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Linux/net/ipv4/arp.c

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /* linux/net/ipv4/arp.c
  3  *
  4  * Copyright (C) 1994 by Florian  La Roche
  5  *
  6  * This module implements the Address Resolution Protocol ARP (RFC 826),
  7  * which is used to convert IP addresses (or in the future maybe other
  8  * high-level addresses) into a low-level hardware address (like an Ethernet
  9  * address).
 10  *
 11  * Fixes:
 12  *              Alan Cox        :       Removed the Ethernet assumptions in
 13  *                                      Florian's code
 14  *              Alan Cox        :       Fixed some small errors in the ARP
 15  *                                      logic
 16  *              Alan Cox        :       Allow >4K in /proc
 17  *              Alan Cox        :       Make ARP add its own protocol entry
 18  *              Ross Martin     :       Rewrote arp_rcv() and arp_get_info()
 19  *              Stephen Henson  :       Add AX25 support to arp_get_info()
 20  *              Alan Cox        :       Drop data when a device is downed.
 21  *              Alan Cox        :       Use init_timer().
 22  *              Alan Cox        :       Double lock fixes.
 23  *              Martin Seine    :       Move the arphdr structure
 24  *                                      to if_arp.h for compatibility.
 25  *                                      with BSD based programs.
 26  *              Andrew Tridgell :       Added ARP netmask code and
 27  *                                      re-arranged proxy handling.
 28  *              Alan Cox        :       Changed to use notifiers.
 29  *              Niibe Yutaka    :       Reply for this device or proxies only.
 30  *              Alan Cox        :       Don't proxy across hardware types!
 31  *              Jonathan Naylor :       Added support for NET/ROM.
 32  *              Mike Shaver     :       RFC1122 checks.
 33  *              Jonathan Naylor :       Only lookup the hardware address for
 34  *                                      the correct hardware type.
 35  *              Germano Caronni :       Assorted subtle races.
 36  *              Craig Schlenter :       Don't modify permanent entry
 37  *                                      during arp_rcv.
 38  *              Russ Nelson     :       Tidied up a few bits.
 39  *              Alexey Kuznetsov:       Major changes to caching and behaviour,
 40  *                                      eg intelligent arp probing and
 41  *                                      generation
 42  *                                      of host down events.
 43  *              Alan Cox        :       Missing unlock in device events.
 44  *              Eckes           :       ARP ioctl control errors.
 45  *              Alexey Kuznetsov:       Arp free fix.
 46  *              Manuel Rodriguez:       Gratuitous ARP.
 47  *              Jonathan Layes  :       Added arpd support through kerneld
 48  *                                      message queue (960314)
 49  *              Mike Shaver     :       /proc/sys/net/ipv4/arp_* support
 50  *              Mike McLagan    :       Routing by source
 51  *              Stuart Cheshire :       Metricom and grat arp fixes
 52  *                                      *** FOR 2.1 clean this up ***
 53  *              Lawrence V. Stefani: (08/12/96) Added FDDI support.
 54  *              Alan Cox        :       Took the AP1000 nasty FDDI hack and
 55  *                                      folded into the mainstream FDDI code.
 56  *                                      Ack spit, Linus how did you allow that
 57  *                                      one in...
 58  *              Jes Sorensen    :       Make FDDI work again in 2.1.x and
 59  *                                      clean up the APFDDI & gen. FDDI bits.
 60  *              Alexey Kuznetsov:       new arp state machine;
 61  *                                      now it is in net/core/neighbour.c.
 62  *              Krzysztof Halasa:       Added Frame Relay ARP support.
 63  *              Arnaldo C. Melo :       convert /proc/net/arp to seq_file
 64  *              Shmulik Hen:            Split arp_send to arp_create and
 65  *                                      arp_xmit so intermediate drivers like
 66  *                                      bonding can change the skb before
 67  *                                      sending (e.g. insert 8021q tag).
 68  *              Harald Welte    :       convert to make use of jenkins hash
 69  *              Jesper D. Brouer:       Proxy ARP PVLAN RFC 3069 support.
 70  */
 71 
 72 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 73 
 74 #include <linux/module.h>
 75 #include <linux/types.h>
 76 #include <linux/string.h>
 77 #include <linux/kernel.h>
 78 #include <linux/capability.h>
 79 #include <linux/socket.h>
 80 #include <linux/sockios.h>
 81 #include <linux/errno.h>
 82 #include <linux/in.h>
 83 #include <linux/mm.h>
 84 #include <linux/inet.h>
 85 #include <linux/inetdevice.h>
 86 #include <linux/netdevice.h>
 87 #include <linux/etherdevice.h>
 88 #include <linux/fddidevice.h>
 89 #include <linux/if_arp.h>
 90 #include <linux/skbuff.h>
 91 #include <linux/proc_fs.h>
 92 #include <linux/seq_file.h>
 93 #include <linux/stat.h>
 94 #include <linux/init.h>
 95 #include <linux/net.h>
 96 #include <linux/rcupdate.h>
 97 #include <linux/slab.h>
 98 #ifdef CONFIG_SYSCTL
 99 #include <linux/sysctl.h>
100 #endif
101 
102 #include <net/net_namespace.h>
103 #include <net/ip.h>
104 #include <net/icmp.h>
105 #include <net/route.h>
106 #include <net/protocol.h>
107 #include <net/tcp.h>
108 #include <net/sock.h>
109 #include <net/arp.h>
110 #include <net/ax25.h>
111 #include <net/netrom.h>
112 #include <net/dst_metadata.h>
113 #include <net/ip_tunnels.h>
114 
115 #include <linux/uaccess.h>
116 
117 #include <linux/netfilter_arp.h>
118 
119 /*
120  *      Interface to generic neighbour cache.
121  */
122 static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd);
123 static bool arp_key_eq(const struct neighbour *n, const void *pkey);
124 static int arp_constructor(struct neighbour *neigh);
125 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
126 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
127 static void parp_redo(struct sk_buff *skb);
128 
129 static const struct neigh_ops arp_generic_ops = {
130         .family =               AF_INET,
131         .solicit =              arp_solicit,
132         .error_report =         arp_error_report,
133         .output =               neigh_resolve_output,
134         .connected_output =     neigh_connected_output,
135 };
136 
137 static const struct neigh_ops arp_hh_ops = {
138         .family =               AF_INET,
139         .solicit =              arp_solicit,
140         .error_report =         arp_error_report,
141         .output =               neigh_resolve_output,
142         .connected_output =     neigh_resolve_output,
143 };
144 
145 static const struct neigh_ops arp_direct_ops = {
146         .family =               AF_INET,
147         .output =               neigh_direct_output,
148         .connected_output =     neigh_direct_output,
149 };
150 
151 struct neigh_table arp_tbl = {
152         .family         = AF_INET,
153         .key_len        = 4,
154         .protocol       = cpu_to_be16(ETH_P_IP),
155         .hash           = arp_hash,
156         .key_eq         = arp_key_eq,
157         .constructor    = arp_constructor,
158         .proxy_redo     = parp_redo,
159         .id             = "arp_cache",
160         .parms          = {
161                 .tbl                    = &arp_tbl,
162                 .reachable_time         = 30 * HZ,
163                 .data   = {
164                         [NEIGH_VAR_MCAST_PROBES] = 3,
165                         [NEIGH_VAR_UCAST_PROBES] = 3,
166                         [NEIGH_VAR_RETRANS_TIME] = 1 * HZ,
167                         [NEIGH_VAR_BASE_REACHABLE_TIME] = 30 * HZ,
168                         [NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ,
169                         [NEIGH_VAR_GC_STALETIME] = 60 * HZ,
170                         [NEIGH_VAR_QUEUE_LEN_BYTES] = SK_WMEM_MAX,
171                         [NEIGH_VAR_PROXY_QLEN] = 64,
172                         [NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ,
173                         [NEIGH_VAR_PROXY_DELAY] = (8 * HZ) / 10,
174                         [NEIGH_VAR_LOCKTIME] = 1 * HZ,
175                 },
176         },
177         .gc_interval    = 30 * HZ,
178         .gc_thresh1     = 128,
179         .gc_thresh2     = 512,
180         .gc_thresh3     = 1024,
181 };
182 EXPORT_SYMBOL(arp_tbl);
183 
184 int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir)
185 {
186         switch (dev->type) {
187         case ARPHRD_ETHER:
188         case ARPHRD_FDDI:
189         case ARPHRD_IEEE802:
190                 ip_eth_mc_map(addr, haddr);
191                 return 0;
192         case ARPHRD_INFINIBAND:
193                 ip_ib_mc_map(addr, dev->broadcast, haddr);
194                 return 0;
195         case ARPHRD_IPGRE:
196                 ip_ipgre_mc_map(addr, dev->broadcast, haddr);
197                 return 0;
198         default:
199                 if (dir) {
200                         memcpy(haddr, dev->broadcast, dev->addr_len);
201                         return 0;
202                 }
203         }
204         return -EINVAL;
205 }
206 
207 
208 static u32 arp_hash(const void *pkey,
209                     const struct net_device *dev,
210                     __u32 *hash_rnd)
211 {
212         return arp_hashfn(pkey, dev, hash_rnd);
213 }
214 
215 static bool arp_key_eq(const struct neighbour *neigh, const void *pkey)
216 {
217         return neigh_key_eq32(neigh, pkey);
218 }
219 
220 static int arp_constructor(struct neighbour *neigh)
221 {
222         __be32 addr;
223         struct net_device *dev = neigh->dev;
224         struct in_device *in_dev;
225         struct neigh_parms *parms;
226         u32 inaddr_any = INADDR_ANY;
227 
228         if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT))
229                 memcpy(neigh->primary_key, &inaddr_any, arp_tbl.key_len);
230 
231         addr = *(__be32 *)neigh->primary_key;
232         rcu_read_lock();
233         in_dev = __in_dev_get_rcu(dev);
234         if (!in_dev) {
235                 rcu_read_unlock();
236                 return -EINVAL;
237         }
238 
239         neigh->type = inet_addr_type_dev_table(dev_net(dev), dev, addr);
240 
241         parms = in_dev->arp_parms;
242         __neigh_parms_put(neigh->parms);
243         neigh->parms = neigh_parms_clone(parms);
244         rcu_read_unlock();
245 
246         if (!dev->header_ops) {
247                 neigh->nud_state = NUD_NOARP;
248                 neigh->ops = &arp_direct_ops;
249                 neigh->output = neigh_direct_output;
250         } else {
251                 /* Good devices (checked by reading texts, but only Ethernet is
252                    tested)
253 
254                    ARPHRD_ETHER: (ethernet, apfddi)
255                    ARPHRD_FDDI: (fddi)
256                    ARPHRD_IEEE802: (tr)
257                    ARPHRD_METRICOM: (strip)
258                    ARPHRD_ARCNET:
259                    etc. etc. etc.
260 
261                    ARPHRD_IPDDP will also work, if author repairs it.
262                    I did not it, because this driver does not work even
263                    in old paradigm.
264                  */
265 
266                 if (neigh->type == RTN_MULTICAST) {
267                         neigh->nud_state = NUD_NOARP;
268                         arp_mc_map(addr, neigh->ha, dev, 1);
269                 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) {
270                         neigh->nud_state = NUD_NOARP;
271                         memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
272                 } else if (neigh->type == RTN_BROADCAST ||
273                            (dev->flags & IFF_POINTOPOINT)) {
274                         neigh->nud_state = NUD_NOARP;
275                         memcpy(neigh->ha, dev->broadcast, dev->addr_len);
276                 }
277 
278                 if (dev->header_ops->cache)
279                         neigh->ops = &arp_hh_ops;
280                 else
281                         neigh->ops = &arp_generic_ops;
282 
283                 if (neigh->nud_state & NUD_VALID)
284                         neigh->output = neigh->ops->connected_output;
285                 else
286                         neigh->output = neigh->ops->output;
287         }
288         return 0;
289 }
290 
291 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
292 {
293         dst_link_failure(skb);
294         kfree_skb(skb);
295 }
296 
297 /* Create and send an arp packet. */
298 static void arp_send_dst(int type, int ptype, __be32 dest_ip,
299                          struct net_device *dev, __be32 src_ip,
300                          const unsigned char *dest_hw,
301                          const unsigned char *src_hw,
302                          const unsigned char *target_hw,
303                          struct dst_entry *dst)
304 {
305         struct sk_buff *skb;
306 
307         /* arp on this interface. */
308         if (dev->flags & IFF_NOARP)
309                 return;
310 
311         skb = arp_create(type, ptype, dest_ip, dev, src_ip,
312                          dest_hw, src_hw, target_hw);
313         if (!skb)
314                 return;
315 
316         skb_dst_set(skb, dst_clone(dst));
317         arp_xmit(skb);
318 }
319 
320 void arp_send(int type, int ptype, __be32 dest_ip,
321               struct net_device *dev, __be32 src_ip,
322               const unsigned char *dest_hw, const unsigned char *src_hw,
323               const unsigned char *target_hw)
324 {
325         arp_send_dst(type, ptype, dest_ip, dev, src_ip, dest_hw, src_hw,
326                      target_hw, NULL);
327 }
328 EXPORT_SYMBOL(arp_send);
329 
330 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
331 {
332         __be32 saddr = 0;
333         u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL;
334         struct net_device *dev = neigh->dev;
335         __be32 target = *(__be32 *)neigh->primary_key;
336         int probes = atomic_read(&neigh->probes);
337         struct in_device *in_dev;
338         struct dst_entry *dst = NULL;
339 
340         rcu_read_lock();
341         in_dev = __in_dev_get_rcu(dev);
342         if (!in_dev) {
343                 rcu_read_unlock();
344                 return;
345         }
346         switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
347         default:
348         case 0:         /* By default announce any local IP */
349                 if (skb && inet_addr_type_dev_table(dev_net(dev), dev,
350                                           ip_hdr(skb)->saddr) == RTN_LOCAL)
351                         saddr = ip_hdr(skb)->saddr;
352                 break;
353         case 1:         /* Restrict announcements of saddr in same subnet */
354                 if (!skb)
355                         break;
356                 saddr = ip_hdr(skb)->saddr;
357                 if (inet_addr_type_dev_table(dev_net(dev), dev,
358                                              saddr) == RTN_LOCAL) {
359                         /* saddr should be known to target */
360                         if (inet_addr_onlink(in_dev, target, saddr))
361                                 break;
362                 }
363                 saddr = 0;
364                 break;
365         case 2:         /* Avoid secondary IPs, get a primary/preferred one */
366                 break;
367         }
368         rcu_read_unlock();
369 
370         if (!saddr)
371                 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
372 
373         probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES);
374         if (probes < 0) {
375                 if (!(neigh->nud_state & NUD_VALID))
376                         pr_debug("trying to ucast probe in NUD_INVALID\n");
377                 neigh_ha_snapshot(dst_ha, neigh, dev);
378                 dst_hw = dst_ha;
379         } else {
380                 probes -= NEIGH_VAR(neigh->parms, APP_PROBES);
381                 if (probes < 0) {
382                         neigh_app_ns(neigh);
383                         return;
384                 }
385         }
386 
387         if (skb && !(dev->priv_flags & IFF_XMIT_DST_RELEASE))
388                 dst = skb_dst(skb);
389         arp_send_dst(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
390                      dst_hw, dev->dev_addr, NULL, dst);
391 }
392 
393 static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip)
394 {
395         struct net *net = dev_net(in_dev->dev);
396         int scope;
397 
398         switch (IN_DEV_ARP_IGNORE(in_dev)) {
399         case 0: /* Reply, the tip is already validated */
400                 return 0;
401         case 1: /* Reply only if tip is configured on the incoming interface */
402                 sip = 0;
403                 scope = RT_SCOPE_HOST;
404                 break;
405         case 2: /*
406                  * Reply only if tip is configured on the incoming interface
407                  * and is in same subnet as sip
408                  */
409                 scope = RT_SCOPE_HOST;
410                 break;
411         case 3: /* Do not reply for scope host addresses */
412                 sip = 0;
413                 scope = RT_SCOPE_LINK;
414                 in_dev = NULL;
415                 break;
416         case 4: /* Reserved */
417         case 5:
418         case 6:
419         case 7:
420                 return 0;
421         case 8: /* Do not reply */
422                 return 1;
423         default:
424                 return 0;
425         }
426         return !inet_confirm_addr(net, in_dev, sip, tip, scope);
427 }
428 
429 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
430 {
431         struct rtable *rt;
432         int flag = 0;
433         /*unsigned long now; */
434         struct net *net = dev_net(dev);
435 
436         rt = ip_route_output(net, sip, tip, 0, l3mdev_master_ifindex_rcu(dev));
437         if (IS_ERR(rt))
438                 return 1;
439         if (rt->dst.dev != dev) {
440                 __NET_INC_STATS(net, LINUX_MIB_ARPFILTER);
441                 flag = 1;
442         }
443         ip_rt_put(rt);
444         return flag;
445 }
446 
447 /*
448  * Check if we can use proxy ARP for this path
449  */
450 static inline int arp_fwd_proxy(struct in_device *in_dev,
451                                 struct net_device *dev, struct rtable *rt)
452 {
453         struct in_device *out_dev;
454         int imi, omi = -1;
455 
456         if (rt->dst.dev == dev)
457                 return 0;
458 
459         if (!IN_DEV_PROXY_ARP(in_dev))
460                 return 0;
461         imi = IN_DEV_MEDIUM_ID(in_dev);
462         if (imi == 0)
463                 return 1;
464         if (imi == -1)
465                 return 0;
466 
467         /* place to check for proxy_arp for routes */
468 
469         out_dev = __in_dev_get_rcu(rt->dst.dev);
470         if (out_dev)
471                 omi = IN_DEV_MEDIUM_ID(out_dev);
472 
473         return omi != imi && omi != -1;
474 }
475 
476 /*
477  * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
478  *
479  * RFC3069 supports proxy arp replies back to the same interface.  This
480  * is done to support (ethernet) switch features, like RFC 3069, where
481  * the individual ports are not allowed to communicate with each
482  * other, BUT they are allowed to talk to the upstream router.  As
483  * described in RFC 3069, it is possible to allow these hosts to
484  * communicate through the upstream router, by proxy_arp'ing.
485  *
486  * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
487  *
488  *  This technology is known by different names:
489  *    In RFC 3069 it is called VLAN Aggregation.
490  *    Cisco and Allied Telesyn call it Private VLAN.
491  *    Hewlett-Packard call it Source-Port filtering or port-isolation.
492  *    Ericsson call it MAC-Forced Forwarding (RFC Draft).
493  *
494  */
495 static inline int arp_fwd_pvlan(struct in_device *in_dev,
496                                 struct net_device *dev, struct rtable *rt,
497                                 __be32 sip, __be32 tip)
498 {
499         /* Private VLAN is only concerned about the same ethernet segment */
500         if (rt->dst.dev != dev)
501                 return 0;
502 
503         /* Don't reply on self probes (often done by windowz boxes)*/
504         if (sip == tip)
505                 return 0;
506 
507         if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
508                 return 1;
509         else
510                 return 0;
511 }
512 
513 /*
514  *      Interface to link layer: send routine and receive handler.
515  */
516 
517 /*
518  *      Create an arp packet. If dest_hw is not set, we create a broadcast
519  *      message.
520  */
521 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
522                            struct net_device *dev, __be32 src_ip,
523                            const unsigned char *dest_hw,
524                            const unsigned char *src_hw,
525                            const unsigned char *target_hw)
526 {
527         struct sk_buff *skb;
528         struct arphdr *arp;
529         unsigned char *arp_ptr;
530         int hlen = LL_RESERVED_SPACE(dev);
531         int tlen = dev->needed_tailroom;
532 
533         /*
534          *      Allocate a buffer
535          */
536 
537         skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
538         if (!skb)
539                 return NULL;
540 
541         skb_reserve(skb, hlen);
542         skb_reset_network_header(skb);
543         arp = skb_put(skb, arp_hdr_len(dev));
544         skb->dev = dev;
545         skb->protocol = htons(ETH_P_ARP);
546         if (!src_hw)
547                 src_hw = dev->dev_addr;
548         if (!dest_hw)
549                 dest_hw = dev->broadcast;
550 
551         /*
552          *      Fill the device header for the ARP frame
553          */
554         if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
555                 goto out;
556 
557         /*
558          * Fill out the arp protocol part.
559          *
560          * The arp hardware type should match the device type, except for FDDI,
561          * which (according to RFC 1390) should always equal 1 (Ethernet).
562          */
563         /*
564          *      Exceptions everywhere. AX.25 uses the AX.25 PID value not the
565          *      DIX code for the protocol. Make these device structure fields.
566          */
567         switch (dev->type) {
568         default:
569                 arp->ar_hrd = htons(dev->type);
570                 arp->ar_pro = htons(ETH_P_IP);
571                 break;
572 
573 #if IS_ENABLED(CONFIG_AX25)
574         case ARPHRD_AX25:
575                 arp->ar_hrd = htons(ARPHRD_AX25);
576                 arp->ar_pro = htons(AX25_P_IP);
577                 break;
578 
579 #if IS_ENABLED(CONFIG_NETROM)
580         case ARPHRD_NETROM:
581                 arp->ar_hrd = htons(ARPHRD_NETROM);
582                 arp->ar_pro = htons(AX25_P_IP);
583                 break;
584 #endif
585 #endif
586 
587 #if IS_ENABLED(CONFIG_FDDI)
588         case ARPHRD_FDDI:
589                 arp->ar_hrd = htons(ARPHRD_ETHER);
590                 arp->ar_pro = htons(ETH_P_IP);
591                 break;
592 #endif
593         }
594 
595         arp->ar_hln = dev->addr_len;
596         arp->ar_pln = 4;
597         arp->ar_op = htons(type);
598 
599         arp_ptr = (unsigned char *)(arp + 1);
600 
601         memcpy(arp_ptr, src_hw, dev->addr_len);
602         arp_ptr += dev->addr_len;
603         memcpy(arp_ptr, &src_ip, 4);
604         arp_ptr += 4;
605 
606         switch (dev->type) {
607 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
608         case ARPHRD_IEEE1394:
609                 break;
610 #endif
611         default:
612                 if (target_hw)
613                         memcpy(arp_ptr, target_hw, dev->addr_len);
614                 else
615                         memset(arp_ptr, 0, dev->addr_len);
616                 arp_ptr += dev->addr_len;
617         }
618         memcpy(arp_ptr, &dest_ip, 4);
619 
620         return skb;
621 
622 out:
623         kfree_skb(skb);
624         return NULL;
625 }
626 EXPORT_SYMBOL(arp_create);
627 
628 static int arp_xmit_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
629 {
630         return dev_queue_xmit(skb);
631 }
632 
633 /*
634  *      Send an arp packet.
635  */
636 void arp_xmit(struct sk_buff *skb)
637 {
638         /* Send it off, maybe filter it using firewalling first.  */
639         NF_HOOK(NFPROTO_ARP, NF_ARP_OUT,
640                 dev_net(skb->dev), NULL, skb, NULL, skb->dev,
641                 arp_xmit_finish);
642 }
643 EXPORT_SYMBOL(arp_xmit);
644 
645 static bool arp_is_garp(struct net *net, struct net_device *dev,
646                         int *addr_type, __be16 ar_op,
647                         __be32 sip, __be32 tip,
648                         unsigned char *sha, unsigned char *tha)
649 {
650         bool is_garp = tip == sip;
651 
652         /* Gratuitous ARP _replies_ also require target hwaddr to be
653          * the same as source.
654          */
655         if (is_garp && ar_op == htons(ARPOP_REPLY))
656                 is_garp =
657                         /* IPv4 over IEEE 1394 doesn't provide target
658                          * hardware address field in its ARP payload.
659                          */
660                         tha &&
661                         !memcmp(tha, sha, dev->addr_len);
662 
663         if (is_garp) {
664                 *addr_type = inet_addr_type_dev_table(net, dev, sip);
665                 if (*addr_type != RTN_UNICAST)
666                         is_garp = false;
667         }
668         return is_garp;
669 }
670 
671 /*
672  *      Process an arp request.
673  */
674 
675 static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb)
676 {
677         struct net_device *dev = skb->dev;
678         struct in_device *in_dev = __in_dev_get_rcu(dev);
679         struct arphdr *arp;
680         unsigned char *arp_ptr;
681         struct rtable *rt;
682         unsigned char *sha;
683         unsigned char *tha = NULL;
684         __be32 sip, tip;
685         u16 dev_type = dev->type;
686         int addr_type;
687         struct neighbour *n;
688         struct dst_entry *reply_dst = NULL;
689         bool is_garp = false;
690 
691         /* arp_rcv below verifies the ARP header and verifies the device
692          * is ARP'able.
693          */
694 
695         if (!in_dev)
696                 goto out_free_skb;
697 
698         arp = arp_hdr(skb);
699 
700         switch (dev_type) {
701         default:
702                 if (arp->ar_pro != htons(ETH_P_IP) ||
703                     htons(dev_type) != arp->ar_hrd)
704                         goto out_free_skb;
705                 break;
706         case ARPHRD_ETHER:
707         case ARPHRD_FDDI:
708         case ARPHRD_IEEE802:
709                 /*
710                  * ETHERNET, and Fibre Channel (which are IEEE 802
711                  * devices, according to RFC 2625) devices will accept ARP
712                  * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
713                  * This is the case also of FDDI, where the RFC 1390 says that
714                  * FDDI devices should accept ARP hardware of (1) Ethernet,
715                  * however, to be more robust, we'll accept both 1 (Ethernet)
716                  * or 6 (IEEE 802.2)
717                  */
718                 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
719                      arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
720                     arp->ar_pro != htons(ETH_P_IP))
721                         goto out_free_skb;
722                 break;
723         case ARPHRD_AX25:
724                 if (arp->ar_pro != htons(AX25_P_IP) ||
725                     arp->ar_hrd != htons(ARPHRD_AX25))
726                         goto out_free_skb;
727                 break;
728         case ARPHRD_NETROM:
729                 if (arp->ar_pro != htons(AX25_P_IP) ||
730                     arp->ar_hrd != htons(ARPHRD_NETROM))
731                         goto out_free_skb;
732                 break;
733         }
734 
735         /* Understand only these message types */
736 
737         if (arp->ar_op != htons(ARPOP_REPLY) &&
738             arp->ar_op != htons(ARPOP_REQUEST))
739                 goto out_free_skb;
740 
741 /*
742  *      Extract fields
743  */
744         arp_ptr = (unsigned char *)(arp + 1);
745         sha     = arp_ptr;
746         arp_ptr += dev->addr_len;
747         memcpy(&sip, arp_ptr, 4);
748         arp_ptr += 4;
749         switch (dev_type) {
750 #if IS_ENABLED(CONFIG_FIREWIRE_NET)
751         case ARPHRD_IEEE1394:
752                 break;
753 #endif
754         default:
755                 tha = arp_ptr;
756                 arp_ptr += dev->addr_len;
757         }
758         memcpy(&tip, arp_ptr, 4);
759 /*
760  *      Check for bad requests for 127.x.x.x and requests for multicast
761  *      addresses.  If this is one such, delete it.
762  */
763         if (ipv4_is_multicast(tip) ||
764             (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip)))
765                 goto out_free_skb;
766 
767  /*
768   *     For some 802.11 wireless deployments (and possibly other networks),
769   *     there will be an ARP proxy and gratuitous ARP frames are attacks
770   *     and thus should not be accepted.
771   */
772         if (sip == tip && IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP))
773                 goto out_free_skb;
774 
775 /*
776  *     Special case: We must set Frame Relay source Q.922 address
777  */
778         if (dev_type == ARPHRD_DLCI)
779                 sha = dev->broadcast;
780 
781 /*
782  *  Process entry.  The idea here is we want to send a reply if it is a
783  *  request for us or if it is a request for someone else that we hold
784  *  a proxy for.  We want to add an entry to our cache if it is a reply
785  *  to us or if it is a request for our address.
786  *  (The assumption for this last is that if someone is requesting our
787  *  address, they are probably intending to talk to us, so it saves time
788  *  if we cache their address.  Their address is also probably not in
789  *  our cache, since ours is not in their cache.)
790  *
791  *  Putting this another way, we only care about replies if they are to
792  *  us, in which case we add them to the cache.  For requests, we care
793  *  about those for us and those for our proxies.  We reply to both,
794  *  and in the case of requests for us we add the requester to the arp
795  *  cache.
796  */
797 
798         if (arp->ar_op == htons(ARPOP_REQUEST) && skb_metadata_dst(skb))
799                 reply_dst = (struct dst_entry *)
800                             iptunnel_metadata_reply(skb_metadata_dst(skb),
801                                                     GFP_ATOMIC);
802 
803         /* Special case: IPv4 duplicate address detection packet (RFC2131) */
804         if (sip == 0) {
805                 if (arp->ar_op == htons(ARPOP_REQUEST) &&
806                     inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL &&
807                     !arp_ignore(in_dev, sip, tip))
808                         arp_send_dst(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip,
809                                      sha, dev->dev_addr, sha, reply_dst);
810                 goto out_consume_skb;
811         }
812 
813         if (arp->ar_op == htons(ARPOP_REQUEST) &&
814             ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
815 
816                 rt = skb_rtable(skb);
817                 addr_type = rt->rt_type;
818 
819                 if (addr_type == RTN_LOCAL) {
820                         int dont_send;
821 
822                         dont_send = arp_ignore(in_dev, sip, tip);
823                         if (!dont_send && IN_DEV_ARPFILTER(in_dev))
824                                 dont_send = arp_filter(sip, tip, dev);
825                         if (!dont_send) {
826                                 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
827                                 if (n) {
828                                         arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
829                                                      sip, dev, tip, sha,
830                                                      dev->dev_addr, sha,
831                                                      reply_dst);
832                                         neigh_release(n);
833                                 }
834                         }
835                         goto out_consume_skb;
836                 } else if (IN_DEV_FORWARD(in_dev)) {
837                         if (addr_type == RTN_UNICAST  &&
838                             (arp_fwd_proxy(in_dev, dev, rt) ||
839                              arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
840                              (rt->dst.dev != dev &&
841                               pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
842                                 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
843                                 if (n)
844                                         neigh_release(n);
845 
846                                 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
847                                     skb->pkt_type == PACKET_HOST ||
848                                     NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) {
849                                         arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
850                                                      sip, dev, tip, sha,
851                                                      dev->dev_addr, sha,
852                                                      reply_dst);
853                                 } else {
854                                         pneigh_enqueue(&arp_tbl,
855                                                        in_dev->arp_parms, skb);
856                                         goto out_free_dst;
857                                 }
858                                 goto out_consume_skb;
859                         }
860                 }
861         }
862 
863         /* Update our ARP tables */
864 
865         n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
866 
867         addr_type = -1;
868         if (n || IN_DEV_ARP_ACCEPT(in_dev)) {
869                 is_garp = arp_is_garp(net, dev, &addr_type, arp->ar_op,
870                                       sip, tip, sha, tha);
871         }
872 
873         if (IN_DEV_ARP_ACCEPT(in_dev)) {
874                 /* Unsolicited ARP is not accepted by default.
875                    It is possible, that this option should be enabled for some
876                    devices (strip is candidate)
877                  */
878                 if (!n &&
879                     (is_garp ||
880                      (arp->ar_op == htons(ARPOP_REPLY) &&
881                       (addr_type == RTN_UNICAST ||
882                        (addr_type < 0 &&
883                         /* postpone calculation to as late as possible */
884                         inet_addr_type_dev_table(net, dev, sip) ==
885                                 RTN_UNICAST)))))
886                         n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
887         }
888 
889         if (n) {
890                 int state = NUD_REACHABLE;
891                 int override;
892 
893                 /* If several different ARP replies follows back-to-back,
894                    use the FIRST one. It is possible, if several proxy
895                    agents are active. Taking the first reply prevents
896                    arp trashing and chooses the fastest router.
897                  */
898                 override = time_after(jiffies,
899                                       n->updated +
900                                       NEIGH_VAR(n->parms, LOCKTIME)) ||
901                            is_garp;
902 
903                 /* Broadcast replies and request packets
904                    do not assert neighbour reachability.
905                  */
906                 if (arp->ar_op != htons(ARPOP_REPLY) ||
907                     skb->pkt_type != PACKET_HOST)
908                         state = NUD_STALE;
909                 neigh_update(n, sha, state,
910                              override ? NEIGH_UPDATE_F_OVERRIDE : 0, 0);
911                 neigh_release(n);
912         }
913 
914 out_consume_skb:
915         consume_skb(skb);
916 
917 out_free_dst:
918         dst_release(reply_dst);
919         return NET_RX_SUCCESS;
920 
921 out_free_skb:
922         kfree_skb(skb);
923         return NET_RX_DROP;
924 }
925 
926 static void parp_redo(struct sk_buff *skb)
927 {
928         arp_process(dev_net(skb->dev), NULL, skb);
929 }
930 
931 
932 /*
933  *      Receive an arp request from the device layer.
934  */
935 
936 static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
937                    struct packet_type *pt, struct net_device *orig_dev)
938 {
939         const struct arphdr *arp;
940 
941         /* do not tweak dropwatch on an ARP we will ignore */
942         if (dev->flags & IFF_NOARP ||
943             skb->pkt_type == PACKET_OTHERHOST ||
944             skb->pkt_type == PACKET_LOOPBACK)
945                 goto consumeskb;
946 
947         skb = skb_share_check(skb, GFP_ATOMIC);
948         if (!skb)
949                 goto out_of_mem;
950 
951         /* ARP header, plus 2 device addresses, plus 2 IP addresses.  */
952         if (!pskb_may_pull(skb, arp_hdr_len(dev)))
953                 goto freeskb;
954 
955         arp = arp_hdr(skb);
956         if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4)
957                 goto freeskb;
958 
959         memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
960 
961         return NF_HOOK(NFPROTO_ARP, NF_ARP_IN,
962                        dev_net(dev), NULL, skb, dev, NULL,
963                        arp_process);
964 
965 consumeskb:
966         consume_skb(skb);
967         return NET_RX_SUCCESS;
968 freeskb:
969         kfree_skb(skb);
970 out_of_mem:
971         return NET_RX_DROP;
972 }
973 
974 /*
975  *      User level interface (ioctl)
976  */
977 
978 /*
979  *      Set (create) an ARP cache entry.
980  */
981 
982 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
983 {
984         if (!dev) {
985                 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
986                 return 0;
987         }
988         if (__in_dev_get_rtnl(dev)) {
989                 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
990                 return 0;
991         }
992         return -ENXIO;
993 }
994 
995 static int arp_req_set_public(struct net *net, struct arpreq *r,
996                 struct net_device *dev)
997 {
998         __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
999         __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1000 
1001         if (mask && mask != htonl(0xFFFFFFFF))
1002                 return -EINVAL;
1003         if (!dev && (r->arp_flags & ATF_COM)) {
1004                 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family,
1005                                       r->arp_ha.sa_data);
1006                 if (!dev)
1007                         return -ENODEV;
1008         }
1009         if (mask) {
1010                 if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1))
1011                         return -ENOBUFS;
1012                 return 0;
1013         }
1014 
1015         return arp_req_set_proxy(net, dev, 1);
1016 }
1017 
1018 static int arp_req_set(struct net *net, struct arpreq *r,
1019                        struct net_device *dev)
1020 {
1021         __be32 ip;
1022         struct neighbour *neigh;
1023         int err;
1024 
1025         if (r->arp_flags & ATF_PUBL)
1026                 return arp_req_set_public(net, r, dev);
1027 
1028         ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1029         if (r->arp_flags & ATF_PERM)
1030                 r->arp_flags |= ATF_COM;
1031         if (!dev) {
1032                 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1033 
1034                 if (IS_ERR(rt))
1035                         return PTR_ERR(rt);
1036                 dev = rt->dst.dev;
1037                 ip_rt_put(rt);
1038                 if (!dev)
1039                         return -EINVAL;
1040         }
1041         switch (dev->type) {
1042 #if IS_ENABLED(CONFIG_FDDI)
1043         case ARPHRD_FDDI:
1044                 /*
1045                  * According to RFC 1390, FDDI devices should accept ARP
1046                  * hardware types of 1 (Ethernet).  However, to be more
1047                  * robust, we'll accept hardware types of either 1 (Ethernet)
1048                  * or 6 (IEEE 802.2).
1049                  */
1050                 if (r->arp_ha.sa_family != ARPHRD_FDDI &&
1051                     r->arp_ha.sa_family != ARPHRD_ETHER &&
1052                     r->arp_ha.sa_family != ARPHRD_IEEE802)
1053                         return -EINVAL;
1054                 break;
1055 #endif
1056         default:
1057                 if (r->arp_ha.sa_family != dev->type)
1058                         return -EINVAL;
1059                 break;
1060         }
1061 
1062         neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
1063         err = PTR_ERR(neigh);
1064         if (!IS_ERR(neigh)) {
1065                 unsigned int state = NUD_STALE;
1066                 if (r->arp_flags & ATF_PERM)
1067                         state = NUD_PERMANENT;
1068                 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ?
1069                                    r->arp_ha.sa_data : NULL, state,
1070                                    NEIGH_UPDATE_F_OVERRIDE |
1071                                    NEIGH_UPDATE_F_ADMIN, 0);
1072                 neigh_release(neigh);
1073         }
1074         return err;
1075 }
1076 
1077 static unsigned int arp_state_to_flags(struct neighbour *neigh)
1078 {
1079         if (neigh->nud_state&NUD_PERMANENT)
1080                 return ATF_PERM | ATF_COM;
1081         else if (neigh->nud_state&NUD_VALID)
1082                 return ATF_COM;
1083         else
1084                 return 0;
1085 }
1086 
1087 /*
1088  *      Get an ARP cache entry.
1089  */
1090 
1091 static int arp_req_get(struct arpreq *r, struct net_device *dev)
1092 {
1093         __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1094         struct neighbour *neigh;
1095         int err = -ENXIO;
1096 
1097         neigh = neigh_lookup(&arp_tbl, &ip, dev);
1098         if (neigh) {
1099                 if (!(neigh->nud_state & NUD_NOARP)) {
1100                         read_lock_bh(&neigh->lock);
1101                         memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
1102                         r->arp_flags = arp_state_to_flags(neigh);
1103                         read_unlock_bh(&neigh->lock);
1104                         r->arp_ha.sa_family = dev->type;
1105                         strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
1106                         err = 0;
1107                 }
1108                 neigh_release(neigh);
1109         }
1110         return err;
1111 }
1112 
1113 static int arp_invalidate(struct net_device *dev, __be32 ip)
1114 {
1115         struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
1116         int err = -ENXIO;
1117         struct neigh_table *tbl = &arp_tbl;
1118 
1119         if (neigh) {
1120                 if (neigh->nud_state & ~NUD_NOARP)
1121                         err = neigh_update(neigh, NULL, NUD_FAILED,
1122                                            NEIGH_UPDATE_F_OVERRIDE|
1123                                            NEIGH_UPDATE_F_ADMIN, 0);
1124                 write_lock_bh(&tbl->lock);
1125                 neigh_release(neigh);
1126                 neigh_remove_one(neigh, tbl);
1127                 write_unlock_bh(&tbl->lock);
1128         }
1129 
1130         return err;
1131 }
1132 
1133 static int arp_req_delete_public(struct net *net, struct arpreq *r,
1134                 struct net_device *dev)
1135 {
1136         __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
1137         __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
1138 
1139         if (mask == htonl(0xFFFFFFFF))
1140                 return pneigh_delete(&arp_tbl, net, &ip, dev);
1141 
1142         if (mask)
1143                 return -EINVAL;
1144 
1145         return arp_req_set_proxy(net, dev, 0);
1146 }
1147 
1148 static int arp_req_delete(struct net *net, struct arpreq *r,
1149                           struct net_device *dev)
1150 {
1151         __be32 ip;
1152 
1153         if (r->arp_flags & ATF_PUBL)
1154                 return arp_req_delete_public(net, r, dev);
1155 
1156         ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
1157         if (!dev) {
1158                 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
1159                 if (IS_ERR(rt))
1160                         return PTR_ERR(rt);
1161                 dev = rt->dst.dev;
1162                 ip_rt_put(rt);
1163                 if (!dev)
1164                         return -EINVAL;
1165         }
1166         return arp_invalidate(dev, ip);
1167 }
1168 
1169 /*
1170  *      Handle an ARP layer I/O control request.
1171  */
1172 
1173 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
1174 {
1175         int err;
1176         struct arpreq r;
1177         struct net_device *dev = NULL;
1178 
1179         switch (cmd) {
1180         case SIOCDARP:
1181         case SIOCSARP:
1182                 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1183                         return -EPERM;
1184                 /* fall through */
1185         case SIOCGARP:
1186                 err = copy_from_user(&r, arg, sizeof(struct arpreq));
1187                 if (err)
1188                         return -EFAULT;
1189                 break;
1190         default:
1191                 return -EINVAL;
1192         }
1193 
1194         if (r.arp_pa.sa_family != AF_INET)
1195                 return -EPFNOSUPPORT;
1196 
1197         if (!(r.arp_flags & ATF_PUBL) &&
1198             (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
1199                 return -EINVAL;
1200         if (!(r.arp_flags & ATF_NETMASK))
1201                 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
1202                                                            htonl(0xFFFFFFFFUL);
1203         rtnl_lock();
1204         if (r.arp_dev[0]) {
1205                 err = -ENODEV;
1206                 dev = __dev_get_by_name(net, r.arp_dev);
1207                 if (!dev)
1208                         goto out;
1209 
1210                 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
1211                 if (!r.arp_ha.sa_family)
1212                         r.arp_ha.sa_family = dev->type;
1213                 err = -EINVAL;
1214                 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
1215                         goto out;
1216         } else if (cmd == SIOCGARP) {
1217                 err = -ENODEV;
1218                 goto out;
1219         }
1220 
1221         switch (cmd) {
1222         case SIOCDARP:
1223                 err = arp_req_delete(net, &r, dev);
1224                 break;
1225         case SIOCSARP:
1226                 err = arp_req_set(net, &r, dev);
1227                 break;
1228         case SIOCGARP:
1229                 err = arp_req_get(&r, dev);
1230                 break;
1231         }
1232 out:
1233         rtnl_unlock();
1234         if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
1235                 err = -EFAULT;
1236         return err;
1237 }
1238 
1239 static int arp_netdev_event(struct notifier_block *this, unsigned long event,
1240                             void *ptr)
1241 {
1242         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
1243         struct netdev_notifier_change_info *change_info;
1244 
1245         switch (event) {
1246         case NETDEV_CHANGEADDR:
1247                 neigh_changeaddr(&arp_tbl, dev);
1248                 rt_cache_flush(dev_net(dev));
1249                 break;
1250         case NETDEV_CHANGE:
1251                 change_info = ptr;
1252                 if (change_info->flags_changed & IFF_NOARP)
1253                         neigh_changeaddr(&arp_tbl, dev);
1254                 if (!netif_carrier_ok(dev))
1255                         neigh_carrier_down(&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(NEIGH_ARP_TABLE, &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 void 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                 buf[0] = '*';
1332                 buf[1] = '\0';
1333         }
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%-17s     *        %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 /* ------------------------------------------------------------------------ */
1420 
1421 static int __net_init arp_net_init(struct net *net)
1422 {
1423         if (!proc_create_net("arp", 0444, net->proc_net, &arp_seq_ops,
1424                         sizeof(struct neigh_seq_state)))
1425                 return -ENOMEM;
1426         return 0;
1427 }
1428 
1429 static void __net_exit arp_net_exit(struct net *net)
1430 {
1431         remove_proc_entry("arp", net->proc_net);
1432 }
1433 
1434 static struct pernet_operations arp_net_ops = {
1435         .init = arp_net_init,
1436         .exit = arp_net_exit,
1437 };
1438 
1439 static int __init arp_proc_init(void)
1440 {
1441         return register_pernet_subsys(&arp_net_ops);
1442 }
1443 
1444 #else /* CONFIG_PROC_FS */
1445 
1446 static int __init arp_proc_init(void)
1447 {
1448         return 0;
1449 }
1450 
1451 #endif /* CONFIG_PROC_FS */
1452 

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