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/err.h> 15 #include <linux/kernel.h> 16 #include <linux/netdevice.h> 17 #include <linux/skbuff.h> 18 #include <linux/if_vlan.h> 19 #include <linux/netfilter_bridge.h> 20 #include "br_private.h" 21 22 /* Don't forward packets to originating port or forwarding diasabled */ 23 static inline int should_deliver(const struct net_bridge_port *p, 24 const struct sk_buff *skb) 25 { 26 return (((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) && 27 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 if (skb_warn_if_lro(skb)) { 73 kfree_skb(skb); 74 return; 75 } 76 77 indev = skb->dev; 78 skb->dev = to->dev; 79 skb_forward_csum(skb); 80 81 NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev, 82 br_forward_finish); 83 } 84 85 /* called with rcu_read_lock */ 86 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb) 87 { 88 if (should_deliver(to, skb)) { 89 __br_deliver(to, skb); 90 return; 91 } 92 93 kfree_skb(skb); 94 } 95 96 /* called with rcu_read_lock */ 97 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb) 98 { 99 if (should_deliver(to, skb)) { 100 __br_forward(to, skb); 101 return; 102 } 103 104 kfree_skb(skb); 105 } 106 107 static int deliver_clone(struct net_bridge_port *prev, struct sk_buff *skb, 108 void (*__packet_hook)(const struct net_bridge_port *p, 109 struct sk_buff *skb)) 110 { 111 skb = skb_clone(skb, GFP_ATOMIC); 112 if (!skb) { 113 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 114 115 dev->stats.tx_dropped++; 116 return -ENOMEM; 117 } 118 119 __packet_hook(prev, skb); 120 return 0; 121 } 122 123 static struct net_bridge_port *maybe_deliver( 124 struct net_bridge_port *prev, struct net_bridge_port *p, 125 struct sk_buff *skb, 126 void (*__packet_hook)(const struct net_bridge_port *p, 127 struct sk_buff *skb)) 128 { 129 int err; 130 131 if (!should_deliver(p, skb)) 132 return prev; 133 134 if (!prev) 135 goto out; 136 137 err = deliver_clone(prev, skb, __packet_hook); 138 if (err) 139 return ERR_PTR(err); 140 141 out: 142 return p; 143 } 144 145 /* called under bridge lock */ 146 static void br_flood(struct net_bridge *br, struct sk_buff *skb, 147 struct sk_buff *skb0, 148 void (*__packet_hook)(const struct net_bridge_port *p, 149 struct sk_buff *skb)) 150 { 151 struct net_bridge_port *p; 152 struct net_bridge_port *prev; 153 154 prev = NULL; 155 156 list_for_each_entry_rcu(p, &br->port_list, list) { 157 prev = maybe_deliver(prev, p, skb, __packet_hook); 158 if (IS_ERR(prev)) 159 goto out; 160 } 161 162 if (!prev) 163 goto out; 164 165 if (skb0) 166 deliver_clone(prev, skb, __packet_hook); 167 else 168 __packet_hook(prev, skb); 169 return; 170 171 out: 172 if (!skb0) 173 kfree_skb(skb); 174 } 175 176 177 /* called with rcu_read_lock */ 178 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb) 179 { 180 br_flood(br, skb, NULL, __br_deliver); 181 } 182 183 /* called under bridge lock */ 184 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb, 185 struct sk_buff *skb2) 186 { 187 br_flood(br, skb, skb2, __br_forward); 188 } 189 190 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING 191 /* called with rcu_read_lock */ 192 static void br_multicast_flood(struct net_bridge_mdb_entry *mdst, 193 struct sk_buff *skb, struct sk_buff *skb0, 194 void (*__packet_hook)( 195 const struct net_bridge_port *p, 196 struct sk_buff *skb)) 197 { 198 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 199 struct net_bridge *br = netdev_priv(dev); 200 struct net_bridge_port *port; 201 struct net_bridge_port *lport, *rport; 202 struct net_bridge_port *prev; 203 struct net_bridge_port_group *p; 204 struct hlist_node *rp; 205 206 prev = NULL; 207 208 rp = br->router_list.first; 209 p = mdst ? mdst->ports : NULL; 210 while (p || rp) { 211 lport = p ? p->port : NULL; 212 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) : 213 NULL; 214 215 port = (unsigned long)lport > (unsigned long)rport ? 216 lport : rport; 217 218 prev = maybe_deliver(prev, port, skb, __packet_hook); 219 if (IS_ERR(prev)) 220 goto out; 221 222 if ((unsigned long)lport >= (unsigned long)port) 223 p = p->next; 224 if ((unsigned long)rport >= (unsigned long)port) 225 rp = rp->next; 226 } 227 228 if (!prev) 229 goto out; 230 231 if (skb0) 232 deliver_clone(prev, skb, __packet_hook); 233 else 234 __packet_hook(prev, skb); 235 return; 236 237 out: 238 if (!skb0) 239 kfree_skb(skb); 240 } 241 242 /* called with rcu_read_lock */ 243 void br_multicast_deliver(struct net_bridge_mdb_entry *mdst, 244 struct sk_buff *skb) 245 { 246 br_multicast_flood(mdst, skb, NULL, __br_deliver); 247 } 248 249 /* called with rcu_read_lock */ 250 void br_multicast_forward(struct net_bridge_mdb_entry *mdst, 251 struct sk_buff *skb, struct sk_buff *skb2) 252 { 253 br_multicast_flood(mdst, skb, skb2, __br_forward); 254 } 255 #endif 256