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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 | |
28 | brdev->stats.rx_packets++; |
29 | brdev->stats.rx_bytes += skb->len; |
30 | |
31 | indev = skb->dev; |
32 | skb->dev = brdev; |
33 | |
34 | return NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL, |
35 | netif_receive_skb); |
36 | } |
37 | |
38 | /* note: already called with rcu_read_lock (preempt_disabled) */ |
39 | int br_handle_frame_finish(struct sk_buff *skb) |
40 | { |
41 | const unsigned char *dest = eth_hdr(skb)->h_dest; |
42 | struct net_bridge_port *p = rcu_dereference(skb->dev->br_port); |
43 | struct net_bridge *br; |
44 | struct net_bridge_fdb_entry *dst; |
45 | struct net_bridge_mdb_entry *mdst; |
46 | struct sk_buff *skb2; |
47 | |
48 | if (!p || p->state == BR_STATE_DISABLED) |
49 | goto drop; |
50 | |
51 | /* insert into forwarding database after filtering to avoid spoofing */ |
52 | br = p->br; |
53 | br_fdb_update(br, p, eth_hdr(skb)->h_source); |
54 | |
55 | if (is_multicast_ether_addr(dest) && |
56 | br_multicast_rcv(br, p, skb)) |
57 | goto drop; |
58 | |
59 | if (p->state == BR_STATE_LEARNING) |
60 | goto drop; |
61 | |
62 | BR_INPUT_SKB_CB(skb)->brdev = br->dev; |
63 | |
64 | /* The packet skb2 goes to the local host (NULL to skip). */ |
65 | skb2 = NULL; |
66 | |
67 | if (br->dev->flags & IFF_PROMISC) |
68 | skb2 = skb; |
69 | |
70 | dst = NULL; |
71 | |
72 | if (is_multicast_ether_addr(dest)) { |
73 | mdst = br_mdb_get(br, skb); |
74 | if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) { |
75 | if ((mdst && !hlist_unhashed(&mdst->mglist)) || |
76 | br_multicast_is_router(br)) |
77 | skb2 = skb; |
78 | br_multicast_forward(mdst, skb, skb2); |
79 | skb = NULL; |
80 | if (!skb2) |
81 | goto out; |
82 | } else |
83 | skb2 = skb; |
84 | |
85 | br->dev->stats.multicast++; |
86 | } else if ((dst = __br_fdb_get(br, dest)) && dst->is_local) { |
87 | skb2 = skb; |
88 | /* Do not forward the packet since it's local. */ |
89 | skb = NULL; |
90 | } |
91 | |
92 | if (skb) { |
93 | if (dst) |
94 | br_forward(dst->dst, skb, skb2); |
95 | else |
96 | br_flood_forward(br, skb, skb2); |
97 | } |
98 | |
99 | if (skb2) |
100 | return br_pass_frame_up(skb2); |
101 | |
102 | out: |
103 | return 0; |
104 | drop: |
105 | kfree_skb(skb); |
106 | goto out; |
107 | } |
108 | |
109 | /* note: already called with rcu_read_lock (preempt_disabled) */ |
110 | static int br_handle_local_finish(struct sk_buff *skb) |
111 | { |
112 | struct net_bridge_port *p = rcu_dereference(skb->dev->br_port); |
113 | |
114 | if (p) |
115 | br_fdb_update(p->br, p, eth_hdr(skb)->h_source); |
116 | return 0; /* process further */ |
117 | } |
118 | |
119 | /* Does address match the link local multicast address. |
120 | * 01:80:c2:00:00:0X |
121 | */ |
122 | static inline int is_link_local(const unsigned char *dest) |
123 | { |
124 | __be16 *a = (__be16 *)dest; |
125 | static const __be16 *b = (const __be16 *)br_group_address; |
126 | static const __be16 m = cpu_to_be16(0xfff0); |
127 | |
128 | return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0; |
129 | } |
130 | |
131 | /* |
132 | * Called via br_handle_frame_hook. |
133 | * Return NULL if skb is handled |
134 | * note: already called with rcu_read_lock (preempt_disabled) |
135 | */ |
136 | struct sk_buff *br_handle_frame(struct net_bridge_port *p, struct sk_buff *skb) |
137 | { |
138 | const unsigned char *dest = eth_hdr(skb)->h_dest; |
139 | int (*rhook)(struct sk_buff *skb); |
140 | |
141 | if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) |
142 | goto drop; |
143 | |
144 | skb = skb_share_check(skb, GFP_ATOMIC); |
145 | if (!skb) |
146 | return NULL; |
147 | |
148 | if (unlikely(is_link_local(dest))) { |
149 | /* Pause frames shouldn't be passed up by driver anyway */ |
150 | if (skb->protocol == htons(ETH_P_PAUSE)) |
151 | goto drop; |
152 | |
153 | /* If STP is turned off, then forward */ |
154 | if (p->br->stp_enabled == BR_NO_STP && dest[5] == 0) |
155 | goto forward; |
156 | |
157 | if (NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev, |
158 | NULL, br_handle_local_finish)) |
159 | return NULL; /* frame consumed by filter */ |
160 | else |
161 | return skb; /* continue processing */ |
162 | } |
163 | |
164 | forward: |
165 | switch (p->state) { |
166 | case BR_STATE_FORWARDING: |
167 | rhook = rcu_dereference(br_should_route_hook); |
168 | if (rhook != NULL) { |
169 | if (rhook(skb)) |
170 | return skb; |
171 | dest = eth_hdr(skb)->h_dest; |
172 | } |
173 | /* fall through */ |
174 | case BR_STATE_LEARNING: |
175 | if (!compare_ether_addr(p->br->dev->dev_addr, dest)) |
176 | skb->pkt_type = PACKET_HOST; |
177 | |
178 | NF_HOOK(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, |
179 | br_handle_frame_finish); |
180 | break; |
181 | default: |
182 | drop: |
183 | kfree_skb(skb); |
184 | } |
185 | return NULL; |
186 | } |
187 |
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od-2011-09-04
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