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, bool promisc)
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	BR_INPUT_SKB_CB(skb)->promisc = promisc;
69
70	return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
71		       dev_net(indev), NULL, skb, indev, NULL,
72		       br_netif_receive_skb);
73}
74
75/* note: already called with rcu_read_lock */
76int 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(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(p->br, nbp_vlan_group_rcu(p), skb, &vid,
108				&state, &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, 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, p, 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, p, 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, p, eth_hdr(skb)->h_source, vid, 0);
142
143	promisc = !!(br->dev->flags & IFF_PROMISC);
144	local_rcv = promisc;
145
146	if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) {
147		/* by definition the broadcast is also a multicast address */
148		if (is_broadcast_ether_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, &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, BROPT_NEIGH_SUPPRESS_ENABLED) &&
171		   pskb_may_pull(skb, 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, &_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_hdr(skb), 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, 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, false);
209
210		if (now != dst->used)
211			dst->used = now;
212		br_forward(dst->dst, skb, local_rcv, false);
213	} else {
214		if (!mcast_hit)
215			br_flood(br, skb, pkt_type, local_rcv, false, vid);
216		else
217			br_multicast_flood(mdst, skb, brmctx, local_rcv, false);
218	}
219
220	if (local_rcv)
221		return br_pass_frame_up(skb, promisc);
222
223out:
224	return 0;
225drop:
226	kfree_skb(skb);
227	goto out;
228}
229EXPORT_SYMBOL_GPL(br_handle_frame_finish);
230
231static void __br_handle_local_finish(struct sk_buff *skb)
232{
233	struct net_bridge_port *p = br_port_get_rcu(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(p->br, BROPT_NO_LL_LEARN) &&
240	    br_should_learn(p, skb, &vid))
241		br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, 0);
242}
243
244/* note: already called with rcu_read_lock */
245static 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
253static 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(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(&state, NF_BR_PRE_ROUTING,
273			   NFPROTO_BRIDGE, skb->dev, NULL, NULL,
274			   net, br_handle_frame_finish);
275
276	for (i = 0; i < e->num_hook_entries; i++) {
277		verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &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, i, verdict);
290			if (ret == 1)
291				continue;
292			return RX_HANDLER_CONSUMED;
293		default: /* STOLEN */
294			return RX_HANDLER_CONSUMED;
295		}
296	}
297frame_finish:
298	net = dev_net(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 */
309static 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 */
325static 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(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, false);
343
344	p = br_port_get_rcu(skb->dev);
345	if (p->flags & BR_VLAN_TUNNEL)
346		br_handle_ingress_vlan_tunnel(skb, p, 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(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
402			    dev_net(skb->dev), NULL, skb, skb->dev, NULL,
403			    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
413forward:
414	if (br_mst_is_enabled(p->br))
415		goto defer_stp_filtering;
416
417	switch (p->state) {
418	case BR_STATE_FORWARDING:
419	case BR_STATE_LEARNING:
420defer_stp_filtering:
421		if (ether_addr_equal(p->br->dev->dev_addr, dest))
422			skb->pkt_type = PACKET_HOST;
423
424		return nf_hook_bridge_pre(skb, pskb);
425	default:
426drop:
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 */
439static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb)
440{
441	return RX_HANDLER_PASS;
442}
443
444rx_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
452void br_add_frame(struct net_bridge *br, struct br_frame_type *ft)
453{
454	hlist_add_head_rcu(&ft->list, &br->frame_type_list);
455}
456
457void 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(&ft->list);
464			return;
465		}
466}
467