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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 "br_private.h"
21
22/* Bridge group multicast address 802.1d (pg 51). */
23const u8 br_group_address[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 };
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 br_pass_frame_up(struct sk_buff *skb)
30{
31 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
32 struct net_bridge *br = netdev_priv(brdev);
33 struct br_cpu_netstats *brstats = this_cpu_ptr(br->stats);
34
35 u64_stats_update_begin(&brstats->syncp);
36 brstats->rx_packets++;
37 brstats->rx_bytes += skb->len;
38 u64_stats_update_end(&brstats->syncp);
39
40 indev = skb->dev;
41 skb->dev = brdev;
42
43 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL,
44 netif_receive_skb);
45}
46
47/* note: already called with rcu_read_lock */
48int br_handle_frame_finish(struct sk_buff *skb)
49{
50 const unsigned char *dest = eth_hdr(skb)->h_dest;
51 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
52 struct net_bridge *br;
53 struct net_bridge_fdb_entry *dst;
54 struct net_bridge_mdb_entry *mdst;
55 struct sk_buff *skb2;
56
57 if (!p || p->state == BR_STATE_DISABLED)
58 goto drop;
59
60 /* insert into forwarding database after filtering to avoid spoofing */
61 br = p->br;
62 br_fdb_update(br, p, eth_hdr(skb)->h_source);
63
64 if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) &&
65 br_multicast_rcv(br, p, skb))
66 goto drop;
67
68 if (p->state == BR_STATE_LEARNING)
69 goto drop;
70
71 BR_INPUT_SKB_CB(skb)->brdev = br->dev;
72
73 /* The packet skb2 goes to the local host (NULL to skip). */
74 skb2 = NULL;
75
76 if (br->dev->flags & IFF_PROMISC)
77 skb2 = skb;
78
79 dst = NULL;
80
81 if (is_broadcast_ether_addr(dest))
82 skb2 = skb;
83 else if (is_multicast_ether_addr(dest)) {
84 mdst = br_mdb_get(br, skb);
85 if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) {
86 if ((mdst && mdst->mglist) ||
87 br_multicast_is_router(br))
88 skb2 = skb;
89 br_multicast_forward(mdst, skb, skb2);
90 skb = NULL;
91 if (!skb2)
92 goto out;
93 } else
94 skb2 = skb;
95
96 br->dev->stats.multicast++;
97 } else if ((dst = __br_fdb_get(br, dest)) && dst->is_local) {
98 skb2 = skb;
99 /* Do not forward the packet since it's local. */
100 skb = NULL;
101 }
102
103 if (skb) {
104 if (dst) {
105 dst->used = jiffies;
106 br_forward(dst->dst, skb, skb2);
107 } else
108 br_flood_forward(br, skb, skb2);
109 }
110
111 if (skb2)
112 return br_pass_frame_up(skb2);
113
114out:
115 return 0;
116drop:
117 kfree_skb(skb);
118 goto out;
119}
120
121/* note: already called with rcu_read_lock */
122static int br_handle_local_finish(struct sk_buff *skb)
123{
124 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
125
126 br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
127 return 0; /* process further */
128}
129
130/* Does address match the link local multicast address.
131 * 01:80:c2:00:00:0X
132 */
133static inline int is_link_local(const unsigned char *dest)
134{
135 __be16 *a = (__be16 *)dest;
136 static const __be16 *b = (const __be16 *)br_group_address;
137 static const __be16 m = cpu_to_be16(0xfff0);
138
139 return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0;
140}
141
142/*
143 * Return NULL if skb is handled
144 * note: already called with rcu_read_lock
145 */
146rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
147{
148 struct net_bridge_port *p;
149 struct sk_buff *skb = *pskb;
150 const unsigned char *dest = eth_hdr(skb)->h_dest;
151 br_should_route_hook_t *rhook;
152
153 if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
154 return RX_HANDLER_PASS;
155
156 if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
157 goto drop;
158
159 skb = skb_share_check(skb, GFP_ATOMIC);
160 if (!skb)
161 return RX_HANDLER_CONSUMED;
162
163 p = br_port_get_rcu(skb->dev);
164
165 if (unlikely(is_link_local(dest))) {
166 /*
167 * See IEEE 802.1D Table 7-10 Reserved addresses
168 *
169 * Assignment Value
170 * Bridge Group Address 01-80-C2-00-00-00
171 * (MAC Control) 802.3 01-80-C2-00-00-01
172 * (Link Aggregation) 802.3 01-80-C2-00-00-02
173 * 802.1X PAE address 01-80-C2-00-00-03
174 *
175 * 802.1AB LLDP 01-80-C2-00-00-0E
176 *
177 * Others reserved for future standardization
178 */
179 switch (dest[5]) {
180 case 0x00: /* Bridge Group Address */
181 /* If STP is turned off,
182 then must forward to keep loop detection */
183 if (p->br->stp_enabled == BR_NO_STP)
184 goto forward;
185 break;
186
187 case 0x01: /* IEEE MAC (Pause) */
188 goto drop;
189
190 default:
191 /* Allow selective forwarding for most other protocols */
192 if (p->br->group_fwd_mask & (1u << dest[5]))
193 goto forward;
194 }
195
196 /* Deliver packet to local host only */
197 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
198 NULL, br_handle_local_finish)) {
199 return RX_HANDLER_CONSUMED; /* consumed by filter */
200 } else {
201 *pskb = skb;
202 return RX_HANDLER_PASS; /* continue processing */
203 }
204 }
205
206forward:
207 switch (p->state) {
208 case BR_STATE_FORWARDING:
209 rhook = rcu_dereference(br_should_route_hook);
210 if (rhook) {
211 if ((*rhook)(skb)) {
212 *pskb = skb;
213 return RX_HANDLER_PASS;
214 }
215 dest = eth_hdr(skb)->h_dest;
216 }
217 /* fall through */
218 case BR_STATE_LEARNING:
219 if (ether_addr_equal(p->br->dev->dev_addr, dest))
220 skb->pkt_type = PACKET_HOST;
221
222 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
223 br_handle_frame_finish);
224 break;
225 default:
226drop:
227 kfree_skb(skb);
228 }
229 return RX_HANDLER_CONSUMED;
230}