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 static int arp_xmit_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 625 { 626 return dev_queue_xmit(skb); 627 } 628 629 /* 630 * Send an arp packet. 631 */ 632 void arp_xmit(struct sk_buff *skb) 633 { 634 /* Send it off, maybe filter it using firewalling first. */ 635 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, 636 dev_net(skb->dev), NULL, skb, NULL, skb->dev, 637 arp_xmit_finish); 638 } 639 EXPORT_SYMBOL(arp_xmit); 640 641 /* 642 * Process an arp request. 643 */ 644 645 static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb) 646 { 647 struct net_device *dev = skb->dev; 648 struct in_device *in_dev = __in_dev_get_rcu(dev); 649 struct arphdr *arp; 650 unsigned char *arp_ptr; 651 struct rtable *rt; 652 unsigned char *sha; 653 __be32 sip, tip; 654 u16 dev_type = dev->type; 655 int addr_type; 656 struct neighbour *n; 657 bool is_garp = false; 658 659 /* arp_rcv below verifies the ARP header and verifies the device 660 * is ARP'able. 661 */ 662 663 if (!in_dev) 664 goto out; 665 666 arp = arp_hdr(skb); 667 668 switch (dev_type) { 669 default: 670 if (arp->ar_pro != htons(ETH_P_IP) || 671 htons(dev_type) != arp->ar_hrd) 672 goto out; 673 break; 674 case ARPHRD_ETHER: 675 case ARPHRD_FDDI: 676 case ARPHRD_IEEE802: 677 /* 678 * ETHERNET, and Fibre Channel (which are IEEE 802 679 * devices, according to RFC 2625) devices will accept ARP 680 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2). 681 * This is the case also of FDDI, where the RFC 1390 says that 682 * FDDI devices should accept ARP hardware of (1) Ethernet, 683 * however, to be more robust, we'll accept both 1 (Ethernet) 684 * or 6 (IEEE 802.2) 685 */ 686 if ((arp->ar_hrd != htons(ARPHRD_ETHER) && 687 arp->ar_hrd != htons(ARPHRD_IEEE802)) || 688 arp->ar_pro != htons(ETH_P_IP)) 689 goto out; 690 break; 691 case ARPHRD_AX25: 692 if (arp->ar_pro != htons(AX25_P_IP) || 693 arp->ar_hrd != htons(ARPHRD_AX25)) 694 goto out; 695 break; 696 case ARPHRD_NETROM: 697 if (arp->ar_pro != htons(AX25_P_IP) || 698 arp->ar_hrd != htons(ARPHRD_NETROM)) 699 goto out; 700 break; 701 } 702 703 /* Understand only these message types */ 704 705 if (arp->ar_op != htons(ARPOP_REPLY) && 706 arp->ar_op != htons(ARPOP_REQUEST)) 707 goto out; 708 709 /* 710 * Extract fields 711 */ 712 arp_ptr = (unsigned char *)(arp + 1); 713 sha = arp_ptr; 714 arp_ptr += dev->addr_len; 715 memcpy(&sip, arp_ptr, 4); 716 arp_ptr += 4; 717 switch (dev_type) { 718 #if IS_ENABLED(CONFIG_FIREWIRE_NET) 719 case ARPHRD_IEEE1394: 720 break; 721 #endif 722 default: 723 arp_ptr += dev->addr_len; 724 } 725 memcpy(&tip, arp_ptr, 4); 726 /* 727 * Check for bad requests for 127.x.x.x and requests for multicast 728 * addresses. If this is one such, delete it. 729 */ 730 if (ipv4_is_multicast(tip) || 731 (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip))) 732 goto out; 733 734 /* 735 * Special case: We must set Frame Relay source Q.922 address 736 */ 737 if (dev_type == ARPHRD_DLCI) 738 sha = dev->broadcast; 739 740 /* 741 * Process entry. The idea here is we want to send a reply if it is a 742 * request for us or if it is a request for someone else that we hold 743 * a proxy for. We want to add an entry to our cache if it is a reply 744 * to us or if it is a request for our address. 745 * (The assumption for this last is that if someone is requesting our 746 * address, they are probably intending to talk to us, so it saves time 747 * if we cache their address. Their address is also probably not in 748 * our cache, since ours is not in their cache.) 749 * 750 * Putting this another way, we only care about replies if they are to 751 * us, in which case we add them to the cache. For requests, we care 752 * about those for us and those for our proxies. We reply to both, 753 * and in the case of requests for us we add the requester to the arp 754 * cache. 755 */ 756 757 /* Special case: IPv4 duplicate address detection packet (RFC2131) */ 758 if (sip == 0) { 759 if (arp->ar_op == htons(ARPOP_REQUEST) && 760 inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL && 761 !arp_ignore(in_dev, sip, tip)) 762 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, sha, 763 dev->dev_addr, sha); 764 goto out; 765 } 766 767 if (arp->ar_op == htons(ARPOP_REQUEST) && 768 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) { 769 770 rt = skb_rtable(skb); 771 addr_type = rt->rt_type; 772 773 if (addr_type == RTN_LOCAL) { 774 int dont_send; 775 776 dont_send = arp_ignore(in_dev, sip, tip); 777 if (!dont_send && IN_DEV_ARPFILTER(in_dev)) 778 dont_send = arp_filter(sip, tip, dev); 779 if (!dont_send) { 780 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 781 if (n) { 782 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, 783 dev, tip, sha, dev->dev_addr, 784 sha); 785 neigh_release(n); 786 } 787 } 788 goto out; 789 } else if (IN_DEV_FORWARD(in_dev)) { 790 if (addr_type == RTN_UNICAST && 791 (arp_fwd_proxy(in_dev, dev, rt) || 792 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) || 793 (rt->dst.dev != dev && 794 pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) { 795 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 796 if (n) 797 neigh_release(n); 798 799 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED || 800 skb->pkt_type == PACKET_HOST || 801 NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) { 802 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, 803 dev, tip, sha, dev->dev_addr, 804 sha); 805 } else { 806 pneigh_enqueue(&arp_tbl, 807 in_dev->arp_parms, skb); 808 return 0; 809 } 810 goto out; 811 } 812 } 813 } 814 815 /* Update our ARP tables */ 816 817 n = __neigh_lookup(&arp_tbl, &sip, dev, 0); 818 819 if (IN_DEV_ARP_ACCEPT(in_dev)) { 820 unsigned int addr_type = inet_addr_type_dev_table(net, dev, sip); 821 822 /* Unsolicited ARP is not accepted by default. 823 It is possible, that this option should be enabled for some 824 devices (strip is candidate) 825 */ 826 is_garp = arp->ar_op == htons(ARPOP_REQUEST) && tip == sip && 827 addr_type == RTN_UNICAST; 828 829 if (!n && 830 ((arp->ar_op == htons(ARPOP_REPLY) && 831 addr_type == RTN_UNICAST) || is_garp)) 832 n = __neigh_lookup(&arp_tbl, &sip, dev, 1); 833 } 834 835 if (n) { 836 int state = NUD_REACHABLE; 837 int override; 838 839 /* If several different ARP replies follows back-to-back, 840 use the FIRST one. It is possible, if several proxy 841 agents are active. Taking the first reply prevents 842 arp trashing and chooses the fastest router. 843 */ 844 override = time_after(jiffies, 845 n->updated + 846 NEIGH_VAR(n->parms, LOCKTIME)) || 847 is_garp; 848 849 /* Broadcast replies and request packets 850 do not assert neighbour reachability. 851 */ 852 if (arp->ar_op != htons(ARPOP_REPLY) || 853 skb->pkt_type != PACKET_HOST) 854 state = NUD_STALE; 855 neigh_update(n, sha, state, 856 override ? NEIGH_UPDATE_F_OVERRIDE : 0); 857 neigh_release(n); 858 } 859 860 out: 861 consume_skb(skb); 862 return 0; 863 } 864 865 static void parp_redo(struct sk_buff *skb) 866 { 867 arp_process(dev_net(skb->dev), NULL, skb); 868 } 869 870 871 /* 872 * Receive an arp request from the device layer. 873 */ 874 875 static int arp_rcv(struct sk_buff *skb, struct net_device *dev, 876 struct packet_type *pt, struct net_device *orig_dev) 877 { 878 const struct arphdr *arp; 879 880 /* do not tweak dropwatch on an ARP we will ignore */ 881 if (dev->flags & IFF_NOARP || 882 skb->pkt_type == PACKET_OTHERHOST || 883 skb->pkt_type == PACKET_LOOPBACK) 884 goto consumeskb; 885 886 skb = skb_share_check(skb, GFP_ATOMIC); 887 if (!skb) 888 goto out_of_mem; 889 890 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */ 891 if (!pskb_may_pull(skb, arp_hdr_len(dev))) 892 goto freeskb; 893 894 arp = arp_hdr(skb); 895 if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4) 896 goto freeskb; 897 898 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb)); 899 900 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, 901 dev_net(dev), NULL, skb, dev, NULL, 902 arp_process); 903 904 consumeskb: 905 consume_skb(skb); 906 return 0; 907 freeskb: 908 kfree_skb(skb); 909 out_of_mem: 910 return 0; 911 } 912 913 /* 914 * User level interface (ioctl) 915 */ 916 917 /* 918 * Set (create) an ARP cache entry. 919 */ 920 921 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on) 922 { 923 if (!dev) { 924 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on; 925 return 0; 926 } 927 if (__in_dev_get_rtnl(dev)) { 928 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on); 929 return 0; 930 } 931 return -ENXIO; 932 } 933 934 static int arp_req_set_public(struct net *net, struct arpreq *r, 935 struct net_device *dev) 936 { 937 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 938 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 939 940 if (mask && mask != htonl(0xFFFFFFFF)) 941 return -EINVAL; 942 if (!dev && (r->arp_flags & ATF_COM)) { 943 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family, 944 r->arp_ha.sa_data); 945 if (!dev) 946 return -ENODEV; 947 } 948 if (mask) { 949 if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1)) 950 return -ENOBUFS; 951 return 0; 952 } 953 954 return arp_req_set_proxy(net, dev, 1); 955 } 956 957 static int arp_req_set(struct net *net, struct arpreq *r, 958 struct net_device *dev) 959 { 960 __be32 ip; 961 struct neighbour *neigh; 962 int err; 963 964 if (r->arp_flags & ATF_PUBL) 965 return arp_req_set_public(net, r, dev); 966 967 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 968 if (r->arp_flags & ATF_PERM) 969 r->arp_flags |= ATF_COM; 970 if (!dev) { 971 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0); 972 973 if (IS_ERR(rt)) 974 return PTR_ERR(rt); 975 dev = rt->dst.dev; 976 ip_rt_put(rt); 977 if (!dev) 978 return -EINVAL; 979 } 980 switch (dev->type) { 981 #if IS_ENABLED(CONFIG_FDDI) 982 case ARPHRD_FDDI: 983 /* 984 * According to RFC 1390, FDDI devices should accept ARP 985 * hardware types of 1 (Ethernet). However, to be more 986 * robust, we'll accept hardware types of either 1 (Ethernet) 987 * or 6 (IEEE 802.2). 988 */ 989 if (r->arp_ha.sa_family != ARPHRD_FDDI && 990 r->arp_ha.sa_family != ARPHRD_ETHER && 991 r->arp_ha.sa_family != ARPHRD_IEEE802) 992 return -EINVAL; 993 break; 994 #endif 995 default: 996 if (r->arp_ha.sa_family != dev->type) 997 return -EINVAL; 998 break; 999 } 1000 1001 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev); 1002 err = PTR_ERR(neigh); 1003 if (!IS_ERR(neigh)) { 1004 unsigned int state = NUD_STALE; 1005 if (r->arp_flags & ATF_PERM) 1006 state = NUD_PERMANENT; 1007 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ? 1008 r->arp_ha.sa_data : NULL, state, 1009 NEIGH_UPDATE_F_OVERRIDE | 1010 NEIGH_UPDATE_F_ADMIN); 1011 neigh_release(neigh); 1012 } 1013 return err; 1014 } 1015 1016 static unsigned int arp_state_to_flags(struct neighbour *neigh) 1017 { 1018 if (neigh->nud_state&NUD_PERMANENT) 1019 return ATF_PERM | ATF_COM; 1020 else if (neigh->nud_state&NUD_VALID) 1021 return ATF_COM; 1022 else 1023 return 0; 1024 } 1025 1026 /* 1027 * Get an ARP cache entry. 1028 */ 1029 1030 static int arp_req_get(struct arpreq *r, struct net_device *dev) 1031 { 1032 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; 1033 struct neighbour *neigh; 1034 int err = -ENXIO; 1035 1036 neigh = neigh_lookup(&arp_tbl, &ip, dev); 1037 if (neigh) { 1038 if (!(neigh->nud_state & NUD_NOARP)) { 1039 read_lock_bh(&neigh->lock); 1040 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len); 1041 r->arp_flags = arp_state_to_flags(neigh); 1042 read_unlock_bh(&neigh->lock); 1043 r->arp_ha.sa_family = dev->type; 1044 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev)); 1045 err = 0; 1046 } 1047 neigh_release(neigh); 1048 } 1049 return err; 1050 } 1051 1052 static int arp_invalidate(struct net_device *dev, __be32 ip) 1053 { 1054 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev); 1055 int err = -ENXIO; 1056 1057 if (neigh) { 1058 if (neigh->nud_state & ~NUD_NOARP) 1059 err = neigh_update(neigh, NULL, NUD_FAILED, 1060 NEIGH_UPDATE_F_OVERRIDE| 1061 NEIGH_UPDATE_F_ADMIN); 1062 neigh_release(neigh); 1063 } 1064 1065 return err; 1066 } 1067 1068 static int arp_req_delete_public(struct net *net, struct arpreq *r, 1069 struct net_device *dev) 1070 { 1071 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; 1072 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 1073 1074 if (mask == htonl(0xFFFFFFFF)) 1075 return pneigh_delete(&arp_tbl, net, &ip, dev); 1076 1077 if (mask) 1078 return -EINVAL; 1079 1080 return arp_req_set_proxy(net, dev, 0); 1081 } 1082 1083 static int arp_req_delete(struct net *net, struct arpreq *r, 1084 struct net_device *dev) 1085 { 1086 __be32 ip; 1087 1088 if (r->arp_flags & ATF_PUBL) 1089 return arp_req_delete_public(net, r, dev); 1090 1091 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1092 if (!dev) { 1093 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0); 1094 if (IS_ERR(rt)) 1095 return PTR_ERR(rt); 1096 dev = rt->dst.dev; 1097 ip_rt_put(rt); 1098 if (!dev) 1099 return -EINVAL; 1100 } 1101 return arp_invalidate(dev, ip); 1102 } 1103 1104 /* 1105 * Handle an ARP layer I/O control request. 1106 */ 1107 1108 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg) 1109 { 1110 int err; 1111 struct arpreq r; 1112 struct net_device *dev = NULL; 1113 1114 switch (cmd) { 1115 case SIOCDARP: 1116 case SIOCSARP: 1117 if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) 1118 return -EPERM; 1119 case SIOCGARP: 1120 err = copy_from_user(&r, arg, sizeof(struct arpreq)); 1121 if (err) 1122 return -EFAULT; 1123 break; 1124 default: 1125 return -EINVAL; 1126 } 1127 1128 if (r.arp_pa.sa_family != AF_INET) 1129 return -EPFNOSUPPORT; 1130 1131 if (!(r.arp_flags & ATF_PUBL) && 1132 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB))) 1133 return -EINVAL; 1134 if (!(r.arp_flags & ATF_NETMASK)) 1135 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr = 1136 htonl(0xFFFFFFFFUL); 1137 rtnl_lock(); 1138 if (r.arp_dev[0]) { 1139 err = -ENODEV; 1140 dev = __dev_get_by_name(net, r.arp_dev); 1141 if (!dev) 1142 goto out; 1143 1144 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */ 1145 if (!r.arp_ha.sa_family) 1146 r.arp_ha.sa_family = dev->type; 1147 err = -EINVAL; 1148 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type) 1149 goto out; 1150 } else if (cmd == SIOCGARP) { 1151 err = -ENODEV; 1152 goto out; 1153 } 1154 1155 switch (cmd) { 1156 case SIOCDARP: 1157 err = arp_req_delete(net, &r, dev); 1158 break; 1159 case SIOCSARP: 1160 err = arp_req_set(net, &r, dev); 1161 break; 1162 case SIOCGARP: 1163 err = arp_req_get(&r, dev); 1164 break; 1165 } 1166 out: 1167 rtnl_unlock(); 1168 if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r))) 1169 err = -EFAULT; 1170 return err; 1171 } 1172 1173 static int arp_netdev_event(struct notifier_block *this, unsigned long event, 1174 void *ptr) 1175 { 1176 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 1177 struct netdev_notifier_change_info *change_info; 1178 1179 switch (event) { 1180 case NETDEV_CHANGEADDR: 1181 neigh_changeaddr(&arp_tbl, dev); 1182 rt_cache_flush(dev_net(dev)); 1183 break; 1184 case NETDEV_CHANGE: 1185 change_info = ptr; 1186 if (change_info->flags_changed & IFF_NOARP) 1187 neigh_changeaddr(&arp_tbl, dev); 1188 break; 1189 default: 1190 break; 1191 } 1192 1193 return NOTIFY_DONE; 1194 } 1195 1196 static struct notifier_block arp_netdev_notifier = { 1197 .notifier_call = arp_netdev_event, 1198 }; 1199 1200 /* Note, that it is not on notifier chain. 1201 It is necessary, that this routine was called after route cache will be 1202 flushed. 1203 */ 1204 void arp_ifdown(struct net_device *dev) 1205 { 1206 neigh_ifdown(&arp_tbl, dev); 1207 } 1208 1209 1210 /* 1211 * Called once on startup. 1212 */ 1213 1214 static struct packet_type arp_packet_type __read_mostly = { 1215 .type = cpu_to_be16(ETH_P_ARP), 1216 .func = arp_rcv, 1217 }; 1218 1219 static int arp_proc_init(void); 1220 1221 void __init arp_init(void) 1222 { 1223 neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl); 1224 1225 dev_add_pack(&arp_packet_type); 1226 arp_proc_init(); 1227 #ifdef CONFIG_SYSCTL 1228 neigh_sysctl_register(NULL, &arp_tbl.parms, NULL); 1229 #endif 1230 register_netdevice_notifier(&arp_netdev_notifier); 1231 } 1232 1233 #ifdef CONFIG_PROC_FS 1234 #if IS_ENABLED(CONFIG_AX25) 1235 1236 /* ------------------------------------------------------------------------ */ 1237 /* 1238 * ax25 -> ASCII conversion 1239 */ 1240 static char *ax2asc2(ax25_address *a, char *buf) 1241 { 1242 char c, *s; 1243 int n; 1244 1245 for (n = 0, s = buf; n < 6; n++) { 1246 c = (a->ax25_call[n] >> 1) & 0x7F; 1247 1248 if (c != ' ') 1249 *s++ = c; 1250 } 1251 1252 *s++ = '-'; 1253 n = (a->ax25_call[6] >> 1) & 0x0F; 1254 if (n > 9) { 1255 *s++ = '1'; 1256 n -= 10; 1257 } 1258 1259 *s++ = n + '0'; 1260 *s++ = '\0'; 1261 1262 if (*buf == '\0' || *buf == '-') 1263 return "*"; 1264 1265 return buf; 1266 } 1267 #endif /* CONFIG_AX25 */ 1268 1269 #define HBUFFERLEN 30 1270 1271 static void arp_format_neigh_entry(struct seq_file *seq, 1272 struct neighbour *n) 1273 { 1274 char hbuffer[HBUFFERLEN]; 1275 int k, j; 1276 char tbuf[16]; 1277 struct net_device *dev = n->dev; 1278 int hatype = dev->type; 1279 1280 read_lock(&n->lock); 1281 /* Convert hardware address to XX:XX:XX:XX ... form. */ 1282 #if IS_ENABLED(CONFIG_AX25) 1283 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM) 1284 ax2asc2((ax25_address *)n->ha, hbuffer); 1285 else { 1286 #endif 1287 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) { 1288 hbuffer[k++] = hex_asc_hi(n->ha[j]); 1289 hbuffer[k++] = hex_asc_lo(n->ha[j]); 1290 hbuffer[k++] = ':'; 1291 } 1292 if (k != 0) 1293 --k; 1294 hbuffer[k] = 0; 1295 #if IS_ENABLED(CONFIG_AX25) 1296 } 1297 #endif 1298 sprintf(tbuf, "%pI4", n->primary_key); 1299 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n", 1300 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name); 1301 read_unlock(&n->lock); 1302 } 1303 1304 static void arp_format_pneigh_entry(struct seq_file *seq, 1305 struct pneigh_entry *n) 1306 { 1307 struct net_device *dev = n->dev; 1308 int hatype = dev ? dev->type : 0; 1309 char tbuf[16]; 1310 1311 sprintf(tbuf, "%pI4", n->key); 1312 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n", 1313 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00", 1314 dev ? dev->name : "*"); 1315 } 1316 1317 static int arp_seq_show(struct seq_file *seq, void *v) 1318 { 1319 if (v == SEQ_START_TOKEN) { 1320 seq_puts(seq, "IP address HW type Flags " 1321 "HW address Mask Device\n"); 1322 } else { 1323 struct neigh_seq_state *state = seq->private; 1324 1325 if (state->flags & NEIGH_SEQ_IS_PNEIGH) 1326 arp_format_pneigh_entry(seq, v); 1327 else 1328 arp_format_neigh_entry(seq, v); 1329 } 1330 1331 return 0; 1332 } 1333 1334 static void *arp_seq_start(struct seq_file *seq, loff_t *pos) 1335 { 1336 /* Don't want to confuse "arp -a" w/ magic entries, 1337 * so we tell the generic iterator to skip NUD_NOARP. 1338 */ 1339 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP); 1340 } 1341 1342 /* ------------------------------------------------------------------------ */ 1343 1344 static const struct seq_operations arp_seq_ops = { 1345 .start = arp_seq_start, 1346 .next = neigh_seq_next, 1347 .stop = neigh_seq_stop, 1348 .show = arp_seq_show, 1349 }; 1350 1351 static int arp_seq_open(struct inode *inode, struct file *file) 1352 { 1353 return seq_open_net(inode, file, &arp_seq_ops, 1354 sizeof(struct neigh_seq_state)); 1355 } 1356 1357 static const struct file_operations arp_seq_fops = { 1358 .owner = THIS_MODULE, 1359 .open = arp_seq_open, 1360 .read = seq_read, 1361 .llseek = seq_lseek, 1362 .release = seq_release_net, 1363 }; 1364 1365 1366 static int __net_init arp_net_init(struct net *net) 1367 { 1368 if (!proc_create("arp", S_IRUGO, net->proc_net, &arp_seq_fops)) 1369 return -ENOMEM; 1370 return 0; 1371 } 1372 1373 static void __net_exit arp_net_exit(struct net *net) 1374 { 1375 remove_proc_entry("arp", net->proc_net); 1376 } 1377 1378 static struct pernet_operations arp_net_ops = { 1379 .init = arp_net_init, 1380 .exit = arp_net_exit, 1381 }; 1382 1383 static int __init arp_proc_init(void) 1384 { 1385 return register_pernet_subsys(&arp_net_ops); 1386 } 1387 1388 #else /* CONFIG_PROC_FS */ 1389 1390 static int __init arp_proc_init(void) 1391 { 1392 return 0; 1393 } 1394 1395 #endif /* CONFIG_PROC_FS */ 1396