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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 <[email protected]>
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 (test_bit(BR_HAIRPIN_MODE_BIT, &p->flags) || skb->dev != p->dev) &&
28 (br_mst_is_enabled(p) || 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
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 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
57drop:
58 kfree_skb(skb);
59 return 0;
60}
61EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);
62
63int 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}
71EXPORT_SYMBOL_GPL(br_forward_finish);
72
73static 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
120static 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 */
144void 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) &&
152 (!netif_carrier_ok(to->dev) || !netif_running(to->dev))) {
153 struct net_bridge_port *backup_port;
154
155 backup_port = rcu_dereference(to->backup_port);
156 if (unlikely(!backup_port))
157 goto out;
158 BR_INPUT_SKB_CB(skb)->backup_nhid = READ_ONCE(to->backup_nhid);
159 to = backup_port;
160 }
161
162 if (should_deliver(to, skb)) {
163 if (local_rcv)
164 deliver_clone(to, skb, local_orig);
165 else
166 __br_forward(to, skb, local_orig);
167 return;
168 }
169
170out:
171 if (!local_rcv)
172 kfree_skb(skb);
173}
174EXPORT_SYMBOL_GPL(br_forward);
175
176static struct net_bridge_port *maybe_deliver(
177 struct net_bridge_port *prev, struct net_bridge_port *p,
178 struct sk_buff *skb, bool local_orig)
179{
180 u8 igmp_type = br_multicast_igmp_type(skb);
181 int err;
182
183 if (!should_deliver(p, skb))
184 return prev;
185
186 nbp_switchdev_frame_mark_tx_fwd_to_hwdom(p, skb);
187
188 if (!prev)
189 goto out;
190
191 err = deliver_clone(prev, skb, local_orig);
192 if (err)
193 return ERR_PTR(err);
194out:
195 br_multicast_count(p->br, p, skb, igmp_type, BR_MCAST_DIR_TX);
196
197 return p;
198}
199
200/* called under rcu_read_lock */
201void br_flood(struct net_bridge *br, struct sk_buff *skb,
202 enum br_pkt_type pkt_type, bool local_rcv, bool local_orig,
203 u16 vid)
204{
205 enum skb_drop_reason reason = SKB_DROP_REASON_NO_TX_TARGET;
206 struct net_bridge_port *prev = NULL;
207 struct net_bridge_port *p;
208
209 br_tc_skb_miss_set(skb, pkt_type != BR_PKT_BROADCAST);
210
211 list_for_each_entry_rcu(p, &br->port_list, list) {
212 /* Do not flood unicast traffic to ports that turn it off, nor
213 * other traffic if flood off, except for traffic we originate
214 */
215 switch (pkt_type) {
216 case BR_PKT_UNICAST:
217 if (!test_bit(BR_FLOOD_BIT, &p->flags))
218 continue;
219 break;
220 case BR_PKT_MULTICAST:
221 if (!test_bit(BR_MCAST_FLOOD_BIT, &p->flags) && skb->dev != br->dev)
222 continue;
223 break;
224 case BR_PKT_BROADCAST:
225 if (!test_bit(BR_BCAST_FLOOD_BIT, &p->flags) && skb->dev != br->dev)
226 continue;
227 break;
228 }
229
230 /* Do not flood to ports that enable proxy ARP */
231 if (test_bit(BR_PROXYARP_BIT, &p->flags))
232 continue;
233 if (BR_INPUT_SKB_CB(skb)->proxyarp_replied) {
234 if (test_bit(BR_PROXYARP_WIFI_BIT, &p->flags))
235 continue;
236 /* For gratuitous ARPs/NAs, check neigh_forward_grat.
237 * For regular ARPs/NDs, check only neigh_suppress.
238 */
239 if (br_is_neigh_suppress_enabled(p, vid) &&
240 (!BR_INPUT_SKB_CB(skb)->grat_arp ||
241 !br_is_neigh_forward_grat_enabled(p, vid)))
242 continue;
243 }
244
245 prev = maybe_deliver(prev, p, skb, local_orig);
246 if (IS_ERR(prev)) {
247 reason = PTR_ERR(prev) == -ENOMEM ? SKB_DROP_REASON_NOMEM :
248 SKB_DROP_REASON_NOT_SPECIFIED;
249 goto out;
250 }
251 }
252
253 if (!prev)
254 goto out;
255
256 if (local_rcv)
257 deliver_clone(prev, skb, local_orig);
258 else
259 __br_forward(prev, skb, local_orig);
260 return;
261
262out:
263 if (!local_rcv)
264 kfree_skb_reason(skb, reason);
265}
266
267#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
268static void maybe_deliver_addr(struct net_bridge_port *p, struct sk_buff *skb,
269 const unsigned char *addr, bool local_orig)
270{
271 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
272 const unsigned char *src = eth_hdr(skb)->h_source;
273 struct sk_buff *nskb;
274
275 if (!should_deliver(p, skb))
276 return;
277
278 /* Even with hairpin, no soliloquies - prevent breaking IPv6 DAD */
279 if (skb->dev == p->dev && ether_addr_equal(src, addr))
280 return;
281
282 __skb_push(skb, ETH_HLEN);
283 nskb = pskb_copy(skb, GFP_ATOMIC);
284 __skb_pull(skb, ETH_HLEN);
285 if (!nskb) {
286 DEV_STATS_INC(dev, tx_dropped);
287 return;
288 }
289
290 skb = nskb;
291 __skb_pull(skb, ETH_HLEN);
292 if (!is_broadcast_ether_addr(addr))
293 memcpy(eth_hdr(skb)->h_dest, addr, ETH_ALEN);
294
295 __br_forward(p, skb, local_orig);
296}
297
298/* called with rcu_read_lock */
299void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
300 struct sk_buff *skb,
301 struct net_bridge_mcast *brmctx,
302 bool local_rcv, bool local_orig)
303{
304 enum skb_drop_reason reason = SKB_DROP_REASON_NO_TX_TARGET;
305 struct net_bridge_port *prev = NULL;
306 struct net_bridge_port_group *p;
307 bool allow_mode_include = true;
308 struct hlist_node *rp;
309
310 rp = br_multicast_get_first_rport_node(brmctx, skb);
311
312 if (mdst) {
313 p = rcu_dereference(mdst->ports);
314 if (br_multicast_should_handle_mode(brmctx, mdst->addr.proto) &&
315 br_multicast_is_star_g(&mdst->addr))
316 allow_mode_include = false;
317 } else {
318 p = NULL;
319 br_tc_skb_miss_set(skb, true);
320 }
321
322 while (p || rp) {
323 struct net_bridge_port *port, *lport, *rport;
324
325 lport = p ? p->key.port : NULL;
326 rport = br_multicast_rport_from_node_skb(rp, skb);
327
328 if ((unsigned long)lport > (unsigned long)rport) {
329 port = lport;
330
331 if (test_bit(BR_MULTICAST_TO_UNICAST_BIT,
332 &port->flags)) {
333 maybe_deliver_addr(lport, skb, p->eth_addr,
334 local_orig);
335 goto delivered;
336 }
337 if ((!allow_mode_include &&
338 p->filter_mode == MCAST_INCLUDE) ||
339 (p->flags & MDB_PG_FLAGS_BLOCKED))
340 goto delivered;
341 } else {
342 port = rport;
343 }
344
345 prev = maybe_deliver(prev, port, skb, local_orig);
346 if (IS_ERR(prev)) {
347 reason = PTR_ERR(prev) == -ENOMEM ? SKB_DROP_REASON_NOMEM :
348 SKB_DROP_REASON_NOT_SPECIFIED;
349 goto out;
350 }
351delivered:
352 if ((unsigned long)lport >= (unsigned long)port)
353 p = rcu_dereference(p->next);
354 if ((unsigned long)rport >= (unsigned long)port)
355 rp = rcu_dereference(hlist_next_rcu(rp));
356 }
357
358 if (!prev)
359 goto out;
360
361 if (local_rcv)
362 deliver_clone(prev, skb, local_orig);
363 else
364 __br_forward(prev, skb, local_orig);
365 return;
366
367out:
368 if (!local_rcv)
369 kfree_skb_reason(skb, reason);
370}
371#endif