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 /* Don't forward packets to originating port or forwarding disabled */ 25 static inline int should_deliver(const struct net_bridge_port *p, 26 const struct sk_buff *skb) 27 { 28 struct net_bridge_vlan_group *vg; 29 30 vg = nbp_vlan_group_rcu(p); 31 return ((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) && 32 br_allowed_egress(vg, skb) && p->state == BR_STATE_FORWARDING && 33 nbp_switchdev_allowed_egress(p, skb) && 34 !br_skb_isolated(p, skb); 35 } 36 37 int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb) 38 { 39 skb_push(skb, ETH_HLEN); 40 if (!is_skb_forwardable(skb->dev, skb)) 41 goto drop; 42 43 br_drop_fake_rtable(skb); 44 45 if (skb->ip_summed == CHECKSUM_PARTIAL && 46 (skb->protocol == htons(ETH_P_8021Q) || 47 skb->protocol == htons(ETH_P_8021AD))) { 48 int depth; 49 50 if (!__vlan_get_protocol(skb, skb->protocol, &depth)) 51 goto drop; 52 53 skb_set_network_header(skb, depth); 54 } 55 56 dev_queue_xmit(skb); 57 58 return 0; 59 60 drop: 61 kfree_skb(skb); 62 return 0; 63 } 64 EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit); 65 66 int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 67 { 68 skb->tstamp = 0; 69 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, 70 net, sk, skb, NULL, skb->dev, 71 br_dev_queue_push_xmit); 72 73 } 74 EXPORT_SYMBOL_GPL(br_forward_finish); 75 76 static void __br_forward(const struct net_bridge_port *to, 77 struct sk_buff *skb, bool local_orig) 78 { 79 struct net_bridge_vlan_group *vg; 80 struct net_device *indev; 81 struct net *net; 82 int br_hook; 83 84 vg = nbp_vlan_group_rcu(to); 85 skb = br_handle_vlan(to->br, to, vg, skb); 86 if (!skb) 87 return; 88 89 indev = skb->dev; 90 skb->dev = to->dev; 91 if (!local_orig) { 92 if (skb_warn_if_lro(skb)) { 93 kfree_skb(skb); 94 return; 95 } 96 br_hook = NF_BR_FORWARD; 97 skb_forward_csum(skb); 98 net = dev_net(indev); 99 } else { 100 if (unlikely(netpoll_tx_running(to->br->dev))) { 101 skb_push(skb, ETH_HLEN); 102 if (!is_skb_forwardable(skb->dev, skb)) 103 kfree_skb(skb); 104 else 105 br_netpoll_send_skb(to, skb); 106 return; 107 } 108 br_hook = NF_BR_LOCAL_OUT; 109 net = dev_net(skb->dev); 110 indev = NULL; 111 } 112 113 NF_HOOK(NFPROTO_BRIDGE, br_hook, 114 net, NULL, skb, indev, skb->dev, 115 br_forward_finish); 116 } 117 118 static int deliver_clone(const struct net_bridge_port *prev, 119 struct sk_buff *skb, bool local_orig) 120 { 121 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 122 123 skb = skb_clone(skb, GFP_ATOMIC); 124 if (!skb) { 125 dev->stats.tx_dropped++; 126 return -ENOMEM; 127 } 128 129 __br_forward(prev, skb, local_orig); 130 return 0; 131 } 132 133 /** 134 * br_forward - forward a packet to a specific port 135 * @to: destination port 136 * @skb: packet being forwarded 137 * @local_rcv: packet will be received locally after forwarding 138 * @local_orig: packet is locally originated 139 * 140 * Should be called with rcu_read_lock. 141 */ 142 void br_forward(const struct net_bridge_port *to, 143 struct sk_buff *skb, bool local_rcv, bool local_orig) 144 { 145 if (unlikely(!to)) 146 goto out; 147 148 /* redirect to backup link if the destination port is down */ 149 if (rcu_access_pointer(to->backup_port) && !netif_carrier_ok(to->dev)) { 150 struct net_bridge_port *backup_port; 151 152 backup_port = rcu_dereference(to->backup_port); 153 if (unlikely(!backup_port)) 154 goto out; 155 to = backup_port; 156 } 157 158 if (should_deliver(to, skb)) { 159 if (local_rcv) 160 deliver_clone(to, skb, local_orig); 161 else 162 __br_forward(to, skb, local_orig); 163 return; 164 } 165 166 out: 167 if (!local_rcv) 168 kfree_skb(skb); 169 } 170 EXPORT_SYMBOL_GPL(br_forward); 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, bool local_orig) 175 { 176 u8 igmp_type = br_multicast_igmp_type(skb); 177 int err; 178 179 if (!should_deliver(p, skb)) 180 return prev; 181 182 if (!prev) 183 goto out; 184 185 err = deliver_clone(prev, skb, local_orig); 186 if (err) 187 return ERR_PTR(err); 188 out: 189 br_multicast_count(p->br, p, skb, igmp_type, BR_MCAST_DIR_TX); 190 191 return p; 192 } 193 194 /* called under rcu_read_lock */ 195 void br_flood(struct net_bridge *br, struct sk_buff *skb, 196 enum br_pkt_type pkt_type, bool local_rcv, bool local_orig) 197 { 198 struct net_bridge_port *prev = NULL; 199 struct net_bridge_port *p; 200 201 list_for_each_entry_rcu(p, &br->port_list, list) { 202 /* Do not flood unicast traffic to ports that turn it off, nor 203 * other traffic if flood off, except for traffic we originate 204 */ 205 switch (pkt_type) { 206 case BR_PKT_UNICAST: 207 if (!(p->flags & BR_FLOOD)) 208 continue; 209 break; 210 case BR_PKT_MULTICAST: 211 if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev) 212 continue; 213 break; 214 case BR_PKT_BROADCAST: 215 if (!(p->flags & BR_BCAST_FLOOD) && skb->dev != br->dev) 216 continue; 217 break; 218 } 219 220 /* Do not flood to ports that enable proxy ARP */ 221 if (p->flags & BR_PROXYARP) 222 continue; 223 if ((p->flags & (BR_PROXYARP_WIFI | BR_NEIGH_SUPPRESS)) && 224 BR_INPUT_SKB_CB(skb)->proxyarp_replied) 225 continue; 226 227 prev = maybe_deliver(prev, p, skb, local_orig); 228 if (IS_ERR(prev)) 229 goto out; 230 } 231 232 if (!prev) 233 goto out; 234 235 if (local_rcv) 236 deliver_clone(prev, skb, local_orig); 237 else 238 __br_forward(prev, skb, local_orig); 239 return; 240 241 out: 242 if (!local_rcv) 243 kfree_skb(skb); 244 } 245 246 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING 247 static void maybe_deliver_addr(struct net_bridge_port *p, struct sk_buff *skb, 248 const unsigned char *addr, bool local_orig) 249 { 250 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 251 const unsigned char *src = eth_hdr(skb)->h_source; 252 253 if (!should_deliver(p, skb)) 254 return; 255 256 /* Even with hairpin, no soliloquies - prevent breaking IPv6 DAD */ 257 if (skb->dev == p->dev && ether_addr_equal(src, addr)) 258 return; 259 260 skb = skb_copy(skb, GFP_ATOMIC); 261 if (!skb) { 262 dev->stats.tx_dropped++; 263 return; 264 } 265 266 if (!is_broadcast_ether_addr(addr)) 267 memcpy(eth_hdr(skb)->h_dest, addr, ETH_ALEN); 268 269 __br_forward(p, skb, local_orig); 270 } 271 272 /* called with rcu_read_lock */ 273 void br_multicast_flood(struct net_bridge_mdb_entry *mdst, 274 struct sk_buff *skb, 275 bool local_rcv, bool local_orig) 276 { 277 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 278 struct net_bridge *br = netdev_priv(dev); 279 struct net_bridge_port *prev = NULL; 280 struct net_bridge_port_group *p; 281 struct hlist_node *rp; 282 283 rp = rcu_dereference(hlist_first_rcu(&br->router_list)); 284 p = mdst ? rcu_dereference(mdst->ports) : NULL; 285 while (p || rp) { 286 struct net_bridge_port *port, *lport, *rport; 287 288 lport = p ? p->port : NULL; 289 rport = hlist_entry_safe(rp, struct net_bridge_port, rlist); 290 291 if ((unsigned long)lport > (unsigned long)rport) { 292 port = lport; 293 294 if (port->flags & BR_MULTICAST_TO_UNICAST) { 295 maybe_deliver_addr(lport, skb, p->eth_addr, 296 local_orig); 297 goto delivered; 298 } 299 } else { 300 port = rport; 301 } 302 303 prev = maybe_deliver(prev, port, skb, local_orig); 304 if (IS_ERR(prev)) 305 goto out; 306 delivered: 307 if ((unsigned long)lport >= (unsigned long)port) 308 p = rcu_dereference(p->next); 309 if ((unsigned long)rport >= (unsigned long)port) 310 rp = rcu_dereference(hlist_next_rcu(rp)); 311 } 312 313 if (!prev) 314 goto out; 315 316 if (local_rcv) 317 deliver_clone(prev, skb, local_orig); 318 else 319 __br_forward(prev, skb, local_orig); 320 return; 321 322 out: 323 if (!local_rcv) 324 kfree_skb(skb); 325 } 326 #endif 327