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Linux/net/bridge/br_input.c

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  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 
 26 static int
 27 br_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 
 33 static 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 */
 71 int 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 
174 out:
175         return 0;
176 drop:
177         kfree_skb(skb);
178         goto out;
179 }
180 EXPORT_SYMBOL_GPL(br_handle_frame_finish);
181 
182 static 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 */
196 static 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 
204 static 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         }
248 frame_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  */
261 static 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 
349 forward:
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:
358 drop:
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  */
371 static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb)
372 {
373         return RX_HANDLER_PASS;
374 }
375 
376 rx_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 }
383 

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