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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Forwarding decision
4 * Linux ethernet bridge
5 *
6 * Authors:
7 * Lennert Buytenhek <buytenh@gnu.org>
8 */
9
10#include <linux/err.h>
11#include <linux/slab.h>
12#include <linux/kernel.h>
13#include <linux/netdevice.h>
14#include <linux/netpoll.h>
15#include <linux/skbuff.h>
16#include <linux/if_vlan.h>
17#include <linux/netfilter_bridge.h>
18#include "br_private.h"
19
20/* Don't forward packets to originating port or forwarding disabled */
21static inline int should_deliver(const struct net_bridge_port *p,
22 const struct sk_buff *skb)
23{
24 struct net_bridge_vlan_group *vg;
25
26 vg = nbp_vlan_group_rcu(p);
27 return ((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
28 p->state == BR_STATE_FORWARDING && br_allowed_egress(vg, skb) &&
29 nbp_switchdev_allowed_egress(p, skb) &&
30 !br_skb_isolated(p, skb);
31}
32
33int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
34{
35 skb_push(skb, ETH_HLEN);
36 if (!is_skb_forwardable(skb->dev, skb))
37 goto drop;
38
39 br_drop_fake_rtable(skb);
40
41 if (skb->ip_summed == CHECKSUM_PARTIAL &&
42 (skb->protocol == htons(ETH_P_8021Q) ||
43 skb->protocol == htons(ETH_P_8021AD))) {
44 int depth;
45
46 if (!__vlan_get_protocol(skb, skb->protocol, &depth))
47 goto drop;
48
49 skb_set_network_header(skb, depth);
50 }
51
52 dev_queue_xmit(skb);
53
54 return 0;
55
56drop:
57 kfree_skb(skb);
58 return 0;
59}
60EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);
61
62int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
63{
64 skb->tstamp = 0;
65 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING,
66 net, sk, skb, NULL, skb->dev,
67 br_dev_queue_push_xmit);
68
69}
70EXPORT_SYMBOL_GPL(br_forward_finish);
71
72static void __br_forward(const struct net_bridge_port *to,
73 struct sk_buff *skb, bool local_orig)
74{
75 struct net_bridge_vlan_group *vg;
76 struct net_device *indev;
77 struct net *net;
78 int br_hook;
79
80 vg = nbp_vlan_group_rcu(to);
81 skb = br_handle_vlan(to->br, to, vg, skb);
82 if (!skb)
83 return;
84
85 indev = skb->dev;
86 skb->dev = to->dev;
87 if (!local_orig) {
88 if (skb_warn_if_lro(skb)) {
89 kfree_skb(skb);
90 return;
91 }
92 br_hook = NF_BR_FORWARD;
93 skb_forward_csum(skb);
94 net = dev_net(indev);
95 } else {
96 if (unlikely(netpoll_tx_running(to->br->dev))) {
97 skb_push(skb, ETH_HLEN);
98 if (!is_skb_forwardable(skb->dev, skb))
99 kfree_skb(skb);
100 else
101 br_netpoll_send_skb(to, skb);
102 return;
103 }
104 br_hook = NF_BR_LOCAL_OUT;
105 net = dev_net(skb->dev);
106 indev = NULL;
107 }
108
109 NF_HOOK(NFPROTO_BRIDGE, br_hook,
110 net, NULL, skb, indev, skb->dev,
111 br_forward_finish);
112}
113
114static int deliver_clone(const struct net_bridge_port *prev,
115 struct sk_buff *skb, bool local_orig)
116{
117 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
118
119 skb = skb_clone(skb, GFP_ATOMIC);
120 if (!skb) {
121 dev->stats.tx_dropped++;
122 return -ENOMEM;
123 }
124
125 __br_forward(prev, skb, local_orig);
126 return 0;
127}
128
129/**
130 * br_forward - forward a packet to a specific port
131 * @to: destination port
132 * @skb: packet being forwarded
133 * @local_rcv: packet will be received locally after forwarding
134 * @local_orig: packet is locally originated
135 *
136 * Should be called with rcu_read_lock.
137 */
138void br_forward(const struct net_bridge_port *to,
139 struct sk_buff *skb, bool local_rcv, bool local_orig)
140{
141 if (unlikely(!to))
142 goto out;
143
144 /* redirect to backup link if the destination port is down */
145 if (rcu_access_pointer(to->backup_port) && !netif_carrier_ok(to->dev)) {
146 struct net_bridge_port *backup_port;
147
148 backup_port = rcu_dereference(to->backup_port);
149 if (unlikely(!backup_port))
150 goto out;
151 to = backup_port;
152 }
153
154 if (should_deliver(to, skb)) {
155 if (local_rcv)
156 deliver_clone(to, skb, local_orig);
157 else
158 __br_forward(to, skb, local_orig);
159 return;
160 }
161
162out:
163 if (!local_rcv)
164 kfree_skb(skb);
165}
166EXPORT_SYMBOL_GPL(br_forward);
167
168static struct net_bridge_port *maybe_deliver(
169 struct net_bridge_port *prev, struct net_bridge_port *p,
170 struct sk_buff *skb, bool local_orig)
171{
172 u8 igmp_type = br_multicast_igmp_type(skb);
173 int err;
174
175 if (!should_deliver(p, skb))
176 return prev;
177
178 if (!prev)
179 goto out;
180
181 err = deliver_clone(prev, skb, local_orig);
182 if (err)
183 return ERR_PTR(err);
184out:
185 br_multicast_count(p->br, p, skb, igmp_type, BR_MCAST_DIR_TX);
186
187 return p;
188}
189
190/* called under rcu_read_lock */
191void br_flood(struct net_bridge *br, struct sk_buff *skb,
192 enum br_pkt_type pkt_type, bool local_rcv, bool local_orig)
193{
194 struct net_bridge_port *prev = NULL;
195 struct net_bridge_port *p;
196
197 list_for_each_entry_rcu(p, &br->port_list, list) {
198 /* Do not flood unicast traffic to ports that turn it off, nor
199 * other traffic if flood off, except for traffic we originate
200 */
201 switch (pkt_type) {
202 case BR_PKT_UNICAST:
203 if (!(p->flags & BR_FLOOD))
204 continue;
205 break;
206 case BR_PKT_MULTICAST:
207 if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev)
208 continue;
209 break;
210 case BR_PKT_BROADCAST:
211 if (!(p->flags & BR_BCAST_FLOOD) && skb->dev != br->dev)
212 continue;
213 break;
214 }
215
216 /* Do not flood to ports that enable proxy ARP */
217 if (p->flags & BR_PROXYARP)
218 continue;
219 if ((p->flags & (BR_PROXYARP_WIFI | BR_NEIGH_SUPPRESS)) &&
220 BR_INPUT_SKB_CB(skb)->proxyarp_replied)
221 continue;
222
223 prev = maybe_deliver(prev, p, skb, local_orig);
224 if (IS_ERR(prev))
225 goto out;
226 }
227
228 if (!prev)
229 goto out;
230
231 if (local_rcv)
232 deliver_clone(prev, skb, local_orig);
233 else
234 __br_forward(prev, skb, local_orig);
235 return;
236
237out:
238 if (!local_rcv)
239 kfree_skb(skb);
240}
241
242#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
243static void maybe_deliver_addr(struct net_bridge_port *p, struct sk_buff *skb,
244 const unsigned char *addr, bool local_orig)
245{
246 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
247 const unsigned char *src = eth_hdr(skb)->h_source;
248
249 if (!should_deliver(p, skb))
250 return;
251
252 /* Even with hairpin, no soliloquies - prevent breaking IPv6 DAD */
253 if (skb->dev == p->dev && ether_addr_equal(src, addr))
254 return;
255
256 skb = skb_copy(skb, GFP_ATOMIC);
257 if (!skb) {
258 dev->stats.tx_dropped++;
259 return;
260 }
261
262 if (!is_broadcast_ether_addr(addr))
263 memcpy(eth_hdr(skb)->h_dest, addr, ETH_ALEN);
264
265 __br_forward(p, skb, local_orig);
266}
267
268/* called with rcu_read_lock */
269void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
270 struct sk_buff *skb,
271 bool local_rcv, bool local_orig)
272{
273 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
274 struct net_bridge *br = netdev_priv(dev);
275 struct net_bridge_port *prev = NULL;
276 struct net_bridge_port_group *p;
277 struct hlist_node *rp;
278
279 rp = rcu_dereference(hlist_first_rcu(&br->router_list));
280 p = mdst ? rcu_dereference(mdst->ports) : NULL;
281 while (p || rp) {
282 struct net_bridge_port *port, *lport, *rport;
283
284 lport = p ? p->port : NULL;
285 rport = hlist_entry_safe(rp, struct net_bridge_port, rlist);
286
287 if ((unsigned long)lport > (unsigned long)rport) {
288 port = lport;
289
290 if (port->flags & BR_MULTICAST_TO_UNICAST) {
291 maybe_deliver_addr(lport, skb, p->eth_addr,
292 local_orig);
293 goto delivered;
294 }
295 } else {
296 port = rport;
297 }
298
299 prev = maybe_deliver(prev, port, skb, local_orig);
300 if (IS_ERR(prev))
301 goto out;
302delivered:
303 if ((unsigned long)lport >= (unsigned long)port)
304 p = rcu_dereference(p->next);
305 if ((unsigned long)rport >= (unsigned long)port)
306 rp = rcu_dereference(hlist_next_rcu(rp));
307 }
308
309 if (!prev)
310 goto out;
311
312 if (local_rcv)
313 deliver_clone(prev, skb, local_orig);
314 else
315 __br_forward(prev, skb, local_orig);
316 return;
317
318out:
319 if (!local_rcv)
320 kfree_skb(skb);
321}
322#endif
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 */
25static 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
36int 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
59drop:
60 kfree_skb(skb);
61 return 0;
62}
63EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);
64
65int 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}
72EXPORT_SYMBOL_GPL(br_forward_finish);
73
74static 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
117static 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 */
141void 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}
155EXPORT_SYMBOL_GPL(br_forward);
156
157static 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
173out:
174 return p;
175}
176
177/* called under rcu_read_lock */
178void 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
218out:
219 if (!local_rcv)
220 kfree_skb(skb);
221}
222
223#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
224/* called with rcu_read_lock */
225void 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
270out:
271 if (!local_rcv)
272 kfree_skb(skb);
273}
274#endif