  dev, tip, sha, dev->dev_addr,
879                                                  sha);
880                                 } else {
881                                         pneigh_enqueue(&arp_tbl,
882                                                        in_dev->arp_parms, skb);
883                                         return 0;
884                                 }
885                                 goto out;
886                         }
887                 }
888         }
889 
890         /* Update our ARP tables */
891 
892         n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
893 
894         if (IN_DEV_ARP_ACCEPT(in_dev)) {
895                 /* Unsolicited ARP is not accepted by default.
896                    It is possible, that this option should be enabled for some
897                    devices (strip is candidate)
898                  */
899                 if (n == NULL &&
900                     (arp->ar_op == htons(ARPOP_REPLY) ||
901                      (arp->ar_op == htons(ARPOP_REQUEST) && tip == sip)) &&
902                     inet_addr_type(net, sip) == RTN_UNICAST)
903                         n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
904         }
905 
906         if (n) {
907                 int state = NUD_REACHABLE;
908                 int override;
909 
910                 /* If several different ARP replies follows back-to-back,
911                    use the FIRST one. It is possible, if several proxy
912                    agents are active. Taking the first reply prevents
913                    arp trashing and chooses the fastest router.
914                  */
915                 override = time_after(jiffies, n->updated + n->parms->locktime);
916 
917                 /* Broadcast replies and request packets
918                    do not assert neighbour reachability.
919                  */
920                 if (arp->ar_op != htons(ARPOP_REPLY) ||
921                     skb->pkt_type != PACKET_HOST)
922                         state = NUD_STALE;
923                 neigh_update(n, sha, state,
924                              override ? NEIGH_UPDATE_F_OVERRIDE : 0);
925                 neigh_release(n);
926         }
927 
928 out:
929         consume_skb(skb);
930         return 0;
931 }
932 
933 static void parp_redo(struct sk_buff *skb)
934 {
935         arp_process(skb);
936 }
937 
938 
939 /*
940  *      Receive an arp request from the device layer.
941  */
942 
943 static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
944                    struct packet_type *pt, struct net_device *orig_dev)
945 {
946         const struct arphdr *arp;
947 
948         if (dev->flags & IFF_NOARP ||
949             skb->pkt_type == PACKET_OTHERHOST ||
950             skb->pkt_type == PACKET_LOOPBACK)
951                 goto freeskb;
952 
953         skb = skb_share_check(skb, GFP_ATOMIC);
954         if (!skb)
955                 goto out_of_mem;
956 
957         /* ARP header, plus 2 device addresses, plus 2 IP addresses.  */
958         if (!pskb_may_pull(skb, arp_hdr_len(dev)))
959                 goto freeskb;
960 
961         arp = arp_hdr(skb);
962         if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4)
963                 goto freeskb;
964 
965         memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
966 
967         return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, skb, dev, NULL, arp_process);
968 
969 freeskb:
970         kfree_skb(skb);
971 out_of_mem:
972         return 0;
973 }
974 
975 /*
976  *      User level interface (ioctl)
977  */
978 
979 /*
980  *      Set (create) an ARP cache entry.
981  */
982 
983 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
984 {
985         if (dev == NULL) {
986                 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
987                 return 0;
988         }
989         if (__in_dev_get_rtnl(dev)) {
990                 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
991                 return 0;
992         }
993         return -ENXIO;
994 }
995 
996 static int arp_req_set_public(struct net *net, struct arpreq *r,
997                 struct net_device *dev)
998 {
999         __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1000         __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1001 
1002         if (mask && mask != htonl(0xFFFFFFFF))
1003                 return -EINVAL;
1004         if (!dev && (r->arp_flags & ATF_COM)) {
1005                 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family,
1006                                       r->arp_ha.sa_data);
1007                 if (!dev)
1008                         return -ENODEV;
1009         }
1010         if (mask) {
1011                 if (pneigh_lookup(&arp_tbl, net, &ip, dev, 1) == NULL)
1012                         return -ENOBUFS;
1013                 return 0;
1014         }
1015 
1016         return arp_req_set_proxy(net, dev, 1);
1017 }
1018 
1019 static int arp_req_set(struct net *net, struct arpreq *r,
1020                        struct net_device *dev)
1021 {
1022         __be32 ip;
1023         struct neighbour *neigh;
1024         int err;
1025 
1026         if (r->arp_flags & ATF_PUBL)
1027                 return arp_req_set_public(net, r, dev);
1028 
1029         ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1030         if (r->arp_flags & ATF_PERM)
1031                 r->arp_flags |= ATF_COM;
1032         if (dev == NULL) {
1033                 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1034 
1035                 if (IS_ERR(rt))
1036                         return PTR_ERR(rt);
1037                 dev = rt->dst.dev;
1038                 ip_rt_put(rt);
1039                 if (!dev)
1040                         return -EINVAL;
1041         }
1042         switch (dev->type) {
1043 #if IS_ENABLED(CONFIG_FDDI)
1044         case ARPHRD_FDDI:
1045                 /*
1046                  * According to RFC 1390, FDDI devices should accept ARP
1047                  * hardware types of 1 (Ethernet).  However, to be more
1048                  * robust, we'll accept hardware types of either 1 (Ethernet)
1049                  * or 6 (IEEE 802.2).
1050                  */
1051                 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1052                     r->arp_ha.sa_family != ARPHRD_ETHER &&
1053                     r->arp_ha.sa_family != ARPHRD_IEEE802)
1054                         return -EINVAL;
1055                 break;
1056 #endif
1057         default:
1058                 if (r->arp_ha.sa_family != dev->type)
1059                         return -EINVAL;
1060                 break;
1061         }
1062 
1063         neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1064         err = PTR_ERR(neigh);
1065         if (!IS_ERR(neigh)) {
1066                 unsigned int state = NUD_STALE;
1067                 if (r->arp_flags & ATF_PERM)
1068                         state = NUD_PERMANENT;
1069                 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ?
1070                                    r->arp_ha.sa_data : NULL, state,
1071                                    NEIGH_UPDATE_F_OVERRIDE |
1072                                    NEIGH_UPDATE_F_ADMIN);
1073                 neigh_release(neigh);
1074         }
1075         return err;
1076 }
1077 
1078 static unsigned int arp_state_to_flags(struct neighbour *neigh)
1079 {
1080         if (neigh->nud_state&NUD_PERMANENT)
1081                 return ATF_PERM | ATF_COM;
1082         else if (neigh->nud_state&NUD_VALID)
1083                 return ATF_COM;
1084         else
1085                 return 0;
1086 }
1087 
1088 /*
1089  *      Get an ARP cache entry.
1090  */
1091 
1092 static int arp_req_get(struct arpreq *r, struct net_device *dev)
1093 {
1094         __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1095         struct neighbour *neigh;
1096         int err = -ENXIO;
1097 
1098         neigh = neigh_lookup(&arp_tbl, &ip, dev);
1099         if (neigh) {
1100                 read_lock_bh(&neigh->lock);
1101                 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
1102                 r->arp_flags = arp_state_to_flags(neigh);
1103                 read_unlock_bh(&neigh->lock);
1104                 r->arp_ha.sa_family = dev->type;
1105                 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1106                 neigh_release(neigh);
1107                 err = 0;
1108         }
1109         return err;
1110 }
1111 
1112 int arp_invalidate(struct net_device *dev, __be32 ip)
1113 {
1114         struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
1115         int err = -ENXIO;
1116 
1117         if (neigh) {
1118                 if (neigh->nud_state & ~NUD_NOARP)
1119                         err = neigh_update(neigh, NULL, NUD_FAILED,
1120                                            NEIGH_UPDATE_F_OVERRIDE|
1121                                            NEIGH_UPDATE_F_ADMIN);
1122                 neigh_release(neigh);
1123         }
1124 
1125         return err;
1126 }
1127 EXPORT_SYMBOL(arp_invalidate);
1128 
1129 static int arp_req_delete_public(struct net *net, struct arpreq *r,
1130                 struct net_device *dev)
1131 {
1132         __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1133         __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1134 
1135         if (mask == htonl(0xFFFFFFFF))
1136                 return pneigh_delete(&arp_tbl, net, &ip, dev);
1137 
1138         if (mask)
1139                 return -EINVAL;
1140 
1141         return arp_req_set_proxy(net, dev, 0);
1142 }
1143 
1144 static int arp_req_delete(struct net *net, struct arpreq *r,
1145                           struct net_device *dev)
1146 {
1147         __be32 ip;
1148 
1149         if (r->arp_flags & ATF_PUBL)
1150                 return arp_req_delete_public(net, r, dev);
1151 
1152         ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1153         if (dev == NULL) {
1154                 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1155                 if (IS_ERR(rt))
1156                         return PTR_ERR(rt);
1157                 dev = rt->dst.dev;
1158                 ip_rt_put(rt);
1159                 if (!dev)
1160                         return -EINVAL;
1161         }
1162         return arp_invalidate(dev, ip);
1163 }
1164 
1165 /*
1166  *      Handle an ARP layer I/O control request.
1167  */
1168 
1169 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1170 {
1171         int err;
1172         struct arpreq r;
1173         struct net_device *dev = NULL;
1174 
1175         switch (cmd) {
1176         case SIOCDARP:
1177         case SIOCSARP:
1178                 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1179                         return -EPERM;
1180         case SIOCGARP:
1181                 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1182                 if (err)
1183                         return -EFAULT;
1184                 break;
1185         default:
1186                 return -EINVAL;
1187         }
1188 
1189         if (r.arp_pa.sa_family != AF_INET)
1190                 return -EPFNOSUPPORT;
1191 
1192         if (!(r.arp_flags & ATF_PUBL) &&
1193             (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1194                 return -EINVAL;
1195         if (!(r.arp_flags & ATF_NETMASK))
1196                 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1197                                                            htonl(0xFFFFFFFFUL);
1198         rtnl_lock();
1199         if (r.arp_dev[0]) {
1200                 err = -ENODEV;
1201                 dev = __dev_get_by_name(net, r.arp_dev);
1202                 if (dev == NULL)
1203                         goto out;
1204 
1205                 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1206                 if (!r.arp_ha.sa_family)
1207                         r.arp_ha.sa_family = dev->type;
1208                 err = -EINVAL;
1209                 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1210                         goto out;
1211         } else if (cmd == SIOCGARP) {
1212                 err = -ENODEV;
1213                 goto out;
1214         }
1215 
1216         switch (cmd) {
1217         case SIOCDARP:
1218                 err = arp_req_delete(net, &r, dev);
1219                 break;
1220         case SIOCSARP:
1221                 err = arp_req_set(net, &r, dev);
1222                 break;
1223         case SIOCGARP:
1224                 err = arp_req_get(&r, dev);
1225                 break;
1226         }
1227 out:
1228         rtnl_unlock();
1229         if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
1230                 err = -EFAULT;
1231         return err;
1232 }
1233 
1234 static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1235                             void *ptr)
1236 {
1237         struct net_device *dev = ptr;
1238 
1239         switch (event) {
1240         case NETDEV_CHANGEADDR:
1241                 neigh_changeaddr(&arp_tbl, dev);
1242                 rt_cache_flush(dev_net(dev));
1243                 break;
1244         default:
1245                 break;
1246         }
1247 
1248         return NOTIFY_DONE;
1249 }
1250 
1251 static struct notifier_block arp_netdev_notifier = {
1252         .notifier_call = arp_netdev_event,
1253 };
1254 
1255 /* Note, that it is not on notifier chain.
1256    It is necessary, that this routine was called after route cache will be
1257    flushed.
1258  */
1259 void arp_ifdown(struct net_device *dev)
1260 {
1261         neigh_ifdown(&arp_tbl, dev);
1262 }
1263 
1264 
1265 /*
1266  *      Called once on startup.
1267  */
1268 
1269 static struct packet_type arp_packet_type __read_mostly = {
1270         .type = cpu_to_be16(ETH_P_ARP),
1271         .func = arp_rcv,
1272 };
1273 
1274 static int arp_proc_init(void);
1275 
1276 void __init arp_init(void)
1277 {
1278         neigh_table_init(&arp_tbl);
1279 
1280         dev_add_pack(&arp_packet_type);
1281         arp_proc_init();
1282 #ifdef CONFIG_SYSCTL
1283         neigh_sysctl_register(NULL, &arp_tbl.parms, "ipv4", NULL);
1284 #endif
1285         register_netdevice_notifier(&arp_netdev_notifier);
1286 }
1287 
1288 #ifdef CONFIG_PROC_FS
1289 #if IS_ENABLED(CONFIG_AX25)
1290 
1291 /* ------------------------------------------------------------------------ */
1292 /*
1293  *      ax25 -> ASCII conversion
1294  */
1295 static char *ax2asc2(ax25_address *a, char *buf)
1296 {
1297         char c, *s;
1298         int n;
1299 
1300         for (n = 0, s = buf; n < 6; n++) {
1301                 c = (a->ax25_call[n] >> 1) & 0x7F;
1302 
1303                 if (c != ' ')
1304                         *s++ = c;
1305         }
1306 
1307         *s++ = '-';
1308         n = (a->ax25_call[6] >> 1) & 0x0F;
1309         if (n > 9) {
1310                 *s++ = '1';
1311                 n -= 10;
1312         }
1313 
1314         *s++ = n + '';
1315         *s++ = '\0';
1316 
1317         if (*buf == '\0' || *buf == '-')
1318                 return "*";
1319 
1320         return buf;
1321 }
1322 #endif /* CONFIG_AX25 */
1323 
1324 #define HBUFFERLEN 30
1325 
1326 static void arp_format_neigh_entry(struct seq_file *seq,
1327                                    struct neighbour *n)
1328 {
1329         char hbuffer[HBUFFERLEN];
1330         int k, j;
1331         char tbuf[16];
1332         struct net_device *dev = n->dev;
1333         int hatype = dev->type;
1334 
1335         read_lock(&n->lock);
1336         /* Convert hardware address to XX:XX:XX:XX ... form. */
1337 #if IS_ENABLED(CONFIG_AX25)
1338         if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1339                 ax2asc2((ax25_address *)n->ha, hbuffer);
1340         else {
1341 #endif
1342         for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1343                 hbuffer[k++] = hex_asc_hi(n->ha[j]);
1344                 hbuffer[k++] = hex_asc_lo(n->ha[j]);
1345                 hbuffer[k++] = ':';
1346         }
1347         if (k != 0)
1348                 --k;
1349         hbuffer[k] = 0;
1350 #if IS_ENABLED(CONFIG_AX25)
1351         }
1352 #endif
1353         sprintf(tbuf, "%pI4", n->primary_key);
1354         seq_printf(seq, "%-16s 0x%-10x0x%-10x%s     *        %s\n",
1355                    tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1356         read_unlock(&n->lock);
1357 }
1358 
1359 static void arp_format_pneigh_entry(struct seq_file *seq,
1360                                     struct pneigh_entry *n)
1361 {
1362         struct net_device *dev = n->dev;
1363         int hatype = dev ? dev->type : 0;
1364         char tbuf[16];
1365 
1366         sprintf(tbuf, "%pI4", n->key);
1367         seq_printf(seq, "%-16s 0x%-10x0x%-10x%s     *        %s\n",
1368                    tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1369                    dev ? dev->name : "*");
1370 }
1371 
1372 static int arp_seq_show(struct seq_file *seq, void *v)
1373 {
1374         if (v == SEQ_START_TOKEN) {
1375                 seq_puts(seq, "IP address       HW type     Flags       "
1376                               "HW address            Mask     Device\n");
1377         } else {
1378                 struct neigh_seq_state *state = seq->private;
1379 
1380                 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1381                         arp_format_pneigh_entry(seq, v);
1382                 else
1383                         arp_format_neigh_entry(seq, v);
1384         }
1385 
1386         return 0;
1387 }
1388 
1389 static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1390 {
1391         /* Don't want to confuse "arp -a" w/ magic entries,
1392          * so we tell the generic iterator to skip NUD_NOARP.
1393          */
1394         return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1395 }
1396 
1397 /* ------------------------------------------------------------------------ */
1398 
1399 static const struct seq_operations arp_seq_ops = {
1400         .start  = arp_seq_start,
1401         .next   = neigh_seq_next,
1402         .stop   = neigh_seq_stop,
1403         .show   = arp_seq_show,
1404 };
1405 
1406 static int arp_seq_open(struct inode *inode, struct file *file)
1407 {
1408         return seq_open_net(inode, file, &arp_seq_ops,
1409                             sizeof(struct neigh_seq_state));
1410 }
1411 
1412 static const struct file_operations arp_seq_fops = {
1413         .owner          = THIS_MODULE,
1414         .open           = arp_seq_open,
1415         .read           = seq_read,
1416         .llseek         = seq_lseek,
1417         .release        = seq_release_net,
1418 };
1419 
1420 
1421 static int __net_init arp_net_init(struct net *net)
1422 {
1423         if (!proc_create("arp", S_IRUGO, net->proc_net, &arp_seq_fops))
1424                 return -ENOMEM;
1425         return 0;
1426 }
1427 
1428 static void __net_exit arp_net_exit(struct net *net)
1429 {
1430         remove_proc_entry("arp", net->proc_net);
1431 }
1432 
1433 static struct pernet_operations arp_net_ops = {
1434         .init = arp_net_init,
1435         .exit = arp_net_exit,
1436 };
1437 
1438 static int __init arp_proc_init(void)
1439 {
1440         return register_pernet_subsys(&arp_net_ops);
1441 }
1442 
1443 #else /* CONFIG_PROC_FS */
1444 
1445 static int __init arp_proc_init(void)
1446 {
1447         return 0;
1448 }
1449 
1450 #endif /* CONFIG_PROC_FS */
1451 

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