xref: /openbmc/linux/net/ipv6/ip6_input.c (revision 861e10be) 
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 
50 int ip6_rcv_finish(struct sk_buff *skb)
51 {
52 	if (sysctl_ip_early_demux && !skb_dst(skb)) {
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 	/*
113 	 * RFC4291 2.5.3
114 	 * A packet received on an interface with a destination address
115 	 * of loopback must be dropped.
116 	 */
117 	if (!(dev->flags & IFF_LOOPBACK) &&
118 	    ipv6_addr_loopback(&hdr->daddr))
119 		goto err;
120 
121 	/*
122 	 * RFC4291 2.7
123 	 * Multicast addresses must not be used as source addresses in IPv6
124 	 * packets or appear in any Routing header.
125 	 */
126 	if (ipv6_addr_is_multicast(&hdr->saddr))
127 		goto err;
128 
129 	skb->transport_header = skb->network_header + sizeof(*hdr);
130 	IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
131 
132 	pkt_len = ntohs(hdr->payload_len);
133 
134 	/* pkt_len may be zero if Jumbo payload option is present */
135 	if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
136 		if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
137 			IP6_INC_STATS_BH(net,
138 					 idev, IPSTATS_MIB_INTRUNCATEDPKTS);
139 			goto drop;
140 		}
141 		if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
142 			IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
143 			goto drop;
144 		}
145 		hdr = ipv6_hdr(skb);
146 	}
147 
148 	if (hdr->nexthdr == NEXTHDR_HOP) {
149 		if (ipv6_parse_hopopts(skb) < 0) {
150 			IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
151 			rcu_read_unlock();
152 			return NET_RX_DROP;
153 		}
154 	}
155 
156 	rcu_read_unlock();
157 
158 	/* Must drop socket now because of tproxy. */
159 	skb_orphan(skb);
160 
161 	return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, dev, NULL,
162 		       ip6_rcv_finish);
163 err:
164 	IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
165 drop:
166 	rcu_read_unlock();
167 	kfree_skb(skb);
168 	return NET_RX_DROP;
169 }
170 
171 /*
172  *	Deliver the packet to the host
173  */
174 
175 
176 static int ip6_input_finish(struct sk_buff *skb)
177 {
178 	struct net *net = dev_net(skb_dst(skb)->dev);
179 	const struct inet6_protocol *ipprot;
180 	struct inet6_dev *idev;
181 	unsigned int nhoff;
182 	int nexthdr;
183 	bool raw;
184 
185 	/*
186 	 *	Parse extension headers
187 	 */
188 
189 	rcu_read_lock();
190 resubmit:
191 	idev = ip6_dst_idev(skb_dst(skb));
192 	if (!pskb_pull(skb, skb_transport_offset(skb)))
193 		goto discard;
194 	nhoff = IP6CB(skb)->nhoff;
195 	nexthdr = skb_network_header(skb)[nhoff];
196 
197 	raw = raw6_local_deliver(skb, nexthdr);
198 	if ((ipprot = rcu_dereference(inet6_protos[nexthdr])) != NULL) {
199 		int ret;
200 
201 		if (ipprot->flags & INET6_PROTO_FINAL) {
202 			const struct ipv6hdr *hdr;
203 
204 			/* Free reference early: we don't need it any more,
205 			   and it may hold ip_conntrack module loaded
206 			   indefinitely. */
207 			nf_reset(skb);
208 
209 			skb_postpull_rcsum(skb, skb_network_header(skb),
210 					   skb_network_header_len(skb));
211 			hdr = ipv6_hdr(skb);
212 			if (ipv6_addr_is_multicast(&hdr->daddr) &&
213 			    !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
214 			    &hdr->saddr) &&
215 			    !ipv6_is_mld(skb, nexthdr))
216 				goto discard;
217 		}
218 		if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
219 		    !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
220 			goto discard;
221 
222 		ret = ipprot->handler(skb);
223 		if (ret > 0)
224 			goto resubmit;
225 		else if (ret == 0)
226 			IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
227 	} else {
228 		if (!raw) {
229 			if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
230 				IP6_INC_STATS_BH(net, idev,
231 						 IPSTATS_MIB_INUNKNOWNPROTOS);
232 				icmpv6_send(skb, ICMPV6_PARAMPROB,
233 					    ICMPV6_UNK_NEXTHDR, nhoff);
234 			}
235 		} else
236 			IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
237 		kfree_skb(skb);
238 	}
239 	rcu_read_unlock();
240 	return 0;
241 
242 discard:
243 	IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
244 	rcu_read_unlock();
245 	kfree_skb(skb);
246 	return 0;
247 }
248 
249 
250 int ip6_input(struct sk_buff *skb)
251 {
252 	return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
253 		       ip6_input_finish);
254 }
255 
256 int ip6_mc_input(struct sk_buff *skb)
257 {
258 	const struct ipv6hdr *hdr;
259 	bool deliver;
260 
261 	IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev),
262 			 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
263 			 skb->len);
264 
265 	hdr = ipv6_hdr(skb);
266 	deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
267 
268 #ifdef CONFIG_IPV6_MROUTE
269 	/*
270 	 *      IPv6 multicast router mode is now supported ;)
271 	 */
272 	if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
273 	    !(ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) &&
274 	    likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
275 		/*
276 		 * Okay, we try to forward - split and duplicate
277 		 * packets.
278 		 */
279 		struct sk_buff *skb2;
280 		struct inet6_skb_parm *opt = IP6CB(skb);
281 
282 		/* Check for MLD */
283 		if (unlikely(opt->ra)) {
284 			/* Check if this is a mld message */
285 			u8 *ptr = skb_network_header(skb) + opt->ra;
286 			struct icmp6hdr *icmp6;
287 			u8 nexthdr = hdr->nexthdr;
288 			__be16 frag_off;
289 			int offset;
290 
291 			/* Check if the value of Router Alert
292 			 * is for MLD (0x0000).
293 			 */
294 			if ((ptr[2] | ptr[3]) == 0) {
295 				deliver = false;
296 
297 				if (!ipv6_ext_hdr(nexthdr)) {
298 					/* BUG */
299 					goto out;
300 				}
301 				offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
302 							  &nexthdr, &frag_off);
303 				if (offset < 0)
304 					goto out;
305 
306 				if (nexthdr != IPPROTO_ICMPV6)
307 					goto out;
308 
309 				if (!pskb_may_pull(skb, (skb_network_header(skb) +
310 						   offset + 1 - skb->data)))
311 					goto out;
312 
313 				icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
314 
315 				switch (icmp6->icmp6_type) {
316 				case ICMPV6_MGM_QUERY:
317 				case ICMPV6_MGM_REPORT:
318 				case ICMPV6_MGM_REDUCTION:
319 				case ICMPV6_MLD2_REPORT:
320 					deliver = true;
321 					break;
322 				}
323 				goto out;
324 			}
325 			/* unknown RA - process it normally */
326 		}
327 
328 		if (deliver)
329 			skb2 = skb_clone(skb, GFP_ATOMIC);
330 		else {
331 			skb2 = skb;
332 			skb = NULL;
333 		}
334 
335 		if (skb2) {
336 			ip6_mr_input(skb2);
337 		}
338 	}
339 out:
340 #endif
341 	if (likely(deliver))
342 		ip6_input(skb);
343 	else {
344 		/* discard */
345 		kfree_skb(skb);
346 	}
347 
348 	return 0;
349 }
350