1 /* 2 * Handle incoming frames 3 * Linux ethernet bridge 4 * 5 * Authors: 6 * Lennert Buytenhek <buytenh@gnu.org> 7 * 8 * $Id: br_input.c,v 1.10 2001/12/24 04:50:20 davem Exp $ 9 * 10 * This program is free software; you can redistribute it and/or 11 * modify it under the terms of the GNU General Public License 12 * as published by the Free Software Foundation; either version 13 * 2 of the License, or (at your option) any later version. 14 */ 15 16 #include <linux/kernel.h> 17 #include <linux/netdevice.h> 18 #include <linux/etherdevice.h> 19 #include <linux/netfilter_bridge.h> 20 #include "br_private.h" 21 22 /* Bridge group multicast address 802.1d (pg 51). */ 23 const u8 br_group_address[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 }; 24 25 static void br_pass_frame_up(struct net_bridge *br, struct sk_buff *skb) 26 { 27 struct net_device *indev; 28 29 br->statistics.rx_packets++; 30 br->statistics.rx_bytes += skb->len; 31 32 indev = skb->dev; 33 skb->dev = br->dev; 34 35 NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL, 36 netif_receive_skb); 37 } 38 39 /* note: already called with rcu_read_lock (preempt_disabled) */ 40 int br_handle_frame_finish(struct sk_buff *skb) 41 { 42 const unsigned char *dest = eth_hdr(skb)->h_dest; 43 struct net_bridge_port *p = rcu_dereference(skb->dev->br_port); 44 struct net_bridge *br; 45 struct net_bridge_fdb_entry *dst; 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 (p->state == BR_STATE_LEARNING) 56 goto drop; 57 58 /* The packet skb2 goes to the local host (NULL to skip). */ 59 skb2 = NULL; 60 61 if (br->dev->flags & IFF_PROMISC) 62 skb2 = skb; 63 64 dst = NULL; 65 66 if (is_multicast_ether_addr(dest)) { 67 br->statistics.multicast++; 68 skb2 = skb; 69 } else if ((dst = __br_fdb_get(br, dest)) && dst->is_local) { 70 skb2 = skb; 71 /* Do not forward the packet since it's local. */ 72 skb = NULL; 73 } 74 75 if (skb2 == skb) 76 skb2 = skb_clone(skb, GFP_ATOMIC); 77 78 if (skb2) 79 br_pass_frame_up(br, skb2); 80 81 if (skb) { 82 if (dst) 83 br_forward(dst->dst, skb); 84 else 85 br_flood_forward(br, skb); 86 } 87 88 out: 89 return 0; 90 drop: 91 kfree_skb(skb); 92 goto out; 93 } 94 95 /* note: already called with rcu_read_lock (preempt_disabled) */ 96 static int br_handle_local_finish(struct sk_buff *skb) 97 { 98 struct net_bridge_port *p = rcu_dereference(skb->dev->br_port); 99 100 if (p) 101 br_fdb_update(p->br, p, eth_hdr(skb)->h_source); 102 return 0; /* process further */ 103 } 104 105 /* Does address match the link local multicast address. 106 * 01:80:c2:00:00:0X 107 */ 108 static inline int is_link_local(const unsigned char *dest) 109 { 110 __be16 *a = (__be16 *)dest; 111 static const __be16 *b = (const __be16 *)br_group_address; 112 static const __be16 m = cpu_to_be16(0xfff0); 113 114 return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0; 115 } 116 117 /* 118 * Called via br_handle_frame_hook. 119 * Return NULL if skb is handled 120 * note: already called with rcu_read_lock (preempt_disabled) 121 */ 122 struct sk_buff *br_handle_frame(struct net_bridge_port *p, struct sk_buff *skb) 123 { 124 const unsigned char *dest = eth_hdr(skb)->h_dest; 125 int (*rhook)(struct sk_buff *skb); 126 127 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 128 goto drop; 129 130 skb = skb_share_check(skb, GFP_ATOMIC); 131 if (!skb) 132 return NULL; 133 134 if (unlikely(is_link_local(dest))) { 135 /* Pause frames shouldn't be passed up by driver anyway */ 136 if (skb->protocol == htons(ETH_P_PAUSE)) 137 goto drop; 138 139 /* Process STP BPDU's through normal netif_receive_skb() path */ 140 if (p->br->stp_enabled != BR_NO_STP) { 141 if (NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev, 142 NULL, br_handle_local_finish)) 143 return NULL; 144 else 145 return skb; 146 } 147 } 148 149 switch (p->state) { 150 case BR_STATE_FORWARDING: 151 rhook = rcu_dereference(br_should_route_hook); 152 if (rhook != NULL) { 153 if (rhook(skb)) 154 return skb; 155 dest = eth_hdr(skb)->h_dest; 156 } 157 /* fall through */ 158 case BR_STATE_LEARNING: 159 if (!compare_ether_addr(p->br->dev->dev_addr, dest)) 160 skb->pkt_type = PACKET_HOST; 161 162 NF_HOOK(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, 163 br_handle_frame_finish); 164 break; 165 default: 166 drop: 167 kfree_skb(skb); 168 } 169 return NULL; 170 } 171