Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6
[sfrench/cifs-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         u64_stats_update_begin(&brstats->syncp);
31         brstats->rx_packets++;
32         brstats->rx_bytes += skb->len;
33         u64_stats_update_end(&brstats->syncp);
34
35         indev = skb->dev;
36         skb->dev = brdev;
37
38         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL,
39                        netif_receive_skb);
40 }
41
42 /* note: already called with rcu_read_lock */
43 int br_handle_frame_finish(struct sk_buff *skb)
44 {
45         const unsigned char *dest = eth_hdr(skb)->h_dest;
46         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
47         struct net_bridge *br;
48         struct net_bridge_fdb_entry *dst;
49         struct net_bridge_mdb_entry *mdst;
50         struct sk_buff *skb2;
51
52         if (!p || p->state == BR_STATE_DISABLED)
53                 goto drop;
54
55         /* insert into forwarding database after filtering to avoid spoofing */
56         br = p->br;
57         br_fdb_update(br, p, eth_hdr(skb)->h_source);
58
59         if (is_multicast_ether_addr(dest) &&
60             br_multicast_rcv(br, p, skb))
61                 goto drop;
62
63         if (p->state == BR_STATE_LEARNING)
64                 goto drop;
65
66         BR_INPUT_SKB_CB(skb)->brdev = br->dev;
67
68         /* The packet skb2 goes to the local host (NULL to skip). */
69         skb2 = NULL;
70
71         if (br->dev->flags & IFF_PROMISC)
72                 skb2 = skb;
73
74         dst = NULL;
75
76         if (is_multicast_ether_addr(dest)) {
77                 mdst = br_mdb_get(br, skb);
78                 if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) {
79                         if ((mdst && !hlist_unhashed(&mdst->mglist)) ||
80                             br_multicast_is_router(br))
81                                 skb2 = skb;
82                         br_multicast_forward(mdst, skb, skb2);
83                         skb = NULL;
84                         if (!skb2)
85                                 goto out;
86                 } else
87                         skb2 = skb;
88
89                 br->dev->stats.multicast++;
90         } else if ((dst = __br_fdb_get(br, dest)) && dst->is_local) {
91                 skb2 = skb;
92                 /* Do not forward the packet since it's local. */
93                 skb = NULL;
94         }
95
96         if (skb) {
97                 if (dst)
98                         br_forward(dst->dst, skb, skb2);
99                 else
100                         br_flood_forward(br, skb, skb2);
101         }
102
103         if (skb2)
104                 return br_pass_frame_up(skb2);
105
106 out:
107         return 0;
108 drop:
109         kfree_skb(skb);
110         goto out;
111 }
112
113 /* note: already called with rcu_read_lock */
114 static int br_handle_local_finish(struct sk_buff *skb)
115 {
116         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
117
118         br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
119         return 0;        /* process further */
120 }
121
122 /* Does address match the link local multicast address.
123  * 01:80:c2:00:00:0X
124  */
125 static inline int is_link_local(const unsigned char *dest)
126 {
127         __be16 *a = (__be16 *)dest;
128         static const __be16 *b = (const __be16 *)br_group_address;
129         static const __be16 m = cpu_to_be16(0xfff0);
130
131         return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0;
132 }
133
134 /*
135  * Return NULL if skb is handled
136  * note: already called with rcu_read_lock
137  */
138 struct sk_buff *br_handle_frame(struct sk_buff *skb)
139 {
140         struct net_bridge_port *p;
141         const unsigned char *dest = eth_hdr(skb)->h_dest;
142         int (*rhook)(struct sk_buff *skb);
143
144         if (skb->pkt_type == PACKET_LOOPBACK)
145                 return skb;
146
147         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
148                 goto drop;
149
150         skb = skb_share_check(skb, GFP_ATOMIC);
151         if (!skb)
152                 return NULL;
153
154         p = br_port_get_rcu(skb->dev);
155
156         if (unlikely(is_link_local(dest))) {
157                 /* Pause frames shouldn't be passed up by driver anyway */
158                 if (skb->protocol == htons(ETH_P_PAUSE))
159                         goto drop;
160
161                 /* If STP is turned off, then forward */
162                 if (p->br->stp_enabled == BR_NO_STP && dest[5] == 0)
163                         goto forward;
164
165                 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
166                             NULL, br_handle_local_finish))
167                         return NULL;    /* frame consumed by filter */
168                 else
169                         return skb;     /* continue processing */
170         }
171
172 forward:
173         switch (p->state) {
174         case BR_STATE_FORWARDING:
175                 rhook = rcu_dereference(br_should_route_hook);
176                 if (rhook != NULL) {
177                         if (rhook(skb))
178                                 return skb;
179                         dest = eth_hdr(skb)->h_dest;
180                 }
181                 /* fall through */
182         case BR_STATE_LEARNING:
183                 if (!compare_ether_addr(p->br->dev->dev_addr, dest))
184                         skb->pkt_type = PACKET_HOST;
185
186                 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
187                         br_handle_frame_finish);
188                 break;
189         default:
190 drop:
191                 kfree_skb(skb);
192         }
193         return NULL;
194 }