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 br_switchdev_frame_set_offload_fwd_mark(skb); 52 53 dev_queue_xmit(skb); 54 55 return 0; 56 57 drop: 58 kfree_skb(skb); 59 return 0; 60 } 61 EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit); 62 63 int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 64 { 65 skb_clear_tstamp(skb); 66 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, 67 net, sk, skb, NULL, skb->dev, 68 br_dev_queue_push_xmit); 69 70 } 71 EXPORT_SYMBOL_GPL(br_forward_finish); 72 73 static void __br_forward(const struct net_bridge_port *to, 74 struct sk_buff *skb, bool local_orig) 75 { 76 struct net_bridge_vlan_group *vg; 77 struct net_device *indev; 78 struct net *net; 79 int br_hook; 80 81 /* Mark the skb for forwarding offload early so that br_handle_vlan() 82 * can know whether to pop the VLAN header on egress or keep it. 83 */ 84 nbp_switchdev_frame_mark_tx_fwd_offload(to, skb); 85 86 vg = nbp_vlan_group_rcu(to); 87 skb = br_handle_vlan(to->br, to, vg, skb); 88 if (!skb) 89 return; 90 91 indev = skb->dev; 92 skb->dev = to->dev; 93 if (!local_orig) { 94 if (skb_warn_if_lro(skb)) { 95 kfree_skb(skb); 96 return; 97 } 98 br_hook = NF_BR_FORWARD; 99 skb_forward_csum(skb); 100 net = dev_net(indev); 101 } else { 102 if (unlikely(netpoll_tx_running(to->br->dev))) { 103 skb_push(skb, ETH_HLEN); 104 if (!is_skb_forwardable(skb->dev, skb)) 105 kfree_skb(skb); 106 else 107 br_netpoll_send_skb(to, skb); 108 return; 109 } 110 br_hook = NF_BR_LOCAL_OUT; 111 net = dev_net(skb->dev); 112 indev = NULL; 113 } 114 115 NF_HOOK(NFPROTO_BRIDGE, br_hook, 116 net, NULL, skb, indev, skb->dev, 117 br_forward_finish); 118 } 119 120 static int deliver_clone(const struct net_bridge_port *prev, 121 struct sk_buff *skb, bool local_orig) 122 { 123 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 124 125 skb = skb_clone(skb, GFP_ATOMIC); 126 if (!skb) { 127 dev->stats.tx_dropped++; 128 return -ENOMEM; 129 } 130 131 __br_forward(prev, skb, local_orig); 132 return 0; 133 } 134 135 /** 136 * br_forward - forward a packet to a specific port 137 * @to: destination port 138 * @skb: packet being forwarded 139 * @local_rcv: packet will be received locally after forwarding 140 * @local_orig: packet is locally originated 141 * 142 * Should be called with rcu_read_lock. 143 */ 144 void br_forward(const struct net_bridge_port *to, 145 struct sk_buff *skb, bool local_rcv, bool local_orig) 146 { 147 if (unlikely(!to)) 148 goto out; 149 150 /* redirect to backup link if the destination port is down */ 151 if (rcu_access_pointer(to->backup_port) && !netif_carrier_ok(to->dev)) { 152 struct net_bridge_port *backup_port; 153 154 backup_port = rcu_dereference(to->backup_port); 155 if (unlikely(!backup_port)) 156 goto out; 157 to = backup_port; 158 } 159 160 if (should_deliver(to, skb)) { 161 if (local_rcv) 162 deliver_clone(to, skb, local_orig); 163 else 164 __br_forward(to, skb, local_orig); 165 return; 166 } 167 168 out: 169 if (!local_rcv) 170 kfree_skb(skb); 171 } 172 EXPORT_SYMBOL_GPL(br_forward); 173 174 static struct net_bridge_port *maybe_deliver( 175 struct net_bridge_port *prev, struct net_bridge_port *p, 176 struct sk_buff *skb, bool local_orig) 177 { 178 u8 igmp_type = br_multicast_igmp_type(skb); 179 int err; 180 181 if (!should_deliver(p, skb)) 182 return prev; 183 184 nbp_switchdev_frame_mark_tx_fwd_to_hwdom(p, skb); 185 186 if (!prev) 187 goto out; 188 189 err = deliver_clone(prev, skb, local_orig); 190 if (err) 191 return ERR_PTR(err); 192 out: 193 br_multicast_count(p->br, p, skb, igmp_type, BR_MCAST_DIR_TX); 194 195 return p; 196 } 197 198 /* called under rcu_read_lock */ 199 void br_flood(struct net_bridge *br, struct sk_buff *skb, 200 enum br_pkt_type pkt_type, bool local_rcv, bool local_orig) 201 { 202 struct net_bridge_port *prev = NULL; 203 struct net_bridge_port *p; 204 205 list_for_each_entry_rcu(p, &br->port_list, list) { 206 /* Do not flood unicast traffic to ports that turn it off, nor 207 * other traffic if flood off, except for traffic we originate 208 */ 209 switch (pkt_type) { 210 case BR_PKT_UNICAST: 211 if (!(p->flags & BR_FLOOD)) 212 continue; 213 break; 214 case BR_PKT_MULTICAST: 215 if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev) 216 continue; 217 break; 218 case BR_PKT_BROADCAST: 219 if (!(p->flags & BR_BCAST_FLOOD) && skb->dev != br->dev) 220 continue; 221 break; 222 } 223 224 /* Do not flood to ports that enable proxy ARP */ 225 if (p->flags & BR_PROXYARP) 226 continue; 227 if ((p->flags & (BR_PROXYARP_WIFI | BR_NEIGH_SUPPRESS)) && 228 BR_INPUT_SKB_CB(skb)->proxyarp_replied) 229 continue; 230 231 prev = maybe_deliver(prev, p, skb, local_orig); 232 if (IS_ERR(prev)) 233 goto out; 234 } 235 236 if (!prev) 237 goto out; 238 239 if (local_rcv) 240 deliver_clone(prev, skb, local_orig); 241 else 242 __br_forward(prev, skb, local_orig); 243 return; 244 245 out: 246 if (!local_rcv) 247 kfree_skb(skb); 248 } 249 250 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING 251 static void maybe_deliver_addr(struct net_bridge_port *p, struct sk_buff *skb, 252 const unsigned char *addr, bool local_orig) 253 { 254 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; 255 const unsigned char *src = eth_hdr(skb)->h_source; 256 257 if (!should_deliver(p, skb)) 258 return; 259 260 /* Even with hairpin, no soliloquies - prevent breaking IPv6 DAD */ 261 if (skb->dev == p->dev && ether_addr_equal(src, addr)) 262 return; 263 264 skb = skb_copy(skb, GFP_ATOMIC); 265 if (!skb) { 266 dev->stats.tx_dropped++; 267 return; 268 } 269 270 if (!is_broadcast_ether_addr(addr)) 271 memcpy(eth_hdr(skb)->h_dest, addr, ETH_ALEN); 272 273 __br_forward(p, skb, local_orig); 274 } 275 276 /* called with rcu_read_lock */ 277 void br_multicast_flood(struct net_bridge_mdb_entry *mdst, 278 struct sk_buff *skb, 279 struct net_bridge_mcast *brmctx, 280 bool local_rcv, bool local_orig) 281 { 282 struct net_bridge_port *prev = NULL; 283 struct net_bridge_port_group *p; 284 bool allow_mode_include = true; 285 struct hlist_node *rp; 286 287 rp = br_multicast_get_first_rport_node(brmctx, skb); 288 289 if (mdst) { 290 p = rcu_dereference(mdst->ports); 291 if (br_multicast_should_handle_mode(brmctx, mdst->addr.proto) && 292 br_multicast_is_star_g(&mdst->addr)) 293 allow_mode_include = false; 294 } else { 295 p = NULL; 296 } 297 298 while (p || rp) { 299 struct net_bridge_port *port, *lport, *rport; 300 301 lport = p ? p->key.port : NULL; 302 rport = br_multicast_rport_from_node_skb(rp, skb); 303 304 if ((unsigned long)lport > (unsigned long)rport) { 305 port = lport; 306 307 if (port->flags & BR_MULTICAST_TO_UNICAST) { 308 maybe_deliver_addr(lport, skb, p->eth_addr, 309 local_orig); 310 goto delivered; 311 } 312 if ((!allow_mode_include && 313 p->filter_mode == MCAST_INCLUDE) || 314 (p->flags & MDB_PG_FLAGS_BLOCKED)) 315 goto delivered; 316 } else { 317 port = rport; 318 } 319 320 prev = maybe_deliver(prev, port, skb, local_orig); 321 if (IS_ERR(prev)) 322 goto out; 323 delivered: 324 if ((unsigned long)lport >= (unsigned long)port) 325 p = rcu_dereference(p->next); 326 if ((unsigned long)rport >= (unsigned long)port) 327 rp = rcu_dereference(hlist_next_rcu(rp)); 328 } 329 330 if (!prev) 331 goto out; 332 333 if (local_rcv) 334 deliver_clone(prev, skb, local_orig); 335 else 336 __br_forward(prev, skb, local_orig); 337 return; 338 339 out: 340 if (!local_rcv) 341 kfree_skb(skb); 342 } 343 #endif 344