br_input.c 7.8 KB
Newer Older
L
Linus Torvalds 已提交
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>
L
Linus Torvalds 已提交
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>
L
Linus Torvalds 已提交
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 31 32 33
static int br_netif_receive_skb(struct sock *sk, struct sk_buff *skb)
{
	return netif_receive_skb(skb);
}

34
static int br_pass_frame_up(struct sk_buff *skb)
L
Linus Torvalds 已提交
35
{
36
	struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
37
	struct net_bridge *br = netdev_priv(brdev);
38
	struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
39
	struct net_port_vlans *pv;
L
Linus Torvalds 已提交
40

E
Eric Dumazet 已提交
41
	u64_stats_update_begin(&brstats->syncp);
42 43
	brstats->rx_packets++;
	brstats->rx_bytes += skb->len;
E
Eric Dumazet 已提交
44
	u64_stats_update_end(&brstats->syncp);
L
Linus Torvalds 已提交
45

46 47 48 49
	/* Bridge is just like any other port.  Make sure the
	 * packet is allowed except in promisc modue when someone
	 * may be running packet capture.
	 */
50
	pv = br_get_vlan_info(br);
51
	if (!(brdev->flags & IFF_PROMISC) &&
52
	    !br_allowed_egress(br, pv, skb)) {
53 54 55 56
		kfree_skb(skb);
		return NET_RX_DROP;
	}

L
Linus Torvalds 已提交
57
	indev = skb->dev;
58
	skb->dev = brdev;
59 60 61
	skb = br_handle_vlan(br, pv, skb);
	if (!skb)
		return NET_RX_DROP;
L
Linus Torvalds 已提交
62

63 64
	return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
		       dev_net(indev), NULL, skb, indev, NULL,
65
		       br_netif_receive_skb);
L
Linus Torvalds 已提交
66 67
}

68
static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br,
69
			    u16 vid, struct net_bridge_port *p)
70 71 72 73 74 75 76
{
	struct net_device *dev = br->dev;
	struct neighbour *n;
	struct arphdr *parp;
	u8 *arpptr, *sha;
	__be32 sip, tip;

77 78
	BR_INPUT_SKB_CB(skb)->proxyarp_replied = false;

79 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
	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);
116 117
		if (f && ((p->flags & BR_PROXYARP) ||
			  (f->dst && (f->dst->flags & BR_PROXYARP_WIFI)))) {
118 119
			arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip,
				 sha, n->ha, sha);
120 121
			BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
		}
122 123 124 125 126

		neigh_release(n);
	}
}

127
/* note: already called with rcu_read_lock */
128
int br_handle_frame_finish(struct sock *sk, struct sk_buff *skb)
L
Linus Torvalds 已提交
129 130
{
	const unsigned char *dest = eth_hdr(skb)->h_dest;
131
	struct net_bridge_port *p = br_port_get_rcu(skb->dev);
132
	struct net_bridge *br;
L
Linus Torvalds 已提交
133
	struct net_bridge_fdb_entry *dst;
134
	struct net_bridge_mdb_entry *mdst;
135
	struct sk_buff *skb2;
136
	bool unicast = true;
137
	u16 vid = 0;
L
Linus Torvalds 已提交
138

139 140 141
	if (!p || p->state == BR_STATE_DISABLED)
		goto drop;

142
	if (!br_allowed_ingress(p->br, nbp_get_vlan_info(p), skb, &vid))
143
		goto out;
144

145
	/* insert into forwarding database after filtering to avoid spoofing */
146
	br = p->br;
147
	if (p->flags & BR_LEARNING)
148
		br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false);
149

150
	if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) &&
151
	    br_multicast_rcv(br, p, skb, vid))
152 153
		goto drop;

154 155
	if (p->state == BR_STATE_LEARNING)
		goto drop;
156

157 158
	BR_INPUT_SKB_CB(skb)->brdev = br->dev;

159 160
	/* The packet skb2 goes to the local host (NULL to skip). */
	skb2 = NULL;
L
Linus Torvalds 已提交
161

162 163 164 165
	if (br->dev->flags & IFF_PROMISC)
		skb2 = skb;

	dst = NULL;
L
Linus Torvalds 已提交
166

167 168
	if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP))
		br_do_proxy_arp(skb, br, vid, p);
169

170
	if (is_broadcast_ether_addr(dest)) {
171
		skb2 = skb;
172 173
		unicast = false;
	} else if (is_multicast_ether_addr(dest)) {
174
		mdst = br_mdb_get(br, skb, vid);
175
		if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
176
		    br_multicast_querier_exists(br, eth_hdr(skb))) {
177
			if ((mdst && mdst->mglist) ||
178 179 180 181 182 183 184 185 186
			    br_multicast_is_router(br))
				skb2 = skb;
			br_multicast_forward(mdst, skb, skb2);
			skb = NULL;
			if (!skb2)
				goto out;
		} else
			skb2 = skb;

187
		unicast = false;
188
		br->dev->stats.multicast++;
189 190
	} else if ((dst = __br_fdb_get(br, dest, vid)) &&
			dst->is_local) {
191 192 193
		skb2 = skb;
		/* Do not forward the packet since it's local. */
		skb = NULL;
L
Linus Torvalds 已提交
194 195
	}

196
	if (skb) {
197 198
		if (dst) {
			dst->used = jiffies;
199
			br_forward(dst->dst, skb, skb2);
200
		} else
201
			br_flood_forward(br, skb, skb2, unicast);
202
	}
L
Linus Torvalds 已提交
203

204
	if (skb2)
205
		return br_pass_frame_up(skb2);
206

L
Linus Torvalds 已提交
207 208
out:
	return 0;
209 210 211
drop:
	kfree_skb(skb);
	goto out;
L
Linus Torvalds 已提交
212
}
213
EXPORT_SYMBOL_GPL(br_handle_frame_finish);
L
Linus Torvalds 已提交
214

215
/* note: already called with rcu_read_lock */
216
static int br_handle_local_finish(struct sock *sk, struct sk_buff *skb)
217
{
218
	struct net_bridge_port *p = br_port_get_rcu(skb->dev);
219
	u16 vid = 0;
220

221 222
	/* check if vlan is allowed, to avoid spoofing */
	if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid))
223
		br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false);
224 225 226
	return 0;	 /* process further */
}

L
Linus Torvalds 已提交
227
/*
228
 * Return NULL if skb is handled
229
 * note: already called with rcu_read_lock
L
Linus Torvalds 已提交
230
 */
231
rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
L
Linus Torvalds 已提交
232
{
233
	struct net_bridge_port *p;
234
	struct sk_buff *skb = *pskb;
L
Linus Torvalds 已提交
235
	const unsigned char *dest = eth_hdr(skb)->h_dest;
236
	br_should_route_hook_t *rhook;
L
Linus Torvalds 已提交
237

238
	if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
239
		return RX_HANDLER_PASS;
240

L
Linus Torvalds 已提交
241
	if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
242
		goto drop;
L
Linus Torvalds 已提交
243

H
Herbert Xu 已提交
244 245
	skb = skb_share_check(skb, GFP_ATOMIC);
	if (!skb)
246
		return RX_HANDLER_CONSUMED;
H
Herbert Xu 已提交
247

248
	p = br_port_get_rcu(skb->dev);
249

250
	if (unlikely(is_link_local_ether_addr(dest))) {
251 252
		u16 fwd_mask = p->br->group_fwd_mask_required;

253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269
		/*
		 * 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 */
270 271
			if (p->br->stp_enabled == BR_NO_STP ||
			    fwd_mask & (1u << dest[5]))
272 273 274 275
				goto forward;
			break;

		case 0x01:	/* IEEE MAC (Pause) */
S
Stephen Hemminger 已提交
276 277
			goto drop;

278 279
		default:
			/* Allow selective forwarding for most other protocols */
280 281
			fwd_mask |= p->br->group_fwd_mask;
			if (fwd_mask & (1u << dest[5]))
282 283
				goto forward;
		}
284

285
		/* Deliver packet to local host only */
286 287 288
		if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
			    dev_net(skb->dev), NULL, skb, skb->dev, NULL,
			    br_handle_local_finish)) {
289 290 291 292 293
			return RX_HANDLER_CONSUMED; /* consumed by filter */
		} else {
			*pskb = skb;
			return RX_HANDLER_PASS;	/* continue processing */
		}
S
Stephen Hemminger 已提交
294
	}
L
Linus Torvalds 已提交
295

296
forward:
297 298
	switch (p->state) {
	case BR_STATE_FORWARDING:
299
		rhook = rcu_dereference(br_should_route_hook);
300
		if (rhook) {
301 302 303 304
			if ((*rhook)(skb)) {
				*pskb = skb;
				return RX_HANDLER_PASS;
			}
L
Linus Torvalds 已提交
305 306
			dest = eth_hdr(skb)->h_dest;
		}
307 308
		/* fall through */
	case BR_STATE_LEARNING:
309
		if (ether_addr_equal(p->br->dev->dev_addr, dest))
L
Linus Torvalds 已提交
310 311
			skb->pkt_type = PACKET_HOST;

312 313
		NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING,
			dev_net(skb->dev), NULL, skb, skb->dev, NULL,
L
Linus Torvalds 已提交
314
			br_handle_frame_finish);
315 316 317 318
		break;
	default:
drop:
		kfree_skb(skb);
L
Linus Torvalds 已提交
319
	}
320
	return RX_HANDLER_CONSUMED;
L
Linus Torvalds 已提交
321
}