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

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