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 */
should_deliver(const struct net_bridge_port * p,const struct sk_buff * skb)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
br_dev_queue_push_xmit(struct net * net,struct sock * sk,struct sk_buff * skb)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
br_forward_finish(struct net * net,struct sock * sk,struct sk_buff * skb)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
__br_forward(const struct net_bridge_port * to,struct sk_buff * skb,bool local_orig)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
deliver_clone(const struct net_bridge_port * prev,struct sk_buff * skb,bool local_orig)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 */
br_forward(const struct net_bridge_port * to,struct sk_buff * skb,bool local_rcv,bool local_orig)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
maybe_deliver(struct net_bridge_port * prev,struct net_bridge_port * p,struct sk_buff * skb,bool local_orig)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 */
br_flood(struct net_bridge * br,struct sk_buff * skb,enum br_pkt_type pkt_type,bool local_rcv,bool local_orig)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 /* Do not flood if mc off, except for traffic we originate */
190 if (pkt_type == BR_PKT_MULTICAST &&
191 !(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev)
192 continue;
193
194 /* Do not flood to ports that enable proxy ARP */
195 if (p->flags & BR_PROXYARP)
196 continue;
197 if ((p->flags & BR_PROXYARP_WIFI) &&
198 BR_INPUT_SKB_CB(skb)->proxyarp_replied)
199 continue;
200
201 prev = maybe_deliver(prev, p, skb, local_orig);
202 if (IS_ERR(prev))
203 goto out;
204 if (prev == p)
205 br_multicast_count(p->br, p, skb, igmp_type,
206 BR_MCAST_DIR_TX);
207 }
208
209 if (!prev)
210 goto out;
211
212 if (local_rcv)
213 deliver_clone(prev, skb, local_orig);
214 else
215 __br_forward(prev, skb, local_orig);
216 return;
217
218 out:
219 if (!local_rcv)
220 kfree_skb(skb);
221 }
222
223 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
224 /* called with rcu_read_lock */
br_multicast_flood(struct net_bridge_mdb_entry * mdst,struct sk_buff * skb,bool local_rcv,bool local_orig)225 void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
226 struct sk_buff *skb,
227 bool local_rcv, bool local_orig)
228 {
229 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
230 u8 igmp_type = br_multicast_igmp_type(skb);
231 struct net_bridge *br = netdev_priv(dev);
232 struct net_bridge_port *prev = NULL;
233 struct net_bridge_port_group *p;
234 struct hlist_node *rp;
235
236 rp = rcu_dereference(hlist_first_rcu(&br->router_list));
237 p = mdst ? rcu_dereference(mdst->ports) : NULL;
238 while (p || rp) {
239 struct net_bridge_port *port, *lport, *rport;
240
241 lport = p ? p->port : NULL;
242 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
243 NULL;
244
245 port = (unsigned long)lport > (unsigned long)rport ?
246 lport : rport;
247
248 prev = maybe_deliver(prev, port, skb, local_orig);
249 if (IS_ERR(prev))
250 goto out;
251 if (prev == port)
252 br_multicast_count(port->br, port, skb, igmp_type,
253 BR_MCAST_DIR_TX);
254
255 if ((unsigned long)lport >= (unsigned long)port)
256 p = rcu_dereference(p->next);
257 if ((unsigned long)rport >= (unsigned long)port)
258 rp = rcu_dereference(hlist_next_rcu(rp));
259 }
260
261 if (!prev)
262 goto out;
263
264 if (local_rcv)
265 deliver_clone(prev, skb, local_orig);
266 else
267 __br_forward(prev, skb, local_orig);
268 return;
269
270 out:
271 if (!local_rcv)
272 kfree_skb(skb);
273 }
274 #endif
275