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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 */
26 br_should_route_hook_t __rcu *br_should_route_hook __read_mostly;
27 EXPORT_SYMBOL(br_should_route_hook);
28
29 static int
30 br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
31 {
32 return netif_receive_skb(skb);
33 }
34
35 static 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 /* update the multicast stats if the packet is IGMP/MLD */
64 br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb),
65 BR_MCAST_DIR_TX);
66
67 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
68 dev_net(indev), NULL, skb, indev, NULL,
69 br_netif_receive_skb);
70 }
71
72 static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br,
73 u16 vid, struct net_bridge_port *p)
74 {
75 struct net_device *dev = br->dev;
76 struct neighbour *n;
77 struct arphdr *parp;
78 u8 *arpptr, *sha;
79 __be32 sip, tip;
80
81 BR_INPUT_SKB_CB(skb)->proxyarp_replied = false;
82
83 if ((dev->flags & IFF_NOARP) ||
84 !pskb_may_pull(skb, arp_hdr_len(dev)))
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 */
129 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
130 {
131 bool local_rcv = false, mcast_hit = false, unicast = true;
132 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
133 const unsigned char *dest = eth_hdr(skb)->h_dest;
134 struct net_bridge_fdb_entry *dst = NULL;
135 struct net_bridge_mdb_entry *mdst;
136 struct net_bridge *br;
137 u16 vid = 0;
138
139 if (!p || p->state == BR_STATE_DISABLED)
140 goto drop;
141
142 if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(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 goto drop;
153
154 if (p->state == BR_STATE_LEARNING)
155 goto drop;
156
157 BR_INPUT_SKB_CB(skb)->brdev = br->dev;
158
159 local_rcv = !!(br->dev->flags & IFF_PROMISC);
160
161 if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP))
162 br_do_proxy_arp(skb, br, vid, p);
163
164 if (is_broadcast_ether_addr(dest)) {
165 local_rcv = true;
166 unicast = false;
167 } else if (is_multicast_ether_addr(dest)) {
168 mdst = br_mdb_get(br, skb, vid);
169 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
170 br_multicast_querier_exists(br, eth_hdr(skb))) {
171 if ((mdst && mdst->mglist) ||
172 br_multicast_is_router(br)) {
173 local_rcv = true;
174 br->dev->stats.multicast++;
175 }
176 mcast_hit = true;
177 } else {
178 local_rcv = true;
179 br->dev->stats.multicast++;
180 }
181 unicast = false;
182 } else if ((dst = __br_fdb_get(br, dest, vid)) && dst->is_local) {
183 /* Do not forward the packet since it's local. */
184 return br_pass_frame_up(skb);
185 }
186
187 if (dst) {
188 dst->used = jiffies;
189 br_forward(dst->dst, skb, local_rcv, false);
190 } else {
191 if (!mcast_hit)
192 br_flood(br, skb, unicast, local_rcv, false);
193 else
194 br_multicast_flood(mdst, skb, local_rcv, false);
195 }
196
197 if (local_rcv)
198 return br_pass_frame_up(skb);
199
200 out:
201 return 0;
202 drop:
203 kfree_skb(skb);
204 goto out;
205 }
206 EXPORT_SYMBOL_GPL(br_handle_frame_finish);
207
208 static void __br_handle_local_finish(struct sk_buff *skb)
209 {
210 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
211 u16 vid = 0;
212
213 /* check if vlan is allowed, to avoid spoofing */
214 if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid))
215 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false);
216 }
217
218 /* note: already called with rcu_read_lock */
219 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
220 {
221 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
222
223 __br_handle_local_finish(skb);
224
225 BR_INPUT_SKB_CB(skb)->brdev = p->br->dev;
226 br_pass_frame_up(skb);
227 return 0;
228 }
229
230 /*
231 * Return NULL if skb is handled
232 * note: already called with rcu_read_lock
233 */
234 rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
235 {
236 struct net_bridge_port *p;
237 struct sk_buff *skb = *pskb;
238 const unsigned char *dest = eth_hdr(skb)->h_dest;
239 br_should_route_hook_t *rhook;
240
241 if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
242 return RX_HANDLER_PASS;
243
244 if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
245 goto drop;
246
247 skb = skb_share_check(skb, GFP_ATOMIC);
248 if (!skb)
249 return RX_HANDLER_CONSUMED;
250
251 p = br_port_get_rcu(skb->dev);
252
253 if (unlikely(is_link_local_ether_addr(dest))) {
254 u16 fwd_mask = p->br->group_fwd_mask_required;
255
256 /*
257 * See IEEE 802.1D Table 7-10 Reserved addresses
258 *
259 * Assignment Value
260 * Bridge Group Address 01-80-C2-00-00-00
261 * (MAC Control) 802.3 01-80-C2-00-00-01
262 * (Link Aggregation) 802.3 01-80-C2-00-00-02
263 * 802.1X PAE address 01-80-C2-00-00-03
264 *
265 * 802.1AB LLDP 01-80-C2-00-00-0E
266 *
267 * Others reserved for future standardization
268 */
269 switch (dest[5]) {
270 case 0x00: /* Bridge Group Address */
271 /* If STP is turned off,
272 then must forward to keep loop detection */
273 if (p->br->stp_enabled == BR_NO_STP ||
274 fwd_mask & (1u << dest[5]))
275 goto forward;
276 *pskb = skb;
277 __br_handle_local_finish(skb);
278 return RX_HANDLER_PASS;
279
280 case 0x01: /* IEEE MAC (Pause) */
281 goto drop;
282
283 case 0x0E: /* 802.1AB LLDP */
284 fwd_mask |= p->br->group_fwd_mask;
285 if (fwd_mask & (1u << dest[5]))
286 goto forward;
287 *pskb = skb;
288 __br_handle_local_finish(skb);
289 return RX_HANDLER_PASS;
290
291 default:
292 /* Allow selective forwarding for most other protocols */
293 fwd_mask |= p->br->group_fwd_mask;
294 if (fwd_mask & (1u << dest[5]))
295 goto forward;
296 }
297
298 /* Deliver packet to local host only */
299 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, dev_net(skb->dev),
300 NULL, skb, skb->dev, NULL, br_handle_local_finish);
301 return RX_HANDLER_CONSUMED;
302 }
303
304 forward:
305 switch (p->state) {
306 case BR_STATE_FORWARDING:
307 rhook = rcu_dereference(br_should_route_hook);
308 if (rhook) {
309 if ((*rhook)(skb)) {
310 *pskb = skb;
311 return RX_HANDLER_PASS;
312 }
313 dest = eth_hdr(skb)->h_dest;
314 }
315 /* fall through */
316 case BR_STATE_LEARNING:
317 if (ether_addr_equal(p->br->dev->dev_addr, dest))
318 skb->pkt_type = PACKET_HOST;
319
320 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING,
321 dev_net(skb->dev), NULL, skb, skb->dev, NULL,
322 br_handle_frame_finish);
323 break;
324 default:
325 drop:
326 kfree_skb(skb);
327 }
328 return RX_HANDLER_CONSUMED;
329 }