1 /* 2 * Forwarding decision 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/kernel.h> 15 #include <linux/netdevice.h> 16 #include <linux/skbuff.h> 17 #include <linux/if_vlan.h> 18 #include <linux/netfilter_bridge.h> 19 #include "br_private.h" 20 21 /* Don't forward packets to originating port or forwarding diasabled */ 22 static inline int should_deliver(const struct net_bridge_port *p, 23 const struct sk_buff *skb) 24 { 25 return (skb->dev != p->dev && p->state == BR_STATE_FORWARDING); 26 } 27 28 static inline unsigned packet_length(const struct sk_buff *skb) 29 { 30 return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0); 31 } 32 33 int br_dev_queue_push_xmit(struct sk_buff *skb) 34 { 35 /* drop mtu oversized packets except gso */ 36 if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb)) 37 kfree_skb(skb); 38 else { 39 /* ip_refrag calls ip_fragment, doesn't copy the MAC header. */ 40 if (nf_bridge_maybe_copy_header(skb)) 41 kfree_skb(skb); 42 else { 43 skb_push(skb, ETH_HLEN); 44 45 dev_queue_xmit(skb); 46 } 47 } 48 49 return 0; 50 } 51 52 int br_forward_finish(struct sk_buff *skb) 53 { 54 return NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev, 55 br_dev_queue_push_xmit); 56 57 } 58 59 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb) 60 { 61 skb->dev = to->dev; 62 NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev, 63 br_forward_finish); 64 } 65 66 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb) 67 { 68 struct net_device *indev; 69 70 if (skb_warn_if_lro(skb)) { 71 kfree_skb(skb); 72 return; 73 } 74 75 indev = skb->dev; 76 skb->dev = to->dev; 77 skb_forward_csum(skb); 78 79 NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev, 80 br_forward_finish); 81 } 82 83 /* called with rcu_read_lock */ 84 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb) 85 { 86 if (should_deliver(to, skb)) { 87 __br_deliver(to, skb); 88 return; 89 } 90 91 kfree_skb(skb); 92 } 93 94 /* called with rcu_read_lock */ 95 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb) 96 { 97 if (should_deliver(to, skb)) { 98 __br_forward(to, skb); 99 return; 100 } 101 102 kfree_skb(skb); 103 } 104 105 /* called under bridge lock */ 106 static void br_flood(struct net_bridge *br, struct sk_buff *skb, 107 void (*__packet_hook)(const struct net_bridge_port *p, 108 struct sk_buff *skb)) 109 { 110 struct net_bridge_port *p; 111 struct net_bridge_port *prev; 112 113 prev = NULL; 114 115 list_for_each_entry_rcu(p, &br->port_list, list) { 116 if (should_deliver(p, skb)) { 117 if (prev != NULL) { 118 struct sk_buff *skb2; 119 120 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) { 121 br->dev->stats.tx_dropped++; 122 kfree_skb(skb); 123 return; 124 } 125 126 __packet_hook(prev, skb2); 127 } 128 129 prev = p; 130 } 131 } 132 133 if (prev != NULL) { 134 __packet_hook(prev, skb); 135 return; 136 } 137 138 kfree_skb(skb); 139 } 140 141 142 /* called with rcu_read_lock */ 143 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb) 144 { 145 br_flood(br, skb, __br_deliver); 146 } 147 148 /* called under bridge lock */ 149 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb) 150 { 151 br_flood(br, skb, __br_forward); 152 } 153