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Linux/net/ipv4/arp.c

  1 /* linux/net/ipv4/arp.c
  2  *
  3  * Copyright (C) 1994 by Florian  La Roche
  4  *
  5  * This module implements the Address Resolution Protocol ARP (RFC 826),
  6  * which is used to convert IP addresses (or in the future maybe other
  7  * high-level addresses) into a low-level hardware address (like an Ethernet
  8  * address).
  9  *
 10  * This program is free software; you can redistribute it and/or
 11  * modify it under the terms of the GNU General Public License
 12  * as published by the Free Software Foundation; either version
 13  * 2 of the License, or (at your option) any later version.
 14  *
 15  * Fixes:
 16  *              Alan Cox        :       Removed the Ethernet assumptions in
 17  *                                      Florian's code
 18  *              Alan Cox        :       Fixed some small errors in the ARP
 19  *                                      logic
 20  *              Alan Cox        :       Allow >4K in /proc
 21  *              Alan Cox        :       Make ARP add its own protocol entry
 22  *              Ross Martin     :       Rewrote arp_rcv() and arp_get_info()
 23  *              Stephen Henson  :       Add AX25 support to arp_get_info()
 24  *              Alan Cox        :       Drop data when a device is downed.
 25  *              Alan Cox        :       Use init_timer().
 26  *              Alan Cox        :       Double lock fixes.
 27  *              Martin Seine    :       Move the arphdr structure
 28  *                                      to if_arp.h for compatibility.
 29  *                                      with BSD based programs.
 30  *              Andrew Tridgell :       Added ARP netmask code and
 31  *                                      re-arranged proxy handling.
 32  *              Alan Cox        :       Changed to use notifiers.
 33  *              Niibe Yutaka    :       Reply for this device or proxies only.
 34  *              Alan Cox        :       Don't proxy across hardware types!
 35  *              Jonathan Naylor :       Added support for NET/ROM.
 36  *              Mike Shaver     :       RFC1122 checks.
 37  *              Jonathan Naylor :       Only lookup the hardware address for
 38  *                                      the correct hardware type.
 39  *              Germano Caronni :       Assorted subtle races.
 40  *              Craig Schlenter :       Don't modify permanent entry
 41  *                                      during arp_rcv.
 42  *              Russ Nelson     :       Tidied up a few bits.
 43  *              Alexey Kuznetsov:       Major changes to caching and behaviour,
 44  *                                      eg intelligent arp probing and
 45  *                                      generation
 46  *                                      of host down events.
 47  *              Alan Cox        :       Missing unlock in device events.
 48  *              Eckes           :       ARP ioctl control errors.
 49  *              Alexey Kuznetsov:       Arp free fix.
 50  *              Manuel Rodriguez:       Gratuitous ARP.
 51  *              Jonathan Layes  :       Added arpd support through kerneld
 52  *                                      message queue (960314)
 53  *              Mike Shaver     :       /proc/sys/net/ipv4/arp_* support
 54  *              Mike McLagan    :       Routing by source
 55  *              Stuart Cheshire :       Metricom and grat arp fixes
 56  *                                      *** FOR 2.1 clean this up ***
 57  *              Lawrence V. Stefani: (08/12/96) Added FDDI support.
 58  *              Alan Cox        :       Took the AP1000 nasty FDDI hack and
 59  *                                      folded into the mainstream FDDI code.
 60  *                                      Ack spit, Linus how did you allow that
 61  *                                      one in...
 62  *              Jes Sorensen    :       Make FDDI work again in 2.1.x and
 63  *                                      clean up the APFDDI & gen. FDDI bits.
 64  *              Alexey Kuznetsov:       new arp state machine;
 65  *                                      now it is in net/core/neighbour.c.
 66  *              Krzysztof Halasa:       Added Frame Relay ARP support.
 67  *              Arnaldo C. Melo :       convert /proc/net/arp to seq_file
 68  *              Shmulik Hen:            Split arp_send to arp_create and
 69  *                                      arp_xmit so intermediate drivers like
 70  *                                      bonding can change the skb before
 71  *                                      sending (e.g. insert 8021q tag).
 72  *              Harald Welte    :       convert to make use of jenkins hash
 73  *              Jesper D. Brouer:       Proxy ARP PVLAN RFC 3069 support.
 74  */
 75 
 76 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 77 
 78 #include <linux/module.h>
 79 #include <linux/types.h>
 80 #include <linux/string.h>
 81 #include <linux/kernel.h>
 82 #include <linux/capability.h>
 83 #include <linux/socket.h>
 84 #include <linux/sockios.h>
 85 #include <linux/errno.h>
 86 #include <linux/in.h>
 87 #include <linux/mm.h>
 88 #include <linux/inet.h>
 89 #include <linux/inetdevice.h>
 90 #include <linux/netdevice.h>
 91 #include <linux/etherdevice.h>
 92 #include <linux/fddidevice.h>
 93 #include <linux/if_arp.h>
 94 #include <linux/skbuff.h>
 95 #include <linux/proc_fs.h>
 96 #include <linux/seq_file.h>
 97 #include <linux/stat.h>
 98 #include <linux/init.h>
 99 #include <linux/net.h>
100 #include <linux/rcupdate.h>
101 #include <linux/slab.h>
102 #ifdef CONFIG_SYSCTL
103 #include <linux/sysctl.h>
104 #endif
105 
106 #include <net/net_namespace.h>
107 #include <net/ip.h>
108 #include <net/icmp.h>
109 #include <net/route.h>
110 #include <net/protocol.h>
111 #include <net/tcp.h>
112 #include <net/sock.h>
113 #include <net/arp.h>
114 #include <net/ax25.h>
115 #include <net/netrom.h>
116 
117 #include <linux/uaccess.h>
118 
119 #include <linux/netfilter_arp.h>
120 
121 /*
122  *      Interface to generic neighbour cache.
123  */
124 static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd);
125 static 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                 .reachable_time         = 30 * HZ,
170                 .data   = {
171                         [NEIGH_VAR_MCAST_PROBES] = 3,
172                         [NEIGH_VAR_UCAST_PROBES] = 3,
173                         [NEIGH_VAR_RETRANS_TIME] = 1 * HZ,
174                         [NEIGH_VAR_BASE_REACHABLE_TIME] = 30 * HZ,
175                         [NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ,
176                         [NEIGH_VAR_GC_STALETIME] = 60 * HZ,
177                         [NEIGH_VAR_QUEUE_LEN_BYTES] = 64 * 1024,
178                         [NEIGH_VAR_PROXY_QLEN] = 64,
179                         [NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ,
180                         [NEIGH_VAR_PROXY_DELAY] = (8 * HZ) / 10,
181                         [NEIGH_VAR_LOCKTIME] = 1 * HZ,
182                 },
183         },
184         .gc_interval    = 30 * HZ,
185         .gc_thresh1     = 128,
186         .gc_thresh2     = 512,
187         .gc_thresh3     = 1024,
188 };
189 EXPORT_SYMBOL(arp_tbl);
190 
191 int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir)
192 {
193         switch (dev->type) {
194         case ARPHRD_ETHER:
195         case ARPHRD_FDDI:
196         case ARPHRD_IEEE802:
197                 ip_eth_mc_map(addr, haddr);
198                 return 0;
199         case ARPHRD_INFINIBAND:
200                 ip_ib_mc_map(addr, dev->broadcast, haddr);
201                 return 0;
202         case ARPHRD_IPGRE:
203                 ip_ipgre_mc_map(addr, dev->broadcast, haddr);
204                 return 0;
205         default:
206                 if (dir) {
207                         memcpy(haddr, dev->broadcast, dev->addr_len);
208                         return 0;
209                 }
210         }
211         return -EINVAL;
212 }
213 
214 
215 static u32 arp_hash(const void *pkey,
216                     const struct net_device *dev,
217                     __u32 *hash_rnd)
218 {
219         return arp_hashfn(*(u32 *)pkey, dev, *hash_rnd);
220 }
221 
222 static int arp_constructor(struct neighbour *neigh)
223 {
224         __be32 addr = *(__be32 *)neigh->primary_key;
225         struct net_device *dev = neigh->dev;
226         struct in_device *in_dev;
227         struct neigh_parms *parms;
228 
229         rcu_read_lock();
230         in_dev = __in_dev_get_rcu(dev);
231         if (in_dev == NULL) {
232                 rcu_read_unlock();
233                 return -EINVAL;
234         }
235 
236         neigh->type = inet_addr_type(dev_net(dev), addr);
237 
238         parms = in_dev->arp_parms;
239         __neigh_parms_put(neigh->parms);
240         neigh->parms = neigh_parms_clone(parms);
241         rcu_read_unlock();
242 
243         if (!dev->header_ops) {
244                 neigh->nud_state = NUD_NOARP;
245                 neigh->ops = &arp_direct_ops;
246                 neigh->output = neigh_direct_output;
247         } else {
248                 /* Good devices (checked by reading texts, but only Ethernet is
249                    tested)
250 
251                    ARPHRD_ETHER: (ethernet, apfddi)
252                    ARPHRD_FDDI: (fddi)
253                    ARPHRD_IEEE802: (tr)
254                    ARPHRD_METRICOM: (strip)
255                    ARPHRD_ARCNET:
256                    etc. etc. etc.
257 
258                    ARPHRD_IPDDP will also work, if author repairs it.
259                    I did not it, because this driver does not work even
260                    in old paradigm.
261                  */
262 
263 #if 1
264                 /* So... these "amateur" devices are hopeless.
265                    The only thing, that I can say now:
266                    It is very sad that we need to keep ugly obsolete
267                    code to make them happy.
268 
269                    They should be moved to more reasonable state, now
270                    they use rebuild_header INSTEAD OF hard_start_xmit!!!
271                    Besides that, they are sort of out of date
272                    (a lot of redundant clones/copies, useless in 2.1),
273                    I wonder why people believe that they work.
274                  */
275                 switch (dev->type) {
276                 default:
277                         break;
278                 case ARPHRD_ROSE:
279 #if IS_ENABLED(CONFIG_AX25)
280                 case ARPHRD_AX25:
281 #if IS_ENABLED(CONFIG_NETROM)
282                 case ARPHRD_NETROM:
283 #endif
284                         neigh->ops = &arp_broken_ops;
285                         neigh->output = neigh->ops->output;
286                         return 0;
287 #else
288                         break;
289 #endif
290                 }
291 #endif
292                 if (neigh->type == RTN_MULTICAST) {
293                         neigh->nud_state = NUD_NOARP;
294                         arp_mc_map(addr, neigh->ha, dev, 1);
295                 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) {
296                         neigh->nud_state = NUD_NOARP;
297                         memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
298                 } else if (neigh->type == RTN_BROADCAST ||
299                            (dev->flags & IFF_POINTOPOINT)) {
300                         neigh->nud_state = NUD_NOARP;
301                         memcpy(neigh->ha, dev->broadcast, dev->addr_len);
302                 }
303 
304                 if (dev->header_ops->cache)
305                         neigh->ops = &arp_hh_ops;
306                 else
307                         neigh->ops = &arp_generic_ops;
308 
309                 if (neigh->nud_state & NUD_VALID)
310                         neigh->output = neigh->ops->connected_output;
311                 else
312                         neigh->output = neigh->ops->output;
313         }
314         return 0;
315 }
316 
317 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
318 {
319         dst_link_failure(skb);
320         kfree_skb(skb);
321 }
322 
323 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
324 {
325         __be32 saddr = 0;
326         u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL;
327         struct net_device *dev = neigh->dev;
328         __be32 target = *(__be32 *)neigh->primary_key;
329         int probes = atomic_read(&neigh->probes);
330         struct in_device *in_dev;
331 
332         rcu_read_lock();
333         in_dev = __in_dev_get_rcu(dev);
334         if (!in_dev) {
335                 rcu_read_unlock();
336                 return;
337         }
338         switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
339         default:
340         case 0:         /* By default announce any local IP */
341                 if (skb && inet_addr_type(dev_net(dev),
342                                           ip_hdr(skb)->saddr) == RTN_LOCAL)
343                         saddr = ip_hdr(skb)->saddr;
344                 break;
345         case 1:         /* Restrict announcements of saddr in same subnet */
346                 if (!skb)
347                         break;
348                 saddr = ip_hdr(skb)->saddr;
349                 if (inet_addr_type(dev_net(dev), saddr) == RTN_LOCAL) {
350                         /* saddr should be known to target */
351                         if (inet_addr_onlink(in_dev, target, saddr))
352                                 break;
353                 }
354                 saddr = 0;
355                 break;
356         case 2:         /* Avoid secondary IPs, get a primary/preferred one */
357                 break;
358         }
359         rcu_read_unlock();
360 
361         if (!saddr)
362                 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
363 
364         probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES);
365         if (probes < 0) {
366                 if (!(neigh->nud_state & NUD_VALID))
367                         pr_debug("trying to ucast probe in NUD_INVALID\n");
368                 neigh_ha_snapshot(dst_ha, neigh, dev);
369                 dst_hw = dst_ha;
370         } else {
371                 probes -= NEIGH_VAR(neigh->parms, APP_PROBES);
372                 if (probes < 0) {
373                         neigh_app_ns(neigh);
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         struct net *net = dev_net(in_dev->dev);
385         int scope;
386 
387         switch (IN_DEV_ARP_IGNORE(in_dev)) {
388         case 0: /* Reply, the tip is already validated */
389                 return 0;
390         case 1: /* Reply only if tip is configured on the incoming interface */
391                 sip = 0;
392                 scope = RT_SCOPE_HOST;
393                 break;
394         case 2: /*
395                  * Reply only if tip is configured on the incoming interface
396                  * and is in same subnet as sip
397                  */
398                 scope = RT_SCOPE_HOST;
399                 break;
400         case 3: /* Do not reply for scope host addresses */
401                 sip = 0;
402                 scope = RT_SCOPE_LINK;
403                 in_dev = NULL;
404                 break;
405         case 4: /* Reserved */
406         case 5:
407         case 6:
408         case 7:
409                 return 0;
410         case 8: /* Do not reply */
411                 return 1;
412         default:
413                 return 0;
414         }
415         return !inet_confirm_addr(net, in_dev, sip, tip, scope);
416 }
417 
418 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
419 {
420         struct rtable *rt;
421         int flag = 0;
422         /*unsigned long now; */
423         struct net *net = dev_net(dev);
424 
425         rt = ip_route_output(net, sip, tip, 0, 0);
426         if (IS_ERR(rt))
427                 return 1;
428         if (rt->dst.dev != dev) {
429                 NET_INC_STATS_BH(net, LINUX_MIB_ARPFILTER);
430                 flag = 1;
431         }
432         ip_rt_put(rt);
433         return flag;
434 }
435 
436 /* OBSOLETE FUNCTIONS */
437 
438 /*
439  *      Find an arp mapping in the cache. If not found, post a request.
440  *
441  *      It is very UGLY routine: it DOES NOT use skb->dst->neighbour,
442  *      even if it exists. It is supposed that skb->dev was mangled
443  *      by a virtual device (eql, shaper). Nobody but broken devices
444  *      is allowed to use this function, it is scheduled to be removed. --ANK
445  */
446 
447 static int arp_set_predefined(int addr_hint, unsigned char *haddr,
448                               __be32 paddr, struct net_device *dev)
449 {
450         switch (addr_hint) {
451         case RTN_LOCAL:
452                 pr_debug("arp called for own IP address\n");
453                 memcpy(haddr, dev->dev_addr, dev->addr_len);
454                 return 1;
455         case RTN_MULTICAST:
456                 arp_mc_map(paddr, haddr, dev, 1);
457                 return 1;
458         case RTN_BROADCAST:
459                 memcpy(haddr, dev->broadcast, dev->addr_len);
460                 return 1;
461         }
462         return 0;
463 }
464 
465 
466 int arp_find(unsigned char *haddr, struct sk_buff *skb)
467 {
468         struct net_device *dev = skb->dev;
469         __be32 paddr;
470         struct neighbour *n;
471 
472         if (!skb_dst(skb)) {
473                 pr_debug("arp_find is called with dst==NULL\n");
474                 kfree_skb(skb);
475                 return 1;
476         }
477 
478         paddr = rt_nexthop(skb_rtable(skb), ip_hdr(skb)->daddr);
479         if (arp_set_predefined(inet_addr_type(dev_net(dev), paddr), haddr,
480                                paddr, dev))
481                 return 0;
482 
483         n = __neigh_lookup(&arp_tbl, &paddr, dev, 1);
484 
485         if (n) {
486                 n->used = jiffies;
487                 if (n->nud_state & NUD_VALID || neigh_event_send(n, skb) == 0) {
488                         neigh_ha_snapshot(haddr, n, dev);
489                         neigh_release(n);
490                         return 0;
491                 }
492                 neigh_release(n);
493         } else
494                 kfree_skb(skb);
495         return 1;
496 }
497 EXPORT_SYMBOL(arp_find);
498 
499 /* END OF OBSOLETE FUNCTIONS */
500 
501 /*
502  * Check if we can use proxy ARP for this path
503  */
504 static inline int arp_fwd_proxy(struct in_device *in_dev,
505                                 struct net_device *dev, struct rtable *rt)
506 {
507         struct in_device *out_dev;
508         int imi, omi = -1;
509 
510         if (rt->dst.dev == dev)
511                 return 0;
512 
513         if (!IN_DEV_PROXY_ARP(in_dev))
514                 return 0;
515         imi = IN_DEV_MEDIUM_ID(in_dev);
516         if (imi == 0)
517                 return 1;
518         if (imi == -1)
519                 return 0;
520 
521         /* place to check for proxy_arp for routes */
522 
523         out_dev = __in_dev_get_rcu(rt->dst.dev);
524         if (out_dev)
525                 omi = IN_DEV_MEDIUM_ID(out_dev);
526 
527         return omi != imi && omi != -1;
528 }
529 
530 /*
531  * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
532  *
533  * RFC3069 supports proxy arp replies back to the same interface.  This
534  * is done to support (ethernet) switch features, like RFC 3069, where
535  * the individual ports are not allowed to communicate with each
536  * other, BUT they are allowed to talk to the upstream router.  As
537  * described in RFC 3069, it is possible to allow these hosts to
538  * communicate through the upstream router, by proxy_arp'ing.
539  *
540  * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
541  *
542  *  This technology is known by different names:
543  *    In RFC 3069 it is called VLAN Aggregation.
544  *    Cisco and Allied Telesyn call it Private VLAN.
545  *    Hewlett-Packard call it Source-Port filtering or port-isolation.
546  *    Ericsson call it MAC-Forced Forwarding (RFC Draft).
547  *
548  */
549 static inline int arp_fwd_pvlan(struct in_device *in_dev,
550                                 struct net_device *dev, struct rtable *rt,
551                                 __be32 sip, __be32 tip)
552 {
553         /* Private VLAN is only concerned about the same ethernet segment */
554         if (rt->dst.dev != dev)
555                 return 0;
556 
557         /* Don't reply on self probes (often done by windowz boxes)*/
558         if (sip == tip)
559                 return 0;
560 
561         if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
562                 return 1;
563         else
564                 return 0;
565 }
566 
567 /*
568  *      Interface to link layer: send routine and receive handler.
569  */
570 
571 /*
572  *      Create an arp packet. If (dest_hw == NULL), we create a broadcast
573  *      message.
574  */
575 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
576                            struct net_device *dev, __be32 src_ip,
577                            const unsigned char *dest_hw,
578                            const unsigned char *src_hw,
579                            const unsigned char *target_hw)
580 {
581         struct sk_buff *skb;
582         struct arphdr *arp;
583         unsigned char *arp_ptr;
584         int hlen = LL_RESERVED_SPACE(dev);
585         int tlen = dev->needed_tailroom;
586 
587         /*
588          *      Allocate a buffer
589          */
590 
591         skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
592         if (skb == NULL)
593                 return NULL;
594 
595         skb_reserve(skb, hlen);
596         skb_reset_network_header(skb);
597         arp = (struct arphdr *) skb_put(skb, arp_hdr_len(dev));
598         skb->dev = dev;
599         skb->protocol = htons(ETH_P_ARP);
600         if (src_hw == NULL)
601                 src_hw = dev->dev_addr;
602         if (dest_hw == NULL)
603                 dest_hw = dev->broadcast;
604 
605         /*
606          *      Fill the device header for the ARP frame
607          */
608         if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
609                 goto out;
610 
611         /*
612          * Fill out the arp protocol part.
613          *
614          * The arp hardware type should match the device type, except for FDDI,
615          * which (according to RFC 1390) should always equal 1 (Ethernet).
616          */
617         /*
618          *      Exceptions everywhere. AX.25 uses the AX.25 PID value not the
619          *      DIX code for the protocol. Make these device structure fields.
620          */
621         switch (dev->type) {
622         default:
623                 arp->ar_hrd = htons(dev->type);
624                 arp->ar_pro = htons(ETH_P_IP);
625                 break;
626 
627 #if IS_ENABLED(CONFIG_AX25)
628         case ARPHRD_AX25:
629                 arp->ar_hrd = htons(ARPHRD_AX25);
630                 arp->ar_pro = htons(AX25_P_IP);
631                 break;
632 
633 #if IS_ENABLED(CONFIG_NETROM)
634         case ARPHRD_NETROM:
635                 arp->ar_hrd = htons(ARPHRD_NETROM);
636                 arp->ar_pro = htons(AX25_P_IP);
637                 break;
638 #endif
639 #endif
640 
641 #if IS_ENABLED(CONFIG_FDDI)
642         case ARPHRD_FDDI:
643                 arp->ar_hrd = htons(ARPHRD_ETHER);
644                 arp->ar_pro = htons(ETH_P_IP);
645                 break;
646 #endif
647         }
648 
649         arp->ar_hln = dev->addr_len;
650         arp->ar_pln = 4;
651         arp->ar_op = htons(type);
652 
653         arp_ptr = (unsigned char *)(arp + 1);
654 
655         memcpy(arp_ptr, src_hw, dev->addr_len);
656         arp_ptr += dev->addr_len;
657         memcpy(arp_ptr, &src_ip, 4);
658         arp_ptr += 4;
659 
660         switch (dev->type) {
661 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
662         case ARPHRD_IEEE1394:
663                 break;
664 #endif
665         default:
666                 if (target_hw != NULL)
667                         memcpy(arp_ptr, target_hw, dev->addr_len);
668                 else
669                         memset(arp_ptr, 0, dev->addr_len);
670                 arp_ptr += dev->addr_len;
671         }
672         memcpy(arp_ptr, &dest_ip, 4);
673 
674         return skb;
675 
676 out:
677         kfree_skb(skb);
678         return NULL;
679 }
680 EXPORT_SYMBOL(arp_create);
681 
682 /*
683  *      Send an arp packet.
684  */
685 void arp_xmit(struct sk_buff *skb)
686 {
687         /* Send it off, maybe filter it using firewalling first.  */
688         NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, skb, NULL, skb->dev, dev_queue_xmit);
689 }
690 EXPORT_SYMBOL(arp_xmit);
691 
692 /*
693  *      Create and send an arp packet.
694  */
695 void arp_send(int type, int ptype, __be32 dest_ip,
696               struct net_device *dev, __be32 src_ip,
697               const unsigned char *dest_hw, const unsigned char *src_hw,
698               const unsigned char *target_hw)
699 {
700         struct sk_buff *skb;
701 
702         /*
703          *      No arp on this interface.
704          */
705 
706         if (dev->flags&IFF_NOARP)
707                 return;
708 
709         skb = arp_create(type, ptype, dest_ip, dev, src_ip,
710                          dest_hw, src_hw, target_hw);
711         if (skb == NULL)
712                 return;
713 
714         arp_xmit(skb);
715 }
716 EXPORT_SYMBOL(arp_send);
717 
718 /*
719  *      Process an arp request.
720  */
721 
722 static int arp_process(struct sk_buff *skb)
723 {
724         struct net_device *dev = skb->dev;
725         struct in_device *in_dev = __in_dev_get_rcu(dev);
726         struct arphdr *arp;
727         unsigned char *arp_ptr;
728         struct rtable *rt;
729         unsigned char *sha;
730         __be32 sip, tip;
731         u16 dev_type = dev->type;
732         int addr_type;
733         struct neighbour *n;
734         struct net *net = dev_net(dev);
735         bool is_garp = false;
736 
737         /* arp_rcv below verifies the ARP header and verifies the device
738          * is ARP'able.
739          */
740 
741         if (in_dev == NULL)
742                 goto out;
743 
744         arp = arp_hdr(skb);
745 
746         switch (dev_type) {
747         default:
748                 if (arp->ar_pro != htons(ETH_P_IP) ||
749                     htons(dev_type) != arp->ar_hrd)
750                         goto out;
751                 break;
752         case ARPHRD_ETHER:
753         case ARPHRD_FDDI:
754         case ARPHRD_IEEE802:
755                 /*
756                  * ETHERNET, and Fibre Channel (which are IEEE 802
757                  * devices, according to RFC 2625) devices will accept ARP
758                  * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
759                  * This is the case also of FDDI, where the RFC 1390 says that
760                  * FDDI devices should accept ARP hardware of (1) Ethernet,
761                  * however, to be more robust, we'll accept both 1 (Ethernet)
762                  * or 6 (IEEE 802.2)
763                  */
764                 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
765                      arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
766                     arp->ar_pro != htons(ETH_P_IP))
767                         goto out;
768                 break;
769         case ARPHRD_AX25:
770                 if (arp->ar_pro != htons(AX25_P_IP) ||
771                     arp->ar_hrd != htons(ARPHRD_AX25))
772                         goto out;
773                 break;
774         case ARPHRD_NETROM:
775                 if (arp->ar_pro != htons(AX25_P_IP) ||
776                     arp->ar_hrd != htons(ARPHRD_NETROM))
777                         goto out;
778                 break;
779         }
780 
781         /* Understand only these message types */
782 
783         if (arp->ar_op != htons(ARPOP_REPLY) &&
784             arp->ar_op != htons(ARPOP_REQUEST))
785                 goto out;
786 
787 /*
788  *      Extract fields
789  */
790         arp_ptr = (unsigned char *)(arp + 1);
791         sha     = arp_ptr;
792         arp_ptr += dev->addr_len;
793         memcpy(&sip, arp_ptr, 4);
794         arp_ptr += 4;
795         switch (dev_type) {
796 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
797         case ARPHRD_IEEE1394:
798                 break;
799 #endif
800         default:
801                 arp_ptr += dev->addr_len;
802         }
803         memcpy(&tip, arp_ptr, 4);
804 /*
805  *      Check for bad requests for 127.x.x.x and requests for multicast
806  *      addresses.  If this is one such, delete it.
807  */
808         if (ipv4_is_multicast(tip) ||
809             (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip)))
810                 goto out;
811 
812 /*
813  *     Special case: We must set Frame Relay source Q.922 address
814  */
815         if (dev_type == ARPHRD_DLCI)
816                 sha = dev->broadcast;
817 
818 /*
819  *  Process entry.  The idea here is we want to send a reply if it is a
820  *  request for us or if it is a request for someone else that we hold
821  *  a proxy for.  We want to add an entry to our cache if it is a reply
822  *  to us or if it is a request for our address.
823  *  (The assumption for this last is that if someone is requesting our
824  *  address, they are probably intending to talk to us, so it saves time
825  *  if we cache their address.  Their address is also probably not in
826  *  our cache, since ours is not in their cache.)
827  *
828  *  Putting this another way, we only care about replies if they are to
829  *  us, in which case we add them to the cache.  For requests, we care
830  *  about those for us and those for our proxies.  We reply to both,
831  *  and in the case of requests for us we add the requester to the arp
832  *  cache.
833  */
834 
835         /* Special case: IPv4 duplicate address detection packet (RFC2131) */
836         if (sip == 0) {
837                 if (arp->ar_op == htons(ARPOP_REQUEST) &&
838                     inet_addr_type(net, tip) == RTN_LOCAL &&
839                     !arp_ignore(in_dev, sip, tip))
840                         arp_send(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, sha,
841                                  dev->dev_addr, sha);
842                 goto out;
843         }
844 
845         if (arp->ar_op == htons(ARPOP_REQUEST) &&
846             ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
847 
848                 rt = skb_rtable(skb);
849                 addr_type = rt->rt_type;
850 
851                 if (addr_type == RTN_LOCAL) {
852                         int dont_send;
853 
854                         dont_send = arp_ignore(in_dev, sip, tip);
855                         if (!dont_send && IN_DEV_ARPFILTER(in_dev))
856                                 dont_send = arp_filter(sip, tip, dev);
857                         if (!dont_send) {
858                                 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
859                                 if (n) {
860                                         arp_send(ARPOP_REPLY, ETH_P_ARP, sip,
861                                                  dev, tip, sha, dev->dev_addr,
862                                                  sha);
863                                         neigh_release(n);
864                                 }
865                         }
866                         goto out;
867                 } else if (IN_DEV_FORWARD(in_dev)) {
868                         if (addr_type == RTN_UNICAST  &&
869                             (arp_fwd_proxy(in_dev, dev, rt) ||
870                              arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
871                              (rt->dst.dev != dev &&
872                               pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
873                                 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
874                                 if (n)
875                                         neigh_release(n);
876 
877                                 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
878                                     skb->pkt_type == PACKET_HOST ||
879                                     NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) {
880                                         arp_send(ARPOP_REPLY, ETH_P_ARP, sip,
881                                                  dev, tip, sha, dev->dev_addr,
882                                                  sha);
883                                 } else {
884                                         pneigh_enqueue(&arp_tbl,
885                                                        in_dev->arp_parms, skb);
886                                         return 0;
887                                 }
888                                 goto out;
889                         }
890                 }
891         }
892 
893         /* Update our ARP tables */
894 
895         n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
896 
897         if (IN_DEV_ARP_ACCEPT(in_dev)) {
898                 /* Unsolicited ARP is not accepted by default.
899                    It is possible, that this option should be enabled for some
900                    devices (strip is candidate)
901                  */
902                 is_garp = arp->ar_op == htons(ARPOP_REQUEST) && tip == sip &&
903                           inet_addr_type(net, sip) == RTN_UNICAST;
904 
905                 if (n == NULL &&
906                     ((arp->ar_op == htons(ARPOP_REPLY)  &&
907                       inet_addr_type(net, sip) == RTN_UNICAST) || is_garp))
908                         n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
909         }
910 
911         if (n) {
912                 int state = NUD_REACHABLE;
913                 int override;
914 
915                 /* If several different ARP replies follows back-to-back,
916                    use the FIRST one. It is possible, if several proxy
917                    agents are active. Taking the first reply prevents
918                    arp trashing and chooses the fastest router.
919                  */
920                 override = time_after(jiffies,
921                                       n->updated +
922                                       NEIGH_VAR(n->parms, LOCKTIME)) ||
923                            is_garp;
924 
925                 /* Broadcast replies and request packets
926                    do not assert neighbour reachability.
927                  */
928                 if (arp->ar_op != htons(ARPOP_REPLY) ||
929                     skb->pkt_type != PACKET_HOST)
930                         state = NUD_STALE;
931                 neigh_update(n, sha, state,
932                              override ? NEIGH_UPDATE_F_OVERRIDE : 0);
933                 neigh_release(n);
934         }
935 
936 out:
937         consume_skb(skb);
938         return 0;
939 }
940 
941 static void parp_redo(struct sk_buff *skb)
942 {
943         arp_process(skb);
944 }
945 
946 
947 /*
948  *      Receive an arp request from the device layer.
949  */
950 
951 static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
952                    struct packet_type *pt, struct net_device *orig_dev)
953 {
954         const struct arphdr *arp;
955 
956         if (dev->flags & IFF_NOARP ||
957             skb->pkt_type == PACKET_OTHERHOST ||
958             skb->pkt_type == PACKET_LOOPBACK)
959                 goto freeskb;
960 
961         skb = skb_share_check(skb, GFP_ATOMIC);
962         if (!skb)
963                 goto out_of_mem;
964 
965         /* ARP header, plus 2 device addresses, plus 2 IP addresses.  */
966         if (!pskb_may_pull(skb, arp_hdr_len(dev)))
967                 goto freeskb;
968 
969         arp = arp_hdr(skb);
970         if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4)
971                 goto freeskb;
972 
973         memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
974 
975         return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, skb, dev, NULL, arp_process);
976 
977 freeskb:
978         kfree_skb(skb);
979 out_of_mem:
980         return 0;
981 }
982 
983 /*
984  *      User level interface (ioctl)
985  */
986 
987 /*
988  *      Set (create) an ARP cache entry.
989  */
990 
991 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
992 {
993         if (dev == NULL) {
994                 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
995                 return 0;
996         }
997         if (__in_dev_get_rtnl(dev)) {
998                 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
999                 return 0;
1000         }
1001         return -ENXIO;
1002 }
1003 
1004 static int arp_req_set_public(struct net *net, struct arpreq *r,
1005                 struct net_device *dev)
1006 {
1007         __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1008         __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1009 
1010         if (mask && mask != htonl(0xFFFFFFFF))
1011                 return -EINVAL;
1012         if (!dev && (r->arp_flags & ATF_COM)) {
1013                 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family,
1014                                       r->arp_ha.sa_data);
1015                 if (!dev)
1016                         return -ENODEV;
1017         }
1018         if (mask) {
1019                 if (pneigh_lookup(&arp_tbl, net, &ip, dev, 1) == NULL)
1020                         return -ENOBUFS;
1021                 return 0;
1022         }
1023 
1024         return arp_req_set_proxy(net, dev, 1);
1025 }
1026 
1027 static int arp_req_set(struct net *net, struct arpreq *r,
1028                        struct net_device *dev)
1029 {
1030         __be32 ip;
1031         struct neighbour *neigh;
1032         int err;
1033 
1034         if (r->arp_flags & ATF_PUBL)
1035                 return arp_req_set_public(net, r, dev);
1036 
1037         ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1038         if (r->arp_flags & ATF_PERM)
1039                 r->arp_flags |= ATF_COM;
1040         if (dev == NULL) {
1041                 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1042 
1043                 if (IS_ERR(rt))
1044                         return PTR_ERR(rt);
1045                 dev = rt->dst.dev;
1046                 ip_rt_put(rt);
1047                 if (!dev)
1048                         return -EINVAL;
1049         }
1050         switch (dev->type) {
1051 #if IS_ENABLED(CONFIG_FDDI)
1052         case ARPHRD_FDDI:
1053                 /*
1054                  * According to RFC 1390, FDDI devices should accept ARP
1055                  * hardware types of 1 (Ethernet).  However, to be more
1056                  * robust, we'll accept hardware types of either 1 (Ethernet)
1057                  * or 6 (IEEE 802.2).
1058                  */
1059                 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1060                     r->arp_ha.sa_family != ARPHRD_ETHER &&
1061                     r->arp_ha.sa_family != ARPHRD_IEEE802)
1062                         return -EINVAL;
1063                 break;
1064 #endif
1065         default:
1066                 if (r->arp_ha.sa_family != dev->type)
1067                         return -EINVAL;
1068                 break;
1069         }
1070 
1071         neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1072         err = PTR_ERR(neigh);
1073         if (!IS_ERR(neigh)) {
1074                 unsigned int state = NUD_STALE;
1075                 if (r->arp_flags & ATF_PERM)
1076                         state = NUD_PERMANENT;
1077                 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ?
1078                                    r->arp_ha.sa_data : NULL, state,
1079                                    NEIGH_UPDATE_F_OVERRIDE |
1080                                    NEIGH_UPDATE_F_ADMIN);
1081                 neigh_release(neigh);
1082         }
1083         return err;
1084 }
1085 
1086 static unsigned int arp_state_to_flags(struct neighbour *neigh)
1087 {
1088         if (neigh->nud_state&NUD_PERMANENT)
1089                 return ATF_PERM | ATF_COM;
1090         else if (neigh->nud_state&NUD_VALID)
1091                 return ATF_COM;
1092         else
1093                 return 0;
1094 }
1095 
1096 /*
1097  *      Get an ARP cache entry.
1098  */
1099 
1100 static int arp_req_get(struct arpreq *r, struct net_device *dev)
1101 {
1102         __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1103         struct neighbour *neigh;
1104         int err = -ENXIO;
1105 
1106         neigh = neigh_lookup(&arp_tbl, &ip, dev);
1107         if (neigh) {
1108                 read_lock_bh(&neigh->lock);
1109                 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
1110                 r->arp_flags = arp_state_to_flags(neigh);
1111                 read_unlock_bh(&neigh->lock);
1112                 r->arp_ha.sa_family = dev->type;
1113                 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1114                 neigh_release(neigh);
1115                 err = 0;
1116         }
1117         return err;
1118 }
1119 
1120 static int arp_invalidate(struct net_device *dev, __be32 ip)
1121 {
1122         struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
1123         int err = -ENXIO;
1124 
1125         if (neigh) {
1126                 if (neigh->nud_state & ~NUD_NOARP)
1127                         err = neigh_update(neigh, NULL, NUD_FAILED,
1128                                            NEIGH_UPDATE_F_OVERRIDE|
1129                                            NEIGH_UPDATE_F_ADMIN);
1130                 neigh_release(neigh);
1131         }
1132 
1133         return err;
1134 }
1135 
1136 static int arp_req_delete_public(struct net *net, struct arpreq *r,
1137                 struct net_device *dev)
1138 {
1139         __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1140         __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1141 
1142         if (mask == htonl(0xFFFFFFFF))
1143                 return pneigh_delete(&arp_tbl, net, &ip, dev);
1144 
1145         if (mask)
1146                 return -EINVAL;
1147 
1148         return arp_req_set_proxy(net, dev, 0);
1149 }
1150 
1151 static int arp_req_delete(struct net *net, struct arpreq *r,
1152                           struct net_device *dev)
1153 {
1154         __be32 ip;
1155 
1156         if (r->arp_flags & ATF_PUBL)
1157                 return arp_req_delete_public(net, r, dev);
1158 
1159         ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1160         if (dev == NULL) {
1161                 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1162                 if (IS_ERR(rt))
1163                         return PTR_ERR(rt);
1164                 dev = rt->dst.dev;
1165                 ip_rt_put(rt);
1166                 if (!dev)
1167                         return -EINVAL;
1168         }
1169         return arp_invalidate(dev, ip);
1170 }
1171 
1172 /*
1173  *      Handle an ARP layer I/O control request.
1174  */
1175 
1176 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1177 {
1178         int err;
1179         struct arpreq r;
1180         struct net_device *dev = NULL;
1181 
1182         switch (cmd) {
1183         case SIOCDARP:
1184         case SIOCSARP:
1185                 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1186                         return -EPERM;
1187         case SIOCGARP:
1188                 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1189                 if (err)
1190                         return -EFAULT;
1191                 break;
1192         default:
1193                 return -EINVAL;
1194         }
1195 
1196         if (r.arp_pa.sa_family != AF_INET)
1197                 return -EPFNOSUPPORT;
1198 
1199         if (!(r.arp_flags & ATF_PUBL) &&
1200             (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1201                 return -EINVAL;
1202         if (!(r.arp_flags & ATF_NETMASK))
1203                 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1204                                                            htonl(0xFFFFFFFFUL);
1205         rtnl_lock();
1206         if (r.arp_dev[0]) {
1207                 err = -ENODEV;
1208                 dev = __dev_get_by_name(net, r.arp_dev);
1209                 if (dev == NULL)
1210                         goto out;
1211 
1212                 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1213                 if (!r.arp_ha.sa_family)
1214                         r.arp_ha.sa_family = dev->type;
1215                 err = -EINVAL;
1216                 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1217                         goto out;
1218         } else if (cmd == SIOCGARP) {
1219                 err = -ENODEV;
1220                 goto out;
1221         }
1222 
1223         switch (cmd) {
1224         case SIOCDARP:
1225                 err = arp_req_delete(net, &r, dev);
1226                 break;
1227         case SIOCSARP:
1228                 err = arp_req_set(net, &r, dev);
1229                 break;
1230         case SIOCGARP:
1231                 err = arp_req_get(&r, dev);
1232                 break;
1233         }
1234 out:
1235         rtnl_unlock();
1236         if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
1237                 err = -EFAULT;
1238         return err;
1239 }
1240 
1241 static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1242                             void *ptr)
1243 {
1244         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
1245         struct netdev_notifier_change_info *change_info;
1246 
1247         switch (event) {
1248         case NETDEV_CHANGEADDR:
1249                 neigh_changeaddr(&arp_tbl, dev);
1250                 rt_cache_flush(dev_net(dev));
1251                 break;
1252         case NETDEV_CHANGE:
1253                 change_info = ptr;
1254                 if (change_info->flags_changed & IFF_NOARP)
1255                         neigh_changeaddr(&arp_tbl, dev);
1256                 break;
1257         default:
1258                 break;
1259         }
1260 
1261         return NOTIFY_DONE;
1262 }
1263 
1264 static struct notifier_block arp_netdev_notifier = {
1265         .notifier_call = arp_netdev_event,
1266 };
1267 
1268 /* Note, that it is not on notifier chain.
1269    It is necessary, that this routine was called after route cache will be
1270    flushed.
1271  */
1272 void arp_ifdown(struct net_device *dev)
1273 {
1274         neigh_ifdown(&arp_tbl, dev);
1275 }
1276 
1277 
1278 /*
1279  *      Called once on startup.
1280  */
1281 
1282 static struct packet_type arp_packet_type __read_mostly = {
1283         .type = cpu_to_be16(ETH_P_ARP),
1284         .func = arp_rcv,
1285 };
1286 
1287 static int arp_proc_init(void);
1288 
1289 void __init arp_init(void)
1290 {
1291         neigh_table_init(&arp_tbl);
1292 
1293         dev_add_pack(&arp_packet_type);
1294         arp_proc_init();
1295 #ifdef CONFIG_SYSCTL
1296         neigh_sysctl_register(NULL, &arp_tbl.parms, NULL);
1297 #endif
1298         register_netdevice_notifier(&arp_netdev_notifier);
1299 }
1300 
1301 #ifdef CONFIG_PROC_FS
1302 #if IS_ENABLED(CONFIG_AX25)
1303 
1304 /* ------------------------------------------------------------------------ */
1305 /*
1306  *      ax25 -> ASCII conversion
1307  */
1308 static char *ax2asc2(ax25_address *a, char *buf)
1309 {
1310         char c, *s;
1311         int n;
1312 
1313         for (n = 0, s = buf; n < 6; n++) {
1314                 c = (a->ax25_call[n] >> 1) & 0x7F;
1315 
1316                 if (c != ' ')
1317                         *s++ = c;
1318         }
1319 
1320         *s++ = '-';
1321         n = (a->ax25_call[6] >> 1) & 0x0F;
1322         if (n > 9) {
1323                 *s++ = '1';
1324                 n -= 10;
1325         }
1326 
1327         *s++ = n + '';
1328         *s++ = '\0';
1329 
1330         if (*buf == '\0' || *buf == '-')
1331                 return "*";
1332 
1333         return buf;
1334 }
1335 #endif /* CONFIG_AX25 */
1336 
1337 #define HBUFFERLEN 30
1338 
1339 static void arp_format_neigh_entry(struct seq_file *seq,
1340                                    struct neighbour *n)
1341 {
1342         char hbuffer[HBUFFERLEN];
1343         int k, j;
1344         char tbuf[16];
1345         struct net_device *dev = n->dev;
1346         int hatype = dev->type;
1347 
1348         read_lock(&n->lock);
1349         /* Convert hardware address to XX:XX:XX:XX ... form. */
1350 #if IS_ENABLED(CONFIG_AX25)
1351         if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1352                 ax2asc2((ax25_address *)n->ha, hbuffer);
1353         else {
1354 #endif
1355         for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1356                 hbuffer[k++] = hex_asc_hi(n->ha[j]);
1357                 hbuffer[k++] = hex_asc_lo(n->ha[j]);
1358                 hbuffer[k++] = ':';
1359         }
1360         if (k != 0)
1361                 --k;
1362         hbuffer[k] = 0;
1363 #if IS_ENABLED(CONFIG_AX25)
1364         }
1365 #endif
1366         sprintf(tbuf, "%pI4", n->primary_key);
1367         seq_printf(seq, "%-16s 0x%-10x0x%-10x%s     *        %s\n",
1368                    tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1369         read_unlock(&n->lock);
1370 }
1371 
1372 static void arp_format_pneigh_entry(struct seq_file *seq,
1373                                     struct pneigh_entry *n)
1374 {
1375         struct net_device *dev = n->dev;
1376         int hatype = dev ? dev->type : 0;
1377         char tbuf[16];
1378 
1379         sprintf(tbuf, "%pI4", n->key);
1380         seq_printf(seq, "%-16s 0x%-10x0x%-10x%s     *        %s\n",
1381                    tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1382                    dev ? dev->name : "*");
1383 }
1384 
1385 static int arp_seq_show(struct seq_file *seq, void *v)
1386 {
1387         if (v == SEQ_START_TOKEN) {
1388                 seq_puts(seq, "IP address       HW type     Flags       "
1389                               "HW address            Mask     Device\n");
1390         } else {
1391                 struct neigh_seq_state *state = seq->private;
1392 
1393                 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1394                         arp_format_pneigh_entry(seq, v);
1395                 else
1396                         arp_format_neigh_entry(seq, v);
1397         }
1398 
1399         return 0;
1400 }
1401 
1402 static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1403 {
1404         /* Don't want to confuse "arp -a" w/ magic entries,
1405          * so we tell the generic iterator to skip NUD_NOARP.
1406          */
1407         return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1408 }
1409 
1410 /* ------------------------------------------------------------------------ */
1411 
1412 static const struct seq_operations arp_seq_ops = {
1413         .start  = arp_seq_start,
1414         .next   = neigh_seq_next,
1415         .stop   = neigh_seq_stop,
1416         .show   = arp_seq_show,
1417 };
1418 
1419 static int arp_seq_open(struct inode *inode, struct file *file)
1420 {
1421         return seq_open_net(inode, file, &arp_seq_ops,
1422                             sizeof(struct neigh_seq_state));
1423 }
1424 
1425 static const struct file_operations arp_seq_fops = {
1426         .owner          = THIS_MODULE,
1427         .open           = arp_seq_open,
1428         .read           = seq_read,
1429         .llseek         = seq_lseek,
1430         .release        = seq_release_net,
1431 };
1432 
1433 
1434 static int __net_init arp_net_init(struct net *net)
1435 {
1436         if (!proc_create("arp", S_IRUGO, net->proc_net, &arp_seq_fops))
1437                 return -ENOMEM;
1438         return 0;
1439 }
1440 
1441 static void __net_exit arp_net_exit(struct net *net)
1442 {
1443         remove_proc_entry("arp", net->proc_net);
1444 }
1445 
1446 static struct pernet_operations arp_net_ops = {
1447         .init = arp_net_init,
1448         .exit = arp_net_exit,
1449 };
1450 
1451 static int __init arp_proc_init(void)
1452 {
1453         return register_pernet_subsys(&arp_net_ops);
1454 }
1455 
1456 #else /* CONFIG_PROC_FS */
1457 
1458 static int __init arp_proc_init(void)
1459 {
1460         return 0;
1461 }
1462 
1463 #endif /* CONFIG_PROC_FS */
1464 

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