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 */
21static 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		p->state == BR_STATE_FORWARDING && br_allowed_egress(vg, skb) &&
29		nbp_switchdev_allowed_egress(p, skb) &&
30		!br_skb_isolated(p, skb);
31}
32
33int 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
57drop:
58	kfree_skb(skb);
59	return 0;
60}
61EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);
62
63int 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}
71EXPORT_SYMBOL_GPL(br_forward_finish);
72
73static 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
120static 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 */
144void 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
169out:
170	if (!local_rcv)
171		kfree_skb(skb);
172}
173EXPORT_SYMBOL_GPL(br_forward);
174
175static 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);
193out:
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 */
200void 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
250out:
251	if (!local_rcv)
252		kfree_skb(skb);
253}
254
255#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
256static 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
262	if (!should_deliver(p, skb))
263		return;
264
265	/* Even with hairpin, no soliloquies - prevent breaking IPv6 DAD */
266	if (skb->dev == p->dev && ether_addr_equal(src, addr))
267		return;
268
269	skb = skb_copy(skb, GFP_ATOMIC);
270	if (!skb) {
271		DEV_STATS_INC(dev, tx_dropped);
272		return;
273	}
274
275	if (!is_broadcast_ether_addr(addr))
276		memcpy(eth_hdr(skb)->h_dest, addr, ETH_ALEN);
277
278	__br_forward(p, skb, local_orig);
279}
280
281/* called with rcu_read_lock */
282void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
283			struct sk_buff *skb,
284			struct net_bridge_mcast *brmctx,
285			bool local_rcv, bool local_orig)
286{
287	struct net_bridge_port *prev = NULL;
288	struct net_bridge_port_group *p;
289	bool allow_mode_include = true;
290	struct hlist_node *rp;
291
292	rp = br_multicast_get_first_rport_node(brmctx, skb);
293
294	if (mdst) {
295		p = rcu_dereference(mdst->ports);
296		if (br_multicast_should_handle_mode(brmctx, mdst->addr.proto) &&
297		    br_multicast_is_star_g(&mdst->addr))
298			allow_mode_include = false;
299	} else {
300		p = NULL;
301		br_tc_skb_miss_set(skb, true);
302	}
303
304	while (p || rp) {
305		struct net_bridge_port *port, *lport, *rport;
306
307		lport = p ? p->key.port : NULL;
308		rport = br_multicast_rport_from_node_skb(rp, skb);
309
310		if ((unsigned long)lport > (unsigned long)rport) {
311			port = lport;
312
313			if (port->flags & BR_MULTICAST_TO_UNICAST) {
314				maybe_deliver_addr(lport, skb, p->eth_addr,
315						   local_orig);
316				goto delivered;
317			}
318			if ((!allow_mode_include &&
319			     p->filter_mode == MCAST_INCLUDE) ||
320			    (p->flags & MDB_PG_FLAGS_BLOCKED))
321				goto delivered;
322		} else {
323			port = rport;
324		}
325
326		prev = maybe_deliver(prev, port, skb, local_orig);
327		if (IS_ERR(prev))
328			goto out;
329delivered:
330		if ((unsigned long)lport >= (unsigned long)port)
331			p = rcu_dereference(p->next);
332		if ((unsigned long)rport >= (unsigned long)port)
333			rp = rcu_dereference(hlist_next_rcu(rp));
334	}
335
336	if (!prev)
337		goto out;
338
339	if (local_rcv)
340		deliver_clone(prev, skb, local_orig);
341	else
342		__br_forward(prev, skb, local_orig);
343	return;
344
345out:
346	if (!local_rcv)
347		kfree_skb(skb);
348}
349#endif
350