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