1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Handle incoming frames
4 * Linux ethernet bridge
5 *
6 * Authors:
7 * Lennert Buytenhek <buytenh@gnu.org>
8 */
9
10 #include <linux/slab.h>
11 #include <linux/kernel.h>
12 #include <linux/netdevice.h>
13 #include <linux/etherdevice.h>
14 #include <linux/netfilter_bridge.h>
15 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
16 #include <net/netfilter/nf_queue.h>
17 #endif
18 #include <linux/neighbour.h>
19 #include <net/arp.h>
20 #include <net/dsa.h>
21 #include <linux/export.h>
22 #include <linux/rculist.h>
23 #include "br_private.h"
24 #include "br_private_tunnel.h"
25
26 static int
br_netif_receive_skb(struct net * net,struct sock * sk,struct sk_buff * skb)27 br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
28 {
29 br_drop_fake_rtable(skb);
30 return netif_receive_skb(skb);
31 }
32
br_pass_frame_up(struct sk_buff * skb)33 static int br_pass_frame_up(struct sk_buff *skb)
34 {
35 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
36 struct net_bridge *br = netdev_priv(brdev);
37 struct net_bridge_vlan_group *vg;
38
39 dev_sw_netstats_rx_add(brdev, skb->len);
40
41 vg = br_vlan_group_rcu(br);
42
43 /* Reset the offload_fwd_mark because there could be a stacked
44 * bridge above, and it should not think this bridge it doing
45 * that bridge's work forwarding out its ports.
46 */
47 br_switchdev_frame_unmark(skb);
48
49 /* Bridge is just like any other port. Make sure the
50 * packet is allowed except in promisc mode when someone
51 * may be running packet capture.
52 */
53 if (!(brdev->flags & IFF_PROMISC) &&
54 !br_allowed_egress(vg, skb)) {
55 kfree_skb(skb);
56 return NET_RX_DROP;
57 }
58
59 indev = skb->dev;
60 skb->dev = brdev;
61 skb = br_handle_vlan(br, NULL, vg, skb);
62 if (!skb)
63 return NET_RX_DROP;
64 /* update the multicast stats if the packet is IGMP/MLD */
65 br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb),
66 BR_MCAST_DIR_TX);
67
68 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
69 dev_net(indev), NULL, skb, indev, NULL,
70 br_netif_receive_skb);
71 }
72
73 /* note: already called with rcu_read_lock */
br_handle_frame_finish(struct net * net,struct sock * sk,struct sk_buff * skb)74 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
75 {
76 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
77 enum br_pkt_type pkt_type = BR_PKT_UNICAST;
78 struct net_bridge_fdb_entry *dst = NULL;
79 struct net_bridge_mcast_port *pmctx;
80 struct net_bridge_mdb_entry *mdst;
81 bool local_rcv, mcast_hit = false;
82 struct net_bridge_mcast *brmctx;
83 struct net_bridge_vlan *vlan;
84 struct net_bridge *br;
85 u16 vid = 0;
86 u8 state;
87
88 if (!p)
89 goto drop;
90
91 br = p->br;
92
93 if (br_mst_is_enabled(br)) {
94 state = BR_STATE_FORWARDING;
95 } else {
96 if (p->state == BR_STATE_DISABLED)
97 goto drop;
98
99 state = p->state;
100 }
101
102 brmctx = &p->br->multicast_ctx;
103 pmctx = &p->multicast_ctx;
104 if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid,
105 &state, &vlan))
106 goto out;
107
108 if (p->flags & BR_PORT_LOCKED) {
109 struct net_bridge_fdb_entry *fdb_src =
110 br_fdb_find_rcu(br, eth_hdr(skb)->h_source, vid);
111
112 if (!fdb_src || READ_ONCE(fdb_src->dst) != p ||
113 test_bit(BR_FDB_LOCAL, &fdb_src->flags))
114 goto drop;
115 }
116
117 nbp_switchdev_frame_mark(p, skb);
118
119 /* insert into forwarding database after filtering to avoid spoofing */
120 if (p->flags & BR_LEARNING)
121 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, 0);
122
123 local_rcv = !!(br->dev->flags & IFF_PROMISC);
124 if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) {
125 /* by definition the broadcast is also a multicast address */
126 if (is_broadcast_ether_addr(eth_hdr(skb)->h_dest)) {
127 pkt_type = BR_PKT_BROADCAST;
128 local_rcv = true;
129 } else {
130 pkt_type = BR_PKT_MULTICAST;
131 if (br_multicast_rcv(&brmctx, &pmctx, vlan, skb, vid))
132 goto drop;
133 }
134 }
135
136 if (state == BR_STATE_LEARNING)
137 goto drop;
138
139 BR_INPUT_SKB_CB(skb)->brdev = br->dev;
140 BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED);
141
142 if (IS_ENABLED(CONFIG_INET) &&
143 (skb->protocol == htons(ETH_P_ARP) ||
144 skb->protocol == htons(ETH_P_RARP))) {
145 br_do_proxy_suppress_arp(skb, br, vid, p);
146 } else if (IS_ENABLED(CONFIG_IPV6) &&
147 skb->protocol == htons(ETH_P_IPV6) &&
148 br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) &&
149 pskb_may_pull(skb, sizeof(struct ipv6hdr) +
150 sizeof(struct nd_msg)) &&
151 ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) {
152 struct nd_msg *msg, _msg;
153
154 msg = br_is_nd_neigh_msg(skb, &_msg);
155 if (msg)
156 br_do_suppress_nd(skb, br, vid, p, msg);
157 }
158
159 switch (pkt_type) {
160 case BR_PKT_MULTICAST:
161 mdst = br_mdb_get(brmctx, skb, vid);
162 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
163 br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst)) {
164 if ((mdst && mdst->host_joined) ||
165 br_multicast_is_router(brmctx, skb)) {
166 local_rcv = true;
167 br->dev->stats.multicast++;
168 }
169 mcast_hit = true;
170 } else {
171 local_rcv = true;
172 br->dev->stats.multicast++;
173 }
174 break;
175 case BR_PKT_UNICAST:
176 dst = br_fdb_find_rcu(br, eth_hdr(skb)->h_dest, vid);
177 break;
178 default:
179 break;
180 }
181
182 if (dst) {
183 unsigned long now = jiffies;
184
185 if (test_bit(BR_FDB_LOCAL, &dst->flags))
186 return br_pass_frame_up(skb);
187
188 if (now != dst->used)
189 dst->used = now;
190 br_forward(dst->dst, skb, local_rcv, false);
191 } else {
192 if (!mcast_hit)
193 br_flood(br, skb, pkt_type, local_rcv, false);
194 else
195 br_multicast_flood(mdst, skb, brmctx, local_rcv, false);
196 }
197
198 if (local_rcv)
199 return br_pass_frame_up(skb);
200
201 out:
202 return 0;
203 drop:
204 kfree_skb(skb);
205 goto out;
206 }
207 EXPORT_SYMBOL_GPL(br_handle_frame_finish);
208
__br_handle_local_finish(struct sk_buff * skb)209 static void __br_handle_local_finish(struct sk_buff *skb)
210 {
211 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
212 u16 vid = 0;
213
214 /* check if vlan is allowed, to avoid spoofing */
215 if ((p->flags & BR_LEARNING) &&
216 nbp_state_should_learn(p) &&
217 !br_opt_get(p->br, BROPT_NO_LL_LEARN) &&
218 br_should_learn(p, skb, &vid))
219 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, 0);
220 }
221
222 /* note: already called with rcu_read_lock */
br_handle_local_finish(struct net * net,struct sock * sk,struct sk_buff * skb)223 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
224 {
225 __br_handle_local_finish(skb);
226
227 /* return 1 to signal the okfn() was called so it's ok to use the skb */
228 return 1;
229 }
230
nf_hook_bridge_pre(struct sk_buff * skb,struct sk_buff ** pskb)231 static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb)
232 {
233 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
234 struct nf_hook_entries *e = NULL;
235 struct nf_hook_state state;
236 unsigned int verdict, i;
237 struct net *net;
238 int ret;
239
240 net = dev_net(skb->dev);
241 #ifdef HAVE_JUMP_LABEL
242 if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING]))
243 goto frame_finish;
244 #endif
245
246 e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]);
247 if (!e)
248 goto frame_finish;
249
250 nf_hook_state_init(&state, NF_BR_PRE_ROUTING,
251 NFPROTO_BRIDGE, skb->dev, NULL, NULL,
252 net, br_handle_frame_finish);
253
254 for (i = 0; i < e->num_hook_entries; i++) {
255 verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state);
256 switch (verdict & NF_VERDICT_MASK) {
257 case NF_ACCEPT:
258 if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) {
259 *pskb = skb;
260 return RX_HANDLER_PASS;
261 }
262 break;
263 case NF_DROP:
264 kfree_skb(skb);
265 return RX_HANDLER_CONSUMED;
266 case NF_QUEUE:
267 ret = nf_queue(skb, &state, i, verdict);
268 if (ret == 1)
269 continue;
270 return RX_HANDLER_CONSUMED;
271 default: /* STOLEN */
272 return RX_HANDLER_CONSUMED;
273 }
274 }
275 frame_finish:
276 net = dev_net(skb->dev);
277 br_handle_frame_finish(net, NULL, skb);
278 #else
279 br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
280 #endif
281 return RX_HANDLER_CONSUMED;
282 }
283
284 /* Return 0 if the frame was not processed otherwise 1
285 * note: already called with rcu_read_lock
286 */
br_process_frame_type(struct net_bridge_port * p,struct sk_buff * skb)287 static int br_process_frame_type(struct net_bridge_port *p,
288 struct sk_buff *skb)
289 {
290 struct br_frame_type *tmp;
291
292 hlist_for_each_entry_rcu(tmp, &p->br->frame_type_list, list)
293 if (unlikely(tmp->type == skb->protocol))
294 return tmp->frame_handler(p, skb);
295
296 return 0;
297 }
298
299 /*
300 * Return NULL if skb is handled
301 * note: already called with rcu_read_lock
302 */
br_handle_frame(struct sk_buff ** pskb)303 static rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
304 {
305 struct net_bridge_port *p;
306 struct sk_buff *skb = *pskb;
307 const unsigned char *dest = eth_hdr(skb)->h_dest;
308
309 if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
310 return RX_HANDLER_PASS;
311
312 if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
313 goto drop;
314
315 skb = skb_share_check(skb, GFP_ATOMIC);
316 if (!skb)
317 return RX_HANDLER_CONSUMED;
318
319 memset(skb->cb, 0, sizeof(struct br_input_skb_cb));
320
321 p = br_port_get_rcu(skb->dev);
322 if (p->flags & BR_VLAN_TUNNEL)
323 br_handle_ingress_vlan_tunnel(skb, p, nbp_vlan_group_rcu(p));
324
325 if (unlikely(is_link_local_ether_addr(dest))) {
326 u16 fwd_mask = p->br->group_fwd_mask_required;
327
328 /*
329 * See IEEE 802.1D Table 7-10 Reserved addresses
330 *
331 * Assignment Value
332 * Bridge Group Address 01-80-C2-00-00-00
333 * (MAC Control) 802.3 01-80-C2-00-00-01
334 * (Link Aggregation) 802.3 01-80-C2-00-00-02
335 * 802.1X PAE address 01-80-C2-00-00-03
336 *
337 * 802.1AB LLDP 01-80-C2-00-00-0E
338 *
339 * Others reserved for future standardization
340 */
341 fwd_mask |= p->group_fwd_mask;
342 switch (dest[5]) {
343 case 0x00: /* Bridge Group Address */
344 /* If STP is turned off,
345 then must forward to keep loop detection */
346 if (p->br->stp_enabled == BR_NO_STP ||
347 fwd_mask & (1u << dest[5]))
348 goto forward;
349 *pskb = skb;
350 __br_handle_local_finish(skb);
351 return RX_HANDLER_PASS;
352
353 case 0x01: /* IEEE MAC (Pause) */
354 goto drop;
355
356 case 0x0E: /* 802.1AB LLDP */
357 fwd_mask |= p->br->group_fwd_mask;
358 if (fwd_mask & (1u << dest[5]))
359 goto forward;
360 *pskb = skb;
361 __br_handle_local_finish(skb);
362 return RX_HANDLER_PASS;
363
364 default:
365 /* Allow selective forwarding for most other protocols */
366 fwd_mask |= p->br->group_fwd_mask;
367 if (fwd_mask & (1u << dest[5]))
368 goto forward;
369 }
370
371 /* The else clause should be hit when nf_hook():
372 * - returns < 0 (drop/error)
373 * - returns = 0 (stolen/nf_queue)
374 * Thus return 1 from the okfn() to signal the skb is ok to pass
375 */
376 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
377 dev_net(skb->dev), NULL, skb, skb->dev, NULL,
378 br_handle_local_finish) == 1) {
379 return RX_HANDLER_PASS;
380 } else {
381 return RX_HANDLER_CONSUMED;
382 }
383 }
384
385 if (unlikely(br_process_frame_type(p, skb)))
386 return RX_HANDLER_PASS;
387
388 forward:
389 if (br_mst_is_enabled(p->br))
390 goto defer_stp_filtering;
391
392 switch (p->state) {
393 case BR_STATE_FORWARDING:
394 case BR_STATE_LEARNING:
395 defer_stp_filtering:
396 if (ether_addr_equal(p->br->dev->dev_addr, dest))
397 skb->pkt_type = PACKET_HOST;
398
399 return nf_hook_bridge_pre(skb, pskb);
400 default:
401 drop:
402 kfree_skb(skb);
403 }
404 return RX_HANDLER_CONSUMED;
405 }
406
407 /* This function has no purpose other than to appease the br_port_get_rcu/rtnl
408 * helpers which identify bridged ports according to the rx_handler installed
409 * on them (so there _needs_ to be a bridge rx_handler even if we don't need it
410 * to do anything useful). This bridge won't support traffic to/from the stack,
411 * but only hardware bridging. So return RX_HANDLER_PASS so we don't steal
412 * frames from the ETH_P_XDSA packet_type handler.
413 */
br_handle_frame_dummy(struct sk_buff ** pskb)414 static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb)
415 {
416 return RX_HANDLER_PASS;
417 }
418
br_get_rx_handler(const struct net_device * dev)419 rx_handler_func_t *br_get_rx_handler(const struct net_device *dev)
420 {
421 if (netdev_uses_dsa(dev))
422 return br_handle_frame_dummy;
423
424 return br_handle_frame;
425 }
426
br_add_frame(struct net_bridge * br,struct br_frame_type * ft)427 void br_add_frame(struct net_bridge *br, struct br_frame_type *ft)
428 {
429 hlist_add_head_rcu(&ft->list, &br->frame_type_list);
430 }
431
br_del_frame(struct net_bridge * br,struct br_frame_type * ft)432 void br_del_frame(struct net_bridge *br, struct br_frame_type *ft)
433 {
434 struct br_frame_type *tmp;
435
436 hlist_for_each_entry(tmp, &br->frame_type_list, list)
437 if (ft == tmp) {
438 hlist_del_rcu(&ft->list);
439 return;
440 }
441 }
442