net/bridge/br_forward.c

   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         skb_push(skb, ETH_HLEN);
  39         if (!is_skb_forwardable(skb->dev, skb))
  40                 goto drop;
  41
  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                         skb_push(skb, ETH_HLEN);
 100                         if (!is_skb_forwardable(skb->dev, skb))
 101                                 kfree_skb(skb);
 102                         else
 103                                 br_netpoll_send_skb(to, skb);
 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               enum br_pkt_type pkt_type, 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, nor
 186                  * other traffic if flood off, except for traffic we originate
 187                  */
 188                 switch (pkt_type) {
 189                 case BR_PKT_UNICAST:
 190                         if (!(p->flags & BR_FLOOD))
 191                                 continue;
 192                         break;
 193                 case BR_PKT_MULTICAST:
 194                         if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev)
 195                                 continue;
 196                         break;
 197                 case BR_PKT_BROADCAST:
 198                         if (!(p->flags & BR_BCAST_FLOOD) && skb->dev != br->dev)
 199                                 continue;
 200                         break;
 201                 }
 202
 203                 /* Do not flood to ports that enable proxy ARP */
 204                 if (p->flags & BR_PROXYARP)
 205                         continue;
 206                 if ((p->flags & BR_PROXYARP_WIFI) &&
 207                     BR_INPUT_SKB_CB(skb)->proxyarp_replied)
 208                         continue;
 209
 210                 prev = maybe_deliver(prev, p, skb, local_orig);
 211                 if (IS_ERR(prev))
 212                         goto out;
 213                 if (prev == p)
 214                         br_multicast_count(p->br, p, skb, igmp_type,
 215                                            BR_MCAST_DIR_TX);
 216         }
 217
 218         if (!prev)
 219                 goto out;
 220
 221         if (local_rcv)
 222                 deliver_clone(prev, skb, local_orig);
 223         else
 224                 __br_forward(prev, skb, local_orig);
 225         return;
 226
 227 out:
 228         if (!local_rcv)
 229                 kfree_skb(skb);
 230 }
 231
 232 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 233 static void maybe_deliver_addr(struct net_bridge_port *p, struct sk_buff *skb,
 234                                const unsigned char *addr, bool local_orig)
 235 {
 236         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 237         const unsigned char *src = eth_hdr(skb)->h_source;
 238
 239         if (!should_deliver(p, skb))
 240                 return;
 241
 242         /* Even with hairpin, no soliloquies - prevent breaking IPv6 DAD */
 243         if (skb->dev == p->dev && ether_addr_equal(src, addr))
 244                 return;
 245
 246         skb = skb_copy(skb, GFP_ATOMIC);
 247         if (!skb) {
 248                 dev->stats.tx_dropped++;
 249                 return;
 250         }
 251
 252         if (!is_broadcast_ether_addr(addr))
 253                 memcpy(eth_hdr(skb)->h_dest, addr, ETH_ALEN);
 254
 255         __br_forward(p, skb, local_orig);
 256 }
 257
 258 /* called with rcu_read_lock */
 259 void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 260                         struct sk_buff *skb,
 261                         bool local_rcv, bool local_orig)
 262 {
 263         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 264         u8 igmp_type = br_multicast_igmp_type(skb);
 265         struct net_bridge *br = netdev_priv(dev);
 266         struct net_bridge_port *prev = NULL;
 267         struct net_bridge_port_group *p;
 268         struct hlist_node *rp;
 269
 270         rp = rcu_dereference(hlist_first_rcu(&br->router_list));
 271         p = mdst ? rcu_dereference(mdst->ports) : NULL;
 272         while (p || rp) {
 273                 struct net_bridge_port *port, *lport, *rport;
 274
 275                 lport = p ? p->port : NULL;
 276                 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
 277                              NULL;
 278
 279                 if ((unsigned long)lport > (unsigned long)rport) {
 280                         port = lport;
 281
 282                         if (port->flags & BR_MULTICAST_TO_UNICAST) {
 283                                 maybe_deliver_addr(lport, skb, p->eth_addr,
 284                                                    local_orig);
 285                                 goto delivered;
 286                         }
 287                 } else {
 288                         port = rport;
 289                 }
 290
 291                 prev = maybe_deliver(prev, port, skb, local_orig);
 292 delivered:
 293                 if (IS_ERR(prev))
 294                         goto out;
 295                 if (prev == port)
 296                         br_multicast_count(port->br, port, skb, igmp_type,
 297                                            BR_MCAST_DIR_TX);
 298
 299                 if ((unsigned long)lport >= (unsigned long)port)
 300                         p = rcu_dereference(p->next);
 301                 if ((unsigned long)rport >= (unsigned long)port)
 302                         rp = rcu_dereference(hlist_next_rcu(rp));
 303         }
 304
 305         if (!prev)
 306                 goto out;
 307
 308         if (local_rcv)
 309                 deliver_clone(prev, skb, local_orig);
 310         else
 311                 __br_forward(prev, skb, local_orig);
 312         return;
 313
 314 out:
 315         if (!local_rcv)
 316                 kfree_skb(skb);
 317 }
 318 #endif