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