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(naddr: addr, buf: haddr); |
194 | return 0; |
195 | case ARPHRD_INFINIBAND: |
196 | ip_ib_mc_map(naddr: addr, broadcast: dev->broadcast, buf: haddr); |
197 | return 0; |
198 | case ARPHRD_IPGRE: |
199 | ip_ipgre_mc_map(naddr: addr, broadcast: dev->broadcast, buf: 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(n: 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(net: dev_net(dev), dev, addr); |
243 | |
244 | parms = in_dev->arp_parms; |
245 | __neigh_parms_put(parms: 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, haddr: neigh->ha, dev, dir: 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, reason: 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: 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(v: &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(net: dev_net(dev), dev, |
353 | addr: 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(net: dev_net(dev), dev, |
361 | addr: saddr) == RTN_LOCAL) { |
362 | /* saddr should be known to target */ |
363 | if (inet_addr_onlink(in_dev, a: target, b: 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, dst: target, scope: 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: dst_ha, n: 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(n: 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, dest_ip: target, dev, src_ip: saddr, |
393 | dest_hw: dst_hw, src_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(dev: 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, dst: sip, local: tip, scope); |
430 | } |
431 | |
432 | static int arp_accept(struct in_device *in_dev, __be32 sip) |
433 | { |
434 | struct net *net = dev_net(dev: 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, dst: sip, local: 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, daddr: sip, saddr: tip, tos: 0, oif: l3mdev_master_ifindex_rcu(dev)); |
460 | if (IS_ERR(ptr: 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(dev: 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(size: arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC); |
561 | if (!skb) |
562 | return NULL; |
563 | |
564 | skb_reserve(skb, len: hlen); |
565 | skb_reset_network_header(skb); |
566 | arp = skb_put(skb, len: 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, type: ptype, daddr: dest_hw, saddr: src_hw, len: 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(pf: NFPROTO_ARP, NF_ARP_OUT, |
663 | net: dev_net(dev: skb->dev), NULL, skb, NULL, out: skb->dev, |
664 | okfn: 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(p: tha, q: sha, size: dev->addr_len); |
685 | |
686 | if (is_garp) { |
687 | *addr_type = inet_addr_type_dev_table(net, dev, addr: 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(addr: tip) || |
787 | (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(addr: 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(md: 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, addr: tip) == RTN_LOCAL && |
830 | !arp_ignore(in_dev, sip, tip)) |
831 | arp_send_dst(ARPOP_REPLY, ETH_P_ARP, dest_ip: sip, dev, src_ip: tip, |
832 | dest_hw: sha, src_hw: dev->dev_addr, target_hw: sha, dst: reply_dst); |
833 | goto out_consume_skb; |
834 | } |
835 | |
836 | if (arp->ar_op == htons(ARPOP_REQUEST) && |
837 | ip_route_input_noref(skb, dst: tip, src: sip, tos: 0, devin: 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(tbl: &arp_tbl, lladdr: sha, saddr: &sip, dev); |
850 | if (n) { |
851 | arp_send_dst(ARPOP_REPLY, ETH_P_ARP, |
852 | dest_ip: sip, dev, src_ip: tip, dest_hw: sha, |
853 | src_hw: dev->dev_addr, target_hw: sha, |
854 | dst: reply_dst); |
855 | neigh_release(neigh: 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(tbl: &arp_tbl, net, key: &tip, dev, creat: 0)))) { |
865 | n = neigh_event_ns(tbl: &arp_tbl, lladdr: sha, saddr: &sip, dev); |
866 | if (n) |
867 | neigh_release(neigh: 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 | dest_ip: sip, dev, src_ip: tip, dest_hw: sha, |
874 | src_hw: dev->dev_addr, target_hw: sha, |
875 | dst: reply_dst); |
876 | } else { |
877 | pneigh_enqueue(tbl: &arp_tbl, |
878 | p: 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(tbl: &arp_tbl, pkey: &sip, dev, creat: 0); |
889 | |
890 | addr_type = -1; |
891 | if (n || arp_accept(in_dev, sip)) { |
892 | is_garp = arp_is_garp(net, dev, addr_type: &addr_type, ar_op: 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, addr: sip) == |
908 | RTN_UNICAST))))) |
909 | n = __neigh_lookup(tbl: &arp_tbl, pkey: &sip, dev, creat: 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(neigh: n, lladdr: sha, new: state, |
933 | flags: override ? NEIGH_UPDATE_F_OVERRIDE : 0, nlmsg_pid: 0); |
934 | neigh_release(neigh: n); |
935 | } |
936 | |
937 | out_consume_skb: |
938 | consume_skb(skb); |
939 | |
940 | out_free_dst: |
941 | dst_release(dst: 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(net: dev_net(dev: skb->dev), NULL, skb); |
952 | } |
953 | |
954 | static int arp_is_multicast(const void *pkey) |
955 | { |
956 | return ipv4_is_multicast(addr: *((__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, len: 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(pf: NFPROTO_ARP, NF_ARP_IN, |
989 | net: dev_net(dev), NULL, skb, in: dev, NULL, |
990 | okfn: 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, type: r->arp_ha.sa_family, |
1032 | hwaddr: r->arp_ha.sa_data); |
1033 | if (!dev) |
1034 | return -ENODEV; |
1035 | } |
1036 | if (mask) { |
1037 | if (!pneigh_lookup(tbl: &arp_tbl, net, key: &ip, dev, creat: 1)) |
1038 | return -ENOBUFS; |
1039 | return 0; |
1040 | } |
1041 | |
1042 | return arp_req_set_proxy(net, dev, on: 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, daddr: ip, saddr: 0, RTO_ONLINK, oif: 0); |
1060 | |
1061 | if (IS_ERR(ptr: rt)) |
1062 | return PTR_ERR(ptr: 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(tbl: &arp_tbl, pkey: &ip, dev); |
1090 | err = PTR_ERR(ptr: neigh); |
1091 | if (!IS_ERR(ptr: neigh)) { |
1092 | unsigned int state = NUD_STALE; |
1093 | if (r->arp_flags & ATF_PERM) |
1094 | state = NUD_PERMANENT; |
1095 | err = neigh_update(neigh, lladdr: (r->arp_flags & ATF_COM) ? |
1096 | r->arp_ha.sa_data : NULL, new: state, |
1097 | NEIGH_UPDATE_F_OVERRIDE | |
1098 | NEIGH_UPDATE_F_ADMIN, nlmsg_pid: 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(tbl: &arp_tbl, pkey: &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(p: r->arp_dev, q: dev->name, size: 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(tbl: &arp_tbl, pkey: &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, nlmsg_pid: 0); |
1156 | write_lock_bh(&tbl->lock); |
1157 | neigh_release(neigh); |
1158 | neigh_remove_one(ndel: 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(tbl: &arp_tbl, net, key: &ip, dev); |
1173 | |
1174 | if (mask) |
1175 | return -EINVAL; |
1176 | |
1177 | return arp_req_set_proxy(net, dev, on: 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, daddr: ip, saddr: 0, RTO_ONLINK, oif: 0); |
1191 | if (IS_ERR(ptr: rt)) |
1192 | return PTR_ERR(ptr: rt); |
1193 | dev = rt->dst.dev; |
1194 | ip_rt_put(rt); |
1195 | if (!dev) |
1196 | return -EINVAL; |
1197 | } |
1198 | return arp_invalidate(dev, ip, force: 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(ns: net->user_ns, CAP_NET_ADMIN)) |
1215 | return -EPERM; |
1216 | fallthrough; |
1217 | case SIOCGARP: |
1218 | err = copy_from_user(to: &r, from: arg, n: 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, name: 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: &r, dev); |
1256 | break; |
1257 | case SIOCSARP: |
1258 | err = arp_req_set(net, r: &r, dev); |
1259 | break; |
1260 | case SIOCGARP: |
1261 | err = arp_req_get(r: &r, dev); |
1262 | break; |
1263 | } |
1264 | out: |
1265 | rtnl_unlock(); |
1266 | if (cmd == SIOCGARP && !err && copy_to_user(to: arg, from: &r, n: 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(info: 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(tbl: &arp_tbl, dev); |
1282 | rt_cache_flush(net: dev_net(dev)); |
1283 | break; |
1284 | case NETDEV_CHANGE: |
1285 | change_info = ptr; |
1286 | if (change_info->flags_changed & IFF_NOARP) |
1287 | neigh_changeaddr(tbl: &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(tbl: &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(tbl: &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(a: (ax25_address *)n->ha, buf: 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(buf: tbuf, fmt: "%pI4" , n->primary_key); |
1393 | seq_printf(m: seq, fmt: "%-16s 0x%-10x0x%-10x%-17s * %s\n" , |
1394 | tbuf, hatype, arp_state_to_flags(neigh: 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(buf: tbuf, fmt: "%pI4" , n->key); |
1406 | seq_printf(m: seq, fmt: "%-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(m: seq, s: "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, n: v); |
1421 | else |
1422 | arp_format_neigh_entry(seq, n: 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(index: NEIGH_ARP_TABLE, tbl: &arp_tbl); |
1465 | |
1466 | dev_add_pack(pt: &arp_packet_type); |
1467 | register_pernet_subsys(&arp_net_ops); |
1468 | #ifdef CONFIG_SYSCTL |
1469 | neigh_sysctl_register(NULL, p: &arp_tbl.parms, NULL); |
1470 | #endif |
1471 | register_netdevice_notifier(nb: &arp_netdev_notifier); |
1472 | } |
1473 | |