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, dscp: 0, oif: l3mdev_master_ifindex_rcu(dev), |
460 | scope: RT_SCOPE_UNIVERSE); |
461 | if (IS_ERR(ptr: rt)) |
462 | return 1; |
463 | if (rt->dst.dev != dev) { |
464 | __NET_INC_STATS(net, LINUX_MIB_ARPFILTER); |
465 | flag = 1; |
466 | } |
467 | ip_rt_put(rt); |
468 | return flag; |
469 | } |
470 | |
471 | /* |
472 | * Check if we can use proxy ARP for this path |
473 | */ |
474 | static inline int arp_fwd_proxy(struct in_device *in_dev, |
475 | struct net_device *dev, struct rtable *rt) |
476 | { |
477 | struct in_device *out_dev; |
478 | int imi, omi = -1; |
479 | |
480 | if (rt->dst.dev == dev) |
481 | return 0; |
482 | |
483 | if (!IN_DEV_PROXY_ARP(in_dev)) |
484 | return 0; |
485 | imi = IN_DEV_MEDIUM_ID(in_dev); |
486 | if (imi == 0) |
487 | return 1; |
488 | if (imi == -1) |
489 | return 0; |
490 | |
491 | /* place to check for proxy_arp for routes */ |
492 | |
493 | out_dev = __in_dev_get_rcu(dev: rt->dst.dev); |
494 | if (out_dev) |
495 | omi = IN_DEV_MEDIUM_ID(out_dev); |
496 | |
497 | return omi != imi && omi != -1; |
498 | } |
499 | |
500 | /* |
501 | * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev) |
502 | * |
503 | * RFC3069 supports proxy arp replies back to the same interface. This |
504 | * is done to support (ethernet) switch features, like RFC 3069, where |
505 | * the individual ports are not allowed to communicate with each |
506 | * other, BUT they are allowed to talk to the upstream router. As |
507 | * described in RFC 3069, it is possible to allow these hosts to |
508 | * communicate through the upstream router, by proxy_arp'ing. |
509 | * |
510 | * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation" |
511 | * |
512 | * This technology is known by different names: |
513 | * In RFC 3069 it is called VLAN Aggregation. |
514 | * Cisco and Allied Telesyn call it Private VLAN. |
515 | * Hewlett-Packard call it Source-Port filtering or port-isolation. |
516 | * Ericsson call it MAC-Forced Forwarding (RFC Draft). |
517 | * |
518 | */ |
519 | static inline int arp_fwd_pvlan(struct in_device *in_dev, |
520 | struct net_device *dev, struct rtable *rt, |
521 | __be32 sip, __be32 tip) |
522 | { |
523 | /* Private VLAN is only concerned about the same ethernet segment */ |
524 | if (rt->dst.dev != dev) |
525 | return 0; |
526 | |
527 | /* Don't reply on self probes (often done by windowz boxes)*/ |
528 | if (sip == tip) |
529 | return 0; |
530 | |
531 | if (IN_DEV_PROXY_ARP_PVLAN(in_dev)) |
532 | return 1; |
533 | else |
534 | return 0; |
535 | } |
536 | |
537 | /* |
538 | * Interface to link layer: send routine and receive handler. |
539 | */ |
540 | |
541 | /* |
542 | * Create an arp packet. If dest_hw is not set, we create a broadcast |
543 | * message. |
544 | */ |
545 | struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip, |
546 | struct net_device *dev, __be32 src_ip, |
547 | const unsigned char *dest_hw, |
548 | const unsigned char *src_hw, |
549 | const unsigned char *target_hw) |
550 | { |
551 | struct sk_buff *skb; |
552 | struct arphdr *arp; |
553 | unsigned char *arp_ptr; |
554 | int hlen = LL_RESERVED_SPACE(dev); |
555 | int tlen = dev->needed_tailroom; |
556 | |
557 | /* |
558 | * Allocate a buffer |
559 | */ |
560 | |
561 | skb = alloc_skb(size: arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC); |
562 | if (!skb) |
563 | return NULL; |
564 | |
565 | skb_reserve(skb, len: hlen); |
566 | skb_reset_network_header(skb); |
567 | arp = skb_put(skb, len: arp_hdr_len(dev)); |
568 | skb->dev = dev; |
569 | skb->protocol = htons(ETH_P_ARP); |
570 | if (!src_hw) |
571 | src_hw = dev->dev_addr; |
572 | if (!dest_hw) |
573 | dest_hw = dev->broadcast; |
574 | |
575 | /* |
576 | * Fill the device header for the ARP frame |
577 | */ |
578 | if (dev_hard_header(skb, dev, type: ptype, daddr: dest_hw, saddr: src_hw, len: skb->len) < 0) |
579 | goto out; |
580 | |
581 | /* |
582 | * Fill out the arp protocol part. |
583 | * |
584 | * The arp hardware type should match the device type, except for FDDI, |
585 | * which (according to RFC 1390) should always equal 1 (Ethernet). |
586 | */ |
587 | /* |
588 | * Exceptions everywhere. AX.25 uses the AX.25 PID value not the |
589 | * DIX code for the protocol. Make these device structure fields. |
590 | */ |
591 | switch (dev->type) { |
592 | default: |
593 | arp->ar_hrd = htons(dev->type); |
594 | arp->ar_pro = htons(ETH_P_IP); |
595 | break; |
596 | |
597 | #if IS_ENABLED(CONFIG_AX25) |
598 | case ARPHRD_AX25: |
599 | arp->ar_hrd = htons(ARPHRD_AX25); |
600 | arp->ar_pro = htons(AX25_P_IP); |
601 | break; |
602 | |
603 | #if IS_ENABLED(CONFIG_NETROM) |
604 | case ARPHRD_NETROM: |
605 | arp->ar_hrd = htons(ARPHRD_NETROM); |
606 | arp->ar_pro = htons(AX25_P_IP); |
607 | break; |
608 | #endif |
609 | #endif |
610 | |
611 | #if IS_ENABLED(CONFIG_FDDI) |
612 | case ARPHRD_FDDI: |
613 | arp->ar_hrd = htons(ARPHRD_ETHER); |
614 | arp->ar_pro = htons(ETH_P_IP); |
615 | break; |
616 | #endif |
617 | } |
618 | |
619 | arp->ar_hln = dev->addr_len; |
620 | arp->ar_pln = 4; |
621 | arp->ar_op = htons(type); |
622 | |
623 | arp_ptr = (unsigned char *)(arp + 1); |
624 | |
625 | memcpy(arp_ptr, src_hw, dev->addr_len); |
626 | arp_ptr += dev->addr_len; |
627 | memcpy(arp_ptr, &src_ip, 4); |
628 | arp_ptr += 4; |
629 | |
630 | switch (dev->type) { |
631 | #if IS_ENABLED(CONFIG_FIREWIRE_NET) |
632 | case ARPHRD_IEEE1394: |
633 | break; |
634 | #endif |
635 | default: |
636 | if (target_hw) |
637 | memcpy(arp_ptr, target_hw, dev->addr_len); |
638 | else |
639 | memset(arp_ptr, 0, dev->addr_len); |
640 | arp_ptr += dev->addr_len; |
641 | } |
642 | memcpy(arp_ptr, &dest_ip, 4); |
643 | |
644 | return skb; |
645 | |
646 | out: |
647 | kfree_skb(skb); |
648 | return NULL; |
649 | } |
650 | EXPORT_SYMBOL(arp_create); |
651 | |
652 | static int arp_xmit_finish(struct net *net, struct sock *sk, struct sk_buff *skb) |
653 | { |
654 | return dev_queue_xmit(skb); |
655 | } |
656 | |
657 | /* |
658 | * Send an arp packet. |
659 | */ |
660 | void arp_xmit(struct sk_buff *skb) |
661 | { |
662 | rcu_read_lock(); |
663 | /* Send it off, maybe filter it using firewalling first. */ |
664 | NF_HOOK(pf: NFPROTO_ARP, NF_ARP_OUT, |
665 | net: dev_net_rcu(dev: skb->dev), NULL, skb, NULL, out: skb->dev, |
666 | okfn: arp_xmit_finish); |
667 | rcu_read_unlock(); |
668 | } |
669 | EXPORT_SYMBOL(arp_xmit); |
670 | |
671 | static bool arp_is_garp(struct net *net, struct net_device *dev, |
672 | int *addr_type, __be16 ar_op, |
673 | __be32 sip, __be32 tip, |
674 | unsigned char *sha, unsigned char *tha) |
675 | { |
676 | bool is_garp = tip == sip; |
677 | |
678 | /* Gratuitous ARP _replies_ also require target hwaddr to be |
679 | * the same as source. |
680 | */ |
681 | if (is_garp && ar_op == htons(ARPOP_REPLY)) |
682 | is_garp = |
683 | /* IPv4 over IEEE 1394 doesn't provide target |
684 | * hardware address field in its ARP payload. |
685 | */ |
686 | tha && |
687 | !memcmp(p: tha, q: sha, size: dev->addr_len); |
688 | |
689 | if (is_garp) { |
690 | *addr_type = inet_addr_type_dev_table(net, dev, addr: sip); |
691 | if (*addr_type != RTN_UNICAST) |
692 | is_garp = false; |
693 | } |
694 | return is_garp; |
695 | } |
696 | |
697 | /* |
698 | * Process an arp request. |
699 | */ |
700 | |
701 | static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb) |
702 | { |
703 | struct net_device *dev = skb->dev; |
704 | struct in_device *in_dev = __in_dev_get_rcu(dev); |
705 | struct arphdr *arp; |
706 | unsigned char *arp_ptr; |
707 | struct rtable *rt; |
708 | unsigned char *sha; |
709 | unsigned char *tha = NULL; |
710 | __be32 sip, tip; |
711 | u16 dev_type = dev->type; |
712 | int addr_type; |
713 | struct neighbour *n; |
714 | struct dst_entry *reply_dst = NULL; |
715 | bool is_garp = false; |
716 | |
717 | /* arp_rcv below verifies the ARP header and verifies the device |
718 | * is ARP'able. |
719 | */ |
720 | |
721 | if (!in_dev) |
722 | goto out_free_skb; |
723 | |
724 | arp = arp_hdr(skb); |
725 | |
726 | switch (dev_type) { |
727 | default: |
728 | if (arp->ar_pro != htons(ETH_P_IP) || |
729 | htons(dev_type) != arp->ar_hrd) |
730 | goto out_free_skb; |
731 | break; |
732 | case ARPHRD_ETHER: |
733 | case ARPHRD_FDDI: |
734 | case ARPHRD_IEEE802: |
735 | /* |
736 | * ETHERNET, and Fibre Channel (which are IEEE 802 |
737 | * devices, according to RFC 2625) devices will accept ARP |
738 | * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2). |
739 | * This is the case also of FDDI, where the RFC 1390 says that |
740 | * FDDI devices should accept ARP hardware of (1) Ethernet, |
741 | * however, to be more robust, we'll accept both 1 (Ethernet) |
742 | * or 6 (IEEE 802.2) |
743 | */ |
744 | if ((arp->ar_hrd != htons(ARPHRD_ETHER) && |
745 | arp->ar_hrd != htons(ARPHRD_IEEE802)) || |
746 | arp->ar_pro != htons(ETH_P_IP)) |
747 | goto out_free_skb; |
748 | break; |
749 | case ARPHRD_AX25: |
750 | if (arp->ar_pro != htons(AX25_P_IP) || |
751 | arp->ar_hrd != htons(ARPHRD_AX25)) |
752 | goto out_free_skb; |
753 | break; |
754 | case ARPHRD_NETROM: |
755 | if (arp->ar_pro != htons(AX25_P_IP) || |
756 | arp->ar_hrd != htons(ARPHRD_NETROM)) |
757 | goto out_free_skb; |
758 | break; |
759 | } |
760 | |
761 | /* Understand only these message types */ |
762 | |
763 | if (arp->ar_op != htons(ARPOP_REPLY) && |
764 | arp->ar_op != htons(ARPOP_REQUEST)) |
765 | goto out_free_skb; |
766 | |
767 | /* |
768 | * Extract fields |
769 | */ |
770 | arp_ptr = (unsigned char *)(arp + 1); |
771 | sha = arp_ptr; |
772 | arp_ptr += dev->addr_len; |
773 | memcpy(&sip, arp_ptr, 4); |
774 | arp_ptr += 4; |
775 | switch (dev_type) { |
776 | #if IS_ENABLED(CONFIG_FIREWIRE_NET) |
777 | case ARPHRD_IEEE1394: |
778 | break; |
779 | #endif |
780 | default: |
781 | tha = arp_ptr; |
782 | arp_ptr += dev->addr_len; |
783 | } |
784 | memcpy(&tip, arp_ptr, 4); |
785 | /* |
786 | * Check for bad requests for 127.x.x.x and requests for multicast |
787 | * addresses. If this is one such, delete it. |
788 | */ |
789 | if (ipv4_is_multicast(addr: tip) || |
790 | (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(addr: tip))) |
791 | goto out_free_skb; |
792 | |
793 | /* |
794 | * For some 802.11 wireless deployments (and possibly other networks), |
795 | * there will be an ARP proxy and gratuitous ARP frames are attacks |
796 | * and thus should not be accepted. |
797 | */ |
798 | if (sip == tip && IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP)) |
799 | goto out_free_skb; |
800 | |
801 | /* |
802 | * Special case: We must set Frame Relay source Q.922 address |
803 | */ |
804 | if (dev_type == ARPHRD_DLCI) |
805 | sha = dev->broadcast; |
806 | |
807 | /* |
808 | * Process entry. The idea here is we want to send a reply if it is a |
809 | * request for us or if it is a request for someone else that we hold |
810 | * a proxy for. We want to add an entry to our cache if it is a reply |
811 | * to us or if it is a request for our address. |
812 | * (The assumption for this last is that if someone is requesting our |
813 | * address, they are probably intending to talk to us, so it saves time |
814 | * if we cache their address. Their address is also probably not in |
815 | * our cache, since ours is not in their cache.) |
816 | * |
817 | * Putting this another way, we only care about replies if they are to |
818 | * us, in which case we add them to the cache. For requests, we care |
819 | * about those for us and those for our proxies. We reply to both, |
820 | * and in the case of requests for us we add the requester to the arp |
821 | * cache. |
822 | */ |
823 | |
824 | if (arp->ar_op == htons(ARPOP_REQUEST) && skb_metadata_dst(skb)) |
825 | reply_dst = (struct dst_entry *) |
826 | iptunnel_metadata_reply(md: skb_metadata_dst(skb), |
827 | GFP_ATOMIC); |
828 | |
829 | /* Special case: IPv4 duplicate address detection packet (RFC2131) */ |
830 | if (sip == 0) { |
831 | if (arp->ar_op == htons(ARPOP_REQUEST) && |
832 | inet_addr_type_dev_table(net, dev, addr: tip) == RTN_LOCAL && |
833 | !arp_ignore(in_dev, sip, tip)) |
834 | arp_send_dst(ARPOP_REPLY, ETH_P_ARP, dest_ip: sip, dev, src_ip: tip, |
835 | dest_hw: sha, src_hw: dev->dev_addr, target_hw: sha, dst: reply_dst); |
836 | goto out_consume_skb; |
837 | } |
838 | |
839 | if (arp->ar_op == htons(ARPOP_REQUEST) && |
840 | ip_route_input_noref(skb, daddr: tip, saddr: sip, dscp: 0, dev) == 0) { |
841 | |
842 | rt = skb_rtable(skb); |
843 | addr_type = rt->rt_type; |
844 | |
845 | if (addr_type == RTN_LOCAL) { |
846 | int dont_send; |
847 | |
848 | dont_send = arp_ignore(in_dev, sip, tip); |
849 | if (!dont_send && IN_DEV_ARPFILTER(in_dev)) |
850 | dont_send = arp_filter(sip, tip, dev); |
851 | if (!dont_send) { |
852 | n = neigh_event_ns(tbl: &arp_tbl, lladdr: sha, saddr: &sip, dev); |
853 | if (n) { |
854 | arp_send_dst(ARPOP_REPLY, ETH_P_ARP, |
855 | dest_ip: sip, dev, src_ip: tip, dest_hw: sha, |
856 | src_hw: dev->dev_addr, target_hw: sha, |
857 | dst: reply_dst); |
858 | neigh_release(neigh: n); |
859 | } |
860 | } |
861 | goto out_consume_skb; |
862 | } else if (IN_DEV_FORWARD(in_dev)) { |
863 | if (addr_type == RTN_UNICAST && |
864 | (arp_fwd_proxy(in_dev, dev, rt) || |
865 | arp_fwd_pvlan(in_dev, dev, rt, sip, tip) || |
866 | (rt->dst.dev != dev && |
867 | pneigh_lookup(tbl: &arp_tbl, net, key: &tip, dev, creat: 0)))) { |
868 | n = neigh_event_ns(tbl: &arp_tbl, lladdr: sha, saddr: &sip, dev); |
869 | if (n) |
870 | neigh_release(neigh: n); |
871 | |
872 | if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED || |
873 | skb->pkt_type == PACKET_HOST || |
874 | NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) { |
875 | arp_send_dst(ARPOP_REPLY, ETH_P_ARP, |
876 | dest_ip: sip, dev, src_ip: tip, dest_hw: sha, |
877 | src_hw: dev->dev_addr, target_hw: sha, |
878 | dst: reply_dst); |
879 | } else { |
880 | pneigh_enqueue(tbl: &arp_tbl, |
881 | p: in_dev->arp_parms, skb); |
882 | goto out_free_dst; |
883 | } |
884 | goto out_consume_skb; |
885 | } |
886 | } |
887 | } |
888 | |
889 | /* Update our ARP tables */ |
890 | |
891 | n = __neigh_lookup(tbl: &arp_tbl, pkey: &sip, dev, creat: 0); |
892 | |
893 | addr_type = -1; |
894 | if (n || arp_accept(in_dev, sip)) { |
895 | is_garp = arp_is_garp(net, dev, addr_type: &addr_type, ar_op: arp->ar_op, |
896 | sip, tip, sha, tha); |
897 | } |
898 | |
899 | if (arp_accept(in_dev, sip)) { |
900 | /* Unsolicited ARP is not accepted by default. |
901 | It is possible, that this option should be enabled for some |
902 | devices (strip is candidate) |
903 | */ |
904 | if (!n && |
905 | (is_garp || |
906 | (arp->ar_op == htons(ARPOP_REPLY) && |
907 | (addr_type == RTN_UNICAST || |
908 | (addr_type < 0 && |
909 | /* postpone calculation to as late as possible */ |
910 | inet_addr_type_dev_table(net, dev, addr: sip) == |
911 | RTN_UNICAST))))) |
912 | n = __neigh_lookup(tbl: &arp_tbl, pkey: &sip, dev, creat: 1); |
913 | } |
914 | |
915 | if (n) { |
916 | int state = NUD_REACHABLE; |
917 | int override; |
918 | |
919 | /* If several different ARP replies follows back-to-back, |
920 | use the FIRST one. It is possible, if several proxy |
921 | agents are active. Taking the first reply prevents |
922 | arp trashing and chooses the fastest router. |
923 | */ |
924 | override = time_after(jiffies, |
925 | n->updated + |
926 | NEIGH_VAR(n->parms, LOCKTIME)) || |
927 | is_garp; |
928 | |
929 | /* Broadcast replies and request packets |
930 | do not assert neighbour reachability. |
931 | */ |
932 | if (arp->ar_op != htons(ARPOP_REPLY) || |
933 | skb->pkt_type != PACKET_HOST) |
934 | state = NUD_STALE; |
935 | neigh_update(neigh: n, lladdr: sha, new: state, |
936 | flags: override ? NEIGH_UPDATE_F_OVERRIDE : 0, nlmsg_pid: 0); |
937 | neigh_release(neigh: n); |
938 | } |
939 | |
940 | out_consume_skb: |
941 | consume_skb(skb); |
942 | |
943 | out_free_dst: |
944 | dst_release(dst: reply_dst); |
945 | return NET_RX_SUCCESS; |
946 | |
947 | out_free_skb: |
948 | kfree_skb(skb); |
949 | return NET_RX_DROP; |
950 | } |
951 | |
952 | static void parp_redo(struct sk_buff *skb) |
953 | { |
954 | arp_process(net: dev_net(dev: skb->dev), NULL, skb); |
955 | } |
956 | |
957 | static int arp_is_multicast(const void *pkey) |
958 | { |
959 | return ipv4_is_multicast(addr: *((__be32 *)pkey)); |
960 | } |
961 | |
962 | /* |
963 | * Receive an arp request from the device layer. |
964 | */ |
965 | |
966 | static int arp_rcv(struct sk_buff *skb, struct net_device *dev, |
967 | struct packet_type *pt, struct net_device *orig_dev) |
968 | { |
969 | const struct arphdr *arp; |
970 | |
971 | /* do not tweak dropwatch on an ARP we will ignore */ |
972 | if (dev->flags & IFF_NOARP || |
973 | skb->pkt_type == PACKET_OTHERHOST || |
974 | skb->pkt_type == PACKET_LOOPBACK) |
975 | goto consumeskb; |
976 | |
977 | skb = skb_share_check(skb, GFP_ATOMIC); |
978 | if (!skb) |
979 | goto out_of_mem; |
980 | |
981 | /* ARP header, plus 2 device addresses, plus 2 IP addresses. */ |
982 | if (!pskb_may_pull(skb, len: arp_hdr_len(dev))) |
983 | goto freeskb; |
984 | |
985 | arp = arp_hdr(skb); |
986 | if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4) |
987 | goto freeskb; |
988 | |
989 | memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb)); |
990 | |
991 | return NF_HOOK(pf: NFPROTO_ARP, NF_ARP_IN, |
992 | net: dev_net(dev), NULL, skb, in: dev, NULL, |
993 | okfn: arp_process); |
994 | |
995 | consumeskb: |
996 | consume_skb(skb); |
997 | return NET_RX_SUCCESS; |
998 | freeskb: |
999 | kfree_skb(skb); |
1000 | out_of_mem: |
1001 | return NET_RX_DROP; |
1002 | } |
1003 | |
1004 | /* |
1005 | * User level interface (ioctl) |
1006 | */ |
1007 | |
1008 | static struct net_device *arp_req_dev_by_name(struct net *net, struct arpreq *r, |
1009 | bool getarp) |
1010 | { |
1011 | struct net_device *dev; |
1012 | |
1013 | if (getarp) |
1014 | dev = dev_get_by_name_rcu(net, name: r->arp_dev); |
1015 | else |
1016 | dev = __dev_get_by_name(net, name: r->arp_dev); |
1017 | if (!dev) |
1018 | return ERR_PTR(error: -ENODEV); |
1019 | |
1020 | /* Mmmm... It is wrong... ARPHRD_NETROM == 0 */ |
1021 | if (!r->arp_ha.sa_family) |
1022 | r->arp_ha.sa_family = dev->type; |
1023 | |
1024 | if ((r->arp_flags & ATF_COM) && r->arp_ha.sa_family != dev->type) |
1025 | return ERR_PTR(error: -EINVAL); |
1026 | |
1027 | return dev; |
1028 | } |
1029 | |
1030 | static struct net_device *arp_req_dev(struct net *net, struct arpreq *r) |
1031 | { |
1032 | struct net_device *dev; |
1033 | struct rtable *rt; |
1034 | __be32 ip; |
1035 | |
1036 | if (r->arp_dev[0]) |
1037 | return arp_req_dev_by_name(net, r, getarp: false); |
1038 | |
1039 | if (r->arp_flags & ATF_PUBL) |
1040 | return NULL; |
1041 | |
1042 | ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; |
1043 | |
1044 | rt = ip_route_output(net, daddr: ip, saddr: 0, dscp: 0, oif: 0, scope: RT_SCOPE_LINK); |
1045 | if (IS_ERR(ptr: rt)) |
1046 | return ERR_CAST(ptr: rt); |
1047 | |
1048 | dev = rt->dst.dev; |
1049 | ip_rt_put(rt); |
1050 | |
1051 | if (!dev) |
1052 | return ERR_PTR(error: -EINVAL); |
1053 | |
1054 | return dev; |
1055 | } |
1056 | |
1057 | /* |
1058 | * Set (create) an ARP cache entry. |
1059 | */ |
1060 | |
1061 | static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on) |
1062 | { |
1063 | if (!dev) { |
1064 | IPV4_DEVCONF_ALL(net, PROXY_ARP) = on; |
1065 | return 0; |
1066 | } |
1067 | if (__in_dev_get_rtnl_net(dev)) { |
1068 | IN_DEV_CONF_SET(__in_dev_get_rtnl_net(dev), PROXY_ARP, on); |
1069 | return 0; |
1070 | } |
1071 | return -ENXIO; |
1072 | } |
1073 | |
1074 | static int arp_req_set_public(struct net *net, struct arpreq *r, |
1075 | struct net_device *dev) |
1076 | { |
1077 | __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; |
1078 | |
1079 | if (!dev && (r->arp_flags & ATF_COM)) { |
1080 | dev = dev_getbyhwaddr(net, type: r->arp_ha.sa_family, |
1081 | hwaddr: r->arp_ha.sa_data); |
1082 | if (!dev) |
1083 | return -ENODEV; |
1084 | } |
1085 | if (mask) { |
1086 | __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; |
1087 | |
1088 | if (!pneigh_lookup(tbl: &arp_tbl, net, key: &ip, dev, creat: 1)) |
1089 | return -ENOBUFS; |
1090 | return 0; |
1091 | } |
1092 | |
1093 | return arp_req_set_proxy(net, dev, on: 1); |
1094 | } |
1095 | |
1096 | static int arp_req_set(struct net *net, struct arpreq *r) |
1097 | { |
1098 | struct neighbour *neigh; |
1099 | struct net_device *dev; |
1100 | __be32 ip; |
1101 | int err; |
1102 | |
1103 | dev = arp_req_dev(net, r); |
1104 | if (IS_ERR(ptr: dev)) |
1105 | return PTR_ERR(ptr: dev); |
1106 | |
1107 | if (r->arp_flags & ATF_PUBL) |
1108 | return arp_req_set_public(net, r, dev); |
1109 | |
1110 | switch (dev->type) { |
1111 | #if IS_ENABLED(CONFIG_FDDI) |
1112 | case ARPHRD_FDDI: |
1113 | /* |
1114 | * According to RFC 1390, FDDI devices should accept ARP |
1115 | * hardware types of 1 (Ethernet). However, to be more |
1116 | * robust, we'll accept hardware types of either 1 (Ethernet) |
1117 | * or 6 (IEEE 802.2). |
1118 | */ |
1119 | if (r->arp_ha.sa_family != ARPHRD_FDDI && |
1120 | r->arp_ha.sa_family != ARPHRD_ETHER && |
1121 | r->arp_ha.sa_family != ARPHRD_IEEE802) |
1122 | return -EINVAL; |
1123 | break; |
1124 | #endif |
1125 | default: |
1126 | if (r->arp_ha.sa_family != dev->type) |
1127 | return -EINVAL; |
1128 | break; |
1129 | } |
1130 | |
1131 | ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; |
1132 | |
1133 | neigh = __neigh_lookup_errno(tbl: &arp_tbl, pkey: &ip, dev); |
1134 | err = PTR_ERR(ptr: neigh); |
1135 | if (!IS_ERR(ptr: neigh)) { |
1136 | unsigned int state = NUD_STALE; |
1137 | |
1138 | if (r->arp_flags & ATF_PERM) { |
1139 | r->arp_flags |= ATF_COM; |
1140 | state = NUD_PERMANENT; |
1141 | } |
1142 | |
1143 | err = neigh_update(neigh, lladdr: (r->arp_flags & ATF_COM) ? |
1144 | r->arp_ha.sa_data : NULL, new: state, |
1145 | NEIGH_UPDATE_F_OVERRIDE | |
1146 | NEIGH_UPDATE_F_ADMIN, nlmsg_pid: 0); |
1147 | neigh_release(neigh); |
1148 | } |
1149 | return err; |
1150 | } |
1151 | |
1152 | static unsigned int arp_state_to_flags(struct neighbour *neigh) |
1153 | { |
1154 | if (neigh->nud_state&NUD_PERMANENT) |
1155 | return ATF_PERM | ATF_COM; |
1156 | else if (neigh->nud_state&NUD_VALID) |
1157 | return ATF_COM; |
1158 | else |
1159 | return 0; |
1160 | } |
1161 | |
1162 | /* |
1163 | * Get an ARP cache entry. |
1164 | */ |
1165 | |
1166 | static int arp_req_get(struct net *net, struct arpreq *r) |
1167 | { |
1168 | __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; |
1169 | struct neighbour *neigh; |
1170 | struct net_device *dev; |
1171 | |
1172 | if (!r->arp_dev[0]) |
1173 | return -ENODEV; |
1174 | |
1175 | dev = arp_req_dev_by_name(net, r, getarp: true); |
1176 | if (IS_ERR(ptr: dev)) |
1177 | return PTR_ERR(ptr: dev); |
1178 | |
1179 | neigh = neigh_lookup(tbl: &arp_tbl, pkey: &ip, dev); |
1180 | if (!neigh) |
1181 | return -ENXIO; |
1182 | |
1183 | if (READ_ONCE(neigh->nud_state) & NUD_NOARP) { |
1184 | neigh_release(neigh); |
1185 | return -ENXIO; |
1186 | } |
1187 | |
1188 | read_lock_bh(&neigh->lock); |
1189 | memcpy(r->arp_ha.sa_data, neigh->ha, |
1190 | min(dev->addr_len, sizeof(r->arp_ha.sa_data_min))); |
1191 | r->arp_flags = arp_state_to_flags(neigh); |
1192 | read_unlock_bh(&neigh->lock); |
1193 | |
1194 | neigh_release(neigh); |
1195 | |
1196 | r->arp_ha.sa_family = dev->type; |
1197 | netdev_copy_name(dev, name: r->arp_dev); |
1198 | |
1199 | return 0; |
1200 | } |
1201 | |
1202 | int arp_invalidate(struct net_device *dev, __be32 ip, bool force) |
1203 | { |
1204 | struct neighbour *neigh = neigh_lookup(tbl: &arp_tbl, pkey: &ip, dev); |
1205 | int err = -ENXIO; |
1206 | struct neigh_table *tbl = &arp_tbl; |
1207 | |
1208 | if (neigh) { |
1209 | if ((READ_ONCE(neigh->nud_state) & NUD_VALID) && !force) { |
1210 | neigh_release(neigh); |
1211 | return 0; |
1212 | } |
1213 | |
1214 | if (READ_ONCE(neigh->nud_state) & ~NUD_NOARP) |
1215 | err = neigh_update(neigh, NULL, NUD_FAILED, |
1216 | NEIGH_UPDATE_F_OVERRIDE| |
1217 | NEIGH_UPDATE_F_ADMIN, nlmsg_pid: 0); |
1218 | write_lock_bh(&tbl->lock); |
1219 | neigh_release(neigh); |
1220 | neigh_remove_one(ndel: neigh); |
1221 | write_unlock_bh(&tbl->lock); |
1222 | } |
1223 | |
1224 | return err; |
1225 | } |
1226 | |
1227 | static int arp_req_delete_public(struct net *net, struct arpreq *r, |
1228 | struct net_device *dev) |
1229 | { |
1230 | __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; |
1231 | |
1232 | if (mask) { |
1233 | __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; |
1234 | |
1235 | return pneigh_delete(tbl: &arp_tbl, net, key: &ip, dev); |
1236 | } |
1237 | |
1238 | return arp_req_set_proxy(net, dev, on: 0); |
1239 | } |
1240 | |
1241 | static int arp_req_delete(struct net *net, struct arpreq *r) |
1242 | { |
1243 | struct net_device *dev; |
1244 | __be32 ip; |
1245 | |
1246 | dev = arp_req_dev(net, r); |
1247 | if (IS_ERR(ptr: dev)) |
1248 | return PTR_ERR(ptr: dev); |
1249 | |
1250 | if (r->arp_flags & ATF_PUBL) |
1251 | return arp_req_delete_public(net, r, dev); |
1252 | |
1253 | ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; |
1254 | |
1255 | return arp_invalidate(dev, ip, force: true); |
1256 | } |
1257 | |
1258 | /* |
1259 | * Handle an ARP layer I/O control request. |
1260 | */ |
1261 | |
1262 | int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg) |
1263 | { |
1264 | struct arpreq r; |
1265 | __be32 *netmask; |
1266 | int err; |
1267 | |
1268 | switch (cmd) { |
1269 | case SIOCDARP: |
1270 | case SIOCSARP: |
1271 | if (!ns_capable(ns: net->user_ns, CAP_NET_ADMIN)) |
1272 | return -EPERM; |
1273 | fallthrough; |
1274 | case SIOCGARP: |
1275 | err = copy_from_user(to: &r, from: arg, n: sizeof(struct arpreq)); |
1276 | if (err) |
1277 | return -EFAULT; |
1278 | break; |
1279 | default: |
1280 | return -EINVAL; |
1281 | } |
1282 | |
1283 | if (r.arp_pa.sa_family != AF_INET) |
1284 | return -EPFNOSUPPORT; |
1285 | |
1286 | if (!(r.arp_flags & ATF_PUBL) && |
1287 | (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB))) |
1288 | return -EINVAL; |
1289 | |
1290 | netmask = &((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr; |
1291 | if (!(r.arp_flags & ATF_NETMASK)) |
1292 | *netmask = htonl(0xFFFFFFFFUL); |
1293 | else if (*netmask && *netmask != htonl(0xFFFFFFFFUL)) |
1294 | return -EINVAL; |
1295 | |
1296 | switch (cmd) { |
1297 | case SIOCDARP: |
1298 | rtnl_net_lock(net); |
1299 | err = arp_req_delete(net, r: &r); |
1300 | rtnl_net_unlock(net); |
1301 | break; |
1302 | case SIOCSARP: |
1303 | rtnl_net_lock(net); |
1304 | err = arp_req_set(net, r: &r); |
1305 | rtnl_net_unlock(net); |
1306 | break; |
1307 | case SIOCGARP: |
1308 | rcu_read_lock(); |
1309 | err = arp_req_get(net, r: &r); |
1310 | rcu_read_unlock(); |
1311 | |
1312 | if (!err && copy_to_user(to: arg, from: &r, n: sizeof(r))) |
1313 | err = -EFAULT; |
1314 | break; |
1315 | } |
1316 | |
1317 | return err; |
1318 | } |
1319 | |
1320 | static int arp_netdev_event(struct notifier_block *this, unsigned long event, |
1321 | void *ptr) |
1322 | { |
1323 | struct net_device *dev = netdev_notifier_info_to_dev(info: ptr); |
1324 | struct netdev_notifier_change_info *change_info; |
1325 | struct in_device *in_dev; |
1326 | bool evict_nocarrier; |
1327 | |
1328 | switch (event) { |
1329 | case NETDEV_CHANGEADDR: |
1330 | neigh_changeaddr(tbl: &arp_tbl, dev); |
1331 | rt_cache_flush(net: dev_net(dev)); |
1332 | break; |
1333 | case NETDEV_CHANGE: |
1334 | change_info = ptr; |
1335 | if (change_info->flags_changed & IFF_NOARP) |
1336 | neigh_changeaddr(tbl: &arp_tbl, dev); |
1337 | |
1338 | in_dev = __in_dev_get_rtnl(dev); |
1339 | if (!in_dev) |
1340 | evict_nocarrier = true; |
1341 | else |
1342 | evict_nocarrier = IN_DEV_ARP_EVICT_NOCARRIER(in_dev); |
1343 | |
1344 | if (evict_nocarrier && !netif_carrier_ok(dev)) |
1345 | neigh_carrier_down(tbl: &arp_tbl, dev); |
1346 | break; |
1347 | default: |
1348 | break; |
1349 | } |
1350 | |
1351 | return NOTIFY_DONE; |
1352 | } |
1353 | |
1354 | static struct notifier_block arp_netdev_notifier = { |
1355 | .notifier_call = arp_netdev_event, |
1356 | }; |
1357 | |
1358 | /* Note, that it is not on notifier chain. |
1359 | It is necessary, that this routine was called after route cache will be |
1360 | flushed. |
1361 | */ |
1362 | void arp_ifdown(struct net_device *dev) |
1363 | { |
1364 | neigh_ifdown(tbl: &arp_tbl, dev); |
1365 | } |
1366 | |
1367 | |
1368 | /* |
1369 | * Called once on startup. |
1370 | */ |
1371 | |
1372 | static struct packet_type arp_packet_type __read_mostly = { |
1373 | .type = cpu_to_be16(ETH_P_ARP), |
1374 | .func = arp_rcv, |
1375 | }; |
1376 | |
1377 | #ifdef CONFIG_PROC_FS |
1378 | #if IS_ENABLED(CONFIG_AX25) |
1379 | |
1380 | /* |
1381 | * ax25 -> ASCII conversion |
1382 | */ |
1383 | static void ax2asc2(ax25_address *a, char *buf) |
1384 | { |
1385 | char c, *s; |
1386 | int n; |
1387 | |
1388 | for (n = 0, s = buf; n < 6; n++) { |
1389 | c = (a->ax25_call[n] >> 1) & 0x7F; |
1390 | |
1391 | if (c != ' ') |
1392 | *s++ = c; |
1393 | } |
1394 | |
1395 | *s++ = '-'; |
1396 | n = (a->ax25_call[6] >> 1) & 0x0F; |
1397 | if (n > 9) { |
1398 | *s++ = '1'; |
1399 | n -= 10; |
1400 | } |
1401 | |
1402 | *s++ = n + '0'; |
1403 | *s++ = '\0'; |
1404 | |
1405 | if (*buf == '\0' || *buf == '-') { |
1406 | buf[0] = '*'; |
1407 | buf[1] = '\0'; |
1408 | } |
1409 | } |
1410 | #endif /* CONFIG_AX25 */ |
1411 | |
1412 | #define HBUFFERLEN 30 |
1413 | |
1414 | static void arp_format_neigh_entry(struct seq_file *seq, |
1415 | struct neighbour *n) |
1416 | { |
1417 | char hbuffer[HBUFFERLEN]; |
1418 | int k, j; |
1419 | char tbuf[16]; |
1420 | struct net_device *dev = n->dev; |
1421 | int hatype = dev->type; |
1422 | |
1423 | read_lock(&n->lock); |
1424 | /* Convert hardware address to XX:XX:XX:XX ... form. */ |
1425 | #if IS_ENABLED(CONFIG_AX25) |
1426 | if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM) |
1427 | ax2asc2(a: (ax25_address *)n->ha, buf: hbuffer); |
1428 | else { |
1429 | #endif |
1430 | for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) { |
1431 | hbuffer[k++] = hex_asc_hi(n->ha[j]); |
1432 | hbuffer[k++] = hex_asc_lo(n->ha[j]); |
1433 | hbuffer[k++] = ':'; |
1434 | } |
1435 | if (k != 0) |
1436 | --k; |
1437 | hbuffer[k] = 0; |
1438 | #if IS_ENABLED(CONFIG_AX25) |
1439 | } |
1440 | #endif |
1441 | sprintf(buf: tbuf, fmt: "%pI4", n->primary_key); |
1442 | seq_printf(m: seq, fmt: "%-16s 0x%-10x0x%-10x%-17s * %s\n", |
1443 | tbuf, hatype, arp_state_to_flags(neigh: n), hbuffer, dev->name); |
1444 | read_unlock(&n->lock); |
1445 | } |
1446 | |
1447 | static void arp_format_pneigh_entry(struct seq_file *seq, |
1448 | struct pneigh_entry *n) |
1449 | { |
1450 | struct net_device *dev = n->dev; |
1451 | int hatype = dev ? dev->type : 0; |
1452 | char tbuf[16]; |
1453 | |
1454 | sprintf(buf: tbuf, fmt: "%pI4", n->key); |
1455 | seq_printf(m: seq, fmt: "%-16s 0x%-10x0x%-10x%s * %s\n", |
1456 | tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00", |
1457 | dev ? dev->name : "*"); |
1458 | } |
1459 | |
1460 | static int arp_seq_show(struct seq_file *seq, void *v) |
1461 | { |
1462 | if (v == SEQ_START_TOKEN) { |
1463 | seq_puts(m: seq, s: "IP address HW type Flags " |
1464 | "HW address Mask Device\n"); |
1465 | } else { |
1466 | struct neigh_seq_state *state = seq->private; |
1467 | |
1468 | if (state->flags & NEIGH_SEQ_IS_PNEIGH) |
1469 | arp_format_pneigh_entry(seq, n: v); |
1470 | else |
1471 | arp_format_neigh_entry(seq, n: v); |
1472 | } |
1473 | |
1474 | return 0; |
1475 | } |
1476 | |
1477 | static void *arp_seq_start(struct seq_file *seq, loff_t *pos) |
1478 | { |
1479 | /* Don't want to confuse "arp -a" w/ magic entries, |
1480 | * so we tell the generic iterator to skip NUD_NOARP. |
1481 | */ |
1482 | return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP); |
1483 | } |
1484 | |
1485 | static const struct seq_operations arp_seq_ops = { |
1486 | .start = arp_seq_start, |
1487 | .next = neigh_seq_next, |
1488 | .stop = neigh_seq_stop, |
1489 | .show = arp_seq_show, |
1490 | }; |
1491 | #endif /* CONFIG_PROC_FS */ |
1492 | |
1493 | static int __net_init arp_net_init(struct net *net) |
1494 | { |
1495 | if (!proc_create_net("arp", 0444, net->proc_net, &arp_seq_ops, |
1496 | sizeof(struct neigh_seq_state))) |
1497 | return -ENOMEM; |
1498 | return 0; |
1499 | } |
1500 | |
1501 | static void __net_exit arp_net_exit(struct net *net) |
1502 | { |
1503 | remove_proc_entry("arp", net->proc_net); |
1504 | } |
1505 | |
1506 | static struct pernet_operations arp_net_ops = { |
1507 | .init = arp_net_init, |
1508 | .exit = arp_net_exit, |
1509 | }; |
1510 | |
1511 | void __init arp_init(void) |
1512 | { |
1513 | neigh_table_init(index: NEIGH_ARP_TABLE, tbl: &arp_tbl); |
1514 | |
1515 | dev_add_pack(pt: &arp_packet_type); |
1516 | register_pernet_subsys(&arp_net_ops); |
1517 | #ifdef CONFIG_SYSCTL |
1518 | neigh_sysctl_register(NULL, p: &arp_tbl.parms, NULL); |
1519 | #endif |
1520 | register_netdevice_notifier(nb: &arp_netdev_notifier); |
1521 | } |
1522 |
Definitions
- arp_generic_ops
- arp_hh_ops
- arp_direct_ops
- arp_tbl
- arp_mc_map
- arp_hash
- arp_key_eq
- arp_constructor
- arp_error_report
- arp_send_dst
- arp_send
- arp_solicit
- arp_ignore
- arp_accept
- arp_filter
- arp_fwd_proxy
- arp_fwd_pvlan
- arp_create
- arp_xmit_finish
- arp_xmit
- arp_is_garp
- arp_process
- parp_redo
- arp_is_multicast
- arp_rcv
- arp_req_dev_by_name
- arp_req_dev
- arp_req_set_proxy
- arp_req_set_public
- arp_req_set
- arp_state_to_flags
- arp_req_get
- arp_invalidate
- arp_req_delete_public
- arp_req_delete
- arp_ioctl
- arp_netdev_event
- arp_netdev_notifier
- arp_ifdown
- arp_packet_type
- ax2asc2
- arp_format_neigh_entry
- arp_format_pneigh_entry
- arp_seq_show
- arp_seq_start
- arp_seq_ops
- arp_net_init
- arp_net_exit
- arp_net_ops
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