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 (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	/* 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,
187		       net, NULL, skb, dev, NULL,
188		       ip6_rcv_finish);
189err:
190	IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
191drop:
192	rcu_read_unlock();
193	kfree_skb(skb);
194	return NET_RX_DROP;
195}
196
197/*
198 *	Deliver the packet to the host
199 */
200
201
202static int ip6_input_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
203{
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();
215resubmit:
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
270discard:
271	IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
272	rcu_read_unlock();
273	kfree_skb(skb);
274	return 0;
275}
276
277
278int ip6_input(struct sk_buff *skb)
279{
280	return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN,
281		       dev_net(skb->dev), NULL, skb, skb->dev, NULL,
282		       ip6_input_finish);
283}
284
285int 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	}
353out:
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