br_forward.c 6.13 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1
2
3
4
5
6
7
8
9
10
11
12
13
/*
 *	Forwarding decision
 *	Linux ethernet bridge
 *
 *	Authors:
 *	Lennert Buytenhek		<buytenh@gnu.org>
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 */

14
#include <linux/err.h>
15
#include <linux/slab.h>
Linus Torvalds's avatar
Linus Torvalds committed
16
17
#include <linux/kernel.h>
#include <linux/netdevice.h>
18
#include <linux/netpoll.h>
Linus Torvalds's avatar
Linus Torvalds committed
19
#include <linux/skbuff.h>
20
#include <linux/if_vlan.h>
Linus Torvalds's avatar
Linus Torvalds committed
21
22
23
#include <linux/netfilter_bridge.h>
#include "br_private.h"

24
25
static int deliver_clone(const struct net_bridge_port *prev,
			 struct sk_buff *skb,
26
27
28
			 void (*__packet_hook)(const struct net_bridge_port *p,
					       struct sk_buff *skb));

29
/* Don't forward packets to originating port or forwarding diasabled */
30
static inline int should_deliver(const struct net_bridge_port *p,
Linus Torvalds's avatar
Linus Torvalds committed
31
32
				 const struct sk_buff *skb)
{
33
34
	return (((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
		p->state == BR_STATE_FORWARDING);
Linus Torvalds's avatar
Linus Torvalds committed
35
36
}

37
38
39
40
41
static inline unsigned packet_length(const struct sk_buff *skb)
{
	return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0);
}

Linus Torvalds's avatar
Linus Torvalds committed
42
43
int br_dev_queue_push_xmit(struct sk_buff *skb)
{
44
	/* drop mtu oversized packets except gso */
Herbert Xu's avatar
Herbert Xu committed
45
	if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
Linus Torvalds's avatar
Linus Torvalds committed
46
47
		kfree_skb(skb);
	else {
48
		/* ip_fragment doesn't copy the MAC header */
49
50
		if (nf_bridge_maybe_copy_header(skb))
			kfree_skb(skb);
51
		else {
52
			skb_push(skb, ETH_HLEN);
Herbert Xu's avatar
Herbert Xu committed
53
			dev_queue_xmit(skb);
54
		}
Linus Torvalds's avatar
Linus Torvalds committed
55
56
57
58
59
60
61
	}

	return 0;
}

int br_forward_finish(struct sk_buff *skb)
{
62
	return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
63
		       br_dev_queue_push_xmit);
Linus Torvalds's avatar
Linus Torvalds committed
64
65
66
67
68
69

}

static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
{
	skb->dev = to->dev;
Herbert Xu's avatar
Herbert Xu committed
70
71
72
73
74
75
76
77
78
79
80

	if (unlikely(netpoll_tx_running(to->dev))) {
		if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
			kfree_skb(skb);
		else {
			skb_push(skb, ETH_HLEN);
			br_netpoll_send_skb(to, skb);
		}
		return;
	}

81
82
	NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
		br_forward_finish);
Linus Torvalds's avatar
Linus Torvalds committed
83
84
85
86
87
88
}

static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
{
	struct net_device *indev;

Herbert Xu's avatar
Herbert Xu committed
89
90
91
92
93
	if (skb_warn_if_lro(skb)) {
		kfree_skb(skb);
		return;
	}

Linus Torvalds's avatar
Linus Torvalds committed
94
95
	indev = skb->dev;
	skb->dev = to->dev;
96
	skb_forward_csum(skb);
Linus Torvalds's avatar
Linus Torvalds committed
97

98
99
	NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
		br_forward_finish);
Linus Torvalds's avatar
Linus Torvalds committed
100
101
102
103
104
105
106
107
108
109
110
111
112
113
}

/* called with rcu_read_lock */
void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
{
	if (should_deliver(to, skb)) {
		__br_deliver(to, skb);
		return;
	}

	kfree_skb(skb);
}

/* called with rcu_read_lock */
114
void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0)
Linus Torvalds's avatar
Linus Torvalds committed
115
{
Herbert Xu's avatar
Herbert Xu committed
116
	if (should_deliver(to, skb)) {
117
118
119
120
		if (skb0)
			deliver_clone(to, skb, __br_forward);
		else
			__br_forward(to, skb);
Linus Torvalds's avatar
Linus Torvalds committed
121
122
123
		return;
	}

124
125
	if (!skb0)
		kfree_skb(skb);
Linus Torvalds's avatar
Linus Torvalds committed
126
127
}

128
129
static int deliver_clone(const struct net_bridge_port *prev,
			 struct sk_buff *skb,
130
131
132
			 void (*__packet_hook)(const struct net_bridge_port *p,
					       struct sk_buff *skb))
{
133
134
	struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;

135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
	skb = skb_clone(skb, GFP_ATOMIC);
	if (!skb) {
		dev->stats.tx_dropped++;
		return -ENOMEM;
	}

	__packet_hook(prev, skb);
	return 0;
}

static struct net_bridge_port *maybe_deliver(
	struct net_bridge_port *prev, struct net_bridge_port *p,
	struct sk_buff *skb,
	void (*__packet_hook)(const struct net_bridge_port *p,
			      struct sk_buff *skb))
{
	int err;

	if (!should_deliver(p, skb))
		return prev;

	if (!prev)
		goto out;

	err = deliver_clone(prev, skb, __packet_hook);
	if (err)
		return ERR_PTR(err);

out:
	return p;
}

Linus Torvalds's avatar
Linus Torvalds committed
167
/* called under bridge lock */
168
static void br_flood(struct net_bridge *br, struct sk_buff *skb,
169
170
171
		     struct sk_buff *skb0,
		     void (*__packet_hook)(const struct net_bridge_port *p,
					   struct sk_buff *skb))
Linus Torvalds's avatar
Linus Torvalds committed
172
173
174
175
176
177
178
{
	struct net_bridge_port *p;
	struct net_bridge_port *prev;

	prev = NULL;

	list_for_each_entry_rcu(p, &br->port_list, list) {
179
180
181
		prev = maybe_deliver(prev, p, skb, __packet_hook);
		if (IS_ERR(prev))
			goto out;
Linus Torvalds's avatar
Linus Torvalds committed
182
183
	}

184
185
186
	if (!prev)
		goto out;

187
188
189
190
	if (skb0)
		deliver_clone(prev, skb, __packet_hook);
	else
		__packet_hook(prev, skb);
191
	return;
Linus Torvalds's avatar
Linus Torvalds committed
192

193
194
195
out:
	if (!skb0)
		kfree_skb(skb);
Linus Torvalds's avatar
Linus Torvalds committed
196
197
198
199
}


/* called with rcu_read_lock */
200
void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb)
Linus Torvalds's avatar
Linus Torvalds committed
201
{
202
	br_flood(br, skb, NULL, __br_deliver);
Linus Torvalds's avatar
Linus Torvalds committed
203
204
205
}

/* called under bridge lock */
206
207
void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
		      struct sk_buff *skb2)
Linus Torvalds's avatar
Linus Torvalds committed
208
{
209
	br_flood(br, skb, skb2, __br_forward);
Linus Torvalds's avatar
Linus Torvalds committed
210
}
211
212
213
214
215
216
217
218
219
220
221

#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
/* called with rcu_read_lock */
static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
			       struct sk_buff *skb, struct sk_buff *skb0,
			       void (*__packet_hook)(
					const struct net_bridge_port *p,
					struct sk_buff *skb))
{
	struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
	struct net_bridge *br = netdev_priv(dev);
222
	struct net_bridge_port *prev = NULL;
223
224
225
	struct net_bridge_port_group *p;
	struct hlist_node *rp;

stephen hemminger's avatar
stephen hemminger committed
226
	rp = rcu_dereference(br->router_list.first);
227
	p = mdst ? rcu_dereference(mdst->ports) : NULL;
228
	while (p || rp) {
229
230
		struct net_bridge_port *port, *lport, *rport;

231
232
233
234
235
236
237
238
239
240
241
242
		lport = p ? p->port : NULL;
		rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
			     NULL;

		port = (unsigned long)lport > (unsigned long)rport ?
		       lport : rport;

		prev = maybe_deliver(prev, port, skb, __packet_hook);
		if (IS_ERR(prev))
			goto out;

		if ((unsigned long)lport >= (unsigned long)port)
243
			p = rcu_dereference(p->next);
244
		if ((unsigned long)rport >= (unsigned long)port)
stephen hemminger's avatar
stephen hemminger committed
245
			rp = rcu_dereference(rp->next);
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
	}

	if (!prev)
		goto out;

	if (skb0)
		deliver_clone(prev, skb, __packet_hook);
	else
		__packet_hook(prev, skb);
	return;

out:
	if (!skb0)
		kfree_skb(skb);
}

/* called with rcu_read_lock */
void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
			  struct sk_buff *skb)
{
	br_multicast_flood(mdst, skb, NULL, __br_deliver);
}

/* called with rcu_read_lock */
void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
			  struct sk_buff *skb, struct sk_buff *skb2)
{
	br_multicast_flood(mdst, skb, skb2, __br_forward);
}
#endif