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 <linux/neighbour.h>
20#include <net/arp.h>
21#include <linux/export.h>
22#include <linux/rculist.h>
23#include "br_private.h"
24
25/* Hook for brouter */
26br_should_route_hook_t __rcu *br_should_route_hook __read_mostly;
27EXPORT_SYMBOL(br_should_route_hook);
28
29static int
30br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
31{
32 return netif_receive_skb(skb);
33}
34
35static int br_pass_frame_up(struct sk_buff *skb)
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);
41
42 u64_stats_update_begin(&brstats->syncp);
43 brstats->rx_packets++;
44 brstats->rx_bytes += skb->len;
45 u64_stats_update_end(&brstats->syncp);
46
47 vg = br_vlan_group_rcu(br);
48 /* Bridge is just like any other port. Make sure the
49 * packet is allowed except in promisc modue when someone
50 * may be running packet capture.
51 */
52 if (!(brdev->flags & IFF_PROMISC) &&
53 !br_allowed_egress(vg, skb)) {
54 kfree_skb(skb);
55 return NET_RX_DROP;
56 }
57
58 indev = skb->dev;
59 skb->dev = brdev;
60 skb = br_handle_vlan(br, vg, skb);
61 if (!skb)
62 return NET_RX_DROP;
63
64 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
65 dev_net(indev), NULL, skb, indev, NULL,
66 br_netif_receive_skb);
67}
68
69static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br,
70 u16 vid, struct net_bridge_port *p)
71{
72 struct net_device *dev = br->dev;
73 struct neighbour *n;
74 struct arphdr *parp;
75 u8 *arpptr, *sha;
76 __be32 sip, tip;
77
78 BR_INPUT_SKB_CB(skb)->proxyarp_replied = false;
79
80 if (dev->flags & IFF_NOARP)
81 return;
82
83 if (!pskb_may_pull(skb, arp_hdr_len(dev))) {
84 dev->stats.tx_dropped++;
85 return;
86 }
87 parp = arp_hdr(skb);
88
89 if (parp->ar_pro != htons(ETH_P_IP) ||
90 parp->ar_op != htons(ARPOP_REQUEST) ||
91 parp->ar_hln != dev->addr_len ||
92 parp->ar_pln != 4)
93 return;
94
95 arpptr = (u8 *)parp + sizeof(struct arphdr);
96 sha = arpptr;
97 arpptr += dev->addr_len; /* sha */
98 memcpy(&sip, arpptr, sizeof(sip));
99 arpptr += sizeof(sip);
100 arpptr += dev->addr_len; /* tha */
101 memcpy(&tip, arpptr, sizeof(tip));
102
103 if (ipv4_is_loopback(tip) ||
104 ipv4_is_multicast(tip))
105 return;
106
107 n = neigh_lookup(&arp_tbl, &tip, dev);
108 if (n) {
109 struct net_bridge_fdb_entry *f;
110
111 if (!(n->nud_state & NUD_VALID)) {
112 neigh_release(n);
113 return;
114 }
115
116 f = __br_fdb_get(br, n->ha, vid);
117 if (f && ((p->flags & BR_PROXYARP) ||
118 (f->dst && (f->dst->flags & BR_PROXYARP_WIFI)))) {
119 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip,
120 sha, n->ha, sha);
121 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
122 }
123
124 neigh_release(n);
125 }
126}
127
128/* note: already called with rcu_read_lock */
129int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
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;
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;
139
140 if (!p || p->state == BR_STATE_DISABLED)
141 goto drop;
142
143 if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(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 goto drop;
154
155 if (p->state == BR_STATE_LEARNING)
156 goto drop;
157
158 BR_INPUT_SKB_CB(skb)->brdev = br->dev;
159
160 /* The packet skb2 goes to the local host (NULL to skip). */
161 skb2 = NULL;
162
163 if (br->dev->flags & IFF_PROMISC)
164 skb2 = skb;
165
166 dst = NULL;
167
168 if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP))
169 br_do_proxy_arp(skb, br, vid, p);
170
171 if (is_broadcast_ether_addr(dest)) {
172 skb2 = skb;
173 unicast = false;
174 } 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 br_multicast_is_router(br))
180 skb2 = skb;
181 br_multicast_forward(mdst, skb, skb2);
182 skb = NULL;
183 if (!skb2)
184 goto out;
185 } else
186 skb2 = skb;
187
188 unicast = false;
189 br->dev->stats.multicast++;
190 } else if ((dst = __br_fdb_get(br, dest, vid)) &&
191 dst->is_local) {
192 skb2 = skb;
193 /* Do not forward the packet since it's local. */
194 skb = NULL;
195 }
196
197 if (skb) {
198 if (dst) {
199 dst->used = jiffies;
200 br_forward(dst->dst, skb, skb2);
201 } else
202 br_flood_forward(br, skb, skb2, unicast);
203 }
204
205 if (skb2)
206 return br_pass_frame_up(skb2);
207
208out:
209 return 0;
210drop:
211 kfree_skb(skb);
212 goto out;
213}
214EXPORT_SYMBOL_GPL(br_handle_frame_finish);
215
216/* note: already called with rcu_read_lock */
217static 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 /* check if vlan is allowed, to avoid spoofing */
223 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 BR_INPUT_SKB_CB(skb)->brdev = p->br->dev;
227 br_pass_frame_up(skb);
228 return 0;
229}
230
231/*
232 * Return NULL if skb is handled
233 * note: already called with rcu_read_lock
234 */
235rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
236{
237 struct net_bridge_port *p;
238 struct sk_buff *skb = *pskb;
239 const unsigned char *dest = eth_hdr(skb)->h_dest;
240 br_should_route_hook_t *rhook;
241
242 if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
243 return RX_HANDLER_PASS;
244
245 if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
246 goto drop;
247
248 skb = skb_share_check(skb, GFP_ATOMIC);
249 if (!skb)
250 return RX_HANDLER_CONSUMED;
251
252 p = br_port_get_rcu(skb->dev);
253
254 if (unlikely(is_link_local_ether_addr(dest))) {
255 u16 fwd_mask = p->br->group_fwd_mask_required;
256
257 /*
258 * See IEEE 802.1D Table 7-10 Reserved addresses
259 *
260 * Assignment Value
261 * Bridge Group Address 01-80-C2-00-00-00
262 * (MAC Control) 802.3 01-80-C2-00-00-01
263 * (Link Aggregation) 802.3 01-80-C2-00-00-02
264 * 802.1X PAE address 01-80-C2-00-00-03
265 *
266 * 802.1AB LLDP 01-80-C2-00-00-0E
267 *
268 * Others reserved for future standardization
269 */
270 switch (dest[5]) {
271 case 0x00: /* Bridge Group Address */
272 /* If STP is turned off,
273 then must forward to keep loop detection */
274 if (p->br->stp_enabled == BR_NO_STP ||
275 fwd_mask & (1u << dest[5]))
276 goto forward;
277 break;
278
279 case 0x01: /* IEEE MAC (Pause) */
280 goto drop;
281
282 default:
283 /* Allow selective forwarding for most other protocols */
284 fwd_mask |= p->br->group_fwd_mask;
285 if (fwd_mask & (1u << dest[5]))
286 goto forward;
287 }
288
289 /* Deliver packet to local host only */
290 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, dev_net(skb->dev),
291 NULL, skb, skb->dev, NULL, br_handle_local_finish);
292 return RX_HANDLER_CONSUMED;
293 }
294
295forward:
296 switch (p->state) {
297 case BR_STATE_FORWARDING:
298 rhook = rcu_dereference(br_should_route_hook);
299 if (rhook) {
300 if ((*rhook)(skb)) {
301 *pskb = skb;
302 return RX_HANDLER_PASS;
303 }
304 dest = eth_hdr(skb)->h_dest;
305 }
306 /* fall through */
307 case BR_STATE_LEARNING:
308 if (ether_addr_equal(p->br->dev->dev_addr, dest))
309 skb->pkt_type = PACKET_HOST;
310
311 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING,
312 dev_net(skb->dev), NULL, skb, skb->dev, NULL,
313 br_handle_frame_finish);
314 break;
315 default:
316drop:
317 kfree_skb(skb);
318 }
319 return RX_HANDLER_CONSUMED;
320}
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 */
24br_should_route_hook_t __rcu *br_should_route_hook __read_mostly;
25EXPORT_SYMBOL(br_should_route_hook);
26
27static 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 pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
32 struct net_port_vlans *pv;
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 /* Bridge is just like any other port. Make sure the
40 * packet is allowed except in promisc modue when someone
41 * may be running packet capture.
42 */
43 pv = br_get_vlan_info(br);
44 if (!(brdev->flags & IFF_PROMISC) &&
45 !br_allowed_egress(br, pv, skb)) {
46 kfree_skb(skb);
47 return NET_RX_DROP;
48 }
49
50 indev = skb->dev;
51 skb->dev = brdev;
52 skb = br_handle_vlan(br, pv, skb);
53 if (!skb)
54 return NET_RX_DROP;
55
56 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL,
57 netif_receive_skb);
58}
59
60/* note: already called with rcu_read_lock */
61int br_handle_frame_finish(struct sk_buff *skb)
62{
63 const unsigned char *dest = eth_hdr(skb)->h_dest;
64 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
65 struct net_bridge *br;
66 struct net_bridge_fdb_entry *dst;
67 struct net_bridge_mdb_entry *mdst;
68 struct sk_buff *skb2;
69 bool unicast = true;
70 u16 vid = 0;
71
72 if (!p || p->state == BR_STATE_DISABLED)
73 goto drop;
74
75 if (!br_allowed_ingress(p->br, nbp_get_vlan_info(p), skb, &vid))
76 goto out;
77
78 /* insert into forwarding database after filtering to avoid spoofing */
79 br = p->br;
80 if (p->flags & BR_LEARNING)
81 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false);
82
83 if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) &&
84 br_multicast_rcv(br, p, skb, vid))
85 goto drop;
86
87 if (p->state == BR_STATE_LEARNING)
88 goto drop;
89
90 BR_INPUT_SKB_CB(skb)->brdev = br->dev;
91
92 /* The packet skb2 goes to the local host (NULL to skip). */
93 skb2 = NULL;
94
95 if (br->dev->flags & IFF_PROMISC)
96 skb2 = skb;
97
98 dst = NULL;
99
100 if (is_broadcast_ether_addr(dest)) {
101 skb2 = skb;
102 unicast = false;
103 } else if (is_multicast_ether_addr(dest)) {
104 mdst = br_mdb_get(br, skb, vid);
105 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
106 br_multicast_querier_exists(br, eth_hdr(skb))) {
107 if ((mdst && mdst->mglist) ||
108 br_multicast_is_router(br))
109 skb2 = skb;
110 br_multicast_forward(mdst, skb, skb2);
111 skb = NULL;
112 if (!skb2)
113 goto out;
114 } else
115 skb2 = skb;
116
117 unicast = false;
118 br->dev->stats.multicast++;
119 } else if ((dst = __br_fdb_get(br, dest, vid)) &&
120 dst->is_local) {
121 skb2 = skb;
122 /* Do not forward the packet since it's local. */
123 skb = NULL;
124 }
125
126 if (skb) {
127 if (dst) {
128 dst->used = jiffies;
129 br_forward(dst->dst, skb, skb2);
130 } else
131 br_flood_forward(br, skb, skb2, unicast);
132 }
133
134 if (skb2)
135 return br_pass_frame_up(skb2);
136
137out:
138 return 0;
139drop:
140 kfree_skb(skb);
141 goto out;
142}
143
144/* note: already called with rcu_read_lock */
145static int br_handle_local_finish(struct sk_buff *skb)
146{
147 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
148 u16 vid = 0;
149
150 /* check if vlan is allowed, to avoid spoofing */
151 if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid))
152 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false);
153 return 0; /* process further */
154}
155
156/*
157 * Return NULL if skb is handled
158 * note: already called with rcu_read_lock
159 */
160rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
161{
162 struct net_bridge_port *p;
163 struct sk_buff *skb = *pskb;
164 const unsigned char *dest = eth_hdr(skb)->h_dest;
165 br_should_route_hook_t *rhook;
166
167 if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
168 return RX_HANDLER_PASS;
169
170 if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
171 goto drop;
172
173 skb = skb_share_check(skb, GFP_ATOMIC);
174 if (!skb)
175 return RX_HANDLER_CONSUMED;
176
177 p = br_port_get_rcu(skb->dev);
178
179 if (unlikely(is_link_local_ether_addr(dest))) {
180 /*
181 * See IEEE 802.1D Table 7-10 Reserved addresses
182 *
183 * Assignment Value
184 * Bridge Group Address 01-80-C2-00-00-00
185 * (MAC Control) 802.3 01-80-C2-00-00-01
186 * (Link Aggregation) 802.3 01-80-C2-00-00-02
187 * 802.1X PAE address 01-80-C2-00-00-03
188 *
189 * 802.1AB LLDP 01-80-C2-00-00-0E
190 *
191 * Others reserved for future standardization
192 */
193 switch (dest[5]) {
194 case 0x00: /* Bridge Group Address */
195 /* If STP is turned off,
196 then must forward to keep loop detection */
197 if (p->br->stp_enabled == BR_NO_STP)
198 goto forward;
199 break;
200
201 case 0x01: /* IEEE MAC (Pause) */
202 goto drop;
203
204 default:
205 /* Allow selective forwarding for most other protocols */
206 if (p->br->group_fwd_mask & (1u << dest[5]))
207 goto forward;
208 }
209
210 /* Deliver packet to local host only */
211 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
212 NULL, br_handle_local_finish)) {
213 return RX_HANDLER_CONSUMED; /* consumed by filter */
214 } else {
215 *pskb = skb;
216 return RX_HANDLER_PASS; /* continue processing */
217 }
218 }
219
220forward:
221 switch (p->state) {
222 case BR_STATE_FORWARDING:
223 rhook = rcu_dereference(br_should_route_hook);
224 if (rhook) {
225 if ((*rhook)(skb)) {
226 *pskb = skb;
227 return RX_HANDLER_PASS;
228 }
229 dest = eth_hdr(skb)->h_dest;
230 }
231 /* fall through */
232 case BR_STATE_LEARNING:
233 if (ether_addr_equal(p->br->dev->dev_addr, dest))
234 skb->pkt_type = PACKET_HOST;
235
236 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
237 br_handle_frame_finish);
238 break;
239 default:
240drop:
241 kfree_skb(skb);
242 }
243 return RX_HANDLER_CONSUMED;
244}