Loading...
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 "br_private.h"
20
21/* Bridge group multicast address 802.1d (pg 51). */
22const u8 br_group_address[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 };
23
24/* Hook for brouter */
25br_should_route_hook_t __rcu *br_should_route_hook __read_mostly;
26EXPORT_SYMBOL(br_should_route_hook);
27
28static int br_pass_frame_up(struct sk_buff *skb)
29{
30 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
31 struct net_bridge *br = netdev_priv(brdev);
32 struct br_cpu_netstats *brstats = this_cpu_ptr(br->stats);
33
34 u64_stats_update_begin(&brstats->syncp);
35 brstats->rx_packets++;
36 brstats->rx_bytes += skb->len;
37 u64_stats_update_end(&brstats->syncp);
38
39 indev = skb->dev;
40 skb->dev = brdev;
41
42 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL,
43 netif_receive_skb);
44}
45
46/* note: already called with rcu_read_lock */
47int br_handle_frame_finish(struct sk_buff *skb)
48{
49 const unsigned char *dest = eth_hdr(skb)->h_dest;
50 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
51 struct net_bridge *br;
52 struct net_bridge_fdb_entry *dst;
53 struct net_bridge_mdb_entry *mdst;
54 struct sk_buff *skb2;
55
56 if (!p || p->state == BR_STATE_DISABLED)
57 goto drop;
58
59 /* insert into forwarding database after filtering to avoid spoofing */
60 br = p->br;
61 br_fdb_update(br, p, eth_hdr(skb)->h_source);
62
63 if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) &&
64 br_multicast_rcv(br, p, skb))
65 goto drop;
66
67 if (p->state == BR_STATE_LEARNING)
68 goto drop;
69
70 BR_INPUT_SKB_CB(skb)->brdev = br->dev;
71
72 /* The packet skb2 goes to the local host (NULL to skip). */
73 skb2 = NULL;
74
75 if (br->dev->flags & IFF_PROMISC)
76 skb2 = skb;
77
78 dst = NULL;
79
80 if (is_broadcast_ether_addr(dest))
81 skb2 = skb;
82 else if (is_multicast_ether_addr(dest)) {
83 mdst = br_mdb_get(br, skb);
84 if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) {
85 if ((mdst && mdst->mglist) ||
86 br_multicast_is_router(br))
87 skb2 = skb;
88 br_multicast_forward(mdst, skb, skb2);
89 skb = NULL;
90 if (!skb2)
91 goto out;
92 } else
93 skb2 = skb;
94
95 br->dev->stats.multicast++;
96 } else if ((dst = __br_fdb_get(br, dest)) && dst->is_local) {
97 skb2 = skb;
98 /* Do not forward the packet since it's local. */
99 skb = NULL;
100 }
101
102 if (skb) {
103 if (dst) {
104 dst->used = jiffies;
105 br_forward(dst->dst, skb, skb2);
106 } else
107 br_flood_forward(br, skb, skb2);
108 }
109
110 if (skb2)
111 return br_pass_frame_up(skb2);
112
113out:
114 return 0;
115drop:
116 kfree_skb(skb);
117 goto out;
118}
119
120/* note: already called with rcu_read_lock */
121static int br_handle_local_finish(struct sk_buff *skb)
122{
123 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
124
125 br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
126 return 0; /* process further */
127}
128
129/* Does address match the link local multicast address.
130 * 01:80:c2:00:00:0X
131 */
132static inline int is_link_local(const unsigned char *dest)
133{
134 __be16 *a = (__be16 *)dest;
135 static const __be16 *b = (const __be16 *)br_group_address;
136 static const __be16 m = cpu_to_be16(0xfff0);
137
138 return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0;
139}
140
141/*
142 * Return NULL if skb is handled
143 * note: already called with rcu_read_lock
144 */
145rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
146{
147 struct net_bridge_port *p;
148 struct sk_buff *skb = *pskb;
149 const unsigned char *dest = eth_hdr(skb)->h_dest;
150 br_should_route_hook_t *rhook;
151
152 if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
153 return RX_HANDLER_PASS;
154
155 if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
156 goto drop;
157
158 skb = skb_share_check(skb, GFP_ATOMIC);
159 if (!skb)
160 return RX_HANDLER_CONSUMED;
161
162 p = br_port_get_rcu(skb->dev);
163
164 if (unlikely(is_link_local(dest))) {
165 /* Pause frames shouldn't be passed up by driver anyway */
166 if (skb->protocol == htons(ETH_P_PAUSE))
167 goto drop;
168
169 /* If STP is turned off, then forward */
170 if (p->br->stp_enabled == BR_NO_STP && dest[5] == 0)
171 goto forward;
172
173 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
174 NULL, br_handle_local_finish)) {
175 return RX_HANDLER_CONSUMED; /* consumed by filter */
176 } else {
177 *pskb = skb;
178 return RX_HANDLER_PASS; /* continue processing */
179 }
180 }
181
182forward:
183 switch (p->state) {
184 case BR_STATE_FORWARDING:
185 rhook = rcu_dereference(br_should_route_hook);
186 if (rhook) {
187 if ((*rhook)(skb)) {
188 *pskb = skb;
189 return RX_HANDLER_PASS;
190 }
191 dest = eth_hdr(skb)->h_dest;
192 }
193 /* fall through */
194 case BR_STATE_LEARNING:
195 if (!compare_ether_addr(p->br->dev->dev_addr, dest))
196 skb->pkt_type = PACKET_HOST;
197
198 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
199 br_handle_frame_finish);
200 break;
201 default:
202drop:
203 kfree_skb(skb);
204 }
205 return RX_HANDLER_CONSUMED;
206}
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/neighbour.h>
20#include <net/arp.h>
21#include <linux/export.h>
22#include <linux/rculist.h>
23#include "br_private.h"
24#include "br_private_tunnel.h"
25
26/* Hook for brouter */
27br_should_route_hook_t __rcu *br_should_route_hook __read_mostly;
28EXPORT_SYMBOL(br_should_route_hook);
29
30static int
31br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
32{
33 br_drop_fake_rtable(skb);
34 return netif_receive_skb(skb);
35}
36
37static int br_pass_frame_up(struct sk_buff *skb)
38{
39 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
40 struct net_bridge *br = netdev_priv(brdev);
41 struct net_bridge_vlan_group *vg;
42 struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
43
44 u64_stats_update_begin(&brstats->syncp);
45 brstats->rx_packets++;
46 brstats->rx_bytes += skb->len;
47 u64_stats_update_end(&brstats->syncp);
48
49 vg = br_vlan_group_rcu(br);
50 /* Bridge is just like any other port. Make sure the
51 * packet is allowed except in promisc modue when someone
52 * may be running packet capture.
53 */
54 if (!(brdev->flags & IFF_PROMISC) &&
55 !br_allowed_egress(vg, skb)) {
56 kfree_skb(skb);
57 return NET_RX_DROP;
58 }
59
60 indev = skb->dev;
61 skb->dev = brdev;
62 skb = br_handle_vlan(br, NULL, vg, skb);
63 if (!skb)
64 return NET_RX_DROP;
65 /* update the multicast stats if the packet is IGMP/MLD */
66 br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb),
67 BR_MCAST_DIR_TX);
68
69 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
70 dev_net(indev), NULL, skb, indev, NULL,
71 br_netif_receive_skb);
72}
73
74/* note: already called with rcu_read_lock */
75int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
76{
77 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
78 enum br_pkt_type pkt_type = BR_PKT_UNICAST;
79 struct net_bridge_fdb_entry *dst = NULL;
80 struct net_bridge_mdb_entry *mdst;
81 bool local_rcv, mcast_hit = false;
82 const unsigned char *dest;
83 struct net_bridge *br;
84 u16 vid = 0;
85
86 if (!p || p->state == BR_STATE_DISABLED)
87 goto drop;
88
89 if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid))
90 goto out;
91
92 nbp_switchdev_frame_mark(p, skb);
93
94 /* insert into forwarding database after filtering to avoid spoofing */
95 br = p->br;
96 if (p->flags & BR_LEARNING)
97 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false);
98
99 local_rcv = !!(br->dev->flags & IFF_PROMISC);
100 dest = eth_hdr(skb)->h_dest;
101 if (is_multicast_ether_addr(dest)) {
102 /* by definition the broadcast is also a multicast address */
103 if (is_broadcast_ether_addr(dest)) {
104 pkt_type = BR_PKT_BROADCAST;
105 local_rcv = true;
106 } else {
107 pkt_type = BR_PKT_MULTICAST;
108 if (br_multicast_rcv(br, p, skb, vid))
109 goto drop;
110 }
111 }
112
113 if (p->state == BR_STATE_LEARNING)
114 goto drop;
115
116 BR_INPUT_SKB_CB(skb)->brdev = br->dev;
117
118 if (IS_ENABLED(CONFIG_INET) &&
119 (skb->protocol == htons(ETH_P_ARP) ||
120 skb->protocol == htons(ETH_P_RARP))) {
121 br_do_proxy_suppress_arp(skb, br, vid, p);
122 } else if (IS_ENABLED(CONFIG_IPV6) &&
123 skb->protocol == htons(ETH_P_IPV6) &&
124 br->neigh_suppress_enabled &&
125 pskb_may_pull(skb, sizeof(struct ipv6hdr) +
126 sizeof(struct nd_msg)) &&
127 ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) {
128 struct nd_msg *msg, _msg;
129
130 msg = br_is_nd_neigh_msg(skb, &_msg);
131 if (msg)
132 br_do_suppress_nd(skb, br, vid, p, msg);
133 }
134
135 switch (pkt_type) {
136 case BR_PKT_MULTICAST:
137 mdst = br_mdb_get(br, skb, vid);
138 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
139 br_multicast_querier_exists(br, eth_hdr(skb))) {
140 if ((mdst && mdst->host_joined) ||
141 br_multicast_is_router(br)) {
142 local_rcv = true;
143 br->dev->stats.multicast++;
144 }
145 mcast_hit = true;
146 } else {
147 local_rcv = true;
148 br->dev->stats.multicast++;
149 }
150 break;
151 case BR_PKT_UNICAST:
152 dst = br_fdb_find_rcu(br, dest, vid);
153 default:
154 break;
155 }
156
157 if (dst) {
158 unsigned long now = jiffies;
159
160 if (dst->is_local)
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, local_rcv, false);
171 }
172
173 if (local_rcv)
174 return br_pass_frame_up(skb);
175
176out:
177 return 0;
178drop:
179 kfree_skb(skb);
180 goto out;
181}
182EXPORT_SYMBOL_GPL(br_handle_frame_finish);
183
184static 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 && br_should_learn(p, skb, &vid))
191 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false);
192}
193
194/* note: already called with rcu_read_lock */
195static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
196{
197 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
198
199 __br_handle_local_finish(skb);
200
201 BR_INPUT_SKB_CB(skb)->brdev = p->br->dev;
202 br_pass_frame_up(skb);
203 return 0;
204}
205
206/*
207 * Return NULL if skb is handled
208 * note: already called with rcu_read_lock
209 */
210rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
211{
212 struct net_bridge_port *p;
213 struct sk_buff *skb = *pskb;
214 const unsigned char *dest = eth_hdr(skb)->h_dest;
215 br_should_route_hook_t *rhook;
216
217 if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
218 return RX_HANDLER_PASS;
219
220 if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
221 goto drop;
222
223 skb = skb_share_check(skb, GFP_ATOMIC);
224 if (!skb)
225 return RX_HANDLER_CONSUMED;
226
227 p = br_port_get_rcu(skb->dev);
228 if (p->flags & BR_VLAN_TUNNEL) {
229 if (br_handle_ingress_vlan_tunnel(skb, p,
230 nbp_vlan_group_rcu(p)))
231 goto drop;
232 }
233
234 if (unlikely(is_link_local_ether_addr(dest))) {
235 u16 fwd_mask = p->br->group_fwd_mask_required;
236
237 /*
238 * See IEEE 802.1D Table 7-10 Reserved addresses
239 *
240 * Assignment Value
241 * Bridge Group Address 01-80-C2-00-00-00
242 * (MAC Control) 802.3 01-80-C2-00-00-01
243 * (Link Aggregation) 802.3 01-80-C2-00-00-02
244 * 802.1X PAE address 01-80-C2-00-00-03
245 *
246 * 802.1AB LLDP 01-80-C2-00-00-0E
247 *
248 * Others reserved for future standardization
249 */
250 fwd_mask |= p->group_fwd_mask;
251 switch (dest[5]) {
252 case 0x00: /* Bridge Group Address */
253 /* If STP is turned off,
254 then must forward to keep loop detection */
255 if (p->br->stp_enabled == BR_NO_STP ||
256 fwd_mask & (1u << dest[5]))
257 goto forward;
258 *pskb = skb;
259 __br_handle_local_finish(skb);
260 return RX_HANDLER_PASS;
261
262 case 0x01: /* IEEE MAC (Pause) */
263 goto drop;
264
265 case 0x0E: /* 802.1AB LLDP */
266 fwd_mask |= p->br->group_fwd_mask;
267 if (fwd_mask & (1u << dest[5]))
268 goto forward;
269 *pskb = skb;
270 __br_handle_local_finish(skb);
271 return RX_HANDLER_PASS;
272
273 default:
274 /* Allow selective forwarding for most other protocols */
275 fwd_mask |= p->br->group_fwd_mask;
276 if (fwd_mask & (1u << dest[5]))
277 goto forward;
278 }
279
280 /* Deliver packet to local host only */
281 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, dev_net(skb->dev),
282 NULL, skb, skb->dev, NULL, br_handle_local_finish);
283 return RX_HANDLER_CONSUMED;
284 }
285
286forward:
287 switch (p->state) {
288 case BR_STATE_FORWARDING:
289 rhook = rcu_dereference(br_should_route_hook);
290 if (rhook) {
291 if ((*rhook)(skb)) {
292 *pskb = skb;
293 return RX_HANDLER_PASS;
294 }
295 dest = eth_hdr(skb)->h_dest;
296 }
297 /* fall through */
298 case BR_STATE_LEARNING:
299 if (ether_addr_equal(p->br->dev->dev_addr, dest))
300 skb->pkt_type = PACKET_HOST;
301
302 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING,
303 dev_net(skb->dev), NULL, skb, skb->dev, NULL,
304 br_handle_frame_finish);
305 break;
306 default:
307drop:
308 kfree_skb(skb);
309 }
310 return RX_HANDLER_CONSUMED;
311}