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 |
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 | |
33 | static int br_pass_frame_up(struct sk_buff *skb, bool promisc) |
34 | { |
35 | struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev; |
36 | struct net_bridge *br = netdev_priv(dev: brdev); |
37 | struct net_bridge_vlan_group *vg; |
38 | |
39 | dev_sw_netstats_rx_add(dev: brdev, len: 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, type: br_multicast_igmp_type(skb), |
66 | dir: BR_MCAST_DIR_TX); |
67 | |
68 | BR_INPUT_SKB_CB(skb)->promisc = promisc; |
69 | |
70 | return NF_HOOK(pf: NFPROTO_BRIDGE, NF_BR_LOCAL_IN, |
71 | net: dev_net(dev: indev), NULL, skb, in: indev, NULL, |
72 | okfn: br_netif_receive_skb); |
73 | } |
74 | |
75 | /* note: already called with rcu_read_lock */ |
76 | int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb) |
77 | { |
78 | struct net_bridge_port *p = br_port_get_rcu(dev: skb->dev); |
79 | enum br_pkt_type pkt_type = BR_PKT_UNICAST; |
80 | struct net_bridge_fdb_entry *dst = NULL; |
81 | struct net_bridge_mcast_port *pmctx; |
82 | struct net_bridge_mdb_entry *mdst; |
83 | bool local_rcv, mcast_hit = false; |
84 | struct net_bridge_mcast *brmctx; |
85 | struct net_bridge_vlan *vlan; |
86 | struct net_bridge *br; |
87 | bool promisc; |
88 | u16 vid = 0; |
89 | u8 state; |
90 | |
91 | if (!p) |
92 | goto drop; |
93 | |
94 | br = p->br; |
95 | |
96 | if (br_mst_is_enabled(br)) { |
97 | state = BR_STATE_FORWARDING; |
98 | } else { |
99 | if (p->state == BR_STATE_DISABLED) |
100 | goto drop; |
101 | |
102 | state = p->state; |
103 | } |
104 | |
105 | brmctx = &p->br->multicast_ctx; |
106 | pmctx = &p->multicast_ctx; |
107 | if (!br_allowed_ingress(br: p->br, vg: nbp_vlan_group_rcu(p), skb, vid: &vid, |
108 | state: &state, vlan: &vlan)) |
109 | goto out; |
110 | |
111 | if (p->flags & BR_PORT_LOCKED) { |
112 | struct net_bridge_fdb_entry *fdb_src = |
113 | br_fdb_find_rcu(br, addr: eth_hdr(skb)->h_source, vid); |
114 | |
115 | if (!fdb_src) { |
116 | /* FDB miss. Create locked FDB entry if MAB is enabled |
117 | * and drop the packet. |
118 | */ |
119 | if (p->flags & BR_PORT_MAB) |
120 | br_fdb_update(br, source: p, addr: eth_hdr(skb)->h_source, |
121 | vid, BIT(BR_FDB_LOCKED)); |
122 | goto drop; |
123 | } else if (READ_ONCE(fdb_src->dst) != p || |
124 | test_bit(BR_FDB_LOCAL, &fdb_src->flags)) { |
125 | /* FDB mismatch. Drop the packet without roaming. */ |
126 | goto drop; |
127 | } else if (test_bit(BR_FDB_LOCKED, &fdb_src->flags)) { |
128 | /* FDB match, but entry is locked. Refresh it and drop |
129 | * the packet. |
130 | */ |
131 | br_fdb_update(br, source: p, addr: eth_hdr(skb)->h_source, vid, |
132 | BIT(BR_FDB_LOCKED)); |
133 | goto drop; |
134 | } |
135 | } |
136 | |
137 | nbp_switchdev_frame_mark(p, skb); |
138 | |
139 | /* insert into forwarding database after filtering to avoid spoofing */ |
140 | if (p->flags & BR_LEARNING) |
141 | br_fdb_update(br, source: p, addr: eth_hdr(skb)->h_source, vid, flags: 0); |
142 | |
143 | promisc = !!(br->dev->flags & IFF_PROMISC); |
144 | local_rcv = promisc; |
145 | |
146 | if (is_multicast_ether_addr(addr: eth_hdr(skb)->h_dest)) { |
147 | /* by definition the broadcast is also a multicast address */ |
148 | if (is_broadcast_ether_addr(addr: eth_hdr(skb)->h_dest)) { |
149 | pkt_type = BR_PKT_BROADCAST; |
150 | local_rcv = true; |
151 | } else { |
152 | pkt_type = BR_PKT_MULTICAST; |
153 | if (br_multicast_rcv(brmctx: &brmctx, pmctx: &pmctx, vlan, skb, vid)) |
154 | goto drop; |
155 | } |
156 | } |
157 | |
158 | if (state == BR_STATE_LEARNING) |
159 | goto drop; |
160 | |
161 | BR_INPUT_SKB_CB(skb)->brdev = br->dev; |
162 | BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED); |
163 | |
164 | if (IS_ENABLED(CONFIG_INET) && |
165 | (skb->protocol == htons(ETH_P_ARP) || |
166 | skb->protocol == htons(ETH_P_RARP))) { |
167 | br_do_proxy_suppress_arp(skb, br, vid, p); |
168 | } else if (IS_ENABLED(CONFIG_IPV6) && |
169 | skb->protocol == htons(ETH_P_IPV6) && |
170 | br_opt_get(br, opt: BROPT_NEIGH_SUPPRESS_ENABLED) && |
171 | pskb_may_pull(skb, len: sizeof(struct ipv6hdr) + |
172 | sizeof(struct nd_msg)) && |
173 | ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) { |
174 | struct nd_msg *msg, _msg; |
175 | |
176 | msg = br_is_nd_neigh_msg(skb, m: &_msg); |
177 | if (msg) |
178 | br_do_suppress_nd(skb, br, vid, p, msg); |
179 | } |
180 | |
181 | switch (pkt_type) { |
182 | case BR_PKT_MULTICAST: |
183 | mdst = br_mdb_entry_skb_get(brmctx, skb, vid); |
184 | if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && |
185 | br_multicast_querier_exists(brmctx, eth: eth_hdr(skb), mdb: mdst)) { |
186 | if ((mdst && mdst->host_joined) || |
187 | br_multicast_is_router(brmctx, skb)) { |
188 | local_rcv = true; |
189 | DEV_STATS_INC(br->dev, multicast); |
190 | } |
191 | mcast_hit = true; |
192 | } else { |
193 | local_rcv = true; |
194 | DEV_STATS_INC(br->dev, multicast); |
195 | } |
196 | break; |
197 | case BR_PKT_UNICAST: |
198 | dst = br_fdb_find_rcu(br, addr: eth_hdr(skb)->h_dest, vid); |
199 | break; |
200 | default: |
201 | break; |
202 | } |
203 | |
204 | if (dst) { |
205 | unsigned long now = jiffies; |
206 | |
207 | if (test_bit(BR_FDB_LOCAL, &dst->flags)) |
208 | return br_pass_frame_up(skb, promisc: false); |
209 | |
210 | if (now != dst->used) |
211 | dst->used = now; |
212 | br_forward(to: dst->dst, skb, local_rcv, local_orig: false); |
213 | } else { |
214 | if (!mcast_hit) |
215 | br_flood(br, skb, pkt_type, local_rcv, local_orig: false, vid); |
216 | else |
217 | br_multicast_flood(mdst, skb, brmctx, local_rcv, local_orig: false); |
218 | } |
219 | |
220 | if (local_rcv) |
221 | return br_pass_frame_up(skb, promisc); |
222 | |
223 | out: |
224 | return 0; |
225 | drop: |
226 | kfree_skb(skb); |
227 | goto out; |
228 | } |
229 | EXPORT_SYMBOL_GPL(br_handle_frame_finish); |
230 | |
231 | static void __br_handle_local_finish(struct sk_buff *skb) |
232 | { |
233 | struct net_bridge_port *p = br_port_get_rcu(dev: skb->dev); |
234 | u16 vid = 0; |
235 | |
236 | /* check if vlan is allowed, to avoid spoofing */ |
237 | if ((p->flags & BR_LEARNING) && |
238 | nbp_state_should_learn(p) && |
239 | !br_opt_get(br: p->br, opt: BROPT_NO_LL_LEARN) && |
240 | br_should_learn(p, skb, vid: &vid)) |
241 | br_fdb_update(br: p->br, source: p, addr: eth_hdr(skb)->h_source, vid, flags: 0); |
242 | } |
243 | |
244 | /* note: already called with rcu_read_lock */ |
245 | static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb) |
246 | { |
247 | __br_handle_local_finish(skb); |
248 | |
249 | /* return 1 to signal the okfn() was called so it's ok to use the skb */ |
250 | return 1; |
251 | } |
252 | |
253 | static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb) |
254 | { |
255 | #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE |
256 | struct nf_hook_entries *e = NULL; |
257 | struct nf_hook_state state; |
258 | unsigned int verdict, i; |
259 | struct net *net; |
260 | int ret; |
261 | |
262 | net = dev_net(dev: skb->dev); |
263 | #ifdef HAVE_JUMP_LABEL |
264 | if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING])) |
265 | goto frame_finish; |
266 | #endif |
267 | |
268 | e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]); |
269 | if (!e) |
270 | goto frame_finish; |
271 | |
272 | nf_hook_state_init(p: &state, NF_BR_PRE_ROUTING, |
273 | pf: NFPROTO_BRIDGE, indev: skb->dev, NULL, NULL, |
274 | net, okfn: br_handle_frame_finish); |
275 | |
276 | for (i = 0; i < e->num_hook_entries; i++) { |
277 | verdict = nf_hook_entry_hookfn(entry: &e->hooks[i], skb, state: &state); |
278 | switch (verdict & NF_VERDICT_MASK) { |
279 | case NF_ACCEPT: |
280 | if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) { |
281 | *pskb = skb; |
282 | return RX_HANDLER_PASS; |
283 | } |
284 | break; |
285 | case NF_DROP: |
286 | kfree_skb(skb); |
287 | return RX_HANDLER_CONSUMED; |
288 | case NF_QUEUE: |
289 | ret = nf_queue(skb, state: &state, index: i, verdict); |
290 | if (ret == 1) |
291 | continue; |
292 | return RX_HANDLER_CONSUMED; |
293 | default: /* STOLEN */ |
294 | return RX_HANDLER_CONSUMED; |
295 | } |
296 | } |
297 | frame_finish: |
298 | net = dev_net(dev: skb->dev); |
299 | br_handle_frame_finish(net, NULL, skb); |
300 | #else |
301 | br_handle_frame_finish(dev_net(skb->dev), NULL, skb); |
302 | #endif |
303 | return RX_HANDLER_CONSUMED; |
304 | } |
305 | |
306 | /* Return 0 if the frame was not processed otherwise 1 |
307 | * note: already called with rcu_read_lock |
308 | */ |
309 | static int br_process_frame_type(struct net_bridge_port *p, |
310 | struct sk_buff *skb) |
311 | { |
312 | struct br_frame_type *tmp; |
313 | |
314 | hlist_for_each_entry_rcu(tmp, &p->br->frame_type_list, list) |
315 | if (unlikely(tmp->type == skb->protocol)) |
316 | return tmp->frame_handler(p, skb); |
317 | |
318 | return 0; |
319 | } |
320 | |
321 | /* |
322 | * Return NULL if skb is handled |
323 | * note: already called with rcu_read_lock |
324 | */ |
325 | static rx_handler_result_t br_handle_frame(struct sk_buff **pskb) |
326 | { |
327 | struct net_bridge_port *p; |
328 | struct sk_buff *skb = *pskb; |
329 | const unsigned char *dest = eth_hdr(skb)->h_dest; |
330 | |
331 | if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) |
332 | return RX_HANDLER_PASS; |
333 | |
334 | if (!is_valid_ether_addr(addr: eth_hdr(skb)->h_source)) |
335 | goto drop; |
336 | |
337 | skb = skb_share_check(skb, GFP_ATOMIC); |
338 | if (!skb) |
339 | return RX_HANDLER_CONSUMED; |
340 | |
341 | memset(skb->cb, 0, sizeof(struct br_input_skb_cb)); |
342 | br_tc_skb_miss_set(skb, miss: false); |
343 | |
344 | p = br_port_get_rcu(dev: skb->dev); |
345 | if (p->flags & BR_VLAN_TUNNEL) |
346 | br_handle_ingress_vlan_tunnel(skb, p, vg: nbp_vlan_group_rcu(p)); |
347 | |
348 | if (unlikely(is_link_local_ether_addr(dest))) { |
349 | u16 fwd_mask = p->br->group_fwd_mask_required; |
350 | |
351 | /* |
352 | * See IEEE 802.1D Table 7-10 Reserved addresses |
353 | * |
354 | * Assignment Value |
355 | * Bridge Group Address 01-80-C2-00-00-00 |
356 | * (MAC Control) 802.3 01-80-C2-00-00-01 |
357 | * (Link Aggregation) 802.3 01-80-C2-00-00-02 |
358 | * 802.1X PAE address 01-80-C2-00-00-03 |
359 | * |
360 | * 802.1AB LLDP 01-80-C2-00-00-0E |
361 | * |
362 | * Others reserved for future standardization |
363 | */ |
364 | fwd_mask |= p->group_fwd_mask; |
365 | switch (dest[5]) { |
366 | case 0x00: /* Bridge Group Address */ |
367 | /* If STP is turned off, |
368 | then must forward to keep loop detection */ |
369 | if (p->br->stp_enabled == BR_NO_STP || |
370 | fwd_mask & (1u << dest[5])) |
371 | goto forward; |
372 | *pskb = skb; |
373 | __br_handle_local_finish(skb); |
374 | return RX_HANDLER_PASS; |
375 | |
376 | case 0x01: /* IEEE MAC (Pause) */ |
377 | goto drop; |
378 | |
379 | case 0x0E: /* 802.1AB LLDP */ |
380 | fwd_mask |= p->br->group_fwd_mask; |
381 | if (fwd_mask & (1u << dest[5])) |
382 | goto forward; |
383 | *pskb = skb; |
384 | __br_handle_local_finish(skb); |
385 | return RX_HANDLER_PASS; |
386 | |
387 | default: |
388 | /* Allow selective forwarding for most other protocols */ |
389 | fwd_mask |= p->br->group_fwd_mask; |
390 | if (fwd_mask & (1u << dest[5])) |
391 | goto forward; |
392 | } |
393 | |
394 | BR_INPUT_SKB_CB(skb)->promisc = false; |
395 | |
396 | /* The else clause should be hit when nf_hook(): |
397 | * - returns < 0 (drop/error) |
398 | * - returns = 0 (stolen/nf_queue) |
399 | * Thus return 1 from the okfn() to signal the skb is ok to pass |
400 | */ |
401 | if (NF_HOOK(pf: NFPROTO_BRIDGE, NF_BR_LOCAL_IN, |
402 | net: dev_net(dev: skb->dev), NULL, skb, in: skb->dev, NULL, |
403 | okfn: br_handle_local_finish) == 1) { |
404 | return RX_HANDLER_PASS; |
405 | } else { |
406 | return RX_HANDLER_CONSUMED; |
407 | } |
408 | } |
409 | |
410 | if (unlikely(br_process_frame_type(p, skb))) |
411 | return RX_HANDLER_PASS; |
412 | |
413 | forward: |
414 | if (br_mst_is_enabled(br: p->br)) |
415 | goto defer_stp_filtering; |
416 | |
417 | switch (p->state) { |
418 | case BR_STATE_FORWARDING: |
419 | case BR_STATE_LEARNING: |
420 | defer_stp_filtering: |
421 | if (ether_addr_equal(addr1: p->br->dev->dev_addr, addr2: dest)) |
422 | skb->pkt_type = PACKET_HOST; |
423 | |
424 | return nf_hook_bridge_pre(skb, pskb); |
425 | default: |
426 | drop: |
427 | kfree_skb(skb); |
428 | } |
429 | return RX_HANDLER_CONSUMED; |
430 | } |
431 | |
432 | /* This function has no purpose other than to appease the br_port_get_rcu/rtnl |
433 | * helpers which identify bridged ports according to the rx_handler installed |
434 | * on them (so there _needs_ to be a bridge rx_handler even if we don't need it |
435 | * to do anything useful). This bridge won't support traffic to/from the stack, |
436 | * but only hardware bridging. So return RX_HANDLER_PASS so we don't steal |
437 | * frames from the ETH_P_XDSA packet_type handler. |
438 | */ |
439 | static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb) |
440 | { |
441 | return RX_HANDLER_PASS; |
442 | } |
443 | |
444 | rx_handler_func_t *br_get_rx_handler(const struct net_device *dev) |
445 | { |
446 | if (netdev_uses_dsa(dev)) |
447 | return br_handle_frame_dummy; |
448 | |
449 | return br_handle_frame; |
450 | } |
451 | |
452 | void br_add_frame(struct net_bridge *br, struct br_frame_type *ft) |
453 | { |
454 | hlist_add_head_rcu(n: &ft->list, h: &br->frame_type_list); |
455 | } |
456 | |
457 | void br_del_frame(struct net_bridge *br, struct br_frame_type *ft) |
458 | { |
459 | struct br_frame_type *tmp; |
460 | |
461 | hlist_for_each_entry(tmp, &br->frame_type_list, list) |
462 | if (ft == tmp) { |
463 | hlist_del_rcu(n: &ft->list); |
464 | return; |
465 | } |
466 | } |
467 | |