ipv4: flush route cache after change accept_local
[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 /* 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_broadcast_ether_addr(dest) && 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_broadcast_ether_addr(dest))
81                 skb2 = skb;
82         else if (is_multicast_ether_addr(dest)) {
83                 mdst = br_mdb_get(br, skb);
84                 if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) {
85                         if ((mdst && mdst->mglist) ||
86                             br_multicast_is_router(br))
87                                 skb2 = skb;
88                         br_multicast_forward(mdst, skb, skb2);
89                         skb = NULL;
90                         if (!skb2)
91                                 goto out;
92                 } else
93                         skb2 = skb;
94
95                 br->dev->stats.multicast++;
96         } else if ((dst = __br_fdb_get(br, dest)) && dst->is_local) {
97                 skb2 = skb;
98                 /* Do not forward the packet since it's local. */
99                 skb = NULL;
100         }
101
102         if (skb) {
103                 if (dst) {
104                         dst->used = jiffies;
105                         br_forward(dst->dst, skb, skb2);
106                 } else
107                         br_flood_forward(br, skb, skb2);
108         }
109
110         if (skb2)
111                 return br_pass_frame_up(skb2);
112
113 out:
114         return 0;
115 drop:
116         kfree_skb(skb);
117         goto out;
118 }
119
120 /* note: already called with rcu_read_lock */
121 static int br_handle_local_finish(struct sk_buff *skb)
122 {
123         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
124
125         br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
126         return 0;        /* process further */
127 }
128
129 /* Does address match the link local multicast address.
130  * 01:80:c2:00:00:0X
131  */
132 static inline int is_link_local(const unsigned char *dest)
133 {
134         __be16 *a = (__be16 *)dest;
135         static const __be16 *b = (const __be16 *)br_group_address;
136         static const __be16 m = cpu_to_be16(0xfff0);
137
138         return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0;
139 }
140
141 /*
142  * Return NULL if skb is handled
143  * note: already called with rcu_read_lock
144  */
145 rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
146 {
147         struct net_bridge_port *p;
148         struct sk_buff *skb = *pskb;
149         const unsigned char *dest = eth_hdr(skb)->h_dest;
150         br_should_route_hook_t *rhook;
151
152         if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
153                 return RX_HANDLER_PASS;
154
155         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
156                 goto drop;
157
158         skb = skb_share_check(skb, GFP_ATOMIC);
159         if (!skb)
160                 return RX_HANDLER_CONSUMED;
161
162         p = br_port_get_rcu(skb->dev);
163
164         if (unlikely(is_link_local(dest))) {
165                 /* Pause frames shouldn't be passed up by driver anyway */
166                 if (skb->protocol == htons(ETH_P_PAUSE))
167                         goto drop;
168
169                 /* If STP is turned off, then forward */
170                 if (p->br->stp_enabled == BR_NO_STP && dest[5] == 0)
171                         goto forward;
172
173                 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
174                             NULL, br_handle_local_finish)) {
175                         return RX_HANDLER_CONSUMED; /* consumed by filter */
176                 } else {
177                         *pskb = skb;
178                         return RX_HANDLER_PASS; /* continue processing */
179                 }
180         }
181
182 forward:
183         switch (p->state) {
184         case BR_STATE_FORWARDING:
185                 rhook = rcu_dereference(br_should_route_hook);
186                 if (rhook) {
187                         if ((*rhook)(skb)) {
188                                 *pskb = skb;
189                                 return RX_HANDLER_PASS;
190                         }
191                         dest = eth_hdr(skb)->h_dest;
192                 }
193                 /* fall through */
194         case BR_STATE_LEARNING:
195                 if (!compare_ether_addr(p->br->dev->dev_addr, dest))
196                         skb->pkt_type = PACKET_HOST;
197
198                 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
199                         br_handle_frame_finish);
200                 break;
201         default:
202 drop:
203                 kfree_skb(skb);
204         }
205         return RX_HANDLER_CONSUMED;
206 }