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v4.6
  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#include <net/dst_metadata.h>
 49
 50int ip6_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 51{
 52	if (net->ipv4.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_valid_dst(skb))
 60		ip6_route_input(skb);
 61
 62	return dst_input(skb);
 63}
 64
 65int 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_valid_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(net, 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	/* If enabled, drop unicast packets that were encapsulated in link-layer
138	 * multicast or broadcast to protected against the so-called "hole-196"
139	 * attack in 802.11 wireless.
140	 */
141	if (!ipv6_addr_is_multicast(&hdr->daddr) &&
142	    (skb->pkt_type == PACKET_BROADCAST ||
143	     skb->pkt_type == PACKET_MULTICAST) &&
144	    idev->cnf.drop_unicast_in_l2_multicast)
145		goto err;
146
147	/* RFC4291 2.7
148	 * Nodes must not originate a packet to a multicast address whose scope
149	 * field contains the reserved value 0; if such a packet is received, it
150	 * must be silently dropped.
151	 */
152	if (ipv6_addr_is_multicast(&hdr->daddr) &&
153	    IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0)
154		goto err;
155
156	/*
157	 * RFC4291 2.7
158	 * Multicast addresses must not be used as source addresses in IPv6
159	 * packets or appear in any Routing header.
160	 */
161	if (ipv6_addr_is_multicast(&hdr->saddr))
162		goto err;
163
164	skb->transport_header = skb->network_header + sizeof(*hdr);
165	IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
166
167	pkt_len = ntohs(hdr->payload_len);
168
169	/* pkt_len may be zero if Jumbo payload option is present */
170	if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
171		if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
172			IP6_INC_STATS_BH(net,
173					 idev, IPSTATS_MIB_INTRUNCATEDPKTS);
174			goto drop;
175		}
176		if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
177			IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
178			goto drop;
179		}
180		hdr = ipv6_hdr(skb);
181	}
182
183	if (hdr->nexthdr == NEXTHDR_HOP) {
184		if (ipv6_parse_hopopts(skb) < 0) {
185			IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
186			rcu_read_unlock();
187			return NET_RX_DROP;
188		}
189	}
190
191	rcu_read_unlock();
192
193	/* Must drop socket now because of tproxy. */
194	skb_orphan(skb);
195
196	return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING,
197		       net, NULL, skb, dev, NULL,
198		       ip6_rcv_finish);
199err:
200	IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
201drop:
202	rcu_read_unlock();
203	kfree_skb(skb);
204	return NET_RX_DROP;
205}
206
207/*
208 *	Deliver the packet to the host
209 */
210
211
212static int ip6_input_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
213{
214	const struct inet6_protocol *ipprot;
215	struct inet6_dev *idev;
216	unsigned int nhoff;
217	int nexthdr;
218	bool raw;
 
 
 
219
220	/*
221	 *	Parse extension headers
222	 */
223
224	rcu_read_lock();
225resubmit:
226	idev = ip6_dst_idev(skb_dst(skb));
227	if (!pskb_pull(skb, skb_transport_offset(skb)))
228		goto discard;
229	nhoff = IP6CB(skb)->nhoff;
230	nexthdr = skb_network_header(skb)[nhoff];
231
232	raw = raw6_local_deliver(skb, nexthdr);
233	ipprot = rcu_dereference(inet6_protos[nexthdr]);
234	if (ipprot) {
 
235		int ret;
236
237		if (ipprot->flags & INET6_PROTO_FINAL) {
238			const struct ipv6hdr *hdr;
239
240			/* Free reference early: we don't need it any more,
241			   and it may hold ip_conntrack module loaded
242			   indefinitely. */
243			nf_reset(skb);
244
245			skb_postpull_rcsum(skb, skb_network_header(skb),
246					   skb_network_header_len(skb));
247			hdr = ipv6_hdr(skb);
248			if (ipv6_addr_is_multicast(&hdr->daddr) &&
249			    !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
250			    &hdr->saddr) &&
251			    !ipv6_is_mld(skb, nexthdr, skb_network_header_len(skb)))
252				goto discard;
253		}
254		if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
255		    !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
256			goto discard;
257
258		ret = ipprot->handler(skb);
259		if (ret > 0)
260			goto resubmit;
261		else if (ret == 0)
262			IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
263	} else {
264		if (!raw) {
265			if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
266				IP6_INC_STATS_BH(net, idev,
267						 IPSTATS_MIB_INUNKNOWNPROTOS);
268				icmpv6_send(skb, ICMPV6_PARAMPROB,
269					    ICMPV6_UNK_NEXTHDR, nhoff);
270			}
271			kfree_skb(skb);
272		} else {
273			IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
274			consume_skb(skb);
275		}
276	}
277	rcu_read_unlock();
278	return 0;
279
280discard:
281	IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
282	rcu_read_unlock();
283	kfree_skb(skb);
284	return 0;
285}
286
287
288int ip6_input(struct sk_buff *skb)
289{
290	return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN,
291		       dev_net(skb->dev), NULL, skb, skb->dev, NULL,
292		       ip6_input_finish);
293}
294
295int ip6_mc_input(struct sk_buff *skb)
296{
297	const struct ipv6hdr *hdr;
298	bool deliver;
299
300	IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev),
301			 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
302			 skb->len);
303
304	hdr = ipv6_hdr(skb);
305	deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
306
307#ifdef CONFIG_IPV6_MROUTE
308	/*
309	 *      IPv6 multicast router mode is now supported ;)
310	 */
311	if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
312	    !(ipv6_addr_type(&hdr->daddr) &
313	      (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) &&
314	    likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
315		/*
316		 * Okay, we try to forward - split and duplicate
317		 * packets.
318		 */
319		struct sk_buff *skb2;
320		struct inet6_skb_parm *opt = IP6CB(skb);
321
322		/* Check for MLD */
323		if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) {
324			/* Check if this is a mld message */
 
 
325			u8 nexthdr = hdr->nexthdr;
326			__be16 frag_off;
327			int offset;
328
329			/* Check if the value of Router Alert
330			 * is for MLD (0x0000).
331			 */
332			if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) {
333				deliver = false;
334
335				if (!ipv6_ext_hdr(nexthdr)) {
336					/* BUG */
337					goto out;
338				}
339				offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
340							  &nexthdr, &frag_off);
341				if (offset < 0)
342					goto out;
343
344				if (ipv6_is_mld(skb, nexthdr, offset))
345					deliver = true;
 
 
 
 
346
 
 
 
 
 
 
 
 
 
 
347				goto out;
348			}
349			/* unknown RA - process it normally */
350		}
351
352		if (deliver)
353			skb2 = skb_clone(skb, GFP_ATOMIC);
354		else {
355			skb2 = skb;
356			skb = NULL;
357		}
358
359		if (skb2) {
360			ip6_mr_input(skb2);
361		}
362	}
363out:
364#endif
365	if (likely(deliver))
366		ip6_input(skb);
367	else {
368		/* discard */
369		kfree_skb(skb);
370	}
371
372	return 0;
373}
v3.5.6
  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
 
 
 
 
 48
 49
 50inline int ip6_rcv_finish( struct sk_buff *skb)
 51{
 52	if (skb_dst(skb) == NULL)
 
 53		ip6_route_input(skb);
 54
 55	return dst_input(skb);
 56}
 57
 58int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
 59{
 60	const struct ipv6hdr *hdr;
 61	u32 		pkt_len;
 62	struct inet6_dev *idev;
 63	struct net *net = dev_net(skb->dev);
 64
 65	if (skb->pkt_type == PACKET_OTHERHOST) {
 66		kfree_skb(skb);
 67		return NET_RX_DROP;
 68	}
 69
 70	rcu_read_lock();
 71
 72	idev = __in6_dev_get(skb->dev);
 73
 74	IP6_UPD_PO_STATS_BH(net, idev, IPSTATS_MIB_IN, skb->len);
 75
 76	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
 77	    !idev || unlikely(idev->cnf.disable_ipv6)) {
 78		IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
 79		goto drop;
 80	}
 81
 82	memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
 83
 84	/*
 85	 * Store incoming device index. When the packet will
 86	 * be queued, we cannot refer to skb->dev anymore.
 87	 *
 88	 * BTW, when we send a packet for our own local address on a
 89	 * non-loopback interface (e.g. ethX), it is being delivered
 90	 * via the loopback interface (lo) here; skb->dev = loopback_dev.
 91	 * It, however, should be considered as if it is being
 92	 * arrived via the sending interface (ethX), because of the
 93	 * nature of scoping architecture. --yoshfuji
 94	 */
 95	IP6CB(skb)->iif = skb_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;
 96
 97	if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
 98		goto err;
 99
100	hdr = ipv6_hdr(skb);
101
102	if (hdr->version != 6)
103		goto err;
104
 
 
 
 
105	/*
106	 * RFC4291 2.5.3
107	 * A packet received on an interface with a destination address
108	 * of loopback must be dropped.
109	 */
110	if (!(dev->flags & IFF_LOOPBACK) &&
111	    ipv6_addr_loopback(&hdr->daddr))
112		goto err;
113
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
114	/*
115	 * RFC4291 2.7
116	 * Multicast addresses must not be used as source addresses in IPv6
117	 * packets or appear in any Routing header.
118	 */
119	if (ipv6_addr_is_multicast(&hdr->saddr))
120		goto err;
121
122	skb->transport_header = skb->network_header + sizeof(*hdr);
123	IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
124
125	pkt_len = ntohs(hdr->payload_len);
126
127	/* pkt_len may be zero if Jumbo payload option is present */
128	if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
129		if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
130			IP6_INC_STATS_BH(net,
131					 idev, IPSTATS_MIB_INTRUNCATEDPKTS);
132			goto drop;
133		}
134		if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
135			IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
136			goto drop;
137		}
138		hdr = ipv6_hdr(skb);
139	}
140
141	if (hdr->nexthdr == NEXTHDR_HOP) {
142		if (ipv6_parse_hopopts(skb) < 0) {
143			IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
144			rcu_read_unlock();
145			return NET_RX_DROP;
146		}
147	}
148
149	rcu_read_unlock();
150
151	/* Must drop socket now because of tproxy. */
152	skb_orphan(skb);
153
154	return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, dev, NULL,
 
155		       ip6_rcv_finish);
156err:
157	IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
158drop:
159	rcu_read_unlock();
160	kfree_skb(skb);
161	return NET_RX_DROP;
162}
163
164/*
165 *	Deliver the packet to the host
166 */
167
168
169static int ip6_input_finish(struct sk_buff *skb)
170{
171	const struct inet6_protocol *ipprot;
 
172	unsigned int nhoff;
173	int nexthdr;
174	bool raw;
175	u8 hash;
176	struct inet6_dev *idev;
177	struct net *net = dev_net(skb_dst(skb)->dev);
178
179	/*
180	 *	Parse extension headers
181	 */
182
183	rcu_read_lock();
184resubmit:
185	idev = ip6_dst_idev(skb_dst(skb));
186	if (!pskb_pull(skb, skb_transport_offset(skb)))
187		goto discard;
188	nhoff = IP6CB(skb)->nhoff;
189	nexthdr = skb_network_header(skb)[nhoff];
190
191	raw = raw6_local_deliver(skb, nexthdr);
192
193	hash = nexthdr & (MAX_INET_PROTOS - 1);
194	if ((ipprot = rcu_dereference(inet6_protos[hash])) != NULL) {
195		int ret;
196
197		if (ipprot->flags & INET6_PROTO_FINAL) {
198			const struct ipv6hdr *hdr;
199
200			/* Free reference early: we don't need it any more,
201			   and it may hold ip_conntrack module loaded
202			   indefinitely. */
203			nf_reset(skb);
204
205			skb_postpull_rcsum(skb, skb_network_header(skb),
206					   skb_network_header_len(skb));
207			hdr = ipv6_hdr(skb);
208			if (ipv6_addr_is_multicast(&hdr->daddr) &&
209			    !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
210			    &hdr->saddr) &&
211			    !ipv6_is_mld(skb, nexthdr))
212				goto discard;
213		}
214		if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
215		    !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
216			goto discard;
217
218		ret = ipprot->handler(skb);
219		if (ret > 0)
220			goto resubmit;
221		else if (ret == 0)
222			IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
223	} else {
224		if (!raw) {
225			if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
226				IP6_INC_STATS_BH(net, idev,
227						 IPSTATS_MIB_INUNKNOWNPROTOS);
228				icmpv6_send(skb, ICMPV6_PARAMPROB,
229					    ICMPV6_UNK_NEXTHDR, nhoff);
230			}
231		} else
 
232			IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
233		kfree_skb(skb);
 
234	}
235	rcu_read_unlock();
236	return 0;
237
238discard:
239	IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
240	rcu_read_unlock();
241	kfree_skb(skb);
242	return 0;
243}
244
245
246int ip6_input(struct sk_buff *skb)
247{
248	return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
 
249		       ip6_input_finish);
250}
251
252int ip6_mc_input(struct sk_buff *skb)
253{
254	const struct ipv6hdr *hdr;
255	bool deliver;
256
257	IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev),
258			 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
259			 skb->len);
260
261	hdr = ipv6_hdr(skb);
262	deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
263
264#ifdef CONFIG_IPV6_MROUTE
265	/*
266	 *      IPv6 multicast router mode is now supported ;)
267	 */
268	if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
269	    !(ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) &&
 
270	    likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
271		/*
272		 * Okay, we try to forward - split and duplicate
273		 * packets.
274		 */
275		struct sk_buff *skb2;
276		struct inet6_skb_parm *opt = IP6CB(skb);
277
278		/* Check for MLD */
279		if (unlikely(opt->ra)) {
280			/* Check if this is a mld message */
281			u8 *ptr = skb_network_header(skb) + opt->ra;
282			struct icmp6hdr *icmp6;
283			u8 nexthdr = hdr->nexthdr;
284			__be16 frag_off;
285			int offset;
286
287			/* Check if the value of Router Alert
288			 * is for MLD (0x0000).
289			 */
290			if ((ptr[2] | ptr[3]) == 0) {
291				deliver = false;
292
293				if (!ipv6_ext_hdr(nexthdr)) {
294					/* BUG */
295					goto out;
296				}
297				offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
298							  &nexthdr, &frag_off);
299				if (offset < 0)
300					goto out;
301
302				if (nexthdr != IPPROTO_ICMPV6)
303					goto out;
304
305				if (!pskb_may_pull(skb, (skb_network_header(skb) +
306						   offset + 1 - skb->data)))
307					goto out;
308
309				icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
310
311				switch (icmp6->icmp6_type) {
312				case ICMPV6_MGM_QUERY:
313				case ICMPV6_MGM_REPORT:
314				case ICMPV6_MGM_REDUCTION:
315				case ICMPV6_MLD2_REPORT:
316					deliver = true;
317					break;
318				}
319				goto out;
320			}
321			/* unknown RA - process it normally */
322		}
323
324		if (deliver)
325			skb2 = skb_clone(skb, GFP_ATOMIC);
326		else {
327			skb2 = skb;
328			skb = NULL;
329		}
330
331		if (skb2) {
332			ip6_mr_input(skb2);
333		}
334	}
335out:
336#endif
337	if (likely(deliver))
338		ip6_input(skb);
339	else {
340		/* discard */
341		kfree_skb(skb);
342	}
343
344	return 0;
345}