arp.c revision f8126f1d5136be1ca1a3536d43ad7a710b5620f8
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 */ 124static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd); 125static int arp_constructor(struct neighbour *neigh); 126static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb); 127static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb); 128static void parp_redo(struct sk_buff *skb); 129 130static const struct neigh_ops arp_generic_ops = { 131 .family = AF_INET, 132 .solicit = arp_solicit, 133 .error_report = arp_error_report, 134 .output = neigh_resolve_output, 135 .connected_output = neigh_connected_output, 136}; 137 138static const struct neigh_ops arp_hh_ops = { 139 .family = AF_INET, 140 .solicit = arp_solicit, 141 .error_report = arp_error_report, 142 .output = neigh_resolve_output, 143 .connected_output = neigh_resolve_output, 144}; 145 146static const struct neigh_ops arp_direct_ops = { 147 .family = AF_INET, 148 .output = neigh_direct_output, 149 .connected_output = neigh_direct_output, 150}; 151 152static const struct neigh_ops arp_broken_ops = { 153 .family = AF_INET, 154 .solicit = arp_solicit, 155 .error_report = arp_error_report, 156 .output = neigh_compat_output, 157 .connected_output = neigh_compat_output, 158}; 159 160struct neigh_table arp_tbl = { 161 .family = AF_INET, 162 .key_len = 4, 163 .hash = arp_hash, 164 .constructor = arp_constructor, 165 .proxy_redo = parp_redo, 166 .id = "arp_cache", 167 .parms = { 168 .tbl = &arp_tbl, 169 .base_reachable_time = 30 * HZ, 170 .retrans_time = 1 * HZ, 171 .gc_staletime = 60 * HZ, 172 .reachable_time = 30 * HZ, 173 .delay_probe_time = 5 * HZ, 174 .queue_len_bytes = 64*1024, 175 .ucast_probes = 3, 176 .mcast_probes = 3, 177 .anycast_delay = 1 * HZ, 178 .proxy_delay = (8 * HZ) / 10, 179 .proxy_qlen = 64, 180 .locktime = 1 * HZ, 181 }, 182 .gc_interval = 30 * HZ, 183 .gc_thresh1 = 128, 184 .gc_thresh2 = 512, 185 .gc_thresh3 = 1024, 186}; 187EXPORT_SYMBOL(arp_tbl); 188 189int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir) 190{ 191 switch (dev->type) { 192 case ARPHRD_ETHER: 193 case ARPHRD_FDDI: 194 case ARPHRD_IEEE802: 195 ip_eth_mc_map(addr, haddr); 196 return 0; 197 case ARPHRD_INFINIBAND: 198 ip_ib_mc_map(addr, dev->broadcast, haddr); 199 return 0; 200 case ARPHRD_IPGRE: 201 ip_ipgre_mc_map(addr, dev->broadcast, haddr); 202 return 0; 203 default: 204 if (dir) { 205 memcpy(haddr, dev->broadcast, dev->addr_len); 206 return 0; 207 } 208 } 209 return -EINVAL; 210} 211 212 213static u32 arp_hash(const void *pkey, 214 const struct net_device *dev, 215 __u32 *hash_rnd) 216{ 217 return arp_hashfn(*(u32 *)pkey, dev, *hash_rnd); 218} 219 220static int arp_constructor(struct neighbour *neigh) 221{ 222 __be32 addr = *(__be32 *)neigh->primary_key; 223 struct net_device *dev = neigh->dev; 224 struct in_device *in_dev; 225 struct neigh_parms *parms; 226 227 rcu_read_lock(); 228 in_dev = __in_dev_get_rcu(dev); 229 if (in_dev == NULL) { 230 rcu_read_unlock(); 231 return -EINVAL; 232 } 233 234 neigh->type = inet_addr_type(dev_net(dev), addr); 235 236 parms = in_dev->arp_parms; 237 __neigh_parms_put(neigh->parms); 238 neigh->parms = neigh_parms_clone(parms); 239 rcu_read_unlock(); 240 241 if (!dev->header_ops) { 242 neigh->nud_state = NUD_NOARP; 243 neigh->ops = &arp_direct_ops; 244 neigh->output = neigh_direct_output; 245 } else { 246 /* Good devices (checked by reading texts, but only Ethernet is 247 tested) 248 249 ARPHRD_ETHER: (ethernet, apfddi) 250 ARPHRD_FDDI: (fddi) 251 ARPHRD_IEEE802: (tr) 252 ARPHRD_METRICOM: (strip) 253 ARPHRD_ARCNET: 254 etc. etc. etc. 255 256 ARPHRD_IPDDP will also work, if author repairs it. 257 I did not it, because this driver does not work even 258 in old paradigm. 259 */ 260 261#if 1 262 /* So... these "amateur" devices are hopeless. 263 The only thing, that I can say now: 264 It is very sad that we need to keep ugly obsolete 265 code to make them happy. 266 267 They should be moved to more reasonable state, now 268 they use rebuild_header INSTEAD OF hard_start_xmit!!! 269 Besides that, they are sort of out of date 270 (a lot of redundant clones/copies, useless in 2.1), 271 I wonder why people believe that they work. 272 */ 273 switch (dev->type) { 274 default: 275 break; 276 case ARPHRD_ROSE: 277#if IS_ENABLED(CONFIG_AX25) 278 case ARPHRD_AX25: 279#if IS_ENABLED(CONFIG_NETROM) 280 case ARPHRD_NETROM: 281#endif 282 neigh->ops = &arp_broken_ops; 283 neigh->output = neigh->ops->output; 284 return 0; 285#else 286 break; 287#endif 288 } 289#endif 290 if (neigh->type == RTN_MULTICAST) { 291 neigh->nud_state = NUD_NOARP; 292 arp_mc_map(addr, neigh->ha, dev, 1); 293 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) { 294 neigh->nud_state = NUD_NOARP; 295 memcpy(neigh->ha, dev->dev_addr, dev->addr_len); 296 } else if (neigh->type == RTN_BROADCAST || 297 (dev->flags & IFF_POINTOPOINT)) { 298 neigh->nud_state = NUD_NOARP; 299 memcpy(neigh->ha, dev->broadcast, dev->addr_len); 300 } 301 302 if (dev->header_ops->cache) 303 neigh->ops = &arp_hh_ops; 304 else 305 neigh->ops = &arp_generic_ops; 306 307 if (neigh->nud_state & NUD_VALID) 308 neigh->output = neigh->ops->connected_output; 309 else 310 neigh->output = neigh->ops->output; 311 } 312 return 0; 313} 314 315static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb) 316{ 317 dst_link_failure(skb); 318 kfree_skb(skb); 319} 320 321static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb) 322{ 323 __be32 saddr = 0; 324 u8 *dst_ha = NULL; 325 struct net_device *dev = neigh->dev; 326 __be32 target = *(__be32 *)neigh->primary_key; 327 int probes = atomic_read(&neigh->probes); 328 struct in_device *in_dev; 329 330 rcu_read_lock(); 331 in_dev = __in_dev_get_rcu(dev); 332 if (!in_dev) { 333 rcu_read_unlock(); 334 return; 335 } 336 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) { 337 default: 338 case 0: /* By default announce any local IP */ 339 if (skb && inet_addr_type(dev_net(dev), 340 ip_hdr(skb)->saddr) == RTN_LOCAL) 341 saddr = ip_hdr(skb)->saddr; 342 break; 343 case 1: /* Restrict announcements of saddr in same subnet */ 344 if (!skb) 345 break; 346 saddr = ip_hdr(skb)->saddr; 347 if (inet_addr_type(dev_net(dev), saddr) == RTN_LOCAL) { 348 /* saddr should be known to target */ 349 if (inet_addr_onlink(in_dev, target, saddr)) 350 break; 351 } 352 saddr = 0; 353 break; 354 case 2: /* Avoid secondary IPs, get a primary/preferred one */ 355 break; 356 } 357 rcu_read_unlock(); 358 359 if (!saddr) 360 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK); 361 362 probes -= neigh->parms->ucast_probes; 363 if (probes < 0) { 364 if (!(neigh->nud_state & NUD_VALID)) 365 pr_debug("trying to ucast probe in NUD_INVALID\n"); 366 dst_ha = neigh->ha; 367 read_lock_bh(&neigh->lock); 368 } else { 369 probes -= neigh->parms->app_probes; 370 if (probes < 0) { 371#ifdef CONFIG_ARPD 372 neigh_app_ns(neigh); 373#endif 374 return; 375 } 376 } 377 378 arp_send(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr, 379 dst_ha, dev->dev_addr, NULL); 380 if (dst_ha) 381 read_unlock_bh(&neigh->lock); 382} 383 384static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip) 385{ 386 int scope; 387 388 switch (IN_DEV_ARP_IGNORE(in_dev)) { 389 case 0: /* Reply, the tip is already validated */ 390 return 0; 391 case 1: /* Reply only if tip is configured on the incoming interface */ 392 sip = 0; 393 scope = RT_SCOPE_HOST; 394 break; 395 case 2: /* 396 * Reply only if tip is configured on the incoming interface 397 * and is in same subnet as sip 398 */ 399 scope = RT_SCOPE_HOST; 400 break; 401 case 3: /* Do not reply for scope host addresses */ 402 sip = 0; 403 scope = RT_SCOPE_LINK; 404 break; 405 case 4: /* Reserved */ 406 case 5: 407 case 6: 408 case 7: 409 return 0; 410 case 8: /* Do not reply */ 411 return 1; 412 default: 413 return 0; 414 } 415 return !inet_confirm_addr(in_dev, sip, tip, scope); 416} 417 418static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev) 419{ 420 struct rtable *rt; 421 int flag = 0; 422 /*unsigned long now; */ 423 struct net *net = dev_net(dev); 424 425 rt = ip_route_output(net, sip, tip, 0, 0); 426 if (IS_ERR(rt)) 427 return 1; 428 if (rt->dst.dev != dev) { 429 NET_INC_STATS_BH(net, LINUX_MIB_ARPFILTER); 430 flag = 1; 431 } 432 ip_rt_put(rt); 433 return flag; 434} 435 436/* OBSOLETE FUNCTIONS */ 437 438/* 439 * Find an arp mapping in the cache. If not found, post a request. 440 * 441 * It is very UGLY routine: it DOES NOT use skb->dst->neighbour, 442 * even if it exists. It is supposed that skb->dev was mangled 443 * by a virtual device (eql, shaper). Nobody but broken devices 444 * is allowed to use this function, it is scheduled to be removed. --ANK 445 */ 446 447static int arp_set_predefined(int addr_hint, unsigned char *haddr, 448 __be32 paddr, struct net_device *dev) 449{ 450 switch (addr_hint) { 451 case RTN_LOCAL: 452 pr_debug("arp called for own IP address\n"); 453 memcpy(haddr, dev->dev_addr, dev->addr_len); 454 return 1; 455 case RTN_MULTICAST: 456 arp_mc_map(paddr, haddr, dev, 1); 457 return 1; 458 case RTN_BROADCAST: 459 memcpy(haddr, dev->broadcast, dev->addr_len); 460 return 1; 461 } 462 return 0; 463} 464 465 466int arp_find(unsigned char *haddr, struct sk_buff *skb) 467{ 468 struct net_device *dev = skb->dev; 469 __be32 paddr; 470 struct neighbour *n; 471 472 if (!skb_dst(skb)) { 473 pr_debug("arp_find is called with dst==NULL\n"); 474 kfree_skb(skb); 475 return 1; 476 } 477 478 paddr = rt_nexthop(skb_rtable(skb), ip_hdr(skb)->daddr); 479 if (arp_set_predefined(inet_addr_type(dev_net(dev), paddr), haddr, 480 paddr, dev)) 481 return 0; 482 483 n = __neigh_lookup(&arp_tbl, &paddr, dev, 1); 484 485 if (n) { 486 n->used = jiffies; 487 if (n->nud_state & NUD_VALID || neigh_event_send(n, skb) == 0) { 488 neigh_ha_snapshot(haddr, n, dev); 489 neigh_release(n); 490 return 0; 491 } 492 neigh_release(n); 493 } else 494 kfree_skb(skb); 495 return 1; 496} 497EXPORT_SYMBOL(arp_find); 498 499/* END OF OBSOLETE FUNCTIONS */ 500 501/* 502 * Check if we can use proxy ARP for this path 503 */ 504static inline int arp_fwd_proxy(struct in_device *in_dev, 505 struct net_device *dev, struct rtable *rt) 506{ 507 struct in_device *out_dev; 508 int imi, omi = -1; 509 510 if (rt->dst.dev == dev) 511 return 0; 512 513 if (!IN_DEV_PROXY_ARP(in_dev)) 514 return 0; 515 imi = IN_DEV_MEDIUM_ID(in_dev); 516 if (imi == 0) 517 return 1; 518 if (imi == -1) 519 return 0; 520 521 /* place to check for proxy_arp for routes */ 522 523 out_dev = __in_dev_get_rcu(rt->dst.dev); 524 if (out_dev) 525 omi = IN_DEV_MEDIUM_ID(out_dev); 526 527 return omi != imi && omi != -1; 528} 529 530/* 531 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev) 532 * 533 * RFC3069 supports proxy arp replies back to the same interface. This 534 * is done to support (ethernet) switch features, like RFC 3069, where 535 * the individual ports are not allowed to communicate with each 536 * other, BUT they are allowed to talk to the upstream router. As 537 * described in RFC 3069, it is possible to allow these hosts to 538 * communicate through the upstream router, by proxy_arp'ing. 539 * 540 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation" 541 * 542 * This technology is known by different names: 543 * In RFC 3069 it is called VLAN Aggregation. 544 * Cisco and Allied Telesyn call it Private VLAN. 545 * Hewlett-Packard call it Source-Port filtering or port-isolation. 546 * Ericsson call it MAC-Forced Forwarding (RFC Draft). 547 * 548 */ 549static inline int arp_fwd_pvlan(struct in_device *in_dev, 550 struct net_device *dev, struct rtable *rt, 551 __be32 sip, __be32 tip) 552{ 553 /* Private VLAN is only concerned about the same ethernet segment */ 554 if (rt->dst.dev != dev) 555 return 0; 556 557 /* Don't reply on self probes (often done by windowz boxes)*/ 558 if (sip == tip) 559 return 0; 560 561 if (IN_DEV_PROXY_ARP_PVLAN(in_dev)) 562 return 1; 563 else 564 return 0; 565} 566 567/* 568 * Interface to link layer: send routine and receive handler. 569 */ 570 571/* 572 * Create an arp packet. If (dest_hw == NULL), we create a broadcast 573 * message. 574 */ 575struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip, 576 struct net_device *dev, __be32 src_ip, 577 const unsigned char *dest_hw, 578 const unsigned char *src_hw, 579 const unsigned char *target_hw) 580{ 581 struct sk_buff *skb; 582 struct arphdr *arp; 583 unsigned char *arp_ptr; 584 int hlen = LL_RESERVED_SPACE(dev); 585 int tlen = dev->needed_tailroom; 586 587 /* 588 * Allocate a buffer 589 */ 590 591 skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC); 592 if (skb == NULL) 593 return NULL; 594 595 skb_reserve(skb, hlen); 596 skb_reset_network_header(skb); 597 arp = (struct arphdr *) skb_put(skb, arp_hdr_len(dev)); 598 skb->dev = dev; 599 skb->protocol = htons(ETH_P_ARP); 600 if (src_hw == NULL) 601 src_hw = dev->dev_addr; 602 if (dest_hw == NULL) 603 dest_hw = dev->broadcast; 604 605 /* 606 * Fill the device header for the ARP frame 607 */ 608 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0) 609 goto out; 610 611 /* 612 * Fill out the arp protocol part. 613 * 614 * The arp hardware type should match the device type, except for FDDI, 615 * which (according to RFC 1390) should always equal 1 (Ethernet). 616 */ 617 /* 618 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the 619 * DIX code for the protocol. Make these device structure fields. 620 */ 621 switch (dev->type) { 622 default: 623 arp->ar_hrd = htons(dev->type); 624 arp->ar_pro = htons(ETH_P_IP); 625 break; 626 627#if IS_ENABLED(CONFIG_AX25) 628 case ARPHRD_AX25: 629 arp->ar_hrd = htons(ARPHRD_AX25); 630 arp->ar_pro = htons(AX25_P_IP); 631 break; 632 633#if IS_ENABLED(CONFIG_NETROM) 634 case ARPHRD_NETROM: 635 arp->ar_hrd = htons(ARPHRD_NETROM); 636 arp->ar_pro = htons(AX25_P_IP); 637 break; 638#endif 639#endif 640 641#if IS_ENABLED(CONFIG_FDDI) 642 case ARPHRD_FDDI: 643 arp->ar_hrd = htons(ARPHRD_ETHER); 644 arp->ar_pro = htons(ETH_P_IP); 645 break; 646#endif 647 } 648 649 arp->ar_hln = dev->addr_len; 650 arp->ar_pln = 4; 651 arp->ar_op = htons(type); 652 653 arp_ptr = (unsigned char *)(arp + 1); 654 655 memcpy(arp_ptr, src_hw, dev->addr_len); 656 arp_ptr += dev->addr_len; 657 memcpy(arp_ptr, &src_ip, 4); 658 arp_ptr += 4; 659 if (target_hw != NULL) 660 memcpy(arp_ptr, target_hw, dev->addr_len); 661 else 662 memset(arp_ptr, 0, dev->addr_len); 663 arp_ptr += dev->addr_len; 664 memcpy(arp_ptr, &dest_ip, 4); 665 666 return skb; 667 668out: 669 kfree_skb(skb); 670 return NULL; 671} 672EXPORT_SYMBOL(arp_create); 673 674/* 675 * Send an arp packet. 676 */ 677void arp_xmit(struct sk_buff *skb) 678{ 679 /* Send it off, maybe filter it using firewalling first. */ 680 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, skb, NULL, skb->dev, dev_queue_xmit); 681} 682EXPORT_SYMBOL(arp_xmit); 683 684/* 685 * Create and send an arp packet. 686 */ 687void arp_send(int type, int ptype, __be32 dest_ip, 688 struct net_device *dev, __be32 src_ip, 689 const unsigned char *dest_hw, const unsigned char *src_hw, 690 const unsigned char *target_hw) 691{ 692 struct sk_buff *skb; 693 694 /* 695 * No arp on this interface. 696 */ 697 698 if (dev->flags&IFF_NOARP) 699 return; 700 701 skb = arp_create(type, ptype, dest_ip, dev, src_ip, 702 dest_hw, src_hw, target_hw); 703 if (skb == NULL) 704 return; 705 706 arp_xmit(skb); 707} 708EXPORT_SYMBOL(arp_send); 709 710/* 711 * Process an arp request. 712 */ 713 714static int arp_process(struct sk_buff *skb) 715{ 716 struct net_device *dev = skb->dev; 717 struct in_device *in_dev = __in_dev_get_rcu(dev); 718 struct arphdr *arp; 719 unsigned char *arp_ptr; 720 struct rtable *rt; 721 unsigned char *sha; 722 __be32 sip, tip; 723 u16 dev_type = dev->type; 724 int addr_type; 725 struct neighbour *n; 726 struct net *net = dev_net(dev); 727 728 /* arp_rcv below verifies the ARP header and verifies the device 729 * is ARP'able. 730 */ 731 732 if (in_dev == NULL) 733 goto out; 734 735 arp = arp_hdr(skb); 736 737 switch (dev_type) { 738 default: 739 if (arp->ar_pro != htons(ETH_P_IP) || 740 htons(dev_type) != arp->ar_hrd) 741 goto out; 742 break; 743 case ARPHRD_ETHER: 744 case ARPHRD_FDDI: 745 case ARPHRD_IEEE802: 746 /* 747 * ETHERNET, and Fibre Channel (which are IEEE 802 748 * devices, according to RFC 2625) devices will accept ARP 749 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2). 750 * This is the case also of FDDI, where the RFC 1390 says that 751 * FDDI devices should accept ARP hardware of (1) Ethernet, 752 * however, to be more robust, we'll accept both 1 (Ethernet) 753 * or 6 (IEEE 802.2) 754 */ 755 if ((arp->ar_hrd != htons(ARPHRD_ETHER) && 756 arp->ar_hrd != htons(ARPHRD_IEEE802)) || 757 arp->ar_pro != htons(ETH_P_IP)) 758 goto out; 759 break; 760 case ARPHRD_AX25: 761 if (arp->ar_pro != htons(AX25_P_IP) || 762 arp->ar_hrd != htons(ARPHRD_AX25)) 763 goto out; 764 break; 765 case ARPHRD_NETROM: 766 if (arp->ar_pro != htons(AX25_P_IP) || 767 arp->ar_hrd != htons(ARPHRD_NETROM)) 768 goto out; 769 break; 770 } 771 772 /* Understand only these message types */ 773 774 if (arp->ar_op != htons(ARPOP_REPLY) && 775 arp->ar_op != htons(ARPOP_REQUEST)) 776 goto out; 777 778/* 779 * Extract fields 780 */ 781 arp_ptr = (unsigned char *)(arp + 1); 782 sha = arp_ptr; 783 arp_ptr += dev->addr_len; 784 memcpy(&sip, arp_ptr, 4); 785 arp_ptr += 4; 786 arp_ptr += dev->addr_len; 787 memcpy(&tip, arp_ptr, 4); 788/* 789 * Check for bad requests for 127.x.x.x and requests for multicast 790 * addresses. If this is one such, delete it. 791 */ 792 if (ipv4_is_multicast(tip) || 793 (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip))) 794 goto out; 795 796/* 797 * Special case: We must set Frame Relay source Q.922 address 798 */ 799 if (dev_type == ARPHRD_DLCI) 800 sha = dev->broadcast; 801 802/* 803 * Process entry. The idea here is we want to send a reply if it is a 804 * request for us or if it is a request for someone else that we hold 805 * a proxy for. We want to add an entry to our cache if it is a reply 806 * to us or if it is a request for our address. 807 * (The assumption for this last is that if someone is requesting our 808 * address, they are probably intending to talk to us, so it saves time 809 * if we cache their address. Their address is also probably not in 810 * our cache, since ours is not in their cache.) 811 * 812 * Putting this another way, we only care about replies if they are to 813 * us, in which case we add them to the cache. For requests, we care 814 * about those for us and those for our proxies. We reply to both, 815 * and in the case of requests for us we add the requester to the arp 816 * cache. 817 */ 818 819 /* Special case: IPv4 duplicate address detection packet (RFC2131) */ 820 if (sip == 0) { 821 if (arp->ar_op == htons(ARPOP_REQUEST) && 822 inet_addr_type(net, tip) == RTN_LOCAL && 823 !arp_ignore(in_dev, sip, tip)) 824 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, sha, 825 dev->dev_addr, sha); 826 goto out; 827 } 828 829 if (arp->ar_op == htons(ARPOP_REQUEST) && 830 ip_route_input(skb, tip, sip, 0, dev) == 0) { 831 832 rt = skb_rtable(skb); 833 addr_type = rt->rt_type; 834 835 if (addr_type == RTN_LOCAL) { 836 int dont_send; 837 838 dont_send = arp_ignore(in_dev, sip, tip); 839 if (!dont_send && IN_DEV_ARPFILTER(in_dev)) 840 dont_send = arp_filter(sip, tip, dev); 841 if (!dont_send) { 842 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 843 if (n) { 844 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, 845 dev, tip, sha, dev->dev_addr, 846 sha); 847 neigh_release(n); 848 } 849 } 850 goto out; 851 } else if (IN_DEV_FORWARD(in_dev)) { 852 if (addr_type == RTN_UNICAST && 853 (arp_fwd_proxy(in_dev, dev, rt) || 854 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) || 855 (rt->dst.dev != dev && 856 pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) { 857 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 858 if (n) 859 neigh_release(n); 860 861 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED || 862 skb->pkt_type == PACKET_HOST || 863 in_dev->arp_parms->proxy_delay == 0) { 864 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, 865 dev, tip, sha, dev->dev_addr, 866 sha); 867 } else { 868 pneigh_enqueue(&arp_tbl, 869 in_dev->arp_parms, skb); 870 return 0; 871 } 872 goto out; 873 } 874 } 875 } 876 877 /* Update our ARP tables */ 878 879 n = __neigh_lookup(&arp_tbl, &sip, dev, 0); 880 881 if (IN_DEV_ARP_ACCEPT(in_dev)) { 882 /* Unsolicited ARP is not accepted by default. 883 It is possible, that this option should be enabled for some 884 devices (strip is candidate) 885 */ 886 if (n == NULL && 887 (arp->ar_op == htons(ARPOP_REPLY) || 888 (arp->ar_op == htons(ARPOP_REQUEST) && tip == sip)) && 889 inet_addr_type(net, sip) == RTN_UNICAST) 890 n = __neigh_lookup(&arp_tbl, &sip, dev, 1); 891 } 892 893 if (n) { 894 int state = NUD_REACHABLE; 895 int override; 896 897 /* If several different ARP replies follows back-to-back, 898 use the FIRST one. It is possible, if several proxy 899 agents are active. Taking the first reply prevents 900 arp trashing and chooses the fastest router. 901 */ 902 override = time_after(jiffies, n->updated + n->parms->locktime); 903 904 /* Broadcast replies and request packets 905 do not assert neighbour reachability. 906 */ 907 if (arp->ar_op != htons(ARPOP_REPLY) || 908 skb->pkt_type != PACKET_HOST) 909 state = NUD_STALE; 910 neigh_update(n, sha, state, 911 override ? NEIGH_UPDATE_F_OVERRIDE : 0); 912 neigh_release(n); 913 } 914 915out: 916 consume_skb(skb); 917 return 0; 918} 919 920static void parp_redo(struct sk_buff *skb) 921{ 922 arp_process(skb); 923} 924 925 926/* 927 * Receive an arp request from the device layer. 928 */ 929 930static int arp_rcv(struct sk_buff *skb, struct net_device *dev, 931 struct packet_type *pt, struct net_device *orig_dev) 932{ 933 struct arphdr *arp; 934 935 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */ 936 if (!pskb_may_pull(skb, arp_hdr_len(dev))) 937 goto freeskb; 938 939 arp = arp_hdr(skb); 940 if (arp->ar_hln != dev->addr_len || 941 dev->flags & IFF_NOARP || 942 skb->pkt_type == PACKET_OTHERHOST || 943 skb->pkt_type == PACKET_LOOPBACK || 944 arp->ar_pln != 4) 945 goto freeskb; 946 947 skb = skb_share_check(skb, GFP_ATOMIC); 948 if (skb == NULL) 949 goto out_of_mem; 950 951 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb)); 952 953 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, skb, dev, NULL, arp_process); 954 955freeskb: 956 kfree_skb(skb); 957out_of_mem: 958 return 0; 959} 960 961/* 962 * User level interface (ioctl) 963 */ 964 965/* 966 * Set (create) an ARP cache entry. 967 */ 968 969static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on) 970{ 971 if (dev == NULL) { 972 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on; 973 return 0; 974 } 975 if (__in_dev_get_rtnl(dev)) { 976 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on); 977 return 0; 978 } 979 return -ENXIO; 980} 981 982static int arp_req_set_public(struct net *net, struct arpreq *r, 983 struct net_device *dev) 984{ 985 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 986 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 987 988 if (mask && mask != htonl(0xFFFFFFFF)) 989 return -EINVAL; 990 if (!dev && (r->arp_flags & ATF_COM)) { 991 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family, 992 r->arp_ha.sa_data); 993 if (!dev) 994 return -ENODEV; 995 } 996 if (mask) { 997 if (pneigh_lookup(&arp_tbl, net, &ip, dev, 1) == NULL) 998 return -ENOBUFS; 999 return 0; 1000 } 1001 1002 return arp_req_set_proxy(net, dev, 1); 1003} 1004 1005static int arp_req_set(struct net *net, struct arpreq *r, 1006 struct net_device *dev) 1007{ 1008 __be32 ip; 1009 struct neighbour *neigh; 1010 int err; 1011 1012 if (r->arp_flags & ATF_PUBL) 1013 return arp_req_set_public(net, r, dev); 1014 1015 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1016 if (r->arp_flags & ATF_PERM) 1017 r->arp_flags |= ATF_COM; 1018 if (dev == NULL) { 1019 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0); 1020 1021 if (IS_ERR(rt)) 1022 return PTR_ERR(rt); 1023 dev = rt->dst.dev; 1024 ip_rt_put(rt); 1025 if (!dev) 1026 return -EINVAL; 1027 } 1028 switch (dev->type) { 1029#if IS_ENABLED(CONFIG_FDDI) 1030 case ARPHRD_FDDI: 1031 /* 1032 * According to RFC 1390, FDDI devices should accept ARP 1033 * hardware types of 1 (Ethernet). However, to be more 1034 * robust, we'll accept hardware types of either 1 (Ethernet) 1035 * or 6 (IEEE 802.2). 1036 */ 1037 if (r->arp_ha.sa_family != ARPHRD_FDDI && 1038 r->arp_ha.sa_family != ARPHRD_ETHER && 1039 r->arp_ha.sa_family != ARPHRD_IEEE802) 1040 return -EINVAL; 1041 break; 1042#endif 1043 default: 1044 if (r->arp_ha.sa_family != dev->type) 1045 return -EINVAL; 1046 break; 1047 } 1048 1049 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev); 1050 err = PTR_ERR(neigh); 1051 if (!IS_ERR(neigh)) { 1052 unsigned int state = NUD_STALE; 1053 if (r->arp_flags & ATF_PERM) 1054 state = NUD_PERMANENT; 1055 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ? 1056 r->arp_ha.sa_data : NULL, state, 1057 NEIGH_UPDATE_F_OVERRIDE | 1058 NEIGH_UPDATE_F_ADMIN); 1059 neigh_release(neigh); 1060 } 1061 return err; 1062} 1063 1064static unsigned int arp_state_to_flags(struct neighbour *neigh) 1065{ 1066 if (neigh->nud_state&NUD_PERMANENT) 1067 return ATF_PERM | ATF_COM; 1068 else if (neigh->nud_state&NUD_VALID) 1069 return ATF_COM; 1070 else 1071 return 0; 1072} 1073 1074/* 1075 * Get an ARP cache entry. 1076 */ 1077 1078static int arp_req_get(struct arpreq *r, struct net_device *dev) 1079{ 1080 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; 1081 struct neighbour *neigh; 1082 int err = -ENXIO; 1083 1084 neigh = neigh_lookup(&arp_tbl, &ip, dev); 1085 if (neigh) { 1086 read_lock_bh(&neigh->lock); 1087 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len); 1088 r->arp_flags = arp_state_to_flags(neigh); 1089 read_unlock_bh(&neigh->lock); 1090 r->arp_ha.sa_family = dev->type; 1091 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev)); 1092 neigh_release(neigh); 1093 err = 0; 1094 } 1095 return err; 1096} 1097 1098int arp_invalidate(struct net_device *dev, __be32 ip) 1099{ 1100 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev); 1101 int err = -ENXIO; 1102 1103 if (neigh) { 1104 if (neigh->nud_state & ~NUD_NOARP) 1105 err = neigh_update(neigh, NULL, NUD_FAILED, 1106 NEIGH_UPDATE_F_OVERRIDE| 1107 NEIGH_UPDATE_F_ADMIN); 1108 neigh_release(neigh); 1109 } 1110 1111 return err; 1112} 1113EXPORT_SYMBOL(arp_invalidate); 1114 1115static int arp_req_delete_public(struct net *net, struct arpreq *r, 1116 struct net_device *dev) 1117{ 1118 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; 1119 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 1120 1121 if (mask == htonl(0xFFFFFFFF)) 1122 return pneigh_delete(&arp_tbl, net, &ip, dev); 1123 1124 if (mask) 1125 return -EINVAL; 1126 1127 return arp_req_set_proxy(net, dev, 0); 1128} 1129 1130static int arp_req_delete(struct net *net, struct arpreq *r, 1131 struct net_device *dev) 1132{ 1133 __be32 ip; 1134 1135 if (r->arp_flags & ATF_PUBL) 1136 return arp_req_delete_public(net, r, dev); 1137 1138 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1139 if (dev == NULL) { 1140 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0); 1141 if (IS_ERR(rt)) 1142 return PTR_ERR(rt); 1143 dev = rt->dst.dev; 1144 ip_rt_put(rt); 1145 if (!dev) 1146 return -EINVAL; 1147 } 1148 return arp_invalidate(dev, ip); 1149} 1150 1151/* 1152 * Handle an ARP layer I/O control request. 1153 */ 1154 1155int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg) 1156{ 1157 int err; 1158 struct arpreq r; 1159 struct net_device *dev = NULL; 1160 1161 switch (cmd) { 1162 case SIOCDARP: 1163 case SIOCSARP: 1164 if (!capable(CAP_NET_ADMIN)) 1165 return -EPERM; 1166 case SIOCGARP: 1167 err = copy_from_user(&r, arg, sizeof(struct arpreq)); 1168 if (err) 1169 return -EFAULT; 1170 break; 1171 default: 1172 return -EINVAL; 1173 } 1174 1175 if (r.arp_pa.sa_family != AF_INET) 1176 return -EPFNOSUPPORT; 1177 1178 if (!(r.arp_flags & ATF_PUBL) && 1179 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB))) 1180 return -EINVAL; 1181 if (!(r.arp_flags & ATF_NETMASK)) 1182 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr = 1183 htonl(0xFFFFFFFFUL); 1184 rtnl_lock(); 1185 if (r.arp_dev[0]) { 1186 err = -ENODEV; 1187 dev = __dev_get_by_name(net, r.arp_dev); 1188 if (dev == NULL) 1189 goto out; 1190 1191 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */ 1192 if (!r.arp_ha.sa_family) 1193 r.arp_ha.sa_family = dev->type; 1194 err = -EINVAL; 1195 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type) 1196 goto out; 1197 } else if (cmd == SIOCGARP) { 1198 err = -ENODEV; 1199 goto out; 1200 } 1201 1202 switch (cmd) { 1203 case SIOCDARP: 1204 err = arp_req_delete(net, &r, dev); 1205 break; 1206 case SIOCSARP: 1207 err = arp_req_set(net, &r, dev); 1208 break; 1209 case SIOCGARP: 1210 err = arp_req_get(&r, dev); 1211 break; 1212 } 1213out: 1214 rtnl_unlock(); 1215 if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r))) 1216 err = -EFAULT; 1217 return err; 1218} 1219 1220static int arp_netdev_event(struct notifier_block *this, unsigned long event, 1221 void *ptr) 1222{ 1223 struct net_device *dev = ptr; 1224 1225 switch (event) { 1226 case NETDEV_CHANGEADDR: 1227 neigh_changeaddr(&arp_tbl, dev); 1228 rt_cache_flush(dev_net(dev), 0); 1229 break; 1230 default: 1231 break; 1232 } 1233 1234 return NOTIFY_DONE; 1235} 1236 1237static struct notifier_block arp_netdev_notifier = { 1238 .notifier_call = arp_netdev_event, 1239}; 1240 1241/* Note, that it is not on notifier chain. 1242 It is necessary, that this routine was called after route cache will be 1243 flushed. 1244 */ 1245void arp_ifdown(struct net_device *dev) 1246{ 1247 neigh_ifdown(&arp_tbl, dev); 1248} 1249 1250 1251/* 1252 * Called once on startup. 1253 */ 1254 1255static struct packet_type arp_packet_type __read_mostly = { 1256 .type = cpu_to_be16(ETH_P_ARP), 1257 .func = arp_rcv, 1258}; 1259 1260static int arp_proc_init(void); 1261 1262void __init arp_init(void) 1263{ 1264 neigh_table_init(&arp_tbl); 1265 1266 dev_add_pack(&arp_packet_type); 1267 arp_proc_init(); 1268#ifdef CONFIG_SYSCTL 1269 neigh_sysctl_register(NULL, &arp_tbl.parms, "ipv4", NULL); 1270#endif 1271 register_netdevice_notifier(&arp_netdev_notifier); 1272} 1273 1274#ifdef CONFIG_PROC_FS 1275#if IS_ENABLED(CONFIG_AX25) 1276 1277/* ------------------------------------------------------------------------ */ 1278/* 1279 * ax25 -> ASCII conversion 1280 */ 1281static char *ax2asc2(ax25_address *a, char *buf) 1282{ 1283 char c, *s; 1284 int n; 1285 1286 for (n = 0, s = buf; n < 6; n++) { 1287 c = (a->ax25_call[n] >> 1) & 0x7F; 1288 1289 if (c != ' ') 1290 *s++ = c; 1291 } 1292 1293 *s++ = '-'; 1294 n = (a->ax25_call[6] >> 1) & 0x0F; 1295 if (n > 9) { 1296 *s++ = '1'; 1297 n -= 10; 1298 } 1299 1300 *s++ = n + '0'; 1301 *s++ = '\0'; 1302 1303 if (*buf == '\0' || *buf == '-') 1304 return "*"; 1305 1306 return buf; 1307} 1308#endif /* CONFIG_AX25 */ 1309 1310#define HBUFFERLEN 30 1311 1312static void arp_format_neigh_entry(struct seq_file *seq, 1313 struct neighbour *n) 1314{ 1315 char hbuffer[HBUFFERLEN]; 1316 int k, j; 1317 char tbuf[16]; 1318 struct net_device *dev = n->dev; 1319 int hatype = dev->type; 1320 1321 read_lock(&n->lock); 1322 /* Convert hardware address to XX:XX:XX:XX ... form. */ 1323#if IS_ENABLED(CONFIG_AX25) 1324 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM) 1325 ax2asc2((ax25_address *)n->ha, hbuffer); 1326 else { 1327#endif 1328 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) { 1329 hbuffer[k++] = hex_asc_hi(n->ha[j]); 1330 hbuffer[k++] = hex_asc_lo(n->ha[j]); 1331 hbuffer[k++] = ':'; 1332 } 1333 if (k != 0) 1334 --k; 1335 hbuffer[k] = 0; 1336#if IS_ENABLED(CONFIG_AX25) 1337 } 1338#endif 1339 sprintf(tbuf, "%pI4", n->primary_key); 1340 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n", 1341 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name); 1342 read_unlock(&n->lock); 1343} 1344 1345static void arp_format_pneigh_entry(struct seq_file *seq, 1346 struct pneigh_entry *n) 1347{ 1348 struct net_device *dev = n->dev; 1349 int hatype = dev ? dev->type : 0; 1350 char tbuf[16]; 1351 1352 sprintf(tbuf, "%pI4", n->key); 1353 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n", 1354 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00", 1355 dev ? dev->name : "*"); 1356} 1357 1358static int arp_seq_show(struct seq_file *seq, void *v) 1359{ 1360 if (v == SEQ_START_TOKEN) { 1361 seq_puts(seq, "IP address HW type Flags " 1362 "HW address Mask Device\n"); 1363 } else { 1364 struct neigh_seq_state *state = seq->private; 1365 1366 if (state->flags & NEIGH_SEQ_IS_PNEIGH) 1367 arp_format_pneigh_entry(seq, v); 1368 else 1369 arp_format_neigh_entry(seq, v); 1370 } 1371 1372 return 0; 1373} 1374 1375static void *arp_seq_start(struct seq_file *seq, loff_t *pos) 1376{ 1377 /* Don't want to confuse "arp -a" w/ magic entries, 1378 * so we tell the generic iterator to skip NUD_NOARP. 1379 */ 1380 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP); 1381} 1382 1383/* ------------------------------------------------------------------------ */ 1384 1385static const struct seq_operations arp_seq_ops = { 1386 .start = arp_seq_start, 1387 .next = neigh_seq_next, 1388 .stop = neigh_seq_stop, 1389 .show = arp_seq_show, 1390}; 1391 1392static int arp_seq_open(struct inode *inode, struct file *file) 1393{ 1394 return seq_open_net(inode, file, &arp_seq_ops, 1395 sizeof(struct neigh_seq_state)); 1396} 1397 1398static const struct file_operations arp_seq_fops = { 1399 .owner = THIS_MODULE, 1400 .open = arp_seq_open, 1401 .read = seq_read, 1402 .llseek = seq_lseek, 1403 .release = seq_release_net, 1404}; 1405 1406 1407static int __net_init arp_net_init(struct net *net) 1408{ 1409 if (!proc_net_fops_create(net, "arp", S_IRUGO, &arp_seq_fops)) 1410 return -ENOMEM; 1411 return 0; 1412} 1413 1414static void __net_exit arp_net_exit(struct net *net) 1415{ 1416 proc_net_remove(net, "arp"); 1417} 1418 1419static struct pernet_operations arp_net_ops = { 1420 .init = arp_net_init, 1421 .exit = arp_net_exit, 1422}; 1423 1424static int __init arp_proc_init(void) 1425{ 1426 return register_pernet_subsys(&arp_net_ops); 1427} 1428 1429#else /* CONFIG_PROC_FS */ 1430 1431static int __init arp_proc_init(void) 1432{ 1433 return 0; 1434} 1435 1436#endif /* CONFIG_PROC_FS */ 1437