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 sock *sk, struct sk_buff *skb) 39 { 40 if (!is_skb_forwardable(skb->dev, skb)) { 41 kfree_skb(skb); 42 } else { 43 skb_push(skb, ETH_HLEN); 44 br_drop_fake_rtable(skb); 45 skb_sender_cpu_clear(skb); 46 dev_queue_xmit(skb); 47 } 48 49 return 0; 50 } 51 EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit); 52 53 int br_forward_finish(struct sock *sk, struct sk_buff *skb) 54 { 55 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, sk, skb, 56 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, NULL, skb, 81 NULL, skb->dev, 82 br_forward_finish); 83 } 84 85 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb) 86 { 87 struct net_device *indev; 88 89 if (skb_warn_if_lro(skb)) { 90 kfree_skb(skb); 91 return; 92 } 93 94 skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb); 95 if (!skb) 96 return; 97 98 indev = skb->dev; 99 skb->dev = to->dev; 100 skb_forward_csum(skb); 101 102 NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD, NULL, skb, 103 indev, skb->dev, 104 br_forward_finish); 105 } 106 107 /* called with rcu_read_lock */ 108 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb) 109 { 110 if (to && should_deliver(to, skb)) { 111 __br_deliver(to, skb); 112 return; 113 } 114 115 kfree_skb(skb); 116 } 117 EXPORT_SYMBOL_GPL(br_deliver); 118 119 /* called with rcu_read_lock */ 120 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0) 121 { 122 if (should_deliver(to, skb)) { 123 if (skb0) 124 deliver_clone(to, skb, __br_forward); 125 else 126 __br_forward(to, skb); 127 return; 128 } 129 130 if (!skb0) 131 kfree_skb(skb); 132 } 133 134 static int deliver_clone(const struct net_bridge_port *prev, 135 struct sk_buff *skb, 136 void (*__packet_hook)(const struct net_bridge_port *p, 137 struct sk_buff *skb)) 138 { 139 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 140 141 skb = skb_clone(skb, GFP_ATOMIC); 142 if (!skb) { 143 dev->stats.tx_dropped++; 144 return -ENOMEM; 145 } 146 147 __packet_hook(prev, skb); 148 return 0; 149 } 150 151 static struct net_bridge_port *maybe_deliver( 152 struct net_bridge_port *prev, struct net_bridge_port *p, 153 struct sk_buff *skb, 154 void (*__packet_hook)(const struct net_bridge_port *p, 155 struct sk_buff *skb)) 156 { 157 int err; 158 159 if (!should_deliver(p, skb)) 160 return prev; 161 162 if (!prev) 163 goto out; 164 165 err = deliver_clone(prev, skb, __packet_hook); 166 if (err) 167 return ERR_PTR(err); 168 169 out: 170 return p; 171 } 172 173 /* called under bridge lock */ 174 static void br_flood(struct net_bridge *br, struct sk_buff *skb, 175 struct sk_buff *skb0, 176 void (*__packet_hook)(const struct net_bridge_port *p, 177 struct sk_buff *skb), 178 bool unicast) 179 { 180 struct net_bridge_port *p; 181 struct net_bridge_port *prev; 182 183 prev = NULL; 184 185 list_for_each_entry_rcu(p, &br->port_list, list) { 186 /* Do not flood unicast traffic to ports that turn it off */ 187 if (unicast && !(p->flags & BR_FLOOD)) 188 continue; 189 190 /* Do not flood to ports that enable proxy ARP */ 191 if (p->flags & BR_PROXYARP) 192 continue; 193 if ((p->flags & BR_PROXYARP_WIFI) && 194 BR_INPUT_SKB_CB(skb)->proxyarp_replied) 195 continue; 196 197 prev = maybe_deliver(prev, p, skb, __packet_hook); 198 if (IS_ERR(prev)) 199 goto out; 200 } 201 202 if (!prev) 203 goto out; 204 205 if (skb0) 206 deliver_clone(prev, skb, __packet_hook); 207 else 208 __packet_hook(prev, skb); 209 return; 210 211 out: 212 if (!skb0) 213 kfree_skb(skb); 214 } 215 216 217 /* called with rcu_read_lock */ 218 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, bool unicast) 219 { 220 br_flood(br, skb, NULL, __br_deliver, unicast); 221 } 222 223 /* called under bridge lock */ 224 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb, 225 struct sk_buff *skb2, bool unicast) 226 { 227 br_flood(br, skb, skb2, __br_forward, unicast); 228 } 229 230 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING 231 /* called with rcu_read_lock */ 232 static void br_multicast_flood(struct net_bridge_mdb_entry *mdst, 233 struct sk_buff *skb, struct sk_buff *skb0, 234 void (*__packet_hook)( 235 const struct net_bridge_port *p, 236 struct sk_buff *skb)) 237 { 238 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 239 struct net_bridge *br = netdev_priv(dev); 240 struct net_bridge_port *prev = NULL; 241 struct net_bridge_port_group *p; 242 struct hlist_node *rp; 243 244 rp = rcu_dereference(hlist_first_rcu(&br->router_list)); 245 p = mdst ? rcu_dereference(mdst->ports) : NULL; 246 while (p || rp) { 247 struct net_bridge_port *port, *lport, *rport; 248 249 lport = p ? p->port : NULL; 250 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) : 251 NULL; 252 253 port = (unsigned long)lport > (unsigned long)rport ? 254 lport : rport; 255 256 prev = maybe_deliver(prev, port, skb, __packet_hook); 257 if (IS_ERR(prev)) 258 goto out; 259 260 if ((unsigned long)lport >= (unsigned long)port) 261 p = rcu_dereference(p->next); 262 if ((unsigned long)rport >= (unsigned long)port) 263 rp = rcu_dereference(hlist_next_rcu(rp)); 264 } 265 266 if (!prev) 267 goto out; 268 269 if (skb0) 270 deliver_clone(prev, skb, __packet_hook); 271 else 272 __packet_hook(prev, skb); 273 return; 274 275 out: 276 if (!skb0) 277 kfree_skb(skb); 278 } 279 280 /* called with rcu_read_lock */ 281 void br_multicast_deliver(struct net_bridge_mdb_entry *mdst, 282 struct sk_buff *skb) 283 { 284 br_multicast_flood(mdst, skb, NULL, __br_deliver); 285 } 286 287 /* called with rcu_read_lock */ 288 void br_multicast_forward(struct net_bridge_mdb_entry *mdst, 289 struct sk_buff *skb, struct sk_buff *skb2) 290 { 291 br_multicast_flood(mdst, skb, skb2, __br_forward); 292 } 293 #endif 294