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Linux/net/bridge/br_input.c

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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 #include "br_private_tunnel.h"
 25 
 26 /* Hook for brouter */
 27 br_should_route_hook_t __rcu *br_should_route_hook __read_mostly;
 28 EXPORT_SYMBOL(br_should_route_hook);
 29 
 30 static int
 31 br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
 32 {
 33         br_drop_fake_rtable(skb);
 34         return netif_receive_skb(skb);
 35 }
 36 
 37 static int br_pass_frame_up(struct sk_buff *skb)
 38 {
 39         struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
 40         struct net_bridge *br = netdev_priv(brdev);
 41         struct net_bridge_vlan_group *vg;
 42         struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
 43 
 44         u64_stats_update_begin(&brstats->syncp);
 45         brstats->rx_packets++;
 46         brstats->rx_bytes += skb->len;
 47         u64_stats_update_end(&brstats->syncp);
 48 
 49         vg = br_vlan_group_rcu(br);
 50         /* Bridge is just like any other port.  Make sure the
 51          * packet is allowed except in promisc modue when someone
 52          * may be running packet capture.
 53          */
 54         if (!(brdev->flags & IFF_PROMISC) &&
 55             !br_allowed_egress(vg, skb)) {
 56                 kfree_skb(skb);
 57                 return NET_RX_DROP;
 58         }
 59 
 60         indev = skb->dev;
 61         skb->dev = brdev;
 62         skb = br_handle_vlan(br, NULL, vg, skb);
 63         if (!skb)
 64                 return NET_RX_DROP;
 65         /* update the multicast stats if the packet is IGMP/MLD */
 66         br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb),
 67                            BR_MCAST_DIR_TX);
 68 
 69         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
 70                        dev_net(indev), NULL, skb, indev, NULL,
 71                        br_netif_receive_skb);
 72 }
 73 
 74 static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br,
 75                             u16 vid, struct net_bridge_port *p)
 76 {
 77         struct net_device *dev = br->dev;
 78         struct neighbour *n;
 79         struct arphdr *parp;
 80         u8 *arpptr, *sha;
 81         __be32 sip, tip;
 82 
 83         BR_INPUT_SKB_CB(skb)->proxyarp_replied = false;
 84 
 85         if ((dev->flags & IFF_NOARP) ||
 86             !pskb_may_pull(skb, arp_hdr_len(dev)))
 87                 return;
 88 
 89         parp = arp_hdr(skb);
 90 
 91         if (parp->ar_pro != htons(ETH_P_IP) ||
 92             parp->ar_op != htons(ARPOP_REQUEST) ||
 93             parp->ar_hln != dev->addr_len ||
 94             parp->ar_pln != 4)
 95                 return;
 96 
 97         arpptr = (u8 *)parp + sizeof(struct arphdr);
 98         sha = arpptr;
 99         arpptr += dev->addr_len;        /* sha */
100         memcpy(&sip, arpptr, sizeof(sip));
101         arpptr += sizeof(sip);
102         arpptr += dev->addr_len;        /* tha */
103         memcpy(&tip, arpptr, sizeof(tip));
104 
105         if (ipv4_is_loopback(tip) ||
106             ipv4_is_multicast(tip))
107                 return;
108 
109         n = neigh_lookup(&arp_tbl, &tip, dev);
110         if (n) {
111                 struct net_bridge_fdb_entry *f;
112 
113                 if (!(n->nud_state & NUD_VALID)) {
114                         neigh_release(n);
115                         return;
116                 }
117 
118                 f = br_fdb_find_rcu(br, n->ha, vid);
119                 if (f && ((p->flags & BR_PROXYARP) ||
120                           (f->dst && (f->dst->flags & BR_PROXYARP_WIFI)))) {
121                         arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip,
122                                  sha, n->ha, sha);
123                         BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
124                 }
125 
126                 neigh_release(n);
127         }
128 }
129 
130 /* note: already called with rcu_read_lock */
131 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
132 {
133         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
134         const unsigned char *dest = eth_hdr(skb)->h_dest;
135         enum br_pkt_type pkt_type = BR_PKT_UNICAST;
136         struct net_bridge_fdb_entry *dst = NULL;
137         struct net_bridge_mdb_entry *mdst;
138         bool local_rcv, mcast_hit = false;
139         struct net_bridge *br;
140         u16 vid = 0;
141 
142         if (!p || p->state == BR_STATE_DISABLED)
143                 goto drop;
144 
145         if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid))
146                 goto out;
147 
148         nbp_switchdev_frame_mark(p, skb);
149 
150         /* insert into forwarding database after filtering to avoid spoofing */
151         br = p->br;
152         if (p->flags & BR_LEARNING)
153                 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false);
154 
155         local_rcv = !!(br->dev->flags & IFF_PROMISC);
156         if (is_multicast_ether_addr(dest)) {
157                 /* by definition the broadcast is also a multicast address */
158                 if (is_broadcast_ether_addr(dest)) {
159                         pkt_type = BR_PKT_BROADCAST;
160                         local_rcv = true;
161                 } else {
162                         pkt_type = BR_PKT_MULTICAST;
163                         if (br_multicast_rcv(br, p, skb, vid))
164                                 goto drop;
165                 }
166         }
167 
168         if (p->state == BR_STATE_LEARNING)
169                 goto drop;
170 
171         BR_INPUT_SKB_CB(skb)->brdev = br->dev;
172 
173         if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP))
174                 br_do_proxy_arp(skb, br, vid, p);
175 
176         switch (pkt_type) {
177         case BR_PKT_MULTICAST:
178                 mdst = br_mdb_get(br, skb, vid);
179                 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
180                     br_multicast_querier_exists(br, eth_hdr(skb))) {
181                         if ((mdst && mdst->mglist) ||
182                             br_multicast_is_router(br)) {
183                                 local_rcv = true;
184                                 br->dev->stats.multicast++;
185                         }
186                         mcast_hit = true;
187                 } else {
188                         local_rcv = true;
189                         br->dev->stats.multicast++;
190                 }
191                 break;
192         case BR_PKT_UNICAST:
193                 dst = br_fdb_find_rcu(br, dest, vid);
194         default:
195                 break;
196         }
197 
198         if (dst) {
199                 unsigned long now = jiffies;
200 
201                 if (dst->is_local)
202                         return br_pass_frame_up(skb);
203 
204                 if (now != dst->used)
205                         dst->used = now;
206                 br_forward(dst->dst, skb, local_rcv, false);
207         } else {
208                 if (!mcast_hit)
209                         br_flood(br, skb, pkt_type, local_rcv, false);
210                 else
211                         br_multicast_flood(mdst, skb, local_rcv, false);
212         }
213 
214         if (local_rcv)
215                 return br_pass_frame_up(skb);
216 
217 out:
218         return 0;
219 drop:
220         kfree_skb(skb);
221         goto out;
222 }
223 EXPORT_SYMBOL_GPL(br_handle_frame_finish);
224 
225 static void __br_handle_local_finish(struct sk_buff *skb)
226 {
227         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
228         u16 vid = 0;
229 
230         /* check if vlan is allowed, to avoid spoofing */
231         if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid))
232                 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false);
233 }
234 
235 /* note: already called with rcu_read_lock */
236 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
237 {
238         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
239 
240         __br_handle_local_finish(skb);
241 
242         BR_INPUT_SKB_CB(skb)->brdev = p->br->dev;
243         br_pass_frame_up(skb);
244         return 0;
245 }
246 
247 /*
248  * Return NULL if skb is handled
249  * note: already called with rcu_read_lock
250  */
251 rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
252 {
253         struct net_bridge_port *p;
254         struct sk_buff *skb = *pskb;
255         const unsigned char *dest = eth_hdr(skb)->h_dest;
256         br_should_route_hook_t *rhook;
257 
258         if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
259                 return RX_HANDLER_PASS;
260 
261         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
262                 goto drop;
263 
264         skb = skb_share_check(skb, GFP_ATOMIC);
265         if (!skb)
266                 return RX_HANDLER_CONSUMED;
267 
268         p = br_port_get_rcu(skb->dev);
269         if (p->flags & BR_VLAN_TUNNEL) {
270                 if (br_handle_ingress_vlan_tunnel(skb, p,
271                                                   nbp_vlan_group_rcu(p)))
272                         goto drop;
273         }
274 
275         if (unlikely(is_link_local_ether_addr(dest))) {
276                 u16 fwd_mask = p->br->group_fwd_mask_required;
277 
278                 /*
279                  * See IEEE 802.1D Table 7-10 Reserved addresses
280                  *
281                  * Assignment                           Value
282                  * Bridge Group Address         01-80-C2-00-00-00
283                  * (MAC Control) 802.3          01-80-C2-00-00-01
284                  * (Link Aggregation) 802.3     01-80-C2-00-00-02
285                  * 802.1X PAE address           01-80-C2-00-00-03
286                  *
287                  * 802.1AB LLDP                 01-80-C2-00-00-0E
288                  *
289                  * Others reserved for future standardization
290                  */
291                 switch (dest[5]) {
292                 case 0x00:      /* Bridge Group Address */
293                         /* If STP is turned off,
294                            then must forward to keep loop detection */
295                         if (p->br->stp_enabled == BR_NO_STP ||
296                             fwd_mask & (1u << dest[5]))
297                                 goto forward;
298                         *pskb = skb;
299                         __br_handle_local_finish(skb);
300                         return RX_HANDLER_PASS;
301 
302                 case 0x01:      /* IEEE MAC (Pause) */
303                         goto drop;
304 
305                 case 0x0E:      /* 802.1AB LLDP */
306                         fwd_mask |= p->br->group_fwd_mask;
307                         if (fwd_mask & (1u << dest[5]))
308                                 goto forward;
309                         *pskb = skb;
310                         __br_handle_local_finish(skb);
311                         return RX_HANDLER_PASS;
312 
313                 default:
314                         /* Allow selective forwarding for most other protocols */
315                         fwd_mask |= p->br->group_fwd_mask;
316                         if (fwd_mask & (1u << dest[5]))
317                                 goto forward;
318                 }
319 
320                 /* Deliver packet to local host only */
321                 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, dev_net(skb->dev),
322                         NULL, skb, skb->dev, NULL, br_handle_local_finish);
323                 return RX_HANDLER_CONSUMED;
324         }
325 
326 forward:
327         switch (p->state) {
328         case BR_STATE_FORWARDING:
329                 rhook = rcu_dereference(br_should_route_hook);
330                 if (rhook) {
331                         if ((*rhook)(skb)) {
332                                 *pskb = skb;
333                                 return RX_HANDLER_PASS;
334                         }
335                         dest = eth_hdr(skb)->h_dest;
336                 }
337                 /* fall through */
338         case BR_STATE_LEARNING:
339                 if (ether_addr_equal(p->br->dev->dev_addr, dest))
340                         skb->pkt_type = PACKET_HOST;
341 
342                 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING,
343                         dev_net(skb->dev), NULL, skb, skb->dev, NULL,
344                         br_handle_frame_finish);
345                 break;
346         default:
347 drop:
348                 kfree_skb(skb);
349         }
350         return RX_HANDLER_CONSUMED;
351 }
352 

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