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 } 35 36 int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb) 37 { 38 if (!is_skb_forwardable(skb->dev, skb)) 39 goto drop; 40 41 skb_push(skb, ETH_HLEN); 42 br_drop_fake_rtable(skb); 43 44 if (skb->ip_summed == CHECKSUM_PARTIAL && 45 (skb->protocol == htons(ETH_P_8021Q) || 46 skb->protocol == htons(ETH_P_8021AD))) { 47 int depth; 48 49 if (!__vlan_get_protocol(skb, skb->protocol, &depth)) 50 goto drop; 51 52 skb_set_network_header(skb, depth); 53 } 54 55 dev_queue_xmit(skb); 56 57 return 0; 58 59 drop: 60 kfree_skb(skb); 61 return 0; 62 } 63 EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit); 64 65 int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 66 { 67 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, 68 net, sk, skb, NULL, skb->dev, 69 br_dev_queue_push_xmit); 70 71 } 72 EXPORT_SYMBOL_GPL(br_forward_finish); 73 74 static void __br_forward(const struct net_bridge_port *to, 75 struct sk_buff *skb, bool local_orig) 76 { 77 struct net_bridge_vlan_group *vg; 78 struct net_device *indev; 79 struct net *net; 80 int br_hook; 81 82 vg = nbp_vlan_group_rcu(to); 83 skb = br_handle_vlan(to->br, to, vg, skb); 84 if (!skb) 85 return; 86 87 indev = skb->dev; 88 skb->dev = to->dev; 89 if (!local_orig) { 90 if (skb_warn_if_lro(skb)) { 91 kfree_skb(skb); 92 return; 93 } 94 br_hook = NF_BR_FORWARD; 95 skb_forward_csum(skb); 96 net = dev_net(indev); 97 } else { 98 if (unlikely(netpoll_tx_running(to->br->dev))) { 99 if (!is_skb_forwardable(skb->dev, skb)) { 100 kfree_skb(skb); 101 } else { 102 skb_push(skb, ETH_HLEN); 103 br_netpoll_send_skb(to, skb); 104 } 105 return; 106 } 107 br_hook = NF_BR_LOCAL_OUT; 108 net = dev_net(skb->dev); 109 indev = NULL; 110 } 111 112 NF_HOOK(NFPROTO_BRIDGE, br_hook, 113 net, NULL, skb, indev, skb->dev, 114 br_forward_finish); 115 } 116 117 static int deliver_clone(const struct net_bridge_port *prev, 118 struct sk_buff *skb, bool local_orig) 119 { 120 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 121 122 skb = skb_clone(skb, GFP_ATOMIC); 123 if (!skb) { 124 dev->stats.tx_dropped++; 125 return -ENOMEM; 126 } 127 128 __br_forward(prev, skb, local_orig); 129 return 0; 130 } 131 132 /** 133 * br_forward - forward a packet to a specific port 134 * @to: destination port 135 * @skb: packet being forwarded 136 * @local_rcv: packet will be received locally after forwarding 137 * @local_orig: packet is locally originated 138 * 139 * Should be called with rcu_read_lock. 140 */ 141 void br_forward(const struct net_bridge_port *to, 142 struct sk_buff *skb, bool local_rcv, bool local_orig) 143 { 144 if (to && should_deliver(to, skb)) { 145 if (local_rcv) 146 deliver_clone(to, skb, local_orig); 147 else 148 __br_forward(to, skb, local_orig); 149 return; 150 } 151 152 if (!local_rcv) 153 kfree_skb(skb); 154 } 155 EXPORT_SYMBOL_GPL(br_forward); 156 157 static struct net_bridge_port *maybe_deliver( 158 struct net_bridge_port *prev, struct net_bridge_port *p, 159 struct sk_buff *skb, bool local_orig) 160 { 161 int err; 162 163 if (!should_deliver(p, skb)) 164 return prev; 165 166 if (!prev) 167 goto out; 168 169 err = deliver_clone(prev, skb, local_orig); 170 if (err) 171 return ERR_PTR(err); 172 173 out: 174 return p; 175 } 176 177 /* called under rcu_read_lock */ 178 void br_flood(struct net_bridge *br, struct sk_buff *skb, 179 enum br_pkt_type pkt_type, bool local_rcv, bool local_orig) 180 { 181 u8 igmp_type = br_multicast_igmp_type(skb); 182 struct net_bridge_port *prev = NULL; 183 struct net_bridge_port *p; 184 185 list_for_each_entry_rcu(p, &br->port_list, list) { 186 /* Do not flood unicast traffic to ports that turn it off, nor 187 * other traffic if flood off, except for traffic we originate 188 */ 189 switch (pkt_type) { 190 case BR_PKT_UNICAST: 191 if (!(p->flags & BR_FLOOD)) 192 continue; 193 break; 194 case BR_PKT_MULTICAST: 195 if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev) 196 continue; 197 break; 198 case BR_PKT_BROADCAST: 199 if (!(p->flags & BR_BCAST_FLOOD) && skb->dev != br->dev) 200 continue; 201 break; 202 } 203 204 /* Do not flood to ports that enable proxy ARP */ 205 if (p->flags & BR_PROXYARP) 206 continue; 207 if ((p->flags & BR_PROXYARP_WIFI) && 208 BR_INPUT_SKB_CB(skb)->proxyarp_replied) 209 continue; 210 211 prev = maybe_deliver(prev, p, skb, local_orig); 212 if (IS_ERR(prev)) 213 goto out; 214 if (prev == p) 215 br_multicast_count(p->br, p, skb, igmp_type, 216 BR_MCAST_DIR_TX); 217 } 218 219 if (!prev) 220 goto out; 221 222 if (local_rcv) 223 deliver_clone(prev, skb, local_orig); 224 else 225 __br_forward(prev, skb, local_orig); 226 return; 227 228 out: 229 if (!local_rcv) 230 kfree_skb(skb); 231 } 232 233 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING 234 static void maybe_deliver_addr(struct net_bridge_port *p, struct sk_buff *skb, 235 const unsigned char *addr, bool local_orig) 236 { 237 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 238 const unsigned char *src = eth_hdr(skb)->h_source; 239 240 if (!should_deliver(p, skb)) 241 return; 242 243 /* Even with hairpin, no soliloquies - prevent breaking IPv6 DAD */ 244 if (skb->dev == p->dev && ether_addr_equal(src, addr)) 245 return; 246 247 skb = skb_copy(skb, GFP_ATOMIC); 248 if (!skb) { 249 dev->stats.tx_dropped++; 250 return; 251 } 252 253 if (!is_broadcast_ether_addr(addr)) 254 memcpy(eth_hdr(skb)->h_dest, addr, ETH_ALEN); 255 256 __br_forward(p, skb, local_orig); 257 } 258 259 /* called with rcu_read_lock */ 260 void br_multicast_flood(struct net_bridge_mdb_entry *mdst, 261 struct sk_buff *skb, 262 bool local_rcv, bool local_orig) 263 { 264 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 265 u8 igmp_type = br_multicast_igmp_type(skb); 266 struct net_bridge *br = netdev_priv(dev); 267 struct net_bridge_port *prev = NULL; 268 struct net_bridge_port_group *p; 269 struct hlist_node *rp; 270 271 rp = rcu_dereference(hlist_first_rcu(&br->router_list)); 272 p = mdst ? rcu_dereference(mdst->ports) : NULL; 273 while (p || rp) { 274 struct net_bridge_port *port, *lport, *rport; 275 276 lport = p ? p->port : NULL; 277 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) : 278 NULL; 279 280 if ((unsigned long)lport > (unsigned long)rport) { 281 port = lport; 282 283 if (port->flags & BR_MULTICAST_TO_UNICAST) { 284 maybe_deliver_addr(lport, skb, p->eth_addr, 285 local_orig); 286 goto delivered; 287 } 288 } else { 289 port = rport; 290 } 291 292 prev = maybe_deliver(prev, port, skb, local_orig); 293 delivered: 294 if (IS_ERR(prev)) 295 goto out; 296 if (prev == port) 297 br_multicast_count(port->br, port, skb, igmp_type, 298 BR_MCAST_DIR_TX); 299 300 if ((unsigned long)lport >= (unsigned long)port) 301 p = rcu_dereference(p->next); 302 if ((unsigned long)rport >= (unsigned long)port) 303 rp = rcu_dereference(hlist_next_rcu(rp)); 304 } 305 306 if (!prev) 307 goto out; 308 309 if (local_rcv) 310 deliver_clone(prev, skb, local_orig); 311 else 312 __br_forward(prev, skb, local_orig); 313 return; 314 315 out: 316 if (!local_rcv) 317 kfree_skb(skb); 318 } 319 #endif 320