xref: /linux/net/bridge/br_forward.c (revision a1ff5a7d78a036d6c2178ee5acd6ba4946243800)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *	Forwarding decision
4  *	Linux ethernet bridge
5  *
6  *	Authors:
7  *	Lennert Buytenhek		<buytenh@gnu.org>
8  */
9 
10 #include <linux/err.h>
11 #include <linux/slab.h>
12 #include <linux/kernel.h>
13 #include <linux/netdevice.h>
14 #include <linux/netpoll.h>
15 #include <linux/skbuff.h>
16 #include <linux/if_vlan.h>
17 #include <linux/netfilter_bridge.h>
18 #include "br_private.h"
19 
20 /* Don't forward packets to originating port or forwarding disabled */
should_deliver(const struct net_bridge_port * p,const struct sk_buff * skb)21 static inline int should_deliver(const struct net_bridge_port *p,
22 				 const struct sk_buff *skb)
23 {
24 	struct net_bridge_vlan_group *vg;
25 
26 	vg = nbp_vlan_group_rcu(p);
27 	return ((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
28 		(br_mst_is_enabled(p->br) || p->state == BR_STATE_FORWARDING) &&
29 		br_allowed_egress(vg, skb) && nbp_switchdev_allowed_egress(p, skb) &&
30 		!br_skb_isolated(p, skb);
31 }
32 
br_dev_queue_push_xmit(struct net * net,struct sock * sk,struct sk_buff * skb)33 int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
34 {
35 	skb_push(skb, ETH_HLEN);
36 	if (!is_skb_forwardable(skb->dev, skb))
37 		goto drop;
38 
39 	br_drop_fake_rtable(skb);
40 
41 	if (skb->ip_summed == CHECKSUM_PARTIAL &&
42 	    eth_type_vlan(skb->protocol)) {
43 		int depth;
44 
45 		if (!vlan_get_protocol_and_depth(skb, skb->protocol, &depth))
46 			goto drop;
47 
48 		skb_set_network_header(skb, depth);
49 	}
50 
51 	br_switchdev_frame_set_offload_fwd_mark(skb);
52 
53 	dev_queue_xmit(skb);
54 
55 	return 0;
56 
57 drop:
58 	kfree_skb(skb);
59 	return 0;
60 }
61 EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);
62 
br_forward_finish(struct net * net,struct sock * sk,struct sk_buff * skb)63 int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
64 {
65 	skb_clear_tstamp(skb);
66 	return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING,
67 		       net, sk, skb, NULL, skb->dev,
68 		       br_dev_queue_push_xmit);
69 
70 }
71 EXPORT_SYMBOL_GPL(br_forward_finish);
72 
__br_forward(const struct net_bridge_port * to,struct sk_buff * skb,bool local_orig)73 static void __br_forward(const struct net_bridge_port *to,
74 			 struct sk_buff *skb, bool local_orig)
75 {
76 	struct net_bridge_vlan_group *vg;
77 	struct net_device *indev;
78 	struct net *net;
79 	int br_hook;
80 
81 	/* Mark the skb for forwarding offload early so that br_handle_vlan()
82 	 * can know whether to pop the VLAN header on egress or keep it.
83 	 */
84 	nbp_switchdev_frame_mark_tx_fwd_offload(to, skb);
85 
86 	vg = nbp_vlan_group_rcu(to);
87 	skb = br_handle_vlan(to->br, to, vg, skb);
88 	if (!skb)
89 		return;
90 
91 	indev = skb->dev;
92 	skb->dev = to->dev;
93 	if (!local_orig) {
94 		if (skb_warn_if_lro(skb)) {
95 			kfree_skb(skb);
96 			return;
97 		}
98 		br_hook = NF_BR_FORWARD;
99 		skb_forward_csum(skb);
100 		net = dev_net(indev);
101 	} else {
102 		if (unlikely(netpoll_tx_running(to->br->dev))) {
103 			skb_push(skb, ETH_HLEN);
104 			if (!is_skb_forwardable(skb->dev, skb))
105 				kfree_skb(skb);
106 			else
107 				br_netpoll_send_skb(to, skb);
108 			return;
109 		}
110 		br_hook = NF_BR_LOCAL_OUT;
111 		net = dev_net(skb->dev);
112 		indev = NULL;
113 	}
114 
115 	NF_HOOK(NFPROTO_BRIDGE, br_hook,
116 		net, NULL, skb, indev, skb->dev,
117 		br_forward_finish);
118 }
119 
deliver_clone(const struct net_bridge_port * prev,struct sk_buff * skb,bool local_orig)120 static int deliver_clone(const struct net_bridge_port *prev,
121 			 struct sk_buff *skb, bool local_orig)
122 {
123 	struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
124 
125 	skb = skb_clone(skb, GFP_ATOMIC);
126 	if (!skb) {
127 		DEV_STATS_INC(dev, tx_dropped);
128 		return -ENOMEM;
129 	}
130 
131 	__br_forward(prev, skb, local_orig);
132 	return 0;
133 }
134 
135 /**
136  * br_forward - forward a packet to a specific port
137  * @to: destination port
138  * @skb: packet being forwarded
139  * @local_rcv: packet will be received locally after forwarding
140  * @local_orig: packet is locally originated
141  *
142  * Should be called with rcu_read_lock.
143  */
br_forward(const struct net_bridge_port * to,struct sk_buff * skb,bool local_rcv,bool local_orig)144 void br_forward(const struct net_bridge_port *to,
145 		struct sk_buff *skb, bool local_rcv, bool local_orig)
146 {
147 	if (unlikely(!to))
148 		goto out;
149 
150 	/* redirect to backup link if the destination port is down */
151 	if (rcu_access_pointer(to->backup_port) && !netif_carrier_ok(to->dev)) {
152 		struct net_bridge_port *backup_port;
153 
154 		backup_port = rcu_dereference(to->backup_port);
155 		if (unlikely(!backup_port))
156 			goto out;
157 		BR_INPUT_SKB_CB(skb)->backup_nhid = READ_ONCE(to->backup_nhid);
158 		to = backup_port;
159 	}
160 
161 	if (should_deliver(to, skb)) {
162 		if (local_rcv)
163 			deliver_clone(to, skb, local_orig);
164 		else
165 			__br_forward(to, skb, local_orig);
166 		return;
167 	}
168 
169 out:
170 	if (!local_rcv)
171 		kfree_skb(skb);
172 }
173 EXPORT_SYMBOL_GPL(br_forward);
174 
maybe_deliver(struct net_bridge_port * prev,struct net_bridge_port * p,struct sk_buff * skb,bool local_orig)175 static struct net_bridge_port *maybe_deliver(
176 	struct net_bridge_port *prev, struct net_bridge_port *p,
177 	struct sk_buff *skb, bool local_orig)
178 {
179 	u8 igmp_type = br_multicast_igmp_type(skb);
180 	int err;
181 
182 	if (!should_deliver(p, skb))
183 		return prev;
184 
185 	nbp_switchdev_frame_mark_tx_fwd_to_hwdom(p, skb);
186 
187 	if (!prev)
188 		goto out;
189 
190 	err = deliver_clone(prev, skb, local_orig);
191 	if (err)
192 		return ERR_PTR(err);
193 out:
194 	br_multicast_count(p->br, p, skb, igmp_type, BR_MCAST_DIR_TX);
195 
196 	return p;
197 }
198 
199 /* called under rcu_read_lock */
br_flood(struct net_bridge * br,struct sk_buff * skb,enum br_pkt_type pkt_type,bool local_rcv,bool local_orig,u16 vid)200 void br_flood(struct net_bridge *br, struct sk_buff *skb,
201 	      enum br_pkt_type pkt_type, bool local_rcv, bool local_orig,
202 	      u16 vid)
203 {
204 	struct net_bridge_port *prev = NULL;
205 	struct net_bridge_port *p;
206 
207 	br_tc_skb_miss_set(skb, pkt_type != BR_PKT_BROADCAST);
208 
209 	list_for_each_entry_rcu(p, &br->port_list, list) {
210 		/* Do not flood unicast traffic to ports that turn it off, nor
211 		 * other traffic if flood off, except for traffic we originate
212 		 */
213 		switch (pkt_type) {
214 		case BR_PKT_UNICAST:
215 			if (!(p->flags & BR_FLOOD))
216 				continue;
217 			break;
218 		case BR_PKT_MULTICAST:
219 			if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev)
220 				continue;
221 			break;
222 		case BR_PKT_BROADCAST:
223 			if (!(p->flags & BR_BCAST_FLOOD) && skb->dev != br->dev)
224 				continue;
225 			break;
226 		}
227 
228 		/* Do not flood to ports that enable proxy ARP */
229 		if (p->flags & BR_PROXYARP)
230 			continue;
231 		if (BR_INPUT_SKB_CB(skb)->proxyarp_replied &&
232 		    ((p->flags & BR_PROXYARP_WIFI) ||
233 		     br_is_neigh_suppress_enabled(p, vid)))
234 			continue;
235 
236 		prev = maybe_deliver(prev, p, skb, local_orig);
237 		if (IS_ERR(prev))
238 			goto out;
239 	}
240 
241 	if (!prev)
242 		goto out;
243 
244 	if (local_rcv)
245 		deliver_clone(prev, skb, local_orig);
246 	else
247 		__br_forward(prev, skb, local_orig);
248 	return;
249 
250 out:
251 	if (!local_rcv)
252 		kfree_skb(skb);
253 }
254 
255 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
maybe_deliver_addr(struct net_bridge_port * p,struct sk_buff * skb,const unsigned char * addr,bool local_orig)256 static void maybe_deliver_addr(struct net_bridge_port *p, struct sk_buff *skb,
257 			       const unsigned char *addr, bool local_orig)
258 {
259 	struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
260 	const unsigned char *src = eth_hdr(skb)->h_source;
261 	struct sk_buff *nskb;
262 
263 	if (!should_deliver(p, skb))
264 		return;
265 
266 	/* Even with hairpin, no soliloquies - prevent breaking IPv6 DAD */
267 	if (skb->dev == p->dev && ether_addr_equal(src, addr))
268 		return;
269 
270 	__skb_push(skb, ETH_HLEN);
271 	nskb = pskb_copy(skb, GFP_ATOMIC);
272 	__skb_pull(skb, ETH_HLEN);
273 	if (!nskb) {
274 		DEV_STATS_INC(dev, tx_dropped);
275 		return;
276 	}
277 
278 	skb = nskb;
279 	__skb_pull(skb, ETH_HLEN);
280 	if (!is_broadcast_ether_addr(addr))
281 		memcpy(eth_hdr(skb)->h_dest, addr, ETH_ALEN);
282 
283 	__br_forward(p, skb, local_orig);
284 }
285 
286 /* called with rcu_read_lock */
br_multicast_flood(struct net_bridge_mdb_entry * mdst,struct sk_buff * skb,struct net_bridge_mcast * brmctx,bool local_rcv,bool local_orig)287 void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
288 			struct sk_buff *skb,
289 			struct net_bridge_mcast *brmctx,
290 			bool local_rcv, bool local_orig)
291 {
292 	struct net_bridge_port *prev = NULL;
293 	struct net_bridge_port_group *p;
294 	bool allow_mode_include = true;
295 	struct hlist_node *rp;
296 
297 	rp = br_multicast_get_first_rport_node(brmctx, skb);
298 
299 	if (mdst) {
300 		p = rcu_dereference(mdst->ports);
301 		if (br_multicast_should_handle_mode(brmctx, mdst->addr.proto) &&
302 		    br_multicast_is_star_g(&mdst->addr))
303 			allow_mode_include = false;
304 	} else {
305 		p = NULL;
306 		br_tc_skb_miss_set(skb, true);
307 	}
308 
309 	while (p || rp) {
310 		struct net_bridge_port *port, *lport, *rport;
311 
312 		lport = p ? p->key.port : NULL;
313 		rport = br_multicast_rport_from_node_skb(rp, skb);
314 
315 		if ((unsigned long)lport > (unsigned long)rport) {
316 			port = lport;
317 
318 			if (port->flags & BR_MULTICAST_TO_UNICAST) {
319 				maybe_deliver_addr(lport, skb, p->eth_addr,
320 						   local_orig);
321 				goto delivered;
322 			}
323 			if ((!allow_mode_include &&
324 			     p->filter_mode == MCAST_INCLUDE) ||
325 			    (p->flags & MDB_PG_FLAGS_BLOCKED))
326 				goto delivered;
327 		} else {
328 			port = rport;
329 		}
330 
331 		prev = maybe_deliver(prev, port, skb, local_orig);
332 		if (IS_ERR(prev))
333 			goto out;
334 delivered:
335 		if ((unsigned long)lport >= (unsigned long)port)
336 			p = rcu_dereference(p->next);
337 		if ((unsigned long)rport >= (unsigned long)port)
338 			rp = rcu_dereference(hlist_next_rcu(rp));
339 	}
340 
341 	if (!prev)
342 		goto out;
343 
344 	if (local_rcv)
345 		deliver_clone(prev, skb, local_orig);
346 	else
347 		__br_forward(prev, skb, local_orig);
348 	return;
349 
350 out:
351 	if (!local_rcv)
352 		kfree_skb(skb);
353 }
354 #endif
355