xref: /openbmc/linux/net/bridge/br_input.c (revision 7bcae826)
1 /*
2  *	Handle incoming frames
3  *	Linux ethernet bridge
4  *
5  *	Authors:
6  *	Lennert Buytenhek		<buytenh@gnu.org>
7  *
8  *	This program is free software; you can redistribute it and/or
9  *	modify it under the terms of the GNU General Public License
10  *	as published by the Free Software Foundation; either version
11  *	2 of the License, or (at your option) any later version.
12  */
13 
14 #include <linux/slab.h>
15 #include <linux/kernel.h>
16 #include <linux/netdevice.h>
17 #include <linux/etherdevice.h>
18 #include <linux/netfilter_bridge.h>
19 #include <linux/neighbour.h>
20 #include <net/arp.h>
21 #include <linux/export.h>
22 #include <linux/rculist.h>
23 #include "br_private.h"
24 #include "br_private_tunnel.h"
25 
26 /* Hook for brouter */
27 br_should_route_hook_t __rcu *br_should_route_hook __read_mostly;
28 EXPORT_SYMBOL(br_should_route_hook);
29 
30 static int
31 br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
32 {
33 	return netif_receive_skb(skb);
34 }
35 
36 static int br_pass_frame_up(struct sk_buff *skb)
37 {
38 	struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
39 	struct net_bridge *br = netdev_priv(brdev);
40 	struct net_bridge_vlan_group *vg;
41 	struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
42 
43 	u64_stats_update_begin(&brstats->syncp);
44 	brstats->rx_packets++;
45 	brstats->rx_bytes += skb->len;
46 	u64_stats_update_end(&brstats->syncp);
47 
48 	vg = br_vlan_group_rcu(br);
49 	/* Bridge is just like any other port.  Make sure the
50 	 * packet is allowed except in promisc modue when someone
51 	 * may be running packet capture.
52 	 */
53 	if (!(brdev->flags & IFF_PROMISC) &&
54 	    !br_allowed_egress(vg, skb)) {
55 		kfree_skb(skb);
56 		return NET_RX_DROP;
57 	}
58 
59 	indev = skb->dev;
60 	skb->dev = brdev;
61 	skb = br_handle_vlan(br, NULL, vg, skb);
62 	if (!skb)
63 		return NET_RX_DROP;
64 	/* update the multicast stats if the packet is IGMP/MLD */
65 	br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb),
66 			   BR_MCAST_DIR_TX);
67 
68 	return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
69 		       dev_net(indev), NULL, skb, indev, NULL,
70 		       br_netif_receive_skb);
71 }
72 
73 static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br,
74 			    u16 vid, struct net_bridge_port *p)
75 {
76 	struct net_device *dev = br->dev;
77 	struct neighbour *n;
78 	struct arphdr *parp;
79 	u8 *arpptr, *sha;
80 	__be32 sip, tip;
81 
82 	BR_INPUT_SKB_CB(skb)->proxyarp_replied = false;
83 
84 	if ((dev->flags & IFF_NOARP) ||
85 	    !pskb_may_pull(skb, arp_hdr_len(dev)))
86 		return;
87 
88 	parp = arp_hdr(skb);
89 
90 	if (parp->ar_pro != htons(ETH_P_IP) ||
91 	    parp->ar_op != htons(ARPOP_REQUEST) ||
92 	    parp->ar_hln != dev->addr_len ||
93 	    parp->ar_pln != 4)
94 		return;
95 
96 	arpptr = (u8 *)parp + sizeof(struct arphdr);
97 	sha = arpptr;
98 	arpptr += dev->addr_len;	/* sha */
99 	memcpy(&sip, arpptr, sizeof(sip));
100 	arpptr += sizeof(sip);
101 	arpptr += dev->addr_len;	/* tha */
102 	memcpy(&tip, arpptr, sizeof(tip));
103 
104 	if (ipv4_is_loopback(tip) ||
105 	    ipv4_is_multicast(tip))
106 		return;
107 
108 	n = neigh_lookup(&arp_tbl, &tip, dev);
109 	if (n) {
110 		struct net_bridge_fdb_entry *f;
111 
112 		if (!(n->nud_state & NUD_VALID)) {
113 			neigh_release(n);
114 			return;
115 		}
116 
117 		f = br_fdb_find_rcu(br, n->ha, vid);
118 		if (f && ((p->flags & BR_PROXYARP) ||
119 			  (f->dst && (f->dst->flags & BR_PROXYARP_WIFI)))) {
120 			arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip,
121 				 sha, n->ha, sha);
122 			BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
123 		}
124 
125 		neigh_release(n);
126 	}
127 }
128 
129 /* note: already called with rcu_read_lock */
130 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
131 {
132 	struct net_bridge_port *p = br_port_get_rcu(skb->dev);
133 	const unsigned char *dest = eth_hdr(skb)->h_dest;
134 	enum br_pkt_type pkt_type = BR_PKT_UNICAST;
135 	struct net_bridge_fdb_entry *dst = NULL;
136 	struct net_bridge_mdb_entry *mdst;
137 	bool local_rcv, mcast_hit = false;
138 	struct net_bridge *br;
139 	u16 vid = 0;
140 
141 	if (!p || p->state == BR_STATE_DISABLED)
142 		goto drop;
143 
144 	if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid))
145 		goto out;
146 
147 	nbp_switchdev_frame_mark(p, skb);
148 
149 	/* insert into forwarding database after filtering to avoid spoofing */
150 	br = p->br;
151 	if (p->flags & BR_LEARNING)
152 		br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false);
153 
154 	local_rcv = !!(br->dev->flags & IFF_PROMISC);
155 	if (is_multicast_ether_addr(dest)) {
156 		/* by definition the broadcast is also a multicast address */
157 		if (is_broadcast_ether_addr(dest)) {
158 			pkt_type = BR_PKT_BROADCAST;
159 			local_rcv = true;
160 		} else {
161 			pkt_type = BR_PKT_MULTICAST;
162 			if (br_multicast_rcv(br, p, skb, vid))
163 				goto drop;
164 		}
165 	}
166 
167 	if (p->state == BR_STATE_LEARNING)
168 		goto drop;
169 
170 	BR_INPUT_SKB_CB(skb)->brdev = br->dev;
171 
172 	if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP))
173 		br_do_proxy_arp(skb, br, vid, p);
174 
175 	switch (pkt_type) {
176 	case BR_PKT_MULTICAST:
177 		mdst = br_mdb_get(br, skb, vid);
178 		if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
179 		    br_multicast_querier_exists(br, eth_hdr(skb))) {
180 			if ((mdst && mdst->mglist) ||
181 			    br_multicast_is_router(br)) {
182 				local_rcv = true;
183 				br->dev->stats.multicast++;
184 			}
185 			mcast_hit = true;
186 		} else {
187 			local_rcv = true;
188 			br->dev->stats.multicast++;
189 		}
190 		break;
191 	case BR_PKT_UNICAST:
192 		dst = br_fdb_find_rcu(br, dest, vid);
193 	default:
194 		break;
195 	}
196 
197 	if (dst) {
198 		unsigned long now = jiffies;
199 
200 		if (dst->is_local)
201 			return br_pass_frame_up(skb);
202 
203 		if (now != dst->used)
204 			dst->used = now;
205 		br_forward(dst->dst, skb, local_rcv, false);
206 	} else {
207 		if (!mcast_hit)
208 			br_flood(br, skb, pkt_type, local_rcv, false);
209 		else
210 			br_multicast_flood(mdst, skb, local_rcv, false);
211 	}
212 
213 	if (local_rcv)
214 		return br_pass_frame_up(skb);
215 
216 out:
217 	return 0;
218 drop:
219 	kfree_skb(skb);
220 	goto out;
221 }
222 EXPORT_SYMBOL_GPL(br_handle_frame_finish);
223 
224 static void __br_handle_local_finish(struct sk_buff *skb)
225 {
226 	struct net_bridge_port *p = br_port_get_rcu(skb->dev);
227 	u16 vid = 0;
228 
229 	/* check if vlan is allowed, to avoid spoofing */
230 	if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid))
231 		br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false);
232 }
233 
234 /* note: already called with rcu_read_lock */
235 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
236 {
237 	struct net_bridge_port *p = br_port_get_rcu(skb->dev);
238 
239 	__br_handle_local_finish(skb);
240 
241 	BR_INPUT_SKB_CB(skb)->brdev = p->br->dev;
242 	br_pass_frame_up(skb);
243 	return 0;
244 }
245 
246 /*
247  * Return NULL if skb is handled
248  * note: already called with rcu_read_lock
249  */
250 rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
251 {
252 	struct net_bridge_port *p;
253 	struct sk_buff *skb = *pskb;
254 	const unsigned char *dest = eth_hdr(skb)->h_dest;
255 	br_should_route_hook_t *rhook;
256 
257 	if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
258 		return RX_HANDLER_PASS;
259 
260 	if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
261 		goto drop;
262 
263 	skb = skb_share_check(skb, GFP_ATOMIC);
264 	if (!skb)
265 		return RX_HANDLER_CONSUMED;
266 
267 	p = br_port_get_rcu(skb->dev);
268 	if (p->flags & BR_VLAN_TUNNEL) {
269 		if (br_handle_ingress_vlan_tunnel(skb, p,
270 						  nbp_vlan_group_rcu(p)))
271 			goto drop;
272 	}
273 
274 	if (unlikely(is_link_local_ether_addr(dest))) {
275 		u16 fwd_mask = p->br->group_fwd_mask_required;
276 
277 		/*
278 		 * See IEEE 802.1D Table 7-10 Reserved addresses
279 		 *
280 		 * Assignment		 		Value
281 		 * Bridge Group Address		01-80-C2-00-00-00
282 		 * (MAC Control) 802.3		01-80-C2-00-00-01
283 		 * (Link Aggregation) 802.3	01-80-C2-00-00-02
284 		 * 802.1X PAE address		01-80-C2-00-00-03
285 		 *
286 		 * 802.1AB LLDP 		01-80-C2-00-00-0E
287 		 *
288 		 * Others reserved for future standardization
289 		 */
290 		switch (dest[5]) {
291 		case 0x00:	/* Bridge Group Address */
292 			/* If STP is turned off,
293 			   then must forward to keep loop detection */
294 			if (p->br->stp_enabled == BR_NO_STP ||
295 			    fwd_mask & (1u << dest[5]))
296 				goto forward;
297 			*pskb = skb;
298 			__br_handle_local_finish(skb);
299 			return RX_HANDLER_PASS;
300 
301 		case 0x01:	/* IEEE MAC (Pause) */
302 			goto drop;
303 
304 		case 0x0E:	/* 802.1AB LLDP */
305 			fwd_mask |= p->br->group_fwd_mask;
306 			if (fwd_mask & (1u << dest[5]))
307 				goto forward;
308 			*pskb = skb;
309 			__br_handle_local_finish(skb);
310 			return RX_HANDLER_PASS;
311 
312 		default:
313 			/* Allow selective forwarding for most other protocols */
314 			fwd_mask |= p->br->group_fwd_mask;
315 			if (fwd_mask & (1u << dest[5]))
316 				goto forward;
317 		}
318 
319 		/* Deliver packet to local host only */
320 		NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, dev_net(skb->dev),
321 			NULL, skb, skb->dev, NULL, br_handle_local_finish);
322 		return RX_HANDLER_CONSUMED;
323 	}
324 
325 forward:
326 	switch (p->state) {
327 	case BR_STATE_FORWARDING:
328 		rhook = rcu_dereference(br_should_route_hook);
329 		if (rhook) {
330 			if ((*rhook)(skb)) {
331 				*pskb = skb;
332 				return RX_HANDLER_PASS;
333 			}
334 			dest = eth_hdr(skb)->h_dest;
335 		}
336 		/* fall through */
337 	case BR_STATE_LEARNING:
338 		if (ether_addr_equal(p->br->dev->dev_addr, dest))
339 			skb->pkt_type = PACKET_HOST;
340 
341 		NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING,
342 			dev_net(skb->dev), NULL, skb, skb->dev, NULL,
343 			br_handle_frame_finish);
344 		break;
345 	default:
346 drop:
347 		kfree_skb(skb);
348 	}
349 	return RX_HANDLER_CONSUMED;
350 }
351