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 struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
39
40 u64_stats_update_begin(&brstats->syncp);
41 brstats->rx_packets++;
42 brstats->rx_bytes += skb->len;
43 u64_stats_update_end(&brstats->syncp);
44
45 vg = br_vlan_group_rcu(br);
46 /* Bridge is just like any other port. Make sure the
47 * packet is allowed except in promisc modue when someone
48 * may be running packet capture.
49 */
50 if (!(brdev->flags & IFF_PROMISC) &&
51 !br_allowed_egress(vg, skb)) {
52 kfree_skb(skb);
53 return NET_RX_DROP;
54 }
55
56 indev = skb->dev;
57 skb->dev = brdev;
58 skb = br_handle_vlan(br, NULL, vg, skb);
59 if (!skb)
60 return NET_RX_DROP;
61 /* update the multicast stats if the packet is IGMP/MLD */
62 br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb),
63 BR_MCAST_DIR_TX);
64
65 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
66 dev_net(indev), NULL, skb, indev, NULL,
67 br_netif_receive_skb);
68 }
69
70 /* note: already called with rcu_read_lock */
br_handle_frame_finish(struct net * net,struct sock * sk,struct sk_buff * skb)71 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
72 {
73 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
74 enum br_pkt_type pkt_type = BR_PKT_UNICAST;
75 struct net_bridge_fdb_entry *dst = NULL;
76 struct net_bridge_mdb_entry *mdst;
77 bool local_rcv, mcast_hit = false;
78 struct net_bridge *br;
79 u16 vid = 0;
80 u8 state;
81
82 if (!p || p->state == BR_STATE_DISABLED)
83 goto drop;
84
85 state = p->state;
86 if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid,
87 &state))
88 goto out;
89
90 nbp_switchdev_frame_mark(p, skb);
91
92 /* insert into forwarding database after filtering to avoid spoofing */
93 br = p->br;
94 if (p->flags & BR_LEARNING)
95 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, 0);
96
97 local_rcv = !!(br->dev->flags & IFF_PROMISC);
98 if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) {
99 /* by definition the broadcast is also a multicast address */
100 if (is_broadcast_ether_addr(eth_hdr(skb)->h_dest)) {
101 pkt_type = BR_PKT_BROADCAST;
102 local_rcv = true;
103 } else {
104 pkt_type = BR_PKT_MULTICAST;
105 if (br_multicast_rcv(br, p, skb, vid))
106 goto drop;
107 }
108 }
109
110 if (state == BR_STATE_LEARNING)
111 goto drop;
112
113 BR_INPUT_SKB_CB(skb)->brdev = br->dev;
114 BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED);
115
116 if (IS_ENABLED(CONFIG_INET) &&
117 (skb->protocol == htons(ETH_P_ARP) ||
118 skb->protocol == htons(ETH_P_RARP))) {
119 br_do_proxy_suppress_arp(skb, br, vid, p);
120 } else if (IS_ENABLED(CONFIG_IPV6) &&
121 skb->protocol == htons(ETH_P_IPV6) &&
122 br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) &&
123 pskb_may_pull(skb, sizeof(struct ipv6hdr) +
124 sizeof(struct nd_msg)) &&
125 ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) {
126 struct nd_msg *msg, _msg;
127
128 msg = br_is_nd_neigh_msg(skb, &_msg);
129 if (msg)
130 br_do_suppress_nd(skb, br, vid, p, msg);
131 }
132
133 switch (pkt_type) {
134 case BR_PKT_MULTICAST:
135 mdst = br_mdb_get(br, skb, vid);
136 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
137 br_multicast_querier_exists(br, eth_hdr(skb))) {
138 if ((mdst && mdst->host_joined) ||
139 br_multicast_is_router(br)) {
140 local_rcv = true;
141 br->dev->stats.multicast++;
142 }
143 mcast_hit = true;
144 } else {
145 local_rcv = true;
146 br->dev->stats.multicast++;
147 }
148 break;
149 case BR_PKT_UNICAST:
150 dst = br_fdb_find_rcu(br, eth_hdr(skb)->h_dest, vid);
151 default:
152 break;
153 }
154
155 if (dst) {
156 unsigned long now = jiffies;
157
158 if (test_bit(BR_FDB_LOCAL, &dst->flags))
159 return br_pass_frame_up(skb);
160
161 if (now != dst->used)
162 dst->used = now;
163 br_forward(dst->dst, skb, local_rcv, false);
164 } else {
165 if (!mcast_hit)
166 br_flood(br, skb, pkt_type, local_rcv, false);
167 else
168 br_multicast_flood(mdst, skb, local_rcv, false);
169 }
170
171 if (local_rcv)
172 return br_pass_frame_up(skb);
173
174 out:
175 return 0;
176 drop:
177 kfree_skb(skb);
178 goto out;
179 }
180 EXPORT_SYMBOL_GPL(br_handle_frame_finish);
181
__br_handle_local_finish(struct sk_buff * skb)182 static void __br_handle_local_finish(struct sk_buff *skb)
183 {
184 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
185 u16 vid = 0;
186
187 /* check if vlan is allowed, to avoid spoofing */
188 if ((p->flags & BR_LEARNING) &&
189 nbp_state_should_learn(p) &&
190 !br_opt_get(p->br, BROPT_NO_LL_LEARN) &&
191 br_should_learn(p, skb, &vid))
192 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, 0);
193 }
194
195 /* note: already called with rcu_read_lock */
br_handle_local_finish(struct net * net,struct sock * sk,struct sk_buff * skb)196 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
197 {
198 __br_handle_local_finish(skb);
199
200 /* return 1 to signal the okfn() was called so it's ok to use the skb */
201 return 1;
202 }
203
nf_hook_bridge_pre(struct sk_buff * skb,struct sk_buff ** pskb)204 static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb)
205 {
206 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
207 struct nf_hook_entries *e = NULL;
208 struct nf_hook_state state;
209 unsigned int verdict, i;
210 struct net *net;
211 int ret;
212
213 net = dev_net(skb->dev);
214 #ifdef HAVE_JUMP_LABEL
215 if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING]))
216 goto frame_finish;
217 #endif
218
219 e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]);
220 if (!e)
221 goto frame_finish;
222
223 nf_hook_state_init(&state, NF_BR_PRE_ROUTING,
224 NFPROTO_BRIDGE, skb->dev, NULL, NULL,
225 net, br_handle_frame_finish);
226
227 for (i = 0; i < e->num_hook_entries; i++) {
228 verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state);
229 switch (verdict & NF_VERDICT_MASK) {
230 case NF_ACCEPT:
231 if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) {
232 *pskb = skb;
233 return RX_HANDLER_PASS;
234 }
235 break;
236 case NF_DROP:
237 kfree_skb(skb);
238 return RX_HANDLER_CONSUMED;
239 case NF_QUEUE:
240 ret = nf_queue(skb, &state, i, verdict);
241 if (ret == 1)
242 continue;
243 return RX_HANDLER_CONSUMED;
244 default: /* STOLEN */
245 return RX_HANDLER_CONSUMED;
246 }
247 }
248 frame_finish:
249 net = dev_net(skb->dev);
250 br_handle_frame_finish(net, NULL, skb);
251 #else
252 br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
253 #endif
254 return RX_HANDLER_CONSUMED;
255 }
256
257 /*
258 * Return NULL if skb is handled
259 * note: already called with rcu_read_lock
260 */
br_handle_frame(struct sk_buff ** pskb)261 static rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
262 {
263 struct net_bridge_port *p;
264 struct sk_buff *skb = *pskb;
265 const unsigned char *dest = eth_hdr(skb)->h_dest;
266
267 if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
268 return RX_HANDLER_PASS;
269
270 if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
271 goto drop;
272
273 skb = skb_share_check(skb, GFP_ATOMIC);
274 if (!skb)
275 return RX_HANDLER_CONSUMED;
276
277 memset(skb->cb, 0, sizeof(struct br_input_skb_cb));
278
279 p = br_port_get_rcu(skb->dev);
280 if (p->flags & BR_VLAN_TUNNEL) {
281 if (br_handle_ingress_vlan_tunnel(skb, p,
282 nbp_vlan_group_rcu(p)))
283 goto drop;
284 }
285
286 if (unlikely(is_link_local_ether_addr(dest))) {
287 u16 fwd_mask = p->br->group_fwd_mask_required;
288
289 /*
290 * See IEEE 802.1D Table 7-10 Reserved addresses
291 *
292 * Assignment Value
293 * Bridge Group Address 01-80-C2-00-00-00
294 * (MAC Control) 802.3 01-80-C2-00-00-01
295 * (Link Aggregation) 802.3 01-80-C2-00-00-02
296 * 802.1X PAE address 01-80-C2-00-00-03
297 *
298 * 802.1AB LLDP 01-80-C2-00-00-0E
299 *
300 * Others reserved for future standardization
301 */
302 fwd_mask |= p->group_fwd_mask;
303 switch (dest[5]) {
304 case 0x00: /* Bridge Group Address */
305 /* If STP is turned off,
306 then must forward to keep loop detection */
307 if (p->br->stp_enabled == BR_NO_STP ||
308 fwd_mask & (1u << dest[5]))
309 goto forward;
310 *pskb = skb;
311 __br_handle_local_finish(skb);
312 return RX_HANDLER_PASS;
313
314 case 0x01: /* IEEE MAC (Pause) */
315 goto drop;
316
317 case 0x0E: /* 802.1AB LLDP */
318 fwd_mask |= p->br->group_fwd_mask;
319 if (fwd_mask & (1u << dest[5]))
320 goto forward;
321 *pskb = skb;
322 __br_handle_local_finish(skb);
323 return RX_HANDLER_PASS;
324
325 default:
326 /* Allow selective forwarding for most other protocols */
327 fwd_mask |= p->br->group_fwd_mask;
328 if (fwd_mask & (1u << dest[5]))
329 goto forward;
330 }
331
332 /* The else clause should be hit when nf_hook():
333 * - returns < 0 (drop/error)
334 * - returns = 0 (stolen/nf_queue)
335 * Thus return 1 from the okfn() to signal the skb is ok to pass
336 */
337 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
338 dev_net(skb->dev), NULL, skb, skb->dev, NULL,
339 br_handle_local_finish) == 1) {
340 return RX_HANDLER_PASS;
341 } else {
342 return RX_HANDLER_CONSUMED;
343 }
344 }
345
346 if (unlikely(br_mrp_process(p, skb)))
347 return RX_HANDLER_PASS;
348
349 forward:
350 switch (p->state) {
351 case BR_STATE_FORWARDING:
352 case BR_STATE_LEARNING:
353 if (ether_addr_equal(p->br->dev->dev_addr, dest))
354 skb->pkt_type = PACKET_HOST;
355
356 return nf_hook_bridge_pre(skb, pskb);
357 default:
358 drop:
359 kfree_skb(skb);
360 }
361 return RX_HANDLER_CONSUMED;
362 }
363
364 /* This function has no purpose other than to appease the br_port_get_rcu/rtnl
365 * helpers which identify bridged ports according to the rx_handler installed
366 * on them (so there _needs_ to be a bridge rx_handler even if we don't need it
367 * to do anything useful). This bridge won't support traffic to/from the stack,
368 * but only hardware bridging. So return RX_HANDLER_PASS so we don't steal
369 * frames from the ETH_P_XDSA packet_type handler.
370 */
br_handle_frame_dummy(struct sk_buff ** pskb)371 static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb)
372 {
373 return RX_HANDLER_PASS;
374 }
375
br_get_rx_handler(const struct net_device * dev)376 rx_handler_func_t *br_get_rx_handler(const struct net_device *dev)
377 {
378 if (netdev_uses_dsa(dev))
379 return br_handle_frame_dummy;
380
381 return br_handle_frame;
382 }
383