1/* linux/net/ipv4/arp.c 2 * 3 * Copyright (C) 1994 by Florian La Roche 4 * 5 * This module implements the Address Resolution Protocol ARP (RFC 826), 6 * which is used to convert IP addresses (or in the future maybe other 7 * high-level addresses) into a low-level hardware address (like an Ethernet 8 * address). 9 * 10 * This program is free software; you can redistribute it and/or 11 * modify it under the terms of the GNU General Public License 12 * as published by the Free Software Foundation; either version 13 * 2 of the License, or (at your option) any later version. 14 * 15 * Fixes: 16 * Alan Cox : Removed the Ethernet assumptions in 17 * Florian's code 18 * Alan Cox : Fixed some small errors in the ARP 19 * logic 20 * Alan Cox : Allow >4K in /proc 21 * Alan Cox : Make ARP add its own protocol entry 22 * Ross Martin : Rewrote arp_rcv() and arp_get_info() 23 * Stephen Henson : Add AX25 support to arp_get_info() 24 * Alan Cox : Drop data when a device is downed. 25 * Alan Cox : Use init_timer(). 26 * Alan Cox : Double lock fixes. 27 * Martin Seine : Move the arphdr structure 28 * to if_arp.h for compatibility. 29 * with BSD based programs. 30 * Andrew Tridgell : Added ARP netmask code and 31 * re-arranged proxy handling. 32 * Alan Cox : Changed to use notifiers. 33 * Niibe Yutaka : Reply for this device or proxies only. 34 * Alan Cox : Don't proxy across hardware types! 35 * Jonathan Naylor : Added support for NET/ROM. 36 * Mike Shaver : RFC1122 checks. 37 * Jonathan Naylor : Only lookup the hardware address for 38 * the correct hardware type. 39 * Germano Caronni : Assorted subtle races. 40 * Craig Schlenter : Don't modify permanent entry 41 * during arp_rcv. 42 * Russ Nelson : Tidied up a few bits. 43 * Alexey Kuznetsov: Major changes to caching and behaviour, 44 * eg intelligent arp probing and 45 * generation 46 * of host down events. 47 * Alan Cox : Missing unlock in device events. 48 * Eckes : ARP ioctl control errors. 49 * Alexey Kuznetsov: Arp free fix. 50 * Manuel Rodriguez: Gratuitous ARP. 51 * Jonathan Layes : Added arpd support through kerneld 52 * message queue (960314) 53 * Mike Shaver : /proc/sys/net/ipv4/arp_* support 54 * Mike McLagan : Routing by source 55 * Stuart Cheshire : Metricom and grat arp fixes 56 * *** FOR 2.1 clean this up *** 57 * Lawrence V. Stefani: (08/12/96) Added FDDI support. 58 * Alan Cox : Took the AP1000 nasty FDDI hack and 59 * folded into the mainstream FDDI code. 60 * Ack spit, Linus how did you allow that 61 * one in... 62 * Jes Sorensen : Make FDDI work again in 2.1.x and 63 * clean up the APFDDI & gen. FDDI bits. 64 * Alexey Kuznetsov: new arp state machine; 65 * now it is in net/core/neighbour.c. 66 * Krzysztof Halasa: Added Frame Relay ARP support. 67 * Arnaldo C. Melo : convert /proc/net/arp to seq_file 68 * Shmulik Hen: Split arp_send to arp_create and 69 * arp_xmit so intermediate drivers like 70 * bonding can change the skb before 71 * sending (e.g. insert 8021q tag). 72 * Harald Welte : convert to make use of jenkins hash 73 * Jesper D. Brouer: Proxy ARP PVLAN RFC 3069 support. 74 */ 75 76#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 77 78#include <linux/module.h> 79#include <linux/types.h> 80#include <linux/string.h> 81#include <linux/kernel.h> 82#include <linux/capability.h> 83#include <linux/socket.h> 84#include <linux/sockios.h> 85#include <linux/errno.h> 86#include <linux/in.h> 87#include <linux/mm.h> 88#include <linux/inet.h> 89#include <linux/inetdevice.h> 90#include <linux/netdevice.h> 91#include <linux/etherdevice.h> 92#include <linux/fddidevice.h> 93#include <linux/if_arp.h> 94#include <linux/skbuff.h> 95#include <linux/proc_fs.h> 96#include <linux/seq_file.h> 97#include <linux/stat.h> 98#include <linux/init.h> 99#include <linux/net.h> 100#include <linux/rcupdate.h> 101#include <linux/slab.h> 102#ifdef CONFIG_SYSCTL 103#include <linux/sysctl.h> 104#endif 105 106#include <net/net_namespace.h> 107#include <net/ip.h> 108#include <net/icmp.h> 109#include <net/route.h> 110#include <net/protocol.h> 111#include <net/tcp.h> 112#include <net/sock.h> 113#include <net/arp.h> 114#include <net/ax25.h> 115#include <net/netrom.h> 116 117#include <linux/uaccess.h> 118 119#include <linux/netfilter_arp.h> 120 121/* 122 * Interface to generic neighbour cache. 123 */ 124static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd); 125static int arp_constructor(struct neighbour *neigh); 126static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb); 127static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb); 128static void parp_redo(struct sk_buff *skb); 129 130static const struct neigh_ops arp_generic_ops = { 131 .family = AF_INET, 132 .solicit = arp_solicit, 133 .error_report = arp_error_report, 134 .output = neigh_resolve_output, 135 .connected_output = neigh_connected_output, 136}; 137 138static const struct neigh_ops arp_hh_ops = { 139 .family = AF_INET, 140 .solicit = arp_solicit, 141 .error_report = arp_error_report, 142 .output = neigh_resolve_output, 143 .connected_output = neigh_resolve_output, 144}; 145 146static const struct neigh_ops arp_direct_ops = { 147 .family = AF_INET, 148 .output = neigh_direct_output, 149 .connected_output = neigh_direct_output, 150}; 151 152static const struct neigh_ops arp_broken_ops = { 153 .family = AF_INET, 154 .solicit = arp_solicit, 155 .error_report = arp_error_report, 156 .output = neigh_compat_output, 157 .connected_output = neigh_compat_output, 158}; 159 160struct neigh_table arp_tbl = { 161 .family = AF_INET, 162 .key_len = 4, 163 .hash = arp_hash, 164 .constructor = arp_constructor, 165 .proxy_redo = parp_redo, 166 .id = "arp_cache", 167 .parms = { 168 .tbl = &arp_tbl, 169 .reachable_time = 30 * HZ, 170 .data = { 171 [NEIGH_VAR_MCAST_PROBES] = 3, 172 [NEIGH_VAR_UCAST_PROBES] = 3, 173 [NEIGH_VAR_RETRANS_TIME] = 1 * HZ, 174 [NEIGH_VAR_BASE_REACHABLE_TIME] = 30 * HZ, 175 [NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ, 176 [NEIGH_VAR_GC_STALETIME] = 60 * HZ, 177 [NEIGH_VAR_QUEUE_LEN_BYTES] = 64 * 1024, 178 [NEIGH_VAR_PROXY_QLEN] = 64, 179 [NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ, 180 [NEIGH_VAR_PROXY_DELAY] = (8 * HZ) / 10, 181 [NEIGH_VAR_LOCKTIME] = 1 * HZ, 182 }, 183 }, 184 .gc_interval = 30 * HZ, 185 .gc_thresh1 = 128, 186 .gc_thresh2 = 512, 187 .gc_thresh3 = 1024, 188}; 189EXPORT_SYMBOL(arp_tbl); 190 191int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir) 192{ 193 switch (dev->type) { 194 case ARPHRD_ETHER: 195 case ARPHRD_FDDI: 196 case ARPHRD_IEEE802: 197 ip_eth_mc_map(addr, haddr); 198 return 0; 199 case ARPHRD_INFINIBAND: 200 ip_ib_mc_map(addr, dev->broadcast, haddr); 201 return 0; 202 case ARPHRD_IPGRE: 203 ip_ipgre_mc_map(addr, dev->broadcast, haddr); 204 return 0; 205 default: 206 if (dir) { 207 memcpy(haddr, dev->broadcast, dev->addr_len); 208 return 0; 209 } 210 } 211 return -EINVAL; 212} 213 214 215static u32 arp_hash(const void *pkey, 216 const struct net_device *dev, 217 __u32 *hash_rnd) 218{ 219 return arp_hashfn(*(u32 *)pkey, dev, *hash_rnd); 220} 221 222static int arp_constructor(struct neighbour *neigh) 223{ 224 __be32 addr = *(__be32 *)neigh->primary_key; 225 struct net_device *dev = neigh->dev; 226 struct in_device *in_dev; 227 struct neigh_parms *parms; 228 229 rcu_read_lock(); 230 in_dev = __in_dev_get_rcu(dev); 231 if (in_dev == NULL) { 232 rcu_read_unlock(); 233 return -EINVAL; 234 } 235 236 neigh->type = inet_addr_type(dev_net(dev), addr); 237 238 parms = in_dev->arp_parms; 239 __neigh_parms_put(neigh->parms); 240 neigh->parms = neigh_parms_clone(parms); 241 rcu_read_unlock(); 242 243 if (!dev->header_ops) { 244 neigh->nud_state = NUD_NOARP; 245 neigh->ops = &arp_direct_ops; 246 neigh->output = neigh_direct_output; 247 } else { 248 /* Good devices (checked by reading texts, but only Ethernet is 249 tested) 250 251 ARPHRD_ETHER: (ethernet, apfddi) 252 ARPHRD_FDDI: (fddi) 253 ARPHRD_IEEE802: (tr) 254 ARPHRD_METRICOM: (strip) 255 ARPHRD_ARCNET: 256 etc. etc. etc. 257 258 ARPHRD_IPDDP will also work, if author repairs it. 259 I did not it, because this driver does not work even 260 in old paradigm. 261 */ 262 263#if 1 264 /* So... these "amateur" devices are hopeless. 265 The only thing, that I can say now: 266 It is very sad that we need to keep ugly obsolete 267 code to make them happy. 268 269 They should be moved to more reasonable state, now 270 they use rebuild_header INSTEAD OF hard_start_xmit!!! 271 Besides that, they are sort of out of date 272 (a lot of redundant clones/copies, useless in 2.1), 273 I wonder why people believe that they work. 274 */ 275 switch (dev->type) { 276 default: 277 break; 278 case ARPHRD_ROSE: 279#if IS_ENABLED(CONFIG_AX25) 280 case ARPHRD_AX25: 281#if IS_ENABLED(CONFIG_NETROM) 282 case ARPHRD_NETROM: 283#endif 284 neigh->ops = &arp_broken_ops; 285 neigh->output = neigh->ops->output; 286 return 0; 287#else 288 break; 289#endif 290 } 291#endif 292 if (neigh->type == RTN_MULTICAST) { 293 neigh->nud_state = NUD_NOARP; 294 arp_mc_map(addr, neigh->ha, dev, 1); 295 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) { 296 neigh->nud_state = NUD_NOARP; 297 memcpy(neigh->ha, dev->dev_addr, dev->addr_len); 298 } else if (neigh->type == RTN_BROADCAST || 299 (dev->flags & IFF_POINTOPOINT)) { 300 neigh->nud_state = NUD_NOARP; 301 memcpy(neigh->ha, dev->broadcast, dev->addr_len); 302 } 303 304 if (dev->header_ops->cache) 305 neigh->ops = &arp_hh_ops; 306 else 307 neigh->ops = &arp_generic_ops; 308 309 if (neigh->nud_state & NUD_VALID) 310 neigh->output = neigh->ops->connected_output; 311 else 312 neigh->output = neigh->ops->output; 313 } 314 return 0; 315} 316 317static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb) 318{ 319 dst_link_failure(skb); 320 kfree_skb(skb); 321} 322 323static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb) 324{ 325 __be32 saddr = 0; 326 u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL; 327 struct net_device *dev = neigh->dev; 328 __be32 target = *(__be32 *)neigh->primary_key; 329 int probes = atomic_read(&neigh->probes); 330 struct in_device *in_dev; 331 332 rcu_read_lock(); 333 in_dev = __in_dev_get_rcu(dev); 334 if (!in_dev) { 335 rcu_read_unlock(); 336 return; 337 } 338 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) { 339 default: 340 case 0: /* By default announce any local IP */ 341 if (skb && inet_addr_type(dev_net(dev), 342 ip_hdr(skb)->saddr) == RTN_LOCAL) 343 saddr = ip_hdr(skb)->saddr; 344 break; 345 case 1: /* Restrict announcements of saddr in same subnet */ 346 if (!skb) 347 break; 348 saddr = ip_hdr(skb)->saddr; 349 if (inet_addr_type(dev_net(dev), saddr) == RTN_LOCAL) { 350 /* saddr should be known to target */ 351 if (inet_addr_onlink(in_dev, target, saddr)) 352 break; 353 } 354 saddr = 0; 355 break; 356 case 2: /* Avoid secondary IPs, get a primary/preferred one */ 357 break; 358 } 359 rcu_read_unlock(); 360 361 if (!saddr) 362 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK); 363 364 probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES); 365 if (probes < 0) { 366 if (!(neigh->nud_state & NUD_VALID)) 367 pr_debug("trying to ucast probe in NUD_INVALID\n"); 368 neigh_ha_snapshot(dst_ha, neigh, dev); 369 dst_hw = dst_ha; 370 } else { 371 probes -= NEIGH_VAR(neigh->parms, APP_PROBES); 372 if (probes < 0) { 373 neigh_app_ns(neigh); 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 382static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip) 383{ 384 struct net *net = dev_net(in_dev->dev); 385 int scope; 386 387 switch (IN_DEV_ARP_IGNORE(in_dev)) { 388 case 0: /* Reply, the tip is already validated */ 389 return 0; 390 case 1: /* Reply only if tip is configured on the incoming interface */ 391 sip = 0; 392 scope = RT_SCOPE_HOST; 393 break; 394 case 2: /* 395 * Reply only if tip is configured on the incoming interface 396 * and is in same subnet as sip 397 */ 398 scope = RT_SCOPE_HOST; 399 break; 400 case 3: /* Do not reply for scope host addresses */ 401 sip = 0; 402 scope = RT_SCOPE_LINK; 403 in_dev = NULL; 404 break; 405 case 4: /* Reserved */ 406 case 5: 407 case 6: 408 case 7: 409 return 0; 410 case 8: /* Do not reply */ 411 return 1; 412 default: 413 return 0; 414 } 415 return !inet_confirm_addr(net, in_dev, sip, tip, scope); 416} 417 418static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev) 419{ 420 struct rtable *rt; 421 int flag = 0; 422 /*unsigned long now; */ 423 struct net *net = dev_net(dev); 424 425 rt = ip_route_output(net, sip, tip, 0, 0); 426 if (IS_ERR(rt)) 427 return 1; 428 if (rt->dst.dev != dev) { 429 NET_INC_STATS_BH(net, LINUX_MIB_ARPFILTER); 430 flag = 1; 431 } 432 ip_rt_put(rt); 433 return flag; 434} 435 436/* OBSOLETE FUNCTIONS */ 437 438/* 439 * Find an arp mapping in the cache. If not found, post a request. 440 * 441 * It is very UGLY routine: it DOES NOT use skb->dst->neighbour, 442 * even if it exists. It is supposed that skb->dev was mangled 443 * by a virtual device (eql, shaper). Nobody but broken devices 444 * is allowed to use this function, it is scheduled to be removed. --ANK 445 */ 446 447static int arp_set_predefined(int addr_hint, unsigned char *haddr, 448 __be32 paddr, struct net_device *dev) 449{ 450 switch (addr_hint) { 451 case RTN_LOCAL: 452 pr_debug("arp called for own IP address\n"); 453 memcpy(haddr, dev->dev_addr, dev->addr_len); 454 return 1; 455 case RTN_MULTICAST: 456 arp_mc_map(paddr, haddr, dev, 1); 457 return 1; 458 case RTN_BROADCAST: 459 memcpy(haddr, dev->broadcast, dev->addr_len); 460 return 1; 461 } 462 return 0; 463} 464 465 466int arp_find(unsigned char *haddr, struct sk_buff *skb) 467{ 468 struct net_device *dev = skb->dev; 469 __be32 paddr; 470 struct neighbour *n; 471 472 if (!skb_dst(skb)) { 473 pr_debug("arp_find is called with dst==NULL\n"); 474 kfree_skb(skb); 475 return 1; 476 } 477 478 paddr = rt_nexthop(skb_rtable(skb), ip_hdr(skb)->daddr); 479 if (arp_set_predefined(inet_addr_type(dev_net(dev), paddr), haddr, 480 paddr, dev)) 481 return 0; 482 483 n = __neigh_lookup(&arp_tbl, &paddr, dev, 1); 484 485 if (n) { 486 n->used = jiffies; 487 if (n->nud_state & NUD_VALID || neigh_event_send(n, skb) == 0) { 488 neigh_ha_snapshot(haddr, n, dev); 489 neigh_release(n); 490 return 0; 491 } 492 neigh_release(n); 493 } else 494 kfree_skb(skb); 495 return 1; 496} 497EXPORT_SYMBOL(arp_find); 498 499/* END OF OBSOLETE FUNCTIONS */ 500 501/* 502 * Check if we can use proxy ARP for this path 503 */ 504static inline int arp_fwd_proxy(struct in_device *in_dev, 505 struct net_device *dev, struct rtable *rt) 506{ 507 struct in_device *out_dev; 508 int imi, omi = -1; 509 510 if (rt->dst.dev == dev) 511 return 0; 512 513 if (!IN_DEV_PROXY_ARP(in_dev)) 514 return 0; 515 imi = IN_DEV_MEDIUM_ID(in_dev); 516 if (imi == 0) 517 return 1; 518 if (imi == -1) 519 return 0; 520 521 /* place to check for proxy_arp for routes */ 522 523 out_dev = __in_dev_get_rcu(rt->dst.dev); 524 if (out_dev) 525 omi = IN_DEV_MEDIUM_ID(out_dev); 526 527 return omi != imi && omi != -1; 528} 529 530/* 531 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev) 532 * 533 * RFC3069 supports proxy arp replies back to the same interface. This 534 * is done to support (ethernet) switch features, like RFC 3069, where 535 * the individual ports are not allowed to communicate with each 536 * other, BUT they are allowed to talk to the upstream router. As 537 * described in RFC 3069, it is possible to allow these hosts to 538 * communicate through the upstream router, by proxy_arp'ing. 539 * 540 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation" 541 * 542 * This technology is known by different names: 543 * In RFC 3069 it is called VLAN Aggregation. 544 * Cisco and Allied Telesyn call it Private VLAN. 545 * Hewlett-Packard call it Source-Port filtering or port-isolation. 546 * Ericsson call it MAC-Forced Forwarding (RFC Draft). 547 * 548 */ 549static inline int arp_fwd_pvlan(struct in_device *in_dev, 550 struct net_device *dev, struct rtable *rt, 551 __be32 sip, __be32 tip) 552{ 553 /* Private VLAN is only concerned about the same ethernet segment */ 554 if (rt->dst.dev != dev) 555 return 0; 556 557 /* Don't reply on self probes (often done by windowz boxes)*/ 558 if (sip == tip) 559 return 0; 560 561 if (IN_DEV_PROXY_ARP_PVLAN(in_dev)) 562 return 1; 563 else 564 return 0; 565} 566 567/* 568 * Interface to link layer: send routine and receive handler. 569 */ 570 571/* 572 * Create an arp packet. If (dest_hw == NULL), we create a broadcast 573 * message. 574 */ 575struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip, 576 struct net_device *dev, __be32 src_ip, 577 const unsigned char *dest_hw, 578 const unsigned char *src_hw, 579 const unsigned char *target_hw) 580{ 581 struct sk_buff *skb; 582 struct arphdr *arp; 583 unsigned char *arp_ptr; 584 int hlen = LL_RESERVED_SPACE(dev); 585 int tlen = dev->needed_tailroom; 586 587 /* 588 * Allocate a buffer 589 */ 590 591 skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC); 592 if (skb == NULL) 593 return NULL; 594 595 skb_reserve(skb, hlen); 596 skb_reset_network_header(skb); 597 arp = (struct arphdr *) skb_put(skb, arp_hdr_len(dev)); 598 skb->dev = dev; 599 skb->protocol = htons(ETH_P_ARP); 600 if (src_hw == NULL) 601 src_hw = dev->dev_addr; 602 if (dest_hw == NULL) 603 dest_hw = dev->broadcast; 604 605 /* 606 * Fill the device header for the ARP frame 607 */ 608 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0) 609 goto out; 610 611 /* 612 * Fill out the arp protocol part. 613 * 614 * The arp hardware type should match the device type, except for FDDI, 615 * which (according to RFC 1390) should always equal 1 (Ethernet). 616 */ 617 /* 618 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the 619 * DIX code for the protocol. Make these device structure fields. 620 */ 621 switch (dev->type) { 622 default: 623 arp->ar_hrd = htons(dev->type); 624 arp->ar_pro = htons(ETH_P_IP); 625 break; 626 627#if IS_ENABLED(CONFIG_AX25) 628 case ARPHRD_AX25: 629 arp->ar_hrd = htons(ARPHRD_AX25); 630 arp->ar_pro = htons(AX25_P_IP); 631 break; 632 633#if IS_ENABLED(CONFIG_NETROM) 634 case ARPHRD_NETROM: 635 arp->ar_hrd = htons(ARPHRD_NETROM); 636 arp->ar_pro = htons(AX25_P_IP); 637 break; 638#endif 639#endif 640 641#if IS_ENABLED(CONFIG_FDDI) 642 case ARPHRD_FDDI: 643 arp->ar_hrd = htons(ARPHRD_ETHER); 644 arp->ar_pro = htons(ETH_P_IP); 645 break; 646#endif 647 } 648 649 arp->ar_hln = dev->addr_len; 650 arp->ar_pln = 4; 651 arp->ar_op = htons(type); 652 653 arp_ptr = (unsigned char *)(arp + 1); 654 655 memcpy(arp_ptr, src_hw, dev->addr_len); 656 arp_ptr += dev->addr_len; 657 memcpy(arp_ptr, &src_ip, 4); 658 arp_ptr += 4; 659 660 switch (dev->type) { 661#if IS_ENABLED(CONFIG_FIREWIRE_NET) 662 case ARPHRD_IEEE1394: 663 break; 664#endif 665 default: 666 if (target_hw != NULL) 667 memcpy(arp_ptr, target_hw, dev->addr_len); 668 else 669 memset(arp_ptr, 0, dev->addr_len); 670 arp_ptr += dev->addr_len; 671 } 672 memcpy(arp_ptr, &dest_ip, 4); 673 674 return skb; 675 676out: 677 kfree_skb(skb); 678 return NULL; 679} 680EXPORT_SYMBOL(arp_create); 681 682/* 683 * Send an arp packet. 684 */ 685void arp_xmit(struct sk_buff *skb) 686{ 687 /* Send it off, maybe filter it using firewalling first. */ 688 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, skb, NULL, skb->dev, dev_queue_xmit); 689} 690EXPORT_SYMBOL(arp_xmit); 691 692/* 693 * Create and send an arp packet. 694 */ 695void arp_send(int type, int ptype, __be32 dest_ip, 696 struct net_device *dev, __be32 src_ip, 697 const unsigned char *dest_hw, const unsigned char *src_hw, 698 const unsigned char *target_hw) 699{ 700 struct sk_buff *skb; 701 702 /* 703 * No arp on this interface. 704 */ 705 706 if (dev->flags&IFF_NOARP) 707 return; 708 709 skb = arp_create(type, ptype, dest_ip, dev, src_ip, 710 dest_hw, src_hw, target_hw); 711 if (skb == NULL) 712 return; 713 714 arp_xmit(skb); 715} 716EXPORT_SYMBOL(arp_send); 717 718/* 719 * Process an arp request. 720 */ 721 722static int arp_process(struct sk_buff *skb) 723{ 724 struct net_device *dev = skb->dev; 725 struct in_device *in_dev = __in_dev_get_rcu(dev); 726 struct arphdr *arp; 727 unsigned char *arp_ptr; 728 struct rtable *rt; 729 unsigned char *sha; 730 __be32 sip, tip; 731 u16 dev_type = dev->type; 732 int addr_type; 733 struct neighbour *n; 734 struct net *net = dev_net(dev); 735 bool is_garp = false; 736 737 /* arp_rcv below verifies the ARP header and verifies the device 738 * is ARP'able. 739 */ 740 741 if (in_dev == NULL) 742 goto out; 743 744 arp = arp_hdr(skb); 745 746 switch (dev_type) { 747 default: 748 if (arp->ar_pro != htons(ETH_P_IP) || 749 htons(dev_type) != arp->ar_hrd) 750 goto out; 751 break; 752 case ARPHRD_ETHER: 753 case ARPHRD_FDDI: 754 case ARPHRD_IEEE802: 755 /* 756 * ETHERNET, and Fibre Channel (which are IEEE 802 757 * devices, according to RFC 2625) devices will accept ARP 758 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2). 759 * This is the case also of FDDI, where the RFC 1390 says that 760 * FDDI devices should accept ARP hardware of (1) Ethernet, 761 * however, to be more robust, we'll accept both 1 (Ethernet) 762 * or 6 (IEEE 802.2) 763 */ 764 if ((arp->ar_hrd != htons(ARPHRD_ETHER) && 765 arp->ar_hrd != htons(ARPHRD_IEEE802)) || 766 arp->ar_pro != htons(ETH_P_IP)) 767 goto out; 768 break; 769 case ARPHRD_AX25: 770 if (arp->ar_pro != htons(AX25_P_IP) || 771 arp->ar_hrd != htons(ARPHRD_AX25)) 772 goto out; 773 break; 774 case ARPHRD_NETROM: 775 if (arp->ar_pro != htons(AX25_P_IP) || 776 arp->ar_hrd != htons(ARPHRD_NETROM)) 777 goto out; 778 break; 779 } 780 781 /* Understand only these message types */ 782 783 if (arp->ar_op != htons(ARPOP_REPLY) && 784 arp->ar_op != htons(ARPOP_REQUEST)) 785 goto out; 786 787/* 788 * Extract fields 789 */ 790 arp_ptr = (unsigned char *)(arp + 1); 791 sha = arp_ptr; 792 arp_ptr += dev->addr_len; 793 memcpy(&sip, arp_ptr, 4); 794 arp_ptr += 4; 795 switch (dev_type) { 796#if IS_ENABLED(CONFIG_FIREWIRE_NET) 797 case ARPHRD_IEEE1394: 798 break; 799#endif 800 default: 801 arp_ptr += dev->addr_len; 802 } 803 memcpy(&tip, arp_ptr, 4); 804/* 805 * Check for bad requests for 127.x.x.x and requests for multicast 806 * addresses. If this is one such, delete it. 807 */ 808 if (ipv4_is_multicast(tip) || 809 (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip))) 810 goto out; 811 812/* 813 * Special case: We must set Frame Relay source Q.922 address 814 */ 815 if (dev_type == ARPHRD_DLCI) 816 sha = dev->broadcast; 817 818/* 819 * Process entry. The idea here is we want to send a reply if it is a 820 * request for us or if it is a request for someone else that we hold 821 * a proxy for. We want to add an entry to our cache if it is a reply 822 * to us or if it is a request for our address. 823 * (The assumption for this last is that if someone is requesting our 824 * address, they are probably intending to talk to us, so it saves time 825 * if we cache their address. Their address is also probably not in 826 * our cache, since ours is not in their cache.) 827 * 828 * Putting this another way, we only care about replies if they are to 829 * us, in which case we add them to the cache. For requests, we care 830 * about those for us and those for our proxies. We reply to both, 831 * and in the case of requests for us we add the requester to the arp 832 * cache. 833 */ 834 835 /* Special case: IPv4 duplicate address detection packet (RFC2131) */ 836 if (sip == 0) { 837 if (arp->ar_op == htons(ARPOP_REQUEST) && 838 inet_addr_type(net, tip) == RTN_LOCAL && 839 !arp_ignore(in_dev, sip, tip)) 840 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, sha, 841 dev->dev_addr, sha); 842 goto out; 843 } 844 845 if (arp->ar_op == htons(ARPOP_REQUEST) && 846 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) { 847 848 rt = skb_rtable(skb); 849 addr_type = rt->rt_type; 850 851 if (addr_type == RTN_LOCAL) { 852 int dont_send; 853 854 dont_send = arp_ignore(in_dev, sip, tip); 855 if (!dont_send && IN_DEV_ARPFILTER(in_dev)) 856 dont_send = arp_filter(sip, tip, dev); 857 if (!dont_send) { 858 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 859 if (n) { 860 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, 861 dev, tip, sha, dev->dev_addr, 862 sha); 863 neigh_release(n); 864 } 865 } 866 goto out; 867 } else if (IN_DEV_FORWARD(in_dev)) { 868 if (addr_type == RTN_UNICAST && 869 (arp_fwd_proxy(in_dev, dev, rt) || 870 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) || 871 (rt->dst.dev != dev && 872 pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) { 873 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 874 if (n) 875 neigh_release(n); 876 877 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED || 878 skb->pkt_type == PACKET_HOST || 879 NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) { 880 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, 881 dev, tip, sha, dev->dev_addr, 882 sha); 883 } else { 884 pneigh_enqueue(&arp_tbl, 885 in_dev->arp_parms, skb); 886 return 0; 887 } 888 goto out; 889 } 890 } 891 } 892 893 /* Update our ARP tables */ 894 895 n = __neigh_lookup(&arp_tbl, &sip, dev, 0); 896 897 if (IN_DEV_ARP_ACCEPT(in_dev)) { 898 /* Unsolicited ARP is not accepted by default. 899 It is possible, that this option should be enabled for some 900 devices (strip is candidate) 901 */ 902 is_garp = arp->ar_op == htons(ARPOP_REQUEST) && tip == sip && 903 inet_addr_type(net, sip) == RTN_UNICAST; 904 905 if (n == NULL && 906 ((arp->ar_op == htons(ARPOP_REPLY) && 907 inet_addr_type(net, sip) == RTN_UNICAST) || is_garp)) 908 n = __neigh_lookup(&arp_tbl, &sip, dev, 1); 909 } 910 911 if (n) { 912 int state = NUD_REACHABLE; 913 int override; 914 915 /* If several different ARP replies follows back-to-back, 916 use the FIRST one. It is possible, if several proxy 917 agents are active. Taking the first reply prevents 918 arp trashing and chooses the fastest router. 919 */ 920 override = time_after(jiffies, 921 n->updated + 922 NEIGH_VAR(n->parms, LOCKTIME)) || 923 is_garp; 924 925 /* Broadcast replies and request packets 926 do not assert neighbour reachability. 927 */ 928 if (arp->ar_op != htons(ARPOP_REPLY) || 929 skb->pkt_type != PACKET_HOST) 930 state = NUD_STALE; 931 neigh_update(n, sha, state, 932 override ? NEIGH_UPDATE_F_OVERRIDE : 0); 933 neigh_release(n); 934 } 935 936out: 937 consume_skb(skb); 938 return 0; 939} 940 941static void parp_redo(struct sk_buff *skb) 942{ 943 arp_process(skb); 944} 945 946 947/* 948 * Receive an arp request from the device layer. 949 */ 950 951static int arp_rcv(struct sk_buff *skb, struct net_device *dev, 952 struct packet_type *pt, struct net_device *orig_dev) 953{ 954 const struct arphdr *arp; 955 956 /* do not tweak dropwatch on an ARP we will ignore */ 957 if (dev->flags & IFF_NOARP || 958 skb->pkt_type == PACKET_OTHERHOST || 959 skb->pkt_type == PACKET_LOOPBACK) 960 goto consumeskb; 961 962 skb = skb_share_check(skb, GFP_ATOMIC); 963 if (!skb) 964 goto out_of_mem; 965 966 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */ 967 if (!pskb_may_pull(skb, arp_hdr_len(dev))) 968 goto freeskb; 969 970 arp = arp_hdr(skb); 971 if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4) 972 goto freeskb; 973 974 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb)); 975 976 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, skb, dev, NULL, arp_process); 977 978consumeskb: 979 consume_skb(skb); 980 return 0; 981freeskb: 982 kfree_skb(skb); 983out_of_mem: 984 return 0; 985} 986 987/* 988 * User level interface (ioctl) 989 */ 990 991/* 992 * Set (create) an ARP cache entry. 993 */ 994 995static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on) 996{ 997 if (dev == NULL) { 998 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on; 999 return 0; 1000 } 1001 if (__in_dev_get_rtnl(dev)) { 1002 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on); 1003 return 0; 1004 } 1005 return -ENXIO; 1006} 1007 1008static int arp_req_set_public(struct net *net, struct arpreq *r, 1009 struct net_device *dev) 1010{ 1011 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1012 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 1013 1014 if (mask && mask != htonl(0xFFFFFFFF)) 1015 return -EINVAL; 1016 if (!dev && (r->arp_flags & ATF_COM)) { 1017 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family, 1018 r->arp_ha.sa_data); 1019 if (!dev) 1020 return -ENODEV; 1021 } 1022 if (mask) { 1023 if (pneigh_lookup(&arp_tbl, net, &ip, dev, 1) == NULL) 1024 return -ENOBUFS; 1025 return 0; 1026 } 1027 1028 return arp_req_set_proxy(net, dev, 1); 1029} 1030 1031static int arp_req_set(struct net *net, struct arpreq *r, 1032 struct net_device *dev) 1033{ 1034 __be32 ip; 1035 struct neighbour *neigh; 1036 int err; 1037 1038 if (r->arp_flags & ATF_PUBL) 1039 return arp_req_set_public(net, r, dev); 1040 1041 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1042 if (r->arp_flags & ATF_PERM) 1043 r->arp_flags |= ATF_COM; 1044 if (dev == NULL) { 1045 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0); 1046 1047 if (IS_ERR(rt)) 1048 return PTR_ERR(rt); 1049 dev = rt->dst.dev; 1050 ip_rt_put(rt); 1051 if (!dev) 1052 return -EINVAL; 1053 } 1054 switch (dev->type) { 1055#if IS_ENABLED(CONFIG_FDDI) 1056 case ARPHRD_FDDI: 1057 /* 1058 * According to RFC 1390, FDDI devices should accept ARP 1059 * hardware types of 1 (Ethernet). However, to be more 1060 * robust, we'll accept hardware types of either 1 (Ethernet) 1061 * or 6 (IEEE 802.2). 1062 */ 1063 if (r->arp_ha.sa_family != ARPHRD_FDDI && 1064 r->arp_ha.sa_family != ARPHRD_ETHER && 1065 r->arp_ha.sa_family != ARPHRD_IEEE802) 1066 return -EINVAL; 1067 break; 1068#endif 1069 default: 1070 if (r->arp_ha.sa_family != dev->type) 1071 return -EINVAL; 1072 break; 1073 } 1074 1075 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev); 1076 err = PTR_ERR(neigh); 1077 if (!IS_ERR(neigh)) { 1078 unsigned int state = NUD_STALE; 1079 if (r->arp_flags & ATF_PERM) 1080 state = NUD_PERMANENT; 1081 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ? 1082 r->arp_ha.sa_data : NULL, state, 1083 NEIGH_UPDATE_F_OVERRIDE | 1084 NEIGH_UPDATE_F_ADMIN); 1085 neigh_release(neigh); 1086 } 1087 return err; 1088} 1089 1090static unsigned int arp_state_to_flags(struct neighbour *neigh) 1091{ 1092 if (neigh->nud_state&NUD_PERMANENT) 1093 return ATF_PERM | ATF_COM; 1094 else if (neigh->nud_state&NUD_VALID) 1095 return ATF_COM; 1096 else 1097 return 0; 1098} 1099 1100/* 1101 * Get an ARP cache entry. 1102 */ 1103 1104static int arp_req_get(struct arpreq *r, struct net_device *dev) 1105{ 1106 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; 1107 struct neighbour *neigh; 1108 int err = -ENXIO; 1109 1110 neigh = neigh_lookup(&arp_tbl, &ip, dev); 1111 if (neigh) { 1112 read_lock_bh(&neigh->lock); 1113 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len); 1114 r->arp_flags = arp_state_to_flags(neigh); 1115 read_unlock_bh(&neigh->lock); 1116 r->arp_ha.sa_family = dev->type; 1117 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev)); 1118 neigh_release(neigh); 1119 err = 0; 1120 } 1121 return err; 1122} 1123 1124static int arp_invalidate(struct net_device *dev, __be32 ip) 1125{ 1126 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev); 1127 int err = -ENXIO; 1128 1129 if (neigh) { 1130 if (neigh->nud_state & ~NUD_NOARP) 1131 err = neigh_update(neigh, NULL, NUD_FAILED, 1132 NEIGH_UPDATE_F_OVERRIDE| 1133 NEIGH_UPDATE_F_ADMIN); 1134 neigh_release(neigh); 1135 } 1136 1137 return err; 1138} 1139 1140static int arp_req_delete_public(struct net *net, struct arpreq *r, 1141 struct net_device *dev) 1142{ 1143 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; 1144 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 1145 1146 if (mask == htonl(0xFFFFFFFF)) 1147 return pneigh_delete(&arp_tbl, net, &ip, dev); 1148 1149 if (mask) 1150 return -EINVAL; 1151 1152 return arp_req_set_proxy(net, dev, 0); 1153} 1154 1155static int arp_req_delete(struct net *net, struct arpreq *r, 1156 struct net_device *dev) 1157{ 1158 __be32 ip; 1159 1160 if (r->arp_flags & ATF_PUBL) 1161 return arp_req_delete_public(net, r, dev); 1162 1163 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1164 if (dev == NULL) { 1165 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0); 1166 if (IS_ERR(rt)) 1167 return PTR_ERR(rt); 1168 dev = rt->dst.dev; 1169 ip_rt_put(rt); 1170 if (!dev) 1171 return -EINVAL; 1172 } 1173 return arp_invalidate(dev, ip); 1174} 1175 1176/* 1177 * Handle an ARP layer I/O control request. 1178 */ 1179 1180int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg) 1181{ 1182 int err; 1183 struct arpreq r; 1184 struct net_device *dev = NULL; 1185 1186 switch (cmd) { 1187 case SIOCDARP: 1188 case SIOCSARP: 1189 if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) 1190 return -EPERM; 1191 case SIOCGARP: 1192 err = copy_from_user(&r, arg, sizeof(struct arpreq)); 1193 if (err) 1194 return -EFAULT; 1195 break; 1196 default: 1197 return -EINVAL; 1198 } 1199 1200 if (r.arp_pa.sa_family != AF_INET) 1201 return -EPFNOSUPPORT; 1202 1203 if (!(r.arp_flags & ATF_PUBL) && 1204 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB))) 1205 return -EINVAL; 1206 if (!(r.arp_flags & ATF_NETMASK)) 1207 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr = 1208 htonl(0xFFFFFFFFUL); 1209 rtnl_lock(); 1210 if (r.arp_dev[0]) { 1211 err = -ENODEV; 1212 dev = __dev_get_by_name(net, r.arp_dev); 1213 if (dev == NULL) 1214 goto out; 1215 1216 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */ 1217 if (!r.arp_ha.sa_family) 1218 r.arp_ha.sa_family = dev->type; 1219 err = -EINVAL; 1220 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type) 1221 goto out; 1222 } else if (cmd == SIOCGARP) { 1223 err = -ENODEV; 1224 goto out; 1225 } 1226 1227 switch (cmd) { 1228 case SIOCDARP: 1229 err = arp_req_delete(net, &r, dev); 1230 break; 1231 case SIOCSARP: 1232 err = arp_req_set(net, &r, dev); 1233 break; 1234 case SIOCGARP: 1235 err = arp_req_get(&r, dev); 1236 break; 1237 } 1238out: 1239 rtnl_unlock(); 1240 if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r))) 1241 err = -EFAULT; 1242 return err; 1243} 1244 1245static int arp_netdev_event(struct notifier_block *this, unsigned long event, 1246 void *ptr) 1247{ 1248 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 1249 struct netdev_notifier_change_info *change_info; 1250 1251 switch (event) { 1252 case NETDEV_CHANGEADDR: 1253 neigh_changeaddr(&arp_tbl, dev); 1254 rt_cache_flush(dev_net(dev)); 1255 break; 1256 case NETDEV_CHANGE: 1257 change_info = ptr; 1258 if (change_info->flags_changed & IFF_NOARP) 1259 neigh_changeaddr(&arp_tbl, dev); 1260 break; 1261 default: 1262 break; 1263 } 1264 1265 return NOTIFY_DONE; 1266} 1267 1268static struct notifier_block arp_netdev_notifier = { 1269 .notifier_call = arp_netdev_event, 1270}; 1271 1272/* Note, that it is not on notifier chain. 1273 It is necessary, that this routine was called after route cache will be 1274 flushed. 1275 */ 1276void arp_ifdown(struct net_device *dev) 1277{ 1278 neigh_ifdown(&arp_tbl, dev); 1279} 1280 1281 1282/* 1283 * Called once on startup. 1284 */ 1285 1286static struct packet_type arp_packet_type __read_mostly = { 1287 .type = cpu_to_be16(ETH_P_ARP), 1288 .func = arp_rcv, 1289}; 1290 1291static int arp_proc_init(void); 1292 1293void __init arp_init(void) 1294{ 1295 neigh_table_init(&arp_tbl); 1296 1297 dev_add_pack(&arp_packet_type); 1298 arp_proc_init(); 1299#ifdef CONFIG_SYSCTL 1300 neigh_sysctl_register(NULL, &arp_tbl.parms, NULL); 1301#endif 1302 register_netdevice_notifier(&arp_netdev_notifier); 1303} 1304 1305#ifdef CONFIG_PROC_FS 1306#if IS_ENABLED(CONFIG_AX25) 1307 1308/* ------------------------------------------------------------------------ */ 1309/* 1310 * ax25 -> ASCII conversion 1311 */ 1312static char *ax2asc2(ax25_address *a, char *buf) 1313{ 1314 char c, *s; 1315 int n; 1316 1317 for (n = 0, s = buf; n < 6; n++) { 1318 c = (a->ax25_call[n] >> 1) & 0x7F; 1319 1320 if (c != ' ') 1321 *s++ = c; 1322 } 1323 1324 *s++ = '-'; 1325 n = (a->ax25_call[6] >> 1) & 0x0F; 1326 if (n > 9) { 1327 *s++ = '1'; 1328 n -= 10; 1329 } 1330 1331 *s++ = n + '0'; 1332 *s++ = '\0'; 1333 1334 if (*buf == '\0' || *buf == '-') 1335 return "*"; 1336 1337 return buf; 1338} 1339#endif /* CONFIG_AX25 */ 1340 1341#define HBUFFERLEN 30 1342 1343static void arp_format_neigh_entry(struct seq_file *seq, 1344 struct neighbour *n) 1345{ 1346 char hbuffer[HBUFFERLEN]; 1347 int k, j; 1348 char tbuf[16]; 1349 struct net_device *dev = n->dev; 1350 int hatype = dev->type; 1351 1352 read_lock(&n->lock); 1353 /* Convert hardware address to XX:XX:XX:XX ... form. */ 1354#if IS_ENABLED(CONFIG_AX25) 1355 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM) 1356 ax2asc2((ax25_address *)n->ha, hbuffer); 1357 else { 1358#endif 1359 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) { 1360 hbuffer[k++] = hex_asc_hi(n->ha[j]); 1361 hbuffer[k++] = hex_asc_lo(n->ha[j]); 1362 hbuffer[k++] = ':'; 1363 } 1364 if (k != 0) 1365 --k; 1366 hbuffer[k] = 0; 1367#if IS_ENABLED(CONFIG_AX25) 1368 } 1369#endif 1370 sprintf(tbuf, "%pI4", n->primary_key); 1371 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n", 1372 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name); 1373 read_unlock(&n->lock); 1374} 1375 1376static void arp_format_pneigh_entry(struct seq_file *seq, 1377 struct pneigh_entry *n) 1378{ 1379 struct net_device *dev = n->dev; 1380 int hatype = dev ? dev->type : 0; 1381 char tbuf[16]; 1382 1383 sprintf(tbuf, "%pI4", n->key); 1384 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n", 1385 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00", 1386 dev ? dev->name : "*"); 1387} 1388 1389static int arp_seq_show(struct seq_file *seq, void *v) 1390{ 1391 if (v == SEQ_START_TOKEN) { 1392 seq_puts(seq, "IP address HW type Flags " 1393 "HW address Mask Device\n"); 1394 } else { 1395 struct neigh_seq_state *state = seq->private; 1396 1397 if (state->flags & NEIGH_SEQ_IS_PNEIGH) 1398 arp_format_pneigh_entry(seq, v); 1399 else 1400 arp_format_neigh_entry(seq, v); 1401 } 1402 1403 return 0; 1404} 1405 1406static void *arp_seq_start(struct seq_file *seq, loff_t *pos) 1407{ 1408 /* Don't want to confuse "arp -a" w/ magic entries, 1409 * so we tell the generic iterator to skip NUD_NOARP. 1410 */ 1411 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP); 1412} 1413 1414/* ------------------------------------------------------------------------ */ 1415 1416static const struct seq_operations arp_seq_ops = { 1417 .start = arp_seq_start, 1418 .next = neigh_seq_next, 1419 .stop = neigh_seq_stop, 1420 .show = arp_seq_show, 1421}; 1422 1423static int arp_seq_open(struct inode *inode, struct file *file) 1424{ 1425 return seq_open_net(inode, file, &arp_seq_ops, 1426 sizeof(struct neigh_seq_state)); 1427} 1428 1429static const struct file_operations arp_seq_fops = { 1430 .owner = THIS_MODULE, 1431 .open = arp_seq_open, 1432 .read = seq_read, 1433 .llseek = seq_lseek, 1434 .release = seq_release_net, 1435}; 1436 1437 1438static int __net_init arp_net_init(struct net *net) 1439{ 1440 if (!proc_create("arp", S_IRUGO, net->proc_net, &arp_seq_fops)) 1441 return -ENOMEM; 1442 return 0; 1443} 1444 1445static void __net_exit arp_net_exit(struct net *net) 1446{ 1447 remove_proc_entry("arp", net->proc_net); 1448} 1449 1450static struct pernet_operations arp_net_ops = { 1451 .init = arp_net_init, 1452 .exit = arp_net_exit, 1453}; 1454 1455static int __init arp_proc_init(void) 1456{ 1457 return register_pernet_subsys(&arp_net_ops); 1458} 1459 1460#else /* CONFIG_PROC_FS */ 1461 1462static int __init arp_proc_init(void) 1463{ 1464 return 0; 1465} 1466 1467#endif /* CONFIG_PROC_FS */ 1468