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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 #include <net/dst_metadata.h>
117 #include <net/ip_tunnels.h>
118 
119 #include <linux/uaccess.h>
120 
121 #include <linux/netfilter_arp.h>
122 
123 /*
124  *      Interface to generic neighbour cache.
125  */
126 static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd);
127 static bool arp_key_eq(const struct neighbour *n, const void *pkey);
128 static int arp_constructor(struct neighbour *neigh);
129 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
130 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
131 static void parp_redo(struct sk_buff *skb);
132 
133 static const struct neigh_ops arp_generic_ops = {
134         .family =               AF_INET,
135         .solicit =              arp_solicit,
136         .error_report =         arp_error_report,
137         .output =               neigh_resolve_output,
138         .connected_output =     neigh_connected_output,
139 };
140 
141 static const struct neigh_ops arp_hh_ops = {
142         .family =               AF_INET,
143         .solicit =              arp_solicit,
144         .error_report =         arp_error_report,
145         .output =               neigh_resolve_output,
146         .connected_output =     neigh_resolve_output,
147 };
148 
149 static const struct neigh_ops arp_direct_ops = {
150         .family =               AF_INET,
151         .output =               neigh_direct_output,
152         .connected_output =     neigh_direct_output,
153 };
154 
155 struct neigh_table arp_tbl = {
156         .family         = AF_INET,
157         .key_len        = 4,
158         .protocol       = cpu_to_be16(ETH_P_IP),
159         .hash           = arp_hash,
160         .key_eq         = arp_key_eq,
161         .constructor    = arp_constructor,
162         .proxy_redo     = parp_redo,
163         .id             = "arp_cache",
164         .parms          = {
165                 .tbl                    = &arp_tbl,
166                 .reachable_time         = 30 * HZ,
167                 .data   = {
168                         [NEIGH_VAR_MCAST_PROBES] = 3,
169                         [NEIGH_VAR_UCAST_PROBES] = 3,
170                         [NEIGH_VAR_RETRANS_TIME] = 1 * HZ,
171                         [NEIGH_VAR_BASE_REACHABLE_TIME] = 30 * HZ,
172                         [NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ,
173                         [NEIGH_VAR_GC_STALETIME] = 60 * HZ,
174                         [NEIGH_VAR_QUEUE_LEN_BYTES] = SK_WMEM_MAX,
175                         [NEIGH_VAR_PROXY_QLEN] = 64,
176                         [NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ,
177                         [NEIGH_VAR_PROXY_DELAY] = (8 * HZ) / 10,
178                         [NEIGH_VAR_LOCKTIME] = 1 * HZ,
179                 },
180         },
181         .gc_interval    = 30 * HZ,
182         .gc_thresh1     = 128,
183         .gc_thresh2     = 512,
184         .gc_thresh3     = 1024,
185 };
186 EXPORT_SYMBOL(arp_tbl);
187 
188 int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir)
189 {
190         switch (dev->type) {
191         case ARPHRD_ETHER:
192         case ARPHRD_FDDI:
193         case ARPHRD_IEEE802:
194                 ip_eth_mc_map(addr, haddr);
195                 return 0;
196         case ARPHRD_INFINIBAND:
197                 ip_ib_mc_map(addr, dev->broadcast, haddr);
198                 return 0;
199         case ARPHRD_IPGRE:
200                 ip_ipgre_mc_map(addr, dev->broadcast, haddr);
201                 return 0;
202         default:
203                 if (dir) {
204                         memcpy(haddr, dev->broadcast, dev->addr_len);
205                         return 0;
206                 }
207         }
208         return -EINVAL;
209 }
210 
211 
212 static u32 arp_hash(const void *pkey,
213                     const struct net_device *dev,
214                     __u32 *hash_rnd)
215 {
216         return arp_hashfn(pkey, dev, hash_rnd);
217 }
218 
219 static bool arp_key_eq(const struct neighbour *neigh, const void *pkey)
220 {
221         return neigh_key_eq32(neigh, pkey);
222 }
223 
224 static int arp_constructor(struct neighbour *neigh)
225 {
226         __be32 addr;
227         struct net_device *dev = neigh->dev;
228         struct in_device *in_dev;
229         struct neigh_parms *parms;
230         u32 inaddr_any = INADDR_ANY;
231 
232         if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT))
233                 memcpy(neigh->primary_key, &inaddr_any, arp_tbl.key_len);
234 
235         addr = *(__be32 *)neigh->primary_key;
236         rcu_read_lock();
237         in_dev = __in_dev_get_rcu(dev);
238         if (!in_dev) {
239                 rcu_read_unlock();
240                 return -EINVAL;
241         }
242 
243         neigh->type = inet_addr_type_dev_table(dev_net(dev), dev, addr);
244 
245         parms = in_dev->arp_parms;
246         __neigh_parms_put(neigh->parms);
247         neigh->parms = neigh_parms_clone(parms);
248         rcu_read_unlock();
249 
250         if (!dev->header_ops) {
251                 neigh->nud_state = NUD_NOARP;
252                 neigh->ops = &arp_direct_ops;
253                 neigh->output = neigh_direct_output;
254         } else {
255                 /* Good devices (checked by reading texts, but only Ethernet is
256                    tested)
257 
258                    ARPHRD_ETHER: (ethernet, apfddi)
259                    ARPHRD_FDDI: (fddi)
260                    ARPHRD_IEEE802: (tr)
261                    ARPHRD_METRICOM: (strip)
262                    ARPHRD_ARCNET:
263                    etc. etc. etc.
264 
265                    ARPHRD_IPDDP will also work, if author repairs it.
266                    I did not it, because this driver does not work even
267                    in old paradigm.
268                  */
269 
270                 if (neigh->type == RTN_MULTICAST) {
271                         neigh->nud_state = NUD_NOARP;
272                         arp_mc_map(addr, neigh->ha, dev, 1);
273                 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) {
274                         neigh->nud_state = NUD_NOARP;
275                         memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
276                 } else if (neigh->type == RTN_BROADCAST ||
277                            (dev->flags & IFF_POINTOPOINT)) {
278                         neigh->nud_state = NUD_NOARP;
279                         memcpy(neigh->ha, dev->broadcast, dev->addr_len);
280                 }
281 
282                 if (dev->header_ops->cache)
283                         neigh->ops = &arp_hh_ops;
284                 else
285                         neigh->ops = &arp_generic_ops;
286 
287                 if (neigh->nud_state & NUD_VALID)
288                         neigh->output = neigh->ops->connected_output;
289                 else
290                         neigh->output = neigh->ops->output;
291         }
292         return 0;
293 }
294 
295 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
296 {
297         dst_link_failure(skb);
298         kfree_skb(skb);
299 }
300 
301 /* Create and send an arp packet. */
302 static void arp_send_dst(int type, int ptype, __be32 dest_ip,
303                          struct net_device *dev, __be32 src_ip,
304                          const unsigned char *dest_hw,
305                          const unsigned char *src_hw,
306                          const unsigned char *target_hw,
307                          struct dst_entry *dst)
308 {
309         struct sk_buff *skb;
310 
311         /* arp on this interface. */
312         if (dev->flags & IFF_NOARP)
313                 return;
314 
315         skb = arp_create(type, ptype, dest_ip, dev, src_ip,
316                          dest_hw, src_hw, target_hw);
317         if (!skb)
318                 return;
319 
320         skb_dst_set(skb, dst_clone(dst));
321         arp_xmit(skb);
322 }
323 
324 void arp_send(int type, int ptype, __be32 dest_ip,
325               struct net_device *dev, __be32 src_ip,
326               const unsigned char *dest_hw, const unsigned char *src_hw,
327               const unsigned char *target_hw)
328 {
329         arp_send_dst(type, ptype, dest_ip, dev, src_ip, dest_hw, src_hw,
330                      target_hw, NULL);
331 }
332 EXPORT_SYMBOL(arp_send);
333 
334 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
335 {
336         __be32 saddr = 0;
337         u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL;
338         struct net_device *dev = neigh->dev;
339         __be32 target = *(__be32 *)neigh->primary_key;
340         int probes = atomic_read(&neigh->probes);
341         struct in_device *in_dev;
342         struct dst_entry *dst = NULL;
343 
344         rcu_read_lock();
345         in_dev = __in_dev_get_rcu(dev);
346         if (!in_dev) {
347                 rcu_read_unlock();
348                 return;
349         }
350         switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
351         default:
352         case 0:         /* By default announce any local IP */
353                 if (skb && inet_addr_type_dev_table(dev_net(dev), dev,
354                                           ip_hdr(skb)->saddr) == RTN_LOCAL)
355                         saddr = ip_hdr(skb)->saddr;
356                 break;
357         case 1:         /* Restrict announcements of saddr in same subnet */
358                 if (!skb)
359                         break;
360                 saddr = ip_hdr(skb)->saddr;
361                 if (inet_addr_type_dev_table(dev_net(dev), dev,
362                                              saddr) == RTN_LOCAL) {
363                         /* saddr should be known to target */
364                         if (inet_addr_onlink(in_dev, target, saddr))
365                                 break;
366                 }
367                 saddr = 0;
368                 break;
369         case 2:         /* Avoid secondary IPs, get a primary/preferred one */
370                 break;
371         }
372         rcu_read_unlock();
373 
374         if (!saddr)
375                 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
376 
377         probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES);
378         if (probes < 0) {
379                 if (!(neigh->nud_state & NUD_VALID))
380                         pr_debug("trying to ucast probe in NUD_INVALID\n");
381                 neigh_ha_snapshot(dst_ha, neigh, dev);
382                 dst_hw = dst_ha;
383         } else {
384                 probes -= NEIGH_VAR(neigh->parms, APP_PROBES);
385                 if (probes < 0) {
386                         neigh_app_ns(neigh);
387                         return;
388                 }
389         }
390 
391         if (skb && !(dev->priv_flags & IFF_XMIT_DST_RELEASE))
392                 dst = skb_dst(skb);
393         arp_send_dst(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
394                      dst_hw, dev->dev_addr, NULL, dst);
395 }
396 
397 static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip)
398 {
399         struct net *net = dev_net(in_dev->dev);
400         int scope;
401 
402         switch (IN_DEV_ARP_IGNORE(in_dev)) {
403         case 0: /* Reply, the tip is already validated */
404                 return 0;
405         case 1: /* Reply only if tip is configured on the incoming interface */
406                 sip = 0;
407                 scope = RT_SCOPE_HOST;
408                 break;
409         case 2: /*
410                  * Reply only if tip is configured on the incoming interface
411                  * and is in same subnet as sip
412                  */
413                 scope = RT_SCOPE_HOST;
414                 break;
415         case 3: /* Do not reply for scope host addresses */
416                 sip = 0;
417                 scope = RT_SCOPE_LINK;
418                 in_dev = NULL;
419                 break;
420         case 4: /* Reserved */
421         case 5:
422         case 6:
423         case 7:
424                 return 0;
425         case 8: /* Do not reply */
426                 return 1;
427         default:
428                 return 0;
429         }
430         return !inet_confirm_addr(net, in_dev, sip, tip, scope);
431 }
432 
433 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
434 {
435         struct rtable *rt;
436         int flag = 0;
437         /*unsigned long now; */
438         struct net *net = dev_net(dev);
439 
440         rt = ip_route_output(net, sip, tip, 0, l3mdev_master_ifindex_rcu(dev));
441         if (IS_ERR(rt))
442                 return 1;
443         if (rt->dst.dev != dev) {
444                 __NET_INC_STATS(net, LINUX_MIB_ARPFILTER);
445                 flag = 1;
446         }
447         ip_rt_put(rt);
448         return flag;
449 }
450 
451 /*
452  * Check if we can use proxy ARP for this path
453  */
454 static inline int arp_fwd_proxy(struct in_device *in_dev,
455                                 struct net_device *dev, struct rtable *rt)
456 {
457         struct in_device *out_dev;
458         int imi, omi = -1;
459 
460         if (rt->dst.dev == dev)
461                 return 0;
462 
463         if (!IN_DEV_PROXY_ARP(in_dev))
464                 return 0;
465         imi = IN_DEV_MEDIUM_ID(in_dev);
466         if (imi == 0)
467                 return 1;
468         if (imi == -1)
469                 return 0;
470 
471         /* place to check for proxy_arp for routes */
472 
473         out_dev = __in_dev_get_rcu(rt->dst.dev);
474         if (out_dev)
475                 omi = IN_DEV_MEDIUM_ID(out_dev);
476 
477         return omi != imi && omi != -1;
478 }
479 
480 /*
481  * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
482  *
483  * RFC3069 supports proxy arp replies back to the same interface.  This
484  * is done to support (ethernet) switch features, like RFC 3069, where
485  * the individual ports are not allowed to communicate with each
486  * other, BUT they are allowed to talk to the upstream router.  As
487  * described in RFC 3069, it is possible to allow these hosts to
488  * communicate through the upstream router, by proxy_arp'ing.
489  *
490  * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
491  *
492  *  This technology is known by different names:
493  *    In RFC 3069 it is called VLAN Aggregation.
494  *    Cisco and Allied Telesyn call it Private VLAN.
495  *    Hewlett-Packard call it Source-Port filtering or port-isolation.
496  *    Ericsson call it MAC-Forced Forwarding (RFC Draft).
497  *
498  */
499 static inline int arp_fwd_pvlan(struct in_device *in_dev,
500                                 struct net_device *dev, struct rtable *rt,
501                                 __be32 sip, __be32 tip)
502 {
503         /* Private VLAN is only concerned about the same ethernet segment */
504         if (rt->dst.dev != dev)
505                 return 0;
506 
507         /* Don't reply on self probes (often done by windowz boxes)*/
508         if (sip == tip)
509                 return 0;
510 
511         if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
512                 return 1;
513         else
514                 return 0;
515 }
516 
517 /*
518  *      Interface to link layer: send routine and receive handler.
519  */
520 
521 /*
522  *      Create an arp packet. If dest_hw is not set, we create a broadcast
523  *      message.
524  */
525 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
526                            struct net_device *dev, __be32 src_ip,
527                            const unsigned char *dest_hw,
528                            const unsigned char *src_hw,
529                            const unsigned char *target_hw)
530 {
531         struct sk_buff *skb;
532         struct arphdr *arp;
533         unsigned char *arp_ptr;
534         int hlen = LL_RESERVED_SPACE(dev);
535         int tlen = dev->needed_tailroom;
536 
537         /*
538          *      Allocate a buffer
539          */
540 
541         skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
542         if (!skb)
543                 return NULL;
544 
545         skb_reserve(skb, hlen);
546         skb_reset_network_header(skb);
547         arp = skb_put(skb, arp_hdr_len(dev));
548         skb->dev = dev;
549         skb->protocol = htons(ETH_P_ARP);
550         if (!src_hw)
551                 src_hw = dev->dev_addr;
552         if (!dest_hw)
553                 dest_hw = dev->broadcast;
554 
555         /*
556          *      Fill the device header for the ARP frame
557          */
558         if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
559                 goto out;
560 
561         /*
562          * Fill out the arp protocol part.
563          *
564          * The arp hardware type should match the device type, except for FDDI,
565          * which (according to RFC 1390) should always equal 1 (Ethernet).
566          */
567         /*
568          *      Exceptions everywhere. AX.25 uses the AX.25 PID value not the
569          *      DIX code for the protocol. Make these device structure fields.
570          */
571         switch (dev->type) {
572         default:
573                 arp->ar_hrd = htons(dev->type);
574                 arp->ar_pro = htons(ETH_P_IP);
575                 break;
576 
577 #if IS_ENABLED(CONFIG_AX25)
578         case ARPHRD_AX25:
579                 arp->ar_hrd = htons(ARPHRD_AX25);
580                 arp->ar_pro = htons(AX25_P_IP);
581                 break;
582 
583 #if IS_ENABLED(CONFIG_NETROM)
584         case ARPHRD_NETROM:
585                 arp->ar_hrd = htons(ARPHRD_NETROM);
586                 arp->ar_pro = htons(AX25_P_IP);
587                 break;
588 #endif
589 #endif
590 
591 #if IS_ENABLED(CONFIG_FDDI)
592         case ARPHRD_FDDI:
593                 arp->ar_hrd = htons(ARPHRD_ETHER);
594                 arp->ar_pro = htons(ETH_P_IP);
595                 break;
596 #endif
597         }
598 
599         arp->ar_hln = dev->addr_len;
600         arp->ar_pln = 4;
601         arp->ar_op = htons(type);
602 
603         arp_ptr = (unsigned char *)(arp + 1);
604 
605         memcpy(arp_ptr, src_hw, dev->addr_len);
606         arp_ptr += dev->addr_len;
607         memcpy(arp_ptr, &src_ip, 4);
608         arp_ptr += 4;
609 
610         switch (dev->type) {
611 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
612         case ARPHRD_IEEE1394:
613                 break;
614 #endif
615         default:
616                 if (target_hw)
617                         memcpy(arp_ptr, target_hw, dev->addr_len);
618                 else
619                         memset(arp_ptr, 0, dev->addr_len);
620                 arp_ptr += dev->addr_len;
621         }
622         memcpy(arp_ptr, &dest_ip, 4);
623 
624         return skb;
625 
626 out:
627         kfree_skb(skb);
628         return NULL;
629 }
630 EXPORT_SYMBOL(arp_create);
631 
632 static int arp_xmit_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
633 {
634         return dev_queue_xmit(skb);
635 }
636 
637 /*
638  *      Send an arp packet.
639  */
640 void arp_xmit(struct sk_buff *skb)
641 {
642         /* Send it off, maybe filter it using firewalling first.  */
643         NF_HOOK(NFPROTO_ARP, NF_ARP_OUT,
644                 dev_net(skb->dev), NULL, skb, NULL, skb->dev,
645                 arp_xmit_finish);
646 }
647 EXPORT_SYMBOL(arp_xmit);
648 
649 static bool arp_is_garp(struct net *net, struct net_device *dev,
650                         int *addr_type, __be16 ar_op,
651                         __be32 sip, __be32 tip,
652                         unsigned char *sha, unsigned char *tha)
653 {
654         bool is_garp = tip == sip;
655 
656         /* Gratuitous ARP _replies_ also require target hwaddr to be
657          * the same as source.
658          */
659         if (is_garp && ar_op == htons(ARPOP_REPLY))
660                 is_garp =
661                         /* IPv4 over IEEE 1394 doesn't provide target
662                          * hardware address field in its ARP payload.
663                          */
664                         tha &&
665                         !memcmp(tha, sha, dev->addr_len);
666 
667         if (is_garp) {
668                 *addr_type = inet_addr_type_dev_table(net, dev, sip);
669                 if (*addr_type != RTN_UNICAST)
670                         is_garp = false;
671         }
672         return is_garp;
673 }
674 
675 /*
676  *      Process an arp request.
677  */
678 
679 static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb)
680 {
681         struct net_device *dev = skb->dev;
682         struct in_device *in_dev = __in_dev_get_rcu(dev);
683         struct arphdr *arp;
684         unsigned char *arp_ptr;
685         struct rtable *rt;
686         unsigned char *sha;
687         unsigned char *tha = NULL;
688         __be32 sip, tip;
689         u16 dev_type = dev->type;
690         int addr_type;
691         struct neighbour *n;
692         struct dst_entry *reply_dst = NULL;
693         bool is_garp = false;
694 
695         /* arp_rcv below verifies the ARP header and verifies the device
696          * is ARP'able.
697          */
698 
699         if (!in_dev)
700                 goto out_free_skb;
701 
702         arp = arp_hdr(skb);
703 
704         switch (dev_type) {
705         default:
706                 if (arp->ar_pro != htons(ETH_P_IP) ||
707                     htons(dev_type) != arp->ar_hrd)
708                         goto out_free_skb;
709                 break;
710         case ARPHRD_ETHER:
711         case ARPHRD_FDDI:
712         case ARPHRD_IEEE802:
713                 /*
714                  * ETHERNET, and Fibre Channel (which are IEEE 802
715                  * devices, according to RFC 2625) devices will accept ARP
716                  * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
717                  * This is the case also of FDDI, where the RFC 1390 says that
718                  * FDDI devices should accept ARP hardware of (1) Ethernet,
719                  * however, to be more robust, we'll accept both 1 (Ethernet)
720                  * or 6 (IEEE 802.2)
721                  */
722                 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
723                      arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
724                     arp->ar_pro != htons(ETH_P_IP))
725                         goto out_free_skb;
726                 break;
727         case ARPHRD_AX25:
728                 if (arp->ar_pro != htons(AX25_P_IP) ||
729                     arp->ar_hrd != htons(ARPHRD_AX25))
730                         goto out_free_skb;
731                 break;
732         case ARPHRD_NETROM:
733                 if (arp->ar_pro != htons(AX25_P_IP) ||
734                     arp->ar_hrd != htons(ARPHRD_NETROM))
735                         goto out_free_skb;
736                 break;
737         }
738 
739         /* Understand only these message types */
740 
741         if (arp->ar_op != htons(ARPOP_REPLY) &&
742             arp->ar_op != htons(ARPOP_REQUEST))
743                 goto out_free_skb;
744 
745 /*
746  *      Extract fields
747  */
748         arp_ptr = (unsigned char *)(arp + 1);
749         sha     = arp_ptr;
750         arp_ptr += dev->addr_len;
751         memcpy(&sip, arp_ptr, 4);
752         arp_ptr += 4;
753         switch (dev_type) {
754 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
755         case ARPHRD_IEEE1394:
756                 break;
757 #endif
758         default:
759                 tha = arp_ptr;
760                 arp_ptr += dev->addr_len;
761         }
762         memcpy(&tip, arp_ptr, 4);
763 /*
764  *      Check for bad requests for 127.x.x.x and requests for multicast
765  *      addresses.  If this is one such, delete it.
766  */
767         if (ipv4_is_multicast(tip) ||
768             (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip)))
769                 goto out_free_skb;
770 
771  /*
772   *     For some 802.11 wireless deployments (and possibly other networks),
773   *     there will be an ARP proxy and gratuitous ARP frames are attacks
774   *     and thus should not be accepted.
775   */
776         if (sip == tip && IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP))
777                 goto out_free_skb;
778 
779 /*
780  *     Special case: We must set Frame Relay source Q.922 address
781  */
782         if (dev_type == ARPHRD_DLCI)
783                 sha = dev->broadcast;
784 
785 /*
786  *  Process entry.  The idea here is we want to send a reply if it is a
787  *  request for us or if it is a request for someone else that we hold
788  *  a proxy for.  We want to add an entry to our cache if it is a reply
789  *  to us or if it is a request for our address.
790  *  (The assumption for this last is that if someone is requesting our
791  *  address, they are probably intending to talk to us, so it saves time
792  *  if we cache their address.  Their address is also probably not in
793  *  our cache, since ours is not in their cache.)
794  *
795  *  Putting this another way, we only care about replies if they are to
796  *  us, in which case we add them to the cache.  For requests, we care
797  *  about those for us and those for our proxies.  We reply to both,
798  *  and in the case of requests for us we add the requester to the arp
799  *  cache.
800  */
801 
802         if (arp->ar_op == htons(ARPOP_REQUEST) && skb_metadata_dst(skb))
803                 reply_dst = (struct dst_entry *)
804                             iptunnel_metadata_reply(skb_metadata_dst(skb),
805                                                     GFP_ATOMIC);
806 
807         /* Special case: IPv4 duplicate address detection packet (RFC2131) */
808         if (sip == 0) {
809                 if (arp->ar_op == htons(ARPOP_REQUEST) &&
810                     inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL &&
811                     !arp_ignore(in_dev, sip, tip))
812                         arp_send_dst(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip,
813                                      sha, dev->dev_addr, sha, reply_dst);
814                 goto out_consume_skb;
815         }
816 
817         if (arp->ar_op == htons(ARPOP_REQUEST) &&
818             ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
819 
820                 rt = skb_rtable(skb);
821                 addr_type = rt->rt_type;
822 
823                 if (addr_type == RTN_LOCAL) {
824                         int dont_send;
825 
826                         dont_send = arp_ignore(in_dev, sip, tip);
827                         if (!dont_send && IN_DEV_ARPFILTER(in_dev))
828                                 dont_send = arp_filter(sip, tip, dev);
829                         if (!dont_send) {
830                                 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
831                                 if (n) {
832                                         arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
833                                                      sip, dev, tip, sha,
834                                                      dev->dev_addr, sha,
835                                                      reply_dst);
836                                         neigh_release(n);
837                                 }
838                         }
839                         goto out_consume_skb;
840                 } else if (IN_DEV_FORWARD(in_dev)) {
841                         if (addr_type == RTN_UNICAST  &&
842                             (arp_fwd_proxy(in_dev, dev, rt) ||
843                              arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
844                              (rt->dst.dev != dev &&
845                               pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
846                                 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
847                                 if (n)
848                                         neigh_release(n);
849 
850                                 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
851                                     skb->pkt_type == PACKET_HOST ||
852                                     NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) {
853                                         arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
854                                                      sip, dev, tip, sha,
855                                                      dev->dev_addr, sha,
856                                                      reply_dst);
857                                 } else {
858                                         pneigh_enqueue(&arp_tbl,
859                                                        in_dev->arp_parms, skb);
860                                         goto out_free_dst;
861                                 }
862                                 goto out_consume_skb;
863                         }
864                 }
865         }
866 
867         /* Update our ARP tables */
868 
869         n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
870 
871         addr_type = -1;
872         if (n || IN_DEV_ARP_ACCEPT(in_dev)) {
873                 is_garp = arp_is_garp(net, dev, &addr_type, arp->ar_op,
874                                       sip, tip, sha, tha);
875         }
876 
877         if (IN_DEV_ARP_ACCEPT(in_dev)) {
878                 /* Unsolicited ARP is not accepted by default.
879                    It is possible, that this option should be enabled for some
880                    devices (strip is candidate)
881                  */
882                 if (!n &&
883                     (is_garp ||
884                      (arp->ar_op == htons(ARPOP_REPLY) &&
885                       (addr_type == RTN_UNICAST ||
886                        (addr_type < 0 &&
887                         /* postpone calculation to as late as possible */
888                         inet_addr_type_dev_table(net, dev, sip) ==
889                                 RTN_UNICAST)))))
890                         n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
891         }
892 
893         if (n) {
894                 int state = NUD_REACHABLE;
895                 int override;
896 
897                 /* If several different ARP replies follows back-to-back,
898                    use the FIRST one. It is possible, if several proxy
899                    agents are active. Taking the first reply prevents
900                    arp trashing and chooses the fastest router.
901                  */
902                 override = time_after(jiffies,
903                                       n->updated +
904                                       NEIGH_VAR(n->parms, LOCKTIME)) ||
905                            is_garp;
906 
907                 /* Broadcast replies and request packets
908                    do not assert neighbour reachability.
909                  */
910                 if (arp->ar_op != htons(ARPOP_REPLY) ||
911                     skb->pkt_type != PACKET_HOST)
912                         state = NUD_STALE;
913                 neigh_update(n, sha, state,
914                              override ? NEIGH_UPDATE_F_OVERRIDE : 0, 0);
915                 neigh_release(n);
916         }
917 
918 out_consume_skb:
919         consume_skb(skb);
920 
921 out_free_dst:
922         dst_release(reply_dst);
923         return NET_RX_SUCCESS;
924 
925 out_free_skb:
926         kfree_skb(skb);
927         return NET_RX_DROP;
928 }
929 
930 static void parp_redo(struct sk_buff *skb)
931 {
932         arp_process(dev_net(skb->dev), NULL, skb);
933 }
934 
935 
936 /*
937  *      Receive an arp request from the device layer.
938  */
939 
940 static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
941                    struct packet_type *pt, struct net_device *orig_dev)
942 {
943         const struct arphdr *arp;
944 
945         /* do not tweak dropwatch on an ARP we will ignore */
946         if (dev->flags & IFF_NOARP ||
947             skb->pkt_type == PACKET_OTHERHOST ||
948             skb->pkt_type == PACKET_LOOPBACK)
949                 goto consumeskb;
950 
951         skb = skb_share_check(skb, GFP_ATOMIC);
952         if (!skb)
953                 goto out_of_mem;
954 
955         /* ARP header, plus 2 device addresses, plus 2 IP addresses.  */
956         if (!pskb_may_pull(skb, arp_hdr_len(dev)))
957                 goto freeskb;
958 
959         arp = arp_hdr(skb);
960         if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4)
961                 goto freeskb;
962 
963         memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
964 
965         return NF_HOOK(NFPROTO_ARP, NF_ARP_IN,
966                        dev_net(dev), NULL, skb, dev, NULL,
967                        arp_process);
968 
969 consumeskb:
970         consume_skb(skb);
971         return NET_RX_SUCCESS;
972 freeskb:
973         kfree_skb(skb);
974 out_of_mem:
975         return NET_RX_DROP;
976 }
977 
978 /*
979  *      User level interface (ioctl)
980  */
981 
982 /*
983  *      Set (create) an ARP cache entry.
984  */
985 
986 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
987 {
988         if (!dev) {
989                 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
990                 return 0;
991         }
992         if (__in_dev_get_rtnl(dev)) {
993                 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
994                 return 0;
995         }
996         return -ENXIO;
997 }
998 
999 static int arp_req_set_public(struct net *net, struct arpreq *r,
1000                 struct net_device *dev)
1001 {
1002         __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1003         __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1004 
1005         if (mask && mask != htonl(0xFFFFFFFF))
1006                 return -EINVAL;
1007         if (!dev && (r->arp_flags & ATF_COM)) {
1008                 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family,
1009                                       r->arp_ha.sa_data);
1010                 if (!dev)
1011                         return -ENODEV;
1012         }
1013         if (mask) {
1014                 if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1))
1015                         return -ENOBUFS;
1016                 return 0;
1017         }
1018 
1019         return arp_req_set_proxy(net, dev, 1);
1020 }
1021 
1022 static int arp_req_set(struct net *net, struct arpreq *r,
1023                        struct net_device *dev)
1024 {
1025         __be32 ip;
1026         struct neighbour *neigh;
1027         int err;
1028 
1029         if (r->arp_flags & ATF_PUBL)
1030                 return arp_req_set_public(net, r, dev);
1031 
1032         ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1033         if (r->arp_flags & ATF_PERM)
1034                 r->arp_flags |= ATF_COM;
1035         if (!dev) {
1036                 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1037 
1038                 if (IS_ERR(rt))
1039                         return PTR_ERR(rt);
1040                 dev = rt->dst.dev;
1041                 ip_rt_put(rt);
1042                 if (!dev)
1043                         return -EINVAL;
1044         }
1045         switch (dev->type) {
1046 #if IS_ENABLED(CONFIG_FDDI)
1047         case ARPHRD_FDDI:
1048                 /*
1049                  * According to RFC 1390, FDDI devices should accept ARP
1050                  * hardware types of 1 (Ethernet).  However, to be more
1051                  * robust, we'll accept hardware types of either 1 (Ethernet)
1052                  * or 6 (IEEE 802.2).
1053                  */
1054                 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1055                     r->arp_ha.sa_family != ARPHRD_ETHER &&
1056                     r->arp_ha.sa_family != ARPHRD_IEEE802)
1057                         return -EINVAL;
1058                 break;
1059 #endif
1060         default:
1061                 if (r->arp_ha.sa_family != dev->type)
1062                         return -EINVAL;
1063                 break;
1064         }
1065 
1066         neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1067         err = PTR_ERR(neigh);
1068         if (!IS_ERR(neigh)) {
1069                 unsigned int state = NUD_STALE;
1070                 if (r->arp_flags & ATF_PERM)
1071                         state = NUD_PERMANENT;
1072                 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ?
1073                                    r->arp_ha.sa_data : NULL, state,
1074                                    NEIGH_UPDATE_F_OVERRIDE |
1075                                    NEIGH_UPDATE_F_ADMIN, 0);
1076                 neigh_release(neigh);
1077         }
1078         return err;
1079 }
1080 
1081 static unsigned int arp_state_to_flags(struct neighbour *neigh)
1082 {
1083         if (neigh->nud_state&NUD_PERMANENT)
1084                 return ATF_PERM | ATF_COM;
1085         else if (neigh->nud_state&NUD_VALID)
1086                 return ATF_COM;
1087         else
1088                 return 0;
1089 }
1090 
1091 /*
1092  *      Get an ARP cache entry.
1093  */
1094 
1095 static int arp_req_get(struct arpreq *r, struct net_device *dev)
1096 {
1097         __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1098         struct neighbour *neigh;
1099         int err = -ENXIO;
1100 
1101         neigh = neigh_lookup(&arp_tbl, &ip, dev);
1102         if (neigh) {
1103                 if (!(neigh->nud_state & NUD_NOARP)) {
1104                         read_lock_bh(&neigh->lock);
1105                         memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
1106                         r->arp_flags = arp_state_to_flags(neigh);
1107                         read_unlock_bh(&neigh->lock);
1108                         r->arp_ha.sa_family = dev->type;
1109                         strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1110                         err = 0;
1111                 }
1112                 neigh_release(neigh);
1113         }
1114         return err;
1115 }
1116 
1117 static int arp_invalidate(struct net_device *dev, __be32 ip)
1118 {
1119         struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
1120         int err = -ENXIO;
1121         struct neigh_table *tbl = &arp_tbl;
1122 
1123         if (neigh) {
1124                 if (neigh->nud_state & ~NUD_NOARP)
1125                         err = neigh_update(neigh, NULL, NUD_FAILED,
1126                                            NEIGH_UPDATE_F_OVERRIDE|
1127                                            NEIGH_UPDATE_F_ADMIN, 0);
1128                 write_lock_bh(&tbl->lock);
1129                 neigh_release(neigh);
1130                 neigh_remove_one(neigh, tbl);
1131                 write_unlock_bh(&tbl->lock);
1132         }
1133 
1134         return err;
1135 }
1136 
1137 static int arp_req_delete_public(struct net *net, struct arpreq *r,
1138                 struct net_device *dev)
1139 {
1140         __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1141         __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1142 
1143         if (mask == htonl(0xFFFFFFFF))
1144                 return pneigh_delete(&arp_tbl, net, &ip, dev);
1145 
1146         if (mask)
1147                 return -EINVAL;
1148 
1149         return arp_req_set_proxy(net, dev, 0);
1150 }
1151 
1152 static int arp_req_delete(struct net *net, struct arpreq *r,
1153                           struct net_device *dev)
1154 {
1155         __be32 ip;
1156 
1157         if (r->arp_flags & ATF_PUBL)
1158                 return arp_req_delete_public(net, r, dev);
1159 
1160         ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1161         if (!dev) {
1162                 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1163                 if (IS_ERR(rt))
1164                         return PTR_ERR(rt);
1165                 dev = rt->dst.dev;
1166                 ip_rt_put(rt);
1167                 if (!dev)
1168                         return -EINVAL;
1169         }
1170         return arp_invalidate(dev, ip);
1171 }
1172 
1173 /*
1174  *      Handle an ARP layer I/O control request.
1175  */
1176 
1177 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1178 {
1179         int err;
1180         struct arpreq r;
1181         struct net_device *dev = NULL;
1182 
1183         switch (cmd) {
1184         case SIOCDARP:
1185         case SIOCSARP:
1186                 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1187                         return -EPERM;
1188                 /* fall through */
1189         case SIOCGARP:
1190                 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1191                 if (err)
1192                         return -EFAULT;
1193                 break;
1194         default:
1195                 return -EINVAL;
1196         }
1197 
1198         if (r.arp_pa.sa_family != AF_INET)
1199                 return -EPFNOSUPPORT;
1200 
1201         if (!(r.arp_flags & ATF_PUBL) &&
1202             (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1203                 return -EINVAL;
1204         if (!(r.arp_flags & ATF_NETMASK))
1205                 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1206                                                            htonl(0xFFFFFFFFUL);
1207         rtnl_lock();
1208         if (r.arp_dev[0]) {
1209                 err = -ENODEV;
1210                 dev = __dev_get_by_name(net, r.arp_dev);
1211                 if (!dev)
1212                         goto out;
1213 
1214                 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1215                 if (!r.arp_ha.sa_family)
1216                         r.arp_ha.sa_family = dev->type;
1217                 err = -EINVAL;
1218                 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1219                         goto out;
1220         } else if (cmd == SIOCGARP) {
1221                 err = -ENODEV;
1222                 goto out;
1223         }
1224 
1225         switch (cmd) {
1226         case SIOCDARP:
1227                 err = arp_req_delete(net, &r, dev);
1228                 break;
1229         case SIOCSARP:
1230                 err = arp_req_set(net, &r, dev);
1231                 break;
1232         case SIOCGARP:
1233                 err = arp_req_get(&r, dev);
1234                 break;
1235         }
1236 out:
1237         rtnl_unlock();
1238         if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
1239                 err = -EFAULT;
1240         return err;
1241 }
1242 
1243 static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1244                             void *ptr)
1245 {
1246         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
1247         struct netdev_notifier_change_info *change_info;
1248 
1249         switch (event) {
1250         case NETDEV_CHANGEADDR:
1251                 neigh_changeaddr(&arp_tbl, dev);
1252                 rt_cache_flush(dev_net(dev));
1253                 break;
1254         case NETDEV_CHANGE:
1255                 change_info = ptr;
1256                 if (change_info->flags_changed & IFF_NOARP)
1257                         neigh_changeaddr(&arp_tbl, dev);
1258                 break;
1259         default:
1260                 break;
1261         }
1262 
1263         return NOTIFY_DONE;
1264 }
1265 
1266 static struct notifier_block arp_netdev_notifier = {
1267         .notifier_call = arp_netdev_event,
1268 };
1269 
1270 /* Note, that it is not on notifier chain.
1271    It is necessary, that this routine was called after route cache will be
1272    flushed.
1273  */
1274 void arp_ifdown(struct net_device *dev)
1275 {
1276         neigh_ifdown(&arp_tbl, dev);
1277 }
1278 
1279 
1280 /*
1281  *      Called once on startup.
1282  */
1283 
1284 static struct packet_type arp_packet_type __read_mostly = {
1285         .type = cpu_to_be16(ETH_P_ARP),
1286         .func = arp_rcv,
1287 };
1288 
1289 static int arp_proc_init(void);
1290 
1291 void __init arp_init(void)
1292 {
1293         neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl);
1294 
1295         dev_add_pack(&arp_packet_type);
1296         arp_proc_init();
1297 #ifdef CONFIG_SYSCTL
1298         neigh_sysctl_register(NULL, &arp_tbl.parms, NULL);
1299 #endif
1300         register_netdevice_notifier(&arp_netdev_notifier);
1301 }
1302 
1303 #ifdef CONFIG_PROC_FS
1304 #if IS_ENABLED(CONFIG_AX25)
1305 
1306 /* ------------------------------------------------------------------------ */
1307 /*
1308  *      ax25 -> ASCII conversion
1309  */
1310 static void ax2asc2(ax25_address *a, char *buf)
1311 {
1312         char c, *s;
1313         int n;
1314 
1315         for (n = 0, s = buf; n < 6; n++) {
1316                 c = (a->ax25_call[n] >> 1) & 0x7F;
1317 
1318                 if (c != ' ')
1319                         *s++ = c;
1320         }
1321 
1322         *s++ = '-';
1323         n = (a->ax25_call[6] >> 1) & 0x0F;
1324         if (n > 9) {
1325                 *s++ = '1';
1326                 n -= 10;
1327         }
1328 
1329         *s++ = n + '';
1330         *s++ = '\0';
1331 
1332         if (*buf == '\0' || *buf == '-') {
1333                 buf[0] = '*';
1334                 buf[1] = '\0';
1335         }
1336 }
1337 #endif /* CONFIG_AX25 */
1338 
1339 #define HBUFFERLEN 30
1340 
1341 static void arp_format_neigh_entry(struct seq_file *seq,
1342                                    struct neighbour *n)
1343 {
1344         char hbuffer[HBUFFERLEN];
1345         int k, j;
1346         char tbuf[16];
1347         struct net_device *dev = n->dev;
1348         int hatype = dev->type;
1349 
1350         read_lock(&n->lock);
1351         /* Convert hardware address to XX:XX:XX:XX ... form. */
1352 #if IS_ENABLED(CONFIG_AX25)
1353         if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
1354                 ax2asc2((ax25_address *)n->ha, hbuffer);
1355         else {
1356 #endif
1357         for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
1358                 hbuffer[k++] = hex_asc_hi(n->ha[j]);
1359                 hbuffer[k++] = hex_asc_lo(n->ha[j]);
1360                 hbuffer[k++] = ':';
1361         }
1362         if (k != 0)
1363                 --k;
1364         hbuffer[k] = 0;
1365 #if IS_ENABLED(CONFIG_AX25)
1366         }
1367 #endif
1368         sprintf(tbuf, "%pI4", n->primary_key);
1369         seq_printf(seq, "%-16s 0x%-10x0x%-10x%-17s     *        %s\n",
1370                    tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
1371         read_unlock(&n->lock);
1372 }
1373 
1374 static void arp_format_pneigh_entry(struct seq_file *seq,
1375                                     struct pneigh_entry *n)
1376 {
1377         struct net_device *dev = n->dev;
1378         int hatype = dev ? dev->type : 0;
1379         char tbuf[16];
1380 
1381         sprintf(tbuf, "%pI4", n->key);
1382         seq_printf(seq, "%-16s 0x%-10x0x%-10x%s     *        %s\n",
1383                    tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
1384                    dev ? dev->name : "*");
1385 }
1386 
1387 static int arp_seq_show(struct seq_file *seq, void *v)
1388 {
1389         if (v == SEQ_START_TOKEN) {
1390                 seq_puts(seq, "IP address       HW type     Flags       "
1391                               "HW address            Mask     Device\n");
1392         } else {
1393                 struct neigh_seq_state *state = seq->private;
1394 
1395                 if (state->flags & NEIGH_SEQ_IS_PNEIGH)
1396                         arp_format_pneigh_entry(seq, v);
1397                 else
1398                         arp_format_neigh_entry(seq, v);
1399         }
1400 
1401         return 0;
1402 }
1403 
1404 static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
1405 {
1406         /* Don't want to confuse "arp -a" w/ magic entries,
1407          * so we tell the generic iterator to skip NUD_NOARP.
1408          */
1409         return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
1410 }
1411 
1412 /* ------------------------------------------------------------------------ */
1413 
1414 static const struct seq_operations arp_seq_ops = {
1415         .start  = arp_seq_start,
1416         .next   = neigh_seq_next,
1417         .stop   = neigh_seq_stop,
1418         .show   = arp_seq_show,
1419 };
1420 
1421 /* ------------------------------------------------------------------------ */
1422 
1423 static int __net_init arp_net_init(struct net *net)
1424 {
1425         if (!proc_create_net("arp", 0444, net->proc_net, &arp_seq_ops,
1426                         sizeof(struct neigh_seq_state)))
1427                 return -ENOMEM;
1428         return 0;
1429 }
1430 
1431 static void __net_exit arp_net_exit(struct net *net)
1432 {
1433         remove_proc_entry("arp", net->proc_net);
1434 }
1435 
1436 static struct pernet_operations arp_net_ops = {
1437         .init = arp_net_init,
1438         .exit = arp_net_exit,
1439 };
1440 
1441 static int __init arp_proc_init(void)
1442 {
1443         return register_pernet_subsys(&arp_net_ops);
1444 }
1445 
1446 #else /* CONFIG_PROC_FS */
1447 
1448 static int __init arp_proc_init(void)
1449 {
1450         return 0;
1451 }
1452 
1453 #endif /* CONFIG_PROC_FS */
1454 

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