net/ipv4/arp.c

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
arp_mc_map
arp_hash
arp_key_eq
arp_constructor
arp_error_report
arp_send_dst
arp_send
arp_solicit
arp_ignore
arp_filter
arp_fwd_proxy
arp_fwd_pvlan
arp_create
arp_xmit_finish
arp_xmit
arp_is_garp
arp_process
parp_redo
arp_rcv
arp_req_set_proxy
arp_req_set_public
arp_req_set
arp_state_to_flags
arp_req_get
arp_invalidate
arp_req_delete_public
arp_req_delete
arp_ioctl
arp_netdev_event
arp_ifdown
arp_init
ax2asc2
arp_format_neigh_entry
arp_format_pneigh_entry
arp_seq_show
arp_seq_start
arp_net_init
arp_net_exit
arp_proc_init
arp_proc_init
   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 + '0';
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 */
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root/net/ipv4/arp.c

DEFINITIONS
