1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *  Handle bridge arp/nd proxy/suppress
4 *
5 *  Copyright (C) 2017 Cumulus Networks
6 *  Copyright (c) 2017 Roopa Prabhu <roopa@cumulusnetworks.com>
7 *
8 *  Authors:
9 *	Roopa Prabhu <roopa@cumulusnetworks.com>
10 */
11
12#include <linux/kernel.h>
13#include <linux/netdevice.h>
14#include <linux/etherdevice.h>
15#include <linux/neighbour.h>
16#include <net/arp.h>
17#include <linux/if_vlan.h>
18#include <linux/inetdevice.h>
19#include <net/addrconf.h>
20#include <net/ipv6_stubs.h>
21#if IS_ENABLED(CONFIG_IPV6)
22#include <net/ip6_checksum.h>
23#endif
24
25#include "br_private.h"
26
27void br_recalculate_neigh_suppress_enabled(struct net_bridge *br)
28{
29	struct net_bridge_port *p;
30	bool neigh_suppress = false;
31
32	list_for_each_entry(p, &br->port_list, list) {
33		if (p->flags & (BR_NEIGH_SUPPRESS | BR_NEIGH_VLAN_SUPPRESS)) {
34			neigh_suppress = true;
35			break;
36		}
37	}
38
39	br_opt_toggle(br, BROPT_NEIGH_SUPPRESS_ENABLED, neigh_suppress);
40}
41
42#if IS_ENABLED(CONFIG_INET)
43static void br_arp_send(struct net_bridge *br, struct net_bridge_port *p,
44			struct net_device *dev, __be32 dest_ip, __be32 src_ip,
45			const unsigned char *dest_hw,
46			const unsigned char *src_hw,
47			const unsigned char *target_hw,
48			__be16 vlan_proto, u16 vlan_tci)
49{
50	struct net_bridge_vlan_group *vg;
51	struct sk_buff *skb;
52	u16 pvid;
53
54	netdev_dbg(dev, "arp send dev %s dst %pI4 dst_hw %pM src %pI4 src_hw %pM\n",
55		   dev->name, &dest_ip, dest_hw, &src_ip, src_hw);
56
57	if (!vlan_tci) {
58		arp_send(ARPOP_REPLY, ETH_P_ARP, dest_ip, dev, src_ip,
59			 dest_hw, src_hw, target_hw);
60		return;
61	}
62
63	skb = arp_create(ARPOP_REPLY, ETH_P_ARP, dest_ip, dev, src_ip,
64			 dest_hw, src_hw, target_hw);
65	if (!skb)
66		return;
67
68	if (p)
69		vg = nbp_vlan_group_rcu(p);
70	else
71		vg = br_vlan_group_rcu(br);
72	pvid = br_get_pvid(vg);
73	if (pvid == (vlan_tci & VLAN_VID_MASK))
74		vlan_tci = 0;
75
76	if (vlan_tci)
77		__vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
78
79	if (p) {
80		arp_xmit(skb);
81	} else {
82		skb_reset_mac_header(skb);
83		__skb_pull(skb, skb_network_offset(skb));
84		skb->ip_summed = CHECKSUM_UNNECESSARY;
85		skb->pkt_type = PACKET_HOST;
86
87		netif_rx(skb);
88	}
89}
90
91static int br_chk_addr_ip(struct net_device *dev,
92			  struct netdev_nested_priv *priv)
93{
94	__be32 ip = *(__be32 *)priv->data;
95	struct in_device *in_dev;
96	__be32 addr = 0;
97
98	in_dev = __in_dev_get_rcu(dev);
99	if (in_dev)
100		addr = inet_confirm_addr(dev_net(dev), in_dev, 0, ip,
101					 RT_SCOPE_HOST);
102
103	if (addr == ip)
104		return 1;
105
106	return 0;
107}
108
109static bool br_is_local_ip(struct net_device *dev, __be32 ip)
110{
111	struct netdev_nested_priv priv = {
112		.data = (void *)&ip,
113	};
114
115	if (br_chk_addr_ip(dev, &priv))
116		return true;
117
118	/* check if ip is configured on upper dev */
119	if (netdev_walk_all_upper_dev_rcu(dev, br_chk_addr_ip, &priv))
120		return true;
121
122	return false;
123}
124
125void br_do_proxy_suppress_arp(struct sk_buff *skb, struct net_bridge *br,
126			      u16 vid, struct net_bridge_port *p)
127{
128	struct net_device *dev = br->dev;
129	struct net_device *vlandev = dev;
130	struct neighbour *n;
131	struct arphdr *parp;
132	u8 *arpptr, *sha;
133	__be32 sip, tip;
134
135	BR_INPUT_SKB_CB(skb)->proxyarp_replied = 0;
136
137	if ((dev->flags & IFF_NOARP) ||
138	    !pskb_may_pull(skb, arp_hdr_len(dev)))
139		return;
140
141	parp = arp_hdr(skb);
142
143	if (parp->ar_pro != htons(ETH_P_IP) ||
144	    parp->ar_hln != dev->addr_len ||
145	    parp->ar_pln != 4)
146		return;
147
148	arpptr = (u8 *)parp + sizeof(struct arphdr);
149	sha = arpptr;
150	arpptr += dev->addr_len;	/* sha */
151	memcpy(&sip, arpptr, sizeof(sip));
152	arpptr += sizeof(sip);
153	arpptr += dev->addr_len;	/* tha */
154	memcpy(&tip, arpptr, sizeof(tip));
155
156	if (ipv4_is_loopback(tip) ||
157	    ipv4_is_multicast(tip))
158		return;
159
160	if (br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED)) {
161		if (br_is_neigh_suppress_enabled(p, vid))
162			return;
163		if (parp->ar_op != htons(ARPOP_RREQUEST) &&
164		    parp->ar_op != htons(ARPOP_RREPLY) &&
165		    (ipv4_is_zeronet(sip) || sip == tip)) {
166			/* prevent flooding to neigh suppress ports */
167			BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
168			return;
169		}
170	}
171
172	if (parp->ar_op != htons(ARPOP_REQUEST))
173		return;
174
175	if (vid != 0) {
176		vlandev = __vlan_find_dev_deep_rcu(br->dev, skb->vlan_proto,
177						   vid);
178		if (!vlandev)
179			return;
180	}
181
182	if (br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) &&
183	    br_is_local_ip(vlandev, tip)) {
184		/* its our local ip, so don't proxy reply
185		 * and don't forward to neigh suppress ports
186		 */
187		BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
188		return;
189	}
190
191	n = neigh_lookup(&arp_tbl, &tip, vlandev);
192	if (n) {
193		struct net_bridge_fdb_entry *f;
194
195		if (!(READ_ONCE(n->nud_state) & NUD_VALID)) {
196			neigh_release(n);
197			return;
198		}
199
200		f = br_fdb_find_rcu(br, n->ha, vid);
201		if (f) {
202			bool replied = false;
203
204			if ((p && (p->flags & BR_PROXYARP)) ||
205			    (f->dst && (f->dst->flags & BR_PROXYARP_WIFI)) ||
206			    br_is_neigh_suppress_enabled(f->dst, vid)) {
207				if (!vid)
208					br_arp_send(br, p, skb->dev, sip, tip,
209						    sha, n->ha, sha, 0, 0);
210				else
211					br_arp_send(br, p, skb->dev, sip, tip,
212						    sha, n->ha, sha,
213						    skb->vlan_proto,
214						    skb_vlan_tag_get(skb));
215				replied = true;
216			}
217
218			/* If we have replied or as long as we know the
219			 * mac, indicate to arp replied
220			 */
221			if (replied ||
222			    br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED))
223				BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
224		}
225
226		neigh_release(n);
227	}
228}
229#endif
230
231#if IS_ENABLED(CONFIG_IPV6)
232struct nd_msg *br_is_nd_neigh_msg(struct sk_buff *skb, struct nd_msg *msg)
233{
234	struct nd_msg *m;
235
236	m = skb_header_pointer(skb, skb_network_offset(skb) +
237			       sizeof(struct ipv6hdr), sizeof(*msg), msg);
238	if (!m)
239		return NULL;
240
241	if (m->icmph.icmp6_code != 0 ||
242	    (m->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION &&
243	     m->icmph.icmp6_type != NDISC_NEIGHBOUR_ADVERTISEMENT))
244		return NULL;
245
246	return m;
247}
248
249static void br_nd_send(struct net_bridge *br, struct net_bridge_port *p,
250		       struct sk_buff *request, struct neighbour *n,
251		       __be16 vlan_proto, u16 vlan_tci, struct nd_msg *ns)
252{
253	struct net_device *dev = request->dev;
254	struct net_bridge_vlan_group *vg;
255	struct sk_buff *reply;
256	struct nd_msg *na;
257	struct ipv6hdr *pip6;
258	int na_olen = 8; /* opt hdr + ETH_ALEN for target */
259	int ns_olen;
260	int i, len;
261	u8 *daddr;
262	u16 pvid;
263
264	if (!dev)
265		return;
266
267	len = LL_RESERVED_SPACE(dev) + sizeof(struct ipv6hdr) +
268		sizeof(*na) + na_olen + dev->needed_tailroom;
269
270	reply = alloc_skb(len, GFP_ATOMIC);
271	if (!reply)
272		return;
273
274	reply->protocol = htons(ETH_P_IPV6);
275	reply->dev = dev;
276	skb_reserve(reply, LL_RESERVED_SPACE(dev));
277	skb_push(reply, sizeof(struct ethhdr));
278	skb_set_mac_header(reply, 0);
279
280	daddr = eth_hdr(request)->h_source;
281
282	/* Do we need option processing ? */
283	ns_olen = request->len - (skb_network_offset(request) +
284				  sizeof(struct ipv6hdr)) - sizeof(*ns);
285	for (i = 0; i < ns_olen - 1; i += (ns->opt[i + 1] << 3)) {
286		if (!ns->opt[i + 1]) {
287			kfree_skb(reply);
288			return;
289		}
290		if (ns->opt[i] == ND_OPT_SOURCE_LL_ADDR) {
291			daddr = ns->opt + i + sizeof(struct nd_opt_hdr);
292			break;
293		}
294	}
295
296	/* Ethernet header */
297	ether_addr_copy(eth_hdr(reply)->h_dest, daddr);
298	ether_addr_copy(eth_hdr(reply)->h_source, n->ha);
299	eth_hdr(reply)->h_proto = htons(ETH_P_IPV6);
300	reply->protocol = htons(ETH_P_IPV6);
301
302	skb_pull(reply, sizeof(struct ethhdr));
303	skb_set_network_header(reply, 0);
304	skb_put(reply, sizeof(struct ipv6hdr));
305
306	/* IPv6 header */
307	pip6 = ipv6_hdr(reply);
308	memset(pip6, 0, sizeof(struct ipv6hdr));
309	pip6->version = 6;
310	pip6->priority = ipv6_hdr(request)->priority;
311	pip6->nexthdr = IPPROTO_ICMPV6;
312	pip6->hop_limit = 255;
313	pip6->daddr = ipv6_hdr(request)->saddr;
314	pip6->saddr = *(struct in6_addr *)n->primary_key;
315
316	skb_pull(reply, sizeof(struct ipv6hdr));
317	skb_set_transport_header(reply, 0);
318
319	na = (struct nd_msg *)skb_put(reply, sizeof(*na) + na_olen);
320
321	/* Neighbor Advertisement */
322	memset(na, 0, sizeof(*na) + na_olen);
323	na->icmph.icmp6_type = NDISC_NEIGHBOUR_ADVERTISEMENT;
324	na->icmph.icmp6_router = (n->flags & NTF_ROUTER) ? 1 : 0;
325	na->icmph.icmp6_override = 1;
326	na->icmph.icmp6_solicited = 1;
327	na->target = ns->target;
328	ether_addr_copy(&na->opt[2], n->ha);
329	na->opt[0] = ND_OPT_TARGET_LL_ADDR;
330	na->opt[1] = na_olen >> 3;
331
332	na->icmph.icmp6_cksum = csum_ipv6_magic(&pip6->saddr,
333						&pip6->daddr,
334						sizeof(*na) + na_olen,
335						IPPROTO_ICMPV6,
336						csum_partial(na, sizeof(*na) + na_olen, 0));
337
338	pip6->payload_len = htons(sizeof(*na) + na_olen);
339
340	skb_push(reply, sizeof(struct ipv6hdr));
341	skb_push(reply, sizeof(struct ethhdr));
342
343	reply->ip_summed = CHECKSUM_UNNECESSARY;
344
345	if (p)
346		vg = nbp_vlan_group_rcu(p);
347	else
348		vg = br_vlan_group_rcu(br);
349	pvid = br_get_pvid(vg);
350	if (pvid == (vlan_tci & VLAN_VID_MASK))
351		vlan_tci = 0;
352
353	if (vlan_tci)
354		__vlan_hwaccel_put_tag(reply, vlan_proto, vlan_tci);
355
356	netdev_dbg(dev, "nd send dev %s dst %pI6 dst_hw %pM src %pI6 src_hw %pM\n",
357		   dev->name, &pip6->daddr, daddr, &pip6->saddr, n->ha);
358
359	if (p) {
360		dev_queue_xmit(reply);
361	} else {
362		skb_reset_mac_header(reply);
363		__skb_pull(reply, skb_network_offset(reply));
364		reply->ip_summed = CHECKSUM_UNNECESSARY;
365		reply->pkt_type = PACKET_HOST;
366
367		netif_rx(reply);
368	}
369}
370
371static int br_chk_addr_ip6(struct net_device *dev,
372			   struct netdev_nested_priv *priv)
373{
374	struct in6_addr *addr = (struct in6_addr *)priv->data;
375
376	if (ipv6_chk_addr(dev_net(dev), addr, dev, 0))
377		return 1;
378
379	return 0;
380}
381
382static bool br_is_local_ip6(struct net_device *dev, struct in6_addr *addr)
383
384{
385	struct netdev_nested_priv priv = {
386		.data = (void *)addr,
387	};
388
389	if (br_chk_addr_ip6(dev, &priv))
390		return true;
391
392	/* check if ip is configured on upper dev */
393	if (netdev_walk_all_upper_dev_rcu(dev, br_chk_addr_ip6, &priv))
394		return true;
395
396	return false;
397}
398
399void br_do_suppress_nd(struct sk_buff *skb, struct net_bridge *br,
400		       u16 vid, struct net_bridge_port *p, struct nd_msg *msg)
401{
402	struct net_device *dev = br->dev;
403	struct net_device *vlandev = NULL;
404	struct in6_addr *saddr, *daddr;
405	struct ipv6hdr *iphdr;
406	struct neighbour *n;
407
408	BR_INPUT_SKB_CB(skb)->proxyarp_replied = 0;
409
410	if (br_is_neigh_suppress_enabled(p, vid))
411		return;
412
413	if (msg->icmph.icmp6_type == NDISC_NEIGHBOUR_ADVERTISEMENT &&
414	    !msg->icmph.icmp6_solicited) {
415		/* prevent flooding to neigh suppress ports */
416		BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
417		return;
418	}
419
420	if (msg->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION)
421		return;
422
423	iphdr = ipv6_hdr(skb);
424	saddr = &iphdr->saddr;
425	daddr = &iphdr->daddr;
426
427	if (ipv6_addr_any(saddr) || !ipv6_addr_cmp(saddr, daddr)) {
428		/* prevent flooding to neigh suppress ports */
429		BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
430		return;
431	}
432
433	if (vid != 0) {
434		/* build neigh table lookup on the vlan device */
435		vlandev = __vlan_find_dev_deep_rcu(br->dev, skb->vlan_proto,
436						   vid);
437		if (!vlandev)
438			return;
439	} else {
440		vlandev = dev;
441	}
442
443	if (br_is_local_ip6(vlandev, &msg->target)) {
444		/* its our own ip, so don't proxy reply
445		 * and don't forward to arp suppress ports
446		 */
447		BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
448		return;
449	}
450
451	n = neigh_lookup(ipv6_stub->nd_tbl, &msg->target, vlandev);
452	if (n) {
453		struct net_bridge_fdb_entry *f;
454
455		if (!(READ_ONCE(n->nud_state) & NUD_VALID)) {
456			neigh_release(n);
457			return;
458		}
459
460		f = br_fdb_find_rcu(br, n->ha, vid);
461		if (f) {
462			bool replied = false;
463
464			if (br_is_neigh_suppress_enabled(f->dst, vid)) {
465				if (vid != 0)
466					br_nd_send(br, p, skb, n,
467						   skb->vlan_proto,
468						   skb_vlan_tag_get(skb), msg);
469				else
470					br_nd_send(br, p, skb, n, 0, 0, msg);
471				replied = true;
472			}
473
474			/* If we have replied or as long as we know the
475			 * mac, indicate to NEIGH_SUPPRESS ports that we
476			 * have replied
477			 */
478			if (replied ||
479			    br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED))
480				BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
481		}
482		neigh_release(n);
483	}
484}
485#endif
486
487bool br_is_neigh_suppress_enabled(const struct net_bridge_port *p, u16 vid)
488{
489	if (!p)
490		return false;
491
492	if (!vid)
493		return !!(p->flags & BR_NEIGH_SUPPRESS);
494
495	if (p->flags & BR_NEIGH_VLAN_SUPPRESS) {
496		struct net_bridge_vlan_group *vg = nbp_vlan_group_rcu(p);
497		struct net_bridge_vlan *v;
498
499		v = br_vlan_find(vg, vid);
500		if (!v)
501			return false;
502		return !!(v->priv_flags & BR_VLFLAG_NEIGH_SUPPRESS_ENABLED);
503	} else {
504		return !!(p->flags & BR_NEIGH_SUPPRESS);
505	}
506}
507