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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 "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// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Handle incoming frames
4 * Linux ethernet bridge
5 *
6 * Authors:
7 * Lennert Buytenhek <buytenh@gnu.org>
8 */
9
10#include <linux/slab.h>
11#include <linux/kernel.h>
12#include <linux/netdevice.h>
13#include <linux/etherdevice.h>
14#include <linux/netfilter_bridge.h>
15#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
16#include <net/netfilter/nf_queue.h>
17#endif
18#include <linux/neighbour.h>
19#include <net/arp.h>
20#include <net/dsa.h>
21#include <linux/export.h>
22#include <linux/rculist.h>
23#include "br_private.h"
24#include "br_private_tunnel.h"
25
26static int
27br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
28{
29 br_drop_fake_rtable(skb);
30 return netif_receive_skb(skb);
31}
32
33static int br_pass_frame_up(struct sk_buff *skb)
34{
35 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
36 struct net_bridge *br = netdev_priv(brdev);
37 struct net_bridge_vlan_group *vg;
38 struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
39
40 u64_stats_update_begin(&brstats->syncp);
41 brstats->rx_packets++;
42 brstats->rx_bytes += skb->len;
43 u64_stats_update_end(&brstats->syncp);
44
45 vg = br_vlan_group_rcu(br);
46 /* Bridge is just like any other port. Make sure the
47 * packet is allowed except in promisc modue when someone
48 * may be running packet capture.
49 */
50 if (!(brdev->flags & IFF_PROMISC) &&
51 !br_allowed_egress(vg, skb)) {
52 kfree_skb(skb);
53 return NET_RX_DROP;
54 }
55
56 indev = skb->dev;
57 skb->dev = brdev;
58 skb = br_handle_vlan(br, NULL, vg, skb);
59 if (!skb)
60 return NET_RX_DROP;
61 /* update the multicast stats if the packet is IGMP/MLD */
62 br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb),
63 BR_MCAST_DIR_TX);
64
65 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
66 dev_net(indev), NULL, skb, indev, NULL,
67 br_netif_receive_skb);
68}
69
70/* note: already called with rcu_read_lock */
71int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
72{
73 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
74 enum br_pkt_type pkt_type = BR_PKT_UNICAST;
75 struct net_bridge_fdb_entry *dst = NULL;
76 struct net_bridge_mdb_entry *mdst;
77 bool local_rcv, mcast_hit = false;
78 struct net_bridge *br;
79 u16 vid = 0;
80 u8 state;
81
82 if (!p || p->state == BR_STATE_DISABLED)
83 goto drop;
84
85 state = p->state;
86 if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid,
87 &state))
88 goto out;
89
90 nbp_switchdev_frame_mark(p, skb);
91
92 /* insert into forwarding database after filtering to avoid spoofing */
93 br = p->br;
94 if (p->flags & BR_LEARNING)
95 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, 0);
96
97 local_rcv = !!(br->dev->flags & IFF_PROMISC);
98 if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) {
99 /* by definition the broadcast is also a multicast address */
100 if (is_broadcast_ether_addr(eth_hdr(skb)->h_dest)) {
101 pkt_type = BR_PKT_BROADCAST;
102 local_rcv = true;
103 } else {
104 pkt_type = BR_PKT_MULTICAST;
105 if (br_multicast_rcv(br, p, skb, vid))
106 goto drop;
107 }
108 }
109
110 if (state == BR_STATE_LEARNING)
111 goto drop;
112
113 BR_INPUT_SKB_CB(skb)->brdev = br->dev;
114 BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED);
115
116 if (IS_ENABLED(CONFIG_INET) &&
117 (skb->protocol == htons(ETH_P_ARP) ||
118 skb->protocol == htons(ETH_P_RARP))) {
119 br_do_proxy_suppress_arp(skb, br, vid, p);
120 } else if (IS_ENABLED(CONFIG_IPV6) &&
121 skb->protocol == htons(ETH_P_IPV6) &&
122 br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) &&
123 pskb_may_pull(skb, sizeof(struct ipv6hdr) +
124 sizeof(struct nd_msg)) &&
125 ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) {
126 struct nd_msg *msg, _msg;
127
128 msg = br_is_nd_neigh_msg(skb, &_msg);
129 if (msg)
130 br_do_suppress_nd(skb, br, vid, p, msg);
131 }
132
133 switch (pkt_type) {
134 case BR_PKT_MULTICAST:
135 mdst = br_mdb_get(br, skb, vid);
136 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
137 br_multicast_querier_exists(br, eth_hdr(skb))) {
138 if ((mdst && mdst->host_joined) ||
139 br_multicast_is_router(br)) {
140 local_rcv = true;
141 br->dev->stats.multicast++;
142 }
143 mcast_hit = true;
144 } else {
145 local_rcv = true;
146 br->dev->stats.multicast++;
147 }
148 break;
149 case BR_PKT_UNICAST:
150 dst = br_fdb_find_rcu(br, eth_hdr(skb)->h_dest, vid);
151 default:
152 break;
153 }
154
155 if (dst) {
156 unsigned long now = jiffies;
157
158 if (test_bit(BR_FDB_LOCAL, &dst->flags))
159 return br_pass_frame_up(skb);
160
161 if (now != dst->used)
162 dst->used = now;
163 br_forward(dst->dst, skb, local_rcv, false);
164 } else {
165 if (!mcast_hit)
166 br_flood(br, skb, pkt_type, local_rcv, false);
167 else
168 br_multicast_flood(mdst, skb, local_rcv, false);
169 }
170
171 if (local_rcv)
172 return br_pass_frame_up(skb);
173
174out:
175 return 0;
176drop:
177 kfree_skb(skb);
178 goto out;
179}
180EXPORT_SYMBOL_GPL(br_handle_frame_finish);
181
182static void __br_handle_local_finish(struct sk_buff *skb)
183{
184 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
185 u16 vid = 0;
186
187 /* check if vlan is allowed, to avoid spoofing */
188 if ((p->flags & BR_LEARNING) &&
189 nbp_state_should_learn(p) &&
190 !br_opt_get(p->br, BROPT_NO_LL_LEARN) &&
191 br_should_learn(p, skb, &vid))
192 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, 0);
193}
194
195/* note: already called with rcu_read_lock */
196static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
197{
198 __br_handle_local_finish(skb);
199
200 /* return 1 to signal the okfn() was called so it's ok to use the skb */
201 return 1;
202}
203
204static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb)
205{
206#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
207 struct nf_hook_entries *e = NULL;
208 struct nf_hook_state state;
209 unsigned int verdict, i;
210 struct net *net;
211 int ret;
212
213 net = dev_net(skb->dev);
214#ifdef HAVE_JUMP_LABEL
215 if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING]))
216 goto frame_finish;
217#endif
218
219 e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]);
220 if (!e)
221 goto frame_finish;
222
223 nf_hook_state_init(&state, NF_BR_PRE_ROUTING,
224 NFPROTO_BRIDGE, skb->dev, NULL, NULL,
225 net, br_handle_frame_finish);
226
227 for (i = 0; i < e->num_hook_entries; i++) {
228 verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state);
229 switch (verdict & NF_VERDICT_MASK) {
230 case NF_ACCEPT:
231 if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) {
232 *pskb = skb;
233 return RX_HANDLER_PASS;
234 }
235 break;
236 case NF_DROP:
237 kfree_skb(skb);
238 return RX_HANDLER_CONSUMED;
239 case NF_QUEUE:
240 ret = nf_queue(skb, &state, i, verdict);
241 if (ret == 1)
242 continue;
243 return RX_HANDLER_CONSUMED;
244 default: /* STOLEN */
245 return RX_HANDLER_CONSUMED;
246 }
247 }
248frame_finish:
249 net = dev_net(skb->dev);
250 br_handle_frame_finish(net, NULL, skb);
251#else
252 br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
253#endif
254 return RX_HANDLER_CONSUMED;
255}
256
257/*
258 * Return NULL if skb is handled
259 * note: already called with rcu_read_lock
260 */
261static rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
262{
263 struct net_bridge_port *p;
264 struct sk_buff *skb = *pskb;
265 const unsigned char *dest = eth_hdr(skb)->h_dest;
266
267 if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
268 return RX_HANDLER_PASS;
269
270 if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
271 goto drop;
272
273 skb = skb_share_check(skb, GFP_ATOMIC);
274 if (!skb)
275 return RX_HANDLER_CONSUMED;
276
277 memset(skb->cb, 0, sizeof(struct br_input_skb_cb));
278
279 p = br_port_get_rcu(skb->dev);
280 if (p->flags & BR_VLAN_TUNNEL) {
281 if (br_handle_ingress_vlan_tunnel(skb, p,
282 nbp_vlan_group_rcu(p)))
283 goto drop;
284 }
285
286 if (unlikely(is_link_local_ether_addr(dest))) {
287 u16 fwd_mask = p->br->group_fwd_mask_required;
288
289 /*
290 * See IEEE 802.1D Table 7-10 Reserved addresses
291 *
292 * Assignment Value
293 * Bridge Group Address 01-80-C2-00-00-00
294 * (MAC Control) 802.3 01-80-C2-00-00-01
295 * (Link Aggregation) 802.3 01-80-C2-00-00-02
296 * 802.1X PAE address 01-80-C2-00-00-03
297 *
298 * 802.1AB LLDP 01-80-C2-00-00-0E
299 *
300 * Others reserved for future standardization
301 */
302 fwd_mask |= p->group_fwd_mask;
303 switch (dest[5]) {
304 case 0x00: /* Bridge Group Address */
305 /* If STP is turned off,
306 then must forward to keep loop detection */
307 if (p->br->stp_enabled == BR_NO_STP ||
308 fwd_mask & (1u << dest[5]))
309 goto forward;
310 *pskb = skb;
311 __br_handle_local_finish(skb);
312 return RX_HANDLER_PASS;
313
314 case 0x01: /* IEEE MAC (Pause) */
315 goto drop;
316
317 case 0x0E: /* 802.1AB LLDP */
318 fwd_mask |= p->br->group_fwd_mask;
319 if (fwd_mask & (1u << dest[5]))
320 goto forward;
321 *pskb = skb;
322 __br_handle_local_finish(skb);
323 return RX_HANDLER_PASS;
324
325 default:
326 /* Allow selective forwarding for most other protocols */
327 fwd_mask |= p->br->group_fwd_mask;
328 if (fwd_mask & (1u << dest[5]))
329 goto forward;
330 }
331
332 /* The else clause should be hit when nf_hook():
333 * - returns < 0 (drop/error)
334 * - returns = 0 (stolen/nf_queue)
335 * Thus return 1 from the okfn() to signal the skb is ok to pass
336 */
337 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
338 dev_net(skb->dev), NULL, skb, skb->dev, NULL,
339 br_handle_local_finish) == 1) {
340 return RX_HANDLER_PASS;
341 } else {
342 return RX_HANDLER_CONSUMED;
343 }
344 }
345
346 if (unlikely(br_mrp_process(p, skb)))
347 return RX_HANDLER_PASS;
348
349forward:
350 switch (p->state) {
351 case BR_STATE_FORWARDING:
352 case BR_STATE_LEARNING:
353 if (ether_addr_equal(p->br->dev->dev_addr, dest))
354 skb->pkt_type = PACKET_HOST;
355
356 return nf_hook_bridge_pre(skb, pskb);
357 default:
358drop:
359 kfree_skb(skb);
360 }
361 return RX_HANDLER_CONSUMED;
362}
363
364/* This function has no purpose other than to appease the br_port_get_rcu/rtnl
365 * helpers which identify bridged ports according to the rx_handler installed
366 * on them (so there _needs_ to be a bridge rx_handler even if we don't need it
367 * to do anything useful). This bridge won't support traffic to/from the stack,
368 * but only hardware bridging. So return RX_HANDLER_PASS so we don't steal
369 * frames from the ETH_P_XDSA packet_type handler.
370 */
371static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb)
372{
373 return RX_HANDLER_PASS;
374}
375
376rx_handler_func_t *br_get_rx_handler(const struct net_device *dev)
377{
378 if (netdev_uses_dsa(dev))
379 return br_handle_frame_dummy;
380
381 return br_handle_frame;
382}