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_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(to: 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(dev: 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(ethertype: skb->protocol)) {
43 int depth;
44
45 if (!vlan_get_protocol_and_depth(skb, type: skb->protocol, depth: &depth))
46 goto drop;
47
48 skb_set_network_header(skb, offset: 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(pf: NFPROTO_BRIDGE, NF_BR_POST_ROUTING,
67 net, sk, skb, NULL, out: skb->dev,
68 okfn: 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(p: to, skb);
85
86 vg = nbp_vlan_group_rcu(p: to);
87 skb = br_handle_vlan(br: to->br, port: 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(dev: indev);
101 } else {
102 if (unlikely(netpoll_tx_running(to->br->dev))) {
103 skb_push(skb, ETH_HLEN);
104 if (!is_skb_forwardable(dev: skb->dev, skb))
105 kfree_skb(skb);
106 else
107 br_netpoll_send_skb(p: to, skb);
108 return;
109 }
110 br_hook = NF_BR_LOCAL_OUT;
111 net = dev_net(dev: skb->dev);
112 indev = NULL;
113 }
114
115 NF_HOOK(pf: NFPROTO_BRIDGE, hook: br_hook,
116 net, NULL, skb, in: indev, out: skb->dev,
117 okfn: 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(to: 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(dev: to->dev) || !netif_running(dev: 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(p: to, skb)) {
163 if (local_rcv)
164 deliver_clone(prev: 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(error: err);
194out:
195 br_multicast_count(br: p->br, p, skb, type: igmp_type, dir: 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, miss: 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 (!(p->flags & BR_FLOOD))
218 continue;
219 break;
220 case BR_PKT_MULTICAST:
221 if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev)
222 continue;
223 break;
224 case BR_PKT_BROADCAST:
225 if (!(p->flags & BR_BCAST_FLOOD) && skb->dev != br->dev)
226 continue;
227 break;
228 }
229
230 /* Do not flood to ports that enable proxy ARP */
231 if (p->flags & BR_PROXYARP)
232 continue;
233 if (BR_INPUT_SKB_CB(skb)->proxyarp_replied &&
234 ((p->flags & BR_PROXYARP_WIFI) ||
235 br_is_neigh_suppress_enabled(p, vid)))
236 continue;
237
238 prev = maybe_deliver(prev, p, skb, local_orig);
239 if (IS_ERR(ptr: prev)) {
240 reason = PTR_ERR(ptr: prev) == -ENOMEM ? SKB_DROP_REASON_NOMEM :
241 SKB_DROP_REASON_NOT_SPECIFIED;
242 goto out;
243 }
244 }
245
246 if (!prev)
247 goto out;
248
249 if (local_rcv)
250 deliver_clone(prev, skb, local_orig);
251 else
252 __br_forward(to: prev, skb, local_orig);
253 return;
254
255out:
256 if (!local_rcv)
257 kfree_skb_reason(skb, reason);
258}
259
260#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
261static void maybe_deliver_addr(struct net_bridge_port *p, struct sk_buff *skb,
262 const unsigned char *addr, bool local_orig)
263{
264 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
265 const unsigned char *src = eth_hdr(skb)->h_source;
266 struct sk_buff *nskb;
267
268 if (!should_deliver(p, skb))
269 return;
270
271 /* Even with hairpin, no soliloquies - prevent breaking IPv6 DAD */
272 if (skb->dev == p->dev && ether_addr_equal(addr1: src, addr2: addr))
273 return;
274
275 __skb_push(skb, ETH_HLEN);
276 nskb = pskb_copy(skb, GFP_ATOMIC);
277 __skb_pull(skb, ETH_HLEN);
278 if (!nskb) {
279 DEV_STATS_INC(dev, tx_dropped);
280 return;
281 }
282
283 skb = nskb;
284 __skb_pull(skb, ETH_HLEN);
285 if (!is_broadcast_ether_addr(addr))
286 memcpy(eth_hdr(skb)->h_dest, addr, ETH_ALEN);
287
288 __br_forward(to: p, skb, local_orig);
289}
290
291/* called with rcu_read_lock */
292void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
293 struct sk_buff *skb,
294 struct net_bridge_mcast *brmctx,
295 bool local_rcv, bool local_orig)
296{
297 enum skb_drop_reason reason = SKB_DROP_REASON_NO_TX_TARGET;
298 struct net_bridge_port *prev = NULL;
299 struct net_bridge_port_group *p;
300 bool allow_mode_include = true;
301 struct hlist_node *rp;
302
303 rp = br_multicast_get_first_rport_node(brmctx, skb);
304
305 if (mdst) {
306 p = rcu_dereference(mdst->ports);
307 if (br_multicast_should_handle_mode(brmctx, proto: mdst->addr.proto) &&
308 br_multicast_is_star_g(ip: &mdst->addr))
309 allow_mode_include = false;
310 } else {
311 p = NULL;
312 br_tc_skb_miss_set(skb, miss: true);
313 }
314
315 while (p || rp) {
316 struct net_bridge_port *port, *lport, *rport;
317
318 lport = p ? p->key.port : NULL;
319 rport = br_multicast_rport_from_node_skb(rp, skb);
320
321 if ((unsigned long)lport > (unsigned long)rport) {
322 port = lport;
323
324 if (port->flags & BR_MULTICAST_TO_UNICAST) {
325 maybe_deliver_addr(p: lport, skb, addr: p->eth_addr,
326 local_orig);
327 goto delivered;
328 }
329 if ((!allow_mode_include &&
330 p->filter_mode == MCAST_INCLUDE) ||
331 (p->flags & MDB_PG_FLAGS_BLOCKED))
332 goto delivered;
333 } else {
334 port = rport;
335 }
336
337 prev = maybe_deliver(prev, p: port, skb, local_orig);
338 if (IS_ERR(ptr: prev)) {
339 reason = PTR_ERR(ptr: prev) == -ENOMEM ? SKB_DROP_REASON_NOMEM :
340 SKB_DROP_REASON_NOT_SPECIFIED;
341 goto out;
342 }
343delivered:
344 if ((unsigned long)lport >= (unsigned long)port)
345 p = rcu_dereference(p->next);
346 if ((unsigned long)rport >= (unsigned long)port)
347 rp = rcu_dereference(hlist_next_rcu(rp));
348 }
349
350 if (!prev)
351 goto out;
352
353 if (local_rcv)
354 deliver_clone(prev, skb, local_orig);
355 else
356 __br_forward(to: prev, skb, local_orig);
357 return;
358
359out:
360 if (!local_rcv)
361 kfree_skb_reason(skb, reason);
362}
363#endif
364

source code of linux/net/bridge/br_forward.c