1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Forwarding decision 4 * Linux ethernet bridge 5 * 6 * Authors: 7 * Lennert Buytenhek <buytenh@gnu.org> 8 */ 9 10 #include <linux/err.h> 11 #include <linux/slab.h> 12 #include <linux/kernel.h> 13 #include <linux/netdevice.h> 14 #include <linux/netpoll.h> 15 #include <linux/skbuff.h> 16 #include <linux/if_vlan.h> 17 #include <linux/netfilter_bridge.h> 18 #include "br_private.h" 19 20 /* Don't forward packets to originating port or forwarding disabled */ 21 static inline int should_deliver(const struct net_bridge_port *p, 22 const struct sk_buff *skb) 23 { 24 struct net_bridge_vlan_group *vg; 25 26 vg = nbp_vlan_group_rcu(p); 27 return ((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) && 28 p->state == BR_STATE_FORWARDING && br_allowed_egress(vg, skb) && 29 nbp_switchdev_allowed_egress(p, skb) && 30 !br_skb_isolated(p, skb); 31 } 32 33 int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb) 34 { 35 skb_push(skb, ETH_HLEN); 36 if (!is_skb_forwardable(skb->dev, skb)) 37 goto drop; 38 39 br_drop_fake_rtable(skb); 40 41 if (skb->ip_summed == CHECKSUM_PARTIAL && 42 eth_type_vlan(skb->protocol)) { 43 int depth; 44 45 if (!__vlan_get_protocol(skb, skb->protocol, &depth)) 46 goto drop; 47 48 skb_set_network_header(skb, depth); 49 } 50 51 dev_queue_xmit(skb); 52 53 return 0; 54 55 drop: 56 kfree_skb(skb); 57 return 0; 58 } 59 EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit); 60 61 int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 62 { 63 skb->tstamp = 0; 64 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, 65 net, sk, skb, NULL, skb->dev, 66 br_dev_queue_push_xmit); 67 68 } 69 EXPORT_SYMBOL_GPL(br_forward_finish); 70 71 static void __br_forward(const struct net_bridge_port *to, 72 struct sk_buff *skb, bool local_orig) 73 { 74 struct net_bridge_vlan_group *vg; 75 struct net_device *indev; 76 struct net *net; 77 int br_hook; 78 79 vg = nbp_vlan_group_rcu(to); 80 skb = br_handle_vlan(to->br, to, vg, skb); 81 if (!skb) 82 return; 83 84 indev = skb->dev; 85 skb->dev = to->dev; 86 if (!local_orig) { 87 if (skb_warn_if_lro(skb)) { 88 kfree_skb(skb); 89 return; 90 } 91 br_hook = NF_BR_FORWARD; 92 skb_forward_csum(skb); 93 net = dev_net(indev); 94 } else { 95 if (unlikely(netpoll_tx_running(to->br->dev))) { 96 skb_push(skb, ETH_HLEN); 97 if (!is_skb_forwardable(skb->dev, skb)) 98 kfree_skb(skb); 99 else 100 br_netpoll_send_skb(to, skb); 101 return; 102 } 103 br_hook = NF_BR_LOCAL_OUT; 104 net = dev_net(skb->dev); 105 indev = NULL; 106 } 107 108 NF_HOOK(NFPROTO_BRIDGE, br_hook, 109 net, NULL, skb, indev, skb->dev, 110 br_forward_finish); 111 } 112 113 static int deliver_clone(const struct net_bridge_port *prev, 114 struct sk_buff *skb, bool local_orig) 115 { 116 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 117 118 skb = skb_clone(skb, GFP_ATOMIC); 119 if (!skb) { 120 dev->stats.tx_dropped++; 121 return -ENOMEM; 122 } 123 124 __br_forward(prev, skb, local_orig); 125 return 0; 126 } 127 128 /** 129 * br_forward - forward a packet to a specific port 130 * @to: destination port 131 * @skb: packet being forwarded 132 * @local_rcv: packet will be received locally after forwarding 133 * @local_orig: packet is locally originated 134 * 135 * Should be called with rcu_read_lock. 136 */ 137 void br_forward(const struct net_bridge_port *to, 138 struct sk_buff *skb, bool local_rcv, bool local_orig) 139 { 140 if (unlikely(!to)) 141 goto out; 142 143 /* redirect to backup link if the destination port is down */ 144 if (rcu_access_pointer(to->backup_port) && !netif_carrier_ok(to->dev)) { 145 struct net_bridge_port *backup_port; 146 147 backup_port = rcu_dereference(to->backup_port); 148 if (unlikely(!backup_port)) 149 goto out; 150 to = backup_port; 151 } 152 153 if (should_deliver(to, skb)) { 154 if (local_rcv) 155 deliver_clone(to, skb, local_orig); 156 else 157 __br_forward(to, skb, local_orig); 158 return; 159 } 160 161 out: 162 if (!local_rcv) 163 kfree_skb(skb); 164 } 165 EXPORT_SYMBOL_GPL(br_forward); 166 167 static struct net_bridge_port *maybe_deliver( 168 struct net_bridge_port *prev, struct net_bridge_port *p, 169 struct sk_buff *skb, bool local_orig) 170 { 171 u8 igmp_type = br_multicast_igmp_type(skb); 172 int err; 173 174 if (!should_deliver(p, skb)) 175 return prev; 176 177 if (!prev) 178 goto out; 179 180 err = deliver_clone(prev, skb, local_orig); 181 if (err) 182 return ERR_PTR(err); 183 out: 184 br_multicast_count(p->br, p, skb, igmp_type, BR_MCAST_DIR_TX); 185 186 return p; 187 } 188 189 /* called under rcu_read_lock */ 190 void br_flood(struct net_bridge *br, struct sk_buff *skb, 191 enum br_pkt_type pkt_type, bool local_rcv, bool local_orig) 192 { 193 struct net_bridge_port *prev = NULL; 194 struct net_bridge_port *p; 195 196 list_for_each_entry_rcu(p, &br->port_list, list) { 197 /* Do not flood unicast traffic to ports that turn it off, nor 198 * other traffic if flood off, except for traffic we originate 199 */ 200 switch (pkt_type) { 201 case BR_PKT_UNICAST: 202 if (!(p->flags & BR_FLOOD)) 203 continue; 204 break; 205 case BR_PKT_MULTICAST: 206 if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev) 207 continue; 208 break; 209 case BR_PKT_BROADCAST: 210 if (!(p->flags & BR_BCAST_FLOOD) && skb->dev != br->dev) 211 continue; 212 break; 213 } 214 215 /* Do not flood to ports that enable proxy ARP */ 216 if (p->flags & BR_PROXYARP) 217 continue; 218 if ((p->flags & (BR_PROXYARP_WIFI | BR_NEIGH_SUPPRESS)) && 219 BR_INPUT_SKB_CB(skb)->proxyarp_replied) 220 continue; 221 222 prev = maybe_deliver(prev, p, skb, local_orig); 223 if (IS_ERR(prev)) 224 goto out; 225 } 226 227 if (!prev) 228 goto out; 229 230 if (local_rcv) 231 deliver_clone(prev, skb, local_orig); 232 else 233 __br_forward(prev, skb, local_orig); 234 return; 235 236 out: 237 if (!local_rcv) 238 kfree_skb(skb); 239 } 240 241 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING 242 static void maybe_deliver_addr(struct net_bridge_port *p, struct sk_buff *skb, 243 const unsigned char *addr, bool local_orig) 244 { 245 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 246 const unsigned char *src = eth_hdr(skb)->h_source; 247 248 if (!should_deliver(p, skb)) 249 return; 250 251 /* Even with hairpin, no soliloquies - prevent breaking IPv6 DAD */ 252 if (skb->dev == p->dev && ether_addr_equal(src, addr)) 253 return; 254 255 skb = skb_copy(skb, GFP_ATOMIC); 256 if (!skb) { 257 dev->stats.tx_dropped++; 258 return; 259 } 260 261 if (!is_broadcast_ether_addr(addr)) 262 memcpy(eth_hdr(skb)->h_dest, addr, ETH_ALEN); 263 264 __br_forward(p, skb, local_orig); 265 } 266 267 /* called with rcu_read_lock */ 268 void br_multicast_flood(struct net_bridge_mdb_entry *mdst, 269 struct sk_buff *skb, 270 bool local_rcv, bool local_orig) 271 { 272 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 273 struct net_bridge *br = netdev_priv(dev); 274 struct net_bridge_port *prev = NULL; 275 struct net_bridge_port_group *p; 276 bool allow_mode_include = true; 277 struct hlist_node *rp; 278 279 rp = br_multicast_get_first_rport_node(br, skb); 280 281 if (mdst) { 282 p = rcu_dereference(mdst->ports); 283 if (br_multicast_should_handle_mode(br, mdst->addr.proto) && 284 br_multicast_is_star_g(&mdst->addr)) 285 allow_mode_include = false; 286 } else { 287 p = NULL; 288 } 289 290 while (p || rp) { 291 struct net_bridge_port *port, *lport, *rport; 292 293 lport = p ? p->key.port : NULL; 294 rport = br_multicast_rport_from_node_skb(rp, skb); 295 296 if ((unsigned long)lport > (unsigned long)rport) { 297 port = lport; 298 299 if (port->flags & BR_MULTICAST_TO_UNICAST) { 300 maybe_deliver_addr(lport, skb, p->eth_addr, 301 local_orig); 302 goto delivered; 303 } 304 if ((!allow_mode_include && 305 p->filter_mode == MCAST_INCLUDE) || 306 (p->flags & MDB_PG_FLAGS_BLOCKED)) 307 goto delivered; 308 } else { 309 port = rport; 310 } 311 312 prev = maybe_deliver(prev, port, skb, local_orig); 313 if (IS_ERR(prev)) 314 goto out; 315 delivered: 316 if ((unsigned long)lport >= (unsigned long)port) 317 p = rcu_dereference(p->next); 318 if ((unsigned long)rport >= (unsigned long)port) 319 rp = rcu_dereference(hlist_next_rcu(rp)); 320 } 321 322 if (!prev) 323 goto out; 324 325 if (local_rcv) 326 deliver_clone(prev, skb, local_orig); 327 else 328 __br_forward(prev, skb, local_orig); 329 return; 330 331 out: 332 if (!local_rcv) 333 kfree_skb(skb); 334 } 335 #endif 336