1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* linux/net/ipv4/arp.c 3 * 4 * Copyright (C) 1994 by Florian La Roche 5 * 6 * This module implements the Address Resolution Protocol ARP (RFC 826), 7 * which is used to convert IP addresses (or in the future maybe other 8 * high-level addresses) into a low-level hardware address (like an Ethernet 9 * address). 10 * 11 * Fixes: 12 * Alan Cox : Removed the Ethernet assumptions in 13 * Florian's code 14 * Alan Cox : Fixed some small errors in the ARP 15 * logic 16 * Alan Cox : Allow >4K in /proc 17 * Alan Cox : Make ARP add its own protocol entry 18 * Ross Martin : Rewrote arp_rcv() and arp_get_info() 19 * Stephen Henson : Add AX25 support to arp_get_info() 20 * Alan Cox : Drop data when a device is downed. 21 * Alan Cox : Use init_timer(). 22 * Alan Cox : Double lock fixes. 23 * Martin Seine : Move the arphdr structure 24 * to if_arp.h for compatibility. 25 * with BSD based programs. 26 * Andrew Tridgell : Added ARP netmask code and 27 * re-arranged proxy handling. 28 * Alan Cox : Changed to use notifiers. 29 * Niibe Yutaka : Reply for this device or proxies only. 30 * Alan Cox : Don't proxy across hardware types! 31 * Jonathan Naylor : Added support for NET/ROM. 32 * Mike Shaver : RFC1122 checks. 33 * Jonathan Naylor : Only lookup the hardware address for 34 * the correct hardware type. 35 * Germano Caronni : Assorted subtle races. 36 * Craig Schlenter : Don't modify permanent entry 37 * during arp_rcv. 38 * Russ Nelson : Tidied up a few bits. 39 * Alexey Kuznetsov: Major changes to caching and behaviour, 40 * eg intelligent arp probing and 41 * generation 42 * of host down events. 43 * Alan Cox : Missing unlock in device events. 44 * Eckes : ARP ioctl control errors. 45 * Alexey Kuznetsov: Arp free fix. 46 * Manuel Rodriguez: Gratuitous ARP. 47 * Jonathan Layes : Added arpd support through kerneld 48 * message queue (960314) 49 * Mike Shaver : /proc/sys/net/ipv4/arp_* support 50 * Mike McLagan : Routing by source 51 * Stuart Cheshire : Metricom and grat arp fixes 52 * *** FOR 2.1 clean this up *** 53 * Lawrence V. Stefani: (08/12/96) Added FDDI support. 54 * Alan Cox : Took the AP1000 nasty FDDI hack and 55 * folded into the mainstream FDDI code. 56 * Ack spit, Linus how did you allow that 57 * one in... 58 * Jes Sorensen : Make FDDI work again in 2.1.x and 59 * clean up the APFDDI & gen. FDDI bits. 60 * Alexey Kuznetsov: new arp state machine; 61 * now it is in net/core/neighbour.c. 62 * Krzysztof Halasa: Added Frame Relay ARP support. 63 * Arnaldo C. Melo : convert /proc/net/arp to seq_file 64 * Shmulik Hen: Split arp_send to arp_create and 65 * arp_xmit so intermediate drivers like 66 * bonding can change the skb before 67 * sending (e.g. insert 8021q tag). 68 * Harald Welte : convert to make use of jenkins hash 69 * Jesper D. Brouer: Proxy ARP PVLAN RFC 3069 support. 70 */ 71 72 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 73 74 #include <linux/module.h> 75 #include <linux/types.h> 76 #include <linux/string.h> 77 #include <linux/kernel.h> 78 #include <linux/capability.h> 79 #include <linux/socket.h> 80 #include <linux/sockios.h> 81 #include <linux/errno.h> 82 #include <linux/in.h> 83 #include <linux/mm.h> 84 #include <linux/inet.h> 85 #include <linux/inetdevice.h> 86 #include <linux/netdevice.h> 87 #include <linux/etherdevice.h> 88 #include <linux/fddidevice.h> 89 #include <linux/if_arp.h> 90 #include <linux/skbuff.h> 91 #include <linux/proc_fs.h> 92 #include <linux/seq_file.h> 93 #include <linux/stat.h> 94 #include <linux/init.h> 95 #include <linux/net.h> 96 #include <linux/rcupdate.h> 97 #include <linux/slab.h> 98 #ifdef CONFIG_SYSCTL 99 #include <linux/sysctl.h> 100 #endif 101 102 #include <net/net_namespace.h> 103 #include <net/ip.h> 104 #include <net/icmp.h> 105 #include <net/route.h> 106 #include <net/protocol.h> 107 #include <net/tcp.h> 108 #include <net/sock.h> 109 #include <net/arp.h> 110 #include <net/ax25.h> 111 #include <net/netrom.h> 112 #include <net/dst_metadata.h> 113 #include <net/ip_tunnels.h> 114 115 #include <linux/uaccess.h> 116 117 #include <linux/netfilter_arp.h> 118 119 /* 120 * Interface to generic neighbour cache. 121 */ 122 static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd); 123 static bool arp_key_eq(const struct neighbour *n, const void *pkey); 124 static int arp_constructor(struct neighbour *neigh); 125 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb); 126 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb); 127 static void parp_redo(struct sk_buff *skb); 128 static int arp_is_multicast(const void *pkey); 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 struct neigh_table arp_tbl = { 153 .family = AF_INET, 154 .key_len = 4, 155 .protocol = cpu_to_be16(ETH_P_IP), 156 .hash = arp_hash, 157 .key_eq = arp_key_eq, 158 .constructor = arp_constructor, 159 .proxy_redo = parp_redo, 160 .is_multicast = arp_is_multicast, 161 .id = "arp_cache", 162 .parms = { 163 .tbl = &arp_tbl, 164 .reachable_time = 30 * HZ, 165 .data = { 166 [NEIGH_VAR_MCAST_PROBES] = 3, 167 [NEIGH_VAR_UCAST_PROBES] = 3, 168 [NEIGH_VAR_RETRANS_TIME] = 1 * HZ, 169 [NEIGH_VAR_BASE_REACHABLE_TIME] = 30 * HZ, 170 [NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ, 171 [NEIGH_VAR_INTERVAL_PROBE_TIME_MS] = 5 * HZ, 172 [NEIGH_VAR_GC_STALETIME] = 60 * HZ, 173 [NEIGH_VAR_QUEUE_LEN_BYTES] = SK_WMEM_MAX, 174 [NEIGH_VAR_PROXY_QLEN] = 64, 175 [NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ, 176 [NEIGH_VAR_PROXY_DELAY] = (8 * HZ) / 10, 177 [NEIGH_VAR_LOCKTIME] = 1 * HZ, 178 }, 179 }, 180 .gc_interval = 30 * HZ, 181 .gc_thresh1 = 128, 182 .gc_thresh2 = 512, 183 .gc_thresh3 = 1024, 184 }; 185 EXPORT_SYMBOL(arp_tbl); 186 187 int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir) 188 { 189 switch (dev->type) { 190 case ARPHRD_ETHER: 191 case ARPHRD_FDDI: 192 case ARPHRD_IEEE802: 193 ip_eth_mc_map(addr, haddr); 194 return 0; 195 case ARPHRD_INFINIBAND: 196 ip_ib_mc_map(addr, dev->broadcast, haddr); 197 return 0; 198 case ARPHRD_IPGRE: 199 ip_ipgre_mc_map(addr, dev->broadcast, haddr); 200 return 0; 201 default: 202 if (dir) { 203 memcpy(haddr, dev->broadcast, dev->addr_len); 204 return 0; 205 } 206 } 207 return -EINVAL; 208 } 209 210 211 static u32 arp_hash(const void *pkey, 212 const struct net_device *dev, 213 __u32 *hash_rnd) 214 { 215 return arp_hashfn(pkey, dev, hash_rnd); 216 } 217 218 static bool arp_key_eq(const struct neighbour *neigh, const void *pkey) 219 { 220 return neigh_key_eq32(neigh, pkey); 221 } 222 223 static int arp_constructor(struct neighbour *neigh) 224 { 225 __be32 addr; 226 struct net_device *dev = neigh->dev; 227 struct in_device *in_dev; 228 struct neigh_parms *parms; 229 u32 inaddr_any = INADDR_ANY; 230 231 if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT)) 232 memcpy(neigh->primary_key, &inaddr_any, arp_tbl.key_len); 233 234 addr = *(__be32 *)neigh->primary_key; 235 rcu_read_lock(); 236 in_dev = __in_dev_get_rcu(dev); 237 if (!in_dev) { 238 rcu_read_unlock(); 239 return -EINVAL; 240 } 241 242 neigh->type = inet_addr_type_dev_table(dev_net(dev), dev, addr); 243 244 parms = in_dev->arp_parms; 245 __neigh_parms_put(neigh->parms); 246 neigh->parms = neigh_parms_clone(parms); 247 rcu_read_unlock(); 248 249 if (!dev->header_ops) { 250 neigh->nud_state = NUD_NOARP; 251 neigh->ops = &arp_direct_ops; 252 neigh->output = neigh_direct_output; 253 } else { 254 /* Good devices (checked by reading texts, but only Ethernet is 255 tested) 256 257 ARPHRD_ETHER: (ethernet, apfddi) 258 ARPHRD_FDDI: (fddi) 259 ARPHRD_IEEE802: (tr) 260 ARPHRD_METRICOM: (strip) 261 ARPHRD_ARCNET: 262 etc. etc. etc. 263 264 ARPHRD_IPDDP will also work, if author repairs it. 265 I did not it, because this driver does not work even 266 in old paradigm. 267 */ 268 269 if (neigh->type == RTN_MULTICAST) { 270 neigh->nud_state = NUD_NOARP; 271 arp_mc_map(addr, neigh->ha, dev, 1); 272 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) { 273 neigh->nud_state = NUD_NOARP; 274 memcpy(neigh->ha, dev->dev_addr, dev->addr_len); 275 } else if (neigh->type == RTN_BROADCAST || 276 (dev->flags & IFF_POINTOPOINT)) { 277 neigh->nud_state = NUD_NOARP; 278 memcpy(neigh->ha, dev->broadcast, dev->addr_len); 279 } 280 281 if (dev->header_ops->cache) 282 neigh->ops = &arp_hh_ops; 283 else 284 neigh->ops = &arp_generic_ops; 285 286 if (neigh->nud_state & NUD_VALID) 287 neigh->output = neigh->ops->connected_output; 288 else 289 neigh->output = neigh->ops->output; 290 } 291 return 0; 292 } 293 294 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb) 295 { 296 dst_link_failure(skb); 297 kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_FAILED); 298 } 299 300 /* Create and send an arp packet. */ 301 static void arp_send_dst(int type, int ptype, __be32 dest_ip, 302 struct net_device *dev, __be32 src_ip, 303 const unsigned char *dest_hw, 304 const unsigned char *src_hw, 305 const unsigned char *target_hw, 306 struct dst_entry *dst) 307 { 308 struct sk_buff *skb; 309 310 /* arp on this interface. */ 311 if (dev->flags & IFF_NOARP) 312 return; 313 314 skb = arp_create(type, ptype, dest_ip, dev, src_ip, 315 dest_hw, src_hw, target_hw); 316 if (!skb) 317 return; 318 319 skb_dst_set(skb, dst_clone(dst)); 320 arp_xmit(skb); 321 } 322 323 void arp_send(int type, int ptype, __be32 dest_ip, 324 struct net_device *dev, __be32 src_ip, 325 const unsigned char *dest_hw, const unsigned char *src_hw, 326 const unsigned char *target_hw) 327 { 328 arp_send_dst(type, ptype, dest_ip, dev, src_ip, dest_hw, src_hw, 329 target_hw, NULL); 330 } 331 EXPORT_SYMBOL(arp_send); 332 333 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb) 334 { 335 __be32 saddr = 0; 336 u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL; 337 struct net_device *dev = neigh->dev; 338 __be32 target = *(__be32 *)neigh->primary_key; 339 int probes = atomic_read(&neigh->probes); 340 struct in_device *in_dev; 341 struct dst_entry *dst = NULL; 342 343 rcu_read_lock(); 344 in_dev = __in_dev_get_rcu(dev); 345 if (!in_dev) { 346 rcu_read_unlock(); 347 return; 348 } 349 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) { 350 default: 351 case 0: /* By default announce any local IP */ 352 if (skb && inet_addr_type_dev_table(dev_net(dev), dev, 353 ip_hdr(skb)->saddr) == RTN_LOCAL) 354 saddr = ip_hdr(skb)->saddr; 355 break; 356 case 1: /* Restrict announcements of saddr in same subnet */ 357 if (!skb) 358 break; 359 saddr = ip_hdr(skb)->saddr; 360 if (inet_addr_type_dev_table(dev_net(dev), dev, 361 saddr) == RTN_LOCAL) { 362 /* saddr should be known to target */ 363 if (inet_addr_onlink(in_dev, target, saddr)) 364 break; 365 } 366 saddr = 0; 367 break; 368 case 2: /* Avoid secondary IPs, get a primary/preferred one */ 369 break; 370 } 371 rcu_read_unlock(); 372 373 if (!saddr) 374 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK); 375 376 probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES); 377 if (probes < 0) { 378 if (!(READ_ONCE(neigh->nud_state) & NUD_VALID)) 379 pr_debug("trying to ucast probe in NUD_INVALID\n"); 380 neigh_ha_snapshot(dst_ha, neigh, dev); 381 dst_hw = dst_ha; 382 } else { 383 probes -= NEIGH_VAR(neigh->parms, APP_PROBES); 384 if (probes < 0) { 385 neigh_app_ns(neigh); 386 return; 387 } 388 } 389 390 if (skb && !(dev->priv_flags & IFF_XMIT_DST_RELEASE)) 391 dst = skb_dst(skb); 392 arp_send_dst(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr, 393 dst_hw, dev->dev_addr, NULL, dst); 394 } 395 396 static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip) 397 { 398 struct net *net = dev_net(in_dev->dev); 399 int scope; 400 401 switch (IN_DEV_ARP_IGNORE(in_dev)) { 402 case 0: /* Reply, the tip is already validated */ 403 return 0; 404 case 1: /* Reply only if tip is configured on the incoming interface */ 405 sip = 0; 406 scope = RT_SCOPE_HOST; 407 break; 408 case 2: /* 409 * Reply only if tip is configured on the incoming interface 410 * and is in same subnet as sip 411 */ 412 scope = RT_SCOPE_HOST; 413 break; 414 case 3: /* Do not reply for scope host addresses */ 415 sip = 0; 416 scope = RT_SCOPE_LINK; 417 in_dev = NULL; 418 break; 419 case 4: /* Reserved */ 420 case 5: 421 case 6: 422 case 7: 423 return 0; 424 case 8: /* Do not reply */ 425 return 1; 426 default: 427 return 0; 428 } 429 return !inet_confirm_addr(net, in_dev, sip, tip, scope); 430 } 431 432 static int arp_accept(struct in_device *in_dev, __be32 sip) 433 { 434 struct net *net = dev_net(in_dev->dev); 435 int scope = RT_SCOPE_LINK; 436 437 switch (IN_DEV_ARP_ACCEPT(in_dev)) { 438 case 0: /* Don't create new entries from garp */ 439 return 0; 440 case 1: /* Create new entries from garp */ 441 return 1; 442 case 2: /* Create a neighbor in the arp table only if sip 443 * is in the same subnet as an address configured 444 * on the interface that received the garp message 445 */ 446 return !!inet_confirm_addr(net, in_dev, sip, 0, scope); 447 default: 448 return 0; 449 } 450 } 451 452 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev) 453 { 454 struct rtable *rt; 455 int flag = 0; 456 /*unsigned long now; */ 457 struct net *net = dev_net(dev); 458 459 rt = ip_route_output(net, sip, tip, 0, l3mdev_master_ifindex_rcu(dev), 460 RT_SCOPE_UNIVERSE); 461 if (IS_ERR(rt)) 462 return 1; 463 if (rt->dst.dev != dev) { 464 __NET_INC_STATS(net, LINUX_MIB_ARPFILTER); 465 flag = 1; 466 } 467 ip_rt_put(rt); 468 return flag; 469 } 470 471 /* 472 * Check if we can use proxy ARP for this path 473 */ 474 static inline int arp_fwd_proxy(struct in_device *in_dev, 475 struct net_device *dev, struct rtable *rt) 476 { 477 struct in_device *out_dev; 478 int imi, omi = -1; 479 480 if (rt->dst.dev == dev) 481 return 0; 482 483 if (!IN_DEV_PROXY_ARP(in_dev)) 484 return 0; 485 imi = IN_DEV_MEDIUM_ID(in_dev); 486 if (imi == 0) 487 return 1; 488 if (imi == -1) 489 return 0; 490 491 /* place to check for proxy_arp for routes */ 492 493 out_dev = __in_dev_get_rcu(rt->dst.dev); 494 if (out_dev) 495 omi = IN_DEV_MEDIUM_ID(out_dev); 496 497 return omi != imi && omi != -1; 498 } 499 500 /* 501 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev) 502 * 503 * RFC3069 supports proxy arp replies back to the same interface. This 504 * is done to support (ethernet) switch features, like RFC 3069, where 505 * the individual ports are not allowed to communicate with each 506 * other, BUT they are allowed to talk to the upstream router. As 507 * described in RFC 3069, it is possible to allow these hosts to 508 * communicate through the upstream router, by proxy_arp'ing. 509 * 510 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation" 511 * 512 * This technology is known by different names: 513 * In RFC 3069 it is called VLAN Aggregation. 514 * Cisco and Allied Telesyn call it Private VLAN. 515 * Hewlett-Packard call it Source-Port filtering or port-isolation. 516 * Ericsson call it MAC-Forced Forwarding (RFC Draft). 517 * 518 */ 519 static inline int arp_fwd_pvlan(struct in_device *in_dev, 520 struct net_device *dev, struct rtable *rt, 521 __be32 sip, __be32 tip) 522 { 523 /* Private VLAN is only concerned about the same ethernet segment */ 524 if (rt->dst.dev != dev) 525 return 0; 526 527 /* Don't reply on self probes (often done by windowz boxes)*/ 528 if (sip == tip) 529 return 0; 530 531 if (IN_DEV_PROXY_ARP_PVLAN(in_dev)) 532 return 1; 533 else 534 return 0; 535 } 536 537 /* 538 * Interface to link layer: send routine and receive handler. 539 */ 540 541 /* 542 * Create an arp packet. If dest_hw is not set, we create a broadcast 543 * message. 544 */ 545 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip, 546 struct net_device *dev, __be32 src_ip, 547 const unsigned char *dest_hw, 548 const unsigned char *src_hw, 549 const unsigned char *target_hw) 550 { 551 struct sk_buff *skb; 552 struct arphdr *arp; 553 unsigned char *arp_ptr; 554 int hlen = LL_RESERVED_SPACE(dev); 555 int tlen = dev->needed_tailroom; 556 557 /* 558 * Allocate a buffer 559 */ 560 561 skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC); 562 if (!skb) 563 return NULL; 564 565 skb_reserve(skb, hlen); 566 skb_reset_network_header(skb); 567 arp = skb_put(skb, arp_hdr_len(dev)); 568 skb->dev = dev; 569 skb->protocol = htons(ETH_P_ARP); 570 if (!src_hw) 571 src_hw = dev->dev_addr; 572 if (!dest_hw) 573 dest_hw = dev->broadcast; 574 575 /* 576 * Fill the device header for the ARP frame 577 */ 578 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0) 579 goto out; 580 581 /* 582 * Fill out the arp protocol part. 583 * 584 * The arp hardware type should match the device type, except for FDDI, 585 * which (according to RFC 1390) should always equal 1 (Ethernet). 586 */ 587 /* 588 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the 589 * DIX code for the protocol. Make these device structure fields. 590 */ 591 switch (dev->type) { 592 default: 593 arp->ar_hrd = htons(dev->type); 594 arp->ar_pro = htons(ETH_P_IP); 595 break; 596 597 #if IS_ENABLED(CONFIG_AX25) 598 case ARPHRD_AX25: 599 arp->ar_hrd = htons(ARPHRD_AX25); 600 arp->ar_pro = htons(AX25_P_IP); 601 break; 602 603 #if IS_ENABLED(CONFIG_NETROM) 604 case ARPHRD_NETROM: 605 arp->ar_hrd = htons(ARPHRD_NETROM); 606 arp->ar_pro = htons(AX25_P_IP); 607 break; 608 #endif 609 #endif 610 611 #if IS_ENABLED(CONFIG_FDDI) 612 case ARPHRD_FDDI: 613 arp->ar_hrd = htons(ARPHRD_ETHER); 614 arp->ar_pro = htons(ETH_P_IP); 615 break; 616 #endif 617 } 618 619 arp->ar_hln = dev->addr_len; 620 arp->ar_pln = 4; 621 arp->ar_op = htons(type); 622 623 arp_ptr = (unsigned char *)(arp + 1); 624 625 memcpy(arp_ptr, src_hw, dev->addr_len); 626 arp_ptr += dev->addr_len; 627 memcpy(arp_ptr, &src_ip, 4); 628 arp_ptr += 4; 629 630 switch (dev->type) { 631 #if IS_ENABLED(CONFIG_FIREWIRE_NET) 632 case ARPHRD_IEEE1394: 633 break; 634 #endif 635 default: 636 if (target_hw) 637 memcpy(arp_ptr, target_hw, dev->addr_len); 638 else 639 memset(arp_ptr, 0, dev->addr_len); 640 arp_ptr += dev->addr_len; 641 } 642 memcpy(arp_ptr, &dest_ip, 4); 643 644 return skb; 645 646 out: 647 kfree_skb(skb); 648 return NULL; 649 } 650 EXPORT_SYMBOL(arp_create); 651 652 static int arp_xmit_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 653 { 654 return dev_queue_xmit(skb); 655 } 656 657 /* 658 * Send an arp packet. 659 */ 660 void arp_xmit(struct sk_buff *skb) 661 { 662 /* Send it off, maybe filter it using firewalling first. */ 663 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, 664 dev_net(skb->dev), NULL, skb, NULL, skb->dev, 665 arp_xmit_finish); 666 } 667 EXPORT_SYMBOL(arp_xmit); 668 669 static bool arp_is_garp(struct net *net, struct net_device *dev, 670 int *addr_type, __be16 ar_op, 671 __be32 sip, __be32 tip, 672 unsigned char *sha, unsigned char *tha) 673 { 674 bool is_garp = tip == sip; 675 676 /* Gratuitous ARP _replies_ also require target hwaddr to be 677 * the same as source. 678 */ 679 if (is_garp && ar_op == htons(ARPOP_REPLY)) 680 is_garp = 681 /* IPv4 over IEEE 1394 doesn't provide target 682 * hardware address field in its ARP payload. 683 */ 684 tha && 685 !memcmp(tha, sha, dev->addr_len); 686 687 if (is_garp) { 688 *addr_type = inet_addr_type_dev_table(net, dev, sip); 689 if (*addr_type != RTN_UNICAST) 690 is_garp = false; 691 } 692 return is_garp; 693 } 694 695 /* 696 * Process an arp request. 697 */ 698 699 static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb) 700 { 701 struct net_device *dev = skb->dev; 702 struct in_device *in_dev = __in_dev_get_rcu(dev); 703 struct arphdr *arp; 704 unsigned char *arp_ptr; 705 struct rtable *rt; 706 unsigned char *sha; 707 unsigned char *tha = NULL; 708 __be32 sip, tip; 709 u16 dev_type = dev->type; 710 int addr_type; 711 struct neighbour *n; 712 struct dst_entry *reply_dst = NULL; 713 bool is_garp = false; 714 715 /* arp_rcv below verifies the ARP header and verifies the device 716 * is ARP'able. 717 */ 718 719 if (!in_dev) 720 goto out_free_skb; 721 722 arp = arp_hdr(skb); 723 724 switch (dev_type) { 725 default: 726 if (arp->ar_pro != htons(ETH_P_IP) || 727 htons(dev_type) != arp->ar_hrd) 728 goto out_free_skb; 729 break; 730 case ARPHRD_ETHER: 731 case ARPHRD_FDDI: 732 case ARPHRD_IEEE802: 733 /* 734 * ETHERNET, and Fibre Channel (which are IEEE 802 735 * devices, according to RFC 2625) devices will accept ARP 736 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2). 737 * This is the case also of FDDI, where the RFC 1390 says that 738 * FDDI devices should accept ARP hardware of (1) Ethernet, 739 * however, to be more robust, we'll accept both 1 (Ethernet) 740 * or 6 (IEEE 802.2) 741 */ 742 if ((arp->ar_hrd != htons(ARPHRD_ETHER) && 743 arp->ar_hrd != htons(ARPHRD_IEEE802)) || 744 arp->ar_pro != htons(ETH_P_IP)) 745 goto out_free_skb; 746 break; 747 case ARPHRD_AX25: 748 if (arp->ar_pro != htons(AX25_P_IP) || 749 arp->ar_hrd != htons(ARPHRD_AX25)) 750 goto out_free_skb; 751 break; 752 case ARPHRD_NETROM: 753 if (arp->ar_pro != htons(AX25_P_IP) || 754 arp->ar_hrd != htons(ARPHRD_NETROM)) 755 goto out_free_skb; 756 break; 757 } 758 759 /* Understand only these message types */ 760 761 if (arp->ar_op != htons(ARPOP_REPLY) && 762 arp->ar_op != htons(ARPOP_REQUEST)) 763 goto out_free_skb; 764 765 /* 766 * Extract fields 767 */ 768 arp_ptr = (unsigned char *)(arp + 1); 769 sha = arp_ptr; 770 arp_ptr += dev->addr_len; 771 memcpy(&sip, arp_ptr, 4); 772 arp_ptr += 4; 773 switch (dev_type) { 774 #if IS_ENABLED(CONFIG_FIREWIRE_NET) 775 case ARPHRD_IEEE1394: 776 break; 777 #endif 778 default: 779 tha = arp_ptr; 780 arp_ptr += dev->addr_len; 781 } 782 memcpy(&tip, arp_ptr, 4); 783 /* 784 * Check for bad requests for 127.x.x.x and requests for multicast 785 * addresses. If this is one such, delete it. 786 */ 787 if (ipv4_is_multicast(tip) || 788 (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip))) 789 goto out_free_skb; 790 791 /* 792 * For some 802.11 wireless deployments (and possibly other networks), 793 * there will be an ARP proxy and gratuitous ARP frames are attacks 794 * and thus should not be accepted. 795 */ 796 if (sip == tip && IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP)) 797 goto out_free_skb; 798 799 /* 800 * Special case: We must set Frame Relay source Q.922 address 801 */ 802 if (dev_type == ARPHRD_DLCI) 803 sha = dev->broadcast; 804 805 /* 806 * Process entry. The idea here is we want to send a reply if it is a 807 * request for us or if it is a request for someone else that we hold 808 * a proxy for. We want to add an entry to our cache if it is a reply 809 * to us or if it is a request for our address. 810 * (The assumption for this last is that if someone is requesting our 811 * address, they are probably intending to talk to us, so it saves time 812 * if we cache their address. Their address is also probably not in 813 * our cache, since ours is not in their cache.) 814 * 815 * Putting this another way, we only care about replies if they are to 816 * us, in which case we add them to the cache. For requests, we care 817 * about those for us and those for our proxies. We reply to both, 818 * and in the case of requests for us we add the requester to the arp 819 * cache. 820 */ 821 822 if (arp->ar_op == htons(ARPOP_REQUEST) && skb_metadata_dst(skb)) 823 reply_dst = (struct dst_entry *) 824 iptunnel_metadata_reply(skb_metadata_dst(skb), 825 GFP_ATOMIC); 826 827 /* Special case: IPv4 duplicate address detection packet (RFC2131) */ 828 if (sip == 0) { 829 if (arp->ar_op == htons(ARPOP_REQUEST) && 830 inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL && 831 !arp_ignore(in_dev, sip, tip)) 832 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, 833 sha, dev->dev_addr, sha, reply_dst); 834 goto out_consume_skb; 835 } 836 837 if (arp->ar_op == htons(ARPOP_REQUEST) && 838 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) { 839 840 rt = skb_rtable(skb); 841 addr_type = rt->rt_type; 842 843 if (addr_type == RTN_LOCAL) { 844 int dont_send; 845 846 dont_send = arp_ignore(in_dev, sip, tip); 847 if (!dont_send && IN_DEV_ARPFILTER(in_dev)) 848 dont_send = arp_filter(sip, tip, dev); 849 if (!dont_send) { 850 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 851 if (n) { 852 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, 853 sip, dev, tip, sha, 854 dev->dev_addr, sha, 855 reply_dst); 856 neigh_release(n); 857 } 858 } 859 goto out_consume_skb; 860 } else if (IN_DEV_FORWARD(in_dev)) { 861 if (addr_type == RTN_UNICAST && 862 (arp_fwd_proxy(in_dev, dev, rt) || 863 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) || 864 (rt->dst.dev != dev && 865 pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) { 866 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 867 if (n) 868 neigh_release(n); 869 870 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED || 871 skb->pkt_type == PACKET_HOST || 872 NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) { 873 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, 874 sip, dev, tip, sha, 875 dev->dev_addr, sha, 876 reply_dst); 877 } else { 878 pneigh_enqueue(&arp_tbl, 879 in_dev->arp_parms, skb); 880 goto out_free_dst; 881 } 882 goto out_consume_skb; 883 } 884 } 885 } 886 887 /* Update our ARP tables */ 888 889 n = __neigh_lookup(&arp_tbl, &sip, dev, 0); 890 891 addr_type = -1; 892 if (n || arp_accept(in_dev, sip)) { 893 is_garp = arp_is_garp(net, dev, &addr_type, arp->ar_op, 894 sip, tip, sha, tha); 895 } 896 897 if (arp_accept(in_dev, sip)) { 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 if (!n && 903 (is_garp || 904 (arp->ar_op == htons(ARPOP_REPLY) && 905 (addr_type == RTN_UNICAST || 906 (addr_type < 0 && 907 /* postpone calculation to as late as possible */ 908 inet_addr_type_dev_table(net, dev, sip) == 909 RTN_UNICAST))))) 910 n = __neigh_lookup(&arp_tbl, &sip, dev, 1); 911 } 912 913 if (n) { 914 int state = NUD_REACHABLE; 915 int override; 916 917 /* If several different ARP replies follows back-to-back, 918 use the FIRST one. It is possible, if several proxy 919 agents are active. Taking the first reply prevents 920 arp trashing and chooses the fastest router. 921 */ 922 override = time_after(jiffies, 923 n->updated + 924 NEIGH_VAR(n->parms, LOCKTIME)) || 925 is_garp; 926 927 /* Broadcast replies and request packets 928 do not assert neighbour reachability. 929 */ 930 if (arp->ar_op != htons(ARPOP_REPLY) || 931 skb->pkt_type != PACKET_HOST) 932 state = NUD_STALE; 933 neigh_update(n, sha, state, 934 override ? NEIGH_UPDATE_F_OVERRIDE : 0, 0); 935 neigh_release(n); 936 } 937 938 out_consume_skb: 939 consume_skb(skb); 940 941 out_free_dst: 942 dst_release(reply_dst); 943 return NET_RX_SUCCESS; 944 945 out_free_skb: 946 kfree_skb(skb); 947 return NET_RX_DROP; 948 } 949 950 static void parp_redo(struct sk_buff *skb) 951 { 952 arp_process(dev_net(skb->dev), NULL, skb); 953 } 954 955 static int arp_is_multicast(const void *pkey) 956 { 957 return ipv4_is_multicast(*((__be32 *)pkey)); 958 } 959 960 /* 961 * Receive an arp request from the device layer. 962 */ 963 964 static int arp_rcv(struct sk_buff *skb, struct net_device *dev, 965 struct packet_type *pt, struct net_device *orig_dev) 966 { 967 const struct arphdr *arp; 968 969 /* do not tweak dropwatch on an ARP we will ignore */ 970 if (dev->flags & IFF_NOARP || 971 skb->pkt_type == PACKET_OTHERHOST || 972 skb->pkt_type == PACKET_LOOPBACK) 973 goto consumeskb; 974 975 skb = skb_share_check(skb, GFP_ATOMIC); 976 if (!skb) 977 goto out_of_mem; 978 979 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */ 980 if (!pskb_may_pull(skb, arp_hdr_len(dev))) 981 goto freeskb; 982 983 arp = arp_hdr(skb); 984 if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4) 985 goto freeskb; 986 987 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb)); 988 989 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, 990 dev_net(dev), NULL, skb, dev, NULL, 991 arp_process); 992 993 consumeskb: 994 consume_skb(skb); 995 return NET_RX_SUCCESS; 996 freeskb: 997 kfree_skb(skb); 998 out_of_mem: 999 return NET_RX_DROP; 1000 } 1001 1002 /* 1003 * User level interface (ioctl) 1004 */ 1005 1006 static struct net_device *arp_req_dev_by_name(struct net *net, struct arpreq *r, 1007 bool getarp) 1008 { 1009 struct net_device *dev; 1010 1011 if (getarp) 1012 dev = dev_get_by_name_rcu(net, r->arp_dev); 1013 else 1014 dev = __dev_get_by_name(net, r->arp_dev); 1015 if (!dev) 1016 return ERR_PTR(-ENODEV); 1017 1018 /* Mmmm... It is wrong... ARPHRD_NETROM == 0 */ 1019 if (!r->arp_ha.sa_family) 1020 r->arp_ha.sa_family = dev->type; 1021 1022 if ((r->arp_flags & ATF_COM) && r->arp_ha.sa_family != dev->type) 1023 return ERR_PTR(-EINVAL); 1024 1025 return dev; 1026 } 1027 1028 static struct net_device *arp_req_dev(struct net *net, struct arpreq *r) 1029 { 1030 struct net_device *dev; 1031 struct rtable *rt; 1032 __be32 ip; 1033 1034 if (r->arp_dev[0]) 1035 return arp_req_dev_by_name(net, r, false); 1036 1037 if (r->arp_flags & ATF_PUBL) 1038 return NULL; 1039 1040 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1041 1042 rt = ip_route_output(net, ip, 0, 0, 0, RT_SCOPE_LINK); 1043 if (IS_ERR(rt)) 1044 return ERR_CAST(rt); 1045 1046 dev = rt->dst.dev; 1047 ip_rt_put(rt); 1048 1049 if (!dev) 1050 return ERR_PTR(-EINVAL); 1051 1052 return dev; 1053 } 1054 1055 /* 1056 * Set (create) an ARP cache entry. 1057 */ 1058 1059 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on) 1060 { 1061 if (!dev) { 1062 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on; 1063 return 0; 1064 } 1065 if (__in_dev_get_rtnl(dev)) { 1066 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on); 1067 return 0; 1068 } 1069 return -ENXIO; 1070 } 1071 1072 static int arp_req_set_public(struct net *net, struct arpreq *r, 1073 struct net_device *dev) 1074 { 1075 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 1076 1077 if (!dev && (r->arp_flags & ATF_COM)) { 1078 dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family, 1079 r->arp_ha.sa_data); 1080 if (!dev) 1081 return -ENODEV; 1082 } 1083 if (mask) { 1084 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1085 1086 if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1)) 1087 return -ENOBUFS; 1088 return 0; 1089 } 1090 1091 return arp_req_set_proxy(net, dev, 1); 1092 } 1093 1094 static int arp_req_set(struct net *net, struct arpreq *r) 1095 { 1096 struct neighbour *neigh; 1097 struct net_device *dev; 1098 __be32 ip; 1099 int err; 1100 1101 dev = arp_req_dev(net, r); 1102 if (IS_ERR(dev)) 1103 return PTR_ERR(dev); 1104 1105 if (r->arp_flags & ATF_PUBL) 1106 return arp_req_set_public(net, r, dev); 1107 1108 switch (dev->type) { 1109 #if IS_ENABLED(CONFIG_FDDI) 1110 case ARPHRD_FDDI: 1111 /* 1112 * According to RFC 1390, FDDI devices should accept ARP 1113 * hardware types of 1 (Ethernet). However, to be more 1114 * robust, we'll accept hardware types of either 1 (Ethernet) 1115 * or 6 (IEEE 802.2). 1116 */ 1117 if (r->arp_ha.sa_family != ARPHRD_FDDI && 1118 r->arp_ha.sa_family != ARPHRD_ETHER && 1119 r->arp_ha.sa_family != ARPHRD_IEEE802) 1120 return -EINVAL; 1121 break; 1122 #endif 1123 default: 1124 if (r->arp_ha.sa_family != dev->type) 1125 return -EINVAL; 1126 break; 1127 } 1128 1129 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1130 1131 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev); 1132 err = PTR_ERR(neigh); 1133 if (!IS_ERR(neigh)) { 1134 unsigned int state = NUD_STALE; 1135 1136 if (r->arp_flags & ATF_PERM) { 1137 r->arp_flags |= ATF_COM; 1138 state = NUD_PERMANENT; 1139 } 1140 1141 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ? 1142 r->arp_ha.sa_data : NULL, state, 1143 NEIGH_UPDATE_F_OVERRIDE | 1144 NEIGH_UPDATE_F_ADMIN, 0); 1145 neigh_release(neigh); 1146 } 1147 return err; 1148 } 1149 1150 static unsigned int arp_state_to_flags(struct neighbour *neigh) 1151 { 1152 if (neigh->nud_state&NUD_PERMANENT) 1153 return ATF_PERM | ATF_COM; 1154 else if (neigh->nud_state&NUD_VALID) 1155 return ATF_COM; 1156 else 1157 return 0; 1158 } 1159 1160 /* 1161 * Get an ARP cache entry. 1162 */ 1163 1164 static int arp_req_get(struct net *net, struct arpreq *r) 1165 { 1166 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; 1167 struct neighbour *neigh; 1168 struct net_device *dev; 1169 1170 if (!r->arp_dev[0]) 1171 return -ENODEV; 1172 1173 dev = arp_req_dev_by_name(net, r, true); 1174 if (IS_ERR(dev)) 1175 return PTR_ERR(dev); 1176 1177 neigh = neigh_lookup(&arp_tbl, &ip, dev); 1178 if (!neigh) 1179 return -ENXIO; 1180 1181 if (READ_ONCE(neigh->nud_state) & NUD_NOARP) { 1182 neigh_release(neigh); 1183 return -ENXIO; 1184 } 1185 1186 read_lock_bh(&neigh->lock); 1187 memcpy(r->arp_ha.sa_data, neigh->ha, 1188 min(dev->addr_len, sizeof(r->arp_ha.sa_data_min))); 1189 r->arp_flags = arp_state_to_flags(neigh); 1190 read_unlock_bh(&neigh->lock); 1191 1192 neigh_release(neigh); 1193 1194 r->arp_ha.sa_family = dev->type; 1195 netdev_copy_name(dev, r->arp_dev); 1196 1197 return 0; 1198 } 1199 1200 int arp_invalidate(struct net_device *dev, __be32 ip, bool force) 1201 { 1202 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev); 1203 int err = -ENXIO; 1204 struct neigh_table *tbl = &arp_tbl; 1205 1206 if (neigh) { 1207 if ((READ_ONCE(neigh->nud_state) & NUD_VALID) && !force) { 1208 neigh_release(neigh); 1209 return 0; 1210 } 1211 1212 if (READ_ONCE(neigh->nud_state) & ~NUD_NOARP) 1213 err = neigh_update(neigh, NULL, NUD_FAILED, 1214 NEIGH_UPDATE_F_OVERRIDE| 1215 NEIGH_UPDATE_F_ADMIN, 0); 1216 write_lock_bh(&tbl->lock); 1217 neigh_release(neigh); 1218 neigh_remove_one(neigh, tbl); 1219 write_unlock_bh(&tbl->lock); 1220 } 1221 1222 return err; 1223 } 1224 1225 static int arp_req_delete_public(struct net *net, struct arpreq *r, 1226 struct net_device *dev) 1227 { 1228 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 1229 1230 if (mask) { 1231 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1232 1233 return pneigh_delete(&arp_tbl, net, &ip, dev); 1234 } 1235 1236 return arp_req_set_proxy(net, dev, 0); 1237 } 1238 1239 static int arp_req_delete(struct net *net, struct arpreq *r) 1240 { 1241 struct net_device *dev; 1242 __be32 ip; 1243 1244 dev = arp_req_dev(net, r); 1245 if (IS_ERR(dev)) 1246 return PTR_ERR(dev); 1247 1248 if (r->arp_flags & ATF_PUBL) 1249 return arp_req_delete_public(net, r, dev); 1250 1251 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1252 1253 return arp_invalidate(dev, ip, true); 1254 } 1255 1256 /* 1257 * Handle an ARP layer I/O control request. 1258 */ 1259 1260 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg) 1261 { 1262 struct arpreq r; 1263 __be32 *netmask; 1264 int err; 1265 1266 switch (cmd) { 1267 case SIOCDARP: 1268 case SIOCSARP: 1269 if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) 1270 return -EPERM; 1271 fallthrough; 1272 case SIOCGARP: 1273 err = copy_from_user(&r, arg, sizeof(struct arpreq)); 1274 if (err) 1275 return -EFAULT; 1276 break; 1277 default: 1278 return -EINVAL; 1279 } 1280 1281 if (r.arp_pa.sa_family != AF_INET) 1282 return -EPFNOSUPPORT; 1283 1284 if (!(r.arp_flags & ATF_PUBL) && 1285 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB))) 1286 return -EINVAL; 1287 1288 netmask = &((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr; 1289 if (!(r.arp_flags & ATF_NETMASK)) 1290 *netmask = htonl(0xFFFFFFFFUL); 1291 else if (*netmask && *netmask != htonl(0xFFFFFFFFUL)) 1292 return -EINVAL; 1293 1294 switch (cmd) { 1295 case SIOCDARP: 1296 rtnl_lock(); 1297 err = arp_req_delete(net, &r); 1298 rtnl_unlock(); 1299 break; 1300 case SIOCSARP: 1301 rtnl_lock(); 1302 err = arp_req_set(net, &r); 1303 rtnl_unlock(); 1304 break; 1305 case SIOCGARP: 1306 rcu_read_lock(); 1307 err = arp_req_get(net, &r); 1308 rcu_read_unlock(); 1309 1310 if (!err && copy_to_user(arg, &r, sizeof(r))) 1311 err = -EFAULT; 1312 break; 1313 } 1314 1315 return err; 1316 } 1317 1318 static int arp_netdev_event(struct notifier_block *this, unsigned long event, 1319 void *ptr) 1320 { 1321 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 1322 struct netdev_notifier_change_info *change_info; 1323 struct in_device *in_dev; 1324 bool evict_nocarrier; 1325 1326 switch (event) { 1327 case NETDEV_CHANGEADDR: 1328 neigh_changeaddr(&arp_tbl, dev); 1329 rt_cache_flush(dev_net(dev)); 1330 break; 1331 case NETDEV_CHANGE: 1332 change_info = ptr; 1333 if (change_info->flags_changed & IFF_NOARP) 1334 neigh_changeaddr(&arp_tbl, dev); 1335 1336 in_dev = __in_dev_get_rtnl(dev); 1337 if (!in_dev) 1338 evict_nocarrier = true; 1339 else 1340 evict_nocarrier = IN_DEV_ARP_EVICT_NOCARRIER(in_dev); 1341 1342 if (evict_nocarrier && !netif_carrier_ok(dev)) 1343 neigh_carrier_down(&arp_tbl, dev); 1344 break; 1345 default: 1346 break; 1347 } 1348 1349 return NOTIFY_DONE; 1350 } 1351 1352 static struct notifier_block arp_netdev_notifier = { 1353 .notifier_call = arp_netdev_event, 1354 }; 1355 1356 /* Note, that it is not on notifier chain. 1357 It is necessary, that this routine was called after route cache will be 1358 flushed. 1359 */ 1360 void arp_ifdown(struct net_device *dev) 1361 { 1362 neigh_ifdown(&arp_tbl, dev); 1363 } 1364 1365 1366 /* 1367 * Called once on startup. 1368 */ 1369 1370 static struct packet_type arp_packet_type __read_mostly = { 1371 .type = cpu_to_be16(ETH_P_ARP), 1372 .func = arp_rcv, 1373 }; 1374 1375 #ifdef CONFIG_PROC_FS 1376 #if IS_ENABLED(CONFIG_AX25) 1377 1378 /* 1379 * ax25 -> ASCII conversion 1380 */ 1381 static void ax2asc2(ax25_address *a, char *buf) 1382 { 1383 char c, *s; 1384 int n; 1385 1386 for (n = 0, s = buf; n < 6; n++) { 1387 c = (a->ax25_call[n] >> 1) & 0x7F; 1388 1389 if (c != ' ') 1390 *s++ = c; 1391 } 1392 1393 *s++ = '-'; 1394 n = (a->ax25_call[6] >> 1) & 0x0F; 1395 if (n > 9) { 1396 *s++ = '1'; 1397 n -= 10; 1398 } 1399 1400 *s++ = n + '0'; 1401 *s++ = '\0'; 1402 1403 if (*buf == '\0' || *buf == '-') { 1404 buf[0] = '*'; 1405 buf[1] = '\0'; 1406 } 1407 } 1408 #endif /* CONFIG_AX25 */ 1409 1410 #define HBUFFERLEN 30 1411 1412 static void arp_format_neigh_entry(struct seq_file *seq, 1413 struct neighbour *n) 1414 { 1415 char hbuffer[HBUFFERLEN]; 1416 int k, j; 1417 char tbuf[16]; 1418 struct net_device *dev = n->dev; 1419 int hatype = dev->type; 1420 1421 read_lock(&n->lock); 1422 /* Convert hardware address to XX:XX:XX:XX ... form. */ 1423 #if IS_ENABLED(CONFIG_AX25) 1424 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM) 1425 ax2asc2((ax25_address *)n->ha, hbuffer); 1426 else { 1427 #endif 1428 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) { 1429 hbuffer[k++] = hex_asc_hi(n->ha[j]); 1430 hbuffer[k++] = hex_asc_lo(n->ha[j]); 1431 hbuffer[k++] = ':'; 1432 } 1433 if (k != 0) 1434 --k; 1435 hbuffer[k] = 0; 1436 #if IS_ENABLED(CONFIG_AX25) 1437 } 1438 #endif 1439 sprintf(tbuf, "%pI4", n->primary_key); 1440 seq_printf(seq, "%-16s 0x%-10x0x%-10x%-17s * %s\n", 1441 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name); 1442 read_unlock(&n->lock); 1443 } 1444 1445 static void arp_format_pneigh_entry(struct seq_file *seq, 1446 struct pneigh_entry *n) 1447 { 1448 struct net_device *dev = n->dev; 1449 int hatype = dev ? dev->type : 0; 1450 char tbuf[16]; 1451 1452 sprintf(tbuf, "%pI4", n->key); 1453 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n", 1454 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00", 1455 dev ? dev->name : "*"); 1456 } 1457 1458 static int arp_seq_show(struct seq_file *seq, void *v) 1459 { 1460 if (v == SEQ_START_TOKEN) { 1461 seq_puts(seq, "IP address HW type Flags " 1462 "HW address Mask Device\n"); 1463 } else { 1464 struct neigh_seq_state *state = seq->private; 1465 1466 if (state->flags & NEIGH_SEQ_IS_PNEIGH) 1467 arp_format_pneigh_entry(seq, v); 1468 else 1469 arp_format_neigh_entry(seq, v); 1470 } 1471 1472 return 0; 1473 } 1474 1475 static void *arp_seq_start(struct seq_file *seq, loff_t *pos) 1476 { 1477 /* Don't want to confuse "arp -a" w/ magic entries, 1478 * so we tell the generic iterator to skip NUD_NOARP. 1479 */ 1480 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP); 1481 } 1482 1483 static const struct seq_operations arp_seq_ops = { 1484 .start = arp_seq_start, 1485 .next = neigh_seq_next, 1486 .stop = neigh_seq_stop, 1487 .show = arp_seq_show, 1488 }; 1489 #endif /* CONFIG_PROC_FS */ 1490 1491 static int __net_init arp_net_init(struct net *net) 1492 { 1493 if (!proc_create_net("arp", 0444, net->proc_net, &arp_seq_ops, 1494 sizeof(struct neigh_seq_state))) 1495 return -ENOMEM; 1496 return 0; 1497 } 1498 1499 static void __net_exit arp_net_exit(struct net *net) 1500 { 1501 remove_proc_entry("arp", net->proc_net); 1502 } 1503 1504 static struct pernet_operations arp_net_ops = { 1505 .init = arp_net_init, 1506 .exit = arp_net_exit, 1507 }; 1508 1509 void __init arp_init(void) 1510 { 1511 neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl); 1512 1513 dev_add_pack(&arp_packet_type); 1514 register_pernet_subsys(&arp_net_ops); 1515 #ifdef CONFIG_SYSCTL 1516 neigh_sysctl_register(NULL, &arp_tbl.parms, NULL); 1517 #endif 1518 register_netdevice_notifier(&arp_netdev_notifier); 1519 } 1520