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1/*
2 * Forwarding decision
3 * Linux ethernet bridge
4 *
5 * Authors:
6 * Lennert Buytenhek <buytenh@gnu.org>
7 *
8 * $Id: br_forward.c,v 1.4 2001/08/14 22:05:57 davem Exp $
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version
13 * 2 of the License, or (at your option) any later version.
14 */
15
16#include <linux/kernel.h>
17#include <linux/netdevice.h>
18#include <linux/skbuff.h>
19#include <linux/if_vlan.h>
20#include <linux/netfilter_bridge.h>
21#include "br_private.h"
22
23/* Don't forward packets to originating port or forwarding diasabled */
24static inline int should_deliver(const struct net_bridge_port *p,
25 const struct sk_buff *skb)
26{
27 return (skb->dev != p->dev && p->state == BR_STATE_FORWARDING);
28}
29
30static inline unsigned packet_length(const struct sk_buff *skb)
31{
32 return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0);
33}
34
35int br_dev_queue_push_xmit(struct sk_buff *skb)
36{
37 /* drop mtu oversized packets except gso */
38 if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
39 kfree_skb(skb);
40 else {
41 /* ip_refrag calls ip_fragment, doesn't copy the MAC header. */
42 if (nf_bridge_maybe_copy_header(skb))
43 kfree_skb(skb);
44 else {
45 skb_push(skb, ETH_HLEN);
46
47 dev_queue_xmit(skb);
48 }
49 }
50
51 return 0;
52}
53
54int br_forward_finish(struct sk_buff *skb)
55{
56 return NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
57 br_dev_queue_push_xmit);
58
59}
60
61static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
62{
63 skb->dev = to->dev;
64 NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
65 br_forward_finish);
66}
67
68static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
69{
70 struct net_device *indev;
71
72 indev = skb->dev;
73 skb->dev = to->dev;
74 skb_forward_csum(skb);
75
76 NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
77 br_forward_finish);
78}
79
80/* called with rcu_read_lock */
81void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
82{
83 if (should_deliver(to, skb)) {
84 __br_deliver(to, skb);
85 return;
86 }
87
88 kfree_skb(skb);
89}
90
91/* called with rcu_read_lock */
92void br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
93{
94 if (should_deliver(to, skb)) {
95 __br_forward(to, skb);
96 return;
97 }
98
99 kfree_skb(skb);
100}
101
102/* called under bridge lock */
103static void br_flood(struct net_bridge *br, struct sk_buff *skb,
104 void (*__packet_hook)(const struct net_bridge_port *p,
105 struct sk_buff *skb))
106{
107 struct net_bridge_port *p;
108 struct net_bridge_port *prev;
109
110 prev = NULL;
111
112 list_for_each_entry_rcu(p, &br->port_list, list) {
113 if (should_deliver(p, skb)) {
114 if (prev != NULL) {
115 struct sk_buff *skb2;
116
117 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
118 br->statistics.tx_dropped++;
119 kfree_skb(skb);
120 return;
121 }
122
123 __packet_hook(prev, skb2);
124 }
125
126 prev = p;
127 }
128 }
129
130 if (prev != NULL) {
131 __packet_hook(prev, skb);
132 return;
133 }
134
135 kfree_skb(skb);
136}
137
138
139/* called with rcu_read_lock */
140void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb)
141{
142 br_flood(br, skb, __br_deliver);
143}
144
145/* called under bridge lock */
146void br_flood_forward(struct net_bridge *br, struct sk_buff *skb)
147{
148 br_flood(br, skb, __br_forward);
149}