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Linux/net/ipv6/ip6_input.c

  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 #include <linux/slab.h>
 32 
 33 #include <linux/netfilter.h>
 34 #include <linux/netfilter_ipv6.h>
 35 
 36 #include <net/sock.h>
 37 #include <net/snmp.h>
 38 
 39 #include <net/ipv6.h>
 40 #include <net/protocol.h>
 41 #include <net/transp_v6.h>
 42 #include <net/rawv6.h>
 43 #include <net/ndisc.h>
 44 #include <net/ip6_route.h>
 45 #include <net/addrconf.h>
 46 #include <net/xfrm.h>
 47 #include <net/inet_ecn.h>
 48 
 49 
 50 int ip6_rcv_finish(struct sk_buff *skb)
 51 {
 52         if (sysctl_ip_early_demux && !skb_dst(skb) && skb->sk == NULL) {
 53                 const struct inet6_protocol *ipprot;
 54 
 55                 ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]);
 56                 if (ipprot && ipprot->early_demux)
 57                         ipprot->early_demux(skb);
 58         }
 59         if (!skb_dst(skb))
 60                 ip6_route_input(skb);
 61 
 62         return dst_input(skb);
 63 }
 64 
 65 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
 66 {
 67         const struct ipv6hdr *hdr;
 68         u32             pkt_len;
 69         struct inet6_dev *idev;
 70         struct net *net = dev_net(skb->dev);
 71 
 72         if (skb->pkt_type == PACKET_OTHERHOST) {
 73                 kfree_skb(skb);
 74                 return NET_RX_DROP;
 75         }
 76 
 77         rcu_read_lock();
 78 
 79         idev = __in6_dev_get(skb->dev);
 80 
 81         IP6_UPD_PO_STATS_BH(net, idev, IPSTATS_MIB_IN, skb->len);
 82 
 83         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
 84             !idev || unlikely(idev->cnf.disable_ipv6)) {
 85                 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
 86                 goto drop;
 87         }
 88 
 89         memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
 90 
 91         /*
 92          * Store incoming device index. When the packet will
 93          * be queued, we cannot refer to skb->dev anymore.
 94          *
 95          * BTW, when we send a packet for our own local address on a
 96          * non-loopback interface (e.g. ethX), it is being delivered
 97          * via the loopback interface (lo) here; skb->dev = loopback_dev.
 98          * It, however, should be considered as if it is being
 99          * arrived via the sending interface (ethX), because of the
100          * nature of scoping architecture. --yoshfuji
101          */
102         IP6CB(skb)->iif = skb_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;
103 
104         if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
105                 goto err;
106 
107         hdr = ipv6_hdr(skb);
108 
109         if (hdr->version != 6)
110                 goto err;
111 
112         IP6_ADD_STATS_BH(dev_net(dev), idev,
113                          IPSTATS_MIB_NOECTPKTS +
114                                 (ipv6_get_dsfield(hdr) & INET_ECN_MASK),
115                          max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
116         /*
117          * RFC4291 2.5.3
118          * A packet received on an interface with a destination address
119          * of loopback must be dropped.
120          */
121         if (!(dev->flags & IFF_LOOPBACK) &&
122             ipv6_addr_loopback(&hdr->daddr))
123                 goto err;
124 
125         /* RFC4291 Errata ID: 3480
126          * Interface-Local scope spans only a single interface on a
127          * node and is useful only for loopback transmission of
128          * multicast.  Packets with interface-local scope received
129          * from another node must be discarded.
130          */
131         if (!(skb->pkt_type == PACKET_LOOPBACK ||
132               dev->flags & IFF_LOOPBACK) &&
133             ipv6_addr_is_multicast(&hdr->daddr) &&
134             IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1)
135                 goto err;
136 
137         /* RFC4291 2.7
138          * Nodes must not originate a packet to a multicast address whose scope
139          * field contains the reserved value 0; if such a packet is received, it
140          * must be silently dropped.
141          */
142         if (ipv6_addr_is_multicast(&hdr->daddr) &&
143             IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0)
144                 goto err;
145 
146         /*
147          * RFC4291 2.7
148          * Multicast addresses must not be used as source addresses in IPv6
149          * packets or appear in any Routing header.
150          */
151         if (ipv6_addr_is_multicast(&hdr->saddr))
152                 goto err;
153 
154         skb->transport_header = skb->network_header + sizeof(*hdr);
155         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
156 
157         pkt_len = ntohs(hdr->payload_len);
158 
159         /* pkt_len may be zero if Jumbo payload option is present */
160         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
161                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
162                         IP6_INC_STATS_BH(net,
163                                          idev, IPSTATS_MIB_INTRUNCATEDPKTS);
164                         goto drop;
165                 }
166                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
167                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
168                         goto drop;
169                 }
170                 hdr = ipv6_hdr(skb);
171         }
172 
173         if (hdr->nexthdr == NEXTHDR_HOP) {
174                 if (ipv6_parse_hopopts(skb) < 0) {
175                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
176                         rcu_read_unlock();
177                         return NET_RX_DROP;
178                 }
179         }
180 
181         rcu_read_unlock();
182 
183         /* Must drop socket now because of tproxy. */
184         skb_orphan(skb);
185 
186         return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, dev, NULL,
187                        ip6_rcv_finish);
188 err:
189         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
190 drop:
191         rcu_read_unlock();
192         kfree_skb(skb);
193         return NET_RX_DROP;
194 }
195 
196 /*
197  *      Deliver the packet to the host
198  */
199 
200 
201 static int ip6_input_finish(struct sk_buff *skb)
202 {
203         struct net *net = dev_net(skb_dst(skb)->dev);
204         const struct inet6_protocol *ipprot;
205         struct inet6_dev *idev;
206         unsigned int nhoff;
207         int nexthdr;
208         bool raw;
209 
210         /*
211          *      Parse extension headers
212          */
213 
214         rcu_read_lock();
215 resubmit:
216         idev = ip6_dst_idev(skb_dst(skb));
217         if (!pskb_pull(skb, skb_transport_offset(skb)))
218                 goto discard;
219         nhoff = IP6CB(skb)->nhoff;
220         nexthdr = skb_network_header(skb)[nhoff];
221 
222         raw = raw6_local_deliver(skb, nexthdr);
223         if ((ipprot = rcu_dereference(inet6_protos[nexthdr])) != NULL) {
224                 int ret;
225 
226                 if (ipprot->flags & INET6_PROTO_FINAL) {
227                         const struct ipv6hdr *hdr;
228 
229                         /* Free reference early: we don't need it any more,
230                            and it may hold ip_conntrack module loaded
231                            indefinitely. */
232                         nf_reset(skb);
233 
234                         skb_postpull_rcsum(skb, skb_network_header(skb),
235                                            skb_network_header_len(skb));
236                         hdr = ipv6_hdr(skb);
237                         if (ipv6_addr_is_multicast(&hdr->daddr) &&
238                             !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
239                             &hdr->saddr) &&
240                             !ipv6_is_mld(skb, nexthdr, skb_network_header_len(skb)))
241                                 goto discard;
242                 }
243                 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
244                     !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
245                         goto discard;
246 
247                 ret = ipprot->handler(skb);
248                 if (ret > 0)
249                         goto resubmit;
250                 else if (ret == 0)
251                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
252         } else {
253                 if (!raw) {
254                         if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
255                                 IP6_INC_STATS_BH(net, idev,
256                                                  IPSTATS_MIB_INUNKNOWNPROTOS);
257                                 icmpv6_send(skb, ICMPV6_PARAMPROB,
258                                             ICMPV6_UNK_NEXTHDR, nhoff);
259                         }
260                         kfree_skb(skb);
261                 } else {
262                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
263                         consume_skb(skb);
264                 }
265         }
266         rcu_read_unlock();
267         return 0;
268 
269 discard:
270         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
271         rcu_read_unlock();
272         kfree_skb(skb);
273         return 0;
274 }
275 
276 
277 int ip6_input(struct sk_buff *skb)
278 {
279         return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
280                        ip6_input_finish);
281 }
282 
283 int ip6_mc_input(struct sk_buff *skb)
284 {
285         const struct ipv6hdr *hdr;
286         bool deliver;
287 
288         IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev),
289                          ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
290                          skb->len);
291 
292         hdr = ipv6_hdr(skb);
293         deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
294 
295 #ifdef CONFIG_IPV6_MROUTE
296         /*
297          *      IPv6 multicast router mode is now supported ;)
298          */
299         if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
300             !(ipv6_addr_type(&hdr->daddr) &
301               (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) &&
302             likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
303                 /*
304                  * Okay, we try to forward - split and duplicate
305                  * packets.
306                  */
307                 struct sk_buff *skb2;
308                 struct inet6_skb_parm *opt = IP6CB(skb);
309 
310                 /* Check for MLD */
311                 if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) {
312                         /* Check if this is a mld message */
313                         u8 nexthdr = hdr->nexthdr;
314                         __be16 frag_off;
315                         int offset;
316 
317                         /* Check if the value of Router Alert
318                          * is for MLD (0x0000).
319                          */
320                         if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) {
321                                 deliver = false;
322 
323                                 if (!ipv6_ext_hdr(nexthdr)) {
324                                         /* BUG */
325                                         goto out;
326                                 }
327                                 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
328                                                           &nexthdr, &frag_off);
329                                 if (offset < 0)
330                                         goto out;
331 
332                                 if (!ipv6_is_mld(skb, nexthdr, offset))
333                                         goto out;
334 
335                                 deliver = true;
336                         }
337                         /* unknown RA - process it normally */
338                 }
339 
340                 if (deliver)
341                         skb2 = skb_clone(skb, GFP_ATOMIC);
342                 else {
343                         skb2 = skb;
344                         skb = NULL;
345                 }
346 
347                 if (skb2) {
348                         ip6_mr_input(skb2);
349                 }
350         }
351 out:
352 #endif
353         if (likely(deliver))
354                 ip6_input(skb);
355         else {
356                 /* discard */
357                 kfree_skb(skb);
358         }
359 
360         return 0;
361 }
362 

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