1 /* 2 * Forwarding decision 3 * Linux ethernet bridge 4 * 5 * Authors: 6 * Lennert Buytenhek <buytenh@gnu.org> 7 * 8 * $Id: br_forward.c,v 1.4 2001/08/14 22:05:57 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/skbuff.h> 19 #include <linux/if_vlan.h> 20 #include <linux/netfilter_bridge.h> 21 #include "br_private.h" 22 23 /* Don't forward packets to originating port or forwarding diasabled */ 24 static inline int should_deliver(const struct net_bridge_port *p, 25 const struct sk_buff *skb) 26 { 27 return (skb->dev != p->dev && p->state == BR_STATE_FORWARDING); 28 } 29 30 static inline unsigned packet_length(const struct sk_buff *skb) 31 { 32 return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0); 33 } 34 35 int br_dev_queue_push_xmit(struct sk_buff *skb) 36 { 37 /* drop mtu oversized packets except gso */ 38 if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb)) 39 kfree_skb(skb); 40 else { 41 #ifdef CONFIG_BRIDGE_NETFILTER 42 /* ip_refrag calls ip_fragment, doesn't copy the MAC header. */ 43 nf_bridge_maybe_copy_header(skb); 44 #endif 45 skb_push(skb, ETH_HLEN); 46 47 dev_queue_xmit(skb); 48 } 49 50 return 0; 51 } 52 53 int br_forward_finish(struct sk_buff *skb) 54 { 55 return NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev, 56 br_dev_queue_push_xmit); 57 58 } 59 60 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb) 61 { 62 skb->dev = to->dev; 63 NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev, 64 br_forward_finish); 65 } 66 67 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb) 68 { 69 struct net_device *indev; 70 71 indev = skb->dev; 72 skb->dev = to->dev; 73 skb->ip_summed = CHECKSUM_NONE; 74 75 NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev, 76 br_forward_finish); 77 } 78 79 /* called with rcu_read_lock */ 80 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb) 81 { 82 if (should_deliver(to, skb)) { 83 __br_deliver(to, skb); 84 return; 85 } 86 87 kfree_skb(skb); 88 } 89 90 /* called with rcu_read_lock */ 91 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb) 92 { 93 if (should_deliver(to, skb)) { 94 __br_forward(to, skb); 95 return; 96 } 97 98 kfree_skb(skb); 99 } 100 101 /* called under bridge lock */ 102 static void br_flood(struct net_bridge *br, struct sk_buff *skb, int clone, 103 void (*__packet_hook)(const struct net_bridge_port *p, 104 struct sk_buff *skb)) 105 { 106 struct net_bridge_port *p; 107 struct net_bridge_port *prev; 108 109 if (clone) { 110 struct sk_buff *skb2; 111 112 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) { 113 br->statistics.tx_dropped++; 114 return; 115 } 116 117 skb = skb2; 118 } 119 120 prev = NULL; 121 122 list_for_each_entry_rcu(p, &br->port_list, list) { 123 if (should_deliver(p, skb)) { 124 if (prev != NULL) { 125 struct sk_buff *skb2; 126 127 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) { 128 br->statistics.tx_dropped++; 129 kfree_skb(skb); 130 return; 131 } 132 133 __packet_hook(prev, skb2); 134 } 135 136 prev = p; 137 } 138 } 139 140 if (prev != NULL) { 141 __packet_hook(prev, skb); 142 return; 143 } 144 145 kfree_skb(skb); 146 } 147 148 149 /* called with rcu_read_lock */ 150 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, int clone) 151 { 152 br_flood(br, skb, clone, __br_deliver); 153 } 154 155 /* called under bridge lock */ 156 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb, int clone) 157 { 158 br_flood(br, skb, clone, __br_forward); 159 } 160