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