1 /* linux/net/ipv4/arp.c 2 * 3 * Copyright (C) 1994 by Florian La Roche 4 * 5 * This module implements the Address Resolution Protocol ARP (RFC 826), 6 * which is used to convert IP addresses (or in the future maybe other 7 * high-level addresses) into a low-level hardware address (like an Ethernet 8 * address). 9 * 10 * This program is free software; you can redistribute it and/or 11 * modify it under the terms of the GNU General Public License 12 * as published by the Free Software Foundation; either version 13 * 2 of the License, or (at your option) any later version. 14 * 15 * Fixes: 16 * Alan Cox : Removed the Ethernet assumptions in 17 * Florian's code 18 * Alan Cox : Fixed some small errors in the ARP 19 * logic 20 * Alan Cox : Allow >4K in /proc 21 * Alan Cox : Make ARP add its own protocol entry 22 * Ross Martin : Rewrote arp_rcv() and arp_get_info() 23 * Stephen Henson : Add AX25 support to arp_get_info() 24 * Alan Cox : Drop data when a device is downed. 25 * Alan Cox : Use init_timer(). 26 * Alan Cox : Double lock fixes. 27 * Martin Seine : Move the arphdr structure 28 * to if_arp.h for compatibility. 29 * with BSD based programs. 30 * Andrew Tridgell : Added ARP netmask code and 31 * re-arranged proxy handling. 32 * Alan Cox : Changed to use notifiers. 33 * Niibe Yutaka : Reply for this device or proxies only. 34 * Alan Cox : Don't proxy across hardware types! 35 * Jonathan Naylor : Added support for NET/ROM. 36 * Mike Shaver : RFC1122 checks. 37 * Jonathan Naylor : Only lookup the hardware address for 38 * the correct hardware type. 39 * Germano Caronni : Assorted subtle races. 40 * Craig Schlenter : Don't modify permanent entry 41 * during arp_rcv. 42 * Russ Nelson : Tidied up a few bits. 43 * Alexey Kuznetsov: Major changes to caching and behaviour, 44 * eg intelligent arp probing and 45 * generation 46 * of host down events. 47 * Alan Cox : Missing unlock in device events. 48 * Eckes : ARP ioctl control errors. 49 * Alexey Kuznetsov: Arp free fix. 50 * Manuel Rodriguez: Gratuitous ARP. 51 * Jonathan Layes : Added arpd support through kerneld 52 * message queue (960314) 53 * Mike Shaver : /proc/sys/net/ipv4/arp_* support 54 * Mike McLagan : Routing by source 55 * Stuart Cheshire : Metricom and grat arp fixes 56 * *** FOR 2.1 clean this up *** 57 * Lawrence V. Stefani: (08/12/96) Added FDDI support. 58 * Alan Cox : Took the AP1000 nasty FDDI hack and 59 * folded into the mainstream FDDI code. 60 * Ack spit, Linus how did you allow that 61 * one in... 62 * Jes Sorensen : Make FDDI work again in 2.1.x and 63 * clean up the APFDDI & gen. FDDI bits. 64 * Alexey Kuznetsov: new arp state machine; 65 * now it is in net/core/neighbour.c. 66 * Krzysztof Halasa: Added Frame Relay ARP support. 67 * Arnaldo C. Melo : convert /proc/net/arp to seq_file 68 * Shmulik Hen: Split arp_send to arp_create and 69 * arp_xmit so intermediate drivers like 70 * bonding can change the skb before 71 * sending (e.g. insert 8021q tag). 72 * Harald Welte : convert to make use of jenkins hash 73 * Jesper D. Brouer: Proxy ARP PVLAN RFC 3069 support. 74 */ 75 76 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 77 78 #include <linux/module.h> 79 #include <linux/types.h> 80 #include <linux/string.h> 81 #include <linux/kernel.h> 82 #include <linux/capability.h> 83 #include <linux/socket.h> 84 #include <linux/sockios.h> 85 #include <linux/errno.h> 86 #include <linux/in.h> 87 #include <linux/mm.h> 88 #include <linux/inet.h> 89 #include <linux/inetdevice.h> 90 #include <linux/netdevice.h> 91 #include <linux/etherdevice.h> 92 #include <linux/fddidevice.h> 93 #include <linux/if_arp.h> 94 #include <linux/skbuff.h> 95 #include <linux/proc_fs.h> 96 #include <linux/seq_file.h> 97 #include <linux/stat.h> 98 #include <linux/init.h> 99 #include <linux/net.h> 100 #include <linux/rcupdate.h> 101 #include <linux/slab.h> 102 #ifdef CONFIG_SYSCTL 103 #include <linux/sysctl.h> 104 #endif 105 106 #include <net/net_namespace.h> 107 #include <net/ip.h> 108 #include <net/icmp.h> 109 #include <net/route.h> 110 #include <net/protocol.h> 111 #include <net/tcp.h> 112 #include <net/sock.h> 113 #include <net/arp.h> 114 #include <net/ax25.h> 115 #include <net/netrom.h> 116 #include <net/dst_metadata.h> 117 #include <net/ip_tunnels.h> 118 119 #include <linux/uaccess.h> 120 121 #include <linux/netfilter_arp.h> 122 123 /* 124 * Interface to generic neighbour cache. 125 */ 126 static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd); 127 static bool arp_key_eq(const struct neighbour *n, const void *pkey); 128 static int arp_constructor(struct neighbour *neigh); 129 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb); 130 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb); 131 static void parp_redo(struct sk_buff *skb); 132 133 static const struct neigh_ops arp_generic_ops = { 134 .family = AF_INET, 135 .solicit = arp_solicit, 136 .error_report = arp_error_report, 137 .output = neigh_resolve_output, 138 .connected_output = neigh_connected_output, 139 }; 140 141 static const struct neigh_ops arp_hh_ops = { 142 .family = AF_INET, 143 .solicit = arp_solicit, 144 .error_report = arp_error_report, 145 .output = neigh_resolve_output, 146 .connected_output = neigh_resolve_output, 147 }; 148 149 static const struct neigh_ops arp_direct_ops = { 150 .family = AF_INET, 151 .output = neigh_direct_output, 152 .connected_output = neigh_direct_output, 153 }; 154 155 struct neigh_table arp_tbl = { 156 .family = AF_INET, 157 .key_len = 4, 158 .protocol = cpu_to_be16(ETH_P_IP), 159 .hash = arp_hash, 160 .key_eq = arp_key_eq, 161 .constructor = arp_constructor, 162 .proxy_redo = parp_redo, 163 .id = "arp_cache", 164 .parms = { 165 .tbl = &arp_tbl, 166 .reachable_time = 30 * HZ, 167 .data = { 168 [NEIGH_VAR_MCAST_PROBES] = 3, 169 [NEIGH_VAR_UCAST_PROBES] = 3, 170 [NEIGH_VAR_RETRANS_TIME] = 1 * HZ, 171 [NEIGH_VAR_BASE_REACHABLE_TIME] = 30 * HZ, 172 [NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ, 173 [NEIGH_VAR_GC_STALETIME] = 60 * HZ, 174 [NEIGH_VAR_QUEUE_LEN_BYTES] = 64 * 1024, 175 [NEIGH_VAR_PROXY_QLEN] = 64, 176 [NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ, 177 [NEIGH_VAR_PROXY_DELAY] = (8 * HZ) / 10, 178 [NEIGH_VAR_LOCKTIME] = 1 * HZ, 179 }, 180 }, 181 .gc_interval = 30 * HZ, 182 .gc_thresh1 = 128, 183 .gc_thresh2 = 512, 184 .gc_thresh3 = 1024, 185 }; 186 EXPORT_SYMBOL(arp_tbl); 187 188 int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir) 189 { 190 switch (dev->type) { 191 case ARPHRD_ETHER: 192 case ARPHRD_FDDI: 193 case ARPHRD_IEEE802: 194 ip_eth_mc_map(addr, haddr); 195 return 0; 196 case ARPHRD_INFINIBAND: 197 ip_ib_mc_map(addr, dev->broadcast, haddr); 198 return 0; 199 case ARPHRD_IPGRE: 200 ip_ipgre_mc_map(addr, dev->broadcast, haddr); 201 return 0; 202 default: 203 if (dir) { 204 memcpy(haddr, dev->broadcast, dev->addr_len); 205 return 0; 206 } 207 } 208 return -EINVAL; 209 } 210 211 212 static u32 arp_hash(const void *pkey, 213 const struct net_device *dev, 214 __u32 *hash_rnd) 215 { 216 return arp_hashfn(pkey, dev, hash_rnd); 217 } 218 219 static bool arp_key_eq(const struct neighbour *neigh, const void *pkey) 220 { 221 return neigh_key_eq32(neigh, pkey); 222 } 223 224 static int arp_constructor(struct neighbour *neigh) 225 { 226 __be32 addr = *(__be32 *)neigh->primary_key; 227 struct net_device *dev = neigh->dev; 228 struct in_device *in_dev; 229 struct neigh_parms *parms; 230 231 rcu_read_lock(); 232 in_dev = __in_dev_get_rcu(dev); 233 if (!in_dev) { 234 rcu_read_unlock(); 235 return -EINVAL; 236 } 237 238 neigh->type = inet_addr_type_dev_table(dev_net(dev), dev, addr); 239 240 parms = in_dev->arp_parms; 241 __neigh_parms_put(neigh->parms); 242 neigh->parms = neigh_parms_clone(parms); 243 rcu_read_unlock(); 244 245 if (!dev->header_ops) { 246 neigh->nud_state = NUD_NOARP; 247 neigh->ops = &arp_direct_ops; 248 neigh->output = neigh_direct_output; 249 } else { 250 /* Good devices (checked by reading texts, but only Ethernet is 251 tested) 252 253 ARPHRD_ETHER: (ethernet, apfddi) 254 ARPHRD_FDDI: (fddi) 255 ARPHRD_IEEE802: (tr) 256 ARPHRD_METRICOM: (strip) 257 ARPHRD_ARCNET: 258 etc. etc. etc. 259 260 ARPHRD_IPDDP will also work, if author repairs it. 261 I did not it, because this driver does not work even 262 in old paradigm. 263 */ 264 265 if (neigh->type == RTN_MULTICAST) { 266 neigh->nud_state = NUD_NOARP; 267 arp_mc_map(addr, neigh->ha, dev, 1); 268 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) { 269 neigh->nud_state = NUD_NOARP; 270 memcpy(neigh->ha, dev->dev_addr, dev->addr_len); 271 } else if (neigh->type == RTN_BROADCAST || 272 (dev->flags & IFF_POINTOPOINT)) { 273 neigh->nud_state = NUD_NOARP; 274 memcpy(neigh->ha, dev->broadcast, dev->addr_len); 275 } 276 277 if (dev->header_ops->cache) 278 neigh->ops = &arp_hh_ops; 279 else 280 neigh->ops = &arp_generic_ops; 281 282 if (neigh->nud_state & NUD_VALID) 283 neigh->output = neigh->ops->connected_output; 284 else 285 neigh->output = neigh->ops->output; 286 } 287 return 0; 288 } 289 290 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb) 291 { 292 dst_link_failure(skb); 293 kfree_skb(skb); 294 } 295 296 /* Create and send an arp packet. */ 297 static void arp_send_dst(int type, int ptype, __be32 dest_ip, 298 struct net_device *dev, __be32 src_ip, 299 const unsigned char *dest_hw, 300 const unsigned char *src_hw, 301 const unsigned char *target_hw, 302 struct dst_entry *dst) 303 { 304 struct sk_buff *skb; 305 306 /* arp on this interface. */ 307 if (dev->flags & IFF_NOARP) 308 return; 309 310 skb = arp_create(type, ptype, dest_ip, dev, src_ip, 311 dest_hw, src_hw, target_hw); 312 if (!skb) 313 return; 314 315 skb_dst_set(skb, dst_clone(dst)); 316 arp_xmit(skb); 317 } 318 319 void arp_send(int type, int ptype, __be32 dest_ip, 320 struct net_device *dev, __be32 src_ip, 321 const unsigned char *dest_hw, const unsigned char *src_hw, 322 const unsigned char *target_hw) 323 { 324 arp_send_dst(type, ptype, dest_ip, dev, src_ip, dest_hw, src_hw, 325 target_hw, NULL); 326 } 327 EXPORT_SYMBOL(arp_send); 328 329 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb) 330 { 331 __be32 saddr = 0; 332 u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL; 333 struct net_device *dev = neigh->dev; 334 __be32 target = *(__be32 *)neigh->primary_key; 335 int probes = atomic_read(&neigh->probes); 336 struct in_device *in_dev; 337 struct dst_entry *dst = NULL; 338 339 rcu_read_lock(); 340 in_dev = __in_dev_get_rcu(dev); 341 if (!in_dev) { 342 rcu_read_unlock(); 343 return; 344 } 345 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) { 346 default: 347 case 0: /* By default announce any local IP */ 348 if (skb && inet_addr_type_dev_table(dev_net(dev), dev, 349 ip_hdr(skb)->saddr) == RTN_LOCAL) 350 saddr = ip_hdr(skb)->saddr; 351 break; 352 case 1: /* Restrict announcements of saddr in same subnet */ 353 if (!skb) 354 break; 355 saddr = ip_hdr(skb)->saddr; 356 if (inet_addr_type_dev_table(dev_net(dev), dev, 357 saddr) == RTN_LOCAL) { 358 /* saddr should be known to target */ 359 if (inet_addr_onlink(in_dev, target, saddr)) 360 break; 361 } 362 saddr = 0; 363 break; 364 case 2: /* Avoid secondary IPs, get a primary/preferred one */ 365 break; 366 } 367 rcu_read_unlock(); 368 369 if (!saddr) 370 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK); 371 372 probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES); 373 if (probes < 0) { 374 if (!(neigh->nud_state & NUD_VALID)) 375 pr_debug("trying to ucast probe in NUD_INVALID\n"); 376 neigh_ha_snapshot(dst_ha, neigh, dev); 377 dst_hw = dst_ha; 378 } else { 379 probes -= NEIGH_VAR(neigh->parms, APP_PROBES); 380 if (probes < 0) { 381 neigh_app_ns(neigh); 382 return; 383 } 384 } 385 386 if (skb && !(dev->priv_flags & IFF_XMIT_DST_RELEASE)) 387 dst = skb_dst(skb); 388 arp_send_dst(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr, 389 dst_hw, dev->dev_addr, NULL, dst); 390 } 391 392 static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip) 393 { 394 struct net *net = dev_net(in_dev->dev); 395 int scope; 396 397 switch (IN_DEV_ARP_IGNORE(in_dev)) { 398 case 0: /* Reply, the tip is already validated */ 399 return 0; 400 case 1: /* Reply only if tip is configured on the incoming interface */ 401 sip = 0; 402 scope = RT_SCOPE_HOST; 403 break; 404 case 2: /* 405 * Reply only if tip is configured on the incoming interface 406 * and is in same subnet as sip 407 */ 408 scope = RT_SCOPE_HOST; 409 break; 410 case 3: /* Do not reply for scope host addresses */ 411 sip = 0; 412 scope = RT_SCOPE_LINK; 413 in_dev = NULL; 414 break; 415 case 4: /* Reserved */ 416 case 5: 417 case 6: 418 case 7: 419 return 0; 420 case 8: /* Do not reply */ 421 return 1; 422 default: 423 return 0; 424 } 425 return !inet_confirm_addr(net, in_dev, sip, tip, scope); 426 } 427 428 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev) 429 { 430 struct rtable *rt; 431 int flag = 0; 432 /*unsigned long now; */ 433 struct net *net = dev_net(dev); 434 435 rt = ip_route_output(net, sip, tip, 0, 0); 436 if (IS_ERR(rt)) 437 return 1; 438 if (rt->dst.dev != dev) { 439 __NET_INC_STATS(net, LINUX_MIB_ARPFILTER); 440 flag = 1; 441 } 442 ip_rt_put(rt); 443 return flag; 444 } 445 446 /* 447 * Check if we can use proxy ARP for this path 448 */ 449 static inline int arp_fwd_proxy(struct in_device *in_dev, 450 struct net_device *dev, struct rtable *rt) 451 { 452 struct in_device *out_dev; 453 int imi, omi = -1; 454 455 if (rt->dst.dev == dev) 456 return 0; 457 458 if (!IN_DEV_PROXY_ARP(in_dev)) 459 return 0; 460 imi = IN_DEV_MEDIUM_ID(in_dev); 461 if (imi == 0) 462 return 1; 463 if (imi == -1) 464 return 0; 465 466 /* place to check for proxy_arp for routes */ 467 468 out_dev = __in_dev_get_rcu(rt->dst.dev); 469 if (out_dev) 470 omi = IN_DEV_MEDIUM_ID(out_dev); 471 472 return omi != imi && omi != -1; 473 } 474 475 /* 476 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev) 477 * 478 * RFC3069 supports proxy arp replies back to the same interface. This 479 * is done to support (ethernet) switch features, like RFC 3069, where 480 * the individual ports are not allowed to communicate with each 481 * other, BUT they are allowed to talk to the upstream router. As 482 * described in RFC 3069, it is possible to allow these hosts to 483 * communicate through the upstream router, by proxy_arp'ing. 484 * 485 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation" 486 * 487 * This technology is known by different names: 488 * In RFC 3069 it is called VLAN Aggregation. 489 * Cisco and Allied Telesyn call it Private VLAN. 490 * Hewlett-Packard call it Source-Port filtering or port-isolation. 491 * Ericsson call it MAC-Forced Forwarding (RFC Draft). 492 * 493 */ 494 static inline int arp_fwd_pvlan(struct in_device *in_dev, 495 struct net_device *dev, struct rtable *rt, 496 __be32 sip, __be32 tip) 497 { 498 /* Private VLAN is only concerned about the same ethernet segment */ 499 if (rt->dst.dev != dev) 500 return 0; 501 502 /* Don't reply on self probes (often done by windowz boxes)*/ 503 if (sip == tip) 504 return 0; 505 506 if (IN_DEV_PROXY_ARP_PVLAN(in_dev)) 507 return 1; 508 else 509 return 0; 510 } 511 512 /* 513 * Interface to link layer: send routine and receive handler. 514 */ 515 516 /* 517 * Create an arp packet. If dest_hw is not set, we create a broadcast 518 * message. 519 */ 520 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip, 521 struct net_device *dev, __be32 src_ip, 522 const unsigned char *dest_hw, 523 const unsigned char *src_hw, 524 const unsigned char *target_hw) 525 { 526 struct sk_buff *skb; 527 struct arphdr *arp; 528 unsigned char *arp_ptr; 529 int hlen = LL_RESERVED_SPACE(dev); 530 int tlen = dev->needed_tailroom; 531 532 /* 533 * Allocate a buffer 534 */ 535 536 skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC); 537 if (!skb) 538 return NULL; 539 540 skb_reserve(skb, hlen); 541 skb_reset_network_header(skb); 542 arp = (struct arphdr *) skb_put(skb, arp_hdr_len(dev)); 543 skb->dev = dev; 544 skb->protocol = htons(ETH_P_ARP); 545 if (!src_hw) 546 src_hw = dev->dev_addr; 547 if (!dest_hw) 548 dest_hw = dev->broadcast; 549 550 /* 551 * Fill the device header for the ARP frame 552 */ 553 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0) 554 goto out; 555 556 /* 557 * Fill out the arp protocol part. 558 * 559 * The arp hardware type should match the device type, except for FDDI, 560 * which (according to RFC 1390) should always equal 1 (Ethernet). 561 */ 562 /* 563 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the 564 * DIX code for the protocol. Make these device structure fields. 565 */ 566 switch (dev->type) { 567 default: 568 arp->ar_hrd = htons(dev->type); 569 arp->ar_pro = htons(ETH_P_IP); 570 break; 571 572 #if IS_ENABLED(CONFIG_AX25) 573 case ARPHRD_AX25: 574 arp->ar_hrd = htons(ARPHRD_AX25); 575 arp->ar_pro = htons(AX25_P_IP); 576 break; 577 578 #if IS_ENABLED(CONFIG_NETROM) 579 case ARPHRD_NETROM: 580 arp->ar_hrd = htons(ARPHRD_NETROM); 581 arp->ar_pro = htons(AX25_P_IP); 582 break; 583 #endif 584 #endif 585 586 #if IS_ENABLED(CONFIG_FDDI) 587 case ARPHRD_FDDI: 588 arp->ar_hrd = htons(ARPHRD_ETHER); 589 arp->ar_pro = htons(ETH_P_IP); 590 break; 591 #endif 592 } 593 594 arp->ar_hln = dev->addr_len; 595 arp->ar_pln = 4; 596 arp->ar_op = htons(type); 597 598 arp_ptr = (unsigned char *)(arp + 1); 599 600 memcpy(arp_ptr, src_hw, dev->addr_len); 601 arp_ptr += dev->addr_len; 602 memcpy(arp_ptr, &src_ip, 4); 603 arp_ptr += 4; 604 605 switch (dev->type) { 606 #if IS_ENABLED(CONFIG_FIREWIRE_NET) 607 case ARPHRD_IEEE1394: 608 break; 609 #endif 610 default: 611 if (target_hw) 612 memcpy(arp_ptr, target_hw, dev->addr_len); 613 else 614 memset(arp_ptr, 0, dev->addr_len); 615 arp_ptr += dev->addr_len; 616 } 617 memcpy(arp_ptr, &dest_ip, 4); 618 619 return skb; 620 621 out: 622 kfree_skb(skb); 623 return NULL; 624 } 625 EXPORT_SYMBOL(arp_create); 626 627 static int arp_xmit_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 628 { 629 return dev_queue_xmit(skb); 630 } 631 632 /* 633 * Send an arp packet. 634 */ 635 void arp_xmit(struct sk_buff *skb) 636 { 637 /* Send it off, maybe filter it using firewalling first. */ 638 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, 639 dev_net(skb->dev), NULL, skb, NULL, skb->dev, 640 arp_xmit_finish); 641 } 642 EXPORT_SYMBOL(arp_xmit); 643 644 /* 645 * Process an arp request. 646 */ 647 648 static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb) 649 { 650 struct net_device *dev = skb->dev; 651 struct in_device *in_dev = __in_dev_get_rcu(dev); 652 struct arphdr *arp; 653 unsigned char *arp_ptr; 654 struct rtable *rt; 655 unsigned char *sha; 656 __be32 sip, tip; 657 u16 dev_type = dev->type; 658 int addr_type; 659 struct neighbour *n; 660 struct dst_entry *reply_dst = NULL; 661 bool is_garp = false; 662 663 /* arp_rcv below verifies the ARP header and verifies the device 664 * is ARP'able. 665 */ 666 667 if (!in_dev) 668 goto out_free_skb; 669 670 arp = arp_hdr(skb); 671 672 switch (dev_type) { 673 default: 674 if (arp->ar_pro != htons(ETH_P_IP) || 675 htons(dev_type) != arp->ar_hrd) 676 goto out_free_skb; 677 break; 678 case ARPHRD_ETHER: 679 case ARPHRD_FDDI: 680 case ARPHRD_IEEE802: 681 /* 682 * ETHERNET, and Fibre Channel (which are IEEE 802 683 * devices, according to RFC 2625) devices will accept ARP 684 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2). 685 * This is the case also of FDDI, where the RFC 1390 says that 686 * FDDI devices should accept ARP hardware of (1) Ethernet, 687 * however, to be more robust, we'll accept both 1 (Ethernet) 688 * or 6 (IEEE 802.2) 689 */ 690 if ((arp->ar_hrd != htons(ARPHRD_ETHER) && 691 arp->ar_hrd != htons(ARPHRD_IEEE802)) || 692 arp->ar_pro != htons(ETH_P_IP)) 693 goto out_free_skb; 694 break; 695 case ARPHRD_AX25: 696 if (arp->ar_pro != htons(AX25_P_IP) || 697 arp->ar_hrd != htons(ARPHRD_AX25)) 698 goto out_free_skb; 699 break; 700 case ARPHRD_NETROM: 701 if (arp->ar_pro != htons(AX25_P_IP) || 702 arp->ar_hrd != htons(ARPHRD_NETROM)) 703 goto out_free_skb; 704 break; 705 } 706 707 /* Understand only these message types */ 708 709 if (arp->ar_op != htons(ARPOP_REPLY) && 710 arp->ar_op != htons(ARPOP_REQUEST)) 711 goto out_free_skb; 712 713 /* 714 * Extract fields 715 */ 716 arp_ptr = (unsigned char *)(arp + 1); 717 sha = arp_ptr; 718 arp_ptr += dev->addr_len; 719 memcpy(&sip, arp_ptr, 4); 720 arp_ptr += 4; 721 switch (dev_type) { 722 #if IS_ENABLED(CONFIG_FIREWIRE_NET) 723 case ARPHRD_IEEE1394: 724 break; 725 #endif 726 default: 727 arp_ptr += dev->addr_len; 728 } 729 memcpy(&tip, arp_ptr, 4); 730 /* 731 * Check for bad requests for 127.x.x.x and requests for multicast 732 * addresses. If this is one such, delete it. 733 */ 734 if (ipv4_is_multicast(tip) || 735 (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip))) 736 goto out_free_skb; 737 738 /* 739 * For some 802.11 wireless deployments (and possibly other networks), 740 * there will be an ARP proxy and gratuitous ARP frames are attacks 741 * and thus should not be accepted. 742 */ 743 if (sip == tip && IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP)) 744 goto out_free_skb; 745 746 /* 747 * Special case: We must set Frame Relay source Q.922 address 748 */ 749 if (dev_type == ARPHRD_DLCI) 750 sha = dev->broadcast; 751 752 /* 753 * Process entry. The idea here is we want to send a reply if it is a 754 * request for us or if it is a request for someone else that we hold 755 * a proxy for. We want to add an entry to our cache if it is a reply 756 * to us or if it is a request for our address. 757 * (The assumption for this last is that if someone is requesting our 758 * address, they are probably intending to talk to us, so it saves time 759 * if we cache their address. Their address is also probably not in 760 * our cache, since ours is not in their cache.) 761 * 762 * Putting this another way, we only care about replies if they are to 763 * us, in which case we add them to the cache. For requests, we care 764 * about those for us and those for our proxies. We reply to both, 765 * and in the case of requests for us we add the requester to the arp 766 * cache. 767 */ 768 769 if (arp->ar_op == htons(ARPOP_REQUEST) && skb_metadata_dst(skb)) 770 reply_dst = (struct dst_entry *) 771 iptunnel_metadata_reply(skb_metadata_dst(skb), 772 GFP_ATOMIC); 773 774 /* Special case: IPv4 duplicate address detection packet (RFC2131) */ 775 if (sip == 0) { 776 if (arp->ar_op == htons(ARPOP_REQUEST) && 777 inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL && 778 !arp_ignore(in_dev, sip, tip)) 779 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, 780 sha, dev->dev_addr, sha, reply_dst); 781 goto out_consume_skb; 782 } 783 784 if (arp->ar_op == htons(ARPOP_REQUEST) && 785 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) { 786 787 rt = skb_rtable(skb); 788 addr_type = rt->rt_type; 789 790 if (addr_type == RTN_LOCAL) { 791 int dont_send; 792 793 dont_send = arp_ignore(in_dev, sip, tip); 794 if (!dont_send && IN_DEV_ARPFILTER(in_dev)) 795 dont_send = arp_filter(sip, tip, dev); 796 if (!dont_send) { 797 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 798 if (n) { 799 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, 800 sip, dev, tip, sha, 801 dev->dev_addr, sha, 802 reply_dst); 803 neigh_release(n); 804 } 805 } 806 goto out_consume_skb; 807 } else if (IN_DEV_FORWARD(in_dev)) { 808 if (addr_type == RTN_UNICAST && 809 (arp_fwd_proxy(in_dev, dev, rt) || 810 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) || 811 (rt->dst.dev != dev && 812 pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) { 813 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 814 if (n) 815 neigh_release(n); 816 817 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED || 818 skb->pkt_type == PACKET_HOST || 819 NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) { 820 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, 821 sip, dev, tip, sha, 822 dev->dev_addr, sha, 823 reply_dst); 824 } else { 825 pneigh_enqueue(&arp_tbl, 826 in_dev->arp_parms, skb); 827 goto out_free_dst; 828 } 829 goto out_consume_skb; 830 } 831 } 832 } 833 834 /* Update our ARP tables */ 835 836 n = __neigh_lookup(&arp_tbl, &sip, dev, 0); 837 838 if (IN_DEV_ARP_ACCEPT(in_dev)) { 839 unsigned int addr_type = inet_addr_type_dev_table(net, dev, sip); 840 841 /* Unsolicited ARP is not accepted by default. 842 It is possible, that this option should be enabled for some 843 devices (strip is candidate) 844 */ 845 is_garp = arp->ar_op == htons(ARPOP_REQUEST) && tip == sip && 846 addr_type == RTN_UNICAST; 847 848 if (!n && 849 ((arp->ar_op == htons(ARPOP_REPLY) && 850 addr_type == RTN_UNICAST) || is_garp)) 851 n = __neigh_lookup(&arp_tbl, &sip, dev, 1); 852 } 853 854 if (n) { 855 int state = NUD_REACHABLE; 856 int override; 857 858 /* If several different ARP replies follows back-to-back, 859 use the FIRST one. It is possible, if several proxy 860 agents are active. Taking the first reply prevents 861 arp trashing and chooses the fastest router. 862 */ 863 override = time_after(jiffies, 864 n->updated + 865 NEIGH_VAR(n->parms, LOCKTIME)) || 866 is_garp; 867 868 /* Broadcast replies and request packets 869 do not assert neighbour reachability. 870 */ 871 if (arp->ar_op != htons(ARPOP_REPLY) || 872 skb->pkt_type != PACKET_HOST) 873 state = NUD_STALE; 874 neigh_update(n, sha, state, 875 override ? NEIGH_UPDATE_F_OVERRIDE : 0); 876 neigh_release(n); 877 } 878 879 out_consume_skb: 880 consume_skb(skb); 881 882 out_free_dst: 883 dst_release(reply_dst); 884 return NET_RX_SUCCESS; 885 886 out_free_skb: 887 kfree_skb(skb); 888 return NET_RX_DROP; 889 } 890 891 static void parp_redo(struct sk_buff *skb) 892 { 893 arp_process(dev_net(skb->dev), NULL, skb); 894 } 895 896 897 /* 898 * Receive an arp request from the device layer. 899 */ 900 901 static int arp_rcv(struct sk_buff *skb, struct net_device *dev, 902 struct packet_type *pt, struct net_device *orig_dev) 903 { 904 const struct arphdr *arp; 905 906 /* do not tweak dropwatch on an ARP we will ignore */ 907 if (dev->flags & IFF_NOARP || 908 skb->pkt_type == PACKET_OTHERHOST || 909 skb->pkt_type == PACKET_LOOPBACK) 910 goto consumeskb; 911 912 skb = skb_share_check(skb, GFP_ATOMIC); 913 if (!skb) 914 goto out_of_mem; 915 916 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */ 917 if (!pskb_may_pull(skb, arp_hdr_len(dev))) 918 goto freeskb; 919 920 arp = arp_hdr(skb); 921 if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4) 922 goto freeskb; 923 924 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb)); 925 926 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, 927 dev_net(dev), NULL, skb, dev, NULL, 928 arp_process); 929 930 consumeskb: 931 consume_skb(skb); 932 return NET_RX_SUCCESS; 933 freeskb: 934 kfree_skb(skb); 935 out_of_mem: 936 return NET_RX_DROP; 937 } 938 939 /* 940 * User level interface (ioctl) 941 */ 942 943 /* 944 * Set (create) an ARP cache entry. 945 */ 946 947 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on) 948 { 949 if (!dev) { 950 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on; 951 return 0; 952 } 953 if (__in_dev_get_rtnl(dev)) { 954 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on); 955 return 0; 956 } 957 return -ENXIO; 958 } 959 960 static int arp_req_set_public(struct net *net, struct arpreq *r, 961 struct net_device *dev) 962 { 963 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 964 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 965 966 if (mask && mask != htonl(0xFFFFFFFF)) 967 return -EINVAL; 968 if (!dev && (r->arp_flags & ATF_COM)) { 969 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family, 970 r->arp_ha.sa_data); 971 if (!dev) 972 return -ENODEV; 973 } 974 if (mask) { 975 if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1)) 976 return -ENOBUFS; 977 return 0; 978 } 979 980 return arp_req_set_proxy(net, dev, 1); 981 } 982 983 static int arp_req_set(struct net *net, struct arpreq *r, 984 struct net_device *dev) 985 { 986 __be32 ip; 987 struct neighbour *neigh; 988 int err; 989 990 if (r->arp_flags & ATF_PUBL) 991 return arp_req_set_public(net, r, dev); 992 993 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 994 if (r->arp_flags & ATF_PERM) 995 r->arp_flags |= ATF_COM; 996 if (!dev) { 997 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0); 998 999 if (IS_ERR(rt)) 1000 return PTR_ERR(rt); 1001 dev = rt->dst.dev; 1002 ip_rt_put(rt); 1003 if (!dev) 1004 return -EINVAL; 1005 } 1006 switch (dev->type) { 1007 #if IS_ENABLED(CONFIG_FDDI) 1008 case ARPHRD_FDDI: 1009 /* 1010 * According to RFC 1390, FDDI devices should accept ARP 1011 * hardware types of 1 (Ethernet). However, to be more 1012 * robust, we'll accept hardware types of either 1 (Ethernet) 1013 * or 6 (IEEE 802.2). 1014 */ 1015 if (r->arp_ha.sa_family != ARPHRD_FDDI && 1016 r->arp_ha.sa_family != ARPHRD_ETHER && 1017 r->arp_ha.sa_family != ARPHRD_IEEE802) 1018 return -EINVAL; 1019 break; 1020 #endif 1021 default: 1022 if (r->arp_ha.sa_family != dev->type) 1023 return -EINVAL; 1024 break; 1025 } 1026 1027 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev); 1028 err = PTR_ERR(neigh); 1029 if (!IS_ERR(neigh)) { 1030 unsigned int state = NUD_STALE; 1031 if (r->arp_flags & ATF_PERM) 1032 state = NUD_PERMANENT; 1033 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ? 1034 r->arp_ha.sa_data : NULL, state, 1035 NEIGH_UPDATE_F_OVERRIDE | 1036 NEIGH_UPDATE_F_ADMIN); 1037 neigh_release(neigh); 1038 } 1039 return err; 1040 } 1041 1042 static unsigned int arp_state_to_flags(struct neighbour *neigh) 1043 { 1044 if (neigh->nud_state&NUD_PERMANENT) 1045 return ATF_PERM | ATF_COM; 1046 else if (neigh->nud_state&NUD_VALID) 1047 return ATF_COM; 1048 else 1049 return 0; 1050 } 1051 1052 /* 1053 * Get an ARP cache entry. 1054 */ 1055 1056 static int arp_req_get(struct arpreq *r, struct net_device *dev) 1057 { 1058 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; 1059 struct neighbour *neigh; 1060 int err = -ENXIO; 1061 1062 neigh = neigh_lookup(&arp_tbl, &ip, dev); 1063 if (neigh) { 1064 if (!(neigh->nud_state & NUD_NOARP)) { 1065 read_lock_bh(&neigh->lock); 1066 memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len); 1067 r->arp_flags = arp_state_to_flags(neigh); 1068 read_unlock_bh(&neigh->lock); 1069 r->arp_ha.sa_family = dev->type; 1070 strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev)); 1071 err = 0; 1072 } 1073 neigh_release(neigh); 1074 } 1075 return err; 1076 } 1077 1078 static int arp_invalidate(struct net_device *dev, __be32 ip) 1079 { 1080 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev); 1081 int err = -ENXIO; 1082 1083 if (neigh) { 1084 if (neigh->nud_state & ~NUD_NOARP) 1085 err = neigh_update(neigh, NULL, NUD_FAILED, 1086 NEIGH_UPDATE_F_OVERRIDE| 1087 NEIGH_UPDATE_F_ADMIN); 1088 neigh_release(neigh); 1089 } 1090 1091 return err; 1092 } 1093 1094 static int arp_req_delete_public(struct net *net, struct arpreq *r, 1095 struct net_device *dev) 1096 { 1097 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; 1098 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 1099 1100 if (mask == htonl(0xFFFFFFFF)) 1101 return pneigh_delete(&arp_tbl, net, &ip, dev); 1102 1103 if (mask) 1104 return -EINVAL; 1105 1106 return arp_req_set_proxy(net, dev, 0); 1107 } 1108 1109 static int arp_req_delete(struct net *net, struct arpreq *r, 1110 struct net_device *dev) 1111 { 1112 __be32 ip; 1113 1114 if (r->arp_flags & ATF_PUBL) 1115 return arp_req_delete_public(net, r, dev); 1116 1117 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1118 if (!dev) { 1119 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0); 1120 if (IS_ERR(rt)) 1121 return PTR_ERR(rt); 1122 dev = rt->dst.dev; 1123 ip_rt_put(rt); 1124 if (!dev) 1125 return -EINVAL; 1126 } 1127 return arp_invalidate(dev, ip); 1128 } 1129 1130 /* 1131 * Handle an ARP layer I/O control request. 1132 */ 1133 1134 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg) 1135 { 1136 int err; 1137 struct arpreq r; 1138 struct net_device *dev = NULL; 1139 1140 switch (cmd) { 1141 case SIOCDARP: 1142 case SIOCSARP: 1143 if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) 1144 return -EPERM; 1145 case SIOCGARP: 1146 err = copy_from_user(&r, arg, sizeof(struct arpreq)); 1147 if (err) 1148 return -EFAULT; 1149 break; 1150 default: 1151 return -EINVAL; 1152 } 1153 1154 if (r.arp_pa.sa_family != AF_INET) 1155 return -EPFNOSUPPORT; 1156 1157 if (!(r.arp_flags & ATF_PUBL) && 1158 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB))) 1159 return -EINVAL; 1160 if (!(r.arp_flags & ATF_NETMASK)) 1161 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr = 1162 htonl(0xFFFFFFFFUL); 1163 rtnl_lock(); 1164 if (r.arp_dev[0]) { 1165 err = -ENODEV; 1166 dev = __dev_get_by_name(net, r.arp_dev); 1167 if (!dev) 1168 goto out; 1169 1170 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */ 1171 if (!r.arp_ha.sa_family) 1172 r.arp_ha.sa_family = dev->type; 1173 err = -EINVAL; 1174 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type) 1175 goto out; 1176 } else if (cmd == SIOCGARP) { 1177 err = -ENODEV; 1178 goto out; 1179 } 1180 1181 switch (cmd) { 1182 case SIOCDARP: 1183 err = arp_req_delete(net, &r, dev); 1184 break; 1185 case SIOCSARP: 1186 err = arp_req_set(net, &r, dev); 1187 break; 1188 case SIOCGARP: 1189 err = arp_req_get(&r, dev); 1190 break; 1191 } 1192 out: 1193 rtnl_unlock(); 1194 if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r))) 1195 err = -EFAULT; 1196 return err; 1197 } 1198 1199 static int arp_netdev_event(struct notifier_block *this, unsigned long event, 1200 void *ptr) 1201 { 1202 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 1203 struct netdev_notifier_change_info *change_info; 1204 1205 switch (event) { 1206 case NETDEV_CHANGEADDR: 1207 neigh_changeaddr(&arp_tbl, dev); 1208 rt_cache_flush(dev_net(dev)); 1209 break; 1210 case NETDEV_CHANGE: 1211 change_info = ptr; 1212 if (change_info->flags_changed & IFF_NOARP) 1213 neigh_changeaddr(&arp_tbl, dev); 1214 break; 1215 default: 1216 break; 1217 } 1218 1219 return NOTIFY_DONE; 1220 } 1221 1222 static struct notifier_block arp_netdev_notifier = { 1223 .notifier_call = arp_netdev_event, 1224 }; 1225 1226 /* Note, that it is not on notifier chain. 1227 It is necessary, that this routine was called after route cache will be 1228 flushed. 1229 */ 1230 void arp_ifdown(struct net_device *dev) 1231 { 1232 neigh_ifdown(&arp_tbl, dev); 1233 } 1234 1235 1236 /* 1237 * Called once on startup. 1238 */ 1239 1240 static struct packet_type arp_packet_type __read_mostly = { 1241 .type = cpu_to_be16(ETH_P_ARP), 1242 .func = arp_rcv, 1243 }; 1244 1245 static int arp_proc_init(void); 1246 1247 void __init arp_init(void) 1248 { 1249 neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl); 1250 1251 dev_add_pack(&arp_packet_type); 1252 arp_proc_init(); 1253 #ifdef CONFIG_SYSCTL 1254 neigh_sysctl_register(NULL, &arp_tbl.parms, NULL); 1255 #endif 1256 register_netdevice_notifier(&arp_netdev_notifier); 1257 } 1258 1259 #ifdef CONFIG_PROC_FS 1260 #if IS_ENABLED(CONFIG_AX25) 1261 1262 /* ------------------------------------------------------------------------ */ 1263 /* 1264 * ax25 -> ASCII conversion 1265 */ 1266 static char *ax2asc2(ax25_address *a, char *buf) 1267 { 1268 char c, *s; 1269 int n; 1270 1271 for (n = 0, s = buf; n < 6; n++) { 1272 c = (a->ax25_call[n] >> 1) & 0x7F; 1273 1274 if (c != ' ') 1275 *s++ = c; 1276 } 1277 1278 *s++ = '-'; 1279 n = (a->ax25_call[6] >> 1) & 0x0F; 1280 if (n > 9) { 1281 *s++ = '1'; 1282 n -= 10; 1283 } 1284 1285 *s++ = n + '0'; 1286 *s++ = '\0'; 1287 1288 if (*buf == '\0' || *buf == '-') 1289 return "*"; 1290 1291 return buf; 1292 } 1293 #endif /* CONFIG_AX25 */ 1294 1295 #define HBUFFERLEN 30 1296 1297 static void arp_format_neigh_entry(struct seq_file *seq, 1298 struct neighbour *n) 1299 { 1300 char hbuffer[HBUFFERLEN]; 1301 int k, j; 1302 char tbuf[16]; 1303 struct net_device *dev = n->dev; 1304 int hatype = dev->type; 1305 1306 read_lock(&n->lock); 1307 /* Convert hardware address to XX:XX:XX:XX ... form. */ 1308 #if IS_ENABLED(CONFIG_AX25) 1309 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM) 1310 ax2asc2((ax25_address *)n->ha, hbuffer); 1311 else { 1312 #endif 1313 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) { 1314 hbuffer[k++] = hex_asc_hi(n->ha[j]); 1315 hbuffer[k++] = hex_asc_lo(n->ha[j]); 1316 hbuffer[k++] = ':'; 1317 } 1318 if (k != 0) 1319 --k; 1320 hbuffer[k] = 0; 1321 #if IS_ENABLED(CONFIG_AX25) 1322 } 1323 #endif 1324 sprintf(tbuf, "%pI4", n->primary_key); 1325 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n", 1326 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name); 1327 read_unlock(&n->lock); 1328 } 1329 1330 static void arp_format_pneigh_entry(struct seq_file *seq, 1331 struct pneigh_entry *n) 1332 { 1333 struct net_device *dev = n->dev; 1334 int hatype = dev ? dev->type : 0; 1335 char tbuf[16]; 1336 1337 sprintf(tbuf, "%pI4", n->key); 1338 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n", 1339 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00", 1340 dev ? dev->name : "*"); 1341 } 1342 1343 static int arp_seq_show(struct seq_file *seq, void *v) 1344 { 1345 if (v == SEQ_START_TOKEN) { 1346 seq_puts(seq, "IP address HW type Flags " 1347 "HW address Mask Device\n"); 1348 } else { 1349 struct neigh_seq_state *state = seq->private; 1350 1351 if (state->flags & NEIGH_SEQ_IS_PNEIGH) 1352 arp_format_pneigh_entry(seq, v); 1353 else 1354 arp_format_neigh_entry(seq, v); 1355 } 1356 1357 return 0; 1358 } 1359 1360 static void *arp_seq_start(struct seq_file *seq, loff_t *pos) 1361 { 1362 /* Don't want to confuse "arp -a" w/ magic entries, 1363 * so we tell the generic iterator to skip NUD_NOARP. 1364 */ 1365 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP); 1366 } 1367 1368 /* ------------------------------------------------------------------------ */ 1369 1370 static const struct seq_operations arp_seq_ops = { 1371 .start = arp_seq_start, 1372 .next = neigh_seq_next, 1373 .stop = neigh_seq_stop, 1374 .show = arp_seq_show, 1375 }; 1376 1377 static int arp_seq_open(struct inode *inode, struct file *file) 1378 { 1379 return seq_open_net(inode, file, &arp_seq_ops, 1380 sizeof(struct neigh_seq_state)); 1381 } 1382 1383 static const struct file_operations arp_seq_fops = { 1384 .owner = THIS_MODULE, 1385 .open = arp_seq_open, 1386 .read = seq_read, 1387 .llseek = seq_lseek, 1388 .release = seq_release_net, 1389 }; 1390 1391 1392 static int __net_init arp_net_init(struct net *net) 1393 { 1394 if (!proc_create("arp", S_IRUGO, net->proc_net, &arp_seq_fops)) 1395 return -ENOMEM; 1396 return 0; 1397 } 1398 1399 static void __net_exit arp_net_exit(struct net *net) 1400 { 1401 remove_proc_entry("arp", net->proc_net); 1402 } 1403 1404 static struct pernet_operations arp_net_ops = { 1405 .init = arp_net_init, 1406 .exit = arp_net_exit, 1407 }; 1408 1409 static int __init arp_proc_init(void) 1410 { 1411 return register_pernet_subsys(&arp_net_ops); 1412 } 1413 1414 #else /* CONFIG_PROC_FS */ 1415 1416 static int __init arp_proc_init(void) 1417 { 1418 return 0; 1419 } 1420 1421 #endif /* CONFIG_PROC_FS */ 1422