1 /* linux/net/ipv4/arp.c 2 * 3 * Copyright (C) 1994 by Florian La Roche 4 * 5 * This module implements the Address Resolution Protocol ARP (RFC 826), 6 * which is used to convert IP addresses (or in the future maybe other 7 * high-level addresses) into a low-level hardware address (like an Ethernet 8 * address). 9 * 10 * This program is free software; you can redistribute it and/or 11 * modify it under the terms of the GNU General Public License 12 * as published by the Free Software Foundation; either version 13 * 2 of the License, or (at your option) any later version. 14 * 15 * Fixes: 16 * Alan Cox : Removed the Ethernet assumptions in 17 * Florian's code 18 * Alan Cox : Fixed some small errors in the ARP 19 * logic 20 * Alan Cox : Allow >4K in /proc 21 * Alan Cox : Make ARP add its own protocol entry 22 * Ross Martin : Rewrote arp_rcv() and arp_get_info() 23 * Stephen Henson : Add AX25 support to arp_get_info() 24 * Alan Cox : Drop data when a device is downed. 25 * Alan Cox : Use init_timer(). 26 * Alan Cox : Double lock fixes. 27 * Martin Seine : Move the arphdr structure 28 * to if_arp.h for compatibility. 29 * with BSD based programs. 30 * Andrew Tridgell : Added ARP netmask code and 31 * re-arranged proxy handling. 32 * Alan Cox : Changed to use notifiers. 33 * Niibe Yutaka : Reply for this device or proxies only. 34 * Alan Cox : Don't proxy across hardware types! 35 * Jonathan Naylor : Added support for NET/ROM. 36 * Mike Shaver : RFC1122 checks. 37 * Jonathan Naylor : Only lookup the hardware address for 38 * the correct hardware type. 39 * Germano Caronni : Assorted subtle races. 40 * Craig Schlenter : Don't modify permanent entry 41 * during arp_rcv. 42 * Russ Nelson : Tidied up a few bits. 43 * Alexey Kuznetsov: Major changes to caching and behaviour, 44 * eg intelligent arp probing and 45 * generation 46 * of host down events. 47 * Alan Cox : Missing unlock in device events. 48 * Eckes : ARP ioctl control errors. 49 * Alexey Kuznetsov: Arp free fix. 50 * Manuel Rodriguez: Gratuitous ARP. 51 * Jonathan Layes : Added arpd support through kerneld 52 * message queue (960314) 53 * Mike Shaver : /proc/sys/net/ipv4/arp_* support 54 * Mike McLagan : Routing by source 55 * Stuart Cheshire : Metricom and grat arp fixes 56 * *** FOR 2.1 clean this up *** 57 * Lawrence V. Stefani: (08/12/96) Added FDDI support. 58 * Alan Cox : Took the AP1000 nasty FDDI hack and 59 * folded into the mainstream FDDI code. 60 * Ack spit, Linus how did you allow that 61 * one in... 62 * Jes Sorensen : Make FDDI work again in 2.1.x and 63 * clean up the APFDDI & gen. FDDI bits. 64 * Alexey Kuznetsov: new arp state machine; 65 * now it is in net/core/neighbour.c. 66 * Krzysztof Halasa: Added Frame Relay ARP support. 67 * Arnaldo C. Melo : convert /proc/net/arp to seq_file 68 * Shmulik Hen: Split arp_send to arp_create and 69 * arp_xmit so intermediate drivers like 70 * bonding can change the skb before 71 * sending (e.g. insert 8021q tag). 72 * Harald Welte : convert to make use of jenkins hash 73 * Jesper D. Brouer: Proxy ARP PVLAN RFC 3069 support. 74 */ 75 76 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 77 78 #include <linux/module.h> 79 #include <linux/types.h> 80 #include <linux/string.h> 81 #include <linux/kernel.h> 82 #include <linux/capability.h> 83 #include <linux/socket.h> 84 #include <linux/sockios.h> 85 #include <linux/errno.h> 86 #include <linux/in.h> 87 #include <linux/mm.h> 88 #include <linux/inet.h> 89 #include <linux/inetdevice.h> 90 #include <linux/netdevice.h> 91 #include <linux/etherdevice.h> 92 #include <linux/fddidevice.h> 93 #include <linux/if_arp.h> 94 #include <linux/skbuff.h> 95 #include <linux/proc_fs.h> 96 #include <linux/seq_file.h> 97 #include <linux/stat.h> 98 #include <linux/init.h> 99 #include <linux/net.h> 100 #include <linux/rcupdate.h> 101 #include <linux/slab.h> 102 #ifdef CONFIG_SYSCTL 103 #include <linux/sysctl.h> 104 #endif 105 106 #include <net/net_namespace.h> 107 #include <net/ip.h> 108 #include <net/icmp.h> 109 #include <net/route.h> 110 #include <net/protocol.h> 111 #include <net/tcp.h> 112 #include <net/sock.h> 113 #include <net/arp.h> 114 #include <net/ax25.h> 115 #include <net/netrom.h> 116 117 #include <linux/uaccess.h> 118 119 #include <linux/netfilter_arp.h> 120 121 /* 122 * Interface to generic neighbour cache. 123 */ 124 static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd); 125 static bool arp_key_eq(const struct neighbour *n, const void *pkey); 126 static int arp_constructor(struct neighbour *neigh); 127 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb); 128 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb); 129 static void parp_redo(struct sk_buff *skb); 130 131 static const struct neigh_ops arp_generic_ops = { 132 .family = AF_INET, 133 .solicit = arp_solicit, 134 .error_report = arp_error_report, 135 .output = neigh_resolve_output, 136 .connected_output = neigh_connected_output, 137 }; 138 139 static const struct neigh_ops arp_hh_ops = { 140 .family = AF_INET, 141 .solicit = arp_solicit, 142 .error_report = arp_error_report, 143 .output = neigh_resolve_output, 144 .connected_output = neigh_resolve_output, 145 }; 146 147 static const struct neigh_ops arp_direct_ops = { 148 .family = AF_INET, 149 .output = neigh_direct_output, 150 .connected_output = neigh_direct_output, 151 }; 152 153 struct neigh_table arp_tbl = { 154 .family = AF_INET, 155 .key_len = 4, 156 .protocol = cpu_to_be16(ETH_P_IP), 157 .hash = arp_hash, 158 .key_eq = arp_key_eq, 159 .constructor = arp_constructor, 160 .proxy_redo = parp_redo, 161 .id = "arp_cache", 162 .parms = { 163 .tbl = &arp_tbl, 164 .reachable_time = 30 * HZ, 165 .data = { 166 [NEIGH_VAR_MCAST_PROBES] = 3, 167 [NEIGH_VAR_UCAST_PROBES] = 3, 168 [NEIGH_VAR_RETRANS_TIME] = 1 * HZ, 169 [NEIGH_VAR_BASE_REACHABLE_TIME] = 30 * HZ, 170 [NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ, 171 [NEIGH_VAR_GC_STALETIME] = 60 * HZ, 172 [NEIGH_VAR_QUEUE_LEN_BYTES] = 64 * 1024, 173 [NEIGH_VAR_PROXY_QLEN] = 64, 174 [NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ, 175 [NEIGH_VAR_PROXY_DELAY] = (8 * HZ) / 10, 176 [NEIGH_VAR_LOCKTIME] = 1 * HZ, 177 }, 178 }, 179 .gc_interval = 30 * HZ, 180 .gc_thresh1 = 128, 181 .gc_thresh2 = 512, 182 .gc_thresh3 = 1024, 183 }; 184 EXPORT_SYMBOL(arp_tbl); 185 186 int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir) 187 { 188 switch (dev->type) { 189 case ARPHRD_ETHER: 190 case ARPHRD_FDDI: 191 case ARPHRD_IEEE802: 192 ip_eth_mc_map(addr, haddr); 193 return 0; 194 case ARPHRD_INFINIBAND: 195 ip_ib_mc_map(addr, dev->broadcast, haddr); 196 return 0; 197 case ARPHRD_IPGRE: 198 ip_ipgre_mc_map(addr, dev->broadcast, haddr); 199 return 0; 200 default: 201 if (dir) { 202 memcpy(haddr, dev->broadcast, dev->addr_len); 203 return 0; 204 } 205 } 206 return -EINVAL; 207 } 208 209 210 static u32 arp_hash(const void *pkey, 211 const struct net_device *dev, 212 __u32 *hash_rnd) 213 { 214 return arp_hashfn(pkey, dev, hash_rnd); 215 } 216 217 static bool arp_key_eq(const struct neighbour *neigh, const void *pkey) 218 { 219 return neigh_key_eq32(neigh, pkey); 220 } 221 222 static int arp_constructor(struct neighbour *neigh) 223 { 224 __be32 addr = *(__be32 *)neigh->primary_key; 225 struct net_device *dev = neigh->dev; 226 struct in_device *in_dev; 227 struct neigh_parms *parms; 228 229 rcu_read_lock(); 230 in_dev = __in_dev_get_rcu(dev); 231 if (!in_dev) { 232 rcu_read_unlock(); 233 return -EINVAL; 234 } 235 236 neigh->type = inet_addr_type_dev_table(dev_net(dev), dev, addr); 237 238 parms = in_dev->arp_parms; 239 __neigh_parms_put(neigh->parms); 240 neigh->parms = neigh_parms_clone(parms); 241 rcu_read_unlock(); 242 243 if (!dev->header_ops) { 244 neigh->nud_state = NUD_NOARP; 245 neigh->ops = &arp_direct_ops; 246 neigh->output = neigh_direct_output; 247 } else { 248 /* Good devices (checked by reading texts, but only Ethernet is 249 tested) 250 251 ARPHRD_ETHER: (ethernet, apfddi) 252 ARPHRD_FDDI: (fddi) 253 ARPHRD_IEEE802: (tr) 254 ARPHRD_METRICOM: (strip) 255 ARPHRD_ARCNET: 256 etc. etc. etc. 257 258 ARPHRD_IPDDP will also work, if author repairs it. 259 I did not it, because this driver does not work even 260 in old paradigm. 261 */ 262 263 if (neigh->type == RTN_MULTICAST) { 264 neigh->nud_state = NUD_NOARP; 265 arp_mc_map(addr, neigh->ha, dev, 1); 266 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) { 267 neigh->nud_state = NUD_NOARP; 268 memcpy(neigh->ha, dev->dev_addr, dev->addr_len); 269 } else if (neigh->type == RTN_BROADCAST || 270 (dev->flags & IFF_POINTOPOINT)) { 271 neigh->nud_state = NUD_NOARP; 272 memcpy(neigh->ha, dev->broadcast, dev->addr_len); 273 } 274 275 if (dev->header_ops->cache) 276 neigh->ops = &arp_hh_ops; 277 else 278 neigh->ops = &arp_generic_ops; 279 280 if (neigh->nud_state & NUD_VALID) 281 neigh->output = neigh->ops->connected_output; 282 else 283 neigh->output = neigh->ops->output; 284 } 285 return 0; 286 } 287 288 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb) 289 { 290 dst_link_failure(skb); 291 kfree_skb(skb); 292 } 293 294 /* Create and send an arp packet. */ 295 static void arp_send_dst(int type, int ptype, __be32 dest_ip, 296 struct net_device *dev, __be32 src_ip, 297 const unsigned char *dest_hw, 298 const unsigned char *src_hw, 299 const unsigned char *target_hw, struct sk_buff *oskb) 300 { 301 struct sk_buff *skb; 302 303 /* arp on this interface. */ 304 if (dev->flags & IFF_NOARP) 305 return; 306 307 skb = arp_create(type, ptype, dest_ip, dev, src_ip, 308 dest_hw, src_hw, target_hw); 309 if (!skb) 310 return; 311 312 if (oskb) 313 skb_dst_copy(skb, oskb); 314 315 arp_xmit(skb); 316 } 317 318 void arp_send(int type, int ptype, __be32 dest_ip, 319 struct net_device *dev, __be32 src_ip, 320 const unsigned char *dest_hw, const unsigned char *src_hw, 321 const unsigned char *target_hw) 322 { 323 arp_send_dst(type, ptype, dest_ip, dev, src_ip, dest_hw, src_hw, 324 target_hw, NULL); 325 } 326 EXPORT_SYMBOL(arp_send); 327 328 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb) 329 { 330 __be32 saddr = 0; 331 u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL; 332 struct net_device *dev = neigh->dev; 333 __be32 target = *(__be32 *)neigh->primary_key; 334 int probes = atomic_read(&neigh->probes); 335 struct in_device *in_dev; 336 337 rcu_read_lock(); 338 in_dev = __in_dev_get_rcu(dev); 339 if (!in_dev) { 340 rcu_read_unlock(); 341 return; 342 } 343 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) { 344 default: 345 case 0: /* By default announce any local IP */ 346 if (skb && inet_addr_type_dev_table(dev_net(dev), dev, 347 ip_hdr(skb)->saddr) == RTN_LOCAL) 348 saddr = ip_hdr(skb)->saddr; 349 break; 350 case 1: /* Restrict announcements of saddr in same subnet */ 351 if (!skb) 352 break; 353 saddr = ip_hdr(skb)->saddr; 354 if (inet_addr_type_dev_table(dev_net(dev), dev, 355 saddr) == RTN_LOCAL) { 356 /* saddr should be known to target */ 357 if (inet_addr_onlink(in_dev, target, saddr)) 358 break; 359 } 360 saddr = 0; 361 break; 362 case 2: /* Avoid secondary IPs, get a primary/preferred one */ 363 break; 364 } 365 rcu_read_unlock(); 366 367 if (!saddr) 368 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK); 369 370 probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES); 371 if (probes < 0) { 372 if (!(neigh->nud_state & NUD_VALID)) 373 pr_debug("trying to ucast probe in NUD_INVALID\n"); 374 neigh_ha_snapshot(dst_ha, neigh, dev); 375 dst_hw = dst_ha; 376 } else { 377 probes -= NEIGH_VAR(neigh->parms, APP_PROBES); 378 if (probes < 0) { 379 neigh_app_ns(neigh); 380 return; 381 } 382 } 383 384 arp_send_dst(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr, 385 dst_hw, dev->dev_addr, NULL, 386 dev->priv_flags & IFF_XMIT_DST_RELEASE ? NULL : skb); 387 } 388 389 static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip) 390 { 391 struct net *net = dev_net(in_dev->dev); 392 int scope; 393 394 switch (IN_DEV_ARP_IGNORE(in_dev)) { 395 case 0: /* Reply, the tip is already validated */ 396 return 0; 397 case 1: /* Reply only if tip is configured on the incoming interface */ 398 sip = 0; 399 scope = RT_SCOPE_HOST; 400 break; 401 case 2: /* 402 * Reply only if tip is configured on the incoming interface 403 * and is in same subnet as sip 404 */ 405 scope = RT_SCOPE_HOST; 406 break; 407 case 3: /* Do not reply for scope host addresses */ 408 sip = 0; 409 scope = RT_SCOPE_LINK; 410 in_dev = NULL; 411 break; 412 case 4: /* Reserved */ 413 case 5: 414 case 6: 415 case 7: 416 return 0; 417 case 8: /* Do not reply */ 418 return 1; 419 default: 420 return 0; 421 } 422 return !inet_confirm_addr(net, in_dev, sip, tip, scope); 423 } 424 425 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev) 426 { 427 struct rtable *rt; 428 int flag = 0; 429 /*unsigned long now; */ 430 struct net *net = dev_net(dev); 431 432 rt = ip_route_output(net, sip, tip, 0, 0); 433 if (IS_ERR(rt)) 434 return 1; 435 if (rt->dst.dev != dev) { 436 NET_INC_STATS_BH(net, LINUX_MIB_ARPFILTER); 437 flag = 1; 438 } 439 ip_rt_put(rt); 440 return flag; 441 } 442 443 /* 444 * Check if we can use proxy ARP for this path 445 */ 446 static inline int arp_fwd_proxy(struct in_device *in_dev, 447 struct net_device *dev, struct rtable *rt) 448 { 449 struct in_device *out_dev; 450 int imi, omi = -1; 451 452 if (rt->dst.dev == dev) 453 return 0; 454 455 if (!IN_DEV_PROXY_ARP(in_dev)) 456 return 0; 457 imi = IN_DEV_MEDIUM_ID(in_dev); 458 if (imi == 0) 459 return 1; 460 if (imi == -1) 461 return 0; 462 463 /* place to check for proxy_arp for routes */ 464 465 out_dev = __in_dev_get_rcu(rt->dst.dev); 466 if (out_dev) 467 omi = IN_DEV_MEDIUM_ID(out_dev); 468 469 return omi != imi && omi != -1; 470 } 471 472 /* 473 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev) 474 * 475 * RFC3069 supports proxy arp replies back to the same interface. This 476 * is done to support (ethernet) switch features, like RFC 3069, where 477 * the individual ports are not allowed to communicate with each 478 * other, BUT they are allowed to talk to the upstream router. As 479 * described in RFC 3069, it is possible to allow these hosts to 480 * communicate through the upstream router, by proxy_arp'ing. 481 * 482 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation" 483 * 484 * This technology is known by different names: 485 * In RFC 3069 it is called VLAN Aggregation. 486 * Cisco and Allied Telesyn call it Private VLAN. 487 * Hewlett-Packard call it Source-Port filtering or port-isolation. 488 * Ericsson call it MAC-Forced Forwarding (RFC Draft). 489 * 490 */ 491 static inline int arp_fwd_pvlan(struct in_device *in_dev, 492 struct net_device *dev, struct rtable *rt, 493 __be32 sip, __be32 tip) 494 { 495 /* Private VLAN is only concerned about the same ethernet segment */ 496 if (rt->dst.dev != dev) 497 return 0; 498 499 /* Don't reply on self probes (often done by windowz boxes)*/ 500 if (sip == tip) 501 return 0; 502 503 if (IN_DEV_PROXY_ARP_PVLAN(in_dev)) 504 return 1; 505 else 506 return 0; 507 } 508 509 /* 510 * Interface to link layer: send routine and receive handler. 511 */ 512 513 /* 514 * Create an arp packet. If dest_hw is not set, we create a broadcast 515 * message. 516 */ 517 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip, 518 struct net_device *dev, __be32 src_ip, 519 const unsigned char *dest_hw, 520 const unsigned char *src_hw, 521 const unsigned char *target_hw) 522 { 523 struct sk_buff *skb; 524 struct arphdr *arp; 525 unsigned char *arp_ptr; 526 int hlen = LL_RESERVED_SPACE(dev); 527 int tlen = dev->needed_tailroom; 528 529 /* 530 * Allocate a buffer 531 */ 532 533 skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC); 534 if (!skb) 535 return NULL; 536 537 skb_reserve(skb, hlen); 538 skb_reset_network_header(skb); 539 arp = (struct arphdr *) skb_put(skb, arp_hdr_len(dev)); 540 skb->dev = dev; 541 skb->protocol = htons(ETH_P_ARP); 542 if (!src_hw) 543 src_hw = dev->dev_addr; 544 if (!dest_hw) 545 dest_hw = dev->broadcast; 546 547 /* 548 * Fill the device header for the ARP frame 549 */ 550 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0) 551 goto out; 552 553 /* 554 * Fill out the arp protocol part. 555 * 556 * The arp hardware type should match the device type, except for FDDI, 557 * which (according to RFC 1390) should always equal 1 (Ethernet). 558 */ 559 /* 560 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the 561 * DIX code for the protocol. Make these device structure fields. 562 */ 563 switch (dev->type) { 564 default: 565 arp->ar_hrd = htons(dev->type); 566 arp->ar_pro = htons(ETH_P_IP); 567 break; 568 569 #if IS_ENABLED(CONFIG_AX25) 570 case ARPHRD_AX25: 571 arp->ar_hrd = htons(ARPHRD_AX25); 572 arp->ar_pro = htons(AX25_P_IP); 573 break; 574 575 #if IS_ENABLED(CONFIG_NETROM) 576 case ARPHRD_NETROM: 577 arp->ar_hrd = htons(ARPHRD_NETROM); 578 arp->ar_pro = htons(AX25_P_IP); 579 break; 580 #endif 581 #endif 582 583 #if IS_ENABLED(CONFIG_FDDI) 584 case ARPHRD_FDDI: 585 arp->ar_hrd = htons(ARPHRD_ETHER); 586 arp->ar_pro = htons(ETH_P_IP); 587 break; 588 #endif 589 } 590 591 arp->ar_hln = dev->addr_len; 592 arp->ar_pln = 4; 593 arp->ar_op = htons(type); 594 595 arp_ptr = (unsigned char *)(arp + 1); 596 597 memcpy(arp_ptr, src_hw, dev->addr_len); 598 arp_ptr += dev->addr_len; 599 memcpy(arp_ptr, &src_ip, 4); 600 arp_ptr += 4; 601 602 switch (dev->type) { 603 #if IS_ENABLED(CONFIG_FIREWIRE_NET) 604 case ARPHRD_IEEE1394: 605 break; 606 #endif 607 default: 608 if (target_hw) 609 memcpy(arp_ptr, target_hw, dev->addr_len); 610 else 611 memset(arp_ptr, 0, dev->addr_len); 612 arp_ptr += dev->addr_len; 613 } 614 memcpy(arp_ptr, &dest_ip, 4); 615 616 return skb; 617 618 out: 619 kfree_skb(skb); 620 return NULL; 621 } 622 EXPORT_SYMBOL(arp_create); 623 624 /* 625 * Send an arp packet. 626 */ 627 void arp_xmit(struct sk_buff *skb) 628 { 629 /* Send it off, maybe filter it using firewalling first. */ 630 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, NULL, skb, 631 NULL, skb->dev, dev_queue_xmit_sk); 632 } 633 EXPORT_SYMBOL(arp_xmit); 634 635 /* 636 * Process an arp request. 637 */ 638 639 static int arp_process(struct sock *sk, struct sk_buff *skb) 640 { 641 struct net_device *dev = skb->dev; 642 struct in_device *in_dev = __in_dev_get_rcu(dev); 643 struct arphdr *arp; 644 unsigned char *arp_ptr; 645 struct rtable *rt; 646 unsigned char *sha; 647 __be32 sip, tip; 648 u16 dev_type = dev->type; 649 int addr_type; 650 struct neighbour *n; 651 struct net *net = dev_net(dev); 652 bool is_garp = false; 653 654 /* arp_rcv below verifies the ARP header and verifies the device 655 * is ARP'able. 656 */ 657 658 if (!in_dev) 659 goto out; 660 661 arp = arp_hdr(skb); 662 663 switch (dev_type) { 664 default: 665 if (arp->ar_pro != htons(ETH_P_IP) || 666 htons(dev_type) != arp->ar_hrd) 667 goto out; 668 break; 669 case ARPHRD_ETHER: 670 case ARPHRD_FDDI: 671 case ARPHRD_IEEE802: 672 /* 673 * ETHERNET, and Fibre Channel (which are IEEE 802 674 * devices, according to RFC 2625) devices will accept ARP 675 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2). 676 * This is the case also of FDDI, where the RFC 1390 says that 677 * FDDI devices should accept ARP hardware of (1) Ethernet, 678 * however, to be more robust, we'll accept both 1 (Ethernet) 679 * or 6 (IEEE 802.2) 680 */ 681 if ((arp->ar_hrd != htons(ARPHRD_ETHER) && 682 arp->ar_hrd != htons(ARPHRD_IEEE802)) || 683 arp->ar_pro != htons(ETH_P_IP)) 684 goto out; 685 break; 686 case ARPHRD_AX25: 687 if (arp->ar_pro != htons(AX25_P_IP) || 688 arp->ar_hrd != htons(ARPHRD_AX25)) 689 goto out; 690 break; 691 case ARPHRD_NETROM: 692 if (arp->ar_pro != htons(AX25_P_IP) || 693 arp->ar_hrd != htons(ARPHRD_NETROM)) 694 goto out; 695 break; 696 } 697 698 /* Understand only these message types */ 699 700 if (arp->ar_op != htons(ARPOP_REPLY) && 701 arp->ar_op != htons(ARPOP_REQUEST)) 702 goto out; 703 704 /* 705 * Extract fields 706 */ 707 arp_ptr = (unsigned char *)(arp + 1); 708 sha = arp_ptr; 709 arp_ptr += dev->addr_len; 710 memcpy(&sip, arp_ptr, 4); 711 arp_ptr += 4; 712 switch (dev_type) { 713 #if IS_ENABLED(CONFIG_FIREWIRE_NET) 714 case ARPHRD_IEEE1394: 715 break; 716 #endif 717 default: 718 arp_ptr += dev->addr_len; 719 } 720 memcpy(&tip, arp_ptr, 4); 721 /* 722 * Check for bad requests for 127.x.x.x and requests for multicast 723 * addresses. If this is one such, delete it. 724 */ 725 if (ipv4_is_multicast(tip) || 726 (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip))) 727 goto out; 728 729 /* 730 * Special case: We must set Frame Relay source Q.922 address 731 */ 732 if (dev_type == ARPHRD_DLCI) 733 sha = dev->broadcast; 734 735 /* 736 * Process entry. The idea here is we want to send a reply if it is a 737 * request for us or if it is a request for someone else that we hold 738 * a proxy for. We want to add an entry to our cache if it is a reply 739 * to us or if it is a request for our address. 740 * (The assumption for this last is that if someone is requesting our 741 * address, they are probably intending to talk to us, so it saves time 742 * if we cache their address. Their address is also probably not in 743 * our cache, since ours is not in their cache.) 744 * 745 * Putting this another way, we only care about replies if they are to 746 * us, in which case we add them to the cache. For requests, we care 747 * about those for us and those for our proxies. We reply to both, 748 * and in the case of requests for us we add the requester to the arp 749 * cache. 750 */ 751 752 /* Special case: IPv4 duplicate address detection packet (RFC2131) */ 753 if (sip == 0) { 754 if (arp->ar_op == htons(ARPOP_REQUEST) && 755 inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL && 756 !arp_ignore(in_dev, sip, tip)) 757 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, sha, 758 dev->dev_addr, sha); 759 goto out; 760 } 761 762 if (arp->ar_op == htons(ARPOP_REQUEST) && 763 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) { 764 765 rt = skb_rtable(skb); 766 addr_type = rt->rt_type; 767 768 if (addr_type == RTN_LOCAL) { 769 int dont_send; 770 771 dont_send = arp_ignore(in_dev, sip, tip); 772 if (!dont_send && IN_DEV_ARPFILTER(in_dev)) 773 dont_send = arp_filter(sip, tip, dev); 774 if (!dont_send) { 775 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 776 if (n) { 777 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, 778 dev, tip, sha, dev->dev_addr, 779 sha); 780 neigh_release(n); 781 } 782 } 783 goto out; 784 } else if (IN_DEV_FORWARD(in_dev)) { 785 if (addr_type == RTN_UNICAST && 786 (arp_fwd_proxy(in_dev, dev, rt) || 787 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) || 788 (rt->dst.dev != dev && 789 pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) { 790 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 791 if (n) 792 neigh_release(n); 793 794 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED || 795 skb->pkt_type == PACKET_HOST || 796 NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) { 797 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, 798 dev, tip, sha, dev->dev_addr, 799 sha); 800 } else { 801 pneigh_enqueue(&arp_tbl, 802 in_dev->arp_parms, skb); 803 return 0; 804 } 805 goto out; 806 } 807 } 808 } 809 810 /* Update our ARP tables */ 811 812 n = __neigh_lookup(&arp_tbl, &sip, dev, 0); 813 814 if (IN_DEV_ARP_ACCEPT(in_dev)) { 815 unsigned int addr_type = inet_addr_type_dev_table(net, dev, sip); 816 817 /* Unsolicited ARP is not accepted by default. 818 It is possible, that this option should be enabled for some 819 devices (strip is candidate) 820 */ 821 is_garp = arp->ar_op == htons(ARPOP_REQUEST) && tip == sip && 822 addr_type == RTN_UNICAST; 823 824 if (!n && 825 ((arp->ar_op == htons(ARPOP_REPLY) && 826 addr_type == RTN_UNICAST) || is_garp)) 827 n = __neigh_lookup(&arp_tbl, &sip, dev, 1); 828 } 829 830 if (n) { 831 int state = NUD_REACHABLE; 832 int override; 833 834 /* If several different ARP replies follows back-to-back, 835 use the FIRST one. It is possible, if several proxy 836 agents are active. Taking the first reply prevents 837 arp trashing and chooses the fastest router. 838 */ 839 override = time_after(jiffies, 840 n->updated + 841 NEIGH_VAR(n->parms, LOCKTIME)) || 842 is_garp; 843 844 /* Broadcast replies and request packets 845 do not assert neighbour reachability. 846 */ 847 if (arp->ar_op != htons(ARPOP_REPLY) || 848 skb->pkt_type != PACKET_HOST) 849 state = NUD_STALE; 850 neigh_update(n, sha, state, 851 override ? NEIGH_UPDATE_F_OVERRIDE : 0); 852 neigh_release(n); 853 } 854 855 out: 856 consume_skb(skb); 857 return 0; 858 } 859 860 static void parp_redo(struct sk_buff *skb) 861 { 862 arp_process(NULL, skb); 863 } 864 865 866 /* 867 * Receive an arp request from the device layer. 868 */ 869 870 static int arp_rcv(struct sk_buff *skb, struct net_device *dev, 871 struct packet_type *pt, struct net_device *orig_dev) 872 { 873 const struct arphdr *arp; 874 875 /* do not tweak dropwatch on an ARP we will ignore */ 876 if (dev->flags & IFF_NOARP || 877 skb->pkt_type == PACKET_OTHERHOST || 878 skb->pkt_type == PACKET_LOOPBACK) 879 goto consumeskb; 880 881 skb = skb_share_check(skb, GFP_ATOMIC); 882 if (!skb) 883 goto out_of_mem; 884 885 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */ 886 if (!pskb_may_pull(skb, arp_hdr_len(dev))) 887 goto freeskb; 888 889 arp = arp_hdr(skb); 890 if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4) 891 goto freeskb; 892 893 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb)); 894 895 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, NULL, skb, 896 dev, NULL, arp_process); 897 898 consumeskb: 899 consume_skb(skb); 900 return 0; 901 freeskb: 902 kfree_skb(skb); 903 out_of_mem: 904 return 0; 905 } 906 907 /* 908 * User level interface (ioctl) 909 */ 910 911 /* 912 * Set (create) an ARP cache entry. 913 */ 914 915 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on) 916 { 917 if (!dev) { 918 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on; 919 return 0; 920 } 921 if (__in_dev_get_rtnl(dev)) { 922 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on); 923 return 0; 924 } 925 return -ENXIO; 926 } 927 928 static int arp_req_set_public(struct net *net, struct arpreq *r, 929 struct net_device *dev) 930 { 931 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 932 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 933 934 if (mask && mask != htonl(0xFFFFFFFF)) 935 return -EINVAL; 936 if (!dev && (r->arp_flags & ATF_COM)) { 937 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family, 938 r->arp_ha.sa_data); 939 if (!dev) 940 return -ENODEV; 941 } 942 if (mask) { 943 if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1)) 944 return -ENOBUFS; 945 return 0; 946 } 947 948 return arp_req_set_proxy(net, dev, 1); 949 } 950 951 static int arp_req_set(struct net *net, struct arpreq *r, 952 struct net_device *dev) 953 { 954 __be32 ip; 955 struct neighbour *neigh; 956 int err; 957 958 if (r->arp_flags & ATF_PUBL) 959 return arp_req_set_public(net, r, dev); 960 961 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 962 if (r->arp_flags & ATF_PERM) 963 r->arp_flags |= ATF_COM; 964 if (!dev) { 965 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0); 966 967 if (IS_ERR(rt)) 968 return PTR_ERR(rt); 969 dev = rt->dst.dev; 970 ip_rt_put(rt); 971 if (!dev) 972 return -EINVAL; 973 } 974 switch (dev->type) { 975 #if IS_ENABLED(CONFIG_FDDI) 976 case ARPHRD_FDDI: 977 /* 978 * According to RFC 1390, FDDI devices should accept ARP 979 * hardware types of 1 (Ethernet). However, to be more 980 * robust, we'll accept hardware types of either 1 (Ethernet) 981 * or 6 (IEEE 802.2). 982 */ 983 if (r->arp_ha.sa_family != ARPHRD_FDDI && 984 r->arp_ha.sa_family != ARPHRD_ETHER && 985 r->arp_ha.sa_family != ARPHRD_IEEE802) 986 return -EINVAL; 987 break; 988 #endif 989 default: 990 if (r->arp_ha.sa_family != dev->type) 991 return -EINVAL; 992 break; 993 } 994 995 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev); 996 err = PTR_ERR(neigh); 997 if (!IS_ERR(neigh)) { 998 unsigned int state = NUD_STALE; 999 if (r->arp_flags & ATF_PERM) 1000 state = NUD_PERMANENT; 1001 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ? 1002 r->arp_ha.sa_data : NULL, state, 1003 NEIGH_UPDATE_F_OVERRIDE | 1004 NEIGH_UPDATE_F_ADMIN); 1005 neigh_release(neigh); 1006 } 1007 return err; 1008 } 1009 1010 static unsigned int arp_state_to_flags(struct neighbour *neigh) 1011 { 1012 if (neigh->nud_state&NUD_PERMANENT) 1013 return ATF_PERM | ATF_COM; 1014 else if (neigh->nud_state&NUD_VALID) 1015 return ATF_COM; 1016 else 1017 return 0; 1018 } 1019 1020 /* 1021 * Get an ARP cache entry. 1022 */ 1023 1024 static int arp_req_get(struct arpreq *r, struct net_device *dev) 1025 { 1026 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; 1027 struct neighbour *neigh; 1028 int err = -ENXIO; 1029 1030 neigh = neigh_lookup(&arp_tbl, &ip, dev); 1031 if (neigh) { 1032 if (!(neigh->nud_state & NUD_NOARP)) { 1033 read_lock_bh(&neigh->lock); 1034 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len); 1035 r->arp_flags = arp_state_to_flags(neigh); 1036 read_unlock_bh(&neigh->lock); 1037 r->arp_ha.sa_family = dev->type; 1038 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev)); 1039 err = 0; 1040 } 1041 neigh_release(neigh); 1042 } 1043 return err; 1044 } 1045 1046 static int arp_invalidate(struct net_device *dev, __be32 ip) 1047 { 1048 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev); 1049 int err = -ENXIO; 1050 1051 if (neigh) { 1052 if (neigh->nud_state & ~NUD_NOARP) 1053 err = neigh_update(neigh, NULL, NUD_FAILED, 1054 NEIGH_UPDATE_F_OVERRIDE| 1055 NEIGH_UPDATE_F_ADMIN); 1056 neigh_release(neigh); 1057 } 1058 1059 return err; 1060 } 1061 1062 static int arp_req_delete_public(struct net *net, struct arpreq *r, 1063 struct net_device *dev) 1064 { 1065 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; 1066 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 1067 1068 if (mask == htonl(0xFFFFFFFF)) 1069 return pneigh_delete(&arp_tbl, net, &ip, dev); 1070 1071 if (mask) 1072 return -EINVAL; 1073 1074 return arp_req_set_proxy(net, dev, 0); 1075 } 1076 1077 static int arp_req_delete(struct net *net, struct arpreq *r, 1078 struct net_device *dev) 1079 { 1080 __be32 ip; 1081 1082 if (r->arp_flags & ATF_PUBL) 1083 return arp_req_delete_public(net, r, dev); 1084 1085 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1086 if (!dev) { 1087 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0); 1088 if (IS_ERR(rt)) 1089 return PTR_ERR(rt); 1090 dev = rt->dst.dev; 1091 ip_rt_put(rt); 1092 if (!dev) 1093 return -EINVAL; 1094 } 1095 return arp_invalidate(dev, ip); 1096 } 1097 1098 /* 1099 * Handle an ARP layer I/O control request. 1100 */ 1101 1102 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg) 1103 { 1104 int err; 1105 struct arpreq r; 1106 struct net_device *dev = NULL; 1107 1108 switch (cmd) { 1109 case SIOCDARP: 1110 case SIOCSARP: 1111 if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) 1112 return -EPERM; 1113 case SIOCGARP: 1114 err = copy_from_user(&r, arg, sizeof(struct arpreq)); 1115 if (err) 1116 return -EFAULT; 1117 break; 1118 default: 1119 return -EINVAL; 1120 } 1121 1122 if (r.arp_pa.sa_family != AF_INET) 1123 return -EPFNOSUPPORT; 1124 1125 if (!(r.arp_flags & ATF_PUBL) && 1126 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB))) 1127 return -EINVAL; 1128 if (!(r.arp_flags & ATF_NETMASK)) 1129 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr = 1130 htonl(0xFFFFFFFFUL); 1131 rtnl_lock(); 1132 if (r.arp_dev[0]) { 1133 err = -ENODEV; 1134 dev = __dev_get_by_name(net, r.arp_dev); 1135 if (!dev) 1136 goto out; 1137 1138 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */ 1139 if (!r.arp_ha.sa_family) 1140 r.arp_ha.sa_family = dev->type; 1141 err = -EINVAL; 1142 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type) 1143 goto out; 1144 } else if (cmd == SIOCGARP) { 1145 err = -ENODEV; 1146 goto out; 1147 } 1148 1149 switch (cmd) { 1150 case SIOCDARP: 1151 err = arp_req_delete(net, &r, dev); 1152 break; 1153 case SIOCSARP: 1154 err = arp_req_set(net, &r, dev); 1155 break; 1156 case SIOCGARP: 1157 err = arp_req_get(&r, dev); 1158 break; 1159 } 1160 out: 1161 rtnl_unlock(); 1162 if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r))) 1163 err = -EFAULT; 1164 return err; 1165 } 1166 1167 static int arp_netdev_event(struct notifier_block *this, unsigned long event, 1168 void *ptr) 1169 { 1170 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 1171 struct netdev_notifier_change_info *change_info; 1172 1173 switch (event) { 1174 case NETDEV_CHANGEADDR: 1175 neigh_changeaddr(&arp_tbl, dev); 1176 rt_cache_flush(dev_net(dev)); 1177 break; 1178 case NETDEV_CHANGE: 1179 change_info = ptr; 1180 if (change_info->flags_changed & IFF_NOARP) 1181 neigh_changeaddr(&arp_tbl, dev); 1182 break; 1183 default: 1184 break; 1185 } 1186 1187 return NOTIFY_DONE; 1188 } 1189 1190 static struct notifier_block arp_netdev_notifier = { 1191 .notifier_call = arp_netdev_event, 1192 }; 1193 1194 /* Note, that it is not on notifier chain. 1195 It is necessary, that this routine was called after route cache will be 1196 flushed. 1197 */ 1198 void arp_ifdown(struct net_device *dev) 1199 { 1200 neigh_ifdown(&arp_tbl, dev); 1201 } 1202 1203 1204 /* 1205 * Called once on startup. 1206 */ 1207 1208 static struct packet_type arp_packet_type __read_mostly = { 1209 .type = cpu_to_be16(ETH_P_ARP), 1210 .func = arp_rcv, 1211 }; 1212 1213 static int arp_proc_init(void); 1214 1215 void __init arp_init(void) 1216 { 1217 neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl); 1218 1219 dev_add_pack(&arp_packet_type); 1220 arp_proc_init(); 1221 #ifdef CONFIG_SYSCTL 1222 neigh_sysctl_register(NULL, &arp_tbl.parms, NULL); 1223 #endif 1224 register_netdevice_notifier(&arp_netdev_notifier); 1225 } 1226 1227 #ifdef CONFIG_PROC_FS 1228 #if IS_ENABLED(CONFIG_AX25) 1229 1230 /* ------------------------------------------------------------------------ */ 1231 /* 1232 * ax25 -> ASCII conversion 1233 */ 1234 static char *ax2asc2(ax25_address *a, char *buf) 1235 { 1236 char c, *s; 1237 int n; 1238 1239 for (n = 0, s = buf; n < 6; n++) { 1240 c = (a->ax25_call[n] >> 1) & 0x7F; 1241 1242 if (c != ' ') 1243 *s++ = c; 1244 } 1245 1246 *s++ = '-'; 1247 n = (a->ax25_call[6] >> 1) & 0x0F; 1248 if (n > 9) { 1249 *s++ = '1'; 1250 n -= 10; 1251 } 1252 1253 *s++ = n + '0'; 1254 *s++ = '\0'; 1255 1256 if (*buf == '\0' || *buf == '-') 1257 return "*"; 1258 1259 return buf; 1260 } 1261 #endif /* CONFIG_AX25 */ 1262 1263 #define HBUFFERLEN 30 1264 1265 static void arp_format_neigh_entry(struct seq_file *seq, 1266 struct neighbour *n) 1267 { 1268 char hbuffer[HBUFFERLEN]; 1269 int k, j; 1270 char tbuf[16]; 1271 struct net_device *dev = n->dev; 1272 int hatype = dev->type; 1273 1274 read_lock(&n->lock); 1275 /* Convert hardware address to XX:XX:XX:XX ... form. */ 1276 #if IS_ENABLED(CONFIG_AX25) 1277 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM) 1278 ax2asc2((ax25_address *)n->ha, hbuffer); 1279 else { 1280 #endif 1281 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) { 1282 hbuffer[k++] = hex_asc_hi(n->ha[j]); 1283 hbuffer[k++] = hex_asc_lo(n->ha[j]); 1284 hbuffer[k++] = ':'; 1285 } 1286 if (k != 0) 1287 --k; 1288 hbuffer[k] = 0; 1289 #if IS_ENABLED(CONFIG_AX25) 1290 } 1291 #endif 1292 sprintf(tbuf, "%pI4", n->primary_key); 1293 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n", 1294 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name); 1295 read_unlock(&n->lock); 1296 } 1297 1298 static void arp_format_pneigh_entry(struct seq_file *seq, 1299 struct pneigh_entry *n) 1300 { 1301 struct net_device *dev = n->dev; 1302 int hatype = dev ? dev->type : 0; 1303 char tbuf[16]; 1304 1305 sprintf(tbuf, "%pI4", n->key); 1306 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n", 1307 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00", 1308 dev ? dev->name : "*"); 1309 } 1310 1311 static int arp_seq_show(struct seq_file *seq, void *v) 1312 { 1313 if (v == SEQ_START_TOKEN) { 1314 seq_puts(seq, "IP address HW type Flags " 1315 "HW address Mask Device\n"); 1316 } else { 1317 struct neigh_seq_state *state = seq->private; 1318 1319 if (state->flags & NEIGH_SEQ_IS_PNEIGH) 1320 arp_format_pneigh_entry(seq, v); 1321 else 1322 arp_format_neigh_entry(seq, v); 1323 } 1324 1325 return 0; 1326 } 1327 1328 static void *arp_seq_start(struct seq_file *seq, loff_t *pos) 1329 { 1330 /* Don't want to confuse "arp -a" w/ magic entries, 1331 * so we tell the generic iterator to skip NUD_NOARP. 1332 */ 1333 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP); 1334 } 1335 1336 /* ------------------------------------------------------------------------ */ 1337 1338 static const struct seq_operations arp_seq_ops = { 1339 .start = arp_seq_start, 1340 .next = neigh_seq_next, 1341 .stop = neigh_seq_stop, 1342 .show = arp_seq_show, 1343 }; 1344 1345 static int arp_seq_open(struct inode *inode, struct file *file) 1346 { 1347 return seq_open_net(inode, file, &arp_seq_ops, 1348 sizeof(struct neigh_seq_state)); 1349 } 1350 1351 static const struct file_operations arp_seq_fops = { 1352 .owner = THIS_MODULE, 1353 .open = arp_seq_open, 1354 .read = seq_read, 1355 .llseek = seq_lseek, 1356 .release = seq_release_net, 1357 }; 1358 1359 1360 static int __net_init arp_net_init(struct net *net) 1361 { 1362 if (!proc_create("arp", S_IRUGO, net->proc_net, &arp_seq_fops)) 1363 return -ENOMEM; 1364 return 0; 1365 } 1366 1367 static void __net_exit arp_net_exit(struct net *net) 1368 { 1369 remove_proc_entry("arp", net->proc_net); 1370 } 1371 1372 static struct pernet_operations arp_net_ops = { 1373 .init = arp_net_init, 1374 .exit = arp_net_exit, 1375 }; 1376 1377 static int __init arp_proc_init(void) 1378 { 1379 return register_pernet_subsys(&arp_net_ops); 1380 } 1381 1382 #else /* CONFIG_PROC_FS */ 1383 1384 static int __init arp_proc_init(void) 1385 { 1386 return 0; 1387 } 1388 1389 #endif /* CONFIG_PROC_FS */ 1390