net: introduce rx_handler results and logic around that
[pandora-kernel.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 /* Hook for brouter */
25 br_should_route_hook_t __rcu *br_should_route_hook __read_mostly;
26 EXPORT_SYMBOL(br_should_route_hook);
27
28 static int br_pass_frame_up(struct sk_buff *skb)
29 {
30         struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
31         struct net_bridge *br = netdev_priv(brdev);
32         struct br_cpu_netstats *brstats = this_cpu_ptr(br->stats);
33
34         u64_stats_update_begin(&brstats->syncp);
35         brstats->rx_packets++;
36         brstats->rx_bytes += skb->len;
37         u64_stats_update_end(&brstats->syncp);
38
39         indev = skb->dev;
40         skb->dev = brdev;
41
42         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL,
43                        netif_receive_skb);
44 }
45
46 /* note: already called with rcu_read_lock */
47 int br_handle_frame_finish(struct sk_buff *skb)
48 {
49         const unsigned char *dest = eth_hdr(skb)->h_dest;
50         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
51         struct net_bridge *br;
52         struct net_bridge_fdb_entry *dst;
53         struct net_bridge_mdb_entry *mdst;
54         struct sk_buff *skb2;
55
56         if (!p || p->state == BR_STATE_DISABLED)
57                 goto drop;
58
59         /* insert into forwarding database after filtering to avoid spoofing */
60         br = p->br;
61         br_fdb_update(br, p, eth_hdr(skb)->h_source);
62
63         if (is_multicast_ether_addr(dest) &&
64             br_multicast_rcv(br, p, skb))
65                 goto drop;
66
67         if (p->state == BR_STATE_LEARNING)
68                 goto drop;
69
70         BR_INPUT_SKB_CB(skb)->brdev = br->dev;
71
72         /* The packet skb2 goes to the local host (NULL to skip). */
73         skb2 = NULL;
74
75         if (br->dev->flags & IFF_PROMISC)
76                 skb2 = skb;
77
78         dst = NULL;
79
80         if (is_multicast_ether_addr(dest)) {
81                 mdst = br_mdb_get(br, skb);
82                 if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) {
83                         if ((mdst && mdst->mglist) ||
84                             br_multicast_is_router(br))
85                                 skb2 = skb;
86                         br_multicast_forward(mdst, skb, skb2);
87                         skb = NULL;
88                         if (!skb2)
89                                 goto out;
90                 } else
91                         skb2 = skb;
92
93                 br->dev->stats.multicast++;
94         } else if ((dst = __br_fdb_get(br, dest)) && dst->is_local) {
95                 skb2 = skb;
96                 /* Do not forward the packet since it's local. */
97                 skb = NULL;
98         }
99
100         if (skb) {
101                 if (dst)
102                         br_forward(dst->dst, skb, skb2);
103                 else
104                         br_flood_forward(br, skb, skb2);
105         }
106
107         if (skb2)
108                 return br_pass_frame_up(skb2);
109
110 out:
111         return 0;
112 drop:
113         kfree_skb(skb);
114         goto out;
115 }
116
117 /* note: already called with rcu_read_lock */
118 static int br_handle_local_finish(struct sk_buff *skb)
119 {
120         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
121
122         br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
123         return 0;        /* process further */
124 }
125
126 /* Does address match the link local multicast address.
127  * 01:80:c2:00:00:0X
128  */
129 static inline int is_link_local(const unsigned char *dest)
130 {
131         __be16 *a = (__be16 *)dest;
132         static const __be16 *b = (const __be16 *)br_group_address;
133         static const __be16 m = cpu_to_be16(0xfff0);
134
135         return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0;
136 }
137
138 /*
139  * Return NULL if skb is handled
140  * note: already called with rcu_read_lock
141  */
142 rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
143 {
144         struct net_bridge_port *p;
145         struct sk_buff *skb = *pskb;
146         const unsigned char *dest = eth_hdr(skb)->h_dest;
147         br_should_route_hook_t *rhook;
148
149         if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
150                 return RX_HANDLER_PASS;
151
152         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
153                 goto drop;
154
155         skb = skb_share_check(skb, GFP_ATOMIC);
156         if (!skb)
157                 return RX_HANDLER_CONSUMED;
158
159         p = br_port_get_rcu(skb->dev);
160
161         if (unlikely(is_link_local(dest))) {
162                 /* Pause frames shouldn't be passed up by driver anyway */
163                 if (skb->protocol == htons(ETH_P_PAUSE))
164                         goto drop;
165
166                 /* If STP is turned off, then forward */
167                 if (p->br->stp_enabled == BR_NO_STP)
168                         goto forward;
169
170                 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
171                             NULL, br_handle_local_finish)) {
172                         return RX_HANDLER_CONSUMED; /* consumed by filter */
173                 } else {
174                         *pskb = skb;
175                         return RX_HANDLER_PASS; /* continue processing */
176                 }
177         }
178
179 forward:
180         switch (p->state) {
181         case BR_STATE_FORWARDING:
182                 rhook = rcu_dereference(br_should_route_hook);
183                 if (rhook) {
184                         if ((*rhook)(skb)) {
185                                 *pskb = skb;
186                                 return RX_HANDLER_PASS;
187                         }
188                         dest = eth_hdr(skb)->h_dest;
189                 }
190                 /* fall through */
191         case BR_STATE_LEARNING:
192                 if (!compare_ether_addr(p->br->dev->dev_addr, dest))
193                         skb->pkt_type = PACKET_HOST;
194
195                 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
196                         br_handle_frame_finish);
197                 break;
198         default:
199 drop:
200                 kfree_skb(skb);
201         }
202         return RX_HANDLER_CONSUMED;
203 }