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