br_input.c 7.84 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1
2
3
4
5
6
7
8
9
10
11
12
13
/*
 *	Handle incoming frames
 *	Linux ethernet bridge
 *
 *	Authors:
 *	Lennert Buytenhek		<buytenh@gnu.org>
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 */

14
#include <linux/slab.h>
Linus Torvalds's avatar
Linus Torvalds committed
15
16
17
18
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/netfilter_bridge.h>
19
20
#include <linux/neighbour.h>
#include <net/arp.h>
21
#include <linux/export.h>
22
#include <linux/rculist.h>
Linus Torvalds's avatar
Linus Torvalds committed
23
24
#include "br_private.h"

25
26
27
28
/* Hook for brouter */
br_should_route_hook_t __rcu *br_should_route_hook __read_mostly;
EXPORT_SYMBOL(br_should_route_hook);

29
30
static int
br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
31
32
33
34
{
	return netif_receive_skb(skb);
}

35
static int br_pass_frame_up(struct sk_buff *skb)
Linus Torvalds's avatar
Linus Torvalds committed
36
{
37
	struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
38
	struct net_bridge *br = netdev_priv(brdev);
39
	struct net_bridge_vlan_group *vg;
40
	struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
Linus Torvalds's avatar
Linus Torvalds committed
41

Eric Dumazet's avatar
Eric Dumazet committed
42
	u64_stats_update_begin(&brstats->syncp);
43
44
	brstats->rx_packets++;
	brstats->rx_bytes += skb->len;
Eric Dumazet's avatar
Eric Dumazet committed
45
	u64_stats_update_end(&brstats->syncp);
Linus Torvalds's avatar
Linus Torvalds committed
46

47
	vg = br_vlan_group(br);
48
49
50
51
52
	/* Bridge is just like any other port.  Make sure the
	 * packet is allowed except in promisc modue when someone
	 * may be running packet capture.
	 */
	if (!(brdev->flags & IFF_PROMISC) &&
53
	    !br_allowed_egress(vg, skb)) {
54
55
56
57
		kfree_skb(skb);
		return NET_RX_DROP;
	}

Linus Torvalds's avatar
Linus Torvalds committed
58
	indev = skb->dev;
59
	skb->dev = brdev;
60
	skb = br_handle_vlan(br, vg, skb);
61
62
	if (!skb)
		return NET_RX_DROP;
Linus Torvalds's avatar
Linus Torvalds committed
63

64
65
	return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
		       dev_net(indev), NULL, skb, indev, NULL,
66
		       br_netif_receive_skb);
Linus Torvalds's avatar
Linus Torvalds committed
67
68
}

69
static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br,
70
			    u16 vid, struct net_bridge_port *p)
71
72
73
74
75
76
77
{
	struct net_device *dev = br->dev;
	struct neighbour *n;
	struct arphdr *parp;
	u8 *arpptr, *sha;
	__be32 sip, tip;

78
79
	BR_INPUT_SKB_CB(skb)->proxyarp_replied = false;

80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
	if (dev->flags & IFF_NOARP)
		return;

	if (!pskb_may_pull(skb, arp_hdr_len(dev))) {
		dev->stats.tx_dropped++;
		return;
	}
	parp = arp_hdr(skb);

	if (parp->ar_pro != htons(ETH_P_IP) ||
	    parp->ar_op != htons(ARPOP_REQUEST) ||
	    parp->ar_hln != dev->addr_len ||
	    parp->ar_pln != 4)
		return;

	arpptr = (u8 *)parp + sizeof(struct arphdr);
	sha = arpptr;
	arpptr += dev->addr_len;	/* sha */
	memcpy(&sip, arpptr, sizeof(sip));
	arpptr += sizeof(sip);
	arpptr += dev->addr_len;	/* tha */
	memcpy(&tip, arpptr, sizeof(tip));

	if (ipv4_is_loopback(tip) ||
	    ipv4_is_multicast(tip))
		return;

	n = neigh_lookup(&arp_tbl, &tip, dev);
	if (n) {
		struct net_bridge_fdb_entry *f;

		if (!(n->nud_state & NUD_VALID)) {
			neigh_release(n);
			return;
		}

		f = __br_fdb_get(br, n->ha, vid);
117
118
		if (f && ((p->flags & BR_PROXYARP) ||
			  (f->dst && (f->dst->flags & BR_PROXYARP_WIFI)))) {
119
120
			arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip,
				 sha, n->ha, sha);
121
122
			BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
		}
123
124
125
126
127

		neigh_release(n);
	}
}

128
/* note: already called with rcu_read_lock */
129
int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
Linus Torvalds's avatar
Linus Torvalds committed
130
131
{
	const unsigned char *dest = eth_hdr(skb)->h_dest;
132
	struct net_bridge_port *p = br_port_get_rcu(skb->dev);
133
	struct net_bridge *br;
Linus Torvalds's avatar
Linus Torvalds committed
134
	struct net_bridge_fdb_entry *dst;
135
	struct net_bridge_mdb_entry *mdst;
136
	struct sk_buff *skb2;
137
	bool unicast = true;
138
	u16 vid = 0;
Linus Torvalds's avatar
Linus Torvalds committed
139

140
141
142
	if (!p || p->state == BR_STATE_DISABLED)
		goto drop;

143
	if (!nbp_allowed_ingress(p, skb, &vid))
144
		goto out;
145

146
	/* insert into forwarding database after filtering to avoid spoofing */
147
	br = p->br;
148
	if (p->flags & BR_LEARNING)
149
		br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false);
150

151
	if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) &&
152
	    br_multicast_rcv(br, p, skb, vid))
153
154
		goto drop;

155
156
	if (p->state == BR_STATE_LEARNING)
		goto drop;
157

158
159
	BR_INPUT_SKB_CB(skb)->brdev = br->dev;

160
161
	/* The packet skb2 goes to the local host (NULL to skip). */
	skb2 = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
162

163
164
165
166
	if (br->dev->flags & IFF_PROMISC)
		skb2 = skb;

	dst = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
167

168
169
	if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP))
		br_do_proxy_arp(skb, br, vid, p);
170

171
	if (is_broadcast_ether_addr(dest)) {
172
		skb2 = skb;
173
174
		unicast = false;
	} else if (is_multicast_ether_addr(dest)) {
175
		mdst = br_mdb_get(br, skb, vid);
176
		if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
177
		    br_multicast_querier_exists(br, eth_hdr(skb))) {
178
			if ((mdst && mdst->mglist) ||
179
180
181
182
183
184
185
186
187
			    br_multicast_is_router(br))
				skb2 = skb;
			br_multicast_forward(mdst, skb, skb2);
			skb = NULL;
			if (!skb2)
				goto out;
		} else
			skb2 = skb;

188
		unicast = false;
189
		br->dev->stats.multicast++;
190
191
	} else if ((dst = __br_fdb_get(br, dest, vid)) &&
			dst->is_local) {
192
193
194
		skb2 = skb;
		/* Do not forward the packet since it's local. */
		skb = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
195
196
	}

197
	if (skb) {
198
199
		if (dst) {
			dst->used = jiffies;
200
			br_forward(dst->dst, skb, skb2);
201
		} else
202
			br_flood_forward(br, skb, skb2, unicast);
203
	}
Linus Torvalds's avatar
Linus Torvalds committed
204

205
	if (skb2)
206
		return br_pass_frame_up(skb2);
207

Linus Torvalds's avatar
Linus Torvalds committed
208
209
out:
	return 0;
210
211
212
drop:
	kfree_skb(skb);
	goto out;
Linus Torvalds's avatar
Linus Torvalds committed
213
}
214
EXPORT_SYMBOL_GPL(br_handle_frame_finish);
Linus Torvalds's avatar
Linus Torvalds committed
215

216
/* note: already called with rcu_read_lock */
217
static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
218
{
219
	struct net_bridge_port *p = br_port_get_rcu(skb->dev);
220
	u16 vid = 0;
221

222
223
	/* check if vlan is allowed, to avoid spoofing */
	if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid))
224
		br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false);
225
226
227
	return 0;	 /* process further */
}

Linus Torvalds's avatar
Linus Torvalds committed
228
/*
229
 * Return NULL if skb is handled
230
 * note: already called with rcu_read_lock
Linus Torvalds's avatar
Linus Torvalds committed
231
 */
232
rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
Linus Torvalds's avatar
Linus Torvalds committed
233
{
234
	struct net_bridge_port *p;
235
	struct sk_buff *skb = *pskb;
Linus Torvalds's avatar
Linus Torvalds committed
236
	const unsigned char *dest = eth_hdr(skb)->h_dest;
237
	br_should_route_hook_t *rhook;
Linus Torvalds's avatar
Linus Torvalds committed
238

239
	if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
240
		return RX_HANDLER_PASS;
241

Linus Torvalds's avatar
Linus Torvalds committed
242
	if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
243
		goto drop;
Linus Torvalds's avatar
Linus Torvalds committed
244

Herbert Xu's avatar
Herbert Xu committed
245
246
	skb = skb_share_check(skb, GFP_ATOMIC);
	if (!skb)
247
		return RX_HANDLER_CONSUMED;
Herbert Xu's avatar
Herbert Xu committed
248

249
	p = br_port_get_rcu(skb->dev);
250

251
	if (unlikely(is_link_local_ether_addr(dest))) {
252
253
		u16 fwd_mask = p->br->group_fwd_mask_required;

254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
		/*
		 * See IEEE 802.1D Table 7-10 Reserved addresses
		 *
		 * Assignment		 		Value
		 * Bridge Group Address		01-80-C2-00-00-00
		 * (MAC Control) 802.3		01-80-C2-00-00-01
		 * (Link Aggregation) 802.3	01-80-C2-00-00-02
		 * 802.1X PAE address		01-80-C2-00-00-03
		 *
		 * 802.1AB LLDP 		01-80-C2-00-00-0E
		 *
		 * Others reserved for future standardization
		 */
		switch (dest[5]) {
		case 0x00:	/* Bridge Group Address */
			/* If STP is turned off,
			   then must forward to keep loop detection */
271
272
			if (p->br->stp_enabled == BR_NO_STP ||
			    fwd_mask & (1u << dest[5]))
273
274
275
276
				goto forward;
			break;

		case 0x01:	/* IEEE MAC (Pause) */
277
278
			goto drop;

279
280
		default:
			/* Allow selective forwarding for most other protocols */
281
282
			fwd_mask |= p->br->group_fwd_mask;
			if (fwd_mask & (1u << dest[5]))
283
284
				goto forward;
		}
285

286
		/* Deliver packet to local host only */
287
288
289
		if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
			    dev_net(skb->dev), NULL, skb, skb->dev, NULL,
			    br_handle_local_finish)) {
290
291
292
293
294
			return RX_HANDLER_CONSUMED; /* consumed by filter */
		} else {
			*pskb = skb;
			return RX_HANDLER_PASS;	/* continue processing */
		}
295
	}
Linus Torvalds's avatar
Linus Torvalds committed
296

297
forward:
298
299
	switch (p->state) {
	case BR_STATE_FORWARDING:
300
		rhook = rcu_dereference(br_should_route_hook);
301
		if (rhook) {
302
303
304
305
			if ((*rhook)(skb)) {
				*pskb = skb;
				return RX_HANDLER_PASS;
			}
Linus Torvalds's avatar
Linus Torvalds committed
306
307
			dest = eth_hdr(skb)->h_dest;
		}
308
309
		/* fall through */
	case BR_STATE_LEARNING:
310
		if (ether_addr_equal(p->br->dev->dev_addr, dest))
Linus Torvalds's avatar
Linus Torvalds committed
311
312
			skb->pkt_type = PACKET_HOST;

313
314
		NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING,
			dev_net(skb->dev), NULL, skb, skb->dev, NULL,
Linus Torvalds's avatar
Linus Torvalds committed
315
			br_handle_frame_finish);
316
317
318
319
		break;
	default:
drop:
		kfree_skb(skb);
Linus Torvalds's avatar
Linus Torvalds committed
320
	}
321
	return RX_HANDLER_CONSUMED;
Linus Torvalds's avatar
Linus Torvalds committed
322
}