Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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
24static 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 diasabled */
30static 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
38static inline unsigned int packet_length(const struct sk_buff *skb)
39{
40 return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0);
41}
42
43int br_dev_queue_push_xmit(struct sk_buff *skb)
44{
45 /* ip_fragment doesn't copy the MAC header */
46 if (nf_bridge_maybe_copy_header(skb) ||
47 (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))) {
48 kfree_skb(skb);
49 } else {
50 skb_push(skb, ETH_HLEN);
51 br_drop_fake_rtable(skb);
52 dev_queue_xmit(skb);
53 }
54
55 return 0;
56}
57
58int br_forward_finish(struct sk_buff *skb)
59{
60 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
61 br_dev_queue_push_xmit);
62
63}
64
65static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
66{
67 skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb);
68 if (!skb)
69 return;
70
71 skb->dev = to->dev;
72
73 if (unlikely(netpoll_tx_running(to->br->dev))) {
74 if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
75 kfree_skb(skb);
76 else {
77 skb_push(skb, ETH_HLEN);
78 br_netpoll_send_skb(to, skb);
79 }
80 return;
81 }
82
83 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
84 br_forward_finish);
85}
86
87static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
88{
89 struct net_device *indev;
90
91 if (skb_warn_if_lro(skb)) {
92 kfree_skb(skb);
93 return;
94 }
95
96 skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb);
97 if (!skb)
98 return;
99
100 indev = skb->dev;
101 skb->dev = to->dev;
102 skb_forward_csum(skb);
103
104 NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
105 br_forward_finish);
106}
107
108/* called with rcu_read_lock */
109void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
110{
111 if (to && should_deliver(to, skb)) {
112 __br_deliver(to, skb);
113 return;
114 }
115
116 kfree_skb(skb);
117}
118
119/* called with rcu_read_lock */
120void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0)
121{
122 if (should_deliver(to, skb)) {
123 if (skb0)
124 deliver_clone(to, skb, __br_forward);
125 else
126 __br_forward(to, skb);
127 return;
128 }
129
130 if (!skb0)
131 kfree_skb(skb);
132}
133
134static int deliver_clone(const struct net_bridge_port *prev,
135 struct sk_buff *skb,
136 void (*__packet_hook)(const struct net_bridge_port *p,
137 struct sk_buff *skb))
138{
139 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
140
141 skb = skb_clone(skb, GFP_ATOMIC);
142 if (!skb) {
143 dev->stats.tx_dropped++;
144 return -ENOMEM;
145 }
146
147 __packet_hook(prev, skb);
148 return 0;
149}
150
151static struct net_bridge_port *maybe_deliver(
152 struct net_bridge_port *prev, struct net_bridge_port *p,
153 struct sk_buff *skb,
154 void (*__packet_hook)(const struct net_bridge_port *p,
155 struct sk_buff *skb))
156{
157 int err;
158
159 if (!should_deliver(p, skb))
160 return prev;
161
162 if (!prev)
163 goto out;
164
165 err = deliver_clone(prev, skb, __packet_hook);
166 if (err)
167 return ERR_PTR(err);
168
169out:
170 return p;
171}
172
173/* called under bridge lock */
174static void br_flood(struct net_bridge *br, struct sk_buff *skb,
175 struct sk_buff *skb0,
176 void (*__packet_hook)(const struct net_bridge_port *p,
177 struct sk_buff *skb))
178{
179 struct net_bridge_port *p;
180 struct net_bridge_port *prev;
181
182 prev = NULL;
183
184 list_for_each_entry_rcu(p, &br->port_list, list) {
185 prev = maybe_deliver(prev, p, skb, __packet_hook);
186 if (IS_ERR(prev))
187 goto out;
188 }
189
190 if (!prev)
191 goto out;
192
193 if (skb0)
194 deliver_clone(prev, skb, __packet_hook);
195 else
196 __packet_hook(prev, skb);
197 return;
198
199out:
200 if (!skb0)
201 kfree_skb(skb);
202}
203
204
205/* called with rcu_read_lock */
206void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb)
207{
208 br_flood(br, skb, NULL, __br_deliver);
209}
210
211/* called under bridge lock */
212void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
213 struct sk_buff *skb2)
214{
215 br_flood(br, skb, skb2, __br_forward);
216}
217
218#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
219/* called with rcu_read_lock */
220static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
221 struct sk_buff *skb, struct sk_buff *skb0,
222 void (*__packet_hook)(
223 const struct net_bridge_port *p,
224 struct sk_buff *skb))
225{
226 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
227 struct net_bridge *br = netdev_priv(dev);
228 struct net_bridge_port *prev = NULL;
229 struct net_bridge_port_group *p;
230 struct hlist_node *rp;
231
232 rp = rcu_dereference(hlist_first_rcu(&br->router_list));
233 p = mdst ? rcu_dereference(mdst->ports) : NULL;
234 while (p || rp) {
235 struct net_bridge_port *port, *lport, *rport;
236
237 lport = p ? p->port : NULL;
238 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
239 NULL;
240
241 port = (unsigned long)lport > (unsigned long)rport ?
242 lport : rport;
243
244 prev = maybe_deliver(prev, port, skb, __packet_hook);
245 if (IS_ERR(prev))
246 goto out;
247
248 if ((unsigned long)lport >= (unsigned long)port)
249 p = rcu_dereference(p->next);
250 if ((unsigned long)rport >= (unsigned long)port)
251 rp = rcu_dereference(hlist_next_rcu(rp));
252 }
253
254 if (!prev)
255 goto out;
256
257 if (skb0)
258 deliver_clone(prev, skb, __packet_hook);
259 else
260 __packet_hook(prev, skb);
261 return;
262
263out:
264 if (!skb0)
265 kfree_skb(skb);
266}
267
268/* called with rcu_read_lock */
269void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
270 struct sk_buff *skb)
271{
272 br_multicast_flood(mdst, skb, NULL, __br_deliver);
273}
274
275/* called with rcu_read_lock */
276void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
277 struct sk_buff *skb, struct sk_buff *skb2)
278{
279 br_multicast_flood(mdst, skb, skb2, __br_forward);
280}
281#endif