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/slab.h> 16 #include <linux/kernel.h> 17 #include <linux/netdevice.h> 18 #include <linux/netpoll.h> 19 #include <linux/skbuff.h> 20 #include <linux/if_vlan.h> 21 #include <linux/netfilter_bridge.h> 22 #include "br_private.h" 23 24 static int deliver_clone(const struct net_bridge_port *prev, 25 struct sk_buff *skb, 26 void (*__packet_hook)(const struct net_bridge_port *p, 27 struct sk_buff *skb)); 28 29 /* Don't forward packets to originating port or forwarding disabled */ 30 static inline int should_deliver(const struct net_bridge_port *p, 31 const struct sk_buff *skb) 32 { 33 return ((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) && 34 br_allowed_egress(p->br, nbp_get_vlan_info(p), skb) && 35 p->state == BR_STATE_FORWARDING; 36 } 37 38 int br_dev_queue_push_xmit(struct sk_buff *skb) 39 { 40 /* ip_fragment doesn't copy the MAC header */ 41 if (nf_bridge_maybe_copy_header(skb) || 42 !is_skb_forwardable(skb->dev, skb)) { 43 kfree_skb(skb); 44 } else { 45 skb_push(skb, ETH_HLEN); 46 br_drop_fake_rtable(skb); 47 dev_queue_xmit(skb); 48 } 49 50 return 0; 51 } 52 EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit); 53 54 int br_forward_finish(struct sk_buff *skb) 55 { 56 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev, 57 br_dev_queue_push_xmit); 58 59 } 60 EXPORT_SYMBOL_GPL(br_forward_finish); 61 62 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb) 63 { 64 skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb); 65 if (!skb) 66 return; 67 68 skb->dev = to->dev; 69 70 if (unlikely(netpoll_tx_running(to->br->dev))) { 71 if (!is_skb_forwardable(skb->dev, skb)) 72 kfree_skb(skb); 73 else { 74 skb_push(skb, ETH_HLEN); 75 br_netpoll_send_skb(to, skb); 76 } 77 return; 78 } 79 80 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev, 81 br_forward_finish); 82 } 83 84 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb) 85 { 86 struct net_device *indev; 87 88 if (skb_warn_if_lro(skb)) { 89 kfree_skb(skb); 90 return; 91 } 92 93 skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb); 94 if (!skb) 95 return; 96 97 indev = skb->dev; 98 skb->dev = to->dev; 99 skb_forward_csum(skb); 100 101 NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev, 102 br_forward_finish); 103 } 104 105 /* called with rcu_read_lock */ 106 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb) 107 { 108 if (to && should_deliver(to, skb)) { 109 __br_deliver(to, skb); 110 return; 111 } 112 113 kfree_skb(skb); 114 } 115 116 /* called with rcu_read_lock */ 117 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0) 118 { 119 if (should_deliver(to, skb)) { 120 if (skb0) 121 deliver_clone(to, skb, __br_forward); 122 else 123 __br_forward(to, skb); 124 return; 125 } 126 127 if (!skb0) 128 kfree_skb(skb); 129 } 130 131 static int deliver_clone(const struct net_bridge_port *prev, 132 struct sk_buff *skb, 133 void (*__packet_hook)(const struct net_bridge_port *p, 134 struct sk_buff *skb)) 135 { 136 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 137 138 skb = skb_clone(skb, GFP_ATOMIC); 139 if (!skb) { 140 dev->stats.tx_dropped++; 141 return -ENOMEM; 142 } 143 144 __packet_hook(prev, skb); 145 return 0; 146 } 147 148 static struct net_bridge_port *maybe_deliver( 149 struct net_bridge_port *prev, struct net_bridge_port *p, 150 struct sk_buff *skb, 151 void (*__packet_hook)(const struct net_bridge_port *p, 152 struct sk_buff *skb)) 153 { 154 int err; 155 156 if (!should_deliver(p, skb)) 157 return prev; 158 159 if (!prev) 160 goto out; 161 162 err = deliver_clone(prev, skb, __packet_hook); 163 if (err) 164 return ERR_PTR(err); 165 166 out: 167 return p; 168 } 169 170 /* called under bridge lock */ 171 static void br_flood(struct net_bridge *br, struct sk_buff *skb, 172 struct sk_buff *skb0, 173 void (*__packet_hook)(const struct net_bridge_port *p, 174 struct sk_buff *skb), 175 bool unicast) 176 { 177 struct net_bridge_port *p; 178 struct net_bridge_port *prev; 179 180 prev = NULL; 181 182 list_for_each_entry_rcu(p, &br->port_list, list) { 183 /* Do not flood unicast traffic to ports that turn it off */ 184 if (unicast && !(p->flags & BR_FLOOD)) 185 continue; 186 prev = maybe_deliver(prev, p, skb, __packet_hook); 187 if (IS_ERR(prev)) 188 goto out; 189 } 190 191 if (!prev) 192 goto out; 193 194 if (skb0) 195 deliver_clone(prev, skb, __packet_hook); 196 else 197 __packet_hook(prev, skb); 198 return; 199 200 out: 201 if (!skb0) 202 kfree_skb(skb); 203 } 204 205 206 /* called with rcu_read_lock */ 207 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, bool unicast) 208 { 209 br_flood(br, skb, NULL, __br_deliver, unicast); 210 } 211 212 /* called under bridge lock */ 213 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb, 214 struct sk_buff *skb2, bool unicast) 215 { 216 br_flood(br, skb, skb2, __br_forward, unicast); 217 } 218 219 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING 220 /* called with rcu_read_lock */ 221 static void br_multicast_flood(struct net_bridge_mdb_entry *mdst, 222 struct sk_buff *skb, struct sk_buff *skb0, 223 void (*__packet_hook)( 224 const struct net_bridge_port *p, 225 struct sk_buff *skb)) 226 { 227 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 228 struct net_bridge *br = netdev_priv(dev); 229 struct net_bridge_port *prev = NULL; 230 struct net_bridge_port_group *p; 231 struct hlist_node *rp; 232 233 rp = rcu_dereference(hlist_first_rcu(&br->router_list)); 234 p = mdst ? rcu_dereference(mdst->ports) : NULL; 235 while (p || rp) { 236 struct net_bridge_port *port, *lport, *rport; 237 238 lport = p ? p->port : NULL; 239 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) : 240 NULL; 241 242 port = (unsigned long)lport > (unsigned long)rport ? 243 lport : rport; 244 245 prev = maybe_deliver(prev, port, skb, __packet_hook); 246 if (IS_ERR(prev)) 247 goto out; 248 249 if ((unsigned long)lport >= (unsigned long)port) 250 p = rcu_dereference(p->next); 251 if ((unsigned long)rport >= (unsigned long)port) 252 rp = rcu_dereference(hlist_next_rcu(rp)); 253 } 254 255 if (!prev) 256 goto out; 257 258 if (skb0) 259 deliver_clone(prev, skb, __packet_hook); 260 else 261 __packet_hook(prev, skb); 262 return; 263 264 out: 265 if (!skb0) 266 kfree_skb(skb); 267 } 268 269 /* called with rcu_read_lock */ 270 void br_multicast_deliver(struct net_bridge_mdb_entry *mdst, 271 struct sk_buff *skb) 272 { 273 br_multicast_flood(mdst, skb, NULL, __br_deliver); 274 } 275 276 /* called with rcu_read_lock */ 277 void br_multicast_forward(struct net_bridge_mdb_entry *mdst, 278 struct sk_buff *skb, struct sk_buff *skb2) 279 { 280 br_multicast_flood(mdst, skb, skb2, __br_forward); 281 } 282 #endif 283