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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 static int deliver_clone(const struct net_bridge_port *prev,
 25                          struct sk_buff *skb,
 26                          void (*__packet_hook)(const struct net_bridge_port *p,
 27                                                struct sk_buff *skb));
 28 
 29 /* Don't forward packets to originating port or forwarding disabled */
 30 static inline int should_deliver(const struct net_bridge_port *p,
 31                                  const struct sk_buff *skb)
 32 {
 33         return ((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
 34                 br_allowed_egress(p->br, nbp_get_vlan_info(p), skb) &&
 35                 p->state == BR_STATE_FORWARDING;
 36 }
 37 
 38 int br_dev_queue_push_xmit(struct sk_buff *skb)
 39 {
 40         /* ip_fragment doesn't copy the MAC header */
 41         if (nf_bridge_maybe_copy_header(skb) ||
 42             !is_skb_forwardable(skb->dev, skb)) {
 43                 kfree_skb(skb);
 44         } else {
 45                 skb_push(skb, ETH_HLEN);
 46                 br_drop_fake_rtable(skb);
 47                 dev_queue_xmit(skb);
 48         }
 49 
 50         return 0;
 51 }
 52 EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);
 53 
 54 int br_forward_finish(struct sk_buff *skb)
 55 {
 56         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
 57                        br_dev_queue_push_xmit);
 58 
 59 }
 60 EXPORT_SYMBOL_GPL(br_forward_finish);
 61 
 62 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
 63 {
 64         skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb);
 65         if (!skb)
 66                 return;
 67 
 68         skb->dev = to->dev;
 69 
 70         if (unlikely(netpoll_tx_running(to->br->dev))) {
 71                 if (!is_skb_forwardable(skb->dev, skb))
 72                         kfree_skb(skb);
 73                 else {
 74                         skb_push(skb, ETH_HLEN);
 75                         br_netpoll_send_skb(to, skb);
 76                 }
 77                 return;
 78         }
 79 
 80         NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
 81                 br_forward_finish);
 82 }
 83 
 84 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
 85 {
 86         struct net_device *indev;
 87 
 88         if (skb_warn_if_lro(skb)) {
 89                 kfree_skb(skb);
 90                 return;
 91         }
 92 
 93         skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb);
 94         if (!skb)
 95                 return;
 96 
 97         indev = skb->dev;
 98         skb->dev = to->dev;
 99         skb_forward_csum(skb);
100 
101         NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
102                 br_forward_finish);
103 }
104 
105 /* called with rcu_read_lock */
106 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
107 {
108         if (to && should_deliver(to, skb)) {
109                 __br_deliver(to, skb);
110                 return;
111         }
112 
113         kfree_skb(skb);
114 }
115 EXPORT_SYMBOL_GPL(br_deliver);
116 
117 /* called with rcu_read_lock */
118 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0)
119 {
120         if (should_deliver(to, skb)) {
121                 if (skb0)
122                         deliver_clone(to, skb, __br_forward);
123                 else
124                         __br_forward(to, skb);
125                 return;
126         }
127 
128         if (!skb0)
129                 kfree_skb(skb);
130 }
131 
132 static int deliver_clone(const struct net_bridge_port *prev,
133                          struct sk_buff *skb,
134                          void (*__packet_hook)(const struct net_bridge_port *p,
135                                                struct sk_buff *skb))
136 {
137         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
138 
139         skb = skb_clone(skb, GFP_ATOMIC);
140         if (!skb) {
141                 dev->stats.tx_dropped++;
142                 return -ENOMEM;
143         }
144 
145         __packet_hook(prev, skb);
146         return 0;
147 }
148 
149 static struct net_bridge_port *maybe_deliver(
150         struct net_bridge_port *prev, struct net_bridge_port *p,
151         struct sk_buff *skb,
152         void (*__packet_hook)(const struct net_bridge_port *p,
153                               struct sk_buff *skb))
154 {
155         int err;
156 
157         if (!should_deliver(p, skb))
158                 return prev;
159 
160         if (!prev)
161                 goto out;
162 
163         err = deliver_clone(prev, skb, __packet_hook);
164         if (err)
165                 return ERR_PTR(err);
166 
167 out:
168         return p;
169 }
170 
171 /* called under bridge lock */
172 static void br_flood(struct net_bridge *br, struct sk_buff *skb,
173                      struct sk_buff *skb0,
174                      void (*__packet_hook)(const struct net_bridge_port *p,
175                                            struct sk_buff *skb),
176                      bool unicast)
177 {
178         struct net_bridge_port *p;
179         struct net_bridge_port *prev;
180 
181         prev = NULL;
182 
183         list_for_each_entry_rcu(p, &br->port_list, list) {
184                 /* Do not flood unicast traffic to ports that turn it off */
185                 if (unicast && !(p->flags & BR_FLOOD))
186                         continue;
187                 prev = maybe_deliver(prev, p, skb, __packet_hook);
188                 if (IS_ERR(prev))
189                         goto out;
190         }
191 
192         if (!prev)
193                 goto out;
194 
195         if (skb0)
196                 deliver_clone(prev, skb, __packet_hook);
197         else
198                 __packet_hook(prev, skb);
199         return;
200 
201 out:
202         if (!skb0)
203                 kfree_skb(skb);
204 }
205 
206 
207 /* called with rcu_read_lock */
208 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, bool unicast)
209 {
210         br_flood(br, skb, NULL, __br_deliver, unicast);
211 }
212 
213 /* called under bridge lock */
214 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
215                       struct sk_buff *skb2, bool unicast)
216 {
217         br_flood(br, skb, skb2, __br_forward, unicast);
218 }
219 
220 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
221 /* called with rcu_read_lock */
222 static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
223                                struct sk_buff *skb, struct sk_buff *skb0,
224                                void (*__packet_hook)(
225                                         const struct net_bridge_port *p,
226                                         struct sk_buff *skb))
227 {
228         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
229         struct net_bridge *br = netdev_priv(dev);
230         struct net_bridge_port *prev = NULL;
231         struct net_bridge_port_group *p;
232         struct hlist_node *rp;
233 
234         rp = rcu_dereference(hlist_first_rcu(&br->router_list));
235         p = mdst ? rcu_dereference(mdst->ports) : NULL;
236         while (p || rp) {
237                 struct net_bridge_port *port, *lport, *rport;
238 
239                 lport = p ? p->port : NULL;
240                 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
241                              NULL;
242 
243                 port = (unsigned long)lport > (unsigned long)rport ?
244                        lport : rport;
245 
246                 prev = maybe_deliver(prev, port, skb, __packet_hook);
247                 if (IS_ERR(prev))
248                         goto out;
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 (skb0)
260                 deliver_clone(prev, skb, __packet_hook);
261         else
262                 __packet_hook(prev, skb);
263         return;
264 
265 out:
266         if (!skb0)
267                 kfree_skb(skb);
268 }
269 
270 /* called with rcu_read_lock */
271 void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
272                           struct sk_buff *skb)
273 {
274         br_multicast_flood(mdst, skb, NULL, __br_deliver);
275 }
276 
277 /* called with rcu_read_lock */
278 void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
279                           struct sk_buff *skb, struct sk_buff *skb2)
280 {
281         br_multicast_flood(mdst, skb, skb2, __br_forward);
282 }
283 #endif
284 

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