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 #include <net/dst_metadata.h> 117 #include <net/ip_tunnels.h> 118 119 #include <linux/uaccess.h> 120 121 #include <linux/netfilter_arp.h> 122 123 /* 124 * Interface to generic neighbour cache. 125 */ 126 static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd); 127 static bool arp_key_eq(const struct neighbour *n, const void *pkey); 128 static int arp_constructor(struct neighbour *neigh); 129 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb); 130 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb); 131 static void parp_redo(struct sk_buff *skb); 132 133 static const struct neigh_ops arp_generic_ops = { 134 .family = AF_INET, 135 .solicit = arp_solicit, 136 .error_report = arp_error_report, 137 .output = neigh_resolve_output, 138 .connected_output = neigh_connected_output, 139 }; 140 141 static const struct neigh_ops arp_hh_ops = { 142 .family = AF_INET, 143 .solicit = arp_solicit, 144 .error_report = arp_error_report, 145 .output = neigh_resolve_output, 146 .connected_output = neigh_resolve_output, 147 }; 148 149 static const struct neigh_ops arp_direct_ops = { 150 .family = AF_INET, 151 .output = neigh_direct_output, 152 .connected_output = neigh_direct_output, 153 }; 154 155 struct neigh_table arp_tbl = { 156 .family = AF_INET, 157 .key_len = 4, 158 .protocol = cpu_to_be16(ETH_P_IP), 159 .hash = arp_hash, 160 .key_eq = arp_key_eq, 161 .constructor = arp_constructor, 162 .proxy_redo = parp_redo, 163 .id = "arp_cache", 164 .parms = { 165 .tbl = &arp_tbl, 166 .reachable_time = 30 * HZ, 167 .data = { 168 [NEIGH_VAR_MCAST_PROBES] = 3, 169 [NEIGH_VAR_UCAST_PROBES] = 3, 170 [NEIGH_VAR_RETRANS_TIME] = 1 * HZ, 171 [NEIGH_VAR_BASE_REACHABLE_TIME] = 30 * HZ, 172 [NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ, 173 [NEIGH_VAR_GC_STALETIME] = 60 * HZ, 174 [NEIGH_VAR_QUEUE_LEN_BYTES] = 64 * 1024, 175 [NEIGH_VAR_PROXY_QLEN] = 64, 176 [NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ, 177 [NEIGH_VAR_PROXY_DELAY] = (8 * HZ) / 10, 178 [NEIGH_VAR_LOCKTIME] = 1 * HZ, 179 }, 180 }, 181 .gc_interval = 30 * HZ, 182 .gc_thresh1 = 128, 183 .gc_thresh2 = 512, 184 .gc_thresh3 = 1024, 185 }; 186 EXPORT_SYMBOL(arp_tbl); 187 188 int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir) 189 { 190 switch (dev->type) { 191 case ARPHRD_ETHER: 192 case ARPHRD_FDDI: 193 case ARPHRD_IEEE802: 194 ip_eth_mc_map(addr, haddr); 195 return 0; 196 case ARPHRD_INFINIBAND: 197 ip_ib_mc_map(addr, dev->broadcast, haddr); 198 return 0; 199 case ARPHRD_IPGRE: 200 ip_ipgre_mc_map(addr, dev->broadcast, haddr); 201 return 0; 202 default: 203 if (dir) { 204 memcpy(haddr, dev->broadcast, dev->addr_len); 205 return 0; 206 } 207 } 208 return -EINVAL; 209 } 210 211 212 static u32 arp_hash(const void *pkey, 213 const struct net_device *dev, 214 __u32 *hash_rnd) 215 { 216 return arp_hashfn(pkey, dev, hash_rnd); 217 } 218 219 static bool arp_key_eq(const struct neighbour *neigh, const void *pkey) 220 { 221 return neigh_key_eq32(neigh, pkey); 222 } 223 224 static int arp_constructor(struct neighbour *neigh) 225 { 226 __be32 addr = *(__be32 *)neigh->primary_key; 227 struct net_device *dev = neigh->dev; 228 struct in_device *in_dev; 229 struct neigh_parms *parms; 230 231 rcu_read_lock(); 232 in_dev = __in_dev_get_rcu(dev); 233 if (!in_dev) { 234 rcu_read_unlock(); 235 return -EINVAL; 236 } 237 238 neigh->type = inet_addr_type_dev_table(dev_net(dev), dev, addr); 239 240 parms = in_dev->arp_parms; 241 __neigh_parms_put(neigh->parms); 242 neigh->parms = neigh_parms_clone(parms); 243 rcu_read_unlock(); 244 245 if (!dev->header_ops) { 246 neigh->nud_state = NUD_NOARP; 247 neigh->ops = &arp_direct_ops; 248 neigh->output = neigh_direct_output; 249 } else { 250 /* Good devices (checked by reading texts, but only Ethernet is 251 tested) 252 253 ARPHRD_ETHER: (ethernet, apfddi) 254 ARPHRD_FDDI: (fddi) 255 ARPHRD_IEEE802: (tr) 256 ARPHRD_METRICOM: (strip) 257 ARPHRD_ARCNET: 258 etc. etc. etc. 259 260 ARPHRD_IPDDP will also work, if author repairs it. 261 I did not it, because this driver does not work even 262 in old paradigm. 263 */ 264 265 if (neigh->type == RTN_MULTICAST) { 266 neigh->nud_state = NUD_NOARP; 267 arp_mc_map(addr, neigh->ha, dev, 1); 268 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) { 269 neigh->nud_state = NUD_NOARP; 270 memcpy(neigh->ha, dev->dev_addr, dev->addr_len); 271 } else if (neigh->type == RTN_BROADCAST || 272 (dev->flags & IFF_POINTOPOINT)) { 273 neigh->nud_state = NUD_NOARP; 274 memcpy(neigh->ha, dev->broadcast, dev->addr_len); 275 } 276 277 if (dev->header_ops->cache) 278 neigh->ops = &arp_hh_ops; 279 else 280 neigh->ops = &arp_generic_ops; 281 282 if (neigh->nud_state & NUD_VALID) 283 neigh->output = neigh->ops->connected_output; 284 else 285 neigh->output = neigh->ops->output; 286 } 287 return 0; 288 } 289 290 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb) 291 { 292 dst_link_failure(skb); 293 kfree_skb(skb); 294 } 295 296 /* Create and send an arp packet. */ 297 static void arp_send_dst(int type, int ptype, __be32 dest_ip, 298 struct net_device *dev, __be32 src_ip, 299 const unsigned char *dest_hw, 300 const unsigned char *src_hw, 301 const unsigned char *target_hw, 302 struct dst_entry *dst) 303 { 304 struct sk_buff *skb; 305 306 /* arp on this interface. */ 307 if (dev->flags & IFF_NOARP) 308 return; 309 310 skb = arp_create(type, ptype, dest_ip, dev, src_ip, 311 dest_hw, src_hw, target_hw); 312 if (!skb) 313 return; 314 315 skb_dst_set(skb, dst); 316 arp_xmit(skb); 317 } 318 319 void arp_send(int type, int ptype, __be32 dest_ip, 320 struct net_device *dev, __be32 src_ip, 321 const unsigned char *dest_hw, const unsigned char *src_hw, 322 const unsigned char *target_hw) 323 { 324 arp_send_dst(type, ptype, dest_ip, dev, src_ip, dest_hw, src_hw, 325 target_hw, NULL); 326 } 327 EXPORT_SYMBOL(arp_send); 328 329 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb) 330 { 331 __be32 saddr = 0; 332 u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL; 333 struct net_device *dev = neigh->dev; 334 __be32 target = *(__be32 *)neigh->primary_key; 335 int probes = atomic_read(&neigh->probes); 336 struct in_device *in_dev; 337 struct dst_entry *dst = NULL; 338 339 rcu_read_lock(); 340 in_dev = __in_dev_get_rcu(dev); 341 if (!in_dev) { 342 rcu_read_unlock(); 343 return; 344 } 345 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) { 346 default: 347 case 0: /* By default announce any local IP */ 348 if (skb && inet_addr_type_dev_table(dev_net(dev), dev, 349 ip_hdr(skb)->saddr) == RTN_LOCAL) 350 saddr = ip_hdr(skb)->saddr; 351 break; 352 case 1: /* Restrict announcements of saddr in same subnet */ 353 if (!skb) 354 break; 355 saddr = ip_hdr(skb)->saddr; 356 if (inet_addr_type_dev_table(dev_net(dev), dev, 357 saddr) == RTN_LOCAL) { 358 /* saddr should be known to target */ 359 if (inet_addr_onlink(in_dev, target, saddr)) 360 break; 361 } 362 saddr = 0; 363 break; 364 case 2: /* Avoid secondary IPs, get a primary/preferred one */ 365 break; 366 } 367 rcu_read_unlock(); 368 369 if (!saddr) 370 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK); 371 372 probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES); 373 if (probes < 0) { 374 if (!(neigh->nud_state & NUD_VALID)) 375 pr_debug("trying to ucast probe in NUD_INVALID\n"); 376 neigh_ha_snapshot(dst_ha, neigh, dev); 377 dst_hw = dst_ha; 378 } else { 379 probes -= NEIGH_VAR(neigh->parms, APP_PROBES); 380 if (probes < 0) { 381 neigh_app_ns(neigh); 382 return; 383 } 384 } 385 386 if (skb && !(dev->priv_flags & IFF_XMIT_DST_RELEASE)) 387 dst = dst_clone(skb_dst(skb)); 388 arp_send_dst(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr, 389 dst_hw, dev->dev_addr, NULL, dst); 390 } 391 392 static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip) 393 { 394 struct net *net = dev_net(in_dev->dev); 395 int scope; 396 397 switch (IN_DEV_ARP_IGNORE(in_dev)) { 398 case 0: /* Reply, the tip is already validated */ 399 return 0; 400 case 1: /* Reply only if tip is configured on the incoming interface */ 401 sip = 0; 402 scope = RT_SCOPE_HOST; 403 break; 404 case 2: /* 405 * Reply only if tip is configured on the incoming interface 406 * and is in same subnet as sip 407 */ 408 scope = RT_SCOPE_HOST; 409 break; 410 case 3: /* Do not reply for scope host addresses */ 411 sip = 0; 412 scope = RT_SCOPE_LINK; 413 in_dev = NULL; 414 break; 415 case 4: /* Reserved */ 416 case 5: 417 case 6: 418 case 7: 419 return 0; 420 case 8: /* Do not reply */ 421 return 1; 422 default: 423 return 0; 424 } 425 return !inet_confirm_addr(net, in_dev, sip, tip, scope); 426 } 427 428 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev) 429 { 430 struct rtable *rt; 431 int flag = 0; 432 /*unsigned long now; */ 433 struct net *net = dev_net(dev); 434 435 rt = ip_route_output(net, sip, tip, 0, 0); 436 if (IS_ERR(rt)) 437 return 1; 438 if (rt->dst.dev != dev) { 439 NET_INC_STATS_BH(net, LINUX_MIB_ARPFILTER); 440 flag = 1; 441 } 442 ip_rt_put(rt); 443 return flag; 444 } 445 446 /* 447 * Check if we can use proxy ARP for this path 448 */ 449 static inline int arp_fwd_proxy(struct in_device *in_dev, 450 struct net_device *dev, struct rtable *rt) 451 { 452 struct in_device *out_dev; 453 int imi, omi = -1; 454 455 if (rt->dst.dev == dev) 456 return 0; 457 458 if (!IN_DEV_PROXY_ARP(in_dev)) 459 return 0; 460 imi = IN_DEV_MEDIUM_ID(in_dev); 461 if (imi == 0) 462 return 1; 463 if (imi == -1) 464 return 0; 465 466 /* place to check for proxy_arp for routes */ 467 468 out_dev = __in_dev_get_rcu(rt->dst.dev); 469 if (out_dev) 470 omi = IN_DEV_MEDIUM_ID(out_dev); 471 472 return omi != imi && omi != -1; 473 } 474 475 /* 476 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev) 477 * 478 * RFC3069 supports proxy arp replies back to the same interface. This 479 * is done to support (ethernet) switch features, like RFC 3069, where 480 * the individual ports are not allowed to communicate with each 481 * other, BUT they are allowed to talk to the upstream router. As 482 * described in RFC 3069, it is possible to allow these hosts to 483 * communicate through the upstream router, by proxy_arp'ing. 484 * 485 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation" 486 * 487 * This technology is known by different names: 488 * In RFC 3069 it is called VLAN Aggregation. 489 * Cisco and Allied Telesyn call it Private VLAN. 490 * Hewlett-Packard call it Source-Port filtering or port-isolation. 491 * Ericsson call it MAC-Forced Forwarding (RFC Draft). 492 * 493 */ 494 static inline int arp_fwd_pvlan(struct in_device *in_dev, 495 struct net_device *dev, struct rtable *rt, 496 __be32 sip, __be32 tip) 497 { 498 /* Private VLAN is only concerned about the same ethernet segment */ 499 if (rt->dst.dev != dev) 500 return 0; 501 502 /* Don't reply on self probes (often done by windowz boxes)*/ 503 if (sip == tip) 504 return 0; 505 506 if (IN_DEV_PROXY_ARP_PVLAN(in_dev)) 507 return 1; 508 else 509 return 0; 510 } 511 512 /* 513 * Interface to link layer: send routine and receive handler. 514 */ 515 516 /* 517 * Create an arp packet. If dest_hw is not set, we create a broadcast 518 * message. 519 */ 520 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip, 521 struct net_device *dev, __be32 src_ip, 522 const unsigned char *dest_hw, 523 const unsigned char *src_hw, 524 const unsigned char *target_hw) 525 { 526 struct sk_buff *skb; 527 struct arphdr *arp; 528 unsigned char *arp_ptr; 529 int hlen = LL_RESERVED_SPACE(dev); 530 int tlen = dev->needed_tailroom; 531 532 /* 533 * Allocate a buffer 534 */ 535 536 skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC); 537 if (!skb) 538 return NULL; 539 540 skb_reserve(skb, hlen); 541 skb_reset_network_header(skb); 542 arp = (struct arphdr *) skb_put(skb, arp_hdr_len(dev)); 543 skb->dev = dev; 544 skb->protocol = htons(ETH_P_ARP); 545 if (!src_hw) 546 src_hw = dev->dev_addr; 547 if (!dest_hw) 548 dest_hw = dev->broadcast; 549 550 /* 551 * Fill the device header for the ARP frame 552 */ 553 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0) 554 goto out; 555 556 /* 557 * Fill out the arp protocol part. 558 * 559 * The arp hardware type should match the device type, except for FDDI, 560 * which (according to RFC 1390) should always equal 1 (Ethernet). 561 */ 562 /* 563 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the 564 * DIX code for the protocol. Make these device structure fields. 565 */ 566 switch (dev->type) { 567 default: 568 arp->ar_hrd = htons(dev->type); 569 arp->ar_pro = htons(ETH_P_IP); 570 break; 571 572 #if IS_ENABLED(CONFIG_AX25) 573 case ARPHRD_AX25: 574 arp->ar_hrd = htons(ARPHRD_AX25); 575 arp->ar_pro = htons(AX25_P_IP); 576 break; 577 578 #if IS_ENABLED(CONFIG_NETROM) 579 case ARPHRD_NETROM: 580 arp->ar_hrd = htons(ARPHRD_NETROM); 581 arp->ar_pro = htons(AX25_P_IP); 582 break; 583 #endif 584 #endif 585 586 #if IS_ENABLED(CONFIG_FDDI) 587 case ARPHRD_FDDI: 588 arp->ar_hrd = htons(ARPHRD_ETHER); 589 arp->ar_pro = htons(ETH_P_IP); 590 break; 591 #endif 592 } 593 594 arp->ar_hln = dev->addr_len; 595 arp->ar_pln = 4; 596 arp->ar_op = htons(type); 597 598 arp_ptr = (unsigned char *)(arp + 1); 599 600 memcpy(arp_ptr, src_hw, dev->addr_len); 601 arp_ptr += dev->addr_len; 602 memcpy(arp_ptr, &src_ip, 4); 603 arp_ptr += 4; 604 605 switch (dev->type) { 606 #if IS_ENABLED(CONFIG_FIREWIRE_NET) 607 case ARPHRD_IEEE1394: 608 break; 609 #endif 610 default: 611 if (target_hw) 612 memcpy(arp_ptr, target_hw, dev->addr_len); 613 else 614 memset(arp_ptr, 0, dev->addr_len); 615 arp_ptr += dev->addr_len; 616 } 617 memcpy(arp_ptr, &dest_ip, 4); 618 619 return skb; 620 621 out: 622 kfree_skb(skb); 623 return NULL; 624 } 625 EXPORT_SYMBOL(arp_create); 626 627 /* 628 * Send an arp packet. 629 */ 630 void arp_xmit(struct sk_buff *skb) 631 { 632 /* Send it off, maybe filter it using firewalling first. */ 633 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, NULL, skb, 634 NULL, skb->dev, dev_queue_xmit_sk); 635 } 636 EXPORT_SYMBOL(arp_xmit); 637 638 /* 639 * Process an arp request. 640 */ 641 642 static int arp_process(struct sock *sk, struct sk_buff *skb) 643 { 644 struct net_device *dev = skb->dev; 645 struct in_device *in_dev = __in_dev_get_rcu(dev); 646 struct arphdr *arp; 647 unsigned char *arp_ptr; 648 struct rtable *rt; 649 unsigned char *sha; 650 __be32 sip, tip; 651 u16 dev_type = dev->type; 652 int addr_type; 653 struct neighbour *n; 654 struct net *net = dev_net(dev); 655 struct dst_entry *reply_dst = NULL; 656 bool is_garp = false; 657 658 /* arp_rcv below verifies the ARP header and verifies the device 659 * is ARP'able. 660 */ 661 662 if (!in_dev) 663 goto out; 664 665 arp = arp_hdr(skb); 666 667 switch (dev_type) { 668 default: 669 if (arp->ar_pro != htons(ETH_P_IP) || 670 htons(dev_type) != arp->ar_hrd) 671 goto out; 672 break; 673 case ARPHRD_ETHER: 674 case ARPHRD_FDDI: 675 case ARPHRD_IEEE802: 676 /* 677 * ETHERNET, and Fibre Channel (which are IEEE 802 678 * devices, according to RFC 2625) devices will accept ARP 679 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2). 680 * This is the case also of FDDI, where the RFC 1390 says that 681 * FDDI devices should accept ARP hardware of (1) Ethernet, 682 * however, to be more robust, we'll accept both 1 (Ethernet) 683 * or 6 (IEEE 802.2) 684 */ 685 if ((arp->ar_hrd != htons(ARPHRD_ETHER) && 686 arp->ar_hrd != htons(ARPHRD_IEEE802)) || 687 arp->ar_pro != htons(ETH_P_IP)) 688 goto out; 689 break; 690 case ARPHRD_AX25: 691 if (arp->ar_pro != htons(AX25_P_IP) || 692 arp->ar_hrd != htons(ARPHRD_AX25)) 693 goto out; 694 break; 695 case ARPHRD_NETROM: 696 if (arp->ar_pro != htons(AX25_P_IP) || 697 arp->ar_hrd != htons(ARPHRD_NETROM)) 698 goto out; 699 break; 700 } 701 702 /* Understand only these message types */ 703 704 if (arp->ar_op != htons(ARPOP_REPLY) && 705 arp->ar_op != htons(ARPOP_REQUEST)) 706 goto out; 707 708 /* 709 * Extract fields 710 */ 711 arp_ptr = (unsigned char *)(arp + 1); 712 sha = arp_ptr; 713 arp_ptr += dev->addr_len; 714 memcpy(&sip, arp_ptr, 4); 715 arp_ptr += 4; 716 switch (dev_type) { 717 #if IS_ENABLED(CONFIG_FIREWIRE_NET) 718 case ARPHRD_IEEE1394: 719 break; 720 #endif 721 default: 722 arp_ptr += dev->addr_len; 723 } 724 memcpy(&tip, arp_ptr, 4); 725 /* 726 * Check for bad requests for 127.x.x.x and requests for multicast 727 * addresses. If this is one such, delete it. 728 */ 729 if (ipv4_is_multicast(tip) || 730 (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip))) 731 goto out; 732 733 /* 734 * Special case: We must set Frame Relay source Q.922 address 735 */ 736 if (dev_type == ARPHRD_DLCI) 737 sha = dev->broadcast; 738 739 /* 740 * Process entry. The idea here is we want to send a reply if it is a 741 * request for us or if it is a request for someone else that we hold 742 * a proxy for. We want to add an entry to our cache if it is a reply 743 * to us or if it is a request for our address. 744 * (The assumption for this last is that if someone is requesting our 745 * address, they are probably intending to talk to us, so it saves time 746 * if we cache their address. Their address is also probably not in 747 * our cache, since ours is not in their cache.) 748 * 749 * Putting this another way, we only care about replies if they are to 750 * us, in which case we add them to the cache. For requests, we care 751 * about those for us and those for our proxies. We reply to both, 752 * and in the case of requests for us we add the requester to the arp 753 * cache. 754 */ 755 756 if (arp->ar_op == htons(ARPOP_REQUEST) && skb_metadata_dst(skb)) 757 reply_dst = (struct dst_entry *) 758 iptunnel_metadata_reply(skb_metadata_dst(skb), 759 GFP_ATOMIC); 760 761 /* Special case: IPv4 duplicate address detection packet (RFC2131) */ 762 if (sip == 0) { 763 if (arp->ar_op == htons(ARPOP_REQUEST) && 764 inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL && 765 !arp_ignore(in_dev, sip, tip)) 766 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, 767 sha, dev->dev_addr, sha, reply_dst); 768 goto out; 769 } 770 771 if (arp->ar_op == htons(ARPOP_REQUEST) && 772 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) { 773 774 rt = skb_rtable(skb); 775 addr_type = rt->rt_type; 776 777 if (addr_type == RTN_LOCAL) { 778 int dont_send; 779 780 dont_send = arp_ignore(in_dev, sip, tip); 781 if (!dont_send && IN_DEV_ARPFILTER(in_dev)) 782 dont_send = arp_filter(sip, tip, dev); 783 if (!dont_send) { 784 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 785 if (n) { 786 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, 787 sip, dev, tip, sha, 788 dev->dev_addr, sha, 789 reply_dst); 790 neigh_release(n); 791 } 792 } 793 goto out; 794 } else if (IN_DEV_FORWARD(in_dev)) { 795 if (addr_type == RTN_UNICAST && 796 (arp_fwd_proxy(in_dev, dev, rt) || 797 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) || 798 (rt->dst.dev != dev && 799 pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) { 800 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 801 if (n) 802 neigh_release(n); 803 804 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED || 805 skb->pkt_type == PACKET_HOST || 806 NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) { 807 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, 808 sip, dev, tip, sha, 809 dev->dev_addr, sha, 810 reply_dst); 811 } else { 812 pneigh_enqueue(&arp_tbl, 813 in_dev->arp_parms, skb); 814 return 0; 815 } 816 goto out; 817 } 818 } 819 } 820 821 /* Update our ARP tables */ 822 823 n = __neigh_lookup(&arp_tbl, &sip, dev, 0); 824 825 if (IN_DEV_ARP_ACCEPT(in_dev)) { 826 unsigned int addr_type = inet_addr_type_dev_table(net, dev, sip); 827 828 /* Unsolicited ARP is not accepted by default. 829 It is possible, that this option should be enabled for some 830 devices (strip is candidate) 831 */ 832 is_garp = arp->ar_op == htons(ARPOP_REQUEST) && tip == sip && 833 addr_type == RTN_UNICAST; 834 835 if (!n && 836 ((arp->ar_op == htons(ARPOP_REPLY) && 837 addr_type == RTN_UNICAST) || is_garp)) 838 n = __neigh_lookup(&arp_tbl, &sip, dev, 1); 839 } 840 841 if (n) { 842 int state = NUD_REACHABLE; 843 int override; 844 845 /* If several different ARP replies follows back-to-back, 846 use the FIRST one. It is possible, if several proxy 847 agents are active. Taking the first reply prevents 848 arp trashing and chooses the fastest router. 849 */ 850 override = time_after(jiffies, 851 n->updated + 852 NEIGH_VAR(n->parms, LOCKTIME)) || 853 is_garp; 854 855 /* Broadcast replies and request packets 856 do not assert neighbour reachability. 857 */ 858 if (arp->ar_op != htons(ARPOP_REPLY) || 859 skb->pkt_type != PACKET_HOST) 860 state = NUD_STALE; 861 neigh_update(n, sha, state, 862 override ? NEIGH_UPDATE_F_OVERRIDE : 0); 863 neigh_release(n); 864 } 865 866 out: 867 consume_skb(skb); 868 return 0; 869 } 870 871 static void parp_redo(struct sk_buff *skb) 872 { 873 arp_process(NULL, skb); 874 } 875 876 877 /* 878 * Receive an arp request from the device layer. 879 */ 880 881 static int arp_rcv(struct sk_buff *skb, struct net_device *dev, 882 struct packet_type *pt, struct net_device *orig_dev) 883 { 884 const struct arphdr *arp; 885 886 /* do not tweak dropwatch on an ARP we will ignore */ 887 if (dev->flags & IFF_NOARP || 888 skb->pkt_type == PACKET_OTHERHOST || 889 skb->pkt_type == PACKET_LOOPBACK) 890 goto consumeskb; 891 892 skb = skb_share_check(skb, GFP_ATOMIC); 893 if (!skb) 894 goto out_of_mem; 895 896 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */ 897 if (!pskb_may_pull(skb, arp_hdr_len(dev))) 898 goto freeskb; 899 900 arp = arp_hdr(skb); 901 if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4) 902 goto freeskb; 903 904 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb)); 905 906 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, NULL, skb, 907 dev, NULL, arp_process); 908 909 consumeskb: 910 consume_skb(skb); 911 return 0; 912 freeskb: 913 kfree_skb(skb); 914 out_of_mem: 915 return 0; 916 } 917 918 /* 919 * User level interface (ioctl) 920 */ 921 922 /* 923 * Set (create) an ARP cache entry. 924 */ 925 926 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on) 927 { 928 if (!dev) { 929 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on; 930 return 0; 931 } 932 if (__in_dev_get_rtnl(dev)) { 933 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on); 934 return 0; 935 } 936 return -ENXIO; 937 } 938 939 static int arp_req_set_public(struct net *net, struct arpreq *r, 940 struct net_device *dev) 941 { 942 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 943 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 944 945 if (mask && mask != htonl(0xFFFFFFFF)) 946 return -EINVAL; 947 if (!dev && (r->arp_flags & ATF_COM)) { 948 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family, 949 r->arp_ha.sa_data); 950 if (!dev) 951 return -ENODEV; 952 } 953 if (mask) { 954 if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1)) 955 return -ENOBUFS; 956 return 0; 957 } 958 959 return arp_req_set_proxy(net, dev, 1); 960 } 961 962 static int arp_req_set(struct net *net, struct arpreq *r, 963 struct net_device *dev) 964 { 965 __be32 ip; 966 struct neighbour *neigh; 967 int err; 968 969 if (r->arp_flags & ATF_PUBL) 970 return arp_req_set_public(net, r, dev); 971 972 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 973 if (r->arp_flags & ATF_PERM) 974 r->arp_flags |= ATF_COM; 975 if (!dev) { 976 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0); 977 978 if (IS_ERR(rt)) 979 return PTR_ERR(rt); 980 dev = rt->dst.dev; 981 ip_rt_put(rt); 982 if (!dev) 983 return -EINVAL; 984 } 985 switch (dev->type) { 986 #if IS_ENABLED(CONFIG_FDDI) 987 case ARPHRD_FDDI: 988 /* 989 * According to RFC 1390, FDDI devices should accept ARP 990 * hardware types of 1 (Ethernet). However, to be more 991 * robust, we'll accept hardware types of either 1 (Ethernet) 992 * or 6 (IEEE 802.2). 993 */ 994 if (r->arp_ha.sa_family != ARPHRD_FDDI && 995 r->arp_ha.sa_family != ARPHRD_ETHER && 996 r->arp_ha.sa_family != ARPHRD_IEEE802) 997 return -EINVAL; 998 break; 999 #endif 1000 default: 1001 if (r->arp_ha.sa_family != dev->type) 1002 return -EINVAL; 1003 break; 1004 } 1005 1006 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev); 1007 err = PTR_ERR(neigh); 1008 if (!IS_ERR(neigh)) { 1009 unsigned int state = NUD_STALE; 1010 if (r->arp_flags & ATF_PERM) 1011 state = NUD_PERMANENT; 1012 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ? 1013 r->arp_ha.sa_data : NULL, state, 1014 NEIGH_UPDATE_F_OVERRIDE | 1015 NEIGH_UPDATE_F_ADMIN); 1016 neigh_release(neigh); 1017 } 1018 return err; 1019 } 1020 1021 static unsigned int arp_state_to_flags(struct neighbour *neigh) 1022 { 1023 if (neigh->nud_state&NUD_PERMANENT) 1024 return ATF_PERM | ATF_COM; 1025 else if (neigh->nud_state&NUD_VALID) 1026 return ATF_COM; 1027 else 1028 return 0; 1029 } 1030 1031 /* 1032 * Get an ARP cache entry. 1033 */ 1034 1035 static int arp_req_get(struct arpreq *r, struct net_device *dev) 1036 { 1037 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; 1038 struct neighbour *neigh; 1039 int err = -ENXIO; 1040 1041 neigh = neigh_lookup(&arp_tbl, &ip, dev); 1042 if (neigh) { 1043 if (!(neigh->nud_state & NUD_NOARP)) { 1044 read_lock_bh(&neigh->lock); 1045 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len); 1046 r->arp_flags = arp_state_to_flags(neigh); 1047 read_unlock_bh(&neigh->lock); 1048 r->arp_ha.sa_family = dev->type; 1049 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev)); 1050 err = 0; 1051 } 1052 neigh_release(neigh); 1053 } 1054 return err; 1055 } 1056 1057 static int arp_invalidate(struct net_device *dev, __be32 ip) 1058 { 1059 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev); 1060 int err = -ENXIO; 1061 1062 if (neigh) { 1063 if (neigh->nud_state & ~NUD_NOARP) 1064 err = neigh_update(neigh, NULL, NUD_FAILED, 1065 NEIGH_UPDATE_F_OVERRIDE| 1066 NEIGH_UPDATE_F_ADMIN); 1067 neigh_release(neigh); 1068 } 1069 1070 return err; 1071 } 1072 1073 static int arp_req_delete_public(struct net *net, struct arpreq *r, 1074 struct net_device *dev) 1075 { 1076 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; 1077 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 1078 1079 if (mask == htonl(0xFFFFFFFF)) 1080 return pneigh_delete(&arp_tbl, net, &ip, dev); 1081 1082 if (mask) 1083 return -EINVAL; 1084 1085 return arp_req_set_proxy(net, dev, 0); 1086 } 1087 1088 static int arp_req_delete(struct net *net, struct arpreq *r, 1089 struct net_device *dev) 1090 { 1091 __be32 ip; 1092 1093 if (r->arp_flags & ATF_PUBL) 1094 return arp_req_delete_public(net, r, dev); 1095 1096 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1097 if (!dev) { 1098 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0); 1099 if (IS_ERR(rt)) 1100 return PTR_ERR(rt); 1101 dev = rt->dst.dev; 1102 ip_rt_put(rt); 1103 if (!dev) 1104 return -EINVAL; 1105 } 1106 return arp_invalidate(dev, ip); 1107 } 1108 1109 /* 1110 * Handle an ARP layer I/O control request. 1111 */ 1112 1113 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg) 1114 { 1115 int err; 1116 struct arpreq r; 1117 struct net_device *dev = NULL; 1118 1119 switch (cmd) { 1120 case SIOCDARP: 1121 case SIOCSARP: 1122 if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) 1123 return -EPERM; 1124 case SIOCGARP: 1125 err = copy_from_user(&r, arg, sizeof(struct arpreq)); 1126 if (err) 1127 return -EFAULT; 1128 break; 1129 default: 1130 return -EINVAL; 1131 } 1132 1133 if (r.arp_pa.sa_family != AF_INET) 1134 return -EPFNOSUPPORT; 1135 1136 if (!(r.arp_flags & ATF_PUBL) && 1137 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB))) 1138 return -EINVAL; 1139 if (!(r.arp_flags & ATF_NETMASK)) 1140 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr = 1141 htonl(0xFFFFFFFFUL); 1142 rtnl_lock(); 1143 if (r.arp_dev[0]) { 1144 err = -ENODEV; 1145 dev = __dev_get_by_name(net, r.arp_dev); 1146 if (!dev) 1147 goto out; 1148 1149 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */ 1150 if (!r.arp_ha.sa_family) 1151 r.arp_ha.sa_family = dev->type; 1152 err = -EINVAL; 1153 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type) 1154 goto out; 1155 } else if (cmd == SIOCGARP) { 1156 err = -ENODEV; 1157 goto out; 1158 } 1159 1160 switch (cmd) { 1161 case SIOCDARP: 1162 err = arp_req_delete(net, &r, dev); 1163 break; 1164 case SIOCSARP: 1165 err = arp_req_set(net, &r, dev); 1166 break; 1167 case SIOCGARP: 1168 err = arp_req_get(&r, dev); 1169 break; 1170 } 1171 out: 1172 rtnl_unlock(); 1173 if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r))) 1174 err = -EFAULT; 1175 return err; 1176 } 1177 1178 static int arp_netdev_event(struct notifier_block *this, unsigned long event, 1179 void *ptr) 1180 { 1181 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 1182 struct netdev_notifier_change_info *change_info; 1183 1184 switch (event) { 1185 case NETDEV_CHANGEADDR: 1186 neigh_changeaddr(&arp_tbl, dev); 1187 rt_cache_flush(dev_net(dev)); 1188 break; 1189 case NETDEV_CHANGE: 1190 change_info = ptr; 1191 if (change_info->flags_changed & IFF_NOARP) 1192 neigh_changeaddr(&arp_tbl, dev); 1193 break; 1194 default: 1195 break; 1196 } 1197 1198 return NOTIFY_DONE; 1199 } 1200 1201 static struct notifier_block arp_netdev_notifier = { 1202 .notifier_call = arp_netdev_event, 1203 }; 1204 1205 /* Note, that it is not on notifier chain. 1206 It is necessary, that this routine was called after route cache will be 1207 flushed. 1208 */ 1209 void arp_ifdown(struct net_device *dev) 1210 { 1211 neigh_ifdown(&arp_tbl, dev); 1212 } 1213 1214 1215 /* 1216 * Called once on startup. 1217 */ 1218 1219 static struct packet_type arp_packet_type __read_mostly = { 1220 .type = cpu_to_be16(ETH_P_ARP), 1221 .func = arp_rcv, 1222 }; 1223 1224 static int arp_proc_init(void); 1225 1226 void __init arp_init(void) 1227 { 1228 neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl); 1229 1230 dev_add_pack(&arp_packet_type); 1231 arp_proc_init(); 1232 #ifdef CONFIG_SYSCTL 1233 neigh_sysctl_register(NULL, &arp_tbl.parms, NULL); 1234 #endif 1235 register_netdevice_notifier(&arp_netdev_notifier); 1236 } 1237 1238 #ifdef CONFIG_PROC_FS 1239 #if IS_ENABLED(CONFIG_AX25) 1240 1241 /* ------------------------------------------------------------------------ */ 1242 /* 1243 * ax25 -> ASCII conversion 1244 */ 1245 static char *ax2asc2(ax25_address *a, char *buf) 1246 { 1247 char c, *s; 1248 int n; 1249 1250 for (n = 0, s = buf; n < 6; n++) { 1251 c = (a->ax25_call[n] >> 1) & 0x7F; 1252 1253 if (c != ' ') 1254 *s++ = c; 1255 } 1256 1257 *s++ = '-'; 1258 n = (a->ax25_call[6] >> 1) & 0x0F; 1259 if (n > 9) { 1260 *s++ = '1'; 1261 n -= 10; 1262 } 1263 1264 *s++ = n + '0'; 1265 *s++ = '\0'; 1266 1267 if (*buf == '\0' || *buf == '-') 1268 return "*"; 1269 1270 return buf; 1271 } 1272 #endif /* CONFIG_AX25 */ 1273 1274 #define HBUFFERLEN 30 1275 1276 static void arp_format_neigh_entry(struct seq_file *seq, 1277 struct neighbour *n) 1278 { 1279 char hbuffer[HBUFFERLEN]; 1280 int k, j; 1281 char tbuf[16]; 1282 struct net_device *dev = n->dev; 1283 int hatype = dev->type; 1284 1285 read_lock(&n->lock); 1286 /* Convert hardware address to XX:XX:XX:XX ... form. */ 1287 #if IS_ENABLED(CONFIG_AX25) 1288 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM) 1289 ax2asc2((ax25_address *)n->ha, hbuffer); 1290 else { 1291 #endif 1292 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) { 1293 hbuffer[k++] = hex_asc_hi(n->ha[j]); 1294 hbuffer[k++] = hex_asc_lo(n->ha[j]); 1295 hbuffer[k++] = ':'; 1296 } 1297 if (k != 0) 1298 --k; 1299 hbuffer[k] = 0; 1300 #if IS_ENABLED(CONFIG_AX25) 1301 } 1302 #endif 1303 sprintf(tbuf, "%pI4", n->primary_key); 1304 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n", 1305 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name); 1306 read_unlock(&n->lock); 1307 } 1308 1309 static void arp_format_pneigh_entry(struct seq_file *seq, 1310 struct pneigh_entry *n) 1311 { 1312 struct net_device *dev = n->dev; 1313 int hatype = dev ? dev->type : 0; 1314 char tbuf[16]; 1315 1316 sprintf(tbuf, "%pI4", n->key); 1317 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n", 1318 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00", 1319 dev ? dev->name : "*"); 1320 } 1321 1322 static int arp_seq_show(struct seq_file *seq, void *v) 1323 { 1324 if (v == SEQ_START_TOKEN) { 1325 seq_puts(seq, "IP address HW type Flags " 1326 "HW address Mask Device\n"); 1327 } else { 1328 struct neigh_seq_state *state = seq->private; 1329 1330 if (state->flags & NEIGH_SEQ_IS_PNEIGH) 1331 arp_format_pneigh_entry(seq, v); 1332 else 1333 arp_format_neigh_entry(seq, v); 1334 } 1335 1336 return 0; 1337 } 1338 1339 static void *arp_seq_start(struct seq_file *seq, loff_t *pos) 1340 { 1341 /* Don't want to confuse "arp -a" w/ magic entries, 1342 * so we tell the generic iterator to skip NUD_NOARP. 1343 */ 1344 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP); 1345 } 1346 1347 /* ------------------------------------------------------------------------ */ 1348 1349 static const struct seq_operations arp_seq_ops = { 1350 .start = arp_seq_start, 1351 .next = neigh_seq_next, 1352 .stop = neigh_seq_stop, 1353 .show = arp_seq_show, 1354 }; 1355 1356 static int arp_seq_open(struct inode *inode, struct file *file) 1357 { 1358 return seq_open_net(inode, file, &arp_seq_ops, 1359 sizeof(struct neigh_seq_state)); 1360 } 1361 1362 static const struct file_operations arp_seq_fops = { 1363 .owner = THIS_MODULE, 1364 .open = arp_seq_open, 1365 .read = seq_read, 1366 .llseek = seq_lseek, 1367 .release = seq_release_net, 1368 }; 1369 1370 1371 static int __net_init arp_net_init(struct net *net) 1372 { 1373 if (!proc_create("arp", S_IRUGO, net->proc_net, &arp_seq_fops)) 1374 return -ENOMEM; 1375 return 0; 1376 } 1377 1378 static void __net_exit arp_net_exit(struct net *net) 1379 { 1380 remove_proc_entry("arp", net->proc_net); 1381 } 1382 1383 static struct pernet_operations arp_net_ops = { 1384 .init = arp_net_init, 1385 .exit = arp_net_exit, 1386 }; 1387 1388 static int __init arp_proc_init(void) 1389 { 1390 return register_pernet_subsys(&arp_net_ops); 1391 } 1392 1393 #else /* CONFIG_PROC_FS */ 1394 1395 static int __init arp_proc_init(void) 1396 { 1397 return 0; 1398 } 1399 1400 #endif /* CONFIG_PROC_FS */ 1401