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