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Linux/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         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, 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 */
187                 if (pkt_type == BR_PKT_UNICAST && !(p->flags & BR_FLOOD))
188                         continue;
189                 if (pkt_type == BR_PKT_MULTICAST &&
190                     !(p->flags & BR_MCAST_FLOOD))
191                         continue;
192 
193                 /* Do not flood to ports that enable proxy ARP */
194                 if (p->flags & BR_PROXYARP)
195                         continue;
196                 if ((p->flags & BR_PROXYARP_WIFI) &&
197                     BR_INPUT_SKB_CB(skb)->proxyarp_replied)
198                         continue;
199 
200                 prev = maybe_deliver(prev, p, skb, local_orig);
201                 if (IS_ERR(prev))
202                         goto out;
203                 if (prev == p)
204                         br_multicast_count(p->br, p, skb, igmp_type,
205                                            BR_MCAST_DIR_TX);
206         }
207 
208         if (!prev)
209                 goto out;
210 
211         if (local_rcv)
212                 deliver_clone(prev, skb, local_orig);
213         else
214                 __br_forward(prev, skb, local_orig);
215         return;
216 
217 out:
218         if (!local_rcv)
219                 kfree_skb(skb);
220 }
221 
222 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
223 /* called with rcu_read_lock */
224 void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
225                         struct sk_buff *skb,
226                         bool local_rcv, bool local_orig)
227 {
228         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
229         u8 igmp_type = br_multicast_igmp_type(skb);
230         struct net_bridge *br = netdev_priv(dev);
231         struct net_bridge_port *prev = NULL;
232         struct net_bridge_port_group *p;
233         struct hlist_node *rp;
234 
235         rp = rcu_dereference(hlist_first_rcu(&br->router_list));
236         p = mdst ? rcu_dereference(mdst->ports) : NULL;
237         while (p || rp) {
238                 struct net_bridge_port *port, *lport, *rport;
239 
240                 lport = p ? p->port : NULL;
241                 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
242                              NULL;
243 
244                 port = (unsigned long)lport > (unsigned long)rport ?
245                        lport : rport;
246 
247                 prev = maybe_deliver(prev, port, skb, local_orig);
248                 if (IS_ERR(prev))
249                         goto out;
250                 if (prev == port)
251                         br_multicast_count(port->br, port, skb, igmp_type,
252                                            BR_MCAST_DIR_TX);
253 
254                 if ((unsigned long)lport >= (unsigned long)port)
255                         p = rcu_dereference(p->next);
256                 if ((unsigned long)rport >= (unsigned long)port)
257                         rp = rcu_dereference(hlist_next_rcu(rp));
258         }
259 
260         if (!prev)
261                 goto out;
262 
263         if (local_rcv)
264                 deliver_clone(prev, skb, local_orig);
265         else
266                 __br_forward(prev, skb, local_orig);
267         return;
268 
269 out:
270         if (!local_rcv)
271                 kfree_skb(skb);
272 }
273 #endif
274 

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