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) |
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 | return NF_HOOK(pf: NFPROTO_BRIDGE, NF_BR_LOCAL_IN, |
69 | net: dev_net(dev: indev), NULL, skb, in: indev, NULL, |
70 | okfn: br_netif_receive_skb); |
71 | } |
72 | |
73 | /* note: already called with rcu_read_lock */ |
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(dev: 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(br: p->br, vg: nbp_vlan_group_rcu(p), skb, vid: &vid, |
105 | state: &state, vlan: &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, addr: 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, source: p, addr: 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, source: p, addr: 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, source: p, addr: eth_hdr(skb)->h_source, vid, flags: 0); |
139 | |
140 | local_rcv = !!(br->dev->flags & IFF_PROMISC); |
141 | if (is_multicast_ether_addr(addr: eth_hdr(skb)->h_dest)) { |
142 | /* by definition the broadcast is also a multicast address */ |
143 | if (is_broadcast_ether_addr(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: &brmctx, pmctx: &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, opt: BROPT_NEIGH_SUPPRESS_ENABLED) && |
166 | pskb_may_pull(skb, len: 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, m: &_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: eth_hdr(skb), mdb: 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, addr: 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(to: dst->dst, skb, local_rcv, local_orig: false); |
208 | } else { |
209 | if (!mcast_hit) |
210 | br_flood(br, skb, pkt_type, local_rcv, local_orig: false, vid); |
211 | else |
212 | br_multicast_flood(mdst, skb, brmctx, local_rcv, local_orig: false); |
213 | } |
214 | |
215 | if (local_rcv) |
216 | return br_pass_frame_up(skb); |
217 | |
218 | out: |
219 | return 0; |
220 | drop: |
221 | kfree_skb(skb); |
222 | goto out; |
223 | } |
224 | EXPORT_SYMBOL_GPL(br_handle_frame_finish); |
225 | |
226 | static void __br_handle_local_finish(struct sk_buff *skb) |
227 | { |
228 | struct net_bridge_port *p = br_port_get_rcu(dev: 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(br: p->br, opt: BROPT_NO_LL_LEARN) && |
235 | br_should_learn(p, skb, vid: &vid)) |
236 | br_fdb_update(br: p->br, source: p, addr: eth_hdr(skb)->h_source, vid, flags: 0); |
237 | } |
238 | |
239 | /* note: already called with rcu_read_lock */ |
240 | static 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 | |
248 | static 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(dev: 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(p: &state, NF_BR_PRE_ROUTING, |
268 | pf: NFPROTO_BRIDGE, indev: skb->dev, NULL, NULL, |
269 | net, okfn: br_handle_frame_finish); |
270 | |
271 | for (i = 0; i < e->num_hook_entries; i++) { |
272 | verdict = nf_hook_entry_hookfn(entry: &e->hooks[i], skb, state: &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: &state, index: i, verdict); |
285 | if (ret == 1) |
286 | continue; |
287 | return RX_HANDLER_CONSUMED; |
288 | default: /* STOLEN */ |
289 | return RX_HANDLER_CONSUMED; |
290 | } |
291 | } |
292 | frame_finish: |
293 | net = dev_net(dev: 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 | */ |
304 | static 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 | */ |
320 | static 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(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, miss: false); |
338 | |
339 | p = br_port_get_rcu(dev: skb->dev); |
340 | if (p->flags & BR_VLAN_TUNNEL) |
341 | br_handle_ingress_vlan_tunnel(skb, p, vg: 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(pf: NFPROTO_BRIDGE, NF_BR_LOCAL_IN, |
395 | net: dev_net(dev: skb->dev), NULL, skb, in: skb->dev, NULL, |
396 | okfn: 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 | |
406 | forward: |
407 | if (br_mst_is_enabled(br: p->br)) |
408 | goto defer_stp_filtering; |
409 | |
410 | switch (p->state) { |
411 | case BR_STATE_FORWARDING: |
412 | case BR_STATE_LEARNING: |
413 | defer_stp_filtering: |
414 | if (ether_addr_equal(addr1: p->br->dev->dev_addr, addr2: dest)) |
415 | skb->pkt_type = PACKET_HOST; |
416 | |
417 | return nf_hook_bridge_pre(skb, pskb); |
418 | default: |
419 | drop: |
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 | */ |
432 | static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb) |
433 | { |
434 | return RX_HANDLER_PASS; |
435 | } |
436 | |
437 | rx_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 | |
445 | void br_add_frame(struct net_bridge *br, struct br_frame_type *ft) |
446 | { |
447 | hlist_add_head_rcu(n: &ft->list, h: &br->frame_type_list); |
448 | } |
449 | |
450 | void 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(n: &ft->list); |
457 | return; |
458 | } |
459 | } |
460 | |