Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf
[sfrench/cifs-2.6.git] / 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