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 rcu_read_lock(); 663 /* Send it off, maybe filter it using firewalling first. */ 664 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, 665 dev_net_rcu(skb->dev), NULL, skb, NULL, skb->dev, 666 arp_xmit_finish); 667 rcu_read_unlock(); 668 } 669 EXPORT_SYMBOL(arp_xmit); 670 671 static bool arp_is_garp(struct net *net, struct net_device *dev, 672 int *addr_type, __be16 ar_op, 673 __be32 sip, __be32 tip, 674 unsigned char *sha, unsigned char *tha) 675 { 676 bool is_garp = tip == sip; 677 678 /* Gratuitous ARP _replies_ also require target hwaddr to be 679 * the same as source. 680 */ 681 if (is_garp && ar_op == htons(ARPOP_REPLY)) 682 is_garp = 683 /* IPv4 over IEEE 1394 doesn't provide target 684 * hardware address field in its ARP payload. 685 */ 686 tha && 687 !memcmp(tha, sha, dev->addr_len); 688 689 if (is_garp) { 690 *addr_type = inet_addr_type_dev_table(net, dev, sip); 691 if (*addr_type != RTN_UNICAST) 692 is_garp = false; 693 } 694 return is_garp; 695 } 696 697 /* 698 * Process an arp request. 699 */ 700 701 static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb) 702 { 703 struct net_device *dev = skb->dev; 704 struct in_device *in_dev = __in_dev_get_rcu(dev); 705 struct arphdr *arp; 706 unsigned char *arp_ptr; 707 struct rtable *rt; 708 unsigned char *sha; 709 unsigned char *tha = NULL; 710 __be32 sip, tip; 711 u16 dev_type = dev->type; 712 int addr_type; 713 struct neighbour *n; 714 struct dst_entry *reply_dst = NULL; 715 bool is_garp = false; 716 717 /* arp_rcv below verifies the ARP header and verifies the device 718 * is ARP'able. 719 */ 720 721 if (!in_dev) 722 goto out_free_skb; 723 724 arp = arp_hdr(skb); 725 726 switch (dev_type) { 727 default: 728 if (arp->ar_pro != htons(ETH_P_IP) || 729 htons(dev_type) != arp->ar_hrd) 730 goto out_free_skb; 731 break; 732 case ARPHRD_ETHER: 733 case ARPHRD_FDDI: 734 case ARPHRD_IEEE802: 735 /* 736 * ETHERNET, and Fibre Channel (which are IEEE 802 737 * devices, according to RFC 2625) devices will accept ARP 738 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2). 739 * This is the case also of FDDI, where the RFC 1390 says that 740 * FDDI devices should accept ARP hardware of (1) Ethernet, 741 * however, to be more robust, we'll accept both 1 (Ethernet) 742 * or 6 (IEEE 802.2) 743 */ 744 if ((arp->ar_hrd != htons(ARPHRD_ETHER) && 745 arp->ar_hrd != htons(ARPHRD_IEEE802)) || 746 arp->ar_pro != htons(ETH_P_IP)) 747 goto out_free_skb; 748 break; 749 case ARPHRD_AX25: 750 if (arp->ar_pro != htons(AX25_P_IP) || 751 arp->ar_hrd != htons(ARPHRD_AX25)) 752 goto out_free_skb; 753 break; 754 case ARPHRD_NETROM: 755 if (arp->ar_pro != htons(AX25_P_IP) || 756 arp->ar_hrd != htons(ARPHRD_NETROM)) 757 goto out_free_skb; 758 break; 759 } 760 761 /* Understand only these message types */ 762 763 if (arp->ar_op != htons(ARPOP_REPLY) && 764 arp->ar_op != htons(ARPOP_REQUEST)) 765 goto out_free_skb; 766 767 /* 768 * Extract fields 769 */ 770 arp_ptr = (unsigned char *)(arp + 1); 771 sha = arp_ptr; 772 arp_ptr += dev->addr_len; 773 memcpy(&sip, arp_ptr, 4); 774 arp_ptr += 4; 775 switch (dev_type) { 776 #if IS_ENABLED(CONFIG_FIREWIRE_NET) 777 case ARPHRD_IEEE1394: 778 break; 779 #endif 780 default: 781 tha = arp_ptr; 782 arp_ptr += dev->addr_len; 783 } 784 memcpy(&tip, arp_ptr, 4); 785 /* 786 * Check for bad requests for 127.x.x.x and requests for multicast 787 * addresses. If this is one such, delete it. 788 */ 789 if (ipv4_is_multicast(tip) || 790 (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip))) 791 goto out_free_skb; 792 793 /* 794 * For some 802.11 wireless deployments (and possibly other networks), 795 * there will be an ARP proxy and gratuitous ARP frames are attacks 796 * and thus should not be accepted. 797 */ 798 if (sip == tip && IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP)) 799 goto out_free_skb; 800 801 /* 802 * Special case: We must set Frame Relay source Q.922 address 803 */ 804 if (dev_type == ARPHRD_DLCI) 805 sha = dev->broadcast; 806 807 /* 808 * Process entry. The idea here is we want to send a reply if it is a 809 * request for us or if it is a request for someone else that we hold 810 * a proxy for. We want to add an entry to our cache if it is a reply 811 * to us or if it is a request for our address. 812 * (The assumption for this last is that if someone is requesting our 813 * address, they are probably intending to talk to us, so it saves time 814 * if we cache their address. Their address is also probably not in 815 * our cache, since ours is not in their cache.) 816 * 817 * Putting this another way, we only care about replies if they are to 818 * us, in which case we add them to the cache. For requests, we care 819 * about those for us and those for our proxies. We reply to both, 820 * and in the case of requests for us we add the requester to the arp 821 * cache. 822 */ 823 824 if (arp->ar_op == htons(ARPOP_REQUEST) && skb_metadata_dst(skb)) 825 reply_dst = (struct dst_entry *) 826 iptunnel_metadata_reply(skb_metadata_dst(skb), 827 GFP_ATOMIC); 828 829 /* Special case: IPv4 duplicate address detection packet (RFC2131) */ 830 if (sip == 0) { 831 if (arp->ar_op == htons(ARPOP_REQUEST) && 832 inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL && 833 !arp_ignore(in_dev, sip, tip)) 834 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, 835 sha, dev->dev_addr, sha, reply_dst); 836 goto out_consume_skb; 837 } 838 839 if (arp->ar_op == htons(ARPOP_REQUEST) && 840 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) { 841 842 rt = skb_rtable(skb); 843 addr_type = rt->rt_type; 844 845 if (addr_type == RTN_LOCAL) { 846 int dont_send; 847 848 dont_send = arp_ignore(in_dev, sip, tip); 849 if (!dont_send && IN_DEV_ARPFILTER(in_dev)) 850 dont_send = arp_filter(sip, tip, dev); 851 if (!dont_send) { 852 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 853 if (n) { 854 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, 855 sip, dev, tip, sha, 856 dev->dev_addr, sha, 857 reply_dst); 858 neigh_release(n); 859 } 860 } 861 goto out_consume_skb; 862 } else if (IN_DEV_FORWARD(in_dev)) { 863 if (addr_type == RTN_UNICAST && 864 (arp_fwd_proxy(in_dev, dev, rt) || 865 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) || 866 (rt->dst.dev != dev && 867 pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) { 868 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 869 if (n) 870 neigh_release(n); 871 872 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED || 873 skb->pkt_type == PACKET_HOST || 874 NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) { 875 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, 876 sip, dev, tip, sha, 877 dev->dev_addr, sha, 878 reply_dst); 879 } else { 880 pneigh_enqueue(&arp_tbl, 881 in_dev->arp_parms, skb); 882 goto out_free_dst; 883 } 884 goto out_consume_skb; 885 } 886 } 887 } 888 889 /* Update our ARP tables */ 890 891 n = __neigh_lookup(&arp_tbl, &sip, dev, 0); 892 893 addr_type = -1; 894 if (n || arp_accept(in_dev, sip)) { 895 is_garp = arp_is_garp(net, dev, &addr_type, arp->ar_op, 896 sip, tip, sha, tha); 897 } 898 899 if (arp_accept(in_dev, sip)) { 900 /* Unsolicited ARP is not accepted by default. 901 It is possible, that this option should be enabled for some 902 devices (strip is candidate) 903 */ 904 if (!n && 905 (is_garp || 906 (arp->ar_op == htons(ARPOP_REPLY) && 907 (addr_type == RTN_UNICAST || 908 (addr_type < 0 && 909 /* postpone calculation to as late as possible */ 910 inet_addr_type_dev_table(net, dev, sip) == 911 RTN_UNICAST))))) 912 n = __neigh_lookup(&arp_tbl, &sip, dev, 1); 913 } 914 915 if (n) { 916 int state = NUD_REACHABLE; 917 int override; 918 919 /* If several different ARP replies follows back-to-back, 920 use the FIRST one. It is possible, if several proxy 921 agents are active. Taking the first reply prevents 922 arp trashing and chooses the fastest router. 923 */ 924 override = time_after(jiffies, 925 n->updated + 926 NEIGH_VAR(n->parms, LOCKTIME)) || 927 is_garp; 928 929 /* Broadcast replies and request packets 930 do not assert neighbour reachability. 931 */ 932 if (arp->ar_op != htons(ARPOP_REPLY) || 933 skb->pkt_type != PACKET_HOST) 934 state = NUD_STALE; 935 neigh_update(n, sha, state, 936 override ? NEIGH_UPDATE_F_OVERRIDE : 0, 0); 937 neigh_release(n); 938 } 939 940 out_consume_skb: 941 consume_skb(skb); 942 943 out_free_dst: 944 dst_release(reply_dst); 945 return NET_RX_SUCCESS; 946 947 out_free_skb: 948 kfree_skb(skb); 949 return NET_RX_DROP; 950 } 951 952 static void parp_redo(struct sk_buff *skb) 953 { 954 arp_process(dev_net(skb->dev), NULL, skb); 955 } 956 957 static int arp_is_multicast(const void *pkey) 958 { 959 return ipv4_is_multicast(*((__be32 *)pkey)); 960 } 961 962 /* 963 * Receive an arp request from the device layer. 964 */ 965 966 static int arp_rcv(struct sk_buff *skb, struct net_device *dev, 967 struct packet_type *pt, struct net_device *orig_dev) 968 { 969 enum skb_drop_reason drop_reason; 970 const struct arphdr *arp; 971 972 /* do not tweak dropwatch on an ARP we will ignore */ 973 if (dev->flags & IFF_NOARP || 974 skb->pkt_type == PACKET_OTHERHOST || 975 skb->pkt_type == PACKET_LOOPBACK) 976 goto consumeskb; 977 978 skb = skb_share_check(skb, GFP_ATOMIC); 979 if (!skb) 980 goto out_of_mem; 981 982 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */ 983 drop_reason = pskb_may_pull_reason(skb, arp_hdr_len(dev)); 984 if (drop_reason != SKB_NOT_DROPPED_YET) 985 goto freeskb; 986 987 arp = arp_hdr(skb); 988 if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4) { 989 drop_reason = SKB_DROP_REASON_NOT_SPECIFIED; 990 goto freeskb; 991 } 992 993 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb)); 994 995 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, 996 dev_net(dev), NULL, skb, dev, NULL, 997 arp_process); 998 999 consumeskb: 1000 consume_skb(skb); 1001 return NET_RX_SUCCESS; 1002 freeskb: 1003 kfree_skb_reason(skb, drop_reason); 1004 out_of_mem: 1005 return NET_RX_DROP; 1006 } 1007 1008 /* 1009 * User level interface (ioctl) 1010 */ 1011 1012 static struct net_device *arp_req_dev_by_name(struct net *net, struct arpreq *r, 1013 bool getarp) 1014 { 1015 struct net_device *dev; 1016 1017 if (getarp) 1018 dev = dev_get_by_name_rcu(net, r->arp_dev); 1019 else 1020 dev = __dev_get_by_name(net, r->arp_dev); 1021 if (!dev) 1022 return ERR_PTR(-ENODEV); 1023 1024 /* Mmmm... It is wrong... ARPHRD_NETROM == 0 */ 1025 if (!r->arp_ha.sa_family) 1026 r->arp_ha.sa_family = dev->type; 1027 1028 if ((r->arp_flags & ATF_COM) && r->arp_ha.sa_family != dev->type) 1029 return ERR_PTR(-EINVAL); 1030 1031 return dev; 1032 } 1033 1034 static struct net_device *arp_req_dev(struct net *net, struct arpreq *r) 1035 { 1036 struct net_device *dev; 1037 struct rtable *rt; 1038 __be32 ip; 1039 1040 if (r->arp_dev[0]) 1041 return arp_req_dev_by_name(net, r, false); 1042 1043 if (r->arp_flags & ATF_PUBL) 1044 return NULL; 1045 1046 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1047 1048 rt = ip_route_output(net, ip, 0, 0, 0, RT_SCOPE_LINK); 1049 if (IS_ERR(rt)) 1050 return ERR_CAST(rt); 1051 1052 dev = rt->dst.dev; 1053 ip_rt_put(rt); 1054 1055 if (!dev) 1056 return ERR_PTR(-EINVAL); 1057 1058 return dev; 1059 } 1060 1061 /* 1062 * Set (create) an ARP cache entry. 1063 */ 1064 1065 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on) 1066 { 1067 if (!dev) { 1068 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on; 1069 return 0; 1070 } 1071 if (__in_dev_get_rtnl_net(dev)) { 1072 IN_DEV_CONF_SET(__in_dev_get_rtnl_net(dev), PROXY_ARP, on); 1073 return 0; 1074 } 1075 return -ENXIO; 1076 } 1077 1078 static int arp_req_set_public(struct net *net, struct arpreq *r, 1079 struct net_device *dev) 1080 { 1081 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 1082 1083 if (!dev && (r->arp_flags & ATF_COM)) { 1084 dev = dev_getbyhwaddr(net, r->arp_ha.sa_family, 1085 r->arp_ha.sa_data); 1086 if (!dev) 1087 return -ENODEV; 1088 } 1089 if (mask) { 1090 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1091 1092 if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1)) 1093 return -ENOBUFS; 1094 return 0; 1095 } 1096 1097 return arp_req_set_proxy(net, dev, 1); 1098 } 1099 1100 static int arp_req_set(struct net *net, struct arpreq *r) 1101 { 1102 struct neighbour *neigh; 1103 struct net_device *dev; 1104 __be32 ip; 1105 int err; 1106 1107 dev = arp_req_dev(net, r); 1108 if (IS_ERR(dev)) 1109 return PTR_ERR(dev); 1110 1111 if (r->arp_flags & ATF_PUBL) 1112 return arp_req_set_public(net, r, dev); 1113 1114 switch (dev->type) { 1115 #if IS_ENABLED(CONFIG_FDDI) 1116 case ARPHRD_FDDI: 1117 /* 1118 * According to RFC 1390, FDDI devices should accept ARP 1119 * hardware types of 1 (Ethernet). However, to be more 1120 * robust, we'll accept hardware types of either 1 (Ethernet) 1121 * or 6 (IEEE 802.2). 1122 */ 1123 if (r->arp_ha.sa_family != ARPHRD_FDDI && 1124 r->arp_ha.sa_family != ARPHRD_ETHER && 1125 r->arp_ha.sa_family != ARPHRD_IEEE802) 1126 return -EINVAL; 1127 break; 1128 #endif 1129 default: 1130 if (r->arp_ha.sa_family != dev->type) 1131 return -EINVAL; 1132 break; 1133 } 1134 1135 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1136 1137 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev); 1138 err = PTR_ERR(neigh); 1139 if (!IS_ERR(neigh)) { 1140 unsigned int state = NUD_STALE; 1141 1142 if (r->arp_flags & ATF_PERM) { 1143 r->arp_flags |= ATF_COM; 1144 state = NUD_PERMANENT; 1145 } 1146 1147 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ? 1148 r->arp_ha.sa_data : NULL, state, 1149 NEIGH_UPDATE_F_OVERRIDE | 1150 NEIGH_UPDATE_F_ADMIN, 0); 1151 neigh_release(neigh); 1152 } 1153 return err; 1154 } 1155 1156 static unsigned int arp_state_to_flags(struct neighbour *neigh) 1157 { 1158 if (neigh->nud_state&NUD_PERMANENT) 1159 return ATF_PERM | ATF_COM; 1160 else if (neigh->nud_state&NUD_VALID) 1161 return ATF_COM; 1162 else 1163 return 0; 1164 } 1165 1166 /* 1167 * Get an ARP cache entry. 1168 */ 1169 1170 static int arp_req_get(struct net *net, struct arpreq *r) 1171 { 1172 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; 1173 struct neighbour *neigh; 1174 struct net_device *dev; 1175 1176 if (!r->arp_dev[0]) 1177 return -ENODEV; 1178 1179 dev = arp_req_dev_by_name(net, r, true); 1180 if (IS_ERR(dev)) 1181 return PTR_ERR(dev); 1182 1183 neigh = neigh_lookup(&arp_tbl, &ip, dev); 1184 if (!neigh) 1185 return -ENXIO; 1186 1187 if (READ_ONCE(neigh->nud_state) & NUD_NOARP) { 1188 neigh_release(neigh); 1189 return -ENXIO; 1190 } 1191 1192 read_lock_bh(&neigh->lock); 1193 memcpy(r->arp_ha.sa_data, neigh->ha, 1194 min(dev->addr_len, sizeof(r->arp_ha.sa_data_min))); 1195 r->arp_flags = arp_state_to_flags(neigh); 1196 read_unlock_bh(&neigh->lock); 1197 1198 neigh_release(neigh); 1199 1200 r->arp_ha.sa_family = dev->type; 1201 netdev_copy_name(dev, r->arp_dev); 1202 1203 return 0; 1204 } 1205 1206 int arp_invalidate(struct net_device *dev, __be32 ip, bool force) 1207 { 1208 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev); 1209 int err = -ENXIO; 1210 struct neigh_table *tbl = &arp_tbl; 1211 1212 if (neigh) { 1213 if ((READ_ONCE(neigh->nud_state) & NUD_VALID) && !force) { 1214 neigh_release(neigh); 1215 return 0; 1216 } 1217 1218 if (READ_ONCE(neigh->nud_state) & ~NUD_NOARP) 1219 err = neigh_update(neigh, NULL, NUD_FAILED, 1220 NEIGH_UPDATE_F_OVERRIDE| 1221 NEIGH_UPDATE_F_ADMIN, 0); 1222 write_lock_bh(&tbl->lock); 1223 neigh_release(neigh); 1224 neigh_remove_one(neigh); 1225 write_unlock_bh(&tbl->lock); 1226 } 1227 1228 return err; 1229 } 1230 1231 static int arp_req_delete_public(struct net *net, struct arpreq *r, 1232 struct net_device *dev) 1233 { 1234 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 1235 1236 if (mask) { 1237 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1238 1239 return pneigh_delete(&arp_tbl, net, &ip, dev); 1240 } 1241 1242 return arp_req_set_proxy(net, dev, 0); 1243 } 1244 1245 static int arp_req_delete(struct net *net, struct arpreq *r) 1246 { 1247 struct net_device *dev; 1248 __be32 ip; 1249 1250 dev = arp_req_dev(net, r); 1251 if (IS_ERR(dev)) 1252 return PTR_ERR(dev); 1253 1254 if (r->arp_flags & ATF_PUBL) 1255 return arp_req_delete_public(net, r, dev); 1256 1257 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1258 1259 return arp_invalidate(dev, ip, true); 1260 } 1261 1262 /* 1263 * Handle an ARP layer I/O control request. 1264 */ 1265 1266 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg) 1267 { 1268 struct arpreq r; 1269 __be32 *netmask; 1270 int err; 1271 1272 switch (cmd) { 1273 case SIOCDARP: 1274 case SIOCSARP: 1275 if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) 1276 return -EPERM; 1277 fallthrough; 1278 case SIOCGARP: 1279 err = copy_from_user(&r, arg, sizeof(struct arpreq)); 1280 if (err) 1281 return -EFAULT; 1282 break; 1283 default: 1284 return -EINVAL; 1285 } 1286 1287 if (r.arp_pa.sa_family != AF_INET) 1288 return -EPFNOSUPPORT; 1289 1290 if (!(r.arp_flags & ATF_PUBL) && 1291 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB))) 1292 return -EINVAL; 1293 1294 netmask = &((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr; 1295 if (!(r.arp_flags & ATF_NETMASK)) 1296 *netmask = htonl(0xFFFFFFFFUL); 1297 else if (*netmask && *netmask != htonl(0xFFFFFFFFUL)) 1298 return -EINVAL; 1299 1300 switch (cmd) { 1301 case SIOCDARP: 1302 rtnl_net_lock(net); 1303 err = arp_req_delete(net, &r); 1304 rtnl_net_unlock(net); 1305 break; 1306 case SIOCSARP: 1307 rtnl_net_lock(net); 1308 err = arp_req_set(net, &r); 1309 rtnl_net_unlock(net); 1310 break; 1311 case SIOCGARP: 1312 rcu_read_lock(); 1313 err = arp_req_get(net, &r); 1314 rcu_read_unlock(); 1315 1316 if (!err && copy_to_user(arg, &r, sizeof(r))) 1317 err = -EFAULT; 1318 break; 1319 } 1320 1321 return err; 1322 } 1323 1324 static int arp_netdev_event(struct notifier_block *this, unsigned long event, 1325 void *ptr) 1326 { 1327 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 1328 struct netdev_notifier_change_info *change_info; 1329 struct in_device *in_dev; 1330 bool evict_nocarrier; 1331 1332 switch (event) { 1333 case NETDEV_CHANGEADDR: 1334 neigh_changeaddr(&arp_tbl, dev); 1335 rt_cache_flush(dev_net(dev)); 1336 break; 1337 case NETDEV_CHANGE: 1338 change_info = ptr; 1339 if (change_info->flags_changed & IFF_NOARP) 1340 neigh_changeaddr(&arp_tbl, dev); 1341 1342 in_dev = __in_dev_get_rtnl(dev); 1343 if (!in_dev) 1344 evict_nocarrier = true; 1345 else 1346 evict_nocarrier = IN_DEV_ARP_EVICT_NOCARRIER(in_dev); 1347 1348 if (evict_nocarrier && !netif_carrier_ok(dev)) 1349 neigh_carrier_down(&arp_tbl, dev); 1350 break; 1351 default: 1352 break; 1353 } 1354 1355 return NOTIFY_DONE; 1356 } 1357 1358 static struct notifier_block arp_netdev_notifier = { 1359 .notifier_call = arp_netdev_event, 1360 }; 1361 1362 /* Note, that it is not on notifier chain. 1363 It is necessary, that this routine was called after route cache will be 1364 flushed. 1365 */ 1366 void arp_ifdown(struct net_device *dev) 1367 { 1368 neigh_ifdown(&arp_tbl, dev); 1369 } 1370 1371 1372 /* 1373 * Called once on startup. 1374 */ 1375 1376 static struct packet_type arp_packet_type __read_mostly = { 1377 .type = cpu_to_be16(ETH_P_ARP), 1378 .func = arp_rcv, 1379 }; 1380 1381 #ifdef CONFIG_PROC_FS 1382 #if IS_ENABLED(CONFIG_AX25) 1383 1384 /* 1385 * ax25 -> ASCII conversion 1386 */ 1387 static void ax2asc2(ax25_address *a, char *buf) 1388 { 1389 char c, *s; 1390 int n; 1391 1392 for (n = 0, s = buf; n < 6; n++) { 1393 c = (a->ax25_call[n] >> 1) & 0x7F; 1394 1395 if (c != ' ') 1396 *s++ = c; 1397 } 1398 1399 *s++ = '-'; 1400 n = (a->ax25_call[6] >> 1) & 0x0F; 1401 if (n > 9) { 1402 *s++ = '1'; 1403 n -= 10; 1404 } 1405 1406 *s++ = n + '0'; 1407 *s++ = '\0'; 1408 1409 if (*buf == '\0' || *buf == '-') { 1410 buf[0] = '*'; 1411 buf[1] = '\0'; 1412 } 1413 } 1414 #endif /* CONFIG_AX25 */ 1415 1416 #define HBUFFERLEN 30 1417 1418 static void arp_format_neigh_entry(struct seq_file *seq, 1419 struct neighbour *n) 1420 { 1421 char hbuffer[HBUFFERLEN]; 1422 int k, j; 1423 char tbuf[16]; 1424 struct net_device *dev = n->dev; 1425 int hatype = dev->type; 1426 1427 read_lock(&n->lock); 1428 /* Convert hardware address to XX:XX:XX:XX ... form. */ 1429 #if IS_ENABLED(CONFIG_AX25) 1430 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM) 1431 ax2asc2((ax25_address *)n->ha, hbuffer); 1432 else { 1433 #endif 1434 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) { 1435 hbuffer[k++] = hex_asc_hi(n->ha[j]); 1436 hbuffer[k++] = hex_asc_lo(n->ha[j]); 1437 hbuffer[k++] = ':'; 1438 } 1439 if (k != 0) 1440 --k; 1441 hbuffer[k] = 0; 1442 #if IS_ENABLED(CONFIG_AX25) 1443 } 1444 #endif 1445 sprintf(tbuf, "%pI4", n->primary_key); 1446 seq_printf(seq, "%-16s 0x%-10x0x%-10x%-17s * %s\n", 1447 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name); 1448 read_unlock(&n->lock); 1449 } 1450 1451 static void arp_format_pneigh_entry(struct seq_file *seq, 1452 struct pneigh_entry *n) 1453 { 1454 struct net_device *dev = n->dev; 1455 int hatype = dev ? dev->type : 0; 1456 char tbuf[16]; 1457 1458 sprintf(tbuf, "%pI4", n->key); 1459 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n", 1460 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00", 1461 dev ? dev->name : "*"); 1462 } 1463 1464 static int arp_seq_show(struct seq_file *seq, void *v) 1465 { 1466 if (v == SEQ_START_TOKEN) { 1467 seq_puts(seq, "IP address HW type Flags " 1468 "HW address Mask Device\n"); 1469 } else { 1470 struct neigh_seq_state *state = seq->private; 1471 1472 if (state->flags & NEIGH_SEQ_IS_PNEIGH) 1473 arp_format_pneigh_entry(seq, v); 1474 else 1475 arp_format_neigh_entry(seq, v); 1476 } 1477 1478 return 0; 1479 } 1480 1481 static void *arp_seq_start(struct seq_file *seq, loff_t *pos) 1482 { 1483 /* Don't want to confuse "arp -a" w/ magic entries, 1484 * so we tell the generic iterator to skip NUD_NOARP. 1485 */ 1486 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP); 1487 } 1488 1489 static const struct seq_operations arp_seq_ops = { 1490 .start = arp_seq_start, 1491 .next = neigh_seq_next, 1492 .stop = neigh_seq_stop, 1493 .show = arp_seq_show, 1494 }; 1495 #endif /* CONFIG_PROC_FS */ 1496 1497 static int __net_init arp_net_init(struct net *net) 1498 { 1499 if (!proc_create_net("arp", 0444, net->proc_net, &arp_seq_ops, 1500 sizeof(struct neigh_seq_state))) 1501 return -ENOMEM; 1502 return 0; 1503 } 1504 1505 static void __net_exit arp_net_exit(struct net *net) 1506 { 1507 remove_proc_entry("arp", net->proc_net); 1508 } 1509 1510 static struct pernet_operations arp_net_ops = { 1511 .init = arp_net_init, 1512 .exit = arp_net_exit, 1513 }; 1514 1515 void __init arp_init(void) 1516 { 1517 neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl); 1518 1519 dev_add_pack(&arp_packet_type); 1520 register_pernet_subsys(&arp_net_ops); 1521 #ifdef CONFIG_SYSCTL 1522 neigh_sysctl_register(NULL, &arp_tbl.parms, NULL); 1523 #endif 1524 register_netdevice_notifier(&arp_netdev_notifier); 1525 } 1526