1 /*
2 * Handle bridge arp/nd proxy/suppress
3 *
4 * Copyright (C) 2017 Cumulus Networks
5 * Copyright (c) 2017 Roopa Prabhu <roopa@cumulusnetworks.com>
6 *
7 * Authors:
8 * Roopa Prabhu <roopa@cumulusnetworks.com>
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version
13 * 2 of the License, or (at your option) any later version.
14 */
15
16 #include <linux/kernel.h>
17 #include <linux/netdevice.h>
18 #include <linux/etherdevice.h>
19 #include <linux/neighbour.h>
20 #include <net/arp.h>
21 #include <linux/if_vlan.h>
22 #include <linux/inetdevice.h>
23 #include <net/addrconf.h>
24 #if IS_ENABLED(CONFIG_IPV6)
25 #include <net/ip6_checksum.h>
26 #endif
27
28 #include "br_private.h"
29
br_recalculate_neigh_suppress_enabled(struct net_bridge * br)30 void br_recalculate_neigh_suppress_enabled(struct net_bridge *br)
31 {
32 struct net_bridge_port *p;
33 bool neigh_suppress = false;
34
35 list_for_each_entry(p, &br->port_list, list) {
36 if (p->flags & BR_NEIGH_SUPPRESS) {
37 neigh_suppress = true;
38 break;
39 }
40 }
41
42 br->neigh_suppress_enabled = neigh_suppress;
43 }
44
45 #if IS_ENABLED(CONFIG_INET)
br_arp_send(struct net_bridge * br,struct net_bridge_port * p,struct net_device * dev,__be32 dest_ip,__be32 src_ip,const unsigned char * dest_hw,const unsigned char * src_hw,const unsigned char * target_hw,__be16 vlan_proto,u16 vlan_tci)46 static void br_arp_send(struct net_bridge *br, struct net_bridge_port *p,
47 struct net_device *dev, __be32 dest_ip, __be32 src_ip,
48 const unsigned char *dest_hw,
49 const unsigned char *src_hw,
50 const unsigned char *target_hw,
51 __be16 vlan_proto, u16 vlan_tci)
52 {
53 struct net_bridge_vlan_group *vg;
54 struct sk_buff *skb;
55 u16 pvid;
56
57 netdev_dbg(dev, "arp send dev %s dst %pI4 dst_hw %pM src %pI4 src_hw %pM\n",
58 dev->name, &dest_ip, dest_hw, &src_ip, src_hw);
59
60 if (!vlan_tci) {
61 arp_send(ARPOP_REPLY, ETH_P_ARP, dest_ip, dev, src_ip,
62 dest_hw, src_hw, target_hw);
63 return;
64 }
65
66 skb = arp_create(ARPOP_REPLY, ETH_P_ARP, dest_ip, dev, src_ip,
67 dest_hw, src_hw, target_hw);
68 if (!skb)
69 return;
70
71 if (p)
72 vg = nbp_vlan_group_rcu(p);
73 else
74 vg = br_vlan_group_rcu(br);
75 pvid = br_get_pvid(vg);
76 if (pvid == (vlan_tci & VLAN_VID_MASK))
77 vlan_tci = 0;
78
79 if (vlan_tci)
80 __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
81
82 if (p) {
83 arp_xmit(skb);
84 } else {
85 skb_reset_mac_header(skb);
86 __skb_pull(skb, skb_network_offset(skb));
87 skb->ip_summed = CHECKSUM_UNNECESSARY;
88 skb->pkt_type = PACKET_HOST;
89
90 netif_rx_ni(skb);
91 }
92 }
93
br_chk_addr_ip(struct net_device * dev,void * data)94 static int br_chk_addr_ip(struct net_device *dev, void *data)
95 {
96 __be32 ip = *(__be32 *)data;
97 struct in_device *in_dev;
98 __be32 addr = 0;
99
100 in_dev = __in_dev_get_rcu(dev);
101 if (in_dev)
102 addr = inet_confirm_addr(dev_net(dev), in_dev, 0, ip,
103 RT_SCOPE_HOST);
104
105 if (addr == ip)
106 return 1;
107
108 return 0;
109 }
110
br_is_local_ip(struct net_device * dev,__be32 ip)111 static bool br_is_local_ip(struct net_device *dev, __be32 ip)
112 {
113 if (br_chk_addr_ip(dev, &ip))
114 return true;
115
116 /* check if ip is configured on upper dev */
117 if (netdev_walk_all_upper_dev_rcu(dev, br_chk_addr_ip, &ip))
118 return true;
119
120 return false;
121 }
122
br_do_proxy_suppress_arp(struct sk_buff * skb,struct net_bridge * br,u16 vid,struct net_bridge_port * p)123 void br_do_proxy_suppress_arp(struct sk_buff *skb, struct net_bridge *br,
124 u16 vid, struct net_bridge_port *p)
125 {
126 struct net_device *dev = br->dev;
127 struct net_device *vlandev = dev;
128 struct neighbour *n;
129 struct arphdr *parp;
130 u8 *arpptr, *sha;
131 __be32 sip, tip;
132
133 BR_INPUT_SKB_CB(skb)->proxyarp_replied = false;
134
135 if ((dev->flags & IFF_NOARP) ||
136 !pskb_may_pull(skb, arp_hdr_len(dev)))
137 return;
138
139 parp = arp_hdr(skb);
140
141 if (parp->ar_pro != htons(ETH_P_IP) ||
142 parp->ar_hln != dev->addr_len ||
143 parp->ar_pln != 4)
144 return;
145
146 arpptr = (u8 *)parp + sizeof(struct arphdr);
147 sha = arpptr;
148 arpptr += dev->addr_len; /* sha */
149 memcpy(&sip, arpptr, sizeof(sip));
150 arpptr += sizeof(sip);
151 arpptr += dev->addr_len; /* tha */
152 memcpy(&tip, arpptr, sizeof(tip));
153
154 if (ipv4_is_loopback(tip) ||
155 ipv4_is_multicast(tip))
156 return;
157
158 if (br->neigh_suppress_enabled) {
159 if (p && (p->flags & BR_NEIGH_SUPPRESS))
160 return;
161 if (ipv4_is_zeronet(sip) || sip == tip) {
162 /* prevent flooding to neigh suppress ports */
163 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
164 return;
165 }
166 }
167
168 if (parp->ar_op != htons(ARPOP_REQUEST))
169 return;
170
171 if (vid != 0) {
172 vlandev = __vlan_find_dev_deep_rcu(br->dev, skb->vlan_proto,
173 vid);
174 if (!vlandev)
175 return;
176 }
177
178 if (br->neigh_suppress_enabled && br_is_local_ip(vlandev, tip)) {
179 /* its our local ip, so don't proxy reply
180 * and don't forward to neigh suppress ports
181 */
182 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
183 return;
184 }
185
186 n = neigh_lookup(&arp_tbl, &tip, vlandev);
187 if (n) {
188 struct net_bridge_fdb_entry *f;
189
190 if (!(n->nud_state & NUD_VALID)) {
191 neigh_release(n);
192 return;
193 }
194
195 f = br_fdb_find_rcu(br, n->ha, vid);
196 if (f) {
197 bool replied = false;
198
199 if ((p && (p->flags & BR_PROXYARP)) ||
200 (f->dst && (f->dst->flags & (BR_PROXYARP_WIFI |
201 BR_NEIGH_SUPPRESS)))) {
202 if (!vid)
203 br_arp_send(br, p, skb->dev, sip, tip,
204 sha, n->ha, sha, 0, 0);
205 else
206 br_arp_send(br, p, skb->dev, sip, tip,
207 sha, n->ha, sha,
208 skb->vlan_proto,
209 skb_vlan_tag_get(skb));
210 replied = true;
211 }
212
213 /* If we have replied or as long as we know the
214 * mac, indicate to arp replied
215 */
216 if (replied || br->neigh_suppress_enabled)
217 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
218 }
219
220 neigh_release(n);
221 }
222 }
223 #endif
224
225 #if IS_ENABLED(CONFIG_IPV6)
br_is_nd_neigh_msg(struct sk_buff * skb,struct nd_msg * msg)226 struct nd_msg *br_is_nd_neigh_msg(struct sk_buff *skb, struct nd_msg *msg)
227 {
228 struct nd_msg *m;
229
230 m = skb_header_pointer(skb, skb_network_offset(skb) +
231 sizeof(struct ipv6hdr), sizeof(*msg), msg);
232 if (!m)
233 return NULL;
234
235 if (m->icmph.icmp6_code != 0 ||
236 (m->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION &&
237 m->icmph.icmp6_type != NDISC_NEIGHBOUR_ADVERTISEMENT))
238 return NULL;
239
240 return m;
241 }
242
br_nd_send(struct net_bridge * br,struct net_bridge_port * p,struct sk_buff * request,struct neighbour * n,__be16 vlan_proto,u16 vlan_tci,struct nd_msg * ns)243 static void br_nd_send(struct net_bridge *br, struct net_bridge_port *p,
244 struct sk_buff *request, struct neighbour *n,
245 __be16 vlan_proto, u16 vlan_tci, struct nd_msg *ns)
246 {
247 struct net_device *dev = request->dev;
248 struct net_bridge_vlan_group *vg;
249 struct sk_buff *reply;
250 struct nd_msg *na;
251 struct ipv6hdr *pip6;
252 int na_olen = 8; /* opt hdr + ETH_ALEN for target */
253 int ns_olen;
254 int i, len;
255 u8 *daddr;
256 u16 pvid;
257
258 if (!dev)
259 return;
260
261 len = LL_RESERVED_SPACE(dev) + sizeof(struct ipv6hdr) +
262 sizeof(*na) + na_olen + dev->needed_tailroom;
263
264 reply = alloc_skb(len, GFP_ATOMIC);
265 if (!reply)
266 return;
267
268 reply->protocol = htons(ETH_P_IPV6);
269 reply->dev = dev;
270 skb_reserve(reply, LL_RESERVED_SPACE(dev));
271 skb_push(reply, sizeof(struct ethhdr));
272 skb_set_mac_header(reply, 0);
273
274 daddr = eth_hdr(request)->h_source;
275
276 /* Do we need option processing ? */
277 ns_olen = request->len - (skb_network_offset(request) +
278 sizeof(struct ipv6hdr)) - sizeof(*ns);
279 for (i = 0; i < ns_olen - 1; i += (ns->opt[i + 1] << 3)) {
280 if (ns->opt[i] == ND_OPT_SOURCE_LL_ADDR) {
281 daddr = ns->opt + i + sizeof(struct nd_opt_hdr);
282 break;
283 }
284 }
285
286 /* Ethernet header */
287 ether_addr_copy(eth_hdr(reply)->h_dest, daddr);
288 ether_addr_copy(eth_hdr(reply)->h_source, n->ha);
289 eth_hdr(reply)->h_proto = htons(ETH_P_IPV6);
290 reply->protocol = htons(ETH_P_IPV6);
291
292 skb_pull(reply, sizeof(struct ethhdr));
293 skb_set_network_header(reply, 0);
294 skb_put(reply, sizeof(struct ipv6hdr));
295
296 /* IPv6 header */
297 pip6 = ipv6_hdr(reply);
298 memset(pip6, 0, sizeof(struct ipv6hdr));
299 pip6->version = 6;
300 pip6->priority = ipv6_hdr(request)->priority;
301 pip6->nexthdr = IPPROTO_ICMPV6;
302 pip6->hop_limit = 255;
303 pip6->daddr = ipv6_hdr(request)->saddr;
304 pip6->saddr = *(struct in6_addr *)n->primary_key;
305
306 skb_pull(reply, sizeof(struct ipv6hdr));
307 skb_set_transport_header(reply, 0);
308
309 na = (struct nd_msg *)skb_put(reply, sizeof(*na) + na_olen);
310
311 /* Neighbor Advertisement */
312 memset(na, 0, sizeof(*na) + na_olen);
313 na->icmph.icmp6_type = NDISC_NEIGHBOUR_ADVERTISEMENT;
314 na->icmph.icmp6_router = 0; /* XXX: should be 1 ? */
315 na->icmph.icmp6_override = 1;
316 na->icmph.icmp6_solicited = 1;
317 na->target = ns->target;
318 ether_addr_copy(&na->opt[2], n->ha);
319 na->opt[0] = ND_OPT_TARGET_LL_ADDR;
320 na->opt[1] = na_olen >> 3;
321
322 na->icmph.icmp6_cksum = csum_ipv6_magic(&pip6->saddr,
323 &pip6->daddr,
324 sizeof(*na) + na_olen,
325 IPPROTO_ICMPV6,
326 csum_partial(na, sizeof(*na) + na_olen, 0));
327
328 pip6->payload_len = htons(sizeof(*na) + na_olen);
329
330 skb_push(reply, sizeof(struct ipv6hdr));
331 skb_push(reply, sizeof(struct ethhdr));
332
333 reply->ip_summed = CHECKSUM_UNNECESSARY;
334
335 if (p)
336 vg = nbp_vlan_group_rcu(p);
337 else
338 vg = br_vlan_group_rcu(br);
339 pvid = br_get_pvid(vg);
340 if (pvid == (vlan_tci & VLAN_VID_MASK))
341 vlan_tci = 0;
342
343 if (vlan_tci)
344 __vlan_hwaccel_put_tag(reply, vlan_proto, vlan_tci);
345
346 netdev_dbg(dev, "nd send dev %s dst %pI6 dst_hw %pM src %pI6 src_hw %pM\n",
347 dev->name, &pip6->daddr, daddr, &pip6->saddr, n->ha);
348
349 if (p) {
350 dev_queue_xmit(reply);
351 } else {
352 skb_reset_mac_header(reply);
353 __skb_pull(reply, skb_network_offset(reply));
354 reply->ip_summed = CHECKSUM_UNNECESSARY;
355 reply->pkt_type = PACKET_HOST;
356
357 netif_rx_ni(reply);
358 }
359 }
360
br_chk_addr_ip6(struct net_device * dev,void * data)361 static int br_chk_addr_ip6(struct net_device *dev, void *data)
362 {
363 struct in6_addr *addr = (struct in6_addr *)data;
364
365 if (ipv6_chk_addr(dev_net(dev), addr, dev, 0))
366 return 1;
367
368 return 0;
369 }
370
br_is_local_ip6(struct net_device * dev,struct in6_addr * addr)371 static bool br_is_local_ip6(struct net_device *dev, struct in6_addr *addr)
372
373 {
374 if (br_chk_addr_ip6(dev, addr))
375 return true;
376
377 /* check if ip is configured on upper dev */
378 if (netdev_walk_all_upper_dev_rcu(dev, br_chk_addr_ip6, addr))
379 return true;
380
381 return false;
382 }
383
br_do_suppress_nd(struct sk_buff * skb,struct net_bridge * br,u16 vid,struct net_bridge_port * p,struct nd_msg * msg)384 void br_do_suppress_nd(struct sk_buff *skb, struct net_bridge *br,
385 u16 vid, struct net_bridge_port *p, struct nd_msg *msg)
386 {
387 struct net_device *dev = br->dev;
388 struct net_device *vlandev = NULL;
389 struct in6_addr *saddr, *daddr;
390 struct ipv6hdr *iphdr;
391 struct neighbour *n;
392
393 BR_INPUT_SKB_CB(skb)->proxyarp_replied = false;
394
395 if (p && (p->flags & BR_NEIGH_SUPPRESS))
396 return;
397
398 if (msg->icmph.icmp6_type == NDISC_NEIGHBOUR_ADVERTISEMENT &&
399 !msg->icmph.icmp6_solicited) {
400 /* prevent flooding to neigh suppress ports */
401 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
402 return;
403 }
404
405 if (msg->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION)
406 return;
407
408 iphdr = ipv6_hdr(skb);
409 saddr = &iphdr->saddr;
410 daddr = &iphdr->daddr;
411
412 if (ipv6_addr_any(saddr) || !ipv6_addr_cmp(saddr, daddr)) {
413 /* prevent flooding to neigh suppress ports */
414 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
415 return;
416 }
417
418 if (vid != 0) {
419 /* build neigh table lookup on the vlan device */
420 vlandev = __vlan_find_dev_deep_rcu(br->dev, skb->vlan_proto,
421 vid);
422 if (!vlandev)
423 return;
424 } else {
425 vlandev = dev;
426 }
427
428 if (br_is_local_ip6(vlandev, &msg->target)) {
429 /* its our own ip, so don't proxy reply
430 * and don't forward to arp suppress ports
431 */
432 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
433 return;
434 }
435
436 n = neigh_lookup(ipv6_stub->nd_tbl, &msg->target, vlandev);
437 if (n) {
438 struct net_bridge_fdb_entry *f;
439
440 if (!(n->nud_state & NUD_VALID)) {
441 neigh_release(n);
442 return;
443 }
444
445 f = br_fdb_find_rcu(br, n->ha, vid);
446 if (f) {
447 bool replied = false;
448
449 if (f->dst && (f->dst->flags & BR_NEIGH_SUPPRESS)) {
450 if (vid != 0)
451 br_nd_send(br, p, skb, n,
452 skb->vlan_proto,
453 skb_vlan_tag_get(skb), msg);
454 else
455 br_nd_send(br, p, skb, n, 0, 0, msg);
456 replied = true;
457 }
458
459 /* If we have replied or as long as we know the
460 * mac, indicate to NEIGH_SUPPRESS ports that we
461 * have replied
462 */
463 if (replied || br->neigh_suppress_enabled)
464 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
465 }
466 neigh_release(n);
467 }
468 }
469 #endif
470
