d36e700f7a26505b4828a08302b5bfec27b06483
[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  *      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/slab.h>
15 #include <linux/kernel.h>
16 #include <linux/netdevice.h>
17 #include <linux/etherdevice.h>
18 #include <linux/netfilter_bridge.h>
19 #include "br_private.h"
20
21 /* Bridge group multicast address 802.1d (pg 51). */
22 const u8 br_group_address[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 };
23
24 static int br_pass_frame_up(struct sk_buff *skb)
25 {
26         struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
27         struct net_bridge *br = netdev_priv(brdev);
28         struct br_cpu_netstats *brstats = this_cpu_ptr(br->stats);
29
30         brstats->rx_packets++;
31         brstats->rx_bytes += skb->len;
32
33         indev = skb->dev;
34         skb->dev = brdev;
35
36         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL,
37                        netif_receive_skb);
38 }
39
40 /* note: already called with rcu_read_lock (preempt_disabled) */
41 int br_handle_frame_finish(struct sk_buff *skb)
42 {
43         const unsigned char *dest = eth_hdr(skb)->h_dest;
44         struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
45         struct net_bridge *br;
46         struct net_bridge_fdb_entry *dst;
47         struct net_bridge_mdb_entry *mdst;
48         struct sk_buff *skb2;
49
50         if (!p || p->state == BR_STATE_DISABLED)
51                 goto drop;
52
53         /* insert into forwarding database after filtering to avoid spoofing */
54         br = p->br;
55         br_fdb_update(br, p, eth_hdr(skb)->h_source);
56
57         if (is_multicast_ether_addr(dest) &&
58             br_multicast_rcv(br, p, skb))
59                 goto drop;
60
61         if (p->state == BR_STATE_LEARNING)
62                 goto drop;
63
64         BR_INPUT_SKB_CB(skb)->brdev = br->dev;
65
66         /* The packet skb2 goes to the local host (NULL to skip). */
67         skb2 = NULL;
68
69         if (br->dev->flags & IFF_PROMISC)
70                 skb2 = skb;
71
72         dst = NULL;
73
74         if (is_multicast_ether_addr(dest)) {
75                 mdst = br_mdb_get(br, skb);
76                 if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) {
77                         if ((mdst && !hlist_unhashed(&mdst->mglist)) ||
78                             br_multicast_is_router(br))
79                                 skb2 = skb;
80                         br_multicast_forward(mdst, skb, skb2);
81                         skb = NULL;
82                         if (!skb2)
83                                 goto out;
84                 } else
85                         skb2 = skb;
86
87                 br->dev->stats.multicast++;
88         } else if ((dst = __br_fdb_get(br, dest)) && dst->is_local) {
89                 skb2 = skb;
90                 /* Do not forward the packet since it's local. */
91                 skb = NULL;
92         }
93
94         if (skb) {
95                 if (dst)
96                         br_forward(dst->dst, skb, skb2);
97                 else
98                         br_flood_forward(br, skb, skb2);
99         }
100
101         if (skb2)
102                 return br_pass_frame_up(skb2);
103
104 out:
105         return 0;
106 drop:
107         kfree_skb(skb);
108         goto out;
109 }
110
111 /* note: already called with rcu_read_lock (preempt_disabled) */
112 static int br_handle_local_finish(struct sk_buff *skb)
113 {
114         struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
115
116         if (p)
117                 br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
118         return 0;        /* process further */
119 }
120
121 /* Does address match the link local multicast address.
122  * 01:80:c2:00:00:0X
123  */
124 static inline int is_link_local(const unsigned char *dest)
125 {
126         __be16 *a = (__be16 *)dest;
127         static const __be16 *b = (const __be16 *)br_group_address;
128         static const __be16 m = cpu_to_be16(0xfff0);
129
130         return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0;
131 }
132
133 /*
134  * Called via br_handle_frame_hook.
135  * Return NULL if skb is handled
136  * note: already called with rcu_read_lock (preempt_disabled)
137  */
138 struct sk_buff *br_handle_frame(struct net_bridge_port *p, struct sk_buff *skb)
139 {
140         const unsigned char *dest = eth_hdr(skb)->h_dest;
141         int (*rhook)(struct sk_buff *skb);
142
143         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
144                 goto drop;
145
146         skb = skb_share_check(skb, GFP_ATOMIC);
147         if (!skb)
148                 return NULL;
149
150         if (unlikely(is_link_local(dest))) {
151                 /* Pause frames shouldn't be passed up by driver anyway */
152                 if (skb->protocol == htons(ETH_P_PAUSE))
153                         goto drop;
154
155                 /* If STP is turned off, then forward */
156                 if (p->br->stp_enabled == BR_NO_STP && dest[5] == 0)
157                         goto forward;
158
159                 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
160                             NULL, br_handle_local_finish))
161                         return NULL;    /* frame consumed by filter */
162                 else
163                         return skb;     /* continue processing */
164         }
165
166 forward:
167         switch (p->state) {
168         case BR_STATE_FORWARDING:
169                 rhook = rcu_dereference(br_should_route_hook);
170                 if (rhook != NULL) {
171                         if (rhook(skb))
172                                 return skb;
173                         dest = eth_hdr(skb)->h_dest;
174                 }
175                 /* fall through */
176         case BR_STATE_LEARNING:
177                 if (!compare_ether_addr(p->br->dev->dev_addr, dest))
178                         skb->pkt_type = PACKET_HOST;
179
180                 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
181                         br_handle_frame_finish);
182                 break;
183         default:
184 drop:
185                 kfree_skb(skb);
186         }
187         return NULL;
188 }