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
ip6_rcv_finish(struct sk_buff * skb)50 inline 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
ipv6_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt,struct net_device * orig_dev)58 int 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 /* RFC4291 Errata ID: 3480
115 * Interface-Local scope spans only a single interface on a
116 * node and is useful only for loopback transmission of
117 * multicast. Packets with interface-local scope received
118 * from another node must be discarded.
119 */
120 if (!(skb->pkt_type == PACKET_LOOPBACK ||
121 dev->flags & IFF_LOOPBACK) &&
122 ipv6_addr_is_multicast(&hdr->daddr) &&
123 IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1)
124 goto err;
125
126 /* RFC4291 2.7
127 * Nodes must not originate a packet to a multicast address whose scope
128 * field contains the reserved value 0; if such a packet is received, it
129 * must be silently dropped.
130 */
131 if (ipv6_addr_is_multicast(&hdr->daddr) &&
132 IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0)
133 goto err;
134
135 /*
136 * RFC4291 2.7
137 * Multicast addresses must not be used as source addresses in IPv6
138 * packets or appear in any Routing header.
139 */
140 if (ipv6_addr_is_multicast(&hdr->saddr))
141 goto err;
142
143 skb->transport_header = skb->network_header + sizeof(*hdr);
144 IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
145
146 pkt_len = ntohs(hdr->payload_len);
147
148 /* pkt_len may be zero if Jumbo payload option is present */
149 if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
150 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
151 IP6_INC_STATS_BH(net,
152 idev, IPSTATS_MIB_INTRUNCATEDPKTS);
153 goto drop;
154 }
155 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
156 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
157 goto drop;
158 }
159 hdr = ipv6_hdr(skb);
160 }
161
162 if (hdr->nexthdr == NEXTHDR_HOP) {
163 if (ipv6_parse_hopopts(skb) < 0) {
164 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
165 rcu_read_unlock();
166 return NET_RX_DROP;
167 }
168 }
169
170 rcu_read_unlock();
171
172 /* Must drop socket now because of tproxy. */
173 skb_orphan(skb);
174
175 return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, dev, NULL,
176 ip6_rcv_finish);
177 err:
178 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
179 drop:
180 rcu_read_unlock();
181 kfree_skb(skb);
182 return NET_RX_DROP;
183 }
184
185 /*
186 * Deliver the packet to the host
187 */
188
189
ip6_input_finish(struct sk_buff * skb)190 static int ip6_input_finish(struct sk_buff *skb)
191 {
192 const struct inet6_protocol *ipprot;
193 unsigned int nhoff;
194 int nexthdr, raw;
195 u8 hash;
196 struct inet6_dev *idev;
197 struct net *net = dev_net(skb_dst(skb)->dev);
198
199 /*
200 * Parse extension headers
201 */
202
203 rcu_read_lock();
204 resubmit:
205 idev = ip6_dst_idev(skb_dst(skb));
206 if (!pskb_pull(skb, skb_transport_offset(skb)))
207 goto discard;
208 nhoff = IP6CB(skb)->nhoff;
209 nexthdr = skb_network_header(skb)[nhoff];
210
211 raw = raw6_local_deliver(skb, nexthdr);
212
213 hash = nexthdr & (MAX_INET_PROTOS - 1);
214 if ((ipprot = rcu_dereference(inet6_protos[hash])) != NULL) {
215 int ret;
216
217 if (ipprot->flags & INET6_PROTO_FINAL) {
218 const struct ipv6hdr *hdr;
219
220 /* Free reference early: we don't need it any more,
221 and it may hold ip_conntrack module loaded
222 indefinitely. */
223 nf_reset(skb);
224
225 skb_postpull_rcsum(skb, skb_network_header(skb),
226 skb_network_header_len(skb));
227 hdr = ipv6_hdr(skb);
228 if (ipv6_addr_is_multicast(&hdr->daddr) &&
229 !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
230 &hdr->saddr) &&
231 !ipv6_is_mld(skb, nexthdr))
232 goto discard;
233 }
234 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
235 !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
236 goto discard;
237
238 ret = ipprot->handler(skb);
239 if (ret > 0)
240 goto resubmit;
241 else if (ret == 0)
242 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
243 } else {
244 if (!raw) {
245 if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
246 IP6_INC_STATS_BH(net, idev,
247 IPSTATS_MIB_INUNKNOWNPROTOS);
248 icmpv6_send(skb, ICMPV6_PARAMPROB,
249 ICMPV6_UNK_NEXTHDR, nhoff);
250 }
251 } else
252 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
253 kfree_skb(skb);
254 }
255 rcu_read_unlock();
256 return 0;
257
258 discard:
259 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
260 rcu_read_unlock();
261 kfree_skb(skb);
262 return 0;
263 }
264
265
ip6_input(struct sk_buff * skb)266 int ip6_input(struct sk_buff *skb)
267 {
268 return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
269 ip6_input_finish);
270 }
271
ip6_mc_input(struct sk_buff * skb)272 int ip6_mc_input(struct sk_buff *skb)
273 {
274 const struct ipv6hdr *hdr;
275 int deliver;
276
277 IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev),
278 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
279 skb->len);
280
281 hdr = ipv6_hdr(skb);
282 deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
283
284 #ifdef CONFIG_IPV6_MROUTE
285 /*
286 * IPv6 multicast router mode is now supported ;)
287 */
288 if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
289 !(ipv6_addr_type(&hdr->daddr) &
290 (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) &&
291 likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
292 /*
293 * Okay, we try to forward - split and duplicate
294 * packets.
295 */
296 struct sk_buff *skb2;
297 struct inet6_skb_parm *opt = IP6CB(skb);
298
299 /* Check for MLD */
300 if (unlikely(opt->ra)) {
301 /* Check if this is a mld message */
302 u8 *ptr = skb_network_header(skb) + opt->ra;
303 struct icmp6hdr *icmp6;
304 u8 nexthdr = hdr->nexthdr;
305 __be16 frag_off;
306 int offset;
307
308 /* Check if the value of Router Alert
309 * is for MLD (0x0000).
310 */
311 if ((ptr[2] | ptr[3]) == 0) {
312 deliver = 0;
313
314 if (!ipv6_ext_hdr(nexthdr)) {
315 /* BUG */
316 goto out;
317 }
318 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
319 &nexthdr, &frag_off);
320 if (offset < 0)
321 goto out;
322
323 if (nexthdr != IPPROTO_ICMPV6)
324 goto out;
325
326 if (!pskb_may_pull(skb, (skb_network_header(skb) +
327 offset + 1 - skb->data)))
328 goto out;
329
330 icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
331
332 switch (icmp6->icmp6_type) {
333 case ICMPV6_MGM_QUERY:
334 case ICMPV6_MGM_REPORT:
335 case ICMPV6_MGM_REDUCTION:
336 case ICMPV6_MLD2_REPORT:
337 deliver = 1;
338 break;
339 }
340 goto out;
341 }
342 /* unknown RA - process it normally */
343 }
344
345 if (deliver)
346 skb2 = skb_clone(skb, GFP_ATOMIC);
347 else {
348 skb2 = skb;
349 skb = NULL;
350 }
351
352 if (skb2) {
353 ip6_mr_input(skb2);
354 }
355 }
356 out:
357 #endif
358 if (likely(deliver))
359 ip6_input(skb);
360 else {
361 /* discard */
362 kfree_skb(skb);
363 }
364
365 return 0;
366 }
367