1/*
2 *	Forwarding decision
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/err.h>
15#include <linux/slab.h>
16#include <linux/kernel.h>
17#include <linux/netdevice.h>
18#include <linux/netpoll.h>
19#include <linux/skbuff.h>
20#include <linux/if_vlan.h>
21#include <linux/netfilter_bridge.h>
22#include "br_private.h"
23
24static int deliver_clone(const struct net_bridge_port *prev,
25			 struct sk_buff *skb,
26			 void (*__packet_hook)(const struct net_bridge_port *p,
27					       struct sk_buff *skb));
28
29/* Don't forward packets to originating port or forwarding disabled */
30static inline int should_deliver(const struct net_bridge_port *p,
31				 const struct sk_buff *skb)
32{
33	struct net_bridge_vlan_group *vg;
34
35	vg = nbp_vlan_group_rcu(p);
36	return ((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
37		br_allowed_egress(vg, skb) && p->state == BR_STATE_FORWARDING;
38}
39
40int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
41{
42	if (!is_skb_forwardable(skb->dev, skb))
43		goto drop;
44
45	skb_push(skb, ETH_HLEN);
46	br_drop_fake_rtable(skb);
47	skb_sender_cpu_clear(skb);
48
49	if (skb->ip_summed == CHECKSUM_PARTIAL &&
50	    (skb->protocol == htons(ETH_P_8021Q) ||
51	     skb->protocol == htons(ETH_P_8021AD))) {
52		int depth;
53
54		if (!__vlan_get_protocol(skb, skb->protocol, &depth))
55			goto drop;
56
57		skb_set_network_header(skb, depth);
58	}
59
60	dev_queue_xmit(skb);
61
62	return 0;
63
64drop:
65	kfree_skb(skb);
66	return 0;
67}
68EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);
69
70int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
71{
72	return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING,
73		       net, sk, skb, NULL, skb->dev,
74		       br_dev_queue_push_xmit);
75
76}
77EXPORT_SYMBOL_GPL(br_forward_finish);
78
79static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
80{
81	struct net_bridge_vlan_group *vg;
82
83	vg = nbp_vlan_group_rcu(to);
84	skb = br_handle_vlan(to->br, vg, skb);
85	if (!skb)
86		return;
87
88	skb->dev = to->dev;
89
90	if (unlikely(netpoll_tx_running(to->br->dev))) {
91		if (!is_skb_forwardable(skb->dev, skb))
92			kfree_skb(skb);
93		else {
94			skb_push(skb, ETH_HLEN);
95			br_netpoll_send_skb(to, skb);
96		}
97		return;
98	}
99
100	NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT,
101		dev_net(skb->dev), NULL, skb,NULL, skb->dev,
102		br_forward_finish);
103}
104
105static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
106{
107	struct net_bridge_vlan_group *vg;
108	struct net_device *indev;
109
110	if (skb_warn_if_lro(skb)) {
111		kfree_skb(skb);
112		return;
113	}
114
115	vg = nbp_vlan_group_rcu(to);
116	skb = br_handle_vlan(to->br, vg, skb);
117	if (!skb)
118		return;
119
120	indev = skb->dev;
121	skb->dev = to->dev;
122	skb_forward_csum(skb);
123
124	NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD,
125		dev_net(indev), NULL, skb, indev, skb->dev,
126		br_forward_finish);
127}
128
129/* called with rcu_read_lock */
130void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
131{
132	if (to && should_deliver(to, skb)) {
133		__br_deliver(to, skb);
134		return;
135	}
136
137	kfree_skb(skb);
138}
139EXPORT_SYMBOL_GPL(br_deliver);
140
141/* called with rcu_read_lock */
142void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0)
143{
144	if (to && should_deliver(to, skb)) {
145		if (skb0)
146			deliver_clone(to, skb, __br_forward);
147		else
148			__br_forward(to, skb);
149		return;
150	}
151
152	if (!skb0)
153		kfree_skb(skb);
154}
155
156static int deliver_clone(const struct net_bridge_port *prev,
157			 struct sk_buff *skb,
158			 void (*__packet_hook)(const struct net_bridge_port *p,
159					       struct sk_buff *skb))
160{
161	struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
162
163	skb = skb_clone(skb, GFP_ATOMIC);
164	if (!skb) {
165		dev->stats.tx_dropped++;
166		return -ENOMEM;
167	}
168
169	__packet_hook(prev, skb);
170	return 0;
171}
172
173static struct net_bridge_port *maybe_deliver(
174	struct net_bridge_port *prev, struct net_bridge_port *p,
175	struct sk_buff *skb,
176	void (*__packet_hook)(const struct net_bridge_port *p,
177			      struct sk_buff *skb))
178{
179	int err;
180
181	if (!should_deliver(p, skb))
182		return prev;
183
184	if (!prev)
185		goto out;
186
187	err = deliver_clone(prev, skb, __packet_hook);
188	if (err)
189		return ERR_PTR(err);
190
191out:
192	return p;
193}
194
195/* called under bridge lock */
196static void br_flood(struct net_bridge *br, struct sk_buff *skb,
197		     struct sk_buff *skb0,
198		     void (*__packet_hook)(const struct net_bridge_port *p,
199					   struct sk_buff *skb),
200		     bool unicast)
201{
202	struct net_bridge_port *p;
203	struct net_bridge_port *prev;
204
205	prev = NULL;
206
207	list_for_each_entry_rcu(p, &br->port_list, list) {
208		/* Do not flood unicast traffic to ports that turn it off */
209		if (unicast && !(p->flags & BR_FLOOD))
210			continue;
211
212		/* Do not flood to ports that enable proxy ARP */
213		if (p->flags & BR_PROXYARP)
214			continue;
215		if ((p->flags & BR_PROXYARP_WIFI) &&
216		    BR_INPUT_SKB_CB(skb)->proxyarp_replied)
217			continue;
218
219		prev = maybe_deliver(prev, p, skb, __packet_hook);
220		if (IS_ERR(prev))
221			goto out;
222	}
223
224	if (!prev)
225		goto out;
226
227	if (skb0)
228		deliver_clone(prev, skb, __packet_hook);
229	else
230		__packet_hook(prev, skb);
231	return;
232
233out:
234	if (!skb0)
235		kfree_skb(skb);
236}
237
238
239/* called with rcu_read_lock */
240void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, bool unicast)
241{
242	br_flood(br, skb, NULL, __br_deliver, unicast);
243}
244
245/* called under bridge lock */
246void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
247		      struct sk_buff *skb2, bool unicast)
248{
249	br_flood(br, skb, skb2, __br_forward, unicast);
250}
251
252#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
253/* called with rcu_read_lock */
254static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
255			       struct sk_buff *skb, struct sk_buff *skb0,
256			       void (*__packet_hook)(
257					const struct net_bridge_port *p,
258					struct sk_buff *skb))
259{
260	struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
261	struct net_bridge *br = netdev_priv(dev);
262	struct net_bridge_port *prev = NULL;
263	struct net_bridge_port_group *p;
264	struct hlist_node *rp;
265
266	rp = rcu_dereference(hlist_first_rcu(&br->router_list));
267	p = mdst ? rcu_dereference(mdst->ports) : NULL;
268	while (p || rp) {
269		struct net_bridge_port *port, *lport, *rport;
270
271		lport = p ? p->port : NULL;
272		rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
273			     NULL;
274
275		port = (unsigned long)lport > (unsigned long)rport ?
276		       lport : rport;
277
278		prev = maybe_deliver(prev, port, skb, __packet_hook);
279		if (IS_ERR(prev))
280			goto out;
281
282		if ((unsigned long)lport >= (unsigned long)port)
283			p = rcu_dereference(p->next);
284		if ((unsigned long)rport >= (unsigned long)port)
285			rp = rcu_dereference(hlist_next_rcu(rp));
286	}
287
288	if (!prev)
289		goto out;
290
291	if (skb0)
292		deliver_clone(prev, skb, __packet_hook);
293	else
294		__packet_hook(prev, skb);
295	return;
296
297out:
298	if (!skb0)
299		kfree_skb(skb);
300}
301
302/* called with rcu_read_lock */
303void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
304			  struct sk_buff *skb)
305{
306	br_multicast_flood(mdst, skb, NULL, __br_deliver);
307}
308
309/* called with rcu_read_lock */
310void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
311			  struct sk_buff *skb, struct sk_buff *skb2)
312{
313	br_multicast_flood(mdst, skb, skb2, __br_forward);
314}
315#endif
316