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 */
21 static 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_mst_is_enabled(p->br) || p->state == BR_STATE_FORWARDING) &&
29 br_allowed_egress(vg, skb) && nbp_switchdev_allowed_egress(p, skb) &&
30 !br_skb_isolated(p, skb);
31 }
32
33 int 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 eth_type_vlan(skb->protocol)) {
43 int depth;
44
45 if (!vlan_get_protocol_and_depth(skb, skb->protocol, &depth))
46 goto drop;
47
48 skb_set_network_header(skb, depth);
49 }
50
51 br_switchdev_frame_set_offload_fwd_mark(skb);
52
53 dev_queue_xmit(skb);
54
55 return 0;
56
57 drop:
58 kfree_skb(skb);
59 return 0;
60 }
61 EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);
62
63 int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
64 {
65 skb_clear_tstamp(skb);
66 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING,
67 net, sk, skb, NULL, skb->dev,
68 br_dev_queue_push_xmit);
69
70 }
71 EXPORT_SYMBOL_GPL(br_forward_finish);
72
73 static void __br_forward(const struct net_bridge_port *to,
74 struct sk_buff *skb, bool local_orig)
75 {
76 struct net_bridge_vlan_group *vg;
77 struct net_device *indev;
78 struct net *net;
79 int br_hook;
80
81 /* Mark the skb for forwarding offload early so that br_handle_vlan()
82 * can know whether to pop the VLAN header on egress or keep it.
83 */
84 nbp_switchdev_frame_mark_tx_fwd_offload(to, skb);
85
86 vg = nbp_vlan_group_rcu(to);
87 skb = br_handle_vlan(to->br, to, vg, skb);
88 if (!skb)
89 return;
90
91 indev = skb->dev;
92 skb->dev = to->dev;
93 if (!local_orig) {
94 if (skb_warn_if_lro(skb)) {
95 kfree_skb(skb);
96 return;
97 }
98 br_hook = NF_BR_FORWARD;
99 skb_forward_csum(skb);
100 net = dev_net(indev);
101 } else {
102 if (unlikely(netpoll_tx_running(to->br->dev))) {
103 skb_push(skb, ETH_HLEN);
104 if (!is_skb_forwardable(skb->dev, skb))
105 kfree_skb(skb);
106 else
107 br_netpoll_send_skb(to, skb);
108 return;
109 }
110 br_hook = NF_BR_LOCAL_OUT;
111 net = dev_net(skb->dev);
112 indev = NULL;
113 }
114
115 NF_HOOK(NFPROTO_BRIDGE, br_hook,
116 net, NULL, skb, indev, skb->dev,
117 br_forward_finish);
118 }
119
120 static int deliver_clone(const struct net_bridge_port *prev,
121 struct sk_buff *skb, bool local_orig)
122 {
123 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
124
125 skb = skb_clone(skb, GFP_ATOMIC);
126 if (!skb) {
127 DEV_STATS_INC(dev, tx_dropped);
128 return -ENOMEM;
129 }
130
131 __br_forward(prev, skb, local_orig);
132 return 0;
133 }
134
135 /**
136 * br_forward - forward a packet to a specific port
137 * @to: destination port
138 * @skb: packet being forwarded
139 * @local_rcv: packet will be received locally after forwarding
140 * @local_orig: packet is locally originated
141 *
142 * Should be called with rcu_read_lock.
143 */
144 void br_forward(const struct net_bridge_port *to,
145 struct sk_buff *skb, bool local_rcv, bool local_orig)
146 {
147 if (unlikely(!to))
148 goto out;
149
150 /* redirect to backup link if the destination port is down */
151 if (rcu_access_pointer(to->backup_port) && !netif_carrier_ok(to->dev)) {
152 struct net_bridge_port *backup_port;
153
154 backup_port = rcu_dereference(to->backup_port);
155 if (unlikely(!backup_port))
156 goto out;
157 BR_INPUT_SKB_CB(skb)->backup_nhid = READ_ONCE(to->backup_nhid);
158 to = backup_port;
159 }
160
161 if (should_deliver(to, skb)) {
162 if (local_rcv)
163 deliver_clone(to, skb, local_orig);
164 else
165 __br_forward(to, skb, local_orig);
166 return;
167 }
168
169 out:
170 if (!local_rcv)
171 kfree_skb(skb);
172 }
173 EXPORT_SYMBOL_GPL(br_forward);
174
175 static struct net_bridge_port *maybe_deliver(
176 struct net_bridge_port *prev, struct net_bridge_port *p,
177 struct sk_buff *skb, bool local_orig)
178 {
179 u8 igmp_type = br_multicast_igmp_type(skb);
180 int err;
181
182 if (!should_deliver(p, skb))
183 return prev;
184
185 nbp_switchdev_frame_mark_tx_fwd_to_hwdom(p, skb);
186
187 if (!prev)
188 goto out;
189
190 err = deliver_clone(prev, skb, local_orig);
191 if (err)
192 return ERR_PTR(err);
193 out:
194 br_multicast_count(p->br, p, skb, igmp_type, BR_MCAST_DIR_TX);
195
196 return p;
197 }
198
199 /* called under rcu_read_lock */
200 void br_flood(struct net_bridge *br, struct sk_buff *skb,
201 enum br_pkt_type pkt_type, bool local_rcv, bool local_orig,
202 u16 vid)
203 {
204 struct net_bridge_port *prev = NULL;
205 struct net_bridge_port *p;
206
207 br_tc_skb_miss_set(skb, pkt_type != BR_PKT_BROADCAST);
208
209 list_for_each_entry_rcu(p, &br->port_list, list) {
210 /* Do not flood unicast traffic to ports that turn it off, nor
211 * other traffic if flood off, except for traffic we originate
212 */
213 switch (pkt_type) {
214 case BR_PKT_UNICAST:
215 if (!(p->flags & BR_FLOOD))
216 continue;
217 break;
218 case BR_PKT_MULTICAST:
219 if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev)
220 continue;
221 break;
222 case BR_PKT_BROADCAST:
223 if (!(p->flags & BR_BCAST_FLOOD) && skb->dev != br->dev)
224 continue;
225 break;
226 }
227
228 /* Do not flood to ports that enable proxy ARP */
229 if (p->flags & BR_PROXYARP)
230 continue;
231 if (BR_INPUT_SKB_CB(skb)->proxyarp_replied &&
232 ((p->flags & BR_PROXYARP_WIFI) ||
233 br_is_neigh_suppress_enabled(p, vid)))
234 continue;
235
236 prev = maybe_deliver(prev, p, skb, local_orig);
237 if (IS_ERR(prev))
238 goto out;
239 }
240
241 if (!prev)
242 goto out;
243
244 if (local_rcv)
245 deliver_clone(prev, skb, local_orig);
246 else
247 __br_forward(prev, skb, local_orig);
248 return;
249
250 out:
251 if (!local_rcv)
252 kfree_skb(skb);
253 }
254
255 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
256 static void maybe_deliver_addr(struct net_bridge_port *p, struct sk_buff *skb,
257 const unsigned char *addr, bool local_orig)
258 {
259 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
260 const unsigned char *src = eth_hdr(skb)->h_source;
261 struct sk_buff *nskb;
262
263 if (!should_deliver(p, skb))
264 return;
265
266 /* Even with hairpin, no soliloquies - prevent breaking IPv6 DAD */
267 if (skb->dev == p->dev && ether_addr_equal(src, addr))
268 return;
269
270 __skb_push(skb, ETH_HLEN);
271 nskb = pskb_copy(skb, GFP_ATOMIC);
272 __skb_pull(skb, ETH_HLEN);
273 if (!nskb) {
274 DEV_STATS_INC(dev, tx_dropped);
275 return;
276 }
277
278 skb = nskb;
279 __skb_pull(skb, ETH_HLEN);
280 if (!is_broadcast_ether_addr(addr))
281 memcpy(eth_hdr(skb)->h_dest, addr, ETH_ALEN);
282
283 __br_forward(p, skb, local_orig);
284 }
285
286 /* called with rcu_read_lock */
287 void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
288 struct sk_buff *skb,
289 struct net_bridge_mcast *brmctx,
290 bool local_rcv, bool local_orig)
291 {
292 struct net_bridge_port *prev = NULL;
293 struct net_bridge_port_group *p;
294 bool allow_mode_include = true;
295 struct hlist_node *rp;
296
297 rp = br_multicast_get_first_rport_node(brmctx, skb);
298
299 if (mdst) {
300 p = rcu_dereference(mdst->ports);
301 if (br_multicast_should_handle_mode(brmctx, mdst->addr.proto) &&
302 br_multicast_is_star_g(&mdst->addr))
303 allow_mode_include = false;
304 } else {
305 p = NULL;
306 br_tc_skb_miss_set(skb, true);
307 }
308
309 while (p || rp) {
310 struct net_bridge_port *port, *lport, *rport;
311
312 lport = p ? p->key.port : NULL;
313 rport = br_multicast_rport_from_node_skb(rp, skb);
314
315 if ((unsigned long)lport > (unsigned long)rport) {
316 port = lport;
317
318 if (port->flags & BR_MULTICAST_TO_UNICAST) {
319 maybe_deliver_addr(lport, skb, p->eth_addr,
320 local_orig);
321 goto delivered;
322 }
323 if ((!allow_mode_include &&
324 p->filter_mode == MCAST_INCLUDE) ||
325 (p->flags & MDB_PG_FLAGS_BLOCKED))
326 goto delivered;
327 } else {
328 port = rport;
329 }
330
331 prev = maybe_deliver(prev, port, skb, local_orig);
332 if (IS_ERR(prev))
333 goto out;
334 delivered:
335 if ((unsigned long)lport >= (unsigned long)port)
336 p = rcu_dereference(p->next);
337 if ((unsigned long)rport >= (unsigned long)port)
338 rp = rcu_dereference(hlist_next_rcu(rp));
339 }
340
341 if (!prev)
342 goto out;
343
344 if (local_rcv)
345 deliver_clone(prev, skb, local_orig);
346 else
347 __br_forward(prev, skb, local_orig);
348 return;
349
350 out:
351 if (!local_rcv)
352 kfree_skb(skb);
353 }
354 #endif
355
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