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	    (skb->protocol == htons(ETH_P_8021Q) ||
43	     skb->protocol == htons(ETH_P_8021AD))) {
44		int depth;
45
46		if (!vlan_get_protocol_and_depth(skb, skb->protocol, &depth))
47			goto drop;
48
49		skb_set_network_header(skb, depth);
50	}
51
52	dev_queue_xmit(skb);
53
54	return 0;
55
56drop:
57	kfree_skb(skb);
58	return 0;
59}
60EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);
61
62int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
63{
64	skb->tstamp = 0;
65	return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING,
66		       net, sk, skb, NULL, skb->dev,
67		       br_dev_queue_push_xmit);
68
69}
70EXPORT_SYMBOL_GPL(br_forward_finish);
71
72static void __br_forward(const struct net_bridge_port *to,
73			 struct sk_buff *skb, bool local_orig)
74{
75	struct net_bridge_vlan_group *vg;
76	struct net_device *indev;
77	struct net *net;
78	int br_hook;
79
80	vg = nbp_vlan_group_rcu(to);
81	skb = br_handle_vlan(to->br, to, vg, skb);
82	if (!skb)
83		return;
84
85	indev = skb->dev;
86	skb->dev = to->dev;
87	if (!local_orig) {
88		if (skb_warn_if_lro(skb)) {
89			kfree_skb(skb);
90			return;
91		}
92		br_hook = NF_BR_FORWARD;
93		skb_forward_csum(skb);
94		net = dev_net(indev);
95	} else {
96		if (unlikely(netpoll_tx_running(to->br->dev))) {
97			skb_push(skb, ETH_HLEN);
98			if (!is_skb_forwardable(skb->dev, skb))
99				kfree_skb(skb);
100			else
101				br_netpoll_send_skb(to, skb);
102			return;
103		}
104		br_hook = NF_BR_LOCAL_OUT;
105		net = dev_net(skb->dev);
106		indev = NULL;
107	}
108
109	NF_HOOK(NFPROTO_BRIDGE, br_hook,
110		net, NULL, skb, indev, skb->dev,
111		br_forward_finish);
112}
113
114static int deliver_clone(const struct net_bridge_port *prev,
115			 struct sk_buff *skb, bool local_orig)
116{
117	struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
118
119	skb = skb_clone(skb, GFP_ATOMIC);
120	if (!skb) {
121		DEV_STATS_INC(dev, tx_dropped);
122		return -ENOMEM;
123	}
124
125	__br_forward(prev, skb, local_orig);
126	return 0;
127}
128
129/**
130 * br_forward - forward a packet to a specific port
131 * @to: destination port
132 * @skb: packet being forwarded
133 * @local_rcv: packet will be received locally after forwarding
134 * @local_orig: packet is locally originated
135 *
136 * Should be called with rcu_read_lock.
137 */
138void br_forward(const struct net_bridge_port *to,
139		struct sk_buff *skb, bool local_rcv, bool local_orig)
140{
141	if (unlikely(!to))
142		goto out;
143
144	/* redirect to backup link if the destination port is down */
145	if (rcu_access_pointer(to->backup_port) && !netif_carrier_ok(to->dev)) {
146		struct net_bridge_port *backup_port;
147
148		backup_port = rcu_dereference(to->backup_port);
149		if (unlikely(!backup_port))
150			goto out;
151		to = backup_port;
152	}
153
154	if (should_deliver(to, skb)) {
155		if (local_rcv)
156			deliver_clone(to, skb, local_orig);
157		else
158			__br_forward(to, skb, local_orig);
159		return;
160	}
161
162out:
163	if (!local_rcv)
164		kfree_skb(skb);
165}
166EXPORT_SYMBOL_GPL(br_forward);
167
168static struct net_bridge_port *maybe_deliver(
169	struct net_bridge_port *prev, struct net_bridge_port *p,
170	struct sk_buff *skb, bool local_orig)
171{
172	u8 igmp_type = br_multicast_igmp_type(skb);
173	int err;
174
175	if (!should_deliver(p, skb))
176		return prev;
177
178	if (!prev)
179		goto out;
180
181	err = deliver_clone(prev, skb, local_orig);
182	if (err)
183		return ERR_PTR(err);
184out:
185	br_multicast_count(p->br, p, skb, igmp_type, BR_MCAST_DIR_TX);
186
187	return p;
188}
189
190/* called under rcu_read_lock */
191void br_flood(struct net_bridge *br, struct sk_buff *skb,
192	      enum br_pkt_type pkt_type, bool local_rcv, bool local_orig)
193{
194	struct net_bridge_port *prev = NULL;
195	struct net_bridge_port *p;
196
197	list_for_each_entry_rcu(p, &br->port_list, list) {
198		/* Do not flood unicast traffic to ports that turn it off, nor
199		 * other traffic if flood off, except for traffic we originate
200		 */
201		switch (pkt_type) {
202		case BR_PKT_UNICAST:
203			if (!(p->flags & BR_FLOOD))
204				continue;
205			break;
206		case BR_PKT_MULTICAST:
207			if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev)
208				continue;
209			break;
210		case BR_PKT_BROADCAST:
211			if (!(p->flags & BR_BCAST_FLOOD) && skb->dev != br->dev)
212				continue;
213			break;
214		}
215
216		/* Do not flood to ports that enable proxy ARP */
217		if (p->flags & BR_PROXYARP)
218			continue;
219		if ((p->flags & (BR_PROXYARP_WIFI | BR_NEIGH_SUPPRESS)) &&
220		    BR_INPUT_SKB_CB(skb)->proxyarp_replied)
221			continue;
222
223		prev = maybe_deliver(prev, p, skb, local_orig);
224		if (IS_ERR(prev))
225			goto out;
226	}
227
228	if (!prev)
229		goto out;
230
231	if (local_rcv)
232		deliver_clone(prev, skb, local_orig);
233	else
234		__br_forward(prev, skb, local_orig);
235	return;
236
237out:
238	if (!local_rcv)
239		kfree_skb(skb);
240}
241
242#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
243static void maybe_deliver_addr(struct net_bridge_port *p, struct sk_buff *skb,
244			       const unsigned char *addr, bool local_orig)
245{
246	struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
247	const unsigned char *src = eth_hdr(skb)->h_source;
248
249	if (!should_deliver(p, skb))
250		return;
251
252	/* Even with hairpin, no soliloquies - prevent breaking IPv6 DAD */
253	if (skb->dev == p->dev && ether_addr_equal(src, addr))
254		return;
255
256	skb = skb_copy(skb, GFP_ATOMIC);
257	if (!skb) {
258		DEV_STATS_INC(dev, tx_dropped);
259		return;
260	}
261
262	if (!is_broadcast_ether_addr(addr))
263		memcpy(eth_hdr(skb)->h_dest, addr, ETH_ALEN);
264
265	__br_forward(p, skb, local_orig);
266}
267
268/* called with rcu_read_lock */
269void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
270			struct sk_buff *skb,
271			bool local_rcv, bool local_orig)
272{
273	struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
274	struct net_bridge *br = netdev_priv(dev);
275	struct net_bridge_port *prev = NULL;
276	struct net_bridge_port_group *p;
277	bool allow_mode_include = true;
278	struct hlist_node *rp;
279
280	rp = rcu_dereference(hlist_first_rcu(&br->router_list));
281	if (mdst) {
282		p = rcu_dereference(mdst->ports);
283		if (br_multicast_should_handle_mode(br, mdst->addr.proto) &&
284		    br_multicast_is_star_g(&mdst->addr))
285			allow_mode_include = false;
286	} else {
287		p = NULL;
288	}
289
290	while (p || rp) {
291		struct net_bridge_port *port, *lport, *rport;
292
293		lport = p ? p->key.port : NULL;
294		rport = hlist_entry_safe(rp, struct net_bridge_port, rlist);
295
296		if ((unsigned long)lport > (unsigned long)rport) {
297			port = lport;
298
299			if (port->flags & BR_MULTICAST_TO_UNICAST) {
300				maybe_deliver_addr(lport, skb, p->eth_addr,
301						   local_orig);
302				goto delivered;
303			}
304			if ((!allow_mode_include &&
305			     p->filter_mode == MCAST_INCLUDE) ||
306			    (p->flags & MDB_PG_FLAGS_BLOCKED))
307				goto delivered;
308		} else {
309			port = rport;
310		}
311
312		prev = maybe_deliver(prev, port, skb, local_orig);
313		if (IS_ERR(prev))
314			goto out;
315delivered:
316		if ((unsigned long)lport >= (unsigned long)port)
317			p = rcu_dereference(p->next);
318		if ((unsigned long)rport >= (unsigned long)port)
319			rp = rcu_dereference(hlist_next_rcu(rp));
320	}
321
322	if (!prev)
323		goto out;
324
325	if (local_rcv)
326		deliver_clone(prev, skb, local_orig);
327	else
328		__br_forward(prev, skb, local_orig);
329	return;
330
331out:
332	if (!local_rcv)
333		kfree_skb(skb);
334}
335#endif
336