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 struct net_bridge_vlan_group *vg; 34 35 vg = nbp_vlan_group_rcu(p); 36 return ((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) && 37 br_allowed_egress(vg, skb) && p->state == BR_STATE_FORWARDING; 38 } 39 40 int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb) 41 { 42 if (!is_skb_forwardable(skb->dev, skb)) 43 goto drop; 44 45 skb_push(skb, ETH_HLEN); 46 br_drop_fake_rtable(skb); 47 48 if (skb->ip_summed == CHECKSUM_PARTIAL && 49 (skb->protocol == htons(ETH_P_8021Q) || 50 skb->protocol == htons(ETH_P_8021AD))) { 51 int depth; 52 53 if (!__vlan_get_protocol(skb, skb->protocol, &depth)) 54 goto drop; 55 56 skb_set_network_header(skb, depth); 57 } 58 59 dev_queue_xmit(skb); 60 61 return 0; 62 63 drop: 64 kfree_skb(skb); 65 return 0; 66 } 67 EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit); 68 69 int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 70 { 71 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, 72 net, sk, skb, NULL, skb->dev, 73 br_dev_queue_push_xmit); 74 75 } 76 EXPORT_SYMBOL_GPL(br_forward_finish); 77 78 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb) 79 { 80 struct net_bridge_vlan_group *vg; 81 82 vg = nbp_vlan_group_rcu(to); 83 skb = br_handle_vlan(to->br, vg, skb); 84 if (!skb) 85 return; 86 87 skb->dev = to->dev; 88 89 if (unlikely(netpoll_tx_running(to->br->dev))) { 90 if (!is_skb_forwardable(skb->dev, skb)) 91 kfree_skb(skb); 92 else { 93 skb_push(skb, ETH_HLEN); 94 br_netpoll_send_skb(to, skb); 95 } 96 return; 97 } 98 99 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, 100 dev_net(skb->dev), NULL, skb,NULL, skb->dev, 101 br_forward_finish); 102 } 103 104 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb) 105 { 106 struct net_bridge_vlan_group *vg; 107 struct net_device *indev; 108 109 if (skb_warn_if_lro(skb)) { 110 kfree_skb(skb); 111 return; 112 } 113 114 vg = nbp_vlan_group_rcu(to); 115 skb = br_handle_vlan(to->br, vg, skb); 116 if (!skb) 117 return; 118 119 indev = skb->dev; 120 skb->dev = to->dev; 121 skb_forward_csum(skb); 122 123 NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD, 124 dev_net(indev), NULL, skb, indev, skb->dev, 125 br_forward_finish); 126 } 127 128 /* called with rcu_read_lock */ 129 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb) 130 { 131 if (to && should_deliver(to, skb)) { 132 __br_deliver(to, skb); 133 return; 134 } 135 136 kfree_skb(skb); 137 } 138 EXPORT_SYMBOL_GPL(br_deliver); 139 140 /* called with rcu_read_lock */ 141 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0) 142 { 143 if (to && should_deliver(to, skb)) { 144 if (skb0) 145 deliver_clone(to, skb, __br_forward); 146 else 147 __br_forward(to, skb); 148 return; 149 } 150 151 if (!skb0) 152 kfree_skb(skb); 153 } 154 155 static int deliver_clone(const struct net_bridge_port *prev, 156 struct sk_buff *skb, 157 void (*__packet_hook)(const struct net_bridge_port *p, 158 struct sk_buff *skb)) 159 { 160 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 161 162 skb = skb_clone(skb, GFP_ATOMIC); 163 if (!skb) { 164 dev->stats.tx_dropped++; 165 return -ENOMEM; 166 } 167 168 __packet_hook(prev, skb); 169 return 0; 170 } 171 172 static struct net_bridge_port *maybe_deliver( 173 struct net_bridge_port *prev, struct net_bridge_port *p, 174 struct sk_buff *skb, 175 void (*__packet_hook)(const struct net_bridge_port *p, 176 struct sk_buff *skb)) 177 { 178 int err; 179 180 if (!should_deliver(p, skb)) 181 return prev; 182 183 if (!prev) 184 goto out; 185 186 err = deliver_clone(prev, skb, __packet_hook); 187 if (err) 188 return ERR_PTR(err); 189 190 out: 191 return p; 192 } 193 194 /* called under bridge lock */ 195 static void br_flood(struct net_bridge *br, struct sk_buff *skb, 196 struct sk_buff *skb0, 197 void (*__packet_hook)(const struct net_bridge_port *p, 198 struct sk_buff *skb), 199 bool unicast) 200 { 201 struct net_bridge_port *p; 202 struct net_bridge_port *prev; 203 204 prev = NULL; 205 206 list_for_each_entry_rcu(p, &br->port_list, list) { 207 /* Do not flood unicast traffic to ports that turn it off */ 208 if (unicast && !(p->flags & BR_FLOOD)) 209 continue; 210 211 /* Do not flood to ports that enable proxy ARP */ 212 if (p->flags & BR_PROXYARP) 213 continue; 214 if ((p->flags & BR_PROXYARP_WIFI) && 215 BR_INPUT_SKB_CB(skb)->proxyarp_replied) 216 continue; 217 218 prev = maybe_deliver(prev, p, skb, __packet_hook); 219 if (IS_ERR(prev)) 220 goto out; 221 } 222 223 if (!prev) 224 goto out; 225 226 if (skb0) 227 deliver_clone(prev, skb, __packet_hook); 228 else 229 __packet_hook(prev, skb); 230 return; 231 232 out: 233 if (!skb0) 234 kfree_skb(skb); 235 } 236 237 238 /* called with rcu_read_lock */ 239 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, bool unicast) 240 { 241 br_flood(br, skb, NULL, __br_deliver, unicast); 242 } 243 244 /* called under bridge lock */ 245 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb, 246 struct sk_buff *skb2, bool unicast) 247 { 248 br_flood(br, skb, skb2, __br_forward, unicast); 249 } 250 251 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING 252 /* called with rcu_read_lock */ 253 static void br_multicast_flood(struct net_bridge_mdb_entry *mdst, 254 struct sk_buff *skb, struct sk_buff *skb0, 255 void (*__packet_hook)( 256 const struct net_bridge_port *p, 257 struct sk_buff *skb)) 258 { 259 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 260 struct net_bridge *br = netdev_priv(dev); 261 struct net_bridge_port *prev = NULL; 262 struct net_bridge_port_group *p; 263 struct hlist_node *rp; 264 265 rp = rcu_dereference(hlist_first_rcu(&br->router_list)); 266 p = mdst ? rcu_dereference(mdst->ports) : NULL; 267 while (p || rp) { 268 struct net_bridge_port *port, *lport, *rport; 269 270 lport = p ? p->port : NULL; 271 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) : 272 NULL; 273 274 port = (unsigned long)lport > (unsigned long)rport ? 275 lport : rport; 276 277 prev = maybe_deliver(prev, port, skb, __packet_hook); 278 if (IS_ERR(prev)) 279 goto out; 280 281 if ((unsigned long)lport >= (unsigned long)port) 282 p = rcu_dereference(p->next); 283 if ((unsigned long)rport >= (unsigned long)port) 284 rp = rcu_dereference(hlist_next_rcu(rp)); 285 } 286 287 if (!prev) 288 goto out; 289 290 if (skb0) 291 deliver_clone(prev, skb, __packet_hook); 292 else 293 __packet_hook(prev, skb); 294 return; 295 296 out: 297 if (!skb0) 298 kfree_skb(skb); 299 } 300 301 /* called with rcu_read_lock */ 302 void br_multicast_deliver(struct net_bridge_mdb_entry *mdst, 303 struct sk_buff *skb) 304 { 305 br_multicast_flood(mdst, skb, NULL, __br_deliver); 306 } 307 308 /* called with rcu_read_lock */ 309 void br_multicast_forward(struct net_bridge_mdb_entry *mdst, 310 struct sk_buff *skb, struct sk_buff *skb2) 311 { 312 br_multicast_flood(mdst, skb, skb2, __br_forward); 313 } 314 #endif 315