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 #include <linux/module.h> 77 #include <linux/types.h> 78 #include <linux/string.h> 79 #include <linux/kernel.h> 80 #include <linux/capability.h> 81 #include <linux/socket.h> 82 #include <linux/sockios.h> 83 #include <linux/errno.h> 84 #include <linux/in.h> 85 #include <linux/mm.h> 86 #include <linux/inet.h> 87 #include <linux/inetdevice.h> 88 #include <linux/netdevice.h> 89 #include <linux/etherdevice.h> 90 #include <linux/fddidevice.h> 91 #include <linux/if_arp.h> 92 #include <linux/trdevice.h> 93 #include <linux/skbuff.h> 94 #include <linux/proc_fs.h> 95 #include <linux/seq_file.h> 96 #include <linux/stat.h> 97 #include <linux/init.h> 98 #include <linux/net.h> 99 #include <linux/rcupdate.h> 100 #include <linux/slab.h> 101 #ifdef CONFIG_SYSCTL 102 #include <linux/sysctl.h> 103 #endif 104 105 #include <net/net_namespace.h> 106 #include <net/ip.h> 107 #include <net/icmp.h> 108 #include <net/route.h> 109 #include <net/protocol.h> 110 #include <net/tcp.h> 111 #include <net/sock.h> 112 #include <net/arp.h> 113 #include <net/ax25.h> 114 #include <net/netrom.h> 115 116 #include <asm/system.h> 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_IEEE802_TR: 198 ip_tr_mc_map(addr, haddr); 199 return 0; 200 case ARPHRD_INFINIBAND: 201 ip_ib_mc_map(addr, dev->broadcast, haddr); 202 return 0; 203 case ARPHRD_IPGRE: 204 ip_ipgre_mc_map(addr, dev->broadcast, haddr); 205 return 0; 206 default: 207 if (dir) { 208 memcpy(haddr, dev->broadcast, dev->addr_len); 209 return 0; 210 } 211 } 212 return -EINVAL; 213 } 214 215 216 static u32 arp_hash(const void *pkey, 217 const struct net_device *dev, 218 __u32 *hash_rnd) 219 { 220 return arp_hashfn(*(u32 *)pkey, dev, *hash_rnd); 221 } 222 223 static int arp_constructor(struct neighbour *neigh) 224 { 225 __be32 addr = *(__be32 *)neigh->primary_key; 226 struct net_device *dev = neigh->dev; 227 struct in_device *in_dev; 228 struct neigh_parms *parms; 229 230 rcu_read_lock(); 231 in_dev = __in_dev_get_rcu(dev); 232 if (in_dev == NULL) { 233 rcu_read_unlock(); 234 return -EINVAL; 235 } 236 237 neigh->type = inet_addr_type(dev_net(dev), addr); 238 239 parms = in_dev->arp_parms; 240 __neigh_parms_put(neigh->parms); 241 neigh->parms = neigh_parms_clone(parms); 242 rcu_read_unlock(); 243 244 if (!dev->header_ops) { 245 neigh->nud_state = NUD_NOARP; 246 neigh->ops = &arp_direct_ops; 247 neigh->output = neigh_direct_output; 248 } else { 249 /* Good devices (checked by reading texts, but only Ethernet is 250 tested) 251 252 ARPHRD_ETHER: (ethernet, apfddi) 253 ARPHRD_FDDI: (fddi) 254 ARPHRD_IEEE802: (tr) 255 ARPHRD_METRICOM: (strip) 256 ARPHRD_ARCNET: 257 etc. etc. etc. 258 259 ARPHRD_IPDDP will also work, if author repairs it. 260 I did not it, because this driver does not work even 261 in old paradigm. 262 */ 263 264 #if 1 265 /* So... these "amateur" devices are hopeless. 266 The only thing, that I can say now: 267 It is very sad that we need to keep ugly obsolete 268 code to make them happy. 269 270 They should be moved to more reasonable state, now 271 they use rebuild_header INSTEAD OF hard_start_xmit!!! 272 Besides that, they are sort of out of date 273 (a lot of redundant clones/copies, useless in 2.1), 274 I wonder why people believe that they work. 275 */ 276 switch (dev->type) { 277 default: 278 break; 279 case ARPHRD_ROSE: 280 #if IS_ENABLED(CONFIG_AX25) 281 case ARPHRD_AX25: 282 #if IS_ENABLED(CONFIG_NETROM) 283 case ARPHRD_NETROM: 284 #endif 285 neigh->ops = &arp_broken_ops; 286 neigh->output = neigh->ops->output; 287 return 0; 288 #else 289 break; 290 #endif 291 } 292 #endif 293 if (neigh->type == RTN_MULTICAST) { 294 neigh->nud_state = NUD_NOARP; 295 arp_mc_map(addr, neigh->ha, dev, 1); 296 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) { 297 neigh->nud_state = NUD_NOARP; 298 memcpy(neigh->ha, dev->dev_addr, dev->addr_len); 299 } else if (neigh->type == RTN_BROADCAST || 300 (dev->flags & IFF_POINTOPOINT)) { 301 neigh->nud_state = NUD_NOARP; 302 memcpy(neigh->ha, dev->broadcast, dev->addr_len); 303 } 304 305 if (dev->header_ops->cache) 306 neigh->ops = &arp_hh_ops; 307 else 308 neigh->ops = &arp_generic_ops; 309 310 if (neigh->nud_state & NUD_VALID) 311 neigh->output = neigh->ops->connected_output; 312 else 313 neigh->output = neigh->ops->output; 314 } 315 return 0; 316 } 317 318 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb) 319 { 320 dst_link_failure(skb); 321 kfree_skb(skb); 322 } 323 324 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb) 325 { 326 __be32 saddr = 0; 327 u8 *dst_ha = NULL; 328 struct net_device *dev = neigh->dev; 329 __be32 target = *(__be32 *)neigh->primary_key; 330 int probes = atomic_read(&neigh->probes); 331 struct in_device *in_dev; 332 333 rcu_read_lock(); 334 in_dev = __in_dev_get_rcu(dev); 335 if (!in_dev) { 336 rcu_read_unlock(); 337 return; 338 } 339 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) { 340 default: 341 case 0: /* By default announce any local IP */ 342 if (skb && inet_addr_type(dev_net(dev), 343 ip_hdr(skb)->saddr) == RTN_LOCAL) 344 saddr = ip_hdr(skb)->saddr; 345 break; 346 case 1: /* Restrict announcements of saddr in same subnet */ 347 if (!skb) 348 break; 349 saddr = ip_hdr(skb)->saddr; 350 if (inet_addr_type(dev_net(dev), saddr) == RTN_LOCAL) { 351 /* saddr should be known to target */ 352 if (inet_addr_onlink(in_dev, target, saddr)) 353 break; 354 } 355 saddr = 0; 356 break; 357 case 2: /* Avoid secondary IPs, get a primary/preferred one */ 358 break; 359 } 360 rcu_read_unlock(); 361 362 if (!saddr) 363 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK); 364 365 probes -= neigh->parms->ucast_probes; 366 if (probes < 0) { 367 if (!(neigh->nud_state & NUD_VALID)) 368 printk(KERN_DEBUG 369 "trying to ucast probe in NUD_INVALID\n"); 370 dst_ha = neigh->ha; 371 read_lock_bh(&neigh->lock); 372 } else { 373 probes -= neigh->parms->app_probes; 374 if (probes < 0) { 375 #ifdef CONFIG_ARPD 376 neigh_app_ns(neigh); 377 #endif 378 return; 379 } 380 } 381 382 arp_send(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr, 383 dst_ha, dev->dev_addr, NULL); 384 if (dst_ha) 385 read_unlock_bh(&neigh->lock); 386 } 387 388 static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip) 389 { 390 int scope; 391 392 switch (IN_DEV_ARP_IGNORE(in_dev)) { 393 case 0: /* Reply, the tip is already validated */ 394 return 0; 395 case 1: /* Reply only if tip is configured on the incoming interface */ 396 sip = 0; 397 scope = RT_SCOPE_HOST; 398 break; 399 case 2: /* 400 * Reply only if tip is configured on the incoming interface 401 * and is in same subnet as sip 402 */ 403 scope = RT_SCOPE_HOST; 404 break; 405 case 3: /* Do not reply for scope host addresses */ 406 sip = 0; 407 scope = RT_SCOPE_LINK; 408 break; 409 case 4: /* Reserved */ 410 case 5: 411 case 6: 412 case 7: 413 return 0; 414 case 8: /* Do not reply */ 415 return 1; 416 default: 417 return 0; 418 } 419 return !inet_confirm_addr(in_dev, sip, tip, scope); 420 } 421 422 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev) 423 { 424 struct rtable *rt; 425 int flag = 0; 426 /*unsigned long now; */ 427 struct net *net = dev_net(dev); 428 429 rt = ip_route_output(net, sip, tip, 0, 0); 430 if (IS_ERR(rt)) 431 return 1; 432 if (rt->dst.dev != dev) { 433 NET_INC_STATS_BH(net, LINUX_MIB_ARPFILTER); 434 flag = 1; 435 } 436 ip_rt_put(rt); 437 return flag; 438 } 439 440 /* OBSOLETE FUNCTIONS */ 441 442 /* 443 * Find an arp mapping in the cache. If not found, post a request. 444 * 445 * It is very UGLY routine: it DOES NOT use skb->dst->neighbour, 446 * even if it exists. It is supposed that skb->dev was mangled 447 * by a virtual device (eql, shaper). Nobody but broken devices 448 * is allowed to use this function, it is scheduled to be removed. --ANK 449 */ 450 451 static int arp_set_predefined(int addr_hint, unsigned char *haddr, 452 __be32 paddr, struct net_device *dev) 453 { 454 switch (addr_hint) { 455 case RTN_LOCAL: 456 printk(KERN_DEBUG "ARP: arp called for own IP address\n"); 457 memcpy(haddr, dev->dev_addr, dev->addr_len); 458 return 1; 459 case RTN_MULTICAST: 460 arp_mc_map(paddr, haddr, dev, 1); 461 return 1; 462 case RTN_BROADCAST: 463 memcpy(haddr, dev->broadcast, dev->addr_len); 464 return 1; 465 } 466 return 0; 467 } 468 469 470 int arp_find(unsigned char *haddr, struct sk_buff *skb) 471 { 472 struct net_device *dev = skb->dev; 473 __be32 paddr; 474 struct neighbour *n; 475 476 if (!skb_dst(skb)) { 477 printk(KERN_DEBUG "arp_find is called with dst==NULL\n"); 478 kfree_skb(skb); 479 return 1; 480 } 481 482 paddr = skb_rtable(skb)->rt_gateway; 483 484 if (arp_set_predefined(inet_addr_type(dev_net(dev), paddr), haddr, 485 paddr, dev)) 486 return 0; 487 488 n = __neigh_lookup(&arp_tbl, &paddr, dev, 1); 489 490 if (n) { 491 n->used = jiffies; 492 if (n->nud_state & NUD_VALID || neigh_event_send(n, skb) == 0) { 493 neigh_ha_snapshot(haddr, n, dev); 494 neigh_release(n); 495 return 0; 496 } 497 neigh_release(n); 498 } else 499 kfree_skb(skb); 500 return 1; 501 } 502 EXPORT_SYMBOL(arp_find); 503 504 /* END OF OBSOLETE FUNCTIONS */ 505 506 /* 507 * Check if we can use proxy ARP for this path 508 */ 509 static inline int arp_fwd_proxy(struct in_device *in_dev, 510 struct net_device *dev, struct rtable *rt) 511 { 512 struct in_device *out_dev; 513 int imi, omi = -1; 514 515 if (rt->dst.dev == dev) 516 return 0; 517 518 if (!IN_DEV_PROXY_ARP(in_dev)) 519 return 0; 520 imi = IN_DEV_MEDIUM_ID(in_dev); 521 if (imi == 0) 522 return 1; 523 if (imi == -1) 524 return 0; 525 526 /* place to check for proxy_arp for routes */ 527 528 out_dev = __in_dev_get_rcu(rt->dst.dev); 529 if (out_dev) 530 omi = IN_DEV_MEDIUM_ID(out_dev); 531 532 return omi != imi && omi != -1; 533 } 534 535 /* 536 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev) 537 * 538 * RFC3069 supports proxy arp replies back to the same interface. This 539 * is done to support (ethernet) switch features, like RFC 3069, where 540 * the individual ports are not allowed to communicate with each 541 * other, BUT they are allowed to talk to the upstream router. As 542 * described in RFC 3069, it is possible to allow these hosts to 543 * communicate through the upstream router, by proxy_arp'ing. 544 * 545 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation" 546 * 547 * This technology is known by different names: 548 * In RFC 3069 it is called VLAN Aggregation. 549 * Cisco and Allied Telesyn call it Private VLAN. 550 * Hewlett-Packard call it Source-Port filtering or port-isolation. 551 * Ericsson call it MAC-Forced Forwarding (RFC Draft). 552 * 553 */ 554 static inline int arp_fwd_pvlan(struct in_device *in_dev, 555 struct net_device *dev, struct rtable *rt, 556 __be32 sip, __be32 tip) 557 { 558 /* Private VLAN is only concerned about the same ethernet segment */ 559 if (rt->dst.dev != dev) 560 return 0; 561 562 /* Don't reply on self probes (often done by windowz boxes)*/ 563 if (sip == tip) 564 return 0; 565 566 if (IN_DEV_PROXY_ARP_PVLAN(in_dev)) 567 return 1; 568 else 569 return 0; 570 } 571 572 /* 573 * Interface to link layer: send routine and receive handler. 574 */ 575 576 /* 577 * Create an arp packet. If (dest_hw == NULL), we create a broadcast 578 * message. 579 */ 580 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip, 581 struct net_device *dev, __be32 src_ip, 582 const unsigned char *dest_hw, 583 const unsigned char *src_hw, 584 const unsigned char *target_hw) 585 { 586 struct sk_buff *skb; 587 struct arphdr *arp; 588 unsigned char *arp_ptr; 589 int hlen = LL_RESERVED_SPACE(dev); 590 int tlen = dev->needed_tailroom; 591 592 /* 593 * Allocate a buffer 594 */ 595 596 skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC); 597 if (skb == NULL) 598 return NULL; 599 600 skb_reserve(skb, hlen); 601 skb_reset_network_header(skb); 602 arp = (struct arphdr *) skb_put(skb, arp_hdr_len(dev)); 603 skb->dev = dev; 604 skb->protocol = htons(ETH_P_ARP); 605 if (src_hw == NULL) 606 src_hw = dev->dev_addr; 607 if (dest_hw == NULL) 608 dest_hw = dev->broadcast; 609 610 /* 611 * Fill the device header for the ARP frame 612 */ 613 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0) 614 goto out; 615 616 /* 617 * Fill out the arp protocol part. 618 * 619 * The arp hardware type should match the device type, except for FDDI, 620 * which (according to RFC 1390) should always equal 1 (Ethernet). 621 */ 622 /* 623 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the 624 * DIX code for the protocol. Make these device structure fields. 625 */ 626 switch (dev->type) { 627 default: 628 arp->ar_hrd = htons(dev->type); 629 arp->ar_pro = htons(ETH_P_IP); 630 break; 631 632 #if IS_ENABLED(CONFIG_AX25) 633 case ARPHRD_AX25: 634 arp->ar_hrd = htons(ARPHRD_AX25); 635 arp->ar_pro = htons(AX25_P_IP); 636 break; 637 638 #if IS_ENABLED(CONFIG_NETROM) 639 case ARPHRD_NETROM: 640 arp->ar_hrd = htons(ARPHRD_NETROM); 641 arp->ar_pro = htons(AX25_P_IP); 642 break; 643 #endif 644 #endif 645 646 #if IS_ENABLED(CONFIG_FDDI) 647 case ARPHRD_FDDI: 648 arp->ar_hrd = htons(ARPHRD_ETHER); 649 arp->ar_pro = htons(ETH_P_IP); 650 break; 651 #endif 652 #if IS_ENABLED(CONFIG_TR) 653 case ARPHRD_IEEE802_TR: 654 arp->ar_hrd = htons(ARPHRD_IEEE802); 655 arp->ar_pro = htons(ETH_P_IP); 656 break; 657 #endif 658 } 659 660 arp->ar_hln = dev->addr_len; 661 arp->ar_pln = 4; 662 arp->ar_op = htons(type); 663 664 arp_ptr = (unsigned char *)(arp + 1); 665 666 memcpy(arp_ptr, src_hw, dev->addr_len); 667 arp_ptr += dev->addr_len; 668 memcpy(arp_ptr, &src_ip, 4); 669 arp_ptr += 4; 670 if (target_hw != NULL) 671 memcpy(arp_ptr, target_hw, dev->addr_len); 672 else 673 memset(arp_ptr, 0, dev->addr_len); 674 arp_ptr += dev->addr_len; 675 memcpy(arp_ptr, &dest_ip, 4); 676 677 return skb; 678 679 out: 680 kfree_skb(skb); 681 return NULL; 682 } 683 EXPORT_SYMBOL(arp_create); 684 685 /* 686 * Send an arp packet. 687 */ 688 void arp_xmit(struct sk_buff *skb) 689 { 690 /* Send it off, maybe filter it using firewalling first. */ 691 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, skb, NULL, skb->dev, dev_queue_xmit); 692 } 693 EXPORT_SYMBOL(arp_xmit); 694 695 /* 696 * Create and send an arp packet. 697 */ 698 void arp_send(int type, int ptype, __be32 dest_ip, 699 struct net_device *dev, __be32 src_ip, 700 const unsigned char *dest_hw, const unsigned char *src_hw, 701 const unsigned char *target_hw) 702 { 703 struct sk_buff *skb; 704 705 /* 706 * No arp on this interface. 707 */ 708 709 if (dev->flags&IFF_NOARP) 710 return; 711 712 skb = arp_create(type, ptype, dest_ip, dev, src_ip, 713 dest_hw, src_hw, target_hw); 714 if (skb == NULL) 715 return; 716 717 arp_xmit(skb); 718 } 719 EXPORT_SYMBOL(arp_send); 720 721 /* 722 * Process an arp request. 723 */ 724 725 static int arp_process(struct sk_buff *skb) 726 { 727 struct net_device *dev = skb->dev; 728 struct in_device *in_dev = __in_dev_get_rcu(dev); 729 struct arphdr *arp; 730 unsigned char *arp_ptr; 731 struct rtable *rt; 732 unsigned char *sha; 733 __be32 sip, tip; 734 u16 dev_type = dev->type; 735 int addr_type; 736 struct neighbour *n; 737 struct net *net = dev_net(dev); 738 739 /* arp_rcv below verifies the ARP header and verifies the device 740 * is ARP'able. 741 */ 742 743 if (in_dev == NULL) 744 goto out; 745 746 arp = arp_hdr(skb); 747 748 switch (dev_type) { 749 default: 750 if (arp->ar_pro != htons(ETH_P_IP) || 751 htons(dev_type) != arp->ar_hrd) 752 goto out; 753 break; 754 case ARPHRD_ETHER: 755 case ARPHRD_IEEE802_TR: 756 case ARPHRD_FDDI: 757 case ARPHRD_IEEE802: 758 /* 759 * ETHERNET, Token Ring and Fibre Channel (which are IEEE 802 760 * devices, according to RFC 2625) devices will accept ARP 761 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2). 762 * This is the case also of FDDI, where the RFC 1390 says that 763 * FDDI devices should accept ARP hardware of (1) Ethernet, 764 * however, to be more robust, we'll accept both 1 (Ethernet) 765 * or 6 (IEEE 802.2) 766 */ 767 if ((arp->ar_hrd != htons(ARPHRD_ETHER) && 768 arp->ar_hrd != htons(ARPHRD_IEEE802)) || 769 arp->ar_pro != htons(ETH_P_IP)) 770 goto out; 771 break; 772 case ARPHRD_AX25: 773 if (arp->ar_pro != htons(AX25_P_IP) || 774 arp->ar_hrd != htons(ARPHRD_AX25)) 775 goto out; 776 break; 777 case ARPHRD_NETROM: 778 if (arp->ar_pro != htons(AX25_P_IP) || 779 arp->ar_hrd != htons(ARPHRD_NETROM)) 780 goto out; 781 break; 782 } 783 784 /* Understand only these message types */ 785 786 if (arp->ar_op != htons(ARPOP_REPLY) && 787 arp->ar_op != htons(ARPOP_REQUEST)) 788 goto out; 789 790 /* 791 * Extract fields 792 */ 793 arp_ptr = (unsigned char *)(arp + 1); 794 sha = arp_ptr; 795 arp_ptr += dev->addr_len; 796 memcpy(&sip, arp_ptr, 4); 797 arp_ptr += 4; 798 arp_ptr += dev->addr_len; 799 memcpy(&tip, arp_ptr, 4); 800 /* 801 * Check for bad requests for 127.x.x.x and requests for multicast 802 * addresses. If this is one such, delete it. 803 */ 804 if (ipv4_is_loopback(tip) || ipv4_is_multicast(tip)) 805 goto out; 806 807 /* 808 * Special case: We must set Frame Relay source Q.922 address 809 */ 810 if (dev_type == ARPHRD_DLCI) 811 sha = dev->broadcast; 812 813 /* 814 * Process entry. The idea here is we want to send a reply if it is a 815 * request for us or if it is a request for someone else that we hold 816 * a proxy for. We want to add an entry to our cache if it is a reply 817 * to us or if it is a request for our address. 818 * (The assumption for this last is that if someone is requesting our 819 * address, they are probably intending to talk to us, so it saves time 820 * if we cache their address. Their address is also probably not in 821 * our cache, since ours is not in their cache.) 822 * 823 * Putting this another way, we only care about replies if they are to 824 * us, in which case we add them to the cache. For requests, we care 825 * about those for us and those for our proxies. We reply to both, 826 * and in the case of requests for us we add the requester to the arp 827 * cache. 828 */ 829 830 /* Special case: IPv4 duplicate address detection packet (RFC2131) */ 831 if (sip == 0) { 832 if (arp->ar_op == htons(ARPOP_REQUEST) && 833 inet_addr_type(net, tip) == RTN_LOCAL && 834 !arp_ignore(in_dev, sip, tip)) 835 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, sha, 836 dev->dev_addr, sha); 837 goto out; 838 } 839 840 if (arp->ar_op == htons(ARPOP_REQUEST) && 841 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) { 842 843 rt = skb_rtable(skb); 844 addr_type = rt->rt_type; 845 846 if (addr_type == RTN_LOCAL) { 847 int dont_send; 848 849 dont_send = arp_ignore(in_dev, sip, tip); 850 if (!dont_send && IN_DEV_ARPFILTER(in_dev)) 851 dont_send = arp_filter(sip, tip, dev); 852 if (!dont_send) { 853 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 854 if (n) { 855 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, 856 dev, tip, sha, dev->dev_addr, 857 sha); 858 neigh_release(n); 859 } 860 } 861 goto out; 862 } else if (IN_DEV_FORWARD(in_dev)) { 863 if (addr_type == RTN_UNICAST && 864 (arp_fwd_proxy(in_dev, dev, rt) || 865 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) || 866 (rt->dst.dev != dev && 867 pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) { 868 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 869 if (n) 870 neigh_release(n); 871 872 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED || 873 skb->pkt_type == PACKET_HOST || 874 in_dev->arp_parms->proxy_delay == 0) { 875 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, 876 dev, tip, sha, dev->dev_addr, 877 sha); 878 } else { 879 pneigh_enqueue(&arp_tbl, 880 in_dev->arp_parms, skb); 881 return 0; 882 } 883 goto out; 884 } 885 } 886 } 887 888 /* Update our ARP tables */ 889 890 n = __neigh_lookup(&arp_tbl, &sip, dev, 0); 891 892 if (IN_DEV_ARP_ACCEPT(in_dev)) { 893 /* Unsolicited ARP is not accepted by default. 894 It is possible, that this option should be enabled for some 895 devices (strip is candidate) 896 */ 897 if (n == NULL && 898 (arp->ar_op == htons(ARPOP_REPLY) || 899 (arp->ar_op == htons(ARPOP_REQUEST) && tip == sip)) && 900 inet_addr_type(net, sip) == RTN_UNICAST) 901 n = __neigh_lookup(&arp_tbl, &sip, dev, 1); 902 } 903 904 if (n) { 905 int state = NUD_REACHABLE; 906 int override; 907 908 /* If several different ARP replies follows back-to-back, 909 use the FIRST one. It is possible, if several proxy 910 agents are active. Taking the first reply prevents 911 arp trashing and chooses the fastest router. 912 */ 913 override = time_after(jiffies, n->updated + n->parms->locktime); 914 915 /* Broadcast replies and request packets 916 do not assert neighbour reachability. 917 */ 918 if (arp->ar_op != htons(ARPOP_REPLY) || 919 skb->pkt_type != PACKET_HOST) 920 state = NUD_STALE; 921 neigh_update(n, sha, state, 922 override ? NEIGH_UPDATE_F_OVERRIDE : 0); 923 neigh_release(n); 924 } 925 926 out: 927 consume_skb(skb); 928 return 0; 929 } 930 931 static void parp_redo(struct sk_buff *skb) 932 { 933 arp_process(skb); 934 } 935 936 937 /* 938 * Receive an arp request from the device layer. 939 */ 940 941 static int arp_rcv(struct sk_buff *skb, struct net_device *dev, 942 struct packet_type *pt, struct net_device *orig_dev) 943 { 944 struct arphdr *arp; 945 946 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */ 947 if (!pskb_may_pull(skb, arp_hdr_len(dev))) 948 goto freeskb; 949 950 arp = arp_hdr(skb); 951 if (arp->ar_hln != dev->addr_len || 952 dev->flags & IFF_NOARP || 953 skb->pkt_type == PACKET_OTHERHOST || 954 skb->pkt_type == PACKET_LOOPBACK || 955 arp->ar_pln != 4) 956 goto freeskb; 957 958 skb = skb_share_check(skb, GFP_ATOMIC); 959 if (skb == NULL) 960 goto out_of_mem; 961 962 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb)); 963 964 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, skb, dev, NULL, arp_process); 965 966 freeskb: 967 kfree_skb(skb); 968 out_of_mem: 969 return 0; 970 } 971 972 /* 973 * User level interface (ioctl) 974 */ 975 976 /* 977 * Set (create) an ARP cache entry. 978 */ 979 980 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on) 981 { 982 if (dev == NULL) { 983 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on; 984 return 0; 985 } 986 if (__in_dev_get_rtnl(dev)) { 987 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on); 988 return 0; 989 } 990 return -ENXIO; 991 } 992 993 static int arp_req_set_public(struct net *net, struct arpreq *r, 994 struct net_device *dev) 995 { 996 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 997 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 998 999 if (mask && mask != htonl(0xFFFFFFFF)) 1000 return -EINVAL; 1001 if (!dev && (r->arp_flags & ATF_COM)) { 1002 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family, 1003 r->arp_ha.sa_data); 1004 if (!dev) 1005 return -ENODEV; 1006 } 1007 if (mask) { 1008 if (pneigh_lookup(&arp_tbl, net, &ip, dev, 1) == NULL) 1009 return -ENOBUFS; 1010 return 0; 1011 } 1012 1013 return arp_req_set_proxy(net, dev, 1); 1014 } 1015 1016 static int arp_req_set(struct net *net, struct arpreq *r, 1017 struct net_device *dev) 1018 { 1019 __be32 ip; 1020 struct neighbour *neigh; 1021 int err; 1022 1023 if (r->arp_flags & ATF_PUBL) 1024 return arp_req_set_public(net, r, dev); 1025 1026 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1027 if (r->arp_flags & ATF_PERM) 1028 r->arp_flags |= ATF_COM; 1029 if (dev == NULL) { 1030 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0); 1031 1032 if (IS_ERR(rt)) 1033 return PTR_ERR(rt); 1034 dev = rt->dst.dev; 1035 ip_rt_put(rt); 1036 if (!dev) 1037 return -EINVAL; 1038 } 1039 switch (dev->type) { 1040 #if IS_ENABLED(CONFIG_FDDI) 1041 case ARPHRD_FDDI: 1042 /* 1043 * According to RFC 1390, FDDI devices should accept ARP 1044 * hardware types of 1 (Ethernet). However, to be more 1045 * robust, we'll accept hardware types of either 1 (Ethernet) 1046 * or 6 (IEEE 802.2). 1047 */ 1048 if (r->arp_ha.sa_family != ARPHRD_FDDI && 1049 r->arp_ha.sa_family != ARPHRD_ETHER && 1050 r->arp_ha.sa_family != ARPHRD_IEEE802) 1051 return -EINVAL; 1052 break; 1053 #endif 1054 default: 1055 if (r->arp_ha.sa_family != dev->type) 1056 return -EINVAL; 1057 break; 1058 } 1059 1060 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev); 1061 err = PTR_ERR(neigh); 1062 if (!IS_ERR(neigh)) { 1063 unsigned state = NUD_STALE; 1064 if (r->arp_flags & ATF_PERM) 1065 state = NUD_PERMANENT; 1066 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ? 1067 r->arp_ha.sa_data : NULL, state, 1068 NEIGH_UPDATE_F_OVERRIDE | 1069 NEIGH_UPDATE_F_ADMIN); 1070 neigh_release(neigh); 1071 } 1072 return err; 1073 } 1074 1075 static unsigned arp_state_to_flags(struct neighbour *neigh) 1076 { 1077 if (neigh->nud_state&NUD_PERMANENT) 1078 return ATF_PERM | ATF_COM; 1079 else if (neigh->nud_state&NUD_VALID) 1080 return ATF_COM; 1081 else 1082 return 0; 1083 } 1084 1085 /* 1086 * Get an ARP cache entry. 1087 */ 1088 1089 static int arp_req_get(struct arpreq *r, struct net_device *dev) 1090 { 1091 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; 1092 struct neighbour *neigh; 1093 int err = -ENXIO; 1094 1095 neigh = neigh_lookup(&arp_tbl, &ip, dev); 1096 if (neigh) { 1097 read_lock_bh(&neigh->lock); 1098 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len); 1099 r->arp_flags = arp_state_to_flags(neigh); 1100 read_unlock_bh(&neigh->lock); 1101 r->arp_ha.sa_family = dev->type; 1102 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev)); 1103 neigh_release(neigh); 1104 err = 0; 1105 } 1106 return err; 1107 } 1108 1109 int arp_invalidate(struct net_device *dev, __be32 ip) 1110 { 1111 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev); 1112 int err = -ENXIO; 1113 1114 if (neigh) { 1115 if (neigh->nud_state & ~NUD_NOARP) 1116 err = neigh_update(neigh, NULL, NUD_FAILED, 1117 NEIGH_UPDATE_F_OVERRIDE| 1118 NEIGH_UPDATE_F_ADMIN); 1119 neigh_release(neigh); 1120 } 1121 1122 return err; 1123 } 1124 EXPORT_SYMBOL(arp_invalidate); 1125 1126 static int arp_req_delete_public(struct net *net, struct arpreq *r, 1127 struct net_device *dev) 1128 { 1129 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; 1130 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 1131 1132 if (mask == htonl(0xFFFFFFFF)) 1133 return pneigh_delete(&arp_tbl, net, &ip, dev); 1134 1135 if (mask) 1136 return -EINVAL; 1137 1138 return arp_req_set_proxy(net, dev, 0); 1139 } 1140 1141 static int arp_req_delete(struct net *net, struct arpreq *r, 1142 struct net_device *dev) 1143 { 1144 __be32 ip; 1145 1146 if (r->arp_flags & ATF_PUBL) 1147 return arp_req_delete_public(net, r, dev); 1148 1149 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1150 if (dev == NULL) { 1151 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0); 1152 if (IS_ERR(rt)) 1153 return PTR_ERR(rt); 1154 dev = rt->dst.dev; 1155 ip_rt_put(rt); 1156 if (!dev) 1157 return -EINVAL; 1158 } 1159 return arp_invalidate(dev, ip); 1160 } 1161 1162 /* 1163 * Handle an ARP layer I/O control request. 1164 */ 1165 1166 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg) 1167 { 1168 int err; 1169 struct arpreq r; 1170 struct net_device *dev = NULL; 1171 1172 switch (cmd) { 1173 case SIOCDARP: 1174 case SIOCSARP: 1175 if (!capable(CAP_NET_ADMIN)) 1176 return -EPERM; 1177 case SIOCGARP: 1178 err = copy_from_user(&r, arg, sizeof(struct arpreq)); 1179 if (err) 1180 return -EFAULT; 1181 break; 1182 default: 1183 return -EINVAL; 1184 } 1185 1186 if (r.arp_pa.sa_family != AF_INET) 1187 return -EPFNOSUPPORT; 1188 1189 if (!(r.arp_flags & ATF_PUBL) && 1190 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB))) 1191 return -EINVAL; 1192 if (!(r.arp_flags & ATF_NETMASK)) 1193 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr = 1194 htonl(0xFFFFFFFFUL); 1195 rtnl_lock(); 1196 if (r.arp_dev[0]) { 1197 err = -ENODEV; 1198 dev = __dev_get_by_name(net, r.arp_dev); 1199 if (dev == NULL) 1200 goto out; 1201 1202 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */ 1203 if (!r.arp_ha.sa_family) 1204 r.arp_ha.sa_family = dev->type; 1205 err = -EINVAL; 1206 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type) 1207 goto out; 1208 } else if (cmd == SIOCGARP) { 1209 err = -ENODEV; 1210 goto out; 1211 } 1212 1213 switch (cmd) { 1214 case SIOCDARP: 1215 err = arp_req_delete(net, &r, dev); 1216 break; 1217 case SIOCSARP: 1218 err = arp_req_set(net, &r, dev); 1219 break; 1220 case SIOCGARP: 1221 err = arp_req_get(&r, dev); 1222 break; 1223 } 1224 out: 1225 rtnl_unlock(); 1226 if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r))) 1227 err = -EFAULT; 1228 return err; 1229 } 1230 1231 static int arp_netdev_event(struct notifier_block *this, unsigned long event, 1232 void *ptr) 1233 { 1234 struct net_device *dev = ptr; 1235 1236 switch (event) { 1237 case NETDEV_CHANGEADDR: 1238 neigh_changeaddr(&arp_tbl, dev); 1239 rt_cache_flush(dev_net(dev), 0); 1240 break; 1241 default: 1242 break; 1243 } 1244 1245 return NOTIFY_DONE; 1246 } 1247 1248 static struct notifier_block arp_netdev_notifier = { 1249 .notifier_call = arp_netdev_event, 1250 }; 1251 1252 /* Note, that it is not on notifier chain. 1253 It is necessary, that this routine was called after route cache will be 1254 flushed. 1255 */ 1256 void arp_ifdown(struct net_device *dev) 1257 { 1258 neigh_ifdown(&arp_tbl, dev); 1259 } 1260 1261 1262 /* 1263 * Called once on startup. 1264 */ 1265 1266 static struct packet_type arp_packet_type __read_mostly = { 1267 .type = cpu_to_be16(ETH_P_ARP), 1268 .func = arp_rcv, 1269 }; 1270 1271 static int arp_proc_init(void); 1272 1273 void __init arp_init(void) 1274 { 1275 neigh_table_init(&arp_tbl); 1276 1277 dev_add_pack(&arp_packet_type); 1278 arp_proc_init(); 1279 #ifdef CONFIG_SYSCTL 1280 neigh_sysctl_register(NULL, &arp_tbl.parms, "ipv4", NULL); 1281 #endif 1282 register_netdevice_notifier(&arp_netdev_notifier); 1283 } 1284 1285 #ifdef CONFIG_PROC_FS 1286 #if IS_ENABLED(CONFIG_AX25) 1287 1288 /* ------------------------------------------------------------------------ */ 1289 /* 1290 * ax25 -> ASCII conversion 1291 */ 1292 static char *ax2asc2(ax25_address *a, char *buf) 1293 { 1294 char c, *s; 1295 int n; 1296 1297 for (n = 0, s = buf; n < 6; n++) { 1298 c = (a->ax25_call[n] >> 1) & 0x7F; 1299 1300 if (c != ' ') 1301 *s++ = c; 1302 } 1303 1304 *s++ = '-'; 1305 n = (a->ax25_call[6] >> 1) & 0x0F; 1306 if (n > 9) { 1307 *s++ = '1'; 1308 n -= 10; 1309 } 1310 1311 *s++ = n + '0'; 1312 *s++ = '\0'; 1313 1314 if (*buf == '\0' || *buf == '-') 1315 return "*"; 1316 1317 return buf; 1318 } 1319 #endif /* CONFIG_AX25 */ 1320 1321 #define HBUFFERLEN 30 1322 1323 static void arp_format_neigh_entry(struct seq_file *seq, 1324 struct neighbour *n) 1325 { 1326 char hbuffer[HBUFFERLEN]; 1327 int k, j; 1328 char tbuf[16]; 1329 struct net_device *dev = n->dev; 1330 int hatype = dev->type; 1331 1332 read_lock(&n->lock); 1333 /* Convert hardware address to XX:XX:XX:XX ... form. */ 1334 #if IS_ENABLED(CONFIG_AX25) 1335 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM) 1336 ax2asc2((ax25_address *)n->ha, hbuffer); 1337 else { 1338 #endif 1339 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) { 1340 hbuffer[k++] = hex_asc_hi(n->ha[j]); 1341 hbuffer[k++] = hex_asc_lo(n->ha[j]); 1342 hbuffer[k++] = ':'; 1343 } 1344 if (k != 0) 1345 --k; 1346 hbuffer[k] = 0; 1347 #if IS_ENABLED(CONFIG_AX25) 1348 } 1349 #endif 1350 sprintf(tbuf, "%pI4", n->primary_key); 1351 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n", 1352 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name); 1353 read_unlock(&n->lock); 1354 } 1355 1356 static void arp_format_pneigh_entry(struct seq_file *seq, 1357 struct pneigh_entry *n) 1358 { 1359 struct net_device *dev = n->dev; 1360 int hatype = dev ? dev->type : 0; 1361 char tbuf[16]; 1362 1363 sprintf(tbuf, "%pI4", n->key); 1364 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n", 1365 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00", 1366 dev ? dev->name : "*"); 1367 } 1368 1369 static int arp_seq_show(struct seq_file *seq, void *v) 1370 { 1371 if (v == SEQ_START_TOKEN) { 1372 seq_puts(seq, "IP address HW type Flags " 1373 "HW address Mask Device\n"); 1374 } else { 1375 struct neigh_seq_state *state = seq->private; 1376 1377 if (state->flags & NEIGH_SEQ_IS_PNEIGH) 1378 arp_format_pneigh_entry(seq, v); 1379 else 1380 arp_format_neigh_entry(seq, v); 1381 } 1382 1383 return 0; 1384 } 1385 1386 static void *arp_seq_start(struct seq_file *seq, loff_t *pos) 1387 { 1388 /* Don't want to confuse "arp -a" w/ magic entries, 1389 * so we tell the generic iterator to skip NUD_NOARP. 1390 */ 1391 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP); 1392 } 1393 1394 /* ------------------------------------------------------------------------ */ 1395 1396 static const struct seq_operations arp_seq_ops = { 1397 .start = arp_seq_start, 1398 .next = neigh_seq_next, 1399 .stop = neigh_seq_stop, 1400 .show = arp_seq_show, 1401 }; 1402 1403 static int arp_seq_open(struct inode *inode, struct file *file) 1404 { 1405 return seq_open_net(inode, file, &arp_seq_ops, 1406 sizeof(struct neigh_seq_state)); 1407 } 1408 1409 static const struct file_operations arp_seq_fops = { 1410 .owner = THIS_MODULE, 1411 .open = arp_seq_open, 1412 .read = seq_read, 1413 .llseek = seq_lseek, 1414 .release = seq_release_net, 1415 }; 1416 1417 1418 static int __net_init arp_net_init(struct net *net) 1419 { 1420 if (!proc_net_fops_create(net, "arp", S_IRUGO, &arp_seq_fops)) 1421 return -ENOMEM; 1422 return 0; 1423 } 1424 1425 static void __net_exit arp_net_exit(struct net *net) 1426 { 1427 proc_net_remove(net, "arp"); 1428 } 1429 1430 static struct pernet_operations arp_net_ops = { 1431 .init = arp_net_init, 1432 .exit = arp_net_exit, 1433 }; 1434 1435 static int __init arp_proc_init(void) 1436 { 1437 return register_pernet_subsys(&arp_net_ops); 1438 } 1439 1440 #else /* CONFIG_PROC_FS */ 1441 1442 static int __init arp_proc_init(void) 1443 { 1444 return 0; 1445 } 1446 1447 #endif /* CONFIG_PROC_FS */ 1448