| 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 | } |
| 34 | |
| 35 | int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb) |
| 36 | { |
| 37 | if (!is_skb_forwardable(skb->dev, skb)) |
| 38 | goto drop; |
| 39 | |
| 40 | skb_push(skb, ETH_HLEN); |
| 41 | br_drop_fake_rtable(skb); |
| 42 | |
| 43 | if (skb->ip_summed == CHECKSUM_PARTIAL && |
| 44 | (skb->protocol == htons(ETH_P_8021Q) || |
| 45 | skb->protocol == htons(ETH_P_8021AD))) { |
| 46 | int depth; |
| 47 | |
| 48 | if (!__vlan_get_protocol(skb, skb->protocol, &depth)) |
| 49 | goto drop; |
| 50 | |
| 51 | skb_set_network_header(skb, depth); |
| 52 | } |
| 53 | |
| 54 | dev_queue_xmit(skb); |
| 55 | |
| 56 | return 0; |
| 57 | |
| 58 | drop: |
| 59 | kfree_skb(skb); |
| 60 | return 0; |
| 61 | } |
| 62 | EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit); |
| 63 | |
| 64 | int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb) |
| 65 | { |
| 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 | vg = nbp_vlan_group_rcu(to); |
| 82 | skb = br_handle_vlan(to->br, vg, skb); |
| 83 | if (!skb) |
| 84 | return; |
| 85 | |
| 86 | indev = skb->dev; |
| 87 | skb->dev = to->dev; |
| 88 | if (!local_orig) { |
| 89 | if (skb_warn_if_lro(skb)) { |
| 90 | kfree_skb(skb); |
| 91 | return; |
| 92 | } |
| 93 | br_hook = NF_BR_FORWARD; |
| 94 | skb_forward_csum(skb); |
| 95 | net = dev_net(indev); |
| 96 | } else { |
| 97 | if (unlikely(netpoll_tx_running(to->br->dev))) { |
| 98 | if (!is_skb_forwardable(skb->dev, skb)) { |
| 99 | kfree_skb(skb); |
| 100 | } else { |
| 101 | skb_push(skb, ETH_HLEN); |
| 102 | br_netpoll_send_skb(to, skb); |
| 103 | } |
| 104 | return; |
| 105 | } |
| 106 | br_hook = NF_BR_LOCAL_OUT; |
| 107 | net = dev_net(skb->dev); |
| 108 | indev = NULL; |
| 109 | } |
| 110 | |
| 111 | NF_HOOK(NFPROTO_BRIDGE, br_hook, |
| 112 | net, NULL, skb, indev, skb->dev, |
| 113 | br_forward_finish); |
| 114 | } |
| 115 | |
| 116 | static int deliver_clone(const struct net_bridge_port *prev, |
| 117 | struct sk_buff *skb, bool local_orig) |
| 118 | { |
| 119 | struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; |
| 120 | |
| 121 | skb = skb_clone(skb, GFP_ATOMIC); |
| 122 | if (!skb) { |
| 123 | dev->stats.tx_dropped++; |
| 124 | return -ENOMEM; |
| 125 | } |
| 126 | |
| 127 | __br_forward(prev, skb, local_orig); |
| 128 | return 0; |
| 129 | } |
| 130 | |
| 131 | /** |
| 132 | * br_forward - forward a packet to a specific port |
| 133 | * @to: destination port |
| 134 | * @skb: packet being forwarded |
| 135 | * @local_rcv: packet will be received locally after forwarding |
| 136 | * @local_orig: packet is locally originated |
| 137 | * |
| 138 | * Should be called with rcu_read_lock. |
| 139 | */ |
| 140 | void br_forward(const struct net_bridge_port *to, |
| 141 | struct sk_buff *skb, bool local_rcv, bool local_orig) |
| 142 | { |
| 143 | if (to && should_deliver(to, skb)) { |
| 144 | if (local_rcv) |
| 145 | deliver_clone(to, skb, local_orig); |
| 146 | else |
| 147 | __br_forward(to, skb, local_orig); |
| 148 | return; |
| 149 | } |
| 150 | |
| 151 | if (!local_rcv) |
| 152 | kfree_skb(skb); |
| 153 | } |
| 154 | EXPORT_SYMBOL_GPL(br_forward); |
| 155 | |
| 156 | static struct net_bridge_port *maybe_deliver( |
| 157 | struct net_bridge_port *prev, struct net_bridge_port *p, |
| 158 | struct sk_buff *skb, bool local_orig) |
| 159 | { |
| 160 | int err; |
| 161 | |
| 162 | if (!should_deliver(p, skb)) |
| 163 | return prev; |
| 164 | |
| 165 | if (!prev) |
| 166 | goto out; |
| 167 | |
| 168 | err = deliver_clone(prev, skb, local_orig); |
| 169 | if (err) |
| 170 | return ERR_PTR(err); |
| 171 | |
| 172 | out: |
| 173 | return p; |
| 174 | } |
| 175 | |
| 176 | /* called under rcu_read_lock */ |
| 177 | void br_flood(struct net_bridge *br, struct sk_buff *skb, |
| 178 | bool unicast, bool local_rcv, bool local_orig) |
| 179 | { |
| 180 | u8 igmp_type = br_multicast_igmp_type(skb); |
| 181 | struct net_bridge_port *prev = NULL; |
| 182 | struct net_bridge_port *p; |
| 183 | |
| 184 | list_for_each_entry_rcu(p, &br->port_list, list) { |
| 185 | /* Do not flood unicast traffic to ports that turn it off */ |
| 186 | if (unicast && !(p->flags & BR_FLOOD)) |
| 187 | continue; |
| 188 | |
| 189 | /* Do not flood to ports that enable proxy ARP */ |
| 190 | if (p->flags & BR_PROXYARP) |
| 191 | continue; |
| 192 | if ((p->flags & BR_PROXYARP_WIFI) && |
| 193 | BR_INPUT_SKB_CB(skb)->proxyarp_replied) |
| 194 | continue; |
| 195 | |
| 196 | prev = maybe_deliver(prev, p, skb, local_orig); |
| 197 | if (IS_ERR(prev)) |
| 198 | goto out; |
| 199 | if (prev == p) |
| 200 | br_multicast_count(p->br, p, skb, igmp_type, |
| 201 | BR_MCAST_DIR_TX); |
| 202 | } |
| 203 | |
| 204 | if (!prev) |
| 205 | goto out; |
| 206 | |
| 207 | if (local_rcv) |
| 208 | deliver_clone(prev, skb, local_orig); |
| 209 | else |
| 210 | __br_forward(prev, skb, local_orig); |
| 211 | return; |
| 212 | |
| 213 | out: |
| 214 | if (!local_rcv) |
| 215 | kfree_skb(skb); |
| 216 | } |
| 217 | |
| 218 | #ifdef CONFIG_BRIDGE_IGMP_SNOOPING |
| 219 | /* called with rcu_read_lock */ |
| 220 | void br_multicast_flood(struct net_bridge_mdb_entry *mdst, |
| 221 | struct sk_buff *skb, |
| 222 | bool local_rcv, bool local_orig) |
| 223 | { |
| 224 | struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev; |
| 225 | u8 igmp_type = br_multicast_igmp_type(skb); |
| 226 | struct net_bridge *br = netdev_priv(dev); |
| 227 | struct net_bridge_port *prev = NULL; |
| 228 | struct net_bridge_port_group *p; |
| 229 | struct hlist_node *rp; |
| 230 | |
| 231 | rp = rcu_dereference(hlist_first_rcu(&br->router_list)); |
| 232 | p = mdst ? rcu_dereference(mdst->ports) : NULL; |
| 233 | while (p || rp) { |
| 234 | struct net_bridge_port *port, *lport, *rport; |
| 235 | |
| 236 | lport = p ? p->port : NULL; |
| 237 | rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) : |
| 238 | NULL; |
| 239 | |
| 240 | port = (unsigned long)lport > (unsigned long)rport ? |
| 241 | lport : rport; |
| 242 | |
| 243 | prev = maybe_deliver(prev, port, skb, local_orig); |
| 244 | if (IS_ERR(prev)) |
| 245 | goto out; |
| 246 | if (prev == port) |
| 247 | br_multicast_count(port->br, port, skb, igmp_type, |
| 248 | BR_MCAST_DIR_TX); |
| 249 | |
| 250 | if ((unsigned long)lport >= (unsigned long)port) |
| 251 | p = rcu_dereference(p->next); |
| 252 | if ((unsigned long)rport >= (unsigned long)port) |
| 253 | rp = rcu_dereference(hlist_next_rcu(rp)); |
| 254 | } |
| 255 | |
| 256 | if (!prev) |
| 257 | goto out; |
| 258 | |
| 259 | if (local_rcv) |
| 260 | deliver_clone(prev, skb, local_orig); |
| 261 | else |
| 262 | __br_forward(prev, skb, local_orig); |
| 263 | return; |
| 264 | |
| 265 | out: |
| 266 | if (!local_rcv) |
| 267 | kfree_skb(skb); |
| 268 | } |
| 269 | #endif |