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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
26static int
27br_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
33static 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 */
74int 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) {
113 /* FDB miss. Create locked FDB entry if MAB is enabled
114 * and drop the packet.
115 */
116 if (p->flags & BR_PORT_MAB)
117 br_fdb_update(br, p, eth_hdr(skb)->h_source,
118 vid, BIT(BR_FDB_LOCKED));
119 goto drop;
120 } else if (READ_ONCE(fdb_src->dst) != p ||
121 test_bit(BR_FDB_LOCAL, &fdb_src->flags)) {
122 /* FDB mismatch. Drop the packet without roaming. */
123 goto drop;
124 } else if (test_bit(BR_FDB_LOCKED, &fdb_src->flags)) {
125 /* FDB match, but entry is locked. Refresh it and drop
126 * the packet.
127 */
128 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid,
129 BIT(BR_FDB_LOCKED));
130 goto drop;
131 }
132 }
133
134 nbp_switchdev_frame_mark(p, skb);
135
136 /* insert into forwarding database after filtering to avoid spoofing */
137 if (p->flags & BR_LEARNING)
138 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, 0);
139
140 local_rcv = !!(br->dev->flags & IFF_PROMISC);
141 if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) {
142 /* by definition the broadcast is also a multicast address */
143 if (is_broadcast_ether_addr(eth_hdr(skb)->h_dest)) {
144 pkt_type = BR_PKT_BROADCAST;
145 local_rcv = true;
146 } else {
147 pkt_type = BR_PKT_MULTICAST;
148 if (br_multicast_rcv(&brmctx, &pmctx, vlan, skb, vid))
149 goto drop;
150 }
151 }
152
153 if (state == BR_STATE_LEARNING)
154 goto drop;
155
156 BR_INPUT_SKB_CB(skb)->brdev = br->dev;
157 BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED);
158
159 if (IS_ENABLED(CONFIG_INET) &&
160 (skb->protocol == htons(ETH_P_ARP) ||
161 skb->protocol == htons(ETH_P_RARP))) {
162 br_do_proxy_suppress_arp(skb, br, vid, p);
163 } else if (IS_ENABLED(CONFIG_IPV6) &&
164 skb->protocol == htons(ETH_P_IPV6) &&
165 br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) &&
166 pskb_may_pull(skb, sizeof(struct ipv6hdr) +
167 sizeof(struct nd_msg)) &&
168 ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) {
169 struct nd_msg *msg, _msg;
170
171 msg = br_is_nd_neigh_msg(skb, &_msg);
172 if (msg)
173 br_do_suppress_nd(skb, br, vid, p, msg);
174 }
175
176 switch (pkt_type) {
177 case BR_PKT_MULTICAST:
178 mdst = br_mdb_entry_skb_get(brmctx, skb, vid);
179 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
180 br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst)) {
181 if ((mdst && mdst->host_joined) ||
182 br_multicast_is_router(brmctx, skb)) {
183 local_rcv = true;
184 DEV_STATS_INC(br->dev, multicast);
185 }
186 mcast_hit = true;
187 } else {
188 local_rcv = true;
189 DEV_STATS_INC(br->dev, multicast);
190 }
191 break;
192 case BR_PKT_UNICAST:
193 dst = br_fdb_find_rcu(br, eth_hdr(skb)->h_dest, vid);
194 break;
195 default:
196 break;
197 }
198
199 if (dst) {
200 unsigned long now = jiffies;
201
202 if (test_bit(BR_FDB_LOCAL, &dst->flags))
203 return br_pass_frame_up(skb);
204
205 if (now != dst->used)
206 dst->used = now;
207 br_forward(dst->dst, skb, local_rcv, false);
208 } else {
209 if (!mcast_hit)
210 br_flood(br, skb, pkt_type, local_rcv, false, vid);
211 else
212 br_multicast_flood(mdst, skb, brmctx, local_rcv, false);
213 }
214
215 if (local_rcv)
216 return br_pass_frame_up(skb);
217
218out:
219 return 0;
220drop:
221 kfree_skb(skb);
222 goto out;
223}
224EXPORT_SYMBOL_GPL(br_handle_frame_finish);
225
226static void __br_handle_local_finish(struct sk_buff *skb)
227{
228 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
229 u16 vid = 0;
230
231 /* check if vlan is allowed, to avoid spoofing */
232 if ((p->flags & BR_LEARNING) &&
233 nbp_state_should_learn(p) &&
234 !br_opt_get(p->br, BROPT_NO_LL_LEARN) &&
235 br_should_learn(p, skb, &vid))
236 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, 0);
237}
238
239/* note: already called with rcu_read_lock */
240static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
241{
242 __br_handle_local_finish(skb);
243
244 /* return 1 to signal the okfn() was called so it's ok to use the skb */
245 return 1;
246}
247
248static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb)
249{
250#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
251 struct nf_hook_entries *e = NULL;
252 struct nf_hook_state state;
253 unsigned int verdict, i;
254 struct net *net;
255 int ret;
256
257 net = dev_net(skb->dev);
258#ifdef HAVE_JUMP_LABEL
259 if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING]))
260 goto frame_finish;
261#endif
262
263 e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]);
264 if (!e)
265 goto frame_finish;
266
267 nf_hook_state_init(&state, NF_BR_PRE_ROUTING,
268 NFPROTO_BRIDGE, skb->dev, NULL, NULL,
269 net, br_handle_frame_finish);
270
271 for (i = 0; i < e->num_hook_entries; i++) {
272 verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state);
273 switch (verdict & NF_VERDICT_MASK) {
274 case NF_ACCEPT:
275 if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) {
276 *pskb = skb;
277 return RX_HANDLER_PASS;
278 }
279 break;
280 case NF_DROP:
281 kfree_skb(skb);
282 return RX_HANDLER_CONSUMED;
283 case NF_QUEUE:
284 ret = nf_queue(skb, &state, i, verdict);
285 if (ret == 1)
286 continue;
287 return RX_HANDLER_CONSUMED;
288 default: /* STOLEN */
289 return RX_HANDLER_CONSUMED;
290 }
291 }
292frame_finish:
293 net = dev_net(skb->dev);
294 br_handle_frame_finish(net, NULL, skb);
295#else
296 br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
297#endif
298 return RX_HANDLER_CONSUMED;
299}
300
301/* Return 0 if the frame was not processed otherwise 1
302 * note: already called with rcu_read_lock
303 */
304static int br_process_frame_type(struct net_bridge_port *p,
305 struct sk_buff *skb)
306{
307 struct br_frame_type *tmp;
308
309 hlist_for_each_entry_rcu(tmp, &p->br->frame_type_list, list)
310 if (unlikely(tmp->type == skb->protocol))
311 return tmp->frame_handler(p, skb);
312
313 return 0;
314}
315
316/*
317 * Return NULL if skb is handled
318 * note: already called with rcu_read_lock
319 */
320static rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
321{
322 struct net_bridge_port *p;
323 struct sk_buff *skb = *pskb;
324 const unsigned char *dest = eth_hdr(skb)->h_dest;
325
326 if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
327 return RX_HANDLER_PASS;
328
329 if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
330 goto drop;
331
332 skb = skb_share_check(skb, GFP_ATOMIC);
333 if (!skb)
334 return RX_HANDLER_CONSUMED;
335
336 memset(skb->cb, 0, sizeof(struct br_input_skb_cb));
337 br_tc_skb_miss_set(skb, false);
338
339 p = br_port_get_rcu(skb->dev);
340 if (p->flags & BR_VLAN_TUNNEL)
341 br_handle_ingress_vlan_tunnel(skb, p, nbp_vlan_group_rcu(p));
342
343 if (unlikely(is_link_local_ether_addr(dest))) {
344 u16 fwd_mask = p->br->group_fwd_mask_required;
345
346 /*
347 * See IEEE 802.1D Table 7-10 Reserved addresses
348 *
349 * Assignment Value
350 * Bridge Group Address 01-80-C2-00-00-00
351 * (MAC Control) 802.3 01-80-C2-00-00-01
352 * (Link Aggregation) 802.3 01-80-C2-00-00-02
353 * 802.1X PAE address 01-80-C2-00-00-03
354 *
355 * 802.1AB LLDP 01-80-C2-00-00-0E
356 *
357 * Others reserved for future standardization
358 */
359 fwd_mask |= p->group_fwd_mask;
360 switch (dest[5]) {
361 case 0x00: /* Bridge Group Address */
362 /* If STP is turned off,
363 then must forward to keep loop detection */
364 if (p->br->stp_enabled == BR_NO_STP ||
365 fwd_mask & (1u << dest[5]))
366 goto forward;
367 *pskb = skb;
368 __br_handle_local_finish(skb);
369 return RX_HANDLER_PASS;
370
371 case 0x01: /* IEEE MAC (Pause) */
372 goto drop;
373
374 case 0x0E: /* 802.1AB LLDP */
375 fwd_mask |= p->br->group_fwd_mask;
376 if (fwd_mask & (1u << dest[5]))
377 goto forward;
378 *pskb = skb;
379 __br_handle_local_finish(skb);
380 return RX_HANDLER_PASS;
381
382 default:
383 /* Allow selective forwarding for most other protocols */
384 fwd_mask |= p->br->group_fwd_mask;
385 if (fwd_mask & (1u << dest[5]))
386 goto forward;
387 }
388
389 /* The else clause should be hit when nf_hook():
390 * - returns < 0 (drop/error)
391 * - returns = 0 (stolen/nf_queue)
392 * Thus return 1 from the okfn() to signal the skb is ok to pass
393 */
394 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
395 dev_net(skb->dev), NULL, skb, skb->dev, NULL,
396 br_handle_local_finish) == 1) {
397 return RX_HANDLER_PASS;
398 } else {
399 return RX_HANDLER_CONSUMED;
400 }
401 }
402
403 if (unlikely(br_process_frame_type(p, skb)))
404 return RX_HANDLER_PASS;
405
406forward:
407 if (br_mst_is_enabled(p->br))
408 goto defer_stp_filtering;
409
410 switch (p->state) {
411 case BR_STATE_FORWARDING:
412 case BR_STATE_LEARNING:
413defer_stp_filtering:
414 if (ether_addr_equal(p->br->dev->dev_addr, dest))
415 skb->pkt_type = PACKET_HOST;
416
417 return nf_hook_bridge_pre(skb, pskb);
418 default:
419drop:
420 kfree_skb(skb);
421 }
422 return RX_HANDLER_CONSUMED;
423}
424
425/* This function has no purpose other than to appease the br_port_get_rcu/rtnl
426 * helpers which identify bridged ports according to the rx_handler installed
427 * on them (so there _needs_ to be a bridge rx_handler even if we don't need it
428 * to do anything useful). This bridge won't support traffic to/from the stack,
429 * but only hardware bridging. So return RX_HANDLER_PASS so we don't steal
430 * frames from the ETH_P_XDSA packet_type handler.
431 */
432static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb)
433{
434 return RX_HANDLER_PASS;
435}
436
437rx_handler_func_t *br_get_rx_handler(const struct net_device *dev)
438{
439 if (netdev_uses_dsa(dev))
440 return br_handle_frame_dummy;
441
442 return br_handle_frame;
443}
444
445void br_add_frame(struct net_bridge *br, struct br_frame_type *ft)
446{
447 hlist_add_head_rcu(&ft->list, &br->frame_type_list);
448}
449
450void br_del_frame(struct net_bridge *br, struct br_frame_type *ft)
451{
452 struct br_frame_type *tmp;
453
454 hlist_for_each_entry(tmp, &br->frame_type_list, list)
455 if (ft == tmp) {
456 hlist_del_rcu(&ft->list);
457 return;
458 }
459}
1/*
2 * Handle incoming frames
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/slab.h>
15#include <linux/kernel.h>
16#include <linux/netdevice.h>
17#include <linux/etherdevice.h>
18#include <linux/netfilter_bridge.h>
19#include "br_private.h"
20
21/* Bridge group multicast address 802.1d (pg 51). */
22const u8 br_group_address[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 };
23
24/* Hook for brouter */
25br_should_route_hook_t __rcu *br_should_route_hook __read_mostly;
26EXPORT_SYMBOL(br_should_route_hook);
27
28static int br_pass_frame_up(struct sk_buff *skb)
29{
30 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
31 struct net_bridge *br = netdev_priv(brdev);
32 struct br_cpu_netstats *brstats = this_cpu_ptr(br->stats);
33
34 u64_stats_update_begin(&brstats->syncp);
35 brstats->rx_packets++;
36 brstats->rx_bytes += skb->len;
37 u64_stats_update_end(&brstats->syncp);
38
39 indev = skb->dev;
40 skb->dev = brdev;
41
42 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL,
43 netif_receive_skb);
44}
45
46/* note: already called with rcu_read_lock */
47int br_handle_frame_finish(struct sk_buff *skb)
48{
49 const unsigned char *dest = eth_hdr(skb)->h_dest;
50 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
51 struct net_bridge *br;
52 struct net_bridge_fdb_entry *dst;
53 struct net_bridge_mdb_entry *mdst;
54 struct sk_buff *skb2;
55
56 if (!p || p->state == BR_STATE_DISABLED)
57 goto drop;
58
59 /* insert into forwarding database after filtering to avoid spoofing */
60 br = p->br;
61 br_fdb_update(br, p, eth_hdr(skb)->h_source);
62
63 if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) &&
64 br_multicast_rcv(br, p, skb))
65 goto drop;
66
67 if (p->state == BR_STATE_LEARNING)
68 goto drop;
69
70 BR_INPUT_SKB_CB(skb)->brdev = br->dev;
71
72 /* The packet skb2 goes to the local host (NULL to skip). */
73 skb2 = NULL;
74
75 if (br->dev->flags & IFF_PROMISC)
76 skb2 = skb;
77
78 dst = NULL;
79
80 if (is_broadcast_ether_addr(dest))
81 skb2 = skb;
82 else if (is_multicast_ether_addr(dest)) {
83 mdst = br_mdb_get(br, skb);
84 if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) {
85 if ((mdst && mdst->mglist) ||
86 br_multicast_is_router(br))
87 skb2 = skb;
88 br_multicast_forward(mdst, skb, skb2);
89 skb = NULL;
90 if (!skb2)
91 goto out;
92 } else
93 skb2 = skb;
94
95 br->dev->stats.multicast++;
96 } else if ((dst = __br_fdb_get(br, dest)) && dst->is_local) {
97 skb2 = skb;
98 /* Do not forward the packet since it's local. */
99 skb = NULL;
100 }
101
102 if (skb) {
103 if (dst) {
104 dst->used = jiffies;
105 br_forward(dst->dst, skb, skb2);
106 } else
107 br_flood_forward(br, skb, skb2);
108 }
109
110 if (skb2)
111 return br_pass_frame_up(skb2);
112
113out:
114 return 0;
115drop:
116 kfree_skb(skb);
117 goto out;
118}
119
120/* note: already called with rcu_read_lock */
121static int br_handle_local_finish(struct sk_buff *skb)
122{
123 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
124
125 br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
126 return 0; /* process further */
127}
128
129/* Does address match the link local multicast address.
130 * 01:80:c2:00:00:0X
131 */
132static inline int is_link_local(const unsigned char *dest)
133{
134 __be16 *a = (__be16 *)dest;
135 static const __be16 *b = (const __be16 *)br_group_address;
136 static const __be16 m = cpu_to_be16(0xfff0);
137
138 return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0;
139}
140
141/*
142 * Return NULL if skb is handled
143 * note: already called with rcu_read_lock
144 */
145rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
146{
147 struct net_bridge_port *p;
148 struct sk_buff *skb = *pskb;
149 const unsigned char *dest = eth_hdr(skb)->h_dest;
150 br_should_route_hook_t *rhook;
151
152 if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
153 return RX_HANDLER_PASS;
154
155 if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
156 goto drop;
157
158 skb = skb_share_check(skb, GFP_ATOMIC);
159 if (!skb)
160 return RX_HANDLER_CONSUMED;
161
162 p = br_port_get_rcu(skb->dev);
163
164 if (unlikely(is_link_local(dest))) {
165 /* Pause frames shouldn't be passed up by driver anyway */
166 if (skb->protocol == htons(ETH_P_PAUSE))
167 goto drop;
168
169 /* If STP is turned off, then forward */
170 if (p->br->stp_enabled == BR_NO_STP && dest[5] == 0)
171 goto forward;
172
173 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
174 NULL, br_handle_local_finish)) {
175 return RX_HANDLER_CONSUMED; /* consumed by filter */
176 } else {
177 *pskb = skb;
178 return RX_HANDLER_PASS; /* continue processing */
179 }
180 }
181
182forward:
183 switch (p->state) {
184 case BR_STATE_FORWARDING:
185 rhook = rcu_dereference(br_should_route_hook);
186 if (rhook) {
187 if ((*rhook)(skb)) {
188 *pskb = skb;
189 return RX_HANDLER_PASS;
190 }
191 dest = eth_hdr(skb)->h_dest;
192 }
193 /* fall through */
194 case BR_STATE_LEARNING:
195 if (!compare_ether_addr(p->br->dev->dev_addr, dest))
196 skb->pkt_type = PACKET_HOST;
197
198 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
199 br_handle_frame_finish);
200 break;
201 default:
202drop:
203 kfree_skb(skb);
204 }
205 return RX_HANDLER_CONSUMED;
206}