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
br_netif_receive_skb(struct net * net,struct sock * sk,struct sk_buff * skb)30 br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
31 {
32 br_drop_fake_rtable(skb);
33 return netif_receive_skb(skb);
34 }
35
br_pass_frame_up(struct sk_buff * skb)36 static int br_pass_frame_up(struct sk_buff *skb)
37 {
38 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
39 struct net_bridge *br = netdev_priv(brdev);
40 struct net_bridge_vlan_group *vg;
41 struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
42
43 u64_stats_update_begin(&brstats->syncp);
44 brstats->rx_packets++;
45 brstats->rx_bytes += skb->len;
46 u64_stats_update_end(&brstats->syncp);
47
48 vg = br_vlan_group_rcu(br);
49 /* Bridge is just like any other port. Make sure the
50 * packet is allowed except in promisc modue when someone
51 * may be running packet capture.
52 */
53 if (!(brdev->flags & IFF_PROMISC) &&
54 !br_allowed_egress(vg, skb)) {
55 kfree_skb(skb);
56 return NET_RX_DROP;
57 }
58
59 indev = skb->dev;
60 skb->dev = brdev;
61 skb = br_handle_vlan(br, vg, skb);
62 if (!skb)
63 return NET_RX_DROP;
64 /* update the multicast stats if the packet is IGMP/MLD */
65 br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb),
66 BR_MCAST_DIR_TX);
67
68 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
69 dev_net(indev), NULL, skb, indev, NULL,
70 br_netif_receive_skb);
71 }
72
br_do_proxy_arp(struct sk_buff * skb,struct net_bridge * br,u16 vid,struct net_bridge_port * p)73 static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br,
74 u16 vid, struct net_bridge_port *p)
75 {
76 struct net_device *dev = br->dev;
77 struct neighbour *n;
78 struct arphdr *parp;
79 u8 *arpptr, *sha;
80 __be32 sip, tip;
81
82 BR_INPUT_SKB_CB(skb)->proxyarp_replied = false;
83
84 if ((dev->flags & IFF_NOARP) ||
85 !pskb_may_pull(skb, arp_hdr_len(dev)))
86 return;
87
88 parp = arp_hdr(skb);
89
90 if (parp->ar_pro != htons(ETH_P_IP) ||
91 parp->ar_op != htons(ARPOP_REQUEST) ||
92 parp->ar_hln != dev->addr_len ||
93 parp->ar_pln != 4)
94 return;
95
96 arpptr = (u8 *)parp + sizeof(struct arphdr);
97 sha = arpptr;
98 arpptr += dev->addr_len; /* sha */
99 memcpy(&sip, arpptr, sizeof(sip));
100 arpptr += sizeof(sip);
101 arpptr += dev->addr_len; /* tha */
102 memcpy(&tip, arpptr, sizeof(tip));
103
104 if (ipv4_is_loopback(tip) ||
105 ipv4_is_multicast(tip))
106 return;
107
108 n = neigh_lookup(&arp_tbl, &tip, dev);
109 if (n) {
110 struct net_bridge_fdb_entry *f;
111
112 if (!(n->nud_state & NUD_VALID)) {
113 neigh_release(n);
114 return;
115 }
116
117 f = __br_fdb_get(br, n->ha, vid);
118 if (f && ((p->flags & BR_PROXYARP) ||
119 (f->dst && (f->dst->flags & BR_PROXYARP_WIFI)))) {
120 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip,
121 sha, n->ha, sha);
122 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
123 }
124
125 neigh_release(n);
126 }
127 }
128
129 /* note: already called with rcu_read_lock */
br_handle_frame_finish(struct net * net,struct sock * sk,struct sk_buff * skb)130 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
131 {
132 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
133 const unsigned char *dest = eth_hdr(skb)->h_dest;
134 enum br_pkt_type pkt_type = BR_PKT_UNICAST;
135 struct net_bridge_fdb_entry *dst = NULL;
136 struct net_bridge_mdb_entry *mdst;
137 bool local_rcv, mcast_hit = false;
138 struct net_bridge *br;
139 u16 vid = 0;
140
141 if (!p || p->state == BR_STATE_DISABLED)
142 goto drop;
143
144 if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid))
145 goto out;
146
147 nbp_switchdev_frame_mark(p, skb);
148
149 /* insert into forwarding database after filtering to avoid spoofing */
150 br = p->br;
151 if (p->flags & BR_LEARNING)
152 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false);
153
154 local_rcv = !!(br->dev->flags & IFF_PROMISC);
155 if (is_multicast_ether_addr(dest)) {
156 /* by definition the broadcast is also a multicast address */
157 if (is_broadcast_ether_addr(dest)) {
158 pkt_type = BR_PKT_BROADCAST;
159 local_rcv = true;
160 } else {
161 pkt_type = BR_PKT_MULTICAST;
162 if (br_multicast_rcv(br, p, skb, vid))
163 goto drop;
164 }
165 }
166
167 if (p->state == BR_STATE_LEARNING)
168 goto drop;
169
170 BR_INPUT_SKB_CB(skb)->brdev = br->dev;
171
172 if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP))
173 br_do_proxy_arp(skb, br, vid, p);
174
175 switch (pkt_type) {
176 case BR_PKT_MULTICAST:
177 mdst = br_mdb_get(br, skb, vid);
178 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
179 br_multicast_querier_exists(br, eth_hdr(skb))) {
180 if ((mdst && mdst->mglist) ||
181 br_multicast_is_router(br)) {
182 local_rcv = true;
183 br->dev->stats.multicast++;
184 }
185 mcast_hit = true;
186 } else {
187 local_rcv = true;
188 br->dev->stats.multicast++;
189 }
190 break;
191 case BR_PKT_UNICAST:
192 dst = __br_fdb_get(br, dest, vid);
193 default:
194 break;
195 }
196
197 if (dst) {
198 if (dst->is_local)
199 return br_pass_frame_up(skb);
200
201 dst->used = jiffies;
202 br_forward(dst->dst, skb, local_rcv, false);
203 } else {
204 if (!mcast_hit)
205 br_flood(br, skb, pkt_type, local_rcv, false);
206 else
207 br_multicast_flood(mdst, skb, local_rcv, false);
208 }
209
210 if (local_rcv)
211 return br_pass_frame_up(skb);
212
213 out:
214 return 0;
215 drop:
216 kfree_skb(skb);
217 goto out;
218 }
219 EXPORT_SYMBOL_GPL(br_handle_frame_finish);
220
__br_handle_local_finish(struct sk_buff * skb)221 static void __br_handle_local_finish(struct sk_buff *skb)
222 {
223 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
224 u16 vid = 0;
225
226 /* check if vlan is allowed, to avoid spoofing */
227 if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid))
228 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false);
229 }
230
231 /* note: already called with rcu_read_lock */
br_handle_local_finish(struct net * net,struct sock * sk,struct sk_buff * skb)232 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
233 {
234 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
235
236 __br_handle_local_finish(skb);
237
238 BR_INPUT_SKB_CB(skb)->brdev = p->br->dev;
239 br_pass_frame_up(skb);
240 return 0;
241 }
242
243 /*
244 * Return NULL if skb is handled
245 * note: already called with rcu_read_lock
246 */
br_handle_frame(struct sk_buff ** pskb)247 rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
248 {
249 struct net_bridge_port *p;
250 struct sk_buff *skb = *pskb;
251 const unsigned char *dest = eth_hdr(skb)->h_dest;
252 br_should_route_hook_t *rhook;
253
254 if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
255 return RX_HANDLER_PASS;
256
257 if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
258 goto drop;
259
260 skb = skb_share_check(skb, GFP_ATOMIC);
261 if (!skb)
262 return RX_HANDLER_CONSUMED;
263
264 p = br_port_get_rcu(skb->dev);
265
266 if (unlikely(is_link_local_ether_addr(dest))) {
267 u16 fwd_mask = p->br->group_fwd_mask_required;
268
269 /*
270 * See IEEE 802.1D Table 7-10 Reserved addresses
271 *
272 * Assignment Value
273 * Bridge Group Address 01-80-C2-00-00-00
274 * (MAC Control) 802.3 01-80-C2-00-00-01
275 * (Link Aggregation) 802.3 01-80-C2-00-00-02
276 * 802.1X PAE address 01-80-C2-00-00-03
277 *
278 * 802.1AB LLDP 01-80-C2-00-00-0E
279 *
280 * Others reserved for future standardization
281 */
282 switch (dest[5]) {
283 case 0x00: /* Bridge Group Address */
284 /* If STP is turned off,
285 then must forward to keep loop detection */
286 if (p->br->stp_enabled == BR_NO_STP ||
287 fwd_mask & (1u << dest[5]))
288 goto forward;
289 *pskb = skb;
290 __br_handle_local_finish(skb);
291 return RX_HANDLER_PASS;
292
293 case 0x01: /* IEEE MAC (Pause) */
294 goto drop;
295
296 case 0x0E: /* 802.1AB LLDP */
297 fwd_mask |= p->br->group_fwd_mask;
298 if (fwd_mask & (1u << dest[5]))
299 goto forward;
300 *pskb = skb;
301 __br_handle_local_finish(skb);
302 return RX_HANDLER_PASS;
303
304 default:
305 /* Allow selective forwarding for most other protocols */
306 fwd_mask |= p->br->group_fwd_mask;
307 if (fwd_mask & (1u << dest[5]))
308 goto forward;
309 }
310
311 /* Deliver packet to local host only */
312 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, dev_net(skb->dev),
313 NULL, skb, skb->dev, NULL, br_handle_local_finish);
314 return RX_HANDLER_CONSUMED;
315 }
316
317 forward:
318 switch (p->state) {
319 case BR_STATE_FORWARDING:
320 rhook = rcu_dereference(br_should_route_hook);
321 if (rhook) {
322 if ((*rhook)(skb)) {
323 *pskb = skb;
324 return RX_HANDLER_PASS;
325 }
326 dest = eth_hdr(skb)->h_dest;
327 }
328 /* fall through */
329 case BR_STATE_LEARNING:
330 if (ether_addr_equal(p->br->dev->dev_addr, dest))
331 skb->pkt_type = PACKET_HOST;
332
333 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING,
334 dev_net(skb->dev), NULL, skb, skb->dev, NULL,
335 br_handle_frame_finish);
336 break;
337 default:
338 drop:
339 kfree_skb(skb);
340 }
341 return RX_HANDLER_CONSUMED;
342 }
343