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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 int ip6_rcv_finish(struct sock *sk, struct sk_buff *skb)
 50 {
 51         if (sysctl_ip_early_demux && !skb_dst(skb) && skb->sk == NULL) {
 52                 const struct inet6_protocol *ipprot;
 53 
 54                 ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]);
 55                 if (ipprot && ipprot->early_demux)
 56                         ipprot->early_demux(skb);
 57         }
 58         if (!skb_dst(skb))
 59                 ip6_route_input(skb);
 60 
 61         return dst_input(skb);
 62 }
 63 
 64 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
 65 {
 66         const struct ipv6hdr *hdr;
 67         u32 pkt_len;
 68         struct inet6_dev *idev;
 69         struct net *net = dev_net(skb->dev);
 70 
 71         if (skb->pkt_type == PACKET_OTHERHOST) {
 72                 kfree_skb(skb);
 73                 return NET_RX_DROP;
 74         }
 75 
 76         rcu_read_lock();
 77 
 78         idev = __in6_dev_get(skb->dev);
 79 
 80         IP6_UPD_PO_STATS_BH(net, idev, IPSTATS_MIB_IN, skb->len);
 81 
 82         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
 83             !idev || unlikely(idev->cnf.disable_ipv6)) {
 84                 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
 85                 goto drop;
 86         }
 87 
 88         memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
 89 
 90         /*
 91          * Store incoming device index. When the packet will
 92          * be queued, we cannot refer to skb->dev anymore.
 93          *
 94          * BTW, when we send a packet for our own local address on a
 95          * non-loopback interface (e.g. ethX), it is being delivered
 96          * via the loopback interface (lo) here; skb->dev = loopback_dev.
 97          * It, however, should be considered as if it is being
 98          * arrived via the sending interface (ethX), because of the
 99          * nature of scoping architecture. --yoshfuji
100          */
101         IP6CB(skb)->iif = skb_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;
102 
103         if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
104                 goto err;
105 
106         hdr = ipv6_hdr(skb);
107 
108         if (hdr->version != 6)
109                 goto err;
110 
111         IP6_ADD_STATS_BH(dev_net(dev), idev,
112                          IPSTATS_MIB_NOECTPKTS +
113                                 (ipv6_get_dsfield(hdr) & INET_ECN_MASK),
114                          max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
115         /*
116          * RFC4291 2.5.3
117          * A packet received on an interface with a destination address
118          * of loopback must be dropped.
119          */
120         if (!(dev->flags & IFF_LOOPBACK) &&
121             ipv6_addr_loopback(&hdr->daddr))
122                 goto err;
123 
124         /* RFC4291 Errata ID: 3480
125          * Interface-Local scope spans only a single interface on a
126          * node and is useful only for loopback transmission of
127          * multicast.  Packets with interface-local scope received
128          * from another node must be discarded.
129          */
130         if (!(skb->pkt_type == PACKET_LOOPBACK ||
131               dev->flags & IFF_LOOPBACK) &&
132             ipv6_addr_is_multicast(&hdr->daddr) &&
133             IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1)
134                 goto err;
135 
136         /* RFC4291 2.7
137          * Nodes must not originate a packet to a multicast address whose scope
138          * field contains the reserved value 0; if such a packet is received, it
139          * must be silently dropped.
140          */
141         if (ipv6_addr_is_multicast(&hdr->daddr) &&
142             IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0)
143                 goto err;
144 
145         /*
146          * RFC4291 2.7
147          * Multicast addresses must not be used as source addresses in IPv6
148          * packets or appear in any Routing header.
149          */
150         if (ipv6_addr_is_multicast(&hdr->saddr))
151                 goto err;
152 
153         skb->transport_header = skb->network_header + sizeof(*hdr);
154         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
155 
156         pkt_len = ntohs(hdr->payload_len);
157 
158         /* pkt_len may be zero if Jumbo payload option is present */
159         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
160                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
161                         IP6_INC_STATS_BH(net,
162                                          idev, IPSTATS_MIB_INTRUNCATEDPKTS);
163                         goto drop;
164                 }
165                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
166                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
167                         goto drop;
168                 }
169                 hdr = ipv6_hdr(skb);
170         }
171 
172         if (hdr->nexthdr == NEXTHDR_HOP) {
173                 if (ipv6_parse_hopopts(skb) < 0) {
174                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
175                         rcu_read_unlock();
176                         return NET_RX_DROP;
177                 }
178         }
179 
180         rcu_read_unlock();
181 
182         /* Must drop socket now because of tproxy. */
183         skb_orphan(skb);
184 
185         return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, NULL, skb,
186                        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 sock *sk, 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         ipprot = rcu_dereference(inet6_protos[nexthdr]);
224         if (ipprot) {
225                 int ret;
226 
227                 if (ipprot->flags & INET6_PROTO_FINAL) {
228                         const struct ipv6hdr *hdr;
229 
230                         /* Free reference early: we don't need it any more,
231                            and it may hold ip_conntrack module loaded
232                            indefinitely. */
233                         nf_reset(skb);
234 
235                         skb_postpull_rcsum(skb, skb_network_header(skb),
236                                            skb_network_header_len(skb));
237                         hdr = ipv6_hdr(skb);
238                         if (ipv6_addr_is_multicast(&hdr->daddr) &&
239                             !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
240                             &hdr->saddr) &&
241                             !ipv6_is_mld(skb, nexthdr, skb_network_header_len(skb)))
242                                 goto discard;
243                 }
244                 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
245                     !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
246                         goto discard;
247 
248                 ret = ipprot->handler(skb);
249                 if (ret > 0)
250                         goto resubmit;
251                 else if (ret == 0)
252                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
253         } else {
254                 if (!raw) {
255                         if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
256                                 IP6_INC_STATS_BH(net, idev,
257                                                  IPSTATS_MIB_INUNKNOWNPROTOS);
258                                 icmpv6_send(skb, ICMPV6_PARAMPROB,
259                                             ICMPV6_UNK_NEXTHDR, nhoff);
260                         }
261                         kfree_skb(skb);
262                 } else {
263                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
264                         consume_skb(skb);
265                 }
266         }
267         rcu_read_unlock();
268         return 0;
269 
270 discard:
271         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
272         rcu_read_unlock();
273         kfree_skb(skb);
274         return 0;
275 }
276 
277 
278 int ip6_input(struct sk_buff *skb)
279 {
280         return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, NULL, skb,
281                        skb->dev, NULL,
282                        ip6_input_finish);
283 }
284 
285 int ip6_mc_input(struct sk_buff *skb)
286 {
287         const struct ipv6hdr *hdr;
288         bool deliver;
289 
290         IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev),
291                          ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
292                          skb->len);
293 
294         hdr = ipv6_hdr(skb);
295         deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
296 
297 #ifdef CONFIG_IPV6_MROUTE
298         /*
299          *      IPv6 multicast router mode is now supported ;)
300          */
301         if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
302             !(ipv6_addr_type(&hdr->daddr) &
303               (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) &&
304             likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
305                 /*
306                  * Okay, we try to forward - split and duplicate
307                  * packets.
308                  */
309                 struct sk_buff *skb2;
310                 struct inet6_skb_parm *opt = IP6CB(skb);
311 
312                 /* Check for MLD */
313                 if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) {
314                         /* Check if this is a mld message */
315                         u8 nexthdr = hdr->nexthdr;
316                         __be16 frag_off;
317                         int offset;
318 
319                         /* Check if the value of Router Alert
320                          * is for MLD (0x0000).
321                          */
322                         if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) {
323                                 deliver = false;
324 
325                                 if (!ipv6_ext_hdr(nexthdr)) {
326                                         /* BUG */
327                                         goto out;
328                                 }
329                                 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
330                                                           &nexthdr, &frag_off);
331                                 if (offset < 0)
332                                         goto out;
333 
334                                 if (ipv6_is_mld(skb, nexthdr, offset))
335                                         deliver = true;
336 
337                                 goto out;
338                         }
339                         /* unknown RA - process it normally */
340                 }
341 
342                 if (deliver)
343                         skb2 = skb_clone(skb, GFP_ATOMIC);
344                 else {
345                         skb2 = skb;
346                         skb = NULL;
347                 }
348 
349                 if (skb2) {
350                         ip6_mr_input(skb2);
351                 }
352         }
353 out:
354 #endif
355         if (likely(deliver))
356                 ip6_input(skb);
357         else {
358                 /* discard */
359                 kfree_skb(skb);
360         }
361 
362         return 0;
363 }
364 

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