1 /*
2 * Handle incoming frames
3 * Linux ethernet bridge
4 *
5 * Authors:
6 * Lennert Buytenhek <buytenh@gnu.org>
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version
11 * 2 of the License, or (at your option) any later version.
12 */
13
14 #include <linux/slab.h>
15 #include <linux/kernel.h>
16 #include <linux/netdevice.h>
17 #include <linux/etherdevice.h>
18 #include <linux/netfilter_bridge.h>
19 #include <linux/export.h>
20 #include <linux/rculist.h>
21 #include "br_private.h"
22
23 /* Hook for brouter */
24 br_should_route_hook_t __rcu *br_should_route_hook __read_mostly;
25 EXPORT_SYMBOL(br_should_route_hook);
26
br_pass_frame_up(struct sk_buff * skb)27 static int br_pass_frame_up(struct sk_buff *skb)
28 {
29 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
30 struct net_bridge *br = netdev_priv(brdev);
31 struct br_cpu_netstats *brstats = this_cpu_ptr(br->stats);
32
33 u64_stats_update_begin(&brstats->syncp);
34 brstats->rx_packets++;
35 brstats->rx_bytes += skb->len;
36 u64_stats_update_end(&brstats->syncp);
37
38 /* Bridge is just like any other port. Make sure the
39 * packet is allowed except in promisc modue when someone
40 * may be running packet capture.
41 */
42 if (!(brdev->flags & IFF_PROMISC) &&
43 !br_allowed_egress(br, br_get_vlan_info(br), skb)) {
44 kfree_skb(skb);
45 return NET_RX_DROP;
46 }
47
48 skb = br_handle_vlan(br, br_get_vlan_info(br), skb);
49 if (!skb)
50 return NET_RX_DROP;
51
52 indev = skb->dev;
53 skb->dev = brdev;
54
55 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL,
56 netif_receive_skb);
57 }
58
59 /* note: already called with rcu_read_lock */
br_handle_frame_finish(struct sk_buff * skb)60 int br_handle_frame_finish(struct sk_buff *skb)
61 {
62 const unsigned char *dest = eth_hdr(skb)->h_dest;
63 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
64 struct net_bridge *br;
65 struct net_bridge_fdb_entry *dst;
66 struct net_bridge_mdb_entry *mdst;
67 struct sk_buff *skb2;
68 u16 vid = 0;
69
70 if (!p || p->state == BR_STATE_DISABLED)
71 goto drop;
72
73 if (!br_allowed_ingress(p->br, nbp_get_vlan_info(p), skb, &vid))
74 goto drop;
75
76 /* insert into forwarding database after filtering to avoid spoofing */
77 br = p->br;
78 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid);
79
80 if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) &&
81 br_multicast_rcv(br, p, skb))
82 goto drop;
83
84 if (p->state == BR_STATE_LEARNING)
85 goto drop;
86
87 BR_INPUT_SKB_CB(skb)->brdev = br->dev;
88
89 /* The packet skb2 goes to the local host (NULL to skip). */
90 skb2 = NULL;
91
92 if (br->dev->flags & IFF_PROMISC)
93 skb2 = skb;
94
95 dst = NULL;
96
97 if (is_broadcast_ether_addr(dest))
98 skb2 = skb;
99 else if (is_multicast_ether_addr(dest)) {
100 mdst = br_mdb_get(br, skb, vid);
101 if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) {
102 if ((mdst && mdst->mglist) ||
103 br_multicast_is_router(br))
104 skb2 = skb;
105 br_multicast_forward(mdst, skb, skb2);
106 skb = NULL;
107 if (!skb2)
108 goto out;
109 } else
110 skb2 = skb;
111
112 br->dev->stats.multicast++;
113 } else if ((dst = __br_fdb_get(br, dest, vid)) &&
114 dst->is_local) {
115 skb2 = skb;
116 /* Do not forward the packet since it's local. */
117 skb = NULL;
118 }
119
120 if (skb) {
121 if (dst) {
122 dst->used = jiffies;
123 br_forward(dst->dst, skb, skb2);
124 } else
125 br_flood_forward(br, skb, skb2);
126 }
127
128 if (skb2)
129 return br_pass_frame_up(skb2);
130
131 out:
132 return 0;
133 drop:
134 kfree_skb(skb);
135 goto out;
136 }
137
138 /* note: already called with rcu_read_lock */
br_handle_local_finish(struct sk_buff * skb)139 static int br_handle_local_finish(struct sk_buff *skb)
140 {
141 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
142 u16 vid = 0;
143
144 br_vlan_get_tag(skb, &vid);
145 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid);
146 return 0; /* process further */
147 }
148
149 /*
150 * Return NULL if skb is handled
151 * note: already called with rcu_read_lock
152 */
br_handle_frame(struct sk_buff ** pskb)153 rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
154 {
155 struct net_bridge_port *p;
156 struct sk_buff *skb = *pskb;
157 const unsigned char *dest = eth_hdr(skb)->h_dest;
158 br_should_route_hook_t *rhook;
159
160 if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
161 return RX_HANDLER_PASS;
162
163 if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
164 goto drop;
165
166 skb = skb_share_check(skb, GFP_ATOMIC);
167 if (!skb)
168 return RX_HANDLER_CONSUMED;
169
170 p = br_port_get_rcu(skb->dev);
171
172 if (unlikely(is_link_local_ether_addr(dest))) {
173 /*
174 * See IEEE 802.1D Table 7-10 Reserved addresses
175 *
176 * Assignment Value
177 * Bridge Group Address 01-80-C2-00-00-00
178 * (MAC Control) 802.3 01-80-C2-00-00-01
179 * (Link Aggregation) 802.3 01-80-C2-00-00-02
180 * 802.1X PAE address 01-80-C2-00-00-03
181 *
182 * 802.1AB LLDP 01-80-C2-00-00-0E
183 *
184 * Others reserved for future standardization
185 */
186 switch (dest[5]) {
187 case 0x00: /* Bridge Group Address */
188 /* If STP is turned off,
189 then must forward to keep loop detection */
190 if (p->br->stp_enabled == BR_NO_STP)
191 goto forward;
192 break;
193
194 case 0x01: /* IEEE MAC (Pause) */
195 goto drop;
196
197 default:
198 /* Allow selective forwarding for most other protocols */
199 if (p->br->group_fwd_mask & (1u << dest[5]))
200 goto forward;
201 }
202
203 /* Deliver packet to local host only */
204 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
205 NULL, br_handle_local_finish)) {
206 return RX_HANDLER_CONSUMED; /* consumed by filter */
207 } else {
208 *pskb = skb;
209 return RX_HANDLER_PASS; /* continue processing */
210 }
211 }
212
213 forward:
214 switch (p->state) {
215 case BR_STATE_FORWARDING:
216 rhook = rcu_dereference(br_should_route_hook);
217 if (rhook) {
218 if ((*rhook)(skb)) {
219 *pskb = skb;
220 return RX_HANDLER_PASS;
221 }
222 dest = eth_hdr(skb)->h_dest;
223 }
224 /* fall through */
225 case BR_STATE_LEARNING:
226 if (ether_addr_equal(p->br->dev->dev_addr, dest))
227 skb->pkt_type = PACKET_HOST;
228
229 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
230 br_handle_frame_finish);
231 break;
232 default:
233 drop:
234 kfree_skb(skb);
235 }
236 return RX_HANDLER_CONSUMED;
237 }
238