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 (((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) && 26 p->state == BR_STATE_FORWARDING); 27 } 28 29 static inline unsigned packet_length(const struct sk_buff *skb) 30 { 31 return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0); 32 } 33 34 int br_dev_queue_push_xmit(struct sk_buff *skb) 35 { 36 /* drop mtu oversized packets except gso */ 37 if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb)) 38 kfree_skb(skb); 39 else { 40 /* ip_refrag calls ip_fragment, doesn't copy the MAC header. */ 41 if (nf_bridge_maybe_copy_header(skb)) 42 kfree_skb(skb); 43 else { 44 skb_push(skb, ETH_HLEN); 45 46 dev_queue_xmit(skb); 47 } 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 if (skb_warn_if_lro(skb)) { 72 kfree_skb(skb); 73 return; 74 } 75 76 indev = skb->dev; 77 skb->dev = to->dev; 78 skb_forward_csum(skb); 79 80 NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev, 81 br_forward_finish); 82 } 83 84 /* called with rcu_read_lock */ 85 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb) 86 { 87 if (should_deliver(to, skb)) { 88 __br_deliver(to, skb); 89 return; 90 } 91 92 kfree_skb(skb); 93 } 94 95 /* called with rcu_read_lock */ 96 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb) 97 { 98 if (should_deliver(to, skb)) { 99 __br_forward(to, skb); 100 return; 101 } 102 103 kfree_skb(skb); 104 } 105 106 /* called under bridge lock */ 107 static void br_flood(struct net_bridge *br, struct sk_buff *skb, 108 void (*__packet_hook)(const struct net_bridge_port *p, 109 struct sk_buff *skb)) 110 { 111 struct net_bridge_port *p; 112 struct net_bridge_port *prev; 113 114 prev = NULL; 115 116 list_for_each_entry_rcu(p, &br->port_list, list) { 117 if (should_deliver(p, skb)) { 118 if (prev != NULL) { 119 struct sk_buff *skb2; 120 121 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) { 122 br->dev->stats.tx_dropped++; 123 kfree_skb(skb); 124 return; 125 } 126 127 __packet_hook(prev, skb2); 128 } 129 130 prev = p; 131 } 132 } 133 134 if (prev != NULL) { 135 __packet_hook(prev, skb); 136 return; 137 } 138 139 kfree_skb(skb); 140 } 141 142 143 /* called with rcu_read_lock */ 144 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb) 145 { 146 br_flood(br, skb, __br_deliver); 147 } 148 149 /* called under bridge lock */ 150 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb) 151 { 152 br_flood(br, skb, __br_forward); 153 } 154