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 if (IS_ERR(rt)) 461 return 1; 462 if (rt->dst.dev != dev) { 463 __NET_INC_STATS(net, LINUX_MIB_ARPFILTER); 464 flag = 1; 465 } 466 ip_rt_put(rt); 467 return flag; 468 } 469 470 /* 471 * Check if we can use proxy ARP for this path 472 */ 473 static inline int arp_fwd_proxy(struct in_device *in_dev, 474 struct net_device *dev, struct rtable *rt) 475 { 476 struct in_device *out_dev; 477 int imi, omi = -1; 478 479 if (rt->dst.dev == dev) 480 return 0; 481 482 if (!IN_DEV_PROXY_ARP(in_dev)) 483 return 0; 484 imi = IN_DEV_MEDIUM_ID(in_dev); 485 if (imi == 0) 486 return 1; 487 if (imi == -1) 488 return 0; 489 490 /* place to check for proxy_arp for routes */ 491 492 out_dev = __in_dev_get_rcu(rt->dst.dev); 493 if (out_dev) 494 omi = IN_DEV_MEDIUM_ID(out_dev); 495 496 return omi != imi && omi != -1; 497 } 498 499 /* 500 * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev) 501 * 502 * RFC3069 supports proxy arp replies back to the same interface. This 503 * is done to support (ethernet) switch features, like RFC 3069, where 504 * the individual ports are not allowed to communicate with each 505 * other, BUT they are allowed to talk to the upstream router. As 506 * described in RFC 3069, it is possible to allow these hosts to 507 * communicate through the upstream router, by proxy_arp'ing. 508 * 509 * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation" 510 * 511 * This technology is known by different names: 512 * In RFC 3069 it is called VLAN Aggregation. 513 * Cisco and Allied Telesyn call it Private VLAN. 514 * Hewlett-Packard call it Source-Port filtering or port-isolation. 515 * Ericsson call it MAC-Forced Forwarding (RFC Draft). 516 * 517 */ 518 static inline int arp_fwd_pvlan(struct in_device *in_dev, 519 struct net_device *dev, struct rtable *rt, 520 __be32 sip, __be32 tip) 521 { 522 /* Private VLAN is only concerned about the same ethernet segment */ 523 if (rt->dst.dev != dev) 524 return 0; 525 526 /* Don't reply on self probes (often done by windowz boxes)*/ 527 if (sip == tip) 528 return 0; 529 530 if (IN_DEV_PROXY_ARP_PVLAN(in_dev)) 531 return 1; 532 else 533 return 0; 534 } 535 536 /* 537 * Interface to link layer: send routine and receive handler. 538 */ 539 540 /* 541 * Create an arp packet. If dest_hw is not set, we create a broadcast 542 * message. 543 */ 544 struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip, 545 struct net_device *dev, __be32 src_ip, 546 const unsigned char *dest_hw, 547 const unsigned char *src_hw, 548 const unsigned char *target_hw) 549 { 550 struct sk_buff *skb; 551 struct arphdr *arp; 552 unsigned char *arp_ptr; 553 int hlen = LL_RESERVED_SPACE(dev); 554 int tlen = dev->needed_tailroom; 555 556 /* 557 * Allocate a buffer 558 */ 559 560 skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC); 561 if (!skb) 562 return NULL; 563 564 skb_reserve(skb, hlen); 565 skb_reset_network_header(skb); 566 arp = skb_put(skb, arp_hdr_len(dev)); 567 skb->dev = dev; 568 skb->protocol = htons(ETH_P_ARP); 569 if (!src_hw) 570 src_hw = dev->dev_addr; 571 if (!dest_hw) 572 dest_hw = dev->broadcast; 573 574 /* 575 * Fill the device header for the ARP frame 576 */ 577 if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0) 578 goto out; 579 580 /* 581 * Fill out the arp protocol part. 582 * 583 * The arp hardware type should match the device type, except for FDDI, 584 * which (according to RFC 1390) should always equal 1 (Ethernet). 585 */ 586 /* 587 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the 588 * DIX code for the protocol. Make these device structure fields. 589 */ 590 switch (dev->type) { 591 default: 592 arp->ar_hrd = htons(dev->type); 593 arp->ar_pro = htons(ETH_P_IP); 594 break; 595 596 #if IS_ENABLED(CONFIG_AX25) 597 case ARPHRD_AX25: 598 arp->ar_hrd = htons(ARPHRD_AX25); 599 arp->ar_pro = htons(AX25_P_IP); 600 break; 601 602 #if IS_ENABLED(CONFIG_NETROM) 603 case ARPHRD_NETROM: 604 arp->ar_hrd = htons(ARPHRD_NETROM); 605 arp->ar_pro = htons(AX25_P_IP); 606 break; 607 #endif 608 #endif 609 610 #if IS_ENABLED(CONFIG_FDDI) 611 case ARPHRD_FDDI: 612 arp->ar_hrd = htons(ARPHRD_ETHER); 613 arp->ar_pro = htons(ETH_P_IP); 614 break; 615 #endif 616 } 617 618 arp->ar_hln = dev->addr_len; 619 arp->ar_pln = 4; 620 arp->ar_op = htons(type); 621 622 arp_ptr = (unsigned char *)(arp + 1); 623 624 memcpy(arp_ptr, src_hw, dev->addr_len); 625 arp_ptr += dev->addr_len; 626 memcpy(arp_ptr, &src_ip, 4); 627 arp_ptr += 4; 628 629 switch (dev->type) { 630 #if IS_ENABLED(CONFIG_FIREWIRE_NET) 631 case ARPHRD_IEEE1394: 632 break; 633 #endif 634 default: 635 if (target_hw) 636 memcpy(arp_ptr, target_hw, dev->addr_len); 637 else 638 memset(arp_ptr, 0, dev->addr_len); 639 arp_ptr += dev->addr_len; 640 } 641 memcpy(arp_ptr, &dest_ip, 4); 642 643 return skb; 644 645 out: 646 kfree_skb(skb); 647 return NULL; 648 } 649 EXPORT_SYMBOL(arp_create); 650 651 static int arp_xmit_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 652 { 653 return dev_queue_xmit(skb); 654 } 655 656 /* 657 * Send an arp packet. 658 */ 659 void arp_xmit(struct sk_buff *skb) 660 { 661 rcu_read_lock(); 662 /* Send it off, maybe filter it using firewalling first. */ 663 NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, 664 dev_net_rcu(skb->dev), NULL, skb, NULL, skb->dev, 665 arp_xmit_finish); 666 rcu_read_unlock(); 667 } 668 EXPORT_SYMBOL(arp_xmit); 669 670 static bool arp_is_garp(struct net *net, struct net_device *dev, 671 int *addr_type, __be16 ar_op, 672 __be32 sip, __be32 tip, 673 unsigned char *sha, unsigned char *tha) 674 { 675 bool is_garp = tip == sip; 676 677 /* Gratuitous ARP _replies_ also require target hwaddr to be 678 * the same as source. 679 */ 680 if (is_garp && ar_op == htons(ARPOP_REPLY)) 681 is_garp = 682 /* IPv4 over IEEE 1394 doesn't provide target 683 * hardware address field in its ARP payload. 684 */ 685 tha && 686 !memcmp(tha, sha, dev->addr_len); 687 688 if (is_garp) { 689 *addr_type = inet_addr_type_dev_table(net, dev, sip); 690 if (*addr_type != RTN_UNICAST) 691 is_garp = false; 692 } 693 return is_garp; 694 } 695 696 /* 697 * Process an arp request. 698 */ 699 700 static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb) 701 { 702 struct net_device *dev = skb->dev; 703 struct in_device *in_dev = __in_dev_get_rcu(dev); 704 struct arphdr *arp; 705 unsigned char *arp_ptr; 706 struct rtable *rt; 707 unsigned char *sha; 708 unsigned char *tha = NULL; 709 __be32 sip, tip; 710 u16 dev_type = dev->type; 711 int addr_type; 712 struct neighbour *n; 713 struct dst_entry *reply_dst = NULL; 714 bool is_garp = false; 715 716 /* arp_rcv below verifies the ARP header and verifies the device 717 * is ARP'able. 718 */ 719 720 if (!in_dev) 721 goto out_free_skb; 722 723 arp = arp_hdr(skb); 724 725 switch (dev_type) { 726 default: 727 if (arp->ar_pro != htons(ETH_P_IP) || 728 htons(dev_type) != arp->ar_hrd) 729 goto out_free_skb; 730 break; 731 case ARPHRD_ETHER: 732 case ARPHRD_FDDI: 733 case ARPHRD_IEEE802: 734 /* 735 * ETHERNET, and Fibre Channel (which are IEEE 802 736 * devices, according to RFC 2625) devices will accept ARP 737 * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2). 738 * This is the case also of FDDI, where the RFC 1390 says that 739 * FDDI devices should accept ARP hardware of (1) Ethernet, 740 * however, to be more robust, we'll accept both 1 (Ethernet) 741 * or 6 (IEEE 802.2) 742 */ 743 if ((arp->ar_hrd != htons(ARPHRD_ETHER) && 744 arp->ar_hrd != htons(ARPHRD_IEEE802)) || 745 arp->ar_pro != htons(ETH_P_IP)) 746 goto out_free_skb; 747 break; 748 case ARPHRD_AX25: 749 if (arp->ar_pro != htons(AX25_P_IP) || 750 arp->ar_hrd != htons(ARPHRD_AX25)) 751 goto out_free_skb; 752 break; 753 case ARPHRD_NETROM: 754 if (arp->ar_pro != htons(AX25_P_IP) || 755 arp->ar_hrd != htons(ARPHRD_NETROM)) 756 goto out_free_skb; 757 break; 758 } 759 760 /* Understand only these message types */ 761 762 if (arp->ar_op != htons(ARPOP_REPLY) && 763 arp->ar_op != htons(ARPOP_REQUEST)) 764 goto out_free_skb; 765 766 /* 767 * Extract fields 768 */ 769 arp_ptr = (unsigned char *)(arp + 1); 770 sha = arp_ptr; 771 arp_ptr += dev->addr_len; 772 memcpy(&sip, arp_ptr, 4); 773 arp_ptr += 4; 774 switch (dev_type) { 775 #if IS_ENABLED(CONFIG_FIREWIRE_NET) 776 case ARPHRD_IEEE1394: 777 break; 778 #endif 779 default: 780 tha = arp_ptr; 781 arp_ptr += dev->addr_len; 782 } 783 memcpy(&tip, arp_ptr, 4); 784 /* 785 * Check for bad requests for 127.x.x.x and requests for multicast 786 * addresses. If this is one such, delete it. 787 */ 788 if (ipv4_is_multicast(tip) || 789 (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip))) 790 goto out_free_skb; 791 792 /* 793 * For some 802.11 wireless deployments (and possibly other networks), 794 * there will be an ARP proxy and gratuitous ARP frames are attacks 795 * and thus should not be accepted. 796 */ 797 if (sip == tip && IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP)) 798 goto out_free_skb; 799 800 /* 801 * Special case: We must set Frame Relay source Q.922 address 802 */ 803 if (dev_type == ARPHRD_DLCI) 804 sha = dev->broadcast; 805 806 /* 807 * Process entry. The idea here is we want to send a reply if it is a 808 * request for us or if it is a request for someone else that we hold 809 * a proxy for. We want to add an entry to our cache if it is a reply 810 * to us or if it is a request for our address. 811 * (The assumption for this last is that if someone is requesting our 812 * address, they are probably intending to talk to us, so it saves time 813 * if we cache their address. Their address is also probably not in 814 * our cache, since ours is not in their cache.) 815 * 816 * Putting this another way, we only care about replies if they are to 817 * us, in which case we add them to the cache. For requests, we care 818 * about those for us and those for our proxies. We reply to both, 819 * and in the case of requests for us we add the requester to the arp 820 * cache. 821 */ 822 823 if (arp->ar_op == htons(ARPOP_REQUEST) && skb_metadata_dst(skb)) 824 reply_dst = (struct dst_entry *) 825 iptunnel_metadata_reply(skb_metadata_dst(skb), 826 GFP_ATOMIC); 827 828 /* Special case: IPv4 duplicate address detection packet (RFC2131) */ 829 if (sip == 0) { 830 if (arp->ar_op == htons(ARPOP_REQUEST) && 831 inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL && 832 !arp_ignore(in_dev, sip, tip)) 833 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, 834 sha, dev->dev_addr, sha, reply_dst); 835 goto out_consume_skb; 836 } 837 838 if (arp->ar_op == htons(ARPOP_REQUEST) && 839 ip_route_input_noref(skb, tip, sip, 0, dev) == 0) { 840 841 rt = skb_rtable(skb); 842 addr_type = rt->rt_type; 843 844 if (addr_type == RTN_LOCAL) { 845 int dont_send; 846 847 dont_send = arp_ignore(in_dev, sip, tip); 848 if (!dont_send && IN_DEV_ARPFILTER(in_dev)) 849 dont_send = arp_filter(sip, tip, dev); 850 if (!dont_send) { 851 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 852 if (n) { 853 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, 854 sip, dev, tip, sha, 855 dev->dev_addr, sha, 856 reply_dst); 857 neigh_release(n); 858 } 859 } 860 goto out_consume_skb; 861 } else if (IN_DEV_FORWARD(in_dev)) { 862 if (addr_type == RTN_UNICAST && 863 (arp_fwd_proxy(in_dev, dev, rt) || 864 arp_fwd_pvlan(in_dev, dev, rt, sip, tip) || 865 (rt->dst.dev != dev && 866 pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) { 867 n = neigh_event_ns(&arp_tbl, sha, &sip, dev); 868 if (n) 869 neigh_release(n); 870 871 if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED || 872 skb->pkt_type == PACKET_HOST || 873 NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) { 874 arp_send_dst(ARPOP_REPLY, ETH_P_ARP, 875 sip, dev, tip, sha, 876 dev->dev_addr, sha, 877 reply_dst); 878 } else { 879 pneigh_enqueue(&arp_tbl, 880 in_dev->arp_parms, skb); 881 goto out_free_dst; 882 } 883 goto out_consume_skb; 884 } 885 } 886 } 887 888 /* Update our ARP tables */ 889 890 n = __neigh_lookup(&arp_tbl, &sip, dev, 0); 891 892 addr_type = -1; 893 if (n || arp_accept(in_dev, sip)) { 894 is_garp = arp_is_garp(net, dev, &addr_type, arp->ar_op, 895 sip, tip, sha, tha); 896 } 897 898 if (arp_accept(in_dev, sip)) { 899 /* Unsolicited ARP is not accepted by default. 900 It is possible, that this option should be enabled for some 901 devices (strip is candidate) 902 */ 903 if (!n && 904 (is_garp || 905 (arp->ar_op == htons(ARPOP_REPLY) && 906 (addr_type == RTN_UNICAST || 907 (addr_type < 0 && 908 /* postpone calculation to as late as possible */ 909 inet_addr_type_dev_table(net, dev, sip) == 910 RTN_UNICAST))))) 911 n = __neigh_lookup(&arp_tbl, &sip, dev, 1); 912 } 913 914 if (n) { 915 int state = NUD_REACHABLE; 916 int override; 917 918 /* If several different ARP replies follows back-to-back, 919 use the FIRST one. It is possible, if several proxy 920 agents are active. Taking the first reply prevents 921 arp trashing and chooses the fastest router. 922 */ 923 override = time_after(jiffies, 924 n->updated + 925 NEIGH_VAR(n->parms, LOCKTIME)) || 926 is_garp; 927 928 /* Broadcast replies and request packets 929 do not assert neighbour reachability. 930 */ 931 if (arp->ar_op != htons(ARPOP_REPLY) || 932 skb->pkt_type != PACKET_HOST) 933 state = NUD_STALE; 934 neigh_update(n, sha, state, 935 override ? NEIGH_UPDATE_F_OVERRIDE : 0, 0); 936 neigh_release(n); 937 } 938 939 out_consume_skb: 940 consume_skb(skb); 941 942 out_free_dst: 943 dst_release(reply_dst); 944 return NET_RX_SUCCESS; 945 946 out_free_skb: 947 kfree_skb(skb); 948 return NET_RX_DROP; 949 } 950 951 static void parp_redo(struct sk_buff *skb) 952 { 953 arp_process(dev_net(skb->dev), NULL, skb); 954 } 955 956 static int arp_is_multicast(const void *pkey) 957 { 958 return ipv4_is_multicast(*((__be32 *)pkey)); 959 } 960 961 /* 962 * Receive an arp request from the device layer. 963 */ 964 965 static int arp_rcv(struct sk_buff *skb, struct net_device *dev, 966 struct packet_type *pt, struct net_device *orig_dev) 967 { 968 const struct arphdr *arp; 969 970 /* do not tweak dropwatch on an ARP we will ignore */ 971 if (dev->flags & IFF_NOARP || 972 skb->pkt_type == PACKET_OTHERHOST || 973 skb->pkt_type == PACKET_LOOPBACK) 974 goto consumeskb; 975 976 skb = skb_share_check(skb, GFP_ATOMIC); 977 if (!skb) 978 goto out_of_mem; 979 980 /* ARP header, plus 2 device addresses, plus 2 IP addresses. */ 981 if (!pskb_may_pull(skb, arp_hdr_len(dev))) 982 goto freeskb; 983 984 arp = arp_hdr(skb); 985 if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4) 986 goto freeskb; 987 988 memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb)); 989 990 return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, 991 dev_net(dev), NULL, skb, dev, NULL, 992 arp_process); 993 994 consumeskb: 995 consume_skb(skb); 996 return NET_RX_SUCCESS; 997 freeskb: 998 kfree_skb(skb); 999 out_of_mem: 1000 return NET_RX_DROP; 1001 } 1002 1003 /* 1004 * User level interface (ioctl) 1005 */ 1006 1007 /* 1008 * Set (create) an ARP cache entry. 1009 */ 1010 1011 static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on) 1012 { 1013 if (!dev) { 1014 IPV4_DEVCONF_ALL(net, PROXY_ARP) = on; 1015 return 0; 1016 } 1017 if (__in_dev_get_rtnl(dev)) { 1018 IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on); 1019 return 0; 1020 } 1021 return -ENXIO; 1022 } 1023 1024 static int arp_req_set_public(struct net *net, struct arpreq *r, 1025 struct net_device *dev) 1026 { 1027 __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1028 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 1029 1030 if (mask && mask != htonl(0xFFFFFFFF)) 1031 return -EINVAL; 1032 if (!dev && (r->arp_flags & ATF_COM)) { 1033 dev = dev_getbyhwaddr(net, r->arp_ha.sa_family, 1034 r->arp_ha.sa_data); 1035 if (!dev) 1036 return -ENODEV; 1037 } 1038 if (mask) { 1039 if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1)) 1040 return -ENOBUFS; 1041 return 0; 1042 } 1043 1044 return arp_req_set_proxy(net, dev, 1); 1045 } 1046 1047 static int arp_req_set(struct net *net, struct arpreq *r, 1048 struct net_device *dev) 1049 { 1050 __be32 ip; 1051 struct neighbour *neigh; 1052 int err; 1053 1054 if (r->arp_flags & ATF_PUBL) 1055 return arp_req_set_public(net, r, dev); 1056 1057 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1058 if (r->arp_flags & ATF_PERM) 1059 r->arp_flags |= ATF_COM; 1060 if (!dev) { 1061 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0); 1062 1063 if (IS_ERR(rt)) 1064 return PTR_ERR(rt); 1065 dev = rt->dst.dev; 1066 ip_rt_put(rt); 1067 if (!dev) 1068 return -EINVAL; 1069 } 1070 switch (dev->type) { 1071 #if IS_ENABLED(CONFIG_FDDI) 1072 case ARPHRD_FDDI: 1073 /* 1074 * According to RFC 1390, FDDI devices should accept ARP 1075 * hardware types of 1 (Ethernet). However, to be more 1076 * robust, we'll accept hardware types of either 1 (Ethernet) 1077 * or 6 (IEEE 802.2). 1078 */ 1079 if (r->arp_ha.sa_family != ARPHRD_FDDI && 1080 r->arp_ha.sa_family != ARPHRD_ETHER && 1081 r->arp_ha.sa_family != ARPHRD_IEEE802) 1082 return -EINVAL; 1083 break; 1084 #endif 1085 default: 1086 if (r->arp_ha.sa_family != dev->type) 1087 return -EINVAL; 1088 break; 1089 } 1090 1091 neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev); 1092 err = PTR_ERR(neigh); 1093 if (!IS_ERR(neigh)) { 1094 unsigned int state = NUD_STALE; 1095 if (r->arp_flags & ATF_PERM) 1096 state = NUD_PERMANENT; 1097 err = neigh_update(neigh, (r->arp_flags & ATF_COM) ? 1098 r->arp_ha.sa_data : NULL, state, 1099 NEIGH_UPDATE_F_OVERRIDE | 1100 NEIGH_UPDATE_F_ADMIN, 0); 1101 neigh_release(neigh); 1102 } 1103 return err; 1104 } 1105 1106 static unsigned int arp_state_to_flags(struct neighbour *neigh) 1107 { 1108 if (neigh->nud_state&NUD_PERMANENT) 1109 return ATF_PERM | ATF_COM; 1110 else if (neigh->nud_state&NUD_VALID) 1111 return ATF_COM; 1112 else 1113 return 0; 1114 } 1115 1116 /* 1117 * Get an ARP cache entry. 1118 */ 1119 1120 static int arp_req_get(struct arpreq *r, struct net_device *dev) 1121 { 1122 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; 1123 struct neighbour *neigh; 1124 int err = -ENXIO; 1125 1126 neigh = neigh_lookup(&arp_tbl, &ip, dev); 1127 if (neigh) { 1128 if (!(READ_ONCE(neigh->nud_state) & NUD_NOARP)) { 1129 read_lock_bh(&neigh->lock); 1130 memcpy(r->arp_ha.sa_data, neigh->ha, 1131 min(dev->addr_len, sizeof(r->arp_ha.sa_data_min))); 1132 r->arp_flags = arp_state_to_flags(neigh); 1133 read_unlock_bh(&neigh->lock); 1134 r->arp_ha.sa_family = dev->type; 1135 strscpy(r->arp_dev, dev->name, sizeof(r->arp_dev)); 1136 err = 0; 1137 } 1138 neigh_release(neigh); 1139 } 1140 return err; 1141 } 1142 1143 int arp_invalidate(struct net_device *dev, __be32 ip, bool force) 1144 { 1145 struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev); 1146 int err = -ENXIO; 1147 struct neigh_table *tbl = &arp_tbl; 1148 1149 if (neigh) { 1150 if ((READ_ONCE(neigh->nud_state) & NUD_VALID) && !force) { 1151 neigh_release(neigh); 1152 return 0; 1153 } 1154 1155 if (READ_ONCE(neigh->nud_state) & ~NUD_NOARP) 1156 err = neigh_update(neigh, NULL, NUD_FAILED, 1157 NEIGH_UPDATE_F_OVERRIDE| 1158 NEIGH_UPDATE_F_ADMIN, 0); 1159 write_lock_bh(&tbl->lock); 1160 neigh_release(neigh); 1161 neigh_remove_one(neigh, tbl); 1162 write_unlock_bh(&tbl->lock); 1163 } 1164 1165 return err; 1166 } 1167 1168 static int arp_req_delete_public(struct net *net, struct arpreq *r, 1169 struct net_device *dev) 1170 { 1171 __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; 1172 __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; 1173 1174 if (mask == htonl(0xFFFFFFFF)) 1175 return pneigh_delete(&arp_tbl, net, &ip, dev); 1176 1177 if (mask) 1178 return -EINVAL; 1179 1180 return arp_req_set_proxy(net, dev, 0); 1181 } 1182 1183 static int arp_req_delete(struct net *net, struct arpreq *r, 1184 struct net_device *dev) 1185 { 1186 __be32 ip; 1187 1188 if (r->arp_flags & ATF_PUBL) 1189 return arp_req_delete_public(net, r, dev); 1190 1191 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; 1192 if (!dev) { 1193 struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0); 1194 if (IS_ERR(rt)) 1195 return PTR_ERR(rt); 1196 dev = rt->dst.dev; 1197 ip_rt_put(rt); 1198 if (!dev) 1199 return -EINVAL; 1200 } 1201 return arp_invalidate(dev, ip, true); 1202 } 1203 1204 /* 1205 * Handle an ARP layer I/O control request. 1206 */ 1207 1208 int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg) 1209 { 1210 int err; 1211 struct arpreq r; 1212 struct net_device *dev = NULL; 1213 1214 switch (cmd) { 1215 case SIOCDARP: 1216 case SIOCSARP: 1217 if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) 1218 return -EPERM; 1219 fallthrough; 1220 case SIOCGARP: 1221 err = copy_from_user(&r, arg, sizeof(struct arpreq)); 1222 if (err) 1223 return -EFAULT; 1224 break; 1225 default: 1226 return -EINVAL; 1227 } 1228 1229 if (r.arp_pa.sa_family != AF_INET) 1230 return -EPFNOSUPPORT; 1231 1232 if (!(r.arp_flags & ATF_PUBL) && 1233 (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB))) 1234 return -EINVAL; 1235 if (!(r.arp_flags & ATF_NETMASK)) 1236 ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr = 1237 htonl(0xFFFFFFFFUL); 1238 rtnl_lock(); 1239 if (r.arp_dev[0]) { 1240 err = -ENODEV; 1241 dev = __dev_get_by_name(net, r.arp_dev); 1242 if (!dev) 1243 goto out; 1244 1245 /* Mmmm... It is wrong... ARPHRD_NETROM==0 */ 1246 if (!r.arp_ha.sa_family) 1247 r.arp_ha.sa_family = dev->type; 1248 err = -EINVAL; 1249 if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type) 1250 goto out; 1251 } else if (cmd == SIOCGARP) { 1252 err = -ENODEV; 1253 goto out; 1254 } 1255 1256 switch (cmd) { 1257 case SIOCDARP: 1258 err = arp_req_delete(net, &r, dev); 1259 break; 1260 case SIOCSARP: 1261 err = arp_req_set(net, &r, dev); 1262 break; 1263 case SIOCGARP: 1264 err = arp_req_get(&r, dev); 1265 break; 1266 } 1267 out: 1268 rtnl_unlock(); 1269 if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r))) 1270 err = -EFAULT; 1271 return err; 1272 } 1273 1274 static int arp_netdev_event(struct notifier_block *this, unsigned long event, 1275 void *ptr) 1276 { 1277 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 1278 struct netdev_notifier_change_info *change_info; 1279 struct in_device *in_dev; 1280 bool evict_nocarrier; 1281 1282 switch (event) { 1283 case NETDEV_CHANGEADDR: 1284 neigh_changeaddr(&arp_tbl, dev); 1285 rt_cache_flush(dev_net(dev)); 1286 break; 1287 case NETDEV_CHANGE: 1288 change_info = ptr; 1289 if (change_info->flags_changed & IFF_NOARP) 1290 neigh_changeaddr(&arp_tbl, dev); 1291 1292 in_dev = __in_dev_get_rtnl(dev); 1293 if (!in_dev) 1294 evict_nocarrier = true; 1295 else 1296 evict_nocarrier = IN_DEV_ARP_EVICT_NOCARRIER(in_dev); 1297 1298 if (evict_nocarrier && !netif_carrier_ok(dev)) 1299 neigh_carrier_down(&arp_tbl, dev); 1300 break; 1301 default: 1302 break; 1303 } 1304 1305 return NOTIFY_DONE; 1306 } 1307 1308 static struct notifier_block arp_netdev_notifier = { 1309 .notifier_call = arp_netdev_event, 1310 }; 1311 1312 /* Note, that it is not on notifier chain. 1313 It is necessary, that this routine was called after route cache will be 1314 flushed. 1315 */ 1316 void arp_ifdown(struct net_device *dev) 1317 { 1318 neigh_ifdown(&arp_tbl, dev); 1319 } 1320 1321 1322 /* 1323 * Called once on startup. 1324 */ 1325 1326 static struct packet_type arp_packet_type __read_mostly = { 1327 .type = cpu_to_be16(ETH_P_ARP), 1328 .func = arp_rcv, 1329 }; 1330 1331 #ifdef CONFIG_PROC_FS 1332 #if IS_ENABLED(CONFIG_AX25) 1333 1334 /* 1335 * ax25 -> ASCII conversion 1336 */ 1337 static void ax2asc2(ax25_address *a, char *buf) 1338 { 1339 char c, *s; 1340 int n; 1341 1342 for (n = 0, s = buf; n < 6; n++) { 1343 c = (a->ax25_call[n] >> 1) & 0x7F; 1344 1345 if (c != ' ') 1346 *s++ = c; 1347 } 1348 1349 *s++ = '-'; 1350 n = (a->ax25_call[6] >> 1) & 0x0F; 1351 if (n > 9) { 1352 *s++ = '1'; 1353 n -= 10; 1354 } 1355 1356 *s++ = n + '0'; 1357 *s++ = '\0'; 1358 1359 if (*buf == '\0' || *buf == '-') { 1360 buf[0] = '*'; 1361 buf[1] = '\0'; 1362 } 1363 } 1364 #endif /* CONFIG_AX25 */ 1365 1366 #define HBUFFERLEN 30 1367 1368 static void arp_format_neigh_entry(struct seq_file *seq, 1369 struct neighbour *n) 1370 { 1371 char hbuffer[HBUFFERLEN]; 1372 int k, j; 1373 char tbuf[16]; 1374 struct net_device *dev = n->dev; 1375 int hatype = dev->type; 1376 1377 read_lock(&n->lock); 1378 /* Convert hardware address to XX:XX:XX:XX ... form. */ 1379 #if IS_ENABLED(CONFIG_AX25) 1380 if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM) 1381 ax2asc2((ax25_address *)n->ha, hbuffer); 1382 else { 1383 #endif 1384 for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) { 1385 hbuffer[k++] = hex_asc_hi(n->ha[j]); 1386 hbuffer[k++] = hex_asc_lo(n->ha[j]); 1387 hbuffer[k++] = ':'; 1388 } 1389 if (k != 0) 1390 --k; 1391 hbuffer[k] = 0; 1392 #if IS_ENABLED(CONFIG_AX25) 1393 } 1394 #endif 1395 sprintf(tbuf, "%pI4", n->primary_key); 1396 seq_printf(seq, "%-16s 0x%-10x0x%-10x%-17s * %s\n", 1397 tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name); 1398 read_unlock(&n->lock); 1399 } 1400 1401 static void arp_format_pneigh_entry(struct seq_file *seq, 1402 struct pneigh_entry *n) 1403 { 1404 struct net_device *dev = n->dev; 1405 int hatype = dev ? dev->type : 0; 1406 char tbuf[16]; 1407 1408 sprintf(tbuf, "%pI4", n->key); 1409 seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n", 1410 tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00", 1411 dev ? dev->name : "*"); 1412 } 1413 1414 static int arp_seq_show(struct seq_file *seq, void *v) 1415 { 1416 if (v == SEQ_START_TOKEN) { 1417 seq_puts(seq, "IP address HW type Flags " 1418 "HW address Mask Device\n"); 1419 } else { 1420 struct neigh_seq_state *state = seq->private; 1421 1422 if (state->flags & NEIGH_SEQ_IS_PNEIGH) 1423 arp_format_pneigh_entry(seq, v); 1424 else 1425 arp_format_neigh_entry(seq, v); 1426 } 1427 1428 return 0; 1429 } 1430 1431 static void *arp_seq_start(struct seq_file *seq, loff_t *pos) 1432 { 1433 /* Don't want to confuse "arp -a" w/ magic entries, 1434 * so we tell the generic iterator to skip NUD_NOARP. 1435 */ 1436 return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP); 1437 } 1438 1439 static const struct seq_operations arp_seq_ops = { 1440 .start = arp_seq_start, 1441 .next = neigh_seq_next, 1442 .stop = neigh_seq_stop, 1443 .show = arp_seq_show, 1444 }; 1445 #endif /* CONFIG_PROC_FS */ 1446 1447 static int __net_init arp_net_init(struct net *net) 1448 { 1449 if (!proc_create_net("arp", 0444, net->proc_net, &arp_seq_ops, 1450 sizeof(struct neigh_seq_state))) 1451 return -ENOMEM; 1452 return 0; 1453 } 1454 1455 static void __net_exit arp_net_exit(struct net *net) 1456 { 1457 remove_proc_entry("arp", net->proc_net); 1458 } 1459 1460 static struct pernet_operations arp_net_ops = { 1461 .init = arp_net_init, 1462 .exit = arp_net_exit, 1463 }; 1464 1465 void __init arp_init(void) 1466 { 1467 neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl); 1468 1469 dev_add_pack(&arp_packet_type); 1470 register_pernet_subsys(&arp_net_ops); 1471 #ifdef CONFIG_SYSCTL 1472 neigh_sysctl_register(NULL, &arp_tbl.parms, NULL); 1473 #endif 1474 register_netdevice_notifier(&arp_netdev_notifier); 1475 } 1476