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Linux/net/ipv6/ip6_input.c

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  1 /*
  2  *      IPv6 input
  3  *      Linux INET6 implementation
  4  *
  5  *      Authors:
  6  *      Pedro Roque             <roque@di.fc.ul.pt>
  7  *      Ian P. Morris           <I.P.Morris@soton.ac.uk>
  8  *
  9  *      Based in linux/net/ipv4/ip_input.c
 10  *
 11  *      This program is free software; you can redistribute it and/or
 12  *      modify it under the terms of the GNU General Public License
 13  *      as published by the Free Software Foundation; either version
 14  *      2 of the License, or (at your option) any later version.
 15  */
 16 /* Changes
 17  *
 18  *      Mitsuru KANDA @USAGI and
 19  *      YOSHIFUJI Hideaki @USAGI: Remove ipv6_parse_exthdrs().
 20  */
 21 
 22 #include <linux/errno.h>
 23 #include <linux/types.h>
 24 #include <linux/socket.h>
 25 #include <linux/sockios.h>
 26 #include <linux/net.h>
 27 #include <linux/netdevice.h>
 28 #include <linux/in6.h>
 29 #include <linux/icmpv6.h>
 30 #include <linux/mroute6.h>
 31 
 32 #include <linux/netfilter.h>
 33 #include <linux/netfilter_ipv6.h>
 34 
 35 #include <net/sock.h>
 36 #include <net/snmp.h>
 37 
 38 #include <net/ipv6.h>
 39 #include <net/protocol.h>
 40 #include <net/transp_v6.h>
 41 #include <net/rawv6.h>
 42 #include <net/ndisc.h>
 43 #include <net/ip6_route.h>
 44 #include <net/addrconf.h>
 45 #include <net/xfrm.h>
 46 
 47 
 48 
 49 inline int ip6_rcv_finish( struct sk_buff *skb)
 50 {
 51         if (skb_dst(skb) == NULL)
 52                 ip6_route_input(skb);
 53 
 54         return dst_input(skb);
 55 }
 56 
 57 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
 58 {
 59         struct ipv6hdr *hdr;
 60         u32             pkt_len;
 61         struct inet6_dev *idev;
 62         struct net *net = dev_net(skb->dev);
 63 
 64         if (skb->pkt_type == PACKET_OTHERHOST) {
 65                 kfree_skb(skb);
 66                 return NET_RX_DROP;
 67         }
 68 
 69         rcu_read_lock();
 70 
 71         idev = __in6_dev_get(skb->dev);
 72 
 73         IP6_UPD_PO_STATS_BH(net, idev, IPSTATS_MIB_IN, skb->len);
 74 
 75         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
 76             !idev || unlikely(idev->cnf.disable_ipv6)) {
 77                 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
 78                 goto drop;
 79         }
 80 
 81         memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
 82 
 83         /*
 84          * Store incoming device index. When the packet will
 85          * be queued, we cannot refer to skb->dev anymore.
 86          *
 87          * BTW, when we send a packet for our own local address on a
 88          * non-loopback interface (e.g. ethX), it is being delivered
 89          * via the loopback interface (lo) here; skb->dev = loopback_dev.
 90          * It, however, should be considered as if it is being
 91          * arrived via the sending interface (ethX), because of the
 92          * nature of scoping architecture. --yoshfuji
 93          */
 94         IP6CB(skb)->iif = skb_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;
 95 
 96         if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
 97                 goto err;
 98 
 99         hdr = ipv6_hdr(skb);
100 
101         if (hdr->version != 6)
102                 goto err;
103 
104         /*
105          * RFC4291 2.5.3
106          * A packet received on an interface with a destination address
107          * of loopback must be dropped.
108          */
109         if (!(dev->flags & IFF_LOOPBACK) &&
110             ipv6_addr_loopback(&hdr->daddr))
111                 goto err;
112 
113         skb->transport_header = skb->network_header + sizeof(*hdr);
114         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
115 
116         pkt_len = ntohs(hdr->payload_len);
117 
118         /* pkt_len may be zero if Jumbo payload option is present */
119         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
120                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
121                         IP6_INC_STATS_BH(net,
122                                          idev, IPSTATS_MIB_INTRUNCATEDPKTS);
123                         goto drop;
124                 }
125                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
126                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
127                         goto drop;
128                 }
129                 hdr = ipv6_hdr(skb);
130         }
131 
132         if (hdr->nexthdr == NEXTHDR_HOP) {
133                 if (ipv6_parse_hopopts(skb) < 0) {
134                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
135                         rcu_read_unlock();
136                         return NET_RX_DROP;
137                 }
138         }
139 
140         rcu_read_unlock();
141 
142         /* Must drop socket now because of tproxy. */
143         skb_orphan(skb);
144 
145         return NF_HOOK(PF_INET6, NF_INET_PRE_ROUTING, skb, dev, NULL,
146                        ip6_rcv_finish);
147 err:
148         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
149 drop:
150         rcu_read_unlock();
151         kfree_skb(skb);
152         return NET_RX_DROP;
153 }
154 
155 /*
156  *      Deliver the packet to the host
157  */
158 
159 
160 static int ip6_input_finish(struct sk_buff *skb)
161 {
162         const struct inet6_protocol *ipprot;
163         unsigned int nhoff;
164         int nexthdr, raw;
165         u8 hash;
166         struct inet6_dev *idev;
167         struct net *net = dev_net(skb_dst(skb)->dev);
168 
169         /*
170          *      Parse extension headers
171          */
172 
173         rcu_read_lock();
174 resubmit:
175         idev = ip6_dst_idev(skb_dst(skb));
176         if (!pskb_pull(skb, skb_transport_offset(skb)))
177                 goto discard;
178         nhoff = IP6CB(skb)->nhoff;
179         nexthdr = skb_network_header(skb)[nhoff];
180 
181         raw = raw6_local_deliver(skb, nexthdr);
182 
183         hash = nexthdr & (MAX_INET_PROTOS - 1);
184         if ((ipprot = rcu_dereference(inet6_protos[hash])) != NULL) {
185                 int ret;
186 
187                 if (ipprot->flags & INET6_PROTO_FINAL) {
188                         struct ipv6hdr *hdr;
189 
190                         /* Free reference early: we don't need it any more,
191                            and it may hold ip_conntrack module loaded
192                            indefinitely. */
193                         nf_reset(skb);
194 
195                         skb_postpull_rcsum(skb, skb_network_header(skb),
196                                            skb_network_header_len(skb));
197                         hdr = ipv6_hdr(skb);
198                         if (ipv6_addr_is_multicast(&hdr->daddr) &&
199                             !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
200                             &hdr->saddr) &&
201                             !ipv6_is_mld(skb, nexthdr))
202                                 goto discard;
203                 }
204                 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
205                     !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
206                         goto discard;
207 
208                 ret = ipprot->handler(skb);
209                 if (ret > 0)
210                         goto resubmit;
211                 else if (ret == 0)
212                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
213         } else {
214                 if (!raw) {
215                         if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
216                                 IP6_INC_STATS_BH(net, idev,
217                                                  IPSTATS_MIB_INUNKNOWNPROTOS);
218                                 icmpv6_send(skb, ICMPV6_PARAMPROB,
219                                             ICMPV6_UNK_NEXTHDR, nhoff,
220                                             skb->dev);
221                         }
222                 } else
223                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
224                 kfree_skb(skb);
225         }
226         rcu_read_unlock();
227         return 0;
228 
229 discard:
230         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
231         rcu_read_unlock();
232         kfree_skb(skb);
233         return 0;
234 }
235 
236 
237 int ip6_input(struct sk_buff *skb)
238 {
239         return NF_HOOK(PF_INET6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
240                        ip6_input_finish);
241 }
242 
243 int ip6_mc_input(struct sk_buff *skb)
244 {
245         struct ipv6hdr *hdr;
246         int deliver;
247 
248         IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev),
249                          ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
250                          skb->len);
251 
252         hdr = ipv6_hdr(skb);
253         deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
254 
255 #ifdef CONFIG_IPV6_MROUTE
256         /*
257          *      IPv6 multicast router mode is now supported ;)
258          */
259         if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
260             !(ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) &&
261             likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
262                 /*
263                  * Okay, we try to forward - split and duplicate
264                  * packets.
265                  */
266                 struct sk_buff *skb2;
267                 struct inet6_skb_parm *opt = IP6CB(skb);
268 
269                 /* Check for MLD */
270                 if (unlikely(opt->ra)) {
271                         /* Check if this is a mld message */
272                         u8 *ptr = skb_network_header(skb) + opt->ra;
273                         struct icmp6hdr *icmp6;
274                         u8 nexthdr = hdr->nexthdr;
275                         int offset;
276 
277                         /* Check if the value of Router Alert
278                          * is for MLD (0x0000).
279                          */
280                         if ((ptr[2] | ptr[3]) == 0) {
281                                 deliver = 0;
282 
283                                 if (!ipv6_ext_hdr(nexthdr)) {
284                                         /* BUG */
285                                         goto out;
286                                 }
287                                 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
288                                                           &nexthdr);
289                                 if (offset < 0)
290                                         goto out;
291 
292                                 if (nexthdr != IPPROTO_ICMPV6)
293                                         goto out;
294 
295                                 if (!pskb_may_pull(skb, (skb_network_header(skb) +
296                                                    offset + 1 - skb->data)))
297                                         goto out;
298 
299                                 icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
300 
301                                 switch (icmp6->icmp6_type) {
302                                 case ICMPV6_MGM_QUERY:
303                                 case ICMPV6_MGM_REPORT:
304                                 case ICMPV6_MGM_REDUCTION:
305                                 case ICMPV6_MLD2_REPORT:
306                                         deliver = 1;
307                                         break;
308                                 }
309                                 goto out;
310                         }
311                         /* unknown RA - process it normally */
312                 }
313 
314                 if (deliver)
315                         skb2 = skb_clone(skb, GFP_ATOMIC);
316                 else {
317                         skb2 = skb;
318                         skb = NULL;
319                 }
320 
321                 if (skb2) {
322                         ip6_mr_input(skb2);
323                 }
324         }
325 out:
326 #endif
327         if (likely(deliver))
328                 ip6_input(skb);
329         else {
330                 /* discard */
331                 kfree_skb(skb);
332         }
333 
334         return 0;
335 }
336 

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