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/hex.h> 83 #include <linux/in.h> 84 #include <linux/mm.h> 85 #include <linux/inet.h> 86 #include <linux/inetdevice.h> 87 #include <linux/netdevice.h> 88 #include <linux/etherdevice.h> 89 #include <linux/fddidevice.h> 90 #include <linux/if_arp.h> 91 #include <linux/skbuff.h> 92 #include <linux/proc_fs.h> 93 #include <linux/seq_file.h> 94 #include <linux/stat.h> 95 #include <linux/init.h> 96 #include <linux/net.h> 97 #include <linux/rcupdate.h> 98 #include <linux/slab.h> 99 #ifdef CONFIG_SYSCTL 100 #include <linux/sysctl.h> 101 #endif 102 103 #include <net/net_namespace.h> 104 #include <net/ip.h> 105 #include <net/icmp.h> 106 #include <net/route.h> 107 #include <net/protocol.h> 108 #include <net/tcp.h> 109 #include <net/sock.h> 110 #include <net/arp.h> 111 #include <net/ax25.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 static 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_DEFAULT, 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 }; 185 186 int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir) 187 { 188 switch (dev->type) { 189 case ARPHRD_ETHER: 190 case ARPHRD_FDDI: 191 case ARPHRD_IEEE802: 192 ip_eth_mc_map(addr, haddr); 193 return 0; 194 case ARPHRD_INFINIBAND: 195 ip_ib_mc_map(addr, dev->broadcast, haddr); 196 return 0; 197 case ARPHRD_IPGRE: 198 ip_ipgre_mc_map(addr, dev->broadcast, haddr); 199 return 0; 200 default: 201 if (dir) { 202 memcpy(haddr, dev->broadcast, dev->addr_len); 203 return 0; 204 } 205 } 206 return -EINVAL; 207 } 208 209 210 static u32 arp_hash(const void *pkey, 211 const struct net_device *dev, 212 __u32 *hash_rnd) 213 { 214 return arp_hashfn(pkey, dev, hash_rnd); 215 } 216 217 static bool arp_key_eq(const struct neighbour *neigh, const void *pkey) 218 { 219 return neigh_key_eq32(neigh, pkey); 220 } 221 222 static int arp_constructor(struct neighbour *neigh) 223 { 224 struct net_device *dev = neigh->dev; 225 struct net *net = dev_net(dev); 226 u32 inaddr_any = INADDR_ANY; 227 struct neigh_parms *parms; 228 struct in_device *in_dev; 229 struct neigh_table *tbl; 230 __be32 addr; 231 232 tbl = arp_table(net); 233 234 if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT)) 235 memcpy(neigh->primary_key, &inaddr_any, tbl->key_len); 236 237 addr = *(__be32 *)neigh->primary_key; 238 rcu_read_lock(); 239 in_dev = __in_dev_get_rcu(dev); 240 if (!in_dev) { 241 rcu_read_unlock(); 242 return -EINVAL; 243 } 244 245 neigh->type = inet_addr_type_dev_table(net, dev, addr); 246 247 parms = in_dev->arp_parms; 248 __neigh_parms_put(neigh->parms); 249 neigh->parms = neigh_parms_clone(parms); 250 rcu_read_unlock(); 251 252 if (!dev->header_ops) { 253 neigh->nud_state = NUD_NOARP; 254 neigh->ops = &arp_direct_ops; 255 neigh->output = neigh_direct_output; 256 } else { 257 /* Good devices (checked by reading texts, but only Ethernet is 258 tested) 259 260 ARPHRD_ETHER: (ethernet, apfddi) 261 ARPHRD_FDDI: (fddi) 262 ARPHRD_IEEE802: (tr) 263 ARPHRD_METRICOM: (strip) 264 ARPHRD_ARCNET: 265 etc. etc. etc. 266 267 ARPHRD_IPDDP will also work, if author repairs it. 268 I did not it, because this driver does not work even 269 in old paradigm. 270 */ 271 272 if (neigh->type == RTN_MULTICAST) { 273 neigh->nud_state = NUD_NOARP; 274 arp_mc_map(addr, neigh->ha, dev, 1); 275 } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) { 276 neigh->nud_state = NUD_NOARP; 277 memcpy(neigh->ha, dev->dev_addr, dev->addr_len); 278 } else if (neigh->type == RTN_BROADCAST || 279 (dev->flags & IFF_POINTOPOINT)) { 280 neigh->nud_state = NUD_NOARP; 281 memcpy(neigh->ha, dev->broadcast, dev->addr_len); 282 } 283 284 if (dev->header_ops->cache) 285 neigh->ops = &arp_hh_ops; 286 else 287 neigh->ops = &arp_generic_ops; 288 289 if (neigh->nud_state & NUD_VALID) 290 neigh->output = neigh->ops->connected_output; 291 else 292 neigh->output = neigh->ops->output; 293 } 294 return 0; 295 } 296 297 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb) 298 { 299 dst_link_failure(skb); 300 kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_FAILED); 301 } 302 303 /* Create and send an arp packet. */ 304 static void arp_send_dst(int type, int ptype, __be32 dest_ip, 305 struct net_device *dev, __be32 src_ip, 306 const unsigned char *dest_hw, 307 const unsigned char *src_hw, 308 const unsigned char *target_hw, 309 struct dst_entry *dst) 310 { 311 struct sk_buff *skb; 312 313 /* arp on this interface. */ 314 if (dev->flags & IFF_NOARP) 315 return; 316 317 skb = arp_create(type, ptype, dest_ip, dev, src_ip, 318 dest_hw, src_hw, target_hw); 319 if (!skb) 320 return; 321 322 skb_dst_set(skb, dst_clone(dst)); 323 arp_xmit(skb); 324 } 325 326 void arp_send(int type, int ptype, __be32 dest_ip, 327 struct net_device *dev, __be32 src_ip, 328 const unsigned char *dest_hw, const unsigned char *src_hw, 329 const unsigned char *target_hw) 330 { 331 arp_send_dst(type, ptype, dest_ip, dev, src_ip, dest_hw, src_hw, 332 target_hw, NULL); 333 } 334 EXPORT_SYMBOL(arp_send); 335 336 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb) 337 { 338 __be32 saddr = 0; 339 u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL; 340 struct net_device *dev = neigh->dev; 341 __be32 target = *(__be32 *)neigh->primary_key; 342 int probes = atomic_read(&neigh->probes); 343 struct in_device *in_dev; 344 struct dst_entry *dst = NULL; 345 346 rcu_read_lock(); 347 in_dev = __in_dev_get_rcu(dev); 348 if (!in_dev) { 349 rcu_read_unlock(); 350 return; 351 } 352 switch (IN_DEV_ARP_ANNOUNCE(in_dev)) { 353 default: 354 case 0: /* By default announce any local IP */ 355 if (skb && inet_addr_type_dev_table(dev_net(dev), dev, 356 ip_hdr(skb)->saddr) == RTN_LOCAL) 357 saddr = ip_hdr(skb)->saddr; 358 break; 359 case 1: /* Restrict announcements of saddr in same subnet */ 360 if (!skb) 361 break; 362 saddr = ip_hdr(skb)->saddr; 363 if (inet_addr_type_dev_table(dev_net(dev), dev, 364 saddr) == RTN_LOCAL) { 365 /* saddr should be known to target */ 366 if (inet_addr_onlink(in_dev, target, saddr)) 367 break; 368 } 369 saddr = 0; 370 break; 371 case 2: /* Avoid secondary IPs, get a primary/preferred one */ 372 break; 373 } 374 rcu_read_unlock(); 375 376 if (!saddr) 377 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK); 378 379 probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES); 380 if (probes < 0) { 381 if (!(READ_ONCE(neigh->nud_state) & NUD_VALID)) 382 pr_debug("trying to ucast probe in NUD_INVALID\n"); 383 neigh_ha_snapshot(dst_ha, neigh, dev); 384 dst_hw = dst_ha; 385 } else { 386 probes -= NEIGH_VAR(neigh->parms, APP_PROBES); 387 if (probes < 0) { 388 neigh_app_ns(neigh); 389 return; 390 } 391 } 392 393 if (skb && !(dev->priv_flags & IFF_XMIT_DST_RELEASE)) 394 dst = skb_dst(skb); 395 arp_send_dst(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr, 396 dst_hw, dev->dev_addr, NULL, dst); 397 } 398 399 static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip) 400 { 401 struct net *net = dev_net(in_dev->dev); 402 int scope; 403 404 switch (IN_DEV_ARP_IGNORE(in_dev)) { 405 case 0: /* Reply, the tip is already validated */ 406 return 0; 407 case 1: /* Reply only if tip is configured on the incoming interface */ 408 sip = 0; 409 scope = RT_SCOPE_HOST; 410 break; 411 case 2: /* 412 * Reply only if tip is configured on the incoming interface 413 * and is in same subnet as sip 414 */ 415 scope = RT_SCOPE_HOST; 416 break; 417 case 3: /* Do not reply for scope host addresses */ 418 sip = 0; 419 scope = RT_SCOPE_LINK; 420 in_dev = NULL; 421 break; 422 case 4: /* Reserved */ 423 case 5: 424 case 6: 425 case 7: 426 return 0; 427 case 8: /* Do not reply */ 428 return 1; 429 default: 430 return 0; 431 } 432 return !inet_confirm_addr(net, in_dev, sip, tip, scope); 433 } 434 435 static int arp_accept(struct in_device *in_dev, __be32 sip) 436 { 437 struct net *net = dev_net(in_dev->dev); 438 int scope = RT_SCOPE_LINK; 439 440 switch (IN_DEV_ARP_ACCEPT(in_dev)) { 441 case 0: /* Don't create new entries from garp */ 442 return 0; 443 case 1: /* Create new entries from garp */ 444 return 1; 445 case 2: /* Create a neighbor in the arp table only if sip 446 * is in the same subnet as an address configured 447 * on the interface that received the garp message 448 */ 449 return !!inet_confirm_addr(net, in_dev, sip, 0, scope); 450 default: 451 return 0; 452 } 453 } 454 455 static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev) 456 { 457 struct rtable *rt; 458 int flag = 0; 459 /*unsigned long now; */ 460 struct net *net = dev_net(dev); 461 462 rt = ip_route_output(net, sip, tip, 0, l3mdev_master_ifindex_rcu(dev), 463 RT_SCOPE_UNIVERSE); 464 if (IS_ERR(rt)) 465 return 1; 466 if (rt->dst.dev != dev) { 467 __NET_INC_STATS(net, LINUX_MIB_ARPFILTER); 468 flag = 1; 469 } 470 ip_rt_put(rt); 471 return flag; 472 } 473 474 /* 475 * Check if we can use proxy ARP for this path 476 */ 477 static inline int arp_fwd_proxy(struct in_device *in_dev, 478 struct net_device *dev, struct rtable *rt) 479 { 480 struct in_device *out_dev; 481 int imi, omi = -1; 482 483 if (rt->dst.dev == dev) 484 return 0; 485 486 if (!IN_DEV_PROXY_ARP(in_dev)) 487 return 0; 488 imi = IN_DEV_MEDIUM_ID(in_dev); 489 if (imi == 0) 490 return 1; 491 if (imi == -1) 492 return 0; 493 494 /* place to check for proxy_arp for routes */ 495 496 out_dev = __in_dev_get_rcu(rt->dst.dev); 497 if (out_dev) 498 omi = IN_DEV_MEDIUM_ID(out_dev); 499 500 return omi != imi && omi != -1; 501 } 502 503 /* 504 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev) 505 * 506 * RFC3069 supports proxy arp replies back to the same interface. This 507 * is done to support (ethernet) switch features, like RFC 3069, where 508 * the individual ports are not allowed to communicate with each 509 * other, BUT they are allowed to talk to the upstream router. As 510 * described in RFC 3069, it is possible to allow these hosts to 511 * communicate through the upstream router, by proxy_arp'ing. 512 * 513 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation" 514 * 515 * This technology is known by different names: 516 * In RFC 3069 it is called VLAN Aggregation. 517 * Cisco and Allied Telesyn call it Private VLAN. 518 * Hewlett-Packard call it Source-Port filtering or port-isolation. 519 * Ericsson call it MAC-Forced Forwarding (RFC Draft). 520 * 521 */ 522 static inline int arp_fwd_pvlan(struct in_device *in_dev, 523 struct net_device *dev, struct rtable *rt, 524 __be32 sip, __be32 tip) 525 { 526 /* Private VLAN is only concerned about the same ethernet segment */ 527 if (rt->dst.dev != dev) 528 return 0; 529 530 /* Don't reply on self probes (often done by windowz boxes)*/ 531 if (sip == tip) 532 return 0; 533 534 if (IN_DEV_PROXY_ARP_PVLAN(in_dev)) 535 return 1; 536 else 537 return 0; 538 } 539 540 /* 541 * Interface to link layer: send routine and receive handler. 542 */ 543 544 /* 545 * Create an arp packet. If dest_hw is not set, we create a broadcast 546 * message. 547 */ 548 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip, 549 struct net_device *dev, __be32 src_ip, 550 const unsigned char *dest_hw, 551 const unsigned char *src_hw, 552 const unsigned char *target_hw) 553 { 554 struct sk_buff *skb; 555 struct arphdr *arp; 556 unsigned char *arp_ptr; 557 int hlen = LL_RESERVED_SPACE(dev); 558 int tlen = dev->needed_tailroom; 559 560 /* 561 * Allocate a buffer 562 */ 563 564 skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC); 565 if (!skb) 566 return NULL; 567 568 skb_reserve(skb, hlen); 569 skb_reset_network_header(skb); 570 skb_put(skb, arp_hdr_len(dev)); 571 skb->dev = dev; 572 skb->protocol = htons(ETH_P_ARP); 573 if (!src_hw) 574 src_hw = dev->dev_addr; 575 if (!dest_hw) 576 dest_hw = dev->broadcast; 577 578 /* Fill the device header for the ARP frame. 579 * Note: skb->head can be changed. 580 */ 581 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0) 582 goto out; 583 584 arp = arp_hdr(skb); 585 /* 586 * Fill out the arp protocol part. 587 * 588 * The arp hardware type should match the device type, except for FDDI, 589 * which (according to RFC 1390) should always equal 1 (Ethernet). 590 */ 591 /* 592 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the 593 * DIX code for the protocol. Make these device structure fields. 594 */ 595 switch (dev->type) { 596 default: 597 arp->ar_hrd = htons(dev->type); 598 arp->ar_pro = htons(ETH_P_IP); 599 break; 600 601 #if IS_ENABLED(CONFIG_AX25) 602 case ARPHRD_AX25: 603 arp->ar_hrd = htons(ARPHRD_AX25); 604 arp->ar_pro = htons(AX25_P_IP); 605 break; 606 607 #if IS_ENABLED(CONFIG_NETROM) 608 case ARPHRD_NETROM: 609 arp->ar_hrd = htons(ARPHRD_NETROM); 610 arp->ar_pro = htons(AX25_P_IP); 611 break; 612 #endif 613 #endif 614 615 #if IS_ENABLED(CONFIG_FDDI) 616 case ARPHRD_FDDI: 617 arp->ar_hrd = htons(ARPHRD_ETHER); 618 arp->ar_pro = htons(ETH_P_IP); 619 break; 620 #endif 621 } 622 623 arp->ar_hln = dev->addr_len; 624 arp->ar_pln = 4; 625 arp->ar_op = htons(type); 626 627 arp_ptr = (unsigned char *)(arp + 1); 628 629 memcpy(arp_ptr, src_hw, dev->addr_len); 630 arp_ptr += dev->addr_len; 631 memcpy(arp_ptr, &src_ip, 4); 632 arp_ptr += 4; 633 634 switch (dev->type) { 635 #if IS_ENABLED(CONFIG_FIREWIRE_NET) 636 case ARPHRD_IEEE1394: 637 break; 638 #endif 639 default: 640 if (target_hw) 641 memcpy(arp_ptr, target_hw, dev->addr_len); 642 else 643 memset(arp_ptr, 0, dev->addr_len); 644 arp_ptr += dev->addr_len; 645 } 646 memcpy(arp_ptr, &dest_ip, 4); 647 648 return skb; 649 650 out: 651 kfree_skb(skb); 652 return NULL; 653 } 654 EXPORT_SYMBOL(arp_create); 655 656 static int arp_xmit_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 657 { 658 return dev_queue_xmit(skb); 659 } 660 661 /* 662 * Send an arp packet. 663 */ 664 void arp_xmit(struct sk_buff *skb) 665 { 666 rcu_read_lock(); 667 /* Send it off, maybe filter it using firewalling first. */ 668 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, 669 dev_net_rcu(skb->dev), NULL, skb, NULL, skb->dev, 670 arp_xmit_finish); 671 rcu_read_unlock(); 672 } 673 EXPORT_SYMBOL(arp_xmit); 674 675 static bool arp_is_garp(struct net *net, struct net_device *dev, 676 int *addr_type, __be16 ar_op, 677 __be32 sip, __be32 tip, 678 unsigned char *sha, unsigned char *tha) 679 { 680 bool is_garp = tip == sip; 681 682 /* Gratuitous ARP _replies_ also require target hwaddr to be 683 * the same as source. 684 */ 685 if (is_garp && ar_op == htons(ARPOP_REPLY)) 686 is_garp = 687 /* IPv4 over IEEE 1394 doesn't provide target 688 * hardware address field in its ARP payload. 689 */ 690 tha && 691 !memcmp(tha, sha, dev->addr_len); 692 693 if (is_garp) { 694 *addr_type = inet_addr_type_dev_table(net, dev, sip); 695 if (*addr_type != RTN_UNICAST) 696 is_garp = false; 697 } 698 return is_garp; 699 } 700 701 /* 702 * Process an arp request. 703 */ 704 705 static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb) 706 { 707 struct neigh_table *tbl = arp_table(net); 708 struct dst_entry *reply_dst = NULL; 709 struct net_device *dev = skb->dev; 710 unsigned char *sha, *tha = NULL; 711 struct in_device *in_dev; 712 u16 dev_type = dev->type; 713 unsigned char *arp_ptr; 714 bool is_garp = false; 715 struct neighbour *n; 716 struct arphdr *arp; 717 struct rtable *rt; 718 __be32 sip, tip; 719 int addr_type; 720 721 /* arp_rcv below verifies the ARP header and verifies the device 722 * is ARP'able. 723 */ 724 in_dev = __in_dev_get_rcu(dev); 725 if (!in_dev) 726 goto out_free_skb; 727 728 arp = arp_hdr(skb); 729 730 switch (dev_type) { 731 default: 732 if (arp->ar_pro != htons(ETH_P_IP) || 733 htons(dev_type) != arp->ar_hrd) 734 goto out_free_skb; 735 break; 736 case ARPHRD_ETHER: 737 case ARPHRD_FDDI: 738 case ARPHRD_IEEE802: 739 /* 740 * ETHERNET, and Fibre Channel (which are IEEE 802 741 * devices, according to RFC 2625) devices will accept ARP 742 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2). 743 * This is the case also of FDDI, where the RFC 1390 says that 744 * FDDI devices should accept ARP hardware of (1) Ethernet, 745 * however, to be more robust, we'll accept both 1 (Ethernet) 746 * or 6 (IEEE 802.2) 747 */ 748 if ((arp->ar_hrd != htons(ARPHRD_ETHER) && 749 arp->ar_hrd != htons(ARPHRD_IEEE802)) || 750 arp->ar_pro != htons(ETH_P_IP)) 751 goto out_free_skb; 752 break; 753 case ARPHRD_AX25: 754 if (arp->ar_pro != htons(AX25_P_IP) || 755 arp->ar_hrd != htons(ARPHRD_AX25)) 756 goto out_free_skb; 757 break; 758 case ARPHRD_NETROM: 759 if (arp->ar_pro != htons(AX25_P_IP) || 760 arp->ar_hrd != htons(ARPHRD_NETROM)) 761 goto out_free_skb; 762 break; 763 } 764 765 /* Understand only these message types */ 766 767 if (arp->ar_op != htons(ARPOP_REPLY) && 768 arp->ar_op != htons(ARPOP_REQUEST)) 769 goto out_free_skb; 770 771 /* 772 * Extract fields 773 */ 774 arp_ptr = (unsigned char *)(arp + 1); 775 sha = arp_ptr; 776 arp_ptr += dev->addr_len; 777 memcpy(&sip, arp_ptr, 4); 778 arp_ptr += 4; 779 switch (dev_type) { 780 #if IS_ENABLED(CONFIG_FIREWIRE_NET) 781 case ARPHRD_IEEE1394: 782 break; 783 #endif 784 default: 785 tha = arp_ptr; 786 arp_ptr += dev->addr_len; 787 } 788 memcpy(&tip, arp_ptr, 4); 789 /* 790 * Check for bad requests for 127.x.x.x and requests for multicast 791 * addresses. If this is one such, delete it. 792 */ 793 if (ipv4_is_multicast(tip) || 794 (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip))) 795 goto out_free_skb; 796 797 /* 798 * For some 802.11 wireless deployments (and possibly other networks), 799 * there will be an ARP proxy and gratuitous ARP frames are attacks 800 * and thus should not be accepted. 801 */ 802 if (sip == tip && IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP)) 803 goto out_free_skb; 804 805 /* 806 * Special case: We must set Frame Relay source Q.922 address 807 */ 808 if (dev_type == ARPHRD_DLCI) 809 sha = dev->broadcast; 810 811 /* 812 * Process entry. The idea here is we want to send a reply if it is a 813 * request for us or if it is a request for someone else that we hold 814 * a proxy for. We want to add an entry to our cache if it is a reply 815 * to us or if it is a request for our address. 816 * (The assumption for this last is that if someone is requesting our 817 * address, they are probably intending to talk to us, so it saves time 818 * if we cache their address. Their address is also probably not in 819 * our cache, since ours is not in their cache.) 820 * 821 * Putting this another way, we only care about replies if they are to 822 * us, in which case we add them to the cache. For requests, we care 823 * about those for us and those for our proxies. We reply to both, 824 * and in the case of requests for us we add the requester to the arp 825 * cache. 826 */ 827 828 if (arp->ar_op == htons(ARPOP_REQUEST) && skb_metadata_dst(skb)) 829 reply_dst = (struct dst_entry *) 830 iptunnel_metadata_reply(skb_metadata_dst(skb), 831 GFP_ATOMIC); 832 833 /* Special case: IPv4 duplicate address detection packet (RFC2131) */ 834 if (sip == 0) { 835 if (arp->ar_op == htons(ARPOP_REQUEST) && 836 inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL && 837 !arp_ignore(in_dev, sip, tip)) 838 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, 839 sha, dev->dev_addr, sha, reply_dst); 840 goto out_consume_skb; 841 } 842 843 if (arp->ar_op == htons(ARPOP_REQUEST) && 844 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) { 845 846 rt = skb_rtable(skb); 847 addr_type = rt->rt_type; 848 849 if (addr_type == RTN_LOCAL) { 850 int dont_send; 851 852 dont_send = arp_ignore(in_dev, sip, tip); 853 if (!dont_send && IN_DEV_ARPFILTER(in_dev)) 854 dont_send = arp_filter(sip, tip, dev); 855 if (!dont_send) { 856 n = neigh_event_ns(tbl, sha, &sip, dev); 857 if (n) { 858 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, 859 sip, dev, tip, sha, 860 dev->dev_addr, sha, 861 reply_dst); 862 neigh_release(n); 863 } 864 } 865 goto out_consume_skb; 866 } else if (IN_DEV_FORWARD(in_dev)) { 867 if (addr_type == RTN_UNICAST && 868 (arp_fwd_proxy(in_dev, dev, rt) || 869 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) || 870 (rt->dst.dev != dev && 871 pneigh_lookup(tbl, &tip, dev)))) { 872 n = neigh_event_ns(tbl, sha, &sip, dev); 873 if (n) 874 neigh_release(n); 875 876 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED || 877 skb->pkt_type == PACKET_HOST || 878 NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) { 879 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, 880 sip, dev, tip, sha, 881 dev->dev_addr, sha, 882 reply_dst); 883 } else { 884 pneigh_enqueue(tbl, 885 in_dev->arp_parms, skb); 886 goto out_free_dst; 887 } 888 goto out_consume_skb; 889 } 890 } 891 } 892 893 /* Update our ARP tables */ 894 895 n = ipv4_neigh_lookup(dev, &sip); 896 897 addr_type = -1; 898 if (n || arp_accept(in_dev, sip)) { 899 is_garp = arp_is_garp(net, dev, &addr_type, arp->ar_op, 900 sip, tip, sha, tha); 901 } 902 903 if (arp_accept(in_dev, sip)) { 904 /* Unsolicited ARP is not accepted by default. 905 It is possible, that this option should be enabled for some 906 devices (strip is candidate) 907 */ 908 if (!n && 909 (is_garp || 910 (arp->ar_op == htons(ARPOP_REPLY) && 911 (addr_type == RTN_UNICAST || 912 (addr_type < 0 && 913 /* postpone calculation to as late as possible */ 914 inet_addr_type_dev_table(net, dev, sip) == RTN_UNICAST))))) { 915 n = ipv4_neigh_lookup(dev, &sip); 916 if (!n) { 917 n = ipv4_neigh_create(dev, &sip); 918 if (IS_ERR(n)) 919 n = NULL; 920 } 921 } 922 } 923 924 if (n) { 925 int state = NUD_REACHABLE; 926 int override; 927 928 /* If several different ARP replies follows back-to-back, 929 use the FIRST one. It is possible, if several proxy 930 agents are active. Taking the first reply prevents 931 arp trashing and chooses the fastest router. 932 */ 933 override = time_after(jiffies, 934 n->updated + 935 NEIGH_VAR(n->parms, LOCKTIME)) || 936 is_garp; 937 938 /* Broadcast replies and request packets 939 do not assert neighbour reachability. 940 */ 941 if (arp->ar_op != htons(ARPOP_REPLY) || 942 skb->pkt_type != PACKET_HOST) 943 state = NUD_STALE; 944 neigh_update(n, sha, state, 945 override ? NEIGH_UPDATE_F_OVERRIDE : 0, 0); 946 neigh_release(n); 947 } 948 949 out_consume_skb: 950 consume_skb(skb); 951 952 out_free_dst: 953 dst_release(reply_dst); 954 return NET_RX_SUCCESS; 955 956 out_free_skb: 957 kfree_skb(skb); 958 return NET_RX_DROP; 959 } 960 961 static void parp_redo(struct sk_buff *skb) 962 { 963 arp_process(dev_net(skb->dev), NULL, skb); 964 } 965 966 static int arp_is_multicast(const void *pkey) 967 { 968 return ipv4_is_multicast(*((__be32 *)pkey)); 969 } 970 971 /* 972 * Receive an arp request from the device layer. 973 */ 974 975 static int arp_rcv(struct sk_buff *skb, struct net_device *dev, 976 struct packet_type *pt, struct net_device *orig_dev) 977 { 978 enum skb_drop_reason drop_reason; 979 const struct arphdr *arp; 980 981 /* do not tweak dropwatch on an ARP we will ignore */ 982 if (dev->flags & IFF_NOARP || 983 skb->pkt_type == PACKET_OTHERHOST || 984 skb->pkt_type == PACKET_LOOPBACK) 985 goto consumeskb; 986 987 skb = skb_share_check(skb, GFP_ATOMIC); 988 if (!skb) 989 goto out_of_mem; 990 991 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */ 992 drop_reason = pskb_may_pull_reason(skb, arp_hdr_len(dev)); 993 if (drop_reason != SKB_NOT_DROPPED_YET) 994 goto freeskb; 995 996 arp = arp_hdr(skb); 997 if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4) { 998 drop_reason = SKB_DROP_REASON_NOT_SPECIFIED; 999 goto freeskb; 1000 } 1001 1002 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb)); 1003 1004 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, 1005 dev_net(dev), NULL, skb, dev, NULL, 1006 arp_process); 1007 1008 consumeskb: 1009 consume_skb(skb); 1010 return NET_RX_SUCCESS; 1011 freeskb: 1012 kfree_skb_reason(skb, drop_reason); 1013 out_of_mem: 1014 return NET_RX_DROP; 1015 } 1016 1017 /* 1018 * User level interface (ioctl) 1019 */ 1020 1021 static struct net_device *arp_req_dev_by_name(struct net *net, struct arpreq *r, 1022 bool getarp) 1023 { 1024 struct net_device *dev; 1025 1026 if (getarp) 1027 dev = dev_get_by_name_rcu(net, r->arp_dev); 1028 else 1029 dev = __dev_get_by_name(net, r->arp_dev); 1030 if (!dev) 1031 return ERR_PTR(-ENODEV); 1032 1033 /* Mmmm... It is wrong... ARPHRD_NETROM == 0 */ 1034 if (!r->arp_ha.sa_family) 1035 r->arp_ha.sa_family = dev->type; 1036 1037 if ((r->arp_flags & ATF_COM) && r->arp_ha.sa_family != dev->type) 1038 return ERR_PTR(-EINVAL); 1039 1040 return dev; 1041 } 1042 1043 static struct net_device *arp_req_dev(struct net *net, struct arpreq *r) 1044 { 1045 struct net_device *dev; 1046 struct rtable *rt; 1047 __be32 ip; 1048 1049 if (r->arp_dev[0]) 1050 return arp_req_dev_by_name(net, r, false); 1051 1052 if (r->arp_flags & ATF_PUBL) 1053 return NULL; 1054 1055 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1056 1057 rt = ip_route_output(net, ip, 0, 0, 0, RT_SCOPE_LINK); 1058 if (IS_ERR(rt)) 1059 return ERR_CAST(rt); 1060 1061 dev = rt->dst.dev; 1062 ip_rt_put(rt); 1063 1064 if (!dev) 1065 return ERR_PTR(-EINVAL); 1066 1067 return dev; 1068 } 1069 1070 /* 1071 * Set (create) an ARP cache entry. 1072 */ 1073 1074 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on) 1075 { 1076 if (!dev) { 1077 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on; 1078 return 0; 1079 } 1080 if (__in_dev_get_rtnl_net(dev)) { 1081 IN_DEV_CONF_SET(__in_dev_get_rtnl_net(dev), PROXY_ARP, on); 1082 return 0; 1083 } 1084 return -ENXIO; 1085 } 1086 1087 static int arp_req_set_public(struct net *net, struct arpreq *r, 1088 struct net_device *dev) 1089 { 1090 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 1091 struct neigh_table *tbl = arp_table(net); 1092 1093 if (!dev && (r->arp_flags & ATF_COM)) { 1094 dev = dev_getbyhwaddr(net, r->arp_ha.sa_family, 1095 r->arp_ha.sa_data); 1096 if (!dev) 1097 return -ENODEV; 1098 } 1099 if (mask) { 1100 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1101 1102 return pneigh_create(tbl, &ip, dev, 0, 0, false); 1103 } 1104 1105 return arp_req_set_proxy(net, dev, 1); 1106 } 1107 1108 static int arp_req_set(struct net *net, struct arpreq *r) 1109 { 1110 struct neighbour *neigh; 1111 struct net_device *dev; 1112 __be32 ip; 1113 int err; 1114 1115 dev = arp_req_dev(net, r); 1116 if (IS_ERR(dev)) 1117 return PTR_ERR(dev); 1118 1119 if (r->arp_flags & ATF_PUBL) 1120 return arp_req_set_public(net, r, dev); 1121 1122 switch (dev->type) { 1123 #if IS_ENABLED(CONFIG_FDDI) 1124 case ARPHRD_FDDI: 1125 /* 1126 * According to RFC 1390, FDDI devices should accept ARP 1127 * hardware types of 1 (Ethernet). However, to be more 1128 * robust, we'll accept hardware types of either 1 (Ethernet) 1129 * or 6 (IEEE 802.2). 1130 */ 1131 if (r->arp_ha.sa_family != ARPHRD_FDDI && 1132 r->arp_ha.sa_family != ARPHRD_ETHER && 1133 r->arp_ha.sa_family != ARPHRD_IEEE802) 1134 return -EINVAL; 1135 break; 1136 #endif 1137 default: 1138 if (r->arp_ha.sa_family != dev->type) 1139 return -EINVAL; 1140 break; 1141 } 1142 1143 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1144 1145 neigh = ipv4_neigh_lookup(dev, &ip); 1146 if (!neigh) 1147 neigh = ipv4_neigh_create(dev, &ip); 1148 err = PTR_ERR(neigh); 1149 if (!IS_ERR(neigh)) { 1150 unsigned int state = NUD_STALE; 1151 1152 if (r->arp_flags & ATF_PERM) { 1153 r->arp_flags |= ATF_COM; 1154 state = NUD_PERMANENT; 1155 } 1156 1157 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ? 1158 r->arp_ha.sa_data : NULL, state, 1159 NEIGH_UPDATE_F_OVERRIDE | 1160 NEIGH_UPDATE_F_ADMIN, 0); 1161 neigh_release(neigh); 1162 } 1163 return err; 1164 } 1165 1166 static unsigned int arp_state_to_flags(struct neighbour *neigh) 1167 { 1168 if (neigh->nud_state&NUD_PERMANENT) 1169 return ATF_PERM | ATF_COM; 1170 else if (neigh->nud_state&NUD_VALID) 1171 return ATF_COM; 1172 else 1173 return 0; 1174 } 1175 1176 /* 1177 * Get an ARP cache entry. 1178 */ 1179 1180 static int arp_req_get(struct net *net, struct arpreq *r) 1181 { 1182 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; 1183 struct neighbour *neigh; 1184 struct net_device *dev; 1185 1186 if (!r->arp_dev[0]) 1187 return -ENODEV; 1188 1189 dev = arp_req_dev_by_name(net, r, true); 1190 if (IS_ERR(dev)) 1191 return PTR_ERR(dev); 1192 1193 neigh = ipv4_neigh_lookup(dev, &ip); 1194 if (!neigh) 1195 return -ENXIO; 1196 1197 if (READ_ONCE(neigh->nud_state) & NUD_NOARP) { 1198 neigh_release(neigh); 1199 return -ENXIO; 1200 } 1201 1202 read_lock_bh(&neigh->lock); 1203 memcpy(r->arp_ha.sa_data, neigh->ha, 1204 min(dev->addr_len, sizeof(r->arp_ha.sa_data))); 1205 r->arp_flags = arp_state_to_flags(neigh); 1206 read_unlock_bh(&neigh->lock); 1207 1208 neigh_release(neigh); 1209 1210 r->arp_ha.sa_family = dev->type; 1211 netdev_copy_name(dev, r->arp_dev); 1212 1213 return 0; 1214 } 1215 1216 int arp_invalidate(struct net_device *dev, __be32 ip, bool force) 1217 { 1218 struct neighbour *neigh; 1219 int err = -ENXIO; 1220 1221 neigh = ipv4_neigh_lookup(dev, &ip); 1222 if (neigh) { 1223 struct neigh_table *tbl = neigh->tbl; 1224 1225 if ((READ_ONCE(neigh->nud_state) & NUD_VALID) && !force) { 1226 neigh_release(neigh); 1227 return 0; 1228 } 1229 1230 if (READ_ONCE(neigh->nud_state) & ~NUD_NOARP) 1231 err = neigh_update(neigh, NULL, NUD_FAILED, 1232 NEIGH_UPDATE_F_OVERRIDE| 1233 NEIGH_UPDATE_F_ADMIN, 0); 1234 spin_lock_bh(&tbl->lock); 1235 neigh_release(neigh); 1236 neigh_remove_one(neigh); 1237 spin_unlock_bh(&tbl->lock); 1238 } 1239 1240 return err; 1241 } 1242 1243 static int arp_req_delete_public(struct net *net, struct arpreq *r, 1244 struct net_device *dev) 1245 { 1246 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 1247 struct neigh_table *tbl = arp_table(net); 1248 1249 if (mask) { 1250 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1251 1252 return pneigh_delete(tbl, &ip, dev); 1253 } 1254 1255 return arp_req_set_proxy(net, dev, 0); 1256 } 1257 1258 static int arp_req_delete(struct net *net, struct arpreq *r) 1259 { 1260 struct net_device *dev; 1261 __be32 ip; 1262 1263 dev = arp_req_dev(net, r); 1264 if (IS_ERR(dev)) 1265 return PTR_ERR(dev); 1266 1267 if (r->arp_flags & ATF_PUBL) 1268 return arp_req_delete_public(net, r, dev); 1269 1270 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1271 1272 return arp_invalidate(dev, ip, true); 1273 } 1274 1275 /* 1276 * Handle an ARP layer I/O control request. 1277 */ 1278 1279 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg) 1280 { 1281 struct arpreq r; 1282 __be32 *netmask; 1283 int err; 1284 1285 switch (cmd) { 1286 case SIOCDARP: 1287 case SIOCSARP: 1288 if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) 1289 return -EPERM; 1290 fallthrough; 1291 case SIOCGARP: 1292 err = copy_from_user(&r, arg, sizeof(struct arpreq)); 1293 if (err) 1294 return -EFAULT; 1295 r.arp_dev[IFNAMSIZ - 1] = '\0'; 1296 break; 1297 default: 1298 return -EINVAL; 1299 } 1300 1301 if (r.arp_pa.sa_family != AF_INET) 1302 return -EPFNOSUPPORT; 1303 1304 if (!(r.arp_flags & ATF_PUBL) && 1305 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB))) 1306 return -EINVAL; 1307 1308 netmask = &((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr; 1309 if (!(r.arp_flags & ATF_NETMASK)) 1310 *netmask = htonl(0xFFFFFFFFUL); 1311 else if (*netmask && *netmask != htonl(0xFFFFFFFFUL)) 1312 return -EINVAL; 1313 1314 switch (cmd) { 1315 case SIOCDARP: 1316 rtnl_net_lock(net); 1317 err = arp_req_delete(net, &r); 1318 rtnl_net_unlock(net); 1319 break; 1320 case SIOCSARP: 1321 rtnl_net_lock(net); 1322 err = arp_req_set(net, &r); 1323 rtnl_net_unlock(net); 1324 break; 1325 case SIOCGARP: 1326 rcu_read_lock(); 1327 err = arp_req_get(net, &r); 1328 rcu_read_unlock(); 1329 1330 if (!err && copy_to_user(arg, &r, sizeof(r))) 1331 err = -EFAULT; 1332 break; 1333 } 1334 1335 return err; 1336 } 1337 1338 static int arp_netdev_event(struct notifier_block *this, unsigned long event, 1339 void *ptr) 1340 { 1341 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 1342 struct netdev_notifier_change_info *change_info; 1343 struct net *net = dev_net(dev); 1344 struct in_device *in_dev; 1345 struct neigh_table *tbl; 1346 bool evict_nocarrier; 1347 1348 tbl = arp_table(net); 1349 1350 switch (event) { 1351 case NETDEV_CHANGEADDR: 1352 neigh_changeaddr(tbl, dev); 1353 rt_cache_flush(net); 1354 break; 1355 case NETDEV_CHANGE: 1356 change_info = ptr; 1357 if (change_info->flags_changed & IFF_NOARP) 1358 neigh_changeaddr(tbl, dev); 1359 1360 in_dev = __in_dev_get_rtnl(dev); 1361 if (!in_dev) 1362 evict_nocarrier = true; 1363 else 1364 evict_nocarrier = IN_DEV_ARP_EVICT_NOCARRIER(in_dev); 1365 1366 if (evict_nocarrier && !netif_carrier_ok(dev)) 1367 neigh_carrier_down(tbl, dev); 1368 break; 1369 default: 1370 break; 1371 } 1372 1373 return NOTIFY_DONE; 1374 } 1375 1376 static struct notifier_block arp_netdev_notifier = { 1377 .notifier_call = arp_netdev_event, 1378 }; 1379 1380 /* Note, that it is not on notifier chain. 1381 It is necessary, that this routine was called after route cache will be 1382 flushed. 1383 */ 1384 void arp_ifdown(struct net_device *dev) 1385 { 1386 struct neigh_table *tbl = arp_table(dev_net(dev)); 1387 1388 neigh_ifdown(tbl, dev); 1389 } 1390 1391 1392 /* 1393 * Called once on startup. 1394 */ 1395 1396 static struct packet_type arp_packet_type __read_mostly = { 1397 .type = cpu_to_be16(ETH_P_ARP), 1398 .func = arp_rcv, 1399 }; 1400 1401 #ifdef CONFIG_PROC_FS 1402 #if IS_ENABLED(CONFIG_AX25) 1403 1404 /* 1405 * ax25 -> ASCII conversion 1406 */ 1407 static void ax2asc2(ax25_address *a, char *buf) 1408 { 1409 char c, *s; 1410 int n; 1411 1412 for (n = 0, s = buf; n < 6; n++) { 1413 c = (a->ax25_call[n] >> 1) & 0x7F; 1414 1415 if (c != ' ') 1416 *s++ = c; 1417 } 1418 1419 *s++ = '-'; 1420 n = (a->ax25_call[6] >> 1) & 0x0F; 1421 if (n > 9) { 1422 *s++ = '1'; 1423 n -= 10; 1424 } 1425 1426 *s++ = n + '0'; 1427 *s++ = '\0'; 1428 1429 if (*buf == '\0' || *buf == '-') { 1430 buf[0] = '*'; 1431 buf[1] = '\0'; 1432 } 1433 } 1434 #endif /* CONFIG_AX25 */ 1435 1436 #define HBUFFERLEN 30 1437 1438 static void arp_format_neigh_entry(struct seq_file *seq, 1439 struct neighbour *n) 1440 { 1441 char hbuffer[HBUFFERLEN]; 1442 int k, j; 1443 char tbuf[16]; 1444 struct net_device *dev = n->dev; 1445 int hatype = dev->type; 1446 1447 read_lock(&n->lock); 1448 /* Convert hardware address to XX:XX:XX:XX ... form. */ 1449 #if IS_ENABLED(CONFIG_AX25) 1450 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM) 1451 ax2asc2((ax25_address *)n->ha, hbuffer); 1452 else { 1453 #endif 1454 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) { 1455 hbuffer[k++] = hex_asc_hi(n->ha[j]); 1456 hbuffer[k++] = hex_asc_lo(n->ha[j]); 1457 hbuffer[k++] = ':'; 1458 } 1459 if (k != 0) 1460 --k; 1461 hbuffer[k] = 0; 1462 #if IS_ENABLED(CONFIG_AX25) 1463 } 1464 #endif 1465 sprintf(tbuf, "%pI4", n->primary_key); 1466 seq_printf(seq, "%-16s 0x%-10x0x%-10x%-17s * %s\n", 1467 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name); 1468 read_unlock(&n->lock); 1469 } 1470 1471 static void arp_format_pneigh_entry(struct seq_file *seq, 1472 struct pneigh_entry *n) 1473 { 1474 struct net_device *dev = n->dev; 1475 int hatype = dev ? dev->type : 0; 1476 char tbuf[16]; 1477 1478 sprintf(tbuf, "%pI4", n->key); 1479 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n", 1480 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00", 1481 dev ? dev->name : "*"); 1482 } 1483 1484 static int arp_seq_show(struct seq_file *seq, void *v) 1485 { 1486 if (v == SEQ_START_TOKEN) { 1487 seq_puts(seq, "IP address HW type Flags " 1488 "HW address Mask Device\n"); 1489 } else { 1490 struct neigh_seq_state *state = seq->private; 1491 1492 if (state->flags & NEIGH_SEQ_IS_PNEIGH) 1493 arp_format_pneigh_entry(seq, v); 1494 else 1495 arp_format_neigh_entry(seq, v); 1496 } 1497 1498 return 0; 1499 } 1500 1501 static void *arp_seq_start(struct seq_file *seq, loff_t *pos) 1502 { 1503 struct neigh_table *tbl = arp_table(seq_file_net(seq)); 1504 1505 /* Don't want to confuse "arp -a" w/ magic entries, 1506 * so we tell the generic iterator to skip NUD_NOARP. 1507 */ 1508 return neigh_seq_start(seq, pos, tbl, NEIGH_SEQ_SKIP_NOARP); 1509 } 1510 1511 static const struct seq_operations arp_seq_ops = { 1512 .start = arp_seq_start, 1513 .next = neigh_seq_next, 1514 .stop = neigh_seq_stop, 1515 .show = arp_seq_show, 1516 }; 1517 #endif /* CONFIG_PROC_FS */ 1518 1519 static int __net_init arp_net_init(struct net *net) 1520 { 1521 int err; 1522 1523 err = neigh_table_register(net, &arp_tbl, NEIGH_ARP_TABLE); 1524 if (err) 1525 goto err; 1526 1527 #ifdef CONFIG_PROC_FS 1528 #ifdef CONFIG_SYSCTL 1529 err = neigh_sysctl_register(NULL, &arp_table(net)->parms, NULL); 1530 if (err) 1531 goto err_sysctl; 1532 #endif 1533 1534 if (!proc_create_net("arp", 0444, net->proc_net, &arp_seq_ops, 1535 sizeof(struct neigh_seq_state))) { 1536 err = -ENOMEM; 1537 goto err_proc_create; 1538 } 1539 #endif 1540 1541 return 0; 1542 1543 #ifdef CONFIG_PROC_FS 1544 err_proc_create: 1545 #ifdef CONFIG_SYSCTL 1546 neigh_sysctl_unregister(&arp_table(net)->parms); 1547 err_sysctl: 1548 #endif 1549 neigh_table_unregister(net, NEIGH_ARP_TABLE); 1550 #endif 1551 err: 1552 return err; 1553 } 1554 1555 static void __net_exit arp_net_exit(struct net *net) 1556 { 1557 remove_proc_entry("arp", net->proc_net); 1558 #ifdef CONFIG_SYSCTL 1559 neigh_sysctl_unregister(&arp_table(net)->parms); 1560 #endif 1561 neigh_table_unregister(net, NEIGH_ARP_TABLE); 1562 } 1563 1564 static struct pernet_operations arp_net_ops = { 1565 .init = arp_net_init, 1566 .exit = arp_net_exit, 1567 }; 1568 1569 void __init arp_init(void) 1570 { 1571 if (register_pernet_subsys(&arp_net_ops)) 1572 panic("Cannot allocate arp table\n"); 1573 1574 dev_add_pack(&arp_packet_type); 1575 register_netdevice_notifier(&arp_netdev_notifier); 1576 } 1577