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 diasabled */ 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 static inline unsigned int packet_length(const struct sk_buff *skb) 39 { 40 return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0); 41 } 42 43 int br_dev_queue_push_xmit(struct sk_buff *skb) 44 { 45 /* ip_fragment doesn't copy the MAC header */ 46 if (nf_bridge_maybe_copy_header(skb) || 47 (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))) { 48 kfree_skb(skb); 49 } else { 50 skb_push(skb, ETH_HLEN); 51 br_drop_fake_rtable(skb); 52 dev_queue_xmit(skb); 53 } 54 55 return 0; 56 } 57 58 int br_forward_finish(struct sk_buff *skb) 59 { 60 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev, 61 br_dev_queue_push_xmit); 62 63 } 64 65 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb) 66 { 67 skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb); 68 if (!skb) 69 return; 70 71 skb->dev = to->dev; 72 73 if (unlikely(netpoll_tx_running(to->br->dev))) { 74 if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb)) 75 kfree_skb(skb); 76 else { 77 skb_push(skb, ETH_HLEN); 78 br_netpoll_send_skb(to, skb); 79 } 80 return; 81 } 82 83 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev, 84 br_forward_finish); 85 } 86 87 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb) 88 { 89 struct net_device *indev; 90 91 if (skb_warn_if_lro(skb)) { 92 kfree_skb(skb); 93 return; 94 } 95 96 skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb); 97 if (!skb) 98 return; 99 100 indev = skb->dev; 101 skb->dev = to->dev; 102 skb_forward_csum(skb); 103 104 NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev, 105 br_forward_finish); 106 } 107 108 /* called with rcu_read_lock */ 109 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb) 110 { 111 if (to && should_deliver(to, skb)) { 112 __br_deliver(to, skb); 113 return; 114 } 115 116 kfree_skb(skb); 117 } 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 prev = maybe_deliver(prev, p, skb, __packet_hook); 190 if (IS_ERR(prev)) 191 goto out; 192 } 193 194 if (!prev) 195 goto out; 196 197 if (skb0) 198 deliver_clone(prev, skb, __packet_hook); 199 else 200 __packet_hook(prev, skb); 201 return; 202 203 out: 204 if (!skb0) 205 kfree_skb(skb); 206 } 207 208 209 /* called with rcu_read_lock */ 210 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, bool unicast) 211 { 212 br_flood(br, skb, NULL, __br_deliver, unicast); 213 } 214 215 /* called under bridge lock */ 216 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb, 217 struct sk_buff *skb2, bool unicast) 218 { 219 br_flood(br, skb, skb2, __br_forward, unicast); 220 } 221 222 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING 223 /* called with rcu_read_lock */ 224 static void br_multicast_flood(struct net_bridge_mdb_entry *mdst, 225 struct sk_buff *skb, struct sk_buff *skb0, 226 void (*__packet_hook)( 227 const struct net_bridge_port *p, 228 struct sk_buff *skb)) 229 { 230 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 231 struct net_bridge *br = netdev_priv(dev); 232 struct net_bridge_port *prev = NULL; 233 struct net_bridge_port_group *p; 234 struct hlist_node *rp; 235 236 rp = rcu_dereference(hlist_first_rcu(&br->router_list)); 237 p = mdst ? rcu_dereference(mdst->ports) : NULL; 238 while (p || rp) { 239 struct net_bridge_port *port, *lport, *rport; 240 241 lport = p ? p->port : NULL; 242 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) : 243 NULL; 244 245 port = (unsigned long)lport > (unsigned long)rport ? 246 lport : rport; 247 248 prev = maybe_deliver(prev, port, skb, __packet_hook); 249 if (IS_ERR(prev)) 250 goto out; 251 252 if ((unsigned long)lport >= (unsigned long)port) 253 p = rcu_dereference(p->next); 254 if ((unsigned long)rport >= (unsigned long)port) 255 rp = rcu_dereference(hlist_next_rcu(rp)); 256 } 257 258 if (!prev) 259 goto out; 260 261 if (skb0) 262 deliver_clone(prev, skb, __packet_hook); 263 else 264 __packet_hook(prev, skb); 265 return; 266 267 out: 268 if (!skb0) 269 kfree_skb(skb); 270 } 271 272 /* called with rcu_read_lock */ 273 void br_multicast_deliver(struct net_bridge_mdb_entry *mdst, 274 struct sk_buff *skb) 275 { 276 br_multicast_flood(mdst, skb, NULL, __br_deliver); 277 } 278 279 /* called with rcu_read_lock */ 280 void br_multicast_forward(struct net_bridge_mdb_entry *mdst, 281 struct sk_buff *skb, struct sk_buff *skb2) 282 { 283 br_multicast_flood(mdst, skb, skb2, __br_forward); 284 } 285 #endif 286