bridge: don't route packets while learning
[linux-2.6.git] / net / bridge / br_input.c
1 /*
2  *      Handle incoming frames
3  *      Linux ethernet bridge
4  *
5  *      Authors:
6  *      Lennert Buytenhek               <buytenh@gnu.org>
7  *
8  *      $Id: br_input.c,v 1.10 2001/12/24 04:50:20 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/etherdevice.h>
19 #include <linux/netfilter_bridge.h>
20 #include "br_private.h"
21
22 /* Bridge group multicast address 802.1d (pg 51). */
23 const u8 br_group_address[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 };
24
25 static void br_pass_frame_up(struct net_bridge *br, struct sk_buff *skb)
26 {
27         struct net_device *indev;
28
29         br->statistics.rx_packets++;
30         br->statistics.rx_bytes += skb->len;
31
32         indev = skb->dev;
33         skb->dev = br->dev;
34
35         NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL,
36                 netif_receive_skb);
37 }
38
39 /* note: already called with rcu_read_lock (preempt_disabled) */
40 int br_handle_frame_finish(struct sk_buff *skb)
41 {
42         const unsigned char *dest = eth_hdr(skb)->h_dest;
43         struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
44         struct net_bridge *br;
45         struct net_bridge_fdb_entry *dst;
46         int passedup = 0;
47
48         if (!p || p->state == BR_STATE_DISABLED)
49                 goto drop;
50
51         /* insert into forwarding database after filtering to avoid spoofing */
52         br = p->br;
53         br_fdb_update(br, p, eth_hdr(skb)->h_source);
54
55         if (p->state == BR_STATE_LEARNING)
56                 goto drop;
57
58         if (br->dev->flags & IFF_PROMISC) {
59                 struct sk_buff *skb2;
60
61                 skb2 = skb_clone(skb, GFP_ATOMIC);
62                 if (skb2 != NULL) {
63                         passedup = 1;
64                         br_pass_frame_up(br, skb2);
65                 }
66         }
67
68         if (is_multicast_ether_addr(dest)) {
69                 br->statistics.multicast++;
70                 br_flood_forward(br, skb, !passedup);
71                 if (!passedup)
72                         br_pass_frame_up(br, skb);
73                 goto out;
74         }
75
76         dst = __br_fdb_get(br, dest);
77         if (dst != NULL && dst->is_local) {
78                 if (!passedup)
79                         br_pass_frame_up(br, skb);
80                 else
81                         kfree_skb(skb);
82                 goto out;
83         }
84
85         if (dst != NULL) {
86                 br_forward(dst->dst, skb);
87                 goto out;
88         }
89
90         br_flood_forward(br, skb, 0);
91
92 out:
93         return 0;
94 drop:
95         kfree_skb(skb);
96         goto out;
97 }
98
99 /* note: already called with rcu_read_lock (preempt_disabled) */
100 static int br_handle_local_finish(struct sk_buff *skb)
101 {
102         struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
103
104         if (p && p->state != BR_STATE_DISABLED)
105                 br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
106
107         return 0;        /* process further */
108 }
109
110 /* Does address match the link local multicast address.
111  * 01:80:c2:00:00:0X
112  */
113 static inline int is_link_local(const unsigned char *dest)
114 {
115         const u16 *a = (const u16 *) dest;
116         static const u16 *const b = (const u16 *const ) br_group_address;
117         static const u16 m = __constant_cpu_to_be16(0xfff0);
118
119         return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0;
120 }
121
122 /*
123  * Called via br_handle_frame_hook.
124  * Return NULL if skb is handled
125  * note: already called with rcu_read_lock (preempt_disabled)
126  */
127 struct sk_buff *br_handle_frame(struct net_bridge_port *p, struct sk_buff *skb)
128 {
129         const unsigned char *dest = eth_hdr(skb)->h_dest;
130
131         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
132                 goto drop;
133
134         if (unlikely(is_link_local(dest))) {
135                 skb->pkt_type = PACKET_HOST;
136
137                 return (NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
138                                 NULL, br_handle_local_finish) == 0) ? skb : NULL;
139         }
140
141         switch (p->state) {
142         case BR_STATE_FORWARDING:
143
144                 if (br_should_route_hook) {
145                         if (br_should_route_hook(&skb))
146                                 return skb;
147                         dest = eth_hdr(skb)->h_dest;
148                 }
149                 /* fall through */
150         case BR_STATE_LEARNING:
151                 if (!compare_ether_addr(p->br->dev->dev_addr, dest))
152                         skb->pkt_type = PACKET_HOST;
153
154                 NF_HOOK(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
155                         br_handle_frame_finish);
156                 break;
157         default:
158 drop:
159                 kfree_skb(skb);
160         }
161         return NULL;
162 }