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[mirror_ubuntu-bionic-kernel.git] / 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 #include <net/dst_metadata.h>
49
50 int ip6_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
51 {
52 /* if ingress device is enslaved to an L3 master device pass the
53 * skb to its handler for processing
54 */
55 skb = l3mdev_ip6_rcv(skb);
56 if (!skb)
57 return NET_RX_SUCCESS;
58
59 if (net->ipv4.sysctl_ip_early_demux && !skb_dst(skb) && skb->sk == NULL) {
60 const struct inet6_protocol *ipprot;
61
62 ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]);
63 if (ipprot && ipprot->early_demux)
64 ipprot->early_demux(skb);
65 }
66 if (!skb_valid_dst(skb))
67 ip6_route_input(skb);
68
69 return dst_input(skb);
70 }
71
72 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
73 {
74 const struct ipv6hdr *hdr;
75 u32 pkt_len;
76 struct inet6_dev *idev;
77 struct net *net = dev_net(skb->dev);
78
79 if (skb->pkt_type == PACKET_OTHERHOST) {
80 kfree_skb(skb);
81 return NET_RX_DROP;
82 }
83
84 rcu_read_lock();
85
86 idev = __in6_dev_get(skb->dev);
87
88 __IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_IN, skb->len);
89
90 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
91 !idev || unlikely(idev->cnf.disable_ipv6)) {
92 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
93 goto drop;
94 }
95
96 memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
97
98 /*
99 * Store incoming device index. When the packet will
100 * be queued, we cannot refer to skb->dev anymore.
101 *
102 * BTW, when we send a packet for our own local address on a
103 * non-loopback interface (e.g. ethX), it is being delivered
104 * via the loopback interface (lo) here; skb->dev = loopback_dev.
105 * It, however, should be considered as if it is being
106 * arrived via the sending interface (ethX), because of the
107 * nature of scoping architecture. --yoshfuji
108 */
109 IP6CB(skb)->iif = skb_valid_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;
110
111 if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
112 goto err;
113
114 hdr = ipv6_hdr(skb);
115
116 if (hdr->version != 6)
117 goto err;
118
119 __IP6_ADD_STATS(net, idev,
120 IPSTATS_MIB_NOECTPKTS +
121 (ipv6_get_dsfield(hdr) & INET_ECN_MASK),
122 max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
123 /*
124 * RFC4291 2.5.3
125 * A packet received on an interface with a destination address
126 * of loopback must be dropped.
127 */
128 if (!(dev->flags & IFF_LOOPBACK) &&
129 ipv6_addr_loopback(&hdr->daddr))
130 goto err;
131
132 /* RFC4291 Errata ID: 3480
133 * Interface-Local scope spans only a single interface on a
134 * node and is useful only for loopback transmission of
135 * multicast. Packets with interface-local scope received
136 * from another node must be discarded.
137 */
138 if (!(skb->pkt_type == PACKET_LOOPBACK ||
139 dev->flags & IFF_LOOPBACK) &&
140 ipv6_addr_is_multicast(&hdr->daddr) &&
141 IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1)
142 goto err;
143
144 /* If enabled, drop unicast packets that were encapsulated in link-layer
145 * multicast or broadcast to protected against the so-called "hole-196"
146 * attack in 802.11 wireless.
147 */
148 if (!ipv6_addr_is_multicast(&hdr->daddr) &&
149 (skb->pkt_type == PACKET_BROADCAST ||
150 skb->pkt_type == PACKET_MULTICAST) &&
151 idev->cnf.drop_unicast_in_l2_multicast)
152 goto err;
153
154 /* RFC4291 2.7
155 * Nodes must not originate a packet to a multicast address whose scope
156 * field contains the reserved value 0; if such a packet is received, it
157 * must be silently dropped.
158 */
159 if (ipv6_addr_is_multicast(&hdr->daddr) &&
160 IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0)
161 goto err;
162
163 /*
164 * RFC4291 2.7
165 * Multicast addresses must not be used as source addresses in IPv6
166 * packets or appear in any Routing header.
167 */
168 if (ipv6_addr_is_multicast(&hdr->saddr))
169 goto err;
170
171 skb->transport_header = skb->network_header + sizeof(*hdr);
172 IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
173
174 pkt_len = ntohs(hdr->payload_len);
175
176 /* pkt_len may be zero if Jumbo payload option is present */
177 if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
178 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
179 __IP6_INC_STATS(net,
180 idev, IPSTATS_MIB_INTRUNCATEDPKTS);
181 goto drop;
182 }
183 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
184 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
185 goto drop;
186 }
187 hdr = ipv6_hdr(skb);
188 }
189
190 if (hdr->nexthdr == NEXTHDR_HOP) {
191 if (ipv6_parse_hopopts(skb) < 0) {
192 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
193 rcu_read_unlock();
194 return NET_RX_DROP;
195 }
196 }
197
198 rcu_read_unlock();
199
200 /* Must drop socket now because of tproxy. */
201 skb_orphan(skb);
202
203 return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING,
204 net, NULL, skb, dev, NULL,
205 ip6_rcv_finish);
206 err:
207 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
208 drop:
209 rcu_read_unlock();
210 kfree_skb(skb);
211 return NET_RX_DROP;
212 }
213
214 /*
215 * Deliver the packet to the host
216 */
217
218
219 static int ip6_input_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
220 {
221 const struct inet6_protocol *ipprot;
222 struct inet6_dev *idev;
223 unsigned int nhoff;
224 int nexthdr;
225 bool raw;
226 bool have_final = false;
227
228 /*
229 * Parse extension headers
230 */
231
232 rcu_read_lock();
233 resubmit:
234 idev = ip6_dst_idev(skb_dst(skb));
235 if (!pskb_pull(skb, skb_transport_offset(skb)))
236 goto discard;
237 nhoff = IP6CB(skb)->nhoff;
238 nexthdr = skb_network_header(skb)[nhoff];
239
240 resubmit_final:
241 raw = raw6_local_deliver(skb, nexthdr);
242 ipprot = rcu_dereference(inet6_protos[nexthdr]);
243 if (ipprot) {
244 int ret;
245
246 if (have_final) {
247 if (!(ipprot->flags & INET6_PROTO_FINAL)) {
248 /* Once we've seen a final protocol don't
249 * allow encapsulation on any non-final
250 * ones. This allows foo in UDP encapsulation
251 * to work.
252 */
253 goto discard;
254 }
255 } else if (ipprot->flags & INET6_PROTO_FINAL) {
256 const struct ipv6hdr *hdr;
257
258 /* Only do this once for first final protocol */
259 have_final = true;
260
261 /* Free reference early: we don't need it any more,
262 and it may hold ip_conntrack module loaded
263 indefinitely. */
264 nf_reset(skb);
265
266 skb_postpull_rcsum(skb, skb_network_header(skb),
267 skb_network_header_len(skb));
268 hdr = ipv6_hdr(skb);
269 if (ipv6_addr_is_multicast(&hdr->daddr) &&
270 !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
271 &hdr->saddr) &&
272 !ipv6_is_mld(skb, nexthdr, skb_network_header_len(skb)))
273 goto discard;
274 }
275 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
276 !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
277 goto discard;
278
279 ret = ipprot->handler(skb);
280 if (ret > 0) {
281 if (ipprot->flags & INET6_PROTO_FINAL) {
282 /* Not an extension header, most likely UDP
283 * encapsulation. Use return value as nexthdr
284 * protocol not nhoff (which presumably is
285 * not set by handler).
286 */
287 nexthdr = ret;
288 goto resubmit_final;
289 } else {
290 goto resubmit;
291 }
292 } else if (ret == 0) {
293 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS);
294 }
295 } else {
296 if (!raw) {
297 if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
298 __IP6_INC_STATS(net, idev,
299 IPSTATS_MIB_INUNKNOWNPROTOS);
300 icmpv6_send(skb, ICMPV6_PARAMPROB,
301 ICMPV6_UNK_NEXTHDR, nhoff);
302 }
303 kfree_skb(skb);
304 } else {
305 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS);
306 consume_skb(skb);
307 }
308 }
309 rcu_read_unlock();
310 return 0;
311
312 discard:
313 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
314 rcu_read_unlock();
315 kfree_skb(skb);
316 return 0;
317 }
318
319
320 int ip6_input(struct sk_buff *skb)
321 {
322 return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN,
323 dev_net(skb->dev), NULL, skb, skb->dev, NULL,
324 ip6_input_finish);
325 }
326 EXPORT_SYMBOL_GPL(ip6_input);
327
328 int ip6_mc_input(struct sk_buff *skb)
329 {
330 const struct ipv6hdr *hdr;
331 bool deliver;
332
333 __IP6_UPD_PO_STATS(dev_net(skb_dst(skb)->dev),
334 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
335 skb->len);
336
337 hdr = ipv6_hdr(skb);
338 deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
339
340 #ifdef CONFIG_IPV6_MROUTE
341 /*
342 * IPv6 multicast router mode is now supported ;)
343 */
344 if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
345 !(ipv6_addr_type(&hdr->daddr) &
346 (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) &&
347 likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
348 /*
349 * Okay, we try to forward - split and duplicate
350 * packets.
351 */
352 struct sk_buff *skb2;
353 struct inet6_skb_parm *opt = IP6CB(skb);
354
355 /* Check for MLD */
356 if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) {
357 /* Check if this is a mld message */
358 u8 nexthdr = hdr->nexthdr;
359 __be16 frag_off;
360 int offset;
361
362 /* Check if the value of Router Alert
363 * is for MLD (0x0000).
364 */
365 if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) {
366 deliver = false;
367
368 if (!ipv6_ext_hdr(nexthdr)) {
369 /* BUG */
370 goto out;
371 }
372 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
373 &nexthdr, &frag_off);
374 if (offset < 0)
375 goto out;
376
377 if (ipv6_is_mld(skb, nexthdr, offset))
378 deliver = true;
379
380 goto out;
381 }
382 /* unknown RA - process it normally */
383 }
384
385 if (deliver)
386 skb2 = skb_clone(skb, GFP_ATOMIC);
387 else {
388 skb2 = skb;
389 skb = NULL;
390 }
391
392 if (skb2) {
393 ip6_mr_input(skb2);
394 }
395 }
396 out:
397 #endif
398 if (likely(deliver))
399 ip6_input(skb);
400 else {
401 /* discard */
402 kfree_skb(skb);
403 }
404
405 return 0;
406 }