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 /* ip_refrag calls ip_fragment, doesn't copy the MAC header. */ 42 if (nf_bridge_maybe_copy_header(skb)) 43 kfree_skb(skb); 44 else { 45 skb_push(skb, ETH_HLEN); 46 47 dev_queue_xmit(skb); 48 } 49 } 50 51 return 0; 52 } 53 54 int br_forward_finish(struct sk_buff *skb) 55 { 56 return NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev, 57 br_dev_queue_push_xmit); 58 59 } 60 61 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb) 62 { 63 skb->dev = to->dev; 64 NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev, 65 br_forward_finish); 66 } 67 68 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb) 69 { 70 struct net_device *indev; 71 72 indev = skb->dev; 73 skb->dev = to->dev; 74 skb_forward_csum(skb); 75 76 NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev, 77 br_forward_finish); 78 } 79 80 /* called with rcu_read_lock */ 81 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb) 82 { 83 if (should_deliver(to, skb)) { 84 __br_deliver(to, skb); 85 return; 86 } 87 88 kfree_skb(skb); 89 } 90 91 /* called with rcu_read_lock */ 92 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb) 93 { 94 if (should_deliver(to, skb)) { 95 __br_forward(to, skb); 96 return; 97 } 98 99 kfree_skb(skb); 100 } 101 102 /* called under bridge lock */ 103 static void br_flood(struct net_bridge *br, struct sk_buff *skb, int clone, 104 void (*__packet_hook)(const struct net_bridge_port *p, 105 struct sk_buff *skb)) 106 { 107 struct net_bridge_port *p; 108 struct net_bridge_port *prev; 109 110 if (clone) { 111 struct sk_buff *skb2; 112 113 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) { 114 br->statistics.tx_dropped++; 115 return; 116 } 117 118 skb = skb2; 119 } 120 121 prev = NULL; 122 123 list_for_each_entry_rcu(p, &br->port_list, list) { 124 if (should_deliver(p, skb)) { 125 if (prev != NULL) { 126 struct sk_buff *skb2; 127 128 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) { 129 br->statistics.tx_dropped++; 130 kfree_skb(skb); 131 return; 132 } 133 134 __packet_hook(prev, skb2); 135 } 136 137 prev = p; 138 } 139 } 140 141 if (prev != NULL) { 142 __packet_hook(prev, skb); 143 return; 144 } 145 146 kfree_skb(skb); 147 } 148 149 150 /* called with rcu_read_lock */ 151 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, int clone) 152 { 153 br_flood(br, skb, clone, __br_deliver); 154 } 155 156 /* called under bridge lock */ 157 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb, int clone) 158 { 159 br_flood(br, skb, clone, __br_forward); 160 } 161